Design of a Variable-Mobility Linkage Using the Bohemian Dome

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
P. C. López-Custodio ◽  
J. S. Dai
Keyword(s):  
Configuration Space ◽  
New Method ◽  
Kinematic Chains ◽  
Paper Folding ◽  
First Time ◽  
The Relationship ◽  
Special Case

A new method is presented for the design of kinematotropic linkages based on 2-DOF kinematic chains that generate more than one surface. As an example of the proposed method, a kinematotropic linkage is obtained by studying a special case of the Bohemian dome which has two different parametrizations constructed by translation of circles and, therefore, two different hybrid kinematic chains can be designed to generate the same Bohemian dome. Each of these hybrid kinematic chains can generate two different surfaces and, thus, can be used in the proposed method. Parametrizations for the secondary surfaces are then obtained and studied. A total of 27 motion branches are found in the configuration space of this kinematotropic linkage. The singularities in the configuration space are further determined using the properties of the surfaces. The resultant linkage offers an explanation of Wholhart’s queer-square linkage other than its original paper folding. As part of the analysis of this example, the relationship between the properties of self-intersections in generated surfaces and the configuration space of the generator linkage is studied for the first time, leading to a description of motion branches related to self-intersections of generated surfaces.

Design of a Variable-Mobility Linkage Using the Bohemian Dome

2018 ◽  
Author(s):  
P. C. López-Custodio ◽  
J. S. Dai
Keyword(s):  
Configuration Space ◽  
Kinematic Chains ◽  
Paper Folding ◽  
First Time ◽  
The Relationship

The properties of the Bohemian dome are studied and it is found that for a particular type of Bohemian dome two different parameterizations based on the translation of circles can be obtained for the same surface, therefore, two different hybrid kinematic chains can be designed to generate the same Bohemian dome. These surface generators are reconfigurable and can generate two different surfaces each. Parameterizations for the secondary surfaces are obtained and studied. These hybrid kinematic chains are used to design a kinematotropic linkage with a total of 27 motion branches in its configuration space. The singularities in the configuration space are also determined using the properties of the surfaces. The resultant linkage offers an explanation of Wholhart’s queer-square linkage other than paper folding. The relationship between the properties of self-intersections in generated surfaces and the configuration space of the generator linkage is studied for the first time leading to the description of motion branches related to self-intersections of generated surfaces.

scholarly journals On rigid origami I: piecewise-planar paper with straight-line creases

2019 ◽  
Vol 475 (2232) ◽  
pp. 20190215 ◽  
Author(s):  
Zeyuan He ◽  
Simon D. Guest
Keyword(s):  
Configuration Space ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Deployable Structures ◽  
Straight Line ◽  
Paper Folding ◽  
Two Dimensional Materials ◽  
Hinge Model ◽  
Special Case ◽  
Important Branch

Origami (paper folding) is an effective tool for transforming two-dimensional materials into three-dimensional structures, and has been widely applied to robots, deployable structures, metamaterials, etc. Rigid origami is an important branch of origami where the facets are rigid, focusing on the kinematics of a panel-hinge model. Here, we develop a theoretical framework for rigid origami, and show how this framework can be used to connect rigid origami and its cognate areas, such as the rigidity theory, graph theory, linkage folding and computer science. First, we give definitions regarding fundamental aspects of rigid origami, then focus on how to describe the configuration space of a creased paper. The shape and 0-connectedness of the configuration space are analysed using algebraic, geometric and numeric methods. In the algebraic part, we study the tangent space and generic rigid-foldability based on the polynomial nature of constraints for a panel-hinge system. In the geometric part, we analyse corresponding spherical linkage folding and discuss the special case when there is no cycle in the interior of a crease pattern. In the numeric part, we review methods to trace folding motion and avoid self-intersection. Our results will be instructive for the mathematical and engineering design of origami structures.

Geometry and Kinematics of a Plane-Symmetric Spatial Eight-Bar Linkage With Exact Straight-Line Motion

2011 ◽  
Author(s):  
Guowu Wei ◽  
Jian S. Dai
Keyword(s):  
Isosceles Triangle ◽  
Plane Symmetric ◽  
Straight Line ◽  
Translation Motion ◽  
Motion Characteristics ◽  
First Time ◽  
The Relationship ◽  
Special Case ◽  
Kinematic Properties ◽  
Geometry And Kinematics

In this paper, a novel plane-symmetric spatial eight-bar linkage with exact straight-line motion is proposed for the first time. Geometry and kinematics of the eight-bar linkage are studied and closed-form equations are presented revealing the exact straight-line motion characteristics of the linkage. It is found in this paper that, for the plane-symmetric eight-bar linkage, the angle α between the base and the straight-line traced by the trajectory of the end-effector point is only dependent on the angle φ of the isosceles triangle vertexes of the linkage but independent of the length of the links and dimension of the vertexes. The relationship between α and φ is studied and a special case that leads to parallel translation motion is revealed. Numerical example is then given to illustrate the kinematic properties of the eight-bar linkage.

The World at Our Fingertips

2021 ◽  
Keyword(s):  
Evolutionary History ◽  
Peripersonal Space ◽  
The Body ◽  
Self Awareness ◽  
Vast Number ◽  
The World ◽  
First Time ◽  
The Relationship ◽  
Special Case ◽  
Perception Action

Where do you end and the external world begin? This might seem to be a straightforward, binary question: your skin is the boundary, with the self on one side and the rest of the world on the other. Peripersonal space shows that the division is not that simple. The boundary is blurrier than you might have thought. Our ability to monitor the space near the body appears to be deeply ingrained. Our evolutionary history has equipped our brains with a special mechanism to track multisensory stimuli that can potentially interact with our physical body in its immediate surroundings and prime appropriate actions. The processing of the immediate space around one’s body thus displays highly specific multisensory and motor features, distinct from those that characterize the processing of regions of space that are further away. The computational specificities here lead one to wonder whether classic theories of perception apply to the special case of peripersonal space. We think that there is a need to reassess the relationship between perception, action, emotion, and self-awareness in the highly special context of the immediate surroundings of our body. For the first time, leading experts on peripersonal space in cognitive psychology, neuropsychology, neuroscience, and ethology gathered in this volume describe the vast number of fascinating discoveries about this special way of representing space. For the first time too, these empirical results and the questions they open are brought into dialogue with philosophy.

Affirmative Action and Leadership Attitudes in Brazilian Women Managers

2011 ◽  
Vol 10 (3) ◽  
pp. 139-143 ◽  
Author(s):  
Gazi Islam ◽  
Sarah E. S. Zilenovsky
Keyword(s):  
Affirmative Action ◽  
Latin American ◽  
Women Managers ◽  
Psychological Effects ◽  
Preferential Selection ◽  
Justice Perceptions ◽  
First Time ◽  
The Relationship

This note examines the relationship between affirmative action (AA) program perceptions and women’s self-ascribed capacity and desire to become leaders. We propose that women who believe that their organization implements a program of preferential selection toward women will experience negative psychological effects leading to lowered self-expectations for leadership, but that this effect will be moderated by their justice perceptions of AA programs. We test this proposition empirically for the first time with a Latin American female sample. Among Brazilian women managers, desire but not self-ascribed capacity to lead was reduced when they believed an AA policy was in place. Both desire’s and capacity’s relationships with belief in an AA policy were moderated by justice perceptions.

SOME OBSERVATIONS ON PREGNANEDIOL EXCRETION DURING THE NORMAL MENSTRUAL CYCLE

1957 ◽  
Vol 24 (3_Suppl) ◽  
pp. S207
Author(s):  
A. Klopper
Keyword(s):  
Menstrual Cycle ◽  
Corpus Luteum ◽  
New Method ◽  
Menstrual Bleeding ◽  
Normal Menstrual Cycle ◽  
The Relationship ◽  
New View

Abstract The changes in view on the significance and amount of urinary pregnanediol in the menstrual cycle are reviewed; in particular the effects of the discovery that the adrenals in both sexes normally contribute to the urinary pregnanediol. Pregnanediol excretion during the menstrual cycle was studied by means of a new method of assay (Klopper et al., 1955) and the results applied to present day concepts of the growth and duration of the corpus luteum. The relationship between pregnanediol excretion and ovulation or the onset of menstrual bleeding was studied. A new view is put forward on the influence of age and parity on the production of progesterone by the corpus luteum.

Document- and Keyword-based Author Co-citation Analysis

2018 ◽  
Vol 2 (2) ◽  
pp. 70-82 ◽  
Author(s):  
Binglu Wang ◽  
Yi Bu ◽  
Win-bin Huang
Keyword(s):  
Citation Analysis ◽  
Semantic Similarity ◽  
Method Validation ◽  
New Method ◽  
Global Network ◽  
Network Visualization ◽  
Knowledge Domain ◽  
Knowledge Domains ◽  
Domain Mapping ◽  
The Relationship

AbstractIn the field of scientometrics, the principal purpose for author co-citation analysis (ACA) is to map knowledge domains by quantifying the relationship between co-cited author pairs. However, traditional ACA has been criticized since its input is insufficiently informative by simply counting authors’ co-citation frequencies. To address this issue, this paper introduces a new method that reconstructs the raw co-citation matrices by regarding document unit counts and keywords of references, named as Document- and Keyword-Based Author Co-Citation Analysis (DKACA). Based on the traditional ACA, DKACA counted co-citation pairs by document units instead of authors from the global network perspective. Moreover, by incorporating the information of keywords from cited papers, DKACA captured their semantic similarity between co-cited papers. In the method validation part, we implemented network visualization and MDS measurement to evaluate the effectiveness of DKACA. Results suggest that the proposed DKACA method not only reveals more insights that are previously unknown but also improves the performance and accuracy of knowledge domain mapping, representing a new basis for further studies.

ЗУБРЫ НА СЕВЕРЕ РОССИИ — НАСТОЯЩЕЕ И БУДУЩЕЕ

2019 ◽  
pp. 42-44
Author(s):  
I.V. GUSAROV ◽  
V.A. OSTAPENKO ◽  
T.V. NOVIKOVА
Keyword(s):  
Biological Diversity ◽  
Climatic Conditions ◽  
Economic Consequences ◽  
European Bison ◽  
Rare And Endangered Species ◽  
The North ◽  
Rare And Endangered ◽  
Relationship Of ◽  
First Time ◽  
The Relationship

Впервые в мире создана популяция зубров на территории 60 градусов северной широты. В новых климатических условиях разведения и сохранения зубров определены и проанализированы факторы существования вида на севере Европейской части РФ. Выявлены признаки, динамика численности, которые являются составной частью системы, предназначенной для управления биоразнообразием. Интродукция, являясь процессом введения в экосистему нехарактерных для нее видов, может усиливать изменения биоценозов как положительно, так и отрицательно. Насколько быстро и успешно проходит процесс адаптации заселенного вида, и усматривается его влияние на окружающую среду зависит дальнейшее существование зубров и в целом биоразнообразия. В статье обсуждаются вопросы взаимоотношения зубров с другими видами копытных и хозяйственной деятельностью человека, а также дальнейшим использованием зубров в сельскохозяйственном производстве. Пластичность зубров, выявление изменений и их анализ при вселении видов в новые условия обитания необходимы не только для определения развития или деградации биоценозов и в целом экосистемы, но и прогноза социально-экономических последствий интродукции как одного из методов сохранения редких и исчезающих видов фауны.For the first time in the world, a bison population has been created in an area of 60 degrees north latitude. In the new climatic conditions of breeding and preservation of bison, the factors of the species existence in the north of the European part of the Russian Federation are identified and analyzed. The signs, dynamics of abundance, which are an integral part of the system designed to manage biodiversity are identified, since the preservation of biological diversity on the planet is one of the main problems of our time. Introduction, being the process of introducing non-typical species into an ecosystem, can enhance changes in biocenoses, both positively and negatively. The question posing sounds especially when it comes to such a large hoofed animal as the European bison. How quickly and successfully the process of adaptation of the universe takes place and its environmental impact is seen depends on the continued existence of bison and biodiversity in general. The article discusses the relationship of bison with other types of ungulates and human activities, as well as the further use of bison in agricultural production. How these issues will be resolved positively depends on the future of these animals. Thus, the plasticity of bison, the identification of changes and their analysis, with the introduction of species into new habitat conditions is necessary not only to determine the development or degradation of biocenoses and the ecosystem as a whole, but also to predict the socio-economic consequences due to the introduction as one of the methods of preserving rare and endangered species of fauna.

A University Education

2017 ◽  
Author(s):  
David Willetts
Keyword(s):  
Higher Education ◽  
Modern Society ◽  
University Education ◽  
Modern World ◽  
Controversial Issues ◽  
The Us ◽  
The Individual ◽  
The University ◽  
First Time ◽  
The Relationship

Universities have a crucial role in the modern world. In England, entrance to universities is by nation-wide competition which means English universities have an exceptional influence on schools--a striking theme of the book. This important book first investigates the university as an institution and then tracks the individual on their journey to and through university. In A University Education, David Willetts presents a compelling case for the ongoing importance of the university, both as one of the great institutions of modern society and as a transformational experience for the individual. The book also makes illuminating comparisons with higher education in other countries, especially the US and Germany. Drawing on his experience as UK Minister for Universities and Science from 2010 to 2014, the author offers a powerful account of the value of higher education and the case for more expansion. He covers controversial issues in which he was involved from access for disadvantaged students to the introduction of L9,000 fees. The final section addresses some of the big questions for the future, such as the the relationship between universities and business, especially in promoting innovation.. He argues that the two great contemporary trends of globalisation and technological innovation will both change the university significantly. This is an authoritative account of English universities setting them for the first time in their new legal and regulatory framework.

scholarly journals Variation in VKORC1 Is Associated with Vascular Dementia

2021 ◽  
Vol 80 (3) ◽  
pp. 1329-1337
Author(s):  
Jure Mur ◽  
Daniel L. McCartney ◽  
Daniel I. Chasman ◽  
Peter M. Visscher ◽  
Graciela Muniz-Terrera ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Vascular Dementia ◽  
Genetic Variant ◽  
Warfarin Dose ◽  
Uk Biobank ◽  
Parental History ◽  
Genome Wide ◽  
History Of ◽  
First Time ◽  
The Relationship

Background: The genetic variant rs9923231 (VKORC1) is associated with differences in the coagulation of blood and consequentially with sensitivity to the drug warfarin. Variation in VKORC1 has been linked in a gene-based test to dementia/Alzheimer’s disease in the parents of participants, with suggestive evidence for an association for rs9923231 (p = 1.8×10–7), which was included in the genome-wide significant KAT8 locus. Objective: Our study aimed to investigate whether the relationship between rs9923231 and dementia persists only for certain dementia sub-types, and if those taking warfarin are at greater risk. Methods: We used logistic regression and data from 238,195 participants from UK Biobank to examine the relationship between VKORC1, risk of dementia, and the interplay with warfarin use. Results: Parental history of dementia, APOE variant, atrial fibrillation, diabetes, hypertension, and hypercholesterolemia all had strong associations with vascular dementia (p < 4.6×10–6). The T-allele in rs9923231 was linked to a lower warfarin dose (βperT - allele = –0.29, p < 2×10–16) and risk of vascular dementia (OR = 1.17, p = 0.010), but not other dementia sub-types. However, the risk of vascular dementia was not affected by warfarin use in carriers of the T-allele. Conclusion: Our study reports for the first time an association between rs9923231 and vascular dementia, but further research is warranted to explore potential mechanisms and specify the relationship between rs9923231 and features of vascular dementia.

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