Literatura científica selecionada sobre o tema "Curved block structure"

Third order displacement function is introduced into DDA (DDA3O), which can easy to analysis the nonlinear distribution of deformation, stress and strain within a single block. In this paper, additional nodes were inserted on the boundary. So, when large deformation is involved, even the original straightly boundary of block will deform to one formed by curved edges, the simplex integration along the curved edge can increase accuracy and simulation of contact between blocks can be more reasonable. On the other hand，the problem of transferring the initial stress from previous step to next step is difficulty and unresolved problem, because of the strain matrix of high order displacement function involving the unknown variables x, y. A new method presented herein is inherent previous the displacement of block to next step, which is proved right and efficient. At last, some example was calculated to demonstrate the excellent accuracy and efficiency of DDA3O.

The structure of eccentric degenerated 3-D shell element of thin-wall steel tube concrete composite structure and the connection with 3-D block isoparametric element has been discussed using finite element method. Without considering the intensity limit of delamination damage of the two materials, an integrated stiffness matrix is formed with the combination of stiffness matrix of steel-wall shell element and that of concrete spatial block element. In order to make the superposition rule may be used at the joint of 8-node curved shell element and 20-node block element, an eccentric 8-node shell element is constructed.

Thin Open Curved Shell Structures constitute the major building block of many critical structures such as Aircraft Cabins, Ship Hulls and bodies of rockets and missiles. In the present work, an open thin curved shell made of Aluminium material has been chosen to investigate the potential of ACLD effectiveness with MFC Actuator. The shell ACLD system has been modelled using system identification method and converted into state space form for designing the control law of the LQR controller. Finite Element Analysis of the bare structure has been performed in ANSYS. Using modal solution results, the best possible location for the placement of patches has been found out for combined vibration control of first three modes using Modal Strain Energy (MSE) approach. The FEA Modal Solution results have been correlated with the experimental modal analysis results obtained with the help of ICATS (Imperial College’s Modal Analysis and Testing Software). Significant vibration attenuation resulted for partially covered PCLD and ACLD treatments on open curved shell. Thus, ACLD provides a practical means for controlling the vibration of complex structures such as an open curved shell with currently available piezoelectric (MFC) actuators without the need for excessively large actuation voltages.

For the improvement of the deformation characteristic and the energy absorption efficiency of the tubular structure at impact event, a method generating the first buckling lobe using the inertia force was investigated. The solid block was attached to the wall so that its inertia force causes the partial plastic deformation that plays a role of the trigger of progressive buckling at the beginning of impact. Drop-weight impact experiment revealed that the onset of progressive buckling was achieved at the desired portion by the method. To increase the variety of tube shapes, numerical examination was conducted with the dynamic explicit finite element method. Long straight and S-curved tubes, which have square cross-section, were numerically modeled with shell elements. They were assumed to be impacted to the rigid wall to estimate the dynamic collapse behavior. The first buckling lobe generated by inertia force was demonstrated for the straight tube. The S-curved tube exhibited a bending collapse mode without the method. However, such mode was avoidable by applying the method. Then the energy absorption efficiency of the tube was drastically increased.

Background Few studies have examined the use of ultrasound for sciatic nerve localization. The authors evaluated the usefulness of low-frequency ultrasound in identifying the sciatic nerve at three locations in the lower extremity and in guiding needle advancement to target before nerve stimulation. Methods In this prospective observational study, 15 volunteers underwent sciatic nerve examination using a curved ultrasound probe in the range of 2-5 MHz and a Philips-ATL 5000 unit (ATL Ultrasound, Bothell, WA) in the gluteal, infragluteal, and proximal thigh regions. Thereafter, an insulated block needle was advanced inline with the ultrasound beam to reach the nerve target, which was further confirmed by electrical stimulation. The quality of sciatic nerve images, ease of needle to nerve contact, threshold stimulating current, and resultant motor response were recorded. Results The sciatic nerve was successfully identified in the transverse view as a solitary predominantly hyperechoic structure on ultrasound in all of the three regions examined. The target nerve was visualized easily in 87% and localized within two needle attempts in all patients. Nerve stimulation was successful in 100% after two attempts with a threshold current of 0.42 +/- 0.12 (mean +/- SD) eliciting foot plantarflexion or dorsiflexion. Conclusions These preliminary data show that a curved 2- to 5-MHz ultrasound probe provides good quality sciatic nerve imaging in the gluteal, infragluteal, and proximal thigh locations. Ultrasound-assisted sciatic nerve localization is potentially valuable for clinical sciatic nerve blocks.

The paper considers the development and automation of an algorithm for designing a reinforcement scheme based on bending deformation. The algorithm is presented in the form of a block diagram. When searching for a reinforcement trajectory, the algorithm takes into account the specified criteria for searching and designing a scheme. On the basis of the algorithm, a program is developed that can operate with the data of the model under study, use them to construct and synthesize the reinforcement trajectory. The program code is based on a simple example – bending deformation. The stress-strain state (SSS) is analyzed, the deformation proceeds linearly and in one direction. As a result, the reinforcement paths are straight lines. For nonlinear deformation, this code provides a spline function that is used to construct curved trajectories. Automation of the algorithm for designing reinforcement trajectories in the form of a program made it possible to reduce the time of searching, processing and compiling trajectories.

The proposed article is addressed to the phenomenon of typical graphic elements used in Russian late medieval visual art; the study is based on the material of miniatures of the wellknown illuminated manuscript of the Commentated Prophet Book from the collection of the Moscow Theological Academy. Previously, a detailed comparison of the drawing of paper icon samples, and later of the icons themselves of the 15th–16th centuries as well, led to the conclusion that icon painters widely use a set of the same systematically repeating graphic elements. They can always be seen in almost any icon, in different numbers and different combinations, in the most dissimilar images and regardless of who or what is depicted on the icon: the Savior, the Virgin or a prophet; regardless of whether the image in front of us is a half-length image, shoulder-length or full-length figure; regardless of the pose, gestures and type of clothing. Those elements are used constantly, although their number and set may vary significantly from case to case. In addition, their graphics vary quite freely: the proportions within the block and its dimensions change relative to other parts of the image, straight lines may be more or less curved, or part of the block may be hidden by another detail or, on the contrary, shown two or more times. Sometimes some part of the block is inverted, shifted or reduced, but the structure of the block remains the same. This observation makes it possible to significantly clarify the ideas about the principles of icon-painter work in the 15th–17th centuries: the drawing, for example, of a human figure and their robes was not copied literally from icon to icon, neither was invented completely anew each time; the image was more or less “constructed” from already existing ready-made blocks, either in the literal sense, or they filled in a ready-made general compositional scheme or a part of it, which itself can be considered as a standard block of a higher order. The miniatures of the manuscript under study serve as a clear example of the use of standard blocks in the Moscow illuminated book of the 15th century. The article for the first time compares a large number of deesis and prophetic images.

Cutouts are widely used in ships and offshore structures. Cutouts of big size are used mainly for inspection, passing pipes, and weight reduction. Some cutouts of small size may be used for various purposes, such as water hole in the web of stiffeners. The stiffeners with perforated web are the most commonly adopted structure members in the shipbuilding industry, and they are mainly fabricated by cutting and bending the frame to meet the requirements of desired design configuration. In ship production, the manufacture of the curved stiffener with holes is desirable to perforate first and then to bend the frame. This fabrication procedure is adopted for efficient production because of the layout of the production line. However, structural distortion and damage may occur during cold bending of the frames with perforated web, such as necking, wrinkling, and even crack initiation. This problem should be solved in ship production. In this study, cold bending experiments and finite element simulations were performed to analyze the deformation characteristics of curved frames with cutouts. A fabrication method is proposed to control the deformation in the cutouts during the bending process. In this method, the block cut out during the first step is filled in the hole and afterward the frame is bent. The results show that this method can control well the deformation localized around the hole during the bending process. It offers an important guidance for cold bending steel frames in ship production.

We present a computational inverse design framework for a new class of volumetric deployable structures that have compact rest states and deploy into bending-active 3D target surfaces. Umbrella meshes consist of elastic beams, rigid plates, and hinge joints that can be directly printed or assembled in a zero-energy fabrication state. During deployment, as the elastic beams of varying heights rotate from vertical to horizontal configurations, the entire structure transforms from a compact block into a target curved surface. Umbrella Meshes encode both intrinsic and extrinsic curvature of the target surface and in principle are free from the area expansion ratio bounds of past auxetic material systems. We build a reduced physics-based simulation framework to accurately and efficiently model the complex interaction between the elastically deforming components. To determine the mesh topology and optimal shape parameters for approximating a given target surface, we propose an inverse design optimization algorithm initialized with conformal flattening. Our algorithm minimizes the structure's strain energy in its deployed state and optimizes actuation forces so that the final deployed structure is in stable equilibrium close to the desired surface with few or no external constraints. We validate our approach by fabricating a series of physical models at various scales using different manufacturing techniques.

Le Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA) s'intéresse à la simulation d'écoulements fluides en régime supersonique et hypersonique dans le cadre de la rentrée atmosphérique. Pour ce faire, un code de simulation numérique dédié y est développé. Pour répondre à des contraintes fortes, ce code ne prend en entrée que des maillages hexaédriques structurés par blocs. Ce type de maillage est compliqué à générer, c'est le plus souvent réalisé à la main via l'utilisation de logiciels interactifs dédiés. Pour des géométries industrielles complexes, la génération d'un maillage est très couteuse en temps. A l'heure actuelle, la génération automatique de maillages hexaédriques est un sujet de recherche ouvert et complexe.Dans le cadre de ces travaux de thèse, nous proposons une méthode permettant de générer des maillages structurés par blocs courbes de domaines fluides autour de géométries dédiées pour les problématiques visées. Cette méthode a d'abord été prototypée dans le cadre de domaines 2D, puis étendue au cas 3D. Ici, la méthode est présentée dans le cas général, en dimension n. Elle se découpe en plusieurs étapes qui sont les suivantes.Dans un premier temps, une structure de blocs linéaire est obtenue par extrusion d'une première discrétisation de la paroi. Ces travaux sont une extension des travaux proposés par Ruiz-Girones et al.. Une fois cette structure de blocs linéaire obtenue, nous proposons deux manières distinctes de courber les blocs afin d'améliorer la représentation de la géométrie, et de limiter le lissage sur le maillage final. La première est à travers d'un processus de lissage de maillage à topologie fixe à l'aide d'un problème d'optimisation, auquel un terme de pénalité est ajouté pour aligner certaines arêtes du maillage aux interfaces. Dans notre processus, nous appliquons cette méthode de lissage à la structure de blocs pour l'aligner sur la surface du véhicule. Cette méthode étant pour l'instant trop couteuse en temps de calcul dans le cas 3D, nous proposons une seconde manière de courber les blocs, à travers une représentation à l'aide de courbes polynomiales de Béziers. Nous appliquons cette fois des opérations géométriques et locales afin d'aligner les blocs à la géométrie.Enfin, en partant du principe que les blocs sont représentés à l'aide de courbes de Bézier, nous générons un maillage final sur ces blocs courbes sous différentes contraintes. Finalement, nous évaluons la qualité des maillages générés à travers des critères purement géométriques, en étudiant l'impact des différents paramètres de notre méthode sur le maillage final. Nous évaluons également les maillages générés par la simulation d'écoulements fluides sur ces maillages, avec la comparaison à des données expérimentales, analytiques, ainsi qu'à des calculs de référence
The French Alternative Energies and Atomic Energy Commission (CEA) studies Computational Fluid Dynamics (CFD) in the case of supersonic and hypersonic flows. To do so, a dedicated code is developed. To deal with strong constraints, this code only performs on block-structured meshes. This specific type of mesh is complicated to generate, and this generation is usually handled by hand using dedicated interactive software. In the case of industrial complex geometries, the mesh generation is highly time-consuming. Currently, automatic hexahedral mesh generation is a complex open research field.In this thesis work, we propose a method to generate block-structured hexahedral meshes on curved blocks of the fluid domain around vehicles, dedicated for the problems of interest. This method is first proposed in 2D and then extended to 3D. Here, it is presented in the generic nD case. This method is composed of several steps. First, a linear block structure is extruded from a first vehicle surface discretization. This work is an extension of the previous work of Ruiz-Girones et al.. Once this linear block structure is generated, we propose two different methods to curve the block structure to improve the vehicle surface representation and limit the smoothing on the final mesh. The first method is through an algorithm of mesh adaptation at fixed topology by solving an optimization problem to which a penalty term is added to align certain mesh edges to an implicit interface. Our global approach uses this method to align the block structure to the vehicle surface. This method remains time-consuming in 3D, so we proposed a second method to curve our block structure through polynomial Bézier curves. Considering our blocks as Bézier blocks, we apply geometric and local operations to align the high-order block structure to the vehicle surface. Then, considering we curved the block structure using Bézier elements, we generate a mesh on the curved blocks under constraints. Finally, the generated mesh quality is evaluated in two ways. The first one is through purely geometrical criteria analysis. The second one is through numerical simulations of flows around vehicles on our meshes, comparing the simulation results to experimental data, analytical results, and reference simulations

We study a free quantum scalar field in the BTZ spacetime as a model of the AdS/CFT correspondence for black holes, and show the essential steps in computing Bogolyubov coefficients between modes on either side of the wormhole. As background, we review the BTZ geometry in standard, Kruskal and Poincaré coordinates, holographic renormalisation of the dual field theory and canonical quantisation in curved spacetime.
Vi studerar ett fritt skalärt kvantfält i BTZ-rumtiden som en modell av AdS/CFT-dualiteten för svarta hål och visar huvudstegen i beräkningen av Bogolyubov-koefficienter mellan moder på olika sidor av maskhålet. Som bakgrund redogör vi för BTZ-geometrin i standard-, Kruskal- och Poincarékoordinater, holografisk renormering av den duala fältteorin och kanonisk kvantisering i krökt rumtid.

In this master thesis, we compare three different types of funding alternatives from a Swedish municipality's point of view, with the main focus on analysing a Nikkei-linked loan. We do this by analysing the resulting interest rate and the expected exposures, taking collateral into consideration. We conclude, with certainty, that there are many alternatives for funding and that they each need to be analysed and compared on many levels to be able to make a correct decision as to which ones to choose. An important part of this is to consider the implications of the newest regulations and risk exposure, as it might greatly influence the final price for contracts. Between the cases that we considered, the SEK bond was the one with the lowest resulting spread, and the one which is the simplest considering the collateral involved. While other alternatives might be better depending on how profitable it is for the municipality to receive collateral, the SEK bond is the most transparent one and with least risk involved.

Els forats negres acústics en mecànica (coneguts per les sigles ABHs, de l’anglès Acoustic Black Holes) solen estar formats per osques en bigues i plaques, el gruix de les quals decau segons una llei potencial. L’efecte de l’ABH és el d’alentir les velocitats de fase i de grup de les ones de flexió incidents de tal manera que, en teoria, faria falta un temps infinit perquè les ones arribessin al centre de l’ABH, si el gruix d’aquest últim fos exactament zero. Tanmateix, a la pràctica això no és possible tot i que es pot aconseguir una forta dissipació col·locant una capa de material esmorteïdor al centre de l’ABH, on es concentra la major part de l’energia de les ones. En els darrers anys, els ABHs no només s’han explotat com a mètode passiu per reduir vibracions estructurals i l’emissió corresponent de soroll, sinó que també s’ha explorat el seu potencial per altres aplicacions com la manipulació d’ones o la captació d’energia. Aquesta tesi té tres objectius principals. Així, doncs, després d'una introducció general als ABHs, el treball s’ha dividit en tres grans seccions. La primera aborda aplicacions dels ABHs en bigues rectes i plaques planes. Per començar, es proposa i s’analitza un voladís piezoelèctric amb un acabament d’ABH per capturar energia. A continuació es presenten ABHs en forma d’anell per tal d’aïllar punts d’excitació externs en plaques planes i així evitar la transmissió de vibracions. Finalment, es contemplen configuracions periòdiques de matrius d’ABHs per tal de col·limar feixos d'ones de flexió i concentrar la seva energia en zones predeterminades d’una placa. La segona part de la tesi proposa nous dissenys d’ABHs per a estructures amb curvatura. Aquestes són molt habituals en els sectors naval, aeronàutic i industrial, de manera que val la pena investigar si els ABH poden resultar alguns casos. La secció comença analitzant la inclusió d’ABHs en bigues circulars i es veu com això dona peu a l’aparició de fenòmens típics en sistemes periòdics. Acte seguit es proposa un ABH anular per reduir les vibracions en conductes cilíndrics. En concret, es tracten els casos d’un conducte simplement suportat amb un ABH anular, i el d’un conducte amb ABH, suports periòdics i rigidificadors. Per finalitzar la secció, s’investiguen els efectes dels ABH anulars en la radiació acústica del conducte tenint en compte el nivell de potència acústica, l’eficiència de radiació i la intensitat supersònica. La tercera part de la tesi és més curta que les anteriors i simula l’aïllament d'una placa amb múltiples ABHs, en el rang de mitja i alta freqüència. A tal efecte s’empra el mètode de l’anàlisi estadística de distribució modal d'energia (SmEdA: statistical modal energy distribution analysis). En aquesta secció, l’estructura amb ABHs ja no s’analitza com un element individual sinó que s’acobla a dues cavitats d’aire, formant part d’un sistema mecànic més complex. Al llarg de la tesi s’utilitza repetidament el mètode d’expansió gaussiana (GEM: Gaussian expansion method). Pel GEM entenem prendre funcions gaussianes com a base per resoldre equacions diferencials en derivades parcials en el marc del mètode de Rayleigh-Ritz. El GEM s’assembla molt als enfocaments d’ondetes, però ofereix alguns avantatges en el cas de condicions de contorn periòdiques. Al principi de la tesi s’exposa un breu repàs del GEM i, quan és necessari, s’aborda la seva reformulació per a un problema particular en el capítol corresponent.
Los agujeros negros acústicos en mecánica (conocidos por las siglas ABHs, del inglés Acoustic Black Holes) suelen estar formados por muescas en vigas y placas, el grueso de las cuales decae según una ley potencial. El efecto del ABH es el de ralentizar las velocidades de fase y de grupo de las ondas de flexión incidentes de tal modo que, en teoría, haría falta un tiempo infinito para que las ondas alcanzaran el centro del ABH, si el grueso de este último fuera exactamente cero. Sin embargo, en la práctica esto no es posible, aunque se puede conseguir una fuerte disipación colocando una capa de material amortiguador en el centro del ABH, donde se concentra la mayor parte de la energía de las ondas. En los últimos años, los ABHs no sólo se han explotado como método pasivo para reducir vibraciones estructurales y la consecuente emisión de ruido, sino que también se ha explorado su potencial para otras aplicaciones como la manipulación de ondas o la captación de energía. Esta tesis tiene tres objetivos principales. Así pues, tras una introducción general a los ABHs, el trabajo se ha dividido en tres grandes secciones. La primera aborda aplicaciones de los ABHs en vigas rectas y placas planas. Para empezar, se propone y analiza un voladizo piezoeléctrico con un acabado de ABH para capturar energía. A continuación, se presentan ABHs en forma de anillo para aislar puntos de excitación externos en placas planas y así evitar la transmisión de vibraciones. Finalmente, se contemplan configuraciones periódicas de matrices de ABHs para colimar haces de ondas de flexión y concentrar su energía en zonas predeterminadas de una placa. La segunda parte de la tesis propone nuevos diseños de ABHs para estructuras con curvatura. Estas son muy habituales en los sectores naval, aeronáutico e industrial, por lo que merece la pena investigar si los ABH pueden dar buenos resultados en algunos casos. La sección comienza analizando la inclusión de ABHs en vigas circulares y se ve como estos dan pie a la aparición de fenómenos típicos de sistemas periódicos. Seguidamente se propone un ABH anular para reducir las vibraciones en conductos cilíndricos. En concreto, se tratan los casos de un conducto simplemente soportado con un ABH anular, y el de un conducto con ABH, soportes periódicos y rigidificadores. Para finalizar la sección, se investigan los efectos de los ABH anulares en la radiación acústica del conducto teniendo en cuenta el nivel de potencia acústica, la eficiencia de radiación y la intensidad supersónica. La tercera parte de la tesis es más corta que las anteriores y simula el aislamiento de una placa con múltiples ABHs, en el rango de media y alta frecuencia. A tal efecto se emplea el método del análisis estadístico de distribución modal de energía (SmEdA: statistical modal energy distribution analysis). En esta sección, la estructura con ABHs ya no se analiza como un elemento individual, sino que se acopla a dos cavidades de aire formando parte de un sistema mecánico más complejo. A lo largo de la tesis se utiliza repetidamente el método de expansión gaussiana (GEM: Gaussian expansión method). Por GEM entendemos tomar funciones gaussianas como base para resolver ecuaciones diferenciales en derivadas parciales en el marco del método de Rayleigh-Ritz. El GEM se parece mucho a los enfoques de ondículas, pero ofrece algunas ventajas en el caso de condiciones de contorno periódicas. Al principio de la tesis se expone un breve repaso del GEM y, cuando es necesario, se aborda su reformulación para un problema particular en el capítulo correspondiente.
Acoustic black holes (ABHs) in mechanics usually consist of geometrical indentations on beams and plates having a power-law decreasing thickness profile. An ABH slows down the phase and group velocity of incident flexural waves in such a way that, ideally, it would take an infinite amount of time for them to reach the ABH center, if the latter had an exact zero thickness. Though this is not possible in practice, strong wave dissipation can be achieved by placing a damping layer at the central region of the ABH, where most vibration energy concentrates. In recent years, ABHs have been not only exploited as a passive means for structural vibration and noise reduction, but its potential for other applications like wave manipulation or energy harvesting have been also explored. The objective of this thesis is threefold. Therefore, after an initial overview the work is divided into three main parts. The first one deals with ABH applications on straight beams and flat plates. To start with, an ABH piezoelectric bimorph cantilever for energy harvesting is proposed and analyzed. Then, ring-shaped ABH indentations are suggested as a means of isolating external excitation points in flat plates and prevent vibration transmission. Finally, periodic ABH array configurations are contemplated to collimate flexural wave beams and focus energy at desired plate locations. The second part of the thesis proposes new ABH designs for curved structures. The latter are very common in the naval, aeronautical and industrial sectors so it is worth investigating if ABHs could function for them. The section starts analyzing the embedding of ABHs on circular beams and how this results in the appearance of typical phenomena of periodic systems. After that, an annular ABH is proposed to reduce vibrations in cylindrical shells. The cases of a simply supported shell with an annular ABH indentation and of a periodic simply supported ABH shell with stiffeners are considered. To finish the section, the effects of annular ABHs on sound radiation are investigated in terms of sound power level, radiation efficiency and supersonic intensity. The third part of the thesis is shorter than the previous ones and is devoted to analyzing the transmission loss of a plate with multiple ABH indentations, in the mid-high frequency range. Statistical modal energy distribution analysis is used for that purpose. Here, the ABH plate is not taken as an individual structure but coupled to two air cavities, thus being part of a more complex mechanical system. Throughout the thesis repeated use is made of the Gaussian expansion method (GEM). The GEM refers to taking Gaussian functions as the basis for solving partial differential equations in the framework of the Rayleigh-Ritz method. The GEM closely resembles wavelet approaches but offers some advantages in the case of periodic boundary conditions. A brief overview of the GEM is exposed at the beginning of the thesis and, when necessary, its reformulation for a particular problem is tackled in its corresponding chapter.

This work investigates the correlation of structural and photovoltaic properties of dyes used in dye-sensitized solar cells. Experimental methods, including ultraviolet-visible spectroscopy, fluorescence spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy are employed to study optical and electrochemical properties of dye molecules. Computational methods, including density functional theory and time-dependent density functional theory, are used to validate and predict the optical and electronic properties of dye molecules, in their isolated state and once embedded into a working electrode device environment that comprises a dye...TiO2 interface. The results chapters begin with the presentation of a series of quinodimethene dyes that are experimentally validated for their photovoltaic application, and associated computational studies reveal that an inner structural factor - a phenyl ring rotation occurring during the optical excitation process - leads to the competitive photovoltaic device performance of these dyes. Carbazole-based dyes are then systematically studied by computation, especially considering charge transfer paths and binding modes of these dyes on a titania surface. The theoretical models for the basic building block of this chemical family of dyes, known as MK-44, successfully support and explain structural discoveries from X-ray diffraction and reflectometry that impact of their function. A benzothiadiazole-based dye, RK-1, is then systematically studied by both experimental and computational methods, and the results show that the π-bridge composed of thiophene, benzothiadiazole and benzene rings leads to excellent charge separation; and the rotation of these rings during the optical excitation process may well be consistent with the fluorescence spectrum. Finally, the well-known ruthenium-based dyes are theoretically studied to determine the properties of different ligands connected to the metal core of the complex. Conformations with different NCS ligands are calculated in terms of energy and explain well the corresponding results from X-ray diffraction. Acid-base properties of carboxyl groups connected to pyridine ligands in N3 and N749 are theoretically calculated based on thermodynamics and density functional theory. Implicit and explicit models are both adopted to predict these acid dissociative constant values, which are generally in a good agreement with the reported experimental data. The thesis concludes with conclusions and a future outlook.

A high-order central essentially non-oscillatory (CENO) finite-volume scheme in combination with a block-based adaptive mesh refinement (AMR) algorithm is proposed for solution of hyperbolic and elliptic systems of conservation laws on body- fitted multi-block mesh. The spatial discretization of the hyperbolic (inviscid) terms is based on a hybrid solution reconstruction procedure that combines an unlimited high-order k-exact least-squares reconstruction technique following from a fixed central stencil with a monotonicity preserving limited piecewise linear reconstruction algorithm. The limited reconstruction is applied to computational cells with under-resolved solution content and the unlimited k-exact reconstruction procedure is used for cells in which the solution is fully resolved. Switching in the hybrid procedure is determined by a solution smoothness indicator. The hybrid approach avoids the complexity associated with other ENO schemes that require reconstruction on multiple stencils and therefore, would seem very well suited for extension to unstructured meshes. The high-order elliptic (viscous) fluxes are computed based on a k-order accurate average gradient derived from a (k+1)-order accurate reconstruction. A novel h-refinement criterion based on the solution smoothness indicator is used to direct the steady and unsteady refinement of the AMR mesh. The predictive capabilities of the proposed high-order AMR scheme are demonstrated for the Euler and Navier-Stokes equations governing two-dimensional compressible gaseous flows as well as for advection-diffusion problems characterized by the full range of Peclet numbers, Pe. The ability of the scheme to accurately represent solutions with smooth extrema and yet robustly handle under-resolved and/or non-smooth solution content (i.e., shocks and other discontinuities) is shown for a range of problems. Moreover, the ability to perform mesh refinement in regions of smooth but under-resolved and/or non-smooth solution content to achieve the desired resolution is also demonstrated.

Black Matrilineage, Photography, and Representation questions how the Black female body, specifically the Black maternal body, navigates interlocking structures that place a false narrative on her body and that of her maternal ancestors. Drawing on a wide range of scholarly inquiry and contemporary art, this book addresses these misconceptions and fills in the gaps that exist in the photographic representation of Black motherhood, mothering, and mutual care within Black communities. The essays and interviews, paired with a curated selection of images, address the complicated relationship between Blackness and photography and in particular its gendered dimension, its relationship to health, sexuality, and digital culture – primarily in the context of racialized heteronormativity. This collection, then, challenges racist images and discourses, both historically and in its persistence in contemporary society, while reclaiming the innate brilliance of Black women through personal stories, history, political acts, connections to place, moments of pleasure, and communal celebration. This visual exploration of Black motherhood through pictures made by Black woman–identifying photographers thus serves as a reflection of the past and a portal to the future and contributes to recent scholarship on the complexity of Black life and Black joy.

Megaprojects are large and are constantly growing ever larger, and more and more are being built in what has been called the biggest investment boom in history. This chapter serves as an introduction to megaprojects in which they are defined and in which the size of global megaprojects business is estimated. Drivers of the megaproject boom are identified, including monumentalism and the technological sublime; ten things you must know about megaprojects are detailed, from their tendency to suffer from uniqueness bias to their overexposure to black-swan events; and the “iron law of megaprojects” is identified as a main challenge to megaproject management: “Over budget, over time, under benefits, over and over again.” Finally, the main structure of the Handbook is set out as covering the what, the why, and the how of megaproject management, in terms of the challenges, causes, and cures that students of megaprojects must decipher to better understand and better manage them.

The relevant provisions of the mortar rebound method in the national code GB/T50315 “Technical Standards for site testing of masonry engineering” is only focus on mortar rebound method of sinter bricks, but whether the rebound curve of sintered brick mortar can be used for non-sintered brick mortar is uncertain. Therefore, the rebound curve of non-sintered brick mortar needs to be further studied. The mortar rebound method of sintered bricks is used as a model for the research process for mortar rebound method of other blocks, and the mortar of three widely used blocks of concrete products in masonry structures is selected as the research object. In the end, the mortar rebound curves for mortars of three widely used blocks are obtained through relevant tests, the results showed that the mortar rebound curves of sintered brick and non-sintered brick are completely different, thus broadening the application area of the mortar rebound method.

This work specifically examines the analysis of building blocks structures that experience finite displacements. The analysis was conducted with incremental sequential techniques. The Newton-Raphson iteration approach is used to load structural stages that have the ability to either soften or harden. A modified Newton-Raphson iteration technique is employed for loading stages in which the determinant of the global stiffness matrix is near 0 or negative, as observed in the snap-through scenario. The advanced computer language Fortran is used for structural analysis. To ensure the program's integrity, SAP (structural analysis program) is used for verification. The software is then used in several structural systems case studies. To accomplish this, the authors compare the axial stiffness of panels and jack elements as well as the height-to-span ratios of various structures. The structural responses were modelled using stiffening, snap-through, and softening load-displacement curves.

Based on the measured irregularity data of Shanghai rail transit 11# line, firstly from the angle of time domain the amplitude stability and amplitude distribution characteristics of the rail surface short wave irregularity whose wavelengths are in the range of 0.01 ∼ 1 m are analyzed. Secondly from the point of view of frequency domain by using the maximum entropy spectrum method the short wave power spectral density is estimated. Then the power spectral density curves are compared with the short spectrum of Wang Lan and Sato and the different track structure effects on the states of the rail surface irregularities are also analyzed. The research show that the amplitude distribution of track surface short wave irregularity is close to the normal distribution. And the maximum amplitudes of some sections in Jiading Xincheng – Malu and Nanxiang – Taopu saemaul undong exceed 2.0mm. In the section of Liziyuan-Shanghai West Railway Station, the power spectral density curves of track structure with the supporting block, DTIII-2 type fasteners and with the conventional integral track bed are also similar to that of Sato spectrum. And it is obviously superior to that of other track structures in this section.

Nowadays, acoustic black holes (ABHs) are very popular for producing efficient vibration reduction at high frequencies in combination with some damping mechanisms. However, its low-frequency performance is hard to improve since the ABH effect principally occurs beyond its cut-on frequency. Fortunately, periodic ABH configuration offers some bandgaps below that frequency for wave attenuation. In this chapter, a topological ABH structure is suggested to produce a new bandgap at very low frequencies, by taking a supercell and decreasing the ABH distance. The wave and Rayleigh-Ritz method (WRRM) is adopted to compute the complex dispersion curves. Examinations of the dispersion curves and transmissibilities confirm the efficiency of the low-frequency vibration reduction capability of the proposed topological ABHs.

Self-assembly is a process in which structural motives provide specific interaction for directed aggregation of the modular building blocks under equilibrium conditions. Interactions among the building blocks but also between building blocks and solvent play a role. This allows the formation of oriented unimolecular layers and bilayers, such as soap films or biological cell membranes. Depending on the shape of the units, oriented packing may lead to curvature. The interface of the layer to the solvent is associated with a small interfacial energy, and curved surfaces separate regimes of different pressure. In isotropic systems this leads to structures of constant curvature. Nature makes extensive use of these construction principles, and chemists can take advantage of them in biomimetic synthesis in the laboratory. The building motives are often elongated or polar organic molecules such as surfactants, but in liquid crystals the mesogenes can also be disc-shaped. The resulting soft matter structures can be used as moulds for the synthesis of quite artistic architectures from hard ceramics at or near room temperature via the sol–gel process. Alternatively, three-dimensional structures can be designed and synthesised from modules with specific coupling elements. Metal–organic frameworks are examples of such structures which after removal of the solvent are porous and may be stable, suitable for gas adsorption or separation, or catalysis.

Acoustic black holes (ABHs) achieved by progressively diminishing structural thickness have been proved a very efficient approach for wideband vibration reduction, sound suppression, energy harvesting, and wave manipulation. In this chapter, the focus is placed on mitigating the sound emitted from cylindrical shells with embedded ABHs. In the applications of aeronautics, astronautics, and underwater vehicles, cylindrical shells are very common yet the vibroacoustic problems in such structures are very challenging. Even the researches on ABHs for straight beams and flat plates are boosting in recent years, the ABH effect is unclear for curved structures thus it deserves further investigations to push forward their applications. Since cylindrical shells are usually long in, for example, airplanes and rockets, periodic ABHs are designed to alleviate the acoustic emission from them. The Gaussian expansion method (GEM) is employed to recover the vibration field on the cylinder and, based on that, the sound radiation model is developed to determine the emitted sound power level (SWL). The band gaps (BGs) are shown for infinite periodic ABH shells, followed by the vibroacoustic level for a finite periodic shell. Particularly, axial stiffeners are introduced and the influences of their quantity and width are carried out.

In Chapter 2, I examine how violent histories are recounted through the lens of group identity formation in exhibitions. I discuss how relying on the conventions of collective storytelling—the rules and norms around both plot and structure—blunts the sharp edges of history. This chapter analyzes the visual and discursive turns used to construct a metanarrative of group identity forged through collective trauma. In South Africa, this collective experience is articulated as a national one, whereas in the United States interrogation of the society’s racist past is the purview of so-called ethnic or black museums.

<p>This paper is based on the design concept of the block is not damaged under small earthquakes and can be used sustainably and in the medium earthquake does not fall, convenient structure replacement and it can be destroyed during a large earthquake, sacrificing itself to protect the main beam. Based on the characteristics of graded energy dissipation and the advantages of negative Poisson's ratio compared with traditional structures in energy absorption and impact resistance, an anti-seismic energy dissipation bridge block was designed. The mechanical properties of the block were studied by uniaxial loading test and finite element simulation. Through the comparative analysis of normalized curves, it is found that the block structure has a good limiting ability compared with other types of blocks, which can be multi-enhanced stiffness characteristics and excellent bearing capacity.</p>

<p>As a new type of structural system, hybrid masonry (HM) structure with reinforced concrete (RC) frame is constructed of reinforced block masonry wall and reinforced concrete frame. This structural system combines the advantages of reinforced concrete frame structure and reinforced concrete block masonry structure, also overcomes some limitations of them. In order to study the seismic performance of the structural system, the lateral reversed cyclic loading experiment on the HM structure with RC frame was conducted. In the experiment, two specimens that were constructed with different connecting type were designed and tested, in one of them the masonry blocks was separated from the RC frame and only connected with steel keys at the top part of the specimen, while in the other there was no spacing between the RC frame and the masonry blocks. According to the data of the experiment, the paper analyzed the failure process and patterns, hysteretic characteristic, skeleton curve, stiffness degradation and displacement ductility of the structural system, and compared the results of the two specimens. The experimental study indicated that the HM structure with RC frame showed extraordinary good seismic performance during testing, and this form of construction had fairly good displacement ductility and energy dissipation, which would provide a basis for further theoretical analysis and design method.</p>

This paper presents results of vibration tests conducted on a recently reconstructed suspension bridge in Ostrožac, Bosnia and Herzegovina. The Ostrožac bridge spans 200 m over the Jablanica Lake and represents a case of exceptional engineering. However, it is also a typical example of ageing infrastructure characterized by a lack of adequate maintenance and severe degradation by corrosion. The main girders are a complex steel portable Bailey-type trusses suspended by Ø30 mm steel hangers and 6Ø52 mm primary load-bearing cables. The curved cables support the road pass over 18 m high reinforced concrete pylons. Six 44 m long straight inclined back-stay cables transfer the tensile force using threaded rods to the reinforced concrete block anchorages at both ends. The dynamic parameters were obtained by on-site measurements using Digitex xWave triaxial accelerometers and the output-only operational modal analysis which does not require knowledge of the input excitation. The vibrations were induced by wind and by the passage of cars. The structure vibrates spatially even though the nature of excitation is dominantly vertical and the adjacent structural segments of the Bailey truss oscillate almost independently. Power spectrum, damping and Scruton number were determined from acceleration and displacement measurements of the inclined cables. Natural frequency was employed for estimation of the cable axial force. Even though the inclined cables have solid dynamic parameters, notable wind-induced vibrations were visually detected implying the need for structural strengthening intervention.

Integrating passive components on package is getting more and more attractive. To speed up the lumped-elements-based RF functional blocks, like filters, matching networks and so on, fast synthesis of these lumped elements is necessary. Traditional synthesis method like try-error-try again is not only time consuming but also hard to find an optimal one. This is especially true for spiral inductor design due to many tunable parameters. Design based on library has also some disadvantages, such as lack of information of manufacture tolerances’ impact. This paper describes an optimal synthesis method based on curve fitted formula. Full wave electromagnetic simulator is first used to model a set of typical structures. Curve fitting technique is then used to express capacitance, inductance, Q-factor, SRF as functions of geometric parameters and frequency, which is then integrated in a software tool for package inductor and capacitor design. With these fitted curves, manufacture tolerance analysis becomes very easier, and one can easily find the optimal design for the real application, therefore speeds up the function block design.

Abstract One facet of sustainable manufacturing is minimizing material usage and waste. This is done by creating latticelike infills for components, i.e. mesostructures. The goal of this study was to quantify the compression energy absorbed by a stereolithographic (SLA) manufactured mesostructure. Fifteen specimens were printed using a Form 2 SLA printer from Formlab. After printing, the specimens were washed in isopropyl alcohol to remove any uncured resin. The specimens were printed as 80 × 80 × 20 mm blocks for compression testing. The structure of the block was a novel, open-source mesostructure designed by Andreas Bastian. The specimens were compressed in a Tinius Olsen compression testing machine. Using Matlab, these compression curves were numerically integrated to obtain energy absorbed as a function of relative displacement. The SLA structures absorbed 0.5–10.9 Joules at 40% relative displacement. As modulus of the base SLA material increased, so did the energy absorbed by the structure (r = 0.867, p &lt; 0.001). This indicates the compression behavior SLA structures may be predicted through modeling to fine tune the structure. This fine tuning could then be used to maximize the energy absorption of the structure for a desired application, e.g. football helmet cushioning.

Abstract Film cooling technique is commonly adopted in modern gas turbine engines to protect high-temperature components from erosion and damage caused by thermal stress. To improve film cooling effectiveness, many efficient prediction tools have been developed and have shown promising results, which are helpful for turbine aero-thermal design. For film cooling, evidence has shown that it is strongly affected by the momentum and heat transport in the boundary layer when hot gas and coolant are mixed downstream of the ejection. From the view of resolution accuracy in the boundary layer, structured grids will be the primary choice in fluid domain. However, the high-pressure gas turbine blades usually have several hundreds of cooling holes with different configurations and arrangements. Numerical simulations often face a big challenge in multi-block structured-grid generations when a large number of cooling holes are involved on curved hole-to-mainstream interfaces. Conventional block-splitting and mesh-generation for all holes are quite time-consuming and cumbersome, because the copying, translating and rotating manipulations cannot be applied on curved hole-to-mainstream interfaces directly. To solve these difficulties, this paper presents a novel mesh-generation strategy, which is a background-grid based mapping (BGBM) method, to generate multi-block structured grids for film-cooled blade efficiently without modifying the existing meshing tools and solvers, which is convenient for CFD users. It consists of three main steps: At first, the correspondence between physical space and computational space is established by two sets of background grids. Then, the sectional curves of geometry features in physical space are projected to the computational space. With these treatments, the curved hole-to-mainstream interfaces are flattened in computational space, where grids can be quickly generated with block copying, translating, rotating and merging manipulations. Thereafter, meshes in computational space are mapped back to the physical space based on the correspondence between physical and computational spaces, and high-quality structured-meshes can be obtained for numerical simulations. To demonstrate the presented meshing strategy, several typical cases with film cooling are selected for testing, including single cooling hole on curved surface, multiple rows of cooling holes on curved surface and NASA C3X vane with multiple hole arrays. In these cases, different holes, including the cylindrical holes and shaped holes with different ejection angles and arrangements, on curved interfaces are taken into consideration. The quality of generated structured grids for each test case is illustrated, which is able to meet the requirement of CFD solver. With the generated meshes, conjugate heat transfer performance in the turbine vane with different cooling arrangements is investigated and also validated with the existing experimental data.

New reforms have been adopted in banking system of Uzbekistan since 2017 as monetary policy framework directed from monetary targeting to inflation targeting (IT). Liberalization of the national currency, reaching 5% inflation target on medium-term and operational independence of the Central Bank of Uzbekistan (CBU) have started progress of the reforms. The CBU has set policy rate as the primary tool of monetary policy in the context of inflation targeting regime. According to the experience of countries that implemented inflation targeting regime successfully, it is recommended to use the NewKeynesian semi-structural macroeconomic forecasting model to achieve price stability with the help of policy rate. This paper analyses efficiency of monetary policy by proposing to use NewKeynesian semi-structural macroeconomic forecasting model for Uzbekistan. The model includes 4 main blocks: Demand block (Output gap), Supply block (Philips curve), Exchange rate block (Uncovered Interest Rate Parity (UIP)), Interest rate block (Taylor rule). We expect that this model helps to forecast medium-term macroeconomic scenarios especially reaching inflation target and steady state of the economy.

Abstract A method based on non-uniform rational B-spline (NURBS) curve, surface, and solid technology is presented for interactive grid generation of three-dimensional flow fields encountered in turbomachinery applications. The method allows construction of several types of multi-block grids including H-, O-, and C-grids for two-dimensional grids, and strict H-grids for three-dimensional grid generation. Automated two-dimensional block construction is facilitated via a traversal method that searches four-sided regions in the initial block structure. A NURBS surface is then constructed on each block by transfinite interpolation of the boundary curves themselves, and various point distribution options may be applied. Three-dimensional grid generation is an extension of the two-dimensional procedure. Tri-parametric hyperpatches (NURBS solids) are constructed from the two-dimensional block surfaces and grids may be generated via several point distribution functions. This method exploits existing geometric design data via Initial Graphics Exchange Specification (IGES) input of NURBS-based component geometry. It provides an efficient and robust method for complex grid generation to support a variety of analysis functions. Several example applications are presented to demonstrate the capabilities of the technique.

Support structure deflection distorts bearing rings, redistributes loads over bearing balls, and affects bearing life. In this study, solid finite elements modeled a shaft, bearing inner ring, outer ring, and pillow block. A nonlinear spring element represented each of the bearing balls. The force-versus-deflection curve of the spring element modeled the variable stiffness of the ball/raceway Hertzian contact. The curve also incorporated the diametrical clearance of the bearing to determine if each ball contacted the raceways. Further modification of the curve compensated for the compliance of the nodes of solid elements that modeled raceways. This construct avoided computationally expensive surface-to-surface contact calculations. Program output included deflection of the pillow block and a listing of spring element forces, which characterized the ball loads. The maximum ball load decreased for a bearing installed in a pillow block, and life increased. Material or geometric changes that reduced pillow block stiffness further improved life.

Delta Mahakam is a giant hydrocarbon block which is comprised two oil fields and five gas fields. The giant block has been considered mature after production for more than 40 years. More than 2,000 wells have been drilled to optimize hydrocarbon recovery. From those wells, a huge amount of production data is available and documented in a well-structured manner. Gaining insight from this data is highly beneficial to understand fields behavior and their characteristics. The fields production characterization is analyzed with Production Type-Curve method. In this case, type curves were generated from production data ratio such as CGR, WGR and GOR to field recovery factor. Type curve is considered as a simple approach to find patterns and capture a helicopter view from a huge volume of production data. Utilization of business intelligence enables efficient data gathering from different data sources, data preparation and data visualization through dashboards. Each dashboard provides a different perspective which consists of field view, zone view, sector view and POD view. Dashboards allow users to perform comprehensive analysis in describing production behavior. Production type-curve analysis through dashboards show that fields in the Mahakam Delta can be grouped based on their production behavior and effectively provide global field understanding Discovery of production key information from proposed methods can be used as reference for prospective and existing fields development in the Mahakam Delta. This paper demonstrates an example of production type-curve as a simple yet efficient method in characterizing field production behaviors which is realized by a Business Intelligent application

In light of widespread evidence of parameter instability in macroeconomic models, many time-varying parameter (TVP) models have been proposed. This paper proposes a nonparametric TVP-VAR model using Bayesian additive regression trees (BART). The novelty of this model stems from the fact that the law of motion driving the parameters is treated nonparametrically. This leads to great flexibility in the nature and extent of parameter change, both in the conditional mean and in the conditional variance. In contrast to other nonparametric and machine learning methods that are black box, inference using our model is straightforward because, in treating the parameters rather than the variables nonparametrically, the model remains conditionally linear in the mean. Parsimony is achieved through adopting nonparametric factor structures and use of shrinkage priors. In an application to US macroeconomic data, we illustrate the use of our model in tracking both the evolving nature of the Phillips curve and how the effects of business cycle shocks on inflationary measures vary nonlinearly with movements in uncertainty.

In road mitigation systems characterized by multiple wildlife crossing structures (CS) and multiple-focal species, these species-specific design criteria are important to meeting management goals. CS types and locations are fixed in place and cannot be manipulated experimentally; long term studies may offer the best chance to inform evidence-based designs for new CS projects in the future. Long-term data from Banff National Park are uniquely posed to answer these critical questions. More recently, highway mitigation along US93 in Montana provides an additional case study with which to understand the responses of large animals to different CS designs. The purpose of this study is to identify factors affecting movement of large mammals through CS using data sets from both mitigation projects. Year-round monitoring of CS use was used in an analytical framework to address questions regarding species-specific and community level use of CS; design and habitat factors that best explain species-specific variation; and whether importance of design parameters changes over time. Over the 17 years of the Banff study, and the six years of the Montana study, CS facilitated over 200,000 crossing events at 55 locations. There were significant changes in annual crossing events over time. Variables associated with CS passage rates were species specific, but aligned with a few clusters of preference. With the exception of coyotes, all large carnivore species preferred open span bridges or overpasses to other CS types. In Montana, fencing was positively associated with passage rates for black bears and cougars. We found that wider CS tend to be preferred by most species, irrespective of their location. We also found that wider CS tend to have shorter ‘adaptation’ curves than narrower ones for grizzly bears, coyotes, cougars, and moose. Depending on the heterogeneity of the landscape near the highway, more CS may not create more crossing opportunities if local habitat conditions do not favor animals’ access to the road. At the scale of ecological communities, the flows of mass and energy are likely enough to alter the distribution of ecological processes in the Banff and Montana ecosystems. Our results highlight the value of long-term monitoring for assessing the effectiveness of mitigation measures. Our work confirms the species-specific nature of measure CS performance, leading to our primary recommendation that a diversity of CS designs be considered an essential part of a well-designed mitigation system for the large mammals of western North America. Short-term monitoring efforts may fail to accurately portray the ecological benefits of mitigation for populations and ecological communities. Our results will help to inform design and aid in the establishment of robust, long-term performance measures.