Proton irradiation effect on SCDs

The Low Energy X-ray Telescope is a main payload on the Hard X-ray Modulation Telescope satellite. The swept charge device is selected for the Low Energy X-ray Telescope. As swept charge devices are sensitive to proton irradiation, irradiation test was carried out on the HI-13 accelerator at the China Institute of Atomic Energy. The beam energy was measured to be 10 MeV at the SCD. The proton fluence delivered to the SCD was $3\times10^{8}\mathrm{protons}/\mathrm{cm}^{2}$ over two hours. It is concluded that the proton irradiation affects both the dark current and the charge transfer inefficiency of the SCD through comparing the performance both before and after the irradiation. The energy resolution of the proton-irradiated SCD is 212 [email protected] keV at $-60\,^{\circ}\mathrm{C}$, while it before irradiated is 134 eV. Moreover, better performance can be reached by lowering the operating temperature of the SCD on orbit

Swept blade influence on aerodynamic performance of steam turbine nozzle cascades

To improve the aerodynamic performance of steam turbine nozzle cascades, it is significant to study the effect of swept blades to control the flow field within the cascade. Numerical simulations of three different sweep angle blades (−20°, +20° and 0°) were carried out, using CFD modelling. Simulation results showed that the aft-swept blade can effectively improve the corresponding flow characteristics and reduce the total pressure loss. Meanwhile, it has better aerodynamic performance than the straight blade and the fore-swept blade

Research on Effects of Incidence to Turbine Guide Cascade Aerodynamic Performance

When steam turbine set runs, the changes of incidence angle could cause the change of the flow loss in the cascade passages. It was necessary to research the flow performance in steam turbine passages by changing incidence angle. With the help of hydrodynamic software CFX, we could conduct numerical simulations at three incidence angles of 20°, 0°, and -20°, respectively. The computation results indicated that the blades with aft-loading profile had a good adaptation to the incidence angle. After changing incidence angle, the incidence angle affected the distribution of static surface pressure less within most of the scope of pressure surface and suction surface than other location. However, incidence angle −20° would decrease pressure loss within a narrow range, and incidence angle 20° would increase pressure loss

Automatic spin-chain learning to explore the quantum speed limit

One of the ambitious goals of artificial intelligence is to build a machine that outperforms human intelligence, even if limited knowledge and data are provided. Reinforcement Learning (RL) provides one such possibility to reach this goal. In this work, we consider a specific task from quantum physics, i.e. quantum state transfer in a one-dimensional spin chain. The mission for the machine is to find transfer schemes with fastest speeds while maintaining high transfer fidelities. The first scenario we consider is when the Hamiltonian is time-independent. We update the coupling strength by minimizing a loss function dependent on both the fidelity and the speed. Compared with a scheme proven to be at the quantum speed limit for the perfect state transfer, the scheme provided by RL is faster while maintaining the infidelity below $5\times 10^{-4}$. In the second scenario where a time-dependent external field is introduced, we convert the state transfer process into a Markov decision process that can be understood by the machine. We solve it with the deep Q-learning algorithm. After training, the machine successfully finds transfer schemes with high fidelities and speeds, which are faster than previously known ones. These results show that Reinforcement Learning can be a powerful tool for quantum control problems.Comment: 13 pages, 9 figure

Optical absorption of angulon in metal halide perovskites

We theoretically study the optical absorption of an angulon in the metal halide perovskites (MHP) based on the improved Devreese-Huybrechts-Lemmens model, where the formation of quasiparticle angulon states originates from the organic cation rotating in the inorganic octahedral cage of MHP. We find that the resonance optical absorption peaks are appeared when the energy of incident photon matches the quantum levels of angulon. Moreover, the intensity of absorption depends on the quantum states of phonon angular momentum. These theoretical results provide significant insight to study the redistribution of angular momenta for the rotational molecules immersed into the many-body environment.Comment: 10 pages, 2 figures, submitted to Phys. Rev. A (Welcome to comments

Evaluation and Improvement of Pumping Well Operating Conditions in an Oil Field Block Based on Grey Correlation Analysis

The "Oil and Gas Water Well Production Data Management System Database" provides great assistance for oilfield production, monitoring, and management. However, due to the harsh conditions of oil field wells and the lack of some test data, traditional management methods are no longer suitable for present condition. At the same time, optimization analysis for a single oil well has a high cost and low efficiency, and it is difficult to achieve the modern management goal of large-scale pumping well groups. In this paper, the grey correlation method is used to analyze the direct correlation between the influencing factors and the system efficiency, surface equipment driving efficiency, and wellbore lifting efficiency, and the improvement method against factors with strong correlation is prioritized. A multi-node evaluation index system for pumping well systems and corresponding improvement methods were constructed, and evaluation software was compiled. This technology considers the running condition of the pumping unit in one oil field block, and selects the oil wells to be improved according to the evaluation index, and puts forward the targeted improvement methods according to the common problems of the oil well. This paper provides a set of reliable technical methods for the efficient management of the oil well in the oil field block

Effect of Core Competence and Brand Personality of Short Video Websites on User Loyalty

Influenced by the strong demand for fragmented entertainment from network users, the short video industry has entered an unprecedented period of rapid development, but any emerging industry goes through a life cycle. The purpose of this article is to explore the impact of core competitiveness and brand personality on user loyalty in short video industry by using questionnaire survey for Chinese short video users and statistical analysis based on survey data, so as to provide suggestions for short video websites to improve user loyalty and prolong life cycle. Core competitiveness and brand personality are considered as independent variables, user perceived value characteristics as the moderator variable, and user loyalty as the dependent variable to construct the research model. The SPSS and AMOS statistical analysis tools are applied to reliability analysis, validity analysis, and structural equation model analysis of the survey data. The Results show that the core competitiveness of the short video industry has no positive effect on user perceived value; and the brand personality has a significant positive impact on the user perceived value; the core competitiveness of the short video industry has a significant positive impact on the user loyalty; the brand personality has a significant positive impact on the user loyalty; and the user perceived value has a significant positive impact on the user loyalty. Based on the above results, we suggest the short video website improve its core competitiveness through creating original videos, and adopting diversified content production modes, using network transmission and mass media to promote short video products, so as to strengthen the brand communication, shape the brand image and enhance the user perceived value, etc

Review of variable speed drive technology in beam pumping units for energy-saving

Beam pumping units have been widely used in oilfields worldwide due to its simple structure, strong field adaptability, and convenient maintenance. Different energy-saving technologies have also been broadly applied in various beam pumping units. Among these energy-saving methods, the variable speed drive is one of the most acceptable techniques in the oil and gas industry. In this paper, the energy-saving technology of variable speed drives is discussed in detail for beam pumping units pointing out existing difficulties and current research status in kinematics. Three application examples of a variable speed drive in Daqing oilfield, the largest oilfield in China, is shown

Mobile defects as mediated states for charge-carrier trapping in metal halide perovskites quantum dots

The migration motion of defects in metal halide perovskites quantum dots (MHPQDs) results in charge-carrier trapping become more complicated. We study two-step trapping mediated by mobile defects between the ground state of MHPQDs and a fixed-depth defect using a full-configuration defect method, where all possible trapping processes mediated by these mobile defects could be reproduced and the fastest channels among them are picked out. We find that these two-step trapping processes could keep more one order of magnitude faster than these direct ones as mobile defect with the appropriate localization strength, which implies that these indirect trapping should play the crucial rule to determine the non-radiative recombination losses. These results provide the significant explanation for studying non-radiation processes of carriers in the presence of the migration defects in recent experiments. Moreover, this model will be available to analyze some key performance related defects in electronic devices.Comment: 5 pages, 3 figure