Comparison Of Optical Scatterometer And Profilometer Techniques For Characterizing Smooth Surfaces

An earlier paper showed that the generalised Nyquist approach, although intrinsically a frequency-response approach, can be deployed to produce an effective multivariable self-tuning methodology. The results, however, were confined to the case of plants with open-loop stable poles and characteristic transfer functions whose branch points are all stable. The purpose of the present paper is to develop the framework that applies to the general case. In particular, consideration is given to fractional representations for the branches of the characteristic transfer functions, and algorithms are developed for both the computation of these representations and their implementation within a self-tuning configuration. Consideration is also given to issues of stability. The results of the paper are illustrated by means of numerical examples and the paper is concluded by a design study based on the open-loop unstable chemical reactor.

This paper presents a systematic development of steady‐state, small‐signal models of interleaved dual boost converter operating in a continuous current mode. These models are derived by employing the well‐known signal flow graph method. This signal flow graph approach provides a means to directly translate the switching converter into its equivalent graphic model, from which a complete behaviour of the converter can easily be studied. Steady‐state performance, small‐signal characteristic transfer functions are derived using Mason's gain formula. The bode plots of audiosusceptibility, input impedance, output impedance, and control‐to‐output transfer functions are determined and illustrated using MATLAB for different values of load resistances, duty ratios. Small‐signal frequency responses obtained from the signal flow graph method are validated with PSPICE simulator results. To validate the signal flow graph modelling equations, sample steady‐state experimental results are provided. Copyright © 2001 John Wiley & Sons, Ltd.

We present a new experimental technique for the separation of dynamic chemical signals based on their frequency domain characteristics. Such a technique can be used to create filters that separate slow signals from fast signals from a common input flow stream. The propagation of time-varying chemical waves through networks of microfluidic channels is first examined. Mathematical models and a set of simple experiments are developed that demonstrate that short microfluidic channels behave as linear delay lines. The observed dispersive broadening and delay behavior can be explained in Fourier space in terms of corresponding phase delay, amplitude decay and characteristic transfer functions. Such delay components can be utilized to implement frequency dependent interference filters. An 8th order PDMS bandpass filter chip demonstrating these ideas was constructed. The filter chip has a central frequency of 0.17 Hz and a bandwith of 0.04 Hz at a flow rate of 4 microL h(-1).

The electrodynamic loudspeaker couples mechanical, magnetic, electric and thermodynamic phenomena. The Thiele/Small (TS) model provides a low frequency approximation, combining passive linear (multiphysical or electric-equivalent) components. This is commonly used by manufacturers as a reference to specify basic parameters and characteristic transfer functions. This paper presents more refined nonlinear models of electric, magnetic and mechanical phenomena, for which fundamental properties such as passivity and causality are guaranteed. More precisely, multiphysical models of the driver are formulated in the core class of port-Hamiltonian systems (PHS), which satisfies a power balance decomposed into conservative, dissipative and source parts. First, the TS model is reformulated as a linear PHS. Then, refinements are introduced, step-by-step, benefiting from the component-based approach allowed by the PHS formalism. Guaranteed-passive simulations are proposed, based on a numerical scheme that preserves the power balance. Numerical experiments that qualitatively comply with measured behaviors available in the literature are presented throughout the paper.

This paper considered identification of vibration characteristics of flexible structure with vector channel periodic lattice filter. We present an algorithm for AR coefficients for the vector-channel lattice filters, and characteristic equation and transfer function are derived from these coefficients. Vibration lattice filter is then constructed from the vector channel lattice filter, and performance of this vibration filter is tested with a test signal which is a combination of many sine waves to compare the performance of scalar and vector channel lattice. Also it is applied to the cantilever data to identify properties of the system, such as natural frequencies and damping ratios, to show its performance.

Ion beam deposition processes were used to influence the microstructure and scattering characteristics of gold and platinum coatings. These metallic coatings were deposited onto super-polished fused silica and Zerodur substrates. They were deposited using thermal evaporation, ion assisted deposition, sputtering, and ion assisted sputtering. The microstructure of these films was characterized using an optical scatterometer, an optical profilometer, a stylus profilometer, scanning tunneling microscopy, and atomic force microscopy. We found that these metallic coatings deposited using ion beam deposition produced lower optical scattering and related surface microroughness.

We report the performance of a 41 X 41-cm2 amorphous silicon-based flat panel detector designed for radiographic imaging applications. The detector consists of an array of photodiodes and thin film transistor switches on a 0.2-mm pitch with an overlying thallium-doped cesium iodide scintillator. The performance of the detector was evaluated through measurement of the frequency-dependent detective quantum efficiency [DQE(f)]. Measurements of the characteristic curve and modulation transfer function (MTF) are also reported. All measurements were made in a radiographic imaging mode with a readout time of 125 ms. We evaluated a total of 15 detectors. One detector was characterized at a range of exposures and at three different electronic gain settings. Measurements of DQE(f) and MTF were also performed as a function of position on one detector. The measured DQE at an exposure of about 1 mR was 0.66 at zero spatial frequency and fell smoothly with frequency to a value of 0.24 at the Nyquist frequency, 2.5 cycles/mm. The DQE is independent of exposure for exposures in the upper 80% of each gain range, but is reduced somewhat at lower exposures because of the influence of additive system noise. The reduction can be controlled by adjusting the electronic gain. For a gain that allows a maximum exposure of 5 mR, the DQE at 0.056 mR was 0.64 at zero frequency and 0.19 at 2.5 cycles/mm. The standard deviation in DQE among measurements on different detectors was less than 0.02 at any frequency. The presampling MTF was 0.26 at 2.5 cycles/mm. The standard deviation in MTF among measurements on different detectors was less than 0.01 at any frequency. Both MTF and DQE were substantially independent of position on the detector.

Kynurenine is the first stable metabolite of tryptophan degradation formed via kynurenine pathway. Inflammation accompanying several disorders can activate kynurenine pathway, therefore increased level of kynurenine is associated with cancer, depression, schizophrenia, encephalopathy, HIV, dementia, amyotrophic lateral sclerosis, malaria, Alzheimer’s, and Huntington’s disease [1]. Kynurenine is an immuneregulatory molecule, which is further converted to other compounds showing biological activity, i.e. neuroprotective or neurotoxic effects on human cells. Studying properties of kynurenine is currently the important topic and might bring new information in context of biological processes [2].The presented work examines the potential of the cation exchange membrane Nafion® (used i.e. in voltammetric analytical approaches) to interact with kynurenine. Nafion is the polymer (ionomer) consisted of tetrafluorethylene or Teflon® backbone with perfluorovinyl ether groups terminated with sulphonate groups. The Nafion allows positively charged species (molecules or cations) to pass through, and at the same time excludes negatively charged compounds [3]. No studies have been conducted on the electrochemical behavior of kynurenine at Nafion covered glassy carbon electrode. Our preliminary studies have shown that kynurenine exhibits efficient adsorption on the Nafion layer, previously deposited by drop coating on the glassy carbon substrate.Voltammetric response of kynurenine strongly depends on the thickness of the Nafion layer. Thus, we attempted to evaluate the relationship between voltammetric signal of the molecule and morphology of the Nafion film deposited in different ways on the glassy carbon substrate (flat and rod electrode). For comparison several different approaches have been utilized for Nafion deposition, i.e. layer of varied thickness of Nafion were deposited on the rod carbon glassy electrode (CGE) or different withdrawal speed of the electrode from the solution of varied concentration of polymer was applied. The great benefit of this technique is possibility to control the thickness at a very high precision level on the whole electrode surface. The morphology surface electrode (roughness and waviness) both with flat and rod shape before and after Nafion deposition were evaluated by optical profilometer, mechanical profilometer, and atomic force microscopy. Moreover, Nation layer thickness on the rod GCE was determined by laser scan micrometer. Morphology characteristic of flat GCE was combined with chemical analysis at atomic and molecular level using complementary methods, such as: TOF-SIMS (time of flight secondary ion mass spectrometry) and XPS (X-ray photoelectron spectrometry). In addition, we propose new methodology for in situ molecular analysis of the rod CGE/Nafion after kynureine adsorption. It combines TOF-SIMS with cyclic voltammetry (CV). In this fashion CGE/Nafion was withdrawn at constant speed from electrolyte contained kynurenine, whilst CV measurements were conducted. When CV experiment was finished, samples were transferred to TOF-SIMS instruments and chemical analysis of different segments with area 100x100 um2 along length of rod were conducted. In that way molecular analysis of every segment surface CGE/Nafion corresponding to applied potential was performed.The results presented here provide new insights in analytical electrochemistry in case of kynurenine behavior on Nafion layer.[1] Y. Chen, G.J. Guillemin, Kynurenine Pathway Metabolites in Humans: Disease and Healthy States, Int J Tryptophan Res. 2009; 2: 1-19.[2] I. Sadok, A. Gamian, M. Staniszewska, Chromatographic analysis of tryptophan metabolites, J Sep Sci. 2017; 40(15):3020-3045.[3] R.K. Nagarale, G.S. Gohil, Vinod K. Shahi, Recent developments on ion-exchange membranes and electro-membrane processes, Adv. Colloid Interface Sci. 2006; 119: 97-130.

In the present study, the effect of tool offset on microstructure and mechanical properties of dissimilar friction stir welding of Al2024 and Al7075 alloys were investigated. In this regard, base metals were welded by FSW under different tool offsetting conditions, 1.5 and 2 mm shifted into Al2024 and Al7075 alloys, respectively, in addition to constant rotation rates and traverse speeds named as 710 rpm and 28 mm/min respectively. The microstructure of different welding zones and fracture surface were investigated by an Optical Microscope (OM) and Scanning Electron Microscopy (SEM), respectively. The results showed that by tool offsetting from the weld center through Al2024, an onion-shaped area has been created and mixture happens completely. However, by tool off-setting towards Al7075, onion-shaped microstructure fails to be formed in the stirred area. From the results of the tensile test, it is presented that maximum tensile strength is obtained in samples with a tool offsetting into the Al7075. With 1.5 mm tool offsetting into Al2024, first, joint tensile strength increases by 22.2 % in comparison to non-offset condition, and then, with more tool offset as much as 2 mm, tensile strength decreases by 22.2 %. In addition, by tool offsetting towards Al7075 by 1.5 and 2 mm, joint tensile strength decreases by 4.5 and 28.5 %, respectively. It is also concluded that in the offset samples towards the 7075 alloy, the microhardness in the HAZ area decreased compared to the microhardness of the offsets samples towards the 2024 alloy. Finally, the best mechanical behavior and microstructural properties were obtained in the sample with the tool offset of about 1.5 mm towards the welded Al2024 base metal (70215 samples) alloy.

Mental hygiene and physical fitness are very important concerning volleyball learning achievement. This study aims to determine volleyball learning achievement which is correlated with (mental hygiene) and level of physical fitness. This research is a type of quantitative research with a correlation approach. The population in this study was 78 students of class 1A, Department of Physical Education, Health, and Recreation, Universitas Riau. The author will use only a portion to represent the existing population. The sampling technique of this research is purposive sampling. The number of samples is 40 people. Methods of data collection uses survey methods with test and measurement techniques. The statistical analysis method used in this study is multi-correlation. It is using a regression analysis test because it analyzes the relationship of more than 2 test variables. The instrument used was a test of physical fitness, mental health questionnaire test, and the results of learning achievement scores of volleyball subject. The mental hygiene instrument has a validity level of 0.595 and a reliability level of 0.522. while physical fitness instruments are adopted of the Indonesian Physical Fitness Test. Test and measurement data were processed using the multiple regression analysis methods. Based on the research results, it can be concluded that physical fitness and mental hygiene have a significant relationship with volleyball learning achievement. These results explain the importance for educators to be able to pay attention to students to improve volleyball learning achievement through providing subject matter by paying attention to physical fitness, using group games to instill a social spirit, sportsmanship, and students' confidence.

In this paper, a surrogate modeling-based acceleration technique for multi-harmonic phase-coherent electrooptic near-field measurements is presented. The implementation uses an adaptive sampling and modeling algorithm instead of the conventional raster scanning approach, which reduces the measurement time by a factor of 9, from 7 hours to 45 minutes, and the number of samples by a factor of 23, from 10556 to 464, while maintaining the average measurement error under 5%. The reduction in measurement time helps to preserve the accuracy of the multi-harmonic near-field measurements, asthe electro-optic measurement system response can drift over time, due to thermal fluctuations in the measurement environment.

Many systems have been devised to characterize smooth surfaces. Some systems measure the optical scatter characteristics of surfaces to provide information concerning surface microstructure; examples include the angle-resolved scatter apparatus (scatterometer) and the total integrated scatter (TIS) apparatus. Other instruments measure the surface profile more directly; examples include the mechanical profilometer (e.g. Talystep and Dektak) and the optical profilometer (e.g. WYKO). The optical profilometer measures the optical phase of a surface to derive a surface profile. If the sample is coated with optically transmitting films, the "surface" is not well defined optically. For these samples, strictly speaking, none of the optical techniques should be used to determine surface microstructure.

Carbons are considered as anode active materials in potassium‐ion batteries (PIBs). Here, the correlation between material properties of disordered (non‐graphitic) and ordered graphitic carbons and their electrochemical performance in carbon||K metal cells is evaluated. First, carbons obtained from heat treatment of petroleum coke at temperatures from 800 to 2800 °C are analyzed regarding their microstructure and surface properties. Electrochemical performance metrics for K+ ion storage like specific capacity and Coulombic efficiency (CEff) are correlated with surface area, non‐basal planes and microstructure properties, and compared to Li+ ion storage. For disordered carbons, the specific capacity can be clearly correlated with the defect surface area. For highly ordered graphitic carbons, the degree of graphitization strongly determines the specific capacity. The initial CEff of graphitic carbons shows a strong correlation with basal and non‐basal planes. Second, kinetic limitations of ordered graphitic carbons are re‐evaluated by analyzing commercial graphites regarding particle size and surface properties. A clear correlation between particle size, surface area and well‐known challenges of graphitic carbons in terms of low‐rate capability and voltage hysteresis is observed. This work emphasizes the importance of bulk and surface material properties for K+ ion storage and gives important insights for future particle design of promising carbon anodes for PIB cells.

The effects of the CNF ratio on the microstructure, corrosion, and mechanical properties of CNF-reinforced diamond cutting tool

DUAL MODEL MATCHING