Performance Improvisation of Cantilever-type Silicon Micro AccelerationSensors Using Stress Concentration Regions Technique

Acceleration sensors find applications in missile and competent munitions subsystems.Cantilever-type sensor's sensitivity and bandwidth are dependant on material properties of  thecantilever and structure of proof mass. It is always desired to design a sensor as sensitive aspossible but also maintaining higher bandwidth. In piezoresistive (cantilever-type) accelerometers,various techniques were employed by designers to enhance their sensitivity and bandwidth.Most of these techniques are usually focused on shape and size of either cantilever or proofmass. This paper presents a concept of creating stress concentration regions (SCRs) on thecantilever for enhancing its sensitivity. Five types of structures were simulated to study thebehaviour of piezoresistive sensors with SCRs implementation. Use of SCRs results in substantialincrease in the sensitivity, which is of the order of 1.85 times the nominal sensitivity. It was aimedat maximising sensor's performance factor, which is the product of sensor bandwidth andsensitivity. This study gives new dimension to the ways of improving performance of cantilever-type inertial piezoresistive sensor

Array E system description

This ATM describes the ALSEP Array E System. Its main purpose is to convey an understanding of the Power and Data Subsystems operation to a depth just above the circuit schematic level.written by A. Bedford, J. Kasser, D. Thomas ; approved by D. Fithian.General -- Structure/thermal subsystem -- Power subsystem -- Data subsystem -- Array "E" scientific instrument

Acoustic Emission Technology for High Power Microwave Radar Tubes

Microwave tubes used in high-power radar and communications systems are expensive and have an operating life of a few thousand hours. When one fails, it is generally impossible to determine the sequence of events that contributed to its failure. Previous investigators have designed microprocessor-based systems with as many as 11 sensors to monitor tube performance, provide tube protection, and record a comprehensive tube failure history. These systems are limited by the small amount of time available during the tube’s interpulse period for data buffering and fault analysis. They work well if the microwave tube is operated with 200 or fewer pulses per second. However, many tubes are operated at up to 1000 pulses per second. In this effort, an alternative nondestructive testing technique using acoustic emission (AE) was used for in-situ monitoring of normal and abnormal performance of radar tubes, including a magnetron, a klystron, and a traveling wave tube amplifier. This technique captures changes in radio frequency (RF) output pulses due to irregular operation and it is a real-time instantaneous in-situ indicator of the performance of microwave radar tubes. It also offers the possibility of developing built-in prognostic capabilities within the radar system to provide advanced warning of a system malfunction. Understanding the sequence of events leading to a tube failure allows for better maintenance, extends the operating life of the system, and results in significant cost avoidance