Journal of Science and Engineering

Skew Lomax Distribution, Parameter Estimation, Its Properties, and Applications

Arjun Kumar Gaire — Sun, 31 Dec 2023 00:00:00 +0000

In this paper, a three-parameter distribution called the ‘Skew-Lomax’ distribution is proposed, which is the special case of the Azzalini distribution to generalize the Lomax distribution. The Lomax distribution is also called Pareto type II distribution, which is a heavy-tailed continuous probability distribution for a non-negative random variable. The statistical properties of the proposed Skew-Lomax distribution, including mean, variance, moments about the origin, cumulative distribution function, hazard rate function, quantile function, and the random number generation have been derived. Also, the method of maximum likelihood and the method of moment to estimate the parameters of this distribution have been proposed. Three real data sets have been used to illustrate the usefulness, flexibility, and application of the proposed distribution. The coefficient of determination, chi-square test statistics, and the sum of the square of error depicts that the proposed model is more flexible than the Lomax distribution.

Computational Complexity Comparison between DC-biased Optical OFDM and Asymmetrically Clipped Optical OFDM in Visible Light Communication

Sunil Kumar Shrestha — Sun, 31 Dec 2023 00:00:00 +0000

Optical wireless systems are constrained to send real and positive values to the optical transmitter as only intensity of a signal is used to carry information. Therefore, conventional OFDM cannot be directly applied in optical systems. To combat multipath distortion, several modified OFDM systems have been studied, such as DC-biased optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM). In order to transmit real signal in optical environments, there is a Hermitian symmetric constraint with Discrete Fourier transform (DFT). This paper compares transceiver complexity of ACO-OFDM with that of DCO-OFDM which is used in Visible Light Communication (VLC), and it is found that for the same number of subcarriers, computational complexity is higher in ACO-OFDM.

Site Specific Non-Linear Ground Response Analysis and Soil Structure Interaction Study of Newly Constructed Dharahara Tower

Santosh Katuwal, Subeg Man Bijukchhen, Chandra Kiran Kawan, Anjali Shilpakar — Sun, 31 Dec 2023 00:00:00 +0000

This study investigates the seismic performance of the recently reconstructed Dharahara tower, a historically significant monument in Nepal that has experienced damage in past earthquakes and was completely destroyed in the recent Gorkha earthquake. Ground Response Analysis (GRA) and Soil-Structure Interaction (SSI) investigations are conducted to assess its structural behavior. GRA includes free field and structure-influenced analyses, with subsequent comparative assessment. Additionally, 3D non-linear finite element analysis is employed to derive equivalent spring constants representing soil and foundation characteristics, which are incorporated into the SSI analysis. These computed spring constants are used to model support conditions, allowing for an evaluation of the super-structural response. The study also employs non-linear dynamic analysis to compare structural responses between fix-based and spring-based models. The results indicate that the presence of the structure significantly influences surface wave motion amplification in GRA, resulting in peak ground accelerations (PGAs) that exhibit de-amplification in the free field and amplification in the presence of the structure. Furthermore, the introduction of an equivalent spring system in the soil-structure model changes the system's vibration period and damping characteristics, leading to enhanced dynamic response compared to the fixed-base model.

Factors Determining the Adoption of Induction Stove for Household Cooking in Bhaktapur

Yogesh Bajracharya, Pujan Adhikari, Bishnu Prasad Sharma — Sun, 31 Dec 2023 00:00:00 +0000

The current global warming trend is unequivocally the result of human activities and is proceeding at an unprecedented rate over the millennia. About 6.7 percent of global greenhouse gas emissions are caused by household cooking. It is essential to expand the use of clean fuels and technologies to reduce household emissions. Most households in urban areas use LPG for cooking purposes along with a gradual introduction of electric induction stoves. The main objective of this paper is to identify the factors determining the choice of induction stoves for household cooking. Primary data were collected from 300 households of Bhaktapur and Madhyapur Thimi Municipalities in March, 2021. Binomial Logit regression was performed to examine the determinant of induction stove adoption by household. LPG is the primary source of cooking for household. Sixty seven percent of households use electricity partially for cooking purposes. Forty five percent of total households use an electric rice cooker and 27 percent use an induction stove. Twenty six percent of households do not know about induction stoves. The family's education level, particularly the cooking member, is the primary determinant of adopting an induction stove. The probability of adoption of induction stoves increases with an increase in income. Families living in their own houses are more likely to use induction stoves than those living in rented houses.

Distribution Network Reconfiguration Using Genetic Algorithm for Loss Reduction: A Case Study of Katunje Feeder, Bhaktapur

Rakesh Gwachha, Tanus Bikram Malla, Yogesh Bhattarai, Rupesh Gautam — Sun, 31 Dec 2023 00:00:00 +0000

The power distribution system has difficulties with regard to power loss and unacceptable voltage drops as a result of the rapidly expanding power system network, rising electrical energy consumption, and longer distances of power distribution. A typical strategy to address the issues with the distribution system is to perform distribution system reconfiguration. The study focuses on distribution feeder reconfiguration of the Katunje Feeder of Bhaktapur, Nepal where optimization problem is formulated to minimize the system active power loss and investment cost of the system. Genetic algorithm is employed in a co-simulation framework to solve the optimization problem where states of 26 different tie switches are to be altered to achieve the desired optimum results. Two cases are formulated: in case I active power loss is assigned more weight than investment cost whereas, in case II equal weights are assigned for active power loss and investment cost. The results showed the reduction in active power loss and investment cost for both the cases. Case I resulted in more active power loss reduction compared to case II, and case II resulted in more investment cost reduction compared to case I. From this, decision makers can obtain insights in adopting one of the cases for distribution feeder reconfiguration based on technical consideration (active power loss reduction) or economic consideration (investment cost reduction).

Landslide Susceptibility Analysis of Jugal Rural Municipality, Sindhupalchok

Prateek Pradhan, Bhim Kumar Dahal — Sun, 31 Dec 2023 00:00:00 +0000

Hilly and mountainous areas of Nepal, with challenging terrain, young geology, and heavy monsoon rainfall, are susceptible to landslides and slope instability. To analyze and prepare landslide susceptibility maps, this study selects a typical hilly area, the Jugal Rural Municipality in Sindhupalchok district. Twelve factors contributing to landslides were considered, including slope, aspect, elevation, geology, land use, proximity to roads and drainage, plan curvature, profile curvature, NDVI (Normalized Difference Vegetation Index), soil type and rainfall. Moreover, 286 landslides were identified using high-resolution satellite imagery and field verification as the landslide inventory. These landslides were then randomly divided into two sets: 70% for training and 30\% for validation. Bivariate statistical analysis was performed using factor maps and the landslide inventory map. Notably, the analysis revealed a Prediction Rate (PR) of 9.35 for 'Land use', the highest among all factors considered. Since land use is a dynamic factor, we recommend conducting an analysis of land use changes and their impact on landslide susceptibility. Such an assessment would be invaluable during the planning and execution phases of development projects in Nepal's disaster-prone regions.