基于计算机视觉的架空线近距离预警系统

在户外工作环境中,由于机械设备臂展较长以及操作过程中受设备操作人员的注意力、判断力、视线范围的限制,极易发生作业设备与架空线相碰而引发的电力事故,因此设计并实现了一种架空线近距离预警系统.该系统由两个摄像头负责采集实时环境图像,根据透视投影模型,由矫正过后图像中的点与标定板上点的映射关系以及两个摄像头的坐标位置,计算出目标物的物理坐标,再求得目标物和架空线之间距离,若小于安全距离则报警.仿真实验结果表明:预警系统具有良好的实时性和准确性,能够满足一定范围内的预警需求.     

论《大浴女》的历史叙事

铁凝在长篇小说《大浴女》中采用灵活多变的叙述视角,对文革历史进行独特的书写,对女性的生存状态与情感历程进行理性描绘,试图从历史发展和文化传统的角度阐释女性的历史命运,从而使小说呈现出独特的历史叙事风格。     

基于进化博弈的交通安全分析

运用进化博弈理论研究交通安全问题,构建交通出行者群体之间以及交通出行者群体与交通管理部门之间的博弈模型及其复制动态方程,并对复制动态方程做了分析与讨论,得到了博弈模型中各博弈方的进化稳定策略,并根据所提出的博弈模型,提出了减少我国交通安全事故的合理性建议.     

一种鲁棒的非平坦路面车道线检测算法

提出了一种鲁棒的非平坦路面车道线检测算法. 给出一种简单的逆透视变换方法,该方法不依赖于摄像机参数,计算简便. 基于法向车道线模型研究了车道线的线特征提取方法,结合线特征的方向特性和强度信息,提出了改进的Hough变换车道线直线检测方法,有效提高了检测的鲁棒性和计算速度. 利用检测出的直线对车道线进行精确定位,采用加权最小二乘曲线拟合方法完整地提取出图像中的车道线. 实验证明,算法在弯道和非平坦路面上都能准确地提取出车道线,具有较强的鲁棒性.      

我国少数民族地区贫困问题探讨——以西藏为例

以西藏为代表的我国少数民族地区的贫困问题,其形成原因有很多。除了历史、文化、区域等因素之外,经济因素同样非常重要。文章分别从经济视角与非经济视角对以西藏为代表的我国少数民族地区贫困问题进行分析。从经济视角看,由于在固定资产投资、储蓄、人力资本水平以及研发水平等方面存在较大的差距,西藏经济比较接近于发展经济学中的贫困陷阱;从非经济视角看,主要利用西藏日喀则地区若干家庭问卷调查结果的微观数据来分析贫困的形成原因,发现被调查家庭的区域特征、人口特征以及社会资源特征等方面对贫困的产生具有较大的影响。     

Distinct but parallel evolutionary patterns between alcohol and aldehyde dehydrogenases: addition of fish/human betaine aldehyde dehydrogenase divergence

Alcohol dehydrogenases (ADHs) of the MDR type (medium-chain dehydrogenases/reductases) have diverged into two evolutionary groups in eukaryotes: a set of 'constant' enzymes (class III) typical of basal enzymes, and a set of 'variable' enzymes (remaining classes) suggesting 'evolving' forms. The variable set has larger overall variability, different segment variability, and variability also in functional segments. Using a major aldehyde dehydrogenase (ALDH) from cod liver and fish ALDHs deduced from the draft genome sequence of Fugu rubripes (Japanese puffer fish), we found that ALDHs form more complex patterns than the ADHs. Nevertheless, ALDHs also group into 'constant' and 'variable' sets, have separate segment variabilities, and distinct functions. Betaine ALDH (class 9 ALDH) is 'constant,' has three segments of variability, all non-functional, and a limited fish/human divergence, reminiscent of the ADH class III pattern. Enzymatic properties of fish betaine ALDH were also determined. Although all ALDH patterns are still not known, overall patterns are related to those of ADH, and group separations may be distinguished. The results can be interpreted functionally, support ALDH isozyme distinctions, and assign properties to the multiplicities of the ADH and ALDH enzymes.     

Oligo-1,6-glucosidase and neopullulanase enzyme subfamilies from the alpha-amylase family defined by the fifth conserved sequence region

The α-amylase enzyme family is the largest family of glycoside hydrolases. It contains almost 30 different enzyme specificities covering hydrolases, transferases and isomerases. Some of the enzyme specificities from the family are closely related, others less so. This study, based on the analysis of 79 amino acid sequences, postulates two subfamilies in the framework of the α-amylase family: the oligo-1,6-glucosidase subfamily and the neopullulanase subfamily. The specific sequence in the fifth conserved sequence region of the family served as the basis for defining the subfamilies: QpDln for the oligo-1,6-glucosidase subfamily and MPKln for the neopullulanase subfamily. This conserved sequence region is proposed to be the selection marker that enables one to distinguish between the two subfamilies. The 'intermediary' sequence MPDLN can be characteristic of the so-called intermediary group with a mixed enzyme specificity of α-amylase, cyclomaltodextrinase and neopullulanase. The evolutionary trees clearly supported the proposed definition of the two subfamilies. Received 12 July 2002; received after revision 28 August 2002; accepted 24 September 2002 RID="*" ID="*"Corresponding author.     

The tuning of moth ears

Summary The simple ears of months have responded evolutionarily to the varied levels of selection pressure exerted upon them by insectivorous bats. While frequency-matched (syntonic) bats exert the primary pressure that determines where a sypatric moth's best frequency (BF) lies, there are bats that echolocate in mismatched (allotonic) bandwidths forming selection pressures strong enough to warrant increased secondary sensitivity at these frequencies. It is unknown what neural mechanism is used by these insects to broaden their audiograms but for some neotropical moths, external hearing aids provide a mechanical means of obtaining this sensitivity. Recent studies have uncovered social uses for auditory systems in certain moths and these requirements may provide additional selection pressure. Auditory conditions exist in certain moths that should provide a means to study the evolution of this sensory system from its mechanoreceptor origins to its degeneration in the absence of bat predation.     

基于演化博弈的平台电商信用监管机制研究

在既有研究提出平台交易市场信用"监管困局"的基础上，设计平台电商信用监管机制，基于此，构建由"平台卖家-平台电商-政府"集成的演化博弈模型，剖析平台电商信用"监管困局"的内在形成机理并加以破解.研究发现：当平台卖家采取"自律"策略的初始概率一定时，平台电商与平台卖家两个群体策略选择的演化轨迹呈周期性波动.具体而言，当平台电商提高保证金扣除比例时，平台卖家选择"自律"策略的概率则会显著提高.而当累计扣分制致使平台卖家的损失增加时，不但没有遏制平台卖家的违规行为，反而使得平台卖家采取"自律"策略的概率降低，是为平台交易市场信用"监管困局"的症结所在.因此，为了弥补平台电商对平台卖家内部监管的不足，引入政府对平台电商的外部监管，有限理性的平台电商与政府通过长期的反复博弈，最终博弈系统演化轨迹呈逐渐收敛且稳定的趋势.由此可见，政府加强监管力度并增加对平台电商的监管奖励时，平台电商采取"积极监管"策略的概率也逐渐增加，进而平台卖家采取"自律"策略的概率也将增加，是为破解平台交易市场信用"监管困局"的关键所在.最后，本文采用数值分析的方法，模拟"平台卖家-平台电商-政府"博弈的演化过程，进一步剖析该现象的动态形成过程，揭示各主体决策的一般规律，为破解平台交易市场中的信用"监管困局"提供建议.