bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibration Influence of Artillery Autoloader Analysis and Testing
Authors: Xing Jie , Duo Yin Xian
Published: June 2013

The inconsistency of the projectile's seizing-bore stroke of the large caliber gun during feeding process will lead to differences of the volume of propellant chamber and starting pressure of projectiles.It will also affect guns' muzzle velocity and firing accuracy.In order to improve the positioning accuracy of projectiles in an arm-type autoloader,first of all,high speed photography was used and only to find that there will be vibrations of projectiles in the direction of gravity.The vibrations will consume kinetic energy of the projectile and contribute to inconsistency of the retaining force.By means of analyzing the working mechanism of the rammer,the motion relationship among the parts during ramming process came to clear eventually.Then the position of the exciting source which causes vibrations of the projectile can be determined by analyzing the force situation of the rammer in the stationary state and the state of motion,and next,testing the amplitude and frequency of the position using laser displacement sensor.Finally,the improved scheme was raised to eliminate the impact of the vibration on stability of ramming.
Execution Process Monitoring for Ship Curved Block Construction Based on Task Package and Workload Distribution Sheet
Authors: Pei Da Ming , Wang Li Rui , Tang Qi Jin
Published: June 2013

Aiming at the demands of top-down task transmission and bottom-up status coordination in the execution of ship curved block construction, a hierarchical execution process monitoring technique considering workplace, curved block, task package (TP) and workload distribution sheet (WDS) was put forward. Adopting linear fitting and graphics epitaxy, the plane vector projection modeling for ship curved block was achieved. Based on visualized monitoring technology for curved blocks evolution over time in workplace, a hierarchical execution process monitoring system was built. Through data collection and feedback based on work distribution sheet, the backwards status coordination was implemented. At last, the validity of the proposed technique was verified by an application example.
Automobile Virtual Display System Design Method Based on Web
Authors: Liu Fei , Lin Nan
Published: June 2013

Car of virtual display, for the enterprise can save large amount of advertising investment, to provide an understanding of product experience. The paper analyzes the common automobile virtual display technology and design method, put forward web environment dynamic interactive 3D browsing solutions, as well as the automobile display system design frame and ideas. With practical examples, to discuss the automobile virtual display design schemes in the process of evaluation and the problem that should be noticed, summarizes the development and application in the future.
Three-Dimensional Modeling of Virtual City: Taking MultiGenCreator for Example
Authors: Liu Pu , Peng Zheng Hong
Published: June 2013

The three-dimensional modeling of virtual city is one of the most basic and most important work in the simulation system of virtual city. This paper mainly summarizes the basic content and the key technologies of the three-dimensional modeling of virtual city, sets forth the modeling steps and methods based on MultiGenCreator and finally gives a brief summary of the application of this technology in urban planning and construction and geographic information system.
A Computer Aided System to Discriminate Enhanced Colon Images by Three Data Mining Methods
Authors: Yu Ya Wen , Lin Hong Mau , Cheng Bor Wen
Published: June 2013

Computer-aided diagnosis for colon polyps automatically determines the locations of suspicious polyps and masses in Colonoscopy and presents them to doctors, typically as a second opinion. The proposed of Computer-aided diagnosis system consists:Using histogram equalization to do the image in the feature extraction and the classification. The researched image data were collected from a community hospital in Mid-Taiwan. First we used the histogram equalization to do the image enhancement, we got six characteristic values and calculate by the gray-scale co-occurrence matrix to get feature extraction. Finally, we used Decision Tree, Logistic Regression and ENSEMBLE to undergo colonoscopy image data classification. This researched found that difference of six texture parameter between normal and polyp group is significant. The accuracy of ENSEMBLE classification is best (90.00%). It indicates the ENSEMBLE classifier based on texture is effective for classifying polyp from tissue on colon imaging. The results of this study can be help the physician to get reliable and consistent diagnostic results and improve the quality of diagnostic imaging.
Human Identification Using One Lead ECG Signal
Authors: Xu Cheng Zhe , Jin Yong Gao
Published: June 2013

This paper presents a new method for human identification using one lead ECG signal. First, preprocessing technique is used to perform the denoising. Then, QRS detection, modified HOAC, and DCT are utilized to extract features from preprocessed data. Finally, 1-nn classifier is used to classify the extracted features. The experimental result based on the proposed method shows the good performance in human identification.
Research on the Cost Sharing of Customer Collaborative Product Innovation
Authors: Zhang Xue , Chen Guang
Published: June 2013

Customer collaborative product innovation is the major style of the innovation activities of enterprises, which not only needs supporting by the hardware and software environment, but the participations of both customers and staffs of enterprises. This paper analyzes the participators in customer collaborative product innovation system form the viewpoints of customers and enterprises respectively. Based on Cooperative game theory, the cost sharing model for customer collaborative product innovation is established. Practical application study is provided for the model use, which analyzes the costs sharing of each participator quantitatively so as to guarantee a long-lasting and stable development for customer collaborative product innovation system.
An Investigation Report Ondigital Manufacturing of Orthoses
Authors: Liu Jian Hui , Wang Yan , Wang Zhi Jian , Li Guo Ping
Published: June 2013

Orthosesare important tools to help patients in rehabilitation andas well asfor theirself-care of disables in clinics. Traditionally, orthese are made manually, which is time consuming and error prone. Digital manufacturing of orthosescan significantly improve the efficiency and reduce lead time compared to tranditionalmethods.This paper attempts to conduct a review on theorthoses manufacturing method based on digital technology including Computer Aided Design (CAD), Comupter Aided Manufacture (CAM) and Reverse Engineering (RE) by examining state-of-the-art academic and industrial reserch.In this paper, the rationale behindthe development of orthoses manufacturing methodsbased on digital technologies isaddressed firstly, followed by adescription ofthecharateristicsofideal orthoses manufacturing methods. Next, some selectedresearchesindigitalorthoses manufacturing in terms of patents and academic papers isreviewedand evaluated against criteria foridealorthese manufacture. Finally thetrend of digital manufacture of ortheseisdiscussed and summarized.
Research on Bottleneck of Emergency Logistics Capability Based on Emergency Logistics Network
Authors: Wang Tian Yong , Gao Ge , Wang Yu Lei , Wang Qian Qian
Published: June 2013

Based on the emergency logistics network, the research calculate the logistics capability of each node and the line in the network .Then the research find out the bottlenecks link in emergency logistics network according to theory of constraints .At last, the research improve the capability of bottleneck link to improve the ability of the whole emergency logistics network rapidly.
A New Response Surface Method for Structural Reliability Analysis
Authors: Li Guang Bo , Meng Guang Wei , Li Feng , Zhou Li Ming
Published: June 2013

The response surface method is adopted to analyze the structural reliability. This paper presents a new response surface method with the uniform design method to predict the failure probability of structures. It is the response surface method based on Fourier orthogonal basis function (RSM-Fourier). To reduce computational costs in structural reliability analysis, approximate Fourier response surface functions for reliability assessment have been suggested. The method involves the selection of training datasets for establishing a model by the uniform design points, the approximation of the limit state function by the trained model and the estimation of the failure probability using first-order reliability method (FORM). The proposed method is applied to examples, compared with other methods to demonstrate its effectiveness.
Faults Diagnosis of Converter Transformer Based on the Vibration Method
Authors: Cui Hong
Published: June 2013

The vibration of windings and iron core causes the overall vibration of the transformer. Significant changes of transformer vibration condition will take place when the windings or core has fault, so the vibration method can be used to diagnose the transformer's potential fault. The characteristics and transmission route of the transformers' vibration were analyzed. The vibration of a certain transformer in converter station was picked up, using vibration measuring system. The test results aree analyzed comparatively and maintenance suggestion was proposed.
Forward and Inverse Kinematic of Continuum Robot for Search and Rescue
Authors: Meng Guang Zhu , Yuan Guang Ming , Liu Zhe , Zhang Jun
Published: June 2013

Continuum robot is a new type robot which has many applications,such as medical surgery, mine collapse, urban search and rescue etc. In this paper, the forward and inverse kinematics analysis of continuum robot for search and rescue is presented. The forword kinematic has been formulated by product of exponentials. The inverse kinematics for the robot is carried out by a geometrical approach. Finally, the forward and inverse kinematic simulation is completed by Matlab. The simulation results are given for the robot to illustrate the method effectiveness.
A User-Based Modeling and Analysis of Network Public Opinion Using Particle Swarm Optimization
Authors: Kan Ding Yue , Ma Rui Xin
Published: June 2013

In the current researches on network public opinion, the events are mostly focused, instead of the users who are of great significance, but often ignored. Concerning this problem,the user-based event model encompassing the users and their concepts is introduced in this paper, and user concept clustering in spreading events is simulated with the speciation algorithm based particle swarm optimization (SPSO). According to the results of user concept clustering, the analysis of event dynamic evolution model is implemented. The clustering convergence velocity of users is controlled with the change of velocity parameter for subsequently coordinating event evolution, so that the recognition of network hot events is realized and the situation of emergencies is analyzed.Finally, the PSO-based and SPSO-based clustering behaviors of users are simulated, respectively. The experimental results show that SPSO can more effectively simulate the clustering behaviors of users in public opinion network and discover multiple user clustering centers.
EEG-Based Music Mood Analysis and Applications
Authors: Xu Xin , Guan Hui , Liu Zhen , Wang Bo Jun
Published: June 2013

Music is known to be a powerful elicitor of emotions. Music with different moods induces various emotions, each of which corresponding to certain pattern of EEG signals. In this paper, based on current music mood categories, we discuss how the music belonging to different mood types affect the pattern EEG activity. We review several literatures verifying that certain characteristics of EEG differ from each other induced by different types of music. Such differences make it possible for emotion recognition through EEG signals. We also introduce some applications of emotional music such as improvement of human emotions and adjuvant treatment of diseases.
Psychoacoustic Properties Analysis on Interior Noise of High-Speed Trains
Authors: Yang Li Fang , Meng Fan Yu , Kang Bo
Published: June 2013

In order to analyze the noise properties and promote the sound comfort of the high-speed train, the noise samples are collected in passengers cars, dining cars and car joint parts at different speeds. By means of 18 sound samples, the psychoacoustic parameters of the high-speed train are discussed. Before calculation of other psychoacoustic properties, the calculation method of loudness must be properly chosen through analysis of all loudness calculation method. In the paper, the Filter/ISO 532B method is selected to obtain the loudness of the high-speed train and based on the loudness; other psychoacoustic properties are obtained and analyzed. The discussion of psychoacoustic properties is the basis of further noise evaluation and control of high-speed trains.
Modularization Analysis Approach of Product Family for DFMC Based on Complex Network
Authors: Fan Bei Bei
Published: June 2013

Customers requirements are mapped into function modules, matching with structure modules and signing the corresponding structure entities. Main structure of product family can be depicted as a directed complex network. Parameters such as node betweenness, edge betweenness and Q function values are calculated through simple-path detecting algorithm, for obtaining distributing curve of Q and clustering dendrogram which we can gain division results from. The results are adjusted and optimized according to the parts usage times and structure entities with sign. As an example, the product family of industry steam turbine is analyzed with this algorithm and some practical results are obtained.
Plating Hard Chrome Plating Alternative Technologies - HVOF Tungsten Carbide Coating
Authors: Zheng Yi
Published: June 2013

HOVF technology preparation of tungsten carbide coating, can be obtained the microhardness and neutral salt spray corrosion resistance superior to the protective layer of hard chrome plating, its own good toughness and high bonding strength of the matrix, itideal replacement for hard chrome plating technology
Comparison of Methods for the Sulfur Compounds and Elemental Sulfur Analysis in High-Sulfur Natural Gas
Authors: Luo Qin , Tu Zhen Quan , Ji Zhong Li , Xiao Xue Lan , Chang Hong Gang , Xu Wen Xiao
Published: June 2013

Some gas fields with high hydrogen sulfide content, such as Luojiazhai, Dukouhe and Puguang Gas Fields, are found in Northeast Sichuan. For exploring and utilizing high sulfur natural gas reservoirs, it is essential to quantificational analysis of sulfur compounds and elemental sulfur in high sulfur natural gas. Determination of hydrogen sulfide content in natural gas with a laser method has many advantages, including on-site measurement, fast response, wide application scope, high accuracy, high reliability, and low maintenance. When the hydrogen sulfide concentration is 1% to 20%, the relative deviation of the analysis value to the standard value is less than 3% with repeatability of less than 1%. Determination of sulfur compounds in natural gas by gas chromatograph with sulfur chemiluminescence detector (SCD) also has many advantages, such as it is simple, fast, accurate and free from interference of most sample matrixes. The analysis method has good repeatability with lower limit of detection. Since SCD has liner equimolar response to sulfur atom, only one reference gas mixture of sulfur compound is used as external standard calibration. Determination of total sulfur content in natural gas with oxidative microcoulometry method has good repeatability and high accuracy. Determination of elemental sulfur by liquid chromatography has repeatability better than 3%, the detection limit is 10mg/m3, and recovery rate of over 90%, and is applicable for determination of elemental sulfur content in high sulfur natural gas.
Effect of Foaming Temperature and Holding Time on Foam Glass
Authors: Wu Long , Zhao Yi Long , Chen Rong Fa , Yang Hua , Li Qing Qing , Li Zhi Long , Lu Hua Feng
Published: June 2013

In the paper, the effects of the foaming temperature and holding time on the quality of the foam glass were investigated by means of the different foaming technology. The results indicated that lots of the defects, such as the non-uniform size of the bubbles, big hole and the pit at the bottom, were caused by the high foaming temperature. The fine pore structure was formed by the low temperature. The molding and properties of the foaming glass was affected by the length of the heat preservation time. The rate of acceptability and the mechanical property of the foam glass can be effectively improved by the optimized foaming technology.
A Robust Procedure for Damage Detection from Strain Measurements Based on Principal Component Analysis
Authors: Guemes Alfredo , Sierra-Pérez J. , Rodellar J. , Mujica L.
Published: June 2013

FBGs are excellent strain sensors, because of its low size and multiplexing capability. Tens to hundred of sensors may be embedded into a structure, as it has already been demonstrated. Nevertheless, they only afford strain measurements at local points, so unless the damage affects the strain readings in a distinguishable manner, damage will go undetected. This paper show the experimental results obtained on the wing of a UAV, instrumented with 32 FBGs, before and after small damages were introduced. The PCA algorithm was able to distinguish the damage cases, even for small cracks. Principal Component Analysis (PCA) is a technique of multivariable analysis to reduce a complex data set to a lower dimension and reveal some hidden patterns that underlie.
Prediction and Measurement of Lamb Wave from Debondings at Structural Features in Composite Laminates
Authors: Ng Ching Tai , Veidt Martin
Published: June 2013

The interaction of the fundamental anti-symmetric Lamb wave (A0) with debondings at structural features is investigated using experimental data and finite element (FE) simulations. In this study explicit three-dimensional (3D) FE simulations are employed, which allows the study of the scattered wave along different propagation directions. Good agreement between the FE predictions and the measurements are obtained that demonstrates that the 3D FE scattering model is able to accurately predict the Lamb wave scattering characteristics at debondings.
The study show that the characteristics of Lamb wave reflected from the debondings at the structure feature is much more complicated than that from defects in flat composite laminates. Parameter studies show that the backward and forward scattering coefficient of Lamb wave is a function of debonding size to wavelength ratio and debonding location. This shows the potential of employing Lamb wave to identify the size and monitor the growth of the debondings. The findings of the study provide improved physical insights into the scattering phenomena, which are important to further advance damage detection techniques for complex structures made by composite laminates.
Optimal Coil Transducer Geometry for an Electromagnetic Nonlinear Vibration Energy Harvester
Authors: Vandewater Luke A. , Moss Scott D. , Galea Steve C.
Published: June 2013

This paper investigates the optimisation of wire-coil transducers for a recently described strongly nonlinear electromagnetic (EM) vibration energy harvester, by coupling previously derived dynamics of the mechanical system with finite element analysis (FEA) to determine the harvesters EM response. The harvester is implemented in a permanent-magnet/ball-bearing arrangement, where vibrations in a host structure induce oscillations of the ball-bearing. The movement of the bearing changes the magnetic flux in a circular pancake wire-coil, inducing an electromotive force (EMF) in the coil and hence a voltage in the harvester circuit. A quintic-modified Duffing equation is applied to predict frequency-displacement relations for the nonlinear dynamics of the harvester. Faradays Law of Induction is implemented with quasi-static FEA modelling of the magnetic field and linked to the dynamics of the system to develop a numeric model for voltage predictions. The issue of back-EMF and damping is also investigated. A fully integrated mechanical-electromagnetic model is shown to compare well to the quasi-static numerical model. The output characteristics of the prototype harvester are then compared with the numerical model. An optimal coil height of 2 mm is predicted, and demonstrated experimentally to produce 20.3 mW from a 12 Hz, 500 milli-g host vibration. Further investigation of coil inner radius and outer radius yields a predicted resistive load power transfer increase of 18% with the optimal coil geometry.
Modeling of Environmental Effects for Vibration-Based SHM Using Recursive Stochastic Subspace Identification Analysis
Authors: Loh Chin Hsiung , Chen Ming Che
Published: June 2013

This paper deals with the problem of a bridge structure identification using output-only vibration measurements under changing environmental conditions. Two key issues of a real-life monitoring system are addressed through analysis. The first issue is the identification of structural dynamic characteristics directly from measurements under operating conditions. The covariance-driven recursive stochastic subspace identification (RSSI-COV) algorithm is applied to extract the system dynamic characteristics. The second issue is to distinguish the system dynamic features caused by abnormality from those caused by environmental and operational variations, such as temperature, and traffic loading. In this study a solution is proposed to model and remove the uncertainty due to environmental effects from the identified system dynamic characteristics from on-going measurements. Nonlinear principal component analysis incorporated with AANN is employed to distinguish the dynamic feature changes caused by abnormality from those caused by environmental and operational variation (i.e. ambient temperature and traffic loadings). Finally, field experiment of a bridge is conducted. The variation of the identified system natural frequencies was discussed by using the proposed method.
Development and Validation Roadmap for In Situ Structural Health Monitoring of ADF Aircraft
Authors: Galea Steve C. , Rajic Nik
Published: June 2013

In recent times there has been concerted pressure on military organisations worldwide to push for significant reductions in through-life support costs while maintaining and improving aircraft availability and safety. These goals, which on the surface may appear contradictory, can be achieved through the introduction of Structural Health Monitoring (SHM) systems. The paper describes the Australian Defence Science and Technology Organisation (DSTO) roadmap for SHM system development, validation, certification and implementation, in the context of technologies and systems that meet Australian Defence Force (ADF) future requirements. The current approach focuses on wide-area damage detection SHM systems using acousto-ultrasonic techniques.
Applications of Compressive Sensing Technique in Structural Health Monitoring
Authors: Bao Yue Quan , Li Hui , Ou Jin Ping
Published: June 2013

Compressive sampling also called compressive sensing (CS) is a emerging information theory proposed recently. CS provides a new sampling theory to reduce data acquisition, which says that sparse or compressible signals can be exactly reconstructed from highly incomplete random sets of measurements. CS broke through the restrictions of the Shannon theorem on the sampling frequency, which can use fewer sampling resources, higher sampling rate and lower hardware and software complexity to obtain the measurements. Not only for data acquisition, CS also can be used to find the sparse solutions for linear algebraic equation problem. In this paper, the applications of CS for SHM are presented including acceleration data acquisition, lost data recovery for wireless sensor and moving loads distribution identification. The investigation results show that CS has good application potential in SHM.
Strain as Damage Indicator for Truss and Frame Structures
Authors: Opoka Szymon , Murawski Lech , Wandowski Tomasz , Malinowski Pawel , Ostachowicz Wieslaw
Published: June 2013

Damage detection techniques are becoming more and more important issues for prolonging the lifetime of the old structures. In the paper the strain measurements on offshore oil platform leg model as well as the preliminary measurement system installed on jack-up rig is presented. During experiments performed on frame model of the platform leg different types of damage scenarios were tested. The Fiber Bragg Grating (FBG) strain sensors were capable to detect damage. After laboratory experiments, preliminary FBG system was installed on the real construction (jack-up rig) excited by environmental and operation-induced forces. It is evident that strain measurement based on FBG technology is very promising technique for use in truss/frame structures.
Electrochemistry and In Situ EPR Spectroelectrochemistry of Poly(3,4-ethylenedithiothiophene)
Authors: Zassowski Pawel , Domagala Wojciech , Lapkowski Mieczyslaw , Skabara Peter J.
Published: June 2013

Polymer films of poly(3,4-ethylenedithiothiophene) obtained by electrochemical oxidative polymerisation of the corresponding monomer have been investigated. p-Doping process of the polymer was characterized by in situ EPR spectroelectrochemisty. Compared to its close relative – PEDOT, the polymer features two distinct voltammetric peaks. The results of our studies indicate that both represent faradaic processes and that each manifests generation of charge carriers in the polymer.
The Effect of Montmorillonite Type Nanoparticles on Stiffness and Flammability of Rapeseed Oil Based Polyisocyanurate Foams
Authors: Cabulis Ugis , Kirpluks Mikelis , Andersons Janis
Published: June 2013

Polyisocyanurate foams incorporating polyols derived from rapeseed oil are developed, with the polyol system comprising up to 80% of rapeseed oil esters. To enhance the mechanical characteristics and fire resistance of the foams, they are filled with three different types of organically modified clay (organoclay) in the range of loading from 1 to 5% by weight. Marked increase in tensile stiffness of nanocomposite foams is observed.
Level of Comfort: Artificial and Natural Shoe Materials. A Comprehensive Assessment
Authors: Fordzyun Yuriy , Andreyeva Olga , Maistrenko Lesia
Published: June 2013

Hygroscopicity, moisture return, wetting, capillarity and water vapour permeability of materials were studied in shoes linings and insoles made of natural and artificial leather. It was established that liquid-based and final finishing deteriorate hygienic properties of natural leather to a great extend. With the use of obtained results, a new graphically-numerical method was tested in assessment of shoe material comfortability, the materials that have direct contact with the human foot. According to the method, the ratio between pentagon areas of material tested and reference material is taken as quantitative indicator of quality.
PHA Latex Composite Films: Mechanical Properties and Surface Visualization
Authors: Gonta Svetlana , Savenkova L. , Kolosovskis J. , Dzene A. , Tupureina V. , Bulanov Andrejs , Kirilova E.
Published: June 2013

Homopolymer PHB and copolymer PHB/HV containing granules were isolated from Azotobacter chroococcum cells and used for latexes formation. Composite latex films were formed from the PHB and PHB/HV latexes with different content of poly (vinyl alcohol) and glycerol and a hydrophobic fluorescent benzanthrone derivated dye 3-piperidinobenzanthrone, possessed high fluorescence intensity in a system with PHA granules. Fluorescence based methods were used for characterization of the elaborated latex film by their stability at high temperature and for visualization of the film surfaces PHA granules distribution. Film stability in phosphate buffered saline was evaluated by dye migration activity in the solution. The results of mechanical testing of the latex films were compared with the stability testing and surface visualization results. The data obtained allow a better understanding the difference of the mechanical and physical properties of the investigated films.
Influence of Nanoclay Additive on Mechanical Properties of Bio-Based Polyurethane Nanocomposites
Authors: Ivakina K. , Skadins E. , Kiyanitsa A. , Gaidukov S. , Tupureina V. , Cabulis Ugis , Maksimov Robert D.
Published: June 2013

This paper is about investigation of the bio-based polyurethanes from the rapeseed oil polyols and their modification with montmorillonite nanoparticles. The results of hardness and tensile properties investigation of polyurethane / montmorillonite nanocomposites are presented.
Thermal and Mechanical Properties of Unvulcanized Polypropylene Blends with Different Elastomers: Ethylene-Propylene-Diene Terpolymer, Nitrile-Butadiene Copolymer and Chlorinated Polyethylene
Authors: Reinholds Ingars , Kalkis Valdis , Zicans Janis , Merijs Meri Remo , Grigalovica Agnese
Published: June 2013

In this work, composites of isotactic polypropylene (PP) with three unvulcanized elastomers – terpolymer of ethylene-propylene-dicyclopentadiene (EPDM), chlorinated polyethylene (CPE) and copolymer of acrylonitrile-butadiene (NBR) – have been investigated. The purpose of the investigation was to create PP/elastomer blend composites of significantly different compositions (with an excess of PP, intermediate ones, and with an excess of elastomer) and to study the dependence of tensile behaviour and elastic properties on the blends with different component ratio. Tensile properties have been recognized from the stress-strain curves. The changes of elastic modulus have been characterized with respect to the Hashin-Shtrikman upper and lower bounds and the Davies equation. Calorimetric properties of PP blends with elastomers (crystallinity and melting behaviour of polypropylene phase) have also been investigated with the method of differential scanning calorimetry (DSC).
Modeling Residual Stresses in Superduplex Stainless Steel Welded Pipes Using the Finite Element Method
Authors: Rezende Fabiano , de Souza Luís Felipe Guimarães , Calas Lopes Pacheco Pedro Manuel
Published: June 2013

Welding is a complex process where localized and intensive heat is imposed to a piece promoting mechanical and metallurgical changes. Phenomenological aspects of welding process involve couplings among different physical processes and its description is unusually complex. Basically, three couplings are essential: thermal, phase transformation and mechanical phenomena. Welding processes can generate residual stress due to the thermal gradient imposed to the workpiece in association to geometric restrictions. The presence of tensile residual stresses can be especially dangerous to mechanical components submitted to fatigue loadings. The present work regards on study the residual stress in welded superduplex stainless steel pipes using experimental and a numerical analysis. A parametric nonlinear elastoplastic model based on finite element method is used for the evaluation of residual stress in superduplex steel welding. The developed model takes into account the coupling between mechanical and thermal fields and the temperature dependency of the thermomechanical properties. Thermocouples are used to measure the temperature evolution during welding stages. Instrumented hole drilling technique is used for the evaluation of the residual stress after welding process. Experimental data is used to calibrate the numerical model. The methodology is applied to evaluate the behavior of two-pass girth welding (TIG for root pass and SMAW for finishing) in 4 inch diameter seamless tubes of superduplex stainless steel UNS32750. The result shows a good agreement between numerical experimental results. The proposed methodology can be used in complex geometries as a powerful tool to study and adjust welding parameters to minimize the residual stresses on welded mechanical components.
Numerical Simulation of Metal/Cement Push-Out Test
Authors: da Silva Neto José Felix , da Silva Elisângela Pereira , de Farias Walquiria Galdino Mendes , de Albuquerque Arthur Alves , Torres Sandro Marden , de Barros Silvio Romero
Published: June 2013

In petroleum wells, the adhesion between the steel and the cementitious coating material is responsible for ensuring the efficiency of the mechanical point of view and of the thermodynamic stability of steels, protecting them against corrosion, preventing the escape of fluids inside and hydraulically isolating the structure against infiltration. The push-out test is used to measure the level of adhesion between the steel and cement. In this paper, the numerical simulation of steelcement interface was performed to reproduce the mechanical behavior of this interface used a cohesive zone model combined with Coulomb's law for friction. The proposed model was implemented in CAST3M software. The numerical results obtained with the proposed model were compared with experimental results of push-out test. The comparison between the force versus displacement curves, obtained experimentally and numerically, validated the proposed model.
Geopolymerics Adhesives for Joint Steel Plates
Authors: Gomes Kelly Cristiane , de Lira Elder Cunha , de Sousa Andre R.R. , Rosas Marçal , Torrres Sandro Marden , de Barros Silvio Romero
Published: June 2013

The process of bonding degradation throughout the whole loading phase up to the total collapse has been investigated by models of interlaminar degradation in composite materials and subsequently adapted to the problem of structural bonding. The physical phenomenon represented by these models is exactly the same that must be studied in the case of metal plates adhered with geopolymers: the adhesion between substrates. In this work, it was investigated the adherence of joint steel plates through propagation tests of clefts in mixed mode MMF (Mixed-Mode Flexure Test) which combine the efforts of traction (due to differential thermal expansion) and shear (due the slipping and preassure due the own weight of the adhered layers), in other words, modes I (pure opening) and II (pure shear) of propagation, being one of the most common glued plates. It was used two types of geopolymeric adhesives (one made of metakaolinite and another with weathered soil) activated with sodium silicate. The bonded systems were subjected to temperatures between 55°C and 600°C in order to evaluate its potential against the use of epoxy-based adhesives. The substrates used were steel. In general, the adhesives made of metakaolinite had better adhesion.
Effect of the Cutting Velocity and Heat Treatment on Turning Cutting Forces of an SMA Cu-Al-Be Alloys
Authors: Pereira da Silva Francisco Valdenor , Vogel José Paulo , Gomes Rodinei Medeiros , Melo Tadeu Antonio de Azevedo , Araujo Anna Carla , de Barros Silvio Romero
Published: June 2013

This work studies the effect of heat treatment and cutting velocities on machining cutting forces in turning of a Cu-11.8%Al-0.55%Be shape memory alloys. The heat treatment was performed to obtain samples with austenite and martensite microstructures. Cutting force was investigated using a 3-component dynamometer in several revolutions and data were analyzed using statistic tools. It was found that the resultant forces were higher in quenched alloy due to the presence of Shape Memory Effect. Chip formation occurred in a shorter time in the sample without the Shape Memory Effect.
Cobalt-Base Superalloy Coating Using GTAW Process
Authors: de Souza Royse Fernanda de Souza , Bastos Ivan Napoleão , Costa Hector Reynaldo Meneses
Published: June 2013

In harsh operational conditions, the low-alloy steels need to be protected from the environment. Thus, against corrosion and wear, an ordinary choice is metallic cladding. In this sense, the present study aimed to evaluate the properties of cobalt base superalloy coating deposited by gas tungsten welding process (GTAW) on steel SAE 4140. A circumferential weld was chosen due to its critical restraint. Four coating conditions were studied varying the welding currents. A microstructural evaluation was done using optical and scanning electron microscopy. The physical properties of coatings were additionally evaluated by microhardness measurement and dilution quantiﬁcation. The results obtained indicated, for all conditions, a uniformity of layers. However, the deposited weld characteristics are strongly dependent on welding parameters. For the welding parameters studied, the maximum dilution of 60.8% was observed in coatings with austenitic and dendrite microstructures welded with 110 A current. Moreover, the metallographic analysis and microhardness tests showed, for some cases, the presence of partially diluted zone, a microstructural layer in the transition region of base metal and coating. The welding performed with current of 90 A showed the best combination of microhardness and dilution aspects, without defects in coating.
Development of a Methodology to Determine Thickness Measurement Uncertainties by Ultrasonic Test in Aerospace Parts
Authors: de Andrade Silva Bruno César , Motta Mauricio Saldanha , de Oliveira José Eduardo Ferreira
Published: June 2013

In the aerospace industry, each year several commercial airplanes stop its service to carry out detailed routine inspections of their structural members and systems, including the power plant. Among several maintenance services to be performed in an airplane during a check, the corrosion prevention and control program is the one of the most important service since it includes methods of inspection and tasks to prevent corrosion in all airplane structural areas, such as fuselage, wings, stabilizers, flight control surfaces etc. During routine inspections, upon discrepancy detection, some actions must be immediately taken in order to correct the problem and avoid the loss of airplane structural strength. The corrosion removal from any aircraft structural member, in general consists in blending out the damage and carry out a visual and ND inspection (e.g. remaining thickness measurement by ultrasonic test). However, all care must be taken during remaining thickness measurement since systematic and random errors can affect in the results, compromising the final quality of measured parts. The main purpose of this paper is to perform an experimental study of remaining thickness measurement in an aircraft outer wing skin after corrosion removal, objecting to determine the uncertainty sources of the usual method. Also, the study intends to determine the expanded uncertainty in order to purpose a new methodology for the metrological treatment of this process, establishing a conformity zone.
Evolution and Prediction of Texture in Commercially Pure Warm Rolled Titanium
Authors: Raptopoulos Luciano Santos Constantin , Castello-Branco Gilberto Alexandre , Bacaltchuk Cristiane Maria Basto , Dragomir-Cernatescu Iuliana , Garmestani Hamid
Published: June 2013

Titanium alloys are used in a wide variety of aerospace, energy, industrial and biomedical applications, among other reasons, due to their superior properties. These properties are highly dependent of materials microstructure, i.e. texture, dislocation density and slip system activity. Therefore, in order to be able to design materials with certain properties it is crucial an understanding of the deformation process in terms of microstructural parameters. Microstructure evolution in warm rolled commercially pure titanium was investigated by means of X-ray diffraction and modeled with a crystal plasticity self-consistent scheme. Texture measurements and peak profile analysis were used to characterize the deformation texture and evaluate the relative activity of the various slips systems activated during the deformation process. The peak profile analysis data and the self-consistent predictions of texture evolution showed a good agreement with the experimental deformation texture evolution.
Colectomy for Porto-Systemic Encephalopathy: Is It Still Topical?
Authors: Ennaifer Rym , Hayfa Romdhane , Hefaiedh Rania , Marsaoui Lobna , Bel Hadj Najet , Khalfallah Tahar
Published: June 2013

Hepatic encephalopathy (HE) is a common long term complication of porto-systemic shunt. We report herein the case of a 59-year-old man with Child-Pugh A cirrhosis treated successfully 9 years earlier with distal splenorenal shunt for uncontrolled variceal bleeding. In the last year, he developed a severe and persistent hepatic encephalopathy secondary to the shunt, which was resistant to medical therapy. As liver transplantation was not available and obliteration of the shunt was hazardous, we performed subtotal colectomy in order to reduce ammonia production. This therapeutic option proved successful, as the grade of encephalopathy decreased and the patient improved. Our experience indicates that colonic exclusion should be considered as an option in the management of HE refractory to medical treatment in highly selected patients when liver transplantation is not available or even as a bridge given the long waiting time on lists.
Short-term threats for the sustained survival of freshwater Mollusca in the Olifants River and selected tributaries.
Authors: De Kock Kenné N. , Wolmarans Cornelius T. , Kemp Mathilde , Roets Wietsche
Published: June 2013

The conservation status of less than 2% of the more or less 7000 mollusk species known worldwide have been properly assessed. Consequently the general level of imperilment is poorly documented and almost certainly underestimated. Freshwater mollusks live permanently in water, have limited means of movement and are exposed to a variety of anthropogenic waste products due to the fact that waterbodies often act as sinks for a large array of harmful pollutants. The Olifants River is often described as one of the most polluted rivers in Southern Africa and is progressively subjected to extremely high pressure with regard to natural resources and associated rural transformation and pollution. Little is on record regarding the diversity of the Mollusca in the Olifants River; therefore, in the present study, four surveys of the molluscs were conducted in this river and selected tributaries during two consecutive years at three localities situated on the Highveld and four localities situated in the Lowveld respectively. The pH and electric conductivity of the water were determined during each survey at each one of the localities and values ranged from 6.93 to 9.50, and 110 µS to 1336 µS, for pH and conductivity respectively. A total of 25 mollusk species were collected during the four surveys which included the exotic invader species Lymnaea columella, Physa acuta, Aplexa marmorata and Tarebia granifera. The latter species yielded the highest number of specimens by far, mainly at a locality which could be described as largely transformed. The results of this investigation can serve as a point of departure for future surveys to evaluate the impact of anthropogenic disturbances on the mollusc diversity in the Olifants River and catchment.
Scoring multiple choice questions
Authors: Barnard John J.
Published: June 2013

This article briefly touches on how different measurement theories can be used to score responses on multiple choice questions (MCQs). How missing data is treated may have a profound effect on a person’s score and is dealt with most elegantly in modern theories. The issue of guessing a correct answer has been a topic of discussion for many years. It is asserted that test takers almost never have no knowledge whatsoever of the content in an appropriate test and therefore tend to make educated guesses rather than random guesses. Problems related to the classical correction for guessing is highlighted and the Rasch approach to use fit statistics to identify possible guessing, is briefly discussed. The threeparameter ‘logistic’ item response theory (IRT) model includes a ‘guessing item parameter’ to indicate the chances that a test taker guessed the correct answer to an item. However, it is pointed out that it is a person that guesses, not an item, and therefore a guessing parameter should be a person parameter. Option probability theory (OPT) purports to overcome this problem through requiring an indication of the degree of certainty the test taker has that a particular option is the correct one. Realistic allocations of these probabilities indicate the degree of guessing and hence more precise measures of ability.
Purslane (Portulaca oleracea L.) has potential for desalinizing greenhouse recirculation water
Authors: Ngosong Christopher , Halpern Moshe T. , Whalen Joann K. , Smith Donald L.
Published: June 2013

Ngosong, C., Halpern, M. T., Whalen, J. K. and Smith, D. L. 2013. Purslane ( Portulaca oleracea L.) has potential for desalinizing greenhouse recirculation water. Can. J. Plant Sci. 93: 961–964. Recirculating fertigation solutions improves the environmental sustainability of hydroponics-based vegetable production in Canada. Purslane is an edible halophyte with proported medicinal benefits that could absorb excess salts from recirculation water. It grew well in hydroponic solutions with up to 1000 mg NaCl L−1. Greatest Na absorption occurred during earlier vegetative growth.
The profitability of short-duration canola and pea rotations in western Canada
Authors: Smith E. G. , Kutcher H. R. , Brandt S. A. , Ulrich D. , Malhi S. S. , Johnston A. M.
Published: June 2013

Smith, E. G., Kutcher, H. R., Brandt, S. A., Ulrich, D., Malhi, S. S. and Johnston, A. M. 2013. The profitability of short-duration canola and pea rotations in western Canada. Can. J. Plant Sci. 93: 933–940. A long-term field study of canola and pea interval in rotations was used to determine the most profitable canola production systems. The duration between canola crops has been declining with most canola grown more often than the recommended once every 4 yr. Producers could be reducing their long-term profitability if the short-duration canola rotation results in increased disease and lower yield. A field study was conducted from 1998 to 2007 at Scott and from 1999 to 2006 at Melfort in Saskatchewan, Canada, to examine the long-term impact of shorter-duration canola and pea rotations. Canola and pea were grown continuously, or in rotations with wheat or flax for 2, 3, or 4 yr. Two canola types were used, one was a blackleg-susceptible conventional cultivar and the other a blackleg-resistant hybrid. The returns above variable costs for the production systems were determined over the last 4 yr of the study, the period of time when rotation impacts should be most evident in this study. The continuous canola and pea rotations were the least profitable rotations. Blackleg-susceptible canola had higher return when in rotations of 3 or 4 yr, compared with continuous or 2 yr. Blackleg-resistant hybrid canola had statistically similar returns for 2, 3 and 4-yr rotations, which were superior to continuous canola. Even with increased blackleg disease incidence and severity after several years of a short-duration canola rotation, the short-duration canola rotation was more profitable when growing the disease-resistant hybrid. With high canola prices, the returns from the short-duration canola rotations were as high, or higher, than rotations with more years between canola crops. The canola industry must recognize that producers have an economic incentive to use short-duration canola rotations and new systems (disease resistance and rotations) need to be developed within this context.