text:
Islamiat Class 9 Notes Chapter 5, 6, 7, 8, 9
Islamiat Class 9 Notes Chapter 5, chapter 6, chapter 7, chapter 8, and chapter 9 short quesiton.
Islamiat Chapter 5 (Zakat Obligation, Importance, and Distribution
Q.1) What is Zakaat? Who are under obligation to pay Zakaat?
ZAKAAT:
Zakat means making something pure by removing harmful substances. It also means to get nourished or grow. In religion it means to purify the wealth by giving away its certain percentage as charity to the poor. The Holy Prophet (PBUH) described Zakaat as wealth taken from the rich and given to the poor. Zakaat is also called poor rate or poor tax. Technically it is an annual tax for the imposed on the rich people and is paid to the poor. It is accumulated as a surplus at the expiry of full one year.
OBLIGATION:
Zakaat is a compulsory religion tax imposed on any person who is sane, free, adult and a Muslim provided that his property or income is to the extent of Nisab. Nisab is someone's minimum fixed property or income on which Zakaat is due and which has been in his profession for their period of one complete year. Zakaat is payable not only on cash but also on jewellery, gold, silver, animals, agricultural land, crops and all kinds of commercial goods. The Nisab or fixed amount of property upon which Zakaat is due varies according to the kind of property in possession.
Q.2) Write a brief note on the importance of Zakaat.
IMPORTANCE OF ZAKAAT:
Zakaat occurs thirty-two times in Holy Quran. With the exception of few verses, it has been mentioned with Salaat. Zakaat is obbe of four practical articles of Islam. The other three articles of Islam are prayers, fasting and Hajj. Thses three articles benefit no one but the person who performs them, but Zakaat which is also an act of worship benefits mankind. It brings prosperity to the giver in this world, and he will also get a good reward in the Hereafter. No to Zakaat is a great sin.
The importance of Zakaat is evident from an event. Once some persons came to the Holy Prophet (PBUH) and made a request to tell them about the teachings of Islam. The Holy Prophet (PBUH) mentioned the two commands of Allah- prayers and Zakaat. Thus he made it clear that sfter prayers, the most important act of worship is to pay Zakaat.
After the Holy Prophet (PBUH) passed away, some people refused to pay Zakaat. Thereupon Hazrat Abu Bakr Siddique (RA) declared Jihad against them. The Holy Quran has warned in harsh words, the persons who do not pay Zakaat. Allah says:
"O you who believe! Indeed there are many among the rabbits (Jewish) and priests who devour the wealth of mankind in falsehood, and dissuade them from the way of Allah. And there are those who hoard up gold and silver and spend it not in the way of Allah. Announce unto them a very painful punishment. On the Day of Judgement this gold and silver will be heated in the fire of hell, and with it will be branded their f0reheads, their flanks and their backs and it will be said unto them."
This is the treasure which you hoarded for yourselves. Now taste of what you hoarded for yourselves.
Zakaat provides man with the best opportunity to work for the welfare of people. Zakaat supports the poor and deprived persons of a society. It is helpful to replace the feelings of hatred and vengeance with the sentiments of sympathy, reverence and mutual love. Zakaat purifies the heart from the love for wealth and fills it with the desire to fulfil the wish of God. The Zakaat prayer begins to love the poor. The payment of Zakaat causes wealth to come into circulation. Thus the financial condition of the members of society gets improved.
Read more: Islamiat 9 class Notes Chapter 4 Bodily purification
Q.3) State the heads of expenditure for the distribution of Zakaat in the light of the teachings of the Holy Quran.
DISTRIBUTION OF ZAKAAT:
The Holy Quran has laid down the following heads of expenditure for the distribution of Zakaat. The Holy Quran says:
" The alms are only for the poor and the needy, and those who collect them, and those whose hearts are to be reconciled and to free the captives and the debtors and for the cause of Allah, and for the wayfarers: a duty imposed by Allah. Allah is Knower, Wise."
In the quoted verse of the Holy Quran there are the following eight heads of the expenditure for Zakaat:
1. The poor
2. The needy
3. Collectors of Zakaat (the employees of Zakaat Department)
4. Those whose hearts are to be reconciled who have recently accepted Islam.
5. Captives
6. Debtors
7. for the cause of Allah
8. The travellers
For giving away Zakaat , the close relations should be given preference over those who are not blood relations. Some people despite being poor, do not apt to begging. They have a keen sense of honour and self-respect. Such people should be traced and given away Zakaat and other amounts of charity.
Q.4) What warning has given to the people who do not pay Zakaat?
WARNING OF ALLAH:
The Holy Quran has warned in harsh words, the persons who do not pay Zakat. Allah says:
"O you who believe! Indeed there are many among the rabbits (Jewish) and priests who devour the wealth of mankind in falsehood and dissuade them from the way of Allah. And there are those who hoard up gold and silver and spend it not in the way of Allah. Announce unto them a very painful punishment. On the Day of Judgement this gold and silver will be heated in the fire of hell, and with it will be branded their f0reheads, their flanks and their backs and it will be said unto them."
Islamiat Class 9 Notes Chapter 6 (Forbearance and gratitude)
Q.1) Why does Islam teach the believers to keep patience in the adverse circumstances?
Islam teaches the believers to keep patience and self control in the worst circumstances because a true believer shows a positive conduct and that is the conduct of forebearance. It refrain from doing or saying something in such a manner that shows one's patience and self control. Instead he remains steadfast and resolute in utter distress and has absolute trust in God.
Q.2) what is its importance according to the Quran and Sunnah?
GRATITUDE:
Gratitude means the feeling that you want to thank and praise someone because of the favour and kindness he has done to you. A grateful person expresses his feeling of gratefulness in acknowledgment of the favours he has received from someone. It is Allah Who most of all deserves acknowledgment and thankfulness for the countless favours and unlimited kindness that He showers on mankind.
IMORTANCE:
The Holy Quran has greatly emphasized the importance of gratitude. The people who feel gratitude for the favour of Allah are blessed with the prosperity. The Holy Quran says:
" If you give thanks, I will give you more."
Prophet Sulaiman said, as stated in the Quran:
"This is by the Grace of my Lord to test me whether I am grateful or ungrateful! And whoever is grateful, truly, his gratitude is for (the good of) his own self, and whoever is ungrateful, (he is ungrateful only for the loss of his own self). Certainly! My Lord is Rich (Free of all wants), Bountiful"
Allah says:
"And (remember) when your Lord proclaimed: 'If you give thanks (by accepting Faith and worshipping none but Allah), I will give you more (of My Blessings); but if you are thankless, verily, My punishment is indeed severe"
Therefore, make thanking Allah part of morning and evening remembrances (adhkars) to get more of Allah's blessings in our lives.
The Prophet (PBUH) said,
"Whoever is not grateful to the people, he is not grateful to Allah."
"A grateful eater will have a reward like that of a patient fasting person."
Islamiat Class 9 Notes Chapter 7 (The importance of family life)
Q.1) What is the family life and what is its importance?
FAMILY LIFE AND ITS IMPORTANCE:
Family life means a group of people who are related to each other, especially parents and their children. A person, lives his life with his family. The members of a family are attached to each other due to different relationships. The human civilization also started with the family system which is essential for its very survival. Thus in a way the family is an essential part of society. A society has also its influence on the families. If a society is moving on the path of prosperity and Islamic ways of life, the families will also proper and lead a virtuous life. Islam has greatly emphasized the importance of a strong family system in human society. According to Islam 'Zaujain' (husband and wife) are the two important pillars of a family.
Q.2) What is the base of the family life and what is its chief objective?
BASE OF FAMILY:
Marriage provides a lawful base of family life between two members of a pair. Almighty Allah says:
"It is He (Allah) Who created you from one soul, and from this soul He created its pair so that it may get solace."
As a result relationship between husband and wife comes into existence. The Holy Quran has described the martial relationship as 'Ehsab' which means fortification or to be safe by building strong walls all around. In other words, after marriage Zaujain (husband and wife) become safe from immoral attacks. They become life partners and share each other's comfort and suffering. They sympathize each other without any selfish ends and help each other to solve their difficulties and problems. Marriage increases the mental capabilities of the partners and enables them to think over their family problems wisely. With the birth of children the mutual relationship between the parents is further strengthened and homes becomes a paradise.
CHIEF OBJECTIVE:
According to the Islamic point of view the chief objective of the family life is to ensure the continuance and reproduction of human race. The bond of marriage is the only way to keep the family life pure and chaste. The family system therefore serves as the foundation of a society. When this very foundation is destroyed, it will not be possible to organize a society and save it from turmoil and disorder.
Allah Almighty has given very clear instructions for the stability and continuance of the family life. in Holy Quran Allah says:
'And among His signs is this: He created for you helpmates from yourselves so that you might find comfort in them, and He has put between you (your hearts) love and mercy."
The relationship between husband and wife brings satisfaction to the human instinct on the one hand, and creates mutual love, trust and compassion on the other. The two partners are follow-travellers on the path of life due to spiritual relationship.
Q.3) How is the family system related to society?
The bond of marriage is the only way to keep the family life pure and chaste. The family system therefore serves as the foundation of a society. When thsi very foundation is destroyed, it will not be possible to organize a society and save it from turmoil and disorder.
Q.4) What are the rights and duties of Zaujain (husband and wife)?
RIGHTS AND DUTIES OF ZAUJAIN:
Islam has given equal rights to the husband and the wife. The Holy Quran says:
"And the women have rights similar to those of men over them in kindness."
Of Zaujain, the rights of one partner are the duties of other partner, and the duties of one partner are the rights of other partner.
RIGHTS OF WIFE / DUTIES OF HASBAND:
According to the Islamic teachings it is the duty of the husband to provide food and shelter to the family. He should make arrangements for housing, clothing and feeding his wife and children. He should bear expenses of the necessities of life according to his economic status. He should allow her wife to keep the amount, given to her as Mehr, in her possession or invest it in some business. He should treat his wife kindly. He should fear God and do justice and favour to his wife. He should also acknowledge her right to inheritance according to the Islamic Shariah and should not do injustice to her.
RIGHTS OF HUSBAND /DUTIES OF WIFE:
It is the foremost duty of a wife to love her husband and give him comfort. In the Holy Quran Allah says:
"So good women are the obedient, guarding in secret."
A wife should also be faithful to her husband. It is her duty to guard all the things entrusted to her by her husband. She should not disclose his secrets and should not leak out the household affairs. She should also guard her husband's honour and nobility.
The life of the Holy Prophet (PBUH) is the lighthouse which guides us to right path. He says:
"Amongst you the best one is he who is the best for his family" and amongst you i am best for my family."
The Holy Prophet (PBUH) also said: "The best among the wife is the one who is obedient and a source of delight for her husband when he is present and guardian of his wealth and of her own self when he is absent."
Q.5) What are the rights and duties of children and parents?
RIGHTS AND DUTIES OF CHILDREN AND PARENTS:
The rights of children are the duties of the parents and rights of parents are the duties of children.
RIGHTS OF CHILDREN/ DUTIES OF PARENTS:
Islam enjoins on the parents to fulfil the rights of their children. In the Holy Quran Allah Almighty says:
"O believers! Save yourselves and your families from the fire (of hell)."
It is the duty of the parents to make arrangements for upbringing, educating and training their children in the best possible manner. They should also make arrangements for their marriage. They should maintain equity and justice among their children. Even after the death of their parents, the righteous offspring cause addition to their virtues.
The Holy Prophet (PBUH) said, "One who is not affectionate to Allah's creatures and to his own children, Allah will not be affectionate to him."
RIGHTS OF PARENTS/ DUTIES OF CHILDREN:
It is the duty of children to obey every order of their parents except that which requires them to show disobedience to God. Children should treat their parents kindly and respectfully and should give importance to their opinion. Especially when parents attain old age, the children should respect their feelings and treat them with love and kindness. They should find time everyday to attend their old parents. When the parents pass away the children should pray for their salvation.
The Holy Quran says:
"We have enjoined on man kindness to the parents."
"Show kindness to parents. If one of them or both of them attain old age in your life, say not a word of contempt to them, nor repel them, and speak to them a gracious word. And lower to them the wings of submission out of kindness and say: My Lord! Have mercy on them as they brought me up when i was a little child."
The status of mother is higher than the father because she undergoes more suffering for the sake of her children. The Holy Quran says:
"His mother bears him in weakness upon weakness and his wearing is in two years."
There is a saying of Holy Prophet (PBUH), "Heaven is beneath the feet of mother."
Q.6) What is the importance does Islam give to relatives?
IMPORTANCE OF RELATIVES:
Islam requires us to do good and to be kind to our relatives. According to the Holy Quran, after parents our other blood relations deserve most to be helped and treated kindly by us.
"Worship none but Allah, and show kindness to parents and relatives."
The importance of doing to relatives is evident from the following sayings of the Holy Prophet (PBUH).
"A person who does not respect the rights of his relatives will not enter Paradise."
"One who break off his relations with his relatives shall not enter Paradise."
"Giving of alms to relatives carries two rewards: one is the reward of alms and the other is the reward of helping relatives."
Islamiat Class 9 Notes Chapter 8 (Hijrat and Jihad)
Q.1) What is Hijrat? Write a brief note.
HIJRAT:
Hijrat means the act of migrating from one place to another especially in order to live or find work. In Islamic terminology, Hijrat means the migration of the Muslims from one place to another for the religious cause. If in a certain country the Muslims are Subjugated and oppressed, they are subjected to torture for adopting the Islamic way of life, they must leave that place and migrate to somewhere else. However, if they are unable to migrate due to lack of resources or they are too helpless to migrate, then it is likely that Allah will forgive them.
Allah commands in Surah Nisa:
"When angels take the souls of those who die in sin against themselves, the angels will ask: In what plight were you? They will reply: We were weak and oppressed in the earth. The angels will say: Was not the earth of God spacious enough for you to migrate therein? Such men will find their abode in hell, an evil refuge. Except those men, women and children who are really weak and appressed or who have no means in their power nor do they have any guide to direct their way. For such people it is likely that Allah will forgive them. And Allah is Merciful and Forgiving. And who migrates in the cause of Allah, will find in the earth many a refuge and abundance in the earth. And one who forsakes his home for Allah and His Messenger, and death overtakes him, his reward is incumbent due on Allah. And Allah is ever Forgiving, Most Merciful."
The above verses of the Holy Quran make it clear that Hijrat benefits a Muslim in this world and in the Hereafter.
Q.2) What is Jihad?
JIHAD:
Jihad in an Arabic word derived from 'Juhd' or 'Jahd' means endeavor, effort or struggle. In Islamic terminology it means to exercise all types of physical and mental energy in the way of God. Jihad requires the believers to sacrifice wealth, families, blood relations and even their own lives for the supremacy and spread of the true religion. Those who take part in Jihad do their best to make the designs of the enemies ineffective and check their attacks. The believers do not withhold from fighting if it becomes inevitable to save the religion. That is why Jihad has been declared a great worship in Islamic teachings.
The sense of Jihad is very clear. According to some theologians the best kind of Jihad is Jihad bin-nafs. According to some theologians such a type Jihad is Jihad-e-Akbar! It means that one should be willing and prepared to bear all the physical tortures in the services of the religion of Allah. The Holy Quran and some traditions of Holy Prophet (PBUH) give importance to this kind of Jihad. The Holy Quran says:
"And those who strive for us, We will surely guide them to Our paths, and verily Allah is with the good."
Q.3) what are the types of Jihad mentioned in the Holy Quran? Explain each type in detail.
TYPES OF JIHAD:
According to the Holy Quran there are two types of Jihad.
1. Jihad bin-Nafs
2. Jihad bil-Mal
1. JIHAD BIN-NAFS:
Jihad bin-Nafs is the Jihad by the person which means that a Muslim should be willing and prepared to bear all kinds of physical troubles in the services of the religion of Almighty Allah. One must be prepared to undergo hardship or to be sentenced to death. He must not fear arrows, spears, swords, guns or cannons. He must be prepared to receive injuries and cuts which may take even his life. When we use word Jihad it usually means Jihad bin-Nafs. In the Holy Quran the word 'Qital' is used for this type of Jihad.
Allah commands te Muslims to make preparations for Jihad, and forbids Muslims to use the word 'dead' for the martyres. The Holy Quran says that the martyres receive sustenance from their Lord and they hold festivities. Allah has promised a great reward to them.
2. JIHAD BIL-MAL:
Jihad bil-Mal or Jihad by wealth means that one has to spend one's wealth or property for the preaching of religion and for the success of Truth. Almighty Allah gives man wealth and property so that he may spend it in the way of Allah. The Holy Quran says:
"Those who believe and migrated and did Jihad in the way of Allah, by wealth and by person, they are exalted to high rank by Allah."
On the other hand those who hoard up wealth and do not spend it in the way of Allah, they have been warned of the severe punishment. The Holy Quran says:
"Those who hoard up gold and silver and do not spend it in the way of Allah, Allah will give them the 'good news' of Painful punishment."
There are two major hindrances in the way of success and progress. The first is the love for one's self and other is the love for wealth. The nation which sets aside these hindrances and spends its wealth and manpower without any hesitation gains success.
Islamait Class 9 Notes Cha 9 Rights of People and Human Relations
Q.1) Describe the rights of people in the light of Seerah – e- Prophet (PBUH)?
RIGHTS OF HUMAN BEINGS
If genuine rights of every individual are granted to all the individuals they can devote their talent and energy for the uplift of society with perfect peace of mind. In this way, the homogeneous social environment is the feeling of discontent and unrest arises which damages the social orders and destructive tendency paralyses the constructive capability of the members of the society. Therefore, a true Muslim is always concerned with the rights of human beings as particularly as the rights of Allah. He considers himself equally accountable for the rights of human beings before Allah.
RIGHTS OF SERVANTS
Allah has enjoined equal rights to all His beings and no one is superior on the basis of his wealth, colour or caste. Similarly, the servants are to be treated:
with kindness and love, keeping in mind that they are also the creation Allah as we are. Their basic needs and necessities of their life should also be fulfilled as long as they stay with us. We should treat them the way we war: ourselves to be treated. Servants should be forgiven for the mistakes they encounter and should never be hurt. The Holy Prophet was extremely kind to his slaves. He used to say;
"They are your brothers; give them to what you eat; give them to wear what you wear".
THE RIGHTS OF NEIGHBOURS
Neighbours enjoy certain rights in our lives which we are obliged to fulfil living near each other's house, it is our responsibility to share their sorrow and happiness. The prophet said:
"The one who believes in Allah and the Last day should do good to his neighbours".
In daily life, a person has to deal with his neighbours. Therefore, the rights of neighbours have been greatly emphasised. There are three kinds of neighbours who deserve special treatment.
i) Neighbours who are relatives.
ii) Non-relative neighbours (even if they are non-Muslims).
iii) Temporary relationship with colleagues in the same profession or individuals travelling together.
Some of the traditions regarding the rights of neighbours are reproduced below:-.
a) A person who eats while his neighbour is hungry is not a believer.
b) A person who is good and kind to his neighbours holds a superior position among you.
c) If a neighbour needs your help, help him; If he asks for a loan; give him; if he is a. destitute, give him financial assistance; if he falls ill, arrange for his treatment.
THE RIGHTS OF THE PARENTS
In a Society, a person gets maximum help and assistance from his parents. Parents are not only responsible for bringing a person in this world but they are also responsible for his upbringing and education. Only parents sacrifice their comforts and belongings for the sake of their children^ Their love and affection is a heavenly shelter for their offspring who grow up, protected from the hardships of life. After Allah, the existence of human beings is indebted to the kindness of parents. Therefore, Allah has exhorted us to discharge the rights of parents in the Holy Quran in many places.
The Lord hath decreed that ye worship none but Him and that ye be kind to parents. Whether one or both of them attain old age in their life, say not to them a word of contempt, nor repel them, but address them in terms of honour. And, out of kindness lower to them the wing of humility, and say: My Lord! Bestow on them thy Mercy even as they cherished me in childhood!
Hazrat Muhammad(SAW)has declared that a person who is disobedient to his parents will be deprived of the fragrance of paradise. The Holy Prophet has greatly emphasised that we should serve our old parents because they have spent the energy and capability of their life in the upbringing of their children. It is, therefore, obligatory for the offspring to support the parents in old age. Once the Holy Prophet declared he is degraded! "he is degraded", "he is degraded." The companions of the Holy Prophet asked about this person.
The Holy Prophet explained,
" He is the person who failed to win paradise because he did not serve his parents in old age."
CARETAKER OF THE ORPHANS
Hazrat Muhammad(SAW) was an embodiment of mercy for the orphans and the poor. Before him, there was nobody to look after the orphans and widows. The Holy Prophet (PBUH) raised his fingers and declared the importance of the look after orphans.
The person who looks after the orphans will be in my company in paradis^
RIGHTS OF THE OFFSPRING
Children are the gift of Allah that ought to be treated with kindness, love and affection regardless of their religion, tribe or colour. Parents play a great role in the upbringing of their children. They should take care of all their physical, spiritual and emotional needs.
Before the advent of the Holy Prophet (PBUH) there was an age when people killed their offspring Islam revived the love and affection of man for his offspring. The practice of murder of offspring was eliminated and the love of the parents for their children was restored. In the Holy Quran the murder of the offspring has been prohibited in the following words:
Kill not your children for fear of want; We shall provide sustenance for them as well as for you. Verily the killing of them is a great sin.
RIGHTS OF RELATIVES
After the rights of parents, offspring and wives Islam emphasises the rights of relatives. In social life, a man mostly deals with his relatives after the members of his family. If members of a family discharge their mutual rights properly a happy atmosphere of love and affection will prevail. Otherwise, hatred and estrangement will poison the atmosphere. The peace and harmony of the family will be destroyed. In the Holy Quran as well as in the Ahadees decent treatment with relatives has been repeatedly emphasised Allah says in the Holy Quran:
And render to the kindred their due rights.
The Holy Prophet (PBUH) has declared.
One who breaks himself off his relatives shall not enter paradise.
The Muslims have been ordered to look after the needs of their relatives so that they may not be forced to beg from others. The Muslims have been called upon to give priority to their relatives while spending on account of charity. They should not make their relatives suffer from a sense of loneliness or a sense of inferiority. They should share the sorrows and joys of their relatives. Assistance through relatives does not injure the self-respect of a person. If a man begs others for help he as well as his family is degraded. If we take care of the rights of our relatives according to the teachings of Allah and the Holy Prophet society will be safe from many evils.
Q.2) What human rights are discussed in the last sermon?
The Rights of Human Beings:
If genuine rights of every individual are granted to all the individuals are granted they can devote their talent and energy for the uplift of society with perfect peace of mind. In this way, homogeneous social environment is a feeling of discontent and unrest arises which damages the social orders and destructive tendency paralyzes the constructive capability of the members of the society.
The Rights of Servants:
Allah has enjoyed equal rights to all his beings and no one is superior on the basis of his wealth, color, or caste. Similarly, the servants are to be treated with kindness and love, keeping in mind that they are also the creation of Allah as we are.
The Rights of the Neighbour:
Neighbours enjoy certain rights in our lives which we are obliged to fulfill. By living near each other's house, it is our responsibility to share their sorrows and happiness.
The Rights of the Parents:
In a society, a person gets maximum help and assistance from his parents. Parents are not only responsible for bringing a person in this world but they are not responsible for his upbringing and education. Only parents sacrifice their comforts and belongings for the sake of their children.
Islamiat 9 class Notes Chapter 4 Bodily purification
9th class islamiat surah al ahzab notes Ayat 1 to 73


text:
title: Delete a Git Branch Both Locally and Remotely
---
// locally ((if you know what you are doing!)
    git branch -d localBranchName

    // and then if you need to...
    // on remote
    git push origin :remoteBranchName

## When to Delete branches?

Normally in a contribution flow `Branches` are a great way to work on different features, fixes, etc. while isolating them from the main codebase. So a repo may have a `master` branch, and separate branches to work on different features.

Typically once the work is completed on a feature and it is recommended to delete the branch.

## The Delete workflow:

Lets say you have a repo called as `AwesomeRepo`, and its hosted on Github, at a location such as `https://github.com/my_username/AwesomeRepo`.

Also lets assume it has the branches like:
`master`
`feature/some-cool-new-stuff`
`fix/authentication`
`staging`

For consistency we will assume branch names are same on `local` as well as on the `remote`.

Now, lets say you are done with that fix for authentication and want to remove the branch `fix/authentication`.

## Deleting the branch REMOTELY:

Simply do:

`git push --delete <remote> <branch>`.

For example: `git branch --delete origin fix/authentication`

If you get the error

    error: unable to push to unqualified destination: remoteBranchName The destination refspec neither matches an existing ref on the remote nor begins with refs/, and we are unable to guess a prefix based on the source ref. error: failed to push some refs to 'git@repository_name'

Perhaps someone else has already deleted the branch. Try to synchronize your branch list using

    git fetch -p

The git manual says -p, --prune After fetching, remove any remote-tracking branches which no longer exist on the remote.

## Deleting the branch LOCALLY:

First checkout to a branch other that the one you want to delete:

`git checkout <branch>`.

For example: `git checkout master`

Git will not let you delete the branch you are currently on.

Then proceed with deleting:

`git branch -D <branch>`.

For example: `git branch -D fix/authentication`

redpajama_set_name: RedPajamaGithub


See Army Regulation 420-41 Acquisition and Sale of Utilities Services.
In accordance with Army Regulation 420-41, the Chief of Engineers is the Department of the Army power procurement officer and is responsible for the administration of the purchase and sale of utility services and for policies, engineering, rates, and legal sufficiency in connection with all utility services transactions and contracts in which the Army has a monetary interest. The Chief of Engineers may enter into definite term utility contracts for utility services for periods not to exceed 10 years. The Chief of Engineers may redelegate this authority to the deputy Army power procurement officer.


text:
Black Listed News Race & Culture
Why You Shouldn't Put a Price on Black Babies
Black Listed News Social Justice & Activism
Ruby Bridges and Desegregation
Black Listed Entertainment Music
Prince Launches European Piano Tour
Black Listed Celebrities Entertainment
Woman Charged With Caring for Bobbi Kristina Was Impostor, Police Say
Bad Brains Guitarist on Life Support
Black Listed News What's Happening Now
Students Call Attention to Racism on Social Media
Black Listed Lifestyle Society
Trayvon Martin's Mom Gets Candid
Clinton to Meet With Members of Black Lives Matter Movement
Breaking News: 10 Things to Know on October 8, 2015
Why You Shouldn't Put a Price on Black Babies
Every year, I teach writer Elna Baker's essay, "Babies Buying Babies" to my freshman composition classes as an introduction to narrative and critical thinking. We listen to her This American Life recording and I watch the students cringe, chuckle, and scoff as she recounts her former job at FAO Schwartz, where white Upper East Side moms refused to buy certain dolls because of their skin color. In the end, as non-Black minority dolls gradually begin to be "adopted," Baker admits, "What were left were incubator upon incubator of Black baby dolls." Class discussion is predictable. "It's [insert year here]! I can't believe we haven't gotten past this!" Obama is often evoked as an arbiter of how much less racist these 18-year-olds think the country is now than it was "back in the day."
Usually my goal, to remind students of the insidious ways in which racial prejudice impacts even the most innocuous of activities, is achieved. But last year, a Black student raised her hand. "I don't see that much wrong with this," she shrugged. "My mom only bought me dolls that looked like me, too." As other students nodded, I thought to myself, it's time to reassess this lesson. For that class, the takeaway wasn't that White moms didn't want to "adopt" Black dolls. It was that more Black families should. That sentiment can be applied to the topic of real-life adoptions. There is merit in matching Black babies with parents who look like them – particularly if a greater number of those babies are left languishing in the adoption and foster care systems, and especially when those babies are discussed like salable commodities.
NPR recently launched The Race Card Project, an initiative that invites participants to submit six-word sentences related to race. Morning Edition dissected one such sentence last week in a piece titled "Six Words: Black Babies Cost Less to Adopt."
In this article:adoption, black babies, slavery, white babies
EBONY Enjoys Ghana's Art, Music, Food and Culture Scene
Slave Food: The Impact of Unhealthy Eating Habits on the Black Community
YG Portrays Slavery & Lynching in New Video, 'Stop Snitchin'
Ancestry.com Apologizes for Ad Depicting Slavery-Era Interracial Romance

redpajama_set_name: RedPajamaCommonCrawl


text:
Erhard Busek Ph.D., Special Coordinator of the Stability Pact for Southeast Europe
The EU's Future Can Be Settled Through Shared Efforts
Austria faces a stark choice for its head of state: Green Party professor Alexander Van der Bellen or Norbert Hofer of the far-right Freedom Party, who won a decisive victory in April's first round of voting
"The current presidential elections in Austria are a completely new move. The candidates traditionally come from the two governmental parties, but this time their representatives did not succeed in the first round of the election. The background to this rift between candidates Van der Bellen and Norbert Hofer is the current political situation with the up and coming "Freedom Party of Austria", which is without a doubt a right wing party. This is why their candidate, Norbert Hofer, is trying to appear like a softy. Nobody knows what position he might have after the elections," says Erhard Busek in an exclusive interview for this special CorD "Partners" edition covering the Austrian-Serbian bilateral relationship.
Could Hoffer's possible victory lead to a change in the course of Austrian foreign policy?
For the moment, Hofer does not favour Austria's exit from the European Union, but nobody knows what will really happen if he is elected. Migrants and tolerance is a general debate in Austria, and Hofer is not alone in being critical with regard to migrants and also limited tolerance.
Considering the large number of Austrian voters with Serbian origins, who do you think will be their favourite in the election?
The majority of Austrian Citizens with Serbian origins are traditionally in favour of "The Freedom Party of Austria". The head of "The Freedom Party of Austria", Strache, was always against the independence of Kosovo and therefore he was also campaigning for Serbian votes in a very direct way. It is also interesting that this party shows some sympathy for Vladimir Putin.
Have you changed your stance – expressed back in the year 2000 – that Kosovo should be independent?
I did not change my mind.
How do you see Serbia's EU accession process?
The prospects of Serbia joining the European Union are really positive. I think it is really moving forward, because the government in Belgrade is doing a lot to move the country closer to the European Union.
How would you assess current regional relations in the Western Balkans?
Regional Cooperation in general has to grow in Southeast Europe. Not all opportunities are being used to achieve better results in the region by creating more cooperation. For example, in infrastructure and in the economy, and in cooperation that doesn't relate only to the migrant issue. The friction you are asking about is not very helpful, but it is always a responsibility of both parties.
Youare coordinator of the Southeast Cooperative Initiative (SECI), which was initiated by the U.S. as a means of supporting the Dayton Peace Accords. Twenty years after its signing, how would you evaluate the functioning of this agreement?
I was always very critical of the Dayton agreement, because the arrangements concerning the statute of Bosnia-Herzegovina are not sustainable. The differences between Republika Srpska and the Federation are obvious. The international community is always waiting for a move within B-H itself, but obviously there is nothing really happening. The move in Republika Srpska towards an independence referendum was not really helpful.
Many consider that Serbia's EU accession prospects are rather vague, while the Western Balkan region is no longer in the EU's focus. What is your assessment of this issue?
For the moment, the European Union has a lot of internal problems that make it more difficult to determine a timeframe for the European perspective, but Brussels is still interested, as are some member states in particular, like Germany and Austria. This is shown by the Berlin Process, which created some forward momentum in the last two years.
From the Austrian perspective, how do you see the future of the EU? Are you concerned when German Foreign Minister Steinmeier says that there is a fear that the EU could meet its end?
At present there are a lot of opinions regarding the future of the European Union. I think it would be better to sit together and create more things in common, because the problems are also common and nobody is able to solve them individually. It should be considered that Europe represents only seven per cent of the world's population but that it still accounts for more than 20 per cent of the world's economy. Out of this we have to do a lot!
Do you believe that the migrant crisis has been brought under control, and what does the inability to reach a consensus regarding steps to combat it say about the EU?
The migrant crisis is still not resolved. We have learned a lot, but border control, for example, has not yet really been ensured. This has to be done jointly, because of the question of how to control the borders of Greece, with such a great number of islands?
How would you rate general bilateral relations between Austria and Serbia?
In general, relations between Serbia and Austria are quite good. Current foreign minister Sebastian Kurz always expresses some friendly statements, but it really depends on what we do for different countries. In the case of Serbia, Austrian foreign policy and the business community are still very much engaged.
For the moment, the European Union has a lot of internal problems that make it more difficult to determine a timeframe for the European perspective, but Brussels is still interested, as are some member states in particular, like Germany and Austria
Alongside very good economic cooperation, Austria has also engaged in helping Serbia with the reform of education, by proposing the model of dual education. Given that you personally participated in the reform of the education system, what do you think of that model?
The system of the dual education model is really important. It represents one of the possibilities for the economy to move forward, but it is not an isolated field. It also has to be implemented in both school and university education. We are trying to contribute, for example, via the Centre of Advanced Studies, now based in Rijeka, which promotes cooperation for the region and is proceeding quite well. The dual education model is not in favour of a cheap labour force, but rather higher quality among educated people, which enables them to compete as business heavyweights!
You made an appearance earlier this year as a lecturer at the Faculty for Media and Communications (FMK), where you spoke about the media as a prerequisite for greater democracy. How would you rate the media scene in the region?
The situation of the media – not only in the region, but in general – is for the moment really horrible, but a free media is a precondition for more democracy and, as such, we have a lot to do in this direction. I am very much engaged in fighting on this, but the real dangers are in other countries more than in Southeast Europe.
On the other side, media investments from the West are not really a success story in the long run. I think more transparency is generally necessary here, but not only in this region, rather across the whole of Europe.
In the region there is an award bearing your name. It is intended for journalists and media experts who contribute to improving understanding in Europe. Is the role of the individual in today's world undermined or exaggerated?
For the moment, we have tough general discussions on this. The right understanding about the role of media and democracy is lacking. So far, I am supporting this with the Media Award, but also with a lot of training activities and public discussions.
Austria 2016
Erhard Busek
Ambassador Lutterotti hosts Austrian Business Circle Summer Reception
Austrian Business Circle Summer Reception
Cabaret with Lisa Eckhart
Austria – Partners 2016
Special editions 19th November 2016
Austria 5th December 2016
H.E. Johannes Eigner, Ambassador Of Austria EU
Perhaps Not in Focus, But Certainly Not Forgotten
Austria 1st December 2016
There is admittedly no clear answer regarding precisely when and how the goal of full EU membership will be achieved – but it is certain that convincing reform programmes in the individual candidate countries will greatly help to bring more clarity
Erika Teoman-Brenner, Commercial Counsellor at the Embassy of Austria in Belgrade
Reforms Are Paying Off
Interviews 1st December 2016
The Serbian Government's firm commitment to follow the EU path definitely reinforces the trust and confidence of the Austrian business community in Serbia. The 2nd AUSTRIA CONNECT conference 2017 - the largest gathering of Austrian companies active in the Balkan markets - will take place in Belgrade and provide new business opportunities
Special editions 31st October 2015
Significant Grofth of Cooperation and Friendship


text:
Atticus Essay III (Massachusetts)
Dubber Amundson
Observations On the letter of the Hon. E.G. Esq; published in the Independent Chronicle, Nov. 8, 1787, and other pieces lately published in opposition to the Federal Constitution: In LETTER III.
From a Gentleman in the country, to his friend in town.
"Who shall decide when Doctors disagree,–
And soundest Casuists doubt."
I Must postpone my designed answer to the question, with which I concluded my last letter, (whether there be any power, or principle, in our Commonwealth, sufficient to keep within proper bounds, the contests of the great and little men amongst us?) and must now attend to your favour of November 14th.
You have read the letter of the Hon. E[lbridge] G[erry] and it seems to have given you some disturbance. The letter I have several times perused, with great attention; yet find not, that it contains any thing which ought greatly to offend us. It seems to be an excuse for his d[issent] from the federal system. Ought we to resent his apology with anger? We too, must think for ourselves. The only question here, seems to be, Whether, after the business of the delegation was finished, a delegate, any more than any private gentleman, could with propriety, write to the Legislature, either for or against the adopted system? Especially as a State Convention, and not the Legislature, were to decide the important question.
His observation, "that the greatest men may err," is of real importance, and leads to this conclusion, that the Hon. E[lbridge] G[erry] may err. If the authority of a Washington, a Franklin, or a Rufus King, supported by the authority of all the Statesin a Convention, be no good argument in favour of their system; then, by parity of reason, the authority of the Hon. E[lbridge] G[erry] or a Randolph, or a Mason, can be no better argument against it. Between these great Casuists, the people, in Convention assembled, must judge; and to this decision, we hope, they will bring cool heads and pure hearts.
The federal system determines, that every branch of its Legislature shall be elective; the qualifications of electors are ascertained; and caution is taken that elections be not held at an inconvenient place. The time, whether in July, May or August, or other month of the year; the manner, whether by ballot or otherwise, is to be regulated by state, or federal laws. Here I can see no great "insecurity of the right of elections." Nor do I fear, that the federal government will not be as likely as the State Legislatures, to fix on some method, by which the sense of the people shall be fairly taken. As to the representation, it seems to be as large, as the state of our country will well admit of; and as well defined, as numbers can make it. If those observations be just, is "the representation inadequate," or "elections insecure?"
Yet the Hon. E[lbridge] G[erry] has reasons on which his objections are founded, to be divulged when he shall return to Massachusetts. If reasons he hath, by all means let us hear them; and let us confront them by better reasons, if we can.
The Hon. E[lbridge] G[erry] and others, complain, that the system has not the security of a bill of rights. That series of propositions commonly called a bill of rights, is taken out of lawbooks, and is only an extract of the rights of persons.–Now let us suppose, that it stands in a law-book, which is appealed to, as an authority, in all the Courts of judicature, or is tacked (without pains or penalty annexed to the violation of it) as a preface to the Constitution. In which case is it likely to afford the greatest security to the rights of persons? Let the unbiased judge. On this point we may appeal to fact. There is a Commonwealth, with which we are not wholly unconnected, which hath a bill of rights prefixed to its Constitution. Yet ask those of either of the great parties, into which that State hath lately been divided, if this bill of rights hath not been frequently violated? If you confide in the zealots of each party, will you not be ready to conceive, that the actual Legislators have had as poor an opinion of the bill of rights, as Cromwell had of Magna Charta? If you speak to the moderate men in that same State, they will perhaps shrug their shoulders, and shake their heads, and give you no answer.
When the powers to be exercised, under a certain system, are in themselves consistent with the people's liberties, are legally defined, guarded and ascertained, and ample provision made for bringing to condign punishment all such as shall overstep the limitations of law,–it is hard to conceive of a greater security for the rights of the people.
It hath been said, that the Constitution proposed, "has few federal features, but is rather a system of national government." Perhaps the features of a confederacy, and of a national government, are happily blended; as a child may have a resemblance of both its parents. If so, may not the event be happy for us? For is it not for want of national government, that commerce, husbandry, mechanics, the arts and manufactures, are no languishing and seem ready to die? was it not for want of this, that the States of Greece, were enslaved by a petty monarchy, that Switzerland is destitute of national importance, and Holland torn with all the distresses of a civil war? Must not the States of America, without this, serve with the fruits of their hardy industry, their enemies in Britain. Dean Tucker (whose political prophecies have mostly been verified) hath predicted concerning America, "that they will be a contemptible people to the end of time." Without national government, must it not be so in fact? for a confederacy, without energy sufficient to bring the confederates to joint-action, is a mere nullity. Let us not quarrel about words and sounds, national or federal; it is a good system if its tendency be to make us a happy people.
It is said that it "dissolves the state governments, because it makes the federal laws supreme in each State." What bond of union could there be without this? It ought to be allowed, however, that the powers given to Congress in this system, are the utmost extent of the federal legislation. If these relate to matters of merely national concern, they do not interfere, any more than they ought, with the legislative powers of particular States.
It is suggested that this system may be "amended" before its adoption. On this two questions arise; when are the people groaning under present burthens, to be eased of the expences of conventions and assemblies, for settling government? and will there probably be fewer dissentients from the amendments, than from the system as it now stands?
Should it be received as it now stands, it is suggested "that our liberties may be lost." The caution expressed in the word may, is commendable, because many persons whose abilities the modesty of the Hon. E[ldridge] G[erry] would not suffer him to undervalue, think quite otherwise. Too, too long it hath been the humour of our countrymen, to be so fearful of giving their rulers power to do hurt, that they never have given them power to do good. This is the very reason why the public authority, hath been so much despised by the people; and why the people have so little attachment to their civil institutions.
When such a great affair is depending, parties, disputes, and objections, are to be expected. It is best I believe that they should, in a certain degree, take place. I hope they will not proceed to violent extremes. The State of Massachusetts is not bound to imitate Pennsylvania: Let not our good citizens make passion for counsil; but let them choose men of clear heads, and honest minds, for their State Convention. When the "greatest of men" differ, the assembled people must decide. And let them, after the affair is impartially examined, and thoroughly sifted, received, amend, or utterly reject the Federal Constitution. Let not the leading characters among us, in the mean time, forget that excellent advice of the Hon. E[ldridge] G[erry] worthy to be written for their use in letters of gold, that they preserve moderation.
Further communications and correspondence on those interesting subjects, will be agreeable to your friend ATTICUS.
A Democratic Federalist (Pennsylvania)
Tobias Lear to John Langdon, Mount Vernon (Virginia)
Federalist Paper No. 79 (New York)


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Frontiers in Bioengineering
and Biotechnology
Bionics and Biomimetics
Bionic Soft Electronics View all 7 Articles
ILKWON OH
Korea Advanced Institute of Science and Technology, South Korea
Jinhan Jeon
Bosch (Singapore), Singapore
Luigi Manfredi
School of Medicine, University of Dundee, United Kingdom
PNP Soft Gripper
Conclusion and Future Work
Front. Bioeng. Biotechnol., 19 May 2020 | https://doi.org/10.3389/fbioe.2020.00472
A Novel Soft Bending Actuator Using Combined Positive and Negative Pressures
Mohammad Fatahillah, Namsoo Oh and Hugo Rodrigue*
Soft Robotics Laboratory, School of Mechanical Engineering, Sungkyunkwan University, Suwon, South Korea
Most soft pneumatic actuators for producing bending actuation have made use of either positive or negative pressure and adjusted their design in consequence. In the proposed paper, a novel soft bending actuator using combined positive and negative pressures (PNP) where the bending force of a negative pressure actuator and a positive pressure actuator is combined into a single actuating structure. This actuator is capable of producing a blocked force as high as 150 N at a combined positive pressure of 60 kPa and negative pressure of 60 kPa while still being able to produce large bending deformations. It was found that the equilibrium angle of PNP actuation is lower than using only negative pressure but that the actuator can produce larger forces at angles below the equilibrium angle of using positive pressure only. The actuator can use PNP actuation to produce large forces at lower bending angles and negative pressure actuation for producing large bending angles. This actuator was implemented in a soft robotic gripper capable of lifting large objects weighing up to 4 kg and a soft pinching gripper capable of holding a notebook weighing 1.85 kg by pinching it. The proposed actuator is capable of large forces and is versatile such that it is expected to be used in applications such as agriculture where many objects tend to be large and heavy yet require a delicate touch.
Soft robotic grippers have attracted significant attention from industry for grasping objects in unstructured environments due to their compliance and ability to grasp objects without requiring precise alignment. Particularly, soft pneumatic grippers have shown significant promise as they can conform themselves to the surface of the object and because the force produced by these actuators can easily be modulated through varying the applied pressure (Rus and Tolley, 2015; Mirvakili and Hunter, 2018; Shintake et al., 2018). However, the grasping capabilities of soft pneumatic grippers is limited by the bending force of the soft pneumatic actuators from which their fingers are made.
Fluidic elastomer actuators (FEAs) generally consist of a polymeric matrix with cavities that expand upon pressurization and whose expansion causes an asymmetric deformation of the actuator which results in a bending motion. This is generally done by having a strain differential across the thickness of the actuator causing the longitudinal expansion of the actuator to produce a bending deformation. This anisotropic expansion can be induced into single material actuators by using walls of different thicknesses or by using asymmetric wall shapes (Wakimoto et al., 2009; Gorissen et al., 2011). The addition of a strain-limiting layer on one side allows for better bending actuation performance through a larger strain differential (Ilievski et al., 2011). Adding a second constraint in the radial direction allows to focus the inflation in the longitudinal direction through the walls of the actuator not overinflating when pressurized. This radial constrain has generally been achieved through thicker wall thickness in the radial direction or by using fiber reinforcements either wrapped around the actuator or embedded within the matrix itself (Suzumori et al., 2007; Deimel and Brock, 2013; Galloway et al., 2013; Mosadegh et al., 2013; Polygerinos et al., 2013; Connolly et al., 2015). Using multiple cavities can also be used to realize bending in multiple directions (Suzumori et al., 1991; Martinez et al., 2013). These designs can also be realized through 3D printed polymers which allows for easier scaling down of the resolution or more complex designs (Schaffner et al., 2018; Vogt et al., 2018; Zhang et al., 2019). 3D printed thermoplastics have also been used to produce bending actuators capable of bending forces up to 80 N at a pressure of 200 kPa, the largest bending force of all of the surveyed pneumatic bending soft actuators (Yap et al., 2016).
The use of thin films or textiles instead of rubbers permits the fabrication of very lightweight actuators without necessarily lowering their performance in comparison with polymer-based actuators. Pouch motors with rigid constraints between pouches have been used to produce bending actuators (Niiyama et al., 2015; Oh et al., 2019). Tubes made with inextensible materials with folds have been used to realize smooth or jointed deformations using thermoplastic films (Nishioka et al., 2012, 2017; Amase et al., 2015; Sareen et al., 2017). Bending actuators using inflatable bellows and folded tubes have been developed capable of large forces and deformations (Best et al., 2015; Felt, 2019). The use of anisotropic textiles has been used to make bending actuators for wearable applications (Cappello et al., 2018).
Although all of the aforementioned actuators rely on a positive pressure differential with the environment, it is also possible to produce movement through a negative pressure differential with the environment (Yang et al., 2015, 2016, 2017; Robertson and Paik, 2017; Jiao et al., 2019; Lee and Rodrigue, 2019). Bending vacuum-based actuators have been realized using a rigid skeleton placed inside of a bladder (Li et al., 2017). Similar vacuum-based bending actuators have been realized used 3D printed structures with a measured maximum blocked force of 16 N (Tawk et al., 2018). However, all fluidic-based soft bending actuators have either used either positive or negative pressure.
The present work shows how both positive and negative pressures (PNP) can be used in tandem to produce greater bending forces and some of the limitations of doing so. A soft bending actuator combining PNP chambers into a single actuating structure where the force of both actuators is combined to produce large bending forces is presented in this paper. The effect of this design on both the bending angle and force of the actuator is demonstrated experimentally and compared with a simple quasi-static model. The design, manufacturing, and experimental results of the actuator are presented, and the performance of the actuator applied to a gripper for gripping large and heavy objects is presented. Notably, the actuator produced a maximum blocked bending force of 150 N, which is larger than any of the surveyed pneumatic soft bending actuators.
Actuator Design
The proposed PNP actuator consists of a single structure containing two separate pneumatic actuators where the pressurization of one and/or the vacuuming of the other causes the actuator to bend. The simultaneous pressurization and vacuuming of the respective actuators cause the structure to produce a larger bending force over a certain bending range than simply actuating either. As this actuator contains two different actuators, its actuation properties will depend on the characteristics of the actuators used and their respective actuation pressures.
The negative pressure actuator used in this work is composed of a sealed textile chamber containing a semi-rigid plate onto which rigid walls are attached. Vacuuming of the chamber causes the textile to push around the rigid walls and the semi-rigid plate to bend (Figure 1A). Although there are differences in geometry and materials, the base actuation mechanism is the same as previous works on vacuum-based bending actuators (Li et al., 2017; Tawk et al., 2018). The positive pressure actuator is a pouch motor located between the free ends of the rigid walls of the negative sub-actuator and its inflation causes a contractile force that pulls the free-end of the rigid walls toward each other that results in a bending motion of the semi-rigid plate in the same direction as that of the vacuuming of the negative pressure sub-actuator (Figure 1B). The pouch motor is similar to existing works in terms of function and materials, but its implementation into a bending actuator with a strain limiting layer differs from previous designs. The main differentiation with previous works is the use of both types of actuators in a single actuating structure. Simultaneous actuation of both positive and negative pressure chambers thus causes both actuators to create a bending force of the overall structure (Figure 1C).
Figure 1. (A) Bending deformation of the actuator with only negative pressure actuation, (B) linear motion of a pouch motor, and (C) bending deformation of the actuator combining PNP actuation. Equilibrium of the actuator using (D) negative pressure actuation only and (E) PNP actuation.
It is to be noted that both actuators will likely have different equilibrium angles and that bending further than their respective equilibrium angle will cause this actuator to output a negative bending force. The negative bending force produced by either actuator will reduce the total bending force of the actuator as well as its maximum bending angle vs. using only the actuator with the highest bending angle. This can be seen in the proposed actuator by comparing the maximum bending angle using only negative pressure actuation and using PNP actuation (Figures 1D,E). The advantage of the proposed concept is the increased bending force produced at bending angles smaller than the equilibrium angle of the positive pressure actuator. However, it is still possible to use only negative pressure actuation for reaching large bending angle.
In the actuators presented in this work, the semi-rigid plate serving as the base of the actuator is manufactured from a 3 mm thick polycarbonate (PC) sheet which is cut into a rectangular shape using a laser cutter. The rigid walls are 3D printed using polylactic acid (PLA) filament and glued onto the PC sheet using superglue (Loctite 401, Henkel) (Figure 2A).
Figure 2. (A) Assembly process of the actuator, (B) dimensions of the actuator used for modeling, and (C) testing jig for measuring the bending force at different bending angles.
The sealed chambers of the actuator are made from a technical textile consisting of a one-sided thermoplastic polyurethane (TPU)-coated nylon fabric. Three sheets of textile are used in total where two are used for the upper and lower surfaces of the actuator and the third is for forming the pouch motors by bonding it to the inside portion of the upper textile sheet using an impulse sealer. The upper and lower surfaces are then bonded to form the negative chamber into which the plate and walls assembly is inserted.
The principle of conservation of energy will be used to produce a quasi-static model of the proposed PNP actuator. It is assumed that the film does not store any elastic energy and that the semi-rigid plate does not require any force to deform. This can be expressed as follows.
dWin = dWout (1)
Where the input work Win is the work of fluid added or removed from the actuator and Wout of the output mechanical work of the actuator. The work of the fluid can be divided into the work of the negative and positive pressure actuators as follows.
PNdVN+ PPdVP = Mdϕ=Fldϕ (2)
Where PN and PP are, respectively, the pressures of the negative and positive pressure actuators, VN and VP are, respectively, the volumes of the negative and positive pressure actuators, M is the moment produced by the actuator and ϕ is the bending angle of the actuator (Figure 2B). This moment can be converted into the bending force F based on the moment arm l of the actuator, which is equal to the length L0 of the actuator when the force is applied at its tip. All pressures are gauge pressures. Assuming that the base of the actuator deforms with a constant radius of curvature throughout the motion we can obtain the following equations for the negative pressure sub-actuator.
L0=2θ1(r1+h) (3)
r1sinθ1=L2 (4)
Where L0 is the length of the semi-rigid plate forming the base of the actuator, r1 is the radius of the curve of the negative pressure sub-actuator, θ1 is the central angle of the negative pressure actuator also equal to half of ϕ, h is the height of the rigid walls of the actuator and L is the current length between the free-ends of the rigid walls. We can then obtain the following equations for the positive pressure sub-actuator.
L0=2θ2r2 (5)
Where r2 is the radius of the curve of the positive pressure actuator and θ2 its central angle. The relation between θ1 and θ2 can then be obtained from equations (4) and (6) as follows.
2sinθ1(12θ1-hL0)= sinθ2θ2 (7)
This equation can be solved numerically or by using an approximation such as the Taylor series expansion. The area Ap of the positive pressure sub-actuator can be approximated as an airfoil shape with cylindrical surfaces as done in previous works on pouch motors.
AP = L022(θ2-cos θ2 sin θ2θ22) (8)
The area An of the negative pressure sub-actuator can be approximated as the sector formed by the line of the rigid walls minus half of the airfoil shape of the positive pressure sub-actuator and minus the triangular formed by the center of the circle of the sector and the free-ends of the rigid walls.
AN = L024θ1-[(L02θ1-h)2(sin2θ12)]-[L02(2θ2-sin2θ2)8θ22 ] (9)
The volumes can then be obtained by multiplying equations (8) and (9) by the depth D of the actuator as follows.
VP=L02D2(θ2-cos θ2 sin θ2θ22) (10)
VN=L02D4θ1- [(L02θ1-h)2(sin2θ12)]D -[L02(2θ2-sin2θ2)8θ22]D (11)
These two equations together with equation (7) can then be differentiated and inserted into equation (2), but this results in a long formula that is omitted for brevity. As was done in this paper, it is also possible to use simple numerical methods such as finite difference approximation to evaluate these derivatives and evaluate the bending force produced by the actuator as a function of the bending angle.
Some simplifications of the geometry were made in terms of the chambers having a constant cross-sectional area throughout its width, which would not hold true toward the edges of the actuator for either of the chambers. The model predicts that the bending force produced toward zero bending angle is infinity for negative pressures. This is not feasible in practice as it assumes ideal unstretchable materials and that absolutely no manufacturing errors were made. Even a slack of 1–2 mm in the film would significantly affect the force at zero bending angle. It would be possible to develop a dynamic model of the actuator to predict its speed and frequency response, but this model would have to consider the dynamics of the pneumatic systems including its pump, regulators and valves as well as any drag forces induced by the pneumatic tubing.
A testing jig was manufactured to measure the bending force produced by the actuator at different bending angles (Figure 2C), and the bending force was measured using a load cell (CB1-K50, DaCell). The pressures within the positive and negative chambers were controlled using an electro-pneumatic regulator (ITV-1030, SMC) and an electronic vacuum regulator (ITV-2090, SMC), respectively. All experiments with error bars were repeated three times with the same actuator.
An actuator with a single actuator chamber with dimensions of 30 mm in length, 80 mm in width and 30 mm in height was built and installed on the testing jig and connected to the electro-pneumatic regulators. Its bending force produced using either only negative or positive pressure was measured for pressures ranging from 20 to 60 kPa in increments of 20 kPa. The bending force produced by the actuator using only negative pressure at low angles does not reach infinity due to stretchability of the material and manufacturing errors, but the bending force produced by the actuator follows well the predicted trend throughout most of the range of angles (Figure 3A). The bending force produced by the actuator using only positive pressure exceeds that predicted by the model, but the equilibrium angle of the model and the experimental results are in general agreement (Figure 3B). The difference in bending force could be due to the assumption made that the cross-section of the actuator is constant throughout and due to manufacturing errors. The bending force using both negative and positive pressure for equal pressures from 20 to 60 kPa in increments of 20 kPa was then measured (Figure 3C). This experiment was conducted such that when the positive pressure actuator has a positive pressure of 20 kPa then the negative pressure actuator has a negative pressure of 20 kPa. The actuator follows well the predicted trend and appears to behave as the sum of the bending forces of the negative and positive pressure-only bending forces as predicted by the model.
Figure 3. Bending force vs. bending angle at different pressures for (A) negative pressure actuation, (B) positive pressure actuation, and (C) PNP actuation. Equilibrium angle of the actuator with a single segment using (D) negative pressure actuation, and (E) PNP actuation. (F) Blocked force of the actuator vs. pressure.
An important value that can be observed to be predicted accurately by the model is the transition angle from PNP actuation producing a higher bending force to negative pressure-only actuation producing a higher bending force. This angle can be measured at the angle where negative pressure and PNP actuation produce an equal bending force. This value is important as it becomes preferable to use negative pressure actuation over PNP actuation at bending angles exceeding it. This value was measured to be equal to ~10° based on the values obtained experimentally for negative pressure and PNP actuation at all three tested pressure (Figures 3A,C) while the predicted value was 10.22° according to the numerical model. This value is for an actuator with a single segment, but an actuator with multiple segments would have a multiple of this value for the transition angle.
Next, the equilibrium angle of the actuator was measured for negative pressure and PNP actuation. This angle corresponds to the bending angle reached by the actuator at zero blocking force. This equilibrium angle was measured visually by using a pressure of 40 kPa for negative pressure actuation and with pressures of 40 kPa for both the positive and negative pressures using PNP actuation (Figures 3D,E). The measured equilibrium angles were 45.0° when using negative pressure actuation and 34.7° when using PNP actuation. This means that below 10° PNP is preferable, between 10 and 34.7° negative pressure is preferable and that between 34.7 and 45° only negative pressure is able to produce a bending force.
The blocked force of the actuator for positive, negative and PNP actuation was tested in the horizontal position up to 60 kPa (Figure 3F). It can be seen that the maximum force produced using only negative pressure was measured to be 113 N, using only positive pressure to be 29 N and using PNP to be 150 N. The force produced in all three modes was proportional to the input pressures, and the force achieved by PNP actuation is equivalent to that using only negative pressure plus using only positive pressure. With this configuration the use of PNP actuation produced an increase in blocked force of ~35%, which is substantial. The maximum blocked force achieved by the actuator is nearly double that of the highest blocked force produced by the surveyed pneumatic soft bending actuators. It is also to be noted that it takes longer for the actuator to reach a negative pressure of 60 kPa than it does to reach a positive pressure of 60 kPa due both to the larger volume of the vacuum portion of the actuator and the characteristics of pneumatic pumps.
Although soft grippers are quite adept at gently grasping small items that fit into the palm of a hand, few soft grippers have focused on grasping large objects whose weight may range up to a few kilos. This category of objects represents a sizeable portion of the objects found around us. A large gripper with four antagonistic fingers placed antagonistically with a total width of 270 mm was built using four PNP actuators with five segments and a total length of 144 mm each, a width of 50 mm and a height of 30 mm.
It was seen previously that PNP actuation produces larger bending forces at lower bending angles while using only negative pressure for actuation results in a larger maximum bending angle. Considering this, it can be expected that PNP actuation would be preferable for grasping larger objects where a smaller bending angle is required to make contact with the object whereas using only negative pressure for actuation would be preferable for smaller objects where a larger bending angle is required for actuation. The maximum payload of the gripper for either negative or PNP actuation was tested for cylindrical jigs where the weight of the jig can be adjusted. Cylindrical jigs with external diameters of 60, 115 and 165 mm were tested with a negative pressure of 20 kPa for both cases and a positive pressure of 60 kPa for PNP actuation (Figures 4A,B). These values of the pressure were chosen as they are the pressures achieved by the actuator after ~1 s of actuation using a portable pump due to the negative pressure chamber being larger than the positive pressure chamber and due to the flow of air being larger for positive pressure. Results show that the gripper is capable of lifting much larger loads when using PNP for larger objects but that it is preferable to use negative pressure actuation for smaller objects (Figure 4C). Either type of actuation is suitable for medium-sized objects.
Figure 4. (A) Testing jig for maximum load vs. pipe diameter experiment (165 mm diameter pipe pictured), (B) gripper grapping the jig using PNP actuation, and (C) results for the maximum load for different pipe diameters. The gripper using PNP actuation for grasping (D) a head of cabbage (2.20 kg), (E) a large jar of cheese puffs (0.55 kg), (F) a large-sized box of cereals (1.30 kg), (G) a bag of rice (4.00 kg), (H) a head of cabbage (2.00 kg), and (I) a bag of onions (1.20 kg). The gripper using negative pressure actuation to grab (J) a carton of milk (0.28 kg), (K) a tangerine (0.06 kg), and (L) a boiled egg (0.04 kg).
As the intended application of the proposed gripper is to grab larger and heavier objects found around us, the gripper was given some of the larger and heavier objects that can be found in a grocery store including a head of lettuce, a large jar of cheese puffs, a large-sized box of cereals, a bag of rice, a head of cabbage and a bag of onions (Figures 4D–I, Supplementary Video). The heaviest of these objects weighs 4 kg while others are large, slippery or cannot be grasped from the bottom. Smaller objects such as a carton of milk, a tangerine and a boiled egg were then grasped using only negative pressure by using the fingertips of the gripper (Figures 4J–L).
A second gripper was built for pinching applications when grabbing large and slender objects which cannot be power grasped yet require large normal forces to produce the frictional force required to hold these objects. This soft pinching gripper consists of two antagonistic finger each with a single chamber with a width of 80 mm, a height of 30 mm, a length of 30 mm and a gap between the fingers of 15 mm. With the same pressures as the previous gripper, the equilibrium angle for negative pressure actuation was measured to be 45.0° and 34.7° for PNP actuation. The maximum weight held at these pressures by the gripper on a flat jig with a thickness of 15 mm made from acrylic plates was measured to be 2.0 kg for negative pressure actuation and 3.6 kg for PNP actuation, which represents an increase of 80% in the maximum payload (Figures 5A–C). The gripper was then made to grab flat and wide objects that cannot be grasped using a power grasp such as a notebook, an acrylic plate, an electronic tablet, a book and an envelope (Figures 5D–H). Weighing 1.85 kg, the notebook is the heaviest of these objects and is an object that most soft robotic grippers would struggle to successfully grasp and hold due to its large size and slippery surface.
Figure 5. (A) Jig for testing of soft pinch gripper, (B) soft pinching gripper grasping this jig, and (C) maximum load for the soft pinching gripper using PNP actuation and negative pressure actuation. The soft pinching gripper grasping (D) a notebook (1.85 kg), (E) an acrylic plate (0.40 kg), (F) an electronic tablet (0.66 kg), (G) a book (0.78 kg), and (H) an envelope (0.01 kg).
Most soft pneumatic actuators use positive pressure for actuation and a few recent actuators have used negative pressure for actuation. This is the first actuator where a combination of both simultaneous positive and negative pressure can be used in a single actuator to create a larger bending force. It was seen that both positive and negative pressure actuation can contribute to the force produced by the actuator. The actuator's range of motion can be reduced since the actuator is a combination of two separate structures with different equilibrium angles such that, in the case of the design presented in this work, the positive pressure structure creates a negative bending force above its equilibrium angle. This is specific to the design presented in this work and the use of different dimensions could make both positive and negative pressure structures have equal equilibrium angles. A different design could perhaps make the equilibrium angle for both positive and negative pressures equal regardless of the dimensions of the actuator.
This reduction in the maximum bending angle might an issue when trying to grab objects requiring large deformations of the fingers, but the addition of positive pressure is not necessary to drive the actuator such that positive pressure actuation can be used selectively when trying to grab larger and heavier objects. An increase of 35% in the maximum blocked force was measured for PNP vs. using only negative pressure, but this was measured by using equal values of negative and positive pressures. Negative pressure is limited in pressure due to the limit between a perfect vacuum and room pressure while positive pressure can be increased as high as the structure can withstand. Future version of the actuator may be able to hold much higher pressures than those shown in this work such that the increase in blocked force may be much larger.
When used to grab objects using either power grasping or pinch grasping, the actuator is capable of outputting very large bending forces using PNP actuation at lower bending angles that can be used to grab larger and heavier objects. Negative pressure actuation can be used to grab smaller and lighter objects at higher bending angles. The design can also be used to build pinching grippers that can grab flat and wide objects that might require large blocked forces to produce enough frictional forces to prevent the object from slipping. The range of objects grasped in this work in terms of dimensions, shapes and weight is quite different from previous works focusing on smaller objects that can fit in the palm of a human hand and shows how soft robotic actuators can be also be used for objects that have not traditionally been linked with soft robotics. It is expected that this kind of gripper could be used in agriculture where some vegetables are large and heavy while still requiring a gentle touch to not damage them.
A novel design for a pneumatic soft bending actuator able to actuate using both positive and negative pressure was presented in this work. The main novelty of this work consists of using both positive and negative pressure for soft actuation which was demonstrated to be able to increase significantly the blocked force of the actuator. The maximum blocked force of the actuator measured in the work was ~150 N, which is larger than any of the other surveyed pneumatic soft bending actuators. This blocked force was achieved at the relatively low pressures of 60 kPa of positive pressure and 60 kPa of negative pressure. It was seen that the maximum bending angle of the actuator was reduced when PNP actuation was used, and that the increase in bending force is only for a given range of actuation. Above this point, using only negative pressure results in higher bending forces and larger bending angles. The actuator can be used in both modes of actuation and can thus benefit both from large forces at smaller bending angles and from larger maximum bending angles.
The proposed actuator was used to form two types of soft gripper. The first is a large power grasping gripper for larger objects that are often heavier than smaller ones but that can still grab smaller objects using negative pressure actuation. The second is a pinch grasping gripper meant to grab flat and wide objects requiring large blocked forces to produce sufficient friction force and prevent the object from slipping. Future work will focus on reinforcing the construction of the actuator to increase the maximum positive pressure held by the actuator and on further improvements to the design as well as testing the gripper for agricultural applications.
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation, to any qualified researcher.
MF and NO developed the experimental setups and conducted all experiments. MF and HR developed the numerical model, carried out the data analysis, and wrote the manuscript.
This work was supported by the Technology Innovation Program (10080336) funded by the Ministry of Trade, Industry & Energy (MI, Korea) and by the National Research Foundation of Korea (NRF) grant funded by Ministry of Science, ICT & Future Planning (No. 2018R1C1B6003990).
The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fbioe.2020.00472/full#supplementary-material
Supplementary Video. PNP soft robotic gripper grasping various objects.
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Keywords: PNP actuator, vacuum-based actuator, soft robotics, artificial muscles, fluidic actuators
Citation: Fatahillah M, Oh N and Rodrigue H (2020) A Novel Soft Bending Actuator Using Combined Positive and Negative Pressures. Front. Bioeng. Biotechnol. 8:472. doi: 10.3389/fbioe.2020.00472
Received: 29 February 2020; Accepted: 23 April 2020;
Ilkwon Oh, Korea Advanced Institute of Science and Technology, South Korea
Luigi Manfredi, University of Dundee, United Kingdom
Jinhan Jeon, Robert Bosch (SEA) Pte Ltd, Singapore
Copyright © 2020 Fatahillah, Oh and Rodrigue. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Hugo Rodrigue, rodrigue@skku.edu


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