bluuebunny/crossref_metadata_2025 huggingface dataset:
Solidification of Aluminum Copper Alloy during Twin Roll Strip Casting
Authors: Hussain Zuhailawati , Nasir Laila Masrur Mohd , Abu Seman Anasyida , Dhindaw Brij Kumar
Published: August 2014

Twin roll casting is an innovative route to produce thin metal strip directly from the melt. In this paper, solidification characteristics in roll strip cast aluminum alloys is described. Al-Mg-Si alloy was melted in a crucible and poured to stainless steel roller. The roll was connected to a driving motor which the rotation speed can vary from 10 rpm to 100 rpm. During this process, the melt was solidified to form a strip. A specimen of 50mm was cut from the cast strips. The strip was characterized for the thickness, hardness and microstructure. Variation in hardness, microstructure of the produced trip is explained as a comparison to normal casting.
Phase Studies in WC-Stainless Steel AISI 347 Hardmetal System with Graphite Addition
Authors: Hussain Zuhailawati , Salleh Emee Marina , Trung Tran Bao , Ahmad Zainal Arifin
Published: August 2014

In this study, WC-stainless steel AISI 347 hardmetal system was produced to replace WC-Co hardmetal which uses the expensive, toxic and depleted resource Co. WC, stainless steel AISI 347 and graphite powder mixture were milled in a planetary mill under argon atmosphere using a stainless steel container and balls. Carbon was added in amounts ranging from 0 wt% until 4 wt% into the composition to avoid unwanted η (Fe3W3C) phase. As-milled powder was compacted at 300 MPa and sintered in a tube furnace at 1350°C. ɳ phase was detected in compositions with 0 and 1 wt% C addition. For 2 wt% C addition, no η (Fe3W3C) phase formation was identified. However, the η phase was detected for compositions containing 3 and 4 wt% C. Maximum hardness was achieved due to the absence of η phase.
Effect of Different Thickness of Core Layer on Tensile Properties of Laminated Natural Rubber Latex Film
Authors: Md Sidek Mufidah , Rashid Azura A. , Azahari Baharin
Published: August 2014

Laminated natural rubber latex with cleaning agent and waste latex compound was prepared by arranging half-cured latex sheets with various thicknesses of core layer then moulding using hot press according to the Rheometer graph. Laminated layers consist of outer layer (natural rubber latex films with cleaning agent) and core layer (waste natural rubber latex film). The core layer and outer layer are prepared through casting method with different thickness. For core layer, three different thickness of film is cast and for outer layer the thickness is control. The aim of this paper is to study the effect of different thickness of core layer and the different molding temperature on tensile and swelling properties of laminated films. The tensile test was carried out to acquire good interfacial adhesion between the laminates films. The fractured surface morphologies were carried out using digital microscope (Dino-Lite) to understand the interfacial interaction between core and outer layer of the films. The use of NRL lamination films with NRL waste will contribute to novel materials for as mould cleaning product with green and easier cleaning compare to conventional cleaning process.
Utilization of Sludge from Sidoarjo Mudflow for Zeolite Synthesis
Authors: Salim Chris , Prastomo Niki , Shao Yan , Hinode Hirofumi
Published: August 2014

Sidoarjo mudflow occurred in 2006 has been causing major environmental problems in a wide area surrounding the region. The utilization of the sludge from this mudflow as useful materials is a potential solution to this problem. In this study, we proposed a hydrothermal treatment method to convert the silica-rich sludge into zeolites useful as adsorbent for inorganic pollutants such as heavy metals. Prior to the hydrothermal treatment, the sludge was contacted with NaOH solution in a teflon vessel. During the hydrothermal treatment, the mixture was subjected to increasing temperature for a certain period of time. After hydrothermal treatment, the solid phase was filtered, washed thoroughly until neutral pH and dried. In this study, we evaluated the effect of NaOH concentration and hydrothermal treatment temperature on the type of zeolite formed. The surface morphology and composition of prepared zeolite was characterized by SEM-EDS while the type of zeolite was determined by XRD analysis. Preliminary study of the adsorption ability of the zeolites towards metal ions was carried out by CEC measurement using sodium acetate method.
Effect of Needle Punching Direction on Nonwoven Fiber Mat to the Mechanical Properties of Kenaf Reinforced Epoxy Composites Produced by Vacuum Assisted Resin Transfer Molding
Authors: Ariawan Dody , Ishak Zainal Arifin Mohd , Taib Razaina Mat , Ahmad Thirmizir Mohd Zharif , Phua Y.J.
Published: August 2014

This study evaluates the performance of nonwoven kenaf mat reinforced epoxy that was fabricated by vacuum resin transfer molding method. Kenaf mats were formed by carding and needle punching technique at 50 cm2 sticthing density and 1.5 cm penetration depth. The specimens were prepared from different volume fraction of kenaf mat and epoxy resin, which consist of 18% kenaf mat/ 82% epoxy resin and 27% kenaf / 73% epoxy resin. Tensile and compression properties were studied at 0o, 45o and 90o needle punching direction. The tensile properties increased with the increase of composites volume fraction and were decreased with the increase of needle punching direction degree. On the other hand, the compression properties of composites were reduced with the increase of volume fraction and needle punching direction degree. The composites properties were affected by the orientation and interlocking of fiber caused by needle penetration in direction of depth and movement direction.
Crytallization and Properties of SiO2-Al2O3-K2O-ZrO2 Glass-Ceramics for Dental Applications
Authors: Mohd Nurddin Siti Mazatul Azwa Saiyed , Selamat Malek
Published: August 2014

The aim of the study was to investigate the influence of ZrO2 on the crystallization and properties of leucite phase from K2O -Al2O3- SiO2 glass-forming melts. A starting glass composition of weight %; 60.7-63.2% SiO2, 16.6% Al2O3, 11.6% K2O, 5.10% Na2O, 2.5-5.0% ZrO2, 0.5% TiO2 and 0.5% LiO2 was melted in an electric furnace, followed by quenched in cool water to produce glass frit. Malaysian silica sand from Terengganu was used as the SiO2 source. The glass powders were ball milled and compressed to form 13mm diameter discs using cool isostatic pressing. The discs were sintered at 650°C, 700°C, 750°C, 800°C and 850°C for 1 hour and characterised using X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). The results indicate that the amount of ZrO2 additive is one of the key factors controlling of leucite crystallization. The properties of sintered disc specimens were studied using three point bending, diametral and Vickers microhardness test. The results showed that the mechanical properties of leucite glass-ceramics increased as the amount of ZrO2 was increased.
Effect of Annealing on the Properties of SnSe Film Prepared by Thermal Vacuum Evaporation in the Presence of Argon Gas
Authors: Sabli Nordin , Talib Zainal Abidin , Wan Mahmood Mat Yunus , Zainal Zulkarnain , Hilal Hikmat S. , Husin Mohd Shahril
Published: August 2014

The differences in structural, compositional and photoelectrochemical properties for SnSe films annealed at different temperatures, under nitrogen atmosphere, were studied. Annealing the film electrode significantly improved its crystallinity but lowered its photoresponse. The photoresponse lowering was thus attributed to lowering in the defect concentrations.
Ionic Transport and Electrochemical Properties of PMMA-Based Gel Polymer Electrolytes for Magnesium Batteries
Authors: Zainol Nurul Husna , Mohd. Halizan Mohd. Zharfan , Chong Woon Gie , Osman Zurina
Published: August 2014

Poly (methyl) methacrylate (PMMA)-based gel polymer electrolytes (GPEs) containing magnesium triflate, Mg (CF3SO3)2 salt were prepared using solution casting technique. Different concentrations of Mg (CF3SO3)2 ranging from 5 wt.% to 30 wt.% have been added into a mixture of ethylene carbonate (EC) and propylene carbonate (PC) with a fixed mass ratio of 2:1. These free-standing GPE films were characterized using electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV) and cyclic voltammetry (CV). The highest ionic conductivity of 1.27 x 10-3 S cm-1 is obtained from the GPE film containing 20 wt.% of Mg (CF3SO3)2 salt. The electrochemical window stability has been found in the range of-2.5 V to 2.5 V for the highest conducting GPE film. This value is considerably high enough for the GPE film to be used as electrolyte in magnesium rechargeable batteries.
Carbon Dioxide Capture at Various Temperatures Using Ca(OH)2 Sorbent Fabricated by Sol-Gel Route in Ethanol Media
Authors: Mohd Daud Farah Diana , Sreekantan Srimala , Mohamed Abdul Rahman
Published: August 2014

Carbon dioxide (CO2) is considered to be the main greenhouse gas contributing to global warming and climate change. Therefore, the present paper investigates the CO2-capture performance of synthesized calcium hydroxides, Ca(OH)2 sorbent at different temperatures which are 350, 450, 550 and 650°C. The CO2 adsorption of the materials synthesized was studied in a thermo-gravimetric analyzer (TGA). The CO2 adsorption temperature strongly influenced the capture performance of the absorbent. The Ca(OH)2 sorbent are prepared by hydrolysis of calcium alkoxides, NaOH as precipitating agent and mixed solvent of ethanol with deionized (DI) water as medium at 35°C. X- ray diffraction (XRD) result showed 40 nm crystallite size of Ca(OH)2 hexagonal crystal structures. The Ca(OH)2 particle size and morphological properties before and after CO2 adsorption are studied by Field Emission Scanning Electron Microscopy (FESEM). The FESEM image indeed showed the rod like shape of Ca(OH)2 structures with rod length increased from 765 to 893 nm while the diameter is between 140 to 160 nm. When Ca(OH)2 sorbent adsorbed CO2, the structures are rigid interconnected each others like a lump shaped. The prepared Ca(OH)2 sorbent possesses a great potential to capture CO2 when increased temperature. Nevertheless, at intermediate temperatures (350-450°C), Ca(OH)2 sorbent still demonstrates a higher CO2 capture capacity than other intermediate temperature adsorbents such as layered double hydroxides (LDHs), lithium zirconates (LiZrO3) and hydrotalcites.
Energy Bandgap Engineering of ZnO Using Impurity Elements for Solar Cell Applications: A DFT Study
Authors: Bakhtiar Ul Haq , Ahmed Rashid , Shaari A. , bin Yaacob Muhammad Zaki
Published: August 2014

As a transparent conducting oxide, Cd:ZnO system is considered potential candidate for optoelectronic applications alternate to Al:ZnO. However instability issue of the Cd:ZnO system is under debate. Here we investigate effect of Cd impurities on physical properties of ZnO in wurtzite (WZ) as well as zincblende (ZB) geometries. Density functional theory (DFT) based full potential linearized augmented plane wave plus local orbital FP-L(APW+lo) method has been adapted for these investigations. To calculate the total energy of the system, exchange correlation energy term is evaluated at the level of GGA. For the more realistic band gap calculation, GGA in addition to mBJ exchange potential has been employed. From our calculations, it is observed, Cd:ZnO is more stable in ZB structure than that of WZ. The Cd substitution ZnO has a tendency to convert the hexagonal geometry into cubic. It is also observed, doping of the Cd impurities strongly influence the electronic structures resulting into the narrowing energy band gap.
Growth and Characterization of (100) and (111) 3C-SiC Thin Film for MEMS Capacitive Pressure Sensor for Extreme Environments
Authors: Marsi Noraini , Burhanuddin Yeop Majlis , Hamzah Azrul Azlan , Mohd-Yasin Faisal
Published: August 2014

The (100) and (111) crystalline cubic silicon nitride (3C-SiC) thin films have been epitaxially deposited on (100) silicon substrate with the thickness of 0.5 µm and 1.0 µm. The effects of the different growth of 3C-SiC are considered as the most critical factor in determining the mechanical properties by comparing with bulk value such as Young’s modulus (~455 GPa) and hardness (~42 GPa). This paper evaluates the mechanical characteristic of the 3C-SiC-on-Si wafers to improve the 3C-SiC thin film quality. The aim is to employ the thin film as the flexible diaphragm in the MEMS capacitive pressure sensor for extreme environment. The surface morphology of thin layer of grown 3C-SiC wafers are characterized by X-ray diffraction (XRD), Infinite Focus Microscopy (IFM), scanning electron microscopy (SEM) and nano-indentation test. The results show the superior mechanical strengths of both (100) and (111) 3C-SiC thin films over (100) Si. To conclude, these results show that (100) and (111) 3C-SiC are indeed high quality thin film mechanically compare to (100) Si thin film, and is suitable to employed as the flexible diaphragm of the MEMS capacitive pressure sensor for extreme environments.
Post-Deposition Annealing in Nitrous Oxide Ambient of RF-Magnetron Sputtered Y2O3 Film on Silicon Substrate
Authors: Quah Hock Jin , Cheong Kuan Yew
Published: August 2014

In this work, effects of post-deposition annealing (PDA) time (15, 30, and 45 min) in nitrous oxide ambient on Y2O3 film deposited on Si substrate using RF-magnetron sputtering have been systematically studied. Y2O3/Si system subjected to PDA time at 15 and 30 min has demonstrated a negative flatband voltage shift but a change to positive flatband voltage shift was observed when PDA time was prolonged to 45 min. The shift from negative to positive flatband voltage with enhancement of PDA time could be related to the accumulation of nitrogen in the Y2O3 gate that acted as negatively trap charge. It was perceived that sample subjected to PDA time at 30 min has demonstrated the best leakage current density-breakdown voltage (J-VB) characteristic. A correlation between the J-VB characteristics with effective oxide charge, slow trap density, interface trap density, and total interface trap density has been discussed.
Effects of Post-Deposition Annealing Time on Metal-Organic Decomposed Lanthanum Cerium Oxide Film Spin-Coated on Si Substrate
Authors: Lim Way Foong , Lockman Zainovia , Cheong Kuan Yew
Published: August 2014

Metal-oxide-semiconductor characteristics of MOD-derived lanthanum cerium oxide (LaxCeyOz) film deposited on n-type Si substrate have been studied. Post-deposition annealing of the oxide was performed in argon atmosphere for a dwell time, ranging from 15 to 120 min at a fixed temperature of 400°C. Results demonstrated presence of positively charged oxygen vacancies in all of the oxides post-deposition annealed for different dwell time. Acquisition of the lowest effective oxide charge as well as the lowest interface trap density and total interface trap density in oxide annealed for 120 min has led to the attainment of the highest breakdown voltage, surpassing other oxides.
Synergetic Effect of In and Ag Co-Doped ZnS for Enhanced Photocatalytic Hydrogen Evolution under Visible Light Irradiation
Authors: Kimi Melody , Yuliati Leny , Shamsuddin Mustaffa
Published: August 2014

In and Ag co-doped ZnS photocatalysts were successfully prepared by hydrothermal method to extend the light absorption of ZnS to the visible light region. The concentration of In was constant while for Ag was varied to optimize the photocatalytic activity. The In and Ag co-doped ZnS photocatalysts showed smaller band gap energy compared to single doped In (0.1)-ZnS and undoped ZnS. The photocatalytic activity of In and Ag co-doped ZnS photocatalysts was evaluated from the amount of hydrogen produced. The hydrogen evolution rate from aqueous solution containing Na2SO3 and Na2S as sacrificial reagent under visible light irradiation obtained from In and Ag co-doped ZnS is higher compared to the single doped In (0.1)-ZnS when optimum amount of Ag dopant was added. The highest photocatalytic activity is observed for In (0.1),Ag (0.01)-ZnS with hydrogen production rate of 26.82 μmol/h. The higher performance of this photocatalyst is ascribed to the extended visible light absorption, efficient charge separation as well as improved electron transfer associated with synergistic effect of appropriate amount of In and Ag co-doped ZnS.
Silicon Based Thermoelectric Cells with Built in Solar Cells and CNT Composite Based Thermoelectric Cells for Measurement of Gradient of Temperature
Authors: Karimov Khasan S. , Abid Muhammad , Yew Cheong Kuan , Ahmed Nisar , Bashir Muhammad Mehran , Abbas Syed Zameer
Published: August 2014

Thermoelectric cells and Solar cells are source of harvesting energy from heat and light respectively. In this study both are fabricated on a single cell using n-Si and p-Si single crystal strips.Later, temperature gradient cells are also fabricated . The fabricated Phtoto-thermoelectric cells and Temperature gradient celss are investigated, showing improvement in seebeck effect.
The Effect of Hydrothermal Reaction Time on Formation of AuNPs by Sacrificial Templated Growth Hydrothermal Approach
Authors: Ng Soo Ai , Khairunisak Abdul Razak , Cheong Kuan Yew , Ooi Poh Choon , Aw Kean Chin
Published: August 2014

This work describes the formation of gold nanoparticles (AuNPs) by using the sacrificial template growth hydrothermal method. AuNPs was grown on Aluminum/ polymethylsilsesquioxanes (PMSSQ) /Silicon substrates. Sputtered Al was used as a sacrificial template. The effect of hydrothermal reaction time on AuNPs properties was investigated for 1, 2, 3 and 4 hours. Properties of AuNPs were studied by using Field-Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD) and Semiconductor Characterization System (SCS). This approach allows the formation of AuNPs directly on the substrates. XRD analysis proved that Al template was removed during hydrothermal reaction. This approach allows the formation of AuNPs directly on the substrates. The number of AuNPs increased with increasing hydrothermal reaction time. However, longer than 1 hour reaction time, AuNPs tend to grow in clusters that could be due to unintended aggregation and agglomeration caused by self-association of the AuNPs. I-V characteristics showed hysteresis properties that indicated charge storage capability of AuNPs embedded in PMSSQ. AuNPs grown in 1 hour hydrothermal reaction produced the best memory properties due to well distribution of isolated AuNPs as observed in SEM image with the lowest abrupt current of 2.4 V.
Fabrication of Gold Nanoparticles on Multiwalled Carbon Nanotubes Nanohybrids
Authors: Alias Siti Hajar , Sondig Sydwel Syron Sondig , Md Jani Abd Mutalib , Yazid Hanani
Published: August 2014

A nanostructured hybrid consisting of a high-density and uniform assembly of gold nanoparticles (AuNPs) on multiwalled carbon nanotubes (MWCNTs) is always desired and demanded in various applications. However, a simple, cost effective and highly efficiency method is required in the fabrication of MWCNTs-AuNPs nanohybrids. This study introduces a method where MWCNTs were functionalizing with nitric acid (HNO3) and sulphuric acid (H2SO4) in ratio of 1:3 v/v by using ultrasonication. These functionalized MWCNTs served as substrates for gold nanoparticle deposition. Later, it was pre-mixed with tri-sodium citrate (Na3C6H5O7.2H2O), next it was reacted with nobel metal (AuNPs) via the addition of chloroauric acid (HAuCl4) at various pH. When HAuCl4 was added to the reaction system, Au3+ was directly reduced at the surface of the MWCNTs and gold nanoparticles were assembled along the MWCNTs. Fourier Transform Infrared (FTIR), Thermogravimetric Analysis (TGA), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray (EDX) analysis and dispersion test were used to characterize the MWCNTs/AuNPs nanocomposites. The fully functionalized MWCNTs using acid oxidation at 4 hour using ultrasonication were used in synthesis of nanohybrids, and the optimum gold yield on MWCNTs obtained at pH 4. Compared to other methods, these procedures require low temperature without involving the need of any catalyst or surfactant which results in a simple and efficient method for fabrication of gold nanoparticles on carbon nanotubes.
Effect of Applied Voltage on the Formation of Self-Organized Iron Oxide Nanoporous Film in Organic Electrolyte via Anodic Oxidation Process and their Photocurrent Performance
Authors: Rozana Monna , Azhar Mustaffa Ali , Anwar Dede Miftahul , Kawamura Go , Khairunisak Abdul Razak , Matsuda Atsunori , Lockman Zainovia
Published: August 2014

Anodisation of iron foil was done to produce anodic film with nanoporous structure. The effect of anodic voltage on the morphology of the anodic oxide formed was investigated. Anodic film formed on iron foil anodised at 10 V is rather compact no obvious pores. Pores can be detected on oxide anodised at 30 V despite not very uniform. For foil anodised at 50 V, 1.8 µm thick anodic layer which consisted of uniform circular pores is observed. This film was then annealed at 450°C for 3 h in air as to induce crystallinity. The annealed nanoporous film exhibits a light illuminated photocurrent of 0.45 mA in 1 M NaOH + H2O2 solution.
Three Dimensional Printing of Titanium for Bone Tissue Engineering Applications: A Preliminary Study
Authors: Guneta Vipra , Wang Jun Kit , Maleksaeedi Saeed , He Ze Ming , Wong Marcus Thien Chong , Choong Cleo
Published: August 2014

One of the main goals of bone tissue engineering is the development of scaffolds that mimic both functional and structural properties of native bone itself. This study describes the preliminary work carried out to assess the viability of using three dimensional printing (3DP) technology for the fabrication of porous titanium scaffolds with lowered modulus and improved biocompatibility. 3DP enables the manufacturing of three dimensional (3D) objects with a defined structure directly from a Computer Aided Design (CAD). The overall porosity of the 3D structures is contributed by the presence of both pores-by-process (PBP) and pores-by-design (PBD). This study mainly focuses on the PBP, which are formed during the sintering step as the result of the removal of the binding agent polyvinyl alcohol (PVA). Sintering temperatures of 1250oC, 1350oC and 1370oC were used during the fabrication process. Our results showed that by varying the binder percentage and the sintering temperature, pores with diameters in the range of approximately 17-24 μm could be reproducibly achieved. Other physical properties such as surface roughness, porosity and average pore size were also measured for all sample groups. Results from subsequent cell culture studies using adipose tissue-derived mesenchymal stem cells (ASCs) showed improved attachment, viability and proliferation for the 3DP titanium samples as compared to the two-dimensional (2D) dense titanium samples. Hence, based on our current preliminary studies, 3DP technology can potentially be used to fabricate customized, patient-specific metallic bone implants with lowered modulus. This can effectively help in prevention of stress-shielding, and enhancement of implant fixationin vivo. It is envisioned that an optimized combination of binder percentage and sintering temperature can result in the fabrication of scaffolds with the desired porosity and mechanical properties to fit the intended clinical application.
Effect of Strontium Enhanced Calcium Phosphate Coating on In Vitro Behavior of Human Mesenchymal Stem Cell (hMSC)
Authors: Uzoechi Samuel C. , Okoye Goddy C. , Ejeta Kennedy O. , Nkem Benjamin I. , Ndubuka Gideon I.
Published: August 2014

Calcium phosphate is a widely used material as coating for metallic implants. This research describes a biomimetic coating techniques based on deposition of calcium phosphate films on a Ti6Al4V plates that was used to study the effect of strontium additive on the behavior of hMSCs. In this study, strontium additive was homogenously deposited onto calcium phosphate films on a Ti6AlV plates by using a biomimetic techniques. Strontium affected composition and morphology of calcium phosphate deposited on a Ti6Al4V plates to a varying degree, according to concentration of solutions used. The effect of strontium additive on proliferation and differentiation of hMSCs depended on the solution and concentration tested. In general, all individual three coatings showed decreased hMSCs proliferation. Strontium additive demonstrated a significant increase in differentiation into osteogenic lineage when compared with the control and calcium phosphate films without strontium additive. However, no cytotoxic effect of strontium additive in the concentrations tested was detected. The Fourier transform infrared spectra showed that this new coating closely resembles bone mineral. The techniques illustrated in this study mimics bone mineral containing strontium additive, making it constructive for studying basic processes of in vitro bone formation. The results showed in this study can be used for changing bone graft substitutes by addition of strontium additive on implants in order to affect their performance in bone repair and regeneration. Also, the system can aid rapid bone formation around the implant, reducing therewith the patient’s recovery time after surgery.
In Situ Investigations for the Seismic Assessment of Existing Bridges
Authors: Pellegrino Carlo , Zanini Mariano Angelo , Zampieri Paolo , Modena Claudio
Published: August 2014

The outcomes of an in-situ experimental campaign in the context of the seismic assessment of 71 existing road bridges belonging to the Veneto regional roadway network have been described. An in-situ and laboratory experimental campaign on basic materials was carried out with the aim of characterizing the main mechanical material parameters of each bridge. Structural assessment has been subsequently carried out, comparing the obtained results with those deriving from a preliminary analysis conducted on the basis of some assumptions on materials’ mechanical characteristics related to the original design documents and the construction practice at the time of the structures’ edification.
Seismic Behaviour Analysis of Classes of Masonry Arch Bridges
Authors: Zampieri Paolo , Zanini Mariano Angelo , Zurlo Rocco
Published: August 2014

The paper describes a simplified methodology for the evaluation of the seismic retrofit intervention types to be performed on clusters of multi-span masonry arch bridges, on the basis of the main bridges’ geometrical characteristics. The structural behaviour of the analysed sample bridges has been evaluated in their main directions highlighting the potential local and global vulnerabilities and the related retrofit intervention typologies that need to be selected. The main aim of this study is to take the form of an useful tool for the identification of the best retrofit strategies for each masonry bridge structure in function of its geometrical characteristics and thus planning rationally the management of these bridges belonging to railway networks.
Dynamic Analysis of a Historical Fortified Tower
Authors: Diaferio Mariella
Published: August 2014

The present paper is centered on the static and dynamic analysis of the fortified tower of San Felice sul Panaro (Italy) citadel. The examined tower, that dated back to the XIV century, is particularly vulnerable to seismic forces, as the recent Emilia Romagna earthquake (2012) has demonstrated, and can be considered representative of a wide class of masonry towers located in the north of Italy.
In order to evaluate the structural behavior, detailed numerical models of the tower with different level of complexity have been defined. In particular, the present paper shows the preliminary results of the static and dynamic analysis performed on such models and the influence of some parameters on the tower dynamic behavior.
Modeling of Masonry Vaults as Equivalent Diaphragms
Authors: Marseglia Pier Silvio , Micelli Francesco , Leone Marianovella , Aiello Maria Antonietta
Published: August 2014

Recent seismic events that occurred in Italy revealed the vulnerability of masonry buildings with vaulted roof with respect to horizontal forces. Assuming that a large part of the architectural heritage is made by vaulted masonry buildings, measures aimed at improving the seismic response of such structures is a strategic objective. In the present work the behavior of masonry vaults is modeled through equivalent plane element (diaphragm), and a modeling procedure is proposed for design. Different types of vaulted structural roofs were studied, considering geometries with simple and double curvature. An extensive parametric analysis was conducted by varying significant structural parameters: vault thickness, in-plane dimensions, constraint conditions and presence or not of side walls. In the proposed model the complex geometry of the vault is replaced by an equivalent plate, with the intent of modeling the entire building as a frame being equivalent to the real structural with respect to the seismic response. The equivalent plate is defined as an element generally orthotropic with the same in-plane dimensions and same thickness of the vault from which it is derived.
Building Vulnerability: An Interdisciplinary Concept
Authors: Vlamos Panayiotis , Chrissikopoulos Vassilios , Psiha Maria
Published: August 2014

Vulnerability of historical city cores is an important issue for numerous countries in seismic areas such as Greece and Italy. In the literature there are a wide range of approaches to defining, modeling and measuring vulnerability. These different views originate from different concepts of the causes of a disaster. Research into vulnerability is often grounded in one of these views. In this paper we present the key factors for vulnerability modeling of historical buildings caused by dynamic loading.
A Dynamic Identification of a Historical Building Using Accelerometers with Interface Modules and a Digital Synchronization Method
Authors: Spedicato Luigi , Armeni Iro , Giannoccaro Nicola Ivan , Avlonitis Markos , Papavlasopoulos Sozon
Published: August 2014

This paper describes a study about the San Giacomo building for testing the dynamic identification applicability of a low-cost monitoring system, consisting of accelerometers and acquisition modules. The Stochastic Subspace Identification (SSI), a well-known technique of Operational Modal Analysis (OMA), is applied to the experimental data to evaluate the possibility of identifying the first frequencies of the building. Moreover, in order to solve the lack of synchronization of the monitoring system, an innovative method based on the phase delay of each signal is presented and used for digitally synchronizing the data.
Synchronization Issues in an Innovative Wireless Sensor Network Architecture Monitoring Ambient Vibrations in Historical Buildings
Authors: Koufoudakis George , Skiadopoulos Nikos , Magkos Emmanouel , Oikonomou Konstantinos
Published: August 2014

The problem of bridging the gap between the traditional wired monitoring systems and the wireless ones, was the objective of an innovative network architecture that elegantly combined benefits from both approaches. The monitoring focus is on historical buildings in which installing wires maybe range from difficult (e.g., fragile constructions) to impossible (e.g., prohibitive legislation). However, this innovative approach is vulnerable with respect to synchronization issues. In particular, all data sensed by different sensors need to have the correct universal time stamp. Since under this approach there is no central entity to take a synchronization role, in this paper the use of a local NTP server is proposed and as it is shown here using experimental results, this approach suffices for the particular monitoring needs. Thus, the claim that the innovative system can efficiently support the required monitoring of ambient vibrations in historical buildings.
Vulnerability Reduction Procedures in Ordinary Urban Management - The Urban Building Code of Faenza
Authors: Carocci Caterina F. , Copani Pietro , Marchetti Lucia , Tocci Cesare
Published: August 2014

The paper describes a study carried out for historical centre of Faenza (RA), developed by the Dept. of Architecture (UniCT) within an agreement with Faenza Municipality. The study aimed at elaborating guidelines for mitigation of buildings’ vulnerability in historical urban fabric to be used in ordinary government of the city as seismic prevention intervention.
Morphology of Roman, Islamic and Medieval Seismic Design: Pointed Arch and Ablaq
Authors: Camiz Alessandro
Published: August 2014

In ancient written sources earthquakes were mostly interpreted as a divine punishment for human sins, only few authors instead interpreted the seismic event as a phenomenon independent from human actions. Considering the built architectures as material documents, several examples can be found, suggesting that there was an empyrical knowledge of the consequences of earthquakes on buildings. Modern literature on the topic, mostly within engineering studies, lacking an historical approach, assumes that in ancient times science ignored the physical nature of seismic events and consequently declares that architects couldn’t consider dynamics in their projects. The close examination of some examples shows clearly that Roman, Islamic and Medieval architects had an empirical knowledge of dynamics, probably based on post-seismic reconstruction. This knowledge developed through history, so it is possible to outline a history of seismic design way before the Lisbon earthquake (1775), considered by many authors as the beginning of the history of seismic design.
Effect of Solid/Liquid Ratio during Curing Time Fly Ash Based Geopolymer on Mechanical Property
Authors: Rahmiati Tia , Azizli Khairun Azizi , Man Zakaria , Ismail Lukman , Nuruddin Mohd Fadhil
Published: August 2014

Geopolymer is produced from the alkali activation of materials rich in Si and Al such as fly ash. Based on the experimental and characterization result, solid to liquid ratio influenced the setting time and compressive strength of geopolymer in order to have good mechanical property. The optimum setting time and compressive strength were obtained at 3 : 1 solid to liquid ratio. Optimum curing time reach at 14 days.
The Influence of Alkali Activator Concentration to Mechanical Properties of Geopolymer Concrete with Trass as a Filler
Authors: Risdanareni Puput , Ekaputri Januarti Jaya , Triwulan
Published: August 2014

This paper describes one of the varying factors influencing the mechanical properties of geopolymer concrete. Fly ash and volcanic material called trass was used as raw materials, while sodium Hydroxide (NaOH) and Sodium silicate (Na2SiO3) was applied as an alkali activator. Mechanical properties were assessed by compressive test, the concentration of NaOH used in this study was eight and ten Molars, and ratio of Na2SiO3to NaOH by mass was 0.5, 1, 1.5, 2, and 2.5. Test results indicated that the strength of geopolymer concrete and binder were hardly influenced by concentration of NaOH in solution and the activator ratio. Binder with activator ratio of 2.5 has the highest compressive strength both in 8M and 10M NaOH system. However, in concrete, there are a few difference, concretes made with 8M NaOH and activators ratio of 2 have the highest compressive strength. This result might due to the low workability of fresh geopolymer concrete. On the other hand, binder and concrete made with 10M NaOH, showed the highest compressive strength when they were made with the activator ratio of 2,5.
Compressive Strength of Concrete with Recycled Glass as Partial Aggregate Replacement
Authors: Hamid Roszilah , Zubir M.A.
Published: August 2014

In this study, recycled glass is used to replace the natural fine aggregate in different mix proportions to obtain the optimum combination that will produce the highest strength. The control samples are Grade 30 ordinary Portland cement concrete (OPCC) containing 100% natural sand and coarse aggregate. The recycled glass concretes contain 70% natural fine aggregate + 30% size 300 micron crushed glass (Sample 2), and 70% fine aggregate + 15% size 300 micron crushed glass + 15% size greater than 300 micron crushed glass (Sample 3). The compressive strengths of the concrete samples with recycled glass are higher than the control samples at all ages of 7, 28, 56 and 90 days. At age 60 days, the strength gain of the control samples shows no significant increment but both samples that include recycled glass still show significant increment in strength. It is found that recycled glass performed better when utilised at size 300 microns and less. The recorded strength of the control, Sample 2 and 3 at 90 days are 47, 61 and 55 MPa.
The Experimental Determination of the Friction Stress between the Semi-Product and the Active Plate at the Multiaxial Forging of Copper
Authors: Cazac Alin Marian , Al Bakri Abdullah Mohd Mustafa , Predescu Cristian , Sandhu Andrei Victor , Bejinariu Costică
Published: August 2014

The paper aims the determination of the friction force by means of external friction stress, at the severe plastic deformation processing using cyclic closed-die forging method. It is known that the total force used at the severe plastic deformation by the method of multiaxial forging is being composed by the deformation force itself and the friction force between the semi-product and the deformation tools. Once the friction stresses known, for a certain material, one can determine the friction force corresponding for a given deformation of a semi-product of a particular shape and sizes. By means of the flowing curve of the semi-product material one can determine the deformation force, which together with the friction force give the total necessary force for a deformation and so one can choose the necessary equipment for the processing of the material by severe plastic deformation. For this purpose it has been severely plastic deformed by the method of multiaxial forging, a semi-product having the sizes 10x10x20 mm, the finished part having the same sizes and shape. It has been measured the deformation force and the extraction force of the finished part from the cavity of the active plate, the late being used for the determination of the friction stress between the semi-product and the active plate.
Leachability of Fired Clay Brick Incorporating with Sludge Waste from Mosaic Industry
Authors: Kadir A.A. , Jamil H.H. , Abdul Rahim A.S.
Published: August 2014

The amount of sludge wastes from industrial, mining, domestic agriculture activities are about 60200 tons per year. The increasing of the waste will have significant impact towards environment and energy conservation. Many attempts have been made to incorporate sludge waste into brick for example fly ash sludge, sewage sludge, water sludge and ceramic sludge and advantages on the properties have been found but heavy metals leachibility will be the main concerned. Therefore, sludge waste is a potential alternative to convert into useful products as a building material that can alleviate the disposal problems. Therefore, in this study, the characteristics of heavy metals were determined by using XRF. Four different mixing ratios of mosaic sludge waste at (0%, 1%, 5%, and 10%) were incorporated into fired clay brick. Each brick was fired in a heat controlled furnace at elevated temperatures of 1050°C. The characteristic of heavy metals from the sludge waste were determined by XRF and the result show that the sludge waste is high in iron (Fe) and Zicronium (Zr) followed by Barium (Br), Chromium (Cr), Cadmium (Cd), Copper (Cu) and Zinc (Zn). The leachability of heavy metals from the manufactured mosaic sludge brick were determined by using toxicity characteristic leachibility procedure (TCLP) and the results demonstrated that the culprit heavy metals were all complied to USEPA(1996) and EPAV(2005a).
Comparison between Thermal Interface Materials Made of Nano Carbon Tube (NCT) with Gad Pad 2500 in Term of Junction Temperature by Using CFD Software, FluentTM
Authors: Mohamed Mazlan , Al Bakri A.M. Mustafa , Wahab Razak , Zulhisyam A.K. , Mohd Sukhairi M.R. , Amini M.H.M. , Mohammad Amizi A.
Published: August 2014

This paper presents the comparison between thermal interface materials made of nano carbon tube (NCT) with Gad Pad 2500 in term of junction temperature by using CFD Software, FluentTM. 3D model of electronic packaging is built using GAMBIT and simulated using FLUENT software. The study was made for a microprocessors arranged in line under different types of inlet velocities and package (chip) powers. The results are presented in terms of average junction temperature when chip powers have been increased from 0.5 W to 2 W. The junction temperature is been observed and it was found that the junction temperature of the electronic packaging using nano carbon has lower junction temperature compare to the Gad Pad 2500. It also found that the NCT was able to reduce the junction temperature up to 20-30% compare to others thermal interface material.
Effects of Electro Osmotic Consolidation in South West of Johor: Small Laboratory Scale
Authors: Mohd Yusof Khairul Nizar , Ahmad Fauziah , Abdullah Mohd Mustafa Al Bakri , Mohd Tahir Muhammad Faheem
Published: August 2014

Clay soil is one of the problematic soils due to its natural states which have low bearing capacity and high compressibility. The effect and problem of the clay soil characteristic creates a problem for construction especially excessive settlement and this can lead to unstable and potential cracks of engineering structures. At presents, there are few of soil improvement types can be carried out to overcome these problems, and electro osmotic consolidation is one of the options. This method has been applied many years ago especially in european countries. The study encompasses the determination of water content, atterberg’s limits and undrained shear strength after electro osmotic consolidation treatment of clay soils taken from 0.5 m and 1.5 m at southwest part of johor. All the samples were tested according to BS1377:1990. An experimental study was implemented in a pvc cylinder tube having dimensions of 300 mm height and 100 mm diameter. In the results of electro osmotic consolidation tests by installing copper spring electrodes, the measured undrained shear strength was increased considerably at the anodes especially compared to the initial undrained shear strength due to electro osmosis process and consolidation. As laboratory studies of its measurement have shown, the application of electro osmotic consolidation after the application of a direct current applied voltage of 10 volts, at the anodes especially: (i) a decrease by approximately 35% in water content; (ii) an increase around 29% in undrained shear strength; and (iii) a decrease about 21% in index plasticity. The results obtained in this study shows that the electro osmotic enhanced 15 kpa vertical loading consolidation is a feasible approach in strengthening of south west soft clay in johor. It can be clearly suggested that the higher the voltage applied in the system, the higher readings of undrained shear strength and the lower of water content especially at the anodes.
Effect of Organic Modification on Dynamic Compression Properties of Polypropylene/Muscovite Layered Silicate Composites
Authors: Omar Mohd Firdaus , Jaya Haliza , Akil Hazizan Md , Ahmad Zainal Arifin , Rasyid Mohd Fadli Ahmad , Noriman N.Z.
Published: August 2014

In order to improve the mechanical properties of composite materials, one of the renowned techniques that can be applied is the filler modification. Still, no works were concern on this particular matter under dynamic standpoint. Therefore, in this study, both untreated and treated polypropylene/muscovite layered silicate composites were tested under static and dynamic loading up to 1100 s-1 using the universal testing machine (UTM) and the split Hopkinson pressure bar (SHPB) apparatus. Muscovite particles were treated with lithium nitrate and cetyltrimethylammonium bromide as a surfactant through surface modification. Results show that the treated polypropylene/muscovite samples with fine state of dispersion level shows superior mechanical performances as compared to untreated polypropylene/muscovite samples under an extensive range of strain rate investigated. Furthermore, the mechanical properties of both tested polypropylene/muscovite layered silicate composites also display great reliance on the strain rate applied where strength and stiffness properties were gradually increased with increasing strain rate. Key words: Organic modification; Strength and stiffness properties; Muscovite particles; Split Hopkinson pressure bar apparatus; Strain rates
The Flexural Properties of Reinforced Recycled Glass Concrete Beam
Authors: Hamid Roszilah , Zubir M.A.
Published: August 2014

In this study, recycled glass is used to replace the natural fine aggregate in different mix proportions. The control samples are Grade 30 ordinary Portland cement concrete (OPCC) containing 100% natural sand and coarse aggregate. The recycled glass concretes contain 70% natural fine aggregate + 30% size 300 micron crushed glass (Sample 2), and 70% fine aggregate + 15% size 300 micron crushed glass + 15% size greater than 300 micron crushed glass (Sample 3).The recorded strength of the control, Sample 2 and 3 at 90 days are 47, 61 and 55 MPa. Although the compressive strength for the concrete samples with recycled glass are higher than the control samples, the flexural test results show that, concrete with recycled glass has less ability to be fully functioning as a reinforced concrete by exhibiting their flexural strength at 91 % and 84% of the theoretical flexural strength whereas for the control specimen, its flexural strength is 10% higher than the theoretical value. Nonetheless, the toughness index of recycled glass concrete with 30% replacement of fine sand with recycled glass powder is at par with the control samples, which shows the ductile behavior of the recycled glass concrete.
Simulation of Nano Carbon Tube (NCT) in Thermal Interface Material for Electronic Packaging Application by Using CFD Software
Authors: Mohamed Mazlan , Al Bakri A.M. Mustafa , Wahab Razak , Zulhisyam A.K. , Iqbal A.M. , Amini M.H.M. , Mohammad Amizi A.
Published: August 2014

This paper presents the nanocarbon tube in thermal interface material for electronic packaging application by using three dimensional numerical analysis of heat and fluid flow in computer. 3D model of electronic packaging is built using GAMBIT and simulated using FLUENT software. The study was made for a microprocessors arranged in line under different types of inlet velocities and package (chip) powers. The results are presented in terms of average junction temperature when chip powers have been increased from 2 W to 5 W. The junction temperature is been observed and it was found that the junction temperature of the electronic packaging using nanocarbon was able to wind stand the increasing in chip power from 2 W until 5 W. It also found that the material selection play important roles to control and manage the junction temperature. The strength of CFD software in handling heat transfer problems is proved to be excellent.
Tensile Properties of Linear Low Density Polyethylene/Rambutan Peels (Nephelium chryseum Blum.) Flour Blends
Authors: Nadhirah A. Ainatun , Sam S.T. , Noriman N.Z. , Voon C.H. , Samera S.S.
Published: August 2014

Polyethylene (PE) has found well-known use as a packaging material. The effect of rambutan peels flour (RPF) content on the tensile properties of linear low density polyethylene filled with rambutan peel flour was studied. RPF was melt blended with linear low–density polyethylene (LLDPE). LLDPE/RPF blends were prepared by using internal mixer (brabender) at 160 °C with the flour content ranged from 0 to 15 wt%. The tensile properties were tested by using a universal testing machine (UTM) according to ASTM D638. The tensile strength of LLDPE/RPF decreased gradually with the addition of rambutan peels flour content from 0% to 15%. The Young’s modulus of LLDPE/RPF increased with increasing the RPF size and content.