Influence of semi-trailer truck operating conditions on road surface friendliness

In order to analyze the influence of semi-trailer truck operating conditions on road surface, a three-dimensional vehicle-pavement coupled model with 14 degrees of freedom is established for simulation and calculation. The influence of the different vehicle operating conditions on the dynamic tire loads, dynamic load coefficient (DLC) and road-friendliness which include road surfaces, vehicle speeds, vehicle loads are analyzed in this study. The results shown that the influence of the road surface roughness and vehicle loads on the tire dynamic load coefficient as well as road-friendliness is very obvious. Especially, the DLC values of the 3rd axle increase from 23.97 %, and 34.88 % when vehicle moves on three different road conditions with a velocity of 20 m/s and fully loaded. Finally, this study result gives the road-friendly limit of driving speed for 5-axle semi-trailer truck when vehicle operates under the different conditions

Comparing the performance of suspension system of semi-trailer truck with two air suspension systems

In order to compare the performance of heavy truck suspension system, a 3D dynamic model with 14 degrees of freedom is developed with the dynamic models of the traditional and new air suspension systems to compare the performance of the air suspension systems for reducing the negative impacts on the road surface when vehicle moves on the different road conditions. Dynamic modes of two different types of the air suspension systems are respectively established and a dynamic load coefficient (DLC) is chosen as objective function which uses Matlab/Simulink software to simulate and determine the values of objective function. The results shown that the performance of the new air suspension system is better than the tradition air suspension for reducing the negative impact on road surface under the different operating conditions of vehicle. Especially, the DLC values of wheels at 3rd axle of vehicle with the new air suspension system are respectively reduced by 6.7 %, 7.0 %, 7.4 %, 7.7 % and 8.5 % in comparison with the traditional air suspension system when vehicle moves on the different pavement conditions a velocity of 20 m/s and fully loaded. In addition, the study results not only can provide a reference for designers but also traffic management to reduce the negative impact on road surface

Ride comfort performance of heavy truck with three control cases of semi-active isolation systems

In order to evaluate the performance of heavy truck’s semi-active isolation systems, a half-vehicle dynamic model with three control cases including the seat controlled, the cab controlled, and the vehicle controlled is respectively established. Matlab/Simulink software and the fuzzy logic controller (FLC) are applied to simulate and control the semi-active isolation systems of the heavy truck under two types of step and random road surfaces. The weighted root-mean-square acceleration responses and the acceleration responses of the vertical driver’s seat and the cab’s pitch angle are chosen as the objective functions. The research results show that the vehicle’s ride comfort is significantly improved by three control cases. Especially, in two simulation studies, the vertical driver’s seat vibration and the cab shake are greatly decreased by using the cab controlled. Therefore, the cab controlled surpasses the other types of control for improving the driver’s ride comfort and controlling the cab shake

Study on the influence of bus suspension parameters on ride comfort

This study proposes a three-dimensional vibration model of bus with 10 DOF (degree of freedom) based on Dragan Sekulić model to analyze the suspension parameters directly influenced ride comfort. The suspension parameters which include the stiffness and damping parameters are analyzed based on the weighted r.m.s. (root-mean-square) acceleration responses of the space of a driver, passenger in the middle part of the bus and passenger in the rear overhang according to ISO 2631-1:1997. The results show that both stiffness and damping parameters of vehicle suspension have important influences on ride comfort. Especially, the stiffness and damping values of vehicle suspension are within the value ranges (0.5k0 ≤ k ≤ 0.75 k0) and (0.5c0 ≤ c ≤ 0.75c0) to improve the ride comfort of driver and passengers

SOME PROPERTIES OF EF-EXTENDING RINGS

In [16], Thuyet and Wisbauer considered the extending property for the class of (essentially) finitely generated submodules. A module M is called ef-extending if every closed submodule which contains essentially a finitely generated submodule is a direct summand of M. A ring R is called right ef-extending if RR is an ef-extending module. We show that a ring R is right ef-extending and the R-dual of every simple left R-module is simple if and only if R is semiperfect right continuous with Sl = Sl &#8804;e RR. We also prove that a ring R is a QF-ring if and only if R is left Kasch and RR(&#969;) is ef-extending if and only if R is right AGP-injective satisfying DCC on right (or left) annihilators and (R &#8853; R)R is ef-extending.</p

A modified technique for studying the automotive vibrations based on Jourdain’s principle

This study proposes a combined method of the multi-body system theory and the Jourdain’s principle to study the automotive vibration. A 3D dynamic model of the automotive is built based on the multi-body system theory, the vibration equations are described based on two methods including a method of the Jourdain’s principle and the traditional method of the Newton-Euler’s principle. Matlab/Simulink software is used to solve the vibration equations under the excitation of the step road. The results show that the acceleration responses of the vertical, pitch and roll vibrations of the vehicle’s body with the Jourdain’s method are similarly in comparison with the traditional method. Therefore, the Jourdain’s method not only is applied for studying the kinetic and dynamic model of multi-body systems but also can be applied for studying the automotive vibration. Especially, nonlinear properties of objects in the vibration model can be clearly described by the Jourdain’s method via the recursive Jacobian matrices

Métamatériaux opto-électroniques

A next generation of electronic and optoelectronic devices with high performances and low cost is expected to take off with films of colloidal quantum dots (CQDs) thanks to their unique electrical and optical properties. CQDs are semiconducting nanocrystals synthesized in solution that behave as artificial atoms. Substantial progresses in CQD film-based optoelectronics has been made over the past decade, but the performances are still limited and governed by the merit and inherited properties of CQDs. Another type of artificial medium, metamaterials, is generating a considerable interest from the nano-optics community because of its promises for beating the diffraction limit, realizing invisible cloaks, and creating negative refractive of index at optical regime. However, many of the potential applications for optical metamaterials are limited by their losses and the lack of active functionalities driven by electricity.Although films of CQDs and metamaterials are studied independently and associated to two distinct fields, their properties are mainly determined by their inner geometry. In addition, the difficult hurdles from each field can be surmounted by cooperating with the other one. This dissertation establishes the first bridge to connect films of CQDs and metamaterials and is a first attempt at exploiting the synergy of different types of artificial media.Firstly, we study plasmonic nanoantenna arrays capable of enhancing the spontaneous photoluminescence of CQDs and provide new fundamental insight into these interactions. Secondly, we report the fabrication and characterization of the first inorganic top-emission infrared quantum dot light-emitting-diodes (QDLEDs). The diodes are developed to serve as a solid platform for studying the CQDs film/metamaterial hybrids. Finally, we insert the plasmonic nanoantenna arrays studied at the beginning of this thesis in our QDLEDs and demonstrate a novel form of electroluminescence in which light is emitted by discrete nanoscale pixels that than be arranged at will to form complex light emitting metasurfaces. Other advantages associated with our metamaterial QDLEDs will also be presented i.e. greatly enhanced brightness, extremely low turn-on voltage, emissive color tunability, and polarized electroluminescence. A series of controlled experiments to probe the operational mechanisms of metamaterial QDLED will be discussed.This demonstration illustrates the enormous synergy of combining different types of artificial matter and suggests that many other opportunities will arise by taking an unified view of the various artificial media developed in physics, chemistry and engineering.Une nouvelle génération de dispositifs électroniques et optoélectroniques combinant hautes performances et bas coût se profile grâce aux promesses des films à boîtes quantiques colloïdales (BQCs) et de leurs propriétés électriques et optiques uniques. Les BQCs sont des nanocristaux semi-conducteurs synthétisés en solution qui se comportent comme des atomes artificiels. Des progrès considérables ont été réalisés durant la dernière décennie pour développer une optoélectronique à base de films BQCs mais les performances des composants réalisés sont toujours limitées par un certain nombre de propriétés propres à ces milieux telles que leur granularité et la présence de ligands à la surface des nanocristaux. Un deuxième type de matériaux artificiels, les métamatériaux, suscite un intérêt considérable de la part de la communauté de la nano-optique en raison des perspectives qu'ils offrent pour surmonter la limite de diffraction, réaliser des capes d'invisibilités et des indices de réfraction négatif en optique. Cependant, un certain nombre des applications potentielles des métamatériaux optiques se heurtent à leurs pertes élevées et au manque de fonctionnalités actives contrôlées électriquement.Bien que les films BQCs et les métamatériaux soient étudiés de façon indépendante et associés à deux champs de recherche distincts, leurs propriétés ont beaucoup d'éléments en commun puisqu'elles sont dans les deux cas largement dictées par leur géométrie interne. Il paraît donc intéressant d'exploiter ces analogies et de voir si les difficultés rencontrées dans chaque discipline ne peuvent pas être surmontées en combinant les deux approches. Cette thèse se propose de jeter les premiers ponts entre films BQCs et métamatériaux et constitue une première tentative d'établir une synergie entre ces deux types de milieux artificiels.Dans un premier temps, nous étudions des réseaux de nanoantennes plasmoniques capables d'exalter la photoluminescence spontanée de BQCs et apportons de nouveaux éléments de compréhension à ces interactions. Ensuite, nous décrivons la fabrication et la caractérisation de LEDs à BQCs inorganiques et émission par le haut. Ces LEDs sont développées de façon à servir de plateforme pour la dernière partie de ce travail qui consiste à hybrider les films BQCs et les métamatériaux. Dans cette dernière partie, nous insérons les réseaux d'antennes plasmoniques étudiés précédemment dans l'architecture des LEDs et démontrons une nouvelle forme d'électroluminescence artificielle. Celle-ci se traduit par l'émission de lumière par des nanopixels discrets qui peuvent être arrangés de façon arbitrairement complexe afin de générer toute une gamme de fonctionnalités. D'autres avantages seront présentés comme une brillance accrue, une tension de seuil extrêmement basse, des longueurs d'ondes d'émission contrôlées par la géométrie et un contrôle total de la polarisation. Une série d'expériences visant à sonder les mécanismes à l’œuvre dans ce nouveau type de LEDs sera présentée.Ce travail illustre le très grand potentiel qu'il y a à combiner différentes classes de matière artificielle et suggère que bien d'autres opportunités découleront d'une vision unifiée des différents milieux composites développés en physique, chimie et ingénierie

Design and Analysis of Ternary m-sequences with Interleaved Structure by d-Transform

Multilevel sequences find more and more applications in modern modulation schemes [4QPSK, 8QPSK,16QAM..]  for the 3G ,4G system air interface [1,2].Furthermore, in modern cryptography they are also widerly used. It is also interesting to point out that the length L of these sequences are composite numbers( L=NS),that means the sequence can be easily implemented by interleaving S subsequences, each of length S.Therefore, the methods to develop multilevel sequence with interleaved structure draw a lot of attentions [3, 4]. In this contribution, a method for design and analysis of ternary m-sequences with interleaved structure is presented, based on the d-transform, Which turns out to be a very effective and versal tool for this purpose. Simulations have been made to verify the theory. We first introduce d-transform and its properties and then work out the procedure to design an interleaving sequence in d-transform. Keywords: d-transform,q-ary sequences, interleaved sequence

Bank Efficiency and Determinants of Bank Profitability: Recent Evidence from Vietnamese Banking System, 2006-2013

This paper adopts a two-step research design. In the first stage, this study examines the efficiency scores of Vietnamese commercial banks during the period 2006-2013. The paper employs stochastic frontier analysis (SFA) technique with input distance function and one-sided inefficiency u, and suppose that the scale of u depends on some environmental factors z. A “one-step” procedure that specifies the frontier and the way in which z affects u will be estimated by maximum likelihood technique. This procedure is in contrast to a “two-step” model that comprises two separated steps: estimate the stochastic frontier first and then using the regression model to assess the effects of z variables on inefficiency level u. The phase of measuring bank-specific efficiency levels aims to (i) evaluate the economics performance changes of Vietnamese banking system throughout period 2006-2013, and (ii) determine whether there are differences regarding to efficiency levels across different bank categories in terms of size and ownership. It shows that average efficiency score of Vietnamese banking system during 2006-2013 was 64%, and in general, technical efficiency level was on an increasing trend with two peaks at 74% and 86.5% in 2008 and 2011, respectively. No efficiency level difference was found between either bank size groups or bank ownership groups. In the second stage, using panel data estimation with system generalized method of moments (GMM) technique, this paper assesses the impacts of possible bank-specific (including technical efficiency level estimated in the first stage), industry-specific and macroeconomic variables on Vietnamese bank profitability. It is found that the level of capital to assets ratio (EQASS), the liquidity ratio (LODEP), technical efficiency (TE) and GDP Growth (GDPGR) have positive impacts on accounting bank performance (ROA); while concentration ratio (CR4) is negatively related to ROA. Remaining variables, namely impaired loan reserve to gross loan ratio (LORES), market share of individual banks (MS) and unemployment rate (UNEMP) are found to have no effects on bank profitability

Influence of damping coefficient into engine rubber mounting system on vehicle ride comfort

This study presents a method to improve vehicle ride comfort using additional damping coefficient values for an internal combustion engine (ICE) rubber mounting system. To analyze the effect of the adding damping coefficient values into the rubber mounting system on vehicle ride comfort, a full-vehicle vibration model with 10 degrees of freedom is established under the combination of road surface roughness and ICE excitations. The damping coefficient values are added into ICE rubber mounting system which are respectively analyzed and evaluated according to the international standard ISO 2631-1 (1997). The study results do not only evaluate the influence of the adding damping coefficients on vehicle ride comfort but also suggest the optimal design solution for ICE mounting system to improve vehicle ride comfort