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In distributed systems, such as a network of Google Compute Engine instances, it is challenging to reliably schedule tasks because any individual instance may become unavailable due to autoscaling or network partitioning.
Google App Engine provides a Cron service. Using this service for scheduling and Google Cloud Pub/Sub for distributed messaging, you can build an application to reliably schedule tasks across a fleet of Compute Engine instances.
This three-part article includes the following:
- A design pattern for the solution.
- A sample implementation of the design pattern
- Ideas for building a production-ready version of the solution.
How to reliably schedule tasks on Google Compute Engine
Cron is the standard tool for scheduling recurring tasks on Unix systems. As the systems you build increase in complexity and become distributed, a single computer running cron can become a critical point of failure. The instance may stop due to autoscaling, or its network segment could be partitioned from systems it needs to communicate with.
Other approaches to increasing availability, such as scaled-out groups of instances behind a load balancer, don't work when you need to schedule an event that only needs to be run once by the whole system. For example, if four servers run the same singleton cron job every hour, it could create contention for resources and potential duplication of results.
Solving the problem of how to schedule tasks in a distributed system is not trivial. One solution to this problem is the Chronos framework for Apache Mesos, but this involves a significant amount of setup and management.
App Engine provides a Cron Service. If your application runs on App Engine, you can simply write App Engine handlers, schedule events, and the Cron Service will fire events and call the corresponding event handlers for your application. To run tasks on your Compute Engine instance in response to Cron Service events, you need to relay the Cron Service events to those instances.
There are several ways to do this, such as:
- Call an HTTP endpoint running on your Compute Engine instances using the App Engine URL Fetch service.
- Orchestrate tasks and locks using Google Cloud Datastore transactions.
- Pass messages from event handlers running on App Engine to your Compute Engine instances using a messaging service.
This sample illustrates the third design pattern. It is simpler to implement than managing locks and task state in Cloud Datastore. It is also more reliable than sending HTTP requests to Compute Engine instances, which may stop or lose network connectivity before a task completes.
The following diagram provides an architectural overview of this design pattern.
In this implementation, an App Engine application schedules events in the Cron Service, then transmits those events to Compute Engine instances using Google Cloud Pub/Sub. Cloud Pub/Sub is a fully-managed cloud service that provides robust, many-to-many, asynchronous messaging between applications.
A utility service on your Compute Engine instances subscribes to Cloud Pub/Sub topics and runs cron jobs in response to the events it pulls down from those topics. The utility runs standard scripts; you do not need to modify your current cron scripts to use them in this sample.
By using Cloud Pub/Sub to decouple the task-scheduling logic from the logic running the commands on Compute Engine, you can update your cron scripts as needed, without updating or re-deploying the App Engine application. You can also change your task schedule without updating the utility on your Compute Engine instances.
Because cron jobs are typically few in number and run on an hourly, weekly, or daily schedule, this design pattern should not exceed the service quotas, which are designed for high-volume operations. If it does, consider other application patterns, such as managing the timing of tasks directly in application code.
The cost of running this design pattern is less than $1 a month. This cost analysis assumes a cron job that runs every twelve hours, for an hour each time, on a f1-micro instance. For a breakdown of the costs in this estimate, and to calculate costs for your own use case, see the Google Cloud Platform Pricing Calculator.
App Engine provides a free backend quota of 8 instance-hours per day. If you are not using that quota in other applications, the App Engine cost for running this design pattern is $0, reducing the cost further.
For example, if you run the sample implementation in the following section for an hour and then delete the Google Cloud resources, the cost will be approximately 1 cent.
Sample implementation of the design pattern
A sample implementation of this design pattern, Sample: Reliable Task Scheduling on Google Compute Engine, is available on GitHub.
The sample contains two components:
An App Engine application that uses App Engine Cron Service to relay cron messages to Cloud Pub/Sub topics.
A utility that runs on Compute Engine. This utility monitors a Cloud Pub/Sub topic. When it detects a new message, it runs the corresponding command locally on the server.
The readme file included with the sample describes the sample in further detail, as well as how to run the sample code on Google Cloud Platform.
Building on the design pattern and sample
The App Engine Cron service makes it simple to set up distributed cron on your Compute Engine instances with minimal setup and cost.
The previous sample illustrated one way to implement a reliable scheduling solution for Compute Engine using the App Engine Cron Service. It's a useful design pattern because it separates the scheduling logic from the logic that runs commands on the Compute Engine instance, making it possible to change the location and execution of your tasks without having to update the scheduling logic.
The following diagram shows the flow of cron messages in this sample. By specifying which instances subscribe to a given topic, you can control whether a cron job runs on a single instance or several instances.
Another advantage of this architecture is the control it gives you over how cron jobs are routed to your instances.
You can send different cron messages to different sets of servers, as illustrated by Cloud Pub/Sub topics A and C. The tasks in Topic A are sent to a single subscriber, whereas several servers subscribe to Topic C. You might use this strategy to run one set of commands on your web server and another set on your other servers.
Another option is to run a command on one of several servers. This is illustrated by topic B. In this case, multiple servers share a single subscription and messages published to topic B are handled by the first server to claim that message and the corresponding command runs only on that server. You might use this to perform nightly data analysis that only needs to run on a single server.
You can modify the sample and use it as a model for your own application. Below are some ideas to get you started.
cron.yamlto specify your own cron messages. You can update the cron job directly, as described in Uploading Cron Jobs or re-deploy the App Engine application to update the App Engine Cron Service.
test_executor.pyto run a real script instead of
logger_sample_task.py, or write your own
Instead of manually launching the utility on Compute Engine and running it as a foreground process you can launch it automatically as a daemon by a system or third party tool like
Neither the App Engine Cron service nor Cloud Pub/Sub make strict "exactly once" delivery guarantees. While unlikely, duplicate message delivery can occur. If running a specific task more than once creates an undesirable outcome, use a distributed consistent locking tool like Zookeeper to ensure the task is run only once and by only a single instance.
When scheduling tasks, follow cron best practices and ensure that tasks are scheduled far enough apart they can complete processing before the next time they run.
Create a cost-efficient cron solution by running the utility on a micro instance. When it receives a task, it launches more powerful instances to process the cron tasks quickly. When the tasks complete, the larger instances can simply shut themselves down. This gives you flexibility to complete tasks soon after the event time, at minimal cost.
In this implementation,
cron.yamlis deployed to App Engine along with the App Engine application. This means that any change to the cron messages requires that you re-deploy the App Engine application. To avoid this, you could extend this sample implementation by rewriting the App Engine application to pull the YAML file from a Cloud Storage bucket, have it monitor the file for changes, and update App Engine Cron Service when it detects modifications to the YAML file.
Try out other Google Cloud Platform features for yourself. Have a look at our tutorials.


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Sample Page
The page below is a sample from the MediaLab course, Bone Marrow Aspiration Part I: Normal Hematopoiesis and Basic Interpretive Procedures.
Calculating and Reporting the Myeloid:Erythroid (M:E) Ratio
Once the bone marrow cell count is completed and recorded, the M: E ratio should be assessed. This is performed by calculating the total myeloid precursors in proportion to the total erythroid precursors.
Remember that this does not use the total white blood cell tally; the myeloid cells alone are counted, excluding lymphocytes, monocytes, macrophages, plasma cells, megakaryocytes, osteoclasts, osteoblasts, and other non-myeloid cells. In most circumstances, it is quite simple to divide the myeloid total by the erythroid total to find the ratio. This is always reported as a whole number ratio, and is normally around 3:1 (reference range= 2:1 to 4:1). In some situations where the erythroid portion is increased, or the myeloid series is decreased, the M:E ratio is reversed. This would still be expressed as a whole number ratio (example: 1:2). A simple way to perform the calculation is to always divide the larger value by the smaller. Which side of the colon, the 1 is placed on, is dependent on which cell type was larger. The 1 always belongs on the side of the cell type found in lower numbers.
For example:
Myeloid total 120 : Erythroid total 40
M:E ratio = 120 ÷ 40 = 3 or 3:1
So, the M:E ratio is 3:1
Another example:
Myeloid total 30 : Erythroid total 150
Divide the larger number by the smaller (notice that the placement is reversed).
150 ÷ 30 = 5
So, the M:E ratio is 1:5


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Keep up-to-date with the latest Cowbellpedia news
History of Cowbellpedia
In an era dominated by technological advancements, it is refreshing to witness an initiative that places a strong emphasis on the importance of mathematics in education. Cowbellpedia, a mathematical competition in Nigeria, has emerged as a groundbreaking platform for nurturing mathematical talent, encouraging healthy competition, and promoting excellence in the field of mathematics among secondary school students. Since its inception, Cowbellpedia has become a symbol of inspiration, resilience, and intellectual growth, showcasing the incredible potential of young minds in Nigeria.
One of the primary objectives of Cowbellpedia is to enhance the quality of mathematics education in Nigeria. By creating a competitive atmosphere, the initiative encourages students to delve deeper into the subject and explore its intricacies. Through regular practice, problem-solving, and critical thinking, participants sharpen their mathematical skills and develop a strong foundation in the subject. Cowbellpedia acts as a catalyst, igniting a passion for mathematics and pushing students to achieve their full potential.
The competition is divided into two main categories: the Junior and Senior Secondary categories. The Junior category is open to students in Junior Secondary School (JSS) while the Senior category welcomes participants from Senior Secondary School (SSS). Students from both public and private schools across Nigeria are eligible to compete. Cowbellpedia follows a rigorous selection process, with schools conducting preliminary examinations to identify their top-performing students who will represent them at the state level.
The competition progresses through several stages, starting from the preliminary rounds at the state level, followed by the regional level, and culminating in the ultimate showdown at the national level. Contestants engage in timed, written tests, which assess their problem-solving abilities and mathematical proficiency. The questions are designed to challenge participants, pushing them to think creatively and apply their knowledge in real-world scenarios.
Cowbellpedia has had a profound impact on the educational landscape in Nigeria. It has successfully fostered a culture of excellence in mathematics, encouraging students to strive for academic brilliance. The competition not only boosts students' confidence in their mathematical abilities but also instills in them essential life skills such as discipline, perseverance, and teamwork. The exposure to rigorous competition helps participants develop resilience and learn from their experiences, preparing them for future challenges.
Furthermore, Cowbellpedia has proven to be a launching pad for many young mathematical prodigies. Several past winners and participants have gone on to excel in national and international mathematics competitions, representing Nigeria and bringing accolades to their schools and the nation. Cowbellpedia serves as a stepping stone for these exceptional students, providing them with opportunities for scholarships, mentorship, and further academic pursuits in mathematics-related fields.
Cowbellpedia's success would not be possible without the dedication and support of various stakeholders. The initiative has garnered the backing of corporate sponsors, educational institutions, teachers, parents, and the government. Corporate organizations, such as Promasidor Nigeria Limited, have played a pivotal role in providing financial and logistical support, making the competition accessible to a wider audience. Educational institutions and teachers have nurtured students' mathematical talent, preparing them for the rigorous challenges of the competition. Parents have been instrumental in supporting and encouraging their children to participate, recognizing the importance of mathematics in their academic journey.
Cowbellpedia has emerged as a beacon of excellence, promoting mathematical education and competition in Nigeria. The initiative has created a platform for students to showcase their mathematical prowess, fostered a culture of academic excellence, and provided a springboard for young mathematical talents. Cowbellpedia's impact extends beyond the competition, shaping the future of mathematics education in Nigeria and inspiring generations of young minds to explore the fascinating world of numbers. As this initiative continues to thrive, it will

source: openbmb/Ultra-FineWeb


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The most common biomechanical explanation for the chin is that it acts as a buttress against masticatory stress. However, recent evidence suggests that this hypothesis is unlikely [...] More recently Ichim et al. (2007) have suggested that speech production is associated with mechanical stresses acting on the mandibular symphysis due to tongue and orofacial muscle activity. Thus, they argue that the chin is an adaptive response to resist stresses caused by oblique contractions of the genioglossus muscles during speech. Computer simulations provide results that are consistent with the orofacial stress hypothesis (Ichim et al., 2007), but this hypothesis has yet to be fully tested.
A less well-established adaptive hypothesis, but one worth considering, is that chin shape variation is a consequence of sexual selection (e.g., Hershkovitz, 1970). Psychological studies of facial attractiveness suggest that a ''broad chin'' in males is correlated with social dominance, which some females may prefer in a potential mate
Our study provides the first quantitative evidence of sexual dimorphism in chin shape among a geographically diverse sample of modern humans. The presence of sexual dimorphism appears to refute mechanical explanations of the chin that preclude sexual dimorphism, such as the masticatory and orofacial stress hypotheses (e.g. Daegling, 1993; Ichim et al., 2007).
While the presence of sexual dimorphism is consistent with the hypothesis that sexual selection influences variation in chin shape, the degree of overlap between males and females requires further explanation. It is safe to say that the male chin pales in comparison to the more exaggerated ornaments found in other animals, such as the large and colorful tail of the peacock (Pavo cristatus) (Petrie, 1991). The modest contrasts in male and female chin shape indicated by our data (see Fig. 4) do not seem to fit a runaway process of selection driven by female choice (Fisher, 1958). We suggest there are at least two possible explanations for this pattern.
One hypothesis for why male chin shape is not more exaggerated is that some females may avoid mating with extremely aggressive males
Second, the large amount of overlap in male and female chin shape may be due to regional differences inchin shape dimorphism (see Fig. 6). Regional differencesin the level of dimorphism would tend to inflate within-sex variance in the pooled human sample, thereby reducingthe probability of finding between-sex differences.
Sexual dimorphism in chin shape: Implications for adaptive hypotheses
Zaneta M. Thayer, Seth D. Dobson
The chin, or mentum osseum, is one of the most distinctive anatomical traits of modern humans. A variety of hypotheses for the adaptive value of the chin have been proposed, ranging from mechanical stress resistance to sexual selection via mate choice. While the sexual selection hypothesis predicts dimorphism in chin shape, most biomechanical hypotheses preclude it. Therefore determining the presence or absence of significant sexual dimorphism in chin shape provides a useful method for differentiating between various adaptive hypotheses; however, this has yet to be done due to a lack of quantitative data on chin shape. The goals of this study are therefore: (1) to introduce a new method for quantifying chin shape and (2) to determine the presence or absence of sexual dimorphism in chin shape in a diverse sample of modern humans. Samples were drawn from recent human skeletal collections representing nine geographic regions. Outlines of mentum osseum contours were quantified using elliptical Fourier function analysis (EFFA). Fourier coefficients were analyzed using principal components analysis (PCA). Sexual dimorphism in chin shape was assessed using PC loadings in the pooled geographic sample, and statistically significant differences were found. These findings provide the first quantitative, morphologically based evidence in support of adaptive hypotheses that predict dimorphism in chin shape, including the sexual selection hypothesis.

source: HuggingFaceFW/fineweb-edu


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To Prescribe or Not To Prescribe? Surrogate Decision Making For Life-Enhancing Products
Journal of Consumer Research, vol.
With rapid biotechnological advances in specialty drugs and direct-to-consumer advertising, consumers are under tremendous pressure to look, perform, feel, and live better. This is often accomplished through the use of life-enhancing products, sometimes referred to as performance-enhancing products, which can be accessed only through a gatekeeper, such as a physician. Integrating consumer and medical research, this article investigates how physicians make trade-offs between objective medical and nonmedical factors to determine consumers' access to life-enhancing products by examining US pediatric endocrinologists' prescription decisions for growth hormone (GH) for healthy but short children. The results of a conjoint study indicate that consumer medical criteria have less impact on a physician's decision to prescribe GH if the consumer requests a prescription or the physician believes in the intangible product benefits, and more impact when the product is more expensive. A physician's length of experience increases the impact of consumer medical criteria and decreases the influence of a consumer's preference for a prescription on the decision to prescribe. Overall, this research shows that not all consumers have equal access to life-enhancing products; their access depends on a complex combination of medical and nonmedical factors related to the consumer, product, and the physician.


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Temporary files can eat away at a your hard disk space without you ever noticing. Temporary files are typically recognized and hidden from the user's sight by the OS. Temporary files can be created when editing files, when running some programs, or when a program wishes to report and save a problem. Removing these temporary files can free up valuable space, and FSlint can find these files so that they can be purged.
It is possible to specify a minimum age to find only files modified in the last X number of days. A minimum age of 0 is all temporary files.
When a program exits or is terminated prematurely, the program can leave behind files known as core files or dump files for debugging purposes. The core files are generally named "core.#####" where # can represent any number 0-9. Many Linux distributions have this feature disabled. To check if core files are enabled on your Linux system, run 'ulimit -c' from the command line. A value of 0 is disabled. In FSlint the check box "core file mode?" enables a more thorough search for these core files.
Command Line Interface
The command line interface to this utility is 'findtf'. This utility will be found in the installation directory of fslint.
$ /usr/share/fslint/fslint/findtf --help find Temporary Files. Usage: findtf [-c] [--age=days] [[-r] [-f] paths(s)...] If -c specified then a more thorough search is done for (and only for) core files, and more information is printed about them. If --age=days specified then the temporary files must be over that number of "days" old before being reported. For e.g. findtf -c --age=4 only reports core files over 4 days old. If no path(s) specified then the current directory is assumed.


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Clue: 'The Father of the Symphony'
We have 1 answer for the clue 'The Father of the Symphony'. See the results below.
- "The Creation" composer
- Mozart contemporary
- "Surprise Symphony" composer
- Franz Joseph who was nicknamed "Papa"
- Surprise Symphony composer
- Austrian composer of "The Creation"
- Composer called the "Father of the Symphony"
- "Farewell" Symphony composer
- "Surprise" Symphony composer
- Prolific Mozart contemporary
Last Seen In:
- King Syndicate - Premier Sunday - October 23, 2011
Found an answer for the clue 'The Father of the Symphony' that we don't have? Then please submit it to us so we can make the clue database even better!


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If L is a semisimple lie algebra then L=[L,L]. Is the opposite true?
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up vote 18 down vote accepted
No. A Lie algebra satisfying that property is called perfect. For an example of a perfect Lie algebra that isn't semisimple, take a semisimple $L$ and an irreducible representation $V$ of $L$, and define a bracket on $L \times V$ by $$ [(X,v),(Y,u)] := ([X,Y],Xu-Yv). $$ This turns $L \times V$ into a perfect Lie algebra with $\text{Rad}(L \times V) = V$.
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Maybe it's also helpful to mention the substantial though often isolated literature on perfect Lie algebras and related structure theory? There are some interesting connections with other questions, as in the paper by Benkart and Zelmanov in Invent. Math. 126 (1996), 1-45. – Jim Humphreys Apr 5 '11 at 13:08
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Coronavirus and Eating Disorders Visit the hub
Online Quiz
Host a quiz night virtually or in person and help raise awareness to support people affected by eating disorders.
Looking to test your general knowledge? Using Virtual Quiz Events is a really simple way of setting up a quiz online.
The quizzes already have questions and rounds set up and take about 20 minutes to complete, so all you have to do is pick a time and invite friends to join online! They can join from anywhere without having to attend a physical location.
If you would prefer to write your own questions and host your quiz night over Facetime, Zoom or Skype, that's fine too! All you need to do is set up a JustGiving Page to set a date and time for your virtual quiz and share with your friends and family so they can make a donation.
Remember to make sure that they do not donate anonymously, so you can send them the link to join the quiz online!
Get Started
Step 1: Create a fundraiser account on Virtual Quiz Events. It takes less than five minutes to do and is really easy.
Step 2: Pick the time and date of your quiz and set the registration amount. You can give the quiz a name that friends and family will recognise, so they can find your quiz when you invite them. If you want, there is also the option to write about why you want to hold the quiz for Beat and how the donations will support our services.
Step 3: Let Beat know what you've got planned so we can help you make it a huge success.
Step 4: Invite your friends and family to join online! Email, message or text friends and family to let them know about the date, time and name of your quiz. You can even share a Facebook event and invite friends and family to join too, sharing the link on the event page.
Step 5: Organise a virtual catch up before and after the quiz, so you can discuss team names and see how you got on!
Step 6: There will be cash prizes from a percentage of the registration for those who come in 1st, 2nd and 3rd place. The remaining 60% of registration will be transferred to you so that you can make the donation to Beat. Once we receive your donation we can get a digital certificate out to you to share with everyone who joined!
If you have any questions or would like any help setting up your quiz, email and we'll be happy to help.
Please follow our Fundraising Guidelines to ensure your fundraising is suitable, legal, and safe for everyone involved.


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NORFOLK (AP) -- The Navy has finished construction on the largest solar energy project in Virginia.
The Virginian-Pilot reports the 10-acre solar farm just outside of Naval Station Norfolk contains more than 8,600 panels.
Michelle Perry, project manager for Naval Facilities Engineering Command, says the panels can generate up to 2.1 megawatts of electricity, which is enough to power about 200 homes. That's about 2 percent of the electricity required to run Naval Station Norfolk, the world's largest naval base.
Although construction was completed in November, the photovoltaic panels are not yet connected to the electricity grid that feeds the base. Perry says that connection is expected by Christmas.
Information from: The Virginian-Pilot, _URL_


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Arbor Day – The Selflessness Of Trees
Arbor Day, as it is commonly known today, is of American origin and was first observed in Nebraska, USA on the 10th of April 1872. Now it is always observed on the last Friday in April. Arbor Day in different forms and names is now observed in more than fifty countries. Arbor in Latin means a tree. The spirit of Arbor Day is to plant trees and care for them and help them grow strong. It is what we give back to nature.
If we think about our ancestors, we can imagine the dependence on trees in those times. Trees were widely used for wood, fruits, flowers and the shade a tree gave. The earliest humans derived tremendous benefits from the trees. We are all obliged to trees. Can birds survive without trees? Think of a tree.
Most of the trees grow from a small seed. Let us become a little philosophical. The seed makes a tree and the tree gives so many more seeds, who in turn give so many trees and in turn more seeds. How many trees does a seed contain? Infinite. Is this not an exciting thought? The trees stand alone on a piece of land. The roots go deep down the earth and hold the soil strongly. The tree gives leaves, wood, bark, fruits, flowers, sometimes different types of gums and shade for the tired souls. A tree gives all that it has got back to the animal world. In deep jungles, so many animals rest below the trees in the afternoons, and the birds make countless nests on the trees. Can one imagine the importance of trees in the ecological balance? It can not be measured.
The butterflies know about that than many of us humans. Many of us have seen so many trees since our childhood that we never give a thought to them. Visit a desert and you will realize the blessing that are trees. The desert looks so desolate without any growth, without the trees. Where are the singing birds in a desert? Where are the fruits, the flowers, and the shade? Trees are necessary for our growth, and they tell us about a selfless life. After you plant a tree and help it grow, it asks nothing from you for its lifetime. It only gives. That is the selflessness of trees and that is how a life must be lived by all of us. Give more and expect less in return.
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$ as a Lie group, to see that its associated Lie algebra is (isomorphic to) $gl(n, \mathbb{R})$, an essential step is to get the equivalence of tangent planes $T_e(GL(n,\mathbb{R})) \cong T_e(gl(n,\mathbb{R}))$ (where $e$ is the neutral element). But this is trivial if we have in mind that $GL(n,\mathbb{R}) = \{A\in gl(n,\mathbb{R}) : det(A) \neq 0 \}$ and that $det$ is continuous, because then $GL(n,\mathbb{R})$ is automatically an open set of $gl(n,\mathbb{R})$.
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For the reasons of reputation points, I am unable to comment on KConrad's post. I up-voted his response, however, because he does make a great point about the Muir book(s). This one in particular is of great interest if you have any thoughts as to wondering why determinants (and development of them) was/is important:
The Theory of Determinants in the Historical Order of Development
I've gone through parts and it's dry, but thorough.
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Are there other books by Muir on determinants? – Mariano Suárez-Alvarez Aug 18 '10 at 21:38
Mariano: he has a book on determinants and then this history book comes in multiple volumes. – KConrad Aug 18 '10 at 21:41
From the realm of probability there are determinental and permanental processes. Terry Tao has a nice post about determinental processes here. For instance
"Examples of processes known to be determinantal include non-intersecting random walks, spectra of random matrix ensembles such as GUE, and zeroes of polynomials with gaussian coefficients."
I've not worked with these processes myself but I've heard enough seminar talks using them to say there is plenty of interest out there.
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Just an example from applied statistics where determinants are unavoidable (because they are used to define the relevant concepts. In design of experiments, one wants to choose "optimal" values of the regressor variables $x_1, \dots x_p$ used to estimate a linear regression model $Y=X \beta + \epsilon$, where $X$ is the design matrix, an $n \times (p+1)$ matrix with the first column consisting of ones, and row $i$ being the covariates used for experimental run $i=1, \dots, n$.
D-optimality defines the optimal design to be the one maximizing the determinant $\det X^T X$, under the practical restriction that the regressor values x's must belong to some set where the experiment is feasible to do.
One way of justifying this is that the requirement is equivalent to minimizing the volume of confidence ellipsoids, calculated under the normal model. Mostly, numerical optimization is used to construct such designs. (although there are many theoretical papers solving toy models).
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The area of an arbitrary triangle is most easily computed from its vertex coordinates as a 3x3 determinant (no square roots, trig, etc.). This generalizes to 3D (volume of a tetrahedron) and higher dimensions.
The cross product of two vectors a,b (essential tool in mechanics) is easily understood and memorized once one observes that its coordinates are 2x2 minor determinants of a 2x3 array formed by a and b. This too generalizes and provides a definition for cross product of n-1 vectors in n dimensions.
More generally, determinants combined with homogeneous coordinates are all one needs to derive elegant formulas for the basic operations of n-dimensional projective geometry, such as plane through 3 points, intersection of 3 planes. They also provide a coordinate representation (Pluecker coordinates) for lines in 3-space, or more generally for k-dim subspaces of n-dim prijective space.
The sign of the determinant of a matrix tells whether the rows are a leftor right-handed frame, and whether the corresponding linear map preserves or reverses orientations.
Determinants are more efficient than Gaussian elimination to compute the inverse of a 2x2 or 3x3 matrix, perhaps even 4x4. Unlike standard G.E. these formulas do not require division and may require fewer bits per number in intermediate results.
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PS. The area of a polygon with n vertices is easily computed as the sum of n-2 determinants of 3x3 matrices. This too generalizes to higher dimensions: the volume of a polyhedron with n triangular faces is the sum of n-3 deetrminants of 4x4 matrices. Similarly for the measure of a d-dimensional polytope with n simplicial facets. Note that the polygon/polyhedron/polytope does not have to convex or even simply connected, and it is not necessary to partition it in non-overlapping triangles/tetrahedra/simplices. – Jorge Stolfi Sep 25 '12 at 20:37
I quickly scanned the answers and didn't find the following:
Square matrices of order $n$ can be considered to be embedded in $\Bbb R^{n \times n}$. The determinant is a continuous function of the entries of the matrix, so the singular matrices are $\det^{-1}(0)$ and are therefore a closed set in $\Bbb R^{n \times n}$. Thus, there will be non-singular matrices arbitrarily close to a singular matrix in any convenient metric on $\Bbb R^{n \times n}$. Of course, they will have pretty ugly condition numbers.
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1) The Chern-Weil theory of characteristic classes is built upon determinants of functions of curvature forms of vector bundles. 2) Feynman path integrals require determinants (but typically in infinite dimensions).
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In the diagram below, tangentis perpendicular to diameter at. is the intersection of with the circle.
is a diameter with,,, and all collinear. If the measure of is more than the measure of, what is the measure of in degrees?
Lethave measure and measure. Thus.
is a diameter, so arcs and add up to. Therefore,
Combined with we can solve for and. Thus measures.
The correct answer is: 34
Can someone please explain how to get 180 - (90 + x) = 2y?


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Starting with Windows Server 2012 R2, it is possible to re-size a Virtual Hard Disk for a running Virtual Machine on Hyper-V! It was not possible to do so before for an online Virtual Machine running on Windows Server 2012 and earlier Hyper-V versions.
Let's have a look at some of the benefits this feature offers and requirements before you dive in and use it.
The re-sizing feature allows expanding or shrinking a Virtual Machine hard disk while the Virtual Machine is running. Storage administrators can avoid downtime to perform virtual hard disk maintenance tasks and there is no impact to end users. Users can still access Virtual Machine and its volumes. This feature reduces the maintenance costs associated with downtime of critical Virtual Machines.
There is also a Resize-VirtualDisk PowerShell cmdlet available which can be used to script the re size operation on multiple virtual hard disks quickly. There is no need to use or enable any component to use this feature. This functionality is available out of the box using "Edit Virtual Hard Disk" wizard.
Since it is a feature of Hyper-V running on Windows Server 2012 R2, make sure to perform this task on a Windows Server 2012 R2 Hyper-V Server. You must also be using a VHDX format and this must be connected to a SCSI controller before you can expand or shrink a Virtual Hard Disk. However, Disk type can be fixed, differencing or dynamic.
So, let's see how you actually Expand and Shrink virtual hard disks without powering off Virtual Machines. I'm not going to explain the step-by-step process but provide you the necessary screenshots for your understanding.
How to Expand?
To expand, Right Click on the Virtual Machine and then click on "Settings". Click on the Virtual Hard Drive you want to extend in the "Settings" page. Note:You cannot extend/compact a Virtual Machine hard drive if a snapshot exists. A warning message will be shown stating that "Edit is not available because checkpoints exist for this Virtual Machine". This is also shown in the red circle of the below screenshot.
Next click on "Edit" button to launch the "Edit Virtual Hard Disk" wizard as shown below:
Click "Next" to select "Expand" action as shown below:
Specify the size of the virtual hard drive to expand and then click on Finish.
At this point, Virtual Machine hard disk size has been expanded, now you need to launch "Disk Manager" in Virtual Machine and then use the "Extend the Volume" wizard to make un-allocated space available to the Virtual Machine. When you open "Disk Manager", you will see the expanded size as un-allocated space as shown in the below screenshot of the Virtual Machine:
Right Click on the volume you want to extend and then select "Extend Volume" wizard as shown in the below screenshot and then follow the on-screen steps to complete the process.
How to Shrink?
To shrink the storage capacity, you must first initiate the "shrink" action from within the Operating System of Virtual Machine using "Disk Manager". Using the "Disk Manager", Right Click on the volume you want to shrink and then select "Shrink Volume" action as shown in the below the screenshot:
Note: "Extend Volume" action is available only if you have un-allocated space available in the Operating System. Next, specify the amount of space you want to shrink as shown below and then hit "Shrink" button:
Once shrunk from within the Operating System of Virtual Machine, initiate the final shrink action using the "Edit Virtual Machine" wizard. Click on "Edit" button on the Virtual Machine's setting page to specify the new size for the virtual hard disk as shown in the below screenshot. "Edit Virtual Machine"wizard will not allow you to specify the new size value lesser than the size being used by the Operating System inside the Virtual Machine. As you can see in the below screenshot, the C: volume is about 58.6 GB in size and "Edit Virtual Hard Disk" wizard also specifies the minimum required size which is 60 GB. This is shown in the red circles in the below screenshots:
Once you have specified the size to shrink, click "Finish" button for VMWP.exeto process the change and reduce the size of the VHDX file on the Host storage.
- Does not work on virtual hard disks using VHD format.
- The re-sizing feature does not work on Virtual Hard Disks which are attached to IDE Controllers.
- Does not work for Virtual Hard Disks which have snapshots/checkpoints associated.
- Expanding and Shrinking process is not visible to the Virtual Machine Operating System. You must take some extra steps.
- Once the virtual hard disk has been expanded, the extra space is shown as un-allocated in the Disk Manager in the Operating System of the Virtual Machine. You must make the extra space available to Virtual Machine by using the "Extend Volume Wizard" within the Disk Manager of the Virtual Machine.
- Shrinking reduces the storage capacity of the Virtual Hard Disk. If you want to shrink the size, you must use the "Disk Manager" in Operating System of the Virtual Machine. Finally, use the "Edit Virtual Hard Disk" wizard to reduce the size of the virtual hard disk.


text:
Speed Control and Position Estimation of Small Hydraulic Cylinders for Digital Clay Using PWM Method
Book, Wayne John
MetadataShow full item record
Digital Clay is a new generation 3D computer input and output device for surface shape and haptic effects. The device consists of arrays of fluidically actuated cells under the control of valves connected to two pressure reservoirs in a manner ultimately suitable to an implementation in MEMS technology. At the current stage, it is very difficult to implement a tiny position sensor into the tiny cell. This paper presents a control method for the speed and position estimation and control for the cells of digital clay only using low cost pressure sensors and without using any position-sensing device.


text:
|Oracle Enterprise Manager Database Tuning with the Oracle Tuning Pack
Part Number A86647-01
The Outline Management tool allows you to manage stored outlines directly using a GUI-based tool. Specifically you can browse, sort, delete, and edit outlines with this tool. Outlines are preserved by Oracle's plan stability functionality, so before using Outline Management or Outline Editor to create or edit an outline, it is important to understand how plan stability works. Plan stability prevents certain database environment changes from affecting the performance characteristics of applications. Such changes include changes to the optimizer statistics, changes to the optimizer mode settings, and changes to parameters affecting the sizes of memory structures, such as
BITMAP_MERGE_AREA_SIZE. Plan stability is most useful when you cannot risk any performance changes in an application.
An outline consists primarily of a set of hints that is equivalent to the optimizer's results for the execution plan generation of a particular SQL statement. When you create an outline, plan stability examines the optimization results using the same data used to generate the execution plan. That is, Oracle uses the input to the execution plan to generate an outline, and not the execution plan itself.
As mentioned above, an outline is a means for modifying optimizer behavior. When the optimizer encounters the SQL text of the outline, it applies the supplied hints. The plans Oracle maintains in stored outlines remain consistent despite changes to a system's configuration or statistics. Using outlines also stabilizes the generated execution plan if the optimizer changes in subsequent Oracle releases. Plan stability facilitates migration from the rule-based optimizer to the cost-based optimizer when you upgrade to a new Oracle release.
For more information on plan stability, see the Oracle9i Database Performance Guide and Reference.
There are two ways to launch the Outline Management Tool:
The Outline Management tool provides an easy-to-use graphical interface for managing your stored outlines. The tool can tell you how many outlines exist in the database and whether or not the outlines have been used since the last database upgrade.
Specifically, the tool allows you to:
The Outline Management Tool can also be used to launch the Outline Editor to create a new outline or edit an existing outline. When you want to create a new outline, Outline Management gives you two options: Create and Create Like. The Create feature launches the Outline Editor which allows you to specify the name, category, and SQL text for your new outline. Use the Create Like feature to make a new outline similar to an existing one.
When you edit an existing outline, the Outline Editor lets you to see the SQL text and modify the graphical explain plan for the outline. For more information on using the Outline Editor, see Chapter 26, "Introduction to the Outline Editor".


text: PARTISANS have designed Grotto, a sauna located on San Souci Island, in the Georgian Bay area of Ontario, Canada. Grottos, historically, have been known as natural or artifi cial caves that are embedded deep behind the curvature of streams, and thus discovered by those who would take the time to explore. As a free-standing sauna, the Grotto uses two high performance ovens that ensure efficiency and control. There are vents and fans in-place that allow the building to breathe seasonally and prevent rot or mold in the structure. The rest of the systems were based on controlled air flow. "We used insulation on the building to not only protect its components from heating up or cooling down too quickly, but also to make the Grotto more energy efficient. The specific type of wood, Cedar, was then selected based on a number of factors; such as resistance to rot, aroma, colour, local sources, and quality. Furthermore, the internal structure of the Grotto was tightly sealed and a layer of energy efficient aluminum foil was adhered to all internal surfaces creating a convective air plenum between the internal wood panels and the space in which they were mounted. This allows for the wood to expand and contract evenly with even heat movement all around. The space behind the wood panels created convection currents that allow the skin to breathe through the ventilation pores that were carved into seats and seams of the cedar panels. The result is a sculpted space, a sensual experience, and a sophisticated exercise in building science." Photography by Jonathan Friedman and PARTISANS.


Dictionary Results for beacon
1. beacon - noun
· a fire (usually on a hill or tower) that can be seen from a distance
Synonym(s): beacon_fire
Hypernym(s): visual_signal
2. beacon - noun
· a radio station that broadcasts a directional signal for navigational purposes
Synonym(s): radio_beacon
Hypernym(s): radio_station
3. beacon - noun
· a tower with a light that gives warning of shoals to passing ships
Synonym(s): lighthouse, beacon_light, pharos
Hypernym(s): tower
4. beacon - verb
· shine like a beacon
Hypernym(s): shine, beam
5. beacon - verb
· guide with a beacon
Hypernym(s): lead, take, direct, conduct, guide
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Word Unscrambles for :cucho lsbnlhue cncieulm iissr
Rhymes for :stidham importantly implausible margory
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_family = "") +
 theme(panel.grid.major.x = element_blank(),
 panel.grid.major.y = element_line(colour="grey", size=0.5),
 legend.title = element_text(size = 16, face = 'bold'),
 axis.text = element_text(size = 16),
 axis.title = element_text(size = 16),
 legend.text= element_text(size=16),
 axis.line = element_line(colour = "black")) # Achsen etwas dicker
# save 650 x 800
Inspect population shares of classes
If you are interested in the population-shares of the classes, you can get them like this:
[1] 27.92 40.13 31.95
or you inspect the estimated class memberships:
 1 2 3
158 234 185
 1 2 3
27.38 40.55 32.06
Ordering of latent classes
Latent classes are unordered, so which latent class becomes number one, two, three... is arbitrary. The latent classes are supposed to be nominal, so there is no reason for one class to be the first. You can order the latent classes if you must. There is a function for manually reordering the latent classes: poLCA.reorder()
First, you run a LCA-model, extract the starting values and run the model again, but this time with a manually set order.
_TAG_ starting values from our previous best model (with 3 classes)
_TAG_-run the model, this time with "graphs=TRUE"
lc<-poLCA(f, mydata, nclass=3, probs.start=probs.start,graphs=TRUE, na.rm=TRUE, maxiter=3000)
# If you don't like the order, reorder them (here: Class 1 stays 1, Class 3 becomes 2, Class 2 becomes 1)
new.probs.start<-poLCA.reorder(probs.start, c(1,3,2))
_TAG_ polca with adjusted ordering
lc<-poLCA(f, mydata, nclass=3, probs.start=new.probs.start,graphs=TRUE, na.rm=TRUE)
Now you have reordered your classes. You could save these starting values, if you want to recreate the model anytime.
This is the poLCA-standard Plot for conditional probabilites, which you get if you add "graph=TRUE" to the poLCA-call.
It's in a 3D-style which is not really my taste. I found some code at dsparks on github or this Blog, that makes very appealing ggplot2-plots and did some little adjustments.
lcmodel <- reshape2::melt(lc$probs, level=2)
zp1 <- ggplot(lcmodel,aes(x = L1, y = value, fill = Var2))
zp1 <- zp1 + geom_bar(stat = "identity", position = "stack")
zp1 <- zp1 + facet_grid(Var1 ~.)
zp1 <- zp1 + scale_fill_brewer(type="seq", palette="Greys") +theme_bw()
zp1 <- zp1 + labs(x = "Fragebogenitems",y="Anteil der Item-\nAntwortkategorien", fill ="Antwortkategorien")
zp1 <- zp1 + theme( axis.text.y=element_blank(),
zp1 <- zp1 + guides(fill = guide_legend(reverse=TRUE))
If you want to compare the items directly:
zp2 <- ggplot(lcmodel,aes(x = Var1, y = value, fill = Var2))
zp2 <- zp2 + geom_bar(stat = "identity", position = "stack")
zp2 <- zp2 + facet_wrap(~ L1)
zp2 <- zp2 + scale_x_discrete("Fragebogenitems", expand = c(0, 0))
zp2 <- zp2 + scale_y_continuous("Wahrscheinlichkeiten \nder Item-Antwortkategorien", expand = c(0, 0))
zp2 <- zp2 + scale_fill_brewer(type="seq", palette="Greys") +
zp2 <- zp2 + labs(fill ="Antwortkategorien")
zp2 <- zp2 + theme( axis.text.y=element_blank(),
zp2 <- zp2 + guides(fill = guide_legend(reverse=TRUE))


text:
Converter rated power
I am new to HOMER and currently I am simulating Wind/PV/Grid system and comparing it to the actual system that has been built. I have a couple of questions to ask:
1. I noticed that the the wind turbine never reaches its rated power of 500 kW. I am wondering why this happens? In real condition, the wind turbine reaches its rated power at least 10% of the time.
2. Also, I've put 0-1750 KW (as the actual system size) in the search space for solar converter but in the optimisation results, HOMER always suggests 1400 KW converter. Is there any way to change this? I am trying to get simulation results as close as possible to the actual system.
1) a) The wind turbine output depends on the available wind resource and the wind power curve. Make sure, in the power curve, you have defined the wind speed for the rated power. You can find the power curve in the wind turbine design section.
b) Make sure the wind resource has the wind speed that corresponds to rated power.
2) Since you have mentioned a range of sizes (0-1750 kW) for the converter, HOMER chooses the optimal size required as per the PV output produced. If you want a fixed converter size(s), instead of mentioning the range in HOMER optimizer, you can mention specific sizes in the search space. For example, mention 0,500,1000, 1500,1750 in the search space to consider all these sizes. Hope this helps.
Thank you for your suggestions. I've put 1750 Kw in the converter search space and it worked.
I've also updated the wind turbine power curve and have made sure the wind speed in the wind resources exceed the wind speed corresponding to the rated power. However the simulation results were still the same i.e. it never reaches the turbine rated power. It reaches its rated power only when the turbine losses are zero, which is of course impossible. Do you have another suggestion I could try?
I have looked at the windspeed data and it seems some of it is high enough to generate the rated power even after accounting for losses. Here are the HOMER file and the actual wind speed data. FYI, there are two wind turbine Enercon E-48 (500 kW) and 3 Vestas V-52 (850 kW, total 2.55 MW) which all never reach their rated power. I hope you can give me advice on this. Thank you very much.
(wind speed data)
The rated capacity of the wind turbines are 800 kW and 850 kW. However high the wind speeds maybe, under ideal conditions ('0' loss factor), the maximum power that the turbines can produce are 800 and 850 kW. You have mentioned about 9.63% as turbine losses. So the maximum output of the turbines will definitely be lesser than the rated output. Getting rated output from the turbines is an ideal situation.


text:
The Tec Trimix 65 Course with DIVE KAWARTHA
This course opens up the advantages of trimix to the diver, and divers are qualified to make multi-stop decompression dives that employ EANx and oxygen for accelerated decompression, and any trimix with an oxygen content of 18% or more.
They can dive to a maximum depth of 65 metres/210 feet.
What You'll Learn
The PADI Tec Trimix 65 course is intended to extend the depth range of technical divers already trained and qualified to use air, enriched air and oxygen for technical decompression dives beyond 50 metres /165 feet.
This course is for Tec 50 divers (or those holding a qualifying certification from another training organization). The course extends your depth range capabilities by training you to use trimix (a blend of helium, oxygen and nitrogen).
- Plan and execute at least five dives using EANx and trimix blends
- Use decompression software to create custom dive tables and dive plans
- Make training dives as deep as 65 metres/210 feet
Scuba Gear You'll Use
- Double cylinders (minimum 12 litre/70 cubic feet each, with larger preferred) with isolator manifold
- Primary and secondary regulators, one with two metre/seven foot hose (approximately) for gas sharing, and one with SPG
- Stage/decompression cylinders with regulator, SPG, mounting hardware and proper labeling/markings. Two per diver will be required
- Backup decompression cylinders as appropriate and required for the environment
- BCD and harness – redundant buoyancy control is required (double bladder BCD or dry suit if suitable for weight of equipment worn)
- Depth gauge/computer and backup depth gauge/computer
- Timing device and backup timing device
- Trimix decompression information (tables/trimix computer) and backup decompression information
- Exposure suit appropriate for environment and dive duration. (If you use a dry suit, you should be trained/experienced with its use in recreational and technical diving prior to using it for trimix training or diving.)
- Argon dry suit inflation or other inflation system as needed
- Weight system (if needed)
- Jon line (if needed for current diving environments)
- Inflatable signal tube
- Lift bag (bright yellow or per local community practice preferred)
- Dive knife / cutting device and backup slate, backup mask (optional)
- Compass, lights (optional)
- Drift kit (if drift decompressing)
Learning Materials You'll Need
Tec Trimix Diver Crew-Pak which includes all required materials, including: manual, deep stop calculation table, trimix decal and emergency procedures slate.
Topics covered include:
- Trimix diving depth ranges
- Exposure planning
- Selecting a mix
- Argon inflation systems
- Handling three or four decompression cylinders
- Decompression models
- Emergency procedures
- Face masks and multi-gas computers.
To purchase this product, contact us.
- Be a PADI Rescue Diver (or hold a qualifying certification from another organization and having proof of CPR and first aid training with the previous two years).
- Be certified as a Tec 50 (or hold a qualifying certification from another organization)
- Be at least 18 years old
- Have logged at least 100 dives
- Have a medical form signed by your physician.
- Contact us to take the Discover Tec Diving experience.
- Ask a Scuba Expert
- Download a scuba medical questionnaire (PDF)
No Courses Found


text:
Invaders or endemics? Molecular phylogenetics, biogeography and systematics of Dreissena in the Balkans
Article first published online: 5 JUN 2007
Volume 52, Issue 8, pages 1525–1536, August 2007
How to Cite
ALBRECHT, C., SCHULTHEIß, R., KEVREKIDIS, T., STREIT, B. and WILKE, T. (2007), Invaders or endemics? Molecular phylogenetics, biogeography and systematics of Dreissena in the Balkans. Freshwater Biology, 52: 1525–1536. doi: 10.1111/j._PHONE_.2007.01784.x
- Issue published online: 5 JUN 2007
- Article first published online: 5 JUN 2007
- (Manuscript accepted 28 March 2007)
- ancient lakes;
- Balkan Peninsula;
- invasive species
1. Zebra mussels and their relatives (Dreissena spp.) have been well studied in eastern, central and western Europe as well as in North America, because of their invasiveness and economic importance. Much less is known about the biology and biogeography of indigenous (endemic) taxa of Dreissena, in the Balkans. A better knowledge of these taxa could help us (i) understand the factors triggering invasiveness in some taxa and (ii) identify other potentially invasive species.
2. Using a phylogenetic approach (2108 base pairs from three gene fragments), Dreissena spp. from natural lakes in the Balkans were studied to test whether invasive Dreissena populations occur in such lakes on the Balkan Peninsula, whether Dreissena stankovici really is endemic to the ancient Lakes Ohrid and Prespa, and to infer the phylogenetic and biogeographical relationships of Balkan dreissenids.
3. No invasive species of Dreissena, such as Dreissena polymorpha, were recorded. The supposedly 'endemic'D. stankovici is not restricted to the ancient Lakes Ohrid and Prespa, but is the most widespread and dominant species in the west-central Balkans. Its southern sister taxon, Dreissena blanci, occurs sympatrically with D. stankovici in Lakes Prespa, Mikri Prespa and Pamvotis. Both species are classified into the subgenus Dreissena (Carinodreissena) of which the subgenus Dreissena (Dreissena) (which includes the invasive D. polymorpha) is the sister taxon. Dreissena blanci and D. stankovici are considered to represent distinct species.
4. On a global scale, the two Balkan species have small ranges. An early Pliocene time frame for the divergence of the subgenera Carinodreissena and Dreissena is discussed, as well as potential colonization routes of the most recent common ancestor of Carinodreissena spp.
5. The ambiguous taxonomy of dreissenids in the Balkans is addressed. As nominal D. blanci presbensis from Lake Prespa has nomenclatural priority over D. stankovici, the correct name for the latter taxon should be Dreissena presbensis.


text:
Over 50,000 Costume and Textile Artifacts
The costume and textile collection at the Museum spans the breadth of Chicago's history and is particularly strong in materials from the late 19th century to the present. The Museum's extensive designer collection, ranging from Charles Worth gowns to the innovative designs of Yohji Yamamoto, has earned an international reputation.
Made in Chicago
Many artifacts in the Museum's collection were made by Chicago's dressmakers, milliners, and manufacturers. Future collecting will also focus on Chicago's once-thriving garment industry.
From George Washington to Michael Jordan
The costume collection has a number of items worn by prominent Chicagoans and Americans. These include objects belonging to Abraham and Mary Todd Lincoln, Michael Jordan's basketball uniform, and Mahalia Jackson's choir robe. The earliest pieces include suits worn by George Washington and John Adams.
Clothing as Historical Artifact
New emphasis on the significance of clothing as historical artifacts has increased interest in the collection. Recent acquisitions include clothing documenting 19thand 20th-century work attire, such as uniforms of nurses, police officers, flight attendants, and a bell hop, as well as clothing from Chicago's immigrant communities.


Top tips for avoiding Chinese customs delays
According to the Foreign & Commonwealth Office, the value of UK exports to China have quadrupled between 2002 and 2012 and now stand at more than £12.5 billion, annually.
Any delivery into China has to go through Chinese Customs, and with that in mind, cross-border courier firm ParcelHero has put shared it's top three tips for avoiding customs hold-ups when sending shipments to China.
1: List each item on the Customs Invoice
The Customs Invoice or Customs Document is a crucial part of the customs clearance process for parcels to China. Customs Invoices should detail the items you are sending, their individual value and the reason you are sending them. The biggest mistake senders can make is to not list each item on the Customs Invoice.
ParcelHero's Head of Public Relations, David Jinks, says: "Many people will simply declare the contents of their parcel using one word, such as "Gift". They are unaware that Chinese Customs need more information about what is actually being shipped. When information is missing from the invoice it causes clearance delays. It's important to remember that Customs are a government authority and their rules are final and not negotiable.'
2: Provide valid contact details for the receiver
Chinese Customs authorities will contact your receiver as part of the Customs clearance process. This is a standard clearance protocol as China has extensive import regulations. The receiver or recipient of your parcel may be required to provide additional information to Chinese Customs. This could be an import licence, or confirmation of the reason for import. Therefore it's extremely important that you provide a valid telephone number and email address for your receiver in China when you book your parcel online. If customs are unable to contact your receiver then they will not be able to clear the goods for delivery.
3: Be aware of the Customs import regulations
Each country has different rules and regulations for what you can and cannot import. People are often unaware that they are responsible for ensuring the items they send to China are actually permitted for import into the country. Some items are prohibited, whilst other items may have specific restrictions in place in terms of quantities or values, so it's really important customers check the import rules and regulations for China prior to shipping. It's too late to check the rules after you have sent your parcel, and this could result in fines applied by Customs, or return shipping charges if your parcel is to be sent back.
goatChinese New Year will be celebrated around the world this week, as the Year of the Horse makes way for the Year of the Goat on 19 February.
The Year of the Goat is also referred to as the Year of the Sheep, and although this has led to some disagreements, it is generally accepted that both are names for the lunar new year. The symbol for the new year is 'yang' which can be used to refer to any sheep or goat.
According to some superstitions, most people born in the year of the sheep, or goat, will lead unhappy lives. Other superstitions around Chinese new year say that if you want to be lucky, you mustn't wash your hair on the first day of the new year, and you should wear red undies. Make of that what you will.


text:
November 9, 2011 Leave a comment
Begin in 3ds Max by drawing the outline of your mesh. Users typically load an image that that they used for creating an RPC into the background and trace it using splines. Don't worry about the size. This is determined at the time the RPC is created. Be sure and close the spline.
I have created an outline of the pumpkin from October's blog and create a shape to represent the base of the RPC. The tip of the triangle depicts the front of the RPC. Right click on these and select Convert to editable mesh.
Once I have created the shapes for my RPC's mesh I arrange them the way the final mesh will look.
To export the mesh, select the geometry to be exported and then click on the 3ds Max icon (File button), Export then Export Selected. Choose AutoCAD *.DXF as the file type when naming the file. Choose the option for Selected Objects and click on OK.
At this point a.DXF file should be successfully created, however we will need to convert this into a.msh file to use it with RPC Creator. This can be performed by using the Convert to RPC Icon Tool. This file can be downloaded here:
Once installed open the Convert to RPC Icon Tool and select the.DXF file just generated and then select a name and creation path for the RPC Icon Mesh file that will be created. Click on Convert and the.msh file will be created.
This is the file that will be used during the RPC Creation process. Select the custom mesh option and then browse for this file.
When the RPC is added to a scene it will now have a mesh representation prior to rendering so that a better example is given of what the actual rendered object will look like. Custom meshes save RPC users the time necessary to have to reposition objects that could have been placed more accurately using this technique.


Sometimes you may need to alter the design to join together two nets that are currently separate.
Unless you are creating a PCB design 'on the fly', you should not really be trying to connect two nets here. Instead you should switch back to your Schematic, make the change there, then use Forward Design Changes to push the change forward to the PCB.
However, if you are creating a PCB design directly without a corresponding Schematic, you can use the Add Connection or Add Track commands to connect those items together.


Rudolf Schuster
Name: Rudolf Schuster
Occupation: World Leader
Gender: Male
Birth Day: January 4, 1934
Age: 86
Country: Slovakia
Zodiac Sign: Capricorn
Social Accounts
Rudolf Schuster
Rudolf Schuster was born on January 4, 1934 in Slovakia (86 years old). Rudolf Schuster is a World Leader, zodiac sign: Capricorn. Nationality: Slovakia. Approx. Net Worth: Undisclosed.
He and Ukrainian President Viktor Yuschenko were two of the most unpopular candidates to seek re-election in the history of their respective countries. In his 2004 re-election campaign, Schuster received just over seven percent of the total vote; Yuschenko earned an even lower percentage following his own campaign.
Net Worth 2020
Find out more about Rudolf Schuster net worth here.
Height Weight Hair Colour Eye Colour Blood Type Tattoo(s)
Before Fame
Early in his political career, he served as Mayor of the Slovakian city of Košice.
Biography Timeline
Schuster's father's family is of Carpathian German origin, while his mother's family is of Hungarian origin. Rudolf Schuster was married in 1961 to Irena Trojáková (died 2008) and he has two children (son Peter and daughter Ingrid) and two granddaughters. In his private life, he is a sports fan, a traveller and a writer. He is also a camera fan.
In 1998 he founded the centre-left Party of Civic Understanding (SOP – Strana občianskeho porozumenia).
In 1999 he received honorary citizenship from Miskolc, as recognition of the good cooperation between the city and Košice during his mayorship.
In 2004, Schuster sought re-election in the 2004 presidential election and received 7.4% of the votes.
🎂 Upcoming Birthday
Currently, Rudolf Schuster is 87 years, 7 months and 1 days old. Rudolf Schuster will celebrate 88th birthday on a Tuesday 4th of January 2022.
Find out about Rudolf Schuster birthday activities in timeline view here.
Rudolf Schuster trends
 1. Who is Rudolf Schuster?
 2. How rich is Rudolf Schuster?
 3. What is Rudolf Schuster's salary?
 4. When is Rudolf Schuster's birthday?
 5. When and how did Rudolf Schuster became famous?
 6. How tall is Rudolf Schuster?
 7. Who is Rudolf Schuster's girlfriend?
 8. List of Rudolf Schuster's family members?
 9. Why do people love Rudolf Schuster?


room. This is a form of importance sampling, also called importance driven final gathering. We also subdivide anytime there are significant differences between neighbors to reduce noise, this is called adaptive sampling. NumAdaptiveRefinementLevels controls how many refinement levels there are, AdaptiveBrightnessThreshold controls how big of a neighbor difference there must be to refine a sector.
As to the Lightmass WorldSettings options, IndirectLightingSmoothness operates on the settings in step 4), the amount of irradiance cache smoothing.
IndirectLightingQuality increases the number of samples and depth of refinement in steps 5-7, the final gathering.
Sky light method (assuming static skylight, stationary is a bit different):
 1. The sky light HDR texture is exported to Lightmass as an 3 band spherical harmonic, which you can think of as an extremely low resolution cubemap (2x2 on each face approx). So if you have a very bright spot in the sky cubemap it will be spread out over a large region. This is basically prefiltering to avoid noise.
 2. We do a mini final gather at each lightmap texel and compute sky lighting with a very low number of rays. This is cached on the surface and will become the first bounce of skylight GI once the final gather accesses it.
 3. During the final gather, any rays that hit the scene look up the cached sky direct lighting from step 2), which now becomes first bounce sky lighting. Any rays that miss the scene and hit the background lookup from the sky SH, this is sky direct lighting. We refine the final gather based on brightness differences between sectors of the hemisphere, but no importance sampling is done because we don't have any photons from the sky.
So now you can see why static sky lights have limited quality and only support one indirect lighting bounce. This is something we could improve, but it's a lot of work and complexity. Specifically, we should actually export a cubemap to Lightmass, and do importance sampling of the cubemap's contents (trace more rays to the brighter texels).
This is pretty much Chinese to my hear but I'm happy to see devs interested in improving lightmass for arch-viz users!
You may have a potentially HUGE market in sight because everybody in arch-viz communities are talking about real-time/Unreal. I think eventually we all want to go real-time!
This is where I would like to get to in Unreal - not sure it's possible? It's just an HDRI and a Sun in Blender/Cycles render engine. There is some post processing in Photoshop.
What kind of method cycles use for G.I? path tracing?
Heh, maybe I got too technical.
Short answer - not without some significant work on our part. Pure HDRI quality is lacking. But I hear you guys loud and clear, that's how you want to light (as opposed to directional or spot lights).
while we're talking about lightmass…is there a way (or is it planned, even possible) to calculate lighting for just selected objects? for example, if we add single object/move or add a light, the engine tells us how many objects need their lightmaps calculated. if the engine can tell that, why not enable lighmaps calculations only for affected geometry? it would speed up things even further instead of waiting another hour and a half for light calculation to finish for the whole level when only one object was added…
These explanations are spot on (Made so many things easy and this is the minimum information required to understand lightmass). Till you guys made HDRI Lighting awesome in unreal engine, kindly let us know how to resolve some common issues which come when we simulate HDRI lighting with added support of Punctual lights.
Link to download above scene file - Dropbox - Error
Thanks Raghu, I'll take a look at that scene when I get a chance, hopefully monday.
It's possible, although a fair amount of lightmass processing (editor export, lightmass import, photon mapping) have to be done no matter what you want to build. Only the blue part in the Swarm visualizer (double click the swarm icon hiding in the taskbar when building lighting). It's not something we have planned just due to not enough time though.
My two cents
99% of the time I notice that if you go over a value of 2-3 on the "Indirect light intensity" ( on the main sun light I mean ) you'll have those light leaks all over.
I usually use, to boost up the intensity of the interiors, a skylight with a limited amount of intensity ( 0.2/0.5 ) and 1-2 of Indirect lighting.
Then bounce cards all over the place.
_USER_: +1 Raghu, to be able to build the lighting only for certain object will be a godsend, since if you're working on different environments and you just want to test part of the scene it'll be great to process only a portion of that or if you move some objects just reuild the lighting for those ( and the affected surfaces of course )
Okay, thank you. At least I know not to try and transfer my techniques over to Unreal and just work with what it gives me. Sure would be nice to be able to light scenes this way though. :slight_smile:
A workaround for that, which is what I am doing in my current project is organize the scene outline on different parts. I have exterior yard, ground level and level 1. As now I am working only on the level 1 I simply select all actors which are grouped in a folder from exterior yard ( easier if you arrange by type so you can only select static meshes) and simply set to movable and all the lights to not affect world. They will be ignored in lightmass. Might not be as easy as having an option like you mentioned ( which I also hope will be implemented at some point ) but does the job of lowering the building time.
I did some quick tests
 - I used "Static Lighting Level" 0.07 and "Indirect Lighting Smoothness 1.3"
 - It's possible to achieve the same lighting quality from vray
 - Kola's work it's pretty much the same as Alex Roman's vray works. The secret is in the
 shaders and the contrast. In the lighting pass you will definitely spot a lot of lighting errors. Even
 in Alex Roman's work, you can see lighting erros from Irrmap + LC solution. Darkness is our best friend
 in this case.
 - Here is a nice article for understanding better the photomapping process :
Have a nice study!


Take the 2-minute tour ×
Hi: I'm trying to sort a list of tuples in a custom way:
For example:
lt = [(2,4), (4,5), (5,2)]
must be sorted:
lt = [(5,2), (2,4), (4,5)]
* b tuple is greater than a tuple if a[1] == b[0]
* a tuple is greater than b tuple if a[0] == b[1]
I've implemented a cmp function like this:
def tcmp(a, b):
 if a[1] == b[0]:
 return -1
 elif a[0] == b[1]:
 return 1
 return 0
but sorting the list:
lt show me:
lt = [(2, 4), (4, 5), (5, 2)]
What am I doing wrong?
share|improve this question
I see nothing wrong, except that given your input and comparison function, your initial list is already sorted. – Ignacio Vazquez-Abrams Dec 29 '10 at 12:38
... And what if a[1] == b[0] AND a[0] == b[1]? What if neither is the case? – Karl Knechtel Dec 29 '10 at 13:12
add comment
6 Answers
up vote 2 down vote accepted
I'm not sure your comparison function is a valid one in a mathematical sense, i.e. transitive. Given a, b, c a comparison function saying that a > b and b > c implies that a > c. Sorting procedures rely on this property.
Not to mention that by your rules, for a = [1, 2] and b = [2, 1] you have both a[1] == b[0] and a[0] == b[1] which means that a is both greater and smaller than b.
share|improve this answer
Sorry, I've not explained it very well. In my data set, not exists the case (1,2) and (2,1) at the same time. Really the numbers are state id's, and the tuple is a transition representation, i.e. (2,3) means, state(2).next() == 3. – Antonio Beamud Dec 29 '10 at 12:53
_USER_: still, without "normal" behavior from the comparison function (such as transitivity) you cannot expect the sort to work properly – Eli Bendersky Dec 29 '10 at 12:59
You're right. I'm reviewing all the problem. A lot of thanks. – Antonio Beamud Dec 29 '10 at 13:01
add comment
Sounds a lot to me you are trying to solve one of the Google's Python class problems, which is to sort a list of tuples in increasing order based on their last element.
This how I did it:
def sort_last(tuples):
 def last_value_tuple(t):
 return t[-1]
 return sorted(tuples, key=last_value_tuple)
EDIT: I didn't read the whole thing, and I assumed it was based on the last element of the tuple. Well, still I'm going to leave it here because it can be useful to anyone.
share|improve this answer
add comment
You can write your own custom key function to specify the key value for sorting.
def sort_last(tuples):
 return sorted(tuples, key=last)
def last(a):
 return a[-1]
tuples => sorted tuple by last element
 - [(1, 3), (3, 2), (2, 1)] => [(2, 1), (3, 2), (1, 3)]
 - [(1, 7), (1, 3), (3, 4, 5), (2, 2)] => [(2, 2), (1, 3), (3, 4, 5), (1, 7)]
share|improve this answer
add comment
You could also write your code using lambda
def sort(tuples):
 return sorted (tuples,key=lambda last : last[-1])
so sort([(1, 3), (3, 2), (2, 1)]) would yield [(2, 1), (3, 2), (1, 3)]
share|improve this answer
add comment
Your ordering specification is wrong because it is not transitive.
Transitivity means that if a < b and b < c, then a < c. However, in your case:
(1,2) < (2,3)
(2,3) < (3,1)
(3,1) < (1,2)
share|improve this answer
well, really (1,2) < (2,3), and yes, the problem is about graphs, and this a cycle. Really in my dataset doesn't exists cycles. Anyway, you are right :) – Antonio Beamud Dec 29 '10 at 12:57
_USER_ Beamud Oh, I switched < and > from your example. Corrected. However, comparison functions must be transitive, because that allows the sorting routine to take shortcuts (like compare a,b and b,c and never a,c). The cycle is just used for proving that your comparison function is wrong. – phihag Dec 29 '10 at 13:03
add comment
Try lt.sort(tcmp, reverse=True).
(While this may produce the right answer, there may be other problems with your comparison method)
share|improve this answer
add comment
Your Answer


What hydrogen Car? - Mazda RX-8 hydrogen RE
Article 5 of 5 See all
 - What is a hydrogen car?
 - How does it work?
 - What kinds are there?
Mazda was leasing hydrogen-powered cars in Japan as long ago as 2006, but the company is now also heavily involved in Norway's national hydrogen project (HyNor), which has been set up to test hydrogen in the transport sector in Norway.
HyNor is building an initial hydrogen infrastructure, as part of a future permanent set-up, so that it will be possible to drive hydrogen-fuelled vehicles along the 580km route between Oslo and Stavanger.
As part of its commitment to the project, Mazda has developed a dual-fuel RX-8 coupe that can run on both hydrogen and petrol.
Mazda admits that such an engine is not as efficient as a fuel cell, but because it shares so much with the conventional petrol engine, the development costs are much lower, and there are fewer issues with reliability.
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DevOps – Vagrant Training – 5 Days
Course Description – Onsite Vagrant Training
In this Vagrant training course, you will learn the core concepts of Vagrant, how to use Vagrant in your organization, how to properly configure Vagrant, how to use Vagrant commands to provision virtual servers, and how to use plug-ins to extend the functionality of Vagrant.Vagrant is an open source virtualization tool and is closely coupled with the DevOps methodology. Mostly used by developers and system administrators, Vagrant automates the provisioning of virtual servers. With automation, Vagrant eliminates the errors that occur with manual tasks. Automation also allows an almost unlimited number of virtual servers to be created instantaneously.
 - Introduction to Vagrant
 1. What does Vagrant do?
 2. Vagrant benefits to developers, administrators, and designers.
 3. Vagrant Alternatives
 1. Desktop Virtualization
 2. Containers
 - Cloud
 1. Vortex
 1. Configuring the Vagrant Environment
 1. Installing Virtual Box
 2. Installing Vagrant
 - Dealing with installation problems
 1. Vagrant without VirtualBox
 - Setting up your first Vagrant Machine
 1. Getting all the components up and running
 2. Using the Vagrant configuration file
 3. Using Boxes (Concepts)
 4. vagrant up
 5. Using the Vagrant Machine
 1. Vagrant machine state
 2. Using SSH
 - Shared file system
 1. Understanding basic networking
 2. Vagrant Teardown
 - Suspending
 - Halting
 - Destroying
 3. Rebuild
 - Providers
 - Command Line Interface
 1. box
 2. connect
 3. destroy
 4. global-status
 5. Vagrant environment variables
 - Vagrant Share
 1. Http sharing
 2. Allowing SSH access through SSH sharing
 3. Using Vagrant Connect
 4. Custom Provider
 - Vagrant VM provisioning
 1. Concepts and setup
 1. Understanding the concept of automated provisioning
 2. Supported provisioners
 2. Setting up Apache Tomcat
 3. Automated provisioner basics
 1. Running shell scripts
 2. Chef Server
 - Puppet
 1. Using multiple provisioners (or no provisioners)
 2. Platform specific provisioning issues
 1. Linux
 2. Windows
 - Networking
 1. Basic Usage
 2. Forwarded Ports
 3. Private Network
 4. Public Network
 5. Host only networking
 6. Bridged networking
 - Synced Folders
 1. Basic usage
 2. NFS support
 3. Using rsync on a guest machine
 4. Using the SMB synced folder type
 5. Virtual Box
 - Creating Multimachine Clusters
 1. Defining multiple machines
 2. Controlling multiple machines
 3. Multimachine communication
 4. Designating a primary machine
 5. Autostart machines
 - Boxes (Practice)
 1. Usage of Boxes
 2. Box Format
 3. Creating Boxes
 1. From an existing environment
 2. From scratch
 4. Box management
 - Extending Vagrant
 1. Basics of Plug-Ins
 2. A basic Plug-In example
 3. Basics of Plug-In development
 4. Development commands
 5. Plug-In configuration issues
 6. Adding new guest OS detection (Optional)
 7. Guest capabilities (Optional)
 8. Adding host detection (Optional)
 9. Adding new host capabilities (Optional)
 10. Supporting new providers (Optional)
 11. Adding new provisioners (Optional)
 12. Distributing your Plug-In (Optional)
From Wikipedia: Vagrant is an open-source software product for building and maintaining portable virtual software development environments, e.g. for VirtualBox, Hyper-V, Docker, VMware, and AWS. The core idea behind it lies in the fact that the environment maintenance of virtualizations becomes increasingly difficult in a large software development project. Vagrant simplifies the necessary software configuration management in order to increase development productivity. Vagrant is written in the Ruby language, but its ecosystem supports development in almost all major languages.
Other courses to explore:
Ansible Configuration and Administration Training – Onsite, Custom, Lowest Price
DevOps Workshop – Onsite, Custom, Lowest Price
DevOps Boot Camp – Onsite, Custom, Lowest Price
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text:
Blunt Family History
Blunt Name Meaning
nickname for someone with fair hair or a light complexion, from Anglo-Norman French blunt 'blond' (Old French blund, blond, of Germanic origin). nickname for a stupid person, from Middle English blunt, blont 'dull', 'stupid' (probably from Old English blinnan 'to stop', or Old Norse blundr 'sleep').
Source: Dictionary of American Family Names ©2013, Oxford University Press


Are first person shooters healthy for kids?
Asked by: Sofias4
 - Not necessarily healthy but not negative
 Many video games including first person shooters help kids strenghthen hand eye coordination skills. But the problem is kids aren't really supposed to play them in the first place, most fps games are rated mature and there's a reason for that so if you don't want your child exposed to violence then don't give them access to the game.
 - Yes, if Done Well
 While it is true that many major titles like Call of Duty or Battlefield are arcade-like and not representative of reality, other games like Arma or Red Orchestra 2 are more accurate. It's not like the glorification of war is exclusive to video games; it has been in every form of entertainment media to date. I can't even begin to count the number of movies that fit the bill. Some games like Spec Ops: The Line actually provide really insightful commentary on war. Others are outright shy down by critics from the community for being too accurate.
 - Not healthy for kids
 It makes the kids want to be like the people in the game. Have you ever heard the stories about those kids shooting people? The rate of kids killing people are rising and i think it is because of games like these. I would let my kid play these games until he was probably 15
 - No, they are not
 No they are not healthy to kids for a number of reasons (not to say that there are no positive aspects to these games), firstly they give kids a false sense of what real war is like and therefore desensitize them to that kind of thing, secondly its gives them false ideas about the physical limits of the human body (in no way am i saying this applies to all kids, but mostly younger ones), for example healing quickly after being shot, being able to be shot with multiple bullets and still survive and lastly i must say that this definitely does not apply to all kids, but it does to the majority of them, so no, i do not think that they are exactly healthy for kids.
 - No, not healthy.
 First person shooters aren't exactly "bad" for kids, they provide entertainment and there's no evidence to support that they negatively affect mentally stable children. However, they're not "healthy". A child who plays fps's isn't going to be any healthier, mentally, emotionally, or physically, than a child who doesn't. Playing shooters isn't hurting children, but it's not improving their health.
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text:
Applicants should have: A good first degree, typically 2.1 or above in a related subject. • Students who do not have English as their first language must have an IELTS score of 6.0 or above in all skills or an equivalent rating in another recognised language testing system. • Each application is considered on its own merits, so entry requirements may vary.
Months of entry
The School of Engineering has a population of around 50 MPhil/PhD students working in seven research groups. This work is supported by research funding of around £1.6 million per annum.
Each student normally first enrols on the MPhil degree. After completing the first year of the MPhil, the student's progress is reviewed, and, if considered satisfactory, the student is permitted to transfer to the PhD for a further two to three years of research. A student who does not wish to continue at this point may write up and submit the work to be considered for an MPhil degree.
MPhil/PhD students are usually provided with two supervisors, who guide them through the research. The supervisors are usually research staff from within the Faculty, although a supervisor may be appointed from another Department or from outside the university. There are seven engineering research groups focusing on practical and important real-life problems. The Faculty also offers a one-year MSc by Research.
Recent topics include:
- The Wolfson Centre for Bulk Solids Handling Technology
- The Manufacturing Engineering Research Group
- The Mobile and Wireless Communications Research Laboratory
- The Internet Security Research Laboratory
- The Centre for Innovative Product Development
- The Infrastructure Management Research Group
- The Sustainability in Civil Engineering Research Group
Please note: If your research area does not fall exactly into one of the following categories, contact the us to discuss your requirements.
Qualification and course duration
Course contact details
- _PHONE_ 9000


text:
Crane motion induces payload oscillation that makes accurate positioning of the payload a challenging task. As the payload size increases, it may be necessary to utilize multiple cranes for better control of the payload position and orientation. However, simultaneously maneuvering multiple cranes to transport a single payload increases the complexity and danger of the operation.
This thesis investigates the dynamics and control of dual-hoist bridge cranes transporting distributed payloads. Insights from this dynamic analysis were used to design input shapers that reduce payload oscillation originating from various crane motions. Also, studies were conducted to investigate the effect input shaping has on the performance of human operators using a dual-hoist bridge crane to transport distributed payloads through an obstacle course. In each study, input-shaping significantly improved the task completion time. Furthermore, input-shaping control greatly decreased operator effort, as measured by the number of button pushes needed to complete a task. These results clearly demonstrate the benefit of input-shaping control on dual-hoist bridge cranes.
In addition, a new system identification method that utilizes input shaping for determining the modal frequencies and relative amplitude contributions of individual modes was developed to aid in the dynamic analysis of dual-hoist bridge cranes, as well as other multi-mode systems. This method uses a new type of input shaper to suppress all but one mode to a low level. The shaper can also be used to bring a small-amplitude mode to light by modifying one of the vibration constraints.


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Network Access Control (NAC)
Security for networks with IoT
An introduction to NAC
What is Network Access Control (NAC)?
Network access control, or NAC, is a zero-trust network access solution that provides users with enhanced visibility into the Internet of Things (IoT) devices on their corporate networks.
This technology has been around for nearly two decades, but a new generation of its solutions is helping organizations keep up with today's ever-expanding attack surface, delivering not only visibility of the network environment, but also enforcement and dynamic policy control. Whether devices are connecting from inside or outside the network, it can automatically respond to compromised devices or anomalous activity.
How NAC Secures Your Network
A properly functioning solution can deny access to noncompliant users or devices, place them in quarantine, or restrict access to a small number of network resources, separated from the rest of the network. NAC generally supports the following:
 1. Authentication and authorization of users and devices
 2. User and device profiling
 3. Denial of unsecured devices
 4. Quarantine of unsecured devices
 5. Restricting access to unsecured devices
 6. Policy lifecycle management
 7. Overall security posture assessment
 8. Incident response through policy enforcement
 9. Guest networking access
Network Access Control Benefits and Use Cases
IoT and BYOD
There are now billions of non-traditional compute, IP-enabled devices that are connecting to networks. (This means basically everything on the network that isn't a laptop or mobile phone, from IP cameras, to VoIP phones, printers, HVAC controls, temperature sensors, badge readers, digital displays, bluetooth sensors, and many more examples.)
Incident Response
The role of NAC in incident response is often significant. Solutions can be configured to automatically enforce security policies, share contextual information, and isolate unsecure devices from accessing other parts of a network.
Healthcare is an industry rapidly embracing the Internet of Medical Things (IoMT) and now many new networked devices are coming online to support advances in medicine and medical care. But as more medical devices access the corporate network, it is critical to employ NAC solutions that can help protect devices and massive troves of sensitive personal data, including medical records. This can help improve healthcare security overall and keep medical facilities and other healthcare institutions safe from ransomware and other prevalent threats.
FortiNAC: Network Access Security Solution
FortiNAC is the Fortinet network access control solution. It enhances the overall Fortinet Security Fabric with visibility, control, and automated response for everything that connects to the network. It provides protection against IoT threats, extends control to third-party devices, and orchestrates automatic responses to a wide range of networking events.
FortiNAC enables three key capabilities to secure IoT devices:
 - Network control to limit where devices can go on the network
 - Deliver agent and agentless scanning of the network for detection and classification of devices
 - Use a centralized architecture for easy deployment and management
 - Enforce dynamic access control
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Control and Application Server
Each server manages up to 2,000 ports in the network
Control and Application Server
Each server manages up to 15,000 ports in the network
Control and Application Server
Each server manages up to 25,000 ports in the network
Management Server
See datasheet for details
Endpoint Visibility and Auto Provisioning
Device Count
100, 1K, 10K, or 50K concurrent endpoint device per license
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Below are answers to common questions regarding FortiNAC and related services:
How does FortiNAC identify a new device on the network?
FortiNAC uses the network characteristics of the device to classify the devices. There are up to 20 different attributes and techniques that FortiNAC can utilize such as Vendor OUI and DHCP fingerprinting, to profile a device.
Does FortiNAC analyze device behavior (EUBA) to identify a device?
No, FortiNAC does not perform behavior analysis but does collect network data about a device, utilizing up to 20 methods to profile a device.
Do I need a FortiNAC in every location?
No, FortiNAC's architecture enables complete visibility even from remote locations. There are many organizations that deploy FortiNAC in a cloud such as Amazon Web Services (AWS) to provide NAC for their network.
What is the upper limit of how many devices FortiNAC can support?
There is no upper limit for how large a network can be. The FortiNAC servers can be stacked and managed as a group.
What form factor does FortiNAC come in?
The FortiNAC solution requires a server to run the Control and Application functions. Those can run in one server for smaller deployments while larger organizations might need several servers. Severs can be either hardware appliances or Virtual Machines (VMs). Licenses that run on the servers determine the level of functionality of the solution.
What are the most popular form factor?
The VM form factor is most commonly deployed.
Do you need a server at each location?
No, the architecture of FortiNAC means that you can centrally deploy and provide coverage for several sites. FortiNAC is not sniffing the traffic directly, so it does not need to be on the network. This greatly enhances FortiNAC's ability to scale to multi-site locations.
What are the different license levels for FortiNAC?
FortiNAC offers three levels of capability:
 - Base - offering visibility and network lockdown (does not permit new devices to join without permission)
 - Plus - offering the Base capabilities and adds user identification and segmentation.
 - Pro - offering the Plus capabilities and add automatic response
Can you move from one license level to another? Or do you have to buy a whole new license?
Fortinet offers upgrade FortiNAC licenses so that if you want to move from Base to Plus, or Plus to Pro, you can simply buy the upgrade license.
Are the FortiNAC licenses incremental in their features? Do you need to buy Base if you buy Pro?
No, the FortiNAC licenses are all-inclusive so you only need to purchase the level that you want.
Are the FortiNAC licenses subscriptions?
FortiNAC licenses are offered in both perpetual and subscription forms.
Are the license measured by user?
No, the licenses are counted by active port or wireless device. For example, if you have 300 users in your network, but only 100 are active at any one time, you only need licenses for 100 active ports.
Are the FortiNAC licenses shared across locations?
Yes, when deployed with a Management Server, the FortiNAC licenses can be shared across the locations, as well as across stacked servers.
Does FortiNAC do end-user behavior analysis (EUBA)?
No, FortiNAC does not perform behavior analysis but does collect network data about a device, utilizing up to 20 methods to profile a device. When deployed with a FortiGate, ForitNAC can use the traffic sensing capabilities in the FortiGate to watch for anomalies in traffic patterns.
How does FortiNAC protect against MAC-spoofing if it does not do EUBA?
FortiNAC can protect