The heterojunction phototransistor (HPT) has applications as an optical detector/amplifier in receivers for fibre optic communications systems. It is well known that the provision of an external bias, either optically...
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The heterojunction phototransistor (HPT) has applications as an optical detector/amplifier in receivers for fibre optic communications systems. It is well known that the provision of an external bias, either optically or electrically, via a third (base) terminal, can enhance the performance of the HPT in terms of gain, speed of response and signal to noise ratio. This is due principally to an increase in emitter efficiency and a reduction in theRCtime constant of the emitter base junction. In the paper we show that crowding of the bias current and the signal current can affect very significantly the high frequency performance of phototransistors and will limit the advantage given by the external bias in three-terminal devices but improve the performance of two-terminal devices. The implications for the design of high speed phototransistors are discussed.
In this work a General Systems view of Applied Mechanics is presented. First, the main concepts and principles related to systems outlook are reviewed. Then, in the framework of systems thinking, the classical and cur...
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In this work a General Systems view of Applied Mechanics is presented. First, the main concepts and principles related to systems outlook are reviewed. Then, in the framework of systems thinking, the classical and currentdevelopments in thermodynamics are discussed. A section is also devoted to the study of mathematical isomorphisms among various mechanical systems/phenomena. A subsequent part of the work deals with the systems approach to mechanics including comparative study of elementalistic-holistic principles and methodologies together with a system approach to the Hamiltonian mechanics. A later section of the work is devoted to the application of systemic concepts in structural engineering. In this section, a systemic as well as reductionistic interpretation of structural analysis and design aspects is presented. The last section of this work deals with a discussion of instability phenomena in solids and fluids from a systemic viewpoint.
The experimental study of high-power electrical injuries requires special devices to protect personnel and data recording instruments. A power distribution system is described which was designed to apply 500-20000 v a...
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The experimental study of high-power electrical injuries requires special devices to protect personnel and data recording instruments. A power distribution system is described which was designed to apply 500-20000 v and currents up to 100 A to an experimental preparation and a measurement system for recording 0.02-200.0 v at local sites in the preparation. Data collection and storage are automated with analog and digital devices that minimize personnel contact. For personnel safety, all recording instruments are isolated from the power distribution system by battery-driven standby power supplies and from the experimental high voltages by fiber optic data links. current-triggering and- interruption mechanisms allow variable-duration voltage applications as short as 25 ms. These applications are also synchronized to the electrocardiogram and can be made to occur during any part of the cardiac cycle.< >
In recent years reinforced thermoplastics have been replacing metals in applications spanning the automotive, aerospace, electrical, electronic, and consumer product markets. Because most polymers are inherently flamm...
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In recent years reinforced thermoplastics have been replacing metals in applications spanning the automotive, aerospace, electrical, electronic, and consumer product markets. Because most polymers are inherently flammable, various regulatory agencies (FAA, Dept. of Transportation, etc.), have mandated the compliance of design materials to specific flammability tests. By far the most stringent and most widely accepted flammability resistance test is the Underwriters' Laboratories Standard for Safety UL-94 for electrical devices. UL-94 classifies materials according to the duration of flaming and non-flaming (glow) combustion following ignition and tendency to drip flamming particles;a UL-94v-0 listing indicates a 0-5 second flame duration, 0-25 second afterglow, and no flaming drips which ignite cotton. In this study a series of glass reinforced composites which meet UL-94v-0 flammability requirements are examined for relative performance in meeting application design requirements.
A new 8cm-diam ion source has been fabricated for ion-assisted deposition and sputtering. This source empolies a divergent magnetic field discharge chamber, and the field is generated by a permanent magnet located at ...
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A new opticaldesign has been incorporated into an instrument for use in digital imaging and quantitative analysis of fundus images. By using an opticaldesign program, in combination with custom electronics, we have ...
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An accurate formula for calculating color wave aberration is provided, and the difference between the aberration computed by Conrady's wrong formula and the real aberration is pointed out. At the same time, a new ...
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The focusing grating coupler (FGC) can be constructed using holographic techniques. Due to the wavelength scaling between the construction of the FGC and its final enduse operation, aberrations exist in the final spot...
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At present, whether the economic benefit of a designed optical system is high is an important mark to judge the opticaldesign level. The "Information - Price Ratio", the ratio of the spatial information qua...
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In recent years, the need for wide-angle, unobscured, all-reflecting opticaldesigns has increased significantly. This paper takes a look at several of these types of designs, and compares their performance and limita...
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