Review and Assessment of Ratcheting Considerations for Design and Analysis

2010 ◽  
Author(s):  
Yogendra S. Garud
Keyword(s):  
Kinematic Hardening ◽  
Structural Response ◽  
Material Point ◽  
Multiaxial Loading ◽  
Key Characteristics ◽  
Response Versus ◽  
Material Creep ◽  
Plastic Shakedown ◽  
The Impact

This paper presents theoretical, practical, and computational considerations of significance in assessing the strain ratcheting under combined cyclic loads. Different aspects of ratcheting are covered comparing uniaxial versus multiaxial loading. Since ratcheting and (elastic or plastic) shakedown are generally influenced by the same underlying factors, the conditions under which shakedown is more likely to be the end result are reviewed with reference to the material response versus the structural response. A simple two-bar model is used to illustrate the key characteristics of ratcheting and the essential factors or conditions responsible for the ratcheting. For example, the role of material strain hardening vs. kinematic hardening, and the effects of non-symmetry in loading or material yielding are examined. The role of structural constraint in determining the actual ratcheting response of components as compared to the material (point) response is discussed. Based on the review and assessment of these observations the resulting practical considerations in limiting the impact of ratcheting are discussed. The ratcheting considerations in this paper are limited to the time independent deformation or plasticity, excluding the additional effect of time-dependent phenomena such as the material creep or stress relaxation.

The academic profession in Russia’s two capitals: The impact of 20 years of transition

2017 ◽  
Vol 16 (5) ◽  
pp. 626-644 ◽  
Author(s):  
Elizaveta Sivak ◽  
Maria Yudkevich
Keyword(s):  
Large Scale ◽  
Academic Career ◽  
Academic Profession ◽  
University Faculty ◽  
Key Characteristics ◽  
Personal Strain ◽  
High Degree ◽  
The Impact ◽  
Russian Universities

This paper studies the dynamics of key characteristics of the academic profession in Russia based on the analysis of university faculty in the two largest cities in Russia – Moscow and St Petersburg. We use data on Russian university faculty from two large-scale comparative studies of the academic profession (‘The Carnegie Study’ carried out in 1992 in 14 countries, including Russia, and ‘The Changing Academic Profession Study’, 2007–2012, with 19 participating countries and which Russia joined in 2012) to look at how faculty’s characteristics and attitudes toward different aspects of their academic life changed over 20 years (1992–2011) such as faculty’s views on reasons to leave or to stay at a university, on university’s management and the role of faculty in decision making. Using the example of universities in the two largest Russian cities, we demonstrate that the high degree of overall centralization of governance in Russian universities barely changed in 20 years. Our paper provides comparisons of teaching/research preferences and views on statements concerning personal strain associated with work, academic career perspectives, etc., not only in Russian universities between the years 1992 and 2012, but also in Russia and other ‘Changing Academic Profession’ countries.

scholarly journals Foreign Investors vs. National Tax Measures: Assessing the Role of International Investment Agreements

2021 ◽  
pp. 149-169
Author(s):  
Julien Chaisse ◽  
Jamieson Kirkwood
Keyword(s):  
International Investment ◽  
Foreign Investors ◽  
International Investment Agreements ◽  
Key Characteristics ◽  
Recent Trends ◽  
National Tax ◽  
Definition Of ◽  
The Impact ◽  
Investment Agreements

AbstractThis chapter focuses on the impact of the international law of foreign investment on tax issues with a view to assessing the interactions between the two regimes and identifying potential signs of convergence. In particular, this chapter focuses on the operation of International Investment Agreements (IIAs) and assesses the role of IIAs from the perspective of foreign investors vis-à-vis National Tax Measures (NTMs). Part I of this chapter provides an understanding of the convergence between investment law and tax issues. This aids in an understanding of the key characteristics of IIAs (such as the definition of investment and the use of specific tax exceptions) and the relationship between currently existing IIAs and tax disputes. Part II analyzes, both quantitatively and qualitatively, the recent trends of tax disputes in investment arbitration. Part III assesses how tax can be seen as the last barrier to cross border investment. Part IV concludes.

Gimme shelter or fade away: the impact of regional entrepreneurial ecosystem quality on venture survival

2019 ◽  
Vol 28 (4) ◽  
pp. 827-854 ◽  
Author(s):  
Siddharth Vedula ◽  
Phillip H Kim
Keyword(s):  
Entrepreneurial Ecosystem ◽  
Ecosystem Quality ◽  
Support Organizations ◽  
Key Characteristics ◽  
Serial Entrepreneurs ◽  
Innovation Capacity ◽  
The Impact ◽  
The Relationship

Abstract Our study addresses a popular question in entrepreneurship research—to what extent does the quality of a region’s entrepreneurial ecosystem matter for venture survival? To tackle this question, we created a regional entrepreneurial ecosystem quality index based on five key characteristics: supportive entrepreneurial culture, access to finance, availability of human capital, innovation capacity, and formal support organizations. We analyze 301 United States Metropolitan Statistical Areas for these characteristics and measure the aggregated contextual influence on venture survival within these regions over time. In addition to analyzing the relationship between this index and venture survival, we also consider the moderating role of founders’ experience on survival outcomes. Our findings confirm that, in general, higher quality ecosystems shelter ventures, while ventures in weaker ecosystems are more likely to fade away and fail. However, for serial entrepreneurs, we find that ecosystem quality has a much smaller impact on venture survival.

Modeling of the impact of rigid ellipsoidal blocks by means of an elastic-visco-plastic constitutive model 

2021 ◽  
Author(s):  
Giuseppe Dattola ◽  
Giovanni Battista Crosta ◽  
Claudio Giulio di Prisco
Keyword(s):  
Constitutive Model ◽  
Three Dimensional ◽  
Impact Angle ◽  
Material Point ◽  
Lumped Mass ◽  
Mountain Areas ◽  
Block Motion ◽  
The Impact ◽  
Constitutive Parameters

<p>Rockfall is one of the most common hazards in mountain areas causing severe damages to structures/infrastructures and, human lives. For this reason, numerous are the papers published in the last decades on this subject, both introducing reliable approaches to simulate the boulder trajectory and defining design methods for sheltering structures. As is well known, the most popular strategy to simulate the block trajectory and velocity is based on the lumped mass material point approach. This is capable of describing the block trajectory, before either its natural arrest or impact against an artificial/natural obstacle, by suitably considering its interaction with soil/rock materials, interaction always dynamic, very often highly dissipative and defined, according to its nature, as sliding, rolling or impact.</p><p>In this framework, this study focusses on impacts and, in particular, on the role of block geometry in affecting the block kinematic response. The problem is approached numerically; by modifying a previously conceived elastic-viscoplastic constitutive model, based on the macro-element concept. and capable of satisfactorily simulating impacts of spherical blocks.</p><p>The modified constitutive model relaxes the assumption of spherical block by assuming an ellipsoidal shape and by allowing for the boulder rotation. These two changes make the problem more complex but allow to model more realistically the impact. For the sake of simplicity, the results shown in this work consider the block motion to be planar, but the model already allows to include general three dimensional conditions.</p><p>In this work, the model is briefly outlined and the procedure for calibrating the model constitutive parameters described. Then, the results of an extensive parametric analysis, employing constitutive parameters calibrated on experimental data taken from the literature, are discussed. In particular, the role of (i) the inner block orientation, and (ii) the inner impact angle is considered in terms of both kinematic variables and restitution coefficients. Finally, interpolation functions to compute restitution coefficients, once both block shape and inner impact block orientation are known, are provided.</p>

scholarly journals Does ‘clicking’ matter? The role of online participation in adolescents’ civic development

2017 ◽  
Vol 11 (4) ◽  
Author(s):  
Hana Machackova ◽  
Jan Šerek
Keyword(s):  
Self Efficacy ◽  
Civic Participation ◽  
Panel Study ◽  
Civic Identity ◽  
Civic Development ◽  
Online Participation ◽  
The Czech Republic ◽  
Key Characteristics ◽  
The Impact

This study focuses on the role of online civic participation in the civic development of adolescents. We build on the assumption that online civic participation differs from more traditional offline civic participation in several key characteristics, namely lacking proximity to other actors, possible disconnection between civic actions and their outcomes, and a reduced hierarchy within the online environment. Considering these specifics, the study examined the longitudinal effect of online participation on the development of civic identity, political self-efficacy, and attitudes toward social authorities. Concurrently, we contrasted the impact of online participation with the impact of offline civic participation. Data from a survey-based two-wave panel study conducted in Spring 2014 and Autumn 2015 in the Czech Republic were utilized. The sample comprised 768 adolescents (aged 14-17 in T1; 54% females). The results showed that online participation predicted increased challenging attitudes towards social authorities, while offline participation had the opposite effect. Furthermore, online participation had no effect on political self-efficacy or civic development, but offline participation positively predicted civic identity. The findings are discussed with regard to the specific benefits and limits of online civic participation.

scholarly journals Human rights litigation and the ‘war on terror’

2008 ◽  
Vol 90 (871) ◽  
pp. 573-597 ◽  
Author(s):  
Helen Duffy
Keyword(s):  
Human Rights ◽  
War On Terror ◽  
Human Rights Violations ◽  
Key Characteristics ◽  
Human Rights Norms ◽  
The Impact

AbstractThe ‘war on terror’ has led to grave human rights violations and, in response, to a growing volume of human rights litigation. This article provides an overview of litigation that has unfolded in recent years in relation to issues such as arbitrary detention, torture and ill-treatment, extraordinary rendition, extraterritorial application of human rights norms and the creeping reach of the ‘terrorism’ label. These cases provide a prism through which are displayed key characteristics of the war on terror as it affects human rights, and enables us to begin to ask questions regarding the role of the courts and the impact of human rights litigation in this area.

scholarly journals Myeloid cells as therapeutic targets in neuroinflammation after stroke: Specific roles of neutrophils and neutrophil–platelet interactions

2018 ◽  
Vol 38 (12) ◽  
pp. 2150-2164 ◽  
Author(s):  
Alicia García-Culebras ◽  
Violeta Durán-Laforet ◽  
Carolina Peña-Martínez ◽  
Iván Ballesteros ◽  
Jesús M Pradillo ◽  
...  
Keyword(s):  
Cell Lineage ◽  
Myeloid Cell ◽  
Stroke Outcome ◽  
Local Inflammatory Response ◽  
Injured Brain ◽  
Ischemic Tissue ◽  
Key Characteristics ◽  
Cellular Phenotypes ◽  
The Impact

Ischemic brain injury causes a local inflammatory response, involving the activation of resident brain cells such as microglia and the recruitment of infiltrating immune cells. Increasing evidence supports that plasticity of the myeloid cell lineage is determinant for the specific role of these cells on stroke outcome, from initiation and maintenance to resolution of post-ischemic inflammation. The aim of this review is to summarize some of the key characteristics of these cells and the mechanisms for their recruitment into the injured brain through interactions with platelets, endothelial cells and other leukocytes. Also, we discuss the existence of different leukocyte subsets in the ischemic tissue and, specifically, the impact of different myeloid phenotypes on stroke outcome, with special emphasis on neutrophils and their interplay with platelets. Knowledge of these cellular phenotypes and interactions may pave the way to new therapies able to promote protective immune responses and tissue repair after cerebral ischemia.

Intergroup Threat and Outgroup Attitudes

2013 ◽  
Vol 44 (5) ◽  
pp. 311-319 ◽  
Author(s):  
Marco Brambilla ◽  
David A. Butz
Keyword(s):  
Gay Men ◽  
Social Group ◽  
Welfare Recipients ◽  
Intergroup Attitudes ◽  
Social Policies ◽  
Intergroup Threat ◽  
Economic Threat ◽  
The Impact ◽  
General Climate

Two studies examined the impact of macrolevel symbolic threat on intergroup attitudes. In Study 1 (N = 71), participants exposed to a macrosymbolic threat (vs. nonsymbolic threat and neutral topic) reported less support toward social policies concerning gay men, an outgroup whose stereotypes implies a threat to values, but not toward welfare recipients, a social group whose stereotypes do not imply a threat to values. Study 2 (N = 78) showed that, whereas macrolevel symbolic threat led to less favorable attitudes toward gay men, macroeconomic threat led to less favorable attitudes toward Asians, an outgroup whose stereotypes imply an economic threat. These findings are discussed in terms of their implications for understanding the role of a general climate of threat in shaping intergroup attitudes.

Sign in / Sign up

Export Citation Format

Share Document