bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Development of a Low Cost Pyrheliometer
Authors: Gnos Michael , Greska Brenton , Krothapalli Anjaneyulu
Published: January 2011

A low cost pyrheliometer, based on a thermoelectric sensor, was developed at the Energy and Sustainability Center at the Florida State University. In addition, an inexpensive double-axis tracking device, capable of autonomous operation, enables the pyrheliometer to operate as a stand-alone system. Widely available off-the-shelf components were used and compromises in accuracy and time responsiveness were made in order to keep the cost low. The obtained data was compared with an Eppley Normal Incidence Pyrheliometer (NIP) using model ST-1 solar tracker. Steady state values of irradiance were measured with an accuracy better than ±2%. Transient measurements are time delayed by a thermal lag of about two minutes, which leads to a high error for instantaneous measured values. However, the integrated irradiance over the course of any given day yields irradiation values with accuracy better than ±2%, even on days when the sun and clouds quickly alternate. Based on a manufacturing cost analysis, the prototype pyrheliometer is anticipated to cost less than $500 if mass-produced.
Policy Solutions for Increasing Economic Impacts of Wind Development in Arizona
Authors: Wadsack Karin E. , Acker Tom
Published: January 2011

Arizona recently dedicated its first utility-scale wind plant, the 63-MW Dry Lake Wind Project on private, state and BLM land near Holbrook. While Arizona has developable wind resources and some available transmission capacity, wind power development has not taken off in the state, and this is often attributed to policy issues and resource quality. The National Renewable Energy Laboratory’s Western Wind & Solar Integration Study quantified the wind capacity that should be built in Arizona under various wind development scenarios, including all-in-state development, least-cost wind resource across the western electric grid in the inter-mountain west, and a scenario providing some accounting for local economic impacts of wind development. In scenarios in which up to 20% of Arizona’s electrical energy was served by wind resources developed within Arizona, the study found that instate wind development actually resulted in a lower overall system operating cost of energy to state consumers than any other scenario (despite higher capacity factor sites being available outside of Arizona). In addition, the economic impacts of this potential development offer revitalization to many of the rural areas in the state. However, the state lacks coherent policies to attract wind power development and to bolster the services available in rural areas to meet the needs of developers during construction and operation of wind power plants. This study presents and evaluates policy mechanisms for use by the state, county, or tribal governments to increase wind penetration, attract wind development through financial incentives, and increase the local economic impacts of the development once it takes place. Example policies from other states, counties, and tribal governments are evaluated with regard to their appropriateness in Arizona, and suggestions are made for changes to federal policy that would increase the viability and impact of wind development projects on tribal land nationwide.
Correlations Between Geographically Dispersed Concentrating Solar Power and Demand in the United States
Authors: Mowers Matthew , Helm Chris , Blair Nate , Short Walter
Published: January 2011

Correlations between the electricity generated by concentrating solar thermal power (CSP) plants, as well as cross-correlations between CSP, wind power and electricity demand, have significant impacts on decisions for how much and where to build utility-scale CSP capacity, the optimal amount of thermal storage in the CSP plants, reserve capacity needed to back-up the system, as well as the expected levels of curtailed renewable power. Accurately estimating these correlations is vital to performing detailed analyses of high renewable penetration scenarios. This study quantifies the degree of correlation between geographically dispersed CSP, as well as the correlation between CSP and wind power, and CSP and electricity demand in 356 discrete regions in the contiguous US. Correlations are calculated using hourly data on an annual basis. Maps of the correlations will be presented to illustrate the degree of correlation between solar power and the demand it is serving, as well as the synergies between the negatively-correlated wind power and solar power serving the same region.
Application and Development of Renewable Energy: A Case Study of Solar Energy Utilization in Baoding, China
Authors: Zhang Xutao , Gao Yuefen , Shi Guohua
Published: January 2011

As we know, more and more energy are required to meet the demands of society, and this has forced the government to review the economy and energy policies. The solar energy resource is abundant in China, which provides a good foundation with the utilization of solar energy. In China, there is a Silica Valley in Beijing, an Optics Valley in Wuhan, and also an Electricity Valley in Baoding. First, the only domestic national industry base of renewable energy and equipment is located in Baoding National New and High-tech Industry Zone. Secondly, there are great advantages on the photovoltaic industry, the wind power generation and the power transmission and transformation equipment, corresponded with the Yingli Green Energy Holding Company Limited, Zhong Hang Huiteng Wind Power Equipment Corporation Limited and Tian Wei Group Corporation Limited, respectively. Then it is a natural choice for the local government to develop the renewable energy in the readjustment of industry structures. This paper deals with the utilizations and prospects of solar energy.
Minimizing On-Peak and Off-Peak Demands for a Thermal Storage System: Forecast Model Analysis to Predict Next Day Daily Average Load and Model Application
Authors: Song Li , Joo Ik-Seong , Gunawan Subroto
Published: January 2011

Thermal storage systems were originally designed to shift on-peak cooling production to off-peak cooling production to reduce on-peak electricity demand. Recently, however, the reduction of both on- and off-peak demands is becoming an exceedingly important issue. Reduction of on- and off-peak demands can also extend the life span and defer or eliminate the replacement of power transformers due to potential shortage of building power capacity caused by anticipated equipment load increases. Next day daily average electricity demand is a critical set point to operate chillers and associated pumps at the appropriate time. For this paper, a mathematical analysis of the annual daily average cooling of a building was conducted, and three real-time building load forecasting models were developed: a first-order autoregressive model, a random walk model, and a linear regression model. A comparison of results shows that the random walk model provides the best forecast. A complete control algorithm integrated with forecast model for a chiller plant including chillers, thermal storage system and pumping systems was developed to verify the feasibility of applying this algorithm in the building automation system. Application results are introduced in this paper as well.
Performance Modeling of an Air-Based Photovoltaic/Thermal (PV/T) Collector
Authors: Casey Ross D. , Brandemuehl Michael J. , Merrigan Tim , Burch Jay
Published: January 2011

This paper studies a collector design that utilizes unglazed photovoltaic/thermal (PV/T) collectors preheating air for glazed air heating modules. The performance modeling of these collectors is examined both individually and in series. For each collector type, a dynamic, finite difference, first-law model has been created using literature correlations for friction. The models were compared to performance data, calibrating the models by scaling of friction terms for best fit. The calibrated models generally agree well with the experimental data; even during sudden changes to ambient conditions. The root mean square error between the unglazed PV/T model and experiment results for the useful thermal energy gain and the outlet air temperature are 7.12 W/m2 and 1.07°C, respectively. The annual source energy performance of the building-integrated PV/T (BIPV/T) array is then simulated for residential applications in seven climate zones of the United States of America. The performance of the BIPV/T array is characterized by the amount of net electrical energy and useful thermal energy produced. The useful thermal energy is defined as the amount of energy offset by the BIPV/T system for water heating and space conditioning. A BIPV/T system composed 87.5% of PV modules, and 12.5% of glazed air heating modules, offsets the same amount of source energy as a roof-mounted PV system of the same area. This array composition increases the thermal energy gain by 47% over a BIPV/T array composed solely of PV modules.
Lessons Learned From 30 Years Experience With Renewable Energy Technologies at Fort Huachuca, Arizona
Authors: Stein William J. , Ducey Roch A. , Johnson Bruce R.
Published: January 2011

Fort Huachuca, AZ, located 60 mi Southeast of Tucson, has had over 30 years of experience with various renewable energy systems. This session discusses lessons learned from the successes and failures in that experience, including: an indoor pool solar water heating system (installed 1980); a solar domestic hot water (DHW) system (installed 1981); a grid connected Photovoltaic system (installed 1982); transpired air solar collectors (Solarwalls,™ installed 2001); day-lighting (installed 2001); a 10-KW wind turbine (installed 2002); photovoltaic powered outdoor lighting (installed 1994); a prototype Dish/Stirling solar thermal electric generator (installed 1996); two 30-KW Building Integrated Photovoltaic systems (installed on new membrane roofs in 2009); and a 36-KW Photovoltaic system moved from the Pentagon in June 2009 and became operational November 2009 at Fort Huachuca. Also discussed is an experimental solar attic system (first installed in 2003 and now being fully monitored) that collects hot air in an attic, and via a heat exchanger and tank, produces solar DHW. This paper discusses system design, installation, metering, operation and maintenance, and also work in progress on the installation of commercial, off-the-shelf 3-KW Dish/Stirling solar thermal electric generators and solar thermal/natural gas-to-electric systems at a central plant. Discussions include biogas (methane from a wastewater digester) and biomass (wood chip boiler) being installed at a central heating/cooling plant.
Exposure of Polymeric Glazing Materials Using NREL’s Ultra-Accelerated Weathering System (UAWs)
Authors: Bingham Carl , Jorgensen Gary , Wylie Amy
Published: January 2011

NREL’s Ultra-Accelerated Weathering System (UAWS) selectively reflects and concentrates natural sunlight ultraviolet irradiance below 475 nm onto exposed samples to provide accelerated weathering of materials while keeping samples within realistic temperature limits. This paper will explain the design and implementation of the UAWS which allow it to simulate the effect of years of weathering in weeks of exposure. Exposure chamber design and instrumentation will be discussed for both a prototype UAWS used to test glazing samples as well as a commercial version of UAWS. Candidate polymeric glazing materials have been subjected to accelerated exposure testing at a light intensity level of up to 50 UV suns for an equivalent outdoor exposure in Miami, FL exceeding 15 years. Samples include an impact modified acrylic, fiberglass, and polycarbonate having several thin UV-screening coatings. Concurrent exposure is carried out for identical sample sets at two different temperatures to allow thermal effects to be quantified along with resistance to UV.
Instrumentation and Simulation of the Hygro-Thermal Conditions of a Green Building: A Study of the Impact of the Post-Occupancy Usages on Thermal Comfort
Authors: Lucas Franck , Perouzel Jean , Sinama Frantz , Garde Franc¸ois
Published: January 2011

Post-occupancy evaluations (POEs) are useful for evaluating the success of any building design, but are particularly useful in evaluating green buildings. It is the only opportunity architects and engineers have to learn if their buildings actually work as planned. On the other hand, following the “guidebook” of a green building, i.e. having occupants aware of the particularity of the premise and taught about how it works and what the proper usages are (which are not automatically straightforward), is of prime importance since misuse of a green building can directly lead to discomfort and energy over consumption. In that framework, this paper stresses the link between occupants’ usages and their indoor thermal comfort by attempting a quantification of the impact of each usage on indoor temperature and hygrometry (and thus thermal comfort), showing by the way that, in order a POE to fully give exploitable results, a communication to occupants on proper usages has to be the first step after the delivery of a green building. To study that link, the real case of a green building located in the French tropical island of La Re´union has been used. The overall idea followed in this work lies in two steps: The first one is the creation of a “validated” digital building description obtained thanks to a process of comparison between simulations outputs (DesignBuilder) and field measurements (weather and comfort stations), and to a “block by block” approach that allows independent validations of the description of the fabrics and of the description of the usages. The second step is the utilization of the model obtained in the first step to perform simulations of new usages, as modifications in natural ventilation features (doors, windows open or closed) or in number of occupants, lighting schedule etc. These new simulations lead to the possibilities of comparing situations between each others, and therefore of quantifying the contribution, positive or negative, of each chosen usage to thermal comfort. Eventually, this paper will describe an example of combination of new usages that makes the conditions noticeably more comfortable within the building, stressing that following the good usages in a green building is a first requirement before realizing any POE.
A New Design for Cassino Hexapod Robot
Authors: Nava Rodri´guez Nestor Eduardo , Moreno Lorente Luis , Carbone Giuseppe , Ceccarelli Marco
Published: January 2011

We present the design process of a new low-cost easy-operation Cassino Hexapod robot. In a recent past, research activities have been carried out for developing a six-legged robot at LARM (LAboratory of Robotics and Mechatronics) of Cassino University in Italy. The robot designs have been based on suitable mechanism structures and architectures that can be easy operated by a commercial on-off logic device. The first prototype is composed of modular legs with three degrees of freedom (DOF). A second prototype of a hexapod leg presents two links and two DOFs. The new prototype Cassino Hexapod robot has two DOFs, such as, one for pitch movement that drives an articulated mechanism and other for yaw movement. Additional peculiarity of the leg design is that the foot is designed as a powered wheel with the possibility to regulate the velocity and force at the contact during the support phases of the leg. Simulation results of the proposed design operation of the new hexapod robot are reported with the aim of characterizing both operation performance and design features.
An Effect of Plastic Anisotropy on the Strain Rate Intensity Factor
Authors: Alexandrov Sergei
Published: January 2011

The strain rate intensity factor in the theory of rigid perfectly plastic isotropic materials is the coefficient of the principal singular term in a series expansion of the equivalent strain rate in the vicinity of maximum friction surfaces. This coefficient can be used to predict the evolution of material properties in a narrow layer in the vicinity of surfaces where the friction stress is high. Usually, conventional evolution equations are not compatible with the plasticity equations near maximum friction surfaces. It is therefore of interest to extend the theories based on the strain rate intensity factor to more general models than the rigid perfectly plastic isotropic solids. The present paper deals with plane strain deformation of rigid plastic anisotropic material. It is shown by means of a simple analytic solution that the velocity field is singular in the vicinity of maximum friction surfaces. Thus the strain rate intensity factor can be introduced for such materials. An effect of plastic anisotropy on its value is demonstrated. In addition, it is shown that rigid plastic solutions for anisotropic materials can exhibit various types of singularity in the vicinity of maximum friction surfaces, in contrast to isotropic materials where one type only is possible. Nevertheless, in most cases the type of singularity is same for isotropic and anisotropic materials.
Life Cycle Cost Modeling of Pumps Using an Activity Based Costing Methodology
Authors: Waghmode Laxman Yadu , Sahasrabudhe Anil Dattatraya
Published: January 2011

In order to survive in today’s competitive global business environment, implementation of life cycle costing methodology with a greater emphasis on cost control could be one of the convincing approaches for the manufacturing firms. The product life cycle costing approach can help track and analyse the cost implications associated with each phase of product life cycle. Life cycle costing (LCC) practices with traditional costing methods may provide results that have a severe deviation from the real product LCC as it focuses on the cost of materials, labor and a low portion of overheads apportioned by the absorption rate to the product. Activity based costing (ABC) has emerged as one of the several innovative and more accurate costing methods in recent years. It is based on the principle that products or services consume activities and activities consume resources that generate costs. Thus, the ABC system focuses on calculating the costs incurred on performing the activities to manufacture a product. This paper presents a LCC modeling approach for estimating life cycle cost of pumps using activity based costing method. The study was conducted in a large pump manufacturing company from India that has significant global standing within its industry. Firstly, all the activities and cost drivers associated with the life cycle of a pump have been identified. A methodology for LCC analysis using ABC is then developed and it is applied to two different pumps manufactured by the same industry and the results obtained are presented.
Computational Study of Hydrogen Storage Performance in Metal Hydride Reactors
Authors: Chung Chih-Ang , Lin Ci-Siang , Ho Ci-Jyun
Published: January 2011

Hydrogen as the most abundant element on Earth is viewed to be a promising energy carrier. For transmission, hydrogen stored as metal hydrides is a potent candidate for its advantages in safe and reliability and being able to offer high energy density compared to the conventional ways such as high pressure gas and liquefaction. Metal hydriding is basically an exothermic process. The heat released will cause an increase in temperature and raise the absorption equilibrium pressure as high as that of the supplied hydrogen gas, which may in turn stop the hydriding process. On the other hand, metal dehydriding is an endothermic process. A temperature decrease can retard desorption and even bring down the dissociation equilibrium pressure as low as the back pressure to stop dehydriding. Therefore, reducing thermal resistance of the storage vessels and enhancing heat transfer of the storage system have become a critical issue for the success of hydrogen storage using metal hydrides. This work models the metal hydriding/dehydriding process in order to assess the vessel design on heat transfer enhancement to improve the performance of hydrogen storage with metal hydrides. First of all, the thermal-fluid behavior of hydrogen storage was modeled including gas flow and energy equations. The vessel is considered to be equipped with an air pipe at the centre line with internal fins. Detailed theoretical models that describe force convection of the heat exchange pipe and natural convection at the lateral wall are constructed. Results from the simulation show that the addition of a concentric heat exchanger pipe with fins can enhance the reaction rates. The work demonstrates how computer aided engineering can be applied to evaluate the performance of hydrogen storage designs, and help reduce experimental efforts in developing the hydrogen storage systems.
Life and Wear Prediction of Twist Drills by a Temperature Dependent Friction Law
Authors: Vaghefpour Hossein , Nayebi Ali
Published: January 2011

This paper describes the material flow in shear zone by using a thermo mechanical model. The material is an isotropic, viscoplastic rigid material; its behavior is described by a J–C law. The contact length between the chip and the tool and the temperature distribution at the tool–chip interface which has an important effect on the tool wear. Using the thermo-mechanical model and the temperature friction law, the tangential forces, friction coefficient and contact length on the cutting element as a function of radius, for different feed rate and cutting speed, are obtained. The results of proposed model are compared with experimental results and good agreement is obtained.
Experimental Study of Free Convection Heat Transfer From a Fin Attached Cylinder Confined Between Tilt and Low Conductive Plates
Authors: Rezaei Amir Abbas , Ziabasharhagh Masoud , Yousefi Tooraj , Ahmadi Mehran
Published: January 2011

Steady state and two-dimensional natural convection heat transfer flow around a horizontal and isothermal cylinder with a longitudinal fin attached to it that is located between two tilt and very low conductive plates is studied experimentally by using a Mach-Zehnder interferometer. Effects of the plates slope angel (θ) on heat transfer from the tube is investigated for Rayleigh number ranging from 1000 to 15500. Experiments are done for a fin attached cylinder placed between two low conductive plates. Two different diameter tubes with diameters of D=10 and 20mm are utilized for broad Rayleigh number range. Results specify that, heat transfer experience differs for special Rayleigh numbers. For Rayleigh numbers ranging less than 5500, rate of heat transfer amount from the cylinder surface is less than that of a lone cylinder and it’s the result of no slip boundary condition on the fin surface. For this range of Rayleigh number by the use of plates, heat transfer from the cylinder surface decreases slightly and plates leaning does not alter heat transfer speed from the cylinder surface. For Rayleigh number ranging from 5500 to 15500, heat transfer rate from the cylinder surface is lower than the heat transfer rate from the surface of an individual cylinder. Though, by adding placing the low conductive plates as plates to experimental model, heat transfer system differs and chimney effect between fin and the plates increases the heat transfer from the cylinder surface. By increasing the plates slope angel from 0° to 20°, the chimney effect between plates and fin weakens and heat transfer rate from the tube surface is going to the amount of heat transfer rate from a fin attached cylinder which is not placed between plates.
Compressible Fluid Flow Simulation Using Finite Difference Lattice Boltzmann Method
Authors: Abdollahi Vahid , Nejat Amir
Published: January 2011

A finite difference lattice Boltzmann method (FDLBM) is employed to simulate the compressible inviscid/viscous flows. The robustness of the employed approach is tested for the shock tube or Riemann problem in some distinct cases including strong pressure shock, the stationary contact discontinuity and the weak acoustic wave. The Results are compared with the exact solutions, as well as other classical finite volume CFD techniques (Steger-Warming, Roe and AUSM flux). The validity of the employed LBM approach is studied. This research reveals some of the challenges involved in simulating the compressible flows using FDLBM.
Experimental Study of Turbulence Across the Fractal Orifice Plate
Authors: Salim S. M. Muztaba , Nicolleau Franck C. G. A. , Beck Stephen B. M. , Nowakowski Andrzej F.
Published: January 2011

An experimental study of turbulence behind a fractal orifice plate, a variant of classical circular orifice plate, was conducted in a circular wind tunnel. Four fractal orifice plates with iteration levels from zero to three in combination with a classical circular orifice plate, each with equal flow area, were used in the study. Of the two main objectives, the first one was to test the superiority of the proposed fractal orifice plate against the classical one and the second one was to investigate the fractal orifice effect on the flow properties. Across the fractal orifice plate, a decrease in the pressure drop and an increase in the flow mixing is observed making it much more efficient than the classical orifice plate. It was suggested that at each fractal iteration, the added edge sharpness generated finer flow structures and these flow structures were eventually responsible for the improved efficiency.
Incorporating Residual Stresses Into Thermo-Mechanical Fatigue Analysis of Cylinder Head
Authors: Erpolat Serhat , Manav Demirhan , Tekeli Alper , Sever Cagri
Published: January 2011

Residual stresses are one of the key factors affecting fatigue durability of important cast parts such as cylinder head and engine block. In automotive industry, general approach is to incorporate residual stresses into durability analysis by simply superposing the values by means of a fatigue post-processor. Residual stresses elevate or decrease the mean stress value according to whether stress states are tensile or compressive. However, it is thought that uncoupling two analyses may lead to misleading results. Instead, a single analysis should incorporate residual stress and thermo-mechanical analysis steps, one after the other. This is a comparative study for these two approaches and shows that assumption of a virgin material at the beginning of thermo-mechanical analysis is not always valid although two approaches agrees well with each other for moderate loading levels.
ISWEC: Design of a Prototype Model for Wave Tank Test
Authors: Bracco Giovanni , Giorcelli Ermanno , Mattiazzo Giuliana
Published: January 2011

The extraction of energy from ocean waves has been investigated in Europe since the 1970s. During the research process hundreds of devices have been proposed and a few of them have been built full scale and deployed to the ocean. Unlike other renewable energies, so far there has not been a device standing out to be the most suitable to exploit wave power. One of the practical problems to be solved in a Wave Energy Converter (WEC) is durability in the harsh marine environment. This could be critical if parts of the converter such as turbine rotors or auxiliary floats are needed to move or to react while exposed to seawater and spray. One method to solve the problem is to use a WEC composed just by one sealed floating body carrying a gyroscope. The inertial effects of the gyroscope are activated by the float motion and are used to drive a generator. The whole system operates in the clean environment inside the float. In this work a procedure to design the ISWEC device (Inertial Sea Wave Energy Converter) is outlined. The mechanical equations describing the system are linearized, studied in the frequency domain and used as a mathematical tool in the design process. The method is then applied iteratively to design a scaled prototype model to be tested in the wave tank at the University of Naples. The final version of the prototype model is then scaled up to evaluate the performances of a full scale device.
On the Dynamic Contact Problem for a Viscoelastic Plate
Authors: Bock Igor
Published: January 2011

We deal with an initial-boundary value problem describing the perpendicular vibrations of an anisotropic viscoelastic plate free on its boundary and with a rigid inner obstacle. A weak formulation of the problem is in the form of the hyperbolic variational inequality. We solve the problem using the discretizing the time variable. The elliptic variational inequalities for every time level are uniquely solved. We derive the a priori estimates and the convergence of the sequence of segment line functions to a variational solution of the considered problem.
Application of Ethics Criteria to Engineering Profession: Case Study of Engineering Students at the UAE University
Authors: Selim Mohamed Y. E. , Al-Bayywomi Mohamed A.
Published: January 2011

An investigation has been carried out to examine the level of engineering ethics for senior engineering graduating students. The ethical response to some educational and engineering dilemmas for the graduating students has been collected with a questionnaire designed for this purpose. Dilemmas included educational ones that students see every day in their educational life and professional situations that they are to face upon graduation. Educational dilemmas included many situations such as: their behavior at the university, their selection of the engineering discipline, exam time behavior and honesty with colleagues and instructors. Professional dilemmas included their behavior with their colleagues, behavior with their manager, with customers, with deadlines, with free and paid consultations, with life long learning, with efforts-salary relation and with indirect bribery. Students’ response with respect to all dilemmas and on projection to the professional standards are presented and analyzed. It has been shown that exposing students to such dilemmas could be a useful learning tool for engineering ethics.
Design of a Cost Effective Haptic Interface
Authors: Bracco Giovanni , Giorcelli Ermanno , Mattiazzo Giuliana , Romano` Carlo , Sorli Massimo
Published: January 2011

Haptic interfaces are human machine interface devices used for giving feedback sensations to an operator; they are used in a wide range of applications, like aeronautic fields, remote operation of manipulators in hostile or dangerous environments, and recently also for micro assembly machines and new surgery equipments. The major advantage of this technology is the improved performance of the operator himself, in fact it has been proven that having tactile sensation combined with visual information shortens reaction time. In this paper the authors show the process used to build a prototype of a master for tele-operation with force feedback on the operator. Once specifications on nominal force, bandwidth and angular displacement of the stick were established, a comparison between different kinematic solutions was carried out and a differential drive train was chosen as the core of the device. A linear dynamic model was then developed in order to predict system behaviour and estimate its main parameters. The dynamic analysis shows that the designed joystick can achieve the design parameters.
Investigation of Frictional Resistance in Nanometric Cutting by Molecular Dynamic Simulation
Authors: Hosseini Seyed Vahid , Vahdati Mehrdad
Published: January 2011

Recently, the development of machine tools and sub-micron positioning control systems has brought the minimum thickness of ultra-precision cutting to less than 1 nm. The conventional continuum based method (FEM) becomes impossible to use for numerical analysis. As an alternative method, molecular dynamics (MD) method is significantly implemented in the field of nano-machining to investigate cutting mechanism. In this paper, firstly, molecular dynamics simulations of the nanometric cutting of single-crystal copper were performed applying a pin tool. The model was solved with both Morse and Embedded Atom Method (EAM) potential functions to simulate the interatomic force between the work piece and a rigid tool. The nature of material removal, chip formation, and frictional forces were simulated. In order to investigate the coefficient resistance (the ratio of the cutting force to the thrust force), some MD simulations also carried for various cutting velocity and cutting depths. The results show that the Morse potential and EAM method have some difference to model tool forces and frictional resistance. Also, surface properties and atomic displacement in each of these potential functions have some discrepancy. In addition, cutting and trust forces increase with the cutting velocity and the depth of cut, however the effect of cutting speed is not very significant. Finally the value of frictional resistance is not changed with similar tool for various cutting speeds.
Numerical and Experimental Studies of High Strain Rate Mechanical Behavior of E-Glass/Polyester Composite Laminates
Authors: Tunusoglu Gozde , Tasdemirci Alper , Guden Mustafa , Hall I. W.
Published: January 2011

Quasi-static (∼10−3 s−1) and high strain rate (∼850 s−1) compression behavior of an E-glass/polyester composite was determined in the through-thickness and in-plane directions. In both directions, modulus and failure strength increased with increasing strain rate. Higher strain rate sensitivity for both elastic modulus and failure strength was observed in the inplane direction. A numerical model was developed to investigate the compressive deformation and fracture of an E-glass/polyester composite. Excellent agreement was demonstrated for the case of high strain rate loading. Also, the fracture geometries were successfully predicted with the numerical model.
Dynamic Modeling and Analysis of a 3 PRS Parallel Mechanism Using Constrained Robotic Approach
Authors: Tsai Meng-Shiun , Yuan Wei-Hsiung
Published: January 2011

In this paper, a novel model is developed to analyze a 3-PRS parallel mechanism. The 3-PRS mechanism consists of a moving platform which is manipulated by three actuated fingers. Since the fingertips are constrained by the moving platform, three holonomic constraint equations are derived and the associated constraint forces are studied based on the theory of differential geometry. The developed model could be utilized to separate the dynamics of the fingers and that of the moving platform such that the coupling behaviors of the fingers can be investigated. It is found that the reaction forces applied at the fingertips of the parallel manipulator include not only the driving forces to the moving platform but also the constraint forces. Besides, the constraint forces are determined to be internal forces which would not generate a net force or torque to drive the moving platform. Simulations are performed to study the dynamic behavior of the reaction forces and it is found that the constraint forces have significant effect on the actuated fingers.
Control and Manipulation of Multibody Objects
Authors: Beigzadeh Borhan , Meghdari Ali , Sohrabpour Saeed
Published: January 2011

In this work, we study a kind of manipulation process during which we deal with active objects. An active object is a concept covering a variety of objects that are not rigid and need to be controlled during the manipulation process. Here, we use a multi-link mechanism with active motors (actuator) as the object and a series of simple planar manipulators to perform the manipulation process. Dynamic, control, motion planning, and stability at the presence of impact are the most important challenges in this work.
Design and Fuzzy Control of the Shark Robot-Fish Dorsal Fin Using SMA
Authors: Aghbali Behnam , Yousefi-Koma Aghil
Published: January 2011

This contribution presents the experimental investigations on design and fabrication of the dorsal fin of the shark robot-fish mechanism which is controlled using NiTi Shape Memory Alloy (SMA) actuators by a Fuzzy controller. The dorsal fin helps the shark not only to turn around, but also it helps shark to roll. This fin contains two main parts, a rigid part; is connected to the shark’s body and another part is mounted on the latter one which can be rotated. The rotation angle of the second part is controlled by two parallel SMA wires. The subtlety of this installation is the tension of the right wire, when the left one is actuated. In addition, a fuzzy controller was determined by considering the characteristics of the SMA wires and designated mechanism which has hysteresis response characteristics against heating and cooling.
The Virtual Laboratory of Program Control
Authors: Kostal Peter , Mudrikova Andrea , Caganova Dagmar
Published: January 2011

In this paper is described the main ideas of national project “KEGA 3/7131/09 – Laboratory of production system program control”. This project is focused to build of virtual laboratory and supplemental e-learning documents for several studying subject at our institute. This project being solved in the Institute of Production Systems and Applied Mechanics, Faculty of Materials Science and Technology – STU in years 2009–2011 includes an opportunity to acquire and improve abilities and skills the employers expect technical university graduates to have. The project target is to create a virtual laboratory of programmable control systems and a suitable teaching system supporting creation and improvement of key and occupational competences, abilities and skills of students in technical fields of study promoting at the same time their preparation for practice and lifelong education.
Exergy, Cost and Environment as Objectives in Particle Swarm Optimization of a Benchmark Cogeneration System
Authors: Babaie Meisam , Sayyaadi Hoseyn , Farmani Mohammad Reza , Novinzadeh Alireza
Published: January 2011

Multi-Objective Optimization of a benchmark cogeneration problem known as CGAM cogeneration system has been carried out from Exergetic, Economic and Environmental aspects simultaneously. CGAM Problem designs a cogeneration plant which delivers 30 MW of electricity and 14 kg/s of saturated steam at 20 bars. Since multi-objective calculus based optimization of real energy systems involves very complicated process, one of the most suitable techniques which uses a particular class of search algorithms known as Particle Swarm Optimization (MOPSO) is utilized and the advantages of this method is shown. This approach has been applied to find the set of Pareto optimal solutions with respect to the competing objective functions. In this study the MOPSO algorithm uses 100 particles and 200 iterations. In order to facilitate the problem, the environmental objective function has been defined and expressed in cost terms. The thermodynamic modeling has been implemented comprehensively while economic analysis of this system conducted. Consideration of Five decision variables in modeling process made the final optimal solutions more realistic in comparison with previous studies in this field. Finally the result of optimization is introduced with 100 points on Pareto frontier.
Airfoil Flow Separation and Stall Prediction Using a Neural-Network Approach
Authors: Nejat Amir , Alem Varzaneh Esfehani Saeed , Doostmohammadi Amin
Published: January 2011

An Artificial Neural Network approach is applied to predict the lift coefficient of the airfoil for different angles of attack at the specified Reynolds number for airfoils with different shape characteristics. The Stall of the airfoil is characterized by a sudden drop in the lift force caused by flow separation. Therefore by prediction of the lift coefficient for different angles of attack and via determining its maximum, the stall angle for a specific shape of the airfoil can be determined. The Computational Fluid Dynamics is used to provide the initial data needed for ANN training; the lift coefficient of the airfoil for the range of angles of attack is taken as a target and NACA0012 is considered as a base line model in the present study. The profile of the airfoil is constructed by Be´zier curves with eight control points and these control points along angles of attack are adopted as the training data for the Artificial Neural Network training. The ANN results are compared with those obtained by CFD. The results show the ANN approach can accurately predict the lift coefficient for the preliminary design process at substantially lower computational cost.
An ANN Approach on the Optimization of the Cutting Parameters During CNC Plasma-Arc Cutting
Authors: Kechagias John , Pappas Menelaos , Karagiannis Stefanos , Petropoulos George , Iakovakis Vassilis , Maropoulos Stergios
Published: January 2011

The objective of the present study is to develop an Artificial Neural Network (ANN) in order to predict the bevel angle (response variable) during CNC plasma-arc cutting of St37 mild steel plates. The four (4) input parameters (plate thickness, cutting speed, arc ampere, and torch standoff distance) of the ANN was selected following the results (relative importance) of the Analysis Of Variance (ANOVA) performed based on seven (7) factors (plate thickness, cutting speed, arc ampere, arc voltage, air pressure, pierce height, and torch standoff distance) in a previous study. A multi-parameter optimization was carried out using the robust design. An L18 (21 × 37) Taguchi orthogonal array experiment was conducted and the right bevel angle was measured, aiming at the investigation of the influence of plasma-arc cut process parameters on right side bevel angle of St37 mild steel cut surface. The selection of quality characteristics, material, plate thickness and other process parameter levels and experimental limits was based on the experience and current needs of the Greek machining industry. A feed-forward backpropagation (FFBP) neural network was fitted on the experimental data. The results show that accurate predictions of the bevel angle can be achieved inside the experimental region, through the trained FFBP-ANN. The developed ANN model could be further used for the optimization of the cutting parameters during CNC plasma-arc cutting.
Exergy Analysis of Steel Electric Arc Furnace
Authors: Hajidavalloo Ebrahim , Dashti Hamzeh
Published: January 2011

In this paper, energy and exergy analysis of an existing steel electric arc furnace (EAF) was performed to estimate the furnace potential for increasing the efficiency and decreasing the electrical energy consumption. The results of analysis show that the energy and exergy efficiencies of the furnace are 56.9% and 40.5%, respectively. Field data show that mass flow rate of hot flue gas is around 10.4 kg/s in average which contains 18.3% and 12.2% of total input energy and exergy, respectively. By using energy of flue gas for preheating the sponge iron, electrical energy consumption of the furnace could be reduced up to 88 GJ which means 21.2% reduction in electrical energy consumption and 13.6% increase in steel production. Also, exergy efficiency improves about 10.8% by using preheating scheme.
An Empirical Study on Heat Transfer Characteristics of CuO/Base Oil Nanofluid Flow in a Tube With Coiled Wire Inserts
Authors: Akhavan-Behabadi M. A. , Saeedinia M. , Hashemi S. M.
Published: January 2011

In the present study, an experimental investigation has been carried out to study the heat transfer characteristics of CuO/Base oil nanofluid flow inside horizontal oiled wire inserted tubes (roughed tubes) under constant heat flux. The nanofluids with CuO nanoparticles weight fraction ranging from 0 to 2% are prepared. The oiled wires with different wire wire diameteres and different oil pitches are used as inserts inside a horizontal plain copper tube. The nanofluid flowing inside the tube is heated by electrical heating coil wrapped around it. The convective heat transfer characteristis of the prepared nanofluids are measured during laminar fully developed flow inside horizontal plain and roughed tubes under constant heat flux. The effect of different parameters such as mass velocity, wire wire diameter, oil pith, nanofluid particles concentration and heat flux on heat transfer coefficient is studied. The heat transfer coefficient is increased when a roughed tube is used instead of a plain tube. Moreover, at the same flow conditions, by increasing of wire wire diameter and decreasing of oil pitch, the heat transfer performance is improved. Observations also show that by using nanofluid instead of base fluid, the heat transfer coefficient increases and this increase grows at higher nanoparticles concentrations. As a result, it an be concluded that increasing of wire wire diameter, decreasing of oil pitch and increasing the concentration of nanoparticle, contribute to the enhancement of heat transfer coefficient.
Gain Scheduling Fuzzy Sliding Mode Strategy for Robotic Motion Control
Authors: Huang Shiuh-Jer , Wu Shian-Shin , Huang You-Min
Published: January 2011

A Mitsubishi Movemaster RV-M2 robotic system control system is retrofitted into system-on-programmable-chip (SOPC) control structure. The software embedded in Altera Nios II field programmable gate array (FPGA) micro processor has the functions of using UART to communicate with PC, robotic inverse kinematics calculation, and robotic motion control. The digital hardware circuits with encoder decoding, limit switch detecting, pulse width modulation (PWM) generating functions are designed by using Verilog language. Since the robotic dynamics has complicate nonlinear behavior, it is impossible to design a MIMO model-based controller on micro-processor. Here a novel model-free fuzzy sliding mode control with gain scheduling strategy is developed to design the robotic joint controller. This fuzzy controller is easy to implement with 1D fuzzy control rule and less trial-and-error parameters searching work. The experimental results show that this intelligent controller can achieve quick transient response and precise steady state accuracy for industrial applications.
Large Deflection of a Non-Linear, Elastic, Asymmetric Ludwick Cantilever Beam
Authors: Borboni Alberto , De Santis Diego , Faglia Rodolfo
Published: January 2011

The investigated cantilever beam is characterized by a constant rectangular cross-section and is subjected to a concentrated vertical constant load at the free end. The same beam is made by an elastic non-linear asymmetric Ludwick type material with different behavior in tension and compression. Namely the constitutive law of the proposed material is characterized by two different elastic moduli and two different strain exponential coefficients. The aim of this study is to describe the deformation of the beam neutral surface and particularly the horizontal and vertical displacements of the free end cross-section. The analysis of large deflection is based on the Euler-Bernoulli bending beam theory, for which cross-sections, after the deformation, remain plain and perpendicular to the neutral surface; furthermore their shape and area do not change. On the stress viewpoint, the shear stress effect and the axial force effect are considered negligible in comparison with the bending effect. The mechanical model deduced from the identified hypotheses includes two kind of non-linearity: the first due to the material and the latter due to large deformations. The mathematical problem associated with the mechanical model, i.e. to compute the bending deformations, consists in solving a non-linear algebraic system and a non-liner second order ordinary differential equation. Thus a numerical algorithm is developed and some examples of specific results are shown in this paper. Precisely, the proposed problem is a generalization of similar cases in literature, consequently numerical comparisons are performed with these previous works, i.e. assuming linear elastic materials or assuming symmetric Ludwick type material with same behavior in tension and compression like aluminum alloy and annealed copper. After verifying a proper agreeing with the literature, in order to investigate the effect of the different material behavior on the horizontal and vertical displacements of the free end cross-section, numerical results are obtained for different values of elastic moduli and strain exponential coefficients. The arising conclusions are coherent with the assumed hypotheses and with similar works in literature.