bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Automotive Roof Strength and Pretensioner Performance on the Occupant Neck Load
Authors: Thorbole Chandrashekhar K. , Batzer Stephen A. , Renfroe David A.
Published: May 2012

Roof intrusion is a major cause of neck injury to belted occupants during rollover accidents. The correlation of reduced head room with increased injury risk has been demonstrated by the National Highway Traffic Safety Administration (NHTSA) and others such as the Insurance Institute of Highway Safety (IIHS). The current FMVSS 216 standard requires the vehicle roof, when loaded with a platen of prescribed geometry and application vector, to resist 1.5 times the vehicle empty weight before deforming 127mm. This standard was developed to ensure a modest level of safety of the vehicle in rollover. This paper demonstrates the relation between roof intrusions, available head room and belt pretension on occupant neck loads. A validated finite element model of a 2001 Ford Taurus is used to conduct an inverted drop simulation. The vehicle’s roof impacts an ideally rigid surface with 5 deg of roll and 10 deg of pitch. A 95th percentile Hybrid III ATD (Anthropomorphic Test Device) is used to simulate a large occupant. The simulations are conducted both for a production roof and a modified stiffer, stronger roof. The production roof is modified by addition of extra material in the B-pillars and A-pillars to enhance strength. A seatbelt pretensioner is also modeled to demonstrate the effectiveness of belt pretension in attenuating neck loads. This study demonstrates the inadequate performance of the subject production roof in preventing neck injury. The stronger roof in association with the belt pretensioner reduces the magnitude of the neck loads sufficiently to prevent injury. This study indicates that strong, non-deforming roofs along with belt pretension diminishes neck injury.
Electrodeposition in Polymeric Micromolds for the Fabrication of Metallic Microstructures
Authors: Haghdoost Atieh , Pitchumani Ranga
Published: May 2012

Electrodeposition in micromolds is an important step in processes such as LIGA, an acronym from the German words for lithography, electroforming and molding, for fabricating metallic microstructures. This paper investigates electrodeposition in sacrificial polymeric micromolds with a conducting base and plastic features that provide insulating sidewalls for electrodeposition of the desired metallic micropart. Computational models for the governing transport and electrochemical phenomena are used to simulate the evolution of the electro-deposition front. The effects of the applied voltage and micromold geometry are systematically studied for their influence on the resulting electrodeposition rate and the homogeneity of the fabricated microparts. Conditions that lead to desirable process and part quality are derived from the studies.
Real-Time Capacitive Detection of Microdroplets
Authors: Elbuken Caglar , Glawdel Tomasz , Chan Danny , Ren Carolyn L.
Published: May 2012

This paper presents a cost-effective and scalable method for real-time detection of microdroplets in microchannels. Sensing electrodes are manufactured using standard microfabrication techniques. Commercial capacitive sensors are used for detection. The functional and simple hardware ensures portability and yields a signal-to-noise ratio of 4 for electrodes covered with a passivation layer. Experimental results for detection of aqueous droplets in silicone oil are presented.
Evaluation of Mechanical Behaviors of Single-Walled Carbon Nanotubes by Finite Element Analysis
Authors: Lu Xiaoxing , Hu Zhong
Published: May 2012

Based on molecular mechanics, a three-dimensional finite element model for armchair, zigzag and chiral single-walled carbon nanotubes (SWCNTs) has been developed, in which the carbon nanotubes (CNTs), when subjected to load, behave like space-frame structures. The bending stiffness of the graphite layer has been considered. The potentials associated with the atomic interactions within a CNT were evaluated by the strain energies of beam elements which serve as structural substitutions of covalent bonds. The out-of-plane deformation (inversion) of the bonds was distinguished from the in-plane deformation by considering an elliptical cross-section for the beam elements. The elastic moduli of beam elements are determined by using a linkage between molecular and continuum mechanics. A closed form solution of the sectional properties of the beam element was derived analytically and verified through the analysis of rolling a graphite sheet into a carbon nanotube. This method was validated by its application to a graphene model, and Young’s modulus of the model was found, showing agreement with the known values of graphite. Modeling of the elastic deformation of SWCNTs reveals that Young’s moduli and the shear modulus of CNTs vary with the tube diameter and are affected by their helicity. With increasing tube diameter, Young’s moduli of both armchair and zigzag CNTs are increasing monotonically and approaching to the Young’s modulus of graphite, which are in agreement with the existing theoretical and experimental results. The rolling energy per atom was computed by finite element analysis. By comparing mechanical properties with circular cross section models, it is found that the computational results of the proposed elliptical cross-section model are closer to the results from the atomistic computations. The proposed model is valid for problems where the effect of local bending of the graphite layer in a CNT is significant. This research work shows that the proposed finite element model may provide a valuable tool for studying the mechanical behaviors of CNTs and their integration in nano-composites.
A Comparison of 2-D Molecular Tagging Velocimetry (MTV) and Micro Particle Image Velocimetry (µPIV) for Microscale Flows
Authors: Ahmad Farhan , Abdolrazaghi Mona , Nobes David S.
Published: May 2012

A 2-D scanning molecular tagging velocimetry technique is presented. The described MTV technique utilizes a scanning laser system enabling two-dimensional flow velocity measurements. The laser scanning system allows the tagging of molecules seeded in the flow of any desired pattern. This array of small dot markers in the region of interest is visualized using an epi-fluorescent optical imaging system. The scanning system facilitates the convenient maneuvering of the laser beam allowing the tagging of either a single point or a pattern. The laser beam is focused onto a single point leading to a more efficient tagging process. A standard particle tracking velocimetry (PTV) approach is used to resolve the two components of the flow velocity. Results obtained show the capability of the designed system to tag a region in the centre of the field of view. The tagging laser will be moved to any desired location within the field of view to tag the desired region.
Tolerance-Based Layer Setup Optimization for Layered Manufacturing
Authors: Chen Jack Szu-Shen , Feng Hsi-Yung Steve
Published: May 2012

This paper introduces a new tolerance-based method to generate the optimum layer setup required to build layered manufacturing (LM) end-user parts for maximized efficiency. To achieve this, the deviation between the final polished LM part geometry and the original design model are formulated and controlled. Maximized layer thicknesses are then realized through optimization of each layer position with respect to the design and final geometry and maximization of the allowable deviation for each layer, which consequently leads to minimization of the build time. Current LM layer setup methods do not take into account of the final part during layer setup generation, rendering layer thickness selection to operator-deemed-best. Without the ability to predict the final geometry and to optimize the layer setup accordingly, layer thickness selection is often overly conservative, causing more layers than necessary to be used. Since the LM build time increases exponentially with an increase in the number of layers, efficiency is greatly reduced with conservative layer setup. To achieve maximum efficiency, this paper proposes a new method based on error compensation and minimization to solve for the optimum layer setup necessary to allow the resulting final physical part to reliably approximate the design model geometry according to a user specified tolerance limit. Case studies have been performed in order to validate that the proposed method is able to minimize the number of layers for constructing an LM part while controlling the maximum error for tolerance conformance.
Sickle Cell Trait Erythrocytes are Thrice as Stiff as Healthy Erythrocytes
Authors: Maciaszek Jamie L. , Lykotrafitis George
Published: May 2012

Atomic force microscopy (AFM) allows for high-resolution topography studies of biological cells and measurement of their mechanical properties in physiological conditions. In this work, AFM was employed to measure the stiffness of abnormal human red blood cells (RBCs) from patients with the genotype for sickle cell trait. The determined Young’s modulus was compared with that obtained from measurements of erythrocytes from healthy subjects. The results showed that the Young’s modulus of pathological erythrocytes was approximately three times higher than in normal cells. Observed differences indicate the effect of hemoglobin S as well as possible changes in the organization of the cell cytoskeleton associated with the sickle cell trait.
Stress Phase Angle for Non-Invasive Diagnosis of Cardiovascular Diseases
Authors: Al-Rawi M. A. , Al-Jumaily A. M. , Lowe A.
Published: May 2012

In recent cardiovascular studies, the stress phase angle (SPA) has been used as a parameter to identify location for various diseases such as atherosclerosis and aneurysm. This angle represents the phase interaction between the wall shear stress (WSS) and the elastic strain intensity (ESI). It reflects the seriousness of WSS which is a direct measure of these diseases. In this work, a 3D model pulsatile flow in an artery is developed and used to calculate the SPA. Three different models are simulated and the changes in the SPA are observed.
State-of-the-Art and Trends in Through-Silicon Via (TSV) and 3D Integrations
Authors: Lau John H.
Published: May 2012

3D integration consists of 3D IC packaging, 3D IC integration, and 3D Si integration. They are different and in general the TSV (through-silicon via) separates 3D IC packaging from 3D IC integration and 3D Si integration since the latter two use TSV but 3D IC packaging does not. TSV (with a new concept that every chip could have two surfaces with circuits) is the focus of this investigation. State-of-the-art, key differences, trends of these three technologies, and a 3D integration roadmap are presented.
Nano Fracture Chemical Sensor for Explosives Detection
Authors: Yang Se Young , Petruczok Christy , Choi Hyungryul Johnny , Asatekin Ayse , Barbastathis George , Gleason Karen K.
Published: May 2012

Selective detection of explosive compounds is critical for national defense and homeland security. In this paper we describe the fabrication and demonstration of a chemical sensor capable of detecting nitroaromatic explosives in air. The device has the unique features of nano-scale dimensions, simple and inexpensive fabrication, and low power consumption. It consists of a nano-patterned conductive metal line placed on top of a patterned responsive polymer, poly(4-vinylpyridine) (P4VP). Due to polymer-solvent interactions, P4VP swells when it encounters the target analyte, producing a large stress. Detection takes place by monitoring the change in device resistance as the metal nano line deforms or fractures when P4VP swells and transfers mechanical stress. The sensors would be ideal for discreet, wide-scale deployment over large areas. It is also important to note that device sensitivity can be readily enhanced by scaling down the feature size of the metal line or adjusting the material properties of both the metal and polymer. The fabrication process is readily transferrable to a variety of organic and metal materials, improving the versatility of the sensors. The resulting devices may provide new ways to detect security threats and complement existing complex methods to increase the probability of detection and to reduce false alarms. The same approach may also be applicable outside the military/security domain, for example, for pollution monitoring, for factory safety and operational monitoring, or for food quality inspection; all these applications are contingent upon finding the appropriate polymers for the respective analytes.
Genetic Algorithm Based Optimization of Cutting Parameters in Drilling of Composite Materials
Authors: Namazi Hamidreza
Published: May 2012

Composite materials provide distinctive advantages in manufacture of advanced products because of attractive features such as high strength and light weight, but on the other hand machining of composite materials is difficult to carry out due to the anisotropic and non-homogeneous structure of composites and to the high abrasiveness of their reinforcing constituents. This typically results in damage being introduced into the workpiece and in very rapid wear development in the cutting tool. Conventional machining process such as drilling can be applied to composite materials, provided proper tool design and operating conditions are adopted. In this paper, A genetic algorithm (GA) based optimization procedure has been developed to optimize two factors, material removal rate; and delamination factor, using multi-objective function model with a weighted approach for the productivity, and superficial quality. An a posteriori approach was used to obtain a set of optimal solutions. An application sample was developed and its results were analyzed for several different production conditions. Finally, the obtained outcomes were arranged in graphical form and analyzed to make the proper decision for different process preferences. This paper also remarks the advantages of multi-objective optimization approach over the single-objective one.
FEM Stress Analysis of Mechanical Behaviors in Bolted Joints Under External Loadings
Authors: Kuwaki Kengo , Sawa Toshiyuki , Morozumi Yukio , Okumura Masahiko
Published: May 2012

In designing bolted joints, it is necessary to know the stress-changes in bolt loads and the stress distribution at the interfaces between clamped parts when external load is applied to the joints. The ratio of variation of bolt load to external load is called the load factor. The load factors have been studied. However, the load factors for bolted joints using bolt with flange have not been studied. In the present paper the mechanical behaviors of bolted joints in which bolt with flange are used such as the load factor and the contact stress distributions at the bearing surfaces are analyzed using Finite Element Method calculations in the case where the clamped parts are two hollow cylinders. The effects of factor such as flange slope angle on the value of the load factor, the contact stress distribution and permanent set at the bearing surfaces are examined. Variation of permanent set at the bearing surface when the external load is applied has not studied. In the experiments, to examine the load factor for the joints using a bolt/nut with flange, the variations of bolt load under the external loading were measured. The calculated results of the load factor show a fairy good agreement with the measured results. In addition, engineering formula for calculating the spring constant of bolt and nut with flanges are proposed.
Contact Analysis Using Surface Green’s Functions for Isotropic Materials With Surface Stress and Surface Elasticity
Authors: Koguchi Hideo , Nishi Naoki
Published: May 2012

Surface stress and surface elasticity are related to an organization of surface pattern and reconstruction of surface atoms. When the size of material reduces to a nanometer level, a ratio of surface to volume increases. Then, surface stress and surface elasticity influence on mechanical response near surface for an external force on the surface. Stroh formalism is very useful for analyzing the stress and displacement in anisotropic materials. When the Stroh’s formalism is applied to isotropic materials, the eigen matrix derived from equilibrium equation yields a triple root of i (i: imaginary unit), and then an independent eigen vector corresponding to the eigen value can not be determined. In this paper, surface Green function for isotropic materials is derived using Stroh’s formalism. The derived Green function considering neither surface stress nor surface elasticity agrees with the solution of Boussinesq. The surface Green’s function considering surface stress and surface elasticity is used for analyzing the displacement fields in amorphous silicon. It was found that the displacements obtained from the Green’s function were less than those from Boussinesq’s solution. Furthermore, the derived surface Green’s function is applied to a contact analysis for isotropic materials such as amorphous silicon. It is found that an apparent Young’s modulus determined from a force-indentation depth curve increases when surface stress and elasticity is taken into account in the analysis.
Simulated Approach of Fire Risk Analysis With Fuzzy Decision Making Methods: A New Methodology
Authors: Darji V. P. , Rao R. V.
Published: May 2012

This work proposes a way to make existing fire risk analysis methods simpler to use without affecting the accurateness of their results. In general, a fire risk analysis starts with an established burning in a room of origin, i.e., the building location where an ignition occurs. The method then analyses things like the most likely direction that established burning will spread, rate of spread, rate of smoke generation, time people will have to evacuate before untenable conditions are present in the environment, the time the building structure will sustain until collapse, etc. The aim of this paper is to propose the use of the ELECTRE III multicriteria decision aid method, in order to perform the room of origin selection. The advantage of ELECTRE III is that it uses pairwise comparisons between alternative rooms of origin, so as one can select the best one according to predefined preference criteria. Each criterion is weighted to represent its relative importance according to the preference structure of the person performing the selection.
Countermeasure Against Regenerative Chatter in End Milling Operations With Vibration Absorbers
Authors: Nakano Y. , Takahara H.
Published: May 2012

Chatter can result in the poor machined surface, tool wear and reduced product quality. Chatter is classified into the forced vibration and the self-excited vibration in perspective of the generation mechanism. It often happens that the self-excited chatter becomes problem practically because this causes heavy vibration. Regenerative chatter due to regenerative effect is one of the self-excited chatter and generated in the most cutting operations. Therefore, it is very important to quench or avoid regenerative chatter (hereafter, simply called chatter). It is well known that chatter can be avoided by selecting the optimal cutting conditions which are determined by using the stability lobe of chatter. The stability lobe of chatter represents the boundary between stable and unstable cuts as a function of spindle speed and depth of cut. However, it is difficult to predict the stability lobe of chatter perfectly because the prediction accuracy of it depends on the tool geometry, the vibration characteristics of the tool system and the machine tool and the material behavior of the workpiece. In contrast, it is made clear that the stability lobe of chatter has been elevated in the wide range of spindle speed by the vibration absorber in the turning operations. However, it should be noted that none of the previous work has actually applied the vibration absorbers to the rotating tool system in the machining center and examined the effect of the vibration absorbers on chatter in the end milling operations to the best of authors’ knowledge. In this paper, the effect of the vibration absorbers on regenerative chatter generated in the end milling operations is qualitatively evaluated by the stability analysis and the cutting test. It is made clear the relationship between the suppression effect of the vibration absorbers and the tuning parameters of them. It is shown that the greater improvement in the critical axial depth of cut is observed in the wide range of spindle speed by the properly tuned vibration absorbers.
Heat Transfer Analysis of the High-Power LED Lamp With Liquid-Cooled Package
Authors: Jou Rong-Yuan
Published: May 2012

In this study, the technique of immersed LEDs in ambient fluids of air, silicone oil or FC-40, respectively, to cool the LEDs which will generate large amount of heat in operation is investigated by methodologies of experimental measurements and numerical simulations. In experiments, three powers are sequentially input to the LEDs and three fluids, air, silicone oil, and FC-40, respectively, are used to cool the LEDs immersed in these fluids. Temperatures are measured by TCs and IR thermal imager. Detailed temperature and flow fields inside the lamp enclosure are analyzed, and results are compared to experimental measurements. Inclinations of LED lamp in four orientations of 0, 90, 135, 180, respectively, are studied to explore the inclination effects to thermal design of LED lamp. Simulation results found that it is not significant to the LEDs temperature responses. Thermal resistances Rja of the liquid-cooled package of LED lamp are calculated from simulation results, and it is around 13.7 °C/W in this design. In illuminance measurements, measured illuminances show tendency of reciprocal to distance square and proportional to the luminous intensity which is similar to the illuminance principle, and its values are in the sequence of 5W>4W>3W for three kinds of fluids. Basically, illuminances for air, FC-40, and silicone oil fluids are in the sequence of air>FC-40>silicone oil.
An Extended Formulation of Physical Exergy
Authors: Palazzo Pierfrancesco
Published: May 2012

The mechanical aspect of entropy-exergy relationship, together with the thermal aspect usually considered, leads to an extended formulation of physical exergy based on both maximum useful work and maximum useful heat that are the outcome of available energy of a thermodynamic system. This approach suggests that a mechanical entropy can be studied, in addition to the already used thermal entropy, with respect to work interaction due to volume variation. The mechanical entropy is related to energy transfer by means of work and it is complementary to the thermal entropy that accounts energy transfer by means of heat. Furthermore, the paper proposes a definition of exergy based on Carnot cycle that is reconsidered in the case the inverse cycle is adopted and, as a consequence, the concept that work depends on pressure similarly as heat depends on temperature, is pointed out. Then, the logical sequence to get mechanical exergy expression to evaluate work withdrawn from available energy is demonstrated. Based on mechanical exergy expression, the mechanical entropy set forth is deduced in a general form valid for any process. Finally, the extended formulation of physical exergy is proposed, that summarizes the contribution of either heat and work and related thermal exergy as well as mechanical exergy that both result as the outcome from the available energy of the system interacting with an external reference environment (reservoir). The extended formulation contains an additional term that takes into account the volume, and consequently the pressure, that allows to evaluate exergy with respect to the reservoir characterized by constant pressure other than constant temperature. The conclusion is that the extended physical exergy takes into account the equality of pressure, other than equality of temperature, as a further condition of mutual stable equilibrium state between system and reservoir.
Estimation of Incision Patterns Based on Visual Tracking of Surgical Tools in Minimally Invasive Surgery
Authors: Sun Xiaochuan , Payandeh Shahram
Published: May 2012

In minimally invasive surgery, the positions of surgical tools are important in multiple instruments set-up and procedures. Typically, each surgery requires 4–5 incision holes and for each specific procedure, the layout of points defines specific pattern. Taking advantage of this possible one-to-one relationship between a specific procedure in minimally invasive surgery and the incision patterns, such patterns can be utilized in tele-monitoring of trainee during an emulated surgical operation. For example, in performance evaluation of trainee, this procedure would automatically estimate and verify the initial incision pattern to that of the predefined expected template associated with a particular surgical procedure. In this paper, we propose and analyze two models, based on color and shape respectively, to reconstruct the pattern. Both approaches use image information only to reconstruct the incision patterns in three dimensional space. The challenge of monocular endoscopic view is the lack of depth perception which hindered the vision-based tracking of laparoscopic tools. To address the problem, we present a method to determine not only the spatial tip position of the surgical tools, but also their orientation with respect to the camera coordinate frame. Detailed formulation shows that how segmented tool edges and camera field of view localize the 3D orientations of tools. Then, 3D position of the tool tip is reconstructed using either color or edge detection method. Finally, the orientations and the position of tool tips uniquely determine the poses of the tools. From above procedures, geometrical models of cylindrical tools can be constructed in each sequence of mono-camera images. To further use the tracking result in order to localize the incision point, we computed the vectors of the cylindrical tool center lines at multiple poses at number of frames. Extracted incision point is further analyzed as a recognition pattern to map into the patients’ pre-operative incision procedure. Accuracy of 3D tool pose estimation and incision pattern is evaluated in real image sequences with known ground truth.
Approach for a Data-Managmenet-System and a Proceeding-Model for the Development of Adaptronic Systems
Authors: Nattermann Roland , Anderl Reiner
Published: May 2012

Existing proceeding-models for the development of mechatronic systems intend a mostly independent development of single components, like the mechanic structure, the electronics, etc., starting from a combined over-all-model. Following the understanding of adaptronics as an advancement of mechatronics in the LOEWE-Center AdRIA (AdRIA – Adaptronic - Research, Innovation and Application), a clear division of the development is not advisable, because of the high structural integration of adaptronic systems. Because of this, it’s necessary to develop the whole system by using a permanent alignment of values between the single components. This high grade of data transfer and the high number of relations between the components lead to a complexity that can only be handled by the use of a Data-Management-system. An approach for a Data-Management-System for the development of adaptronic systems by the Department of Computer Integrated Design, as part of the LOEWE-Center AdRIA, intends to extend the functionality of existing Product-Data-Management-Systems. The idea is to model the over-all system in the Data-Management-System at first, using the partitioning of the system into the five elements of active structures: excitations, structural components, actuator systems, sensor systems and signal processing. Furthermore the characteristic parameters of single components and the correlations between these parameters are captured. In addition the requirements of the adaptronic systems are captured and deposited in the DataManagement-System (DM-System). An integration-layer is used, to integrate the data and models of the different disciplines to the DM-System and to the generated over-all model, during the development of the adaptronic system. The database of the DM-System contains a standardized over-all-simulation model of the adaptronic system, which uses the same partitioning of the system to the different elements as the overall-system model. The consistent structure of the system-model, simulation-model and integration-layer is used for an automated over-all-simulation of the adaptronic system. Using the automated over-all-simulation changes in the adaptronic-system-behavior can be calculated, when changes in single components become available. Using the deposited requirements, these changes can also be valued. An analysis of existing proceeding-models for the development of mechatronic systems shows, that they are only partly suitable for use in the given approach. Therefore a new proceeding model was developed as an advancement of existing models. The new model shows an equitable solution for the development of adaptronic structures by using Data-Management-Systems.
Sustainable Reference Ontology Development in the Mechanical Engineering Domain
Authors: Goncalves Ricardo Jardim , Sarraipa Joa˜o , Mendonc¸a da Silva Joa˜o
Published: May 2012

Design and manufacturing teams face the challenge of integration and reuse of computational information systems and knowledge. The management of information systems dealing with heterogeneous data and semantics meets the problem of interoperability between software applications, and it has been the basis to research on methodologies for the sustainability of reference ontology development. Ontologies facilitate the computational understanding, communication and seamless interoperability between people and organizations. They allow key concepts and terms relevant to a given domain to be identified and defined in an open and unambiguous way. Therefore, ontologies facilitate the use and exchange of data, information, and knowledge towards intelligent systems interoperability. Tasks on distributed and heterogeneous systems demand support from more than one ontology. Multiple ontologies need to be accessed by the same, but also different systems. The distributed nature of ontology development has led to dissimilar ontologies for the same or overlapping domains. Thus, various parties with different ontologies often do not understand each other. To solve these problems, it is suggested the use of ontology mapping geared for interoperability. This paper proposes a methodology to support the development of a common reference ontology for a group of endeavors sharing a mechanical engineering domain. This methodology enables each organization to keep its own terminology, glossary and ontological structures, providing seamless communication and interaction with the partners, assessed by interoperability checking processes for an overall interoperable level of interacting systems. A use case in mechanical engineering domain is described and the proposed methodology demonstrated.
Experimental and Numerical Analyses of a Pressurized Air Receiver for Solar-Driven Gas Turbines
Authors: Hischier Illias , Leumann Pascal , Steinfeld Aldo
Published: May 2012

A high-temperature pressurized air-based receiver for power generation via solar-driven gas turbines is experimentally and theoretically examined. It consists of an annular reticulate porous ceramic (RPC) foam concentric with an inner cylindrical cavity-receiver exposed to concentrated solar radiation. Absorbed heat is transferred by combined conduction, radiation, and convection to the pressurized air flowing across the RPC. The governing steady-state mass, momentum and energy conservation equations are formulated and solved numerically by coupled Finite Volume and Monte Carlo techniques. Validation is accomplished with experimental results using a 1 kW solar receiver prototype subjected to average solar radiative fluxes in the range 1870–4360 kW m−2. Experimentation was carried out with air and helium as working fluids, heated from ambient temperature up to 1335 K at an absolute operating pressure of 5 bars.
Static Evaluation of Distraction Associated With Axial Rotation of the CerviCore® Intervertebral Disc Prosthesis
Authors: Stascavage Kathryn A. , Brophy Morgan L. , Lisi Alexandra F. , Valdevit Antonio , Errico Thomas
Published: May 2012

Introduction: The spine displays coupled motion. In the cervical spine this may be partly attributed to the oncovertberal joints which act as rails to guide vertebral motion. In axial rotation, a vertical distraction is observed and increases until additional structures are engaged to restrain motion. The purpose of this study was to measure and compare distraction under axial rotation between the intact disc and the CerviCore® Intervertebral Disc prosthesis. Material and Methods: Six caprine functional spinal units (FSUs) were embedded in sleeves with a displacement transducer secured laterally across the disc space. The FSU was placed on the load cell of a materials testing machine and a 100N compressive load applied. Through the use of a rotary table, the inferior body was rotated relative to the superior body to angles of 0, 3, 6, and 9 degrees and distraction recorded at each position. The FSU was then implanted with the CerviCore® Intervertebral Disc prosthesis (without removal of the transducer) and the rotation sequence repeated. Statistical comparisons between the intact and implanted conditions were performed using a repeated measures ANOVA and a Tukey post-hoc test for comparisons between angle configurations. Further comparisons between the intact and implanted conditions at specific angle orientations were performed using a paired t-test. Results: No significant differences were found in axial distraction between the intact and CerviCore® implanted conditions regardless of rotation angle applied (P>0.4 for all). With respect to the effects of rotation angle upon distraction, a significant difference between the 0 versus the 6 and 9 degree conditions (P<0.05 for both) was found for the intact condition. In the case of the CerviCore® implanted condition a significant difference was found between the 0 and 9 degree rotation condition (P<0.05). A linear regression of vertical distraction versus applied rotation resulted in a vertical distraction rate that was not significantly different between the intact and implanted conditions (P>0.08). Discussion: No significant differences were detected for distraction heights at angles of 0, 3, 6, and 9 degrees under intact and implanted conditions. Further, a linear regression of measured distraction versus applied rotation angle indicated that the rate of distraction between intact and implanted conditions was not significantly different. Noteworthy is that in the regression analysis, the confidence bands associated with the implanted device are considerably narrower that those for the intact condition, indicating a more predictable response to applied rotation in the case of the implanted condition.
Exergy and Extended Exergy Cost Assessment of a Commercial Truck
Authors: Cheremnykh Ekaterina , Gori Fabio
Published: May 2012

To gain a clearer understanding of the overall economic and environmental impact of the manufacturing process of a single vehicle, including its operational phase, it is useful to examine the process in a life-cycle perspective and with an exergy approach.. The method of Extended Exergy Accounting (EEA) has already provided reliable results both for the assessment of entire countries and for the analysis of specific industrial sectors. National transportation sectors, generally reputed inefficient, have been the subject of a series of energy and exergy efficiency studies, though so far the phase of vehicle manufacturing was not specifically addressed. The present study is an attempt to quantitatively develop the complex evaluation of the exergy cost of a single vehicle, in particular of a commercial truck produced in the US (for which the available data are extensive and reliable). In the analysis performed in the course of this study, the last version of EEA has been employed, with the latest available data on the allocation coefficients for labour and capital cost factors. Particular attention is given to data selection and their processing. The values of the exergy costs for materials flows, energy inputs and of their equivalents for capital, labour and environment remediation are predicted. The results shows numerically the exergetic costs of economic, labour, material and energy inputs, and emphasize the further research of environmental remediation costs.
Fracture in Taylor Rod Impact Test Specimens
Authors: Gautam Sachin S. , Saxena Ravindra K. , Dixit P. M.
Published: May 2012

High velocity contact-impact problems are of great interest in industries related to aerospace, mechanical and civil engineering. Ductile fracture often occurs in such applications. Taylor rod impact tests are used as experimental and numerical tests for determining the mechanical behaviour of materials subjected to high strain rates. At sufficiently high velocities, a significant plastic deformation leading to fracture is observed. In this paper, ductile fracture in Taylor rod made of AISI1045 steel is simulated using a continuum damage mechanics model. Simulations are performed for the velocity of 250 and 300 m/s. It is observed that, at lower velocities, tensile cracks are observed at the outer edge of the impact surface. On the other hand, at higher velocities, the fracture is observed at the central axis (confined fracture) as well as at the outer edge leading to fragmentation. Both the results are consistent with the experimental results available in the literature.
Comparative Study of Friction Coefficient and Wear in Brake Pads for Disc Brakes
Authors: Caldero´n Juan de Dios , Rojo Alejandro , Pe´rez Carlos , Lo´pez Ricardo , Vilchis David
Published: May 2012

The growing global production and competitiveness of automotive components; as well as, improvements and new developments in terms of designs, materials and standards have provided a wide range of qualities in spare parts products for dealers and their customers. However, sometimes there are not quantitative parameters to compare among manufacturers or dealers do not have the equipment, time and expertise to supply this information. This study presents a comparative test of performance for six different types of brake pads as function of friction coefficient and wear. A test bed composed by an instrumentation system, a braking system and a drive-train system was developed based on standards, then data obtained from measurements of thickness, mass loss, temperature and electric power consumption were used to make calculations and comparisons in order to determine the optimum values. Finally, it was observed that the optimum performance behavior of a brake pad is given as a combination of the optimum values of desirable performance capabilities, like: Heat dissipation, friction coefficient and mass loss.
A Study of Unsteady Mixed Convection in a Lid Driven Flow Inside a Rectangular Cavity
Authors: Akyuzlu K. M. , Hallenbeck K.
Published: May 2012

A numerical study is conducted to identify the unsteady characteristics of momentum and heat transfer in lid-driven cavity flows. The cavity under study is filled with a compressible fluid and is of rectangular shape. The bottom of the cavity is insulated and stationary where as the top of the cavity (the lid) is pulled at constant speed. The vertical walls of the cavity are kept at constant but unequal temperatures. A two-dimensional, mathematical model is adopted to investigate the shear and buoyancy driven circulation patterns inside this rectangular cavity. This physics based mathematical model consists of conservation of mass, momentum (two-dimensional, unsteady Navier-Stokes equations for compressible flows) and energy equations for the enclosed fluid subjected to appropriate boundary and initial conditions. The compressibility of the working fluid is represented by an ideal gas relation and its thermodynamic and transport properties are assumed to be function of temperature. The governing equations are discretized using second order accurate central differencing for spatial derivatives and second order finite differencing (based on Taylor expansion) for the time derivatives. The resulting nonlinear equations are then linearized using Newton’s linearization method. The set of algebraic equations that result from this process are then put into a matrix form and solved using a Coupled Modified Strongly Implicit Procedure (CMSIP) for the unknowns of the problem. Grid independence and time convergence studies were carried out to determine the accuracy of the square mesh adopted for the present study. Two benchmark cases (driven cavity and rectangular channel flows) were studied to verify the accuracy of the CMSIP. Numerical experiments were then carried out to simulate the unsteady development of the shear and buoyancy driven circulation patterns for different Richardson numbers in the range of 0.036<Ri<100 where the Re number is kept less than 2000 to assure laminar flow conditions inside the cavity. Simulations start with a stagnant fluid subjected to a sudden increase in one of the walls temperature. At the same time the upper lid of the cavity is accelerated, instantaneously, to a constant speed. The circulation patterns, temperature contours, vertical and horizontal velocity profiles were generated at different times of the simulation, and wall heat fluxes and Nusselt numbers were calculated for the steady state conditions. Only the results for a square cavity are presented in this paper. These results indicate that the heat transfer rates at the vertical walls of the cavity are enhanced with the decrease in Richardson number.
Experimental Investigation of Natural Convective Heat Transfer From Horizontal, Inclined and Vertical Cylinder With Constant Heat Flux
Authors: Gharehghani A. , Hoseini R. , Salahi M. M.
Published: May 2012

In this study, natural convective heat transfer from cylindrical slender rods with different length and diameters and different angles of inclination (from horizontal to vertical) at constant heat flux condition was measured. For each inclination angle, average natural heat transfer coefficient was obtained. The effects of the angle of inclination and that of the diameter and length of cylinders on heat transfer rates were examined. The angles of 0°, 15°, 30°, 45°, 60°, 75° and 90° were studied. Experimental results show that increasing the diameter of the cylinder, with constant length and the Rayleigh number based on length causes the decrease of the Nusselt number. Increasing the length of the cylinders, with constant diameter and Rayleigh number based on diameter causes the decrease of the Nusselt number. Increasing either the angle of inclination or length decreases the effect of diameter on the heat transfer rate. Experimental results in terms of Nusselt number were correlated as a function of modified Rayleigh number and dimensionless parameters containing diameter, length and orientation angle.
Expectation Management in Product Development
Authors: Fukuda Shuichi
Published: May 2012

It is pointed out in this paper that more attention should be paid to process values. Up to now, we have been focusing our attention only on product value, which is based upon how good functions our final product has. But our customers are active and creative. They are not mere passive consumers. With increasing diversification and with too many products around us, our customers are now looking more for emotional satisfaction. Behavior economics points out the importance of experience value. But they can only discuss about experience at the stage of use. It should be emphasized that we, engineers, can provide exciting experience of creation to our customers, if we get our customers involved in product development. Their involvement can be all the way from design, manufacturing and use to repair. Such experiences will certainly satisfy the highest human needs of self actualization and challenge. If we focus our attention to product value alone, it would be very difficult to let our customers understand quality improvement. But such process values add value very quickly and very remarkably and satisfy our customers to the fullest extent. The problem with process value is that its quality is difficult to evaluate. But if we introduce pattern classification approach, it would be solved very effectively. And further, such an approach reduces time and cost considerably and makes product development very flexible and adaptive to meet the extensively changing and widely varying requirements or expectations from our customers.
Motion Performance Analysis of Double-Slider Two-DOF Parallel Manipulators
Authors: Zhou Hong , Nagapuri Mukesh , Mamidi Sheetal Reddy , Gandham Raj Kumar
Published: May 2012

Double-slider parallel manipulators are closed-loop two-degree-of-freedom linkages. They are preferred to use because of their simplicity plus the common advantages of parallel manipulators such as high stiffness, load-bearing, operation speed and precision positioning. Like other parallel manipulators, the output motion of double-slider parallel manipulators is not as flexible as two-degree-of-freedom serial manipulators. The motion performance analysis plays a crucial role for this type of parallel manipulator to be applied successfully. In this paper, the linkage feasibility conditions are established based on the transmission angle. When feasibility conditions are satisfied, there is no dead position during operation. The workspace is generated by using curve-enveloping theory. The singularity characteristics are analyzed within the workspace. The motion performance index contours within the workspace are produced using the condition number of the manipulator Jacobian matrix. The results of this paper provide guidelines to design this type of parallel manipulator.
Hands-On Graduate Courses in Lean Manufacturing (LM) Emphasizing Green and Total Productive Maintenance (TPM)
Authors: Peter Geoffrey J.
Published: May 2012

The author developed and taught the second hands-on graduate course in a series of three Environmentally Friendly Manufacturing (EFM) courses offered at the Manufacturing and Mechanical Engineering and Technology (MMET) Masters Program at the Oregon Institute of Technology (OIT), Portland Center. Courses in this series include Environmentally Conscious Manufacturing (ECM-1), Lean Manufacturing (LM) emphasizing Green and Total Productive Maintenance (TPM), and Emission Control in Manufacturing (ECM-II). The first two-thirds of the course curriculum consisted of regular classroom lectures, limited homework, two case studies, discussions, videos, and visits to two companies that were implementing or had implemented LM. In addition, a guest lecturer from Washington State Department of Ecology discussed relevant LM and environmental case studies. The final third of the course curriculum consisted of hands-on industry-based case studies. Students gained real-world experience in the manufacturing facilities of the four companies that elected to participate in the pilot project. The LM course, taught from an engineer’s point of view, emphasized the engineer’s role at the initial product design stage, and or manufacturing process design, including building design. This paper describes the course content of the LM curriculum, the innovative methods developed to teach the course, and the methods used to teach LM to graduate students with different undergraduate educational backgrounds including individuals with no prior industrial experience. It discusses three industry-based case studies, company profiles, and the benefits derived by participating companies and graduate students. Curriculum effectiveness was determined at the end of the course in part through students’ and industry participant’s comments. Future publication will describe the contents and case studies of the third ECM II in the EFM course curricula.