Kemahiran mencongak dalam kalangan kanak-kanak

Pernahkah anda berhadapan dengan situasi seperti ini? Anda dan keluarga menjamu selera di sebuah restoran. Ketika ingin membayar, jumlah harga yang dinyatakan berbeza dari jumlah yang anda jangka. Anda meminta pekedai menyemak semula dan didapati jumlah yang disebutkan tadi salah lalu beliau memperbetulkan kesilapannya. Situasi ke dua, semasa membeli belah di pasar raya, anda terpaksa menurunkan beberapa barang dari troli kerana jumlah harga keseluruhan barang-barang dalam troli melebihi bajet yang telah anda tetapkan. Sebenarnya, kedua-dua situasi ini ada kaitan dengan kemahiran mencongak

Pelajar pulang ke kampus dalam situasi Covid-19. Bersediakah kita

Pandemik Covid-19 telah memberi kesan kepada seluruh pelosok dunia dari aspek ekonomi, pendidikan, sosial, budaya, gaya hidup, dan kesihatan mental. Pada 15 September 2021 sahaja, Malaysia telah mencatatkan jumlah kes aktif Covid-19 sebanyak 225,590. Langkah pencegahan seperti Perintah Kawalan Pergerakan (PKP) dan penjarakan sosial telah memberi impak yang besar kepada sistem pendidikan negara. Universiti-universiti dan kolej-kolej terpaksa menggantung operasi kelas fizikal dan beralih kepada pengajaran dan pembelajaran dalam talian, manakala kebanyakan pekerja dan staf terpaksa bekerja dari rumah

Oxi-P GUI: A Graphical User Interface (GUI) for wastewater treatment process in oxidation pond

The wastewater treatment process is aimed to reduce pollution to the appropriate level. An oxidation pond system can treat contaminants in wastewater. Oxidation ponds are use sunlight, bacteria, and algae to treat wastewater. This study developed an improved mathematical model and a graphical user interface (GUI), called oxi-P GUI to predict the wastewater treatment process in an oxidation pond. The correlation between dissolved oxygen (DO), chemical oxygen demand (COD), coliform bacteria, as well as concentrations of phototrophic bacteria (PSB) were examined. In MATLAB software, a revised model consisting of ordinary differential equations (ODEs) set of integrating the Monod equation was numerically solved utilising the fourth order Runge-Kutta method. The current model's root mean square error (RMSE) values were compared to the suggested model's RMSE values for model validation. The model offered a more accurate estimate than the existing model of changes in the amount of concentration in oxidation pond, which was necessary to produce acceptable water quality. A wastewater management personnel may use GUI to track water quality and determine the most effective wastewater treatment mechanism. Additionally, this user-friendly GUI will give a better understanding about the treatment process, especially to people with less programming skills

A modified predictive model for colour changes in French fries during frying

During frying, heat and mass transfer phenomena happen and cause the physiochemical changes that affect the colour of french fries. Moisture content, oil content, and colour are important quality parameters in frying french fries, while temperature, frying time, and sample thickness will affect the french fries. In this study, we developed a modified mathematical model for colour changes of French fries during frying. The colour changes were formulated using a first-order ordinary differential equation that was solved using the 4th order Runge-Kutta method in the MATLAB software. The formulation for rate constant was modified using the Arrhenius equation and the sum squared error (SSE) of the proposed model was compared with the SSE of existing models. The colour was evaluated based on two parameters which are oil temperature (150°C, 170°C, 190°C) during frying and sample thickness (5 mm,10 mm, 15 mm) of french fries. The results showed that incorporating the factor of moisture into the model provides a better prediction of lightness and yellowness of french fries during frying. Overall, we conclude that moisture plays a significant role in the colour changing of french fries

Simulation of COVID-19 outbreaks via graphical user interface (GUI)

Background: This research aimed to model the outbreak of COVID-19 in Malaysia and develop a GUI-based model. Design and methods: The model is an improvement of the susceptible, infected, recovery, and death (SIRD) compartmental model. The epidemiological parameters of the infection, recovery, and death rates were formulated as time dependent piecewise functions by incorporating the control measures of lockdown, social distancing, quarantine, lockdown lifting time and the percentage of people who abide by the rules. An improved SIRD model was solved via the 4th order Runge-Kutta (RK4) method and 14 unknown parameters were estimated by using Nelder- Mead algorithm and pattern-search technique. The publicly available data for COVID-19 outbreak in Malaysia was used to validate the performance of the model. The GUI-based SIRD model was developed to simulate the number of active cases of COVID-19 over time by considering movement control order (MCO) lifted date and the percentage of people who abide the rules. Results: The simulator showed that the improved SIRD model adequately fitted Malaysia COVID-19 data indicated by low values of root mean square error (RMSE) as compared to other existing models. The higher the percentage of people following the SOP, the lower the spread of disease. Another key point is that the later the lifting time after the lockdown, the lower the spread of disease. Conclusions: These findings highlight the importance of the society to obey the intervention measures in preventing the spread of the COVID-19 disease

Estimation of public compliance with COVID-19 prevention standard operating procedures through a mathematical model

Despite the enforcement of control plan and preventive measures, the transmission of COVID-19 is still ongoing and yet to be contained successfully. Hence, this study aimed to determine the level of compliance of the public with the standard operating procedures for COVID-19 prevention in Malaysia. A compartmental model with new formulations of timely dependent epidemiological parameter for COVID-19 outbreaks was developed. The model, consisting of ordinary differential equations, was solved by the 4th order Runge–Kutta method. The model representation is in the form of graphical user interface (GUI) built in MATLAB. The estimation of the level of compliance of the population with the control measures was done by fitting the model curve to the actual data in the GUI. The result shows that the current compliance level of the public to the control measures is at an unsatisfactory level that leads to repeated lockdown. The compliance level estimation is important to policymakers and health officials as they can infer the effectiveness of intervention strategies. Additionally, this study revealed how individual responsibility to adherence the control measures will affects the number of cases. Further action to increase public compliance to a satisfactory level is required to halt the pandemic successfully

Mathematical analysis for a system of nonlinear ordinary differential equations related to ethanol production

The fermentation process is a crucial stage in transforming substrate to ethanol. Ethanol is obtained by fermenting the substrate using microbial such as yeasts or bacteria. This process can be explained in a system of nonlinear Ordinary Differential Equations (ODEs) mathematical model. The broad understanding of the model can improve the prediction of ethanol production yield. In this paper, the stability analysis is done to investigate the stability of the proposed model and followed by the investigation of its parameter behaviour towards the model

Mathematical model for predicting the performance of photovoltaic system with delayed solar irradiance

Photovoltaic systems convert solar irradiance into electricity. Due to some factors, the amount of solar irradiance arriving at the solar photovoltaic collector at a specific location varies. The goal of this study was to develop a mathematical model for predicting the performance of a photovoltaic system, which depends on the amount of solar irradiance. A novel model for solar irradiance in the form of a delay differential equation is introduced by including the factor of delayed solar irradiance, hour angle and the sun's motion. The simulation study is carried out for the three scenarios of weather conditions: a clear day, a slightly cloudy day, and a heavily overcast day. The numerical solution is obtained by adopting the 4th-order Runge Kutta method coupled with a parameter fitting technique, the Nelder Mead algorithm, which is implemented by using MATLAB software. The data from a solar plant in Pahang, Malaysia, was used for model validation and it is found that the prediction profile for solar irradiance aligns well with the intermediate and decay phases, but deviates slightly during the growth phase. The output current and power for the solar photovoltaic panel were treated as time-dependent functions. As the solar irradiance increases, the output current and power of the solar panel will increase. The result showed that the maximum output current and output power of STP250S-20/Wd crystalline solar module decreased by 42% and 76%, respectively, during slightly cloudy and heavily overcast conditions when compared to clear days. In other words, the performance of a photovoltaic module is better on clear days compared to cloudy days and heavily overcast. These findings highlight the relationship between delayed solar irradiance and the performance of the solar photovoltaic system

Mathematical Modelling for Predicting the Performance of Photovoltaic Modul

The demand for photovoltaic (PV) system is growing rapidly driven by technological development and awareness of green environment. A photovoltaic system converts the energy of light into electricity without emission of harmful by-product. A complete PV system consists of a solar panel (which combination of few solar cells), Pulse Width Modular (PWM) and a battery. Eight photovoltaic parameters are used to characterized the quality and efficiency of a PV module i.e (i) short circuit current (ISC), (ii) open circuit voltage (VOC), (iii) Theoretical Power (PT), (iv) maximum power (PMAX), (v) voltage at PMAX (VMPP) , (vi) current at PMAX (IMPP), (vii) fill factor (FF) and (viii) efficiency (). The PV parameters of laboratory scale solar cell could be determined based on current-voltage (I-V) and power-voltage (P-V) curves which could be plotted using a combination of solar simulator and a potentiostat instruments. Two additional PV parameters i.e (i) reverse saturation current of diode (IRC) and (ii) photocurrent (IPV) have been studied intensively as input of mathematical models to simulate and determine the quality and efficiency of solar cells. However, reproduceable results and robust mathematical models are yet to be established. A mathematical model employing the IRC, IPV and diode ideality factor (a) – which received lack of focus by previous researchers; is proposed. We have validated the mathematical model by comparing the calculation I-V and P-V curves results with the specifications established by the manufacturer. We have conducted three studies based on different specification of silicon based solar module i.e (i) 300W, (ii) 265W and (iii) 250W to obtain temperature distributions and average solar irradiance at selected locations. Through a comparative analysis, the theoretical calculation results and the manufacturers’ specifications are in good agreement

Mathematical modelling for predicting the performance of photovoltaic module

The demand for photovoltaic (PV) system is growing rapidly driven by technological development and awareness of green environment. A photovoltaic system converts the energy of light into electricity without emission of harmful by-product. A complete PV system consists of a solar panel (which combination of few solar cells), Pulse Width Modular (PWM) and a battery. Eight photovoltaic parameters are used to characterized the quality and efficiency of a PV module i.e (i) short circuit current (ISC), (ii) open circuit voltage (VOC), (iii) Theoretical Power (PT), (iv) maximum power (PMAX), (v) voltage at PMAX (VMPP) , (vi) current at PMAX (IMPP), (vii) fill factor (FF) and (viii) efficiency (). The PV parameters of laboratory scale solar cell could be determined based on current-voltage (I-V) and power voltage (P-V) curves which could be plotted using a combination of solar simulator and a potentiostat instruments. Two additional PV parameters i.e (i) reverse saturation current of diode (IRC) and (ii) photocurrent (IPV) have been studied intensively as input of mathematical models to simulate and determine the quality and efficiency of solar cells. However, reproduceable results and robust mathematical models are yet to be established. A mathematical model employing the IRC, IPV and diode ideality factor (a) – which received lack of focus by previous researchers; is proposed. We have validated the mathematical model by comparing the calculation I-V and P-V curves results with the specifications established by the manufacturer. We have conducted three studies based on different specification of silicon based solar module i.e (i) 300W, (ii) 265W and (iii) 250W to obtain temperature distributions and average solar irradiance at selected locations. Through a comparative analysis, the theoretical calculation results and the manufacturers’ specifications are in good agreemen