Bridge expansion joint in road transition curve: effects assessment on heavy vehicles

Properly-designed road surfaces provide a durable surface on which traffic can pass smoothly and safely. In fact, the main causes that determine the structural decay of the pavement and its parts are the traffic loads. These repeated actions can create undesirable unevennesses on the road surface, which induce vertical accelerations on vehicles, up to hindering contact between pavement and tire, with dangerous consequences on traffic safety. The dynamic actions transmitted by the vehicles depend on these irregularities: often, a bridge expansion joint (BEJ), introducing a necessary discontinuity between different materials, determines from the beginning a geometric irregularity in the running surface. Besides, some structural conditions could emphasize the problem (e.g., local cracking due to the settlement of the subgrade near the abutment or the discontinuity of stiffness due to the presence of different materials). When the BEJ is located in a transition curve, an inevitable vertical irregularity between road and joint can reach values of some centimeters, with serious consequences for the road safety. This paper deals with the analysis of a case study of a BEJ. Several test surveys were performed in order to fully characterize the effects on both vehicles and pavement. The three-dimensional representation of the pavement surface and the acceleration measurements on a heavy test vehicle were performed to analyze the joint behavior under traffic. Finally, a finite element model was implemented to evaluate the stress contribution on vehicle components induced by the vertical irregularities

Tyre curve estimation in slip-controlled braking

Progress in reducing actuator delays in pneumatic brake systems creates an opportunity for advanced anti-lock braking algorithms to be used on heavy goods vehicles. However, these algorithms require knowledge of variables that are impractical to measure directly. This paper introduces a braking force observer and road surface identification algorithms to support a sliding-mode slip controller for air-braked heavy vehicles. Both the force observer and the slip controller are shown to operate robustly under a variety of conditions in quarter-car simulations. A non-linear least-squares algorithm was found to be capable of performing regressions on all the parameters of the tyre model from the University of Michigan Transportation Research Institute when used ‘in the loop’ with the controller and the observer. A recursive least-squares algorithm that is less computationally expensive than the non-linear algorithm was also investigated but gave only reasonable estimates of the tyre model parameters on high-friction smooth roads. The authors would like to thank the members of the Cambridge Vehicle Dynamics Consortium (CVDC), and the Gates Cambridge Trust for their parts in funding this work.This is the author accepted manuscript. The final version is available from Sage via http://dx.doi.org/10.1177/095440701558593

Field Testing of a Cyclist Collision Avoidance System for Heavy Goods Vehicles

This research focused on preventing collisions between cyclists and heavy goods vehicles (HGVs). A collision avoidance system, designed to avoid side-to-side collisions between HGVs and cyclists, is proposed. The cyclist’s motion relative to the HGV is measured with an array of ultrasonic sensors. The detected distances from ultrasonic sensors are processed in real time to construct a smooth trajectory for the cyclist. The controller assumes constant acceleration and constant yaw rate for both the HGV and the cyclist and extrapolates the relative motion forward in time. The HGVs' brakes are engaged if a collision is predicted. A prototype system was built and fitted onto a test truck. The proposed collision avoidance system was tested in real time and proved to be effective within certain speed ranges.The authors thank the support of the Cambridge Vehicle Dynamics Consortium, whose member at the time of writing are: Anthony Best Dynamics, Camcon, Cambridge University, Denby Transport, Firestone Goodyear, Haldex, Laing O’Rourke, MIRA, SDC Trailers, SIMPACK, Tridec, Tinsley Bridge, Wincanton and Volvo Trucks. Special thanks go to Anthony Best Dynamics and Laing O'Rourke for proving essential testing equipment. Thanks also go to Dr Richard Roebuck, Dr Leon Henderson and Ms Amy Rimmer for their assistance with the testing. The authors also would like to thanks China Scholarship Council and Cambridge Trusts for their contribution to the research.This is the author accepted manuscript. The final version is available from IEEE via http://dx.doi.org/10.1109/TVT.2016.253880

Sideslip estimation for articulated heavy vehicles at the limits of adhesion

Various active safety systems proposed for articulated heavy goods vehicles (HGVs) require an accurate estimate of vehicle sideslip angle. However in contrast to passenger cars, there has been minimal published research on sideslip estimation for articulated HGVs. State-of-the-art observers, which rely on linear vehicle models, perform poorly when manoeuvring near the limits of tyre adhesion. This paper investigates three nonlinear Kalman filters (KFs) for estimating the tractor sideslip angle of a tractor–semitrailer. These are compared to the current state-of-the-art, through computer simulations and vehicle test data. An unscented KF using a 5 degrees-of-freedom single-track vehicle model with linear adaptive tyres is found to substantially outperform the state-of-the-art linear KF across a range of test manoeuvres on different surfaces, both at constant speed and during emergency braking. Robustness of the observer to parameter uncertainty is also demonstrated.Engineering and Physical Sciences Research Council, Cambridge Vehicle Dynamics Consortiu

Theory and practice of reversing control on multiply-articulated vehicles

A path-tracking controller is presented for automating the reversing of multiply-articulated vehicles. This uses a state feedback approach and steers the wheels of the front axle to ensure that the rearmost vehicle unit tracks a specified path. Linear closed-loop analysis is performed and shows that the controller is stable for vehicles with up to six trailers. The controller is implemented on three full-size experimental heavy vehicles: a ‘tractor–semitrailer’, a ‘B-double’ vehicle and a ‘B-triple’ vehicle, which have one trailer, two trailers and three trailers respectively. Experimental results are presented and the controller performance is evaluated. All test vehicles were able to track the paths to within 400 mm of the desired path. This research was funded by the Engineering and Physical Sciences Research Council (EPSRC) and Volvo Trucks through an Industrial CASE award. The authors would like to acknowledge Leo Laine and Carl-Johan Hoel from Volvo Trucks for their collaboration and contributions to the research.This is the author accepted manuscript. The final version is available from Sage via http://dx.doi.org/10.1177/095440701559691

Full-scale testing of a novel slip control braking system for heavy vehicles

This paper summarises the measured emergency braking performance of a tri-axle heavy goods vehicle semitrailer fitted with a novel pneumatic slip control braking system developed by the Cambridge Vehicle Dynamics Consortium. Straight-line braking tests were carried out from 40 km/h in order to compare a commercially electro-pneumatic available anti-lock braking system and the Cambridge Vehicle Dynamics Consortium system, which has bi-stable valves coupled with a sliding-mode slip controller. On average, the Cambridge Vehicle Dynamics Consortium system reduced the stopping distance and the air use by 15% and 22% respectively compared with those for the conventional anti-lock braking system. The most significant improvements were seen on a wet basalt-tile surface (with similar friction properties to ice) where the stopping distance and the air use were improved by 17% and 30% respectively. A third performance metric, namely the mean absolute slip error, is introduced to quantify the ability of each braking system to track a wheel slip demand. Using this metric, the bi-stable valve system is shown to improve the wheel slip demand tracking by 62% compared with that of the conventional anti-lock braking system. This improvement potentially allows more accurate control of the wheel forces during extreme manoeuvres, providing scope for the future development of advanced stability control systems. This work was supported by Haldex Brake Products Ltd, the New Zealand Tertiary Education Commission and the Cambridge Vehicle Dynamics Consortium (CVDC).This is the author accepted manuscript. The final version is available from Sage via http://dx.doi.org/10.1177/095440701560480

Relationship between heavy vehicle speed limit and fleet fuel consumption on minor roads

This paper investigates the traffic-related effects of a proposal to increase the speed limit from 40 mile/h to 50 mile/h, for heavy goods vehicles greater than 7.5 tonnes, on single carriageway roads. A ‘microscopic’ single carriageway traffic simulation is developed by combining the ‘enhanced intelligent driver model’ with a single carriageway gap-acceptance passing model. Fuel consumption estimates are made using engine characteristic maps and a ‘fuel optimal’ gear selection scheme, where vehicle trajectories from the traffic simulations are taken as input drive-cycles. Traffic congestion and fleet fuel consumption are specifically addressed, though implications regarding passing behaviour and traffic safety are also noted. Results indicate that the proposed 50 mile/h heavy goods vehicles speed limit would reduce traffic congestion by over 37% and increase fleet fuel consumption by approximately 0.5 L/100 km. The authors would like to thank Justin Bishop and Niall Martin of Cambridge University Engineering Department for providing valuable data. The authors would also like to thank Rachael Dillon of Freight Transport Association for suggesting the project. This work was supported in part by the Centre for Sustainable Road Freight (SRF) and the Engineering and Physical Sciences Research Council (EPSRC) through Grant Ref EP/K00915X/1. At the time of writing, the members of the SRF were: Coca-Cola Enterprises, Denby Transport, DHL, Freight Transport Association, Haldex Brake Products, Goodyear Tires, John Lewis/Waitrose, Laing O’Rourke, Optrak, SDC Trailers, Tesco, Volvo Trucks, Warburtons, Wincanton.This is the accepted manuscript for a paper published in the Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, DOI: 10.1177/0954406215573038

The organization and management of nuclear power plants

The explanation of aggregate and sectoral investment behavior has been one of the less successful endeavors in empirical economics. Existing econometric models have had little success in explaining or predicting investment spending. This may be because most such models fail to account for the irreversibility of most investment spending. With irreversibility, changes in the riskiness of future cash flows or interest rates should in theory dramatically affect the decision to invest - more so than, say, a change in the levels of interest rates. Here I survey some of the empirical support for this proposition, and discuss the implications for investment modelling.Nuclear power plants are a controversial technology. The future of the industry depends on the ability to manage efficiently and safely, and to effectively manage organizational change as new technologies and practices are introduced and disseminated. This paper provides a conceptual framework and discussion of the management and organization of nuclear power plants around three questions: (1) How should nuclear power plants be organized and managed to ensure that they are operated most safely and efficiently? (2) What does an understanding of the organization and management of nuclear power plants tell us about how they change or resist change? and (3) What indicators or measures of various characteristics and processes of nuclear power plants are needed in order to address the above questions? We review existing literature on the organization and management of nuclear power plants, and suggest how we would structure a research project to address the above questions.Supported by the Center for Energy Policy Research at M.I.T

Materials Selection for Aerospace Systems

A systematic design-oriented, five-step approach to material selection is described: 1) establishing design requirements, 2) material screening, 3) ranking, 4) researching specific candidates and 5) applying specific cultural constraints to the selection process. At the core of this approach is the definition performance indices (i.e., particular combinations of material properties that embody the performance of a given component) in conjunction with material property charts. These material selection charts, which plot one property against another, are introduced and shown to provide a powerful graphical environment wherein one can apply and analyze quantitative selection criteria, such as those captured in performance indices, and make trade-offs between conflicting objectives. Finding a material with a high value of these indices maximizes the performance of the component. Two specific examples pertaining to aerospace (engine blades and pressure vessels) are examined, both at room temperature and elevated temperature (where time-dependent effects are important) to demonstrate the methodology. The discussion then turns to engineered/hybrid materials and how these can be effectively tailored to fill in holes in the material property space, so as to enable innovation and increases in performance as compared to monolithic materials. Finally, a brief discussion is presented on managing the data needed for materials selection, including collection, analysis, deployment, and maintenance issues

A novel HLA-B18 restricted CD8+ T cell epitope is efficiently cross-presented by dendritic cells from soluble tumor antigen

NY-ESO-1 has been a major target of many immunotherapy trials because it is expressed by various cancers and is highly immunogenic. In this study, we have identified a novel HLA-B*1801-restricted CD8<sup>+</sup>T cell epitope, NY-ESO-1<sub>88–96</sub> (LEFYLAMPF) and compared its direct- and cross-presentation to that of the reported NY-ESO-1<sub>157–165</sub> epitope restricted to HLA-A*0201. Although both epitopes were readily cross-presented by DCs exposed to various forms of full-length NY-ESO-1 antigen, remarkably NY-ESO-1<sub>88–96</sub> is much more efficiently cross-presented from the soluble form, than NY-ESO-1<sub>157–165</sub>. On the other hand, NY-ESO-1<sub>157–165</sub> is efficiently presented by NY-ESO-1-expressing tumor cells and its presentation was not enhanced by IFN-γ treatment, which induced immunoproteasome as demonstrated by Western blots and functionally a decreased presentation of Melan A<sub>26–35</sub>; whereas NY-ESO-1<sub>88–96</sub> was very inefficiently presented by the same tumor cell lines, except for one that expressed high level of immunoproteasome. It was only presented when the tumor cells were first IFN-γ treated, followed by infection with recombinant vaccinia virus encoding NY-ESO-1, which dramatically increased NY-ESO-1 expression. These data indicate that the presentation of NY-ESO-1<sub>88–96</sub> is immunoproteasome dependent. Furthermore, a survey was conducted on multiple samples collected from HLA-B18+ melanoma patients. Surprisingly, all the detectable responses to NY-ESO-1<sub>88–96</sub> from patients, including those who received NY-ESO-1 ISCOMATRIX™ vaccine were induced spontaneously. Taken together, these results imply that some epitopes can be inefficiently presented by tumor cells although the corresponding CD8<sup>+</sup>T cell responses are efficiently primed in vivo by DCs cross-presenting these epitopes. The potential implications for cancer vaccine strategies are further discussed