Nonlinear Kerr interactions between modulated waves propagating ina single-mode fiber

The interactions induced by the nonlinear refractive index in a single-mode optical fiber (Kerr effect) between a modulated wave and a carrier wave have been investigated for amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK). The theoretical analysis, based on a time-domain solution, exploits the well-known formalism of self-phase modulation to describe the propagation of the input electric field in the fiber. The theoretical results were validated experimentally for amplitude- and phase-modulated waves with heterodyne detection techniques. These experiments mimic a coherent transmission system and allow the measurement of the spectrum of each of the waves that participate in the nonlinear interaction     

Electrochemical impedance spectroscopy of a free-standing oxide film

The corrosion of low carbon steel in natural sea-water is characterized by the formation and growth of compact and thick layers composed of oxides, insoluble salts and organic materials. These layers are the result of corrosion processes induced by local environmental conditions, water oxygen supply; ionic species; bacteria and organic matter. The exchange of various species (ions, molecules, gas) between sea-water and the rust layers or the metal depends both on the kinetics of the Faradaic reactions of the entities with either the oxides or the metal, as well as on their transport properties through the different strata of the rust layers. In this work, an impedance study was carried out using the 4-electrodes cell arrangement with corrosion products picked up on steel sheet piling immersed for 25 years and analyzed as free standing membranes. This new approach is a good way to reach the specific transport and transfer properties of the oxide without being blurred by the metal influence. The physical model developed in this work was based on a transmission line, and accurately described the experimental diagrams. The electronic resistivity of the oxide layer, its porosity, the mean pore size and the reaction kinetics parameters could be determined from the fittings.     

Penalty interference of nonlinear intra-channel effects and PMD inultra high-speed TDM systems

Penalty interference of nonlinear propagation impairments and polarisation mode dispersion (PMD) caused signal distortions is experimentally investigated     

IEEE standard 802.16: a technical overview of theWirelessMANTM air interface for broadband wirelessaccess

The broadband wireless access industry, which provides high-rate network connections to stationary sites, has matured to the point at which it now has a standard for second-generation wireless metropolitan area networks. The IEEE standard 802.16, with its WirelessMAN^TM air interface, sets the stage for widespread and effective deployments worldwide. This article overviews the technical medium access control and physical layer features of this new standard     

Why are experts not better in judging the danger of filmed traffic conflicts?

Earlier studies on the subject of subjective judgment of traffic conflicts showed that untrained subjects can reliably judge the dangerousness of filmed traffic conflicts. It was concluded that these judgements were based on a concept of dangerousness. In line with these findings two experiments were conducted. Experiment 1 tested the hypothesis that traffic experts (traffic engineers trained to evaluate and improve traffic safety) and lay people use the same concept of dangerousness when judging filmed conflicts. Experiment 2 investigated which aspects of the conflicts are considered by experts when making these judgements. The results show that (i) experts and lay people are equally reliable in judging traffic conflicts, (ii) experts base their judgement on the same concept of dangerousness, (iii) experts do not base their judgement on aspects that they themselves regard as important for the conflict, (iv) a weak relation is found between violations of traffic regulations and judgements of dangerousness.     

High-reliability GaAs-AlGaAs HBTs by MBE with Be base doping andInGaAs emitter contacts

The authors have developed a modified MBE growth process to produce high-gain n-p-n GaAs-AlGaAs heterojunction bipolar transistors (HBTs) with a mean time to failure (MTTF) of 1.5×10⁸ h at 125°C. Beryllium incorporation and diffusion are controlled through a combination of reduced substrate temperature and increased As/Ga flux ratio during MBE growth, resulting in extremely stable HBT profiles. The authors also demonstrate graded InGaAs surface layers with nonalloyed refractory metal contacts that significantly improve ohmic reliability compared to alloyed AuGe contacts. The ability to produce robust HBTs by MBE is critically important to this technology     

Efficient design/simulation algorithms for simultaneous switching noise in leadframe packages

 Two new modeling and simulation approaches for Simultaneous Switching Noise (SSN) are described and compared to “brute force” simulation by SPICE. Both simulation accuracy and simulation run-time are considered. The two new approaches are: 1) the “effective inductance” method, in which an approximate, very efficient method of extracting an SSN L _eff  is utilized; and 2) the “macromodel” method, in which the complex inductance network responsible for SSN is represented by only a few dominant poles in the frequency domain and the time domain response is obtained by an efficient convolution algorithm. Both approaches are shown to be accurate and fast, but only the effective inductance algorithm is robust in numerical convergence. Received: 19 March 1997 / Accepted: 25 March 1997     

A standardized method for CMOS unit process development

The multipurpose mask set described, which consists of three stepper reticles, contains 95% of all test structures required for CMOS process development and random defect detection, thereby dramatically reducing the stepper reticle inventory and the frequency of reticle changes. Realizing the mask set by two dozen standard unit processes minimizes the feedback loop for defect density data, parametric data and unit process data