The simplest mathematical method to estimate tortuosity is the arc-chord ratio: the ratio of the length of the curve (L) to the distance between the ends of it (C): Arc-chord ratio equals 1 for a straight line and is infinite for a circle.
ERS is a set of computer programs set to run in a specified order on the UNISYS Mainframe at the Enterprise. Computing Center in Martinsburg, West Virginia and the Enterprise Computing Center in Memphis, (ECC-MTB and. ECC-MEM) Tennessee. All ERS information is housed on the ERS database at each computing center.
ERD. Short for Emergency Repair Disk, an ERD is a diskette that creates backups of system files and settings and can help troubleshoot and fix issues for Windows NT and Windows 2000 users. The ERD is used in conjunction with the Windows repair option and will prompt for the diskette when needed. Note: The ERD is not to be confused with a standard boot diskette as it cannot be used alone.