Pole location control design of an active suspension system with uncertain parameters

This paper addresses the problem of robust control design for an active suspension quarter-car model by means of state feedback gains. Specifically, the design of controllers that assure robust pole location of the closed-loop system inside a circular region on the left-hand side of complex plane is investigated. Three sufficient conditions for the existence of a robust stabilizing state feedback gain are presented as linear matrix inequalities: (i) the quadratic stability based gain; (ii) a recently published condition that uses an augmented space and has been here modified to cope with the pole location specification; (iii) a condition that uses an extended number of equations and yields a parameter-dependent state feedback gain. Unlike other parameter-dependent strategies, neither extensive gridding nor approximations are needed. In the suspension model, the sprung mass, the damper coefficient and the spring constant are considered as uncertain parameters belonging to a known interval (polytope type uncertainty). It is shown that the parameter-dependent gain proposed allows one to impose the closed-loop system pole locations that in some situations cannot be obtained with constant feedback gains.     

Developing a chaotic pattern of dynamic Hazmat routing problem

The present paper proposes an iterative procedure based on chaos theory on dynamic risk definition to determine the best route for transporting hazardous materials (Hazmat). In the case of possible natural disasters, the safety of roads may be seriously affected. So the main objective of this paper is to simultaneously improve the travel time and risk to satisfy the local and national authorities in the transportation network. Based on the proposed procedure, four important risk components including accident information, population, environment, and infrastructure aspects have been presented under linguistic variables. Furthermore, the extent analysis method was utilized to convert them to crisp values. To apply the proposed procedure, a road network that consists of fifty nine nodes and eighty two-way edges with a pre-specified affected area has been considered. The results indicate that applying the dynamic risk is more appropriate than having a constant risk. The application of the proposed model indicates that, while chaotic variables depend on the initial conditions, the most frequent path will remain independent. The points that would help authorities to come to the better decision when they are dealing with Hazmat transportation route selection.     

The Added Value of Accounting For Users’ Flexibility and Information on the Potential of a Station-Based One-Way Car-Sharing System: An Application in Lisbon,Portugal

Car-sharing systems are an alternative to private transportation whereby a person may use an automobile without having to own the vehicle. The classical systems in Europe are organized in stations scattered around the city where a person may pick up a vehicle and afterward return it to the same station (round trip). Allowing a person to drop off the vehicle at any station, called one-way system, poses a significant logistics problem because it creates a significant stock imbalance at the stations, which means that there will be times when users will not have a vehicle available for their trip. Previous mathematical programming formulations have tried to overcome this limitation by optimizing trip selection and station location in a city in order to capture the best trips for balancing the system. But there was one main limitation: The users were assumed to be inflexible with respect to their choice of a station, and held to use only the one closest to their origin and destination. If the user is willing to use the second or even the third closest station the user could benefit from using real-time information on vehicle stocks at each station and be able to select the one with available capacity. In this article we extend a previous model for trip selection and station location that takes that aspect into account by considering more vehicle pick-up and drop-off station options and then apply it to a trip origin–destination matrix from the Lisbon region in Portugal. Through the extended formulation we were able to conclude that user flexibility allied with having information on vehicle stocks increases the profit of the company, as people will go directly to a station with a vehicle available, thus making the use of the fleet more efficient. Observing the size of the stations resulting from the model, we also concluded that the effect of information is enhanced by large car-sharing systems consisting of many small stations.     

Car sharing in Norwegian urban areas: Examining interest,intention and the decision to enrol

This article’s objective is to investigate the effects of sociodemographic and residential built environments, directly and indirectly through personality traits, attitudes and car ownership, on willingness to use car sharing in the case of Norway. This is done by examining multiple dimensions of the adoption process: the stated general interest and intention to participate in car sharing among non-members, as well as the decision to enrol as a car sharing user by comparing members to non-members. In this study, we analyse web survey data from 2414 residents from urban areas in Norway, using three structural equation models. Our findings indicate that the adoption of car sharing is complexly related to car ownership, with a noteworthy discrepancy indicating greater car sharing interest, but lower car sharing membership rates among car owners. We also find that environmental concerns exert a clear positive effect on all three dimensions of the adoption process. Being careful with money is linked negatively to interest and intention to participate, while being sociable and agreeable exerts no effect. Car sharers’ sociodemographic profiles are typically that of early adopters, but many of the effects, especially on interest, are mediated by car ownership, environmental consciousness and/or being careful with money, rather than directly on the sociodemographic profiles. Finally, we find car sharing to be more prominent in denser areas, but we did not discover a clear connection with access to public transport.     

旬邑至汉中铁路建设方案研究

为构建"陕煤入川渝"通道,以旬邑至汉中铁路为研究对象,对其建设方案进行系统研究。首先,基于功能定位、运量预测、主要技术标准等要素,综合考虑主要经济据点及重点控制工程分布情况,分段对线路走向方案进行论证研究。其次,从工程地质、技术条件、环境保护、规划协调等方面系统考虑,采用RT-TOPSIS模型对各分段线路方案进行综合决策,生成各分段最优线路方案。最后,以综合决策结果为基础,对整体线路具体走向进行阐述说明。     

Traffic accident risk perception among drivers: a latent variable approach

ABSTRACT

Governments require decision tools to deal with road traffic accidents, a pandemic resulting in millions of deaths around the world. Evidence shows that human factors are one of the major causes of road accidents, and there is much interest in identifying variables that may have an impact on drivers’ perception of risk. To this aim, we design a stated choice experiment with eight hypothetical driving scenarios considering attributes that have been strongly associated with increased accident risks: (i) driving speed, (ii) driving the wrong way in a one-way street, (iii) overtaking on a bend, and (iv) driving under the influence of alcohol or drugs. Data from a sample of survey respondents are used to estimate a hybrid discrete choice model incorporating two latent variables, Driver Concentration and Safe Driving. Our results may contribute to the design of public policies geared to prevent accidents by encouraging safer driving behaviour.     

Influence of hydrography on phytoplankton distribution in the Amundsen and Ross Seas, Antarctica

The phytoplankton of the Ross Sea have been intensively studied, in contrast to that of the Amundsen Sea. This study focused on understanding the environmental variables that influence the spatial patterns of assemblages during late summer, 2007, and late spring-early summer, 2008 in the Amundsen and Ross Seas. Blooms of the prymnesiophyte Phaeocystis antarctica, and the silicoflagellate Dictyocha speculum occurred in the southwestern to eastern parts of the Ross Sea, respectively, whereas diatoms dominated in southeastern Ross and the Amundsen Sea. Shallow mixed layers supported the growth of diatoms, but were not the only factor required for diatom bloom development. Modified Circumpolar Deep Water intruded into the subsurface waters (< 200 m) in the southwestern Ross Sea during February 2007, and possibly favored the formation of P. antarctica blooms. Photosynthetic quantum yield data suggest that blooms from the southwestern Ross Sea were approaching stress during January 2008, likely due to iron limitation, in contrast to blooms close to the ice edge in the Amundsen Sea, where iron may be more available to the phytoplankton. A detailed comparison between the Amundsen and Ross Seas may allow a greater understanding of the environmental-induced impacts on phytoplankton distribution and regional biogeochemical cycles.     

多因素作用下隧道衬砌内力随时间变化规律

针对隧道初期支护和二次衬砌施作间隔时间短的工程特点,为掌握类似条件下衬砌受力变化的规律,分析二次衬砌钢筋轴力监测数据及相应的施工工况,研究隧道开挖、围岩蠕变、隧道衬砌刚度等因素对二次衬砌钢筋轴力变化的影响,如二次衬砌钢筋轴力变化曲线可分为2个明显的双曲线变化阶段：第一阶段主要受隧道开挖和隧道衬砌刚度的影响,围岩蠕变明显,在其作用下二次衬砌钢筋轴力明显增加,且轴力变化至少在1年后才趋于稳定,第一阶段大约持续33d,此阶段隧道衬砌刚度基本形成,而后二次衬砌钢筋变化进入第二阶段;第二阶段变化主要受围岩蠕变的影响。