Location of bus garages

The location of bus garages is a complex issue that has received recent attention in the literature. Given a bus system, the number of bus garages and their locations depend on garage cost, deadheading cost and environmental impacts. An approximate analytical model is used to determine the number of bus garages that minimizes the above costs. The concept of a slowly varying density of bus-route origins (hence deadheads) per unit area is used to model deadheading costs. The increased deadheading caused by breakdowns and accidents is also considered. The garage cost is modeled as a function of the number of buses stored. A closed-form solution is obtained for the optimal density of garages, when the garage cost function is linear. The actual locations of garages and the allocations of buses to the garages are found using a discrete space location-allocation model formulated so as to consider the environmental impact associated with buses deadheading through populated neighborhoods.     

Influence of vehicular traffic on urban air quality – A case study of Hyderabad,India

In the present study, impact of vehicular traffic emissions on black carbon aerosol mass concentration, trace gases and ground reaching solar radiation were analyzed during nationwide truck strike of 5–12 January, 2009 over urban environment of Hyderabad, India. A significant reduction of about 57%, 60%, 40% and 50% was observed in black carbon, particulate matter, carbon monoxide and ozone respectively during nationwide truck strike period. Results of the study are important for source apportionment of pollutants as the strike created natural laboratory for studying the impact of diesel operated trucks on urban air quality.     

Development of hot stamped center pillar using form die with channel type indirect blank holder

The hot stamping process has been used in the automotive industry to reduce the weight of the body-in-white and to increase passenger safety via improved crashworthiness. However, defects such as fracture and wrinkle occur when hot stamping is performed using a conventional drawing or forming method. In this study, a channel-type indirect blank holder (CIBH) is proposed to develop a high-strength center pillar in form-type hot stamping, so that the aforementioned drawbacks are overcome. This type of blank holder plays an important role in reducing severe wrinkling at the flange; such wrinkling leads to folding after the completion of form-type hot-stamping. First, we investigated the effect of the channel shape on the indirect blank holding force by using a simplified two-dimensional plane-strain stamping process. Second, we selected the slope angle and corner radius of the channel as the main shape parameters by finite element analysis and artificial neural network (ANN). It is known that fracture at the hot formed wall and wrinkle at the flange are significantly affected by the slope angle of the channel, and the appropriate value for eliminating fracture and wrinkle is determined to be 99°. By performing hot stamping using a form die with the selected channel, we can manufacture a high-strength center pillar without wrinkle and fracture.     

Influence of compliance for an elastokinematic model of a proposed rear suspension

The research is carried out to improve passenger’s comfort to increase the vehicles stability in dynamic conditions. The literature available in the automotive engineering considers different topics for studying suspensions. An example represents mechanisms structure and analysis (synthesis, kinematics, and dynamics) under various operating conditions. These aspects have been approached before analytically, numerical. The current paper studies the influence of the lateral force on the contact patch of the wheel and the corresponding variations of vehicle stability parameters, such as camber angle and wheel rear track. The study is performed for a newer innovative rear suspensions mechanism which does not have a wheel track and camber angle variation, relative to the chassis, when the suspension components was considered rigid. A numerical solution is obtained through a virtual model on several commercial codes: MSC Adams, Patran, Nastran. Concerning the analysed parametes, their variation increases as the applied force is increased. Moreover, the largest variation corresponds to the case were elastic bushings and deformable links are considered.     

Calculation of Transient Stress Field During Laser Transformation Hardening Process

IntroductionHighpowerCOzlaserssdsetransformationhardeningtechniquehasbeensuccessfullyusedinindusnyforWYears.BecausethetemPeratUrefleldislocalizedinmaterialdurllglasertransfonnationhMngProcess,highthermstrCsswillgenerateinmatgrialduringlasertfansformationhardeningProcess.Therisalsohighresidualstressinmaterial,bothintCnsionandcomPression['-'].ComPressresidualstressishelptoincreasethefatigueldrimeofthelasertreatedmaterial,butthetensilestresswillshortenthefatiguelifetmeofthelasertreatedmator…     

Multiaxial stress creep rupture mechanisms of AZ31 magnesium alloy

The maximum principal stresses, von Mises effective stresses and principal facet stresses at the time of creep rupture were compared in uniaxial, biaxial, and triaxial stress states for AZ31 magnesium alloy. The creep rupture of this alloy was experimentally controlled by cavitation, which was the result of a low damage tolerance, λ. Creep deformation could be correlated with the von Mises effective stress parameter. The failure-mechanism control parameter governing the stress state coincided with the experimental results of the rupture of the materials under multiaxial stress states. Finally, the theoretical prediction based on constrained cavity growth and continuous nucleation agreed with the experimental rupture data to within a factor of three.     

Effect of rear slant angle on vehicle crosswind stability simulation on a simplified car model

It is important to know the effect of the aerodynamic forces and moments on driving stability because it is responsible for the excitation and influences the response of the vehicle. The purpose of this paper is to study the effect of rear slant angle of a surface vehicle on crosswind sensitivity for stability analysis. The vehicle mathematical model used to conduct a dynamic simulation was based on a simple reduced order lateral dynamics of sideslip and yaw rate motion coupled with aerodynamics model. The intention here is to compare the effect of rear slant angles response to crosswind and to rank the crosswind sensitivity ratings. The aerodynamic loads are defined as the function of the aerodynamic derivatives from the static wind tunnel tests. Result shows a 20° rear slant angle demonstrates the highest rating of crosswind sensitivity, while zero degree slant exhibits the least.     

Activity patterns,time use,and travel of millennials: a generation in transition?

Millennials, defined in this study as those born between 1979 and 2000, became the largest population segment in the United States in 2015. Compared to recent previous generations, they have been found to travel less, own fewer cars, have lower driver’s licensure rates, and use alternative modes more. But to what extent will these differences in behaviour persist as millennials move through various phases of the lifecycle? To address this question, this paper presents the results of a longitudinal analysis of the 2003–2013 American Time Use Survey data series. In early adulthood, younger millennials (born 1988–1994) are found to spend significantly more time in-home than older millennials (born 1979–1985), which indicates that there are substantial differences in activity-time use patterns across generations in early adulthood. Older millennials are, however, showing activity-time use patterns similar to their prior generation counterparts as they age, although some differences – particularly in time spent as a car driver – persist. Millennials appear to exhibit a lag in adopting the activity patterns of predecessor generations due to delayed lifecycle milestones (e.g. completing their education, getting jobs, marrying, and having children) and lingering effects of the economic recession, suggesting that travel demand will resume growth in the future.     

One city,three models: comparison of land‐use/transport policy simulation models for Dortmund

The paper reports on simulation experiments conducted by the International Study Group on Land‐Use/Transport Interaction (ISGLUTI) for the metropolitan region of Dortmund in the Federal Republic of Germany. Three land‐use/transport simulation models were applied to the Dortmund region: the DORTMUND model developed at the University of Dortmund, the LILT model being used at University College London and the MEPLAN package developed by Marcial Echenique & Partners in Cambridge. The three models are briefly characterized and their ex‐post forecasts are compared with the actual development of the region. The final section of the paper compares how the three models respond to a common set of assumptions and policies from the fields of land‐use control, traffic management and transport investment. The differences in model response give insights into the validity of the theoretical foundations and internal structure of the models.