bluuebunny/crossref_metadata_2025 huggingface dataset:
Study and Calculation of Geomagnetic Induced Current in Power Grid
Authors: Zhang Li Ying , Wang Ze Zhong
Published: May 2014

With the development of long distance power transmission in China, Jiangsu, Guangdong and many other places have seen significantly geomagnetic induced current (GIC) in power grid . GIC could bring about great harm to power grid. To study the effect of GIC on power grid, the calculation of the GIC should be done firstly. In this paper, several kinds of GIC calculation model are summarized and analyzed, their advantages and disadvantages are pointed out, And further discusses the finite element algorithm of GIC. Shortcomings of the present situation of GIC calculation are analyzed, and the research direction suitable for the actual situation f is proposed.
A Complaint Mechanism with Freedom Degrees of One Movement and Two Rotations
Authors: Lin Sheng , Kong Xi , Wang Chun
Published: May 2014

Based on the method of Freedom and Constraint Topology (FACT), a compliant mechanism with 3 degrees of freedom is designed. The 3 DOF are one movement and two rotations, which belongs to Case 3, Type 2. The whole stiffness matrix of the compliant mechanism is obtained. The finite element model is established for statics analysis. The results of theory analysis and finite element method are closed.
Microcavity Connceted with a Waveguide for Application to Optical Sensing
Authors: Liu Shuai , Chen Zhi Wei , Gu Zhi Yuan , Zhai Hui Lin , Song Qing Hai
Published: May 2014

A high-performance microcavity sensor with a port connected with a waveguide directly is investigated numerically. With input light and output light transmitting in the same waveguide, we propose a robust coupling mechanism. For a circular microcavity with a diameter of 20μm and a refractive index of 1.45, our numerical results show that the coupled modes are excited and more than 5×104 Q-factor is calculated from the transmission spectrum. Dramatically, the spectrum shows a fano-shape resonance at specific wavelength which is useful for high-precision optical sensing on the order of 10-5.
Discussion on Calculation Method of Internal Force of Bending Beam in Mechanics of Materials
Authors: Xia Yan
Published: May 2014

When analyzing the inner bending force and drawing the inner force,students often have confusion and make mistakes on the positive and negative values of the inner force.Based on the method of the symbols prescribed by the relevant teaching materials,I summed up a set of method easy to understand.Combining the living examples,this paper elaborated the simple regulation of the positive and negative rules of the internal force and calculation methods on the basis of method of sections.
A FLL-PLL Cooperative GNSS Weak Signal Tracking Framework
Authors: Liu Yang , Zhu Yan Bo
Published: May 2014

Navigation signals should be steadily tracked to allow the extraction of navigation information, and support the calculation of navigation solution. Generally, extraction of navigation information is realized by GNSS tracking loops, which need to implement two critical operations: 1) tracking parameters should be precisely estimated in order to reliably decode the navigation message. 2) Successive tracking method of navigation information. This paper proposes a novel tracking framework using dynamic FLL assisting PLL strategy and a loop state detection monitor. The new framework extends traditional phase and delay locked loop (PLL/DLL) tracking framework, and contributions mainly lie in two parts. A dynamic framework for parameters adjustment is proposed to avoid tracking failure due to the change of environment, which is complemented in a FLL-PLL cooperative framework. Experimental results demonstrate the advantages of our algorithm compared with standard PLL/DLL framework. It is shown that the algorithm proposed is more suitable for tracking under signal attenuation situation, while maintaining high performance at the same time.
Modeling and Simulating of PMSM Space Vector PWM Drive System Based on Fuzzy Immune PI Control Method
Authors: Jiang Nan , Fan Jian Wen , Tan Guang Xing
Published: May 2014

In order to improve the speed control performance of the PMSM(Permanent magnet synchronous motor) vector control system. Utilizing the mathematical model of the PMSM in the dq0 coordinates, and the basic principles of the SVPWM (Space Vector Pulse Width Modulation) control method, a simulation model of the PMSM Space Vector Control System, which contains the double loop of speed and current, has been constructed based on the MATLAB/SIMULINK simulation environment. According to the artificial immune feedback theory and the approximation of the nonlinear function in the immune feedback system, with the help of fuzzy logic, a fuzzy immune PI controller has been made and harnessed in the speed loop. Under the three conditions: steady load startup, speed abrupt change, and load abrupt change, a series of contradistinctive simulation experiments are conducted and compared with the original PI controller respectively. The experimental results showed that the SVPWM control method with the fuzzy immune PI controller can not only make the motor run steadily, but also give it a superior speed performance and torque control characteristics. In addition, the control performance of the fuzzy immune PI controller showed a dramatically improvement compared with that of the traditional PI controller.
Review of Ejection Seat Electronic Program Controller
Authors: Wang Yu Fei , Han Li Lin , Wang Feng
Published: May 2014

Ejector seat program controller is the key device unfolded by the separation of the control people-seat and lifesaving parachute after the seat ejection from the machine, which is the main component of seat separation system. Compared with the mechanical program controller, electronic program controller has many advantages: small volume, light weight, time delay of high precision, good flexibility, strong power, easy to expand, the tremendous development potential and splendid testability. This paper respectively introduces the English MK series seats, American ACES series seat and Russian K-36Дseries seat electronic program controller, focusing on the TWZI type electronic program controller developed by China Aviation Life-saving Institute
Study on Surface Roughness of Milling Based on the Elastic-Plastic Deformation
Authors: Gao Guo Fu , Fu Zong Xia , Zhao Jing Zhui , Wang Yan
Published: May 2014

In order to achieve the work-piece surface quality control, Based on the formation mechanism of surface roughness and generating mechanism of material’s surface, considering the tool parameters and feed per tooth, to modify the maximum residual height’s formula of surface. Based on formation characteristics of machined surface and the elastic-plastic deformation theory of work-piece material, Got a simplified model of the elastic-plastic deformation of the work-piece surface,and according to the molecular-mechanical friction theory ,the calculation method was presented to investigate elastic-plastic deformation of machined surface . By combining the surface residual height calculation formula with the calculation method of elastic-plastic deformation, has built the theoretic model of the milling surface roughness , can forecast to the work-piece surface roughness, as well as provide theory basis for the selection of cutting parameters and optimization.
Research on the New Missile Electro-Hydraulic Actuation System Based on Two-Stage Speed Control Mode
Authors: Chen Hui , Fu Yong Ling , Chen Juan , Liu He Song
Published: May 2014

The performance of missile guidance and penetration ability is determined by the missile actuation system. According to the development trend of high performance and energy saving, the new missile electro-hydraulic actuation system based on two-stage speed control mode is presented in this paper, and then the operating principle and process are discussed in detail. Finally the accurate mathematical model of the new actuation system is established, and the influence of the different basic speed on the power loss and the dynamic performance are analyzed. The simulation results show that the purposes of maintaining the dynamic performance and reducing the zero-control current are achieved. Therefore, the new proposed scheme has a certain practical significance for the future development of the missile electro-hydraulic actuation system.
Experimental Study of Micro Milling Burr Control Based on Process Parameters Optimization
Authors: Sun Shu Feng , Yin An Chen , Wang Ping Ping , Zhang Qin Dong
Published: May 2014

With the development of the times, micro and small products are needed increasingly. The machining accuracy and surface quality are especially important to micro machining. However, in the micro milling, the size of the burr compared with that of the part is much greater than that of conventional milling. Moreover, it is difficult to remove micro milling burr by conventional deburring methods due to the small part size. The existence of burr will not only affect the match of parts, but also reduce the dimensional accuracy and surface quality of the work piece. Therefore, it is important to control and reduce micro-milling burr. Micro-milling experiments are carried out on the material of copper with micro-milling cutter diameter 0.5 mm. Micro grooves are milled with different cutting process parameters. The burrs generated under different conditions are analyzed using orthogonal test method. When the spindle speed and feed rate are constant, burrs increase with the increasing of cutting depth. Keeping the spindle speed and the depth of cut constant, burrs are generated increasingly with the increase of feed rate. And the decreasing of the spindle speed leads to the increase of burrs if the other parameters are constant. The experimental research provides reference for the burr control of micro-milling based on the optimization cutting process parameters.
Study on Distance Control System of Urban Traffic
Authors: Bao Pi Li , Wang Wen Mei , Zhu Yue Ying
Published: May 2014

Because of the characteristics of the urban traffic, which has higher traffic flow, low speed and flexible vehicle driving behaviors, the driving state of the vehicles must be changed frequently, so distance control system of urban traffic is put forward. The thesis built the best acceleration prediction, shortest security distance model, fuzzy controller and the whole vehicle model, and so on. Then the thesis made a simulation on distance control system of urban traffic, using Matlab/Simulink software, got some curve of different working situation.
The Lateral Shift of Refraction Sh-Wave on an Interface of Two Media
Authors: Wang An Ling , Liu Fu Ping
Published: May 2014

Using the phase shift of refraction coefficient of SH seismic wave at the interface of strata, we derived the lateral shift of total refraction SH-wave, drawn the curves of lateral shift. The results show that for glancing wave or angle of incidence being near the critical angle, the lateral shift are very large.angle of incidence the lateral shift is the same order of magnitude as the wavelength (period).
Research on Optimal Configuration of the Filter in Distribution Network with Distributed Power
Authors: Tang Ya Di , Xu Yong Hai
Published: May 2014

As there are a lot of inverters existed in distributed power coupled with nonlinear loads, the quality of energy power has been greatly affected, especially the harmonic problem. This paper presents an optimal configuration method of the filter based on the combination of genetic algorithm and differential evolution algorithm. The proposed method takes filter investment and energy loss cost as objective function. Then, it combines the advantages of both algorithms for optimizing allocation, numbers and parameters of active filter (APF) and passive filter (PF). Simulations are provided showing the validity of the proposed method.
Performance Evaluation Based Aviation Anti-Submarine Aircraft Projection Analysis Method
Authors: Yang Ming Hua , Wang Guo Gang , Zhang Ling , Han Xiao Ping , Liang Tao
Published: May 2014

Projection pursuit method will affect key performance indicators aviation anti-submarine aircraft into a one-dimensional projection value, given the quality of the evaluation of the various anti-submarine aircraft sample sorting, and has been the main performance index weighting, the method objectivity, For scientific evaluation of anti-submarine aircraft performance is important.
Scientific Research Paper Ranking Algorithm PTRA: A Tradeoff between Time and Citation Network
Authors: Hasson Mushtaq A. , Lu Song Feng , Hassoon Basheer A.
Published: May 2014

Most of the scientific research engines utilize the same way to rank scientific research papers (SRP), this way is highly depend on the citation network. The retrieved results of these engines for any keyword contain old papers with the highest citation value. In this paper, we proposed a new and easy to implement ranking algorithm for scientific research papers known as Paper Time Ranking Algorithm (PTRA). PTRA is a new ranking algorithm that depends on three factors to rank its results; paper age, citation index and publication venue. To construct and prove our ranking algorithm we created a web crawler that crawl different scientific search papers databases in the world to collect the information that PTRA needs. Unfortunately, some of this information was missing, such as, the impact factor of the journals. To collect this information, we created another crawler that search the Internet for these journals impact factors. However, to prove our ranking algorithm results, we have compared PTRA with Google scholar ranking algorithm. We used Google scholar, since it has more than 50 million papers and its own system can gather and collect papers in a faster way. Our comparison results show that, citation index has the highest impact on Google scholars ranking algorithm results. Unlike PTRA that gains the paper age a higher impact on the ranked results. However, PTRA depends on the citation index and publication venue to rank the results but with less impact than the paper age.
Effect of AIBA on Abrasive-Free Polishing of Hard Disk Substrate with Peroxyacetic Acid System Slurry
Authors: Ren Xiao Yan , Lei Hong
Published: May 2014

In the present study, the effect of 2, 2`-Azobis (2-methylpropionamidine) dihydrochloride (AIBA) on the abrasive-free polishing (AFP) of hard disk substrate was investigated. Polishing experiment results indicate that the material removal rate (MRR) of hard disk substrate polished in slurry containing AIBA and peroxyacetic acid (PAA) is obviously higher than that without AIBA. Furthermore, the acting mechanism of AIBA in AFP of hard disk substrate was analyzed. Auger electron spectrometer results demonstrate that the oxidation reaction occurred on the surface and formed a passivation layer. The potentiodynamic polarization tests show that AIBA can increase the corrosion rate of the hard disk substrate in PAA-based slurry, and accelerate the dissolution reaction of oxidation film, which lead to the improved MRR in AFP process.
Research and Evaluation of Bionics Shape Design Based on Cases
Authors: Guo Nan Chu
Published: May 2014

The paper proposes an ideal approach of shape design by using shape evaluation methods accurately. The paper proposes and tests the comprehensive fuzzy evaluation method using a case of two clips based on genetic algorithm and quantitative methods. By using this evaluation method, the shape details of a product could be improved gradually.
Reliability Estimates of Burr XII Components Using Masked Data under Progressive Type-II Censoring
Authors: Chen Mo , Shi Yi Min , Jin Li
Published: May 2014

We consider the series system with three independent and non-identical components, each of which has Burr XII distributed lifetime. Based on progressively type-II censored and masked system lifetime data, the maximum likelihood estimates (MLE) of the components parameters and reliability function are obtained. By introducing a latent variable, Bayesian estimators of the components parameters and the reliability function are also developed using Gibbs sampling method. Furthermore, in the numerical simulation study, the MLE and Bayesian estimates are compared under different removal probabilities and different times.
The Design of Solar Water Heating Remote Monitoring System Based on GSM Technology
Authors: Yuan Huan , Jiang Jin Yu , Wang Pei Ling
Published: May 2014

The solar water heating system is widely applied by all sectors of society because of its safety, health and environmental protection . To better improve the solar water heating system with professional monitoring of high degree of automation , convenience , simple maintenance , the remote control for the solar water heating system based on GSM is put forward , we proceed with the whole scheme design , and the hardware system and software system are also worked out . It proves by practice that the control system has some advantages of safe reliability, low design cost , automatic operation , data collection and analysis for water and electricity .
Abrasive-Free Chemical Polishing of Hard Disk Substrate with Benzoyl Peroxide-H2O2 Slurry
Authors: Jiang Ting , Lei Hong
Published: May 2014

The effect of benzoyl peroxide (BPO) as an initiator in H2O2slurry for abrasive-free chemical polishing of hard disk substrate was investigated. The results of abrasive-free polishing tests show that the introduction of BPO increases material removal rate (MRR) and decreases the value of Roughness (Ra). To further investigate the mechanism of abrasive-free polishing, electron spin-resonance spectroscopy (EPR) tests, auger electron spectrometer (AES) and electrochemical tests were conducted. Electron spin-resonance spectroscopy (EPR) tests show the concentration of radicals increase and promote the reaction on the surface of hard disk substrate. Auger electron spectrometer (AES) and electrochemical tests indicate chemical changes happen on the surface of hard disk substrate, and the formed oxide film may be sparse or porous. The results imply that the introduction of BPO can effectively improve the effect of abrasive-free polishing.
Traffic Jam Prediction through Elman Neural Network Based on Monte Carlo Simulation
Authors: Yu Ze Yuan
Published: May 2014

This paper simulates the traffic flow at upper stream intersection and the actual traffic flow at cross section of accident, and calculates the time for the queue to reach the upper stream intersection through Elman neural network. The result of 500 simulations shows that the probability for the time of the queue length being 140m: in [2.5min~3.5min] is 39.6% and in [3.5min~4min] is 52.0%. The total is 91.6%, which is highly precise. The prediction of queue length of post-accident traffic jam is of great importance to a quick recovery.
Research of the Wheat Modeling Problems Based on Creator
Authors: Wang Fei , Chi Rui Juan , Zhu Zhong Xiang , Mao En Rong
Published: May 2014

In order to making the virtual experiment results close to or equivalent to the real environmental effects, in addition to model realistic scenes, also need more accurate dynamic model. In this paper, based on research of hydraulic steering paddy and wheat combine harvester, first, used three-dimensional geometric model transformation technology to convert Pro/E model to a identified geometric model in VP virtual reality systems, second, used classical dynamics equations to build the mathematical model of this vehicle dynamics, finally, used VC++ programs to connect this two models, constructed a behavioral model of complete physics properties.
This behavior model is not only more realistic than the geometry model in motion, but also it follows the laws of physics movement. It can effectively strengthen the authenticity of virtual experiment, provide an important platform to start agricultural machinery virtual characteristics test, and this Modeling Method can provide a reference for other agricultural machinery virtual reality platform to build.
Prediction of Financial Revenue in Guizhou Province Based on Improved Grey Combination Models
Authors: Liu Hui
Published: May 2014

In order to predict accurately the total government revenue in Guizhou, two improved grey models were presented and have higher forecasting accuracy than original grey model, then combined with BP neural network model and higher precision is achieved; besides, the improved grey models integrated with Markov chain were used to forecast public finance budget revenue in Guizhou and provide obviously better accuracy than grey model. Finally, the Grey-Markov models were combined and then further improve the fitting precision. The results show that the methods of grey combination models are feasible and effective in forecasting the revenue.
A Complex Network Analysis of the Top College Coaches
Authors: Mao Yu Han
Published: May 2014

To find the best all time college coach, we analyze synthetically the college coaches of all time in the field of football. First, we collect the necessary data and build the index set which is composed of Win-Loss percentage, SRS, SOS, Championship index and Games. After screening the data with the vital indexes like Win-Loss percentage and Games, we select the coaches who are qualified to be the best one. In view of the effect of the time line horizon, we rank the coaches annually with grey relational analysis model based on Entropy Method. Since there are only a portion of coaches to be ranked in one year, we set up top coach network to link all coaches, in which vertexes refer to coaches. Applying the network, we calculate the prestige score and correct it by considering the effect of the strength of teams. With the help of prestige score, we gain the final rank.
The Characteristics Analysis about Objects of Corporate Blog Marketing in China
Authors: Wu Jian Ping , WEI Juan
Published: May 2014

This paper analyzed blog users’ physiological, psychological and behavioral characteristics by questionnaire.Conclusions is as follows. Blog users’ age assemblage is mainly from 18 to 50, emphatically ,18-30 years old users account for 70 percents. Most of blog users are highly-educated students and white-collar workers.Blog themes they are interested in are social news, health, food and entertainment and they don’t reject corporate blogs.Blogs of products types visited are various, which means that kinds of companies can use blog to carry out their marketing work.
Coach Evaluation Method Based on AHP
Authors: Cao Xin
Published: May 2014

In order to evaluate coaches, this paper established the model of comprehensive evaluation based on analytic hierarchy process (AHP). Firstly, I establish the hierarchical structure of the system; Secondly, for researching the influence of time line horizon in analysis, I divided coaches into several groups by their career time and calculated the weights of indicators of each group using entropy weight method; Finally, calculate the weight between the criteria layer and objective layer. Female coach data is difficult to find, so I select 100 college basketball male coach data. Put the data into model and get a score. The score showed the final result which can give us a sort of reasonable coach list. This model can reduce the influence of different time periods for evaluation of the coach.
Deformation Analysis of the Net Surface of the Mesh Antennas under the Gravity Action
Authors: Fan Ye Sen , Ma Xiao Fei , Li Zheng Jun , Li Tuan Jie
Published: May 2014

To research the deformation of the net surface of the mesh antennas under the gravity, a calculating model of a large hoop truss mesh antenna was studied using the whole coordinates interaction method (WCIM). The influence of the gravity and the initial tensions in the networks on the surface accuracy of the mesh antennas was discussed. To calculate the surface shape in the agravic environment, a cup-up and cup down procedure was developed. The influence of the gravity on the surface accuracy decrease when the initial tensions in the networks increase. When the angle between the antenna and the horizontal plane (AAHP) varies, the nodes of the net surface fluctuate in the certain ranges respectively in the local coordinates fixed on the antennas. The conclusions are useful for the adjustment for the net surface accuracy on the ground.
Summarization of Terramechanics Research on Screw-Propelled Vehicle
Authors: Guo Xiao Lin , Liu Jie , Liu Guo Qiang , Zhao Yan
Published: May 2014

It is of great significance for screw-propelled vehicles to solve the problem of driving on the soft ground. In this paper, the development of screw-propelled vehicles both at home and abroad is reviewed; the domestic and foreign propulsion theory research results of scholars are summarized based on terramechanics; the deficiency of the modern research methods is analyzed. At last, some discussions on study methods are made in particular.
Human Arm’s Muscle Force Estimation Model Based on Fuzzy Theory
Authors: Naeem Usama J.
Published: May 2014

Muscle force estimation, is important in order to understand human control strategies, rehabilitation, motion analysis and human-machinery interfacing. To estimate the force, bio-signals analysis is used. Bio-signals enable signal recognition and analysis of muscle action and it is used to estimate muscle force. In this work, a method to estimate human muscle force is proposed. This model, which is based on Fuzzy Logic Theorem, is fast and easy to implement. Fuzzy Model process a raw of rectified smoothed electromyography (RSEMG) signal and extract muscle force. Our model is a general one, it can use for any muscles. To prove that, we used biceps brachii muscle of the left and right arms and two different arm muscles as validation. Our results, demonstrate that the new model improves the accuracy of muscle force estimation. This model can efficiently extract muscle force features from (EMG) signals. Our results showed that algorithmic regression exceeds 99%. The mean square error (MSE) results for Fuzzy Model was very small (MSE equal to 1.11x10-08).
Hall-Petch Relationship in an Al-Mg-Sc Alloy Subjected to ECAP
Authors: Dubyna Andrii , Mogucheva Anna , Kaibyshev Rustam
Published: May 2014

Effect of extensive grain refinement on mechanical properties of an Al-Mg-Sc alloy subjected to equal-channel angular pressing (ECAP) at 300°C is considered in detail. It was shown that the Hall-Petch relationship with the coefficient, ky, of 0.2 MPa×m1/2 is valid in a wide strain range despite a great difference in deformation structures. Volume fraction of fine grains with an average size of ∼1 μm gradually increases with strain. It is caused by the fact that additive contributions of grain size strengthening and dislocation strengthening to the overall strengthening take place in this alloy. Upon ECAP the extensive grain refinement is accompanied by increasing dislocation density. Superposition of deformation and structural strengthening mechanisms provides achieving very high strength in the alloy. It was shown that ECAP at 300°C has no remarkable effect on a dispersion of coherent dispersoids. Al3(Sc,Zr), which gives a significant contribution to overall strength through dispersion strengthening. Contributions of different strengthening mechanisms to overall strength of the material are analyzed.
Electrothermomechanical Processing of High Carbon Steels
Authors: Elliott-Bowman Bernadette , Cook A.C. , Brown P. , Qin Rong Shan
Published: May 2014

Passing high density electric current through some metals has been shown to induce microstructural changes, such as grain refinement. Known as electropulsing, the process has previously been successfully applied to cold-drawn pearlitic steel wire over a very short treatment period (current density >103 A·mm-2 and pulse width <10-4s) and with low energy expenditure. Once optimised, electropulsing treatment may offer potential time-and energy-saving advantages over traditional grain refinement techniques. However, to date, very little research on the effects of electropulsing on pearlitic steel exists in the literature and is limited to steel wire. The current work was conducted to determine whether electropulsing treatment is capable of producing similar grain refinement and spheroidisation behaviour in the microstructure of cold-deformed high carbon pearlitic steel sheet (0.92wt%C). High current density electropulsing treatment was applied to pearlitic steel samples of 40 to 70% rolling reduction for 50 or 100 pulses. The electropulsing treatment did produce microstructural changes in pearlitic steel plate that was similar to that observed in pearlitic steel wire over a relatively short treatment time. These changes involved grain refinement and spheroidisation and were enhanced with increasing cold rolling reduction.
Effect of Zr Addition on Martensitic Transformation in TiMoSn Alloy
Authors: Endoh Kazuki , Tahara Masaki , Inamura Tomonari , Kim Hee Young , Miyazaki Shuichi , Hosoda Hideki
Published: May 2014

The effects of Zr addition on martensitic transformation and the lattice parameters of α” (orthorhombic) martensite and β (bcc) phase were investigated in Ti-3mol%Mo-6mol%Sn based alloys containing up to 4mol%Zr using θ-2θ X-ray diffraction measurement (XRD) and differential scanning calorimetry (DSC). It was found by XRD that orthorhombic α” martensite phase is formed when Zr content is 0 to 2mol% while bcc β phase also existed in the alloy containing 2 to 4mol%Zr. Based on the lattice parameters in α” martensite and β parent phases evaluated, the transformation strains between α” and β phase calculated become slightly small with increasing Zr content. DSC revealed that, with increasing Zr content, reverse martensitic transformation start and finish temperatures decreased down to 410K with a rate of-30K/mol%Zr. It is concluded in the Ti-Mo-Sn alloy system that Zr addition stabilizes β phase and that Zr addition is effective to control martensitic transformation temperature without changing the transformation strains largely.
Residual Stress Measurements in Multi-Pass Welded High Strength Steel Using Energy Dispersive Synchrotron X-Ray Diffraction
Authors: Gao H. , Huizenga R.M. , Dutta R.K. , Amirthalingam M. , Hermans M.J.M. , Buslaps T. , Richardson I.M.
Published: May 2014

Six pass welds were made on a 16 mm thick high strength quenched and tempered structural steel plate (S690QL1, Fe-0.16C-0.2Si-0.87Mn-0.33Cr-0.21Mo (wt.%)). Depth resolved measurements in two orthogonal directions were carried out using energy dispersive synchrotron X-ray diffraction at the ID15 beamline of the European Synchrotron Radiation Facility. The strains were calculated from the shift in the local d-spacing for four bcc planes ({200}, {211}, {220}, {310}). The planar stresses were calculated from the biaxial Hooke’s law, using the diffraction elastic constants of the individual planes. A two dimensional cross-sectional residual stress map with a depth resolution of 2 mm was obtained. Transverse compressive stresses were found at the weld toes and root. Transverse tensile stresses were present in the middle of the plate. Longitudinal tensile stresses concentrated along the fusion line. This work describes the procedures to obtain the depth resolved residual stress map and the generated results provide necessary information to validate thermal mechanical finite element model of multi-pass welding.
Effects of Thermomechanical Treatments on Microstructure and Mechanical Behavior of HCS/LCS Bimetal
Authors: Gao Xing Jian , Jiang Zheng Yi , Wei Dong Bin , Li Hui Jun , Jiao Si Hai , Han Jing Tao
Published: May 2014

A high carbon steel (HCS) and low carbon steel (LCS) bimetal was fabricated by centrifugal composite casting. Two different thermomechanical treatments (TMT1 and TMT2) were employed to improve the mechanical properties of the bimetal. TMT1 process includes 60% of overall reduction by hot compression with temperatures of 1100 and 800 oC, respectively. While TMT2 process involves 60% of overall reduction using the two-step deformation method, which is a combination of non-isothermal compression cooling from 1100 to 800 oC and isothermal compression at 800 oC. The flow stress behavior, microstructural evolution and microhardness variation were analysed. Experimental results show that both TMT processes contributed to the improvement in mechanical properties resulting from a refinement of the grain size and an increase of density of pearlitic lamella in HCS layer. However, TMT2 process gave a better efficiency and a more significance in improvement of properties with the evidence of the same overall reduction leading to a higher microhardness.
Relevance of Hot Ductility Tests to Crack Sensitivity during Continuous Casting of Steel
Authors: Großeiber Simon , Gusenbauer Christian , Ilie Sergiu , Requena Guillermo C. , Kozeschnik Ernst
Published: May 2014

Hot tensile tests are performed on a Ni-alloyed steel after solution treating and cooling to test temperatures ranging between 600 and 950°C at strain rates of 3∙10-4 and 3∙10-3/s. The critical reduction of area (RA) for damage formation is determined by means of laboratory X-ray computed tomography. The results are compared with the corresponding RA at fracture traditionally used for assessing hot ductility and crack sensitivity during straightening of the slab. We demonstrate that using RA at fracture is inadequate for evaluating hot ductility in the austenite phase region at temperatures varying with the strain rate. Hot ductility curves more relevant for slow strain rate deformation are determined.
Influence of the Partitioning Treatment on the Mechanical Properties of a 0.3C-1.5Si-3.5Mn Q&P Steel
Authors: Hajy Akbary Farideh , Santofimia Maria Jesus , Sietsma Jilt
Published: May 2014

The Quenching and Partitioning (Q&P) process is a promising method for developing steels with superior mechanical properties. This process includes quenching an austenitic microstructure to form a controlled fraction of martensite, an isothermal treatment (partitioning step) aiming for the partitioning of carbon from martensite to austenite and a final quench to room temperature. This paper analyses the concurrent processes of carbon partitioning and martensite tempering during the partitioning step of a 0.3C-1.5Si-3.5Mn (wt.%) Q&P steel. The influence of the martensite tempering and the carbon partitioning on the tensile strength as well as on the uniform and post-uniform elongation of the developed Q&P microstructures is investigated.
Characterization of Morphology Controlled Fluorine-Doped Tin Oxide Thin Films
Authors: An Ha Rim , Ahn Hyo Jin
Published: May 2014

We controlled morphologies of F-doped SnO2 (FTO) thin films via an electrochemical method. To obtain rough and porous surface of the FTO thin films, a potentiostat/galvanostat was used. Field-emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) were employed to demonstrate the morphological changes of FTO surface. The electrical and optical properties of the FTO thin films were analyzed using Hall effect measurement system and UV-vis spectrophotometry. Also, morphology controlled the FTO thin films would be applied to dye-sensitized solar cells.
Possible Orbital-Ordered State in the Highly-Correlated Electronic Material Sr1-xCexMnO3
Authors: Hanaoka Takehiro , Inoue Yasuhide , Koyama Yasumasa
Published: May 2014

The simple perovskite manganite Sr1-xCexMnO3 (SCMO) has a highly-correlated electronic system with a three-dimensional character. Because the presence of orbital-ordered states of eg electrons can be expected in SCMO, the crystallographic features of SCMO samples with 0.09 ≤ x ≤ 0.20 have been investigated mainly by transmission electron microscopy. In addition to fundamental reflections due to the simple perovskite structure, their electron diffraction patterns at room temperature exhibited both the presence of superlattice reflections at k = ()c in the cubic notation and the splitting of fundamental and superlattice reflections. The careful analysis of these reflections indicated that the superlattice reflections originated from the R25-type rotational displacement of oxygen octahedra about one of the <100>c directions. On the other hand, the splitting of the reflections was found to be due to a {110}c banded structure consisting of two tetragonal bands with different c/a values.　Because one of two tetragonal bands had the c/a value of about 1.028, the splitting reflects the introduction of the Jahn-Teller distortion as a response of a lattice system to orbital ordering. It is thus understood that the C-type orbital ordering of eg electrons should be involved in the state at room temperature for 0.09 ≤ x ≤ 0.20 in SCMO.
Optimization of a Closed Die Forging Process to Manufacture a Gear Wheel by the Use of a Response Surface Model
Authors: Henke Thomas , Hirt Gerhard , Bambach Markus
Published: May 2014

Heavy-duty components used in the automotive industry, in wind turbines and in many other industrial applications are often produced using hot forging processes. Nowadays the design of hot forging processes aims for the optimization of process efficiency on the one hand and final mechanical product properties on the other hand.
Excellent mechanical properties needed for hot-forged components e.g. high load capacity and high fatigue resistance depend on a fine homogeneous microstructure distribution across the final product’s cross-section. Efficiency in hot forging can be optimized by increasing the temperature during processing, which allows for lower forging loads and lower die stresses, thus improving die life in terms of mechanical fatigue. To guarantee for a fine homogenous microstructure across the cross section of the forged good, dynamic recrystallization (DRX) has to be initiated during deformation and Grain Growth (GG) has to be avoided during dwell times and cooling.
Due to the high computational costs of finite element simulations an optimization aiming for lowest possible forging loads and finest possible grain sizes is very time-consuming. In this paper a Response Surface Model (RSM) of the forging process is introduced, which allows for much faster evaluation of the outcome of forging simulations, albeit by interpolation of simulation results, and thus allows for optimization. The information required to create the RSM is obtained by Design Of Experiments (DOE) techniques using an FE-model of the forging process which was calibrated earlier. The process variables considered include the initial temperature of the billet and the die kinematics. Subsequently, an optimization algorithm is combined with the RSM to find the design variables giving minimum possible loads during deformation and finest possible grain sizes in the forged product. The RSMs results are validated by the use of the existing FE-model.
A Phase-Field Model for the Formation of Martensite and Bainite
Authors: Arif Tansel T. , Qin Rong Shan
Published: May 2014

The phase field method is rapidly becoming the method of choice for simulating the evolution of solid state phase transformations in materials science. Within this area there are transformations primarily concerned with diffusion and those that have a displacive nature. There has been extensive work focussed upon applying the phase field method to diffusive transformations leaving much desired for models that can incorporate displacive transformations. Using the current model, the formation of martensite, which is formed via a displacive transformation, is simulated. The existence of a transformation matrix in the free energy expression along with cubic symmetry operations enables the reproduction of the 24 grain variants of martensite. Furthermore, upon consideration of the chemical free energy term, the model is able to utilise both the displacive and diffusive aspects of bainite formation, reproducing the autocatalytic nucleation process for multiple sheaves using a single phase field variable. Transformation matrices are available for many steels, one of which is used within the model.
Ultrasonic Spot Welding of Galvanized Steel Sheet
Authors: Kaneko Naho , Sasaki Tomohiro
Published: May 2014

Ultrasonic spot welding of galvanized steel sheets has been conducted to investigate formation process of the weld microstructure, and effect of zinc coat on joint property. The joint strength showed a rapidly increase at the weld time of 0.8s, and it has the maximum value over 1.0 s. In the weld time range from 0.1s to 0.8s, fracture occurred in zinc coat/ steel interface. In contrast, the fracture partially occurred in the base steel in the weld time over 1.0s, and concaves in which the steel substrate of one specimen partially remains on the other specimen were observed. The formation process of weld microstructure of ultrasonic welding was proposed to be a two-steps process. First, zinc coat in the interface was mechanically removed by the vibration and clamping force, and some zinc particles dispersed in the weld interface. Second, the zinc particles melted due to the friction, and partially bonded regions were simultaneously formed around the zinc particles. The partially bonded regions were stirred with the steel substrate as the weld time increased. The joint strength increased by development of the stirred zone. At the weld time over 1.2s, the joint strength decreased due to growth of crack around the stirred zone.
The Age-Hardening Mechanism of Nanocrystalline Ni-P Alloys Synthesized by Electrodeposition
Authors: Kasazaki Yosuke , Miyamoto Hiroyuki , Hiroshi Fujiwara
Published: May 2014

Strengthening mechanism of age-hardenable electrodeposited Ni-P alloy was investigated focusing on the role of Ni3P precipitates in nanocrystalline structures. Specimens were synthesized by electrodeposition followed by aging treatment at temperatures raging from 473 to 773 K. As-electrodeposited structures became only Ni phase and Ni3P precipitated by the subsequent aging treatment. Distribution of grain size of Ni matrix was examined in detail by field-emission type transmission electron microscopy. The specimens became harder with higher P content after the electrodeposion and aging treatment. After the aging treatment 573 K or bellow, average grain size of Ni matrix was under 10 nm. On the other hand, after aging at 673 and 773 K both the grain size of Ni matrix and Ni3P particle size grow to be comparable. It is considered the hard interphase boundary to the dislocation slip is responsible to the hardening rather than the classical precipitation hardening.
The Effect of Si on the Intermetallics Formation during Hot Dip Aluminizing
Authors: Lemmens Babs , Corlu Beril , de Strycker Joost , Verbeken Kim
Published: May 2014

When applying an aluminium coating on a steel substrate, the corrosion resistance of aluminium is combined with the mechanical properties of steel. There are different ways to coat steel among which hot dipping is the most applied because it is technically feasible in large volumes and economically the most beneficial one. Although aluminized steel accounts for about 5% of the total world production of all hot dip coated steels, the interactions between the molten aluminium and steel substrate are not yet completely understood. During hot dipping, several intermetallic layers are formed between the outer nearly pure aluminium layer and the steel substrate. These layers mostly comprise of a thin FeAl3 and a thicker Fe2Al5 layer. The thickness of these intermetallic layers must be kept minimal since they embrittle the coating. Thickness reduction of the intermetallics is mainly realized by silicon addition to the aluminium bath. In this work, the formation of intermetallic layers was investigated for a deep drawing steel grade which was hot dipped in aluminium baths with six different Si contents ranging from 1 to 10 wt%Si. The Si-addition was demonstrated to lead to a decrease in the thickness of the intermetallic layers and a flattening of the intermetallic-steel interface. An increase in Si also led to the formation of other intermetallic compounds, which are investigated by a systematic analysis by scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) on multiple samples and discussed in terms of the Si-effect on a possible formation mechanism for the intermetallics.
Effects of Electropulsing on the Microstructure Evolution of 316L Stainless Steel
Authors: Lu Wen Jun , Qin Rong Shan
Published: May 2014

Thermal crack initiation and pitting corrosion are frequently caused by the formation of the secondary phases such as sigma phase, delta-ferrite phase, carbides and secondary austenite phase in steel. Traditionally, heat treatment is used to minimize these detrimental effects of the secondary phases. In this study, we have applied pulse to the 316L stainless steel and observed the considerable effects. In comparison to the heat treatment, the electropulsing can effectively suppress the precipitation of the secondary phases in a temperature range (1161 K–1173 K). Austenite grain size becomes larger under electropulsing compared to the heat treatment at annealing temperatures due to enhanced interface migration. The kinetic and thermodynamic aspects of electropulsing can be used to explain the effects of electropulsing on the evolution of microstructure for 316L stainless steel.
Influence of Deformation Rate on Mechanical Response of an AISI 316L Austenitic Stainless Steel
Authors: Calmunger Mattias , Chai Guo Cai , Johansson Sten , Moverare Johan
Published: May 2014

Austenitic stainless steels are often used for components in demanding environment. These materials can withstand elevated temperatures and corrosive atmosphere like in energy producing power plants. They can be plastically deformed at slow strain rates and high alternating or constant tensile loads such as fatigue and creep at elevated temperatures. This study investigates how deformation rates influence mechanical properties of an austenitic stainless steel. The investigation includes tensile testing using strain rates of 2*10-3/ and 10-6/s at elevated temperatures up to 700°C. The material used in this study is AISI 316L. When the temperature is increasing the strength decreases. At a slow strain rate and elevated temperature the stress level decreases gradually with increasing plastic deformation probably due to dynamic recovery and dynamic recrystallization. However, with increasing strain rate elongation to failure is decreasing. AISI 316L show larger elongation to failure when using a strain rate of 10-6/s compared with 2*10-3/s at each temperature. Electron channelling contrast imaging is used to characterize the microstructure and discuss features in the microstructure related to changes in mechanical properties. Dynamic recrystallization has been observed and is related to damage and cavity initiation and propagation.
Effect of Axial Force on Corrosion Behavior of SUS304 Stainless Steel Bolt
Authors: Nakamura Yuki , Yoshihara Shoichiro , Mac Donald Bryan J. , Galvin Emmet
Published: May 2014

In this study, the influence of mechanical and electrochemical phenomena on the corrosion behavior of SUS304 stainless steel bolt was investigated. A corrosion test bench was developed and the influence of the initial axial strain, the corrosion type and the corrosion potential on the nature and kinetics of the corrosion processes was examined. It was carried out that the corrosion experiment of different the initial axial force and the corrosion potential. In addition, we obtain the stress distribution by the finite element analysis (FEA), after that we compared the stress distribution to the experimental results of the corrosion distribution.