Studies on the Bidirectional Exciting Control for the Seismic Analysis of the Soil Mechanics

2010 ◽  
Vol 439-440 ◽  
pp. 811-817
Author(s):  
Yong Sang ◽  
Long Tan Shao
Keyword(s):  
High Speed ◽  
Seismic Analysis ◽  
Amplitude Ratio ◽  
Soil Mechanics ◽  
Water Pressure ◽  
Geotechnical Engineering ◽  
Servo Systems ◽  
Response Characteristics ◽  
Earthquake Load ◽  
Hydraulic Servo

According to the seismic analysis of the soil mechanics for the major and complex geotechnical engineering projects such as highway, high-speed railway, subway, dams and so on, there is acute lack testing instrument considering the level earthquake load and the vertical earthquake load. In order to resolve this problem a new design plan is putted forward in this paper, which can generate bidirectional exciting force with designed amplitude ratio, phase and waveform. The radial exciting subsystem (water pressure) and the axial exciting subsystem (force) are both built by the hydraulic servo systems. The two subsystems have excellent dynamic response characteristics. Several key technical issues existing in bidirectional exciting control have been discussed in detail such as: (1) high-precision unconventional bidirectional exciting control strategy; (2) decoupling control methods in the bidirectional exciting process; (3) real-time compensation by using digital image technology. The instrument will provide advanced test conditions for the complex geotechnical engineering.

Acceleration Detection and Inertia Compensation of Pantograph Head Using a Constant Flow Hydraulic Servo

1982 ◽  
Vol 104 (1) ◽  
pp. 8-16 ◽  
Author(s):  
T. Vinayagalingam
Keyword(s):  
High Power ◽  
Research Program ◽  
Power Output ◽  
High Speed ◽  
Low Frequency ◽  
Constant Flow ◽  
Servo Systems ◽  
Current Collection ◽  
High Power Output ◽  
Hydraulic Servo

The paper presents a novel form of acceleration detection which is suitable for use in hydraulic amplification stages for relatively low frequency, high power output servo systems. The acceleration detector was developed as part of a research program concerned with the development of a servo assisted pantograph to provide improved current collection on high speed electrified railways.

Comparison of Interstorey Drift in General RC Buildings in Pounding and No Pounding Case

2020 ◽  
Vol 2 (1) ◽  
pp. 40-47
Author(s):  
Anand Dev Bhatt
Keyword(s):  
Seismic Analysis ◽  
Linear Time ◽  
Time History ◽  
Case Analysis ◽  
Rc Buildings ◽  
Adjacent Buildings ◽  
Sufficient Distance ◽  
Earthquake Load ◽  
Interstorey Drift ◽  
Lower Height

 Inter-storey drift is an important parameter of structural behavior in seismic analysis of buildings. Pounding effect in building simply means collision between adjacent buildings due to earthquake load caused by out of phase vibration of adjacent buildings. There is variation in inter-storey drift of adjacent buildings during pounding case and no pounding case. The main objective of this research was to compare the inter-storey drift of general adjacent RC buildings in pounding and no pounding case. For this study two adjacent RC buildings having same number of stories have been considered. For pounding case analysis there is no gap in between adjacent buildings and for no pounding case analysis there is sufficient distance between adjacent buildings. The model consists of adjacent buildings having 4 and 4 stories but unequal storey height. Both the buildings have same material & sectional properties. Fast non-linear time history analysis was performed by using El-centro earthquake data as ground motion. Adjacent buildings having different overall height were modelled in SAP 2000 v 15 using gap element for pounding case. Finally, analysis was done and inter-storey drift was compared. It was found that in higher building inter-storey drift is greater in no pounding case than in pounding case but in adjacent lower height building the result was reversed. Additionally, it was found that in general residential RC buildings maximum inter-storey drift occurs in 2nd floor.

scholarly journals Internal Leakage Fault Detection and Tolerant Control of Single-Rod Hydraulic Actuators

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Jianyong Yao ◽  
Guichao Yang ◽  
Dawei Ma
Keyword(s):  
Fault Detection ◽  
Simple Structure ◽  
Control Method ◽  
Fault Tolerant ◽  
Parameter Adaptation ◽  
Servo Systems ◽  
Hydraulic Actuators ◽  
Quadratic Lyapunov Functions ◽  
Safety And Reliability ◽  
Hydraulic Servo

The integration of internal leakage fault detection and tolerant control for single-rod hydraulic actuators is present in this paper. Fault detection is a potential technique to provide efficient condition monitoring and/or preventive maintenance, and fault tolerant control is a critical method to improve the safety and reliability of hydraulic servo systems. Based on quadratic Lyapunov functions, a performance-oriented fault detection method is proposed, which has a simple structure and is prone to implement in practice. The main feature is that, when a prescribed performance index is satisfied (even a slight fault has occurred), there is no fault alarmed; otherwise (i.e., a severe fault has occurred), the fault is detected and then a fault tolerant controller is activated. The proposed tolerant controller, which is based on the parameter adaptive methodology, is also prone to realize, and the learning mechanism is simple since only the internal leakage is considered in parameter adaptation and thus the persistent exciting (PE) condition is easily satisfied. After the activation of the fault tolerant controller, the control performance is gradually recovered. Simulation results on a hydraulic servo system with both abrupt and incipient internal leakage fault demonstrate the effectiveness of the proposed fault detection and tolerant control method.

Theoretical Prediction of Motions of High-Speed Planing Boats in Waves

1978 ◽  
Vol 22 (03) ◽  
pp. 140-169
Author(s):  
Milton Martin
Keyword(s):  
High Speed ◽  
Damping Ratio ◽  
Nonlinear Effects ◽  
Theoretical Method ◽  
Valuable Insight ◽  
Response Characteristics ◽  
Theoretical Predictions ◽  
Response Amplitude Operators ◽  
Phase Angles ◽  
Good Agreement

A theoretical method is derived for predicting the linearized response characteristics of constant deadrise high-speed planing boats in head and following waves. Comparisons of the theoretical predictions of the pitch and heave response amplitude operators and phase angles with existing experimental data show reasonably good agreement for a wide variety of conditions of interest. It appears that nonlinear effects are more severe at a speed to length ratio of 6 than of, say, 4 or less, principally because of the reduction of the damping ratio of the boat with increasing speed, and the consequent increase in motions in the vicinity of the resonant encounter frequency. However, it is concluded that the linear theory can provide a simple and fast means of determining the effect of various parameters such as trim angle, deadrise, loading, and speed on the damping, natural frequency, and linearized response in waves, and that this can furnish valuable insight into the actual boat dynamics, even though the accurate predictions of large motions and peak accelerations would require a nonlinear analysis.

Historical background and evolution of Soil Mechanics

2021 ◽  
Vol 18 ◽  
pp. 96-113
Author(s):  
Philotheos Lokkas ◽  
Ioannis Chouliaras ◽  
Theodoros Chrisanidis ◽  
Dimitrios Christodoulou ◽  
Emmanouil Papadimitriou ◽  
...  
Keyword(s):  
Building Material ◽  
Soil Mechanics ◽  
Geotechnical Engineering ◽  
Rapid Development ◽  
Building Construction ◽  
Historical Background ◽  
Education Of Students ◽  
Scientific Fields ◽  
Important Branch ◽  
Over Time

The behavior of soil either as a building material or as a load receiver is particularly important and presents a paramount significance in both infrastructure and building construction. Geotechnical engineering has shown a rapid development over the last fifty years and holds a prominent position in all scientific fields of engineers. This paper mainly aims at the historical background along with the progress made on Soil Engineering as an important branch of Surveyors, Civil and Mining Engineers, where, through an important citation of technical works and constructions over time, may be considered as a significant tool for teaching and education of students

An improved model for investigating the vibration characteristics of ball bearing owing to outer race waviness under high speed

2021 ◽  
Vol 69 (2) ◽  
pp. 89-101
Author(s):  
Pingping Hou ◽  
Liqin Wang ◽  
Zhijie Xie ◽  
Qiuyang Peng
Keyword(s):  
High Speed ◽  
Ball Bearing ◽  
Vibration Measurement ◽  
Vibration Frequencies ◽  
Outer Race ◽  
Response Characteristics ◽  
Lagrange’S Equation ◽  
Rolling Elements ◽  
Initial Clearance ◽  
Improved Model

In this study, an improved model for a ball bearing is established to investigate the vibration response characteristics owing to outer race waviness under an axial load and high speed. The mathematical ball bearing model involves the motions of the inner ring, outer ring, and rolling elements in the radial XY plane and axial z direction. The 2Nb + 5 nonlinear differential governing equations of the ball bearing are derived from Lagrange's equation. The influence of rotational speed and outer race waviness is considered. The outer race waviness is modeled as a superposition of sinusoidal function and affects both the contact deformation between the outer raceway and rolling elements and initial clearance. The MATLAB stiff solver ODE is utilized to solve the differential equations. The simulated results show that the axial vibration frequency occurred at l fc and the radial vibration frequencies appeared at l fc fc when the outer race waviness of the order (l) was the multiple of the number of rolling elements (k Nb) and that the principal vibration frequencies were observed at l fc fc in the radial x direction when the outer race waviness of the order (l) was one higher or one lower than the multiple of the number of rolling elements (k Nb 1). At last, the validity of the proposed ball bearing model was verified by the high-speed vibration measurement tests of ball bearings.

scholarly journals Seismic detection of transient changes beneath Black Rapids Glacier, Alaska, U.S.A.: II. Basal morphology and processes

1999 ◽  
Vol 45 (149) ◽  
pp. 132-146 ◽  
Author(s):  
Matt Nolan ◽  
Keith Echelmeyer
Keyword(s):  
Hydraulic System ◽  
Seismic Analysis ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Basal Layer ◽  
Thick Layer ◽  
Reflection Coefficients ◽  
Overburden Pressure ◽  
Arrival Times ◽  
Black Rapids Glacier

AbstractUsing changes observed in daily seismic reflections, we have investigated the basal morphology of Black Rapids Glacier, Alaska, U.S.A. The englacial drainage of ice-marginal lakes caused significant changes in the daily reflections, as well as dramatic increases in basal motion. Changes in reflection arrival times and amplitudes indicate that there is a basal till layer at least 5 m thick at some locations beneath this surge-type glacier. Rapid changes in the observed reflection coefficients during the drainage events indicate that changes in till properties must occur throughout the entire 5 m thick layer, they must last for several days following the lake drainages and they must be completely reversible over as little as 36 min. Our seismic analysis shows that changes in effective pressure of the till are unlikely to cause the required changes in the reflection coefficients, but that a decrease in till saturation is likely. We therefore interpret the cause of the seismic anomalies as being a temporary decrease in saturation as water is input to the subglacial hydraulic system, and propose that such a change may occur quickly and reversibly by a redistribution of overburden pressure. Higher water pressures within the hydraulic system cause that region to support more of the glacier’s weight, leaving the remaining areas to support less. Any till within these areas of decreased normal stress would experience a consequent decrease in pore-water pressure, causing gas to exolve, thus decreasing saturation. This decrease in saturation would cause a change in the strength of the basal layer and may affect basal dynamics.

scholarly journals Electroluminescence and photo-response of inorganic halide perovskite bi-functional diodes

Nanophotonics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 1981-1988 ◽  
Author(s):  
Ning Li ◽  
Ying Suet Lau ◽  
Yanqin Miao ◽  
Furong Zhu
Keyword(s):  
Visible Light ◽  
High Speed ◽  
Light Emission ◽  
Forward Bias ◽  
Green Light ◽  
Visible Light Communication ◽  
Light Emitting ◽  
Response Characteristics ◽  
Photo Response ◽  
Halide Perovskite

AbstractIn this work, we report our efforts to develop a novel inorganic halide perovskite-based bi-functional light-emitting and photo-detecting diode. The bi-functional diode is capable of emitting a uniform green light, with a peak wavelength of 520 nm, at a forward bias of >2 V, achieving a high luminance of >103 cd/m2 at 7 V. It becomes an efficient photodetector when the bi-functional diode is operated at a reverse bias, exhibiting sensitivity over a broadband wavelength range from ultraviolet to visible light. The bi-functional diode possesses very fast transient electroluminescence (EL) and photo-response characteristics, e.g. with a short EL rising time of ~6 μS and a photo-response time of ~150 μS. In addition, the bi-functional diode also is sensitive to 520 nm, the wavelength of its peak EL emission. The ability of the bi-functional diodes for application in high speed visible light communication was analyzed and demonstrated using two identical bi-functional diodes, one performed as the signal generator and the other acted as a signal receiver. The dual functions of light emission and light detection capability, enabled by bi-functional diodes, are very attractive for different applications in under water communication and visible light telecommunications.

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