bluuebunny/crossref_metadata_2025 huggingface dataset:
Increasing Productivity Using Parametric Data and Macros
Authors: Gorman Robert W.
Published: April 2021

Computer-aided Engineering (CAE) has successfully helped engineers in the 1980’s to decrease the product development cycle. This has allowed companies to define high-quality, competitively priced products. In the 1990’s, companies must expand the role of CAE to help decrease the development cycle even more (i.e., increase the productivity of CAE). This paper will discuss two modeling techniques that can help designers/analysts initially define a computer model and automatically update this model when a component is altered. These techniques are the ability to define the model in terms of parametric data and to customize software packages to fit a company’s particular needs, by using macros. Designers who produce variations of a basic design or who model components geometrically based on other components will be able to increase their productivity using these techniques. Several examples will be used to illustrate how these techniques will increase productivity and how automatic design optimization may be used.
A Computer-Aided Environment for Analysis and Design of Mechanical Systems
Authors: Lankarani Hamid M. , Bahr Behnam , Motavalli Saeid
Published: April 2021

This paper presents the description of an ideal tool for analysis and design of complex multibody mechanical systems. It is in the form of a general-purpose computer program, which can be used for simulation of many different systems. The generality of this computer-integrated environment allows a wide range of applications with significant engineering importance. No matter how complicated the mechanical system under consideration is, a numerical multibody model of the system is constructed. The governing mixed differential/algebraic equations of motion are automatically formulated and numerically generated. State-of-the-art numerical techniques and computational methods are employed and developed which produce in the response of the system at discrete time junctures. Postprocessing of the results in the form of graphical images or real-time animations provides an enormous aid in visualizing motion of the system. The analysis package may be merged with an efficient design optimization algorithm. The developed integrated analysis/design system is a valuable tool for researchers, design engineers, and analysts of mechanical systems. This computer-integrated tool provides an important bridge between the classical decision making process by an engineer and the emerging technology of computers.
Compensation of Robot Joint Variables Using Special Jacobian Matrices
Authors: Mirman C. R. , Gupta K. C.
Published: April 2021

In dealing with an industrial manipulator, the end-effector accuracy is a major concern. The positioning of the end-effector is determined by the controller which utilizes the data from a closed-form kinematic inversion. The closed-form inversion uses nominal, i.e. manufacturer specified, values of link lengths, twists, and offsets. Due to manufacturing tolerances, set-up, and usage, these nominal parameters may be inaccurate. If the nominal parameters contain built-in error values, the closed-form kinematic inversion will yield incorrect joint values, and the actual end-effector position will deviate from its desired position.

One may use a parameter identification method to identify the position-independent error parameter values. This paper assumes that this has been done and it presents an Iterative Compensation Algorithm (ICA) through which the identified position-independent parameter error values may be used to correct the joint values which are obtained through the closed-form kinematic inversion. The Denavit and Hartenberg (D-H) parameters (θ s α a) are used to model the given M-jointed manipulator, and a set of four special Jacobian matrices (Jθ, Js, Jα, and Ja) are formulated. The iterative compensation algorithm allows one to determine the M unknown position-dependent joint error values, by using these four special Jacobian matrices. The improvements obtained through the use of the compensation algorithm will be presented for regular trajectories, as well as when the robot nears certain singularity conditions. Since it is important to know a priori a definite number of iterations which must be performed, the level of compensation after a fixed number of iterations is also studied. Through the presentation of numerous examples, it is shown that the proposed compensation algorithm is simple and straightforward to implement, and it increases the end-effector accuracy.
Variational Solid Modeling for Tolerance Analysis
Authors: Gupta Suvajit , Turner Joshua U.
Published: April 2021

Variational solid modeling is concerned with the development of solid models that allow for variation. In particular, this paper is motivated by the use of variational solid models for the analysis of design tolerances. Variations are applied to a part boundary model by independently varying each surface. This paper addresses the following significant problems: removal of excess sources of variation that produce rigid-body motion; handling of incidences and tangencies; and modeling of form variations. The application of these techniques to the solution of tolerancing problems is briefly discussed.
Non-Newtonian Flow Over a Wedge With Injection or Suction
Authors: Garg Vijay K.
Published: April 2021

A pseudo-similarity solution is obtained for the flow of an incompressible fluid of second grade past a wedge with suction or blowing at the surface. The non-linear differential equation is solved using quasi-linearization and orthonormalization. The numerical method developed for this purpose enables computation of the flow characteristics for any value of the parameters K, a, and b, where K is the dimensionless normal stress modulus of the fluid, a is related to the wedge angle, and b is the suction or blowing parameter. A significant effect of suction or blowing on the wall shear stress is observed. The present results match exactly with those from an earlier perturbation analysis for Kx2a ≤ 0.01 but differ significantly as Kx2a increases.
Prediction of Confined Coaxial Turbulent Jet Mixing With a Streamwise Differencing Scheme
Authors: Sharif M. A. R. , Gadalla M. A.
Published: April 2021

Isothermal turbulent mixing of an axisymmetric primary air jet with a low velocity annular secondary air stream inside a constant diameter cylindrical enclosure is predicted. The flow domain from the inlet to the fully developed downstream locations is considered. The predicted flow field properties include the mean velocity and pressure and the Reynolds stresses. Different velocity and diameter ratios between the primary and the secondary jets have been investigated to characterize the flow in terms of these parameters. A bounded stream-wise differencing scheme is used to minimize numerical diffusion and oscillation errors. Predictions are compared with available experimental data to back up numerical findings.
Computer Aided Optimal Design of Heat Exchanger Networks
Authors: Seshadri P. , Witte Larry C.
Published: April 2021

A method for finding the best (optimal) operating layout of heat exchangers in complicated thermal networks is developed in this paper. Computer algorithms are developed that take advantage of pinch technology and economic considerations, and exergetic constraints as well as conventional heat and mass balances. Our goals were to achieve minimum loss of exergy between hot and cold streams subject to practical system constraints. Furthermore, resulting networks should be limited to no more units than the theoretical minimum. The ultimate goal was to minimize investment and operating costs for a set of fixed overall system constaints.

These goals were realized by developing a computer-based nonlinear multiple objective optimization algorithm that included the elements discussed above. The final solution is a synthesis of the best system using the above-described mathematical formulation. Results for a 4-stream heat exchanger network are presented in terms of the minimum temperature difference at the pinch point. The influence of the minimum temperature difference on capital cost, heat transfer area, exergetic losses and second law efficiency of various heat exchangers in the network is presented.
Computer-Assisted Optimal Design of Energy Systems
Authors: El-Sayed Y. M. , Saad Michel A.
Published: April 2021

Numerical methods are used to model, predict and optimize energy systems in which thermodynamic analysis is coupled with design and economic evaluation. Two examples, in which the cost objective functions are assumed, are presented. The first example is a regenerative gas-turbine cycle in which several thermodynamic and design decision parameters are optimized for the given structure are considered. The second is a steam bottoming cycle, in which structural as well as parametric changes are introduced. Structural changes assume generating steam at several pressures and parametric changes assume different pressures, pinch and terminal temperature differences and different sets of pressure losses. The essential features of a software adequate for this type of analysis are described.
Flow Analysis Procedure for Steam Turbines
Authors: Kubiak A. , Luniewicz B. , del Angel F.
Published: April 2021

An algorithm (computational procedure) for flow analysis of steam turbines is presented. The algorithm is specially designed for analysis of low pressure turbines but is applicable in the same way for high pressure turbines. The analysis of the flow is carried out stage by stage (or row by row). The algorithm is so designed that a turbine of known geometry can be assessed with respect to its throughput (flow) and performance capabilities at arbitrary flow rates and steam conditions. The performance parameters include stage efficiency, rotor blade loading, blade section efficiency, and all aero/thermodynamic parameters within the blade path. On the other hand the algorithm can be used for turbine design purposes. The algorithm deals with 2D flow.

The analysis starts from the last stage and proceeds up-stream. There are several iteration loops where the mass flow is computed and compared to a required value. The algorithm is capable of determining stage flow given the stage pressure and vice versa. The algorithm can be expanded to assimilate new capabilities (for example: radial equilibrium applied to rotor). The algorithm can be applied especially for upgrading the turbines of older design.
Design and Heat Integration of a Power Plant Using Multi-Objective Optimization
Authors: Seshadri P. , Witte Larry C.
Published: April 2021

A heat integration technique for designing a Rankine cycle power plant that is based on modelling the cycle as a multi-objective optimization problem is presented in this paper. The heat integration procedure uses the same scheme that is used in designing complex heat exchanger networks. The hot and cold streams are identified and the pinch point is determined along with minimum heating and cooling targets. An initial configuration is designed and a multi-objective nonlinear optimization formulation of the initial configuration is solved to obtain the best feedwater heater bleed rates The procedure is based on a Rankine cycle thermodynamic simulation, program, along with exergy accounting and other applications of heat integration techniques.

The best solution values of the power plant variables have been determined for a typical Rankine cycle base plant by solving a compromise decision support problem (DSP) with a solver called DSIDES. Variation of thermal and exergetic efficiency of the power plant with feedwater heater flow rates was investigated. The heat integration of the power plant based on pinch technology for the heat recovery streams showed that fuel savings up to 1% are achievable. When translated to dollars saved, these are sigificant for large power stations.
Thermal Characteristics of Kickless Welding Cables Using Finite Element Analysis
Authors: Heist James , Berry K. J.
Published: April 2021

A new welding cable prototype, similar to a design by Watteredge-Uniflex Inc., contains six 30 AWG braided copper strands. The strands are of herringbone rope construction and have a non-conductive EPDM rubber star separator to maintain strand positioning and to equally distribute cooling water through the cable. The cable has a low inductive reactance to minimize operating temperatures and wear.

Transient and steady state heat transfer was analyzed in a prototype cable using Finite Element Analysis (FEA) combined with Computer Aided Drafting (CAD). The analysis numerically determined catastrophic failure times after sudden loss of coolant and developed a computer simulation model for future parametric studies. The FEA model is generated with eight node quadrilateral elements, and the analysis includes internal heat generation rates due to temperature dependent resistance in the copper strands. The FEA results are presented with a discussion of the mesh generation and analysis software.
Numerical Simulation of Supersonic Combustion in Quasi One-Dimensional Flow
Authors: Yip T. Gary
Published: April 2021

Supersonic combustion induced by a two-shock system has been studied using a chemical nonequilibrium, quasi one-dimensional flow model. The combustion of stoichiometric, premixed H2-air is described by a chemistry model which consists of 11 species and 28 reactions.

The freestream Mach numbers used in this calculations are 8, 10 and 12. The initial pressure is 0.01 atm and temperature 300 K. The first of the two shocks is a conical shock and the second is its reflection. Supersonic combustion has been predicted to occur at combustor pressures between 0.8 and 2.9 atmospheres, and temperatures between 1500 and 3000 K. The Mach number of the flow in the combustor is between 1.7 and 4. These combustor conditions are typical of the future hypersonic propulsion systems. The results also show the changes in the composition of the flow during the induction and heat release phases.

The two-shock system is assumed to be generated by a cone. For Mach 8, 10 and 12, the minimum cone angle for generating a strong enough two-shock system to induce supersonic combustion has also been identified.
Computerized Reconstruction of Building Fires
Authors: Lilley David G.
Published: April 2021

A fire development simulation model is described which provides estimates of the amount and temperature of the smoke layer produced, the evolution of toxic gases, and the amount of time available from the onset of fire for the safe departure of occupants. Its results can be used to determine the key features of the fire evolution and the corresponding danger to occupants. Studies of this type help to validate or deny the suggested fire scenario and witness statements. Mathematical modeling thus helps to discriminate between alternative fire scenarios by evaluating the consequences and comparing them with observations.

The software consists of data, procedures, and computer programs which simulate important time-dependent phenomena involved in residential fires. Based on sound scientific and mathematical principles, predictions are made of the production of energy and mass (smoke and gases) by one or more burning objects in one room, based on small or large scale measurements. The buoyancy-driven transport of this energy and mass through a series of user-specified rooms and connections is then computed (doors, windows, cracks, etc.). The resulting temperatures, smoke optical densities, and gas concentrations (after accounting for heat transfer to surfaces and dilution by mixing with clean air) are linked to the problem of egress. The evacuation process of a set of occupants may be simulated, accounting for delays in notification, decision making, behavioral interactions, and inherent capabilities.
The Use of Advanced Transient Structural Codes to Study Interior Gun Dynamics
Authors: Wilkerson Stephen
Published: April 2021

Three-dimensional numerical models used to analyze the in-bore dynamics of kinetic energy projectiles are presented. The intricate modeling process, boundary conditions, and assumptions used in the analysis are given. Numerical results are analyzed and presented to show the importance of three-dimensional numerical studies. Finally possible areas of concern and future improvements in the numerical techniques used are reviewed.
Evaluation of Civilian Blast Damage Claims
Authors: Bulmash Gerald
Published: April 2021

US Army military installation activities include firing guns and detonation of explosives generating blast waves which propagate to neighboring communities and cause complaints of damage. This brief paper discusses some aspects of claim processing and explains damage assessment methods.
A Two-Level Multigrid Algorithm for Solving 3-D Quadratic Finite Element Models
Authors: Pressburger Yoram , Perucchio Renato , Field David A.
Published: April 2021

A two-level multigrid algorithm for solving a quadratic finite element models containing tetrahedral meshes is presented. The basic idea is to generate two nested finite element models, first a linear model and then a quadratic one embedded hierarchically into the linear one. The exact solution to the linear model is computed and a two-level iterative procedure is used to solve for the quadratic model. In particular, the Successive Over Relaxation (SOR) method is used for the smoothing iteration on the quadratic model in each two-level cycle. A numerical study is carried out to determine how the relaxation factor and the number of SOR iteration in each two-level cycle influence the convergence rate of the complete algorithm. The stopping criterion for the iteration is based on the notion that the error in the iterative procedure will be of the same order as the error in the finite element approximation. Finally, the efficiency of the algorithm is evaluated by comparing the computational time with that of an exact solver based on Gauss elimination. Results indicate that the present algorithm produces substantial saving of CPU time.
An Element Error Indicator for Guided Adaptivity With the p-Version
Authors: Schiermeier John E.
Published: April 2021

In this paper, the background of the p-version and the calculation of the p-version element error indicator will be discussed. The application and performance of the indicator will be demonstrated through examples. The utility of the indicator for guided adaptivity will also be demonstrated through examples with variable polynomial level.
Analytical Evaluation of the Integrals Appearing in the Boundary Element Method for Some Problems in Mechanics
Authors: Bora Jugma N.
Published: April 2021

The boundary integral equation method or simply the Boundary Element Method (BEM) is now considered to be a powerful tool for solving problems in mechanics. A large number of the line and area integrals appearing for two-dimensional problems, in the BEM, can be represented as linear combinations of four singular functions. These integrals that are generated are products of the approximating polynomials and one or more of the four singular functions. These integrals can be evaluated numerically or analytically. The advantage of numerical integration is that the shape of the boundary can be of any complexity. The big disadvantage is that another source of error, besides the polynomial interpolation, is added into the process due to the approximation of the integrand for numerical integration. The singular nature of the fundamental solutions further exacerbates this disadvantage. In analytical integration, the form of the boundary must be assumed. The usual representation is a sum of straight-line segments. Currently, analytical expressions are available only for a few formulations and they are valid only for zero- and first-order polynomials. In this paper analytical expressions of the integrals are obtained for approximating polynomials of any arbitrary order. The fundamental solutions of the Laplace, Biharmonic and the equation of Plane Elastostatics are considered. The validity and advantage of using these integrals are shown by some simple problems in mechanics that have theoretical solutions.
Self-Adaptive Algorithm for Efficient Computation of Elasto-Plastic Material Process
Authors: Lee Sang H.
Published: April 2021

Due to the path-dependent nature of the plastic material, plastic strains are calculated by an incremental procedure and the total strains are obtained by summation in the numerical computation. MSC/NASTRAN employs an adaptive subincremental process at the Gauss point level for accuracy and efficiency. Various options for yield criteria and hardening rules are implemented. The generalized effective plastic strain increment is derived to accommodate various yield criteria. By virtue of some salient considerations in implementing the numerical procedure, difficulties associated with unloading have been resolved. This paper focuses on the adaptive features which allowed efficient computations of elasto-plastic material processes commonly comprising unloading, reloading and nonproportional loading. Select examples show novel applications of the elasto-plastic material capabilities.
A Simple and Efficient Large-Displacement Formulation for Beam Elements
Authors: Tang Xiaodong
Published: April 2021

A simple and effective finite element formulation of beam-column stiffness matrix with the consideration of second-order displacement is presented. The derived second-order stiffness matrix is the simple addition of the small-displacement stiffness matrix and a few other component matrices. The matrix is derived closed form and no integration is necessary during the formation of the element stiffness matrix. The simple additive relation makes it easy to understand the composition of the second-order stiffness matrix and the meaning of each component matrix. The closed-form formulation eliminates the potential numerical error and considerably reduces the amount of computation thereby, increasing the computing speed. The standard finite element approach presented in this paper makes the beam-column compatible with other finite elements and can be incorporated into existing finite element programs with little modification. The analysis of a simply supported beam with axial restraints using the beam-column element shows a good correlation with the test results.
GRAPE: Finite Element Analysis and Shareware
Authors: Luczak E. R. , Letan Q.
Published: April 2021

Use of Finite Element Methods are becoming more prevalent as we move into the 1990’s. More engineers and engineering technologists than ever before are graduating from universities and colleges with knowledge and expertise in the method. A wide assortment of programs are now available that run on micro’s, mini’s, mainframes, and super computers with a broad spectrum of capabilities and costs. Enter the Shareware concept. Shareware does not mean free software. It does mean that software may be freely distributed to promote it’s use and therefore is available to the user at very low cost. This paper discusses a highly interactive Finite Element Analysis system specifically suited for engineers and technologists. GRAPE (Graphic Real-Time Analysis Programs for Engineering) is a series of Shareware programs created to provide the tools necessary to obtain an applied understanding of the technique. GRAPE allows an easy transition to the usage of more complex and powerful codes. A number of sample models are created and analyzed using one of the GRAPE programs, called GCST, to illustrate the ease with which real world applications can be modeled and studied. It is GRAPE’s responsive interactive approach that allows the user to quickly modify the condition of a model and thus note the effects that makes the study of the method appealing and unique. Most experienced users will agree that knowledge of a software package is necessary but the important aspect of being proficient in the method is the synthesis of how to properly model a problem. GRAPE allows the engineer to solve problems easily and quickly to obtain this desired level of competence.
Approximate Solution of Nonclassically Damped Systems
Authors: Ma F. , Hwang J. H.
Published: April 2021

In analyzing a nonclassically damped linear system, one common procedure is to neglect those damping terms which are nonclassical, and retain the classical ones. This approach is termed the method of approximate decoupling. For large-scale systems, the computational effort at adopting approximate decoupling is at least an order of magnitude smaller than the method of complex modes. In this paper, the error introduced by approximate decoupling is evaluated. A tight error bound, which can be computed with relative ease, is given for this method of approximate solution. The role that modal coupling plays in the control of error is clarified. If the normalized damping matrix is strongly diagonally dominant, it is shown that adequate frequency separation is not necessary to ensure small errors.
Precision Machines: Diagnostics of Vibration Through Modal and Finite Element Analysis
Authors: Prakash V. , Montague R. J.
Published: April 2021

This paper presents the diagnostics of the effects of vibration on the precise placement of electronic components in a surface mount assembly process. Experimental Modal Analysis using present day software/hardware as well as a three dimensional finite element model are performed on the machine structure. Correlation between the experiment and finite element model are also performed and the strength of using the finite element model as a test model for contemplating any design alterations are presented.
Finite Element Mesh Generation With Computed Tomography Scan Data
Authors: Wei C. Stan , Skinner Clark D.
Published: April 2021

This report presents a new finite element meshing approach, put forth by Q-Mesh, to producing 3-D mesh models for solid objects whose geometries can be captured with an industrial computed tomography (CT) scanner.

The Q-Mesh system utilizes a series of deformable grid templates and component solid regions to create a 3-D global mesh that can be divided into subregions of connected meshes located within the component solids. It provides an interactive graphics interface through which the user can design and visualize 3-D, multiregion meshes consisting of well-formed wedge and hexahedron elements.

The unique solid-modeling algorithm implemented in Q-Mesh allows the system to generate, automatically, matching finite element meshes across any number of solid regions. This unique feature makes Q-Mesh an ideal mesh generator for finite element solvers geared to the simulation of general multiregion problems. Furthermore, the use of a multiregion mesh model as the source for analysis models representing variations of a single-region mesh, as unions of selected subregions, has proven more time efficient and cost effective than the single-region alternative where each variational model has to be regenerated from scratch.

This report focuses on the utility of a CT scanner as a geometry input processor to Q-Mesh. The generation of finite element models for a solid object represented in the form of sliced CT scan data involves two phases: (1) converting the sliced CT scan data into a series of stacked solids; and (2) utilizing Q-Mesh’s interactive design tools to build mesh models based on the reconstructed solids. A number of examples are given to demonstrate the general procedure and unique capabilities of the new meshing approach.
Teaching Advanced CAD Concepts
Authors: Tombers Paul A.
Published: April 2021

The purpose of this paper is to share my experiences with my fellow engineers and educators involved in teaching advanced CAD courses. Advanced CAD in the context of this paper simply means teaching topics that are not usually covered in an introductory CAD course.

Appropriate advanced CAD topics can be categorized into two major areas; using the advanced features of the CAD software and customizing the CAD system to meet individual needs. The advanced features of the CAD software presented in this paper will include the use of attributes and the creation of three-dimensional models. Customizing the CAD system will be accomplished by modifying various existing system files and writing macro programs that accomplish specific tasks for the CAD user.

The paper presents detailed explanations of the above mentioned topics, assignments that can be used in the classroom and in the CAD laboratory, and a sample course outline.
A Work Cell Animator for Robotics Instruction
Authors: Toogood R. W.
Published: April 2021

For introductory robotics courses with high student/robot ratios, the lack of robotic hardware can be a problem in providing adequate hands-on experience with robot programming. Used in place of actual robots, computer animation can provide an acceptable substitute to gain insight into robot kinematics and programming. As well, the animation can be used to verify robot programs developed off-line as to movement sequence, illegal moves, and obstacle avoidance. This paper presents a detailed analysis of an algorithm used in a microcomputer animation of a robot moving in a work cell. Topics discussed include representation of the robot and objects in the work cell, specification of the view frame, perspective projection, and several techniques for producing the animation.
The Development of a Generally Applicable Digital Computer Spokes Tyre Model
Authors: El-Nashar M. , Watany M.
Published: April 2021

An extensive survey is presented for the analysis of both in-plane and out-of-plane pneumatic tyre models. The single plane tyre model[2,9] is developed to represent the influence of tyre width by using many conical shell shapes built from spokes with different head angles. The general form of the new tyre model is based on the well-known single plane steady state version of the tyre model. The mathematical analysis and geometrical form of the developed model is given.

A computer program is designed for desk top P.C. without costly running times which makes it useful for representing the pneumatic tyre/road contact forces. Model assumptions and parameters were chosen to give qualitative and quantitative agreements between theoretical and experimental results.

The paper also presents an experimental study for investigating the influence of working conditions on tyre/road contact forces. The experimental results were carried out using the steady state tyre testing machine constructed in the Automotive Engineering Department, Helwan University [3,10]. Experimental findings for 145 SR 13 tyres are compared with the new model theoretical results. Experiments on real tyres show good agreement with the predicted theoretical results of the new generally applicable model.
On-Line Food Processing Robotics: A First Step
Authors: Thompson J. C. , Holcombe W. D. , McMurray G. V. , Wyvill J. C.
Published: April 2021

Food processors today are facing a number of challenges that increasingly make the application of robotics both attractive financially and necessary for their survival. These challenges include foreign competition, a dwindling workforce, increasing safety regulation, demands for increased throughput, and a growing concern for quality improvement to name a few. To date however, robotics have not been successfully employed in this industry due to a number of significant technical shortcomings including speed, end-effector adaptability, environmental ruggedness, and cost. This paper describes two prototype robotic workcells designed for the poultry industry. One cell handles packaged product while a second manipulates raw chicken for cut-up. The challenges involved are described in detail as well as the preliminary results of initial designs and trial operation. From this research a number of focus areas have been identified for future research. Future plans include the development of smart sensor equipped end-effectors, visual guidance systems, force feedback control, and truly universal gripper designs.
Precision Positioning With Force Sensing and Fuzzy Control
Authors: Gürocak H. , de Sam Lazaro A.
Published: April 2021

The use of force feed back for manipulator control is a well established technique. However, measurement inaccuracies and system noise precluded any practical deployment of this method. In this paper an approach to force sensing and measurement will be discussed. A method of accounting for measurement errors and system noise will be introduced. The use of fuzzy control for fine positioning will be presented. The method described in this paper provides an inexpensive alternative to vision systems using a software approach.
A Spherical Hierarchical Representation for Robot Motion Planning
Authors: Pasqual del Pobil Angel , Serna Miguel A.
Published: April 2021

A simple and practical model with applications in 3D motion planning is presented. The new model is based on a double spherical hierarchy of detail to represent solid bodies.

First, each element making up the robot and the obstacles is approximated by means of a set of exterior spheres which are automatically defined. Second, another set composed of interior spheres is generated. These representations define a hierarchy, since they can be redefined as many times as necessary: starting with two spheres per element, the approximation may be improved until it contains hundreds of spheres. Moreover, they converge to a zero-error representation.

The proposed spherical model leads to a simple treatment for the problem of dynamic collision detection, and it is further applied to collision-free path planning for robot manipulators in 3D.
Precise Vision-Based Tracking of an Autonomous Floor-Maintenance Vehicle
Authors: Baumgartner E. T. , Skaar S. B. , Strebinger R. B.
Published: April 2021

This paper describes a unique approach to the estimation and control of the trajectory of an autonomous floor-maintenance vehicle. Several requirements and challenges attend the floor-maintenance objective which are shown experimentally to be addressed using our new formulation. The procedure involves a combination of visual sensing, internal wheel rotation sensing, extended Kalman filtering, and teach/control operation.
Steady State Optimal Control Approach for Aluminum Turning
Authors: Suliman S. M. A. , Hassan G. A.
Published: April 2021

A steady state control algorithm has been developed. The algorithm is based on steady state process models established and used to provide algebraic control model. The control model can be applied for on-line computation of new levels of the aluminium turning process control variables required to compensate for the detected errors of process controlled variables. Workability of the developed control algorithm and its performance are evaluated by computer simulation. Although the control methodology is developed for aluminium turning process, it is general and can be applied to any machining process.
Design and Implementation of Self-Tuning Regulators for Active Noise Control
Authors: Shoureshi Rahmat , Matsuyoshi Yasuhiro
Published: April 2021

Acoustic noise has become an increasingly important problem, especially in industrial societies. The main reason being the increase in usage of machines in virtually all aspects of our lives, higher population densities, and concerns about the health consequences of exposure to acoustic noise. Passive noise control methods work well for relatively high frequency noise, but become progressively more expensive and less effective as one considers control of lower frequency noise. Development and implementation of an adaptive active noise controller is presented.
Automated Hybrid Analysis of Surface Mounted Electronic Assemblies
Authors: Wong Tin-Lup , Wang Junshi , Stevens Karl K.
Published: April 2021

Simulations of surface mounted electronic assemblies under general mechanical loading conditions have been performed using an hybrid analytical/experimental analysis approach. This method combines analytical techniques with experimentally determined load-deformation characteristics of the surface-mounted assemblies to predict loadings and deformations of the assemblies. An automated analysis procedure which integrated the finite element method, optimization theory and the hybrid analysis approach was developed. This procedure can be used to study the strength of the surface mounted devices located anywhere on a printed circuit board subjected to the specified loading conditions.
Automatic Dimensioning From 3D Solid Model With Feature Extraction
Authors: Oh Je Hwan , Lee Kunwoo
Published: April 2021

A scheme for automatic dimensioning of a part created by B-rep based modeling system is presented. Since size dimensions and location dimensions are required for defining part features in engineering drawings, part features are extracted first from a B-rep model for the automatic dimensioning.

Faces which constitute a feature are found in two steps: the first by the edge-initiated approach and the second by the boundary-initiated approach. The recognized features are stored in a graph whose nodes are feature faces and edges represent their connections.

Once all the features are recognized, a linked list of identification points, called a dimension link, is generated automatically for each direction of dimensioning the part. Then, size and location dimensions of the part features are directly created from the dimension link and placed on the most descriptive view.
Tool Approach Directions for Machining Protrusion and Depression Features in an Object
Authors: Karra Chandrasekhar , Phelps Thomas A.
Published: April 2021

The success of any industry in today’s highly competitive market is largely dependent on its ability to produce quality products, quickly and at low cost. Evaluating the effect of a product design on its manufacture is crucial in developing efficient designs. Any potential manufacturing problems detected at this stage can be corrected by modifying the design, leading to shorter product development cycles and lower production costs. This paper presents an algorithm to determine feasible tool approach directions. The algorithm is based on detecting if any part of the object obstructs the tool path. The basis for the algorithm is determining feasible approach directions and clearances around a planar polygonal face. The algorithm is applicable to both protrusions and depressions. The information is useful in performing manufacturability analysis of designs and develop process plans.
Automatic Prototyping of Complex Geometries for Conceptual Design
Authors: Vergeest J. S. M. , Broek J. J. , Tangelder J. W. H.
Published: April 2021

The significance of materialized prototypes from CAD generated mechanical parts has been recognized since more than a decade. Despite the ever increasing quality and speed of graphical visualization methods, solid 3D hard copies from designs remain essential for certain stages in the creation process. Especially during the phase of conceptual geometric design, when alternative shape proposals must be quickly judged, automatic, fast and inexpensive production of replica is of importance. However, for such a kind of prototyping in conjunction with CAD, traditional methods based on CAM and NC technology turn out not adequate. To support conceptual design, several extensions and optimizations, mainly in the software area, need to be effected. In this paper an autonomous NC-milling process generator TLCOR is presented. It evaluates and analyzes surface/solid models based on NURBS, determines the physical constraints of the 3D milling devices (represented in a technical database) and finally produces an ISO-standard control statement sequence. The system selects the appropriate machining method (parametric and/or geometric algorithms) and tools, and breaks up the process into different stages of non-planar path planning with interference avoidance. The user will never be confronted with any aspect concerning the NC. The designer only needs to express his or her wish to obtain a milled copy of the actual CAD model. Extension of TLCOR to shape models defined neutrally (STEP/PDES based) and to multi-axis and robot milling is in progress.
The M-Space Theory of Tolerances
Authors: Turner Joshua U. , Wozny Michael J.
Published: April 2021

A rigorous mathematical theory of tolerances is an important step toward the automated solution of tolerancing problems. This paper develops a mathematical theory of tolerances in which tolerance specifications are interpreted as constraints on a normed vector space of model variations (M-space). This M-space provides concise representations for both dimensional and geometric tolerances, without deviating from the established tolerancing standards. This paper extends the authors’ previous work to include examples of geometric orientation and form tolerances. We show that the M-space theory supports the development of effective algorithms for the solution of tolerancing problems. Through the use of solid modeling technology, it is possible to automate the solution of such problems.
Generation and Modification of Non-Uniform B-Spline Surface Approximations to PDE Surfaces Using the Finite Element Method
Authors: Brown Joanna M. , Bloor Malcolm I. G. , Bloor M. Susan , Wilson Michael J.
Published: April 2021

A PDE surface is generated by solving partial differential equations subject to boundary conditions. To obtain an approximation of the PDE surface in the form of a B-spline surface the finite element method, with the basis formed from B-spline basis functions, can be used to solve the equations. The procedure is simplest when uniform B-splines are used, but it is also feasible, and in some cases desirable, to use non-uniform B-splines. It will also be shown that it is possible, if required, to modify the non-uniform B-spline approximation in a variety of ways, using the properties of B-spline surfaces.
QUINT: A Problem-Solving Strategy for Mechanical System Conceptual Design: Part I — Environment, Function, Structure, and Parameter
Authors: Qun Wang , Haibin Yang , Ji Zhou , Jun Yu
Published: April 2021

Mechanical system conceptual design, sometimes termed mechanical system scheme design or preliminary mechanical system design, is the key link of mechanical system design, and also the bottleneck of integrated CAD / CAM [1][2][3]. Therefore, it is important to automize this part of work to promote the quality of mechanical system design and the extent of product design automation.

This paper will discuss in detail a problem-solving strategy for mechanical system conceptual design — QUINT. It devides the conceptual design into five stages: (1) environment ▸ function; (2) function ▸ structure; (3) structure ▸ parameters; (4) parameters ▸ analysis; (5) analysis ▸ evaluation and decision. QUINT has already been successfully applied in CDESTOOL (Conceptual Design Expert System TOOL). With this tool, three practical systems have been developed: industrial turbine general scheme design expert system (TDES), wheel loader general scheme design expert system (WLDES), and milling-boring machining center scheme design expert system (MDES). The result is fairly satisfactory.
An Active Suspension Strategy Using State Reconstruction
Authors: Warner P. K. , Vanderploeg M. J. , Shannan J. E.
Published: April 2021

Many studies have shown that active suspensions using full state feedback can significantly improve the ride performance of ground vehicles. Using a seven degree of freedom vehicle model and a Kalman filter, this paper investigates the effects of reduced state feedback on active and semi-active suspension systems. Particular attention is given to control of pitch motion, which is usually considered to be the most uncomfortable of rigid body motions. The effects of phase differences between the tires is presented using frequency response surfaces.

The Kalman filter, which reconstructs the state variables from a reduced set of observed variables, yields improvements in ride which compare well with the ideal active suspension without the need to measure all states. The Kalman filter system with active dampers instead of ideal actuators also yields ride improvements approaching the ideal systems.
Optimal Packaging of Complex Parametric Solids According to Mass Property Criteria
Authors: Landon Mark D. , Balling Richard J.
Published: April 2021

A solution to the 3-D optimal packaging problem is presented. The positions and orientations of arbitrarily shaped objects in arbitrarily shaped 3-D containers are found. Mass property and spatial criteria are addressed. The robustness and speed of the optimal packaging solution is increased by supplying explicit gradients for the optimization search routines.
Experimental Validation of a Dynamic Simulation
Authors: Yae K. Harold , Chern Su-Tai , Hwang Howyoung
Published: April 2021

Using forward and inverse dynamic analysis, the dynamic simulation of a backhoe has been compared with experiments. In the experiment, recorded were the configuration and force histories; that is, velocity and position, and force output from the hydraulic cylinder-all were measured in the time domain. When the experimental force history is used as driving force in the simulation, forward dynamic analysis produces a corresponding motion history. And when the experimental motion history is used as if a prescribed trajectory, inverse dynamic analysis generates a corresponding force history. Therefore, these two sets of motion and force histories — one set from experiment, and the other from the simulation that is driven forward and backward with the experimental data — are compared in the time domain. The comparisons are discussed in regard to the effects of variations in initial conditions, friction, and viscous damping.
A Cross-Sectional Shape Multiplier Method for Two-Level Optimum Design of Frames
Authors: Zhao Wenzhong , Azarm Shapour
Published: April 2021

In this paper, a new method for optimum design of frame structures is presented. The method is based on a hierarchical decomposition of the structure into two-levels, namely, the bottom- and the top-level. The bottom-level consists of several subproblems each dealing with the cross-sectional sizing of a given frame-element. The top-level consists of one subproblem which is formulated for configuration design of the frame structure. Since there may be a large number of frame elements, a new shape multiplier method has been developed to simplify the formulation of the bottom-level subproblems. Furthermore, a two-level solution procedure has been developed which first solves the bottom-level subproblems based on their monotonicity analysis. It then solves the top-level subproblem as it coordinates, based on a linear approximation, the solutions to the bottom-level subproblems. Three examples with increasing degree of difficulty are presented to demonstrate the effectiveness of the method.
Shape Synthesis and Optimization Using Intrinsic Geometry
Authors: Tavakkoli Shahriar , Dhande Sanjay G.
Published: April 2021

The present paper outlines a method of shape synthesis using intrinsic geometry to be used for two-dimensional shape optimization problems. It is observed that the shape of a curve can be defined in terms of intrinsic parameters such as the curvature as a function of the arc length. The method of shape synthesis, proposed here, consists of selecting a shape model, defining a set of shape design variables and then evaluating Cartesian coordinates of a curve. A shape model is conceived as a set of continuous piecewise linear segments of the curvature; each segment defined as a function of the arc length. The shape design variables are the values of curvature and/or arc lengths at some of the end-points of the linear segments. The proposed method of shape synthesis and optimization is general in nature. It has been shown how the proposed method can be used to find the optimal shape of a planar Variable Geometry Truss (VGT) manipulator for a pre-specified position and orientation of the end-effector. In conclusion, it can be said that the proposed approach requires fewer design variables as compared to the methods where shape is represented using spline-like functions.