太阳能电池与反射阵天线的一体化集成设计

提出了一种与太阳能电池板集成的反射阵天线。用太阳能片底部金属层作为反射阵单元的辐射贴片,使得照射在太阳能电池上的光照不受天线遮挡,实现了最大化的光电转化效率。反射阵单元尺寸为0.4λ₀×0.4λ₀。单元相移范围达到543°。用该单元组成了单元数为15×15的反射阵列天线,阵面口径大小为690 mm×690 mm(6λ₀×6λ₀)。采用标准增益喇叭天线作为反射阵馈源。仿真结果表明,在2.6 GHz反射阵的增益达到22.5 dBi,口径效率为39.5%。     

现代城市规划中的"街"与"道"

近年来,随着社会经济的快速发展,大、中城市普遍出现了"交通日益紧张,路网效能低下"的现象.与此同时,伴随着机动车的增长,传统城市的街道生活空间正在逐步消失.不可否认,道路功能混杂、路网级配不合理是造成这种现象的直接原因之一.     

大跨度马鞍型钢结构支撑卸载施工技术

对大跨度马鞍型钢结构支撑卸载施工从卸载原则、卸载操作流程、卸载操作要点及卸载质量控制等方面进行了深入研究,总结出大跨度马鞍型钢结构支撑卸载施工技术,可对类似工程施工提供参考.     

改进型二维位置敏感探测器示值误差的标定

分析了改进表面分流型二维PSD传感器的工作原理及信号调理电路,针对PSD传感器示值误差较大的缺点,设计了利用万能工具显微镜的实验标定系统,运用误差理论对传感器位置测试数据进行了标定修正。试验结果表明,PSD传感器A区的示值误差可减小到±0·02mm内。     

从疏到密,从密返疏——宁波老城街道网密度的演变

随着中国古代城市规划模式由"坊市制"转向更适合于商品经济发展的"坊巷制",宁波老城街道网密度经历了从疏到密的转变;而近现代由于交通方式的变革、土地所有制的变化和建筑生产方式的转变,宁波老城街道网密度又经历了从密返疏的转变.这一从疏到密、从密返疏的演变过程,不仅反映了宁波"城与市"相结合的城市特色,还从一个侧面反映出了中国传统城市格局的演变过程.     

皮带输送机传动系统故障分析

1 存在的问题 皮带输送机由于结构简单,维护方便,可输送物料种类繁多,在企业生产中得到广泛应用.近日我公司一条石膏破碎输送皮带在例行设备周期监测时,发现电机与减速机振动值异常.以联轴器不同心故障为主,从振动值及频谱图,联轴器对中,着重分析设备故障,设备测点布置见图1,设备参数见表1,振动检测仪器对设备采集数据见表2.     

IEC 60950-1:2005和GB4943-2001的主要差异

在日常生活中,会接触到各式各样的Ⅰ类信息设备,如计算机、复印机、银行自助终端和交换机等.     

Effect of pore characteristics of fine lignite on particle density in separation medium

Effect of porosity on particle density was analyzed, which can be a potential factor of low efficiency. The porosity of particle with different densities was detected by surface area analyzer. In addition, Three-dimensional X-ray micro-imaging system (3D-XRM) was used to analyze the spatial distribution of internal pores. Results show that mesoporous and microporosity content increase with the increase of particle density. Three-dimensional distribution of pores shows that the pores are very rich and show a good connection. The density model including porosity and medium density was established, which shows the effect of medium filling on the change of particle density.     

Study of tritium transport characteristics in a transportable fluoride‐salt‐cooled high‐temperature reactor

Tritium management is one of the most critical issues that limit the development of fluoride‐salt‐cooled high‐temperature reactor (FHR); therefore, it is important to figure out the tritium transport characteristics in FHRs. In this paper, 3 works concerning about tritium in FHR are conducted: first, the tritium transport characteristics in the primary loop of FHRs are introduced, including tritium production and speciation, the absorption and desorption by graphite, dissolution and diffusion in molten salt, and permeation through structural materials. Second, the physical and mathematical models are established for tritium transport characteristic analysis in a transportable FHR (TFHR). The tritium transport characteristic analysis code (TAPAS) for TFHR is developed and benchmarked. The results prove the fidelity and accuracy of TAPAS. Finally, the tritium transport characteristics in the TFHR are analyzed systematically by TAPAS. Three conclusions are obtained: (1) tritium in the primary coolant loop is mainly in the form of T₂; (2) when TFHR operates at steady state, the permeation rate of T₂ can be regarded as a constant (9.03 × 10⁹ Bq ? EFPD^?1 ); and (3) ⁷Li enrichment and redox potential of molten salt have great influence on the tritium distribution. This work might provide contribution to the tritium control in FHRs.