bluuebunny/crossref_metadata_2025 huggingface dataset:
Abscisic acid crosstalk with auxin and ethylene in biosynthesis and degradation of inulin‐type fructans in chicory
Authors: Mohammadi F. , Naghavi M. R. , Peighambari S. A. , Khosravi Dehaghi N. , Khaldari I. , Bravi E. , Marconi O. , Perretti G.
Published: March 2021

The effect of different hormones on fructan accumulation and the genes regulating biosynthesis and degradation is known; however, information on hormonal interaction mechanisms for fructan content and mean degree of polymerization (mDP) is limited.

Cell suspension cultures of chicory were prepared and treated with abscisic acid (ABA), auxin (AUX), ethylene (ETH), ABA + AUX or ABA + ETH, then inulin concentration, mDP of inulin and expression of FAZY genes was determined.

A low concentration of AUX and ETH increased fructan content, while a high concentration of AUX and ETH decreased it. Exogenous ABA increased mDP of inulin and this coincided with the low expression of 1‐FEHII. In hormone interactions, ABA changed and adjusted the effect of both AUX and ETH. ABA, together with a low level of AUX and ETH, resulted in a decrease in inulin content and increase in mDP, which coincided with low expression of FEHII. ABA together with a high level of AUX and ETH caused an increase in inulin content with a lower mDP, which coincided with high expression of biosynthesis (1‐FFT) and degradation (1‐FEHII) genes.

The effect of both AUX and ETH was almost the same, although the effect of ETH was more severe. ABA had a modulating role in combinations with AUX and ETH. Among biosynthesis and degradation genes, the expression of 1‐FEHII was more affected by these hormones.
Simulating multi‐exit evacuation using deep reinforcement learning
Authors: Xu Dong , Huang Xiao , Mango Joseph , Li Xiang , Li Zhenlong
Published: March 2021

Conventional simulations on multi‐exit indoor evacuation focus primarily on how to determine a reasonable exit based on numerous factors in a changing environment. Results commonly include some congested and other under‐utilized exits, especially with large numbers of pedestrians. We propose a multi‐exit evacuation simulation based on deep reinforcement learning (DRL), referred to as the MultiExit‐DRL, which involves a deep neural network (DNN) framework to facilitate state‐to‐action mapping. The DNN framework applies Rainbow Deep Q‐Network (DQN), a DRL algorithm that integrates several advanced DQN methods, to improve data utilization and algorithm stability and further divides the action space into eight isometric directions for possible pedestrian choices. We compare MultiExit‐DRL with two conventional multi‐exit evacuation simulation models in three separate scenarios: varying pedestrian distribution ratios; varying exit width ratios; and varying open schedules for an exit. The results show that MultiExit‐DRL presents great learning efficiency while reducing the total number of evacuation frames in all designed experiments. In addition, the integration of DRL allows pedestrians to explore other potential exits and helps determine optimal directions, leading to a high efficiency of exit utilization.
Biochemical and blood gas alterations in buffalo (Bubalus bubalis) whole blood stored in CPDA‐1 and CPD/SAG‐M bags
Authors: Nunes Neto Osvaldo Gato , de Alencar Silva Thamiris Souza , Sousa Rejane Santos , Morini Adriana Caroprezo , Pinto Gilson Andrey Siqueira , de Oliveira Francisco Leonardo Costa , Ortolani Enrico Lippi , Portela Juliana Machado , Barrêto Júnior Raimundo Alves , Minervino Antonio Humberto Hamad
Published: March 2021

Objective

The objective of this study was to evaluate the biochemical and blood gas alterations of whole blood of buffaloes that was stored in citrate–phosphate–dextrose with adenine (CPDA‐1) and CPD/SAG‐M blood bags for 42 days.

Design

Prospective study.

Interventions

Ten male buffaloes were used in this study. A total volume of 900 mL of blood was collected from each buffalo so that 450 mL was stored in CPDA‐1 and 450 mL was stored in CPD/SAG‐M bags at 2–6°C for 42 days. The stored blood was evaluated at 7 time points (D): D0 (immediately after blood collection) and 7 (D7), 14 (D14), 21 (D21), 28 (D28), 35 (D35), and 42 (D42) days after collection. Blood gas, biochemical, and microbiological parameters were monitored.

Measurements and main results

The overall blood pH decreased from 6.997 ± 0.05 at D0 to 6.784 ± 0.09 at D42, differing from baseline from D14 onward (P < 0.05). There were increases in partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), lactate, and potassium (K) and decreases in the concentrations of sodium, bicarbonate, glucose, and pH (P < 0.05) during storage in both bags but no alterations in total protein concentration. Most of the variables were consistently similar between the 2 types of blood bags (P > 0.05) evaluated, with the exception of pCO2, HCO3, cholesterol, and total protein, which had higher values in the CPDA‐1 bag (P < 0.05). The K, pO2, and lactate had the highest alterations during storage, with increases from baseline to D42 of 563%, 317%, and 169%, respectively.

Conclusion

In general, no significant changes of clinical importance were observed after storage of whole blood samples from buffaloes for 42 days in the 2 types of blood bags that are indicated for use with this species.
Zürich cementless total hip arthroplasty as a treatment option for capital physeal fractures in dogs: Outcome in 53 cases
Authors: Alvarez‐Sanchez Alejandro , Amsellem Pierre , Vezzoni Luca , Vezzoni Aldo
Published: March 2021

Objective

To review the outcome of dogs that underwent Zürich cementless total hip arthroplasty (Z‐THA) for the repair of acute and chronic capital physeal fractures (CPF) and document the CPF‐related hip remodeling.

Study design

Retrospective study.

Sample population

Fifty‐three Z‐THA in 53 dogs.

Methods

Medical records of dogs (2006‐2019) that underwent Z‐THA for CPF management were reviewed. Dogs were divided into two groups on the basis of the days elapsed between CPF diagnosis and Z‐THA, acute (≤30 days) and chronic (>30 days). Hip remodeling variables were determined from preoperative radiographs or intraoperatively. Descriptive statistics were performed, and the complication rates, outcome, and coxofemoral remodeling were recorded. Comparisons of remodeling variables and rates between groups were performed by using Fisher's exact test.

Results

In total, 23 of 53 (43.4%) cases were acute, and 30 of 53 (56.6%) cases were chronic. There was no difference in the femoral remodeling rates between the acute and chronic groups (P = .184), whereas acetabular remodeling was more prevalent in the chronic group (P < .001). Intraoperative complications occurred in four of 53 (7.5% [1/23 acute, 3/30 chronic]) cases, and postoperative complications occurred in six of 53 (11.3% [2/23 acute, 4/30 chronic]) cases. Good clinical outcomes were achieved in 51 of 53 (96.2% [21 acute, 30 chronic]) cases.

Conclusion

Complication rates of Z‐THA for CPF repair were similar to the complication rates reported for Z‐THA of dysplastic hips. Hip remodeling was common regardless of CPF chronicity.

Clinical significance

Zürich cementless total hip arthroplasty is viable for surgical management of CPF. There is a high likelihood that hip remodeling will be encountered, even in fractures treated within 30 days of presenting for hind limb lameness.
Impact of a Mass on a Damped Elastically Supported Beam
Authors: Hoppmann W. H.
Published: March 2021

In this paper a study is made of the problem of the central impact of a mass on a simply supported beam on an elastic foundation with considerations of internal and external damping. The differential equation for the forced vibration of the beam is developed. It is solved for the case in which the force is a function of time and is concentrated at the center of the beam. Formulas are obtained for the deflections. An expression is developed for the coefficient of restitution which is essential in determining the deflections and the strains. Criteria are devised for determining the cases in which the beam may be considered as a single-degree-of-freedom system when damping and an elastic foundation are considered. The importance of these criteria is discussed. A numerical example illustrating the theory developed in the paper is worked out in detail. Results of computations for several numerical solutions are given in tabular form.
Tables for Numerical Solution of Problems in Compressible Gas Flow With Energy Effects
Authors: Shapiro Ascher H. , Edelman Gilbert M.
Published: March 2021

Tables of functions are given for solving problems in one-dimensional, compressible gas flow when energy effects, as represented by changes in stagnation temperature, are involved. The tables may be used for such typical processes as heat transfer at high gas speeds, combustion, moisture condensation shocks, flame fronts, and detonation waves. The Mach number is the independent argument of the tables, and there is one table for each of six specific-heat ratios, namely, 1.0, 1.1, 1.2, 1.3, 1.4, and 1.67.
Centrifugal and Thermal Stresses in Rotating Disks
Authors: Leopold W. R.
Published: March 2021

A general semigraphical method, a combination and continuation of the solutions indicated by Stodola and Timoshenko, was found by which the thermal and centrifugal stresses in a rotating disk of any arbitrary profile could be determined. This relatively simple and rapid method of solution requires for its application elementary arithmetic involved in the completion of a tabular form sheet, a temperature gradient along the radius of the disk, which may be approximated by an exponential function of the radius, and easily accommodates changes in the physical properties of the disk material at elevated temperatures. A disk profile and expected radial temperature gradient, as determined from heat-transfer analysis, were taken as an example, and the complete disk stresses calculated directly to demonstrate the use of the method.
Large Cylindrical Bending of Rectangular Plates
Authors: Lang H. A.
Published: March 2021

This paper develops a “power-series” method which may be applied to the bending and buckling, of long, thin, rectangular plates when the deflection and curvature are large and the loading is a function of the transverse coordinate only. The method depends upon the constancy of a certain quantity, N + M2/2, whenever the loading is continuous. The condition of continuity may be removed and the results applied to any general loading. Explicit expressions, to any degree of accuracy, are obtainable for the bending moment, transverse force, and deflection. The method is applied to verify the theory of bending of a plate under uniform load, edges clamped or pinned. The problem of the elastica and the effect of discontinuous loads are discussed briefly.
Fast Data-Driven Model Predictive Control Strategy for Connected and Automated Vehicles
Authors: Bhattacharyya Viranjan , Canosa Alejandro Fernandez , HomChaudhuri Baisravan
Published: March 2021

We present a fast data-driven model predictive control (MPC) strategy for connected and automated vehicles, which can ensure collision avoidance in the presence of uncertainty in shared/predicted trajectory of preceding vehicles. The proposed control strategy focuses on improvement in fuel economy and computational efficiency. We exploit a data-driven modeling approach to identify a linear predictor for the nonlinear system and evaluate a deterministic equivalent of the probabilistic collision avoidance constraint to formulate the equivalent convex optimal control problem. We then develop a hierarchical control framework with sampling-based high-level control and fast MPC-based low-level control. Simulation results show the efficacy of the proposed approach both in terms of computation time and fuel efficiency.
Product Modeling System With a Constraint Solver Among Attributes
Authors: Minami Shunsuke , Ishida Tomotoshi , Shinotuka Yoshiaki , Hirakata Junko , Inoue Atsushi
Published: March 2021

A computer-aided design (CAD) system called “Product Modeler” is described for domain-specific product modeling. Product modeling requires construction of user-specific models of design objects. Then, the Product Modeler is a general purpose tool implemented on a general purpose CAD system, which is a solid modeling system in this paper. The system manages CAD data, e.g. shape data, and user-specific data, e.g. domain-specific design rules, as attributes and constraints. Users can describe their design models by user-defined data and constraints among these data, and among these data and the CAD data. The Product Modeler handles the CAD data as data with side-effects and integrates the CAD data and user-defined data constraints by calling the CAD procedure automatically. As an example, a product model for motion and mechanism design of power shovels is prepared using the Product Modeler to show how to implement the user-specific design model.
Hyper-Can: An Automated Design and Analysis Tool for Packaging-Specific Applications
Authors: Bhakuni Nila D. , Dick Robert E. , Beiter Kurt A.
Published: March 2021

The objective of beverage and food can design is to minimize cost while maintaining structural integrity. The package must satisfy requirements of internal pressure, drop pressure, and axial column load. Finite element analysis allows the designer to examine these structural constraints before prototypes are created so a larger design space can be examined in a shorter time. Hyper-Can was created as a tool in the Macintosh environment to automate the design and analysis process and reduce the design cycle time in a user-friendly way. Hyper-Can contains templates or families of designs of standard beverage and food can ends and bodies that calculate geometric information for finite element analysis pre-processing and fill and metal volume calculation using external Fortran code. Hyper-Can allows the designer to manipulate a standard design from the conceptual stage to analysis utilizing a simple graphical interface on the Macintosh.
Development of a 2-D Fixturing Planner for Prismatic Parts for a Flexible Fixturing System
Authors: Zhang Qiyi , Greenway R. Bryan , Faddis Terry N.
Published: March 2021

This paper describes an planning system developed for a 16-hole flexible fixturing device previously developed at the University of Kansas’ Computer-Integrated Manufacturing Laboratory (KUCIM). Based on the fixture baseplate and newly designed fixturing elements, a 2-D fixturing planner program was developed to determine and display the fixturing configuration for workpieces of a certain geometric shape and size. The planner output can be either used to direct an operator in the manual setup of the fixture or to command the manufacturing cell’s robot to conduct the fixturing assembly automatically.
Advanced Spreadsheet Methods for Mechanical Engineers
Authors: Dartt Randall F. , Eggert Rudolph J.
Published: March 2021

Spreadsheets are a useful supplement to the set of “tools” available to the mechanical engineer for design and analysis. They are well suited and convenient to the computational needs of the profession, providing many advantages over commonly applied methods, and in our opinion are presently underutilized by mechanical engineers.

To take full advantage of the inherent applicability of spreadsheets to mechanical engineering, proper programming and calculational methodology must be followed to assure usefulness, accuracy, and general versatility. The many features and functions of modern spreadsheet packages, coupled with the ability to produce custom addin functions, may be used to develop advanced procedures which may be applied to any number of engineering situations, providing solutions to problems that might prove inconvenient or intractable using other methods. Using spreadsheets, solutions become available as immediate, presentation quality visual and hardcopy feedback.

The combination of calculational speed and visual output produce a highly interactive process by which the optimization process may occur as a parallel procedure to design, as opposed to one performed subsequently to the initial design process. This document will introduce guidelines, methodology and examples by which spreadsheets may be utilized by mechanical engineers for design and analysis.
Anthropometry-Based Surface Modeling of the Human Torso
Authors: Li Peng , Jones Peter R. M.
Published: March 2021

There is an increasing need for computerized surface model of the human body in human growth, garment design and ergonomics. However, there is a shortage of three-dimensional (3-D) models of the human body in practical applications. This paper presents a new approach for constructing a 3-D surface model of the human torso using anthropometry. The torso is created by from a reference body of average shape which is represented by a family of cross-sectional curves. The shape and size of the reference body can be modified according to anthropometric data. This approach has been implemented on a personal computer. The resulting 3-D model is a parametric surface based on non-uniform B-splines and can easily be exported to other computer aided design applications.
A Comparative Study of Flux Projection Type Error Estimators in Elasto-Plastic Finite Element Analysis
Authors: Tetambe Ravi P. , Saigal Sunil
Published: March 2021

This paper presents a comparative study of a series of flux projection type error estimators for elastio-plastic materials undergoing large strains and large rotations. The error estimators are: L2 norms of stress error, total strain error, equivalent strain error, incremental total strain error per load step, and energy rate norm error, respectively. Numerical examples are presented in two dimensions. The information provided by these error estimators may be used for adaptive mesh refinement and for subsequent data transfer (rezoning) in a large deformation analysis. The error estimators based on the energy rate and the incremental total strain were found to be accurate in the prediction of the discretization error for the test cases considered. The L2 norm of incremental strain error estimator consistently gave the most conservative estimate of error.
Challenge Face by Truck Frontal Crash Analysis
Authors: Cheng James C. , Le Jialiang
Published: March 2021

In the front barrier crash, due to basic structural differences, light truck body-on-frame vehicles behave quite differently man unitized body vehicles. The complexities of the vehicle structure, weight variation of the test condition, and inherent limited crash distance have made CAE analysis a very attractive method to reduce prototype testing and shorten the design cycle time. The deceleration of the vehicle experienced by the occupant, or “crash pulse”, plays a key role in evaluating occupant injury. In order to maximize CAE’s contribution to design, a reasonable prediction of the crash pulse is crucial. For body-on-frame vehicles, body mounts that connect the cab to the chassis have a pronounced effect on the crash pulse. However, the crash characteristic of the body mount is not fully understood. Therefore, a procedure was developed to provide a good estimation of their behavior. This procedure uses a spring-mass model and a finite element model to simulate a frontal barrier crash test. In both models, the body mounts were modeled as nonlinear springs. By correlating the vehicle response at different locations, a reasonable prediction of the body mounts can be obtained. Further design iterations can be performed once the body mounts characteristic is determined.
Bulk Forming Simulation on High Performance Computers
Authors: Cheng Wing L.
Published: March 2021

Modeling of complicated three-dimensional bulk forming processes remains a challenge to scientists and engineers. Not only does it require a good mathematical model which gives an accurate geometric representation of the dies and the work-piece to capture the physics of the forming processes, it also needs the appropriate computers to carry out different parts of the modeling effort including the numerical simulation. This paper describes our experience on a computer analysis of a three-dimensional multi-stage forging process using an explicit finite element program and a combination of graphic workstations and supercomputers. A three-stage forging of a valve body was used to illustrate the simulation process. A Scalar Graphic Workstation was used in geometric modeling, numerical calculations for the first two stages of the forging process when a coarse model was adequate, and post-processing of the results. A CRAY Y-MP Supercomputer was required to simulate the third stage of the forging process when a fine mesh was needed to capture the details of the material flows. Data transfer was accommodated by a full T-1 communication line between the supercomputer and the workstation. The availability of the advanced software tools and these computer resources provides us the ability to model an entire range of bulk forming problems.
Flowfield Prediction and Color Graphic Interpretation
Authors: Dong M. , Lin T.-K. , Lilley D. G.
Published: March 2021

A computer code has been developed to simulate the turbulent combustion flowfield of an axisymmetric swirling flow in a typical combustor. Fuel enters centrally through a round cross-sectioned inlet while air enters through a concentric annular injet. Combustion flowfield predictions are given to illustrate the reacting flowfield prediction with color graphic interpretation of the results. One, two and four-step chemical schemes are used for the combustion simulation based on Arrhenius and Eddy-Break-Up concepts. Turbulence simulation is by way of the standard two-equation k-e model. Results compare favorably with available experimental data, and are easily interpreted via a newly-developed combustor flowfield color display.
Axially Lumped Versus Axially Distributed Modeling of Liquid-to-Gas Cross-Flow Heat Exchanger Transients
Authors: Elissa M. G. , Rooke S. P.
Published: March 2021

Thermal transients of single-row finned-tube serpentine liquid-to-gas cross-flow heat exchangers utilizing single phase fluids are examined numerically in the temperature-time domain. Two modeling approaches are examined with the aim of contrasting levels of modeling sophistication for this specific heat exchanger application. One model is axially lumped (cases with more than one lump are examined), and the second model is axially distributed. The lumped model is solved using a 4th order Runge-Kutta integration scheme, and the distributed model is solved using an explicit upwind differencing scheme. Single lump representation is found to be undesirable, while multi-lump representation provides adequate comparison with the distributed model. Computation times become an issue for the lumped model if multiple lumps are solved using the 4th order Runge-Kutta scheme.
Computer Simulation of Aerosol Motion
Authors: MacGibbon Bruce S. , Busnaina Ahmed A.
Published: March 2021

This paper is a general review of aerosol dynamics. A Lagrangian equation of motion is presented that incorporates forces that may act on a particle. Included are the influences of viscous drag, gravity, lift, brownian motion, thermophoresis, electrophoresis, photophoresis, and turbulence. Using the equation of motion, particle trajectories can be numerically simulated for given fluid conditions.
Computer Aided Simulation of Turbulent Flow in Pulsate Jet Nozzle
Authors: Li Zheng , Geskin E. S.
Published: March 2021

In this paper, the method of computational fluid dynamics are employed for examination of the formation of a pulsate turbulent waterjet in a Helmholtz resonator type nozzle. The analysis is based on the numerical solution of the conservation equations of mass and momentum, and the standard k-ε turbulent model. The evaluation of the flow characteristics within the nozzle is carried out. Also, the experiments show substantial advantages of this nozzle over a conventional waterjet as a machining tool. The end results of this work will be a knowledge necessary for the improvement of nozzle design and better formation of water and slurry jet.
Integrating Microcomputer Applications Into Engineering Technology Programs
Authors: Kitto Kathleen L.
Published: March 2021

Engineering students graduating today face a fast-paced, competitive marketplace where the push to reduce cycle times for product time-to-market, to reduce part count, part cost and assembly time and improve quality and reliability seems to increase almost daily. New Computer Aided Engineering (CAE) tools to help the engineering, design and manufacturing team accomplish these goals also seem to be introduced at a phenomenal rate. Considering the facts that CAE technology is advancing at such a rapid rate and that the global marketplace pressures are also expanding at a rapid rate, engineering educators today face the challenges of preparing their students for that global marketplace, integrating the new CAE tools and concurrent engineering into the curriculum and maintaining the integrity of the basic engineering and engineering technology programs. This paper describes the efforts in the Department of Engineering Technology at Western Washington University to integrate design, concurrent engineering and microcomputer applications into the manufacturing and plastics engineering technology programs.

In their freshman year, students complete two courses in engineering graphics where solid modeling, traditional Computer Aided Design and Drafting (CAD), and sketching have largely replaced manual drafting courses In their sophomore year, all students are required to complete a microcomputer based course in CAE tools In that course, students learn basic tools such as operating systems (DOS®, Windows®, and UNIX®), spreadsheet programs (Excel®), symbolic equation solvers (Mathcad®) and technical document production (Word®) Other sophomore courses, such as Materials Science, Statics and Strength of Materials, require students to use those tools for homework and projects. In the junior year, students are introduced to applied finite element analysis (FEA) in machine design and Computer Numerical Control (CNC) machining in their CNC course In the senior year, students complete projects with all these tools and use more advanced FEA C-Mold®, a program to model injection molding processes, is also introduced and used in the senior year Students complete concurrent engineering design projects in the sophomore through senior year All the CAE tools at Western are microcomputer based (“486” based).
Engineering Analysis and Simulation Using Visual Basic
Authors: Ng Kelvin , Presz Walter M. , Khosrowjerdi M.
Published: March 2021

Internal gas flow systems are often used in engineering applications to transfer or absorb energy, or transport materials. Most commercial systems are designed or retrofitted with “off the shelf” components. When pre-built components are selected, post design calculations and experimental tests are required for system optimizations. These calculations are complex and require numerous iterations. The objective of this project was to develop and verify a computerized scheme for optimizing fluid systems. This computerized scheme dramatically reduces the analysis time required, and increases analytical accuracy for system operating characteristics. The software allows a user to interactively create parametric models for various systems, then solve it for system performance characteristics. Also the user may perform sensitivity analysis in order to optimize the model for operating efficiency. Using Visual BASIC, separate analytical modules were developed to analyze individual flow components. Each module consists of one or more input forms which communicates with a main module. The main module uses these solutions to solve system operating points.
Principal Elements of Solid Modeling
Authors: Pao Y. C.
Published: March 2021

Three-dimensional basic solids generated by linear sweeping of primitives are presented to demonstrate that when stored as a script file, every detail involved in the linear sweep can then be listed. A linearly tapered fillet serves as an example to depict the boolean operations. For better visibility of a solid, splitting the display screen into multiple windows for showing various projects of the solid when viewed from different angles, the hidden-line technique, and changing the location of light source(s) in addition to an ambient light are also described.
Design and Analysis of a Mobile Robotic Wheel by Nonlinear Programming
Authors: Jha Prabhudutt
Published: March 2021

This paper deals with optimal design of a triangular frame mobile robotic wheel. The rollers are mounted around the periphery of wheels. From Lagrangian kinematics the torque equation and constraints are developed. The reduced gradient method of nonlinear programming is used to minimize the torque under the constraints. The alternate designs produces optimal design for angular velocity and acceleration. The whole approach is presented through an example.
Concept, Development and Implementation of DAMOS-C: The Object Oriented Approach to Multibody Systems
Authors: Daberkow Andreas , Schiehlen Werner
Published: March 2021

The increasing use of computer aided design (CAD) and multibody dynamics software in engineering design and analysis requires an efficient communication management between different codes. As product cycle times are shrinking and companies are under competitive pressure, an automation of the model data exchange between CAD and multibody dynamics is urgently demanded.

In this paper the concept, development and implementation of the independent, object-oriented multibody modeling kernel DAMOS-C is presented. According to the different multibody formalisms, computer codes and applications in vehicle, machine and robot dynamics a general description and organization of multibody system data is introduced. A general data model is developed to fulfill the needs of a modular simulation system based upon numerical and symbolical formalisms. With respect to existing CAD interfaces, different solid model construction methods and visualization procedures, multi-body system classes and methods are implemented in the multibody modeling kernel. The extreme versatility of this modeling kernel is shown by an integration in a commercially available CAD-system and by application to a conversion tool which processes input data for different multibody software codes.
A Method for Early Manufacturability Evaluation of Proposed Tolerance Plans for Thin-Walled Parts
Authors: Fathailall Ajit K. , Dixon John R.
Published: March 2021

This paper describes a method for evaluating proposed part tolerancing plans for injected molded, die cast, and stamped parts from a manufacturability perspective. Before exact dimensions are established (the configuration stage), a qualitative evaluation of proposed designs enables designers to identify features and tolerance specifications that may be difficult to achieve. After dimensions are established (parametric stage), assigned tolerance values are evaluated considering materials and associated configuration issues. Examples in the use of the method are included.
The Use of the Independence Design Axiom As an Enhancement to QFD
Authors: Bascaran Eduardo , Tellez Carlos
Published: March 2021

In recent years, engineering design has been recognized as one of the areas with greatest potential for overall improvements on the life cycle cost of consumer products. Two key ideas that are recognized in modern design practice are the creative implementation of basic functional requirements as well as the incorporation of consumer perceptions of need in the initial stages of the design process.

The Quality Function Deployment Method, QFD, has been used by many companies to incorporate consumer needs and preferences in the design of products and services. The QFD method is based on the paradigm that engineering products are coupled by nature. This idea is not unique to QFD. What differentiates the method is the notion that coupling is desirable. Specifically, this notion seems to be in contrast with the bases of the theory of Axiomatic Design. According to this theory, one of the driving forces of a design process is the elimination of coupling conditions between product functions and their corresponding implementations.

In this paper we address the apparent inconsistency between QFD and Axiomatic Design. We specifically concentrate on the application of the Independence Design Axiom as an enhancement to the QFD process. A brief description of both methods is presented first, followed by a step by step description of how both concepts can be used in harmony to improve the conceptual product design process.
Transforming Design Practice in a Small Manufacturing Enterprise
Authors: Radcliffe David F. , Harrison Peter
Published: March 2021

Small manufacturing enterprises comprise the bulk of manufacturing industry yet little account is taken of such firms in the literature on design theory and methodology. This paper presents an account of the in-house design style of a small, innovative company that designed and manufactures an award winning range of hydraulic cylinders. With assistance from the University of Queensland this company is adopting more formal design methods as part of a major new product development project over three years. The company’s experience of learning about and adopting quality function deployment (QFD) concepts and procedures is presented as an example of this process. The transition to new methods has been accompanied by changes in personnel and responsibilities. Based on this shared experience, the process of transforming design practice in the company is not characterised by a linear model of technology transfer. Rather it is best described by an action research model of cyclic learning and mutual discovery focused on practice, research and teaching leading to a set of concurrent outcomes for each participant.
Diagnostic Modeling and Diagnosability Evaluation of Mechanical Systems
Authors: Clark Garrett E. , Paasch Robert K.
Published: March 2021

Consideration of diagnosability in product design promises to increase product quality by reducing maintenance time without increasing cost or decreasing reliability. Methods for investigating the diagnosability of mechanical and electro-mechanical systems are described and are applied to the Bleed Air Control System (BACS) on the Boeing 747-400. The BACS is described and a diagnostic model is developed using information from the system Failure Modes and Effects Analysis. Emphasis is placed on the relationships between the system’s functions and its components. Two metrics for the evaluation of system diagnosability and two metrics for the evaluation of component diagnosability are defined. These metrics emphasize diagnostic ambiguity and are combined with the probability of different system failures to weight the affects of each failure. Three modified systems are produced by reassigning functions from one component to another. The resulting affects on the system and component diagnosability are evaluated. We show that by changing these relationships system diagnosability can be improved without adding sensors or other components.
A Support Tool for Constraint Processes in Embodiment Design
Authors: Thornton Anna C.
Published: March 2021

Embodiment design of mechanical systems can be viewed as a process of constraint specification and satisfaction of highly coupled equality and inequality constraints. A set of methods and tools developed to support this process are described in this paper. These methods include a product model capable of supporting the necessary design information, the use of generic components to rapidly specify design constraints, and SANCS (Simulated Annealing Network Constraint Satisfier), an algorithm developed to automate the satisfaction of large sets of design constraints.
Re-Engineering Design Education: Design Process and Learning Activities
Authors: Sorensen Carl D. , Todd Robert H. , Magleby Spencer P. , Parkinson Alan R.
Published: March 2021

To achieve superior product and process designs with “typical” engineering students requires careful attention to the design process that is taught and the teaching methods to be followed. The Integrated Product and Process Design (or Capstone) program at BYU has applied both. The Capstone program has been in operation for four years, with over 300 students having been through the program, and over 60 projects sponsored by industry.

The design process taught in Capstone starts with a rapid cycle through to preliminary concept selection. The process is then repeated, starting with the development of a functional specification, which is followed by formalized concept generation and selection methods, layout and detailed part design using solid modelers, experimental and analytical methods for answering design questions, simultaneous part and manufacturing process design, prototype, and production sample. This design process includes a high degree of concurrent involvement from each of the disciplines on the project team.

Non-traditional teaching methods that have proven useful in the class include the use of an industrial paradigm for the educational experience, the use of faculty coaches to mentor the student teams, the use of projects sponsored by industry with regular feedback from the industrial customer, just-in-time education so that students can see immediate application of what is taught, the use of skits and role-playing to teach interpersonal skills, and specific activities that help in the production of project deliverables.

The use of this design process and these teaching methods has led to successful design education. Students, faculty, and industrial customers have all been pleased with the success of the Capstone program in producing superior design engineers.
Integration Analysis of Product Decompositions
Authors: Pimmler Thomas U. , Eppinger Steven D.
Published: March 2021

This paper describes a methodology for the analysis of product design decompositions. The technique is useful for developing an understanding of the “system engineering” needs which arise because of complex interactions between components of a design. This information can be used to define the product architecture and to organize the development teams. The method involves three steps: 1) decomposition of the system into elements, 2) documentation of the interactions between the elements, and 3) clustering the elements into architectural and team chunks. By using this approach, development teams can better understand the complex interactions within the system, thus simplifying the development process for large and complex projects.
Producibility Analysis Using Metrics Based on Physical Models
Authors: Subramaniam Bala L. , Ulrich Karl T.
Published: March 2021

This paper presents an approach to evaluating producibility intended to enhance the ability of engineers to quickly design low-cost and high-quality parts. We divide all production processes into two categories: trajectory-dominated processes in which a generic tool is moved in a trajectory to form the part-shape and process-physics-dominated processes in which shaped tools are used to form similarly shaped parts. We focus on process-physics-dominated processes and on producibility problems that arise because of part shape. We argue that, for these processes, the currently popular approach of representing parts as collections of geometric features is inappropriate for evaluating producibility. We propose an alternative approach and representation. Our approach consists of first identifying the different failure modes of the process and then defining producibility metrics corresponding to the likelihood of encountering each failure mode. This set of metrics is used to represent the degree to which a part is easily manufactured. Finally, we demonstrate this approach by developing a set of metrics for evaluating the producibility of aluminum extrusions. We use extrusions from the Boeing 777 to validate the metrics.
The Technology of Language and How Advances Will Affect Mechanical Design
Authors: Povilus David S. , Conrad Jerome C.
Published: March 2021

The Importance of Language To Mechanical Design

Increasingly, an information-centric view of the design process is being offered as the key to improvements in mechanical engineering. In such views, the focus on the importance, requirements, and problems of language is clear.
Design Actor-Based Representation of Iterative Design Process for Embodiment Design
Authors: Ahn Jeong-Soo , Park Kyihwan , Crawford Richard H.
Published: March 2021

Design activities consists not only of product design, but also of development of the process by which the product will be designed. However, development and documentation of computational design processes are largely unsupported by commercial CAD systems. This paper proposes a new computational architecture for procedural representation of embodiment design processes. A design actor is defined as an independent computational unit of the design process. The proposed architecture models a design process as a sequence of design tasks by representing individual parameters and tasks as design actors, and the sequence of design tasks as a network of design actors assembled according to their functional dependencies. The use of design actors promotes modularity in representing design problems and solution processes. Iterative design processes can be represented since the architecture provides explicit feedforward and feedback information exchange between design actors. The paper describes an object-oriented implementation of the design actor architecture, and demonstrates the approach with an example design of an air-core solenoid in an optical disk drive.
On Representation and Interpolation of Line-Segments for Computer Aided Geometric Design
Authors: Ge Q. J. , Ravani B.
Published: March 2021

In this paper, three new representations of a line-segment are introduced that combine Plücker line coordinates with specifications of length and location of a line-segment. For each of the three line-segment representations, a right conoidal interpolant of two arbitrarily disposed line-segments is developed. These interpolants are then combined with deCasteljau-like algorithms for generating ruled surfaces. The results can be extended to develop new algorithms for computer aided geometric design of geometric shapes based on line geometry.
Optimizing Tolerance Allocation Based on Manufacturing Cost and Quality Loss
Authors: Krishnaswami Mukund , Mayne R. W.
Published: March 2021

This paper describes a procedure for optimizing the allocation of tolerances considering manufacturing cost and product quality in a constrained optimization process. The procedure can utilize various existing models for relating manufacturing costs to part tolerances. It also includes a relationship between part tolerances and assembly tolerance to provide a quantitative measure of product quality using the Taguchi concept of quality loss. The two cost relationships are combined in a formulation which is convenient for solving the optimal tolerance allocation problem by nonlinear programming methods. Numerical optimization can then be directly applied to balance manufacturing cost and product quality allowing trade-offs to be explored.
A Kinematic Based Analysis for Tolerances Within Mechanical Assemblies
Authors: Ogot M. M. , Gilmore B. J.
Published: March 2021

Variation of dimensions within assemblies can unexpectedly displace parts from their intended location and therefore degrade the assembly’s performance. This paper presents a design tool based on the principles of kinematics to analyze nonlinear tolerance stackup, increase the reliability of the assembly without decreasing tolerances and where necessary, judiciously allocate tolerances such that the critical parts fit relative to each other with the specified precision.

Through an analytical sensitivity analysis, the procedure outlined in this paper alters the orientations of the parts to yield an assembly with the highest positional reliability. If the desired level of reliability is not met by the minimum sensitivity approach, a tolerance allocation method incorporating the above sensitivity analysis and the cost of manufacturing each dimension as a function of tolerance is applied. In addition, this approach allows the individual tolerances within the assembly to assume any distribution. The method shown by this paper allows the design engineer to consider manufacturing effects and provides an analytical basis to evaluate design function.
Form Feature Recognition Using Base Volume Decomposition
Authors: Coles James K. , Crawford Richard H. , Wood Kristin L.
Published: March 2021

A new feature recognition method is presented that generates volumetric feature representations from conventional boundary representations of mechanical parts. Recognition is accomplished by decomposing the known total feature volume of a part into a set of smaller volumes through analytic face extension. The decomposed volumes are combined to generate an initial set of features. Alternative sets of features are generated by maintaining and evaluating information on intersections of the initial feature set. The capabilities of the method are demonstrated through both a hypothetical and a real world design example. The method’s ability to locate features despite interactions with other features, and its ability to generate alternative sets of features, distinguishes it from existing recognition techniques.
Constrained Reconstruction of Parametric Surfaces for Reverse Engineering
Authors: Puntambekar Nirant V. , Jablokow Andrei G.
Published: March 2021

This paper presents techniques for reverse engineering of objects containing faces with multiple loops (faces with holes, slots, etc.) wherein these internal loops are specified as constraints on the underlying surface. Non Uniform Rational B-spline (NURBS) surfaces are used for the representation of the faces with the constrained regions specified analytically. The algorithm for fitting of NURBS surfaces to a set of data points is first discussed and then the conditions necessary for joining two patches with the desired continuity (either C0, G1 or C1) are developed. Finally the concepts developed are illustrated with three examples. This paper thus brings together the initial results in the development of a constraints based system for reverse engineering of multiple loop faces in a B-Rep based modeler context.
Surface Approximation in Reverse Engineering
Authors: Mukherjee S. , Gurumoorthy B.
Published: March 2021

This paper describes the steps involved in generating a surface which interpolates a given set of input points. The approach presented departs from those reported in literature in two significant ways. The parametric values are assigned independently and not averaged over the row/column. This helps to localize changes during error optimization. The measure used for the interpolation error is the shortest distance between the input points and the surface and not the distance between the input point and its corresponding point as used in literature. This it is believed, is more intuitive physically and has been shown to result in a better interpolation.
Face Identification of Objects in Wireframe Representation
Authors: Yang D. C. H. , Lin Yu-Long
Published: March 2021

In this paper a method for the face identification of wireframe models has been proposed. The method is based on a new definition of the connectivity matrix. The main idea of this definition is that each element of the connectivity matrix carries the information of the number of faces adjacent to the element. A face identification algorithm is subsequently developed. The algorithm is based on graph theory, and two anomalous detection methods, namely, a remaining connectivity matrix method and an inner product method. The inner product method is used for identifying cross-intersected pseudo interior faces, and the remaining connectivity matrix method, for other types of pseudo interior faces. The results show that this method is systematic and comprehensive.