[en] Transmission lines are important lifeline projects. The stable operation of transmission lines is closely related to economic and social security and stability. Ice storm seriously affects the safety of transmission lines. The simulation analysis of ice damage of transmission tower structure has important theoretical significance and engineering value. In this paper, the finite element software ANSYS is used to analyze the buckling of the self-supporting tower based on eigenvalue buckling analysis and nonlinear buckling analysis. The effects of vertical span, uniform ice coating, uneven ice coating, and wind load were considered. The ice thickness of the tower buckling is reduced with the vertical span decreasing under uniform ice coating the transmission line. As the coefficient of unevenness increases, the thickness of the unstable ice coating of the tower drops sharply. The unstable wind speed decreases with the increase of ice thickness. (paper)

[en] In this work, the optimal design method for self-supporting transmission tower is put forward, whose procedure is that the tower body form is selected intelligently firstly and then the members types of tower are chosen. The case base of towers is established with application of object-oriented technology. Then, the knowledge of tower body is mined out with case based reasoning and data mining technology. At the same time, the structural regulations of tower in the standard are merged into the knowledge base. So, the intelligent selection system of tower structural scheme based on case reasoning and data mining is explored. A 500kV self-supporting tower is optimized according to above method and a real model test is conducted. Comparison between optimal tower and original tower indicates that weight of optimal tower is decreased by 3% and its ultimate bearing capacity is increased by 19%. Statistical analysis results of 20 optimal towers indicates that the weight is average reduced by 4.7%, the components of the optimal tower are stressed more uniformly and bearing capacity of the tower is enhanced 12% at least. (paper)

[en] A series of willemite based ceramics Zn₂Ge_1+xO_4+2x with − 0.1 ≤ x ≤ 0.2 were prepared by the solid-state reaction method. Influences of Ge nonstoichiometry on the crystal structure, densification, and microwave dielectric properties were evaluated in terms of X-ray diffraction, SEM, dielectric measurements and far-infrared spectra. Ge excess favored the formation of single-phase willemite but a high level of excess induced appearance of GeO₂. In contrast, nominal composition and those with Ge deficiency comprised of ZnO and the willemite phase. Ge excess was found to be beneficial to the densification and dielectric properties optimization of Zn₂Ge_1+xO_4+2x. A composition with x = 0.1 (Zn₂Ge_1.1O_4.2) exhibited the optimum microwave dielectric properties with a relative permittivity ε_r ~ 7.09, a quality factor Q × f ~ 112,700 GHz (at 14.48 GHz), and a temperature coefficient of resonance frequency τ_f ~ − 51 ppm/°C.

[en] Carbon nanotube (CNT) is one of the most widely used nanomaterials recently. Since it was discovered by Iijima in 1991, its various synthesis methods were being mature in the past 30 years. The research of carbon nanotube applications in different fields has never stopped. Since a number of researchers have tested the excellent properties of CNTs, it provides an optimistic expectation about CNT applications in the future. This review summarizes the historical development of CNTs, and briefly introduces three main CNT synthesis methods and their properties. (paper)

[en] AgSbTe${}_2$ exhibits superior thermoelectric performance in the mid-temperature region, but its electrical properties are strongly affected by intrinsic defects and secondary phases. Distinctively, the high mobility electrons still play an important role as minority carriers in p-type AgSbTe${}_2$ even below the bipolarization temperature and decrease the Seebeck coefficient. Here, the Al and Se dual alloying can effectively increase the hole concentration by reducing the cation vacancy formation energy and simultaneously reduce the electron concentration by suppressing the n-type Ag${}_2$Te secondary phase are demonstrated, which results in the shift of carrier transport from two-type to one-type as confirmed by Hall measurement. Consequently, through adjusting the ratio of hole and electron conductivity, the average power factor of alloyed sample is enhanced by 70%. Combined with further reduced lattice thermal conductivity resulting from high-density stacking faults and superstructures, a maximum zT of 1.90 and an average zT of 1.42 are obtained in the temperature range of 323 to 623 K in the (AgSbTe${}_2$)${}_{0.98}$(AgAlSe${}_2$)${}_{0.02}$ sample. Finally, based on the finite element analysis modeling results, both single-leg and double-leg thermoelectric devices are fabricated, which show high conversion efficiency of 11.2% and 5.2%, respectively. (© 2024 Wiley‐VCH GmbH)

[en] Nanospheres, nanocones, and nanowires are three typical polypyrrole (PPy) nanoarchitectures and electrochemically polymerized with the dope of chondroitin sulphate (CS) in this study. CS, a functional biomacromolecule, guides the formation of PPy nanoarchitectures as the dopant and morphology-directing agent. Combined with our previous reported other PPy nanoarchitectures (such as nanotube arrays and nanowires), this work further proposed the novel mechanism of the construction of PPy/CS nanoarchitectures with the synergistic effect of CS molecular chains structure and the steric hindrance. Compared to the undoped PPy, MC3T3-E1 cells with PPy/CS nanoarchitectures possessed stronger proliferation and osteogenic differentiation capability. This suggests that PPy/CS nanoarchitectures have appropriate biocompatibility. Altogether, the nanoarchitectured PPy/CS may find application in the regeneration of bone defect. - Highlights: • The formation mechanism of PPy nanoarchitectures was proposed. • CS acted as biofunctional dopant and morphology-directing agent in PPy forming. • PPy-CS nanoarchitectures were dependent on the Py/CS ratio

[en] Highlights: • α-SrV₂O₆ and β-SrV2O₆ phase were coexisted below 500 °C, and stable α-SrV₂O₆ phase at 630 °C. • Optimum microwave dielectric properties: ε_r ∼9.66, Q × f ∼23,200 GHz, and τ_f ∼ −205 ppm/°C were obtained. • CaTiO₃ successfully adjusted τ_f value toward to near-zero with −2.7 ppm/°C. • Their chemical compatibility with the aluminum electrodes were evaluated. - Abstract: A novel ultralow-firing microwave dielectric ceramic SrV₂O₆ was prepared at 630 °C through the solid-state method. Phase evolution and crystal structure were analyzed by XRD and Raman spectroscopy. Results show that α-SrV₂O₆ and β-SrV₂O₆ phase coexisted when fired at lower temperatures (α-SrV₂O₆ phase was obtained at 550 °C and remained stable up to 660 °C. Optimum microwave dielectric properties with a quality factor ∼23,200 GHz, a low dielectric constant ∼9.66, and a temperature coefficient of resonant frequency ∼−205 ppm/°C was obtained. SrV₂O₆ ceramic possessed chemical compatibility with aluminum electrodes when cofired at 630 °C. The temperature stability of SrV₂O₆ was adjusted by forming composite ceramics with CaTiO₃ and a near-zero τ_f ∼−2.7 ppm/°C was achieved in the 0.75SrV₂O₆-0.25CaTiO₃ ceramic. All the results show that the SrV₂O₆ ceramic might be a promising candidate as substrates in ultra-low temperature cofired (ULTCC) ceramics.

[en] Highlights: • Several dielectric materials in the Li₂WO₆ (Ln = La, Nd, Sm, Eu, Gd) were prepared. • Effects of rare-earth elements at Ln-site on the phase purity, crystal structure were analyzed. • The microwave dielectric properties of Ln₂WO₆ were reported for the first time.