Defensive secretion of rice bug,Leptocorisa oratorius fabricius, (Hemiptera: Coreidae): A unique chemical combination and its toxic,repellent, and alarm properties

Defensive secretion produced by adult males and females ofLeptocorisa oratorius, Fabricius (Hemiptera: Coreidae) living on the host plant,Oriza sativa, was analyzed by a combined gas chromatography-mass spectroscopy technique. Both male and female secretions consisted of two major components: (E)-2-octenal andn-octyl acetate, 76% and 16% (w/w), respectively. The remaining 8% were trace compounds, some of which were identified as hexyl acetate, 3-octenal, 1-octanol, and (Z)-3-octenyl acetate. In a survey among 38 coreid defensive secretions, (E)-2-octenal andn-octyl acetate were found to occur rarely in addition to coreid-specific compounds, while their combination as primary constituents was found to be unique. Toxicity and repellency of this secretion were evaluated using two household pests,Anoplolepis longipes andSitotroga cerealella, as test insects, and lethal concentration (LC₅₀) values of 0.24 ppm and 0.14 ppm, respectively, and repellencies of 63% and 58%, respectively, were obtained. Comparing the above values with those of a pentatomid bug,Coridius janus, evaluated under the same conditions, it was apparent that this secretion has potential as a repellent to enemies ofL. oratorius but not as a toxicant to attack them. Bioassay on the alarm activity of this secretion revealed that it elicits alarm responses, alerting and dispersing aggregated male and femaleL. oratorius: this is followed by self-coating activities. In addition, some unique behaviors were also noted among alarmedL. oratorius.     

基于MSP430的酒驾报警减速器的研制

以MSP430为核心控制器,利用测速器、FPGA、减速器、声光报警模块和LCD1602液晶显示器,设计了一款防止酒后驾车的汽车报警减速器,实现对车速的控制和平稳停车。对数据采集过程中对数据的处理方法以及控制汽车停车控制算法作了详细阐述,整个系统经调试,能运行正常。     

Fire fighting and its influence on the body

Working conditions for fire fighters can be described according to the environment temperature and the incident radiant heat flux. Measurements for this study in buildings for fire fighting training have shown that fire fighters are typically exposed to radiant heat fluxes of between 5 and 10 kWm ^-2 during this kind of exercise. The heat load can nevertheless be much higher. In one case, 42 kWm ^-2 was measured. The temperatures reached between 100 and 190°C at 1 m above ground, going up to 278°C in one case. Human trials have been performed with 17 fire fighters. After exercises (about 15 min) in a heated room, the mean core temperature of the fire fighters rose by 0.6°C with a surrounding temperature of 31°C and 1.0°C with 38°C. The sweat production varied from 0.7 to 2.1 lh ^-1; 16% to 45% of sweat remained in the clothing layers. During the exercises in the training buildings, a mean of 48°C has been measured between fire fighters' clothing and workwear. These conditions lead to an increase of the relative humidity in all the jackets up to 100%. When the fire fighters came out of the fire, the humidity remained at this level in the PVC coated jackets while it was in some cases strongly reduced in breathable jackets.     

Hypothesis testing analysis and unknown parameter estimation of GPS signal detection

Hypothesis testing analysis and unknown parameter estimation of both the intermediate frequency (IF) and baseband GPS signal detection are given by using the generalized likelihood ratio test (GLRT) approach, applying the model of GPS signal in white Gaussian noise. It is proved that the test statistic follows central or noncentral F distribution. It is also pointed out that the test statistic is nearly identical to central or noncentral chi-squared distribution because the processing samples are large enough to be considered as infinite in GPS acquisition problem. It is also proved that the probability of false alarm, the probability of detection and the threshold are affected largely when the hypothesis testing refers to the full pseudorandom noise (PRN) code phase and Doppler frequency search space cells instead of each individual cell. The performance of the test statistic is also given with combining the noncoherent integration.     

基于CAN总线的铁路道口控制系统

针对现有铁路道口信号控制系统“定点报警”方式对快速列车和慢速列车的速度不能识别,造成道口关闭时机不合理、影响道口通过效率等问题,提出了一种基于CAN总线技术的单线铁路区段道口控制系统解决方案：使用“定时报警”方式,并模块化设计单线铁路区段道口信号控制系统.道口信号控制系统在列车接近道口传感器时,采集列车的速度并适时启动报警.实验表明,该系统能实现设计要求,提高道口通过效率.     

Spacecraft rendezvous trajectory safety quantitative performance index eliminating probability dilution

In view of the probability dilution problem of the existing quantitative indexes of rendezvous trajectory safety performance using collision probability,this paper proposes a new quantitative index of rendezvous trajectory safety performance by well combining collision probability with warning threshold.The proposed new index increases monotonously as the position errors of the chaser spacecraft increase,therefore it can effectively overcome the problems of the reduction in the largest performance value and the advancement in the most dangerous time induced by the probability dilution.The proposed new index is applied to the safety design of close range rendezvous missions.The mission’s safety requirements for initial navigation precision and the safe region of initial and final keeping points’positions with a certain navigation precision are analyzed,and several valuable conclusions about the relation between position navigation precision and velocity navigation precision as well as the relation between keeping points’positions and navigation precision are obtained.     

Normal-distribution-test algorithm for range spread target detection

A range spread target detection algorithm based on the normal distribution test is proposed. Based on the fact that the range spread target signal generally does not follow normal distribution, the range spread target detection problem is equivalent to the normal distribution test problem. Analysis show that the normal distribution test detector has the characteristic of constant false alarm rate. The performance of the proposed detector is analyzed. Numerical experimental results based on simulation and measured high range resolution profile data show that the proposed detector outperform the energy integration detector.     

基于BP神经网络的入侵检测算法

为解决传统入侵检测算法存在的高漏报率及高误报率问题,结合BP神经网络算法的优点,提出一种采用遗传算法来优化BP神经网络算法的入侵检测算法。该算法通过遗传算法找到BP神经网络的最适合权值,采用优化的BP神经网络对网络入侵数据进行学习和检测,解决直接使用BP学习造成的训练样本数量过大而难以收敛的问题,同时缩短样本训练时间,提高BP神经网络分类正确率。仿真实验结果表明,与传统网络入侵检测算法相比,该算法的训练样本时间更短,具有较好的识别率和检测率。     

基于门限动态调整的最优协作检测方法

为提高协作频谱感知的检测效率、减少系统的反馈开销,提出一种基于门限动态调整的最优协作检测方法。在单节点检测错误概率最小的情况下,导出能量检测中门限值与信噪比的关系表达式,利用二分法求得不同信噪比下的动态门限值。根据系统恒虚警率和恒检测率计算最优协作用户数,并与动态门限值相结合得到系统检测错误概率。仿真结果表明,该方法协作检测概率较高,检测错误概率较低。     

基于STM32和ZigBee的无线校园火灾报警系统设计

结合校园防火报警需要,设计了基于ZigBee技术的无线校园防火报警系统。该系统以意法半导体公司推出的STM32系列ARM控制器、TI公司的CC2420无线射频芯片为核心,对无线传感器网络中的终端节点、路由器节点、协调器节点的硬件和软件进行了模块化设计。传感器节点以温度、烟雾和CO浓度为实现监测对象,判断是否有火灾隐患,从而实现校园防火报警系统的无线网络化。