学生食堂优化管理的数学模型

从学生食堂的设备及场所、物资的储存与购入、工作人员的管理及就餐者对食堂的要求这4个方面描述了各自对学生食堂管理的影响,得出了评估学生食堂优劣的一般公式Y=n∑i=1ωixi,并着重解决了学生就餐排队等待时间太长的问题,分析了该等待问题在排队论中所属的模型,解决了该课题要研究的问题的一般情况和个别案例,确定了各参数之间的关系.通过分析,得出了最优排队模型、费用模型及服务台数,并证明了最优模型的一般性.     

APL-based flexibility analysis of manufacturing grid

With the characteristics of diversity, randomness, concurrency and decomposability, tasks in manufacturing field are very complicated, and so manufacturing grid(MG)should have considerable flexibility to deal with this problem. With the definition of node and arc, MG structure is converted into a small-world network. Given construction cost constraint, the problem of shortest task waiting time is transformed into the constrained optimization problem, and a corresponding flexibility analysis model based on average path length(APL)is proposed, and the premise of arc-length and node-distance are defined. The results of application example show that the analysis model is effective.     

新疆高校爱国主义教育的侧重点和有效途径

爱国主义是一个历史范畴,在社会发展的不同阶段、不同历史时期有不同的内涵。其具体内容是随着国家的历史条件和历史阶段的变化而发展变化的。马克思主义“五观”教育、新疆历史和区情教育、民族团结和“四个认同”教育、维护祖国统一反对民族分裂和非法宗教活动的教育是新疆高校实施爱国主义教育的侧重点。针对这一特点,新疆高校必须采取一些措施、寻求新的途径和方法进行有国主义教育。     

网络资源命名及用户命名行为的分析

网络资源是指通过互联网传播共享、以文件目录为主要存储组织结构的内容,如书、讲义、音乐等.每个资源的内容具有完整独立性.它们是数字图书馆、教学资源库、专业内容库藏的重要组成.网络资源的一大特点是命名模式不规范,给检索利用带来极大不便.本文以2003～2006年间搜集的61万文件构成的16 284个网络资源为对象,用统计的方法考察网络资源命名特点及其中体现的用户命名习惯.包括资源及其内部子目录、文件的名字长度分布,字符类型熵、常用符号、高频片段模式、语义类型等,并分析无序命名中蕴含的用户命名习惯.本文的意义一方面有助于从混乱命名中净化和提取对检索查询有用的信息,另一方面有助于揭示网络用户参与海量网络资源共享的行为习惯.     

中国大学生龙舟男子500m直道途中坐姿划桨技术的运动学分析

对2006年首届、2009年第三届、2011年第四届中国大学生龙舟锦标赛男子直道500m前3名运动队途中划桨三次现场双机同步二维平面拍摄,运用SIMImotion7．50生物力学解析系统解析,拟揭示途中划桨技术的运动学特征。结果表明：抓水阶段是动力阶段,该阶段桨的入水角度小,抓水猛、稳、准,桨面与舟前进法线的夹角减小;拉水阶段的动作特点是拉桨快而深,划距增大,该阶段需要调整合理浆频和划距;提桨要巧,动作要快,幅度要小;外摆阶段空中划摆快,举桨、撑桨幅度增大;举插阶段桨摆动角速度变小,舟速从最小舟速开始增加;整个途中划姿不变,桨频为中桨频;人体在垂直方向的变化很小,主要为水平方向上近匀速的运动,平均速度为6．02m／s,T抓水：T拉水：Tl提浆：T外摆：T举插＝5：6：4：6：4,节奏分明,周期0．71s。旨在为龙舟划桨技术改进提供参考。     

The nature of force depression and force enhancement in skeletal muscle contraction

Here, we review the history-dependent phenomena associated with muscle force production. Specifically, the depression of the steady-state isometric force following muscle shortening, and the enhancement of the steady-state isometric force following muscle stretching are discussed. First, we describe the observations that have been made experimentally, then we introduce the primary proposed mechanisms for force depression and force enhancement. Next, in view of the available results, we critically evaluate specific hypotheses based on these mechanisms. Finally, we recommend further discussion about some of the proposed mechanisms.     

Forefoot running requires shorter gastrocnemius fascicle length than rearfoot running

ABSTRACT

This study aimed to investigate the influence of foot strike patterns on the behaviour of the triceps surae muscle-tendon unit, including the Achilles tendon whose length nearly corresponds to force of the triceps surae, and the medial gastrocnemius muscle (MG) during running. Seven male volunteers ran with forefoot and rearfoot strikes at 10, 14 and 18 km h^?1 on a treadmill. The MG fascicle length was measured using ultrasonography. The in vivo length of the curved Achilles tendon was quantified by combining ultrasonography with optical motion capture of reflective markers on the right lower limb and an ultrasound probe. The forefoot strike resulted in a significantly shorter MG fascicle length at the initial contact, at Achilles tendon peak elongation, and at toe-off, than the rearfoot strike. The Achilles tendon length at initial contact was greater during the forefoot strike than during the rearfoot strike at 18 km h^?1, while its peak elongation was not significantly different during forefoot and rearfoot running. These results indicate that the MG, with a shorter length during forefoot running, manages to address demands for a similar peak force of the triceps surae than during rearfoot running.     

Ball launch conditions for skilled golfers using drivers of different lengths in an indoor testing facility

Abstract

The displacement of the golf ball struck by a driving club is affected by several player characteristics and equipment parameters and their interrelationships. Some modelling and simulation studies have shown a relationship between shaft length and clubhead speed, supported by a few experimental studies. The aim of the present study was to examine the relationship between driver length and ball launch conditions in an indoor test facility using a ball launch monitor. Nine males considered to be skilled golfers participated in the study. Four driving clubs of total length 117, 119, 124, and 132 cm were assembled from commercially available components and were used to strike golf shots while initial ball velocity, backspin rate, and launch angles were measured. Statistical analysis identified a significant difference in initial launch speed due to club length, a significant difference between participants, but no difference between the trials for a given golfer. A positive trend was noted between backspin and launch angle for all four clubs, and significant inverse associations between initial launch speed and backspin rate and launch angle. However, the combined launch conditions associated with increasing length were not considered optimal, with uncontrolled swingweight and moment of inertia effects considered to be limiting factors.     

Improved sentence retrieval using local context and sentence length

In this paper we propose improved variants of the sentence retrieval method TF–ISF (a TF–IDF or Term Frequency–Inverse Document Frequency variant for sentence retrieval). The improvement is achieved by using context consisting of neighboring sentences and at the same time promoting the retrieval of longer sentences. We thoroughly compare new modified TF–ISF methods to the TF–ISF baseline, to an earlier attempt to include context into TF–ISF named tfmix and to a language modeling based method that uses context and promoting retrieval of long sentences named 3MMPDS. Experimental results show that the TF–ISF method can be improved using local context. Results also show that the TF–ISF method can be improved by promoting the retrieval of longer sentences. Finally we show that the best results are achieved when combining both modifications. All new methods (TF–ISF variants) also show statistically significant better results than the other tested methods.     

共焦椭圆柱的电容和电场

用变换函数授讨论共焦椭圆柱的电容和电场。