A Nested Multistage Adaptive Beamformer with a Low Complexity Under the Correlated Signal Environment

A multistage adaptive beamformer for wireless communications is proposed. The beamformer adopts a novel nested system architecture to reduce the system complexity and to achieve the system optimization which is carried out independently at each stage. It is shown that this method attains an improved performance in comparison to another competitive method.     

Dependence of photoluminescence spectra of epitaxial Pb1 ? xEuxTe (0 ≤ x ≤ 0.1) alloy layers on conditions of growth

The photoluminescence spectra of the Pb_{1 − x} Eu _x Te (0 ≤ x ≤ 0.1) alloy are studied at low temperatures. Epitaxial layers were grown by molecular-beam epitaxy at different temperatures. Along with the basic line corresponding to interband radiative recombination, additional emission lines are observed in the low-energy region of the spectra. Some nonuniformities are observed at the sample surface (within an area smaller than 1% of the total surface area). The concentration and size (1–10 μm) of the nonuniformities decrease with increasing temperature of growth. The additional emission lines are attributed to local nonuniformities in the layer. The dependence of the band gap of the Pb_1−x Eu _x Te (0 ≤ x ≤ 0.1) alloy on the composition parameter x is determined at 77.4 K. The dependence is nonlinear and adequately described by the relation E _g [eV] = 0.213 + 4.8x − 18.4x ².     

Diffraction of H0m and E0m modes by a system of axially symmetric discontinuities in a coaxial circuit

Diffraction of axially symmetric H _0m and E _0m modes by a system of annular slots in the hollow inner conductor of a coaxial waveguide is considered. The space inside a slot and between the slots is filled with a dielectric. Diffraction of H _0m and E _0m modes by the end of a semiinfinite circular waveguide placed coaxially in a circular waveguide of larger diameter is solved as the key problem. The obtained solution is used in the analysis of structures with a finite number of equispaced discontinuities. The solution is obtained with the operator approach. Dependences of the reflection coefficient of this structure on the slot width and the spacing of discontinuities are analyzed.     

HomePNA通信中的技术与应用

正如局域网 (LAN)是为了满足企业内多用户互连和资源共享 ,为满足家庭中多种数字设备互连和资源共享 ,家庭电话线网设备 (HomePNA)应运而生。文章叙述了HomePNA通信中所需的技术与应用。     

Neural Network Modelling with Input Uncertainty: Theory and Application

It is generally assumed when using Bayesian inference methods for neural networks that the input data contains no noise. For real-world (errors in variable) problems this is clearly an unsafe assumption. This paper presents a Bayesian neural network framework which accounts for input noise provided that a model of the noise process exists. In the limit where the noise process is small and symmetric it is shown, using the Laplace approximation, that this method adds an extra term to the usual Bayesian error bar which depends on the variance of the input noise process. Further, by treating the true (noiseless) input as a hidden variable, and sampling this jointly with the network's weights, using a Markov chain Monte Carlo method, it is demonstrated that it is possible to infer the regression over the noiseless input. This leads to the possibility of training an accurate model of a system using less accurate, or more uncertain, data. This is demonstrated on both the, synthetic, noisy sine wave problem and a real problem of inferring the forward model for a satellite radar backscatter system used to predict sea surface wind vectors.     

Optical properties of quantum-confined heterostructures based on GaPxNyAs1 ? x ? y alloys

The results of calculations of the band gap in GaP _x N _y As_{1 − x − y} alloys and the estimated parameter of hybridization of the conduction band in GaP and the localized level of nitrogen are reported. The optical properties of quantum-confined heterostructures based on GaP _x N _y As_{1 − x − y} alloys synthesized on the GaP (100) substrate surface are studied by photoluminescence measurements in the temperature range of 15–300 K. The heterostructures consist of GaP_0.814N_0.006As_0.18 quantum wells separated by GaP barrier layers. The well width and the barrier thickness are 5 nm. Heterostructures with different numbers of periods are considered. On optical excitation of the structures, an intense photoluminescence line is observed in the spectral range 620–650 nm. The photoluminescence spectra of the GaP_0.814N_0.006As_0.18/GaP quantum wells are profoundly broadened because of the inhomogeneity of the quaternary alloy in composition. It is established that the increase in the number of quantum well layers from 10 to 25 does not results in degradation of the photoluminescence properties of the heterostructures. The results of the study support the view that it is possible to produce efficient optoelectronic devices on the basis of GaP _x N _y As_{1 − x − y} alloys.     

909工程超大规模集成电路厂房高纯气体管道的应用

简述909工程高纯气体管道系统设计中气体管道材料的选用,及设计对管道的施工安装,试压及验收的要求。     

洁净手术部空调系统设计探讨

总结了医院洁净手术部空调系统常见的设计方法,介绍了手术部控制气流流向和压力分布方面的特点,比较了洁净手术室空气处理的不同过程,提出了正负压转换的思路。     

Matched Filter Based Spectrum Sensing When Primary User Has Multiple Power Levels

In this paper,we investigate the matched filter based spectrum sensing in a more reasonable cognitive radio(CR) scenario when the primary user(PU) has more than one transmit power levels,as regulated in most standards,i.e.,IEEE 802.11 Series,GSM,LTE,LTE-A,etc.This new multiple primary transmit power(MPTP) scenario is specialized by two different targets:detecting the presence of PU and identifying the power level.Compared to the traditional binary sensing where only the presence of PU is checked,SU may attain more information about the primary network(making CR more intelligent) and design the subsequent optimization strategy.The key technology is the multiple hypothesis testing as opposed to the traditional binary hypothesis testing.We discuss two situations under whether the channel phase is known or not,and we derive the closed form solutions for decision regions and several performance metrics,from which some interesting phenomenons are observed and the related discussions are presented.Numerical examples are provided to corroborate the proposed studies.     

AC-PDP发光物理过程及影响发光效率、亮度因素的探讨

分析了彩电ＡＣ－ＰＤＰ平面显示结构原理,着重讨论了其物理发光过程,并提出进一步提高ＡＣ－ＰＤＰ发光效率和亮度的途径。