Imperfection Sensitivity: A Review of Buckling Behavior of Cones, Cylinders, and Domes

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
O. Ifayefunmi ◽  
J. Błachut
Keyword(s):  
Research Effort ◽  
External Loading ◽  
Imperfection Sensitivity ◽  
Buckling Strength ◽  
Buckling Behavior ◽  
Different Types ◽  
Theoretical Predictions ◽  
Initial Geometric Imperfections ◽  
Insight Into

It is generally accepted that the presence of imperfections in pressure vessel components can significantly reduce their buckling strength. In fact, the discrepancies between theoretical predictions and experimental results have been attributed to various kinds of existing and unavoidable imperfections. This is not a new problem but despite of substantial research effort in this area over the recent decades, it is far from being satisfactorily resolved. This review provides insight into the past findings and current activities related to the role of different types of imperfections on the buckling strength. It aims to contribute to a better understanding of the influence of imperfections on the structural stability of cones, cylinders, and domes when these are subjected to external loading conditions. The review concentrates not only on the prominent role of initial geometric imperfections of the shell's generator but also on less known defects. This includes uneven axial length of cylinders, eccentricities, and nonuniformities of applied load, inaccurately modeled boundary conditions, corrosion of the wall, influence of material discontinuity or crack, and effect of prebuckling deformation. The study examines: (i) how the data were obtained (analytically, experimentally, and/or numerically), (ii) the type of material from which the shell structures were made, and (iii) the importance of findings of the previous works. Metallic and composite components are considered.

Robots in recycling and disassembly

2019 ◽  
Vol 46 (4) ◽  
pp. 461-466 ◽  
Author(s):  
Robert Bogue
Keyword(s):  
Research Effort ◽  
Electronic Waste ◽  
Waste Recycling ◽  
Content Type ◽  
Research Activities ◽  
Wide Range ◽  
Electronic Waste Recycling ◽  
Product Disassembly ◽  
Insight Into

Purpose This paper aims to illustrate the growing role robots are playing in recycling and product disassembly and provide an insight into recent research activities. Design/methodology/approach Following a short introduction, this first considers robotic waste sorting systems and then describes two systems for the disassembly of electronic products. It then provides details of some recent research activities. Finally, brief conclusions are drawn. Findings Robotic systems exploiting artificial intelligence combined with various sensing and machine vision technologies are playing a growing role in the sorting of municipal and industrial waste, prior to recycling. These are mostly based on delta robots and can achieve pick rates of 60-70 items/min and be configured to recognise and select a wide range of different materials and items from moving conveyors. Electronic waste recycling is yet to benefit significantly from robotics although a limited number of systems have been developed for product disassembly. Disassembly techniques are the topic of a concerted research effort which often involves robots and humans collaborating and sharing disassembly tasks. Originality/value This provides an insight into the present-day uses and potential future role of robots in recycling which has traditionally been a highly labour-intensive industry.

Effects of External Loading on the Morphology of the Yielded Regions in Trabecular Bone Predicted by FEA

2008 ◽  
Author(s):  
Xiutao Shi ◽  
Xiang Wang ◽  
Glen L. Niebur
Keyword(s):  
Trabecular Bone ◽  
High Stress ◽  
Tissue Level ◽  
External Loading ◽  
Trabecular Architecture ◽  
Mineral Density ◽  
Age Related ◽  
Insight Into ◽  
Increased Susceptibility

Osteoporosis is an age-related skeletal condition characterized by low bone mineral density and deterioration of the trabecular architecture leading to increased susceptibility to fracture [1]. Wolff hypothesized that trabecular architecture adapts to have its principal material axes aligned with the principal loading directions. Regions of experimentally labeled trabecular microdamage correspond to areas of high stress and strain calculated from FEA [2]. Studying the morphology of numerically predicted regions of tissue level yielding might provide insight into the role of trabecular architecture in the strength of trabecular bone.

scholarly journals Getting into position: the catalytic mechanisms of protein ubiquitylation

2004 ◽  
Vol 379 (3) ◽  
pp. 513-525 ◽  
Author(s):  
Lori A. PASSMORE ◽  
David BARFORD
Keyword(s):  
Protein Interactions ◽  
Regulatory Elements ◽  
Substrate Selection ◽  
Protein Protein Interactions ◽  
Different Types ◽  
Catalytic Mechanisms ◽  
Cellular Pathways ◽  
Ubiquitin Conjugating Enzymes ◽  
Insight Into

The role of protein ubiquitylation in the control of diverse cellular pathways has recently gained widespread attention. Ubiquitylation not only directs the targeted destruction of tagged proteins by the 26 S proteasome, but it also modulates protein activities, protein–protein interactions and subcellular localization. An understanding of the components involved in protein ubiquitylation (E1s, E2s and E3s) is essential to understand how specificity and regulation are conferred upon these pathways. Much of what we know about the catalytic mechanisms of protein ubiquitylation comes from structural studies of the proteins involved in this process. Indeed, structures of ubiquitin-activating enzymes (E1s) and ubiquitin-conjugating enzymes (E2s) have provided insight into their mechanistic details. E3s (ubiquitin ligases) contain most of the substrate specificity and regulatory elements required for protein ubiquitylation. Although several E3 structures are available, the specific mechanistic role of E3s is still unclear. This review will discuss the different types of ubiquitin signals and how they are generated. Recent advances in the field of protein ubiquitylation will be examined, including the mechanisms of E1, E2 and E3. In particular, we discuss the complexity of molecular recognition required to impose selectivity on substrate selection and topology of poly-ubiquitin chains.

scholarly journals Probing Shells Against Buckling: A Nondestructive Technique for Laboratory Testing

2017 ◽  
Vol 27 (14) ◽  
pp. 1730048 ◽  
Author(s):  
J. Michael T. Thompson ◽  
John W. Hutchinson ◽  
Jan Sieber
Keyword(s):  
Lateral Displacement ◽  
Experimental Tests ◽  
Volume Control ◽  
Imperfection Sensitivity ◽  
Nondestructive Technique ◽  
Experimental Procedure ◽  
Buckling Behavior ◽  
Highly Nonlinear ◽  
Structural Specimen ◽  
Insight Into

This paper addresses testing of compressed structures, such as shells, that exhibit catastrophic buckling and notorious imperfection sensitivity. The central concept is the probing of a loaded structural specimen by a controlled lateral displacement to gain quantitative insight into its buckling behavior and to measure the energy barrier against buckling. This can provide design information about a structure’s stiffness and robustness against buckling in terms of energy and force landscapes. Developments in this area are relatively new but have proceeded rapidly with encouraging progress. Recent experimental tests on uniformly compressed spherical shells, and axially loaded cylinders, show excellent agreement with theoretical solutions. The probing technique could be a valuable experimental procedure for testing prototype structures, but before it can be used a range of potential problems must be examined and solved. The probing response is highly nonlinear and a variety of complications can occur. Here, we make a careful assessment of unexpected limit points and bifurcations, that could accompany probing, causing complications and possibly even collapse of a test specimen. First, a limit point in the probe displacement (associated with a cusp instability and fold) can result in dynamic buckling as probing progresses, as demonstrated in the buckling of a spherical shell under volume control. Second, various types of bifurcations which can occur on the probing path which result in the probing response becoming unstable are also discussed. To overcome these problems, we outline the extra controls over the entire structure that may be needed to stabilize the response.

scholarly journals The Role of Public-Private Partnerships in Higher Education How Tertiary Institutions in emerging Economies benefit from Public-Private Partnerships

2017 ◽  
Vol 2 (1) ◽  
pp. 1-7
Author(s):  
Ronak Warasthe
Keyword(s):  
Higher Education ◽  
Emerging Economies ◽  
Tertiary Education ◽  
Added Value ◽  
Public Private Partnerships ◽  
Tertiary Institutions ◽  
The Past ◽  
Different Types ◽  
Insight Into

Abstract The number of Public-Private Partnerships in the education sector is growing in developing and emerging economies. Traditionally governments are the main financial contributor to education however, the involvement of the private sector is an increasing one. While more established in primary and secondary education, PPPs in tertiary education are a phenomenon rather slowly growing in the past decades (Patrinos, Barrera-Osorio, & Guaqueta, 2009). There are various concepts of PPPs in higher education each targeting different goals. In order to give an insight into different types of PPPs, the typology according to Mabizela has been briefly displayed and the case of a PPP in Namibia is given. The framework of the partnership was compiled to give an outlook on the practicability of partnerships. The paper exemplifies that both partners within a PPP can benefit from the added value they may generate for their target group. Thus, the benefit depends on quality, relevance and execution of the partnership.

scholarly journals Tłumacz-polemista. Zderzenie paradygmatów w pierwszym polskim wydaniu Orientalizmu Edwarda Saida

2020 ◽  
pp. 116-142
Author(s):  
Weronika Szwebs
Keyword(s):  
Cultural Studies ◽  
Main Text ◽  
Doctoral Thesis ◽  
Critical Attitude ◽  
Additional Information ◽  
Different Types ◽  
The Moment ◽  
Insight Into

Translator as Polemicist: The Clash of Paradigms in the First Polish Edition of Said’s Orientalism The article analyzes the paratextual activity of Witold Kalinowski, the author of the first Polish translation of Edward Said’s Orientalism (1991), paying special attention to his polemical remarks and their relation to the vision of scientific, theoretical discourse. The translator does not strive for invisibility. On the contrary, he uses footnotes and brackets inserted in the main text to comment on different aspects of Said’s work. He signals problems ensuing from the differences between languages and cultures, explains the nature of linguistic difficulties and justifies his own solutions. He also takes on the role of editor and commentator, explaining Said’s allusions, supplementing the discussion with additional information, anticipating readers’ doubts about certain facts that might sound suspicious, and even inserting bracketed additions and clarifications which suggest that the original is unclear or imprecise. Finally, Kalinowski overtly expresses his polemical attitude: he provides certain parts of Said’s discussion with sic! annotation (thus suggesting that the author is wrong) and adds footnotes where he argues with what he sees as the author’s dubious and far-fetched interpretations. The Translator’s Note gives certain insight into the nature of the disagreement between the author and the translator. Explaining why Orientalism is a difficult book to translate, Kalinowski enumerates its troubling features: the combination of different types of discourse and the large number of polemical accents, due to which the book is not fully scientific. The moment of the book’s publication might suggest that such a qualification could have been a result of the then scarce presence of poststructuralist thought and cultural studies in the Polish humanities. However, the analysis of Witold Kalinowski’s articles as well as his doctoral thesis from the 1980s shows both his awareness of the theoretical currents that influenced Orientalism and his critical attitude towards Marxist thought. It is the aversion to the Marxist-inspired interpretations – both Kalinowski’s personal methodological conviction and a widespread attitude in the early post-communist Poland – that seems to be the reason of the clash in the first Polish translation of Said’s work.

The Role of Technology in the Historical Development of Libraries Pre-Automation

2013 ◽  
pp. 21-37
Keyword(s):  
Historical Development ◽  
Library Services ◽  
Important Indicator ◽  
Different Types ◽  
Visual Technologies ◽  
Insight Into

This chapter examines the role of five different types of technology that have impacted libraries pre-automation: card catalogue, the telegraph and telephone, the phonograph and other audio visual technologies, microfilm, and punched cards. These technologies were used to varying degrees by librarians to improve organizational efficiencies and provide services to patrons. Only one of these technologies is specific to libraries – the card catalogue. Its development is an important indicator for understanding what it was past librarians valued. In a similar manner, how the remaining technologies were incorporated, or not incorporated as the case may be, into library services provides insight into what librarians felt was most important in providing services to patrons.

scholarly journals Targeting the Immune Microenvironment in Lymphomas of B-Cell Origin: From Biology to Clinical Application

Cancers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 915 ◽  
Author(s):  
Mulder ◽  
Wahlin ◽  
Österborg ◽  
Palma
Keyword(s):  
B Cell ◽  
Immune Cells ◽  
Clinical Results ◽  
Lymphocytic Leukemia ◽  
Inflammatory Microenvironment ◽  
Different Types ◽  
Survival And Growth ◽  
Characteristic Features ◽  
Insight Into

In lymphomas of B-cell origin, cancer cells orchestrate an inflammatory microenvironment of immune and stromal cells that sustain the tumor cell survival and growth, known as a tumor microenvironment (TME). The features of the TME differ between the different lymphoma types, ranging from extremely inflammatory, such as in Hodgkin lymphoma, to anergic, leading to immune deficiency and susceptibility to infections, such as in chronic lymphocytic leukemia. Understanding the characteristic features of the TME as well as the interactions between cancer and TME cells has given insight into the pathogenesis of most lymphomas and contributed to identify novel therapeutic targets. Here, we summarize the preclinical data that contributed to clarifying the role of the immune cells in the TME of different types of lymphomas of B-cell origin, and explain how the understanding of the biological background has led to new clinical applications. Moreover, we provide an overview of the clinical results of trials that assessed the safety and efficacy of drugs directly targeting TME immune cells in lymphoma patients.

scholarly journals A Case Of Atypical Gastric Carcinoma With Osteoclast Like Giant Cells

2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Rahul Pandit ◽  
Irina Danilova
Keyword(s):  
Immune Reaction ◽  
Epigastric Pain ◽  
Neoplastic Transformation ◽  
Tendon Sheath ◽  
Giant Cells ◽  
Different Types ◽  
Skeletal Neoplasms ◽  
Caucasian Female ◽  
Insight Into

Out of all the different types of neoplasms affecting the stomach, gastric carcinomas with Osteoclast-like Giant Cells (OGC) is one of the most uncommon. Although OGC are typically found in osseous neoplasms and tumors of the tendon sheath, few cases of extra-skeletal neoplasms with OGC have been documented. These typically involve organs such as the pancreas, gall-bladder, kidney, and breast. Even though the role of OGC in histogenesis of such tumors still remains unclear, their presence in extra-osseous neoplasms may indicate a certain level of immune reaction of the host towards the neoplastic transformation of normal tissue. We report a case of a 70-year-old Caucasian female hospitalized for evaluation of epigastric pain. Further examinations including endoscopy and biopsy of the stomach revealed gastric adenocarcinoma with OGC. This report also provides a brief insight into the possible immune reaction in such neoplasms

Studien zum Beulverhalten von eng ringversteiften Kreiszylinderschalen unter Axialdruck/Studies on the buckling behavior of closely ring-stiffened cylindrical shells subjected to axial compression

Bauingenieur ◽  
2016 ◽  
Vol 91 (10) ◽  
pp. 401-409
Author(s):  
Hartmut Pasternak ◽  
Andreas Jäger
Keyword(s):  
Storage Capacity ◽  
Thin Plates ◽  
Stiffened Shells ◽  
Axial Buckling ◽  
Buckling Behavior ◽  
Different Types ◽  
Buckling Failure ◽  
Thin Walled ◽  
Stiffened Cylindrical Shells ◽  
Insight Into

Der moderne Stahlbau ist geprägt vom Streben nach effizienten Materialeinsatz und Nachhaltigkeit. Einen Beitrag dazu liefern ringversteifte Behälter, bei denen dünnwandige Bleche und kräftige Ringsteifen zu einem Leichtbauwerk kombiniert werden. Die Bleche zwischen den Ringsteifen sind stark axialbeulgefährdet, jedoch wird die Beulgefährdung durch die Steifen deutlich reduziert. In diesem Aufsatz wird neben einem Ausflug in die Behälterbaupraxis ein Beispiel für dünnwandige, ringversteifte Tanks der Biogasindustrie diskutiert und einem unversteiften Behälter gegenübergestellt. Im Anschluss werden der traglaststeigernde Einfluss der Ringversteifung auf das Axialbeulverhalten der Bleche zwischen den Steifen vorgestellt und Einsparpotenziale aufgezeigt.   Abstract Modern steel construction is greatly influenced by the pursuit of building material efficient and sustainable structures. Ring-stiffened shells, that are built as a combination of thin plates with strong ring stiffeners, contribute to this goal. The plates are prone to failure by axial buckling. However, the ring stiffeners greatly reduce the susceptibility to a loss of stability by axial buckling failure. In this article an insight into different types of tank constructions is provided. An example of a very thin walled tank, typical in the biogas industry, is discussed and compared to a non-stiffened variant of the same storage capacity. The beneficial effect of the ring stiffeners on the bearing capacity of the plates between the stiffeners and potential material savings are discussed.

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