bluuebunny/crossref_metadata_2025 huggingface dataset:
A Review of Methods for Sensing the Nitrogen Status in Plants: Advantages, Disadvantages and Recent Advances
Authors: Muñoz-Huerta Rafael , Guevara-Gonzalez Ramon , Contreras-Medina Luis , Torres-Pacheco Irineo , Prado-Olivarez Juan , Ocampo-Velazquez Rosalia
Published: August 2013

Nitrogen (N) plays a key role in the plant life cycle. It is the main plant mineral nutrient needed for chlorophyll production and other plant cell components (proteins, nucleic acids, amino acids). Crop yield is affected by plant N status. Thus, the optimization of nitrogen fertilization has become the object of intense research due to its environmental and economic impact. This article focuses on reviewing current methods and techniques used to determine plant N status. Kjeldahl digestion and Dumas combustion have been used as reference methods for N determination in plants, but they are destructive and time consuming. By using spectroradiometers, reflectometers, imagery from satellite sensors and digital cameras, optical properties have been measured to estimate N in plants, such as crop canopy reflectance, leaf transmittance, chlorophyll and polyphenol fluorescence. High correlation has been found between optical parameters and plant N status, and those techniques are not destructive. However, some drawbacks include chlorophyll saturation, atmospheric and soil interference, and the high cost of instruments. Electrical properties of plant tissue have been used to estimate quality in fruits, and water content in plants, as well as nutrient deficiency, which suggests that they have potential for use in plant N determination.
Principle Research on a Single Mass Piezoelectric Six-Degrees-of-Freedom Accelerometer
Authors: Liu Jun , Li Min , Qin Lan , Liu Jingcheng
Published: August 2013

A signal mass piezoelectric six-degrees-of-freedom (six-DOF) accelerometer is put forward in response to the need for health monitoring of the dynamic vibration characteristics of high grade digitally controlled machine tools. The operating principle of the piezoelectric six-degrees-of-freedom accelerometer is analyzed, and its structure model is constructed. The numerical simulation model (finite element model) of the six axis accelerometer is established. Piezoelectric quartz is chosen for the acceleration sensing element and conversion element, and its static sensitivity, static coupling interference and dynamic natural frequency, dynamic cross coupling are analyzed by ANSYS software. Research results show that the piezoelectric six-DOF accelerometer has advantages of simple and rational structure, correct sensing principle and mathematic model, good linearity, high rigidity, and theoretical natural frequency is more than 25 kHz, no nonlinear cross coupling and no complex decoupling work.
Tacholess Envelope Order Analysis and Its Application to Fault Detection of Rolling Element Bearings with Varying Speeds
Authors: Zhao Ming , Lin Jing , Xu Xiaoqiang , Lei Yaguo
Published: August 2013

Vibration analysis is an effective tool for the condition monitoring and fault diagnosis of rolling element bearings. Conventional diagnostic methods are based on the stationary assumption, thus they are not applicable to the diagnosis of bearings working under varying speed. This constraint limits the bearing diagnosis to the industrial application significantly. In order to extend the conventional diagnostic methods to speed variation cases, a tacholess envelope order analysis technique is proposed in this paper. In the proposed technique, a tacholess order tracking (TLOT) method is first introduced to extract the tachometer information from the vibration signal itself. On this basis, an envelope order spectrum (EOS) is utilized to recover the bearing characteristic frequencies in the order domain. By combining the advantages of TLOT and EOS, the proposed technique is capable of detecting bearing faults under varying speeds, even without the use of a tachometer. The effectiveness of the proposed method is demonstrated by both simulated signals and real vibration signals collected from locomotive roller bearings with faults on inner race, outer race and rollers, respectively. Analyzed results show that the proposed method could identify different bearing faults effectively and accurately under speed varying conditions.
“Bring It under the Legacy Umbrella”: Olympic Host Cities and the Changing Fortunes of the Sustainability Agenda
Authors: Gold John , Gold Margaret
Published: August 2013

A concern for enduring urban outcomes lies at the heart of the Olympic Games in a way that no other sporting or cultural event can match, but each age has recast the ways in which such outcomes have been framed in light of its own values and needs. Seen against that background, this paper examines the evolution of the Olympic movement’s sustainability agenda. It first considers how the environment emerged as an issue within the Winter Games through concerns over environmental protection, discusses measures introduced to embed sustainability into official Olympic practice, and explores the evolution of the dynamic relationship between sustainability and the overlapping but, to some extent, rival concept of “legacy”. The latter part of the paper illustrates these ideas with regard to the London 2012 Summer Olympic and Paralympic Games. It analyses the “One Planet Games” concept, how this was developed for the bid, and how it was subsequently put into practice, commenting particularly on the carbon footprint, creation of the Olympic Park (as sustainable legacy) and the promotion of sustainable living. The conclusion comments on the continuing challenges encountered in implementing sustainability plans and addressing long-term legacy.
Molecular Characterization and Phylogenetic Analysis of New Variants of the Porcine Epidemic Diarrhea Virus in Gansu, China in 2012
Authors: Tian Yufei , Yu Zhijun , Cheng Kaihui , Liu Yuxiu , Huang Jing , Xin Yue , Li Yuanguo , Fan Shengtao , Wang Tiecheng , Huang Geng , Feng Na , Yang Zhenguo , Yang Songtao , Gao Yuwei , Xia Xianzhu
Published: August 2013

Between January 2012 and March 2012, the infection rates of porcine epidemic diarrhea virus (PEDV) increased substantially in vaccinated swine herds in many porcine farms in Gansu Province, China. The spike (S) glycoprotein is an important determinant for PEDV biological properties. To determine the distribution profile of PEDV outbreak strains, we sequenced the full-length S gene of five samples from two farms where animals exhibited severe diarrhea and high mortality rates. Five new PEDV variants were identified, and the molecular diversity, phylogenetic relationships, and antigenicity analysis of Gansu field samples with other PEDV reference strains were investigated. A series of insertions, deletions, and mutations in the S gene was found in five PEDV variants compared with classical and vaccine strains. These mutations may provide stronger pathogenicity and antigenicity to the new PEDV variants that influenced the effectiveness of the CV777-based vaccine. Our results suggest that these new PEDV variant strains in Gansu Province might be from South Korean or South China, and the effectiveness of the CV777-based vaccine needs to be evaluated.
Viral Subversion of the Nuclear Pore Complex
Authors: Le Sage Valerie , Mouland Andrew
Published: August 2013

The nuclear pore complex (NPC) acts as a selective barrier between the nucleus and the cytoplasm and is responsible for mediating communication by regulating the transport of RNA and proteins. Numerous viral pathogens have evolved different mechanisms to hijack the NPC in order to regulate trafficking of viral proteins, genomes and even capsids into and out of the nucleus thus promoting virus replication. The present review examines the different strategies and the specific nucleoporins utilized during viral infections as a means of promoting their life cycle and inhibiting host viral defenses.
Disease Factors in Early Rheumatoid Arthritis Are Associated with Differential Risks for Cardiovascular Events and Mortality Depending on Age at Onset: A 10-year Observational Cohort Study
Authors: Ajeganova Sofia , Andersson Maria L.E. , Frostegård Johan , Hafström Ingiäld
Published: August 2013

Objective.

To investigate, within the first 2 years of diagnosis with rheumatoid arthritis (RA), associations between disease-related measures and cardiovascular disease (CVD) and mortality in patients with RA onset before and after 65 years of age.

Methods.

The study population (n = 741; 67.5% women) was derived from the Better Anti-Rheumatic Pharmaco Therapy (BARFOT) early RA cohort, recruited 1993–1999. The mean age was 55 years (SD 14.7). The outcomes were incident CVD events and all-cause mortality until 2010. Area under the curve (AUC) for disease measures at inclusion, 1 and 2 years, and decrease in measures after 1 year were calculated.

Results.

In all, 177 CVD events and 151 deaths occurred over 10 years of observation. In adjusted Cox regression analyses, seropositivity for rheumatoid factor (RF) or anticitrullinated protein antibodies (ACPA); white blood (cell) count at diagnosis; and AUC of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and visual analog scale (VAS)-pain were associated with higher CVD risk among patients with disease onset before 65 years of age. Among patients with disease onset after 65 years, larger decreases in CRP, ESR, health assessment questionnaire (HAQ), and use of methotrexate decreased CVD risk, whereas use of glucocorticoids heightened CVD risk. AUC of CRP, ESR, HAQ, and HAQ after 2 years was related to risk of death in both age groups. Seropositivity and AUC for VAS-pain in the younger group and use of glucocorticoids in the elderly were associated with poorer survival.

Conclusion.

Early treatment of RA may improve longterm outcomes. Presence of RF or ACPA associates with CVD and mortality among RA patients with disease onset before 65 years. Age stratification may improve evaluation of risk for CVD and mortality in early RA.
Comparison of Quality and Safety Education for Nurses (QSEN)–Related Student Experiences During Pediatric Clinical and Simulation Rotations
Authors: Pauly-O’Neill Susan , Prion Susan , Nguyen Helen
Published: August 2013

Nurse educators are challenged with providing meaningful clinical experiences for students. However, patient safety regulations constrain what nursing students are able to accomplish in the pediatric setting. So, what are students actually doing in their clinical rotation? This pilot observational study was undertaken to provide a snapshot of the experiences available to nursing students that develop the six Quality and Safety Education for Nurses (QSEN) competencies. Students were directly observed during pediatric clinical and pediatric simulation rotations, and their time-on-task was calculated and categorized. Three of the six QSEN competencies were observed more often than the others during both the simulation and clinical experiences. Much work needs to be done to include all QSEN-related knowledge and skills into prelicensure clinical rotations. [
J Nurs Educ.
2013;52(9):534–538.]
Early Indicators of NCLEX-RN Performance
Authors: Schooley Angela , Kuhn Jonathan Richard Dixon
Published: August 2013

Health Education Systems Incorporated (HESI
™
) test results, course grades, and National Council Licensure Examination-Registered Nurse (NCLEX-RN
®
) outcomes of students in an associate degree nursing program at a midwestern public university were investigated. Statistical analysis revealed that introductory Fundamentals HESI test scores, more than either comprehensive HESI Exit Exam scores or other specialty HESI test scores, significantly predicted NCLEX-RN outcomes in this study (
p
< 0.05), while controlling for grade point average and high school percentile rank. In addition, of the general education courses and the nursing courses in the associate nursing program examined, Pediatric Nursing, Medical–Surgical Nursing, and Maternity Nursing course grades were found most statistically significantly influential of all the HESI test scores (
p
< 0.01). [
J Nurs Educ.
2013;52(9):539–542.]
Corneal Ectasia After LASIK in a Patient With Normal Scheimpflug Evaluation but a High Ectasia Risk Score
Authors: Goncalves Fauze Abdulmassih , Goncalves José Marcos Santos
Published: August 2013

PURPOSE:

To present a case of ectasia after LASIK that developed in a patient with normal Scheimpflug imaging but a high Ectasia Risk Score System (ERSS) score.

METHODS:

Case report.

RESULTS:

A 24-year-old woman with no preoperative abnormalities on Scheimpflug evaluation but a cumulative ERSS risk of 4 (high risk) in the right eye and 3 (medium risk) in the left eye developed ectasia in both eyes 27 months after LASIK. She underwent ultraviolet-A corneal collagen cross-linking, with no signs of further progression.

CONCLUSIONS:

In this case, the ERSS was effective at predicting ectasia risk despite normal Scheimpflug imaging and only mild asymmetry on Placido topography.

[
J Refract Surg.
2013;29(11):792–795.]
À propos de la représentation de la langue dans le cadre du CLES. Interaction verbale, interaction sociale ?
Authors: Rouveyrol Laurent
Published: August 2013

Alors que le paysage institutionnel d’apprentissage évolue à grand pas en imposant la certification en langue comme un pré-requis professionnel, il convient de s’interroger sur la représentation langagière induite en amont. Cet article se propose de revenir sur le CLES et de s’interroger sur ses fondements linguistiques au regard de l’interaction verbale notamment. En proposant une perspective actionnelle telle que le Cadre Européen Commun de Référence pour les Langues (CECRL) la définit et en imposant une interaction en fin de chaîne, le CLES offre la possibilité d’envisager l’apprenant comme un véritable acteur social en interaction avec le monde qui constitue son environnement socioculturel.
Préparation à la certification en français dans le contexte universitaire tunisien. Quels dispositifs spécifiques pour les étudiants en mastère ?
Authors: Msalmi Mohamed
Published: August 2013

Partant de la dynamique qui caractérise actuellement l’enseignement-apprentissage des langues étrangères dans le contexte tunisien, l’objectif de cet article est de présenter un projet d’implantation de la certification en langue française en milieu universitaire après l’adoption du système LMD.La présentation est suivie du compte rendu d’une expérimentation didactique que nous avons réalisée à la Faculté des sciences économiques et de gestion de Sfax (FSEGS) autour de l’élément constitutif d’une unité d’enseignement, intitulé « français : préparation à la certification » et intégré aux programmes de deux mastères en informatique appliquée.Les données ont été recueillies grâce à une double enquête menée auprès des étudiants des deux mastères (recherche et professionnel) et de leurs enseignants de français de spécialité, au cours du premier semestre de l’année universitaire 2010-2011.
Enhancing L2 learners’ noticing skills through self-confrontation with their own oral production performance
Authors: Guichon Nicolas , Cohen Cathy
Published: August 2013

The central issue of the pilot study on which this article is based concerns the potential role of metacognition in the development of second language (L2) competence, specifically when L2 learners are confronted with their own videoed oral performance. An experiment was carried out at a French university with a group of first-year non-specialist undergraduate learners of English (N=12). The collected data for this research are comprised of (1) the filmed performance of learners carrying out an oral task in English, and (2) the filmed interview in French of the same participants engaged in metacognitive reflection upon samples of their own performance. The study thus endeavours to determine the potential of self-confrontation, represented here by retrospective interviews of learners based on their own video-recorded language performance, as a way to develop noticing skills in L2.
L’approche projet et la recherche en langues : quels enjeux ?
Authors: Bertin Jean-Claude
Published: August 2013

Les modes de financement de la recherche s’appuient de plus en plus fortement sur ce que l’on a coutume d’appeler ‘l’approche projet’. L’auteur se propose d’en repérer les caractéristiques principales afin d’analyser la philosophie (l’idéologie ?) sous-jacente, en la comparant aux habitudes en la matière de la communauté des chercheurs en Sciences Humaines et Sociales (SHS). Après avoir pointé l’influence des sciences et techniques, en particulier, sur les représentations des financeurs, il commente la manière dont cette approche questionne nos disciplines et propose quelques pistes de réflexion pour une meilleure appropriation de cet outil imposé par la communauté des linguistes.
L’apprentissage informel en ligne : nouvelle donne pour l’enseignement-apprentissage de l’anglais
Authors: Sockett Geoffrey , Kusyk Meryl
Published: August 2013

L’accès à Internet permet à de plus en plus d’apprenants d’anglais, dans les pays où les émissions de télévision d’origine anglophone sont généralement doublées, de télécharger du contenu en version originale. Ces apprenants participent aussi à d’autres activités en ligne en anglais qui commencent à avoir un impact sur leurs compétences langagières. Cet apprentissage informel de l’anglais en ligne a fait l’objet de plusieurs études récentes, et le but de cet article est de présenter une synthèse des travaux que nous avons réalisés dans ce domaine depuis quatre ans. Nous aborderons des aspects qualitatifs et quantitatifs de ces phénomènes, afin d’en décrire l’ampleur et d’en mesurer l’impact sur la compréhension orale et l’expression écrite. Nous laisserons une large place à des suggestions pratiques pour la salle de classe et à des orientations futures pour ces recherches.
L’éthique : au croisement de la relation thérapeutique et éducative
Authors: Assier Marie-Lise
Published: August 2013

L’éthique est au fondement même des relations thérapeutique et éducative. Or, s’il existe des codes de déontologie définissant les droits et les devoirs des professionnels, l’éthique reste avant tout un processus personnel qui dépasse le verbalisable. Nous démontrerons que l’éthique en anglais médical est déterminante dans les rapports langue/culture/santé et ce, plus particulièrement dans la pratique clinique impliquant la relation patient/thérapeute. Donner une place à l’éthique en anglais de spécialité est un moyen de décloisonner l’enseignement médical, de mettre l’accent sur des qualités de savoir-être indispensables. La mise en perspective d’autres façons de soigner dans des traditions culturelles différentes peut aider le futur praticien à analyser la dynamique d’autres approches thérapeutiques et à comprendre les enjeux éthiques de ses actes. Dans les croisements des domaines santé/éducation, l’éthique peut permettre la convergence de moyens et d’objectifs pour une recherche pluridisciplinaire sur le développement de soi dans la relation à l’autre.
L’éthique professionnelle peut-elle se penser au singulier ? Le cas des formations dans le secteur de l’aide à la personne dépendante
Authors: Demont Guillaume
Published: August 2013

Nos travaux de recherche portent sur la pluralité des postures et logiques professionnelles à l’œuvre dans les métiers, ce que nous appelons des « moments professionnels ». Cet article montre comment ces moments professionnels s’articulent les uns aux autres dans la pratique, à travers l’exemple d’une activité professionnelle dans le secteur de l’aide à la personne dépendante. À partir de la définition que Paul Ricœur donne de l’éthique, nous observons que cette pluralité de postures et logiques professionnelles conduit à une pluralité des éthiques professionnelles en présence.À partir de là, comment penser la place de l’éthique dans une formation de français à visée professionnelle ? Comment l’éthique peut-elle devenir une composante à part entière de la langue-culture professionnelle, lorsqu’elle est enseignée à partir de récits personnels ? Comment enseigner une éthique du soignant en même temps qu’une éthique de l’éducateur ?
Les rues fermées : du collectif à la collectivité. Regards croisés Nantes/Recife
Authors: Vuaillat Fanny
Published: August 2013

Cet article propose une analyse des rues fermées, publiques ou privées, dans deux contextes différents, Nantes en France et Recife au Brésil. Ce double regard analytique permet de s’extraire des effets de contextes pour tenter de percevoir le sens commun de ces rues dans la fabrique de la ville fermée. À partir d’une série d’observations et d’entretiens auprès de responsables techniques ou politiques des pouvoirs publics locaux, ainsi qu’auprès d’habitants, plusieurs rues fermées servent à appréhender la manière dont l’installation d’un obstacle au passage instaure une frontière qui impose un rapport négocié, non exempt de frictions, du collectif à constituer à la collectivité. Cette limite ne sert pas tant un entre-soi affinitaire, qu’elle ne préserve des intérêts communs, pour lesquels il s’agit de former un collectif. Il faut donc trouver un équilibre, qui s’avère être soit frictionnel, soit établi sur la base d’un consensus a minima. Mais les pouvoirs publics, avec un discours ambigu, laissent des marges de manœuvre à une négociation en initiant une gouvernance urbaine sur les bases de frontières, physiques et juridiques, malléables et poreuses.
Les condominios brésiliens : des territoires politiques sans peuple
Authors: Guirriec Patrick Le
Published: August 2013

L’évolution des sociétés contemporaines et la mondialisation ont pour effet l’homogénéisation culturelle et la dilution des groupes d’appartenance. En réaction à ces phénomènes se multiplient diverses formes de repli communautaire (ethnique, religieux, résidentiel...) où les individus sont à la recherche de nouvelles identités. S’il apparaît que les formes de ségrégation sociospatiales, les regroupements résidentiels entre pairs, répondent à cette volonté de repli, à un besoin de revendication identitaire, on pourrait alors imaginer que ces espaces urbains homogènes constituent des processus de communalisation, au sens wébérien du terme, et des formes de territorialisation des rapports sociaux à une époque où l’on évoque plutôt les phénomènes de déterritorialisation. Les condominios semblent répondre, au moins partiellement, à cette logique de repli et il est intéressant d’étudier les relations qui se nouent, tant à l’intérieur des murs, que dans les rapports avec la société globale, en se demandant notamment s’il s’agit de territoires politiques, et par conséquent de formes de sécession par rapport à l’État.
Fermeture résidentielle et politiques urbaines, le cas marseillais
Authors: Dorier Elisabeth , Berry-Chikhaoui Isabelle , Bridier Sébastien
Published: August 2013

La fermeture résidentielle à Marseille se caractérise par son intensité (presque 20 % du total des logements de la commune) et son emprise spatiale très forte dans certains quartiers (plus de 40 % de leur surface urbanisée). Issu d’une recherche de 3 ans et d’un rapport de recherche remis au PUCA en 2010 (« La diffusion des ensembles résidentiels fermés à Marseille. Les urbanités d’une ville fragmentée »), l’article propose d’enrichir la lecture des processus complexes du cloisonnement résidentiel en s’attachant, d’une part, aux effets de contextes géohistoriques, particulièrement aux héritages fonciers (temps long de la production des espaces urbains) et, d’autre part, aux synergies actuelles entre une action municipale orientée vers l’attractivité territoriale et une offre immobilière spéculative. La multiplication des partenariats publics-privés semble ici dissoudre le fameux dualisme identifié par Mangin (2004) entre « urbanisme de produit » et « urbanisme de projet ».
Les ensembles d’habitat individuel fermés en Ile-de-France. Des morphologies surprenantes, à l’encontre des images supposées
Authors: Loudier-Malgouyres Céline
Published: August 2013

Face aux inquiétudes ambiantes sur la montée de la fermeture résidentielle, l’étude présentée ici a cherché à mesurer la production récente des ensembles d’habitat individuel fermés en Ile-de-France. Les résultats sont surprenants ; ils montrent un phénomène tout à fait mineur sur le plan quantitatif et des formes plutôt bien intégrées à leur environnement urbain, participant même à l’effort actuel de densification urbaine. Face à ces ensembles fermés, et au-delà des inquiétudes liées aux valeurs de ces figures, quelles sont les questions qui se posent aux collectivités locales en termes d’aménagement et de gestion de leur territoire ? Sans réellement contribuer au modèle redouté de ville fermée et sécurisée, ces formes urbaines, rigides et faiblement mutables, tendent en effet à figer le tissu urbain et à peser d’un poids non négligeable dans la gestion communale.
Cooperation in Crisis? An Analysis of Cross-Border Intermunicipal Relations in the Detroit-Windsor Region
Authors: Nelles Jen
Published: August 2013

The Detroit-Windsor region is linked by the automotive industry, significant cross-border labor and recreation flows, cultural similarities, and social problems stemming from the economic downturn. According to theories of cross-border cooperation this case should be one characterized by a degree of institutional integration and intermunicipal coordination. In reality, very few cross-border political relationships exist between local authorities in the region, even in this time of mutual crisis. This paper investigates the reasons for weak cross-border integration by testing theory against practice and argues that existing theoretical frameworks do not satisfactorily account for observed patterns of cooperation in the region. It also explores the different effects that crisis can have on cross-border partnerships at the metropolitan scale.
Implementing transparency in an Eastern European office market: preparing Warsaw for global investments
Authors: Bitterer Nadine , Heeg Susanne
Published: August 2013

In the aftermath of an increasing integration of property and financial markets, the real estate industry is subject to soaring internationalization processes. Since international institutional investors appeared, transnational real estate investments have increased tremendously. In recent years, Central and Eastern European countries have been becoming more attractive to institutional investors and are therefore being integrated into international market structures. Within these countries, Warsaw emerged as the most dynamic and important real estate market. But what are the mechanisms and practices through which the real estate market of Warsaw becomes international? Which networks, intermediaries and frames are necessary to constitute a mature real estate market? The article argues that international real estate consultants are playing a crucial role in the underlying internationalization process. They are acting at the interface between investors, developers, construction companies and tenants and are therefore becoming a crucial hinge between real estate actors. With the example of the Warsaw real estate market we argue that international real estate consultancies are key drivers of the transformation process from a local to a global market. They transfer global knowledge, competence and practices and implement transparent and professional structures in the emerging Warsaw real estate market.
Seismic Time-History Analysis of Gravity Dam Based on Nonlinear Finite Element Method
Authors: Zhu He , Wang Gang , Ma Zhen Yue , Su Yi Kang
Published: August 2013

A cohesive model (CM) was introduced in this paper. The constitutive response of cohesive behavior depends on a traction-separation description characterized by the initial stiffness, damage initiation threshold, and damage evolution properties.Through the aseismic analysis of a gravity dam, the displacement, stress and anti-sliding safety factor were discussed in the paper, the results were also compared between elastic model (EM) and plastic model (PM). The results shown that the displacement amplitude computed by PM and CM was nearly twice larger than that by EM, and the area of stress concentration became not so obvious. The cohesive model could efficiently simulate the discontinuous structure and the responses of seismic computed by PM and CM were more correspond to actual situation.
A New Designed Hot Tearing Apparatus Based on the Applied Forces
Authors: Xu Rong Fu , Zheng Hong Liang , Zhang Yong , Ding Su Pei , Zhang San Ping , Tian Xue Lei
Published: August 2013

The objective of this paper is to introduce a simple experimental apparatus based on the applied forces for quantitative assessment on hot tearing behavior in aluminum alloys. According to the experimental procedure, molten metal is cast in the rod-shaped mold cavity. One side of the casting specimen is hooked by a steel bolt which restrains its free contraction and transfers the tensile forces during solidification. A steel threaded rod connected to a load cell which records the real-time measurement of the tensile forces during every experiment. Thermal history is monitored by K-type thermocouple. The data of the temperature and tensile forces are acquired by a data acquisition system. Test of the experimental apparatus is conducted with A356 and Al-5wt%Cu alloy to investigate the accuracy of the experimental apparatus and modify its operating parameter. The tensile forces curves and the temperature curves of the specimens are obtained by experiment. This data provide useful information about hot tearing formation and solidification characteristics, from which their quantitative relations are derived. In this manner, the hot tearing behavior in aluminum alloys can be studied by this experimental apparatus based on the applied forces.
Effect of Temperature on Electrochemical Behavior of Stainless Steel in Phosphoric Acid
Authors: Shi Wen , Xiang Song , Li Yan Li , Yang Ming , Hu Ya Nan , Wang Quan Ding
Published: August 2013

Electrochemical behavior of 304L and S32304 stainless steel in different temperature and concentration phosphoric acid solution by means of polarization curve and electrochemical impedance spectroscopy. The results showed that with the increase of the phosphoric acid solution temperature, the corrosion voltage and the corrosion current of the stainless steel increase and the polarization resistance and solution resistance decrease. The corrosion-resistant properties of S32304 stainless steel are superior to that of 304L stainless steel.
Application and Improvement of PSO Algorithm in Structural Damage Diagnosis
Authors: Guo Hui Yong , Wu Qin Bin , Li Zheng Liang
Published: August 2013

In order to study Particle Swarm Optimization (PSO) algorithm and structural damage diagnosis, a method based on PSO algorithm and Evidence theory is presented in this paper. First, structural frequency and modal strain energy are considered as two kinds of information sources, and frequency change method and modal strain energy method are utilized to extract damage information. Then, evidence theory is utilized to integrate the two information sources and preliminarily detect structural damage locations. Finally, the PSO algorithm is used to identify structural damage extent. An improved PSO algorithm is also presented. Simulation results show that the evidence theory can identify the suspected damage locations, and the PSO algorithm can precisely detect the damage extent. It can also be observed that the improved PSO algorithm is obviously better than the simple PSO algorithm.
Analysis of Effective Pre-Stress and Stiffness of the Continuous Rigid Frame Bridge in Service Based on Inversion Theory
Authors: Zhang Zhao Ning
Published: August 2013

Due to the shrinkage, creep, friction and other factors, the pre-stress applied to the beam is not a constant. It is important to obtain the information of the pre-stress in order to ensure security of the bridge in service. To solve the problem mentioned above, the paper puts forward a new way to analyze the effective pre-stress using the displacement inversion method based on the inversion theory according to the measured vertical deflection of the bridge in service at different time. The method is a feasible way to predict the effective pre-stress of the bridge in service. Lastly, taking the pre-stressed concrete continuous rigid frame bridge for example, the effective pre-stress and stiffness are analyzed by establishing the finite element model.
Vibration Control of Offshore Platform Based on Outrigger Damping System
Authors: Sun Yu Hong , Niu Qun , Nie Li Wu , Zhang Ji Gang
Published: August 2013

Outrigger damping system is used in JZ20-2 north high wellhead platform, making simulation analysis to the whole structure subjected to pushing ice load by finite element software ANSYS, calculating displacement and acceleration response under different length of horizontal pole and different height of damper. The height of the damper has great influence on displacement and acceleration. The damping effect of horizontal bar length has an impact on the damping system, and the main influencing factor is the damper height, and when the height is H2 the damping effect is the most ideal.
FBG Earth Pressure Sensors Applied in Surrounding Rock Pressure of Tunnel
Authors: Cai Zhou Chun , Li Chuan , Guan Yuan Yu , Chen Wu Fen , Guo Li Jun , Chen Fu Yun , Zhao Zhen Gang , Xie Tao
Published: August 2013

During the period of tunnel excavation, shoring, forming and long-term operation, stress changes of tunnel surrounding rock are complex, the real-time monitoring of surrounding rock pressure is the key factor in ensuring long-term stability in tunnel. Fiber Bragg grating earth pressure sensors apply in surrounding rock pressure of tunnel which can change the pressure of the surrounding rock into fiber Bragg grating wavelength shift. According to the feature of pressure and temperature in Tian Xin Tunnel, 40 earth pressure sensors are embedded in 20 representative sections and one earth pressure sensor is embedded in each arch shoulder. In addition, one temperature compensation sensor is embedded in each arch crown. During the 235 monitoring days, the biggest daily change of surrounding rock pressure reaches 800 KPa. In 3 months of the sensor installation, the average monthly variation is within 50 KPa. The long-term measurement results indicate that the changes of surrounding rock pressure are different in different locations. When the surrounding rock is close to the excavated and blasted surface the surrounding rock pressure changes largely.
Experimental Research on Embankment Hidden Defects Monitoring Using Distributed Optical Fiber Sensor
Authors: Zhou Yang , Zhu Ping Yu , Li Shu Yu
Published: August 2013

Distributed optical fiber sensor for temperature and strain identification as the basis, the optical fiber sensor has advantages to monitor deformation and seepage in the embankment dam relying on its long distance and continuous monitoring ability. Taking layout of layered installation, the relationship between laying bending radius and the strain of the optical fiber sensor is studied. Indoor simulation test and local outdoor dam model test show that, the distributed optical fiber sensor for dam defect monitoring has good effect and application prospect. The embankment dam model provides experimental platform to further study early warning criterion of impending disaster in embankment dam.
Numerical Simulation of Bolt Looseness Monitoring Based on Impedance Method
Authors: Sun Wei , Zhang Ying
Published: August 2013

A monitoring method based on impedance method was researched for bolt looseness of steel structure. First, the basic principle of impedance method and its characters were introduced. Then, the root mean square of admittance (reciprocal of impedance) real part was used as the index to identify the damage degree. At last, a numerical simulation research on the monitoring of bolt loosen based on impedance method was hold by finite element analysis software. In research, a model of bolted connection joint of steel structure was built according to subsistent test by finite element method (FEM) software, and different levels of bolt loosen were simulated. The researched results had shown that the impedance method is efficient for the monitoring of bolt loosen. And the damage index could reflect damage tendency well. The simulation results are good agreement with test.
Arch Dam Deformation Prediction Model Based on PSO-SVM
Authors: Liu Jing Yang , Liu He Zhi
Published: August 2013

Arch dam has gradually evolved as one of dam type as main large-scale hydraulic project, dam deformation prediction is an important part of dam safety monitoring, and it is difficult to forecast because of the complicated nonlinear characteristics of the monitoring data. Support Vector Machine (SVM) could solve the small sample, nonlinear high dimension problem due to the excellent generalization ability, and hence it has been widely used in the forecast of arch dam deformation. However, the forecast results considerably depend on the choice of SVM model parameters. In this paper, Particle Swarm Optimization (PSO), which has the characteristic of fast global optimization, was applied to optimize the parameters in SVM, and then the dam deformation prediction model based on PSO-SVM could be established. The model is applied to a certain arch dam foundation prediction. The accuracy of this employed approach was examined by comparing it with multiple regression method. In a word, the experimental results indicate that the proposed method based on PSO-SVM can be used in arch dam deformation prediction.
Research on Cable Force Testing Method of Cable-Stayed Bridge Model Test
Authors: Li Yan Qiang , Du Yan Liang
Published: August 2013

A new method of measurement of the cable force in cable-stayed bridge model test is introduced. Pressure ring sensor is used as the main component in this method and the tension of the stay cables can be measured real-time and in time. It is vertified that this method is exact and credible by model test and can be used in actual cable-stayed bridge. The static measurements for the test model are conducted. The testing results are compared with the numerical results of finite element model developed for the test model. A platform is established for the future researchs.
A Study on the Quality Assessment System of External Prestressing Reinforcement Technology
Authors: Xu Ji Li , Yi Zi Lin , Yang Jing Jing
Published: August 2013

For external prestressing reinforcement technology, corresponding quality assessment system is established based on analytic hierarchy process (AHP). At the same time, the actual application process of the system was found. Structure of judgment matrix, synthetic weight and for each layer of element and fuzzy comprehensive evaluation was figured out. Finally, the system is verified by practical engineering. Something is obvious as the result shows. Firstly, the comprehensive assessment system for reinforcement quality of bridges is reasonable and practical. Secondly, this system takes some advantages to the systematization, standardization and theorization for the assessment to reinforcement quality of bridges.
Collapse of the Historic City Walls of Pistoia (Italy): Causes and Possible Interventions
Authors: Andreini Marco , de Falco Anna , Giresini Linda , Sassu Mauro
Published: August 2013

In the paper are discussed the likely causes of the collapse and the temporary safety features adopted to secure a collapsed portion of the Historic Walls of the city of Pistoia (Italy). The walls of medieval origin, affected by various subsequent modifications and alterations, have been subjected to a sudden collapse, after a period of heavy rain, for a length of about 25 meters. Hereby are described the probable causes of the collapse, due to a poor quality of the walls (external façades with external layer made up of river pebbles and inner filling material in-coherent), height of building is not modest (approximately eleven meters), a significant differential in height between the two faces (about four meters) and a not unlikely rotation of the base. It is proposed a technique of temporary reinforcement with a system of steel tie-beams and braces with a view to the work of reconstruction of the partially collapsed and consolidation of the lateral parts of wall.
Behavior of Pre-Cracked Reinforced Concrete Beam Strengthened with Prestressed CFRP Plate
Authors: Wang Bo , Peng Hui , Zhang Jian Ren
Published: August 2013

The technique of strengthening structures with prestressing CFRP can improve the load-carrying behavior of reinforced concrete structures and has gained more and more attention recent years. However the research about behavior of the pre-cracked structures after retrofit is rather limited. In this paper two RC beams with large dimension were constructed. One beam was strengthened by non-prestressed CFRP plate serving as reference beam. And the other beam had been loaded to its yielding load before it was strengthened with a prestressed CFRP plate. The monotonic tests were conducted to investigate the effect of strengthening with prestressed CFRP on the behavior of the pre-damaged beam. Based on the experiment results, the comparison of behavior between the beam with non-prestressed CFRP plate and the pre-cracked beam with prestressed CFRP was conducted. The experiment results indicated that although having been loaded to its steel yielding before being strengthened, the specimen with prestressed CFRP plate had a load-carrying capacity no less than the intact beam with non-prestressed CFRP plate. Despite the serious damages of section, the stiffness of the pre-cracked specimen was almost equal to that of the reference specimen, which indicates that the technique of strengthening structures with prestressed CFRP plates can be effective in the retrofit of the seriously cracked reinforced concrete structures.
A Discussion about Construction Techniques to Improve Durability of Concrete Bridges in Alpine Regions
Authors: Rui Jie , Li Guo Ming , Wang Bing , Wang Zong Ren
Published: August 2013

Based on the discussion of the quality control and management requirements for the concrete raw materials, the raw materials preservation heat in the mixing concrete process and the note in the process of transportation with the requirements both in concrete casting process and the casting vibrating process, the paper proposes the construction key technology of improving the durability of the concrete in alpine region.
Seismic Performance of RC Short Columns Strengthened with BFRP
Authors: Ding Bin , Ouyang Li Jun , Lu Zhou Dao , Chen Wei Zhen
Published: August 2013

BFRP has excellent strength, durability, thermal properties and economic cost. To test seismic performance of short columns strengthened with BFRP. Low cyclic loading test was conducted on one comparative short column and two RC short columns strengthened with BFRP. The test shows that short columns warped by BFRP show excellent failure modes, shear capacity, ductility and energy dissipation. As a new fiber reinforced plastic, BFRP has a good prospect in the area of seismic strengthening for its low cost and comprehensive mechanical properties.
Research on the Mechanism of Prestressed Loss for Curving Hole of Prestressed Concrete Structure Caused by Frictional Resistance
Authors: Zhang Shan , Zhang Kai Yin , Xie Bing Yang , Fan Zhong Lin
Published: August 2013

Excessive prestress loss in Prestressed Concrete (PC for short) continuous beam bridges and continuous rigid frame bridges cause structures to be different types of diseases. Based on theoretical analysis and experiment , this paper points out the imperfection of the effective prestress formula in Curving Hole at present. According to the research on the influencing factor of prestressed loss in Curving Hole of friction coefficient, it plays a remarkable role on the analysis about the prestressed loss in Curving Hole of prestressed concrete structure.
Research of Non-Probabilistic Reliability of Soil Structure of High-Grade Highway Based on Interval Analysis
Authors: Mu Huan Sheng , Gao Ling
Published: August 2013

In this paper, through the study on the non-probabilistic based on the interval analysis of soil structure, solves the key theoretical issues of non-probability measure and methods, It is more suitable for evaluation of the roadbed design problems with less experimental data.
Influence of Water Content on Dynamic Elastic Modulus of Concrete
Authors: Zhu Fang Zhi , Zhao Tie Jun , Guan Ting
Published: August 2013

Water content is one of key effect factors on the dynamic elastic modulus, which is an important damage assessment index of concrete structures induced by freeze-thaw cycles, fire and chemical attacks. Through the ultrasonic and bending vibration test, the regularity of dynamic elastic modulus changed with the water content of concrete specimens was analyzed in this paper. The results show that the ultrasonic velocity has a low sensitivity to water content when it is below 1.5%. The bending vibration method can better reflect the effect of water content change on dynamic elastic modulus. The regression equation of dynamic elastic modulus and water content was set up by introducing the index function. The research results offer technical reference for the predicting of actual concrete dynamic elastic modulus in different humidity environment.
Current Situation of Researches on Durability of R.C. Structures
Authors: Li Zhong Yuan
Published: August 2013

The durability of R.C. structure as a significant indication is widely considered in structure design where the environmental influence research is the basis of study on durability of R.C. structures. The main factors which cause the structure durability degradation are the abbreviation of concrete interface, the concrete quality deterioration and the corrosion of the reinforcing bar. On the basement of comprehensive studies of the current researches on structure durability, the article offers overall reviews and perspective comments on the current durability researches from the aspects of environmental influences, durability analysis methods and structural degradation factors to propose valuable measures for further studies.
Structural Reliability Analysis with Multi-Failure Models Using High-Dimensional Model Representation
Authors: Zhao Wei Tao , Jia Lei , Niu Cheng Kui
Published: August 2013

Based on the high dimensional model representation (HDMR) and Monte Carlo simulation (MCS), this paper presents the improved method used to evaluate the failure probability of the system with multi-failure models. The HDMR is a general set of quantitative model assessment and analysis tools for capturing the high-dimensional relationships between sets of input and output model variables. Once the limit state function is defined by using the HDMR, the failure probability can be obtained by using the MCS without increasing computational efforts. The series and parallel system are considered in this paper, a numerical example is presented to demonstrate the efficiency and the accuracy of the proposed method. It is shown that the efficiency of the HDMR are both high in terms of series system and parallel system, the accuracy can be acceptable with respect to series system, and the accuracy can not be acceptable with respect to parallel system.
Probability Function Estimation of Rock Random Variables Using Chebyshev Orthogonal Polynomial
Authors: Gong Feng Qiang , Hou Shang Qian , Wu Ting Yu
Published: August 2013

The Chebyshev orthogonal polynomial with sample moments (the origin moments) were used to approximate the probability density function (PDF) or cumulative distribution function (CDF) of variable (CPA method). Three examples from observed datas of uniaxial compressive strength of a kind of hard rock were presented for illustrative purposes. The results show the PDF or CDF of rock variables can be accurately derived from CPA method with sample moments. The relative errors of estimation by CPA method is much smaller than that of TDF method (PDF fitted by some standard theoretical distributions). It is suggested that the presented method can be used in stochastic reliability analysis of rock engineering.