Добірка наукової літератури з теми "Explosion Phenomenon - Overview"

An explosion is defined as a large-scale, rapid and sudden release of energy. Explosions, such as a bomb explosion within or immediately nearby a building and a gas-chemical explosion, can cause catastrophic damage on the building's frames, collapsing of walls, blowing out of large expanses of windows, and shutting down of critical life-safety systems. In fact, an explosion may result in large dynamic loads, greater than the original design loads, of many structures. Blast phenomenon and blast efforts have been made during the past several decades to develop methods of structural analysis and design to resist blast loads. The analysis and design of structures subjected to blast loads require a detailed understanding of blast phenomena and the dynamic response of various structural elements. This paper introduces different methods to estimate blast loads, also presents a comprehensive overview of the effects of explosion on RC structures.

Purpose The purpose of this paper is to provide a critical overview of the recent phenomenon of outward foreign direct investment (OFDI) from China, from a more macro and historical perspective. Design/methodology/approach The paper critically reviews the extant literature and re-assesses available data on OFDI from China. Findings It is argued that despite the explosion of academic interest the phenomenon was neither unpredicted nor sudden. Originality/value The paper also argues that OFDI from China is not yet so important and neither presents insurmountable challenges to the established literature on FDI.

An explosion is an unwanted phenomenon that may be caused accidentally or intentionally. It may be occurred within or near the structure that causes massive damage to the same. An explosion becomes disastrous when the structural elements collapse partially or totally. Many works have been made to grow the techniques/methods of blast resistance structures. A detailed understanding is required for blast load and its effect on the several structural members in terms of dynamic responses to analyze and design a safe engineering structure. Further, in this article, a comprehensive overview of a systematic approach for the analysis of structure under blast load has been presented. For the computation of blast load, different types of empirical relations are available, which are in the pattern of pressure-time functions. Here, the same is represented concisely with an easier way of understanding. Prediction of blast load by the empirical, semi-empirical, and numerical method has been presented. Modelling of blast load for various numerical simulation techniques and material models are also described here for modelling the advanced structural material that may mitigate the blast response of the structure as per the Hydrocodes.

Advances in data science, such as data mining, data visualization, and machine learning, are extremely well-suited to address numerous questions in the organizational sciences given the explosion of available data. Despite these opportunities, few scholars in our field have discussed the specific ways in which the lens of our science should be brought to bear on the topic of big data and big data's reciprocal impact on our science. The purpose of this paper is to provide an overview of the big data phenomenon and its potential for impacting organizational science in both positive and negative ways. We identifying the biggest opportunities afforded by big data along with the biggest obstacles, and we discuss specifically how we think our methods will be most impacted by the data analytics movement. We also provide a list of resources to help interested readers incorporate big data methods into their existing research. Our hope is that we stimulate interest in big data, motivate future research using big data sources, and encourage the application of associated data science techniques more broadly in the organizational sciences.

After a long period of relatively low interest, science related to effects in the Extreme Ultraviolet (EUV) spectrum range experienced an explosive boom of publications in the last decades. A new application of EUV in lithography was the reason for such a growth. Naturally, an intensive development in such area produces a snowball effect of relatively uncharted phenomena. EUV-induced plasma is one of those. While being produced in the volume of a rarefied gas, it has a direct impact onto optical surfaces and construction materials of lithography machines, and thus has not only scientific peculiarity, but it is also of major interest for the technological application. The current article provides an overview of the existing knowledge regarding EUV-induced plasma characteristics. It describes common, as well as distinguishing, features of it in comparison with other plasmas and discusses its interaction with solid materials. This article will also identify the gaps in the existing knowledge and it will propose ways to bridge them.

Concrete has traditionally been considered as a material with favourable fire resistance. The development of modern concretes with low permeability has, however, resulted in the increased occurrence of spalling when exposed to fire. Recent fire damage in South Africa during the riots in July 2021 resulted in such damage. This paper presents an overview of explosive spalling of concrete in fire, recent local observations, and developments in the field. It is shown that various (often interrelated) factors influence the susceptibility of concrete to spall in fire, and that much research is still needed to fully understand the phenomenon and, specifically, how to accurately predict its occurrence. Recent observations in South Africa support conclusions in the literature that, as an accidental loading case or as life-safety performance criteria, overall structural integrity is rarely compromised. However, as the use of higher concrete grades increases, the relevance of this risk should be considered by practising engineers.

Abstract The aim of this contribution is to provide an overview of the calculation procedures of risk analysis, that is, the effects and consequences of pool fires. Fires and explosions are the most significant and most common causes of damage to equipment and of injuries and death in industry. Damages are a direct consequence of the generated heat flux. Mathematical tools for the prediction of heat flux at a distance can be divided into four classes: semi-empirical models, field models, integral models and zone models. Semi-empirical modeling is a relatively simple technique providing models predicting heat flux at a distance. There are two types of semi-empirical models: point source models and surface emitter models. By their nature, semi-empirical models depend strongly on experimental data. Correlations are able to describe the general features of a fire. Semi-empirical models are ideal for routine hazard assessment purposes because they are mathematically simple, and hence easily understood. However, if more models describing the same phenomenon are available, significant differences in the heat flux prediction can be expected. In this contribution, differences in the prediction of the heat flux from pool fires are discussed.

The introduction to the special issue of Methis on Estonian environmentalism provides an overview of the phenomenon of environmentalism and its spread across political periods, economic formations, and regions. The essay starts by contextualising the central concepts of the issue, ‘environmentalism’ and its possible translation into Estonian as ‘keskkondlus’, and its relationship with the concept of ‘nature’. At the end of the 1980s, amidst a deepening awareness of environmental crisis, some authors announced ‘nature’ to have met its end. While this end has become widely accepted within environmental discourse, the approach clashes with the traditional thinking about the beauty of nature and its strong bonds with national identities. To foster discussion and to bridge the discursive and ideological gap between the two perceptions, the authors of the articles use the concept as an umbrella term for both paradigms. The second part of the introductory article discusses East European environmentalism, drawing attention to the research into erroneous assumptions regarding the lack of environmental activism within the Soviet Union. Before its brief heyday in the 1980s, East European environmentalism was hidden within economy, policy, society and culture. However, its roots went deeper, reaching back to 18th- and 19th-century thought, to Baltic German – and later Estonian – early voluntary associations and the value seen in the homeland and its natural objects. The founding of animal and nature protection societies in the late 19th century was an early practical outcome, and similar thought became pronounced in print culture. In early 20th century, several nature protection areas were established, and people became avid consumers of popular science journals – an interest that would continue throughout the Soviet period. The 1970s saw an environmental movement to protect the wetlands of Estonia which were in danger of being drained. Throughout the 20th century, also fiction reflected the prevailing views of nature and emerging concerns about the environment. The issue’s opening article by Ulrike Plath and Kaarel Vanamölder takes us back to the 17th century to demonstrate the possibility of climate movements more than three centuries ago. This is followed by Karl Hein’s case study that depicts in detail the emergence of animal protection in Estonia a hundred years ago in the context of local and regional history. The next four articles focus on different aspects of environmental movements in the Soviet period. Elle-Mari Talivee retells the story of the peculiar character of Atom-Boy created by the childrens’ author Vladimir Beekman who depicts in this form the various developments in the Soviet nuclear industry. This example from children’s literature is paralleled by similar environmental concerns expressed in visual arts, as outlined in Linda Kaljundi’s article. In a more theoretical take on liberal and autocratic environmental protection, Viktor Pál discusses the Soviet propagandistic use of environmental issues. Olev Liivik contextualises the protests against phosphorite mining in the 1970–80s within the wider trends in the Soviet Union, including the practice of sending letters of complaint to the media, and the various waves of environmental dissent. The discussion of a more compact case of the so-called Green Cycling Tours by Tambet Muide demonstrates the same increasingly oppositional stance that took hold in the 1980s. Regarding the post-Soviet era, Tõnno Jonuks, Lona Päll, Atko Remmel and Ulla Kadakas analyse the various conflicts that have emerged around natural and cultural objects protected by law since the 1990s. In the freestanding article of the issue, Raili Lass writes on interlinguistic and intersemiotic procedures of translation in the theatre but, as our introductory essay suggests, points of convergence may be found here with the discussion of staging of conflicts in environmental protection. In the “Theory in Translation” section Timothy Morton’s classic discussion of environmentalism is published in Ene-Reet Soovik’s translation, accompanied by introductory remarks from the translator and Kadri Tüür. The final part of the issue’s introduction offers a comparative and interdisciplinary take on the themes discussed. The revelatory nature of historical events of any era, especially natural disasters or the conditions of their unfolding, uncovers the socio-environmental relations that push people to respond. Whether or not such responses become environmental movements depends on the context that either recognises or ignores human embeddedness in the environment. Searching for such parallels connects 21st century climate activism and 17th century upheavals, animal protection in the 1920s and a hundred years later. The Soviet period allows a simultaneous scrutiny of both the limited and ideological take on the apparent lack of Soviet environmentalism as well as the methodological challenges of finding the footprints of hidden awareness and activism. Unearthing this from literature, art and the restrained presence of expert voices also provides an explanation to the sudden explosion of activism in the 1980s. The silence of the next decades further proves that there is nothing obvious in the ways in which environmentalism can take hold of society, which demands precise and detailed inquiry such as provided by the authors of this special issue.

In spite of extensive research and development to prevent and mitigate dust explosions in the process industries, this phenomenon continues to represent a constant hazard to industries including manufacturing, using and handling of combustible dust material. Lack of fundamental methods in predicting the explosion severity characteristics and real dust cloud structure are recognized as a major obstacle in predicting the course and consequences of dust explosion in practice. This present paper discusses the influent factors affecting the explosion severity of the dust clouds in order to promote the advanced development for dust explosion. In addition, the impact of inerting on dust properties by using nitrogen or carbon dioxide to a level which the dust cloud can no longer propagate a self–sustained flame would also be explored. Key words: Dust explosion protection and mitigation; explosion severity; inerting

Given the focal role that group and team meetings play in shaping employees’ work lives (and schedules), the scarcity of conceptual and empirical attention to the topic in extant organizational psychology research is a major oversight that stalls scientific understanding of organizational behavior more broadly. With the explosion of meetings in recent years, in part due to the COVID-19 pandemic, some even wonder why organizational psychology has not already figured out meetings from both a science and practice perspective. The purpose of this paper is to synthesize the extant literature on the science of workplace meetings and sort the works by identifying the key features of the meeting phenomenon. The five key features of workplace meetings identified include Leading, Interacting, Managing Time, Engaging, and Relating. We couch these features within a larger framework of how meetings are the intersection of collaboration in organizations and indispensable to organizational success. Against this conceptual backdrop, we reviewed a total of 253 publications, noting opportunities for future research and discussing practical implications. Plain Language Summary Given the focal role that group and team meetings play in shaping employees’ work lives (and schedules), the scarcity of conceptual and empirical attention in extant organizational psychology research is a major oversight that stalls scientific understanding of organizational behavior more broadly. With the explosion of meetings that has occurred in recent years, in part due to the COVID-19 pandemic, some even wonder why organizational psychology has not already figured out meetings from both a science and practice perspective. The purpose of this paper is to review the literature on the science of workplace meetings by identifying the core features of the phenomenon and sorting the extant literature along these features. The five core features identified include leading, interacting, managing time, engaging, relating. We couch these features within a larger framework of how meetings are the intersection of collaboration in organizations and a major key to organizational success. Against this conceptual backdrop, we reviewed a total of 253 publications, noting opportunities for future research and discussing practical implications. We conclude our review with an overview of the special issue on workplace meetings, which is an overt attempt to launch research that will fill the theoretical and conceptual gap in the science of meetings.

Granular and porous materials based protective layers have proven to be very good shock absorbing medium. Although sand material is widely used (as sand bags) till date in civil and military applications as a blast mitigating medium, fundamental mechanism involved during the impact of shock/blast wave on sand layers is not well understood. This study presents experimental investigations on the impulsive response of sand to extreme loading conditions. A shock tube facility is used to generate a planar shock wave and further the facility is optimized to simulate the properties of a blast wave. This study is divided into three parts based on the type of loading imparted to the sand samples: Shock loading; Air-blast loading; Buried-blast loading. Part one discusses the performance of the sand barrier systems in attenuating the shock waves. The attenuation characteristics of various granular particles (coarse sand, fine sand, glass bead) are investigated by analyzing the reduction in peak overpressure while transmitting through the granular medium. The attenuating capability of the sand barriers has appreciably improved when the outer surfaces of the barriers are retrofitted with a geotextile layer. In the second part, a laboratory-scale experimental approach is presented for evaluating the effects of air-blast on the sand layers. Efforts have been made to study the stress wave propagation in loose and dense sand medium and its direct consequences on the vibrational response. Visualization of the sand deformation is possible with the help of a high-speed camera; displacement trajectories and strains contours are obtained through digital image correlation (DIC) analyses. Part two also reviews the applications of scaled air-blast study on buried pipelines. By using dimensional analysis procedure shock tube experimental results are scaled up to predict the real scale damage imparted to the buried pipes during an air-blast explosion. In addition, a three-dimensional finite element analysis of the test condition is simulated using ABAQUS/Explicit to authenticate the fidelity of the scaling laws. The third part discusses phenomenal aspects associated with the sand deposits when exposed to a buried blast explosion. The focus of this study is to understand the various events involved during the interaction of leading blast wave with the sand medium and characterizing the outburst sand-ejecta. The impulse and peak pressure imparted to the rigid target are evaluated using vertical pendulum and fast response pressure transducers. A parametric study involving different target stand-off distances (SoD) with varied burial depth (DoB) of the blast is presented. Sand ejecta does have a greater influence on the impulse at higher SoDs (>40 mm) and the maximum momentum transfer is observed when SoD to DoB ratio is 2.5.

The word media hype is often used as rhetorical argument to dismiss waves of media attention as overblown, disproportional and exaggerated. But these explosive news waves, as well as - nowadays - the twitter storms, are object of scientific research, because they are an important phenomenon in the public area. Sometimes it is indeed 'much ado about nothing' but in many cases these media storms have play an important role in political issues, scandals and crises. Twitter storms sometimes ruin reputations within hours. Although different concepts are used, such as media hypes, news waves, media storms, information cascades or risk amplification, all the studies in this book refer to the same process in which key events trigger a chain of reactions and interactions, building up huge news waves in the media or rapidly spreading social epidemics in the social media. This book offers the first comprehensive overview of this important topic. It is not only interesting for scholars and students in media and journalism, but also for professionals in PR and communication, crisis communication and reputation management.

Explosions can be considered to be the most devastating events in industry. Reasons that lead to such an event are often very complex. Nonetheless, the basic phenomenon is generally simple. To understand what leads to an explosion and how this can be prevented, the underlying physical and chemical processes as well as the basic steps that lead to an explosion are clarified. Practically a system of standards and regulations ensures a framework to avoid unwanted events. This together with typical sequence of events will be given and lead to a general overview of explosion process safety.

Arduengo et al., isolated the first ‘bottleable’ carbene, the first N-heterocyclic carbene (NHC) 1,3-di(adamantyl)imidazol-2-ylidene resulted to an explosion of experimental and theoretical studies of novel NHCs being synthesized and analyzed have huge practical significance. These compounds emerged as successful ligands for coordinating transition metals, the complexes with NHC show diverse applications in the field of catalysis and organic transformation, NHC as ligand to main group elements and their properties and applications. Here this chapter provides the concise overview of N-heterocycle carbene as an organocatalyst that provides different organic transformation on to a carbonyl group. The majority of the NHC catalyzed reactions are employed in the phenomenon of reversing the electrophilic character of carbonyl carbon to nucleophilic carbon (umpolung activity) on coordination suggests benzoin, Stetter and hydroacylation reactions. Also, non-umpolung activity of bis-electrophile α,β-unsaturated acylazoliums reaction with suitable bis-nucleophiles in the organic synthesis have been studied.

Metallic pressure vessels are of common use in the industrial field. They can contain either gases or liquefied gases. If a sudden pressure rise happens inside one of these vessels for any reason (human mistake, uncontrolled chemical reaction, BLEVE, rise in mass, explosion...), it can result in the bursting of the vessel. Though a pressure rise is relatively frequent, the response of the vessel to that sort of load cannot be easily forecasted, since the phenomenon is dynamic. Moreover, except from statistical studies, few experimental data are available on the topic. Therefore, an experimental study can help to understand the behavior of a pressurized enclosure in relation to such a solicitation. This paper analyzes the results of a set of experiments, that have been achieved in order to identify the mechanisms of a vessel rupture. The experimental device consists in a two-parts shock tube between which the sample, viz. a metallic plate, is set. This shock tube is fitted out with pressure gages. The plates are equipped out with strain and crack propagation gages. These sensors, in addition to a high velocity camera make possible the study of dynamic crack formation and fracture propagation on samples submitted to an explosion. Various classes of material with different ductilities have been tested. Moreover, the plate thickness influence has also been investigated. Flaws have been machined as external axial surface notches to produce and control cracking. Various solicitations have also been browsed: the loads were different kinds of explosions produced by the deflagration or the detonation of a stoichiometric hydrogen-oxygen mixture. Preliminary tests have shown a good reproducibility of the experiments. The loading amplitude (the pressure curves) and the shape of the plates after the operation, and especially the crack opening, are almost identical. These experiments have allowed to have a first overview of the role of the different input parameters on the plate behavior under load, and the way cracking occurs. The input parameters that have been monitored are the material ductility, the thickness of the samples and the kind of loading that is applied to them (i.e. different velocities deflagrations, detonations and so on). Output parameters are the strain rate of the plates and their cracking. Cracking is characterized by the size and the shape of the crack, its fracture facies and propagation velocity. In this paper, fracture behavior has been discussed with regard to the above mentioned parameters.

Abstract In Cold Spraying, bonding occurs when the impact velocities of particles exceed a critical value. This critical velocity depends not only on the type of spray material, but also on the powder quality, particle size and the particle impact temperature. For metallic materials, the critical velocity is in the range of 200 – 1200 m/s. In analogy with explosive welding, bonding in Cold Spraying is associated with adiabatic shear instabilities caused by high strain rate deformation during impact. Numerical and experimental methods are developed to investigate the influence of impact conditions and related phenomena on the coating quality. For a deeper understanding of impact phenomena and coating formation, the particle impact was modelled by using the finite element software ABAQUS/Explicit. The numerical analyses indicate shear instabilities localized to the particle surfaces, and thus provide a basis for the calculation of critical velocity in terms of materials properties and process parameters. In addition, modelling is used to obtain information about the effect of process parameters on the bonding quality. For most materials, high-strain-rate data are not available. For a quantitative analysis, therefore, the respective materials behaviour was investigated through individual spraying experiments, which were complemented by additional relevant experiments such as impact tests or explosive powder compaction. In this way, impact dynamics, bonding mechanism and critical velocities could be linked. This type of analysis was proved as a powerful tool to reduce the number of experiments for the optimisation of coating quality in Cold Spraying and also to provide a broader overview of the process.

In this paper, we introduce the overview of the requirements and the complementary information on the evaluation of containment functional failure frequency (CFF) in the revised version of “A Standard for Procedures of Probabilistic Risk Assessment of Nuclear Power Plants during Power Operation (Level 2 PRA) “[1] in Japan, which was developed and revised at the Level 2 PRA Subcommittee under the Atomic Energy Society of Japan (AESJ). Although the Level 2 PRA standard includes the evaluation of CFF and radiological source terms, we explain only the evaluation of CFF in this paper. In the evaluation of CFF, the physical response analysis and the probabilistic analysis are included as follows. The accident progression analysis is performed for each of the plant damage states, considering the operation status of mitigation systems, thermal-hydraulic behavior and core damage progression, and occurrences of some key events such as reactor pressure vessel failure. The containment event tree (CET) is developed classifying the accident progress in tree diagram. In the CET, some headings are arranged sequentially considering the accident progression. The headings correspond to the phenomena occurrence and the systems operation status, and a branch probability is assigned at each branch of heading. The branch probabilities of the phenomena are evaluated by either the Risk Oriented Accident Analysis Methodology (ROAAM) or the Decomposition Event Tree (DET) analysis considering the containment threats. The branch probabilities on the phenomena are set as the probability distributions, because the phenomena and the analysis have uncertainties. The branch probabilities on the systems operation are evaluated using the fault tree analysis and human error analysis. The containment functional failure modes are assigned at the end state of the CET considering the type of load against containment integrity. For the evaluation of the non-energetic load, the integral codes such as MELCOR [2], THALES-2 [3], and MAAP4 [4] etc. are used. On the other hand, various mechanistic codes are used for the evaluation of energetic phenomena such as steam explosion. The containment functional failure is judged by comparing the ultimate strength or the fragility of containment structure and the generated loads. After all, the CFF can be obtained by summing the frequency of containment functional failure mode. In the Level 2 PRA standard in Japan, the requirements in each evaluation process above are described. In addition, the technical background and the examples as the complementary information on each requirement are described in the Annex of the standard to help the application of the standard. In this revision, the body is revised to clarify the requirements on the quantification of the CET. The Annex is revised to incorporate the up-to-date information on severe accident research and severe accident management (SAM) measures. The updated information includes the melt stratification (OECD/MASCA project [5]), the steam explosion (SERENA project [6] and PULiMS/SES experiments [7]), the ex-vessel debris coolability (OECD/MCCI project [8]), debris jet breakup, the melt spreading, the coolability of the particulate bed, and the containment vessel (CV) fragility evaluation. Some future challenges are extracted from the lessons learned from the Fukushima Daiichi accident, such as development of the Level 2 PRA for the external hazard as earthquake and tsunami, quantification of impact on the containment integrity of hydrogen detonation in the adjacent buildings, and human error evaluation in the external hazard.

The strategy of the European Pressurized Water Reactor (EPR) to avoid severe accident conditions is based on the improved defense-in-depth approaches of the French “N4” and the German “Konvoi” plants. In addition, the EPR takes measures, at the design stage, to drastically limit the consequences of a postulated core-melt accident. The latter requires a strengthening of the confinement function and a significant reduction of the risk of short- and long-term containment failure. Scenarios with potentially high mechanical loads and large early releases like: high-pressure RPV failure, global hydrogen detonation, and energetic steam explosion must be prevented. The remaining low-pressure sequences are mitigated by dedicated measures that include hydrogen recombination, sustained heat removal out of the containment, and the stabilization of the molten core in an ex-vessel core catcher located in a compartment lateral to the pit. The spatial separation protects the core catcher from loads during RPV failure and, vice versa, eliminates concerns related with its unintended flooding during power operation. To make the relocation of the melt into the core catcher scenario-independent and robust against the uncertainties associated with in-vessel molten pool formation and RPV failure, the corium is temporarily retained, accumulated and conditioned in the pit during interaction with a sacrificial concrete layer. Spreading of the accumulated molten pool is initiated by penetrating a concrete plug in the bottom. The increase in surface-to-volume ratio achieved by the spreading process strongly enhances quenching and cool-down of the melt after flooding. The required water is passively drained from the IRWST. After availability of the containment heat removal system the steam from the boiling pool is re-condensed by sprays. The CHRS can also optionally cool the core catcher directly, which, in consequence, establishes a sub-cooled pool near-atmospheric pressure levels in the containment. The described concept rests on a large experimental knowledge base which covers all main phenomena involved, including melt interaction with structural material, melt spreading, melt and quenching, as well as the efficacy of the core catcher cooling. Besides giving an overview of the EPR core melt mitigation concept, the paper summarizes its R&D bases and describes which conclusions have been drawn from the various experimental projects and how these conclusions are used in the validation of the EPR concept.