ATM NIC带宽分配的实现方法

带宽控制是ＡＴＭ技术目前面临的主要难点之一，而其在ＡＴＭ网络接口卡（ＮＩＣ）上的实现机制也是多种多样。本文给出了在ＡＴＭＮＩＣ上采用的一种动态、按需分配带宽的方法，并对其实现机制做了详细的分析。     

几种无限供应的金属/硅体系离子束混合相变

研究了五种无限供应的 Bilayer 膜金属/硅体系中(Ni/Si,Cu/Si,Nb/Si,Mo/Si,Ti/Si),因离子束注入引起的界面原子交混及相变过程。界面温度和注入离子剂量显著影响薄膜相变,在生成各种金属 Si 化物及固溶体时,反应温度和生长激活能大大降低,相变动力学过程与热退火反应不尽相同,诱导离子和基体取向对成相生长也有影响。讨论了相应微观机理。     

AKTS模拟分析硝酸铵的热稳定性

为了研究了硝酸铵(AN)的热危险性,采用差示扫描量热仪(DSC)对AN进行扫描测试,获得了AN在不同升温速率下的热分解规律。运用热动力学分析软件AKTS计算得到AN的热力学和动力学参数,采用风险矩阵法评估了AN热分解的危险性。结果表明:AN起始分解温度为228~250℃,放热量为2 340~2 650 J/g,分解反应活化能为100~175 k J/mol,模拟并计算了AN在绝热条件下反应体系达到最大反应速率所需要的时间为24 h的温度T_(D24)=137.2℃。利用风险矩阵法评估了AN的危险等级为Ⅱ级。针对此危险等级,提出了降低AN储存风险的措施。     

Boiling liquid expanding vapor explosion: experimental research in the evolution of the two-phase flow and over-pressure

In a boiling liquid expanding vapor explosion (BLEVE), the superheating and boiling of the liquefied gas inside the vessel as it fails is important information necessary to understand the mechanism of this type of disaster. In this paper, a small-scale experiment was developed to investigate the possible processes that could lead to a BLEVE. Water was used as the test fluid. High-speed video was utilized to observe the two-phase flow swelling which occurred immediately following the partial loss of containment through a simulated crack. The velocity of the two-phase swelling was measured along with pressure and temperature. It was observed that initially a mist-like two-phase layer was rapidly formed on the liquid surface (~3-4 ms) after the vessel opened. The superheated liquid rapidly boiled and this accelerated upwards the two-phase layer, the whole liquid boiled after about 17 ms form opening. It was supposed that the swelling of the two-phase layer was the possible reason for the first over-pressure measured at the top and bottom of the vessel. From 38 ms to 168 ms, the boiling of the superheated liquid weakened. And from 170 ms, the original drop/mist-like two-phase flow turned into a churn-turbulent bubbly two-phase flow, rose quickly in the field of the camera and eventually impacted the vessel top wall. The force of its impact and "cavitation" and "choke" following with the two-phase ejection were maybe main reasons for the second obvious pressure increasing.     

AlON陶瓷材料的结构、性质及应用

综述了AlON(阿隆 )陶瓷材料的结构、性质、合成及应用情况。认为AlON陶瓷自身优异的性能特点决定了它无论作为功能材料还是作为结构材料 ,都具有广泛的应用潜能 ;同时指出 ,虽然目前AlON陶瓷的研究已经取得了很大的进步 ,但还需对其形成热力学过程、烧结机理、制备工艺等方面进行更深一步的研究     

实时更新的全局一致三维栅格建图

在未知的三维环境中,移动机器人自主导航通常需要实时构建与环境全局一致的栅格地图,而现有大部分系统缺少地图更新策略,构建的栅格地图与实际环境不一致.文中将同步定位与建图模块获得的环境信息以点云形式提供给栅格建图模块处理,同时提出基于关键帧的高效数据结构和地图实时更新策略,实时构建可用于移动机器人自主导航的全局一致的地图.室内动态的实验数据测试表明,文中方法可以有效实时更新地图,生成与环境一致的三维栅格地图,支持其后续的自主导航操作.     

Influence of processing parameters on the structure and properties of barium strontium titanate ceramics

Barium strontium titanate (BST) with the molar formula (Ba_0.8Sr_0.2TiO₃) has been prepared by two different processing methods: mixed-oxide (BST-MO) and reaction-sintering (BST-RS). X-ray powder diffraction study shows differences in grain size and crystal symmetry for both these ceramics. The former shows a tetragonal symmetry while the latter presents a cubic symmetry. The occurrence of polar micro-regions associated with the higher chemical non-homogeneous distribution of ion defects from the influence of the processing parameters is the main reason for the higher peak dielectric constant (K_m), the higher remanent polarization (P_r), the higher coercive field (E_c), the higher peak current density (J_m), and the lower temperature of peak dielectric constant (T_m) in BST-MO ceramics.     

利用硅烷螯合树脂处理重金属废水

介绍了硅烷类螯合树脂处理重金属废水的优点,列举了利用硅烷类螯合树脂处理综合电镀废水的重金属离子的实验结果,结合氢氧化物沉淀法和氧化除氧氰法工艺,可以实现电镀废水零排污。     

上饶市城市“一江两岸”景观设计

上饶市城市"一江两岸"景观设计,以尊重生态、历史和以人为本为设计原则,以实现景观的特色性、亲水性、共享性为理念,打造符合上饶特色的滨水区域.     

A CMOS passive mixer with low flicker noise for low-power direct-conversion receiver

A CMOS passive mixer is designed to mitigate the critical flicker noise problem that is frequently encountered in constituting direct-conversion receivers. With a unique single-balanced passive mixer design, the resulted direct-conversion receiver achieves an ultralow flicker-noise corner of 45 kHz, with 6 dB more gain and much lower power and area consumption than the double-balanced counterpart. CMOS switches with a unique bias-shifting network to track the LO DC offset are devised to reduce the second-order intermodulation. Consequently, the mixer's IIP2 has been greatly enhanced by almost 21 dB from a traditional single-balanced passive mixer. An insertion compensation method is also implemented for effective dc offset cancellation. Fabricated in 0.18 /spl mu/m CMOS and measured at 5 GHz, this passive mixer obtains 3 dB conversion gain, 39 dBm IIP2, and 5 dBm IIP3 with LO driving at 0 dBm. When the proposed mixer is integrated in a direct-conversion receiver, the receiver achieves 29 dB overall gain and 5.3 dB noise figure.