Development of an undergraduate course – Internet-based instrumentation and control

The objective, strategy, and implementation details of a new undergraduate course, Internet-based Instrumentation and Control, are presented. The course has a companion laboratory that is supported by the National Science Foundation and industry. The combination is offered to senior-level undergraduate engineering students interested in sensing, instrumentation, control, and web programming that want to learn more about the integration of these technologies for solving real-world engineering problems. The course will also be offered to gifted high school seniors with similar interests and can serve as a vehicle to attract them to engineering disciplines. Preliminary assessment of the first offering of the course is encouraging and has shown that the course has achieved success in helping students understand concepts and master basic technologies for developing Internet-based automatic systems.     

Mutagenicity of three agricultural soils

A chemical and biological testing protocol was employed to evaluate the mutagenic potential of the organic compounds extracted from three agricultural soils. The analytical procedures used included bioassays with Salmonella typhimurium and Aspergillus nidulans for the detection of point mutations and a gas chromatography/mass spectrometry/computer system to identify major organic constituents. The extracts of all three soils exhibited mutagenic response in the bioassays. At a dose level of 1000 micrograms per plate, the organic extract of the Bastrop clay induced 434 net revertants; while at the same dose level the Norwood sandy clay and the Sassafrass sandy loam induced 35 and 178 net revertants, respectively, in the Salmonella assay with metabolic activation. In the Aspergillus assay, the extract of the Norwood and Bastrop soils induced a positive response without metabolic activation; this effect was reduced or eliminated in the presence of metabolic activation. Chemical analysis identified a variety of initiators, promotors, inhibitors, and cocarcinogens; however, there were no mutagenic compounds identified in any of the soil extracts. The results of this combined testing protocol indicate that the agricultural soils tested had an inherent level of mutagenic activity, which was not detected by GC/MS analysis alone, and this activity may be related to the past history of agricultural practices, including biocide applications, fertilization, and cultivation.     

Electrical passivation of the silicon surface by organic monolayers of 1-octadecene

The electrical properties of structures consisting of a monolayer of 1-octadecene deposited on the Si surface are investigated depending on the method of passivation of the surface prior to the deposition of the film (hydrogen and ion passivation) and the intensity of illumination which activates the addition reaction of molecules of 1-octadecene to the Si atoms. The monolayer of 1-octadecene on the Si surface is stable and provides the chemical passivation of the surface. Two types of traps are found, namely, traps for holes and electrons, whose density can be varied during deposition of the monolayer by the choice of intensity of illumination and by the method of passivation of the surface. In the case of a low level of illumination and/or the use of the iodine passivation of the surface, the electron traps prevail, and, in the case of high intensity of illumination and/or hydrogen passivation of the surface, the hole traps prevail. It is shown that the use of these films provides conductivity in thin near-surface layers of Si due to providing the mode of flat bands or accumulation of carriers near the surface.     

Influence of pH on the passivation behavior of 254SMO stainless steel in 3.5% NaCl solution

The potentiodynamic polarization measurement of 254SMO stainless steel (UNS 31254) was conducted in 3.5% NaCl solutions with pH ranging from 0.1 to 5. The results indicated that this stainless steel offered excellent pitting corrosion resistance in corrosive environments. Further, it also exhibited various features on the polarization curves in different pH solutions. The electrochemical constant-potential passivation treatment performed at different pH followed by XPS analysis revealed that the primary constituents of the outermost layer of the passive films formed in the weak (pH 5) and strong (pH 0.8) acid solutions are iron oxides and Cr₂O₃ and Cr(OH)₃, respectively. Molybdenum oxides, primarily in the six-valence state, existed in the outermost layer of the passive film. Only very weak signals corresponding to that of nickel oxides were detected in the film formed in the weak acid (pH 5) solution. The ICP-MS analyses indicated selective dissolution of a significant amount of Fe and a few Mo and Ni ions during the passivation treatment in the strong acid (pH 0.8) solution. No Cr dissolution was observed; this indicated that the Cr in the film is relatively stable. XPS depth profiling results showed that a similar bilayer-structured film was formed in both the solutions (pH 0.8 and 5); the outer layer of this film is primarily composed of Cr(OH)₃ and Mo(VI), and the inner layer, Cr₂O₃ and Mo(IV). The results of the examinations of passive film formations and dissolution by XPS and ICP-MS were consistent with the polarization curves.     

钢筋网焊机自动生产线的实时控制

在网焊机自动化生产线的研制中,由于点焊控制器、自动上料机构中焊点总数多、驱动路数多、网格间距小、运行速度快,因而对控制系统的实时性提出了较高要求,用工控机与单片机、PLC组成的网焊机控制系统,在软、硬件实现上采取多种方案有机结合,实现了网焊机生产线的高速实时控制。     

测量机器人GeoCOM接口技术的开发与应用

介绍了测量机器人(TCA2003全站仪)的一些强大功能,分析了其自带的GeoCOM(地理数据通信)接口技术的高级模式,在此基础上利用visual Basic 6.0语言和Access数据库,通过GeoCOM接口对测量机器人进行了二次开发,并应用于某水利枢纽加密控制网的自动观测.最后,通过平差计算得出了一些参考性结论.     

Pressure infiltration of boron nitride preforms with molten aluminum

The infiltration of compacted cubic BN (cBN) with molten aluminum has been investigated as a potential route for a cheap and easy method of manufacturing cBN/metal composites. CBN compacts have been infiltrated with molten Al at a temperature between 670 and 800 °C and pressure of 15 MPa in vacuum. At these temperatures no pronounced interactions between hexagonal and cubic BN with Al was observed, allowing the complete infiltration of cBN with 12 μm mean grain size. After infiltration at 800 °C, the temperature was increased without pressure to convert aluminum into borides and AlN. The hardness of the resulting materials depends on the content of hexagonal, cubic BN and the rate of conversion of Al into borides and AlN. The infiltration height of less than 1 mm obtained from infiltrating the 3 μm cBN powder green compacts gave a hardness of 22.0 ± 0.6 GPa after heat treatment.     

La doping effects on intergrowth Bi2WO6–Bi3TiNbO9 ferroelectrics

La doping effects on intergrowth Bi₂WO₆–Bi₃TiNbO₉ ferroelectric ceramics were studied by X-ray diffraction, electron probe microanalysis and dielectric spectroscopy. It was found that the La³⁺ distribution, ferroelectric phase transition and dielectric relaxation behavior are apparently affected by La doping. With increasing La³⁺ content, the site of dopant ion varies, the grain growth of Bi₅TiNbWO₁₅ is restrained, the Curie temperature is reduced and broadened. Furthermore, two dielectric relaxation loss peaks were observed both in temperature and frequency spectra. The calculated relaxation parameters revealed the oxygen vacancy related to the relaxation process.     

Theoretical Investigation of Time Suboptimal Control of Industrial Manipulators Along Specified Paths

A method for the time suboptimal control of an industrial manipulator from an initial position and orientation to a final position and orientation as it moves along a specified path is proposed. Nonlinear system equations that describe the manipulator motion are linearized at each time step along the path. A method which gives the control inputs (joint angular velocities) for time suboptimal control of the manipulator is developed. In the formulation, joint angular velocity and acceleration limitations are also taken into consideration. A six degree of freedom elbow type manipulator is used in numerical examples to verify the method developed.     

The Role of Acceptance and Job Control in Mental Health, Job Satisfaction, and Work Performance.

Acceptance, the willingness to experience thoughts, feelings, and physiological sensations without having to control them or let them determine one's actions, is a major individual determinant of mental health and behavioral effectiveness in a more recent theory of psychopathology. This 2-wave panel study examined the ability of acceptance also to explain mental health, job satisfaction, and performance in the work domain. The authors hypothesized that acceptance would predict these 3 outcomes 1 year later in a sample of customer service center workers in the United Kingdom (N = 412). Results indicated that acceptance predicted mental health and an objective measure of performance over and above job control, negative affectivity, and locus of control. These beneficial effects of having more job control were enhanced when people had higher levels of acceptance. The authors discuss the theoretical and practical relevance of this individual characteristic to occupational health and performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)