一种基于自耦原理的农网低电压补偿变压器

农村配电距离长,线损大,其导致的线路中端和末端电压不足是目前农村电网的主要难题.设计了一种自耦型农网低电压补偿变压器,该变压器将二次侧串联入主电路,只需要提供该节点的缺失电压即可达到低电压治理的效果,变压器容量小、成本低,可在同一线路多个节点进行配置.各相二次侧分接头由IGBT控制独立,可以治理三相电压不平衡.最后对补偿变压器进行了数字仿真校验以及数字物理混合实验校验,证明了该方法能够保证线路各节点的电能质量,同时与其他低电压治理方法的经济性进行对比分析,验证了补偿变压器具有较高的经济性.     

Characterizing and optimizing TPC-C workloads on large-scale systems using SSD arrays在大规模系统上优化 TPC-C 评测程序

Transaction processing performance council benchmark C (TPC-C) is the de facto standard for evaluating the performance of high-end computers running on-line transaction processing applications. Differing from other standard benchmarks, the transaction processing performance council only defines specifications for the TPC-C benchmark, but does not provide any standard implementation for end-users. Due to the complexity of the TPC-C workload, it is a challenging task to obtain optimal performance for TPC-C evaluation on a large-scale high-end computer. In this paper, we designed and implemented a large-scale TPC-C evaluation system based on the latest TPC-C specification using solid-state drive (SSD) storage devices. By analyzing the characteristics of the TPC-C workload, we propose a series of system-level optimization methods to improve the TPC-C performance. First, we propose an approach based on SmallFile table space to organize the test data in a round-robin method on all of the disk array partitions; this can make full use of the underlying disk arrays. Second, we propose using a NOOP-based disk scheduling algorithm to reduce the utilization rate of processors and improve the average input/output service time. Third, to improve the system translation lookaside buffer hit rate and reduce the processor overhead, we take advantage of the huge page technique to manage a large amount of memory resources. Lastly, we propose a locality-aware interrupt mapping strategy based on the asymmetry characteristic of non-uniform memory access systems to improve the system performance. Using these optimization methods, we performed the TPC-C test on two large-scale high-end computers using SSD arrays. The experimental results show that our methods can effectively improve the TPC-C performance. For example, the performance of the TPC-C test on an Intel Westmere server reached 1.018 million transactions per minute.     

Optical Design of Silica Aerogels for On-Demand Thermal Management

Silica aerogels, a type of porous material featuring extra low density and thermal conductivity, have drawn increasing interest from both academia and industry owing to their excellent thermal insulation performance. However, thermal insulation is always the single consideration when silica aerogels are used for thermal management. In this study, the on-demand thermal management (ODTM) of silica aerogel with either passive thermal insulation, passive heating, or passive cooling in different environments is revealed. The ODTM behavior of silica aerogels can be simply fulfilled through their optical property variations such as solar light transparency and infrared emissivity, which are controllable via the microstructures of the building blocks and surface composition design. Robust solar heating of 25 °C higher than the ambient in the daytime and sub-ambient cooling of 7 °C at night is achieved with the traditional transparent silica aerogel. Interestingly, sub-ambient cooling of 5 °C in the daytime and a warmer state on cold nights is achieved by modifying its solar transmittance and infrared emissivity. This study guides a comprehensive understanding of the thermal management behavior of silica aerogels and leads to ODTM applications of silica aerogels by tailoring their optical and thermal conductivity properties.     

CuI Encapsulated within Single-Walled Carbon Nanotube Networks with High Current Carrying Capacity and Excellent Conductivity

High current carrying capacity and high conductivity are two important indicators for materials used in microscale electronics and inverters. However, it is challenging to obtain high conductivity and high current carrying capacity at the same time since high conductivity requires a weakly bonded system to provide free electrons, while high current carrying capacity requires a strongly bonded system. In this paper, CuI@SWCNT networks by filling the single-walled carbon nanotubes (SWCNTs) with CuI is ingeniously prepared. CuI@SWCNT shows good stability due to the confinement protection of SWCNTs. Through the host-guest hybridization, CuI@SWCNT networks exhibit a current carrying capacity of 2.04 × 10⁷ A cm⁻² and a conductivity of 31.67 kS m⁻¹. Their current carrying capacity and conductivity are significantly improved compared with SWCNT. The Kelvin probe force microscopy measurements show a drop of surface potential energy after SWCNT filled with CuI, indicating that the CuI guest molecules regulate the position of the Fermi level of SWCNTs, increasing carrier concentration, achieving high conductivity and high current carrying capacity. This study offers ideas and solutions for the regulation of high-performance carbon tube networks, which hold great promise for future applications in carbon-based electronic devices.     

Large‐Stroke Electrochemical Carbon Nanotube/Graphene Hybrid Yarn Muscles

Artificial muscles are reported in which reduced graphene oxide (rGO) is trapped in the helical corridors of a carbon nanotube (CNT) yarn. When electrochemically driven in aqueous electrolytes, these coiled CNT/rGO yarn muscles can contract by 8.1%, which is over six times that of the previous results for CNT yarn muscles driven in an inorganic electrolyte (1.3%). They can contract to provide a final stress of over 14 MPa, which is about 40 times that of natural muscles. The hybrid yarn muscle shows a unique catch state, in which 95% of the contraction is retained for 1000 s following charging and subsequent disconnection from the power supply. Hence, they are unlike thermal muscles and natural muscles, which need to consume energy to maintain contraction. Additionally, these muscles can be reversibly cycled while lifting heavy loads.     

SDB:一个面向分布式GIS的空间数据库

SDB是一个面向分布式地理信息系统的空间数据库系统.该系统采用软件组件模型,符合OpenGIS规范,具有互操作性,支持数据共享和功能共享,能够用于GIS软件的集成,支持面向因特网的组件化GIS软件的开发.     

一类柔软物体悬垂模拟中的变形约束

使用质点—弹簧模型来表示一类柔软物体(如织物)的建模方法在实时模拟技术中得到了广泛的应用。根据质点—弹簧模型的特点，在显式尤拉数值积分方法的基础上，创造性地提出了一种速度修正算法来克服建模方法所产生的超弹性行为。理论分析和实验均证明，该修正算法在不增加原有方法计算复杂度的前提下，有效地改善了悬垂结果的视觉准确性和真实性；同时，该修正算法也有效地弥补了显式尤拉算法的不稳定性。两者相结合的积分算法在模拟一类柔软物体悬垂行为的应用中是快速、稳定和准确的高效算法，非常适合应用于三维服装CAD中。     

数字式介质损耗因数tanδ检测仪的设计

介绍了一种利用基波相位分离法实现电气绝缘设备介质损耗因数（tanδ）数字化检测的方法，根据其原理设计了以DS80C320单片机构成的绝缘介质损耗检测仪，中详细描述了其硬件组成和软件设计，给出了该仪器装置测量的实验结果。     

邻基参与与非经典碳正离子

描述了非经典碳正离子和经典碳正离子的区别及邻基参与形成的非经典碳正离子．