bluuebunny/crossref_metadata_2025 huggingface dataset:
Emission Characteristics of DI CI Engine Fuelled With High FFA CRBO Blend
Authors: Saravanan Subramani , Prasanth Vallikat Madathil , Nirup Philip , Nagarajan G. , Lakshmi Narayana Rao G.
Published: August 2009

In this investigation high FFA CRBO a renewable non-edible vegetable oil was tested to find its suitability as a CI engine fuel in its blended form. A dilute blend was prepared by mixing it with petroleum diesel in volume basis [20% CRBO + 80% No.2 petroleum diesel]. The main objective of this investigation is to study the performance and emission characteristics of this high FFA CRBO blend by employing it as a fuel for diesel engine. Tests were conducted on a naturally aspirated DI stationary diesel engine coupled to a swinging field dynamometer. Emissions were measured by using MRU Delta 1600 L gas analyzer. Variations in the emission of UBHC, CO, NOX and smoke density were found for different loads and compared with diesel. It was observed that when operating with CRBO blend, engine emissions levels are reduced significantly than that of diesel. When compared with diesel fuel, NOx emission, UBHC emission and smoke density for CRBO blend were lower with slight increase in CO emissions. It was also observed that the variations in brake thermal efficiency between CRBO blend and diesel were minimum at all operating conditions. From the experimental results it can be concluded that as a dilute blend higher FFA CRBO has an ability to replace petroleum diesel partially as the engine emissions were reduced significantly with minor loss in power.
Modeling of Motorcycle Anthropometric Test Device Neck Using Reverse Engineering Technique
Authors: Bhosale Prashant V.
Published: August 2009

In developing countries like India there are very limited resources for conducting actual crash tests on a motorcycle with dummy installed and it is also rare to get the design details of every object used in the actual crash tests conducted elsewhere in the world. With these limitations, safety of motorcyclist was studied using Finite Element (FE) Analysis and FE models of the objects under consideration were developed by reverse engineering technique wherever possible. In contrast to automobile occupants, a motorcyclist is unconstrained and can follow enumerable trajectories depending on the crash scenario. Airbag as a safety device for motorcyclist is under consideration for reducing fatality of the motorcyclist during the crash [1]. To arrive on any conclusion with reasonable accuracy on injury prediction for motorcyclist exposed to deploying airbags, the dummy neck construction should be more biofidelic in nature. This led to development of the Motorcycle Anthropometric Test Device (MATD) neck, which can accommodate different postures of the motorcyclist. The FE model of MATD neck was developed using HyperMesh™ [2] by estimating dimensions of each part of the MATD neck from the photographs available and following construction details specified in ISO13232 standards [3]. Overall performance of the MATD neck is dependent on the properties of mid section four rubber disks made up of Adiprene polyurethane material [4]. The material properties of different grades of Adiprene polyurethane available on internet site of the Crompton Corporation [5] were input to the MATD neck model with constraint that the weight of the MATD neck remains 1.55±0.1kg. Simulations for various tests specified in ISO13232 were run using Pamcrash™ [6]. Finally it was found that the MATD neck model satisfied all the corridors specified for Frontal Flexion, Extension, Lateral Flexion and Torsion tests as mentioned in ISO13232 standards when Adiprene LF1700A material properties were used for four mid section rubber disks.
Formation of Carbon Nanotube-Polymer Composites With Different Concentrations of Polystyrene Solution
Authors: Yung K. P. , Wei J. , Tay B. K.
Published: August 2009

In this study, polystyrene was mixed with toluene by ratios of 1 wt%, 2 wt%, and 3 wt% to create polystyrene solutions. CNTs-polymer composites have been fabricated by introducing polymeric material into the CNT film grown by plasma enhanced chemical vapour deposition (PECVD). The nanotubes act as conductive filler to the composite and resulting in increases in surface conductivities. Depending on the concentration of the polystyrene solution, the increases in conductivity varied. It is shown that the surface conductance is lower for CNT-polymer composite with higher concentrated polystyrene solution.
Fuzzy Control of an Electric Arc Furnace Off-Gas Process
Authors: Hasannia A. , Esteki H.
Published: August 2009

Electric arc furnaces are used to make steel from scrap iron in steel industry. Nowadays, the aim of more researches in this area is to increase yield of furnace and it’s compatibility with environment. One of the methods to achieve these purposes is to control the off-gas system as relative pressure in furnace would be kept negative. Because the combustion gases inside the furnace must not leak into the plant environment. However for preventing of loss of energy, the amount of this negative number must be small. In this paper, new intelligent control method named fuzzy emotional control, applied to off-gas system to control the relative pressure in the furnace and its result is compared to other methods.
Using Improved DSMC Method in Simulating for the Heat and Mass Transfer in Microchannels
Authors: Ye J. J. , Yang J. , Tang P. , Zheng J. Y. , Li W. Z. , Lam C. K. , McKenna M. , Ma Y. B.
Published: August 2009

Micro-electro-mechanical systems (MEMS) and nano-electro-mechanical systems (NEMS) have become the focus of a great deal of attention in recent years. The flow and heat behaviors of micro-machines are usually different from that of macro-machines. In this paper, the heat and mass transfer characteristics of rarefied nitrogen gas flows in microchannels have been investigated using improved DSMC method. The influence of aspect ratio and wall temperature on the mass flowrate and wall heat flux in microchannels are studied parametrically. In order to examine the aspect ratio effect on heat and mass transfer, the wall temperature is set constant at 350 K, and the aspect ratio of the microchannel varies from 5 to 20. The results show that as the aspect ratio increases, the velocity of the flow decreases, and the mass flowrate also decreases. In a small aspect ratio channel, the heat transfer occurs throughout the microchannel, and as the aspect ratio of the microchannel increases, the region of thermal equilibrium becomes larger. To investigate the effects of wall temperature on heat and mass transfer, the aspect ratio of the microchannel is held constant at 10 and the wall temperature is changed from 300 K to 800 K. The results show that, when the wall temperature increases, the pressure increases slightly and the number density drops rapidly near the inlet. In addition, the Knudsen number increases as the wall temperature increases. It indicates that the increasing wall temperature of microchannel enhances the rarefaction of the gas flow. Moreover, as the wall temperature increases, the mass flowrate decreases, and the temperature will increase more rapidly near the inlet, with more heat transfer between the gas flow and the wall.
Flow Behavior and Flow Boiling Heat Transfer in Thin-Rectangular Mini-Channels
Authors: Koizumi Yasuo , Ohtake Hiroyasu , Yamada Tomonari
Published: August 2009

Boiling heat transfer of thin-rectangular channels of the width of 10 mm has been examined. The height of the flow channel was in a range from 0.6 mm to 0.4 mm. Experimental fluid was water. Bubbly flow, slug flow, semi annular flow and annular flow were observed. The flow pattern transition agreed well with the Baker flow pattern map for the usual sized flow path. The critical heat flux was lower than the value of the usual sized flow channel. The Koizumi and Ueda method predicted well the trend of the critical heat flux of the present experiments. At the critical heat flux condition, the heat transfer surface was covered by liquid slug, a large bubble pushed away the liquid slug, a dry area was formed on the heat transfer surface and then liquid slug came around to cover the heat transfer surface again. This process repeated rapidly. Following this observation, a heat transfer surface temperature calculation model at the critical heat flux condition was proposed. The calculated result re produced the experimental result.
Design of a Fuzzy Logic Controller Using ANFIS for Accurate Position Control of a Pneumatic Servo System
Authors: Dhami S. S. , Bhasin S. S. , Mahapatra P. B.
Published: August 2009

A methodology for designing a Sugeno type Fuzzy Logic Controller (FLC) for accurate position control of a pneumatic servo system is presented. Adaptive Neuro Fuzzy Inference System technique is employed to construct a fuzzy inference system whose membership function parameters are tuned using a training data set comprising of input/output signal of the pneumatic servo system with proportional control. Hybrid backpropogation-least square algorithm is used for training of the Fuzzy Inference System (FIS). The resulting FIS optimally projected the behavior of training data set. To obtain the desired steady-state response, the fuzzy inference system is further tuned using the expert knowledge of the input/output response of the system. The system response for various reference inputs is compared quantitatively with that of the system without fuzzy logic controller, and excellent improvement in steady-state response is observed.
Process Technology Concerning the Coupled Solid-Liquid Industrial Waste Combustion for the Paper Industry
Authors: Prisecaru Tudor , Prisecaru Malina , Georgescu Manuela Elena , Popa Elena , Ciobanu Cristina
Published: August 2009

The paper present the research concerning technical possibilities to tamp the solid industrial waste coming out from an already refurbished paper plant in Adjud, Romania, in order to reduce the overall costs of the necessary landfill deposits and to create a real income by producing energy. An infrared system of a FLIR S65 videocamera (7–14 μm) and double wave length OMEGA OS3750 pyrometer (0.9–1.5 μm) have been used in order to assess the best thermal regime to ignite and to control the burning process of the industrial refuse.
An Analysis of Pallet Truck Accidents
Authors: Berry Thomas A.
Published: August 2009

This paper presents an analysis of more than 700 pallet truck accidents that occurred over a period of more than 20 years. Information will be presented with respect to the operator position, the injury type and severity as well as the type of incident that was involved. Discussion will address the operator protection offered by different designs of pallet trucks.
The Capture, Assessment and Communication Tool for Uncertainty Simulation (CACTUS) in Complex Systems
Authors: Farhangmehr Farzaneh , Tumer Irem Y.
Published: August 2009

The design and development cycle for complex systems is full of uncertainty, commonly recognized as the main source of risk in organizations engaged in design and development. One of the challenges for such organizations is assessing how much risk (cost, schedule, scope) they can take on and still remain competitive. The risk associated with the design of complex systems is fundamentally tied to uncertainty, which may lead to suboptimal performance or failure if unmanaged. By understanding the sources of uncertainty in all stages of complex system design, decision-makers can make more informed choices and identify “hotspots” for reducing risks due to uncertainty by reallocating resources, adding safeguards, etc. There are two major categories of uncertainty (certain uncertainty) classification in the design of complex systems: Knowledge/epistemic uncertainty and Variability/Aleatory uncertainty. The intersection of these two sets is ambiguity uncertainty and the outside is what we don’t know we don’t know (uncertain uncertainty). By setting detailed definitions, we can reduce the ambiguity uncertainty. Furthermore, we can subdivide knowledge uncertainty into model, ambiguity and behavioral uncertainty, and subdivide variability uncertainty into natural randomness, ambiguity and behavioral uncertainty. We can go further and find subcategories for model and behavioral uncertainty. Using this classification for uncertainty, this paper proposes the “Capture, Assessment and Communication Tool for Uncertainty Simulation” (CACTUS) for assessing, capturing, and communicating risks due to uncertainty during complex system design. CACTUS has columns to identify sources, location, severity and importance of uncertainty in stages of design. By applying CACTUS, decision-makers will be able to find answers to the following questions for each type of uncertainty included in the design process: 1 - Where is uncertainty from? (i.e., Sources); 2 - In which stages of design does uncertainty appear? (i.e., Location); 3 - What is its severity?; and, 4 - What is its importance? The hypothesis of this research is that, by using CACTUS, design organizations can capture, assess, and efficiently and effectively communicate uncertainty through their design processes, and as a result, improve their capacity for delivering complex systems that meet cost, schedule, and performance objectives. The fundamental steps of the methodology are illustrated by using a concurrent design case study from NASA’s Project Design Center.
On a General Approach to Free Vibrations Response of Integrally-Stiffened and/or Stepped-Thickness Rectangular Plates or Panels
Authors: Yuceoglu Umur , Javanshir Jaber , Guvendik O¨zen
Published: August 2009

This study is mainly concerned with a “General Approach” to the “Theoretical Analysis and the Solution of the Free Vibrations Response of Integrally-Stiffened and/or Stepped-Thickness Plates or Panels with Two or more Integral Plate Stiffeners”. In general, the “Stiffened System” (regardless of the number of “Plate Stiffeners”) is considered to be composed of dissimilar “Orthotropic Mindlin Plates” with unequal thicknesses. The dynamic governing equations of the individual plate elements of the “System” and the stress resultant-displacement expressions are combined and algebraically manipulated. These operations lead to a new “Governing System of the First Order Ordinary Differential Equations” in “state vector” forms. The new “Governing System of Equations” facilitates the direct application of the present method of solution, namely, the “Modified Transfer Matrix Method (MTMM) (with Interpolation Polynomials)”. As shown in the present study, the “MTMM” is sufficiently general to handle the “Free Vibrations Response” of the “Stiffened System” (with, at least, one or up to three or four “Integral Plate Stiffeners”). The present analysis and the method of solution are applied to the typical “Stiffened Plate or Panel System with Two Integral Plate Stiffeners”. The mode shapes with their natural frequencies are presented for the “Isotropic Al-Alloy” and “Orthotropic Composite” cases and for several sets of support conditions. As an additional example, the case of the “Stiffened Plate or Panel System with Three Integral Plate Stiffeners” is also considered and is shown in terms of the mode shapes and their natural frequencies for one set of the boundary conditions. Also, some parametric studies of the natural frequencies versus the “Stiffener Thickness Ratio” and the “Stiffener Length (or Width) Ratio” are investigated and are graphically presented.
An Energy-Efficient Node Activation Scheme for Reconfigurable Sensor Networks
Authors: Yeh Cheng-Tai , Gao Robert X.
Published: August 2009

This paper presents an energy-efficient node activation scheme that reduces the cost in recharging energy-depleted sensor nodes in a wireless sensor network. The network operation combined with node activation is modeled as a stochastic decision process, where the activation decisions directly affect the energy efficiency of the network. An analytical model is developed to formulate the network operation as a Semi-Markov Decision Process (SMDP) by assuming exponentially distributed recharging and discharging times. Using this model, an optimal activation policy is obtained that minimizes the recharging rate. To evaluate the developed node activation scheme, simulation was performed for both a correlated and an independent sensor network model. In the correlated model, a 72% reduction of recharging rate has been achieved, compared with no intelligent node activation. The approach presented provides a framework for designing wireless sensor networks where energy efficiency is of critical importance.
Green Manufacturing: Pump Free Hydraulic Drive Clamping Device With Zero Energy Consumption in the Cutting Process
Authors: Zhong K. M. , Su D. N. , Li X.
Published: August 2009

This paper introduces a pump free hydraulic drive clamping technique with zero energy consumption in the cutting process, the principle of which is to clamp the workpiece by an over-critical self-locking force-amplifying toggle mechanism which is driven by the significant displacement which is about one hundred times of the micro-displacement of giant magnetostrictive materials. The amplified displacement is the effect of the stroke-amplifying device based on area effect of Pascal theory. This new clamping technique of new concept not only features very simple structure and fast responsiveness in clamping process, but also has the following environment-friendly characteristics: (1) The clamping is significantly energy saving without energy consumption in the cutting process as well as safe and reliable due to the self-locking function of the over-critical force-amplifying toggle mechanism. (2) The noise and other pollutions generated by oil fluid leakage and volatilization are negligible because no hydraulic pump and open oil tank are used.
MLHP: A High Heat Flux Localized Cooling Technology for Electronic Substrates
Authors: Dhillon Navdeep S. , Pisano Albert P. , Hogue Christopher , Hopcroft Matthew A.
Published: August 2009

A novel microscale device based on phase change technology is proposed for localized cooling of very high heat flux electronic substrates. Device physics and salient design features are elucidated and a numerical model is developed to predict device performance and optimize the design parameters. The Micro-columnated Loop Heat Pipe (MLHP) consists of evaporator and condenser sections connected by liquid and vapor microchannels, all fabricated on a silicon wafer using MEMS microfabrication techniques. A novel micro-columnated wick is designed to prevent wick dryout to enhance reliability. The MLHP operates using capillary pumping thus requiring no external power and provides enhanced localized cooling capabilities by interfacing directly with a heat producing chip. Recent studies on microscale fluid flow and heat transfer physics in microchannels are implemented in a numerical model to predict the performance of the MLHP. A detailed design optimization study is performed to maximize the device heat flux carrying capacity, which at 1400 W/cm2 is a considerable improvent on all of the existing high heat flux cooling technologies.
Nanopore Concentration Polarization
Authors: Talasaz AmirAli H. , Zangle Thomas A. , Santiago Juan G.
Published: August 2009

Nanopores offer the potential for label-free analysis of individual proteins and low cost DNA sequencing. In order to design and evaluate nanopore devices, an understanding of nanopore electrokinetic transport is crucial. However, most studies of nanopore electrokinetic transport have neglected the effects of concentration polarization (CP) in the bulk fluid surrounding the pore. In this paper, we present a computational model which demonstrates the effects of CP on the background electrolyte in nanopore devices with tip diameters of 40–100 nm. We also present direct experimental observation of the distribution of an anionic dye in the vicinity of a conical nanopore. These results indicate that CP in a nanopore system can affect concentration distributions in the bulk solution tens of microns away from the pore, suggesting that typical boundary conditions used to model nanopore electrokinetic transport are incomplete.
Designing Controller System for Integrated Solar Power Plant Using Fuzzy Method
Authors: Shahmaleki Pourya , Mahzoon Mojtaba , Shahmaleki Parmis
Published: August 2009

A parallel combination of oil cycle and fossil fuel boiler is utilized in the integrated solar power plant (ISPP) to achieve better efficiency and reduce cost of electricity generation. There are two cycles, oil and steam, in an ISPP. To enhance performance and achieve control optimization more precise simulation for power plant dynamics are needed. In this paper, a dynamic simulation of an ISPP was developed using the HYSYS software. To enhance efficiency and reduce damage to turbine due to flow rate variations of produced steam by oil cycle, the prime control requirement is to maintain the inlet steam temperature and flow rate of the turbine at a constant value. In this paper, to control the complete oil cycle, two fuzzy controllers are proposed: continuous controller and a switching controller. In steam cycle three controllers are proposed for boiler and reboiler heat exchanger. These controllers are used to maintain constant the inlet steam temperature and flow rate to turbine. Simulation results of the integrated solar power plant and the control systems show that the applied control systems can manage the oil and steam cycles in different situations.
Elevated Temperature Fatigue Prediction Model for AISI 4340 Gun Steel
Authors: Goblish Adam , Delfanian Fereidoon , Feldhacker John , Hu Zhong
Published: August 2009

Cannon barrel life can be maximized by fully understanding the correlation between temperature and hoop stress and their relation to crack growth. Use of elevated temperature fatigue to predict failure of a gun barrel based on the number and type of rounds along with temperature data will both maximize the usable life of a cannon barrel and maintain a safe operating environment the men and women using these cannons. This analysis will help increase the usable life of large caliber cannon barrels; round data that is collected throughout the life of a cannon barrel will be used to determine the proper time to decommission the barrel. Experimental data was collected utilizing an MTS 858 fatigue system applying low cycle fatigue analysis. Numerous operating temperatures and stresses were calculated from various cannon round types and used to determine test parameters. From this data, a correlation was generated between stress and temperature to predict life expectancy of the test specimens. Several specimens were then cycled for various temperature and pressure combinations, thereby verifying the accuracy of the prediction model. Data was collected using methods set forth in ASTM E466-07 which dictates the standard practice for force-controlled fatigue testing. Data was analyzed using Minitab for development of the life cycle prediction model. Since the accuracy of the model dictates its reliability, this was used to provide a safety cushion to ensure that failure does not occur prior to the expected time.
Numerical Simulation of Plunge Force During the Plunge Phase of Friction Stir Welding and Ultrasonic Assisted FSW
Authors: Park Kwanghyun , Kim Bongsuk , Ni Jun
Published: August 2009

Ultrasonic assisted friction stir welding (UaFSW) is an hybrid welding technique, where high frequency vibration is superimposed on the movement of a rotating tool. The benefit of using ultrasonic vibration in the FSW process refers to the reduction in the welding force and to the better welding quality. The UaFSW system is being developed and its mechanism needs to be understood using both the experiments and the numerical simulations. In this paper, FE simulations of FSW and UaFSW using ABAQUS/Explicit were carried out to examine plunge forces during the plunge phase of FSW and UaFSW, respectively. First, the simulations of the conventional FSW process were validated. Then, simulation of UaFSW process was performed by imposing sinusoidal horizontal ultrasonic vibrations on the tool.
A Numerical Study of Ammonia-Water Absorption Into a Constrained Microscale Film
Authors: Cardenas Ruander , Narayanan Vinod
Published: August 2009

A one-dimensional, steady state, semi-empirical model of an ammonia-water microscale bubble absorber is presented. The geometry consists of a microchannel through which a solution of ammonia-water flows. Ammonia vapor is injected through one of the walls of the channel. A counter flowing coolant solution removes the heat generated due to absorption from the opposite wall. The 1-D, steady state species and energy transport equations are solved to yield, along the length of the channel, concentration and temperature profiles of the solution stream and the temperature profile of the coolant fluid stream. Values for the overall heat transfer coefficient from experimental results are used in this model. A parametric study of fluid and geometrical parameters based on the model is presented. The varied fluidic parameters include the mass flow rates of the weak solution, coolant, and vapor, the inlet coolant temperature, and the weak solution concentration. Two variations of the vapor distribution that resulted from a geometrical variation of the porous plate are considered: (a) variation in length of the non-porous section, and (b) variation in the number of intermittent sections in which there was no injection of vapor. Trends of the parametric study were consistent with those of experiments. A salient result of the parametric study indicates that incomplete absorption occurs with an increase in weak solution flow rate due to the decrease in residence time within the microchannel for absorption. At a specific fixed flow condition, a single porous section followed by a non-porous section provides the optimal vapor distribution for absorption within the channel. The length of this non-porous section for optimal absorption within the channel is also determined using the model.
Integration of Catalytic Combustion and Heat Recovery With Meso-Scale Solid Oxide Fuel Cell System
Authors: Maxey Christopher J. , Jackson Gregory S. , Reihani Seyed-Abdolreza Seyed , Decaluwe Steven C. , Patel Siddharth , Veeraragavan Anand , Cadou Christopher P.
Published: August 2009

To facilitate high-power density operation of a meso-scale solid oxide fuel cell (SOFC) system, fuel processing and anode exhaust catalytic combustor with waste heat recovery are critical components. An integrated modeling study of a catalytic combustor with a solid oxide fuel cell and a catalytic partial oxidation (CPOx) reactor indicates critical aspects of the butane-fueled system design in order to ensure stable operation of the SOFC as well as the combustor and CPOx reactor. The modeled system consists of: 1) a Rh-coated ceramic foam catalytic partial oxidation reactor, 2) a SOFC with a Ni/YSZ structural anode, a dense YSZ electrolyte, and a LSM/YSZ cathode layer, and 3) a Pt-coated anode exhaust combustor with waste heat recovery. Model results for a system designed to produce < 30 W electric power from n-butane show how the design of the inlet-air cooled catalytic combustor can maximize combustion efficiency of the anode exhaust and heat recovery to the system inlet air flow. The model also shows the need to minimize heat loss in the air flow passages in order to maintain stable SOFC operation at 700 °C or higher. There is a strong sensitivity of the system operation to the SOFC operating voltage as well as the overall air to fuel ratio, and these sensitivities place important bounds on the range of operating conditions.
Airpath Controls of Turbocharged Diesel Engines With Disturbance Input Observers
Authors: Liu Chia-Shang
Published: August 2009

To achieve stringent emission regulation standard and deliver desired engine performance, modern diesel engines are equipped with an exhaust gas recirculation system and a turbocharger to regulate the fraction of exhaust gas and intake manifold pressure. Due to the actuator coupling effect and the high nonlinearity of the system behavior, it is difficult to apply classical control designs in such a case. To solve this issue, this paper presents a disturbance observer based approach for the airpath controls of turbocharged diesel engines. The disturbance observer is synthesized with the controller to compensate the unknown dynamics and system uncertainties of the engine plant that will make the controller more robust and less dependent on the accuracy of mathematical modeling. The performance of proposed observer and controller schemes are demonstrated by numerical simulation with a full order diesel engine model.
Reduced-Complexity Dual-Arm Robotic Manipulator for Compact Substrate-Handling Platforms
Authors: Hosek Martin , Krishnasamy Jay
Published: August 2009

The design of a reduced-complexity dual-arm robotic manipulator for compact substrate handling platforms is presented. The manipulator utilizes a common component, which forms the left upper-arm link and right upper-arm link of the robot arm, and two forearm links, each of which carries an end-effector and can move substrates in the radial as well as circumferential directions. A unique feature of the design is that a novel transmission mechanism is used to couple a single drive motor to the two forearm links. The advantage of using such a transmission mechanism is that one less motor is required to achieve the desired motion. This article outlines the concept of the robotic manipulator and the transmission mechanism, presents a kinematic and dynamic model of the combined system, and discusses a design methodology so as to satisfy the motion requirements in a compact substrate-handling platform. The feasibility of the proposed concept is demonstrated on a fully functional prototype.
Coating Characterzation in CrN Deposited by Magnetron Sputtering Method on AISI 316 Steel
Authors: Hilerio I. , Vite M. , Moreno M. , Barron M. A. , Jime´nez H. , Vazquez B.
Published: August 2009

Chromium Nitride (CrN) thin films were deposited on AISI steel 316 substrates by means of the reactive magnetron sputtering method. CrN films were produced under two different conditions. In the first one, the substrate was heated by a DC source. For the second coating a negative substrate bias voltage was applied. X ray diffraction, quantitative energy dispersion and scanning electron microscope were employed to characterize the two different phases, their chemical composition as well as their microstructure. In addition, a microhardness test was carried out. The results show that a better phase formation of CrN thin films was achieved when a heating source was present (first case). Both coatings presented homogeneous surface. Their compositions show differences even when the gases flowing are the same in composition. Regarding to the hardness test results, there can be found a higher value when using a heating source.
Nodal Position Finite Element Method and its Application to Dynamics of Cable Systems
Authors: Zhu Zheng H.
Published: August 2009

The current approaches to the design of the handling of towed cable systems onboard surface ships rely heavily on empirical methods and time-consuming/expensive prototype testing. This paper presents a new nodal position finite element method (FEM) as a design tool to simulate the dynamics of towed body system effectively. By solving for the position of cable directly instead of indirectly via the displacement, the new FEM does not need to decouple the elastic deformation from the rigid body rotation and thus eliminates the error source arising from the linearized incremental approximation in existing FEM. Analysis results demonstrate the new FEM algorithm is simple and robust by comparing with numerical benchmark test and experiments including sea trial data.
Dynamic Stability Analysis of Aerial Refueling Hose/Drogue System by Finite Element Method
Authors: Zhu Zheng H. , Meguid Shaker A.
Published: August 2009

The present work investigates the effect of pertinent parameters such as the hose tension, tow point disturbance and vortex wake on the dynamic stability of the aerial refueling hose and drogue system by using the finite element method with an accurate and computationally efficient three-noded, curved beam element. The analysis results show that the conventional spectrum method is inappropriate for the dynamic stability analysis of the aerial refueling hose/drogue system. This is because the mechanism of instability due to the tow point disturbance is not the resonance of the refueling hose/drogue system but the wave propagation along the hose absorbing energy from the airflow as it travels downstream from the tow point, if the propagation speed is less than the airflow speed. The study also demonstrates that the vortex wake has a significant impact on the dynamics of the system. The short hose system will orbit with the vortex and the orbiting behavior will diminish as the hose length increases.
Analytical Prediction of Periodic Motions in a Machine Tool With Loss of Effective Chip Contact
Authors: Gegg Brandon C. , Suh Steven C. S. , Luo Albert C. J.
Published: August 2009

This study applies a discontinuous systems theory by Luo (2005) to an approximate machine-tool model. The machine-tool is modeled by a two-degree of freedom forced switching oscillator. The switching of the model emulates the various types of dynamics in a machine-tool system. The main focus of this study is the loss of effective chip contact and boundaries of this motion. The periodic motions will be studied through the mappings developed for this machine-tool. The periodic motions will be numerically and analytically predicted via closed form solutions. The phase trajectory, velocity, and force responses are presented.
A Supervisory Fuzzy-PID Controller for a MIMO Biped Robot Balance in Frontal Plane
Authors: Zomorodi-Moghadam Hesam , Haghshenas-Jaryani Mahdi , Farahmand Farzam
Published: August 2009

In this paper we propose to control a bipedal robot in an unstable position by means of a PID controller that gains are turned by a fuzzy logic system. For that, a model of planar 3 linked segment consisting of limb, trunk and extended arms with fixed base is used. Fuzzy if-then rules are constructed based on human expert knowledge and biomechanics studies for tuning of PID’s gain. For construction of tuning rules, we have developed an optical measuring system to record experimental data of balance keeping of a human in an unstable position. The control model is based on three sets of different global variables: (1) limb orientation and its derivative, (2) trunk/upper attitude and its derivative, and (3) orientation of extended arms and its derivative. In this study, we consider only side to side robot’s balancing and we also demonstrate, by simulation results, that the proposed control model is stable in presence of external disturbance. Finally we have compared the simulation results with the experiments to show the similarity of the proposed system with the human balance keeping task.
Representing Common-Cause Failures in the SAPHIRE Software
Authors: Smith Curtis
Published: August 2009

Currently, the risk analysis software SAPHIRE has implemented a common-cause failure (CCF) module to represent standard CCF methods such as alpha-factor and multiple Greek letter approaches. However, changes to SAPHIRE are required to support the Nuclear Regulatory Commission’s 2007 “Risk Assessment Standardization Project” CCF analysis guidance for events assessment. This guidance provides an outline of how both the nominal CCF probabilities and conditional (e.g., after a redundant component has failed) CCF probabilities should be calculated. Based upon user-provided input and extending the limitations in the current version of SAPHIRE, the CCF module calculations will be made consistent with the new guidance. The CCF modifications will involve changes to (1) the SAPHIRE graphical user interface directing how end-users and modelers interface with PRA models and (2) algorithmic changes as required. Included in the modifications will be the possibility to treat CCF probability adjustments based upon failure types (e.g., independent versus dependent) and failure modes (e.g., failure-to-run versus failure-to-start). In general, SAPHIRE is being modified to allow the risk analyst to define a CCF object. This object is defined in terms of a basic event. For the CCF object, the analyst would need to specify a minimal set of information, including: - The number of redundant components; - The failure criteria (how many component have to fail); - The CCF model type (alpha-factor, MGL, or beta-factor); - The parameters (e.g., the alpha-factors) associated with the model; - Staggered or non-staggered testing assumption; - Default level of detail (expanded, showing all of the specific failure combinations, or not). This paper will outline both the theory behind the probabilistic calculations and the resulting implementation in the SAPHIRE software.
Brownian Dynamics Simulations of a Dispersion Composed of Two-Types of Spherical Particles (for Development of a New Technology of Improving the Visibility of Rivers and Lakes)
Authors: Satoh Akira , Taneko Eiji
Published: August 2009

We have carried out Brownian dynamics simulations of sedimentation phenomena of a dispersion composed of two-kinds of spherical particles in water under the gravity field. This study may be the first step to develop a new technology which enables us to improve the visibility of rivers and lakes. In the present study, we have modeled sub-micrometer-dimension particles, or dirty particles in lakes, as small spherical particles, and capturing particles as large spherical particles; these two kinds of particles conduct Brownian motion in water, and large particles adsorb small particles to sediment gradually toward the bottom in the gravity field. From the results of Brownian dynamics simulations, the influences of Brownian motion, particle-particle interaction forces, the size of each particle, and the gravity force on the performance of the adsorption of large particles have been discussed. In addition, we have discussed what the most appropriate situation of large particles is to accomplish the most effective adsorption rate or improve the visibility of water most effectively in terms of capturing particles. The most important conclusion derived from the present results is that, in order to improve the capturing performance, the Brownian motion of large particles have to be activated in an appropriate number density without losing the influence of the gravity.
H
∞ Frequency-Domain Identification of Flight Control System
Authors: Yau D. T. W. , Fung E. H. K. , Wong Y. K.
Published: August 2009

In this paper, H∞ identification is performed in frequency domain for the longitudinal pitch and speed channels of a commercial Boeing 747 transport aircraft flying at a particular flight condition. The plant (i.e. the longitudinal pitch and speed transfer functions) to be identified is a causal, bounded-input/bounded-output (BIBO) stable, single-input/single-output (SISO), linear time-invariant (LTI) discrete-time system. The frequency response data is generated by simulation of the plant transfer functions and is corrupted by unknown but bounded measurement noise. An identification algorithm is used to map the experimental data into an identified model such that the worst case identification error converges in a particular sense. In this paper, untuned linear algorithm and two-stage nonlinear algorithm are used respectively for computing the identified models for the pitch and speed transfer function of the aircraft. Different window sequence (rectangular, triangular, traperzoidal, etc.) are used in these algorithms. The error response and worst case error bound computed by these two algorithms are also compared. The paper demonstrates the effectiveness of the two algorithms for computing the identified model. Unlike classical identification which is inadequate for robust control, the results of H∞ identification can be used for designing the H∞ robust controllers.
Thermal Analysis of Natural-Convection-Cooled Heat Sinks Using the Volume-Averaging Approach
Authors: Byon Chan , Kim Sung Jin
Published: August 2009

In this paper, a compact modeling method for predicting the thermal characteristics of vertical plate fin heat sinks under natural convection is presented. The plate fin heat sink is modeled using the volume-averaging approach. The solutions for velocity and temperature distributions are obtained by solving the averaged governing equations. In order to validate the model proposed in this paper, experimental investigations are performed. The resulting effective heat transfer coefficients of heat sinks are compared with those obtained through the compact modeling. Under comparison, the analytical solutions based on the compact modeling are shown to predict the heat transfer characteristics of plate fin heat sink quite well. Comparisons with other studies are also conducted. Using the validated model, the thermal resistances of heat sinks are obtained. The heat transfer characteristics of the heat sink under natural convection are compared with those of the heat sink subjected to forced convection. And finally, thermal optimization of heat sink is performed.
Optimum Heating Control Method to Keep a Given Temperature Rising Speed of a Plate During Rapid Thermal Processing
Authors: Hirasawa Shigeki , Toda Sadanori
Published: August 2009

In rapid thermal processing of semiconductor wafers, it is very important to keep a given temperature rising speed of the wafer during the heating process. We calculated the effect of various heating control methods on the error of the temperature rising speed of the wafer. We calculated the PID control, the control method by correcting with temperature rising speed, the control using a thermal model, the control using a prepared correlation equation, and the combined methods. We found that the combined method with a thermal model and rising speed is a good method to decrease the error of the temperature rising speed. The minimum error of the temperature rising speed at 700°C is less than 0.1°C/s during the temperature rising process of 100°C/s and the monitoring time step of 0.05 s. We calculated the effects of control-delay-time and measuring error of the monitoring temperature on the error of the temperature rising speed.
The Man-Hour Calculation Model for Multi-Stage Manufacturing System Based on Primitive Decomposition and Web Service
Authors: Dong Qiao Ying , Gui Yuan Kun , Kan Shu Lin
Published: August 2009

To solve the problems that basic man-hour data scarcity and avoid the difficulties in establishing man-hour, a man-hour calculation model for multi-stage manufacturing system based on primitive decomposition and Web Service is presented. The model consists of two modules. Aiming at a five-stage manufacturing system contained machine work, punching work, weld work, electrophoresis work and assembly work, the first module analyzed the characteristic of each manufacturing system, proposed the definition and decomposition rule of the primitive operation and founded the man-hour calculation model based on primitive decomposition. In order to use the relevant information about man-hour and provide decision-making and plan-making departments with the distributed manhour data, the second module applied Web Service technique in the enterprise Intranet to achieve the information share in the enterprise. The presented model system simplifies the man-hour establishing process and provides an effective theory model which establishes the man-hour rapidly and accurately. Finally, the products man-hour establishing example in an enterprise shows the feasibility and the good performance of the presented model.
Study of Tool Wear in EDM Using Statistical Design of Experiments
Authors: Agrawal Shyam S. , Agarwal Sanjay
Published: August 2009

The tool wear, while machining a part in electric discharge machining (EDM) process, is of great concern in the researchers in recent years as the accuracy of tool wear directly affects the accuracy of the parts to be produced. The variation in tool wear may occur due to variation in the machining parameters such as current, spark gap, pulse duration, voltage, flushing of dielectric fluid, mode of flushing of dielectrics, taper angle of the tool, etc. This paper represents the effect of current, taper angle of tool and pulse duration on the tool wear during electrical discharge machining of EN-31 tool steel, as this is one of the materials being used increasingly in cold forming rolls, knurling tools, press tools, lathe centers, etc. The experiments have been conducted using “Central Composite Rotatable Design”. Results indicate that the tool wear could be reduced if machining is performed at low current values and low pulse duration and it could be further reduced with increase in the taper angle of tool.
Development of Mathematical Models for Evaluating Child Occupant Impact Dynamics and Intrusions of the Vehicle Structure
Authors: Elmarakbi Ahmed M.
Published: August 2009

Two mathematical models are developed and analyzed in this paper to predict the dynamic response in vehicle crashes. The first model is developed to capture the front-end intrusion of the vehicle structure in frontal collision. The second model is proposed to define the interaction between the child occupant and vehicle passenger compartment and to predict the acceleration injuries during a sudden impulse load. In these mathematical models, the bumper and vehicle body are defined by lumped masses and longitudinal rails of the front-end structure are defined by plastic springs. Moreover, the child occupants are considered as lumped masses, connected to the child seat and vehicle body masses by means of restraint systems. The occupant restraint characteristics of seat belt are represented by stiffness and damping elements. To obtain the dynamic response of the occupant, the equations of motion of the vehicle impact system in both full and offset scenarios are developed and analytically solved using Incremental Harmonic Balance Method (IHBM). The injury criteria, child’s acceleration and vehicle’s font-end deformation, are used to interpret the results. It is demonstrated from the simulations that the dynamic response and injury criteria are easily captured and analyzed. It is also shown that the mathematical models are flexible, useful in optimization studies and it can be used at initial design stage.
Fast-Accurate Model for Performance Prediction of Multistage Impulse Turbine Stages
Authors: Benini Ernesto , Ponza Rita , Ventrucci Irene
Published: August 2009

A one-dimensional model for predicting on/off design performance of impulse turbine stages was developed which accounts for the effects of secondary flows. The well known Craig and Cox loss model was implemented together with unconventional correlations for the estimation of secondary and volumetric effects (those related to leakage flows in labyrinth seals, shrouded rotors and open cavities, balance holes, as well as the volumetric effect due to rotor blockage). These effects were modeled according to off-line CFD simulations of turbine stages and, then, calibrated on experimental data of a number of real multistage impulse turbines. The result is a fast and reasonably accurate model, which can profitably be used for both design and analysis purposes.