bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Mechanistic Approach for Micro End Milling Force Modeling
Authors: Jun Martin B. G. , Goo Chanseo , Malekian Mohammad , Park Simon S.
Published: May 2012

This paper investigates the mechanistic modeling of micro end milling forces, with consideration of the effects of plowing, elastic recovery, effective rake angle, and flank face rubbing. Two different mechanistic models are developed for shearing- and plowing-dominant regimes. Micro end milling experiments are conducted to validate the model for Aluminum 6061; and, the model appropriately predicts force profiles for a wide range of feed rates, and prediction of the root mean square (RMS) values of the resultant forces is, on average, within a 12% error. The study of the model shows that plowing and rubbing force contributions are significant, especially at low feed rates. The edge radius is found to have a significant effect on plowing and rubbing force components and the effective rake angle, which indicates that it is important to maintain a low edge radius to reduce micro end milling forces.
Glass Cover Temperature and Upward Heat Losses of a Single Glazed Collector With Nearly Vertical Configuration
Authors: Kumar Suresh , Mullick Subhash C.
Published: May 2012

Estimation of upward heat losses is required for design or thermal performance evaluation of a flat plate collector. Collectors with vertical configuration are used at high latitudes and are integrated with building walls. Values of glass cover temperature are required for calculation of upward heat losses under different operating conditions. Glass cover temperature can be determined from numerical solution of heat balance equations. In the present work an empirical relation for glass cover temperature of a single glazed flat plate collector for angle of tilt 60 to 90 degree is proposed. Values of glass cover temperature obtained from this empirical relation have been used for computation of top heat loss coefficient of flat plate collector. Analytical equation has been employed for estimation of Ut. The range of variables covered in the present analysis is 20 °C to 150 °C for absorber plate temperature, 0.1 to 0.95 for absorber coating emittance, 20 mm to 50 mm for air gap spacing, 60 deg to 90 deg for collector tilt, 5 W/m2K to 30 W/m2K for wind heat transfer coefficient and −10 °C to + 40 °C for ambient temperature. The maximum absolute error in values of Ut is within two percent in comparison to values obtained by numerical solution of heat balance equations over the entire range of variables covered in the present work.
The Effect of Using Different Based Nanofluids on Trapezoidal Microchannels Cooling Performance
Authors: Gunnasegaran P. , Mohammed H. A. , Shuaib N. H.
Published: May 2012

Numerical investigations are performed to explore the aluminum trapezoidal microchannel heat sink (MCHS) cooling benefits by using different types of base nanofluids for laminar flow. Considering a diamond nanoparticle with particle volume fraction of 2% was mixed in four different base fluids including water, ethylene glycol (EG), oil, and glycerin. The three-dimensional steady, laminar flow and heat transfer governing equations are solved using the finite volume method. The computational domain is taken as the entire heat sink including the inlet/outlet ports, wall plenums, and microchannels. The impact of different types of base fluids in these four mixture flows on the microchannel temperature profiles, heat transfer coefficients, pressure gradients, friction factor, and thermal resistance were examined. It is found that the best uniformities in heat transfer coefficient and temperature among the four mixture flows for diamond nanoparticle can be obtained in MCHS using glycerin-base nanofluid followed by engine oil-base nanofluid, EG-base nanofluid, and water-base nanofluid. It is found that, the use of high-Prandtl number base fluid such as glycerin is preferable and can be recommended to maximize the merits of adding nanoparticles for MCHS performance.
Rheological Behavior and Microstructure of Flame Retardant Polypropylene Composites
Authors: Jiang Guo , Liao Kai , Han Juan-Juan , Feng De-Xian , Huang Han-Xiong
Published: May 2012

Polypropylene (PP)/magnesium hydroxide (MDH) composite was melt-mixed using a twin-screw extruder. Two types of MDH were used, one with the modification of silane and another without. The rheological behavior was measured by capillary and dynamical rheometer. Microstructure of these composites was observed by SEM. Their flame retardancy was characterized by oxygen index and Horizontal/Vertical burning test. Results showed that shear viscosity and complex viscosity of PP with modified MDH were lower than that of PP with non-modified MDH. SEM results also showed a better dispersion of silane modified MDH in PP matrix. With the increase of MDH content, the oxygen index of composites was increased. When the content was increased to 60 wt%, the composite was UL94 HB and V-1.
Design and Simulation of Injection Mold for the Shell of Switch
Authors: Wang Chuanyang , Hu Shuai , Qian Qiubo , Shen Xuanxuan
Published: May 2012

The 3D models of gating system, ejection mechanisms and cooling system of the swtich shell for injection mold are designed by using Pro/ENGINEER software. MOLDFLOW is utilized for CAE analysis. Three schemes are obtained by changing the gate location during the injection molding process. After comparing the volume shrinkage during injection, shrink marks index, filling time and the injection pressure, the best scheme is obtained. According to the optimal scheme, the injection mold is designed. The results showed that simulation analysis method can not only improve the successful probability of mold trial, but also shorten the production development cycle of developing product.
Application of Robust H∞ Technique to Control Water Level of Boiler Drum in the Presence of Parametric Uncertainties
Authors: Moradi Hamed , Saffar-Avval Majid , Bakhtiari-Nejad Firooz
Published: May 2012

Poor control of drum water level is one the reasons for emergency shutdowns in power plants. To overcome uncertain disturbances affecting water level of drum, a robust controller must be designed. In this paper, a linear time invariant (LTI) model of the boiler system associated with parametric uncertainties is considered. The input variables are feed-water and steam mass rates while the output variable is drum water level. Parametric uncertainties are modeled in the frequency domain as a disc type template. General control configuration is presented to model the uncertain system with unstructured uncertainty in the form of multiplicative input uncertainty. Only nominal performance is achieved for perturbed plants using μ-analysis with applying an inversed-base controller. However, since the robust stability and performance are not satisfied, desired responses can not be obtained. To overcome this problem, an optimal robust controller is designed based on μ-synthesis with DK-iteration algorithm which satisfies the constraints of control signals too.
In-Situ Damage Evaluation Using Ball Indentation Test Method
Authors: Prakash Raghu V.
Published: May 2012

Automated ball indentation is a semi-invasive test method that is gaining importance as a field test method in the recent times. Based on the few cycles of loading and unloading, and corresponding load, deflection characteristics, it is possible to estimate the true stress-true strain information of a material. In the present work, ball indentation has been used to evaluate the static and fatigue properties of base material as well as material subjected to different types of damage, such as fatigue, weldment etc. The tensile properties and fatigue properties were found to be affected by the prior damage history.
The Effects of Using Formaldehyde as an Additive on the Performance of an HCCI Engine Fueled With Natural Gas
Authors: Jahanian Omid , Jazayeri Seyed Ali
Published: May 2012

In this paper, the performance of a natural gas HCCI engine is studied through a thermodynamic model including detailed chemical kinetics. Then the influence of using formaldehyde as an additive on the engine characteristics has been investigated. Results show that it is possible to change engine working limits using this additive. Furthermore, there is an optimum additive content for each operating condition which leads to higher output work and power. It is also shown that the air/fuel mixture will ignite earlier using this additive so it is conceivable to reduce inlet mixture temperature resulting in better performance due to higher volumetric efficiency.
Applying Particle/Grid Hybrid Method to Fuel Spray With Collision Jet for Automobile Engines
Authors: Ishii Eiji , Ishikawa Masanori , Sukegawa Yoshihiro , Yamada Hiroshi
Published: May 2012

A fuel spray contains multi-scale free surfaces: liquid films formed at the fuel-injector outlet, ligaments generated by the liquid-film breakup, and droplets generated from the ligaments within the air/fuel mixture region. To simulate multi-scale free surfaces, we previously developed a fuel spray simulation combining the liquid-film breakup with the air/fuel mixture. In this study, we modified a part of the liquid-film breakup simulation that uses a particle/grid hybrid method. The procedures combining a particle method and a grid method were changed to obtain more accurate prediction. First, a simple benchmark test, collapse of a water column as investigated by Martine and Moyce, was used to verify the modified simulation method; the behavior of the water column better agreed with measurements than that by the original method. Next, we applied the modified method to simulate the collision jets from three kinds of nozzles. The simulation results were verified by comparison with measurements; the predicted liquid-film breakup qualitatively agreed well with measurements. Furthermore, the errors of mean droplet-diameters between the simulations and the measurements were less than 12%. Therefore, we found that the modified method was effective for spray simulation.
An Investigation of Enterprise Resource Planning Implementation: Empirical Evidence From Indian Companies
Authors: Kale Pramod T. , Banwait Sukhwant S.
Published: May 2012

Due to globalization, there is tremendous demand on Indian companies to lower costs, enlarge product assortment, improve product quality, and provide reliable delivery dates through effective and efficient coordination of production and distribution activities. To achieve these conflicting goals, companies must constantly re-engineer or change their business practices and employ information systems like Enterprise Resource Planning (ERP). However, implementing ERP system is a difficult and high cost proposition. There are mixed results of success and failure in different companies. With a survey of manufacturing companies in India and subsequent detailed case study in one ERP implemented company, this study analyzes various parameters of ERP implementations with factor analysis and logit regression analysis. It is revealed that with clear goals of ERP implementation and proper ERP software selection, the companies are benefited in reducing inventory, improving customer service and other intangible benefits. The top management support, strong and meaningful training program are found the enabling factors of its success. It is argued that this study and ERP implementation model proposed in this paper is valuable to researchers and practitioners interested in implementing ERP system. The findings will also be helpful in extracting the better results from ERP implementation.
Polyline Closure Law Design and Realization in Long-Distance Water-Supply Project
Authors: Zhang Jian , Yu Xiaodong , An Jianfeng , Hazrati Arash
Published: May 2012

Long-distance water-supply project is an effective way to solve the uneven spatial and temporal distribution of water resources, but the safety of water conveyance system is threatened seriously by water-hammer. Based on the research of the characteristic of water-hammer with pipe friction considered, the formula of indirect water-hammer is deduced and the application scope of the formula is also discussed, which is the theoretical basis for the design of polyline closure law. To the defects that valve closure time is long and response of accident is slow in the long-distance water-supply project, polyline closure law is designed with consideration of valve overflowing property, which greatly reduces the closure time and water-hammer. At the same time, the flow inertia is large in long-distance water-supply project and break point of polyline closure law is hard to fix. In order to improve the reliability of the mechanical operating system, locking device is installed, which make the polyline closure law carry out successfully and provide a new idea for water hammer protection in long-distance water-supply project.
Effect of Inclination on Slug Flow Characteristics
Authors: AbdulKareem Lokman A. , Sharaf S. , Azzopardi Barry J. , Hunt Andrew
Published: May 2012

Modern oil/gas well drilling methods in particular in the offshore industry involve deviated drilling in which the production tubing can be inclined at any angle between the vertical and the horizontal. Riser tubes from the seabed to the surface or to floating production vessels (FPSO) will also rarely be exactly vertical. This work describes a study carried out at the University Of Nottingham on the effects of inclination on gas / liquid slug flow. Two advanced tomography techniques were applied simultaneously to the flow of a mixture of air and silicone oil in a 67 mm internal diameter pipe and the pipe was inclined at various angles. A twin plane Electrical Capacitance Tomography (ECT) electrode system driven by Tomoflow electronics was positioned below a Capacitance Wire Mesh Sensor (WMS) developed at Forschungszentrum Rossendorf-Dresden/Germany M. J. Da Silva et al [2]. This enabled an examination of the flow to be carried out at several levels of complexity. Both measuring sensors provide time and cross-sectionally resolved information about the spatial distribution of the phases. Conditions studied were superficial velocities for air ranged from 0.05 to 5.5 m/s and for silicone oil ranged from 0.0 m/s to 0.5 m/s. In present paper, the effect of inclination on the phase distribution in two phase gas liquid slug flow is presented. The liquid hold up within the slug region and in the elongated bubble zone and the averaged liquid hold up were calculated from the output data of the two measurements techniques. Radial gas volume fraction profiles and bubble size distributions were also processed from the wire-mesh sensor data. The shapes of the large bubbles and waves were compared for different inclination angles. The results indicate that the pipe inclination has a significant effect on the slug flow characteristics. Both Taylor bubble and small bubbles in the slug region tend to flow along the upper pipe wall and causing significant variation of Taylor bubble rise velocity with inclination angle.
Bifurcation Control for a S.D.O.F. Nonlinear System to a Principal Parametric Resonance With Time Delay
Authors: Qian Changzhao , Chen Changping , Dai Liming
Published: May 2012

The bifurcation and response of one-degree-of-freedom system with quadratic and cubic non-linearities to a principal parametric is investigated. Using time delay damp, the bifurcation is controlled. The method of multiple scales is used to determine the equations that describe to second order the modulation of the amplitude and phase with time about one of foci. These equations are used to determine the fixed points and their stability. Because there are some items which are time delay’s function in the bifurcation equations, changing the time delay parameters may change the bifurcation form or bifurcation point. Using numerical method, saddle-node bifurcation and transcritical bifurcation control are investigated. The result indicates that time delay controller can effectively control to this kind system.
Considerations About Human Factors in Risk Analysis for Ships With Alarm System
Authors: Barbarini Luiz Henrique Maiorino , de Andrade Bernardo Luis Rodrigues
Published: May 2012

In complex systems, such as vessels and commercial ships, the ability to understand and influence human behavior is essential to ensure safety and reliability. According to statistics of classification societies (Rothblum, 2000; ALERT!, 2003), humans are largely responsible for accidents on board and, therefore, are considered a major component of the dependability of vessels. This paper presents a proposal on how to address the human and organizational factors in risk analysis for ships, focusing on the scenarios where the crew interacts with the alarm and monitoring system. In order to illustrate the steps and assumptions to be done by an analyst applying the proposed model, the accident of the vessel Maersk Doha occurred in October of 2006 in the United States, is analyzed. The report on the investigation of this accident is public and accessible via the Internet site of the Marine Accident Investigation Branch – MAIB. This approach has the intention to be a proactive tool to anticipate and prevent accidents on board by means of the correct design and use of the ship’s alarm system.
Mathematical Modeling of Water-Gas Interfacial Motions in a Straight Flow Channel of PEMFCs
Authors: Yang Yuelei , Zhang Dan
Published: May 2012

Polymer Electrolyte Membrane Fuel Cell (PEMFC) has been recognized as one of most promising technologies for automotive and stationary power generations. In this paper, a mathematical model was developed to analyze the water motions in the flow channels of PEMFCs. The two phase gas/liquid flow was simulated with different gas velocities, and the numerical results of this mathematical model have shown that the motions of the interfacial flow are related to Weber numbers of system as well as characteristics of graphite bipolar plates and the gas diffusion layers of the PEMFCs.
Optimal Placement of Sensors and Actuators in Cluster Control of Acoustic Potential Energy in a Cavity
Authors: Jalali M. , Ohadi A. R.
Published: May 2012

This paper aims the cluster control of acoustic potential energy in a structural/acoustic cavity. The cavity consists of five rigid walls and one flexible panel with clamped boundary conditions on all four edges. It is desired to suppress the acoustic noise within the cavity, produced by a disturbing force or plane wave. In order to perform noise suppression, both acoustic and structural actuators can be used, while only acoustic sensors are necessary for measurement. Cluster control approach classifies acoustic and structural modes such that they interfere if and only if they belong to the same cluster. Providing methods to actuate and measure each of these clusters individually, cluster control enables us to implement a multi-SISO system as opposed to a MIMO system, which can significantly reduce computational load on the controller. This paper also investigates the optimal placement of sensors and actuators for further noise suppression. It is shown that optimization is critically important when cluster control method is used. Optimal placement of sensors and actuators helps to improve the noise suppression, without increasing the cost of control system equipments. In order to locate the optimum positions, the genetic algorithm (GA) is employed. The effect of optimization on acoustic potential energy suppression is discussed using numerical simulations.
Stability Analysis of a Multi-Degree of Freedom System Limit Cycles and Close Trajectories
Authors: Na´prstek Jir´i´
Published: May 2012

Limit cycles (LC) are important steady state response types of multi-degree of freedom (MDOF) systems. Problems of LC basic existence, their emerging and extinction are closely related with their stable/unstable character. A new analytical/iterative method of LC identification and portrait investigation has been developed together with a technique of stability assessment. It enables to distinguish the stable/unstable limit cycles and consequently to define the attractive and repulsive response fields. LC investigation and transition processes from/to the wide attractor are carried out in subspace which is normal to the limit cycle trajectory. Special orthogonal subsystem is constructed. It enables an effective investigation of an LC behavior in a close neighborhood of the basic trajectory. Some analogies and relations with Lyapunov exponent procedure are mentioned. The general theoretical background is demonstrated on an SDOF and later DDOF systems. Links with related areas of non-linear dynamics and some open problems are outlined.
Advanced Design of Screw Joints With Transverse Loading and Light Materials
Authors: Kopfer H. , Friedrich C. , Gerhard T.
Published: May 2012

Since long years threaded fastening systems are established all over the world and they will be of importance also in the future; general design rules are well known like VDI 2230 [14]. Today new materials [1] and numeric simulation tools lead to more detailed results and to significant improvements — the design of an optimized screw joint for tomorrow looks largely different compared to a traditional bolted joint calculation. Focusing transverse loads especially shape based joint design is suitable for highest loading capacity. Due to this it is necessary to investigate the local stressing and the behavior when loaded in such joints more in detail. The behavior is characterized by the elasticity of the materials of clamped components (e.g. steel or light metals), the resilience of the clamped parts as well as by the clearance between the clamped parts themselves. As a reference situation a typical geometry was modeled with bracket, pull rod and screw/bolt. Based on this the investigation focuses on the main influences on positive force transmission and proposes an approach for advanced design of the loading capacity. Important aspects are the consideration of more-dimensional stress state during loading and the evaluation of important design parameters for geometry variations. New products are using more and more light materials [1] which exhibit an increased sensitivity due to force transmission in component contact zones. This paper gives an overview about related criteria when designing fastened component systems with transverse loading. Numeric stress analysis with FEA calculates a detailed stress distribution with significant inhomogeneities. Finally, conclusions for future engineering design are drawn.
Numerical Investigation of Mixed Convective Flow Through a Vertical Duct With a Backward-Facing Step Using Nanofluids
Authors: Al-aswadi A. A. , Mohammed H. A. , Shuaib N. H.
Published: May 2012

Laminar mixed convective buoyancy assisting flow through a two-dimensional vertical duct with a backward-facing step using nanofluids as a medium is numerically simulated using finite volume technique. Different types of nanoparticles with 5% volume fraction are used. The wall downstream of the step was maintained at a uniform wall temperature, while the straight wall that forms the other side of the duct was maintained at constant temperature equivalent to the inlet fluid temperature. The wall upstream of the step and the backward-facing step were considered as adiabatic surfaces. The duct has a step height of 4.9 mm and an expansion ratio of 1.942, while the total length in the downstream of the step is 0.5 m. The Reynolds number was in the range of 0 ≲ Re ≤ 100. The downstream wall was fixed to be at uniform wall temperature of 20 °C higher than the inlet flow temperature. A recirculation region was developed straight behind the backward facing step which was appeared between the edge of the step and few millimeters before the corner which connect the step and the downstream wall. In the few millimeters gap a U-turn flow was developed opposite to the recirculation flow which mixed with the unrecirculated flow and travels along the channel. It is inferred that diamond nanofluid has the highest velocity in the vicinity to the heated wall.
Simulation of Red Blood Cell Mechanical Behavior in Optical Tweezers Experiment Based on a Particle Method
Authors: Ahmadian M. T. , Firoozbakhsh K. , Hasanian M.
Published: May 2012

Optical tweezers provide an accurate measurement technique for evaluating mechanical properties of the living cells and many experimental studies have been done to understand the behavior of cells due to external forces. Numerical studies such as finite element methods have been used in order to simulate mechanical behavior of the Red Blood Cells (RBCs). Recent studies have shown that the particle methods are useful tools to simulate the mechanical behavior of living cells. Since in microscopic scales, using discrete models are preferred than continuum methods, a particle-based method is used to simulate the deformation of RBC which is stretched by optical tweezers. The cytoplasm of RBC is modeled as a fluid and cell membrane is replaced by a set of discrete particles connected by springs. The results are comparable with previous observations of RBC optical tweezers experiments. It was observed that RBC viscoelastic characteristics are mainly associated with the cytoplasm fluidic properties. In order to understand the behavior and function of living red blood cells, this significant developed model could be implemented to RBC interaction within micocapillaries and constricted zones in blood flow.
An Investigation on the Flexural Sensitivity and Resonant Frequency of an AFM With Sidewall and Top-Surface Probes
Authors: Kahrobaiyan M. H. , Ahmadian M. T. , Haghighi P. , Haghighi A.
Published: May 2012

The resonant frequencies and flexural sensitivities of an atomic force microscope (AFM) assembled cantilever probe which comprises a horizontal cantilever, a vertical extension and two tips located at the free ends of the cantilever and the extension are studied. This probe makes the AFM capable of simultaneous topography at top-surface and sidewalls of microstructures especially microgears which leads to a time-saving swift scanning process. In this work, the effects of the sample surface contact stiffness and the geometrical parameters such as the ratio of the vertical extension length to the horizontal cantilever length and the distance of the vertical extension from clamped end of the horizontal cantilever on the resonant frequencies and flexural sensitivities are assessed. These geometrical effects are illustrated in some figures. The results show that the low-order vibration modes are more sensitive for low values of the contact stiffness but the situation is reversed for high values.
A Bio-Inspired Miniature Comb Sense Differential Microphone Diaphragm
Authors: Cui Weili , Miles Ronald N. , Su Quang , Homentcovsci Dorel
Published: May 2012

A highly innovative miniature silicon comb sense differential microphone diaphragm is described that is highly stable when subjected to various bias voltages [1]. The bio-inspired microphone diaphragm consists of a 1mm by 2mm stiffener-reinforced plate fabricated out of phosphorous doped polysilicon that is supported on a central hinge [2, 3, and 4]. Interdigitated comb fingers are formed around the perimeter at the ends of the diaphragm by reactive ion etching the polysilicon to create the gaps between the two sets of comb fingers. It is demonstrated with a fabricated prototype device that this design avoids many key limitations of capacitive microphones through use of a unique comb-sensing design and approach. It provides the means for design and construction of highly innovative capacitive microphones with enhanced sensitivity that can be readily and cost-effectively produced through silicon microfabrication. Potential applications include manufacturing of next-generation hearing aids, security devices, portable digital devices, cell phones and teleconferencing equipment.
Non-Premixed and Premixed Colorless Distributed Combustion for Gas Turbine Application
Authors: Arghode Vaibhav , Gupta Ashwani K.
Published: May 2012

Non-premixed and premixed modes of Colorless Distributed Combustion (CDC) are investigated for application to gas turbine combustors. The CDC provides significant improvement in pattern factor, reduced NOx emission uniform thermal field in the entire combustion zone for it to be called as a isothermal reactor, and lower sound levels. Basic requirement for CDC is mixture preparation through good mixing between the combustion air and product gases so that the reactants are at much higher temperature to result in hot and diluted oxidant stream at temperatures that are high enough to auto-ignite the fuel and oxidant mixture. With desirable conditions one can achieve spontaneous ignition of the fuel with distributed combustion reactions. Distributed reactions can also be achieved in premixed mode of operation with sufficient entrainment of burned gases and faster turbulent mixing between the reactants. In the present investigation two non-premixed combustion modes and one premixed combustion mode that provide potential for CDC is examined. In all the configurations the air injection port is positioned at the opposite end of the combustor exit, whereas the location of fuel injection ports is changed to give different configurations. The results are compared for global flame signatures, exhaust emissions, acoustic signatures, and radical emissions using experiments and flow field, gas recirculation and mixing using numerical simulations. Ultra low NOx emissions are observed for both the premixed and non-premixed combustion modes, and almost colorless flames (no visible flame color) have been observed for the premixed combustion mode. The non-premixed mode was also provided near colorless distributed combustion. The reaction zone is observed to be significantly different in the two non-premixed modes.
Development of an Underwater Remotely Operated Vehicle (ROV) for Surveillance and Inspection of Port Facilities
Authors: Gutierrez Luis B. , Zuluaga Carlos A. , Ramirez Juan A. , Vasquez Rafael E. , Florez Diego A. , Taborda Elkin A. , Valencia Raul A.
Published: May 2012

This work addresses the development of an underwater remotely operated vehicle (ROV), required to obtain reliable visual information, used for surveillance and maintenance of ship shells and underwater structures of Colombian port facilities and oceanographic research. The most relevant design constraints were evaluated considering environmental conditions, dimensional restrictions, hydrostatics, hydrodynamics, degrees of freedom and the availability of instrumentation and control hardware. The mechanical/naval design was performed through an iterative process by using computational tools CAD/CAE/CFD. The hardware architecture was divided in three layers: instrumentation, communications and control. The software was developed using ANSI C with Embedded Linux operating system. The guidance and navigation system used the Kalman filter to estimate the state of the vehicle. The vehicle can operate in manual and semi-automatic modes. In the semi-automatic, the position of a joystick is converted into the velocity set-points that are integrated to get the yaw and depth commands for the PID controllers. The rigorous design and a consistent construction processes allowed the development of a robust and reliable robotic system that constitutes an innovative product in Colombia.
Approach to Designing a Solar Concentrator for Small Scale Remote Power Application
Authors: Metwally Khaled , El-Gabry Lamyaa A. , Makhlouf Ahmed
Published: May 2012

A small-scale concentrated solar power unit was designed to provide electricity and hot water using an organic Rankine cycle for Egypt as part of an undergraduate capstone project. The system was designed for a target power output of 3 KW. It uses parabolic troughs to heat ethylene glycol used as the heat transfer fluid which absorbs heat in the trough collector and transfers it to the working fluid through a heat exchanger. The system consists of 9 parabolic troughs and a total aperture area of 67 square meters, providing the required 3 KW of energy to the ORC. One parabolic trough was manufactured to test its thermal efficiency according to ASHRAE standard 93-2003 and compare it to its calculated value. A simple microcontroller-based system was used to track the sun.
Characterization of Germanium Nanowires-Flexible Substrate Assemblies Integrated via Direct Synthesis Methods
Authors: Rodgers Justin , Edel Julia , Rivera Johan , Englander Ongi
Published: May 2012

Nanowires are successfully synthesized directly on two types of flexible substrates, Kapton and silicone, to yield integrated compliant assemblies. Reduced temperature catalyst-assisted chemical vapor deposition techniques enable the direct integration processes. The mechanical properties of these assemblies are evaluated using bending tests where tensile or compressive strains are applied to the samples. Crack formation in the form of channeling or debonding, typical of thin films on substrates, is observed. The allowable strain prior to mechanical failure is assessed.
An Investigation Into Quantifying Pressure Wave Oscillation in the Lung
Authors: Mussa J. , Al-Jumaily A. M. , Ijpma G.
Published: May 2012

Understanding pressure wave propagation in the lung is of importance for a number of medical devices including those for diagnostics and treatments. The main objective of this research is to quantify the transmitability of the airway tree with respect to pressure oscillations. Ovine lungs are casted to produce a hollow airway tree. Variable pressure oscillations and airflow are supplied at the trachea of the casted model and pressure oscillations are measured at the bronchioles. The study indicates that pressure waves with different frequencies can be delivered to different locations of the lung by controlling the pressure oscillation source to the lung.
Heat Transfer Enhancement of Backstep Flow by Means of EHD Conduction Pumping
Authors: Yazdani Miad , Seyed-Yagoobi Jamal
Published: May 2012

Electrohydrodynamics (EHD) conduction pumping takes advantage of the electrical Coulomb force generated by externally applied electric field and dissociated charges from electrolytes. The backstep flows that appear in certain types of MEMS application are not very efficient from the heat transfer standpoint due to the trapped circulation flow in the reattachment zone. This paper is a numerical study on the application of EHD conduction pumping as an auxiliary tool for heat transfer enhancement of backstep flows in macro- and micro-scale systems. An innovative electrode design with a dc electric potential difference is proposed with the primary motivation to reduce the volume of reattachment zone.
Decrease of the Energetic Consumption in Process Control
Authors: Castrillon Fabio , Vasquez Rafael E.
Published: May 2012

Several indexes to compare the performance of automatic control systems applied to specific processes are shown in control theory literature. Nevertheless, crucial aspects like the energetic cost to eliminate the controlled variable deviation and the work done by the final control element, are neglected. In this work, different control strategies such as conventional proportional-integral-derivative (PID) controllers, feed-forward control algorithms and internal model control techniques are compared. The comparison is made in an alimentary fluid heating process. The performance is measured by using the integral of the absolute value of the error, the settling time, the maximum deviation of the controlled variable, the work done by the final control element and the energetic cost associated with the manipulated variable. It is demonstrated how the additional control techniques can help to decrease the energetic operation costs. All the strategies can be implemented using typical industrial instrumentation.
High Speed Rotational Testing of Laminated Side Glazing for Occupant Containment
Authors: Herbst Brian R. , Oliver Arin A. , Meyer Steven E. , Phillips Donald R.
Published: May 2012

Recent research by the National Highway Traffic Safety Administration (NHTSA) on developing an ejection mitigation standard, Federal Motor Vehicle Safety Standard (FMVSS) 226, has led to an increased focus on occupant retention in the rollover accident mode. Research has long shown the benefits of keeping occupants contained in the vehicle as their risk of fatality increases five fold when they are ejected [1]. While restraint use, restraint performance and vehicle structural integrity are all components in occupant containment, the vehicle’s glazing system is the most likely component to fail in a rollover accident. Vehicle glazing failure usually creates large portals in the vehicle structure through which occupants can be ejected. The subject paper reviews previous work regarding testing and analysis of laminated automotive glazing and expands upon those studies with the presented high speed rotational testing. The performed study includes seven controlled, multirevolution tests of a partial sport utility vehicle (SUV) occupant compartment test fixture rotated about a fixed, longitudinal axis. The front doors of the fixture were modified by replacing the original equipment manufacturer (OEM) tempered glazing with High Penetration Resistant (HPR) annealed laminated glazing. Additionally, one of the door window frames was expanded and reinforced with an additional outboard sheet metal flange. Unrestrained Hybrid III 50th percentile male ATDs were placed in the front seating positions and rotated at roll rates of up to 644 degrees per second. ATD kinematics and interactions with the front window glazing were recorded and analyzed. When the laminated glazing did not fracture during early test sequences, the glazing was pre-fractured and re-tested under similar conditions. Under all test conditions, the laminated side window glazing was shown to contain the ATD.
Effects of Nonlinear Friction Wedge Damping on Freight Train Dynamics
Authors: Baruffaldi Leonardo B. , dos Santos Auteliano A.
Published: May 2012

Engineers pay great attention to comfort and performance issues, which are related to passenger trains suspension systems. Complex active shock-absorbing devices are developed and modern simulation tools are employed to determine car body vibrations and ride behavior. Freight train suspensions, however, were not given the same focus, presenting the same basic design for about 70 years now. Recent increases in pay-loads and train lines speed, and growing pressures to decrease maintenance costs, are slowly changing this scenario in such a way that numerical simulation methods are being more and more used. Most commercially available simulation software used by train manufacturers to address full vehicle behavior treats the friction wedge — the main damping element in the three-piecetruck suspension — as a weightless unidirectional force element like springs and dampers, which connects the wheel frames to the bolster that supports carbody load. This paper uses an improved friction wedge model to emphasize the importance of considering nonlinear characteristics of friction damping to vertical and longitudinal dynamics of a freight truck wagon modeled with multi-body dynamics.
The Co-Continuous Micro-Porous PLLA Scaffolds and Their Application for ACL Reconstruction
Authors: Zhang Qingwei , Zhang Wei , Yao Donggang , Lelkes Peter I. , Zhou Jack G.
Published: May 2012

Anterior cruciate ligament (ACL) reconstructive surgery is a major health concern world-wide because of a large aging population and increased occurrence of sport-related damage. Tissue engineering is a rapidly growing interdisciplinary field that offers a promising new approach for ACL repair. In order to overcome the shortages of current existing surgical fixation devices, we are combining gradient cellular structure (GCS) injection molding technique and biomedical engineering to develop novel surgical fixation devices (screw, anchor, plate, pin, staple, etc.) that not only incorporate bioactive materials such as growth factors, healing drugs and cells, but have natural bone GCS structure, intended to mimic the natural bone and promote bone tissue growth and eventually eliminate the defects associated with existing surgical fixation devices. In this work, a series of novel poly-L-lactic acid (PLLA) scaffolds with micro-porous structure were prepared by injection molding an immiscible polymer blend, with spatially controlled thermal conditioning to adjust the phase size from core to surface. The produced scaffolds were observed under SEM, which shows a co-continuous structure was created successfully through our method. The biocompatibility and the feasibility of produced micro-porous structural PLLA and PLLA/HA scaffolds as a matrix supporting cell growth tested by culturing murine osteoblasts cell line (7F2) for up to 9 days were assessed by Alamar Blue™ assay, which showed that the manufacturing process had no negative effects on cell proliferation. The cell attachment, spreading, migration and proliferation to confluence were assessed by fluorescent nuclear staining with Hoechst 33258. In order to evaluate the functional and cell biological applicability of the micro-porous structural PLLA scaffolds, a subcutaneous biodegradation test was performed through rat model for 1 week and 1 month time period, respectively. Our results showed that the micro-porous structural PLLA scaffolds are non-toxic, and they showed a mild foreign body reaction and complete fibrous encapsulation after implantation. Well created interconnected porous structure and biocompatibility suggest great potential of the micro-porous PLLA scaffolds in application for ACL reconstruction.
Hybrid-Nuclear Power: An Unexpected Energy Solution for the 21st Century
Authors: Keller Michael F.
Published: May 2012

America possesses hundreds of years of low-cost coal resources that are becoming increasingly unpopular due to climate-change concerns. The high cost of conventional nuclear power greatly hampers the building of new such facilities, while the promise of the nuclear gas reactor also remains out-of-reach as a result of technical and competiveness considerations. Hybrid-nuclear power is a breakthrough solution to the emerging energy and climate change dilemmas. This unique technology springs from the observation that roughly half the power produced by a combustion turbine is used to compress air. By using low-cost nuclear fuel and a highly efficient helium gas reactor system with a combustion turbine, power plant output is significantly increased, costs are appreciably lowered and emissions are dramatically reduced. The helium gas reactor marriage with the combustion turbine and coal gasification opens the door for the continued use of our most abundant and low-cost fuel resource, coal. This hybrid configuration dramatically reduces environmental impacts while also supporting the co-production of all manner of liquid transportation fuels, substitute natural gas, hydrogen, and process heat as well as industrial chemicals. Solar and energy storage applications are also readily supported by the hybrid’s inherent flexibility. Hybrid-nuclear energy relies on tried-and-proven technologies as well as the large body of knowledge developed over the 50 year history of nuclear reactors and combustion turbines. The unique characteristics of the hybrid-nuclear approach allow the technology to overcome the engineering, financial and regulatory obstacles that have long held back the full-scale commercial deployment of the high-temperature gas reactor. The emerging hybrid-nuclear technology readily supports energy independence and can simultaneously help revitalize the increasingly challenged US coal and nuclear industries.
Multiscale MD/LBM Simulations of Flow in Complex Nano/Micro Channels
Authors: Marsh D. D. , Vanka S. P.
Published: May 2012

This paper examines the fluid behavior in micro and nano sized channels by using a coupled Molecular Dynamics and Lattice Boltzmann solution method, implemented in a novel fashion on a Graphics Processor. Molecular Dynamics is well known for its ability to resolve phenomena in the near wall regions, where continuum assumptions are no longer valid, at the expense of computational power. Lattice Boltzmann is a mesoscale continuum-description solver that is very efficient and reduces to the Navier-Stokes equations, thereby being a logical choice to solve regions further from the wall. This method is parallelized to be run on the Graphics Processor, using NVIDIA’s CUDA programming language. Individually, Lattice Boltzmann methods are approximately 70× faster on the GPU than a modern CPU, Molecular Dynamics is about 5× faster. Higher resolutions are able to be simulated than previously performed due to the efficiency of this implementation. We analyze the results of straight channel Poiseuille flow using the hybrid solver and note the continuum breakdown is successfully predicted by the hybrid code in the form of density oscillations near the wall along with velocity slip conditions. Streamlines, contours and velocity profiles are utilized to illustrate these points. Future work includes expanding this solver’s capability to handle complex boundaries.
Design Methodology for Manufacturing Automation System Reconfiguration
Authors: Rahman Muhamad Arfauz A. , Mo John P. T.
Published: May 2012

The fluctuating customer demand especially in product requirements and system specifications these days requires system design engineers to configure and reconfigure the manufacturing system regularly. This paper elaborates a configuration study of a manufacturing system as well as illustrating basic design methodology of capturing user requirements and specifications for flexible reconfiguration in manufacturing automation system. The configuration study was conducted to accumulate various design outcomes from a given manufacturing process. The manufacturing process chosen for the study describes a simple yet easy to understand process in which groups of system design engineers were required to produce potential design configurations suitable for the process. The outcomes are then utilized to formulate a general rules for the configuration and reconfiguration methodology. The methodology presented is based on the steps and work descriptions provided by the user requirements and specifications. In order to simplify the configuration and reconfiguration works, method of capturing user requirements and specifications is required. The later idea of undergoing this research is to find suitable method to capture and manipulate the user requirements and specifications and later provide an optimum solution for the design of flexible and reconfigurable manufacturing automation system. Once completed, the methodology can be a value added advantage to the future of configuration and reconfiguration framework for the manufacturing automation system. In addition to that, the industry will benefit from the outcomes of the research by having the ability to optimize the system and minimizing the risk of investment of new system at a faster pace.
Fabrication of a Flexible Metal/Polymer Mold With Liquid Crystal Polymer Material for Hot-Embossing Process
Authors: Lu Haijing , Ang Xiao Fang , Liu Hongping , Sun Zheng , Wei Jun
Published: May 2012

A flexible polymer is considered as an alternative of low-cost mold materials. Molds with a high density aspect ratio, smooth surface, vertical sidewalls and lightweight have been fabricated and it is easy-to-use features in the hot embossing process. The study also indicated that the flexible metal/polymer mold could be used for thermoplastic polymer patterning with high fidelity and low cost. Using the flexible metal/polymer mold, 10um and 5um structures were fabricated.