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Abstract In this paper, an open‐circuit fault‐tolerant topology of LC‐coupling hybrid active power filter (LC‐HAPF) and its control strategy are proposed at the switch level, which can greatly improve the reliability of the system. The proposed structure has a contactor between the midpoint of each bridge arm and the negative bus of the dc‐link capacitor. When a single‐phase fault occurs, the proposed LC‐HAPF can be reconstructed into a three‐phase four‐switch system to compensate for the harmonic and reactive power, while the power quality compensation effect is hardly affected. When a two‐phase fault occurs, the operation of the normal bridge arm is not affected, and the two faulty bridge arms can suppress harmonic current and compensate for a fixed reactive power through the passive filters. When the bridge arms all fail, the whole device acts as a passive filter to suppress the harmonic current of the load and to compensate for reactive power as well. Finally, the effectiveness of the proposed topology and its control strategy is verified by simulation and experiment results.

Objective To observe the effect of Baduanjin exercise on postoperative cardiac rehabilitation of patients with percutaneous coronary intervention (PCI)for acute coronary syndrome(ACS). Methods From January to December 2021, 96 ACS patients after PCI were randomly divided into the intervention group and the control group, with 48 cases in each group. Patients in the control group received routine care, and patients in the intervention group implemented the Baduanjin exercise on the basis of routine care. Cardiac function and psychological indicators were collected before discharge and 12 weeks after the intervention. Results Forty-six patients in the observation group and 47 patients in the control group were recruited for the further analysis. After the intervention, distance of 6-min Walking Test (6MWT) and left ventricular ejection fraction (LVEF) in the observation group were higher than those in the control group, and the left ventricular end-diastolic inner diameter (LVEDD) and blood N-terminal brain natriuretic peptide precursor (NT-porBNP) were lower than those in the control group (P＜0. 05). The generalized anxiety disorder (GAD-7) scores and the patient's health questionnaire (PHQ-9) scores in both groups decreased compared with those before the intervention, and the GAD-7 scores and PHQ-9 scores in the intervention group decreased more significantly than those in the control group (P＜0. 05). Conclusion Baduanjin exercise is effective to improve the cardiac function, anxiety and depression of ACS patients after PCI. (目的 观察八段锦运动在急性冠脉综合征(ACS)患者经皮冠状动脉介入治疗(PCI)术后心脏康复中的应用效果。方法 选取2021年1月—12月医院心内科收治的ACS行PCI治疗的患者96例, 随机分为干预组和对照组, 各48例。对照组患者接受常规护理, 干预组患者在常规护理的基础上实施八段锦运动。出院前、干预12周后分别收集两组患者的心功能指标和心理学指标。结果 干预组1例失访, 1例自愿退出研究, 最终纳入46例; 对照组有1例自愿退出研究, 最终纳入47例。干预后, 干预组患者6分钟步行试验(6MWT)、左心室射血分数(LVEF)较对照组升高, 左心室舒张末期内径(LVEDD)、血N末端脑钠肽前体(NT-porBNP)较对照组降低, 差异有统计学意义(P＜0. 05)。两组患者的广泛性焦虑障碍(GAD-7)评分以及患者健康问卷(PHQ-9)评分较干预前均有所下降, 干预组患者的GAD-7评分、PHQ-9评分较对照组下降明显, 差异有统计学意义(P＜0. 05)。结论 针对ACS行PCI的患者开展八段锦运动, 能有效改善患者心功能以及焦虑、抑郁情绪, 促进患者“双心”健康。)

Block collapse or sliding is one of the main failure modes of rock slope engineering. Namely, block stability analysis plays a key role in rock slope engineering. Taking the Shenxianju rock slope in Xianju County, Zhejiang Province as the research background, this paper mainly conducts the stability analysis and visualization of rock blocks. A new method for fitting structural planes and free faces is proposed based on the linear regression method and the non-uniform rational B-spline method. Then, based on the coordinate projection method, the method for calculating the stability coefficients of the single sliding surface and double sliding surface blocks is proposed. Finally, the unmanned aerial vehicle (UAV) measurement technology combined with the coordinate projection method is used to develop a CPG program using MATLAB, which can be adopted in the stability analysis of planar polyhedron blocks and curved blocks in rock slope engineering. This program enables the spatial representation and visualization of structural planes, free faces and unstable blocks. Engineering practice shows that the new proposed method is effectively applicable to engineering geological disasters, such as rockfall and collapse. The results of the program calculation are basically consistent with those of the coordinate projection block theory, demonstrating that this method is reliable and the developed CPG program is feasible. This method is of vital significance in practical engineering since it can greatly improve the efficiency of block stability analysis.

This paper proposes a nonlinear electromagnetic-thermal-velocity coupling model to study the insulation performance of converter transformer, in which the saddle-like electric-stress dependence is considered under compound alternating current-direct current (AC-DC) voltage situation. Firstly, the conductance of transformer oil and oil-immersed pressboard have been measured through constructed three-electrode experimental system. An interesting electric-stress characteristic, which is saddle-like electric-stress dependence is obtained and counted in the thermal-insulation analysis in the proposed model. Then, the high-order harmonics of compound AC-DC voltage have been considered in the built electromagnetic-thermal-velocity coupling model. Additionally, the impact of non-uniform temperature result has been mapped to the electric field domain through interpolation method, due to different meshes between the flow-thermal and electric fields in accordance with distinct computational characteristics. Finally, the performance of nonlinear thermal-electric coupling properties, including saddle-like electric-stress dependence, have been considered in the proposed coupling model. Results determine that saddle-like thermal-electric dependent properties would considerably change insulation capability, compared with results from the traditional method. Even intensity field of some sampling points could jump more than 1.6 kV/mm. Therefore, it is essential to evaluate the insulation design by practical saddle-like electric-dependent properties.

This paper presents an ultra-wideband metal-mountable antenna used in the ultra-highfrequency (UHF) partial discharge (PD) detection. The designed antenna combines a coplanar waveguide antenna and multilayer substrates to effectively broaden its bandwidth when mounted on a conductive surface. These substrates consist of two layers of FR-4 dielectric substrates and two layers of the absorbing gasket, which is adapted to absorb the reflected electromagnetic signals. The parametric study is conducted to optimize antenna performance. A prototype is fabricated to confirm the design, and the measurement results show good agreement with the simulation. When mounted on the metal plate, the proposed antenna covers the UHF bandwidth of 400 MHz-3 GHz for S11

Multi-break vacuum circuit breakers (VCBs) are the most potential approach for applying VCBs to high voltage power system. However, it has higher thermal stability requirements than normal single break VCBs due to its complex structure and high rated current. In this paper, a novel 363 kV/5000 A/63 kA SF6 gas insulate (GI) VCB with series and parallel structure is proposed. To analyze its temperature rise, a 3D coupled electromagnetic-thermal-fluid model is established based on actual size and calculated by finite element method under rated condition, which enables prediction of the temperature distribution of the contacts of VCB and bus bar. In the numerical model, the vacuum chamber is modelled as solid material with temperature dependent effective thermal conductivity while skin effect, nonlinear property of conductor resistivity and turbulence model are taken into consideration. The simulation results show that the hot spot is the contacts of VCB with a temperature of 102.2 K, while the temperature of busbars reach at 92.3 K. In addition, the influences of contact resistance, short circuit current on the temperature rise are discussed. Finally, the simulation results are validated by temperature rise experiment on prototype. Using the proposed model, the temperature rise and hot spot area can be predicted in advance, which could finally facilitate the design and performance evaluation of the 363 kV GI-VCB.

In this paper，a new formula of popularity was proposed. It included the term deficit bandwidth and was based on the new popularity. Those streaming media files which need to be replicated were determined. A concept named comprehensive performance indicators was proposed. Peers were sorted by their comprehensive performance indicators and those peers with high comprehensive performance indicators had priority to place these popular files. Replacement algorithm would be carried out if there was no enough space to cache the new file, and the file which had largest ratio of its duplicates to the desired duplicates would be replaced by the new file. Experimental results show that the workload of the proposed algorithm, compared with proportional replication algorithm, is in steady conditions earlier about 13% in advance and is smaller. Its workload in steady-state condition is about 33.3% of the workload of the proportional replication algorithm. Meanwhile, more of one in a thousand peers has the desired requested rates in steady-state. Besides, the proposed algorithm has more stationary transient process.

In this paper, the effects of temperature and atmosphere on the gasification reaction of ferro-coke were investigated in consideration of the actual blast furnace conditions. Besides, the microstructure of the cokes was observed by scanning electron microscope (SEM). It is found that the weight loss of ferro-coke during the gasification reaction is significantly enhanced in the case of increasing either the reaction temperature or the CO2 concentration. Furthermore, compared with the normal type of metallurgical coke, ferro-coke exhibits a higher weight loss when they are gasified at the same temperature or under the same atmosphere. As to the microstructure, inside the reacted ferro-coke are a large amount of pores. Contrary to the normal coke, the proportions of the large-size pores and the through holes are greatly increased after gasification, giving rise to thinner pore walls and hence a degradation in coke strength after reaction (CSR).

We present a quantitative analysis of phosphorus (P) flows that characterize the food production-consumption system metabolism in a low-income, food, and phosphorus deficient country, using Comoros, a small African island state, as an example from the year 2000 to 2011. The data were interpreted in terms of the connections between crop production, livestock breeding, human consumption, and soil stock, using the substance flow analysis (SFA) model. We found that the total P input into Comoros totaled 132.37 t in 2000 and 270.60 t in 2011, whereas the total P output totaled 567.40 t in 2000 and 702.29 t in 2011. Farmers in Comoros are cropping with little or no P input, resulting in a soil P deficiency; it varied from 435.03 t in 2000 to 431.69 t in 2011. In addition, the Phosphorus Use Efficiencies (PUEs) of plant and animal production in Comoros were 131.80% and 14%, respectively, in 2011. This is the first SFA of a small island state, and the lack of a closed P loop is a major issue for the country in terms of P security and this has not changed between 2000 and 2011. This study proposes crucial solutions for improving the PUE through recycling and reusing animal manure, human excreta, and household solid organic waste.

High capacity polymer dielectrics that operate with high efficiencies under harsh electrification conditions are essential components for advanced electronics and power systems. It is, however, fundamentally challenging to design polymer dielectrics that can reliably withstand demanding temperatures and electric fields, which necessitate the balance of key electronic, electrical and thermal parameters. Herein, we demonstrate that polysulfates, synthesized by sulfur(VI) fluoride exchange (SuFEx) catalysis, another near-perfect click chemistry reaction, serve as high-performing dielectric polymers that overcome such bottlenecks. Free-standing polysulfate thin films from convenient solution processes exhibit superior insulating properties and dielectric stability at elevated temperatures, which are further enhanced when ultrathin (~5 nm) oxide coatings are deposited by atomic layer deposition. The corresponding electrostatic film capacitors display high breakdown strength (>700 MV m-1) and discharged energy density of 8.64 J cm-3 at 150 °C, outperforming state-of-the-art free-standing capacitor films based on commercial and synthetic dielectric polymers and nanocomposites.

To explore senior high school students' subjective socioeconomic status influence on their subjective well-being, and the role of self-esteem and peer relationships in it, a questionnaire survey was conducted among 394 high school students from the first grade to the third grade in Beijing using the Adolescent Subjective Socioeconomic Status Scale, Self-Esteem Scale, Adolescent Peer Relationship Scale, and Subjective Well-being Scale. The results show that: (1) Subjective socioeconomic status can positively predict subjective well-being; (2) Self-esteem and peer relationship play a completely mediating role in the relationship between subjective socioeconomic status and subjective well-being. Therefore, the improvement of high school students' subjective well-being can be achieved through the dual path of intervening in students' self-esteem level and improving their peer relationships.

Sulfur(VI) fluoride exchange (SuFEx) is a category of click chemistry that enables covalent linking of modular units through sulfur(VI) connective hubs. The efficiency of SuFEx and the stability of the resulting bonds have led to polymer chemistry applications. Now, we report the SuFEx click chemistry synthesis of several structurally diverse SOF4-derived copolymers based on the polymerization of bis(iminosulfur oxydifluorides) and bis(aryl silyl ethers). This polymer class presents two key characteristics. First, the [-N=S(=O)F-O-] polymer backbone linkages are themselves SuFExable and undergo precise SuFEx-based post-modification with phenols or amines to yield branched functional polymers. Second, studies of individual polymer chains of several of these new materials indicate helical polymer structures. The robust nature of SuFEx click chemistry offers the potential for post-polymerization modification, enabling the synthesis of materials with control over composition and conformation.