bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lagrangian Simulation of Gas-Solid Flows in Homogeneous Isotropic Turbulence
Authors: Huilier Daniel 
Published: November 2021

Abstract
A Lagrangian approach is developed to describe particle’s dispersion in a stationary, homogeneous and isotropic turbulent flow. Obviously, the particles’ dispersion is influenced by the fluid velocity fluctuations, which are classically simulated by a Monte Carlo process or Markov chains. However, some studies have shown the restrictions of these methods generating the fluid turbulent velocity and have suggested improvements to ensure that the Lagrangian model accounts for the three main effects governing the dispersion in gas-particle flows, namely the inertia, crossing trajectories and continuity effects. The first aim of this paper is to present an improved Lagrangian model which integrates the spatio-temporal characteristics of the fluid turbulence experienced by the particle. The agreement between the numerical results obtained and the analytical expressions derived by Wang and Stock (1993) will be very satisfying. Another interest is to investigate the role of the traditionally-neglected and troublesome added mass and history terms in numerical studies when long time dispersion of inertial particles is the primary concern. Indeed, we will observe that for a large range of values of the ratio of particle to fluid density, these non-stationary forces have statistically no influence on the characteristics of the turbulent particle dispersion and can be safely omitted.
Computational Analysis of Transient 3D-Melt-Water Interactions
Authors: Kolev Nikolay Ivanov 
Published: November 2021

Abstract
This work is part of the Siemens effort to estimate the damage potential of melt water interaction in future nuclear power plants with pressurized water reactors. After creating a modeling technology, the IVA5 computer code, verifying it by comparison with numerous separated effect tests, system tests and analytical benchmarks, performing many 2D computational analysis we present in this work complete 3D analysis of melt water interactions. Interesting conclusions for the systems analyzed are drown. Some of the limitations of the technology are also demonstrated.
The Implementation of the Level Set Method Within the Finite Element Formulation
Authors: Shepel Sergey V. , Paolucci Samuel 
Published: November 2021

Abstract
We apply the Streamline Upwind Petrov Galerkin (SUPG) finite element formulation of the Level Set method to 2D redistancing and advection problems on unstructured triangulated grids. The purpose is to test the Level Set method for mass conservation properties, where the mass is understood as the amount of fluid enclosed by the interface. For the redistancing procedure we implement the idea of mass correction suggested by Sussman and Fatemi (1999) and confirm its high accuracy within the finite element formulation. However, we find that the use of the first order SUPG formulation of the Level Set method for coupled redistancing-advection problems can result in significant loss of mass caused by distortion of the interface due to numerical diffusion. This neccesitates the use of higher order upwind finite element schemes for the advection equation.
Influence of CFD Analysis on the Design of Cooling Channels for the CCL Cavity for the Spallation Neutron Source
Authors: Konecni Snezana , Bultman Nathan K. 
Published: November 2021

Abstract
Water flow in cooling channels was simulated using the computational fluid dynamics (CFD) code CFX4. Pressure drop in the cooling channels of the coupled-cavity linac (CCL) cavity was calculated. The effects of the manifold on the pressure drop were studied also. Reducing the pressure drop was a primary goal of this exercise that led to changing the cooling channel entrance regions. Results of this analysis were used in sizing pumps required for the cooling system.
For the validation of the simplified numerical model, an experiment was performed to measure the pressure drop in the cooling channels for variable flow rate, using a flow loop. Deionized water was circulated through the test section with a pump and its flow rate was monitored with a turbine flow meter. Pressure was monitored with pressure transducers at five locations including a differential pressure transducer across the test section, and water temperature was taken at the exit of the pump.
Pressure drop across the inlet and outlet of the test section was measured and recorded for different flow rates. Flow rate was also monitored and stored simultaneously. From the recorded data, an empirical correlation was derived to describe the pressure drop, dp, as a function of flow rate through the four cooling channels.
Submerged Jet Flows of Non-Newtonian Fluids: A Computational Study
Authors: Hammad Khaled J. 
Published: November 2021

Abstract
Axisymmetric jets of non-Newtonian fluids discharging into a stagnant, identical, fluid from a wall normal to the jet axis were numerically studied. Mass and fully-elliptic momentum conservation equations governing the steady, laminar, submerged jet flow were solved using a block-implicit finite-difference scheme. The Herschel-Bulkley Theological model was used to elucidate the role of yield stress, pseudoplasticity and dilatancy, in the resulting flow structure. Use of the full equations of motion along with an accurate and efficient numerical solution technique allowed for predictions of the jet velocity profiles that are valid throughout the whole flow field. The obtained results clearly indicate the shortcomings of applying the classical boundary-layer theory to model laminar submerged jets of yield stress or shear-thinning fluids.
A Design Study of a Low-Cost Heterogeneous Parallel Computer
Authors: Barata Jorge M. M. , Silva André R. R. , Garcês Raúl L. M. 
Published: November 2021

Abstract
A design study of a low-cost heterogeneous parallel computer based on already existing hardware is presented.
The UNIX operating system is used together with PVM for message passing control. The parallel machine is constructed using existing Intel PC’s and Alpha workstation platforms.
The new techniques and algorithms are successfully applied to the grid generation problem based on the solution of partial differential equations with control of the boundary point distribution.
Two different programming models were used. One uses decomposition of the domain into as many parts as there are processors, and revealed high reductions on the total turnaround time, although load balancing was a major problem. The other programming model has the possibility of changing the position of the points of the interface between each sub-grid, and allows reductions of the total turnaround time up to 1.6 times for the case of 3 processors, while the quality characteristics of the final grid are maintained.
The communication times were reduced up to 7.5% of the total turnaround times, but the recursive nature of the numerical iterative process of the grid generation method causes a substantial increase in the number of iterations, reducing the parallel machine performance.
Implementing a Large Non-Linear Integer Optimization on a Distributed Collection of Office Computers
Authors: Nickel Ronald H. , Mikolic-Torreira Igor , Tolle Jon W. 
Published: November 2021

Abstract
We describe how we implemented the MIMERBS non-linear integer optimization methodology to run across a virtual super-computer of existing Windows NT computers networked together by an ordinary office LAN. We describe how we configured this virtual computer and how we parallelized MIMERBS to work efficiently in view of the high communications costs of our virtual computer. We also describe how we made MIMERBS highly fault-tolerant and dynamically configurable; in particular we describe techniques for handling the loss of individual computers, for automatic on-the-fly addition of new computers, and for dynamic load-balancing. We also describe the techniques we used to share computer resources gracefully with officer workers using the same computers concurrently for ordinary word and data processing.
We present performance results from specific MIMERBS applications. These examples show that performance of several gigaFLOPS is possible with just a few dozen ordinary computers on an office LAN.
Flow Characteristics of Oscillating Flow in a Channel Obstructed by an Array of Circular Cylinders
Authors: Sawada Ken-ichi , Murata Hiroyuki , Kobayashi Michiyuki 
Published: November 2021

Abstract
Flow visualization experiments on oscillating flow in a channel obstructed by an array of circular cylinders were performed. First of all, steady flow experiments without oscillation were carried out. The Karman vortices began to shed in a range of the Reynolds number: 53&lt;Re&lt;68. The Strouhal number showed a tendency to decrease with an increase of the Reynolds number. Oscillating flow experiments were carried out secondly. When the oscillation amplitude was small, Karman vortices shed periodically and its Strouhal number agreed with that in the steady flow. But, when the oscillation amplitude was large, shedding of Karman vortex was well controlled by the oscillating flow. The vortex shedding frequency became large with an increase of the cross-sectional mean velocity. On the other hand, the amplitude of velocity fluctuation in the wake was small in the accelerating phase and large in the decelerating phase.
A Self-Consistent Transient Paint Simulation
Authors: Miller Ronald H. , Strumolo Gary S. , Braslaw Jake 
Published: November 2021

Abstract
Optimizing the painting process involves understanding the many nonlinear dynamics that effect paint transfer efficiency (PTE) such as bell applicator design (bell cup and shaping air ring), operating conditions (shaping air flow rate, paint flow rate, electric potential, downdraft, and bell rotation speed), target location, and paint type. PTE optimization results in less experimental testing and improved paint quality. We have modified a numerical simulation to include self-consistent momentum coupling between a continuum and discrete mass particles, as well as the inclusion of a self-consistent electrostatic field. These modifications enable the simulation tool to address several seminal questions concerning PTE. Several simulations have been performed and the influence of self-consistent modeling is addressed in this paper.
Progress in Railroad Freight Car Engineering
Authors: Punwani Swamidas K. 
Published: November 2021

Abstract
Every year the Rail Transportation Division (RTD), American Society of Mechanical Engineers (ASME) conducts a survey to document progress in the design, construction and use of freight cars and components. This paper describes the new developments. Some information was obtained from web sites. The industry continued to focus on the evolution of freight equipment in 2000 by adding flexibility and versatility to designs developed in the recent past.
Prediction of Stiffness and Strength of Plain Weave Composites by Mixed Finite Element Method
Authors: Sihn Sangwook , Roy Ajit K. 
Published: November 2021

Abstract
A numerical model for three-dimensional stress analysis, which was formulated in the form of mixed finite element method based on Reissner’s mixed variational principle, is applied to analyze stiffness and strength of woven fabric composites. The model calculates three-dimensional effective elastic moduli and predicts failure strengths and damage modes. The failure analysis includes residual stress calculation to consider hygrothermal effect. The numerical calculations show a good agreement with existing experimental and numerical results on both flat and woven laminated composites with various yarn-waviness ratios.
Failure Mechanisms of Notched Laminates Under Biaxial Compression at Elevated Temperature
Authors: Ahn Junghyun , Waas Anthony M. 
Published: November 2021

Abstract
A compression test at elevated temperature was performed to investigate the notch sensitivity and failure mechanisms of fibrous laminated composite plates containing a stress raiser, in the form of a circular cutout, under equi-biaxial and uniaxial compressive loading. Strains measured at various locations on the specimen surface and cutout edge were used to monitor the initiation of failure. Unloading the specimen before global failure made it possible to understand the failure mechanism associated with the final failure mode.
A Comparison of Component Mode Synthesis Methods for Cyclic Structures
Authors: Tran Duc-Minh 
Published: November 2021

Abstract
Several component mode synthesis methods with fixed, free and hybrid interface are used to compute the eigen solutions and the frequency response of a cyclic structure in combination with the cyclic symmetry properties. In particular, a procedure based on the use of a truncated basis of interface modes has been developed to reduce the number of interface coordinates in the component mode synthesis methods. Both classical and new methods provide very good results and are more efficient than the use of the cyclic symmetry properties only or the combination of the cyclic symmetry with the modal projection method for computing the forced response. For the eigen solutions, the free interface methods are more accurate than the fixed and the hybrid interface methods.
A Symbolic-Numerical Method for Nonlinear Rotor Dynamics Under Fluid Confinement
Authors: Moreira Miguel , Antunes José , Pina Heitor 
Published: November 2021

Abstract
Recently, a theoretical formulation for the nonlinear planar motion of rotors under fluid confinement—motion X (t) taking place in a single direction— was developed. Using the same assumptions and methods a quite involved analytical model for nonlinear orbital motions—motions X (t) and Y (t) taking place in orthogonal directions— was also experimentally obtained and validated.
In this paper a symbolic-numerical procedure, based on a Galerkin approach, was developed to obtain an approximate nonlinear planar model for the rotor dynamics. The approximate model can be automatically generated on a symbolic computer environment, for increasing levels of accuracy. Numerical simulations showed a quite good agreement between this approximate model and the corresponding analytical exact planar model.
The proposed methodology can be used straightforward to obtain approximate nonlinear orbital rotor dynamics models, as well as for other flow-structure coupled vibratory systems.
A New Lower Extremity Modeling of Human Body With Variable Feet Links
Authors: Arafati Nader , Lazennec Jean Yves , Ohayon Roger 
Published: November 2021

Abstract
Human movement modeling has been the object of much research for the past 30 years. In these models the position of foot link was fixed on the ground.
We propose to model the feet links as variable, since the position of foot pressure center changes from heel to toes. The ground reaction forces could also be analyzed in real time. We examined this model for some static postures.
In standing anatomical position, the maximum articular forces are localized in hip and knee joints. In sagittal plane, the ground reaction force vectors are positioned nearly under ankle joints.
The pathological postures like body with pes cavus or with global spine kyphosis increase the articular and muscular forces. In these cases, the position of ground reaction force vectors is moved toward the toes.
Practical Adaptive Robust Controllers for Active Suspensions
Authors: Chantranuwathana Supavut , Peng Huei 
Published: November 2021

Abstract
This paper presents adaptive robust controllers for force tracking application in a quarter-car active suspension system. In previous publications (Chantranuwathana and Peng 1999a, 1999b), an active suspension architecture was presented. The overall active suspension system was decomposed into two loops. At the main-loop, the desired force signal is calculated while the sub-loop force tracking controller tries to keep the actual force close to this desired force. An Adaptive Robust Control (Yao and Tomizuka 1997) design technique was used to achieve good force tracking performance in a robust manner under plant uncertainties. It was found that force-tracking of up to 5Hz can be reliably achieved. It is, however, found to be unreliable in experiments, especially when high frequency disturbances are present. In this paper, we will show that unmodeled dynamics and especially, the delay (first order lag) in implementing the control signal is a main cause of the problem. With this insight, three controller modifications are proposed to reduce the effect of the unmodeled dynamics, 1) include the actuator dynamics in the ARC design, 2) cancellation of the actuator dynamics and 3) online-adaptation of an ARC parameter. A number of simulation results will be presented to show the effect of these remedies. The last two modifications were found to be promising for actual implementations.
A Knowledge-Based Tuning Method for Injection Molding Machines
Authors: Yang Dongzhe , Danai Kourosh , Kazmer David 
Published: November 2021

Abstract
Complexity of manufacturing processes has hindered methodical specification of machine setpoints for improving productivity. Traditionally in injection molding, the machine setpoints are assigned either by trial and error, based on heuristic knowledge of an experienced operator, or according to an empirical model between the inputs and part quality attributes obtained from statistical design of experiments (DOE). In this paper, a Knowledge-Based Tuning (KBT) Method is presented which takes advantage of the a priori knowledge of the process, in the form of a qualitative model, to reduce the demand for experimentation. The KBT Method is designed to provide an estimate of the process feasible region (process window) as the basis of finding the optimal setpoints, and to update its knowledge-base according to new input-output data that becomes available during tuning. The KBT Method’s utility is demonstrated in production of digital video disks (DVDs).
Adaptive Passivity-Based Nonlinear Control for Strict Feedback Form Systems
Authors: Seiler Peter , Alleyne Andrew 
Published: November 2021

Abstract
This paper presents a tracking algorithm for the adaptive control of nonlinear dynamic systems represented in Strict Feedback Form with parametric uncertainty. The construction of the stabilizing algorithm is given using Passivity-based arguments that result in an Adaptive Passivity-Based Controller (APBC). This paper also shows a comparison with a controller designed via Adaptive Backstepping with tuning functions. The Adaptive Backstepping Controller (ABC) has many additional coupling terms that make its design and implementation more complex and may also result in unwanted transients. On the other hand, the APBC has a convenient decoupling property that provides a diagnostic tool for detection of non-parametric model error.
Robust Steering and Differential Braking Control for Automated Guidance of Tractor-Semitrailer Combination Vehicles
Authors: Wang Jeng-Yu , Tomizuka Masayoshi 
Published: November 2021

Abstract
In this paper, a robust linear steering and differential braking controller is designed for the automated guidance of tractor-semitrailer combination vehicles using the H∞ loop-shaping methodology. Only the articulation angle, the lateral errors at the front and rear axle of the tractor, and the angular velocities of the rear wheels of the trailer or the brake line pressure signals, are assumed to be available for the synthesis of control inputs. The controller is designed to ensure the robustness to model uncertainties due to variations in vehicle longitudinal speed, road adhesion coefficient and trailer cargo load. Closed-loop simulation results show the robustness of the proposed controller and the resulting smaller lateral error at the trailer end when compared to the controller using the steering input only. More damped transient responses of articulation angle when using the steering and braking control also improve the yaw stability of the trailer.
Transient and Steady-State Adaptive Fueling Control of Spark Ignition IC Engines
Authors: Stroh David J. , Franchek Matthew A. , Kerns James M. 
Published: November 2021

Abstract
Presented in this paper is an adaptive, model based, fueling control system for spark ignition-internal combustion engines. Since the fueling control system is model based, the engine maps currently used in engine fueling control are eliminated. This proposed fueling control system is modular and can therefore accommodate changes in the engine sensor set such as replacing the mass-air flow sensor with a manifold air pressure sensor. The fueling algorithm can operate with either a switching type O2 sensor or a linear O2 sensor. The fueling control system is also parceled into steady state fueling compensation and transient fueling compensation. This feature provides the distinction between fueling control adaptation for transient fueling and steady state fueling. The steady state feedforward controller is comprised of two nonlinear models. These models are adapted via a recursive least squares method to accommodate product variability, engine aging, and changes in the operating environment. The transient fueling compensation also utilizes a feedforward controller that captures the essential dynamic characteristics of the transient fueling operation. This controller is measured using a frequency domain system identification approach. This proposed fueling control system is demonstrated on a Ford 4.6L V-8 fuel injected engine.
Discrete-Time LQR and H
2 Damping Control of Flexible Payloads Using a Robot Manipulator With a Wrist-Mounted Force/Torque Sensor
Authors: Lee Chunhao Joseph , Mavroidis Constantinos 
Published: November 2021

Abstract
This paper presents robust and optimal control methods to suppress vibrations of flexible payloads carried by robotic systems. A new improved estimator in discrete-time H2 optimal control design based on the Kalman Filter predictor form is developed here. Two control design methods using state-space models, LQR and H2 Optimal Design, in discrete-time domain are applied and compared. The manipulator joint encoders and the wrist-mounted six-degree-of-freedom force/torque sensor provide the control feedback. A complete dynamic model of the robot/payload system is taken into account to synthesize the controllers. Experimental verifications of both methods are performed using a Mitsubishi five-degree-of-freedom robot manipulator that carries a flexible beam. It is shown that both methods damp out the vibrations of the payload very effectively.
General Evaluation Method for Safety Control of Human-Care Robots
Authors: Ikuta Koji , Nokata Makoto , Ishii Hideki 
Published: November 2021

Abstract
In this paper, the first danger-evaluation method for use in various kinds of control strategies for human-care robots is proposed. In the case of a careless collision between a robot and a human, impact force and impact stress are chosen as evaluation values, and a danger index is defined to quantitatively evaluate the effectiveness of each safety strategy used for control. As in the previous paper on safety design, this proposed method allows us to assess the contribution of each safety control strategy to the overall safety performance of a human-care robot. In addition, a new type of robot simulation system for danger-evaluation is constructed on a workstation. The system simplifies the evaluation of danger in both the design and control of human-care robots to quantify the effectiveness of various safety strategies. Here we describe the results obtained, the successful optimization of a safety control strategy for human-care robots.