Journal of Engineering and Thermal Sciences
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Experimental study on continuous firing vibration response of the typical machine guns under different ground conditions
Get PDFIn order to study the influence of ground conditions on the continuous firing vibration response of typical machine gun, and find out under which conditions the machine gun is most stable. A high-speed photography method was used to measure the motion of multiple parts. The motion curve of each part in the shooting process are obtained, and the projectile dispersion are recorded. According to the results, the motion characteristics of each part is analyzed. The pitching and translational quasi-periodic motions of the whole gun under different ground conditions are compared by synthesizing the motion data of various parts. The working modes of gun tripod under different ground conditions are discussed, and are compared according to the corresponding projectile dispersion. The result show that, in quasi-periodic pitching motion, the upward pitching motion response of the gun under the condition of cement ground is large, the ability to restore the initial position is poor, and the corresponding vertical dispersion is the worst. Under the soil condition, the upward and downward pitching motion cycle of the gun is relatively stable, the ability to restore the initial position is strong, and the corresponding vertical dispersion is the best. In terms of quasi-periodic translational motion, the translational motion of the gun mount under the cement ground is the biggest, and the corresponding horizontal dispersion is also the biggest. Under the soil ground condition, the translational motion is the smallest, and the corresponding horizontal dispersion is also the smallest
Vibrator with two impacting pairs, one of them in the position of equilibrium
Get PDFIn the dynamic processes taking place in manipulators and robots, impact interactions play an important role. Among them two sided impacts are important. In this paper investigation of dynamic regimes of a system with two impacting surfaces, one of which is in the position of equilibrium is performed. Dynamics in steady state regime for typical parameters of the investigated system having one degree of freedom is investigated. Displacements as functions of time as well as velocities as functions of time for various positions of the impacting surface are presented. Non symmetric impacts enable to reduce the dimensions of the vibrator and to achieve increase of effectiveness of useful impacts of a manipulator. Investigations of the conservative system as well as of the system with forced harmonic excitation are performed
Extraction and recognition of music melody features using a deep neural network
Get PDFThe music melody can be used to distinguish the genre style of music and can also be used for retrieving music works. This paper used a deep learning algorithm, the convolutional neural network (CNN), to extract the features of musical melodies and recognize genres. Three-tuple samples were used as training samples in the training process. Orthogonal experiments were conducted on the number of music segments and the type of activation function in the algorithm in the simulation experiments. The CNN algorithm was compared with support vector machine (SVM) and traditional CNN algorithms. The results showed that there were obvious differences in the pitch and melody curves of different genres of music; the recognition performance was best when the number of music segments was six and the activation function was relu; the CNN algorithm trained by three-tuple samples had better recognition accuracy and spent less recognition time
A non-reference detection method of the external ultrasonic liquid level switch using the PZT
Get PDFOil tank level is an important control parameter in oil depot management. According to the principle that the liquid in the oil tank can absorb the guided wave propagation energy in the tank wall, this paper studied a non-reference detection method of external ultrasonic liquid level switch based on the signal energy change value between the current and the previously liquid level detection signal. The experimental results show that the ultrasonic guided wave with the center frequency of 30 kHz is sensitive and low misjudgment to liquid level detection. According to the experimental setup, the liquid level judgment threshold is set to 0.9890. The influence of the liquid on the guided wave propagation in the tank wall decreases with the frequency of the guided wave increase. Finally, the effectiveness of the proposed method is verified on a diesel oil tank. The research of this paper provides a method for the research of oil tank external liquid level switch technology, and provides an idea for the research of oil tank liquid level measurement based on ultrasonic guided wave
On the effect of vibrational capture of rotation of an unbalanced rotor
Get PDFThe dynamics of an unbalanced rotor with a vibrating suspension axis and driven by an asynchronous electric motor of limited power is considered. Stationary (near stationary) modes of rotation of the rotor with a frequency equal to the vibration frequency of the axis are investigated. An explanation of the phenomenon of vibrational capture of rotation of an unbalanced rotor is given. The proposed mechanical interpretation of the effect allows deeper understanding of the classical results and conclusions. The obtained condition for the existence of a stationary mode allows us to estimate the frequency capture interval of the rotor. The case when the mode of vibration capture of rotation is not set is considered. For such a case, an expression for the vibrational moment is obtained, as well as an equation for slow motions. Attention is drawn to the possibility of occurrence in the considered modes of motion of slow (relative to the rotation frequency) rotor oscillations with sufficiently large amplitudes. It is demonstrated that the vibrational capture mode has the property of self-regulation; allows to stabilize the rotation frequency of an unbalanced rotor during load oscillations. Attention is drawn to the fact that in this mode of motion, there is certainly a transfer of energy either from the source of vibration to the rotor, or vice versa. The Sommerfeld effect in an oscillatory system with an inertial vibration exciter is represented by vibration capture of rotation of the vibration exciter by resonant oscillations of the carrier body. The theoretical results are confirmed by numerical modelling
Air leakage test system for product without atmosphere air connection
Get PDFWith the air leakage test methods, the leakage tests of the products that are required to be leakproof are carried out. This leakage test starts with placing the product on a fixture. The in-ternal pressure is increased by filling compressed air into the product placed in the Fixture. The product is filled with compressed air up to a previously calculated test pressure value. After the test pressure value is reached for the desired product, the air filling process is completed, and the stabilization period begins. At the end of this period, information about the leakage of the product is obtained, depending on whether there is a change in the internal pressure of the product. In order to fill the product with compressed air, there must be an air hole on the product. Products without this air hole cannot be tested with these methods. With the new method we will develop, it will be possible to test the leakage of closed products without atmosphere-air connection
Prospects of robotics in food processing: an overview
Get PDFMechanical progressions in different spaces have widened the application skyline of advanced mechanics to an unbelievable degree. Packaging and processing are some of the important aspects involved in the food industry. As the global population continues to rise with increasing consumer demand for a wider variety of food products, food manufacturing is exploring various strategies, techniques, and methods to meet the demand and adapt to the change. Industrial robots are being integrated into every part of the food manufacturing sector to increase production rates and improve food quality and hygiene. The introduction of more stringent legislation is forcing the food sector to update its production process. On the vigorous review of 50 papers, this paper provides a comprehensive review of robotics in food processing and investigates its analysis in terms of the level of automation applied in various food processing industries. The expectation of food-Robo in the food sectors and robotics with an optimized protocol to fetch various ingredients and shape them into a final product
Automatic coordination control technology of interconnected medium voltage direct current (MVDC) distribution network based on frequency deviation
Get PDFThe automatic coordination control technology of interconnected medium voltage direct current (MVDC) distribution network based on frequency deviation is studied to improve the influence of frequency deviation on the operation of MVDC distribution network. Firstly, two regional interconnected MVDC distribution networks are built, and connected and operated in parallel with the AC power grid through the medium voltage single-phase AC port, to realize the interconnection of different regions of the distribution network according to the MVDC feeder. Through the mutual power support of each division of the distribution network, the frequency of each division of the distribution network is the same, and the frequency deviation of each division is reduced. According to the zoning frequency characteristics of the interconnected MVDC distribution network, the control strategy of the flexible interconnection device and the control strategy of the photovoltaic power generation system are combined to realize the automatic coordinated control of the frequency deviation of the interconnected MVDC distribution network. The experimental results show that this technology can improve the frequency deviation of the interconnected MVDC distribution network, realize the automatic coordinated control of the distribution network, and the fluctuation range of the tie line power deviation in each region decreases significantly
Development and analysis of thermal flow field: a new experimental approach
Get PDFA new approach to experimental investigation of thermal flow field produced along an isothermal plate of finite dimensions in free convection is presented. The experimental procedure is based upon a flow visualization technique developed earlier by author. The contribution of this paper apparently is that a physical grid placed in the light path of a photographic flow visualization system enhances the ability to discern growth of thermal flow field produced due to temperature difference between a body and its surroundings. The results obtained from flow visualization experiment are verified with a correlation predicted by earlier published work
Diagnosis of localized defects in floating bush bearings through time-frequency domain analysis
Get PDFBearings play a crucial role in the functionality of rotating machinery, and any defects in these components can result in machine failure. Detecting, diagnosing, and prognosing bearing faults are crucial steps in machine failure diagnostics to prevent malfunctions and breakdowns. While various methods exist for fault detection, including acoustic emission analysis, visual inspection, thermography, ultrasonic, motor current analysis, wear-debris analysis, oil analysis, and vibration analysis, the latter stands out as a popular non-destructive method. This paper focuses on time and frequency domain vibration analysis techniques for detecting faults in floating bush bearings. Particularly beneficial for online monitoring, remote and non-human intervention areas, and hazardous locations, the time-frequency domain approach enhances diagnostic capabilities. The vibration data collected during these experiments has been rigorously analyzed using data acquisition system and applied a comprehensive approach that includes evaluating the data in both the time and frequency domains, as well as utilizing advanced signal processing techniques, notably the high-frequency resonance technique. Test results underscore the effectiveness of specific parameters in identifying defects: waveform, form factor, parameter K, and cepstrum excel in pinpointing external defects, while kurtosis, crest factor, and skewness prove adept at identifying internal faults. In the frequency domain, the enveloped spectrum emerges as a robust method for comprehensive defect detection. The vibration data presented in this paper will prove to be an invaluable resource for professionals engaged in the field of vibration measurement and analysis