Automotive window seal design considering external aerodynamic load and surrogate constraint modeling

Installed between metallic DIW (Door in White) panel and nonmetallic door glass, automotive window seals has great influence on customers’ perception of NVH (Noise-Vibration-Harshness) performance. Recently, aerodynamic effect on ride comfort attracts increasing research interest. The external load causes unsteady pressure on glass, which is finally transferred to window seals and leads to complicated vibration and increases interior noise level. However, non-linearities of hyper-elastic material, rubber-glass contact and large deformation behavior make the construction of window seals constraint model much more difficult, thus impeding further analysis and optimization. A new window seal design method is proposed featuring in considering aerodynamics-induced load and nonlinear constraint. Firstly, by SST ? k ? ε (Shear Stress Transport) turbulence model, external flow field of full-scale automotive is established by solving three-dimensional, steady and uncompressible Navier-Stokes equation. With re-exploited mapping algorithm, the overall aerodynamic pressure is extracted and matched to local window as external loads for seals, thus taking into account high speed fluid-structure interaction. Secondly, based on functional equivalence and mathematical fitting, new surrogate constraint model is presented. The unitedseal CLD (Compression Load Deflection) curve is synthesized after translations and transformations from two semi-seal CLD experimental measurements of inner and outer lips. It is then fit to complex exponential function, making seal constraint equivalent to a surrogate elastic constraint with variable stiffness. Experiment is performed to verify the constraint surrogation effectiveness. Finally, case study of window seal design under high speed is investigated. After seal optimization based on the new method, windows seals’ maximal displacements have decreased. The improved seal-glass fitting status shows better NVH quality of window seal in high-speed condition.     

Modelling and controlling of car-following behavior in real traffic flow using ARMAX identification and Model Predictive Control

Nowadays, car following models, as the most popular microscopic traffic flow modeling, are increasingly being used by transportation experts to evaluate new Intelligent Transportation System (ITS) and Advanced Driver Assistance Systems (ADAS) applications. The control of car following is essential due to its safety and its operational efficiency. For this purpose, this paper builds a model of car following behavior based on ARMAX structure from a real traffic data set and presents a Model Predictive Control (MPC) controller. An important advantage of this type of control is its ability to cope with constraints on controls. Since safety and operational efficiency are constraints for car following, therefore we have recruited this type of controller in this study to deal with these constraints. Based on the relative distance and relative acceleration of each instant, the MPC predicts the future behavior of the leader vehicle (LV) and according to this behavior, the acceleration of the follower vehicle (FV) is controlled. The MPC tries to control this acceleration in a way to keep the relative distance at a safe region. To investigate the performance of the designed controller, the result of the system is compared with the behavior of human drivers with similar initial conditions. Also, some other test performances were accomplished to investigate other features such as robustness and the stability of the designed MPC. The simulation results show that the MPC controller has a behavior much safer than that of real drivers and it can provide a pleasant trip for passengers.     

Topological analysis of powertrains for refuse-collecting vehicles based on real routes–Part II: Hybrid electric powertrain

In this two-part paper, a topological analysis of powertrains for refuse-collecting vehicles (RCVs) based on simulation of different architectures (internal combustion engine, hybrid electric, and hybrid hydraulic) on real routes is proposed. In this second part, three different hybrid electric powertrain architectures are proposed and modeled. These architectures are based on the use of fuel cells, ultracapacitors, and batteries. A calculation engine, which is specifically designed to estimate energy consumption, respecting the original performance as the original internal combustion engine (ICE), is presented and used for simulations and component sizing. Finally, the overall performance of the different architectures (hybrid hydraulic, taken from the first paper part, and hybrid electric, estimated in this second part) and control strategies are summarized in a fuel and energy consumption table. Based on this table, an analysis of the different architecture performance results is carried out. From this analysis, a technological evolution of these vehicles in the medium- and long terms is proposed.     

Hydrology, sediment yield, erosion and sedimentation rates in the estuarine environment of the Ria de Vigo, Galicia, Spain

The aim of this study is to provide a budget study with calculated erosion rates. Three methods have been used to calculate sediment yield and denudation rates in the Ria de Vigo: (1) measurements of sediment loads, (2) measurements of sediment accumulation rates at the coast, (3) theoretical calculations of potential denudation. Sediment loads and water discharge were measured over a period of 14 months from May 1997 to July 1998. Two of the tributaries entering the Ria de Vigo were monitored for 12 more months, from May 2000 to May 2001, to observe changes in discharge and sediment loads. This period corresponded with atypical precipitation, with peak monthly values (600 mm) three times higher than those on record.Water rating curves are typically exponential. Suspended and dissolved loads vary for different rivers, showing values of 1.5 to 130 mg/l during 1997/1998. For 2000/2001, these values are twice as high. Suspended load versus discharge relationships for 1997/1998 were logarithmic, but data from 2000/2001 does not fit the same equation. Dissolved loads are several times higher than suspended loads in almost all cases. Dissolved load concentrations vary more widely with discharge than suspended loads. This is probably due to local pollution and contamination from marine spray in areas closer to the sea.Second, erosion rates and bed load sediment yields were calculated from accumulation rates at the Ramallosa Complex. Well-preserved estuarine and tidal sediments, associated with the Minor River, have accumulated in this area during the Holocene. ¹⁴C ages allow calculation of sedimentation rates (SR) for two intervals. The lower interval extends from 2001 to 484 years BP and yields an SR of 1.12 mm/a. The upper interval extends from 484 years BP to the present and has an SR of 3.3–4.4 mm/a. These differences may be explained by basin dynamics as the beach progressively encloses the area and also by human interference. From sedimentary facies analysis it is concluded that 90% to 95% of the accumulated deposits were transferred to the basin as bed load. Muddy deposits (mostly marshes) are better developed at the upper part of the sediment pile, and inner areas, indicating a progressive shallowing and filling up of the basin. Most of suspended load is exported to the ria, whereas the Ramallosa Complex acts as a sediment sink for bed load derived material.Calculated potential erosion rates using Ahnert's [Am. J. Sci. 268 (1970) 243] equation show lower values than those estimated from river load concentrations. Potential erosion rates for the Minor River are higher than for the Lagares River which contrast with mechanical denudation rate values from river loads during 1997/1998 which are higher for the Lagares River. During 2000/2001 MDR values were higher than those of the potential erosion rates for both rivers, in line with the extremely high precipitation. Higher values in the Lagares could be in part due to human interference.     

Mixed assembly line rebalancing: A binary integer approach applied to real world problems in the automotive industry

Industrial organizations have increasingly sought to optimize the resources needed for the manufacture of its products from the competition, in order to maintain their profit margins. The search for balance of resources and balanced distribution of tasks in various types of industrial environments is called balancing. When adjustments are made and adequacy of an assembly line that is already in operation, this process is called rebalancing. This paper presents a case study involving a problem of rebalancing of automotive assembly line in an environment of arbitrarily mixed models of products, also known as mix. The proposed procedure for solving the rebalancing in the company in question is based on Binary Integer Programming, in particular the branch and bound algorithm. For comparison, we used a heuristic method based on precedence diagrams for solving the rebalancing of lines. To evaluate the results obtained between the two procedures were used performance indicators such as number of workstations created, average load of work and level of unbalance. The proposed algorithm has resulted in significant improvements in the production line capacity.     

A New Technique of High-performance and Fast Tensioning Prestressed Anchorage CableEI北大核心

Research purposes: The large-span transition section tunnel of the Badaling Great Wall station on the Beijing-Zhangjiakou high-speed railway with the maximum excavation width of 32.7 m, and the largest excavation area of 494.4 m 2 , is the world's biggest traffic tunnel in the world with the largest excavation width and excavation area, which has difficult construction and high security risks. The initial support system of tunnel is mainly realized by prestressed bolt, prestressed cable and shotcrete. After test, anchor cable tension using the traditional anchor cable construction technology can't meet the design requirements, at the same time, it takes about 30 days to achieve prestressed tensioning. Therefore, we need to study the high-performance fast tensioning prestressed anchor cable technology, to effectively control surrounding rock deformation, to ensure the safety of construction, improve construction efficiency. Research conclusions:(1) The traditional anchor cable construction technology is adopted. The anchor cable tension value is mainly controlled by the grip force between the anchor rope and grouting body and the cohesive force between grouting body and surrounding rock. (2) The grip force between the anchor rope and the grouting body can be increased by about 2 times by increasing the "barb"; The cohesive force between the grouting body and the surrounding rock can be increased by 1.5 times by 6 ~ 7 MPa high-pressure grouting process. (3) The modified sulphoaluminate cement slurry can reach more than 30 MPa within 1 day of the slurry strength, so as to realize fast anchor cable tension within 1 day after grouting completion. (4)The research results can be used for reference in similar prestressed anchorage cable construction projects. © 2018, Editorial Department of Journal of Railway Engineering Society. All right reserved.     

pH variability and CO2 induced acidification in the North Sea

A coupled carbonate system–marine ecosystem–hydrodynamic model is used to simulate the temporal and spatial variability in pH across the southern North Sea as it relates to the environmental and biological processes affecting CO₂, namely, photosynthesis and respiration, riverine boundary conditions and atmospheric CO₂ concentrations. Annual pH ranges are found to vary from < 0.2 in areas of low biological activity to > 1.0 in areas influenced by riverine signals, consistent with observations and previous studies. It is shown that benthic, as well as pelagic, activity is an important factor in this variability. The acidification of the region due to increased fluxes of atmospheric CO₂ into the marine system is calculated and shown to exceed, on average, 0.1 pH units over the next 50 years and result in a total acidification of 0.5 pH units below pre-industrial levels at atmospheric CO₂ concentrations of 1000 ppm. The potential for measurable changes in biogeochemistry are demonstrated by simulating the observed inhibition of pelagic nitrification with decreasing pH. However, we conclude that there is a lack of knowledge of how acidification might affect the complex interaction of processes that govern marine biogeochemical cycles and a consequent need for further research and observations.     

The UNCTAD and WORKPORT models of port development: evolution or revolution?

Around ten years have elapsed since the UNCTAD model on port development was put forward as an explanation of how ports have adapted to incorporate technological, political and operational changes. The UNCTAD Three Generation Port Model is critically examined in the light of research carried out under the WORKPORT project funded by the European Commission, 1998-1999. Evidence from the WORKPORT study shows that, rather than developing in discrete steps, ports evolve continuously, adapting to new technologies, fresh legislation, revised working practices and other influences on an as-required basis. Further, it is demonstrated that several streams of evolution can be observed simultaneously; the pace of change within each stream can vary substantially. One of the prominent features of ports is that they often have several terminals, some operating along traditional lines while others may be leading edge in terms of technology, working practices or other aspects; all of them may be equally effective. The UNCTAD model, implying ports develop in discrete steps, or generations, is therefore shown to be fundamentally flawed.     

An energy‐mobility beach classification system as a basis for the management of beach resources

Abstract

The successful implementation of structural and nonstructural solution to problems of shoreline erosion is greatly facilitated if the accumulation and analysis of data sets are accomplished within a design framework which has both theoretical validity and practical application. An inventory of beach resources based upon breaking‐wave energy and beach mobility is presented as a basis for a beach classification system. This method should be used with existing inventories compiled by the U.S. Army Corps of Engineers. A simplified means of determining changes in beach position and slope is suggested; this will facilitate gathering data in a daily time series at numerous locations by a minimum number of people. Examples of how the inventories may be conducted and a sample classification system are presented for selected portions of the shoreline of New Jersey.     

Multi-fidelity optimization of a high-speed foil-assisted semi-planing catamaran for low wake

The wakes of high-speed passenger-only ferries that operated through Rich Passage, on the Seattle-Bremerton ferry route, caused beach erosion and damage to habitat. A task was initiated to design a low-wake high-speed vessel using multi-fidelity CFD based design optimization by using low-fidelity potential flow solvers for initial global design optimization and by using URANS solvers for high-fidelity tuning of the optimized design. This simulation based design process involved a close collaboration between ship designers, and hydrodynamics and CFD specialists, whose collective expertise guided the evolution of the design based on both hydrodynamic and structural aspects. The initial hull shape optimization using potential flow code was carried out by blending three different initial concepts provided by the designers. Subsequently, URANS was used to evaluate the potential flow optimized hull and to further optimize the hull configuration parameters, namely, the centre-of-gravity, demihull spacing, foil location, foil angle and slenderness ratio at different displacement conditions. The URANS based configuration optimization also took into account the far field wakes’ energy spectrum with an objective of reducing the energetic, low frequency far field wakes which are associated with beach flattening on the mixed sand and gravel beaches. Calculation of the far field wake using URANS would require an unfeasibly large domain size; therefore, a Havelock code with a source distribution matching the URANS calculated near field wave elevation was used to propagate the wakes into the far field. The end result of the optimization was a design with significantly reduced far field wake, which is currently being built for experimental testing.