bluuebunny/crossref_metadata_2025_split huggingface dataset:
Partial Model Based Walking Control of Quadruped Locomotion Robot With Self Renovation Control Function
Authors: Uchida Hiroaki , Nonami Kenzo , Iguchi Yoshihiko , Jiu Huang Qing , Yanai Takaaki 
Published: February 2021

Abstract
It is considered that locomotion robots are aggressive under the circumstances where human hardly work, for example, in the nuclear power plant, in the bottom of the sea and on a planet. The injury and the fault of the robot might occur frequently under those circumstances. It is very important problem that the robot can realize the walking with the fault. This is very difficult problem for biped and quadruped robot to realize a stable walking in the case that actuator or sensor is broken. And, in walking of mammal, gait pattern is generated by neural oscillator existing in the spinal cord. In the case that a lower neural system is injured, mammal realize a walking by a higher neural system. Thus, mammal has a self renovation function. In this study, in order to realize the stable walking of the quadruped robot with fault, we discuss the control method with self renovation function for the fault of the decentralized controller and the angular sensor. First, we design the centralized controller of one leg by sliding mode control for the fault of decentralized controller. Second, Sky Hook Suspension Control is applied for the fault of the angular sensor. The proposed methods are verified by 3D simulations by CAD and experiments.
A Modal Filtering Approach for Active Vibration Control of High-Rise Structures Using Smart Sensors
Authors: Sivrioglu Selim , Kikushima Yoshihiro , Tanaka Nobuo 
Published: February 2021

Abstract
In most real structures such as buildings, bridges and others, the fundamental frequency is lower than 1 Hz, and it is generally enough to control such mode or modes to avoid damages of earthquakes. The well-known approach using point sensors and active mass dampers is employed to control vibration in high-rise structures. The effectiveness of this conventional approach can be disappointing when earthquake-like excitations are in question. Therefore, the development of actuators and sensors are particularly important for effective structural control.
Experiments of Active Tendon Control of Space Trusses
Authors: Bossens Frédéric , Preumont André 
Published: February 2021

Abstract
After a brief review of the strategy for damping cable structures with active tendons and a summary of the linear theory allowing to predict the closed-loop poles with a root locus technique, the paper presents experimental results obtained with two trusses. The first one is an active truss, clamped at its base and equipped with three guyed cables with active tendons; the second one is a free floating truss of geometry similar to the JPL Micro-Precision Interferometer; the three elementary trusses are connected by cables with active tendons. The experimental results tend to confirm the root locus predictions of the closed-loop poles.
Optimal Control of a Flexible Mechanism Using a Combined Feedforward-Feedback Strategy: Simulation and Experiment
Authors: v. Stein Hubertus , Ulbrich Heinz 
Published: February 2021

Abstract
Due to the elasticity of the links in modern high speed mechanisms, increasing operating speeds often lead to undesirable vibrations, which may render a required accuracy unattainable or, even worse, lead to a failure of the whole process. The dynamic effects e.g. may lead to intolerable deviations from the reference path or even to the instability of the system. Instead of suppressing the vibration by a stiffer design, active control methods may greatly improve the system performance and lead the way to a reduction of the mechanism’s weight. We investigate a four-bar-linkage mechanism and show that by introducing an additional degree of freedom for a controlled actuator and providing a suitable control strategy, the dynamically induced inaccuracies can be substantially reduced. The modelling of the four-bar-linkage mechanism as a hybrid multi body system and the modelling of the complete system (including the actuator) is briefly explained. From the combined feedforward-feedback optimal control approach presented in (v. Stein, Ulbrich, 1998) a time-varying output control law is derived that leads to a very good system performance for this linear discrete time-varying system. The experimental results show the effectiveness of the applied control strategy.
Finite Element Modeling of a High Speed Optical Depth Scanner
Authors: Szydlo J. , Lehmann R. , Lassen T. , Bleuler H. 
Published: February 2021

Abstract
A rotational high-speed depth scanner for an optical low-coherence reflectometer used for 3-D retina scanning has been developed and analyzed. A rotational speed of 427’000 rpm (in the range between the 4th and 5th critical speed) has been reached for the 5 × 5 × 2 mm3 BK7 glass cube, resulting in a record scan rate for this kind of instrument. This paper reports on our experimental results as well as the FE-modeling of the rotor and the internal-reflection glass cube under centrifugal stress, and on the interplay of mechanical deformation and optical performance. The scanner is mounted on air bearings and driven by an air turbine.
Developments of the Hydraulic Driving System of the Control Rods for Nuclear Reactors
Authors: Wu Yuanqiang 
Published: February 2021

Abstract
The developments of a new hydraulic driving system of the control rods for nuclear reactors are introduced in this paper. Compared with other driving systems of the control rods, this new hydraulic driving system can be set within the reactor pressure vessel. Under any serious condition, the control rods will not be ejected from the reactor core. Its structure is very simple and the mechanic chain is very short, and thus it is very reliable. It can reduce the height of the nuclear reactor by one-third, and thus dramatically reduce the cost of the reactor. It uses the dynamic hydraulic pressure to control the motion of the control rods. Under extreme conditions, such as the failure of control power supply, the control rods will drop into the reactor core because of their self-weight to shut down the nuclear reaction. Because of these features, International Atomic Energy Agency (IAEA) is very interested in this safe and economical new control rod driving system. A brief history of the developments of the hydraulic driving system is given. Three configurations, the orifice hydraulic step cylinder, the groove-orifice hydraulic step cylinder, and the piston-groove hydraulic step cylinder, are introduced and their working principles are explained. The reliability and safety of the new system are validated by two experimental works: hydraulic step cylinder (HSC) under seismic and rocking conditions. Results from these experiments are presented.
Tension and Speed Regulation of Axially Moving Materials
Authors: Nagarkatti Siddharth P. , Zhang Fumin , Rahn Christopher D. , Dawson Darren M. 
Published: February 2021

Abstract
In this paper, the tension and speed of an axially moving material system are regulated using control torques applied to rollers at each end of a controlled span. Given a distributed parameter model, Lyapunov-type arguments produce a model-based boundary control law that exponentially stabilizes the material tension and speed at the desired setpoints. Dynamic simulation results compare the tension and speed setpoint regulation provided by the proposed control strategy with standard PID approaches.
Monte Carlo Simulation of Grain Growth at Heat Affected Zone (HAZ) of Weldment
Authors: Jahanian S. , Lei Wen 
Published: February 2021

Abstract
Average grain size and grain size distribution at HAZ is the dominant microstructural features of weldment. Such features may govern many properties of the weldment, such as strength, ductility, toughness, corrosion resistance and so forth. Accordingly, prediction of the final grain size and grain distribution is crucial to a welding engineer. The nature of grain growth in the weldment is known to be stochastic. Hence, using a deterministic method for predicting the final grain size of weldment should be reconsidered.
In this paper Monte Carlo simulation of grain growth at Heat Affected Zone (HAZ) of a 0.5 Mo-Cr-V steel is presented. The technique used for this simulation is discussed. We also use a methodology to obtain a one-to-one correlation between Monte Carlo (MC) and real parameters of grain size and time. The results are compared with the experimental results and a reasonable agreement is observed.
To carry out the simulation, we generate a random 200*200 matrix. Each element of this matrix represents a grain site with a unique grain orientation at the beginning of the simulation. We run the simulation for both bulk heating situation and HAZ zone to decide the thermal pinning effect. In the case of HAZ. zone, the center of this matrix represents the fusion zone of the HAZ. Periodic boundary conditions are used so that the grains wrapping around are at the same temperature. To make a comparison, we look at a HAZ location about 120 microns from the fusion zone and compare it with the grain size obtained in an actual weld HAZ at an identical location.
The simulation result shows a near match with the experimental data for bulk heating. The grain structure of the simulation result in the weld HAZ also has a reasonable accuracy. It can be concluded that the MC technique could effectively capture the thermal pinning existing in the weld HAZ. The difference between the simulation result and the experimental data suggest the effect of thermal pinning is higher than the effect based on the thermal gradient alone.
One Decade of Holospectral Technique: Review and Prospect
Authors: Qu Liangsheng , Xu Guanghua 
Published: February 2021

Abstract
The holospectrum is a FFT based spectrum. It integrates the spectra of the vibration signals in one or more bearing sections of a rotor. This paper summarizes the experience in application of the holospectral technique to diagnose the potential faults of large rotating machinery, its key technique, recognition ability and other advantages. Further potential applications of this technique in rotor balancing, performance evaluation and long range forecasting of large rotating machinery are envisaged.
Accumulator Roll Analysis Using the Finite Element Method
Authors: Pierson Hazel M. , Suchora Daniel H. , Viviano Anthony V. 
Published: February 2021

Abstract
The purpose of this study was to develop a method to analyze various designs of non-driven accumulator rolls using a static finite element software package. This would allow the engineer to determine how the various components of the roll design contribute to or lessen the deflection of and stresses in the roll body when it is loaded by sheet metal passing over o under it. The method outlined is intended mainly for use when an advanced dynamic finite element package that incorporates contact elements is not available and when a comparison of various roll designs is desired.
First, an approximation of the pressure on the roll body caused by the force of the sheet metal as it wrapped over or under the roll was determined. Then using the finite element package ALGOR, an FEA model of a standard accumulator roll design was loaded with this pressure and the stresses and deflections were calculated. Next, components of this basic roll design were varied in the FEA model. These were the location of the stiffeners and the thickness of the roll body, the end plates, and the stiffeners. A comparative approach was then used to assess the impact each of these variations in roll design had oh the deflection of and the stresses in the roll.
Commercial Walk-Behind Lawn Mower Failure Analysis Case Study
Authors: Brickman Dennis B. 
Published: February 2021

Abstract
A failure modes and effects testing program was conducted to analyze the cause of a mid-size commercial walk-behind lawn mower accident in which the operator’s foot came in contact with the rotating blade. Systematic analysis showed that the accident was caused by improper mower service and operator misuse of the mower. Testing results reveal that an alternative design proposal does not preclude this random event. Accident prevention countermeasures are explored.
Minimally Invasive Suturing Device
Authors: Fudge Brian M. , Verkade Drew 
Published: February 2021

Abstract
The design of an intracorpeal suturing device that will assist surgeons in placing an internal suture through a small incision. Performing surgical procedures through a small incision greatly reduces patient trauma and rehabilitation time, both of which are proportionally related to medical costs. Medical devices exists today that allow surgeons to perform procedures through small incisions, unfortunately, it is difficult to place sutures deep in the body using minimally invasive techniques. A device that enables surgeons to place sutures minimally invasively will facilitate surgeons by increasing the scope of procedures that can be preformed using this technique.
Patents: Restoring Safety
Authors: Barnett Ralph L. 
Published: February 2021

Abstract
The law punishes manufacturers who embrace safely innovation and product improvement. The “new” is literally the enemy of the “old” in the sense that a new safety design may be used by the law to show that all past and current designs are defective. On the other hand, if the new design is patented, a special attribute precludes its invocation as a remedial measure for a safety problem which predated the patent.
Ladder Slide Out: First Order Analysis
Authors: Barnett Ralph L. 
Published: February 2021

Abstract
One of the more important collapse modes for straight, combination, and extension ladders is base slide out; the top of the ladder slides down the support wall as the base slips away from it. Various fundamental models have been used to study this behavior. This paper revisits the analytical solutions associated with these models and describes their implications for the analysis, design, and testing of ladders.
Trencher: Impingement on Buried Objects
Authors: Brickman Dennis B. , Barnett Ralph L. 
Published: February 2021

Abstract
There is a resemblance between the digging chain of a trencher and the folklore chain saw. The safety of trenchers requires that the similarities and differences between these two machines be understood so that appropriate warning signs can be formulated. There is a notion that the trencher can be suddenly thrust rearward in the direction of the digging chain in the manner associated with the chain saw. There is also a notion that the kickback characteristic of the chain saw is also characteristic of a trencher digging chain. This paper shows that these rearward thrust and kickback notions for the trencher are false. On the other hand, contact with moving teeth is hazardous on either machine.
Symmetrical Motions of Tensegrity Structures: A Reconfiguration Procedure
Authors: Sultan Cornel , Skelton Robert E. 
Published: February 2021

Abstract
In this paper we derive the nonlinear equations of motion for tensegrity structures and cast them in vector second order form. For certain tensegrity structures a particular class of motions, coined symmetrical motions, is defined. The corresponding equations of motion are presented and the conditions under which symmetrical motions occur are established. A reconfiguration procedure through symmetrical motions is proposed and examples of its application are given.
Coupling Finite Element Method and Perturbation Techniques for Non Linear Vibrations of Plates
Authors: Azrar L. , Benamar R. , Potier-Ferry M. 
Published: February 2021

Abstract
The effectiveness of the coupling of the perturbation techniques and the finite element method has been demonstrated using a method called Asymptotic-Numerical Method (ANM). This concept eliminates the major difficulties of the classical perturbation methods namely the complexity of the right hand sides and the limitation of the validity of the solution obtained. In this paper we present the development of this method and its applicability for large amplitudes free vibrations of plates. The displacement and the frequency are expanded into power series with respect to a control parameter. The nonlinear governing equation is transformed into a sequence of linear problems having the same stiffness matrix. Needing one matrix inversion, a large number of terms can be computed with a small computation time. Taking the starting point in the zone of validity, the method is reapplied in order to determine a further part of the nonlinear solution. In order to increase the zone of validity, the Pade approximants are incorporated. Iterations of this method lead to a powerful incremental method. Numerical tests for large amplitudes free vibrations of plates with various shapes and boundary conditions are reported. Recent improvements in the basic ANM algorithm as well as applications to various structural problems are added in order to exhibit the effectiveness and the applicability of this method.
Stabilization of Mechanical Structures With Distributed Sensors and Actuators: A Hamiltonian Approach
Authors: Schlacher Kurt , Kugi Andreas 
Published: February 2021

Abstract
Intelligent mechanical structures based on piezoelectricity form an important new group of actuators and sensors for active vibration control. Since this technology allows to construct spatially distributed devices, new design possibilities for the control systems open up. Now the design of the spatially distributed sensors and actuators becomes part of the controller design itself. Several well established approaches, like the PD-, H2- and H∞-design are adapted to solve this problem. They are based on infinite dimensional Hamiltonian systems in conjunction with collocated actuator and sensor pairing. Since this approach is based on the so called Poisson bracket only, one can unify the controller design for finite and for infinite dimensional systems. Of course, the stability investigations are much more complicated in the latter case. Finally, applications to beams and plates demonstrate the power and effectiveness of the proposed methods.
Design of Dynamical Controllers for Linear Hamiltonian Systems
Authors: Haas Werner , Krommer Michael , Irschik Hans 
Published: February 2021

Abstract
Linear Hamiltonian control systems with collocation of sensor and actuator are considered. Based on a frequency domain approach a controller design algorithm is stated. The design leads to a controller with internal dynamics which uses the output of the system and its first time derivative. The presence of internal dynamics in the controller is an extension of the usual PD–control law and a main result of the work. The design is based on the special properties of the proposed class of systems. In particular, these Hamiltonian systems are passive. It is shown that the design leads to strictly passive controllers for a certain choice of the design parameters. This is another significant result and offers a way for robust ℒ2–stabilization even in the case of infinite dimensional systems. Some features of the controller design are discussed with respect to an application, the control of a composite circular plate.
Effects of Harmonic Intentional Mistuning on the Free Response of Bladed Disks
Authors: Brewer Michael E. , Castanier Matthew P. , Pierre Christophe 
Published: February 2021

Abstract
In this paper, the free response of bladed disks with intentional mistuning is considered in detail. A simple lumped-parameter model of a bladed disk is employed. Intentional mistuning is included by applying a sinusoidal variation to the nominal blade stiffnesses. It is shown that if the intentional mistuning harmonic number and the number of blades have a common integer factor greater than one, then the eigenvalue problem reduces to a set of smaller problems. It is found that the ratio of intentional mistuning strength to the interblade coupling strength is a key parameter for the free response. As this ratio increases, the modes become localized. More importantly, the modes of the intentionally mistuned system have several non-zero nodal diameter components, in contrast to the tuned system which has pure nodal diameter modes. Furthermore, if only random mistuning is present, each mode of the bladed disk assembly still retains a strong nodal diameter component. However, the modes of the system with intentional mistuning and random mistuning tend to have more evenly distributed nodal diameter components. This shows why intentional mistuning can be effective in reducing the maximum blade forced response for engine order excitation.
Analog Simulation of Phase Locked Modes of Diffusively Coupled van der Pol Oscillators
Authors: Low Lesley Ann , Reinhall Per G. , Storti Duane W. 
Published: February 2021

Abstract
Limit cycle oscillators arise in a wide variety of mechanical, electrical and biological systems. Recently, emphasis has been placed on the study of systems of coupled limit cycles, such as cardiac oscillations. Synchronization criteria have remained a focus of most investigations.
One area of investigation in the field of coupled limit cycles is studying the behavior of a pair of linearly coupled van der Pol oscillators (Low, 1998; Rand, 1980; Sliger, 1997). Previous investigations (Storti, 1993; Storti, 1996) found the stability regions of the coupled oscillators for their in-phase and out-of-phase modes numerically.
The coupled oscillators can be viewed as a mechanical system, where the coupling parameters are equivalent to a spring and damper attached between two masses. With positive coupling (positive damping) a region was found (Storti, 1993; Storti, 1996) where the in-phase mode is unstable. This counter intuitive result is yet to be discovered in a physical system of two coupled limit cycle oscillators. This research focuses on finding the region with positive coupling parameters where the in-phase mode is unstable using a physical model of two linearly coupled van der Pol oscillators. The coupled van der Pol oscillators were modeled using an analog electric circuit.
A Non Parametric Model for Magneto Rheological Dampers
Authors: Ahmadian Mehdi , Song Xubin 
Published: February 2021

Abstract
A non-parametric model for magneto-rheological (MR) dampers is presented. After discussing the merits of parametric and non-parametric models for MR dampers, the test data for a MR damper is used to develop a non-parametric model. The results of the model are compared with the test data to illustrate the accuracy of the model. The comparison shows that the non-parametric model is able to accurately predict the damper force characteristics, including the damper non-linearity and electro-magnetic saturation. It is further shown that the parametric model can be numerically solved more efficiently than the parametric models.
Static and Dynamic Characterization of Tensegrity Modules
Authors: Murakami Hidenori , Nishimura Yoshitaka 
Published: February 2021

Abstract
A set of procedures was presented for characterizing static and dynamic response of tensegrity modules. The procedures were applied to two tensegrity modules: a six-bar spherical module and a two-stage cylindrical module with three bars at each stage. The singular value decomposition of the initial equilibrium matrix revealed pre-stress and infinitesimal mechanism modes. The pre-stress stiffening effect of mechanism modes was found to be isotropic at each node. In the initial quasi-static loading, infinitesimal mechanisms exhibited soft response. As the deformation advanced, the stiffness of tensegirty modules increased almost quadratically with infinitesimal mechanism-mode amplitudes. Modal analyses revealed that the lowest modes were those of mechanism modes and their natural frequencies were an order of magnitude smaller than those of higher deformation modes.