民国初期(1912～1937)广州城市建设理念初探

民国初期,广州曾经产生了一个建设小高潮,其间城市发展在达成良性循环的目标过程中,政府及城市管理者探索了在筹措资金、创造投资环境、以城养城等经营城市方面的有效途径。     

Fabrication and electrical properties of MoS2 nanodisc-based back-gated field effect transistors

Two-dimensional (2D) molybdenum disulfide (MoS₂) is an attractive alternative semiconductor material for next-generation low-power nanoelectronic applications, due to its special structure and large bandgap. Here, we report the fabrication of large-area MoS₂ nanodiscs and their incorporation into back-gated field effect transistors (FETs) whose electrical properties we characterize. The MoS₂ nanodiscs, fabricated via chemical vapor deposition (CVD), are homogeneous and continuous, and their thickness of around 5 nm is equal to a few layers of MoS₂. In addition, we find that the MoS₂ nanodisc-based back-gated field effect transistors with nickel electrodes achieve very high performance. The transistors exhibit an on/off current ratio of up to 1.9 × 10⁵, and a maximum transconductance of up to 27 μS (5.4 μS/μm). Moreover, their mobility is as high as 368 cm²/Vs. Furthermore, the transistors have good output characteristics and can be easily modulated by the back gate. The electrical properties of the MoS₂ nanodisc transistors are better than or comparable to those values extracted from single and multilayer MoS₂ FETs.     

Radio planning of energy-aware cellular networks

This paper introduces a joint planning and management optimization approach for cellular networks to limit energy consumption while guaranteeing QoS and minimizing operators Capex and Opex. The modeling framework shows that an effective energy-efficient operation depends on the planning decisions. Conversely, it also shows that planning with energy management operation in view yields more versatile topologies than more traditional models based only on Capex. Results for LTE networks are provided and show that savings up to 65% in energy expenses are possible with slight increases in capital investments.     

Optimisation of method for reducing residual stresses after cold bar drawing

Abstract

A new method to reduce the residual stresses after cold bar drawing has been proposed and optimised. This new method addresses the disadvantages of previous methods proposed by the authors, and needs neither the use of an extra finishing die nor an intricate die geometry. The application of axial tension to the bar or wire after drawing is all that is required, and by adjusting the magnitude of the tension it is possible to control the residual stresses in the final product. Axisymmetric elastic-plastic finite element analysis was carried out to examine quantitatively the influence of tension, followed by laboratory experiments using a thick, not thin, bar for convenience of measurement of residual stresses. The optimum value of tension was then determined. The applicability of the proposed method is discussed in the present paper. The new method is especially effective when applied to high speed cold drawing of an extremely thin wire, because the tension applied to the wire after finishing can be readily controlled simply by adjusting the peripheral speed of the rollers/pulleys.     

拉链式路桥变形缝装置施工技术

简要介绍了拉链式路桥变形缝装置工艺原理及特点,详细总结了拉链式路桥变形缝装置各个施工环节的关键技术及操作要点,指出拉链式路桥变形缝装置施工技术简化了施工步骤,降低了使用成本,具有广阔的应用前景。     

外墙岩棉保温板钢丝网软配筋薄抹灰施工技术

以岩棉保温板、钢丝网软配筋薄抹灰施工技术在某民用建筑工程外墙保温系统施工过程中的应用为例,阐述了此种方法的工艺原理与工艺特点,重点对其工艺流程和操作要点进行了论述,并提出了该工艺的质量与安全控制措施,以促进该方法在行业内的推广应用。     

广西小型水库安全运行管理对策研究

分析了广西小型水库工程存在的年久失修,分布分散,资金、人才缺乏,责权利不清等共性问题,并提出了相应的资金、人才和管护模式等对策。     

The offset codebook (OCB) block cipher mode of operation for authenticated encryption

This article presents an overview of the concepts of and motivation for the OCB block cipher mode of operation. OCB is well suited for IoT, wireless, and other constrained devices where processing time and energy consumption are design issues. The article describes two versions of the OCB algorithm (OCB1 and OCB3) that have been widely accepted.     

Comparative study of LuxY1-xAG (x=0..1) laser ceramics doped with 5% Yb3+

Materials with high thermo mechanical properties are required as laser media for high-powered lasers. One of such materials is lutetium-aluminum garnet (LuAG) doped with ytterbium. In the present work, we discuss for the first time a full comparative study of 5% Yb-doped LuYAG ceramics with variation Lu/Y ratio. Samples were prepared with addition of B₂O₃, MgO and SiO₂ which were used as sintering aids. Grain sizes, shrinkage curves, lattice constants and transmission spectra were measured for all samples. Thermal conductivity was measured in a wide temperature range for all studied samples. Output power of 12 W and 60% slope efficiency were obtained on the 5% Yb:LuAG disk laser.