bluuebunny/crossref_metadata_2025 huggingface dataset:
Texte, textualité et traitements automatiques
Authors: Anis Jacques
Published: June 2014

On montrera que le texte, défini au départ comme "message linguistique séquentiel et borné, matérialisé graphiquement et destiné à être lu par quelqu'un d'autre que le scripteur", fait coexister divers modes d'organisation, qui peuvent être séquentiels, arborescents, à étages, texturaux, réticulaires. On partira des représentations du texte induites par le traitement de texte. On examinera ensuite sommairement la textualité envisagée du point de vue de la construction du sens. Enfin on montrera comment l'hypertexte enrichit notre regard sur le texte.
L'évaluation des résultats de la levée d'ambiguïtés lexicales
Authors: Laporte Eric
Published: June 2014

Lexical disambiguation is a basic operation in natural language processing, but no satisfying solution to the problems it raises have been found yet. We survey the main differences between the various types of disambiguators, and we discuss the parameters involved in the assessment of the quality of their output. We show that usual methods of assessment of disambiguators do not take into account all of the most important parameters for applications, which does not contribute to directing research towards actual applications.
Grammaires électroniques et ambiguïtés
Authors: Greenfield-Cardey Sylviane
Published: June 2014

Currently, computerised spelling correction leaves much to be desired. A couple of examples from French demonstrate the difficulties involved : "les longues heures qu'elle a marché" and "elle fait généralement les marches(és)". How can there be recognition that, in the first sentence, march(é,es(és)) is a verb whilst in the second it is a noun ? Even more difficult, how can the correct ending be added to each of these words ? Furthermore, there is the problem of absent or incorrect diacritics to be dealt with. In this paper our objective is to present automatic and interactive grammars which solve these problems.
Analyse lexicale de l'ancien français
Authors: Bat-Zeev Shyldkrot Hava
Published: June 2014

Cet article a pour but d'exposer un projet qui consiste à développer des dictionnaires et grammaires électroniques de l'ancien français. On décrira d'abord les dictionnaires usuels de l'ancien français et les difficultés qui se posent à leur maniement. Puis, on énumérera un certain nombre de problèmes auxquels on se heurte lors de l'analyse et de l'étude de l'ancien français. La troisième et dernière partie sera consacrée aux différentes étapes prévues pour la réalisation de ce projet. On insistera, tout particulièrement, sur les divers volets du dictionnaire des verbes.
La première tentative d'uniformisation officielle de la nomenclature grammaticale en France (1910)
Authors: Boutan Pierre
Published: June 2014

The fight against the use of a grammatical metalanguage in primary schools seems to have been repeatedly stressed by official texts until the decree of 1910 which set the grammatical nomenclature. This decree was the outcome of a long series of compromises to which F. Brunot largely contributed. His ambition was to resist the persistent influence of the Grammaire générale of Port-Royal. For the first time, the decree gave a reference common both to primary and secondary education, and, from 1910 onwards, was to have a significant influence on grammar.
"Avez- vous Le Monde ?" Pour une analyse du dynamisme interactantiel des actes de parole
Authors: Nordahl Lund Steffen
Published: June 2014

Inspired by the semantic-pragmatic theory of polyphony, the article investigates the dynamics of indirect speech acts. A methodological approach within the framework of catastrophe theory makes it possible to overcome some difficulties formulated by O. Ducrot in his elaboration of the theory of polyphony.
Pronom, (més)usage d'un meta terme. Exemple de la langue 2
Authors: Briu Jean-Jacques
Published: June 2014

This is a comparative assessment of a corpus of five grammar textbooks and five German textbooks for French high-school students (fifth form) published between 1988 and 1994. These textbooks do not distinguish between the description of grammatical forms and their analysis. Up to eighteen different pronouns were listed ; however pronouns as a category are never defined, but always considered obvious or taken for granted. Their roles as substitutes is always more heavily adressed than their function as links. The disparity of metaterms is a great impediment to teaching, but the main weakness of these textbooks remains their lack of a coherent linguistic explanation.
Par delà les nuages de la terminologie. Quel métalangage au service de l'enseignement/ apprentissage des langues ?
Authors: Delbart Anne-Rosine
Published: June 2014

Il paraît difficile de nier que le recours au métalangage soit utile, voire nécessaire, dans l'enseignement/apprentissage des langues. Le propos du présent article se résume dès lors à une question : quel métalangage ? Pour y répondre, l'auteur de l'article a pris l'exemple des "temps" de l'indicatif. Trois partis s'offrent aux chercheurs-enseignants. (1) Garder la nomenclature traditionnelle, mais en la vidant de son sens. Inconvénient : la tendance des élèves à remotiver les étiquettes entraînera inévitablement des méprises concernant le fonctionnement des formes verbales. (2) Adopter une nomenclature qui s'en tienne à des évidences descriptives. Intérêt majeur : cette terminologie est facile à enseigner. En contrepartie, elle requiert un effort de mémoire de la part de l'élève, et la faculté, chez le maître, de renoncer à des habitudes bien ancrées. (3) Recourir à une nomenclature linguistiquement étayée. Encore f audra-t-il que le professeur se fraie un chemin dans le maquis des théories existantes et accepte in petto que le vocabulaire grammatical évolue avec la compréhension supérieure des phénomènes.
L'apprenant francophone face aux trois aspects médian, rétrospectif et perspectif de l'anglais
Authors: Coulardeau J
Published: June 2014

Cette communication examinera le problème au niveau de l'initiation à cette langue au collège. Ces trois aspects seront définis dans une perspective psychomécanique. Sera posée alors la nécessaire analyse métalinguistique à l'intérieur même de l'anglais et donc la métalangue qu'il faut viser pour que l'apprenant intègre proprement les valeurs aspectuelles de l'anglais. Cela amènera l'auteur de l'article à une approche contrastive avec la métalangue aspectuelle du français. Cet article tentera alors de montrer comment on peut articuler pour des élèves débutants les deux métalangues : types et niveaux d'explication, activités conversationnelles, activités structurales, travail sur divers types d'énoncés et de textes. Pour conclure, il sera montré que seule 1 a médiation métalinguistique peut permettre l'autonomie de réception, de production et surtout d'autocorrection. Il n'y a pas d'autocorrection sans un certain niveau de conscience métalinguistique qui dépasse 1 a simple règle. Cela d'ailleurs devrait amener à redéfinir la règle dans le cadre d'une didactique métalinguistique.
Métalangue et analyse morphologique
Authors: Kerleroux Françoise
Published: June 2014

Lorsqu'on fait un cours d'initiation à la morphologie dérivationnelle, on observe que la métalangue spontanée dont disposent les étudiants constitue un obstacle, parce qu'elle ressortit entièrement à une rationalité historique, chronologique et donc événementielle. On cherche à quoi tient ce recours spontané à l'histoire, et à quoi il sert.
Rasta resin–triphenylphosphine oxides and their use as recyclable heterogeneous reagent precursors in halogenation reactions
Authors: Xia Xuanshu , Toy Patrick H
Published: June 2014

Heterogeneous polymer-supported triphenylphosphine oxides based on the rasta resin architecture have been synthesized, and applied as reagent precursors in a wide range of halogenation reactions. The rasta resin–triphenylphosphine oxides were reacted with either oxalyl chloride or oxalyl bromide to form the corresponding halophosphonium salts, and these in turn were reacted with alcohols, aldehydes, aziridines and epoxides to form halogenated products in high yields after simple purification. The polymer-supported triphenylphosphine oxides formed as a byproduct during these reactions could be recovered and reused numerous times with no appreciable decrease in reactivity.
CHANGES IN PHYSICO-CHEMICAL PARAMETERS DURING FORCED-AERATION STATIC-PILE CO-COMPOSTING OF CATTLE MANURE WITH CALCIUM CYANAMIDE
Authors: Simujide Huasai , Aorigele Chen , Wang Chun-Jie , Yu Jun-E , Manda Bai , Lina Ma
Published: June 2014

The goal of this research was to determine the effect of CaCN2 addition into manure mixed with sawdust on the composting process under forced-aeration static condition, especially on nitrogen (N). The changes in the physical and chemical parameters over the entire composting period were evaluated. The profile of temperature, pH, and NO3 –-N was improved in the piles mixed with 2%, 3% and 4% CaCN2 (the test piles). The NH4 +-N met the limit value accepted for mature compost. Finally, the additive contents of not less than 2% but not more than 3% in CaCN2 were recommended for this system based upon a comprehensive evaluation of the measured parameters.
RATING METHODOLOGY FOR REAL ESTATE MARKETS – POLAND CASE STUDY
Authors: Renigier-Biłozor Malgorzata , Wisniewski Radoslaw , Kaklauskas Arturas , Biłozor Andrzej
Published: June 2014

The development of the real estate market is conditioned by a variety of endogenous and exogenous factors. Selected factors determine the local character of the real estate market, whereas others contribute to its classification as one of the main branches of the national economy. Rapid economic growth and the search for new investment opportunities have turned the real estate market into a highly competitive arena where various players carry out diverse investment strategies. Investors search for similarities that would enable them to develop risk minimizing strategies. Ratings are a modern tool that can be deployed in analyses and predictions of real estate market potential. This paper proposes a methodology for developing real estate market ratings, and it identifies the types of information and factors which affect decision-making on real estate markets. The following research hypotheses are formulated and tested in the article: 1) a real estate market can be rated in view of its significance for the local and national economy, 2) real estate market ratings support market participants in the decision-making process.
Privatisation des visas
Authors: Knaebel Rachel
Published: June 2014

La France et d’autres États confient à des prestataires privés une partie de la procédure des demandes de visas. De la prise de rendez-vous au recueil des données biométriques, ce n’est plus à un fonctionnaire que l’on s’adresse mais à une société privée. Un marché monopolisé par quelques entreprises. Conséquences : hausse du coût pour les demandeurs et risques pour la sécurité des données. Avec la généralisation du visa biométrique et la privatisation des procédures, la possibilité de voyager et les flux migratoires seront-ils bientôt sous le contrôle des multinationales ? Enquête * .
Marché juteux en Libye
Authors: Prestianni Sara
Published: June 2014

Des accords d’amitié et de coopération passés entre l’Italie et la Libye de Kadhafi aux accords de coopération conclus dans la période de transition qui a suivi la chute du dictateur, une entreprise sort gagnante des marchés ainsi ouverts : Finmeccanica. Gagnante encore lorsque l’Union européenne externalise le contrôle de ses frontières extérieures aux derniers pays traversés par les migrants avant de franchir la Méditerranée. Et dans ce domaine, la Libye s’est toujours montrée un collaborateur zélé... au plus grand profit de ses partenaires commerciaux.
Centres de rétention : le marché italien
Authors: Cosentino Raffaella , Saint-Saëns Isabelle , Simond Jean-Baptiste
Published: June 2014

Coopératives, sociétés créées pour l’occasion, mais aussi colosses industriels du Nord et multinationales sont en charge des centri di accoglienza per richiedenti asiles (Cara), centres d’accueil pour demandeurs d’asile), ces structures où échouent les migrants en attente d’asile. Leur gestion est devenue un pactole. Certains sont au bord de l’implosion, mais nul ne semble s’en inquiéter.
Passagers clandestins, les assureurs s'en mêlent
Authors: Maquet Paloma
Published: June 2014

Les armateurs sont juridiquement responsables des passagers embarqués clandestinement sur leur bateau. Mais du fait du risque pénal et du coût des contraventions, les mutuelles d’assurance maritimes font de la gestion des retours de ces migrants une prestation commerciale lucrative. Au mépris des droits ?
« Vous sentez que la procédure vous échappe ? »
Authors: Moyon Richard
Published: June 2014

Le 17 février 2014, comparaissaient devant le TGI de Paris les deux seules personnes à avoir été interpellées lors de l’incendie du centre de rétention de Paris (Vincennes) survenu trois jours plus tôt. Compte rendu d’une audience emblématique de la justice appliquée aux étrangers.
1996-1997 : l'épopée des Saint-Bernard
Authors: Morice Alain
Published: June 2014

Le surgissement, en 1996, sur la scène médiatique et politique d’un mouvement de sans-papiers, bientôt désigné comme celui des « Saint-Bernard », surprend presque tout le monde, associations comprises. À force de solidarité et de cohésion entre ses membres autour d’un objectif unique – la régularisation, ce mouvement va s’étendre à l’ensemble du territoire avec des conséquences inattendues.
Present Status and Future Problems on the Impact Resistance Performance Design of Civil Engineering Protective Structures
Authors: Sonoda Yoshimi
Published: June 2014

There are many civil engineering structures that have different systems and required functions. Their design methods do not have consistent design concepts. Thus, it has been pointed out the necessity of universal concepts on assumed external actions and risk for various structures and on the required level of safety. In order to meet those demands, a research committee as part of Japan Society of Civil Engineers summarizing the basic concepts of impact resistance design. This paper introduces several design methods of structures subjected to impact loads, and presents the current status and remaining issues of establishing new performance-based design methods.
Effect of Deflection Rate on Bending Deformation Behavior of Fe-Based Shape Memory Alloy
Authors: Nishikori Keizo , Iwamoto Takeshi
Published: June 2014

In this study, three-point bending test is conducted at various deformation rate by using a thin plate of Fe-based alloy. The rate sensitivity of its bending deformation during loading and shape memory effect by heating after unloading are investigated experimentally. The results obtained are summarized as bellows. (1) In the case where the quasi-static loading was applied, the positive rate sensitivity, which means the stress level increases with increasing the deflection rate, can be observed slightly. (2) It is hard to observe that recovery of deflection by SME depends on deflection rate under quasi-static loading. (3) In the case where the impact loading was applied, the positive rate sensitivity can be observed clearly.
Impact Compressive Properties of Foamed Film with Closed Cell
Authors: Yamada Hiroyuki , Okui Ryo , Ogasawara Nagahisa , Kobayashi Hidetoshi , Ogawa Kinya
Published: June 2014

The compressive properties of foamed polyethylene (PE) film with a closed cell for electronic devices have been investigated. A commercial closed cell foamed PE film with a density of 330 kg/m3 was used. Quasi-static testing was carried out at strain rates of 10−3 to 10−1 s−1. The strain rate of the impact test was approximately 105 s−1 by means of split Hopkinson pressure bar method. Within the set of experiments, the compressive stress increased with the strain rate in both the quasi-static and impact test. In particular, the flow stress increased substantially with the increasing strain rate in the impact deformation. At strains of less than 0.4, the trapped air was locally compressed within the cells, which led to the strain rate dependency of strength in the quasi-static test and the impact test.
Mechanical Behavior of Polycrystalline Aluminum under Penetration with Extremely Large Loading Rates via Molecular Dynamics Simulation
Authors: Wu Chun Yi , Wang Yun Che
Published: June 2014

In this study, polycrystalline aluminum nanoscale thin sheets are constructed by sputter deposition simulations with the molecular dynamics (MD) simulation. Subsequently, the penetration problem of a conical rigid projectile moving through the aluminum thin sheet is simulated by the MD technique. The MD simulations adopted the interatomic potential of a tight-binding type. During the deposition simulation, in order to include the ion-ion interactions, the pair-wise Moliere potential was adopted to model the interaction between working gas argon and deposited atoms. The as-deposited films did not show clear grain boundaries, but after thermal annealing, grains grow and form nanocrystalline structure with a grain size of 8 nm. The thin sheets consisted of the face-centered cubic phases of crystal unit cells, separated by grain boundaries. For the penetration simulations, four velocities were chosen 102, 103, 104 and 105 m/s. The first two velocities are called high velocity case and the rest two velocities are the hypervelocity case. Our results show that, as the penetration rate increases, more stresses are required to move the projectile through the Al film due to temperature effects from the high velocity to hypervelocity case. In addition, defects, such as dislocations, increase during the projectile penetration. In the high velocity case, the penetrated hole in the film may be recovered, but not in the hypervelocity case. The temperature difference increased in the hypervelocity case is significantly than that in the high velocity case.
Concrete Material Models in LS-DYNA for Impact Analysis of Reinforced Concrete Structures
Authors: Madurapperuma M.A.K.M. , Niwa Kazukuni
Published: June 2014

Performance of three widely used concrete material models available in LS-DYNA is compared using experimental results of drop-weight impact on a reinforced concrete (RC) beam and high speed aircraft engine missile impact on an RC wall. An overview of these material models and typical concrete material behavior shown by these models using single element analysis are also presented. The study is useful for users who have limited experience on the selection of an appropriate material model for concrete in impact simulation of RC structures.
An Analytical Study on Dynamic Strength Evaluation of Perfobond Strip Shear Connectors
Authors: Munemoto Satoru , Sonoda Yoshimi
Published: June 2014

In this paper, we conducted static push-out simulations of perfobond shear connectors (PBL) using SPH (Smoothed Particle Hydrodynamics), and validated their static strength and failure mechanism. In order to express hydrostatic pressure dependency of concrete in the analysis, The Drucker-Prager criteria with plane cap model and damage concept caused by compression fracture were applied. Appropriateness of constitutive model for concrete was confirmed on their static behaviors comparing with triaxial compression tests. Secondly, dynamic push-out test simulations were conducted using this model. The influence of input load velocity on strength and failure mechanism of perfobond shear connectors was examined.
Behaviour and Design of Steel Columns Subjected to Vehicle Impact
Authors: Al-Thairy Haitham A.B. , Wang Y.C.
Published: June 2014

The main objective of this study is to develop a simplified analytical approach to predict the critical velocity of vehicle impact on steel columns. This method utilizes the energy balance principle with a quasi-static approximation of the steel column response. Results of ABAQUS numerical simulations of the dynamic impact response of axially loaded steel columns under vehicle impact are used to validate the proposed method. To account for the effect of vehicle impact, a simplified numerical vehicle model has been adopted using a spring-mass system with a bilinear spring load-deformation relationship. The validation results show good agreement between the analytical method results and the numerical results with the analytical results tending to be on the safe side.
High-Velocity Impact between Vehicles and Soft Bodies
Authors: Yoshie Shinji , Sakai Masatsugu , Murakami Tomoaki , Fujimoto Kazuo
Published: June 2014

The speed record for a ground transportation train is held by a linear motor car, whose running speed exceeds 500 km/h. The possibility of collision with animals, generally birds, is a hazard. Thus, materials that are both lightweight and high-strength have become the ideal candidates for the front cover on bullet trains. Before studying the high-velocity impact behaviors of the candidate materials, we gathered some reference data by implementing a high-velocity impact using the aluminum alloy that was used in the testing of bird impacts on airplanes, and selected the A6061-T6 plate. The soft body was fabricated using 1.25 kg of gelatin with a collision cross section of φ100 mm; the maximum collision velocity in the tests was 550 km/h, and the target plate had dimensions of 500 × 500 × 3 mm. The plate was tested with and without a fixed peripheral part, and the results of these boundary conditions were compared. Strain gauges were attached to the backside of the plate to try to acquire the distribution of the strain history.
The test specimens were prepared from a plate from the same lot, and tensile tests at a static strain rate (10-5/s), a medium strain rate (0.1–20/s), and a high strain rate (100–1000/s) were conducted. The data for the constitutive laws of the numerical analysis were acquired and analyzed. The results of the experiment and the analysis of the strain history of the area neighboring the impact point were compared and discussed. A main conclusion of the experiment is that the target plate with a fixed peripheral part was not penetrated when the velocity was 550 km/h, and the residual displacement did not exceed approximately 60 mm. The strain energy on the dynamic characteristics to uniform elongation becomes effective in a decision for failure of a target material.
Experimental and Numerical Analysis of Repeated Impacts between Two Spheres
Authors: Minamoto Hirofumi , Seifried Robert , Eberhard Peter , Kawamura Shozo
Published: June 2014

The impact of spheres and bodies with spherical surfaces is frequently occurring in engineering applications. Only little research on repeated impacts of spheres is available and the variation of the COR (Coefficient of Restitution) due to repeated impacts is not fully understood yet. Further, the variation of the COR for impact repetition of visco-plastic materials, such as steel, has not been investigated in full detail yet. Therefore, the aim of this study is to investigate the behavior of steel spheres during repeated impact in detail in both, experiments and numerical simulations. In the experiments, two steel spheres are suspended like pendula, and the two spheres collide at the same position with the same initial velocity for every repeated impact. The COR is obtained from the velocity change of the spheres which is measured by LDVs (Laser Doppler Vibrometers) set at both sides of the spheres. The static and dynamic material properties are obtained from material tests and are incorporated into an FEM (Finite Element Method) analysis. The experimental results and the FEM results agree fairly well. It is observed that the COR increases toward to 1 by the repetition of impacts, indicating decreasing amount of plastic deformation in the successive impacts.
Modeling of Low Energy, Low Velocity Impact Failure of a Honeycomb Sandwich Material
Authors: Miron M.C. , Major Zoltan , Adachi Tadaharu
Published: June 2014

The current work is aimed at development of a numerical model able to describe complex damage phenomena that occur during an impact event in a sandwich structure having a honeycomb core. The complex material models employed within the research include linear-elastic and elasto-plastic material models having transverse isotropy as well as damage evolution models for both brittle failure and plastic failure. Within this paper remarks concerning the failure of the skins and core components as well as dissipated impact energy and affected regions are done.
Energy and Momentum Transfer to a Clamped Elastic Plate in an Air-Blast
Authors: Yuan Ye. , Tan P.J.
Published: June 2014

The momentum transfer by a planar wave impinging upon a rigid, free-standing plate in water, a largely incompressible medium, is well understood [1]. Kambouchev et al. [2] extended the results of Taylor [1] to include the nonlinear effects of compressibility whilst Hutchinson [3] has recently addressed the issues of energy and momentum transfer to a rigid, free-standing plate. In this paper, key conclusions from the aforementioned studies are critically re-examined in the context of a `fully-clamped' elastic plate. The dynamic response of an elastic plate is represented by an equivalent single-degree-of-freedom (SDOF) system. A numerical method based on a Lagrangian formulation of the Euler equations of compressible flow and conventional shock-capturing techniques, similar to that employed in [2, 3], were employed to solve numerically the interaction between the air blast wave and elastic plate. Particular emphasis is placed on elucidating the energy and momentum transfer to a `fully-clamped' elastic plate compared to its rigid, free-standing counterpart, and on whether enhancement in the beneficial effects of FSI as a result of fluid compressibility remains and to what extent.
Dynamic Axial Crushing of Empty and Foam-Filled Conical Aluminium Tubes: Experimental and Numerical Analysis
Authors: Mat Fauziah , Ismail K.A. , Ahmad Masniezam , Sazali Yaacob , Othman Inayatullah
Published: June 2014

This paper presents the crushing behaviour of empty and foam-filled conical tubes under axial dynamic loading. A nonlinear finite element (FE) model was developed and validated against experiments. The validated model was subsequently used to assess the beneficial of foam filling with regards to the variation in filler densities and tube materials. The results obtained were further analyzed and compared with straight tubes. We aim to evaluate the critical effective point for different density of fillers in foam-filled tubes based on specific energy absorption (SEA) value. The SEA value was highest for foam-filled conical aluminium tube with aluminium foam filler, followed by straight aluminium tube, straight carbon steel tube and conical carbon steel tube. Moreover, the initial peak force was found lower in aluminium tubes than carbon steel tubes and lower in conical tubes than that in straight tubes. The combination of conical aluminium tube and aluminium foam filler successfully convey the beneficial of foam filling and thus signify that proper combination and selection of tube and filler is vital in assessing the effectiveness of foam-filled tubes.
Ejecta Size Distribution Resulting from Hypervelocity Impacts between Aluminum Alloys
Authors: Nozaki Kenta , Nishida Masahiro , Hayashi Koichi , Hasegawa Sunao
Published: June 2014

We investigated the effects of impact velocity on ejecta size when aluminum alloy 2017-T4 spheres with a diameter of 3.2 mm impacted aluminum alloy 6061-T6 targets with a thickness of 30 mm at velocities of 2 to 7 km/s. We used a two-stage light-gas gun at the Institute of Space and Astronautical Science (ISAS)/Japan Aerospace Exploration Agency (JAXA). To examine the scattering angles of the ejecta, the following was placed 50 mm in front of the target: a witness plate (150 mm × 150 mm, 2 mm in thickness) made of copper with a hole of 30 mm. The ejection behaviors of fragments were observed using a high-speed video camera. The size distributions of the ejecta were examined in detail. The cumulative number of ejecta was proportional to the square of the impact velocity; in other words, to the impact energy of the projectiles. An experimental formula was created by curve fitting of the cumulative number distribution of the projected areas to a bilinear exponential distribution model when the aluminum alloy spheres struck the aluminum alloy targets.
An Investigation on the Grooved-Tapered Projectile Penetrating into the Concrete Targets
Authors: Zhang Xin Xin , Wu Hai Jun , Huang Feng Lei , Pi Ai Guo , Ma Xiu Fang
Published: June 2014

Based on the dynamic spherical cavity expansion (SCE) theory of the concrete materials and the analysis of the experimental data, both the model of the petaling penetration with low speed and the model of the round hole penetration with high speed are constructed to describe the penetration of the grooved-tapered projectile in this paper. The penetration depth and the mass abrasion are calculated using the models, so are the change of the velocity and the acceleration of the projectile with the time in the stage of the low speed penetration. The results show for the grooved-tapered projectile penetrating the concrete, the error of the penetration depth and the mass abrasion between the theoretical value calculated using the petaling penetration model and the experimental data is less than 11%, when the initial velocity is lower than about 1000m/s. When the initial velocity is higher than about 1000m/s, the error of the penetration depth between the theoretical value calculated using the round hole penetration model and the experimental data is more than 20%, and the mass abrasion calculated is almost coincide with the experimental data. The research shows the models are suitable for the analysis of the grooved-tapered projectile penetrating the concrete target, and the grooved-tapered projectile is more valuable in the high speed penetration.
Blast Resistant Design of an Embassy Building
Authors: Malhotra Ashok , Carson Dan , Stevens Tom
Published: June 2014

The paper presents a generic design study for a 2500 square meter, 4-storey embassy building. It is designed to resist blast loads from an assumed Design Basis Threat (DBT) that is provided by the owner. The building structure consists of reinforced concrete columns, beams and slabs supported on pile foundations. The exterior walls are concrete block with stone veneer. The windows are double glazed with aluminum frames. The building is situated within a compound with a perimeter wall. There is no basement.
Dynamic Deformation Behaviors of High Performance Steels
Authors: Shin Hyung Seop , Tuazon Brian , Bae Kyung Oh , Lee Sang Hyun , Yim Hyun Chang , Choi Kwang , Lee Jin Woo
Published: June 2014

The responses of three high strength steels under impact loading were examined, specifically on their strain rate dependence. Split Hopkinson pressure bar test was used in this study. Over a wide strain rate range, the Johnson-Cook model and modified Johnson-Cook mode were adopted to determine the strain rate hardening behavior of the materials. The group determined the material parameters for each metallic material tested. Obtained material parameters were used to predict the behavior of each steel at high strain rate region. The modified Johnson-Cook model was not able to represent well enough the plastic deformation behavior of steels, specifically the steel that exhibited strain softening behavior at high strain rate region.
Analysis on Low Velocity Impact Damage and Compressive Residual Strength of Composite Laminates
Authors: Xue Pu , Chen H.H. , Guo W.
Published: June 2014

This paper studies the impact damage under low velocity impact for composite laminates based on a nonlinear progressive damage model. Damage evolution is described by the framework of the continuum damage mechanics. The real impact damage status of composite laminates has been used to analyze the residual compressive strength instead of assumptions on damage area after impact. The validity of the methodologies has been demonstrated by comparing the numerical results with the experimental data available in literature. The delamination area has an error of 11.3%. The errors of residual strength and compressive displacement are 8.9% and 15%, which indicate that the numerical results matched well with the experimental data.
Finite Element Simulation of Brittle Fracture of Bulletproof Glass System
Authors: An Yong Ki , Joo Byung Yun , Chung Dong Teak , Kang Hyung
Published: June 2014

The thickness and weight of a bulletproof glass material can be reduced using strengthened glass possessing current protective abilities. In this study, numerical simulations are used to estimate the protective ability of strengthened borosilicate glass used in bulletproof glass systems. High-velocity impacts and perforation behaviors are well described by a dynamic brittle fracture model. A parametric study of the material model of glass is conducted by comparing test results of individual impacts with corresponding numerical estimations; size of back-surface spall, morphology of perforated surface, and fractured areas are compared. Material parameters of strengthened and nonstrengthened borosilicate glasses are determined. Numerical simulations using a material model with these parameters well describe the overall fracture behavior of bulletproof glass. The main parameters that affect the protective ability are initial compressive yield stress and fracture stress. Furthermore, the protective ability of strengthened borosilicate glass is ~20% better than that of nonstrengthened borosilicate glass.
Study of Material Modeling of Polymers for Impact Analysis
Authors: Takekoshi Kunio , Niwa Kazukuni
Published: June 2014

High-speed tensile tests were carried out to investigate strain rate effect on both yield stress and failure strain using ASTM D1822 Type-S specimens made of polycarbonate. Based on test results, parameters for a material model suitable for polymers are determined, and numerical analysis is carried out to simulate test results. The material model is used to simulate tensile test using a dog-bone specimen and Charpy test other than the tensile test of Type-S specimens. It is found that good predictions can be obtained when rate dependent material parameters are used. Further, the high-speed tensile test considered in the present study is suitable for selection of parameters for material modeling of polymers for impact analysis.
A Study on Reduction of Friction in Impact Compressive Test Based on the Split Hopkinson Pressure Bar Method by Using a Hollow Specimen
Authors: Kii Nobuhiko , Iwamoto Takeshi , Rusinek Alexis , Jankowiak Tomasz
Published: June 2014

The split Hopkinson pressure bar (SHPB) technique is widely-used to describe the impact compressive behavior of different materials including metals. During the impact test, the specimen deforms in a wide range of impact strain rate from 102 to 104 s-1. It is a reason why the method is studied for many years even though the structure of the apparatus based on the SHPB is simple. Actually, the cylindrical specimens are widely used for a compressive test and it is clearly seen that stress measured by the test includes the increment of stress (an error) derived by friction effect between a specimen and pressure bars. Therefore, it is important that the measured stress should indicate similar value as the proper stress of the material by reducing friction effect during not only quasi-static but also the impact test. Various attempts to reduce a friction effect in past have been conducted. A method to reduce friction effect is in general a use of lubricants. However, it is ineffective because it can be considered that this method contributes to an attenuation of the stress wave for obtaining the stress-strain curve under impact loading. Thus, rise time of waves obtained by the experiment becomes longer compared with a case not to use lubricants. Recently, a study can be found using a ring specimen, however, the determined thickness of the specimen is quite thin and it can be considered that a buckling effect cannot be vanished. In this study, a use of hollow specimen is suggested to solve the problem related to reduce the friction effect by decreasing a contact area between a specimen and pressure bars instead of a cylindrical specimen. The compressive experiments at various strain rates are conducted by using a hollow specimen.
Construction of Data Acquisition/Processing System for Precise Measurement in Split Hopkinson Pressure Bar Test
Authors: Lee Sang Hyun , Tuazon Brian , Shin Hyung Seop
Published: June 2014

The Split Hopkinson Pressure Bar (SHPB) testing technique has been used to derive the constitutive equations of engineering materials at high strain rate using the reflected and transmitted waves measured from the input and output bars. In this case, a precise measurement of the reflected and transmitted waves is important to determine a reliable stress-strain relation. In this study, to achieve the precise measurement of the reflected and transmitted waves in the SHPB experiment, a data acquisition scheme utilizing the LabVIEW software and a post processing program have been constructed. With the constructed system, an accurate data acquisition without a digital storage oscilloscope and a convenient post processing of the signals obtained through the SHPB test for identifying the mechanical properties have been possible. Therefore, a fast and simple generation of the strain rate - time curve and the nominal stress - nominal strain curve has been implemented by just selecting the specified regions on the reflected and transmitted wave profiles acquired. Also, the process to set the appropriate test configuration in the SHPB test for various kinds of materials has become easy with the constructed system.
Dynamic Tensile Response of Magnesium Nanocomposites
Authors: Chen Y. , Shim V.P.W. , Gupta Manoj
Published: June 2014

AZ31-based magnesium nanocomposites were produced by a disintegrated melt deposition technique, whereby different volume fractions of 50-nm Al2O3 nanoparticles (1.0v%, 1.4v% and 3.0v%) were used as reinforcement and added to AZ31 Mg alloy. A monolithic counterpart was also produced by the same process for comparison. Samples of these materials were subjected to dynamic tension at strain rates up to 1.2 103 s-1, using a split-Hopkinson Bar device. Compared to the quasi-static response, the monolithic and composite materials showed significantly increased yield stress and ductility under dynamic loading. The enhancement in yield stress with strain rate indicates rate sensitivity of the critical resolved shear stress for slip systems under tension. The addition of nanoparticles was found to reduce the grain size of the resulting material and increase the yield stress and ductility simultaneously, for both low and high rate loading.
Dynamic Crushing of Voronoi Honeycombs: Local Stress-Strain States
Authors: Yu Ji Lin , Liao Shen Fei , Zheng Zhi Jun , Wang Chang Feng
Published: June 2014

Dynamic stress-strain states in Voronoi honeycombs are investigated by using cell-based finite element models. Two different loading scenarios are considered: the high-constant-velocity compression and the direct impact. The 2D local engineering strain fields are calculated. According to the feature of shock front propagation, the 1D distribution of local engineering strain in the loading direction is deduced from the 2D strain fields, which provide evidences of the existence of discontinuities at shock front in cellular materials and thus enhance the basis of the continuum-based shock models. A method to quantitatively clarify the local stress-strain states ahead of and behind the shock front is developed. The results show that the dynamic stress-strain states in the densification stage obtained from both loading scenarios are different from the quasi-static stress-strain relation. The stress ahead of the shock front obtained from the high-constant-velocity compression scenario is slightly smaller than the quasi-static yield stress, but that obtained from the direct impact scenario is larger than the quasi-static yield stress. The possible mechanisms of deformation and wave propagation are explored.
Energy Absorption of Thin-Walled Beams with a Pre-Folded Origami Pattern
Authors: Ma Jia Yao , You Zhong
Published: June 2014

The bumper beam of a transport vehicle conventionally is commonly made from thin-walled materials with a shallow curved profile, with either opened or closed cross sections. Upon lateral crushing, it fails in a bending collapse mode characteristic of formation of a limited number of plastic hinges along the beam. This paper presents a novel structure known as the origami beam. It is a thin-walled shallow curved beam of square cross section whose surface is pre-folded according to an origami pattern. The origami pattern serves as a mode inducer to trigger a collapse mode that is more efficient in terms of energy absorption. Numerical simulation of the beam subjected to quasi-static lateral loading shows that a new collapse mode, referred to as the longitudinal folding mode featuring shortening of beam in the longitudinal direction prior to the formation of plastic hinges, can be triggered by the pre-folded origami pattern, leading to higher energy absorption and lower peak force than those of conventional ones. An increase in specific energy absorption (ratio between energy absorption and weight of the structure) of 23.6% being achieved in an optimum case, while the peak force is also reduced by 12.9%. Our work demonstrates that applying origami patterns to shallow curved thin-walled beams can effectively induce new collapse modes on the structures and increase the energy absorption capability.
Improvement of Energy Absorption of Circular Tubes Subjected to High Velocity Impact
Authors: Higuchi Masahiro , Suzuki Shun , Adachi Tadaharu , Tachiya Hiroshi
Published: June 2014

The dynamic behavior of circular straight and stepped tubes made of aluminum alloy under high-velocity impacts was investigated by performing finite element analyses (FEA) and an experiment. The FEA and experiment on the straight tubes suggested that while an increase in the impact velocity enhanced the absorbed energy through compressive deformation just after impact, the peak load at the fixed end was not affected by the velocity. A stepped tube that was thicker near the impacted end was designed on the basis of the results for the straight tubes, and its dynamic behavior was investigated through FEA. The stepped tube absorbed a large amount of impact energy through compressive deformation at the thicker portion during the higher-velocity impact, without increasing the maximum fixed-end load from that of the straight tube.
Numerical Evaluation of Dynamic Behavior of Axial Crushing Honeycomb Based on Adhesively-Bonded Model
Authors: Umeda Tsutomu , Mimura Koji , Kamigawa Takaaki
Published: June 2014

The axial crushing behavior of metal honeycomb was studied with laying emphasis on the effects of adhesively-bonded joint and strain rate dependence on its characteristics as an energy absorber. To introduce the influences of the plastic deformation of adhesive layer and the fracture of adhesively-bonded joint, the embedded-process-zone (EPZ) model was used. First, the axial crushing behavior of metal honeycombs (A3003 aluminum alloy and SUS430 stainless steel) was studied with changing the strain rate by low-speed and drop-weight experiments, and then the numerical model of honeycomb, which included EPZ model and the initial imperfection, was investigated by the explicit FEM code LS-DYNA. The mean buckling load calculated with EPZ model becomes smaller than that calculated with the combined model and agrees well with the experimental result. The effect of the strain rate dependence of material on the structure was also studied by the numerical simulation as well as by the experiment. A3003 honeycomb shows no strain rate dependence on the load –displacement relation while SUS430 honeycomb shows significant increase in the mean buckling load.
Dynamic Tensile Characteristics of Nuclear-Grade Graphite IG-11
Authors: Yokoyama Takashi , Nakai Kenji
Published: June 2014

The effect of strain rate up to nearly = 102/s on the tensile stress-strain properties of isotropic fine-grained nuclear-grade graphite IG-11 was investigated. Cylindrical tensile specimens machined out of graphite bars were used in both static and dynamic tests. The dynamic tensile stress-strain curves up to fracture were determined using the split Hopkinson bar (SHB). The low and intermediate strain-rate tensile stress-strain relations up to fracture were measured on an Instron 5500R testing machine. It was demonstrated that the ultimate tensile strength increases slightly, while the fracture strain and absorbed energy up to fracture decrease dramatically with increasing strain rate. Macro and microscopic examinations revealed a slight difference in the fracture surfaces between the static and dynamic tension specimens.
Damage Evaluation by Impulsive Response in Structure Filled with Liquid
Authors: Wan Tao , Naoe Takashi , Wakui Takashi , Futakawa Masatoshi , Maekawa Katsuhiro
Published: June 2014

A double-walled liquid mercury target vessel, which consists of outer and inner walls, is being globally developed for MW-class spallation neutron sources. When proton beams bombard a mercury target, pressure waves are generated due to the rapid thermal heat deposition. These pressure waves trigger impulsive vibrations in the mercury vessel, and cause cavitation damage to the inner wall of the vessel. In this study, the dependency of the vibration behavior of the mercury vessel on the damage is systematically investigated through numerical simulations and experiments, for inner wall damage characterized by hole diameters of 1, 5, 10, 20, and 40 mm. A method referred to as wavelet differential analysis is developed, and a parameter referred to as average intensity is derived for a quantitative damage evaluation. Both the numerical simulation and experimental results show that the average intensity is damage-sensitive and depends on the damage feature size. The critical damage hole diameter is estimated to be 10 mm during damage evaluation.
Visible Light Photodegradation of Azo Dye by Cu/TiO2
Authors: Riaz Nadia , Kait Chong Fai , Man Zakaria , Dutta Binay K. , Ramli Raihan M. , Khan Muhammad Saqib
Published: June 2014

Cu/TiO2 photocatalysts with different metal loading were prepared via modified depositionprecipitation method with the intention to reduce the band gap for Orange II degradation and mineralization under visible light radiation. The photocatalysts were characterized using thermal gravimetric analysis, powder X-ray diffraction, diffuse reflectance UV-Visible spectroscopy and field-emission scanning electron microscopy. 10 wt% photocatalysts showed the best performance compared to the bare TiO2.