The effects of Mg addition on the microstructure and mechanical properties of thixoformed Al–5%Si–Cu alloys

AbstractIn this study, the effects of different amounts of magnesium (Mg) on the microstructures and tensile properties of thixoformed Al–5%Si–Cu alloys were investigated. Three different alloys containing various amounts of Mg (0.5, 0.8 and 1.2wt%) were prepared through the cooling slope casting technique, before they were thixoformed using a compression press. Several of the thixoformed samples were then treated with a T6 heat treatment, that is, solution treatment at 525°C for 8h, quenching in warm water at 60°C, followed by aging at 155°C for 4h. All of the samples were then characterised by optical microscopy (OM), scanning electron microscopy (SEM) energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis as well as by tensile tests. The results revealed that magnesium was able to refine the size of α-Al globules and the eutectic silicon in the samples. It was also observed that a compact π-Al9FeMg3Si5 phase was formed when the magnesium content was 0.8wt% and 1.2wt%. The mechanical properties of the thixoformed alloys improved significantly after the T6 heat treatment. The highest attainment was recorded by the latter alloy (i.e. with 1.2wt%Mg) with its ultimate tensile strength (UTS) as high as 306MPa, yield strength (YS), 264MPa, and elongation to fracture of 1.8%. The fracture of thixoformed alloy with a low Mg content (0.5wt%) showed a combination of dimple and cleavage fracture, whereas in the alloy that contained the highest Mg content (1.2wt%), cleavage fracture was observed

Mechanical Properties of Activated Carbon (AC) Coir Fibers Reinforced with Epoxy Resin

This research is to develop a carbon composite prepared from carbon coir fibers that is reinforced with epoxy resin. Carbon coir fibers were taken from three types of coir fiber specifically designated as CKCF, CYCF and CRCF. The samples were prepared using epoxy resin reinforced with carbon at different weight percentages for three types of coir fiber starting with 0wt.%, 2wt.%, 4wt.%, 6wt.%, 8wt.% and 10wt.%. The mechanical properties such as tensile stress and impact strength were used to characterize all the samples. The morphological study of reinforced samples was also conducted in this research using a SEM machine. The characteristics of all the composite materials were also investigated and discussed. It was determined that the CKCF sample exhibited better mechanical properties than the other coir fiber composites, having a higher average tensile stress value at 11.80MPa and higher impact strength values ranging from 268J to 276J at different carbon content. CKCF with 10wt% AC content had a tremendous impact strength compared with CYCF and CRCF

DISTRIBUTION AND DIVERSITY OF FUSARIUM SPECIES ASSOCIATED WITH GRASSES IN TEN STATES THROUGHOUT PENINSULAR MALAYSIA

Fusarium  is one of   the  important genera associated with grasses as saprophytes, endophytes and  pathogens. A  study was  carried  out  on  distribution  and  diversity  of  Fusarium  species associated  with  two  groups  of   grasses  in  10  states  throughout  Peninsular  Malaysia  i.e. agricultural  grasses  (Oryza  sativa  and  Saccharum  officinarum)  and  non-agricultural  grasses (Axonopus compressus, Centhotheca lappacea, Chloris barbata, Crysopogon aciculatus, Cyanadon dactylon, Dactyloctenium  aegyptium, Digitaria  ciliaris,  Echinochloa  colona,  Eleusine  indica,  Eragrostis  amabilis, Eragrostis malayana, Eragrostis uniloides, Ischaemum magnum, Panicum brevifolium, Panicum millaneum, Panicum repens, Paspalum  commersonii, Paspalum  conjugatum, Paspalum orbiculare, Pennisetum purpureum, Sacciolepis  indica, Sporobolus diander and Sporobolus  indicus). A  total of  474  isolates were single-spored and  identified by morphological characteristics. F.  semitectum was  frequently  isolated (23.6%), followed by F. sacchari and F. fujikuroi with 15.4% and 14.6%, respectively. The other nine species were F. solani (10.3%), F. proliferatum (8.9%), F. oxysporum (7.4%), F. subglutinans (6.5%), F.  equiseti  (5.5%), F.  verticillioides  (3.4%), F.  compactum  (2.5%), F.  chlamydosporum  (1.1%) and F. longipes (0.8%). Based on the Shannon-Weiner Index, F. solani was the highest (H' = 2.62) isolated from grasses. Species of  Fusarium from O. sativa were widely diverse with 11 species, followed by non-agricultural grasses with nine species and S. officinarum with only six species. This  is  the  first  report on diversity of  Fusarium associated with grasses  in Malaysia.Key words: Oryza  sativa,  Saccharum  officinarum,  non-agricultural  grass,  Fusarium  species, diversity  and Graminea

Distribution and Diversity of Fusarium Species Associated with Grasses in Ten States Throughout Peninsular Malaysia

Fusarium is one of the important genera associated with grasses as saprophytes, endophytes and pathogens. A study was carried out on distribution and diversity of Fusarium species associated with two groups of grasses in 10 states throughout Peninsular Malaysia i.e. agricultural grasses (Oryza sativa and Saccharum officinarum) and non-agricultural grasses (Axonopus compressus, Centhotheca lappacea, Chloris barbata, Crysopogon aciculatus, Cyanadon dactylon, Dactyloctenium aegyptium, Digitaria ciliaris, Echinochloa colona, Eleusine indica, Eragrostis amabilis, Eragrostis malayana, Eragrostis uniloides, Ischaemum magnum, Panicum brevifolium, Panicum millaneum, Panicum repens, Paspalum commersonii, Paspalum conjugatum, Paspalum orbiculare, Pennisetum purpureum, Sacciolepis indica, Sporobolus diander and Sporobolus indicus). A total of 474 isolates were single-spored and identified by morphological characteristics. F. semitectum was frequently isolated (23.6%), followed by F. sacchari and F. fujikuroi with 15.4% and 14.6%, respectively. The other nine species were F. solani (10.3%), F. proliferatum (8.9%), F. oxysporum (7.4%), F. subglutinans (6.5%), F. equiseti (5.5%), F. verticillioides (3.4%), F. compactum (2.5%), F. chlamydosporum (1.1%) and F. longipes (0.8%). Based on the Shannon-Weiner Index, F. solani was the highest (H' = 2.62) isolated from grasses. Species of Fusarium from O. sativa were widely diverse with 11 species, followed by non-agricultural grasses with nine species and S. officinarum with only six species. This is the first report on diversity of Fusarium associated with grasses in Malaysia

Probiotic administration of Litopenaeus vannamei: Is there any negative effect on the fatty acid profile of meat?

It has been found that appropriate probiotic applications increased growth performance and disease resistance in shrimp. Bacillus subtilis has been suggested as a potent probiotic in improving growth performance and enhancing immune response in white shrimp, Litopenaeus vannamei. The aim of this work was to evaluate the possible effect of B. subtilis administration on the meat fatty acid profile of white shrimp, L. vannamei. Two groups of shrimps received B. subtilis strains L10 and G1 from the B. subtilis-supplemented feed (10^5 and 10^8 CFU g^-1) while two other groups received it from the rearing water (10^5 and 10^8 CFU ml^-1). One group received no B. subtilis and served as control. According to the results, there was no significant difference between the muscle fatty acid profiles of shrimps administrated by probiotic and control group. This study showed that B. subtilis administration, in either diets or water, did not have any negative effect on fatty acid profiles of L. vannamei meat

Named Entity Recognition using Fuzzy C-Means Clustering Method for Malay Textual Data Analysis

The Named Entity Recognition (NER) task is among the important tasks in analysing unstructured textual data as a solution to gain important and valuable information from the text document. This task is very useful in Natural Language Processing (NLP) to analyse various languages with distinctive styles of writing, characteristics and word structures. The social media act as the primary source where most information and unstructured textual data are obtained through these sources. In this paper, unstructured textual data were analysed through NER task focusing on the Malay language. The analysis was implemented to investigate the impact of text features transformation set used for recognising entities from unstructured Malay textual data using fuzzy c-means method. It focuses on using Bernama Malay news as a dataset through several steps for the experiment namely pre-processing, text features transformation, experimental and evaluation steps. As a conclusion, the overall percentage accuracy gave markedly good results based on clustering matching with 98.57%. This accuracy was derived from the precision and recall evaluation of both classes. The precision result for NON_ENTITY class is 98.39% with 100.00% recall, whereas for an ENTITY class, the precision and recall are 100.00% and 88.97%, respectively

Effect of semi-solid forming temperature and heat treatment on mechanical properties and microstructure of Mg-Al-Zn Alloy (AZ91D) for automotive light application

Magnesium alloy usage in manufacturing engineering components resulting in weight reduction and as a consequence, reduction in fuel and energy consumption. Magnesium has a relatively low density and roughly 30% lighter than aluminum. However, magnesium is considered to be difficult to deform because of theHCP structure. In this present work, the effect of semi-solid forming temperature and heat treatment on mechanical properties of Mg-Al-Zn were investigated. Mg-Al-Zn ingot was machined into a billet and formed with three different temperatures and underwent T4 heat-treatment process. To determine the mechanical properties and microstructure of the magnesium alloy, tensile and hardness test were performed and the result indicates that the highest average maximum tensile stress was achieved at 209 MPa at 530ºC after forming with T4 heat treatment and highest hardness value was at 21.44 HRB at 560ºC. On the other hand, effect of the forming temperature gives impact to the evolution of the microstructure from large grain size (as-cast) to the smaller grains size (0.00797mm2) forming at 560°C. This relate to the extensive dynamic recrystallization (DRX) occurs during forming and Mg-Al-Zn was sensitive with heat either direct or indirect heating method

EXPERIMENTAL INVESTIGATION OF DRILLING PROCESS USING NANOFLUID AS COOLANT

Nanofluid coolant is one of the new formulation of cutting fluids used in machining in order to obtain better surface finish of products. In this study, the effect of various coolants (nanofluid and pure deionized water) and cutting parameters (cutting speed and feed rate) to the machining performances of titanium alloy was investigated by using drilling process. A series of experiments were conducted using Design of Experiment (DOE) and the machining performances were measured in terms of surface roughness and cutting temperature. The results show that better surface finish and lower cutting temperature can be obtained by using carbon nanofiber nanofluid compared to that of pure deionized water. The significant factors that influence the surface roughness of titanium alloy are feed rate and coolant. Coolant also plays an important role to reduce the cutting temperature during the drilling process

Performance evaluation of m3 bottleneck based heuristic for M1M2M3 flow shop

This project investigates the possibility of developing scheduling heuristic using bottleneck approach for a three machine flow shop scheduling with the tendency of dominant machine at the first process. Due to the re-entrant and permutation nature of the process routing, the actual bottlenecks were identified as M3 and it utilized makespan algorithms to identify bottleneck categories. Using these conditions, a new bottleneck based heuristic which called BB is developed and tested using Macro Programming in Microsoft Excel. The main objective of this project is to evaluate the performance of M3 bottleneck-based heuristic for M1M2M3 flow shop problems. A total of 3000 simulations were conducted using randomly data in order to evaluate the accuracy of the heuristic. The heuristic performance was evaluated for six and ten job problems. The dominance level groups are divided into levels of weak, medium and strong dominance. For each job problem, the BB results were compared against the results of complete enumeration and lower bound analysis. The results suggested that BB heuristic is very effective in solving scheduling problems within the strong P3 dominance level range

MATHEMATICAL MODELLING OF THE PASSIVE AND SEMI-ACTIVE AUTOMOBILE SUSPENSION SYSTEMS IN FORD SCORPIO CAR MODEL

The suspension is a system of spring or shock absorbers connecting the wheels and axles at the chassis of a vehicle. In this study, Ford Scorpio car with passive and semi-active suspension system are formulated using Second Order Differential Equations (ODE). These models were solved analytically using the undetermined coefficient and Cramer rule methods. The comparison between passive and semi-active suspension system also conducted to measure such as displacement, frequency and time by plotting graphs. The passive system resulted that a constant displacement roughly at 0.035 m while 0.025 m was obtained by a semi-active suspension system. Semi-active system took t = 1 s to yield a constant displacement while for the passive suspension system required t = 1.5 s. The comparison showed the semi-active results were better than a passive suspension system