bluuebunny/crossref_metadata_2025 huggingface dataset:
Loaded Tooth Contact Analysis and Stresses in Spiral Bevel Gears
Authors: Simon Vilmos V.
Published: July 2010

The method for loaded tooth contact analysis is applied for the investigation of the influence of misalignments and tooth errors on load distribution, stresses and transmission errors in mismatched spiral bevel gears. By using the corresponding computer program the influence of pinion’s offset and axial adjustment error, angular position error of the pinion axis and tooth spacing error on tooth contact pressure, tooth root stresses and angular displacement of the driven gear member from the theoretically exact position based on the ratio of the numbers of teeth is investigated. The obtained results have shown that in general, the misalignments in spiral bevel gears worsen the conjugation of contacting tooth surfaces and in extreme cases cause edge contact with high tooth contact pressures. But, some mismatches, as are the axial movement of the pinion apex towards the gear teeth or the tip relief of pinion teeth (in this analysis it is represented by the tooth spacing error) reduce the maximum tooth contact pressure. Also it can be concluded that the misalignments and the tooth spacing errors significantly increase the angular position error of the driven gear from the theoretically exact position based on the numbers of teeth and make the motion graphs unbalanced.
A Filter-Based Sample Average SQP for Optimization Problems With Highly Nonlinear Probabilistic Constraints
Authors: Hsu Kai-Hsun , Chan Kuei-Yuan
Published: July 2010

In this work we extend a filter-based sequential quadratic programming (SQP) algorithm to solve reliability-based design optimization (RBDO) problems with highly nonlinear constraints. This filter-based SQP uses the approach of average importance sampling (AAIS) in calculating the values and the gradients of probabilistic constraints. AAIS allocates samples at the limit state boundaries such that relatively few samples are required in calculating constraint probability values to achieve high accuracy and low variance. The accuracy of probabilistic constraint gradients using AAIS is improved by a sample filter to eliminate sample outliers that have low probability of occurrence and high gradient values. To ensure convergence, this algorithm replaces the penalty function by an iteration filter to avoid the ill-conditioning problems of the penalty parameters in the acceptance of a design update. A sample-reuse mechanism is introduced to improve the efficiency of the algorithm by avoiding redundant samples. ‘Unsampled’ region, the region that is not covered by previous samples, is identified by the iteration step lengths, the trust region, and constraint reliability levels. As a result, this filter-based sampling SQP can efficiently handle highly nonlinear probabilistic constraints with multiple most probable points or functions without analytical forms. Several examples are demonstrated and compared with FORM/SORM and Monte Carlo simulation. Results show that by integrating the modified AAIS with the filter-based SQP, overall computation cost can be significantly improved in solving RBDO problems.
Trajectory Planning and Coordinated Control of Robotic Systems
Authors: Soltan Reza A. , Ashrafiuon Hashem , Muske Kenneth R.
Published: July 2010

A new method combining trajectory planning and coordination or formation control of robotic and autonomous systems is presented. The method generates target trajectories that are either asymptotically stable or result in a stable limit cycle. The former case is used to implement formation control. Coordination is guaranteed in the latter case due to the nature of limit cycles where non-crossing independent paths are automatically generated from different starting positions that smoothly converge to closed orbits. The use of position feedback in the trajectory generation allows for simultaneous determination of a stable tracking control law and consideration of constraints and system limitations. The tracking control law presented in this work is based on sliding mode control which is suitable for real-time implementation. It is also robust to modeling uncertainties and disturbances normally encountered in autonomous operations. A system of robotic manipulators and a group of autonomous vehicles are used as examples to demonstrate the capabilities and advantages of the proposed method.
Metrics-Based Approach for VR Technology Evaluation in Styling Product Design
Authors: Germani Michele , Mengoni Maura , Peruzzini Margherita
Published: July 2010

In recent years, the interest of small and medium sized enterprises towards Virtual Reality (VR) systems is strongly increased thanks both to the improvement of VR tools effectiveness and to the cost reduction of technologies implementation. Due to the growing number of installed systems, many SMEs (Small Manufacturing Enterprises) companies require robust methods for evaluating technology performance. In this context, the present paper presents a metrics-based approach in order to analyze the VR system performance. It is specifically dedicated to the design review process during styling product design. The evaluation parameters are related to the effective communication and preservation of design intent. Metrics are classified in two main classes. The first one is related to the product, the process and the characteristics of VR technology. The second one is related to the design intent meanings preservation along the design process. Two experimental case studies are reported in order to test the approach in different operative fields.
Measurement Over Balls of Conical Involute Gears
Authors: Innocenti Carlo
Published: July 2010

The paper reformulates the theory of the measurement over spheres of conical involute gears by simplifying its algebra and extending it to internal gears. Moreover, a five-measurement technique is proposed that retrieves information about all basic parameters of a conical involute gear. Numerical examples show application of the reported results to case studies.
Computerized Design of Gear Drives With Modified Elliptical Centrodes
Authors: Fuentes Alfonso , Gonzalez-Perez Ignacio , Litvin Faydor L. , Hayasaka Kenichi
Published: July 2010

Gear drives with modified elliptical centrodes allows obtaining an asymmetric derivative function of the gear ratio. In this paper, the geometrical aspects of modification of elliptical centrodes as well as their analytical determination have been considered. A general equation for the center distance of modified elliptical gears that can be applied for conventional elliptical gear, oval gears, and gears with lobes has been derived. The results of application of modified elliptical gears to drive the crank member of a crank-slider linkage with the purpose of modification of the working and free-running cycles of a conventional crank-slider mechanism are presented. Two examples of tandem design of modified elliptical gears coupled with a crank-slider linkage have been considered.
Computerized Design of Muti-Gear Drives for Function Generation
Authors: Gonzalez-Perez Ignacio , Fuentes Alfonso , Litvin Faydor L. , Hayasaka Kenichi
Published: July 2010

A new approach for generation of functions based on application of a multi-gear drive is proposed. The approach provides solution to the functional Ψ(α) = gn(gn−1(⋯(g1(α)))) wherein Ψ(α) is the function assigned for generation and gi(α), i = 1,⋯,n, is the transmission function of pair i of conjugated non-circular gears. The specifics characteristics of the proposed approach are: (a) integrated impact by application of n synchronized gear drives, (b) favourable shape of centrodes, and (c) observation of limits of pressure angle. The developed theory is illustrated with several detailed numerical examples.
Optimal Design of a 3-DOF Parallel Micromanipulator
Authors: Zhang Dan , Gao Zhen , Li Beizhi
Published: July 2010

A new compliant parallel micromanipulator is proposed in this paper. The manipulator has three degrees of freedom (DOF) and can generate motions in a microscopic scale. It can be used for biomedical engineering and fiber optics industry. In the paper, the detailed design of the structure is first introduced, followed by the kinematic analysis and performance evaluation. Second, a finite-element analysis of resultant stress, strain, and deformations is evaluated based upon different inputs of the three piezoelectric actuators. Finally, the genetic algorithms and radial basis function networks are implemented to search for the optimal architecture and behavior parameters in terms of global stiffness, dexterity and manipulability.
Singularity Analysis of 5-RPRRR Parallel Mechanisms via Grassmann Line Geometry
Authors: Tale Masouleh Mehdi , Gosselin Cle´ment
Published: July 2010

This paper investigates the singular configurations of five-degree-of-freedom parallel mechanisms generating the 3T2R motion and comprising five identical legs of the RPUR type. The general mechanism was recently revealed by performing the type synthesis for symmetrical 5-DOF parallel mechanisms. In this study, some simplified designs are proposed for which the singular configurations can be predicted by means of the so-called Grassmann line geometry. This technique can be regarded as a powerful tool for analyzing the degeneration of the Plu¨cker screw set. The main focus of this contribution is to predict the actuation singularity, for a general and simplified design, without expanding the determinant of the inverse Jacobian matrix (actuated constraints system) which is highly nonlinear and difficult to analyze.
Calculation of Isothermal Intrinsic Compressibility and Compression of GvpA Protein in Halobacterium sp. NRC-1 Using Molecular Modeling and Dynamics
Authors: EzzEldin Hussein M. , Solares Santiago D.
Published: July 2010

Gas vesicles are low-density, gas-filled protein organelles found inside various microorganisms. They have a lipid-free membrane with an average thickness of 2 nm and provide their hosts with buoyancy. In this study we characterized gas vesicle proteins synthesized by the Halobacterium sp. NRC-1 strain making use of molecular modeling methods and molecular dynamics (MD) simulations. The tertiary structure of GvpA protein, the major constituent of the gas vesicle membrane, was predicted using the De Novo computational design method available in the Rosetta Suite 2.3.1 software and was found to be in agreement with experimental data available from previous studies conducted by others and the consensus of different secondary structure prediction web servers. Optimization of the predicted structure was first carried out by energy minimization and simulated annealing. Subsequently, the mechanical properties of GvpA were investigated via constant pressure and temperature (NPT) aqueous MD simulations, in which two approaches were used to study the isothermal compressibility: quantification of the fluctuations in protein volume at constant pressure and temperature, and quantification of the volume changes induced through changes in the simulation pressure. Long term we plan to incorporate this information into multi-scale models of whole gas vesicles.
Performance Comparison of Metamodeling Methods From the Perspective of Sample Quality Merits
Authors: Zhao Dong , Xue Deyi
Published: July 2010

Although many metamodeling methods have been developed in the past decades to model the relationships between input and output parameters, selection of an appropriate or the optimal metamodel for solving a certain engineering problem is not a trivial task. Various performance measures of different metamodels are strongly influenced by the characteristics of sample data. This research focuses on the study of the relationships between sample data characteristics and metamodel performance measures considering different types of metamodeling methods. In this research, sample quality merits are introduced to quantitatively model the characteristics of sample data. In this work, four types of metamodeling methods, including multivariate polynomial model, radial basis function model, kriging model and Bayesian neural network model, three sample quality merits, including sample size, uniformity and noise, and four performance evaluation measures, including accuracy, confidence, robustness and efficiency, are considered to study the relationships between the sample quality merits and the performance measures of the metamodeling methods.
Modeling of Geometric Variations Within a Tolerance-Zone for Circular Runout
Authors: Clasen Patrick J. , Davidson Joseph K. , Shah Jami J.
Published: July 2010

The geometric variations in a tolerance-zone can be modeled with hypothetical point-spaces called Tolerance-Maps (T-Maps) for purposes of automating the assignment of tolerances during design. The objective of this paper is to extend this model to represent tolerances on circular runout which limit geometric manufacturing variations to a specified tolerance-zone. Such a zone is an annular area at one transverse cross-section for spherical, conical, or cylindrical objects (features), but it is a short cylinder when the feature is a round or annular segment of a plane. Depending on the kind of feature and the tolerances that are specified for it, the model may be used to represent variations within tolerance-zones for circular runout, size, position, orientation, and form. In this paper, the Tolerance-Map (T-Map) is a hypothetical volume of points that captures all the circular variations that can arise from these tolerances. The model is compatible with the ASME/ANSI/ISO Standards for geometric tolerances. T-Maps have been generated for other classes of geometric tolerances in which the variation of the feature are represented with a plane or line, and these have been incorporated into testbed software for aiding designers when assigning tolerances for assemblies. In this paper the T-Map for circular runout is created and, for the first time, circles are used to represent the geometric variations of a feature in tolerance-zones.
Topology Optimization of Non-Linear Elastic Structures by Using SLP
Authors: Stro¨mberg Niclas
Published: July 2010

In this paper a method for topology optimization of nonlinear elastic structures is suggested. The method is developed by starting from a total Lagrangian formulation of the system. The internal force is defined by coupling the second Piola-Kirchhoff stress to the Green-Lagrange strain via the Kirchhoff-St. Venant law. The state of equilibrium is obtained by first deriving the consistency stiffness matrix and then using Newton’s method to solve the non-linear equations. The design parametrization of the internal force is obtained by adopting the SIMP approach. The minimization of compliance for a limited value of volume is considered. The optimization problem is solved by SLP. This is done by using a nested approach where the equilibrium equation is linearized and the sensitivity of the cost function is calculated by the adjoint method. In order to avoid mesh-dependency the sensitivities are filtered by Sigmund’s filter. The final LP-problem is solved by an interior point method that is available in Matlab. The implementation is done for a general design domain in 2D by using fully integrated isoparametric elements. The implementation seems to be very efficient and robust.
On the Design of a Self-Balanced Quadruped Walking Machine With Ten-Bar Leg Mechanisms
Authors: Yan Hong-Sen , Huang Chih-Yung
Published: July 2010

A self-balanced quadruped walking machine with leg mechanisms of 10-bar linkage is designed by a systematic approach. At first, an existing leg mechanism of 10-bar linkage is selected as the tentative design, and the dimensional synthesis is performed to obtain the desired foot trajectory by the optimization technique of ALM. Next, the speed ratio between the crank speed during the support phase and that during the transfer phase is decided by a two-speed control method to achieve a sufficient time period of support phase. Then, in order to make sure that there are always at least three legs on the ground for the wave gait to enhance the stability of locomotion, the foot point of each leg at a specific time is placed on the specific position upon the foot trajectory. The force analysis and computer simulation are carried out to evaluate the requirements for driving and to recognize the characteristics of the designed walking machine. And, the force transmission during the full cycle is realized and the specification of the driving motor is decided. Finally, a prototype of the designed quadruped walking machine is constructed and it is proven that this design is practical and feasible.
Correlation Improvement Between Theoretical and Experimental Results of PZT Thin-Film Membrane Actuators
Authors: Lee Cheng-Chun , Cao G. Z. , Shen I. Y.
Published: July 2010

This paper is to study actuation displacement of a Lead Zirconate Titanate (PbZrxTi1−xO3 or PZT) thin-film membrane actuator via finite element modeling and laser-Doppler measurements. In particular, this paper is to identify possible parameters that could cause discrepancies between the finite element predictions and experimental measurements. A twofold approach is used. First, we conduct additional experiments to measure actuator dimensions, which are subsequently used as input to the finite element model. We also measure natural frequencies of the membrane actuators to compare with the finite element predictions in addition to the actuator displacement. Second, we have conducted a parametric study via the finite element model to identify possible parameters that could cause the discrepancies. Parameters varied include dimensions, material properties, residual stresses and linearity of the PZT thin-film membrane actuator. Simulation results indicate that the residual stresses are the most probable cause of the discrepancy between the theoretical predictions and the experimental results.
Strain-Based Topology Optimization for Crashworthiness Using Hybrid Cellular Automata
Authors: Guo Lianshui , Penninger Charles L. , Renaud John E. , Tovar Andre´s
Published: July 2010

Structural design for crashworthiness is a challenging area of research due to large plastic deformations and complex interactions among diverse components of the vehicle. Previous research in this field primarily focused on energy absorbing structures that utilize a desired amount of material. These structures have been shown to absorb a large amount of the kinetic energy generated during the crash event; however, the large plastic strains experienced can lead to failure. This research introduces a new strain-based topology optimization algorithm for crash-worthy structures undergoing large deformations. This technique makes use of the hybrid cellular automaton framework combining transient, non-linear finite-element analysis and local control rules acting on cells. The set of all cells defines the design domain. In the proposed algorithm, the design domain is dynamically divided into two sub-domains for different objectives, i.e., high strain sub-domain (HSSD) and low strain sub-domain (LSSD). The distribution of these sub-domains is determined by a plastic strain limit value. During the design process, the material is distributed within the LSSD following a fully-internal-energy-distribution principle. To accomplish that, each cell in the LSSD is driven to a prescribed target or set point value by modifying its stiffness. In the HSSD, the material is distributed to satisfy a failure criterion given by a maximum strain value. Results show that the new formulation and algorithm are suitable for practical applications. The case studies demonstrate the potential significance of the new capability developed for a wide range of engineering design problems.
Rack and Pinion Steering Linkage Synthesis Using an Adapted Freudenstein Approach
Authors: Leishman Robert C. , Chase Kenneth W.
Published: July 2010

Rack and pinion steering systems have been synthesized and designed for many automotive applications. A steering system must be optimized for best steering characteristics to reduce tire wear and to assure safety and stability. Unfortunately, each design is slightly different because of differing car parameters and different space constraints. Designers need a tool that can quickly provide optimally synthesized steering systems. A precise and efficient method has been developed to assist designers in finding an optimum planar mechanism design for rack and pinion steering systems. It can be used to design central take-off or side take-off steering systems that are in a leading or trailing configuration. This method combines a modified Freudenstein equation with numerical optimization. Because of the combination of methods, an optimized solution may be found quickly. Thus, the tool is well adapted for preliminary designs and for design iteration.
Molecular Dynamics Study of Success Evaluation for Metallic Nanoparticles Manipulation on Gold Substrate
Authors: Mahboobi Seyed Hanif , Meghdari Ali , Jalili Nader
Published: July 2010

Using molecular dynamics, the behavior of nanoparticles during manipulation process is investigated in this paper. The system consists of a tip, cluster and substrate. The focus of the present research is on ultra-fine metallic nanoclusters. The system of concern is made of different transition metals. Two criteria have been proposed for evaluation of success in a pushing process. Such criteria describe the intactness of nanoparticle/substrate pair. The effects of cluster material and manipulation speed on the success of the process are investigated by atomistic simulations. Such qualitative simulation studies can evaluate the level of success of manipulation regarding different working conditions before consuming high experimental expenses.
Comparison Between a Polynomial-Chaos-Based Bayesian Approach and a Polynomial-Chaos-Based EKF Approach for Parameter Estimation With Application to Vehicle Dynamics
Authors: Blanchard Emmanuel , Sandu Corina , Sandu Adrian
Published: July 2010

Many parameters in mechanical systems cannot be measured physically with good accuracy, which results in parametric and external excitation uncertainties. This paper compares two new computational approaches for parameter estimation. The first approach is a polynomial-chaos based Bayesian approach in which maximum likelihood estimates are obtained by minimizing a cost function derived from the Bayesian theorem. The second one uses an Extended Kalman Filter (EKF) to obtain the polynomial chaos representation of the uncertain states and the uncertain parameters. The two methods are illustrated on a nonlinear four degree of freedom roll plane vehicle model, where an uncertain mass with an uncertain location is added on the roll bar. Both approaches can work with noisy measurements and yield results close to the actual values of the parameters, except when different combinations of uncertain parameters lead to essentially the same time response than the measured response. In that case, the aposteriori probability densities of the estimated parameters obtained with the EKF approach cannot be trusted. The Bayesian approach identifies that problem since the Bayesian cost function has an entire region of minima, and can use regularization techniques to yield most likely values in that region based on apriori knowledge.
Development of a Hybrid Involute Gear Profile
Authors: Haupt B. Levi , Jones Isaac R. , Todd Robert H.
Published: July 2010

To achieve a gearset which will maintain the beneficial properties of using involute shaped teeth, while allowing the gear ratio to vary, a new gear profile has been identified. This new gear profile termed the “Hybrid Involute Profile”, maintains the unique characteristics of an involute gear profile with the addition of a specified angular acceleration. This allows for one gear to be engaged with another gear while the ratio between the two gears is changing. The development of the Hybrid Involute Profile exploits involutometry relationships and properties. The derivation of the Hybrid Involute Profile along with validation case studies are presented.
Designing Product Families With Competition: A Design for Market Systems Approach
Authors: Karimian Peyman , Herrmann Jeffrey W.
Published: July 2010

Manufacturing firms use product families to provide variety while maintaining economies of scale to improve manufacturing productivity. Designing a successful product family requires consideration of both customer preferences and the competition. This paper presents a design for market systems approach to product family design and solves the problem of designing a product family when the competition is simultaneously designing its product family. In particular, the problem is formulated as a two-player zero-sum game. Our analysis of this problem shows that it can be separated into multiple subproblems whose solution provides an optimal solution to the original problem. The paper presents an example to illustrate the approach.
Early Design Modeling and Simulation of Behaviors: Case Study of Mobile Work Machine
Authors: Brace William , Coatane´a Eric , Kauranne Heikki , Heiska Matti
Published: July 2010

The early evaluation of a proposed function structure for a product and also, the possibility to expose the potential failures related to this provides that the design process can be modeled in its entirety. However, so far there are no existed suitable models for the early phase of design process. This article presents an integrated approach aimed to explore the behaviors of concept designs in the early design phase. The approach is founded on a combination of Petri net, π-numbers, qualitative physics principles and Design Structure Matrix. The final aim is to implement this method on the SysML modeling language to integrate a simulation approach that is initially not standardized in the language. A second interest of the approach is to provide a coherent simulation framework that can be used as a reference to verify the coherency of other simulation models further in the design process.
Separating Design Optimization Problems for Bounded Rational Designers
Authors: Herrmann Jeffrey W.
Published: July 2010

This paper presents a method for assessing the quality of progressive design processes that seek to maximize the profitability of the product that is being designed. The proposed approach uses separations, a type of problem decomposition, to model progressive design processes. The subproblems in the separations correspond roughly to phases in the progressive design processes. We simulate the choices of a bounded rational designer for each subproblem using different search algorithms. We consider different types and versions of these search processes in order to determine if the results are robust to the decision-making model. We use a simple two-variable problem to help describe the approach and then apply the approach to assess motor design processes. Methods for assessing the quality of engineering design processes can be used to guide improvements to engineering design processes and generate more valuable products.
Precise Motion Control of a Piezoelectric Microgripper for Microspectrometer Assembly
Authors: Rabenorosoa Kanty , Cle´vy Ce´dric , Lutz Philippe , Das Aditya N. , Murthy Rakesh , Popa Dan
Published: July 2010

The Fourier Transform (FTIR) microspectrometer discussed in this paper is an example of a complex Micro-Opto-Electro-Mechanical System (MOEMS) configured as an optical bench on a chip. It is an important benchmark application for microtechnology due to increased demands for the use of miniature wavelength detection instruments in bio, nano and material science. This device can be manufactured using automated microassembly and precision alignment of hybrid silicon and glass components, and in particular, of a micro-beamsplitter cube along 3 rotational degrees of freedom. In this paper, a piezoelectric microgripper with four degrees of freedom was attached to a precision robot in order to enhance its dexterity and align the beamsplitter to arcsecond angular tolerance. The modeling and control of the microgripper, and the alignment algorithm utilizing a novel spot-Jacobian servoing technique are discussed. Experimental results obtained during joint on-going work in Texas and in France are presented, demonstrating the advantage of using the microgripper for optical alignment of the microspectrometer.
Period-Doubling Bifurcations in Atomic Force Microscopy
Authors: Dick Andrew J. , Huang Wei
Published: July 2010

The dynamic response of an atomic force microscope cantilever probe is studied for off-resonance excitation and interactions with a soft silicone rubber material. The dynamic response of the probe is simulated using a three-mode approximation of the Euler-Bernoulli beam model for excitation at two-and-a-half times the probe’s fundamental frequency. These simulations are conducted in order to reproduce the period-doubling bifurcation experimentally observed in the response of the probe of a commercial atomic force microscope. In order to duplicate this behavior, parameters within the surface force model are tuned to account for variations in the characteristics of the sample material. Through this work, the relationship between the sample material’s effective stiffness and the response behavior of the probe are studied in an effort to develop the means to identify the local material properties of a sample by characterize the nonlinear response of the probe.
Tools for Project-Based Active Learning of Amorphous Systems Design: Scenario Prototyping and Cross Team Peer Evaluation
Authors: Ishii Kosuke , Kim Sun K. , Fowler Whitfield , Maeno Takashi
Published: July 2010

Whereas team project-based learning of engineering design has attracted wide acceptance, it is still rare to see a curriculum that addresses high level societal needs involving diverse students with a wide range of practical experience. Such a curriculum should develop a shared understanding of the use of scenarios for amorphous products and a process to objectively evaluate the project progress while the design concepts mature. This paper describes two key tools that respond to these challenges: 1) scenario prototyping and 2) cross-team project scorecarding. These tools evolved through a collaborative curriculum development of Keio University, MIT, and Stanford in the development of the Active Learning Project Sequence (ALPS), a capstone experience for Keio’s new Graduate School of System Design and Management (SDM). ALPS selected a theme from the “Voice of Society,” according to which the project teams generated solution scenarios, identified requirements, and described the proposed system using appropriate prototypes of not only hardware but other amorphous means as well. The twelve ALPS teams in 2008 addressed the theme “Enhancing the Lives of Seniors in Japan,” which led to more specific scenarios. The paper gives an overview of the ALPS workshop sequence, and describes in detail two key learning modules that were essential in integrating the multi-disciplinary teams: a) scenario prototyping and b) cross-team project scorecarding. These methods are going through further trials in Stanford’s own Design for Manufacturability curriculum involving 10 project teams in the US and Japan.
Analysis of Avoided Carbon-Dioxide Due to Photovoltaic and Wind Turbine Technologies Displacing Electrical Peaking Facilities
Authors: Kelly Jarod C. , Sivaraman Deepak , Keoleian Gregory A.
Published: July 2010

Many studies that examine the impact of renewable energy installations on avoided carbon-dioxide utilize national, regional or state averages to determine the predicted carbon-dioxide offset. The approach of this computational study was to implement a dispatching strategy in order to determine precisely which electrical facilities would be avoided due to the installation of renewable energy technologies. This study focused on a single geographic location for renewable technology installation, San Antonio, Texas. The results indicate an important difference between calculating avoided carbon-dioxide when using simple average rates of carbon-dioxide emissions and a dispatching strategy that accounts for the specific electrical plants used to meet electrical demands. The avoided carbon-dioxide due to renewable energy technologies is overestimated when using national, regional and state averages. This occurs because these averages include the carbon-dioxide emission factors of electrical generating assets that are not likely to be displaced by the renewable technology installation. The study also provides a comparison of two specific renewable energy technologies: photovoltaics (PV) and wind turbines. The results suggest that investment in PV is more cost effective for the San Antonio location. While the results are only applicable to this location, the methodology is useful for evaluating renewable technologies at any location.
Ceramic Composite Diesel Filter Trap
Authors: Deshpande Nishikant V. , Kongre Suhas C. , Deshpande Piyush N. , Indani Mahul , Singh Rajan
Published: July 2010

Diesel engine is a major source of power of the future but the major growing concern is the emissions of nitrogen oxides and diesel particulates. This work deals with the particulate emission control of diesel engine exhaust using ceramic filter. The selection of CFT with suitable size, geometry, cell density, wall thickness and microstructure becomes most important. In order to achieve required particulate matter emission limits and lower backpressure, optimization of porosity, pore size distribution, mean pore size and pore connectivity in CFT is crucial. CFT are developed and tested on the basis of porosity, diameter and length of CFT with necessary recommended trials. Further experiments were carried out to understand the effect of porosity, diameter and length of CFT on the back pressure, rate of back pressure rise, filtration efficiency and break power of diesel engine. The investigation of the research work provides adequate relevant information about the development of ceramic type ceramic filter trap (CFT) with naturally available material and effect of CFT on particulate matter concentration and on engine performance. Use of CFT reduced smoke drastically without increasing back pressure beyond tolerable back pressure limit. Performance of developed CFT was compared with established CFT and matches with it. Cost of developed CFT is the distinct advantage which will promote cottage industries in undeveloped nations, and provide rural employment.
Design for Lifecycle Cost Using Time-Dependent Reliability
Authors: Singh Amandeep , Mourelatos Zissimos P. , Li Jing
Published: July 2010

Reliability is an important engineering requirement for consistently delivering acceptable product performance through time. As time progresses, the product may fail due to time phenomena such as time-dependent operating conditions, component degradation, etc. The degradation of reliability with time may increase the lifecycle cost due to potential warranty costs, repairs and loss of market share. In design for lifecycle cost, we must account for product quality, and time-dependent reliability. Quality is a measure of our confidence that the product conforms to specifications as it leaves the factory. Reliability depends on 1) the probability that the system will perform its intended function successfully for a specified interval of time (no hard failure), and 2) on the probability that the system response will not exceed an objectionable by the customer or operator, threshold for a certain time period (no soft failure). Quality is time-independent, and reliability is time-dependent. This article presents a design methodology to determine the optimal design of time-dependent, multi-response systems, by minimizing the cost during the life of the product. The conformance of multiple responses is treated in a series-system fashion. The lifecycle cost includes a production, an inspection, and an expected variable cost. All costs depend on quality and/or reliability. The key to our approach is the calculation of the so-called system cumulative distribution function (time-dependent probability of failure). For that we use an equivalent time-invariant “composite” limit state which is accurate for monotonic or non-monotonic in time, systems. Examples highlight the calculation of the cumulative distribution function and the design methodology for lifecycle cost.
Design of a Biped Robot With Torsion Springs at the Joints for Reduced Energy Consumption During Walk
Authors: Singh Santosh Pratap , Dutta Ashish , Saxena Anupam
Published: July 2010

Biped robots have multiple degrees of freedom for walking and hence they consume a lot of energy. In this paper it is proposed that adding torsion springs at the joints of an 8 DOF biped will lead to reduced energy consumption during walk. First the dynamic equations of motion of the biped robot are obtained incorporating the torsion springs at the joints. Using the dynamic model the total energy consumed during walk was evaluated for a single step. A Genetic Algorithm (GA) based algorithm was developed for finding the energy optimal trajectory during gait by comparing all the possible trajectories. It is first proved that addition of torsion springs at the joints lead to reduction of energy consumption as compared to a biped with no springs. All the gait parameters were then optimized to get the optimum values for the spring constants at each joint, reference angle of springs and length of each step. It is proved that using these optimal parameters the proposed biped robot consumes the least energy.
Level Set-Based Topology Optimization Method for Thermal Problems Considering Design-Dependent Boundary Effects
Authors: Yamada Takayuki , Nishiwaki Shinji , Iga Atsuro , Izui Kazuhiro , Yoshimura Masataka
Published: July 2010

This paper proposes a new level set-based topology optimization method for thermal problems that deal with generic heat transfer boundaries including design-dependent boundary conditions, based on the level set method and the concept of the phase field theory. First, a topology optimization method using a level set model incorporating a fictitious interface energy derived from the concept of the phase field theory is briefly discussed. Next, a generic optimization problem for thermal problems is formulated based on the concept of total potential energy. An optimization algorithm that uses the Finite Element Method when solving the equilibrium equation and updating the level set function is then constructed. Finally, several three-dimensional numerical examples are provided to confirm the utility and validity of the proposed topology optimization method.
On the Primary Resonance of an Electrostatically Actuated MEMS Using the Homotopy Perturbation Method
Authors: Mojahedi Mahdi , Moghimi Zand Mahdi , Ahmadian Mohammad Taghi
Published: July 2010

In this paper, primary resonance of a double-clamped microbeam has been investigated. The Microbeam is predeformed by a DC electrostatic force and then driven to vibrate by an AC harmonic electrostatic force. Effects of midplane stretching, axial loads and damping are considered in modeling. Galerkin’s approximation is utilized to convert the nonlinear partial differential equation of motion to a nonlinear ordinary differential equation. Afterward, a combination of homotopy perturbation method and the method of multiple scales are utilized to find analytic solutions to the steady-state motion of the microbeam, far from pull-in. The effects of different design parameters on dynamic behavior are discussed. The results obtained by the presented method are validated by comparing with literature.
Geometric Optimization of Spatial Multimaterial Compliant Mechanisms and Structures Using Three-Dimensional Multilayer Wide Curves
Authors: Zhou Hong , Ting Kwun-Lon
Published: July 2010

Three-dimensional multilayer wide curves are spatial curves with variable cross sections and multiple materials. This paper introduces a geometric optimization method for spatial multimaterial compliant mechanisms and structures by using three-dimensional multilayer wide curves. In this paper, every multimaterial connection is represented by a three-dimensional multilayer wide curve and the whole spatial multimaterial compliant mechanism or structure is modeled as a set of connected three-dimensional multilayer wide curves. The geometric optimization of a spatial multimaterial compliant mechanism or structure is considered as the optimal selection of control parameters of the corresponding three-dimensional multilayer wide curves. The deformation and performance of spatial multimaterial compliant mechanisms and structures are evaluated by the isoparametric degenerate-continuum nonlinear finite element procedure. The problem-dependent objectives are optimized and the practical constraints are imposed during the optimization process. The optimization problem is solved by the MATLAB constrained nonlinear programming algorithm. The effectiveness of the proposed geometric optimization procedure is verified by the demonstrated examples.
Considering the Ability for Nonsingular Transitions of Assembly Mode for Dimensional Synthesis
Authors: Altuzarra Oscar , Petuya Vi´ctor , Uri´zar Mo´nica , Herna´ndez Alfonso
Published: July 2010

An important difficulty in the design of parallel manipulators is their reduced practical workspace, due mainly to the existence of a complex singularity locus within the workspace. The workspace is divided into singularity-free regions according to assembly modes and working modes, and the dimensioning of parallel manipulators aims at the maximization of those regions. It is a common practice to restrict the manipulator’s motion to a specific singularity-free region. However, a suitable motion planning can enlarge the operational workspace by means of transitions of working mode and/or assembly mode. In this paper, the authors present an analytical procedure for obtaining the loci of cusp points of a parallel manipulator as algebraic expressions of its dimensional parameters. The purpose is to find an optimal design for non-singular transitions to be possible.
Virtual Supply Chain Configuration for Product Families: Conceptualization and Formalism
Authors: Xu Qianli , Jiao Jianxin Roger , Helo Petri
Published: July 2010

The rationale of product families for mass customization has attracted much attention from both academia and industry alike. While the product family strategy facilitates product differentiation and customization, it inevitably leads to a high variety issue in the downstream fulfillment process. In particular, when assembly-to-order and outsourcing become common practices, the supply chain decisions are deemed to be very complicated in order to accommodate the diverse product and process variants associated with product families. With focus on variety management, this paper proposes a virtual supply chain (VSC) configuration concept. The general gist is to manage various supply chain variants under a generic umbrella. It emphasizes the conceptualization and modeling of VSC to enhance the power of variety handling, with respect to supply chains, as well as products and processes. A domain-based reference model is employed to identify and coordinate the decision factors of supply chains. These decision factors are used to model the VSC based on formal semantics and object-oriented modeling techniques. The management of supply chain variety is formulated as the VSC configuration problem, and is coped with variety handlers and their states. A case study of electrical motor global supply chains is reported. It is demonstrated that the generic characteristics of VSC excel in coordinating the decisions regarding product, process and supply chains towards mass customization.
A Mathematical-Numerical Model to Calculate Load Distribution, Contact Stiffness and Transmission Error in Involute Spur Gears
Authors: Mohammadpour Mehdi , Mirzaee Iraj , Khalilarya Shahram
Published: July 2010

This paper firstly presents a mathematical model in order to calculate the load distribution, single contact stiffness and meshing stiffness as well as transmission error. in this way, there is no need to use finite element like methods and also the calculation time is dramatically reduced. Presented method is based on definition of a statically undetermined problem that is formulated using energy method. Some assumptions considered to convert this problem to a statically determined problem and get the mathematical models. Then a numerical method is employed in order to solve the mathematical model using a double iteration flowchart to close the problem. This model is flexible to adapt for any modification in spur gear profile geometry. Finally, this model is verified using previous works that have been utilized finite element and experimental model.
Slider Cranks as Compatibility Linkages for Parameterizing Center Point Curves
Authors: Myszka David H. , Murray Andrew P.
Published: July 2010

In synthesizing a planar 4R linkage that can achieve four positions, the fixed pivots are constrained to lie on a center-point curve. It is widely known that the curve can be parameterized by a 4R compatibility linkage. In this paper, a slider crank is presented as a suitable compatibility linkage to generate the centerpoint curve. Further, the center-point curve can be parametrized by the crank angle of a slider crank linkage. It is observed that the center-point curve is dependent on the classification of the slider crank. Lastly, a direct method to calculate the focus of the center-point curve is revealed.
Reactionless Two-Degree-of-Freedom Planar Parallel Mechanism With Variable Payload
Authors: Lecours Alexandre , Gosselin Cle´ment
Published: July 2010

A reactionless mechanism is one which does not exert any reaction force or moment on its base at all times, for any arbitrary trajectory of the mechanism. This paper addresses the static and dynamic balancing of a two-degree-of-freedom parallel planar mechanism (five-bar mechanism). A simple and effective adaptive balancing method is presented that allows the mechanism to maintain the reactionless condition for a range of payloads. Important proofs concerning the balancing of five-bar mechanisms are also presented. The design of a real mechanism where parallelogram linkages are used to produce pure translations at the end-effector is also presented. Finally, using dynamic simulation software, it is shown that the mechanism is reactionless for arbitrarily chosen trajectories and for a variety of payloads.
Reliability-Based Design Optimization With Confidence Level Under Input Model Uncertainty
Authors: Noh Yoojeong , Choi K. K. , Lee Ikjin , Gorsich David , Lamb David
Published: July 2010

For obtaining correct reliability-based optimum design, an input model needs to be accurately estimated in identification of marginal and joint distribution types and quantification of their parameters. However, in most industrial applications, only limited data on input variables is available due to expensive experimental testing costs. The input model generated from the insufficient data might be inaccurate, which will lead to incorrect optimum design. In this paper, reliability-based design optimization (RBDO) with the confidence level is proposed to offset the inaccurate estimation of the input model due to limited data by using an upper bound of confidence interval of the standard deviation. Using the upper bound of the confidence interval of the standard deviation, the confidence level of the input model can be assessed to obtain the confidence level of the output performance, i.e. a desired probability of failure, through the simulation-based design. For RBDO, the estimated input model with the associated confidence level is integrated with the most probable point (MPP)-based dimension reduction method (DRM), which improves accuracy over the first order reliability method (FORM). A mathematical example and a fatigue problem are used to illustrate how the input model with confidence level yields a reliable optimum design by comparing it with the input model obtained using the estimated parameters.