A Statistical Model of <Emphasis Type="Italic">I</Emphasis><Subscript><Emphasis Type="Italic">c</Emphasis></Subscript> Changes for Bending Bi-2223 Tapes

Bi-2223 tape was one of the high-temperature superconductors with commercial applications. One of the applications was bending and winding Bi-2223 tape into solenoids to produce high magnetic fields. To study bending properties, three multifilamentary of Bi-2223 tapes sheathed with silver alloys were manufactured. Bending experiments for the tapes were performed, and critical currents I _c of tapes with definite bending radius were measured. And, current transferring mechanisms in filaments were analyzed, as well. Experimental results showed that silver alloy sheathed tapes had better bending properties than pure silver-sheathed one. On the contrary, to describe bending radius dependence of I _c , a statistical model was suggested. The model expected that bending radius dependence of I _c was following an exponential law that was quantitatively expressed by mathematic expressions. Bending dependence of I _c could be calculated from the expression and calculated results agreed with experimental data very well. Therefore, the suggested model has successfully explained the experimental results.     

Synthesis of the Bi-2222 Compounds of Bi–Sr–Ln(Zr)–Cu–O (Ln = Sm,Eu, Gd,and Dy)

Bi-based superconducting compounds with the 2222 structure has been already synthesized in the Bi₂Sr₂- (Ln_1−x Ce _x )₂Cu₂O_10+y (Ln = Sm, Eu, and Gd) systems. One of the characteristics of these compounds is the existence of the fluorite-like (Ln_1−x Ce _x )₂O₂ block between two CuO₅ pyramids in the crystal structure. The tetravalent ions of Ce⁴⁺ are reported to be necessary to stabilize the 2222 structure. Recently, we have discovered that the Bi-2222 phase could be composed in the Bi₂Sr₂(Ln_2−x Zr _x )Cu₂O _z (Ln = Sm, Eu, Gd, and Dy) systems, where Zr⁴⁺ is used as a new tetravalent ion stabilizing the 2222 structure in stead of Ce⁴⁺. In the new system, nearly single 2222 phase samples have been obtained at the nominal composition of x=0.5 (Ln = Sm, Eu, and Gd) and in the range of 0.1≤x≤0.3 (Ln = Dy). Among them, the sample with Ln = Gd has the smallest resistivity at 273 K. But it is a semiconductor, and the conduction process at low temperatures is assumed to be followed by a two-dimensional VRH. The experimental results for the Gd samples with a partial substitution of Pb for Bi in the Bi₂Sr₂(Gd_2−x Zr _x )Cu₂O _z system are also reported.     

Effects of growth conditions on the domain structure and dielectric properties of (1 − x)Pb(Sc1/2Nb1/2)O3–xPbTiO3 single crystals

The studies of the (1 − x)Pb(Sc_1/2Nb_1/2)O₃–xPbTiO₃ (PSN–PT) single crystals reveal that the chemical and physical properties of the materials are affected by the growth conditions. By the measurements of the dielectric constant as a function of temperature upon cooling, it is found that crystals grown from the same charged stoichiometric composition (x = 0.425), but under different flux environments (i.e. the composition of flux and the flux to PSN–PT ratios are varied), show anomalies (i.e. phase transitions) at different temperatures. This phenomenon is attributed to the complex local chemical structure of the PSN–PT solid solution single crystals with B-site random occupancy of three different cations (Sc³⁺, Nb⁵⁺ and Ti⁴⁺). The dielectric and domain structure of the PSN–PT crystals with composition near the morphotropic phase boundary (MPB) are investigated, showing much more complex situations compared with Pb(Sc_1/2Nb_1/2)O₃.     

Wearable Textile‐Based Co−Zn Alkaline Microbattery with High Energy Density and Excellent Reliability

Wearable in‐plane Zn‐based microbatteries are considered as promising micropower sources for wearable electronics due to their high capacity, low cost, high safety, and easy integration. However, their applications are severely impeded by inadequate energy density arising from unsatisfactory capacity of cathode and poor cycling stability caused by degradation of electrode materials and Zn dendrite. Additionally, the short‐circuit induced safety issue caused by Zn dendrite is still a roadblock for Zn‐based microbatteries. Herein, a textile‐based Co?Zn microbattery with ultrahigh energy density and excellent cycling stability is demonstrated. Benefiting from the fast electron transport of three‐dimensional (3D) porous Ni‐coated textile and synergistic effect from the hierarchical Co(OH)₂@NiCo layered double hydroxide (LDH) core?shell electrode, the fabricated Co?Zn microbattery with high flexibility delivers superior energy/power densities of 0.17 mWh cm^?2/14.4 mW cm^?2, outperforming most reported micro energy storage devices. Besides, the trench‐type configuration as well as the 3D porous Zn@carbon clothes can avoid the short‐circuit‐induced safety issues, resulting in excellent cycling stability (71% after 800 cycles). The unique core?shell structure and novel configuration provide a brand‐new design strategy for high‐performance wearable in‐plane microdevices.     

Systematic Study of Alkali Cations Intercalated Titanium Dioxide Effect on Sodium and Lithium Storage

The fast development of electrochemical energy storage devices necessitates rational design of the high‐performance electrode materials and systematic and deep understanding of the intrinsic energy storage processes. Herein, the preintercalation general strategy of alkali ions (A = Li⁺, Na⁺, K⁺) into titanium dioxide (A‐TO, LTO, NTO, KTO) is proposed to improve the structural stability of anode materials for sodium and lithium storage. The different optimization effects of preintercalated alkali ions on electrochemical properties are studied systematically. Impressively, the three electrode materials manifest totally different capacities and capacity retention. The efficiency of the energy storage process is affected not only by the distinctive structure but also by the suitable interlayer spacing of Ti‐O, as well as by the interaction effect between the host Ti‐O layer and alien cations with proper size, demonstrating the pivotal role of the sodium ions. The greatly enhanced electrochemical performance confirms the importance of rational engineering and synthesis of advanced electrode materials with the preintercalation of proper alkali cations.     

Phase‐Controlled Synthesis of Monolayer W1−xRexS2 Alloy with Improved Photoresponse Performance

Tuning bandgap and phases in the ternary 2D transition metal dichalcogenides (TMDs) alloys has opened up unexpected opportunities to engineer optoelectronic properties and explore potential applications. In this work, a salt‐assisted chemical deposition vapor (CVD) growth strategy is reported for the creation of high‐quality monolayer W_1?xRe_xS₂ alloys to fulfill a readily phase control from 1H to DT by changing the ratio of Re and W precursors. The structures and chemical compositions of doping alloys are confirmed by combining atomic resolution scanning transmission electron microscopy‐annular dark field imaging with energy dispersive X‐ray spectroscopy (EDS) and X‐ray photoelectron spectroscopy, matching well with the calculated results. The field‐effect transistors (FETs) devices fabricated based on 1H‐W_0.9Re_0.1S₂ monolayer exhibit a n‐type semiconducting behavior with the mobility of 0.4 cm² V^?1 s^?1. More importantly, the FETs show high‐performance responsivity with a value of 17 µA W^?1 in air, which is superior to that of monolayer CVD‐grown WS₂. This work paves the way toward synthesizing monolayer ternary alloys with controlled phases for potential optoelectronic applications.     

Doping and electrical characteristics of in-situ heavily B-doped Si1−x−yGexCy films epitaxially grown using ultraclean LPCVD

Doping and electrical characteristics of in-situ heavily B-doped Si_1−x−yGe_xC_y (0.22<x<0.6, 0<y<0.02) films epitaxially grown on Si(100) were investigated. The epitaxial growth was carried out at 550°C in a SiH₄–GeH₄–CH₃SiH₃–B₂H₆–H₂ gas mixture using an ultraclean hot-wall low-pressure chemical vapor deposition (LPCVD) system. It was found that the deposition rate increased with increasing GeH₄ partial pressure, and only at high GeH₄ partial pressure did it decrease with increasing B₂H₆ as well as CH₃SiH₃ partial pressures. With the B₂H₆ addition, the Ge and C fractions scarcely changed and the B concentration (C_B) increased proportionally. The C fraction increased proportionally with increasing CH₃SiH₃ partial pressures. These results can be explained by the modified Langmuir-type adsorption and reaction scheme. In B-doped Si_1−x−yGe_xC_y with y=0.0054 or below, the carrier concentration was nearly equal to C_B up to approximately 2×10²⁰ cm⁻³ and was saturated at approximately 5×10²⁰ cm⁻³, regardless of the Ge fraction. The B-doped Si_1−x−yGe_xC_y with high Ge and C fractions contained some electrically inactive B even at the lower C_B region. Resistivity measurements show that the existence of C in the film enhances alloy scattering. The discrepancy between the observed lattice constant and the calculated value at the higher Ge and C fraction suggests that the B and C atoms exist at the interstitial site more preferentially.     

结合Bi-2DPCA与CNN的美式手语识别

针对现有美式手语（ASL）识别算法准确率低和模型训练时间长的问题,提出一种结合双向二维主成分分析（Bi-2DPCA）与卷积神经网络（CNN）并基于贝叶斯优化的识别算法。利用Bi-2DPCA算法对原始图像做数据降维处理,提取行、列方向的特征图,使用卷积神经网络对特征图进行训练分类,同时采用贝叶斯优化算法对模型超参数进行自动调参。在24分类ASL数据集上的实验结果表明,该算法的识别准确率达到99.15%,训练时间相比传统CNN算法减少90.3%。     

Thermally activated rotation of Co1−xO particles within zirconia grains

Yttria partially stabilized zirconia (Y-PSZ) and Co_1−xO powders in 4:1 molar ratio were sintered and then annealed at 1300 and 1600°C to investigate the orientation change of Co_1−xO particles within Y-PSZ grains. Transmission electron microscopic observations indicated the Co_1−xO particles remained nonepitaxy in Y-PSZ grains after annealing at 1300°C for 300 h. When fired at 1600°C for 1–100 h, submicro-sized Co_1−xO particles (denoted as C) reached parallel epitaxy relationship, i.e. [100]_C//[100]_Z, [010]_C//[010]_Z and another relationship, i.e. [111]_C//[100]_Z, //[011]_Z with respect to the host zirconia grain (denoted as Z) nearly free of tetragonal precipitates. On the other hand, larger intragranular Co_1−xO particles (>1 μm in diameter) failed to reach epitaxial orientations even subject to prolonged annealing (100 h) at 1600°C. The temperature and size dependence of orientation change of the intragranular particle is in accordance with theoretical consideration of Brownian type rotation of the particle above a critical temperature for anchorage release at interface.     

A new approach to secure economic power dispatch

This article presents a new nonlinear convex network flow programming model and algorithm for solving the on-line economic power dispatch with N and N−1 security. Based on the load flow equations, a new nonlinear convex network flow model for secure economic power dispatch is set up and then transformed into a quadratic programming model, in which the search direction in the space of the flow variables is to be solved. The concept of maximum basis in a network flow graph was introduced so that the constrained quadratic programming model was changed into an unconstrained quadratic programming model which was then solved by the reduced gradient method. The proposed model and its algorithm were examined numerically with an IEEE 30-bus test system on an ALPHA 400 Model 610 machine. Satisfactory results were obtained.