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31.
Xuan-Tao Ji Si-Yuan Luo Yu-He Huang Kun Zhu Jin Zhu Xiao-Yu Peng Min Xiao Xiao-Dong Wang 《核技术(英文版)》2022,33(1):13-23
The muon radiography imaging technique for high-atomic-number objects(Z) and large-volume objects via muon transmission imaging and muon multiple scattering imaging remains a popular topic in the field of radiation detection imaging. However, few imaging studies have been reported on low and medium Z objects at the centimeter scale. This paper presents an imaging system that consists of three layers of a position-sensitive detector and four plastic scintillation detectors. It acquires data by co... 相似文献
32.
GAP是世界农产品生产规范的认证,我国虽已经在农产品企业加工中运用,但运用还需继续深入。对农产品加工企业应用的分析,是根据综合调查各企业的基本情况,以及实际应用后带来的效益,给出促进GAP认证推广与发展的建议。 相似文献
33.
Jie-Hui Yuan Sheng Zhou Tian-Duo Peng Ge-Hua Wang Xun-Min Ou Hua-Ping Sun Wei-Feng Sun Yong Geng Yu-Sheng Kong 《石油科学(英文版)》2018,15(3):644-656
This study develops a bottom-up model to quantitatively assess the comprehensive effects of replacing traditional petroleum-powered vehicles with natural gas vehicles (NGVs) in China based on an investigation of the direct energy consumption and critical air pollutant (CAP) emission intensity, life-cycle energy use and greenhouse gas (GHG) emission intensity of NGV fleets. The results indicate that, on average, there are no net energy savings from replacing a traditional fuel vehicle with an NGV. Interestingly, an NGV results in significant reductions in direct CAP and life-cycle GHG emissions compared to those of a traditional fuel vehicle, ranging from 61% to 76% and 12% to 29%, respectively. Due to the increasing use of natural gas as a vehicle fuel in China (i.e. approximately 28.2 billion cubic metres of natural gas in 2015), the total petroleum substituted with natural gas was approximately 23.8 million tonnes (Mt), which generated a GHG emission reduction of 16.9 Mt of CO2 equivalent and a CAP emission reduction of 1.8 Mt in 2015. Given the significant contribution of NGVs, growing the NGV population in 2020 will further increase the petroleum substitution benefits and CAP and GHG emission reduction benefits by approximately 42.5 Mt of petroleum-based fuel, 3.1 Mt of CAPs and 28.0 Mt of GHGs. By 2030, these benefits will reach 81.5 Mt of traditional petroleum fuel, 5.6 Mt of CAPs and 50.5 Mt of GHGs, respectively. 相似文献
34.
In this paper the control mechanism of solenoid valve is analyzed, which shows the solenoid valve control is actually the control of coil current. The response characteristic of coil current is related to coil inductance and resistance. The coil resistance is influenced greatly by the ambient temperature and the self-heating of coil, which affects the control precision of coil current. First, considering the heat dissipation mode of coil, the coil temperature model is established from the perspective of heat conduction, and a temperature compensation algorithm for hydraulic system pressure control is put forward. Then the hardware-in-the-loop testbed is set up by using the dSPACE platform, carrying out wheel cylinder pressurization tests with inlet valve fully opened at -40℃ and 20℃, and testing the actual pressure of wheel cylinder with the target pressures at -40℃ and 6.000 kPa/s (pressurization rate). The results show that the pressure control temperature compensation algorithm proposed in this paper accurately corrects the influence of resistance temperature drift on the response accuracy of wheel cylinder pressure. After the correction, the pressure difference is less than 500 kPa, which can meet the control accuracy requirements of solenoid valve, enriching the linear control characteristic of solenoid valve. 相似文献
35.
36.
Frontiers of Mechanical Engineering - Experimental and finite element research was conducted on the bolted interference fit of a single-lap laminated structure to reveal the damage propagation... 相似文献
37.
This paper studies a distributed policy evaluation in multi-agent reinforcement learning. Under cooperative settings, each
agent only obtains a local reward, while all agents share a common environmental state. To optimize the global return as
the sum of local return, the agents exchange information with their neighbors through a communication network. The mean
squared projected Bellman error minimization problem is reformulated as a constrained convex optimization problem with
a consensus constraint; then, a distributed alternating directions method of multipliers (ADMM) algorithm is proposed to
solve it. Furthermore, an inexact step for ADMM is used to achieve efficient computation at each iteration. The convergence
of the proposed algorithm is established. 相似文献
38.
It is well-known that microscale gaps or defects are ubiquitous and can be penetrated by vapor,resulting in the failure of superhydrophobic effect and undesired condensate flooding under high subcooling.Here,we propose and demonstrate that such problem can be solved by the oblique arrangement of nanowires.Such a structure has been demonstrated to own anti-vapor-penetration and microdrop self-transport functions under high subcooling,unaffected by the microscale gaps.This is because vapor molecules can be intercepted by oblique nanowires and preferentially nucleate at near-surface locations,avoiding the penetration of vapor into the microscale gaps.As-formed microdrops can suspend upon the nanowires and have low solid-liquid adhesion.Besides,oblique nanowires can generate asymmetric surface tension and microdrop coalescence can release driving energy,both of which facilitate the microdrop self-removal via sweeping and jumping ways.This new design idea helps develop more advanced condensation mass and heat transfer interfaces. 相似文献
39.
Intelligent reflecting surfaces(IRSs)constitute passive devices,which are capable of adjusting the phase shifts of their reflected signals,and hence they are suitable for passive beamforming.In this paper,we conceive their design with the active beamforming action of multiple-input multipleoutput(MIMO)systems used at the access points(APs)for improving the beamforming gain,where both the APs and users are equipped with multiple antennas.Firstly,we decouple the optimization problem and design the active beamforming for a given IRS configuration.Then we transform the optimization problem of the IRS-based passive beamforming design into a tractable non-convex quadratically constrained quadratic program(QCQP).For solving the transformed problem,we give an approximate solution based on the technique of widely used semidefinite relaxation(SDR).We also propose a low-complexity iterative solution.We further prove that it can converge to a locally optimal value.Finally,considering the practical scenario of discrete phase shifts at the IRS,we give the quantization design for IRS elements on basis of the two solutions.Our simulation results demonstrate the superiority of the proposed solutions over the relevant benchmarks. 相似文献
40.