Hasil Pencarian  ::  Simpan CSV :: Kembali

"Ballast is one of themain structures for the railway tracks. It can resist the lateral movementunder dynamic loading transferred by the passing trains with repeatedly. Undersome circumstances, ballast can suffer degradation or breakdown due to therepeated loading and maintenance. Ballast is easily exposed to the weatherbecause it is laid on the track. Acid rain affects the performance of therailway track near the industrial and urbanarea. As a result, it starts to foul and the small chips from ballast filledthe void, as well as reduce the shear strength of ballast particles. Thissituation can contribute into the increasing of maintenance frequency andcosting. This paper examines the potential of rubber inclusions in increasingthe shear resistance of rubber-ballast composites in simulated water and acid soakedconditions with several configuration. This lab-based exploratory work is only static load simulation in conventional shear boxsetup measuring 60 mm × 60 mm.The aggregates size is 10 times smaller than actual size of ballast. In orderto identify the shear resistance deterioration of rubber-aggregates mixtureunder poor drainage conditions by soaked a batch of aggregates in water andacid solution for 2 weeks to simulate accelerated weathering effects. The shearresistance did not rise dramatically with the rubber reinforcement. Thissusceptible shear strain plots indicate ductile behaviour on theaggregates-rubber composites. This is evident by the linear rise of shearstress with strain up to approximately 10% for the control samples (CS) untilit reaches a constant value. Note that all the specimens including CS are in aloose state during the testing because there were no tamping been applied onthe samples. Overall the circular patch (CP) specimen was the most favourablethan the other configurations. Both mechanisms contributed to the reducedoverall subsistence, accompanied by an increase in the shear resistance. Theinclusion of rubber elements apparently prevented the dilation of the granularmaterial when approaching the shear failure and the reducing the settlement."

"Ballast is one of the main structures for the railway tracks. It can resist the lateral movement under dynamic loading transferred by the passing trains with repeatedly. Under some circumstances, ballast can suffer degradation or breakdown due to the repeated loading and maintenance. Ballast is easily exposed to the weather because it is laid on the track. Acid rain affects the performance of the railway track near the industrial and urban area. As a result, it starts to foul and the small chips from ballast filled the void, as well as reduce the shear strength of ballast particles. This situation can contribute into the increasing of maintenance frequency and costing. This paper examines the potential of rubber inclusions in increasing the shear resistance of rubber-ballast composites in simulated water and acid soaked conditions with several configuration. This lab-based exploratory work is only static load simulation in conventional shear box setup measuring 60 mm × 60 mm. The aggregates size is 10 times smaller than actual size of ballast. In order to identify the shear resistance deterioration of rubber-aggregates mixture under poor drainage conditions by soaked a batch of aggregates in water and acid solution for 2 weeks to simulate accelerated weathering effects. The shear resistance did not rise dramatically with the rubber reinforcement. This susceptible shear strain plots indicate ductile behaviour on the aggregates-rubber composites. This is evident by the linear rise of shear stress with strain up to approximately 10% for the control samples (CS) until it reaches a constant value. Note that all the specimens including CS are in a loose state during the testing because there were no tamping been applied on the samples. Overall the circular patch (CP) specimen was the most favourable than the other configurations. Both mechanisms contributed to the reduced overall subsistence, accompanied by an increase in the shear resistance. The inclusion of rubber elements apparently prevented the dilation of the granular material when approaching the shear failure and the reducing the settlement."

"The present work aims to improve the microstructure and hardness relatedproperties of age hardened Al6061-SiC reinforced composites produced by a two stage stir casting method. Three composites with2, 4, and 6wt. % (35-40μm) of SiC reinforcement are subjected tomicrostructural examination and hardness test at different locations to analysethe uniform distribution of the reinforcements in the matrix. As-castcomposites are solution-treated at 558°C, followed by an aging treatment conducted at 100, 150, and 200°C, during which peak hardness values are noted. The peak agedsamples are subjected to hardness and wear tests. In line with the objectives, ranges from 80-100% and 120-145% additional increase in hardnessvalues are observed over as-cast alloy during the aging treatment conducted at 100, 150 and 200°C, respectively. Lower temperature aging showssubstantial improvement in hardness and wear resistance over high temperatureaging in each respective group. Alsohigher weight percentages of reinforced composites show excellent wearresistance, due to the presence of eroded iron particles fromthe counter surface which is regarded as a beneficial effect during the wear test. The presence of SiC particles provides more sites for the nucleation of fineprecipitates. These fine precipitates hinder the movement of dislocation andthus increases hardness as well as wear resistance after the precipitation hardening treatment."

"This paper reports onthe investigation of thermal properties of Kapok, Coconut fibre and Sugarcanebagasse composite materials using molasses as a binder. The composite materials were moulded into12 cylindrical samples using Kapok, Bagasse, Coconut fibre, Kapok and Bagassein the ratios of (70:30; 50:50 and 30:70), Kapok and Coconut fibre in theratios of (70:30; 50:50 and 30:70), as well as a combination of Kapok, Bagasseand Coconut fibre in ratios of (50:10:40; 50:40:10 and 50:30:20). The sample size is a 60 mmdiameter with 10?22 mm thickness compressed at a constant load of 180 N using a Budenbergcompression machine. Thermal conductivity and diffusivity tests were carriedout using thermocouples and theresults were read out on a Digital Multimeter MY64 (Model:MBEB094816), whilea Digital fluke K/J thermocouple meter PRD-011 (S/NO 6835050) was used to obtain thetemperature measurement for diffusivity. It was observed that of all the twelvesamples moulded, Bagasse, Kapok plus Bagasse (50:50), Kapok plus Coconut fibre(50:50) and Kapok plus Bagasse plus Coconut fibre (50:40:10) has the lowestthermal conductivity of 0.0074, 0.0106, 0.0132, and 0.0127 W/(m-K) respectivelyand the highestthermal resistivity. In this regard, Bagasse has the lowest thermalconductivity followed by Kapok plus Bagasse (50:50), Kapok plus Bagasse plusCoconut fibre (50:40:10) and Kapok plus Coconut fibre (50:50)."

"Cold formedsteel has relatively high width-to-thickness ratio elements, which causes it tobuckle easily. Combining it with timber laminas would be an effective solutionfor reducing this buckling problem. This research focuses on the connectionsystem of a cold formed steel-timber composite, which was obtainedby attaching several timber laminas to the web part of cold formedsteel using screws. The connection used two bolts that were 8 mm in diameter,as well as two different kinds of side plates: steel and plywood. Cold formedsteel 75Z08 and Swietenia mahagoni(moisture content 12.2%; specific gravity 0.77) were used for connections andwere loaded in parallel and perpendicular directions. In addition, theconnections of cold formed steel (without timber laminas) usingself-drilling screw fasteners were tested until failure. Numerical analysispredicting the load-slip curve and apparent yield load of the composite joints wascarried out using the DOWEL program and the European Yield Theory,respectively. The test results showed that the connection system with steelside plates is capable of accommodating the strength increase of compositemember, as it has a maximum load carrying capacity and initial slip modulus ofabout 4.5 and 2 times larger than those of the cold formed steel connections, respectively. In the caseof a connection system with plywood side plates, its joint properties aresimilar to those of the cold formed steel connection, except that it has largerjoint deformation."

"Batteries on the markettoday still use liquid-type electrolytes, which can result in safety issuescaused by electrolyte leakage. Therefore, studies that search for solid-stateelectrolytes are important for resolving these issues. In this research, acomposite of lithium phosphate-montmorillonite-polyvinylidene fluoride (Li3PO4-MMT-PVDF)has been characterized with the aim of detecting the electrochemicalperformance of Li3PO4 with the addition of MMT. Li3PO4samples were prepared through a solid-state reaction, which was then mixed with MMT, which hada composition ranging from 5 wt% to 20 wt%, and 1 wt% PVDF as a binder. Thischaracterization was conducted with structural, morphological, andelectrochemical aspects. The structural test showed that the X-ray diffraction (XRD) pattern was dominated by Li3PO4 peaks and MMT aluminosilicates. The electrochemical characterization indicatedthat the conductivity value of the composites was greater than that of Li3PO4.The highest conductivity was achieved with a 15 wt% MMT addition, with adielectric-constant value of 74.9 at a frequency of 10 kHz."

"Catamaran resistance is very complex compared to monohull resistance, so it is particularly worthy of research. The below-water-level hull form influences the fluid flow characteristics around the ship, which either increases or decreases the total resistance. This study focuses on developing a new hull form by using the Lackenby Method to modify an existing hull form in such a way that reduces the total resistance. The total resistance was calculated using computational fluid dynamics, since the Navier-Stokes equation is built into the Tdyn software.

The research results show that hull form changes can in fact decrease or increase the ship?s total resistance. The best new hull form was chosen for its value of least total resistance."

"The objective of this research was to study the effects of highly moist inlet air conditions such as temperature, relativehumidity, and frontal air velocity on the value of the Lewis number (Le) in the cooling and dehumidifying process of air. A finned tube cooling coil was testedunder ranges of temperature, relative humidity and frontal velocity. It wasfound that the Lewis number (Le) varied within the range of 0.92-1.62 and that the increase in inlet air relative humidity tends todecrease the Lewis number (Le). Based on theexperimental, a correlation for predicting the Lewis number (Le) was also established in this article. Thecorrelation has the mean absolute error (MAE) of 3.04% and covers 98.07% of the data where a discrepancy within ± 10%."

"As a result ofwaterflooding, inorganic salt precipitation occurs in the different parts of anoil production system, thereby leading to damage of production equipment.Different parameters affect the kinetics of salt precipitation. Scaleinhibitors are widely used to prevent inorganic salt formation. In this study,the effect of reservoir pressure, temperature, and mixing ratio of injection toformation water on calcium sulfate and barium sulfate precipitation wasinvestigated. For this purpose, two different formation waters and oneinjection water were used. In addition, the effect of temperature and mixingratio on inhibition performance was studied. Four different existing industrialscale inhibitors and one new scale inhibitor were used. The performance of thescale inhibitors was determined under static and dynamic conditions. Results ofthe study showed that calcium sulfate precipitation increased with an increasein temperature and a decrease in pressure. Barium sulfate precipitation wasfound to increase with a decrease in the temperature. The effect of pressure onbarium sulfate formation was negligible. The developed scale inhibitor showedthe highest performance for the prevention of calcium sulfate and bariumsulfate formation. A change in temperature from 60°C to 120°C reduced theinhibitor performance by 3%. In the cases of calcium sulfate and bariumsulfate, the minimum performance of the scale inhibitor was observed when themixing ratios of injection to formation waters were 60:40 and 50:50,respectively."