bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Fracture Behavior of Flat Braided CFRP Composites Under Tensile Loading With Assistance of SQUID Technique
Authors: Aly-Hassan Mohamed S. , Takai Yuka , Nakai Asami , Hamada Hiroyuki , Shinyama Yohei , Hatsukade Yoshimi , Tanaka Saburo
Published: August 2012

The goal of this research is to provide a sufficient understanding for the damage mechanism of ±45° flat braided CFRP composites under tensile loading based on in-situ macroscopic observations of surface cracking and off-line measurements for the state-of-fibers by Superconducting Quantum Interference Device (SQUID) technique to analyze the effect of the continuously oriented of all braided fiber bundles on the tensile and in-plane shear properties. SQUID technique displays an effective capability in inspection the state-of-fiber failure, whereas the in-situ surface macroscopic observation technique is very useful in observing the surface matrix cracking at different stages of damage. The damage mechanism of uncut-edges and cut-edges of ±45° flat braided CFRP composites are identified adequately by the above-mentioned experimental procedure. The cut-edges ±45° flat braided CFRP composites exhibit a pure shear damage mechanism associated with large shear deformation and no significant fiber failure, while the uncut-edges ±45° flat braided CFRP composites exhibit a slight fiber scissoring mechanism followed by a partially fiber failure. The enhancement of the tensile and in-plane strengths of the uncut-edges ±45° flat braided CFRP composites by about 60% higher than those of the cut-edges ±45° flat braided CFRP composites achieves not only by the effect of the continuously oriented carbon fibers at the edges but also by the effect of re-orientation of braiding fiber bundles with smaller angle than the original ±45° braiding angle of the fabricated composites, or so called fiber scissoring mechanism in composites.
Thermodynamic Analysis of a Multi-Fueled Single Cylinder SI Engine
Authors: Haq M. Z. , Mohiuddin M. R.
Published: August 2012

The paper presents a thermodynamic analysis of a single cylinder four-stroke spark-ignition (SI) engine fuelled by four fuels namely iso-octane, methane, methanol and hydrogen. In SI engines, due to phenomena like ignition delay and finite flame speed manifested by the fuels, the heat addition process is not instantaneous, and hence ‘Weibe function’ is used to address the realistic heat release scenario of the engine. Empirical correlations are used to predict the heat loss from the engine cylinder. Physical states and chemical properties of gaseous species present inside the cylinder are determined using first and second law of thermodynamics, chemical kinetics, JANAF thermodynamic data-base and NASA polynomials. The model is implemented in FORTRAN 95 using standard numerical routines and some simulation results are validated against data available in literature. The second law of thermodynamics is applied to estimate the change of exergy i.e. the work potential or quality of the in-cylinder mixture undergoing various phases to complete the cycle. Results indicate that, around 4 to 24% of exergy initially possessed by the in-cylinder mixture is reduced during combustion and about 26 to 42% is left unused and exhausted to the atmosphere.
Bayesian Update With Fuzzy Information
Authors: Beer Michael , Stein Matthias
Published: August 2012

A realistic quantification of all input information is a basic requirement in order to obtain useful results from engineering analyses. The concept of quantification and the associated uncertainty model have to be selected in agreement with the amount and quality of the available information. For inconsistent information, a distinction between probabilistic and non-probabilistic characteristics is beneficial. In this distinction, uncertainty refers to probabilistic characteristics and non-probabilistic characteristics are summarized as imprecision. When uncertainty and imprecision occur simultaneously, the uncertainty model fuzzy randomness appears useful. In this paper, the fuzzy probabilistic model is utilized in a Bayesian approach to take account of imprecision in data and in prior expert knowledge. The propagation of imprecision and uncertainty is investigated for selected cases. The Bayesian approach extended to inconsistent information is demonstrated by means of an example.
Enhanced Steering System Inspection for Improving Road Safety
Authors: Pe´rez-Rey Manuel , Garci´a-Pozuelo Daniel , Boada M. J. L. , Lo´pez Vicente Di´az
Published: August 2012

Three new criteria have been developed with the purpose of improving road safety, through an enhanced wheel alignment inspection in the context of the Periodic Motor Vehicle Inspection (PMVI). Nowadays, the result of the inspection in Spain is not determined directly from an objective measurement. It depends greatly on the inspector criterion. The three developed criteria provide the inspectors with an objective procedure, based on the measuring device that is nowadays installed in the PMVI stations: the sideslip tester. The first proposed criterion checks if the toe-in angle is set according to the manufacturer’s specifications, using a model that has been specifically developed to estimate this angle from the sideslip measurement. The second one evaluates if there is an excessive permanent side force when driving in straight line, thanks to a model expressly developed for this purpose. A third criterion establishes a limit for the sideslip measurement, common for all the vehicles, with a non-symmetrical range from the zero sideslip. An extensive program of validation tests has been carried out for the three proposed methods. According to them, the third proposal has been chosen as the preferred one. Previously, a comprehensive study of the sideslip measurement fundamentals and the different factors that may have an influence on the results was done.
Wicking Performance of Two-Dimensional Bi-Porous Wicks
Authors: Byon Chan , Kim Sung Jin
Published: August 2012

Micro-post wick is a promising candidate for high-heat-flux applications due to its compatibility, high conductivity and permeability. In this study, the capillary performances of micro-post wicks of various configurations are investigated. Five types of micro-post wicks which have dual-scale pore structure (parallel, quadratic, hexagonal, diamond, and periodic) are considered and the capillary performance is compared with micro-post wicks of uniform array. The capillary performance of wicks is characterized using capillary rate of rise experiments and numerical simulations that accounts for the finite curvatures of liquid menisci. From the experimental and numerical studies, it is shown that the capillary performance of multi-scale wicks is higher than that of mono-scale wicks significantly (by 35% for parallel array, 31% for quadratic array). The capillary performance parameter is shown to be primarily a function of solid fraction and decreases approximately linearly with solid fraction, regardless of the array type. The experiment, associated with visual observation, indicates that the capillary performance is degraded when the pore size is too large or the solid fraction is too small.
Simulation and Interoperability in the Planning Phase of Production Processes
Authors: Schilberg Daniel , Meisen Tobias , Reinhard Rudolf , Jeschke Sabina
Published: August 2012

Interoperability is a progressive issue in the development of holistic production process simulations that are based on stand-alone simulation interconnections. In order to tackle the problem of missing interoperability, the standardization of simulation and model interfaces and transfer protocols can be taken into account. This procedure is endorsed by many organistaions like DIN ISO, IEEE, ASME or SISO and one of the most effective proceedings if a new simulation is developed and if the source code of the used simulations is available as well as changeable. However, as most simulations for a holistic production simulation already exist and as those simulations are usually isolated, high precisely solutions, which have no common interfaces for interconnection, a different approach is needed. The contribution at hand focuses on a framework that provides adaptive interfaces to establish interoperability of stand-alone simulations.
Massively Parallel Computational Fluid Dynamics With Large Eddy Simulation in Complex Geometries
Authors: Duggleby Andrew , Camp Joshua L. , Doron Yuval , Fischer Paul F.
Published: August 2012

To perform complex geometry large eddy simulations in an industrially relevant timeframe, one must reduce the total time to half a day (overnight simulation). Total time includes the time of developing the mesh from the computer-aided design (CAD) model and simulation time. For reducing CAD-to-mesh time, automatic meshing algorithms can generate valid but often non-efficient meshes with often up to an order of magnitude more grid points than a custom-based mesh. These algorithms are acceptable only if paired with high-performance computing (HPC) platforms comprising thousands to millions of cores to significantly reduce computational time. Efficient use of these tools calls for codes that can scale to high processor counts and that can efficiently transport resolved scales over the long distances and times made feasible by HPC. The rapid convergence of high-order discretizations makes them particularly attractive in this context. In this paper we test the combination of automatic hexahedral meshing with a spectral element code for incompressible and low-Mach-number flows, called Nek5000, that has scaled to P >262,000 cores and sustains >70% parallel efficiency with only ≈7000 points/core. For our tests, a simple pipe geometry is used as a basis for comparing with previous fully resolved direct numerical simulations.
An Operations Research Approach to Work-Optimal Trajectories for Redundant Robotic Manipulators
Authors: Steuben John , Brayford Paul , Turner Cameron J.
Published: August 2012

Control of redundant robotic manipulators has proven to be troublesome in the past. Redundant manipulators exhibit more degrees of freedom than there are constraints on their pose. As a result the robot’s kinematics are non-deterministic, and an infinite number of robot poses satisfy any given set of constraints. Thus there are an infinite number of paths that a robot may take whilst following a trajectory planned in Cartesian space (as opposed to joint space). We present a trajectory following method for a redundant welding robot with nine degrees of freedom (DOF). A powerful modeling tool widely used in operations research, AMPL, is leveraged to this end. The paths developed for the 9-DOF robot are optimized for minimum energy consumption by the robot motors. We also demonstrate a simulated robot work cell which is used to visualize and demonstrate the paths produced in this manner. Common robotic welding tasks are used to demonstrate the effectiveness of these optimization and visualization tools. We conclude with a discussion of the computational efficiency and limitations of this new method, and highlight several paths forward for this line of research.
Analytical Investigation of Aero-Elastic Behavior of Aircraft Composite Box Wings in Unsteady Compressible Flow
Authors: Farsadi T. , Haddadpour H. , Yuceoglu U.
Published: August 2012

In this study, an anisotropic thin-walled “Composite Box Beam” as the “Wing System” is used to consider the effects of the fiber orientation and the lay-up configuration on the aeroelastic stability and the dynamic response of an aircraft wing. The present “Circumferentially Asymmetric Stiffness Model (CAS)” takes into account a group of non-classical effects; such as the transverse shear, the material anisotropy, warping inhibition, etc. The “Aerodynamic Strip Method” based on “Wagner Functions” in unsteady compressible flow are used to simulate compressible unsteady aerodynamic effects in the “state space” form. In addition, the mass, the stiffness and the damping matrices of the present non-conservative aeroelastic system are formed so that, the “Extended Galerkin’s Method (EGM)” and the “Separation of Variables Method” can be employed. As a result, the coupled and linear “Governing System of Dynamic Equations” are obtained. After then, by transforming matrices into the “state space” and “state vector” forms, the problem under study is finally converted into an “Eigenvalue Problem and Analysis”. Hence, the “flutter” and the “divergence” speeds for various layer configurations with different geometric and material properties and fiber orientations were obtained. Furthermore, by solving the aforementioned equations of motion in the time domain, the aeroelastic responses of the “Composite Box Wing System” for different flight regimes are computed. The present numerical results were compared and are verified with some existing experimental results in the literature. Based on these, some brief but important conclusions are presented.
Development of a Finite Model for Controlling a Mold’s Open/Close Process in an Injection Molding Machine
Authors: Alzoubi M. F. , Abu-Ayyad Ma’moun
Published: August 2012

This paper presents a unique approach for integrating a finite element analysis (FEA) model using a dynamic explicit of Abaqus with a nonlinear process of the mold’s open/close phase in an injection molding machine. This opening/closing phase is considered to have one of the highest impacts on reducing an overall cycle duration since it has no impact on the final part quality. Reducing the overall cycle duration has a big positive impact on productivity and enhancing efficiency of the manufacturing processes of injection molding systems. Therefore, one of the objectives of the injection molding manufacturers is increasing efficiency by reducing the time duration of this phase to a possible minimum. In this work, a 3-dimensional (3D) solid model of the mold, toggle mechanism, and hydraulic cylinder were developed and then superimposed with Abaqus software to animate the motion of the movable part of the mold. The position of the movable part of the mold is traced and used as a controlled variable while the inputted force and initial velocity were considered as the manipulated variables. The innovation of this strategy is that the controller structure uses the nonlinear model to update the process variables at every sampling instant while the closed-loop control is executed. This allows the determination of the plant’s variables resulting in a new set of the controller parameters with every sampling instant.
Investigation of Vehicle Seat With Active Control System to Minimize Vertical Vibrations From Seat to Human Body
Authors: Ota S. , Nishiyama S.
Published: August 2012

This paper describes an active control system intended to minimize the vertical vibrations transferred from the seat to the human body in a vehicle. This system controls mechanical properties such as the spring constants and damping coefficients of each part of the vehicle seat by using an optimization algorithm that comprises vibration analysis and an optimization method. To examine the feasibility of the optimization algorithm, we designed a vibration model for the seat–occupant system and calculated the reduction in vibration due to the algorithm by numerical analysis. The mechanical properties of the back and front side of the seat were controlled with reference to the standard condition in the range of 1/1.5–1.5 times, 1/2–2 times, and 1/4–4 times. These results suggest that the percentage reduction in vibration for the head—a sensitive part of the human body—because of acceleration in the frequency range of 4–8 Hz was 36%–52%, 40%–63%, and 55%–76%, respectively. In summary, the proposed algorithm successfully reduced vibrations from the seat to the human body in a vehicle.
A Polyimide Micro Heat Exchanger With a Suspended 3D Parallel Channel Structure for Cryogenic Application
Authors: Wang Yunda , Lewis Ryan , Lin M.-H. , Yan Yiwei , Radebaugh Ray , Bradley Peter , Lee Y. C.
Published: August 2012

A heat exchanger (HX) plays an important role in many cryogenic systems. This paper demonstrates a fully integrated fabrication process to make a novel monolithic polyimide micro heat exchanger. This heat exchanger consists of two parallel rectangular polyimide channels stacked on top of each other with a typical dimension of 15 mm × 4 mm × 90 μm. The stacked channels were suspended on top of a silicon substrate as one of the ends anchored. The fabrication is based on surface micro-machining technology using electroplated copper as the sacrificial layers and polyimide as the structural material. Preliminary testing results demonstrated that the polyimide HX can sustain a cryogenic temperature lower than 77 K and is able to hold a pressure larger than 1 MPa. The pressure drop across the channel was found to increase parabolically with the flow-rate through it, as assessed with standard nitrogen at room temperature.
Design Research of Micro Experiment-Rig of Combined Power Plant
Authors: Xie Chunling , Wang Zhitao
Published: August 2012

Diesel engine power plant, gas turbine power plant and steam turbine power plant are in common use in ship main propulsion power. These power plants have each advantage and disadvantage at mass, size, most high-power, economic ability, and maneuverability. But any single power is difficult to meet the requirement of improving the ships’ tactical performance, speed and maneuverability. In developing history of ship propulsion system, in order to solve the contradiction between full speed high-power and cruise economic ability, combined power plant form can change the performance of simple plant, which collected the advantage of all kinds of power plants[1]. Here combined power plant form is two or more same or not the same type engine combine used or trade off. The combined power plant can not only supply total power for ships when cruising, but also be more economical. So this plant is used widely. This paper designs a multi-module experiment-rig and introduces its composition, working principle and disposition scheme, and designed survey and control System. The micro experiment-rig control system introduced SIMATIC S 7-400 of Siemens Inc. This system can simple the structure and reduce much interface assembly. The bounds of master and industrial controller, continuous and logical system, concentrated and distributed system can be overcome. The surveillance system used the S7-300 PLC of Siemens Inc. This system can analyze and process the data, display by the Real-time report forms, the curves of changed trend, and dynamic menu. Then surveillance and analytic report was created. So the surveillance system of micro experiment-rig supplied data platform for analyzing the running characteristic combined power plant.
“Cash for Clunkers”: A Historical Analysis of the U.S. Quest for Independence From Foreign Oil
Authors: Kreith Frank , West Ron E.
Published: August 2012

One of the most ambitious efforts to improve the efficiency of the American ground transportation system was the Consumer Assistance to Recycle and Save (CARS) Act of 2009, commonly referred to as the “Cash for Clunkers” program. This Act directed the Secretary of Transportation to establish a program from which owners of vehicles could receive credit for trading in their vehicles and purchasing a more fuel efficient vehicle. The credit amount was either $3,500 or $4,500, depending on the amount of improved fuel efficiency. The Act initially appropriated $1 billion for the program, but because of the enormous public response, Congress appropriated an additional $2 billion to extend the program, tripling the potential number of transactions originally expected. This article summarizes previous efforts to reduce the U.S. dependence on foreign oil import. It then analyzes the effect of the CARS Act on the improvement in vehicle efficiency, the reduction in national gasoline consumption, the economic benefits and/or losses to the consumer, the energy return on energy investment (EROI) for the vehicles purchased under this Act, and environmental benefits. It also compares the CARS Act with previous initiatives to improve the CAFE standard. Finally, recommendations are made for improving the mileage of the American automobile fleet and reducing the amount and cost of imported oil.
Thermal Conductivity Estimation of Nano Graphene Using Equilibrium Molecular Dynamics With Andersen and Berendsen Thermostats
Authors: Khadem Masoud H. , Wemhoff Aaron P.
Published: August 2012

The impact of the temperature control method on the thermal conductivity of a small sheet of graphene is studied. Equilibrium Molecular Dynamics (EMD) simulations are used to evaluate the heat current fluctuations and thermal conductivity calculations. The Tersoff potential model is used to determine the covalent interactions between carbon atoms of the graphene’s honeycomb structure. Green-Kubo relations are employed to estimate thermal conductivity values. Andersen and Berendsen thermostats are separately utilized to obtain a desired temperature for the canonical (NVT) ensemble. The influence of the chosen thermostat on the estimated thermal conductivity found to be significant. The wide range of computational and experimental results shows that further work is required to confidently determine the thermal conductivity of this material.
Articulated Mechanism Design and Kinematics for Natural Orifice Translumenal Endoscopic Surgery Robot
Authors: Chin Wei Jian , Nelson Carl A. , Seow Chi Min
Published: August 2012

Natural orifice translumenal endoscopic surgery (NOTES) has reduced the invasiveness of surgery by eliminating external incisions on the patient. With this type of procedure, recovery time is drastically shortened, cosmetics are improved, and infections and pain are greatly reduced. For NOTES procedures to be successfully performed, a flexible endoscope or similar instrument is important for passing orifice flexures. However, technological deficiencies like poor angulations of surgical instruments introduced through working channels in flexible endoscopes, the lack of scope fixation, and lack of scope stiffening are technological barriers which prevent NOTES from being widely accepted in human surgeries. A novel multifunctional robot with an articulated drive mechanism for NOTES has been developed. The steerable articulating drive mechanism is connected to the robotic end effector to guide the robot and navigate through a natural orifice. The design process for the articulating drive mechanism and engineering analysis are discussed in this paper. Workspace of the drive mechanism with and without a translational insertion degree of freedom is presented in detail. The kinematics of the drive mechanism is also discussed. Additionally, friction in the spherical joints of the drive mechanism is explored to characterize its influence on the overall shape achieved by the articulation, including the effects of varying the total length in the steering mechanism. The surgeon control console for the drive mechanism is briefly discussed as well. Bench-top testing results are presented as proof of feasibility of the design.
Flow Dynamic Effect in Cake Shape and Resistance in Membrane Filtration
Authors: Giorges Aklilu T. G. , Pierson John A.
Published: August 2012

Membrane filtration is one of the methods for separating targeted material from a fluid stream. Membrane based filtration is applied in many areas of processing to separate and concentrate fluids. However, fouling and film growth at the filter surface is a major problem that causes loss in efficiency. The cake buildup during the filtration process is investigated experimentally to understand the affect of flow dynamics on the cake characteristics, shape and associated resistance. The experiments were conducted without and with shear generated using an impeller operated at various rotational speeds. The results illustrate that indeed the cake shape and character are affected by the flow dynamics that eventually influence filtration resistance. Likewise the filtrate rate and the cake shape significantly affect the flow dynamics. Furthermore, the filtration resistance is not only affected by the thickness of the cake, but also by how the cake is formed. After similar volumes of filtrate, the flux rate of 120 Lm−2hr−1 for 4.4 mm thick and 1.8 g cake is observed for dead-end filtration, while the flux rate of 600 Lm−2hr−1 for 1.1 mm thick and 0.35 g cake where observed with a shearing rate of 630 s−1. Understanding the size and characters of cake buildup is very important to designing a system to overcome the drawbacks associated with membrane fouling. Moreover, developing a technology with the cleaning process that removes or eliminates cake and maintains a reasonable flux for an extended period requires a thorough understanding of the filtration system geometry and flow dynamics.
Liquid Bio-Fuel Production From Non-Food Biomass via High Temperature Steam Electrolysis
Authors: Hawkes G. L. , O’Brien J. E. , McKellar M. G.
Published: August 2012

Two hybrid energy processes that enable production of synthetic liquid fuels that are compatible with the existing conventional liquid transportation fuels infrastructure are presented. Using biomass as a renewable carbon source, and supplemental hydrogen from high-temperature steam electrolysis (HTSE), these two hybrid energy processes have the potential to provide a significant alternative petroleum source that could reduce US dependence on imported oil. The first process discusses a hydropyrolysis unit with hydrogen addition from HTSE. The second process discusses a process named Bio-Syntrolysis. The Bio-Syntrolysis process combines hydrogen from HTSE with CO from an oxygen-blown biomass gasifier that yields syngas to be used as a feedstock for synthesis of liquid transportation fuels via a Fischer-Tropsch process. Conversion of syngas to liquid hydrocarbon fuels, using a biomass-based carbon source, expands the application of renewable energy beyond the grid to include transportation fuels. It can also contribute to grid stability associated with non-dispatchable power generation. The use of supplemental hydrogen from HTSE enables greater than 90% utilization of the biomass carbon content which is about 2.5 times higher than carbon utilization associated with traditional cellulosic ethanol production. If the electrical power source needed for HTSE is based on nuclear or renewable energy, the process is carbon neutral. INL has demonstrated improved biomass processing prior to gasification. Recyclable biomass in the form of crop residue or energy crops would serve as the feedstock for this process. A process model of syngas production using high temperature electrolysis and biomass gasification is presented. Process heat from the biomass gasifier is used to heat steam for the hydrogen production via the high temperature steam electrolysis process. Oxygen produced form the electrolysis process is used to control the oxidation rate in the oxygen-blown biomass gasifier.
A Methodology for Identifying Factors That Contribute to the Sustainability of Bioinspired Engineered Systems
Authors: O’Rourke Julia M. , Seepersad Carolyn C.
Published: August 2012

Within the bodies of living organisms are multitudes of sustainable design solutions that scientists have yet to discover and engineers have yet to master. Living organisms employ novel methods of harvesting energy from ambient sources, producing materials at low temperatures, and optimizing shapes to achieve energy efficiency, among many other sustainability-enhancing techniques. Through sustainable bioinspired design, engineers can apply this body of knowledge to engineered products and systems. In order to do this, a better understanding is needed of the types of sustainability solutions present in biology and readily available to engineers. One approach to this problem is to analyze existing bioinspired designs with an environmental advantage over alternatives and find trends in the types of sustainable solutions present in these designs. The purpose of this paper is to present a methodology for identifying trends embodied in existing, sustainable, bioinspired designs. For this study, a broad and representative list of currently available bioinspired designs was compiled including gecko robots, lotus leaf-inspired self-cleaning surfaces, termite-inspired buildings, and kingfisher-inspired trains. Three criteria were used to determine which designs should be studied in detail: (1) verification that the design was actually bioinspired, (2) evidence that the design is or was physically embodied, either as a functional prototype or as a commercial product, and (3) literature-based demonstration of environmentally beneficial characteristics. Due to time limitations, a fourth criterion was also used: (4) literature-based demonstration of environmentally beneficial characteristics in the use phase of the design; however, the procedure presented is valid for designs offering sustainability advantages in any life cycle phase. The bioinspired designs meeting the selection criteria were analyzed in detail, along with their functionally-equivalent alternatives. The sustainability advantages of the bioinspired designs, relative to their alternatives, were identified using a list of 65 published green design guidelines. This paper presents the methodology for each of these steps, including the benefits and drawbacks. In addition, a detailed explanation is provided for each step using bioinspired examples.
Heat Transfer Distribution of Various Rib Geometries for Developing Flow at High Rotation Numbers
Authors: Lamont Justin A. , Ekkad Srinath V. , Alvin Mary Anne
Published: August 2012

The Coriolis force and centrifugal buoyancy have a significant effect on the cooling performance for rotating internal serpentine coolant channels in gas turbine blades. As coolant flow in rotation is highly complex, detailed knowledge of the heat transfer over a surface will greatly enhance the blade designer’s ability to predict hot spots so coolant may be distributed effectively. The present study uses a novel transient liquid crystal technique to measure heat transfer on a rotating, radially outward coolant channel, which is a simplified model of the actual coolant channels. Various rib types such as 90°, W, and M-shaped ribs of varying types are used to roughen the walls. The present study measures the effects of high rotation numbers (Ro) on the performance and heat transfer distribution of different rib types in developing flow. The present study measures how effective the ribs are up to Ro = 0.5. The Reynolds number (Re) is held constant at 12,000. Results show that in the developing region, the W and M-shaped “high-performance” ribs are just as effective as the simple 90° ribs for increasing heat transfer. The entrance effect in the developing region causes significantly high baseline heat transfer enhancement which may explain why ribs are not as effective as they are in the fully developed region. As the rotation number is increased, results show that the heat transfer on the trailing side increases, while the leading side decreases to a limit and remains constant. For all rotational cases, the W and M-shaped ribs show large changes to the heat transfer distributions on the leading and trailing sides.
Fatigue and Fracture Performance of Insulation System in LNG Carriers
Authors: Kim Myung Hyun , Kim Hyeon Su , Lee Jae Myung , Chun Min Sung , Kim Yang Do , Kang Nam Hyun
Published: August 2012

With the increase of the size of LNG (Liquefied Natural Gas) carriers, LNG cargo containment systems are exposed to more frequent severe sloshing impact actions. In design and construction of LNG carriers, dynamic failure of LNG cargo containment system (CCS) under repeated sloshing impact actions is a very important issue [1]. While the importance of dynamic strength characteristics of LNG cargo containment system is well recognized, no consideration with regard to the fatigue and fracture performance of insulation system toward the cryogenic environment is readily available. In this respect, a systematic experimental research is carried out for the assessment of fatigue and fracture strength of LNG insulation system at both ambient and cryogenic environments. This study begins with the fatigue test of LNG insulation system. In particular, the fatigue characteristic at the secondary barrier is explicitly considered. The effect of the density of R-PUF (Reinforced Poly-Urethane Foam) with respect to fatigue performance is investigated. In the later section, the fracture toughness of LNG Insulation system is characterized in terms of the critical strain energy release rate (GIC) in the context of linear elastic fracture mechanics (LEFM). The specimen geometries used in this study are the center-cracked and double-edge-cracked tension specimen according to ASTM standard [2]. Fracture toughness tests have been carried out for structural components of MARK III type LNG insulation system such as Reinforced Poly-Urethane Foam (Insulation material) and SUS 304L (Primary barrier) under ambient and cryogenic temperature.
Investigation of Low Reynolds Number Experiment and Numerical Simulation on Compressor Cascade
Authors: Hou Anping , Shan Shujun , Wu Yu , Ling Daijun , Jiang Zhengli
Published: August 2012

This paper focuses on the compressor cascade experiment and numerical simulation at order 105 Reynolds number. A cascade tunnel simulated low Reynolds number condition under high subsonic speed. In a series of experiments (Re = 0.9 × 105∼5.0 × 105), oil flow visualization tests were used to indicate boundary layer development of the cascade surface. The results show that the performance of cascades deteriorates rapidly when the Reynolds number decreases to a certain extent. Comparison of results between the tests and calculations demonstrates that the real cascade experimental environment must be considered, such as the effect of the end wall. Flow separation and transition can be predicted accurately by using SST turbulence and Gamma transition models. Through modifying parameters of the Gamma transition model, the profile Mach number distribution in numerical simulations exhibits good agreement with experiments. Response surface methodology was adopted for the design process to minimize the total pressure loss of cascades at the design point. In addition, the optimized result has little negative effect on the high Reynolds number region.
Modeling of Deformations and Stresses During Glass Tempering
Authors: Aronen A. , Karvinen R.
Published: August 2012

Tempered glass must have good strength and visual quality. This is achieved with proper heat transfer control during tempering. Measurement of stresses in tempered glass and temperature measurement during the process are difficult but with simulation the effect of the different process parameters which affect the tempering results and deformations can be studied. A detailed understanding of the process helps to increase the quality of the tempered glass and to decrease the energy consumption of the process. In order to understand the tempering process a theoretical knowledge of heat transfer, mechanics and glass behavior is needed. In the paper the theory of residual stresses is presented and its suitability for use in improvement of the process is discussed.
Theoretical and Experimental Analyses of Energy Efficient Air Dehumidification Systems for Tropical Climates Using Membrane Technology
Authors: Khin Zaw , Ng Kim Choon
Published: August 2012

This paper presents the analytical and experimental analysis of a membrane based air-dehumidification system for handling the latent loads efficiently. This is important for tropical countries like Singapore where the humidity content of ambient air is high and therefore, air conditioning systems need to handle large latent load. A detailed COMSOL simulation model was set-up in order to simulate the water diffusion through the membrane. Experimental results from a real size membrane dehumidification unit are used to validate the mathematical model. Our investigations show that the moisture content of ambient air may be reduced by more than 5 g per kg of air if the dehumidification process is driven by the gradient between the water content of ambient air and the water content of exhaust air form air-conditioned spaces. With the exception of low electricity requirement for air transport, there is no electric energy consumption in the system. Therefore, the membrane system discussed in this paper is an efficient and alternative way of air dehumidification for air conditioning applications, potentially reducing the electricity consumption of air conditioning system in tropics.
Torsional Wave Dispersion in a Pre-Strained Hollow Sandwich Cylinder With Soft Core
Authors: Akbarov S. D. , Kepceler T. , Egilmez M. Mert
Published: August 2012

In this work a torsional wave dispersion in a pre-strained three-layered (sandwich) hollow circular cylinder made from hyper-elastic materials is studied. It is assumed that the material of the core layer is soft than the materials of skin layers and the investigations are carried out within the scope of the piecewise homogeneous body model with the use of the three-dimensional linearized theory of elastic waves in initially stressed bodies. The mechanical relations of the materials of the cylinders are described through their harmonic potential. The analytical expression is obtained for the low wave number limit values of the torsional wave propagation velocity. Moreover, numerical results on the influence of the problem parameters, such as initial strains arising as a result of the stretching or compression of the cylinders along the torsional wave propagation direction, thickness of the layers, mechanical constants of the layers’ materials and etc, are presented and discussed.
Pre-Stressing of Piezoelectric Multilayer Ceramics With Superelastic Shape Memory Alloys
Authors: Bo¨ttcher Jonas , Schiedeck Florian , Mojrzisch Sebastian , Twiefel Jens , Wallaschek Jo¨rg
Published: August 2012

Piezoelectric actuators for dynamic applications must be pre-stressed to avoid tensile stress and to improve their reliability. The actuating behavior of piezoelectric actuators depends strongly on the load characteristics: If the load increases with extension of the piezoelectric ceramic, e.g. when using a classical spring, the actuator cannot reach its nominal displacement; when the load remains constant, e.g. when acting against a mass load, full nominal displacement can be obtained at a maximum operating voltage. A general objective for the design of pre-stressing elements is to realize a small stiffness and sufficient load capacity. For standard materials this requires a good compromise in dimensioning. The nonlinear, hysteretic stress-strain diagram of superelastic shape memory alloys (SMA) is characterized by two stress plateaus during loading and unloading. In this strain range of up to 8%, the stress is nearly constant. Uniaxial tensile loaded spring bars made of superelastic SMA exhibit a theoretical stiffness of 0 N/m in the superelastic range of deformation. Therefore, the constant stress plateaus can provide both, low stiffness and sufficient load capacity. The concept of pre-stressing piezoelectric actuators with superelastic SMA will be analytically designed. In particular, the stress-strain behavior of NiTi-based superelastic SMA will be investigated by measuring major and minor hysteretic loops.
Epi.q Mobile Robots Family
Authors: Quaglia Giuseppe , Bruzzone Luca , Oderio Riccardo , Razzoli Roberto P.
Published: August 2012

The family of Epi.q mobile robots is based on a three-wheeled locomotion unit which is capable of switching between wheeled locomotion and legged locomotion depending on the dynamic conditions, without control intervention. This feature allows to conjugate the benefits of both the locomotion modes: high speed and energetic efficiency on even terrains with the wheeled locomotion, and mobility performance on uneven terrains and in presence of obstacles with the legged locomotion. Two prototypes of the Epi.q family have been already realized and tested, with positive results; a further evolution with four actuated locomotion units (instead of two active and two idle units) is currently under construction. The present paper outlines the evolution of the family of Epi.q mobile robots and proposes several possible architectural evolutions exploiting a modular approach; this approach could be used also to simplify the design phase, obtaining different mobile robots from a limited set of base modules.
Exergy Linked to Environmental Impacts: Advanced Exergoenvironmental Analysis of an Advanced Zero Emission Plant
Authors: Petrakopoulou F. , Tsatsaronis G. , Morosuk T.
Published: August 2012

Exergy-based analyses are useful means for the evaluation and improvement of energy conversion systems. A life cycle assessment (LCA) is coupled with an exergetic analysis in an exergo-environmental analysis. An advanced exergo-environmental analysis quantifies the environmental impacts estimated in the LCA into avoidable/unavoidable parts and into endogenous/exogenous parts, depending on their source. This analysis reveals the potential for improvement of plant components/processes and the component interactions within a system. In this paper, the environmental performance of an advanced zero emission plant (AZEP) with CO2 capture is evaluated based on an advanced exergoenvironmental analysis. The plant uses oxy-fuel technology and incorporates an oxygen-separating mixed conducting membrane (MCM). To evaluate the operation of the system, a similar plant (reference plant) without CO2 capture is used. It has been found that the improvement potential of the AZEP concept is restricted by the relatively low avoidable environmental impact of exergy destruction of several plant components. Moreover, the endogenous environmental impacts are for the majority of the components significant, while the exogenous values are, generally, kept at low levels. Nevertheless, a closer inspection reveals that there are strong interactions among the components of the MCM reactor and the components constituting the CO2 compression unit. Such results are valuable, when the improvement of the environmental performance of the plant is targeted and they can only be obtained through advanced exergy-based methods.
Motion Planning of Uncertain Under-Actuated Dynamical Systems: A Hybrid Dynamics Formulation
Authors: Hays Joe , Sandu Adrian , Sandu Corina , Hong Dennis
Published: August 2012

This work presents a novel nonlinear programming based motion planning framework that treats uncertain under-actuated dynamical systems described by ordinary differential equations. Uncertainty in multibody dynamical systems comes from various sources, such as: system parameters, initial conditions, sensor and actuator noise, and external forcing. Treatment of uncertainty in design is of paramount practical importance because all real-life systems are affected by it, and poor robustness and suboptimal performance result if it’s not accounted for in a given design. System uncertainties are modeled using Generalized Polynomial Chaos and are solved quantitatively using a least-square collocation method. The computational efficiencies of this approach enable the inclusion of uncertainty statistics in the nonlinear programming optimization process. As such, new design questions related to uncertain dynamical systems can now be answered through the new framework. Specifically, this work presents the new framework through a hybrid dynamics formulation for under-actuated systems where actuated state and unactuated input trajectories are prescribed and uncertain unactuated states and actuated inputs are quantified. The benefits of the ability to quantify the resulting uncertainties are illustrated in a power optimal motion planning case-study for an inverting double pendulum problem. The resulting design determines a motion plan that minimizes the required input power—subject to actuator and terminal condition variance constraints—for all possible systems within the probability space.
Simulation and Visualization of Dynamic Systems Using MATLAB, Simulink, Simulink 3D Animation, and SolidWorks
Authors: Tran Loi , Hennessey Michael , Abraham John
Published: August 2012

There are many approaches to simulating and visualizing a dynamic system. Our focus is on developing/understanding and trading-off three different approaches that are relatively easy to implement with inexpensive, commonly available software using combinations of MATLAB, Simulink, Simulink 3D Animation, SolidWorks (basic), SolidWorks (Motion Manager) in addition to several common animation players such as Windows (Live) Movie Maker or the resident animation capability within MATLAB. The “SolidWorks Design Table” approach entails creating MATLAB/Simulink driven time-dependent assembly configurations, associated graphics files (e.g. JPG, TIFF) and then effectively “playing” them sequentially with animation software. The “SolidWorks Motor” approach utilizes SolidWorks’ Motion Manager capability (an add-on), whereby each spatially time-dependent geometric system variable is driven by a “motor” based on MATLAB/Simulink time-dependent data and an animation file can be generated from within Motion Manager. Lastly, in the “Simulink 3D Animation” approach, SolidWorks data is brought into the MATLAB environment and modified with V-Realm Builder (VRML Editor) supplied within the Simulink 3D Animation toolbox to define geometric constraints prior to inclusion as an animation VR Sink block within the Simulink model of the dynamic system. In each case, detailed procedures are provided. To exercise these three different approaches and permit comparisons, a benchmark problem was posed: parallel-parking of a four-wheeled vehicle possessing front wheel steering. Comparisons were then made and the recommended approach depends on such issues as the software background of the developer, the animation quality standard (e.g. framerate), and relative ease of implementation.
Electronic Stool (e-Stool): A Novel Self-Stabilizing Video Capsule Endoscope for Reliable Non-Invasive Colonic Imaging
Authors: Filip Dobromir , Eggermont Marjan , Nagel Jacquelyn , Andrews C. N. , Yadid-Pecht Orly , Mintchev Martin P.
Published: August 2012

Video capsule endoscopy (VCE) has become a popular non-invasive technique to study the small intestine. However, colonic VCE has been problematic due to capsule tumbling in the larger lumen of this organ. Self-stabilizing VCE is a novel method to visualize the colon without tumbling utilizing a biomimetic approach. The proposed design uses the free energy of the body’s natural processes employed to move chyme, and imitates the formation and propagation of stool. In its final stage, it physically and mechanically mimics natural feces. The process starts by administering the capsule orally. The capsule size, shape, and material were chosen to provide a smooth transit throughout the gastrointestinal (GI) tract. Once it reaches the colon, its special outer casing enzymatically dissolves. A stabilizing component that is attached to the back end of the capsule starts quickly expanding in the cecum by osmosis. This increase of the volumetric size of the expandable component (stabilizing component) invokes natural peristalsis by colonic mass reflex. Since the expansion process takes place very quickly, the capsule gets stabilized before the expansion-provoked peristalsis starts. At the final stage, the artificially created expanded component (behaving like an artificial stool) centralizes the capsule during its voyage in the colon, allowing a very smooth transit due to its viscosity. The aim of the present study is to present the design of the capsule from a biomimetic perspective and to comparatively quantify the mechanical properties of the design with those of actual human stool.