低碳型机场接送服务的改进二维扫描算法

以航空客票公司接送顾客到机场的服务为背景,研究通过管理优化降低车辆碳排放量的方法.在车辆碳排放量定量表示的基础上,建立了低碳型机场接送服务的数学模型.借鉴经典扫描算法,并针对低碳型机场接送服务空间维和时间维的二维属性,提出了一种改进的二维扫描算法ITDSA(improvedtwodimensionalsweepalgorithm).利用改进的二维扫描算法对实例进行了计算,并通过对实例结果的分析,探讨了机场接送服务中顾客满意度和碳排放之间的关系,当顾客满意度为85%时,碳排放量相对较低.     

一种改进的多带宽干线协调控制模型

针对经典的多带宽干线协调控制模型——MULTIBAND中绿波带按照一条中心线严格对称造成的求解范围小和绿波带在绿灯时段内的位置不合理造成的绿波不稳定两个问题,从取消绿波带中心线对称和增加绿波带位置约束两方面入手,提出一种改进的MULTIBAND干线协调控制模型.改进后的模型提出了非对称式绿波的概念,允许不同路段上的绿波具有一定的灵活性,不拘泥于与其他路段绿波构成连续对称;同时增加了绿波带位置的约束,使得求解出的绿波带会尽量靠近上下游绿灯的中间位置,提高绿波运行的稳定性.以临沂市沂蒙路8个相邻交叉口的干线协调控制设计为例,用VISSIM仿真软件对改进后的模型进行了仿真测试和评价.结果表明,改进后的模型在绿波带宽与绿灯时间比值方面增加了7.1%,在延误和停车次数方面分别减少了20.8%和30.8%.     

风险规避型零售商的链与链竞争两部定价合同

以批发价格为基准,构建了需求不确定环境下两个风险中性制造商和两个排他性的绝对风险规避型零售商的链与链价格竞争模型,从制造商和零售商均实现Pareto绩效改进的双赢角度识别了两部定价合同选择的博弈均衡特征和局限性,并分析了市场需求风险、零售商的风险规避程度及产品的价格竞争对两部定价合同选择的影响.研究结论表明,当价格竞争强度相对较弱且严重依赖于需求风险和零售商的风险规避程度,则通过调节固定收费在适当范围内时,两部定价合同是实现制造商和零售商Pareto绩效均改进的占优均衡合同;当价格竞争加剧并超过特定边界值时,该固定收费均衡区域消失.     

朱光潜的京派审美情趣——从朱光潜与鲁迅的分歧说起

20世纪30年代朱光潜与鲁迅的分歧,是京派与左翼审美趣味的分歧,也是“看戏”与“演戏”人生理想的分歧。朱光潜以中国传统文人士大夫的审美情趣青睐于西方古典主义的“静穆说”,把“静穆”视为艺术的极境,貌似很西方,实则很古典。     

管材塑性弯曲成形的有限元数值模拟分析

为深入研究管材塑性弯曲成形机理,利用数值模拟方法建立了包括工艺参数在内的管材弯曲成形全参数化有限元模型,并验证了模型的有效性.在此基础上,详细分析了管材弯曲变形过程中的应力应变分布.结果表明,最大等效应力发生在弯管起弯侧,最大等效应变则沿弯管变形区域均匀分布,管材弯曲成形处于平面应力状态和三向应变状态.     

虚拟参考反馈校正控制器参数的预测误差辨识

针对未知系统中双控制器的设计问题,采用虚拟参考反馈校正方法,通过最小化由一组观测数据组成的L2范数所构成的代价函数,达到直接设计控制器目的.联合前馈控制器分离出的固定部分和反馈控制器作为滤波器,对原输入/输出关系式进行重参数化,得到标准的预测误差辨识形式,在所得式中,对控制器未知参数矢量采用可分离迭代的非线性最小二乘法进行估算.文中还对算法的收敛性进行了理论分析,并通过仿真验证了所提方法的有效性.     

双刃斜角切削中流屑角的变化规律

流屑角是金属切削过程中的重要特征参数.目前,人们对于前角和刃倾角均不为0°的双刃斜角切削的流屑角尚没有形成统一的认识.文中研究了前角和刃倾角均不为零的双刃斜角切削的流屑角.通过建立切削模型,并根据切削深度和进给量的不同,导出两种不同的模型,系统地研究了前角、安装倾角、刀尖角、进给量和切削深度变化时流屑角的变化规律,并通过实验进行验证.理论预测与实验结果吻合得较好,说明所提出的模型可以用来预测双刃斜角切削的流屑角.     

Development and characterization of interspecific hybrids between <Emphasis Type="Italic">Oryza sativa</Emphasis> and <Subscript>O. latifolia</Subscript> by <Subscript>in situ</Subscript> hybridization

Oryza sativa and O. latifolia belong to the AA and CCDD genomes of Oryza, respectively. In this study, interspecific hybrids of these species were obtained using the embryo rescue technique. Hybrid panicle traits, such as long awns, small grain, exoteric large purple stigma, grain shattering and dispersed panicles, resemble that of the paternal parent, O. latifolia, whereas there is obvious heterosis in such respects as plant height, tillering ability and vegetative vigor. Chromosome pairing and the genomic components of the hybrid were subsequently investigated using genomic in situ hybridization （GISH） and fluorescent in situ hybridization （FISH） analysis. Based on the mitotic metaphase chromosome numbers of the root tips investigated, the hybrid is a triploid with 36 chromosomes. The genomic constitution of the hybrid is ACD. In the meiotic metaphase Ⅰ of the hybrid pollen mother cell, poor chromosome pairing was identified and most of the chromosomes were univalent, which resulted in complete male sterility in the hybrid.     

Effects of dietary nickel on detoxification enzyme activities in the midgut of <Emphasis Type="Italic">Spodoptera litura</Emphasis> Fabricius larvae

Nickel accumulated in midugt of Spodoptera litura Fabricius could induce the expression of metallothionein, one of the most important detoxification proteins in organisms. In the present study, the effects of dietary nickel on the activities of detoxification enzymes, such as carboxylesterase （CarE） and giutathione S-transferase （GST） in the midgut of S. litura larvae have been studied to get an understanding of the detoxification mechanisms of S. litura larvae to excessive nickel. Results showed that CarE activities in the midgut of the 5th instar larvae decreased at lower levels of nickel （≤5 mg/kg）, while increased with increasing nickel doses at higher levels of nickel （≥10 mg/kg） exposure in successive 3 generations. CarE activities of the 6th instar larvae were also characterized as inhibited at low levels of nickel exposure, and improved at higher levels in the 1st generation. CarE activities of 6th instar larvae in the 2nd and 3rd generations were all lower than that in control. However, GST activities in the midgut of the 5th and 6th instar larvae all increased with increasing nickel doses （1 --20 mg/kg） in diets.     

Structures of magnetic null points in reconnection diffusion region: Cluster observations

Magnetic reconnection is a very important and fundamental plasma process in transferring energy from magnetic field into plasma. Previous theory, numerical simulations and observations mostly concentrate on 2-dimensional （2D） model; however, magnetic reconnection is a 3-dimensional （3D） nonlinear process in nature. The properties of reconnection in 3D and its associated singular structure have not been resolved completely. Here we investigate the structures and charactedstics of null points inside the reconnection diffusion region by introducing the discretized Poincar6 index through Gauss integral and using magnetic field data with high resolution from the four satellites of Cluster mission. We estimate the velocity and trajectory of null points by calculating its position in different times, and compare and discuss the observations with different reconnection models with null points based on characteristics of electric current around null points.