bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling of a Hydraulic Lash Adjuster With Experimental Identification in Oil Refill Mechanism
Authors: Hsu Wensyang , Pisano Albert P.
Published: March 2021

Hydraulic lash adjusters can eliminate clearance between components in the automotive valve trains. A two-mode dynamic model for the adjuster is derived by including check valve motions at two operating modes. The oil refill mechanism controlled by the check valve is experimentally identified. The oil compressibility in the oil chamber and the oil leakage through the annular gap between the plunger and the body are also considered.

It is shown that motion of the adjuster plunger must satisfy a third-order, non-linear differential equation of motion. The differential equation is numerically integrated, and the experimental data in leak-down test provided by the manufacturer is shown to be in good agreement with the model.

The annular gap is found to be the key factor in controlling leak-down speed, and the effective orifice diameter is shown to be the key factor in describing the pump-up phenomenon. It is also found that one percent air entrainment in the oil chamber of the adjuster seriously compromises overall adjuster rigidity and reduces the natural frequency of the adjuster almost 50 percent.
Determination of Failure Probabilities and Sensitivity Factors Based on First Order Reliability Method
Authors: Parameswaran Nataraj , Kjerengtroen Lidvin
Published: March 2021

Traditionally, most engineering problems are modeled in such a manner that all the variables involved in the design equations are deterministic. By nature, however, seldom does such a phenomenon exist. Most of the variables involved are randomly distributed with a certain mean and standard deviation and follow a certain type of statistical distribution. This investigation compares two such statistical based design processes to evaluate failure probabilities of a one dimensional heat transfer problem with various statistically distributed parameters in its performance function.

The methods developed are the Monte Carlo simulation and First Order Reliability Method (FORM). Comparison is made between the Monte Carlo simulation and FORM based upon the investigated problem and the relative advantages and disadvantages of both methods are noted at the end of the investigation. The investigation demonstrates that FORM can be used effectively to determine failure probabilities and sensitivity factors in a manner better than Monte Carlo simulation.
Coding and Clustering of Design and Manufacturing Features for Concurrent Design
Authors: Xue D. , Dong Z.
Published: March 2021

In this work, a mechanical design is represented using design features and manufacturing features. A design function based design feature representation is introduced. This representation allows design candidates to be generated by a pattern match search in the design feature library, according to given design requirements. A fuzzy c-means clustering algorithm has been used for organizing design features in a large feature library. A fast feature searching scheme has been developed for quick feasible design identification. The manufacturing feature representation is based upon the geometric primitives produced by various manufacturing operations. The representation can provide a useful design database for manufacturing tasks. It also provides a list of necessary manufacturing processes and their associated costs for manufacturing each design candidate. The method supports the generation of multiple design solutions and joint evaluation of design performance and manufacturing costs, thus providing the basis of concurrent engineering design. The design feature and manufacturing feature coding methods are tested using a prototype feature-based, integrated concurrent engineering design system.
Robust Parameter Design of the Precision Injection Molding Process
Authors: Leartcheongchowasak Sornkrit , Mehta Merwan , Al-Kadi Hamid , Sequeira Keith , Snow Brian , Ragsdell Kenneth W. , Baja Louis
Published: March 2021

The most important problem, causing defective parts, in the injection molding process, is nonuniform shrinkage of molded parts. This leads to an iterative trial-and-error cycles of modification of mold cavity and core to arrive at the right dimensional size required which can occasionally to complete retooling. For this process, there are many factors that can be thrown out of control. Using the traditional scientific approach, engineers have longed to understand the mechanics of the process to control it, with limited success. In this paper, a design of experiments setup, using the Taguchi Methods, was done to reduce the nonuniform shrinkage. The company where the experiment was carried out is a precision parts molder for their own product lines. By using the internal experts from the company, a list of independent process parameters with no interactions which were thought the most responsible for dimensional size were listed. As there were 13 such parameters, it was decided to use the L27 orthogonal array. The optimum value that the company experts thought would produce the right part were used as the settings for the initial experiment. The 27 experiments were then performed, allowing sufficient time to let the machine stabilized between the experiments. The S/N ratio calculation for 27 experiments was explained. Next the calculations for the percentage that each parameter contributes to the dimension was determined. Finally, a confirmation experiment was performed to verify the results.
Parallel Disassembly by Onion Peeling
Authors: Chen Shiang-Fong , Oliver James H. , Chou Shuo-Yan , Chen Lin-Lin
Published: March 2021

For some assembly structures, parallel disassembly of components is necessary in order to reach a particular internal component. Due to the large number of possible combinations, the parallel disassembly problem is not easily solved in a general form. This paper addresses parallel disassembly via geometrical reasoning and presents an algorithm for finding a sequence to disassemble a structure by an onion peeling procedure, from outside to inside. This algorithm takes Max{O(N3), O(E)} time to find an efficient sequence to reach a particular component, where N is the number of components and E is the number of mating faces. In this algorithm, the disassemblability of various combinations of components are determined by traversing the mating graph of the structure and testing the monotonicity of paths in the graph. Separability testing is incorporated to determine whether the query components can be disassembled and moved to infinity without obstruction.
PARDEC: A Parallel Decomposition Algorithm for Non-Hierarchical Systems or Structures
Authors: Eschenauer Hans A. , Weinert Matthias
Published: March 2021

The present paper introduces a decomposition algorithm for non-hierarchical systems or structures. The algorithm coordinates the created subsystem optimization problems by means of an approximation strategy. It is implemented on a parallel computing system and will be verified on shape optimization problems.
Composite Laminate Stiffnesses and Their Sensitivities
Authors: Geier Bodo , Zimmermann Rolf
Published: March 2021

The great number of possible stacking orders to form laminates suggests to apply optimization, more frequently than usual, in the design of structures made of composite materials. One of the columns upon which optimization of structures is built is the mathematical search procedure for locating a minimum (or maximum) of a constrained function. Efficient algorithms will require the evaluation of derivatives of the object function as well as of the constraints. In that context the sensitivities of laminate stiffness matrices may be required.

In order to meet such a requirement the derivatives with respect to both ply thicknesses and ply angles, of laminate stiffnesses, including transverse shear stiffness, will be presented in this report.
Structural Sensitivity Analysis in Eigenvalue Problems Using Finite Strip Method
Authors: Garstecki Andrzej , Kakol Witold
Published: March 2021

Structural Sensitivity Analysis is performed using the direct differentiation method for buckling and free vibration problems of prismatic thin-walled structures employing the Finite Strip Method. The sensitivity of eigenvalues (critical stresses and free frequencies) with respect to variation of thickness of plate members and with respect to shape-type variations is considered. The differentiation is carried out employing analytical and semi-analytical methods. Numerical examples illustrate the sensitivity of thin-walled plates stiffened with ribs and thin-walled beams. The examples also serve for discussion of numerical efficiency and accuracy of the presented methods.
Stable Workpiece Fixturing
Authors: Donoghue Joseph P. , Howard W. Stamps , Kumar Vijay
Published: March 2021

In this paper, we present the spatial and planar force-displacement relationships which characterize individual contacts on a fixtured workpiece. The compliance at each contact is modeled and expressions for the changes in contact forces as a function of the rigid body relative motion between the fixture elements and the workpiece are developed for three-dimensional fixtures. Using these relationships, the stable fixturing of planar workpieces is demonstrated for material-removal operations. By example, we first describe how to choose the clamp geometry so the overall movement of the workpiece is minimized and then determine the “best” two-contact clamping arrangement using a quality measure based on the deviation from the nominal part dimensions.
Optimization of Stirling Engine Performance Based on Multipoint Approximation Technique
Authors: Toropov Vassili V. , Carlsen Henrik
Published: March 2021

The ideal Stirling working cycle has the maximum obtainable efficiency defined by Carnot efficiency, and highly efficient Stirling engines can therefore be built, if designed properly. To analyse the power output and the efficiency of a Stirling engine, numerical simulation programs (NSP) have been developed, which solve the thermodynamic equations.

In order to find optimum values of design variables, numerical optimization techniques can be used (Bartczak and Carlsen, 1991). To describe the engine realistically, it is necessary to consider several tens of design variables. As even a single call for NSP requires considerable computing time, it would be too time consuming to use conventional optimization techniques, which require a very large number of calls for NSP. Furthermore, objective and constraint functions of the optimization problem present some level of noise, i.e. can only be estimated with a finite accuracy. To cope with these problems, the multipoint explicit approximation technique is used.
Approximate Kinematic Equations for Multiple-Input Small-Crank Mechanisms: Four-Bar Based Mechanisms
Authors: Farhang Kambiz , Basu Partha S.
Published: March 2021

Approximate kinematic equations are developed for multiple-input small-crank mechanisms derived from a basic planar four-bar linkage. Application of a method in which an output link is presumed to comprise a mean and a perturbational motions, the vector loop approach, and a recursive formulation facilitates derivation of the approximate kinematic equations. For a general n-input mechanism, two sets of constraint equations are established: a set of nonlinear recursive equations relating the mean link orientations and a set of linear recursive equations for the purturbational motions. The recursive procedure is demonstrated by developing approximate kinematic equations for four-bar based two-, three- and four-input small-crank mechanisms.
Instantaneous Invariants and Curvature Analysis for Planar Mechanisms
Authors: Yang An Tzu , Pennock Gordon R. , Hsia Lih-Min
Published: March 2021

This paper establishes a systematic procedure to determine the instantaneous invariants for a member in a planar mechanism and the curvature ratios of the path of a point fixed in the member. Closed-form expressions are derived for the instantaneous invariants and the curvature ratios as continuous functions of the input variable of the mechanism. The methods that are proposed in this paper can be applied to the design of planar mechanisms in general. For a given mechanism, the configuration defined by the input variable at which the member achieves the optimal approximation of a prescribed rigid motion can be determined. Alternatively, a point fixed in a member can be selected such that it will generate a trajectory matching a given curve with high precision. For purposes of illustration, the paper details the analytical procedure for a simple epicyclic gear train and a four-bar mechanism. The instantaneous invariants and the curvature ratios are generated for the complete operating cycle of each mechanism.
Polynomial Solution of the Spatial Burmester Problem
Authors: Innocenti Carlo
Published: March 2021

The paper presents a new method for the dimensional synthesis of the spatial guidance linkage that features the guided body connected to the base by the interposition of five rods having spherical joints at both extremities. The linkage is required to index the guided body through seven arbitrarily-chosen rigid-body positions. Core of the proposed method is an original algebraic elimination procedure that allows five unknowns to be dropped from a set of six second-order algebraic equations in six unknowns. As a result, a final univariate polynomial equation of twentieth order is obtained whose twenty roots, in the complex domain, represent as many possible placements for a connecting rod. A numerical example is reported.
Graphical Synthesis of Optimal High-Performance Four-Bar Mechanisms
Authors: Khanuja Sukhwant S. , Mettlach Gregory A. , Midha Ashok
Published: March 2021

Graphical mobility analysis methods are used to develop a comprehensive four-bar mechanism synthesis technique. Given the mobility angle and length of a side link, simple graphical tools are used to obtain the solution space satisfying a variety of constraints on link lengths. This can be done with great accuracy using standard CAD packages. The solution space is then searched for an optimal high-performance mechanism. The objective function seeks to minimize the higher harmonic content in the acceleration of the output member. The graphically generated solution space greatly reduces the search domain of the optimization process. It also readily provides initial estimates for the optimization scheme. Several examples are used to illustrate the methodology.
A More Effective Formulation of the Path Generation Mechanism Synthesis Problem
Authors: Ullah Irfan , Kota Sridhar
Published: March 2021

Use of mathematical optimization methods for synthesis of path-generating mechanisms has had only limited success due to the very complex nature of the commonly used Structural Error objective function. The complexity arises, in part, because the objective function represents not only the error in the shape of the coupler curve, but also the error in location, orientation and size of the curve. Furthermore, the common introduction of timing (or crank angle), done generally to facilitate selection of corresponding points on the curve for calculating structural error, has little practical value and unnecessarily limits possible solutions. This paper proposes a new objective function, based on Fourier Descriptors, which allows search for coupler curve of the desired shape without reference to location, orientation, or size. The proposed objective function compares overall shape properties of curves rather than making point-by-point comparison and therefore does not requires prescription of timing. Experimental evidence is provided to show that it is much easier to search the space of the proposed objective function compared to the structural error function.
Metric Relations and Displacement Groups in Mechanism and Robot Kinematics
Authors: Fanghella Pietro , Galletti Carlo
Published: March 2021

This paper presents a systematic theory for metric relations between the invariant properties of displacement groups, and shows this theory application to mechanism kinematics. Displacement groups, their invariant properties and operations are briefly described. Kinematic constraints are then introduced as tools for relating abstract group properties to actual mechanism constraints. Criteria and operating rules to employ metric relations for the generation of a meaningful set of closure equations for kinematic chains are detailed.
Determination of Branch Free and Circuit Free Solutions During Synthesis of Multiloop Mechanisms
Authors: Mariappan Jawaharlal , Krishnamurty Sundar
Published: March 2021

This paper presents the development of a generic method for the identification of branches and circuits in multiloop mechanisms. This paper also addresses the interrelationship that exists between branches and circuits, and offers a methodical solution procedure for determining branch free and circuit free solutions during synthesis. In this work, the sub-Jacobian method that was earlier developed for finding branching occurrences is further extended to enable identification of circuits and their mobility ranges corresponding to each branching configuration. Using this approach, the circuit analysis is performed by first finding the individual mobility regions of the various loops in the mechanism and then by forming their intersections. The application of this method is illustrated with the aid of six and eight-bar mechanisms.
Unsymmetric Four-Bar Straight-Line Mechanisms With Completely Balanced Deviation
Authors: Gassmann Volker , Funk Wolfram
Published: March 2021

This paper describes a generalisation of straight-line mechanisms of Tchebycheff-type. Tchebycheff considered symmetric four-bar mechanisms for which the part of the coupler curve used as an approximation for a straight line oscillates between two lines, so that one line is a tangent of the coupler curve in three points and the other is a tangent of the coupler curve in two points and intersects the coupler curve in two further points. The described synthesis methods allow the calculation of unsymmetric mechanisms which have the same characteristic oscillation and are also optimal in the sense of the approximation theory developed by Tchebycheff. The use of continuation methods not only enabled the solution of a classical kinematic problem and the possibility to synthesize straight-line mechanisms with desired characteristic values but also offers new possibilities for user-friendly software for kinematic synthesis.
A Method for Generating Geared Links From Linkages
Authors: Wang Wan , Li Guen Xie , Tao Yong Zhong
Published: March 2021

A concept of generating geared links by inverting general linkages is proposed, which is based on the topological graph, and applies substitution principle of mechanisms. It makes it possible to apply the methods, data and computer programs of general linkages to geared links.
Application of Learning Control Theory to Mechanisms: Part 2 — Reduction of Residual Vibrations in High-Speed Electromechanical Bonding Machines
Authors: Chew M. , Phan M.
Published: March 2021

Learning control provides an integrated approach for handling inverse kinematics and inverse dynamics of mechanisms, in the presence of parametric errors in system modeling. This technique is applied to reduce residual vibrations at the bonding cap of an electromechanical bonding machine for integrated circuits (ICs); a process of electrically linking silicon chips to the leads. The bonding cap trajectory for the bonding motion is actuated by high-speed cams driven by electric motors. The primary causes of residual vibrations are due to errors in the design model of the nonlinear electromechanical system, in camshaft speed control, as well as, in cam profile fabrication. This article demonstrates the capability of learning control to reduce the residual vibrations in such machines, by compensating for these sources of errors.
A Note on the Experimentally-Determined Elastodynamic Response of a Slider-Crank Mechanism Featuring a Macroscopically-Smart Connecting-Rod With Ceramic Piezoelectric Actuators and Strain Gage Sensors
Authors: Thompson B. S. , Tao X.
Published: March 2021

An experimental investigation is presented into the elastodynamic flexural response of a smart flexible connecting-rod of a planar slider-crank mechanism which features both macroscopic actuators and sensors. This connecting-rod was synthesized with two thin PZT ceramic piezoelectric plate actuators bonded to the flanks of the beam-like member at the mid-span of the link, which were employed to reduce the magnitude of the flexural response when they were activated by amplified signals emulating from two strain gage sensors bonded to the surfaces of the piezoceramic actuators. The authors believe that this is the first paper to present experimental results for a linkage featuring this class of smart materials, and these results will hopefully motivate more theoretical studies on mechanism systems fabricated from this class of biomimetic materials. The results from this preliminary investigation add credibility to the proposition that this new generation of macroscopically smart materials will have a significant role to play in the design of the next generation of machines and mechanisms.
Computational Techniques for Finite Element Method Based Kineto-Elastodynamic Analysis of Mechanisms
Authors: Mahna Vinod K. , Asnani Nanik T.
Published: March 2021

The aim of computational techniques employed for the kineto-elastodynamic analysis of mechanisms is to evaluate the strain induced at any prescribed location in an elastic constituent link of the mechanism. The problem to be grappled is one of multi-degree-of-freedom coupled differential equation and is amenable to its solution by the modal analysis and numerical integration techniques. This formidable problem calls for imposition of boundary conditions and inter-link compatibility requirements, assembly of elemental matrices, incorporation of geometric stiffness matrix, evaluation of non-symmetric coupling term matrices, elimination of rigid-body degrees of freedom, transformation of local constraints pressed upon by the kinematic joints to the global frame before the stage gets propitious to embark upon the solution procedure. This paper enlarges upon the computational aspects involved in the kineto-elastodynamic analysis of mechanisms using finite-element method.
Stress Analysis and Optimal Cross-Section Design of Noncircular Spring Wire
Authors: Le Li , Lin Yuyi
Published: March 2021

The stress distribution of noncircular cross sections of straight rods and helical springs is studied. The Poisson equation describing the torsional stress on an irregular region is solved by using a special finite difference operator. The stress distribution of several cross sections of both straight rods and helical springs are obtained numerically and then verified by comparison to available analytical solutions. Using this numerical approach, the optimal ovateness values as a function of the spring indices is found. Moreover, a new cross section, which is a modified polynomial of degree four, having more uniform stress distribution is discovered.
Optimal Design of Elastic Linkage Mechanisms With Multi-Frequency Constraints
Authors: Xianmin Zhang , Yunwen Shen , Hongzhao Liu , Weiqing Cao
Published: March 2021

The paper presents a finite element method for minimum weight design of flexible mechanisms with multiple frequency constraints and upper and lower bound constraints on the design variables. The design algorithm developed in this paper is formulated in terms of the Kuhn-Tucker optimality criterion, in which two damping factors are introduced to guarantee the algorithm possesses good stability and convergence. The first and second order design sensitivity analysies of eigenvalues are presented and the values of the damping factors α and β are recommended. Results of three numerical examples show that the algorithm is stable and the optimal design can be obtained in lsee than fifteen iterations.
A General Approach to the Determinations of Planar and Spatial Cam Profiles
Authors: Tsay Der Min , Wei Hsien Min
Published: March 2021

A systematic development for the theory of envelopes with proof is presented. It offers a simple and general procedure to determine the planar and spatial cam profiles. Based on the theory, a planar or spatial cam profile is defined as the envelope of its follower surfaces represented in parametric form in different relative positions of the cam and the follower. The procedure is illustrated by determining the two-dimensional and three-dimensional cam profiles with analytical expressions. To show its accuracy and effectiveness, the results are then compared to those obtained by an earlier approach using the screw theory.
A Finite Element Formulation of Flexible Slider Crank Mechanism Using Local Coordinates
Authors: Fallahi Behrooz , Lai S. , Venkat C.
Published: March 2021

The need for higher productivity has lead to the design of machines operating at higher speeds. At high speed the rigid body assumption is no longer valid and the links should be considered flexible. In this work a method which is based on Modified Lagrange Equation for modeling flexible mechanism is presented. The method posses a more computational efficiency for not requiring the transformation from the local coordinate system to the global coordinate system. Also an approach using the homogeneous coordinate for element matrices generation is presented. The approach leads to a formalism where the displacement vector is expressed as a product of two matrices and a vector. The first matrix is a function of rigid body motion. The second matrix is a function of rigid body configuration. The vector is a function of elastic displacement. This formal separation helps to facilitate the generation of element matrices using symbolic manipulations.
Motion of a Sphere on a Plane
Authors: Xu Yong-Xian , Kohli Dilip , Vezina Larry , Speranza Daniel R.
Published: March 2021

The motion of a sphere on a plane is a five degree-of-freedom motion. It consists of two independent translations of the geometric center of the sphere and three rotations corresponding to gyroscopic motion of the sphere. The trajectory of an imbalanced sphere on the plane depends on: (1) the physical and inertia properties of the sphere, (2) the initial conditions of motion, and (3) the friction between the sphere and the plane. To predict the trajectory of the sphere, a general Eulerian mathematical model is developed which takes into account these conditions. The mathematical model is verified through experimentation. For the first time, general characteristics of the translatory and rotatory motions of the imbalanced sphere with general inertia distribution are presented. The existence of the “break point” in the trajectory is illustrated by examples. The trajectory (track) of the contact point on the surface of the sphere is also analyzed.
Developing a Pedagogically Effective Programming Environment for Teaching Mechanism Design
Authors: Cheng Harry H.
Published: March 2021

The CH programming environment is an open system. Users can enhance the system through its various user interfaces. CH is specially designed for applications in mechanical systems engineering, although it is applicable to many other disciplines as well. Due to our interest in teaching, we intend to develop it as a pedagogically effective programming environment for teaching and student learning. CH has been successfully used as a teaching and learning tool for an undergraduate course, Computer-Aided Mechanism Design, at University of California, Davis in Fall 1993. In this paper we will present the CH programming environment and programming features developed for teaching and student learning. We will describe how a teaching tool-box is developed and used for teaching mechanism design. Source codes in the teaching tool-box are available to students so that they can study the software implementation of algorithms and modify the codes to solve the similar problems. Although the developed teaching tool-box is specific for instruction on mechanism design, the CH programming environment and ideas presented in this paper are general, and they are applicable to instructional improvement for a wide range of subjects in engineering.
Variable Stroke Piston Mechanism for Spark Ignition Engines
Authors: Elkholy A. H.
Published: March 2021

The concept of load control in internal combustion engines by eliminating the inlet throttle and replacing it by controlling the piston stroke has gained great publicity recently. Nevertheless, certain design parameters should be considered in order to make this concept worthwhile. In this study, an optimized mechanism for varying engine stroke has been introduced. A criteria based upon the use of complex numbers technique was used to analyze the mechanism kinematically and dynamically and the results were then verified using graphical solution. The mechanism was found to produce up to 56% stroke variation within the control actuator capabilities. The compression ratio was found unchanged (within ± 6%) which helps maintain steady combustion process. The entire mechanism is well tuned and no spark plug timing adjustment is required during stroke variation. The piston side thrust due to connecting rod angularities was found fairly low and should not impose any wear problems in the engine cylinder walls.
Effects of Design-Kinematic Parameters on Loading Capacity of Disc Cams With Translating Followers
Authors: Su Daizhong
Published: March 2021

The aim of this research is to investigate the effects of design parameters on disc cams’ loading capacity. A kinematic-Hertzian stress parameter (KHS) and a kinematic-elastohydrodynamic lubrication parameter (KEHL) are derived first, which reflect the combined contributions of kinematic parameters to Hertzian stress and elastohydrodynamic lubrication film thickness respectively, and then KHS and KEHL are analyzed against each design parameter. Based on the analysis, guidelines for cam mechanism design are proposed.
Theory of Isotropic Transmission for Tendon-Driven Manipulators
Authors: Ou Yeong-Jeong , Tsai Lung-Wen
Published: March 2021

This paper deals with the synthesis of the mechanical power transmission structure in tendon-driven manipulators. Based on the analysis of static force transmission from the actuator space to the end-effector space, a general theory is developed for the synthesis of tendon-driven manipulators with isotropic transmission characteristics. It is shown that an n-dof (degree of freedom) manipulator can possess these characteristics if it is made up of n+1 or 2n tendons and if its link lengths and pulley sizes are designed according to two equations of constraint. Two examples are used to demonstrate the theory. It is also shown that manipulators with an isotropic transmission structure do have more uniform force distribution among their tendons.
Solution to the Forward and Inverse Kinematic Equations Using Multilayer Back-Propagation Neural Network
Authors: Nagarjuna Phani K. , Soni Athamaram H.
Published: March 2021

The problem of inverse kinematics in Robotics, is a nonlinear mapping from a given cartesian coordinates to the desirable joint coordinates of the robot arm. It is found that an appropriately designed neural network can be trained to learn the non-linearity of the Inverse Kinematic Equation (IKE). We present an approach for solving the Forward Kinematic Equation (FKE) and the IKE by means of a Multi Layer Back-Propagation Neural Network (Rumelhart et al., 1986). The neural network approach is applied to a Two Degrees-of-Freedom (DOF) robot manipulator and the results are compared with those obtained using the analytical solution. The results obtained from the simulation of the neural network indicate a fairly accurate learning of the FKE and IKE by the Multi Layer Back-Propagation Neural Network.
Design and Simulation of Flexible Palletizing Systems
Authors: Tanasi Germán C. , Shirkhodaie Amir H. , Soni Athamaram H. , Quo Philip
Published: March 2021

The use of a simulation software in the study of a flexible automated material handling system such as a palletizing application constitutes a very useful tool for the field project engineer. FMCell provides a knowledgeable platform that allows the integrator to analyze diverse configurations in order to establish an optimum performance for the given requirements.

A feasibility study has been developed taking advantage of the features provided by this software. A typical scenario was selected, modeled and analyzed keeping always as an objective the flexibility and adaptability of the layout to diverse situations, such as variable type of loads and palletizing arrangements.
Development of an Autonomous Assembly Cell
Authors: Abu-Hamdan M. G. , El-Gizawy A. Sherif
Published: March 2021

The problem of implementing intelligent control structure in real world flexible assembly environment is discussed and the development of a sensory-based system is described. The new system possesses the ability to deal with assembly process environment as an autonomous one. The use of an integrated sensory devices not only enhances the accuracy of the assembly operations by providing measurements and information feedback, but also makes the entire system more robust in the presence of uncertainties due to operational errors.
The Technology of Language and How Advances Will Affect Product Modeling and Design
Authors: Povilus David S. , Conrad Jerome C.
Published: March 2021

Design and CAE are being influenced by a number of business factors that heighten the importance of communication, and, thus, language. Among these factors are: globalization of product and component markets, electronic commerce via EDI, competitive demands for shortened development cycles, and increased accountability for design through the entire product life cycle. Engineering management reflects these business factors in such trends as: outsourcing of design work on a global basis, subcontracting of construction and/or manufacturing engineering, and simultaneous engineering across disciplines.

This paper explores the oncoming revolution in language technology from the viewpoint of its potential effects on CAE. Some brief introductory observations are made on the importance and current status of language as it relates to design. Next, the philosophical and practical language barriers to further progress in object-oriented CAE are laid out. Finally, an agenda is proposed whereby these barriers can be overcome. Progress for CAE will be driven by the information needs of the end users of engineering’s products. This progress will be fed by technology advances and economic forces external to engineering design, yet it will take the form of a metalanguage unique to the field. Reaching our future aspirations for CAE will require the encouragement and cooperation of the commercial, professional, and governmental sectors, because the creation of a new language is a complex and costly proposition.
Is high-dimensional photonic entanglement robust to noise?
Authors: Zhu F. , Tyler M. , Valencia N. H. , Malik M. , Leach J.
Published: March 2021

High-dimensional entangled states are of significant interest in quantum science as they increase the information content per photon and can remain entangled in the presence of significant noise. The authors develop the analytical theory and show experimentally that the noise tolerance of high-dimensional entanglement can be significantly increased by a modest increase in the size of the Hilbert space. For example, doubling the size of a Hilbert space with a local dimension of d = 300 leads to a reduction in the threshold detector efficiencies required for entanglement certification by two orders of magnitude. This work is developed in the context of spatial entanglement in the few-photon limit, but it can easily be translated to photonic states entangled in different degrees of freedom. The authors also demonstrate that knowledge of a single parameter, the signal-to-noise ratio, precisely links measures of entanglement to a range of experimental parameters quantifying noise in a quantum communication system, enabling accurate predictions of its performance. This work serves to answer a simple question: “Is high-dimensional photonic entanglement robust to noise?” Here, the authors show that the answer is more nuanced than a simple “yes” or “no” and involves a complex interplay between the noise characteristics of the state, channel, and detection system.
LSD1 enzyme inhibitor TAK-418 unlocks aberrant epigenetic machinery and improves autism symptoms in neurodevelopmental disorder models
Authors: Baba Rina , Matsuda Satoru , Arakawa Yuuichi , Yamada Ryuji , Suzuki Noriko , Ando Tatsuya , Oki Hideyuki , Igaki Shigeru , Daini Masaki , Hattori Yasushi , Matsumoto Shigemitsu , Ito Mitsuhiro , Nakatani Atsushi , Kimura Haruhide
Published: March 2021

LSD1 inhibitor TAK-418 could be a therapeutic option for neurodevelopmental disorders via normalization of gene expression.
A natural killer’s hike through epigenetic landscapes
Authors: Rückert Timo , Romagnani Chiara
Published: March 2021

The transcription factor BCL11B guides NK cells along their differentiation trajectory (see the related Research Article by

Holmes
et al.

).
Disease ecology of wild fish: opportunities and challenges for linking infection metrics with behaviour, condition, and survival
Authors: Chapman Jacqueline M. , Kelly Lisa A. , Teffer Amy K. , Miller Kristi M. , Cooke Steven J.
Published: March 2021

Surmounting evidence supports that infectious agents play a critical role in shaping fish physiology, behaviour, and survival. The exclusion of disease-causing agents from fisheries research has resulted in major knowledge gaps that may limit the predictive capacity of ecological models. A major barrier in wild fisheries epidemiology is the logistical constraints associated with observing disease and obtaining samples from free-ranging fish, restricting the vast majority of research to laboratory studies or aquaculture facilities. For fisheries ecologists, including infectious agents can provide greater insight into observed phenomena, particularly with respect to fish physiology (e.g., metabolism), movement (e.g., migration rates), behaviour (e.g., habitat selection), personality (e.g., bold versus shy), and survival. Here we provide a brief introduction to the current understanding of disease ecology in wild fish and describe technological advances in both epidemiology and fisheries and aquatic sciences that can be used in tandem to create comprehensive studies of disease ecology in wild fishes. Combining nonlethal sampling and molecular genetic-based identification methods with field studies creates vast opportunities for innovative study designs that have the potential to address the true complexity of aquatic ecosystems.
Design and analysis of a low noise CMOS charge pump phase locked loop circuit
Authors: Chen Yanbo , Zhang Shubin
Published: March 2021

Phase Locked Loop (PLL) circuit plays an important part in electronic communication system in providing high-frequency clock, recovering the clock from data signal and so on. The performance of PLL affects the whole system. As the frequency of PLL increases, designing a PLL circuit with lower jitter and phase noise becomes a big challenge. To suppress the phase noise, the optimization of Voltage Controlled Oscillator (VCO) is very important. As the power supply voltage degrades, the VCO becomes more sensitive to supply noise. In this work, a three-stage feedforward ring VCO (FRVCO) is designed and analyzed to increase the output frequency. A novel supply-noise sensing (SNS) circuit is proposed to suppress the supply noise’s influence on output frequency. Based on these, a 1.2 V 2 GHz PLL circuit is implemented in 110 nm CMOS process. The phase noise of this CMOS charge pump (CP) PLL is 117 dBc/Hz@1 MHz from test results which proves it works successfully in suppressing phase noise.
Investigation of tunable Fano resonances based on the InSb metamaterials
Authors: Shi Chenyuyi , Peng Jun , Jin An , Leng Jin , He Xiaoyong , Cao Duo
Published: March 2021

Based on the hybrid semiconductive InSb metamaterials (MMs), we investigated the tunable Fano resonances in the terahertz regime, including the effects of carrier concentrations of InSb layer, environment temperatures and operation frequencies. The results manifested that an obvious Fano resonance was observed by using the heterostructure of InSb bars, the peak value of Fano resonance reached more than 0.97 with a high [Formula: see text]-factor of larger than 50. By changing the carrier concentrations of InSb layer, the propagation properties of semiconductor MM structures can be effectively modulated, the amplitude modulation of Fano resonance can reach more than 80%. The results are helpful for designing novel tunable terahertz devices with high [Formula: see text]-factor, e.g. modulators, sensors and antenna.
Dynamic Planning of Bicycle Stations in Dockless Public Bicycle-sharing System Using Gated Graph Neural Network
Authors: Chen Jianguo , Li Kenli , Li Keqin , Yu Philip S. , Zeng Zeng
Published: March 2021

Benefiting from convenient cycling and flexible parking locations, the Dockless Public Bicycle-sharing (DL-PBS) network becomes increasingly popular in many countries. However, redundant and low-utility stations waste public urban space and maintenance costs of DL-PBS vendors. In this article, we propose a Bicycle Station Dynamic Planning (BSDP) system to dynamically provide the optimal bicycle station layout for the DL-PBS network. The BSDP system contains four modules: bicycle drop-off location clustering, bicycle-station graph modeling, bicycle-station location prediction, and bicycle-station layout recommendation. In the bicycle drop-off location clustering module, candidate bicycle stations are clustered from each spatio-temporal subset of the large-scale cycling trajectory records. In the bicycle-station graph modeling module, a weighted digraph model is built based on the clustering results and inferior stations with low station revenue and utility are filtered. Then, graph models across time periods are combined to create a graph sequence model. In the bicycle-station location prediction module, the GGNN model is used to train the graph sequence data and dynamically predict bicycle stations in the next period. In the bicycle-station layout recommendation module, the predicted bicycle stations are fine-tuned according to the government urban management plan, which ensures that the recommended station layout is conducive to city management, vendor revenue, and user convenience. Experiments on actual DL-PBS networks verify the effectiveness, accuracy, and feasibility of the proposed BSDP system.
Experience-driven research on programmable networks
Authors: Kim Hyojoon , Chen Xiaoqi , Brassil Jack , Rexford Jennifer
Published: March 2021

Many promising networking research ideas in programmable networks never see the light of day. Yet, deploying research prototypes in production networks can help validate research ideas, improve them with faster feedback, uncover new research questions, and also ease the subsequent transition to practice. In this paper, we show how researchers can run and validate their research ideas in their own backyards---on their production campus networks---and we have seen that such a demonstrator can expedite the deployment of a research idea in practice to solve real network operation problems. We present
P4Campus
, a proof-of-concept that encompasses tools, an infrastructure design, strategies, and best practices---both technical and non-technical---that can help researchers run experiments against their programmable network idea in their own network. We use network tapping devices, packet brokers, and commodity programmable switches to enable running experiments to evaluate research ideas on a production campus network. We present several compelling data-plane applications as use cases that run on our campus and solve production network problems. By sharing our experiences and open-sourcing our P4 apps [28], we hope to encourage similar efforts on other campuses.
What do information centric networks, trusted execution environments, and digital watermarking have to do with privacy, the data economy, and their future?
Authors: Laoutaris Nikolaos , Iordanou Costas
Published: March 2021

What if instead of having to implement controversial user tracking techniques, Internet advertising & marketing companies asked explicitly to be granted access to user data by name and category, such as Alice→Mobility→05-11-2020? The technology for implementing this already exists, and is none other than the Information Centric Networks (ICN), developed for over a decade in the framework of Next Generation Internet (NGI) initiatives. Beyond named access to personal data, ICN's in-network storage capability can be used as a substrate for retrieving aggregated, anonymized data, or even for executing complex analytics within the network, with no personal data leaking outside. In this opinion article we discuss how ICNs combined with trusted execution environments and digital watermarking, can be combined to build a personal data overlay inter-network in which users will be able to control who gets access to their personal data, know where each copy of said data is, negotiate payments in exchange for data, and even claim ownership, and establish accountability for data leakages due to malfunctions or malice. Of course, coming up with concrete designs about how to achieve all the above will require a huge effort from a dedicated community willing to change how personal data are handled on the Internet. Our hope is that this opinion article can plant some initial seeds towards this direction.
Molecular Force Measurement with Tension Sensors
Authors: Fischer Lisa S. , Rangarajan Srishti , Sadhanasatish Tanmay , Grashoff Carsten
Published: March 2021

The ability of cells to generate mechanical forces, but also to sense, adapt to, and respond to mechanical signals, is crucial for many developmental, postnatal homeostatic, and pathophysiological processes. However, the molecular mechanisms underlying cellular mechanotransduction have remained elusive for many decades, as techniques to visualize and quantify molecular forces across individual proteins in cells were missing. The development of genetically encoded molecular tension sensors now allows the quantification of piconewton-scale forces that act upon distinct molecules in living cells and even whole organisms. In this review, we discuss the physical principles, advantages, and limitations of this increasingly popular method. By highlighting current examples from the literature, we demonstrate how molecular tension sensors can be utilized to obtain access to previously unappreciated biophysical parameters that define the propagation of mechanical forces on molecular scales. We discuss how the methodology can be further developed and provide a perspective on how the technique could be applied to uncover entirely novel aspects of mechanobiology in the future.
Effect of Indium on the Negative Difference Effect for Magnesium Alloy
Authors: Bao Tongyao , Hou Lifeng , Sun Junli , Liu Xiaoda , Du Huayun , Wei Huan , Wei Yinghui
Published: March 2021

The Mg-xIn (x = 0.5, 1, 1.5 wt.%) alloys exhibit the negative difference effect. This anomalous phenomenon was studied in 0.1 M NaCl solution using galvanostatic polarization testing and real-time hydrogen collection. Strong anomalous hydrogen evolution was observed in all three magnesium alloys, but the rate of hydrogen evolution at different anodic current densities decreased with the increased content of In element. It shows that adding indium to Mg can reduce the negative difference effect of Mg alloy. Assessment of the exchange current density for hydrogen evolution reaction supported the previously-proposed kinetic model. The exchange current density related to the hydrogen evolution reaction decrease with the increased content of In element, indicating the ability of magnesium alloys to support the cathodic reaction is weakened, and In element can effectively reduce the negative difference effect of magnesium alloy.