Improper Surface Research Articles

An Efficient Algorithm for Locating TE and TM Poles for a Class of Multiscale Inhomogeneous Media Problems

The Mittag-Leffler (ML) expansion method has been minimally studied in the electromagnetic theory community. Therefore, in this article, the ML expansion functions are effectively utilized to locate initial poles for practical dielectric materials backed by a ground plane. The initial poles from the ML expansion and other existing methods are, then, checked for convergence, and found that the proposed method is highly efficient for electrically thick substrates (ETSs). To understand why, a fundamental and intrinsic convergence (in terms of relative or absolute errors) analysis of ML expansion and Taylor series expansion functions has been carried out and it was found out that the ML expansion converges significantly faster. In addition, Pade approximant has been successfully applied at no computational expense to improve the accuracy of initial pole locations. Moreover, proper and improper surface wave (SW) modes have been clearly distinguished from the poles obtained using the ML expansion method. Finally, the spectral region between leaky and SW poles for ETSs is identified using the initial pole locations obtained from using the ML expansion function on the transverse electric characteristic mode equation.

Excitation of Space Wave, Leaky Wave, and Creeping Waves in Cylindrical Media

The discrete and continuous spectrum in a cylindrical dielectric rod is rigorously characterized taking into account the TE–TM coupling and the longitudinal wavenumber for $\hat {z}$ -, $\hat {\rho }$ -, and $\hat {\phi }$ -directed sources. Pattern characteristics corresponding to space and leaky waves are investigated for all source-polarizations with variation in rod parameters. It is observed that the rod can function as a high-gain antenna and support proper and improper surface waves depending on rod-parameter values. The phase and attenuation characteristics of the axially propagating leaky waves are also investigated delineating the radiating and guided-wave regions of the rod. The beam scanning characteristics for the space and leaky waves with variation in rod parameters are also investigated. The complex azimuthal propagation characteristics of the creeping waves are examined to obtain an insight into propagation regions where such waves are strongly excited.

Comparison of AVHRR aerosol optical depth production against CARSNET data in China

This study presents a dedicated evaluation of a newly released satellite aerosol product derived from Advanced Very-High-Resolution Radiometer (AVHRR) measurements by using the Deep Blue/SOAR aerosol retrieval algorithm. Aerosol product from the Chinese Aerosol Network (CARSNET) is used as the ground truth in the comparison. Comparison of AVHRR and CARSNET aerosol optical depth (AOD) products during 2006–2011 shows that the accuracy and precision of AVHRR AOD demonstrate complicated spatial and seasonal dependence. First, AVHRR AOD is in good agreement with CARSNET AOD over eastern urban areas in China. 45%–78% of data points fall within the expected error range (±0.05 ± 0.25× AOD) over there. Second, in regions with natural vegetation cover and relatively clean environment conditions, low correlation is observed due to small AOD loadings (<0.2 and < 0.6, respectively) and small AOD variations (<1.0). Third, for dust affected arid and semi-arid dry regions and western urban regions, AVHRR AOD products need further great improvement. A large regional variation of AOD bias with increasing CARSNET AOD may be due to insufficient representation of aerosol properties in the algorithm. The systematic underestimation of AVHRR AOD in most sites likely attributes to improper surface reflectance estimation, which should be furthermore improved in the deep blue algorithm. AVHRR has great potential in the retrieval of the historical AOD record from 1979 to the present, therefore, one would expect that AVHRR aerosol products would contribute to furthering our understanding of aerosol effects on climate and environment.

Singularity consideration in the integral equations for contactless inductive flow tomography

PurposeThe contactless inductive flow tomography is a procedure that enables the reconstruction of the global three-dimensional flow structure of an electrically conducting fluid by measuring the flow-induced magnetic flux density outside the melt and by subsequently solving the associated linear inverse problem. The purpose of this study is to improve the accuracy of the computation of the forward problem, since the forward solution primarily determines the accuracy of the inversion.Design/methodology/approachThe tomography procedure is described by a system of coupled integral equations where the integrals contain a singularity when a source point coincides with a field point. The integrals need to be evaluated to a high degree of precision to establish an accurate foundation for the inversion. The contribution of a singular point to the value of the surface and volume integrals in the system is determined by analysing the behaviour of the fields and integrals in the close proximity of the singularity.FindingsA significant improvement of the accuracy is achieved by applying higher order elements and by attributing special attention to the singularities inherent in the integral equations.Originality/valueThe contribution of a singular point to the value of the surface integrals in the system is dependent upon the geometry of the boundary at the singular point. The computation of the integrals is described in detail and the improper surface and volume integrals are shown to exist. The treatment of the singularities represents a novelty in the contactless inductive flow tomography and is the focal point of this investigation.

Optimized Adhesion of Plated Silicon Solar Cell Contacts by F2‐Based Dry Atmospheric Pressure Nano‐Roughening

The adhesion of a plated layer on a substrate is increased by an appropriate roughness at the interface. The paper reports on plated Ni‐Cu‐Ag contacts for silicon solar cells deposited into passivation layer openings that are created using a nano‐second pulsed laser. The adhesion of plated contacts on ns‐pulsed laser‐structured silicon ab initio is not sufficient. This is attributed to an improper surface topography. Atmospheric pressure dry etching in F2 is introduced as plating pre‐treatment to generate a beneficial nano‐roughness on the silicon substrate. Until now, this method is used in silicon photovoltaics only for the formation of black silicon. Process parameters are adjusted to allow the formation of cavities in the range of 5–30 nm. Thereby, the contact adhesion increases. In peel force tests on busbars, the average peel‐force raised from 0.3 to 2 N mm−1. In sheer‐test on finger contacts an increase of maximum sheer force and a decreasing length of the finger displacement are observed. Due to the high etch selectivity between silicon and silicon nitride, no additional etch mask is required to protect the passivation layer. As precursors with a non‐optimized emitter design are used, the roughening procedure affects the solar cell efficiency.

Tailoring Ink-Substrate Interactions via Thin Polymeric Layers for High-Resolution Printing.

The surface properties of a substrate are among the most important parameters in the printing technology of functional materials, determining not only the printing resolution but also the stability of the printed features. This paper addresses the wetting difficulties encountered during inkjet printing on homogeneous substrates as a result of improper surface properties. We show that the wetting of a substrate and, consequently, the quality of the printed pattern, can be mediated through the deposition of polymeric layers that are a few nanometers thick. The chemical nature of the polymers determines the surface energy and polarity of the thin layer. Some applications, however, require a rigorous adjustment of the surface properties. We propose a simple and precise method of surface-energy tailoring based on the thermal decomposition of poly(methyl methacrylate) (PMMA) layers. A smooth transition in the wetting occurs when the thickness of the PMMA layer approaches zero, probably due to percolation of the underlying surface of the substrate, which enables the inkjet printing of complex structures with a high resolution. In particular, the wetting of three substrate-ink systems was successfully adjusted using the thin polymeric layer: (i) a tantalum-oxide-based ink on indium-tin-oxide-coated glass, (ii) a ferroelectric lead zirconate titanate ink on a platinized silicon substrate, and (iii) a silver nanoparticle ink on an alumina substrate.

An Indirect Indentation Method for Evaluating the Linear Viscoelastic Properties of the Brain Tissue.

Indentation experiments offer a robust, fast, and repeatable testing method for evaluating the mechanical properties of the solid-state materials in a wide stiffness range. With the advantage of requiring a minimal sample preparation and multiple tests on a small piece of specimen, this method has recently become a popular technique for measuring the elastic properties of the biological materials, especially the brain tissue whose ultrasoft nature makes its mechanical characterization very challenging. Nevertheless, some limitations are associated with the indentation of the brain tissue, such as improper surface detection, negative initial contact force due to tip-tissue moisture interaction, and partial contact between the tip and the sample. In this study, an indirect indentation scheme is proposed to overcome the aforementioned difficulties. In this way, the indentation force is transferred from a sharp tip to the surface of the tissue slices via a rigid coverslip. To demonstrate the accuracy of this method, the linear viscoelastic properties of the white and gray matters of the bovine brain samples are measured by imposing small cyclic loads at different frequencies. The rate, regional, directional, and postmortem time dependence of the viscoelastic moduli are investigated and compared with the previous results from cyclic shear and monotonic experiments on the brain tissue. While findings of this research present a comprehensive set of information for the viscoelastic properties of the brain at a wide frequency range, the central goal of this paper is to introduce a novel experimentation technique with noticeable advantages for biomechanical characterization of the soft tissue.

Nitrogen-Terminated Diamond (111) Surface for Room-Temperature Quantum Sensing and Simulation.

The nitrogen-vacancy (NV) center in diamond has shown great promise of nanoscale sensing applications, however, near-surface NV suffer from relatively short spin coherence time that limits its sensitivity. This is presumably caused by improper surface termination. Using first-principles calculations, we propose that nitrogen-terminated (111) diamond provides electrical inactivity and surface spin noise free properties. We anticipate that the nitrogen-terminated (111) surface can be fabricated by nitrogen plasma treatment. Our findings pave the way toward an improved NV-based quantum sensing and quantum simulation operating at room temperature.

Vibration Charecteristics of a High Speed Gearbox through Dynamic Analysis

Vibration is the blight of any machine tool industries which creates improper surface finish of the work piece. In this paper, an attempt has been made to design and analyze high speed gearbox used in high speed machining for vibration characteristics under dynamic conditions. Analytical calculations are carried out to arrive at the dimensions of gearbox based on the desired speed ratio. With the help of time history, mesh frequency spectrum and its harmonics, the dynamic response of high speed gearbox is studied through multibody analysis. Modal analysis and critical speed of the high speed gearbox are carried out through simulating software for flexible bodies. Based on the results, the design modifications are carried out to avoid resonance.

Surface coating and characterisation of polyurea for liquid storage

ABSTRACTCompressed hydrogen fuel tanks were used for on-board hydrogen-fuelled vehicles which operate under high pressure and are subject to potential failures associated with pressure vessels. During a failure, hydrogen spills out through the cracks developed in these vessels. Organic materials are used to shield the leakage but mostly it fails due to improper surface and deposition of constituents of coating on the substrate. So in order to eliminate this potential threat a new approach was developed using polyurea coating as protective layer. It is very reactive and cures fast even at low temperature. In this investigation the polyurea coating was characterised using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. In addition to this, nuclear magnetic resonance was done on its binding components to confirm FTIR spectral results.

Failure analysis of an EDM machined mold-printing die used for the production of truck spare parts

Abstract A company produces truck wheel covers as spare parts for the local market. The production of these parts is based on a progressive die performing consecutive forming and selective cutting stages throughout the initial circular steel sheet. The failure occurred to the final stage of manufacturing, as the die marks, by mold-printing, the assembly configuration of the wheel cover onto the wheel rim. The paper presents a thorough failure analysis of the broken tool. The investigation includes preliminary examination, hardness measurements and chemical analysis. In depth microscopic examination was carried out using stereoscope and optical and electron microscopy. The failure mechanism was investigated from macroscopic and microscopic perspective and conclusions regarding the crack initiation and propagation were conducted and analyzed. The causes that led to the total fracture were discussed. The design of the tool and improper surface roughness are considered to be the main causes of the failure. Some complementary recommendations were proposed so to enhance the production rate of the specific tool.

Optical loss by surface transfer doping in silicon waveguides

We show that undoped silicon waveguides may suffer of up to 1.8 dB/cm free-carrier absorption caused by improper surface passivation. To verify the effects of free-carriers, we apply a gate field to the waveguides. Smallest losses correspond to higher electrical sheet resistances and are generally obtained with non-zero gate fields. The presence of free carriers for zero gate field is attributed to surface transfer doping. These results open new perspectives for minimizing propagation losses in silicon waveguides and for obtaining low-loss and highly conductive silicon films without applying a gate voltage.

Modelling of Cutting Force and Robot Load during Machining

Industrial robots are used for many tasks, mainly for material handling, welding and cutting. Robots can be also equipped with other tools for example drill or mill cutter and used for machining. Compared to conventional machines, robots have some advantages, which are: large range, flexibility and speed. On the other hand the greater disadvantage is small stiffness of robotic arms. Also the precision of robot positioning is smaller than modern CNC machines. Nowadays small number of robots are used mainly for machining of soft materials, such as plastic, wood, foam and aluminium. We have also executed some experiments with robot machining including styrodur milling. This technique is similar to rapid prototyping technics. Obtained parts can be used as prototypes. Robots can be used also for machining of hard materials and steel, but that is related with greater cutting force. Thanks they flexibility robots can be used for tasks that are performed by hand by locksmiths. An example of deburring and chamfering of sharp edges were analysed. The burrs and sharp edges that remains after some machining operations must be removed. In most cases that is done by chamfering the edges with hand tools. That tasks requires skilled workers and is physically exhausting and therefore industrial robots can be used to perform that work. But the first problem is prediction of cutting force and selection of proper robot with adequate payload. A mechanistic model of cutting force during milling a chamfer on the edge is presented in the article. Obtained results are similar with other experimental results that are described in the analysed bibliography. Afterwards a methodology for robot selection is explained. Because robot manufacturers give only data for static payload of robot arm, there must be a way to take into account the dynamic cutting force. Some problems that are possible during robot machining are discussed, and some solution are proposed. Because milling force is not constant and still subsequently changes value and direction, it can be the source of vibration. Small stiffness of robot arm combined with vibrations can caused losing of robot position and improper surface after machining. Other problem can be robot programming for machining of curved surfaces in 3 dimensional space. There are same CAM system that can be used for that purpose. Results obtained with developed model can be used for design of robotic cell for chamfering and milling. Normal 0 21 false false false PL X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Standardowy; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";}

A Comparison of Burn Size Estimation Methods’ Accuracy Applied by Medical Students

Background: General practitioners are the first who visit burn patients and they first calculate burn size and required fluid for the patient. Error in calculation can be disastrous. The purpose of this study is to compare four methods of estimating burn size to teach students. Methods: This is a descriptive-analytic study on 37 medical students. Four methods of estimating burn percentage was taught to all students. Students individually estimated four different burn wounds by Rule of nines, patient’s palm, clinician’s palm, and Lund-Browder chart. Students’ results were recorded for the whole body and for organs separately. Data was analyzed by ANOVA test with repeated measures and by SPSS 16. Results: There was a significant difference in 4 methods of estimating burn wound size. Maximum standard deviation in estimation was in patient’s palm method and minimum was in Lund-Browder chart method. Range of improper body surface burn size was 4 to 17 percent. There was a correlation between Lund-Browder chart and rules of nine methods. Wounds larger than 20% were underestimated. There was no significant relationship between the estimation of burn size with gender, average, and body mass index of the students. Conclusion: Considering that failing to use Lund-Browder chart in estimating burn size can decrease the effectiveness of treatment, it is essential to inform general physicians in continuing medical education courses about the importance of choosing the right method to estimate burn size.

Synthesis and properties of nanosilicon stabilized by butyl and perfluorobutyl ligands

Nanocrystalline silicon stabilized by butyl and perfluorobutyl ligands that form improper surface states of silicon nanocrystals were synthesized. The presence of perfluorobutyl ligands on the surface of silicon nanocrystals was proved by IR spectroscopy. Nanocrystals with perfluorobutyl ligands form aggregates, which decreases the efficiency of photoluminescence. The nanocrystals with butyl ligands have smaller size but their photoluminescence can be clearly recorded.

Limitation of a Line-of-Light Online Paper Surface Measurement System

A new prototype device has been developed based on a laser triangulation principle to measure online surface topography in the paper and paperboard industries. It characterizes the surface in a wide spatial scale of topography from 0.09-10 mm. The prototype's technique projects a narrow lineof-light perpendicularly onto the moving paper-Web surface and scattered reflected light is collected at a low angle, low specular, and reduced coherent length onto the CCD sensors synchronized with the laser sources. The scattering phenomenon determines surface deviations in the z-direction. The full-width, at half-maximum of a laser line in cross section is sensitive in computation of the surface topography. The signal processing aspect of the image processing, for example, threshold and filtering algorithms are also sensitive in estimating the accurate surface features. Moreover, improper light illumination, intensity, reflection, occlusion, surface motion, and noise in the imaging sensor, and so forth, all contribute to deteriorate the measurements. Optical techniques measure the surface indirectly and, in general, an evaluation of the performance and the limitations of the technique are both essential and challenging. The paper describes the accuracy, uncertainty, and limitations of the developed technique in the raw profiles and in terms of the rms roughness. The achieved image subpixel resolution is 0.01 times a pixel. Statistically estimated uncertainty (2σ) in the laboratory environment was found 0.05 μm for a smooth sample, which provides a 95% confidence level in the rms roughness results. The depth of field of the prototype is ~2.4 mm.

FATIGUE LIFE ESTIMATION OF A BUTT WELDED JOINT BY S-N APPROACH

A failure analysis based on stress life approach may be useful for predicting the life time of weld in the structure. This study presents an upcoming methodology in new three dimensional Finite Element Model to calculate the fatigue life of weld. Ansys 12.1 simulation software uses stress-life method, based on a static non-linear Structural analysis. The weld material S-N curve were experimentally determined by the Fatigue testing of the dumbell specimen as per 7608 standard. This study assumes that a flaw exist in weld due to welding process, material in-homogeneity, air voids, slugs or impurities in weld, improper surface machining and many more. This material curve is used in simulation to get more accurate results. Thus the fatigue life prediction with the material curves from experimentation will give us more accurate and close to actual failure results.

Antispecular reflections in the backward-wave multimode systems

A specific backward-wave antispecular reflection from the interface of structures or media is analyzed. The reflection coefficients are calculated, and the dominant contribution of the alternative reflection is demonstrated. The supercritical (with respect to angle of incidence and frequency) total reflection and improper surface wave or edge wave in the plate are considered. It is demonstrated that the effect is similar to the Andreev quantum reflection of electrons (which is also alternative) and the elastic reflection of a mechanical top.

Evolution of Interdiffused Gaussian-Shape Nanolayer in Au-Si(111) System at Ambient Condition

Evolution of interdiffused Gaussian-shape nanolayer of Au-Si, formed due to diffusion of Au into Si(111) substrate at ambient conditions, depends strongly on the Si surface pretreatment/passivation conditions. Negligible diffusion in the Au-OSi(111) sample, confirms the strong barrier action of the oxide-layer against diffusion, while large diffusion in the Au-HSi(111) sample compared to that in the Au-BrSi(111) sample suggests that the H-passivated Si(111) surface is more stable. This nature of the Au-Si(111) system is qualitatively similar to that of the Au-Si(001) system but it differs quantitatively. The size, electronegativity and bond-energy of the passivating elements and the number of dangling bonds on the Si surface influence the instability of the Si surface. This instability, parameterized by growth-time of oxide layer alone, can be utilized to tune the amount of diffusion into the sub-surface Si region. The distribution of growth-time and fractional passivated area, which are related to the improper Si surface passivation, are against such control and needs perfection.

Inherently improper surface parametric supports

We identify a class of monomial supports that are inherently improper because any surface rational parametrization defined on them is improper. A surface support is inherently improper if and only if the gcd of the normalized areas of the triangular sub-supports is non-unity. The constructive proof of this claim can be used to detect all and correct almost all improper surface parametrizations due to improper supports.