IF 0.4

Matematika Pub Date : 2023-12-30 DOI: 10.11113/matematika.v39.n3.1519

S. Ng

{"title":"An Almost Unbiased Regression Estimator: Theoretical Comparison and Numerical Comparison in Portland Cement Data","authors":"S. Ng","doi":"10.11113/matematika.v39.n3.1519","DOIUrl":"https://doi.org/10.11113/matematika.v39.n3.1519","url":null,"abstract":"Multicollinearity is the problem when there is linear dependency among the independent variables. The Ordinary least squares estimator (OLSE) that is commonly adopted is not suitable for the linear regression model when the independent variables are correlated. This is due to the high variance in OLSE and hence the accuracy of OLSE reduces in the presence of multicollinearity. Hence, the estimator named k-almost unbiased regression estimator (KAURE) was proposed as an alternative to OLSE in this paper. KAURE was developed by using the definition of an almost unbiased estimator to further reduce the bias of Liu-type estimator-special case (LTESC). The properties of KAURE including bias, variance-covariance and mean squared error (MSE) were derived. Theoretical comparison and real-life data comparison were carried out to evaluate the performance of the KAURE based on the MSE criterion. The application of the real-life data supported the theoretical comparison that showed the superiority of KAURE over OLSE and LTESC. The results revealed that KAURE could be considered as an alternative estimator for the linear regression model to combat the problem of multicollinearity.","PeriodicalId":43733,"journal":{"name":"Matematika","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139140198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Neutrosophic Bicubic Bezier Surface ApproximationModel for Uncertainty Data 不确定性数据的中性双三次贝塞尔曲面逼近模型

IF 0.4

Matematika Pub Date : 2023-12-28 DOI: 10.11113/matematika.v39.n3.1502

Siti Nur Idara Rosli, M. I. E. Zulkifly

引用次数: 0

Heat Transfer Enhancement of Convective Casson Nanofluid Flow by CNTs over Exponentially Accelerated Plate 瞬时加速板上的 CNT 增强卡松纳米流体对流的传热效果

IF 0.4

Matematika Pub Date : 2023-12-28 DOI: 10.11113/matematika.v39.n3.1509

W. N. N. Noranuar, A. Q. Mohamad, L. Y. Jiann, S. Shafie

{"title":"Heat Transfer Enhancement of Convective Casson Nanofluid Flow by CNTs over Exponentially Accelerated Plate","authors":"W. N. N. Noranuar, A. Q. Mohamad, L. Y. Jiann, S. Shafie","doi":"10.11113/matematika.v39.n3.1509","DOIUrl":"https://doi.org/10.11113/matematika.v39.n3.1509","url":null,"abstract":"Carbon nanotubes (CNTs) nanofluids are gaining increased popularity among researchers due to their outstanding thermal properties, leading to numerous promising industrial applications. Analytical solutions discovered in the study of CNTs nanofluids, combined with a Casson-type fluid model, are extremely limited. Therefore, a study on the heat transfer analysis of an unsteady and incompressible Casson carbon nanofluid flow is conducted. Human blood-based single-walled carbon nanotubes (SWCNTs) and human blood-based multi-walled carbon nanotubes (MWCNTs) are considered as nanofluids that move beyond an exponentially accelerated vertical plate. A set of dimensional momentum and energy equations, along with their initial and exponentially accelerated boundary conditions, is employed to represent the problem. The transformation of these equations to the dimensionless expression is achieved by using suitable dimensionless variables. The resulting equations are then tackled using Laplace transformation to acquire the analytical solution for temperature and velocity. Figures and tables are produced for a further analysis of temperature and velocity characteristics. The study shows that an increase in nanoparticle volume fraction enhances nanofluid flow and heat transmission, proving highly beneficial for cancer treatment. However, the flow is retarded due to the increment of Casson parameter values, while an enhancement is observed with a superior accelerating parameter.","PeriodicalId":43733,"journal":{"name":"Matematika","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139151197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Using the ARIMA/SARIMA Model for Afghanistan's Drought Forecasting Based on Standardized Precipitation Index 利用基于标准化降水指数的 ARIMA/SARIMA 模型进行阿富汗干旱预测

IF 0.4

Matematika Pub Date : 2023-12-28 DOI: 10.11113/matematika.v39.n3.1478

Reza Rezaiy, A. Shabri

{"title":"Using the ARIMA/SARIMA Model for Afghanistan's Drought Forecasting Based on Standardized Precipitation Index","authors":"Reza Rezaiy, A. Shabri","doi":"10.11113/matematika.v39.n3.1478","DOIUrl":"https://doi.org/10.11113/matematika.v39.n3.1478","url":null,"abstract":"Forecasting drought plays a vital role in strategic planning and the management of underground water supply. In this study, we utilized autoregressive integrated moving average (ARIMA) and Seasonal ARIMA (SARIMA) models to predict drought events in Afghanistan, based on the standardized precipitation index (SPI). We used monthly average precipitation data from 1991 to 2015 for model training, while data from 2016 to 2020 were employed for model validation. The results of the statistical analysis, which encompassed evaluating Mean Absolute Error (MAE), Root Mean Squared Error (RMSE), and Mean Absolute Percentage Error (MAPE), indicated that among the SPI 3, SPI 6, SPI 9, SPI 12, and SPI 24, the SARIMA models applied to the SPI 24 demonstrated the most accurate forecasting performance with RMSE (0.1492), MAE (0.1039), and MAPE (22.3732%) compared to SPI 3, SPI 6, SPI 9, and SPI 12. Subsequently, the ARIMA/SARIMA models were employed to forecast drought events for the upcoming year. It’s noteworthy that this constitutes the first-ever statistical analysis of the drought index in Afghanistan. Therefore, the outcomes of this study can be applied across diverse sectors, including water resource management and environmental precautions.","PeriodicalId":43733,"journal":{"name":"Matematika","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139150495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Biclustering Models Under Collinearity in Simulated Biological Experiments 模拟生物实验中相关性条件下的双聚类模型

IF 0.4

Matematika Pub Date : 2023-11-30 DOI: 10.11113/matematika.v39.n3.1461

Chibuike Nnamani, Norhaiza Ahmad

{"title":"Biclustering Models Under Collinearity in Simulated Biological Experiments","authors":"Chibuike Nnamani, Norhaiza Ahmad","doi":"10.11113/matematika.v39.n3.1461","DOIUrl":"https://doi.org/10.11113/matematika.v39.n3.1461","url":null,"abstract":"Biclustering models allow simultaneous detection of group observations that are related to variables in a data matrix. Such methods have been applied in biological data for classification. Collinearity is a common feature in biological data as there exist interactions between genes and proteins in their respective pathways. Such relationships could seriously reduce the efficiency of biclustering models. In this study, synthetic data are generated to investigate the effect of collinearity on the performance of biclustering models. Specifically, the data are generated and induced with varying degrees of collinearity using Cholesky decomposition, and are implanted with biclusters to produce different sets of synthetic data. The effectiveness of three models namely Biclustering by Cheng and Church (BCCC), Spectral Bicluster (BCSpectral) and Plaid Model in correctly detecting three types of biclusters in the generated data matrix were compared. The results show that all the models investigated are sensitive to changes in the level of collinearity. At low collinearity, all biclustering models were able to detect the implanted biclusters in the data correctly. As the level of collinearity in the data rise, the proportion of detectedbiclusters captured by the models reduces. In particular, BCC outperformed the other two models for moderate to high collinearity with a Jaccard coefficient of 0.499 to 0.875 and 0.746 to 0.936 for one and two implanted biclusters respectively.","PeriodicalId":43733,"journal":{"name":"Matematika","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139206987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Multi-Population O’Hare with ARIMA, ARIMA-GARCH and ANN in Forecasting Mortality Rate 使用 ARIMA、ARIMA-GARCH 和 ANN 预测死亡率的多人口奥黑尔模型

IF 0.4

Matematika Pub Date : 2023-11-30 DOI: 10.11113/matematika.v39.n3.1496

Nurul Syuhada Samsudin, Siti Rohani Mohd Nor

{"title":"Multi-Population O’Hare with ARIMA, ARIMA-GARCH and ANN in Forecasting Mortality Rate","authors":"Nurul Syuhada Samsudin, Siti Rohani Mohd Nor","doi":"10.11113/matematika.v39.n3.1496","DOIUrl":"https://doi.org/10.11113/matematika.v39.n3.1496","url":null,"abstract":"Multi-population mortality model has gained attention from prominent researchers of mortality due to its ability to provide biologically reasonable forecast. Previously, many researchers have proposed several multi-population stochastic mortality models that they considered adequate to produce accurate life expectancy. However, little have been addressed of the variability in full ages and time, which can contribute to an erroneous estimation of life expectancy. Therefore, this study proposed a new multi-population O’Hare with ARIMA, ARIMA-GARCH and ANN in forecasting the mortality rate for male and female in Malaysia, Taiwan, Japan, Hong Kong, Australia, USA, UK, Canada, and Switzerland. Multi-population O’Hare was used as a reference model, whilst ARIMA, ARIMA-GARCH and ANN were incorporated to the reference model to forecast the mortality rates. The adequacy of the proposed model was assessed by using measurement errors which were Mean Absolute Percentage Error (MAPE) and Root Mean Square Error (RMSE). The results showed by multi-population O’Hare with ARIMA-GARCH gave the best forecasting performance for Taiwan, Japan, Australia, USA, UK, Canada, and Switzerland. On the other hand, multi-population O’Hare with ARIMA gave the best forecasting performance for Malaysia, whereas multi-population O’Hare with ANN gave the best forecasting performance for Hong Kong.","PeriodicalId":43733,"journal":{"name":"Matematika","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139208656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Predicting Top Five Cryptocurrency Prices via Linear Structural Time Series (STS) Approach 通过线性结构时间序列(STS)方法预测五大加密货币价格

IF 0.4

Matematika Pub Date : 2023-04-15 DOI: 10.11113/matematika.v39.n1.1444

Nur Maisarah Abdul Rashid, M. Ismail, Noor Wahida Md Junus

{"title":"Predicting Top Five Cryptocurrency Prices via Linear Structural Time Series (STS) Approach","authors":"Nur Maisarah Abdul Rashid, M. Ismail, Noor Wahida Md Junus","doi":"10.11113/matematika.v39.n1.1444","DOIUrl":"https://doi.org/10.11113/matematika.v39.n1.1444","url":null,"abstract":"Predicting cryptocurrency prices are difficult due to dynamic data. At the same time, the hidden market behavior of trend and seasonal components in the history data is also critical as it provides an idea of what the price pattern will be in the future. Hence, this research proposes to identify and model the hidden pattern behavior in terms of component time series instead of removing it via the linear structural time series (STS) model approach. This study focuses on the top five cryptocurrencies relying on the highest market capitalization. From the results obtained, the top five cryptocurrencies have a different trend model, either deterministic or stochastic, which relies on the behavior of data. The five cryptocurrencies also show the crypto winter event, where the trend is downward after six months every year. The linear STS is the best model for predicting three cryptocurrencies’ prices for nonstationary and volatility data behavior. It can also handle the hidden component behavior and is easy to interpret. Since the linear STS model can indirectly retain the information of data, it will assist investors and traders in accurately predicting cryptocurrency prices.","PeriodicalId":43733,"journal":{"name":"Matematika","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42714395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Wall Shear Stress Distribution of non-Newtonian Blood Flow in Stenosed Bifurcated Artery 狭窄分叉动脉非牛顿血流的壁剪应力分布

IF 0.4

Matematika Pub Date : 2023-04-15 DOI: 10.11113/matematika.v39.n1.1452

Norliza Mohd Zain, Z. Ismail, Muhammad Sabaruddin Ahmad Jamali, Y. J. Lim

引用次数: 0

Backward Bifurcation and Hysteresis in a Mathematical Model of COVID19 with Imperfect Vaccine 具有不完全疫苗的covid - 19数学模型的后向分岔和滞后

IF 0.4

Matematika Pub Date : 2023-04-15 DOI: 10.11113/matematika.v39.n1.1458

Solomon Isa Rwat, Noor Atinah Ahmad Ahmad

引用次数: 1

Integration of Data Envelopment Analysis with Analytical Hierarchy Process and Entropy Measurement in the Optimization of Supplier Selection 供应商选择优化中的数据包络分析与层次分析法和熵测度相结合

IF 0.4

Matematika Pub Date : 2023-04-15 DOI: 10.11113/matematika.v39.n1.1391

Nur Rasyida Mohd Rashid, Bushra Abdul Halim, Iskandar Shah Mohd Zawawi, Husna Nadzirah Abdullah, Nur Iylia Antasha Abu Hassan, Nur Atikah Ismail

{"title":"Integration of Data Envelopment Analysis with Analytical Hierarchy Process and Entropy Measurement in the Optimization of Supplier Selection","authors":"Nur Rasyida Mohd Rashid, Bushra Abdul Halim, Iskandar Shah Mohd Zawawi, Husna Nadzirah Abdullah, Nur Iylia Antasha Abu Hassan, Nur Atikah Ismail","doi":"10.11113/matematika.v39.n1.1391","DOIUrl":"https://doi.org/10.11113/matematika.v39.n1.1391","url":null,"abstract":"Supplier selection is perceived as important decision-making process in any supply chain management. In this study, the best supplier for a company is being determined based on five main criteria chosen which are delivery, capacity, warranty, cost, and quality. The Analytic Hierarchy Process (AHP) and Entropy Measurement (EM) methods are integrated with Data Envelopment Analysis (DEA) was applied to set ranking and choose the best supplier as conventional DEA is not able to provide complete ranking among inefficient units. The mathematical modelling is executed using LINGO software. Supplier 3 has obtained efficient result of score 1 for both hybrid method and in Super Efficiency method as the most efficient supplier. Then, the results are validated using Spearman’s Rank Correlation Coefficient (SRCC) which shows positive correlation between both integrated methods. Finally, findings of this study indicate the feasibility of integrated AHP-DEA and EM-DEA for supplier selection with multiple criteria.","PeriodicalId":43733,"journal":{"name":"Matematika","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2023-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41851194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

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