The deflector jet servo valve, whose static and dynamic performance can be deteriorated by the generated flow cavitation phenomenon, is a vital segment in achieving precise control of electro-hydraulic servo valves. T...
The deflector jet servo valve, whose static and dynamic performance can be deteriorated by the generated flow cavitation phenomenon, is a vital segment in achieving precise control of electro-hydraulic servo valves. Thus, the distribution of the flow field in the pilot stage of the deflector jet servo valve has a serious impact on the performance of the valve and even the capability of the entire system. This paper is mainly presented in the three-dimensional modeling and simulation of the pilot stage flow field. For observing the characteristics of cavitation, Eulerian multiphase model, standard k-ε turbulent model, and vapor fraction transport equation model are used. The result shows that the increment of inlet pressure intensifies cavitation in the area of null clearance of the deflector jet amplifier segment and at the edge of receiving ports A & B. Moreover, large eddy simulation is used to calculate turbulent characteristics and the governing equations are solved for transient state condition to capture the characteristic of generating, growing, and merging cavity shedding phenomenon. The numerical cavitation distributions are simulated inside the deflector jet pilot stage at different oil viscosities. The result concludes that cavitation phenomenon is intensified with the decreasing of fluid viscosity. It is also observed from the numerical analysis that output pressure plays a significant role in controlling cavitation intensity around the pilot stage of the deflector jet servo valve.
The need for surveillance in a society escalates with an increase in population. As more people reside in a specified area, monitoring their activity gets tougher, which gives a rise in security concerns. Not only in ...
The need for surveillance in a society escalates with an increase in population. As more people reside in a specified area, monitoring their activity gets tougher, which gives a rise in security concerns. Not only in societies, the need for surveillance, monitoring and detection has been a prime requirement in the defence sector. This research aims in developing a surveillance and detection robot which would be capable of various applications like monitoring environment at greater distances, detecting obstacles and objects, detecting mines in the ground and achieving autonomy in traversal. All these features combined in one package will serve as a complete solution to this problem. This robot can be used for surveillance, sending live feed to a local ground station in the city. Moreover, this robot can be used in hostile situations with the armed forces. The bot can be sent to survey a particular area and provide necessary data back to the soldiers to determine safety in proceeding further. Components ranging from cameras, motors, microcontrollers, sensors, communication modules are present in the system. The robot is an integration of various subsystems working together to provide an optimum solution for surveillance and detection.
Bone can behave as a piezoelectric material, and the piezoelectric effects in bone can be associated with bone formation. However, the piezoelectric properties in cancellous bone with a complicated porous trabecular s...
Bone can behave as a piezoelectric material, and the piezoelectric effects in bone can be associated with bone formation. However, the piezoelectric properties in cancellous bone with a complicated porous trabecular structure are not sufficiently investigated because a piezoelectric signal is difficult to experimentally observe. In the author’s studies, the piezoelectric signals in air-saturated cancellous bone at 1 MHz have been experimentally observed by “a piezoelectric cell (PE-cell)”, which can correspond to an ultrasound receiver. In this study, the experimental observations of the piezoelectric signals in water-saturated cancellous bone at 1-5 MHz were performed using the PE-cell. The porosity of the bone specimen was approximately 0.65 (65%), and the network of the trabecular elements tended to be oriented in the thickness direction, which matched the ultrasound direction. The burst ultrasound waves at 1-5 MHz were received at the center of the bone specimen in the PE-cell. The output electrical signals in the PE-cell were observed. The signal amplitudes in water-saturated bone did not significantly vary with frequency, except for a larger amplitude at 2 MHz. The signal amplitudes in water-saturated bone were larger than those in air-saturated bone, and their ratios were found to vary from 6 to 32.
We propose a multi-task learning approach for estimating both the location and magnitude of damage occurring on an experimental bridge using acceleration signals collected from a passing vehicle. This is a low-cost an...
We propose a multi-task learning approach for estimating both the location and magnitude of damage occurring on an experimental bridge using acceleration signals collected from a passing vehicle. This is a low-cost and low-maintenance indirect structural health monitoring approach in which sensors on the vehicle are used to detect bridge damage. Recently, signal processing and machine learning approaches have been shown to perform well in achieving higher-level structural health monitoring objectives, such as damage localization and quantification. However, these methods not only lack robustness to measurement and model noises, but also require more physical insights. Guided by a theoretical formulation of a simple vehicle-bridge interaction system, our approach preserves the non-linearity of the trend of the acceleration signals as severity changes, and simultaneously localizes and quantifies the damage for minimizing uncertainties propagating from the location estimation. We evaluate our model on an experimental dataset. In the experiments, the damage is represented by a mass with gradually changing magnitude attached at different positions on the bridge. The results show that it can estimate locations of the damage with an accuracy of 0.08 m (3.30% of the total length of the bridge) and changes in severity level with an accuracy of 17.81 grams (8.9% of the maximum severity mass).
Mathematical optimization or mathematical programming is the selection of best one from some set of available alternatives. It is a collection of mathematical techniques and principles used for solving quantitative pr...
Mathematical optimization or mathematical programming is the selection of best one from some set of available alternatives. It is a collection of mathematical techniques and principles used for solving quantitative problems. Graph theory and Graph coloring plays a vital role in handling a computer network efficiently. A Network represented by a graph is converted into Program Dependence Graph. Maximum number of levels in a network is obtained with which minimum hop count network is determined. Graph coloring technique is used to assign colors to each node in program dependence Graph and is used to differentiate closed circuit and non – closed circuit graph.
Adhesive bonding is adversely affected by contamination on the adherend surfaces. Various surface monitoring techniques have been developed to assure that surfaces are sufficiently free from those contaminants, which ...
Adhesive bonding is adversely affected by contamination on the adherend surfaces. Various surface monitoring techniques have been developed to assure that surfaces are sufficiently free from those contaminants, which can be adsorbed on to the adherend surfaces prior to applying the adhesive and degrade bond performance. Contaminants, even at low concentrations, can pose a risk to adhesive bonding and the durability of the bonded structure. It remains a challenge to measure residual surface concentrations of critical contaminant molecules (e.g. molecules from mold release agents) by current surface control procedures. Recently, we have made advances in an existing technique, optically stimulated electron emission (OSEE), originally developed for detection of contamination on metallic surfaces. Improvements in instrument design and in measurement analysis have extended this measurement modality to low levels of molecular species of contaminants on carbon fiber reinforced polymer (CFRP) materials. In this work, we present the basics of the measurement analysis and give some typical measurement results on smooth and laser ablated surfaces. We confirm the mercury spectral absorption mechanism of the contaminant species polydimethylsiloxane (PDMS), a major component of silicone-based mold release agents. Effects of PDMS levels on adhesive bond performance through analysis of double cantilever beam (DCB) testing is shown. Service life implications from failure modes of adhesive bonding onto PDMS-contaminated surfaces are made.
The assiduous irregularity of heart beat rate might be a omen of some stern health related issues such like Tachycardia, coronary and Artery infirmity. Therefore it is acutely crucial to keep groove of one’s health b...
The assiduous irregularity of heart beat rate might be a omen of some stern health related issues such like Tachycardia, coronary and Artery infirmity. Therefore it is acutely crucial to keep groove of one’s health by auditing the rate of heart beat. As some customary approach like Electro-cardiogram (ECG) are already in use, but the usage is too convoluted and cumbersome. This demand for unique facile and modest heart rate scaling apparatus. This paper delineates the layout and operation of the equipment stationed on the fundamentals of Pulse Oximeter. This apparatus is prudent, user-friendly and low arduous device. The pursuance of the device was appraised and the outputs are correlated with the record of regular heart rate auditor by which the breach detected is minimum. The heart rate monitoring system uses a LM324 IC for the filtration and amplification of the signal which is to be processed further to get the output. The optical sensor consists of an IR Transmitter and a Photo Detector which is placed over the finger to measure the counting of the pulse. This low cost device is interfaced with Arduino which programs the device to display the heart rate. After the above system is allied to computer, there is a gratification to the user, they would be able to examine the condition of pulse rates. Besides the above mentioned features, the waveforms attained can be used for advertence in future. This would help the user to figure out and shot their heart pulse rate at home.
We have been developing an experimental method for determining the evaporation coefficient of water using a sound resonance phenomenon with the help of the theory of molecular gas dynamics. The evaporation coefficient...
We have been developing an experimental method for determining the evaporation coefficient of water using a sound resonance phenomenon with the help of the theory of molecular gas dynamics. The evaporation coefficient is one of the parameters contained in the kinetic boundary condition. The objective of the present study is to determine the evaporation coefficient by the experiment of sound resonance phenomenon. By comparing the pressure amplitude obtained from the experiments with the theoretical results based on molecular gas dynamics, we demonstrate that the evaporation coefficient of water is approximately 1.0 near 300 K.
A large number of individuals are languid in regard to workouts. They are reluctant to go out for biking. This venture gives a virtual situation to them while they do practice on indoor machines. A viable alternative ...
A large number of individuals are languid in regard to workouts. They are reluctant to go out for biking. This venture gives a virtual situation to them while they do practice on indoor machines. A viable alternative to these methods of transport that can be alluring to a wide crowd, for transport in a versatile range of environments in a protected space for exercises in cycling. This virtual space is created with Unity, a real-time cross-platform game engine which supports Virtual Reality (VR) technology. The clients can have a rich and immersive interaction with the system. The sensor attached to the stationary bicycle sends signals to the client’s cell phone by means of Bluetooth which controls the virtual vehicle on the gadget. The motion from the paddle and steering movement is tallied as the speed and direction of the virtual automobile. Low energy Bluetooth, potentiometers, gyro-sensor, reed switch, and accelerometer were used as components to make the system to achieve the mentioned tasks. The uniqueness of this innovation lies in the coherence of the system which allows the costumer to implement in almost in any paddle powered vehicle in a user-friendly manner with economic feasibility.
In our original article,1 the y-axis in Figs. 3 and 4 was mislabeled as the relative error; however, it is supposed to be a logarithm of the relative error. The
In our original article,1 the y-axis in Figs. 3 and 4 was mislabeled as the relative error; however, it is supposed to be a logarithm of the relative error. The
暂无评论