Ce掺杂的有序大孔TiO_2制备及其光催化性能研究

以硝酸铈和异丙醇钛为铈源和钛源,利用溶胶-凝胶和胶晶模板技术合成了一种新型Ce掺杂的有序大孔TiO_2光催化材料,并用扫描电镜、透射电镜、X射线衍射、紫外-可见光谱、比表面积分析等手段对样品结构和形貌进行了表征。最后以甲基橙溶液为对象,在可见光条件下,考察了不同Ce掺杂量的大孔TiO_2材料的可见光催化性能。结果表明,Ce掺杂的大孔TiO_2材料在可见光条件下展现出良好的光催化性能和循环再生能力,当Ce/Ti摩尔比为0.3∶1时,光催化性能最佳,甲基橙降解率可达96%。     

水热法制备N-TiO_2/RGO复合材料及光催化性能研究

采用一步水热法制备氮掺杂负载石墨烯(RGO)的二氧化钛(TiO_2)复合光催化材料(N-TiO_2/RGO),对样品进行XRD、SEM、UV-Vis等表征并以甲基橙为目标降解物进行可见光光催化活性测试。结果表明:N-TiO_2/RGO比同条件下制得的N-TiO_2和TiO_2/RGO具有更好的可见光光催化性能,可见光下照射5h,对甲基橙的降解率可达到95%。     

细菌纤维素负载稀土掺杂二氧化钛复合膜的制备和光催化性能

以细菌纤维素(BC)为载体,用溶胶-凝胶法原位生成稀土镧和铈元素(La,Ce)掺杂的二氧化钛复合膜,以甲基橙为目标降解物,考察了复合膜的光催化活性。结果表明:稀土元素已引入TiO_2/BC复合膜中;掺杂TiO_2的晶型为锐钛矿型;掺杂稀土的TiO_2/BC复合膜的光催化活性比未掺杂的有较大提高;铈掺杂的TiO_2/BC复合膜的光催化性能优于镧掺杂的;Ce~(4+)掺杂的最适浓度为2 mmol/L,而La~(3+)掺杂的最适浓度为5 mmol/L;稀土掺杂的TiO_2/BC复合膜对甲基橙溶液重复降解5次的降解率仍高于70%。     

稀土Dy掺杂对纳米TiO2相变及光催化性能的影响

采用溶胶-微波法制备了稀土元素Dy掺杂的纳米TiO_2复合粉体,采用XRD、拉曼、XPS等手段对样品进行了表征和分析,并以甲基橙的光催化降解为探针反应,探讨稀土Dy掺杂对纳米TiO_2的相变及光催化活性的影响。研究结果表明:稀土掺量为1.3%、经550℃煅烧后制备的样品光催化活性显著提高,对甲基橙的降解率为92%。与未掺杂纳米TiO_2相比,稀土Dy掺杂可以阻碍纳米TiO_2晶粒的生长,增大了比表面积;提高其热稳定性,抑制TiO_2锐钛矿相向金红石相转变;并使TiO_2产生晶格缺陷从而增加纳米TiO_2粉体表面羟基含量和表面氧空位,抑制了光生电子和空穴的复合,增强纳米TiO_2的光催化活性。     

水热法制备TiO_2/ AC复合光催化材料及其性能研究

探究了吸附-光催化协同效应对二氧化钛(TiO_2)-活性炭(AC)复合材料光催化性能的影响。以钛酸四丁酯为原料,活性炭为载体,采用水热法制备出TiO_2/AC二元复合光催化材料。使用XRD、SEM、EDS和FT-IR等检测技术对制备样品进行测试、分析、表征,重点分析了不同水热温度对复合材料晶体结构、形貌、组分含量及表面官能团的变化,并以甲基橙溶液(MO)模拟目标降解物,考察了在紫外光源下TiO_2/AC二元复合材料对甲基橙溶液光催化效率的影响。研究结果显示:负载于AC表面的TiO_2为锐钛矿型;随着水热温度的提高,负载于AC表面上的TiO_2数量增加,粒径增大,分布更加均匀;经紫外光光照180 min后,所有TiO_2/AC复合材料对20 mg/L甲基橙溶液的降解率均达到80%以上,优于纯TiO_2的降解率,表明TiO_2/AC二元协同吸附-光催化效应可明显提高复合材料对甲基橙溶液的降解效率。     

N掺杂介孔TiO2柠檬酸催化合成及其光催化性能研究

采用柠檬酸酸催化溶胶-凝胶法合成了N掺杂介孔TiO_2,并用XRD、HRTEM、XPS、BET、UV-vis等手段表征了N-TiO_2。测试结果表明,煅烧前的样品是无定形TiO_2,低温煅烧后的产物是锐钛矿TiO_2,而750℃煅烧产物是金红石型。少量N元素的掺杂致使TiO_2的吸收带边位置发生少许红移,移向可见光区域。N_2吸附-脱附和光解甲基橙结果显示,N掺杂介孔TiO_2(3.0 at.%)的BET面积为102 m~2/g,孔尺寸大小约为9.8 nm,具有比P25更强的光催化降解甲基橙的能力。     

氮掺杂改性TiO_2多孔薄膜光催化降解4-硝基苯酚

本文采用溶胶-凝胶法制备了N掺杂TiO_2光催化剂,并对N掺杂TiO_2进行了改性,分别以P25、N掺杂TiO_2、改性的N掺杂TiO_2为原料,通过逐步研磨、旋转涂膜以及高温煅烧制得三种多孔薄膜,并对其进行了表征。场发射扫描电子显微镜(FESEM)观察结果显示,煅烧后薄膜呈现显著的多孔结构。以4-硝基苯酚(4-NP)溶液为目标污染物,研究紫外光下TiO_2多孔薄膜的光催化性能,确定最佳降解条件,并研究了薄膜耐用性以及三种薄膜对4-NP的光催化性能的比较。结果表明,三种多孔薄膜中,改性N掺杂TiO_2多孔薄膜光催化性能最佳,10mg/L的4-NP溶液吸附30min,在pH=2条件下180min,降解率达到了90%以上,改性N掺杂TiO_2多孔薄膜单次降解180min,循环使用4次的降解率仍接近80%,显示了薄膜具有较好的可耐用性。     

钴掺杂改性TiO_2的制备及其光催化性能研究

选用六水合硝酸钴((Co(NO3)2·6H2O)为掺杂剂,以钛酸四丁酯(TBOT)为原料,利用水热法制备出钴掺杂改性的TiO_2光催化剂,并利用XRD、SEM、EDS等方法对样品进行表征,研究了Co/TiO_2催化剂的结构、形貌和组成及其对甲基橙的光催化降解性能。结果表明,通过水热法制备的纯TiO_2及Co/TiO_2均为金红石相结构,掺杂Co2+并未改变TiO_2的晶体结构,Co/TiO_2为单分散相的球型,分布较均匀。Co/TiO_2对甲基橙的降解能力相比纯TiO_2有显著提高,当Co2+的掺杂量为1%(mol,摩尔百分含量)时,降解效果最好,最高降解率可达到97.4%。     

F掺杂TiO_2的制备及其光催化性能研究

以钛酸四丁酯为前驱体,氢氟酸(HF)为氟源,采用水热反应法制备了具有可见光活性的氟(F)掺杂二氧化钛(TiO_2)(TiO_2-F),研究了F掺杂对TiO_2光催化性能的影响。采用XRD、Raman spectra、N2-BET、TEM、XPS等手段对催化剂进行了表征。研究结果表明:适量HF的掺入可以明显提高TiO_2高能晶面的暴露比、结晶程度、粒径大小以及对甲基橙(MO)的降解效率,在MO浓度为15mg/L、pH为6.5,降解时间为2.5h,HF添加量为60%(体积浓度)制得的TiO_2-F用量为0.8g/L条件下,TiO_2-F对MO溶液的降解率最大达到62.4%,具有较好的光催化效果。     

TiO_2/ACF光催化降解甲基橙废水性能研究

以活性炭纤维(ACF)为载体,采用溶胶-凝胶法制备活性炭纤维负载二氧化钛复合材料(TiO_2/ACF)。以甲基橙为模型化合物,研究TiO_2/ACF对染料废水的光催化降解活性,考察光照时间、溶液初始浓度、pH值、光强、重复使用次数等因素对甲基橙溶液去除率的影响。结果表明,TiO_2/ACF对甲基橙废水具有较好的光催化降解活性和重复利用性,ACF吸附和TiO_2光催化产生了协同作用。     

凝固科学技术与材料

从凝固科学与实践发展的角度介绍了当前凝固材料体系的基本框架和凝固科学主要发展阶段的基本理论。作为材料科学与工程的基本组成，凝固科学技术正在现代科学理论的基础上针对传统材料的改性提高和新材料的发展需求，以控形、控构、控性为目标开展优质铸件的定向、晶体生长、快凝、深过冷及各种新型和超常领域凝固过程的研究，并介绍了其中某些方面和展望了可能的发展趋势。     

Development and challenges of planning and scheduling for petroleum and petrochemical production

Production planning and scheduling are becoming the core of production management, which support the decision of a petrochemical company. The optimization of production planning and scheduling is attempted by every refinery because it gains additional profit and stabilizes the daily production. The optimization problem considered in industry and academic research is of different levels of realism and complexity, thus increasing the gap. Operation research with mathematical programming is a conventional approach used to address the planning and scheduling problem. Additionally, modeling the processes, objectives, and constraints and developing the optimization algorithms are significant for industry and research. This paper introduces the perspective of production planning and scheduling from the development viewpoint.     

The Candela and Photometric and Radiometric Measurements

The national measurement system for photometric and radiometric quantities is presently based upon techniques that make these quantities traceable to a high-accuracy cryogenic radiometer. The redefinition of the candela in 1979 provided the opportunity for national measurement laboratories to base their photometric measurements on optical detector technology rather than on the emission from high-temperature blackbody optical sources. The ensuing technical developments of the past 20 years, including the significant improvements in cryogenic radiometer performance, have provided the opportunity to place the fundamental maintenance of photometric quantities upon absolute detector based technology as was allowed by the 1979 redefinition. Additionally, the development of improved photodetectors has had a significant impact on the methodology in most of the radiometric measurement areas. This paper will review the status of the NIST implementation of the technical changes mandated by the 1979 redefinition of the candela and its effect upon the maintenance and dissemination of optical radiation measurements.     

PSD和PWELCH函数的分析改进及应用

针对MATLAB中两个内建功率谱密度计算函数psd()和pwelch()计算结果迥异的现象,在功率谱密度估计理论的基础上,根据经典的周期图理论和Welch平均周期图方法,通过详细分析源程序,解析计算方法,发现psd()计算的并不是工程单边功率谱密度,而是采样信号双边谱,故与pwelch()结果迥异,另外pwelch()不能对分段信号数据进行预处理。就上述不足提出了相应的改进措施,比较验证表明改进措施行之有效。     

江澳两地高校文创设计的协同研究与商业实践

目的 探索江门世遗文化的传承、发展和转化的新思路,践行国家在《粤港澳大湾区发展规划》纲要中要求江门承担与港澳地区文化创意合作与开发任务的分工。方法 与澳门高校紧密合作,开展专业培训课程,以开平碉楼为例,从人文视角开展设计研究,梳理开平碉楼的文化脉络,把世遗文化的元素和其背后的文化融入文创产品中,提升文创产品的附加值,推动当地文创产业结构的变革。结果 两地高校构建了稳定的科研团队,开设长期有效的设计培训课程,与景区建立了研究协作关系,帮助景区构建了一套产销研的商业模式。结论 以跨区域高校合作为平台,以文创产品为抓手,依托江澳两地的资源优势,可以构建江门世遗文化全新的品牌形象,最终推动开平世遗文化的活化。     

Creation and motion of dislocations and fracture in metal and silicon crystals

By making a step on one surface ( ) of a rectangular small paralellepiped copper crystal, dislocations could be created by the molecular dynamic method. The dislocation created was not a complete edge dislocation but a pair of Heidenreich-Shockley partial dislocations. Each time a dislocation was created, the stress on the surface was released. Small copper crystals having a notch were pulled (until fracture), compressed and buckled by use of the molecular dynamic method. An embedded atom potential was used to represent the interaction between atoms. Dislocations were created near the tip of the notch. A very sharp yield stress was observed. The results of high speed deformations of pure silicon small crystals using the molecular dynamics are presented. The results suggest that plastic deformation may be possible for the silicon with a high speed deformation even at room temperature. Another small size single crystal, the same size and the same surfaces, was compressed using molecular dynamic method. The surfaces are {110}, {112} and {111}. The compressed direction was [111]. It was found that silicon crystals are possible to be compressed with a high speed deformation. This may suggest that silicon may be plastically deformed with high speed deformation.     

Error and uncertainty in modeling and simulation

This article develops a general framework for identifying error and uncertainty in computational simulations that deal with the numerical solution of a set of partial differential equations (PDEs). A comprehensive, new view of the general phases of modeling and simulation is proposed, consisting of the following phases: conceptual modeling of the physical system, mathematical modeling of the conceptual model, discretization and algorithm selection for the mathematical model, computer programming of the discrete model, numerical solution of the computer program model, and representation of the numerical solution. Our view incorporates the modeling and simulation phases that are recognized in the systems engineering and operations research communities, but it adds phases that are specific to the numerical solution of PDEs. In each of these phases, general sources of uncertainty, both aleatory and epistemic, and error are identified. Our general framework is applicable to any numerical discretization procedure for solving ODEs or PDEs. To demonstrate this framework, we describe a system-level example: the flight of an unguided, rocket-boosted, aircraft-launched missile. This example is discussed in detail at each of the six phases of modeling and simulation. Two alternative models of the flight dynamics are considered, along with aleatory uncertainty of the initial mass of the missile and epistemic uncertainty in the thrust of the rocket motor. We also investigate the interaction of modeling uncertainties and numerical integration error in the solution of the ordinary differential equations for the flight dynamics.     

Miniature and MEMS-type vacuum sensors and pumps

In the paper, the observable trends of the actual research and development of selected types of miniature and MEMS-type vacuum sensors are presented. Some information about the new types of active vacuum gauges, which are offered by the leading manufacturers of the vacuum measurement instruments, is given. Next, the list of MEMS devices that need vacuum for proper operation is presented. Some aspects of vacuum-encapsulation of MEMS devices, on wafer level and package level are shown. The new conceptions of obtaining and maintenance of high and ultra-high vacuum in MEMS devices are described. They concern the conception of integration of a miniature orbitron pump on-chip with MEMS-type device or with vacuum part of the portable advanced instruments such as electron microscope, ion mass spectrometer, and free electron laser.