bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of Single-Input and Multiple-Output Port Mechanisms With Springs for Specified Energy Absorption
Authors: Jenuwine John G. , Midha Ashok
Published: March 2021

A means of synthesis of single-input and multiple-output port mechanisms for specified energy absorption is formulated for multiple precision points. The synthesis presented makes use of an extension of the loop closure method which includes expressions for energy absorption by linear spring elements. The configuration considered locates spring elements at two output ports of a multi-loop, planar mechanism. Economies realized for the symmetric mechanism are discussed for both one and two plane symmetry. Synthesis examples are included for both the general and symmetric mechanism. Special applications presented include synthesis of a constant force mechanism and synthesis of a mechanism suited to the energy absorption requirements of an automotive crashworthiness system.
Simulation of Mechanical Systems With Multiple Frictional Contacts
Authors: Wang Yin-Tien , Kumar Vijay
Published: March 2021

There are several applications in robotics and manufacturing in which nominally rigid objects are subject to multiple frictional contacts with other objects. In most previous work, rigid body models have been used to analyze such systems. There are two fundamental problems with such an approach. Firstly, the use of frictional laws, such as Coulomb’s law, introduce inconsistencies and ambiguities when used in conjunction with the principles of rigid body dynamics. Secondly, hypotheses traditionally used to model frictional impacts can lead to solutions which violate principles of energy conservation. In this paper these problems are explained with the help of examples. A new approach to the simulation of mechanical systems with multiple, frictional constraints is proposed which is free of such difficulties.
Multiple Flywheel Recuperation System
Authors: Marinov Philip , Pavlov Stefan
Published: March 2021

A multiple flywheel is studied for the purpose of storing and recuperating kinetic energy. The objective of the design of such systems is a maximum storage and recuperation of the stored energy. The dynamical models of the proposed and the conventional system are compared. Coefficients of storing and recuperating efficiency are introduced for demonstrating the advantages of the multiple flywheel system. An optimization is made regarding to maximum recuperating efficiency.
Systematic Synthesis and Applications of Novel Multi-Degree-of-Freedom Differential Systems
Authors: Kota Sridhar , Bidare Srinivas
Published: March 2021

A two-degree-of-freedom differential system has been known for a long time and is widely used in automotive drive systems. Although higher degree-of-freedom differential systems have been developed in the past based on the well-known standard differential, the number of degrees-of-freedom has been severely restricted to 2n. Using a standard differential mechanism and simple epicyclic gear trains as differential building blocks, we have developed novel whiffletree-like differential systems that can provide n-degrees of freedom, where n is any integer greater than two. Symbolic notation for representing these novel differentials is also presented. This paper presents a systematic method of deriving multi-degree-of-freedom differential systems, a three and four output differential systems and some of their practical applications.
Determination of the Shortest Crank in Four Position Synthesis: A Numerical Apporach
Authors: Song Shin-Min , Lu Fu-Hung , Chen Ning-Xin , Waldron Kenneth J.
Published: March 2021

The shortest crank of a four position synthesis can be determined by solving a statically determinate five-bar structure and a set of seven nonlinear equations have been proposed for this purpose. In this paper a numerical method which can directly solve the shortest crank is presented. It is found that a direct implementation of the original seven equations has two problems: many spurious solutions and poor numerical stability. And the spurious solutions are of the following two types: solutions with incorrect signs of angles and solutions with incorrect geometry. In order to solve the problems, a set of ten equations is developed and parameter perturbation method is applied. Furthermore, a set of eight equations is developed for better numerical stability. Both the ten and eight equations can eliminate the spurious solutions with incorrect geometry. Yet the spurious solutions with incorrect signs of angles can only be rectified after convergence. An automatic search algorithm is included to automatically search the shortest crank in the solution space. Many examples are given to illustrate this numerical approach.
Application of the Theory of Envelope to the Determination of Camoid Profiles With Translating Followers
Authors: Tsay Der Min , Hwang Guan Shyong
Published: March 2021

A new, simple procedure employing the theory of envelope for a family of surfaces with two independent parameters to determine the profiles of camoids with translating spherical followers is presented. Given the follower motion program, the method enables the camoid surface coordinates to be easily generated in an analytical expression. The results are then compared to those obtained by utilizing the principle of contact point between the camoid and the follower surfaces. The pressure angle is analyzed, and the cutter paths required in the machining process are also produced. A numerical example is given to illustrate the application of the approach.
Graphical Synthesis for Limit Positions of a Four-Bar Mechanism Using the Triangle Inequality Concept
Authors: Norton Tony W. , Midha Ashok , Howell Larry L.
Published: March 2021

An innovative methodology is presented for a set of synthesis problems in which the mobility angle between limit positions of a side link of a four-bar mechanism is necessarily prescribed. The principles used in synthesis are derived from a graphical interpretation of the triangle inequality concept. The derived principles give valuable insight to the solution space by dividing it into two separate regions. One region yields only Grashofian mechanisms, and the other region yields only Non-Grashofian mechanisms. This information gives the designer a method for generating all possible mechanisms which satisfy the limit position and mechanism type constraints. A major advantage of the graphical technique is that it uses simple geometric objects, and therefore it can be easily implemented on most CAD packages. Several examples are used to demonstrate the concepts.
Criteria for the Design of High Efficiency Planocentric Transmissions
Authors: Jáuregui Juan Carlos , Sansalvador Rodrigo López
Published: March 2021

In this paper, the design criteria for high efficiency planocentric transmissions is presented. The space solution of a single stage planocentric transmission is limited by geometric constraints. These constraints are produced basically by the interference between pinion teeth and gear teeth. Special interest is focused on the interferences of internal gears and a detailed analysis of the influence of teeth parameters, such as addendum coefficient and pressure angle, is included. Conclusions are drawn from the analysis of the interferences and a design criteria is outlined. It was found that the space solution can be wider if pinion and gear are designed with stub teeth and high pressure angle.
On the Dynamic Analysis of Roller Chain Drives: Part I — Theory
Authors: Veikos Nicholas M. , Freudenstein Ferdinand
Published: March 2021

A generally applicable, computer-aided procedure has been developed for the dynamic analysis of roller chain drives. This approach addresses important factors of chain dynamic behavior such as impact, discontinuities in span length, chain elasticity, coupling between longitudinal and transverse motions, as well as coupling between motion and boundary conditions. The procedure has been used to study various chain configurations. The results show good agreement with experimental observations and indicate some general trends, which provide additional insight into the dynamic behavior of these systems.
On the Dynamic Analysis of Roller Chain Drives: Part II — Case Study
Authors: Veikos Nicholas M. , Freudenstein Ferdinand
Published: March 2021

Part I of this paper (5) summarized the previous work and has described the theoretical and computational aspects of a computer-aided procedure which has been developed by the authors for the dynamic analysis of roller chain drives. Lagrange’s equations of motion have been derived by assuming the roller chain to behave as a series of masses lumped at the roller centers and connected by bars of constant axial stiffness. The equations of motion are solved in the time domain until steady state conditions are achieved.
Use of Resultant in the Dimensional Synthesis of Linkage Components: Motion Generation With Prescribed Timing
Authors: Lin Chuen-Sen , Jia Bao-Ping
Published: March 2021

Resultant theory is applied to derive closed-form solutions for the dimensional synthesis of linkage components for a finite number of precision positions for motion generation with prescribed timing. The solutions are in forms of polynomial equations of the exponential of a single unknown angular displacement. The degree of the derived polynomial depends on the number of links in the linkage component and the number of precision positions to be synthesized for, or the number of compatibility equations. The resultant theory is discussed in detail, and the procedure for the derivation of resultant polynomials is demonstrated. This paper shows that, for the case of two compatibility equations, the solution is a six-degree polynomial. For the case of three compatibility equations, the solution is a fifty-fourth degree polynomial. The Bernshtein formula is applied to check the exact number of solutions of the original system of polynomial equations and to verify the validity of the derived resultant polynomials. An algorithm is also proposed for screening out extra solutions which may be generated through the solution process.
Constrained Optimization of Multi-Degree-of-Freedom Mechanisms for Near-Time Optimal Motions
Authors: Sundar Satish , Shiller Zvi
Published: March 2021

This paper presents a design method of multi-degree-of-freedom mechanisms for near-time optimal motions. The design objective is to select system parameters, such as link lengths and actuator sizes, so as to minimize the optimal motion time of the mechanism along a given path. The exact time optimization problem is approximated by a simpler procedure that maximizes the acceleration near the end points. Representing the directions of maximum acceleration with the acceleration lines, and the reachability constraints as explicit functions of the design parameters, we transform the constrained optimization to a simpler curve fitting problem that can be formulated analytically. This allows the use of efficient gradient type optimizations, instead of the pattern search optimization that is otherwise required. Examples for optimizing the dimensions of a five-bar planar mechanism demonstrate close correlation of the approximate with the exact solutions, and an order of magnitude better computational efficiency than the previously developed unconstrained optimization methods.
A Unified Theory for Kinematic Synthesis
Authors: James Paul A. , Roth Bernard
Published: March 2021

In this paper we derive an analytic method for obtaining infinitesimal kinematic synthesis results as a limiting process from finitely-separated position kinematics. Expanding on previous work, we extend the unified theory to include spatial kinematic synthesis and we present a new numerical method. These new methods serve to unify finite, infinitesimal, and hybrid kinematic synthesis into one theory for kinematic synthesis.
A Singularity-Free Penalty Formulation for the Dynamics of Constrained Multibody Systems
Authors: Avello A. , Bayo E.
Published: March 2021

In a singular position, the number of degrees of freedom of a mechanism instantaneously increases, which is detected by a sudden loss of rank in the jacobian matrix. This rank-deficiency causes the failure of the classical dynamic formulations. The enforcement of the constraints through a penalty method leads to an attractive and efficient dynamic formulation that, in addition, can be used at singularities. This formulation leads to a symmetric and positive definite matrix whose rank does not depend on the rank of the jacobian and thus is ideally suited for singular positions. A refinement of this approach is achieved through an augmented Lagrangian method. A simple example and two dynamic simulations show the effectiveness of the formulation.
Using Singular Value Decomposition in the Analysis of Over and Underconstrained Mechanisms
Authors: Gutkowski L. J.
Published: March 2021

A method for analyzing mechanisms using Singular Value Decomposition is presented. This approach provides a general technique in which all mechanisms (including planar ones) can be analyzed as spatial without numerical consequences or special case procedures. This technique is also useful for dealing with idle degrees-of-freedom automatically.
Dynamics of a Flexible Closed-Chain Manipulator
Authors: Giovagnoni Marco
Published: March 2021

An approach to flexible linkage analysis is presented Requirements are defined for a correct definition of the rigid-link reference mechanism, from which small displacements are measured. The equations of motion are obtained applying the principle of virtual work. Some terms in both the real and the virtual components are neglected according to the small displacement assumption. A numerical example is presented: a flexible 3 d.o.f. manipulator is considered, the input-torque vector is defined, and the proposed approach is applied to simulate the system response.
Linearization and Jacobian Evaluation of the Dynamics of Closed-Chain Mechanical Systems
Authors: Lin Tsung-Chieh , Yae K. Harold
Published: March 2021

This paper presents an analytical/numerical method for linearizing the equations of motion and evaluating the system Jacobian matrices of mechanical systems with closed chains. The linearization algorithm developed here first identifies and linearizes basic recursive kinematic relationships and then applies the chain rule to the derivation of the equations of motion under the framework of recursive formulation. This method can be incorporated into formulating recursive equations of motion for general multibody dynamic systems, to handle large scale systems. Since no numerical differentiation is used in the proposed algorithm, its accuracy is comparable to symbolic, closed-form linearization. Moreover, without the need of repetitious computation to select proper perturbation quantities, this method is computationally more efficient than the finite difference method.
Dynamic Models of Robots With Linkage Structures
Authors: Wang Shin-Liang
Published: March 2021

A systematic approach to formulate the dynamic model of a robot with a linkage structure is presented. A dynamic model similar to that of a serial link robot can be obtained with respect to active joints only. The kinetic energy can be formulated from the Newton-Euler equation, and passive joint rates can be eliminated using loop closure equations. Inertial terms can be derived from the kinetic energy; gravitational terms from the potential energy and Lagrangian equation; and the Coriolis and centrifugal terms from the inertial terms and the Lagrangian method. This approach is very efficient for simple mechanisms, most likely to be used in linkage robots.
Attitude Control Methods for Walking Machines
Authors: Gonzalez de Santos Pablo , Nagy Peter V. , Whittaker William L.
Published: March 2021

In this paper four different methods for body attitude control are evaluated for their effectiveness. One of them uses all axes to level the body. The other three utilize only the vertical axes. The difference among these methods is the amount of geometric information used to calculate the intended motion and resultant differences in the motion of the machine when applying these methods. Simulations and experiments on the AMBLER walking machine were used to evaluate these differences. The all-axes attitude control method considers complete geometry thereby avoiding foot slippage, but this is at the cost of higher energy expenditure to servo three motions per leg.
On the Analysis and Optimization of a Basic Variable-Ratio Drive: The Paper Cutter
Authors: Freudenstein Ferdinand , Chen Hong Jen
Published: March 2021

A mechanical analysis has been developed for the forces generated in paper cutting as a function of blade geometry. This in turn permits the optimization of cutter geometry for various design objectives and provides insight into the subtleties of what might at first appear to be one of the simplest mechanisms of mankind.
Dynamics of Open and Closed Chain Spherical Mechanisms Using Quaternion Coordinates
Authors: Dooley J. R. , McCarthy J. M.
Published: March 2021

This paper presents a general technique for deriving the equations of motion for any open or closed chain spherical mechanism. The technique uses quaternion coordinates to represent the position of each rigid body in the mechanism. Thus, if there are n moving bodies in the chain, there are 4n generalized coordinates in the equations of motion. The use of quaternion coordinates results in standardized quadratic constraint relations representing the hinged connections between bodies in the mechanism. These constraint equations augment the equations of motion. This technique has two important features. First, it is specifically adapted to spherical mechanisms and presents all positions as rotations. Second, the quadratic form of the constraint equations simplifies the computation of velocities and accelerations compatible with the constraints. As an example the equations of motion for a closed six bar spherical chain are derived.
Topological Characteristics and Automatic Generation of Structural Synthesis of Spatial Mechanisms: Part I — Topological Characteristics of Mechanical Networks
Authors: Yang Ting-Li , Yao Fang-Hua
Published: March 2021

This paper presents a new viewpoint about structural composition of spatial kinematic chains; single-opened chains are regarded as basic structural units of mechanisms. The constraint characteristics (the constraint factors, Δj) of single-opened chains and the constraint characteristics (the coupled degree, κ and the κ-algorithm) of mechanical networks are presented. Thus a kinematic chain with ν independent loops is regarded to be composed of one basic link and ν single-opened chains in regular sequence.

The above mentioned topological characteristics are used for setting up a new unified model for structural analysis and synthesis, kinematics and dynamics of spatial mechanisms.
Topological Characteristics and Automatic Generation of Structural Synthesis of Spatial Mechanisms: Part II — Automatic Generation of Structural Types of Kinematic Chains
Authors: Yang Ting-Li , Yao Fang-Hua
Published: March 2021

Based on the single-opened chain constraints and the network topological characteristics of mechanisms, a powerful new method for structural synthesis of spatial kinematic chain with plane and nonplane linear graphs has been developed. This permits the development of a highly efficient and completely automatic program for the computer-generated enumeration of structural types of mechanisms. The method is illustrated by applying to the case of kinematic chains with up to six independent loops on a personal computer.
On the Nomenclature and Classification of Compliant Mechanisms: Abstractions of Mechanisms and Mechanism Synthesis Problems
Authors: Midha Ashok , Norton Tony W. , Howell Larry L.
Published: March 2021

A compliant mechanism is one which gains all or part of its mobility from the relative flexibility of its members rather than from rigid-body joints only. Compliant mechanisms offer clear advantages, such as need for fewer parts, less wear, noise and backlash due to clearances, when compared to rigid-body mechanisms performing similar functions. This important field is expected to undergo significant growth as materials with superior properties are developed. In the development of compliant mechanisms, the establishment of nomenclature and classification is of primary importance. This paper discusses common representations, i.e. names and diagrams, for a compliant mechanism. Names and diagrams will be shown to be similar because they represent “abstractions” of the same mechanism. The concept of “levels of abstraction” is introduced, and common levels of abstraction are identified. The relevance of this concept to the naming of mechanisms is shown by applying it to both rigid-body and compliant mechanism examples. Nomenclature is proposed for several of the common levels of abstraction, and issues involved in naming mechanisms are discussed. Finally, a discussion of synthesis types is presented, as are the advantages, disadvantages, and issues involved in the synthesis of a compliant mechanism.
The Transmissivity and Manipulability of Spatial Mechanisms
Authors: Tsai Ming J. , Lee Hong W.
Published: March 2021

A method of evaluating the transmission performance for spatial mechanisms is developed using the reciprocity of screws. The actual transmission performance of a spatial mechanism should be composed of two parts: the ability of the output that can be effectively generated by the mechanism is called the “transmissivity,” and the ability of the input that can be effectively absorbed into the rest part of the mechanism is called the “manipulability.” A more generalized index for the total transmission performance of spatial mechanisms is then defined and illustrated by some spatial four-link mechanisms.
Dynamic Characteristics for a Planar Two-Link Flexible Multibody System Including the Gravity Effects
Authors: Wiens G. J. , Tsai H.
Published: March 2021

This paper addresses modeling issues that arise in the formulation of the equations of motion for the flexible multibody mechanical systems intended for space applications and designed according to ground test results. A planar multibody system consisting of two flexible links interconnected by two revolute joints and a payload at its free end is proposed for the investigations. In addition to the gravity and transverse deflections (most common two conditions adopted for the research in this field), the foreshortening effects, the axial deflections and the work done by the system’s own weight on the elastic deflections are also taken into consideration. Since the slender link assumption is made, the Euler-Bernoulli Beam theory is considered sufficient and satisfactory for describing the behavior of the deformed link components. The Lagrangian formulation in conjunction with assumed displacement field method is then implemented to develop the equations of motion for the system. After achieving the analytical model for the system, a linearization about various system configurations transforms the fully coupled nonlinear differential equations into standard eigenvalue problems. In doing so, the roles played by gravity, foreshortening and system’s own weight (‘weight-load’) on the dynamic behavior of the system undergoing ground testing are examined. For analysis, the fundamental frequency of the system is chosen as a measurement index. Finally, parametric studies focusing on the mass properties of payload, lower and upper links, and actuators are undertaken to address the stability problems. Results indicate that the ‘weight-load’ exhibits interesting effects on the ‘foreshortening and stability’, hence, merits further investigation.
A New Analytical Approach for the Determination of the Transient Response in Elastic Mechanisms
Authors: Xu T. , Lowen G. G.
Published: March 2021

Recent work on multi-regime per cycle machinery has shown that for such systems the transient response of the link deflections, which is governed by the homogeneous solution to a Hill-type differential equation, cannot be neglected in a meaningful simulation. Based on mathematical work by E.T. Whittaker, a new analytical approach for obtaining such transient responses is given. It is achieved by the determination of the characteristic exponent in the stable regions of the Floquet solution to the Hill’s equation involved. This technique is applied to a specific elastic mechanism. Several sample computations show that the transient response may vary from near-periodic to totally aperiodic.
Efficiency of Methods for Kinematic Analysis Using the Algebra of Rotations
Authors: Fenton R. G. , Xi F.
Published: March 2021

The algebra of rotations is an alternative method for describing rigid body rotations. It can be efficiently used in the kinematic analysis of robots. One of the basic problems of the algebra of rotations is to determine the resultant sum of a number of sequential joint rotations. For this calculation, four new methods, in addition to the two methods already available in the literature, are proposed in this paper. The six methods are then compared analytically and numerically on the basis of the computational efficiency. The limitations to each of the methods are also discussed. It is found that the equivalent Rodrigues parameter method is the most efficient. However, the equivalent Euler parameter method is the preferred method for use since it is infinity free, initial vector independent and reasonably efficient.
On the Use of the Canonical Equations of Motion for the Dynamic Analysis of Constrained Multibody Systems
Authors: Bayo E. , Jimenez J. M.
Published: March 2021

We investigate in this paper the different approaches that can be derived from the use of the Hamiltonian or canonical equations of motion for constrained mechanical systems with the intention of responding to the question of whether the use of these equations leads to more efficient and stable numerical algorithms than those coming from acceleration based formalisms. In this process, we propose a new penalty based canonical description of the equations of motion of constrained mechanical systems. This technique leads to a reduced set of first order ordinary differential equations in terms of the canonical variables with no Lagrange’s multipliers involved in the equations. This method shows a clear advantage over the previously proposed acceleration based formulation, in terms of numerical efficiency. In addition, we examine the use of the canonical equations based on independent coordinates, and conclude that in this second case the use of the acceleration based formulation is more advantageous than the canonical counterpart.
Mass Flow and Derivative Moment of Inertia Flow in Planar (Geared) Linkages
Authors: Ye Zhonghe , Smith M. R.
Published: March 2021

The paper describes a method for the determination of the conditions for the complete shaking force and shaking moment balancing of planar linkages, including geared linkages, with revolute and prismatic joints. The conditions may be written down without the need for any kinematic analysis of the linkage by the application of two new concepts. These are the concept of mass flow for complete shaking force balance and the concept of derivative moment of inertia flow for complete shaking moment balance, the second of which is described here for the first time. A number of examples demonstrate the power of the method.
Design of an Epicyclic Transmission for Speed Control of a Turbine-Generator System
Authors: Barman Indranil , Flugrad Donald R.
Published: March 2021

An improved speed control method is proposed for a turbine-generator system. Whereas the present method employs a steam valve to control the flow of steam according to the desired output, the proposed system uses an epicyclic gear train to provide fine control of the speed, while coarse control is still maintained through the steam valve. The systematic design of such a gear train is the objective of this project. Two configurations are considered as suitable candidates. After the transmissions are analyzed to obtain the speed and torque relations, the dynamic equations of motion and control equations for the systems are derived for simulation purposes. The simulations are then conducted for various load cases and parameter values to determine a suitable design for application in the power industry. The final configuration allows constant generator output speeds to be reliably maintained in the face of significant load disturbances.
Dynamic and Stress Analyisis of Spatial Flexible Mechanical Systems
Authors: Kremer J. M. , Shabana A. A. , Widera G. E. O.
Published: March 2021

This investigation concerns itself with the dynamic and stress analysis of thin, laminated composite plates consisting of layers of orthotropic laminae. It is assumed that the bonds between the laminae are infinitesimally thin and shear nondeformable. The finite element formulation presented is sufficiently general to accept an arbitrary number of layers and an arbitrary number of orthotropic material property sets. In the dynamic formulation presented, the laminae is assumed to undergo large arbitrary rigid body displacements and small elastic deformations. The nodal shape functions of the laminae are assumed to have rigid body modes that need to describe only large rigid body translations. Using the expressions for the kinetic and strain energies, the lamina mass and stiffness matrices are identified. The nonlinear mass matrix of the lamina is expressed in terms of a set of invariants that depend on the assumed displacement field. By summing the laminae kinetic and strain energies, the body mass and stiffness matrices are identified. It is shown that the body invariants can be expressed explicitly in terms of the invariants of its laminae. Numerical examples of a spatial RSSR mechanism demonstrate the use of the present formulation.
Redundant Robot: A Dynamic Performance Point of View
Authors: Marchis Vittorio , Sinatra Rosario
Published: March 2021

Redundant robots find important applications in non structured environment, particularly in presence of obstacles.

The number of degree of freedom (DOF) allow a choice of the configuration over range, even when the path has been planned and the constraints have been taken into account.

Optimization of the time history, to be planned for the robot, can be achieved with respect to several objective functions.

Following to a previous work by the Authors, the present paper analyzes the vibration eigenfrequencies, and their oscillation principal directions applied to a plane 3R manipulator, over its entire workspace.

A dynamic performance map, correlated to the robot geometrical parameters, has been calculated via Monte Carlo method.
PDES/STEP: A Status Report
Authors: Ryan Steven A.
Published: March 2021

This status report provides a current overview of the work that is progressing toward the development of an international Standard for the Exchange of Product model data (STEP). STEP has the potential for revolutionizing the exchange of product definition data. The current state of the art in product data exchange requires knowledge of both the sending and receiving system in order to expect a reliable exchange to occur. The basic premise that STEP is built upon is to support the exchange and sharing of product model data without the need to know the sending or receiving system. The first release of STEP as a Draft International Standard will occur in 1992. The capability of that release will provide a strong basis for system designers and integrators to develop STEP compliant products that can support a significant portion of the product definition data that is exchanged today between and within businesses.
Use of PDES in Group Technology Applications for Electronics
Authors: Harhalakis G. , Kinsey A. , Minis I.
Published: March 2021

A novel application of the PDES standard for automated group technology (GT) code generation is presented. The study focuses on microwave modules (MWM’s), which include a mechanical ground plane with machined features, as well as electrical artwork and electronic components. Several modifications and enhancements were made to the Layered Electrical Product information model of the PDES standard in order to capture the particular characteristics of MWM’s. The modified PDES model was implemented using the ORACLE relational database, and served as the primary input to the automated GT code generation system developed at the University of Maryland. The principle difficulties encountered using PDES in our work are discussed, including: (i) lack of a proper feature hierarchy, (ii) limiting supertype-subtype specifications, and (iii) complications in implementing the LEP model to a relational database schema.
Environment for Application Software Integration and Execution
Authors: Jones Kennie H. , Randall Donald P. , Rowell Lawrence F. , Gates Raymond L. , Nichols Chris M. , Williams S. Blake
Published: March 2021

The Environment For Application Software Integration and Execution (EASIE) is a methodology and a set of software utility programs developed at the NASA Langley Research Center for coordinating the use of engineering design and analysis computer programs. Under user direction, EASIE controls the execution of independently developed programs and manages the flow of data to and from a common relational data base in order to accomplish design or analysis objectives.

The process is highly automated. For example, a utility program generates a DATA DICTIONARY, describing the contents of the data base and the various subsets of data used by the application programs. Other utilities automatically generate FORTRAN or C subroutines to link the application programs with the database or to pre- and post-process the data. EASIE is also “user friendly,” providing “windows” into the data base to view subsets of the data and the means to modify the data at any time A key feature is the degree of independence it provides to the programmer and user from the details of the operating system and Data Base Management System.

EASIE has been used successfully in the integration of several design systems at Langley and within the aerospace industry. This paper discusses the application of EASIE to these specific systems, emphasizing the advantages it has provided to both programmers and users. Significant improvements made as a result of these experiences will also be discussed.
Ion implantation in β-Ga2O3: Physics and technology
Authors: Nikolskaya Alena , Okulich Evgenia , Korolev Dmitry , Stepanov Anton , Nikolichev Dmitry , Mikhaylov Alexey , Tetelbaum David , Almaev Aleksei , Bolzan Charles Airton , Buaczik Antônio , Giulian Raquel , Grande Pedro Luis , Kumar Ashok , Kumar Mahesh , Gogova Daniela
Published: March 2021

Gallium oxide, and in particular its thermodynamically stable β-Ga2O3 phase, is within the most exciting materials in research and technology nowadays due to its unique properties. The very high breakdown electric field and the figure of merit rivaled only by diamond have tremendous potential for the next generation “green” electronics enabling efficient distribution, use, and conversion of electrical energy. Ion implantation is a traditional technological method used in these fields, and its well-known advantages can contribute greatly to the rapid development of physics and technology of Ga2O3-based materials and devices. Here, the status of ion implantation in β-Ga2O3 nowadays is reviewed. Attention is mainly paid to the results of experimental study of damage under ion irradiation and the properties of Ga2O3 layers doped by ion implantation. The results of ab initio theoretical calculations of the impurities and defect parameters are briefly presented, and the physical principles of a number of analytical methods used to study implanted gallium oxide layers are highlighted. The use of ion implantation in the development of Ga2O3-based devices, such as metal oxide field-effect transistors, Schottky barrier diodes, and solar-blind UV detectors, is described together with systematical analysis of the achieved values of their characteristics. Finally, the most important challenges to be overcome in this field of science and technology are discussed.
Ipsilateral Proprioceptive Neuromuscular Facilitation Hamstring Stretching Results in Bilateral Improvements in Flexibility: Study Results and Clinical Application
Authors: Denegar Craig R. , Gray Justina
Published: March 2021

Proprioceptive neuromuscular facilitation (PNF) stretching of the hamstrings improves flexibility but requires assistance from a clinician or partner. The original intent of our work was to assess the efficacy of self-assisted PNF hamstring stretching using a commercially available device. The authors observed improved flexibility in the stretched leg and, to a lesser extent, in the contralateral leg. While this was at first simply interesting, the finding became clinically relevant in the subsequent application in the care of a patient with low-back pain with radiating pain. This report provides study data and describes the translation of study findings into the care of a patient in a clinical setting.
A tumor-specific mechanism of T
reg
enrichment mediated by the integrin αvβ8
Authors: Seed Robert I. , Kobayashi Kenji , Ito Saburo , Takasaka Naoki , Cormier Anthony , Jespersen Jillian M. , Publicover Jean , Trilok Suprita , Combes Alexis J. , Chew Nayvin W. , Chapman Jocelyne , Krummel Matthew F. , Lou Jianlong , Marks James , Cheng Yifan , Baron Jody L. , Nishimura Stephen L.
Published: March 2021

Tumor cells expressing integrin αvβ8 activated latent TGF-β on T cells, inducing T
reg
enrichment and tumor immunosuppression.
Uplifted marine terraces on Santa Catalina Island, California, USA
Authors: McInnis Margarita , Pinter Nicholas
Published: March 2021

Marine terraces are widespread along California's coastline, including on all of the Channel Islands, with the possible exception of Santa Catalina. For over a century, the origins of subhorizontal surfaces and gravel deposits on Santa Catalina have been debated, with recent suggestions that Santa Catalina has no marine terraces and is subsiding. We mapped, measured, and described terrace deposits on Santa Catalina Island, including both in situ deposits and distributed gravel float. Rounded gravels and cobbles, locally pholad-bored, are present as float across low-relief surfaces in the Little Harbor area. We also mapped and described the Eagles Nest Gravels, an ∼8-m-thick package overlying a broad bedrock-cut platform at ∼200 m elevation and dipping 3.2° northward. The Eagles Nest Gravels contain rounded cobbles and boulders, many of which contain pholad borings. Two other platforms are inferred from concordant gravels with similar orientations but at lower elevations. Terrace deposits on Santa Catalina truncate underlying lithological units, including a narrow band of fossiliferous Miocene to Pliocene sands. Terrace deposits and gravel lag on Santa Catalina closely resemble older terrace deposits on other California Channel Islands. The terraces on Santa Catalina Island remain undated but document at least 200 m of net uplift, similar to the elevations of undated terraces on the other Channel Islands. While the timing of uplift of Santa Catalina is unclear, analysis of terrace deposits in the Little Harbor area confirms their marine origin and settles the debate regarding the presence of marine terraces on Santa Catalina Island.
Supplemental Material: Ferric iron triggers greenalite formation in simulated Archean seawater
Authors: Hinz Isaac , Johnson Jena , al. et
Published: March 2021

A complete description of the experimental methods, analytical techniques, and supporting data and information regarding mineral identifications.
Pharmacologically treated diabetes and hospitalization among older Norwegians receiving homecare services from 2009 to 2014: a nationwide register study
Authors: Fismen Anne-Siri , Igland Jannicke , Teigland Tonje , Tell Grethe Seppola , Ostbye Truls , Haltbakk Johannes , Graue Marit , Birkeland Kare I , Peyrot Mark , Iversen Marjolein Memelink
Published: March 2021

Introduction

The aim was to assess whether annual hospitalization (admissions, length of stay and total days hospitalized) among persons >65 years receiving home care services in Norway were higher for persons with diabetes than those without diabetes. Given the growing prevalence of diabetes, this issue has great importance for policy makers who must plan for meeting these needs.

Research design and methods

Data were obtained from national Norwegian registries, and the study population varied from 112 487 to 125 593 per calendar year during 2009–2014. Diabetes was defined as having been registered with at least one prescription for blood glucose lowering medication. Overall and cause-specific hospitalization were compared, as well as temporal trends in hospitalization. Hospitalization outcomes for persons with and without diabetes were compared using log-binomial regression or quantile regression, adjusting for age and gender. Results are reported as incidence rate ratios (IRRs).

Results

Higher total hospitalization rates (IRR 1.17; 95% CI 1.12 to 1.22) were found among persons with, versus without, diabetes, and this difference remained stable throughout the study period. Similar reductions over time in hospital length of stay were observed among persons with and without diabetes, but total annual days hospitalized decreased significantly (p=0.001) more among those with diabetes than among those without diabetes.

Conclusions

Among older recipients of home care services in Norway, diabetes was associated with a higher overall risk of hospitalization and increased days in the hospital. Given the growing prevalence of diabetes, it is important for policy makers to plan for meeting these needs.
Predictors of controlled prescription drug non-medical and lifetime use among patients accessing public mental health services in Uganda: a cross-sectional study
Authors: Kamba Pakoyo Fadhiru , Mulangwa John , Kageni Peter , Balikuna Sulah , Kengo Allan , Mutamba Brian Byamah , Sewankambo Nelson , Adome Richard Odoi , Byakika-Kibwika Pauline
Published: March 2021

Objectives

We determined the prevalence of controlled prescription drug (CPD) non-medical and lifetime use and their predictors among patients at three public psychiatric clinics in Uganda to identify missed care opportunities, enhanced screening priorities, and drug control needs.

Methods

A cross-sectional survey of 1275 patients was performed from November to December 2018. Interviewer-administered semi-structured questionnaires, desk review guide and urine drug assays were employed. Questionnaire recorded CPD non-medical and illicit drug use history from patients’ files, CPD lifetime use and risk factors. Desk review guide recorded recently prescribed drugs in patients’ files to corroborate with urine assays. Predictors were analysed by multivariate logistic regression.

Results

From desk review, 145 (11.4%) patients had history of CPD non-medical use and 36 (2.8%) had used illicit drugs. Of 988 patients who provided urine, 166 (16.8%) self-medicated CPDs, particularly benzodiazepines while 12 (1.2%) used illicit drugs. Of those with drug-positive urine, 123 (69.1%) had no documented history of CPD non-medical and illicit drug use. Being an inpatient (OR=10.90, p<0.001) was independently associated with CPD non-medical use. Additionally, being an inpatient (OR=8.29, p<0.001) and tobacco consumption (OR=1.85, p=0.041) were associated with CPD non-medical and illicit drug use combined. Among participants, 119 (9.3%) reported CPD lifetime use, and this was independently associated with education level (OR=2.71, p<0.001) and history of treatment for substance abuse (OR=2.08, p=0.018).

Conclusions

CPD non-medical use is common among Uganda’s psychiatric patients, and more prevalent than illicit drug use. Rapid diagnostic assays may be needed in psychiatric care in resource limited settings. It is necessary to assess how CPD non-medical use impacts mental care outcomes and patient safety. High risk groups like inpatients and tobacco consumers should be prioritised in psychiatric screening.
Impact of chronic Achilles tendinopathy on health-related quality of life, work performance, healthcare utilisation and costs
Authors: Sleeswijk Visser Tjerk S O , van der Vlist Arco C , van Oosterom Robert F , van Veldhoven Peter , Verhaar Jan A N , de Vos Robert-Jan
Published: March 2021

Objectives

To evaluate the impact of Achilles tendinopathy (AT) on quality of life (QoL), work performance, healthcare utilisation and costs in adults with conservatively treated chronic midportion AT.

Methods

This cross-sectional survey-based study included 80 patients and took place in a sports medicine department of a large regional hospital in the Netherlands. Data were collected before any intervention was given. Primary outcome was the EuroQol questionnaire (EQ-5D). The EQ-5D expresses the percentage of moderate/major problems on the domains self-care, anxiety/depression, mobility, usual activities and pain/discomfort. Secondary outcomes were the number of previous healthcare visits, work performance during the period of symptoms and estimated annual direct medical and indirect costs per patient as a result of AT.

Results

All 80 patients completed the questionnaires. The EQ-5D scores were low for the domains self-care (1%) and anxiety/depression (20%), and high for the domains mobility (66%), usual activities (50%) and pain/discomfort (89%). Patients with AT mainly reported an impact on work productivity (38%). Work absenteeism due to AT was present in 9%. The total median (IQR) number of annual healthcare visits was 9 (3–11). The total mean (SD) estimated annual costs were €840 (1420) per patient with AT (mean (SD) US$991 (1675)).

Conclusions

This study shows the large impact of AT on QoL and work productivity. This study also provides new information about the socioeconomic impact of AT, which emphasises that this common and longstanding disease causes substantial costs. These findings stress the need for optimised treatment and improved preventive interventions for AT.

Trial registration number

NCT02996409.
Dynamic Changes in Aortic Stiffness after Substantial Weight Loss by Laparoscopic Sleeve Gastrectomy in Patients with Obesity: A 1-Year Follow-Up Study
Authors: Gul Murat , Inci Sinan , Aktas Halil , Yildirim Oguz , Alsancak Yakup , Ozkan Namik
Published: March 2021

Arterial stiffness has been identified as a powerful and independent risk factor for cardiovascular disease. Obesity is associated with an increased risk of aortic stiffness (AS) and adverse cardiovascular events. Herein, we aimed to evaluate the effects of weight loss after laparoscopic sleeve gastrectomy (LSG) on AS in individuals with morbid obesity by using the transthoracic echocardiography (TTE).

A total of 53 patients with obesity (17 males, 36 females) who underwent LSG and did not have any known heart disease were included in the study. The AS parameters were measured with TTE. The demographic and echocardiographic data of the patients were studied before, at 1 month and 12 months after surgery.

The mean age of the study group was 34.41±11.62, 68% of whom were female. There were no significant differences in terms of the standard echocardiography and Doppler measurements as compared with preoperative values (all p>0.05). When the elastic parameters of the aorta were compared, no significant differences were detected regarding aortic strain (%) ((16.28±4.11) vs (16.68±4.56), p=(0.998)), distensibility (cm2/dyn) ((6.74±1.78) vs (7.03±2.31), p=(0.997)) and Aortic Stiffness Index values ((10.73±3.84) vs (10.63±3.34), p=0.998) between baseline and first month after surgery. In the 12-month follow-up, it was determined that the aortic strain ((16.28±4.11) vs (22.74±5.79), p≤0.001) and distensibility ((6.74±1.78) vs (10.34±3.059), p<0.001)) values increased at significant levels.

Weight loss by LSG improves arterial stiffness parameters in patients with obesity over a 1-year follow-up.