bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Study on a Steel-Tube Damper
Authors: Sun Ying Zhi , Li Guo Qiang , Sun Fei Fei
Published: February 2018

The steel-tube damper is composed of two parts: the inner component inside the tube and the outer seamless steel-tube with the energy dissipation steel strips. The two parts are connected by plug welding and fillet welding. The yield bearing capacity of the steel strips is lower than the stability bearing capacity of both inner I-section component and outer seamless steel-tube. As the load increases, the steel strips will yield first and dissipate the input energy withholding the buckling of the inner I-section component and the seamless steel-tube. In order to further determine its mechanical property, three groups of specimens with steel strips of different aspect ratio were designed, and the hysteretic loading tests were carried out. It was found from the tests that: 1) The hysteresis curves of the damper were full and the energy dissipation capacity was good; 2) Specimens with steel strips of small aspect ratio had larger stiffness, yield bearing capacity and energy dissipation capability per cycle. 3) Specimens with steel strips of small aspect ratio had worse low cycle fatigue performance compared with the ones with steel strips of larger aspect ratio. This study provides a foundation for further research and application of such dampers.
Shake Table Testing of a Low Damage Steel Building with Asymmetric Friction Connections (AFC)
Authors: Rad Ali A. , MacRae Gregory A. , Hazaveh Nikoo K. , Ma Quincy T.
Published: February 2018

The paper describes the shaking table performance of a half-scale two-story steel moment frame with asymmetric friction connections (AFCs) at the column bases and at the beam ends. The results showed that the beam ends and the base-column joints exhibited bilinear and trilinear response respectively. Residual drifts were less than 0.2% for shake table trials up to 3% peak inter-story drift. Even at a peak inter-story drift of 6.5%, the residual drift response was still only 0.7%.
Shake Table Testing of Lightweight Steel Drywall Nonstructural Components
Authors: Bucciero Bianca , Pali Tatiana , Terracciano Maria Teresa , Macillo Vincenzo , Fiorino Luigi , Landolfo Raffaele
Published: February 2018

Damages of non-structural components during a seismic event can involve risks for the human life, interruption of ordinary activities and significant economic losses. Therefore, the understanding of the seismic behaviour of non-structural components is a fundamental prerequisite for their use. In this context, a cooperation between the University of Naples "Federico II" and KnaufGips KG Company, aimed to the knowledge of seismic response of lightweight steel drywall non-structural components was carried forward. In this framework, shake table tests were carried out on protoypes composed by indoor partition walls, outdoor façade walls and suspended continuous ceilings. The influence on seismic response of basic and enhanced anti-seismic solutions, corresponding to the use of fixed or sliding connections at the walls and ceilings perimeter, was investigated. The seismic response in terms of damage occurrence was also evaluated by fragility curves, which show that enhanced solutions have a better seismic response than basic solutions and indoor partition walls have a higher seismic “fragility” than outdoor façade walls.
Behaviour of Square Tubular Columns in Connection to I Beams with Welded Reverse Channel under Experimental Tests
Authors: Magalhães Luís , Rebelo Carlos , Jordão Sandra
Published: February 2018

This article presents some results of the experimental monotonic bending tests on the behaviour of the tubular columns and the reverse channel, effected based on a parametric variation of the most significant characteristics of the tubular profiles. The parameters considered are the thicknesses and the widths of the tubular columns faces, the filling with concrete and the axial load. The experimental tests program, included in the framework of the Doctoral Program Thesis in the scientific domain of the Steel Composite Structures, were performed on a test layout, corresponds to a framed structure, in the Structural Mechanic Laboratory of the Department of Civil Engineering of the University of Coimbra. The objective is to determine the characteristics of the nonlinear cyclic behaviour of the principal components of the tubular columns and the reverse channel, in this shape of joints. These components are related to the tubular columns walls, and to the web and flanges of the reverse channel yielding, crushing or instability, when submitted to bending, shear, compression and tension. The results of this experimental tests allow correlate the parameters considered with the structural behaviour of the connection, defined by the resistance, the stiffness, and the rotation capability.
Comparison of Hysteretic Models for Steel Beams Calibrated by Means of Multi-Objective Optimisation
Authors: Chisari Corrado , Rizzano Gianvittorio
Published: February 2018

Phenomenological models are often used to model post-elastic behaviour of steel members in the framework of concentrated-plasticity approach. Many of them can simulate degradation phenomena occurring during cyclic loading, but are dependent on model parameters without clear physical meaning. To overcome this issue, parameter calibration should be performed by curve fitting of experimental responses. In this work, several numerical models implemented in widely used software packages are calibrated against the results provided by an experimental programme involving cyclic and monotonic tests on open and closed cross-section profiles, according a multi-objective methodology recently developed by the authors. The extensive calibration analyses carried out show that the most reliable model among those investigated is the Sivalselvan-Reinhorn model, which is able to provide accurate simulation of both monotonic and cyclic responses. Extension of the calibration procedure is proposed, with an additional objective related to the envelope curve of the cyclic response, and it is shown that this improvement adds robustness to the results.
High-Performance Computer-Aided Optimization of Viscous Dampers for Improving the Seismic Performance of a Tall Steel Building
Authors: Wang Shan Shan , Mahin Stephen
Published: February 2018

Using fluid viscous dampers (FVDs) has been demonstrated to be an effective method to improve seismic performance of new and existing buildings. In engineering applications, designs of these dampers mainly rely on trial and error, which could be repetitive and labor intensive. To improve this tedious manual process, it is beneficial to explore more formal and automated approaches that rely on recent advances in software applications for nonlinear dynamic analysis, performance-based evaluation, and workflow management and the computational power of high-performance, parallel processing computers. The optimization design procedure follows the framework of Performance Based Earthquake Engineering (PBEE) and uses an automatic tool that incorporates an optimization engine and structural analysis software: Open System for Earthquake Engineering Simulation (OpenSEES). An existing 35-story steel moment frame is selected as a case-study building for verification of this procedure. The goal of the retrofit design of FVDs is to improve the building’s seismic behavior that focuses on avoiding collapse under a basic-safety, level-2 earthquake (BSE-2E). The objective of the optimization procedure is to reduce the building’s total loss under a BSE-2E event and optimal damper patterns will be proposed. The efficiency of the optimization procedure will be demonstrated and compared with a manual refinement procedure.
Finite Element Analysis of Eccentrically Braced Frames with Removable Link
Authors: Mago Nandor , Cowie Kevin , Clifton George Charles
Published: February 2018

Steel eccentrically braced frames (EBFs) are expected to sustain damage during an ultimate limit state design level earthquake through repeated cyclic plastic deformation of the active link. Traditionally the active link has been integral with the collector beam, but following the 2010/2011 Canterbury earthquakes, the benefit of having a readily replaceable active link became apparent. The development of this was undertaken by New Zealand Heavy Engineer Research Association (HERA) and Steel Construction New Zealand (SCNZ), with input from the University of Auckland. This paper describes the finite element analyses performed to determine the behaviour of the system including the bolted endplate connections through the range of inelastic cyclic loading expected. The numerical simulations answer a number of questions, like at which loading cycle the von Mises stress is above 300MPa in collector beam adjacent to the removable link; history of all bolt forces; component forces (shear) in slab and removable link; rotation of the link versus cycles; equivalent plastic strain contour for the last cycle and others. This paper also describes how the interaction with the concrete slab was modelled in the elastic and inelastic range.
Numerical Model of Cold Press-Formed Square Steel Tube Columns Considered with Degradation Behavior due to Local Buckling and/or Fracture
Authors: Koetaka Yuji , Taniguchi Koichi , Chan Iathong
Published: February 2018

In steel building structures, local buckling and/or fracture of columns could occur during strong ground motions, furthermore complete collapse might be induced due to the column strength degradation. In this paper, cold press-formed square tube columns are targeted, and numerical model being able to trace precisely degradation behavior is proposed. In order to take account of both local buckling and fracture with low computational costs, multi-spring model which consists of some uni-axial springs is adopted. Axial force-deformation relationships of uni-axial springs are provided on flat area and corner area of square tube severally, and are separated into skeleton part and hysteresis part. All parameters on force-deformation relationship are identified based on finite element analysis results of short columns under monotonic or cyclic axial loading. Comparing between analysis results by multi-spring models and past cyclic loading test results or finite element analysis results, it is clarified that degradation behavior of cold press-formed square steel tube columns can be traced with high accuracy.
Development of a Hybrid Simulation Computational Model for Steel Braced Frames
Authors: Imanpour Ali , Tremblay Robert , Leclerc Martin , Siguier Romain
Published: February 2018

Hybrid simulation is an economical structural testing technique in which the critical part of the structure expected to respond in the inelastic range is tested physically whereas the rest of the structure is modelled numerically using a finite element analysis program. The article describes the development of a computational model for the hybrid simulation of the seismic collapse of a steel two-tiered braced frame structure due to column buckling. The column stability response in multi-tiered braced frames is first presented using a pure numerical model of the braced frame studied. The development of the hybrid simulation computational model is then discussed. Effects of initial out-of-straightness imperfections and axial stiffness, P-Delta analysis approach, and gravity analysis technique on the hybrid simulation results are evaluated using a numerical hybrid simulation model. Finally, the results of a continuous pseudo-dynamic hybrid simulation of the seismic response of the steel multi-tiered concentrically braced frame are presented. The test showed that failure of columns by instability is a possibility and can lead to collapse of multi-tiered braced frames, as was predicted by numerical analysis. Furthermore, suitable modeling methods are proposed for hybrid simulation of steel braced frame structures.
Collapse Analysis of Steel Frames Considering Fracture of Braces and End of Beams
Authors: Matsui Ryota , Takeuchi Toru , Urui Shunji , Tokuno Masaki
Published: February 2018

The 2011 Tohoku Earthquake ruptured multiple faults simultaneously, generating strong ground motions over a long duration at long periods. Such severe events have recently begun to be considered in structural design, requiring explicit calculation of the low cycle fatigue capacity and fracture point. This paper presents a numerical study of dual moment and braced frames, with either conventional or buckling-restrained braces. Both brace and beam end fracture is considered, and incremental dynamic analysis (IDA) used to determine the ultimate failure mechanism under extremely large ground motions. Fragility curves are generated, demonstrating the significant role that member fracture has on the seismic performance of braced frames.
An Empirical Methodology for Seismic Damage Control of CFT-MRFs
Authors: Kamaris Georgios S. , Skalomenos Konstantinos A. , Hatzigeorgiou George D. , Beskos Dimitri E.
Published: February 2018

An empirical methodology to evaluate damage by the use of two damage indicators for 2D steel/concrete composite structures is proposed. This methodology has been established with aid of the results of an extensive parametric study regarding the non-linear behaviour of 48 steel/concrete composite frames subjected to 100 far-fault records. A large number of inelastic dynamic analyses are conducted by increasing the earthquake motions to lead the frames to several levels of non-linear response. The results of the analyses show that the characteristics of the structure and the ground motions affect damage of the structures. The results are post-processed by the use of statistical methods to generate expressions, which show the effect of the abovementioned parameters and give an evaluation of the damage indicators utilised here. In particular, given the characteristics of the frames and the record, someone can compute the maximum damage found in beams and columns. Finally, one example serves to show the use of the developed formulae and demonstrates their validity.
Cyclic Response of Steel Cladding Details with Fiber-Reinforced Polymer Shims
Authors: Peterman Kara , Webster Mark , D'Aloisio James , Hajjar Jerome
Published: February 2018

Cladding details which span the building envelope are particularly susceptible to forming thermal bridges, where heat is transferred between interior and exterior, resulting in loss of energy. To prevent these thermal bridges, thermal breaks inserted in the cladding detail connection to the building interior are necessary. This paper summarizes recent work on the design, validation, and implementation of thermal break strategies. Fiber-reinforced polymer (FRP) shims were used to provide thermal breaks in steel connections of cladding details. The use of these shims was due to their combination of favorable thermal properties and promising structural performance. While several cladding details were examined, this paper will concentrate on the cyclic performance of roof posts (under axial and cyclic lateral loads) and canopy beams (under cyclic lateral loads only), representing their anticipated performance during earthquakes. The impact of FRP shims at the bolted base plate connection to the building interior is discussed. Recommendations for design are also presented.
Experimental Study and Numerical Assessment of the Flexural Behaviour of Square and Rectangular CFST Members under Monotonic and Cyclic Loading
Authors: Jiang Ya Dong , Silva Antonio , Castro José Miguel , Chan Tak Ming , Monteiro Ricardo
Published: February 2018

This paper focuses on the characterization of the behaviour of Concrete Filled Steel Tubular (CFST) columns made with Rubberized Concrete (RuC), and on the development of an accurate numerical model for the simulation of CFST columns under monotonic and cyclic bending. The test campaign involves 18 CFST specimens with different configurations, namely the cross-section slenderness, the concrete strength, the axial load level and the lateral loading type. All CFST members tested exhibited good ductility under monotonic loading. The Eurocode 4 design provisions was verified against the test results and the design capacities of the CFST members were validated to be conservative. A comprehensive 3D Finite Element (FE) model was developed and calibrated based on test results. The FE model proved to be reliable in predicting the bending behaviour of CFST member, in terms of local buckling deformation modes, ultimate capacity and ductility of the CFST columns.
Low-Cycle Fatigue Performance of Buckling Restrained Braces and Assessment of Cumulative Damage under Severe Earthquakes
Authors: Liu Yu Shu , Chen Ke Peng , Li Guo Qiang , Sun Fei Fei
Published: February 2018

Buckling Restrained Braces (BRBs) are effective energy dissipation devices. The key advantages of BRB are its comparable tensile and compressive behavior and stable energy dissipation capacity. In this paper, low-cycle fatigue performance of domestic BRBs is obtained based on collected experimental data under constant and variable amplitude loadings. The results show that the relationship between fatigue life and strain amplitude satisfies the Mason-Coffin equation. By adopting theory of structural reliability, this paper presents several allowable fatigue life curves with different confidential levels. Besides, Palmgren-Miner method was used for calculating BRB cumulative damages. An allowable damage factor with 95% confidential level is put forward for assessing damage under variable amplitude fatigue. In addition, this paper presents an empirical criterion with rain flow algorithm, which may be used to predict the fracture of BRBs under severe earthquakes and provide theory and method for their engineering application. Finally, the conclusions of the paper were vilified through precise yet conservative prediction of the fatigue failure of BRB.
Seismic Design of Buckling-Restrained Brace in Preventing Local Buckling Failure
Authors: Lin Pao Chun , Takeuchi Toru , Matsui Ryota , Sitler Ben
Published: February 2018

When a buckling-restrained brace (BRB) is composed of a flat steel core encased in a rectangular steel tube with infill mortar, the flat steel core develops high-mode buckling waves within the spaces occupied by compressible debonding layers when BRB is in compression. The wave crests and troughs collide with mortar and then acting outward forces on restrainer. The steel tube wall may bulge out if the restrainer is too weak to sustain the outward forces and the BRB may lose its compression carrying capability. The outward force can be estimated according to steel core high-mode buckling wavelength and the debonding layer thickness. The restrainer capacity in resisting outward forces can be estimated by using the upper bound theory in plastic analysis. The results of 39 BRB tests were compared in order to evaluate the effectiveness of steel tube capacity estimation methods. 24 BRBs exhibiting local bulging failure suggested that the steel tube capacity can be estimated by assuming the bulged wall as a wedge shape with five of its boundary developing flexural strength. The proposed estimation is conservative and can be adopted for BRB design in preventing local bulging failure for severe seismic services.
Performance Evaluation of Buckling-Restrained Braces Installed in a Mid-Rise Steel Structure
Authors: Narui Ryohei , Koyano Kazuhisa , Midorikawa Mitsumasa , Nakagomi Tadao , Iwata Mamoru
Published: February 2018

The authors have continuously studied buckling-restrained braces using steel mortar planks (BRBSM). The performance of energy absorption and fatigue against cyclic loading has been evaluated. Although past studies have clarified the structural performance of BRBSM as single member, it is necessary to study not only the performance of BRBSM as single member but also the performance of BRBSM installed in a building structure. In this paper, a frame model of mid-rise steel structure with BRBSM subjected to earthquake motions with various characteristics is analyzed. Comparing the results of the analysis and the past tests, the seismic behavior of a structure is discussed. Especially, the seismic performance of BRBSM installed in the building structure is evaluated. In addition, the seismic performance of two types of BRBSM; basic and developed high-performance types, is compared and evaluated about cumulative plastic strain energy ratio and cumulative fatigue. As a result, the performance capacities of the both types of BRBSM exceed the required values of BRBSM under severe earthquake motions about cumulative plastic strain energy ratio and cumulative fatigue. The basic-type BRBSM has the fatigue capacity against 2 to 5 times severe earthquake motions. The required values of high-performance-type BRBSM are about a half of accumulated fatigue capacity compared with the basic-type one. The high-performance-type BRBSM is applicable against quite many cyclic loadings of low strain amplitude, and able to be used for long-term service.
Seismic Stability of Buckling-Restrained Braced Frames
Authors: Zaruma Santiago R. , Fahnestock Larry A.
Published: February 2018

Buckling Restrained Braced Frames (BRBFs) are widely used as seismic force resisting systems due to their ductility and energy dissipation. However, because of the modest overstrength and relatively low post-yielding stiffness, BRBFs subjected to seismic loading may be susceptible to concentrations of story drift and global instability triggered by P-∆ effects. Due to the use of simplistic methods that are based on elastic stability, current code design provisions do not address seismic stability rigorously and do not consider the particular inelastic response of a system. Design strategies are needed to prevent undesirable seismic response in BRBFs, such as drift concentration and large residual drift. This study used the FEMA P-695 Methodology to evaluate the response of current U.S. code-based BRBF designs and to study the effect on seismic stability of three potential enhancements: strong-axis orientation for BRBF columns, gravity column contribution, and a BRBF-SMRF dual system. Results from nonlinear static and dynamic analyses allowed assessment of seismic behavior. Results from collapse performance evaluation quantify the improvement that is achieved with each alternative and provide a means of comparison.
Mechanical Behavior of Assembled Steel Dampers with Optimized Shapes
Authors: Zhu Bai Jie , Wang Tao , Zhang Ling Xin
Published: February 2018

A metallic shear damper is developed with the shape optimized by stress contour lines to mitigate the stress concentration, reduce the effect of hot welds, and improve the efficiency of energy consumption. The stress contour line is defined according to the J2 plasticity theory, where the micro units yield simultaneously. To demonstrate the effectiveness of the proposed shape-optimization method and the correctness of design formulas, detailed FEM models were built for nine dampers. And the influence of the axial loads was studied as well. Finally, seven damper specimens were fabricated and tested quasi-statically, including six optimized dampers and one with a rectangle shape as a comparison. Both numerical simulation and physical tests demonstrate that the distribution of plastic deformation is more uniform, and the accumulated equivalent plastic strain is reduced significantly, compared with the non-optimized damper. The proposed metallic shear damper has a good low-cycle fatigue capability and a stable energy-dissipation capacity. The stiffness and strength design equations predicted the specimen performance very well.
The Use of TPMC for Designing MRFs Equipped with FREEDAM Connections: Performance Evaluation
Authors: Montuori Rosario , Nastri Elide , Piluso Vincenzo , Streppone Simona
Published: February 2018

The work herein presented is devoted to the validation of TPMC design procedure applied to steel MRFs equipped with FREEDAM dampers located at beam-to-column joints. The seismic performances evaluations of the designed structure have been carried out by means of both Push-over analysis and Incremental Dynamic Analysis. In particular, the Push-over analysis aims to confirm the real development of a collapse mechanism of global type, while, through IDA analysis, Maximum Interstorey Drift and Top Residual Displacement performed by the designed structures have been pointed out. For this reason, a MRF whose design procedure by TPMC is detailed in a companion paper has been subjected to both push-over and IDA analysis.
Finite Element Analysis on Single Abrasive Grinding Ti6Al4V Alloy
Authors: Huo Wen Guo , Zhang Xiang Yu , Dong Qing Yun , Shao Juan
Published: February 2018

The paper presents the simulated 3D Finite Element Model (FEM) while grinding the Ti6Al4V alloy using a single abrasive wheel. Grinding simulation was carried out using a Lagrangian finite element based machining model to predict the tangential cutting force, temperature distribution at grinding zone and the effective stress and strain. All simulations were performed according to the cutting conditions designed, using the plane up-grinding. The work piece was considered as typical materials to machine difficulty. As the cutting speed is increased from 15 m/min to 33 m/min at higher feed rate, a maximum value of 750 MPa stress and higher temperature localization to an extent of 900°C at grinding zone were observed.
Nanosecond Laser Direct-Part Marking of Data Matrix Symbols on Titanium Alloy Substrates
Authors: Li Chun Ling , Lu Chang Hou , Li Jian Mei
Published: February 2018

In the application of laser marking, the biggest challenge is that machine-readable barcodes with superior quality were not marked consistently. To solve this problem, laser direct-part marking Data Matrix barcode experiments were carried out on titanium alloy substrates, using a Q-switched light-pumped Nd:YAG laser. The microstructure of the symbols was analyzed using an environmental scanning electron microscope (ESEM). The internal micro-stresses of the marked areas were analyzed using X-ray diffractometer (XRD). The influence of the pulse frequency on the symbol contrast is analyzed. Results showed the interaction between the laser and the titanium alloy can be found. This can further explain the physical mechanism of laser direct part marking Data Matrix symbols on titanium alloy substrates.
Research on the Quality of Laser Marked Data Matrix Symbols
Authors: Li Chun Ling , Lu Chang Hou , Li Jian Mei
Published: February 2018

To evaluate the quality of the laser direct part marked Data Matrix symbols on titanium alloy substrates, the quality assessment methods at home and abroad were compared. A new quality assessment method of combining the effect of the laser on substrate materials and symbol grade of laser marked Data Matrix was put forward. Depending on previous research works, orthogonal experiment results were analyzed again and a modified nonlinear mathematics model was established. Analysis results indicate that this modified model can explain 90.6% of symbol contrast change and it is statistically significant. So it is better than previous linear regression model and can be used to estimate the quality of laser marked Data Matrix symbols on titanium alloy substrates. The nonlinear mathematics model can also explain the laser parameters influence on the symbol contrast.
Simulation Analysis of RuT450 Drilling Force Based on LS-DYNA Gun Drilling
Authors: Guo H. , Yang W. , Liu L. , Yang X.K. , Wang Y.G. , Chen L. , Ge H.
Published: February 2018

Cutting force is one of the most important parameters in the machining process, it significantly influenced machining precision of the workpiece, power consumed in the machining process, wear of the cutting tools and so on. There are many factors that affect the cutting force, such as the performance of the workpiece material, cutting speed, usage of the cutting fluid, etc. Single factor variable method was used in this paper, RuT450 was used as workpiece, welded cemented carbide gun drill was used as cutting force and LS-DYNA was used as simulation platform to established the cutting simulation model to analyzed the impact of the cutting speed and feed rate to the drilling force. Simulation results show that, at the low speed drilling stage, drilling force increases with the increase of the feed rate and decreases with the increase of the rotation feed, from the stress cloud it could be seen that the equivalent stress near the drill tip reached the maximum in the drilling process.
Research on Metamorphic Vibration Casting Process Based on EDEM-FLUENT Coupling
Authors: Wang Cheng Jun , Zheng Yan , Liu Kai
Published: February 2018

In order to reduce the defects of investment casting and improve its casting quality, vibration technology and casting technology are combined effectively and the effect of vibration degree of freedom, frequency and amplitude on the filling ability of liquid metal are studied by means of EDEM-FLUENT solid liquid coupling visualization. With the use of orthogonal test method, the sensitivity of the particles towards each parameter index is obtained. Optimal vibration parameters are chosen and then the best variable cell vibration casting solution is obtained.
Analysis of Computational Model of Seamless Steel Pipe Rolling Contact Force
Authors: Li Lian Jin , Han Xing , Liu Si Qi
Published: February 2018

Due to the problems that the rolling force of seamless steel tube during tandem rolling process is affected by many factors, the calculation is complex and the accuracy is not enough. In order to improve the rolling force calculation accuracy of the tandem rolling mill, analyze the metal flow, stress distribution rules and cross section deformation characteristics during the rolling process of seamless steel tube, calculation of the rolling force was divided into the reduced-diameter area and the reduction of wall area, and a new calculation method was proposed, which concerns the rolling force in reduced-diameter area related to the material yield stress, friction coefficient and the crushing stress of the tube, while the rolling force in the reduction of wall area is only related to the material yield stress and the friction coefficient. The results show that the calculated rolling force is in agreement with the measured values with errors less than ±10%. The model satisfies the actual conditions and is applicable to engineering application.
Grinding Process of Ball End Milling Cutter Flank
Authors: Xin Quan Qi , Wang Tai Yong , Yu Zhi Qiang , Hu Hong Yan
Published: February 2018

In this paper, the mathematical model of "S" - shaped cutting-edge curve is optimized, and the position and orientation of the grinding wheel of the first and second flank of the ball end milling cutter are calculated, The correctness of the algorithm is verified by VERICUT simulation.
Dynamic Response Analysis of Tandem Rolling Mill in Rolling Process
Authors: Han Xing , Li Lian Jin
Published: February 2018

Due to the influence of rolling force fluctuations, tube size changes and material uniformity and other factors, vibration and other phenomenon inevitably occur in the rolling process of tandem rolling mill. This vibration has a great impact on the dynamic stability of the mill and rolling reduction, and will significantly reduce the dimensional accuracy and surface quality of seamless steel pipe. In this paper, the non-linear finite element software ABAQUS is used to simulate the rolling process of seamless steel pipe. First, rolling force of the first frame with the maximum rolling force of PQF rolling mill is calculated. The reliability of rolling force calculated by the finite element method is verified by the test experiment. The dynamic response analysis of the roll is carried out to obtain the dynamic response curve of the roll in the rolling state and to provide technical support for the rolling schedule with the calculated rolling force being the load.
Quantum Dot-Peptide Nanoassembly on Mesoporous Silica Nanoparticle for Biosensing
Authors: Pillai Sreenadh Sasidharan , Yukawa Hiroshi , Onoshima Daisuke , Biju Vasudevanpillai , Baba Yoshinobu
Published: February 2018

Quantum dots (QDs) are powerful luminescent probes for detecting single-molecules and imaging live cells. Despite several reports on bioimaging and biosensing applications of QDs, controlled and targeted detection of biomolecules using quantum dots is an ongoing challenge. When a QD is conjugated with an ideal chromophore, which can be a fluorescent or a non-fluorescent dye molecule, QD luminescence can be quenched by Förster resonance energy transfer (FRET) to the quencher dye. However, the photoluminescence of QD can be recovered upon on-demand release of the quencher. Our study focuses on quenching of QD photoluminescence after conjugation with a non-fluorescent dye molecule, black hole quencher 1 (BHQ-1), intermediated with a molecular sensing target peptide GPLG↓VRGK. Based on steady-state and time-resolved photoluminescence measurements of QD and the QD-peptide-BHQ-1 sensor assemblies, we attribute the quenching of photoluminescence intensity and lifetime to FRET from the QD to BHQ-1molecules. Here the intermediate peptide GPLG↓VRGK can be cleaved by matrix metalloproteinase-2 (MMP-2), an enzyme that is upregulated in cancer cells extra cellular matrix (ECM), at its Gly and Val region shown by the down headed arrow. Here the QD-pep-BHQ-1 conjugate detected the MMP-2 presence at the extra cellular matrix of H1299 cancer cells. Further the QD-pep-BHQ-1 molecules were conjugated at the surface of a mesoporous silica nanoparticle (MSN) scaffold to localize maximum target peptide in a nanospace volume for the future αvβ3 integrin receptor targeted detection of MMP-2. The luminescence quenching of MSN-QD-pep-BHQ-1 conjugates were analyzed with time resolved photoluminescence measurement.
Sondagviering
Authors: Van der Walt S. P.
Published: February 2018

Ons is daaraan so gewoond en aanvaar alles sonder om weer daaroor na te dink: Op Sondag kom alles tot rus. Die winkels is gesluit en kantore is toe, plekke van openbare vermaak en sportvelde is onbevolk. Christene is ook in hul huise stemmiger as op ander dae en ouers gaan met hul kinders kerk toe. Kinders neem nie aan alle vorme van vermaak deel nie, gaan byvoorbeeld nie na swembaddens of riviere toe nie. Daar kom ’n wyding op die dag en dit het deel van ons lewenspatroon geword. Toe het die skokke gekom — van andersdenkendes en -voelendes, wat Sondag nie in sy gewydheid wou onderhou nie, maar die dag vir hulleself toegeëien het.
Hold the candle: mission at the crossroads in our era
Authors: Kommers J.
Published: February 2018

When we rounded the bend from the second to the third millennium the contribution of the classic pioneer missionary is over. The 21st century is dominated by a holistic approach. However, in using new methods, new technology and in adapting a lifestyle according to this time, there is a tendency to view the work of pioneer missionaries as old fashioned. With a new approach and new methods also new ideas enter the field. My intention is not to defend the pioneers and to give them more recognition – the Lord will honour his own work and workers – but to show that we do ourselves an injustice when we would not use the knowledge, experience, love and passion of the former generations who just had only one vision. We need them to fuel our mission intention in obeying Christ’s last commend in the conviction that the message of the cross of Jesus Christ is the only relevant message for today’s world.
A liberalised South African airline industry: Measuring airline
Authors: Brits Anton
Published: February 2018

The liberalisation of the South African airline industry through economic deregulation established competitive domestic and international markets. Sustainability of air transport, subject to these liberalisation effects, depends on efficient management information such as total-factor productivity, which necessitates comprehensive financial and operational information. Total-factor productivity in general, however, is not utilised by airlines as a key performance indicator since the measuring thereof is complex and regarded as tedious. Changes in air transport total-factor productivity can be measured in two ways. First, an index approach can be adopted that shows the proportional change in the inputs in relation to a proportional change in output. Secondly, a production function can be determined (econometric approach) that shows a change of productivity as a shift in the production curve. The research on which the article is based, exploited the theory, selection and application of an appropriate approach to determine changes of total-factor productivity of an individual airline to assist/support efficient decisionmaking by management.
Editorial
Authors: Henning Elizabeth
Published: February 2018

No abstract available.
The readiness of the South African education system for pre-grade R year
Authors: Kotze Janeli
Published: February 2018

Investment in Early Childhood Development (ECD) has the prospect of cultivating potential within individuals and can assist in bridging the social equity gap from a very young age. Over the past decade Grade R has been the strongest policy lever used by the Department of Basic Education to improve early learning. The National Development Plan calls for universal access to two years of early childhood development prior to entering Grade 1. This paper explores the merits of this proposal, given the specific South African context. More specifically, this analysis intents to bring new information to bear on three matters. The first relates to the demand-side and aims to identify participation trends among four and five year olds. The second objective is to consider the supply-side and aims to understand the policy space in which pre-Grade R will function, the quality and quantity of infrastructure already in place, and the expertise of ECD practitioners. The final question considers the implementation of a universally accessible pre-Grade R within a constrained system and the requirements to ensure that it will have a significant impact on those children most in need.
Effect of Modeling Variables upon Projection of Corrosion-Induced Bridge Post-Tension Tendon Failures
Authors: Hartt William H.
Published: February 2018

Construction via post-tensioning (PT) has evolved over the past 60 y as an often preferred approach to affecting integrity for large concrete structures. In the case of bridges, tendon ducts typically contain multiple 15.24 mm (0.600 in) diameter, seven wire strands of minimum tensile strength 1,960 kN (270 ksi), and are invariably grouted. However, failures have been reported as a consequence of corrosion caused by either chemically or physically deficient grout. In response to this a methodology was developed and reported whereby the timing of wire and strand fractures and tendon failures can be projected. The present paper reviews basics of the modeling approach and evaluates the influence of modeling variables upon failure projections. These variables include the following: (1) analysis variables (generation of random numbers), (2) strand/tendon stress, (3) wire/strand strength, (4) number of tendons, and (5) tendon length. The significance of each is discussed and results are related to the timing of tendon failures on bridge structures.
Information content analysis: the potential for methane isotopologue retrieval from GOSAT-2
Authors: Malina Edward , Yoshida Yukio , Matsunaga Tsuneo , Muller Jan-Peter
Published: February 2018

Abstract. Atmospheric methane is comprised of multiple isotopic molecules,
with the most abundant being 12CH4 and 13CH4, making up 98
and 1.1 % of atmospheric methane respectively. It has been shown that is
it possible to distinguish between sources of methane (biogenic methane, e.g.
marshland, or abiogenic methane, e.g. fracking) via a ratio of these main
methane isotopologues, otherwise known as the δ13C value.
δ13C values typically range between −10 and
−80 ‰, with abiogenic sources
closer to zero and biogenic sources showing more negative values. Initially,
we suggest that a δ13C difference of 10 ‰ is sufficient,
in order to differentiate between methane source types, based on this we
derive that a precision of 0.2 ppbv on 13CH4 retrievals may
achieve the target δ13C variance. Using an application of the
well-established information content analysis (ICA) technique for assumed clear-sky conditions, this paper shows that using a combination of the shortwave
infrared (SWIR) bands on the planned Greenhouse gases Observing SATellite
(GOSAT-2) mission, 13CH4 can be measured with sufficient
information content to a precision of between 0.7 and 1.2 ppbv from a
single sounding (assuming a total column average value of 19.14 ppbv), which
can then be reduced to the target precision through spatial and temporal
averaging techniques. We therefore suggest that GOSAT-2 can be used to
differentiate between methane source types. We find that large unconstrained
covariance matrices are required in order to achieve sufficient information
content, while the solar zenith angle has limited impact on the information
content.
Quantification of surface water volume changes in the Mackenzie Delta using satellite multi-mission data
Authors: Normandin Cassandra , Frappart Frédéric , Lubac Bertrand , Bélanger Simon , Marieu Vincent , Blarel Fabien , Robinet Arthur , Guiastrennec-Faugas Léa
Published: February 2018

Abstract. Quantification of surface water storage in extensive floodplains
and their dynamics are crucial for a better understanding of global
hydrological and biogeochemical cycles. In this study, we present estimates
of both surface water extent and storage combining multi-mission
remotely sensed observations and their temporal evolution over more than 15 years
in the Mackenzie Delta. The Mackenzie Delta is located in the northwest of Canada and is the second largest delta in the Arctic Ocean. The delta
is frozen from October to May and the recurrent ice break-up provokes an
increase in the river's flows. Thus, this phenomenon causes intensive floods
along the delta every year, with dramatic environmental impacts. In this
study, the dynamics of surface water extent and volume are analysed from 2000
to 2015 by combining multi-satellite information from MODIS multispectral
images at 500 m spatial resolution and river stages derived from ERS-2
(1995–2003), ENVISAT (2002–2010) and SARAL (since 2013) altimetry data. The
surface water extent (permanent water and flooded area) peaked in June with
an area of 9600 km2 (±200 km2) on
average, representing approximately 70 % of the delta's total surface.
Altimetry-based water levels exhibit annual amplitudes ranging from 4 m in
the downstream part to more than 10 m in the upstream part of the Mackenzie
Delta. A high overall correlation between the satellite-derived and in situ
water heights (R > 0.84) is found for the three altimetry missions.
Finally, using altimetry-based water levels and MODIS-derived surface water
extents, maps of interpolated water heights over the surface water extents
are produced. Results indicate a high variability of the water height
magnitude that can reach 10 m compared to the lowest water height in the
upstream part of the delta during the flood peak in June. Furthermore, the
total surface water volume is estimated and shows an annual variation of
approximately 8.5 km3 during the whole study period, with a maximum of
14.4 km3 observed in 2006. The good agreement between the total surface
water volume retrievals and in situ river discharges (R= 0.66) allows
for validation of this innovative multi-mission approach and highlights the high
potential to study the surface water extent dynamics.
Physically based approaches incorporating evaporation for early warning predictions of rainfall-induced landslides
Authors: Reder Alfredo , Rianna Guido , Pagano Luca
Published: February 2018

Abstract. In the field of rainfall-induced landslides on sloping covers, models for early warning predictions require an adequate trade-off between two aspects: prediction accuracy and timeliness. When a cover's initial hydrological state is a determining factor in triggering landslides, taking evaporative losses into account (or not) could significantly affect both aspects. This study evaluates the performance of three physically based predictive models, converting precipitation and evaporative fluxes into hydrological variables useful in assessing slope safety conditions. Two of the models incorporate evaporation, with one representing evaporation as both a boundary and internal phenomenon, and the other only a boundary phenomenon. The third model totally disregards evaporation. Model performances are assessed by analysing a well-documented case study involving a 2 m thick sloping volcanic cover. The large amount of monitoring data collected for the soil involved in the case study, reconstituted in a suitably equipped lysimeter, makes it possible to propose procedures for calibrating and validating the parameters of the models. All predictions indicate a hydrological singularity at the landslide time (alarm). A comparison of the models' predictions also indicates that the greater the complexity and completeness of the model, the lower the number of predicted hydrological singularities when no landslides occur (false alarms).
Convection-permitting regional climate simulations for representing
floods in small and medium sized catchments in the Eastern Alps
Authors: Reszler Christian , Switanek Matthew Blasie , Truhetz Heimo
Published: February 2018

Abstract. Small scale floods are a consequence of high precipitation rates in small areas that can occur along frontal activity and convective storms. This situation is expected to become more severe due to a warming climate, when single precipitation events resulting from deep convection become more intense (Super Clausius-Clapeyron effect). Regional climate model (RCM) evaluations and inter-comparisons have shown that there is evidence that an increase in regional climate model resolution and in particular, at the convection permitting scale, will lead to a better representation of the spatial and temporal characteristics of heavy precipitation at small and medium scales. In this paper, the benefit of grid size reduction and bias correction in climate models are evaluated in their ability to properly represent flood generation in small and medium sized catchments. The climate models are coupled with a distributed hydrological model. The study area is the Eastern Alps, where small scale storms often occur along with heterogeneous rainfall distributions leading to a very local flash flood generation. The work is carried out in a small multi-model (ensemble) framework using two different RCMs (CCLM and WRF) in different grid sizes. Bias correction is performed by the use of the novel Scaled Distribution Mapping (SDM) method. The results show, that for small catchments (