摘要：This paper describes a new interleaver construction technique for turbo code. The technique searches as much as possible pseudo-random interleaving patterns under a certain condition using genetic algorithms(GAs). The new interleavers have the superiority of the S-random interleavers and this interleaver construction technique can reduce the time taken to generate pseudo-random interleaving patterns under a certain condition. The results obtained indicate that the new interleavers yield an equal to or better performance than the S-random interleavers. Compared to the S-random interleaver, this design requires a lower level of computational complexity. Key words interleaver - Turbo codes - genetic algorithm CLC number TN 911. 22 Foundation item: Supported by the National Natural Science Foundation of China (60372057) and the Key Open Laboratory on Information Science and Engineering of Railway Transportation Ministry of Beijing Jiaotong University of China (KLISAE-0103)Biography: Tan Ying (1963-), female, Associate professor, Ph. D, research direction: error control coding, analysis and design of wireless communication system.

摘要：The paper presents a wideband high frequency (HF) channel simulator. The simulation consists of a software simulation of a direct-sequence spread-spectrum (DSSS) HF system with RAKE receiver. The validity of the HF channel simulator is demonstrated by the analysis of the scattering function and example results of the simulator. The performance of DS system under HF channel and noise are also presented. The simulation results and theoretical analysis show that a straightforward DS system may properly mitigate the intersymbol interference (ISI) distortion of the HF channel while perform badly under the HF noise and interference.

摘要：目的构建腹壁-盲肠损伤粘连模型并探究改性木葡聚糖(mXG)温敏水凝胶对腹壁-盲肠损伤粘连的防治效果。方法选用SD大鼠构建腹壁-盲肠损伤粘连模型,随机分为空白对照组(Control)、商业化壳聚糖膜对照组(Film)和mXG温敏凝胶组(Hydrogel),每组16只。Hydrogel组,将1 mL 4%(m/V)mXG溶液涂抹至腹壁和盲肠的创面,待凝胶形成(3 min)后关腹;Film组,关腹前将2 cm×3 cm大小的壳聚糖防粘连膜覆盖于腹壁创面;Control组,关腹前将1 mL生理盐水注射于腹壁和盲肠的创面。术后7 d和14 d,开腹检查腹壁与盲肠的粘连情况,采用双盲设计进行粘连评分。取同一部位粘连组织或创面组织,进行HE、Masson和Van Gieson染色后,进行防粘连效果组织学评价,免疫组织化学染色检测转化生长因子-β1(TGF-β1)和结缔组织生长因子(CTGF)的表达情况。另取12只SD大鼠予以造模和mXG温敏水凝胶干预,术后第1周和6周取心、肝、脾、肺、肾等主要脏器使用HE染色进行组织学检查,进行体内毒性评价。结果动物模型大体观察发现,Hydrogel组的大鼠基本未发生粘连,Film组发生轻度粘连,Control组发生了严重的粘连,差异有统计学意义(P<0.05)。组织学镜下观察发现,7 d时Hydrogel组创面恢复良好,未看到变异的组织,有一定程度的炎性细胞浸润;14 d时创面组织中的炎性细胞明显减少,新生间皮层下仅含有少量胶原纤维的愈合组织;而7 d、14 d,其余两组均出现不同程度粘连的病理表现。免疫组织化学染色发现,Hydrogel组TGF-β1和CTGF的阳性表达一致且较其它两组弱,差异有统计学意义(P<0.05)。体内毒性检测发现,使用mXG凝胶的动物在不同时间点各脏器的结构均没有出现明显变化。结论 mXG温敏水凝胶能够在粘连形成的关键时期起到良好的物理隔离作用,有效预防盲肠-腹壁粘连的发生。

摘要：从不同正火温度对高压锅炉用12Cr2MoWVTiB钢管高温性能影响的研究结果表明．生产过程中该钢的正火温度不低于1020℃，才能满足锅炉设计对该钢持久强度性能的要求。

摘要：基于NOAA WOA 2018数据集数据,用Nihous方法评估2005—2017年南海、西沙群岛海域以及1955—2017年永兴岛海域温差能资源储量,分析温差能资源的时空变化特点。为符合永兴岛温差能电站选址要求,对永兴岛周边海域温差能资源分布和水深条件进行更具体的分析,选出8个温差能发电潜在站址,再结合温差能净功率、离岸距离及水深等因素,找出相对更适宜的4个站址,并对这些站址温差能发电的净功率年际变化加以分析。

摘要：为研究开级配橡胶沥青混合料在排水降噪路面中的应用,解决公路工程中路面的抗滑、排水、降噪问题,论文对开级配橡胶沥青混合料的配合比优化设计进行研究,包括橡胶沥青、集料的选用,通过试验确定最大沥青用量和最小沥青用量,并得出结论:在最佳油石比为8.3%时,沥青混合料的马歇尔稳定度最大。

摘要：现代高参数大容量火电锅炉,水冷壁的高温区都采用内螺纹管以防止水与管壁之间形成蒸汽膜,降低传热效率.内螺纹管的螺纹头数根据设计需要有8、12和14头不等.内螺纹的旋转方向可分单向和正反交叉两种,形式很多,各国尚无统一标准.国产1050 t/h锅炉(配300 MW机组)每台内螺纹管用量200～250 t;2045 t/h锅炉(配600 MW机组)每台内螺纹管用量约300 t.全国按年产12000 MW火电设备计算,需内螺纹管6000 t以上.

摘要：Electrochemical CO_(2)reduction reaction(CO_(2)RR)driven by sustainable energy has emerged as an attractive route to achieve the target of carbon *** is one of the most economically viable products,and electrocatalytic CO_(2)RR to formate is a promising ***-pressure H-cell electrolyzer is easy to operate and allows high CO_(2)solubility for realizing high current density,but the design of highly efficient catalysts for working under high CO_(2)pressures remains ***-based catalysts exhibit high formate selectivity,but suffer from limited ***,we report a high-performance catalyst,which is derived from BiPO_(4)nanopolyhedrons during electrocatalytic CO_(2)RR to formate in neutral solution under high CO_(2)pressures.A high partial current density of formate(534 mA cm^(−2))and formate formation rate(9.9 mmol h^(−1) cm^(−2))with a formate Faradaic efficiency of 90%have been achieved over BiPO_(4)-derived catalyst at an applied potential of−0.81 V *** under 3.0 MPa CO_(2)*** discover that BiPO_(4)nanopolyhedrons evolve into metallic Bi nanosheets with rich grain boundaries in electrocatalytic CO_(2)RR under high CO_(2)pressures,and the grain boundaries of the BiPO_(4)-derived catalyst play a vital role in promoting electrocatalytic CO_(2)RR to *** theoretical studies reveal that the charge redistribution occurs at the grain boundaries of Bi surface,and this promotes CO_(2)activation and increases HCOO^(*)intermediate stability,thus making the pathway for CO_(2)RR to formate more selective and *** work not only demonstrates a highly efficient catalyst for CO_(2)RR to formate but also discovers a unique feature of catalyst evolution under high CO_(2)pressures.

摘要：医学是理论与实践并重的应用学科，实验教学是医学教育的重要组成部分。多年来，我国实验教学附属于理论教学，存在重理论、轻实践的现象。形态学实验教学作为医学实验的组成部分，一直以验证性实验为主。