Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings最新文献_第2页

Poynting's theorem and time-harmonic radiators 波印亭定理和时谐辐射

Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings Pub Date : 1994-02-05 DOI: 10.1109/AERO.1994.291188

D. M. Grimes, C. Grimes

引用次数: 3

Not all programmers are created equal 并不是所有的程序员都是平等的

Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings Pub Date : 1994-02-05 DOI: 10.1109/AERO.1994.291203

G., Edward Bryan

引用次数: 19

Current carrying capacity of dendrites 枝晶载流能力

Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings Pub Date : 1994-02-05 DOI: 10.1109/AERO.1994.291179

W. Bjorndahl, J. Lau

{"title":"Current carrying capacity of dendrites","authors":"W. Bjorndahl, J. Lau","doi":"10.1109/AERO.1994.291179","DOIUrl":"https://doi.org/10.1109/AERO.1994.291179","url":null,"abstract":"Dendrites are sometimes found on electronic hardware during failure analysis or trouble shooting activities. Problems due to dendrite formation can vary from catastrophic failure to occasional electronic glitches. If a dendrite is thought of as a fuse in a circuit, then it is apparent that it can have, depending on size, a wide range of current carrying capability. Mathematical modeling and experimental analyses were conducted to determine the reasons for the wide range of observed behavior. Mathematical modeling indicates that the resistivity of the dendrite and the thermophysical characteristics of the substrate on which it is grown determine its current carrying capacity. More specifically, the modeling indicates that maximum dendrite size and time to failure are determined by the power loss within the dendrite and the rate at which heat can be transferred away from the dendrite. Small dendrites are stable and can grow until they reach a size at which internal heat generation cannot be accommodated by the heat loss due to conduction through the substrate. Dendrites in low voltage applications on substrates with high thermal diffusivity are more likely to lead to failures with high power loss, whereas dendrites in high voltage applications on low thermal diffusivity substrates (e.g. tin on glass/epoxy circuit board material) are more likely to lead to high resistance shorts. Experimental results and failure analysis observations agree qualitatively and semi-quantitatively with the results of the idealized dendrite model.<<ETX>>","PeriodicalId":223269,"journal":{"name":"Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129677975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

One time transient failure investigation 一次性瞬态失效研究

Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings Pub Date : 1994-02-05 DOI: 10.1109/AERO.1994.291183

L. Mallette, J. Varney

引用次数: 0

A high performance critical section protocol for distributed systems 分布式系统的高性能临界区协议

Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings Pub Date : 1994-02-05 DOI: 10.1109/AERO.1994.291207

R. R. Seban

{"title":"A high performance critical section protocol for distributed systems","authors":"R. R. Seban","doi":"10.1109/AERO.1994.291207","DOIUrl":"https://doi.org/10.1109/AERO.1994.291207","url":null,"abstract":"Parallel and distributed processing is a system level approach used to develop high performance and fault tolerant systems. For example, an airborne or a space platform computational system consists of several subsystems (possibly replicated for speed and reliability) and sometimes optimized to perform specific tasks such as flight control, communications, information display, or telemetry. The computation in a distributed system is modeled as a collaboration of interacting processes. When processes share information in a read/write fashion a problem may arise. Although each individual process performs its computation correctly, the result of the computation of the distributed system may be incorrect because of an improper sharing of the information. In this paper we present a new high performance critical section protocol designed for distributed systems with general topologies where the communication network is implemented as point-to-point physical links in contrast to a shared access bus. Distributed systems can be modeled by a graph G(V, E) where V denotes the set of processors (nodes) and E the set of communication links (edges). n denotes the number of processors, D(G) the diameter of G, and D(T) the diameter of the spanning tree. An important measure of the protocol performance is the network traffic caused by a single access to the critical section. Another important measure of performance is the time required to access the critical section/spl minus/in the absence of other requests/spl minus/the cs-access time. The proposed protocol has a better network traffic performance and (depending on the topology) a better or equal cs-access time performance than previously published fully distributed protocols. The protocol bounds the clock and message sizes in well designed systems using a distributed predictive \"clock squashing\" mechanism. Other protocols, even for well designed systems, have unbounded clocks and hence unbounded messages sizes.<<ETX>>","PeriodicalId":223269,"journal":{"name":"Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125906233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Fuzzy logic vs traditional approaches to the design of microcontroller-based systems 模糊逻辑与传统方法设计基于微控制器的系统

Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings Pub Date : 1994-02-05 DOI: 10.1109/AERO.1994.291206

A. Jackson

{"title":"Fuzzy logic vs traditional approaches to the design of microcontroller-based systems","authors":"A. Jackson","doi":"10.1109/AERO.1994.291206","DOIUrl":"https://doi.org/10.1109/AERO.1994.291206","url":null,"abstract":"The use of fuzzy logic for closed loop control is compared to the more traditional approaches of zero-pole placement in the z-plane and the choice of PID (proportional, integral, differential) parameters. A common type of positioning system is used as an example to illustrate these different approaches and to allow practical comparisons. Results of a simulation study of the model system, using specific implementations of the three control techniques, show that fuzzy logic can be used to achieve a degree of compensation that is nearly as good as that achieved by more conventional techniques. The fuzzy logic approach requires more code, hence, more power on the part of the microcontroller, but it does not require that the designer have a knowledge of feedback control theory. Because fuzzy logic is a straightforward approach, based upon practical knowledge of the system to be controlled, its use has some advantages over the other approaches if an analytic model of the system is difficult to construct. Certain demands are placed upon the microcontroller in all three cases, and these are discussed here in some detail. Two popular microcontrollers, the MC68HC16 and MC68332, are examined to explore their individually unique features that make them particularly suitable for one or the other of the control schemes studied.<<ETX>>","PeriodicalId":223269,"journal":{"name":"Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117292612","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10

Physical analysis of dendrites within conformal coat 保形涂层内枝晶的物理分析

Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings Pub Date : 1994-02-05 DOI: 10.1109/AERO.1994.291181

J. Novak

引用次数: 0

A high data rate electro-optic phase modulator driver for a coherent optical communications application 用于相干光通信应用的高数据速率电光相位调制器驱动器

Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings Pub Date : 1994-02-05 DOI: 10.1109/AERO.1994.291193

C. J. Grant, R. Mueller, N. Mysoor

引用次数: 0

EMI shielding characteristics of permalloy multilayer thin films 坡莫合金多层薄膜的电磁干扰屏蔽特性

Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings Pub Date : 1994-02-05 DOI: 10.1109/AERO.1994.291194

C. Grimes

{"title":"EMI shielding characteristics of permalloy multilayer thin films","authors":"C. Grimes","doi":"10.1109/AERO.1994.291194","DOIUrl":"https://doi.org/10.1109/AERO.1994.291194","url":null,"abstract":"High permeability magnetic films used for shielding or absorption of electromagnetic interference (EMI) are commonly built in a multilayer stack to maximize the permeability by eliminating or reducing the number of domain walls. The choice of spacer material is driven by the fact that electrically insulating spacer materials reduce eddy currents which cause incident waves to be reflected and not absorbed. Design of frequency specific EMI absorbers or shields requires knowledge of the rf permeability of magnetic multilayer films. We examine the complex, rf permeability spectra and low frequency magnetic field shielding characteristics of DC planar magnetron sputtered Fe/sub 19/Ni/sub 81/ multilayer films as a function of spacer material, number of layers, and thickness of the spacer and magnetic layer. The permeability spectra are measured using a permeameter over the frequency range 5 MHz to 100 MHz. The spacer materials examined include several metals and metal alloys, the corresponding oxides, silicon, and silicon nitride. Spacer layers made of Si/sub 3/N/sub 4/ result in permeability spectra with the highest permeability magnitudes, while copper spacers result in the highest shielding levels. For a fixed number of multilayer pairs and constant spacer layer thickness making the magnetic layer thicker tends to increase the permeability magnitude, and lower the resonance frequency. We find that for electrically insulating spacer layers the same characteristic permeability spectra can be obtained by either increasing the number of layers or increasing the thickness of the magnetic layer.<<ETX>>","PeriodicalId":223269,"journal":{"name":"Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131372016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 18

Conformal antennas for smart cars 智能汽车的共形天线

Proceedings of 1994 IEEE Aerospace Applications Conference Proceedings Pub Date : 1994-02-05 DOI: 10.1109/AERO.1994.291187

R. Munson

引用次数: 3