bluuebunny/crossref_metadata_2025 huggingface dataset:
Geographic variation in resistance to nectar robbing and consequences for pollination
Authors: Adler Lynn S. , Leege Lissa M. , Irwin Rebecca E.
Published: October 2016

PREMISE OF THE STUDY:

Floral evolution is frequently ascribed to selection by pollinators, but may also be shaped by antagonists. However, remarkably few studies have examined geographic mosaics in resistance to floral antagonists or the consequences for other floral interactions.

METHODS:

Gelsemium sempervirensexperiences frequent nectar robbing in northern Georgia, but rarely in southern Georgia. We conducted common‐garden experiments in both locations using genotypes from each region and measured robbing, pollinator attraction, floral attractive and defensive traits, and plant reproduction.

KEY RESULTS:

Nectar robbing was more than four times higher in the north vs. south, and pollinator visits did not differ between gardens. Across both gardens, northern genotypes were half as likely to be nectar‐robbed but received half as many pollinator visits as southern genotypes, suggesting evolution of resistance to robbing at a cost of reduced pollinator attraction. Plant‐level traits, such as height and number of flowers, were more closely associated with resistance to robbing than floral size, shape, or chemistry. Northern genotypes had lower female and estimated male reproduction compared to southern genotypes at both locations, which could be due to costs of resistance to nectar robbing, or costs of adaptations to other biotic or abiotic differences between regions.

CONCLUSIONS:

Our study indicates that geographic variation can play a strong role structuring interactions with floral antagonists and mutualists and provides evidence consistent with the hypothesis that local resistance to nectar robbing imposes costs in terms of decreased pollinator attraction and reproduction.
Prezygotic resource‐allocation dynamics and reproductive trade‐offs in Calymperaceae (Bryophyta)
Authors: Pereira Marta R. , Dambros Cristian S. , Zartman Charles E.
Published: October 2016

PREMISE OF THE STUDY:

Resource allocation is difficult to characterize in plants because of the challenges of quantifying gametes and propagules. We surveyed six sympatric, unisexual species in the family Calymperaceae (Bryophyta) to test for trade‐offs in prezygotic sexual and asexual expression and density‐dependent survivorship of female gametangia.

METHODS:

We tallied gametangial and asexual propagule output for 1820 shoots from 17 populations of six species at monthly intervals during one year (2010–2011) in a central Amazonian forest. Generalized linear mixed models were used to test for trade‐offs in sexual and asexual expression and density‐dependent senescence probability of gametangia. Precipitation and microsite variables were also included in the model.

KEY RESULTS:

For all species, sexual and asexual expression were positively correlated with mean monthly precipitation. Asexually expressing shoots produced significantly fewer gametangia than nonexpressing ones, and the probability of senescence increased with shoot density. Archegonium density per shoot was also consistently lower than the modeled optimum to maximize the number of receptive archegonia.

CONCLUSIONS:

Trade‐offs among reproductive strategies and positive density‐dependent senescence of female gametangia suggest that prezygotic sexual and asexual expression come at a tangible investment. However, the apparently inefficient resource‐allocation dynamics in the production of female gametangia makes the possible advantages of squandering such investments unclear. One possibility is that the study populations, like those of many dioicous mosses, are skewed toward expressing females with low sporophyte production, which would suggest that asexual reproduction predominates and upstages efficient resource allocation in prezygotic investment.
A composite structure based on reduced graphene oxide and metal oxide nanomaterials for chemical sensors
Authors: Galstyan Vardan , Comini Elisabetta , Kholmanov Iskandar , Ponzoni Andrea , Sberveglieri Veronica , Poli Nicola , Faglia Guido , Sberveglieri Giorgio
Published: October 2016

A hybrid nanostructure based on reduced graphene oxide and ZnO has been obtained for the detection of volatile organic compounds. The sensing properties of the hybrid structure have been studied for different concentrations of ethanol and acetone. The response of the hybrid material is significantly higher compared to pristine ZnO nanostructures. The obtained results have shown that the nanohybrid is a promising structure for the monitoring of environmental pollutants and for the application of breath tests in assessment of exposure to volatile organic compounds.
X-RAY FLASHES IN RECURRENT NOVAE: M31N 2008-12a AND THE IMPLICATIONS OF THE SWIFT NONDETECTION
Authors: Kato Mariko , Saio Hideyuki , Henze Martin , Ness Jan-Uwe , Osborne Julian P. , Page Kim L. , Darnley Matthew J. , Bode Michael F. , Shafter Allen W. , Hernanz Margarita , Gehrels Neil , Kennea Jamie , Hachisu Izumi
Published: October 2016

Models of nova outbursts suggest that an X-ray flash should occur just after hydrogen ignition. However, this X-ray flash has never been observationally confirmed. We present four theoretical light curves of the X-ray flash for two very massive white dwarfs (WDs) of 1.380 and 1.385

and for two recurrence periods of 0.5 and 1 yr. The duration of the X-ray flash is shorter for a more massive WD and for a longer recurrence period. The shortest duration of 14 hr (0.6 days) among the four cases is obtained for the

WD with a 1 yr recurrence period. In general, a nova explosion is relatively weak for a very short recurrence period, which results in a rather slow evolution toward the optical peak. This slow timescale and the predictability of very short recurrence period novae give us a chance to observe X-ray flashes of recurrent novae. In this context, we report the first attempt, using the Swift observatory, to detect an X-ray flash of the recurrent nova M31N 2008-12a (0.5 or 1 yr recurrence period), which resulted in the nondetection of X-ray emission during the period of 8 days before the optical detection. We discuss the impact of these observations on nova outburst theory. The X-ray flash is one of the last frontiers of nova studies, and its detection is essential for understanding the pre-optical-maximum phase. We encourage further observations.
PROBING THE INTERSTELLAR MEDIUM AND STAR FORMATION OF THE MOST LUMINOUS QUASAR AT z = 6.3
Authors: Wang Ran , Wu Xue-Bing , Neri Roberto , Fan Xiaohui , Walter Fabian , Carilli Chris L. , Momjian Emmanuel , Bertoldi Frank , Strauss Michael A. , Li Qiong , Wang Feige , Riechers Dominik A. , Jiang Linhua , Omont Alain , Wagg Jeff , Cox Pierre
Published: October 2016

We report new IRAM/PdBI, JCMT/SCUBA-2, and VLA observations of the ultraluminous quasar SDSS J010013.02+280225.8 (hereafter, J0100+2802) at z = 6.3, which hosts the most massive supermassive black hole (SMBH),

, that is known at z > 6. We detect the [C ii] 158 μm fine structure line and molecular CO(6-5) line and continuum emission at 353, 260, and 3 GHz from this quasar. The CO(2-1) line and the underlying continuum at 32 GHz are also marginally detected. The [C ii] and CO detections suggest active star formation and highly excited molecular gas in the quasar host galaxy. The redshift determined with the [C ii] and CO lines shows a velocity offset of

from that measured with the quasar Mg ii line. The CO (2-1) line luminosity provides a direct constraint on the molecular gas mass, which is about

. We estimate the FIR luminosity to be

, and the UV-to-FIR spectral energy distribution of J0100+2802 is consistent with the templates of the local optically luminous quasars. The derived [C ii]-to-FIR luminosity ratio of J0100+2802 is 0.0010 ± 0.0002, which is slightly higher than the values of the most FIR luminous quasars at z ∼ 6. We investigate the constraint on the host galaxy dynamical mass of J0100+2802 based on the [C ii] line spectrum. It is likely that this ultraluminous quasar lies above the local SMBH–galaxy mass relationship, unless we are viewing the system at a small inclination angle.
DESENVOLVIMENTO DE CALDO DE CANA PASTEURIZADO ADICIONADO DE FRUTAS ÁCIDAS
Authors: Sanda Ana Carla Midori Martins , Silva Adriana Reis de Andrade , Silva Thaísa Lohane da , Orsine Joice Vinhal Costa
Published: October 2016

A adição de concentrados de frutas ácidas ao caldo de cana pode ser uma opção para o consumidor no mercado alimentício de novos produtos. Neste contexto, objetivou-se desenvolver duas diferentes formulações de caldo de cana pasteurizado, adicionado de suco concentrado de limão ou maracujá. Foram realizados testes preliminares, com adição de 5%, 7,5% ou 10% do suco concentrado da fruta (limão ou maracujá) ao caldo de cana. Foi aplicado o teste de ordenação-preferência para cada grupo de amostras referentes ao sabor limão e maracujá, com intuito de verificar a formulação mais preferida. Foram realizadas análises físico-químicas no caldo in natura e nos caldos acidificados, análises de quantificação de minerais, além de análises microbiológicas nos caldos acidificados. O teste sensorial para a escolha das melhores formulações indicou que as concentrações mais preferidas foram aquelas elaboradas com 10% de concentrado se suco de limão e 10% de concentrado de suco de maracujá. Os resultados das análises físico-químicas do caldo in natura comparados com os concentrados foram diferentes, uma vez que as bebidas acidificadas e pasteurizadas apresentaram redução no pH, o teor de sólidos solúveis aumentou nas bebidas processadas em relação ao caldo in natura. Nos testes microbiológicos dos caldos acidificados, ambas as formulações apresentaram-se dentro dos padrões da legislação vigente. A adição dos concentrados de limão ou maracujá ao caldo de cana pode ser considerada uma nova opção ao consumidor, e a pasteurização pode auxiliar na conservação do produto por um maior período de tempo.
RESÍDUOS DA COMERCIALIZAÇÃO DE PESCADO MARINHO – VOLUME DE DESCARTE E ASPECTOS MICROBIOLÓGICOS
Authors: Paulino Leite Suzan Blima , De Arruda Sucasas Lia Ferraz , Oetterer Marília
Published: October 2016

O Município de Santos, SP, apresenta destaque como centro de produção e comercialização de pescado do litoral sul do Estado de São Paulo. Neste local procedeu-se um levantamento e caracterização dos resíduos gerados por ocasião das vendas de pescado, realizadas no mês de agosto de 2013. Utilizou-se um inquérito exploratório em dois centros de venda e observou-se que a principal espécie comercializada e geradora de resíduo foi a pescada amarela, e a quantidade aproximada de resíduos de espécies de pescado, em geral, descartadas por mês foi de, aproximadamente, 20 t, correspondendo a 3.172 kg de proteínas. Nas amostras de resíduos coletadas foram realizadas análises físico-químicas e microbiológicas, detectando-se a presença de micro-organismos termotolerantes em níveis de 0,92x101 a 2,3x101 e mesófilos, da ordem de 1,2x107, acima do permitido pela legislação e que podem indicar riscos ao ambiente e à saúde do consumidor.
Devenir un enfant en danger, épreuves d’âge et de statut
Authors: Perrot Adeline
Published: October 2016

Partant d’une ethnographie sur la définition publique de la catégorie de « mineurs isolés étrangers » en France, l’auteure cherche à éclairer les logiques d’assignation autour de la frontière entre minorité et majorité. Face à ces deux régimes juridiques aux issues contrastées, les opérateurs de jugement et les mijeurs s’inscrivent dans la réalisation d’une limite d’âge difficilement saisissable. L’article fait apparaître les normes relatives à la protection de l’enfance et à la place accordée aux enfants dans la société, par leur opposition naturalisée au monde adulte.
Salut par les œuvres et cohabitation confessionnelle. De l’initiative charitable individuelle à l’organisation ségrégée du contrôle des âmes (Mulhouse, 1798-1870)
Authors: Tournier David
Published: October 2016

Au xix e siècle, les pratiques charitables des élites urbaines s’inscrivent dans le double champ d’une soumission individuelle aux devoirs sotériologiques et de la conformation à des codes culturels dictés par une nouvelle sociabilité bourgeoise. En terrain pluriconfessionnel, ces pratiques s’inscrivent par ailleurs dans une évidente dialectique, les tenants de chaque culte usant parfois de leurs œuvres comme d’une démonstration de leur ancrage respectif. À Mulhouse, cette dialectique communautaire se raidit au fil du siècle, à mesure que les élites protestantes s’éloignent progressivement d’une tentation rationaliste – d’essence philanthropique et sous impulsion municipale – au bénéfice d’un recentrage des œuvres sur les seuls coreligionnaires. L’émulation interconfessionnelle est alors rendue possible par l’émergence tardive d’une élite catholique, désormais à même de s’inscrire dans cette logique concurrentielle.
Harmoniser la lutte antidopage : quelques critiques d’une gouvernance mondiale
Authors: Demeslay Julie
Published: October 2016

L’Agence mondiale antidopage réunit, depuis sa création en 1999, des représentants du mouvement olympique et des pouvoirs publics. Entrant par les critiques formulées à l’égard du fonctionnement de ce modèle paritaire inédit dans le sport, cet article analyse l’articulation difficile des piliers de la gouvernance, des dispositifs standardisés et des pratiques dans la lutte contre le dopage. Ainsi, les objets de dénonciation que sont l’ingérence, le défaut d’expertise et de transparence mais également le milieu insaisissable rendent compte d’une chaîne longue de délégation qui met en cause la prise en considération du local dans un processus normatif globalisant.
Financement du terrorisme et blanchiment de capitaux : liaisons dangereuses ou manipulations d’État ?
Authors: Compin Frédéric
Published: October 2016

Assimiler le financement du terrorisme au blanchiment de capitaux soulève de nombreuses interrogations sur la pertinence de cette relation en raison du faible coût de préparation des attentats et de divergences profondes entre les profils des terroristes par nature reclus et des criminels financiers par essence inclus dans la société. Faut-il voir dans cette association une manipulation utilitariste visant à instaurer une démarche sécuritaire préventive ou le moyen d’annihiler tout esprit critique d’un capitalisme criminogène inducteur de fraude fiscale ?
Une illustration du déclin des particularismes locaux dans le ressort du parlement de Flandre: l’histoire de la famille Saudemont
Authors: Demars-Sion Véronique
Published: October 2016

Lors de sa création, le conseil souverain de Tournai (futur parlement de Flandre) a été érigé en gardien de particularismes locaux que le roi n’a pas tardé à remettre en cause. L’histoire de la famille Saudemont constitue une vivante illustration du déclin de ces particularismes, à la fois institutionnels et juridiques, et de ses conséquences. La création d’une chancellerie et l’introduction de la vénalité des charges au parlement de Flandre ont d’abord servi les ambitions de cette famille en permettant à François-Antoine-Félix de Saudemont de faire l’acquisition d’un office anoblissant mais la condamnation, sous l’influence française, de la jurisprudence locale favorable aux bâtards a ensuite conduit à l’annulation de son testament en faveur de ses enfants illégitimes et à l’attribution de sa succession à son frère qui l’a rapidement dilapidée mettant ainsi un terme brutal et définitif aux rêves de grandeur de sa parenté.
Esthétique et politique de la résistance au travail dans Les Temps modernes
Authors: Debenedetti Stéphane , Huault Isabelle , Perret Véronique
Published: October 2016

Résumé La mobilisation d'une œuvre artistique peut-elle élargir l'horizon des recherches sur les organisations et le travail ? Partant de l'analyse de la figure classique de Charlot au travail dans Les Temps modernes , cet article propose de renouveler le regard posé sur la question de la résistance au travail à travers un film de fiction. En nous appuyant sur la philosophie de Jacques Rancière consacrée au « régime esthétique » de l'art, nous suggérons que les gestes de détournement de Charlot au travail reviennent à ignorer une certaine forme de nécessité qui le forcerait à « rester à sa place », affirmant ainsi une égalité de principe plutôt qu'une rébellion « contre » un ordre dominant. Cette résistance-affirmation, à la fois minuscule et universelle, à l'image du personnage de Charlot lui-même, offre un nouveau regard sur les formes et enjeux de la résistance au travail.
Continuous Curvilinear Capsulorhexis Performed With the VERUS Ophthalmic Caliper
Authors: Kahook Malik Y. , Cionni Robert J. , Taravella Michael J. , Ang Robert E. , Waite Aaron N. , Solomon Jonathan D. , Uy Harvey S.
Published: October 2016

PURPOSE:

To compare size, circularity, and centration outcomes of continuous curvilinear capsulorhexis (CCC) performed with or without assistance from the VERUS ophthalmic caliper (Mile High Ophthalmics, Denver, CO).

METHODS:

This was a multicenter retrospective consecutive case controlled series review.

RESULTS:

Data from 40 consecutive cases using the VERUS device for CCC were compared to 40 consecutive cases with standard manual CCC. VERUS-assisted CCC size, circularity, and centration were closer to target compared to that of manual only procedures (
P
< .05). The average time from initiation to completion of the capsulotomy was shorter with manual (40 ± 11 seconds) compared to VERUS-assisted (71 ± 13 seconds) cases (
P
< .0001).

CONCLUSIONS:

The VERUS ophthalmic caliper is effective at improving size, circularity, and centration of the CCC in a time-efficient manner when compared to manual procedures performed without VERUS guidance.

[
J Refract Surg.
2016;32(10):654–658.]
Study on 3D Edge Crack Extension Simulation in Cold Rolling with the Cohesive Zone Model
Authors: Zan Da Qian , Sun Quan , Pan Hong Liang , Chen Jian Jun , Wang Zheng Dong
Published: October 2016

In the cold rolling process, the edge crack extension can cause the strip rupture completely due to the micro manufacturing defects in the edge. It can greatly impact on the production efficiency and cause the huge economic loss. Thus predicting the edge crack extension behavior becomes important to cold rolling industry. In this paper, a 3D extended finite element method (XFEM) based on the cohesive zone model (CZM) was used to study the edge crack extension under the non-reversing two-high mill cold rolling experiment condition. A bi-linear traction-separation law was utilized which is primarily given by the CZM parameters including the cohesive stress, T0 and the cohesive energy, Γ0. The cohesive stress was determined by hybrid technique of the thin-plate tension test and FEM simulation. The cohesive energy was obtained by the In-Situ SEM three points bending experiment. Different reductions were the mainly analysis factor which can study the extent of the edge crack extension by presetting the edge notch. By comparing the experimental and simulation results, they agreed well with each other. It illustrated that the CZM can provide accurate predictions for the edge crack extension in the cold rolling process. Parametric analysis was carried out and showed that the extent of the crack extension increases with the increasing of the reduction ratio.
Experimental Studies on Deformation Behaviors of Rubbery Materials under Cyclic Loading
Authors: Chen Yi Fu , Kang Guo Zheng , Tao Ru , Jiang Han
Published: October 2016

Macroscopic cyclic tension-unloading experiments are conducted to investigate the cyclic deformation behaviors of CB filled vulcanized hydrogenated nitrile butadiene rubber at room temperature. In the load-controlled cyclic tension-unloading tests, remarkable ratchetting occurs, and the effects of the level and rate of cyclic loading on the ratchetting are also investigated. The ratcheting strain increases with the increasing mean stress and stress amplitude, and more obvious ratchetting is observed in the cyclic test with load-hold or at lower loading rate. In the displacement-controlled cyclic tension-unloading tests, the responding peak stress of the H-NBR decreases continuously, but the residual strain increases with the increasing number of cycles. Furthermore, the zero-stress hold at the end of cyclic test demonstrates that the residual strain will be recovered partially, which implies that the residual strain of the H-NBR after cyclic test consists of the reversible and irreversible parts.
A Comparative Study on the Cyclic Behavior of Austenite/Ferrite Phases Characterized by the Nanoindentation
Authors: Cui Yuan Yuan , Jia Yun Fei , Xuan Fu Zhen
Published: October 2016

The cyclic deformation behavior of the austenite and ferrite phase in an austenite-ferrite duplex stainless steel was studied by using the load-controlled cyclic nanoindentation approach. The results showed that the maximum penetration depth onto both austenite and ferrite phases increased continuously while the rate decreased gradually and finally reached to a constant during the repeated indentation. Both transient state and quasi-steady state were observed for the penetration depth per cycle on both of the austenite and ferrite phases with the increased cycles. By contrast, both the penetration depth and rate per cycle into the austenite phase were larger than those into the ferrite phase. This was ascribed to the stress-induced densification in the austenite and ferrite phases and strain-induced transformed martensite in the austenite phase.
The Mitigation of Weld Residual Stress on 304L Stainless Steel by Post Weld Cool Treatment Process
Authors: Jia Wen Ting , Zhao Jian Ping , Cao Jun
Published: October 2016

The High Welding Residual Stress is the Main Factors Affecting the Service Life of Welded Structures. Post Weld Cool Treatment (PWCT) is a Novel Method by Introducing Reverse Process Welding Temperature Field to Eliminate the Residual Stress and to Obtain Compressive Stress Layer. the Major Factors Affecting the Effects of Post Weld Cool Treatment (PWCT) is Preheating Temperature, Cooling Time and Cooling Range. in this Paper, a Model to Calculate the Residual Stress was Built Using Finite Element Code ABAQUS, and Different PWCT Processes were Applied on 304L Stainless Steel Specimens. at the same Time, Impact Indentation Method (IIM) was Used to Measure the Residual Stress on the Specimens. the Results Show that the Longitudinal Stress and the Transverse Stress were Reduced Obviously and Compressive Stress was Generated after PWCT in both of the Simulation and the Experiment. the Proposal Preheating Temperature was 400°C and the Cooling Range was 2 Times of Weld Width. Besides, the Cooling Time had Little Effect on the Residual Stress.
Numerical Investigation on Creep Crack Growth of Brazed Joint Using Different Damage Models
Authors: Luo Yun , Zhang Qian , Jiang Wen Chun
Published: October 2016

In this paper, four types of creep damage models (Kachanov-Robotnov, Liu-Murakami, Cocks-Ashby and Wen-Tu model) were used to study the creep crack growth (CCG) behavior in compact tension (CT) specimen of Hastelloy C-276/BNi-2 brazed joint. The results show that the creep damage model has a great influence on the CCG behavior of brazed joint. The crack-tip stress states, da/dt-C* curves, crack initiation time and rupture life are different for the different damage models. The Kachanov-Rabotnov model can lead to higher CCG rate and shorter rupture life, while the Cocks and Ashby model can reduce CCG rate and prolong the rupture life. The model order in terms of the CCG rate from high to low is K-R, L-M, W-T, C-A model, which is opposite order of crack initiation time. In the simulation of CCG of brazed joint, a precious damage model should be employed for life prediction.
Numerical Analysis of Wheel Cornering Test Incorporating the Stamping Effects
Authors: Zheng Zhan Guang , Wang Jia Xiang , Xu Xi Yong
Published: October 2016

A reliable but cost-effective method is proposed to improve the FE strength analysis of stamping parts. In the proposed method, a mapping theory of mesh field variables is introduced to eliminate the difference of mesh density in heterogeneous codes using the mesh area of weighting factor method, and a database modification approach is developed to solve the difference of data organization between DYNAFORM and ANSYS. Last, the method is applied in the simulation of car wheel cornering test, the stress states of wheel with and without regard to sheet metal forming effects are comparatively analyzed, and the reliability and validity of the proposed method is verified by the experiment. The further analysis reveals that the thickness change and the residual stress occur during the drawing process of wheel disc, and the stress state of wheel is in asymmetric multi-axial stress during wheel cornering test. It is also revealed that the effect of thickness change on the stress history of steel wheel is different with the effect of residual stress, and their superposition effects are nonlinear with the applied stresses.
Fracture Toughness of Different Locations in API X80 Pipeline Steel on Low Constraint SENT Specimens
Authors: Lu Hong Sheng , Yang Yong He , Chen Gang , Chen Xu , Wang Xin
Published: October 2016

With the considerable use of high-grade pipeline steel in onshore and offshore project, welded joints are recognized as the weak link in pipeline because of the non-uniform microstructural regions induced by welding heat input. At first, the microstructural of different regions in API X80 pipeline welded joints was characterized and quantified by SEM, which indicate that the pipeline steel is a typical acicular ferrite steel. In this paper we investigated the J-integral resistance curve (J-R curve) in different locations of API X80 pipeline welded joints through low constraint SENT specimens with side grooves at room temperature. The effect of notch orientation (longitudinal-radial (L-R) and transverse-radial (T-R)) on resistance curve were investigated in base metal, which reveal the orientation almost have no effect on resistance curve. As the welded joints adopted in this study is two-pass steel arc welds, so the J-R curves of the inner surface, the outer surface and through-thickness surface notches specimens in the weld metal were investigated. The inner surface sample have the highest toughness through three samples because of the effect of second pass welding process. The effect of constraint on resistance curve was conduct between low constraint SENT specimen and high constraint SENB specimen, which found that the lower constraint corresponding to the higher resistance curve. After finishing the test, crack advancing plan of different positions were etched and observed by OM to demonstrate that the crack path always in the region which we would like to test.
Thermal-Mechanical Fatigue Behavior of P92 T-Piece Pipe
Authors: Zhang Wei , Wang Xiao Wei , Gong Jian Ming , Jiang Yong , Huang Xin
Published: October 2016

This paper presents a study on thermal-mechanical fatigue (TMF) behavior of P92 T-piece pipe at the most critical working fluctuations. Pressure and temperature in out-of-phase (OP) and in-phase (IP) conditions were both taken into account. Cyclic plasticity model considering the effect of temperature were used, in which both effects of kinematic hardening and isotropic hardening were included. All of the parameters used in the simulation were obtained from high temperature low cycle fatigue tests (HTLCF). These parameters have been validated through the comparison of experiment data with the simulated data. Then, in order to investigate the effect of OP and IP loadings, thermal-mechanical fatigue finite element model (FEM) of P92 T-piece pipe was also developed. Simulated results reveal that at the most critical working fluctuations, the most dangerous position occurs at the region where the inner surface of horizontal pipe and branch pipe crossed for both IP and OP loadings. With the cycle increases, the equivalent plastic strain is increasing. The peak hoop stress and equivalent plastic strain at IP loading are higher than OP which indicates that IP loadings are more dangerous than OP loadings.
Changes of the Fracture Toughness of ZG40Cr25Ni20 Furnace Tube after Service and the Corresponding Change of the Microstructure of the Fracture Surface
Authors: He Jia Sheng , Hu Xiong , Zhu Xiao Ming
Published: October 2016

According to the principle of fracture mechanics, the fracture toughness of the furnace tube after 30000 hours service and new furnace tube were tested with the MTS810 tester. The microstructure of fracture surface were analysed by the SEM. The results show that the fracture toughness of the furnace tube after service decreases greatly compared with that of the new furnace tube. The microstructure of fracture surface of the furnace tube changes significantly corresponding to the change of the fracture toughness.
Mismatch Constraint Effect for Bimaterial Interfacial Creep Crack
Authors: Dai Yan Wei , Liu Ying Hua , Chen Hao Feng
Published: October 2016

Mismatch effect of weldments is important for the assessment of structural integrity at elevated temperature. The interfacial creep crack is a common model which can be found in lots of engineering practices. Recently, the constraint effect is also considered to be significant for the evaluation of creep crack growth under high temperature. In this paper, a model for bimaterial interfacial creep crack is introduced to study the mismatch constraint effect. The stress field for bimaterial interfacial creep crack is investigated. An M*-parameter is proposed to characterize the constraint effect caused by material mismatch for bimaterial creep crack. A comparison is made between the geometry constraint caused by specimen loading and mismatch constraint caused by inhomogeneous material.
Numerical Investigation of Stainless Steel Welded I-Sections Subjected to Lateral-Torsional Buckling
Authors: Anwar-Us-Saadat Mohammad , Ashraf Mahmud , Ahmed Shameem
Published: October 2016

Stainless steel is now widely used in construction as structural members in recognition to its unique beneficial properties such as corrosion resistance, higher strength and ductility, andnegligible maintenance cost. Recent research on stainless steel has seen development of rational design rules to predict cross-sectional resistances but still lacks in appropriate knowledge at the member level. The current paper investigates the lateral-torsional buckling (LTB) behaviour of welded stainless steel I sections. Available test results were used to develop and validate nonlinear finite element (FE) models. Limited experimental evidences were supplemented by a large number of reliable numerical results covering wider range of member slenderness ratio. All test and numerical results were used to investigate the performance of Eurocode EN-1993-1-4 and Australian code AS/NZS 4673 in predicting member resistances against lateral-torsional buckling.
Structural Integrity Analysis of Nuclear Power Plant Pressure Vessel Penetration Nozzle Repaired
Authors: Ma Lin Wei , He Jia Sheng , Shu An Qing , Zheng Xiao Tao , Wang Yan
Published: October 2016

Primary water stress corrosion cracking (PWSCC) has been observed in CRDM nozzles, BMI nozzles and other penetration nozzles. The industry has used the repair method of replacement of nozzles fabricated of Alloy 690. After the replacement of the nozzle, the structural integrity analysis of new nozzle and welds should be performed to ensure the pressure boundary compliance with the original design requirement. In this paper, the pressurizer top head instrument nozzle of PWR nuclear power plant is evaluated as a typical pressure vessel penetration nozzle. The results showed that the repaired nozzle satisfies the ASME Code design requirement and the crack growth of the postulated flaw in 40 years of the nuclear plant life is acceptable.PWSCC degradation mechanism has been observed in CRDM nozzles, BMI nozzles and other penetration nozzles [1]. In some nuclear power plants built in China earlier, such as DAYABAY nuclear power plant and QINSHAN nuclear power plant, PWSCC degradation mechanism has been found in CRDM nozzle welds which manufactured of Alloy 600 and welded of Alloy 82/182[2]. The repair of the degraded nozzles is the popular choice for the nuclear power plant owners. After the replacement of the nozzle, the structural integrity analysis of new nozzle and welds should be performed to ensure the pressure boundary compliance with the original design requirement. In this paper, the pressurizer top head nozzle of PWR nuclear power plant is evaluated as a typical pressure vessel penetration nozzle. Stress intensities were conservatively determined for pressure and applicable thermal transients and compared to the allowable values of the ASME Code, Section III. Thermal stress of the transients was obtained from 3D finite element model (FEM). Residual stress of J-groove weld was obtained from 2D FEM analysis and used for fracture mechanics analysis. All of the analysis showed that the repaired nozzle satisfies the ASME Code design requirement and the crack growth of the postulated flaw in 40 years of the nuclear plant life is acceptable.
Creep Fatigue Life Assessment of a Pipe Intersection with Dissimilar Material Joint by Linear Matching Method
Authors: Barbera Daniele , Chen Hao Feng , Liu Ying Hua
Published: October 2016

As the energy demand increases the power industry has to enhance both efficiency and environmental sustainability of power plants by increasing the operating temperature. The accurate creep fatigue life assessment is important for the safe operation and design of current and future power plant stations. This paper proposes a practical creep fatigue life assessment case of study by the Linear Matching Method (LMM) framework. The LMM for extended Direct Steady Cycle Analysis (eDSCA) has been adopted to calculate the creep fatigue responses due to the cyclic loading under high temperature conditions. A pipe intersection with dissimilar material joint, subjected to high cycling temperature and constant pressure steam, is used as an example. The closed end condition is considered at both ends of main and branch pipes. The impact of the material mismatch, transitional thermal load, and creep dwell on the failure mechanism and location within the intersection is investigated. All the results demonstrate the capability of the method, and how a direct method is able to support engineers in the assessment and design of high temperature component in a complex loading scenario.
Numerical Study on the Influence of Cathode Flow Channel Baffles on PEM Fuel Cell Performance
Authors: Shen Xiang , Tan Jin Zhu , Li Yun
Published: October 2016

A proton exchange membrane (PEM) fuel cell is an electrochemical device that directly converts chemical energy of hydrogen into electric energy.The structure of the flow channel is critical to the PEM fuel cell performance. In this paper, the effect of the cathode flow channel baffles on PEM fuel cell performance was investigated numerically. A three-dimensional model was established for the PEM fuel cell which consisted of bipolar plates with three serpentine flow channels, gas diffusion layers, catalyst layers and PEM. Baffles were added in the cathode flow channels to study the effect of the cathode flow channel baffle on the PEM fuel cell performance. And then, numerical simulation for the PEM fuel cell with various cathode channel baffle heights ranging from 0.2 mm to 0.6 mm was conducted.The simulated results show that there existed an optimal cathode flow channel baffle height in terms of the electrochemical performance as all other parameters of the PEM fuel cell were kept constant. It is found that the PEM fuel cell had the good electrochemical performance as the flow channel baffle heights was 0.4mm in this work.
Plasma Sprayed Al2O3-SiCw Coatings Deposited under the Electrostatic Field
Authors: Yu Jing Ye , Wang Wei Ze , Wu Liang Min , Feng Zheng Qu
Published: October 2016

Al2O3-SiCw (SiC whisker) powders were plasma sprayed on carbon steel under the electrostatic field. Effect of voltage on the microstructure and mechanical properties of the coatings was investigated. The erosion resistance was measured on the rotating disk erosion tester. The micro hardness and fracture toughness were obtained by the indentation method. It is found that the phase composition is unchanged for the coatings deposited in the presence or absence of electrostatic field while the grain size of coatings varies with the voltage. The porosity of coatings increases with the voltage slightly at first, and then a decrement tendency can be found. The erosion weight loss shows the similar trends with the porosity under the influence of voltage. The fracture toughness is the lowest when the voltage is 10 kV, and it is the highest for coatings deposited under no electrostatic field. The measurement of hardness yields the similar results though the voltage is different. The deflection behaviour of whiskers under the electrostatic field affects the deposition of molten powder and then the microstructure and properties of plasma sprayed coatings.
Measurement of Young’s Modulus of Thermal Barrier Coatings by Suspended Coupled Flexural Resonance Method
Authors: Zhang Shen Zhi , Qi Hong Yu , Yang Hong Wei , Zhang Cheng Cheng , Gao Jing Yun
Published: October 2016

Thermal barrier coatings(TBCs) has been extensively used on hot section components of gas turbine engine, especially turbine blades. Young’s modulus of TBCs is a significant mechanical parameter in life prediction research of turbine blades, but it is hard to measure the EB-PVD thermal barrier coatings by conventional tensile/compression method for its brittleness and porous microstructure. Therefore, Young’s modulus mathematical model of double-layer beam structure specimen was deduced on the basis of the first-order beam bending vibration equation and composite beam bending equation. An experimental platform with dynamic signal acquisition system was set up for measuring Young's modulus of thermal barrier coatings under high temperature. Young's modulus of ceramic coat was measured from ambient temperature to 1100°C to provide material data for subsequent research on life prediction of turbine blades with thermal barrier coatings.
Progressive Failure Analysis of Pipeline Repaired by Composite Wrapping
Authors: Wang Yan Yv , Cheng Zhi Qiang , Liu Bao Sheng
Published: October 2016

Composite overwrap systems have been widely used to repair damaged pipelines. Its effectiveness has been proven by many researches and engineering applications. However, the research on progressive failure mode of the repaired structure has not been reported. In the present paper, finite element method with Hashin failure criteria is developed to realize the progressive failure analysis. The predicted burst pressure is in good agreement with the burst experiment. Different from widely-reported failure progress in Composite Overwrapped Pressure Vessels (COPV), the progressive failure analysis for the defected pipeline overwrapped by composite reveals very different failure stages: stable failure propagation and rapid failure propagation. The identification of critical pressure between these two stages is valuable in composite reparation design for the defected pipeline.
Strain Monitoring via Self-Assembled Quantum Dots
Authors: Zhang Shao Fu , Yin Shao Feng , Luan Wei Ling , Yang Fu Qian
Published: October 2016

Quantum dots (QDs) exhibit unique response of photoluminescence (PL) in response to mechanical deformation, which makes it possible to use QDs-epoxy resin composite in strain monitoring. In this work, gradient concentric rings consisting of QDs are prepared via the evaporation of chloroform droplets on pre-cast QDs/PMMA films, in which rigid spheres are used to pin the chloroform droplets and control the motion of the contact line of the chloroform droplets. Both the distance of adjacent rings (wavelength) and PL intensity are dependent on the size of rings and the thickness of the precast QDs/PMMA films. Using the gradient concentric rings consisting of QDs on the surface of a tensile bar of 304stainless steel, it is found that the distance of adjacent ring varies with tensile strain. This result demonstrates potential applications of self-assembled structures made of QDs in non-contact detection of mechanical deformation.
Failure Analysis of Injection Pipe in Diesel-Hydrogenated Unit
Authors: Fan Li Bo , Zhang Guo Xin , Qu Yan Peng , Liu Yan , Wang Wei Qiang
Published: October 2016

An injection pipe of diesel-hydrogenated unit exploded in a refinery of Shandong Province. In order to analyze the causes of the pipe explosion, the authors measured the pipe wall thickness, sampled the fractured pipe, observed the fracture of the samples by metallographic microscope, surveyed the pipe service environment, and calculated the pipe burst pressure. As the exploded pipe deformed very seriously and no any significant original defect in the fracture was observed, the failure reason of the pipe might be over pressure due to heat tracing by continuous supply of steam during the unit shutdown. Meanwhile, measures were suggested to avoid the similar accidents.
The Effects of Nonproportional Loading on the Elastic-Plastic Crack-Tip Fields
Authors: Jin Zhao Yu , Wang Xin , Yu Dun Ji , Chen Xu
Published: October 2016

In this paper, the loading path effects on the plane strain elastic-plastic crack-tip stress field are investigated computationally. Three different loading sequences include one proportional loading and two non-proportional loading paths are applied to the modified boundary layer (MBL) model under small-scale yielding conditions. For the same external displacement field applied at the outer boundary of the MBL model, the mode I K field and T-stress field combined as the different loading paths are applied to investigate the influence of the nonproportional loading. The results show that for either the compressive or tensional T-stress, the loading path which applied K field followed by T field generates the lower crack-tip constraint. There is only slightly difference between the proportional loading path and that with the T-stress field following by K field. The results show that it is very important to include the load sequence effects in fracture analysis when dealing with nonproportional loading conditions.
Preparation of Al6061-SiC with Neem Leaf Ash in AMMC’s by Using Stir Casting Method and Evaluation of Mechanical, Wear Properties and Investigation on Microstructures
Authors: Prasanna S.C. , Ramesh C. , Manivel R. , Manikandan A.
Published: October 2016

Aluminum Metal Matrix Composites (AMMCs) are promising materials for advanced structural, aviation, aerospace, marine, defense applications, automotive and other related sectors because of their excellent combination of properties. The AMMCs is fabricated by using stir casting method, which is the simplest way of fabricating a material. In this paper aluminium alloy 6061 is been reinforced with SiC along with fly ash and neem leaf ash. The three samples have been fabricated they are Sample1 (Al85%+SiC15%), Sample2 (Al 85%+SiC5%+FlyAsh10%) & Sample3 (Al85% +SiC5%+ Neem leaf ash10%). After fabricating this three sample the following test are conducted like Hardness test, Microstructure Test, Friction and Wear Test. The wettability of SiC and Neem leaf ash particles in the matrix was improved by adding them. The optical and scanning electron micrographs showed a homogeneous dispersion of composition material. The result shows that the Sample-3 (Al80% +SiC10%+ Neem leaf ash10%) shows improvement in mechanical properties like hardness, the wear properties has been reduced and their Micro structural characterization clearly shows uniform distribution of SiC and Neem Leaf ash in the composition.
Experimental and Analytical Studies on Magnetorheological Damper
Authors: Lohit S.K. , Hemanth K. , Kumar Hemantha , Gangadharan K.V.
Published: October 2016

This paper presents experimental and analytical study of magnetorheological damper. The experimental study has been conducted at 1.5 Hz frequency with varying current values by using hydraulic dynamic testing facility. The Bhingam MR damper model has been adopted to predict nonlinear hysteretic behaviour of magnetorheological (MR) damper and compare the results with experimental investigations. The result shows, good agreement between them.
An Ant Colony Optimization Algorithm for Cellular Manufacturing System
Authors: Kamalakannan R. , Sudhakara Pandian R. , Sornakumar T. , Mahapatra S.S.
Published: October 2016

In this paper, an ant colony algorithm is used to solve the machine part cell formation problem based on the machine – index - based local procedure and part assignment rule for the better clustering of machines in to machine cells and parts in to part families. The main objective of this paper is to increase the grouping efficacy which is one of the good performance measures for the cell formation problem. The performance assessment of the ant colony algorithm was carried out by testing with the benchmark problems from the literature. From this assessment it clearly shows that this machine index based local procedure is capable to solve the machine part cell formation problem efficiently.
Mathematical Modeling of Surface Roughness during Drilling of Resin Hybrid GFRP Composites
Authors: Desikan B. , Jenarthanan M.P.
Published: October 2016

The preparation, characterization and machinability of resin hybrid GFRP composites are presented in this paper. It is made up of Glass fiber and the mixture of epoxy and polyester resin. It was prepared by the traditional layout technique with the usage of Glass fiber. The weight percentages of GFRP are 0, 20 and 40 having the composition of polyester and epoxy resins. The study of ASTM revealed the variation of break loads and shear strength for three different combinations of epoxy and polyester resins. The main disadvantage of this method is that it resulted in poor dimensional stability and surface roughness. Our main goal was to minimize the surface roughness. There are certain drilling parameters such as composite material, point angle, spindle speed and feed rate during drilling of resin hybrid GFRP which are to be focused to minimize the surface roughness. The experiments were conducted and the results were obtained using Taguchi’s L9 orthogonal array design. It was further analyzed using Signal-to-noise Ratio. Investigating the cutting characteristics of Resin hybrid GFRP proved to be mandatory. This was done by using the Analysis of variance (ANOVA). The Minitab 15 software was used to determine the correlation by linear Regression methods. The value obtained was subjected to a recheck to check the percentage error. The percentage error between the experimental and theoretical value was minimal.
Comparative Study on Mechanical Properties of GMA Welded IRSM41 Mild Steel Plate Based on Grain Flow Direction
Authors: Megavarnan R. , Rajamurugan G. , Shanmuga Prakash R.
Published: October 2016

The purpose of this work was to study the mechanical properties of GMAW welded IRSM41 material based on the grain flow directions. It is a joining process that fuses the base metal to make the weld. The results were analyzed by means of the mechanical properties such as tensile strength, bend test, microstructure and hardness was carried out for both along and across the grain flow direction of the weldments. The important implication about grain flow is that some mechanical properties vary with respect to orientation of the grain flow. The strength and hardness are primarily varied based on the grain flow direction. The desirable properties associated with retarding crack propagation can see significant differences depending on the grain flow and the direction of the moving crack. So, properties like fatigue strength, impact toughness and ductility, which are measures of a material’s resistance to cracking (measured after fracture), can be significantly improved if the crack propagation direction and the grain flow are properly aligned. The optimum alignment occurs when the maximum principal stress (perpendicular to a potential crack or fracture) is aligned with the grain-flow lines. On testing the mechanical properties, it reveals that along the grain flow direction has 13.5% higher than the across the grain flow direction.