Development of limb volume measuring system

The mechanisms underlying the reductions in orthostatic tolerance associated with weightlessness are not well established. Contradictory results from measurements of leg volume changes suggest that altered venomotor tone and reduced blood flow may not be the only contributors to orthostatic intolerance. It is felt that a more accurate limb volume system which is insensitive to environmental factors will aid in better quantification of the hemodynamics of the leg. Of the varous limb volume techniques presently available, the ultrasonic limb volume system has proven to be the best choice. The system as described herein is free from environmental effects, safe, simple to operate and causes negligible radio frequency interference problems. The segmental ultrasonic ultrasonic plethysmograph is expected to provide a better measurement of limb volume change since it is based on cross-sectional area measurements

Design and fabrication of general purpose 8085 card and develop various interfacing cards useful in education of electronics

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The development of Advance Experiments useful to the students of Electronics field

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Triggering Synchronization Of Multiple Usb 3.0 Devices Using Isochronous Timestamp Packet

In test and measurement, synchronizing multiple devices to timely coordinate data acquisition is crucial. This is due to the limited number of channels on a single device and the need for mixed-signal channels. Currently, various techniques have been proposed for triggering and synchronization among multiple devices such as GPIB, VXI, PXI/PXIe and LXI. However, they are expensive and need large footprint and additional cable or hardware to set up. Due to that, with the low cost and easy-to-setup USB 2.0, it is enhanced to have synchronization ability. There are various synchronization methods in USB 2.0 such as software-timed trigger, external hardware trigger and USB-inSync. The software-timed trigger is purely implemented in software and has high trigger delay, which is up to microseconds. Besides that, for both external hardware trigger and USB-inSync, they can achieve up to nanoseconds of synchronization precision. However, both of those methods need extra hardware or setup to synchronize multiple devices. In order to overcome these drawbacks from the existing techniques, a trigger algorithm is proposed based on the study of USB 3.0 technology. The Isochronous Timestamp Packet (ITP) in USB 3.0 is used as the main component in the trigger algorithm. Without any hardware implementation, the trigger algorithm is able to trigger multiple USB 3.0 devices with a trigger delay around 280 ns. In addition, the trigger algorithm can support up to maximum three consecutive connected hubs without affecting the performance. In short, the trigger algorithm had improved the trigger delay from conventional software-timed trigger by 99.7% and without any hardware implementation it is easier to set up compared to external hardware trigger

Bicameralism and Government Formation

In this paper we present a structural approach to the study of government formation in multi-party parliamentary democracies. The approach is based on the estimation of a stochastic bargaining model which we use to investigate the effects of specific institutional features of parliamentary democracy on the formation and stability of coalition governments. We then apply our methodology to estimate the effects of governmental bicameralism. Our main findings are that eliminating bicameralism does not affect government durability, but does have a significant effect on the composition of governments leading to smaller coalitions. These results are due to an equilibrium replacement effect: removing bicameralism affects the relative durability of coalitions of different sizes which in turn induces changes in the coalitions that are chosen in equilibrium.Political stability, Government formation, Government dissolution, Bicameralism, Comparative constitutional design

The STAR MAPS-based PiXeL detector

The PiXeL detector (PXL) for the Heavy Flavor Tracker (HFT) of the STAR experiment at RHIC is the first application of the state-of-the-art thin Monolithic Active Pixel Sensors (MAPS) technology in a collider environment. Custom built pixel sensors, their readout electronics and the detector mechanical structure are described in detail. Selected detector design aspects and production steps are presented. The detector operations during the three years of data taking (2014-2016) and the overall performance exceeding the design specifications are discussed in the conclusive sections of this paper

Fault tolerance in digital controllers using software techniques

Microprocessor based systems for controlling gas supplies require very high levels of reliability for safety reasons. Non-redundant systems are considered to be inadequate, and an alternative approach is necessary. in digital systems, transient faults are as much as fifty times more common than permanent faults. Therefore mechanisms which allow for recovery from transients will provide large Improvements in reliability. However, to enable effective design of recovery mechanisms it Is necessary to understand failure modes. The results from practical interference tests, designed to simulate transient faults, are presented. They show that corruption to the correct flow of program execution is a common failure, and that subsequent instruction fetches can be performed from any of the memory locations. Under these conditions any value of operation code can be Interpreted as an instruction, including those undeclared by the manufacturers. Four commonly used microprocessors are investigated to establish the functions of the undeclared codes, and other undeclared operations are revealed. Analyses on the sequence of events following a random jump into the four main memory types of data, program, unused and input areas, are presented. Recovery from this type of execution can be achieved by the addition of restart codes into the areas, so that execution can transfer to a recovery routine. The effect of this mechanism on the recovery process is investigated. Finally, some methods of testing systems, to check the levels of reliability improvement obtained by these techniques, are considered

The implementation of a LAN

Includes bibliography.The subject of this thesis concerns the development of a Local Area Network (LAN) for the Department of Electrical and Electronic Engineering at the University of Cape Town. Motivation for this project was as a result of the ever increasing demands placed on the department's micro-computer training facilities by larger student intakes. The original training system consisted of a PDP 11/23 mini-computer connected via 9600 baud asynchronous links to 11 U.C.T. built micro-computers. This network topology was limiting in three ways: 1. It was slow because of the 9600 baud links and because the PDP was doing a large proportion of the processing.2. High-leve 1 software development tools for the PDP were too expensive and would over-load the computer. Because the micro-computers have no operating system but only an "in-house" monitor program which is not able to support any high-level language utility, all high-level software tools would have to be individually developed for this particular environment. 3. Switching was impractical. Because the PDP was the hub of the network all communication between computers had. to pass through it. This switching would lead to a greater processing load on the PDP, thus further degrading its performance. A two pronged attack was used to overcome these weaknesses: firstly, by designing a high-speed (1 Mbps) LAN to provide communications between a PDP 11/23 and up to 30 U.C.T. built micro-computers, faster inter-computer communication as well as switching and resource sharing was facilitated. Secondly, by customizing an operating system for the micro-computers, standard high-level software development tools could be used on these computers, consequently reducing the PDP's processing load

Education Interrupted: The Growing Use of Suspensions in New York City's Public Schools

The New York Civil Liberties Union analyzed 10 years of discipline data from New York City schools, and found that:*The total number of suspensions in New York City grew at an alarming rate over the last decade: One out of every 14 students was suspended in 2008-2009; in 1999-2000 it was one in 25. In 2008-2009, this added up to more than 73,000 suspensions.*Students with disabilities are four times more likely to be suspended than students without disabilities.*Black students, who comprise 33 percent of the student body, served 53 percent of suspensions over the past 10 years. *Black students with disabilities represent more than 50 percent of suspended students with disabilities.*Black students also served longer suspensions on average and were more likely to be suspended for subjective misconduct, like profanity and insubordination.*Suspensions are becoming longer: More than 20 percent of suspensions lasted more than one week in 2008-2009, compared to 14 percent in 1999-2000. The average length of a long-term suspension is five weeks (25 school days).*Between 2001 and 2010, the number of infractions listed in the schools' Discipline Code increased by 49 percent. During that same period, the number of zero tolerance infractions, which mandate a suspension regardless of the individual facts of the incident, increased by 200 percent.*Thirty percent of suspensions occur during March and June of each school year

An electronically focused multiple beam side scan sonar

Phased arrays have been in use since World War II but their commercial application has been constrained by the bulk and cost of the beam forming system. High resolution side scan sonar systems have many operational parameters that may only be extended with the aid of phased arrays, the resolution and the imaging rate being the most important. This thesis describes a microprocessor controlled dynamically focused side scan sonar where high resolution and high image acquisition rates are achieved. Dynamic focusing prevents the depth of field limitations of fixed focus arrays by updating the array phases at regular intervals so as to create a focal point which recedes from the array in synchronism with the returning echoes from the transmitted pulse. A high image acquisition rate is achieved through the simultaneous formation of multiple beams. Using a microprocessor as a low-cost controller demands rapidly executable software and a little specialized hardware. Programmable quadrature phase shifters give phase and amplitude control. A beam forming board combines the phase shifted signals into a beam and samples it. A 'time domain multiplexed' transmitter solves the problem of efficient insonification of swaths. The system timing is complex; while image samples are captured data is formatted and presented for recording on a chart recorder. This occurs in real-time, while the focus of each of the multiple beams is changed almost every two meters. Tank tests of the completed system provide confirmation of the resolution predicted with theory and computer simulation. Sea trials confirm that resolution close to that predicted may be obtained under operational circumstances. The results obtained fully justify the assertion that low cost microprocessor controlled dynamically focused multiple beam phased arrays are both an attainable and an attractive solution to the problems faced by the designer of high resolution side scan sonar systems