大型高炉布料参数对煤气流的影响

高炉装料制度与炉况参数之间存在着内在的紧密联系,高炉布料仿真模型是装料制度与炉况参数的纽带.本文利用高炉布料仿真模型计算出区域焦炭负荷指数和炉料落点,并与煤气流参数K值、热负荷、炉喉钢砖温度建立了回归方程.研究了平台+漏斗和中心加焦两种布料模式下布料参数调整方式与煤气流参数的关系,得出了大型高炉煤气流控制方面的操作要点.     

Development of a high-speed current limiter for a 6 kV distribution system and evaluation of its effectiveness

We have developed a high-speed fault current limiting equipment for a 6 kV distribution system. The main components of this equipment are a high-speed vacuum switch (VCB) and gate turn-off thyristors (GTO) connected in parallel, and a current limiting impedance with low linear resistance in parallel with the switch. The usual load current is carried by the VCB. In case of a power system fault, the fault current is commutated to and interrupted by the GTO on opening the VCB. Tests confirm that the equipment can interrupt an estimated short-circuit current of 13 kA_rms by limiting to less than 3.5 kAp. The interrupt time was less than 2 ms. This response is about 100 times faster than that of conventional mechanical circuit breakers. The fast interruption current limiter can protect distribution systems within a few ms of a severe short circuit fault occurrence. The primary operational benefit of this equipment is the reduction of instantaneous voltage drop at the bus or on sound lines and of current stress on power system equipment during a power failure. © 1998 Technica, Electr Eng Jpn, 125(3): 11–21, 1998     

基于参数辨识的永磁同步电机无位置传感器控制

针对电机运行过程中参数变化会影响永磁同步电机(PMSM)无位置传感器控制性能的问题,将递推的最小二乘法(RLS)用于PMSM参数的在线辨识,在最大转矩电流比控制策略下,使用基于BP神经网络改进的模型参考自适应系统构建无位置传感器控制方案,提出了基于在线参数辨识的PMSM无位置传感器控制方案。运用递推的RLS对PMSM的交轴电感和转子磁链进行在线辨识,并将参数辨识结果应用于电机无位置传感器算法中。仿真和试验证明了基于递推的RLS参数辨识算法可以对PMSM的转子磁链和交轴电感值进行准确辨识,基于参数辨识的PMSM无位置传感器控制方案性能更好。     

Sets of Frequency Hopping Sequences: Bounds and Optimal Constructions

Frequency hopping spread spectrum and direct sequence spread spectrum are two main spread coding technologies in communication systems. Frequency hopping sequences are needed in frequency hopping code-division multiple-access (FH-CDMA) systems. In this paper, four algebraic and a combinatorial constructions of optimal sets of frequency hopping sequences with new parameters are presented, and a number of bounds on sets of frequency hopping sequences are described.     

Solar cells based on carbon thin films

Carbon as an alternative material for low-cost and high-efficiency solar cell is attempted. Thin films of semiconducting n- (p-doped) and p- (un-doped) type carbon have been deposited on various substrates by ion beam sputtering and pyrolysis, using camphor as a natural carbon precursor. The optical gap of carbon has been found to be around 1.05 and <0.5 eV for n- and p- type films, respectively. Studies dealing with the temperature dependence of conductivity reveal semiconducting behavior of both the films and Hall measurements indicate n-type conduction of p-doped ion beam sputtered films and p-type conduction of un-doped pyrolysed films. Photovoltaic solar cells of configurations n-C/p-Si and n-C/p-C/p-Si have been fabricated and their photoresponse characteristics under AM 0 and 1 SUN illumination conditions have been studied. An enhanced efficiency of 1.52% has been obtained for the n-C/p-C/p-Si solar cell with the insertion of a p-C layer.     

Improvement of the MOCVD-grown InGaP-on-Si towards high-efficiency solar cell application

The thermal cycle annealing (TCA) for GaAs layer grown on Si substrate (GaAs/Si) increased the photoluminescence (PL) intensity of InGaP epilayer which was regrown on the GaAs/Si substrate by about 100 times. The full-width at half-maximum (FWHM) of double-crystal X-ray diffraction (DXRD) was decreased from 313 to 251 arcsec. From the electron-beam-induced current (EBIC) image measurements, the defect-related dark spots density (DSD) of the regrown InGaP layer was reduced by about 30% by using TCA GaAs/Si substrate. This means that TCA treatment for GaAs layer effectively increased the crystal quality of InGaP epilayer regrown on GaAs/Si substrate (InGaP/GaAs/Si). The PL intensity of InGaP epilayer was also enhanced due to the passivation of the residual defect-related nonradiative recombination centres by post-growth phosphine (PH₃/H₂=10%) plasma exposure.     

Intrinsic ferromagnetism in nanocrystalline Mn-doped ZnO depending on Mn concentration

The physical properties of Zn(1-x)Mn(x)O nanoparticles synthesized by thermal decomposition are extensively investigated by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman light scattering and Hysteresis measurements. XRD and XPS spectra reveal the absence of secondary phase in nanocrystalline ZnO doped with 5% or less Mn; and, later confirms that the valance state of Mn to be 2+ for all the samples. Raman spectra exhibit a peak at 660 cm(-1) which we attribute to the intrinsic lattice defects of ZnO with increasing Mn concentration. Overall, our results demonstrate that ferromagnetic properties can be realized while Mn-doped ZnO obtained in the nanocrystalline form.     

Effects of Active-Center Reduction of Plant-Type Ferredoxin on Its Structure and Dynamics: Computational Analysis Using Molecular Dynamics Simulations

“Plant-type” ferredoxins (Fds) in the thylakoid membranes of plants, algae, and cyanobacteria possess a single [2Fe-2S] cluster in active sites and mediate light-induced electron transfer from Photosystem I reaction centers to various Fd-dependent enzymes. Structural knowledge of plant-type Fds is relatively limited to static structures, and the detailed behavior of oxidized and reduced Fds has not been fully elucidated. It is important that the investigations of the effects of active-center reduction on the structures and dynamics for elucidating electron-transfer mechanisms. In this study, model systems of oxidized and reduced Fds were constructed from the high-resolution crystal structure of Chlamydomonas reinhardtii Fd1, and three 200 ns molecular dynamics simulations were performed for each system. The force field parameters of the oxidized and reduced active centers were independently obtained using quantum chemical calculations. There were no substantial differences in the global conformations of the oxidized and reduced forms. In contrast, active-center reduction affected the hydrogen-bond network and compactness of the surrounding residues, leading to the increased flexibility of the side chain of Phe61, which is essential for the interaction between Fd and the target protein. These computational results will provide insight into the electron-transfer mechanisms in the Fds.     

Development and Regeneration of Muscle,Tendon, and Myotendinous Junctions in Striated Skeletal Muscle

Owing to a rapid increase in aging population in recent years, the deterioration of motor function in older adults has become an important social problem, and several studies have aimed to investigate the mechanisms underlying muscle function decline. Furthermore, structural maintenance of the muscle–tendon–bone complexes in the muscle attachment sites is important for motor function, particularly for joints; however, the development and regeneration of these complexes have not been studied thoroughly and require further elucidation. Recent studies have provided insights into the roles of mesenchymal progenitors in the development and regeneration of muscles and myotendinous junctions. In particular, studies on muscles and myotendinous junctions have—through the use of the recently developed scRNA-seq—reported the presence of syncytia, thereby suggesting that fibroblasts may be transformed into myoblasts in a BMP-dependent manner. In addition, the high mobility group box 1—a DNA-binding protein found in nuclei—is reportedly involved in muscle regeneration. Furthermore, studies have identified several factors required for the formation of locomotor apparatuses, e.g., tenomodulin (Tnmd) and mohawk (Mkx), which are essential for tendon maturation.