bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantum-Behaved Particle Swarm Optimization Based Radial Basis Function Network for Classification of Clinical Datasets
Authors: Leema N. , Nehemiah H. Khanna , Kannan A.
Published: February 2018

In this article, a classification framework that uses quantum-behaved particle swarm optimization neural network (QPSONN) classifiers for diagnosing a disease is discussed. The neural network used for classification is radial basis function neural network (RBFNN). For training the RBFNN K-means clustering algorithm and quantum-behaved particle swarm optimization (QPSO) algorithm has been used. The K-means clustering algorithm is used to find the optimal number of clusters which determines the number of neurons in the hidden layer. The cluster approximation error is used to find the optimal clusters. The weights between the hidden and the output layer is determined using QPSO algorithm based on the mean squared error (MSE). The performance of the developed classifier model has been tested with five clinical datasets, namely Pima Indian Diabetes, Hepatitis, Bupa Liver Disease, Wisconsin Breast Cancer and Cleveland Heart Disease were obtained from the University of California, Irvine (UCI) machine learning repository.
Application of Buckling-Restrained Braces in the Seismic Design of a Thermal Power Plant in China
Authors: Aguaguiña Mario , Zhou Ying , Gong Shun Ming , Fang Zhi Qing
Published: February 2018

This paper presents the use of buckling-restrained braces (BRBs) in the design of the main building of a thermal power plant as an alternative for the construction of such kind of large industrial facilities. The project is located in Suqian, Jiangsu Province, a region of high seismic demand (Intensity 8) in China. The main lateral force resisting system used for the structure of this project is composed of a combination of conventional concentrically braced frames (CBFs) and buckling-restrained braced frames (BRBFs). The paper explores the seismic design and performance assessment of this industrial steel building according to the provisions of the Chinese code. Response spectrum analysis and time-history analysis were conducted under two levels of seismic hazard: minor earthquake (63.2%/50 years) and major earthquake (2%/50 years). Results indicate that BRBs effectively helped to control lateral deformation and dissipated energy in stable manner, making the structure composed of CBFs and BRBFs to show the seismic performance as intended by the code.
Comments about the Seismic Behavior of “Inverted Y”- Braced Frames
Authors: Köber Helmuth , Stoian Marina
Published: February 2018

Four configurations were analyzed for a ten storey “inverted Y-braced” frame with rigid and/or pined beam/column and diagonal/column connections. All considered frame configurations were sized for the forces produced by the same code seismic design force evaluated according to the in charge Romanian seismic design code. In case of two of the considered configurations, additional potentially plastic zones with reduced member cross-sections were provided along the girders and diagonals of the frame (in order to size clearly by design a global plastic failure mechanism for the “inverted Y-braced” frame). The behavior of each frame configuration during dynamic nonlinear analyses was observed. The steel consumption was estimated for each considered configuration.
Multi-Hazard Risk Mitigation through Application of Seismic Design Rules
Authors: Dubină Dan , Dinu Florea , Marginean Ioan
Published: February 2018

Multi-story buildings often use steel moment frames as lateral force resisting systems, because such systems would allow architectural flexibility, while providing the strength, stiffness, and ductility required to resist the gravity, wind, and seismic loads. Steel moment frames on which capacity design concepts are applied to resist earthquake induced forces, are generally considered robust structures, with adequate resistance against collapse for other extreme hazards, for example blast or impact. Starting from this point, the present paper summarizes the results of some recent studies carried out in the Department of Steel Structures and Structural Mechanics and CEMSIG Research Center from Politehnica University Timisoara, aiming to evaluate the influence of beam-to-column joints, designed to satisfy seismic design requirements, on the progressive collapse resistance of multi-story steel frame buildings.
Seismic and Robustness Design of Steel Frame Buildings
Authors: Ferraioli Massimiliano , Lavino Angelo , Mandara Alberto , Donciglio Marianna , Formisano Antonio
Published: February 2018

In this paper, a design procedure that combines both progressive collapse design under column removal scenario and capacity design to produce a hierarchy of design strengths is presented. The procedure develops in the context of the European Standards, using the classification of European steel sections and considering the seismic design features. Three-dimensional models of typical multi-storey steel frame buildings are employed in numerical analysis. The design for progressive collapse is carried out with three types of analysis, namely linear static, nonlinear static and nonlinear dynamic. Since the behaviour following sudden column loss is likely to be inelastic and possibly implicate catenary effects, both geometric and material nonlinearities are considered. The influence of the fundamental parameters involved in seismic and robustness design is finally investigated.
Identifying Critical Connections for the Global Performance of Steel Moment Resisting Frames
Authors: Steneker Paul , Wiebe Lydell D.A. , Filiatrault Andre
Published: February 2018

The investigations following the unacceptable performance of moment resisting frames (MRFs) in the 1994 Northridge Earthquake led to the development of a variety of alternative ductile connections. Tests have shown that these connections have reliable component-level performance, leading to them being recommended in standards worldwide as pre-qualified for MRFs. Current design practice consists of applying a single type of ductile connection, often the reduced beam section (RBS), uniformly throughout an entire frame. These connections are detailed and inspected to ensure that each connection has a similar minimum deformation capacity throughout the building, regardless of local deformation demands.This paper examines the potential design implications of identifying local areas within a MRF having the greatest joint rotational demands. Once identified, the connections at these locations are deemed critical to the global performance of the frame. First, the collapse analysis of a six-storey MRF with well-detailed RBS connections was conducted to quantify an upper bound system-level performance. Thereafter, a lower bound system-level performance was determined by considering a frame constructed using only connections with a lowered rotational capacity. Subsequent series of analyses were conducted to identify critical locations within the frame where RBS connections must have a high reliable rotational capacity to ensure adequate system-level performance.
Portal Frames with a Novel Cold-Formed Tapered Box-Section
Authors: Shahmohammadi Amir , Lim James B.P. , Clifton George Charles
Published: February 2018

This paper introduces a novel steel portal frame system, in which cold-formed nested tapered box members are used in the design. The bird and dust proofing features of the system make it useful for applications where clean work areas are required, such as food, storage, and manufacturing industries. The new section used in the portal frames comprises two cold-formed channels welded to each other, forming a box-shaped steel member, either tapered or prismatic along its length. Such sections possess high torsional stiffness compared with the conventional I-sections; therefore, lateral bracing employed for the flexural-torsional buckling suppression of I section portal frames is mostly unnecessary. A comparative study, taking into account the cost of steel, painting, bird proofing and lateral bracing, is conducted between a number of portal frames with the proposed box-sections and the conventional I-sections. An analysis and design code, incorporating the Genetic Algorithm (GA), is developed to optimise the weight of the designed frames. The results indicate that the novel portal frame system is economically viable with additional benefits of bird and dust proofing. To investigate the failure modes and verify design procedure of the new portal frame, an experimental testing program is undertaken in University of Auckland. The test results show excellent behaviour and good agreement with the numerical models but have been completed too recently to be included in this paper.
Capacity Design Criteria of 3D Steel Lattice Beams for Applications into Cultural Heritage Constructions and Archaeological Sites
Authors: Formisano Antonio , di Lorenzo Gianmaria , Babilio Enrico , Landolfo Raffaele
Published: February 2018

Three-dimensional lattice beams are highly efficient technical solutions to cover large spans, especially when the single members do not have intermediate restraints able to prevent lateral-torsional buckling phenomena. Hence, lattice structures are widely applied in any field of civil and industrial engineering. In the present paper, in the framework of a research project funded by both the Campania Region and the European Community, a compound structure made of welded lattice beams and structural glass slabs is proposed as a structural system for valorisation and protection of monumental constructions and archaeological sites. Due to both the risk exposure of monumental heritage to be protected and the use of structural glass, the definition of an appropriate design criterion is mandatory in order to avoid development of brittle collapse mechanisms, mainly under static and dynamic vertical loads. The attention is herein paid to the design procedure, with a brief description of basic ideas behind the project itself and the main focus on the parametric capacity design of structural members. The proposed procedure, whose validity is quite general, has been subsequently verified by linear and non-linear numerical analyses calibrated on the basis of experimental investigations carried out on both the beam material and full-scale beam prototypes.
Shake Table Testing of a Low Damage Steel Building with 2-4 Displacement Dependent (D3) Viscous Damper
Authors: Hazaveh Nikoo K. , Rad Ali A. , Rodgers Geoffrey W. , Chase J. Geoffrey , Pampanin Stefano , Ma Quincy T.
Published: February 2018

To improve seismic structural performance, supplemental damping devices can be incorporated to absorb seismic response energy. The viscous fluid damper is a well-known solution. However, while they reduce displacement demand, they can increase overall base shear demand in nonlinear structures as they provide resistive forces in all four quadrants of force-displacement response. In contrast, Direction and Displacement Dependent (D3) viscous fluid dampers offer the opportunity to simultaneously reduce structural displacements and the total base-shear force as they only produce resistive forces in the second and fourth quadrants of a structural hysteresis plot. The research experimentally examines the response of a half-scale, 2-storey moment frame steel structure fitted with a 2-4 configuration D3 viscous fluid damper. The structure is also tested with conventional viscous dampers to establish a baseline response and enable comparison of results. Dynamic experimental tests are used to assesses the base shear, maximum drift and residual deformation under 5 different earthquakes (Northridge, Kobe, Christchurch (CCCC), Christchurch (CHHC), and Bam ground motion). Response metrics including base shear, the maximum structural displacement, and peak structural accelerations are used to quantify performance and to assess the response reductions achieved through the addition of dampers. It is concluded that only the 2-4 device is capable of providing concurrent reductions in all three of these structural response metrics.
Shake Table Testing of Steel Braced Frame Considering Member Fracture
Authors: Terazawa Yuki , Matsui Ryota , Takeuchi Toru
Published: February 2018

Fracture of concentric braced frames due to local buckling under cyclic loading often requires computationally intensive 3D shell models. For practical design, the authors have previously proposed a phenomenological stick model that accurately captures local fracture, referred to as the Direct Local Strain Evaluation Method. However, the accuracy of the proposed method has previously only been validated using quasi-static cyclic component tests. This research extends this work, validating the method under dynamic loading conditions using numerical studies and in-frame shake table testing. The method is shown to be in good agreement with the global response and to accurately capture fracture due to local buckling under cyclic dynamic loads.
Contribution of Beam-Column Connections with Bolted Angles in the Reserve Capacity and Full-Scale Cyclic Testing
Authors: Béland Thierry , Tremblay Robert , Sizemore Joshua , Fahnestock Larry A. , Bradley Cameron , Hines Eric
Published: February 2018

Partially restrained beam-column connections can be used in the gravity load system of building structures to develop moment frame action to enhance collapse prevention for low-ductility steel lateral systems. The benefit from such reserve lateral strength and stiffness is illustrated for a low-rise building with steel braced frames designed in accordance with Canadian provisions for seismic force resisting systems of the Conventional Construction category. Preliminary results from a comprehensive cyclic test program recently completed on beam-to-column joints with bolted double web angle acting with top and seat angles are presented. The test program included 23 full-scale beam-to-column sub-assemblages subjected to combined gravity shear forces and cyclic rotational demands. Experimental observations on the deformation patterns and failure modes are presented together with representative hysteretic moment-rotation responses of bolted double web angles without and with top and seat angles.
Finite Element Analysis on K-Type External Braced Steel Frame System
Authors: Li Guo Chang , Tian Fei , Yang Zhi Jian , Zhang Guo Zhong
Published: February 2018

The concept of moment resisting frames with K-type external braces is proposed to increase the lateral stiffness, which has short external span and large lateral stiffness. In order to investigate the lateral stiffness, overstrength coefficient and the reduction factor of K-type external brace under horizontal load, ABAQUS was applied to study the different slenderness ratios (from50 to 150) of K-type external steel braced frames. The results showed that the lateral load and displacement curve can be divided into elastic stage, the buckling of the compressive brace-yield of the tensile brace stage and plastic stage. The overstrength of K-bracing is related to the potential bearing capacity of the frame when the compressive brace buckled, and the potential growth of the tensile brace. The overstrength coefficient increases with increasing of the brace slenderness ratio. The range of recommended values of slenderness ratios of K-type external steel braces and design values of unbalanced force of column sections are proposed.
Cyclic Performance of a Lightweight Rapidly Constructible and Reconfigurable Modular Steel Floor Diaphragm
Authors: Boadi-Danquah Eugene , MacLachlan Duncan , Fadden Matthew
Published: February 2018

One approach to making modern structures more economically and environmentally sustainable is designing and constructing them to be adaptable to rapidly changing markets and building occupancies. At the same time, these structures are required to be resilient to seismic events. As a step towards meeting these goals, a lightweight, two-way, rapidly constructible and reconfigurable modular steel floor (RCRMSF) system has been developed. The system is fabricated from light-gauge steel plates sandwiching a grillage of orthogonally arranged cold formed Z-purlins, can span 9.1 m x 12.2 m, requires only girder supports, and fits within current steel construction framework. This study investigates the seismic behavior of the RCRMSF diaphragm through the use of high fidelity nonlinear finite element (FE) models. Six full-scale cantilever diaphragm models have been developed to study the effect of varying RCRMSF configurations and end support details. Both monotonic and cyclic loading protocols are used to determine the stiffness, strength, energy dissipation capacity, and general hysteretic behavior of the diaphragms. Based on the FE models, the behavior of the RCRMSF diaphragm is influenced primarily by the plate thickness and perimeter connection detail to the supporting steel frame. Overall, the RCRMSF has adequate diaphragm stiffness and strength, and shows favorable energy dissipation capacity due to its post-peak inelastic behavior. This observation implies that the RCRMSF can serve as an alternative solution to current seismic design and construction practices.
Numerical Study on Concentric Braced X Frames under Monotonic and Cyclic Loads
Authors: Faggiano Beatrice , Formisano Antonio , Vaiano Generoso , Mazzolani Federico M.
Published: February 2018

Concentric Braced Frames (CBF) are designed for dissipating the seismic energy mainly through plastic deformations of diagonals in tension, while beams and columns, designed on the basis of the hierarchy resistance criterion, should resist the design loads in elastic field without undergoing buckling and yielding phenomena. For such structural systems there are still some uncertainties on the performances under cyclic loadings, due to the degradation of the strength and stiffness under tension for the occurrence of instability problems in compression. The current paper deepens such key issues, presenting the numerical simulation of some literature experimental tests conducted on CBX frames subjected to monotonic and cyclic loads both in presence and in absence of vertical loads. The refined FE structural models of the study systems are developed through the software ABAQUS v6.13-1. The models set up have provided a very good replication of both monotonic and hysteretic behaviours in terms of strength, stiffness, ductility and energy dissipation. They are powerful analysis instruments to perform parametric studies, aiming at detecting the main factors affecting the cyclic structural behaviour, thus leading towards appropriate design criteria.
A Proof-of-Concept Study on Self-Centering Column Feet Equipped with Innovative Shape Memory Alloy Ring Springs
Authors: Fang Cheng , Wang Wei , Yang Xiao
Published: February 2018

This paper presents a feasibility study on a self-centering steel column foot equipped with innovative shape memory alloy (SMA) ring springs. The ring spring system includes a series of SMA outer rings and high-strength alloy inner rings stacked in alternation with mating taper faces, and the system is used in conjunction with high-strength bolts in a typical extended end-plate connection to achieve favorable self-centering and energy dissipation performances while ensuring ease of construction. An experimental investigation was first conducted looking into the basic mechanical performance of individual SMA ring springs under cyclic loading. Driven by the superelastic behavior of SMA, excellent self-centering ability with satisfactory energy dissipation is exhibited. Subsequently, a further experimental study on a proof-of-concept column foot specimen is conducted, where the key properties, including ductility, self-centering ability, and energy dissipation capability, are discussed in detail in this paper.
Seismic Collapse Analysis of Steel Plate Shear Wall Systems
Authors: Verma Abhishek , Sahoo Dipti Ranjan
Published: February 2018

Steel Plate Shear Walls (SPSWs) have proven to be efficient lateral force-resisting systems. SPSWs utilize the post-yielding strength of the unstiffened web plates, which makes the system economically viable. ANSI/AISC 341-10 suggests the value of response modification factor for SPSWs to be 7, which is based on judgment and qualitative comparisons with response capabilities of previously well-studied systems. This study is focused on the evaluation of the seismic performance factors for SPSW systems through the collapse analysis in accordance with FEMA P695 recommendations. Three-and six-story SPSWs are considered in the study. Aspect ratio of the web plates is varied to obtain the archetypes. Numerical models of the study frames are developed and analyzed using a computer softwareOpenSees. The modelling technique is validated by comparing the predicted hysteretic response with the past experimental results. Both nonlinear static and dynamic analyses are conducted for the study frames. The results of the collapse analysis are presented and the values of seismic performance factors given in ANSI/AISC 341-10 are verified. Collapse mechanisms of the models for each ground motion are identified and a probability analysis is carried out to identify the most probable mechanisms. Further, suggestions are provided to avoid unnecessary over-strengthening and to ensure adequate collapse margin ratio.
Multi-Mode Pushover Procedure to Estimate Higher Modes Effects on Seismic Inelastic Response of Steel Moment-Resisting Frames
Authors: Ferraioli Massimiliano , Lavino Angelo , Mandara Alberto
Published: February 2018

The paper deals with a multi-mode pushover procedure that considers higher mode effects, frequency content of response spectra as well as nonlinear interaction between modes. Pushover analyses are conducted with story-specific generalized force vectors. Each force vector is calculated through modal analysis and builds up the instantaneous distribution of forces acting on the structure when the interstory drift at each story attains its maximum value during the seismic motion. In order to improve the computational cost effectiveness, both mode truncation and limitation in the number of generalized pushovers are used by checking, however, the accuracy in the evaluation of the interstory drifts at all levels. The target interstory drift is calculated through three different modal combination procedures.
Buckling Restrained Brace Deformation Measuring Device
Authors: Telford Joshua W. , Sim Ashley W. , MacRae Gregory A. , Clucas Don M.
Published: February 2018

Buckling Restrained Braces (BRB’s) have become common in seismic frames in earthquake areas. If a BRB performs as desired the steel core may yield but it is not easy to know the degree of yielding, or how much of the BRB earthquake life has been used up. To determine whether such a brace should remain as is, or whether it needs to be replaced, an inexpensive and simple measuring device that reports the deformations undergone is required. This paper discusses a study undertaken to develop such a device. Firstly, a literature study was undertaken and candidate devices were selected. Using Subjective Quantitative Analysis (SQA) and specific performance objectives the most appropriate of these was chosen. This device was then constructed and tested in a controlled environment. This mechanical device performed well through various stimulated earthquake cycles and events, is cheap, simple to install, and small. It provides cumulative and maximum displacement estimations and will be beneficial to the industry in post-event decision making.
Magnetorheological Fluid with Nano Fe3O4 for Performance Enhancement of MR Damper for Seismic Resistance of Steel Structures
Authors: Daniel C. , Hemalatha G. , Sarala L. , Tensing D. , Sundar Manoharan S.
Published: February 2018

Magnetorheological damper (MR damper) is one of the promising vibration control systems, applicable for damping seismic induced vibrations in structures, because of their ability to be controlled and to adapt their mechanical properties by varying the magnetic field, their high damping force, their low energy input required and their simple use. This paper presents the experimental results carried out to study the use of Nano Fe3O4as component of MR fluid. The Nano Fe3O4particles are obtained by an indigenous process to convert a waste product of chemical industry. The performance of Nano Fe3O4MR fluid is compared with five commercially available samples in the market namely, Mill scale, cast iron (1), cast iron (2), carbonyl iron and white iron oxide. Surface morphology was identified using SEM & the average particle size was analysed using XRD. Viscosity & settling measurements were also performed for all the six samples. Shake table tests were conducted to study the performance of steel frame with MR damper. The model for the study was a single bay three storey steel frame where the response of the structure, in terms of acceleration, velocity and displacement was observed. It was observed that the percentage of reduction in displacement, velocity, acceleration, approximately 40 – 67% for structure with MR damper.
Research on Electronic Discharge Grinding of Polycrystalline Diamond Based on Response Surface Method
Authors: Tang Jia Jun , Zhang Hui , Ye Pei Qing , Wang Chao Hai
Published: February 2018

To improve the material removal rate (MRR), the effects of electrode rotational speed, gap voltage and pulse width on the MRR of PCD EDM grinding process were studied. By adding pre-experiments, the optimization process is more rapid. A second-order regression model of MRR is established by using response surface method based on Composite Circumscribed design (CCC). And the influence of each parameter on the response is analyzed. The results show that the optimal removal rate is after optimized, which is 11.8% higher than that of the pre-experiment.
Fabrication and EDM Corrosion Resistance of Copper Electroforming Layer on Tube Electrode for Aero-Engine Blade Cooling Hole in EDM Process
Authors: Li Zhi Yong , Cui Qing Wei , Chen Bin , Xu Ji , Guo Hun
Published: February 2018

The process parameters of fundamental electroforming solution were optimized firstly. Furthermore, some pure copper electroforming samples were prepared in the condition of different nana La2O3 addition quantity. Three main material properties evaluated. In addition, the EDM machining experiments were conducted to verify the characteristics of electrical corrosion resistance resulting from the prepared copper tube electroforming samples for cooling hole of Inconel718 nickel alloy. EDM experimental results demonstrate that copper electroforming layer with grain size 15.9μm, microhardness 98.2HV, with 1.2g/L addition quantity of nana La2O3, and its electrode loss rate decrease 13.29% and 7.26% than pure copper and copper electroforming layer without nana La2O3 addition respectively.
Research on Milling Deformation in Ultrasonic Vibration Assisted End Milling of Titanium Alloy Thin-Walled Parts
Authors: Jiao Feng , Zhao Li , Yao Cheng Lin , Qi Feng
Published: February 2018

The hard machinability of titanium alloy material and the poor stiffness of thin-walled parts hindered the extensive application of titanium alloy thin-walled components in aerospace engineering. In order to heighten the geometric accuracy in the processing, the ultrasonic vibration assisted (UVA) end milling technology with workpiece vibrating in feed direction was put forward in this paper, and characteristics of the milling deformation in UVA milling of titanium alloy TC4 thin-walled workpieces were researched. Through the theoretical analysis, the cutting force and deformation characteristics in UVA milling were clarified. Based on the range analysis of orthogonal experiment, the effects of milling parameters and ultrasonic amplitude on the deflection displacement and the milling deformation of workpieces are obtained. Research results show that the deflection displacement in the process of UVA milling affects the thickness error of the thin wall. Ultrasonic parameters as well as milling parameters should be optimized to obtain higher machining accuracy. The research provides a certain reference for the precision milling of titanium alloy thin-walled parts.
The Roll-Forming Process Analysis of the Situation and Development Trend
Authors: Hu Miao , Li Yan Bo , Li Xin , Cao Xiao Lin , Hou Min
Published: February 2018

Roll – forming is through the allocation of roll the sheets for multiple successive of transverse bending deformation process of the section, to form a specific shape with high energy efficiency, uniform cross section, stable product quality, etc. Since the 19th century began to study the roll-forming process, successively completed the exploration of this kind of technology and promotion from 1938 to 1938.It has entered the rapid development of roll-forming technology at present. Began to roll-forming technology research relatively late in our country, but the trend of development of fast, such as the construction industry, automotive industry, white home appliance industry has been widely used, to specific parts such as highway anti-collision WeiDang, auto parts anticollision beam beams, before and after the threshold of the anticollision beam and a side door production, etc.
Roll-forming technology belongs to the nonlinear problem of large plastic deformation, the forming theory of the present domestic scholars have researched, forming a simplified analytical method, energy analysis method, cable original research method and finite element method theory. With the development of computer aided design technology, through the computer simulation of sheet deformation and regional stress analysis, and makes the product design cycle is shortened, the product design quality was improved.
At home and abroad, roll-forming equipment have developed highly efficient, the formation of the uncoiled stamping - roll-forming - welding - material such as plastic - cut – code craft route, eventually forming the results approach to the product shape, implementation process highly integrated production mode, cold-formed molding equipment of high automation intelligent design, help to realize planning of ‘Made in China 2025 strategy’ in the industry of roll-forming.
Research on the Effect of Cutter Position Points Distribution Optimization on Surface Milling Accuracy
Authors: Li Jie , Li Hong Bin , Zhang Hai Tao , Zhang Pan
Published: February 2018

The research analyzed the distribution of cutter position point data outputted by software CAM, based on the precision of surface milling. The model of the tool-path is established by using the piece-wise interpolation function, combining with the distribution characteristic of cutter position point. The segmentation optimization of the tool-path is also realized via the limitation and judgment of the string high error of the segmented trajectory and the optimization algorithm is integrated into the post-processing to improve the precision of the surface milling. The experiment results of surface milling show a positive effect of cutter position point optimization on surface milling accuracy.
Study on Parameter Optimization and Tool Wear of Milling Compacted Graphite Iron RuT450 Cylinder Block
Authors: Chen L. , Liu L. , Guo H. , Li C.W. , Yang X.K. , Wang Y.G.
Published: February 2018

In order to study the milling process of compacted graphite iron cylinder block in practical, cutting parameters optimization experiment was conducted when cutting parameters were set as independent variable, and cutting efficiency and spindle power were set as optimization objective. The results showed that spindle power increased as the cutting speed and feed per tooth increasing, but cutting torque increased initially and then decreased as the cutting speed increasing. Feed force decreased with the increasing cutting speed and decreasing feed per teeth. Matlab software was used to optimize the cutting parameters when cutting efficiency and empirical formula of spindle power were settled as the objective functions. The most suitable parameters were abtained as V=164m/min and fz=0.28mm/z. The tool rake face mainly took place crater wear and material sticking. The main wear mechanisms for rake wear and fland wear were abrasive wear and adhesion wear.
Study on High-Frequency Fatigue Properties of PVD AlTiN Coating of Cutting Tool
Authors: Wang N.C. , Liu Qing Feng , Cheng Xin , Jiang Feng
Published: February 2018

Based on ultrasonic vibration-assisted mode, high-frequency impacting tests with diamond indenter at different amplitudes on AlTiN coating of cutting tool are carried out. The microstructure and morphology are obtained by scanning electron microscopy (SEM) and 3D profiler. The failure mechanism of coating under impact is analyzed. The high frequency fatigue property of the coating is analyzed. The results show that: lateral crack could be seen under impact test; the maximum tensile stress occurs close the edge of the contact zone of impact center; AlTiN coating is easy to emerge the fatigue damage under the high-frequency impact loading, and the adhesion strength of the coating and substrate interface affects the impact fatigue strength of cutting tool coating.
Research on GC Cup Truing Technology of Super-Hard Grinding Wheel
Authors: Yao Zhu Xian , Xu Ji Miao , Zhang Lu
Published: February 2018

In this paper, the GC cup truing technology on resin bond diamond grinding wheel is studied, and the parameters of truing the diamond grinding wheel process are optimized. Also the contour accuracy and microscopic topography of the diamond grinding wheel are analyzed quantitatively. Besides, the method of evaluating the dressing effect of diamond grinding with the roughness of grinding wheel is proposed.
The Influence of Surface Welding Using EDTCrMnSi Special Wire on the Wear Resistance of 16Mn Steel
Authors: Wang Hong Xiang , Li Xiao Xiao , Ying Peng Zhan , Yin Hong Mei
Published: February 2018

Coal-winning machine is to break coal with rotating mechanism. Owing to the harsh working environment and large stress, the top-disc plate, helical blade and tooth holder in cylinder often lose their wear resistance, hence causing overhauling of the machine and influencing the production of coal. With the modernization of the production technology and mining equipment of coal, the mining intensity of coal constantly increases, which calls for higher wear resistance of the top-disc plate, helical blade and tooth holder in cylinder. Currently, many studies have been performed on the wear resistance of the tooth holder in cylinder, but rare on the wear-resistant technology and wear resistance of the top-disc plate and helical blade in cylinder. In this paper, 16Mn steel which is used in the top-disc plate and helical blade in the cylinder of coal-winning machine was welded based on surfacing technology using EDTCrMnSi special wire to obtain composite wear-resistant steel plates. Then wear tester was employed to compare the wear of 16Mn steel and composite wear-resistant steel plate. Meanwhile, metallographic microscope and x-ray fluorescence spectrometer (XRF) were used to observe the microstructure of the materials and analyze the types and contents of elements in the surfacing layers of the composite wear-resistant steel plate. Furthermore, the influence of surfacing technology on the wear resistance of the material was analyzed. The results showed that there existed high contents of Cr, Si and Mn in the surfacing layers of the top-disc plate and helical blade in cylinder of the coal-winning machine after welded based on surfacing technology. Moreover, the wear resistance and service life of matrix were largely improved.
Research on Friction Property of Pin on Disc and Analysis of Wear Mechanism Based on MMW-1A Friction and Wear Testing Machine
Authors: Chen Zhi Peng , Jin Xiao Yi , Ji Chun Yun , Wang Chuan , Zhu Jian Liu
Published: February 2018

Friction and wear are very important in mechanical design. This paper studies the friction and wear characteristics of 45 steel under oil lubrication. The sliding friction and wear experiment was carried out with the pin plate friction pairs on the MMW-1A friction and wear test machine. Researching the influence of velocity on friction factor under the same load, the relation between wear and load and wear analysis under the same speed different loads. The results showed that under the same load and with the increase of velocity, the friction factor had a gradually decreasing trend. When some of the parameters were certain, the wear volume and the loading force was roughly linear relation. Pitting occurred when the load increased.
A practical logMAR near reference table for low vision practitioners: Design and applicationd
Authors: Oduntan Alabi O.
Published: February 2018

LogMAR charts are particularly useful for visual acuity (VA) measurement for low visionpatients as they simplify conversion of non-standard viewing distance visual acuities to standard values. Also, the process of predictingvarious quantities involved in the prescription of optical devices for patients are greatly facilitated.  However, the processes involved in the use of this logMAR principle require series of multiplication and division by the logMAR ratio of 1.2589.  A table computed and presented in this article provides easy reference forthe conversions and predictions needed for the various quantities at near.  The table (Table 1) is computed using the logMAR scale of 1.2589in logMAR, M and N notations. The table contains VA values between logMAR 1.4 (10M or 80 point) and logMAR 0.18 (1.3M or10 point) in steps of 1.2589 for reduced (non-standard) viewing distances  ranging from 31.8 cm (0.32 m) to 3.2 cm (0.03M).  The table contains values which can be used to convert visual acuity values measured at reduced near viewing distances to standard visual acuity values.  The values also can be used to represent any of the quantities involved in the prescription of optical devices for low vision patients. The use of the table for converting reduced distance VA values to standard values and for predicting optical powers and visual performance of low vision patients are discussed with relevant examples. Like all principles based on the logMAR principles, the table is quite versatile in VA conversion and prediction of the various quantities such as print size that can be read by the low vision patient when factors such as viewing distance  or power are varied.
Antistigmatic accommodation
Authors: Gillan W. D. H.
Published: February 2018

No abstract available
Keratoconus: a research and clinical symposuim
Authors: Gillan W. D. H.
Published: February 2018

No abstract available
Zending en imperialisme in Zuid-Afrika
Authors: De Jongh C.
Published: February 2018

Evenals het Westerse imperialisme en kolonialisme is na Wereld- oorlog II de Christelijke zending onder schot genomen. Deze zending wordt door anti-Westerse en antikapitalistische stromingen als hand- langer van Westers imperialisme beschouwd. Onder meer in Noor- wegen hebben zendingsvrienden zich dat verwijt aangetrokken. Dit vroeger arms land is een der eerste en ijverigste zendingslanden in Europa. De Noorse zending heeft pionierswerk in Natal verricht en ik meen, dat haar betekenis in Zuid-Afrika eerder onder- dan overschat wordt, wegens gebrek aan kennis van de Skandinavische talen en bronnen.
Integrating different forms of knowledge
Authors: Rousseau Nici
Published: February 2018

From a view of multiple types of knowledge for a blend in teacher education, the paperdiscusses the need for epistemological diversity in the types of knowledge for grade Rteacher education. I claim in this article that for epistemological diversity, innovativemixes of knowledge are required and that they have to be explicated. The argument of thearticle is that the decisions made by teacher educators when constructing a curriculumfor a new grade R qualification are especially challenging because of the narrow purposeof the qualification. The paper offers an analysis of various models of knowledge typesand mixes, outlining each one’s purpose. Finally, the paper provides an epistemologicaldistillation in a conceptual framework which can guide the process of curriculum making,offering all participants a chance to contribute to the layers underneath the patina of thepainting that offers life to the curriculum.
Examining oral reading fluency among Grade 5 rural English Second Language (ESL) learners in South Africa? An analysis of NEEDU 2013
Authors: Draper Kim , Spaull Nic
Published: February 2018

The ability to read for meaning and pleasure is arguably the most important skill children learn in primary school. One integral component of learning to read is Oral Reading Fluency (ORF), defined as the ability to read text quickly, accurately, and with meaningful expression. Although widely acknowledged in the literature as important, to date there have been no large-scale studies on ORF in English in South Africa, despite this being the language of learning and teaching for 80% of ESL students from Grade 4 onwards. We analyze data provided by the National Education and Evaluation Development Unit (NEEDU) of South Africa, which tested 4667 Grade 5 English Second Language (ESL) students from 214 schools across rural areas in South Africa in 2013. This included ORF and comprehension measures for a subset of 1772 students. We find that 41% of the sample were non-readers in English (<40 Words Correct Per Minute, WCPM) and only 6% achieved comprehension scores above 60%. By calibrating comprehension levels and WCPM rates we develop tentative benchmarks and argue that a range of 90-100 WCPM in English is acceptable for Grade 5 ESL students in South Africa. In addition we outline policy priorities for remedying the reading crisis in the country.
Parallelization of the numerical simulation of motion of deformable objects within fluid domain on a GPU device
Authors: Djukic T. , Filipovic N.
Published: February 2018

Computationally demanding numerical simulations can be significantly accelerated using GPU (Graphics Processing Unit) devices. This way, the results of the simulation can be observed in real time. In this paper, the principles of GPU programming are used to simulate the movement of deformable objects within fluid domain. Lattice Boltzmann (LB) method is used to simulate fluid flow. The solid-fluid interaction is modeled using the Immersed boundary method. The developed software was tested on a Tesla GPU device; the execution time of parallelized version and sequential version of the software are compared and significant speed-up is obtained. Fluid flow simulations in the field of biomedicine that needed up to several hours to be performed, can now be completed in just a few minutes.
Stochastic homogenization of quasilinear Hamilton–Jacobi equations and geometric motions
Authors: Armstrong Scott , Cardaliaguet Pierre
Published: February 2018

We study random homogenization of second-order, degenerate and quasilinear Hamilton–Jacobi equations which are positively homogeneous in the gradient. Included are the equations of forced mean curvature motion and others describing geometric motions of level sets as well as a large class of viscous, non-convex Hamilton–Jacobi equations. The main results include the first proof of qualitative stochastic homogenization for such equations. We also present quantitative error estimates which give an algebraic rate of homogenization.
Vectorial nonlinear potential theory
Authors: Kuusi Tuomo , Mingione Giuseppe
Published: February 2018

We settle the longstanding problem of establishing pointwise potential estimates for vectorial solutions

u\colon \Omega \to \mathbb R^{N}

to the non-homogeneous

p

-Laplacean system

-\mathrm{div} (|Du|^{p-2}Du)=\mu \qquad \text{in}\ \Omega \subset \mathbb R^{n}\,,

where

\mu

is a

\mathbb R^{N}

-valued measure with finite total mass. In particular, for solutions

u \in W^{1,1}(\mathbb R^{n})

, the global estimates via Riesz and Wolff potentials

|Du(x_0)|^{p-1} \lesssim \int_{\mathbb R^{n}}\frac{d|\mu|(x)}{|x-x_0|^{n-1}}

and

|u(x_0)|\lesssim {\bf W}^{\mu}_{1, p}(x_0,\infty) = \int_0^\infty \left(\frac{|\mu|(B_\varrho(x_0))}{\varrho^{n-p}}\right)^{1/(p-1)}\, \frac{d\varrho}{\varrho}

respectively, hold at every point

x_0

such that the corresponding potentials are finite. The estimates allow to give sharp descriptions of fine properties of solutions which are the exact analog of the ones in classical linear potential theory. For instance, sharp characterisation of Lebesgue points of

u

and

Du

and optimal regularity criteria for solutions are provided exclusively in terms of potentials.
Perspectivas de los estudiantes mexicanos sobre competencias en TIC, definidas por género
Authors: Bordas-Beltrán José-Luis , Arras-Vota Ana-María de Guadalupe
Published: February 2018

Hoy en día los seres humanos viven entornos que siempre están en movimiento, es por ello que las Instituciones de Educación Superior (IES), en México, deben estarse innovando y dar respuesta al mercado laboral; se requiere que incluyan en su formación, el manejo efectivo de las Tecnologías de Información y Comunicación (TIC), que demandan competencias para que los estudiantes logren un aprendizaje significativo. Metodología: Esta Investigación se llevó a cabo con estudiantes participantes del XI Maratón Nacional de conocimientos de la Asociación Nacional de Facultades y Escuelas de Contaduría y Administración (ANFECA) en México. Resultados y discusión: Los datos muestran una confianza mayor en las mujeres que en los hombres en cuanto al desarrollo de sus competencias en TIC; en cuanto al comparativo de las zonas de ANFECA se presentan las diferencias más representativas
Supporting the UN SDGs transition: methodology for sustainability assessment and current worldwide ranking
Authors: Campagnolo Lorenza , Eboli Fabio , Farnia Luca , Carraro Carlo
Published: February 2018

This analysis lies in the stream of research related to the quantitative assessment of the Sustainable Development Goals (SDGs), adopted by the United Nations at the end of September 2015. We assemble a composite multi-dimensional index and a worldwide ranking of current sustainability. This makes it possible to assess the strengths and weaknesses of today’s socio-economic development, as well as environmental criticalities worldwide. The methodology goes through the following steps: screening of indicators capable of addressing the UN’s SDGs; data collection from relevant sources; organization into three pillars of sustainability (economy, society, and environment); normalization to a common metrics; aggregation of the 26 indicators into composite indices by pillars as well as in a multi-dimensional index. The final ranking includes 139 countries. Sweden, Norway and Switzerland are at the top of the ranking.
Verslaggeving van toegelaten instellingen volkshuisvesting
Authors: Jungheim Ernst-Jan , Suurland Lianne
Published: February 2018

Dit artikel beschrijft de uitkomsten van het onderzoek naar de wijze waarop woningcorporaties de wijzigingen in de Woningwet, de daarmee samenhangende regelgeving en RJ 645 hebben verwerkt en toegelicht in de jaarrekening over 2016. Het artikel richt zich op de gevolgen van de verplichte waardering van het vastgoed in exploitatie tegen marktwaarde. Uit het onderzoek blijkt dat de overgang naar waardering tegen marktwaarde heeft geleid tot een omvangrijke stijging van het eigen vermogen en het resultaat van woningcorporaties. Uit het onderzoek blijkt verder dat woningcorporaties de toelichtingen van de marktwaarde kunnen verbeteren. Tot slot constateren wij dat woningcorporaties verschillend om zijn gegaan met de verwerking en toelichting van de bedrijfswaarde en de belastinglatenties, hetgeen de vergelijkbaarheid tussen woningcorporaties niet ten goede komt.