Use of retroreflectors in the improvement of nighttime highway visibility

A half-century ago retroreflective glass buttons were formally approved to improve the nighttime visibility of highway signs. The development of flexible retroreflective sheetings dates from the late 1930s, and these unique materials permitted the uniform color coding of warning, regulatory, and informational signs. Color coding has contributed to more rapid comprehension and the transmission of fairly complex information. The success of the signing system at night depends on sign brightness, size, and on the natural background against which the driver must see the sign. Research on signing materials is providing improved brightness, while greater understanding of our dependence on the nighttime environment is leading to attempts at characterizing this important variable. The subsequent adjustment of sign luminance will provide traffic signs that more satisfactorily match driver needs.     

Rectification of process measurement data in the presence of gross errors

A systematic strategy is developed for the location of the source and the rectification of gross, biased measurement errors in a chemical process. The proposed strategy proceeds in three levels: (a) A structural analysis of the balance equations identifies subsets of balances with measurements which are suspected to possess gross errors. (b) A sequential analysis of the balance equations with suspect measurements further reduces the size of the problem. Statistical criteria are used in this step. (c) Finally, a sequential analysis of the suspect measurements appearing in the reduced set of balances leads to the identification of the source of the gross errors.The proposed strategy: (i) reduces the size of the data reconciliation problem significantly, even for large-scale chemical processes, (ii) is computationally simple and (iii) it conforms with the general process of variable monitoring in a chemical plant.Numerical examples are presented to clarify the elements of the procedure involved and demonstrate their value and effectiveness in dealing with realistic situations.     

Direct measurement of aerosol glass fiber alignment in a DC electric field

We report non-conducting aerosol fiber (i.e., glass fiber) alignment in a DC electric field. Direct observation of fiber orientation state is demonstrated and quantitative analysis of fiber alignment is made using phase contrast microscopy in four different conditions: (i) dry air and naturally charged fibers, (ii) humid and naturally charged, (iii) humid and neutralized (Boltzmann charge distribution), and (iv) humid and neutralized with an electrostatic precipitator upstream electrodes (i.e., non-charged). The glass fiber aerosols generated by a vortex shaking method were conditioned using a Po-210 neutralizer or humidifier and were provided into a test unit where cylindrical or parallel plate electrodes are used and high voltage is applied to them. Fibers were collected on a filter immediately downstream from the electrodes and their images were taken through an optical microscope to visualize the fiber orientation and measure the alignment angles and lengths of the fibers. The results showed that under all four conditions tested, airborne glass fibers could be aligned to the electric field with different alignment quality, indicating that the glass fibers can be polarized in a steady electric field. In humid air, the fiber alignment along the field direction was observed to be much better and the number of uniform background particles (i.e., randomly oriented fibers) in angular distributions is smaller than that in dry air. Also, it was found that charged fibers in humid air could be better aligned with negligible uniform background than neutralized and non-charged fibers. Possible mechanisms about humidity and charge effects on enhanced fiber alignment are discussed to support the observations. The results indicate that the enhancement of alignment in an electric field would be possible in humid air for other non-conducting fibrous particles having surface chemistry similar to glass fibers.     

Geometrical triple phase boundary length measurement using focused ion beam tomography

In multi‐component materials, triple phase boundary (TPB) is the location where reactions occur. A typical example is the TPB encountered in solid oxide fuel cells at the cathode–electrolyte interface. We proposed a tomographic approach that was developed based on serial sectioning using a focused dual ion beam (FIB) system. For image capture, FIB tomography was coupled with scanning electron microscopy, and differentiation of the composite cathode materials was possible through image contrast adjustment. An algorithm, built on the Hoshen–Kopelman theory, was then applied to measure TPB length. The percentage of the connected TPB line was also calculated with the algorithm for 3D computation. © 2011 Canadian Society for Chemical Engineering     

Reflectance factor measurement systematic errors due to near infrared fluorescence

Orange and red ceramic tiles that are widely used as measurement standards for reflectance factor unexpectedly exhibit near infrared fluorescence. Two measurement methods, illuminating the sample with broadband light and spectrally resolving the reflectance or illuminating the sample with monochromatic light and using a broadband detector, are commonly used to measure reflectance factor. The effect this fluorescence component has on the measured reflectance factor utilizing different measurement methods is analyzed. Published 2010 Wiley Periodicals, Inc. Col Res Appl, 2011     

On the rectification of measurement errors for complex chemical plants: Steady state analysis

An algorithmic approach is developed in the present work, which allows: (i) the classification of the measured and unmeasured process variables, (ii) The estimation of the desired unmeasured variables (using available measurements) in a complex chemical plant and (iii) the rectification of the process measurements. The method is very general and unlike the previous works it can be used in conjunction with linear and nonlinear mass and heat balances.The size of the estimation problem has been reduced significantly. Different algorithms are presented which permit the solution of special practical problems, and stochastic tests are proposed to check the consistency of the process data and detect gross measurement errors.Several examples demonstrate the developed algorithms and indicate the usefulness of the proposed approach, in classifying and estimating the processing variables and adjusting the process data through the utilization of mass and heat balances.     

Flow rate measurement errors in vacuum tubes: Effect of gas resistance to accumulation

Accumulative flow of gas into a vacuum tube has been studied. An analytical model, based on Fick's second law and assuming a constant diffusion coefficient, has been developed to describe the pressure response as a function of time and tube axial position for a constant gas flow rate into a closed vacuum tube. The predicted non‐linear pressure response was verified by conducting short‐term experiments involving a constant gas flow into an instrumented vacuum tube. Initially, the error in flow rate determined using the pressure rise technique was as much as ±100%. At longer time intervals, the constant diffusion coefficient assumption is invalid and the empirical model of Knudsen is used to describe the dependence of the diffusion coefficient on pressure. The governing partial differential equation was solved numerically. The numerical solution accurately predicts the pressure response at any time interval.     

Nature of the prismatic dark interstitial material in Portland cement clinker

The prismatic dark interstitial material in Portland cement clinker is essentially identical with the stable solid solution phase in the system C₃A-NC₈A₃; with rapid cooling, however, metastable extension of the solid solution series takes place, which is the prevailing mechanism of formation of the prismatic phase in works clinkers of low alkali content. The presence of SiO₂ in the interstitial material favors the metastable formation by enhancing the supercooling of the liquid phase in clinker.     

Chapter 1.1 The technical and economic implications of measurement and control errors in water desalination

Dependable control systems are essential for the successful operation of a desalination plant. A well-operated process will prolong plant life, minimize maintenance costs, reduce energy consumption, and achieve the design output of desalted water. Poor process control, on the other hand, will result in scaling, corrosion, and reduced water output. In both thermal and membrane processes, temperatures, pressures, flow rates, and the concentration of additives must be carefully maintained at or near design values. Reliable pH control is essential to minimize corrosion and scale formation.This paper discusses the predominant desalination processes and, for each process, analyzes the influence of deviations in the operating parameters. Where possible, operating limits are indicated. The basic principles outlined herein are equally applicable to the newer variants of the basic desalination plant designs and to the combination processes now appearing on the market.     

Calculation of a flow in prismatic tubes using the planar flow model

The turbulent flow of a Newton liquid in prismatic tubes was represented as a superposition of planar layers. The hydraulic resistance coefficient was calculated from the calculated rate profile in a planar layer. The only fitting parameter was the Reynolds number determined from the dynamic rate and the thickness of the viscous sublayer. The calculated data are in satisfactory agreement with the experimental data on the flow in tubes with a round, trigonal, square, and rectangular transverse section.     

Weak and strong confinements in prismatic and cylindrical nanostructures

Cylindrical nanostructures, namely, nanowires and pores, with rectangular and circular cross section are examined using mirror boundary conditions to solve the Schrödinger equation, within the effective mass approximation. The boundary conditions are stated as magnitude equivalence of electron''s Ψ function in an arbitrary point inside a three-dimensional quantum well and image point formed by mirror reflection in the walls defining the nanostructure. Thus, two types of boundary conditions - even and odd ones - can be applied, when Ψ functions in a point, and its image, are equated with the same and the opposite signs, correspondingly. In the former case, the Ψ function is non-zero at the boundary, which is the case of a weak confinement. In the latter case, the Ψ function vanishes at the boundary, corresponding to strong quantum confinement. The analytical expressions for energy spectra of electron confined within a nanostructure obtained in the paper show a reasonable agreement with the experimental data without using any fitting parameters.     

Geometrical Optimization of the Overlap in Mixed Adhesive Lap Joints

The aim of this research is to optimize the geometry of the overlap in mixed adhesive single- and double-lap joints using a modified version of Bees and Genetic Algorithms (BA and GA). Accounting for adherends Poisson's ratio in the deduced equilibrium equations, the proposed shear lag model gives a more accurate approximation of joint failure load in comparison with Volkersen's solution. The objective functions used in this work are used separately to maximize the load bearing capacity f and the specific strength (f/w) of the joint. This procedure is applied to optimize aeronautical adhesively bonded assemblies, while taking manufacturing constraints into account. The employed constraints are the application of yield criterion on adherends as well as geometrical constraint on the overlap length. The proposed straightforward procedure provides 18 optimal configurations amid a wide range of changes for optimization variables, among which the designer can take a choice, depending on his/her goal. The efficiency of the two employed algorithms, BA and GA, in searching for the optimum geometrical design of the mixed adhesive joints have also been investigated. The results show the more robust and efficient performance of the modified version of BA over GA in such kinds of engineering problems.     

Geometrical non-uniformities in the sensitivity of polycrystalline diamond radiation detectors

Chemical vapour deposited (CVD) diamond is a remarkable material for the fabrication of photon and particle detectors. However, little is known about the perturbations induced by the polycrystalline nature of this material. For this purpose, we have used a micrometer size X-ray beam generated from a synchrotron light source to induce photocurrents in a CVD diamond-based detector. By comparing the measured currents in the device as the beam interaction position is moved on the sample with the topographical image of the surface observed using a scanning electron microscope (SEM), a significant non-uniformity has been observed that could be correlated with the grain structure.     

规整蜂窝载体几何特性研究

蜂窝载体广泛的应用于各个领域，尤其是在治理汽车尾气排放方面的应用。笔者指出了几种常用的蜂窝载体，并建立了求解孔型结构参数的数学模型，提出了影响催化剂载体选择的影响因素，明确了今后的研究方向。     

规整蜂窝载体几何特性研究

蜂窝载体广泛的应用于各个领域,尤其是在治理汽车尾气排放方面的应用。本文提出了几种常用的蜂窝载体,并建立了求解孔型结构参数的数学模型,提出了影响催化剂载体选择的影响因素,明确了今后的研究方向。     

Geometrical properties of porous media

The use of the coefficient characterizing the pore structure of the body in the Darcy formula is analyzed. It is shown by several examples that the translucence factor rather than the porosity factor should be used in the Darcy formula. The relations between these two factors are established by the introduction of a new linear characteristic, namely, the discontinuity factor for different types of porous body.