基于信息生命周期的政府信息服务安全保护模型研究

我国政府信息服务正逐渐从简单的信息提供向信息公开、数据开放和与互联网深度整合方向发展,在此发展过程中,如何实现政府信息服务与信息安全的平衡是政府服务信息服务提供者需要面对的问题.基于生命周期理论提出了以政府信息(数据)生命周期为核心,围绕人、地、事、物等要素,开展政府信息服务全生命周期安全运营的政府信息服务安全保护框架...     

Energy payback and life‐cycle CO2 emissions of the BOS in an optimized 3·5 MW PV installation

This study is a life‐cycle analysis of the balance of system (BOS) components of the 3·5 MW_p multi‐crystalline PV installation at Tucson Electric Power's (TEP) Springerville, AZ field PV plant. TEP instituted an innovative PV installation program guided by design optimization and cost minimization. The advanced design of the PV structure incorporated the weight of the PV modules as an element of support design, thereby eliminating the need for concrete foundations. The estimate of the life‐cycle energy requirements embodied in the BOS is 542 MJ/m², a 71% reduction from those of an older central plant; the corresponding life‐cycle greenhouse gas emissions are 29 kg CO₂ eq./m². From field measurements, the energy payback time (EPT) of the BOS is 0·21 years for the actual location of this plant, and 0·37 years for average US insolation/temperature conditions. This is a great improvement from the EPT of about 1·3 years, estimated for an older central plant. The total cost of the balance of system components was $940 US per kW_p of installed PV, another milestone in improvement. These results were verified with data from different databases and further tested with sensitivity‐ and data‐uncertainty analyses. Copyright © 2005 John Wiley & Sons, Ltd.     

Modeling Energy Recovery Using Thermoelectric Conversion Integrated with an Organic Rankine Bottoming Cycle

Engine and industrial waste heat are sources of high-grade thermal energy that can potentially be utilized. This paper describes a model system that employs thermoelectric conversion as a topping cycle integrated with an organic Rankine bottoming cycle. The model has many parameters that define combined system quantities such as overall output power and conversion efficiency. The model can identify the optimal performance points for both the thermoelectric and organic Rankine bottoming cycle. Key analysis results are presented showing the impact of critical design parameters on power output and system performance.     

低占空比、低碰撞的异步无线传感器网络MAC协议

提高信道监听质量是降低能量消耗和提高通信效率的有效方法。提出了一种低占空比、低碰撞的PB-MAC(predict-base MAC)协议。通过发送节点精确预测接收节点的唤醒时间,降低占空比;采用基于预测的重建连接机制和数据重传机制,有效地避免碰撞和实现高效重传。OMNet++仿真实验结果表明：在50节点随机网络中,PB-MAC的平均占空比、发送消息耗能和平均碰撞次数分别比RI-MAC少68.60%、24.75%、68.05%,比X-MAC少64.39%、64.05%、70.54%。同时,在网格网络中PB-MAC的性能也优于RI-MAC和X-MAC。     

检察院全国使用统一的检察业务系统的风险管理研究

检察院内网是检察专线搭建的独立的四级检察院互联的内部网络,必须与其它网络物理隔离。检察内网相对互联网相对安全,但网络本身存在脆弱性与外来的不稳定因素存在风险,所以需要对全国使用统一的检察业务系统作一个风险管理研究,这里介绍了对应风险管理的基本架构与概念,重点探讨风险管理的工作内容,浅谈信息安全风险评估实践的内容与相关的国家政策。     

基于RCM 的导弹装备最佳预防性维修周期决策

针对目前确定预防性维修周期时存在不确定性的问题,建立了基于RCM的导弹装备维修周期决策模型。分别以总费用最小和可用度最大为目标建立导弹装备维修周期决策模型,采用蒙特卡罗仿真进行模型求解,采用模糊决策方法确定多目标综合最佳预防性维修周期,并以某型导弹装备密封圈为例,验证方法的有效性。实践分析结果表明:该方法综合权衡了费用和可用度因素,能较好地解决可用度低下且维修费用居高不下的问题,有一定应用和参考价值。     

实施成本分析闭环管理的紧迫性和必要性探讨

目前,各地广电网络公司比较注重工程建设过程中的成本控制,实行了如设计外包、工地现场管理系统、单项工程专业审计等举措,取得了较好效果;但对于项目总体成本分析及分析后改进措施的落实则较弱,未按照PDCA机制要求形成闭环,结合如皋2020上半年工程造价中施工费占比明显上升(58%)的实际情况,浅析实施成本分析闭环管理的紧迫性和必要性。     

Brine Refrigerants for Low-cost,Safe Aqueous Supercapacitors with Ultra-long Stable Operation at Low Temperatures

Traditional aqueous energy storage devices are difficult to operate at low temperatures owing to the poor ionic conductivity and sluggish interfacial dynamics in frozen electrolytes. Herein, the low-cost brine refrigerants for food freezing and preservation as electrolytes, and unexpectedly realize high ionic conductivity and stable operation of an aqueous storage device at low temperatures are demonstrated. A CaCl₂ brine refrigerant electrolyte (BRE) with a low freezing point −55 °C and high ionic conductivity (10.1 mS cm⁻¹ at −50 °C) is developed for supercapacitors (SCs), which retains 80% of the room temperature capacity at −50 °C and exhibits ultra-long cycle life with excellent capacity retention of 92% over 98,500 cycles, outperforming the other SCs which can be operated below −40 °C in literature. Moreover, the SCs with MgCl₂ and NaCl BREs can also be operated successfully with excellent cycle stability and high-capacity retention at low temperatures of −30 and −20 °C, respectively. Fundamental correlation between various cations and their effect on the freezing point reduction of aqueous electrolytes is revealed via Raman investigation and molecular dynamics simulations. This study provides a rational design strategy for green, inexpensive, and safe low-temperature aqueous electrolytes for energy storage devices.     

Vienna整流器单周控制技术研究

通过分析三相三开关三电平(Vienna)整流器的工作原理,研究了该整流器的单周控制策略,并采用电压外环和电流内环的双闭环控制,实现了Vienna整流器的可靠稳定、低谐波畸变特性。基于Matlab仿真平台,搭建了Vienna整流器的仿真模型,仿真结果表明,基于单周控制方法的8 kW三相PFC整流器,控制结构简单,系统可靠稳定,谐波畸变率＜3%,功率因数可达99%。     

一种用于FPGA的快速锁定全数字延时锁定环的设计实现

本文提出了一种用于FPGA中DDR SDRAM控制器的接口快速锁定的全数字延时锁定环。该电路对数据选择脉冲(DQS)实现90度的相位偏移。为了实现延时锁定环的快速锁定,同时解决了错误锁定的问题,本文提出了一种新颖的数字时间转换器的结构。在延时环路中设计了占空比纠正电路,实现50％的占空比输出。该延时锁定环电路采用0.13μm标准CMOS工艺设计制作。测试结果表明,工作频率范围为75MHz～350MHz,数字控制延时链(DCDL)的调节精度为15ps,并且电路的闭环特性能跟踪电压、温度等环境的变化。