On the Capacity of Cluster-Based Cooperative MIMO Cellular System with Universal or Fractional Frequency Reuse

The information-theoretic capacity for the cluster-based multicell cooperative processing (MCP) network with inter-cluster interference is investigated in this paper. An upper bound for the ergodic capacity is derived by the QR decomposition of the channel matrix, which is concisely expressed and close to the results from numerical simulations. Capacity results for the universal frequency reuse (UFR) network show that the cluster-based MCP system has great advantages over the non-cooperated system, and the capacity gain depends mainly on the size of the cooperative cluster, the radius of the cell and the path loss exponent (PLE). However, the cluster-based UFR system is still interference limited, whose capacity declines sharply due to the inter-cluster interference. Therefore, a cluster-based fractional frequency reuse (FFR) network is proposed to improve the system capacity, simulation results show that the cluster-based FFR system can outperform the UFR system, especially for the cases of small radius of cell or small PLE.     

无熟料水泥混凝土耐酸及耐海水性能研究

无熟料水泥混凝土是利用水淬高炉矿渣和激发剂在常温下经配料、研磨而成的新型水泥来配制的混凝土,其耐酸及耐海水性能不但取决于水淬高炉矿渣的碱度、化学成分和玻璃化率,而且还取决于激发剂的种类和数量.基于此,以废石膏和石灰作为激发剂配制无熟料水泥混凝土(简称NSC)后,进行了耐酸性能和耐海水性能的实验分析.结果表明,其耐酸、耐海水性能远优于普通水泥混凝土.     

Delayed neuropathy and inhibition of soluble neuropathy target esterase following the administration of organophosphorus compounds to hens

BACKGROUND: Disulfide exchange reactions are catalyzed by thiol/disulfide oxidoreductases. These enzymes possess a thioredoxin fold and contain a catalytic disulfide with the sequence Cys-X-X-Cys at the N terminus of an alpha helix. Despite these similarities, the various members differ strongly in their redox potentials (-122 mV to -270 mV). Using the strong oxidant DsbA from Escherichia coli as a model system, we investigated whether the redox properties of these enzymes can be modulated rationally by exchange of the X-X dipeptide. RESULTS: The X-X dipeptide of DsbA (Cys30-Pro31-His32-Cys33) was exchanged by the dipeptides of eukaryotic protein disulfide isomerase (PDI; Gly-His), glutaredoxin (Pro-Tyr), and thioredoxin (Gly-Pro) from E. coli. All variants were less oxidizing than wild-type DsbA and their redox potentials were in the order of the related natural enzymes (DsbA > PDI > glutaredoxin > thioredoxin). The equilibrium constant between glutathione and the thioredoxin-like variant increased 1200-fold compared with wild-type DsbA. The variants also showed a strong increase in the pKa of the nucleophilic cysteine (Cys30). As for glutaredoxin and thioredoxin, the catalytic disulfide stabilized the corresponding variants while destabilizing wild-type DsbA and the PDI-like variant. CONCLUSIONS: The X-X dipeptide in the active site of thiol/disulfide oxidoreductases appears to be the main determinant of the redox properties of these enzymes. This empirical finding should be very useful for the design of new thiol/disulfide oxidoreductases with altered redox potentials and for studying the function of these enzymes in vivo.     

中国人眼对物体色的视觉特性研究

本文对人眼对物体各种颜色视觉的反映进行了研究，并得出了具体数据。     

Power-efficient grating-based scanning optical delay line: time-domain configuration

A power-efficient, grating-based, time-domain rapid scanning optical delay line (TD-RSOD) suitable for optical coherence tomography (OCT) is presented. The 6 dB power efficiency of this TD-RSOD over conventional double-pass Fourier-domain RSOD (FD-RSOD) provides approximately 4 dB SNR advantage in a typical balanced-detection OCT. The scanning performance of TD-RSOD is comparable to that of FD-RSOD.     

一种应用于电力系统的锁相环

随着电力系统的快速发展,电力系统信号分析越来越重要。本文结合电能质量检测、电力变换以及电力系统保护等方面的实际需求,设计分析了一种改进型锁相环(IPLL)。文中利用控制理论详细分析了IPLL的数学模型,基于Matlab/Simulink对IPLL的功能进行了仿真。上述分析表明,该结构可以满足提取电网信号的相位、频率、幅值和基波等信息的需求。与电力系统中普遍应用的锁相环相比,减少了??变换和dq变换等环节,增加了跟踪信号幅值的功能。为电力系统的信号分析提供了一种新思路。     

电力通信网运行方式管理通用图元库

图元是组成图形的基本元素,图形化信息的显示、用户的操作大多通过图元完成.为实现电力通信网运行方式图的信息化、标准化绘制,图形化、智能化管理,文章基于面向对象的思想,采用ActionScript语言建立通用图元库.阐述了图元基类和各级子类的层次结构,给出了图元类中属性的设计方法及操作的具体实现,并将图元信息存入关系数据库,实现了标准化、开放式的运行方式图元库,为图形管理平台提供了易用、便于扩展的数据接口.     

Design and Performance of an Ultra-Narrowband Superconducting Filter at UHF Band

A stepped impedance spiral resonator suitable for high-temperature superconducting (HTS) filter with bandwidth narrower than 0.5% is presented. An eight-pole demonstration HTS filter is developed with a central frequency of 650 MHz and a bandwidth of 0.3%. The measurements show that the insertion loss is less than 0.3 dB, and the return loss is better than 16 dB. The filter has out-of-band rejections of 65 dB at 2 MHz below the passband and 80 dB at 2 MHz above the passband, respectively.     

ZSM-5/MgO质量比对复合催化剂物化性质及合成甲硫醇反应的影响

采用介孔碱性MgO对微孔酸性ZSM-5分子筛进行复合改性,利用液相沉淀包覆技术制备了ZSM-5/MgO复合催化剂,研究了ZSM-5与MgO质量比对复合催化剂物化性质和合成甲硫醇催化性能的影响。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、比表面积及孔隙分析仪(BET)和化学吸附分析仪(CO₂/NH₃-TPD)等手段对不同复合催化剂的晶相组成、微观形貌、孔结构及表面酸碱性进行分析表征。结果表明：ZSM-5/MgO质量比对ZSM-5/MgO复合催化剂的物化性质和催化性能影响较大。过高或过低ZSM-5/MgO质量比制得复合催化剂中MgO结晶度都有所降低,且未形成包覆相结构;ZSM-5/MgO质量比为1/3时制得复合催化剂形成了均匀包覆相结构和微 介孔结构(总比表面积为162 m²/g,总孔体积0.46 cm³/g),同时具有酸碱特性;在反应压力1.0 MPa、反应温度370  ℃、H2S/CH₃OH摩尔比2/1、N₂流速80 mL/min、H₂S流速4.9 mL/min反应条件下合成甲硫醇,复合催化剂表现出优越的催化性能、稳定性及寿命,CH₃OH转化率、CH₃SH选择性和CH₃SH收率分别达到90.48%、90.04%和81.47%,催化剂寿命达到18 h。与单一ZSM-5分子筛相比,复合催化剂寿命延长了7 h,CH₃SH收率提高了13.97百分点。