bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of stochastic pressure loads on a medium head Francis runner
Authors: Morissette J F , Nicolle J 
Published: December 2019

Abstract
In recent years, major advances have been made in simulating dynamic and transient flows in hydraulic turbines. Overall, computational fluid dynamics (CFD) and finite element analysis (FEA) simulations have been quite successful and have helped to advance knowledge beyond the best efficiency point. The simulation of transient operations like startup and runaway has nearly become part of the standard toolbox. However, numerically predicting stochastic flows, such as those occurring during speed-no-load (SNL) regime, remains a challenge. Since these flows can have a significant impact on turbines’ life expectancy, CFD methods need to be improved. In this paper, we examine the SNL regime in a Francis turbine in which extensive dynamic fluctuations were measured. The approach used was to first focus on the CFD methodology required to better predict stochastic pressure loads with hybrid turbulence models such as the Scale-Adaptive Simulation–Shear-Stress Transport (SAS-SST) model and the relatively new Stress-Blended Eddy Simulation (SBES) model. This will then allow us to determine the amount of LES content required to accurately predict large-scale turbulent structures and the corresponding pressure fluctuations that they generate on blades.
Analysis of a propeller turbine operated in a full load operating point
Authors: Junginger Bernd , Riedelbauch Stefan 
Published: December 2019

Abstract
A full load operating point of a propeller turbine is investigated both numerically and experimentally. Steady state and unsteady flow simulations, using four different turbulence models with grid sizes up to 100 million elements, are validated with experimental results which are performed according to IEC 60193 standard. Due to the high swirl number of S = -0.175 at the runner outlet, steady state and unsteady RANS simulations are no longer capable to predict the correct flow field in the draft tube of the turbine. Hence, unsteady simulations with scale-resolving turbulence models, are performed. As a result of the high swirl a full load vortex rope is generated starting at the runner hub developing in the center of the draft tube. The integral quantities head and torque as well as the axial and tangential velocity components at five evaluation lines in the draft tube are validated with experimental results. Velocity components are both time- and phase-averaged, using the runner as trigger signal. Additionally, a comparison of local quantities, head loss in the draft tube and the pressure recovery factor is carried out. The turbulence quantities of the different approaches are evaluated at the evaluation lines applying the viscosity ratio or energy spectra at discrete points in the draft tube of the turbine.
Numerical investigation of solutions to suppress the inlet vortex of an existing booster pump
Authors: Decaix J. , Gaspoz A. , Fischer D. , Münch-Alligné C. 
Published: December 2019

Abstract
The study focuses on a booster pump used to feed the main pump of one unit of the FMHL hydropower plant (Veytaux I). From the beginning of the operation of the power plant, vibrations have been observed on this booster pump with sometimes the presence of cavitation erosion. The visualisations carried out show that a cavitating vortex develops at the suction side of the booster pump runner and causes the measured vibrations. The booster pump is running without any modification since the beginning of the operation of the power plant, however future mechanical failures cannot be excluded, since in these harsh conditions, the permissible mechanical strain shall be exceeded.
Flow numerical investigations have been carried out using OpenFOAM and shown the presence of vortices below the bell of the booster pump. The main vortex observed is assumed to be responsible for the vibrations due to its interaction with the runner blades and to promote the inception of cavitation, which could explain the cavitation erosion observed.
Several modifications of the chamber have been considered by simulation. Two of them provide a solution to suppress or at least to damp the vibrations due to the presence of vortices in the bell inlet.
Cost-effective CFD simulation to predict the performance of a hydrokinetic turbine farm
Authors: Pacot O , Pettinaroli D , Decaix J , Münch-Alligné C 
Published: December 2019

Abstract
After the performance assessment of a new hydrokinetic turbine prototype in the tailrace channel of a run-of-river power plant (Lavey, CH), the possibility to install a farm of such hydrokinetic turbines on this pilot site is investigated. In order to identify the optimal number and size of the machines as well as their location on this site, numerical simulations are carried out. Such a process requires to simulate a set of several free surface flow computations including different configurations of the farm in order to maximize the energy tapped by the machines. However, free surface flow computations are time and resources consuming. To allow such flow investigations, a different approach has been selected. In the present study, the turbines were replaced by a model mimicking the resistance effect of the machines. This model consists in a pressure drop applied at the turbine location to emulate the disturbance effect on the flow, especially the wake effect that will modify the available kinetic energy for the neighboring machines. Finally, it results that such a low CPU approach allows us to estimate the best location of the hydrokinetic turbines maximizing the energy harvested.
Temperature dependency of the growth rate of (Cu,Ni)6Sn5 on Cu-xNi substrates
Authors: Tan Xin Fu , Razak Nurul Razliana Abdul , Husain Muhammad Hafiz , McDonald Stuart , Nogita Kazuhiro 
Published: December 2019

Abstract
Cu6Sn5 is the most common intermetallic compound (IMC) in lead-free solder joints, and is also a promising anode material for advanced lithium-ion batteries. It has been reported that the growth rates of (Cu,Ni)6Sn5 in Sn-based solder alloy/Cu-xNi substrate couples are greatly accelerated compared to the intermetallic layers that form on a pure Cu substrate. Due to the faster growth rates, solidification can progress through a transient-liquid-phase reaction in commercially relevant timeframes. The complete reaction of the liquid Sn in the couple will result in a joint that is stable at high temperatures. Furthermore, the presence of Ni in the intermetallic suppresses the formation of a Cu3Sn layer and stabilises the (Cu,Ni)6Sn5 preventing a polymorphic transformation on cooling along with the associated induced strains. This study investigates the growth rates of (Cu,Ni)6Sn5 in Sn/Cu-xNi couples, where 0 <= x <= 14 wt%, and reports on the effect of temperature on the growth rates at temperatures above the melting point of Sn (231.9°C) between 232°C and 300°C. The results show the highest growth rates occur in the Sn/Cu-6Ni couples, and there is an increase of the (Cu,Ni)6Sn5 growth rate with increasing temperature due to faster diffusion and reaction rates.
Effect of different ratio of geopolymer paste based fly ash-metakaolin on compressive strength and water absorption
Authors: Azhar Nor Shida Dalila Mohd , Zainal Farah Farhana , Abdullah Mohd Mustafa Al Bakri 
Published: December 2019

Abstract
This paper presents the effect of different solid to solid (S/S) ratio by mixing the fly ash and metakaolin as geopolymer paste on the compressive strength and water absorption. Fly ash is a waste materials produced by combustion of coal at power plant while metakaolin was obtained by calcining the kaolin at 750 °C for 4 hours. Different weight percentage of S/S ratio of fly ash/metakaolin used were 50%:50% (Mix 1), 70%:30% (Mix 2) and 90%:10% (Mix 3). Alkaline activators that act as binder were sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions. The ratio of Na2SiO3/NaOH is 2.5 to 1. The mixture then placed into cylinder mould and left for 7, 14 and 28 days before it be tested. The product obtained were observed and it shows that Mix 2 has highest compressive strength for 28 days that was 41.22 MPa and has lower water absorption. The pore size decreases and permeability also decreases hence the strength potentially improve.
The influence of Copper and Bismuth element in Sn-Ag solders and ENIMAG substrate
Authors: Zolhafizi Jaidi , Azlina Osman. Saliza 
Published: December 2019

Abstract
The addition of copper and bismuth elements in Sn-Ag solders on interfacial reaction during reflow soldering and isothermal aging of SA25 and SACB25051 was investigated. The growth of intermetallic compound (IMC) was characterized by using scanning electron microscopy (SEM), optical microscope (OM) and energy dispersive x-ray (EDX). The results show the irregular circle shapes of (Cu,Ni)6Sn5 IMC at the interface of solder joint for SA25 while rod-like shape for SACB25051 during both reflow soldering process and isothermal aging. The SACB25051 solder showed the thinner IMC thickness compared to SA25 solder for both conditions. The Cu and Bi element in Sn-Ag solder promotes a slower growth rate of IMC formation during interaction. The thickness and morphology of the IMC for both solders increase gradually with increasing of aging time.
Decolorization of reactive red 2 dye by using pva- polyaniline immobilized system
Authors: Razak Mohd Fairul Sharin Abdul , Salleh Mohd Nazry , Azani Azliza , Zakir Nurul Izzati Muhammad 
Published: December 2019

AbstractThe immobilized of polyaniline (PANi) and polyvinyl alcohol (PVA) in bilayer system were studied base on several operational condition parameters such as loading and pH of the reactive red 2 dye solution. The PVA/PANi immobilized system was prepared by coating the PVA layer followed by deposition of PANi onto the surface of the glass plate. In this system, the addition of PVA particles works as binder between the PANi and the substrates. It was found that, PVA/PANi works as absorbent in this system and shown good response towards to the adsorption process of RR2 dye. This process can be seen by the decolorization ofthe dye. This decolorization was influenced by several factors which related to the interaction of dye with PVA/PANi composite and also during conditioning of dye as well. As a result, the adsorption process of RR2 dye in the immobilized system showed the best removal of dye under aerated system with the solution condition at pH 7. The percentage of dye removal was increased linearly with the amount of loading PVA/PANi. The rate of adsorption of dye was high at the beginning and after 30 minutes and onwards, all loading absorption rate has drop and the reading started to plateau indicates the surface areas of the system were nearly filled up by the dye particles. Thus, the highest adsorption was achieved was at 80 % removal after two hours. Indeed, by prolonging the time did not change the colour of the solution indicated to the maximum adsorption capacity of the process has been achieved.
Molecular dynamics simulation of the nano- reinforced lead-free solder at different reflow soldering process temperature
Authors: Sahrudin Intan Norshalina , Aziz Mohd Shahrizal Abdul , Abdullah Mohd Zulkifly , Salleh Mohd Arif Anuar Mohd 
Published: December 2019

Abstract
Temperature plays an important role in the reflow soldering process. Reflow soldering process which involving four basic stages including preheating, soaking, reflow and cooling require a specific range of temperature at each stage and the highest temperature is the reflow stage. In this study, the movement of the reinforced nanoparticles in the lead-free solder at three different stage temperatures which are 30°C,150°C and 250°C will be shown via Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) software. The simulation model able to show the movement of nanoparticles in the solder at three different reflow soldering process stages. The most vigorous movement of nanoparticles is shown at the temperature of 250°C while the least vigorous movement is shown at room temperature of solder which is at 30°C.
Characterization of geopolymer ceramic reinforced Sn-0.7Cu composite solder: Effect of milling time and speed.
Authors: Mostapha Marliza , Salleh Mohd Arif Anuar Mohd , Abdullah Mohd Mustafa Al Bakri , Thiaghu Maiteli , Zaimi Nur Syahirah Mohamad , Ahmad Romisuhani 
Published: December 2019

Abstract
The effect on the addition of optimally ball milled kaolin and fly ash geopolymer ceramic as reinforcement on the morphology and electrical properties of Sn-0.7Cu composite solder were explored. Geopolymer ceramics from fly ash class F and kaolin were prepared using geopolymer technology, milled at various speed and time. 1.0 wt. % of each sample were used to form composite solder via microwave sintered through powder metallurgy method. Structural characterization via SEM reveals that kaolin geopolymer ceramics has nano-sized subangular powder particles with larger amount of open porosity compared to fly ash geopolymer ceramics when milled at optimum speed and time. Four Point Probe test results showed a decreasing trend of electrical resistivity for kaolin geopolymer ceramics as the milling speeds and times increased. Overall, the results compared to electrical resistivity of other composite solder with various typical ceramic reinforcement additions, proves that kaolin geopolymer ceramics reinforcement to be the best option so far in term of morphology, electrical properties and its sustainable manufacturability.
Magnetic properties of TPU/NR blends: low loading NiZn and LNR added
Authors: Ahad Nor Azwin , Ahmad Sahrim Hj 
Published: December 2019

Abstract
Thermoplastic polyurethane and natural rubber blending are able to change the origin properties polymer material. Then, this blend was added with magnetic filler, NiZn at low loading of 1wt% to 5wt%. Other than that, liquid natural rubber (LNR) was also added as compatibilizer. The previous study presented, NiZn ferrite at 3wt% in TPU/NR blend is the optimum filler loading, but LNR was not unbeaten in its role as compatibilizer. The addition of this magnetic filler enhanced the magnetic properties on saturation magnetization and remanence magnetization but decreased the value of coercive force.
The appearance of machining burr as a cracking failure on twistlock pin
Authors: Mohd Wahid Mohamad Fitri , Rizam Shamsudin Saiful , Syazwan Sanusi Mohamad , Rajaselan Wardan , Azmi Rahmat 
Published: December 2019

Abstract
The failure analysis of the twist lock pin made of alloy steel is presented. The pin was visually observed to have a cracking character at curvature area after 45,000 cycles. Some non-destructive inspections were previously done. However it failed to detect any crack defect. The twist lock pin sample was further macro and microscopic analysis. The analysis found that the surface discontinuities that were previously presumed as a cracking morphology was actually a machining burr and improper machining marks. There were some micro- and nano-sized pinholes dispersed over the metal matrix of the twistlock pin sample. The microstructure of the twistlock pin was tempered martensite structure.
Removal of iron in rice husk via oxalic acid leaching process
Authors: Pa Faizul Che , Kein Wong Kok 
Published: December 2019

Abstract
Rice husk (RH), an agricultural waste which has been used as an alternative source for silica (SiO2). In order to produce high purity amorphous SiO2 from RH, acid leaching pre-treatment was required to remove the metallic impurities, followed by calcination at 800 °C to obtain the ashes. This research was studied about using oxalic acid as the leaching agent to remove iron (Fe) content in RH. The experimental parameters used in this study were acid concentration, reaction temperature, and leaching time. Based on the chemical composition analysis, the highest SiO2 content of 99.30% and the lowest Fe2O3 content of 0.43% were to be found in RHA which had treated under optimum parameters of 1.0 M of oxalic acid concentration, 90 °C of reaction temperature and 3 hours of leaching time. In addition, the particles of TRHA were observed with a tubular porous structure and irregular shape due to the leaching effect. Phase analysis by x-ray diffraction show that the amorphous SiO2 was confirmed as a broad diffused peak. It’s been found in the 2θ angle range of 18° to 30° with no crystalline peak observed.
Wettability and thermal properties of Sn-0.7Cu- 0.05Ni-xZn solder alloy
Authors: Ramli Mohd Izrul Izwan , Salleh Mohd Arif Anuar Mohd , Saleh Nurul Ashikin , Amli Siti Farahnabilah Muhd 
Published: December 2019

Abstract
This study investigate the effect of Zn additions on wettability and thermal properties of Sn-0.7Cu-0.05Ni lead-free solder alloy. The additional of alloying element have been developed by using casting technique with different percentage of Zn which is 0.5, 1.0 and 1.5 wt.%. The Sn-0.7Cu-0.05Ni-xZn solder alloy samples were then analyzed by using the optical microscope (OM) to observerse the wettability perfomance by contact angle. From this study, it was found that different composition of Zn affected the wettability and thermal properties of Sn- 0.7Cu-0.05Ni solder alloys. The addition of 0.5 wt.% has slightly increase the melting point while the addition of higher than 1.0 wt.% Zn can decrease the melting temperature. The addition of 0.5 wt.% of Zn also can reduce the undercooling of solder alloy. Thus, the minor addition of Zn for Sn-0.7Cu-0.05Ni can influence the wettability and thermal properties of solder alloy.
Effect of crumb rubber type on macroballoons towards physical and mechanical properties in syntactic foams
Authors: Zakaria Zunaida , Sathivelu Tiyagu 
Published: December 2019

Abstract
The effect of crumb rubber types on physical and compression properties of macroballoons in syntactic foams was investigated. Expanded polystyrene (EPS) beads were used as initiation material for starting up the macroballoons. The epoxy and hardener system were prepared to be coated with EPS beads and these coated EPS beads were later cured and post-cured to shrink the EPS beads thus producing epoxy macroballoons (EM). The prepared epoxy macroballoons then were coated with different crumb rubber type which is rejected NBR glove crumb (CG-EM) and waste tire rubber crumb (CT-EM). The EM, CG-EM, and CT-EM were then filled in the epoxy mixture to produce syntactic foam. The fabricated syntactic foam was characterized through physical and compression properties, respectively. Results indicated that the syntactic foam embedded with CT-EM shows high density, reduced radius ratio, and high compressive properties. The syntactic foam embedded with CT-EM shows the highest compressive strength and compressive modulus as compared to syntactic foam embedded with CG- EM and EM. The inclusion of the crumb rubber as the coating layer results in high energy absorption and stress transfer in syntactic foam.
Influence of NiO to SDC ratio on the properties of Ni-SDC cermet prepared via reduction process
Authors: Abdullah Salmie Suhana Che , Ismail Siti Sarah 
Published: December 2019

Abstract
This works presents the preparation of Ni-Ce0.8Sm0.2O1.9 (Ni-SDC) ceramic-metal from reduction of NiO-Ce0.8Sm0.2O1.9 (NiO-SDC) ceramics for application of solid oxide fuel cell. NiO-SDC powder with different weight percentage of NiO and SDC (100% NiO + 0% SDC), (80% NiO + 20% SDC), (70% NiO + 30% SDC) and (60% NiO + 40% SDC) was pelletized and sintered at 1400 °C for 4 hours. Then, pellet samples were undergone reduction process using mixed gas of hydrogen and nitrogen gas with concentration of 40% H2 and 60% N2 at 800 °C for 2 h. Phase analysis was done using X-ray Diffraction and it was found that for all samples, NiO was completely reduced to Ni, meanwhile SDC was remained in its phase. The density of the samples decreased after reduction, results in more porous samples were obtained. It was found that increasing NiO content lead to sample with higher porosity. The surface morphology of the samples was observed by using the Scanning Electron Microscopy.
Influence of kaolin geopolymer ceramic additions to the wettability and electrical properties of Sn-3.0Ag-0.5Cu (SAC305) lead free solder
Authors: Zaimi Nur Syahirah Mohamad , Salleh Mohd Arif Anuar Mohd , Abdullah Mohd Mustafa Al Bakri , Mostapha Marliza , Ahmad Romisuhani 
Published: December 2019

Abstract
The effect of kaolin geopolymer ceramic addition to the wettability and electrical resistivity of Sn-3.0Ag-0.5Cu (SAC305) lead free solder was successfully explored. Powder metallurgy with microwave sintering method was used to fabricate SAC305 composite solder. Five different weight percentage (wt.%) of kaolin geopolymer ceramic (0, 0.5, 1.0, 1.5 and 2.0 wt.%) were used in this study. The wettability of composite solder revealed the optimum contact angle was achieved at 1.0 wt.% with 20.8 °. Then, the electrical resistivity of composite solder showed significant change in the resistivity value.
Enhanced thermal and microstructure properties of Sn-1.0Ag-0.7Cu based lead-free solder with Titanium Oxide addition
Authors: Said Rita Mohd , Saud Norainiza , Nasir Norhayanti Mohd , Salleh Mohd Arif Anuar Mohd , Derman Mohd Nazree , Ramli Mohd Izrul Izwan 
Published: December 2019

Abstract
This paper presented the effects on thermal and microstructure properties of Sn–1.0Ag–0.7Cu (SAC107) lead-free solder alloy with the addition of titanium oxide (TiO2) particles. The SAC107 solders were reinforced with 0.25, 0.5, 0.75 and 1.0 weight percentage (wt.%) of titanium oxide (TiO2) particles to produce SAC107+TiO2 solder alloy composite. The solder alloy was prepared by microwave–assisted powder metallurgy route. Based on the results, it showed that the addition of TiO2 particles influenced the properties of the solder alloy composite by refining the intermetallic compound (IMC) at the bulk microstructure area and slightly decreasing the melting temperature.
Transient liquid phase bonding for solder-a short review
Authors: Saud Norainiza , Said Rita Mohd 
Published: December 2019

Abstract
The issues on the replacement of high Pb solder for high power module application has been a major concern among researchers since Pb could caused toxicity to the environment. Alternatively, transient liquid phase (TLP) has becomes a potential bonding technology for high power module devices. Typical TLP bonding for solder is a bonding method that using an interlayer of low and high temperature metal. However, a new transient liquid phase bonding which dealing with solder in the form of powder and paste has been developed. Both bonding methods have successfully increased the melting temperature of the bonded alloys higher than the bonding temperature as will be discussed further.
Flexural Properties of Al/Floral Foam Sandwich Composite Prepared by Hand Lay Up Process
Authors: Firuz Zainuddin , Shing Leong Chit , Fadzli Syed Adam Syed Nuzul 
Published: December 2019

Abstract
The flexural properties of aluminum sheet as the facings and floral foam as the core in layered sandwich composite were studied under three-point bending test. Adhesion of core onto aluminum sheets was done by manually spreading mixture of epoxy resin and hardener via hand lay-up procedure. There were four system studied, which are single foam-core sandwich system until four foam-core sandwich system. It was found that single foam-core sandwich has the highest flexural strength over the range of Al/floral foam-core sandwich system. The single foam-core sandwich has a well stress or total load distribution as compared to other three types of sandwiches. The smaller thickness to width ratio of single foam-core system is believed to enable the homogenous stress distribution of loading during testing. In addition, several modes of failure found such as delamination, crack and core failure. As the number of layers of sandwich increase, there were more modes of failure occur, which mostly due to the core failure of floral foam.