Selection of test paths for solder joint intermittent connection faults under DC stimulus

The test path of solder joint intermittent connection faults under direct-current stimulus is examined in this paper. According to the physical structure of the circuit, a network model is established first. A network node is utilised to represent the test node. The path edge refers to the number of intermittent connection faults in the path. Then, the selection criteria of the test path based on the node degree index are proposed and the solder joint intermittent connection faults are covered using fewer test paths. Finally, three circuits are selected to verify the method. To test if the intermittent fault is covered by the test paths, the intermittent fault is simulated by a switch. The results show that the proposed method can detect the solder joint intermittent connection fault using fewer test paths. Additionally, the number of detection steps is greatly reduced without compromising fault coverage.     

Ultranarrow Bandwidth Organic Photodiodes by Exchange Narrowing in Merocyanine H‐ and J‐Aggregate Excitonic Systems

Ultranarrowband organic photodiodes (OPDs) are demonstrated for thin film solid state materials composed of tightly packed dipolar merocyanine dyes. For these dyes the packing arrangement can be controlled by the bulkiness of the donor substituent, leading to either strong H‐ or strong J‐type exciton coupling in the interesting blue (H‐aggregate) and NIR (J‐aggregate) spectral ranges. Both bands are shown to arise from one single exciton band according to fluorescence measurements and are not just a mere consequence of different polymorphs within the same thin film. By fabrication of organic thin‐film transistors, these dyes are demonstrated to exhibit hole transport behavior in spin‐coated thin films. Moreover, when used as organic photodiodes in planar heterojunctions with C₆₀ fullerene, they show wavelength‐selective photocurrents in the solid state with maximum external quantum efficiencies of up to 11% and ultranarrow bandwidths down to 30 nm. Thereby, narrowing the linewidths of optoelectronic functional materials by exciton coupling provides a powerful approach to produce ultranarrowband organic photodiodes.     

2.5Gb/s光纤通信系统的电色散补偿技术研究

介绍了逐渐受到更多关注的高速光纤通信系统的电色散补偿(EDC)技术.我们将研究对象放在了采用啁啾DFB激光器、直接调制方式的2.5Gb/s高速光纤通信系统,通过仿真得到:啁啾系数为2的DFB激光器传输400km后经过8抽头判决反馈均衡器处理可有效地消除色散导致的码间干扰.     

A 5 Gb/s multi-mode transmitter with de-emphasis for PCI Express 2.0/USB 3.0

A versatile transmitter compatible SERDES system was fabricated in 55 nm CMOS technology. The proposed transmitter comprises a low-power and low-area driver with de-emphasis and a 10:1 serializer, meanwhile it supports power management to reduce the unnecessary dissipation and to complete the mode transition among four power modes. Furthermore, the transmitter is compatible with PCI Express 2.0/1.0 and also meets the USB 3.0 standard. The experimental results show this test chip passes PCI Express 2.0/1.0 TX compliance test and USB 3.0 TX compliance test. The chip occupies 0.033 mm² and consumes 33 mA at 5 Gb/s.     

TD—LTE系统Reed—Muller译码的仿真及FPGA实现

主要基于FPGA实现TD—LTE系统中的Reed—Muller译码,包括Reed—Muller译码的介绍、方案的构成、FPGA实现流程、以及实现结果分析。并在Virtex-6芯片上,进行了仿真、综合、板级验证。实现结果表明,该Reed—Muller译码算法应用到TD—LTE射频一致性测试仪表中具有良好的高效性和可靠性。     

A game model for information dissemination in live streaming e-commerce environment

As a new form of social e-commerce, live streaming e-commerce is becoming increasingly popular among Chinese consumers. Live streaming brings huge opportunities, and we can take measures to further expand the dissemination of live streaming information. A live streaming information dissemination game model based on social evolutionary game theory is presented to simulate multiple complex live streaming e-commerce networks. The introduction of incentive mechanism in the model further quantifies the internal relation between rewards and live streaming information dissemination to a certain extent and predicts the ratings of live streaming in networks with different update frequency of social relationships. The simulation results indicate that the reputation environment in social networks, adjusting frequency of relationship, pre-broadcast rewards to post-broadcast rewards ratio all have certain ranges of impact on information dissemination in live streaming e-commerce environment and then affect the live streaming ratings. These findings offer insights into the dissemination of live streaming information in social networks.     

基于信捷PLC对细石混凝土泵电气系统的设计

为了推进细石混凝土泵的国产化,在保证产品性能的前提下,降低其电气系统的生产成本,采用以国产信捷PLC(Programmable Logic Controller)为主的控制元件对细石混凝土泵电气系统进行了设计。在保证细石混凝土泵使用稳定性的同时,降低了其电气系统的制造成本,提高了适用性。所设计电气系统经菏泽永安机械制造有限公司检验使用,实际应用情况良好。     

Performance Evaluation of IEEE 802.15.4 CSMA/CA Scheme Adopting a Modified LIB Model

Since the successful release of the IEEE 802.15.4 standard, a great convenience is offered to applications in low-power and low-rate wireless sensor networks (WSNs) which almost touch upon all aspects in our surrounding circumstances. For time-critical applications, we use a modified Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism called Linear Increase Backoff (LIB) to enhance the performance of packet delay, but not compromise the metrics of energy efficiency and throughput. An accurate and comprehensive Markov model is used to analyze the characteristics of our LIB scheme predicting packet delay, energy consumption and throughput of unsaturated, unacknowledged IEEE 802.15.4 networks in which the unsaturated state is dependent on the traffic condition rather than the depiction by a predetermined length. Simulation results are consistent with the predictions of this model. We also compare the performance of LIB with that of several mechanisms according to the optimal parameters selected from operating point, and find that packet delay is obviously superior to that of other schemes, while energy efficiency and throughput are superior to others for large number of nodes and high traffic arrivals.     

Nitrate Additives Coordinated with Crown Ether Stabilize Lithium Metal Anodes in Carbonate Electrolyte

Lithium metal anodes (LMAs) are promising for next-generation batteries but have poor compatibility with the widely used carbonate-based electrolytes, which is a major reason for their severe dendrite growth and low Coulombic efficiency (CE). A nitrate additive to the electrolyte is an effective solution, but its low solubility in carbonates is a problem that can be solved using a crown ether, as reported. A rubidium nitrate additive coordinated with 18-crown-6 crown ether stabilizes the LMA in a carbonate electrolyte. The coordination promotes the dissolution of NO₃⁻ ions and helps form a dense solid electrolyte interface that is Li₃N-rich which guides uniform Li deposition. In addition, the Rb (18-crown-6)⁺ complexes are adsorbed on the dendrite tips, shielding them from Li deposition on the dendrite tips. A high CE of 97.1% is achieved with a capacity of 1 mAh cm⁻² in a half cell, much higher than when using the additive-free electrolyte (92.2%). Such an additive is very compatible with a nickel-rich ternary cathode at a high voltage, and the assembled full battery with a cathode material loading up to 10 mg cm⁻² shows an average CE of 99.8% over 200 cycles, indicating a potential for practical use.     

分布式光伏发电系统的应用研究

随着新能源的快速发展,分布式光伏发电得到普遍推广应用,在碳达峰和碳中和的政策背景下,光伏发电从以集中式地面电站为主逐步过渡到分布式发电遍地开花的应用阶段,既考验电力系统的承载能力,同时促进新型电力系统网络架构的加速建设,本文通过对分布式光伏发电多种应用形式的研究介绍,结合当前存在的一些问题提出改善建议。