图的符号k-控制

设G（V,E）为一个图,k为任意的正整数且k不超过｜G｜,若有一个函数f：V｜1,－1｜满足：V中至少有k个点满足f[v]≥1,则称f为图G的一个符号k-控制函数,图G的符号k-控制数定义为γks^-11（G）=min{f（V）｜f为图G的一个符号k-控制}．给出了图的符号k-控制数的下界的一个改进的结论,并确定了轮图的符号k-控制数、     

模糊综合评价法在公司效能评估中的应用

企业效能的评估是任何一个经济体系中的核心问题,因为在企业的发展中,企业效能评估系统起着一种导向性的作用。在研究确定疏浚公司效能的各级评估指标体系的基础上,给出隶属度的确定方法,建立用模糊评价法评估疏浚公司综合效能的可行方法。疏浚公司综合效能评估既有定量指标也有定性指标,模糊评价法对定性指标的评价具有独特优势。     

农业机械化技术在农业发展中的作用及推广对策

近几年我国社会技术水平不断发展与进步,农业机械化技术也逐渐提升并逐步被运用到农业的发展中。但现今我国农业机械化技术还需要在农业发展中进行推广,促使农业经营人员对农业机械化技术的作用充分了解,并将其优势发挥出来,进而提高农业生产效率与质量,提高农业经济收益。以下内容重点对农业机械化技术在农业发展中的作用及推广对策开展探究,进而为农业发展奠定良好的基础。     

综合管廊U型盾构机械化施工工法研究与应用

为解决传统明挖法、矿山法、盾构法和顶管法在综合管廊施工中存在的不足和局限,根据国内管廊工程建设环境特点,通过分析传统管廊施工方法的优点和不足,结合装配式建筑的发展趋势,创新性地提出U型盾构机械化施工工法。该工法将明挖法开挖与在盾壳内完成主体预制拼装结构相结合,通过研制相应装备将传统固定支护结构转变为刚性可移动支护结构,实现了明挖法管廊施工的机械化、标准化和规范化。介绍U型盾构工法的原理、适用范围、工艺流程、操作要点和节点处理,对比U型盾构与传统明挖支护结构的受力特点和对周边环境的影响,分析U型盾构适用范围及其工法优势; 通过海口市椰海大道管廊试验,验证了该工法在明挖综合管廊施工中具有较高的进度优势、经济优势和推广应用价值; 最后探讨该工法在小曲线半径、矩形或U型断面工程以及明挖框架结构工程中的应用前景,以期为综合管廊及类似工程提供一种新的设计理念和施工工法。     

上海市高速公路高架系统功能与建设模式探讨

上海市高速公路存在四方面问题:地面路堤形式阻隔两侧地块横向联系;承担客货、省域市域等多种功能交通拥堵严重;进出立交节点匮乏为周边城市化地区服务功能差;影响区域路网完善。认为高速公路建设高架系统具备如下交通功能:打通横向道路、缝合城市空间,分离交通功能、缓解交通拥堵,优化节点布置、方便沿线地区对外出行,构筑复合通道、完善区域路网。给出了不同城市化水平下横向道路合理的间距要求以及适合的主线抬升方案,提出了高架高速主线+地面干路辅道、高架客运高速+地面客货高速、拓宽段高架+老路地面、地面局部高架+单侧地面辅道等4种高架系统的建设模式及其适用条件,给出了应用案例。能够较好地甄别高速公路高架化的功能需求及其相应的建设模式,为特大城市高速公路高架化改造提供借鉴。     

An application of the directional distance function with the number of accidents as an undesirable output to measure the technical efficiency of state road transport in India

By using the directional distance function (DDF) of data envelopment analysis (DEA), this study measures the technical efficiency of 37 Indian state road transport undertakings (SRTUs) for the year 2012–13. We employ the DDF as a tool for analyzing a joint production function with both desirable and undesirable outputs (i.e., the number of accidents). A comparison between the results with and without accidents shows that several SRTUs have experienced significant changes in their efficiency scores as well as in their rankings after accounting for the undesirable output. This indicates the importance of including the number of accidents – a safety standard – as representative of the undesirable output in computing the efficiency scores of SRTUs. The results of the Tobit model indicate that SRTUs with greater vehicle productivity are more efficient under both conventional DEA and DDF approaches. We also employed zero-truncated negative binomial model to assess the factors influencing the number of road accident experienced by the Indian SRTUs and found that the accident count was significantly influenced by fleet utilization and vehicle productivity.     

Dynamic pricing for managed lanes with multiple entrances and exits

Priced managed lanes are increasingly being used to better utilize the existing capacity of the roadway to relieve congestion and offer reliable travel time to road users. In this paper, we investigate the optimization problem for pricing managed lanes with multiple entrances and exits which seeks to maximize the revenue and minimize the total system travel time (TSTT) over a finite horizon. We propose a lane choice model where travelers make online decisions at each diverge point considering all routes on a managed lane network. We formulate the problem as a deterministic Markov decision process and solve it using the value function approximation (VFA) method for different initializations. We compare the performance of the toll policies predicted by the VFA method against the myopic revenue policy which maximizes the revenue only at the current timestep and two heuristic policies based on the measured densities on the managed and general purpose lanes (GPLs). We test the results on four different test networks. The primary findings from our research suggest the usefulness of the VFA method for determining dynamic tolls. The best-found objective value from the method at its termination is better than other heuristics for all test networks with average improvements in the objective ranging between 10% and 90% for revenue maximization and 0–27% for TSTT minimization. Certain VFA initializations obtain best-found toll profiles within first 5–50 iterations which warrants computational time savings. Our findings also indicate that the revenue-maximizing optimal policies follow the “jam-and-harvest” behavior where the GPLs are pushed towards congestion in the earlier time steps to generate higher revenue in the later time steps, a characteristic not observed for the policies minimizing TSTT.     

Forecasting short-term subway passenger flow under special events scenarios using multiscale radial basis function networks

Reliable and accurate short-term subway passenger flow prediction is important for passengers, transit operators, and public agencies. Traditional studies focus on regular demand forecasting and have inherent disadvantages in predicting passenger flows under special events scenarios. These special events may have a disruptive impact on public transportation systems, and should thus be given more attention for proactive management and timely information dissemination. This study proposes a novel multiscale radial basis function (MSRBF) network for forecasting the irregular fluctuation of subway passenger flows. This model is simplified using a matching pursuit orthogonal least squares algorithm through the selection of significant model terms to produce a parsimonious MSRBF model. Combined with transit smart card data, this approach not only exhibits superior predictive performance over prevailing computational intelligence methods for non-regular demand forecasting at least 30 min prior, but also leverages network knowledge to enhance prediction capability and pinpoint vulnerable subway stations for crowd control measures. Three empirical studies with special events in Beijing demonstrate that the proposed algorithm can effectively predict the emergence of passenger flow bursts.     

SS8电力机车模拟量接口通道

主要叙述了ＳＳ８电力机车微机控制系统中，模拟量输入／输出接口的特点，着重介绍了模拟量输入／输出接口板的功能组成，并从设计角度阐述了Ａ／Ｄ输入通道，Ｄ／Ａ输出通道的内部工作时序，最后给出了模拟量输入／输出接口板ＰＣＢ设计中几点体会。     

NIDDM患者红细胞免疫功能和C_3与CIC含量关系的研究

应用改良的红细胞酵母花环法测定了50例非胰岛素依赖型糖尿病(NIDDM)患者红细胞免疫功能,并与40例正常人的测定结果进行比较,结果表明:NIDDM患者红细胞免疫功能低于正常人(P<0.01)。本文还对红细胞免疫功能下降在NIDDM中的发病机理进行了初步探讨,并对红细胞免疫功能与循环免疫复合物(CIC)及补体C_3的关系也作了初步研究。