基于SI4432的高性能无线收发应用平台设计

针对无线产品设计中的产品可靠性、功耗、有效距离和成本问题,设计了一款基于SI4432和STM32F103的高性能无线收发应用平台。设计中实现了ACK双向通信、精简CSMA/CA发送机制,增强了系统的可靠性,减少了由于数据冲突造成的数据丢失现象,可满足不同的应用需求。实验表明,该平台简化了无线产品的设计,可应用于安防、无线抄表、无线传感器网络等系统。     

移动机器车的WiFi接口设计

针对移动机器车在运行时状态参数难以实时检测的问题,设计了一个介于WiFi模块和STM32微控制器之间的无线传输接口。在该接口设计中,移动机器车中的微控制器STM32与WiFi模块之间采用SPI接口通信,并根据EM380的通信协议及时序,详细讨论了SPI接口的设计程序。最后通过利用VC软件设计的上位机软件,在Pc机上显示了赛车速度、赛道中心线等信息。实验结果验证了该无线接VI传输数据的有效性,表明无线检测将成为移动机器车状态参数检测的发展方向。     

On pseudo maximum likelihood estimation for multivariate time series models with conditional heteroskedasticity

We consider a general multivariate conditional heteroskedastic model under a conditional distribution that is not necessarily normal. This model contains autoregressive conditional heteroskedastic (ARCH) models as a special class. We use the pseudo maximum likelihood estimation method and derive a new estimator of the asymptotic variance matrix for the pseudo maximum likelihood estimator. We also study four special cases in this class, which are conditional heteroskedastic autoregressive moving-average models, regression models with ARCH errors, models with constant conditional correlations, and ARCH in mean models.     

Volatility dynamics of the US business cycle: A multivariate asymmetric GARCH approach

Most empirical investigations of the business cycles in the United States have excluded the dimension of asymmetric conditional volatility. This paper analyses the volatility dynamics of the US business cycle by comparing the performance of various multivariate generalised autoregressive conditional heteroskedasticity (GARCH) models. In particular, we propose two bivariate GARCH models to examine the evidence of volatility asymmetry and time-varying correlations concurrently, and then apply the proposed models to five sectors of Industrial Production of the United States. Our findings provide strong evidence of asymmetric conditional volatility in all sectors, and some support of time-varying correlations in various sectoral pairs. This has important policy implications for government to consider the effective countercyclical measures during recessions.     

On the convective nature of the instability of a front undergoing a supercritical Turing bifurcation

Fronts are traveling waves in spatially extended systems that connect two different spatially homogeneous rest states. If the rest state behind the front undergoes a supercritical Turing instability, then the front will also destabilize. On the linear level, however, the front will be only convectively unstable since perturbations will be pushed away from the front as it propagates. In other words, perturbations may grow but they can do so only behind the front. It is of interest to show that this behavior carries over to the full nonlinear system. It has been successfully done in a case study by Ghazaryan and Sandstede [A. Ghazaryan, B. Sandstede, Nonlinear convective instability of Turing-unstable fronts near onset: a case study, SIAM J. Appl. Dyn. Syst. 6 (2007) 319–347]. In the present paper, analogous results are obtained for the same system as in Ghazaryan and Sandstede (2007), but for a different parameter regime.     

基于RSView32实现圆形炼锌电炉自动控制系统

计算机技术和网络通信技术突飞猛进地发展,监控组态软件因为具有实时控制、联网通信、数据记录、人机对话等功能,被广泛地运用于PLC、DCS及FCS等系统中.以美国Rockwell公司的Rockwell RSView32工控组态软件实现对三相电极位置的调整,来控制三相电流平衡.并且实现温度压力在线监控和炉喉捅杆,沉降塔压力自动平衡等控制装置,应用于火法炼锌电炉中,取得了很好的效果.     

低成本单伺服注塑机械手控制系统设计

在注塑行业,注塑机械手已经逐渐替代人工操作并发挥着重要作用,而注塑机械手的精度又直接影响到注塑机的工艺和注塑件的质量.针对目前注塑机械手存在部分问题的现状,设计了一种基于STM32单片机的高精度低成本的注塑机械手控制系统,并对其硬件系统和软件系统做了详细的介绍.经过实验测试,注塑机械手达到了预期的功能和控制精度,但是其价格相比工业上的注塑机机械手降低了30％.     

基于STM32、以太网和ZigBee技术的智能家居系统的设计

论述的智能家居控制系统采用STM32Fl03ZET6最小系统作为控制器,以太网通信模块W5500作为系统网关,通过SPI总线实现控制器与网关的通信;被控设备通过ZigBee网络与协调器有机地结合起来,协调器通过串口通信协议与控制器进行通信.本系统具有成本低、体积小和实时性好等特点,有很高的使用价值.     

基于ZigBee和GPRS的电梯远程监控系统的设计

随着城市高层建筑的普及,电梯的使用量逐年增加,电梯安全性也受到越来越多的关注.本设计将ZigBee的短距离通信技术与GPRS远程通信技术结合,并在PC机上运用LabVIEW工具,设计了一种可对电梯进行远程监控的电梯监控系统.该监视系统由ZigBee模块、GPRS模块、STM32系列单片机及PC机4部分组成,可实现对电梯的实时监控、故障报警功能,具有低功耗、低成本、稳定性高等特点.将该监视系统运用于实际工况长期运行后,运行结果表明该监视系统运行稳定、可靠,能够大大提高电梯运行的安全性.     

基于STM32的智能温控杯控制系统设计

设计以ARM STM32F103作为系统控制核心,使用DS18B20测量温度,以半导体制冷器件作为降温设备,以PTC发热片作为升温设备,用LCD1602液晶进行显示,实现对杯内水温的有效控制。通过反复验证,该温控系统具有操作简单、精度较高、工作可靠和性价比高等特点。