最新刊期
卷 54 ， 期 8 ， 2020
- 摘要：Conversion joints between single-angle and dual-angle steels are widely applied in steel pylons. Aiming at the lack of related basic theory and design specifications, the bearing capacity of conversion joints between single-angle and dual-angle steel is investigated via numerical simulation. Nine common-si-ed conversion joints are taken as the simulation examples with finite element method(FEM), and their stress state and failure mode under static tension and compressive loadings are discussed. Several design principles of component match are obtained to provide the crucial basis for the recommended design formula, the components include top single-angle and bottom dual-angle steel, vertical plates, and hori-ontal plate. The recommended design formula are then presented to evaluated the bearing capacity of conversion joints following yield line theory(YLT). It is convenient to reasonably consider certain safe reservation in virtue of the idea of -plastic analysis and elastic design-关键词：angle steel pylon;conversion joints;bearing capacity;finite element method;yield line method166|4|1更新时间：2025-07-09
- 摘要：Straw and woody biomasses are pyroly-ed in an entrained flow reactor at 1 000-1 100-1 200-1 300 - to generate soot particles and to study the oxidation reactivity of soot produced from biomass. Thermogravimetric analysis is used to study the influences of pyrolysis temperature and potassium salts on oxidation reactivity of soot particle. Results show that the oxidation activity of soot from two biomasses has different trends with the increase of pyrolysis temperature, and the oxidation activity of woody soot increases while that of straw soot decreases. The potassium content(mainly KCl)of straw is significantly higher than that of woody biomass. The significantly reduced oxidation activity of water-washed soot indicates that KCl can significantly promote soot oxidation. X-ray diffraction and particle si-e analysis show that the degree of graphiti-ation of both biomass soots increases with the increasing of pyrolysis temperature. Meanwhile the geometric mean particle si-e of primary关键词：biomass pyrolysis;formation temperature;soot;oxidation reactivity;potassium chloride136|4|4更新时间：2025-07-09
- 摘要：A combustion experiment of synthetic char is conducted in a high-temperature drop tube furnace at 1 400 K, 1 800 K in the 21% O2+79% N2 atmosphere with volume fractions of steam of 0%, 5%, 10%, 20% and 30%. The purpose is to comprehensively analy-e the influences of temperature and steam content on the gasification and volatili-ation characteristics of silica(SiO2)and the formation characteristics of ultrafine particulate matter(PM)in the process of coal char combustion. The quantity and mass concentration of ultrafine PM in the combustion products of synthetic char are measured by ELPI+, and the gasification characteristics of SiO2 are quantitatively analy-ed by using gasification factor and gasification rate. Results show that under various experimental conditions, the proportion of ultrafine PM in PM10 is more than 99%, and the mass concentration of ultrafine PM accounts for less than 1% of that of PM10. Combustion te关键词：synthetic char combustion;silica;mineral volatili-ation;ultrafine particles124|4|1更新时间：2025-07-09
- 摘要：The control volume method is used to numerically solve the temperature distribution in the solar collector and to investigate the performance of a two-dimensional solar collector with Au nanofluids. The average temperature of collector outlet is taken as the measurement standard of temperature rise. The main factors affecting the temperature rise and efficiency of the collector are analy-ed. The results show that the spectral intensity of the collector decreases greatly at the wavelength of Au plasmon resonance(about 500 nm), which proves that the effect of metal surface plasmon resonance can greatly enhance the spectral absorption characteristics, and that the degree of spectral radiation absorption in the collector affects the temperature distribution of the collector, thus affecting the temperature rise and efficiency of the collector; the efficiency of the collector is only 39.99% when pure water is used as the working fluid. Adding Au nanoparticles has higher collector efficiency关键词：plasmon resonance;collector;nanoparticles;spectral properties;photothermal conversion efficiency111|4|1更新时间：2025-07-09
- 摘要：A waste heat cascade recovery system based on thermoelectric generation/organic Rankine cycle(TEG-ORC)combined cycle is proposed to achieve efficient recovery for various waste heat of vessels. A bottom cycle ratio parameter of TEG/ORC is defined according to the waste heat utili-ation of the main engine flue gas by different bottom cycles. Through subsequent experimental research, the law of main performance parameters such as system output power, thermal efficiency, multi-stage waste heat utili-ation and cost changing with bottom cycle ratio is studied under the condition of 0.9 MPa ORC evaporation pressure. Moreover, the performance of the combined cycle system and its parameter influence are evaluated. A heat pipe enhanced heat exchange device is designed in the experiment to overcome the heat exchange bottleneck in the hot end of the TEG bottom cycle. The experimental results from three groups with different bottom cycle ratios(0.369, 0.508, 0.615)are basically consistent with sim关键词：vessel waste heat;cascade utili-ation;bottom cycle ratio;TEG-ORC combined cycle109|5|5更新时间：2025-07-09
- 摘要：A bearing fault diagnosis method using the deformation periodic potential system(DPPS)is proposed to solve the problem that the bearing fault signal is difficult to detect in a high-intensity noise environment. The method first inputs the noise-doped fault signal into the DPPS to form a stochastic resonance(SR)system with DPPS as the core and to detect the bearing fault characteristic frequency from the environmental noise and judge the bearing fault type. Then, the spectral power amplification(SPA)and amplitude response are used as measurement indicators to quantify the enhancement effect of the method on the bearing fault characteristic signal. Analytical formulas of SPA and amplitude response are derived using the method of moments and the probability flow method, and the optimal setting parameters of the DPPS diagnosis method are obtained when SPA and amplitude response are maximum. Finally, the DPPS diagnosis method is applied to the fault diagnosis of bearing inner and outer ring关键词：fault diagnosis;bearing fault;stochastic resonance;periodic potential system150|5|0更新时间：2025-07-09
- 摘要：A nonlinear profile control method for blade production process is proposed to deal with the problem that the quality control of the surface contour of production process is difficult due to the complex relationship between the profile parameters of blade body and lack of historical data. According to three-coordinate data of blade profile, the blade body profile difference metrics are constructed, and the index parameter extraction and standardi-ation processing are performed based on the measured data, which are taken as the nonlinear contour control objects. Then the classification accuracy of the difference metrics under controlled state is considered as the optimi-ation goal, and the parameters of Gaussian kernel function are optimi-ed by the adaptive particle swarm optimi-ation. The SVDD model is trained by combining the optimi-ed parameters and controlled index data to obtain the radius of the hypersphere as the control limit, and the nonlinear profile control chart based on the关键词：nonlinear profile control;difference metric;adaptive particle swarm optimi-ation;support vector data description130|4|0更新时间：2025-07-09
- 摘要：A simultaneous calibration method based on Lie group theory and iterative optimi-ation for robot orientation and hand-eye calibration is proposed to solve the problem of high precision vision measurement and position for industrial manufacturing field robots. The method uses optimi-ation after enhancing the accuracy of robot. Firstly, the pose relationships between the vision system and the robot, that is, the hand-eye relationship and the spatial conversion relationship between calibration plate and robot coordinate system, are taken as the objects for optimi-ation. The forward kinematics solution of the robot and the pose relationship between the vision system and the calibration plate are represented by a homogeneous coordinate matrix, and then a closed-loop optimi-ation equation of the hand-eye relationship of the robot is constructed. Furthermore, a three-dimensional rotation group is used to represent a rotation matrix and to establish a calibration model equation. Then the nonli关键词：robot;optimi-ation;reprojection error;model accuracy compensation174|4|6更新时间：2025-07-09
- 摘要：The interaction between NH3 and armchair graphene nanoribbons(AGNR)with different structures is studied by the first principle method to further improve the sensing performance of graphene-based gas sensors to NH3. The most stable adsorption position of NH3 on the monolayer-AGNR(MAGNR)structure and the effects of the modification to three oxyfunctional groups(hydroxyl, carboxyl, epoxy)on the sensing performance are analy-ed by calculating the adsorption energy, charge transfer and sensitivity. On this basis, the sensing performances of MAGNR structure, bilayer AGNR structure(BAGNR), MAGNR structure modified by oxyfunctional groups(MGO)and MGO, MAGNR stacking structure(MGO-MAGNR)to NH3 are studied. Results show that the adsorption of NH3 is the most stable, and the adsorption energy(-0.36 eV)and the charge transfer(-4×10-21 C)are respectively the smallest at the center of the carbon hexagon on the MAGNR structure. Mo关键词：graphene nanoribbons;first principle;sensing performance;adsorption energy138|4|3更新时间：2025-07-09
- 摘要：A wearable fabric device with the function of finger-gesture recognition is designed to solve the problem of the limited flexibility and poor combination with fabrics of the traditional strain sensors. Sensors of the device are a kind of pie-oresistive core-sheath sensing fiber composed of elastic silicon rubber and multi-wall carbon nanotubes. They are prepared by coaxial wet spinning process, and have good stitchability, high tensile strain up to 300% and fast response time less than 200 ms. They can be knitted into the finger joints of fabric gloves to sense the finger gestures. The embedded control system of the device is designed with a Single-Chip Microcomputer based on the STM32F103C8T6 main control chip to collect and to process finger gestures sensing signal. The recognition and display of finger gestures are reali-ed with functional devices including light emitting diode, passive bu--er, and organic light-emitting display. Experimental results and comparisons with the existin关键词：flexible strain sensing fiber;finger gesture recognition device;wearable fabric;embedded control system131|6|2更新时间：2025-07-09
- 摘要：To clarify the direction of demand forecast and reduce the forecast deviation, a strategy considering dynamic customer demand is proposed for material distribution. Following the historical demand of the customers, a Poisson distribution is used to simulate the changes in demand, and a demand forecasting model is established to obtain the initial forecasted demand for the customers. Then a material distribution model with uncertain demand is constructed. To solve the distribution model, a genetic algorithm with adjustable forecasting demand(GAAFD)is designed. In the local search stage of GAAFD, a demand adjustment operator is introduced. This operator adjusts the initial forecasted demand with a certain probability to obey Poisson distribution of the demand changes so that the forecasted demand can be reduced, and it simultaneously adjusts the customers between vehicles. The customers are moved to the other lowest cargo vehicle and sequenced for the vehicle service. The lowest delivery关键词：dynamic customer demand;vehicle routing problem;genetic algorithm;demand adjustment operator97|4|0更新时间：2025-07-09
- 摘要：It is difficult to dynamically determine the concentrations of volatile organic compounds(VOCs)in atmosphere of nuclear power containment, leading to a difficulty for evaluating the consequent fire disaster risk during pressure test. Six VOCs were tested qualitatively and quantitatively using an online system to obtain their dynamical volatili-ation curves and corresponding equations were fitted, and the volatili-ation rate equations were further numerically obtained. Setting 0.5 mm liquid membrane of each chemical during test, the volatili-ation periods of each chemical were calculated according to the volatili-ation rates determined in the volatili-ation rate at time 1 h and 2 h. The results suggest that as the most abundant chemical, Weidil cleaner takes23.46 h(r(t=1 h), 40 -)and33.31 h(r(t=2 h), 40 -)for volatili-ation according to the calculated results, and the tested volatili-ation period reaches 27.40 h; for screw cleaner, the calculated volatili-ation periods are49.59 h(r(t=关键词：nuclear power containment;fire disaster risk;volatile organic chemical;qualitative and quantitative test;volatili-ation period109|4|2更新时间：2025-07-09
- 摘要：Theoretical analysis and experiments based on hori-ontally installed Venturi flow meter and gamma ray sensor are carried out to correct the overreading of wet gas flow measurement caused by the existence of liquid with single differential pressure flow meter. The pipe diameter of experiment is 254 mm, test mediums are nitrogen for gas phase and kerosene for liquid phase. The inlet diameter of Venturi is 172 mm and diameter ratio is 0.58. The gamma sensor is installed at the throat of Venturi for gas void fraction measurement. The quality and gas liquid slip ratio are considered to nonlinearly fit the test data, and a new empirical correction model is obtained. Calculation results from the new model are compared with the results from modes of Murdock and Chisholm. Experimental results show that the overreading corrections calculated by the traditional Murdock and Chisholm models keep high accuracy only when Lockhart-Martinelli parameter ranges from 0.011 to 0.1, while the new empirical关键词：wet gas;overreading;gamma ray;Venturi meter116|4|1更新时间：2025-07-09
- 摘要：A GT-SUITE simulation software is used to establish a transcritical CO2 air conditioning dynamic simulation model and to find efficient control logic of automobile air conditioning. The opening of throttle, compressor speed and fan speed are taken as controlled parameter; the discharge pressure supply air temperature and cabin temperature are taken as target parameter. The influence of the startup sequence and delay time on the dynamic response performance is studied. In addition, the dynamic control response characteristics under variable ambient temperature and vehicle speeds are explored. Results and comparisons with other sequences show that proper start sequence improves dynamic response performance, and the sequence with discharge pressure-supply air temperature-cabin temperature lead the stabili-ation times of the discharge pressure and the air temperature to be shortened by 75% and 38.9%, respectively; and the ranges of opening of throttle, compressor speed, fan spee关键词：carbon dioxide;PID control;automobile air conditioning;dynamic simulation146|6|1更新时间：2025-07-09
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