Interior Ones Research Articles

The potential of biomimetics design in the development of impact resistant material

Ballistic impact resistance is an essential quality for materials to be used in protective shields. In this case, biomimetics design approach was used to improve the existing design of shield by finding solution from nature. Principles were extracted from biological models, such as fish scale, nacre and mantis shrimp, to improve the impact resistance of the shield. These models indicated that a multi-layered material structure shows superior impact resistance properties in case the stiffness of outer layers is much higher than that of inner layers and layer thickness is increased from outer towards inner layers. To verify this statement, materials with carbon fibre reinforced epoxy (CFRP) as the exterior layers and polycarbonate (PC) as the interior ones were designed and numerically analysed. Also pure polycarbonate samples were analysed for comparison purposes. The results showed that biomimetically designed composites had higher ballistic limit velocity than the control specimens for same target thickness.

Microstructural evolution during sintering of copper particles studied by laboratory diffraction contrast tomography (LabDCT)

Pressureless sintering of loose or compacted granular bodies at elevated temperature occurs by a combination of particle rearrangement, rotation, local deformation and diffusion, and grain growth. Understanding of how each of these processes contributes to the densification of a powder body is still immature. Here we report a fundamental study coupling the crystallographic imaging capability of laboratory diffraction contrast tomography (LabDCT) with conventional computed tomography (CT) in a time-lapse study. We are able to follow and differentiate these processes non-destructively and in three-dimensions during the sintering of a simple copper powder sample at 1050 °C. LabDCT quantifies particle rotation (to <0.05° accuracy) and grain growth while absorption CT simultaneously records the diffusion and deformation-related morphological changes of the sintering particles. We find that the rate of particle rotation is lowest for the more highly coordinated particles and decreases during sintering. Consequently, rotations are greater for surface breaking particles than for more highly coordinated interior ones. Both rolling (cooperative) and sliding particle rotations are observed. By tracking individual grains the grain growth/shrinkage kinetics during sintering are quantified grain by grain for the first time. Rapid, abnormal grain growth is observed for one grain while others either grow or are consumed more gradually.

On local quadratic convergence of inexact simplified Jacobi–Davidson method for interior eigenpairs of Hermitian eigenproblems

For the Hermitian eigenproblems, under proper assumption on an initial approximation to the desired eigenvector, we prove local quadratic convergence of the inexact simplified Jacobi–Davidson method when the involved relaxed correction equation is solved by a standard Krylov subspace iteration, which particularly leads to local cubic convergence when the relaxed correction equation is solved to a prescribed precision proportional to the norm of the current residual. These results are valid for the interior as well as the extreme eigenpairs of the Hermitian eigenproblem and, hence, generalize the results by Bai and Miao (2017) from the extreme eigenpairs to the interior ones.

A combined CFD simulation of Plateau borders including films and transitional areas of liquid foams

An integrated computational fluid dynamics model is developed for a combined simulation of Plateau borders, films, and transitional areas between the film and the Plateau borders to reduce the simplifications and shortcomings of available models for foam drainage in micro-scale. Additionally, the counter-flow related to the Marangoni effect in the transitional area is investigated. The results of this combined model show the contribution of the films, the exterior Plateau borders, and Marangoni flow in the drainage process more accurately since the inter-influence of foam’s elements is included in this study. The exterior Plateau borders flow rate can be four times larger than the interior ones. The exterior bubbles can be more prominent in the drainage process in cases where the number of the exterior Plateau borders increases due to the geometry of container. The ratio of the Marangoni counter-flow to the Plateau border flow increases drastically with an increase in the mobility of air-liquid interface. However, the exterior bubbles follow the same trend with much less intensity since typically, the flow is less dependent on the interface of air-liquid in the exterior bubbles. Moreover, the Marangoni counter-flow in a near-wall transition area is less important than an internal one. The influence of air-liquid interface mobility on the average velocity of interior foams is attained with more accuracy with more realistic boundary condition. Then it has been compared with other numerical and analytical results. The contribution of films in the drainage is significant for the mobile foams as the velocity of flow in the film has the same order of magnitude as the velocity in the Plateau border. Nevertheless, for foams with rigid interfaces, film’s contribution in foam drainage is insignificant, particularly for the films near the wall of the container.

A quick method to solve the optimal coordinated voltage control problem based on reduction of system dimensions

This paper presents a new method to speed up the solving process of the optimal coordinated voltage control (OCVC) problem. To this end, after occurrence of a fault, the power system is initially partitioned into interior, boundary and exterior zones by spectral graph partitioning method. Partitioning is based on the fact that voltage instability just after the fault, is a local phenomenon, therefore the variation of boundary and exterior variables is smaller than that of interior ones. Then, the equations of boundary and exterior zones are linearized, the algebraic variables and equations of exterior zone are removed and a considerable decrease in the number of power system equations is obtained which is equal to a reduction in the system dimensions. As a result the determination process of the optimal control actions is fastened. Also, based on the monotonic behavior of long-term voltages, a new method of predicting voltage trajectory is proposed, in which two points are used: the first point referring to the system state just after applying the control actions, which is called jumping point and the final one referring to the steady state of the system. In a case study on the New England 39-bus power system, it was verified that using this method a remarkable increase in calculation speed can be obtained while retaining the system precision.

Expansión urbana en las áreas litorales de América Latina y Caribe

Coastal areas in Latin America and the Caribbean (LAC) are increasingly affected by human settlements. Urban expansion involves a significant change in land use, especially in the coastal area. This research analyses this process from a qualitative and quantitative perspective. Population evolution is studied in all LAC cities with greater than 100,000 inhabitants, differentiating the coastal cities and the interior ones, from 1945 to 2014. The method relates different information sources; from United Nations databases and images from remote sensing. This allows obtaining different urban and coastal process in Latin America and the Caribbean. The results show a coastal area with small cities located close to fragile ecosystems, such as bays, estuaries and mangrove forests. Results obtained highlight management priorities for coastal areas in the LAC region.

Boundary and Interior Nodes in a Fuzzy Graph Using Sum Distance

In this paper, the concepts of boundary nodes and interior ones are introduced in a fuzzy graph based on sum distance with relationship among boundary nodes, interior nodes, fuzzy cutnodes and complete nodes. It is observed that fuzzy cutnodes can be boundary nodes and there are nodes in G, neither boundary nodes nor interior ones. It is verified that a complete node need not be a boundary one and a node which is a boundary one of all other nodes need not be complete. In fuzzy trees, it is observed that fuzzy end nodes need not be boundary ones and vice versa. It is verified that in a complete fuzzy graph there exist at most one node which is not a boundary one. Also boundary nodes of a self centered fuzzy cycle are identified together with interior nodes of a complete fuzzy graph.

The self-similarly expanding Eshelby ellipsoidal inclusion: II. The Dynamic Eshelby Tensor for the expanding sphere

The field solution of a self-similarly (subsonically) expanding Eshelby ellipsoidal inclusion obtained in Part I is evaluated for the case of the expanding spherical inclusion under general uniform eigenstrain ϵij⁎ in self-similar motion R=υt, starting from zero dimension. The particle velocity in the interior domain vanishes and the displacement gradient is constant exhibiting the Eshelby property in the self-similar dynamic case. All components of the interior and exterior Dynamic Eshelby Tensor are obtained for the sphere, with the interior ones depending on the wave speeds and the expansion speed of the inclusion, while the exterior ones depend, in addition, on the variable of self-similarity r/t and the direction of the field point. By a limiting procedure the static Eshelby tensor both interior and exterior is retrieved, thus making the static inclusion a special limit of the dynamic self-similarly expanding one. The jump of the particle velocity across the moving inclusion boundary is obtained, and it depends only on the wave and expansion speeds and the direction of the normal.

Performance improvement of natural draft dry cooling system by interior and exterior windbreaker configurations

Ambient winds are basically unfavorable to the thermo-flow performances of natural draft dry cooling system, and may result in a reduced thermal efficiency for the power generating unit in power plants, so it is of benefit to the natural draft dry cooling system to propose the measures against the adverse effects of ambient winds. For a typical natural draft dry cooling system, the computational models of the flow and heat transfer of cooling air coupled with the energy balances of circulating water and exhaust steam are developed, by which the performance improvement due to the interior and exterior windbreaker configurations is investigated. The flow and temperature fields of cooling air, the flow rate and heat rejection of each sector, the outlet water temperature of heat exchanger for the natural draft dry cooling systems with and without windbreaker configurations, and the corresponding turbine back pressures are obtained. The results show that the exterior windbreakers are superior to the interior ones in thermo-flow performances. The turbine back pressure can be reduced by the windbreaker configurations in the presence of ambient winds, especially at high wind speeds.

Displacement transfer from borders to interior of a plate: A crustal transect of Iberia

A N-S crustal transect of the whole Iberian Plate is presented. The displacement transfer during the Alpine deformation from the border ranges (Cantabrian and Betic chains) toward the interior ones was analyzed by means of balanced crustal sections. Inconsistencies in shortening values between upper and middle-lower crust in the Cantabrian Mountains (Basque–Cantabrian Zone) imply a mid-crustal detachment transferring orogenic shortening southward toward the Spanish Central System. Depending on the shortening value attributed to the Central System, this mid-crustal detachment could involve the entire Iberian Plate, connecting the Cantabrian Mountains and the Betic Chain. The very small crustal root in the Central System can be explained as a result of the tectonic load caused by the upper crustal shortening that was transferred from the border ranges. We conclude that a simple shear model, rather than a pure shear with lithospheric folding, better explains the whole Iberia deformation. Finally, the total Alpine shortening of the Iberian Plate is estimated between 267 and 292km.

ADAM: a general method for using various data types in asteroid reconstruction

We introduce ADAM, the All-Data Asteroid Modelling algorithm. ADAM is simple and universal since it handles all disk-resolved data types (adaptive optics or other images, interferometry, and range-Doppler radar data) in a uniform manner via the 2D Fourier transform, enabling fast convergence in model optimization. The resolved data can be combined with disk-integrated data (photometry). In the reconstruction process, the difference between each data type is only a few code lines defining the particular generalized projection from 3D onto a 2D image plane. Occultation timings can be included as sparse silhouettes, and thermal infrared data are efficiently handled with an approximate algorithm that is sufficient in practice due to the dominance of the high-contrast (boundary) pixels over the low-contrast (interior) ones. This is of particular importance to the raw ALMA data that can be directly handled by ADAM without having to construct the standard image. We study the reliability of the inversion by using the independent shape supports of function series and control-point surfaces. When other data are lacking, one can carry out fast nonconvex lightcurve-only inversion, but any shape models resulting from it should only be taken as illustrative global-scale ones.

On Morley’s Trisector Theorem

a þþ; b; c a; b þþ; c a; b; c þþ a; bþ; cþ aþ; b; cþ aþ; bþ; c þ; þ; þ because in each case these angles add to ða þ b þ cÞ þþ 1⁄4 180 . These triangles, so far determined only up to similarity, are illustrated in Figure 1. We can scale them so that the red lines in that figure all have the same length. The red lines from A to BC are the two lines through A that make angle aþ with BC , and are the same length since they form an isosceles triangle. (I call drawing such lines ‘‘dropping non-perpendiculars of angle aþ’’.) If one of the angles of ABC is obtuse—as is C in the figure—then the two angles at the feet of these non-perpendiculars (here cþ) are exterior angles of the isosceles triangle they form, rather than interior ones, but this does not affect the proof.

First-principles study of stability and properties on β-SiC/TiC(111) interface

The interfacial properties of β-SiC/TiC(111), such as work of adhesion, interface energy, fracture toughness, bonding nature, were investigated using first-principles calculations. Twenty four interface models with different terminations, carbon sublattice, and stacking sites were investigated. The thermodynamic stability of SiC/TiC(111) decreases as the order of C/C, Si/Ti, C/Ti, and Si/C terminations. The C/C-terminated top-site-stacked models (CCU3, CCT3) are most stable with the largest work of adhesion, smallest interface energy, and largest interfacial fracture toughness. The interfacial fracture toughness is predicted as 3.6 ∼ 4.3 MPa·m1/2. The valence electron density and partial density of states indicate that the interfacial bonding is mainly contributed from covalent C-C interactions caused by the hybridization of C-2p. The interfacial Si-C and Ti-C bonds are less covalent and much weaker than the interior ones, and the interfacial bonds are more inclined to decompose. The carbon layer is likely to form on the interface due to the decomposition. Our calculation results are compared and in line with previous investigations.

Effect of Multistep Processing Technique on the Formation of Micro‐defects and Residual Stresses in Zirconia Dental Restorations

The clinical failures of zirconia dental restorations are often caused by extrinsic artifacts introduced by processing. The aim of this study was to investigate the micro-defects and residual stresses generated during the multistep process of zirconia dental restorations. Thermal spray granulated 3Y-TZP powders were dry pressed by two tools exhibiting distinctly different Young's moduli, cold isostatic pressed (CIP-ed), and pressure-less fully sintered. The green bodies pressed by a stiff tool were treated with different procedures: direct milling (green milling) followed by fully sintering; half-sintering and milling (raw milling) with or without fully sintering; and fully sintering followed by grinding. The fully sintered 3Y-TZP crowns were clinically adjusted using both a diamond bur and SiC bur, respectively. Phase composition and microstructure of the pressed, milled, and ground surfaces were studied by XRD and SEM. Tetragonal phase was the main phase of all detected 3Y-TZP specimens. Excessive residual stresses introduced by raw milling and grinding were confirmed by a strained T (111) peak, monoclinic phase, and obviously changed I(002)t /I(200)t ratio. The residual stresses would form a compressive stress layer, while it was too shallow to inhibit crack propagation even for ground specimens. Large voids with high-coordination numbers were the common packing micro-defects. Once formed, they were barely healed by CIP-ing and sintering. A stiff pressing tool was confirmed to be useful for reducing the surface packing voids. Milling removed the surface voids, but was no help for the interior ones. Raw milling introduced more serious chippings, most originating from the existing packing voids, than green milling due to its brittle failure and was less recommended for production. Grinding dense 3Y-TZP caused surface grain refinement and much more severe micro-defects, especially when clinical adjustment was applied by diamond bur compared to SiC bur. Micro-defects and residual stresses are introduced and accumulated through the entire production chain and determine the final microstructure of zirconia dental restorations. Several procedural improvements are offered and expected to reduce processing micro-defects.

Experimental study of an innovative element for passive cooling of buildings

Abstract The use of passive cooling techniques has been seen as one of the solutions that can help to reduce energy consumption in the building sector. An innovative element that allows the combined use of two passive cooling techniques, evaporative cooling and night ventilation, is proposed in the present work. In order to optimize the use of those techniques it was decided to include in the element configuration a core component with latent heat storage capabilities. Briefly it can be said that the element is composed by the accumulating core, consisting of a cement mortar vertical panel impregnated with paraffin, with two adjacent channels for air circulation. The element, whose configuration should allow its integration into the buildings envelope, has a parallelepiped shape with one air inlet and one air outlet in each of its opposite faces, the exterior and the interior ones. The core surface adjacent to the exterior channel is maintained continuously wetted by a water sprinkler system integrated in the element. The airflow in each channel is provided by tangential fans mounted on top of the element. The paraffin wax used corresponds to a commercial wax with phase transition range near 21 °C, slightly below typical comfort temperatures. A prototype of the element was constructed and subjected to a series of experimental studies that aim to know its response in operating conditions similar to real ones. These studies took place in a climate chamber for a wide range of conditions. The results suggest that the proposed element exhibits the potential for passive cooling of buildings. It was concluded that the paraffin wax incorporation in the cement mortar core has substantially improved the capacity of thermal energy accumulation of the element, that the evaporation process on the outside surface of the core provides a substantial temperature reducing of the core, and that its use also during night-time periods allows to cool the core well below the outside temperatures, thus maximizing the possibility of application of night ventilation.

Transboundary pollution in China: a study of polluting firms' location choices in Hebei province

AbstractTransboundary pollution is a particularly serious problem as it leads people located at regional borders to disproportionately suffer from pollution. In China, where the environmental policy is decentralized and where environmental conflicts between provinces have occurred several times, transboundary pollution is likely to exist. However, until now, nearly all the studies have focused on developed countries. In this paper we study whether transboundary pollution problems exist in China. To do so, we estimate whether, within Hebei province, polluting firms are more likely to set up in border counties than in interior ones. The estimations of a count-data model allow us to conclude that border counties are more attractive destinations for polluting firms than counties located within the province. Moreover, it appears that this effect has strengthened over time.

X-ray microtomography study of the compaction process of rods under tapping

We present an x-ray microtomography study of the compaction process of cylindrical rods under tapping. The process is monitored by measuring the evolution of the orientational order parameter, local, and overall packing densities as a function of the tapping number for different tapping intensities. The slow relaxation dynamics of the orientational order parameter can be well fitted with a stretched-exponential law with stretching exponents ranging from 0.9 to 1.6. The corresponding relaxation time versus tapping intensity follows an Arrhenius behavior which is reminiscent of the slow dynamics in thermal glassy systems. We also investigated the boundary effect on the ordering process and found that boundary rods order faster than interior ones. In searching for the underlying mechanism of the slow dynamics, we estimated the initial random velocities of the rods under tapping and found that the ordering process is compatible with a diffusion mechanism. The average coordination number as a function of the tapping number at different tapping intensities has also been measured, which spans a range from 6 to 8.

Bipartite Polar Classification for Surface Reconstruction

In this paper, we propose bipartite polar classification to augment an input unorganized point set ℘ with two disjoint groups of points distributed around the ambient space of ℘ to assist the task of surface reconstruction. The goal of bipartite polar classification is to obtain a space partitioning of ℘ by assigning pairs of Voronoi poles into two mutually invisible sets lying in the opposite sides of ℘ through direct point set visibility examination. Based on the observation that a pair of Voronoi poles are mutually invisible, spatial classification is accomplished by carving away visible exterior poles with their counterparts simultaneously determined as interior ones. By examining the conflicts of mutual invisibility, holes or boundaries can also be effectively detected, resulting in a hole-aware space carving technique. With the classified poles, the task of surface reconstruction can be facilitated by more robust surface normal estimation with global consistent orientation and off-surface point specification for variational implicit surface reconstruction. We demonstrate the ability of the bipartite polar classification to achieve robust and efficient space carving on unorganized point clouds with holes and complex topology and show its application to surface reconstruction.

Influence of Skew Angle on Continuous Composite Girder Bridge

AbstractThe design of skewed bridges is becoming more customary in the engineering community. In this paper, the effect of the skew angle on continuous composite girder bridges is presented using three-dimensional finite-element analysis. Seventy-two models of two-span bridges with various span ratios (N=1, 1.55, and 1.82), skew angles (0–60°), and various arrangements of intermediate transverse diaphragms are analyzed. All models were subjected to AASHTO HS20-44 loading. Results for skewed bridges are compared with the reference nonskewed bridge, as well as to the AASHTO standard specifications and AASHTO LRFD specifications. The results show that as the skew angle increases, the support moment in interior and exterior girders rapidly decreases. It decreases about 10% when the skew angle is less than 20° and reaches 33% for a 45° skew angle. The shear force increases in the pier support at the exterior girders and decreases at the interior ones with increasing skew angle. For exterior girders, the ratio ...

Non-uniformity correction algorithm for IRFPA based on motion controllable micro-scanning and perimeter diaphragm strips

Non-uniformity correction is the key issue for the image quality improvement of infrared focal panel array (IRFPA) imaging. A non-uniformity correction (NUC) algorithm for IRFPA based on motion controllable micro-scanning platform and perimeter diaphragm strips is presented. We initially execute one-point calibration to the perimeter detectors, then based on controllable motion of adjacent frames, a special algebraic algorithm is proposed to transport the calibration of the perimeter detectors to those interior un-corrected ones. In this way, the bias parameter of the whole field of view (FOV) is calculated. The algorithm can be easily combined with sub-pixel imaging, thereby improving the quality of thermal imaging system (image spatial resolution and uniformity). All calculations are algebraic, with a low computation load. The algorithm can realize adaptive one point calibration without covering the central FOV rapidly. Experiments on simulated infrared data demonstrate that this algorithm requires only dozens of frames to obtain high quality corrections.