PWM激励下异步电机铁耗等值电阻模型

通过分析PWM激励下异步电机铁耗变化的特点,提出了一种综合考虑电机运行工况和PWM波形特性的铁耗等值电阻模型。基于铁耗分离原理,使用三个电阻分别等效电机铁耗的磁滞分量、经典涡流分量和异常涡流分量,并推导了正弦激励下各个电阻分量的表达式;进而通过分析PWM激励与正弦激励下铁耗间关系,对正弦激励下铁耗模型进行修正,获得PWM激励下铁耗模型;最后提出了确定该模型参数的实验方案。所建模型中各个电阻分量随电机运行频率和PWM波形的调制系数变化而变化,且变化规律各不相同,提高了电机铁耗计算的准确性。仿真和实验验证了该模型的正确性和有效性。     

Characterization of germanium implanted Si1−xGex layer

Characterization of a Si_1−xGe_x layer formed by high-dose germanium implantation and subsequent solid phase epitaxy is reported. Properties of this layer are obtained from electrical measurements on diodes and transistors fabricated in this layer. Results are compared with those of the silicon control devices. It was observed that the germanium implantation created considerable defects that are difficult to eliminate with annealing. These defects result in boron deactivation in the p-type regions of the devices, giving rise to larger resistance. Optimization of the device structure and fabrication process is discussed.     

H2S-Activated Ion-Interference Therapy: A Novel Tumor Targeted Therapy Based on Copper-Overload-Mediated Cuproptosis and Pyroptosis

Copper overload is a novel way to achieve copper-ion-interference therapy by disrupting copper homeostasis and treating diseases through multiple cell death pathways. However, it is difficult to reach copper overload since excess intracellular copper ions will be pumped out. Herein, copper overload is achieved by both raising cellular uptake and reducing the efflux of copper ions using hydrogen sulfide (H₂S)-responsive copper hydroxyphosphate nanoparticles (Cu₂(PO₄)(OH) NPs). After immersion in an H₂S-enriched colon cancer microenvironment, Cu₂(PO₄)(OH) NPs can transform into copper sulfide NPs with reduced size for higher cell entering, resulting in improved Fenton activity as well as copper ion dissociation. Reactive oxygen species generated by the Fenton reaction not only activate inflammasomes and Caspase-1 proteins, cause the cleavage of gasdermin D to induce pyroptosis, but also affect mitochondrial function and down-regulate copper exporter ATP7A to further reduce the copper excretion. The combination of higher endocytosis and lower exportation leads to maximized copper overload. Together with the efficient copper ions release, mitochondrial tricarboxylic acid cycle can be disrupted and iron-sulfur cluster proteins are downregulated, ultimately triggering cuproptosis. As both pyroptosis and cuproptosis are efficient ways to induce cell death, this study provides a novel way to realize effective tumor-targeted therapy based on H₂S-activated copper overload with simple Cu₂(PO₄)(OH) NPs.     

3G无线网络建设问题探讨

移动通信低速语音通信向高速数据通信转变,通信业务由室外向室内转移,无线网络从信号覆盖型向信息容量型演进,网络架构正在发生深刻变革。变革对网络建设、技术和管理提出了新的挑战和要求。针对存在的问题和挑战,提出了相关建议,并介绍了广东联通在技术和管理创新方面的有益尝试。     

毫米波三基线InSAR系统误差校正和信号分析

该文研究了毫米波三基线InSAR系统误差校正问题,给出了系统误差校正方案,以实现三通道信号间的幅相一致性。分析了脉冲压缩处理的效果、通道间的干扰影响、系统相位稳定性、慢时间频谱、幅相一致性程度。给出了三基线干涉测角去模糊的方法以及地面测试实验方案。地面实测数据的处理和分析结果,验证了该文方法的有效性,并检验了该毫米波三基线InSAR的系统性能。     

PLC实训项目的组态开发与设计

介绍了利用组态技术实现PLC实训项目的虚拟控制。把该系统应用于实验教学中,它可以对PLC实训项目的运行状态进行虚拟监控,达到更好的实验效果。     

GHz band frequency hopping PLL-based frequency synthesizers

In this paper we describe a full-integrated circuit containing all building blocks of a completed PLL-based synthesizer except for low pass filter（LPF）. The frequency synthesizer is designed for a frequency hopping （FH） transceiver operating up to 1.5 GHz as a local oscillator. The architecture of Voltage Controlled Oscillator （VCO） is optimized to get better performance, and a phase noise of -111.85-dBc/Hz @ 1 MHz and a tuning range of 250 MHz are gained at a centre frequency of 1.35 GHz. A novel Dual-Modulus Prescaler（DMP） is designed to achieve a very low jitter and a lower power. The settling time of PLL is 80 μs while the reference frequency is 400 KHz. This monolithic frequency synthesizer is to integrate all main building blocks of PLL except for the low pass filter, with a maximum VCO output frequency of 1.5 GHz, and is fabricated with a 0.18 μm mixed signal CMOS process. Low power dissipation, low phase noise, large tuning range and fast settling time are gained in this design.     

变频器在数控机床中的应用探讨

本文主要讲述了三菱变频器在数控机床中的应用，三菱变频器因其性能优越被广泛地应用在现代工业领域中，特别是它的矢量控制、直接转矩控制等，为数控机床的控制提供了传动的最佳解决方案，从而提高了数控机床的整机性能。     

电子产品环境与可靠性试验应力研究

本文从有关标准入手,论述了环境试验与可靠性试验的基本概念及相互关系,重点介绍了环境试验和可靠性试验在应力施加上的异同点,指出了进行这两项试验的重要性。     

天基跟踪层星座性能建模与仿真

随着高超声速武器技术的快速发展和实战化部署,美国有针对性地提出了建设国防太空架构跟踪层计划的设想。首先,介绍了跟踪层卫星主要设计性能参数;其次,建立了跟踪层星座覆盖性能分析模型、探测能力分析模型和跟踪性能分析模型;最后,通过仿真计算对跟踪层系统性能进行了分析,并推断了系统全星座最小卫星数量、探测灵敏度和全球目标最优跟踪精度等核心能力。分析结果对相关系统信息处理算法研究、载荷与星座方案设计具有重要参考价值。