装卡偏心状态下渐开线齿廓的测量

为降低装卡偏心误差对渐开线齿廓测量的影响,提出了一种装卡偏心状态下渐开线齿廓的测量方法.研究装卡偏心对渐开线齿廓测量与评定的影响,分析装卡偏心误差的成因,提出一种装卡偏心参数计算方法,建立了装卡偏心误差补偿模型.实验结果表明,应用该模型可将偏心量在3/4测头量程内的测量结果补偿到无装卡偏心测量状态,实现装卡偏心状态下渐开线齿廓的精确测量,并且节约齿轮装卡时间.该方法获得的偏心参数也可应用于装卡偏心状态下齿距和螺旋线的测量轨迹调整.     

Improvement of sediment microbial fuel cell performances by design and application of power management systems

One of the ways to generate clean and non-destructive energy is to use the energy stored in the biomass resources by the microbial fuel cells (MFCs). Sediment Microbial Fuel Cells (SMFCs) are a special type of MFCs that use organic materials in aquifers sediment to generate electricity. In this research, the effects of an increase in the electrode surface are investigated. The results showed that the increase in cathode electrode surface had better efficiency than the multi-cathode mode (maximum power generated for a 3-cathode electrode (27 cm³) and 1-cathode electrode (27 cm³) was 526 mW/cm² and 800 mW/cm², respectively. Another parameter affecting the performance of these systems is temperature. In the next step, the power generation rate was measured in different step currents and at different sample times. In the final stage, a power management system (PMS) was designed to optimally utilize the output energy of the improved SMFC, leading to an increase in the output voltage to 3.3 V.     

Adaptive sampling rate control for networked systems based on statistical characteristics of packet disordering

This paper investigates an adaptive sampling rate control scheme for networked control systems (NCSs) subject to packet disordering. The main objectives of the proposed scheme are (a) to avoid heavy packet disordering existing in communication networks and (b) to stabilize NCSs with packet disordering, transmission delay and packet loss. First, a novel sampling rate control algorithm based on statistical characteristics of disordering entropy is proposed; secondly, an augmented closed-loop NCS that consists of a plant, a sampler and a state-feedback controller is transformed into an uncertain and stochastic system, which facilitates the controller design. Then, a sufficient condition for stochastic stability in terms of Linear Matrix Inequalities (LMIs) is given. Moreover, an adaptive tracking controller is designed such that the sampling period tracks a desired sampling period, which represents a significant contribution. Finally, experimental results are given to illustrate the effectiveness and advantages of the proposed scheme.     

单交叉口多目标联合优化的信号配时研究

传统的交叉口信号配时大多只从提高车辆的通行效率这一角度出发,未考虑交叉口处的行人因素以及车辆尾气排放, 容易造成交通事故,加剧环境污染。 从车辆和行人的交通效益以及环保角度出发,在改进的 Webster 延误模型基础上提出了以 车辆延误、行人延误、停车率、通行能力、尾气排放为优化指标的多目标函数,利用改进的粒子群优化算法(PSO)对所建立的多 目标函数求出最佳信号周期;再利用流量比计算公式求出各个相位的红绿灯时间。 使用这种配时方案,在交通流量高峰期,可 以使车辆的延误降低 18. 7%,停车率降低 15. 9%,行人延误降低 17. 8%,尾气排放降低 38%;在交通流量低峰期时,可以使车辆 的延误降低 11. 6%,停车率降低 6. 9%,通行能力提高 8%,行人延误降低 28. 6%,尾气排放降低 5. 6%。 使用这种配时方案在一 定程度上可以提高道路通行能力、减少交通事故、减少尾气排放、降低道路拥堵。     

Ge基二维三角晶格光子晶体的光子带隙

导出了二维三角晶格光子晶体的填充系数与正多边形散射子外接圆半径的普适关系,并利用平面波展开法计算了Ge基二维三角晶格光子晶体的光子带隙.计算表明:Ge圆柱置于空气背景中时,可产生TM、TE带隙,TM带隙占优势;随着Ge填充系数的增大,光子带隙的宽度先增大后减小,其中心频率由高频向低频移动;TM模第一带隙宽度在半径为0.14a处达峰值.空气圆柱置于Ge背景中时,可产生TM、TE及完全带隙,TE带隙占优势;随着空气填充系数的增大,光子带隙的宽度先增大后减小,其中心频率由低频向高频移动;TE模第一带隙宽度和最大完全带隙宽度分别在半径为0.46a和0.49a处达峰值.     

基于单片机与PC机的温度监测系统设计

设计了基于单片机和PC机的温度监测系统,温度传感器采用DS18B20。下位机采用AT89S52单片机,可以显示温度和超限报警。PC机作为上位机设定上下限报警温度,接收单片机的温度数据,处理后实时显示温度和绘制温度曲线,还实现了超限报警和保存数据功能。上位机利用Matlab强大的数值计算、图形显示和串口操作功能,具有友好人机交互界面,实现了温度动态监测。     

The catalytic performance enhancement of Ni2P electrocatalysts for hydrogen evolution reaction by carbon-based substrates

Combination of catalytic active components with substrates is deemed to be a promising approach to pursue high active and stable catalysts. Wherein, carbon-based materials as a kind of frequently-used substrates are well developed, and thus the different effects of them on catalytic active components deserve investigating and contrasting. In this work, well dispersive and ultrafine Ni₂P nanoparticles supported on N-doped reduced graphene oxide (N-RGO) were synthesized through a facial hydrothermal process and subsequent phosphorization. The prepared Ni₂P/N-RGO demonstrates a superior electrocatalytic activity towards hydrogen evolution reaction (HER) in 0.5 M H₂SO₄ solution with a low onset overpotential (80 mV) and small Tafel slope (93.1 mV dec⁻¹). Additionally, as compared with other representative carbon materials (carbon black (C) and carbon nanotubes (CNTs)) in the perspective of specific surface area (SSA), conductivity and electronic interaction in particular, N-RGO demonstrates a preeminent promotional effect as a substrate of Ni₂P.     

Mechanism of upconversion emission enhancement in Y_3Al_5O_（12）：Er~（3＋）/Li~＋ powders

Er3+ and Li+ codoped Y3Al5O12(YAG) powders were prepared for a systematic investigation of their upconversion emissions.X-ray diffraction(XRD),upconversion emission spectra,pump power dependence,FT-IR spectra and decay time were studied to characterize the samples.With Li+ doping,the upconversion emission intensity of Er3+ doped YAG powders was obviously enhanced,accompanied with an increase in the ratio of green to red intensity.The enhancement of emission intensity could be attributed to two mechanisms:on...     

Increase ionic conductivity of a Zn2+/F− synergy Na3Zr2Si2PO12 solid electrolyte for sodium metal batteries

Na₃Zr₂Si₂PO₁₂ (NZSP) solid-state electrolyte is considered one of the most promising solid-state electrolyte because of their excellent electrochemical and thermal stability. Even though, the low conductivity of NZSP solid-state electrolytes hinders practical application. Therefore, an anions/cations co-assisting strategy is proposed by introducing the Zn²⁺ and F⁻. The influence of adding different amounts of Zn²⁺ and F⁻ on the Na⁺ conductivity of NZSP was investigated computationally and experimentally. The Zn²⁺/F⁻ co-assisting (Na_3.3Zr_1.85Zn_0.15Si₂PO₁₂) solid-state electrolyte exhibits the ionic conductivity of 0.722 mS cm⁻¹ at 30 °C, and the activation energy of ∼0.237 eV. Its applicability in a solid-state battery is tested, and the assembled Na/Na₃V₂(PO₄)₃ (NVP) battery exhibits an outstanding electrochemical performance of 98.4% capacity retention after being cycled at 0.5 C. Moreover, DFT calculations also have been used to demonstrate the effect of doping on the crystal structure and space migration energy barrier. This research provides new ideas for improving the electrochemical properties of inorganic solid electrolytes.