Development of rainfall – runoff model for extreme storm events in the Bagmati River Basin, Nepal

This study is based on the Bagmati river basin that flows along with the capital city, Kathmandu which is a small and topographically steep basin. Major flood occurring in 1993 and 2002 as stated in the report of DWIDP shows that the basin is subjected to water-induced disaster in monsoon season affecting people and property. This study focuses on the development of a rainfall-runoff model for Bagmati basin in HEC-HMS using the Synthetic Unit Hydrograph (SUH) with Khokana as the outlet. The coefficients for SUH like Lag time coefficient (Ct), peak discharge coefficient (Cp), unit hydrograph widths at 50% and 75% of peak and base time were determined calibrating the Synder’s equation where Ct varies from 0.244 to 1.016 and Cp varies from 0.439 to 0.410. The rainfall-runoff model in HEC-HMS has been calibrated from daily data of 1992-2013 and validated from hourly data for July 2011, August 2012, and July 2013. Furthermore, the model has been tested to compare the discharge for various return periods with the observed ones which are in close agreement. The determination of Peak Maximum Flood (PMF) using the calculated Peak Maximum Precipitation (PMP) is also another application of the model which can be used to design various hydraulic structures. Thus the values of coefficients, Ct and Cp can be used to construct unit hydrograph for the basin. Moreover, the satisfactory performance of the model during calibration and validation proves the applicability of the model in flood forecasting and early warning.

A study on FTTH implementation and migration in Nepal

The increasing demand of high speed data results into extensive enhancement on different telecommunication technologies through wireline and wireless technologies. Optical Fiber technology is being popular for fixed broadband technologies and for backhaul network data for network convergence and media device interaction. Fiber to the home (FTTH) is gaining momentum of deployments in many countries all around the world. Passive optical network (PON) utilizes point to multipoint (P2MP) topology and is becoming suitable, cost effective, and promising solutions as compared to existing copper based telecommunication infrastructure. PON architecture is cheaper than other architectures due to dynamic bandwidth allocation and common resources that can be used by different subscribers and especially for home subscribers. This paper presents a study on the effective deployment of PON based FTTH network at Nepal by referring the deployment scenario of Nepal Telecom (NT), while this network design, deployment, and implementation provides a lesson learn for cost effective deployment of such network to other stakeholders of developing countries having similar territory and implementation challenges.

Voltage stability analysis of wind power plant integration into transmission network of Nepal

Government of Nepal has realized that wind energy could become a major source of alternative energy to solve energy crisis in the country as well as serve the purpose of energy mix. Various studies have identified several locations with potential for wind power generation in Nepal. The integration of wind power plant to the national grid, however, raises concerns regarding the power system stability. The voltage stability of the grid is a key issue, the effect on which increases with the increase in wind power penetration in the grid. This study performs voltage stability analysis due to high penetration of wind power in Integrated Nepalese Power System (INPS). Both steady state and dynamic stability study is performed using the power system simulation software DigSILENT/PowerFactory for different types of wind turbine generators.

Design and simulation of components of vacuum forming machine using household vacuum cleaner

Plastic products ranging from toothbrushes to smartphones are an inseparable commodity in daily human life and their impact cannot be underestimated. This paper aims to design and simulate the vacuum forming process using readily available materials in context of Nepal. Vacuum forming process is a thermoforming process where the heated plastic sheet derives the shape of the mold through the application of vacuum and is used to make packaging products and other household products. Simulations were done to find out the optimum distance between the plastic sheet and the heater, arrangement of the wire in the heater, load bearing capacity of the design and the flow of vacuum in the arrangement. Nichrome wire coiled as heater coil is used as the heating material and laid in a spiral path with the plastic sheet 35mm below provided the best heating results and 1800W vacuum cleaner provided the necessary pressure of 85-90kPa and velocities of 100- 115m/s while the steel posts provided adequate strength.

Analyzing effectiveness of active learning through project-based learning approach in university level ICT courses

The concept of Active Learning (AL), which has journeyed through multiple research studies over the years, is an important part of the teaching learning process at academic institutions. The present study applies active learning via project-based approaches where students engage in real life projects and solve associated complications with their research, communication, and technical skills. As a case study of effectiveness of project-based learning (PBL), especially in engineering project contexts, the present research is conducted among students studying computer science and engineering at Kathmandu University (KU), Nepal. The key findings of the study suggest that PBL assignments have helped students in their active learning processes. This paper also compares teaching and learning approaches of KU with other IT institutions of Nepal.

Evaluation of weibull parameter estimators for wind speed of Jumla, Nepal

Weibull Probability Distribution Function (PDF) is widely used across world for estimation of wind power. Weibull function is a two parameter probability distribution function. The methods employed for the evaluation of these two parameters are critical for the efficient use of Weibull PDF. In the present study, three different Weibull PDF parameter estimators have been evaluated. For this purpose, the daily averaged wind speed data of Jumla Station, Nepal for period of 10 year (2004 – 2014: 2012 excluded) is studied. The parameter estimator evaluated in this study are Method of Moments (MoM), Least Square Error Method (LSEM) and Power Density Method (PDM). It has been found that Method of Moments (MoM) is the best estimator for evaluating Weibull Parameters.

Shear and tensile bond strengths of autoclaved aerated concrete (AAC) masonry with different mortar mixtures and thicknesses

Autoclaved aerated concrete (AAC) blocks are commonly used for masonry walls. In order to understand the strength of AAC masonry, it is essential to assess the tensile and shear bond strengths of the AAC block-mortar interface for various mortar combinations. This research investigates the bond strength of AAC block mortar interface made up of a) polymer modified mortar (PMM) and b) ordinary cement sand mortar of 1:4 or 1:6 ratio with thickness of 10mm, 15mm or 20mm. A thin cement slurry coating was applied on the block surface before placing the cement sand mortar in the masonry. For all types of interface, shear bond strength of masonry was studied using a triplet test, while the tensile bond strength was determined through a cross-couplet test. Among the cement sand mortar used in this study, cement sand mortar of ratio 1:4 and thickness 15mm showed the maximum shear strength of 0.13MPa with the failure of blocks as the predominant failure while the PMM had shear bond strength of 0.12MPa with the failure of blocks as the predominant failure type. However, in case of the tensile bond strength testing, PMM showed the tensile bond strength of 0.19MPa, which was highest among all the test specimens used in this study. Considering both the tensile and shear bond strengths of the AAC masonry and based on the observed failure pattern, among all the combinations used in the experiment, either PMM or cement-sand mortar of ratio 1:4 and thickness of 15mm can be chosen for the AAC masonry.

Effects of source digital elevation models in assessment of gross runoff-river hydropower potential: A case study of West Rapti Basin, Nepal

Advancements in Geographical Information System (GIS), Remote Sensing (RS) technology, hydrologic modeling and availability of wider coverage hydrometeorological data have facilitated the use of GIS and hydrological modelling tools in studies related to hydropower potential. Digital Elevation Model (DEM) is the primary data required for these tools. They have become more accessible and many are freely available. These DEMs have different resolution and their errors vary due to their primary data acquisition techniques and processing methods. However, their effects on the hydropower potential assessment are less investigated. This study evaluates the effects of 6 freely available DEMs: ALOS 12.5 m, SRTM 90 m, SRTM 30 m, ASTER G-DEM version-3 30 m, AW3D 30 m and Cartosat-1 version-3 30 m on the Gross Run-off-River Hydropower Potential (GRHP) assessment, using GIS and hydrological modelling tools. West Rapti River (WRR) basin in Nepal was chosen for the case study. Soil and Water Tool (SWAT) hydrological model, coupled with GIS was used to discretize the WRR basin into several sub-basins/streams. Flow at the inlet and outlet of streams were estimated from the SWAT model whereas the topographic head was extracted from the DEMs. The GRHP of the streams were computed using the estimated stream flow and the topographic head for flows at 40% to 60% Probability of Exceedance (PoE). The total potential of the basin was computed by summing up the potential of all streams. The GRHP of WRR basin for flows at 40% PoE was estimated as 512 MW for ALOS 12.5 m resolution DEM, referred as a base case in this study. The GRHP estimated from the remaining DEMs showed the variation of less than 6% compared to the base case. The topographic head was found to be sensitive with respect to the DEM resolution and the highest variations were observed in the main river channels.

Assessment of the impact of COVID-19 on transportation and its inter-linked sectors of Nepal

Nepal being a landlocked country is completely dependent on the roadways and airways for means of transportation however, the railway has not been started in Nepal to date. Transportation is interlinked with mobility and due to lockdown every sector related to mobility has been affected. Consequently, the aviation sector has been worst hit as airlines were prohibited to operate. The aviation industry of Nepal has foreseen significant decadence in the mobility of passengers and cargo (international and domestic) which has affected revenue generation. Similarly, the imposed lockdown has influenced the ongoing nation's pride and the long-term investment projects which have been considered as a milestone in the infrastructural development of Nepal and those projects need to be reprogrammed and reprioritized. Moreover, the sharp decrease in import of petroleum products has decreased the revenue paid to the Indian Oil Corporation (IOC) which will help to reduce trade loss. The lockdown induced due to COVID-19 has also affected the agricultural sector as the supply chain has been disrupted due to travel restrictions. The overall Gross Domestic Product (GDP) that the transport and its inter-linked sector contribute has been reduced during lockdown than the preceding years. Identifying the paucity of research in the transportation sector of Nepal this paper is focused on the comprehensive study of the impact of the COVID-19 transportation sector along with its inter-connected areas.

Numerical modelling of the sand particle flow in pelton turbine injector

Pelton turbine is commonly employed high head impulse type turbine. Pelton turbine injector is an integrated part of the Pelton turbine machine which serves the purpose of converting entire pressure energy of water to kinetic energy and also regulates the water flowrate, with partial opening hence governing the power production. Severe erosion in Pelton turbine injector is reported from field setting research studies. Since the jet is atmospheric pressure jet, there is few chances of occurrence of cavitation hence it can be understood that impact of sand particles is the major cause of erosion. Furthermore, with turbine operating in partial flow condition, more erosion is reported in the needle of injector. For a long spear type injector, this study explores the cause of erosion by modeling the motion of the sand particle flow in steady state jet. For numerical modeling of the flow, the realizable k-epsilon model is used and for modeling the particle flow, the Discrete Phase Model (DPM) is used. Three different operating condition of the injector is considered and 77000 particles were injected to the flow domain. It is observed from the numerical simulations that the more sand particle hits the nozzle-needle surface with partial opening of the injector.