一种3.5 GHz频段双通道射频前端设计

随着5G商用网络的快速建设,国内5G网络测试设备存在大量空缺。为此,设计了一种适用于5G终端模拟器的3.5 GHz频段双通道射频前端。该射频前端结合了ADRV9009芯片,可同时支持双通道收发,具有器件数少、设计复杂度低的特点。实测结果表明,该射频前端性能稳定,接收灵敏度为-85 dBm,噪声系数小于2.6 dB,256QAM调制下发射信号的误差矢量幅度为1.43%,达到了5G终端模拟器的设计要求。     

Statistical Implementations of Agent-Based Demographic Models

A variety of demographic statistical models exist for studying population dynamics when individuals can be tracked over time. In cases where data are missing due to imperfect detection of individuals, the associated measurement error can be accommodated under certain study designs (e.g. those that involve multiple surveys or replication). However, the interaction of the measurement error and the underlying dynamic process can complicate the implementation of statistical agent-based models (ABMs) for population demography. In a Bayesian setting, traditional computational algorithms for fitting hierarchical demographic models can be prohibitively cumbersome to construct. Thus, we discuss a variety of approaches for fitting statistical ABMs to data and demonstrate how to use multi-stage recursive Bayesian computing and statistical emulators to fit models in such a way that alleviates the need to have analytical knowledge of the ABM likelihood. Using two examples, a demographic model for survival and a compartment model for COVID-19, we illustrate statistical procedures for implementing ABMs. The approaches we describe are intuitive and accessible for practitioners and can be parallelised easily for additional computational efficiency.     

单片机仿真器设计关键技术分析

本文讨论了一种以MCS-5l系列单片机为基础的仿真器的设计制作及应用。本仿真器采用广为应用的89C52单片机为核心,可以运行著名的Keil Monitor—51监控程序。通过PC机运行KeilμVision 2集成开发调试环境软件,本仿真器可以进行单片机硬件调试以及C语言(Keil C51)和汇编语言软件的开发与调试。系统设计合理,成本低廉,制作方便,应用广泛。     

The Land Use Impacts of the EU Biodiesel Policy: Assessing the Direct,Indirect and Induced Effects

This paper deals with the controversial measure of indirect land use changes of the European biodiesel policy. Two studies sponsored by the European Commission find significant, but contrasted, land use impacts for the different vegetable oils used for biodiesel production. The first study uses an aggregate computable general equilibrium model capturing direct, indirect and induced effects. The second more recent study uses a biotechnical partial equilibrium model providing a detailed representation of the indirect effects occurring through the livestock sectors. We develop an original economic emulator to understand the diverging key results of these studies and test their sensitivity. We find that the direct and indirect effects on vegetable oil and land markets explain most of the differences. We also find that indirect effects on the feed markets and the induced effects have less influence on the biodiesel results. We finally argue that the development of emulators as done here can help to understand complex policy assessments.     

时变多普勒衰落信道硬件模拟的FPGA实现

针对不同散射环境下衰落信道具有不同的多普勒功率谱形状,提出了一种改进的复谐波叠加模型用于时变多普勒衰落信道的模拟,仿真分析了该方法输出信道衰落的幅值及相位连续性,并据此设计了基于FPGA硬件平台的时变多普勒衰落信道模拟器。硬件实测结果表明,该模拟器输出的时变多普勒功率谱与理论仿真非常吻合,可用于实际中多普勒功率谱实时变化场景的模拟。