Detonation Research Articles

Identifying Hazardous Conditions for Rapid Compression Scenarios of Chemically Unstable Gases in Industrial Scaled Pipes

The polymeric industry handles Tetrafluoroethylene (TFE) as basic material for polymer (PTFE) and co- polymer (PCTFE) production. As a chemically unstable gas, it can react in an explosive way, without the presence of any other gases. Once initiated such an exothermic reaction can propagate through the pipe system of a plant and might lead to massive damages and/or fatalities. Especially after maintenance parts of the pipe systems can be filled with TFE, nitrogen or air at pressures up to atmospheric conditions whereas connected parts of pipes might still contain TFE at operating pressure state. Many of the regarding pipes are separated by ball valves, which allow a fast opening procedure. Thereby fast compression of the gas can occur and lead to a massive temperature increase which might induce unwanted reactions. Former tests in laboratory scale described by Meyer (2009) allowed an ignition of a TFE/air system by rapid compression only for a set of sharp defined boundary conditions. First tests in the lower industrial scale were done by Ferrero et al. (2013), where an ignition at typical industrial operating conditions was initiated. The results of the tests indicated that the critical achievable compression temperatures strongly depend on the setup and therefore on the pipe diameter as well. Therefore the necessity of further tests has been pointed out. The original setup presented by Ferrero (2013), which represents the smallest typical industrial size with an inner diameter of 1.125”, was modified to withstand an explosive decomposition reaction and to avoid a deflagration to detonation transition. Different safety concepts as burst discs and time controlled cut-off valves had been tested and evaluated to optimize the experimental setup for reproducible test conditions. This allowed the systematic investigation of the rapid compression of TFE–systems for the first time in the described scale without serious damages after an ignition. In the donor pipe always TFE at high pressure and in the receiving pipe TFE, nitrogen or air were present at an absolute pressure ranging from 500 Pa to atmospheric pressure.The scope was to generate a “hazard diagram” in which the ignition probability in dependence of donor (high) pressure and the receiving (low) pressure is shown. Hazardous conditions can easily be determined. A reference method for the maximum achievable temperatures of non-reacting gas systems was created using an air/air-system. Thus reactive TFE-systems could be evaluated regarding additional exothermic effects. The final hazard diagram demonstrates that there is no sharp limit between a “safe” state and an “ignition” for a TFE/air-system. Rather a transition range exists, which decreases with rising donor pressure. An increased temperature in this range, sometimes combined with small pressure peaks in the profile, indicates first partial restricted reactions near the end flange. The more it gets closer to the “ignition” transition the more traces like soot or undefined solid fractions were found. A TFE/nitrogen- and a TFE/TFE-system could not be ignited at all. A description of the experimental tests as well as a detailed explanation of the hazard diagram will be presented.

Kannjawou par Lyonel Trouillot

Reviews 233 discovery of love has somehow humanized him. Such things may happen in life, but not convincingly in this novel. Florida State University, emeritus William Cloonan Trouillot, Lyonel. Kannjawou. Arles: Actes Sud, 2016. ISBN 978-2-330-05875-3. Pp. 193. 18 a. An impoverished street serves as a microcosm of the whole in Trouillot’s new novel. Following a similar approach used by another Haitian author, Emmelie Prophète in Impasse Dignité (FR 86.6), Trouillot dissects the dynamics and dysfunction of his country via a focused study of a group of friends living in lack on the “rue de l’Enterrement.” Leading up to the local decaying cemetery, this street is not an altogether bad location to inhabit, we are told by Man Jeanne, the novel’s doyenne of sage advice and adages, since its presence and the tinkling sound of grave robbers toiling away in the night are helpful mortality reminders of just how soon all the street’s residents will join the ranks of the dead. The novel’s broader backdrop is a humanitarian occupation of Haiti by various international NGOs with numerous and equally damning references to the American Occupation of the country (1915–1934). Charlemagne Péralte’s contribution as a guerilla fighter during that period is lauded in the text and his photo prominently on display serves as inspiration for the more currently militant minded in the group. The band of five, as the clan is referred to, consists of the narrator, a self-described scribe whose penchant for studying life’s itineraries fuels the journal we are reading, his brother Popol, Wodné, and two sisters Sophonie and Joëlle. Following a brief sketch of the early years of the group’s friendship, the narrative quickly moves to the current status of young adulthood with its limited prospects for future success and overall sense of defeat: “Comment se révolter contre un ennemi qui change sans cesse de ton et de visage?” (21). To push back in some concrete way against the occupation, the friends form a cultural center in an alley, offering books, discussion, and wisdom as dispensed by the local, formally radical university professor, with whom the narrator has formed a bond via shared literature, despite their different class standings. Pivotal in the text is the neighborhood restaurant-bar, the Kannjawou, which serves as a dividing line between the rich NGO administrators who can afford to frequent it and the band of locals whose only member to enter does so through a wait staff door. A perfectly chosen metaphor of irony and class division, the term Kannjawou in creole connotes a vast celebration, a sharing, economically off limits to those of the rue de l’Enterrement in need of it most. The text’s chapters with their evocative style read easily and the panoply of characters and events that appear in its pages does not cease to intrigue: Halefort, the head grave robber arranges a mutually beneficial alliance with the local police while Julio, whose reluctant acceptance of his homosexuality deepens the narrative, walks fatalistically toward his encounters with paying army officers. As touched and concerned readers of this contemporary Haitian exposé, we are left in the end with the narrator’s own uncertainty regarding the future: “Quel soi-même on finit par être, au bout de quel parcours” (16)? University of Colorado Denver Linda Alcott Linguistics edited by Bryan Donaldson Anscombre, Jean-Claude, Évelyne Oppermann-Marsaux, et Amalia RodríguezSomolinos , éd.Médiativité, polyphonie et modalité en français: études synchroniques et diachroniques. Paris: PSN, 2014. ISBN 978-2-87854-609-5. Pp. 268. 17 a. Any utterance carries multiple levels of meaning beyond the core“message”itself, including a speaker’s attitude about the information conveyed, the reliability of the source of that information, and—in some cases—echoes of voices other than that of the speaker. These are the threads that unify the contributions to this volume, dedicated to intersections of three linguistic notions: médiativité, roughly a speaker’s indication of the source and reliability of information (“evidentiality” in the AngloSaxon literature); polyphonie, the presence in an utterance of voices or points of view other...

Histoire de la littérature française: voyage guidé dans les lettres du XIe au XXe siècle par Michel Brix

Reviews 193 Danticat et Laferrière d’une part, et de Naipaul et Kincaid d’autre part: “Is writing about home a cultural obligation or an act of opportunism for the expatriate writer?” (25) et “should publicly criticizing home be necessarily viewed as an act of treason in Caribbean diasporic writing?” (26). Dans le dernier chapitre, l’auteure voit dans la figure du bossale, l’esclave né en Afrique, et la nécessité de la survie dans le système colonial, l’origine de l’individualisme littéraire de ces écrivains. Ce livre aborde, avec expertise et une liberté de ton appréciable, des questions centrales pour la littérature caribéenne et postcoloniale mais aussi pour les critiques. Il aurait été intéressant de lire une auto-analyse de l’auteure sur ces questions qui touchent aussi le critique universitaire“renégat”ou non, pris entre un système universitaire, le marché des livres littéraires et universitaires et ses communautés d’appartenance. University of South Florida, St Petersburg Martine F. Wagner BRIX, MICHEL. Histoire de la littérature française: voyage guidé dans les lettres du XIe au XXe siècle. Louvain-la-Neuve: De Boeck, 2014. ISBN 978-2-80-418930-3. Pp. 375. 19,50 a. French students at the college level rely on survey-type books to supply historical, political, and biographical information for the texts that they read in their courses. However, these surveys are often dryly presented lists of facts and definitions that seem oddly dislocated from the source materials, and frankly dreary and unmemorable to our students. Brix’s book is a welcome alternative, and one that I would urge should be purchased by all French majors and minors in the first semester of studies and used throughout their four years in advanced courses. The book comes with an activation code for the ebook version—unfortunately valid for only one year—allowing for notes in the margins, highlighting of text, and many other interactive features. While the title may suggest that this book is best suited for survey courses alone, it lends itself quite well to courses focused exclusively on one genre (like French theater or poetry), on one particular theme (the“Moi,”for example), on one literary movement, on particular authors or concepts (such as vraisemblance or mise en abîme), or even courses devoted to political, religious or social history. The genius of this book is that Brix provides threads that one can follow throughout the course of French literary history. While these threads can be examined alone within a given time period in this chronological study, taken as a whole after one finishes the book, they weave a tapestry that slowly reveals the back and forth between past and present.While chronology provides helpful guideposts, Brix is not a slave to it. Readers are constantly reminded of the bigger picture, as Brix transports us backward in time to earlier influences, and forward to how point A leads to point B. Throughout, he injects intriguing anecdotes, and fascinating tidbits that together make the authors appear like characters in a novel. The ultimate thread that Brix weaves into the book, yet leaves dangling in the end, involves the slow march through time toward a literature of the Self—with Proust as the greatest model. Brix notes the proliferation of autobiography, memoir, and“autofiction ,”wherein“il est établi que se raconter, c’est non seulement une obligation, mais c’est aussi de l’art: l’écrivain qui se respecte doit mettre en scène son MOI” (355). He leaves us with a provocative question: has this navel-gazing not left French literature bereft of a much-needed return to an other-centeredness? Brix devotes the last few pages to this question, and adds, “Pourquoi lit-on? Pourquoi la littérature existet -elle?” (353). Waxing nostalgic, the enigmatic last line invites the reader to consider that French literature needs to return to a past glory:“On aurait bien besoin,aujourd’hui, d’un nouveau Balzac. Mais si—par bonheur—il existait, qui pourrait l’apercevoir?” (355). Given recent assaults on the humanities, the question concerning the relevance of literature—and his (perhaps...

5-叠氮基-1,2,4-三唑-5-乙酸(ATAA)的合成及热性能（英）

The title compound, 5-azido-1, 2, 4-triazolyl-5-acetic acid (ATAA), was synthesized for the first time by Sandmeyer-reaction in a mixed system (including sodium nitrite, sulfuric acid and sodium azide) from 5-amino-1, 2, 4-triazolyl-5-acetic acid. Its chemical structure was fully characterized via NMR, IR, MS and elemental analyses. Typical TG and DSC curves indicate the thermal behavior of ATAA includes one dehydrating crystal water stage, one melting stage and one obvious melting decomposition stage. The peak temperatures at each stage are 85.6 ℃, 168.0 ℃ and 177.9 ℃, respectively. In addition, a novel polynitro-azole energetic compound (5-azido-3-trinitromethyl-1H-1, 2, 4-triazole) was designed and calculated. The standard enthalpy of formation, the calculated density as well as the detonation velocity are 449.62 kJ·mol -1 , 1.91 g·cm -3 and 9096 m·s -1 , respectively.

Tsar Bomba detonated

Tsar Bomba detonated

Komputerowa symulacja działania głowicy bojowej pocisków rakietowych klasy Z-Z

Komputerowa symulacja działania głowicy bojowej pocisków rakietowych klasy Z-Z

3D cellular detonation in cylindrical channels

Gas detonation is a complex multidimensional process. In nature, the multidimensionality of detona� tion manifests itself in the cellular structure and in the spin. The cellular and spin detonations are formed due to instability of the burning zone behind the head shock wave, due to which small perturbations increase, and periodic spatial flows arise with trans� verse waves in the flow behind the head shock and with breaks of its front [1–4]. Previously, various authors investigated mainly numerically the formation of the 2D cellular detonation in the channels. In this case, the triple points in the spots of breaks of the 2D deto�

La ética del futuro arquitecto en el diseño y construcción de viviendas sustentables

Se considera que los alumnos cerca de egresar de sus estudios profesionales de arquitectura, deben estar conscientes y vivir la ética que corresponda al conjunto de principios y normas morales que regulan las actividades humanas, además de saber discernir lo que conviene, bueno o malo y a pesar de las dificultades que esto implique, debe tratar por todos los medios de apegarse a ese grupo de principios que regularán su conducta al interior y exterior del mercado laboral. Sin embargo observando su actuar cotidiano, se advierte que en las soluciones que este da a las preguntas que le fueron aplicadas en un cuestionario, se reveló la vinculación que estos guardan con la ética y los valores. Para llegar a concluir lo anterior surgieron estas cuestiones ¿Cuáles podrían ser las consideraciones que se debieran tener en cuenta para promover y desarrollar en los alumnos, la vivencia y práctica de la ética, un factor clave que detonará en el ejercicio cotidiano de la misma y que está, a su vez se reflejará al momento de proyectar viviendas sustentables?.Se consideró para dar solución a esos cuestionamientos de primera instancia, que toda participación de los profesionales y en este caso de la arquitectura debiera enmarcarse en la práctica y apego a la aplicación de los lineamientos establecidos por un Código de Ética que en el fondo estableciera los mínimos a los que un profesionista en el área y en cualquier otra, debiera sujetarse como una persona comprometida de manera integral, en todos las facetas de su vida cotidiana.

Spatial distribution of fragments of explosively loaded shells during flight

This paper correlated theoretically the effects if flight of an explosively loaded shell and the spatial distribution of fragments. The effect of spin of a shell is almost negligible on the spatial distribution of fragments, while the forward velocity of the shell at detonation affect both the velocity and the direction of emission of the fragments.

SPH and ALE Formulations for Fluid Structure Coupling

Simulation of Fluid Structure Interaction FSI, problems becomes more and more the focus of computational engineering, where FEM (Finite element Methods) for structural mechanics and Finite Volume for CFD are dominant. New formulations have been developed for FSI applications using mesh free methods as SPH method, (Smooth Particle Hydrodynamic). Up to these days very little has been done to compare different methods and assess which one would be more suitable. For small deformation, FEM Lagrangian formulation can solve structure interface and material boundary accurately; the main limitation of the formulation is high mesh distortion for large deformation and moving structure. One of the commonly used approach to solve these problems is the ALE formulation which has been used with success in the simulation of fluid structure interaction with large structure motion such as sloshing fuel tank in automotive industry and bird impact in aeronautic industry. For some applications, including bird impact and high velocity impact problems, engineers have switched from ALE to SPH method to reduce CPU time and save memory allocation. In this paper the mathematical and numerical implementation of the ALE and SPH formulations are described. From different simulation, it has been observed that for the SPH method to provide similar results as ALE or Lagrangian formulations, the SPH meshing, or SPH spacing particles needs to be finer than the ALE mesh. To validate the statement, we perform a simulation of a shock wave propagation generated by explosive detonation. For this simple problem, the particle spacing of SPH method needs to be at least two times finer than ALE mesh. A contact algorithm is performed at the fluid structure interface for both SPH and ALE formulations.

Against Écriture Féminine : Flaubert's Narrative Aggression in Madame Bovary

Against Écriture Féminine:Flaubert's Narrative Aggression in Madame Bovary Ashley Hope Pérez "Avec rage": Flaubert's Revenge "J'ai rempoigné la Bovary avec rage," Flaubert wrote to Louis Bouilhet two months after the end of his relationship with Louise Colet, the woman who had been lover, correspondent, and—perhaps most importantly—rival writer in Flaubert's eyes until the couple separated definitively in 1854.1 The letters to Colet, written over nearly a decade, attune us to the height of Flaubert's artistic aspirations and the extent of his insecurities. They also reveal the degree to which questions of aesthetic power and artistic identity become embroiled in Flaubert's problematic construction of the feminine, a construction that culminates in his writing of Madame Bovary as a portrait of female artistic failure. Throughout the letters, Flaubert expresses his desire to remake Colet in his image. "Je ne veux de toi, comme femme, que la chair. Que tout le reste donc soit à moi, ou mieux, soit moi, de même pâte et la même pâte," he writes, adding some months later, "Oh si je pouvais faire de toi ce que j'en rêve, quelle femme, quelle être tu serais!"2 Flaubert did not, however, get his wish. Although Colet's letters to Flaubert have been lost, the stylistic elements of her published works demonstrate her refusal to conform to the edicts and declarations he directed at her.3 Principal among these pronouncements was Flaubert's railing against the excessive effusiveness and fluidity that he associated with her womanhood. "Tu t'abîmes avec l'élément femelle," he warns, and he counsels elsewhere, "tu arriveras à la plénitude de ton talent en dépouillant ton sexe."4 Even more scathingly, he criticizes what he saw as her stylistic faults by accusing her of excessive femininity: "Il ne faut pas, quand on est arrivé à ton degré, que le linge sente le lait . . . comprime les seins de ton coeur, qu'on y voie des muscles et non une glande."5 Later, we [End Page 31] will see how Flaubert's focus on excess in Colet's writing—and her linen—points to his anxiety that there might be a whiff of milk from his pages as well. For now, though, Flaubert's basic message is plain: if Colet was to be any kind of writer, she ought to write like a man, preferably like Flaubert himself. Yet Colet continued, vexingly, to be a writer and not to be Flaubert. Failing to rewrite Colet or shape her aesthetic convictions after his own, Flaubert wrote Emma Bovary with a vengeance. Indeed, Janet Beizer argues persuasively that Madame Bovary is Flaubert's "most bitter note of revenge" to Colet, "his longest letter in a correspondence already officially ended."6 Written from the start as what Jacques Rancière calls the "embodiment of the wrong way," Emma the failed writer functions as a critical element in Flaubert's elaborate attempts at self-definition against "feminine" writing.7 If Flaubert permits a reading of Madame Bovary as "the portrait of an artist . . . as a young woman," as Naomi Schor suggests, this is nevertheless a degraded portrait strategically conceived so that more credit and acclaim can accrue to the male author.8 Put another way, Flaubert presents Emma as an incompetent writer so as to highlight the unique accomplishments of his narrative technique. Madame Bovary as a showpiece of originality, then, depends for its success on the denigration of a degraded representation of écriture féminine as literary practice and performance. "Les océans laiteux": Emma's Models The novel's thematic treatment of sentimental narratives—specifically as a force that destroys originality and artistic potential—is one of Flaubert's strategies for ridiculing the inferior literary company pursued by women, as exemplified by Emma. Flaubert first figures her bad taste and laughable fantasies in his depiction of her growing disillusionment with her marriage: "Emma cherchait à savoir ce que l'on entendait au juste dans la vie par les mots de félicité, de passion et d'ivresse, qui lui avaient paru si beaux dans les livres".9 This passage introduces the thread...

Susceptibility of Electro-explosive Devices to Microwave Interference

In this paper, the electromagnetic susceptibility of electro-explosive devices (EEDs) including their connection wires is assessed statistically. The electromagnetic coupling and the thermal power dissipation are modeled to determine the activation condition due to an excitation with an external electromagnetic field. The reception properties of the connection wires are obtained numerically and validated experimentally; variations in their geometry are considered by means of a Monte Carlo approach. The optimal coupling frequency and the probability of activation of a typical wired BED as function of the magnitude of the excitation are obtained. A detonation probability of 95 per cent is obtained for a wired EED illuminated with a 2447 V/m incident field.

Parameters for Attenuation and Suppression of Detonation Wave with Inert Particles

The method of gas detonation wave attenuation and suppression by chemically inert particles injection before the leading shock front is considered. Parameters and cell size of a steady detonation wave are calculated. The minimum mass fraction and total mass of particles and the characteristic size of the cloud, which are necessary for detonation wave suppression, are calculated. Methane-, Cyclohexane-, Hydrogen- and Silane-air mixtures with particles of W, WC, Al2O3, SiO2 and KCl are considered. Results of calculations quite good correspond to available experimental data. The process of suppression is more effective, if particles have high heat capacity and heat of melting. Among the particles under consideration Al2O3 and SiO2 particles are better for detonation suppression.Detonation limits for different chemical compositions of methane-air mixtures and mass fractions of SiO2 particles are calculated. An increase of particles concentration leads to increase of the lower and decrease of the upper detonation limit. If a mass fraction of condensed phase is high enough, detonation wave propagation is impossible.A steady detonation wave reflection from a rigid wall (D ? D reflection) in cyclohexane- and silane-air mixtures with SiO2 particles is considered. It is shown, that particles can drastically reduce pressure and temperature behind the reflected wave and therefore prevent crucial destruction of equipment.The efficiency of detonation wave suppression at different relations between fuel and oxidizer is calculated. Methane- and cyclohexane-air mixtures with Al2O3 particles are considered. It is shown, that for every particles concentration the value of cell size has a minimum, which corresponds to a fuel-rich chemical composition. It means that for this relation between fuel and oxidizer the efficiency of detonation wave suppression by particles injection has a maximum.

Explosion in an Exhaust Line of a Chemical Reactor

An explosion occurred in the exhaust line to the scrubber during a cleaning procedure with concentrated nitric acid in a chemical reactor. Previously the reactor was treated with methanol under reflux and afterwards rinsed with drinking water. The detonation destroyed completely a section of a PN 16 condensate pipe after a flame arrestor. Glass piping, several fittings and the flame arrestor were also severely damaged. Also windows were damaged in the production room. The aim of this paper is to outline the incident investigation involving: the determination of potential explosive substances or explosive atmosphere in the pipe; a systematic analysis of ignition sources; a definition of possible scenarios of the explosion causes and sequence; a plausibility assessment of the scenarios regarding the observed damage; an evaluation of the probability of the scenarios; and a proposal of safety concepts to avoid future incidents. The investigation involved the use of Differential Scanning Calorimetric measurements (DSC) and analytical procedures from different samples remaining in different parts of the equipment after the explosion. The most probable cause of the incident was the formation of methyl nitrate in the condensing line of the flame arrestor. The detonation was initiated by the heat produced by the reaction between condensed nitric acid and methanol. Lessons learnt were used to modify the process to improve its safety.

A note on the detonation of TNT

Whenever a non-reactive shock passes .through a system which is capable of undergoing an exothermic reaction, the high temperature and pressure in the shock front may start the chemical reaction, and it is possible that the heat evolved, under suitable conditions, map support the wave, and a self sustained stable shock propagate through the system. This shock wave maintained by the heat of the reaction constitutes a stable detonation wave. The equations of conservation of mass, momentum and energy, across the wave give the well known Rankine Huginiot equation. The formulation of an equation of state leaves the conditions behind the pure shook wave undetermined

Computer Implementations with 3D Simulations of Models for Quick Estimations of Fragments Trajectories, Penetrations and Safety Evaluations Due to Detonations of Explosives

Computer Implementations with 3D Simulations of Models for Quick Estimations of Fragments Trajectories, Penetrations and Safety Evaluations Due to Detonations of Explosives

Criterion of shock-wave initiation of detonation in solid explosives

The criteria of the shockwave excitation of deto� nation in solid explosives existing at present are reduced to experimentally established values of the critical parameters, with achievement of which partial or complete explosive transformation takes place in explosives. Such parameters are determined by fixing the presence or absence of explosive chemical trans� formations under the action of shortterm pressures (from submicroseconds to tens of microseconds) on explosives, which substantially exceed both the quasi� static and the dynamic durability of the explosives under investigation.

Remarks On Deformation In Snow With Residual Stress And Gravitational Force By Detonation Impact

Estimation of strain (deformation) and strain energy at the time of an explosion has been undertaken in the present investigation. A basic concept of explosive pressure which is required for the estimation of strain and strain energy has been drawn from the underwater explosion with suitable modification to the present studies. One of the most significant aspects of the present investigation is to augment the model by accounting it for gravitational force and residual stresses which are of realistic in nature. Studies consist of computational aspect by observing the variation of strain and strain energy with respect to material parameters such as Elastic modulus (E), poisons ratio (?), density (?), and flow parameters such as peak pressure (Pm), sound velocity (Vs), and length of snow slab (L). One of the interesting observation found in the computational aspect is, the deformation is found to decrease as the velocity of sound (Vs) in snow increases which appears to be strange but found factual. The model has been compared with the other existing papers in the literature and found that, the present model yields to better results. ABSTRAK: Anggaran regangan (canggaan) dan tenaga regangan pada masa letupan diambil kira dalam kajian ini. Konsep asas tekanan letupan yang diperlukan untuk anggaran regangan dan tenaga regangan diperolehi daripada letupan bawah air dengan pengubahsuaian yang sesuai dalam kajian terkini. Antara aspek penting dalam kajian ini adalah penambahan model dengan mengambil kira daya graviti dan tegasan sisa yang sebenar. Kajian terdiri daripada aspek pengiraan, dengan memerhatikan variasi regangan dan tenaga regangan terhadap parameter bahan seperti modulus anjal (E), nisbah Poisson’s (?), ketumpatan (?), dan parameter aliran seperti tekanan puncak (Pm), halaju bunyi (Vs), dan panjang papak salji (L). Antara pemerhatian menarik yang ditemui dalam aspek pengiraan ialah, canggaan didapati berkurangan ketika halaju bunyi (Vs) salji bertambah. Walaupun ini nampak asing, tetapi ianya terbukti benar. Model dibandingkan dengan kertas kerja lain dan didapati bahawa, model terkini memberikan keputusan yang lebih tepat.KEYWORDS: avalanche dynamics; fracture mechanics; detonation pressure

Characteristics, mechanism, and spatiality of neo-migrants' homeplace-based communities in China: A case study of Hubei Village, Guangzhou

Against the backdrop of rapid urbanization,homeplace-based communities accommodating rural migrants from the same origin areas have proliferated in China's metropolitan cities.This phenomenon has attracted a wide range of political concern and media attention.However,little scholarly attention has been devoted to such rural migrant enclaves from the perspective of the social space,and to what extent and in what way 'the power of place' imposes influences upon the migration process and the labor-market process of rural migrants remain poorly understood.Based on field study and qualitative method,this paper aims to probe into the evolution process,basic characteristics,formation mechanism,and spatiality of Hubei Village,a homeplace-based community located in the city of Guangzhou,in the context of rapid urbanization.Our findings reveal that Hubei Village in general has become specialized in economic structure,homogeneous in sub-ethnic composition,and diversified in social stratum since the advent of the reform and opening up,and that abundant production networks and recruitment channels embedded with native space connections engender this community an enclave of key social and cultural distinction from surrounding areas.Our results suggest that Hubei Village plays a key role in accumulating and retaining all kinds of sub-ethnic elements,e.g.capital,labor force,and identity.Specifically,Hubei Village provides a place for the circuit of Hubei migrants' economic capital,for upward mobility of hubei labor migrants,and for integration of Hubei migrants into the host society of detonation cities.Our results further indicate that Hubei Village is a product of interrelated and interwoven forces at varied geographical scales,including market,institutional,and regional-level factors on a macro scale,factors related to urban expansion and infrastructure development on a meso scale,and factors related to competitive edges of Hubei garment factories,entrepreneurial spirit of Hubei migrants,and active response of local community on a micro scale.Based on our empirical study,we make a conclusive remark that homeplace-based communities,as new urban social spaces facilitated by grass-root efforts,make great contributions to the integration of neo-migrants in China's metropolitan cities.Therefore,governments should be cautious to carry out the wholesale demolition of homeplace-based communities,and should reconsider existing redevelopment policies toward urbanized villages.

A Demolition Experiment of a Scaled Model for a Concrete Box Girder Bridge

Along with series of concrete block experiments, a demolition experiment was conducted for a scaled concrete box girder bridge to investigate collapse and blast behavior. Tri nitro toluene (TNT), the standard explosive for strength was adopted as concussion charge. The result show that demolition was caused by not only direct detonation pressures at charging spots but also blast pressures at inner wall of concrete box girder.