坝内式水电厂GPS信号接收的方案设计与实现

电力系统是一个规模巨大的互联系统 ,获取系统关键点及主要设备的运行状态信息 ,必须依赖于统一的高精度的时间基准 ,GPS的出现使得全网的统一时钟变为现实。对于坝内式水电厂GPS信号的接收 ,当不能满足GPS卫星天线在 2 0m以内且天线上方 15°角锥内无结构遮挡的要求时 ,必须采用一定的措施才能满足电网状态监测的需要。本文介绍的设计方案可以有效解决这一问题。该方案的实现有利于水电厂基于GPS的监控、保护等单元的时钟统一 ,进而对分析事故起因有重要的意义     

Surface stress‐induced membrane biosensor based on double‐layer stable gold nanostructures for E. coli detection

The surface stress‐based biosensor has been applied in fast and sensitive identification of Escherichia coli (E. coli)with significance for public health, food, and water safety. However, the stable sensitive element of flexible biosensor based on surface stress is still crucial and challengeable. Here, the authors reported surface stress‐induced biosensors based on double‐layer stable gold nanostructures (D‐AuNS‐SSMB) for E. coli O157:H7 detection. Bacterial detection demonstrates the high stability of the biosensor. The resistance change of biosensor is linear to the logarithmic value of the E. coli O157:H7 concentrations ranging from 10³  to 10⁷  CFU/mL with a limit of detection (LOD) of 43 CFU/mL. The captured signals of D‐AuNS‐SSMB comes from surface stress generated by antigen–antibody binding. In addition, the biosensor exhibits good stability, reproducibility and specificity in detection of E. coli O157:H7 as well. This study provides a new preparation method of stable sensitive element for the E. coli detection.Inspec keywords: microorganisms, biosensors, gold, membranes, stress measurement, nanostructured materials, nanosensorsOther keywords: double‐layer stable gold nanostructures, D‐AuNS‐SSMB, bacterial detection, surface stress‐induced membrane biosensor, escherichia coli detection, water safety, stability, E. coli O157:H7 concentration detection, antigen–antibody binding, Au     

野生酵母及其对啤酒生产的影响

讨论了啤酒生产常见野生酵母的种类及其对啤酒生产和质量的影响，并提出了野生酵母的检验和消除方法。     

Analysis of an accelerated trip scheme for faults in the secondzone of protection of a transmission line

An analysis of a scheme of accelerated trips for faults in the second zone of a transmission line distance protection system is given. By the use of the two-port network theory, variations of the sequence currents and voltages are analyzed when the fault occurs on the protected line followed by a trip of the circuit breaker on the other side. The analysis is supported by tests performed on a laboratory model of a power system. The new scheme can improve sensitivity and avoid improper operation. Thus, it may be possible to use this scheme instead of pilot protection and alleviate any problems caused by the nonavailability of a sufficient number of communication channels for remote control and relaying     

井架可靠性设计中抗力的确定

在大量调研统计的基础上，运用结构可靠性理论，求得了ＪＪ２５０／４２－Ｋ型井架抗力的概率分布类型及抗力系数。井架构件的抗力服从于对数正态分布，抗力均值ｍＲ＝ｋＲＲｋ。井架常用钢材为１６Ｍｎ和Ａ３，其抗力系数ｋＲ和Ｒｋ可由资料查得。对１６Ｍｎ和Ａ３以外的钢材，根据概率统计法，对影响抗力的３个主要因素──材料强度、截面几何特性和计算模式，分别确定各自的均值与标准差，然后求得抗力系数和抗力变异系数。     

"三加一"集约管理模式在新集的实践与思考

国投新集公司把"三加一"集约管理模式作为构筑跨世纪管理战略的重要组成部分和保持、促进企业高效发展的体制保证."三加一"即成本、质量、安全和人的行为管理.国投新集公司围绕管理提升的目标,采取"三加一"集约控制模式,着力树立安全效益观念,加强隐性成本控制,推行全面质量管理,以管理层次的提升来保证企业管理战略的实施,为公司形成新的管理体制创造了条件.本文试就"三加一"集约管理模式进行简单的论述.     

轻型钢结构房屋设计的几点建议

轻钢结构已被广泛使用 ,但是在设计时有些问题还有待研究 ,为此 ,介绍设计工作中的几点体会 ,并提出一些设计建议     

牛血清蛋白在亲水硅片表面吸附的原子力显微成像

本文用原子力显微术（AFM）研究了牛血清白蛋白（BSA）在亲水硅片表面的吸附，硅片表面经亲水处理后，将牛血清蛋白（BSA）吸附在表面，采用轻敲模式，可获得清晰的AFM图像，牛血清蛋白（BSA）的AFM图像表明：BSA在亲水硅片表面是单分子，水平吸附在硅片表面，且吸颗粒状；1mg/ml的BSA在吸附30min后为饱和吸附。BSA到达硅表面后，蛋白中可移动的带正电荷的基团可以趋向亲水表面，使BSA与硅表面的静电相互作用由斥力变为吸引力，BSA可以稳定地吸附在亲水硅片表面。     

华京大厦改造

北京城市规模的扩展表现为以老城区为中心向周边辐射，而紫禁城作为大致保留着明代北京城规划基本格局的老城区的核心，已经成为北京城市核心的核心。华京大厦就位于明皇城保护区内，东华门在街南侧，东临南池子大街，西毗南河沿，距东华门仅有数百米之遥，沿街槐树茂密成林，北京传统四合院隐显其后，地理位置非常特殊，是一个极具东方文化色彩的街道环境。