bluuebunny/crossref_metadata_2025 huggingface dataset:
Strategic Alignment, Planning and Operations in the Supply Chain: A Case Study
Authors: Gurjar Nikhil S. , Jog S. D.
Published: May 2008

The present work is a case study conducted on the Indian operations of a leading white goods manufacturer in the world, with a focus on the alignment and planning of the primary movements in the distribution resource planning cycle/manufacturing cycle. The present system at the company is analyzed for the three components viz. supply chain design, supply chain planning and supply chain operations. The characterization of the present system is based on high-implied demand uncertainties, high forecast errors, provisions for mixed order matching, seasonality of demands, end of month peak characterization and the irregular flow of information. The initial analysis is based on a simple queuing model that incorporates the theory of constraints to evaluate the criticality of the information flow in the system. This model is then extended to incorporate other parameters required in the strategic alignment of the system with the corporate objectives. The current initiatives in the company are then developed further into a strategic plan that incorporates considerations of new product launches, decreasing product life cycles, fragmentation of supply chain ownership, globalization and other difficulties in execution.
The Impact of Sheet Metal Stamping on Manufacturing and Economic Growth of the United States in the Early 20th Century
Authors: Vohnout Vincent J.
Published: May 2008

A vast array of manufactured articles containing metal components utilize power press methods in their production. The common aspect of these methods is the use of specialized dies and the mechanical energy of the press machine to impart the required finished shape with a minimum of time and material loss. The innovation of power press metal forming methods in conjunction with advances in sheet rolling technology can be credited with a significant portion of the United States economic growth from manufacturing between 1890 and 1940. Of the many variations of power press metal forming processes that now exist, sheet stamping is found to be the most significant to the economic development of the U.S. as a synergetic partner of the new automobile industry. Data from the 1929 Census of Manufactures is used to generate a Social Savings metric which estimates the effect of the use of sheet stamping in terms productivity gained. The estimated Social Savings of this very small sector of manufacturing represents a tenth of one percent of the total Value Added by all U.S. industries in 1929.
Paradigm Shifts in Manufacturing: Observing From the Sides of Technological Evolution and Demand of the Society
Authors: Honda Hiroshi
Published: May 2008

The subject paper discusses some of the paradigm shifts observed in manufacturing in heavy and other industries, with a focus on shipbuilding, such as the shifts toward gigantic structures with the advent of riveting and welding technologies, toward labor and total cost saving, speedy systems with the availability of automation technology, various computers and workstations, and advanced information technology (IT). This has lead to a paradigm shift from hardware- to software-oriented systems. The advancement of material and its manufacturing technology has lead to availability of light-weight vessels and higher performance goods, and oil crises have lead to a paradigm shift toward energy conserving vessels and goods. The advent of semi-conductor and integrated circuits has lead to a paradigm shift from “Big is great” to “Small is beautiful” worlds, leading to further emphasis and promotion of micro- and nano-technologies. An overview and summary of those paradigm shifts and future trends are also given in this paper.
Application of Cogeneration to the Heating of Natural Gas in Pipeline
Authors: Fushimi Alberto , Sosa Mari´a Isabel , Pitrelli Guillermo , Vasquez Vanesa I. , Vido Luis , Za´rate Leandro
Published: May 2008

In the Southern Region of our Country (Argentina), pipeline natural gas is heated up to suitable temperatures by combustion of natural gas in indirect type heating systems. In one of the points in which such heating is necessary, the pipeline that transports about 14 million standard cubic meters per day of natural gas at 45 bar of pressure and whose temperature is wanted to rise from −2°C to 30°C, is placed about 500 m away from of a regional thermoelectric power station. It has 3 7 MW gas turbines, exhausting 25.8 kg/s of combustion gases at 510°C each. A preliminary calculation showed that the waste heat of one of them can closely supply the necessary duty for gas heating. In this work, a preliminary analysis and economics of the system are described.
A Decomposition Strategy Based on Thermoeconomic Isolation Applied to the Optimal Synthesis/Design and Operation of a Fuel Cell Based Total Energy System
Authors: Georgopoulos Nikolaos G. , von Spakovsky Michael R. , Mun˜oz J. Ricardo
Published: May 2008

A decomposition methodology based on the concept of “thermoeconomic isolation” applied to the synthesis/design and operational optimization of a stationary cogeneration proton exchange membrane fuel cell (PEMFC) based total energy system (TES) for residential/commercial applications is the focus of this paper. A number of different configurations for the FC based TES were considered. The most promising set based on an energy integration analysis of candidate configurations was developed and detailed thermodynamic, kinetic, geometric, and economic models at both design and off-design were formulated and implemented. An original decomposition strategy called Iterative Local-Global Optimization (ILGO) developed in earlier work by two of the authors was then applied to the synthesis/design and operational optimization of the FC based TES. This decomposition strategy is the first to successfully closely approach the theoretical condition of “thermoeconomic isolation” when applied to highly complex, nonlinear systems. This contrasts with past attempts to approach this condition, all of which were applied to very simple systems under very special and restricted conditions such as those requiring linearity in the models and strictly local decision variables. This is a major advance in decomposition and has now been successfully applied to a number of highly complex, highly non-linear, and dynamic transportation and stationary systems. This paper presents the detailed results from one such application.
A Two-Temperature Model for the Analysis of Passive Thermal Control Systems for Electronics
Authors: Krishnan Shankar , Murthy Jayathi Y. , Garimella Suresh V.
Published: May 2008

Passive control of unsteady thermal loads using phase change materials is being explored for a variety of military and consumer electronics applications. The phase change materials usually have very low thermal conductivity. To enhance the thermal response of the system, thermal conductivity enhancers like metal foams, internal fins and metal filler particles have been proposed. Local thermal equilibrium between the solid matrix and the fluid is not ensured in such systems since the thermal conductivities and heat capacities for the fluid and solid are very different. The use of a single volume-averaged energy equation for both the phases cannot be justified in such situations. A two-medium approach is developed in the present work to account for the local thermal non-equilibrium. Separate energy equations are written for the solid and fluid respectively, and are closed using a steady-state interstitial heat transfer coefficient between the two phases. A general momentum equation which includes the Brinkman-Forchheimer extension to Darcy flow is employed. The resulting equations are solved using a finite volume scheme. The influence of various parameters such as the ratios of fluid to solid conductivities and heat capacities, porosity, Rayleigh number, Prandtl number, and Darcy number on the thermal and flow fields is investigated. The importance of using a two-medium approach for such situations is illustrated using the results obtained.
A Model-Based Feed-Forward Controller Scheme for Accurate Chilled Water Temperature Control of Inlet Guide Vane Centrifugal Chillers
Authors: Jia Yongzhong , Reddy T. Agami
Published: May 2008

Capacity control in most commercial centrifugal chillers is achieved by inlet guide vanes, which are activated by the leaving chilled water temperature sensor. Due to mechanical reasons, vane control is done discretely, and not continuously. The control module compares the value provided by the temperature sensor to pre-set control band values, and if those bands are exceeded, it sends a signal to the vane control motor to adjust the vane position by one step that could be upwards or downwards. The advantage of this type of discrete control method is its simplicity. Normally, the accuracy in the outlet chilled water temperature is of the order of 0.5°C, which is acceptable for normal cooling plants such as used in office buildings. However, there are applications such as in pharmaceutical processes, mechanics labs, or instances in chemical processes where more accurate control is required (sometimes as low as 0.05°C). This paper proposes a simple method to achieve such tight control without any hardware modifications. The basis of this method is a transient physical inverse model of the refrigerant boiling process in the evaporator, in conjunction with a feed-forward control scheme. The model parameters need to be identified from monitored data since they are chiller-specific. This paper describes the model, and applies it to one-minute monitored data from an actual chiller plant of 1580 kW (450 Tons). It is demonstrated that for this specific chiller such a control scheme has the potential to improve control accuracy by about 28% as compared to the traditional control method.
Repetitive Control for Linear Time Varying Systems
Authors: Sun Zongxuan , Tsao Tsu-Chin
Published: May 2008

Repetitive control that asymptotically tracks or rejects periodic signals has been widely used in many applications. For linear time invariant system, this problem has been thoroughly studied and solved. This paper presents the analysis and synthesis of repetitive control algorithms to track or reject periodic signals for linear time varying systems. Both continuous and discrete time domain results will be presented. A time varying internal model is embedded in the feedback loop to ensure asymptotic performance. It is shown that asymptotic performance can’t be achieved with a finite dimensional controller in the continuous time domain, while it is possible in the discrete time domain. Simulation results demonstrate the effectiveness of the proposed algorithms.
Position-Dependent Disturbance Rejection Using Spatial-Sampling Robust Repetitive Control With Actuator Saturation and Load Uncertainty
Authors: Chen Cheng-Lun , Chiu George T.-C.
Published: May 2008

This paper proposed modification to the previous design of a two degree-of-freedom (TDOF) repetitive control system for a motor/gear transmission system subject to time-varying position-dependent disturbances. The new discrete-position repetitive controller was operated in spatial domain where those periodic disturbances are stationary, i.e. their spatial frequencies do not vary with the nominal operating velocity of the transmission system. Thus, performance of the repetitive controller will not be compromised as the nominal velocity of the system may change due to friction or load variation. Besides, the modified control system also inherited other nice properties, e.g. robustness to actuator saturation and model uncertainties, from the previous design. Simulation and experimental results for a typical 600-dpi laser printer further justified the design by showing significant transmission error reduction. Halftone banding due to periodic transmission errors was also eliminated on printed images for the compensated system.
Strength and Finite Element Analysis of Single-Lap Joints With Adhesively Filled Columns
Authors: Liu Jiemin , He Songjian , Sawa Toshiyuki
Published: May 2008

This paper introduces a novel approach to increasing the loading ability of adhesive joints by adding adhesively filled columns. Following procedures are taken for making adhesive joints with adhesively filled columns: At first, holes are drilled at the overlap region of adherends, and then these holes are filled with adhesive or reinforced columns (such as reinforced fiber composite, metal columns, etc.). At the same time, adhesive is also applied on the surfaces of the overlap of adherends. After cured, the reinforced columns and adhesive in the holes form so-called adhesively filled columns. In this study, strengths of single-lap adhesive joints with adhesively filled columns were measured experimentally. Stress and strain distributions at typical positions in adhesive layer were analyzed by using Finite Element Method (FEM). Failure mechanics of the joint were analyzed. It was found that to well-bonded joints, the metal columns make the joint strength increase obviously and the joint strength increases with increasing of adherend thickness. Therefore, using reinforced columns in adhesive joints is an effective approach to generalizing adhesive joints from thin-walled joints to loading sizable bulk ones.
An Experimental Study for an Iterative Learning Control Scheme With Adaptive Filtering
Authors: Zheng Danian , Alleyne Andrew
Published: May 2008

This paper presents experimental investigations into a novel approach which circumvents a classic tradeoff between robustness and performance in Iterative Learning Control. The tradeoff is usually performed by designing an appropriate filtering mechanism to compensate for non-perfect resetting and noise. Time-Frequency analysis is used to examine the frequency content of error signals over the compact time support of the reference signal. This then allows the filter to effectively change its bandwidth as a function of time thereby allowing high frequency system dynamics to enter into the learning process at the appropriate time instants. At the same time, robustness is maintained by reducing the bandwidth of the filter when the system dynamics do not exhibit high frequency characteristics so as to attenuate the effect of noise on the learning stability. This adaptive Q-filter Iterative Learning Controller is needed for systems that have non-smooth nonlinearities and the advantages are demonstrated here in the simulations and experiments. A specially designed experimental study shows the fundamental limits that can affect its effectiveness.
On the Adaptive Control of Mechanical Systems With Time-Varying Parameters and Disturbances
Authors: Pagilla Prabhakar R. , Zhu Yongliang
Published: May 2008

In this paper, we propose and investigate a new adaptive control algorithm for mechanical systems with time-varying parameters and/or time-varying disturbances. The proposed method does not assume any structure to the time-varying parameter or disturbance. The idea is based on the expansion of the time-varying parameter/disturbance using the Taylor series expansion; this facilitates expanding a time-varying function as a finite length polynomial and a bounded residue; the coefficients of the finite length polynomial are estimated in a time interval small enough so that they can be assumed to be constant within that interval. A novel experiment is designed using a two-link mechanical manipulator to investigate the proposed algorithm experimentally. Simulation and experimental results validate the proposed new adaptive control algorithm; we discuss these results and also give some future research directions.
Finite Element Stress Analysis of Bolted Joint and an Estimation of Axial Bolt Force
Authors: Sawa Toshiyuki , Yasui Hajime , Suzuki Yoshihito , Nakayama Takaki
Published: May 2008

An estimation of actual axial bolt force ill bolted joints is difficult. In practice, supersonic transducers have been used to measure the axial bolt force. However, the method is complicated and the accuracy for measuring the axial bolt force of bolts with shorter clamping length and the smaller nominal diameter is worse. It is necessary to develop a simple method to estimate the axial bolt force more accurately in practice. The displacement at the bolt head is proportional to the axial bolt force. Thus, when the relationship between the displacement and the axial bolt force is obtained, the bolt force is estimated as an inverse problem by using the bolt head displacement measured by a laser displacement transducer. In order to obtain the relationship between the displacement at the bolt head and the axial bolt force, finite element calculations were carried out. The effects of the friction coefficient between the contact surfaces of the bolt head and the clamped parts and the thickness of the clamped parts (hollow cylinder) are examined on the bolt head displacement by the FEM. As a result, the relationship between tile displacement and the axial bolt force was found to be linear by the FEM calculations. Then, the measurements of the bolt head displacement were carried out and the axial bolt force was measured by strain gauges attached at the bolt shank. By using the measured displacement and the relationship between the displacement and axial bolt force, the axial bolt force was estimated. The estimated values of the axial bolt force were in fairly good agreements with those measured by the strain gauges. It can be concluded that the method is available for measuring the axial bolt forces in bolted joints accurately.
Optimum Input for System Identification for Systems With Actuator Saturation Using Genetic Algorithms
Authors: Schoen Marco P. , Chinvorarat Sinchai , Schoen Gerhard M.
Published: May 2008

This paper presents an efficient implementation of constraint optimum input design for on-line system identification for systems exhibiting actuator saturation. The constraint optimal input is calculated recursively based on the imminent available information content in the inverse correlation matrix of the data. The new input is computed one step ahead of time with a predictive filter so that it will increase the information content in the inverse correlation matrix. The information content is maximized with help of a simple genetic algorithm. A numerical example indicates superiority of the proposed method over the traditional method where white gaussian noise is used as the input.
Intelligent Monitoring and Control of Industrial Processes Through the Internet
Authors: Tang Poi Loon , de Silva Clarence W. , Wang George
Published: May 2008

This paper presents a framework for developing a universal network infrastructure that would allow web-based monitoring and control of industrial processes, research facilities, and academic experiments. Internet technology is used here for its versatility, wide availability, and relative low cost. The main element of the infrastructure is a web-server, which connects to multiple control-servers, which in turn are connected to various processing modules within a local industrial facility, Since the web-server is the system centerpiece, which provides smooth information flow, a robust, intelligent, and autonomous scheduling scheme is required. Once such infrastructure is established, remote users in an academic or research environment, or in an industrial environment will be able to carry out a variety of tasks including experiments, monitoring and supervision, process scheduling and reconfiguration, using a web-browser. The flexibility and modularity of the developed networked infrastructure provide the rationale for implementing a multi-level hierarchical monitoring and control structure for a process. The usefulness of such a hierarchical structure is demonstrated through an application example on an industrial fish processing machine, which incorporates intelligent adaptive control.
Estimation and Identification of Mass-Spring-Dashpot Systems Using Multiple-Model Adaptive Algorithms
Authors: Asl Sajjad Fekri , Athans Michael , Pascoal Antonio
Published: May 2008

We present performance evaluations of different configuration for state estimation and identification of a complex Mass-Spring-Dashpot (MSD) system using Multiple-Model Adaptive Estimation (MMAE) algorithms. The algorithms compare two distinct MMAE strategies using either constant-gain or time-varying-gain Kalman filters to identify the correct model of the MSD system. Simulation results, for a variety of noisy measurement assumptions, illustrate the behaviour of the MMAE algorithms which are robust to mass uncertainties.
Fuzzy Logic Based Intelligent Control and Optimal Control of a Rotary Inverted Pendulum System
Authors: Garg Devendra P. , Jain Piyush
Published: May 2008

In this paper a fuzzy logic based control strategy has been applied to balance an inverted pendulum. An inverted pendulum in itself is a highly unstable system since there is always some external disturbance present that makes it to fall. Therefore, to maintain it in an upright position, a control input is needed, that could be in the form of torque, moment or force. Here an inverted pendulum with a rotary arm is chosen for study. The arm is driven in the direction of fall of the pendulum. This action attempts to stabilize the pendulum in the upright configuration. The fuzzy control action controls the torque applied to the actuator and thus controls the pendulum. A fuzzy inference system is constructed using Matlab. This is used to compute the output torque for a given set of angle and velocity. The same system is subjected to a Quadratic Optimal Control scheme, and the simulation results obtained from the fuzzy control system and Linear Quadratic Regulator control (LQR) scheme are compared.
A Forward Approach for Helicopter Track and Balance
Authors: Wang Shengda , Danai Kourosh
Published: May 2008

A method of helicopter track and balance is introduced that uses a forward-model to search for the appropriate blade modifications. This method uses an interval model to represent the ranges of effects of blade modifications on helicopter vibration, instead of exact values, in order to cope with the stochastic nature of aircraft vibration. The coefficients of the interval model are initially defined according to sensitivity coefficients between the blade modifications and helicopter vibration, but they are subsequently updated after each tuning iteration to improve the model’s estimation accuracy. The effectiveness of the proposed method is demonstrated through a simulation model that represents experimental vibration measurements of Black Hawk helicopters.
In Search of a Suitable Control Policy for Intelligent Vehicle Suspensions
Authors: Goncalves Fernando D. , Ahmadian Mehdi
Published: May 2008

Many control policies, such as skyhook and groundhook control, are now being considered for intelligent vehicle suspensions. Past studies have shown the performance limitations of these policies, as well as others that have been considered for vehicle applications. The performance of three semi-active control policies were studied experimentally under steady-state and transient inputs. Experimental results were obtained using a quarter-car rig and a magneto-rheological damper. The commonly considered skyhook and groundhook control policies were employed and evaluated under a steady-state, or pure tone, input and a transient, or step input. An alternative control technique called “hybrid control,” which attempts to merge the performance benefits of skyhook and groundhook control was also considered. Peak-to-peak displacement and peak-to-peak acceleration were used to evaluate performance. The results indicate that while skyhook and groundhook can offer benefits to either the sprung or unsprung masses, hybrid control can offer benefits to both masses. The compromise inherent in both skyhook and groundhook is eliminated with the use of hybrid control. Both the steady-state and transient dynamics of the sprung and unsprung masses can be reduced below those of passive using hybrid control with an α of 0.5. This corresponds to equal contributions from skyhook control and groundhook control.
A Simulation Approach for Bubble Flow in a Glass Melter
Authors: Chang S. L. , Zhou C. Q. , Golchert B.
Published: May 2008

Combustion heat is used in glass furnaces to melt sand and cullet (scrap glass) into liquid glass to make products. The glass flow in a melter consists of solid particles of sand/cullet, liquid glass, and bubbles. Bubbles formed in the melting processes due to the glass reactions have strong impacts on glass quality and furnace efficiency. Smaller bubbles entrained in the liquid flow degrade the glass quality. Larger bubbles rise to the top of the melter and form a foam layer that impedes the radiation heat transfer from the combustion space and lowers the furnace efficiency. An Eulerian approach was developed to simulate the bubble flow in a glass melter. The approach divides bubbles into various groups and treats each group of bubbles as a continuum. The mass, momentum, and energy conservation equations of the bubble flow are derived to solve for local bubble properties. The approach was incorporated into a multiphase reacting flow computational fluid dynamics code that simulates overall furnace flows to evaluate the impacts of bubbles on glass quality and furnace efficiency.
Advanced Human Modeling for Impact Simulation
Authors: Yang King H. , Beillas Philippe , Zhang Liying , Lee Jong-Beom , Shah Chirag , King Albert I.
Published: May 2008

This paper summarizes component models of the human body, from head to foot, developed at WSU over the last decade. All of these models were validated against global response data obtained from relevant cadaveric tests. This report summarizes the capabilities and limitations of these models and points the direction for future developments.
CART Impact Recorder Data Analysis Using Mathematical Modeling
Authors: Weerappuli Para , Chiu Edwin , Barbat Saeed , Prasad Priya
Published: May 2008

This paper presents acceleration data of seventy-eight open-wheel, Indy car type, racecar impacts. These data were collected by the “Impact Sensor Program” conducted jointly by the Ford Motor Company and the Championship Auto Racing Teams (CART), Inc. The seventy-eight impacts consisted of forty-two side impacts, thirty rear impacts, three frontal impacts, and three rollover/flipping of cars. Related crash data were used as input to a CAE model of a racecar driver in a typical CART car to perform computer simulations of the impacts. This model was developed using MADYMO software, and was an enhanced version of one previously published. Enhancements to the model included accurate geometrical representations of the cockpit interior, the seat, and the energy-absorbing collar; a more realistic geometry of the driver’s head and an improved representation of the neck; a highly detailed model of the driver’s helmet; and improved contact algorithms to define the head-helmet, helmet-collar, and head-chin strap interactions. Additionally, data collected from twenty-six drivers were used to improve the seating posture of the driver in the model. Results of simulations performed established the validity of the model in predicting the potential injury risk to the drivers in the head and neck areas. Model predictions of injuries based on the “Head Injury Criterion” (HIC), the Injury Assessment Reference Values (IARVs) of upper neck forces and moments, and a biomechanical neck injury predictor compared well with the actual injuries sustained by the drivers. The model predictions of reversible concussions also compared well with results of recent brain injury risk studies. The present study shows that CAE modeling can be effectively used to predict potential injuries to racecar drivers involved in high “G” impacts, and that the model can be used to evaluate countermeasures to improve safety of CART cars.
Active Vibration Control of a Clamped Square Plate
Authors: Shimon Philip T. , Hurmuzlu Yildirim , Richer Edmond
Published: May 2008

In this paper, we sought to develop an efficient controller for vibration reduction in a fully clamped plate. We investigated three control methodologies (positive velocity feedback, sliding mode control, and H∞ control) and two types of actuators (an inertial actuator and a distributed strain actuator). These were used to develop five control architectures (the sliding mode controller was not implemented for the inertial actuator). Both theoretical and experimental studies were undertaken with varying results. The best theoretical results were obtained when sliding mode and H∞ control were used in conjunction with a distributed strain actuator. Experimentally, the H∞ controller using the distributed strain actuator outperformed the others.
Performance Enhancement of a Monogroove Heat Pipe With Electrohydrodynamic Conduction Pumping
Authors: Jeong S. I. , Seyed-Yagoobi J.
Published: May 2008

Electrohydrodynamic (EHD) conduction pump is a new concept which has been recently explored. Net pumping is achieved by properly utilizing the heterocharge layers present in the vicinity of the electrodes. This paper presents an innovative electrode design which provides pressure head on the order of 600 Pa per an electrode pair operated at 20 kV with less than 0.08 W of electric power. An EHD conduction pump consisting of six pairs was designed and installed in the liquid passage of a monogroove heat pipe. The EHD conduction pump drastically increased the heat transport capacity of the heat pipe. Furthermore, the EHD conduction pump provided immediate recovery from the dryout condition.
Nonlinear Control Techniques for the Atomic Force Microscope System
Authors: Fang Yongchung , Feemster Matthew G. , Dawson Darren M. , Jalili Nader
Published: May 2008

In this paper, three nonlinear control techniques are proposed for an atomic force microscope system. Initially, a learning-based control algorithm is developed for the microcantilever–sample system that achieves asymptotic cantilever tip tracking for periodic trajectories. Specifically, the hybrid control approach utilizes a combination of a learning-based feedforward term to compensate for periodic dynamics while hign-gain terms are utilized to account for non-periodic dynamics. An adaptive control algorithm is then developed to achieve asymptotic cantilever tip tracking for bounded tip trajectories despite uncertainty throughout the system parameters. Lastly, a nonlinear controller coupled with a nonlinear observer is designed to provide for asymptotic tracking and interaction force identification unders a set of assumptions.
Optimal Feedback Control of Precision Paraboloidal Shell Structronic Systems
Authors: Tzou H. S. , Ding J. H.
Published: May 2008

Paraboloidal shell of revolution is a common shell shape used in aerospace, telecommunication, dome structures and many other engineering applications. A structronic shell system is defined as an elastic shell bonded or laminated with piezoelectric sensors and actuators and it is governed by either in-situ or external control electronics. A closed-loop control system of paraboloidal shell structronic system consists of distributed sensors/actuators and controller coupled with the elastic paraboloidal shell. State equation for the paraboloidal shell structronic system is derived and optimal linear quadratic (LQ) state feedback control is implemented, such that the “best” shell control performance with the least control costs can be achieved. The gain matrix is estimated based on minimizing a performance criterion function. Optimal control effects are compared with controlled responses with other non-optimal PD control parameters. Control effects of sensor/actuator patches at different locations with same size are studied and compared; control effects for different natural modes are also investigated.
Experimental and Analytical Investigations of the Dynamic Response of Adhesively Bonded Single Lap Joints
Authors: Vaziri A. , Nayeb-Hashemi H.
Published: May 2008

Dynamic response of single lap joints, subjected to a harmonic peeling load is studied theoretically and experimentally. In the theoretical part, dynamic response of a single lap joint clamped at one end and subjected to a harmonic peeling load at the other end is investigated. Adherents are modeled as Euler-Bernouli beams joined in the lap area by a viscoelastic adhesive layer. Both axial and transverse deformations of adherents are considered in deriving the equations of motion. The effects of adhesive layer thickness, mechanical properties and its loss factor on the dynamic response of the joint are investigated. Furthermore, effects of defects such as a void in the lap area on the dynamic response of the joints are studied. The results showed that frequencies where peak amplitudes occurred were little dependent on the adhesive loss factor. However, peak amplitudes reduced for joints with a higher adhesive loss factor. Furthermore, the results indicated that for the joint geometries and properties investigated the system resonant frequencies were not affected by the presence of a central void covering up to 80% of the overlap length. In the experimental part, single lap joints were fabricated using 6061-T6 Aluminum. Adherents were joined together using Hysol EA 9689 adhesive film. Joints with various central voids were manufacture by removing adhesive film from the desired area of lap joints prior to bonding adherents. Dynamic responses of the joints were investigated using the hammer test technique. The system response was measured using both an accelerometer and a non-contact laser vibrometer. The natural frequencies of the joints obtained by using the laser vibrometer were very close to those obtained theoretically. However, natural frequencies obtained by using an accelerometer depended on the accelerometer location in the system, which was attributed to its mass contribution to the over all system mass. A central void covering less than 80% of the overlap length had little effect on the system resonance frequencies. This was in agreement with the theoretical results. In contrast, total system-damping ratios were a function of the void size. Joints without a void exhibited higher damping.
Dynamic Response Control of Piezoelastic Laminated Cylindrical Shells Under Hydrostatic Pressure
Authors: Liu Zhengxing , Li Hongyun
Published: May 2008

Based on classical laminated plate theory and Navier solutions, the control of the piezoelastic laminated cylindrical shell’s dynamic response under hydrostatic pressure is discussed in this paper. Considering the direct and inverse piezoelectric effects of piezoelectric materials and from Hamilton’s principle, the nonlinear dynamic equations of the piezoelastic laminated cylindrical shell are derived first. Using close circuit method, the charge enclosed in the piezoelectric sensor layer can be measured. Furthermore, the voltage applied on the actuator layer can be obtained based on the closed-circuit charge signal of the sensor and velocity negative feedback control algorithm. An active dynamic response control model of simply supported laminated cylindrical shells with piezoelectric sensor/actuator under various dynamic loads is established in this paper at last. Three types of loading conditions, namely sinusoidal distributed load, line load and moving point load, are considered in numerical examples to investigate the performance of the control model. The numerical results show that the active control model presented in this paper can suppress the vibration of the structure under dynamic loading effectively.
Cohesive Finite Element Based Modeling of Damage in Composite Materials
Authors: Kumar Rajesh S. , Talreja Ramesh
Published: May 2008

Damage in composite laminates affects its overall viscoelastic response. Constitutive equations have been developed for composite laminates considering a fixed damage state. A complete description, however, requires suitable damage evolution laws. This paper is focused on studying damage evolution in viscoelastic laminates using a cohesive finite element approach. A two dimensional, four nodded finite element is developed incorporating a rate-independent traction-displacement cohesive law. This element is used in conjunction with plane strain bulk elements behaving in a linear viscoelastic manner to simulate crack evolution between two existing transverse cracks in symmetric cross-ply laminates. The effects of loading strain-rate, ply constraint and initial crack density are studied. This study shows expected trends in the behavior and indicates the suitability of cohesive zone modeling to study damage evolution in viscoelastic composite materials.
On the Nonlinear Dynamic Behavior of a Rotor-Bearing System
Authors: Jing Jianping , Sun Yi , Xia Songbo , Feng Guotai
Published: May 2008

The nonlinear dynamic behavior of a rotor-bearing system is analyzed based on a continuum model. The finite element method is adopted in the analysis. Emphasis is given on the so called “Oil-Whirl phenomena” which might lead to the failure of the rotor system. The dynamic response of the system in unbalanced condition is approached by direct integration method and mode superposition method, it is found that a typical “Oil-Whirl phenomenon” is successfully produced. Furthermore, the bifurcation behavior of the Oil-Whirl phenomenon that is much concerned in recent nonlinear dynamics research is analyzed. The rotor-bearing system is also examined by the simple discrete model. Significant differences are found between these two models. It is suggested that a careful examination should be made in modeling such nonlinear dynamic behavior of the rotor system.
Interaction of Hydrodynamic and Heat Processes in Turbulent Separated Flows
Authors: Kozlov A. P. , Mikheyev N. I. , Molochnikov V. M. , Stinski G. V. , Zanko P. S.
Published: May 2008

Results of an experimental investigation of the mechanism of hydrodynamic and heat processes interaction in turbulent separated flows on the basis of combined measurements of instantaneous local values of longitudinal skin friction vector component, wall heat flux and fluctuating wall pressure are presented. New combined wall probe was used in the experiments. The following cases of 2D separated flows are studied: a flow over a lug, a flow in the wake behind a transversal cylinder located near a wall. Data on space-time interaction of the measured parameters is obtained. It is shown that a mechanism of this interaction in many respects is determined by interaction of large scale coherent structures of a shear layer with a wall. In order to study the mechanism simultaneous measurements of the wall parameters and parameters in the wall region are provided. Also conditionally averaged fields of velocity and temperature in a flow are obtained as well as their correlation with the parameters distribution in a local wall region. A physical model of hydrodynamic and heat interaction of these structures with a wall is suggested.
Impingement of Axisymmetric Under-Expanded Sonic Jets on a Flat Plate
Authors: Kim Byung Gi , Yu Man Sun , Cho Hyung Hee , Hwang Ki Young , Bae Joo Chan
Published: May 2008

An experimental investigation has been carried out to examine heat transfer characteristics of an axisymmetric, under-expanded, and sonic jet impinging on a flat plate. Distributions of recovery factor and the surface pressure on the flat plate have been obtained in detail. The ratio of nozzle exit pressure to the ambient pressure, i.e., under-expansion ratio ranges from 1.5 to 3.5 and the nozzle-to-plate distance is tested from 0.5 to 20.0 nozzle exit diameters. It has been found that the recovery factor varies from 0.35 up to over 1.25 depending on both parameters of interest within the present experimental range.
Computational Modeling of Enhanced Laminar Flow Heat Transfer in Viscoplastic Fluids in Corrugated-Plate Channels
Authors: Metwally Hossam M. , Manglik Raj M.
Published: May 2008

The enhanced heat transfer in laminar viscoplastic, shear thinning, Herschel-Bulkley fluid flows in sinusoidal corrugated-plate channels is investigated. With uniform-temperature plate walls, periodically developed flows are considered for a wide range of flow rates (10 ≤ Reg ≤ 700) and pseudoplastic flow behavior indices (n = 0.54, 0.8, and 1.0; the latter representing a Bingham plastic). The effects of fluid yield stress are simulated for the case where τy = 1.59 N/m2, representing a 0.5% xantham gum aqueous solution. Typical velocity and temperature distributions, along with extended results for isothermal friction factor ƒ and Colburn factor j are presented. The effect of the yield stress is found to be most dominant at low Reg regardless of the power law index n, and the recirculation or swirl in the wall trough regions is weaker than in the cases of Newtonian and power-law liquids. At higher Reg, the performance of the Herschel-Bulkley fluid asymptotically approaches that of the non-yield-stress power-law fluid. At low Reg, the yield stress increases ƒ by an order of magnitude and j is enhanced because of the higher wall gradients imposed by the plug-like flow field. The relative heat transfer enhancement, represented by the ratio (j/ƒ), and the role of the fluid yield stress and shear-thinning (or pseudoplastic) behaviors are also discussed.
Myofibroblast Activity in an Animal Model for Human Hypertrophic Scar
Authors: Affonce Derek A. , Sojka Erik S. , Van De Water Livingston , Sheridan Robert , Fowler Alex J.
Published: May 2008

Approximately 100,000 burn patients require hospital admissions each year in the United States. About 90% of those patients survive to face the long term consequences of burn injury [1]. The primary cause of long term disability in burn survivors is hypertrophic scarring. These thick, deforming scars physically impair movement and cause major psychological morbidity. Hypertrophic scarring is particularly severe in young children [2].
Effect of Thermal Properties on Heat Transfer in Cryopreservation and Cryosurgery
Authors: Han Bumsoo , Bischof John C.
Published: May 2008

Biological materials in both cryopreservation and cryosurgery are composed of various chemicals and experience a wide range of temperature change. Therefore, their thermal properties including specific heat, latent heat (including water/ice and eutectic phase change) and thermal conductivity are expected to change significantly during freezing/thawing. The effects of thermal properties on heat transfer in cryopreservation/cryosurgery were studied experimentally and numerically. Thermal properties of various biological aqueous solutions were measured over a wide temperature range (−150~30°C). To estimate the effect of thermal property changes on the heat transfer, numerical simulations of both cryopreservation (cooled from outside) and cryosurgery (cooled from inside) geometries were performed with constant and temperature-dependent properties. The results show that the constant-property case significantly under-predicts the heat transfer over the temperature-dependent-property case regardless of the geometry.
Investigation of In Situ Thermal Denaturation of Proteins in Dunning AT-1 Rat Prostate Cancer Cells Using FTIR and DSC
Authors: He Xiaoming , Wolkers Willem F. , Crowe John H. , Swanlund David J. , Bischof John C.
Published: May 2008

In this study, the in situ protein denaturation in Dunning AT-1 rat prostate cells was studied using FTIR and DSC. The denaturation information from FTIR showed a shift from α helix (amide-I band at 1655cm−1) to β sheet (amide I band at 1620 cm−1). The relative beta sheet area change between 20 °C and 70 °C was used to dynamically scale the thermal denaturation process during heating at 2 °C/min. DSC scans (at scanning rates of 2°C/min and 5°C/min) of the heat flow due to protein denaturation were recorded from 20 °C to 70 °C. The range over which protein denaturation occurs (from 45 °C to 70 °C) was consistent in both studies. By calorimetric experiments with DSC, the enthalpy change during protein denaturation was found to be 27.3±4.0J/g J/g and 25.9±0.5J/g, respectively. In addition, the activation energy and frequency factor were measured by kinetic experiments with both DSC and FTIR. A first order irreversible Arrhenius model was fit to the kinetic data using a flexible tolerance method. The activation energy (E) and frequency factor (A) between 20–70 °C was found to be 107.8kJ/mole and 3.4·1014 l/s for the FTIR study and 120.9kJ/mole and 3.6·1016 l/s for DSC analysis at a scanning rate of 2°C/min, respectively. At a scanning rate of 5°C/min, the DSC results gave an activation energy of 144.5kJ/mole and a frequency factor of 4.1·1020 l/s.
An Experimental Study of Local Heat Transfer Distribution Between Blockages With Holes in a Rectangular Channel
Authors: Moon S. W. , Lau S. C.
Published: May 2008

Experiments have been conducted to study heat transfer between two blockages with holes and pressure drop across the blockages, for turbulent flow in a rectangular channel. Average heat transfer coefficient and local heat transfer distribution on one of the channel walls between two blockages, and overall pressure drop across the blockages were obtained, for nine different staggered arrays of holes in the blockages and Reynolds numbers of 10,000 and 30,000. For the hole configurations studied, the blockages enhanced heat transfer by 4.6 to 8.1 times, but significantly increased the pressure drop. Smaller holes in the blockages caused higher heat transfer enhancement, but larger increase of the pressure drop than larger holes. The heat transfer enhancement was lower in the higher Reynolds number cases. Because of the large pressure drop, the heat transfer per unit pumping power was lower with the blockages than without the blockages. The local heat transfer was lower nearer the upstream blockage, the highest near the downstream blockage, and also relatively high in regions of reattachment of the jets leaving the upstream holes. The local heat transfer distribution was strongly dependent on the configuration of the hole array in the blockages. A third upstream blockage lowered both the heat transfer and the pressure drop, and significantly changed the local heat transfer distribution.
Measurement of Cryoprotectant Concentration Using MRI in Pseudobiological Tissues and Determination of Diffusivity Based on Inverse Problem Analysis
Authors: Ishiguro Hiroshi , Kai Takanori , Ogawa Kuniyasu
Published: May 2008

Transient one-dimensional distribution of cryoprotectant concentration in pseudobiological tissues (agar) was measured noninvasively using magnetic resonance imaging (MRI). Cryoprotectants were dimethyl sulfoxide (DMSO) and glycerol, common cryoprotectants penetrating cells. Attenuation of MRI image intensity due to volumetric fraction of solution and relaxation times was also investigated. Apparent diffusivity of each cryoprotectant as a function of agar concentration was determined from the inverse problem analysis. The diffusivity decreased with an increase in agar concentration. This method was also applied to the liver tissues of chicken.