An accidental visualization of the Brillouin zone in an Ni–W alloyviadiffuse scattering

2013 ◽  
Vol 46 (4) ◽  
pp. 1211-1215 ◽  
Author(s):  
Sascha B. Maisel ◽  
Nils Schindzielorz ◽  
Stefan Müller ◽  
Harald Reichert ◽  
Alexei Bosak
Keyword(s):  
Fermi Surface ◽  
Brillouin Zone ◽  
Expansion Method ◽  
Reciprocal Space ◽  
Three Dimensions ◽  
X Rays ◽  
Solid State Physics ◽  
Seitz Cell ◽  
The Face ◽  
The Given

Solid state physics is built on the concept of reciprocal space. The physics of any given periodic crystal is fully defined within the Wigner–Seitz cell in reciprocal space, also known as the first Brillouin zone. It is a purely symmetry-based concept and usually does not have any eye-catching signature in the experimental data, in contrast with some other geometrical constructions like the Fermi surface. However, the particular shape of the Fermi surface of nickel allowed the visualization of the system of edges (skeleton) of the Wigner–Seitz cell of the face-centred cubic lattice in reciprocal space in three dimensions by the diffuse scattering of X-rays from Ni1−xWx(x= 0.03, 0.05, 0.08) single crystals. Employing a cluster-expansion method with first-principles input, it is possible to show that the observed scattering is inherent to the given nickel alloys and the crystal structures they form. This peculiar feature can be understood by considering the shape of the Fermi surface of pure nickel.

scholarly journals Determination of the Vertical Dimension and the Position of the Occlusal Plane in a Removable Prosthesis Using Cephalometric Analysis and Golden Proportion

2021 ◽  
Vol 11 (15) ◽  
pp. 6948
Author(s):  
Gabriele Cervino ◽  
Sergio Sambataro ◽  
Chiara Stumpo ◽  
Salvatore Bocchieri ◽  
Fausto Murabito ◽  
...  
Keyword(s):  
Vertical Dimension ◽  
Occlusal Plane ◽  
X Rays ◽  
Common Procedure ◽  
Lower Incisor ◽  
Golden Proportion ◽  
The Face ◽  
Removable Prosthesis ◽  
Edentulous Patients

The aim of this study is to demonstrate the use and the effectiveness of cephalometry and golden proportions analysis of the face in planning prosthetic treatments in totally edentulous patients. In order to apply this method, latero-lateral and posterior-anterior X-rays must be performed in addition to the common procedure. Two main concerns for totally edentulous patients are the establishment of the vertical dimension and the new position of the occlusal plane. The divine proportion analysis was carried out by the use of a golden divider. The prosthetic protocol was divided into three steps and a case was selected for better understanding. Referring to the golden relations, if the distance from the chin to the wing of the nose is 1.0, the distance from the nose to eye is 0.618. This proportion is useful and effective in determining the correct prosthetic vertical dimension. The incisal margin of the lower incisor must be positioned between Point A (A) and protuberance menti (Pm) according to the gold ratio 0.618 of the total height A-Pm. Posteriorly the occlusal plane must be placed 2 mm below the divine occlusal plane (traced from the incisal margin of lower incisors to Xi point). A prosthesis made in accordance with cephalometric parameters and divine proportions of the face helps to improve the patient’s aesthetics, function and social personality.

“Cartography” in 7-Dimensions at CHESS: Mapping of Structure in Real Space, Reciprocal Space, and Time Using High-Energy X-rays

2020 ◽  
Vol 33 (6) ◽  
pp. 11-16
Author(s):  
K. E. Nygren, ◽  
D. C. Pagan, ◽  
J. P. C. Ruff ◽  
E. Arenholz ◽  
J. D. Brock
Keyword(s):  
High Energy ◽  
Real Space ◽  
Reciprocal Space ◽  
X Rays ◽  
Space And Time

scholarly journals An Assessment of Skeletal Craniofacial Asymmetry in South Indian Population

2012 ◽  
Vol 13 (1) ◽  
pp. 80-84 ◽  
Author(s):  
G Anil Kumar ◽  
Saibel Farishta ◽  
G Baiju ◽  
VK Taneja ◽  
RC Minocha ◽  
...  
Keyword(s):  
College Students ◽  
South India ◽  
Indian Population ◽  
Cranial Base ◽  
The Other ◽  
South Indian Population ◽  
X Rays ◽  
Base Area ◽  
South Indian ◽  
The Face

ABSTRACT The present study was undertaken to assess the skeletal craniofacial asymmetry in South Indian population by a posteroanterior cephalometric radiographic method. The skeletal craniofacial structures on one side of the face were compared with that of the other, by drawing various triangles representing different craniofacial regions. The sample consisted of 60 subjects (30 males and 30 females) aged between 18 to 25 years, who were mainly dental college students from South India. Overall 52 X-rays were obtained, with four errors each in the male and the female groups. The results revealed that the total facial structures in the South Indian population were larger on the left side (statistically insignificant). The cranial base area exhibited a greater degree of asymmetry than any other component area of the face, which might be due to the inaccuracy at the condylar point. How to cite this article Taneja VK, Kumar GA, Farishta S, Minocha RC, Baiju G, Gopal D. An Assessment of Skeletal Craniofacial Asymmetry in South Indian Population. J Contemp Dent Pract 2012;13(1):80-84.

Manufacturability Analysis for Solid Freeform Fabrication

1999 ◽  
Author(s):  
R. K. Arni ◽  
S. K. Gupta
Keyword(s):  
Systematic Approach ◽  
Solid Freeform Fabrication ◽  
Second Step ◽  
Freeform Fabrication ◽  
Design Tolerance ◽  
The Face ◽  
The Right ◽  
The Given ◽  
Manufacturing Problems ◽  
Case Effect

Abstract This paper describes a systematic approach to analyzing manufacturability of parts produced using Solid Freeform Fabrication (SFF) processes with flatness, parallelism and perpendicularity tolerance requirements on the planar faces of the part. SFF processes approximate objects using layers, therefore the part being produced exhibits stair-case effect. The extent of this stair-case effect depends on the angle between the build orientation and the face normal. Therefore, different faces whose direction normal is oriented differently with respect to the build direction may exhibit different values of inaccuracies. We use a two step approach to perform the manufacturability analysis. We first analyze each specified tolerance on the part and identify the set of feasible build directions that can be used to satisfy that tolerance. As a second step, we take the intersection of all sets of feasible build directions to identify the set of build directions that can simultaneously satisfy all specified tolerance requirements. If there is at least one build direction that can satisfy all tolerance requirements, then the part is considered manufacturable. Otherwise, the part is considered non-manufacturable. Our research will help SFF designers and process providers in the following ways. By evaluating design tolerances against a given process capability, it will help designers in eliminating manufacturing problems and selecting the right SFF process for the given design. It will help process providers in selecting a build direction that can meet all design tolerance requirements.

scholarly journals Adherence to best care practices in normal birth: construction and validation of an instrument

2015 ◽  
Vol 49 (6) ◽  
pp. 889-897 ◽  
Author(s):  
Elisabete Mesquita Peres de Carvalho ◽  
Leila Bernarda Donato Göttems ◽  
Maria Raquel Gomes Maia Pires
Keyword(s):  
Content Validity ◽  
Semantic Analysis ◽  
Three Dimensions ◽  
Work Processes ◽  
Evidence Based Practices ◽  
Normal Birth ◽  
Pregnancy And Childbirth ◽  
Healthcare Network ◽  
The Face ◽  
Care Practices

Abstract OBJECTIVE To describe the stages of construction and validation of an instrument in order to analyze the adherence to best care practices during labour and birth. METHOD Methodological research, carried out in three steps: construction of dimensions and items, face and content validity and semantic analysis of the items. RESULTS The face and content validity was carried out by 10 judges working in healthcare, teaching and research. Items with Content Validity Index (CVI) ≥ 0.9 were kept in full or undergone revisions as suggested by the judges. Semantic analysis, performed twice, indicated that there was no difficulty in understanding the items. CONCLUSION The instrument with three dimensions (organization of healthcare network to pregnancy and childbirth, evidence-based practices and work processes) followed the steps recommended in the literature, concluded with 50 items and total CVI of 0.98.

A two-stage approximation strategy for piecewise smooth functions in two and three dimensions

2021 ◽  
Author(s):  
Sergio Amat ◽  
David Levin ◽  
Juan Ruiz-Álvarez
Keyword(s):  
Piecewise Smooth ◽  
Three Dimensions ◽  
System Of Equations ◽  
Global Approximation ◽  
Smooth Functions ◽  
Approximation Techniques ◽  
Second Stage ◽  
Principle Of Matching ◽  
The Given ◽  
Standard Approximation

Abstract Given values of a piecewise smooth function $f$ on a square grid within a domain $[0,1]^d$, $d=2,3$, we look for a piecewise adaptive approximation to $f$. Standard approximation techniques achieve reduced approximation orders near the boundary of the domain and near curves of jump singularities of the function or its derivatives. The insight used here is that the behavior near the boundaries, or near a singularity curve, is fully characterized and identified by the values of certain differences of the data across the boundary and across the singularity curve. We refer to these values as the signature of $f$. In this paper, we aim at using these values in order to define the approximation. That is, we look for an approximation whose signature is matched to the signature of $f$. Given function data on a grid, assuming the function is piecewise smooth, first, the singularity structure of the function is identified. For example, in the two-dimensional case, we find an approximation to the curves separating between smooth segments of $f$. Secondly, simultaneously, we find the approximations to the different segments of $f$. A system of equations derived from the principle of matching the signature of the approximation and the function with respect to the given grid defines a first stage approximation. A second stage improved approximation is constructed using a global approximation to the error obtained in the first stage approximation.

Critical analysis of laws and policies for the prevention of petroleum pipeline vandalization in Nigeria

2021 ◽  
Vol 23 (4) ◽  
pp. 305-320
Author(s):  
Edward O. Okumagba
Keyword(s):  
Critical Analysis ◽  
Justice System ◽  
Critical Assessment ◽  
X Rays ◽  
Life Imprisonment ◽  
Production And Distribution ◽  
The Face ◽  
Laws And Policies ◽  
Legal Frameworks ◽  
Source Materials

The loss of an estimated $4.5 billion in 2020 by Nigeria to petroleum pipeline vandalism and crude oil theft has necessitated a critical assessment of the legal frameworks for the prevention of petroleum pipeline vandalism in Nigeria. This paper utilizes source materials relating to the title by examining the impacts of existing legal frameworks for the prevention of petroleum pipeline vandalization in Nigeria. It x-rays amongst others the provisions of sections 2 and 7 of the Petroleum Production and Distribution (Anti-Sabotage) Act and Miscellaneous Offences Act which imposes the death penalty and life imprisonment with the aim of deterring offenders without creating a court to try offenders. It reveals that in the face of such stringent sanctions, the activities of petroleum pipeline vandalism have continued unabated albeit a thriving business that is likely to arm the Nigerian economy in COVID-19 pandemic era. In addition, with an already perceived “compromised” criminal justice system, the paper concludes by advocating for change in policy strategy that will include the creation of a special court by amending existing legal frameworks to try offenders of the activities of petroleum pipeline vandalization.

A Context-Aware Model of Trust for Facilitating Secure Ad Hoc Collaborations

2010 ◽  
pp. 250-281 ◽  
Author(s):  
Indrajit Ray ◽  
Indrakshi Ray ◽  
Sudip Chakraborty
Keyword(s):  
Incomplete Information ◽  
Ad Hoc ◽  
Sensitive Information ◽  
Trust Value ◽  
Trust Relationships ◽  
The Face ◽  
Trust Models ◽  
Almost All ◽  
Ad Hoc Collaborations ◽  
The Given

Ad hoc collaborations often necessitate impromptu sharing of sensitive information or resources between member organizations. Each member of resulting collaboration needs to carefully assess and tradeoff the requirements of protecting its own sensitive information against the requirements of sharing some or all of them. The challenge is that no policies have been previously arrived at for such secure sharing (since the collaboration has been formed in an ad hoc manner). Thus, it needs to be done based on an evaluation of the trustworthiness of the recipient of the information or resources. In this chapter, the authors discuss some previously proposed trust models to determine if they can be effectively used to compute trustworthiness for such sharing purposes in ad hoc collaborations. Unfortunately, none of these models appear to be completely satisfactory. Almost all of them fail to satisfy one or more of the following requirements: (i) well defined techniques and procedures to evaluate and/or measure trust relationships, (ii) techniques to compare and compose trust values which are needed in the formation of collaborations, and (iii) techniques to evaluate trust in the face of incomplete information. This prompts the authors to propose a new vector (we use the term “vector” loosely; vector in this work means a tuple) model of trust that is suitable for reasoning about the trustworthiness of systems built from the integration of multiple subsystems, such as ad hoc collaborations. They identify three parameters on which trust depends and formulate how to evaluate trust relationships. The trust relationship between a truster and a trustee is associated with a context and depends on the experience, knowledge, and recommendation that the truster has with respect to the trustee in the given context. The authors show how their model can measure trust in a given context. Sometimes enough information is not available about a given context to calculate the trust value. Towards this end the authors show how the relationships between different contexts can be captured using a context graph. Formalizing the relationships between contexts allows us to extrapolate values from related contexts to approximate a trust value of an entity even when all the information needed to calculate the trust value is not available. Finally, the authors develop formalisms to compare two trust relationships and to compose two or more of the same – features that are invaluable in ad hoc collaborations.

Diffraction

2002 ◽  
Author(s):  
David Blow
Keyword(s):  
Red Light ◽  
Three Dimensional ◽  
Three Dimensions ◽  
X Rays ◽  
X Ray ◽  
Original Direction ◽  
Computational Procedures ◽  
Scattering Material ◽  
Opaque Object ◽  
Diffraction Effects

Diffraction refers to the effects observed when light is scattered into directions other than the original direction of the light, without change of wavelength. An X-ray photon may interact with an electron and set the electron oscillating with the X-ray frequency. The oscillating electron may radiate an X-ray photon of the same wavelength, in a random direction, when it returns to its unexcited state. Other processes may also occur, akin to fluorescence, which emit X-rays of longer wavelengths, but these processes do not give diffraction effects. Just as we see a red card because red light is scattered off the card into our eyes, objects are observed with X-rays because an illuminating X-ray beam is scattered into the X-ray detector. Our eye can analyse details of the card because its lens forms an image on the retina. Since no X-ray lens is available, the scattered X-ray beam cannot be converted directly into an image. Indirect computational procedures have to be used instead. X-rays are penetrating radiation, and can be scattered from electrons throughout the whole scattering object, while light only shows the external shape of an opaque object like a red card. This allows X-rays to provide a truly three-dimensional image. When X-rays pass near an atom, only a tiny fraction of them is scattered: most of the X-rays pass further into the object, and usually most of them come straight out the other side of the whole object. In forming an image, these ‘straight through’ X-rays tell us nothing about the structure, and they are usually captured by a beam stop and ignored. This chapter begins by explaining that the diffraction of light or X-rays can provide a precise physical realization of Fourier’s method of analysing a regularly repeating function. This method may be used to study regularly repeating distributions of scattering material. Beginning in one dimension, examples will be used to bring out some fundamental features of diffraction analysis. Graphic examples of two-dimensional diffraction provide further demonstrations. Although the analysis in three dimensions depends on exactly the same principles, diffraction by a three-dimensional crystal raises additional complications.

Introduction

1990 ◽  
Author(s):  
Steven Kim
Keyword(s):  
New York ◽  
Difficult Problem ◽  
Two Dimensions ◽  
Three Dimensions ◽  
High Yield ◽  
Acceptable Solution ◽  
Theory Of Intelligence ◽  
Creative Solutions ◽  
The World ◽  
The Face

The world around us abounds with problems requiring creative solutions. Some of these are naturally induced, as when an earthquake levels a city or an epidemic decimates a population. Others are products of our own creation, as in the “need” to curb pollution, to develop a theory of intelligence, or to compose works of art. Still others are a combination of both, as in the development of high-yield grains to feed an overpopulated planet, or the maintenance of health in the face of ravaging diseases. The word problem is used in a general sense to refer to any mental activity having some recognizable goal. The goal itself may not be apparent beforehand. Problems may be characterized by three dimensions relating to domain, difficulty, and size. These attributes are depicted in Figure 1.1. The domain refers to the realm of application. These realms may relate to the sciences, technology, arts, or social crafts. The dimension of difficulty pertains to the conceptual challenge involved in identifying an acceptable solution to the problem. A difficult problem, then, is one that admits no obvious solution, nor even a well-defined approach to seeking it. The size denotes the magnitude of work or resources required to develop a solution and implement it. This attribute differs from the notion of difficulty in that it applies to the stage that comes after a solution has been identified. In other words, difficulty refers to the prior burden in defining a problem or identifying a solution, while size describes the amount of work required to implement or realize the solution once it has jelled conceptually. For convenience in representation on a 2-dimensional page, the domain axis may be compressed into the plane of other attributes. The result is Figure 1.2, which presents sample problems to illustrate the two dimensions of difficulty and size. Cleaning up spilled milk is a trivial problem having numerous simple solutions. In contrast, refacing the subway trains in New York City with a fresh coat of paint is a formidable task that could require hundreds of workyears of effort.

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