bluuebunny/crossref_metadata_2025 huggingface dataset:
The Transformable and Reconfigurable Factory: Strategies, Methods and Case Study
Authors: Wiendahl Hans-Peter , Fiebig Christian , Herna´ndez Roberto
Published: June 2008

The often discussed challenge facing today’s manufacturing companies can be summarized in just a few words: the rapid fulfillment of customers’ requests in agile networks to secure a competitive position in the market. The continual changes occurring in the markets demand greater agility on the part of companies in adjusting to changing circumstances. In the past years, persistent pressures from the market forced enterprises to fundamentally reconsider their production concepts regarding quality and delivery reliability, among other things. The realization of those goals was closely related to a consistent reduction of setup times and to the creation of thorough and easy setting-up procedures. If this idea is transferred to the entrepreneurial level, the necessary continualy modification, transformation and reconfiguration of factories in response to their turbulent environment may be understood as analogous to technical setting-up. Along the value-added chain, components or elements of agility allow for an “easily transformable factory”.
Thorn Implant: A Novel Mechanism for Interamedullary Stem Fixation
Authors: Kasra M. , Grynpass M. D.
Published: June 2008

Existing non-cemented prostheses fixation mechanisms use press-fit techniques to obtain initial stability between bone and implant. For example, the primary fixation of non-cemented total hip stem prosthesis is achieved by carefully impacting the implant to the broached, contoured proximal femur. A successful primary fixation will be followed by the secondary fixation caused by bone ingrowth into the porous surface of implant. However, the primary postoperative fixation of the implants is usually far from ideal [1, 2]. Theoretically, for bone ingrowth to occur, a porous coated implant must be rigidly fixed with close apposition to the bone, without causing excessive stresses and stains at the bone-implant interface. However, this would require the medullar cavity to be prepared to very tight tolerances. In practice, this press fit technique requires interference fit between the prosthesis and the bone, thus creating large stresses and strains. In this case severe impacts for fitting the prosthesis may also fracture the bone. Therefore, it is important that the broaching and contouring of the femur be carried out carefully and exactly. This results in operations being lengthier and more complex. Furthermore, reaming and broaching damage bone vascular system delaying bone formation. The objective of this study was to introduce a novel fixation method, which can achieve immediate initial stability at the operation without having the mentioned problems of contemporary prosthetic designs. In this method, instead of waiting for the bone ingrowth to occur, pins from the inside of a hollow prosthesis stem are driven into the bone making a thorn implant. Therefore, fixation is achieved by so-called metal ingrowth into the bone instead of bone ingrowth into metal.
Evaluation of Lumbar Spine Stabilization Using Anterior Interbody Fusion Cage
Authors: Gao Robert X. , Mitchell Mathew E. , Cowan R. Scott
Published: June 2008

Spinal surgery uses a wide range of instrumentation devices to provide comfort to the patient, stabilize the spine, and enhance the bony healing process after surgery. In order to improve upon the effectiveness of these devices, the interaction between the spine and the implant devices needs to be studied from both medical and engineering perspectives. This paper investigates the effect of an anterior interbody fusion cage on lumbar spine stabilization, by means of numerical analysis using the finite element technique and experimental testing. Specifically, the relative displacement within an intact L4-L5 motion segment has been simulated and measured, under a range of compression, flexion, extension, torsion, and lateral bending loads. Subsequently, the effect of a single anterior lumbar fusion cage implanted into the segment was simulated and experimentally validated, under similar loading conditions. Comparison between the intact and cage-implanted segments indicated varying stabilizing ability of the fusion cage, which is highly dependent upon the cage position and the type of loading.
Effects of Supraspinatus Tear and Repair on Glenohumeral Joint Biomechanics
Authors: McGarry Michelle H. , Bissell Jennifer L. , Yang Bruce Y. , Gupta Ranjan , Lee Thay Q.
Published: June 2008

Rotator cuff tears are common injuries seen by orthopaedic surgeons. Management may vary depending on patient factors, size and location of tear, and severity of symptoms. Treatment for symptomatic rotator cuff tear often includes subacromial decompression, debridement, and/or repair. The objective of this study was to determine the change in glenohumeral joint (GHJ) forces after repair of pathologic supraspinatus tears.
Biomechanical Effects of Failure Modes in Repeated Anterior Inferior Glenohumeral Joint Dislocations
Authors: Lee Thay Q. , Yang Bruce Y. , Tibnoe James E. , McMahon Patrick J.
Published: June 2008

Accurate and precise quantification of the failure modes and repair methods for anterior inferior glenohumeral joint dislocations are very important for effective surgical treatment of the shoulder. The purpose of this study was to quantitatively assess the effects of failure modes and repair strength by measuring the differences in glenohumeral translation and joint forces prior to and following repeated anterior shoulder dislocation and repair.
Performance of a Beowulf Computer System
Authors: Freitas Christopher J.
Published: June 2008

The development of commodity-off-the-shelf computer hardware components has allowed for the trend in high performance computing away from computer-system vendor proprietary hardware. A Beowulf computer system is a high performance computer assembled from commodity-off-the-shelf hardware and uses application programming interface libraries and open source operating systems to create a unified computing environment. In this paper, a Beowulf computer system is described and a performance benchmarking exercise is presented. The simulation is a benchmark problem relevant to hydrocode simulations and specifically simulates the high-speed impact and penetration of a long rod. Through this simulation study and a comparison to similar simulations performed on other computer systems, the price/performance advantage of a Beowulf system is demonstrated.
Visualization of Endothelial Cell Structure During Machine Perfusion Preservation of Livers
Authors: Jain Shailendra , Purohit Saurin , Zhang Jian , Clemens Mark G. , Lee Charles Y.
Published: June 2008

The development of machine perfusion preservation (MPP) of kidney has led to significant improvements and greater success rates in kidney transplantation by providing superior preserved tissue and viable non-heart-beating donor tissue. However, machine perfusion of livers has not been successful in improving preservation. Currently, the major cause of damage associated with MPP of livers remains unclear. Previous studies showed increased vascular resistance and blockages during and after 24hrs MPP but no direct evidence existed. Utilizing a novel two colors fluorophores labeling, an intravital microscopic study was conducted to obtain real time images and confocal microscopy to get detailed images in order to correlate fluorescent-tagged endothelial cells (ECs) with red cell stasis. Fluorescein isothiocynate (FITC) was used to label red blood cells (RBCs) and DiI acetylated low-density lipoprotein (DiI acLDL) was used to mark ECs. Structure of ECs was recorded and assessed during 24hrs MPP with University of Wisconsin (UW) solution at 4°C with a flow rate of 4ml/min. Images recorded from intravital microscopy and confocal microscopy show ECs rounding over a period of 24 hrs and subsequent red blood cells stasis after 24hrs MPP and during rewarming.
Novel Application of Microfluidic Channels in Studying Cell Migration and Reorientation in Response to Direct Current Electric Fields
Authors: Chao P. Grace , Angelini Elsa , Tang Zhongliang , Chang Winston , Bulinski J. Chloe¨ , West Alan C. , Hung Clark T.
Published: June 2008

Electric fields have been shown to induce cell migration (galvanotaxis) and cell shape changes (galvanotropism) in many cell types, such as neural crest cells, embryonic cells, and chondrocytes [1–3]. In this study, a novel microfluidic system was developed to study individual cellular responses to applied electric fields. These microfabricated channels are made from commercially available poly-dimethyl-siloxane (PDMS). This gas permeable, tough, and transparent polymer provides a sterile tissue culture environment and permits visualization of cells using epifluorescence microscopy. In conjunction with the device, a custom computer program was written to quantify the migratory behavior of cells by analyzing changes in position and cell shape. The flexibility of the channel geometry allows for a wider range of chamber resistance and applied currents (achieving a particular field strength) that may permit further study into the underlying mechanisms of electric field directed cell migration and orientation.
Tram-Train: Mixed Use of Rail Corridors
Authors: Tsai Tom
Published: June 2008

One of the new forms of suburban rail services is the joint operation of light and conventional rail equipment on existing rail infrastructure. Beginning with the conversion of the light rail system in Karlsruhe, Germany, several cities in Europe and United States have found the advantage of using light rail vehicles to extend rail service from city center to suburbia via existing conventional railroad irresistible. This seamless mode of transportation offers the most attractive and cost-effective rail system to move a large number of people through the metropolitan area. Using the lessons learned from Europe and America, this paper describes the technical issues involved and its benefits for adoption by transportation planners of this emerging trend.
Simulating the Vibration Environment for Locomotive-Based Friction Control Applications Systems
Authors: Reiff Richard P. , Robeda James , Shust William C.
Published: June 2008

Under the direction of the Association of American Railroads Vehicle/Track System Committee, a laboratory test qualification formula/specification for locomotive-based top-of-rail (TOR) friction modifier application system hardware has been developed. This document describes the development and demonstration process, including measurement of the vibration field environment and an initial test of one TOR component in a laboratory vibration and thermal test. Revenue service onboard locomotive vibration environment was measured continuously during two tests in late-2001 and early-2002. The first test measured responses in a train hauling auto parts while the second measured responses in a train hauling coal. Results of the first simulation suggest that many of the issues experienced from over the road field tests, such as clogging and variable output due to temperatures, were simulated and reproduced in the laboratory simulation.
Experimental Study of Sound Transmission Loss in Electrorheological Liquids
Authors: Szary Marek L. , Noras Maciej
Published: June 2008

Electrorheological (ER) liquids possess the ability to change their physical properties like the apparent viscosity and modulus of elasticity under the influence of an external electric field. They serve successfully in the field of active vibration control—as well as in many other areas. In the Acoustic Laboratory at the College of Engineering, Southern Illinois University in Carbondale, research on the possibility of applying ER liquids to the control of a sound transmission loss (STL) was conducted. The STL was investigated for various kinds of ER suspensions in the frequency range 100 Hz to 2 kHz. An influence of the electric field density on the STL was different for normal and shear stress developed by DC voltage. In both cases the STL decreased with the increasing electric field density. These properties could be potentially useful in sound propagation control applications.
A Matrix Formalism for Fluid-Borne Sound in Pipe Systems
Authors: Gijrath Hans , A˚bom Mats
Published: June 2008

In this paper a general matrix formalism for predicting fluid-borne sound in gas filled pipe systems of arbitrary geometry is presented. Based on the formalism, a code, valid from the low frequency plane wave range up to frequencies where a large number of modes propagate in each pipe, has been developed. The formalism is based on representing the pipe system as an equivalent network of acoustical 2-ports, where each 2-port corresponds to a physical pipe element. Interfaces or branch points between N (≥ 2) pipes in the physical system are represented as node points, which are modelled as multi-ports of order N. For the low frequency range the ports of the equivalent network are defined using travelling pressure wave amplitudes as the state variables. This gives a so-called scattering-matrix formalism that has been described earlier in the literature. For the high frequency multi-mode range it is demonstrated that the same formalism still holds if the state variables are defined via acoustic power. Furthermore, compared to the standard power flow models used today, e.g., the VDI 3733 standard, the suggested matrix formulation can also include the effect of reflections. To enable modelling both of sound generation from fluid machines (fans, compressors,…) and flow generated sound, e.g., from flow separation at constrictions (valves) and bends, both the 2-ports and multi-ports are allowed to be active. In the first version of the code semi-empirical models for flow generated sound from, e.g., valves have been included.
Flow Excited Resonance of a Confined Shallow Cavity in Low Mach Number Flow and Its Control
Authors: Ziada S. , Ng H. , Blake C.
Published: June 2008

Shallow cavities exposed to unbounded, low Mach number flow are generally weak aeroacoustic sources because their acoustic modes are heavily damped. This paper focuses on a cavity mounted on the wall of a duct to investigate the effect of “confinement”, i.e. solid boundaries close to the cavity, on the aeroacoustic response of shallow cavities in low Mach number flow (M < 0.3). It is found that the transverse acoustic modes of the duct-cavity combination are excited by the higher order modes of the cavity shear layer oscillations. The nature of the excitation mechanism as well as the effects of the cavity and duct dimensions are investigated by means of measurements of the amplitude and phase distributions of the acoustic pressure, complemented with flow visualization of the cavity shear layer oscillation. A method to predict the onset of resonance is also suggested. It is also shown that the acoustic resonance is effectively suppressed by a feedback control method, which generates a synthetic jet acting at the cavity upstream corner. The effect of the phase and gain of the controller transfer function is studied in some detail.
Heat Deformation in Optical Measurement of MEMS
Authors: Arai Yasuhiko , Nakagami Tatsuya , Aoyagi Seiji , Mori Atsunobu , Yokozeki Shunsuke
Published: June 2008

The present measurement technology in MEMS fields is not enough to produce a high performance MEMS. The measurement without any transfer of energy is required for the measurement of MEMS. In this measurement, a phenomenon of the heat deformation by the laser beam used in the measurement can be observed in the measured object. In the case of the measurement of MEMS that is very small structure, it is meant that a transfer of energy exists in the measurement using a laser beam. The problems of heat deformation in the optical measurement for MEMS are discussed. It is concluded that the analysis that is given a consideration of the structure of MEMS against the heat deformation is desired in the measurement of MEMS.
Experimental Study on Acoustic Energy Absorbers to Suppress Acoustic Resonance in Tube Bundles of Boiler Plants
Authors: Nishida Eiichi , Miki Masahiro , Sadaoka Noriyuki , Fukano Tohru , Hamakawa Hiromitsu
Published: June 2008

The present paper deals with acoustic resonance in tube bundles which occurred in actual boiler plants. A practical method to suppress the resonant noise is proposed based on scale model tests. In those experiments, besides the transverse modes which are relatively well-known, longitudinal modes which are known to be difficult to suppress, were realized. The relation of both kinds of acoustic modes to vortex shedding frequency was clarified. In the following step, a design method of the acoustic energy absorbers is proposed based on the feedback system stability theory. According to this theory, acoustic energy absorbers were equipped in the duct of the test model, and remarkable increase of the critical flow velocity was confirmed for both types of resonant mode. Based on these results, this method was applied to the actual boiler plants and it was confirmed that the proposed method is the effective countermeasure for both types of acoustic resonant modes.
Flow-Induced Vibrations and Damages of Hydrofoil Systems
Authors: Matveev K. I.
Published: June 2008

Vibrations of hydrofoils on fast ferries are the subject of this paper. Relatively small foil surfaces, already supporting the total ship weight, must sustain unsteady hydrodynamic forces in rough seas and while maneuvering. The resulting hydrofoil oscillations can be estimated for practical purposes, as well as the consequences of such motions. Typical damage induced by vibrations on hydrofoil systems is shown. The eminent example of self-excited oscillations is the hydrofoil singing phenomenon, which is caused by interaction between the foil trailing knife and vortex shedding from the foil trailing edge. Discussion of this effect and means for elimination of the singing phenomenon are presented.
Low Frequency Analysis of the Tracheo-Bronchia
Authors: Al-Jumaily A. M. , Mago N.
Published: June 2008

Theoretical natural frequencies and mode shapes for the tracheo-bronchia of the human respiratory system are determined using the finite element method. Radial modes, which are anticipated to be used for contraction relaxation, are identified. It is anticipated that these values will give the initiation for future development of non-traditional techniques of relieving respiratory system constrictions.
Wafer Scale Modeling and Control for Yield Improvement in Wafer Planarization
Authors: Eamkajornsiri Sutee , Narayanaswami Ranga , Chandra Abhijit
Published: June 2008

Chemical mechanical polishing (CMP) is a planarization process that produces high quality surfaces both locally and globally. It is one of the key process steps during the fabrication of very large scale integrated (VLSI) chips in integrated circuit (IC) manufacturing. CMP consists of a chemical process and a mechanical process being performed together to reduce height variation across a wafer. High and reliable wafer yield, which is dependent upon uniformity of the material removal rate across the entire wafer, is of critical importance in the CMP process. In this paper, the variations in material removal rate (MRR) variation across the wafer are analytically modeled assumimg a rigid wafer and a flexible polishing pad. The wafer pad contact is modeled as the indentation of a rigid indenter on an elastic half-space. Load and curvature control strategies are investigated for improving the wafer yield. The notion of curvature control is entirely new and has not been addressed in the literature. The control strategy is based on minimizing a moment function that represents the wafer curvature and the height of the oxide layer left for material removal. Simulation results indicate that curvature control can improve wafer yield significantly, and is more effective than just the load control.
Non Destructive Diagnosis for Minimum Invasive Access Preparation in Endodontic Treatment
Authors: Dong Janet , Hong Shane Y. , Hasselgren Gunnar
Published: June 2008

Root canal treatment of infected root canals represents a large percentage of business in general dental practice. It is an expensive process and often prone to failure. During root canal treatment, destructive access preparation by removing parts of tooth crown and dentin is usually needed even before a clinician’s inspection and diagnosis. This paper presents a non-destructive method for accessing the internal tooth geometry by building a 3-D tooth model from 2-D radiograph. The geometry of root canals is then formulated into a mathematical model. Based on this mathematical model, the treatment procedures utilizing the dental tools/instruments are planned by a computer aided prescription system, which yields the tool selection and tool path for the root canal preparation by an intelligent micro drilling machine with on-line monitoring. To minimize the removal of healthy tooth crown and dentin, thus protecting the strength of the patient’s infected tooth, an optimization algorithm is utilized for planning the access preparation in the root canal treatment. Although an opening of a tooth crown is still needed so that dental instruments can reach the root canal, the non-destructive 3-D modeling and the optimization of the access preparation in the new approach makes the root canal treatment minimally invasive compared to present techniques.
Micromachined DNA Manipulation Device Using Circular Multi-Electrode
Authors: Moon S. J. , Lee Seung S. , Yun Jae Y. , Nam Hong K. , Chi Yeun T.
Published: June 2008

Microfabricated DNA manipulation devices have a wide range of potential applications. In this paper, we present a new concept for efficient biological reaction and a DNA manipulation device with the reaction chamber, which consists of a center electrode and circular outer electrodes of a reaction unit. We verified the DNA manipulation concept by numerically simulating its operation, and experimenting with the fabricated device. This proposed complex micro reaction or micro analytical systems are generally composed of various components with different functionality within the micro DNA manipulation system. 2cm Square, entirely monolithic device has been fabricated with reaction chamber, circular type electrode, microfabricated heater and sensor. In the suggested reaction system, the charged bio-molecules, DNA, are manipulated by the charge of the electrode in a reaction unit. Controlling the induced dynamic electric field between the center electrode and the outer electrodes, Concentration (+2V) / Repulsion (−2V) / Manipulation (+1V∼−1V) of bio-molecules are enabled at a periphery of electrode. It has no moving parts, physically constructed wall and can be built in a disposable unit of micro devices, which can be fabricated by conventional MEMS technique at low cost. Moreover, we evaluate temperature control unit characteristics for biological analysis such as PCR (Polymerase Chain Reaction), isothermal reaction temperature control. The coefficient of temperature heat resistance and heater temperature characteristic is about 0.0043 and 100°C/sec, respectively.
A Simple Fluid/Structure and Structure/Structure Interaction Problem in Flow-Induced Vibration
Authors: Liu Y. , So R. M. C. , Lau Y. L.
Published: June 2008

It is known that a splitter plate can moderate the vortex formation behind a cylinder, and consequently the vibration behavior of the cylinder and the plate. This paper uses the standard k-ε model and a modified wall function to simulate the flow-induced vibration of a 2D cylinder-plate system in a cross flow. Good agreement between available measurements and calculations is obtained for a single cylinder in a cross flow at Reynolds numbers up to 105. The flow-induced vibration of a cylinder-plate system in a cross flow is attempted using the same numerical method. It is possible to replicate the vibration behavior for the cylinder and the splitter plate, even though quantitative agreement with measurements is not obtained.
A Selectively Anodic Bonded Micropump for Implantable Medical Drug Delivery Systems
Authors: Ridgeway Shane , Song Junho , Cao Li
Published: June 2008

Microelectromechanical Systems (MEMS) fabrication techniques offer a unique solution for implantable medical drug delivery systems. An implantable medical drug delivery system can relieve the pain associated with frequent injections and deliver a localized dosage. An implantable drug delivery system can also avoid contamination and infection better than conventional injection methods (such as intravenous injection). The major advantage of microfabricated drug delivery systems is the possibility of mass production at low cost. A silicon based peristaltically actuated implantable medical drug delivery system consisting of three pumping chambers was microfabricated and tested. The unique features of this microfabricated drug delivery system include the design of a selectively anodic bonded micropump. The selectively anodic bonded Pyrex glass wafer was used to seal the pump chambers and allow for a view of fluid movement. Chromium was used as a selective bonding material. A 20 nm thick chromium film deposited on the top surface of the silicon valves successfully prevented bonding between the valve and the glass wafer. The pump operates with a normally closed valve which consists of a silicon mesa located at the center of each chamber. This mesa makes intimate contact with the glass wafer. Three 180 μm deep and 12 mm diameter circular chambers were etched into the top surface of the silicon wafer using deep reactive ion etching (DRIE) and connected by two 1 mm wide channels. Directly opposite the chambers, three 12 mm diameter circular features were etched 320 μm deep using DRIE to create a 50 μm thick silicon membrane and provide an attachment point for piezoelectric actuating disks. The piezoelectric disks were applied using a conductive silver epoxy. A positive potential was applied to the gold layer that was e-beam deposited on the substrate, with the negative terminal applied to each individual actuator. The three pump chambers were actuated in a peristaltic motion with driving frequencies ranging from 0.5 to 4 Hz and actuation voltages ranging from 10–130 V. The design goal of 10 μL/min was met at driving frequencies of 2 and 4 Hz where the maximum flowrate was 10.1 and 11.4 μL/min for the 2 and 4 Hz actuation frequencies respectively at an actuation voltage of 130 V. The maximum pressure achieved by the pump was 35.8 mmH20 for the 2 and 4 Hz actuation frequencies at an actuation voltage of 130 V.
Rapid Separation and Manipulation of DNA by a Ratcheting Electrophoresis Microchip (REM)
Authors: Dunphy Katherine , Milanovic Veljko , Andrews Samantha , Ohara Taku , Majumdar Arun
Published: June 2008

The Ratcheting Electrophoresis Microchip (REM) is a microfluidic device for electrophoretic separation of biomolecules such as DNA and proteins. By using thousands of electrodes along the length of a microchannel, the REM separates molecules using low applied voltages (∼1 V) in short times (< 1 minute). This paper describes the microfabriation of the REM and initial testing results. Parallel arrays of platinum electrodes are fabricated on a silicon chip with a pitch of 10 μm. Two types of channels are fabricated: silicon nitride channels fabricated on the chip and poly(dimelthylsiloxane) (PDMS) channels fabricated separately and attached to the chip. Initial testing shows partial success with the PDMS channels and promis ing results for the silicon nitride channels.
Stamping Die Strip Optimization for Paired Parts
Authors: Vamanu Vasile , Nye T. J.
Published: June 2008

In stamping, operating costs are dominated by raw material costs, which can typically reach 75% of total costs in a stamping facility. In this paper, a new algorithm is described that determines stamping strip layouts for pairs of parts such that the layout optimizes material utilization efficiency to any desired accuracy. This algorithm predicts the jointly-optimal blank orientation on the strip, relative positions of the paired blanks and the optimum width for the strip. Examples are given for nesting pairs of the same parts together, and for pairs of different parts nested together. This algorithm is ideally suited for incorporation into die design CAE systems.
Reduction of Flow-Induced Vibration Using Parametric Excitation
Authors: Tanaka Tomotsugu , Takano Koetsu , Fujiwara Hiroyuki , Matsushita Osami
Published: June 2008

Vibration of structures, such as suspension bridges, skyscrapers and high rises, sometimes cause people to feel anxious. These vibrations are usually induced by the fluid flow, especially vortex shedding and they grow into self-excited vibrations, which are normally accompanied by the extremely large vibration amplitude. In order to solve these vibration problems, many researchers have reported the effectiveness of vibration control methods and most of the methods are very practical for the actual structure. These control methods usually consist of feedback control systems for the active control and some kinds of damper for the passive control. This paper deals with one control method, which is using the parametric excitation. The efficiencies of this method for the self-excited vibration have already been analytically examined by Tondl. However, it is not confirmed experimentally, and it is necessary to discuss the possibility of realization and application for the actual system. In this study, our experiment confirms the effectiveness of this control method. For this purpose, an experimental apparatus, which expressed a two degrees of freedom system and consisted of an electromagnetic actuator, a steel beam and two masses, were prepared. A digital signal processor was used for the realization of the parametric excitation control. During the experiments, we confirmed the effectiveness of the control procedure and accuracy of the theoretical results. In addition, the relationships between the ratio of the two masses and the ratio of the natural and the parametric excitation frequency, which are required for the effective control, were cleared. According to this study, the quenching of self-excited vibration by using the parametric excitation is realized within the very narrow band of frequency and the mass ratio should be small.
A Polyacrylamide Gel With Reversible DNA Crosslinks
Authors: Lin David C. , Yurke Bernard , Langrana Noshir A. , Mills Allen P.
Published: June 2008

A broad range of compositions, properties, and forms has made polymers the most diverse class of biomaterials available [1]. Among polymers, hydrogels have the unique capacity for preserving their shape and mechanical strength even while imbibing water and ions. Biological hydrogels include components found in muscle, tendons, cartilage, intestines, and blood [2].
Adaptive Feedrate Scheduling and Material Engagement Analysis for High Performance Machining
Authors: Kloypayan Jirawan , Lee Yuan-Shin
Published: June 2008

This paper presents a technique of feedrate scheduling by analyzing the material removal volume when a tool moves in linear, circular, or parametric curved motions. Tool motions of different types of endmilling cutters are considered in this study. By studying the relationship between the cutter geometry and the tool motion, the material removal rates of different cutters are analyzed. The adaptive feedrate scheduling can be determined to maintain a constant cutting load. The technique developed in this research can be used for tool path generation in CAD/CAM systems for 2.5D NC machining.
The Effects of Structural and Servo Modes in Titanium Machining
Authors: Smith K. Scott , Lamy Bethany A.
Published: June 2008

This paper shows that in titanium machining the metal removal rate may be limited by factors including the dynamic characteristics of the frame of the machine and the servo. Self-excited vibrations related to these components led to poor cutting performance and tool breakage. Measurements of the acceleration were made during a number of cuts. In combination with impact tests, these measurements were used to identify the natural frequencies and mode shapes associated with the structural modes. These measurements ultimately led to adjustment of parameters in the control loop (to modify the servo dynamics), to special tool selection (to disturb the regeneration), and to the choice of stable cutting speeds (to take advantage of the stability lobes). The resulting cutting conditions significantly improved the metal removal rate. The nature of current titanium machining makes the structural modes particularly problematic, and it is important to measure and consider them during process planning.
A Surface Micromachined Spiral-Channel Viscous Pump
Authors: Kilani Mohammad I. , Galambos Paul C. , Haik Yousef S. , Chen Ching-Jen
Published: June 2008

The paper introduces a new viscous pump, called the spiral pump, which targets surface micromachining, and outlines its implementation in five levels of polysilicon using Sandia’s Ultraplanar Multilevel MEMS Technology (SUMMiT). For the purpose of analyzing the flow field in the pump, the spiral channel is approximated as an equivalent straight channel. After demonstrating the validity of this approximation for typical design, the paper presents a lubrication solution of the flow field in the channel, which is used to relate the flow rate, torque and power to rotation rate and pressure head. Experimental flow rate versus pressure data obtained from a scaled up spiral pump prototype are compared with analytical predictions, highlighting needed research efforts in modeling and analysis of the spiral pump.
Experimental Study of the Cold Restart of a Pipeline Filled With a Gelled Waxy Oil
Authors: Miles Scott A. , Wheeler G. Egan , Hall John W.
Published: June 2008

Experiments were conducted on the flow field start up behavior of a gelled waxy oil in a pipeline. A simulant fluid was used to mimic the low temperature rheology of crude oil. The break down of the gelled simulant fluid was studied during different startup conditions. It is shown that the “failure mode,” or manner and location in which the gelled simulant fluid breaks down, is closely related to both the temperature of the gel and the cooling time prior to pressurization. Flow visualizations indicate that for higher temperatures, and long cooling times, exists a weaker gel strength and failure occurs near the centerline of the pipe. Lower temperatures and long cooling times result in the breakdown of the gel at the pipe wall. Shorter cooling times result in a weak centerline gel strength, and results in gel failure near the centerline of the pipe. Pressure and temperature data were acquired at seven locations along the length of the test section, and these data were correlated to the velocity field, measured using Particle Image Velocimetry. Combined with rheology measurements, these data, allowed for shear stress estimates to be made. For the parameter ranges explored, the results exhibit three different failure modes, each associated with a different set of initial conditions. A critical temperature existed above which one failure mode was encountered and below which another failure mode was found. A third failure mode was associated with a cross-section that did not have a uniform radial temperature profile.
A Unified Model for Shear Driven Gas Micro Flows
Authors: Bahukudumbi P. , Beskok Ali
Published: June 2008

We analyze steady one-dimensional plane Couette flows in the entire Knudsen regime with the objective of modelling shear-driven rarefied gas flows encountered in various micro electromechanical system (MEMS) applications. In particular, we develop a unified empirical model, which includes analytical expressions for the velocity distribution and shear stress. The new model is validated by comparisons with the linearized Boltzmann solutions available in the literature, as well as hard-sphere direct simulation Monte Carlo (DSMC) results. Overall, the new model predicts the velocity distribution and shear stress with good accuracy for a wide range of Knudsen numbers (0 < Kn ≤ 12), and it is valid for incompressible or low subsonic compressible flows (Ma ≤ 0.3).
A High Shear Rate Sliding Plate Rheometer for Nonlinear Viscoelasticity
Authors: Sodeifian Gholamhossein , Haghtalab Ali , Abdollah Amir
Published: June 2008

In most of polymer processings, such as injection molding and extrusion, materials are subjected to high deformations. In order to study nonlinear viscoelastic properties, it is necessary to have an instrument to generate high shear rates. A new sliding plate rheometer incorporating shear stress transducer has been developed. This rheometer has been equipped with a robust servohydraulic linear actuator which can generate shear rates and frequencies up to 900 (1/S) and 500 (Hz) respectively, compared with maximum 500 (1/S) and 100 (Hz), used in latest researches. Using this system, a wider range of nonlinear viscoelasticity can be investigated.
Dynamic Analysis of Airflow in Air-Jet Filling Insertion: Part I — Air Pressure Measurements
Authors: Bakhtiyarov Sayavur I. , Adanur Sabit , Turel Tacibaht
Published: June 2008

Air-jet filling insertion is the most used techniques in the textile industry. In this process the air flow provides the necessary propelling force to the yarn. Dynamic analysis of air flow in this process was studied experimentally in this work. In Part I we present the results of experimental measurements of pressure losses both in the tube-guided and in the profiled reed simulators.
Computing Micro Synthetic Jet in Slip Regime With Moving Membrane
Authors: Aslan A. Rustem , Baysal Oktay , Edis Firat O.
Published: June 2008

A Navier-Stokes (NS) solver for moving and deforming meshes has been modified to investigate numerically the diaphragm-driven flow in and out of two synthetic jet cavity geometries. The piezoelectric-driven diaphragm of the cavity is modeled in a realistic manner as a moving boundary to accurately compute the flow inside the jet cavity. The primary focus of the present paper is to describe the effect of cavity geometry and the wall slip, resulting from the relatively larger Kn number flows associated with micro sized geometries, on the exit jet velocity magnitude. Compressible flow simulations are required for rarefied flows to accurately predict the pressure field. The present computations for the quiescent external flow condition reveal that cavity geometry and the wall slip has an increasing effect on the magnitude of the average jet exit velocity as well as vortex shedding from the orifice.
Fabrication and Testing of a MEMS Low-Flow Meter
Authors: Sheppard Jason , Clendenin Jason , Chiu Edward , Tung Steve
Published: June 2008

A compact MEMS flowmeter was fabricated and tested for small gas flow rates from 0.5 to 10 sccm. The flowmeter was fabricated by integrating a silicon chip consisting of three surface-micromachined sensor clusters with a 60μm tall, 1.25 mm wide, and 10 mm long flow channel. Each sensor cluster in the chip consists of a pressure sensor, a surface shear stress sensor, and a temperature sensor. As gas flows through the channel, the volumetric flow rate is determined by measuring either the pressure drop in the flow direction or the local surface shear stress. The temperature sensors in the clusters mainly function as a reference for temperature compensating of the thermally based shear stress sensors. The flowmeter was calibrated in an open-loop pipe-flow facility using nitrogen as the gas medium. Based on the test results, it is clear that the pressure sensors, while capable of handling high flow rates, do not have the necessary precision level for small flow measurements. By comparison, the shear stress sensors, after proper temperature compensation, provide consistent and repeatable measurements for small flow rates. Additionally, the voltage output of the shear stress sensors also follows the 1/3 power trend, previously predicted for macro flow situations, in the small flow range tested.
Process Modeling of Shape Rolling for Aerospace Industry
Authors: Ranatunga Vipul , Gunasekera Jay S.
Published: June 2008

Shape rolling of seamless rings constitutes an efficient manufacturing process offering excellent material yield, energy conservation, and component production, which require a minimum of subsequent machining operations. An increasing number of rings are being produced from high temperature Titanium and Nickel based super alloy materials for gas turbine engine parts such as vane and fan casings, exhaust casings, turbine shrouds, and combustion liners. With the increasing cost of super alloy raw materials and growing demand for cost-competitive parts, the importance of ring rolling to contoured shape becomes an increasingly important factor. This paper describes a new process modeling technique based on Upper Bound Elemental Technique (UBET) for shape rolling of super alloys. This tool provides a new design paradigm for an industry relying to heavily on designer experience and cut-and-try methods. As a rapid software tool to aid designers in developing ring-rolling process schedules thereby helping in reducing the design and analysis cycle time, the potential to capture the unique 3-D flow situation experienced in shape rolling of seamless rings is being explored. Numerical results have been compared with data available for high temperature alloys such as IN718 and Ti-6Al-4V.
Estimates Between Lagrangian and Eulerian Integral Scales: Theoretical, Experimental and Numerical Aspects
Authors: Huilier Daniel G. F.
Published: June 2008

The purpose of the present communication is to summarize the state-of-the art knowledge of the existing relationships between Eulerian and Lagrangian statistics in the literature. It will focus on integral scales, especially the classical Eulerian scales (such as those classically obtained from a fixed hot-wire or LDA control volume), the interesting moving Eulerian time scale (that obtained by a sensor which would move with the mean velocity) and the Lagrangian integral scale, most important for Lagrangian turbulent diffusion and dispersion simulations.
Cutting Computation Time and Mastering the Underlying Science of Introductory Thermodynamics
Authors: Lopez Guido W.
Published: June 2008

Traditionally, the teaching and learning of introductory undergraduate Thermodynamics in Mechanical Engineering programs stressed the manipulation of formulas and the use of property tables. At present, the use of computer-based instruction is becoming more common in the classroom and it is proving to be a valuable tool for enhancing the educational experience of students. In teaching Thermodynamics, for example, much of the tedious manipulative and computational work encountered while solving problems can now be effectively and quickly executed by computer software. This approach leaves ample time for instructors to emphasize concepts and principles instead of procedures, and to foster an environment that helps students to master the underlying science of the discipline while minimizing computational burden. A comparative study between teaching introductory Thermodynamics using a traditional approach versus using the software EES (acronym for Engineering Equation Solver) as a computational tool is presented in this paper. A statistical comparison of academic performance in introductory Thermodynamics between two groups of engineering students of comparable academic level and capability but enrolled in different schools is also part of this study. Qualitative and quantitative results suggest that students can achieve a clearer understanding of concepts, definitions and principles of introductory Thermodynamics when using computer software as a tool in their learning process.
Computer Aided Bearing Design and Analysis
Authors: Vavrek Edward M.
Published: June 2008

I have written a program using visual basic called Bearing Design. Students in a machine elements course will use the program to size and select bearings. The program is written to aid students in the understanding of bearing design. The program is part of a series of programs used to assist the students in learning how to design and select machine components. Some of the other programs used are Designing Spur Gears and Sizing Belt Drives Components.
Modernization of the Mechanical/Manufacturing Engineering Laboratories: Upgrading Educational CIM Cells Involving Students and Faculty
Authors: Hossieny Morteza Sadat , Khan Hamid
Published: June 2008

This paper reports the process of upgrade and enhancement of the Educational CIM Cell at Northern Kentucky University (NKU). The upgrade is part of the laboratory experiments in the Automated Manufacturing Systems Course at NKU. The goal of this paper is to increase students’ practical experience, upgrade the equipments in house, save cost, and reduce the technical dependency on an outside company. In this project Allen-Bradley SLC 100 PLC and Allen-Bradley SLC 150 will be upgraded with a new Allen-Bradley PLC and Panelview operator interface. Comprehensive effort are made to incorporate what has been learned in the MET program to design, manufacture a part, and use robotics and programmed interface for placement onto a conveyor. After the part is placed on the conveyor it will be transferred to a location where the part will be accepted or rejected. Personal computers will be interfaced for simulation, and to actual hardware for control and automation of typical manufacturing operations and industrial processes. This concept of an integrated laboratory system will allow expanded coverage of traditional controls topics and permit introduction of appropriately advanced control techniques including adaptive control for machining operations. This method of modernizing is shown to be more effective than modernizing by a turnkey upgrade of the laboratory Computer Integrated Manufacturing (CIM) facilities.
Effect of Length on the Instability of Hanging Pipes
Authors: Doare´ Olivier , de Langre Emmanuel
Published: June 2008

The flutter instability of a hanging fluid-conveying pipe is investigated, as its length is increased. Experiments show that there exists a critical length above which the flow velocity necessary to cause flutter becomes independent of the pipe length. The fluid-structure interaction is thus modelled by following the work of Bourrie`res and of Pai¨doussis. Computations using a standard Galerkin method confirm this evolution. A short pipe model is then considered, where gravity plays a negligible role. Transition between this short length model and the asymptotic situation is found to occur where a local stability criterion is satisfied at the upstream end of the pipe. For longer pipes, a model is proposed where the zone of stable waves is totally disregarded. Comparison of these models with experiments and computations show a good agreement over all ranges of mass ratios between the flowing fluid and the pipe.
Pumping by Beating on a Tube
Authors: Auerbach David , Moser Maximilian , Kenner Thomas
Published: June 2008

Beating on an open elastic tube which has been bent into a U-form leads to a pumping effect, probably related to the so called Liebau effect. This pumping can be appreciable, a water head of 50cm or more being easily manually attainable. For low frequencies no pumping occurs. For higher frequencies pumping may take place in both directions, dependent on the beating, tube and fluid characteristics. The pumping effect generally reaches a maximum for percussion positions distant from the mid-point between the ends of the tube and is generally in the direction of the longer length of the tube. The dynamics of this system in these experiments calls certain of the many prevalent theories on this mechanism into question.