Search Results

The aim of this work is to apply an innovative adaptive ℒ1 techniques to control flutter phenomena affecting highly flexible wings and to evaluate the efficiency of this control algorithm and architecture by performing the following tasks: i) adaptation and analysis of an existing simplified nonlinear plunging/pitching 2D aeroelastic model accounting for structural nonlinearities and a quasi-steady aerodynamics capable of describing flutter and post-flutter limit cycle oscillations, ii) implement the ℒ1 adaptive control on the developed aeroelastic system to perform initial control testing and evaluate the sensitivity to system parameters, and iii) perform model validation and calibration by comparing the performance of the proposed control strategy with an adaptive back-stepping algorithm. The effectiveness and robustness of the ℒ1 adaptive control in flutter and post-flutter suppression is demonstrated.

An integrated simulation tool has been developed, which is applicable to a wide range of design issues. A key feature introduced for the first time by this new tool is that it is truly a single code, with identical handling of engine, powertrain, vehicle, hydraulics, electrical, thermal and control elements. Further, it contains multiple levels of engine models, so that the user can select the appropriate level for the time scale of the problem (e.g. real-time operation). One possible example of such a combined simulation is the present study of engine block vibration in the mounts. The simulation involved a fully coupled model of performance, thermodynamics and combustion, with the dynamics of the cranktrain, engine block and the driveline. It demonstrated the effect of combustion irregularity on engine shaking in the mounts.

”U” bolts are fixing elements and they are used to clamp an elastic joint. From the past, they still looking as an old design and unfortunately, suspension engineers are not specialists in fasteners and elastic joints. That is why we will show important assumptions and concepts to design and specifications this clamp element “U” bolt and its influence over leaf-springs. Currently, “U” bolt is used to clamp an elastic or elastic-plastic joint of heavy duty suspension, formed by leaf-spring, axle, spring pad, “U” bolt plate. This kind of suspension is typically used to trucks, buses and trailers. We are wondering, which one important assumption that an engineer must be careful when designs a new suspension changing from old designs to an updated technology. We provide a theoretical analysis and a FEA analysis to compare torque efficacy x leaf-spring reactions and what are effects this relationship can cause in a suspension.

The use of microprocessors for the implementation of control functions in aircraft electric systems has become a reality. This paper presents a brief survey of these systems along with a typical system block diagram. A description of the diagram highlights the advantages of microprocessor systems over existing noncomputerized control schemes. The second half of the paper discusses the adaptability of more advanced microprocessor systems in the next generation of aircraft electric systems. These powerful new computers will allow digital control and protection of single unit and paralleled generating and starting systems, as well as providing even more effective built-in-test.

Collins Aerospace, a subsidiary of United Technologies Corporation (UTC), has laid out its plans for what is calling “The Grid” – an 25,000-square-foot advanced electric power systems laboratory for designing and testing next-generation, more-electric aircraft technologies for commercial, military, and business aviation.

This paper will discuss using Astronics “Smart Panel” illuminated control panels to control an electronic power distribution system. A discussion of wiring simplification, automatic control possibilities and real time load monitoring is presented. The challenges of retrofitting the system into older aircraft will be covered as well. The paper also explains Electronic Circuit Breaker technology, arc fault protection, panel lighting technologies, control bus options, displays, and human input technology (buttons and knobs).

IN this paper the authors present some experimental results obtained by using the analysis outlined by Prof. James J. Guest before the Institution of Automobile Engineers, in 1926. To make the experimental work more understandable, they present the essential points of Professor Guest's analysis. Professor Guest begins his analysis of the movements of a car body with the simplest set of conditions and presents a graphical as well as an algebraic solution. He then includes one additional factor after another in his analysis until the principal factors in car suspension are included. After all factors are considered, the essential structure of the simple analysis is retained. The authors' efforts at the experimental determination of the moment of inertia of passenger cars were started in January, 1932, on Sir Charles Dennistoun Burney's “tear-drop” design with which he visited leading American manufacturers.

This paper presents, chemistry, test data and processing procedures on a non toxic and environmentally friendly chrome-free conversion coating alternative with the same level of adhesion and secondary corrosion resistance as that found in chrome containing conversion coating systems. Test data from military and independent sources will be presented on secondary coating adhesion, electrical conductivity, filiform and neutral salt-spray corrosion resistance as compared to chromate based systems .on magnesium, aluminum and zinc and their respective alloys. The European “RoSH” initiative will not allow for the presence of any hexavalent chromium on imported electrical components as of July first of 2006. Trivalent chromium based systems generate hexavalent chromium due to the oxidation of the trivalent chromium and as such will not be allowed.

In automotive electronics on-board diagnostics does the fault diagnosis and reporting. It provides the level of robustness required for the control electronics against various faults. The amount of diagnostic information available via on board diagnostics are depends on the type of vehicle. Pre-supply fuel pump is the component in the common rail hydraulic system. It pumps the fuel from the fuel tank to the inlet valve of the high pressure fuel pump. Electronic control unit synchronizes its operation with high pressure fuel pump. A dedicated driver module in the ECU controls the operation of pre-supply fuel pump. The driver module consist of an ASIC with internal voltage, current monitoring modules for the fault diagnosis and the pre-drivers to control external HS and LS power stages. The software part of the OBD programmed in the internal memory of the ASIC. The “Rds_on” of the power MOSFETs are used for the fault detection purpose.

The simulation system “Roadrunner” has the ability to compute 3-dimensional vehicle behavior during simulated ABS-stops or Traction Control (TC) operation on a PC based test rig system. This can be done in real-time mode with fast DSP (digital signal processor) boards and an ABS/TC-ECU as a ‘Hardware-in-the-loop’ device (HIL) or off-line (non-real-time), on the PC only. In the off-line-mode, the PC additionally performs the ABS/TC control algorithms. The simulated system includes model equations for chassis and wheel movement, hydraulics and road to tire interactions. A driver model enables the reproduction of standard steering maneuvers.

This paper describes the initial works related to the study of Internal Combustion Engines, as an object of mechanical design, at the Universidad Tecnológica de Pereira. It is reported a concise, complete methodology for simple model of internal combustion engine. The emphasis of the paper is placed on the use of the in-cylinder parameters (pressure and temperature) and inertial loads in the crank-slider mechanism to derive the loads that act on all the components of the crank-slider mechanism as well as the theoretical output torque for a given geometrical structure and inertial properties. These loads can then be used to estimate the preliminary dimensions of engine components in the initial stage of engine development. To obtain the pressure and temperature inside the cylinder, under different operation parameters, such as air fuel ratio and spark angle advance, a Zero dimensional model is applied. The heat transfer from the cylinder and friction are not taken into account.

Vehicle electrification is a rapidly growing and developing technology. As with any new technology there are hurdles that must be overcome as development marches forward. Overcoming these obstacles will require new and innovative solutions. One area of electrification that is quickly developing is the ability to convert voltage from AC to DC and from DC to AC. This is important since the battery pack outputs a DC voltage which must be converted to AC to drive the electric motor. The reverse is true when braking, the AC voltage generated by the electric motor is converted to DC in order to charge the battery. The conversion of voltage back and forth is controlled through the use of an inverter. The inverter uses Insulated-Gate Bipolar Transistors or IGBTs which generate heat while in operation. As the IGBTs heat up their efficiency goes down. In order to maintain a high level of efficiency the circuity can be directly cooled through the use of a heat sink.

Presented in this paper is a brief review of momentum exchange theory for Jet Noise Suppression. “Experimental Results from Scale Model Tests” are included. These data exhibit peak to peak attenuation of 20 db along maximum exhaust noise azimuths at a nozzle pressure ratio of 3.1.

A multi vector design tool to accurately predict instrument panel obscuration was developed to insure that critical legal displays in vehicles are not obscured. The concept provides for a computer generated light source shaped to replicate the human eyes. The light source is then projected onto a 3D math based arrangement and the resultant shadows are visible on the instrument panel surface and its displays. Design studios require criteria for the placement of the instrument cluster gages and displays, various controls, switches, and steering column stalks before an interior theme can be completed. Therefore, instrument panel obscuration and visibility must be determined early in the design process. The obscured areas are a function of the instrument panel surface, steering wheel rim, hub, spokes, and the location of the driver's eyes. This light source method allows engineers and designers the ability to quickly determine obscured areas.

Vehicle dynamics is a discipline of mechanical engineering that benefited of significant improvements thanks to the progress of computational engineering. Vehicle dynamics engineers are using CAE for the development of a vehicle with MBS and FEA. The concurrent use of these two technologies is a standard in the automotive industry. However the current simulation process is not fully efficient because local geometrical and material nonlinearities are not accurately modeled in classical MBS software. This paper introduces a methodology for vehicle dynamics simulation integrating MBS capabilities in one single nonlinear FEA environment enabling an accurate modeling of nonlinearity in vehicles.

Mathematical modeling and control of artificial ecosystems, such as MELISSA, require first the study of physical and biological characteristics in optimal and limiting conditions. Following the previous determination of the stoichiometric equations (Spirulina compartment) and regarding the two phototrophic compartments of MELISSA (Rhodospirillaceae and Spirulina), we have first to focus our control study on the growth kinetics for the light source. In this paper, we recall the theoretical equations of microbial growth kinetics and emphasise the problem of the light transfer in a photobioreactor. We present their adaptations to our pilot plant taking into account technological and biological specifics (lamp spectrum, working illuminated volume, growth rate,…). We then develop the principles and structure of the control system and describe tests of both the hardware and software for several steady state configurations.

This paper describes the application of statistical techniques known as Design of Experiments (D.O.E.) to efficiently use the results of numerical analysis data in order to improve the configuration of automotive systems. The general framework of these techniques is presented in a format aiming at the design engineer as their end user. Besides, a case study is presented with the purpose of illustrating their practical use. The first step of the case study is to build predictive models for the behaviour of the automotive system being developed by means of the Response Surface Method (RSM), using the proper D.O.E. options. Once these predictive models are available, automatic numerical optimization algorithms are used to improve the responses of interest for given operating conditions. Finally, the automotive systems are robust designed taking into account that the operating conditions vary randomly.