基于实时UML顺序图的物联网交互模型

物联网是一个集计算、通信和控制于一体的智能系统,它通过监控和收集物理进程信息并将这些信息进行计算和分析,最终生成正确的控制指令用以执行,从而使物理环境变得更加安全和可靠。在物联网中,各物体通过网络连接或者本地连接的方式进行交互,这些交互具有时间性和地域性。物联网的建模和验证是物联网研究中一个重要的领域。文中提出一种基于实时UML顺序图的物联网交互模型,该模型将物联网中所有参与交互的物体建模为交互对象,并且通过实时UML顺序图对交互对象间的交互进行建模。使用时间自动机对交互对象的内部状态变化进行建模,以形成对交互模型的补充。最后根据转换规则将交互模型转换为时间自动机的形式以便于验证。通过一个实例,显示了如何具体应用物联网交互模型。进一步提出了物联网系统应该满足的一些性质,并使用UPPAAL模型检测工具对物联网交互模型进行分析和验证。     

Catalytic decomposition of ammonia gas with metal cations present naturally in low rank coals

A novel hot gas cleanup method to decompose a low concentration of NH₃ to N₂ with metal cations present inherently in low rank coals has been studied with a quartz reactor under the conditions of 750–850 °C, 0.1 MPa and high space velocity of 45,000 h⁻¹. Each coal is pyrolyzed at 900 °C to prepare the char, which is subjected to the decomposition of 2000 ppm NH₃ after pretreatment with H₂. All of five chars examined promote NH₃ decomposition in inert gas, but the promotion effect depends strongly on the kind of char and can correlate more closely with the Fe content than with the Ca content. This result may indicate that the Fe plays a crucial role in the reaction. A commercial activated carbon with a very low Fe content of <0.05 wt% exhibits lower conversion of NH₃ to N₂ than five chars. The TEM pictures reveal the formation of nanoscale particles of Fe and Ca components on a brown coal char that provides the largest catalytic performance. The char maintains the high conversion level of 80% during 25 h reaction at 750 °C and achieves the complete decomposition of NH₃ at 850 °C. The co-feeding of a mixture of H₂, CO, and CO₂ does not change significantly the catalytic activity of the char at a steady state, whereas the coexistence of 2000 ppm H₂S lowers it in the whole range of time on stream. It is proposed by combining the XRD and TPD observations with our previous results that the catalytic decomposition of NH₃ in inert gas with the chars derived from low rank coals proceeds through two cycle mechanisms involving iron metal, iron nitrides, CaO and CaCN₂.     

Effect of Counterions on Synthesis of Mesoporous Silica by the Route of Template

Mesoporous silica materials with ordered hexagonal and parallel-arranged pore channel have been synthesized using cetyl trimethylammonium bromide as a template and Na₂SO₄ as counterions. Their ordered mesostructures were characterized by infrared spectroscopy, X-ray diffraction patterns, scanning electron microscopy, transmission electron microscopy, and nitrogen sorption analysis. The effects of Na₂SO₄ concentration on variations of morphology, specific surface area, and pore size were discussed; the results show that a high concentration of Na₂SO₄ induces the formation of crystal threads with a "tubules-within-tubule" structure, and also leads to mesoporous silica materials with spherical, fabaceous, sheet-like, or prismatic shapes. The results also show that a high concentration of Na₂SO₄ can make the pore size decrease, but cannot change pore wall thickness, demonstrating the stability of the hexagonal-shaped pores.     

Ni-W2C催化葡萄糖氢解制备低碳二元醇反应机理研究

采用HPLC、LC-MS、GC-MS等分析手段对不同工艺条件下Ni/W₂C催化葡萄糖加氢转化的中间产物及终产物进行定性定量分析，研究了葡萄糖加氢转化过程的反应机制和历程。研究发现：葡萄糖加氢转化过程中同时平行发生了加氢、异构和逆向羟醛缩合（氢解）三类反应；葡萄糖发生加氢反应能够得到六元醇且其不会再进一步转化，发生逆向羟醛缩合反应主要生成乙二醇（C₂产物），发生异构反应则可生成果糖，其进行逆向羟醛缩合的产物则为1,2-丙二醇和甘油（C₃产物）；高浓度葡萄糖条件下，其异构产物果糖发生脱水反应生成的5-HMF浓度过高发生聚合，进而导致结焦。根据葡萄糖加氢转化的反应网络，提出了调控反应过程中C₂产物和C₃产物分布的策略，并通过增加催化剂用量来加快果糖脱水的竞争反应速率(加氢、氢解)，进而实现了高浓度（10%，质量分数）葡萄糖的加氢转化。此外，葡萄糖加氢转化过程中存在明显的浓度效应，反应物浓度越低，越有利于发生逆向羟醛缩合反应，反之则有利于发生加氢反应。     

Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part VII. Raman spectroscopic study on the changes in char structure during the catalytic gasification in air

FT-IR/Raman spectroscopies have been used to identify the structural features of Victorian brown coal chars during the gasification in air at 400 °C. The deconvolution of the Raman spectra has allowed us to identify the main structural sites in char where preferential reaction with O₂ takes place. The presence of Na and Ca catalysts is shown to alter the reaction pathways between char and O₂. In the absence of a catalyst, the O-containing functional groups formed in char during gasification were closely associated with the aromatic structure and thus tended to loosen the aromatic structure. The non-catalysed gasification was slow and took place on some specific (especially sp³-rich or sp²–sp³ mixture) sites distributed throughout the char. In the presence of a catalyst (Na or Ca), the O-containing functional groups were not closely associated with the main aromatic structure throughout the char. The catalytic gasification reactions were localised on the sites associated with the catalysts. The preferential removal of smaller aromatic ring systems and the persistence of cross-linking structures in the presence of a catalyst mean that the large aromatic ring systems were increasingly concentrated with little flexibility, affecting the dispersion of catalyst.     

高矣物的特性对双水相相图和头孢氨苄及7-ADCA分配行为的影响

A series of ethylene oxide(EO)-propylene oxide (PO) random co-polymers (EOPO) were used to form aqueous two-phase systems (ATPS) with ammonium sulfate.Effects of EOPO′s properties on the phase separation behaviors and on the partition of cephalexin and 7-aminodesacetoxicephalosporanic acid(7-ADCA) in ATPS were investigated.Both the molar mass and molar ratio of EO to PO of EOPO could greatly influence partition behaviors of cephalexin and 7-ADCA as well as the binodal curve of ATPS. With the increase of molar mass of co-polymer or the decrease of molar ratio of EO to PO,the critical point of ATPS decreased,the binodal curve became more asymmetry,and both cephalexin and 7-ADCA followed the same tendency to partition into the polymer-poor bottom phase.The experimental results shows that it is feasible to partition cephalexin and 7-ADCA in either the polymer-rich top phase or the polymer-poor bottom phase by choosing a specific phase-forming EOPO.     

辛醇接枝碳纳米管复合相变材料的导热性能研究

通过将碳纳米管（CNTs）用混酸进行处理后在其表面以正辛醇（C8H17OH）进行接枝处理,制得接枝C8H17O-CNTs。经红外光谱分析,所得接枝产物出现区别于C8H17OH上的C-O键特征吸收峰,表明接枝成功。在熔融的石蜡（PW）中加入接枝产物并进行搅拌和恒温超声后制得均匀复合物。复合物导热系数的测量结果表明,随温度的升高纯PW和各个组成的复合物的导热系数基本呈现下降趋势。复合物的导热系数基本随C8H17O-CNTs的含量的增加而增大。其中含质量分数为1.0%C8H17O-CNTs的复合物的导热系数较纯PW的导热系数在各个测量温度都提高了大约0.06 Wm-1K-1。     

六自由度模块化机械臂的逆运动学分析

针对自主研发的六自由度(DOF)模块化机械臂,提出一种逆运动学求解方法.根据机械臂的结构特点和运动学约束,对机械臂的运动学进行分析.建立该类型机械臂的正运动学模型,得到了机械臂逆运动学的完整解析解.采用Denavit-Hartenberg(D-H)法对机械臂操作空间进行描述,在考虑机械臂运动学约束的基础上,得到以关节角度为变量的正运动学模型.通过分析正运动学模型的可解性,采用矩阵逆乘的解析法求解机械臂的正运动学模型,得到了该类机械臂逆运动学的完整解析解.通过仿真验证了正运动学模型及运动学逆解的正确性,运动学逆解可以用于机械臂末端执行器的精确定位和运动规划.     

一种新的数据滤波算法

针对常规数据一阶特征估计（滤波）算法的局限性,提出了一种新的滤波算法.算法基于0-1序列思想和时滞原理设计,充分考虑了数据特征之间的相互影响,通过两个意义明确的估值器有效地降低了其他数据特征对一阶特征的影响.应用新算法对某电厂风烟系统数据进行了仿真,仿真结果验证了新算法的有效性.     

红外热像视频的细微变化放大

目的 针对红外热像视频对比度低、成像模糊和难以进行细节观测的缺点,提出一种基于欧拉视角的红外热像视频细微变化放大方法。该方法可以将红外热像视频中细微的色彩变化和动作变化进行放大,将原本人眼无法察觉到的变化清晰地展示出来。方法 该方法首先采用对比度金字塔算法对红外热像视频中每一帧图像进行空域分解,其次对各个尺度的图像进行时域滤波,选择出感兴趣的变化频率并进行线性放大,然后对放大后的信号进行重构,最后对重构得到的图像进行降噪处理,从而获得细微变化放大的红外视频。结果 针对色彩放大和动作放大,实验采集了若干红外热像视频。其中,对人脸侧面的颜色进行放大时,选择像素值变化频率在0.751 Hz 范围内的信号进行滤波并放大,得到像素值变化被放大100倍的视频;对吉他弦的动作进行放大时,选择变化频率在100120 Hz范围内的信号进行滤波并放大,得到弦的动作幅度被放大的视频。结果表明该方法可以使视频中所选择的变化频段得到有效增强。结论 本文方法可以放大红外视频中原本无法观测到的细微变化,并使之清晰呈现,在军用和民用领域中有着广泛用途。