bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-Reservoir Ecological Operation Using Multi-Objective Particle Swarm Optimization
Authors: Liu Wei Lin , Liu Li Na
Published: September 2014

Traditional reservoir operation ignores ecological demands of rivers. This would probably lead to degradation of river ecosystem. In order to alleviate the influence of reservoirs on river ecosystem, multi-objective reservoir ecological operation was proposed from perspective of maintaining the river ecosystem health. Multi-objective mathematical model of multi-reservoir ecological operation was established. A multi-objective particle swarm optimization (MOPSO) algorithm was introduced to generate a set of Pareto-optimal solutions. In addition, to facilitate easy implementation for the reservoir operator, a simple but effective decision-making method was presented to choose the desired alternative from a set of Pareto-optimal solutions. Finally, the proposed approach was applied to the ecological operation of the reservoirs at the main stream of Xiuhe river in Poyang Lake basin in China. The results show that the proposed approach is able to offer many alternative policies for the water resources managers, and it is a viable alternative to solve multi-objective water resources and hydrology problems.
Method of Quick-Survey of the Phytocoenosium in Urban Green Space
Authors: Tan Ying , Yao Qing Shan , Ji Hong Xin , Wei Li Yuan
Published: September 2014

By comparing research methods in the different disciplines of botany, military science and mathematics, in order to discover the phytocoenosium structure of urban green space, this paper induced a simple and practical method, which included four steps, i.e., quadrats selection, integrity indicators surveying, individual indicators surveying and type identification. This method applies to those research activities with less precision need and compact time.
A SD Prediction Model Based on System Dynamics of Social Economy and Transportation Industry
Authors: Xia Xiong , Jiang Ming Qing
Published: September 2014

This paper uses vensim to establish a SD prediction model of transportation and social economy, the model considers passenger transport capacity, cargo capacity, population, GDP and other major factors. Base on data in nearly ten years, the prediction results verify S-T SD model is ture and effective,and get the time-node that the growth rate of passenger capacity satisfied the shortage of Passenger transport capacity in different sensitivity parameter A.
Research on Optimization of the Passenger Train Departure Time Domain for Reducing Passenger Train Stock Amount
Authors: Cong Jing Shuai , Zhang Yu Zhao
Published: September 2014

A method was proposed to reduce the amount of train stock by optimizing the passenger train departure time domain. The objective function is the minimum total turn-round time of passenger train stock. The constraints include the dwell time in departure station and turn-back station, the interval time. The optimization model of the passenger train departure time domain was built. Design the heuristic algorithm to solve the proposed model. Taking the Zhengzhou station as an example, each passenger train departure time domain is calculated by utilizing the proposed model. Comparing the calculated departure time domain with the real departure time, the effectiveness of the model is calculated.
Research on Speed Limit of Highway Expansion Project Construction Zone
Authors: Hu Qing Guo , Xu Shu Yuan , Song Xin Zhi , He Zhong Ming
Published: September 2014

The reasonable speed limit would reduce the detrimental impact on the driving safety and traffic jam in Highway expansion project high slope work zone. The study based on the investigation of Liu Nan highway’s traffic capacity, speed, traffic flow and other related index, which researched the vehicles queuing length of the different lane width in expansion project construction zone. The result is that 1/2 lane occupied need limit speed step by step in the warning area, 1/3 lane occupied limit 60km/h and 1/4 lane occupied limit 80km/h.
Study on Stray Current Protection for Lanzhou Rail Transit Line 1
Authors: Li Ya Ning
Published: September 2014

Stray current is one of the crucial factors affecting safety running for train. It is the first Rail Transit Line for Lanzhou. According to the local geological data, line direction, crossing Yellow River, building conditions, some measurements were put forward to restrict the stray current leakage in Lanzhou Rail Transit Line 1. Especially, it is very important to prevent the water permeating into the soil connecting to the railway. Corresponding protection scheme was laid down in this paper. The protection scheme in this study has very important role in the safe operation, system improvement and maintenance process for Lanzhou Rail Transit Line 1.
Urban Rail Transit Network Fare Analysis
Authors: Yang Ke , Jia Jun Fang
Published: September 2014

This article analyzes the relevant factors of urban rail transit fare pricing. Some cities with metro network were selected to study the level of rail transit fares. By analyzing and comparing the characteristics of the networks, this article draws some conclusions and recommendations about the ticket pricing of urban rail transit.
Study on Stability of Last Train Connection under Delays on Urban Rail Transit
Authors: Li Yuan Pei
Published: September 2014

The stability of the last train connection under delays directly reflects the coordination of urban rail network. Based on the connection of scheme of last trains, this paper analyzed of the impact of the delay on the transfers and established a static evaluation index system of the impact on transit network. Furthermore, the paper evaluated a rail transit network under different last train delays. Ultimately, the evaluation results could be got by this method, which could be used to analyze the trend of the evaluation results over delay time.
A GPS Data Based Monitor Model of Unoccupied Taxis at Transportation Hubs
Authors: Che Xiao Lin , Weng Jian Cheng , Yu Quan , Xu Tian Yu
Published: September 2014

Taxis account for a large percent of urban public passenger transport. This research proposes a monitor model of analyzing unoccupied taxis at a defined area. By scientific analysis of taxi GPS data precision and quality, 16,255 valid taxis in register list were filtered, and two coefficients were introduced to correct the taxi monitoring model. Based on the location reports of valid taxis, the number of unoccupied taxi which was able to dispatch to meet passengers’ demands can be predicted. Take the terminal 3 of Beijing Capital International Airport as a case study, the field investigation results show that the precision of model reached 87.25%. It provides reliable systematic support and alert for a low taxi number when there comes up large taxi travel demand during the peak period or under severe weathers.
Short-Time Passenger Volume Forecasting of Urban Rail Transit Based on Multiple Fusion
Authors: Li Ji Wei
Published: September 2014

Aiming at enhancing the estimation performance of passenger volume for urban transit, based on analysis of horizontal and vertical characteristics and principles of multiple fusion technology, respectively, establishing 3 forecast models, and compared with the measured data. The results show that, the proposed new method has a comparative advantage to reduce prediction error.
Study on NTCIP-Based Architecture of Data Center for Transportation Information System in China
Authors: Song Lu , He Shang Lu , Hu Yong Kai , Zhang Jian
Published: September 2014

Data center, which is the basis for the development of transportation information, has the basic function of data storage, processing, data exchange and information sharing. In China, it is a preliminary stage of the design and construction for data center. Difficulties like effective data sharing and executive information service are still exist. In this paper, according to the transmission of data sharing and system architecture design of National Transportation Communications for ITS Protocol (NTCIP) in U.S., the mapping relation between NTCIP and data center architecture is analyzed. The NTCIP-based architecture of data center in transportation information system on freeway is proposed, combined with the information needs of the freeway in Jiangsu Province, China. This study can be used to provide a reference for the data center construction.
Logit Model-Based Research on Market Position of Jing-Hu High Speed Rail
Authors: Jiang Jin Liang , Zhu Hong Wei , Wang Xiao Jia
Published: September 2014

This paper aims to analyze how the introduction of high-speed rail (HSR) influences the market structure in the Beijing-Shanghai passenger corridor of China.First of all, through the analysis of travel behavior characteristics of this passenger corridor, the logit model is constructed to analyze the market share among the modes of high-speed rail (HSR), existing railway lines, air transportation and highway. Secondly, based on the survey data , the parameters of logit model are calibrated by using transcad software.Then the market share ratio for all transport modes of Beijing-Shanghai passenger corridor is calculated through the calibrated logit model. Finally, this paper makes some research on how the air transportation influences the new HSR in terms of market share. This paperprovides several scenarios of market share ratio of high-speed rail (HSR) and makes a comparison among thembased on the hypothesis that the market influence of the air transportation is improved by adopting efficient and effective measures.
A Method for Reconstructing Vehicle - Vehicle Impact Accidents Based on Pc-Crash
Authors: Zhang Yong Gang , Xu Jian Min , Zou Tie Fang , Liu Yu
Published: September 2014

To reconstruct accident succinctly and scientifically, four steps of vehicle-vehicle impact accident reconstruction based on Pc-Crash were discussed, including accident scene reconstruction, vehicle modeling, accident reconstruction, result analysis and verification. Three accident scene reconstruction methods were proposed. Key attention was paid to methods which can reduce difficulties of accident reconstruction, such as drive model, equivalent energy speed (EES) database and collision optimizer. Finally, a case study was conducted, which confirmed that the proposed four steps can simplify vehicle-vehicle accident reconstruction while maintaining satisfying objectivity and reliability. This paper can contribute to the better application of Pc-Crash to traffic accident reconstruction.
Research and Application on Technology of Flood-Storage and Flood-Detention of Coal Mining Subsidence Area of Suzhou Coal Mine
Authors: Zheng Jia Zhong , Zhu Mei , Wang Zheng Long
Published: September 2014

The artical is based on the investigation of the basis of the status quo of Zhuxianzhuang and Luling coal mining subsidence area in Anhui province Suzhou city(hereinafter referred to as the "Zhu Lu subsidence area"), a preliminary analysis of the dynamic change trend of detention space in Zhu Lu subsidence area, and based on the hysteresis storage conditions of subsidence area, use the flood routing model to simulate the hysteresis effect of storage at different subsidence scenarios of different frequency flood. Finally, using the experience type channel evolution model and peak delay routing model further revealed storage effect on flood process of Zhu Lu subsidence area.
Analysis of Typical Defects in SRS by Taking the Recall Cases as Examples
Authors: Yin Yan , Feng Yong Qin , Zhang Xiao Rui , Song Li
Published: September 2014

With the development of highways and the improvement in vehicle performance, vehicle speed has become faster and faster, causing more and more frequent accidents. As an auxiliary configuration of vehicle body’s passive safety, SRS (supplemental inflatable restraint system) often serves as a key component providing protection for both the driver and passengers and thus receives increasing attention. By taking the latest recall case base in 2012 and 2013 as a blue print, this paper analyzes 111 SRS-caused recalls implemented by China, the US, the EU and Australia respectively, discusses main defect forms of SRS, and finally proposes the improvement suggestions on safety techniques in design and manufacturing.
Development of Detection Research on Fatigue Driving
Authors: He Xiao Jun , Liu Jing , Yi Zhen Di , Yang Yuan Quan
Published: September 2014

This paper presents the current most common fatigue-driving detection methods. The advantages and disadvantages of these detection methods are compared with. Moreover, several major products of the current fatigue detection are listed briefly. Furthermore, the development trends of driving-fatigue detection technology are prospected. The author believes that driver fatigue testing standards need to be further clarified and the non-contact detection method of driving-fatigue needs to be developed deeply. Information fusion is an important orientation for driving fatigue and we should design the cost-efficient detection products for fatigue-driving.
Duration Time of Freeway Incidents
Authors: Gao Chao , Qin Li Yan , Liu Ting Xin , Zhang Liang Zhi
Published: September 2014

One-way traffic blocking on four-lanes freeway was divided into three types in this paper, such as blocking on outside lane, inside lane and double lanes. Then one lane blocking was conducted under five kinds of volume and six kinds of blocked time, moreover two lanes blocking was conducted under seven kinds of volume and five kinds of blocked time, and the simulation conclusions were obtained respectively . The relationship models among blocking duration time, upstream volume and blocking time are established and tested. This study can be used to predict the duration time of the freeway blocking under certain volume or blocked time.
Macroscopic Simulation of Traffic Flow on Continuum Urban Networks
Authors: Jiang Yan Qun , Zhou Shu Guang
Published: September 2014

In this paper, a macroscopic model is applied to simulate dynamical features of traffic flow on a continuum urban network. This model is described as the two-dimensional Lighthill-Whitham-Richards model coupled with a reactive dynamic user-optimal route choice model. Numerical results visualize the ability of the model to predict some macroscopic characteristics of traffic flow on networks, i.e. the spatial distribution of flow density and travel cost of users, as well as to capture traffic congestion build-up and dissipation.
Social Traffic Function Study: The Empirical from IT Reform to Trip Behavior Change of Urban Residents
Authors: Li Ya Ting , Zhong Wei Zhu
Published: September 2014

Through the mediating effect analysis of society informatization, discuss the internal relation in the influence of IT transformation on residents' travel behavior change, and then find the influence path. Proposes the hypothesis research model and verifies it empirically based on the “IT transformation and public travel” behavior survey in Tianjin (663). The result shows that IT transformation not only has a directly marked impact on changing travel behavior of residents; information literacy and information resources play a role of mediating effect between the IT transformation and residents’ travel behavior change.
A Brief Talk of Structure Designing and Actual Application of Microgrid
Authors: Liu Cheng , Li Zhe , Wang Hui , Xia Lei
Published: September 2014

Nowadays we advocate low carbon economy, energy conservation and emission reduction, emphasize the harmonious development of human being and the nature. As a result, the clean, efficient microgrid with flexible use mode is widely payed attention to. A microgrid uses natural resources as electric power source, it can effectively relieve burden of the grid, and help to solve the problem of transporting electricity from the grid to remote suburb area. How to design the structure of a microgrid to make it run harmoniously with the grid while using clean energy efficiently and controlling the microgrid reasonably is the key to developing microgrid technique. Based on the construction of microgrids in China, this paper concludes the main key techniques in designing and constructing of microgrid, introduces several typical microgrids in China, and makes an outlook to the designing of microgrid structure and technique development.
Application Analysis of Water Loop Heat Pump System Energy Conservation of a Sports Training Center
Authors: Wang Hong Li
Published: September 2014

A sports training center training venues and office building adopting water loop heat pump system (WLHPS) are taken as examples, combined with the practical problems in design and operation, to analysis the operation characteristics of the air conditioning system and its advantages and disadvantages, and the energy saving operation strategy is put forward to further reduce energy consumption.
Architectural Construction for Energy Efficiency of Rural Dwellings in Ningxia Hui Autonomous Region
Authors: Liang Rui , Lei Lin , Zhu Yi Yun , Zhang Qun
Published: September 2014

Aiming to improve the rural vernacular indoor thermal conditions in winter and achieve the energy-saving objective 65%, the traditional local-style dwelling houses are investigated and the energy consumption of exterior-protected constructions is analyzed in Ningxia. The vulnerable spot of building energy consumption is found, while we discuss the shortage of traditional local-style dwelling houses in construction and design. Based on the social economic conditions of Ningxia, we put forward the improvement design of rural dwelling construction. Meanwhile, we analyze and calculate the thermal engineering performance of new construction design, which demonstrated that the scheme is reasonable and effective.
Study on the Influence of Shallow Groundwater Source Heat Pumps on Groundwater Quality in Weifang, China
Authors: Huang Qiang , Wang Wei Ping , Deng Hai Yan
Published: September 2014

Selecting 4 shallow groundwater source heat pump (GSHP) projects as research objects in Weifang city of Shandong province, China, the groundwater quality in the project area was, observed and analyzed by sampling continuously. The results show that the concentrations of chloride and the total hardness are relatively stable, and there are no apparent changes; In the change curve of TDS in different kind of shallow GSHPs, the worse the sealing condition of the project, the more obvious the rising trend of TDS; The concentration of nitrate is generally on the rise, and the concentration of ammonia appears in the trend of first increased then decreased. Therefore, in the region, the shallow GSHPs are not completely free from contamination in the current technology conditions and the application should be controlled and managed strictly. The observation of shallow GSHPs still need be conducted in a long term.
Some Issues about Low Carbon Architecture
Authors: Jia Zhi Feng
Published: September 2014

In this paper, the author is focusing on low-carbon architecture design with passive strategies and also applying the passive principles to strength the usage of natural resource. Meanwhile, this paper is emphasizing different types of low-carbon designing from the aspects of structure, materials and HVAC system. The goal of the paper is to promote the usage of the low-carbon architecture.
A Perspective of Low Carbon: On the Design of Public Facilities
Authors: Dong Cui
Published: September 2014

With the quickening of modern industrialization, the contradictions between environmental pollution and ecological cities are growing obvious,and the low carbon design of public facilities has become a widespread concern.On the basis of the analysis of the low carbon concept, its importance in the design of public facilities is put forward. Then the specific methods of low carbon design are discussed from some aspects, namely, the material selection, the structure design, recyclable products, the extension of product life, the use of new technologies and new energy.
Squeeze Flow of Thixotropic Semisolid Slurries
Authors: Alexandrou Andreas N. , Florides Georgios C. , Georgiou Georgios
Published: September 2014

An essential element for the integration of a semisolid process in the production of complex commercial components is the availability of accurate mathematical and computational tools that could describe both the rheological behavior and the material characteristics of the suspension, which are strongly affected from its internal structure and its evolution during deformation. In this study we considered the squeeze flow experiment, which is a standard method used to determine material properties of semisolid slurries, where a fixed amount of material is compressed from its topside either under constant load or constant velocity, while the bottom side remains fixed. Through high fidelity computational modeling we simulated the classical compression experiment by including the effects of thixotropy in order to demonstrate its role in determining material constants. More specifically a structural viscoplastic model based on the Bingham plastic constitutive equation is proposed. The yield stress is assumed to vary linearly with the structural parameter which follows a first-order rate equation accounting for the material structure break-down and build-up. The development of the yielded/unyielded regions in relation to material structural changes is analyzed. Furthermore, we performed also simulations, where the compression is interrupted for a short time, in order to study the material internal structure after a short relaxation time.
Semi-Solid Forging Process and Die Design in the Production of Aluminum Thin Plates
Authors: Jin Chul Kyu , Kang Chung Gil
Published: September 2014

In this study, A356 aluminum thin plates (1.2 mm thick) are fabricated using the semi-solid forming process. Using the electromagnetic stirrer, A356-based semi-solid slurry is fabricated. The configuration of the thin die cavity for forging is designed using the fluid analysis of MAGMA software. The dimension of the thin plate is 150 x 150 x 1.2 mm. The semi-solid slurry with 45% solid fraction is created and then injected into the forging die at the 200-ton hydraulic press for compression. Thin plate with semi-solid slurry at 45% of the solid fraction (fs) is fabricated with punch speed of 300 mm/s and punch pressure of 200 MPa for compression the slurry. The formability, mechanical properties and microstructure of a formed thin plate sample are analyzed. As a result, a thin plate with 211.5 MPa of tensile strength and 8.5% of elongation can be formed.
Semisolid Metals: A Suspension with Non-Newtonian Liquid Matrix
Authors: Modigell Michael , Harboe Siri , Pola Annalisa , Zang Christoph
Published: September 2014

The improvement of mathematical models for semisolid alloy flow properties requires profound understanding of the underlying physical nature. To date, it is commonly accepted that the shear thinning behaviour of these suspensions is caused by the solid phase microstructure, while the liquid phase is assumed to be Newtonian with a viscosity in the lowermPas-range. Recent measurements however, demonstrate non-Newtonian behaviour of fully liquid metals with pronounced shear thinning and high viscosities (multiplePas) in the low shear-rate range. By gathering and analysing rheological measurement data of various alloys (Sn14.2%Pb, A356 and X210CrW12), the relevance of the new findings for semisolid metals is investigated. The results indicate that the previously unexamined non-Newtonian flow behaviour of the liquid matrix has, besides the solid fraction, the most dominant influence on the shear thinning behaviour of semisolid alloys. The influences of shear-rate and solid fraction are nearly independent of each other which allow the construction of master-curves; a general flow curve for the suspension where the solid fraction is considered by a scaling factor. Consequently, a modelling approach is suggested in which the dependency of solid fraction is considered independently of the shear-rate.
The Research on the Annulus Electromagnetic Stirring for Preparing the Semisolid A356 Aluminum Alloy Slurry
Authors: Bai Yue Long , Xu Jun , Zhang Zhi Feng
Published: September 2014

The effects of annulus gap width, stirring power and stirring frequency on the microstructure of the semi-solid A356 aluminum alloy slurry have been investigated by the annulus electromagnetic stirring (AEMS) technology The results show that narrow annulus gap , strong stirring power and high stirring frequency are advantageous to obtain the small spherical primarymicrostructure, the smaller the annulus gap width is, the bigger the stirring power is, and the higher the stirring frequency is, the more uniform, the smaller and the more spherical the microstructure is. So the high stirring frequency, narrow annulus gap, strong stirring power are beneficial to obtain the fine and spherical semisolid microstructure in AEMS. Also the results indicate that the primary particles are globular, small and distribute homogeneously in the AEMS.
Anodising of Aluminium Alloy Plates from Different Series Produced by Rheo-High Pressure Die Casting
Authors: Chauke Levy , Möller Heinrich , Govender Gonasagren
Published: September 2014

Anodising of aluminium alloy components can be used for decorative purposes and to enhance the corrosion and wear resistance. In this research, four different Al-alloy series namely Al-Cu-Mg (2xx/2xxx), Al-Si-Mg (3xx), Al-Mg-Si (6xxx) and Al-Zn-Mg-Cu (7xxx) were used to produce plates by rheo-high pressure die casting (R-HPDC). Castings produced by R-HPDC suffer from a surface liquid segregation (SLS) phenomena. This surface layer is enriched with alloying elements and it is shown to have different characteristics as compared to the bulk material. The study focused on the anodisability of plates from the four series produced by R-HPDC with and without the SLS. The samples were anodised at a commercial facility. The oxide layer thickness and homogeneity were studied using optical microscopy.
The Solution Heat Treatment of Rheo-High Pressure Die Cast Al-Mg-Si-(Cu) 6xxx Series Alloys
Authors: Daswa Pfarelo , Möller Heinrich , du Toit Madeleine , Govender Gonasagren
Published: September 2014

The 6xxx series alloys are well known for desirable combinations of high strength, weldability, corrosion resistance and formability. This paper investigates the influence of chemical composition on the solution heat treatment parameters of rheo-high pressure die cast (R-HPDC) 6xxx series aluminium alloys. The presence of copper in the 6xxx series aluminium alloys affects the solution heat treatment by promoting incipient melting. The incidence of incipient melting is investigated for the R-HPDC alloys using Differential Scanning Calorimetry (DSC) and optical microscopy. R-HPDC is known to produce surface liquid segregation and centre-line liquid segregation when processing the alloys and these areas are the most susceptible to incipient melting. The applicability of single and multiple step solution heat treatments are investigated. The alloys used for this study include the Cu-free alloy 6082, as well as the Cu-containing alloys 6013 and 6111.
Continuous Production of a Multi-Filament Reinforced Metal Matrix Composite Strip from the Semisolid State
Authors: de Pádua Lima Filho Antonio , Ikeda Rafael Shoiti , de Castro Tales Paschoalino , Pugina Filho Ricardo Luiz
Published: September 2014

Continuous metal matrix composite strip casting (MMCS-ing) composed of six 0.3-mm diameter annealed bare copper wires in a eutectic SnPb matrix was manufactured by a two-roll melt dragged processing (TRMD-ing) method at a rate of 0.3 m/s. The wires were dragged through a semisolid pool with a fibre contact time of approximately 0.2 s. The required gap between rolls to thixoforge the semisolid material around the wire filaments was approximately 1.4 mm. A successful continuous composite strip casting was achieved with a notably good degree of wire alignment. No cracks were observed at the copper wire/matrix interface. However, regions of porosity occurred in the matrix; their possible formation mechanisms are discussed. The solidification structure of the matrix was analysed, and the analysis results indicated the formation of small globular grains measuring approximately 3 μm in diameter. The specimens were evaluated for their tensile properties and compared with the rule of mixtures. The surface fracture analysis indicated a good matrix/fibre union. MMCS-ing is an economically viable process and has significant advantages over other metal matrix composite (MMC) fabrication methods.
Influence of Process Parameters on Surface Appearance and Roughness of a Low Si Containing Al-Alloy, in Semisolid Casting
Authors: Jarfors Anders E.W. , Rigovacca Diego , Payandeh Mostafa , Wessen Magnus , Seifeddine Salem , Jansson Per
Published: September 2014

The visual appearance and surface roughness were experimentally investigated in industrial scale for a low silicon containing aluminium alloy cast in semisolid state integrated with HPDC machine. A visual comparative technique and surface roughness in the form of the Rq value were used to evaluate the surface appearance and the surface roughness respectively. The results were investigated statistically to find significant models. It was shown that high quality appearance, following a comparative scale, was possible using high die temperature and high injection speed. It was also found that improving the surface roughness will deteriorate the visual appearance.
Comparison of Microstructure and Mechanical Properties of Semi-Solid Castings Produced Using Billets Made by EMS and SEED
Authors: Liang Xiao Kang , Li Da Quan , Côté Pascal , Midson Stephen P. , Zhu Qiang
Published: September 2014

The spheroidal grains in billets used for semi-solid casting are generally manufactured by electromagnetic stirring (EMS) during the casting process. This method however, is not economically applicable for small quantities of the thixo billets. Swirled Enthalpy Equilibration Device (SEED) has been developed as a rheocasting process, and the SEED process is of interest for developing new thixo alloys, as well as for optimizing the thixocasting processes for high quality components. The objective of this paper is to compare the microstructure and mechanical properties of aluminum alloy 319s billets and castings produced using EMS and SEED feed materials. The experimental results show that for as-cast billets made from SEED process, a well-developed spheroidal grain structure is distributed throughout the cross-section of the billet, while for as-cast EMS billets, the grain structure is inhomogeneous, i.e., a dendritic structure was present adjacent to the surface of the billet, while a uniform, spheroidal structure was present at the centre. After the thixocasting process, however, the both SEED and EMS billets have well-developed, spheroidal grain structures. Mechanical properties of thixocast and T61 heat treated components are comparable for the both SEED and EMS billets.
Analysis of a Thixo-Lateral Forged Spindle from LTT C45, LTT C38 and LTT 100Cr6 Steel Grades
Authors: Lozares Jokin , Azpilgain Zigor , Hurtado Iñaki , Loizaga Iñigo
Published: September 2014

Due to the current trend in prices of raw material and their sources, near net shaping of mechanical components will become a key factor for the companies to get the desired competitiveness. Semisolid metal (SSM) forming is one of those near net shape forming techniques revealing a high potential to reduce material as well as energy consumption compared to conventional process technologies. Thus, the aim of this research work is to demonstrate the above by manufacturing a steel commercial automotive spindle by thixo-lateral forming from three different steel grades. The starting material, the microstructure and mechanical properties are analysed along the article. Material savings of 20% have been reported together with a substantial decrease of the forming forces. In addition, great mechanical properties have been achieved which brings the process closer to the desired final industrial application.
Effects of Inclined Plate Angle and Length on Semi-Solid Microstructure of Martensitic Stainless Steel
Authors: Song Ren Bo , Li Ya Ping , Wang Yong Jin , Wang Peng
Published: September 2014

An experimental equipment with inclined plate cooling and shearing had been developed to prepare semi-solid 9Cr18 martensitic stainless steel slurry. The effects of inclined plate angel and length on microstructures refinement and spheroidization in semi-solid 9Cr18 alloy was investigated. The results show that when the molten alloy is flowing along the plate surface, the microstructure of the alloy involves from coarse dendrite to fine spherical grains, the sloping plate can provide sufficiently the undercooling for nucleation and lay a foundation for heterogeneous nucleation to form lots of nuclei of crystal internally and on the sloping plate surface, thus causing the melt to nucleate eruptively. Sloping plate angle and sloping plate length can affect the shear strength and shear time of the flow alloy on the sloping plate and thus influence alloy microstructure. Fine spherical grain in the semi-solid 9Cr18 slurry can be obtained at α=45°and L=600mm, the major grain equivalent diameters are less than 55μm and more than 40% of the grain shape factor is in 0.75, exhibiting better grain fine degree and roundness. Using energy dispersive spectrometer (EDS) to investigate the liquid and solid phase in the 9Cr18 semi-solid slurry, iron content is lower and carbon and chromium content is higher in the liquid phase than in the solid phase which makes it possible to prepare the FGM (functional gradient material) with a high wear resistance in the surface and a good strength and toughness in the center.
Squeeze Casting of Semi-Solid A356 Alloy
Authors: Yang Xiang Jie , Wang Ming , Ding Liang Sheng , Guo Hong Min , Liu Xu Bo
Published: September 2014

the rheo-squeeze casting (Rheo-SQC) combining the rheocasting and the SQC was developed, in which semi-solid slurry was produced by the low superheat pouring with a shearing field (LSPSF) process. The three dimensional morphology of the primary α-Al phase and the rest spacing of slurry prepared by LSPSF process have been reconstructed and visualized, and the microstructures of squeeze cast A356 alloy have been obtained. Based on the three dimensional microstructure reconstructed, their three dimensional characterizations such as solid volume fraction, equivalent diameter of the extracted primary α-Al phase were measured and calculated, and the microstructures of cross section of squeeze cast product were investigated.
Effect of Casting Size on Microstructure and Mechanical Properties of Thixocastings
Authors: Lu Hong Xing , Zhu Qiang , He You Feng , Li Da Quan , Midson Stephen P.
Published: September 2014

A general rule in conventional liquid metal casting processes is that smaller size would produce better metallurgical quality and mechanical properties. The conclusion that semi-solid thixocasting process doesnt follow this rule has been made recently. The microstructure and mechanical properties of semi-solid thixocastings are much less dependent on casting size and cooling rate than the liquid castings. The step casting in the previous study is specially designed and simplified. The practical castings, e.g. turbocharger impellers, are more complex than the step castings. In this work, the turbocharger impeller is used to study the impact of section size representing the casting size on the microstructure and mechanical properties of semi-solid thixocastings, compared with the step casting. Section thickness decreases from 50 mm to 3.5 mm. In addition, the impact of casting thickness on the eutectic phase is also presented. The results reveal that the size of primary α-Al particles is insensitive to the casting thickness in semi-solid thixocasting. The cooling rate has a notable impact on the size and geometric characteristics of the eutectic silicon particles, but the impact is reduced by the following T61 heat treatment. The association between the casting thickness and casting defects is discussed, in order to further understand the impact of casting size on durability and reliability of real casting components.
Hypereutectic Al-Si Alloy Tube with Gradient Structure Produced by Rheo-Squeeze Casting
Authors: Zhou Rong , Li Lu , Jiang Ye Hua , Zhou Rong Feng , Wang Jia
Published: September 2014

In this paper, the wear property of a rheo-squeeze casting Al-22Si-2Fe-1.4Mn alloy tube was investigated. The semi-solid slurry of Al-22Si-2Fe-1.4Mn alloy was prepared using segmented cooling plates. The results showed that the volume fraction and equivalent diameter of the hard particles (primary silicon and blocky Fe-rich phases) increased gradually from the outside to the inside of the tube wall. The microstructures of the tube were examined with an optical microscope, scanning electron microscope, X-ray diffraction. The micro-hardness of hard particles and the macro-hardness from the outside to the inside of the wall were tested, respectively. Wear resistance tests of the outside and the inside of the wall showed wear resistance, which depends on the distribution and the volume fraction of the hard particles, increased gradually from the outside to the inside of the tube wall, changed in gradient and agreeing with the distribution law of macro-hardness.
Microstructural Evolution of Semi-Solid Type 304 Stainless Steel Deformed Severely by ECAP
Authors: Toofaninejad Mohsen , Nili-Ahmadabadi Mahmoud , Shirazi Hassan
Published: September 2014

Thixoforming or semi-solid metal forming offers many advantages in comparison with casting and conventional forging. However, due to the high-melting temperature and related difficulties, there is relatively a few experimental data on the semi-solid processing of steels. Therefore, this study is subjected to study the microstructure evolution during partial remelting of 304 stainless steel which is priorely deformed in solid state by equal channel angular pressing (ECAP) at room temperature. ECAP is a promising technique to induce a great homogeneous strain in bulk metals known as a new method for strain induced melt activation (SIMA) process for preparing thixoforming ingot. Simultaneously, the effect of number of passes during ECAP was also discussed in terms of the microstructure change. The results showed that the microstructure was well refined with formation of fine twins and partial martensite along with many fine equiaxed grains which in turn lead to fine and spheroidal semi-solid slurry. It can be confirmed that ECAP followed by reheating was an effective method to produce semi-solid ingot for thixoforming.
Helminth Infections Decrease Host Susceptibility to Immune-Mediated Diseases
Authors: Weinstock Joel V. , Elliott David E.
Published: September 2014

Helminthic infection has become rare in highly industrialized nations. Concurrent with the decline in helminthic infection has been an increase in the prevalence of inflammatory disease. Removal of helminths from our environment and their powerful effects on host immunity may have contributed to this increase. Several helminth species can abrogate disease in murine models of inflammatory bowel disease, type 1 diabetes, multiple sclerosis, and other conditions. Helminths evoke immune regulatory pathways often involving dendritic cells, regulatory T cells, and macrophages that help to control disease. Cytokines, such as IL-4, IL-10, and TGF-β, have a role. Notable is the helminthic modulatory effect on innate immunity, which impedes development of aberrant adaptive immunity. Investigators are identifying key helminth-derived immune modulatory molecules that may have therapeutic usefulness in the control of inflammatory disease.
Observations of the generation of eastward equatorial electric fields near dawn
Authors: Kelley M. C. , Rodrigues F. S. , Pfaff R. F. , Klenzing J.
Published: September 2014

Abstract. We report and discuss interesting observations of the variability of electric fields and ionospheric densities near sunrise in the equatorial ionosphere made by instruments onboard the Communications/Navigation Outage Forecasting System (C/NOFS) satellite over six consecutive orbits. Electric field measurements were made by the Vector Electric Field Instrument (VEFI), and ionospheric plasma densities were measured by Planar Langmuir Probe (PLP). The data were obtained on 17 June 2008, a period of solar minimum conditions. Deep depletions in the equatorial plasma density were observed just before sunrise on three orbits, for which one of these depletions was accompanied by a very large eastward electric field associated with the density depletion, as previously described by de La Beaujardière et al. (2009), Su et al. (2009) and Burke et al. (2009). The origin of this large eastward field (positive upward/meridional drift), which occurred when that component of the field is usually small and westward, is thought to be due to a large-scale Rayleigh–Taylor process. On three subsequent orbits, however, a distinctly different, second type of relationship between the electric field and plasma density near dawn was observed. Enhancements of the eastward electric field were also detected, one of them peaking around 3 mV m−1, but they were found to the east (later local time) of pre-dawn density perturbations. These observations represent sunrise enhancements of vertical drifts accompanied by eastward drifts such as those observed by the San Marco satellite (Aggson et al., 1995). Like the San Marco measurements, the enhancements occurred during winter solstice and low solar flux conditions in the Pacific longitude sector. While the evening equatorial ionosphere is believed to present the most dramatic examples of variability, our observations exemplify that the dawn sector can be highly variable as well.
Comparison of methods for modelling geomagnetically induced currents
Authors: Boteler D. H. , Pirjola R. J.
Published: September 2014

Abstract. Assessing the geomagnetic hazard to power systems requires reliable modelling of the geomagnetically induced currents (GIC) produced in the power network. This paper compares the Nodal Admittance Matrix method with the Lehtinen–Pirjola method and shows them to be mathematically equivalent. GIC calculation using the Nodal Admittance Matrix method involves three steps: (1) using the voltage sources in the lines representing the induced geoelectric field to calculate equivalent current sources and summing these to obtain the nodal current sources, (2) performing the inversion of the admittance matrix and multiplying by the nodal current sources to obtain the nodal voltages, (3) using the nodal voltages to determine the currents in the lines and in the ground connections. In the Lehtinen–Pirjola method, steps 2 and 3 of the Nodal Admittance Matrix calculation are combined into one matrix expression. This involves inversion of a more complicated matrix but yields the currents to ground directly from the nodal current sources. To calculate GIC in multiple voltage levels of a power system, it is necessary to model the connections between voltage levels, not just the transmission lines and ground connections considered in traditional GIC modelling. Where GIC flow to ground through both the high-voltage and low-voltage windings of a transformer, they share a common path through the substation grounding resistance. This has been modelled previously by including non-zero, off-diagonal elements in the earthing impedance matrix of the Lehtinen–Pirjola method. However, this situation is more easily handled in both the Nodal Admittance Matrix method and the Lehtinen–Pirjola method by introducing a node at the neutral point.
Generation of 2D Land Cover Maps for Urban Areas Using Decision Tree Classification
Authors: Höhle J.
Published: September 2014

Abstract. A 2D land cover map can automatically and efficiently be generated from high-resolution multispectral aerial images. First, a digital surface model is produced and each cell of the elevation model is then supplemented with attributes. A decision tree classification is applied to extract map objects like buildings, roads, grassland, trees, hedges, and walls from such an "intelligent" point cloud. The decision tree is derived from training areas which borders are digitized on top of a false-colour orthoimage. The produced 2D land cover map with six classes is then subsequently refined by using image analysis techniques. The proposed methodology is described step by step. The classification, assessment, and refinement is carried out by the open source software "R"; the generation of the dense and accurate digital surface model by the "Match-T DSM" program of the Trimble Company. A practical example of a 2D land cover map generation is carried out. Images of a multispectral medium-format aerial camera covering an urban area in Switzerland are used. The assessment of the produced land cover map is based on class-wise stratified sampling where reference values of samples are determined by means of stereo-observations of false-colour stereopairs. The stratified statistical assessment of the produced land cover map with six classes and based on 91 points per class reveals a high thematic accuracy for classes "building" (99 %, 95 % CI: 95 %-100 %) and "road and parking lot" (90 %, 95 % CI: 83 %-95 %). Some other accuracy measures (overall accuracy, kappa value) and their 95 % confidence intervals are derived as well. The proposed methodology has a high potential for automation and fast processing and may be applied to other scenes and sensors.
Effective leaf area index retrieving from terrestrial point cloud data: coupling computational geometry application and Gaussian mixture model clustering
Authors: Jin S. , Tamura M. , Susaki J.
Published: September 2014

Abstract. Leaf area index (LAI) is one of the most important structural parameters of forestry studies which manifests the ability of the green vegetation interacted with the solar illumination. Classic understanding about LAI is to consider the green canopy as integration of horizontal leaf layers. Since multi-angle remote sensing technique developed, LAI obliged to be deliberated according to the observation geometry. Effective LAI could formulate the leaf-light interaction virtually and precisely. To retrieve the LAI/effective LAI from remotely sensed data therefore becomes a challenge during the past decades. Laser scanning technique can provide accurate surface echoed coordinates with densely scanned intervals. To utilize the density based statistical algorithm for analyzing the voluminous amount of the 3-D points data is one of the subjects of the laser scanning applications. Computational geometry also provides some mature applications for point cloud data (PCD) processing and analysing. In this paper, authors investigated the feasibility of a new application for retrieving the effective LAI of an isolated broad leaf tree. Simplified curvature was calculated for each point in order to remove those non-photosynthetic tissues. Then PCD were discretized into voxel, and clustered by using Gaussian mixture model. Subsequently the area of each cluster was calculated by employing the computational geometry applications. In order to validate our application, we chose an indoor plant to estimate the leaf area, the correlation coefficient between calculation and measurement was 98.28 %. We finally calculated the effective LAI of the tree with 6 × 6 assumed observation directions.