bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Instabilities in Platform-Type Parallel Manipulators due to Singular Configurations
Authors: Shi X. , Fenton R. G.
Published: March 2021

In this paper, a new method for identifying singular configurations causing instabilities in a platform-type parallel manipulator is presented. The method is based on a recently developed forward instantaneous kinematic formulation and the principle of reciprocity of screws. An analytical singularity condition is derived for a Stewart Platform type manipulator by using the method. It is believed that this is the first analytical expression for configuration singularity of a platform-type parallel manipulator. An illustrative example of a 3 DOF parallel manipulator is also discussed in detail in the paper.
The Health Management of Machines, Mechanisms, and Robots Featuring Macroscopically Smart Composite Materials With Embedded Fiber Optic Sensors
Authors: Hansknecht B. P. , Thompson B. S. , Gandhi M. V. , Foiles C.
Published: March 2021

The embryonic discipline of macroscopically smart materials featuring polymeric fiberous composite laminates with embedded optical fibers provides significant technological advantages if they are incorporated in the next generation of the machines, mechanisms, and robotic systems. These technological advantages can be exploited during the manufacture, the service life, and the failure prediction phases of the part life-cycle. The embedded optical fibers permit the manufacture of the part to be optimized during autoclave processing, for example, by controlling the state of cure and temperature using a new generation of manufacturing techniques involving closed-loop control algorithms. Subsequently, the optical fibers permit the vibrational response, stresses, strains, and deflections to be continuously monitored during the service of the mechanical system, and where appropriate, embedded actuator materials can be activated to develop a more desirable response as part of a health management philosophy. Finally, the optical sensing system enables the failure of the part to be predicted, because the propagation of a crack through the structure will result in the fracturing of the embedded optical fibers, and hence, the severing of the optical light paths which can be detected by this class of photonic system. This paper introduces this potentially powerful health management philosophy to the field of mechanism design by presenting for the first time experimental results from an investigation of the dynamic response of a slider-crank mechanism with a smart graphite-epoxy laminated connecting-rod featuring a polarimetric fiber optic sensor. This investigation examines one facet of this new philosophy; namely, a health monitoring activity in which the vibrational response of a flexible machine element is monitored using a fiber optic sensor.
Characterization of Robotic Operations for Dual-Arm Robots With Cooperating Manipulators
Authors: Cox Daniel J. , Tesar Delbert
Published: March 2021

Cooperating manipulators in dual-arm robots usually result in a mechanically overconstrained system having more actuator resources than freedom of motion, or an excess of actuator inputs. This redundancy in drivability condition provides the opportunity for choice, or decision, the fundamental quality of an intelligent machine. There are in general an infinite number of selections for actuator inputs and resultant internal load states to satisfy a specified output load state and motion trajectory in a dual-arm robot with cooperating manipulators. A geometric operation descriptor provides the fundamental geometric relationships for motion and constraint in cooperative dual-arm robotic operations. Cooperative modes of operation for dual-arm robots are characterized using the geometric operation descriptor to provide a basis of solution to the redundancy in drivability of the system. Modes of operation involving single objects as well as two-object operations are described for the dual-arm robot with cooperating manipulators.
Optimization of the Robot Calibration Process
Authors: Zak G. , Fenton R. G. , Benhabib B.
Published: March 2021

Most industrial robots cannot be off-line programmed to carry out a task accurately, unless their kinematic model is suitably corrected through a calibration procedure. However, proper calibration is an expensive and time-consuming procedure due to the highly accurate measurement equipment required and due to the significant amount of data that must be collected. To improve the efficiency of robot calibration, an optimization procedure is proposed in this paper.

The objective of minimizing the cost of the calibration is combined with the objective of minimizing the residual error after calibration in one multiple-objective optimization. Prediction of the residual error for a given calibration process presents the main difficulty for implementing the optimization. It is proposed that the residual error is expressed as a polynomial function. This function is obtained as a result of fitting a response surface to either experimental or simulated sample estimates of the residual error. The optimization problem is then solved by identifying a reduced set of possible solutions, thus greatly simplifying the decision maker’s choice of an effective calibration procedure. An application example of this method is also included.
Unique Joint Displacement Generation for Redundant Robotic Systems
Authors: Chung Y. S. , Griffis M. , Duffy Joseph
Published: March 2021

This paper presents a novel, practical, and theoretically sound kinematic control strategy for redundant serial manipulators. This strategy yields repeatability in the joint space of a redundant serial manipulator whose end effector undergoes some general cyclic type motion. This is accomplish by defining a potential energy function that is based on springs being theoretically or conceptually located in the joints of the manipulator (torsional springs for revolute joints, translational springs for prismatic joints).

Previous researchers have also minimized potential energy functions to solve the inverse kinematic problem for redundant serial manipulators. However, to the authors’ knowledge, the new strategy is the first to include the free angles of torsional springs and the free lengths of translational springs. This is important because it provides a meaningful reference for zero potential energy i.e. when all joints are at their free angles or free lengths. This reference for zero potential energy ensures the repeatability in the joint space of a redundant serial manipulator whose end effector undergoes a cyclic-type motion.

Choices for the free angle and torsional stiffness of a joint (or the free length and translational stiffness) are made based upon the mechanical limits of the joint. For instance, the free angle of a joint is that angle which is midway between joint limits. Joint stiffnesses are chosen so that the most dexterous joint is the most pliable, and so that the least dexterous joint is the stiffest. This strategy ensures that joints of the manipulator are kept away from their respective joint limits.
A Generalized Performance Sensitivity Synthesis Methodology for Four-Bar Mechanisms
Authors: Lee Ming-Yih , Erdman Arthur G. , Faik Salaheddine
Published: March 2021

A generalized accuracy performance synthesis methodology for planar closed chain mechanisms is proposed. The relationship between the sensitivity to variations of link lengths and the location of the moving pivots of four-link mechanisms is investigated for the particular objective of three and four position synthesis. In the three design positions case, sensitivity maps with isosensitivity curves plotted in the design solution space allow the designer to synthesize a planar mechanism with desired sensitivity value or to optimize sensitivity from a set of acceptable design solutions. In the case of four design positions, segments of the Burmester design curves that exhibit specified sensitivity to link length tolerance are identified. A performance sensitivity criterion is used as a convenient and a useful way of discriminating between many possible solutions to a given synthesis problem.
The Anatomy of Smart Materials and Structures, and Their Influence on Design Practices for Mechanisms, Machines and Robotic Systems
Authors: Thompson B. S. , Gandhi M. V. , Choi S. B.
Published: March 2021

This paper presents an exposition on the embryonic eclectic field of smart materials and structures, prior to discussing how this class of biomimetic materials will influence design practices in the field of machines, mechanisms and robotic systems. The development of smart structures typically involves the macroscopic synthesis of materials with both functional and structural properties by exploiting biomimetic philosophies. The most innovative class of these macroscopically adaptive materials typically feature combinations of actuators, sensors, and microprocessing capabilities which enable them to actively change their mass, stiffness and energy-dissipation characteristics in real-time. Such capabilities are particularly relevant to the design of mechanisms, machines and robots that must operate under variable service conditions and in unstructured environments.
Geometric Conditions for the Satisfaction of Order in Four Position Synthesis of Four-Bar Linkages
Authors: Mirth John A.
Published: March 2021

A mechanism that cannot pass through all precision positions in the correct sequence is said to violate the order condition. This paper establishes the order requirements for the precision position synthesis of all Grashof and non-Grashof four-bar linkages. These order requirements are based on three geometric characteristics of the four-bar mechanism: the angle of one of the rotating links that is attached to the ground link; the limits that the entire mechanism imposes on this rotating link; and the dyad configurations for the dyad that is opposite the ground pivot of this link. The results improve upon traditional discussions of the order problem by including all four-bar linkages, rather than just those of a specified Grashof type. A table summarizes the results in a form that allows for their implementation into computer programs for linkage design and analysis.
A New Parameter for Transmission Quality and Output Sensitivity Analysis of Mechanisms
Authors: Wu Fubang , Lankarani H. M.
Published: March 2021

A Transmission Merit Parameter (TMP) is defined in this paper which comprehensively reflects the transmission quality and output sensitivity of a mechanism to its dimensional disturbance. The TMP is derived from direct differentiation of the independent relationships among the coordinates in the form of the determinant of the constrain Jacobian matrix. It is shown that the idea of TMP is the extension of conventional transmission angle and without a measure such as TMP, representation of the transmission quality for complex mechanisms would be a difficult task.
Rectified Synthesis of Coupler-Driven Four-Bar Mechanisms for Four-Position Motion Generation
Authors: Bawab S. , Kinzel Gary L. , Waldron Kenneth J.
Published: March 2021

A rectified synthesis procedure for designing coupler-driven four-bar mechanisms to pass a moving lamina through four precision positions is developed. The procedure includes the elimination of circuit, branch and order defects. This is achieved with the aid of Roberts’ linkage. The procedure has been implemented in the interactive synthesis package RECSYN.
Machine Design Projects Using TK Solver
Authors: Goatley Mike , Echempati Raghu
Published: March 2021

In a machine design course, working on design projects is essential to learning how to apply the material. However, the hand calculations are often long or require the use of a computer to supply more information than possible through hand calculations alone, especially for repetitious iterations. TK Solver, by Universal Technical Systems, Inc. makes these iterations quick and easy compared to other available software. TK Solver has been used to make the large number of calculations needed, in the design of machine elements for example, to select bearings from a catalog knowing the required life and load rating. Also, in the design of gears and pinions, many trials of running through the same set of equations while only changing the diametral pitch and face width are needed to completely specify the dimensions, of the component while falling within the necessary safety factor criterion. Once these equations are set up, the necessary variables can be changed to accommodate any type of bearing load or gear combination.
An Automated Inversion Apporach to Closed-Form Kinematic Analysis of Planar Mechanisms
Authors: Biswas Arunava , Kinzel Gary L.
Published: March 2021

In this paper an inversion approach is developed for the analysis of planar mechanisms using closed-form equations. The vector loop equation approach is used, and the occurrence matrices of the variables in the position equations are obtained. After the loop equations are formed, dependency checking of the unknowns is performed to determine if it is possible to solve for any two equations in two unknowns. For the cases where the closed-form solutions cannot be implemented directly, possible inversions of the mechanism are studied. If the vector loop equations for an inversion can be solved in closed-form, they are identified and solved, and the solutions are transformed back to the original linkage. The method developed in this paper eliminates the uncertainties involved, and the large number of computations required in solving the equations by iterative methods.
Circuit Rectification for Four Precision Position Synthesis of Stephenson Six-Bar Linkages
Authors: Mirth John A. , Chase Thomas R.
Published: March 2021

Circuit rectification ensures that a linkage may reach all precision positions without disassembly. The circuit characteristics of Stephenson six-bar linkages can be established by examining the interaction of the four-bar and five-bar chains within the linkage. Preliminary synthesis of the four-bar chain introduces specific conditions that must be met by the five-bar chain for all of the precision positions to lie on a single circuit. These conditions are based on the relationship between the four-bar coupler curve and the dyads/triads that are generated from the centerpoint curve of the final synthesis step. The travel of the coupler curve between the precision positions is compared with the reach of the final dyad/triad to establish circuit conditions. The circuit conditions are applied to points along the centerpoint curve of the final synthesis step to identify those curve segments which will produce a mechanism with all precision positions on the same circuit.
Kinematic and Static Force Analysis of Rocker-Pin Jointed Silent Chains With Involute Sprockets
Authors: Bucknor N. K. , Freudenstein Ferdinand
Published: March 2021

A quasi-static model has been developed for a silent (inverted-tooth) chain drive featuring a rocker-pin-jointed chain and sprockets with involute teeth. The model incorporates the effects of clearances in the rocker-pin joints and the geometry of link/sprocket engagement. The influence of various model parameters on the chain drive torque-ratio is examined, a primary point of interest being the fluctuations in the torque-ratio due to chordal action. In some cases, the torque-ratio variation is found to be less than that for the equivalent pin-jointed chain drives. Additionally, the center distances corresponding to the maximum and minimum torque variation are not fixed, as in the case of a pin-jointed chain. An optimization method is used as an aid in determining the governing geometric constraints since multiple joint configurations can be selected, given the clearances introduced by the rocker-pin joints. The resulting system of equations is fully constrained for a physically consistent chain configuration.
The Second Order Optimum Synthesis of a Compound Mechanism With Flexible Member
Authors: Meng Caifang , Dai Zuo , Cha Jianzhong
Published: March 2021

An optimum synthesis of a compound mechanism with flexible member (CMFM) is reported in this paper. First, the concepts of the first order optimum synthesis (FOOS) and the second order optimum synthesis (SOOS) are given. Then, the SOOS for the CMFM in a complete period and a half of period are carried out based on the mathematical model established for the SOOS of the CMFM. The results of the SOOS are obtained through the IIO software, an integrated intelligent optimization software environment, and the differences between specified and generated angular velocities are analyzed.
Kinematic Analysis and Synthesis Type III Movable Spatial 6R Mechanism With Three Adjacent Parallel Axes
Authors: Lee Chung-Ching , Yan Hong-Sen
Published: March 2021

Based on matrix algebra, we derive the general analytical kinematic solutions of Type II movable spatial 6R mechanism with three adjacent parallel axes. This 6R mechanism was previously identified by the authors, and one of its special form is proposed as the retracting and wheel twisting mechanism for aircraft landing gears. A graphical synthesis technique by descriptive geometry is presented for the kinematic synthesis of the landing gear mechanism. A numerical example is given, and the mobility of this design is verified by computer animation of motions.
Nonlinear Optimal Design of Dynamic Mechanical Systems
Authors: Potter T. E. , Willmert K. D. , Sathyamoorthy M.
Published: March 2021

Mechanism path generation problems which use link deformations to improve the design lead to optimization problems involving a nonlinear sum-of-squares objective function subjected to a set of linear and nonlinear constraints. Inclusion of the deformation analysis causes the objective function evaluation to be computationally expensive. An optimization method is presented which requires relatively few objective function evaluations.

The algorithm, based on the Gauss method for unconstrained problems, is developed as an extension of the Gauss constrained technique for linear constraints and revises the Gauss nonlinearly constrained method for quadratic constraints. The derivation of the algorithm, using a Lagrange multiplier approach, is based on the Kuhn-Tucker conditions so that when the iteration process terminates, these conditions are automatically satisfied. Although the technique was developed for mechanism problems, it is applicable to any optimization problem having the form of a sum of squares objective function subjected to nonlinear constraints.
Backlash Control via Redundant Drives: An Experimental Verification
Authors: Tsai Lung-Wen , Chang Sun-Lai
Published: March 2021

In this paper, a novel concept for the control of backlash in geared servo-mechanisms is demonstrated with a prototype manipulator. The concept utilizes unidirectional redundant drives to assure positive coupling of gear meshes at all times and, thereby, eliminates backlash completely. To establish a proof of concept, a two-DOF prototype manipulator with three unidirectional drives is designed and tested. Dynamic model based on Lagrange’s formulation is established. A PID controller using computed torque control technique is developed. Two experiments, one with redundant drives and the other without redundant drives, are conducted. The experimental results demonstrate that use of unidirectional redundant drives improves the repeatability of a manipulator by an order of magnitude.
Steady-State Responses of an RSRC-Type Spatial Flexible Linkages
Authors: Chang R. Y. , Sung C. K.
Published: March 2021

This paper presents an analytical and experimental investigation on the steady-state responses of an RSRC-type spatial flexible linkage. The kinematic analysis of the spatial rigid-body motion is performed using kinematic constraint equations to yield linear and angular positions, velocities and accelerations of the linkage. A mixed variational principle is, then, employed to derive the equations of motion governing the longitudinal, transversal and torsional vibrations of the flexible link and the associated boundary conditions. Based on these equations, the steady-state responses are predicted. Finally, an RSRC-type four-bar spatial flexible linkage is constructed and the experimental study is performed to examine the predictive capability proposed in this investigation. Favorable comparisons between the analytical and experimental results are obtained.
An Efficient Manipulator Dynamics Formulation Based Upon Newton-Euler Equations and the ZRP Method
Authors: Cheng Harry Hui , Gupta Krishna C.
Published: March 2021

This paper presents a formulation of robot manipulator inverse dynamics based upon the Newton-Euler equations and the zero reference position method. The angular velocities and accelerations, linear accelerations of the mass centers, and inertia forces and moments of each link of the manipulator are computed recursively starting from the base to the end-effector. But, the joint reaction forces and moments, and joint actuator forces or torques are computed recursively from the end-effector to the base. The formulation is at first carried out in the current position and then reformulated by directly utilizing the zero reference position data. The former formulation is intuitively simple; while the latter is computationally more efficient. A parametric study is also conducted to compare the relative efficiency of this formulation with the previously available formulation.
Jacobian and Stiffness Analysis of a Novel Class of Six-DOF Parallel Minimanipulators
Authors: Tahmasebi Farhad , Tsai Lung-Wen
Published: March 2021

The Jacobian and stiffness matrices of two types of novel, six-DOF parallel minimanipulators are derived. A minimanipulator consists of three inextensible limbs, each of which is driven by a two-DOF driver. Bilinear stepper motors are used as drivers in the first type minimanipulator, whereas five-bar linkages are used as drivers in the second type minimanipulator. All of the minimanipulator actuators are base-mounted. Inextensible limbs (and five-bar linkage drivers in the second type minimanipulator) improve positional resolution and stiffness of the minimanipulators in certain directions. It is shown that, at the central configuration, the stiffness matrix of the first type minimanipulator can be diagonalized (decoupled). It is also shown that the first type minimanipulator can be designed to possess direct or torsional isotropic stiffness properties. Moreover, guidelines for designing the drivers of the second type minimanipulator are established.
On the Effects of the Operating Speed on the Dynamic Behavior of Manipulators With Rigid Links
Authors: Tu Q. , Rastegar Jahangir
Published: March 2021

The effect of tile operating speed on the dynamic behavior of robot manipulators is determined by examining the potential resonant energy transfer to a robot manipulator system during its motion by the different harmonics of the actuating torques (forces). The potential resonant energy transfer (hereafter called the energy transfer), particularly by the higher harmonics present in the actuating torques, is of considerable interest since they represent one of the main sources of vibration and control problems in such systems. For a given trajectory pattern, the ratios of the total energy transfer by the non-trajectory and the “higher” harmonics of the actuating torques to the total energy input to the system are determined. Here, the higher harmonics refers to the harmonics with frequencies above the highest frequency of the trajectory harmonics. It is shown that in the absence of gravity, for the class of nonlinear dynamics systems represented by the rigid link robot manipulators, the ratios are independent of the speed of operation. For a given path geometry, the relative magnitude of the individual energy transfer is, however, dependent on the positioning of the path within the workspace of the manipulator and the pattern of motion. In the presence of gravity, as the operating speed is increased, the ratios tend to their no gravity values. The application of the developed method to manipulator synthesis and path and trajectory planning for minimal system susceptibility to vibrational excitation, and a number of related topics of interest are discussed.
Bidirectional Extreme Convergency Methods (BECM) to Identify the Mobility Regions of the RSSR Mechanism
Authors: Tian Luo Hong
Published: March 2021

The BECM are proposed to classify spatial four-link mechanisms according to groups such as crank-rocker, double-rocker and double-crank (drag link). The BECM can determine the feasible regions and number of the extreme values exactly and solve them simply without complex derivation and calcultion. The paper concerns itself mainly with the RSSR linkage but it can be applied also to other types such as RSSP, RSCP, RSCR etc. The method is very simple and the geometric concept is very clear. Although the graphical methods is mainly introduced in this paper, certainly, it can also be coded in computer to solve out their accurate values.
Active Control for the Complete Dynamic Balancing of Linkages
Authors: Angeles Jorge , Nahon Meyer A. , Thümmel Thomas
Published: March 2021

This paper deals with the dynamic balancing of linkages. For one-degree-of-freedom linkages, this task consists of eliminating both the shaking moment and the shaking force exerted by the inertia forces of the moving links on the frame. While the latter can be eliminated by properly deciding on both the location of the mass centers and the ratios of the masses and link lengths involved, the shaking moment due to these forces cannot be eliminated in this way. Indeed, the elimination of the shaking force is attained by having the two transmitted forces cancel each other, although each individual force does not necessarily vanish, thereby still producing a shaking moment. In this paper, we propose the use of redundant motors in order to eliminate the reaction forces transmitted to the base, thereby also eliminating the shaking moment due to these forces. However, the net moment acting on the frame is shown to be unaltered by this technique.
Modeling of Multibody Flexible Articulated Structures With Mutually Coupled Motions: Part II — Application and Results
Authors: Xu Jiechi , Baumgarten Joseph R.
Published: March 2021

The application of the systematic procedures in the derivation of the equations of motion proposed in Part I of this work is demonstrated and implemented in detail. The equations of motion for each subsystem are derived individually and are assembled under the concept of compatibility between the local kinematic properties of the elastic degrees of freedom of those connected elastic members. The specific structure under consideration is characterized as an open loop system with spherical unconstrained chains being capable of rotating about a Hooke’s or universal joint. The rigid body motion, due to two unknown rotations, and the elastic degrees of freedom are mutually coupled and influence each other. The traditional motion superposition approach is no longer applicable herein. Numerical examples for several cases are presented. These simulations are compared with the experimental data and good agreement is indicated.
Using Constraint Management Techniques to Design Spur and Helical Gears
Authors: Agrawal Rajiv , Sridhar Natarajan , Kinzel Gary L.
Published: March 2021

This paper presents the use of constraint management techniques to design spur and helical gears. The constraints for gear design are presented in a declarative manner such that they can be incorporated in a general Design Shell environment. A declarative representation allows the designer to experiment with a number of different designs and perform “what-if” scenarios. Since spur gears form a subset of helical gears, the mathematical formulation is presented for helical gears only. The analysis of helical gears is based on the AGMA/ANSI Standard 2001-B88.
The Creation of a Multi-Link Load Balancing Mechanism for Planetary Gearing: Part 2 — Optimum Mechanism Selection and Dimension Determination
Authors: Hong Zhang , Cao Wei-qing , Yang Ting Li , Chu Jin Kui
Published: March 2021

This paper is the second of a series of two papers which designed a new type of load balancing mechanisms for planetary gearings with arbitrary number of planets. In this paper the common expression of the non-uniform load share factor was deduced, and a function parameter:force-arm factor and their solution was given. That makes it possible that the dimensions and the ability of load equilibrium of Multi-Link Load Balancing Mechanisms can be determined. The criteria of optimum load balancing Mechanisms selection were set up with consider of the effects of turning pair clearances, and optimum mechanisms were selected among the 15 candidates obtained in Part 1. Finally, it was demonstrated that the optimum multi-link load balancing mechanisms for arbitrary number of planets had the similar topological structures and same function and performence of load equilibrium.
An Optimal Design Method for Damping Structure With Constrained Viscoelastic Material
Authors: Imai Satomitsu , Sato Taichi , Setone Syouichi , Masukawa Tetsuo
Published: March 2021

This paper describes an optimal design method for a damping structure using constrained viscoelastic material. The relationship between viscoelastic material behavior and the damping effect, is analyzed by finite element method, where viscoelastic material is modeled by discrete spring elements with the equivalent stiffness and loss factor. This finite element model is applied to the design of a head-gimbal-assembly (HGA) of a magnetic disk device and its reliability is confirmed experimentally. The analysis shows that the maximum deformation of the constrained viscoelastic material occurs at the edge area, so to optimize the damping structure, this area should be placed on the area of high strain energy. Although the damping effect by constrained viscoelastic material has been considered due to shear deformation of viscoelastic material, in this analysis, tensile deformation of the egde of viscoelastic material is strongly related to the damping effect for the bending and torsional modes of HGA. Therefore, an accurate analysis must consider tensile deformation of viscoelastic material.
Canonical Perspective Image (CPI) Algorithm
Authors: Malladi N. S. , Chirala Padmanayan , Philipose Shibu M.
Published: March 2021

A Canonical Perspective Image (CPI) Algorithm has been developed to obtain iteratively, a unique silhouette of an object corresponding to a given resting flat or face. The geometric properties of this unique silhouette can be used to determine the position and orientation of the object resting on a flat surface.
Computer Control of a Flexible Robotic Cell
Authors: Akcadag C. , Shirkhodaie A. , Soni A. H.
Published: March 2021

Intelligent robotic systems require a tremendous flexibility and intelligence to execute complex tasks. To facilitate task planning of intelligent robots and integrate sensory information for on-line task monitoring, there is a need to establish a communication linkage between robot controller and human operator through a computer. This paper presents the design of a generic cell controller for intelligent planning and execution of robotic cell operations and for real-time task monitoring. This paper details the architecture of hardware and software developed for the control of a commercial robot interfaced with a computer through a parallel I/O communication bus. Results indicate that by means of a relatively inexpensive setup, flexibility with regard to coordinated activities of robotic cells can be greatly increased.
Computerized Engineering Manuals Simplify and Expedite Engineering Tasks
Authors: Walters Jeffrey J. , Schiavello Daniel V.
Published: March 2021

Probably no task is as common in engineering as reaching for a reference manual or handbook, searching through it to find a section that applies to the task at hand, selecting a series of formulas, generating equations and then solving them with a calculator or computer. Recently, the time required to perform this everyday function has been dramatically reduced through use of a new generation of computerized engineering manuals, such as DE/CEM, which automate the tasks of finding the relevant material and performing the necessary calculations.
Information-Integration of Manufacturing Systems Using Object-Oriented Technology
Authors: Jazbutis Gintas , Wang Ching-Yang , Chadha Bipin , Fulton Robert E.
Published: March 2021

This paper describes an object-oriented approach to building an information system for optical fiber manufacturing. This object-oriented approach takes the following steps: defining the information and systems requirements, building the models of the manufacturing system, and implementing a prototype information system. This paper gives the details of the work done to date in the first two steps and compares the process with a previous effort in building a relational-based information system.
The myobiid mites (Acariformes, Eleutherengona, Myobiidae) from Mexico: hosts, distribution and identification key for the genera and species

Authors: Herrera-Mares Angel , Guzmán-Cornejo Carmen , Morales-Malacara Juan B.
Published: March 2021

The family Myobiidae Mégnin, 1878 includes permanent parasites of the fur of different orders of mammals. Because the information on this family is scarce and scattered, in this work, we compile the available information on Myobiidae in Mexico. In total, we recorded 41 species (one undetermined, one a species inquirenda) belonging to 13 genera and three subfamilies, associated with four orders of mammals: Chiroptera, Didelphimorphia, Rodentia and Soricomorpha. We also reported for the first time in Mexico Eudusbabekia jimenezi (Dusbábek, 1967) and E. saguei (Dusbábek, 1967), parasitizing bats of the family Mormoopidae in the States of Colima, Nayarit and San Luis Potosí, and Acanthophthirius lasiurus (Fain & Whitaker, 1976) associated with the bat Lasiurus cinereus (Palisot de Beauvois) (family Vespertilionidae) in Ciudad de México. We recorded new associations with bat hosts: E. provirilia Morales-Malacara, Guzmán-Cornejo & López-Ortega, 2002 with Leptonycteris yerbabuenae Martínez & Villa (Phyllostomidae); E. saguei with Pteronotus davyi Gray (Mormoopidae), and Ioannela leptonycteris (Fain, 1973) with L. yerbabuenae. In this work, Zacaltepetla hoffmannae Basurto-R., 1973 is treated as a species inquirenda for the first time. We also provide an identification key to the genera and species of Myobiidae found in Mexico.
Morphological ontogeny of Eremobelba geographica (Acari: Oribatida: Eremobelbidae), with comments on Eremobelba Berlese

Authors: Seniczak Stanisław , Ivan Otilia , Kaczmarek Sławomir , Seniczak Anna
Published: March 2021

The morphological ontogeny of Eremobelba geographica Berlese, 1908 is described and illustrated. This species was investigated mainly in ecological and biological aspects. It inhabits forest soils and cultivated areas, but is not abundant, and adults dominate in extracted samples. In the juveniles, the prodorsal seta in is short, and the bothridial seta is setiform. The nymphs are quadrideficient and eupheredermous, i.e. they carry exuvial scalps of the previous instars, using a cornicle. Paraproctal setae occur in all juvenile instars, which is rare in Brachypylina, and hypertrichy occurs in the aggenital region of the deutonymph, tritonymph and adult, and adanal region of the adult. In all instars, seta d on all genua and tibiae is present, except for tibia I of adult.
Vertical and slanted sound propagation in the near-ground atmosphere: Amplitude and phase fluctuations
Authors: Kamrath Matthew J. , Ostashev Vladimir E. , Wilson D. Keith , White Michael J. , Hart Carl R. , Finn Anthony
Published: March 2021

Sound propagation along vertical and slanted paths through the near-ground atmosphere impacts detection and localization of low-altitude sound sources, such as small unmanned aerial vehicles, from ground-based microphone arrays. This article experimentally investigates the amplitude and phase fluctuations of acoustic signals propagating along such paths. The experiment involved nine microphones on three horizontal booms mounted at different heights to a 135-m meteorological tower at the National Wind Technology Center (Boulder, CO). A ground-based loudspeaker was placed at the base of the tower for vertical propagation or 56 m from the base of the tower for slanted propagation. Phasor scatterplots qualitatively characterize the amplitude and phase fluctuations of the received signals during different meteorological regimes. The measurements are also compared to a theory describing the log-amplitude and phase variances based on the spectrum of shear and buoyancy driven turbulence near the ground. Generally, the theory correctly predicts the measured log-amplitude variances, which are affected primarily by small-scale, isotropic turbulent eddies. However, the theory overpredicts the measured phase variances, which are affected primarily by large-scale, anisotropic, buoyantly driven eddies. Ground blocking of these large eddies likely explains the overprediction.
The Role of Structured Foam Rolling Programs in Improving Hamstring Flexibility: A Critically Appraised Topic
Authors: Khan Irfan A. , Henderson Kelley
Published: March 2021

Focused Clinical Question: What is the efficacy of structured foam rolling protocols at increasing hamstring muscle flexibility in active adults when compared with just maintaining regular levels of activity? Clinical Bottom Line: There is significant evidence to support the use of structured foam rolling programs in active adults to improve hamstring flexibility.
Differences in V˙O2max Measurements Between Breath-by-Breath and Mixing-Chamber Mode in the COSMED K5
Authors: Winkert Kay , Kirsten Johannes , Kamnig Rupert , Steinacker Jürgen M. , Treff Gunnar
Published: March 2021

Purpose: Automated metabolic analyzers are frequently utilized to measure maximal oxygen consumption (). However, in portable devices, the results may be influenced by the analyzer’s technological approach, being either breath-by-breath (BBB) or dynamic micro mixing chamber mode (DMC). The portable metabolic analyzer K5 (COSMED, Rome, Italy) provides both technologies within one device, and the authors aimed to evaluate differences in between modes in endurance athletes. Methods: Sixteen trained male participants performed an incremental test to voluntary exhaustion on a cycle ergometer, while ventilation and gas exchange were measured by 2 structurally identical COSMED K5 metabolic analyzers synchronously, one operating in BBB and the other in DMC mode. Except for the flow signal, which was measured by 1 sensor and transmitted to both devices, the devices operated independently. was defined as the highest 30-second average. Results: and were significantly lower in BBB compared with DMC mode (−4.44% and −2.71%), with effect sizes being large to moderate (ES, Cohen d = 0.82 and 1.87). Small differences were obtained for respiratory frequency (0.94%, ES = 0.36), minute ventilation (0.29%, ES = 0.20), and respiratory exchange ratio (1.74%, ES = 0.57). Conclusion: was substantially lower in BBB than in DMC mode. Considering previous studies that also indicated lower values in BBB at high intensities and a superior validity of the K5 in DMC mode, the authors conclude that the DMC mode should be selected to measure in athletes.
Influence of an Elementary Methods Course and Early Field Experience on Preservice Teachers’ Value Orientations
Authors: May Leah K. , Curtner-Smith Matthew D. , Wind Stefanie A.
Published: March 2021

Purpose: To determine the influence of an elementary methods course and early field experience on eight preservice teachers’ (PTs’) value orientations. Method: The theoretical perspective employed was occupational socialization. Data were collected with the short form of the value orientation inventory and five qualitative techniques (formal and informal interviews, nonparticipant observation, critical incidents, and stimulated recall). The value orientation inventory profiles for the instructor and PTs were visually inspected for similarities and changes. Analytic induction and constant comparison were employed to analyze the qualitative data. Results: Value orientations of PTs with teaching and moderate coaching orientations were influenced by the methods course and early field experience, while those of PTs with strong coaching orientations were not. Factors leading to this evolution were the curriculum model employed, the instructor, and PTs’ increased confidence and knowledge of students. Summary and Conclusions: The study highlights the importance of faculty facilitating reflection on connections between instructional models and value orientations and how these relate to PTs’ beliefs.
Mucosal Priming with a Recombinant Influenza A Virus-Vectored Vaccine Elicits T-Cell and Antibody Responses to HIV-1 in Mice
Authors: Wang Jinlin , Shu Tao , Deng Weiqi , Zheng Yali , Liao Min , Ye Xianmiao , Han Lujie , He Ping , Zheng Xuehua , Li Ting , Feng Ying , Hu Fengyu , Li Pingchao , Sun Caijun , Chen Ling , Li Feng , Feng Liqiang
Published: March 2021

An effective HIV-1 vaccine remains elusive despite nearly 40 years of research. CD8
+
T cells and protective antibodies may both be desirable for preventing HIV-1 infection in susceptible mucosal sites.
Isotopically “heavy” pyrite in marine sediments due to high sedimentation rates and non-steady-state deposition
Authors: Liu Jiarui , Antler Gilad , Pellerin André , Izon Gareth , Dohrmann Ingrid , Findlay Alyssa J. , Røy Hans , Ono Shuhei , Turchyn Alexandra V. , Kasten Sabine , Jørgensen Bo Barker
Published: March 2021

Sedimentary pyrite formation links the global biogeochemical cycles of carbon, sulfur, and iron, which, in turn, modulate the redox state of the planet's surficial environment over geological time scales. Accordingly, the sulfur isotopic composition (δ34S) of pyrite has been widely employed as a geochemical tool to probe the evolution of ocean chemistry. Characteristics of the depositional environment and post-depositional processes, however, can modify the δ34S signal that is captured in sedimentary pyrite and ultimately preserved in the geological record. Exploring sulfur and iron diagenesis within the Bornholm Basin, Baltic Sea, we find that higher sedimentation rates limit the near-surface sulfidization of reactive iron, facilitating its burial and hence the subsurface availability of reactive iron for continued and progressively more 34S-enriched sediment-hosted pyrite formation (δ34S ≈ −5‰). Using a diagenetic model, we show that the amount of pyrite formed at the sediment-water interface has increased over the past few centuries in response to expansion of water-column hypoxia, which also impacts the sulfur isotopic signature of pyrite at depth. This contribution highlights the critical role of reactive iron in pyrite formation and questions to what degree pyrite δ34S values truly reflect past global ocean chemistry and biogeochemical processes. This work strengthens our ability to extract local paleoenvironmental information from pyrite δ34S signatures.
Re-Os geochronology highlights widespread latest Mesoproterozoic (ca. 1090–1050 Ma) cratonic basin development on northern Laurentia
Authors: Greenman J. Wilder , Rooney Alan D. , Patzke Mollie , Ielpi Alessandro , Halverson Galen P.
Published: March 2021

The terminal Mesoproterozoic was a period of widespread tectonic convergence globally, culminating in the amalgamation of the Rodinia supercontinent. However, in Laurentia, long-lived orogenesis on its eastern margin was punctuated by short-lived extension that generated the Midcontinent Rift ca. 1110–1090 Ma. Whereas this cratonic rift basin is typically considered an isolated occurrence, a series of new depositional ages demonstrate that multiple cratonic basins in northern Laurentia originated around this time. We present a Re-Os isochron date of 1087.1 ± 5.9 Ma from organic-rich shales of the Agu Bay Formation of the Fury and Hecla Basin, which is one of four closely spaced cratonic basins spanning from northeastern Canada to northwestern Greenland known as the Bylot basins. This age is identical, within uncertainty, to ages from the Midcontinent Rift and the Amundsen Basin in northwestern Canada. These ages imply that the late Mesoproterozoic extensional episode in Laurentia was widespread and likely linked to a common origin. We propose that significant thermal anomalies and mantle upwelling related to supercontinent assembly centered around the Midcontinent Rift influenced the reactivation of crustal weaknesses in Arctic Laurentia beginning ca. 1090 Ma, triggering the formation of a series of cratonic basins.
Supplemental Material: Controls on the origin and evolution of deep-ocean trench-axial channels
Authors: McArthur Adam , Tek Daniel
Published: March 2021

Information on acquisition, processing, and interpretation of seismic data, and the statistical methodology and sensitivity analysis.
Supplemental Material: Transient Permian-Triassic euxinia in the southern Panthalassa deep ocean
Authors: Grasby Stephen , al. et
Published: March 2021

Analytical data.
Incidence of diabetes in South Asian young adults compared to Pima Indians
Authors: Narayan K M Venkat , Kondal Dimple , Kobes Sayuko , Staimez Lisa R , Mohan Deepa , Gujral Unjali P , Patel Shivani A , Anjana Ranjit Mohan , Shivashankar Roopa , Ali Mohammed K , Chang Howard H , Kadir Masood , Prabhakaran Dorairaj , Daya Natalie , Selvin Elizabeth , Tandon Nikhil , Hanson Robert , Mohan Viswanathan
Published: March 2021

Introduction

South Asians (SA) and Pima Indians have high prevalence of diabetes but differ markedly in body size. We hypothesize that young SA will have higher diabetes incidence than Pima Indians at comparable body mass index (BMI) levels.

Research design and methods

We used prospective cohort data to estimate age-specific, sex, and BMI-specific diabetes incidence in SA aged 20–44 years living in India and Pakistan from the Center for Cardiometabolic Risk Reduction in South Asia Study (n=6676), and compared with Pima Indians, from Pima Indian Study (n=1852).

Results

At baseline, SA were considerably less obese than Pima Indians (BMI (kg/m2): 24.4 vs 33.8; waist circumference (cm): 82.5 vs 107.0). Age-standardized diabetes incidence (cases/1000 person-years, 95% CI) was lower in SA than in Pima Indians (men: 14.2, 12.2–16.2 vs 37.3, 31.8–42.8; women: 14.8, 13.0–16.5 vs 46.1, 41.2–51.1). Risk of incident diabetes among 20–24-year-old Pima men and women was six times (relative risk (RR), 95% CI: 6.04, 3.30 to 12.0) and seven times (RR, 95% CI: 7.64, 3.73 to 18.2) higher as compared with SA men and women, respectively. In those with BMI <25 kg/m2, however, the risk of diabetes was over five times in SA men than in Pima Indian men. Among those with BMI ≥30 kg/m2, diabetes incidence in SA men was nearly as high as in Pima men. SA and Pima Indians had similar magnitude of association between age, sex, BMI, and insulin secretion with diabetes. The effect of family history was larger in SA, whereas that of insulin resistance was larger in Pima Indians

Conclusions

In the background of relatively low insulin resistance, higher diabetes incidence in SA is driven by poor insulin secretion in SA men. The findings call for research to improve insulin secretion in early natural history of diabetes.