bluuebunny/crossref_metadata_2025 huggingface dataset:
Detailed Investigation of Capacitive Micromachined Ultrasound Transducer Design Space for Optimal Operation
Authors: Onen Onursal , Guldiken Rasim
Published: August 2012

This paper presents our detailed design studies on capacitive micromachined ultrasound transducers (CMUTs) via finite element models developed in ANSYS 12. In this study, we will discuss our experimentally verified coupled field finite element simulations for operation frequency and bandwidth. The effects of device geometry, type of coupling media, material selection and properties are investigated for the frequency response, and bandwidth using an analytical approach. A commercial design of experiment software, Minitab is utilized for sample runs for obtaining response curves. The design principles for CMUTs are given in detail for effective and quick design. The design guidelines illustrate that, the frequency response is a strong function of transducer geometry, material selection and coupling media.
Notched Strength and Fractures Behavior of Chopped Glass Mat Reinforced Unsaturated Plastics
Authors: Nishida Ryuiti , Yu Ying , Yang Yuqiu , Hamada Hiroyuki
Published: August 2012

Glass chopped fiber mats have been used as traditional reinforcements for fiber reinforced plastics. However, the literature is found limited even it has a long history. However short fiber mats is considered to be suitable reinforcement configuration for natural fiber or filled composites because the natural fiber is inherently short fiber. Various fiber textile technologies are available to be used to fabricate the fiber mats structure, for example needle punching process. Therefore the relation between different textile manufacturing techniques (the fiber mat structure) and the composites properties is considered necessary to be should be fully understood. Chopped glass mat reinforced composite was used as experimental materials and the fracture behavior of the specimens with drill-hole was investigated. Acoustic emission (AE) measurement was carried out by using Dual AE measurement system with both 140 KHz and 1 MHz sensors to understand the fiber and matrix fracture behaviors simultaneously. Also the characteristic distance was calculated experimentally and was compared theoretically with the values obtained from finite element stress analysis. It is found that the notched strength decrease by drilling a hole in the center. While regarding to the effect of w/d ratio i.e. the ratio of width to the diameter of the drill-hole, w/d of 3 specimens seems to have relative higher notched strength as compared to 2 or 5 w/d specimens. During the tensile test AE signals which detected by both 140 kHz and 1MHz are found to be generated almost at the same time. Additionally, the white area before the final broken seems to relative to the characteristic distance calculated by finite element stress analysis.
The Effect of Nano-Structured Surfaces on Droplet Impingement Heat Transfer
Authors: Rosengarten Gary , Tetuko Anggito , Li Ka Kit , Wu Alex , Lamb Robert
Published: August 2012

Droplet impingement is a fundamental process for many applications particularly those involving heat transfer. While there has been considerable work over many years on understanding the flow and heat transfer processes, we have only recently been able to fabricate controllable nanostructured surfaces. Surface structure can have a massive impact on the droplet impact process dynamics and the associated convective heat transfer from the liquid droplet to the surface. In this paper we examine the impact dynamics and heat transfer using simultaneous high speed thermal imaging of the liquid from below, and high speed video camera images from the side for different surfaces, ranging from hydrophilic to superhydrophobic. In this way we characterize the heat transfer process as a function of the droplet dynamics and the surface properties. We show that the heat transfer rate is primarily affected by the contact line dynamics and the wetted area. Due to the superhydrophobic roughness scale being relatively small, the interface resistance offered by the trapped air has only a small effect on the heat transfer rate, and only in the inertia dominated region before maximum spreading diameter. Finally we show that the overall cooling effectiveness of as single impinging droplet is very dependent on the surface properties with hydrophilic surfaces offering the highest cooling effectiveness.
Analysis of Thermal-Mechanical Coupling and Thermal Wave Penetration Depth for Thermo-Acoustic Emission
Authors: Hu Hanping , Wang Yandong
Published: August 2012

In this work, some analyses of a generalized expression of the thermo-acoustic (TA) emission are carried out. The results of the study clearly show that a wideband flat amplitude-frequency response mostly in ultrasonic region exists for TA emission from not only porous silicon (PS) but any solid, and the fully thermal-mechanical coupling and effective thermal-wave penetration depth should be taken into account for the calculation of its signal magnitude and frequency range. Problems occurring in Nature paper on the thermally induced ultrasonic emission from PS are also pointed out and discussed. Besides, the performance evaluation techniques for both TA material and its backing are presented.
Towards Integrated Design of Plant/Controller With Application in Mechatronics Systems
Authors: Kianfar Roozbeh , Fredriksson Jonas
Published: August 2012

In this paper, a method is proposed for integrated design of mechatronics systems. The integrated design problem is formulated as a semi-definite programming optimization problem. However, this is an infinite dimensional convex optimization problem, which is hard to solve. In this paper, it is shown that a vertex enumeration method can be used to transform the infinite dimensional optimization problem into a finite dimensional problem, which under the assumptions that the state space matrices are affine function of structural variables and that the structural variables belong to a polytope, can be solved efficiently. To show the effectiveness of the method, the method is applied to a mechatronics system.
Modeling of Laminar Viscous Flow in a Semi-Porous Channel Under Uniform Magnetic Field
Authors: Abdel-Rahim Yousef M. , Al-Sood Maher M. Abou , Ahmed Mahmoud A.
Published: August 2012

Laminar flow in porous channels or tubes has received a great attention in recent years due to its various applications. These applications include blood filtration in artificial kidney, blood flow in capillaries and oxygenations, transpiration, cooling of turbine blades, lubrication of ceramic machine parts, food processing, electronics cooling, gaseous diffusion, the extraction of geothermal energy, and nuclear reactor cooling systems. The present work, proposes the Galerkin method to solve the two dimensional electrically conducting flow in a semiporous channel under uniform magnetic field as governed by dimensionless: Hartman number (Ha), and Reynolds number (Re). The numerical results predict the flow field characteristics over wide ranges of Ha, and Re. These results are compared with other available analytical and numerical results at different values of Ha, and Re. Detailed results are presented and discussed.
On the Dispersion of the Axisymmetric Longitudinal Waves in the Pre-Strained Bi-Layered Hollow Cylinder Under Imperfect Contact Between the Layers
Authors: Akbarov S. D. , Ipek C.
Published: August 2012

This paper studies the influence of the shear-spring type imperfectness of the interface conditions on the dispersion of the axisymmetric longitudinal waves in the pre-strained bi-layered hollow cylinder made from hyper-elastic compressible materials. The investigations are made within the framework of the piecewise homogeneous body model by utilizing the 3D linearized theory of elastic waves in initially stressed bodies. The elasticity relations of the layers’ materials are given through the harmonic potential. The shear spring type imperfectness of the interface conditions is considered and the degree of this imperfectness is estimated by the shear-spring parameter. Numerical results on the influence of the problem parameters, especially, of the shear-spring parameter on the behavior of the dispersion curves related to the fundamental mode are presented and discussed. In particular, it is established that as a result of the aforementioned imperfectness of the interface conditions, the dispersion curve related to the fundamental mode has two branches: the first disappears, but the second approaches the dispersion curve obtained for the perfect interface case by decreasing the shear-spring parameter.
Reduction of the Impact-Induced Experimental Dynamics of a Foam-Filled Thin-Walled Aluminum Beam Interacting With Water
Authors: Georgiou Ioannis T.
Published: August 2012

We applied a novel sensing and data processing technique to analyze the water-interaction dynamics of a thin-walled aluminum beam filled with micro-structured material. The spatial impulse response is sensed at three spatial points in the form of ensembles of collocated acceleration signals. Processed by the powerful POD Transforms, the modal-like decomposition of collocated acceleration signals provides interesting insight on the nature of impulse-induced vibrations of this complex structure-water system. When not interacting with water, the point impulse excited structure vibrates in a dominant POD mode with energy-transfer wave form characteristics. When interacting with water, the point impulse excited structure vibrates in two POD modes. One POD mode is vibration while the other one is rigid-flexible body motion. The POD modes capture characteristics of interactions between flexible body (vibration-wave) and rigid body motions. This modal identification technique is potentially useful for reduced model identification and parameter estimation of hard to model complex structural-fluid interacting systems encountered in aerospace and ocean environments.
Enhanced Solar Energy Harvest for Power Generation From Brayton Cycle
Authors: Neber Matthew , Lee Hohyun
Published: August 2012

A scalable and modular solar thermal dish-Brayton system is proposed in response to growing demand for renewable energy and distributed power generation. Existing dish systems require large areas to achieve sufficient conversion efficiency for the cost of the system. Also, the conversion efficiencies are limited by the materials and manufacturing processes. This paper proposes a low cost, high efficiency solar absorber as the core of a dish-Brayton system with the capability to achieve much higher operating temperatures than current absorbers. A simple cylindrical part, forming a black body cavity, is fabricated from silicon carbide for high absorptivity at a low fabrication cost. The manufacturing process consists of a simple casting and sintering procedure, which is a common way of creating ceramic parts. Another cylindrical shell is fabricated to cover the outer surface of the black body cavity, creating a channel for air to pass through. The high thermal conductivity of the silicon carbide ensures the efficient heat transfer between the solar absorber and the air. The entire solar energy absorber is designed to heat air up to 1500 K, which would improve energy conversion efficiency of concentrated solar power generation based on 1270 K by 20%. Analysis and test results on a scaled device are presented.
A Microfabricated Enzyme-Free Glucose Fuel Cell for Implantable Devices
Authors: Oncescu Vlad , Erickson David
Published: August 2012

In the past decade the scientific community has showed considerable interest in the development of implantable medical devices. Such devices have low power requirements and can potentially be operated through fuel cells using reactants present in the body such as glucose and oxygen instead of non-rechargeable lithium batteries. In this paper we present a thin, enzyme-free fuel cell with high current density and good stability at a current density of 10μA cm−2. The fuel cell uses a stacked electrode design in order to achieve glucose and oxygen separation. In addition, it uses a porous carbon paper support for the anodic catalyst layer which reduces the amount of platinum or other noble metal catalysts required for fabricating high surface area electrodes with good reactivity. The peak power output of the fuel cell is approximately 2μW cm−2 and has a sustainable power density of 1.5μW cm−2 at 10μA cm−2. An analysis on the effects of electrode thickness and inter electrode gap on the maximum power output of the fuel cell is also performed.
Nonlinear Vibration Analysis of MEMS Micro-Beam Structure Acting by Multi-Couplings Factors
Authors: Huang Dengwei , Li Shoujian , Chen Changping , Dai Liming
Published: August 2012

In this paper, the nonlinear vibration characteristics of the micro-beam structure acting by multi-couplings factors are investigated. Taking the nonlinear air damping force, alternating voltage excitation as well as the geometric nonlinearity of the micro-beam into account, the nonlinear vibration governing equations of the micro-beam are derived on the basis of the Euler-Bernoulli beam theory. The Galerkin method and harmonic balance method are adopted to obtain the amplitude-frequency response characteristic and phase-frequency response characteristic of the micro-beam structure. Then the effects of the nonlinear air damping force and the geometric nonlinearity on the resonance frequency and stiffness of micro-beam structure are analyzed.
The Application of P-R Criterion in Chaos Identification of Micro Piezoelectric Laminated Beam
Authors: Wu Shunhai , Hu Haitao , Chen Changping , Dai Liming
Published: August 2012

In this paper, based on Euler-Bernoulli assumptions and piezoelectric theory, taken electric excitation loads generated by AC and DC’s interactions, control voltage of piezoelectric layer and geometric nonlinearity into consideration, the nonlinear differential governing equation of piezoelectric laminated microbeam is established. The equation is solved by Galerkin method and mathematical tools. Making use of P-R criterion method, the analysis of single parameter bifurcation is carried on firstly to understand the characteristics of system, and the effects of multiple parameters variation on nonlinear dynamic characteristics of system are discussed in detail. The results can be used for the design of such micro-structures.
Finite Element Modeling and Analysis of Structural Joints Using Nuts and Bolts
Authors: Bhonge Prasannakumar S. , Foster Brian D. , Lankarani Hamid M.
Published: August 2012

The majority of the structural failures of mechanical structures and systems are found in joints rather than continuous material. Joints have historically consisted of assemblies involving nuts, bolts, screws, etc. and the design and analysis of these joints can be quite challenging. This work provides two baselines on the finite element modeling (FEM) methods and analysis of a nut and bolt joint. The first baseline involves a basic modeling method using linear calculation of 2D plates and bar elements, and the second baseline involves one of the more complex methods using non-linear calculation of 3D solids. The two methods are described for modeling of a joint for two test conditions, namely the double shear joint in tension with two different bolt sizes and two plate thicknesses. First, the simplified method of rigid elements and equivalent strength beam elements is considered. This technique lacks the simulation of bearing stresses, stress concentration at the bolt hole location, and bending stiffness of the bolt. The second method, uses 3D models that provides the actual nut and bolt surfaces, bearing stresses are introduced in the joint modeling. Classical hand calculations are carried out on the static tests and compared with the FEM results. Additionally, the effects of element mesh refinement on the nut and bolt contact surfaces, and types of contacts are analyzed for the 3D models. A parametric study is carried out on the stresses developed and stress concentration factors.
Development of a Curved Hopkinson Bar for Long Wavelength Impact Events
Authors: Vallee Glenn E. , Bowen Micah C.
Published: August 2012

A study of the feasibility of using a curved Hopkinson bar for the measurement of impact load and energy transmission is presented. The length requirements of straight prismatic bars commonly used to measure long wavelength impact events are often prohibitive, and the use of curved bars can result in a significant increase in wavelength capabilities while reducing the overall size of the measurement apparatus. The ABAQUS/Explicit finite element analysis (FEA) program is used to model steel bars of circular cross section bent with various bend radii and at various bend angles ranging from 15 to 180 degrees. A uniform compressive pressure pulse of known amplitude and wavelength is applied to the FEA models and the wave propagation behavior predicted by ABAQUS/Explicit is then compared to the response predicted by the theory of wave propagation in curved bars and experiments performed using curved bars. The numerical results show good agreement with the theoretical and experimental results. Significant distortion of the incident wave as it travels around the bend results in a transmitted pulse that is not characteristic of the input pulse, particularly at larger bend angles and long wavelengths. The energy transmitted around the bend radius contains only a fraction of the initial impact energy due to large reflections that develop at the bend radius, and this loss increases significantly at larger bend angles and smaller bend radii. However, the transmitted energy can be used to predict the incident energy at a variety of bend angles and bend radii. A curved carbon steel Hopkinson bar is fabricated with a bend angle of 180 degrees and instrumented with strain gauges to monitor the wave propagation within the bar at several locations resulting from a compressive impact pulse. The experimental results agree well with the results predicted using explicit dynamic FEA. The results of this study indicate that a curved Hopkinson bar can be used to predict the impact energy applied to the incident end of the bar using the measurement of the energy transmitted around the bend in the bar. The overall length of the curved Hopkinson bar apparatus can be significantly less than a comparable straight bar apparatus.
Adjustable Electromechanical Wedge Brakes With Reduced Energy Consumption
Authors: Ivanov Vasily A. , Ayalew Beshah
Published: August 2012

An Electromechanical Wedge Brake (EWB) has an inherent self-reinforcing capability that translates into reduced actuation forces and subsequently into reduced energy requirements. However, to avoid jamming the brake, there is a need for a dedicated means of adjusting the effective wedge angle in order to modulate the braking forces and to accommodate changing pad friction conditions. Earlier prototypes had one actively controlled moveable wedge with a fixed wedge angle. In this paper, two new designs are considered and compared with the conventional EWB design. The first one uses pre-defined wedge shapes in a self-adjusting design with one movable wedge. The second uses an externally adjustable wedge and an actively movable wedge with similarly pre-defined wedge shapes. These designs can be employed to further reduce the required actuator forces beyond what is possible with the conventional design. The benefits of these self-adjusting and externally adjustable EWB designs are demonstrated using dynamic model simulations for a typical hard braking event.
Slouching Toward Disaster
Authors: Batzer Stephen A. , Morse John S.
Published: August 2012

“But, who cares, it’s done, end of story, [we] will probably be fine and we’ll get a good cement job.” This is an oft-repeated email quotation from one BP engineer to another on April 16, 2010, just four days before the Macondo well blew out in the Gulf of Mexico. Although these two men survived, 11 others did not. The well blowout also brought with it poisoning of the ecology and vast financial loss. This quote, part of a discussion about centralizers for the well (BP ended up with just six instead of the planned 16 or 21), seems to epitomize the attitude regarding a series of decisions made about the well’s design. The product of the decisions was complete loss and worse. However, the parties did not seem to be aware of the importance of their individual decisions or their consequences as they were making them. This disaster, like many others, seemed in retrospect to unfold in slow motion, and the players involved did not perceive the sheer cliff before them until they had transgressed its edge. This paper will examine decision-making processes in the Deepwater Horizon blowout and a series of other disasters, both high and low profile events. All of these preventable events stemmed from decision-making failures. These failures include disregarding existing information, failing to soberly extrapolate “what if?” when existing information contained uncertainty, failing to obtain vital missing information, failing to question decisions — particularly from those considered authoritative, and a cavalier attitude regarding rules because probably nothing will happen anyway. “Who cares?”
Destruction of Water-in-Oil Emulsions in Electromagnetic Fields
Authors: Kovaleva Liana , Musin Ayrat , Zinnatullin Rasul , Akhatov Iskander S.
Published: August 2012

The problem of water-in-oil emulsion destruction is related to many technological processes in the oil-and-gas industry, especially in extracting and processing of oil, preparation and transportation of oil, and liquidation/recycling of oil-sludge barns. High stability of water-in-oil emulsions is principally conditioned by the presence in oils of heavy high-molecular polar components that envelope water droplets and prevent coalescence of these droplets. Using conventional techniques to destroy the emulsions yields no positive results. Employing electromagnetic field energy is one of the ways to address this problem. The paper presents the results of an experimental study of the water-in-oil emulsion destruction in radio-frequency and microwave electromagnetic fields. A mathematical model is also proposed to describe the process of electromagnetic impact on water-in-oil emulsions.
Ring-Shaped Sessile Droplet
Authors: Chugunov Svyatoslav S. , Schulz Douglas L. , Akhatov Iskander S.
Published: August 2012

It is recognized that small liquid droplet placed on the solid substrate forms equilibrium contact angle that can be obtained from well-known Young’s law. Previously, deviations from Young’s law were demonstrated for the droplets exposed to external fields (gravity, electric, etc) and for the droplets on non-homogeneous substrates. This work reveals that the Young’s equilibrium contact angle can be altered by geometrical reasons only. We consider a ring-shaped droplet on a solid substrate as a test structure for our discussion. We use the global energy consideration for analysis of system equilibrium for the case of freely deposited liquid with no external forces applied. The theoretical analysis shows that steady ring-shaped liquid structure on a solid substrate does exist with contact angles on both contact lines to be different from the Young’s equilibrium contact angle.
Analytical Dynamics of Complex Motions in a Train Suspension System
Authors: Luo Albert C. J. , O’Conner Dennis
Published: August 2012

Nonlinear dynamical behaviors of a train suspension system with impacts are investigated. The suspension system is described through an impact model with possible stick between a bolster and two wedges. The analytical conditions that reflect the motion mechanisms for the complex motion are given. The mapping structures for periodic and chaotic motions of such a system can be described. The analytical prediction of the complex motions can be conducted from the mapping structure, and numerical simulations for periodic and chaotic motions can be carried out in sequel.
Bifurcation Analysis of a Fermi-Acceleration Oscillator Under Different Excitations
Authors: Luo Albert C. J. , Guo Yu
Published: August 2012

In this paper, switchability and bifurcation of motions in a double excited Fermi acceleration oscillator is discussed using the theory of discontinuous dynamical systems. The two oscillators are chosen to have different excitation and parameters. The analytical conditions for motion switching in such a Fermi-oscillator are presented. Bifurcation scenario for periodic and chaotic motions is presented, and the analytical predictions of periodic motions are presented. Finally, different motions in such an oscillator are illustrated.
Stability and Bifurcation Analysis of Periodic Motions in a Periodically Forced Duffing Oscillator
Authors: Luo Albert C. J. , Huang Jianzhe
Published: August 2012

In this paper, the analytical, approximate solutions of period-1 motions in the nonlinear damping, periodically forced, Duffing oscillator is obtained. The corresponding stability and bifurcation analysis of the HB2 approximate solution of period-1 motions in the forced Duffing oscillator is carried out. Numerical illustrations of period-1 motions are presented.
Design and Fabrication of a Hybrid Body-Powered Prosthetic Hand With Voluntary Opening and Voluntary Closing Capabilities
Authors: Sullivan Timothy , Teh Kwok Siong
Published: August 2012

There are currently over 500,000 people with upper extremity amputations living in the United States. Among this population—despite the introduction of advanced myoelectric technology—body-powered hand prosthetics remain the hand prosthetic of choice because they are inexpensive, durable, and are easier and cheaper to maintain than myoelectric prosthetics. Yet, body-powered prosthetics tend to have less functionality than myoelectric prosthetics because their output is often limited to a single function—voluntary opening (VO) or voluntary closing (VC). Although these functions serve the same purpose—to grasp an object—they are executed in opposite ways, catering to different body movements, hand actions, and rest positions. In reality, a human hand is more adequately modeled by a VO/VC hybrid mechanism than a standalone VO or VC mechanism. There is therefore a critical need to develop prosthetics with combined VO and VC functions in order to augment their capabilities and to more closely mimic the human hand. This paper presents the design, fabrication, and analysis of a combined, hybrid VO and VC prosthetic hand that is simplistic and electronics-free. To realize a hybrid VO and VC prosthetic hand, we designed and fabricated an easy push-pull switching mechanism for changing between VO and VC and investigated the efficacy of this switching mechanism in response to the wide range of force transmission necessitated by the VC and VO functions. The mechanical switching mechanism is activated with a force of 1 to 1.5N. The mechanism itself is constructed using a system of gears that allow for the direction of force to be changed, effectively providing the foundation for which VO and VC functions can exist in a single prosthetic. This switching mechanism could potentially be used in combination with a number of different prehensor types, catering to a wide range of users. We used a 3.5″ TRS-style prehensor for our prototype and designed the switch to apply a 21 N force while in VO mode and up to 100 N while in VC mode. In our design, VO and VC modes offer characteristics that are identical to existing VO and VC designs, with a few exceptions. These exceptions include an increase in weight, as low as 12% energy loss in VC mode and 9% loss in VO mode due to gears, more complex mechanics, larger required space, and a higher spring force in VC mode. Future design improvements will be discussed in this paper.
Mechanism of Thermal Conductivity Reduction From Suspended to Supported Graphene: A Quantitative Spectral Analysis of Phonon Scattering
Authors: Qiu Bo , Ruan Xiulin
Published: August 2012

In this work, we perform molecular dynamics (MD) simulations together with phonon spectral analysis to predict the thermal conductivity of both suspended and supported graphene. We quantitatively address the relative importance of different types of phonon in thermal transport and explain why thermal conductivity is significantly reduced in supported graphene compared to that in suspended graphene. Within the framework of equilibrium MD, we perform spectral energy density analysis to obtain the phonon mean free path of each individual phonon mode. The contribution of each mode to thermal conductivity is then calculated and summed to obtain the lattice thermal conductivity in the temperature range 300–650 K. Our predicted values and temperature dependence for both suspended and supported graphene agree with experimental data well. In contrast to prior studies, our results suggest that the contribution from out-of-plane acoustic (ZA) branch to thermal conductivity is around 25–30% in suspended graphene at room temperature. The thermal conductivity of supported graphene is predicted to be largely reduced, which is consistent with experimental observations. Such reduction is shown to be due to stronger scattering of all phonon modes rather than only the ZA mode in the presence of the substrate.
Evaluating the Technical, Economic, and Environmental Impact of the Level of Decentralization in Energy Investment Decisions
Authors: Liu Yiwen , Hawthorne Bryant D. , Panchal Jitesh H.
Published: August 2012

The goal of this paper is to analyze the impacts of the level of decentralization in energy investment decisions on the technical, economic, and environmental performance. The analysis is important because of the increasing popularity of decentralized renewable energy technologies such as solar cells, fuel cells, wind power, etc. In this paper, we show that depending on the level of decentralization at which the decisions are made, the overall system performance is different. We consider an investment decision that can be made at varying levels of decentralization. The HOMER software is used for analyzing scenarios at different levels. The goal of this paper is not to present a new approach for design but to illustrate the problem itself. Using this problem, we highlight the need to establish new methodologies and tools to make such decisions related to the energy infrastructure.
Pneumatic Hand Rehabilitation Device
Authors: Gagliard Robert P. , Fregeolle Robert , Sharaf Khalid M. , Zenouzi Mansour , Dow Douglas E.
Published: August 2012

A prototype of a pneumatic device for rehabilitation of the hand was designed, built and tested. Progressive impairment of hand function may result from a prolonged condition of hemiparesis, such as resulting from stroke. Reduced daily use of the affected limb, spasticity and contracture contribute to progressive impairment. Physical therapy attenuates the impairment in many patients, but regular sessions of physical therapy are difficult to maintain due to the associated costs, limited insurance coverage, and necessity of being at the clinic for each session. Systems or devices suitable for home-based therapy sessions would widen the accessibility of physical therapy to more patients. However, reported therapeutic systems appear to be expensive, heavy and complicated, thus limiting their suitability for widespread application in home settings. Recent reports of pneumatic based hand therapy systems suggest a platform for hand rehabilitation that would be simpler, lighter, less expensive, and have a lower risk of safety concerns. The design utilized in this project has the affected hand encased in a glove apparatus that has an embedded air bladder positioned ventral to each of the five digits on the palmer side of the hand, such that the bladder acts to assist extension of each finger and thumb as internal air pressure increases. Several alternative designs of glove-bladder combinations were designed, fabricated and tested. An electro-pneumatic regulator (SMC Corp. of America, Noblesville, IN) controlled the pressure of air to the bladders from an air compressor. The pneumatic regulator was controlled by a custom designed and assembled microcontroller (Arduino, open source) based control system. The microcontroller controlled solenoids that functioned as valves for the passage of air to the bladders from the pneumatic regulator, one solenoid for each of the 5 bladders in a glove. Tests were done to compare alternative glove-bladder designs. For a bladder corresponding to one digit, the relations between air pressure and the resulting torque were explored using a system of weights. Moreover, for constant pressure levels, the relations between angle of a digit and torque were explored. The pneumatic hand rehabilitation system developed in this project shows promise toward development of pneumatic hand therapy systems that would be suitable for home-based therapy.
Investigation of Interaction of Laser Generated Lamb Waves With Structures of Interest
Authors: Yang Lei , Ume I. Charles
Published: August 2012

Laser generation/EMAT (electromagnetic acoustic transducer) reception ultrasonic inspection technique shows a great promise in the field of Non-Destructive Testing of welds due to its non-contact nature. However, the broadband nature of laser generation and the dispersive characteristic of Lamb waves make the laser generated ultrasonic signals in thin structures extremely complicated. In order to ease the interpretation of received signals, it is desirable to investigate the interactions of different structural features with Lamb waves and find their related signatures in signal, which offers the potential to detect different types of weld defects using a single test procedure. This work proposed a technique based on 2-D Fourier Transformation to investigate the laser generated Lamb waves experimentally and to find the most sensitive predictors in EMAT received signals corresponding to a specific structural feature of interest. The amplitudes of different Lamb wave modes in the wave-number/frequency domain provide a wealth of information. The demonstration of the technique was carried out on aluminum plates with isolated rectangular notches of different depths. The procedure introduced here is general which can be employed in other applications of Non-Destructive Testing.
The Research of Energy Conversion and Heat Transfer in the Ceramic Foams of Solar Energy Converter
Authors: Deng Yangbo , Su Fengmin , Yan Chunji
Published: August 2012

The solar energy converter in Concentrated Solar Power (CSP) system, applies the solid frame structure of the ceramic foams to receive the concentrated solar radiation, convert it into thermal energy, and heat the air flow through the ceramic foams by convection heat transfer. In this paper, first, the pressure drops in the studied ceramic foams were measured under all kinds of flow condition. Based on the experimental results, an empirical numerical model was built for the air flow through ceramic foams. Second, a 3-D numerical model was built, for the receiving and conversion of the solar energy in the ceramic foams of the solar energy converter. Third, applying two aforementioned numerical models, the numerical studies of the thermal performance were carried out, for the solar energy converter filled with the ceramic foams, and results show that the structure parameters of the ceramic foams, the effective reflective area and the solar radiation intensity of the solar concentrator, have direct impacts on the absorptivity and conversion efficiency of the solar energy in the solar energy converter. And the results of the numerical studies are found to be in reasonable agreement with the experimental measurements. This paper will provide a reference for the design and manufacture of the solar energy converter with the ceramic foams.
The Influence of Burner Nozzle Angle for Flow Field and Heat Transfer of Ultra-Supercritical Tower Boiler
Authors: Chen Saike , Yang Mo , Zhang Yuwen , Kang Zhangyang
Published: August 2012

The angle of burner nozzle is an important factor for burning of ultra-supercritical tower boiler. In this paper, gassolid multiphase flow and combustion in 1000MW Ultra-supercritical tower furnace were of the numerical simulation under different conditions. The angle of burner nozzle deflects downward, and the angle is 0°, 3°, 6°, 9° and 12°. Flow model is turbulence and SIMPLE algorithm and QUICK scheme are employed. Through theoretical analysis of different conditions (the velocity distribution in different face; the velocity vector in furnace; the temperature in furnace; the NOx, CO2 and O2 emissions in outlet), finally, the law of the angle of burner nozzle for flow field and heat transfer in ultra-supercritical tower boiler is found.
Optimal Control of Clamped-Free Conical Shell Using Diagonal Piezoelectric Sensor and Actuator
Authors: Li H. , Chen Z. B. , HU S. D. , Tzou H. S.
Published: August 2012

In this paper, optimal vibration control of a clamped-free conical shell is presented. A diagonal piezoelectric sensor/actuator (S/A) pair is proposed to control the axial, bending and transverse vibrations of the conical shell. The modal functions are adapted to satisfy the clamped-free boundary condition. Based on the independent modal control method, the response of conical shell to external excitations can be represented by the summation of all participating natural modes and their respective modal participation factors and each mode can be controlled independently. The modal equation is transformed into the linear state space form. The modal participation factor and its time derivative are chosen to be the state variables. The sensing signals are chosen to be the output vector. The modal force is chosen to be the control input vector. The linear quadratic (LQ) controllers are designed for each independent mode. The optimal gain matrix is related to the ratio between control voltage and sensing signal by the modal control force per unit voltage and the sensing signal. Numerical examples show that, the proposed optimal control method can achieve significant active control effects and the optimal gains are mainly related to the modal velocity. This effect varies with the locations of S/A pair and the mode of the shell. The results indicate that, to achieve the best control effects for all wanted modes, the optimal controller and the optimization of the S/A location should be taken into account in the design of the optimal controller.
Three Dimensional Numerical Simulation of the Natural Convection in an Annulus With an Internal Slotted Cylinder
Authors: Yang Mo , Wang Jin , Zhang Kun , Li Ling , Zhang Yuwen
Published: August 2012

Detailed numerical analysis is presented for three-dimensional natural convection heat transfer in annulus with an internal concentric slotted cylinder. The internal slotted cylinder and the outer annulus are maintained at uniform but different temperatures. Governing equations are discretized using control volume technique based on staggered grid formulation and solved using SIMPLE algorithm with QUICK scheme. Flow and heat transfer characteristics are investigated for a Rayleigh number range of 10 to 106 while Prandtl number (Pr) is taken to be 0.7. The results indicate, at Rayleigh numbers below 105, the system shows two dimensional flow and heat transfer characteristics. On the other hand, the flow and heat transfer shows three dimensional characteristics while for Rayleigh numbers greater than 5×105. Comparison with experimental results indicated that the numerical solutions by three dimensional model can obtain more accuracy than the numerical solutions by two dimensional model. Besides, Numerical results show that the average equivalent conductivity coefficient of natural convection heat transfer of this problem can be enhanced by as much as 30% while relative slot width is more than 0.1.
Modal Energy Transduction of a Cylindrical Shell Laminated With a Segmented Piezoelectric Layer
Authors: Li X. , Chuang K. C. , Li H. , Tzou H. S.
Published: August 2012

Energy transduction between the mechanical and electric effects has been evaluated over the years. Energy harvesting based on the direct piezoelectric effect using the curvature structures is a new endeavor in engineering applications. This study focuses on energy harvesting from mechanical vibrations through a simply supported circular cylindrical shell laminated with segmented piezoelectric energy harvester patches. The voltages (or modal signals) induced by the modal strains of the piezoelectric patch due to the direct piezoelectric effect can be further converted to modal energies. Spatial distributions of the modal energies are evaluated and compared in three piezoelectric energy harvester patch sizes, and key design parameters. The objective of this study is to investigate the spatial distribution characteristic of the modal energy and evaluate the effects of energy harvester patch size and physical parameters on the generation of the modal energy. These data evaluated in this study can be used as guidelines to design the optimum piezoelectric energy harvester in practical engineering applications.
Noise Prediction in Design of Low Pressure Rotor-Only Axial Fans
Authors: Zhang Jie , Zhou Shaoping , Ge Xiaoling
Published: August 2012

A noise prediction program has been incorporated into a blade design process of the arbitrary vortex flow rotor-only axial fans which are widely used in low pressure applications. Parametrical studies of different geometrical designs are conducted to investigate the influence on noise radiation from axial fans. The noise prediction program is based on the Carolus’s semi-empirical model, in which the broad-band aeroacoustic noise is mostly attributed to three independent sources: incident turbulence, turbulent boundary layer, and blunt trailing edge. In addition, the well-known Fukano’s vortex shedding model is also utilized for indicative comparison. It is indicated that the total sound pressure level is most sensitive to the flow relative velocity, while the chord length can be considered as a secondary cause.
Dynamical Analysis of Magnetorheological Rotational Flow
Authors: Ashrafi Nariman , Mortezapoor Abdolreza
Published: August 2012

Stability of the magnetorheological rotational flow in presence of magnetic excitation in the axial direction is examined. The Galerkin projection method is used to derive a low-order dynamical system from the conservation of mass and momentum equations while mixed boundary conditions are assumed. In absence of magnetic excitation, the base flow loses its radial flow stability to the vortex structure at a critical Taylor number. The emergence of the vortices corresponds to the onset of a supercritical bifurcation. The Taylor vortices, in turn, lose their stability as the Taylor number reaches a second critical number corresponding to the onset of a Hopf bifurcation. The axial magnetic field turns out to be a controlling parameter as it alters the critical points throughout the bifurcation diagram.
Self Activation of the Gyroscopic Power Generator
Authors: Kamiya Yohei , Hosaka Hiroshi
Published: August 2012

In order to solve energy supply problems in ubiquitous information systems, a new driving technique for the gyroscopic power generator has been developed. The generator was made to work as a motor, Which was started automatically by providing an initial velocity. The ability to generate 0.7 W of power from vibration, the frequency of which is as low as 1 Hz, as well as the ability to charge 5-cells of NiMH batteries were demonstrated.
Stress Analysis of Pseudo-Plastic Flow Between Rotating Cylinders
Authors: Ashrafi Nariman , Haghighi Habib Karimi
Published: August 2012

Stress analysis of Pseudo-Plastic flow between rotating cylinders is studied in the narrow gap limit. The Galerkin projection method is used to derive dynamical system from the conservation of mass and momentum equations. Flow parameters were obtained using IMSL and also verified by Mathematica Software. Stresses are computed in a wide range of the Pseudo-Plastic effects. Azimuthal stress was found to be far greater than other stress components. All stress components increased as Pseudo-Plasticity decreased. Furthermore, complete stress and viscosity maps are presented for different scenarios in the flow regime.
Engineering Out the Hazards of a Machine Shop
Authors: Wirth Sean , Montes Ruben , Bell Susan , Saltzman Michael
Published: August 2012

A machine shop environment presents a high potential for occupational injuries and fatalities. A combination of rotating spindle, coolant spatter, cutting tool activity, and sharp airborne chips, occurring during the metal cutting process, creates a significant hazard for equipment operators. The danger of working in this environment is reflective in industry TRIRs (Total Recordable Incident Rate) which fall between 2.7 (Oil and Gas Manufacturing) and 5.5 (Metal Manufacturing) based on the latest USA Industry and Illness Data. This case study highlights how the Navigation Manufacturing facility (500 employees, 100 CNC machines) — identified numerous safety issues in its machine shop environment and processes, and undertook a three-step program for “engineering out” those hazards. 1. The first step involved modifying machinery guarding and improving the internal visibility of parts during machine operation. 2. The second step took traditional secondary process tasks performed manually outside the machine — de-burring, marking, cleaning — and incorporated these tasks into the machining effort to reduce potential operator hand injuries that could occur during interaction with the part. 3. Thirdly, the handling of production parts was improved with the use of parts catchers, modified forklifts, and new safer material lifting devices, further reducing the likelihood of other bodily injury. Implementation of “hands-free” machine and equipment improvements and enhanced process practices has allowed the facility to achieve over two million hours without a Recordable Injury (TRIR), over 9 million hours without a Days Away from Work Case (DAFWC), and a TRIR of less than 0.4 for the last 5 years.
Sample Biomedical Projects Carried Out by Undergraduate Mechanical Engineering Students
Authors: Lifer Kathleen C. , VanAtta Jason S. , Bauman Judson M. , Marquart Jed E. , Shen Hui
Published: August 2012

As reported by the ASME Center for Education Task Force [1], human health will be one of the major areas in which mechanical engineers will take the leadership position to develop innovative technologies in the future. To adapt to the transforming role of the mechanical engineering profession, undergraduate education of mechanical engineering needs to guide students to apply engineering principles in this area. In this paper, the development of an undergraduate biomedical course in a mechanical engineering major is introduced. Several course projects developed by mechanical engineering undergraduate students are described. These projects focused on the study of biomedical problems using engineering problem solving skills. The projects were started with the analysis of injuries or diseases of patients. Then, injuries and/or possible treatments were analyzed from the viewpoint of a mechanical engineer. All of these students’ projects are summarized in this paper and a few projects discussed in detail. Among these projects, the flow and pressure distributions of different types of heart valves were calculated using computational fluid dynamics; the consequence of injuries of joint cartilage was analyzed with bearing design theory; the treatment of a muscle hernia was calculated using the finite element method. These projects encouraged students to appreciate engineering applications in fields other than traditional fields such as automobile and aircraft design. The results of the projects are also useful in practice. The course model is applicable for engineering programs in other small teaching universities.