Kaedah unsur terhingga (FEM) berdasarkan pemodelan dan simulasi proses pemotongan telah menarik minat ramai penyelidik secara berterusan untuk mengkaji lebih mendalam terutamanya mengenai penjanaan daya dan suhu di dalam zon pemotongan yang sebelum ini tegasan tidak boleh diukur secara langsung. Dalam kajian ini, simulasi proses pemotongan ortogon besi tuang mulur (FCD 500) menggunakan mata pemotong karbida pada pelbagai keadaan angin sejuk telah dikaji. Perisian DEFORM digunakan untuk menjalankan simulasi proses pemotongan ortogon dengan laju pemotongan (100-300 m/min), kadar suapan (0.15-0.35 mm/pus), kedalaman pemotongan (0.2-0.8 mm) dan suhu angin sejuk (2o -25oC). Mata pemotong mempunyai jejari hidung mata pemotong 0.4 mm, sudut sadak, α =5o dan sudut kelegaan, β = 7o. Reka bentuk uji kaji adalah menggunakan kaedah Taguchi dalam tatasusunan ortogon L9, nisbah S/N dan analisis Pareto ANOVA digunakan untuk menganalisis kesan parameter pemotongan terhadap hasil pemesinan iaitu daya, tegasan dan suhu semasa pemesinan. Keputusan menunjukkan kadar suapan memberikan pengaruh yang paling tinggi (96.12%) terhadap daya pemotongan. Tegasan pemotongan paling dipengaruhi oleh kadar suapan iaitu 78.87%. Kajian ini telah membuktikan, banyak masa, kos dan tenaga dapat dijimatkan dalam mengkaji kebolehmesinan sesuatu bahan secara simulasi berbanding dengan kaedah eksperimen, di samping keputusan yang tepat diperoleh.
Tool life of the cutting tools is considered as one of the factors which has effects on machining costs and the quality of machined parts. The topic of tool life prediction has been an interesting and important research topic attracting the attention of a wide number of researchers in this particular area. In terms of the suitable methods used in this research topic, it is stated that both statistical and artificial intelligence (AI) approaches can be employed to model tool life. For further justifying the capability of the ANN model in predicting tool life, the current study was based on conducting experimental work for collecting the experimental data. After carrying out the experiment, 17 data sets were collected and they were divided into two subsets; the first one for training and the second for testing. Since the data sets seemed to be lower than the number of data sets used in previous studies, we attempted to make verification of the ability of the ANN model in learning and adapting with low training and testing data. Diverse topologies accompanied with single and two hidden layers were created for modeling the tool life. For choosing the best and most effective network, the study adopted the mean square error function as criteria for the evaluation of the network selection. Thus, based on the data generated from the same experiment, a regression model (RM) was constructed employing the SPSS software. A comparison between the ANN model and RMs in terms of their accuracy was carried out and the findings revealed that the accuracy of the ANN was higher than that of the RM.
Pencirian keseragaman campuran dan sifat reologi bahan suapan merupakan elemen penting dalam melaksanakan proses pengacuan suntikan seramik. Kesesuaian bahan suapan yang dibangunkan dapat mengurangkan masalah yang timbul ketika proses pengacuan suntikan, penyahikatan dan pensinteran. Justeru itu, kajian ini dijalankan untuk mengenal pasti pembebanan serbuk yang optimum berdasarkan kepada keseragaman campuran dan sifat reologi bahan. Pencirian keseragaman campuran ditentukan berdasarkan kepada nilai tork yang rendah dan berkeadaan mantap. Kajian reologi pula dilakukan dengan menggunakan mesin reometer rerambut. Ujian dijalankan pada julat suhu 150 dan 170oC dengan beban kenaan antara 20 dan 90 kgf. Bahan suapan yang digunakan terdiri daripada kombinasi serbuk seramik alumina-zirkonia bersama bahan pengikat polietilena berketumpatan tinggi, lilin parafin dan asid stearik. Hasil kajian menunjukkan bahan suapan bersifat pseudoplastik dengan pencampuran bahan yang seragam dalam tempoh kurang daripada 30 min. Hasil keputusan juga mendapati pada pembebanan serbuk 57% isi padu adalah yang paling optimum untuk proses pengacuan suntikan seramik berdasarkan kepada nilai kelikatan, indeks hukum kuasa dan tenaga pengaktifan aliran yang rendah.
The seeds of 6 × 6 half diallel progenies of Jatropha curcas were used to evaluate the effects of genotypes (parents and their hybrids) on germination traits of jatropha at Universiti Kebangsaan Malaysia. Germination traits were varied significantly (p<0.01) among the seeds of hybrids and their parents. The germination was started at four days after planting and prolonged until 15 days. Seed germination varied from 58.06 to 92.76% among the parents and 53.43 to 98.96% among the hybrids. The highest germination was observed in the hybrid P2 × P4 and none of the hybrid or parent showed complete (100%) germination. The maximum GI (germination index) and SVI (seedling vigour index) were found in the hybrids P1 × P5 and P1 × P2 and the lowest in P2 × P4 and P3 × P6, respectively. For most germination parameters parents behaved poorly than that of the hybrids.
Kesan suhu pensinteran terhadap sifat mekanik dan mikrostruktur bahan komposit alumina-zirkonia telah dikaji. Jasad
hijau alumina-zirkonia difabrikasi dengan menggunakan kaedah pengacuan suntikan seramik menggunakan sistem
bahan pengikat pelbagai komponen. Jasad perang yang terhasil selepas proses penyahikatan disinter pada suhu 1400,
1450, 1500, 1550, 1600 dan 1650°C selama 2 jam. Selanjutnya nilai ketumpatan, kekerasan dan keliatan patah bagi
jasad tersinter diukur. Mikrostruktur jasad tersinter ditentukan dengan menggunakan mikroskop imbasan elektron
(SEM). Kajian menunjukkan nilai ketumpatan, kekerasan dan keliatan patah bagi jasad tersinter meningkat sejajar
dengan peningkatan suhu pensinteran. Hasil uji kaji juga mendapati pada suhu pensinteran 1650°C sifat mekanik bahan
mencapai keadaan maksimum. Penumpatan jasad tersinter 98% menghampiri ketumpatan teori dengan nilai kekerasan
16.9 GPa dan keliatan patah mencecah 3.95 MPa.m1/2. Keputusan tersebut dapat dikaitkan dengan mikrostruktur bahan
yang padat didorong oleh tumbesaran ira yang lengkap.
Six parents (P1, P2, P3, P4, P5 and P6) half diallel population of Jatropha curcas were evaluated to determine the combining ability, genetic components of variance and heterosis for yield contributing traits. Diallel analysis showed that both additive and dominance gene action was responsible for the genetic regulation of all the traits under study. The cross combination P1 × P3 showed the highest positive specific combining ability for seed yield per plant. Combining ability results were also in close agreement with the findings of estimate of genetic components of variance. The seeds per fruit (89%) and 100-seed weight (93%) showed maximum narrow sense heritability. Seed yield per plant showed high mid parent (254.13%) and better parent (202.36%) heterosis in the cross combinations of P2 × P5 and P1 × P3, respectively.The parents of P1, P2, P3 and P5 were found to be superior for seed yield components when used in cross. Considering seed production for each plant, the hybrids P1 × P2, P1 × P3, P2 × P5 and P4 × P6 could be selected for the development of hybrid varieties.
Validity test is important during the development of ergonomics measurement. Failure to conduct validity tests will result in the measurement method being developed to be incapable of providing reliable ergonomics measurements. The objective of this study is to conduct validity test on the simple method ergonomics measurement which was developed. The method named Simple Ergonomics Risks Assessment (SERA). Content validity test and criterion validity test were conducted. The content validity test consists of 6 ergonomics experts who actively provide inputs and positive feedbacks to improve the measurement method being developed. Meanwhile, the criterion validity test involves data collection of complaints on body parts among oil palm workers which were derived from Nordic Musculoskeletal Questionnaire (NMQ) and ergonomics risk assessment scores obtained from SERA. Both findings were tested with the Chi-square test to explore possible relations between the two findings. Results from the test conducted showed that there are significant relations in the scores of neck posture; hip, right and left shoulder, right and left wrists and the right hand associated with fresh fruit bunch (FFB) harvesting activities. In the loose fruits collection, the Chi-square test showed significant relations in the scores of neck posture, hip, right and left shoulders, right wrist, right arm and the left hand. However, there are body parts such as the legs which showed no significant relation. More tests should be conducted to further explore the validity of the method being developed. Findings from both validity tests show that SERA were verified by the experts and tested with validated method so that it is valid to be applied in the future.