bluuebunny/crossref_metadata_2025 huggingface dataset:
Hierarchical Selection in Gas Turbine Maintenance Management
Authors: Chen Wei , Allen Janet K. , Mistree Farrokh
Published: March 2021

A concurrent approach to hierarchical selection of design concepts for maintenance management is introduced. The interactions amongst selection problems in maintenance are taken into account concurrently by formulating an entire hierarchy as a single coupled Decision Support Problem (DSP). Using this method it is possible to model interactions among different concepts rather than creating a model in which these decisions are made sequentially, hence this approach can form a basis for concurrent engineering. We illustrate our approach by formulating and solving a gas turbine axial compressor fouling maintenance problem as a coupled selection-selection DSP. The filter for fouling prevention and the washing media for fouling treatment are selected simultaneously while interactions between the two selections are considered. Our focus in this paper is on explaining our approach rather than the results per se.
A General Multi-Body Dynamic Model to Predict the Behavior of Roller Chain Drives at Moderate and High Speeds
Authors: Kim Mahn Shik , Johnson Glen E.
Published: March 2021

An advanced model in which most important factors of the roller chain drive are considered is developed. Most importantly, for the first time the series of elastic collisions and rebounds that occur as the chain links engage the sprocket is modeled here. Equations of motion are derived in a form very efficient for numerical solution by applying Kane’s method. The equations of motion are programmed and used to simulate responses of dynamic roller chain drives.

The dynamic behavior of roller chain drives at moderate and high speeds is studied. Comprehensive observations about the engagement process are presented and discussed. The influence of impact due to collision is investigated. The effects of the center distance and the operation speed on the dynamic behavior of the roller chain are studied, with special attention to the trajectory of the roller chain, the phase between disengagement and engagement, and the transverse vibration.
Abstraction As a Configuration Design Methodology
Authors: Snavely Gary L. , Papalambros Panos Y.
Published: March 2021

Configuration design can be thought of as a process of generating artifacts by assembling pre-defined components. This paper introduces a method for reducing the size of configuration problems by abstracting components to higher levels of abstraction. At higher abstraction levels, less important detail is temporarily ignored, and each component represents a family of lower-level components. Configuration is then performed at the highest level, explicitly enumerating all configurations at that level. Any complete configuration at the highest level is recursively instantiated to lower levels. At the same time, any incomplete configuration at the highest level is eliminated, thereby eliminating all possible lower-level instantiations of that configuration. In this manner, all configurations of components at the lowest level of abstraction are implicitly enumerated.
FRODO: Constraint-Based Object-Modeling for Preliminary Design
Authors: Kolb Mark A. , Bailey Michael W.
Published: March 2021

Computer support of design analysis tasks is a key element in improving the productivity of design engineers. This undertaking is particularly difficult for preliminary design, where products are constantly evolving and therefore the required analyses change. Furthermore, because preliminary design requires quick turnaround, engineers must often rely on special-purpose analysis codes developed in-house by the engineers themselves. Thus, a computer tool for integrating such codes to support multi-disciplinary design must provide flexibility. The work presented here attempts to meet this requirement by combining object-oriented modeling with constraint propagation. Object-oriented techniques are intended to provide the modeling flexibility needed for preliminary design, while constraint propagation is a flexible means for integrating and performing mathematical analyses. The utility of this approach is demonstrated by its application to aircraft engine preliminary design. Current work in coupling the modeling software to a generic optimization package is also discussed.
A Robust Optimization Method for Systems With Significant Nonlinear Effects
Authors: Yu Jyh-Cheng , Ishii Kosuke
Published: March 2021

This paper describes a robust optimization methodology for design involving either complex simulations or actual experiments. The proposed procedure optimizes the worst case response that consists of a weighted sum of expected mean and response variance. The estimation scheme for expected mean and variance adopts the modified 3-point Gauss quadrature integration to assure superior accuracy for systems with significant nonlinear effects. We apply the proposed method to the robust design of geometric parameters of heat treated parts to minimize the cost of post heat treatment operations. The paper investigates the major factors influencing geometric distortions due to heat treatment and the rules of thumb in design. The study focuses on relating dimensional distortion to the design of part geometry. To illustrate the utility of the proposed method, we present the formulation of a case study on allocation of dimensions of preheat treated (green) shafts to minimize the cost of post heat treatment operations. The final result is not presented yet pending the completion of further experiments.
Robust Suspension System Design
Authors: Beard John E. , Sutherland John W.
Published: March 2021

Traditionally, levels for design variables are sought that produce optimal performance of a product. When manufacturing and assembly processes are used to realize the design intent, however, the product performance may differ from that envisioned during design. This is because the performance of a product is often very sensitive to manufacturing and assembly variations. This paper presents a methodology for robust design that incorporates the impact of manufacturing/assembly variations. The methodology characterizes the performance of a manufactured product via a loss function. The loss function measure is attractive from a robust design standpoint since it stresses both desirable performance on the average and small variation in performance from product to product.

The design methodology is demonstrated through a suspension system design application. A model for the kinematic behavior of a suspension system is developed. The scrub rate is selected as the response of interest to demonstrate the methodology. The behavior of the kinematic model, in terms of the loss function, is approximated near a set point and levels of the design variables are sought that minimize the loss. An iterative procedure is described for optimizing the loss function. The application demonstrates that substantial improvements can be made in terms of actual manufactured product performance through the use of the methodology.
Application of the Exact Gradient Approach in Optimal Synthesis of Mechanisms
Authors: Mariappan Jawaharlal , Krishnamurty Sundar
Published: March 2021

This paper presents the application of the unified exact gradient approach to optimal synthesis of mechanisms. The exact gradient approach is a systematic and efficient solution procedure that is applicable for any type of mechanism synthesis problem. In this approach, the exact gradients necessary for optimization are developed using a generalized solution procedure based on matrix methods. Availability of exact gradients in this approach enables the utilization of any gradient-based optimization method in mechanism synthesis process. As a result, this approach will be computationally most efficient, since it will not require direct search methods, or, finite difference approximate methods to find optimal solutions. These salient features of this approach are demonstrated with the aid of several mechanism problems and the results discussed.
A Genetic Algorithm for Solving Mixed Discrete Optimization Problems
Authors: Qian Zhihang , Yu Jun , Zhou Ji
Published: March 2021

A new optimal method based on genetic algorithms (GAs) is proposed here towards the mixed discrete optimization problems. This method has not only the advantages of high stability and wide adaptability but also a better chance of locating the global optimum. Its efficiency is much higher than that of simple genetic algorithms.
The Function of Value Engineering
Authors: Sturges Robert H.
Published: March 2021

Value Engineering (VE) techniques based on function have been the means to improved products and processes for several decades. It is a social design methodology that is usually episodic in application and often narrowly applied to cost cutting. This paper addresses the role, or function, of VE in a larger model of design practice to give insight into its use, non-use and misuse. The model identifies three aspects of design practice, with a dual functional activity at its center. The process of innovative design highlights the tension between these functions. We conclude that VE is neither a different nor a sufficient way to design compared with more conventional analytical and synthesis techniques. It is rather a parallel and necessary process with different inputs and outputs.
Automated Generation of Optimally Directed Three Dimensional Component Layouts
Authors: Szykman Simon , Cagan Jonathan
Published: March 2021

This research introduces a novel approach towards automating the generation of three dimensional component layouts. Three dimensional component layout tasks are typically highly combinatorial, and exhibit objective function spaces that can be nonlinear and/or discontinuous due to discrete allowable locations for component placement. We present an approach to the three dimensional component layout problem that employs shape annealing, a design generation technique combining concepts from shape grammars and simulated annealing, to produce optimally directed designs. The shape annealing paradigm sacrifices global optimality in exchange for the ability to find good designs in a reasonable amount of time, given very large, ill-behaved objective function spaces.
Computational Support for Interactive Cable Harness Routing and Design
Authors: Conru Andrew B. , Cutkosky Mark R.
Published: March 2021

We describe a system for routing cable harnesses in complex, three-dimensional environments. The approach taken is to automate the basic routing process as much as possible, while allowing designers to guide the system and modify the numerically generated results at any stage. The system begins by quickly generating a coarse routing based on an initial guess of the cable harness configuration (topological structure). Paths are then successively refined to minimize a cost function, while satisfying physical constraints such as minimum bending radius. Human input is useful both for guiding the system away from local minima and for responding to case-specific constraints not encoded in the router.
Hybrid Method for Multi-Target Parametric Design
Authors: Shah Jami J. , Wu Jian
Published: March 2021

This paper examines optimization techniques for parametric design based on statistical, mathematical, and heuristic models. A hybrid method is then proposed based on the strengths of several of these approaches. The new method, called multi-target parametric design method, combines Taguchi’s methodology, conventional (mathematical) optimization methods, and MANOVA statistical technique. It can be used to optimize composite utility functions, while satisfying the quality requirements. The method involves three main steps. First, by applying Taguchi’s method, the optimal quality is determined with a certain set of control variables. Second, these variables are transformed into variable constraints through a relaxing process. Finally, the optimization problem is solved for other design targets under these constraints, using conventional mathematical optimization methods or the Taguchi method.
Genesis of Ribbed Plate and Shells With Isotropic Density Dependent Material
Authors: Mlejnek Hans P.
Published: March 2021

An essential part in the genesis of structures or optimal material distribution is the relation between elastic behaviour and material density. This approach makes use of a isotropic material model, which leads to very simple working conditions. The isotropic model is directly formulated and utilized without employing homogenization based on an artificial microstructure. It is shown in theoretical considerations and demonstrated by examples, that this idea works also very easily with plate and shells, even for very general layer structures.
A Symbolic Approach to the Input-Output Analysis of the Stephenson Six-Bar Linkage
Authors: Zanganeh Kourosh E. , Angeles Jorge
Published: March 2021

In this paper, the authors present a symbolic approach to the calculation of all real angular positions of the output link of the Stephenson mechanism, associated with a given value of the angular position of the input link. Moreover, the input-output sextic polynomial of the mechanism is derived and numerical examples are provided for two of the inversions of the Stephenson linkage.
An Augmented Lagrange Multiplier Based Method for Mixed Integer Discrete Continuous Optimization and its Applications to Mechanical Design
Authors: Kannan B. K. , Kramer Steven N.
Published: March 2021

An algorithm for solving nonlinear optimization problems involving discrete, integer, zero-one and continuous variables is presented. The augmented Lagrange multiplier method combined with Powell’s method and Fletcher & Reeves Conjugate Gradient method are used to solve the optimization problem where penalties are imposed on the constraints for integer / discrete violations. The use of zero-one variables as a tool for conceptual design optimization is also described with an example. Several case studies have been presented to illustrate the practical use of this algorithm. The results obtained are compared with those obtained by the Branch and Bound algorithm. Also, a comparison is made between the use of Powell’s method (zeroth order) and the Conjugate Gradient method (first order) in the solution of these mixed variable optimization problems.
Optimal Approximation of Real Values Using Rational Numbers With Application to the Kinematic Design of Gearboxes
Authors: Pomrehn Leonard P. , Papalambros Panos Y.
Published: March 2021

This article proposes a method for optimally approximating real values with rational numbers. Such requirements arise in the design of various types of gear sets, where integer numbers of gear teeth force individual stage ratios to assume rational values. The kinematic design of an 18-speed gearbox, taken from the literature, is analyzed and solved using the proposed method. The method, called sequential exhaustion, sequentially considers each stage of the gearbox design, exhaustively examining each stage. Examination of 94 solutions leads to a pareto-optimal set containing 11 solutions. Further, although the layout of the gearbox is predefined for the kinematic design problem, certain solutions of the problem exhibit “non-reducing” gear pairs, revealing previously unforeseen changes in the gearbox layout.
Tolerance Allocation Considering Customer and Manufacturer Objectives
Authors: Söderberg Rikard
Published: March 2021

Involving customer values in the design process is necessary for improving the total quality of a product This paper presents the basic ideas for a method that allows tolerances to be assigned to dimensions in a tolerance chain with regard to both customer and manufacturer objectives. The method uses an extended “quality loss function” to consider customer objectives. The total life of a component is here focused, representing one important aspect of quality. A minimum manufacturing cost function for the tolerance of a critical dimension, dependent on a number of manufactured components, is determined. This function is used to consider manufacturers’ objectives. Based on the customer’s total loss function and the minimum manufacturing cost function, the optimal tolerance limits of a critical dimension are determined. These are the tolerances that simultaneously satisfy the customer and the manufacturer as much as possible.

The ideas behind the method are described using a roller bearing application as an example.
Automated Concurrent Design Based on Combined Feature, Tolerance, Production Process and Cost Models
Authors: Xue Deyi , Dong Zuomin
Published: March 2021

This paper presents a method for conducting automated concurrent design using combined feature, tolerance, production process and cost models. The introduced features are defined and examined in terms of design function, manufacturing method, and geometric shape and accuracy. The integrated design model has three functions: (a) facilitating the generation of all feasible designs by design feature-based knowledge reasoning using an intelligent CAD system; (b) representing various design information using the geometric primitives of a conventional CAD system; (c) describing a design using production process-oriented manufacturing features for evaluating manufacturability and production costs. This approach can incorporate manufacturing consideration into design phase and identify a cost-effective design satisfying given design functions and achieving minimum production costs. Functions of a prototype system are illustrated using an example.
On the Solution of Nonlinear Engineering Optimization Problems on Parallel Computers
Authors: Grauer Manfred , Boden Harald
Published: March 2021

This paper is intended to give an overview on nonsequential solution approaches in nonlinear optimization and an introduction to the OpTiX-II Decision Support System (DSS) for the solution of nonlinear optimization problems. The purpose of OpTiX-II is (i) to supply engineers/decision makers with the knowledge of an optimization and computer expert, (ii) to make use of modern computer technology (e.g. computer networks, parallel computers) for attaining faster and more reliable problem solutions and (iii) to supply an easy-to-use graphical interface for untrained computer users. Thereby OpTiX-II enables the user to solve nonlinear (decomposed) optimization problems on networks of (heterogeneous, parallel) computers. Currently, the multiprocessor architectures, which are supported by OpTiX-II, range from entry level workstations via multiprocessor Unix workstations to Transputerclusters. A gear reducer design optimization problem will be used for demonstrating the application of OpTiX-II.
Efficient Converters for Feature-Based Mechanical Component Representations
Authors: Rosen David W.
Published: March 2021

To enable the development of design-for-manufacturability tools for thin-walled mechanical components, converters are needed to convert design representations of components into representations with which manufacturability evaluations can be performed. In our work components are designed with features and represented as graphs. Conversely, manufacturing representations consist of manufacturing features, that in general are different than design features. Thus, the problem of converting feature-based representations arises. In this paper, manufacturing features are defined using graph grammars which provide a general, formal, structured description of how to convert features. Unfortunately, using graph grammar parsing as the basis for conversion is not computationally viable due to the nature of graph isomorphism determination. By taking advantage of the known structure of design representations and of manufacturing features, and by utilizing AI techniques for efficient pattern-matchers, it is shown that efficient converters can be constructed that do not require graph isomorphism determination. Conditions are given for the construction of polynomial time converters and a general conversion module is presented. An example converter is illustrated for tooling cost evaluation in injection molding and die casting.
A Hybrid Approach to Intelligent Geometric Design Using Features-Based Design and Feature Recognition
Authors: Gadh Rajit
Published: March 2021

The current article presents a new approach to computer aided design based on an abstract geometric entity called a C-loop (Convex/Concave-loop). The approach currently being developed overcomes design limitations in current systems. Design-by-features systems are fast, but not flexible. Design-by-surfaces systems are flexible but cumbersome to use. The current research integrates a design-by-features approach with a design-by-surfaces approach followed by feature recognition. It allows the designer to create a design using design features and to modify these features as needed. The C-loop is the design feature that allows such flexibility. Subsequent to the design step, features pertinent to manufacturing are recognized from the model to perform Design-for-Manufacturability evaluation of the part.
Dynamic Binding of Features and Solid Modelers
Authors: Shah Jami J. , Pherwani Viren
Published: March 2021

The work described in this paper investigates the feasibility of standardizing communications between geometric modeling core systems and generic feature-based applications. Since geometric modelers differ in the functionality they provide and feature applications vary in the level of geometric operations they can support internally, a multi-layered communication architecture is proposed. The methodology is analogous to the X-Window standard for graphics. At the lowest level is a library of functions named Geo-lib, which are translated into geometric modeler specific commands. If there was to be a future dynamic interfacing standard, such as STEP-SDAI, these specific calls could be replaced by standard calls, analogous to Geo-Protocol. At the next layer is a library, called Geo-widgets, which are written entirely using Geo-lib functions. At the highest level Geo-Tools, functions used commonly by generic applications. Feature applications can choose to use the library at any level, as necessary. This multi-layered geometric toolkit creates a seamless object oriented bond between the feature application and the geometric modeling core, in such a way that either one could be replaced without requiring any changes to the other.
A General Framework for Decomposition Analysis in Optimal Design
Authors: Wagner Terrance C. , Papalambros Panos Y.
Published: March 2021

Numerous methods exist in the literature for decomposing mathematical programming (MP) problems. The question for the designer wishing to utilize any of these methods is, what (if any) structure exists in a particular problem, and what (if any) decomposition method(s) may be appropriate for the problem at hand. The paper develops a formal methodology, termed Decomposition Analysis, to answer this question. Decomposition of a mathematical programming problem requires identification of linking variables or functions which effect independent optimization problems. Examination of prevalent methods reveals various structures in an MP problem which determine appropriate decomposition methods for a particular problem. An undirected graph representation of the MP problem facilitates rigorous identification of the desired structures that allow decomposition. The representation is the foundation of the methodology to analyze any particular MP problem for its decomposability.
A Fast and Robust Algorithm for Planar Intersection of Two Cones
Authors: Shene Ching-Kuang
Published: March 2021

In general, two quadric surfaces intersect in a space quartic curve. However, the intersection curve frequently degenerates to a collection of planar curves. These degenerate cases are often required by design. For example, to blend two cones with a Dupin cyclide or a quadric surface, the cones must have planar intersection. Moreover, degeneracies normally introduce problems into the general intersection algorithms and are difficult to implement in a reliable way. In this paper, we shall present a fast and robust algorithm to detect and compute the planar intersection curves, as well as a technique to find the types of the curves without actually computing them.
On Algebraic Methods for Implicit Swept Solids With Finite Extent
Authors: Ganter M. A. , Storti D. W. , Ensz M. T.
Published: March 2021

In this paper, we consider geometric construction of swept solids using algebraic methods based on classical envelope theory. Methods are presented for construction of algebraic swept solids with finite extent and variable geometry. Problems of local and global self-intersection (undercutting in the terminology of cam design) are considered, and void removal concepts are demonstrated. Examples presented include offsets of Bezier curves and twisted sweeps with ellipsoidal primitives.
Ratio and Difference Estimation in Multi-Criteria Decision Analysis
Authors: Lootsma F. A.
Published: March 2021

Since decisions are invariably made within a given context, we model relative preferences as ratios of increments or decrements in an interval on the axis of desirability. Next, we sort the ratio magnitudes into a small number of categories, represented by numerical values on a geometric scale. We explain why the Analytic Hierarchy Process (AHP), typically based on a pairwise-comparison method, is concerned with category judgement of ratio magnitudes, whereas the Simple Multi-Attribute Rating Technique (SMART) essentially uses the orders of magnitude of these ratios. This provides a common basis for the analysis of the methods in question and for a cross-validation of their results. The present paper summarizes the basic assumptions and the relationship between the two methods.
Bubble-Method: A Special Strategy for Finding Best Possible Initial Designs
Authors: Eschenauer Hans A. , Schumacher A.
Published: March 2021

The position and the arrangement of structural elements in a component — also defined as its topology — decisively influences its deformation and stress behaviour. When developing a new component it is essential to find an optimal topology. The objective of topology optimization is to substitute the existing intuitive design of variants by mathematical-mechanical strategies in the design phase and thus to make it more efficient.

In this paper a special method is introduced, the basic idea of which is to iteratively position new holes, so-called bubbles, in the structure of a component. Therefore, the method is called “Bubble Method”. The bubbles are iteratively positioned by means of various methods, among others by solving a variational problem. The insertion of bubbles signifies a change of the topology class. For the different topology classes, hierarchically subordinate shape optimizations are carried out which determine the optimal shape of the specific new bubble together with the other variable boundaries of the component. The advantages of such a topology optimization method in comparison to traditional, intuitive variant designs are demonstrated by means of a panel-truss-structure.
An Interactive Environment for Multibody Simulation
Authors: Lynch James D. , Vanderploeg Martin J.
Published: March 2021

Simulation of three dimensional multibody systems is a sophisticated analysis tool that is often used for design. Before a prototype is constructed, simulation provides a designer with a model that can be modified until a desired result is achieved. General purpose multibody dynamics packages are currently used around the world.

During the evolution of multibody simulation, three dimensional graphics became an important tool for both system definition and evaluation of simulation results. In fact, three dimensional graphics was an enabling technology for simulation of large, complex three dimensional systems. However, the process has remained essentially a batch operation in which the analysis of the results is not accessible until the solution is complete. Changes in the model require starting the process over.

Although the use of computer simulation in the place of early prototypes was a significant step forward in terms of reduced time and cost to develop a design, even more improvement is possible when the user is able to interactively change and analyze the system at any time in lieu of having to go through discrete trial and error steps.

In order to reach this next level, this paper introduces an interactive computer graphics interface for three dimensional multibody dynamic simulation.
Optimal Design of Forging Processes With Deformation and Temperature Constraints
Authors: Grandhi R. V. , Cheng H. , Kumar S. S.
Published: March 2021

This paper presents a systematic methodology for the design of process parameters for nonisothermal forgings. The finite element approach is used for deformation and thermal analyses, and an optimal control strategy is used for the process parameter design. A state-space model is developed for representing the coupled deformation and thermal behavior using rigid viscoplastic formulation. Design constraints on strain-rates and temperature variation are imposed for achieving the desired forging conditions. The linear quadratic regulator (LQR) theory for finite time control is used in designing the ram velocity and initial die temperature. The approach is demonstrated on an axisymmetric disc forging and a plane strain channel section forging, under nonisothermal conditions.
The Implementation of STEP Schemas
Authors: Burkett William C.
Published: March 2021

The Standard for the Exchange of Product model data (STEP - ISO 10303) is an international standard for the communication of product information between heterogenous systems. In this presentation, the question of how STEP should be implemented is examined. The objectives of the STEP Development process are presented and the resulting effect that these objectives had on the structure of the standard is explained. However, conflicting objectives resulted in a structure that lacked appropriate mechanisms for dealing efficiently with implementation considerations. The STEP Development Process is compared/contrasted with a database design process to discern where implementation considerations (i.e., tuning, optimization) should take place within the process. A technical architecture for the standard is presented and a missing component of the standard is identified and explained: the Implementation Schema. Current STEP efforts with respect to Implementation Schemas are then presented.
COMSUBLANT Pump and Valve Repair System
Authors: Mueller Joseph B.
Published: March 2021

Flexible Computer Integrated Manufacturing (FCIM) technology existing today in industry, combined with modern repair processes, can be used to address erosion and corrosion inherent in submarine and surface ship fluid systems. Commander Submarine Force Atlantic Fleet (COMSUBLANT) will implement in the near future a Pump and Valve Repair System in the Trident Refit Facility (TRF), Submarine Base, Kings Bay, Georgia. The system will support the repair of submarine and surface ship components such as valve bodies, valve tailpieces, and pump casings. It will replace metal lost by erosion and corrosion using repair processes such as automated welding and epoxy spray and reliably return these components to original specification with computer numerical control (CNC) machining.
The NIST EXPRESS Toolkit: Design and Implementation
Authors: Libes Don
Published: March 2021

The NIST EXPRESS toolkit is a software library for building EXPRESS-related tools. EXPRESS is an ISO language for describing information models. EXPRESS descriptions are neutral to different data storage paradigms and systems on different hardware platforms and networks.

This paper describes the design and implementation of the toolkit including its important interfaces, data structures, and algorithms. This paper is recommended for anyone wishing to modify the toolkit or anyone wishing to build their own EXPRESS implementation. The reader is assumed to be familiar with the EXPRESS language, the basics of traditional language implementations, and C — the language with which the toolkit is implemented.

As a testbed against which to benchmark the evolving EXPRESS language, conformance to the standard (currently Draft International Standard) is the highest priority in the toolkit. Nonetheless, time/space efficiency, accurate and helpful diagnostics, and ease-of-use are also critical to the success of the toolkit. The paper describes how these concerns are addressed even though EXPRESS is a complex and sophisticated language.

The toolkit is available from the National Institute of Standards and Technology. The toolkit is just one of a number of tools for data management in STEP, a family of ISO standards currently in development. All of the NIST tools, including the NIST EXPRESS toolkit, are in the public domain.
Developing Design Solutions Using the Frames Technique of Knowledge Representation
Authors: Wyatt Timothy R. , Holtz Neal , Rasdorf William J.
Published: March 2021

With computer aids becoming more prevalent in the design process, the problem arises as to how best represent the design artefact for both the computer tool and the design engineer. This paper introduces the frames technique, an artificial intelligence concept, and examines its suitability as a solution to this design engineering problem. The frames technique was selected over other representational formalisms because it resides at the conceptual modeling level, and, therefore, can represent a wide range of data types. This paper contains a background discussion on frames theory, based on Winston’s model, and presents a controlled experimental study of the frames technique for the design of a conceptual model, using an application from the architecture/engineering domain.
Echolocation click parameters of short-finned pilot whales (Globicephala macrorhynchus) in the wild
Authors: Pedersen M. B. , Tønnesen P. , Malinka C. E. , Ladegaard M. , Johnson M. , Aguilar de Soto N. , Madsen P. T.
Published: March 2021

Short-finned pilot whales (Globicephala macrorhynchus) are large, deep-diving predators with diverse foraging strategies, but little is known about their echolocation. To quantify the source properties of short-finned pilot whale clicks, we made 15 deployments off the coast of Tenerife of a deep-water hydrophone array consisting of seven autonomous time-synced hydrophone recorders (SoundTraps), enabling acoustic localization and quantification of click source parameters. Of 8185 recorded pilot whale clicks, 47 were classified as being recorded on-axis, with a mean peak-to-peak source level (SL) of 181 ± 7 dB re 1 μPa, a centroid frequency of 40 ± 4 kHz, and a duration of 57 ± 23 μs. A fit to a piston model yielded an estimated half-power (–3 dB) beam width of 13.7° [95% confidence interval (CI) 13.2°–14.5°] and a mean directivity index (DI) of 22.6 dB (95% CI 22.5–22.9 dB). These measured SLs and DIs are surprisingly low for a deep-diving toothed whale, suggesting we sampled the short-finned pilot whales in a context with little need for operating a long-range biosonar. The substantial spectral overlap with beaked whale clicks emitted in similar deep-water habitats implies that pilot whale clicks may constitute a common source of false detections in beaked whale passive acoustic monitoring efforts.
Searching for Balance: A Historian’s View of the Fractured World of Kinesiology
Authors: Vertinsky Patricia
Published: March 2021

In this essay, I drew upon the perspectives of Walter Benjamin’s “angel of history” in reflecting upon the history of kinesiology and the influences that led to my own academic career in kinesiology. I have outlined how my disciplinary training as a physical educator and educational historian provided the resources to propel my continuing inquiry into the inter- and cross-disciplinary (and intrinsically entangled) nature of kinesiology. Gender, nationality, training, location, and timing all had their influences on my education and job opportunities and upon building toward a career in a research university where physical education and kinesiology, by design and accident, increasingly separated from one another. From the perspective of a sport historian, I suggest that the language and pursuit of balance might be applied productively to thinking about the future of kinesiology. Sport historians can help in this mission by training a critical lens upon the ongoing traffic between nature and culture and the deep sociocultural situatedness of the science and technology practices used in kinesiology teaching and research in the 21st century. In essence, they can illuminate the historical context of the tools that now frame kinesiology’s questions and the political context in which their answers emerge.
γδ T cells regulate the intestinal response to nutrient sensing
Authors: Sullivan Zuri A. , Khoury-Hanold William , Lim Jaechul , Smillie Chris , Biton Moshe , Reis Bernardo S. , Zwick Rachel K. , Pope Scott D. , Israni-Winger Kavita , Parsa Roham , Philip Naomi H. , Rashed Saleh , Palm Noah , Wang Andrew , Mucida Daniel , Regev Aviv , Medzhitov Ruslan
Published: March 2021

γδ T cells link immunity to nutrition

Gamma delta (γδ) T cells are immune cells best known for host barrier defenses in epithelial tissues. Sullivan
et al.
discovered a previously unrecognized role for γδ T cells in sensing nutrient uptake in the small intestine (see the Perspective by Talbot and Littman). The researchers analyzed mice fed a high-carbohydrate versus a high-protein diet and observed remodeling of the small intestinal epithelium in response to dietary carbohydrates. Nutrient availability triggered an epithelial–immune cell circuit that was required for digestion and absorption of carbohydrates. Intestinal γδ T cells regulated the expression of a carbohydrate transcriptional program by limiting interleukin-22 production from type 3 innate lymphoid cells. These findings may also provide insights into how γδ T cells modulate metabolic disease.

Science
, this issue p.
eaba8310
; see also p.
1202
Detection of two interstellar polycyclic aromatic hydrocarbons via spectral matched filtering
Authors: McGuire Brett A. , Loomis Ryan A. , Burkhardt Andrew M. , Lee Kin Long Kelvin , Shingledecker Christopher N. , Charnley Steven B. , Cooke Ilsa R. , Cordiner Martin A. , Herbst Eric , Kalenskii Sergei , Siebert Mark A. , Willis Eric R. , Xue Ci , Remijan Anthony J. , McCarthy Michael C.
Published: March 2021

Identifying PAHs in space

Midinfrared spectroscopy has shown that polycyclic aromatic hydrocarbons (PAHs) are abundant in many astronomical objects, but this technique cannot determine which specific PAH molecules are present. Radio astronomy could provide individual identifications if the molecule is sufficiently abundant and has a large dipole moment, but PAHs are expected to produce large numbers of very weak lines. McGuire
et al.
performed a stacking and matched filter analysis to search for PAHs in radio observations of TMC-1, located within the interstellar Taurus Molecular Cloud. They identified emission from two isomers of the small PAH cyanonapthalene, two fused benzene rings with a CN group attached.

Science
, this issue p.
1265
Gate-controlled BCS-BEC crossover in a two-dimensional superconductor
Authors: Nakagawa Yuji , Kasahara Yuichi , Nomoto Takuya , Arita Ryotaro , Nojima Tsutomu , Iwasa Yoshihiro
Published: March 2021

Inducing a crossover

In conventional superconductors, the electron pairs responsible for superconductivity are large and overlapping. Starting from this so-called Bardeen-Cooper-Schrieffer (BCS) limit, increasing interactions can set the system on a path of crossover to the opposite limit of small, tightly bound electron pairs that undergo Bose-Einstein condensation (BEC). Nakagawa
et al.
intercalated lithium ions into the insulating material zirconium nitride chloride, varying the carrier density across a large range (see the Perspective by Randeria). This induced superconductivity and enabled the system to enter the crossover regime between the BCS and BEC limits.

Science
, this issue p.
190
; see also p.
132
Detoxification Esterase StrH Initiates Strobilurin Fungicide Degradation in
Hyphomicrobium
sp. Strain DY-1
Authors: Jiang Wankui , Gao Qinqin , Zhang Lu , Liu Yali , Zhang Mingliang , Ke Zhijian , Zhou Yidong , Hong Qing
Published: March 2021

Strobilurin fungicides have been widely acknowledged as an essential group of pesticides worldwide. So far, their residues and toxic effects on aquatic organisms have been reported in different parts of the world.
Deciphering a Cyclodipeptide Synthase Pathway Encoding Prenylated Indole Alkaloids in Streptomyces leeuwenhoekii
Authors: Zhang Yuqiao , Yao Tingting , Jiang Yuechen , Li Huayue , Yuan Weicheng , Li Wenli
Published: March 2021

Natural products with a 2,5-diketopiperazine (2,5-DKP) skeleton have long sparked interest in drug discovery and development. Recent advances in microbial genome sequencing have revealed that the potential of cyclodipeptide synthase (CDPS)-dependent pathways encoding new 2,5-DKPs are underexplored.
Specificity of SARS-CoV-2 Real-Time PCR Improved by Deep Learning Analysis
Authors: Alouani David J. , Rajapaksha Roshani R. P. , Jani Mehul , Rhoads Daniel D. , Sadri Navid
Published: March 2021

Real-time PCR (RT-PCR) is widely used to diagnose human pathogens. RT-PCR data are traditionally analyzed by estimating the threshold cycle (

C
T

) at which the fluorescence signal produced by emission of a probe crosses a baseline level.
Quantitative Approach To Assess Influenza A Virus Fitness and Transmission in Guinea Pigs
Authors: Danzy Shamika , Lowen Anice C. , Steel John
Published: March 2021

Influenza pandemics occur when an IAV from nonhuman hosts enters the human population and adapts to give rise to a lineage capable of sustained transmission among humans. Despite recurring zoonotic infections involving avian- or swine-adapted IAVs, influenza pandemics occur infrequently because IAVs typically exhibit low fitness in a new host species.
Valosin-Containing Protein/p97 Plays Critical Roles in the Japanese Encephalitis Virus Life Cycle
Authors: Sehrawat Sapna , Khasa Renu , Deb Arundhati , Prajapat Surendra Kumar , Mallick Suvadip , Basu Anirban , Surjit Milan , Kalia Manjula , Vrati Sudhanshu
Published: March 2021

Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis epidemics in Southeast Asia, affecting mostly children, with high morbidity and mortality. Identification of host factors is thus essential for the rational design of antivirals that are urgently need as therapeutics.
In Situ Generated Nickel Phosphide Based Catalysts for Hydroprocessing of Levulinic Acid
Authors: Golubeva M. A.
Published: March 2021

This article describes the production of unsupported nickel phosphide
catalysts generated in situ in а reaction mixture from water-soluble and
oil-soluble precursors during the hydroconversion of levulinic acid. These
catalysts contain crystalline phases, specifically
Ni12P5 and
Ni(PO3)2. During the
hydrogenation of levulinic acid in toluene in the presence of NiP–TOP, a lower
temperature and a shorter reaction time contribute to the formation of
γ-valerolactone (100% selectivity). A higher temperature and a longer reaction
time favor the formation of valeric acid (94% selectivity). In the hydrogenation
of levulinic acid in ethanol in the presence of
NiP–H3PO2, the main reaction
product is ethyl levulinate (95% selectivity).
Riga-Fede disease: a mimicker of malignancy
Authors: Lakshmanan Somu , Venkataraman Srinivasan , Singh Urvashi
Published: March 2021

Riga-Fede disease (RFD), also known as traumatic eosinophilic granuloma, is a benign inflammatory condition of the oral cavity that may mimic a malignant tumour. It’s a rare condition mainly reported in infants. We present a unique case report of a 57-year-old man who presented to our outpatient department with foreign body sensation in the throat and swelling over the dorsum of the tongue for a period of 1 month. He gave no history of trauma, especially due to sharp teeth. Video laryngoscopy done revealed an ulceroproliferative growth on the midline of the dorsum of the tongue. With clinical suspicion of malignancy, the patient underwent wide local excision of the tongue lesion. Histopathological examination was suggestive of RFD. The postoperative follow-up was uneventful with good wound healing. The patient was followed up with no evidence of recurrence.
Rare presentation of anti-GAD-65 antibody-positive autoimmune encephalitis and simultaneous onset of type 1 diabetes mellitus in a paediatric patient
Authors: Kern Kristina , Shuster Brooke A
Published: March 2021

A 16-year-old female patient presented with subacute onset of headaches, changes in acute mental status, expressive aphasia and auditory hallucinations. New oedema and enhancement of the temporal lobe were seen on brain MRI, with correlating subclinical seizures seen on electroencephalogram. Simultaneously, our patient was diagnosed with new-onset type 1 diabetes mellitus, with positive anti-glutamic acid decarboxylase (anti-GAD-65) antibodies in the serum. Cerebrospinal fluid studies remained negative, including anti-GAD-65 antibodies. Clinical remission was achieved with corticosteroids and intravenous immunoglobulins.
Pontine stroke mimicking Bell’s palsy: a cautionary tale!
Authors: Dunphy Louise , Kaur Ravpreet , Flossmann Enrico
Published: March 2021

Stroke has been called apoplexy since the ancient times of Babylonia. Johann Jakob Wepfer, a Swiss physician, first described the aetiology, clinical features, pathogenesis and postmortem features of an intracranial haemorrhage in 1655. Haemorrhagic and ischaemic strokes are the two subtypes of stroke. Bell’s palsy usually presents with an isolated facial nerve palsy. A lacunar infarct involving the lower pons is a rare cause of solitary infranuclear facial paralysis. The authors present the case of a 66-year-old woman presenting with a 3-day history of headache, vertigo, nausea, vomiting and facial weakness. Her comorbidities included diabetes, hypertension and hypercholesterolaemia. It was challenging to identify the pontine infarct on MRI due to its small size and the confounding presentation of complete hemi-facial paralysis mimicking Bell’s palsy. Our case provides a cautionary reminder that an isolated facial palsy should not always be attributed to Bell’s palsy, but can be a presentation of a rare dorsal pontine infarct as observed in our case. Anatomic knowledge is crucial for clinical localisation and correlation.
Intravenous cannula used for continuous intraoral mandibular nerve block in trigeminal neuralgia
Authors: Stringer Harriet Katharine , Borumandi Farzad
Published: March 2021

Trigeminal neuralgia is a chronic pain condition affecting one or more distributions of the trigeminal nerve. Patients with this condition experience short, sharp, shooting pain attacks, which can progress to longer, more frequent durations. The pain is often difficult to control. We report of a man who was admitted with severe neuralgia of the third division of the trigeminal nerve. Talking and any oral intake triggered a severe agonising pain. The latter made the regular oral intake of analgesia challenging. The pain was temporarily controlled with frequent local anaesthesia (LA). Dental core trainees were performing regular inferior alveolar nerve blocks which significantly improved patients’ condition allowing him to communicate and have oral intake. Subsequently, a catheter was placed allowing for a continuous anaesthesia. The connecting tube of the cannula was then used by nursing staff to administer LA providing pain relief without the need of repeated intraoral injections.