scholarly journals The temperature dependence of gradient system response characteristics

2019 ◽  
Vol 83 (4) ◽  
pp. 1519-1527 ◽  
Author(s):  
Manuel Stich ◽  
Christiane Pfaff ◽  
Tobias Wech ◽  
Anne Slawig ◽  
Gudrun Ruyters ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
System Response ◽  
Gradient System ◽  
Response Characteristics

Natural Frequency Analysis of Hydraulic Quadruped Robot and Structural Optimization of the Leg

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Qingjun Yang ◽  
Rui Zhu ◽  
Zhenguo Niu ◽  
Chen Chen ◽  
Qi Mao ◽  
...  
Keyword(s):  
Natural Frequency ◽  
Load Capacity ◽  
Structural Parameters ◽  
Multiple Input Multiple Output ◽  
State Equation ◽  
Point Of View ◽  
System Response ◽  
Response Characteristics ◽  
Research Fields ◽  
Natural Frequency Analysis

Abstract Hydraulic quadruped robots can adapt to very complex ground conditions, as they have good maneuverability and high load capacity and, therefore, have received great attention in military research fields all over the world. However, there is no mature theory on how to ensure stable, efficient, and fast walking of robots. In this paper, from the point of view of the natural frequency of the hydraulic system, we first calculate the natural frequency of the robot's legs during the whole motion period of the robot and verify the accuracy of calculation through system identification. Then, through the analysis of the state equation and transfer function matrix of the multiple-input multiple-output system, it is found that the zero and pole of the system are very close, this is why the natural frequency is low but the system response is acceptable and then we prove that no parameter for the simultaneous zero-pole cancelation of two hydraulic cylinders exists. With the goal of increasing the natural frequency, we optimized the leg structure of the robot to find the best structural parameters. Finally, a single-leg test bench was built. The experimental results show that the optimization of the structure can actually increase the natural frequency of the system and significantly improve the response characteristics of the robot.

Design of Limit-Switch Sensors Based on Discontinuity-Induced Nonlinearities

2009 ◽  
Author(s):  
Bryan Wilcox ◽  
Harry Dankowicz
Keyword(s):  
Steady State ◽  
Threshold Value ◽  
System Response ◽  
Dramatic Improvement ◽  
Low Velocity ◽  
Response Characteristics ◽  
Sensor Performance ◽  
Grazing Response ◽  
And Control ◽  
Limit Switch

Limit-switch sensors are input-output devices that switch operating state in reaction to the crossing of a threshold value of their input. These are used to monitor and control critical values of temperature, voltage, pressure, etc. in both consumer and industrial settings. This paper argues for exploiting nonsmooth fold bifurcations in the design of ultrafast and robust, resettable, electromechanical limit switches. Specifically, the discussion emphasizes the dramatic changes in system response associated with the onset of near-grazing, low-velocity contact in vibro-impacting systems. These include rapid transient dynamics away from a pre-grazing, periodic, steady-state trajectory following the onset of impacts and post-grazing steady-state trajectories with distinctly different amplitude and frequency content. The results reported here include an experimental and computational verification of the ultrafast transient growth rates that show a significant potential for dramatic improvement in sensor performance. Moreover, two novel candidate sensor designs are discussed that rely on the post-grazing response characteristics for device function. In the first instance, transduction of a change in the response periodicity following grazing in a mechanical device is detected in a coupled electromagnetic circuit. In the second instance, a snap-through post-grazing response forms the operating principle of a capacitively-driven circuit protection device.

scholarly journals Certain Type Turbofan Engine Whole Vibration Model with Support Looseness Fault and Casing Response Characteristics

2014 ◽  
Vol 2014 ◽  
pp. 1-23 ◽  
Author(s):  
H. F. Wang ◽  
G. Chen
Keyword(s):  
Coupled System ◽  
Structural Features ◽  
Fault Model ◽  
System Response ◽  
Lumped Mass ◽  
Mass Model ◽  
Turbofan Engine ◽  
Response Characteristics ◽  
Rotor Support ◽  
The Impact

Support looseness fault is a type of common fault in aeroengine. Serious looseness fault would emerge under larger unbalanced force, which would cause excessive vibration and even lead to rubbing fault, so it is important to analyze and recognize looseness fault effectively. In this paper, based on certain type turbofan engine structural features, a rotor-support-casing whole model for certain type turbofan aeroengine is established. The rotor and casing systems are modeled by means of the finite element beam method; the support systems are modeled by lumped-mass model; the support looseness fault model is also introduced. The coupled system response is obtained by numerical integral method. In this paper, based on the casing acceleration signals, the impact characteristics of symmetrical stiffness and asymmetric stiffness models are analyzed, finding that the looseness fault would lead to the longitudinal asymmetrical characteristics of acceleration time domain wave and the multiple frequency characteristics, which is consistent with the real trial running vibration signals. Asymmetric stiffness looseness model is verified to be fit for aeroengine looseness fault model.

Evidence-Theory-Based Analysis for Structural-Acoustic Field with Epistemic Uncertainties

2017 ◽  
Vol 14 (02) ◽  
pp. 1750012 ◽  
Author(s):  
Longxiang Xie ◽  
Jian Liu ◽  
Jinan Zhang ◽  
Xianfeng Man
Keyword(s):  
Interval Analysis ◽  
Interpolation Method ◽  
Epistemic Uncertainty ◽  
Computational Cost ◽  
Evidence Theory ◽  
System Response ◽  
Response Analysis ◽  
Acoustic System ◽  
Response Characteristics ◽  
Focal Element

Evidence theory has a strong capacity to deal with epistemic uncertainty, in view of the overestimation in interval analysis, the responses of structural-acoustic problem with epistemic uncertainty could be untreated. In this paper, a numerical method is proposed for structural-acoustic system response analysis under epistemic uncertainties based on evidence theory. To improve the calculation accuracy and reduce the computational cost, the interval analysis technique and radial point interpolation method are adopted to obtain the approximate frequency response characteristics for each focal element, and the corresponding formulations of structural-acoustic system for interval response analysis are deduced. Numerical examples are introduced to illustrate the efficiency of the proposed method.

Temperature dependence of frequency response characteristics in organic field-effect transistors

2012 ◽  
Vol 100 (18) ◽  
pp. 183308 ◽  
Author(s):  
Xubing Lu ◽  
Takeo Minari ◽  
Chuan Liu ◽  
Akichika Kumatani ◽  
J.-M. Liu ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Frequency Response ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Organic Field Effect Transistors ◽  
Response Characteristics ◽  
Frequency Response Characteristics

Root Locus Diagrams and the Effect of Zeros on System Response

1997 ◽  
Vol 34 (1) ◽  
pp. 48-69 ◽  
Author(s):  
J. C. Peyton Jones ◽  
D. P. Atherton
Keyword(s):  
Step Response ◽  
System Response ◽  
Minimum Phase ◽  
Root Locus ◽  
Graphical Notation ◽  
Response Characteristics ◽  
Pole Dominance ◽  
Phase Systems ◽  
Insight Into

New expressions, and a graphical notation are introduced to quantify the effect of zeros on step response characteristics. The expressions, which also hold for non-minimum phase systems, are illustrated geometrically in the s-plane, and give a more accurate insight into a concept of pole dominance than the standard ‘pure-pole’ approximations.

scholarly journals Design of Neutrosophic Self-Tuning PID Controller for AC Permanent Magnet Synchronous Motor Based on Neutrosophic Theory

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zhongliang Fu ◽  
Chunping Liu ◽  
Shengyi Ruan ◽  
Kun Chen
Keyword(s):  
Genetic Algorithm ◽  
Permanent Magnet ◽  
Pid Controller ◽  
Permanent Magnet Synchronous Motor ◽  
System Response ◽  
Permanent Magnet Synchronous Motors ◽  
Response Characteristics ◽  
Cosine Measure ◽  
Self Tuning ◽  
Different Response

In practical control applications, AC permanent magnet synchronous motors need to work in different response characteristics. In order to meet this demand, a controller which can independently realize the different response characteristics of the motor is designed based on neutrosophic theory and genetic algorithm. According to different response characteristics, neutrosophic membership functions are constructed. Then, combined with the cosine measure theorem and genetic algorithm, the neutrosophic self-tuning PID controller is designed. It can adjust the parameters of the controller according to response requirements. Finally, three kinds of controllers with typical system response characteristics are designed by using Simulink. The effectiveness of the designed controller is verified by simulation results.

Explosion Response of Cold Bond Corrosion Repairs Applied to Offshore Living Quarters

2019 ◽  
Author(s):  
Trey N. Turner ◽  
Abhimanyu Kumar
Keyword(s):  
Performance Standards ◽  
Corrosion Damage ◽  
Offshore Structures ◽  
System Response ◽  
Adhesively Bonded ◽  
Efficient Manner ◽  
Adhesive Bonds ◽  
Response Characteristics ◽  
Bonded Materials ◽  
Epoxy Adhesives

Abstract Maintaining the integrity of an aging offshore facility often requires the repair of corrosion. With advances in adhesive technology, epoxy adhesives (cold bond repairs) are increasingly being adopted to repair corrosion damage on offshore structures. Structural elements, protection barriers, and occupied buildings, for example a platform living quarters, designated as safety critical often must comply with project or facility performance standards that specify minimum design accidental loading (e.g., from fire, explosions, or impact). In addition to satisfying conventional structural design criteria, a corrosion repaired structure must also perform within acceptable limits when subjected to accidental loads. The present study outlines approaches to assess the performance of cold bond repairs subjected to accidental explosion loads. The living quarters considered in this study featured approximately 50 individual cold bond repairs; each arbitrarily located over the building’s external surfaces. Under accidental blast conditions, failure of a cold bond repair was deemed unacceptable due to the threat of pressure leakage into the building’s interior. As such, the study demanded an analysis capable of considering both the global response of the living quarters as well as the local response of cold bond repairs. There have been several studies conducted by researchers around the globe to evaluate the response characteristics of adhesive bonds. However, these studies are largely focused on experimental, local, and micromechanical analysis of adhesively bonded materials. Numerical analysis of adhesive bonds, for purposes of global structural system response assessments, especially in the case of accidental loading, appear to be nonexistent in available literature. Inspired by this gap, we present a case study involving an assessment of global structural performance of a living quarters building repaired with cold bond adhesives subject to loading due to accidental and rare events. In this study, the local behavior of cold bond adhesives was calibrated using numerical simulations of the ASTM tests specified by the adhesive vendor. The calibrated properties were implemented in finite element analyses used to validate cold bond seal plate repairs at various locations on the living quarters building. The study includes a discussion about the methods and approaches used to model cold bond repairs in a practical and efficient manner. The approach outlined herein provides a useful framework that can be adapted to similar assessments by a practicing engineer responsible for blast analysis of marine structures.

Passive Nonlinear Vibrations of a Directly Excited Nanotube-Reinforced Composite Cantilevered Beam

2005 ◽  
Author(s):  
S. N. Mahmoodi ◽  
Nader Jalili ◽  
S. E. Khadem
Keyword(s):  
Frequency Response ◽  
Multiple Scales ◽  
Damping Ratio ◽  
High Carbon Steel ◽  
Nonlinear Resonance ◽  
Excitation Amplitude ◽  
Viscoelastic Layer ◽  
System Response ◽  
Response Characteristics ◽  
Reinforced Composite

This paper undertakes the passive nonlinear vibration analysis of a directly excited composite cantilever beam modeled as an inextensible Euler-Bernoulli beam. The composite beam consists of two elastic layers of high-carbon steel sandwiched together through a viscoelastic layer of carbon nanotube (CNT)-epoxy mixture. The resulting viscoelastic damping is modeled as Kelvin-Voigt damping model, with the nonlinearities present due to inextensibility assumption. In order to study the system response characteristics, the method of multiple scales is employed to arrive at the modulation equations and the closed-loop frequency response function. Such analytically-derived frequency response is experimentally verified through harmonic force excitation of samples of CNT-reinforced composite beams. The results demonstrate that increasing the excitation amplitude or decreasing damping ratio can cause a minor decrease in the nonlinear resonance frequency despite the significant increase in the amplitude of vibration due to reduced damping.

Temperature dependence and response characteristics of the isolated wing hinge stretch receptor in the locust

1989 ◽  
Vol 165 (2) ◽  
pp. 247-252 ◽  
Author(s):  
H. K. Pfau ◽  
U. T. Koch ◽  
B. Möhl
Keyword(s):  
Temperature Dependence ◽  
Stretch Receptor ◽  
Response Characteristics
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