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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
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Journal of Science and Technology
Number of Followers: 2  

  This is an Open Access Journal Open Access journal
ISSN (Print) 2229-8460
Published by Universiti Tun Hussein Onn Malaysia Homepage  [2 journals]
  • A Bayesian Parametric Estimation of Beta Kumaraswamy Burr Type X (Beta
           Kum-BX) Distribution Based on Cure Models with Covariates

    • Authors: Umar Yusuf Madaki, Mohd Rizam Abu Bakar
      Pages: 1 - 22
      Abstract: In statistical models for censored survival data which includes a proportion of individuals who are not subject to the event of interest under study are known as the long-term survival cured models. It has two most adopted and common models used in estimating the cure fraction namely: the mixture (standard cure) and the non-mixture models. In this research work, we introduce a Bayesian approach using the two models for survival data based on the beta Kumaraswamy Burr Type X distribution with six parameters and compared with two existing models: beta-Weibull and beta-generalized exponential distributions in analyzing a real-life dataset. The proposed approach allows the inclusion of covariates in the model. The parameter estimation was obtained by maximum likelihood and Bayesian analysis methods. The win Bugs and MCMC pack library in R softwares were employed for the Gibbs sampling algorithm in other to obtain the posterior summaries of interest and also the trace plots by the applying of real data sets and a simulation study was done based on cure models to compare the performance of both models relating to actual sense of motivation and novelty which clarifies the usefulness of the proposed methodologies.
      PubDate: 2022-06-28
      Issue No: Vol. 14, No. 1 (2022)
       
  • Optimal Control of a Three-State Diabetic Population Model with
           Interventions

    • Authors: Hanis Nasir
      Pages: 23 - 28
      Abstract: This paper studies an optimal control problem to describe the population dynamics of diabetes in the presence of intervention effects. We propose two control variables representing the interventions to reduce the incidence of diabetes, and the interventions to reduce the incidence of complications. By applying the optimal control theory, we seek to minimize the relative cost associated with the intervention efforts and to reduce the total number of people with diabetes. The solution to the optimality system is approximated by using the Forward-Backward Sweep Method. The numerical simulations show that the number of diabetics who develop complications can be reduced by adopting optimal control strategies.
      PubDate: 2022-06-28
      Issue No: Vol. 14, No. 1 (2022)
       
  • Temperature Variability Comparison Using Mann-Kendall Test

    • Authors: Oluseyi Ogunsola, Dilau; K.A., Ayokunnu. O.D.
      Pages: 29 - 36
      Abstract: Climate change in terms of extreme temperature has been a global concern, and Nigeria has not been an exception. However, analysis of climatic trend comparison between the northern and southern part of Nigeria, especially in terms of temperature variability is rarely found among the available works of literature. Thus, this work therefore analyzed and compared the average temperature trends of six stations each from the far north and south of Nigeria for 30 years (1981 to 2010) using statistical analysis and the Mann-Kendall test, as a nonparametric procedure in assessing the temperature trends. However, from the results of the analysis, it was observed that at a 1% significance level, the Mann-Kendall test of the temperature trend in all the six stations considered from the south was rising significantly, while for those in the north there was no significant temperature rise in five of the six stations considered which nevertheless dropped to four stations at 5% significant level. Moreover, correlations were observed to exist only amongst stations with significant temperature trends. Hence, based on this observation, it can be concluded that the climate in the southern part of Nigeria is more prone to extreme temperature variation than that of the northern part.
      PubDate: 2022-06-28
      Issue No: Vol. 14, No. 1 (2022)
       
  • Introduction of Ostrowski Homotopy Continuation Method for Solving
           Nonlinear Equations using Mathematica

    • Authors: Hafizudin Mohamad Nor, Asma Izzati Asnor, Zainor Ridzuan Yahya, Muhammad Zaini Ahmad
      Pages: 37 - 43
      Abstract: The solution to a nonlinear equation is found in this study by combining a classical and a powerful method. Basically, it is well known that the homotopy continuation method (HCM) is a powerful method that has been used for solving the problem of the classical method. A new approach is introduced in this study which is known as the Ostrowski Homotopy Continuation method (Ostrowski-HCM) with a purpose to overcome the divergence problem that arises from the classical Ostrowski’s method when a bad initial guess is used. To put it simply, when the derivative of a given function at the starting point is equal to zero, the problem arises. As a result, the division by zero renders the scheme invalid. In addition, a mathematical software, Mathematica 7.0, is used to implement the Ostrowski-HCM results. Thus, from the analysis of the results, it is proven that the Ostrowski-HCM is reliable and advantageous for solving the nonlinear equation.
      PubDate: 2022-06-28
      Issue No: Vol. 14, No. 1 (2022)
       
  • Forecasting of Malaysia Gold Price with Exponential Smoothing

    • Authors: Nur Amalina Shafie, Heidi Airisha Abdul Rahman, Muhammad Firdaus Ros Azizi, Muhammad Fahmi Saruand
      Pages: 44 - 50
      Abstract: Gold is a precious asset has attracted the investors to invest. Investors has interest to know the basic knowledge about gold price and the prediction price. Prediction price will help the investors to determine the benchmark of the gold price. However, various method can be predicting the price. Therefore, the objective of this study to determine the best model to forecast the Malaysia gold price. This study focus used Exponential Smoothing (ETS) forecasting models which are Single Exponential Smoothing (SES), Double Exponential Smoothing (DES), and Holt-Winters Exponential Smoothing. The best model is used to forecast the gold price in Malaysia for the next 12 months by using data from March 2016 until February 2021.The best model is determined by choosing the lowest Root Mean Squared Error (RMSE) value. The outcome for the lowest RMSE shows that DES is the best model for forecasting the gold price in Malaysia for the next 12 months. The result of the forecasting shows that the gold price will decrease from March 2021 until February 2022, and this could be due to the COVID-19 pandemic in Malaysia. Therefore, it will be a good opportunity for investors to buy gold in this period since the price is decreased and investors can sell it at the highest price in the future.
      PubDate: 2022-06-28
      Issue No: Vol. 14, No. 1 (2022)
       
  • Detection of Low Dose-Gamma Irradiated Spices by Photostimulated
           Luminescence (PSL) Technique

    • Authors: Farha Mizana Shamsudin, Muhamad Samudi Yasir
      Pages: 51 - 57
      Abstract: Photostimulated luminescence (PSL) has been widely used as a rapid screening technique for the detection of various irradiated foods. This study aims to investigate the efficacy of the PSL technique in the detection of low dose-gamma irradiated spices available in the Malaysia market. Samples of clove, coriander, fenugreek, turmeric powder and curry powder were irradiated at very low doses; 0 (control), 0.2, 0.5 and 1 kGy using Cobalt-60 as a source. PSL measurements and analysis were undertaken under subdued lighting following EN 13751 methods. The PSL value in the form of photon counts (PCs/60s) of all samples as a function of the irradiation dose after 7 days of storage were determined which revealed that the PSL value increases proportionally to the radiation dose applied. The PSL also was able to discriminate between the non-irradiated (<700 PCs/60s, negative) and irradiated (>5000 PCs/60s, positive) samples after 7 days of storage. Coriander generates the highest PCs at the lowest dose (0.2 kGy) and highest dose (1 kGy) after that storage period. The PSL value of all spice samples is considered accurate and consistent at all irradiation doses. This technique is highly reliable for the detection of irradiated spices available in the Malaysia market.
      PubDate: 2022-06-28
      Issue No: Vol. 14, No. 1 (2022)
       
  • Oxidation of Pear Seed Oil During Storage

    • Authors: Abel Otache, Amaebino Obi, Stella Chinelo, Christopher Ejeomo, Enakireru Davis Bobby, Esemedafe Josephine Ufuoma
      Pages: 58 - 66
      Abstract: The effects of storage on the oxidative deterioration of crude Pear Seeds Oil (PSO), obtained by soxhlet extraction, were studied. Oxidation was monitored after 6 months via several analytical techniques: peroxide value, iodine value, free fatty acids, Fourier-transform infrared spectroscopy (FTIR), and Gas chromatography–mass spectrometry (GC-MS). The slow detorioration of the oil was an indication that oxidation was strongly dependent on temperature, oxygen availability and the presence of Cu2+. The mass spectra from the GC-MS results reveal the formation of secondary oxidation products, thereby denoting a transformation of primary hydroxyperoxides. This assertion is further strengthen based on the increasing value of the total Saturated Fatty Acids (SFA) from 26.09 to 29.44 % and a corresponding decrease for Unsaturated Fatty Acid (UFA) from 71.28 to 68.80 %. Other physicochemical analysis, shows that an average Iodine value recorded a reduction from 40.377 to 39.193 at a rate of 2.9 %, free fatty acid also recorded an increase at 15.18 %. Furthermore, the acid value also recorded a 2.60 % reduction. An increase in the peroxide value from 6.243 to 7.452 at a rate of 16.22 %, is a confirmation of possible formation of secondary oxidation products as revealed by the GC-MS mass spectra. Therefore the need to pay close attention during production, transportation as well as the presence of possible Cu2+ is key to addressing slow oxidation that is capable of impairing the quality of the oil.
      PubDate: 2022-06-28
      Issue No: Vol. 14, No. 1 (2022)
       
  • Comparison of Tool Wear Mechanisms during Drilling of Aluminium Alloy 7075
           in Dry and Chilled Air Conditions

    • Authors: Nur Munirah Meera Mydin, Aishah Najiah Dahnel, Natasha A. Raof, Norkhairusshima Muhamad Khairussaleh, Suhaily Mokhtar
      Pages: 67 - 74
      Abstract: Aluminium alloys are widely used in manufacturing industry due to the need of lightweight components and low production cost. However, mechanical assembly of the alloy which requires drilling operations is challenging due to chip accumulation and heat at the cutting tool and workpiece interface. This often causes material adhesion on cutting edges, built-up edge, accelerated tool wear, shorter tool life and poor drilled hole quality. This paper investigates the effect drilling conditions (dry and chilled air at 10°C) on the wear mechanisms of tungsten carbide cutting tools during drilling Aluminium alloy 7075 (Al 7075) at two different feed rates. Chilled or cold air was used as a cooling medium in drilling Al 7075 to promote green manufacturing. Drilling operations of Al 7075 were performed at a constant cutting speed of 123 m/min with feed rates of 0.01 and 0.1 mm/rev. The cutting tools’ flank wear were measured using an optical microscope with Dino-Capture software and further examination on the tool wear (e.g., built-up edge, built-up layer, and crack) were conducted using Scanning Electron Microscopy (SEM). The results of this study indicate that at higher feed rate of 0.1 mm/rev, adhesive wear is dominant due to the presence of evident material adhesion and fractures on the cutting edges. The use of chilled air was found to cause less material adhesion, however more edge fracture occurred which could be due to workpiece hardening. Therefore, it is inferred that drilling Al 7075 with chilled air requires harder and stronger cutting tool in order prolong the tool life.
      PubDate: 2022-06-28
      Issue No: Vol. 14, No. 1 (2022)
       
  • Impact of Provenance on Phytochemical Attributes of pigmented Landrace
           Maize Varieties

    • Authors: James Majamanda, Mangani Katundu, Victoria Ndolo, David Tembo
      Pages: 75 - 82
      Abstract: Maize is one of the most diverse cereal crops that contribute highly in calorie supply to human diet. Pigmented maize secondary metabolites which are phytochemicals of healthy importance include carotenoids and phenolics which act as precursors of vitamin A and antioxidants respectively. Pigmented landrace maize is cultivated by smallholder farmers in their localities. Three different pigmented maize varieties from different growing districts were analysed for total carotenoids content (TCC) and total phenolic content (TPC), using spectrophotometer. The districts experience a warm temperate climate and higher rainfall in summer than in winter but they differ in that Ntcheu has highest average annual temperature of 20.3°C while Dedza receives the highest annual precipitation of about 1010 mm. Mzimba has an average annual temperature of 20.1°C and receives about 915 mm of precipitation annually. Individual carotenoids were analysed using high performance liquid chromatography (HPLC). TCC were significantly higher (p < 0.05) in Ntcheu and Mzimba provenances compared to Dedza. Lutein (22.84 ± 1.25 µg/g) and Zeaxanthin (23.16 ± 2.44 µg/g) were highest in landrace orange maize from Ntcheu. Mzimba provenance showed highest beta-cryptoxanthin (8.60 ± 2.15 µg/g). TPC were not significantly different between Dedza (204.29 ± 0.35 mg/Kg) and Mzimba (207.65 ± 0.22 mg /kg) red maize. Ntcheu provenance showed the least TPC (184.06 ± 0.61 mg/Kg). It seems provenance influenced phytochemical attributes of pigmented landrace maize varieties in some instances. This study also revealed that post-harvest handling of pigmented landrace maize affects phytochemical content. Care should, therefore, be taken in handling pigmented landrace maize to avoid phytochemical loses. Farmers and all other stakeholders in Malawi are encouraged to produce and include pigmented landrace maize varieties in their diets in order to gain the associated health benefits. Further studies are needed for complete characterisation of phenolic compounds of pigmented landrace maize of Malawi.
      PubDate: 2022-06-28
      Issue No: Vol. 14, No. 1 (2022)
       
 
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