机车摇枕断裂分析

采用宏、微观检验和电子探针等方法对断裂摇枕进行了分析。结果表明,由于热处理不当造成三次渗碳体在铁素体中呈网状析出,致使材料塑性和冲击功大幅度降低。重新热处理后力学性能符合难收标准。     

热电偶无线传感器节点低功耗优化设计

针对飞行器内部线缆复杂度高、布线困难的问题,提出采用无线通信模式来提高传感器部署的灵活性,减少线缆运输和安装成本;为了最大程度地延长无线传感器节点的使用寿命,对热电偶无线传感器进行了节点低功耗优化设计;硬件方面,基于DPM机制设计了能量分块管理模型,核心处理器采用国产低功耗芯片GD32E230C8T6;软件方面,提出了一种基于星型拓扑结构无线传感器网络的低功耗策略,并基于此策略给出节点剩余能量数学表达式;实验结果表明,此节点处于停机储运状态下的电流低于1μA,待机模式下的电流低于23 mA,证实了所设计的热电偶无线传感器具有低功耗、稳定的特点,能有效延长节点寿命。     

~(230)Ac的β延发裂变

用 6 0MeV/u18O离子轰击ThO2 ,通过多核子转移和靶的耗散碎裂反应产生2 3 0 Ra。利用放射化学分离技术 ,将镭与钍及其它反应产物分离并制备成薄镭源。该源对云母裂变径迹探测器暴光 ,用高纯锗探测器测量镭源的γ活度 ;用氢氟酸溶液对云母箔进行蚀刻 ,使用光学显微镜观测云母箔中的裂变径迹。首次观测到了可能来自2 3 0 Acβ延发裂变的两个事件 ,获得它的 β延发裂变几率为 (1 19± 0 85 )× 10 -8。     

托卡马克HT-7U低温超导磁体的绝缘系统

主要介绍低温超导托卡马克HT-7U中磁体的绝缘结构,绝缘材料的特性,绝缘结构形成的工艺,绝缘层的电性能和力学性能等。     

一种国产新型易加工氯丁橡胶

介绍ＣＲ２３０－ＥＰ氯丁橡胶的聚合与性能的关系以及同ＣＲ－２３０、美国ＴＷ胶的对比。     

Education, cost of living and regional wage inequality in Brazil

The objective of this article is to analyze wage inequality among the 10 largest metropolitan regions in Brazil in the 1990s. We assess the extent to which worker characteristics (education, age, gender, race, position in the family) and job characteristics (occupational position, sector, experience) can explain wage inequality. The analysis is made both with regional-nominal and with regional-real wage data. In the second case regional price indexes are used to control for differences in cost of living among regions. Wage differentials in Brazil were slightly lowered when control variables were introduced, but the leftover inequality remained high. The results indicate that cost of living levels do have a role in explaining wage inequality in Brazil, but even after controlling for this factor, the remaining regional differentials are still important. Received: 18 August 2000 / Accepted: 20 June 2001     

基于FPGA的电力无线专网频谱感知系统

针对230 MHz频段的频谱感知实现,本文设计了基于AD9364及FPGA的硬件系统。为了实现较高的频谱分辨率,采用数字信道化的方法,增加FFT计算的点数,最终的频谱分辨率为100 Hz。系统中的频谱感知采取能量检测的方法,该方法有效且易于实现,当信噪比大于3 dBm时,可以判断该频谱被占用。数字信道化及FFT均在FPGA中实现,频谱拼接和能量检测则在MATLAB中实现。通过多次的仿真测试可以证明该系统有效。     

LTE800MHz非标带宽频率再重耕研究与分析

为了提高LTE800M网络容量和用户速率，提升用户感知，从理论上分析了非标带宽再重耕原理机制，通过试点分析其效果及影响，为下一步800M非标带宽重耕实施提出合理的建议。     

氘化闪烁体的光响应

在迴旋加速器上利用D(d,n)~3He反应和~9Be(d,n)~(10)B反应产生的中子,采用双参数方法测量NE-230和NE-232氘化闪烁体对氘以及国产的ST-451闪烁体对质子的光响应曲线,所测的实验值用二次多项式拟合。对其它性能也作了相对比较。     

High temperature dielectric properties measurement system at 915 MHz based on deep learning

A ridged waveguide and heating system based on deep learning for dynamic measurement of dielectric properties at high temperatures has been developed. Firstly, specially designed ridged waveguide at the frequency of 915 MHz was utilized. The finite difference time domain simulation was then combined with the deep learning algorithm to construct the dielectric properties. In addition, the calibration method based on a two‐point algorithm was involved in the network. The precision of the measured dielectric constant and loss tangent was improved by 4.4% and 1.9%, respectively. Simulated results indicated that the deep learning algorithm had higher accuracy than back propagation neural networks and support vector machine algorithms. The reliability of the system was verified by Si₃N₄ and alcohols at room temperature. The dielectric properties of quartz particles were also tested over a temperature range up to 900°C. The experiment results agreed well with the reference values. This system can measure a wider range of dielectric properties and achieve higher accuracy using the advanced deep learning algorithm. It is more convenient to measure large size materials in industrial applications at high temperatures.