bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Chromium Content on Thermal Shock Cycle Resistance of (TiCr)N Hard Reactive Films
Authors: Dai Bu Shi , Zhang Jun
Published: June 2017

The (TiCr)N hard reactive films with 4 different Ti/Cr atomic ratios are prepared by using multi-arc ion plating. The Ti and Cr targets are used as cathodes in the co-deposition process. The high speed steel (HSS) specimens are adopted as substrate. The thermal shock cycle tests in air cooling (AC) way for the (TiCr)N films are carried out. The test temperatures are chosen as 600 °C and 700 °C, respectively. The changes of the surface compositions and morphology in the thermal shock cycle tests are investigated. The effects of Cr content in the (TiCr)N films, the temperature at which the thermal shock cycle tests are performed and the cycling times on the thermal shock resistance of the (TiCr)N films are discussed and analyzed in detail. The thermal shock behaviors of the (TiCr)N films show that the thermal shock cycling process of the (TiCr)N films consists of two stages, the steady-state oxidation stage with the increase of oxygen content at the early stage of thermal cycles, and, the instable oxidation stage with the oxidation aggravation and the occurrence of the surface cracks. The simple increase of Cr content in the (TiCr)N film does not improve the thermal shock resistance of the (TiCr)N films but easy to aggravate the surface oxidation process during the thermal shock cycles.
A Study on Mechanical and Tribological Behavior of Brake Pad Materials
Authors: Kumar Sanjeet , Kumar Deepak , Jain Jayant
Published: June 2017

Controlled friction and wear are the prime requirements of a braking system. The generation of wear debris depends on the brake materials properties, which in turn controls the tribological behavior. Present study deals with the performance evaluation and failure analysis of two commercial brake pads. Tribo Testing Rig (TTR) was used to evaluate the performance of brake. The tests were performed by making a tribo-pair of brake pad against the rotating disc with varying speed and pressure conditions. The wear response was quantified by mass loss, while the friction was measured in terms of coefficient of friction. Virgin and worn surfaces were analyzed using X-ray diffractometer (XRD), energy dispersive spectroscopy (EDAX) and Scanning electron microscope (SEM) to understand the wear and friction mechanisms. It was found that the type of constituents present in the brake-pad material and their spatial distribution plays an important role in controlling the wear and friction behavior. The high wear and friction was attributed to the presence of bulky particles of Fe and Si.
Tribological Study of Heat Treated AZ91 Alloy against Al6351 under Dry Conditions
Authors: Kumar Sanjeet , Jain Jayant , Kumar Deepak
Published: June 2017

AZ91 Mg alloy is one of the most suitable alloy of magnesium for automotive and aerospace applications. In this study, tribological evaluation of AZ91 Mg alloy is performed against Al6351 alloy under dry sliding condition. The load was kept constant for a range (0.05-0.2 m/s) of sliding velocities. This study can be seen as an initial attempt in the direction of employment of Mg alloy for a dynamic engine component. The experiments were conducted on the solution treated and peak aged AZ91 Mg alloy by making a tribo pair with Al6351 alloy on a pin on disc setup under dry condition. The AZ91 and Al6351 alloys were used as a pin and a disc (flat) materials, respectively. The samples were characterized using hardness tester, tribometer and SEM/EDS. The wear mechanisms were identified by analyzing the worn surfaces and wear debris using SEM.
Influence of Aluminum Nanoparticles Additives on Tribological Properties of Base Oil
Authors: Le Vu Nguyen Anh , Lin Jau Wen
Published: June 2017

This study investigates the influence of aluminum nanoparticles, oleic acid as dispersants, and rotational speed on the tribological behavior of a lubricant. The experiments are performed on a pin-on-disc tribotester at a normal force of 90 N and a rotational speed ranging from 150 rpm to 600 rpm. Both the aluminum nanoparticles and oleic acid are in concentrations from 0 to 1 wt% and are added to the SN150 base oil. The results revealed that the addition of aluminum nanoparticles and oleic acid to the base oil will lead to significant friction reduction and anti-wear properties. The coefficient of friction (COF) and wear rate decreased after an increase in the concentration of nanoparticles and oleic acid, and an optimum concentration level was exhibited in which both COF and wear-rate were lowest. The viscosity and temperature of the lubricant are also evaluated. Further, the topography of discs after performance of sliding test have been analyzed through the use of an optical microscope, a scanning electron microscope (SEM), and an energy dispersive spectrometer (EDS) in order to interpret the mechanisms of nanoparticle action used to prevent friction and subsequent wear.
Residual Stress/Strain Effect on the Bending Properties of the Cu/Al/Cu Clad Plate
Authors: Kim Yong Keun , Hong Sun Ig
Published: June 2017

One of the important issue in the production of the industrial scale Cu/Al/Cu clad plate is the evolution of residual stress/strain during rolling the stack of thick slabs into thin wide and long plates. In this study, the effect of residual stress/strain and annealing on the bend forming behaviors of Cu/Al/Cu clad composite were studied. Tensile strength of separated convex side Cu layer from the bent Cu/Al/Cu clad plate was observed 350MPa, smaller than that of concave side Cu-layer (380MPa). The lower strength and higher fracture strain in the convex side Cu layer is attributed to the presence of the compressive residual strain in the convex side. After heat-treatment at 380°C no pronounced interface debonding and separation between Cu and Al layers were noted, supporting a reliable interface bonding between Cu and Al. The ductility of Cu/Al/Cu clad plate was observed to be greater than that of Al, which can be explained by the co-deformation induced the interaction and constraint between bonded Al and Cu layers. The bend forming behavior of the bent Cu-Al-Cu clad composite was not greatly influenced by the residual stress/strain developed during rolling because of the thick Al layers with negligible residual stress between Cu.
Double-Channel Filter Based on the Structure of Two Symmetric Layers with Defects in One-Dimensional Photonic Crystals
Authors: Jian Bi Yuan , Wu Guang Bin , Wang Hong
Published: June 2017

Using 2×2 transfer matrix method, we numerically investigate a kind of structure in which two symmetric layers with defects are sandwiched in one-dimensional photonic crystals (PCs). The PCs are made of ordinary dielectrics and placed in the air. When a light beam is incident into PCs, the two resonant peaks can be achieved which constitute a couple of photonic channels. The transmittance of the resonant peaks can nearly reach up to 1. Furthermore, the tunability of the resonant peaks is discussed in detail, the results shows that the position of the resonant peak depending on the value of the incident angle. These properties can provide a theoretical basis for design of a new type of tunable double-channel photonic crystal filter.
Effect of Ni Plating on the Interfacial Stability of Multi-Layered Ni-Plated-Cu/Al/Ni-Plated-Cu Clad Composite
Authors: Kim Hyung Jin , Hong Sun Ig
Published: June 2017

In this study, electro nickel coating was applied and its effect on the interfacial stability and cracking behaviors were investigated in the multi-layered Ni-plated-Cu/Al/Ni-plated-Cu clad composite. Ni plating with 5μm thickness on the Cu sheet before cladding does not form a continuous layer between Cu and Al because of its low ductility. Ni layer covers the part of the Cu/Al interface. In the interface region without Ni layer, CuAl2, CuAl and Cu9Al4 were found to be formed after annealing whereas Al3Ni2 and Al3Ni were found to be formed in the interface region with Ni layer. After bending, interface crack developed initially in the interface region with plated Ni layer. On the other hand, the interface region with no Ni layer, no interface cracks were found to formed, suggesting that the bonding between Al and Ni is not strong enough. After interface crack formation, cracks developed in the Al layer, which may lead to the fatal fracture.
Studies of the Physical Properties of Cycloaliphatic Epoxy Resin Reacted with Anhydride Curing Agents
Authors: Kim Tae Hee , Kim Dae Yeon , Lim Choong Sun , Seo Bong Kuk
Published: June 2017

The preparation of high performance epoxy composites for industrial applications has been extensively researched. In this report, we study the change in physical properties and reaction kinetics between epoxy resin and curing agents of similar geometry. For the experiments, celloxide 2021P, an epoxy resin having low viscosity, was blended with three different curing agents: methylhexahydropthalic acid, methyltetrahydropthalic acid, and 5-norbornene-2, 3-dicarboxylic anhydride. The amount of 1, 2-dimethylimidazole catalyst was controlled, and the highest heat flow temperature (Tpeak) was observed at around 145 °C. The impact on reaction kinetics relative to the change in heating rate was studied with differential scanning calorimetry (DSC) for each of the curing agents. The glass transition temperature (Tg) of each composition was measured with a second DSC cycle. The prepared epoxy compositions were thermally cured in a metallic mold to provide pure epoxy resins without fillers. Finally, the flexural strengths of these resins were compared to each other. The authors believe that insights into choosing an appropriate epoxy binder are useful when it comes to the overall preparation of high performance polymer composites.
Crystallization and Thermal Degradation of Green Nanocomposites Based on Lignin Coated Cellulose Nanocrystals and Poly(Lactic Acid)
Authors: Boruvka Martin , Bĕhálek Luboš
Published: June 2017

Cellulose is almost inexhaustible source of raw material comprising at least one-third of all biomass matter. Through deconstruction of cellulose hierarchical structure can be extracted highly crystalline cellulose nanocrystals (CNC) with impressive properties. However, the main barrier in the processing of the nanocomposites based on CNC is their inhomogeneous dispersion and distribution in the non-polar polymer matrix. In this paper is this problem addressed by use of novel hydrophobic lignin coated CNC as a biobased nucleation agents in poly (lactic acid) (PLA) nanocomposites. These green nanocomposites based on natural plant derived substances have enormous potential to replace materials originated from non-renewable resources and show promise of providing degradation back into the environment when they are no longer needed. Resulted composites prepared by twin screw extrusion and injection moulding were characterized by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The addition of L-CNC (1, 2 and 3 wt. %) into PLA increased melt crystallization enthalpy and decreases the cold crystallization enthalpy. The degree of crystallinity (cc) increased from 5.6 % (virgin PLA) to 8.5 % (PLA/1-L-CNC), 10.3 % (PLA/2-L-CNC) and 10.7 % (PLA/3-L-CNC). The wide range of degradation temperatures of lignin coating has been observed starting at 100 °C.
Mechanical and Thermal Properties of Epoxy Composites Containing Amine-Modified Silica Nanoparticles
Authors: Lee Hye Ryun , Kim Moon Il , Na Hye Ryun , Lim Choong Sun , Seo Bong Kuk
Published: June 2017

Epoxy/silica composites were prepared using aminopropyl triethoxysilane (APTES)-modified silica nanoparticles in the sol state. Different sizes of silica particles were synthesized and they were applied into the epoxy/silica composites with different compositions. The mechanical and thermal properties of the composites were investigated and compared with those of pristine epoxy composite. The structure and morphology of the modified silica nanoparticles and epoxy/silica composites were analyzed using field emission scanning electron microscope. The flexural modulus and tensile strength of the epoxy/silica composites were investigated by universal test machine (UTM). Also, glass transition and thermal stability were investigated using thermomechanical analyzer (TMA). Sizes of silica particles in sol state were controlled by using different concentration of the accelerator. The tensile strength of epoxy/silica composites containing 20 wt% of 30 nm silica was found to be 37.98 MPa. In addition, the glass transition temperature (Tg) decreased with increasing silica particle sizes.
Morphology and Mechanical Properties of Poly(Lactic Acid) and Propylene-Ethylene Copolymer Blends: Effect of Organoclay Types
Authors: Wacharawichanant Sirirat , Ounyai Chaninthon , Rassamee Ployvaree
Published: June 2017

The effects of four types of organoclay on morphology and mechanical properties of poly(lactic acid) (PLA)/propylene-ethylene copolymer (PEC) blends were investigated. The ratio of PLA and PEC was 80/20 by weight and the organoclay content was 5 phr. The morphology analysis showed that the addition of all oganocaly types could improve the miscibility of PLA and PEC blends due to the decreased of the domain sizes of PEC dispersed phase in the polymer matrix. The tensile properties showed Young’s modulus of the PLA/PEC blends was improved after adding clay treated surface with 25-30 wt% trimethyl stearyl ammonium.
Effect of Plasticizers on Morphology, Mechanical Properties and Water Absorption of Wheat Gluten and Epoxidized Natural Rubber Blend
Authors: Hemsri Sudsiri , Bunsripirat Patthamas , Nakkarat Punnakit
Published: June 2017

Wheat gluten (WG) plastics are inherently brittle and sensitive to water. In this research, wheat gluten was blended with epoxidized natural rubber containing 50 mol% epoxide group (ENR-50) to improve flexibility and water resistance of WG plastics. Three plasticizers (i.e. glycerol (Gly), polyethylene glycol (PEG) and dioctyl phthalate (DOP) were used to enhance polymer chain mobility and process ability of WG phase in the blends. Differential scanning calorimetry (DSC) was used to evaluate plasticizing efficiency of plasticizers on WG. The DSC result revealed that an excellent plasticizer for WG was glycerol which could remarkably reduce glass transition temperature (Tg) of WG. Furthermore, effect of plasticizer types and contents (0, 10, 20 and 30wt% with respect to protein weight) on morphology, mechanical properties and water absorption of the WG/ENR blends was investigated. It was found that an enhancement in ductility and impact strength of the blends was observed with increasing plasticizer content. Among the plasticized WG/ENR blends, the glycerol-plasticized blend provided better homogenous morphology and superior results in tensile and impact properties. On the other hand, the Gly-plasticized WG/ENR blend showed a low water resistance compared with the blends plasticized with PEG and DOP as well as the unplasticized WG/ENR blend.
Studies on the Mechanism of Work Hardening of Austenitic High Manganese Steel Alloyed with Chromium and Vanadium
Authors: Duong Nam , Thi Chieu Le , Khanh Pham Mai
Published: June 2017

This article studies the mechanism of work hardening of austenitic high manganese steel alloyed with chromium and vanadium. The steel was annealed at 650°C before austenitizing at 1100°C, and then was quenched with water. We have observed that after the heat treatment, the size of austenite grain was small (1,950μm2 - level 6). The hardness of the steel was 223HB and the toughness was 115J/cm2. After impact loading, there was no martensite but twinning and sliding in the microstructure of the steel. The nano austenite was found in the microstructure. The steel was also hardened by small austenite grain and the carbide particles were finely dispersed in the microstructure.
The Use of Oil Palm Empty Fruit Bunches (OPEFB) Fibers as Partial Replacement for Imported Recycled Fibers
Authors: Khairul Hafizuddin A.B. , Rohaizu Roslan , Wan Rosli W.D.
Published: June 2017

Papermaking in Malaysia is basically based on recycled (secondary) fibers which are sourced from various parts of the world with prices depending on the quality of the fibers procured. The costs of paper production could possibly be reduced by using local fibers as partial replacement provided that the strength requirements are not compromised; and one such type is the oil palm fibers which are obtained as the by-product of the palm oil industry. This paper reports the use of the oil palm empty fruit bunch (OPEFB) fiber as a partial substitute in the production of corrugating medium. Both unbleached and totally chlorine free (TCF) bleached OPEFB pulps were mixed in different ratios with high quality recycled pulps which had been mechanically and chemically treated. Burst strength results indicate as high as 70% recycled pulp can be replaced by OPEFB pulps yet still having strength properties that are comparable with the industrial produced corrugating medium. Although the effect of bleached pulp is significant at high addition levels of more than 70%, the cost-energy balance will not be effective to use these bleached fibers, and furthermore the utilization of unbleached pulps also gave the same desired results. The use of the underutilized OPEFB fibers for replacement of imported recycled fibers without compromising the paper strength qualities could help the Malaysian paper industry in their quest for finding fiber alternatives.
Microwave-Ultrasonic Synergistic Extraction of Crude Se-Polysaccharides from Se-Enriched Tea
Authors: Wang Tao , Li Wen , Li Tong Xiang
Published: June 2017

Se-polysaccharides are organic Se-conjugated biological macromolecules with stronger biological activities than Se-free polysaccharides. Se-polysaccharides, as a kind of biological materials, can be extracted from Se-enriched tea and can increase the added value of tea production. Microwave–ultrasonic synergistic extraction exhibits the advantages of microwave and ultrasonic extraction and thus provides an economic and effective path for utilization of Se-polysaccharides. In this study, Se-polysaccharides were extracted from Se-enriched tea by microwave–ultrasonic synergistic method for the first time. The optimal condition was determined through single-factor experiment and L9(43) orthogonal experiment. Results showed that the optimal condition comprised the following: ratio of solvent to material of 20:1, microwave power of 250 W, extraction temperature of 60 °C, and extraction time of 210 s; under this condition, the extraction rate of Se-polysaccharides reached the maximum value of 4.56%. This study shows that microwave–ultrasonic synergistic extraction is an efficient technology for extracting Se- polysaccharides from Se-enriched tea.
Ex Situ UCG Model Experiments with Oxygen Enriched Air in an Artificial Coal Seam
Authors: Su Fa Qiang , Itakura Ken-ichi , Hamanaka Akihiro , Deguchi Gota , Sato Kohki , Kodama Jun-ichi
Published: June 2017

Underground Coal Gasification (UCG) demands precise evaluation of the combustion area in the coal seam. Especially, the monitoring of fracture activity in the coal seam and around rock is important not only for efficient gas production but also for estimation of subsidence and gas leakage to the surface. For this objective, laboratory experiments were conducted using the simulated UCG models. This paper also investigated gas energy for coal consumption, the production gas quantity and heat value, the application of oxygen element balance in the gasification reaction process, and the gas composition obtained in this study. During burning of the coal, temperatures inside the coal, contents of product gases and acoustic emission (AE) activities were monitored successively under the control of feeding gas (air/oxygen and steam) flow rate. Comparison of the temperature variation and accumulated AE event curves revealed a close correlation between them. The local change of temperature inside the coal induced fractures with AE. The AE activity was related closely to the local changes of temperature inside the model. The evaluation of gas energy recovery calculated from the obtained product gas provided a fair evaluation for the coal consumed, and the quantity of gas product and calorific value obtained from the UCG process.
In Situ Decomposition of Silicon Nitride Particles in Titanium Composite and its Mechanical Properties
Authors: Imai Hisashi , Yamabe Hiroyasu , Kondoh Katsuyoshi , Umeda Junko , Khantachawana Anak
Published: June 2017

Dependence of the mechanical properties of PM extruded titanium with the silicon nitride (Si3N4) on solid phase decomposition of Si3N4 was investigated. Si3N4 particles within Ti composite powder were decomposed during spark plasma sintering at 1223 K with 30 MPa pressure for 3.6 ks; and then, decomposition by-products of nitrogen and silicon atoms were defused into titanium matrix. The extruded Ti-1.0 mass% Si3N4 composite showed ultimate tensile strength (UTS) of 1139 MPa, and yield stress (0.2%YS) of 1065 MPa. UTS and 0.2%YS of P/M extruded Ti-1.0 mass% Si3N4 composite were 2 and 2.5 times compared to extruded pure Ti powder material, respectively. It was considered that the solid solution strengthening of both nitrogen and silicon originated from Si3N4 caused the high strength of PM extruded Ti-1.0 mass% Si3N4 composite.
Biodiesel Production from Jatropha oaxacana Oil by Reactive Vacuum Distillation: Optimization by Response Surface Methodology
Authors: Regalado-Méndez Alejandro , Mentado-Morales Juan , Peralta-Reyes Ever , Estrada-Vázquez Carlos , Martínez-Villa Gerardo , Cordero Mario E. , Zárate Luis G.
Published: June 2017

The application of Response Surface Methodology (RSM) and Central Composite Rotatable Design (CCRD) for modeling and optimization of the influence of three operating variables (mass of catalyst, MeOH/Oil molar ratio, and temperature) on performance of Reactive Vacuum Distillation (RVD) to increase biodiesel yield is discussed in this work. Changes in RVD performance during biodiesel production were evaluated by using RSM and CCRD. A mathematical equation to model biodiesel production by RVD was derived from computer simulation programming by applying a least squares method using MATLAB® v. R2016a. Predicted values were found to be in good agreement with experimental values (with R2 = 0.934). Optimal conditions for the production of ethyl esters were: Temperature: 31.2 °C, MeOH/Oil molar ratio: 5.65:1, and mass of catalyst: 0.1344 g.
Investigation of the Structural Properties of Amorphous Philippine Bentonite Clay and its Potential Use for Topical Applications
Authors: Olegario-Sanchez Eleanor , Felizco Jenichi Clairvaux
Published: June 2017

This study aims to characterize the Philippine natural bentonite from Mangatarem, Pangasinan for potential topical applications. Six samples were obtained from the mine site. Using the low angle region of their XRD patterns, initial mineralogical analysis of the samples was conducted. The presence of the 6.08° peak, which represents the presence of pure smectite material, was only observed in one sample, D2. The long range XRD pattern of the D2 bentonite sample confirmed montmorillonite as the main component. Other clay minerals such as hectorite and mordenite were also detected in small intensities. In the chemical analysis, Si and Al were the primary elemental components. However, the presence of high amount of Ca revealed that the sample is Ca-bentonite. Also present are other exchangeable cations such as Na+, K+, and Mg2+. To confirm their applicability for topical uses, the CEC, pH and presence of E. coli were determined. The CEC of the sample was 114.32 meq/100g, and the pH value was 7.1. Microbial test also confirmed the absence of E. coli. These tests all validate that the sample is safe and viable for topical applications.
Heavy Metal Removal from Wastewater of Palm Oil Mill Using Developed Activated Carbon from Coconut Shell and Cow Bones
Authors: Adeleke Abdul Rahman Oyekanmi , Abdul Latiff Ab Aziz , Daud Zawawi , Mat Daud Nur Falilah , Aliyu Mohammed Kabir
Published: June 2017

Palm oil mill efluent (POME) is the major industrial waste water in Malaysia and Indonesia. The processing of (POME) before discharge is a major challenge to researchers. In this study, the adsorption experiment of zinc ion from (POME) produced from the processed palm oil as primary treatment has been investigated using coconut shell and cow bone activated carbon. Experiments were conducted at a fixed initial concentration, contact time, shaking speed and at different adsorbent dosage to obtain optimum condition for the uptake of zinc ion from POME. The coconut shell carbon exhibited better removal efficiency than the cow bone powder. The results obtained at fixed condition of pH 7, contact time of 105 minutes, shaking speed of 150 rpm showed more than 90% uptake for both adsorbents. The result of the adsorption study was further analyzed using Langmuir and BET model to determine the experimental isotherm. The result showed that equilibrium data fitted better with BET model for coconut shell carbon and better with Langmuir model for cow bone powder. The result of the adsorption experiments showed that heavy metal of zinc can be sufficiently reduced on both coconut shell carbon and the cow bone powder. The morphology of both adsorbents was observed using the scanning electron microscope (SEM), the pore sizes of the adsorbents supported the uptake of zinc ion from the raw POME.
Preparation Process Optimization of the Solid Chlorine Dioxide as an Environmental Friendly Disinfectant for Drinking Water
Authors: Li Qun , Li Xiao Wen , Li Zi Chao , Zhao Xi Hui , Wang Yue , Liu Cai Hong
Published: June 2017

Disinfection is the last treatment process in the Drinking Water Treatment Plant. Chlorine dioxide (ClO2) is a widely used environmental friendly disinfectant which is employed in this process. The aim of this work was to optimize the reaction conditions and improve the formula of the solid chlorine dioxide disinfectant. Magnesium sulfate (MgSO4) and citric acid were employed as the stabilizer and activator, respectively. Sodium chlorite (NaClO2) and sodium bisulfate (NaHSO4) were used as the reactants. The concentration of chlorine dioxide was determined by the five-step iodometry method. The results showed that the percentage of chlorine dioxide have a relationship with the reaction temperature, reaction time, the mass ratio of NaClO2 and NaHSO4. The percentage of chlorine dioxide has a para-curve relationship with the reaction time. At 2.5 h, it reached the highest percentage of chlorine dioxide about 6.3%. And the optimal reaction temperature is 25°C under the nearly ideal state mass ratio of NaClO2:NaHSO4 =1:1.071. The formula is suggested to be a proper composition of the solid environmental friendly chlorine dioxide disinfectant.
Shear Failure of Patched Reinforced Concrete Beam without Web Reinforcements
Authors: Kristiawan Stefanus , Supriyadi Agus , Sangadji Senot , Wicaksono Hapsara Brian
Published: June 2017

Degradation of reinforced concrete (RC) element could lead to a reduction of its strength and serviceability. The degradation may be identified in the form of spalling of concrete cover. For the case of RC beam, spalling of concrete cover could occur at the web of the shear span due to corrosion of the web reinfocements. The shear strength of the damaged-RC beam possibly will become less conservative compared to the corresponding flexural strength with a risk of brittle failure. Patch repair could be a choice to recover the size and strength of the damaged-RC beam. This research investigates the shear failure of patched RC beam without web reinforcements with a particular interest to compare the shear failure behaviour of patched RC beam and normal RC beam. The patch repair material used in this research was unsaturated polyester resin (UPR) mortar. The results indicate that the initial diagonal cracks leading to shear failure of patched RC beam occur at a lower level of loading. However, the patched RC beam could carry a greater load before the diagonal crack propagates in length and width causing the beam to fail in shear.
The Analysis of Long-and-Short Concrete Column Structure under Horizontally Seismic Process Based on Finite Element Method
Authors: Wang Zhe Heng , Yan Xin Chi
Published: June 2017

Under seismic action, concrete column has some potential problems. Due to its complexity, long-and-short concrete column structure usually faces more dangers than common structure. In order to research its features, Autodesk Robot Structural Analysis Professional is used as software of finite element method. A model of staggered reinforced concrete structure is built. Also, a non-staggered structure is built as a control group. These two structures have the same hypothesis of mass, stiffness and load case, so as to simulate the level of seismic condition and study the features of two structures. The results show that: 1) the maximum stress in non-staggered structure is obviously greater than that in staggered structure. 2) bending moment values in the supports in staggered structure are less than those in non-staggered structure. These consequences show that reducing the location of part of beams properly can decrease the maximum stress and bending moment in supports effectively.
Damage Detection with FBG Sensors for Pre-Stress Concrete Girders
Authors: Lee Seong Cheol , Shin Kyung Joon , Kim Jae Min , Lee Hwan Woo
Published: June 2017

In this paper, possibility to detect damage on post-tensioned concrete girders was investigated through an experimental program with 6 m long specimens containing smart tendons where FBG (Fiber Bragg Grating) sensors were embedded. Total six specimens were fabricated and tested, and test variables were prestressing tendon’s profile and web thickness. All the specimens were subjected to 3-points loading, and they exhibited shear failure. Through the test, it was observed that tendon strains were successfully measured through FBG sensors regardless of the test variables. It was also observed that tendon strains within the pure span significantly increased while ones nearby the anchors beyond the pure span were constant. When the specimen was cracked, FBG sensors nearby cracks showed relatively drastic increase on tendon strain. Since strain variation along tendons cannot be detected by conventional equipment such as a load-cell, the test results indicated that actual tendon strains can be easily measured with FBG sensors. These results showed that FBG sensors can be useful to check whether prestressed concrete members were significantly damaged. In addition, it is expected that FBG sensors can be helpful on more reasonable maintenance of PSC girders.
Dynamic Characteristics Analysis of Long-Span Cable-Stayed Bridge with Steel Truss Stiffening Girder
Authors: Bai Bing , Guo Jing
Published: June 2017

With the development of transportation, more and more long-span floating system steel truss-stiffened cable-stayed bridges have been built. Due to the non-restraint in longitudinal direction, this kind of bridges possess very superior performance in the dissipation of vibration energy. On account of the characteristics above, the paper intends to discuss the dynamic behavior of this type of bridges. Based on a real structure design, the numerical simulation procedure of the vibration has been introduced. According to a series of assumptions, the dynamic 3D FEM model of the bridge is established firstly. Thereafter, the vibration characteristics of the model are evaluated. Results show that the longitudinal stiffness is relatively small in comparison to the torsional stiffness. The 1st order mode is longitudinal floatation of girders and pylons. But overall the bridge is still rather flexible.
Seismic Response Analysis of Reservoir Water-Gravity Dam-Foundation System
Authors: Wang Yu Yang , Liu Jun Yu , Ning Bao Kuan , Zhang Ping
Published: June 2017

The Scaled boundary finite element method and finite-infinite element method are used to model the system of reservoir water – gravity Dam - infinite foundation. The effect of the reservoir water and the infinite foundation on the seismic response of the dam system is analyzed. In the paper, taking the Koyna gravity dam as the research object, the dynamic water pressure on the upstream face of the dam is calculated by SBFEM. The finite-infinite element method is used to model the infinite foundation. Finally, the time history of seismic displacement and the response of the dam under different elastic modulus are evaluated. By comparing the displacement response of the infinite element model of different elastic modulus, the conclusion is drawn that the response of the dam is increased with the increase of the elastic modulus of the foundation. In addition, the calculated results are compared with those of the model with no-mass foundation. It shows that the results of the model considering the radiation damping of the foundation are less than that of the model with no mass foundation.
Finite Element Analysis of Constitutive Behavior of FRP-Confined Steel Fiber Reinforced Concrete
Authors: Gholampour Aliakbar , Ozbakkaloglu Togay
Published: June 2017

This study presents the analysis of the constitutive behavior of fiber-reinforced polymer (FRP)-confined steel fiber reinforced concrete (SFRC) using a newly developed concrete damage-plasticity approach. Finite element (FE) analysis is conducted based on Lubliner’s model. The new concrete damage-plasticity approach accurately incorporates the effects of the steel fiber volume fraction and aspect ratio, confinement level, concrete strength, and nonlinear dilation behavior of confined concrete. New failure surface and flow rule were established using the experimental database. In order to validate the damage-plasticity model, the predictions from the FE analysis are compared with both experimental results and predictions of an accurate existing model for FRP-confined plain concrete. The analysis results indicate that the proposed approach accurately predicts the compressive behavior of FRP-confined SFRC.
Properties and Ageing of Crumb Rubber Modified Bitumens
Authors: Dasek Ondrej , Hyzl Petr , Coufalik Pavel
Published: June 2017

The issue of reusing waste materials is becoming very current and also includes reusing used tires. One of the possibilities is using these tires for the production of crumb rubber, which is added as a modifying agent into paving bitumens. The paper compares properties of this special type of asphalt binder with properties of conventional binders. In order to test the rheological properties, needle penetration, softening point, dynamic viscosity, resilience and elastic recovery tests were performed. Emphasis was put on description of rheological behavior determined using dynamic shear rheometer with the effects of ageing assessed using RTFOT method. It was found that crumb rubber modified bitumens have a higher stiffness in comparison to both paving and polymer modified bitumens. Ageing of crumb rubber modified bitumens led to an increase of complex shear moduli and decrease of phase angles. Increasing the crumb rubber content in bitumen leads to smaller increase of complex shear modulus due to ageing. It demonstrates higher resistance against ageing.
Mechanical Properties of Unsaturated Polyester Resin (UPR)-Mortar and its Potential Application to Restore the Strength and Serviceability of Patched Reinforced Concrete Slab
Authors: Kristiawan Stefanus , Supriyadi Agus , Prokoso Ageng Bekti , Rahmi Siti
Published: June 2017

Degradation of reinforced concrete could occur in various forms including spalling of concrete cover as a result of reinforcement corrosion. The degradation would shorthen the service life of the reinforced concrete structure. Patch repair method may be employed to recover this type of degradation using a suitable patch repair material. The authors have developed a patch repair material made from unsaturated polyester resin (UPR)-mortar. In this paper, the mechanical properties of this material which includes compressive strength, elastic modulus, flexural strength and bond strength are highlighted. Comparisons are also made with the normal mortar to emphasize the superior properties of UPR-mortar. Based on these properties, the potential application of UPR-mortar for repairing damaged reinforced concrete slab is examined through finite element simulation. It is pointed out that the tensile stress intensity in the UPR-layer is reduced with a consequence of reducing a risk of cracking in the repair zone. In addition, the patching of damaged zone with UPR-mortar could minimize the deflection.
FWHM Calculation of Zircon Gem-Materials before and after Thermal Enhancement
Authors: Wattananurak Pilantana , Monarumit Natthapong , Chooyoung Rattanawalee , Won-In Krit , Chotikaprakhan Sutharat , Satitkune Somruedee
Published: June 2017

Zircon samples from Ubon Ratchathani, Thailand; Rattanakiri, Cambodia and Dak Nong, Vietnam change their color from light brown and reddish-brown to blue color after thermal enhancement at 1000 ๐C in reducing condition for 60 min. The high temperature is one of the factors for the zircon structure to recrystallize. The objective of this study is to describe the crystal structure of zircon samples before and after thermal enhancement. Zircon is a metamict mineral whose structure is destroyed by some trace elements. There are radioactive elements such as U and Th in the zircon structure. In this study, Raman spectroscopy was used to analyze the molecular vibration in zircon structure before and after thermal enhancement. As a result, the Raman spectra of zircon samples after thermal enhancement show the Raman shift at peak position of V3(SiO4) stretching around 1008cm-1to higher wavenumber concerning to the full width at half maximum (FWHM) values calculated by PyMCA software. The results could be summarized that the metamict zircon will be recrystallized to the crystalline zircon after thermal enhancement. The advantage of this study is about the identification of zircon before and after thermal enhancement.
A Study on the Welding Line Strength of Composite Parts with Various Venting Systems in Injection Molding Process
Authors: Minh Pham Son , Trung Do Thanh , Uyen Tran Minh The , Nhan Phan The
Published: June 2017

The welding line characteristics of injection molded parts with various venting systems were researched in this paper under the tensile tests of ISO 527. A mold was designed in such a way that specimens with and without a venting system can be developed separately. Both PA66 and PA66 + 30%GF materials were used in this study. Without the venting system, results showed that the weld line strength was only increased when the injection pressure varied from 0.9 MPa to 1.1 MPa, if continuously increasing the injection pressure, the weld line strength will get the negative effect. When the venting system was used, the decrease of the weld line strength with the high injection pressure was eliminated. With the use of 1.3 MPa injection pressure, when increasing the venting gap from 0.02 mm to 0.10 mm, the weld line strength varied from 10.45 MPa to 11.4 MPa with the PA66 material and from 30.8 MPa to 32.95 MPa with the PA66 + 30%GF material. With the case of without venting system, the air trap at the microstructure of weld lines was clearly observed. This trouble was removed when the venting gap value of 0.10 mm was used.
Modelling Kerf Width in WEDM Titanium Alloy Using Response Surface Methodology
Authors: Saedon J.B. , Jaafar Norkamal , Yahaya Mohd Azman , Mohamad Nor Nor Hafiez , Husain Hazran
Published: June 2017

Wire electrical discharge machining is a material removal process of electrically conductive materials by the thermo-electric source of energy. This kind of machining extensively used in machining of materials with highly precision productivity. This work presents the machining of titanium alloy (TI-6AL-4V) using wire electro-discharge machining with brass wire diameter 0.5mm.The objective of this work is to study the influence of three machining parameters namely peak current, pulse off time and wire tension to kerf width followed by suggesting the best operating parameters towards good machining characteristics. A full factorial experimental design was used with variation of peak current, feed rate and wire tension, with results evaluated using analysis of variance techniques (ANOVA). The test array was further extended to allow for the implementation of Response Surface Methodology (RSM) analysis in order to develop first and second order models for the prediction of kerf width response. The results showed that average percentage error between the predicted and experimental value for kerf width models was less than 2%.
Effect on Hardness and Microstructures of Rail Joint with Ultra-Narrow Gap Arc Welding by Post Weld Heat Treatment
Authors: Gong Lian , Zhu Liang , Zhou Hong Xiang
Published: June 2017

U71Mn rails were welded by ultra-narrow gap welding with constrained arc by flux strips，then normalizing treatment and stress relief annealing were performed for the joints. Another sample with no heat treatment, was studied in comparison. The effect of post weld heat treatment on the hardness and microstructure of rail joint were studied by scanning electron microscope (SEM) and microhardness test. The test results showed that normalizing treatment can improve the hardness of weld seam and base metal, and stress relief annealing couldn’t improve the hardness of joints obviously.
Evaluation of Surface Quality and Signal Characteristics in Milling Process of Al7075-T651
Authors: Hwang M.C. , Koo Joon Young , Choi Yong Ki , Kim Hyun Jung , Kim Jeong Suk
Published: June 2017

Recently, as the automotive and aerospace industry research has focused one weight lightening, the use of functional aluminum alloys has been increasing. Aluminum alloys are effective materials because of their high specific strength and high stiffness ratio. However, machining deformation and heat deflection can occur depending on the machining type. Owing to these difficult-to-cut characteristics, it is necessary to monitor the machined surface quality of aluminum alloys. In this paper, we study the correlation between surface quality, namely burr formation and surface roughness, related to cutting parameters and signals obtained from multiple sensors. The output signals are measured by an acoustic emission (AE) sensor and an accelerometer and are analyzed in the signal frequency domain. By using the wavelet transform of analyzed signals, we determine the correlation between surface quality and signals. Based on this investigation, a surface quality monitoring system can be suggested.
Shear Assessment of Concrete Bridge Deck Slabs
Authors: Vida Radoslav , Halvonik Jaroslav
Published: June 2017

The transitions from old STN standards to Eurocode standards brought several problems into bridge design and assessment. Shear reinforcement is now often required even in concrete members, which were previously allowed to be built without it. Moreover, assessment of existing reinforced concrete bridge structures often shows their insufficiency in shear capacity, which means that they should be strengthened or replaced. Work on new generation of Eurocodes is currently in progress and current model for shear assessment should be replaced by a new (and more precise) one. This paper deals with the problem of shear assessment of concrete bridge according to current standard and also according to the new shear models that are under consideration.
The Strengthening of Reinforced Concrete Structures
Authors: Stepanek Petr , Laníková Ivana , Simunek Petr , Sulak Pavel
Published: June 2017

The contribution deals with a method of strengthening reinforced concrete structures. It focuses on the use of non-bonded steel tendons for beams and plates. The strengthening of columns with the help of steel bandages is discussed too. The behaviour of the strengthened items is described, as well as the practical design issues involved. The article also provides information on practical experience gained during the application of the strengthening method.Other possible applications for the strengthening method are discussed, such as the use of materials based on FRP (fibre reinforced polymer), and especially those based on glass.
Petrography, mineralogy and initial fluid inclusion results from the Jason, Tom, and Nidd SEDEX deposits, Macmillan Pass District, Yukon
Authors: Magnall J M , Gleeson S A , Paradis S , Blamey N J F
Published: June 2017

Sediment-hosted base metal mineralization in the Selwyn Basin occurs during 3 time intervals in the Cambrian, Silurian and Late Devonian, coeval with magmatic episodes. At Macmillan Pass, the Tom, Jason and Nidd showings are hosted by Upper Devonian sediments and
have well preserved vent complexes beneath overlying bedded sulphides (Tom, Jason).
Core was sampled from the vent complexes at Tom, Jason, and Nidd. Detailed petrography (reflected and transmitted light and cathodoluminescence), was conducted to characterize the mineralogy within the vent complex, and the relationship of fluid inclusion bearing mineral phases to base metal
sulphides. Microthermometry (Tom and Nidd) and bulk incremental fast scan gas mass spectrometry (Nidd) was performed on fluid inclusion samples. Carbon, oxygen and sulphur isotopes were analysed on mineral separates to determine the source of these components in each system.
The petrography indicates that for all three localities, fluid flow in the vent can be split in two distinct stages. Stage 1 is dominated by extensive stock-work style iron carbonate veining, along with destructive carbonate and pyrite alteration. Base-metal sulphides are deposited during Stage 2,
in association with a volumetrically minor gangue assemblage (siderite, quartz ± barite, barytocalcite and quartz). Initial fluid inclusion results indicate the presence of a CO2-bearing assemblage at Nidd, which has preserved evidence of phase immiscibility. The N2-Ar-He bulk composition of
these samples suggests the involvement of a deep calc-alkaline magmatic reservoir. Microthermometric results from Tom indicate the presence of low (120-130°C) and intermediate (170-235°C) temperature fluids; only one salinity measurement was obtained from the intermediate temperature
fluid, which yielded a value of 7.9 wt.% NaCl. Delta-34S (VCDT) values have a broad range from -12.6 permille to 20.5 permille, and two sphalerite-galena pairs suggest equilibrium fractionation may have occurred between 366-388°C; delta-13C (V-PDB) have a restricted range from -0.5 permille
to -8.6 permille, apart from two groups of outliers that are either highly negative (-20 permille and -12.4 permille) or highly positive (13.3 permille and 14.3 permille); delta-18O (V-SMOW) range between 13.6 permille to 20.5 permille.
Ndembu cultural liminality, terrains of gender contestation: Reconceptualising Zambian Pentecostalism as liminal spaces
Authors: Kaunda Chammah J.
Published: June 2017

In this article, I demonstrate how Capital Christian Ministries International has been conceptualised as ecclesiastical spaces for de-gendering. I have utilised symbolic imagination within the Ndembu cultural liminality as theoretical framework in theological studies. I have argued that the initiates in the liminal spaces subverted social normative through the process of un-gendering. The article concludes by arguing that reclaim and reconstitute ecclesia spaces as liminal spaces have potential to promote gender emancipation within African Christianity.