bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of Multiple Mobile Agents Via Artificial Potential Functions and Random Motion
Authors: Kumar Manish , Garg Devendra P. , Zachery Randy
Published: May 2009

This paper investigates the effectiveness of designed random behavior in cooperative formation control of multiple mobile agents. A method based on artificial potential functions provides a framework for decentralized control of their formation. However, it implies heavy communication costs. The communication requirement can be replaced by onboard sensors. The onboard sensors have limited range and provide only local information, and may result in the formation of isolated clusters. This paper proposes to introduce a component representing random motion in the artificial potential function formulation of the formation control problem. The introduction of the random behavior component results in a better chance of global cluster formation. The paper uses an agent model that includes both position and orientation, and formulates the dynamic equations to incorporate that model in artificial potential function approach. The effectiveness of the proposed method is verified via extensive simulations performed on a group of mobile agents and leaders.
Resonance and Sound Attenuation in Periodic Arrays of Spherical Microspheres Embedded in Viscoelastic Polymer
Authors: Zhao Honggang , Yang Yongmin , Li Yue , Wen Xisen
Published: May 2009

Practical design of composite materials suggests a need for an improved quantitative understanding of the interaction between acoustic waves and microspheres. In this work, we first investigate the Mie resonance of a single spherical microsphere embedded in polymer by referring to the elements of the scattering matrices. It shows that a hollow glass microsphere presents a similar monopole resonance as an air microsphere, but the resonance of a hollow glass microsphere occurs at a higher frequency with a wider bandwidth than that of an air microsphere. Then, using the multiple scattering method, we show that the low-frequency gap of a periodic array of microspheres in polymer is mainly induced by the monopole resonance of the single microsphere, and find a wide band gap under very low concentrations of the microspheres. The viscosity of the components induces the energy dissipation under the resonant scattering, and the attenuation of ultrasonic longitudinal waves in the polymer slab is dominated by energy absorption.
Design of Experiment Issues in Material Component Damage Detection Including Sensor Mass and Footprint Studies
Authors: White Jonathan R. , Adams Douglas E. , Sundararaman Shankar , Escobar Carlos
Published: May 2009

In structural health monitoring, the reliability of measured data for use in damage detection is greatly influenced by the sensor characteristics. Specific issues related to design of experiments in structural health monitoring are analyzed including sensor attachment, mass, frequency range, and footprint. A circular plate instrumented with various sensors and attachment methods (adhesive, stud) is used to study the effects of sensor bond on dynamic measurements. Attachment types are shown to have different amounts of measurement variability using an ANalysis Of VAriance technique. Differences in the amount of measurement variability lead to different damage detection thresholds. A validated sandwich metallic honeycomb panel finite element model is also used to conduct a numerical sensitivity analysis. Sensor mass is shown to reduce the sensitivity of damage detection for realistic sensor masses. The sensor footprint is shown to become an issue, by an acceleration field analysis, when the wavelength of the frequency of excitation is on the order of the sensor diameter.
A Hands-on Approach to Teaching Thermal Systems Design
Authors: Jokar Amir
Published: May 2009

Thermal Systems Design, as a senior undergraduate course, has been taught by several methods in different mechanical engineering curricula. The objective of this upper-level undergraduate course at WSU Vancouver is to enhance the student’s industrial vision, and to prepare them for mechanical engineering practice before they graduate. For this purpose, students first apply the concepts of thermodynamics, fluid mechanics, and heat transfer that they had previously learned in relevant fundamental courses, through the real world problems and design projects. To increase the ability of students in design and realization of thermal systems, a design competition is setup in class within the course timeframe. The present article reports the details and results of such a hands-on class activity.
Analysis of the Piezoelectric Ceramics PLZT With ANSYS
Authors: Liang L. , Wang S. P. , Cao F.
Published: May 2009

Traditional electric servo system is disturbed by electromagnetic interference, so optical servo system is needed to build urgently in order to avoid electric signal and electrical wire. Therefore, photostrictive ceramics becomes promising material to realize the optic-signal transmission and photostriction. Lanthanum-modified lead zirconate titanate (PLZT) ceramics, which also belongs to piezoelectric ceramics, is one of the most promising photostrictive materials that can stretch with the light intensity. Photostriction is the combination of the photovoltaic and converse piezoelectric effect. Because of little knowledge about photostriction, the piezoelectric characteristic of PLZT, which is a portion of the photostriction, is studied by use of coupled-field analysis of the Finite Element Analysis (FEA) software ANSYS. The detailed steps of modeling are given. The performances of unilateralism and multilayer PLZT are described, such as displacement output, stiffness and dynamics characteristics. It can be concluded that ANSYS calculation value is very close to the theoretical results by comparing those two results, so ANSYS software can be used to preestimate before we research the characteristics of piezoelectric devices.
Stability of Shear-Thinning Flow Between Rotating Cylinders
Authors: Ashrafi Nariman
Published: May 2009

The effect of shear thinning on the stability of the Taylor-Couette flow (TCF) is explored for a Carreau-Bird fluid in the narrow-gap limit to simulate shear-dependent viscosity of lubricants. Here, a low-order dynamical system is obtained from the conservation of mass and momentum equations. In comparison with the Newtonian system, the present equations include additional nonlinear coupling in the velocity components through the viscosity. It is found that the critical Taylor number, corresponding to the loss of stability of the base (Couette) flow becomes lower s the shear-thinning effect increases. Similar to Newtonian fluids, there is an exchange of stability between the Couette and Taylor vortex flows. However, unlike the Newtonian model, the Taylor vortex cellular structure loses its stability in turn as the Taylor number reaches a second critical value. At this point, A Hopf bifurcation emerges, which exists only for shear-thinning fluids.
The Development of Endodontic Micro Robot
Authors: Dong J. , Everett H.
Published: May 2009

Endodontic therapy, better known as root canal treatment, is a procedure performed to remove damaged and/or infected tissue from the inner canals of teeth and seal the canals to prevent the teeth from being a source of infection. Each year more than 24 million teeth receive endodontic treatment in the United States. A typical procedure includes access preparation (opening crown with drills), root canal shaping and cleaning, and then root canal filling. This treatment is expensive, time-consuming, and prone to human error. The outcome relies on the clinician’s skill, which is gained through years of training and practice. The success quotient of this treatment is 60–65% for general dentists and 90% for specialists (endodontists). There is a need for advanced endodontic technology innovation. This paper will describe the process of mechanical design of computer-controlled micro machine, which will perform the automatic probing, drilling, cleaning, and filling of the root canal. The paper will also discuss the innovations involved from the traditional way endodonticsts treat root canal to science and technology based automation.
Development and Control of “Stiff Drivers” for Thermoacoustic Refrigeration
Authors: DeJohn David W. , Vipperman Jeffrey S.
Published: May 2009

Thermoacoustic refrigerators offer advantages over vapor-compression refrigerators in terms of their inherent mechanical simplicity, lack of chlorofluorocarbon pollutants, and potentially low cost. However, current thermoacoustic refrigerator designs are inhibited by poor efficiency relative to their more conventional counterparts. This paper details attempts to improve the efficiency of a prototype standing-wave thermoacoustic refrigerator through the development of “stiff driver” actuators. Stiff drivers use electronically-driven, lightly-damped structural elements — such as plates or beams — as replacements for traditional drivers. The goal is to reduce the coupling of electromechanical dynamics and acoustical dynamics common to loudspeaker-driven designs while maintaining a cost lower than that of the highly-advanced linear actuators described in some literature. Hofler’s method of using phase-locked loop (PLL) control to track acoustic resonance is altered here in that the output from the PLL is used to modify the geometry of the driver, rather than its driving frequency [1]. Through proper control, the mechanical resonance frequency of the driver is matched to that of the acoustic resonator despite changes in temperature, working fluid, or other factors.
Stress Analysis and Strength of Scarf Adhesive Joints of Dissimilar Adherends Subjected to Static Bending Moments
Authors: Sawa Toshiyuki , Karami Atsushi
Published: May 2009

The stress distributions in scarf adhesive joints of dissimilar adherends under static bending moments are analyzed using three-dimensional finite-element calculations. The code employed is ANSYS. In FEM calculations, the effects of Young’s modulus of the adhesive, adhesive thickness, scarf angle of the adherend on the stress distributions at the adhesive interface are examined. As the results, it is found that the maximum value of the maximum principal stress occurs at the edge of the scarf adhesive interface. It is also observed that the maximum value of the stress is minimum, when the scarf angle is 60 degree. In addition, the joint strength is estimated using the obtained stress distribution. For the verification of the FEM calculations, the experiments were carried out to measure the strengths and the strains in the joints under static bending moments using strain gauges. Fairly good agreements are observed between the numerical and the measured results concerning the joint strength and the strains.
Post Healing Structural Response of an Internal Fixation System for a Mid-Shaft Radius Fracture
Authors: Coates Cameron , Coates-Clark Camille , Woody Mykal
Published: May 2009

Inexpensive models of the radius with and without an internal fixation system for a mid-shaft fracture are developed and analyzed using the Finite Element Method (FEM). FE models are based on geometry obtained from simple yet effective manufacturing methods. Median trabecular and cortical bone mechanical properties for a healthy adult male are used in the FEM model. These models are used to quantify the changes in bone stresses that occur when internal fixation devices are retained after the fracture has healed. The linear static responses to tensile and torsional loads with and without bone plates are examined. The static response trends obtained agree reasonably well with current literature where more expensive modeling techniques were used. A fatigue analysis is also performed based on the FE static results coupled with S-N curves for the plate and bone material in order to predict the combined mechanical response of the bone plate system over time. Recommendations are suggested which may be used as additional guidelines to consider for bone plate system selection and determination of hardware removal.
Stability Control of Haptic Interface
Authors: Zhang Jisheng , Li Jiting , Tomovic Mileta M. , Zhang Yuru
Published: May 2009

Haptic devices and man-machine interaction have attracted intense research interest in recent years due to numerous potential applications, including medical, dental, military, and nuclear. One of the challenges involved with haptic devices is providing human operator realistic sensory feeling through force feedback output from the haptic device. In order to acquire adequate fidelity, the stiffness of the virtual environment must be sufficiently large. However, this is typically accompanied with vibration of the haptic device. Hence, one of the key issues related to haptic systems is to ensure system’s stability. Although some effort has been done to address this issue, this is so far an unresolved problem. This paper presents current closed-loop PID control method for achieving system stability on the example of one-degree-of-freedom haptic device. In order to identify parameters of the PID controller, the control system is first modeled and the equation of the current closed-loop PID control is formulated. Then, by generalizing the relationship between the motor output torque and the virtual force at the output end of the device, the current closed-loop equation is transferred into that of the force. In addition, the paper analyzes the robustness of PID controlled haptic device. To validate the method, three simulation experiments are performed, with spring model, damper model, and spring damper model. The results show that there is a set of PID parameters which result in stable haptic device. One of the advantages of the proposed method is that it can regulate PID parameters to fit different virtual environment. This provides a fundamental approach to improve stability of haptic systems. In addition, the proposed method can be embedded in the software.
Characterization of Electronic Board Material Properties Under Impact Loading
Authors: Ayyaswamy Ashok Kumar , Sridharala Srujanbabu , Trabia Mohamed B. , O’Toole Brendan , Liu Qunli , Chowdhury Mostafiz
Published: May 2009

On-board electronics in advanced military apparatus are often subjected to severe ballistic shocks and vibrations. Safeguarding on-board electronic sensors from such transient shocks due to ballistic impact is of concern. While several studies document material characteristics of electronic boards under quasi-static and low impacts, few researchers addressed the behavior of these boards under severe impact loading. This paper presents the results of testing electronic boards under different strain rates to assess the effects of strain rates on modulus of elasticity of the boards. The results are used to suggest material models that can be used in finite element codes to accurately describe the behavior of these boards under impact loading.
Growth of Different Crystals Using a Modified Bridgman System
Authors: Wei Jiuan , Zheng Lili , Zhang Hui
Published: May 2009

This paper studies the favorable growth conditions for the III-V and II-VI crystals such as InAs, InSb, GaSe, GaP, PbTe and CdTe by the Bridgman technique. Numerical simulations have been conducted to investigate the flow field, temperature distribution in relation to the solidification interface shape and growth conditions for various materials. It is concluded that the growth is strongly affected by melt convection; a strong convection may destroy the interface stability, resulting in failed growth. The Grashof and Prandtl numbers are identified as the key parameters affecting the growth interface stability. Based on these two parameters, a growth process map is developed to quantify the difficulty of growth for different materials by Bridgman technique. To accommodate the growth of large diameter crystal, a new growth system based on Bridgman configuration is proposed in which two hot-zone furnace is introduced and the feasibility of using this system to suppress the melt convection, subsequently generating favorable growth conditions has been confirmed from the numerical simulations.
Preliminary Study of Pressure Drop and Heat Transfer Through a Friction Stir Channel
Authors: Balasubramanian Nagarajan , Krishnamurthy K. , Mishra Rajiv S.
Published: May 2009

Commercially available compact heat exchangers are currently fabricated in several steps by joining multiple tubes, or by independently fabricting and joining fluid channels. Friction stir channeling (FSC) is a simple and innovative technique of manufacturing heat exchangers in a single step in a monolithic workpiece. During friction stir welding (FSW), a defect referred to as ‘wormhole’, is created if the processing parameters (tool traverse speed, tool rotation speed, and tool plunge depth) are not correct. FSC is based on converting this defect formation during FSW into a manufacturing technique for heat exchanger applications. If used to produce a cooling system or heat exchanger, FSC can provide many benefits over standard industrial practices in terms of simplicity in manufacturing. Experiments have shown that a continuous hole in a single plate can be created by selecting the optimum process parameters. The channel is characterized by roughness features on the inside, which can be analyzed using optical microscopy techniques. In this paper, five such channels with different hydraulic diameters are tested for the pressure drop and heat transfer. The thermal behavior of a friction stirred channel is simulated using the commercial CFD code FLUENT. Pressure drop along the channel is studied for different surface roughness heights. Temperature difference of water between the inlet and the outlet of the channel is also measured for the channels.
Water Condensation and Two-Phase Flow Modeling for a Plate Heat Exchanger Channel
Authors: Wilhelmsson Charlotte , Yuan Jinliang , Sunden Bengt
Published: May 2009

There are water vapour condensation and two-phase flow in plate heat exchangers when they are used as condensers. Water phase change and flow dynamics modelling is an important but complicated task due to large change in water physical/transport properties across the water liquid-vapour interface boundary. In particular, singular-link behaviour in governing equations is present due to the large step change in the density when computational fluid dynamics (CFD) is employed. Conventional methods using ensemble averaged parameters such as void fraction are impossible to be applied to cases where high-resolution calculations and detailed analysis are required. In this study, a CFD approach is employed to model water vapour condensation and two-phase flow in a channel relevant for plate heat exchanger parallel plates. The developed model is based on the governing equations which are directly solved for the entire single- and two-phase fields. The water phase change and two-phase flow are treated by employing a water liquid-phase fraction factor based on the total enthalpy in each computational cell. The factor is defined as the ratio of the total enthalpy differential to the latent heat of condensation. The thermal-physical properties, such as density, viscosity and conductivity of the two-phase region, are calculated and updated based on the calculated value of the liquid-phase fraction factor until a converged result is reached. It is concluded that, among others, the inlet vapour velocity has significant effects on the water phase change and two-phase flow in the channel, in terms of liquid-water fraction factor distribution.
A Modified Q-Learning Algorithm for Multi-Robot Decision Making
Authors: Wang Ying , de Silva Clarence W.
Published: May 2009

This paper presents a modified distributed Q-learning algorithm termed the Sequential Q-learning algorithm with Kalman Filtering (SQKF), for multi-robot decision making. While Q-learning is employed commonly in the multi-robot domain to support robot operation in dynamic and unknown environments, it also faces many challenges. It is questionable to scale the conventional single-agent Q-learning algorithm into the multi-robot domain because such an extension violates the Markov assumption on which the algorithm is based on. The empirical results show that it can confuse the robots and render them unable to learn a good cooperative policy due to incorrect credit assignment among robots and also make a robot incapable of observing the actions of other robots in the same environment. In this paper, a modified Q-learning algorithm termed the Sequential Q-learning Algorithm with Kalman Filtering (SQKF), which is suitable for multi-robot decision-making, is developed. The basic characteristics of the SQKF algorithm are: (1) the learning process is not parallel but sequential, i.e. the robots will not make decisions simultaneously and instead, they will learn and make decisions according to a predefined sequence; (2) a robot will not update its Q values with observed global rewards and instead, it will employ a specific Kalman filter to extract its real local reward from the global reward thereby updating its Q-table with this local reward. The new SQKF algorithm is intended to solve two problems in multi-robot Q-learning: Credit assignment and Behavior conflicts. The detailed procedure of the SQKF algorithm is presented and its application is illustrated. Empirical results show that the algorithm has better performance than the conventional single-agent Q-learning algorithm or the Team Q-learning algorithm in the multi-robot domain.
Assess Team Q-Learning Algorithm in a Purely Cooperative Multi-Robot Task
Authors: Wang Ying , de Silva Clarence W.
Published: May 2009

Multi-robot systems have received more and more attentions in the robotics community in the past decade. The most important issue in this area is multi-robot coordination, which focuses on how to make multiple autonomous robots cooperate or compete with each other to complete a common task. Due to its complexity, the conventional planning-based or behavior-based approaches can not work well in multi-robot coordination, especially in a dynamic unknown environment. Therefore, machine learning is becoming a promising method to help robots work in an unknown dynamic environment and improve their performance increasingly. The Q-learning algorithm was selected by most of multi-robot researchers to accomplish the above objective because of its simplicity and low computational requirements. However, directly extending the single-agent Q-learning algorithm will violate its Markov assumption and result in a low convergence speed and failing to learn a good cooperative policy. In this paper, the team Q-learning algorithm, which was originally designed for the framework of Stochastic Games (SG), is proposed to make decisions for a multi-robot purely cooperative project: Multi-robot object transportation. Firstly, the basic idea of the framework of Stochastic Games and the team Q-learning algorithm are introduced. Next, the algorithm is extended to a multi-robot object transportation task, and the implementation details are presented. Some computer simulation results are presented to demonstrate that the team Q-learning algorithm works well to make decisions for the proposed multi-robot system. Finally, effects of some parameters of team Q-learning are assessed and some interesting conclusions are drawn. In particular, the simulation results show that training is helpful for improving the performance of multi-robot decision-making, but its effect is very limited. In addition, it is also pointed out that the team Q-learning will result in a huge learning space when the robot number is bigger than ten, which indicates that a new Q-learning algorithm integrating single-agent Q-learning and Team Q-learning is urgent to be developed for multi-robot systems.
Localization of Energy in a Perfectly Symmetric Bladed Disk Assembly Due to Nonlinearities
Authors: Georgiades F. , Peeters M. , Kerschen G. , Golinval J. C. , Ruzzene M.
Published: May 2009

Although a bladed disk is typically designed to have identical blades, manufacturing tolerances, wear, and other causes may cause random deviations among the blades. The blade-to-blade discrepancies, denoted as mistuning, lead to vibratory responses mostly concentrated in small regions of the bladed-disk assembly, according to a phenomenon called localization. The resulting spatial confinement of the vibration energy causes the responses of some blades to become dangerously high and increases the amplitude of the bladed-disk assembly’s overall response. The attendant increase in stresses can lead to premature high cycle fatigue (HCF) of the blades. In this study we investigate whether vibration localization in a perfectly symmetric bladed disk assembly may occur in the presence of nonlinearity. To this end, the nonlinear normal modes (NNMs) of a simplified model of a bladed disk assembly are computed. The NNMs are then carefully examined to highlight possible vibration localization phenomena.
Exploration of a Hybrid Locomotion Robot
Authors: Webb Jeffrey B. , Walter Wayne W.
Published: May 2009

Within the Kate Gleason College of Engineering (KGCOE) at the Rochester Institute of Technology (RIT), there has arisen a need for an efficient, variable-terrain robotic platform, with the ability to carry a payload with precision. This paper provides an overview of the work done toward the development of a hybrid locomotion robotic platform. The platform combines the benefits of both walking and rolling into a single integrated system. The robot will be shown to have the ability to traverse various terrain and obstacles.
A Study of Transient Thermal Spreading of VLSI Packaging With Multi Level Scaling
Authors: Yazawa Kazuaki , Yamashita Tenko , Kuroda Hideaki
Published: May 2009

Trend of VLSI chip power consumption sounds switch over from the Moore’s law to more moderate curve by the “multi core processing” paradigm. Many of the recent advanced VLSI chips adopt the multiple processing units since clock enhancement is no longer feasible to gain the expected performance based on realistic range of power consumption. Even though, heat flux may keep increasing by further fine semiconductor process and may keep localizing by further complex logics. In this study, thermal impact of hot spot size relative to chip size or the dimension of heat sink is investigated by analytic modeling as well as numerical analysis. The analytic transient thermal spreading model in a solid with transfer function has already proposed and was validated in our previous work. In this study, we have considered the impact of thermal interface between the heat source and conductive and spreading component to the sink. Thermal response in wide rage of scales is discussed from transistor level to a millimeter scale. Each level of such various sizes can be investigated individually and can be built up with some sort of cascade manner. Based on this model, thermal diffusion in silicon substrate, which has the thermal coupling with spreader and thermal interface, will be discussed for a further fine process generation of the chip. The result implies that passive thermal spreading can be achieving to the limit.
Using Dairy Cow Derived Biomethane to Fuel the Viking 32 Hybrid Electric Vehicle
Authors: Leonhardt Eric C. , Swazo Jamin F. , Cruse Ryan F.
Published: May 2009

A high performance vehicle—Viking 32—designed and built at the Vehicle Research Institute has been powered with methane refined from a dairy cow anaerobic digester. A student and faculty led team designed and constructed two different refining processes to investigate the feasibility of developing a renewable energy source for transportation in Whatcom County. The paper discusses several key issues surrounding anaerobic digester produced biomethane: the quantity and significance of the energy produced, why transportation fuel is a viable alternative to electrical production in anaerobic digester projects, and the environmental benefits of the anaerobic digester. The design, construction and test results of the two different refining techniques are reviewed as well. The systems are considered for application beyond dairy cow anaerobic digesters. Finally, a renewable transportation concept is proposed for biomethane based transportation in Whatcom County.
Motion Parameter Measurement of Mechanisms Using the Calculator Based Ranger System
Authors: Zhou Hong , Kunapareddi Bhargava , Pendyala Srinivas Rao
Published: May 2009

There is typically a project in the course of “Mechanism Design” or “Kinematics of Machines”. The purpose of the course project is to apply analysis and synthesis theories to practical mechanisms, strengthen the understanding of theories, improve analysis and synthesis skills of mechanisms, and prepare students to cope with practical engineering problems in industry. The real testing of mechanisms is often missing in the project because of the limited project time and the lacking of a simple and effective testing device. This paper introduces a simple, effective and efficient approach to measure the motion parameters of the analyzed or synthesized mechanisms for the course project. The Calculator Based Ranger (CBR™) System is used to measure motion parameters of mechanisms. The CBR™ system includes a sonic motion detector with a built-in microprocessor, a graphing calculator and some connecting cables. The CBR™ system sends out an ultrasonic pulse and then measures the time it takes for that pulse to return after bouncing off the closest object. When the data is collected, the CBR™ system calculates the distance of the object from the sonic motion detector using a speed-of-sound calculation, and then computes the first and second derivatives of the distance data with respect to time to obtain the velocity and acceleration data. Students first design and analyze the mechanisms. The mechanism performance is analyzed and the output link position, velocity and acceleration plots are generated by Matlab. Pro Engineer or AutoCAD is used for mechanism geometric modeling. The designed mechanisms are then fabricated in the department machine shop by the students. The output motion parameters of the fabricated mechanisms are measured by the CBR™ system. The measured output motion parameters are compared with the analysis results to improve the fabrication precision and measurement accuracy. In this paper, the scotch yoke mechanism is used to show the motion parameter measurement process. Students get hands on experience about the analysis, synthesis, fabrication, and testing of mechanical systems when the CBR™ system is incorporated with the course project.
Promoting Active Learning in Teaching the Course of Design of Machine Elements
Authors: Duan Shanzhong , Ries Andrew
Published: May 2009

For certain topics in the curriculum the pendulum of engineering education is swinging from a full focus on pure theory to a balance between theoretical analysis and solid experiences. Undergraduate students are required to obtain both theoretical knowledge and hands-on experiences to meet the need of job markets. Active learning/teaching has become a commonly-used instructional approach in response to this change of the balance. In the authors’ institute, the Design of Machine Elements (DOME) course has been used as a candidate for exploration on how to engage students in active learning in regular classroom settings through designed activities such as in-class-teams, think-pair-share, in-class-writing-assignments, problem-based learning, etc. If students are expected to perform well with open-ended and project-centered problems for their design courses and capstone senior design, then a pedagogical basis should be provided across the entire undergraduate design curriculum. This paper discusses how active learning/teaching techniques have been explored in teaching the course of Design of Machine Elements to build up such a basis. In this paper, active learning concepts applied in teaching the DOME course are discussed, including specific examples of integrating active learning techniques with traditional classroom lectures. Also presented are which active learning techniques have worked effectively, what experiences have been learned, and what issues need further improvements and exploration. In addition, the paper also discusses how course projects are assigned to line up with planned teaching and learning activities, and how project requirements have been designed to facilitate the integration of active learning techniques with instructional objectives. Anonymous student survey data and course assessments will be presented to show that these techniques indeed provide a promising solution to the integration of active learning/teaching methods into teaching the course of design of machine elements in the regular classroom setting.
Modeling and Analysis of Directional Control Valves With Tapered-Angle and Eccentric Clearance
Authors: Duan Shanzhong , Nielsen Tyler
Published: May 2009

Equations of motion of spool valves have been set up under ideal conditions without considering some important factors that may have a significant influence on dynamical behavior and performances of spool valves especially when valve sizes are small. In this paper, these factors are brought into considerations. One of them is the eccentric clearance existing between the spool and the sleeve of a valve due to fabrication errors. Another is the viscosity of a Newtonian fluid assumed to flow through the valve orifices, which generally results in shear forces acting on the valve spool. This paper discusses how equations of motion of spool valves are derived and solved with considerations of these factors. Concepts of Poiseuille flow and Couette flow are utilized to obtain axial forces acting on the valve spool. The resulting equations of motion of spool valves have the simple form of a second order linear ordinary differential equation under the imposed idealizations. The influences of these factors on the motion behavior of spool valves are in turn discussed.
The Effect of Cold Expansion at Chamfered Fastener Holes
Authors: Jang Jae-Soon , Kim Dae-Wook , Cho Myoung-Rae
Published: May 2009

Cold expansion method has been widely used to enhance fatigue properties of the aerospace structures with fastener holes. Basically, cold expansion method is that an oversized tapered mandrel goes through the hole and produces compressive residual stress as well as plastic deformation around the hole. One of the problems with the cold hole expansion process is lower compressive residual stress values of the entry hole position than those at other positions of the hole. Often, fatigue cracks are initiated at the entry position of the hole. In this study, applying chamfers on a hole is proposed to increase the residual stresses at the entry position. Finite element analysis (FEA) was conducted to predict residual stress distributions of cold hole expansion processed chamfered holes. FEA results show that the chamfered holes have equal distribution of deep compressive residual stresses around the hole while the holes without chamfers have lower compressive residual stresses at the entry hole position. Effects of chamfer geometries on residual stress distributions are also discussed.
Nonlinear State Estimation Using Aggregate Modeling
Authors: Kiriakidis Kiriakos , Feemster Matthew , O’Brien Richard T.
Published: May 2009

The paper addresses the state estimation problem for a general class of nonlinear systems. Using an expansion of nonlinear drift dynamics in terms of an aggregate model, the authors analyze the stability of the estimation error equation. Although the treatment is limited to linear feedback, the method results in quadratically stable error dynamics inside a large subset of the state space. The authors tested and verified the proposed approach on the nonlinear dynamics of the rotary pendulum.
Trajectory Generation for the Leg of the Six-Legged Underwater Robot Over Obstacle in the Structured Terrain
Authors: Wang Feng , Gu Linyi , Zhou Bo , Chen Ying
Published: May 2009

As safe and effective underwater vehicle, underwater robot is considered to be an ideal tool for the investigation and exploitation in the large offshore area. There has been a growing interest to develop six-legged underwater walking robot for the researchers since the six-legged locomotion is more flexible and adaptable on the seafloor than other types of locomotion. The trajectory for the leg of the six-legged walking robot has a great influence on the locomotion quality and efficiency when the robot is a heavy one. The power consumed in the locomotion with different leg trajectories differs from each other greatly. Therefore, it is of great significance to study the trajectory of the leg. Of all the locomotion of the walking robot, crossing over obstacle is a typical one. Thus this paper mainly studies the trajectory generation for the leg of the six-legged walking robot over obstacle in the structured terrain. The robot has eighteen DOF and all the joints are hydraulically driven. In the current study, technical analysis is performed with the emphasis on the power consumption while crossing over obstacle. The analysis is conducted at various trajectories so as to compare the power consumed in different trajectories. Meanwhile, the study has also taken the smooth movement of the joint into consideration. The trajectory of the leg is theoretically analyzed and simulated. The kinematic simulation and the power consumed with different trajectories are both conducted in MATLAB. Simulation results have demonstrated the influence of trajectory on the power consumption of the robot while crossing over obstacle. The study has provided a theoretical way for the trajectory generation over obstacle for the six-legged walking robot.
The Alula and Its Aerodynamic Effect on Avian Flight
Authors: Austin Bridget , Anderson Ann M.
Published: May 2009

The alula, a small thumb-like appendage on a bird wing, is often credited with increasing lift and decreasing the risk of stall during bird flight. Using field based studies; researchers have observed that the alula lifts away from the wing at critical moments in flight, such as take-off and landing. However, to date, there has been no conclusive experimental evidence to support the idea that use of the alula affects lift. To determine the effect of the alula on avian flight, we used a wind tunnel to study the wings of four ducks: the Wood Duck (Aix sponsa), the Redhead Duck (Aythya americana), the Black Scoter (Melanitta americana), and the Lesser Scaup (Aythya affinis). We used a combination of lift/drag measurements and Particle Image Velocimetry (PIV) to test the wings at velocities from 10–16 m/s and angles of attack from −20 to 25 degrees. The alula was observed to naturally lift as the stall angle was approached. Of the four wings, the Black Scoter demonstrated the largest maximum lift coefficient (1.4), followed by the Wood Duck (1.3), the Lesser Scaup (1.2) and lastly, the Redhead Duck (0.9). All four wings had minimum drag coefficients near 0.1. The Lesser Scaup was the only wing which had a measurable change in lift (10%) attributable to alula deployment. PIV results for the flow field around the Lesser Scaup wing showed higher velocities on the top side of the wing when the alula was deflected.
Experimental Study of the Flow Structure in Fire-Induced Whirlwinds Downwind of a Fire Using Particle Image Velocimetry
Authors: Shinohara Masahiko , Matsushima Sanae
Published: May 2009

The flow structure of fire-induced whirlwinds that occur downwind of a 90-cm-diameter methanol flame was investigated using particle image velocimetry (PIV) and a flow visualization technique. The PIV images showed that the whirlwinds occurred as counter-rotating vortices on both sides of a reverse flow downwind of the flame that moved toward it near the floor. The whirlwinds started near the floor and extended upwards, with a lower tangential velocity near the floor. The radius of the forced vortex region in the whirlwinds increased above a height of 11 cm. Whirlwinds downwind of the 90-cm-diameter methanol flame behaved the same as whirlwinds downwind of a 3-cm-diameter flame that were investigated in a previous study.
Impedance Shaping for Improved Feel in Hydraulic Systems
Authors: Kontz M. E. , Herrera M. C. , Huggins J. D. , Book W. J.
Published: May 2009

Applying haptic control to mobile hydraulic equipment presents a practical yet challenging application. One criticism of newer electro-hydraulic system is a lack of “feel.” To a haptics researcher this sounds like a call for haptic feedback in the human-machine interface. However, for an operator the “feel” of the system likely has more to do with how the actual system responds to forces or higher work port pressures. At some point, the high pressures slow down the system or naturally redirect flow to lower pressure circuits in a hydro-mechanical system. How this is done plays a large part in the “feel” of the system. In this paper, a paradigm is presented that tries to merge these two concepts of “feel.” Instead of trying to make the system transparent, the goal is to make the system react to forces acting on the system then use haptic feedback to help alert the operator to these forces. This is done by shaping this impedance so that the system provides a response or “feel” that is closer to a typical excavator. A haptic interface is used to enhance the haptic feel. Performance is evaluated using data from human-in-the-loop testing.
Delamination Evaluation Approach for Bimaterial Structure Considering Interfacial Layer
Authors: Yu Qiang , Shibutani Tadahiro , Shiratori Masaki , Matsuzaki Tomio , Matsumoto Tsubasa
Published: May 2009

In recent years, interfacial fracture is one of the most important issues in the assessment of reliability of electronics packaging. In particular, underfill (UF) resin is used to prevent thermal fatigue of solder joints in flip chip packaging. Interfacial fracture between components/substrates and UF resin also affects the reliability of electronic devices. In general, the interfacial strength can be evaluated with the concept of interfacial fracture mechanics. However, as new materials and new processes using in the devices increase, it becomes clear that the fracture concept is difficult to evaluate the interfacial strength quantitatively. Many researches assumed that the interface is bonded perfectly. However, the interface has the micro-scale structure and the bonding may be imperfect. Specially interfaces of the resin have complicated structure. In this study, an alternative approach for evaluating the mechanical fracture of the interfacial structure of resin in electronic components was proposed. The basic mechanical behavior of the new interfacial model with imperfect bonding layer was examined by using finite element analysis. The stress field around the interfacial layer depends not only on the properties of interfacial layer but also on the micro structure of the interfacial layer. In addition, based on the experimental result of the tensile and the shearing test from the reference, the mechanical models of the interfacial structure were constructed. The conditions of delamination were examined by using FEA Furthermore, the new model and approach was confirmed quantitatively. It was found that the basic properties of the interfacial layer can be tuned to the proper values by two different delamination tests, and the new approach could show good agreement with the experimental results from the initial delaminaiton to the instability fracture process qualitatively. The simulation results were in good agreement with the experimental results.
Functional and Behavioral Representation of Product Information for Collaboration in Product Lifecycle
Authors: Baysal Mehmet Murat , Sarigecili Mehmet I. , Roy Utpal
Published: May 2009

In this study, a functional and behavioral representation model for collaboration in product development is developed to represent assembly-related product knowledge, including its geometry, spatial relationships, function and behavior, which will be used to create a knowledge representation scheme to capture, store, and retrieve product knowledge. In this model, the function, behavior and artifact information is interrelated based on assembly associations. Functional and behavioral inputs and outputs are defined based on the spatial relationships in the assembly, as well as on the geometry of the product. The functional associations among artifacts define the “Behavior Model” with engineering formulas and physical rules. “Behavior Models” then define the behavior of the artifact. Behavior has four different forms for different phases in life cycle: (1) Intended Behavior in the conceptual design phase, (2) Estimated Behavior in the design phase, (3) Observed Behavior in the operation stage, and (4) Evaluated Behavior in the design and operation phases. When an unintended event (behavior) occurs, an additional function can be added to eliminate that effect. As a result, the functional and behavioral model is updated dynamically.
Numerical Study of Droplet Behavior in Straight and L-Shaped Channels
Authors: Kang Chang-Wei , Hua Jinsong , Lou Jing
Published: May 2009

Numerical simulations using three-dimensional front tracking method are conducted to study the effects of droplet properties on the transient motion, rotation and deformation of a droplet during its transit in straight and L-shaped rectangular channels. The properties under investigation for straight channel are the density ratio, viscosity ratio, Reynolds number, Weber number and droplet initial position. The latter two parameters are chosen for the study of L-shaped channel. The results show that in the straight channel, despite the droplet initial positions, the droplet with the same properties ends up at the same equilibrium position. However, when the Reynolds number increases, the droplet is heavier or less viscous or droplet becomes more deformable, the droplet equilibrium position is much closer to the wall. Also, heavier or less viscous droplet exhibits higher rotational speed, which is believed to enhance oscillatory motion. As for the L-shaped channel, it is found that the droplet deformability can help to avoid the droplet from impacting upon the channel wall.
Multi-Pulse Heteroclinic Orbits With a Melnikov Method and Chaotic Dynamics in Motion of Parametrically Excited Viscoelastic Moving Belt
Authors: Yao Ming-Hui , Zhang Wei , Cao Dong-Xing
Published: May 2009

The multi-pulse heteroclinic orbits and chaotic dynamics of a parametrically excited viscoelastic moving belt are studied in detail. Using Kelvin-type viscoelastic constitutive law, the equation of motion for viscoelastic moving belt with the external damping and parametric excitation are determined. The four-dimensional averaged equation under the case of 1:1 internal resonance and primary parametric resonance is obtained by directly using the method of multiple scales and Galerkin’s approach to the partial differential governing equation of motion for viscoelastic moving belt. The system is transformed to the averaged equation. From the averaged equation, the theory of normal form is used to find the explicit formulas of normal form. Based on normal form obtained, an extension of the Melnikov method is utilized to analyze the multi-pulse global bifurcations and chaotic dynamics for a parametrically excited viscoelastic moving belt. The analysis of global dynamics indicates that there exist the multi-pulse jumping orbits in the perturbed phase space of the averaged equation. From the averaged equations obtained, the chaotic motions and the Shilnikov type multi-pulse heteroclinic orbits of viscoelastic moving belts are found by using numerical simulation. The results obtained above mean the existence of the chaos for the Smale horseshoe sense for a parametrically excited viscoelastic moving belt.