bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inverse Dynamic Simulation of a Hydraulic Drive With Modelica
Authors: Saad Joseph , Liermann Matthias 
Published: April 2014

Inverse dynamic simulation of hydraulic drives is helpful in early design stages of hydraulic machines to answer the question whether the drive can meet dynamic load requirements and at the same time to predict the energy consumption for required load cycles. While a forward simulation of the hydraulic drive needs an implementation of the controller which generates the control input as a function of the control error, the inverse dynamic simulation can be implemented without control. This is because the required motion is simply defined as a constraint and therefore the control error is always zero.
This paper surveys examples of successful use of inverse dynamic simulation in engineering. We use the example of a hydraulic servo-drive to explain the procedure how to generate a state space description of the inverse problem from the given system of differential algebraic equations. Equation based modeling languages such as Modelica lend themselves naturally for inverse simulation because the definitions of which variables of the model are inputs and which are outputs is not made explicit in the model itself.
Evaluation of a New Method for Customer-Orientated Rating of Clutch Systems in Conceptual Hybrid Vehicles
Authors: Brezger Friedrich , Albers Albert 
Published: April 2014

Coming to hybrid vehicles regarding passenger cars there is still no final answer which hybrid topology is the best system for the market. In European countries the focus is clearly set on energy efficiency or rather on carbon dioxide emission and production costs. There are several innovative hybrids available on the market coming with different advantages for the different customers respectively driver types.
Well-known test cycles like the NEDC (Europe), the 10–15 Mode (Japan), the FTP72&FTP75 (USA) do provide an answer to the question of energy efficiency. But it is also known that this information is not necessarily valid for the special customers’ driver behavior.
For the product development process a tool is required to rate the different hybrid topologies and their components as well as their scales. One aspect is efficiency in additional consideration of the customer classes. Along the dimensioning of possible abuse maneuvers the average performance is important.
In this paper a user-friendly tool for measuring driving data is introduced in order to investigate its sufficiency to evaluate different driver behaviors. This tool uses an OBD-to-Bluetooth-device in combination with a smartphone with GPS. The advantage of this devices compared with a conventional autobox is its low cost and its simple use for all kinds of customers. This fast gained data is processed using probability density functions to create customer classes and representative reference cycles. In a second step a generic hybrid topology with an operation strategy is introduced due to include a detailed clutch system model. This clutch system model has a high fidelity regarding its drag torque behavior. The influence of little improvements at specific operating points on the drag torque will be evaluated. As a result the utility analyses show the efficiency improvement concerning the different driver classes. Thereby a sustained recommendation on further efforts for clutch optimization and its target characteristics can be proposed.
Modeling and Analysis of the Performance of a Parabolic Trough Solar Concentrator System
Authors: Hammad M. , Al-Qtiemat A. , Alshqirate A. 
Published: April 2014

The increasing fossil fuel costs have led the world to use the clean and naturally available energy from the sun to produce electric power.
Parabolic trough technology is nowadays the most extended solar system for electricity production or steam generation for industrial processes. It is the most proven, lowest cost and large-scale solar power technology available today. It is basically composed of a concentrator collector field which converts solar irradiation into thermal energy that will be used as input for a Rankine power cycle. In such plants, a storage system can be implemented in order to increase plant production.
This work aimed to conclude with a simulation model of a solar thermal power plant using a parabol solar concentrator. The Euro Trough (ET) Concentrator was used as case study. MATLAB software was used for the analysis and performance evaluation. Different working fluids were used in the simulation which were: Pressurized water, Boiling water and Oil (Therminol-VP1).
It was found that using water (pressurized or boiling) in the receiver tube is better than the Therminol-VP1 oil.
And the pressurized water has the highest value of efficiency compared to the boiling water and Therminol-VP1 oil. The oil using system presented the highest energy losses system, and the lowest efficiencies. The ET performance was tested at different places in Jordan, and the distribution of direct solar irradiance at different days around the year was calculate and exhibited for Ma’an city as a case study. A comparison between simulated results and that found in literature were carried out with observed good conformity.
Observation and Evaluation of Scratch Damage Characteristics of Injection Molded, Rubber Toughened Poly(Methylmethacrylate)
Authors: An Jihun , Kang Byoung-Hyun , Choi Byoung-Ho , Kim Hyoung-Jun 
Published: April 2014

Poly(methylmethacrylate) (PMMA) is one of popular engineering polymers for many engineering applications such as glass substitutes, medical applications, electronic goods, optical fibers, laser disk optical media and so on. PMMA is a lightweight material with excellent optical properties and balanced mechanical properties. However, PMMA is commonly blended with various functional fillers, and rubber particles are one of them to improve the low impact toughness of unfilled PMMA comparing with other engineering polymers such as polycarbonate (PC), acrylonitrile-butadiene-styrene (ABS) copolymer and so on. PMMA is generally used to make exterior of a commercial product, so scratch characteristics of PMMA is very important in terms of the aesthetic point of view.
In this paper, rubber toughened PMMA plates are prepared by injection molding, and static and progressive scratch tests are performed. Samples are prepared by various injection molding conditions, and two orientations (machine direction and transverse direction) of the injection molded plate are considered for scratch tests. Three scratch damage mechanism stages, i.e. mar/ploughing, whitening and cutting stages, are identified by observing the scratch damages and two critical loads to define the variation of scratch damage mechanisms are recorded to evaluate the scratch resistance of rubber toughened PMMA samples. Scratch damage characteristics are examined by various microscopy techniques such as optical microscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, optical profiler and so on. It is clearly observed that scratch damage characteristics of rubber toughened PMMA are changed sensitively for various test conditions due to rubber particles, so it can be known that the mold design should be carefully optimized to improve scratch characteristics of injection molded rubber toughened PMMA product.
Test Rig Design to Explore Water Droplet Behavior in a Four Stage Axial Compressor
Authors: Clauss S. , Schnitzler J. P. , Barabas B. , Nagabhushan P. S. , Benra F. K. , Dohmen H. J. 
Published: April 2014

The efficiency of gas turbine cycles can be enhanced by many applications and combinations according to the choice of the thermodynamic cycle. Gas turbine cycles which operate with humid air and water injection at different locations of the compressor are in the focus of present thermodynamic analysis and experimental research. Reasoned by their high potential in efficiency and power output augmentation, they have been implemented on many industrial gas turbines. The evaporation process of water droplets, especially at high temperature and pressure levels has been recently investigated with the laser based measurement technique Phase Doppler Particle Analyzer (PDPA) in detail in a stationary test rig at the University of Duisburg-Essen. The focus of these investigations was on the analysis of the evaporation process in a free stream or cross flow without droplet wall interaction [1–5]. In this paper the development of a novel four stage axial compressor test rig which is designed for water injection will be introduced and results of numerical investigations will be presented. This test rig has been designed to adopt the results from the stationary test rig to a real compressor.
The first part of the paper deals with the mechanical and aerothermodynamic design of the test rig. Certain design parameters, the optical access for the PDPA measurements and a comparison between numerical and experimental results without water injection are outlined.
In the second part of the paper, first comparative results from numerical investigations of the compressor performance in dry and wet compression operating conditions are presented. Furthermore, numerical results for droplet wall interaction in the four stage axial compressor are shown. This analysis outlines the need for further experimental research in the future to validate numerical methods with accurate droplet wall interaction behavior in turbomachines.
Trigonometric Collocation for Computation of Steady State Response of a Cracked Beam
Authors: Bakeer Bakeer , Shiryayev Oleg 
Published: April 2014

Development of vibration-based structural health monitoring techniques requires the use of various computational methods to predict dynamic responses of damaged structures. The method described in this work can be used for prediction of steady state harmonic responses for structures with fatigue cracks and may have several advantages over alternative techniques.
The method appears to be relatively easy to implement and computationally inexpensive. The steady state response of the system at a given number of time points distributed over one vibration period is represented in terms of Fourier series containing higher frequency harmonics. Equations of motion are formulated in the form that allows for easy computation of Fourier coefficients for all terms in the series. Iterative procedure is used for determining the time of stiffness change in order to capture bilinear dynamic behavior. We present results of initial investigation by applying the method to a model of a cantilever beam with a crack.
Optimized Multi-Floor Throughflow Micro Heat Exchangers
Authors: Abdoli Abas , Dulikravich George S. 
Published: April 2014

Multi-floor networks of straight-through liquid cooled microchannels have been investigated by performing conjugate heat transfer in a silicon substrate of size 15×15×1 mm. Two-floor and three-floor cooling configurations were analyzed with different numbers of microchannels on each floor, different diameters of the channels, and different clustering among the floors. Thickness of substrate was calculated based on number of floors, diameter of floors and vertical clustering. Direction of microchannels on each floor changes by 90 degrees from the previous floor. Direction of flow in each microchannel is opposite of the flow direction in its neighbor channels.
Conjugate heat transfer analysis was performed by developing a software package which uses quasi-1D thermo-fluid analysis and a 3D steady heat conduction analysis. These two solvers are coupled through their common boundaries representing surfaces of the cooling microchannels. Using quasi-1D solver significantly decreases overall computing time and its results are in good agreement with 3D Navier-Stokes equations solver for these types of application.
Multi-objective optimization with modeFRONTIER software was performed using response surface approximations and genetic algorithm. Maximizing total amount of heat removed, minimizing coolant pressure drop, minimizing maximum temperature on the hot surface, and minimizing non-uniformity of temperature on the hot surface were four simultaneous objectives of the optimization. Pareto-optimal solutions demonstrate that thermal loads of 800 W cm−2 can be effectively managed with such multi-floor microchannel cooling networks. Two-floor microchannel configuration was also simulated with 1,000 W cm−2 uniform thermal load and shown to be feasible.
Integral Effect Test on Operational Performance of the PAFS (Passive Auxiliary Feedwater System) for a SGTR (Steam Generator Tube Rupture) Accident
Authors: Park Yusun , Bae Byoung-Uhn , Kim Seok , Cho Yun-Je , Kang Kyoung-Ho 
Published: April 2014

The PAFS is one of the advanced safety features adopted in the APR+ (Advanced Power Reactor Plus) which is intended to completely replace a conventional active auxiliary feedwater system. The PAFS cools down the steam generator secondary side and eventually removes the decay heat from the reactor core by adopting a natural convection mechanism; i.e., condensing steam in nearly-horizontal U-tubes submerged inside the PCCT (Passive Condensation Cooling Tank). With an aim of verifying the operational performance of the PAFS, the experimental program of an integral effect test is in progress at KAERI (Korea Atomic Energy Research Institute). The test facility, ATLAS-PAFS was constructed to experimentally investigate the thermal hydraulic behavior in the primary and secondary systems of the APR+ during a transient when the PAFS is actuated.
Since the ATLAS-PAFS facility simulates a single train of the PAFS, the anticipated accident scenarios in the experiment include FLB (Feedwater Line Break), MSLB (Main Steam Line Break), and SGTR (Steam Generator Tube Rupture). Among them, SGTR was considered as one of the design basis accidents having a significant impact on safety in a viewpoint of radiological release. Therefore, the SGTR test was determined to be the integral effect test item in the frame of the ATLAS-PAFS experimental program.
In this study, the PAFS-SGTR-HL-02 test was performed to simulate a double-ended rupture of a single U-tube in the hot side of the steam generator of the APR+. The three-level scaling methodology was taken into account to determine the test conditions of the steady-state and the transient. The pressures and temperatures of the system and the data related to the PAFS operation were collected with the measurement of the break flow.
The initial steady-state conditions and the sequence of event of SGTR scenario for the APR+ were successfully simulated with the ATLAS-PAFS facility. And it was shown that the pressure and the temperature of the primary system were continuously decreased during the heat removal by the PAFS operation. The water pool in the PCCT was heated up to the saturation condition and the evaporation of the water made a decrease of the PCCT water level.
It could be concluded from the present experimental result that the APR+ has the capability of coping with the hypothetical SGTR scenario with adopting the PAFS and the proper set-points of its operation.
Direct Transmission Loss Calculation of Simplified Muffler Configurations Using a Lattice-Boltzmann Method
Authors: Mann Adrien , Pérot Franck 
Published: April 2014

Lattice-Boltzmann Method (LBM) is broadly used for the simulation of aeroacoustics problems. This time-domain CFD/CAA approach is transient, explicit and compressible and offers an accurate and efficient solution to simultaneously resolve turbulent flows and their corresponding flow-induced noise radiation. Some examples of applications are ground transportation wind-noise problems, buffeting, Heating, Ventilation, and Air Conditioning (HVAC), fan noise, etc. As shown in previous studies, LBM can also be used to accurately handle linear acoustics problems if the source of noise is not a flow but a simple acoustic source. This set of capabilities makes LBM a suitable candidate for evaluating the acoustics performances of exhaust systems and mufflers.
Compared to other traditional acoustics methods, LBM presents the advantage to skip tedious volume meshing operations since the mesh generation is fully automatic. Furthermore, considering that all geometrical details are included in the simulation domain and that LBM is explicit, high frequencies mechanisms up to 10–20 kHz can be captured. The upper frequency limit is indeed solely driven by the spatial resolution used to discretize the system.
In this paper, three academic 3-D geometries representative of production muffler systems are studied. Transmission Loss (TL) measurements are performed on three configurations and these experiments are reproduced numerically with LBM.
The experimental setup is described in a first part and the numerical details are given in a second part and third part. In particular, the method used to calculate the TL in the simulation and the convergence of the results with respect to the spatial resolution are shown. In a third part, the simulations are compared to the TL measurements and a numerical investigation of the effect of geometry details on the simulated results is proposed. This study highlights the sensitivity of acoustics measurements to geometry details.
Robustness Analysis of Two-Speed Electric Vehicles
Authors: Roser Holger , Walker Paul D. , Zhang Nong 
Published: April 2014

This paper presents the findings of a theoretical analysis of a two-speed Dual-Clutch Transmission (DCT) for electric vehicle applications. Electric drives incorporating DCTs can offer improved driving economy and range, acceleration and climbing gradeability, with potentially smaller electric motors (EMs). Overall powertrain performance is simulated with different standard driving cycles, including urban, extra-urban, and constant speed driving, and different EM power ratings. Simulation results are compared against equivalent single-speed powertrain, including a conceptual evaluation of powertrain bulk, weight and cost.
Despite added complexity of including a DCT, the simulated driving range is increased by shifting the operating region of the electric motor to greater efficiency regions. This is shown to be more predominant during high-speed driving. In addition, satisfactory drive performance can be achieved with smaller EMs, compensating for added transmission bulk, weight and cost. An outline of further areas of two-speed electric drive research and applications conclude this paper.
Mechanical and Thermal Engineering for High Temperature Fuel Cell Systems
Authors: Salminen Pauli , Ahlgren Esa , Kuosmanen Petri 
Published: April 2014

Solid Oxide Fuel Cell (SOFC) systems achieve high electrical efficiency and can utilize many types of fuels such as methanol or biogas. These systems operate at high temperatures up to 600–1000 °C. Due to high temperatures, mechanical engineering must be combined with thermal engineering through the design work.
System design for SOFC systems should take into account several functions such as mechanical support of components, thermal insulation, instrumentation, compensation for thermal expansion and heat recovery as well as conduction of gases through channels, piping or open cavities. One should note that many of these functions have strong interactions and cannot be designed without an effect on the system as a whole. When a system is designed to fulfill all the expectations, it will have a compact size, good thermal properties, small pressure losses and good overall performance together with a competitive price, long system lifetime and easy maintenance.
This article aims to improve the mechanical structure of SOFC systems. In addition, our aim is to give sophisticated recommendations for a system design. To achieve this, we have used systematic concept development tools and methodologies to investigate the interactions and relative importance of system requirements and functions.
Our key result from this study is that engineers must use a holistic approach when designing a high temperature system with strong interactions between system functions and components. Contrary to our former expectations, these systems could not be designed well by methods that are based on reductionism. In practice, this means that thermal engineering must be utilized from the very beginning. Thermal insulation concept should be selected during the first design steps since this has a great effect on system layout. Mechanical engineering is needed in system layout design in order to solve problems related to the thermal expansion and support of components. Combined thermal and structural analysis utilizing finite element methods can be used to develop or optimize mechanical key components and system layout. The best results can be achieved by using a holistic approach during the design process.
In addition, it is beneficial to keep the system as simple and compact as possible. To achieve this, the integration of functions and components must be increased. Thus, SOFC system performance is greatly dependent on system design, not only of its components alone. Findings obtained from this study can be used by researchers designing experimental apparatuses or by companies manufacturing full scale SOFC systems.
An Offline-Signal Processing Algorithm for Combining Superior Excitation Methods for an Ultrasonic Piezo Motor
Authors: Borchert Gunnar , Dröder Klaus , Raatz Annika 
Published: April 2014

Ultrasonic piezomotors have been applied as a drive concept in miniaturized robot systems for many years. They have various beneficial characteristics, such as low costs, high accuracy and velocity. This has been demonstrated, with instance, with APIS, a miniaturized robot developed at the Technische Universität Braunschweig. With the example of APIS, this contribution discusses the challenge of an offline signal processing techniques in order to combine different excitation methods for the piezomotors used in this robot. Since each excitation method influences the motor characteristic in a variety of ways, this research is motivated by desire for an optimal adaptation of certain features to a given trajectory, such as velocity, acceleration, moving direction or step resolution. Thus, our approach is to develop different ways to split a given trajectory into segments with regard to the requirements of the motor. So these segments can be linked to an excitation method which brings about the desired features. To this end, model trajectories are first generated and reasonable excitation methods for the piezomotor are identified and characterized. Key features are velocity, acceleration, moving direction and step resolution. Apart from defining key features, an assessment algorithm has been developed along with suitable weighting criteria. Offline signal algorithm means that the trajectory will be analyzed and that the arrangement of suitable excitation methods will be defined before the motion process starts.
Finally the results, that is, each model signal together with the associated excitation method, are shown and validated. To achieve better results, possibilities for future developments are identified.