bluuebunny/crossref_metadata_2025 huggingface dataset:
A Parametric Study Method of Enhancing the Efficiency of Gas Turbine Combined Cycle Power Plant
Authors: Ji Jingjin , Sun Bo , Zuo Dequan , He Lei
Published: April 2014

At the present time, with the ever-increasing energy price, gas steam combined-cycle power plant is well received and favored by Chinese local investors due to its quickly-start and stop, high operational flexibility, high thermal efficiency, clean exhaust flue gas, short construction period characteristics. Recent researches make many efforts on the optimization of gas turbine intake system, main equipment parameters matching, and cold side of steam turbine to increase the overall performance of combined cycle. In the paper, we focused on a kind of triple-pressure reheat combined cycle equipped with a state of the art gas turbine, which is gradually entering Chinese market. An accurate overall combined cycle model was built up for the purpose of increasing the efficiency by means of steam parameters optimization. The influence of steam pressures and temperatures of each sections, feed-water regenerative heating and fuel preheating on combined cycle performance are evaluated with the model, the restriction factors such as temperature difference of heat recovery steam generator (HRSG) and steam turbine structure design were also considered. A set of optimum parameters are obtained for combined cycle equipped with a state of the art gas turbine by using the proposed method on enhancing combined cycle performance equipped with a certain type of gas turbine.
Optimal Design of Worm Gear System Usage in CVVL for Automobiles
Authors: Park Nogill , Sohn Jonghyeon , Baek Gyeangmyeang , Oh Chunghan
Published: April 2014

Gearing with a ZK worm and an involute helical gear is used in the motor drive system of automotive continuous variable valve lift (CVVL) because of production cost. Since the geared system does not satisfy the meshing condition, transmission error (TE) and teeth interference (TI) are inevitable. This paper introduces a method for reducing TE and eliminating TI. Transmission error function is derived mathematically and used in checking TI. The first prototype for an automobile shows a lot of NVH problem, which is simply combined by coinciding with the helix/lead angles of two gears at the pitch point. By an optimal process with alternating the pressure and helix angles of worm gear system, an prototype of CVVL worm drive of which NVH problem is acceptably solved is designed.
Design Criteria on Sizing and Material Selection of SB-VAWTS
Authors: Ahmadi-Baloutaki Mojtaba , Carriveau Rupp , Ting David S-K.
Published: April 2014

A design methodology has been presented on the sizing and material selection of straight-bladed vertical axis wind turbines. Several design parameters such as turbine power coefficient, blade tip speed ratio, rotor solidity factor, blade aspect ratio and rotor moment of inertia have been analyzed. Material selection and its relevant design criteria have also been discussed for different parts of a straight-bladed vertical axis wind turbines with three blades and two supporting arms per blade. The number of the supporting arms and their optimum locations have been determined via minimizing the bending moments on the blade. A comparative study has also been performed to examine the effect of blade density and turbine H/D ratio on the rotor moment of inertia. It was found that the turbine rotational speed increases as blade density decreases and this increase is larger at higher turbine H/D ratio.
Development of a Non-Invasive Calibration Method for Ocular Tactile Tonometry
Authors: Enikov Eniko T. , Polyvás Péter P.
Published: April 2014

This article describes a novel method of indirect estimation of intra-ocular pressure using tactile sensors. Two sensor calibration methods have been demonstrated: an artificial neural network (ANN) model and a phenomenological reduced-parameter model based on finite element analysis. The ANN method showed superior performance with an accuracy of +/− 0.7 mmHg, while the reduced order method showed an accuracy of +/− 3.11 mmHg. The latter method however allows calibration of the tactile tonometer from a single pressure measurement if the geometry of the probes is known and satisfying certain solvability conditions. The ANN method was demonstrated using experiment data, while the reduced-order model was tested numerically. Due to its indirect and non-invasive nature, the proposed tactile measurement method can be used in the development of a self-administered home tonometer for management of glaucoma, however the presence of an eye lid might require modification of the calibration procedure outlined here.
Environmental Durability of Natural Fiber Reinforced Unsaturated Polyester Composite
Authors: Liao Mengyuan , Ishiaku Umaru Semo , Ishak Zainal Arifin Mohd , Xian Guijun , Hamada Hiroyuki
Published: April 2014

With an industrial increasing interest in sustainable, eco-efficient and green material’s application, natural fiber in polymer composite is guided to develop rapidly, especially kenaf nonwovens in making automotive interior trim parts with its comparative excellent strength and renewability. The objectives of this research are to investigate the environmental degradation behavior on the physical and mechanical properties of kenaf/unsaturated polyester nonwoven composites (KUNC) with special reference to the influence of different geographic natural climate ageing conditions. KUNC was prepared with needle-punched kenaf’s impregnation into unsaturated polyester resin assisted with vacuum oven following by hand lay-up molding. Natural environmental degradation was performed on KUNC by exposing the specimens to Kyoto(Japan), Shanghai(China) and Harbin(China) for a period of 3 months. Weight change and mechanical properties of degraded KUNCs in former three geographic positions in terms of tensile, flexural, impact and fracture toughness were measured instrumentally for ageing effect discussion and comparison. As expected, the aged specimens in those different positions all showed the dropped mechanical properties with weight increasing in varying degrees. Furthermore, the result of degradation level comparison among different positions revealed the positive correlation between increased weight percentages and dropped mechanical properties. In other words, dropped mechanical properties of the degraded composites with increasing weight were attributed to the effect of water, which deteriorates the interfacial properties of composites.
The Investigation of Traditional Japanese Trowel: Part 1 — Process Analysis and Surface Observation
Authors: Sirisuwan Porakoch , Narita Chieko , Koshino Tetsushi , Goto Akihiko
Published: April 2014

The purpose of this study was to study the history of traditional Japanese trowel process. The research study were conducted the trowel blade which was made from SK5 steel. Microstructure and grain sizes were accurately measured by using the optical microscope (OM). The resultant microstructures of hardening were observed as martensite. After the tempering process, the result of microstructure found the temper-martensite structure. In the hardening process was heated up 800–850°C to austenite structure and quenched in cooling oil. Moreover, in the annealing process was quenched into straw ashes for cooling after heat up until 750°C. All heat treatment temperature and surface quality were observed and controlled by eyesight and experience of Japanese expert.
Dynamic Analysis of a Gearless Wind Turbine Coupled to a DFIG
Authors: Ericson Grant A. , Srivastava Nilabh
Published: April 2014

Most modern wind turbines use power electronic converters to maintain voltage phase, frequency, and magnitude at the grid-dictated values. However, such converters have often been reported to have high failure rates and cost. Further, failure of conventional wind turbine gearboxes adds to the overall cost and downtime. One remedy to limit the size of these converters is to implement a continuously variable transmission (CVT) which has fewer moving parts, e.g. a belt/chain CVT. Further, a CVT may completely eliminate the conventional gearbox architecture used in current wind turbine drivetrains. However, several dynamical issues related to CVTs prevent their widespread use. Current dynamical understanding of the most common CVTs (i.e. a belt/chain CVT) is limited by formulations of shift speed, belt-pulley friction torques, as well as belt-pulley slip. This paper aims to redress the shift speed formulation which has been widely based on quasi-static equilibrium analyses and, surprisingly, on slip definitions that provide minimal detail on the inertial interactions between the belt and the pulleys. Consequently, the paper proposes a new definition of slip to capture such interactions and uses it to develop more accurate representations of belt-pulley friction torques. Using MATLAB/Simulink, the CVT model is incorporated into a wind turbine model with a doubly-fed induction generator (DFIG). Further, the entire turbine/rotor-CVT-generator model is coupled to the grid through the conventional grid- and rotor-side converters (i.e. GSC and RSC respectively). The results for the overall integrated powertrain are presented and discussed in detail with the CVT operated in open-loop and the DFIG in closed-loop. The intent is to study how control inputs of a CVT affect power flow through the entire drivetrain to meet the objectives of a) maximal power extraction from the wind and b) tracking the grid demands without degrading the CVT performance (with regard to slip, torque capacity, etc.). Further, the results presented herein examine the ability of a CVT to provide speed control (which traditionally is achieved via RSC), thereby, offering the potential to downsize RSC and thus the overall converter.
The Evaluations of the Muscle Activity During “Momi” by Using the Different Immersed Bamboo in Water to Making Kyo-Uchiwa (Japanese Paper Fan)
Authors: Sirisuwan Porakoch , Narita Chieko , Koshino Tetsushi , Yuminaga Hisanori
Published: April 2014

The aim of study is to evaluate whether altering the bamboo moisture by immersed bamboo in water on 4-hour and 3 -day that would affect the muscle activity during separated bamboo by bending process. Moreover, thirteen muscles which bilateral side of Pectoralis major, Biceps brachii, Triceps brachii, Latissimus dorsi, Gluteus medius and only right side of Rectus abdominis, Extensor carpi radialis longus and Flexor carpi radialis were recorded. As a result, the bilateral side of Biceps brachii, right side of Extensor carpi radialis longus and Flexor carpi radialis, left side of Triceps brachii showed the difference quite clearly. When the craftsman was bending the bamboo he was necessary more effortful by these muscles activity on the 4-hour immersed bamboo in water than the 3-day. The scanning electron microscopy (SEM) photographs showed the fracture characteristic of 2 subjects that the adhesive of bamboo fiber decreased when increased moisture.
Stochastic Sensitivity Analysis of Structural Systems With Interval Uncertainties
Authors: Muscolino Giuseppe , Santoro Roberta , Sofi Alba
Published: April 2014

Interval sensitivity analysis of linear discretized structures with uncertain-but-bounded parameters subjected to stationary multi-correlated Gaussian stochastic processes is addressed. The proposed procedure relies on the use of the so-called Interval Rational Series Expansion (IRSE), recently proposed by the authors as an alternative explicit expression of the Neumann series expansion for the inverse of a matrix with a small rank-r modification and properly extended to handle also interval matrices. The IRSE allows to derive approximate explicit expressions of the interval sensitivities of the mean-value vector and Power Spectral Density (PSD) function matrix of the interval stationary stochastic response. The effectiveness of the proposed method is demonstrated through numerical results pertaining to a seismically excited three-storey frame structure with interval Young’s moduli of some columns.
Multi-Scale Spatial-Temporal Modelling of 18F-FLT Dynamics and its Relation to 3-Compartment Model
Authors: Liu Dan , Chalkidou Anastasia , Marsden Paul K. , Fenwick John D.
Published: April 2014

3′-Deoxy-3′-18F-fluorothymidine (18F-FLT) is a radiotracer which accumulates in proliferating cells and is used for positron emission tomography (PET) imaging. This study investigates the heterogeneous transport and uptake of FLT in tumors, aiming to understand the links between FLT dynamics described by a mechanistic spatial-temporal model and by a simplified 3-compartment model, and to study the validity of the compartment model.

In the proposed multi-scale spatial-temporal model, the tumor consists of vasculature, interstitium and tumor cells. The heterogeneous spatial-temporal distribution of FLT is determined by a convection-diffusion-reaction equation, numerically solved using the finite difference method (FDM). Physiological parameters were collated from the literature and used as model coefficients, and vascular maps were created based on histological micro-vascular density (MVD). Results show that the multi-scale model can generate FLT time activity curves (TACs) similar to TACs derived from clinical PET images. And so long as the region of interest (ROI) is a near-closed system, a 3-compartment model can recover reasonable estimates of averaged FLT dynamics.
Behavior and Performance of Refrigerant Mixture HFC125/HC290 in Heat Pumps
Authors: Fan Xiaowei , Wang Fang , Zheng Huifan , Zhang Xianping , Xu Di
Published: April 2014

The refrigerant mixtures provide an important direction in selecting new environment-friendly alternative to match the desirable properties with the existing halogenated refrigerants or future use in the new devices, in which, HFCs refrigerants with zero ODP combined with HCs refrigerants with zero ODP and lower GWP are of important value in the fields of application. In the present work, research on HFC125/HC290 (25/75 by mass) binary refrigerant mixture used in heat pumps was carried out, and parameters, factors affecting the performance were investigated, and compared with that of HCFC22 under the same operating conditions. It has been found that the new mixture can improve the actual COP by 2 to 13% and hence it can reduce the energy consumption by 20 to 31.5%. The overall performance has proved that the new refrigerant mixture could be a promising substitute for HCFC22.
Dynamic Modeling, Simulation and Exergy Analysis of an Innovative Hydronic Heating System
Authors: Sangi R. , Streblow R. , Müller Dirk
Published: April 2014

In this study, dynamic modeling and simulation of a decentralized hydronic heating system has been performed. The simulated space heating system is a model of an innovative heating system of an apartment with a boiler that supplies heat for eight radiators which are served by distribution pipes. Eight small pumps, located at the outlet of the radiators instead of a central circulation pump, work according to demand, and supply each radiator with hot water only when required. A PID controller regulates the rotational speed of the pumps and consequently the power of the radiators to maintain the room temperature at the set point.

To evaluate the performance of such a heating system, a model of the entire energy chain from generation to distribution is needed. Therefore, in this work, detailed sub-models for the hydraulic system have been developed and coupled with the model of a building to make a general model for simulating the performance of the whole system. The analysis has been carried out by simulation of the system using the object-oriented programing language Modelica. Dymola, which is a multi-domain modeling and simulation tool, has been used as simulation environment. The Modelica Standard Library 3.2 and the Modelica libraries for building simulation such as BaseLib, Database, Building and HVAC components libraries have been applied to simulate the hydraulic and thermal behavior of the system. In the next step, the system has been analyzed form exergy point of view and the simulation results from the dynamic model have been presented in an exergetic framework.
Development of a Fluids Laboratory Experience in Dimensional Analysis and Similitude Applied to Vortex Shedding From a Cylinder in Cross-Flow
Authors: Anderson Matthew , Shiltz Dylan , Damm Christopher
Published: April 2014

A fluids laboratory experience that introduces students to dimensional analysis and similitude was designed and performed in a junior-level first course in fluid mechanics. After students are given an introduction to dimensional analysis, the technique is applied to the phenomenon of vortex shedding from a cylinder in cross-flow. With help from the instructor, lab groups use dimensional analysis to ascertain the relevant dimensionless pi terms associated with the phenomenon. After successfully determining that the pi terms are the Strouhal number and the Reynolds number, experiments are performed to elucidate the general functional relationship between the dimensionless groups. To conduct the experiments, a wind-tunnel apparatus is used in conjunction with a Pitot tube for measurements of free stream velocity and a platinum-plated tungsten hot-wire anemometer for rapid (up to 400 kHz) measurements of velocity fluctuations downstream of the cylinder. Utilizing an oscilloscope in parallel with a high-speed data acquisition system, students are able to determine the vortex shedding frequency by performing a spectral analysis (via Fourier transform) of the downstream velocity measurements at multiple free stream velocities and for multiple cylinder diameters (thus a varying Reynolds number). The students’ experimental results were found to agree with relationships found in the technical literature, showing a constant Strouhal number of approximately 0.2 over a wide range of Reynolds numbers. This exercise not only gives students valuable experience in dimensional analysis and design of experiments, it also provides exposure to modern data acquisition and analysis methods.
Conjugate Heat Transfer CFD Predictions of the Surface Averaged Impingement Heat Transfer Coefficients for Impingement Cooling With Backside Cross-Flow
Authors: El-Jummah Abubakar M. , Abdul Hussain Reyad A. A. , Andrews Gordon E. , Staggs John E. J.
Published: April 2014

A 10 row impingement heat transfer configuration with a single sided exit at the end of the impingement gap was modelled using conjugate heat transfer CFD. The predictions were compared with experimental results for an electrically heated, 6.35mm thick, metal wall of nimonic-75, which was impingement cooled. The geometry investigated was a square array of inline impingement 10 × 10 holes with X/D of 4.66 and Z/D of 3.06, where D = 3.27mm. The use of metal walls enabled the local surface averaged heat transfer coefficient h, to be estimated from an imbedded thermocouple that logged the rate of cooling when the heating was removed. Conjugate heat transfer analysis provided local h values, which were surface averaged for comparison with the measured h. The CFD results also provided velocity, turbulence and Nusselt number distributions on the target and impingement jet surfaces. The aerodynamics data enabled the pressure loss of the system to be predicted, which compared well with experimental measurements. The predicted surface distributions of Nusselt number were similar to the surface turbulence kinetic energy distributions, which demonstrated the importance of turbulence in convective heat transfer. Surface averaged heat transfer coefficients were predicted and are in good agreement with the measurements for five coolant mass flow rates. The predicted and measured results for surface averaged h were similar to measurements of other investigators for similar impingement geometries.
Fatigue Life Prediction and Optimal Design of a Flexure Based Micro-Motion Stage
Authors: Wang Qiliang , Zhang Xianmin
Published: April 2014

This paper presents a fatigue-based method for optimal design of a flexure based 3-RRR compliant micro-motion stage, which is driven by three piezoelectric actuators (PZT). As this compliant stage obtains motions from the deflection of its flexure hinges, fatigue failure becomes its major failure mode. The aim of this paper is to provide a method to predict the fatigue life of the stage and redesign it by considering fatigue strength. Firstly, the motion transformation matrix, which reveals the relation between output displacement vector of moving platform and three input displacements of PZT actuators, is established by using the finite element method. Then, the force vectors of all the twelve flexure elements in the stage can be derived. Secondly, the fatigue properties of circular flexure hinge are discussed by considering the effects of flexure dimension parameters, non-zero mean stress, surface conditions and et al. Combined with the material stress life curve and the fatigue strength of the flexure hinges, fatigue life prediction of the micro-motion stage can be carried out by utilizing the nominal stress approach. The aforementioned micro-motion stage, which is optimized based on maximum stress constraint, is presented as an example to illustrate the fatigue life prediction procedure. And the predicted results of fatigue lives in specified condition indicate that fatigue lives of all flexure hinges in the stage differ drastically. In this condition, the stage will fail prematurely due to the most vulnerable hinge. So, the design method based on static strength may lead to unsafe or uneconomic design of the stage. Finally, a fatigue based optimal design method is introduced to redesign the flexure based micro-motion stage. The stage dimensions and the flexure hinge geometry are considered as design variables. The maximum motion range is set as the objective function. And the fatigue strength of flexures is taken as constraint, as well as the natural frequency of the stage and the input force capacity of PZT actuators. A micro-motion stage with optimal dimension parameters is obtained at last. Numerical results show that the optimal stage has a good comprehensive properties and can endure a infinite cycles.
Engineering Decision Making in an Open Age
Authors: Fukuda Shuichi
Published: April 2014

In an age of diversification and changes, a new framework for decision making for a team is required. As growing complexity and diversification call for team members from a wide variety of areas, a decision cannot be made one-time as it used to be and it must be reached by trials and errors step by step. Such dynamic decision making has to convince members at each step by providing different perspectives for each member to understand the line of reasoning, and must allow lazy evaluation, because some members cannot understand what pieces of knowledge and experience are called for until later step, when clearer perspective is available. Steps proceed by satisfying at least one member. If it fails, then it backtracks to the previous step until it satisfies one more member. This process is repeated until all members are satisfied.

Artificial Intelligence allows such trial and error decision making to make all members feel satisfied. The usefulness of this approach is demonstrated by applying developed WPS producing tool to many applications in industry.

And it is believed this DDM tool will be very useful for decision making in other areas, too, where systems are very complex and diverse.
Nonlinear Dynamics of an Electrically Actuated MEMS Device: Experimental and Theoretical Investigation
Authors: Ruzziconi Laura , Ramini Abdallah H. , Younis Mohammad I. , Lenci Stefano
Published: April 2014

This study deals with an experimental and theoretical investigation of an electrically actuated micro-electro-mechanical system (MEMS). The experimental nonlinear dynamics are explored via frequency sweeps in a neighborhood of the first symmetric natural frequency, at increasing values of electrodynamic excitation. Both the non-resonant branch, the resonant one, the jump between them, and the presence of a range of inevitable escape (dynamic pull-in) are observed. To simulate the experimental behavior, a single degree-of-freedom spring mass model is derived, which is based on the information coming from the experimentation. Despite the apparent simplicity, the model is able to catch all the most relevant aspects of the device response. This occurs not only at low values of electrodynamic excitation, but also at higher ones. Nevertheless, the theoretical predictions are not completely fulfilled in some aspects. In particular, the range of existence of each attractor is smaller in practice than in the simulations. This is because, under realistic conditions, disturbances are inevitably encountered (e.g. discontinuous steps when performing the sweeping, approximations in the modeling, etc.) and give uncertainties to the operating initial conditions. A reliable prediction of the actual (and not only theoretical) response is essential in applications. To take disturbances into account, we develop a dynamical integrity analysis. Integrity profiles and integrity charts are performed. They are able to detect the parameter range where each branch can be reliably observed in practice and where, instead, becomes vulnerable. Moreover, depending on the magnitude of the expected disturbances, the integrity charts can serve as a design guideline, in order to effectively operate the device in safe condition, according to the desired outcome.
Application of Sliding Segment and Rolling Segments Drag Factors in Roll Phase Speed and Roll Rate Calculations
Authors: Arndt Mark William
Published: April 2014

During the roll phase of a rollover crash and beginning at the point of trip, three segments have been distinguished. The segments are (1) the first airborne distance and (2, 3) distances associated with two segments in a bi-constant deceleration response. The bi-constant deceleration response was discovered in over-the-ground speed analysis of rollover crash video complemented by analysis of recorded instruments and detailed post-rollover documentation. The bi-constant deceleration response has been theorized as attributable in the first region to a sliding mechanism and transitioning in the second region to a rolling mechanism. Experimentally reported results are used in a probabilistic simulation to predict speed, roll rate and extent (time and angle). Results allow for predicting speed and roll rate in the time and displacement domain dictated by analyst’s constraints and preferred statistical cutoffs. Description of the model is followed by examples of its application in actual rollovers and comparison to experiment results.
Mechanical Design and Students’ Creativity: “Think Outside the Box”
Authors: Mokhtar Wael
Published: April 2014

A design project was used in junior level mechanical design course to challenge the students’ creativity skills. Beside the theoretical foundation of the course subject, the students were introduced to several professional skills such as: decision making tools, technical review meetings, interaction with customers, and teamwork skills. The design challenge was to develop a bike rack to meet a list of technical and marketing constraints. Details of the project requirements are presented with a brief overview of the main project mentoring tools. Students’ creativity is discussed through two samples of the student work.

It was noticed that, the basic creativity skills of the students can be improved by using some of the training tools, however, the students vary in their response to this training.
Investigation of Methanol Based Air-Air Thermosyphon Heat Exchangers
Authors: Ravi Bharath Viswanath , Michael Mukilan Sebastiraj , Krishna S. Audithya , Arunachalam Lakshmanan , Mariappan Suresh
Published: April 2014

Thermosyphons are self-actuated heat transport systems in which the circulation of the working fluid is brought about by a combination of gravity and buoyant forces. In the recent years, thermosyphons have been considered for widely diverse heat recovery applications, especially in HVAC systems. In this work, a systematic approach for design and analysis of finned air-air thermosyphon heat exchanger system based on effectiveness-NTU method is presented. Furthermore, the effect of mass flow ratio of the hot and cold air stream, temperature difference between the hot and cold air streams, transverse tube spacing, fin spacing and length of the thermosyphon on the effectiveness of the system is predicted by numerical simulation. In addition, the thermal performance of unfinned thermosyphon heat exchanger system has also been investigated experimentally.
Understanding the Effect of Baseline Modeling Implementation Choices on Analysis of Demand Response Performance
Authors: Addy Nathan , Mathieu Johanna L. , Kiliccote Sila , Callaway Duncan S.
Published: April 2014

Accurate evaluation of the performance of buildings participating in Demand Response (DR) programs is critical to the adoption and improvement of these programs. Typically, we calculate load sheds during DR events by comparing observed electric load against counterfactual predictions made using statistical baseline models. Many baseline models exist and these models can produce different shed estimates. Moreover, modelers implementing the same baseline model can make different modeling implementation choices, which may affect shed estimates. In this work, using real data, we analyze the effect of different modeling implementation choices on shed estimates. We focus on five issues: weather data source, resolution of data, methods for determining when buildings are occupied, methods for aligning building data with temperature data, and methods for power outage filtering. Results indicate sensitivity to the weather data source and data filtration methods as well as an immediate potential for automation of methods to choose building occupied modes.
Numerical and Experimental Measurements of Die Swell for a LCP and an Amorphous Polymer
Authors: Ahmadzadegan Arash , Saigal Anil , Zimmerman Michael A.
Published: April 2014

It is known that liquid crystalline polymer (LCP) melts have a high elasticity which can be measured from its effect on the rheology on the cessation of shear. On the other hand, LCPs show very limited die swell after extrusion. In this paper, the results of experimental measurements of the die swell for a liquid crystalline material and polypropylene (PP), an amorphous polymer, are presented. The extrudate thickness 5 cm below the die lip is optically measured and the results are analyzed using ImageJ software. A numerical simulation of the die swell based on the capillary rheometry data and oscillatory rheometry is performed for LCP materials using ANSYS ® POLYFLOW ®. Different viscoelastic properties are used to model the LCP and optimum properties to model the die swell for the base volume flow rate are determined. Results show similarity between die swell modeling for the LCP at the base volume flow rate but increasing the die swell results in some deviation from the experimental results.
Effects of Aircraft Aeroelastic Deformations on External Store Separation Dynamics
Authors: Kozak Mustafa Tugrul , Yildiz Erdinc Nuri , Yazicioglu Yigit , Cigeroglu Ender
Published: April 2014

Store separation analyses are carried out in order to estimate the safe separation envelope for external stores carried on military aircrafts by varying the flight/ejection conditions. Typical separation analysis considers either only the store motion beyond the end-of-stroke (EoS), or solves the EoS conditions with predefined ejection forcing that are assumed to be unaltered with respect to flight/ejection conditions. There exists a gap in the literature in modeling the EoS conditions and precise ejection loads. Data from ground and flight tests show that, dynamic responses of a store differ beyond acceptable limits where aerodynamics and aircraft elasticity are the two main sources of this miscorrelation. In order to have a reliable mathematical model that modifies the ground test data to have a reasonable correlation with the real ejection case, not only ejector and store dynamics but also store aerodynamics, aircraft aerodynamics, aircraft rigid body dynamics, aircraft elasticity should be considered. To show the effects of aircraft deformation on the EoS store conditions, first of all, a methodology that can be used to estimate the ejection loads and EoS conditions of the store more precisely is presented. For the purpose of visualizing the aeroelastic effects on store ejection dynamics, various virtual test cases are handled by changing wing torsional stiffness values and store mounting station positions along aircraft longitudinal axis. The acceleration responses of the store, obtained with and without the inclusion of aeroelastic effects, are used to emphasize the effects of aeroelasticity on ejection.
An Experimental Investigation of a Temperature Controlled Vapor Supply System
Authors: Ryan Robert G. , Bunting Jeffrey
Published: April 2014

A variety of applications require a constant pressure vapor supply for processes such as purging fluid systems. A typical design would use a high pressure tank of gas (e.g. helium) along with a mechanical pressure regulator to deliver a constant pressure flow. An alternative concept for the vapor source is to use a tank containing a saturated liquid-vapor mixture. As the vapor is drawn off of the top of the tank, the temperature of the mixture is controlled to maintain the desired vapor delivery pressure. The potential advantage of this approach is that the vapor supply system can be designed to be lighter, more compact, and safer.

An experiment was designed to test the practicality of this concept in a small scale system. Carbon dioxide was chosen for the saturated mixture due to its availability, safety, and desirable operating pressures near ambient temperature levels. The apparatus was designed to allow for the measurement of relevant temperatures and pressures over a range of vapor delivery flow rates. Temperature control of the supply tank was accomplished by submergence in an ice bath. The experimental results confirm that this type of system can produce a well regulated vapor supply at low flow rates, but fails to produce steady pressures at higher delivery flows due to limitations of the heat transfer process in the supply tank.
Analysis of the Possibility of Water Induction in Turbine From Direct Contact Water Heater at Load Shedding Power
Authors: Gotovsky M. A. , Ermolov V. F. , Mikhailov V. E. , Sukhorukov Yu. G. , Trifonov N. N.
Published: April 2014

Direct-contact heaters of feed water are especially popular as low-pressure heaters (LPH). These devices are successfully used in Russia during a long time both for conventional and nuclear power plants. Moreover, abilities of such devices to operate as deaerators led to the development deaeratorless schemes. One of most important conditions of reliable operating of such LPH is the prevention of damage of steam turbines, because of back flow of wet steam to the turbine. In this paper processes of boiling up are considered in direct contact LPH-2 which occur during stopping of turbine and its specific features concerned with dependence of sonic speed two-phase flow on vapor and liquid volumetric portions during flow enter in compensating tubes. Computer analysis showed, that the rate of generation of steam in the superheated water depends on the pressure exceptionally strong.

Zone of churn flow regime, which is formed in the upper part of the condensate tank appears very sensitive instrument of flow rate control. As it is shown in such a situation, the system becomes self-governing and will not miss a steam consumption, which leads to the entrance some part of churn regime zone to pressure equalizing tubes. The calculations show that the safety can be ensure even in the conditions when backpressure valve absent. Such the conclusion is confirmed by the experience on operation direct contact LPH in Russian power plants.
Effective Temperature Jump Length and Influence of Axial Conduction for Thermal Transport Through Channels With Superhydrophobic Walls
Authors: Cowley A. , Maynes D. , Crockett J. , Webb B. W.
Published: April 2014

This paper presents a numerical investigation of thermal transport in a parallel-plate channel comprised of superhydrophobic walls. The scenario analyzed in this paper is laminar, fully developed, steady flow with constant properties. The superhydrophobic walls considered here have alternating micro-ribs and cavities aligned perpendicular to the flow direction. The cavities are assumed to be non-wetting and contain air. The thermal transport through the ribs is considered to have a constant heat flux while the thermal transport through the air/fluid interface over the cavity is considered to be negligible. Numerical results have been obtained over a range a Peclet numbers, cavity fractions, and relative rib/cavity widths. Results were also obtained where axial conduction was neglected and these results are compared to previous analytical work with excellent agreement. When the influence of axial conduction is not neglected, however, the results for local wall temperatures and Nusselt numbers show departure from the previous analytical results. The departure is more pronounced at low Peclet numbers and at large relative channel diameters. This paper provides a comparison over a wide range of parameters that characterize the overall influence of axial conduction. In general, the results show that the relative size of the cavity compared to the total rib/cavity module width (cavity fraction) and the flow Peclet number have a significant impact on the total thermal transport properties. Also, the rib/cavity module width compared to the hydraulic diameter affects the overall thermal transport behavior. Lastly, this paper explores the concept of a temperature jump length which is analogous to the hydrodynamic slip length. The ratio of temperature jump length to hydrodynamic slip length is presented in terms of cavity fraction, Peclet number, and relative size of the rib cavity module.
A New Particle Swarm Optimization and Differential Evolution Technique for Constrained Optimization Problems
Authors: Al-Ani Dhafar , Habibi Saeid
Published: April 2014

Real-world problems are often complex and may need to deal with constrained optimization problems (COPs). This has led to a growing interest in optimization techniques that involve more than one objective function to be simultaneously optimized. Accordingly, at the end of the multi-objective optimization process, there will be more than one solution to be considered. This enables a trade-off of high-quality solutions and provides options to the decision-maker to choose a solution based on qualitative preferences. Particle Swarm Optimization (PSO) algorithms are increasingly being used to solve NP-hard and constrained optimization problems that involve multi-objective mathematical representations by finding accurate and robust solutions. PSOs are currently used in many real-world applications, including (but not limited to) medical diagnosis, image processing, speech recognition, chemical reactor, weather forecasting, system identification, reactive power control, stock exchange market, and economic power generation. In this paper, a new version of Multi-objective PSO and Differential Evolution (MOPSO-DE) is proposed to solve constrained optimization problems (COPs). As presented in this paper, the proposed MOPSO-DE scheme incorporates a new leader(s) updating mechanism that is invoked when the system is under the risk of converging to premature solutions, parallel islands mechanism, adaptive mutation, and then integrated to the DE in order to update the particles’ best position in the search-space. A series of experiments are conducted using 12 well-known benchmark test problems collected from the 2006 IEEE Congress on Evolutionary Computation (CEC2006) to verify the feasibility, performance, and effectiveness of the proposed MOPSO-DE algorithm. The simulation results show the proposed MOPSO-DE is highly competitive and is able to obtain the optimal solutions for the all test problems.
Generation of Pressure Distribution Inside a Decay Tank in a Research Reactor Using CFD
Authors: Kim Seong Hoon , Seo Kyoungwoo , Chi Dae-young , Yoon Juhyeon
Published: April 2014

The Primary Cooling System (PCS) of a research reactor circulates coolant to remove the heat produced in the fuel or irradiation device. The core outlet coolant contains many kinds of radionuclides because it passes the reactor core [1]. As N-16 among them emits a very hard gamma ray, it not only causes radiation damage to some components but also requires very heavy shielding of the primary cooling loop. Since its half-life is 7.13s, its level can be effectively lowered by installing a decay tank including an internal structure to provide a transit time [2]. To ensure that the N-16 activity decreases enough before the coolant leaves the heavily shielded decay tank room, perforated plates are installed inside the decay tank. The perforated plates are designed to disturb and delay the PCS flow. Normally, when a flow from a relative narrow inlet nozzle goes out to an enlarged tank, it becomes a complex turbulent flow inside the tank. In addition, the PCS flow is frequently changed from zero to a normal flow rate owing to the research reactor characteristics. Thus, the integrity of the perforated plate shall be verified with the pump operation and shutdown condition.
Steady State Parametric Modeling of Non-Conventional Loop Heat Pipes
Authors: Remella Karthik S. , Gerner Frank M. , Shuja Ahmed
Published: April 2014

Loop Heat Pipes (LHPs) are used in many thermal management applications, especially for micro-electronics cooling, because of their ability to passively transport thermal energy from a source to a sink. This paper describes the development of a parametric model for a non-conventional LHP operating in steady state, employed to cool Light Emitting Diodes (LEDs). This device is comprised of a flat evaporator, and a finned circular loop wherein condensation and sub-cooling of the working fluid takes place. Unlike a conventional LHP, this device has no compensation chamber. In the mesh screen of the evaporator, the vapor flow entrains liquid and hence the quality of the two-phase mixture leaving the evaporator (xevap) is less than unity (unlike in a conventional LHP where saturated vapor leaves the evaporator). Since this lower quality (approximately 0.2) results in a smaller ratio of latent energy to sensible energy being removed by the condenser and sub-cooler respectively; the ratio of the length of the sub-cooler to condenser length is significantly larger. This results in more stable and controlled operation of the device. Mathematical models of the evaporator, the condenser and the sub-cooler sections are developed, and two closure conditions are employed in this model. For consistency and accuracy, some parameters in the model, such as the natural convection heat transfer coefficient (h o) and a few thermal resistances in the evaporator, are estimated empirically from test data on the device. The empirically obtained value of the heat transfer coefficient is in very good agreement with correlations from the literature. The parametric model accurately predicts the LED board temperature and other temperatures for a specific amount of thermal energy dissipated by the LEDs.
Manufacturing Additively, With Fresh Concrete
Authors: Di Carlo Tony , Khoshnevis Behrokh , Chen Yong
Published: April 2014

This research explores mega-scale additive manufacturing, using fresh concrete. In traditional concreting, rigid forms mold and protect young concrete, like an exoskeleton. Typically, these forms are not removed until the maturing material has developed considerable load-bearing strength. Conversely, Contour Crafting, an automated construction technology under development at the University of Southern California, proposes to rapidly fabricate civil structures additively — layering continuous ribbons of fresh unconfined concrete. The process, which is akin to 3-D printing, leverages a special polymer-modified concrete which is both highly workable and shape–stable. However, without exoskeleton, the freshly layered concrete must be load-bearing immediately upon placement. This is an unprecedented structural requirement, and little has been done to substantiate uncured concrete as a load-bearing member. This research establishes the build rates and material health monitoring necessary to erect these structures safely, and demonstrates the Contour Crafting process is viable.
Performance Study of Anaerobic Digestion of Organic Municipal Waste in Upflow Bioreactor With Central Substrate Dispenser
Authors: Nwaigwe Kevin N. , Ogueke Nnamdi V. , Ononogbo Chibuike , Anyanwu Emmanuel E.
Published: April 2014

A performance study of anaerobic digestion of organic municipal waste in upflow bioreactor with central substrate dispenser is presented. The experimental rig is based on an integrated system of bioreactors consisting of Upflow Bioreactor (UB), Upflow Bioreactor with Central Subtrate Dispenser (UBCSD), and Continous Stirred Tank Reactor (CSTR) each having internal volume of 76 litres, 64.8 litres, and 76 litres respectively. The scheme is used for minimizing the mixing and fouling problems associated with some conventional bioreactors during digestion reaction. Organic municipal waste (OMW) was used to prepare the slurry for the reactors. Microbial reaction was enhanced during operation using a measured quantity (2kg) of substances from the rumen of a newly slaughtered cow. The experimentation from feeder tank to Bioreactors was carried out for a period of 10-days Hydraulic Retention Time (HRT) at 37°C. Effects of some basic parameters affecting anaerobic digestion in terms of biogas production and Chemical Oxygen Demand (COD) reduction were carried out. They include substrate temperature, minimal average temperature, changes in temperature, substrate content and properties, available nutrient, retention time, organic loading rate, pH level, nitrogen inhibition and C/N ratio, substrate agitation, and inhibitory factors. Results showed that UBSCD generated the highest level of Biogas yield of up to 52915 ml, while UB and CSTR yielded 23550ml and 28980ml respectively. Similarly for COD removal, 24343 mg/l, 5775.4 mg/l, and 23155 mg/l were achieved for UBCSD, UB and CSTR respectively from an initial value of 120,320 mg/l. These results show that the use of UBCSD better enhances biofuel production from organic municipal waste.
Nonlinear Control of a Magnetic Levitation System Using Single Multiplicative Neuron Models
Authors: Hall Daniel L. , Samanta Biswanath
Published: April 2014

The paper presents an approach to nonlinear control of a magnetic levitation system using artificial neural networks (ANN). A novel form of ANN, namely, single multiplicative neuron (SMN) model is proposed in place of more traditional multi-layer perceptron (MLP). SMN derives its inspiration from the single neuron computation model in neuroscience. SMN model is trained off-line, to estimate the network weights and biases, using a population based stochastic optimization technique, namely, particle swarm optimization (PSO). Both off-line training and on-line learning of SMN have been considered. The ANN based techniques have been compared with a feedback linearization approach. The development of the control algorithms is illustrated through the hardware-in-the-loop (HIL) implementation of magnetic levitation in LabVIEW environment. The controllers based on ANN performed quite well and better than the one based on feedback linearization. However, the SMN structure was much simpler than the MLP for similar performance. The simple structure and faster computation of SMN have the potential to make it a preferred candidate for implementation of real-life complex magnetic levitation systems.