bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Control of a Gasoline Direct Injection Engine
Authors: Kolmanovsky I. , van Nieuwstadt M. , Sun J. , Gilbert E.
Published: December 2021

This paper addresses a problem of optimizing the operation of a gasoline direct injection (GDI) engine equipped with a Three Way Catalyst (TWC) and a Lean NOx Trap (LNT). This engine can be operated significantly lean of stoichiometry. Lean operation results in reduced pumping losses and improved fuel economy. During lean operation the LNT is used to trap the oxides of nitrogen (NOx) that constitute a regulated pollutant. As the LNT loading with NOx increases, its trapping efficiency decreases. The trap can be purged of the stored NOx by operating the engine at slightly rich of stoichiometry conditions. A trade-off has to be found between fuel economy, which deteriorates with longer purge time, and NOx reduction. It is shown how this problem can be cast in the setting of optimal control and solved numerically.
A New Approach for Canceling Turning Motion in the Locomotion Interface, ATLAS
Authors: Noma Haruo , Miyasato Tsutomu
Published: December 2021

We are concerned with communication media, especially media for daily communication. Let’s consider the case when people want to chat. For example, when we travel alone in a foreign country or when we see an impressive painting alone, we may want to enjoy the feeling with our family. We have introduced “Tel-E-Merge” as new communication system for “I wish you were here” [1]. We coined the term Tel-E-Merge to have a double meaning, Tele-Merge and Tel-Emerge, which will make it possible to merge a remotely located person, the tele-visitor, into a tele-inviter’s space through VR systems.
Smooth and Time-Optimal Trajectory Planning for Industrial Manipulators Along Specified Paths
Authors: Constantinescu D. , Croft E. A.
Published: December 2021

This paper presents a method for determining smooth and time-optimal path-constrained trajectories for robotic manipulators. The desired smoothness of the trajectory is imposed through limits on the actuator jerks. The third derivative of the path parameter with respect to time, the pseudo-jerk, is the controlled input. The limits on the actuator torques translate into state-dependent limits on the pseudo-acceleration. The time-optimal control objective is cast as an optimization problem by using cubic splines to parameterize the state space trajectory. The optimization problem is solved using the flexible tolerance method.
Sensor Fusion for Noninvasive Continuous Monitoring of Pulsating Blood Pressure Based on an Arterial Hemodynamic Model
Authors: Yang Boo-Ho , Zhang Yi , Asada Haruhiko H.
Published: December 2021

This paper presents a new approach to noninvasive, continuous monitoring of arterial blood pressure for advanced cardiovascular diagnoses. Most of the current noninvasive, continuous blood pressure measurement devices are mechanically intrusive and, therefore, cannot be used for long-term ambulatory monitoring. This new approach requires only simple, noninvasive monitoring devices such as finger photo plethysmographs and an electrical impedance plethysmograph (EIP) to monitor the dynamic behavior of the arterial blood flow. In this approach, measured signals from these noninvasive sensors on an arterial segment are integrated to estimate the blood pressure based on a hemodynamic model using a Kalman filter. It is shown that the internal variables such as the arterial blood pressure of the arterial segment can be estimated based on the measurements even though the observability condition of the system may not be met. Simulation results indicate that the approach can generate an accurate estimation of the arterial blood pressure in real-time even from noisy sensor signals.
Multiple Fault Diagnosis as Applied to Automated Vehicle Control
Authors: Howell Adam S. , Hedrick J. Karl
Published: December 2021

This paper addresses the problem of detecting multiple faults for the longitudinal control system of an automated vehicle. An existing fault diagnostic system which can isolate all single faults is extended to the diagnosis of multiple faults via improved residual processing in the form of fuzzy logic. The new diagnostic system is shown to correctly detect and isolate all single and multiple faults in a subset of the automated vehicle control system components.
The Interdisciplinary Center for Advanced Propulsion at Michigan Technological University
Authors: Abata Duane L.
Published: December 2021

This paper describes the newly formed Interdisciplinary Center for Advanced Propulsion (referred to as ICAP) at Michigan Technological University. ICAP is a United States Department of Energy Center of Excellence funded under the GATE program. The underlying goal of Center is to provide multi-disciplinary engineering training for graduate students in the area of internal combustion engines, specifically in direct injection compression ignition engines. This facility will work closely with other Department of Energy Centers of Excellence in an effort to improve the education of future scientists and engineers who will, in turn, help ensure U.S. competitiveness in the automotive industry of the future as well as reduce our growing dependency on imported petroleum.
Symmetric Dichotomy Based Inverse Dynamics of a High-Speed Flexible Beam
Authors: Wang Guoli , Li Youfu , Xu Weiliang
Published: December 2021

The symmetric acausal/causal dichotomy based model is developed for the internal dynamics of a high-speed flexible beam, and the resultant modeling redundancy is revealed. The efficient scheme of computing the bounded input-state trajectories is proposed to relieve the redundant computational burden of the time-domain inverse dynamic solutions, and its implication to trajectory planning is also investigated.
A Three Revolute Cobot Using CVTs in Parallel
Authors: Moore Carl A. , Peshkin Michael A. , Colgate J. Edward
Published: December 2021

Cobots are capable of producing virtual surfaces of high quality, using mechanical transmission elements as their basic element in place of conventional motors. Most cobots built to date have used steerable wheels as their transmission elements. We describe how continuously variable transmissions (CVTs) can be used in this capacity for a cobot with revolute joints.

The design of an “arm-like” cobot with a three-dimensional workspace is described. This cobot can implement virtual surfaces and other effects in a spherical workspace approximately 1.5 meters in diameter. Novel elements of this cobot include the use of a power wheel that couples three CVTs that are connected in parallel.
Process Monitoring and Control System to Avoid Thermal Damage in Grinding
Authors: Tönshoff H. K. , Mandrysch T.
Published: December 2021

The international competition demands a continuous improvement of the process in quality and productivity and at the same time a reduction of costs of the product. An important step to reach this target is to increase the degree of automation. Changing into highly automated and simple-operated production processes, requires a secure process-controlling. With a reproducible use of measuring devices the certainty of a high workpiece quality lasts.

For realising this reliable process controlling, a qualified system for process monitoring which uses adapted sensors and control strategies is necessary. To acquire automatically all the quality parameters relevant for ground parts as exact and fast as possible and non-destructive as well, a so-called flexible measurement cell was developed.

All parameters measured by the flexible measurement cell are used to build up a control system for the grinding process of rotational symmetrical workpieces. For the first time the possibility to control a grinding process by using the subsurface characteristic as a command variable is offered. This system is independent of the grinding wheel specification. Tests have proven the efficiency by the application of CBN as well as corundum.

The demand for a quality control and documentation beside the development of tough processes will be very important to process monitoring. For this reason a prototype system acting with an automatic control has been developed.
Transient Response of Laminated Plates Subject to Close Proximity Explosions
Authors: Coggin John M. , Chock Jeffrey M. K. , Kapania Rakesh K. , Johnson Eric R.
Published: December 2021

We study the transient response of simply supported composite plates subject to close proximity explosions. Many studies are currently availiable in which the blast load is applied uniformly across the plate; and is described by step, N-pulse, or Friedlander equations. The novel aspect considered here is the case for which the blast pressure is due to a close proximity explosion, and is therefore taken to be both spatially and temporally varying. Two methods for calculating blast pressures are developed for arbitrary blast size and distance. A FORTAN program is described that automates the application of an arbitrary blast load to a generic finite element mesh. Modal superposition and NASTRAN solution procedures are verified for several load types and stacking sequences. Results are obtained within the framework of classical and first order plate theories for a variety of parameters including; stacking sequence, blast size, blast distance, and blast calculation method.
Non-Circular Cylindrical Shells of Mid-Plane Asymmetric Construction Subjected to an Internal Pressure
Authors: Chen Zhaohui , Vinson Jack R.
Published: December 2021

In future large cargo transport aircraft, such as the Global Range Transport proposed in the New World Vistas program of the United States Air Force, it is likely that the fuselage cross-section will be non-circular. For efficient cargo space, the fuselage cross-section being investigated is that of a rectangle with rounded corners. In order to minimize the resulting bending stresses, sandwich construction is being investigated, and in particular a mid-plane asymmetric construction is being studied to utilize bending-stretching coupling to minimize these bending stresses still further in the sandwich construction. The bending-stretching coupling can be introduced by using sandwich faces of different thickness and/or different materials and/or different fiber orientation of the composite material.

The Theorem of Minimum Potential Energy is employed to investigate the subject problem. In this study, the lateral deflection that is assumed, a separable solution, employs the results of previous investigations: for the axial function, the lateral deflection of the analytical solution for a circular cylindrical shell with various boundary conditions subjected to an internal pressure is used; for the circumferential component of the lateral displacement, the series solution used previously by the authors for a ring solution of the same circumferential shape and loading is used.

The magnitude and location of the maximum stresses in each face for each material system is then determined, and the maximum deflection is also found. Thus, the mechanics of the elastic behavior of this elastic thin walled shell subjected to this loading is adequately described. Some example problems are discussed, and various material systems and geometries are compared.
Level of Detail and Multi-Resolution Modeling Techniques for Virtual Design and Prototyping
Authors: Pan Zhigeng , Zhou Kun , Cheng Chiyi , Zhang Mingmin
Published: December 2021

Reconciling scene realism with interactivity has emerged as one of the most important areas in making virtual reality feasible for large-scale CAD data sets consisting of several millions of primitives. Level of detail (LoD) and multi-resolution modeling techniques in virtual reality can be used to speedup the process of virtual design and virtual prototyping. In this paper we present an automatic LoD generation and rendering algorithm which is suitable for CAD models and propose a new multi-resolution representation scheme called MRM (multi-resolution model), which can support efficient extraction of fixed resolution and variable resolution for multiple objects in the same scene. MRM scheme supports unified selective simplifications and selective refinements over the mesh. Furthermore, LoD and multi-resolution models may be used to support real-time geometric transmission in collaborative virtual design and prototyping.
Modeling of Contact/Impact Problems in Gear Systems Dynamics
Authors: Demkowicz Leszek , Bajer Andrzej
Published: December 2021

A discretization scheme for contact/impact problems related to the modeling of gears is proposed. The problem is first discretized in time and then a variational formulation for the resulted one step problem is developed. A Finite Element discretization completes the discretization process. The scheme is reinterpretation of the general Simo-Laursen-Chavla algorithm in the contest of rigid body motion superimposed with small elastic deformation; it conserves precisely linear momentum and total energy, and approximately the angular momentum.

The discretization method is illustrated with two numerical examples: the standard 1D impact problem for an elastic rod, and a 2D model problem of an elastic wheel bouncing within a constraining box.
Experimental Study of the Acoustic Cavity Resonance in Automobile Tire Dynamic Response
Authors: Subler Molly J. , Keltie Richard F. , Tsihlas Dimitri
Published: December 2021

A series of tests were conducted to measure the dynamic stiffness transfer functions between the wheel center of a rim-mounted tire and the contact patch. Of particular interest was the interaction between the tire acoustic cavity mode and the modes of the tire/rim system. By varying the concentration of helium gas within the tire, it was possible to sweep the acoustic resonance through a group of rim/tire resonances. These results showed that there is relatively weak interaction between the cavity modes and the tire/rim modes. It was found that the resonance frequency of the cavity shifts downward with increasing tire load, and that only the z-direction dynamic stiffness is affected by load. Changes in inflation pressure were found to have no effect on the cavity resonance frequency, and increases in inflation pressure led to significant changes only in the x-direction dynamic stiffness. A simple analytical model of a coupled structural/acoustic system was found to produce results similar to those observed in the tire testing.
Parabolic Representations of Scattering Green’s Functions
Authors: Barbone Paul E.
Published: December 2021

We derive a one-way wave equation representation of the “free space” Green’s function for an inhomogeneous medium. Our representation results from an asymptotic expansion in inverse powers of the wavenumber. Our representation takes account of losses due to scattering in all directions, even though only one-way operators are used.
Reduced Models for Computational Structural Acoustics in the Medium-Frequency Range
Authors: Soize Christian
Published: December 2021

This paper deals with a method in computational structural acoustics adapted for constructing reduced models in the medium-frequency range to a general three-dimensional dissipative structure consisting of an anisotropic, inhomogeneous, viscoelastic bounded medium coupled with an internal acoustic cavity. The reduced models are obtained using the Ritz-Galerkin method for which the projection subspace corresponds to the dominant eigensubspace of the energy operator of the structure in the medium-frequency band of analysis. A basic example is presented to validate the method, for which the structure and the internal acoustic cavity have a medium-frequency behavior in the frequency band of analysis.
Finite Element Formulation of Exact Dirichlet-to-Neumann Radiation Conditions on Elliptic and Spheroidal Boundaries
Authors: Thompson Lonny L. , Huan Runnong , Ianculescu Cristian
Published: December 2021

Exact Dirichlet-to-Neumann (DtN) radiation boundary conditions are derived in elliptic and spheroidal coordinates and formulated in a finite element method for the Helmholtz equation in unbounded domains. The DtN map matches the first N wave harmonics exactly at the artificial boundary. The use of elliptic and spheroidal boundaries enables the efficient solution of scattering from elongated objects in two- and three-dimensions respectively. Modified DtN conditions based on first and second order local boundary operators are also derived in elliptic and spheroidal coordinates, in a form suitable for finite element implementation. The modified DtN conditions are more accurate than the DtN boundary condition, yet require no extra memory and little extra cost. Direct implementation involves non-local spatial integrals leading to a dense, fully populated submatrix. A matrix-free interpretation of the non-local DtN map for elliptic and spheroidal boundaries, suitable for iterative solution of the resulting complex-symmetric system is described. For both the DtN and modified DtN conditions, we describe efficient and effective SSOR preconditioners with Eisenstat’s trick based on the matrix partition associated with the interior mesh and local boundary operator. Numerical examples of scattering from elliptic and spheroidal boundaries are computed to demonstrate the efficiency and accuracy of the boundary treatments for elongated structures.
Nonlinear Deformation of Multilayer MEMS Structures
Authors: Dunn Martin L. , Zhang Yanhang , Roy Jeffrey M. , Labossiere Paul E. W. , Bright Victor M.
Published: December 2021

We studied the deformation behavior of polysilicon/gold plate structures used for microelectromechanical systems (MEMS). We designed and had fabricated (using the MUMPS foundry process at Cronos Integrated Microsystems, Inc.) a series of test structures each consisting of a square polysilicon plate partially covered with gold films of different sizes and shapes. Deformed shapes of the polysilicon/gold plates were measured at room temperature using an interferometric microscope. For relatively small gold pads, the deformations were consistent with intuition and with predictions from a linear analysis; they deformed symmetrically, with roughly spherical curvature. With increasing gold pad size, though, the plates displayed nonsymmetrical deformations with roughly cylindrical curvature. A linear analysis was insufficient to explain this result, but a nonlinear one did, indicating a bifurcation due to the development of large deformations. We discuss this interesting, and potentially useful, physical phenomena and compare measured and predicted results.
Tension Test With Single-Crystalline-Silicon Microspecimen
Authors: Yi Taechung , Kim Chang-Jin “CJ”
Published: December 2021

Young’s moduli of single crystalline silicon in three major directions are measured by direct uniaxial tension tests using a microscale beam specimen. The 10 μm thick, 50 to 100 μm wide and 6 mm long tension specimens are micromachined along the three major crystal directions from two different types of silicon-on-insulator (SOI) wafers, (100) top layer and (110) top layer. A uniaxial tension loading frame is custom-built for the testing. Stress and strain are measured using a commercial load cell and a laser interferometry system, respectively. Measured Young’s moduli in 〈100〉, 〈110〉, and 〈111〉 directions are 115.3, 169.2, and 191.1 GPa, respectively. Expected to be insensitive to the sample size or fabrication method, Young’s moduli of single crystalline silicon can be a good measure of the reliability of microspecimen tension test systems.
Residual Stress and Thickness Control of Piezoelectric Multilayer Micromirror Actuators for Initial Deflection Minimization
Authors: Kim Myeong-Jin , Cho Young-Ho
Published: December 2021

We present the design, fabrication and characterization of multi-layer piezoelectric micromirror actuators for minimizing the initial deflection without loosing the actuation performance. We modified the initial designs in order to minimize the initial deflection of the multi-layer device by changing the residual stress and thickness ratio of selected layers, thereby reducing the residual stress gradient across the multi-layered thin film materials. The modified designs are fabricated by surface-micromachining process. Experimental results indicate that over 70% reduction of the initial deflection has been achieved by the residual stress and thickness control of the multi-layer piezoelectric micromirror devices.
Meso-Scale Electromagnetic Actuators Fabricated in Low-Temperature Co-Fired Ceramic Tapes
Authors: Kim Moon , Kim Dennis , Ananthasuresh G. K. , Bau Haim H.
Published: December 2021

Meso-scale electromagnetic actuators in low-temperature co-fired ceramic (LTCC) tapes were fabricated, tested, and analyzed. Two types of designs were considered: a NdFeB permanent magnet bonded to Kapton (polyimide film material from Du Pont) beam and a permalloy (soft magnetic material) beam. In both cases, electromagnetic coils printed on ceramic tapes were used for actuation. The beam deflection was measured as a function of applied current. In the case of the permanent magnet actuator, the experimental observations were compared with theoretical predictions.
Linear Thermomechanical Microactuators
Authors: Cragun Rebecca , Howell Larry L.
Published: December 2021

Thermomechanical in-plane microactuators (TIMs) have been designed, modeled, fabricated, and tested. TIMs offer an alternative to arrays of smaller thermal actuators to obtain high output forces. The design is easily modified to obtain the desired output force or deflection for specific applications. The operational principle is based on the symmetrical thermal expansion of variable cross sections of the surface micromachined microdevice. Sixteen configurations of TIMs were fabricated of polysilicon. Finite element analysis models were used to predict the deflection and output force for the actuators. Experimental results were also recorded for all sixteen configurations, including deflections and output forces up to 20 micron and 35 dyne.
Integrated LTCC Coils for Multiple Applications in Meso-Electro-Mechanical Systems
Authors: Gongora-Rubio Mario , Santiago-Aviles Jorge J. , Sola-Laguna Luis , Smith Michael
Published: December 2021

Often the designer of small electro-mechanical systems is willing to sacrifice small size and power consumption for the sake of low cost, ease of processing and enhanced yield.

We have been working on the utilization of Low Temperature Co-fired Ceramic tapes (LTCC) for the implementation of intermediate scale (meso-scale) devices with the simultaneously or secondary task of micro-electronic packaging.

We have designed and implemented several sensors and actuators having in common the utilization of electro-magnetic forces and interactions as the fundamental working mechanism.

For this purpose we have designed and constructed a series of coils utilizing LTCC tapes suitable for multiple sensing and actuating tasks.

As sensors, we have implemented a proximity sensor and a non-contact displacement sensor and a differential pressure sensor with a ferrofluidic core.

As actuators we have implemented a normally closed valve and a Joule effect heater.
Integrated Mixing/Reaction Micro Flow Cell for Chemical and Biochemical Applications
Authors: Nakamura Ryosuke , Shoji Shuichi , Yotsumoto Akira
Published: December 2021

An integrated mixing/reaction micro flow cell which consists of a sample/reagent mixing channel, a visible port and a reaction chamber was designed, fabricated and tested. A micro cone hole array of macro porous Si was employed for reagent injection part. A visible light transparent PDMS slab was used as the visible port. A Ti-Pt thin film heater and a p-n junction diode temperature sensor were integrated on the reaction chamber to realize feedback temperature control. Uniform mixing and precise temperature control were realized by the fabricated micro flow cell. The striate and simple microchannel structure of the micro flow cell is suitable for multiplexed micro reactor for chemical and biochemical applications.
A Novel Fabrication Methodology for Micromachined Sensor-Arrays With Multi-Thickness Configuration
Authors: Li Xinxin , Lin Rongming , Bao Minhang
Published: December 2021

A novel fabrication technology is presented for bulk micro-machining of mechanical sensor-arrays, which are constructed on the scheme of different structure unit with different structural thickness for different mechanical sensitivity. Using the novel fabrication methodology, different sensing-elements of different thickness can be integrated formed. The fabrication is based on a masked-maskless two-stage anisotropic etching technology. By designing for the pattern of a layer of mask and controlling for the etching depth, several micromachined sensor-array structures have been successfully formed, such as diaphragm-array for pressure sensing-array and beam-mass array for acceleration switch, etc. The description is focused on etching principles for the multi-thickness structures, mask design and experimental results. The novel technique is quite suitable for mechanical sensor-arrays or switch-arrays structures, as lots of sensing elements with various mechanical sensitivities can be integrated fabricated by using the easy controlled etching technology. Besides, the scheme of varying thickness saves the in-plane area occupation of each structure-unit and, thus, contributes to high integration density of the array structure.
Capillary Forces at the Interface of a MEMS Actuator
Authors: Sager Chad , Saif Taher
Published: December 2021

A MEMS actuator has been designed, fabricated, and tested for the purpose of understanding capillary forces of liquids at the microscale. Experiments showed that this novel design method allows a MEMS plate, with dimensions of 100 μm × 20 μm × 4 μm thick, to be lowered by 10× its thickness into de-ionized water without inundation of the plate or the MEMS actuator’s sensitive areas. The maximum force applied to the MEMS actuator during the lowering of the device was 5.2 μN, as recorded by the calibrated MEMS springs. In another experiment, the plate was extracted from the water’s surface and a maximum force of 12.3 μN was applied to the plate. Movement of the plate during extraction was 40–50 μm. The novel design method utilizes the ability of sharp edges to prohibit the spreading of the de-ionized water. The mechanism by which the contact line between the water, air, and MEMS plate moves is described in detail. This mechanism also explains why the maximum force during the lowering of the plate was less than that of the plate being extracted from the water’s surface.
PIV Measurement of Electro-Osmotic and Pressure-Driven Flow Components in Microfluidic Systems
Authors: Cummings Eric B.
Published: December 2021

Methodology and analysis software have been developed that produce high-spatial-resolution field measurements of depthwise uniform, linear shear, and parabolic components of the velocity from particle-image videos in which the depthwise direction is not resolved. These velocity components can be approximately identified with uniform electrokinetic flow, electrokinetic flow with a ζ-potential difference between the bottom and top surfaces, and pressure-driven flow, respectively. This software has extracted measurements of the uniform and parabolic components of mixed pressure-driven and electrokinetic particle flows over heterogeneous boundaries. This decomposition of flow components simplifies the interpretation of complicated microflows.
Theory and Modeling of Continuous Electrowetting Microactuation
Authors: Lee Junghoon , Kim Chang-Jin “CJ”
Published: December 2021

This paper investigates theoretical aspects of microactuation by continuous electrowetting (CEW), actuation based on electrical control of surface tension. Known as a powerful actuation mechanism in microscale for some time, compatibility of CEW with lithographic fabrication technologies of MEMS has been demonstrated recently. This paper describes theoretical interpretation and modeling of the motion by CEW, explaining the experimental observation. We considered several electrochemical and fluid mechanical effects important for further microfluidic applications. These include details of fluid motion, modeling for different modes of motion, and the effect of fluid resistance in the micro channel.
Fuel Injection by a Thermal Microinjector
Authors: Lee Yi-Kuen , Yi Ui-Chong , Tseng Fan-Gang , Kim Chang-Jin “CJ” , Ho Chih-Ming
Published: December 2021

This paper reports a new application of a thermal microinjector for fuel injection. The paper estimates the ejected velocity of the diesel fuel droplet, and the minimum temperature for bubble formation. The fuel spray penetration is calculated by solving nonlinear equations of motion. Analysis of the temperature profile evolution and activation curve between water and diesel fuel is helpful for optimization of the microinjector design. The microinjector is fabricated using combined surface and bulk micromaching. The preliminary testing of the microinjector with fuel demonstrates the possibility of droplet ejection. Also, discussion about design issues reveals some advantages of the microinjector over the conventional fuel injector.
Surface Micromachine Microfluidics: Design, Fabrication, Packaging, and Characterization
Authors: Galambos Paul , Eaton William P. , Shul Randy , Willison Christi Gober , Sniegowski Jeffry J. , Miller Samuel L. , Gutierrez Daniel
Published: December 2021

The field of microfluidics is undergoing rapid growth in terms of new device and system development. Among the many methods of fabricating microfluidic devices and systems, surface micromachining is relatively underrepresented due to; difficulties in the introduction of fluids into the very small channels produced, packaging problems, and difficulties in device and system characterization. The potential advantages of using surface micromachining include: compatibility with the existing integrated circuit tool set, integration of electronic sensing and actuation with microfluidics, and fluid volume minimization. In order to explore these potential advantages we have developed first generation surface micromachined microfluidic devices (channels) using an adapted pressure sensor fabrication process to produce silicon nitride channels, and the SUMMiT process to produce polysilicon channels. The channels were characterized by leak testing and flow rate vs. pressure measurements. The fabrication processes used and results of these tests are reported in this paper.
Pressure Sensors in Automotive Applications and Future Challenges
Authors: Chiou J. Albert
Published: December 2021

Silicon pressure sensors have been widely used in the automotive and health care industries since the last decade, especially in automotive applications. Initially, the sensors mounted in cars are used to reduce the emission pollution and improve the gas consumption. Today, sensors are commonly used in many automotive systems. High volume, low price, and small size are the major keys to the success of the automotive pressure sensor business. More mature micromachining operations, better understanding of material properties, improved mechanical packaging, better circuit and system design, higher volume production test, and application engineering to fit the end user system requirements are all important factors that contribute to the commercial success of pressure sensors.
A Technique for Determining the Mechanical Behavior and Electrical Performance of Thin Films
Authors: Li Li , Huang Biao , Qiao Q. , Gordon M. H. , Schmidt W. F. , Ang S. S.
Published: December 2021

We describe a technique to determine the mechanical behavior and electrical performance of thin films. Thin films (2 μm) are deflected with a probe, and the displacement of the thin films and total electrical resistance are recorded. Nonlinear finite element models (ANSYS) are used to predict the corresponding force and stress. Three microstructures are built and tested: cantilever (80 μm long and 100 μm wide), bridge (290 μm long and 50 μm wide), and cross (320 μm long and 30 μm wide). No failures are observed at 15 μm deflection for all three structures, and a yield strength at least 1.34 GPa (4–20 times larger than the reported bulk value, but consistent with thin film theory) is inferred. The measured total resistance for every device ranges from open to 0.2 Ω. A direct correlation between the measured resistance and numerically predicted force (or contact pressure since the same probe tip is used in all tests) is noted, validating the numerical predictions. The bridge and cross designs appear feasible as a burn-in test socket, and we predict a mating force of 80–350 N for a 25 mm square chip with 10,000 solder balls on 250 μm spacing. This force will depend on the acceptable range of resistances as measured by our system.
Design of a Vehicle Control System for Cloning of Human Driving Behavior
Authors: Schaefer Frank R. , Schuller Juergen
Published: December 2021

This paper discusses the development of a driver model designed to mimic human behavior for any kind of driving situation. A new concept is introduced to model human short term control. It is based on a strict separation of geometric dynamic planning and plan to action mapping. Such a division enables one to model the effects motivation and knowledge independently. Moreover, it facilitates the task of debugging since errors resulting from faulty geometric dynamic planning can be isolated from those that result from lack of knowledge about the system being controlled. This article is thought to give an overview of a driver system that is novel in its structure. This approach establishes vehicle control in a way that is different from traditional linear systems.

A method is introduced that allows one to model multiple aspects of motivation and combine them in a sound manner for the task of creating a geometric dynamic plan. Motivations are divided into two classes: target motivations and limit motivations. These kinds of motivation are represented by a method to construct target and limit maps. A discussion about how to combine these maps and find the optimum geometric dynamic plan concludes the discussion about geometric dynamic planning.

Plan-to-action mapping designates the process used to find the appropriate physical values by which the driver controls the vehicle, i.e. the front wheel angle velocity and the longitudinal tracking force. This is the point where knowledge about the system must be included.

Simulation results show how to distinguish between errors arising from geometric dynamic planning and errors arising from plan-to-action mapping. Finally, results demonstrate the ability of the driver to maintain control over the vehicle system even at the limit of adhesion.
A Topology for Vehicle Stability and Handling Enhancement via Wheelslip Control
Authors: Kimbrough Scott
Published: December 2021

Wheelslip is a measure of the longitudinal slipage between the tire and the ground. Tire forces are a function of wheelslip, and by controlling wheelslip, tire forces can be modified, which in turn, allows the vehicle trajectory to be modified. A general approach is described for determining appropriate wheelslip commands, commands that will produce beneficial effects on the vehicle stability and handling.
Development of a Media Equivalent as a Foundation for a Biomimicking Vascular Prosthetic
Authors: Pawlowski Kristin J. , Bowlin Gary L.
Published: December 2021

Development of an ideal vascular replacement has been addressed with increasing urgency in recent years. To date, appropriate replacements for only large diameter bypass have been realized, employing the use of Dacron and expanded polytetrafluoroethylene. A solution for small diameter vessel bypass, however, has not yet been found. This is due mainly to acute thrombotic occlusion and chronic anastomotic hyperplasia that is introduced into these grafts due to the low blood flow velocities experienced by smaller caliber vessels and compliance mismatch between prosthetic and native vessel, respectively [1].
Fluid and Solid Mechanics in Stented Arteries
Authors: Moore James E. , Berry Joel L. , Manoach Emil , Rachev Alexander
Published: December 2021

Vascular stents are being used in increasing numbers to correct arterial flow limiting disorders. Although data exist on the in vivo performance of these devices, comparatively little is known about how these devices affect the arterial mechanical environment. The long-term success of stenting is very likely affected by the blood flow patterns and artery wall stresses that follow stent placement.

This study was undertaken to identify the mechanical environment in stented arteries and to propose a stent design that minimizes the “mechanical trauma” of stent implantation. A series of pulsatile flow visualization experiments were performed with a Johnson & Johnson Palmaz/Schatz stent inserted in a straight compliant tube. A flow loop was constructed that was capable of applying a physiologic pulsatile flow indicative of conditions in the femoral or coronary arteries. The results showed that this stent design creates complex flow patterns including large-scale vortices, and that these patterns are caused by the compliance mismatch between the stented vessel and adjacent unstented vessel.

The compliance mismatch also would be expected to create abnormal stress concentrations in the artery wall near the ends of the stent. A simplified model of an artery was constructed to estimate the stress in the artery wall. The stent/artery structure was assumed to be an axisymmetric thin shell made of a linear elastic, orthotropic material that undergoes small deformations. The stent diameter was assumed to be equal to the artery systolic diameter. The stresses were estimated under diastolic pressure, when the deflection of the artery due to the presence of the stent is greatest. It was found that the circumferential and axial stresses at the ends of the stent were 2 to 3 times higher than the stress far from the stent.

Based on these mechanical studies, a new stent design was proposed that provides a smooth transition in compliance at the proximal and distal ends of the tube. Flow visualization studies with this new stent indicate that the flow disturbances are greatly reduced with this new design. The transition zone was incorporated into the shell model to estimate the artery wall stresses induced by this new model. It was found that the stress concentration was reduced by as much as 36% from the rigid stent value. These studies demonstrate the potential complexity of flow in stented arteries and provide some recommendations for optimizing stent design from a biomechanical point of view.

This work was supported in part by a Linkage Grant from NATO.
Age-Dependent Morphological Changes of the Human Carotid Bifurcation
Authors: Lieber Baruch B. , Wakhloo Ajay K. , Luft Andreas R. , Divani Afshin A.
Published: December 2021

The development, significance and function of the human carotid sinus is not yet well understood. The arterial wall within the carotid sinus is well enervated and it contains baroreceptive neural terminals. One hypothesis that was put forward is that the dilation, which may involve all vessels of the carotid bifurcation, exists to support pressure sensing1. Another hypothesis that is supported only by phenomenological observations assume that the function of the sinus is to protect the brain by slowing blood flow and reducing pulsatility2. Yet another hypothesis interprets the sinus as an ontogenetic or phylogenic residual3. More recently, carotid hemodynamics has been investigated using in vitro and computational models. Flow patterns in the carotid sinus were found to be complex and as such have been implicated in the hetrogenesis and subsequent development of atherosclerosis at this site. However, the development of this unique sinus morphology, the role of hemodynamics in such development, and the physiological implications created by this unique morphology have not been investigated. Understanding the hemodynamic and developmental forces that play a role in remodeling of the carotid bifurcation and development of the sinus is of both fundamental and clinical interest and can lead to better prognostication and therapy of carotid disease.

Therefore, we initiated a study of the morphological development of the human carotid bulb using different age groups under the hypothesis that sinus morphology reflects an adaptive change in response to alterations in cerebral blood supply during the developmental years of the brain. This adaptation attempts to reduce hydraulic losses in the carotid bifurcation through reduced flow disturbances and maintain high level of blood supply to the brain than consumes about 15% of cardiac output under basal conditions. In addition, it may protect the sinus wall from high shear stress and/or the brain from highly pulsatile blood flow conditions.

Initially, we analyzed the angle and sinus morphology of the carotid bifurcation in pediatric and adult patients using biplane digital subtraction angiograms to characterize changes that occur as the brain matures.
Measurement by PIV of Synoptic Strain Rate Downstream of a St. Jude Prosthetic Valve
Authors: Lourenco L. M. , Spellings K. J.
Published: December 2021

It is widely accepted that shear stresses in flowing blood affect the behavior of blood cells. Effects may range from the alteration of the surface properties of platelets to damage of cell walls. These effects result in the release of biochemical signals leading to platelet aggregation and thrombus formation. While numerous studies support these observations it is still unclear what the main shear mechanisms are. However, there is large support to the notion that turbulent shear stresses (Reynolds stresses) are the major contributor to the shear experienced by blood solids.
Time-Varying Effect of Ascorbate on the Compressive Modulus and Gag Content of Chondrocyte-Seeded Agarose Cultures
Authors: Mauck Robert L. , Soltz Michael A. , Gilbert Beth , Ateshian Gerard A. , Hung Clark T. , Raia Frank J. , Valhmu Wilmot B.
Published: December 2021

The generation of a cartilage substitute will require both the mechanical and biochemical properties of the substance to approach that of native tissue. Recent studies (Buschmann et al., 1992, 1995; Bader and Lee, 1997) have shown that agarose can provide a suitable environment for the production of a mechanically functional matrix. Over time cells seeded in this matrix alter the intrinsic mechanical properties of the matrix. Additionally, several studies have included such biochemical factors as vitamin C (ascorbate) to the culture medium. This biological effector has varied effects on chondrocyte matrix biosynthesis. Specifically, it has been shown to promote calcification in chick growth plate chondrocytes (Wu et al., 1989), while it increased both type II and type I procollagen mRNA in 5 day culture (Sandell and Daniel, 1988). Conversely, it has been shown in bovine culture that aggrecan mRNA levels rise steadily in monolayer culture without ascorbate. but rise quickly and then fall off in its presence (Hering et al., 1994). To assess the effect of ascorbate in our system, primary bovine articular chondrocytes seeded in agarose, we initiated a study to examine the effects of ascorbate on both the production of cartilage extracellular matrix and the development of mechanical properties over a 14 day culture period. Three groups were studied: agarose disks without cells (control) and cell-seeded agarose disks maintained in DMEM supplemented daily with and without 50 μg/ml of ascorbate. Glycosaminoglycan (GAG) and hydroxyproline contents of each disk were determined using standard colorimetric assays.
Fluid-Induced Shear Stress Stimulates Ca2+ Signaling in Human Tendon Epitenon Cells
Authors: Francke Eric , Elfervig Michelle K. , Sood Ajay , Brown Thomas D. , Bynum Donald K. , Banes Albert J.
Published: December 2021

Tendon cells reside in an environment rich in mechanical stimuli and respond to these stimuli with a variety of activities. Whole tendon, ex vivo, responds to cyclic stretch by increasing DNA and collagen synthesis (Banes et al., 1999). Cultured epitenon and internal cells from tendon respond synergistically to cyclic tensile strain and a growth factor (Banes et al., 1995). Tendon cells stimulated by plasma membrane indentation with a micropipet propagate intercellular calcium waves to neighboring cells via gap junctions (Kenamond et al., 1997). Tendon cells subjected to equibiaxial cyclic stretching signal with a transient rise in intracellular calcium (Kenamond et al., 1998). Recently, it has been shown that connective tissue cells are responsive to fluid-induced shear stress similar to cells of the vascular system. Moreover, Brown and coworkers have shown that apparati used to apply substrate tension to cultured cells have limitations that include a potentially confounding component of fluid-induced shear stress (Brown et al., 1998). Hence, there is a concern that a given cell response to substrate stretching may actually involve a response to shear stress or some combination of the two stimuli. We have designed a parallel plate, laminar flow apparatus that provides regulated fluid-induced shear stress and subjected tendon cells to shear stresses of 0, 5, 10, 15 and 20 dynes/cm2. This will enable us to make a direct comparison between fluid-induced shear stress and substrate deformation on tendon cell signaling and downstream gene responses.
Simulation of Surface Fatigue Crack Propagation in UHMWPE Tibial Components for Total Knee Replacement
Authors: Estupiñán Jaime A. , Bartel Donald L. , Wright Timothy M.
Published: December 2021

A simulation of surface fatigue damage to ultra-high molecular weight polyethylene (UHMWPE) components in total knee replacement is presented. Results of simulations of surface fatigue crack propagation were consistent with observed clinical damage. Extensions of these analyses to incorporate a more realistic description of the constitutive and fracture behavior of UHMWPE and three dimensional geometry are discussed.
The Relationship Between Hip Simulator Wear and Surface Morphology Characterized Using White Light Interferometry
Authors: Muhlstein C. L. , Kurtz S. M. , Chui C. , Rising M. , Edidin A. A.
Published: December 2021

A non-contact surface topography measurement system based on white light interferometry was used to quantify the surface morphology of the UHMWPE, PTFE, HDPE, and polyacetal liners before and after wear testing. We investigated the hypothesis that the wear rate of four polymeric materials in the hip simulator was related to quantitative metrics of the surface morphology (i.e., surface roughness). Nine common roughness parameters (PV, Ra, Rrms, Rsk, Rku, Rtm, Rz, R3z, and H) were evaluated in 28 acetabular liners. The surface morphology within a given material was reproducible from insert to insert. Statistical relationships were observed between the surface roughness of the acetabular liners and the volumetric wear rate (p < 1 × 10−6). However, the power law relationships accounted for less than 50% of the variability in the data, based on r2.
Assessment of Orientation-Dependent Torsional Constraints Provided by a Contemporary Total Ankle Replacement
Authors: McIff Terence E. , Saltzman Charles L. , Brown Thomas D.
Published: December 2021

This paper describes torsional testing on the components of a unique total ankle design, to establish the range and conditions of torsional constraint. For this design, the torsional constraint was found to be dependent on the relative flexion and inversion angles between components. Dorsiflexion provides greater torsional stability than plantarflexion. The maximum torque values were recorded at 25 degrees of dorsiflexion with no relative inversion. Under these conditions, and with a weight bearing load of 1200 N, the ankle resisted 2200 N-mm at 5 degrees of rotation and 3300 N-mm at 15 degrees of rotation. Torsional stability decreased as the relative inversion or eversion of the components increased. When the components were inverted more than a few degrees, the initial rotational stiffness became negligible.