Электрохимическая миграция: этапы и профилактика

The modern trend of miniaturization of electronics has also affected the aviation industry. With each new generation of aviation electronics (avionics), the layout of electronic components becomes smaller and smaller. This led to a significant complication of all electronic components of avionics in general, as well as compaction topology of printed circuit board (PCB) used in avionics, in particular. Any complication of electronic equipment, and especially important facilities, leads to increased requirements for reliability. Given that the aircraft equipment is operated almost constantly in extreme conditions, even the slightest probability of failure is unacceptable. That is why the physical reliability of avionics is so important. One of the factors significantly reducing the physical reliability of aviation electronics is electrochemical migration.Electrochemical migration can lead to failures in the operation of aviation electronics, to its complete failure, and even to a fire outbreak on the aircraft. Now the electrochemical migration is explored badly. Only the factors causing it and the consequences of electrochemical migration are determined, and the existing way of struggle it is either ineffective or significantly increase the weight and cost of aircraft equipment set, so that their use becomes impractical.This article presents experimental studies of the kinematics of electrochemical migration, the consequences of its occurrence, as well as, the way of struggle of the occurrence of electrochemical migration with the analysis of experimental data.Современная тенденция миниатюризации электроники затронула и авиационную промышленность. С каждым новым поколением авиационной электроники (авионики) компоновка электронных узлов становится все меньше и меньше. Это привело к значительному усложнению всех электронных узлов авионики в целом, а также уплотнению топологии печатных плат, использующихся в авионике в частности. Любое усложнение электронной аппаратуры, а особенно аппаратуры ответственного назначения, приводит к повышению требований к надежности. Учитывая, что авиационная аппаратура эксплуатируется практически постоянно, в экстремальных условиях, даже малейшая вероятность возникновения сбоя или отказа недопустима. Именно поэтому физическая надежность авионики настолько важна. Одним из факторов, существенно снижающим физическую надежность авиационной электроники, является возникновение электрохимической миграции.Электрохимическая миграция способна привести к сбоям в работе авиационной электроники, к ее полному отказу, а также даже к возгоранию на борту летательного аппарата. На сегодняшний день явление электрохимической миграции изучено достаточно плохо. Определены лишь факторы, вызывающие ее, и последствия электрохимической миграции, а существующие способы борьбы с этим явлением либо неэффективны, либо значительно увеличивают вес и стоимость бортовой аппаратуры настолько, что их использование становится нецелесообразным.В данной статье приводятся экспериментальные исследования кинематики явления электрохимической миграции, последствий ее возникновения, а также с учетом проведенного анализа экспериментальных данных предложен способ борьбы с возникновением явления электрохимической миграции

Evidence for a high-energy cosmic-ray spectrum cutoff

Journal ArticleWe report a measurement of the ultrahigh-energy cosmic-ray spectrum using an atmospheric fluorescence technique for extensive-air-shower detection. The differential spectrum between 0.1 and 10 EeV (1 EeV = 10^18 eV) is well fitted by a power law with slope 2.94 ±0.02. Above 10 EeV evidence is presented for the development of a spectral " bump " followed by a cutoff at 70 EeV

Limits on deeply penetrating particles in the >10^17 eV cosmic-ray flux

Journal ArticleWe report on a search for deeply penetrating particles in the > 10^17 eV cosmic-ray flux using the University of Utah Fly's Eye detector. No such events have been found in 6 x 106 sec of running time. We consequently set limits on the following: quark matter in the primary cosmic-ray flux, high-energy long-lived weakly interacting particles produced in proton-air interactions, such as τ's; astrophysical neutrino flux; and other hypothetical high-energy weakly interacting components of the cosmic-ray flux such as photinos

Extremely high energy cosmic rays and the Auger Observatory

Over the last 30 years or so, a handful of events observed in ground-based cosmic ray detectors seem to have opened a new window in the field of high-energy astrophysics. These events have energies exceeding 5x10**19 eV (the region of the so-called Greisen-Zatsepin-Kuzmin spectral cutoff); they seem to come from no known astrophysical source; their chemical composition is mostly unknown; no conventional accelerating mechanism is considered as being able to explain their production and propagation to earth. Only a dedicated detector can bring in the high-quality and statistically significant data needed to solve this long-lasting puzzle: this is the aim of the Auger Observatory project around which a world-wide collaboration is being mobilized.Comment: 14 pages, no figures, Latex, to be published in Proc. of the 7th Int. Workshop on Neutrino Telescopes (Venice 27/2-1/3 1996

Disappointing model for ultrahigh-energy cosmic rays

Data of Pierre Auger Observatory show a proton-dominated chemical composition of ultrahigh-energy cosmic rays spectrum at (1 - 3) EeV and a steadily heavier composition with energy increasing. In order to explain this feature we assume that (1 - 3) EeV protons are extragalactic and derive their maximum acceleration energy, E_p^{max} \simeq 4 EeV, compatible with both the spectrum and the composition. We also assume the rigidity-dependent acceleration mechanism of heavier nuclei, E_A^{max} = Z x E_p^{max}. The proposed model has rather disappointing consequences: i) no pion photo-production on CMB photons in extragalactic space and hence ii) no high-energy cosmogenic neutrino fluxes; iii) no GZK-cutoff in the spectrum; iv) no correlation with nearby sources due to nuclei deflection in the galactic magnetic fields up to highest energies.Comment: 4 pages, 7 figures, the talk presented by A. Gazizov at NPA5 Conference, April 3-8, 2011, Eilat, Israe

Тестирование скрытых дефектов в соединениях

Electronic instrumentation has a constant growth density layout and functionality. This entails an increase in the density of interconnection elements by increasing their number and reducing the size of it. The growing cost of interconnection structures (printed circuit boards, printing and wired mounting) associated with their complexity and increase of their reliability requirements, result in the search of new and improved non-destructive diagnostic methods and means of control. However, the existing methods do not allow control interconnects with sufficient certainty to identify a significant number of hidden defects. This class of defects can be diagnosed by means of non-destructive testing of interconnections, based on the detection of controlled circuit reaction to a current. The paper describes the principles for calculating the current to exercise that control.Электронное приборостроение находится в состоянии постоянного роста плотности компоновки и функциональности. Это влечет за собой рост плотности элементов межсоединений за счет увеличения их количества и уменьшения размеров. Возрастание стоимости конструкций межсоединений (печатных плат, печатного и проводного монтажа), связанное с их усложнением и возрастанием требований к надежности, обуславливает поиск новых и совершенствование существующих неразрушающих диагностических методов и средств контроля. Однако, существующие методы контроля межсоединений не позволяют с достаточной достоверностью выявить значительную часть скрытых дефектов. Такие дефекты могут быть диагностированы при помощи неразрушающего контроля соединений, основанного на регистрации реакции контролируемых цепей на воздействие импульса тока. В статье описываются принципы расчета параметров импульса тока и способ реализации такого контроля

Java-MaC A Run-time Assurance Tool for Java Programs

AbstractWe describe Java-MaC, a prototype implementation of the Monitoring and Checking (MaC) architecture for Java programs. The MaC architecture provides assurance about the correct execution of target programs at run-time. Monitoring and checking is performed based on a formal specification of system requirements. MaC bridges the gap between formal verification, which ensures the correctness of a design rather than an implementation, and testing, which only partially validates an implementation. Java-MaC provides a lightweight formal method solution as a viable complement to the current heavyweight formal methods. An important aspect of the architecture is the clear separation between monitoring implementation-dependent low-level behaviors and checking high-level behaviors against a formal requirements specification. Another salient feature is automatic instrumentation of executable codes. The paper presents an overview of the MaC architecture and a prototype implementation Java-MaC