Synthesis of single-walled carbon nanotubes by arc-vaporization under high gravity condition

Arc-vaporization is one of the common methods to synthesize single-walled carbon nanotubes (SWNTs). However the detailed synthesis mechanism is still not clear, and the synthesis of longer and chirality-selected SWNTs has not been obtained. Here influence of the gravity G = 1 g₀, 2 g₀, and 3 g₀ is studied in order to develop the synthesis method of SWNTs. Simultaneously, calculations of heat convection are also carried out by using a fluid simulation program and the results are compared with the experimental results.     

2号高炉高冶强下的指标优化措施

在高冶强的生产状态下,高炉如何优化各项技术经济指标,降低其成本,从而提高产品竞争力,是现代高炉操作者积极探索的问题。梅钢2号高炉通过精料、优化操作、改进工艺措施等的实施,实现了高炉高冶强下的指标优化。     

自净式电容器性能的研究

对自净式电容器性能,特别是安全性能的担心作出理论上的解释并以试验数据予以证明。     

一种快速提取建筑物高度的方法研究

目前有多种利用单张高分辨率卫星影像计算建筑物高度的模型,但是其适用条件限制了建筑物高度提取的速度和精度。为了解决这一难题,提出利用建筑物投影同名点线段长度估算高度方法,并结合高分辨率影像数据和实测建筑物高度数据对估算结果进行分析。结果表明计算模型正确、精度较高(绝对误差在2.04 m以内)、使用参数较少、普适性强,在城市灾害评估与预测方面具有较大的实用潜质。     

Headquarter-centered common sourcing management through order coordination and consolidation

It is common for subsidiaries of a group company to use the same types of components for producing similar products. Different subsidiary companies may well procure such components from the same suppliers. This paper studies two sourcing management models. One is the Subsidiary-Autonomous Sourcing Management (SD-ASM) where subsidiaries manage their inventories and place purchasing orders independent of each other. The other is the Headquarter-centered Common Sourcing Management (HQ-CSM) where purchasing orders of subsidiaries are processed centrally through some kind of headquarter coordination. In the SD-ASM model, each subsidiary places replenishment orders at a time interval corresponding to their economic order quantity (EOQ). In the HQ-CSM model, two purchasing order management policies are examined. One is the Order Coordination policy in which common replenishment epochs or time periods are proposed by the headquarter and the subsidiaries are encouraged to coordinate the timing of their orders based on the common replenishment epochs. The other is the Order Consolidation policy in which the subsidiaries combine the quantity of their orders and the headquarter places a combined order with the supplier. In the Order Coordination policy, classic RAND heuristic is used to find the best common replenishment epoch and the best replenishment timing of each subsidiary. In the Order Consolidation policy, the optimal order quantity of the combined order is obtained from a mathematical model. The combined order is then allocated to the subsidiaries according to a proportional allocation rule. A series of numerical studies is conducted to compare the costs of the SD-ASM and HQ-CSM policies. The results show that HQ-CSM outperforms SD-ASM in terms of cost and robustness against demand uncertainties. This achievement is largely due to the economies of process (synergistic ordering process), the economies of scale (large order quantity with price discount) and risk pooling effect (transshipments). The results also reveal that the Order Consolidation policy with a combined order always performs better than the Order Coordination policy with common replenishment epochs especially in face of high demand uncertainties and high service level in the global market.     

面向高级综合验证的数据流图提取技术研究

该文主要讨论高级综合系统RTL(register transfer level)级综合结果正确性验证策略的确 定及验证系统设计中DFG(data flow graph)逆向获取算法的设计与实现.算法主要包括4个处 理阶段：FSM(finite state machine)动态分析及控制输出获取;FSM当前状态下数据通道有 效元件分析;数据通道结构到DFG操作结点转换;DFG结点间数据依赖关系分析、共享寄存器 变量分离及有向边的形成.     

Atomic-layer-deposited Al2O3 and HfO2 on GaN: A comparative study on interfaces and electrical characteristics

Al₂O₃, HfO₂, and composite HfO₂/Al₂O₃ films were deposited on n-type GaN using atomic layer deposition (ALD). The interfacial layer of GaON and HfON was observed between HfO₂ and GaN, whereas the absence of an interfacial layer at Al₂O₃/GaN was confirmed using X-ray photoelectron spectroscopy and transmission electron microscopy. The dielectric constants of Al₂O₃, HfO₂, and composite HfO₂/Al₂O₃ calculated from the C-V measurement are 9, 16.5, and 13.8, respectively. The Al₂O₃ employed as a template in the composite structure has suppressed the interfacial layer formation during the subsequent ALD-HfO₂ and effectively reduced the gate leakage current. While the dielectric constant of the composite HfO₂/Al₂O₃ film is lower than that of HfO₂, the composite structure provides sharp oxide/GaN interface without interfacial layer, leading to better electrical properties.     

高压大容量变频技术现状及交——交SDM级联技术简介

本文通过对目前广泛使用的三电平及多电平级联高压变频控制方案技术特点的对比论述，介绍了一种新型高压大容量变频器控制方案，并对该方案的优越性作了介绍。     

高校园区教育资源开发和共享模式探索

针对目前教育资源的短缺和浪费,学生无法享受到比较好的教学资源,学校办学特色不明显等情况,在高校园区逐渐形成了一种教育资源开发和共享的探索模式。各个高校运用自己的能力,共同开发教学资源,并在教育资源差异较大的情况下,进行一定的互补。一般说来,教育资源主要是指在教师资源、课程资源、网络资源和教学设施等方面进行开发和共享。本文主要就高校园区教育资源开发和利用的必要性以及方法问题进行一定的探讨。     

新型莫来石瓷在高密度封装中的应用

描述了低介电常数，低膨胀系数新型莫来石瓷在高密度封装中的应用，从设计考虑、封装结构、工艺及电性能方面进行了探讨，以期获得满足高速、超高速集成电路使用要求的高性能封装。