RF SiP技术正转向无线设计主流

第1部分射频系统级封装(RF SiP,RF System-in-Pack-age)技术是一种对无线通信非常有用的封装平台,无线通信被如下事实所困,但由于目前SiP设计仍     

Object-oriented H.263 compatible video coding platform forconferencing applications

This paper describes a prototype video coding platform meant for the conception and testing of multimedia products such as next-generation videophones. The platform is largely based on ITU-T Recommendation H.263, with a number of additional object-oriented quality enhancement features which make it especially well suited for very low bit-rate coding of “head-and-shoulders” video material typical of real-time multimedia applications, video teleconferencing, and video telephony. These features consist of: (1) segmentation into objects of interest, (2) segmentation-based prefiltering, (3) model-assisted rate control, (4) adaptive vector quantization, and finally (5) segmentation-based postfiltering. In the spirit of Recommendation H.263, these enhancements are modular and can be selectively turned on or off, thereby enabling a wide variety of coding modes     

Localization of interferon-gamma and Ia-antigen in T cell line-mediated experimental autoimmune encephalomyelitis

This study reports the cellular localization of interferon-gamma (IFN-gamma) and MHC class II antigen (Ia) in the spinal cord of rats with experimental autoimmune encephalomyelitis induced by adoptive transfer of myelin basic protein-specific T cells. Numerous IFN-gamma-positive cells, stained with two different monoclonal antibodies against IFN-gamma, were present from days 3 to 7 after cell transfer. Their number was greatly reduced on day 10. A subpopulation of T cells was IFN-gamma positive. Moreover, a large number of ED1-positive macrophages contained IFN-gamma immunoreactivity. The transient presence of immune cells containing IFN-gamma immunoreactivity in experimental autoimmune encephalomyelitis suggests a pathogenic role of this cytokine in immune-mediated demyelination of the central nervous system.     

扁平工件的最佳淬火

Heimsoth淬火激冷工艺的优化以及接触板由钢制改用铜制后的实验结果表明,低合金钢和合金钢工件淬火厚度可分别达20 mm和100 mm,而且均匀、优质、几乎不发生变形.本文介绍和讨论了钢号为1.7228和1.3343的工件淬火后的平面度试验结果.采用钢制淬火激冷夹具工艺后工件的平面度达到最小平面度偏差.通过比较铜激冷夹具和钢激冷夹具的试验结果检验了理论模型的正确性.随后采用铜激冷夹具也取得了初步的试验结果,并将根据待淬火工件情况在淬火激冷夹具领域内对其进一步优化.这种新工艺将来也可应用于C45和C75等低合金钢和非合金钢的淬火.     

Development of a momentum microscope for time resolved band structure imaging

We demonstrate the use of a novel design of a photoelectron microscope in combination to an imaging energy filter for momentum resolved photoelectron detection. Together with a time resolved imaging detector, it is possible to combine spatial, momentum, energy, and time resolution of photoelectrons within the same instrument. The time resolution of this type of energy analyzer can be reduced to below 100 ps. The complete ARUPS pattern of a Cu(111) sample excited with He I, is imaged in parallel and energy resolved up to the photoelectron emission horizon. Excited with a mercury light source (h nu=4.9 eV), the Shockley surface state at the energy threshold is clearly imaged in k-space. Electron-electron interactions are observed in momentum space as a correlation hole in two-electron photoemission. With the high transmission and the time resolution of this instrument, possible new measurements are discussed: Time and polarization resolved ARUPS measurements, probing change of bandstructure due to chemical reaction, growth of films, or phase transitions, e.g., melting or martensitic transformations.     

Evolution strategies with cumulative step length adaptation on the noisy parabolic ridge

This paper presents an analysis of the performance of the (μ/μ,λ)-ES with isotropically distributed mutations and cumulative step length adaptation on the noisy parabolic ridge. Several forms of dependency of the noise strength on the distance from the ridge axis are considered. Closed form expressions are derived that describe the mutation strength and the progress rate of the strategy in high-dimensional search spaces. It is seen that as for the sphere model, larger levels of noise present lead to cumulative step length adaptation generating increasingly inadequate mutation strengths, and that the problem can be ameliorated to some degree by working with larger populations.     

Optimum tracking with evolution strategies

Evolutionary algorithms are frequently applied to dynamic optimization problems in which the objective varies with time. It is desirable to gain an improved understanding of the influence of different genetic operators and of the parameters of a strategy on its tracking performance. An approach that has proven useful in the past is to mathematically analyze the strategy's behavior in simple, idealized environments. The present paper investigates the performance of a multiparent evolution strategy that employs cumulative step length adaptation for an optimization task in which the target moves linearly with uniform speed. Scaling laws that quite accurately describe the behavior of the strategy and that greatly contribute to its understanding are derived. It is shown that in contrast to previously obtained results for a randomly moving target, cumulative step length adaptation fails to achieve optimal step lengths if the target moves in a linear fashion. Implications for the choice of population size parameters are discussed.     

Solidification of SiMo Nodular Cast Iron for High Temperature Applications

During the 1960s and 70s research was aimed at developing a material withstanding the ever higher temperatures in a combustion engine. This work resulted in what have later been named SiMo and D5S. SiMo is a nodular cast iron typically containing 4?C6?% Si and 0.5?C2?% Mo and can be used in temperatures up to 850?C860?°C. D5S is a nickel base material. High silicon and silicon?Cmolybdenum content improves the dimensional stability of ductile iron. Silicon increases the transformation temperature where austenite transforms to ferrite. Molybdenum partly segregates and freezes in intercellular regions, promoting carbides while during the solid state transformation molybdenum particles precipitate around grain boundaries. The solidified material shows a range of interesting structures and phases which will be presented.