Solid Shape Research Articles

Microwave sintering of dense and lattice 3Y-TZP samples shaped by digital light processing

Nowadays it is possible to produce ceramic parts with solid and complex shapes with rapid and efficient shaping and sintering techniques. In this paper, 3mol% yttria stabilized zirconia (3Y-TZP) dense and lattice parts were shaped by Digital light processing method (DLP) and densified by conventional (CV) and microwave (MW) sintering. 3Y-TZP samples were MW sintered up to 1550 °C with different heating rates (10, 30, and 50 °C/min) for the dense samples and 30 °C/min for the lattice samples. Controlled thermal cycles with a homogenous heating and no thermal runaway was reached. CV sintering was carried out at 10 °C/min up to 1550 °C. No inter-layer delamination was detected after sintering by the two methods. Both dense and lattice MW-sintered samples reached high final densities (equivalent to obtained values with CV-sintered samples, i.e., ≥98% T.D.), but exhibited a lower average grain size than CV-sintered materials. The different architectures between dense and lattice samples resulted in a different specific absorbed power: the power absorbed by the dense sample is lower than that absorbed by the lattice one meaning that this sample architecture heats up easily.

Functional aerogel coatings on tetrakaidecahedron lattice

This paper reports a new method of functional metamaterial structure fabrication based on ultra-porous aerogel skins introduced on the surfaces of solid tetrakaidecahedron lattices obtained via 3D-printing tools. The solid tetrakaidecahedron lattice shapes are first fabricated from acrylate resin systems using a stereolithography printer. The lattice is then coated with a skin of polyimide gel via sol–gel reaction process, post-curing, and solvent-aging. The aerogel skin is recovered from the gel using supercritical drying. The lattice is found uniformly coated with polyimide aerogel skin as confirmed from examination of surface morphology via scanning electron microscopy and X-ray tomography imaging. The concept is extended to coatings by silica and Kevlar aerogel systems. The mechanical and thermal properties of the resultant materials and a set of applications are discussed.

Numerical Prediction of Turbulent Drag Reduction with Different Solid Fractions and Distribution Shapes over Superhydrophobic Surfaces

The exploration of superhydrophobic drag reduction has been and continues to be of significant interest to various industries. In the present work, direct numerical simulation (DNS) is utilized to investigate the effect of the parameters on the drag-reducing performance of superhydrophobic surfaces (SHS). Simulations with a friction Reynolds number of 180 were carried out at solid fraction values of ϕs=116,111, and 14, and three distribution shapes: aligned, staggered, and random. The top wall is the smooth one, and the bottom wall is a superhydrophobic surface (SHS). Drag reduction and Reynolds stress profiles are compared for all cases. The turbulent kinetic energy budget, including production, dissipation, and diffusion, is presented with respect to the solid fraction and type of distribution to investigate the drag reduction mechanism. The sizes of the longitudinal vortices and formation of hairpin vortices are investigated through the observation of coherent structures. The simulation of a post model is a useful method to study the drag reduction for different solid fraction values and distribution geometries. Our study demonstrates that the drag reduction could acquire 42% with the solid fraction value ϕs=116 and an aligned distribution shape for post superhydrophobic surface geometry. Our study also showed the relationship of the Reynolds stress component (R11, R22, and R33) to the drag reduction with the differences in the solid fraction values and distribution geometry. In which, the R11 component has the most change between an aligned distribution and a random one. The peak value of R11 tends to shift away from the SHS wall. In addition, the analysis of the TKE budget over the superhydrophobic surface was performed, which can be adopted as a useful resource in turbulence modeling based on RANS methodology.

An Experimental Analysis as Replacement of Natural Sand with Bamboo Fibre and M-Sand in Concrete

Abstract: In the present world, concrete has become a significant piece of the development business and the materials which are utilized in causing cement to have advanced because of better nature of concrete and better evaluation of coarse totals. The sand is a significant piece of cement. It is for the most part secured from regular sources. Along these lines the evaluation of sand isn't heavily influenced by us. The solid blocks of M-25 evaluation were tossed right now investigate work and attempted to break down various properties of solid like compressive quality, usefulness and so on. Right now, M-sand (Manufactured sand) is considered as a substitution of characteristic sand by 50, 70 and 90% by weight of sand in solid plan blend in with 5% Bamboo fiber streams as an admixture. This investigation is done at the age of 7, 14, 21 and 28 days restoring of solid shapes and shafts. Right now, general properties of new and solidified cement were attempted and the results were dismembered. As concrete is a focal material for the development business. Right now is seen that the M-sand fundamentally increased the compressive strength of cement with most extreme qualities. Bamboo fiber helps in improving solid properties to maintain a strategic distance from breaks and disappointment. There is an altogether expanded in the compressive quality of 3D squares as we expanded the level of M-sand to 50%,70% and 90% compressive quality increments as 25.1, 26.4, 27 N/mm2 separately for 28 days of curing. There is likewise expanded in the flexural strength of the beam as we expanded in the level of M-sand to 50%, 70% and 90% flexural strength increments as 5.5, 7.02 and 12.9 N/mm2 separately for 28 days of curing.

A Dual Solid Method for Topological Optimization of a Conducting Solid Cooled by Gas Conduction and Surface Radiation

Abstract The topological optimization of a conducting solid simultaneously cooled by (i) conduction to a stationary, radiatively nonparticipating fluid and (ii) surface-to-surface radiation exchange is performed to minimize the overall thermal resistance of the solid configuration. A novel dual solid method (DSM) that utilizes concurrent discrete and continuous descriptions of the solid-phase distribution is introduced. Corresponding discrete and continuous solid models are used to (i) quantify the conduction and radiation heat transfer and (ii) power a density-based topology optimization, respectively. The discrete and continuous models of the DSM are linked by sharing information pertaining to the radiation exchange process. The DSM is the first design method to incorporate the effects of surface-to-surface radiation exchange into the topological optimization of a conducting solid. The influence of the relative strengths of conduction and radiation is illustrated by performing parametric simulations involving various domain boundary temperatures and solid-phase thermal conductivities. In general, use of the DSM to account for radiation heat transfer leads to solid shapes with lower overall thermal resistances and reduced complexity, relative to shapes predicted when radiation is neglected. For the problem considered here, the DSM produces solid shapes that have overall thermal resistances up to 25% smaller relative to overall thermal resistances of shapes determined by topology optimization considering conduction processes only.

Extracting Skeletons of Two-Manifold Triangular Mesh Surface for Planning Skeleton-Guided Five-Axis Surface Inspection Path

Abstract Skeleton curve-guided five-axis sweep scanning is an emerging surface inspection technique with marvelous inspection efficiency. The precondition of applying such a technique to a complex surface is to extract the skeleton curves of a two-manifold surface associated with partitioning the surface into compact surfaces. However, the work on extracting skeletons of two-manifold triangle mesh surfaces is scarce, as existing skeletonization methods mostly focus on either 2D planar shapes or 3D solid shapes. In this paper, we present a new approach to extract the skeletons on a two-manifold triangle mesh with boundaries. The skeletons are formed in the most intuitive manner of wave front propagation which is based on computing the initial value problem of geodesics on a triangle mesh. The step-length of wave front propagation is adaptively controlled to guarantee the appropriate density of skeleton points for having good connectivity. Experiments show that, as a direct application of the proposed skeleton generation and its associated surface partitioning result, the five-axis sweep scanning path of complex free-form surface can be generated conveniently. Experimental results also validate that the computation of our proposed approach is simpler and faster than the state-of-the-art geodesic Voronoi diagram (GVD) method when most of the two-manifold triangle mesh is nearly planar. Additionally, the augmented parameter used for tracing the wave front’s geodesic propagation information is helpful for the skeleton-based surface partition, which is necessary for skeleton curve-guided five-axis sweep scanning.

Effect of La addition on semi-solid microstructure evolution of Mg-7Zn magnesium alloy

Semi-solid billets of Mg-7Zn and Mg-7Zn-0.3La alloys were prepared by semi-solid isothermal heat treatment. The effects of the La element on the as-cast and semi-solid microstructures of Mg-7Zn alloy were investigated. Meanwhile, the effects of isothermal temperature and holding time on the evolution of the semi-solid microstructure of Mg-7Zn-0.3La alloy were also studied. Results indicate that the addition of a small amount of La can significantly refine the as-cast and semi-solid microstructure. During the semi-solid thermal transformation, the size and shape factor of solid particles decrease at first and then increase with the increase of isothermal temperature and holding time. The semi-solid microstructure of Mg-7Zn-0.3La alloy obtained by holding at 605 °C for 30 min is the optimal. The average size of solid particles, shape factor, and solid fraction are 42 µm, 1.45 and 61.8%, respectively. At the same time, a comparative study on the coarsening process of particles in the semi-solid billets of Mg-7Zn and Mg-7Zn-0.3La alloys reveals that the addition of La effectively decreases the coarsening rate of solid particles and restricts the growth of solid particles.

Thermohydraulic Performance of Chevron Pin-Fins

The present study focuses on the optimum design effectiveness in heat removal for small surfaces. Pin-fin made of solid and porous cylindrical shape forming chevron is investigated numerically using the finite element method. The design consists of 3-chevron and 5-chevron configurations connected to a heated block with fluid circulating between the chevron and above them. Variable Reynolds number and pin-fins height ranging from 2 mm to 8 mm are investigated. The full Navier–Stokes equation combined with the energy equation was solved in the presence of the solid pin-fins. The Darcy–Brinkman model with the effective energy equation is used in the presence of the porous pin-fins. The system is solved for Reynolds numbers ranging from 50 to 1000, thus remaining in the laminar regime. Results revealed that the best performance evaluation criterion is higher for the 8 mm porous pin-fins regardless of their permeability. If one ignores the pressure drop and friction contribution, a solid pin-fin having a height of 4 mm showed the best heat absorption mechanism.

Effects of helix shapes and locations on compression capacity of helical piles for offshore foundations

Piles are widely used in marine projects where inappropriate soils are present and soil replacement is not justified economically. Among various pile types, helical piles have been considered as a potential substitution for driven piles in offshore applications. The present paper investigates numerically the effects of tapered helices and inter-helix spaces to achieve the maximum compression capacity in homogeneous and in-homogeneous soil profiles. Both individual and cylindrical failure mechanisms were studied. Tapered helices with decreasing diameters from the top to bottom instead of the same number of identical helices were also studied. Results show that the best inter-helix spacing to helix diameter ratio is two to achieve the greatest pile capacity. Also, the compression load corresponding to 10% of the pile head settlement was found to be reasonable for computing the pile capacity. The results show that tapered helix piles offer better compression capacity than uniform helix piles with the same number of identical helices. In addition, tapered helix piles have almost similar load-settlement variation to solid frustum shape helix piles while in the latter more steel is consumed. In general, the present research highlights that using tapered helices due to their technical and economic performance is advantageous.

FVEstimator: A novel food volume estimator Wellness model for calorie measurement and healthy living

Identifying the calorific value of food requires a correct estimate of its volume and size dimensions. The food volumetric estimation can be done rationally and efficiently by measuring the food dimensions in terms of surface parameters. Food volume estimation can be effectively implemented with a computer vision-based application. The food image size can be estimated for its volumetric and calorific calibration with food area measures. However, studies in this area are limited to finding dimensions of a food item with geometrically regular, irregular, amorphous, and solid food shapes. There is a particular challenge with amorphous food items which do not have any shape and are usually calibrated with subjective container sizes by the dietitians and hence cause relative measures. Instance segmentation techniques are implemented at the pixel level and classify a pixel into a food type leading to higher accuracy in classification and segmentation of food over the background. In this work, mask-based RCNN is employed that helps accurate segmentation of food images with regular and irregular shapes in multi-food dish scenarios. The RCNN based food segmentation is applied as a volume estimator model. It is developed by fine-tuning the pre-trained ResNet model and trained over a dataset of 8 different classes of Indian breakfast food images in all shapes. The estimator model yields a precision of 90.9% for convex-shaped food images, 90.46% for amorphous food images in regular serving containers, and 98.5% to 98.9% for regular shaped (square and circle) food items. The accuracy of the presented volume estimator thus opens opportunities for further research with diverse food types and shapes.

Identification of Wool and Cashmere Fibers by Preparation of Hollow-like Carbon Tubes after Carbonization

ABSTRACT Identification of wool and cashmere has attracted considerable attention in various research fields due to the outstanding properties of fibers. Herein, the hollow-like carbon tubes were facilely prepared by carbonization using the waste wool fibers, which were further characterized by elemental analysis and scanning electron microscope (SEM). After carbonization, hollow-like structures were observed in wool, while cashmere still presented in solid shapes at cross-sectional morphologies. Furthermore, the medulla existed in wool can be pyrolyzed after the carbonization process, which may be an effective way to distinguish the cashmere from wool by their obvious differences in fiber shapes, fiber sizes and residual weights. The effects of temperature on the properties of wool and cashmere were also analyzed. The proportions of hollow wool tubes increased with the rise of temperature, reaching more than 90% at 500°C. Apart from that, the mean diameter of treated wool (16.022 μm) was larger than treated cashmere (8.399 μm), which both shrunk nearly 50% than pristine fibers, and the residual weight of cashmere (68.95%) was higher than wool (62.98%). This method could be extended for identifying specialty fibers like fine yak fiber and yak hair, paving the way for distinguishing protein fibers in multiple areas.

Rapid prediction of fire-induced heat flux on the liners of horseshoe and circular tunnels with longitudinal ventilation at critical velocity

A fast-running model is proposed to predict heat flux from enclosed fires on the concrete liners of horseshoe and circular tunnels that have longitudinal ventilation operating at critical velocity. A wind-tilted 3D discretized solid flame transmits radiation to the visible interior surfaces of the tunnel liner. The emissive power of the solid flame is calculated as a fraction of the fire's total heat release rate. If the calculated flame length exceeds the tunnel height, the solid flame shape is shortened (or “confined”), and its emissive power is amplified proportionally to the geometric confinement. Convective heat flux from the combustion byproducts (which are pushed downstream by the longitudinal ventilation) is represented as a zone of semi-empirical decay from the peak heat flux at the tip of the wind-tilted solid flame shape. Spatial predictions of total heat flux from the wind-tilted Confined Discretized Solid Flame (CDSF) model show good agreement with high-fidelity computational fluid dynamic simulations (which are themselves validated against available test data) for fires with heat release rates ranging from 30 to 300 MW in three tunnel prototype cross-sections. Due to its computational efficiency, the wind-tilted CDSF model is conducive to rapid assessment and stochastic evaluation of tunnel liners for thermo-structural fire effects.

METHODS OF CONSTRUCTION AND DESIGN OF MODERN BUILDINGS USING THE HAYTEK METHOD

A variety of high technologies for the organization of accommodation allow you to build a house that combines original decoration and high functionality. Modern cottages in a high-tech style are distinguished by strict and unique geometry, laconic decor and an abundance of sunlight. Classic high-tech summer house: a combination of solid geometric shapes and large windows with a flat roof. High-tech style house - this opportunity allows you to create a comfortable and economical home.

INFORMS Journal on Applied Analytics Editor’s Statement: A Farewell

<i>INFORMS Journal on Applied Analytics</i> Editor’s Statement: A Farewell

Злокачественная аденомиоэпителиома молочной железы: клиническое наблюдение и обзор литературы

Aim ― to describe the case of malignant adenomyoepithelioma of the breast and to review the corresponding literature, as well as to identify the specific mammographic and ultrasound signs of this malignancy. Material and methods. We report the case of breast tumor witсh histologic phenotype transformed from benign fibroadenoma to the borderline phylloid tumor and finally to the malignant adenomyoepithelioma. Results. At final examination the malignant adenomyoepithelioma showed the multi-nodular structure. Each node represented at mammography and ultrasound (US) the solid internal structure, oval shape and smooth contour. In case of suspicious non-calcified lesion found at mammography that has the solid internal structure and round or oval shape at US it is necessary to consider the following conditions during the differential diagnosis: low-grade invasive ductal carcinoma, mucinous, medillary, clear-cells carcinomas, invasive ductal carcinoma with necrosis or hemorrhage, low-grade adenosquamose carcinoma, metaplastic carcinoma, malignant adenomyoepithelioma and papillary carcinoma, as well as the following rare benign tumors: phylloid tumor, tubular adenoma, fat necrosis, intraductal papilloma, adenoma of the nipple, papilloma-related metaplastic tumors, ductal adenoma, sclerosing adenosis, complex screrozing lesion, and hemangioma. Conclusion. We found no specific imaging signs that allowed to identify the adenomyoepithelioma. This makes necessary to consider both benign and malignant adenomyoepithelioma during the differential diagnosis of round or oval shape solid lesion detected in mammography and/or ultrasound.

A new age technique: In the ecosystem of mixed media in jewelry design

Over the course of its long and complicated history, the meaning of “craft” has changed many times, depending on intersecting social and cultural factors. Craft has been used into art instruction in a variety of ways. Surprisingly, interest in craft has developed only outside of a formal school setting. Wearable art is equivalent to haute couture in terms of fashion. Both haute couture and wearable art are one-of-a-kind items that can be manufactured for a specific consumer. This research is based on the study of a new material called ‘Polymer Clay’. It is a soft material which has multiple uses and can be used in many ways to create beautiful artworks. Polymer clay is made of plasticizers which once heated converts to a solid shape.

Particle-Based Numerical Simulation Study of Solid Particle Erosion of Ductile Materials Leading to an Erosion Model, Including the Particle Shape Effect.

Solid particle erosion inevitably occurs if a gas–solid or liquid–solid mixture is in contact with a surface, e.g., in pneumatic conveyors. Having a good understanding of this complex phenomenon enables one to reduce the maintenance costs in several industrial applications by designing components that have longer lifetimes. In this paper, we propose a methodology to numerically investigate erosion behavior of ductile materials. We employ smoothed particle hydrodynamics that can easily deal with large deformations and fractures as a truly meshless method. In addition, a new contact model was developed in order to robustly handle contacts around sharp corners of the solid particles. The numerical predictions of erosion are compared with experiments for stainless steel AISI 304, showing that we are able to properly predict the erosion behavior as a function of impact angle. We present a powerful tool to conveniently study the effect of important parameters, such as solid particle shapes, which are not simple to study in experiments. Using the methodology, we study the effect of a solid particle shape and conclude that, in addition to angularity, aspect ratio also plays an important role by increasing the probability of the solid particles to rotate after impact. Finally, we are able to extend a widely used erosion model by a term that considers a solid particle shape.

A ‘chisel’ of light carves solid shapes out of a liquid

A ‘chisel’ of light carves solid shapes out of a liquid

High Dielectric Constant SiO2 Nanoparticles

SiO2 nanoparticles of average size 15-20 nm have been synthesized and its dielectric properties have been investigated as a function of frequency (between 20 Hz to 2 MHz). A very high dielectric constant of ca. 14000 at 20 Hz and at room temperature has been observed which is very high compared to the conventional bulk SiO2 particles (ca. 50-100). For this new SiO2 the loss value is found to be less than 1. These SiO2 nanoparticles with high dielectric constant and low loss can be offered its use in constructing high efficient electronic circuit boards and storage devices. Spectra between real and imaginary parts of dielectric constant reveal an inclined line with depressed semicircle. Impedance measurements have been performed to know the electrical properties of the novel SiO2 nanoparticles. XRD, TEM and FTIR characterizations confirm the solid state network structural, morphological shape and size, and chemical functionality of SiO2 respectively. Copyright © 2016 VBRI Press

Incompressibility of face-centered cubic structure in Metallic Nanosolids

A simple and general theoretical model has been constructed to study the bulk modulus ‘B’ of FCC nanoparticles and nanostructures. In order to justify the experimental results of the anomalous behavior of B in nanosolids, this method considers the competing effect of both size and shape of a nanoparticle on B. In this work, the relationship between B and the surface energy has been derived based on the dangling bond energy model. The results show that B depends on size, shape and structure of FCC nanocrystalline solids (nanosolids). Our results show that as the shape changes from spherical to deformed, nanosolids become incompressible and B increases as the size decreases. The obtained theoretical results were compared with the experimental predictions for silver, gold and nickel. A very good agreement between theoretical results and experiments was found for silver and nickel. While in gold, we noticed a deviation from the experiment, which is attributed to extreme deformation of the nanogold.