bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic Algorithms As an Approach to Configuration and Topology Design
Authors: Chapman Colin D. , Saitou Kazuhiro , Jakiela Mark J.
Published: March 2021

The Genetic Algorithm, a search and optimization technique based on the theory of natural selection, is applied to problems of structural topology optimization. Given a structure’s boundary conditions and maximum allowable design domain, a discretized design representation is created. Populations of genetic algorithm “chromosomes” are then mapped into the design representation, creating potentially optimal structure topologies. Utilizing genetics-based operators such as crossover and mutation, generations of increasingly-desirable structure topologies are created.

In this paper, the use of the genetic algorithm (GA) in structural topology optimization is presented. An overview of the genetic algorithm will describe the genetics-based representations and operators used in a typical genetic algorithm search. After defining topology optimization and its relation to the broader area of structural optimization, a review of previous research in GA-based and non-GA-based structural optimization is provided. The design representations, and methods for mapping genetic algorithm “chromosomes” into structure topology representations, are then detailed. Several examples of genetic algorithm-based structural topology optimization are provided: we address the optimization of beam cross-section topologies and cantilevered plate topologies, and we also investigate efficient techniques for using finite element analysis in a genetic algorithm-based search. Finally, a description of potential future work in genetic algorithm-based structural topology optimization is offered.
First-Order Necessary Conditions for Robust Optimality
Authors: Cagan Jonathan , Williams Brian C.
Published: March 2021

The first-order necessary conditions of optimality are extended to include information about robust design — cost insensitivity to model inaccuracies and changes in design specification, as well as the manufacturing tolerances treated in more traditional approaches. In these extended conditions, the Lagrangian is formulated as a tradeoff between cost and cost variability, where variability is measured as the flatness and curvature of the objective relative to local variations in design variables and constraints. During optimization these conditions allow cost and robustness to be considered simultaneously at each iteration.
Manus Colobi: Preliminary Results on the Design of a Mechanical Hand for Industrial Applications
Authors: Gosselin Clément M. , Montambault Serge , Gosselin Claude J.
Published: March 2021

This paper presents the kinematic and mechanical design of Manus Colobi, a robotic mechanical hand developed for industrial applications. A review of the design constraints and a general discussion of the objective tasks to be performed by the hand are first presented. This leads to a description of the kinematic properties and the mechanical design of the hand. Applications envisioned for the hand are robust industrial tasks involving rather large forces which justifies the new design presented here.
On Singularities of Planar Parallel Manipulators
Authors: Mohammadi Daniali H. R. , Zsombor-Murray P. J. , Angeles Jorge
Published: March 2021

The singularities of the Jacobian matrices of two manipulator with three degrees of freedom are analyzed. One is a planar 3-legged manipulator; the other, a planar double-triangular manipulator. A general classification of parallel-manipulator singularities into three groups is described. The classification scheme relies on the properties of the Jacobian matrices of the manipulator. Finally, the three types of singularity are identified for the two manipulators.
Multiobjective Optimization of Fiber Composite Shells for Maximum Buckling Load and Imperfection Tolerance
Authors: Zimmermann Rolf H.
Published: March 2021

The performance of thin-walled structures, which are endangered by buckling, is often strongly influenced by geometrical imperfections. It is impossible to know in advance the imperfections, which will be present in the real structure. Nevertheless, their influence has to be taken into account already at the design process. Attempts to identify characteristic imperfections due to specific manufacturing processes overcome this difficulty only partly, as they do not consider imperfections coming into existence after fabrication. The remedy is, to build imperfection tolerant structures. For that purpose, a simple means to measure imperfection tolerance is defined, and a multiobjective optimization formulation is proposed to design fiber composite shell structures, which simultaneously exhibit high imperfection tolerance and high buckling load. By example of axially compressed CFRP cylindrical shells first computational and experimental results are given to demonstrate the feasibility of the concept, and to identify needs for further research.
Integration of Parametric Modeling and Structural Analysis for Optimum Design
Authors: Rasmussen John , Lund Erik , Olhoff Niels
Published: March 2021

The ideas and methods behind a new system, ODESSY, for optimum mechanical engineering design are described. The motivation behind this work is found in the current trend toward unification of engineering design tools which were previously developed and used separately, namely geometric modeling in the form of CAD systems, and mechanical analysis in the form of finite element programs. The united capabilities of these techniques allow for a major step forward in Mechanical Engineering Design, i.e. from tools aimed at analysis to tools aimed directly at synthesis.
Layout of Plate Structures for Improved Dynamic Response Using a Homogenization Method
Authors: Soto Ciro A. , Diaz Alejandro R.
Published: March 2021

A model to compute average properties for Mindlin plates of rapidly varying thickness was introduced in [SOT93]. The model was designed to be of use in computations of the optimum shape and layout of plates using the technique introduced by Bendsøe and Kikuchi [BEN88]. In this paper we discuss the utilization of the model to determine the optimum layout of plate structures that maximizes a function of the structure’s natural frequencies. A simply supported square plate is used to illustrate the problem of optimization in the presence of repeated natural frequencies. An automotive application is presented to illustrate the usefulness in design practice.
A Continuous Force Model for Elastic-Plastic Impact of Solids
Authors: Trabia Mohamed B.
Published: March 2021

A model for elastic-plastic impact analysis of solids is presented. This model is valid for the cases when plasticity accounts for the absorption of energy during impact. It is assumed that impact forces follow continuous Hertz contact force model. The model depends on a new mechanism for energy absorption in the impacted solids. The method yields the relative velocity of impact needed to initiate permanent deformation, coefficient of restitution, and impact time. As an example, impact between spheres is considered. Comparison between analytical and experimental results is included.
Adaptive Refinement for 3-D Finite Element Analysis
Authors: Muthukrishnan S. N. , Namblar R. V. , Lawrence K. L.
Published: March 2021

A simple strategy to adaptively refine three dimensional tetrahedral meshes has been implemented. A method of refinement for both plane faced and curve faced elements is presented in this paper. Examples are presented in which the rcmeshing is based on a refinement ratio determined from an a-posteriori error indicator obtained from the finite element solution of the problem. The resulting finite element meshes have a smooth gradient in element size. Example meshes are included to show the adaptive nature of the remesher when applied over several solution cycles.
Modeling and Analysis Method for a Compound Mechanism With a Cam and Linkages
Authors: Shiohata Koki , Ozawa Hiroshi , Utsmi Itsunori , Kobayashi Mitsuru , Fijisawa Fumio
Published: March 2021

In the dynamic analysis of a compound mechanism with a cam and linkages, cam contour equations are often used to produce solutions in polar coordinates. This requires calculating higher-order equations corresponding to the complicated non-cycloidal cam contours. In this paper, a new method is proposed to analyze the behavior of a cam with arc, straight and corner contours. This method is characterized by converting cam behavior into linkage behavior, that is, a cam is modeled by a linkage. This method can solve for the cam and linkage parts of a compound mechanism simultaneously using the conventional linkage analysis. The method is successfully applied to a numerical analysis of the dynamic behavior of the compound mechanism with a cam and linkages in an automatic teller machine. Further, the accuracy of calculation of the mechanism’s dynamic behavior is discussed for two analytical models, the series model and the parallel model.
A Sequential Approximation Method for Structural Optimization Using Logarithmic Barriers
Authors: Kumar Ashok V. , Gossard David C.
Published: March 2021

A sequential approximation technique for non-linear programming is presented here that is particularly suited for problems in engineering design and structural optimization, where the number of variables are very large and function and sensitivity evaluations are computationally expensive. A sequence of sub-problems are iteratively generated using a linear approximation for the objective function and setting move limits on the variables using a barrier method. These sub-problems are strictly convex. Computation per iteration is significantly reduced by not solving the sub-problems exactly. Instead at each iteration, a few Newton-steps are taken for the sub-problem. A criteria for moving the move limit, is described that reduces or eliminates stepsize reduction during line search. The method was found to perform well for unconstrained and linearly constrained optimization problems. It requires very few function evaluations, does not require the hessian of the objective function and evaluates its gradient only once per iteration.
Topology Optimization of 3D Trusses With Cost of Supports
Authors: Pedersen Pauli
Published: March 2021

The basic assumption for the present paper is the single load condition. In other aspects the stated problem is rather general and the important issue of local stability is taken into account. Even for this problem we can always find a statically determined topology that will minimize the cost of the structure.

The constraints of the optimization problem are allowable stresses, with the allowable compressive stresses being design-dependent. Supports are treated as design variables, and cost of a possible support can be given within the same generality as cost of truss members. The formulation is given in terms of bar forces and a modified Simplex technique is developed for the numerical solution.
Smooth Surface Fitting and Finite Element Mesh Generation for Irregularly Distributed Data Points
Authors: Chen Yih-Jen D.
Published: March 2021

This paper presents two computational methods for geometric modeling of curved surfaces represented by irregularly distributed data points. The study emphasizes irregularly distributed data points since this represents the most general case in geometric data interpretation. The first method is a direct mesh mapping procedure, which projects an relatively regular mesh to the complicated real surface. The second method is a surface fitting technique that reconstructs the mathematical surface model using piecewise bi-cubic parametric functions or B-spline functions. This data reconstruction method uses a normal-distance least-squares concept to generate the best fit. Recursive subdivision algorithm and quad tree data structure are applied to optimize the number of patches needed within the desired precision and thus minimize the computing time in the further processing of the surface model. A computer program based on the two computational methods in surface modeling has been developed and demonstrated by its engineering application. Its development provides an automated tool for design engineers and structure analysts to interpret and model complex surfaces derived from data points.
Reconstruction of B-rep Solid Models From Finite Element Meshes for Design Automation
Authors: Jablokow Andrei G. , Abraham Isaac
Published: March 2021

This paper presents the integration of Finite Element (FE) techniques with B-rep solid modeling. Algorithms for constructing B-rep solid models from a finite element meshes are presented. The finite element mesh data, which consists of node coordinates and connectivity information, is read in from any standard finite element analysis package (currently SDRC IDEAS and MSC/XL) and then processed to construct a polyhedral non-manifold B-rep solid model of the geometry. Since the finite element mesh of a solid object is essentially a non-manifold object, existing geometric modeling data structures based on two-manifold topologies cannot represent it directly. In this work the non-manifold radial-edge data structure is used for the internal representation of the finite element mesh. The mesh is then processed using non-manifold topology operators to eliminate internal nodes and elements to arrive at the solid model that is a polyhedral boundary representation. The results are useful for design automation through the integration of CAD with finite element analysis, shape optimization, as well as the manufacturing of geometry stored as a finite element mesh.
Motion Interpolation and Mechanism Synthesis
Authors: Ge Q. J. , Ravani B.
Published: March 2021

This paper studies planar motion approximation problems from a computational geometric perspective and develop a computational geometric structure that can be used for mechanical motion synthesis. This allows for development of computational algorithms and software systems to support the mechanical design activity. The approach uses an orientable kinematic mapping to transform the mechanical design problem into a curve design problem in the space of the mapping. The curve design problem for synthesis of an analytic motion is carried out by Hermite interpolation. In case of a mechanical linkage, however, the Hermite interpolation is combined with a first-order curve fitting procedure for synthesizing the motion.
Kinematic Synthesis of an RS-SRR-SS Adjustable Spatial Motion Generator for Three Alternate Tasks
Authors: Yao Jin , Xu Liju , Fan Shou-wen
Published: March 2021

A method is presented for kinematical synthesis of an RS-SRR-SS adjustable spatial motion generator for three alternate tasks. Three separate systems of synthesis equations to exactly generate the first and the last positions for each task are obtained for the R-S by co-plane and constant distance conditions, for the S-R-R by co-plane, constant distance conditions and inversion theory, and for S-S by constant distance condition. Based on these equations, mathematical model for approximately generating the intermediate positions for each task is formulated. This method is characterized by reduction of the unknowns and equations in both exact and approximate syntheses. As a result, computing work is to be decreased obviously.
Computational Efficiency of First and Second Order Sensitivity Analysis Methods for Dynamic Systems
Authors: Cao Qiushi , Krishnaswami Prakash
Published: March 2021

First and second order design sensitivity information have become very popular in engineering design, due to the recent development of appropriate methodology and computer technology. This paper presents an empirical study of the computing effort required for computing first and second order design sensitivity information for constrained dynamic mechanical systems and compares the relative efficiency of analytical and finite difference method. Four typical examples have been solved, with the computing time being recorded in each case. The time comparison results indicate that it is generally much more efficient to produce first order design sensitivity information by a direct analytical method than by finite differencing. For second order design sensitivity analysis, the results indicate that a purely analytical solution is usually more efficient than a pure finite difference solution. However, a hybrid scheme appears to be very competitive in terms of computational efficiency.
Optimal Design of Composite Lightweight Rollers
Authors: Bellendir K. , Eschenauer Hans A.
Published: March 2021

A well-aimed layout of fibre-reinforced lightweight rollers does not only require an efficient structural analysis procedure but also the application of structural optimization methods. Therefore, an analytical procedure is introduced for the calculation of the static behaviour of cylindrical shells subject to axisymmetric and/or nonaxisymmetric loads. In the scope of this procedure, arbitrary, unsymmetrical laminates as well as various boundary conditions will be considered. Basis is the shell theory by Flügge enhanced by anisotropic constitutive equations (material law) in the scope of the classical laminate theory. By means of mathematical optimization procedures we then determine optimal lightweight rollers, using different design and evaluation models. For that purpose, coated and uncoated roller constructions as well as hybrid types made of CFRP/GFRP will be applied. Concluding, we will discuss possible improvements and advantages of anisotropic lightweight rollers in contrast to isotropic ones made of steel or aluminium.
Vectorial Tolerancing for All Types of Surfaces
Authors: Martinsen Kristian
Published: March 2021

This article is a systematisation of Vectorial Tolerancing in order to show how it can be adapted to all kinds of surfaces on a workpiece. Vectorial Tolerancing provides a clear distinction between the different geometrical features size, form, location, and orientation for each surface. In Vectorial Tolerancing are location and orientation of a surface described with vectors in a Workpiece Co-ordinate System. The tolerance on the location and orientation vectors is described in the Tolerance Co-ordinate System. Only the fixed degrees of freedom are given tolerances on a surface.
An Object-Oriented Formalism for Geometric Reasoning in Engineering Design and Manufacture
Authors: Navaneethakrishnan Ravisrinivas , Wood Kristin L. , Crawford Richard H.
Published: March 2021

Geometry is a language for representing and communicating mechanical design information. To enhance the integration of design and manufacturing tasks, a representation of product geometry at appropriate levels of abstraction for geometric reasoning is necessary. In addition, a mechanism to perform reasoning with the representation is needed. This paper describes a computational formalism for representing and manipulating geometry at different abstraction levels. Geometry is abstracted in terms of form features. Spatial relationships between features, which are important components for geometric reasoning, are represented using a modification of a previously developed technique — the intermediate geometry language (IGL). To enable geometric reasoning, information abstracted using features and the IGL is transformed into a data model based on object-oriented modeling technology. An object algebra is defined to query the data model for information.
Application of Multidisciplinary Design Optimization to the Power Stage Design of a Power Converter
Authors: Kott Gregory , Gabriele Gary A. , Korngold Jacob
Published: March 2021

This paper describes the application of multidisciplinary design optimization to the power stage design of a power converter. The decomposition of the power stage design into an electrical and a loss subsystem is developed. The Sequential Global Approximation method is the non-hierarchic algorithm used to optimize the power stage design problem. Results of the non-hierarchic formulation compared to the non-decomposed formulation show a decrease of 63 percent in total system iterations required to converge to the optimal solution. Local and global move limits of 28 percent were found to provide the best performance for this problem.

The successful implementation and results of applying multidisciplinary design optimization to power stage design allows the extension of the research to incorporate other disciplines. Our goal is to include all disciplines to completely model the design of a power converter. The details of power stage design problem formulation are provided to be used as a test problem in multidisciplinary design optimization research.
Application of Stochastic Optimization Techniques at the Example of Ceramic Turbine Disks
Authors: Eschenauer Hans A. , Vietor Thomas
Published: March 2021

In comparison to metallic materials, ceramic materials are very brittle which has made a wide use of them difficult up to now. For this reason, stochastic failure criteria, which differ considerably from those of ductile materials, have to be formulated and calculated mathematically. Because of high specific elasticity and stiffness properties, the ceramics are suitable for the layout of rotating components with a high rotating velocity. In order to find the optimal layout of a component made of ceramic materials, a stochastic optimization problem has to be defined and solved.

A ceramic turbine disk has been chosen to demonstrate the shape optimization and the application of the stochastic optimization. By means of the functional-efficient boundaries and the associated optimal contours of the component conventional ductile materials are compared with ceramics for this application example. Herewith, the range of application of the materials examined can be determined.
Design Improvement by Simulation of Biological Growth
Authors: Mattheck Claus G. , Baumgartner Andreas , Kriechbaum Ralph G. , Walther Frank K.
Published: March 2021

Natural structures have been analyzed and investigated over many years for impulses and benefits that could possibly be applied to man-made technical structures. With today’s possibilities of computer-aided calculations, methods have been developed to improve the primitive research into nature by providing scientists with the tool of simulation for much preciser statements about the phenomena observed in the open.

K. Metzger, a German forester and author, reported on the existence of an even stress distribution in biological structures as early as 1893 (Metzger, 1893). For stems of spruce he observed that there is a definite relationship between the growth of stems and the mechanical loads which act on them. Metzger’s experience was adopted by a team of scientists at Kernforschungszentrum Karlsruhe GmbH. His observations have been providing the basis of extensive computerized simulations assisted by the finite-element method (FEM). Some of these calculations are discussed in this paper to prove and corroborate the theses given below.
Optimization of Helical Compression and Tension Springs
Authors: Metwalli Sayed M. , Radwan M. Alaa , Elmeligy Abdel Aziz M.
Published: March 2021

The primary objective of spring design is to obtain a spring which will do the required job and at the same time be the most economical for a given application. This means that the spring must fit into the available space and has a satisfactory life in service. The optimum springs would then have minimum weight, minimum length or minimum space. Various optimum values of wire diameter and spring index are obtained. These are evaluated in a closed form or utilizing iterative search techniques. The problem is formulated with and without the variation of the maximum shear stress with the wire diameter. The optimal parameters are also normalized and plotted.
Sculptured Surface Model Synthesis Based on Functional Design Constraints
Authors: Oliver James H. , Theruvakattil Philip C.
Published: March 2021

A technique is presented for the synthesis of sculptured surface models subject to several functional design constraints. A design environment is specified as a collection of polyhedral models which represent components in the vicinity of the design surface, or regions which the surface should avoid. The primary functional constraint is formulated as a proximity penalty function such that the design surface is induced to avoid a tolerance envelope around each component. In addition, a constraint based on surface area is formulated to counteract the expansion effect of the proximity constraint. Secondary design constraints are formulated to maintain consistent surface topology, and exploit part symmetry. Surface synthesis is thus formulated as an optimization problem and solved via simulated annealing. Several example applications are presented to demonstrate the capabilities of the technique.
A Non-Linear Machining Process Planner for Concurrent Mechanical Design
Authors: Ochiai Taro , Hoeltzel David A.
Published: March 2021

The performance of process planning systems is becoming increasingly more important within the context of concurrrent engineering. However, since planning strategies used in typical process planners cannot avoid combinatorial explosion without the appropriate use of domain heuristics, the planners cannot ensure acceptable performance for a more general class of machining problems. Using general non-linear planning techniques, we have developed a planner that attempts to cope with this problem. We establish a formulation for process planning using non-linear planning that enables graph-based conflict resolution. The planning mechanism is implemented using a production system in a computational experiment, and the possibility of generalization of this approach to other types of planning problems is discussed.
The STEP Integration Information Architecture
Authors: Yang Yuhwei
Published: March 2021

Traditionally, when the term “integration” is used to refer to the interoperability of disparate, heterogeneous computer system, it means the ability to exchange digital data between the systems. For the more sophisticated systems designers, “integration” may mean shared, distributed databases or a federated database system. Within the development of the Standard for the Exchange of Product model data (STEP - ISO 10303), “integration” refers to an information architecture composed of conceptual constructs that is independent of implementation considerations.

The Integration Information Architecture of STEP is presented and explained. Instead of a flat representation of abstract (i.e., conceptual) data structures, integration within STEP takes place at four different levels:

1) Intra-Resource integrated.

2) Structural integration of Application Protocols through Integrated Resources.

3) Semantic integration of Application Protocols through Application Interpreted Constructs (AICs)

4) Operational integration through Application Protocols.

Each level of integration and the relationships between the levels is explained.
Tight Integration and Synchronization of Distributed Graphical Applications
Authors: Mueller Wolfgang , Kleinjohann Bernd
Published: March 2021

Most engineering tasks are highly data intensive coping with the increasing complexity of systems. Gigabytes of heterogeneous engineering data have to be managed consistently by a huge array of tools. This necessitates sophisticated integration techniques based on a common database management system in order to decrease the amount of data that have to be exchanged between these tools.

In this paper we present a new approach to distributed design frameworks, integrating graphical as well as text processing tools. Tools may online share the same graphical and logical data synchronized by the event mechanism of an object management system. The synchronization concept is based on a tight integration into an object-oriented object management system and provides means to keep the graphical views of multiple agents consistent. We outline these concepts by the example of an integrated EXPRESS modeling workbench.
Data Fusion for Adaptive Control in Manufacturing: Impact on Engineering Information Models
Authors: Bray Olin H.
Published: March 2021

This paper addresses the impact of data fusion on engineering and manufacturing information systems. Data fusion is the integration and analysis of data from multiple sensors to develop a more accurate understanding of a situation and determine how to respond to it. (Sensor fusion, a related term, has a somewhat different, more implementation oriented focus. The difference between these two concepts is addressed specifically in Section 1.) Although data fusion can be applied in many situations, this paper focuses on its application to manufacturing and how it changes some of the more traditional, less adaptive information models that support the design and manufacturing functions.

Data fusion requires changes, primarily extensions, to these traditional information models. Engineering models normally address geometry, features, and performance characteristics of a part, while manufacturing models address machine tool characteristics and how they interact with the workpiece and operations scheduling. For data fusion and adaptive control, these models must include the dynamic behavior and interactions between the workpiece and the machine tool. In addition, these models must specify how these dynamic behaviors can be seen and interpreted by various types of sensors (e.g. temperature, pressure, and vibration). On a broader level it must also consider how the machine tools and robots interact within a work cell or production line.

The paper consists of four parts. The first section explains what data fusion is and its impact on manufacturing. The second section describes what an information system architecture is and explains the natural language-based information modeling methodology used by this research project. The third section identifies the major design and manufacturing functions, reviews the information models required to support them, and then shows how these models must be extended to support data fusion. The fourth section discusses the future directions of this work.
Structural Integrity System Based on an Object-Oriented Activity- and Product Model
Authors: Lovstad Morten , Syvertsen Tor G.
Published: March 2021

Huge steel or reinforced concrete structures in deep waters support the installations for oil and gas production in the North Sea. Steady operations in a hostile environment require that structural safety and integrity is maintained. For rapid evaluation and assessment of structural integrity in case of modifications or urgency situations, Structural Integrity Systems are established, comprising computational models and structural analysis programs.

A major problem for structural assessment at short notice is to keep the analysis models updated and consistent with the actual state of the physical structure and the loadings. This paper proposes a layered approach for model integration, which enable maintenance of the models at a high level, from which detailed analysis models are derived in a consistent manner.
IBM’s NAVFAC Modeling and Drawing Management System
Authors: Goldschmidt Art
Published: March 2021

NAVFAC is a system of some 4200 workstations to manage U.S. Naval Facilities world-wide. The system applications are from the architectural, cartographic, civil, electrical, and mechanical engineering disciplines.

NAVFAC includes a Modeling and Drawing Management System (MDMS) to manage the tens of thousands disparate files in the environment. IBM responded to the dozens of detailed requirements for MDMS with a custom-built solution which includes several innovations in the areas of configuration management, version control, and globally distributed file management.
Developing and Implementing a Conceptual Composite Materials Design Database
Authors: Rasdorf William J. , Spainhour Lisa K.
Published: March 2021

Researchers and materials engineers require a greater understanding of the problems and solutions that emerge when integrating composite materials data with computer technology so that utilitarian composite materials databases can be developed to effectively and efficiently support analysis and design software. Composite materials constitute a representational challenge due to their composition and use. However, this paper suggests that a conceptual composite material data model and application software interfaces must be developed to support the dissemination and use of composite materials data.

This paper primarily serves to analyze several of the problems facing developers of composite materials databases, evolving from the complexity of the materials themselves and from the current lack of testing and data representation standards. Without a clear understanding of the scope and nature of these problems, there is no possibility of designing concise yet comprehensive composites data models, yet we feel that such an understanding is presently lacking. In addition, an effort is made to present possible solutions to these difficulties being suggested and/or implemented both by the authors and by other researchers in the field. Such an effort provides a firm foundation upon which future research may be based.
Product Standards Data System for Online Document Management
Authors: Piyarali Ali , Galbraith Jeff , Hitsman-Carter Kathy , Mayfield Dave
Published: March 2021

With the current emphasis on simultaneous engineering, organizations are realizing the need to share paper based information in a timely manner to expedite the product development process. The Boeing Company embarked on an ambitious project allowing online access to over 7000 documents spread over 68,000 pages. The Product Standards Data System (PSDS) provides view only copies of all product, process, tooling and design standards through a DOS. UNIX or OS/2 based workstation or an Apple Macintosh. In addition to viewing, the document creation process was automated using a Standardized General Markup Language (SGML) compatible desktop publishing package. The system is based on a tiered architecture and uses a multi-vendor solution to address the required functionality.
Engineering Software Quality Management and ISO 9000
Authors: Schoonmaker Stephen J.
Published: March 2021

This paper presents a management model for “in-house” engineering software. This model expands on a previous publication by the author, and this model is intended to satisfy the requirements of an ISO 9000 registration. ISO 9000 is the quality assurance standard of the International Organization for Standardization. ISO 9000 registration, which includes on-site independent auditing, is becoming a requirement for some businesses operating in the global marketplace. This paper draws on the author’s first-hand experience with this process. The author also urges the ASME to produce guidelines or standards on this material which will allow other mechanical engineers to benefit from his experience.
Engineering Process Management System Product/Process Integration
Authors: Buckley Kurt F.
Published: March 2021

Engineering data management systems (EDMS) offer seamless, integrated, shared-data environments with continuous information flow from product design through product production. Current information technologies and systems engineering methodologies provide the basis for dramatic process improvements and enterprise-wide organizational re-engineering. This paper presents the characteristics of a system being installed, and discusses the benefits afforded to the customer in the area of process improvements. Its emphasis is on data/process integration, a significant feature that allows building extensive metrics and thus enabling continuous process improvement.
Review: An Information Management System for Informal Design Data
Authors: McMahon Chris A. , Pitt David J. , Yang Yong , Sims Williams Jon H.
Published: March 2021

Engineering information management may be divided into formal information management, which involves data modelling, data exchange and transaction handling, and into informal information management, which is concerned with the organisation and delivery of design advice and design parameter data. This paper describes a system, called Review, which has been developed for the management of informal design information from multiple sources. The system uses a hybrid hypertext/database approach to provide for the indexing and viewing of information sources using arbitrary attribute sets, and for the establishment of relationships between information entities using both static and dynamic links in a hypertext framework. Information may be accessed both by query and by browsing along relationships in the hypertext network. The paper presents an overview of the system design, and examples of its application to design advisory systems and documentation.
A Tale of No Cities: Analysis of Premier Lacrosse League Fan Identity and Fanship
Authors: Hakim Samuel D.
Published: March 2021

The present study examined the Premier Lacrosse League (PLL) and fans’ identity and fanship. The PLL boasts a uniqueness many sports fans are unfamiliar with—non-geographically affiliated teams. Using socialization theory, social identity theory, and fan identity, the author sought to better understand the fan qualities of the PLL, especially surrounding athlete importance. A Qualtrics survey was distributed through reddit.com/r/lacrosse and major lacrosse forums with the goal to assess fanship toward favorite players, favorite teams, and PLL media consumption. Statistical analyses revealed that those who have a previously constructed lacrosse fan identity, consume more lacrosse media, and have been following a professional or college lacrosse athlete in the past are more likely to embrace the PLL. In a league where geographical affiliation is currently absent, research suggests that encouraging fan adoption of a favorite player is key to creating fans who begin to feel investment, loyalty, and increased team identity.
Ebola virus may lurk in survivors for many years
Authors: Kupferschmidt Kai
Published: March 2021

Genomic analyses of Guinea patients point to "new paradigm" for how outbreaks start.
Studies chase clues to immune syndrome in kids
Authors: Couzin-Frankel Jennifer
Published: March 2021

Causes and simple diagnostics for MIS-C have been elusive.
Biologists revel in pinpointing active genes in tissue samples
Authors: Pennisi Elizabeth
Published: March 2021

Spatial transcriptomics is "total game changer" for cellular biology, revealing how location affects gene activity.
Tuning electron correlation in magic-angle twisted bilayer graphene using Coulomb screening
Authors: Liu Xiaoxue , Wang Zhi , Watanabe K. , Taniguchi T. , Vafek Oskar , Li J. I. A.
Published: March 2021

Tuning the interactions

Elucidating the nature of the superconducting state in magic-angle twisted bilayer graphene (MATBG) has proven tricky. To study the role of electron-electron correlations in this state, Liu
et al.
placed another graphene bilayer, this one having a conventional arrangement of the graphene sheets, in the immediate vicinity of a sample of MATBG. By varying the carrier density in the conventional bilayer, the researchers controlled the strength of interactions in MATBG. Weakening the interactions strengthened superconductivity, consistent with scenarios in which the electron-phonon coupling competes against Coulomb interactions to stabilize the superconducting phase.

Science
, this issue p.
1261
Record-breaking aerosol levels explained by smoke injection into the stratosphere
Authors: Hirsch Eitan , Koren Ilan
Published: March 2021

Smoke alarm

Intense, widespread bushfires in Australia injected huge amounts of smoke into the stratosphere in 2020. Hirsch and Koren found that this smoke caused record-breaking levels of aerosols over the Southern Hemisphere, as much as that from a moderate volcanic eruption. The severity was caused by a combination of the vigor of the fires and their location at a latitude with a shallow tropopause and within the midlatitude cyclones belt. This aerosol increase caused considerable cooling over oceanic cloud-free areas.

Science
, this issue p.
1269
SARS-CoV-2 transmission without symptoms
Authors: Rasmussen Angela L. , Popescu Saskia V.
Published: March 2021

Symptomless transmission silently drives viral spread and is key to ending the pandemic
Doubling down on our earthly interventions
Under a White Sky: The Nature of the Future
Elizabeth Kolbert
Crown, 2021. 256 pp.
Authors: Caldeira Ken
Published: March 2021

Can we engineer our way out of the planetary problems we've engineered our way into?
A Novel Gene Cluster Is Involved in the Degradation of Lignin-Derived Monoaromatics in Thermus oshimai JL-2
Authors: Chakraborty Joydeep , Suzuki-Minakuchi Chiho , Tomita Takeo , Okada Kazunori , Nojiri Hideaki
Published: March 2021

High-temperature steam treatment of lignocellulosic biomass during the extraction of cellulose and hemicellulose fractions leads to the release of a wide array of lignin-derived aromatics into the natural ecosystem, some of which can have detrimental effects on the environment. Not only will identifying organisms capable of using such aromatics aid in environmental cleanup, but thermostable enzymes, if characterized, can also be used for efficient lignin valorization.
Ilaprazole and Other Novel Prazole-Based Compounds That Bind Tsg101 Inhibit Viral Budding of Herpes Simplex Virus 1 and 2 and Human Immunodeficiency Virus from Cells
Authors: Leis Jonathan , Luan Chi-Hao , Audia James E. , Dunne Sara F. , Heath Carissa M.
Published: March 2021

These results provide the basis for the development of drugs that target enveloped virus budding that can be used ultimately to control multiple virus infections in humans.
Late Eocene post-collisional magmatic rocks from the southern Qiangtang terrane record the melting of pre-collisional enriched lithospheric mantle
Authors: Qi Yue , Wang Qiang , Wei Gang-jian , Zhang Xiu-Zheng , Dan Wei , Hao Lu-Lu , Yang Ya-Nan
Published: March 2021

Diverse rock types and contrasting geochemical compositions of post-collisional mafic rocks across the Tibetan Plateau indicate that the underlying enriched lithospheric mantle is heterogeneous; however, how these enriched mantle sources were formed is still debated. The accreted terranes within the Tibetan Plateau experienced multiple stages of evolution. To track the geochemical characteristics of their associated lithospheric mantle through time, we can use mantle-derived magmas to constrain the mechanism of mantle enrichment. We report zircon U-Pb ages, major and trace element contents, and Sr-Nd isotopic compositions for Early Cretaceous and late Eocene mafic rocks in the southern Qiangtang terrane. The Early Cretaceous Baishagang basalts (107.3 Ma) are characterized by low K2O/Na2O (<1.0) ratios, arc-like trace element patterns, and uniform Sr-Nd isotopic compositions [(87Sr/86Sr)i = 0.7067–0.7073, εNd(t) = −0.4 to −0.2]. We suggest that the Baishagang basalts were derived from partial melting of enriched lithospheric mantle that was metasomatized by subducted Bangong–Nujiang oceanic material. We establish the geochemistry of the pre-collisional enriched lithospheric mantle under the southern Qiangtang terrane by combining our data with those from other Early Cretaceous mafic rocks in the region. The late Eocene (ca. 35 Ma) post-collisional rocks in the southern Qiangtang terrane have low K2O/Na2O (<1.0) ratios, and their major element, trace element, and Sr-Nd isotopic compositions [(87Sr/86Sr)i = 0.7042–0.7072, εNd(t) = −4.5 to +1.5] are similar to those of the Early Cretaceous mafic rocks. Based on the distribution, melting depths, and whole-rock geochemical compositions of the Early Cretaceous and late Eocene mafic rocks, we argue that the primitive late Eocene post-collisional rocks were derived from pre-collisional enriched lithospheric mantle, and the evolved samples were produced by assimilation and fractional crystallization of primary basaltic magma. Asthenosphere upwelling in response to the removal of lithospheric mantle induced the partial melting of enriched lithospheric mantle at ca. 35 Ma.
Supplemental Material: Subduction initiation of the western Proto-Tethys Ocean: New evidence from the Cambrian intra-oceanic forearc ophiolitic mélange in the western Kunlun Orogen, NW Tibetan Plateau
Authors: Zhang Qichao , al. et
Published: March 2021

Detailed petrological and geochemical data.
Primary renal synovial sarcoma presenting with a retroperitoneal bleed
Authors: Huned Daanesh , Kam Juinn Huar , Lee Lui Shiong , Tiwari Raj Vikesh
Published: March 2021

Synovial sarcomas are most commonly localised in extremities, especially in the lower thigh and knee areas. Comprising less than 1% of all malignancies, retroperitoneal synovial sarcoma is very rare with primary synovial sarcoma of the kidney being even more infrequent and difficult to diagnose. We describe a case report of a renal synovial sarcoma in a young adult who was initially managed as a case of Wunderlich’s syndrome secondary to what was believed to be a ruptured renal angiomyolipoma. After biopsy confirmation, the patient was eventually managed with neo-adjuvant chemotherapy followed by a right radical nephrectomy and right hepatectomy. Despite its rarity, synovial sarcoma should be considered as differential diagnosis of a bleeding retroperitoneal soft tissue mass detected in young adults.
Rare, post-periodontitis spondylodiscitis caused byFusobacterium nucleatumin a patient with multiple sclerosis: challenge of diagnosis and treatment
Authors: Pasku Dritan , Shah Siddharth , Aly Ahmed , Quraishi Nasir A
Published: March 2021

Fusobacterium nucleatumis part of the commensal flora of the oral cavity, frequently associated with periodontal infections. We describe the case of a 49-year-old woman, on immunsuppressive therapy for multiple sclerosis, who presented with a 3-month history of debilitating back pain. She had a recent episode of periodontitis, and was under regular dental review. Her MRI scan demonstrated findings suggestive of L2–L3 spondylodiscitis. Her CT-guided biopsy yielded negative cultures and the patient failed two courses of empirical antibiotic treatment. With clinical and radiological disease progression, she underwent a percutaneous disc washout and biopsy, which subsequently grewF. nucleatum. Treatment with clindamycin and metronidazole was commenced orally for 6 weeks. She improved gradually, and at 1 year follow-up was asymptomatic. The diagnosis of spondylodiscitis caused byF. nucleatumis challenging. The perseverance on identification by surgical biopsy, minimally invasive washout and targeted antibiotics are the mainstay of effective treatment.