Different Kinds Of Shapes Research Articles

Microstructure, Magnetodielectric, and Multiferroic Properties of xCo0.8Cu0.2Fe2O4−y(0.8BaTiO3–0.2BiAlO3) Composite Ceramics

Herein, xCo0.8Cu0.2Fe2O4−y (0.8BaTiO3–0.2BiAlO3) [xCCFO–y(BTO–BA)] (x = 0, y = 1; x = 1, y = 1; x = 1, y = 2; x = 1, y = 4; x = 1, y = 6) magnetoelectric composite ceramics are synthesized by solid‐state method. The effects of composition on the microstructure, dielectric, ferroelectric and magnetic properties are systematically investigated. Two‐phase structures were confirmed by X‐ray diffraction patterns, which correspond to (BTO–BA) and CCFO phases; a little impurity can be found, and this low‐concentration secondary phase is indexed as BaFe12O19. By scanning electron microscopy, it is found that all the samples show a uniform and relatively dense surface, while the grains show two different kinds of shapes and sizes, which are related with ferroelectric‐phase BTO–BA and magnetic‐phase CCFO. The average grain size of BTO–BA is ≈0.47 μm, and that of CCFO increases with increasing concentration of BTO–BA, and the size of BTO–BA is suppressed with the addition of CCFO. With decreasing the concentration of CCFO, the composites show more and more obvious magnetodielectric effect. The Curie temperature of BTO–BA ceramics is around 150 °C, but this value increases (higher than 150 °C) with the addition of CCFO, implying practical application in high‐temperature devices. The ferroelectric properties of composite ceramics can be optimized by adding BTO–BA.

Computer aided design and manufacturing of low-cost profile cutting tool for cylindrical pipes

The Profile cutting is an in-depth process that takes out piece of chips and transforms it into a particular shape/profile. Cutting is typically carried out on a lathe table using a designed profile tool that is suitable for the product. Profile tool types vary as there are a number of different kinds of shapes may be available in various thickness and grades, so not all can be cut the same way from intricate designs to heavy bulk orders in profile cutting. In this paper we designed and manufactured a profile cutting tool for cylindrical pipe as per our design and shape and tested on Lathe machine. Initially it is modelled by CATIA as per dimensions. The manufactured tool is used for profile cutting of various pipes. It is found that profile cut is very cost effective with less time and accuracy.

Unit Nadarajah-Haghighi Generated Family of Distributions: Properties and Applications

The unit Nadarajah-Haghighi (UNH) class of distributions was developed and its statistical properties investigated in this study. The generator was used to develop the UNH Weibull and UNH log-logistic distributions. For some given parameter values it was realized that the density and failure rate functions of the UNH Weibull and UNH log-logistic distributions can exhibit different kinds of shapes making the distributions suitable for modeling dataset that exhibit some of these shapes. Monte Carlo simulations were performed to examine how the maximum likelihood estimators and ordinary least squares estimators perform with regard to estimating the parameters of the distributions and the results indicated that the maximum likelihood performs better than the ordinary least squares. Applications of the UNH Weibull distribution revealed that it can provide good parametric fit to given datasets.

Using Google Earth\u2122 and Geographical Information System data as method to delineate sample domains for an urban household surveys: the case of Maroua (Far North Region-Cameroon)

BackgroundGetting a random household sample during a survey can be expensive and very difficult especially in urban area and non-specialist. This study aimed to test an alternative method using freely available aerial imagery.MethodsA gridded map and random selection method was used to select households for interviews. A hundred numbered of points were put along the edges of an updated map of Maroua. Then two numbers were randomly draw at a time and a line was drawn between those two numbers. A lot of different kinds of shapes of different sizes obtained were numbered. Ten shapes were randomly draw and the one selected were considered as ‘neighbourhoods’. A grid of 30 m × 30 m was drawn over each and then numbered. 202 grids considered here as households were randomly selected from the ten neighbourhoods for interviews.ResultsOut of 202 households visited, only 4 were found to be something other than a house. In addition, 30 sampled households (14.85%) were abandoned or the occupants had relocated elsewhere. This method resulted in an accuracy level of 72%, its advantage is the ability to generate efficient random sample at relatively low cost as well the time required.ConclusionsThe method proposed in this study was efficient and cost-effective when compared to the infield generation of a household inventory or Global Positioning System (GPS) tracking of households. It can then be used by researchers in low-incomes countries where funding for research is a challenge. However, this method needs to train the investigators on how to use the GPS.

Three-Dimensional Tolerance Analysis Modelling of Variation Propagation in Multi-stage Machining Processes for General Shape Workpieces

The quality control of general shape workpieces has become one of research hotspots because of the increasing diversity of products. The theory of stream of variation (SoV) for machining processes is a successful method in researching variation propagation rule. However, with the consideration of all key elements in manufacturing system, there is no unified and integrated model for workpieces in different kinds of shapes. In this paper, a new variation propagation model in multi-stage machining processes for general shape workpieces is established. It visually demonstrates the variation propagation chain and expands the universality of current SoV models. The connection of all key elements in manufacturing system is defined as an assembly chain, in which the variations are defined and propagated by modified three-dimensional tolerance analysis method. The equivalent conversion of the connection between workpiece and fixture realizes the modelling of general shape workpiece regardless of its machining method and locating scheme. Real experiments validate the effectiveness and accuracy of the new SoV model for different shape workpieces. This model has great potential to be applied toward multi-scale variation modelling, process control, and fault diagnosis for general shape workpieces.

A framework for economies classification and its application to China's regions

AbstractInternational organizations approach economies classification differently. This investigation aims to explore a classification framework, named as thresholds of economy groupings, to obtain the thresholds for easily classifying economies. The framework is applied to classify provinces in mainland China, and the resulting thresholds provide instructional values reflecting macroeconomic situation. One result is that the average value of the relative gross domestic product per capita is roughly equal to the threshold between groupings 3 and 4 of five ones during 2009–2014, which implies regional disparities and balanced policy requirement in China. Furthermore, dynamic development tracks are described as different kinds of shapes.

Formation mechanism of water jets induced by the interaction between bubble and free surface

Explosion in shallow water or small depth water will generate upward water jet, mainly because bubbles generated by explosion will interact with the surface of water. Different underwater depths can result in upward water jets with different kinds of shapes, such as water column, water plume, jet, spall dome, splash, spike, etc. To reveal the formation mechanisms of different types of water jets, a spark bubble experiment platform is set up, and the motions of bubble and free surface are studied experimentally by high-speed photography. The dynamic images for the formation process of the water jets under different initial depths of bubble are obtained. Through theoretical analysis and direct observation of the experimental data, the interaction process between the oscillating bubble and free surface are clarified, and the evolution rule of water jets is obtained. It is found that the key factor affecting the formation of different shapes of the water jets is the superposition of the disturbance of the second bubble pulse and the simple-shape jet induced by the first bubble pulse. Five types of the superpositions are summarized:1) All-fit type, with a large depth of initial bubble, the first and the second bubble impulse fit well to form a smooth and slightly arched water dome; 2) partial-fit type, with a less large depth of initial bubble, higher arched water dome is formed due to the raising effects of second bubble pulse partially fit the initial water dome shape; 3) catch-up type, with a mediate depth of initial bubble, the free-surface jet caused by first bubble pulse will be caught up from the bottom by the second pulse, and form a thin and high velocity jet; 4) run-after type, with a smaller depth of initial bubble, the free-surface jet caused by first bubble pulse will be raised from the bottom by the second pulse, and form a jet with thin head and thick pedestal, sometimes form a crown-type splash; 5) non-superposition type, the depth of initial bubble is so small that the bubble will break up, and no superposition will happen. In summary, the ratio of the initial depth to the maximum radius of bubble is found to be a decisive factor of the superposition type. The initial bubble is described by a dimensionless distance. These conclusions well explain the phenomena observed in experiment, and can provide a new vision and reference to the understanding of the formation mechanism of water jets induced by the interaction between bubble and free surface.

Construction of the Three-Dimensional Virtual Campus Scene’s Problems and Solutions

With the progress of technology, virtual reality technology plays a key role in many domains and has great po- tential and applied prospects. Virtual campus is the reappearance of a real campus's scene by applying virtual reality tech- nology. This technology is aimed to the construction and propaganda of campus. But in the course of construction of the three-dimensional virtual campus scene, owing to numerous things and different kinds of shapes of the real campus, the achievement of virtual campus's system is made difficult. So there are many problems, and if we cannot deal with them properly, they might seriously influence the issue, the application and the use of this system. Combined with examples, the paper analyzes possible problems in the process of building three-dimensional virtual campus scenes, and puts forward some feasible solutions, so as to provide reference for 3D modeling of large scenes.

Nanofabrication of air-spaced field-plate gates with ultra-short footprint

This paper reports our recent work on nanofabrication of air-spaced field-plate (ASFP) gates with ultra-short foot-print using one step electron beam lithography (EBL) combined with reactive ion etch (RIE) for which are suitable for GaN based high electron mobility transistors (HEMTs). Electron beam lithography on a tri-layer stack with PMMA350K/PMMA100K/Al/UVIII is carried out to form the required profile in resist. A low damage RIE dry-etch process is developed to create two different kinds of shapes in the 100nm SiNx layer which serves as a footprint definition and mechanical support to the field-plate. The process enables us to fabricate air spaced field-plates with 60nm foot-print and 50nm air gap. Its advantages over traditional field-plates as well as T shape gate are discussed.

CAD at the Nano Scale

This article focuses on the nanotechnology-related research work at Georgina Institute of Technology. The Georgia Institute of Technology’s Multiscale Systems Engineering Research Group is working to integrate the modeling and simulation features of today’s computer-aided design (CAD) with materials design capability. These integrated features would be available at the nano, meso, micro, and macro scales, which is called multiscale CAD. In future CAD systems, engineers will be able to zoom in to specify material morphology and distributions. Offering the capability of designing materials in CAD requires the representation of many different kinds of shapes. The multiscale CAD would also allow engineers to design better functional materials, such as state-change materials. The geometric modeling of microstructures that make up material is still in its infancy. The efficiency and controllability of complex and porous shapes are the most important research topics for the interactive modeling and design of microstructures.

Finite-Element Simulation of Different Kinds of Wafer Warpages: Spherical, Cylindrical, and Saddle

During the wafer fabrication process, wafers warp into different kinds of shapes, such as spherical, cylindrical, or saddles. These wafers may exhibit a bistable state, that is, if we apply a certain amount of pressure, they snap into another state. Though these shapes are commonly observed in the real world, we have found that it is extremely difficult to obtain these shapes in finite-element tools, such as ANSYS, because some of these states are not numerically preferred solutions. In this paper, we discuss various methodologies we have used to obtain these shapes in ANSYS. The experiments have been carried out in our fabrication lab to measure the wafer warpage at various stages of wafer fabrication. We have found that when the simulated shape matches the experiment, the warpage or maximum out of plane displacement of the wafer obtained from our simulation matches with 1% with the experimental results as well. Furthermore, ANSYS simulations show that backgrinding increases the warpage by the same amount as observed in the experiments. This paper also discusses the limitations of Stoney's formula. The final goal of this paper is to predict how warpage is going to affect the stresses in the silicon (Si) trenches in a device and if any particular trench design is going to lower the amount of wafer warpage, hence the stresses in Si trenches. Section IV shows the simulation results of stresses in the Si trenches. Since it would be computationally infeasible to model a full wafer having all the details of the trench structures, a submodeling technique has been adopted to calculate the stresses in the Si trench wall of a warped wafer. These simulation results are compared with micro-Raman spectroscopy measurements of a warped wafer.

Subdivision surfaces integrated in a CAD system

The main roadblock that has limited the usage of subdivision surfaces in computer-aided design (CAD) systems is the lack of quality and precision that a model must achieve for being suitable in the engineering and manufacturing phases of design. The second roadblock concerns the integration into the modeling workflows, that, for engineering purposes, means providing a precise and controlled way of defining and editing models possibly composed of different geometric representations. This paper documents the experience in the context of a European project whose goal was the integration of subdivision surfaces in a CAD system. To this aim, a new CAD system paradigm with an extensible geometric kernel is introduced, where any new shape description can be integrated through the two successive steps of parameterization and evaluation, and a hybrid boundary representation is used to easily model different kinds of shapes. In this way, the newly introduced geometric description automatically inherits any pre-existing CAD tools, and it can interact in a natural way with the other geometric representations supported by the CAD system.To overcome the irregular behavior of subdivision surfaces in the neighborhood of extraordinary points, we locally modify the limit surface of the subdivision scheme so as to tune the analytic properties without affecting its geometric shape. Such a correction is inspired by the polynomial blending approach in Levin (2006) [1] and Zorin (2006) [2], which we extend in some aspects and generalize to multipatch surfaces evaluable at arbitrary parameter values. Some modeling examples will demonstrate the benefits of the proposed integration, and some tests will confirm the effectiveness of the proposed local correction patching method.

Teaching suggestions for the measurement of area in Elementary School. Measurement tools and measurement strategies

The present study deals with teaching the concept and measurement of area. 106 subjects of the 6th grade of Greek Elementary School measured the area of different kinds of shapes. The subjects were divided into two groups, an experimental group and a control group. In the experimental group, area evaluation was taught in a way that highlighted the conceptual characteristics of area measurement. The teaching intervention and the use of different measurement tools led to different measurement strategies. Moreover, the experimental group used more successful strategies than the control group.

Effect of titanium on second phase precipitation behavior in 9–12Cr ferritic/martensitic heat resistant steels

Effect of titanium addition from 0.003 to 0.140 wt.% on precipitation behavior of MX-type phase in 9–12Cr ferritic/martensitic heat resistant steels was studied. The results show that large titanium-containing MX particles with about 1μm form from liquid metal during the solidification process in high titanium steel. After normalizing at 1100 °C for 1 h, cooled in air and tempering at 750 °C for 1 h, nanometer-sized MX precipitates distribute densely near martensitic lath boundaries in the high titanium steel. Two kinds of nanometer-sized MX precipitates distribute densely and homogeneously in the matrix within lath in low titanium and ultra low carbon steels after the same heat treatment. The relatively larger nanosized MX precipitates have a size more than 30 nm and contain titanium. The number density of the relatively larger nanosized MX precipitates increases with the increasing of titanium content. The relatively smaller nanosized MX precipitates are about 10 nm in size and have two kinds of different shapes: one is cubic and contains titanium, and another rectangular without titanium.

Curvature optical fiber sensor by using bend enhanced method

Deflection curvature measurement can offer a number of advantages compared with the well-established strain measurement alternative. It is able to measure thin structure; fiber has no resistance with force, which leads to a high precision. There are many kinds of curvature gauges with different operation principles. A low-cost curvature optical fiber sensor using bend enhanced method to improve its curvature measurement sensitivity was developed in recent years. This sensor can distinguish between convex bending and concave bending and has a good linearity in measuring large curvature deformation. Whisper gallery ray theory and Monte Carlo simulation are new achievements by computer experiment. The operation mechanism of this curvature optical fiber sensor is presented based on light scattering theory. The attenuation is ascribed to the transmission mode changing by the curvature of the fiber, which affects the attenuation of the surface scattering. The mathematical model of relationship among light loss, bending curvature, surface roughness, and parameters of the fiber’s configuration is also presented. We design different kinds of shapes of sensitive zones; each zone has different parameters. Through detecting their output optical attenuations in different curvatures and fitting the results by exponential decaying functions, the proposed model is demonstrated by experimental results. Also, we compare the experimental results with the theoretical analysis and discuss the sensitivity dependence on bending direction.

The Transient Dynamics of a Small Bubble Rising in a Low Morton Number Regime

AbstractThe effect of initial bubble conditions on the transient dynamics of a small bubble (d = 1.5 mm) rising in water is computationally considered by a fully three‐dimensional direct numerical simulation. The numerical algorithm is based on the coupled level set/volume‐of‐fluid (CLSVOF) method for representing and updating the air‐water interface and the sharp interface approach is used to treat the air‐water interfacial boundary conditions. The transient bubble dynamics are investigated using bubbles with five different kinds of shapes as initial bubble conditions. It is shown computationally that the states of bubble shape, bubble trajectory, and terminal velocities greatly depend on initial conditions. As a consequence, the computational results have led us to conclusions in support of the experimental findings by Wu and Gharib [1] and Tomiyama et al. [2]. That is, the dynamic behavior of a rising bubble in a surface tension force dominant system is effected by the initial conditions.

Optical anisotropy of shaped oriented cobalt nanoparticles by generalized spectroscopic ellipsometry

We report on the application of generalized spectroscopic ellipsometry to the study of oriented prolate ellipsoidal cobalt nanoparticles embedded in a silica thin layer. The elongation of the cobalt particles with ellipsoidal form has been obtained by irradiation of spherical cobalt particles with swift heavy ions. Such a nanostructured medium constitutes an absorbing uniaxial medium with axis oriented 50\ifmmode^\circ\else\textdegree\fi{} from the normal. The rotating polarizer ellipsometer with three elements has been extended to generalized ellipsometry and has been used to determine the anisotropic optical responses of the nanostructured layers. The technique we have developed is based on the acquisition of various spectra for different positions of the elements of the instrument and numerical extraction from these data of generalized ellipsometric parameters. The analysis of the sample is processed in three steps: development of an a priori model and simulation of the optical responses, acquisition of the experimental data and extraction of the generalized ellipsometric parameters, and, finally, numerical fitting of the model. Calculations of the anisotropic electromagnetic response are based on the Berreman formalism. The sample is represented by a stack of three sublayers on a silicon substrate: a top and bottom sublayer made of pure silica and an intermediate sublayer made of a mix of anisotropic cobalt particles and silica. The mix is represented by the generalized Maxwell-Garnett model that gives the effective dielectric constant of the nanostructured medium when this medium is supposed to be made of particles with a single kind of shape in a host medium. To improve our model, a different generalized Maxwell-Garnett formula has been developed to take two different kinds of shapes into account. This approximation has especially been used to represent a medium made of both spherical and ellipsoidal particles. It has been shown that the good agreement between calculated and experimental data can be improved using this different approach of generalized Maxwell-Garnett formula. Despite the complexity of the implanted anisotropic sample, our experimental method and models have lead, on the one hand, to the understanding of this complex anisotropic sample and, on the other hand, to the confident determination of various meaningful parameters that compose this optical response, such as the thicknesses of the sublayers, volume fraction, orientation, and shape factor of the cobalt particles.

Movement behavior in electrostatic separation: Recycling of metal materials from waste printed circuit board

Recycling of metal materials from waste printed circuit board (PCB) is one of the major applications of the electrostatic separation technologies. This paper analyzed the particle shape factor that affected the efficiency of electrostatic separation and addressed influence of the particle shape from both a computational and an experimental point of view. It was performed on three kinds of different shapes of metal materials from scrap PCBs: sphere, cylinder, and flake. Three theoretical models were established based on shapes, and the effect of different shapes on movement behavior was analyzed. Theoretical studies showed that movement behavior of three shape particles was distinguishing: the sphere particles could be projected farther, subsequently cylinder particles, flake could be projected closer, and the experimental results were in good agreement with the theoretical predictions. The results can be used for the design of electrostatic separation technologies and recycling of metal materials from waste printed circuit board.

Optimisation of guide exits by combining MC simulations and optimising routines

In many neutron scattering instruments a convergent guide exit is used to increase the flux on the sample. But at the same time, the divergence of the neutrons increases. The resultant flux on the sample can increase or decrease depending on its distance to the guide exit and the sample size (relative to the guide size). An optimum can be expected for an intermediate convergence. It was our aim to find this optimum for different distances and samples sizes. Therefore, we have performed MC simulations with the software package VITESS. We combined it with a numerical method to find the optimal values. Different kinds of shapes were tested. The influences of starting values and criteria for the optimal exit were checked. For long wavelengths and great distances between exit and sample, the maximum was obtained by diverging exits and not by converging exits. Funnels with a kind of elliptical shape perform better than linearly converging ones. Significant gains can be reached by adapting exits to a certain wavelength range—at the cost of losses in other ranges.

Theoretical study on clusters of magnesium

The energetic and structural properties of neutral magnesium clusters Mgn (n = 2 to 22 and selected clusters up to 309) are investigated by means of density functional theory. The small clusters of sizes n = 4, 10 and 20 show enhanced stability, which is in line with the predictions of the shell model. Larger clusters were selected according to the principle of geometric shell closings; different kinds of shapes and packing types were considered. Among the cluster sizes studied, icosahedral packings are most favourable, which supports the experimental findings. Weak evidence is found for hcp packings to become most stable for large n. The calculated cohesive energies lead to an extrapolated bulk value of 1.4 eV, in reasonable agreement with experiment (1.51 eV). The electronic shell structure of large clusters is discussed in terms of the shell model, which is found to be reliable for up to 40 electrons, while the stability of higher shells is very dependent on the cluster shape.