bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of simulation on cognitive load in health care professionals and students: protocol for a systematic review and meta-analysis
Authors: Lapierre Alexandra , Arbour Caroline , Maheu-Cadotte Marc-André , Radermaker Mélanie , Fontaine Guillaume , Lavoie Patrick
Published: March 2021

Objective:

The objective of this review is to assess the effect of simulation activities and their design features on cognitive load in health care professionals and students.

Introduction:

Simulation activities are now widely implemented in health care professionals’ education. However, the mechanisms by which simulations and their design features lead to health care professionals’ and students’ learning remains unclear. Still, because of their high interactivity and complexity, simulation activities have the potential to impact the cognitive load of learners. Synthesizing evidence regarding this phenomenon could help simulation educators identify the design features that affect learners’ cognitive load, and explain why some simulation activities are more effective than others.

Inclusion criteria:

This review will consider experimental and quasi-experimental studies in which the effect of a simulation activity on cognitive load in health care professionals or students from any discipline or level of practice is evaluated. All academic and health settings will be included.

Methods:

Following the guidelines of the JBI methods for systematic reviews of effectiveness, CINAHL, Embase, ERIC, MEDLINE, PsycINFO, and Web of Science will be searched for studies published in English or French, without a date limit. Retrieved studies will be independently screened for inclusion, then critically appraised for methodological quality by two reviewers using standardized JBI tools. Data extraction will be done independently using adapted tools from JBI. Where possible, data will be pooled using meta-analytical methods.

Systematic review registration number:

PROSPERO CRD42020187723
Measurement of physical activity in children and adolescents with cerebral palsy: a scoping review protocol
Authors: Johansen Mette , Rasmussen Helle M. , Lauruschkus Katarina , Laugesen Britt
Published: March 2021

Objective:

The objective of this scoping review is to identify and map subjective instruments that have been developed for children and adolescents with cerebral palsy from birth to 18 years to measure physical activity and sedentary behavior.

Introduction:

Children and adolescents with cerebral palsy often do not meet the recommended levels of physical activity, even though regular physical activity is an important determinant of good health. Considering the importance of physical activity, there is a need for systematic collection of data on daily activity and sedentary behavior of children and adolescents with cerebral palsy. Subjective instruments with clinical utility for use in quality registers are needed to evaluate interventions and investigate the relationship between activity and health outcomes.

Inclusion criteria:

This review will consider studies that include children and adolescents from birth to 18 years with cerebral palsy across levels I to V of the Gross Motor Function Classification System. Specifically, this scoping review will report on subjective instruments used to measure physical activity and sedentary behavior and that distinguish between physical activity performance and physical activity capability.

Methods:

This scoping review will be conducted in accordance with the JBI methodology for scoping reviews and will search the following databases: MEDLINE, CINAHL, Web of Science, Cochrane Database of Systematic Reviews, JBI Evidence Synthesis, Embase, and PEDro, as well as specific journals relating to physical activity assessment.
Infrared Temperature Measurements of the Blade Tip for a Turbine Operating at Corrected Engine Conditions
Authors: Christensen Louis , Celestina Richard , Sperling Spencer , Mathison Randall , Aksoy Hakan , Liu Jong
Published: March 2021

A high-speed infrared camera is used to measure the temperature of blade tips in a cooled high-pressure turbine operating at corrected engine conditions in The Ohio State University short duration Turbine Test Facility. These experiments create a challenging problem for infrared imaging since the rotor turns at over 13,000 rpm with tip speeds on the order of 300 m/s, and the surface temperature of the airfoils is on the order of 350 K. This means that the camera needs to capture a low-intensity signal in a very short time period. This article reviews the design and operation of a measurement procedure to accomplish this difficult task along with the postprocessing steps necessary to extract useful data. Raw infrared images are processed by deblurring the images using a nonblind Wiener filter and mapping the two-dimensional data onto the three-dimensional blade. This article also describes experiments covering a range of cooling flowrates and main flow temperatures. In addition, several tests with no main flow and only cooling flow were performed at lower speeds to reduce motion blur and enable the separation of internal and external heat transfer information. Results show that the infrared data are consistent and can provide quantitative comparisons of cooling performance even at the high rotation speed. This article presents the lessons learned for high-speed infrared measurement along with the representative data to illustrate the repeatability and capability of the measurement scheme as well as suggested improvements to guide further development.
An Approach to Represent Imprecision in Interactive Design Using Fuzzy Set Theory
Authors: Iqbal Numan , Kinzel Gary L.
Published: March 2021

Imprecision in the values of design parameters is an inherent character of the analysis stage of engineering design when the ideas have not yet converted to precise values and some of the design parameters remain flexible. The goal of this paper is to illustrate the application of the concepts of fuzzy set theory to represent this imprecision in design after a basic analytical model of the part being evaluated is developed. The idea is to help the designer efficiently study the effect of changing the values of certain parameters so that the number of iterations required to reach a final design can be reduced. The concepts of fuzzy set theory are used to represent design variables and the vertex method is utilized to calculate the fuzzy outputs in an interactive manner through an existing constraint manager (Design Shell) developed at The Ohio State University.
Features and Algorithms for Tooling Cost Evaluation in Injection Molding and Die Casting
Authors: Rosen David W. , Dixon John R. , Poli Corrado , Dong Xin
Published: March 2021

Design-for-manufacturability tools for thin-walled mechanical components are being developed and integrated into a feature-based design system. This paper presents recent work on automatically evaluating injection molded and die cast components for tooling cost. The methodology for evaluation is to convert a design features representation of a component into a tooling cost features representation, then compute cost drivers from the features. Evaluation can be done directly from the cost drivers using cost data in tables. The critical tooling cost features were derived from tooling cost drivers reported in previous work. The tooling cost features and cost drivers are listed, and definitions and algorithms for conversion from design-with to tooling cost features are given. At the end, conclusions are drawn on the feasibility of feature conversion and feature-based tooling cost evaluation, based on the design-with features approach.
A Framework for Sheet Metal Part Design and Manufacturing Assessment
Authors: Yu Tung-Ting , Chen Yuh-Min , Miller R. Allen , Kinzel Gary L. , Altan Taylan
Published: March 2021

In this paper, the framework for a sheet metal part design and manufacturing assessment environment is presented. Based on an investigation of the characteristics of sheet metal part design, form feature methodology is employed to facilitate design and provide information for assessment. The tasks, rules, and the significant items for manufacturing assessment are identified and formalized into a knowledge base with object-oriented techniques. The knowledge base is used for design assessment including evaluation for compatibility with press-working processes, modification of preliminary designs into better ones given cost considerations, and evaluation to avoid defects and failures. To support on-line design evaluations, a part model is constructed by extracting the required feature and connectivity data from a CAD database. The research is concentrated on box-type sheet metal parts primarily made by cutting (e.g., shearing, blanking, punching, etc.), bending, flanging, and local stretching. These parts are produced by both stampers and fabricators.
Computer Based Expert System for Rotating Machinery: Preventive and Predictive Maintenance
Authors: El-Mitwally El-Adawi S. , Rayan M. A. , Mostafa N. H. , Enab Yehia M.
Published: March 2021

At the present time, the maintenance of the equipment becomes an essential task for any production system. This task is becoming more important from both the quantity and the quality points of view, particularly in developing countries. Initiating a maintenance system controlled by the computer will be valuable and effective.

The developed expert system is a combination of an intelligent inference engine matched with a database of information. This system will enable the operator to spot instantaneously the parameters of interest. The expert maintenance system will be designed to perform preventive maintenance tasks and detects faults/failure during the operating cycle. Predictive maintenance enables the operator to minimize the shut down time of faulty equipment and hence increases the productivity. Furthermore, the system will minimize the probable human faults and reduce production costs.
OPGEN: A System to Identify and Evaluate Potential Applications of Knowledge Based Systems
Authors: Rohatgi Samir , Oliver James H. , Chen Stuart S.
Published: March 2021

This paper describes the development of OPGEN (Opportunity Generator), a computer based system to help identify areas where a knowledge based system (KBS) might be beneficial, and to evaluate whether a suitable system could be developed in that area. The core of the system is a knowledge base used to carry out the identification and evaluation functions. Ancillary functions serve to introduce and demonstrate KBS technology to enhance the overall effectiveness of the system. All aspects of the development, from knowledge acquisition through to testing are presented in this paper.
Prolog for Finite-Element Model Definition
Authors: Strooper P. A. , Stylianou M. , Tabarrok B.
Published: March 2021

Finite-Element Analysis (FEA) program vendors go to great lengths to provide their customers with powerful input languages for model definition. The result is a multitude of incompatible input languages. An expert user of one FEA program is merely a novice user of another, primarily because of the different ways vendors implement their input languages. We propose and evaluate the logic programming language Prolog as a language for FEA model definition.
Computer Aided Design of Bucket Type Elevators and Belt Conveyors
Authors: Kilkis Birol , Sager S. Selçuk
Published: March 2021

One of the most effective transportation systems especially for bulk materials is continuous conveyors. They enable to transport materials quickly, economically and with rather simple means of handling. On the other hand for transportation needs involving steep grades and elevations, bucket type elevators are suitable especially for granular materials. In this study a computer program has been developed in order to provide a computer aided design tool for both bucket type elevators and belt conveyors. Operation of the program is interactive. Thus, some critical decisions during the design can be made by the designer, himself. The program has been written in BASIC programming language for Macintosh Plus personal computers. It can be also used in Macintosh II computers. The computer program standardizes all design results and the design conforms the relevant TSE, DIN and ISO standards. All standard tables used in the program, are available in the database. The database can be easily edited and updated. A design report can also be obtained at the end of the design as well as the screen output of the design session.
Development of a Design Automation Software for Crane Design With F.E.M. Rules
Authors: Ünsal Zühal , Erden Abdülkadir
Published: March 2021

A design automation software is developed to use FEM Rules in any crane design procedure. The software (DES_CRANES/FEM_RULES) can be accessed from an automated crane design computer program. Working and loading conditions are transferred to FEM_RULES and computed data, related recommendations and suggested numerical values of some parameters are returned as they are specified in the FEM Rules The software is currently under development to apply in design automation of Overhead Travelling Cranes and Gantry Cranes. DES_CRANES/FEM_RULES also includes some remarks and suggestions derived from various standards for some topics in the FEM Rules.
An Automated Variable Geometry Exhaust Nozzle Design Analysis System
Authors: Wolfe C. E. , Bagepalli B. S. , Bertke J. H.
Published: March 2021

Modern high performance aircraft engines typically have variable geometry nozzles in order to operate at optimal throat areas and throat-to-exit area ratios over a wide range of flight conditions. Designing such a nozzle requires interaction between analysis disciplines such as mechanisms analysis, structural analysis, aerodynamics and thermodynamics. Two issues of importance are reliable data flow between the disciplines and design cycle time. An Exhaust Nozzle Analysis System (ENAS) was developed for evaluating designs of convergent-divergent two-dimensional nozzles. The system incorporates aerodynamic and thermodynamic analyses to allow concurrent engineering, in one automated system mechanism. The system provides the necessary interfaces between analysis codes and between analysis tools and empirical data. While the system described in this paper addresses the design of a single nozzle, the approach is generic and can be applied to any system where a number of disciplines such as mechanism analysis, aerodynamics, structural analysis, and thermodynamics are considered concurrently.
The Development of an Automatic Three-Dimensional Mesh Generator via Modified Ray Casting
Authors: Yeker Cengiz , Zeid Ibrahim
Published: March 2021

A fully automatic three-dimensional mesh generation method is developed by modifying the well-known ray casting technique. The method is capable of meshing objects modeled using the CSG representation scheme.

The input to the method consists of solid geometry information, and mesh attributes such as element size. The method starts by casting rays in 3D space to classify the empty and full parts of the solid. This information is then used to create a cell structure that closely models the solid object. The next step is to further process the cell structure to make it more succinct, so that the cells close to the boundary of the solid object can model the topology with enough fidelity. Moreover, neighborhood relations between cells in the structure are developed and implemented. These relations help produce better conforming meshes. Each cell in the cell structure is identified with respect to a set of pre-defined types of cells. After the identification process, a normalization process is developed and applied to the cell structure in order to ensure that the finite elements generated from each cell conform to each other and to other elements produced from neighboring cells. The last step is to mesh each cell in the structure with valid finite elements.
The SPEx Shell: An Approach to Automating Application and Sales Engineering Processes
Authors: Berry Franklyn , Kott Alexander
Published: March 2021

We define the semi-custom manufacturing business as one in which the product is custom configured from pre-designed components to fit the specific requirements of each customer. Application Engineering is an engineering process of crucial importance in a semi-custom manufacturing business. This process deserves increased automation efforts. The cost and risk of such automation can be significantly reduced by using a shell software which has most of the necessary facilities already built-in. We outline how these facilities are integrated in the SPEx shell. SPEx (Shell for Product Expertise) is a reusable shell software designed to meet the needs of a wide range of product configuration and specification applications. We describe our experience with an Application Engineering automation application built using the SPEx technology.
A High-Performance Method for Comparing CAD Drawing Revisions
Authors: Kanga Darius , Sun William S. , Lee Noel L.
Published: March 2021

This paper describes software developed by the authors to display differences between two revisions of CAD drawings (or 3D models). It processes large CAD files quickly and with moderate memory usage, and it produces output suitable for hard copy as well as on-screen display. The algorithm presented utilizes a sorted key technique that is analyzed to show that while correct results are not guaranteed, the probability of an error occurring is negligible.
Representing Geometric Tolerances in Solid Models
Authors: Guilford James , Turner Joshua
Published: March 2021

ANSI standard Y14.5 defines a set of geometric tolerances to be used to control part variations in manufacturing. With the increasing trend towards replacing drawings with solid models, a representation is needed for expressing these tolerances unambiguously within the context of a solid model.

This representation is complicated primarily by two factors: the drawing tolerances often contain “hidden” information which is not explicitly indicated, but which is inferred by the human reading the drawing; and some of the tolerances implicitly refer to the view of the drawing, which does not exist in a solid model.

This paper discusses several complexities embedded in the standard and proposes ways to address them. It presents a fairly complete coding for geometric tolerances which addresses these complexities. The representation is concise — using only a small number of primitives augmented by a few generally applicable concepts The paper also lists the major areas which the representation does not address.
An Assessment of Assembly Mating Conditions in the Context of a Product Model
Authors: Baxter James E. , Juster Neal P. , de Pennington Alan
Published: March 2021

Recent research at the University of Leeds has concentrated on the role of product models in a design and manufacturing environment. This paper describes initial progress in a project developing a data model that can support applications requiring assembly information throughout a product’s life-cycle. Research by other groups worldwide have used sets of mating conditions to describe the physical connectivity between components in an assembly. However these mating conditions are usually application specific. Experiments have been conducted at Leeds to determine whether these previously reported approaches can form the basis for a set of mating conditions which can be represented in a Product Model from which many applications can draw. The experiments were performed by modelling the relationships between components of a shaft mounted speed reducer by 1) using a set of mating conditions and 2) describing the constraints on the degrees of freedom between pairs of components. The perceived shortcomings of these approaches are discussed.
Three-Dimensional Flow and Transport in a Jet-Driven Rectangular Chemical Vapor Deposition (CVD) Reactor
Authors: LaFleur R. S. , Islam A. K. M. S.
Published: March 2021

The carrier gas flow field of a batch-reactant chemical vapor deposition (CVD) reactor was modeled using the method of images and an analog flow and transport visualization experiment. The current reactor is a rectangular inconel box with argon carrier flow introduced through two corner jets. The reactor was designed such that the argon flow drives active vapor from a bed of batch reactants up to a single flat substrate. Reynolds number and Peclet number similarity were used to determine vapor non-uniformity in the reactor and over the substrate. Method of images computations showed dominant patterns of transport which lead to non-uniform coating potential. Still photographs of transport patterns provided verification of the computational model. The paper provides diagnostic information to develop hardware design improvements.
A Window Based Graphical User Interface for a Supersonic Combustion Fortran Code
Authors: Yip T. Gary , Patel Ajay R.
Published: March 2021

Fortran has been used widely in number crunching applications. In recent years, as the size of application programs increases significantly, users begin to demand interactive capability so that they can interface with the applications in real time in a more flexible and convenient manner. In spite of the wide acceptance by engineers in various fields in the seventies and eighties, Fortran currently does not offer these features. INPUT/OUTPUT are structured rigidly by the order of the READ and WRITE statements in the application programs. The situation would get even worse when the program requires a large number of inputs from the user. A user can use a large input file in which the data must be in a fixed format and no comment statements are allowed. An alternative is to write a real time input interface with requests for inputs displayed on the screen. This leads to a long list of questions and answers scrolling up the screen. When a mistake is made in answering any one of the questions, the input sequence has to be restarted at the beginning of the program again.
A Successive Approximation ADC Simulation Project
Authors: Yip T. Gary , Nadworny Elizabeth B.
Published: March 2021

This paper describes a three week long project designed for first year graduate students in mechanical engineering taking a course in Modern Instrumentation. The project entails constructing a successive approximation analog-to-digital converter without a controller, developing a control sequence, and implementing it to produce a digital representation of an analog input voltage.

The course is made up of a series of laboratory activities that start with the fundamentals of equipment control and data acquisition, then increase in difficulty by requiring students to develop systems and control sequences on their own. The project teaches computer based data acquisition skills, the fundamental logic of a successive approximation ADC, and provides hands on experience using digital signals to control a system.
A Comparative Study of Numerical Techniques for Nonequilibrium Method of Characteristics
Authors: Yip T. Gary , Crook David M. , Buell Timothy P.
Published: March 2021

Three techniques which employ different approaches for obtaining a method of characteristics solution for chemical non-equilibrium flows are reviewed and compared. Two features of the solution process are evaluated to determine their effect on the accuracy of the solution. The first aspect to be considered is the integration of the stiff conservation equations in a unit process. A new fifth-order accurate, multi-step integration routine is contrasted with a first-order accurate, single-step forward differencing scheme. The second comparison is designed to determine if a solution of the flowfield along continuous streamlines is superior to one along discontinuous segments of the streamlines. Tests are performed, using a chemical model describing the supersonic combustion of H2-air. Calculations of single unit processes are used to validate the techniques and to determine suitable grid sizes. Solutions for constant area duct flow show that the techniques which use the multi-step integration routine are more accurate. Results from the constant area duct test, for an initial pressure of 3.685 atm, show that a method of characteristics technique which utilizes continuous streamlines is able to converge at a grid size two orders of magnitude larger than that needed by a technique which uses discontinuous segments of streamlines.
Heater Configuration Design of a Pultrusion Die Using Design Optimization Techniques
Authors: Awa T. W. , West R. L. , Price H. L.
Published: March 2021

The goal of the pultrusion process is to produce a composite material having the desired properties with minimal variation. This requires reliability, uniformity and consistency in production. Key to achieving these requirements is the design of the die and an automated control system. A consistent quality control system can result in greater confidence in the predicted composite properties of the products. The objective of this study is to design the heating configuration for an existing pultrusion die. The design optimization technique is used to synthesize the heating configuration of a laboratory scale die to produce the required production temperature profile for a pultrusion process. The heating configuration includes three variables, which are the number of heaters, power input and location of the heaters. The scope of the design optimization method is to choose the number of heaters, the input power and heater location to minimize the error between the calculated and desired production temperature profile.
Analysis of Pressure Suppression Pool Swell Using Microcomputers
Authors: Saha P. , Rakshit B. K. , Mukhopadhyay P.
Published: March 2021

The present paper discusses the development of a computer software or code for a best-estimate analysis of Pressure Suppression Pool Hydrodynamics in a Pressurized Heavy Water Reactor (PHWR) system during a Loss-of-Coolant Accident (LOCA) at the primary heat transport system. The software has been developed on Microcomputers, namely, PC-XT or AT (286) under MS-DOS operating system.
A Nonorthogonal Grid System and its Application to Fluid and Heat Transfer Problems
Authors: Halal Afif S. , Lilley David G.
Published: March 2021

The study focuses on the fundamental nonorthogonal grid coverage of an axisymmetric flow domain with irregular boundaries, and involves incorporating swirl and turbulence effects into a stream function-vorticity simulation. Turbulence is simulated by way of a two-equation k-e turbulence model, together with wall functions for the treatment of near-wall flows. The finite difference equations are derived at points of a general boundary-fitted nonorthogonal grid using displaced, linear, and quadratic interpolation. The solution procedure is implemented in a new computer code which features generalized boundaries, rectangular and/or nonrectangular grids, swirl, turbulence, time-dependent calculations, and adaptive stability. Model evaluation is accomplished through a comparative study between predictions and available experimental data.
Effect of Engine Operating Parameters on Combustion and Emission Characteristics
Authors: Lu Jiang , Gupta Ashwani K. , Keating Eugene L.
Published: March 2021

Numerical simulation of flow, combustion, heat release rate and pollutants emission characteristics have been obtained using a single cylinder internal combustion engine operating with propane as the fuel. The data are compared with experimental results and show excellent agreement for peak pressure and the rate of pressure rise as a function of crank angle. The results obtained for NO and CO are also found to be in good agreement and are similar to those reported in the literature for the chosen combustion chamber geometry. The results have shown that both the combustion chamber geometry and engine operating parameters affects the flame growth within the combustion chamber which subsequently affects the pollutants emission levels. The code employed the time marching procedure and solves the governing partial differential equations of multi-component chemically reacting fluid flow by finite difference method. The numerical results provide a cost effective means of developing advanced internal combustion engine chamber geometry design that provides high efficiency and low pollution levels. It is expected that increased computational tools will be used in the future for enhancing our understanding of the detailed combustion process in internal combustion engines and all other energy conversion systems. Such detailed information is critical for the development of advanced methods for energy conservation and environmental pollution control.
Modal Orthogonality Applied to Design of Spatially Shaped Distributed Sensors
Authors: Tzou H. S. , Natori M. , Zhong J. P.
Published: March 2021

Observation spillover resulting from sensing signals often introduces structural instability of undamped structural systems. One method to prevent the spillover problem is to use spatially distributed modal sensors in which the effects of residual modes are filtered out. In this study, a modal filtering theory for a generic shell continuum, based on modal orthogonal functions, is derived. The sensor signals are contributed from membrane strains and bending strains of the piezoelectric distributed sensor on the shell continua. This theory is applied to a design of cosine shaped convolving sensors for a circular ring structure. Performance of the distributed convolving sensors is studied. Bending and membrane (circumferential) sensitivities of the convolving ring sensors are defined.
Triangulated Surface Construction From Scattered 3-D Points
Authors: Vajapeyam Sridhar , Keefe Michael
Published: March 2021

A three-dimensional analog to the Gabriel Graph structure is defined and an algorithmic procedure for the construction of a triangulated surface from scattered data points in three dimensions is developed based on the concept on three-dimensional Gabriel Graphs. The algorithm does not require the points to be in the form of a grid or on contours. The closest point 3-D Delaunay triangulation of the points is first constructed and the Delaunay triangles that satisfy the Gabriel Graph criterion are identified. From this set of triangles, extraneous triangles are removed, resulting in a triangulated open surface passing through all the given data points. This surface can then be subjected to smoothing algorithms if necessary and a smooth surface of the desired continuity can be constructed using available interpolation techniques. The algorithm can be used for constructing surfaces from scattered data in mechanical design, geographic terrain modeling and modeling biological surfaces from CT scans and MRI scans.
p-Version Axisymmetric Shell Element for Geometrically Nonlinear Analysis
Authors: Liu Joseph H. , Surana Karan S.
Published: March 2021

This paper presents a p-version geometrically nonlinear (GNL) formulation based on total Lagrangian approach for a three node curved axisymmetric shell element. The approximation functions and the nodal variables for the element are derived directly from the Lagrange family of interpolation functions of order pξ and pη. This is accomplished by first establishing one dimensional hierarchical approximation functions and the corresponding nodal variable operators in the ξ and η directions for the three and one node equivalent configurations that correspond to pξ + 1 and pη + 1 equally spaced nodes in the ξ and η directions and then taking their products. The resulting element approximation functions and the nodal variables are hierarchical and the element approximation ensures C0 continuity. The element geometry is described by the coordinates of the nodes located on the middle surface of the element and the nodal vectors describing top and bottom surfaces of the element.

The element properties are established using the principle of virtual work and the hierarchical element approximation. In formulating the properties of the element complete axisymmetric state of stresses and strains are considered hence the element is equally effective for very thin as well as extremely thick shells. The formulation presented here removes virtually all of the drawbacks present in the existing GNL axisymmetric shell finite element formulations and has many additional benefits. First, the currently available GNL axisymmetric shell finite element formulations are based on fixed interpolation order and thus are not hierarchical and have no mechanism for p-level change. Secondly, the element displacement approximations in the existing formulations are either based on linearized (with respect to nodal rotation) displacement field in which case a true Lagrangian formulation is not possible and the load step size is severely limited or are based on nonlinear nodal rotation functions approach in which case though the kinematics of deformation is exact but additional complications arise due to the noncummutative nature of nonlinear nodal rotation functions. Such limitations and difficulties do not exist in the present formulation. The hierarchical displacement approximation used here does not involve traditional nodal rotations that have been used in the existing shell element formulations, thus the difficulties associated with their use are not present in this formulation.

Incremental equations of equilibrium are derived and solved using the standard Newton-Raphson method. The total load is divided into increments, and for each increment of load, equilibrium iterations are performed until each component of the residuals is within a present tolerance. Numerical examples are presented to show the accuracy, efficiency and advantages of the present formulation. The results obtained from the present formulation are compared with those available in the literature.
p-Version Two Dimensional Beam Element for Geometrically Nonlinear Analysis
Authors: Orth Fabian J. , Surana Karan S.
Published: March 2021

This paper presents a p-version geometrically nonlinear formulation (GNL) based on total Lagrangian approach for a three node two dimensional curved beam element. The hierarchical element approximation functions and the corresponding nodal variables are derived directly from the Lagrange family of interpolation functions. The resulting element displacement approximation is hierarchical and can be of arbitrary and different polynomial orders in the longitudinal and the transverse directions of the beam element and ensures C0 continuity. The element geometry is described by the coordinates of the nodes located on the axis of the beam (middle surface) and the nodal vectors describing the top and bottom surfaces of the element.

The element properties are established using the principle of virtual work and the hierarchical element displacement approximation. In formulating the properties of the element complete two dimensional stresses and strains are considered hence the element is equally effective for very slender as well as extremely deep beams. Incremental equations of equilibrium are derived and solved using the standard Newton-Raphson method. The total load is divided into increments, and for each increment of load, equilibrium iterations are performed until each component of the residuals is within a preset tolerance. Numerical examples are presented to show the accuracy, efficiency and advantages of the present formulation. The results obtained from the present formulation are compared with those reported in the literature.

The formulation presented here removes virtually all of the drawbacks present in the existing GNL beam finite element formulations and has many additional benefits. First, the currently available GNL beam formulations are based on fixed order of approximation for the displacements and thus are not hierarchical and have no provision for changing the order of approximation for the displacements u and v. Secondly, the element displacement approximations in the existing formulations are either based on linearized displacement field for which a true Lagrangian formulation is not possible and the incremental load step size is severely limited or are based on nonlinear nodal rotation function approach in which case even though the description of displacement for the element is exact but additional complications arise due to the noncummutative nature of nonlinear nodal rotation functions. The p-version displacement approximation used here does not involve traditional nodal rotations that have been used in the existing beam formulations, thus the difficulties associated with their use are not present in this formulation.
Simplified Thermal Analysis for Embedded Piping
Authors: Joodi Pirooz M. H.
Published: March 2021

The growing use of tubular structures in nuclear reactor facilities such as pipes, conduits and ducts that are buried underground, requires more detailed stress analysis to demonstrate structural integrity as required by Section III of the Boiler Pressure Vessel Code and other applicable industry codes.

Thermal behavior of the pipe and soil interference can be conservatively evaluated by implementing the thermal characteristics and properties of the pipe into the expressions, as deduced by previous studies, which are made for the seismic analysis of buried piping. This paper presents procedures to evaluate the different pipe/soil parameters to be applied in those expressions, and explains these equations from designers perspectives and, finally, suggests an approach to combine various pipe stresses to check against ASME Boiler and Pressure Vessel Code Section III. The analysis assumes that the soil is linearly elastic and homogenous and the structure is a straight slender solid or hollow beam with a uniform, symmetrical cross section that satisfies the conditions of the elementary theory of beams on elastic foundations.
On the Flow Start-Up in Convergent-Divergent Nozzles
Authors: Opalka Klaus-Otto
Published: March 2021

Shock lube tests were carried out to investigate the influence of the divergent half angle of four planar convergent-divergent nozzles on the incident-shock formation, and on the pressure signature downstream from the nozzle. A diaphragm was mounted in the throat of these nozzles and located at the upstream edge of the test section window of high-quality optical glass through which shadowgraphs and schlieren pictures could be taken. The objectives of this investigation were to obtain optical records of the flow start-up processes in these divergent nozzles immediately after rupturing the diaphragm, and to facilitate comparisons with hydrocode computations. The optical measurements were complemented by measurements of the static pressure at three locations downstream from the nozzles. The test set-up and the results of these experiments are presented and compared with the results of one dimensional hydrocode computations.
Teaching the Concept of Total Design
Authors: Echempati Raghu
Published: March 2021

When the engineering students graduate and are about to enter the “real world of engineering” — be it an engineering industry (as a coop or as an engineer), or return to an educational institution for further studies, they must appreciate and possibly be already familiar with the concept of “Total Design of the Mechanical System”. This means that the students be given excellent training before they graduate, to fulfil the current and the future needs of an industry.

This paper presents the methodology adopted by the author based on his own experience as a consultant to an industry, in teaching 2 different design courses at the Michigan Technological University. The feedback obtained (from time to time) from the student alumni has been a totally rewarding experience.
Enhancing Product Development Teaching With a Computer-Aided Product Development Guide
Authors: Wilson Clement C. , Kennedy Michael E.
Published: March 2021

By many measures, U.S. industry is no longer the leader in developing world class products. U.S. product development and manufacturing systems need substantial improvement to assure a successful future. The Superior Engineering Design Program (SEDP) was created within the University of Tennessee’s College of Engineering in 1987, with a mission to improve the teaching and practice of product development. Within this program, the authors have developed a computer-based learning tool, the “SEDP Product Development Guide” (“the Guide”), to help senior and graduate engineering design students learn “superior” product development processes.

The Guide incorporates the latest product development strategies and techniques, as practiced by some of industry’s most competitive product development teams. The software is an assistant, but is specifically not an “artificial intelligence” system that purports to make decisions for the user. Rather, the guide provides structure and asks “critical” questions at appropriate times during the product development process. While design tools are available for assistance, the student engineer is always responsible for answering the “critical questions” satisfactorily to assure that the designed product meets customer requirements.

A prototype SEDP Product Development Guide has been installed for evaluation in the SEDP’s Engineering Design Center, located in the University’s Mechanical and Aerospace Engineering Department.
Energy Optimal Control Algorithm Based on Central Difference Approximation of Equation of Motion With Application to Robot Control
Authors: Nakhaie-Jazar Gholamreza , Naghshineh-Poor A. H. , Ravanbakhsh K.
Published: March 2021

Optimal control of robotic manipulator has a complex nature. Many different control and optimal control algorithms have been developed. However, these algorithms are either based on simplified equation of motion or are tedious to implement to set up.

In this work the equations of motion are approximated by central difference technic and Taylor series expansion, while path of motion is divided in finite segments. The motion is assumed to have zero velocity at beginning and at the end of the motion, without loss of generality. The whole time and path of motion is arbitrary, but fixed, after the option. The problem of energy optimal control is reduced to minimizing a scalar function of many but finite variables with equality and inequality constraints. By applying modified Hooke and Jeeves method, actuator torques at any time are calculated.

The preparation time for problem set up and execution time are small, and programming efforts are reasonably low.

The algorithm is implemented for a 2R and 3R robotic manipulator, and results are presented.
Computer Control of Turning Center and Industrial Robot
Authors: Hua Xun
Published: March 2021

This presents a computer control system for a turning center workstation in Computer-integrated Manufacturing Systems (CIMS) environment. The system structure is first introduced. Then, an information exchange between different devices inside the workstation is studied. These devices are made by different manufacturers so that the communication between them becomes a problem. The principle of developing a software to implement the communications is presented, which includes the use of a software platform, the development of data acquisition system (DAS) for robots, and the writing of an information request. Finally, the operations of the system is presented.
A Study on a High-Speed NC Gear Grinding Machine Using Screw-Shaped CBN Wheel
Authors: Emura T. , Wang L. , Arakawa A.
Published: March 2021

This paper describes a basic study for the development of a high-speed NC gear grinding machine using screw-shaped CBN wheel.

Gear grinding machines using screw-shaped grinding wheel have already developed by Reishauer and others. However, their productivity is not high, because they use one thread type grinding wheel and the rotary speed of the workspindle is very low.

The maximum rotary speed of the grinding spindle developed by the authors is 12,000 rpm and that of workspindle is 3,000 rpm. They are enough speed for gear grinding. The desired accuracy for an angle sensor of grinding spindle is more than 20 ″pp in the case of the multithread type grinding wheel. The ordinary shaft encoder cannot respond at such a high-speed. Therefore the authors used a magnetic scale of high-accuracy and an induction type magnetic head. After experiments, it became clear that two-phase type PLL proposed by T. Emura is useful for detecting low level signals obtained from the magnetic head.

Since the maximum rotary speed of the workspindle is raised to 3,000 rpm, we cannot use any reduction gear. Thus a direct-drive method with an inertial damper was used. The workspindle is controlled by using the two-phase type PLL.

When we grind gears, the initial setting between rotary angles of grinding wheel and work is required. The authors tried to automatically set the initial rotary angles by using a CCD camera and a microcomputer.
Dynamic Analysis of a Planetary Gear System
Authors: Donley Mark G. , Steyer Glen C.
Published: March 2021

Noise reduction in geared systems is usually achieved by minimizing transmission error or by changing the gear train’s dynamic response. While considerable research has been directed in the past to understanding and controlling the transmission error, the same can not be said of the system dynamic response. Recent efforts at modifying the dynamic response to reduce the sensitivity to transmission error have proven to be very rewarding for parallel shaft gearing applications.

In this paper, these efforts are extended to planetary gear set applications. A major difference between planetary gear sets and parallel shaft gears is that in planetary gear sets many gear meshes carry load instead of just one. This feature poses a modeling problem as to how to combine responses due to transmission errors at each loaded mesh to determine the total response. A method is proposed in this paper in which transmission errors at different gear meshes are combined into net vertical, net lateral and net tangential transmission errors. A methodology for computing dynamic mesh force response due to these net transmission errors and for identifying critical components that control the gear train system dynamics is presented. These techniques are useful in understanding the effects of system dynamics on gear noise and in developing quiet gear design. To demonstrate the salient features of the proposed method, an example analysis of a transmission with a planetary gear set is presented.
A Comparative Study of Selected Gear Mesh Interface Dynamic Models
Authors: Blankenship G. Wesley , Singh Rajendra
Published: March 2021

There is a consensus among modern gear researchers that variation in gear mesh stiffness and transmission error are the primary sources of vibratory excitation in most moderately to heavily loaded gear drives. However, several schools of thought exist in the literature on how to incorporate these mesh stiffness and transmission error concepts into a dynamic model. In this paper, a formal expression for an elastic gear mesh force vector is developed and selected gear mesh interface models, which exemplify most of the common modeling approaches in use today, are compared on a common mathematical basis. The various modeling strategies, their inherent philosophies and assumptions are made clear. All of the models examined employ a common spatial domain analysis methodology which pervades the field of modem gear dynamics. The focus of this study is limited to the quasi-steady state, non-resonant dynamic analysis of a single involute gear pair operating below critical shaft speeds such that shaft whirling and gyroscopic effects are negligible, and under loading conditions sufficiently high to prevent loss of tooth contact due to gear backlash phenomenon. The need for extended analytical models, which consider multi-dimensional excitation and better describe force transmissibility via the gear mesh interface, is identified. This forms the basis of an on-going comprehensive investigation which expects to clarify several unresolved issues in gear dynamic modeling; future publications will report such studies.