bluuebunny/crossref_metadata_2025 huggingface dataset:
Mapping Study to Characterize NSCR Performance on a Natural Gas-Fueled Engine
Authors: Toema Mohamed , Nuss-Warren Sarah , Chapman Kirby S. , McCarthy James , McGrath Thomas
Published: August 2009

Kansas State University’s National Gas Machinery Laboratory and Innovative Environmental Solutions, Inc. are conducting a project to characterize pollutant emissions performance of field gas-fired four-stroke cycle rich burn (4SCRB) engines equipped with non-selective catalytic reduction (NSCR) technology. Engine emissions and operating parameters are being monitored on three engines over an extended period. In addition, a mapping study was conducted on one engine. The NSCR was operated at various controlled air-to-fuel ratios (AF) while emission measurements were conducted and engine operating parameters monitored. NOx, CO, and oxygen were measured using both EPA reference method technology and the portable analyzer used in the long-term study. In the mapping study, ammonia, formaldehyde, and speciated hydrocarbon emissions were recorded in real-time using an extractive FTIR system. This paper focuses on the engine mapping phase. The mapping tests demonstrated a trade-off between NOx emissions and CO, ammonia, and hydrocarbon emissions. Richer engine operation (lower AF) decreases NOx emissions at the expense of higher CO, ammonia, and hydrocarbons. Leaner operation has the opposite effect. The results to date of the semi-continuous monitoring are presented in a separate paper.
Parameter Based Combustion Model for Large Pre-Chamber Gas Engines
Authors: Zhu Jianguo , Wimmer Andreas , Schneßl Eduard , Winter Hubert , Chmela Franz
Published: August 2009

Challenging requirements for modern large engines regarding power output, fuel consumption and emissions can only be achieved with carefully adapted combustion systems. With the improvement of simulation methods simulation work is playing a more and more important role for the engine development. Due to their simplicity and short computing time, one-dimensional and zero-dimensional calculation methods are widely applied for the engine cycle simulation and optimization. While the gas dynamic processes in the intake and exhaust system can already be simulated with sufficient precision, it still represents a considerable difficulty to predict the combustion process exactly. In this contribution, an empirical combustion model for large pre-chamber gas engines is presented, which was evolved based on measurements on a single cylinder research engine using the DOE (Design of Experiments) method. The combustion process in pre-chamber gas engines is investigated and reproduced successfully by means of a Double-Vibe function. The mathematical relationship between the engine operating parameters and the parameters of the Double-Vibe function was determined as a transfer model on the base of comprehensive measurements. The effects of engine operating parameters e.g. boost pressure, charge temperature, ignition timing, air/fuel ratio on the combustion process are taken into account in the transfer model. After adding modification functions, the model can be applied to gas engines operated with various gas fuels taking into account the actual air humidity. Comprehensive verifications were conducted on a single cylinder engine as well as on full scale engines. With the combination of the combustion model and a gas exchange simulation model the engine performance has been predicted satisfactorily. Due to the simple phenomenological structure of the model, a user-friendly model application and a short computing time is achieved.
Ignition in Pilot-Ignited Natural Gas Low Temperature Combustion: Multi-Zone Modeling and Experimental Results
Authors: Krishnan Sundar Rajan , Srinivasan Kalyan Kumar , Midkiff Kenneth Clark
Published: August 2009

In previous research conducted by the authors, the Advanced Low Pilot-Ignited Natural Gas (ALPING) combustion employing early injection of small (pilot) diesel sprays to ignite premixed natural gas-air mixtures was demonstrated to yield very low oxides of nitrogen (NOx) emissions and fuel conversion efficiencies comparable to conventional diesel and dual fuel engines. In addition, it was observed that ignition of the diesel-air mixture in ALPING combustion had a profound influence on the ensuing natural gas combustion, engine performance and emissions. This paper discusses experimental and predicted ignition behavior for ALPING combustion in a single-cylinder engine at a medium load (BMEP = 6 bar), engine speed of 1700 rpm, and intake manifold temperature (Tin) of 75°C. Two ignition models were used to simulate diesel ignition under ALPING conditions: (a) Arrhenius-type ignition models, and (b) the Shell autoignition model. To the authors’ knowledge, the Shell model has previously not been implemented in a multi-zone phenomenological combustion simulation to simulate diesel ignition. The effects of pilot injection timing and Tin on ignition processes were analyzed from measured and predicted ignition delay trends. Experimental ignition delays showed a nonlinear trend (increasing from 11 to 51.5 degrees) in the 20°–60° BTDC injection timing range. Arrhenius-type ignition models were found to be inadequate and only yielded linear trends over the injection timing range. Even the inclusion of an equivalence ratio term in Arrhenius-type models did not render them satisfactory for the purpose of modeling ALPING ignition. The Shell model, on the other hand, predicted ignition better over the entire range of injection timings compared to the Arrhenius-type ignition delay models and also captured ignition delay trends at Tin = 95°C and Tin = 105°C. Parametric studies of the Shell model showed that the parameter Ap3, which affects chain propagation reactions, was important under medium load ALPING conditions. With all other model parameters remaining at their original values and only Ap3 modified to 8 × 1011 (from its original value of 1 × 1013), the Shell model predictions closely matched experimental ignition delay trends at different injection timings and Tin.
Variations in Long-Term Emissions Data From NSCR-Equipped Natural Gas-Fueled Engine
Authors: Nuss-Warren Sarah , Toema Mohamed , Chapman Kirby S.
Published: August 2009

This paper describes work by Kansas State University’s National Gas Machinery Laboratory and Innovative Environmental Solutions, Inc. on a project to characterize pollutant emissions performance of non-selective catalytic reduction (NSCR) technology, including a catalyst and air-to-fuel ratio controller (AFRC), applied to four-stroke cycle rich-burn engines. Emissions and engine data were collected semi-continuously with a portable emissions analyzer on three engines in the Four Corners area. In addition, periodic emissions measurements that included ammonia were conducted several times. Data collected from October, 2007, through August, 2008, shows significant variation in emissions levels over hours, days, and longer periods of time, as well as seasonal variation. As a result of these variations, simultaneous control of NOx to below a few hundred parts per million (ppm) and CO to below 1,000 ppm volumetric concentration was not consistently achieved. Instead, the NSCR/AFRC systems were able to simultaneously control both species to these levels for only a fraction of the time the engines were monitored. Both semi-continuous emissions data and periodically collected emissions data support a NOx-CO trade-off and a NOx-ammonia tradeoff in NSCR-equipped engines.
Qualitative Study of Nanocluster Positioning Process: 2D Molecular Dynamics Simulations
Authors: Mahboobi S. H. , Meghdari A. , Jalili N. , Amiri F.
Published: August 2009

One of the key factors in the assembly of nanoclusters is the precise positioning of them by a manipulation system. Currently the size of clusters used as building blocks is shrinking down to a few nanometers. In such cases, the particle nature of matter plays an important role in the manipulator/cluster/substrate interactions. Having a deeper insight to the aforementioned nanoscale interactions is crucial for prediction and understanding of the behavior of nanoclusters during the positioning process. In the present research, 2D molecular dynamics simulations have been used to investigate such behaviors. Performing planar simulations can provide a fairly acceptable qualitative tool for our purpose while the computation time is greatly reduced in comparison to 3D simulations. The system consists of a tip, cluster and substrate. The focus of the present research is on ultra-fine metallic nanoclusters. To perform this research, Nose-Hoover dynamics and Sutton-Chen interatomic potential will be used to investigate the behavior of the above system which is made from different transition metals. The effects of material type, tip form and manipulation strategy on the success of the process have been investigated by planar molecular dynamics. Such qualitative simulation studies can evaluate the chance of success of a certain nanopositioning scenario regarding different working conditions before consuming large-scale computation time or high experimental expenses.
The Reaction of the Head and Neck to Blast Waves: Comparison to Blunt Impact
Authors: Harrigan Timothy P.
Published: August 2009

Due to the relatively large number of exposures to IED blasts in Iraq and Afghanistan, the mechanical effects of blast waves impinging on the head have become an area of high interest. The ways in which the physical aspects of blast loading can cause injury are controversial in some respects but a general consensus is forming that much of the knowledge from closed head injury due to blunt trauma can be applied to injury mechanisms in blast loading [2]. In particular, sudden head rotations are known to be significant, as these are connected to high strains in brain tissue, in much the same way that rotations applied to a jar full of gelatin can induce deformations in the gelatin. High strains induced by sudden rotations of the head are known to be significant in developing injuries to the white matter of the brain [3, 4]. This study used a coupled fluid-structure finite element model to assess the effects of blast over pressure on translation and rotation of the head due to blast wave exposure. A finite element model of a 5th percentile Hybrid-III dummy was used which was supplied by Livermore Scientific Technlogy Corp. (LSTC) as part of a license for LS-Dyna. The ALE formulation for fluid-structure coupling was used [1]. The sudden increase in head velocity is significant, but the sudden increases in rotation rates are small compared to those for some impacts. The increases in velocity and rotation rate due to the passage of the blast wave on the head of the dummy occur over a few milliseconds, and rotation becomes significant only after the neck loads become active, 15 to 20 milliseconds after blast wave impingement. These results indicate that efforts to modify the rotational velocity of the head in the reaction to a blast wave should act within 15 to 20 milliseconds of the blast.
Mathematical Analysis of Extension Ladder Flipperlock
Authors: Morse John S. , Paul David M.
Published: August 2009

Most extension ladders employ pivoting flylocks or rung locks to support the retractable fly section against the force of gravity. Such flylocks can be prone to a condition known as flipperlock, where the flipper or tongue of the flylock is held by friction and the fly section is prevented from retracting. A user may not be aware of this condition, which is metastable. A retraction of the ladder may occur in use, with accompanying injuries. The ability of a flylock to flipperlock can be analyzed mathematically. One key variable is the angle between the tangent of the flylock tongue and the perpendicular to a line connecting the flylock pivot point with the rung/flipper contact point. The other key variable is the coefficient of friction between the flipper and the rung. An equation is developed for the minimum force developed by the flipperlock condition. The design features necessary to reduce the incidence of false lock are discussed. Other methods for reducing false lock accidents are also discussed, including safety devices and specific training and instruction topics and techniques.
On a New Passive Scalar Equation With Variable Mass Diffusivity
Authors: Gori Fabio , Boghi Andrea
Published: August 2009

The present work investigates the mass conservation equation of a Newtonian and non-Newtonian fluid in turbulent flow with variable mass diffusivity. The mass conservation equation is considered with the fluctuating terms in the concentration as well as in the mass diffusivity and is written for the average concentration, for the fluctuating concentration one as well as for the square of the fluctuating concentration. A new term appears in the form of product of the fluctuating mass diffusivity to the space gradient of the concentration fluctuation. This new term is interpreted and introduced in the mass conservation equation of the square of the fluctuating concentration where other new terms are also appearing. A possible physical interpretation is given to the different terms. Assuming several relations between mass diffusivity and concentration it is then possible to write expressions for the average and the fluctuating mass concentration which can be simplified on the basis of physical and mathematical considerations. Specifically, the mass flux is then expressed as the product of the derivative of the mass diffusivity to the gradient of the square of the mass fluctuation. Further considerations make possible to write a new mass conservation equation of the average concentration which include a new term which takes into account the space gradient of the mass flux. The mass conservation equation can be solved with the coupled solution of the equation of the square of the concentration fluctuation.
Investigation Into the Crossflow Microfiltration Process Utilizing Ceramic Membrane Applied to Bacteria Reduction and Clarifying of Ac¸ai Juice
Authors: Haneda Renata Natsumi , Fontes Se´rgio Rodriques
Published: August 2009

This paper reports the results of the crossflow microfiltration process applied to the reduction of bacteria and retention of particles in suspension of ac¸ai (Euterpe oleracea Mart.) juice. A commercial membrane of α-alumina (Al2O3) in the form of a tube with 1.2μm of average pore size was utilized to investigate the reduction of the bacteria of ac¸ai juice without using high temperatures (pasteurization). This pore size of the ceramic structure was utilized in an attempt to reduce the polarization phenomenon and improve the permeate flux without utilizing the usual enzymatic treatment made in the microfiltration processes that utilize polymeric membrane (Cianci et al., 2005 and Ushikubo et al., 2006). An anthocyanin concentration was also observed during the microfiltration process followed by suspended particles retention as an indicator of ac¸ai juice clarifying. The Scanning Electronic Microscopy (SEM) was utilized as an essential tool to characterize the morphology of the ceramic micro porous structure and to evaluate the formation of a polarization layer on the membrane surface, while the Optical Microscopy was used to analyze the difference in the characteristics between samples of concentrate and permeate.
Mulit-Pulse Orbits and Chaotic Motion of Composite Laminated Plates
Authors: Guo Xiangying , Zhang Wei , Yao Ming-Hui
Published: August 2009

This paper presents an analysis on the nonlinear dynamics and multi-pulse chaotic motions of a simply-supported symmetric cross-ply composite laminated rectangular thin plate with the parametric and forcing excitations. Firstly, based on the Reddy’s three-order shear deformation plate theory and the model of the von Karman type geometric nonlinearity, the nonlinear governing partial differential equations of motion for the composite laminated rectangular thin plate are derived by using the Hamilton’s principle. Then, using the second-order Galerkin discretization approach, the partial differential governing equations of motion are transformed to nonlinear ordinary differential equations. The case of the primary parametric resonance and 1:1 internal resonance is considered. Four-dimensional averaged equation is obtained by using the method of multiple scales. From the averaged equation obtained here, the theory of normal form is used to give the explicit expressions of normal form. Based on normal form, the energy phase method is utilized to analyze the global bifurcations and multi-pulse chaotic dynamics of the composite laminated rectangular thin plate. The results obtained above illustrate the existence of the chaos for the Smale horseshoe sense in a parametrical and forcing excited composite laminated thin plate. The chaotic motions of the composite laminated rectangular thin plate are also found by using numerical simulation. The results of numerical simulation also indicate that there exist different shapes of the multi-pulse chaotic motions for the composite laminated rectangular thin plate.
Kinematic Calibration of the Hexaglide Parallel Robot Using a Simple Measurement System
Authors: Abtahi Mansour , Pendar Hodjat , Alasty Aria , Vossoughi Gholamreza
Published: August 2009

Because of errors in the geometric parameters of the parallel robots, it is necessary to calibrate them to improve the positioning accuracy for accurate task performance. Traditionally, to perform system calibration, one needs to measure a number of robot poses using an external measuring device. However, this process is often time-consuming, expensive and difficult for robot on-line calibration. In this paper, a methodical way of self-calibrating of Hexaglide parallel robot is introduced. This method is performable only by measuring input joint variables and errors of positioning relative to the desired position in some sets of configurations where in each set the desired position is fixed, but orientations of the moving platform are different. In this method, measurements are relative, so it is performable by using a simple measurement device. Simulations give us an idea about the number of desired points, the number of orientations in each point and the effect of noise on the calibration accuracy.
A Flow Visualization Study of the Jet Dynamics in a Round Jet Impinging on a Foamed Aluminum Porous Media
Authors: Yakkatelli Ravi , Wu Qianhong , Fleischer Amy
Published: August 2009

The use of foamed metals for highly effective heat sink design is increasing, but little has been done to quantify the fluid dynamics of impinging round jets on porous media. An understanding of the fluid dynamics is crucial to optimize the eventual heat transfer performance. In this study, smoke-wire flow visualization is employed to investigate the behavior of a round jet issuing from a straight tube and impinging on foamed aluminum porous media used as a heat sink. The porosity of the foamed aluminum porous media is varied and the effect on the flow dynamics of the impinging jet is examined. The effects of jet-to-surface spacing and Reynolds number are explored for unheated porous media.
Intention Tremor in Multiple Sclerosis: Measuring and Modelling Arm Dynamics and Elbow Torque
Authors: Ketteringham Laurence P. , Neild Simon A. , Hyde Rick A. , Jones Rosie J. S. , Davies Smith Angela
Published: August 2009

This paper reports on a project to measure and control tremor in individuals with multiple sclerosis (MS). It discusses systems for measuring and modelling upper limb movements and intention tremor, together with initial movement measurement and torque modelling data. The system uses microelectromechanical systems (MEMS) sensors to measure movements of the upper limb representative of everyday tasks. Surface electromyogram (EMG) measurements are taken simultaneously to provide gross muscle activity data. A dynamic model is used to simulate the movements, allowing particular sites to be studied in detail. Initial movement data is presented, comparing analysed EMG data and torque estimated by the dynamic model around the elbow joint. Despite the simple analysis, a good fit was obtained. The dynamic model includes a neuromuscular modelling system which will be used in future work to simulate the interactions between measured movements containing intention tremor and the intention behind them, allowing better understanding of the tremor and creating better descriptions of the tremor. Future work will use measured data and modelling to develop methods of attenuating intention tremor, by providing real-time feedback control of tremor reduction devices, without adversely affecting the underlying intended movement.
Machinability Studies and Artificial Neural Network Modeling of Turning Al-SiC (10p) Metal Matrix Composites
Authors: Muthukrishnan N.
Published: August 2009

The paper presents the results of an experimental investigation on the machinability of fabricated Aluminum metal matrix composite (A356/SiC/10p) during continuous turning of composite rods using medium grade Polycrystalline Diamond (PCD 1500) inserts. MMC’s are very difficult to machine and PCD tools are considered by far, the best choice for the machining of these materials. Experiments were conducted at LMW-CNC-LAL-2 production lathe using PCD 1500 grade insert at various cutting conditions and parameters such as surface roughness, specific power consumed, and tool wear were measured. Machining was continued till the flank wears land on the tool crossed 0.4 mm. The influences of cutting speed on the insert wear and built-up edges (BUEs) formation were studied. The present results reaffirm the suitability of PCD for machining MMCs. Though BUE formation was observed at low cutting speeds, at high cutting speeds very good surface finish and low specific power consumption could be achieved. An Artificial Neural Network (ANN) model has been developed for prediction of machinability parameters of MMC using feed forward back propagation algorithm. The various stages in the development of ANN models VIZ. selection of network type, input and output of the network, arriving at a suitable network configuration, training of the network, validation of the resulting network has been taken up. A 2-9-3 feed forward neural network has been successfully trained and validated to act as a model for predicting the machining parameters of Al-SiC (10p) -MMC. The ANN models after successful training are able to predict the surface quality; specific power consumption and tool wear for a given set of input values of cutting speed and machining time.
Kinematics and Singularity Analysis of the Hexaglide Parallel Robot
Authors: Abtahi Mansour , Pendar Hodjat , Alasty Aria , Vossoughi Gholamreza
Published: August 2009

In the past few years, parallel manipulators have become increasingly popular in industry, especially, in the field of machine tools. Hexaglide is a 6 DOF parallel manipulator that can be used as a high speed milling machine. In this paper, the kinematics and singularity of Hexaglide parallel manipulator are studied systematically. At first, this robot has been modeled and its inverse and forward kinematic problems have been solved. Then, formulas for solving inverse velocity are derived and Jacobian matrix is obtained. After that, three different types of singularity for this type of robot have been investigated. Finally a numerical example is presented.
Energy Savings Potential by Substituting Driving With Walking and Cycling for Short Distance
Authors: Mahlia T. M. I. , Husnawan M. , Masjuki H. H. , Remuslara L. , Saidur R.
Published: August 2009

Vehicles energy consumption produces several emissions such as carbon dioxide (CO2), nitrogen oxide (NOx) and noise. This paper attempts to evaluate potential reduction in oil consumption and CO2 emissions if the obese and overweight conditions were eliminated from the adult population through the use of walking or cycling for transportation, and if individuals between the ages of 10 and 64 adopted recommended levels of daily exercise by walking or cycling instead of driving. Substantial co-benefits accompany widespread adoption of physical activity. The results found that the reductions in emissions from substituting driving with walking and cycling are significant enough to show a possible improvement of air quality. The highest reduction of CO2 emissions comes from the substitution of driving with exercising by cycling for 7 hours a week, which amounts to 2.38 Tg (Teragram) of reduction.
Portable Photonics Optical Detection System for Monitoring Molecular Oxygen and Photosensitizer Concentration in Photodynamic Therapy Milieu
Authors: Premasiri A. , Happawana G. , Rosen A.
Published: August 2009

Photodynamic therapy (PDT) is an FDA approved, effective, and minimally invasive cancer treatment modality with few side effects. Optimization of the PDT protocol for individual patient requires good therapeutic selectivity and high efficacy. This is possible only by enabling continuous monitoring of treating area of each patient for essential components for PDT. Two most essential components of PDT are photosensitizing agents and molecular oxygen. Currently the PDT is rather a blind process since there are no proper methods to monitor the tumor blood oxygen level and photosensitizer concentration during the treatment. In this paper we present an optical technique to monitor the tumor oxygen level and photosensitizer concentration. The technique investigated in this paper is a reflection optical technique designed with tiny semiconductor lasers and a silicon photodiode. The measurement of blood oxygen level with optical technique is not an uncommon method, but conventional transmission technique cannot be applied to the internal organs such as esophagus, trachea, and intestine. The light used in the monitoring system comes from three semiconductor diode lasers of 630nm, 650 nm and 940 nm wavelengths. Three lasers and the photodiode are mounted on to a small package to be able to imprint on to the balloon catheter that the PDT light delivery system is carrying in case of body cavities. Lasers and the photodiode are powered and controlled by the control box that is connected with a tinny cable. Light sources and respective photodiode output is controlled by the LabVIEW virtual instrumentation. The sequential on and off of light source and respective reflective signal is processed with MATLAB code integrates in the LabVIEW to make automatic calculation of the corresponding light absorption by each chromophore and to show the change in oxygen level and the photosensitizer concentration in the monitoring area. The designed system is capable of monitoring change in oxygen and photosensitizer level in any part of the human body where the tinny package is possible to place.
Glass Ceramics for High-Resolution Imaging
Authors: Johnson J. A. , Weber R. , Kolesnikov A. I. , Schweizer S.
Published: August 2009

Glass-ceramic materials are being developed for use in digital mammography systems. The materials are transparent x-ray storage phosphors, which are potentially less expensive than competing materials with superior performance. The materials do not suffer from loss of resolution and increased noise due to light scattering from grain boundaries, as do the currently available polycrystalline materials. The glass ceramics are based on Eu2+-doped fluorochlorozirconate glasses. These can be heat treated to nucleate Eu-doped barium chloride nanocrystals. The glass ceramic converts ionizing radiation (typically x-rays) into stable electron-hole pairs that can be “read” by scanning a stimulating light beam across the glass to cause photostimulated luminescence (PSL) emission. Measurements on the materials are ongoing to elucidate structure-property relationships developed as a result of introducing rare-earth ions and modifying process conditions. Image quality measurements indicate that the current material competes with state-of-the-art x-ray imaging plates. The paper presents results on structure, properties and future directions of the materials described above.
Fuzzy Expert System Development for Electric Generator Failure Diagnostics
Authors: Xu Shuzhen , Susemihl Enrique
Published: August 2009

This paper presents the development of an expert system to help engineers assess the condition of turbine generators. The expert system is designed to minimize the search and input of data in order to address the issue of the limited time available to engineers compared to the large amount of information to be investigated. To imitate the imprecise reasoning process as well as the vague information and qualitative variables inherent in this type of evaluation, fuzzy logic is used. An example of application to one failure mode, i.e., loose stator bar, is also presented.
Electron-Phonon Non-Equilibrium in Nanoscale Gold Films
Authors: Pattamatta Arvind , Madnia Cyrus K.
Published: August 2009

Ultrashort-pulsed laser irradiation on metals creates a thermal non-equilibrium between electrons and the phonons. Previous computational studies used the two-temperature model and its variants to model this non-equilibrium. However, when the laser pulse duration is smaller than the relaxation time of the energy carriers or when the carriers mean free path is larger than the material dimension, these macroscopic models fail to capture the physics accurately. In this paper, the non-equilibrium between energy carriers is modeled via numerical solution of the Boltzmann Transport Model (BTM) for electrons and phonons which is applicable over a wide range of length and time scales. The BTM is solved using the Discontinuous Galerkin Finite Element Method for spatial discretization and the three-step Runge Kutta temporal discretization. Temperature dependant electron-phonon coupling factor and electron heat capacity are used due to the strong electron-phonon non-equilibrium considered in this study. The results from the proposed model is compared with existing experimental studies on laser heating of macroscale materials. The model is then used to study laser heating of gold films, by varying parameters such as the film thickness, laser fluence and pulse duration. It is found that the temporal evolution of electron and phonon temperatures in nanometer size gold films are very different from the macroscale films. For a given laser fluence and pulse duration, the peak electron temperature increases with a decrease in the thickness of the gold film. Both film size as well as laser fluence significantly affect the melting time. For a fluence of 5000 J/m2, and a pulse duration of 75 fs, gold films of thickness smaller than 200 nm melt before reaching electron-phonon equilibrium. However, for the film thickness of 2000 nm, even with the highest laser fluence examined, the electrons and phonons reach equilibrium and the gold film does not melt.
Problem Based Learning Initiative in Collaboration With the CT College of Technology’s Center for Life Support and Sustainable Living
Authors: Wosczyna-Birch Karen , Jaramillo Paola , Birch John , Adrezin Ronald
Published: August 2009

The Connecticut (CT) College of Technology with funding from the National Science Foundation (NSF) has established the Center for Life Support and Sustainable Living. The Center is the result of partnerships with the CT Community Colleges, four-year institutions, local hospitals and industry, and the collaboration with NASA through the CT Space Grant College Consortium. The primary goals of the Center are the following: (1) to provide teams of community colleges and four-year university students opportunities to apply science, engineering and technology knowledge as well as professional skills necessary to be successful in future employment to real-world problems that address life support and sustainable living issues; (2) to strengthen the 2+2+2 pathways between community colleges and four-year institutions; (3) provide professional development opportunities for community college faculty; (4) implement strategies to recruit and retain a diverse population of students interested in STEM disciplines; and (5) develop multi-media curriculum modules using contextual or problem-based-case-based learning (PBCL). The project has instituted interdisciplinary teams of community college and university students who are initiated into the program with intensive instruction and project planning and management, leadership, teamwork, and behavioral diversity using DISC behavioral analysis profiles during an intense three-week period during the winter intersession. In addition to the initial training, student participants must commit to working approximately 250 hours during their school year for which they are working on their respective team-based projects. As part of their hours, they must meet as a full team a minimum of twice each month. Participating students are currently mentored by two and four-year faculty and industry representatives. So far, the research has been conducted during the summer months and the academic year on life support and sustainable living projects for NASA, the U.S. Coast Guard, medical facilities, such as the CT’s Children’s Medical Center, and industry partners such as Hamilton Sundstrand and Kaman Aerospace. As a result of these research projects, the community college and four-year faculty are implementing real-world life support and sustainable living projects and collaboratively are writing multi-media Project-Based-Case Based Learning modules, which incorporate technology and science skill standards. The Problem-Based-Case-Based multi-media modules are being piloted at the CT College of Technology’s community colleges and universities.
Effective Simulation of Ballscrew Drives Modeled Using Finite Element Methods
Authors: Okwudire Chinedum E. , Altintas Yusuf
Published: August 2009

This paper presents a realistic and fast method of simulating ballscrew drives, taking into account the position-dependent changes in dynamics as the nut moves along the ballscrew. It achieves this by first using a strategy whereby the motion of the nut along the ballscrew is accurately and smoothly captured in simulations using the shape function of the finite element model as an interpolating function. Secondly, it applies a method based on Component Mode Synthesis with Modal Acceleration Recovery to achieve a full reduction of the ballscrew while still allowing the nut to move from node to node on the ballscrew. As a result the computational efficiency of the model is improved significantly without any considerable sacrifice of its accuracy.
Signal Recovery Based on Bistable Stochastic Resonance
Authors: Leng Yong-gang , Guo Yan , Zhang Ying
Published: August 2009

This paper deals with the problem of the waveform distortion in the output of a bistable stochastic resonance system. The waveform recovery formula is proposed by observing the movement track of a particle in the bistable system and the suggested recovery system. The recovery mechanism and rules with and without noise are revealed. Moreover, a novel explanation about pulse distortion caused by the particle’s transitions occurring at the wells’ inflexions is put forward. Under the stochastic influence of the noise in subthreshold stochastic resonance, we develop a method via cascaded-bistable stochastic resonance and the recovery system with tuned system parameters to restore the output waveform. The numerical simulation has presented that it can recover the waveform containing weak information submerged in noise effectively. The method is applicable to both periodic and aperiodic signals.
Application of a New Cylindrical Element Formulation in Finite Element Structural Analysis of FGM Hollow Cylinders
Authors: Ahmadian M. T. , Taghvaeipour A. , Bonakdar M.
Published: August 2009

Functionally graded materials are advanced composite materials consisting two or more material ingredients that are engineered to have a continuous spatial variation of properties. There are a few analytical methods available to solve the governing equations of FGM made structures, confined to some specific and limited shapes, loadings and boundary conditions. Hence the numerical methods such as FEM are used to treat these materials. In previous studies the finite element method was used to solve thin walled FG structures like shells and plates by modification of the conventional shell and plate elements. Solving the thick walled FG structures confronts some difficulties. One of the methods to overcome this problem is laminating the structure across the direction of material variation, assuming constant material properties in each layer. When the thickness is increased, the number of layers representing the FGM should be also increased to produce an accurate result. Increasing the number of elements implies great time consumption and required memory space. One of the most commonly shapes present in FG structures are hollow cylinders whose analysis is so complicated that may not be done by conventional elements. In this study a superelement approach is chosen to confront the problem. Design and application of superelements in efficient prediction of the structural behavior in a short time has been one of the research interests in the last decade. The superelements are designed for special problems so that they could substitute a huge number of conventional elements in modeling and analysis. In this study a new cylindrical superelement is incorporated to model the functionally graded cylinders, and modal analysis is performed. The advantage of this cylindrical superelement lies in the fact that no lamination is needed, anymore and only a few superelements can predict the vibration behavior of FG cylinders accurately. Several examples are solved based on the new element formulation and the natural frequencies and mode shapes are obtained. Comparison of the findings with the conventional elements reveals time saving and accuracy of the results.
About a New Conception of Internal Combustion Engine Construction: I—Rotary Engines
Authors: Oledzki Wieslaw J.
Published: August 2009

In the paper I present a new construction of positive displacement internal combustion engines (US patent application 12/218,959, PL patent application PL 385 728). The construction is based on some newly invented mechanisms, the most compact and robust ones in existence, and is particularly suitable for coping with high loads. The construction is intended for high power density Diesel engines (particularly special purpose, e.g. military ones), homogeneous charge compression ignition and detonation engines. The presented conception promises substantial improvement of such important engine parameters as swept volume/total volume, power/total volume and power/weight ratio, without increasing specific loads and thus without sacrificing engine’s strength and reliability. Moreover, there exists a large variety of engine’s configurations within the proposed conception, namely oscillating engines and rotary engines utilizing flat or spatial mechanisms that can be combined with considerable variety of scavenging systems, ignition systems etc. Engines of the proposed structure (including rotary ones) have sealing almost as simple, tight and reliable as conventional ones and much simpler, tighter and much more reliable than conventional (Wankel) rotary engines. Besides the exceptional strength and compactness, the most outstanding features of the engines according to the presented invention are their gas turbines-like qualities. For example, rotary engine of the presented invention can produce 6 power strokes per shaft revolution (thus displaying V12 engine smoothness) while having only 3 major moving parts of extraordinarily strong structure. Moreover, the engine scavenging system makes the gas flow almost as smooth as (and similar to) that to be found in gas turbines. The first part of the paper concerns exclusively rotary engines and discussion of oscillating ones is postponed to the second part. The paper also touches upon the method for balancing the proposed rotary engines as well as an analogous problem of balancing my oscillating engines presented in the second part of the paper.
A New Design of Tooth Profiles Increases Synchronous Belt’s Fatigue Life
Authors: Guo Jianhua , Jiang Hongyuan , Han Gang , Yan Hui
Published: August 2009

Synchronous belt and its driving pulley have non-conjugate tooth profiles. Because of non-conjugate motion and polygon effect, interference occurs during incomplete meshing, resulting in excessive wear and tear at tooth-root, which are the main forms of failure of synchronous belts. Tooth cracking also results from uneven stress distribution and/or increased maximal stress. In addition to discovering better materials to increase the strength of the belt’s teeth, optimization of the geometry of tooth profiles of belt and pulley to decrease the maximum tooth-root stress and to reduce interference during meshing is critical in improving the carrying capacity and increasing the belt’s life span. In the present study we proposed a new design of synchronous belt’s and pulley’s tooth profiles, modifying several key geometric parameters commonly used in synchronous belts’ designs. Applying the conformal mapping function and the theory of plane elasticity we systemically investigated the distribution of stress and distortion at the belt’s and pulley’s teeth of varying geometric parameters and analyzed the interference during meshing using an approach to investigating tooth profiles of non-constant pitch diameter. Finite Element Analysis showed that with the same load the maximum principal stress values of belt teeth in complete meshing in our design (STSB) were 54.4% and 67.8% of that of HTD (by Uniroyal) and STPD (by Good Year) belts with an 8 mm pitch commonly used in automobiles, respectively. The uneven distribution of stress along the edge of tooth profile was reduced, and the interference during meshing minimized with our design. We then experimentally tested belts made of the same materials with the three designs manufactured by the same factory. The belts were tested in the enclosed type of testing machine for synchronous belt’s fatigue-life, power = 6.5 kW and speed = 1500 r/min with test belt tension at 400 N. The fatigue lives of the belts (n = 5 each group) were 988 ± 36, 439 ± 21 and 665 ± 22 hours (mean ± SD) for STSB, HTD and STPD belts (p<0.0001), respectively, demonstrating the superiority of our design. We anticipate that the new design will have wide applications not limited to the automobile industry.
Deterministic Risk Methodology for Road Tunnels
Authors: Vidmar Peter , Petelin Stojan
Published: August 2009

The definition of the deterministic approach in safety analyses arises from the need to understand the conditions that emerge during a fire accident in a road tunnel. The key factor of the tunnel operations during the fire is the ventilation, which during the initial phases of the fire have a strong impact on the evacuation of people and later on the access of the intervention units in the tunnel. The paper presents the use of the CFD model in the tunnel safety assessment process. The set-up of the initial and boundary conditions and the requirement for grid density found from validation tests of an FDS (Fire Dynamics Simulator) is used to prepare three kinds of fire scenarios, 20MW, 50MW and 100MW, with different ventilation conditions; natural, semi transverse, transverse and longitudinal ventilation. The observed variables, soot density and temperature, are presented in minutes time steps through the entire tunnel length. Comparing the obtained data in a table allows the analyses of the ventilation conditions for different heat releases from fires. The second step is to add additional criteria of human behaviour inside the tunnel (evacuation) and human resistance to the elevated gas concentrations and temperature. What comes out is a fully deterministic risk matrix that is based on the calculated data where the risk is ranged on five levels, from the lowest to a very dangerous level. The deterministic risk matrix represents the alternative to a probabilistic safety assessment methodology, wherein the fire risk is represented in detail and the CFD (Computational Fluid Dynamics) model results are physically correct.
Added Viscoelastic Wheel Dampers for Reducing Railway Noise
Authors: Wang Z. , Chen Z. B. , Li M. Z.
Published: August 2009

Mechanisms associated with interaction of the wheel and the rail in the vertical and horizontal direction are investigated. The noise-generating characteristics and the calculation model of wheels are studied theoretically. An improved railway wheel added with viscoelastic constrained damping layers has been researched out theoretically and experimentally. Design equations and graphs are developed for the geometrical parameter of viscoelastic constrained damping layers used in wheels. Using existing theory, the procedures are developed for predicting the structure loss factor of structural composites with different numbers of constrained damping layers. The structure loss factor of wheels attached with symmetrical three constrained layers is optimally calculated using MATLAB. A number of experiments with pulse excitations in the laboratory are carried out from the number of constrained damping layers, the material of constrained layers, as well as the position added to the wheel. From the experiments, steel is chosen as the material of constrained layer, and rubber with high loss factor and wide temperature range is chosen as the material of elastic layer. Both materials are experimentally measured. The theoretical predictions of the noise reduction effect is compared with the experimental measurements. The results shown that the wheel noise is obviously reduced.
Differential-Delay Equation Model of Gene Expression: A Continuum Approach
Authors: Verdugo Anael , Rand Richard H.
Published: August 2009

This paper presents an analytical study of the stability of the steady state solutions of a gene regulatory network with time delay. The system is modeled as a continuous network and takes the form of a nonlinear delay differential-integral equation coupled to an ordinary differential equation. Two examples are given in which the critical delay causing instability is computed.
Effect of Hot Solder Dipping on Part Stresses
Authors: Meschter Stephan , McKeown Stephen
Published: August 2009

Hot solder dipping is an accepted method to mitigate whisker growth on electronic components plated with pure tin. To provide the best protection from tin whiskers, the solder coating needs to be up to the package body. The conventional wisdom for solder dipping maintains that dipping up to the package body can cause component damage. If the specific construction differences of ceramic and plastic-encapsulated parts are considered, it appears that while temperature gradients are important for ceramic parts, temperature is the major factor in failure of plastic parts. Finite-element analysis (FEA) is used to determine internal stresses resulting from solder dipping. Transient thermal FEA analysis is used to determine the temperature distribution inside the part and a static structural FEA is used to calculate internal stresses. For a 128-lead plastic part, maximum stresses from dipping the side of the package are 35% of those expected in reflow and 37% higher than that expected if only the lead tip is dipped. For a 184-lead ceramic part, dipping until the package side touches the solder increases stresses by a factor of more than three over dipping the lead to within 10-mils (0.25 mm) from the package body. Plotting the maximum relative stress as a function of maximum semiconductor die temperature shows a strong linear correlation between maximum temperature and stress for plastic — a correlation not observed for a ceramic part.