冲击荷载下含裂纹缺口三点弯动态断裂实验

为研究缺口大小对含裂纹缺口构件动态断裂的影响,采用动态光弹性实验方法,对含裂纹缺口试件进行了冲击实验.基于冲击断裂过程中试件的等差条纹变化图片和动态应变仪采集的应变数据,分析了冲击荷载下裂纹尖端的动态应力强度因子、裂纹扩展速度和锤头应变的变化规律.结果表明:不同缺口角度试件受到冲击荷载后,应力强度因子的变化随时间变化的...     

基于最小发射功率的自适应调制多输入多输出系统

在对多输入多输出信道进行奇异值分解的基础上,推荐了一种新的最小化发射功率的自适应调制算法.通过在不同信道假设条件下的性能仿真,证明了推荐算法能够在满足用户要求服务质量的条件下,以尽可能小的系统发射功率实现数据传输.     

不同厚度三点弯曲梁的裂纹扩展动态焦散实验

采用动态焦散线实验方法,对冲击作用下不同厚度的三点弯曲梁进行了研究,分析了厚度对其动态断裂过程的影响.结果表明:不同厚度三点弯曲梁在动态冲击实验中,预制裂纹起裂时间和扩展时间受到试件厚度的影响.厚度越大,起裂越慢,扩展时间越长;试件起裂后,不同厚度下裂尖的扩展速度和动态应力强度因子值随时间的变化曲线均呈现先快速上升后波...     

雷达与ESM综合多目标检测、跟踪与识别

为在预警监视系统中对多目标的检测、跟踪、识别过程进行统一处理,提出一种基于跳转马尔可夫系统模型高斯混合概率假设密度滤波(jump Markov system model Gaussian mixture probability hypothesis density filtering,JMS-GMPHDF)算法的雷达、电子支援措施（electronic support measures,ESM）综合多目标检测、跟踪与识别方法。该方法首先根据不同类别目标设计各自的多目标多模型高斯混合概率假设密度滤波器,并在各滤波器处理过程中同时对高斯项进行编号;然后,根据目标速度与加速度模型信息进行高斯项综合与类别判决,同时根据ESM测量信息进行型号判决;最后,通过航迹综合管理,形成具有运动状态信息以及类别、型号、航迹编号信息的确定航迹。仿真实验验证了该方法能够有效综合雷达、ESM测量数据,在进行多目标检测、跟踪的同时进行正确的类别、型号判决,并形成确定航迹。     

Optimal policy with a total order quantity commitment contract in the presence of a spot market

In this paper,the optimal policy is considered when the buyer faces two supply sources:one is the contract supplier from which the buyer orders over a specific contract period(say,a year) at a pre-agreed price,and the other is the spot market.However,when ordering from the contract supplier,the buyer must fulfill a pre-determined total order quantity,or the so-called definite total order quantity commitment,over the whole contract period.In other words,the commitment secures the buyer a fixed price but obliges him/her a total order quantity over the contract period.Although the spot market gives the buyer more flexibility in terms of order quantities,its prices are volatile.Such a combination of contract and spot procurements is often observed in practice.Within the contract period,there are multiple sub-periods,during each of which the buyer reviews the inventory,issues an individual order,and uses the on-hand inventory to meet the random demand.Thus,in each(ordering) period,the buyer will weigh between the current known spot price(by procuring from the spot market) and a lower future price(by waiting while consuming the remaining commitment).An optimal dual ordering policy is characterized for each period,depending on the on-hand inventory level,the spot price,and the remaining commitment quantity.The optimal policy in each period is also shown to be independent of the contract price.Through a numerical study,the inventory cost is demonstrated to be(1) insensitive to the contract price when the total commitment quantity is lower than the total expected demand over the contract period and(2) non-increasing in the variability of spot prices.     

Integrated heat and power dispatch model for wind-CHP system with solid heat storage device based on robust stochastic theory

This paper built a combined heat and power (CHP) dispatch model for wind-CHP system with solid heat storage device (SHS) aiming at minimizing system coal consumption, and set system demand-supply balance and units’ operation conditions as the operation constraints. Furthermore, robust stochastic optimization theory was used to describe wind power output uncertainty. The simulation result showed that SHS increased CHP peak-valley shifting capability and reduced abandoned wind rate from 12% to 6%, and reduced 5% coal consumption, compared with the original system operation by flexible charging electric power and heating. The payback period of employing SHS in wind-CHP system is far shorter than SHS expected service life.     

_n型Hecke代数的一个不可约复表示

设Ｗ＝（Ｗ，Ｓ）是型仿射Ｗｅｙｌ群，Ｈ和分别是型的Ｈｅｃｋｅ代数和扩充Ｈｅｃｋｅ代数．由Ｗ中合ｓ０ｓ１的双边胞腔的分解，可以得到一个Ｗ－图τ．文中讨论了与τ相应的的复表示为平方可积（相应地，反平方可积，调合与反调合）的充要条件，以及与τ相应的Ｈ的复表示为不可约的充要条件，最后，得出与的不可约复表示相对应的代数簇（ＳФ，ＮФ）由２ｎ个孤立点组成．     

基于GMM和MRF的自适应阴影检测

运动目标阴影在很大程度上会影响运动目标跟踪、行为识别的正确性和有效性.为此,文中提出了一种基于混合高斯模型和马尔科夫随机场的自适应阴影检测方法.该方法首先对混合高斯模型进行改进,使其可以自适应调整参数学习率以消除浅阴影;然后采用马尔科夫随机场综合邻域的空间依赖性信息进行精确的阴影检测.为了提高基于马尔科夫随机场的阴影检...     

基于FPGA的光伏并网逆变器控制系统的研究

提出一种利用FPGA实现的光伏并网逆变器控制系统.在分析Boost型DC/DC转换器和电压源型逆变器组成的光伏并网逆变器硬件结构的基础上,对最大功率跟踪、SVPWM调制、并网控制等关键控制环节进行了研究,通过在FPGA内搭建AD采样控制、数据处理、最大功率算法、SVPWM发生、PI控制器、数字锁相环等模块实现该控制系统.搭建应用该控制系统的3kW光伏并网逆变器样机,在分布式发电实验平台运行,结果验证了该FPGA控制系统的可靠性,证明了其并行运算能力有助于提高控制效率和光伏并网系统的输出电能质量.     

中国饮食文化中的哲学思想

饮食文化在中国文化中有非常重要的地位,中国人不但创造了举世闻名的中国美食,而且还把“吃”作为不可替代的一种生活享受乃至生活的艺术。中国的饮食文化是由中国民族文化的积淀而形成的,潜在地含蕴着大量的哲学因素,这就使得中国古代哲学思想不仅可以直接从饮食中产生,而且也可以建立在这种生活基础之上。“阴阳五行”的哲学思想、“天人合一”的哲学思想、“中和为美”的哲学思想、“以食疗病”的哲学思想、“烹饪喻治国”的哲学思想体现出中国文化的博大精深。