Central European Journal of Engineering最新文献

{"title":"Shaping traffic flow with a ratio of time constants","authors":"N. Birlea","doi":"10.2478/s13531-013-0156-z","DOIUrl":"https://doi.org/10.2478/s13531-013-0156-z","url":null,"abstract":"In this paper we present how the main parameters of an optimal velocity model, the velocity adaptation time, τ, and the desired time gap between consecutive vehicles (time headway), T, control the structure of vehicular traffic flow. We show that the ratio between the desired time gap and the velocity adaptation time, T /τ, establishes the pattern formation in congested traffic flow. This ratio controls both the collective behavior and the individual response of vehicles in traffic. We also introduced a response (transfer) function, which shows how perturbation is transmitted between adjacent vehicles and permits the study of collective stability of traffic flow.","PeriodicalId":407983,"journal":{"name":"Central European Journal of Engineering","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123960420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vehicle dynamic analysis using neuronal network algorithms","authors":"Florin Oloeriu, O. Mocian","doi":"10.2478/s13531-013-0153-2","DOIUrl":"https://doi.org/10.2478/s13531-013-0153-2","url":null,"abstract":"Theoretical developments of certain engineering areas, the emergence of new investigation tools, which are better and more precise and their implementation on-board the everyday vehicles, all these represent main influence factors that impact the theoretical and experimental study of vehicle’s dynamic behavior. Once the implementation of these new technologies onto the vehicle’s construction had been achieved, it had led to more and more complex systems. Some of the most important, such as the electronic control of engine, transmission, suspension, steering, braking and traction had a positive impact onto the vehicle’s dynamic behavior. The existence of CPU on-board vehicles allows data acquisition and storage and it leads to a more accurate and better experimental and theoretical study of vehicle dynamics. It uses the information offered directly by the already on-board built-in elements of electronic control systems. The technical literature that studies vehicle dynamics is entirely focused onto parametric analysis. This kind of approach adopts two simplifying assumptions. Functional parameters obey certain distribution laws, which are known in classical statistics theory. The second assumption states that the mathematical models are previously known and have coefficients that are not time-dependent. Both the mentioned assumptions are not confirmed in real situations: the functional parameters do not follow any known statistical repartition laws and the mathematical laws aren’t previously known and contain families of parameters and are mostly time-dependent. The purpose of the paper is to present a more accurate analysis methodology that can be applied when studying vehicle’s dynamic behavior.A method that provides the setting of non-parametrical mathematical models for vehicle’s dynamic behavior is relying on neuronal networks. This method contains coefficients that are time-dependent. Neuronal networks are mostly used in various types’ system controls, thus being a non-linear process identification algorithm. The common use of neuronal networks for non-linear processes is justified by the fact that both have the ability to organize by themselves. That is why the neuronal networks best define intelligent systems, thus the word ‘neuronal’ is sending one’s mind to the biological neuron cell. The paper presents how to better interpret data fed from the on-board computer and a new way of processing that data to better model the real life dynamic behavior of the vehicle.","PeriodicalId":407983,"journal":{"name":"Central European Journal of Engineering","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130873431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental research made during a city cycle on the feasibility of electrically charged SI engines","authors":"L. Kocsis, N. Burnete","doi":"10.2478/s13531-013-0150-5","DOIUrl":"https://doi.org/10.2478/s13531-013-0150-5","url":null,"abstract":"The paper presents experimental research on performance improvements in a city cycle (operating mostly transient) of a compact class vehicle equipped with a turbocharged SI engine which had attached an electric charger, to improve engine response at low operational speeds. During tests, functional parameters, energy consumption of the electric charger and vehicle performances were measured while driving in two operating conditions: with active and inactive electric charger. The tests were carried out on a well-defined path, in the same driving style, by the same driver.","PeriodicalId":407983,"journal":{"name":"Central European Journal of Engineering","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129158702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The influence of triggers geometry upon the stiffness of cylindrical thin walled tubes","authors":"A. Soica, G. Radu","doi":"10.2478/s13531-013-0125-6","DOIUrl":"https://doi.org/10.2478/s13531-013-0125-6","url":null,"abstract":"Today’s automobile manufacturers are increasingly using lightweight materials to reduce weight; these include plastics, composites, aluminium, magnesium alloys, and also new types of high strength steels. Many of these materials have limited strength or ductility, therefore in many cases the rupture being serious consequences during crashes, underscore Picketta et al. in their studies.Automotive structures must deform plastically in a short period of time, a few milliseconds, to absorb the crash energy in a controllable manner. It must be light and enable economically mass-production [1].FE models rapidly gained acceptance among engineers. Many other factors facilitated the development of vehicle models by shell finite elements since most of the geometry of the structural surfaces was already on computer graphic files.Kee Poong Kim and Hoon Huh emphasize that the crashworthiness of each vehicle part needs to be evaluated at the initial stage of design for good performance of an assembled vehicle. As the dynamic behaviour of structural members is different from the static one, the crashworthiness of the vehicle structures has to be assessed by impact analysis.The paper analyzes the influence of trigger geometry upon the compression of thin-walled cylindrical tubes. Simulations performed on a simple model showed the dependence between triggers area and deformation times as well as the maximum deformations obtained for various speeds at which the simulations ware carried out. Likewise, the geometry of trigger leads to different results.","PeriodicalId":407983,"journal":{"name":"Central European Journal of Engineering","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127724312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reliable analysis for time-fractional nonlinear differential difference equations","authors":"M. Singh, R. N. Prajapati","doi":"10.2478/s13531-013-0129-2","DOIUrl":"https://doi.org/10.2478/s13531-013-0129-2","url":null,"abstract":"In this study, we used HPM to determine the approximate analytical solution of nonlinear differential difference equations of fractional time derivative. By using initial conditions, the explicit solutions of the coupled nonlinear differential difference equations have been derived which demonstrate the effectiveness, potentiality and validity of the method in reality. The present method is very effective and powerful to determine the solution of system of non-linear DDE. The numerical calculations are carried out when the initial condition in the form of hyperbolic functions and the results are shown through the graphs.","PeriodicalId":407983,"journal":{"name":"Central European Journal of Engineering","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122984698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vacuum-sintered body of a novel apatite for artificial bone","authors":"K. Tamura, Tatsushi Fujita, Yuriko Morisaki","doi":"10.2478/s13531-013-0127-4","DOIUrl":"https://doi.org/10.2478/s13531-013-0127-4","url":null,"abstract":"We produced regenerative artificial bone material and bone parts using vacuum-sintered bodies of a novel apatite called “Titanium medical apatite (TMA®)” for biomedical applications. TMA was formed by chemically connecting a Ti oxide molecule with the reactive [Ca10(PO4)6] group of Hydroxyapatite (HAp). The TMA powders were kneaded with distilled water, and solid cylinders of compacted TMA were made by compression molding at 10 MPa using a stainless-steel vessel. The TMA compacts were dried and then sintered in vacuum (about 10−3 Pa) or in air using a resistance heating furnace in the temperature range 1073–1773 K. TMA compacts were sintered at temperatures greater than 1073 K, thus resulting in recrystallization. The TMA compact bodies sintered in the range 1273-1773 K were converted into mixtures composed of three crystalline materials: α-TCP (tricalcium phosphate), β-TCP, and Perovskite-CaTiO3. The Perovskite crystals were stable and hard. In vacuum-sintering, the Perovskite crystals were transformed into fibers (approximately 1 µm in diameter × 8 µm in length), and the fiber distribution was uniform in various directions. We refer to the TMA vacuum-sintered bodies as a ”reinforced composite material with Perovskite crystal fibers.” However, in atmospheric sintering, the Perovskite crystals were of various sizes and were irregularly distributed as a result of the effect of oxygen. After sintering temperature at 1573 K, the following results were obtained: the obtained TMA vacuum-sintered bodies (1) were white, (2) had a density of approximately 2300 kg/m3 (corresponding to that of a compact bone or a tooth), and had a thermal conductivity of approximately 31.3 W/(m·K) (corresponding to those of metal or ceramic implants). Further, it was possible to cut the TMA bodies into various forms with a cutting machine. An implant made of TMA and inserted into a rabbit jaw bone was covered by new bone tissues after just one month because of the high biocompatibility of the TMA implant. TMA vacuum-sintered bodies are promising biomaterials for use as artificial bone materials to regenerate bone parts and produce bone reinforcement structures that are used for bone junctions in dental and orthopedic surgery.","PeriodicalId":407983,"journal":{"name":"Central European Journal of Engineering","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134188288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temperature modulation of the vibrational responses of a flexible fluid-conveying pipe","authors":"A. Adelaja","doi":"10.2478/s13531-013-0128-3","DOIUrl":"https://doi.org/10.2478/s13531-013-0128-3","url":null,"abstract":"In this study, the nonlinear transverse vibration of a flexible pipe conveying hot, pressurized fluid is investigated. The pipe which is subjected to a pinned-pinned end condition extends as a result of several operating variables such as internal fluid temperature variation, pre-stress and internal pressurization. The equation of motion is solved analytically by hybrid Fourier-Laplace transforms, and the effects of inlet temperature, temperature gradient, and coefficient of area deformation are investigated on the natural frequencies and transverse dynamic response of the pipeline. While the inlet temperature and temperature gradient are found to be inversely proportional to the natural frequencies and amplitude of the dynamic response, increase in the coefficient of area deformation has little effect on the natural frequencies for the particular case considered.","PeriodicalId":407983,"journal":{"name":"Central European Journal of Engineering","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122406817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High temperature air oxidation resistance of TiAlCr-Y coated Ti45Al8Nb between 750 °C – 950 °C","authors":"T. Dudziak, P. Datta, H. Du, I. Ross","doi":"10.2478/s13531-013-0132-7","DOIUrl":"https://doi.org/10.2478/s13531-013-0132-7","url":null,"abstract":"This study is concerned with air oxidation of TiAlCr-Y coated Ti45Al-8Nb (at%) alloy between 750 °C–950 °C for 500 hours. It was shown in these tests that at 750 °C, 850 °C and 950 °C, the oxidation degradation increased with temperature: at 750 °C the oxide scale consisted of TiO2/Al2O3/Cr2O3 phases, whilst at 850 °C the oxide scale consisted of TiO2/Al2O3 phases with a small amount of Cr2O3, and larger number of voids. The material exposed at 950 °C showed a significant formation of TiO2 with a small amount of Al2O3 and high number of voids; the formation of Cr2O3 at 950 °C was inhibited mainly due to the formation of volatile CrO3 or CrO2(OH)2 phase.","PeriodicalId":407983,"journal":{"name":"Central European Journal of Engineering","volume":"131 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133843399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Instability of transonic flow past flattened airfoils","authors":"A. Kuzmin","doi":"10.2478/s13531-013-0124-7","DOIUrl":"https://doi.org/10.2478/s13531-013-0124-7","url":null,"abstract":"Transonic flow past a Whitcomb airfoil and two modifications of it at Reynolds numbers of the order of ten millions is studied. The numerical modeling is based on the system of Reynolds-averaged Navier-Stokes equations. The flow simulations show that variations of the lift coefficient versus the angle of attack become more abrupt with decreasing curvature of the airfoil in the midchord region. This is caused by an instability of closely spaced local supersonic regions on the upper surface of the airfoil.","PeriodicalId":407983,"journal":{"name":"Central European Journal of Engineering","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129887002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The modified Adomian decomposition method and the noise terms phenomenon for solving nonlinear weakly-singular Volterra and Fredholm integral equations","authors":"A. Wazwaz, R. Rach, Jun-Sheng Duan","doi":"10.2478/s13531-013-0123-8","DOIUrl":"https://doi.org/10.2478/s13531-013-0123-8","url":null,"abstract":"In this paper, we use the systematic modified Adomian decomposition method (ADM) and the phenomenon of the self-canceling ”noise” terms for solving nonlinear weakly-singular Volterra, Fredholm, and Volterra-Fredholm integral equations. We show that the proposed approach minimizes the computation, when compared with other conventional schemes. Our results are validated by investigating several examples.","PeriodicalId":407983,"journal":{"name":"Central European Journal of Engineering","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133885879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}