bluuebunny/crossref_metadata_2025 huggingface dataset:
Nuclear-Associated Plasmid, But Not Cell-Associated Plasmid, is Correlated With Transgene Expression in Cultured Mammalian Cells
Authors: James Molly B. , Giorgio Todd D.
Published: November 2021

Intracellular plasmid is rapidly incorporated into the nucleus of HeLa cells following cationic lipoplex transfection. CV1 cells are less effective in translocating plasmid to the nucleus and also express less transgene than HeLa cells. Cultured HeLa and CV1 cells and corresponding isolated nuclei were analyzed after transfection of a Cy3 labeled pGreenLantern plasmid (Cy3-pGL). Flow cytometry was used to measure both plasmid delivery and transgene expression from the plasmid encoding a CMV promoter driven green fluorescent protein. During transfection, HeLa cells rapidly incorporated the plasmid, reaching a maximum of 80% Cy3-pGL positive cells 8 hours post-transfection. The average Cy3-pGL positive HeLa cell contained approximately 2470 plasmid copies. 48% of the nuclei isolated from the transfected HeLa cells were positive for the plasmid marker after 8 hours. In contrast to HeLa cells, fewer CV1 cells and CV1 nuclei incorporated plasmid DNA with peak transfection occurring after 12 hours for 36% of the cells and after 8 hours for 12% of the nuclei. However, the average Cy3-pGL positive CV1 cell did not have a significantly different number of total cellular plasmid copies than the average positive HeLa cell. CV1 nuclei, however, had half as much plasmid as HeLa nuclei. HeLa cells are more efficient than CV1 cells at transporting plasmid from the cytoplasm to the nucleus. This study demonstrates the use of a novel quantitative method to study plasmid transport from the cytoplasm to nucleus and the effect on transgene expression.
Pressure Increases Inert Particle Uptake in Human Saphenous Vein
Authors: MacLennan M. J. , Leavitt B. J. , Schmoker J. D. , Chesler N. C.
Published: November 2021

Cardiovascular disease is one of the leading causes of death in the United States, and coronary artery bypass graft surgery (CABG) is one of the mainstays of treatment for this disease [1]. Since artificial vascular grafts suitable for coronary bypass are not yet available, autologous internal mammary artery (IMA) and saphenous vein are used to bypass diseased tissue [1]. While IMA grafts have high long-term patency rates, saphenous vein grafted into the arterial position tends to stenose and eventually thrombose.
Creep Analysis of Wafer Level Chip Scale Package (WLCSP) With 96.5Sn-3.5Ag and 100In Lead-Free Solder Joints and Microvia Build-Up Printed Circuit Board
Authors: Lau John H. , Pan Stephen H. , Chang Chris
Published: November 2021

In this study, time-temperature-dependent nonlinear analyses of lead-free solder bumped wafer level chip scale package (WLCSP) on printed circuit board (PCB) assemblies subjected to thermal cycling conditions are presented. Two different lead-free solder alloys are considered, namely, 96.5wt%Sn-3.5wt%Ag and 100wt%In. The 62wt%Sn-36wt%Pb-2wt%Ag solder alloy is also considered to establish a baseline. All of these solder alloys are assumed to obey the Garofalo-Arrhenius steady-state creep constitutive law. The shear stress and shear creep strain hysteresis loops, shear stress history, and shear creep strain history at the corner solder joint are presented for a better understanding of the thermal-mechanical behaviors of lead-free solder bumped WLCSP on PCB assemblies. Also, the effects of microvia build-up PCB on the WLCSP solder joint reliability are investigated.
Nonlinear-Time-Dependent Analysis of Micro Via-In-Pad Substrates for Solder Bumped Flip Chip Applications
Authors: Lau John H. , Lee S. W. Ricky , Pan Stephen H. , Chang Chris
Published: November 2021

An elasto-plastic-creep analysis of a low-cost micro via-in-pad (VIP) substrate for supporting a solder bumped flip chip in a chip scale package (CSP) format which is soldered onto a printed circuit board (PCB) is presented in this study. Emphasis is placed on the design, materials, and reliability of the micro VIP substrate and of the micro VIP CSP solder joints on PCB. The solder is assumed to obey Norton’s creep law. Cross-sections of samples are examined for a better understanding of the solder bump, CSP substrate redistribution, micro VIP, and solder joint. Also, the micro VIP CSP PCB assembly is subjected to thermal cycling tests.
Analysis of a Thermoelectric Cooler With Non-Uniform Heating
Authors: Ellsworth M. J. , Simons R. E.
Published: November 2021

This paper discusses a methodology for incorporating the behavior of a thermoelectric cooling module in a finite element model of an electronic chip module. A background discussion of thermoelectric cooling is provided followed by a discussion of algebraic solutions for either chip temperature or allowable power on a uniformly powered multi-chip module. The basis and method of implementing an integrated thermoelectric-conduction model in ANSYS is presented. Example calculations are presented and discussed for a thermoelectrically cooled non-uniformly powered MCM. A “quasi-superposition” approach combining results obtained by 1-D algebraic solutions with thermoelectric cooling, with ANSYS results without thermoelectric cooling is also discussed. This approach offers a means to estimate the chip temperatures on an MCM cooled by a thermoelectric module without the need to actually build a detailed and time consuming finite element model of the thermoelectric module.
Refrigeration Cooled Computers: Application and Review
Authors: Schmidt R. R. , Ellsworth M. J. , Chu R. C. , Agonafer D.
Published: November 2021

This paper outlines and discusses the application conditions pertinent to refrigeration cooling a computer processor at both the module and system level. Amongst the issues that are addressed are total refrigeration heat load (comprised of active and parasitic heat loads), coefficient of performance (COP), continuous operation (reliability, concurrent maintenance), system heat rejection, condensation formation, and temperature stability. The paper will then examine how a vapor compression refrigeration system has been incorporated in IBM’s high end (Gx) servers. Finally, the paper will touch upon some of the additional complexities of operation at very low temperatures (less than −40 °C).
A New 3D Analytical Method for Calculating the Longitudinal Stress-Strain of Bones, as ‘N’ Different Asymmetrical Linear Elastic Materials, Loaded Together Eccentrically
Authors: Arafati Nader
Published: November 2021

We describe a three-dimensional analytical method to evaluate the stress-strain of « n » different asymmetrical linear elastic materials, loaded together by eccentric forces and moments.

If one assumes that each bone is composed of a number of different linear elastic materials, this method could be used to determine the stress-strain values of any bone. Mesh generation is unnecessary with this method, the only requirement being to determine the contours of each material.

We used this method to analyze the longitudinal stresses imposed on the femur, after implantation of cemented hip prosthesis. The results were compared with those of finite element analysis without any contact elements. Considerable differences were found, particularly for exterior prosthesis contours. When the same error was entered into a cylindrical analytical model, the similar errors were found, indicating that not using contact elements may result in unacceptable errors with the finite element analysis method.
Bone Elastometric Measurements by Ultrasound Reflectometry: Observations on Physiology and Functional Organization of Bone
Authors: Mehta Shreefal S. , Antich Peter P. , Smith Billy , Lewis Matthew A. , Richer Edmond
Published: November 2021

Bone mechanical properties are strongly dependent on orientation and optimally adapted to the directional stresses induced by load bearing and muscular activity. Spatial and directional homogeneity and a slow rate of change of material mechanical properties are commonly assumed in the literature. The assumptions are based on limitations of widespread diagnostic techniques but are contradicted by results from several established techniques, including ultrasound reflectometry.

A device based on the ultrasound reflectometry technique measures the mechanical elasticity of bone noninvasively at multiple sites and orientations, making it possible to carry out longitudinal studies at any chosen location in vivo. In vivo elastometric measurements over the length of a tibia were obtained with this device, demonstrating quantitatively for the first time the spatial and directional heterogeneity of bone material properties in vivo. Clinical observations made on two subjects also suggest that bone does exhibit rapid changes in response to altered activity levels.
Command Shaping for MIMO Nonlinear Systems Using Iterative Learning Control With Application to an RTP System
Authors: de Roover Dick , Emami-Naeini Abbas , Ebert Jon L. , Kosut Robert L.
Published: November 2021

Input command shaping for temperature control of fast-ramp RTP systems is investigated from an open-loop-input point of view, i.e., for a given desired temperature recipe a set of lamp command profiles is determined such that the resulting set of measured temperatures approaches the desired recipe as closely as possible. Because of the inherent nonlinear behavior of RTP systems, a command shaping method has been developed that iteratively modifies the optimal linear commands to compensate for the nonlinearities. This method, which has been derived from Iterative Learning Control (ILC), shapes the input commands iteratively so as to minimize the two-norm between a desired output trajectory and the simulated current output trajectory. The technique is applicable to MIMO systems and can handle constraints on the input commands. Application of this method to a fast-ramp oxidation (RTO) and fast-ramp spike anneal (RTA) process for a model of a generic RTP system demonstrates its usefulness for nonlinear systems.
Axis Motion Based System Calibration of an Automated Disassembly Work Cell
Authors: Bailey-Van Kuren Michael M.
Published: November 2021

This paper presents an approach to calibrate a robotic cell consisting of a robot, a positioning table and a stereo vision system in an autonomous manner. The approach is designed to simplify the error relationships and parameter updates and thus eliminating the need for a large nonlinear search. The accumulation of error in the kinematic model is avoided by calibrating one joint at a time from the manipulator hand to the manipulator base. The error in the manipulator and sensor models are identified by using least squares estimates.

The manipulator kinematic model is parameterized by the joint axes position and orientation instead of the Denavit-Hartenberg parameters. This approach leads to a more “user-friendly” interface to the calibration results. The model is derived using screw geometry, resulting in a simple relationship between the joint axis parameters and the path produced by moving a particular joint. The robot model provides an example of a chain of revolute joints while the positioning table provides an example of prismatic joints. Model simplifications result from each of these simplified motions. As with other methods, this formulation produces a four by four homogeneous transformation matrix which defines the motion of any point on the hand of the manipulator in terms of the sensed joint angles.

It is shown that each camera can independently estimate the manipulators’ paths using the image data and distances along the path from the manipulator model. Error in position and orientation between the resulting two path estimates identify the relative error between the camera models. It is shown that a solution exists for any set of three or more points generated from one axis.
Adaptive Contact Force Control of a Flexible Beam Using Output Feedback
Authors: Yim Woosoon
Published: November 2021

This paper presents an adaptive force trajectory control of a flexible beam using a piezoceramic actuator. Based on the adaptive backstepping method, a force control system using only force measurement is designed. For the derivation of the control law, it is assumed that parameters of the beam and contact surface stiffness are unknown. It is shown that in the closed-loop system, the contact force tracks a given reference trajectory and the beam vibration is suppressed as well. Digital simulations results show that the closed-loop system has good transient behavior and robust performance in the presence of uncertainties in the parameters of the flexible beam and the contact surface.
Performance Improvement of Proportional Directional Control Valves: Methods and Experiments
Authors: Bu Fanping , Yao Bin
Published: November 2021

This paper studies local valve control of the electro-hydraulic system. The sluggish response of hydraulic control valve usually becomes the bottleneck of whole system performance. Although fast valves (e.g. high-bandwidth servo-valves) are available, they are far more expensive than slow valves (e.g. proportional directional control valves). To improve the performance of proportional directional control valves, three different types of controllers are synthesized. Firstly, based on the pole zero cancellation technique, an open loop compensator is designed which requires the accurate valve dynamic model information; Secondly, a full state feedback adaptive robust controller (ARC) is synthesized, which effectively takes into account the effect of parametric uncertainties and uncertain nonlinearities such as friction force and flow force. Finally, an output feedback ARC controller is synthesized to address the problem of unmeasurable states. Theoretically, the proposed ARC controllers guarantee a prescribed output tracking transient performance and final tracking accuracy while achieving asymptotic output tracking in the presence of parametric uncertainties. Comparative experimental results are obtained to show the advantages and limitations of each method.
Mathematical Modeling of a Two Spool Flow Control Servovalve Using a Pressure Control Pilot
Authors: Anderson Randy T. , Li Perry Y.
Published: November 2021

A nonlinear dynamic model for an unconventional, commercially available electrohydraulic flow control servovalve is presented. The valve is a two-stage valve and differs from the conventional servovalve in that it does not require a feedback wire and ball, and the boost stage uses two spools, instead of a single spool, to meter flow into and out of the valve separately. Consequently, the valve is significantly less expensive. The proposed model captures the nonlinear and dynamic effects not present in previous models. The model has been coded in Simulink and experimentally validated.
Recent Developments in Research on Intelligent Machines
Authors: Garg Devendra P.
Published: November 2021

Recently there has been in evidence a lot of interest in intelligent machines all over the world [1–2]. Such machines have the capability to sense both expected and unexpected changes in their work environment and take appropriate actions quickly and efficiently. International Business Machines (IBM) Corporation’s Deep Blue computer [3], that played the game of chess against Mr. Kasparov, is an example of an intelligent machine in action against a human. The basic challenge in the area of intelligent machines is to integrate computers, sensors, controllers, actuators, software, and machines that would lead to devices that are adaptive, flexible, and robust. In this paper, in addition to presenting the basic concepts related to intelligent machines, several areas of their application are discussed. This is followed by a description of intelligent systems and of the resources invested in research by the U.S. National Science Foundation during the past several years. Examples of a few projects supported under the Learning and Intelligent Systems (LIS) program and the Knowledge and Distributed Intelligence (KDI) initiative are given. The paper concludes with a discussion of research challenges in the area of intelligent machines.
An Energy-Enhanced Design of Experiments Method Applied to Multi-Body Models
Authors: Christensen Bjorn G. , Ferris John B. , Stein Jeffrey L.
Published: November 2021

Computer models of complex mechanical systems are being used more frequently and effectively due to ever increasing computing power. These models have improved the design process by allowing designers to create virtual prototypes of systems. Computer models permit iterative designs, thereby allowing the designer to run hundreds of simulations in the time it would take to make one physical model and test it. This ease of iteration has made design of experiments (DOE) analyses easy to carry out on the computer models. A DOE analysis provides excellent information regarding the specific output function being examined but may overlook some of the global effects that these changes may have on the system. A new design tool is developed in this work that addresses this deficiency. The new method greatly improves upon existing design tools such as DOE. Specifically, the new method augments a traditional DOE study with an Activity study, which focuses on the energy flow in the system and provides a larger picture of the system dynamics. Instead of using only a DOE to determine which elements’ properties should be changed, the Activity of the elements is also considered. This helps prevent altering a parameter or set of parameters to achieve a desired response at the expense of other unforeseen results. This idea is demonstrated by using an ADAMS model of a small production vehicle to design for improved ride. The example shows that design changes based on a DOE analysis alone can improve the ride quality, but also can alter other system responses significantly. When an Activity analysis is combined with the DOE study, the ride quality is improved, but the effects on other aspects of the system are greatly reduced. Augmentation of DOE with Activity allows a specific design goal to be achieved and also provides global information about the system. This allows the engineer to make informed decisions about the effects of changes on the system.
Model Based Diagnostics for Vehicle Systems
Authors: Pisu Pierluigi , Rizzoni Giorgio , Soliman Ahmed , Amberkar Sanket , Murray Brian , Jalics Laci
Published: November 2021

In recent years, increasing interest and requirement for improved vehicle performance, reliability and safety has focused attention on the use of Fault Detection & Isolation when designing vehicle control systems. In order to achieve this FDI schemes, particular vehicle subsystems integrated with a controller have been proposed.

This paper introduces a new Model-Based Fault Detection and Fault Diagnosis method for monitoring the overall vehicle system performance.
Modified Skyhook Control for the Semi-Active Macpherson Strut Suspension: A New Model and HILS
Authors: Hong Keum-Shik , Sohn Hyun-Chul , Hedrick J. Karl
Published: November 2021

In this paper, a modified skyhook control for the semi-active Macpherson suspension system is investigated. A new model for the Macpherson type suspension, which incorporates the rotational motion of the unsprung mass, is introduced and a feedback control law utilizing the modified skyhook control strategy is derived. Also, two filters to estimate the absolute velocity of the sprung mass and the relative velocity of the rattle space are designed. For testing the control performance, the actual damping force has been included in the hardware-in-the-loop simulations. The control performances of the semi-active system and a passive one have been compared. HILS results are provided.
Incorporation of Neuro-Fuzzy Knowledge for Fast Measurement of Combustion Engine Maps
Authors: Hafner Michael , Müller Norbert , Semmler Sascha , Škrjanc Igor
Published: November 2021

Map-measurements of internal combustion (IC) engines concerning torque, emissions and other effects are essential for the design and application of an engine control system. With the rising number of engine input- and output variables, however, the measuring efforts rise exponentially and can require up to several weeks. State-of-the-art approaches usually measure equidistant grids in multidimensional input space (load, speed, injection angle, exhaust gas recirculation (EGR), blade position of variable turbine geometry turbochargers (VTG), etc). This paper proposes an extraction of relevant measuring points by a neuro-fuzzy pre-analysis of data of comparable engine types. The chosen data is then sorted according to its temperature behavior in order to reduce time due to waiting for stable temperatures. During the actual measurement, new temperature levels are reached faster by use of a temperature controller and the measuring time can further be reduced by means of output models.
Robust and Efficient Feedrate Selection for 3-Axis Machining
Authors: Hemmett Jeffrey G. , Fussell Barry K. , Jerard Robert B.
Published: November 2021

This research effort is focused on improving the efficiency of CNC machining by automatic computer selection of feedrate for 3-axis sculptured surface machining. A feedrate process planner for complex sculptured end milling cuts is described and the geometric model of ball end milling is developed in detail. For each tool move, the geometric model calculates the cut geometry, and a mechanistic model is used along with a maximum allowable cutting force to determine a desired feedrate. The results are written into the part program resulting in a file with optimized feedrates. Experimental tests on a sculptured surface demonstrate the robustness and efficiency of the algorithms in maintaining a desired force.
Object-Oriented Modeling for Real-Time Simulation
Authors: Otaduy Miguel A. , Martínez Ana I. , Vidarte Ana , Landaluze Joseba , Reyero Raúl
Published: November 2021

The fast growing processing capability of digital circuits allows real-time simulation of mechatronic systems to embrace new applications at a lower cost. However, the development of real-time simulation models is still a difficult task. Object-oriented modeling, along with efficient mathematical formulation, seems to solve this matter. The work covered by this paper was carried out in order to evaluate existing possibilities for the development of real-time simulations of mechatronic systems by means of object-oriented modeling tools.
Structured Modeling of Mechatronic Components Using Multiport Templates
Authors: Hales Michael K. , Rosenberg Ronald C.
Published: November 2021

Mathematical modeling of mechatronic systems is increasing in its importance to industry for product development. Mathematical modeling helps companies reduce the lead time for new product development, allows for consideration of more design alternatives, provides a means for capture of engineering knowledge, and facilitates sharing of engineering efforts with suppliers. Structured modeling further assists engineers in meeting these goals by supporting effective, clear communication of model information. This paper describes a modeling environment for mechatronic system design based on structured modeling concepts. Structured modeling is implemented using a multiport template approach. A multiport template allows the engineer to create new user-defined model types, which are in turn used to create computational instances. The focus is on mechatronic component modeling. Illustrations of the method are given.
Modeling, Realization, and Simulation of Thermo-Fluid Coupled Systems Using Singularly Perturbed Sliding Manifolds
Authors: Gordon Brandon W. , Asada Harry
Published: November 2021

A new approach based on sliding control is presented for modeling and simulation of thermo-fluid systems described by differential-algebraic equations (DAEs). The dynamics of thermo-fluid systems are often complicated by momentum interactions that occur on a time scale that is orders of magnitude faster than the time scale of interest. To address this problem the momentum equation is often modeled using algebraic steady state approximations. This will, in general, result in a model described by nonlinear DAEs for which few control methods are currently applicable. In this paper, the modeling problem is addressed using an approach that systematically constructs an explicit state space approximation of the DAEs. The state space model can in turn be used with existing control methods. This procedure, known as realization, is achieved by solving an associated nonlinear control problem by combining boundary layer sliding control with the singular perturbation method. The necessary criteria for key properties such as convergence are established. Further, the new approach is illustrated using a vapor compression cycle example. This demonstrates significant advantages over directly modeling momentum interactions.
Flexural Joints in Mechanisms
Authors: Koster M. P.
Published: November 2021

The application of flexural joints in mechanisms has a number of advantages. Extreme repeatability of position is obtained because of the absence of backlash and friction. From a tribological point of view, no lubrication is needed and no wear exists. In many cases their application gives rise to a low cost assembly. Flexural elements have their particular drawbacks as well. Deflections are limited; only oscillating motions can be performed and work has to be done as a consequence of the elastic deflection. Flexural fatigue sets another limit to their application.

The paper gives an overview of a design methodology that has been developed at the Philips Center for Industrial Technology by the author and his colleagues over the last several decades. Some aspects of this methodology are well known; other aspects are unique. The methodology is described in detail in a book by the author about design principles (Koster 1998). The methodology has been used to design hundreds of practical mechanisms incorporated in scientific instruments, manufacturing equipment and consumer goods. Many examples are given in (Koster 1998). Several interesting examples are given in this paper.
Spatial Compliances Achieved With Serial Elastic Mechanisms
Authors: Huang Shuguang , Schimmels Joseph M.
Published: November 2021

Previously, the structure of a spatial stiffness matrix and its realization using a parallel elastic system have been addressed. This paper extends those results to the analysis and realization of a spatial compliance matrix using a serial mechanism.

We show that, a spatial compliance matrix can be decomposed into a set of rank-1 primitive matrices, each of which can be realized with an elastic joint in a serial mechanism. To realize a general spatial compliance, the serial mechanism must contain joints that couple the translational and rotational motion along/about an axis. The structure of a spatial compliance matrix can be uniquely interpreted by a 6-joint serial elastic mechanism whose geometry is obtained from the eigenscrew decomposition of the compliance matrix. The results obtained from the analysis of spatial compliant behavior and its realization in a serial mechanism are compared with those obtained for spatial stiffness behavior and its realization in a parallel mechanism.
Human-Robot Interactive Control Sharing Same Workspace
Authors: Lew Jae Y. , Jou Yung-Tsan , Pasic Hajrudin
Published: November 2021

The paper presents a basic motion planning / feedback control algorithm for a robot working with a human in the same workspace. With the proposed control scheme, robots can be safe and easy to use when unexpected events occur. The algorithm is based on: (1) inertia reduction (2) passivity and (3) parametric path planning. A preliminary simulation study is performed to show its effectiveness with a two link manipulator.
Virtual Surfaces and Haptic Shape Perception
Authors: Robles-De-La-Torre Gabriel , Hayward Vincent
Published: November 2021

Lateral force fields (LFFs) have been used before to generate haptic textures [3]. We propose that LFFs can be used to study haptic shape perception. We present preliminary results of an experiment in which human subjects interact with realistic LFFs. The LFFs encode shape information in the magnitude of unidimensional force vectors. Subjects explore the LFFs and classify them into haptic categories. We found that subjects can consistently perform this classification. This and subjects’ qualitative judgments of the stimuli suggest that haptic interaction with LFFs resembles the experience of touching a real 3D object.
Improving Reality-Based Models for Vibration Feedback
Authors: Okamura Allison M. , Hage Matthew W. , Cutkosky Mark R. , Dennerlein Jack Tigh
Published: November 2021

Reality-based modeling of vibrations can be used to enhance the haptic display of hard surfaces in virtual environments. In this work, we propose modifying reality-based vibrations through psychophysical experiments. Virtual vibration models were developed from empirical vibration waveforms measured by tapping on real surfaces with the instrumented stylus of a three degree-of-freedom haptic display. The haptic display was then evaluated on its ability to display the desired waveforms. Psychophysical experiments utilizing the display were performed to evaluate the realism of various vibration parameter values used in the vibration model. From these experiments, it was discovered that the best parameters differed from those of the original reality-based model. Additional experiments verified the effectiveness of vibration feedback by showing that subjects could differentiate between materials in a virtual environment.
Toward Deformation Modeling With Haptic Feedback
Authors: Cai ZhuLiang , Dill John , Payandeh Shahram
Published: November 2021

A fast deformation modeling method is presented. Based on elastic theory, an algorithm for animating viscoelastic systems is proposed. The integration scheme derived from implicit integration allows developers to obtain interactive realistic animation of models of viscoelastic objects. This method provides a simple, stable and tunable model for deformable object suitable for virtual reality environments. An implementation demonstrates this deformation analysis approach.
Telepresent Microassembly for Industrial Applications
Authors: Anton O. , Cuiper R. , Ehrenstrasser M. , Patron C. , Reinhart G.
Published: November 2021

Today’s teleaction systems, most of which consist of single proprietary solutions, stand out for their high integration density and complexity. They are therefore only conditionally fit for industrial applications owing to the considerable amount of interfacing work required. The subject of this paper is a modular telepresence and teleaction architecture based on CORBA developed for industrial microassembly. Modularization supports the use of different commercial components on both the operator and teleoperator side. An initial test set-up consisting of a PHANTOM 6 DOF and stereoscopic projection onto a holobench is described to allow an assessment of the concept presented.
Passive Feedforward Approach to Bilateral Teleoperated Manipulators
Authors: Li Perry Y. , Lee Dongjun
Published: November 2021

A control scheme for linear dynamically similar bilateral teleoperated manipulator system which ensures that the closed loop system is energetically passive is proposed. Energetic passivity implies that the teleoperated manipulator system is safe to interact with, and that the coupling between the system and any strictly passive environment is stable. The control objective is for the two manipulators in the system to behave in unison under the influence of both the operator and the work environment, while maintaining energetic passivity. The dynamics of the system in unison and its response to the operator and work environment can be specified as kinematic and power scalings. To maintain energetic passivity with feedback and feedforward actions, the proposed control makes use of two fictitious internal energy storages. The result is that when the internal state of the storage elements are suitably initialized, the teleoperated manipulator system achieves asymptotic locking even in the presence of external (bounded) forcing from the operator and work environment.
Physically-Based Simulation of Object Manipulation
Authors: Hirota Koichi , Hirayama Masaki , Tanaka Atsuko , Hirose Michitaka , Kaneko Toyohisa
Published: November 2021

Objects manipulation is one of the most fundamental operation in the virtual environment. We propose a method to realize the manipulation via physically-based simulation. In the method, the interaction force between the user’s finger and the object is computed, and, based on the force, the motion of the object is simulated. For the fast computation of the interaction force, we propose a novel algorithm to physically simulate the interaction. This algorithm is based on the concept that the force is caused as a result of the physical constraints on the spatial motion of fingers. Through an experimental implementation, we conclude that the proposed simulation method is applicable for the real-time manipulation of objects with force feedback.
A Contact Point Intermediate Representation for 6-DOF Haptic Interaction With Dynamic Simulations
Authors: Berkelman Peter J. , Hollis Ralph L.
Published: November 2021

A new method for integrating a haptic interface device with 3-D dynamic simulations has been implemented which minimizes effects caused by the limited update rate of the simulation and unpredictable communication delays. The new contact point intermediate representation method is compared with a previously implemented method of virtual coupling. Both methods were applied to a recently developed 6 DOF haptic interface device based on Lorentz magnetic levitation connected with a real-time dynamic physical simulation environment.

With virtual coupling, the position and orientation data from the interface device and the simulated tool each act as impedance control setpoints for the other, with error and velocity feedback acting as virtual coupling between the two systems. The simple feedback coupling enables the overall stiffness and stability of the system to be tuned easily. In the contact point intermediate representation integration method, the haptic device controller uses additional contact point position and direction information from the simulation to react to user motions by changing the device impedance appropriately at the faster update rate of the controller rather than at the slower simulation rate. The contact point intermediate representation provides a crisper, more responsive feeling than virtual coupling during interaction but is not as easily stabilized. Experimental data from the virtual coupling and a modified contact point intermediate representation implementation are presented.
Haptic Rendering of Data on Irregular Grids
Authors: Novoselov Roman Y. , Lawrence Dale A. , Pao Lucy Y.
Published: November 2021

Haptic rendering of data on irregular grids requires additional data storage and real time computation compared to the same size data sets on regular grids. At the same time, it is important to keep computation time small to avoid noticeable artifacts in haptic rendering. When the rendering algorithm is implemented on DSP processors, memory is often much smaller than on contemporary general purpose computers. By appropriate partitioning of algorithms between preprocessing and real time computation, and by quantizing and packing data, we show how scientific visualization of data sets on the order of 1 million elements by real time haptic rendering can be accomplished.
HFSM-Based Software Implementation of Haptic Interactions
Authors: Chau I. , Salcudean S. E. , Pai D. K.
Published: November 2021

We present a novel method to encapsulate and formalize haptic interaction in a compact systematic format using hierarchical finite state machines (HFSMs). HFSMs capture both reality-based and synthesized haptic interactions. The lowest level states in the hierarchy are impedances implemented by the haptic device. Transitions between states are governed by inequalities defining geometric and dynamic constraints. This model is compatible with other haptic rendering techniques and can be used as a low level application programming interface. We will describe the format and implementation and illustrate the approach with an example. Experimental results with a three-degree-of-freedom planar haptic interface are also presented.
Design of a Tension Based Haptic Interface: Spidar-G
Authors: Kim Seahak , Ishii Masahiro , Koike Yasuharu , Sato Makoto
Published: November 2021

In this paper, we explain a haptic device which can input translation and orientation measuring the length of strings and display reflect force with 6 degrees of freedom (DOF) by using the tension of strings. We propose 2 methods to calculate translation and orientation and to display reflect force. Finally, we refer the characteristic of this device and its validity through the Pick-and-Place task.
GraspIt!: A Versatile Simulator for Grasp Analysis
Authors: Miller Andrew T. , Allen Peter K.
Published: November 2021

We have created a unique tool for grasp simulation, visualization, and analysis that allows a user to create and analyze grasps of a given 3D object model with a given articulated hand model. The grasps can be performed either automatically, where the system closes the fingers around the object at preset velocities, or manually through direct manipulation of the joints. As collisions occur between the links of the fingers and the object, the system locates the contacts and analyzes the evolving grasp on the fly. Each time the grasp changes, the system updates two numeric measures of quality and recomputes 3D projections of the grasp wrench space which are useful when visualizing a grasp’s capabilities. We provide examples of the system being used with four different articulated robotic hand models, each grasping different object models. We feel the system is very useful for hand designers who prototype different hand models in simulation and determine how design decisions affect a hand’s grasping ability. It is also useful for researchers in grasp planning or for simulation and virtual reality designers wishing to perform realistic grasping in a virtual setting.
Sensitivity to Visual-Haptic Asynchrony
Authors: Vogels Ingrid M. L. C.
Published: November 2021

Many application areas that involve visual displays can benefit from the addition of haptic feedback about the state of the man-machine system that is being controlled. Due to technical and physical constraints interface signals are often delayed with respect to each other and/or with respect to the action of the user. As a result an interface consisting of a visual display and a haptic interaction device does not naturally stimulate the two modalities concurrently. Asynchronies between modalities can impede the completion time of manipulation tasks and decrease subjective telepresence. Knowledge about temporal sensitivities of the human perceptual system is therefore essential in the design of man-machine interfaces. Some temporal characteristics of the visual, auditory and tactile senses have been studied in the past (e.g. Hirsh and Sherrick, 1961). However, the perception of synchrony between visual and haptic stimuli has received little attention.
Design Specifications for the Second Generation Sarcos Treadport Locomotion Interface
Authors: Hollerbach John M. , Xu Yangming , Christensen Robert R. , Jacobsen Stephen C.
Published: November 2021

The Sarcos Treadport is a locomotion interface comprised of a large tilting treadmill, an active mechanical tether, and a CAVE-like visual display. This paper presents the design specifications for the second-generation Sarcos Treadport.
Tactile Display Device Using Distributed Lateral Skin Stretch
Authors: Hayward Vincent , Cruz-Hernández Juan Manuel
Published: November 2021

In the past, tactile displays were of one of two kinds: they were either shape displays, or relied on distributed vibrotactile stimulation. A tactile display device is described in this paper which is distinguished by the fact that it relies exclusively on lateral skin stretch stimulation. It is constructed from an array of 64 closely packed piezoelectric actuators connected to a membrane. The deformations of this membrane cause an array of 112 skin contactors to create programmable lateral stress fields in the skin of the finger pad. Some preliminary observations are reported with respect to the sensations that this kind of display can produce.
Axisymmetric Stress Analysis and Strength Evaluation of Bonded Shrink Fitted Joints of Circular Pipes Subjected to Internal Pressure and Tensile Loads
Authors: Katsuo Masahide , Sawa Toshiyuki , Yoneno Masahiro
Published: November 2021

This study deals with the stress analysis and the strength evaluation of a bonded shrink fitted joint of circular pipes subjected to an internal pressure and a tensile load. In the analysis, two pipes and the adhesive are replaced with finite hollow cylinders, and the stress distributions in the joint are analyzed by using the axisymmetric theory of elasticity. From the numerical calculations, the following results are obtained: (1) Both the compressive and shear stresses at the interface between the adherend and the adhesive increase as Young’s modulus of the adherend increases. (2) The stress becomes singular at the edges of the interfaces. (3) The joint strength can be evaluated using the compressive and shear stresses near the edge of the interface. In the experiments, bonded shrink fitted joints consisting of dissimilar circular pipes were manufactured, and rupture tests of the joints were carried out by applying an internal pressure, and a tensile load to the joints. From the results, the joint strength of the bonded shrink fitted joint was found to be greater than that of the shrink fitted joint. Furthermore, the numerical results are in fairly good agreement with the experimental ones.
A New Finite Element Modeling Technique for Disbonded Adhesive Joints
Authors: Yen H.-Y. , Shen M.-H. Herman
Published: November 2021

A new disbonded interface model and a finite element procedure have been developed to calculate the stress distributions of the adhesive joints with imperfectly-bonded interfaces under tensile loading. The finite element modeling of the weakened strength of the disbonded interfaces is accomplished by a new line element and a spring element. The finite element procedure consists of a new modeling technique for assessing the effects of disbonded interfaces on the stress fields of adhesive joints. The results for this work can be used as a basis for the development of the bonded joint reliability prediction method and accept/reject inspection criteria.
Solution of Structural Mechanics Problems by the Differential Quadrature Finite Difference Method
Authors: Chen Chang-New
Published: November 2021

The differential quadrature finite difference method (DQFDM) has been proposed by the author. The finite difference operators are derived by the differential quadrature (DQ). They can be obtained by using the weighting coefficients for DQ discretizations. The derivation is straight and easy. By using different orders or the same order but different grid DQ discretizations for the same derivative or partial derivative, various finite difference operators for the same differential or partial differential operator can be obtained. Finite difference operators for unequally spaced and irregular grids can also be generated through the use of generic differential quadrature (GDQ). The derivation of higher order finite difference operators is also easy. By adopting the same order of approximation to all mathematical terms existing in the problem to be solved, excellent convergence can be obtained due to the consistent approximation. The DQFDM is effective for solving structural mechanics problems. The numerical simulations for solving anisotropic nonuniform plate problems and two-dimensional plane elasticity problems are carried out. Numerical results are presented. They demonstrate the DQFDM.
Improving an All-Aluminum Car Crashworthiness Using Numerical Simulations: The Ferrari F360 Modena Experience
Authors: Carcioffi Carlo , Gobetto Enrico , Puppini Roberto , Smeriglio Paolo
Published: November 2021

The new Ferrari F360 Modena features an innovative, all-aluminum made, body structure: sand-casting posts are connected by extruded components to realize an effective space-frame, which improves by 40% both the torsional and the bending stiffness of its steel predecessor.

Also the F360 crashworthiness took benefits by the use of aluminum extruded components: this material, indeed, features an energy absorption per mass unit capability double than steel, allowing lower deformation spaces without increasing sections.

By the way, the crashworthiness of an all-aluminum body can be affected by the presence of heat affected zone due to MIG continuous welding: the loss of mechanical characteristics of the parent metal is function of various parameters.

The present work, conducted with the expertise of Fiat Research Center - Vehicle Department, would describe how the structural behavior of an aluminum body can be simulated in numerical crash tests, based on finite element models.

The present methodology has been applied to simulate frontal and side crash according to current European Safety Standards (EC 96/79 and EC96/27), plus rear crash according to FMVSS301: the comparison with following experimental tests showed a good correlation with the deformation patterns predicted by simulation.
Crash Optimization of an Aluminum Foam-Filled Front Side Rail
Authors: Kim Heung-Soo , Wierzbicki Tomasz , Tho C. H. , Yang R. J.
Published: November 2021

This research uses aluminum foam and numerical optimization method to improve vehicle energy absorption. The front part of the rail where axial compression is dominant and three parts where global bending collapse is dominant, were reinforced by filling empty sections with aluminum foam. The existing sheet metal reinforcing elements were removed. The nonlinear explicit finite element code PAM-CRASH was used to carry out the crash simulations. Two single-objective optimization problems were performed for the aluminum foam-filled front side rail of a passenger car under impact condition to maximize the specific energy absorption, i.e., to maximize the internal energy and minimize the component weight simultaneously. The crash optimization problems were solved by using a sequential quadratic programming method, where the required functions are approximated by using design of experiments (DOE) and response surface method (RSM). In addition, the trigger on the front part of the rail was redesigned so that the peak wall force response was reduced dramatically while maintaining the required resistance in low speed crash. The results show that about 40% increase in energy absorbed and 30% increase in specific energy absorption were obtained. This research demonstrates a new way of achieving large increase in the energy absorption while maintaining high weight efficiency in crashworthiness analysis using lightweight metallic core such as aluminum foam or honeycomb.
Effect of Cerebral Vasculatures on the Mechanical Response of Brain Tissue: A Preliminary Study
Authors: Omori Kiyoshi , Zhang Liying , Yang King H. , King Albert I.
Published: November 2021

Traumatic brain injury (TBI) constitutes a significant portion of all injuries occurring as a result of automotive, motorcycle and sports related injuries. Over the years, a large amount of literature has been devoted to an increased understanding of clinical symptoms, pathological evidence and injury biomechanics for such injuries. However, the precise causal mechanism, which accounts for complex mechanical interactions and responses in an anatomical structure as complex as the brain, is not fully understood.