bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Characterization of a Magnetically Driven Valveless Micropump for Drug Delivery
Authors: Zhou Y. , Amirouche F. , Chen L.
Published: July 2009

Micropump, an actuation source to transfer the fluid from reservoir to the target place with accuracy and reliability, plays an important role in microfluidic devices. A broad range of micropump applications in biomedical fields are found in the fluid fine regulation and precise control systems for implantable drug delivery, chemical and biological detection, as well as blood transport in cardiology system. A polydimethylsiloxane (PDMS) magnetic composite membrane based on microfabrication with dimensions of 6 mm and 65 μm in diameter and thickness respectively, is employed to actuate a proposed micropump. In micro pumping operation, the fluid flow effects on the actuation and dynamic response of an oscillating membrane are curial to the design of the micropump. Therefore, the resonant frequency of this micro device is estimated considering the added mass and fluid damping to understand the behaviors of the valveless micropump. In this study, the membrane actuation is implemented by a miniaturized electromagnet, which provides an external time-varying magnetic field. The magnetic force on the membrane is proportional to the gradient of the magnetic field and the magnetization of the micro particles embedded in the membrane. The alternating attractive and repulsive magnetic forces on this composite membrane are computed by Finite Element Analysis (FEA). The basic design issues of the electromagnetic actuator involving air gaps, input current signals, and distribution of magnetic flux in the magnetic circuit are presented. Moreover, the magnetic-structure coupling analysis is conducted to determine the maximum deformation and stresses on the membrane, which result from the action of these magnetic forces. Finally, frequency-dependent flow rate of a dual-chamber configuration micropump has been studied. The pumping rate increases almost linearly with the excitation frequency at low ranges and there exists resonant frequencies at which the flow rate will reach a maximum value. After the flow rate peaks, the pumping rate decreases sharply along with the actuating frequencies. The maximum flow rate for the dual-chamber remains at 27.73μl/min under 0.4 A input current with an excitation frequency of 3 Hz. For comparison, a single-chamber micropump reaches a maximum flow rate of 19.61μl/min with a resonant frequency of 4.36 Hz under the same condition.
Stage-Gate Process for the Development of Medical Devices
Authors: Pietzsch Jan B. , Shluzas Lauren A. , Paté-Cornell M. Elisabeth , Yock Paul G. , Linehan John H.
Published: July 2009

The medical device development process has become increasingly complex in recent years. The advent of new technology concepts, stricter regulatory requirements, and the ever increasing importance of reimbursement decisions for successful device commercialization require careful planning and strategy-setting, coordinated decisions, and consistent, rigorous business processes. The design and implementation of such processes, often captured in development models and accompanying standard operating procedures, have become a key determinant of the success of device commercialization. While various models may exist in the device industry, no comprehensive development model has been published. This paper reviews existing model representations and presents a new comprehensive development model that captures all aspects of device development and commercialization from early-concept selection to postmarket surveillance. This model was constructed based on best-practice analysis and in-depth interviews with more than 80 seasoned experts actively involved in the development, commercialization, and regulation of medical devices. The stage-gate process includes the following five phases: (1) initiation - opportunity and risk analysis, (2) formulation - concept and feasibility, (3) design and development - verification and validation, (4) final validation - product launch preparation, and (5) product launch and postlaunch assessment. The study results suggest that stage-gate processes are the predominant development model used in the medical device industry and that regulatory requirements such as the food and drug adminstration (FDA’s) Quality Systems Regulation play a substantive role in shaping activities and decisions in the process. The results also underline the significant differences between medical device innovation and drug discovery and development, and underscore current challenges associated with the successful development of the increasing number of combination products.
Optimum Design of Control System Compensators By Geometric Programming
Authors: Bohn E. V.
Published: July 2009

A process of condensation is used to develop a geometric programming approach to the necessary conditions for a constrained optimum in an elementary way. Special features of geometric programming not found in other optimization procedures and which offer significant advantages in the design of optimum compensators are developed. Compensator design is formulated as an optimum pole placement problem subject to a time delay response constraint. The geometric programming approach results in simple explicit equations for the optimum compensator parameters.
Identification of Lower Extremity Dynamics During Snow Skiing
Authors: Lee C. W. , Mote C. D.
Published: July 2009

Severity of the skiing environment can be interpreted only through the response of the lower extremity to the excitation of the environment. Identification of a linear, four degree of freedom, lower extremity ski torsion model was undertaken. A new procedure is introduced for filtering the deterministic trends from the random torsion data measured between the boot and ski during skiing. Trend removal is necessary for identification. The objective function for the identification was the square of the difference between the spectrum of the trend-removed torsion data and the spectrum of the model torsion. Following identification, the model responses predicted during two authentic skiing falls were computed, thus permitting a comparison of their relative severity.
A Describing Function for Dynamic Forces in Single Degree-of-Freedom Mechanisms
Authors: Allen R. R. , Rozelle D. M.
Published: July 2009

In a single degree-of-freedom mechanism, a generalized force is produced by elastic, dissipative, and inertial effects. This force may be expressed as a power series in the mechanism’s generalized velocity where the coefficients are functions of the generalized displacement. Approximating the coefficients by their Fourier series expansions produces a describing function which is rapidly convergent and provides substantial computational and analytical advantages over using the exact equations. This describing function permits efficient time-domain simulation of mechanism dynamics and produces an analytical expression for the spectral content of the mechanism dynamic force. Generation and application of the describing function is illustrated by a numerical example.
Responses of Continuous, Elastically Supported Beam Guideways to Transit Loads
Authors: Wilson J. F. , Barbas S. T.
Published: July 2009

Solutions for nondimensional dynamic response histories are formulated for an undamped, continuous, Bernoulli-Euler beam resting on discrete, evenly-spaced, equal elastic supports. Responses depend on: The distribution of the constant force loads; a dimensionless load speed parameter; and the ratio of support stiffness to beam stiffness. Peak midspan moments and deflections are calculated over a wide range of system parameters for several beam configurations. Results are that the extreme end spans have the peak dynamic responses; that these responses increase as the relative support stiffness increases; and responses may become unbounded. Experimental measurements complement the calculations. Results are applicable to the design of cable-stayed guideways for advanced transit systems.
Cross-Coupled Biaxial Computer Control for Manufacturing Systems
Authors: Koren Yoram
Published: July 2009

Biaxial control systems for generating predetermined paths under load disturbances, such as encountered in NC and CNC systems for machine tools, are conventionally designed such that the control of each axis is independent of the other. The present paper is concerned with providing cross-couplings for biaxial control systems, whereby an error in either axis affects the control loops of both axes. An algorithm for a cross-coupled control system is presented, and the performance of the cross-coupled system is mathematically analyzed and compared with the conventional CNC system having individual axis control. It is shown that cross-coupling between axes improves the contour accuracy while the velocity response of each axis is only slightly reduced. Although the proposed cross-coupled system requires additional hardware for implementation with an NC system, operation with a CNC-based system requires only software modifications to the system control program.
A Mathematical Model for the Evaluation of Injection Molding Machine Control
Authors: Shankar A. , Paul F. W.
Published: July 2009

This paper presents the development of a deterministic nonlinear lumped parameter mathematical model useful for the study and design of polymer injection molding machines and their associated controllers. The mathematical model was simulated on a digital computer and the results compared with experimental measurements taken in an existing injection molding machine. A comparison of these results showed that the developed mathematical model adequately predicts the transient behavior of averaged machine and mold variables. The resulting model is useful for control system design, machine parameter selection, and model redesign purposes.
Experimental Evaluation of the Preview Servo Scheme for a Two-Axis Positioning System
Authors: Tomizuka M. , Dornfeld D. , Bian X.-Q. , Cai H.-G.
Published: July 2009

A preview servo scheme for position and velocity control is implemented on a two-axis welding table. The Kalman filtering theory is used to estimate the velocity from position measurements, and a cornering scheme is proposed to attain smaller path errors at sharp corners. The experimental results show that the preview-servo scheme with the Kalman filter and corner preview features is suitable for on-line control of the welding system.
On a Magnetic Damper Consisting of a Circular Magnetic Flux and a Conductor of Arbitrary Shape. Part I: Derivation of the Damping Coefficients
Authors: Nagaya Kosuke , Kojima Hiroyuki
Published: July 2009

Theoretical results for finding the damping coefficients of a magnetic damper consisting of a circular magnetic flux and an arbitrarily shaped conductor have been obtained. In the analysis the exact solution in polar coordinates for the governing equation of the electromagnetic fields is utilized. The boundary condition for arbitrarily shaped boundaries of the conductor is satisfied directly by means of the Fourier expansion collocation method. To discuss the accuracy of the present approximate results, the analysis also has been performed on damper consisting of a circular flux and a circular conductor. The comparison between the present results and the exact ones for the typical damper shows very good agreement.
A Dynamic Model of a Pressure Swing Oxygen Generation System
Authors: Beaman J. J.
Published: July 2009

A full system model for oxygen generation from a pressure swing adsorption process is developed. The system under study has two zeolite packed molecular sieve beds which are cycled with high and low pressure in order to produce oxygen enriched air. These On-Board Oxygen Generation Systems (OBOGS) are to be used for the generation of aircraft crew breathing requirements. These units are much smaller in scale than present industrial systems and are called on to respond to variable demand. These special requirements have led to a reliable computer-based model to simulate the relatively fast transient performance of OBOGS. Besides the two zeolite beds, the system consists of a rotary valve used to cycle the beds, purge orifice, and breathing plenum. The computerized model predictions compare favorably with experiment. The model is presently being used in design and control synthesis studies.
An Equivalent Linearization Algorithm for Nonlinear System Limit Cycle Analysis
Authors: Abel S. G. , Cooperrider N. K.
Published: July 2009

An approach for determining the characteristics of limit cycles in higher order systems with multiple nonlinearities is described. This method utilizes sinusoidal input describing functions to convert the nonlinear problem to an eigenvalue problem. A search procedure employing eigenvalue derivatives finds limit cycle conditions, when they exist. This technique is relatively efficient and reliable and able to treat problems with strong nonlinearities such as Coulomb friction or relays. Two applications are presented, a mechanical servo positioner system and a railway bogie dynamics problem. Comparison of results with simulation is made.
Dynamic Load Carrying Capacity of Mechanical Manipulators—Part II: Computational Procedure and Applications
Authors: Wang L. T. , Ravani B.
Published: July 2009

A computational procedure is presented for obtaining numerical solutions to the trajectory optimization problem associated with synthesizing robot dynamic trajectories with maximum load carrying capacities. The applications of the procedure and the problem formulations given in Part I of this paper to synthesizing time-optimal robot motions and classification of multi-degree-of-freedom robot manipulators are also investigated.
Sensitivity Reduction by State Derivative Feedback
Authors: Haraldsdottir A. , Kabamba P. T. , Ulsoy A. G.
Published: July 2009

This paper shows that the sensitivity of state feedback control systems can be reduced by additional state derivative feedback, for a fixed closed loop eigenstructure. The price of this sensitivity reduction is in general noise response amplification. Two indices which quantify stability robustness and response sensitivity are given for time invariant continuous time and discrete time systems, together with an index of response to disturbances and noise. Closed form expressions for the gradients of these indices are given. A two step design procedure is proposed which consists of first selecting a closed loop eigenstructure, then minimizing one of the sensitivity indices under a magnitude constraint on the noise response. Examples are given to illustrate this original design procedure.
The Effect of Leakage on Railroad Brake Pipe Steady State Behavior
Authors: Abdol-Hamid K. , Limbert D. E. , Chapman G. A.
Published: July 2009

A mathematical model for pneumatic transmission lines containing leakage is developed. This model is used to show the effect of leakage size and distribution on the steady state behavior of the brake pipe on a train brake system. The model equations are solved using the implicit finite difference scheme without neglecting any terms. The model is presented in a nonlinear continuous network form, consisting of N sections. Each of the network sections represents one car and may contain one leakage. A computer program was developed to solve the model equations. This program is capable of simulating a train with cars of various lengths and takes a minimum amount of computation time as compared with previous methods. Through analysis and experimentation, the authors have demonstrated that pressure gradient and inlet flow rate are very sensitive to leakage locations as compared with leakage size. The results, generated by the mathematical model, are compared with the experimental data of two different brake pipe set-ups having different dimensions.
Robust Controller Synthesis of Multivariable System Subjected to Noises and Nonlinear Time-Varying Plant Perturbations
Authors: Hsiao Feng-Hsiag , Chen Bor-Sen
Published: July 2009

A new robust stability criterion is developed to guarantee the stability of the feedback systems subjected to noises and nonlinear time-varying plant perturbations. The main contribution of this paper is an extension of the results of robust stability for the class of feedback systems containing nonlinear time-varying plant perturbations to the class of systems with unstable plants and noises. The generally parameterized stabilizing controller, advanced by Youla et al., is combined with Schur function (class S) to synthesize the robust stabilizers of the feedback systems subjected to noises and nonlinear time-varying plant perturbations.
Modeling and Conventional/Adaptive PI Control of a Lathe Cutting Process
Authors: Tomizuka M. , Zhang S.
Published: July 2009

A mathematical model for predicting dynamics between the feedrate and cutting force in the lathe cutting process is presented. The model comes from combinations of a parameter identification technique and geometrical consideration for chip thickness time variation. The model prediction of transient responses is in good agreement with the experimental results. The model is used for tuning a PI controller for regulating the cutting force as well as to show performance limitations of the conventional PI controller. A simple adaptive control scheme that makes use of the model structure is proposed. Experimental results from laboratory evaluation of the proposed controllers are presented.
A Sequential Integration Method
Authors: Chang Liang-Wey , Hamilton James F.
Published: July 2009

This paper presents a method for simulating systems with two inertially coupled motions, i.e., a slow motion and a fast motion. The equations of motion are separated into two sets of coupled nonlinear ordinary differential equations. For each time step, the two sets of equations are integrated sequentially rather than simultaneously. Explicit integration methods are used for integrating the slow motion since the stability of the integration is not a problem and the explicit methods are very convenient for nonlinear equations. For the fast motion, the equations are linear and the implicit integrations can be used with guaranteed stability. The size of time step only needs to be chosen to provide accuracy of the solution for the modes that are excited. The interaction between the two types of motion must be treated such that secular terms do not appear due to the sequential integration method. A lumped model of a flexible pendulum will be presented in this paper to illustrate the application of the method. Numerical results for both simultaneous and sequential integration are presented for comparison.
Lumped and Distributed Parameter System Identification Via Shifted Legendre Polynomials
Authors: Mohan B. M. , Datta K. B.
Published: July 2009

In this paper, one shot operational matrix for repeated integration of the shifted Legendre polynomial basis vector is developed and double-shifted Legendre series is introduced to approximate functions of two independent variables. Then using these, systematic algorithms for the identification of linear time-invariant single input-single output continuous lumped and distributed parameter systems are presented. Illustrative examples are provided with satisfactory results.
A Dynamic Model of the Flapper-Nozzle Component of an Electrohydraulic Servovalve
Authors: Lin S. J. , Akers A.
Published: July 2009

An analysis has been conducted on the flapper-nozzle stage of a two-stage electrohydraulic controller that has been specifically designed to be a stable, stand-alone dynamic system. Calculations performed on equilibrium control pressures, stage gain, and frequency response characteristics agree with values obtained experimentally to within close limits. The analysis applies generally to a flapper-nozzle combination using any set of dimensions convenient for the designer. Flow-pressure equations and flapper dynamic properties have also been given to enable the designer to obtain full design characteristics.
A Correlation Between Steady-State and Dynamic Response of a Counterflow Heat Exchanger
Authors: Kawata Seiichi , Kanoh Hideaki , Masubuchi Masami
Published: July 2009

It is shown that the steady-state response such as temperature efficiency and number of heat transfer units have a direct relation with the dynamic response such as stability region of the PI control system. These relations are also explained by showing the physical meaning of the spatial weighting function presented by the authors. The theoretical results have also been confirmed by experiments. It is emphasized that the heat exchanger should be designed to have the excellent performance both at the steady state and the dynamic state.
Steady State Techniques in Creep Force Estimation: Results From Full Scale Tests of the SOAC Vehicle on a Roller Rig
Authors: Imtiaz-ul-Haque  , Law E. Harry
Published: July 2009

Steady state forced response tests of the SOAC vehicle were conducted on the roller rig (Roll Dynamics Unit) at the U.S. DOT/Transportation Test Center. This paper presents the test procedures, the results of the tests, and the analysis procedures developed for the estimation of the creep coefficients. Results of the estimates are compared with theory and possible reasons for discrepancies are discussed.
Dynamic Analysis and Measurement of Sloshing of Fluid in Containers
Authors: Barron R. , Chng S. W. Roy
Published: July 2009

Fluid sloshing problems in circular containers are studied by both theoretical and experimental methods. A circular cylindrical container, with various levels of fluid, attached to a low frequency suspension is analyzed by means of the method of asymptotic expansion. Experimental studies, in the form of resonance and transient vibration tests have been conducted on a test rig. A theoretical analysis is applied to a mathematical model of the test rig. The equations of motion are simulated by a digital simulation method, for both linear and nonlinear conditions. Results show parametric resonance effects of the fluid wave height and horizontal fluid force waveforms. During transient motion the fluid damping and frequency characteristics are nonlinear. The additional dynamic force on the container walls, due to sloshing of fluid, is approximately 45 percent of the applied horizontal excitation force on the system.
Identification of the Damping Law of an Electro-Rheological Fluid: A Sequential Filtering Approach
Authors: Stanway Roger , Sproston John , Firoozian Riaz
Published: July 2009

In this paper an approach is described to identifying the damping law of an electro-rheological (ER) fluid in vibration. The damping law is obtained by employing a nonlinear, sequential filter to estimate the parameters associated with an nth-power velocity model of the damping mechanism. To establish experimental requirements the application of the technique is first examined under controlled conditions in a numerical study. The feasibility of the approach is then demonstrated in an experimental study to identify the damping law of a prototype ER damper.
Four-Joint Redundant Wrist Mechanism and Its Control
Authors: Yoshikawa Tsuneo , Kiriyama Shigeo
Published: July 2009

It is known that conventional three-joint wrists of robot manipulators have two conical regions of degeneracy in which the ability of the wrist to orient the end-effector is poor, A four-joint wrist mechanism is proposed in this paper as a means of overcoming this degeneracy problem. The manipulating ability of this wrist with respect to the end-effector orientation is analyzed using the manipulability measure. A pseudoinverse control algorithm for this redundant wrist mechanism is developed and its effectiveness is shown by experiments.
Analysis and Synthesis of Discrete-Time Repetitive Controllers
Authors: Tomizuka Masayoshi , Tsao Tsu-Chin , Chew Kok-Kia
Published: July 2009

Repetitive control is formulated and analyzed in the discrete-time domain. Sufficiency conditions for the asymptotic convergence of a class of repetitive controllers are given. The “plug-in” repetitive controller is introduced and applied to track-following in a disk-file actuator system. Inter-sample ripples in the tracking error were present when the “plug-in” repetitive controller was installed. The performance is enhanced, however, when the zero-holding device is followed by a low-pass filter or replaced by a delayed first-order hold.
Nonlinear Model Tracking by Robot Manipulators
Authors: Skowronski J. M.
Published: July 2009

The modified model reference adaptive control (MRAC) technique is used to make a highly nonlinear and coupled n DOF robot manipulator with uncertain parameters to follow a prescribed model in a real time and on bounded work-space. The time and accuracy of the tracking may be stipulated. The corresponding adaptive laws are given in terms of exactly integrable simple linear equations and the signal adaptive feedback controller is specified in a closed form, thus making the onboard computer to work as a calculator. An RP-manipulator example illustrates the results.
Modeling and Control of Multiple Web Spans Using State Estimation
Authors: Young G. E. , Shelton J. J. , Kardamilas C.
Published: July 2009

Web processing systems rely on accurate lateral positioning to achieve high processing speeds and improved product quality. Due to physical constraints in some processing lines placement of the edge sensor near the web guide is not possible. As a result, large lateral oscillation and/or web instability have been observed. A new model is developed for lateral web dynamics. Experimental verification has justified the structure of the model. A parameter estimation scheme is used to tune the model for imperfections not originally incorporated. State estimation is then used to predict lateral web position on a downstream sensor. Desirable control is achieved and is further improved with the use of the feedforward sensor. Predicted and experimental results are compared.
Algorithms for Degree of Controllability of Uncertain Mechanical Systems
Authors: Guttalu R. S. , Skowronski J. M.
Published: July 2009

The retrograde (or backward-time evolution) point mapping numerical method introduced by C. S. Hsu is employed in conjunction with the Liapunov type sufficient conditions to determine the boundary of recovery region (or region of controllability with given control) or the degree of controllability for mechanical systems. The computational algorithm developed here is applicable to highly nonlinear and coupled mechanical systems. In addition, these systems are subjected to uncertainty in some parameters. As an example, the theory developed here is illustrated on a single degree of freedom Duffing system.
Implementing Air Combat Guidance Laws
Authors: Merz A. W.
Published: July 2009

The one-on-one air combat problem has been studied by both theoreticians and pilots, beginning with the “dogfights” of World War I. Since that time, aircraft and weapon capabilities have vastly increased, but no comparable improvements in pilot tactics or maneuver algorithms have been acknowledged. The advent of new sensors and onboard computing capabilities suggest that the theory of differential games may be applied to this problem. A review of the work done in this field is followed by discussion of a practical method of convincing the pilot of the validity of this theory.
Estimating Euclidean Reachable Sets for Retarded Functional Differential Equations With Bounded Delay
Authors: Gayek J. E.
Published: July 2009

A Lyapunov-like theorem is presented for finding an upper estimate on the set of points in Rn which are reachable from an initial set of continuous functions φ:[−r, 0] → Rn which satisfy sup[−r, 0]|φ(s)| < δ where the dynamics of the system are governed by n first order retarded functional differential equations with bounded delay subject to bounded control. An example is given for a second order delay-differential equation.
An Eclectic Approach to the State Feedback Control of Nonlinear Dynamical Systems
Authors: Z˙ak S. H.
Published: July 2009

This paper examines the problem of robust state-feedback stabilization of a class of nonlinear multi-input dynamical systems. Four approaches to the problem are investigated: the variable structure control (VSC) method, the high-gain feedback technique, the feedback linearization algorithm, and finally the deterministic approach to the control of uncertain systems. It is shown that each design method can lead to a controller such that the closed-loop system exhibits a sliding mode property. The sliding mode is a desirable property since it results in a robust control. The analysis is illustrated by means of a simple numerical example.
Recursive Lyapunov Functions
Authors: Olas Andrzej
Published: July 2009

The paper presents the concept of recursive Lyapunov function. The concept is applied to investigation of asymptotic stability problem of autonomous systems. The sequence of functions {Uα(i)} and corresponding performance measures λ(i) are introduced. It is proven that λ(i+1) ≤ λ(i) and in most cases the inequality is a strong one. This fact leads to a concept of a recursive Lyapunov function. For the very important applications case of exponential stability the procedure is effective under very weak conditions imposed on the function V = U(0). The procedure may be particularly applicable for the systems dependent on parameters, when the Lyapunov function determined from one set of parameters may be employed at the first step of the procedure.
Model Tracking Control of Hamiltonian Systems
Authors: Flashner H. , Skowronski J. M.
Published: July 2009

A new approach is presented for deriving control laws for dynamic systems that can be formulated by Hamilton’s canonical equations. The approach uses the complete nonlinear equations of the system without requiring linearization. It is shown that the error equations, between the system and a Hamiltonian model to be followed, can be described by Hamilton’s canonical equations. Using the concept of diagonal set in the cartesian product of the system and the model states, a control law is derived using the Liapunov stability approach. The resulting control law allows tracking within a stipulated precision, and also with a finite time horizon. To demonstrate the method, a control law is derived for a two degree of freedom manipulator, designed to follow a linear plant. Simulation studies show fast convergence of the state error for a large angle motion maneuver.
Development of Photoinitiated Nitric Oxide Releasing Polymer Films for Controlled Drug Delivery
Authors: Smeenge D. M. , Frost M. C.
Published: July 2009

Nitric Oxide (NO) is small, free radical gas that has been shown to have a wide variety of physiological functions, including the ability to hinder tumor angiogenesis at high, but non lethal, concentrations. Previous work suggests that if NO could be effectively delivered in vivo to tumors of patients currently undergoing chemotherapy treatments at the appropriate levels, less damaging chemotherapy treatments could be used against cancer. This could increase the overall survivability of cancer patients, especially in those prone to the harmful effects of chemotherapy: children, elderly, and those of weak immune systems. If NO is especially successful at preventing and eliminating tumor growth, angiogenesis, and carcinogenesis the need for stressful chemotherapy treatments could be eliminated altogether. This project is focused on developing novel photosensitive NO donors that can be incorporated into polymeric systems and used in a fiber optic drug delivery system. Development of these NO-releasing polymers will allow continued investigation of NO's role in tumor death by precisely controlling the surface flux of NO that cells are exposed to. Generating specific surface fluxes of NO from polymer films has been demonstrated by using polymer films that contain photoinitiated NO donors, prepared by synthesizing S-nitrosothiol (RSNO) derivitized polymer fillers that are blended into hydrophobic polymers and cast into a film. These films generate and sustain a surface flux of NO based on the wavelength and intensity of light used. Polymers releasing NO are more promising as an NO donor than simply injecting NO into samples because they allow for spatial and temporal control of NO delivery. The specific concentration of NO needed to produce desirable effects on tumor cells (i.e. apoptosis) is not known. Data will be presented that show the synthesis and NO-release properties of novel RSNOs based on the nitrosation of benzyl mercaptan thiols. Specifically, UV-Vis spectrum of benzyl mercaptan in toluene and S-nitrosobenzyl mercaptan after the addition of t-butyl nitrite will be presented. We are currently investigating the effects of varying NO-surface fluxes generated from photolytic NO donating polymer films on aortic smooth muscle cell cultures obtained from mice. Once we have established that we can quantitatively determine the effects of different levels of NO on the proliferation of smooth muscle cell cultures, work will begin to apply this methodology and these novel NO-releasing polymeric systems to begin investigating what durations and surface fluxes of NO are necessary to have tumorcidal effects on specific cancer cells.
An Efficient Quasi-2D Simulation of Waterhammer in Complex Pipe Systems
Authors: Duan Huan-Feng , Ghidaoui Mohamed S. , Tung Yeou-Koung
Published: July 2009

An efficient quasi-2D numerical waterhammer model for turbulent waterhammer flows has been previously developed for a single pipe system (reservoir-pipe-valve system). Basic boundary conditions, such as valves, reservoirs, and external flows, were also implemented. This paper extends this previously developed efficient scheme to a general model for a multipipe system. More specifically, an approach for matching the family of characteristic equations in each pipe at a junction of two or more pipes is proposed. In addition, the numerical stability conditions of the efficient scheme are investigated using the Von Neumann method. The resulting model is verified against experimental data and then applied to different complex systems involving pipes in series, branching, and network. Using this model, the effects of unsteady friction in complex pipe systems are examined and analyzed in this paper. From the case studies, it is found that the quasi-2D model is highly efficient, robust, and suitable for application to waterhammer problems in real complex pipe system.
Manufacturability Analysis Using Integrated KBE, CAD and FEM
Authors: Johansson Joel
Published: July 2009

Finite element analyses (FEA) are often used to test product properties virtually. The process of setting up FEA is many times manual and not strictly formalized; the assumptions made in those calculations highly depend on the analysts’ former experiences and gut feeling. Sometimes there exist parametric FEA-models, but they are hard to interpret for others than the developers. These parametric FEA-models are also highly inflexible. It is beneficial to formalize and automate the process of developing such calculations in order to automate the product development process for mature and variant-rich products where predictions and validations using FEA are demanded in the whole or parts of the design space. Making the automated FEA-models more flexible and more transparent makes them live longer and be more available for engineers that are not FEA-specialists. The FEA-specialists will have more time to solve general problems rather than focusing on instances of the product. In this paper, a proposal is made on how to integrate Knowledge Based Engineering (KBE), CAD and FEM to make the automation of FEA flexible, transparent, and easy to use. The method proposed includes the usage of an inference engine that handles knowledge objects that connect to auxiliary software applications. In the paper, an implementation example is presented where toolsets for the rotary draw bending of aluminium tubing are analyzed for manufacturability.
Modeling an Active Vehicle Suspension System With Application of Digital Displacement Pump Motor
Authors: Song Xubin
Published: July 2009

Vehicle suspension design can be simplified by using compressible fluid (CF) based struts. One single CF strut can provide both spring and damping force instead of two independent components of spring and shock absorber in a traditional vehicle suspension system. With the application of a digital displacement pump motor (DDPM) to modulate the fluid amount in CF struts, a hydraulic based active suspension can be developed. Each vehicle suspension corner (i.e., CF strut) can be linked to (at least) one cylinder of a multiple cylinder DDPM. Each cylinder has two poppet valves to allow exchanging flow between strut and accumulator. Those valves are actively controlled according to a properly designed control strategy. Thus DDPM can regulate the fluid flow to/from the CF struts to create a desired strut force at each suspension corner. This paper focuses on elaborating this novel active suspension using CFS and DDPM, and then presents a model that can well capture the macro-behavior of this new active suspension.
Research on Parametric Simulation Technology Based on Complicated Mechanism Design
Authors: Sun Wei , Han Qingkai , Li Xiaopeng , Wen Bangchun
Published: July 2009

A new method is proposed, which is the core of parametric simulation based on complicated mechanism design. Furthermore, the connotation of parametric simulation is affirmed and the flow of parametric simulation based on complicated mechanism design is put forward. At last, taking a parallel mechanism as example, the technology of parametric simulation proposed is applied to the simulation study used ADAMS, which consist of analyzing mechanism, parametric modeling, creating GUI, creating menu and parametric simulation. The practice indicates that the method is effectual.
Microprocessor-Based Robot Action Control Using Local Closed-Loop Approach
Authors: Chen Chao Hung , Lin Hsiung Cheng , Liu Ying Chu , Hsu Wei Chung
Published: July 2009

With increasing demand of robot applications in industry or other areas, the development of both reliable and low-cost robot action control system is getting much attention in recent years. This paper has proposed a local closed-loop based robot action control module using independent microprocessors. The robot action commands transmitted from PC via RS232 can be received by the individual authorized microprocessor. There are up to tens of modules to be operated for a variety of robot actions simultaneously and independently. Real world performance results are presented to demonstrate the effectiveness of the proposed approach in term of robust, simple, flexible and efficient performance.
A Second Generation of Numerical Implementation of Nonlinear Piezoelectric Models in Commercially Available Tools
Authors: Qidwai M. A. Siddiq , DeGiorgi V. G.
Published: July 2009

Domain switching based nonlinear behavior is characteristic of relaxor-type piezoelectric material such as PMN-PT single crystals. These materials offer significant device performance improvements over traditional polycrystalline piezoelectric materials such as PZT-5A. The promise of increased performance of these materials has led to work in development of constitutive characterizations so that material behavior under load and material failure mechanisms can be understood and predicted. However, there is a gap between development of such theoretical developments and in workable manifestations available as part of commercial finite element codes for use in device design. In the current work, the authors extend previously documented implementation of a macro-mechanical constitutive model which addresses domain switching, into a commercially available finite element code. A rate dependent version of the constitutive model has been successfully realized and used to reproduce a variety of piezoelectric constitutive behaviors.
Position and Orientation Characteristic Equation for Topological Design of Parallel Mechanisms
Authors: Yang Ting-Li , Liu An-Xin , Jin Qiong , Luo Yu-Feng , Shen Hui-Ping , Hang Lu-Bin
Published: July 2009

This paper presents the explicit mapping relations between topological structure of parallel mechanism and position and orientation characteristic (in short, POC) of its motion output link. It deals with: (1) The symbolic representation and the invariant of topological structure of mechanism; (2) The matrix representation of POC of motion output link; (3) The POC equations of parallel mechanism and its symbolic operation rules. The symbolic operation involves simple mathematic tools and fewer operation rules, and has clear geometrical meaning. So, it is easy to use. The forward operation of the POC equations can be used for structural analysis; its inverse operation can be used for structural synthesis. The method proposed in this paper is totally different from the methods based on screw theory and based on displacement subgroup.
Locating Precision of Fit Datums
Authors: Etesami Faryar
Published: July 2009

One of the methods design engineers use to achieve alignment between precision features of two mating parts is through locating or alignment features. The most common locating features are a pair of small holes and pins that would define the in-plane position and orientation of two parts with respect to each other. These locating features establish a datum frame for all other critical features of a part. Design engineers would be interested to know the worst-case and probabilistic value of misalignments resulting from their choices of tolerances that assure fit of the datum features as well as their choices of tolerances that locate the precision features with respect to such a datum. This paper uses two-dimensional tolerance analysis methods to formulate this alignment problem. Worst-case estimates as well as Monte Carlo simulation have been used to analyze the misalignments resulting from play in the datum fit. It is shown that a number of dimensionless parameters can characterize the misalignment and these are used to create graphs adequate for design work.
Active Learning, Collaborative, and Problem-Based Design Engineering Course Series at the American University of Beirut
Authors: Hamade Ramsey F. , Ghaddar Nesreen
Published: July 2009

In this paper, we present a student-centered, two-course series in mechanical design at junior level that emphasizes student self-learning of technical knowledge, communication, and problem solving in a setting full of creativity and innovation. The mechanical engineering student performance is tracked in upper level classical mechanical design courses MECH420 and MECH520 Mechanical Design I & II to correlate impact of team roles and performance on learning design skills. The first course in the series (ASST 200) is offered in Term I (the fall term of the first year) and emphasizes basic product development concepts. Set in a team environment, diverse topics such as reverse engineering and artifact dissection, sound engineering practices, ethics in engineering, and human relations are introduced. The second introductory course MECH 321 in the design series is project-centered and is offered in the fall term of the 2nd year. This course emphasizes design creativity in the context of product development. The students, in organized teams of four, tackle an open-ended engineering problem by having to design a custom micro car. The course climaxes in a 5-event contest during which these micro-cars are put to action in what is known around the campus as the Gee Whiz contest. A strong correlation was found between performance in these introductory courses and more advanced design courses. It is also found that the student role as project analyst or manager through inter-dynamics of his/her team significantly affects improved learning skills at higher level courses.
Design and Analysis of a New Six-DOF Parallel Haptic Device With Singularity-Free Task Workspace
Authors: Yang Yi , Zhang Yuru , Zhang Yaojun , Cao Yonggang
Published: July 2009

This paper presents a procedure to obtain a singularity-free task workspace with a new method to deal with singularities. In order to get an enlarged singularity-free task workspace, we first optimize the volume of the workspace, then we identify singularities in the optimal workspace, and finally we refine the singularity-free task workspace from the optimal workspace. The effects of four physical constraints on the workspace are analyzed, subject to which the optimization is realized. The traditional approach of singularity analysis is based on the Jacobian Matrix which is direct but has limitations, especially when the analytical form of the Jacobian is difficult to obtain. To solve this problem, we define a pseudo-singular space which encloses all singularity loci. By searching the pseudo-singular space numerically, we are able to obtain a singularity-free task workspace. We illustrate this method in the designing process of a 6-RSS parallel mechanism as a haptic device which has been integrated in a simulated dentist training system.
Fuzzy Controlled Hooke-Jeeves Optimization Search Algorithm
Authors: Somasundaram Deepak Sankar , Trabia Mohamed B.
Published: July 2009

This paper presents an approach to enhance Hooke-Jeeves optimization search algorithm using fuzzy logic. Hooke-Jeeves algorithm, similar to many other search algorithms, use predetermined fixed parameters. These parameters do not depend on the objective function values at the current search location. Fuzzy logic controllers are incorporated in at various stages of the algorithm to create a new optimization search algorithm: Fuzzy-Controlled Hooke-Jeeves algorithm. The results of this paper shows that incorporating fuzzy logic in Hooke-Jeeves algorithm can enhance the ability of the algorithm to reach extremum in different typical optimization test cases and design problems.
A New Concept for Requirements Driven Project Planning in an Integrated PLM Environment
Authors: Maletz Michael , Brisson Dan , Zeng Yong
Published: July 2009

Integration in today’s heterogeneous PLM environments is a key factor in all development phases. This paper describes a methodical approach to integrating requirements modeling into a PLM environment. The specific focus of integration aspects is on project planning of complex mechatronic products with recurrent character based on requirements specification documents. Function and process orientation serves as a basis for the integration. It is discussed how development projects teams can benefit by generating project plans including resource estimations and predefined interfaces to bordering disciplines along the development process. With the help of semantic parsing methods of natural language requirements and through a generic classification system a requirement based product and process model is generated. This model is then taken as the basis for deriving product and process related information. Through domain specific ontology’s generic project and resource plans are generated with the help of the proposed methodology.
3D Visualization-Based Training Systems for Product Maintenance
Authors: Peng Qingjin , Zhang Tong , Xie Yikun
Published: July 2009

Maintainability is an important criterion for product lifecycle management (PLM). Product maintenance needs experience and skills of the product structure and operations. It can significantly improve the understanding of a product and efficiency of product maintenance using user-friendly interfaces to show product details and operations. 3D visualization technology provides a useful tool for the understanding of product and maintenance training. Product structure and the operation process can be clearly shown and run in 3D visualized user interfaces. A framework is proposed for 3D visualization-based training systems in this paper for the aid of understanding in product maintenance. The needs and implementation of the framework are discussed. Two applications are developed to demonstrate the feasibility of the proposed method.