As all-electric aircraft has many advantages,an aircraft nose wheel steering system would be developed to the all-electric *** the control demand of the nose wheel steering system,based on the basic principles of nose...
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As all-electric aircraft has many advantages,an aircraft nose wheel steering system would be developed to the all-electric *** the control demand of the nose wheel steering system,based on the basic principles of nose wheel steering system and the design technique of mechanotronics,an all-electric aircraft nose wheel steering system,composed of a nose wheel steering mechanism of two worm gear and a control servo system of fly-by-wire with both steering and anti-shimmy functions is designed to meet the demand for operation control in the nose wheel steering ***,based on the LMS-AMESim software,the simulation model of the system is established to simulate the dynamics for the verification of its steering *** simulation results indicate that the nose wheel steering system is reasonable,and can meet the requirements of the general ***,the prototypes of the steering mechanism and control system are studied to validate the design,and the steering test bench is prepared to test the designed *** test results,such as steer angle,rotate speed of motor are analyzed in details and compared with the theoretical *** analysis and comparison results show that the design is reasonable and the property of the prototype can achieve the design objectives.
According to the composition of the electric drive system of the electric drive crawler bulldozer, the basic parameters of the main components in the electromechanical transmission system were calculated by using theo...
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Surgical instrument detection and tracking is one of the core technologies of surgical robots, which can assist clinicians in completing operations. However, existing methods need further improvement in terms of real-...
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With the expansion of a city,the urban green space is occupied and the urban heat island effect is *** the roof surfaces of urban buildings is an effective way to increase the area of urban green space and improve the...
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With the expansion of a city,the urban green space is occupied and the urban heat island effect is *** the roof surfaces of urban buildings is an effective way to increase the area of urban green space and improve the urban ecological *** provide effective data support for urban green space planning,this paper used high-resolution images to(1)obtain accurate building spots on the map of the study area through deep learning assisted manual correction;and(2)establish an evaluation index system of roof greening including the characteristics of the roof itself,the natural environment and the human society *** weight values of attributes not related to the roof itself were calculated by Analytic Hierarchy Process(AHP).The suitable green roof locations were evaluated by spatial join,weighted superposition and other spatial analysis *** the areas within the Chengdu city’s third ring road as the study area,the results show that an accurate building pattern obtained by deep learning greatly improves the efficiency of the *** roof surfaces unsuitable for greening can be effectively classified by the method of feature extraction,with an accuracy of 86.58%.The roofs suitable for greening account for 48.08%,among which,the high-suitability roofs,medium-suitability roofs and low-suitability roofs represent 45.32%,38.95%and 15.73%.The high-suitability green buildings are mainly distributed in the first ring district and the western area outside the first ring district in *** paper is useful for solving the current problem of the more saturated high-density urban area and allowing the expansion of the urban ecological environment.
In order to address the problems such as heavy weight, high cost and poor sensitivity related to the swing frame of the existing roller test system, a micro-roller dynamic balance test system based on Micro-Electro-Me...
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ISBN:
(数字)9781728148076
ISBN:
(纸本)9781728148083
In order to address the problems such as heavy weight, high cost and poor sensitivity related to the swing frame of the existing roller test system, a micro-roller dynamic balance test system based on Micro-Electro-Mechanical systems (MEMS) acceleration sensor is proposed. The MEMS accelerometer is symmetrically embedded acting as the support of the swing frame to measure the vibration acceleration. The circuit board with perforated processing is directly used as the support of the swing frame. Two wires are used to connect the sensor and the data acquisition system to avoid the interference of cable elasticity on the vibration characteristics of the swing frame. The data obtained from this test system has been processed. The influence of various interference signals in the system on the vibration measurement is identified. Vibration signals generated by imbalances are extracted from complex measurement signals. The test data show that the optimized swing frame design has smaller weight, lower cost, higher sensitivity, simpler operation and much broad application range.
A precise cylindricity error measurement system is designed for cylindricity error measurement. Firstly, three-point cylindricity error separation algorithm and cylindricity evaluation method are introduced. By elimin...
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ISBN:
(数字)9781728148076
ISBN:
(纸本)9781728148083
A precise cylindricity error measurement system is designed for cylindricity error measurement. Firstly, three-point cylindricity error separation algorithm and cylindricity evaluation method are introduced. By eliminating rotation error and random error, accurate roundness error, radius error of different sections and least square center coordinate of measured sections are calculated, which eliminates the influence of installation eccentricity on measurement results. Then, according to the three-point error measurement principle, a set of precise circle is designed. Cylindricity error measurement system, and the use of OpenGL graphics technology to reconstruct the shape of the cylinder and three-dimensional display. Finally, a number of groups of experiments were carried out on the cylinder standard parts, and the experimental results were analyzed. The results show that the system can realize cylindricity error measurement based on three-point method, which is consistent with the nominal accuracy of standard parts, and has certain application value.
We find that we made a mistake in the estimation of the H2O2 concentration by the colorimetric method in our previous paper (J. Lin et al., Eur. Phys. J. D (2020) 74: 80) [1].
We find that we made a mistake in the estimation of the H2O2 concentration by the colorimetric method in our previous paper (J. Lin et al., Eur. Phys. J. D (2020) 74: 80) [1].
In the severe high-temperature environment caused by aerodynamic heating, the vibrational excitation, dissociation and ionization of gas may successively occur, which are known as real gas effects. Under the real gas ...
In the severe high-temperature environment caused by aerodynamic heating, the vibrational excitation, dissociation and ionization of gas may successively occur, which are known as real gas effects. Under the real gas effects, the thermodynamic properties of gas vary drastically and significantly influence the performances of the active thermal protection system of hypersonic vehicles, especially in the case with coolant outflow, for example transpiration cooling. This paper numerically investigates the transpiration cooling performance with the consideration of the interaction between coolant outflow and hypersonic flow under the real gas effects. The mathematical models and coupled numerical strategy are firstly validated by experimental data, then the influences of real gas effects on the transpiration cooling of a wedged leading edge (WLE) are studied under a flight Mach number range from 8 to 12 and a flight height of 40 km. The analysis and discussions of the numerical results reveal some important phenomena and demonstrate the need to consider real gas effects.
A series of monotonic uniaxial tensile tests, strain-controlled and stress-controlled cyclic tests of SA508-3 steel were conducted from 25 to 350℃. Results showed that the steel exhibited temperature-dependent cyclic...
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A series of monotonic uniaxial tensile tests, strain-controlled and stress-controlled cyclic tests of SA508-3 steel were conducted from 25 to 350℃. Results showed that the steel exhibited temperature-dependent cyclic softening characteristic and obvious ratcheting behavior, and dynamic strain aging was observed in the range of 250-350℃. Based on experimental observations, a temperature-dependent cyclic plastic constitutive model was proposed by introducing the nonlinear cyclic softening and kinematic hardening rules, and the dynamic strain aging was also considered into the constitutive model. Comparisons between experiments and simulations were carded out to validate the proposed model at elevated temperature.
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