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0.98[(Na(1–x)/2Smx/2Nb0.3TiO3)] + 0.02MnO2 Lead-free Ceramic System Design; An antiferroelectrics with Improved Relaxation Behavior
(Elsevier BV, 2023) Emmanuel, Marwa
The sodium niobate-based ceramics 0.98[(Na(1−x)/2Smx/2Nb0.3TiO3)] + 0.02MnO2 acronymed NSmNT of different compositions (x = 0.05, 0.1, 0.11, 0.12, and 0.13) were prepared via solid-state reaction method. The prepared samples were characterized by XRD to study the phase structure of the designed systems, SEM to study the microstructure properties of the NSmNT ceramics. In addition to that LCR meter was used to measure the sample temperature-dependent dielectric permittivity, dielectric loss, and systems impedance. The results showed an increment in the dielectric breakdown strength (DBS) with increasing x content from 100 kVcm–1 to 450 kVcm–1. Similarly, the high recoverable energy density (Wrec) of 5.61 J cm–3 was obtained for x = 0.11 symbolized (NSmNT2) with an exquisite efficiency of 88%. The study also analyzed the complex impedance of the NSmNT2 ceramics system to clearly understand the dielectric behavior of the system in question. A general view of things considers the NSmNT2 ceramic system to be a reliable system for pulsed power applications.
0.98[(Na(1–x)/2Smx/2Nb0.3TiO3)] + 0.02MnO2 Lead-free ceramic system sesign; an antiferroelectrics with improved relaxation behavior
(Elsevier BV, 2023) Emmanuel, Marwa
The sodium niobate-based ceramics 0.98[(Na(1−x)/2Smx/2Nb0.3TiO3)] + 0.02MnO2 acronymed NSmNT of different compositions (x = 0.05, 0.1, 0.11, 0.12, and 0.13) were prepared via solid-state reaction method. The prepared samples were characterized by XRD to study the phase structure of the designed systems, SEM to study the microstructure properties of the NSmNT ceramics. In addition to that LCR meter was used to measure the sample temperature-dependent dielectric permittivity, dielectric loss, and systems impedance. The results showed an increment in the dielectric breakdown strength (DBS) with increasing x content from 100 kVcm–1 to 450 kVcm–1. Similarly, the high recoverable energy density (Wrec) of 5.61 J cm–3 was obtained for x = 0.11 symbolized (NSmNT2) with an exquisite efficiency of 88%. The study also analyzed the complex impedance of the NSmNT2 ceramics system to clearly understand the dielectric behavior of the system in question. A general view of things considers the NSmNT2 ceramic system to be a reliable system for pulsed power applications.
2-Hexylthiophene-substituted alizarin-based (D–π–A) organic dyes for dye-sensitized solar cell applications:: density functional theory and UV–Vis studies
(Science Reviews Ltd., 2021) Abubakari, I.; Babu, S.; Vuai, S.; Makangara, J.
This work reports density functional theory and time-dependent density functional theory calculations of the optimized geometries, electronic structures and optical properties of molecular dyes D1, D2, D3, D4, D5, and D6 formulated through substitution of 2-hexylthiophene to alizarin using the hybrid functional B3LYP and 6-31G (d,p) basis sets. The dyes are considered as potential pigments for dye-sensitized solar cells. For all dyes, HOMO/LUMO (Highest Occupied Molecular Orbital/Lowest Unoccupied Molecular Orbital) analysis results in positive outcomes upon electron injection to semiconductors and subsequent dye regeneration by the electrolyte. It is found that charge transfer is from the thiophene and unsubstituted ring of alizarin to the substituted ring of alizarin containing C=O and OH groups. The C=O groups are observed to be very important in strengthening the dyes as they are revealed to be the anchoring group bonding to the TiO2 semiconductor. Comparatively, dye D6 is observed to possess high absorption ability and electron injection power through a study of the light-harvesting efficiency and injection driving force (ΔGinject). The estimated values of open-circuit voltage (Voc) for the computed dyes are also presented. Decisively, all the considered dyes prove to be useful as potential photosensitizers in solar cells using a TiO2 semiconductor and I I− −/ 3 coupling electrolyte.
A combined theoretical and experimental study of nickel derivative [Daiquiris(nicotinamide-jN1)nickel (II)]-lfumarato-K2O1:O4
(World Scientific Pub Co Pte Ltd, 2023) Pandey, Anoop Kumar; Chand, Satish; Diwedi, Apoorva; Singh, Vijay; Singh, Vinod Kumar; Mishra, Vijay Narayan
The ground state geometry of the nickel derivative [Daiquiris(nicotinamide-jN1) nickel(II)]-fumarato-K2O1:O4 has been optimized and is being led toward its quantum chemical analysis in this paper. For more accuracy, we used the 6-311[Formula: see text]G (d, p) basis set for C, H, N, and O atoms and the LAN2DZ basis set for Ni. The calculated and experimental infrared (IR) spectra for the title molecule are well correlated, and the correlation factor [Formula: see text] shows that the method effectively interprets the molecule’s IR spectra. The electronic properties such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and associated energy gap have been calculated by Time-Dependent Density Functional Theory (TD-DFT) approach. The natural bond orbital (NBO) analysis of the molecule describes how interatomic charge transfer results in the formation of bonding–nonbonding interactions. The experimental and calculated Ultraviolet visible (UV-Vis) spectra are compared. We anticipate our work will inspire fresh approaches to the title molecule’s ongoing research.
A finite difference study of radiative mixed convection MHD heat propagating Casson fluid past an accelerating porous plate including viscous dissipation and Joule heating effects
(Elsevier BV, 2024) Reddy, B. Prabhakar; Matao, P.M.; Sunzu, J.M.
A finite difference numerical simulation scrutiny is executed to evaluate the combined impacts of heat generation, buoyancy forces, viscous dissipation and Joule heating in unsteady hydro-magnetic mixed convective chemically reactive and radiative Casson fluid flowing along an exponentially accelerating permeable vertical plate engrossed in a porous media by considering ramp surface concentration and temperature. The dimensionless non-linear coupled PDEs describing the flow model are dealt numerically by adopting the competent implicit Crank-Nicolson finite difference procedure. The variance of velocity, temperature, and concentration distributions are exposed via graphical representations due to the dissimilarity of the flow restrained parameters. Computational outcomes of the skin-friction, Nusselt and the Sherwood numbers are portrayed in the tabular pattern. The final outcomes of the research exposed that the impacts of thermal radiation, viscous dissipation, and heat production parameters enlarges the temperature and velocity distributions. The fluid motion deflates for growing Casson parameter and magnetic field intensity. The rising chemical reaction parameter suppresses the concentration and velocity distributions. Very importantly it is distinguished that fluid momentum, temperature, and concentration are quicker in the instance of isothermal plate temperature than ramp wall temperature. This kind of research may find specific industrial and medical utilizations such as glass manufacturing, crude oil purification, lubrication, paper production, blood transport study in cardiovascular design, etc.
A finite difference study of radiative mixed convection MHD heat propagating Casson fluid past an accelerating porous plate including viscous dissipation and Joule heating effects
(Elsevier BV, 2024) Reddy, B. Prabhakar; Matao, P.M.; Sunzu, J.M.
A finite difference numerical simulation scrutiny is executed to evaluate the combined impacts of heat generation, buoyancy forces, viscous dissipation and Joule heating in unsteady hydro-magnetic mixed convective chemically reactive and radiative Casson fluid flowing along an exponentially accelerating permeable vertical plate engrossed in a porous media by considering ramp surface concentration and temperature. The dimensionless non-linear coupled PDEs describing the flow model are dealt numerically by adopting the competent implicit Crank-Nicolson finite difference procedure. The variance of velocity, temperature, and concentration distributions are exposed via graphical representations due to the dissimilarity of the flow restrained parameters. Computational outcomes of the skin-friction, Nusselt and the Sherwood numbers are portrayed in the tabular pattern. The final outcomes of the research exposed that the impacts of thermal radiation, viscous dissipation, and heat production parameters enlarges the temperature and velocity distributions. The fluid motion deflates for growing Casson parameter and magnetic field intensity. The rising chemical reaction parameter suppresses the concentration and velocity distributions. Very importantly it is distinguished that fluid momentum, temperature, and concentration are quicker in the instance of isothermal plate temperature than ramp wall temperature. This kind of research may find specific industrial and medical utilizations such as glass manufacturing, crude oil purification, lubrication, paper production, blood transport study in cardiovascular design, etc.
A fractional order model for the transmission dynamics of shigellosis
(Elsevier BV, 2024) Edward, Stephen
Shigellosis, a highly contagious bacterial infection causing diarrhea, fever, and abdominal pain, necessitates a deep understanding of its transmission dynamics to devise effective control measures. Our study takes a novel approach, employing a fractional order framework to explore the influence of memory and control measures on Shigellosis transmission dynamics, thereby making a unique contribution to the field. The model is presented as a system of Caputo fractional differential equations capturing time constant controls. The Caputo derivatives are chosen for their inherent benefits. The qualitative features of the model, such as the solutions' existence and uniqueness, positivity, and boundedness, are thoroughly investigated. Moreover, the equilibria of the model are derived and analyzed for their stability using suitable theorems. In particular, local stability was proved through Routh's criteria, while global stability results were established in the Ulam-Hyers sense. The model is then solved numerically with the help of the predict-evaluate-correct-evaluate method of Adams-Bashforth-Moulton. The numerical results underscore the significant impact of memory on disease evolution, highlighting the novelty of integrating memory-related aspects into the meticulous planning of effective disease control strategies. Using fractional-order derivatives is more beneficial for understanding the dynamics of Shigellosis transmission than integral-order models. The advantage of fractional derivatives is their ability to provide numerous degrees of freedom, allowing for a broader range of analysis of the system's dynamic behaviour, including nonlocal solutions. Also, an investigation on the impacts of control measures via parameter variation is done; the findings show that applying treatment and sanitation minimizes disease eruption.
A new cosine-originated probability distribution with symmetrical and asymmetrical behaviors: repetitive acceptance sampling with reliability application
(MDPI AG, 2023) Alshanbari, Huda M.; Rao, Gadde Srinivasa; Seong, Jin-Taek; Salem, Sultan; Khosa, Saima K.
Several new acceptance sampling plans using various probability distribution methods have been developed in the literature. However, there is no published work on the design of new sampling plans using trigonometric-based probability distributions. In order to cover this amazing and fascinating research gap, we first introduce a novel probabilistic method called a new modified cosine-G method. A special member of the new modified cosine-G method, namely, a new modified cosine-Weibull distribution, is examined and implemented. The density function of the new model possesses symmetrical as well as asymmetrical behaviors. The usefulness and superior fitting power of the new modified cosine-Weibull distribution are demonstrated by analyzing an asymmetrical data set. Furthermore, based on the new modified cosine-Weibull distribution, we develop a new repetitive acceptance sampling strategy for attributes with specified shape parameters. Finally, a real-world application is presented to illustrate the proposed repetitive acceptance sampling strategy.
A New Modification of the Weibull Distribution: Model, Theory, and Analyzing Engineering Data Sets
(MDPI AG, 2024) Alshanbari, H. M.; Ahmad, Z.; El-Bagoury, A. H.; Odhah, O. H.; Rao, G. S.
Symmetrical as well as asymmetrical statistical models play a prominent role in describing and predicting the real-world phenomena of nature. Among other fields, these models are very useful for modeling data in the sector of civil engineering. Due to the applicability of the statistical models in civil engineering and other related sectors, this paper offers a statistical methodology to improve the distributional flexibility of traditional models. The suggested method/approach is called the extended-X family of distributions. The proposed method has the ability to generate symmetrical and asymmetrical probability distributions. Based on the extended-X family approach, an updated version of the Weibull model, namely, the extended Weibull model, is studied. The proposed model is very flexible and has the ability to capture the symmetrical and asymmetrical shapes of its density function. For the extended-X method, the estimation of parameters, a simulation study, and some mathematical properties are derived. Finally, the practical illustration/usefulness of the suggested model is shown by analyzing two data sets taken from the field of engineering. Both data sets represent the fracture toughness of alumina (Al2O3).
A New Sine-Based Distributional Method with Symmetrical and Asymmetrical Natures: Control Chart with Industrial Implication
(MDPI AG, 2023) Alshanbari, Huda M.; Rao, Gadde Srinivasa; Seong, Jin-Taek; Khosa, Saima K.
Control charts are widely used in quality control and industrial sectors. Because of their important role, researchers are focusing on the development of new control charts. According to our study, there is no significant amount of published work on control charts using trigonometrically generated distribution methods. In this paper, we contribute to this interesting research gap by developing a new control chart using a sine-based distributional method. The proposed distributional method (or family of probability distributions) may be called a new modified sine-G family of distributions. Based on the new modified sine-G method, a novel modification of the Weibull distribution, namely, a new modified sine-Weibull distribution, is introduced. The new modified sine-Weibull distribution is flexible enough to capture symmetrical and asymmetrical behaviors of its density function. An industrial application is considered to show the importance and implacability of the proposed distribution in quality control. Based on the proposed model, an attribute control chart is developed under a truncated life test. The control chart limits (ARLs) are also computed for the proposed model. The ARLs of the proposed control chart are compared with the attribute control chart of the Weibull distribution. The results show that the developed chart is more efficient than the existing attribute control chart for the Weibull distribution.
A New Sine-Based Distributional Method with Symmetrical and Asymmetrical Natures: Control Chart with Industrial Implication
(MDPI AG, 2023) Alshanbari, Huda M.; Rao, Gadde Srinivasa; Seong, Jin-Taek; Khosa, Saima K.
Control charts are widely used in quality control and industrial sectors. Because of their important role, researchers are focusing on the development of new control charts. According to our study, there is no significant amount of published work on control charts using trigonometrically generated distribution methods. In this paper, we contribute to this interesting research gap by developing a new control chart using a sine-based distributional method. The proposed distributional method (or family of probability distributions) may be called a new modified sine-G family of distributions. Based on the new modified sine-G method, a novel modification of the Weibull distribution, namely, a new modified sine-Weibull distribution, is introduced. The new modified sine-Weibull distribution is flexible enough to capture symmetrical and asymmetrical behaviors of its density function. An industrial application is considered to show the importance and implacability of the proposed distribution in quality control. Based on the proposed model, an attribute control chart is developed under a truncated life test. The control chart limits (ARLs) are also computed for the proposed model. The ARLs of the proposed control chart are compared with the attribute control chart of the Weibull distribution. The results show that the developed chart is more efficient than the existing attribute control chart for the Weibull distribution.
A new statistical methodology using the sine function: Control chart with an application to survival times data
(Public Library of Science (PLoS), 2023) Kamal, Mustafa; Rao, Gadde Srinivasa; Alsolmi, Meshayil M.; Ahmad, Zubair; Aldallal, Ramy; Rahman, Md. Mahabubur; William Guo
Statistical methodologies have a wider range of practical applications in every applied sector including education, reliability, management, hydrology, and healthcare sciences. Among the mentioned sectors, the implementation of statistical models in health sectors is very crucial. In the recent era, researchers have shown a deep interest in using the trigonometric function to develop new statistical methodologies. In this article, we propose a new statistical methodology using the trigonometric function, namely, a new trigonometric sine-family of distribution. A subcase (special member) of the new trigonometric sine-method called a new trigonometric sine-Weibull distribution is studied. The estimators of the new trigonometric sine-Weibull distribution are derived. A simulation study of the new trigonometric sine-Weibull distribution is also provided. The applicability of the new trigonometric sine-Weibull distribution is shown by considering a data set taken from the biomedical sector. Furthermore, we introduce an attribute control chart for the lifetime of an entity that follows the new trigonometric sine-Weibull distribution in terms of the number of failure items before a fixed time period is investigated. The performance of the suggested chart is investigated using the average run length. A comparative study and real example are given for the proposed control chart. Based on our study of the existing literature, we did not find any published work on the development of a control chart using new probability distributions that are developed based on the trigonometric function. This surprising gap is a key and interesting motivation of this research.
A new statistical methodology using the sine function: Control chart with an application to survival times data
(Public Library of Science (PLoS), 2023) Kamal, Mustafa; Rao, Gadde Srinivasa; Alsolmi, Meshayil M.; Ahmad, Zubair; Aldallal, Ramy; Md. Rahman, Mahabubur; William Guo
Statistical methodologies have a wider range of practical applications in every applied sector including education, reliability, management, hydrology, and healthcare sciences. Among the mentioned sectors, the implementation of statistical models in health sectors is very crucial. In the recent era, researchers have shown a deep interest in using the trigonometric function to develop new statistical methodologies. In this article, we propose a new statistical methodology using the trigonometric function, namely, a new trigonometric sine-G family of distribution. A subcase (special member) of the new trigonometric sine-G method called a new trigonometric sine-Weibull distribution is studied. The estimators of the new trigonometric sine-Weibull distribution are derived. A simulation study of the new trigonometric sine-Weibull distribution is also provided. The applicability of the new trigonometric sine-Weibull distribution is shown by considering a data set taken from the biomedical sector. Furthermore, we introduce an attribute control chart for the lifetime of an entity that follows the new trigonometric sine-Weibull distribution in terms of the number of failure items before a fixed time period is investigated. The performance of the suggested chart is investigated using the average run length. A comparative study and real example are given for the proposed control chart. Based on our study of the existing literature, we did not find any published work on the development of a control chart using new probability distributions that are developed based on the trigonometric function. This surprising gap is a key and interesting motivation of this research.
A new statistical methodology using the sine function: Control chart with an application to survival times data
(Public Library of Science (PLoS), 2023) Kamal, Mustafa; Rao, Gadde Srinivasa; Alsolmi, Meshayil M.; Ahmad, Zubair; Aldallal, Ramy; Md. Rahman, Mahabubur; William Guo
Statistical methodologies have a wider range of practical applications in every applied sector including education, reliability, management, hydrology, and healthcare sciences. Among the mentioned sectors, the implementation of statistical models in health sectors is very crucial. In the recent era, researchers have shown a deep interest in using the trigonometric function to develop new statistical methodologies. In this article, we propose a new statistical methodology using the trigonometric function, namely, a new trigonometric sine-G family of distribution. A subcase (special member) of the new trigonometric sine-G method called a new trigonometric sine-Weibull distribution is studied. The estimators of the new trigonometric sine-Weibull distribution are derived. A simulation study of the new trigonometric sine-Weibull distribution is also provided. The applicability of the new trigonometric sine-Weibull distribution is shown by considering a data set taken from the biomedical sector. Furthermore, we introduce an attribute control chart for the lifetime of an entity that follows the new trigonometric sine-Weibull distribution in terms of the number of failure items before a fixed time period is investigated. The performance of the suggested chart is investigated using the average run length. A comparative study and real example are given for the proposed control chart. Based on our study of the existing literature, we did not find any published work on the development of a control chart using new probability distributions that are developed based on the trigonometric function. This surprising gap is a key and interesting motivation of this research.
A new trigonometric modification of the Weibull distribution: Control chart and applications in quality control
(Public Library of Science (PLoS), 2023) Alomair, Mohammed Ahmed; Ahmad, Zubair; Rao, Gadde Srinivasa; Al-Mofleh, Hazem; Khosa, Saima Khan; Al Naim, Abdulaziz Saud; Qichun Zhang
In the most recent era, the extensions of the probability models via trigonometry methods have received great attention. This paper also offers a novel trigonometric version of the Weibull model called a type-I cosine exponentiated Weibull (for short “TICE-Weibull”) distribution. The identifiability properties for all three parameters of the TICE-Weibull model are derived. The estimators of the TICE-Weibull model are derived by implementing the maximum likelihood approach. To demonstrate the effectiveness of the TICE-Weibull model, two applications from real-world phenomena are analyzed. In addition, the proposed statistical model is established for an attribute control chart based on a time-truncated life test. The advantage of the developed charts is examined based on the average run length (ARL). The necessary tables of shift sizes and various sample sizes are offered for numerous values of the distribution parameters, as well as specified ARL and shift constants. Some numerical examples are discussed for various scheme parameters to study the performance of the new TICE-Weibull attribute control charts. According to our search and a brief study of the statistical literature, there is no published work on the development of a control chart using new probability models that are introduced using the cosine function. This is the key motivation of this work, which fills this amazing and interesting research gap.
A new trigonometric modification of the Weibull distribution: Control chart and applications in quality control
(Public Library of Science (PLoS), 2023) Alomair, Mohammed Ahmed; Ahmad, Zubair; Rao, Gadde Srinivasa; Al-Mofleh, Hazem; Saima Khan Khosa; Al Naim, Abdulaziz Saud; Qichun Zhang
In the most recent era, the extensions of the probability models via trigonometry methods have received great attention. This paper also offers a novel trigonometric version of the Weibull model called a type-I cosine exponentiated Weibull (for short “TICE-Weibull”) distribution. The identifiability properties for all three parameters of the TICE-Weibull model are derived. The estimators of the TICE-Weibull model are derived by implementing the maximum likelihood approach. To demonstrate the effectiveness of the TICE-Weibull model, two applications from real-world phenomena are analyzed. In addition, the proposed statistical model is established for an attribute control chart based on a time-truncated life test. The advantage of the developed charts is examined based on the average run length (ARL). The necessary tables of shift sizes and various sample sizes are offered for numerous values of the distribution parameters, as well as specified ARL and shift constants. Some numerical examples are discussed for various scheme parameters to study the performance of the new TICE-Weibull attribute control charts. According to our search and a brief study of the statistical literature, there is no published work on the development of a control chart using new probability models that are introduced using the cosine function. This is the key motivation of this work, which fills this amazing and interesting research gap.
A queuing system model in the outpatient department of jinja regional referral hospital, Uganda
(The University of Dodoma, 2023) Kisakye, A.
This study investigated a queuing system model in the outpatient department of Jinja Regional Referral Hospital, Uganda. Primary data was obtained from JRRH for a period of one week. Observation method was used to record patient arrival times, service start times and service end times. The aim of the study was to identify a suitable distribution for arrival and service time of patients at the hospital, to identify the suitable distribution for waiting time of patients at the hospital and to compare the performance of a queueing model for arrival and service time of patients at the hospital with other existing models. The study findings showed that the Weibull and Gen. Extreme Value distribution acted as good fit for patient arrival and service time based on the AIC and BIC values. Also the findings based on waiting time showed that the Weibull distribution acted as a good fit for patient waiting time at the hospital according to the AIC and BIC values. The findings about the model showed that the G/G/3 model was the best as evidenced by the few expected number of patients in the queue which was 1 and 1, expected number of patients in the system which was 2 and 1, expected waiting time of patients in the queue 0.07minutes and 0.027 minutes and the expected waiting time of patients in the system which was 0.09 minutes and 0.005 minutes at both the registration counter and doctor’s rooms respectively. Therefore, Jinja Regional Referral Hospital might become a role model for other healthcare facilities by putting the recommendations into practice and looking into new research areas. This would improve the patient experience and the way healthcare is delivered there.
A Weighted Cosine-G Family of Distributions: Properties and Illustration Using Time-to-Event Data
(MDPI AG, 2023) Odhah, Omalsad Hamood; Alshanbari, Huda M.; Ahmad, Zubair; Rao, Gadde Srinivasa
Modeling and predicting time-to-event phenomena in engineering, sports, and medical sectors are very crucial. Numerous models have been proposed for modeling such types of data sets. These models are introduced by adding one or more parameters to the traditional distributions. The addition of new parameters to the traditional distributions leads to serious issues, such as estimation consequences and re-parametrization problems. To avoid such problems, this paper introduces a new method for generating new probability distributions without any additional parameters. The proposed method may be called a weighted cosine-G family of distributions. Different distributional properties of the weighted cosine-G family, along with the maximum likelihood estimators, are obtained. A special model of the weighted cosine-G family, by utilizing the Weibull model, is considered. The special model of the weighted cosine-G family may be called a weighted cosine-Weibull distribution. A simulation study of the weighted cosine-Weibull model is conducted to evaluate the performances of its estimators. Finally, the applications of the weighted cosine-Weibull distribution are shown by considering three data sets related to the time-to-event phenomena.
A Weighted Cosine-G Family of Distributions: Properties and Illustration Using Time-to-Event Data
(MDPI AG, 2023) Odhah, Omalsad Hamood; Alshanbari, Huda M.; Ahmad, Zubair; Rao, Gadde Srinivasa
Modeling and predicting time-to-event phenomena in engineering, sports, and medical sectors are very crucial. Numerous models have been proposed for modeling such types of data sets. These models are introduced by adding one or more parameters to the traditional distributions. The addition of new parameters to the traditional distributions leads to serious issues, such as estimation consequences and re-parametrization problems. To avoid such problems, this paper introduces a new method for generating new probability distributions without any additional parameters. The proposed method may be called a weighted cosine-G family of distributions. Different distributional properties of the weighted cosine-G family, along with the maximum likelihood estimators, are obtained. A special model of the weighted cosine-G family, by utilizing the Weibull model, is considered. The special model of the weighted cosine-G family may be called a weighted cosine-Weibull distribution. A simulation study of the weighted cosine-Weibull model is conducted to evaluate the performances of its estimators. Finally, the applications of the weighted cosine-Weibull distribution are shown by considering three data sets related to the time-to-event phenomena.
Aboveground carbon storage in Adansonia digitata L. (Baobab) in Mkanana agroforestry and Mangalisa forest reserve in Mpwapwa District, Tanzania
(MultiCraft, 2022) Mganga, Nyatwere Donasian; Yusuph, Khamis
Woodlands are important sinks for the ever increasing levels of atmospheric carbon dioxide, which is directly linked to climate change. Baobab (Adansonia digitata L.) is among the vascular tree species with a long lifespan of 1250 years thus potential for carbon storage though inadequately studied. This study therefore aimed to account for aboveground biomass and carbon in an agroforestry of Mkanana village (with baobabs and sunflower) and Mangalisa forest reserve in Mpwawa District. The allometric model developed for baobabs in dry areas was used for estimation of biomass which was computed as 50% carbon. The mean aboveground biomass of baobabs of 6.952 ± 0.09546 tonnes/tree in Mangalisa forest reserve was higher than 5.538 ± 0.3064 tonnes/tree recorded in Mkanana agroforestry (Mann-Whitney U-Statistic = 94.000, U’ = 531.00, P ˂ 0.0001). On the other hand, the mean aboveground carbon of 3.476 ± 0.09546 tonnes/tree in Mangalisa forest reserve was significantly higher than 2.769 ± 0.1533 tonnes/tree recorded in Mkanana agroforestry (Mann-Whitney U-Statistic = 93.000, U’ = 532.00, P ˂ 0.0001). The results of this study positively contribute to vegetation carbon storage. Sustainable carbon storage in baobabs can be achieved by planting them in reserve areas rather than in agroforestry.

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