bluuebunny/crossref_metadata_2025 huggingface dataset:
Seule une politique de développement qui profite à la population nous protégera du vote Front national
Authors: Braouezec Patrick
Published: October 2016

Le projet du Grand Paris est plutôt positif pour la Seine-Saint-Denis avec la construction du nouveau métro et le désenclavement de l’est du département. La création de la Métropole est plus critiquable : elle ajoute une nouvelle strate de gouvernance, recentralise les politiques d’aménagement et pour le moment se traduit par le gel de nombreux projets. Il va falloir la faire évoluer pour qu’elle devienne une structure souple, stratégique, à même de définir un certain nombre de politiques communes, mais aussi l’étendre à l’ensemble de l’agglomération et redonner aux intercommunalités de base, les territoires, le statut d’EPCI et l’autonomie qui va avec. C’est d’autant plus nécessaire que la participation politique est en crise, ici plus encore qu’ailleurs : l’abstention est très élevée, les partis ont été longtemps réticents à présenter des candidats issus de l’immigration. Il faut inventer d’autres formes politiques pour remplacer les partis, devenus obsolètes, tout en laissant aux élus le rôle de porter les projets et d’écrire un récit que la population puisse s’approprier.
Un territoire tremplin ? La politique de la ville en trompe l’œil
Authors: Estèbe Philippe
Published: October 2016

La Seine-Saint-Denis est un territoire abonné aux politiques de la ville depuis plus de trente ans. Pour autant, les différentes interventions, particulièrement celles portant sur le logement, ne sont pas parvenues à engendrer une évolution visible de la structure sociale de la population, ni à changer significativement les qualifications et les professions des habitants. Faut-il pour autant en conclure, comme il est d’usage, à l’échec de la politique de la ville ? Une analyse socioéconomique du département montre qu’il assume une fonction massive d’accueil des ménages populaires et immigrés, et que cette spécialisation n’empêche pas ses habitants d’accéder à l’éducation, à l’emploi et même de suivre des itinéraires résidentiels hors du territoire. Si le profil social est resté stable, voire s’est accentué, les individus ont bougé. C’est dans cette capacité à faire fonctionner le département comme un territoire tremplin qu’il faut juger de l’efficacité de la politique de la ville en Seine-Saint-Denis.
La concurrence peut-elle sauver les chemins de fer européens ?
Authors: Messulam Pierre
Published: October 2016

Le mal des chemins de fer européens touche à la nature de ce mode de transport, conçu dès l’origine par l’État autant comme un vecteur de développement industriel que comme un outil de cohésion nationale. Il faut maintenant repenser son rôle et son lien à la Nation.
Les usages des manuels dans les préparations des enseignants stagiaires
Authors: Scheepers Caroline
Published: October 2016

La présente contribution se propose d’analyser la façon dont les manuels sont convoqués par les stagiaires dans leurs préparations de cours de français. Dès lors, la focalisation se place non sur les manuels en tant quel tels, mais sur leur réception et leur réinvestissement dans les pratiques des étudiants. Ont été analysées une centaine de fiches de préparation élaborées par de futurs enseignants belges, qu’ils se destinent à enseigner au primaire, au secondaire inférieur (collège) ou supérieur (lycée). Les usages du manuel révèlent et construisent des différences notables en termes de compétences enseignées, de gestes pédagogiques mobilisés, de rapport au savoir, de culture professionnelle, de formation… Étudier la réception et l’utilisation du manuel revient à problématiser des pratiques et des représentations fondamentales qui touchent à ce que veulent dire enseigner, (faire) apprendre ou construire une leçon. Cette recherche éclaire une facette du processus de planification des apprentissages.
Le péché d’ Acedia , de l’aversion à l’indifférence
Authors: Giangiobbe Julie
Published: October 2016

Cet article aborde le péché capital d’ acedia ou acédie, pour déterminer s’il se caractérise plus essentiellement comme aversion ou comme indifférence . À partir de sa figure originaire, livrée par le théologien-ermite Évagre le Pontique, sera dépassée sa formulation comme odium professionis , haine de l’état monastique, au profit d’une hypothèse mettant en jeu à la fois indifférence et aversion, celle de l’insupportable indifférence. Cette hypothèse sera ultimement dépassée par la mise au jour d’un état plus profond d’indifférence à soi, menant à la thèse ultime, kierkegaardienne, d’une défaillance éthique profonde dans l’acédie.
Aspheric Micro-monovision LASIK in Correction of Presbyopia and Myopic Astigmatism: Early Clinical Outcomes in a Chinese Population
Authors: Zhang Ting , Sun Yuan , Weng Shengbei , Liu Manli , Zhou Yugui , Yang Xiaonan , Stojanovic Aleksandar , Liu Quan
Published: October 2016

PURPOSE:

To analyze early clinical outcomes of aspheric micro-monovision LASIK for correction of presbyopia and myopia with or without astigmatism.

METHODS:

Prospective, non-comparative case series of 80 eyes of 40 patients with a mean age of 43.4 ± 4.9 years (range: 38 to 63 years) treated bilaterally using an aspheric micro-monovision protocol. The target refraction was plano for the distance eye and between −0.75 and −2.25 diopters (D) for the near eye. Visual acuity, ocular aberrations, contrast sensitivity, corneal topography, amplitude of accommodation, binocular sensorial function, and satisfaction score questionnaires were evaluated at 3 months after surgery.

RESULTS:

Three months after surgery, the mean spherical equivalent (SE) refraction in the distance eye was −0.08 ± 0.27 D, whereas the attempted and achieved SE in the near eye were −1.41 ± 0.28 and −1.32 ± 0.35 D, respectively. Ninety-three percent of eyes were within ±0.50 D of target correction of SE. The uncorrected distance visual acuity (UDVA) after surgery was −0.10 ± 0.06 logMAR (20/15.5), 0.22 ± 0.12 logMAR (20/34), and −0.11 ± 0.06 logMAR (20/15), for distance eyes, near eyes, and binocularly, respectively. Ninety-five percent of patients achieved simultaneously uncorrected distance visual acuity 0.0 logMAR (20/20) or better and uncorrected near visual acuity J2 (20/25) or better. Stability was achieved from 1 week of follow-up. The overall satisfaction score for surgery was 92 ± 6.

CONCLUSIONS:

The aspheric micro-monovision protocol provided a well-tolerated and effective means for treating myopic astigmatism and alleviating presbyopic symptoms simultaneously.

[
J Refract Surg.
2016;32(10):680–685.]
A Pilot Study of SMILE for Hyperopia: Corneal Morphology and Surface Characteristics of Concave Lenticules in Human Donor Eyes
Authors: Zhao Jing , Miao Huamao , Han Tian , Shen Yang , Zhao Yu , Sun Ling , Zhou Xingtao
Published: October 2016

PURPOSE:

To evaluate the corneal morphology and surface characteristics of concave lenticules after small incision lenticule extraction (SMILE) for hyperopia.

METHODS:

SMILE procedures were performed on two human autopsy corneas in vitro to correct +4.00 diopters of hyperopia. Slit-lamp microscopy and anterior optical coherence tomography (OCT) were performed after lenticule creation and extraction. The extracted lenticules and modified corneas were sent for transmission electron microscopy imaging.

RESULTS:

Interlamellar gas bubbles were detected at 3 minutes and almost burst at 30 minutes after lenticule creation. A few interlamellar bubbles were detected after lenticule extraction. There was an obvious interlamellar concave gap under OCT. Transmission electron microscopy showed the front and back surfaces of the lenticules were smooth, with some tissue bridges, cavities, and grooves.

CONCLUSIONS:

A good quality concave lenticule can be created via SMILE for hyperopia. The impact of interlamellar gap on visual quality needs further investigation.

[
J Refract Surg.
2016;32(10):713–716.]
Short-term Variance of Refractive Outcomes After Simultaneous LASIK and High-Fluence Cross-linking in High Myopic Correction
Authors: Chan Tommy C. Y. , Yu Marco C. Y. , Ng Alex L. K. , Cheng George P. M. , Zhang Jiamei , Wang Yan , Jhanji Vishal
Published: October 2016

PURPOSE:

To analyze the visual and refractive outcomes of LASIK with and without simultaneous cross-linking for correction of myopia.

METHODS:

Patients who received femtosecond laser-assisted LASIK with and without adjunctive cross-linking according to patient's preference were examined longitudinally for 6 months. Patients with myopic manifest refraction spherical equivalent of 5.00 diopters (D) or greater and estimated residual stromal thickness of greater than 250
µ
m were included.

RESULTS:

Overall, 120 eyes of 60 patients were included (60 eyes of 30 patients for LASIK with cross-linking; 60 eyes of 30 patients with LASIK only). No significant difference was observed in age, preoperative corrected distance visual acuity, manifest refraction spherical equivalent, manifest sphere and cylinder, minimal corneal thickness, and residual stromal bed thickness between both groups (
P
≥ .245). The uncorrected distance visual acuity and efficacy index were significantly worse on day 1 in eyes receiving adjunctive cross-linking (
P
= .0001). At 6 months, 86.7% and 95% of the eyes achieved uncorrected distance visual acuity of 20/25 or better in LASIK with cross-linking and LASIK only, respectively. The variance of postoperative spherical equivalent and sphere was significantly higher in eyes undergoing LASIK with cross-linking from 1 week up to 6 months compared to LASIK only (
P
≤ .002). None of the patients required re-treatment up to 6 months postoperatively.

CONCLUSIONS:

Adjunctive cross-linking during LASIK was associated with worse visual outcomes during the first postoperative week. The variance of spherical equivalent was also high in these patients over a 6-month follow-up.

[
J Refract Surg.
2016;32(10):664–670.]
A Workload Assignment Strategy for Efficient ROLAP Data Cube Computation in Distributed Systems
Authors: Suh Ilhyun , Chung Yon Dohn
Published: October 2016

Data cube plays a key role in the analysis of multidimensional data. Nowadays, the explosive growth of multidimensional data has made distributed solutions important for data cube computation. Among the architectures for distributed processing, the shared-nothing architecture is known to have the best scalability. However, frequent and massive network communication among the processors can be a performance bottleneck in shared-nothing distributed processing. Therefore, suppressing the amount of data transmission among the processors can be an effective strategy for improving overall performance. In addition, dividing the workload and distributing them evenly to the processors is important. In this paper, the authors present a distributed algorithm for data cube computation that can be adopted in shared-nothing systems. The proposed algorithm gains efficiency by adopting the workload assignment strategy that reduces the total network cost and allocates the workload evenly to each processor, simultaneously.
Unified Constitutive Modeling towards Enhanced Structural Integrity
Authors: Hassan Tasnim , Ahmed Raasheduddin , Barrett Paul R. , Islam Nazrul , Morrison Machel L.
Published: October 2016

Design and analysis of critical components in energy (nuclear, solar and fossil power), aerospace, automobile and chemical industries based on detailed inelastic analysis can enhance structural integrity and thereby economy. Especially for the components exposed to very high temperature thermomechanical fatigue loading, unified inelastic analysis based life prediction may enhance accuracy. A unified constitutive model (UCM) with features of strain rate-dependence, static recovery, mean-stress evolution, strain range-dependence, and finally creep damage is developed. The modified UCM is validated against simulating a broad set of strain-controlled isothermal and anisothermal fatigue and fatigue-creep responses, and stress-controlled creep responses of Haynes 230. Some of these results are presented to demonstrate improved simulations by the modified UCM. Importance of damage parameters in improving simulations in the tertiary creep regime is observed.
Three Dimensional Criterion for Creep Crack Propagation in C(T) Specimen
Authors: Ye Wen Ming , Hu Xu Teng , Guo Wan Lin , Song Ying Dong
Published: October 2016

Experimental of two kinds of compact tension (CT) specimens’ creep crack propagation are carried out in this paper. Traditional fracture mechanics and three-dimensional fracture theory are compared and the results show that: The K-Tz two-parameter model can eliminate the thickness-effect on the crack growth rates in the relatively low K range, however when K exceed certain values the effect of thickness for crack growth rates still exists; The Ct and Ct-Tz model can describe the thickness-effect of creep crack growth rates in regions of high Ct; When the crack tip stress intensity factor K of the two kinds of thickness (B=5 mm, B=10 mm) specimens equal to 35 and 31 respectively, this material’s creep crack growth control parameter change from K to Ct.
Long Time High Temperature Stress Rupture Strength Behavior and Structure Stability Study on Ni-Base Superalloy Nimonic 80A
Authors: Chen Xiao Fei , Yao Zhi Hao , Zhang Mai Cang , Xie Xi Shan , Yu Qiu Ying , Song Jing Jing , Ding Li Feng , Shen Hong Wei
Published: October 2016

Nimonic 80A Ni-base superalloy can be used for high temperature steam turbine components.There is a critical requirement for turbine blade application that the stress rupture strength for 105 hrs at relevant high temperatures should be higher than 100MPa.On the other hand, it must keep good structure stability and no harmful phase such as-phase and the TCP phase formation at long time high temperature exposure. Therefore, the long time stress rupture tests at temperatures of 600, 650, 680 and 700°C for different stresses have been carried out. The long time structure stability has been also studied in detail. The results show that Nimonic 80A can meet the critical requirement for USC steam turbine blades at 600~700°C. Any detrimental phases have not been found at the long time stress rupture tests. The morphology of grain boundary carbides also has no apparent change. Based on above mentioned results, Nimonic 80A is recommended to be used for USC steam turbine components in the temperature range of 600~650°C.
Establishment of Unified Correlation of In-Plane and Out-of-Plane Constraints with Ductile Fracture Toughness of Steel
Authors: Yan Bo Rui , Wang G.Z. , Xuan Fu Zhen , Tu Shan Tung
Published: October 2016

In this paper, the finite element method (FEM) based on GTN damage model was used to obtain ductile fracture toughness and investigate the establishment method of unified correlation of in-plane and out-of-plane constraints with ductile fracture toughness of steels. The unified constraint parameter Ap at different equivalent plastic strain (εp) isolines has been calculated and analyzed for SEN(B) specimens with a wide range of in-plane and out-of-plane constraints. The results show that the average Ap along the specimen thickness (Apave) can well characterize a wide range of in-plane and out-of-plane constraints. The suitable εpisolines range for establishing the unified correlation between Apave and ductile fracture toughness of the steel has been obtained. For the specimens with lower constraint, the higher εp values should be used. The results also show that the correlation line of JC/Jref-Apave1/2is independent of the selections of the suitable εp isolines and the reference specimen. This may bring convenience for the establishment and application of the JC/Jref-Apave1/2correlation lines. Using ductile fracture toughness data of a small number of specimens with different constraints (such as three specimens with different a/W) together with FEM calculations of the parameter Ap, the correlation line of JC/Jref-Apave1/2can be established. The correlation line may be used in structural integrity assessments incorporating both in-plane and out-of-plane constraints.
Numerical Investigation on Plastic Strain Correction Factor in Simplified Elastic-Plastic Fatigue Analysis
Authors: Kan Qian Hua , Guo Su Juan , Li Jian , Kang Guo Zheng , Yan Wen Yi
Published: October 2016

A plastic strain correction factor is used in a simplified elastic-plastic fatigue analysis of nuclear power plant components. Numerical investigation on the plastic strain correction factor is presented for the case of the primary and secondary stress range exceeding three times the design stress intensity value under thermal-mechanical loadings. The plastic strain correction factor was computed separately by following the RCC-M code and applying the elastic-plastic finite element analysis. The influence of loading ratio, loading controlled mode and ambient temperature on the plastic strain correction factor was discussed. It was shown that the plastic strain correction factor computed from the RCC-M code is not as conservative as that from the complete elastic-plastic finite element analysis when the primary plus secondary stress range is close to three times the design stress intensity value. However, it is too conservative when the primary plus secondary stress range is more than three times the design stress intensity value multiplying parameter m (use in RCC-M code). Additionally, a new formula of plastic strain correction factor was proposed to provide a complete envelope curve to the entire primary plus secondary stress range.
Uniaxial Ratcheting and Low-Cycle Fatigue Failure of U75V Rail Steel
Authors: Fang Tao , Kan Qian Hua , Kang Guo Zheng , Yan Wen Yi
Published: October 2016

Experiments on U75V rail steel were carried out to investigate the cyclic feature, ratcheting behavior and low-cycle fatigue under both strain- and stress-controlled loadings at room temperature. It was found that U75V rail steel shows strain amplitude dependent cyclic softening feature, i.e., the responded stress amplitude under strain-controlled decreases with the increasing number of cycles and reaches a stable value after about 20th cycle. Ratcheting strain increases with an increasing stress amplitude and mean stress, except for stress ratio, and the ratcheting strain in failure also increases with an increasing stress amplitude, mean stress and stress ratio. The low-cycle fatigue lives under cyclic straining decrease linearly with an increasing strain amplitude, the fatigue lives under cyclic stressing decrease with an increasing mean stress except for zero mean stress, and decrease with an increasing stress amplitude. Ratcheting behavior with a high mean stress reduces fatigue life of rail steel by comparing fatigue lives under stress cycling with those under strain cycling. Research findings are helpful to evaluate fatigue life of U75V rail steel in the railways with passenger and freight traffic.
Peak Load Response of a Concrete Beam in Mixed-Mode Fracture
Authors: Guo Xiang , Su Ray K.L. , Young Ben
Published: October 2016

A major difficulty in simulating load response of a concrete structure in mixed-mode fracture lies in the fact that crack path is not known a priori. Predicting both the crack path and the associated load response involves advanced simulation techniques and novel numerical methodologies. Here, an intrinsic cohesive crack model is employed to study mixed-mode fracture in a concrete beam. The present approach requires neither preliminary results from linear elastic fracture mechanics simulations nor a re-meshing procedure or special implementation to prevent crack locking. Simulations with regular meshes illustrate that this concise approach can provide a reasonable estimation of peak load of the pre-cracked concrete beams in mixed-mode fracture. This study shows that the energy ratio in the bilinear softening law has larger effects than the stress ratio.
Stress Analysis for Clad Steel Tube Sheet with Oval Tube Hole
Authors: Wang Ke , Xu Wei Feng , Liu Zun Chao , Liu Min Shan
Published: October 2016

Models are established for oval tube hole clad steel tube sheet and circular tube hole clad steel tube sheet. Finite element analysis software ANSYS Workbench is used. Stress distribution characteristics of tube sheet with oval tube hole are investigated. Stress distribution characteristics under different ellipticity are analyzed and the general law of stress distribution of oval tube hole clad steel tube sheet is summarized. Results show: effects of tube hole shape on stress of clad steel tube sheet mainly focus in the tube zone, oval tube hole could effectively improve the phenomenon of stress concentration at the connection of basic layer and clad layer. When tube hole is oval, the maximum values of thermal stress and mechanical stress increase comparing to clad steel tube sheet with circular tube hole. With the increase of ellipticity, the total stress of tube sheet increases, stress increases on the minor axis of tube hole and decreases on long axis, and the deviation between the two stresses increases. The results provide reference for the design of the clad steel tube sheet.
Study on the Prediction of the Maximum Crack Extension Location for Surface Cracks
Authors: Yang Jie
Published: October 2016

In this paper, the plate with different surface cracks (different constraints) was selected, the finite element numerical simulation method was used to mod el the J-integral and the equivalent plastic strain (εp) distributions ahead of crack front, after the unified constraint characterization parameter Ap was calculated, a new parameter which considered both J-integral and constraint effectwasdefined and a new methodology was provided to ensure the maximum crack extension location of surface crack. The results show that if the location of the maximum is defined as the maximum crack extension location, the prediction results is consistent with the measured results in experiments. The parameter which considered both crack driving force and material resistance force is a suitable parameter, and can be used to predict the maximum crack extension location.
Buckling Behaviour of Stainless Steel Square Hollow Sections
Authors: Ahmed Shameem , Ashraf Mahmud , Anwar-Us-Saadat Mohammad
Published: October 2016

Structural stainless steel design guidelines should appropriately recognise its characteristic beneficial properties such as material nonlinearity and significant strain hardening. The Continuous Strength Method (CSM) exploits those through a strain based approach for both stocky and slender cross-sections. In this paper, a new design method is proposed that combines the CSM with Perry type buckling curves. Numerical models were developed to investigate effects of various parameters on column strength and to develop full column curves. It was observed that material nonlinearity significantly influence column strengths, and hence, different column curves were developed for a total of 20 material property combinations by calibrating imperfection factor and limiting slenderness ratio for each set. Proposed method includes the strain hardening benefits for stocky section, and abolished the necessity of calculating effective cross-sectional properties for slender sections. Performance of the proposed technique is compared against those obtained by the Eurocode EN1993-1-4.
The Study on Degradation of Stainless Steel Clad Plate Used for a Shift Reactor in Coal Chemical Plant
Authors: Pan Qing , Tan Jin Zhu , Feng Qiu Yue , Li Yun , He Ri Dong
Published: October 2016

Shift reactors are widely used in the petroleum and chemical industries, and especially in the coal chemical plants. The degradation of the reactor is critical to the safe operation of coal chemical plant. In this paper, a shift reactor after 8 year service was chosen. The test block taken from the reactor cylinder with the stainless steel clad plate was used and the test samples from the test block were prepared. And then, chemical composition analysis, metallographic examination, tensile and hardness tests were performed. The scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) method were used to study the degradation and degradation mechanism of the reactor. The metallographic analysis results show that there were a large number of carbides segregated in the grain boundary and the intergranular cracks were observed for the samples in the weld zone of the stainless steel clad plate. The SEM and EDS results indicate that the corrosion medium (i.e. polythionic acid) was found in the fracture surface of the samples from the weld zone of the stainless steel clad plate. The XRD test results show that the tensile residual stress occurred for the welding of the stainless steel clad plates. It is found that the degradation mechanism of the shift reactor was due to the polythionic acid stress corrosion cracking.
Ratcheting Behavior of Pressurized Elbow Pipe under Different Loading Modes
Authors: Qu Wei Qiang , Chen Xu
Published: October 2016

Ratcheting deformation is studied on elbow pipe made of Z2CND18.12N by FEM software. The simulation is conducted by ANSYS. Chen-Jiao-Kim (CJK) kinematic hardening model is added in ANSYS for the study. The elbow pipe is subjected to internal pressure and reversed in-plane bending. Internal pressure can be constant or cyclic. Many different loading paths are used in the study. Ratcheting deformations of under different ways are studied. The result shows that ratcheting deformation occurs mainly in the circumferential direction. Ratcheting deformation at the crown and intrados of elbow pipe is more notable because of higher stress. Tensile or compressed load can influence the position of dangerous point. It is found that ratcheting deformations under different paths with same peak load are different.
Discussion on the Implementation of the Primary Structure Method in Design by Analysis
Authors: Duan Cheng Hong , Ding Li Wei , Lu Ming Wan
Published: October 2016

The implementation of the primary structure method in design by analysis of pressure vessel is discussed. With two examples of axisymmetric structure of pressure vessel, flat head-cylindrical shell joint and flange-ellipsoidal head joint, the primary structure is constructed according to the principle of this method with ANSYS. By comparing the stress intensity and deformation of the primary structure with that of the original structure, the primary and secondary stress along the stress classification line can be clearly distinguished by using the primary structure method. It has great application value in dealing with stress classification in the elastic stress analysis method. The results also show that a variety of reasonable primary structures can be constructed based on the same original structure, and the primary structure method has some flexibility.
Stress Corrosion Cracking of NiCrMoV Steel Welded Joint under Applied Load in Simulated Environment of Low Pressure Nuclear Steam Turbine
Authors: Weng Shuo , Huang Yu Hui , Xuan Fu Zhen , Luo Ling Hua
Published: October 2016

In order to determine the stress corrosion cracking susceptibility of NiCrMoV steel welded joint of low pressure nuclear steam turbine, long time immersion tests had been carried out in the form of cylindrical tensile specimens self-loaded to various applied load (0, 0.3YS, 0.6YS and 0.9YS) and exposed in the simulated environment with 180°C, 3.5% NaCl. Coarsen grain heat affected zone reacted preferentially as anode in welded joint, which was caused by the synthetic effects of micro-galvanic corrosion, much more precipitations of carbides and higher content of Cr element. Preferential local corrosion of coarsen grain heat affected zone with the formation of occluded corrosion cell accelerated corrosion rate. In addition, the dissolution rate also increased as the applied load increased.
Stress Analysis for the Orthotropic Pressurized Structure of Cylindrical Shell with Nozzle
Authors: Zhang Jing , Zhou Chang Yu , He Xiao Hua
Published: October 2016

The structure of cylindrical shell with nozzle has been widely used in pressure equipment. The analysis and design for the structure of cylindrical shell with nozzle are generally based on the isotropy of metal at present, which may cause certain error and risk. Because of the approaches of rolling, heat treatment, and so on, the materials’ properties are different along each direction in practical engineering. In this paper, based on anisotropic thin shell theory, the analysis for orthotropic pressurized structure of thin-walled cylindrical shell with nozzle was conducted by using finite element software Ansys. The influences of thickness ratio and elastic modulus ratio were comprehensively considered, and also compared with the stress results under isotropic structure. The analysis results show that the values of stress and stress concentration factor for the structure of cylindrical shell with nozzle decrease with elastic modulus ratio, but increase with thickness ratio. Compared with the influence of thickness ratio, the elastic modulus ratio has significant effect on stress level. The rational use of the material anisotropic property can optimize the structure of thin-walled cylindrical shell with nozzle. The results in present paper provided a reference for the design of orthotropic pressurized structure of cylindrical shell with nozzle.
The Significance of Thermo-Mechanical Fabrication on Long Term Creep Life of Type 316H Austenitic Stainless Steel Components
Authors: Martinez-Ubeda Ana Isabel , Warren Alexander D. , Griffiths Ian , Flewitt Peter E.J.
Published: October 2016

The UK’s Advanced Gas Cooled Reactor (AGR) nuclear power generating plant operates at temperatures up to 550 °C, where creep life is important. We consider Type 316H austenitic stainless steel headers and tubes with thermo-mechanical fabrication histories that result in significantly different initial microstructures. The heat affected zone of weldments, in these thick section headers and thin walled boiler tubes, have been found to be susceptible to creep damage leading to cracking during service. In this work we explore these differences in the long term service aged microstructure and the link to overall creep life of these components. To achieve this, samples containing weldments have been removed from plant after extended periods of service. Specifically parent and HAZ regions have been examined to determine the types of precipitates arising from the long term ageing. In particular, thin foils have been examined in a JEOL ARM transmission electron microscope operating at 200KeV fitted with an Oxford Instruments energy dispersive spectrometer to allow comparison between high resolution images and chemical composition. The thin foils were removed from predetermined locations using gallium ion milling and finally thinned using a low ion current to minimise ion damage. Differences between the distributions and types of precipitates are considered in the context of the initial microstructure arising from the thermo-mechanical history on the loss of creep strength and initiation of creep cavities at grain boundaries. The impact on overall service life is addressed.
Effect of Temperature and Environmental Aging on the Mechanical Reliability of n- and p-Type Thermoelectric Couples
Authors: Tan Yan Song , Chen Xu
Published: October 2016

Bismuth telluride-based alloys are the most widely used thermoelectric materials, which can obtain the conversion between heat energy and electricity. As a kind of lead-free solder alloy, Sn96.5Ag3.0Cu0.5 (SAC305) shows great potential in soldering between the thermoelectric element and electrode in thermoelectric couples. Cu/ SAC305 /Ni-plated Bi0.5Sb1.5Te3 (n-type) and Cu/ SAC305/Ni-plated Bi1.8Sb0.2Se0.15Te2.85 (p-type) couples were connected at 250°C by reflow soldering to investigate effects of temperature and thermall aging on the efficiency and reliability of thermoelectric device. Effects of temperature and environmental aging on shear force of thermoelectric couples were studied respectively in the temperature range of 20°C to 180°C. At room temperature of 20°C, n-type thermoelectric couples showed higher shear force than p-type thermoelectric couples. N-type thermoelectric couple showed higher shear reliability than p-type thermoelectric couples after synchronized environmental aging. The shear force of both types of thermoelectric couples decreased with the growth of thermal aging cycles. Finally, the fracture surfaces of two types of thermoelectric couples were investigated respectively using SEM to further analyse the failure mechanism.
The Influence of Processing Parameters on the Surface Integrity of Ni60A Coatings Fabricated by Laser-High Frequency Induction Hybrid Cladding
Authors: Lu Shu Hua , Ling Xiang , Zhang Jin Chun
Published: October 2016

The surface of much equipment that employed in petrochemical industry is always damaged by corrosion. As a novel technology, laser-high frequency induction hybrid cladding is an effective surface modification technology. Processing parameters, such as laser power, laser scanning speed and induction heating temperature, play an important part in the structural integrity of the coatings. The effects of these processing parameters to cladding integrity were investigated in this paper. Nickel base alloy (Ni60A) claddings were fabricated on the surface of low alloy steel by the way of laser-high frequency induction hybrid cladding and coaxial powder feeding. Macroscopic appearance and porosity of the claddings were systematically investigated by optical microscopy. The corrosion resistance of specimens manufactured by the optimum processing parameters is evaluated in 3.5% NaCl solution by electrochemical test. As the change of processing parameters, the width, height and porosity of laser claddings had an obvious change. Optimum processing parameters was determined because of the overall performance of the claddings. A good metallurgical bonding between Ni60A claddings and substrate was shown by microstructure. The results of the polarization curves turned out that the corrosion resistance of the Ni60A cladding is apparently better than the matrix.
Effect of Various Side Grooves on 3D Crack-Front J-Integral for CT Specimens
Authors: Li Xiang Qing , Wu Chuan Xiao , Mao Jian Feng , Bao Shi Yi , Gao Zeng Liang
Published: October 2016

Three-dimensional (3D) elastic-plastic finite element model (FEM) is adopted to research the effect of side groove on the crack-front J-integral for different size of Compact Tension (CT) specimens. Although the side-grooved CT specimen is widely used in the existing test method, such as ASTM E1820-13, the test data of fracture toughness is varying with the various geometric parameters. Before FE calculation, the material properties of Q345 steel were obtained by uniaxial tensile test, especially for the true stress-strain relationship. In this paper, it focuses on the numerical study of geometric parameter effects on the fracture toughness. Toward this end, the commercial FE software of ABAQUS is adopted to calculate the J-integral. Since the side groove of CT specimen is so important to make the fracture test success, the various parameters of side groove is intensively analyzed for obtaining the accurate J-integral along the crack front, including the effects of the angle, depth and root radius. In fact, the side groove effect is so significant around the crack front that cannot be ignored in the J-integral calculation. Through rigorous FE investigation, the influence of the side groove on the fracture toughness testing is fully disclosed, and the appropriate side groove configuration is recommended accordingly.
Performance Monitoring Analysis of Liquid Ring Vacuum Pumps
Authors: Qiu Guang Qi , Huang Si , Zhu Lan Lan , Chen Yu , He Jing
Published: October 2016

Liquid ring vacuum pump which uses rotating liquid as piston to abstract and compress gas is a kind of rotating positive displacement pump. Its running state implies some fault informantion. To capture performance levels of liquid ring vacuum pump, a comprehensive performance monitoring system includes data acquisition, data reprocessing, data storage, abnormal judgment and fault alarm, performance displaying is developed in this paper. Hence, the performance levels of liquid ring vacuum pump can be observed anytime by the monitoring system, the maintenance cost can be reduced, pumps can be operated at the highest performance level as far as possible, the reliability and the maintainability of liquid ring vacuum pump can be effectively improved by this monitoring system.
Failure Analysis of the Gray Cast Iron Drain Valve of the Converter Gas Pipe
Authors: Zhang Guo Xin , Niu Jun Nan , Zhang Tai Rui , Liu Yan , Wang Wei Qiang
Published: October 2016

The valve cover of a gray cast iron drain valve, used by a chemical company, cracked during its operation. The cracking reasons of the valve cover were investigated by fracture appearance observation of the valve cover, metallographic observation, SEM observation, chemical composition analysis of the corrosion products, finite element analysis of the valve cover by ABAQUS and tensile tests and impact tests of the cover sample at normal temperature and-12°C. After these investigation jobs, it can be concluded that there was no any significant cast defect or original defect in the fracture of the valve cover, the stress was much lower than the strength of valve cover material, and the cracking of the valve cover was caused by the expansion of the ice which was changed from the seeper between the valve cover and valve body when the weather temperature was lower than-12°C. At the end of this article, some proposals were put forward to the company in order to avoid similar accidents.
Effect of Surface Strengthening on Corrosion Property of Ti-6Al-4V in 3.5% NaCl
Authors: Zhang Cong Hui , Song Wei , Wang Yao Mian , Xiao Gui Zhi
Published: October 2016

By means of Ultrasonic shot peening (USSP), a strengthening surface layer was formed on Ti-6Al-4V. The polarization curves with different treatment times were investigated in 3.5% NaCl. The type of semiconductor for passivation film of 30 min treatment was measured by Mott-Schottky curve, and the thickness of the passivation film was calculated.The result of the polarization curves show that the corrosion resistance of the USSP treatment samples is increased by comparing with the untreated sample. Mott-Schottky curve of 30 min USSP treatment sample show that the passive film belongs to n-type semiconductor. The thickness of the passive film is much thicker than the untreated sample. The charge carrier density is smaller than that of untreated sample. These indicate that the surface strengthening improves the corrosion resistance of the Ti-6Al-4V in 3.5% NaCl by forming stable passive film.
Reliability Assessment of Gas Pipelines with Corrosion Defects Based on In-Line Inspection
Authors: Li Ming Fei , Chen Jian , Lei Zheng Qiang , Zheng Hong Long
Published: October 2016

As the natural gas pipeline system in China is extremely complex and busy, people are coming to realize that existing system safety evaluation methods, which are premised on single pipelines or small-scale pipeline networks, are in fact not technical and rational enough for assessing the safety of a large-scale pipeline network. Therefore, ideas for ensuring the reliability of a large-scale natural gas pipeline network have recently been proposed. To calculate system reliability, the primary task is assessing the reliability of individual system components, such as pipelines and gas stations. This paper advances a reliability calculation model based on the Monte Carlo simulation for pipelines with corrosion def ects determined through in-line inspection. An example of the calculation method is provided; in this example, the reliability of a particular PetroChina natural gas pipeline project is ascertained in order to offer some experiences and references for pipeline reliability assessors.
QDs-Epoxy Resin for Strain Monitoring
Authors: Zhong Qi Xin , Yin Shao Feng , Zhao Zi Ming , Luan Wei Ling
Published: October 2016

The discovery of the variation of the photoluminescence (PL) intensity of quantum dots (QDs) with mechanical deformation has stimulated the interest of developing QDs-based structures for the measurement and monitoring of stress or strain. In this work, tensile bars with the coating of QDs-epoxy composite are subjected to cyclic loading and unloading tests, and the PL intensity of the coating of QDs-epoxy composite is measured as a function of mechanical strain. There are four types of responses in the PL intensity, depending on the loading condition. Transmission electron microcopy is used to examine the rearrangement of QDs in the coatings before and after the tensile tests for understanding the change in the PL response.
Finite Element Analysis and Research on Corrosion Defect of Tank Floor
Authors: Yang Zhi Jun , Chen De Shu , Chen Liang , Liu Yu Zhuo , An Ran , Wang Gang
Published: October 2016

Storage tank is an essential vessel in petrochemical industry, and the corrosion of tank is an important reason for the safety hazard. The corrosion of tank bottom plate is more serious than the tank wall, and it is not easy to check and repair, when damaged to a certain extent it will cause the leakage of the media, then lead to waste of energy, environmental pollution, at the same time it will cause a major accident. Magnetic flux leakage testing is widely used in the field of tank floor inspection with the advantages of fast scanning speed, accurate results and so on. In this paper, the finite element simulation and analysis of the corrosion defect leakage magnetic field is used to obtain the data, and the characteristic of the leakage magnetic field is extracted. The effect of defect depth and width and shape on the magnetic flux leakage field is studied, and the distribution curve of the magnetic flux leakage field is obtained.
Simulation of Alloy Content Assessment in Fe-Si Alloy Steel by Eddy Current Testing
Authors: Zhou Hai Ting , Pan Hong Liang , Chen Jian Jun , Wang Qing Ming
Published: October 2016

The present study, which is based on the finite element method, investigates the alloy element content assessment of these Fe-Si alloy steel sheets from the view point of eddy current testing. The relative permeability and conductivity were preset parameters. Eddy current signals were gathered by a differential type cylindrical probe and subsequent nondestructive tests were carried out with the preparation of four Fe-Si alloy steel sheets with different silicon contents. The result of the numerical simulation demonstrated that the signal increased with the increase of the silicon content in the Si-Fe alloy steel sheets. And the measured result confirmed the rationality of the application of eddy current testing in the average silicon content assessment.
Fitness for Purpose Assessment of Girth Weld Defect Based on In-Line Inspection
Authors: Chen Jian , Lei Zheng Qiang , Wang Fu Xiang , Wang Ting , Li Ming Fei
Published: October 2016

The girth weld defect is one of the most common types of defects on oil and gas pipelines, which can have a strong impact on the operation safety. Several girth weld failure accidents have occurred on PetroChina’s pipelines in recent years. In this paper, PetroChina’s current work on inspection and fitness for purpose assessment of girth weld defects is summarized. The in-line inspection has been proved to be the best practice for oil and gas pipeline defect inspection, but there are still some technical issues such as defect characterization and parameter selection. Fitness for purpose assessment methods for girth weld defects include strength assessment method based on plastic collapse, FAD method based on both plastic collapse and fracture, simplified factor method and numerical analysis method based on finite element. It is critical to identify the actual type of defects detected in in-line inspection to select an appropriate assessment method. The identification of various loads and the selection of appropriate material parameters are also important issues in assessment procedure. The key techniques to be developed include defect characterization, load identification, assessment of defects on high grade steel pipes, reliability-based assessment, etc.
Multiaxial Fatigue of 6061-T6 Aluminum Alloy under Corrosive Environment
Authors: Chen Xu , Xing Rui Si , Liu Xiao Peng
Published: October 2016

Aluminium alloys are widely used in the fields of automobile, machinery and naval construction. To investigate the effect of non-proportional loadings and corrosive environment on the fatigue resistance of 6061-T6 aluminum alloy, a set of uniaxial and multiaxial low cycle fatigue tests were carried out. Firstly, the results of uniaxial tests showed that the alloy exhibited cyclic hardening then cyclic softening. With the increase of stress amplitude the cyclic softening became pronounced. The increasing of plastic deformation was basically cyclically stable with small plastic strain amplitude accumulation when the stress amplitude was lower than 200MPa ,while it was increasing rapidly when the stress amplitude was higher than 220MPa. Secondly, it was observed that non-proportional cycle additional hardening of 6061-T6 aluminum alloy was little. While the fatigue life was badly affected by the loading paths. Thirdly ,the fatigue corrosion interactions were also talked about in details by performing the tests under the same loading conditions with corrosive environment. The experiment proved that the seawater corrosion has huge impact on fatigue life under pH 3. Finally, a multi-axial fatigue life prediction model was used to predict the fatigue life with or without the corrosive environment which showed a good agreement with experimental data.
The Combination of Probabilistic Method and Fracture Mechanics Model in Multiple Cracks Analysis
Authors: Mao Ke Yi , Yang Ya Ning , Feng Zhen Yu
Published: October 2016

Probabilistic method and fracture mechanics model were combined to analysis the failure probability of structure with multiple site cracks. Comparing the result with probabilistic model showed that, accounting the actual failure mode and the interaction of cracks, combination of probabilistic method and fracture mechanics model get better approaching to determine failure probability during structural integrity analysis.
Investigation of Performance and Emission Characteristics of VCR Engine by Using Ceramic Coating on the Piston Crown with Using Methanol Fuel
Authors: Thirunavukkarasu R. , Vadivel A. , Prakash R.
Published: October 2016

The world faces the energy demand, exaggerated crude rates and reduce of fuel resources. Methanol has been considered as an alternate fuel. . The current study takes out an experiment of using methanol in VCR engine. They are blended with diesel at various mixing ratios. The results of methyl alcohol works in engine were checked in an exceedingly single cylinder, direct injection, water cooled and high speed VCR internal combustion engine at varied engine load with constant engine speed of 1500rpm conjointly we tend to mistreatment the limit coated piston with MgO-ZrO2 and Al2O3-13%TiO2 to investigation on performance and emission characteristics. The limit coating materials has low thermal conduction, low thermal expansion and high young’s modules. The influences of blends on CO, CO2, HC, NOX were investigated by emission tests. The brake thermal efficiency of mix M20 was found on top of diesel. The emissions of smoke, hydro carbon and chemical element oxides of methyl alcohol blends were on top of that of diesel. However the CO2 emission is higher once we compare with diesel.