bluuebunny/crossref_metadata_2025 huggingface dataset:
Fine Particulate Formation During Switchgrass/Coal Cofiring
Authors: Blevins Linda G. , Cauley Thomas H.
Published: June 2005

Experiments to examine the effects of biomass/coal cofiring on fine particle formation were performed in the Sandia Multi-Fuel Combustor using fuels of pure coal, three combinations of switchgrass and coal, and pure switchgrass. For this work, fine particles with aerodynamic diameter between 10 nm and 1 μm were examined. A constant solid-fuel thermal input of 8 kW was maintained. The combustion products were cooled from 1200 to 420°C during passage through the 4.2 m long reactor to simulate the temperatures experienced in the convection pass of a boiler. Fine particle number densities, mass concentrations, and total integrated number and mass concentrations at the reactor exit were determined using a scanning mobility particle sizer. The fine particle number concentrations for cofiring were much higher than those achieved with dedicated coal combustion. However, the total integrated mass concentration of particles remained essentially constant for all levels of cofiring from 0% coal to 100% coal. The constant mass concentration is significant because pending environmental regulations are likely to be based on particle mass rather than particle size.
Circular-Hinge Line Element for Finite Element Analysis of Compliant Mechanisms
Authors: Lobontiu Nicolae , Garcia Ephrahim
Published: June 2005

A three-node six degree-of-freedom per-node line element that is sensitive to axial, bending, and torsional loading is introduced to model single-axis right circular hinges of constant width that are utilized in compliant mechanisms. The Timoshenko model is applied for bending because this particular configuration is virtually short, and provisions are taken that the element is shear-locking free. The Saint Venant theory, which includes warping, is utilized to model torsion of the variable rectangular cross-section circular hinge. The principle of minimum total potential energy is employed to formulate the elemental stiffness and mass matrices, as well as the elemental nodal vector. Static force deflection and modal simulation that are performed based on this finite element model produce results that are in agreement with simulation by commercially available finite element software. The three-node line element is also compared to an analytical model in terms of stiffness and the results are again concurring.
A Three Degree-of-Freedom Model for Self-Retracting Fully Compliant Bistable Micromechanisms
Authors: Masters Nathan D. , Howell Larry L.
Published: June 2005

A three degree-of-freedom (3DOF) pseudo-rigid-body model (PRBM) has been developed and used in the design of a new class of self-retracting fully compliant bistable micromechanism (SRFBM). The SRFBM provides small-displacement linear travel bistability and is suitable for low-power microswitching applications. The design process involved a combination of single and multiple degree-of-freedom PRBM and finite element models to quickly proceed from a concept rigid-body mechanism to fully compliant fabrication-ready geometry. The 3DOF model presented here was developed to more accurately model the behavior of the tensural pivots—a new class of compliant segment used to avoid combined compressive loading of flexible segments. Four SRFBM designs were fabricated and tested for bistability, on-chip actuation, critical force, and fatigue tests. These tests validate the models used in the design process and demonstrate the functionality and reliability of the SRFBM.
Four-Bar Linkage Mechanism for Insectlike Flapping Wings in Hover: Concept and an Outline of Its Realization
Authors: Z˙bikowski Rafał , Galin´ski Cezary , Pedersen Christopher B.
Published: June 2005

This paper describes the concept of a four-bar linkage mechanism for flapping wing micro air vehicles and outlines its design, implementation, and testing. Micro air vehicles (MAVs) are defined as flying vehicles ca. 150 mm in size (handheld), weighing 50–100 g, and are developed to reconnoiter in confined spaces (inside buildings, tunnels, etc.). For this application, insectlike flapping wings are an attractive solution and, hence, the need to realize the functionality of insect flight by engineering means. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forward and backward. During this motion, the wing tip approximately traces a figure eight and the wing changes the angle of attack (pitching) significantly. The aim of the work described here was to design and build an insectlike flapping mechanism on a 150 mm scale. The main purpose was not only to construct a test bed for aeromechanical research on hover in this mode of flight, but also to provide a precursor design for a future flapping-wing MAV. The mechanical realization was to be based on a four-bar linkage combined with a spatial articulation. Two instances of idealized figure eights were considered: (i) Bernoulli’s lemniscate and (ii) Watt’s sextic. The former was found theoretically attractive, but impractical, while the latter was both theoretically and practically feasible. This led to a combination of Watt’s straight-line mechanism with a drive train utilizing a Geneva wheel and a spatial articulation. The actual design, implementation, and testing of this concept are briefly described at the end of the paper.
Economic and Scenario Analyses of New Gas Turbine Combined Cycles With No Emissions of Carbon Dioxide
Authors: Gabbrielli R. , Singh R.
Published: June 2005

In this paper economic and scenario analyses of new gas turbine combined cycles with no emissions of carbon dioxide CO2 and nitrogen oxides are described. The cycles, already presented in a recent paper (ASME GT 2002-30117), have water/steam as a working fluid, the compression phase both in liquid and vapor phase, the internal combustion between pure oxygen O2 and chemically heated natural gas-based syngas, and the CO2 capture and sequestration by water condensation from the exhaust gas. The aim of the economic analyses is to estimate the investment per MW and the levelized discounted cost of the electricity (COE) produced by a power plant based on the cycles proposed here in comparison with a standard reference combined cycle power plant (SRCC). To evaluate the equipment costs, several cost functions of the most important operative parameters have been introduced and tuned with the actual data. Using the least square regression technique, explicit functions of the COE have been proposed to highlight the cheapest operative conditions with a derivative approach. Moreover, a wide scenario analysis has been carried out, varying the most important investment parameters, as, for example, the discount rate. In particular, some maps of the COE and break-even carbon tax (BECT) behavior have been constructed to test the importance of the market uncertainty on the economic results obtained. Finally, the possible technological progress effect on the BECT with a cost reduction of some innovative equipment and the O2 production has been investigated in depth with the 2k factorial design scenario analysis. The O2 production has resulted as the most important parameter from an economic point of view.
Online Combustor Stability Margin Assessment Using Dynamic Pressure Data
Authors: Lieuwen Tim
Published: June 2005

This paper describes a strategy for determining a combustor’s dynamic stability margin. Currently, when turbines are being commissioned or simply going through day to day operation, the operator does not know how the stability of the system is affected by changes to fuel splits or operating conditions unless, of course, pressure oscillations are actually present. We have developed a methodology for ascertaining the stability margin from dynamic pressure data that does not require external forcing and that works even when pressure oscillations have very low amplitudes. This method consists of signal processing and analysis that determines a real-time measure of combustor damping. When the calculated damping is positive, the combustor is stable. As the damping goes to zero, the combustor approaches its stability boundary. Changes in the stability margin of each of the combustor’s stable modes due to tuning, aging, or environmental changes can then be monitored through an on-line analysis of the pressure signal. This paper outlines the basic approach used to quantify acoustic damping and demonstrates the technique on combustor test data.
Experiment on Gas Ingestion Through Axial-Flow Turbine Rim Seals
Authors: Roy R. P. , Feng J. , Narzary D. , Paolillo R. E.
Published: June 2005

It has been suggested by researchers that ingestion, through rim seals, of mainstream gas into axial-flow turbine disk cavities is a consequence of the prevailing unsteady three-dimensional flow field. The cause–effect relationship is complex—to help understand it, experiments were performed in a model single-stage turbine rig using two different vane-blade configurations. Selected measurements from one of the configurations were reported earlier (1999–2001). The second configuration is new, featuring smaller numbers of vanes and blades and a larger vane turning angle. Selected measurements are presented and compared to those from the first configuration. The measurements include unsteady and rotor revolution time-average static pressure spatial distributions, and spatial distribution, in the rotor-stator cavity, of time-average ingestion. The parameters in the experiments were the main airflow rate, the purge/seal airflow rate, and the rotor speed. Unsteady three-dimensional CFD simulation may be helpful in identifying the roles of the many intertwined phenomena in the ingestion process.
Optimal Operational Planning of Cogeneration Systems With Microturbine and Desiccant Air Conditioning Units
Authors: Gamou Satoshi , Ito Koichi , Yokoyama Ryohei
Published: June 2005

Economic and energy-saving characteristics of cogeneration systems with microturbine and desiccant air-conditioning units are investigated on system operational planning. An optimization approach is adopted to rationally evaluate these characteristics. In this approach, on/off and rated/part load status of operation of equipment and energy flow rates are determined so as to minimize the hourly energy charge subject to satisfaction of energy demand requirements. In this optimization problem, performance characteristics of the microturbine and desiccant air-conditioning units are modeled in consideration of the influence due to ambient air temperature. Moreover, the influence due to ambient air humidity is also considered in the desiccant air-conditioning unit using the psychrometric diagram. The implementation of the numerical analysis method, discussed in this paper, to two cogeneration systems, clearly shows economic and operational benefits of using desiccant air-conditioning.
Frequency Response Analysis of an Actively Lubricated Rotor/Tilting-Pad Bearing System
Authors: Nicoletti Rodrigo , Santos Ilmar Ferreira
Published: June 2005

In the present paper, the dynamic response of a rotor supported by an active lubricated tilting-pad bearing is investigated in the frequency domain. The theoretical part of the investigation is based on a mathematical model obtained by means of rigid body dynamics. The oil film forces are inserted into the model by using two different approaches: (a) linearized active oil film forces and the assumption that the hydrodynamic forces and the active hydraulic forces can be decoupled, and (b) equivalent dynamic coefficients of the active oil film and the solution of the modified Reynolds equation for the active lubrication. The second approach, based on the equivalent dynamic coefficients, leads to more accurate results because it includes the frequency dependence of the active hydraulic forces. Theoretical and experimental results reveal the feasibility of reducing resonance peaks by using the active lubricated tilting-pad bearing. By applying a simple proportional controller, it is possible to reach 30% reduction of the resonance peak associated with the first rigid body mode shape of the system. One of the most important consequences of such a vibration reduction in rotating machines is the feasibility of increasing their operational range by attenuating resonance peaks and reducing vibration problems.
Compliant Joint Design Principles for High Compressive Load Situations
Authors: Guérinot Alexandre E. , Magleby Spencer P. , Howell Larry L. , Todd Robert H.
Published: June 2005

Buckling failure has been a major obstacle in designing compliant joints in high compression applications. This paper describes two principles, isolation and inversion, that can be successfully applied to many compliant joints to increase their ability to withstand high compressive loads by avoiding buckling-prone loading conditions. Isolation and inversion give rise to a new breed of compliant joints called high compression compliant mechanisms (HCCM). HCCMs have many of the inherent advantages of compliant mechanisms with the additional qualities of high load-bearing joints. This added robustness in compression can be achieved without adversely affecting the kinematic behavior of the joint.
Protofold: A Successive Kinetostatic Compliance Method for Protein Conformation Prediction
Authors: Kazerounian Kazem , Latif Khalid , Alvarado Carlos
Published: June 2005

This paper presents an efficient and novel computational protein prediction methodology called kineto-static compliance method. Successive kineto-static fold compliance is a methodology for predicting a protein molecule’s motion under the effect of an inter-atomic force field without the need for molecular-dynamic simulation. Instead, the chain complies under the kineto-static effect of the force field in such a manner that each rotatable joint changes by an amount proportional to the effective torque on that joint. This process successively iterates until all of the joint torques have converged to a minimum. This configuration is equivalent to a stable, globally optimized potential energy state of the system or, in other words, the final conformation of the protein. This methodology is implemented in a computer software package named PROTOFOLD. In this paper, we have used PROTOFOLD to predict the final conformation of a small peptide chain segment, an alpha helix, and the Triponin protein chains from a denatured configuration. The results show that torques in each joint are minimized to values very close to zero, which demonstrates the method’s effectiveness for protein conformation prediction.
Nano-Kinematics for Analysis Of Protein Molecules
Authors: Kazerounian Kazem , Latif Khalid , Rodriguez Kimberly , Alvarado Carlos
Published: June 2005

Proteins are evolution’s mechanisms of choice. The study of nano-mechanical systems must encompass an understanding of the geometry and conformation of protein molecules. Proteins are open or closed loop kinematic chains of miniature rigid bodies connected by revolute joints. The Kinematics community is in a unique position to extend the boundaries of knowledge in nano biomechanical systems. In this work, we have presented a comprehensive methodology for kinematics notation and direct kinematics for protein molecules. These methods utilize the zero-position analysis method and draws upon other recent advances in robot manipulation theories. The procedures involved in finding the coordinates of every atom in the protein chain as a function of the dihedral and Rotamer angles are computationally the most efficient formulation developed to date. The notation and the methodologies of this paper are incorporated in the computer software package PROTOFOLD and will be made available to individuals interested in using it. PROTOFOLD is a software package that implements novel and comprehensive methodologies for ab initio prediction of the final three-dimensional conformation of a protein, given only its linear structure. In addition to the new kinematics methodologies mentioned above, we have also included all the basic kinematic parameter values that are needed in any kinematic analysis involving proteins. While these values are based on a body of knowledge recorded in the protein data bank, they are presented in a form conducive to kinematics.
Target Management in Complex System Design Using System Norms
Authors: Mahmoud H. , Kabamba P. , Ulsoy A. G. , Brusher G.
Published: June 2005

The problem of setting, balancing, and determining priorities of design targets among the subsystems constituting an engineering system, i.e., managing the targets, is addressed. A new norm-based benchmarking approach is proposed to relate the system-level design objectives to subsystem design targets. The proposed approach provides a systematic means of setting and balancing subsystem design targets to deliver the desired system performance and ranks the priorities of the subsystem targets. Furthermore, the use of system norms, rather than output signal norms, to quantify system and subsystem performance reduces the number of design targets in multi-input multi-output (MIMO) systems. The approach is illustrated on a vehicle example, consisting of a frame, body, and body mounts as the subsystems.
Analysis of Decomposability and Complexity for Design Problems in the
Context of Decomposition
Authors: Chen Li , Li Simon
Published: June 2005

The current practice in problem decomposition assumes that (i) design problems can be rationally decomposed a priori and (ii) decomposition can usefully result in complexity reduction a priori. However, these assumptions are not always true in reality. In response to this concern, this paper introduces the notions of decomposability and complexity to problem decomposition. In particular, a full scale of decomposability analysis and complexity analysis in the context of decomposition are presented along with approaches and algorithms. These new analyses not only address the viability and validity of decomposition, but also help achieve an optimal number of subproblems during decomposition, which is usually determined by trial and error or a priori. Furthermore, a procedure able to combine these new analyses into our two-phase decomposition framework is described. This effort leads to an enhanced decomposition method able to find the most appropriate decomposition solution to a complex design problem.
A Linear Beam Finite Element Based on the Absolute Nodal Coordinate Formulation
Authors: Kerkkänen Kimmo S. , Sopanen Jussi T. , Mikkola Aki M.
Published: June 2005

In this paper, a new two-dimensional shear deformable beam element based on the absolute nodal coordinate formulation is proposed. The nonlinear elastic forces of the beam element are obtained using a continuum mechanics approach, without employing a local element coordinate system. In this study, linear polynomials are used to interpolate both the transverse and longitudinal components of the displacement. This is different from other absolute nodal-coordinate-based beam elements where cubic polynomials are used in the longitudinal direction. The use of linear interpolation polynomials leads to the phenomenon known as shear locking. This defect is avoided through the adoption of selective integration within the numerical integration method. The proposed element is verified using several numerical examples. The results of the proposed element are compared to analytical solutions and the results for an existing shear deformable beam element. It is shown that by using the proposed element, accurate linear and nonlinear static deformations, as well as realistic dynamic behavior including the capturing of the centrifugal stiffening effect, can be achieved with a smaller computational effort than by using existing shear deformable two-dimensional beam elements.
Force Analysis of a Vibratory Bowl Feeder for Automatic Assembly
Authors: Silversides Richard , Dai Jian S , Seneviratne Lakmal
Published: June 2005

This paper investigates the vibratory bowl feeder for automatic assembly, presents a geometric model of the feeder, and develops force analysis, leading to dynamical modeling of the vibratory feeder. Based on the leaf-spring modeling of the three legs of the symmetrically arranged bowl of the feeder, and equating the vibratory feeder to a three-legged parallel mechanism, the paper reveals the geometric property of the feeder. The effects of the leaf-spring legs are transformed to forces and moments acting on the base and bowl of the feeder. Resultant forces are obtained based upon the coordinate transformation, and the moment analysis is produced based upon the orthogonality of the orientation matrix. This reveals the characteristics of the feeder, that the resultant force is along the z-axis and the resultant moment is about the z direction and further generates the closed-form motion equation. The analysis presents a dynamic model that integrates the angular displacement of the bowl with the displacement of the leaf-spring legs. Both Newtonian and Lagrangian approaches are used to verify the model, and an industrial case-based simulation is used to demonstrate the results.
Enhancing Discrete Choice Demand Modeling for Decision-Based
Design
Authors: Wassenaar Henk Jan , Chen Wei , Cheng Jie , Sudjianto Agus
Published: June 2005

Our research is motivated by the need for developing an approach to demand modeling that is critical for assessing the profit a product can bring under the decision-based design framework. Even though demand modeling techniques exist in market research, little work exists on demand modeling that addresses the specific needs of engineering design, in particular, that facilitates engineering decision making. In this work, we enhance the use of discrete choice analysis to demand modeling in the context of decision-based design. The consideration of a hierarchy of product attributes is introduced to map customer desires to engineering design attributes related to engineering analyses. To improve the predictive capability of demand models, the Kano method is employed to provide econometric justification when selecting the shape of the customer utility function. A (passenger) vehicle engine case study, developed in collaboration with the market research firm, J. D. Power & Associates, and the Ford Motor Company, is used to demonstrate the proposed approaches.
A Self-Actuating Traction-Drive Speed Reducer
Authors: Flugrad Donald R. , Qamhiyah Abir Z.
Published: June 2005

Traction-drive speed reducers offer certain advantages over geared speed reducers. In particular, they generally run quieter than geared units and provide an opportunity for higher efficiency by eliminating sliding motion between contacting elements. In order to generate a sufficiently high output torque, some means must be provided to create a normal force between the rolling elements. This normal force, along with the friction coefficient, enables the device to transmit torque from one rolling member to the next. The speed reducer proposed here is designed so that the configuration of the rolling elements creates the needed normal force in response to the torque exerted back on the system by the downstream loading. Thus the device is self-actuating. Since the normal force is only present when needed, the rolling elements of the device can readily be disengaged, thus eliminating the need for a separate clutch in the drive system. This feature can be exploited to design a transmission with several distinct speed ratios that can be engaged and disengaged in response to changing speed requirements.
The Curve of Striction of the Bennett Loop’s Fixed Axode
Authors: Baker J. Eddie
Published: June 2005

In previous work, the algebraic representation of a fixed axode of the Bennett linkage has been revealed as extraordinarily cumbersome. In this sequel we use properties of the ruled surface to determine the central point of a typical generator of the axode and hence its curve of striction as the intersection of two comparatively simple surfaces. Because of its special significance in this case, we also obtain the equation to the central tangent surface. A feature of the investigation is the direct employment of screw vectors in dual format rather than unit line vectors.
On Systematic Errors of Two-Dimensional Finite Element Modeling of Right Circular Planar Flexure Hinges
Authors: Zettl B. , Szyszkowski W. , Zhang W. J.
Published: June 2005

This paper discusses the finite element method (FEM) based modeling of the behavior of typical right circular flexure hinges used in planar compliant mechanisms. Such hinges have traditionally been approximated either by simple beams in the analytical approach or very often by two-dimensional (2D) plane stress elements when using the FEM. The three-dimensional (3D) analysis presented examines these approximations, focusing on systematic errors due to 2D modeling. It is shown that the 2D models provide only the lower (assuming the plane stress state) or the upper (assuming the plane strain state) limits of the hinge’s stiffness. The error of modeling a particular hinge by 2D elements (with either the plane stress or the plane strain assumptions) depends mainly on its depth-to-height ratio and may reach up to about 12%. However, this error becomes negligible for hinges with sufficiently high or sufficiently low depth-to-height ratios, in which either the plane strain or stress states dominate respectively. It is also shown that the computationally intensive 3D elements can be replaced, without sacrificing accuracy, by numerically efficient 2D elements if the material properties are appropriately manipulated.
A Method for Estimating Servomotor Parameters of a Parallel Robot for Rapid Pick-and-Place Operations
Authors: Huang Tian , Mei Jiangping , Li Zhanxian , Zhao Xueman , Chetwynd Derek G.
Published: June 2005

By taking a 2-DOF high-speed translational parallel manipulator as an object of study, this paper presents an approach that enables the servomotor parameters of parallel robots for pick-and-place operations to be estimated in an effective manner using the singular value decomposition. These parameters include the moment of inertia, speed, torque, and power of the motor required for producing the specified velocity and acceleration of the end effector. An example is given to determine these parameters of a device for the rechargeable battery quality inspection.
Platform Selection Under Performance Bounds in Optimal Design of Product Families
Authors: Fellini Ryan , Kokkolaras Michael , Papalambros Panos , Perez-Duarte Alexis
Published: June 2005

Designing a family of product variants that share some components usually requires a compromise in performance relative to the individually optimized variants due to the commonality constraints. Choosing components for sharing may depend on what performance losses can be tolerated. In this article an optimal design problem is formulated to choose product components to be shared without exceeding user-specified bounds on performance. This enables the designer to control tradeoffs and obtain optimal product family designs for maximizing commonality at different levels of acceptable performance. A family of automotive body side frames is used to demonstrate the approach.
Optimal Tooth Modifications in Hypoid Gears
Authors: Simon Vilmos
Published: June 2005

A method for the determination of optimal tooth modifications in hypoid gears based on improved load distribution and reduced transmission errors is presented. The modifications are introduced into the pinion tooth surface by using a cutter with bicircular profile and optimal diameter. In the optimization of tool parameters the influence of shaft misalignments of the mating members is included. As the result of these modifications a point contact of the meshed teeth surfaces appears instead of line contact; the hypoid gear pair becomes mismatched. By using the method presented in (Simon, V., 2000, “Load Distribution in Hypoid Gears,” ASME J. Mech. Des., 122, pp. 529–535) the influence of tooth modifications introduced on tooth contact and transmission errors is investigated. Based on the results that was obtained the radii and position of circular tool profile arcs and the diameter of the cutter for pinion teeth generation were optimized. By applying the optimal tool parameters, the maximum tooth contact pressure is reduced by 16.22% and the angular position error of the driven gear by 178.72%, in regard to the hypoid gear pair with a pinion manufactured by a cutter of straight-sided profile and of diameter determined by the commonly used methods.
Synthesis of Compliant Mechanisms for Path Generation using Genetic Algorithm
Authors: Saxena Anupam
Published: June 2005

In this paper is described a procedure to synthesize the optimal topology, shape, and size of compliant continua for a given nonlinear output path. The path is prescribed using a finite number of distinct precision points much in accordance with the synthesis for path generation in traditional kinematics. Geometrically nonlinear analysis is employed to model large displacements of the constituent members. It is also essential to employ nonlinear analysis to allow the output port to negotiate the prescribed path accurately. The topology synthesis problem is addressed in its original binary form in that the corresponding design variables are only allowed to assume values of “0” for no material and “1” for the material present at a site in the design region. Shape and size design variables are modeled using continuous functions. Owing to the discrete nature of topology design variables, since gradient based optimization methods cannot be employed, a genetic algorithm is used that utilizes only the objective values to approach an optimum solution. A notable advantage of a genetic algorithm over its gradient based counterparts is the implicit circumvention of nonconvergence in the large displacement analysis, which is another reason why a genetic algorithm is chosen for optimization. The least squared objective is used to compare the design and desired output responses. To allow a user to specify preference for a precision point, individual multiple least squared objectives, same in number as the precision points are used. The multiple objectives are solved using Nondominated Sorting in Genetic Algorithm (NSGA-II) to yield a set of pareto optimal solutions. Thus, multiple solutions for compliant mechanisms can be obtained such that a mechanism can traverse one or some precision points among those specified more precisely. To traverse the entire path, a solution that minimizes the sum of individual least square objectives may be chosen. Synthesis examples are presented to demonstrate the usefulness of the proposed method that is capable of generating a solution that can be manufactured as is without requiring any interpretation.
Biologically Inspired Design Of Small Flapping Wing Air Vehicles Using Four-Bar Mechanisms And Quasi-steady Aerodynamics
Authors: Madangopal Rajkiran , Khan Zaeem A. , Agrawal Sunil K.
Published: June 2005

In this paper, the energetics of a flapping wing micro air vehicle is analyzed with the objective of design of flapping wing air vehicles. The salient features of this study are: (i) design of an energy storage mechanism in the air vehicle similar to an insect thorax which stores part of the kinetic energy of the wing as elastic potential energy in the thorax during a flapping cycle; (ii) inclusion of aerodynamic wing models using blade element theory and inertia of the mechanism using rigid body modeling techniques; (iii) optimization of parameters of the energy storage mechanism using the dynamic models so that the peak power input from the external actuators during a flapping cycle is minimized. A series of engineering prototypes based on these studies have been fabricated which justify the use of these mathematical techniques.
Topological Synthesis of Compliant Mechanisms Using Spanning Tree Theory
Authors: Zhou Hong , Ting Kwun-Lon
Published: June 2005

This paper introduces the spanning tree theory to the topological synthesis of compliant mechanisms, in which spanning trees connect all the vertices together using a minimum number of edges. A valid topology is regarded as a network connecting input, output, support, and intermediate nodes, which contains at least one spanning tree among the introduced nodes. Invalid disconnected topologies can be weeded out if no spanning tree is included. No further deformation analysis and performance evaluation is needed to invalidate disconnected topologies. Problem-dependent objectives are optimized for topological synthesis of compliant mechanisms. Constraints about maximum input displacement and force, maximum stress and overlapping connections are directly imposed during optimization process. The discrete optimization problem is solved by genetic algorithm with penalty function handling constraints. Two examples are given to verify the effectiveness of the proposed synthesis procedure.
Design of Large-Displacement Compliant Joints
Authors: Trease Brian P. , Moon Yong-Mo , Kota Sridhar
Published: June 2005

This paper investigates the drawbacks of typical flexure connectors and presents several new designs for highly effective, kinematically well-behaved compliant joints. A revolute and a translational compliant joint are proposed, both of which offer great improvements over existing flexures in the qualities of (1) a large range of motion, (2) minimal “axis drift,” (3) increased off-axis stiffness, and (4) a reduced stress-concentrations. Analytic stiffness equations are developed for each joint and parametric computer models are used to verify their superior stiffness properties. A catalog of design charts based on the parametric models is also presented, allowing for rapid sizing of the joints for custom performance. A joint range of motion has been calculated with finite element analysis, including stress concentration effects.
Biomedical Assist Devices and New Biomimetic Machines—A Short Perspective
Authors: Agrawal Sunil K. , Erdman Arthur G.
Published: June 2005

Over the last few decades, new engineering designs have made tremendous impact on the healthcare industry with solutions for diagnosis, treatment, and therapy of a wide range of medical conditions. In recent years, new designs of bio-inspired machines have been proposed for terrestrial and aerial applications. As one would expect, a detailed survey of these areas is impossible to accomplish in a few pages. Hence, this brief survey highlights three topics: (i) Gait rehabilitation machines, (ii) minimal invasive surgical machines, and (iii) flapping wing flying machines.
Dynamic Modeling of Compliant Mechanisms Based on the Pseudo-Rigid-Body Model
Authors: Yu Yue-Qing , Howell Larry L. , Lusk Craig , Yue Ying , He Mao-Gen
Published: June 2005

Based on the principle of dynamic equivalence, a new dynamic model of compliant mechanisms is developed using the pseudo-rigid-body model. The dynamic equation of general planar compliant mechanisms is derived. The natural frequency of a compliant mechanism is obtained in the example of a planar compliant parallel-guiding mechanism. The numerical results show the effectiveness and advantage of the proposed method compared with the methods of FEA and flexible mechanisms.
Kinematics and Workspace Analysis of Protein Based Nano-Actuators
Authors: Sharma G. , Badescu M. , Dubey A. , Mavroidis C. , Tomassone S. M. , Yarmush M. L.
Published: June 2005

In this paper, a novel nanoscale protein based nano actuator concept is described. Molecular kinematic computational tools are developed and included in our Matlab Biokinematics Toolbox to study the protein nanomotor’s performance using geometric criteria. The computational tools include the development of the molecular motor direct and inverse kinematics using the protein’s Denavit and Hartenberg parameters and the corresponding homogeneous transformation matrices. Furthermore, the workspace calculation and analysis of the protein motor is performed.
Spectroscopic Measurements of High Emissivity Materials Using Two-Dimensional Two-Color Thermometry
Authors: Tago Yuichiro , Akimoto Fumie , Kitagawa Kuniyuki , Arai Norio , Churchill Stuart W. , Gupta Ashwani K.
Published: June 2005

Radiative heat transfer characteristics from the surface of a substance coated with a high-emissivity material have been examined from the measured two-dimensional (2D) temperature distribution using two-color thermometry principle. The technique utilized a charge coupled device camera and optical filters having either wide or narrow wavelength bandpass filters. The results obtained were compared to evaluate the accuracy of the temperature measurements. The 2D emissivity distributions were also derived from the measured 2D temperature distributions. The results indicate that the substrate coated with high-emissivity material exhibit high emission of radiation, resulting in effective cooling. The enhanced emissivity of materials also results in improved radiative heat transfer in heating furnaces and other high-temperature applications. The emissivity measured with the wide-bandpass filters increased with temperature. Atmospheric absorption, mainly due to humidity, made a negligible contribution to the total spectral intensity and to the temperature measurements. The small discrepancies are attributed to the dependence of emissivity on wavelength. Thus, the use of narrow-bandpass filters in thermometry is advantageous over the wide-bandpass ones.
H 2 ∕ O 2 Cycles: Thermodynamic Potentialities and Limits
Authors: Gambini M. , Guizzi G. L. , Vellini M.
Published: June 2005

In this paper, the thermodynamic potentialities and limits of the H2∕O2 turbine cycles (afterward named only H2∕O2 cycles) are investigated. Starting from the conventional gas turbine and steam turbine technology, the paper qualitatively tackles problems related to a change of oxidizer and fuel: from these considerations, an internal combustion steam cycle is analyzed where steam, injected into the combustion chamber together with oxygen and hydrogen, is produced in a regenerative way and plays the important role of inert. A proper parametric analysis is then performed in order to evaluate the influence of the main working parameters on the overall performance of H2∕O2 cycles. All the results are carried out by neglecting the energy requirements for O2 and H2 production systems, but taking into account the work required by the O2 and H2 compression. This choice permits a great freedom in the definition of these thermodynamic cycles; moreover, it is possible to come to some general conclusions because the H2 and/or O2 production systems and their integrations with thermodynamic cycles do not have to be specified. Therefore, this paper can be framed in a context of centralized production of oxygen and hydrogen (by nuclear or renewable energy sources, for example) and their distribution as pure gases in the utilization place. By adopting some realistic assumptions, for example, a top temperature of 1350°C, the potentialities of H2∕O2 cycles are very limited: the net efficiency attains a value of about 50%. Instead, by adopting futurist assumptions, for example, a top temperature of 1700°C, a different H2∕O2 cycle scheme can be proposed and its performance becomes more interesting (the net efficiency is over 60%). The paper tackles the main thermodynamic and technological subjects of the H2∕O2 cycles: for example, it is underlined how the choice of the working parameters of these cycles strongly influences the attainable performance.
Influence of Pulsating Flow on Close-Coupled Catalyst Performance
Authors: Tsinoglou Dimitrios N. , Koltsakis Grigorios C.
Published: June 2005

Close coupling of automotive three-way catalytic converters is becoming a common practice in order to reduce pollutant emissions during cold start. In such applications, the exhaust gas mass flow may fluctuate, as a function of crankshaft angle. A simplified one-dimensional channel model is developed, assuming that pollutant conversion in the catalyst is mass transfer limited. This model is applied to evaluate the effect of pulsations in catalyst performance, and assess the accuracy of the “quasi-steady state” approach usually involved in three-way catalytic converter models, when applied to simulate converters under pulsating flow.
Design and Optimization of a Mechanism for Out-of-Plane Insect Winglike Motion With Twist
Authors: Banala Sai K. , Agrawal Sunil K.
Published: June 2005

A mechanism is presented that can generate insect winglike motion. This motion includes both flapping out of the stroke plane in addition to twist of the wing. The mechanism has a single degree of freedom and employs a five-bar mechanism in addition to an auxiliary four-bar mechanism. The parameters in the mechanism were optimized to generate a prescribed motion of the wing taken from a hawk moth kinematic flight data. A scaled model of the mechanism was fabricated to verify practical feasibility of the design. In future, we will miniaturize this mechanism on our flying-bird prototypes.
SEARCH AND IDENTIFICATION OF EXTRA SPATIAL DIMENSIONS AT LHC
Authors: DVERGSNES ERIK W. , OSLAND PER , PANKOV ALEXANDER A. , PAVER NELLO
Published: June 2005

We present an analysis, based on the center–edge asymmetry, to distinguish effects of extra dimensions within the Arkani-Hamed–Dimopoulos–Dvali (ADD) and Randall–Sundrum (RS) scenarios from other new physics effects in lepton-pair production at the CERN Large Hadron Collider LHC. Spin-2 and spin-1 exchange can be distinguished up to an ADD cutoff scale, MH, of about 5 TeV, at the 95% CL. In the RS scenario, spin-2 resonances can be identified in most of the favored parameter space.
2-COMPONENT INTEGRABLE COSMOLOGICAL MODELS
Authors: MELNIKOV V. N. , GAVRILOV V. R.
Published: June 2005

A large class of integrable cosmological models with two matter components is presented. The D-dimensional models on the space-time manifold [Formula: see text] are studied in the presence of 2 separately conserved barotropic perfect fluids. Such model are reducible to pseudo-Euclidean Toda-like system and integrable when their barotropic parameters satisfy some algebraic relations. Methods for integrating of pseudo-Euclidean Toda-like systems are based on the Minkowski-like geometry for characteristic vectors composed from the barotropic parameters. We also apply the methods for the spatially flat Friedmann-Robertson-Walker universe containing a perfect fluid and a minimally coupled self-interacting scalar field with a potential comprised of two exponentials.
BLACK HOLES AND WORMHOLES IN RS2 TYPE BRANE WORLDS
Authors: BRONNIKOV K. A. , MICHTCHENKO A. V.
Published: June 2005

We review some recent results concerning the properties of static, spherically symmetric configurations in RS2 type brane worlds: 1) Solving the trace of the effective 4D gravity equations, we obtain general classes of black hole and wormhole metrics, including families which unify symmetric wormholes, extremal black holes and non-extremal non-singular black holes. 2) Assuming [Formula: see text] (where [Formula: see text] is a part of the 5D Weyl tensor contributing to the 4D gravity equations), we show that material scalar fields confined on the brane may violate the no-hair theorem, support wormholes or form particlelike objects, but only at super-nuclear matter densities in the strong field region. 3) Solutions to the bulk field equations are found in case [Formula: see text], among them solutions with a nonzero 4D cosmological constant, generalizing the so-called "black string".
BLACK HOLES: OBSERVATIONAL PROPERTIES
Authors: ZAKHAROV A. F.
Published: June 2005

In the article we review observational features of black holes where an influence of a gravitational field is dominant and we must use strong gravitational field approach for GR. Recent X-ray observations of microquasars and Seyfert galaxies reveal broad emission lines in their spectra, which can arise in the innermost parts of accretion disks. Simulations indicate that at low inclination angle the line is measured by a distant observer as characteristic two-peak profile. However, at high inclination angles (> 85°) two additional peaks arise. This phenomenon was discovered by Matt et al. (1993) using the Schwarzschild black hole metric to analyze such an effect. They assumed that the effect is applicable to a Kerr metric far beyond the range of parameters that they exploited. We check and confirm their hypothesis about such a structure of the spectral line shape for the Kerr metric case. We discuss how analysis of the iron spectral line shapes could give an information about an upper limit of magnetic field near black hole horizon.
TRANSITION AND REGENERATION RATES IN CHARGED BOSON STARS VIA PERTURBATIVE CALCULATIONS
Authors: DARIESCU CIPRIAN , DARIESCU MARINA–AURA
Published: June 2005

In a SO(3,1)×U(1) framework, we analytically derive the first-order approximating solutions to the system of Klein–Gordon–Maxwell–Einstein equations describing a minimally coupled charged boson field to a spherically symmetric spacetime. Within a perturbative approach, we analyze the feedback of gravity and electric field on the charged scalar source and we get the coherent source-field regeneration rate. It turns out that we are dealing with an extremely short time-constant which is confirming the other authors' conclusion that intense gravitational bursts are accompanying the boson star formation.
IMPROVED ACTION FUNCTIONALS IN NON-PERTURBATIVE QUANTUM GRAVITY
Authors: BONANNO A. , ESPOSITO G. , RUBANO C.
Published: June 2005

Models of gravity with variable G and Λ have acquired greater relevance after the recent evidence in favour of the Einstein theory being non-perturbatively renormalizable in the Weinberg sense. The present paper builds a modified Arnowitt–Deser–Misner (ADM) action functional for such models which leads to a power-law growth of the scale factor for pure gravity and for a massless ϕ4 theory in a Universe with Robertson–Walker symmetry, in agreement with the recently developed fixed-point cosmology. Interestingly, the renormalization-group flow at the fixed point is found to be compatible with a Lagrangian description of the running quantities G and Λ.
STOCHASTIC GRAVITY AND THE LANGEVIN-RAYCHAUDHURI EQUATION
Authors: BORGMAN J. , FORD L. H.
Published: June 2005

We treat the gravitational effects of quantum stress tensor fluctuations. An operational approach is adopted in which these fluctuations produce fluctuations in the focusing of a bundle of geodesics. This can be calculated explicitly using the Raychaudhuri equation as a Langevin equation. The physical manifestation of these fluctuations are angular blurring and luminosity fluctuations of the images of distant sources.
CLASSICAL BLACK HOLE PRODUCTION IN QUANTUM PARTICLE COLLISIONS
Authors: RYCHKOV VYACHESLAV S.
Published: June 2005

A semiclassical picture of black hole production in trans-Planckian collisions is reviewed.
THE LOCAL SHAPE OF THE UNIVERSE IN THE INFLATIONARY LIMIT
Authors: MOTA B. , REBOUÇAS M. J. , TAVAKOL R.
Published: June 2005

Recent high precision data by WMAP and SDSS have provided strong evidence to suggest that the universe is nearly flat. They are also making it possible to probe the topology of the universe. Motivated by these results, we have recently studied the consequences of taking the inflationary limit, i.e. |Ω0 - 1| ≪ 0. We have shown that in this limit a generic detectable spherical or hyperbolic topology is locally indistinguishable from either [Formula: see text] or [Formula: see text], irrespective of its global shape. Here we briefly present these results and further discuss their observational implications.
MIRROR WORLD AND AXION: RELAXING COSMOLOGICAL BOUNDS
Authors: GIANNOTTI MAURIZIO
Published: June 2005

The cosmological (upper) limit on the Peccei-Quinn constant, related to the primordial oscillations of the axion field, can be relaxed for a mirror axion model. The simple reason is that the mirror world is colder and so the behavior of the axion temperature-dependent mass is dominated by the contribution from the mirror sector. So the coherent oscillations start earlier and correspondingly the axion mass density Ωah2 is reduced.