Kinematics of Meshing Surfaces Using Geometric Algebra

2003 ◽  
Author(s):  
Scott M. Miller
Keyword(s):  
Geometric Algebra ◽  
Screw Theory ◽  
Three Dimensional ◽  
Normal Vector ◽  
The Past ◽  
Geometric Concepts ◽  
Vector Algebra ◽  
The Common ◽  
Two Bodies ◽  
Theoretical Developments

As is well known, analysis of two surfaces in mesh plays a fundamental role in gear theory. In the past, special coordinate systems, vector algebra, or screw theory was used to analyze the kinematics of meshing. The approach here instead relies on geometric algebra, an extension of conventional vector algebra. The elegance of geometric algebra for theoretical developments is demonstrated by examining the so-called “equation of meshing,” which requires that the relative velocity of two bodies at a point of contact be perpendicular to the common surface normal vector. With surprisingly little effort, several alternative forms of the equation of meshing are generated and, subsequently, interpreted geometrically. Via straightforward algebraic manipulations, the results of screw theory and vector algebra are unified. Due to the simplicity with which complex geometric concepts are expressed and manipulated, the effort required to grasp the general three-dimensional meshing of surfaces is minimized.

Review of Joost Kalker’s Wheel-Rail Contact Theories and Their Implementation in Multibody Codes

2009 ◽  
Author(s):  
Khaled E. Zaazaa ◽  
A. L. Schwab
Keyword(s):  
Three Dimensional ◽  
Rolling Contact ◽  
Contact Theory ◽  
Spin Moment ◽  
Empirical Theory ◽  
The Past ◽  
Strip Theory ◽  
Tangential Forces ◽  
Two Bodies ◽  
Conformal Contact

During the past decades Kalker developed a number of wheel-rail contact theories that can be used to determine the tangential forces and spin moment between the wheel and the rail [Kalker, 1990]. These theories are: Linear Theory, Strip Theory, Empirical Theory, Simplified Theory and Exact Three Dimensional Rolling Contact Theory. These theories assume that the contact between the two bodies is non-conformal. Recently, Li and Kalker [Li and Kalker 1998a, 1998b and Li, 2002] introduced an approach for numerical solution of the conformal contact between the wheel and the rail. In this paper, Kalker’s wheel-rail contact theories are presented. The paper provides an overview for each theory and its restriction or error as was reported by Kalker. In addition, a systematic procedure for implementing Kalkers’s wheel-rail contact theories in multibody codes is briefly presented.

An IBM PC-based system for generating three-dimensional reconstructions from serial electron micrographs

1986 ◽  
Vol 44 ◽  
pp. 876-877
Author(s):  
ohn C. Kinnamon ◽  
Stephen J. Young ◽  
Terri A. Sherman
Keyword(s):  
Electron Micrographs ◽  
Serial Section ◽  
Three Dimensional ◽  
The Past ◽  
Biological Structures ◽  
The Common ◽  
Common Problems ◽  
Section Analysis ◽  
Ibm Pc

ne of the common problems confronting the morphologist is the elucidation f the three-dimensional (3-D) nature of biological structures from twoimensional micrographs. Serial section analysis can alleviate this problem omewhat, but it becomes increasingly difficult to mentally reconstruct tructures encompassing more than a few sections. For the past decade, the se of computers has been applied to the generation of 3-D reconstructions rom serial micrographs. Until recently, however, the costs of both ardware and software for 3-D reconstructions have been prohibitively xpensive for most laboratories.

A Model of Inlet Circumferential Fluctuation in Compressor Cascades

2020 ◽  
Author(s):  
Zixuan Yue ◽  
Zefeng Li ◽  
Donghai Jin ◽  
Xingmin Gui
Keyword(s):  
Three Dimensional ◽  
Governing Equations ◽  
Sweep Angle ◽  
Fast Calculation ◽  
The Past ◽  
Through Flow ◽  
The Common ◽  
And Performance ◽  
Turbomachinery Design ◽  
Inaccurate Result

Abstract Through-flow methods are widely used in turbomachinery design and performance prediction due to its fast calculation. In the past, circumferentially-averaging through-flow methods tended to ignore circumferential fluctuation source term (CFST) in the governing equations, leading to an inaccurate result when blades showed a strong three-dimensional feature. To solve this problem, CFST needs to be properly modeled. In this paper, three-dimensional numerical simulation is conducted to find the area where CFST dominates. The influence of inlet Mach number, incidence, camber angles and sweep angle on the CFST in this area is analyzed. A model for CFST is constructed. Three-dimensional verification of this model suggests that within the common scope of use of aerospace compressor designing, this model shows a good accuracy.

Kaysam. A Casting Process for the Manufacture of Rubber Products from Latex

1937 ◽  
Vol 10 (2) ◽  
pp. 352-355
Author(s):  
David Roy Cutler
Keyword(s):  
Three Dimensional ◽  
Casting Process ◽  
Drying Method ◽  
The Past ◽  
Dimensional Shrinkage ◽  
Volume Production ◽  
The Common ◽  
Latex Compounding ◽  
Limitation Of Size ◽  
Experimental Effort

Abstract Various practicable methods of applying the solids of latex and latex mixtures in the manufacture of various types of products have been employed in this country during the past years. While meritorious within their respective fields, these processes, except that for the production of sponge rubber, all have the common limitation of being applicable only to comparatively thin articles of relatively uniform thickness. The recent introduction into this country of an important English invention, Kaysam, supplies the positive three-dimensional shrinkage control and accelerated drying method, which now opens new fields to all types of products with superior strength, stretch, tear-resistance, aging, and advantages characteristic of articles made directly of latex. The Kaysam Development Confronted with the conflicting problems of distressing competition and the necessarily wasteful and uneconomic methods of producing crepe rubber soles, Walter Kay, of Sam Kay & Co., Bury, England, despaired, of meeting the problem except by some workable substitution of latex for crepe rubber. The result of his experimental effort was a workable process of casting liquid latex into rubber articles without limitation of size or shape. This process became known as “Kaysam,” a contracted inversion of his company's name. This process has been applied in England during the past several years, and in various continental European countries to the volume production of many types of soles, metal-inserted heels, cloth-inserted boots, and various kinds of molded articles, including those of solid and hollow construction. More recently still, Kaysam, supplemented by other important inventions of prominent American technologists relating to the fundamentals of latex compounding and use, has been made available to manufacturers in this country by the Kaysam Corporation of America.

Mitochondrial Reconstructions Based on Serial Thick Sections and HVEM

1975 ◽  
Vol 33 ◽  
pp. 286-287
Author(s):  
Jerome J. Paulin
Keyword(s):  
Imaging Techniques ◽  
Three Dimensional ◽  
Posterior Pole ◽  
Dimensional Structure ◽  
Stereo Imaging ◽  
Thin Sections ◽  
Anatomical Features ◽  
The Past ◽  
Cellular Components ◽  
Mitochondrial Reticulum

Within the past decade it has become apparent that HVEM offers the biologist a means to explore the three-dimensional structure of cells and/or organelles. Stereo-imaging of thick sections (e.g. 0.25-10 μm) not only reveals anatomical features of cellular components, but also reduces errors of interpretation associated with overlap of structures seen in thick sections. Concomitant with stereo-imaging techniques conventional serial Sectioning methods developed with thin sections have been adopted to serial thick sections (≥ 0.25 μm). Three-dimensional reconstructions of the chondriome of several species of trypanosomatid flagellates have been made from tracings of mitochondrial profiles on cellulose acetate sheets. The sheets are flooded with acetone, gluing them together, and the model sawed from the composite and redrawn.The extensive mitochondrial reticulum can be seen in consecutive thick sections of (0.25 μm thick) Crithidia fasciculata (Figs. 1-2). Profiles of the mitochondrion are distinguishable from the anterior apex of the cell (small arrow, Fig. 1) to the posterior pole (small arrow, Fig. 2).

Beyond Promoter: The Role of Macrophage in Invasion and Progression of Renal Cell Carcinoma

2020 ◽  
Vol 15 (7) ◽  
pp. 588-596
Author(s):  
Haibao Zhang ◽  
Guodong Zhu
Keyword(s):  
Renal Cell Carcinoma ◽  
Tumor Microenvironment ◽  
Cell Carcinoma ◽  
Renal Cell ◽  
Cell Formation ◽  
Biological Behavior ◽  
Tumor Stem Cell ◽  
The Past ◽  
The Common

Renal cell carcinoma (RCC) is one of the common urologic neoplasms, and its incidence has been increasing over the past several decades; however, its pathogenesis is still unknown up to now. Recent studies have found that in addition to tumor cells, other cells in the tumor microenvironment also affect the biological behavior of the tumor. Among them, macrophages exist in a large amount in tumor microenvironment, and they are generally considered to play a key role in promoting tumorigenesis. Therefore, we summarized the recent researches on macrophage in the invasiveness and progression of RCC in latest years, and we also introduced and discussed many studies about macrophage in RCC to promote angiogenesis by changing tumor microenvironment and inhibit immune response in order to activate tumor progression. Moreover, macrophage interactes with various cytokines to promote tumor proliferation, invasion and metastasis, and it also promotes tumor stem cell formation and induces drug resistance in the progression of RCC. The highlight of this review is to make a summary of the roles of macrophage in the invasion and progression of RCC; at the same time to raise some potential and possible targets for future RCC therapy.

CALCULATION OF THE DEPENDENCE OF THE DISTANCE TO THE LOCATED OBJECT FROM THE CORNER POSITION OF THE VEHICLE LINE

2018 ◽  
pp. 14-18
Author(s):  
V. V. Artyushenko ◽  
A. V. Nikulin
Keyword(s):  
Real Time ◽  
Statistical Physics ◽  
Angular Position ◽  
Three Dimensional ◽  
Line Of Sight ◽  
Two Dimensional ◽  
Radar Station ◽  
Flight Mode ◽  
Vector Algebra ◽  
Analytical Expressions

To simulate echoes from the earth’s surface in the low flight mode, it is necessary to reproduce reliably the delayed reflected sounding signal of the radar in real time. For this, it is necessary to be able to calculate accurately and quickly the dependence of the distance to the object being measured from the angular position of the line of sight of the radar station. Obviously, the simplest expressions for calculating the range can be obtained for a segment or a plane. In the text of the article, analytical expressions for the calculation of range for two-dimensional and three-dimensional cases are obtained. Methods of statistical physics, vector algebra, and the theory of the radar of extended objects were used. Since the calculation of the dependence of the range of the object to the target from the angular position of the line of sight is carried out on the analytical expressions found in the paper, the result obtained is accurate, and due to the relative simplicity of the expressions obtained, the calculation does not require much time.

Searching for Political Parties in the Past

2017 ◽  
Author(s):  
Piero Ignazi
Keyword(s):  
Eighteenth Century ◽  
Political Parties ◽  
Political Party ◽  
Ancient Greece ◽  
Political Community ◽  
Democratic Politics ◽  
The Political ◽  
The Past ◽  
The Common

Chapter 1 introduces the long and difficult process of the theoretical legitimation of the political party as such. The analysis of the meaning and acceptance of ‘parties’ as tools of expressing contrasting visions moves forward from ancient Greece and Rome where (democratic) politics had first become a matter of speculation and practice, and ends up with the first cautious acceptance of parties by eighteenth-century British thinkers. The chapter explores how parties or factions have been constantly considered tools of division of the ‘common wealth’ and the ‘good society’. The holist and monist vision of a harmonious and compounded society, stigmatized parties and factions as an ultimate danger for the political community. Only when a new way of thinking, that is liberalism, emerged, was room for the acceptance of parties set.

Can Groups Assert That P?

2019 ◽  
pp. 326-344
Author(s):  
Deborah Tollefsen
Keyword(s):  
Common Ground ◽  
Speech Act ◽  
Single Individual ◽  
Constitutive Rule ◽  
The Past ◽  
Group Members ◽  
The Common ◽  
Declarative Statement ◽  
John Macfarlane

When a group or institution issues a declarative statement, what sort of speech act is this? Is it the assertion of a single individual (perhaps the group’s spokesperson or leader) or the assertion of all or most of the group members? Or is there a sense in which the group itself asserts that p? If assertion is a speech act, then who is the actor in the case of group assertion? These are the questions this chapter aims to address. Whether groups themselves can make assertions or whether a group of individuals can jointly assert that p depends, in part, on what sort of speech act assertion is. The literature on assertion has burgeoned over the past few years, and there is a great deal of debate regarding the nature of assertion. John MacFarlane has helpfully identified four theories of assertion. Following Sandy Goldberg, we can call these the attitudinal account, the constitutive rule account, the common-ground account, and the commitment account. I shall consider what group assertion might look like under each of these accounts and doing so will help us to examine some of the accounts of group assertion (often presented as theories of group testimony) on offer. I shall argue that, of the four accounts, the commitment account can best be extended to make sense of group assertion in all its various forms.

scholarly journals A Theoretical Framework on the Determinants of Food Purchasing Behavior of the Elderly: A Bibliometric Review with Scientific Mapping in Web of Science

Foods ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 688
Author(s):  
Khaled Alhammadi ◽  
Luna Santos-Roldán ◽  
Luis Javier Cabeza-Ramírez
Keyword(s):  
Elderly Population ◽  
Web Of Science ◽  
The Elderly ◽  
Purchasing Behavior ◽  
Food Purchasing ◽  
The Past ◽  
Bibliometric Review ◽  
Food Market ◽  
The Common ◽  
Elderly Consumers

The past few years have seen significant demographic changes in most regions, including an increased elderly population. Subsequently, elderly citizens comprise an important market segment of consumers, with the food industry one of the most affected areas in this context. However, food market managers previously believed that elderly consumers’ needs were stereotyped in nature. The lack of focus on this sector, therefore, left elderly consumers as an untapped market, without realizing the financial independence of this segment regarding their nutrition. This research will attempt to provide the key determinant factors on elderly consumers’ behavior related to food. For that purpose, a complete literature review of more than 123 papers regarding these concepts has been carried out. Once analyzed, we highlight the common insights to give clear guidance for supermarket managers and food manufacturers to have a better knowledge of the reasons behind elderly people’s food acquisitions.

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