Dynamic demand estimation and prediction for traffic urban networks adopting new data sources

Nowadays, new mobility information can be derived from advanced traffic surveillance systems that collect updated traffic measurements, both in fixed locations and over specific corridors or paths. Such recent technological developments point to challenging and promising opportunities that academics and practitioners have only partially explored so far.The paper looks at some of these opportunities within the Dynamic Demand Estimation problem (DDEP). At first, data heterogeneity, accounting for different sets of data providing a wide spatial coverage, has been investigated for the benefit of off-line demand estimation. In an attempt to mimic the current urban networks monitoring, examples of complex real case applications are being reported where route travel times and route choice probabilities from probe vehicles are exploited together with common link traffic measurements.Subsequently, on-line detection of non-recurrent conditions is being recorded, adopting a sequential approach based on an extension of the Kalman Filter theory called Local Ensemble Transformed Kalman Filter (LETKF).Both the off-line and the on-line investigations adopt a simulation approach capable of capturing the highly nonlinear dependence between the travel demand and the traffic measurements through the use of dynamic traffic assignment models. Consequently, the possibility of using collected traffic information is enhanced, thus overcoming most of the limitations of current DDEP approaches found in the literature.     

State estimation in roll dynamics for commercial vehicles

Accurate lateral load transfer estimation plays an important role in improving the performance of the active rollover prevention system equipped in commercial vehicles. This estimation depends on the accurate prediction of roll angles for both the sprung and the unsprung subsystems. This paper proposes a novel computational method for roll-angle estimation in commercial vehicles employing sensors which are already used in a vehicle dynamic control system without additional expensive measurement units. The estimation strategy integrates two blocks. The first block contains a sliding-mode observer which is responsible for calculating the lateral tyre forces, while in the second block, the Kalman filter estimates the roll angles of the sprung mass and those of axles in the truck. The validation is conducted through MATLAB/TruckSim co-simulation. Based on the comparison between the estimated results and the simulation results from TruckSim, it can be concluded that the proposed estimation method has a promising tracking performance with low computational cost and high convergence speed. This approach enables a low-cost solution for the rollover prevention in commercial vehicles.     

Design of tyre force excitation for tyre–road friction estimation

Knowledge of the current tyre–road friction coefficient is essential for future autonomous vehicles. The environmental conditions, and the tyre–road friction in particular, determine both the braking distance and the maximum cornering velocity and thus set the boundaries for the vehicle. Tyre–road friction is difficult to estimate during normal driving due to low levels of tyre force excitation. This problem can be solved by using active tyre force excitation. A torque is added to one or several wheels in the purpose of estimating the tyre–road friction coefficient. Active tyre force excitation provides the opportunity to design the tyre force excitation freely. This study investigates how the tyre force should be applied to minimise the error of the tyre–road friction estimate. The performance of different excitation strategies was found to be dependent on both tyre model choice and noise level. Furthermore, the advantage with using tyre models with more parameters decreased when noise was added to the force and slip ratio.     

Power network parameter estimation method based on data mining technology

The parameter values which actually change with the circumstances, weather and load level etc.produce great effect to the result of state estimation. A new parameter estimation method based on data mining technology was proposed. The clustering method was used to classify the historical data in supervisory control and data acquisition (SCADA) database as several types. The data processing technology was impliedto treat the isolated point, missing data and yawp data in samples for classified groups. The measurement data which belong to each classification were introduced to the linear regression equation in order to gain the regression coefficient and actual parameters by the least square method. A practical system demonstrates the high correctness, reliability and strong practicability of the proposed method.     

幽门螺杆菌尿素通道蛋白基因UreI载体的构建、融合表达及纯化

目的构建幽门螺杆菌(H.pylori,Hp)尿素通道蛋白基因UreI的融合表达载体,并在E.coliBL21中表达,为进一步研究UreI的功能奠定基础。方法利用分子克隆技术以Hp DNA染色体为模板,扩增Hp UreI基因片段,将目的基因UreI与载体pET32a( )分别经kpnⅠ和HindⅢ双酶切,纯化,连接。筛选阳性重组载体,转化大肠杆菌BL21,以IPTG诱导表达pET32a( )/UreI融合蛋白。表达产物经Ni-NTA琼脂糖树脂纯化后,用SDS-PAGE及Western blot分析。结果经酶切、测序分析表明,插入的基因片段为Hp UreI编码基因,由585 bp组成,与GenBank相应菌株HP AM417 609序列完全一致,无碱基突变。经SDS-PAGE分析显示重组质粒pET32a( )/UreI在原核细胞中得到了高效融合表达,其重组融合蛋白分子量为130 ku,经Ni-NTA琼脂糖树脂纯化后,其纯度达95%以上,Western blot分析显示,该重组融合蛋白可被6-His鼠抗单克隆抗体所识别,具有良好的反应原性。结论成功地克隆和构建了原核表达载体pET32a( )/UreI,并在原核细胞中得到了高效融合表达。     

基于层次分析法的区间估计的车站能力查定误差因子分析研究

本文归纳总结了车站能力查定计算过程中存在的多种影响因素,深入分析了其产生原因和不可避免性。然后利用层次分析法的区间估计方法计算得出各种误差因子对计算结果的影响权重大小,并对比不同误差因子的权重区间,筛选出强误差因子,剔除弱误差因子,为精确计算车站能力值提供依据。     

考虑多人相互影响的舰船通道最短路径规划

将时间维引入既定舰船通道网络,把考虑多人相互影响的动态最优路径规划问题转化为时间依赖网络中的最优路径搜索问题。首先,论文的算法为所有人员随机生成走行路径,为了预测网络中的弧(路段)的走行时间,按人员速度从慢到快的顺序依次计算并记录人员到达路径中的各路段首节点的时刻,先记录到的人员将成为后记录到的人员的动态障碍。然后,将遗传算法与网络中弧的走行时间预测方法相结合,借助遗传算法的个体多样性天然地解决了人员走行任意性问题,因而获得了全局动态最优路径算法,并仿真计算了两人以及三人的最短时间路径;经与不考虑人员间相互影响时获得的最优路径相比较,论文的算法获得了人员遇到障碍时(或跟行或绕行)的最优走行路径。最后,借助时间依赖网络中的最优路径充要条件定理,说明了算法的有效性。     

田湾核电站扩建工程取水明渠导流堤优化设计

取水工程为核电厂重要构筑物,按照较高的核电标准设计往往断面较大,在保证取水安全的前提下,分析不同工程的使用要求,有针对性的的进行优化设计,可降低工程造价。以田湾核电取水工程为例,分析优化设计过程,供类似工程参考。     

护底软体排破坏机理及应对措施

软体排边缘床面易受不利水流冲刷下切,当冲刷下切强度超过排体变形能力时,软体排排边会出现变形破坏。分析了护底软体排变形破坏的主要影响因素:水流条件、河床组成、软体排自身结构、余排宽度及施工工艺等。探讨了护底软体排破坏的力学机理。提出在排边一定范围内抛投一定密度的扭双工字型透水框架,能削减排边近底层的流速及紊动强度进而减弱或抑制排边冲刷,从而维持软体排结构安全及坝体稳定的应对措施。     

长江口北港重大工程对河势演变的影响

北港是长江口的二级入海汊道。近年来,北港修建了诸多水利工程,如南北港分流口固沙工程、青草沙围水工程和横沙东滩促淤圈围工程等,它们对北港河势有一定的稳定作用,但在流域来沙锐减的背景下,也带来一些新的潜在问题。分流口固沙工程的建设一定程度上增强了新桥通道南侧沙体的稳定性,但与此同时,由于扁担沙尾部继续向新桥通道挤压推移,导致北港分流比减小。青草沙水库建设后,北港上段继续冲刷,由于横沙通道的不断发展,致使北港主槽曲率进一步增大。北港拦门沙河段的淤积和横沙东滩的促淤圈围工程促使了北港北汊的发展,但该汊道中增强的涨潮流对青草沙水库"蓄淡避咸"产生了一定的影响。