bluuebunny/crossref_metadata_2025 huggingface dataset:
Catching Continuum Between Preshape and Grasping Based on Fluidics
Authors: Ozyer Baris , Erkmen Ismet , Erkmen Aydan M.
Published: January 2011

We propose a new fluidics based methodology to determine a continuum between preshaping and grasping so as to appropriately preshape a multifingered robot hand for creating an optimal initialization of grasp, with minimum energy loss towards task execution, upon landing on an object. In this paper, we investigate the effects of impact forces and momentum transfer between different hand preshapes landing on an object. Momentum transfer parameters lead to modification of object orientation and position at the very initial stage of task after that preshaped fingers land on the object. We model fingers as particles in a solidified environment while the medium squeezed by hand preshape that is closing upon an object, is modeled as a compressible fluid where momentum is propagated until hitting the surface of the solidified particle medium of the object. Smoothed particle hydrodynamics model (SPH) is used to simulate the general dynamic of fluid flows and momentum transfer between particles of different media. The fingers of the robotic hand are modeled by solidified fluid particles interacting with compressible surrounding fluids in which objects are defined as rigid-body solidified fluid particles. The developed model has been applied, in this paper, to the simulation of various simple robot hand preshaping and the generated momentum transfer profiles an object surface have been analyzed.
Conception and Evaluation of Sustainable Cross-Company Logistics Models
Authors: Sihn Wilfried , Hillbrand Christian , Prochazka Margarethe , Meizer Felix , Leitner Rene´
Published: January 2011

Business networking strategies and especially co-operation in logistics is gaining momentum for individual companies in order to survive in competitive markets. As cross-company transport bundling is a powerful approach to optimize cost structures, this publication deals with the conceptual design and evaluation of cross-company logistics models. For this purpose, a simulation and evaluation model is presented that supports the development of new logistics concepts. Therefore models for the calculation of emissions, costs and logistics competitiveness, have to be created and combined to holistically validate and evaluate the new approach. This combination between the three different target values distinguishes the developed model from already published methods. Based on the sustainable, company-wide approach, potentials for optimization in the areas emissions, costs, and logistic competitiveness can be detected and by means of these analysis results, new sustainable and energy efficient logistics models can be designed.
Powertrain Control of Parallel Hybrid Electric Vehicles via Extremum Seeking Algorithm
Authors: Dinc¸men Erkin , Uygan I˙smail M. C. , Gu¨venc¸ Bilin Aksun , Acarman Tankut
Published: January 2011

A control algorithm for a parallel hybrid electric vehicle is proposed in this paper. An upper level controller chooses vehicle operation mode such as regenerative braking, electric motor only, combustion engine only, engine+motor in battery discharge or engine+motor in battery charge modes. In engine+motor mode, optimum torque distribution between the engine and the motor is determined via extremum seeking algorithm that searches maximum drivetrain efficiency. Simulations are given to illustrate the effectiveness of the proposed control algorithm.
Experimental and Numerical Investigation of a Centrifugal Compressor
Authors: Karrabi Hadi , Hajilouy-Benisi Ali , Nili-Ahmadabadi Mahdi
Published: January 2011

In this research, centrifugal compressor of a gas turbine is investigated experimentally and numerically. Operation line of the compressor as a component of the gas turbine is obtained experimentally by measurements of impeller rotational speed, and flow parameters at the compressor inlet and outlet during the gas turbine operation. The flow field inside the impeller and diffusers are analyzed numerically using a full 3D Navier-Stokes program with SST turbulence model. Boundary conditions for the numerical simulation are specified from the experimental measurements. The operation line of the compressor is obtained numerically, which is compared with that of the experimental results, and shows good agreement. Having validated the numerical results, the performance characteristic curves of the compressor are obtained numerically in a wide range.
Buckling Delamination of the Rectangular Orthotropic Thick Plate With an Edge Rectangular Crack
Authors: Akbarov Surkay , Yahnioglu Nazmiye , Karatas Esra Eylem
Published: January 2011

The buckling delamination problem for the rectangular plate made from composite (orthotropic) material is studied. It is supposed that the plate has a rectangular edge-crack and edge-surfaces of that have an initial infinitesimal imperfection. The development of this initial imperfection with an external compressive loading acting along the crack is studied in the framework of the three-dimensional geometrically nonlinear field equations of the elasticity theory of anisotropic bodies. For the determination of the values of the critical force the initial imperfection criterion is used. The corresponding boundary-value problems are solved by employing the boundary form perturbation techniques and the FEM. The influence of the material or geometrical parameters of the plate on the values of critical force is discussed.
Static Analysis of a Functionally Graded Piezoelectric Beam Using Finite Element Method
Authors: Eshraghi Iman , Yousefi-Koma Aghil
Published: January 2011

In this study static analysis of functionally graded piezoelectric material (FGPM) beams is performed using finite element modeling. First order shear deformation beam theory (Timoshenko beam theory) with the assumption of linear strain-displacement relations is used for modeling of displacement and strain fields in the beam. Theoretical formulations are derived employing Hamilton’s principle using linear constitutive relations of piezoelectric materials and including the effect of transverse shear deformation. Finite element method with one dimensional linear continuum isoparametric element, three displacement mechanical degrees of freedom, and one electric potential degree of freedom assigned to each node is then used to investigate the bending behavior of FGPM beam actuator under thermo-electro-mechanical loads. Consequently, a parametric study of the bending behavior of an FGPM beam is performed. The effects of slenderness ratio and fraction of volume of constituent materials, on the thermo-electro-mechanical characteristics are studied. It is shown that under electrical loading the beam represents the so-called non-intermediate behavior.
Mechanical Design and Analysis of an Intelligent Oil Well Sensory System
Authors: Salmasi Atefeh , Yousefi-Koma Aghil , Soorgee Mohammad Hossein
Published: January 2011

Optimal revenue of oil and gas fields is of interest due to high price and limited amount of these sources of energy. In this way, smart well technology provides a numerous range of benefits and for these great advantageous is widely used in oil/gas industry. This technology involves down-hole measurement and control of well bore and reservoir flow. One of the most important down-hole control subsystems in a smart well is pressure and temperature sensing system which can help the reservoir being modeled accurately. The purpose of this paper is to design and analysis a new sensory package for a desired oil well. A brief review of the advantages of fiber optic sensing technology in smart well control system is performed. Having studied several possibilities of installation systems for sensors, a new arrangement and casing for temperature/pressure sensor is developed here. Effect of pressure and temperature on stress distribution in the casing has been investigated and a suitable casing is obtained.
The Performance of Bolted Slant Endplate Connections Subjected to Temperature Increase
Authors: Zahmatkesh F. , Talebi E.
Published: January 2011

In this paper the main goal is to evaluate the vertical and slant bolted endplate connections performance in steel moment frame structures under thermal effect in elastic field, and by a finite element software. the connections are simulated to complete and verify simple modeling of analytical and numerical analysis of the behavior of vertical and slant bolted endplate connections due to increase in temperature. The results that are obtained from performance of a vertical bolted endplate connection and a slant bolted endplate connection due to increase in temperature will be compared.
Neural Network Weight Optimisation Using the Bees Algorithm
Authors: Ghanbarzadeh Afshin
Published: January 2011

This paper presents an application of the Bees Algorithm (BA) to the optimisation of weights within neural networks for wood defect detection. This novel population-based search algorithm mimics the natural foraging behaviour of swarms of bees. In its basic version, the algorithm performs a kind of neighbourhood search combined with random search. Following a brief description of the algorithm, the paper gives the results obtained for the wood defect identification problem demonstrating the efficiency and robustness of the new algorithm.
Theoretical and Experimental Crushing Analysis of Metal Square Honeycombs Under Quasi-Static Loading
Authors: Zarei Mahmoudabadi M. , Sadighi M. , Eyvazian A.
Published: January 2011

Honeycomb cellular structures, due to their light weight and high energy absorbing, have been used extensively as energy absorbers or cushions to resist external loads. In this paper, the mean crushing stress and the wavelength of the folding mode, as two important parameters in the study of metal square honeycomb crushing under quasi-static loading have been investigated theoretically and experimentally. Firstly, by considering the true cylindrical curvature effects and the flow stress in the folding mode of the honeycomb material, the Wierzbicki’s model in the study of metal hexagonal honeycomb crushing under quasi-static loading is modified. This modification is performed by rewriting the internal energy terms and the external work in the energy method through the basic element folding by considering the true cylindrical curvature effects and the flow stress of the honeycomb material. Comparison of the results obtained by this modified model and Wierzbicki’s model with the experimental data shows better prediction by the model presented in this paper. Subsequently, this modified model has been extended to the study of metal square honeycombs crushing under quasi-static loading and the mean crushing stress and the wavelength of the folding mode of these structures have been predicted. This analytical model predicts the mean crushing stress of the metal square honeycomb as a function of both the geometrical parameters and its material, while the predicted wavelength of the folding mode is just a function of the geometrical parameters. Finally, the experimental tests have been performed to verify the preciseness of this theoretical model.
Design of a Francis Turbine for a Small Hydro Power Project in Turkey
Authors: Celebioglu Kutay , Okyay Gizem , Yildiz Mehmet
Published: January 2011

Many hydro power plants, both in small and large scales, are being constructed in Turkey. The total potential of these projects reach to 216 billion kWh of feasible energy. However a method was not yet developed for the design of hydraulic machinery equipment in Turkey. In order to accomplish the hydraulic turbine design without any prior information than the design parameters of the hydraulic project, a methodology is developed. This methodology involves the use of computational tools and it is applied for small hydro projects. This methodology is a parametric design-optimization procedure which consists of parametric geometry modeling, computational fluid dynamics analysis and structural verification.
Design and Modeling of a Novel In-Pipe Microrobot Using IPMC Actuators
Authors: Vahabi Meisam , Mehdizadeh Emad , Kabganian Mansour , Barazandeh Farshad
Published: January 2011

Majority of researchers’ activities in microrobotics and MEMS fields has been devoted to fabrication processes and design. Lack of work on modeling, simulation and control is considerable. From the viewpoint of motion type, the most significant microrobots are the in-pipe ones. Some of the applications for the in-pipe microrobots are nozzle inspection, endoscopy, colonoscopy etc. IPMC is a new actuator in the class of EAPs. Large bending deflection, mechanical flexibility, low excitation voltage and low density make IPMC a very momentous actuator. This paper presents a new in-pipe microrobot that makes use of IPMC actuators to move the microrobot. Mathematical model of the microrobot is obtained using the extended Hamilton principle. This microrobot motion has four steps in every single movement cycle for which only two feet take part in each step. Thus the modeling process has to be done for the different steps apart. This problem considerably increases the complexity of the model. Another source that complexes the modeling process is due to the nonlinear model of IPMC actuator. Also the influence of IPMC actuators at each other has been examined.
Evaluation of Random Stack Materials for Use in Thermoacoustic Refrigerators
Authors: Mao Xiaoan , Saechan Patcharin , Jaworski Artur J.
Published: January 2011

In a thermoacoustic refrigerator, energy conversion between thermal and acoustic power is achieved by means of an oscillatory motion of a compressible fluid along a solid body referred to as “stack”. Traditionally, stacks have been most often made by arranging large number of thin plates at equal spacing to fill out the cross section of a thermoacoustic resonator. Other geometries such as circular pores, square or hexagonal pores (honeycombs) or pin-arrays can also be considered. Most common irregular geometry includes layers of woven wire mesh stacked along the resonator length. The advantages of thermoacoustic engines over other conventional energy conversion devices lie in their relatively simple hardware assembly, without the need for any dynamic sealing and lubrication. However, the fabrication of stacks, for example made out of very thin parallel plates, is usually costly and impractical, while using pre-fabricated stacks (e.g. ceramic catalytic converter substrates or honeycomb used in aerospace industry) has high materials costs, which limits the cost advantages of thermoacoustic engines. However, many of these problems could be avoided if irregular stack geometries made out of random (very often waste) materials could be used. There is a wide range of such candidate materials, including glass or steel wool, ceramic chippings, waste material from metal machining (swarf, Scourers), beds of glass or metal balls etc. However the main difficulty is the lack of experimental data characterising the performance of such stacks at the design stage. In this paper, the performance of a standing wave thermoacoustic refrigerator with a stack made of a few chosen random materials, is measured and compared to the one with a parallel plate stack. It is hoped that this work will be beneficial for developing low-cost thermoacoustic prime movers and heat pumps.
Passive Feedback Unit for Steer by Wire Systems
Authors: Quaglia Giuseppe , Scopesi Marco , Pepe Fortunato , Rossi Mario
Published: January 2011

Steer by Wire systems remove the need of a mechanical connection between the governing unit (steering wheel) and the actuated element (steered wheel). With respect to traditional steering systems, SbW systems replace complex mechanical and/or hydraulic components with simple mechatronic components that enable programmable steering features, enhancements in cab design, ergonomics and safety, plus advantages in simplified assembly, all at a cost comparable to traditional systems. The objective of this article is to show how the idea of passive SBW system can be translated into an actual device ready for vehicle applications. To fulfill this aim, functional schemes, mechanical and mechatronic structure and some data about obtainable performance are presented.
New Stirling Motor Design With Efficiency by Using Ceramic Components
Authors: Usbeck Anna Kerstin , Schmidt Jens , Krause Dieter
Published: January 2011

The Institute for Product Development and Mechanical Engineering Design (PKT) at the Hamburg University of Technology (TUHH) is developing a new generation of Stirling motors for small combined heat and power plants up to a range capacity of 5 kW mechanical power output. Main objective of the project is to increase the efficiency of the Stirling motor. Reducing friction, wear and heat conductivity are the key benefits for the application of ceramic components in high loaded tribological contacts; furthermore the principle of the Stirling motor requires a lubricant free gas circuit. The applied systematically design process, based on product functions and active principles allows a target-oriented development of concepts for all components and assemblies of the Stirling motor. No simple substitution of metallic into ceramic components has been taken place, but rather a “design for ceramic” has been applied to use advanced ceramic materials in an optimal manner. Before manufacturing a prototype of the Stirling motor, mechanical tests of the main tribological contacts are intended. For these tests the authors’ institute will use two existing test rigs, the NPT (non-proportional tension-torsion test) and the MPH (Mechanische Pru¨fung von Hydraulikflu¨ssigkeiten–Mechanical Testing of Hydraulic Fluids) to investigate strength, friction and wear of the ceramic components. Within this paper at first a brief overview of the Stirling motor principle and the functions of the key components will be given. Based on this and from the tribological point of view the main requirements of the motor parts will be derived. The description of the developed motor concept with ceramic as a high temperature material will be the main part of the paper, followed by the description of the intended rig tests to analyse strength, friction and wear behaviour of the chosen ceramic materials.
Data Fusion of Non Destructive Testing for Detection of Defects in Welding
Authors: Farzaneh R. , Safizadeh M. S. , Goodarzi M. , Seyrafi M.
Published: January 2011

In this paper the specimens of Aluminum 2024 with 5 millimeter in thickness are joined together by friction stir welding with travel speed of 100 mm/min and tool rotational speeds of 450, 900 and 1800 rpm and a tool were made of hot working steel, H13, firstly. Thus three kinds of welds are produced. Radiography and ultrasonic (UT) non-destructive testing (NDT) procedure were applied to characterize the presence and geometry of possible weld defects prior to mechanical destructive testing. A Echograph Model 1090 digital UT instrumentation and a 4 MHz angle beam probe (refraction angle α = 70°) was used for C-scan of UT contact testing of welded samples (transverse UT velocity 2850 m/s and signal amplification 40 dB). The detection accuracy of defects can be improved by image fusion of ultrasonic and radiography data. For this reason, the data of the two sensors are transformed into a same scale images (length, width and also depth). Pixel by pixel image fusion is used for fusion and analysis. Comparing these results with the destructed part shows that the fusion of two tests improves the results.
Numerical Simulation of the Hemodynamics in 6 mm and 6–8 mm Hemodialysis Grafts and Investigation of Biomechanical Consequences
Authors: Sarmast Mohammad , Niroomand Oscuii Hanieh , Ghalichi Farzan , Samiei Ehsan
Published: January 2011

Hemodialysis vascular access dysfunction is still considered as a major cause of morbidity and mortality in hemodialysis patients. The most common cause of this vascular access dysfunction is venous stenosis secondary to the progression of venous intimal hyperplasia at the graft-vein junction or in the draining vein. The geometry of the vessels and the local hemodynamics are believed to be contributory factors in the development of intimal hyperplasia. In the present study, the hemodynamic parameters in two types of vascular access grafts of different diameters: 6 mm and 8 mm tapered to 6 mm at the arterial site were compared. A three-dimensional CFD model was developed to simulate blood flow in the two graft types. The boundary conditions applied were a pulsatile velocity waveform at the arterial inlet and a pulsatile pressure waveform at the venous outlet. Computational fluid dynamics software was used to solve the time dependent Navier-Stokes equations under physiological conditions in both graft types. Since the cross section area and the diameter of the venous side of the tapered graft are larger than those of the straight one, the flow aligns well with the vein downstream of the graft and hence the smaller vortices are generated. Comparing the parameters at the two venous anastomosis regions also indicates that in spite of the higher flow rate in 6–8 mm tapered graft, the velocity and the wall shear stress values are lower than the values of the 6 mm straight graft.
Vehicle Yaw Motion Control Using Takagi-Sugeno Modeling and Quadratic Boundedness via Dynamic Output Feedback
Authors: Mammar Sai¨d , Nouvelie`re Lydie , Minoiu-Enache Nicoleta , Glaser Se´bastien , Lusetti Benoit , Gruyer Dominique
Published: January 2011

This paper presents the design and the simulation test of a Takagi-Sugeno (TS) fuzzy output feedback for yaw motion control. An integrated steering and differential braking controller based on invariant sets, quadratic boundedness theory and a common Lyapunov function has been developed. The TS fuzzy model is able to handle elegantly the nonlinear behavior the vehicle lateral dynamics. The computation of the control law has been achieved using Linear and Bilinear Matrix Inequalities (LMI-BMI) methods. Simulation test shows the controlled car is able to achieve the ISO3888-2 transient maneuver. Some design parameters can be adjusted to handle the tradeoff between safety constraints and comfort specifications.
Assembly Concepts for Aircraft Cabin Installation
Authors: Halfmann Niklas , Krause Dieter , Umlauft Sebastian
Published: January 2011

The development of visionary integration concepts for the aircraft cabin is essential for the reduction of assembly times. In this paper the results of multiple joint research projects between the Hamburg University of Technology and Airbus Operations GmbH are presented. Based on an extensive as-is analysis, first concepts were set up applying prevalent design for assembly guidelines and resulting in the definition of top-level-requirements for the design and installation processes of aircraft cabins. Further research contained an analysis of the assembly processes of the cabin components in relation to their product structures. Concepts were generated using the PKT own developed modularization method. The method considers all relevant strategic perspectives of a company, one of which is the assembly. At the end a final assembly line optimized concept was defined. The concept mainly concentrates on the over-head storage bins, the so called Hatracks, the passenger service units (PSUs) and the lining panels. Since in the common way, all components are separately handled and mounted, their installation turned out to be the bottle neck of the assembly process. According to the developed measures, the degree of pre-assembly is raised. Thereby time intensive assembly tasks are parallelized and performed independently outside of the aircraft in earlier production phases. Due to the geometric dimensions and weight of the resulting cabin modules in this context, the utilization of a handling device becomes obligatory. The positive effects on the overall lead time reduction are evaluated. For all developed concept aspects technology demonstrators were constructed representing the overall installation process. Tests were performed in order to validate the estimated benefits.
Economic Feasibility Study of a Small Scale Organic Rankine Cycle System in Waste Heat Recovery Application
Authors: Tchanche Bertrand F. , Quoilin Sylvain , Declaye Sebastien , Papadakis Georges , Lemort Vincent
Published: January 2011

The Organic Rankine Cycle (ORC) appears progressively as a promising solution to recover waste heat energy from thermal processes for electricity generation. A prototype of small-scale ORC has been built and successfully tested at the University of Lie`ge. It uses R-245fa and R-123 as working fluid, and an oil-free scroll compressor adapted to run in expander mode. Thermodynamic model of the system was derived and validated for performance prediction. The validated thermodynamic model is used to optimize the operation of the small ORC in waste heat recovery application (ORC-WHR). For exhaust gases at 180 °C and a mass flow rate of 0.21 kg/s, a maximum net power output of 2 kWe is obtained for an evaporator pressure of 11.84 bar. The cycle thermal efficiency is 8.23 and the recuperation efficiency, 66.32%. Based on the aforementioned conditions, the economic assessment of small scale ORC-WHR was carried out using economic criteria such as levelized electricity cost (LEC), Net present value (NPV) and depreciated payback period (DPP). For a 2kWe ORC-WHR, the specific installed cost is 5775 €/kW with a LEC of 13.27 c€/kWh while for a 50 kWe, the specific installed cost is about 3034 €/kW and the LEC, 7c€/kWh. For an electricity unit price of 20 c€/kWh, the payback period of a 2 kWe system is 6 years while it is 2.5 years for a 50 kWe system. It is concluded from the study that recovering the waste heat by way of ORCs is technically and economically feasible. As recycled energy, waste heat has the same advantages as renewable energy and should benefit from the same legislative conditions (Feed-in-Laws).
Optimal Coupled Spacecraft Rendezvous and Docking Using Multi-Objective Optimization
Authors: Moradi Rouzbeh , Pourtakdoust Seid H. , Kamyar Reza
Published: January 2011

Spacecraft rendezvous and docking are two processes in which a chaser pursues and meets a leader spacecraft in order to perform several mission based tasks. Although in some preliminary design analysis, these two operations may be pursued independently there could be circumstances in which the spacecraft trajectory and attitudes are coupled and interdependent. The present study is based on the presumption that the often independent translational and rotational motions of the spacecraft are coupled as a result of thrust misalignment. So the thrusters not only contribute to the rendezvous translational motion, but also affect the docking reorientation maneuver through their disturbing effects. In this regard, the coupled spacecraft rendezvous and docking (RvD) maneuver is treated as a multi-objective optimization problem. Multi-objective ant colony optimization (ACOR) and Genetic algorithm (GA) as new variants of multi objective metaheuristics that have proven to be successful in handling non convex and multi minima problems are utilized to determine the required pareto front. Three design points are selected such that a wide range of mission based operations are covered and the results are compared. It is shown that, despite the presence of the disturbing effects due to the thruster misalignment, the required control commands are reasonable. For a comparative analysis, two different schemes are also utilized to obtain the closed loop control form for the RvD problem under study and their results are compared.
Performance Analysis and Optimization of High Capacity Pulse Tube Refrigerator
Authors: Ghahremani Amir R. , Roshanghalb F. , Jahanbakhshi R. , Saidi M. H. , Hannani S. Kazemzadeh
Published: January 2011

High capacity pulse tube refrigerator (HCPTR) is a new generation of cryocoolers tailored to provide more than 250 W of cooling power at cryogenic temperatures. The most important characteristics of HCPTR when compared with other types of pulse tube refrigerators are a powerful pressure wave generator, and an accurate design. In this paper the influence of geometrical and operating parameters on the performance of a double inlet pulse tube refrigerator (DIPTR) is studied. The DIPTR is modeled applying the nodal analysis technique, using mass, momentum and energy conservation equations. The model is able to compute instantaneous flow field throughout the system and calculate cooling capacity and COP. The model is validated with the existing experimental data. To perform the optimized mode of operation, the influence of both geometrical and operating parameters on cooling capacity and COP is investigated. The key geometrical parameters considered in this paper are aspect ratios of regenerator and tube section, length ratio of regenerator and tube, and type of screen mesh. The main operating parameters considered are average charge pressure, and position of opening of orifice and bypass. As a result of this optimization a new configuration of HCPTR is proposed. This configuration provides 300 W at 80 K cold end temperature with a frequency of 50 Hz and COP of 0.054.
Structural Analysis of Riveted Structures Using a New FE Modelling Technique
Authors: Ferracci Michele , Vivio Francesco , Vullo Vincenzo
Published: January 2011

A theoretical approach, in order to define the structural behaviour of riveted joints, is presented. The closed form solutions lead to the definition of a Rivet Element useful to FE models of multi-riveted structures. The objective is an accurate evaluation of the local stiffness of riveted joints in FE analysis, which is fundamental to perform a reliable simulation of multi-joint structures and, consequently, a good estimate of loads acting on connections; this makes it possible to introduce new general criteria allowing, for example, to predict fatigue behaviour. On the other hand, a low number of degrees of freedom is needed when several connections are present in a complex structure. The goal is to reach a reliable model of the rivet region which can be used as the basis to develop a Rivet Element in FE analysis. The proposed Rivet Element combines the precision in the simulation with a very limited number degrees of freedom in the finite element model of a complex structure having several rivets. In the present paper the structural behavior of two simple riveted specimens is investigated experimentally and numerically using a new Rivet Element. A comparison with a joint model performed with very refined non-linear 3D models of rivet and with experimental data is performed and a good agreement is shown.
Thermodynamic Analysis of a Combined Power and Water Production System
Authors: Shakib S. Ehsan , Amidpour Majid , Aghanajafi Cyrus
Published: January 2011

Most of the potable water and electricity are produced by dual purpose plants. Dual-purpose plants are the one that supplies heat for a thermal desalination unit and produces electricity for distribution to the electrical grid. In this paper a power plant is combined with a multi-effect evaporation thermal vapor compression (METVC) system. Compared with the most widely used (Multi Stage Flash) MSF desalination, METVC has more advantages. Then, energy and exergy analysis equations for desalination plant, power generation cycle, heat recovery steam generator and combined power and water cycle are developed and the results are presented. Results show by rising number of effect from 2 to 14, performance ratio, exergy efficiency and specific heat transfer area rise steadily. For combined system, the maximum and minimum values of exergy destruction rate are related to combustion chamber and desalination effects, respectively. Also, with increasing TIT, exergy destruction rate of power generation cycle decreases while the exergy destruction rate of METVC, especially thermo compressor, goes up and fresh water production reduces dramatically.
Representation of the Operational Behaviour of an Educational Robot at Conceptual Design Using Petri Nets
Authors: Erden Zu¨hal
Published: January 2011

Increasing demand for computational support at conceptual design makes behavioural modeling a challenging area for design research. This is mainly because a behavioural model of a nonexistent design artifact at conceptual level is the basis for behavioural simulation and resulting computational design support. Behavioural models are particularly important for top-down design of multidisciplinary products such as mechatronic systems. During the conceptual design of such systems, intended “operational behavior” of the artifact is described without any physical realization. As design stages become more concrete, operational behaviour can be refined so as to represent well defined mathematical descriptions of corresponding physical behaviors. In this study, a model for representing the intended operational behaviour of a nonexistent educational robot, namely a rabbit robot, is presented for conceptual design. The operational behaviour of the robot is defined as composed of states and state transitions independent of any physical embodiment. Discrete Event System Specification (DEVS) and Petri Net formalism are used for the model. This representational model is the first step towards the development of a virtual prototype for the operational behaviour of an educational robot.
A Successful Model of Cooperation Between a Public University and Industrial Companies Through a Hybrid Public/Private R&D Institute
Authors: Lino F. Jorge , da Rocha A. Barata
Published: January 2011

The pattern of Portuguese Industry is typically composed by small and medium sized enterprises. In many cases, the dimension of these companies unable a general innovation culture for their products, with their own human resources. In these cases, innovation can successfully be achieved through suitable cooperation models and technological transfer between Universities and/or its Research and Development (R&D) Interface Organizations. This paper describes a successful model of cooperation between a hybrid private/public Institute, INEGI, with more than 60 Industrial Associates and National and International Industrial Companies. It is also shown the advantage of having industrial R&D Projects running inside the Faculty and the benefits obtained with the involvement of students in these projects. Examples are presented with paradigmatic projects, with high industrial impact, leading to effective competitive growth, both on Portuguese and International companies. The intervention areas of these projects cover a large variety of multidisciplinary topics, from renewable energies, processes and mechanical systems development, composite structures, rapid prototyping and advanced technologies, industrial management, to the creation of technological spin-offs.
A Simulation Based Framework for Discovering Planning Logic for Autonomous Unmanned Surface Vehicles
Authors: Svec Petr , Schwartz Max , Thakur Atul , Anand Davinder K. , Gupta Satyandra K.
Published: January 2011

This paper describes a computational framework for automatically synthesizing planning logic for unmanned surface vehicles (USVs). The basic idea behind our approach is as follows. The USV explores the virtual environment by randomly trying different moves. USV moves are simulated in the virtual environment and evaluated based on their ability to make progress towards the mission goal. If a successful action is identified as a part of the random exploration, then this action is integrated into the logic driving the USV. This approach has been utilized for automatically generating planning logic for USVs. The planning logic is represented as a decision tree which consists of high-level controllers as building blocks, conditionals and other program constructs. We used strongly-typed GP-based evolutionary framework for automatic generation of planning logic for blocking the advancement of a computer-driven intruder boat toward a valuable target. Our results show that a genetic programming based synthesis framework is capable of generating decision trees expressing useful logic for blocking the advancements of an enemy boat.
Control of Air Fuel Ratio in SI Engine Using Optimization
Authors: Amini Ali , Mirzaei Mehdi , Khoshbakhti Saray Rahim
Published: January 2011

The air fuel ratio (AFR) control is one of the effective methods to reduce emission and fuel consumption in spark ignition (SI) engines. Due to the hard nonlinearities existing in the engine dynamics model, a nonlinear controller should be designed for AFR control. In this Paper, an optimization-based nonlinear control law is developed for injected fuel mass flow to maintain AFR in the stoichiometric value. Simulation results show that the AFR in the controlled system is very close to the desired value, unlike the uncontrolled system in which the AFR has intensive fluctuations.
Vibration Analysis of Rectangular Functionally Graded Plate Bonded With PZT5 Sensor/Actuator
Authors: Kargarnovin M. H. , Viliani N. S.
Published: January 2011

The vibration of FG plate embedded with PZT5 rectangular patches on the top and/or the bottom surface(s) as actuators/sensors is investigated. Based on the classical laminated plate theory, the governing differential equations of motion are derived under a variable electric charge. The equation of motion for PZT5 patch is obtained and solved. The effect of feedback gain and FGM volume fraction exponent on the plate frequency and its deflection are studied. It is noticed that increasing the feedback gain leads to the reduction of frequency and displacement. Moreover, by increasing the value of the FGM volume fraction exponent the resonant frequency decreases.
Development of Inverse Receptance Coupling Method for Prediction of Milling Dynamics
Authors: Rezaei M. M. , Movahhedy M. R. , Ahmadian M. T. , Moradi H.
Published: January 2011

Receptance coupling substructure analysis (RCSA) is extensively used to determine the dynamic response of milling tool at its tip for the purpose of prediction of machining stability. A major challenge in using this approach is the proper modelling of the joint between the substructures and determination of its parameters. In this paper, an inverse RCSA is developed for experimental extraction of tool-holder frequency response function (FRF) including joint parameters. The accuracy and efficiency of this method is evaluated through an analytical investigation. It is shown that the extracted holder FRF can provide a highly accurate prediction of the tool tip FRF. The developed method is used in prediction of tool tip FRF with different values of the tool overhang. The proposed approach is validated through experimental validation.
On Brushless Motors Continuous Duty Power Rate
Authors: Giberti Hermes , Cinquemani Simone
Published: January 2011

The “continuous duty power rate” of a brushless motor is a coefficient that characterizes its ability to accelerate a load. For this reason it is also called “accelerating factor” and playes a considerable role in the choice of the motor to be used in an automatic machine. This work is focused on the analysis of this parameter, defined for each motor as the ratio between the square of the motor nominal torque and its momentum of inertia: it is exclusively defined by parameters related to the motor and, therefore, it does not depend on the machine task. The research is carried out through a database containing the main electromechanical features of some commercial motors and their “accelerating factors”. Using the collected information, related to more than 300 brushless motors, some graphs are produced showing how motors having the same size can have different accelerating factors or, conversely, how same accelerating factors can be obtained through different electro-mechanical design.
The Generalized Jacobian Matrix and the Manipulators Kinetostatic Properties
Authors: Cinquemani Simone , Giberti Hermes , Legnani Giovanni
Published: January 2011

Manipulator kinetostatic performances are usually investigated considering only the geometrical structure of the robot, neglecting the effect of the drive system. In some circumstances this approach may leads to errors and mistakes. This may happen if the actuators are not identical to each other or when the employed transmission ratio are not identical and/or not constant. The paper introduces the so called “Generalized Jacobian Matrix” obtained identifying an appropriate matrix, generally diagonal, defined in order to: 1. properly weigh the different contributions of speed and force of each actuator. 2. describe the possible non-homogeneous behaviour of the drive system that depends on the configuration achieved by the robot. Theoretical analysis is supported by examples highlighting some of the most common mistakes done in the evaluation of a manipulator kinetostatic properties and how they can be avoided using the generalized jacobian matrix.
A Method for the Calculation of Friction Damping in Blade Root Joints
Authors: Zucca Stefano , Firrone Christian M. , Gola Muzio
Published: January 2011

In turbomachinery, the complete detuning of turbine blades in order to avoid high cycle fatigue damage due to resonant vibration is often unfeasible due to the high modal density of bladed disks. To obtain reliable predictions of resonant stress levels of turbine blades, accurate modelling of friction damping is mandatory. One of the most common sources of friction damping in turbine blades is the blade root, where energy is dissipated by friction due to microslip between the blade and the disk contact surfaces held in contact by the centrifugal force acting on the blade. In this paper a method is presented to compute the friction forces occurring at blade root joints and to evaluate their effect on the blade dynamics. The method is based on an upgraded version of the state-of-the-art contact model, currently used for the non-linear dynamic analysis of turbine blades. The upgraded contact model is implemented in a numerical solver based on the harmonic balance method able to compute the steady-state dynamic response of turbine blades. The proposed method allows solving the static and the dynamic balance equations of the blade and of the disk, without any preliminary static analysis to compute the static loads acting at the contact interfaces.
The Two Phase Jet Use for Surroundings Changes in Semi-Open Space
Authors: Chisacof Alexandru , Panaitescu Valeriu , Pavel Dragos¸ , Poenaru Mihai
Published: January 2011

The paper presents the theoretical and experimental aspects concerning the droplet evaporation processes from the liquid jet, sprayed in an air vapour mixture. From the particularities of the transfer phenomena involved in the droplet evaporation, the lifetime evolution of this, as a function of liquid temperature, its dimension and the surroundings humidity, is displayed. The surroundings consist in a semi-open room in which we may control the entry of the fresh air. Based on these theoretical approaches the test bench was developed. The aspects regarding the experimental tests are mentioned as the jet development followed by the evaporation quality. The experimental diagrams concerning the chart of temperature and humidity inside and near the two-phase jet are shown. The practical values of the measured parameters allow us to use the jet device with a warm liquid in the extinguish system. The tests were realised with various liquid temperature for the gaseous hydrocarbon flame. From the experiment it was observed that the liquid phase in contact with the flame evaporates instantaneously forming the superheated vapour. Consequently, the vapour huge volume generated on this way will decrease the oxygen concentration in the mixture, which may fall it under the ignition limit. On the other hand, the surrounding temperature reduces due to the heat absorption during the liquid evaporation. These two phenomena, which act on the flame, rise the extinguish efficiency of the two-phase jet.
Improvement of Cyclic Strength of Carbon Steel by Various Surface Treatments
Authors: Ciuplys Antanas
Published: January 2011

Fatigue strength is one of the most important mechanical properties. Durability and reliability of car parts are often defined by their fatigue strength, since most of them are loaded with dynamic, repeating or variable loads and the main type of failure is metal fatigue. Various surface hardening methods have a huge impact on fatigue strength of structural materials. The choice of surface processing method is determined by properties and microstructure of a material, as well as the purpose and working conditions of part’s material. Very often the optimum processing is a combination of several methods, which enables to obtain the required properties (high fatigue strength, wear, etc.). The impact of several combined surfaces processing on the fatigue strength of carbon steel samples is investigated in the work. The surface was hardened using different processing combinations: by hardening with high frequency electricity currents, rolling by rollers, heating and cooling under different temperatures. Experimentally it is proved that thermal treatment of plastically deformed carbon steel significantly increases fatigue strength. Experiments showed that after surface hardening with the given regimes, the microstructure and residual stresses are formed in such way that fatigue crack begins to grow under the hardened sample surface.
Characterization of Two Types of Stainless Steels Recommended for Manufacturing Brine Recirculation Pumps
Authors: Abuzeid O. A. , Aljoboury A. I. , Mourad A.-H. I. , Alawar A. , Abou Zour M.
Published: January 2011

In earlier works, characterization and stress corrosion cracking of casings of brine recirculation pumps, used in desalination plants, had been investigated. These casings which were manufactured from two types of Ni resist ductile irons have been reported to show different service lives. Material selection of casings is believed to be one of possible factors to extend the service life of these pumps. Two types of stainless steels; UNS S31603 and UNS S32750 have been recommended as substitutes to Ni resist ductile irons. In this work, mechanical, metallurgical, and electrochemical tests have been conducted on as received samples, made of these two types of stainless steels. Results have shown considerable higher yield and tensile strengths and corrosion resistance for the UNS S32750 over the UNS S31603. Results have also shown reproduced pitting behavior illustrated by measured pitting potentials and visual observations for UNS S31603 samples. UNS S32750 samples have shown no signs of pitting.
Sensor Fusion for Attitude and Bias Estimation for a VTOL UAV
Authors: Metni Najib A.
Published: January 2011

In this paper, a nonlinear complementary filter is presented to estimate the attitude of a Vertical Take Off and Landing Unmanned Aerial Vehicle (VTOL UAV). The measurements are taken from a low-cost IMU (Inertial Measurement Unit) which consists of 3-axis accelerometers, 3-axis gyroscopes and 3-axis magnetometers. From the proposed estimators, the full orientation matrix R will be retrieved. The proposed observers will estimate the instantaneous quaternions as well as the gyroscope bias. This representation of orientation by the rotation matrix and quaternions allows overcoming the problem of singularities that appear in local parametrization such as Euler angles. Therefore, both estimators may be used to describe any kind of 3-D motion. Convergence of the two observers is theoretically proved and simulations are conducted taking data from a real platform in hovering flight conditions.