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The Tiger Panthera tigris is one of the most charismatic and well known Asian big cats. In the lowlands of Nepal, Tigers along with the Greater One-Horned Rhinoceros Rhinoceros unicornis and the Asiatic Elephant Elephas maximus serve as flagship species gathering global conservation attention. Current surveys estimate a population of 235 tigers in Nepal. Tigers in Nepal are strictly protected in five protected areas located in the lowlands and their adjoining forest areas which cover 7,668.20 km2. However, over the last century, tiger population and their distribution range drastically declined with the species heading towards extinction. The long-term survival of this charismatic species is challenging largely due to the loss and fragmentation of habitat, climate change, increasing human-wildlife interface and poaching for illegal trade of body parts. In response to this, the Government of Nepal along with conservation agencies and local communities have proceeded to execute various conservation initiatives both at national and international level. This paper tries to scrutinize the current status of tiger population, conservation efforts, and existing challenges to conserve tiger species in Nepal.

In this paper, a data-driven dynamic efficiency model is developed for efficiency evaluation and comparison of ship electric powertrain with various system configurations and load-sharing methods. Based on the proposed method, the entire powertrain efficiency is assessed from the fuel consumption to the propulsion unit and the rest of the onboard load. The efficiency model is repeated for the conventional diesel-electric and the hybrid power system with batteries. In the latter case, the efficiency of the battery system is also included in the model. Then, the analysis is extended for different power system architectures such as AC- and DC onboard power systems. As a case study, system efficiency in a cruise ship is investigated using a real operational profile. A comprehensive analysis is performed to demonstrate the loss distribution in each subsystem of a hybrid AC- and DC power system. For a fair comparison between AC and DC, the battery charge level is equalized based on fuel compensation. The case study shows that hybridizing the ship power system increases system efficiency and enhances operational flexibility for the studied use case vessel. Further, the DC hybrid power system can improve the efficiency of the whole ship powertrain thanks to the variable speed operation of engines.

Ship power and propulsion systems are being electrified for several reasons out of which emission reduction, energy efficiency improvement, and ultimately reduction in operating expense (OPEX) are the main drives. Electrification can be described as the transformation from the conventional transmission system to an all-electric transmission system linking the energy source and generation units to the power consumers. Here, a marine energy system will be established based on a so-called hybrid power system composed of three main sub-systems such as power generation, load (mainly propulsion), and energy storage systems (ESSs). In an electrified marine system, all three main elements can be converted to electric by rotatory electric machines and solid-state devices such as power converters. The main stem of the system is a power distribution system so-called switchboard which can be either AC or DC or a combination of them depending on the vessel's mission and function. The connectivity, interoperability, and seamless functioning of such hybrid systems are provided with a hierarchical control system, which includes a power and energy management system (PEMS) as well as low-level controllers, propulsion control systems, and dynamic positioning (DP). Three key enablers can be seen at the forefront of the green shift, such as electrification of the powertrains and shifting to all-electric drive; hybridization of the onboard power systems with ESS; and alternative fuels and corresponding energy conversion technologies such as fuel cells (FCs) and gas engines. The electrification has been realized based on the development of power electronics and onboard power systems among them shipboard DC grids. The recent trend of shifting from the conventional AC power system to onboard DC systems is driven by various factors including energy efficiency, control flexibility, design flexibility, and fuel flexibility facilitating the integration of emerging power sources based on alternative fuels, such as H 2 and other low-emission gaseous fuels. Here, electrification shall be distinguished from battery installation and usage. Electrification in the general form is referring to an all-electric powertrain with or without batteries. On the other hand, the hybridization of onboard power systems is increasingly implemented due to the advancements in lithium-ion battery technologies. The batteries are contributing to different aspects of the system operation such as efficiency improvement and consequently fuel and emission saving, dynamic stability improvement, and zero-emission propulsion. In addition to the efficiency improvement benefits, power smoothing of conventional engines is also a significant aspect as it reduces operational costs. Furthermore, the low or zero-emission FC power systems are shifting the paradigm in shipboard power systems. This chapter discusses watercraft systems from the perspective of power and propulsion system architectures and topologies. Furthermore, the strategies of control and load sharing are discussed mainly relevant to DC hybrid power systems. Besides, a few case studies are given to elaborate on the efficiency aspect of the onboard DC power system.

Lamichhane U, Ghimire P. 2022. Vertical distribution of soil properties and soil organic carbon in community managed forest of Siwalik Hill, Nepal. Asian J For 6: 91-96. Nepal's Community Forestry (CF) approach is globally recognized as an innovative and successful approach to forest resource management. Shorea robusta Gaertn. is the dominant tree species of Nepal's forest which covers 19.28% of the total stem volume of the country's forest area. Soil represents a significant terrestrial Carbon (C) pool and can play a significant role in mitigating global warming. Therefore, analyzing soil physicochemical properties and Soil Organic Carbon (SOC) stock is essential because they are key parameters for evaluating land use management systems. The present study was conducted in the Durga Mai Community Forest (DMCF) of Makawanpur District, Nepal, to assess the vertical distribution of soil physicochemical properties and SOC stock. Soil samples within a 1 m profile in five depth layers (0-20 cm, 21-40 cm, 41-60 cm, 61-80cm, and 81-100 cm) were collected and analyzed for Bulk Density (BD), soil texture, soil pH, soil carbon content, Total Nitrogen (TN), Available Phosphorous (AP), Available Potassium (AK) and SOC stock. Sandy loam was the dominant soil textural class reported throughout the study area. Average BD, soil pH, TN, AP, and AK in the S. robusta forest's soil in 1 m soil profile depth were found to be 1.16 ±0.07 gmcm-3, 5.78 ±0.62, 0.14 ±0.04 %, 5.94 ±1.04 kgha-1, and 104.20 ±19.66 kgha-1, respectively. The results estimated 107.57 ±3.06 tha-1 of SOC stock in 1 m soil profile, with 0.93 ±0.21% average SOC content. Further, average TN, AP, and AK were found to be decreased with an increase in soil profile depths. Similarly, soil profile depths significantly affected SOC stock and soil properties like BD, soil pH, TN, AP, and AK.

The hybridization of power systems offers the low-emission and energy-efficient marine vessels. However, it increases the complexity of the power system. Design, analysis, control, and optimization of such a sophisticated system require reliable and efficient modeling tools to cover a wide range of applications. In this work, a typical DC hybrid power system model is developed using a bond graph modeling approach. Necessary component models of varying degrees of fidelity are developed and integrated to build a system model with reasonable accuracy. The developed system model, along with the rule-based energy management system, is used to simulate the entire system and to investigate the load-sharing strategies as well as the system stability in various operating scenarios. Moreover, the simulation results are validated with experimental results conducted on a full-scale laboratory setup of the DC hybrid power system and with a ship load profile. The results show that the system model is capable of capturing the fundamental dynamics of the real system. The hybrid power system model is further used to analyze the bus voltage deviation from its nominal value. The computational efficiency presented by the system is fairly good as it can simulate faster than real-time. The developed system model can be used to build up a comprehensive simulation platform for different system analysis and control designs. © 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

Non-timber forest products (NTFPs) consist of goods of biological origin other than wood, derived from forests, other wooded land and trees outside forests. The importance of NTFPs for sustaining rural livelihoods, fostering rural poverty alleviation, enhancing biodiversity conservation, and facilitating rural economic growth is well known in Nepal. In spite of these facts, NTFPs have not received the sustained and systematic support. With the gradual rise in population, unsustainable harvesting and depletion of resources, sustainable management of NTFPs has become a challenge. Similarly, the increasing global demand of NTFPs leads to over-exploitation of these resources that further leads to dwindling and adversely affecting the biodiversity. In this context, this paper intends to explore and analyze the conservation status, prospects and challenges for efficient and sustainable management of NTFPs in the context of Nepal.

A study was carried out in Thulosirubari village of Chautara Sangachowkgadi municipality of Sindhupalchok district, Nepal to analyse the importance of TOF for immediate earthquake response and recovery. More than 80% of the households have trees in their own land with species such as Chilaune (Schima wallichii), Kutmiro (Litsea monopetala), Khote Salla (Pinus roxburghii) and Bamboo are common. Among surveyed households (134), more than 75% respondents reported that they used Schima wallichii for pillar (Khaba) to make temporary houses, whereas bamboo was used for all kind of poles (Dada/Vata/Balo) in more than 80% of temporary houses. Both Bamboo and Schima wallichii were either extracted from their own land or from neighbour's land, i.e. TOF which were easily available and collected as required. We could not draw any statistical conclusion in choice of species to construct temporary houses by wealth categories. However, we have observed that people who have sufficient and varieties of trees in own land, have selected strong and hard wood for permanent house construction whereas those who do not have choice, are limited to use any of the available tree species. People were highly aware about importance of trees to cope with disaster; however selection of species was still debatable because of limited knowledge and researches. J. Biodivers. Conserv. Bioresour. Manag. 2020, 6(1): 9-16

Community based forest management in Nepal has been widely acclaimed as the most successful approach for participatory forest management and its governance. So far, about 2,831,707 hectares of forests of Nepal have been managed under the regime of community-based forest management. During four decades of its implementation, the program has undergone a considerable shift from state dominated top-down approach to community-based participatory approach to forest management through organizational and policy reform in Nepal. The success of community-based forest management approach is described in terms of improving the supply of forest products, generating green employment, improving rural livelihood, empowering women, poor and disadvantage groups, rehabilitating degraded land and habitat and also increasing biodiversity. Yet, community-based forest management approach continues to face some organizational and policy challenges during its implementation, and this cannot be overlooked. Social exclusion, inequitable benefit sharing, elite dominance in decision making are the major challenges that are to be resolved in the years to come. Furthermore, this paper intends to illustrate the lessons learnt and the current challenges in making the decentralized forest governance more successful in the changing context.

The greater one-horned rhinoceros (Rhinoceros unicornis) is one of the iconic natural heritage of Nepal’s rich biological diversity, backed by the commitment of the Government of Nepal to conserve this rare animal for now and future generations. It is not only important for conservationists due to its ecological value, but it also holds a universal appeal for ordinary people. Over the decades, the Government of Nepal, supported by national and international conservation partner organizations and the local communities, has significantly contributed to the conservation of this iconic species. Nepal’s rhino population has increased by 45% between the year 2005 and 2015. There are now 645 rhinos in Nepal, marking an increase of 111 rhinos from the 534 recorded in the last census in 2011. These numbers reflect the success of conservation efforts for this species and are a result of improved rhino protection measures, and management of habitat. Though the population of one-horned rhinos has increased significantly over past years in the country, the protection of the rare wildlife species has remained a challenging job. Habitat loss and fragmentation, increasing encroachment of forest areas, climate change, poaching, and increasing human-wildlife conflict are major challenges for protection of this rare species. This paper discusses the current status and distribution of greater one-horned rhinoceros, and potential challenges to conserve this flagship species in Nepal.

The electrical power system in ships can be traced to the 1880s, when lightbulbs were installed on SS Columbia. Since then, electricity has been a crucial part of marine vessels. Research and development initiatives resulted in innovations including the ac motor and transformer, turboelectric power, submarines, dieselelectric propulsion, modern solidstate power electronics, the use of liquified natural gas (LNG) as fuel, and pure electric and hybrid ferries with pluggedin and wireless charging from shore.

In this paper, an efficiency and emissions evaluation framework for marine DC hybrid power systems is developed based on the physics- and data-based models of the power components. The proposed framework is tested under the operational profile of a real-case semi-submersible drill rig with all-electric propulsion and a suggetsed DC hybrid power system with batteries. The applied load profile, including propulsion, drilling, auxiliary, and hotel loads, shows high fluctuations, indicating the need for battery hybridization. In addition to the operational profile, the impact of the onboard power system configuration, sectionalized and common bus, on the emissions and efficiency has been studied. The results include the total energy efficiency of the ship powertrain from fuel to propulsion load and total CO2 emissions. For the considered vessel power system and operational profile, it is observed that the sectionalized bus configuration performs slightly better in terms of energy efficiency, and consequently fuel consumption and CO2 emissions.

Despite widespread deployment of wireless sensor networks (WSN) in remote and inapproachable locations, energy consumption/storage of WSN hindered its adoption. Similarly, the battery-powered sensor nodes are of no use once the battery is depleted. To overcome this limitation, energy harvesting is one of the key techniques. In this paper, an almost perpetual self-powered sensor node is proposed. This sensor node uses a solar panel to harvest energy while the entire energy management is accomplished by BQ25570. Similarly, a super-capacitor is used as an energy storage unit with long range radio access (LoRa) as a transceiver unit. We measured the power generated/consumed continuously for 15 days with a transmission interval of 10 minutes. The result shows that this sensor node can potentially last for more than 7 days even at a low illuminance. Considering periodic wakeup at every 10 seconds with a sleep interval of 3 sec, a timer-triggered mechanism saves approximately 595 milliwatts of energy in one day compared to a deep-sleep mechanism. Furthermore, it is found that the application of the novel idea of external timer-driven technology in sensor node reduces energy consumption and provides a much efficient power optimization mechanism compared to the deep sleep mechanism that prevailed in WSNs technology.

Co-simulation enhances the efficient simulation development even for complex systems reducing time to market and computational effort. This work aims to develop a marine hybrid power system simulator using a co-simulation approach. The subsystems are packed as Functional mock-up units (FMUs) with the standard interface called functional mock-up interface (FMI). The FMUs for major subsystems are generated from the previously developed dynamic system model. However, FMUs developed by the partners are also compatible for the implementation. These FMUs are implemented in an open simulation platform's (OSP's) software Kopl and Co-Sim App to develop a system simulator. The use of a co-simulation framework for realtime virtual testing and various model fidelity implementation is studied. The developed simulator is used for testing the functionalities and operational capabilities of the studied system. It can simulate faster than real-time, thereby enhancing its use for real-time virtual testing applications. Implementing various fidelity FMUs enhances modularity. It also increases the flexibility in an FMU selection based on the simulation objectives, accuracy, and computational effort. © 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

Biogas is an eco-friendly alternative energy source which can greatly contribute to reducing greenhouse gases as they have the possibility of reducing the need to use fossil fuels. A study was conducted at Kumroj village of Khairhani municipality, of Chitwan district of Nepal to assess the sources of energy, dependency of local people on biogas, amount of fire wood substituted by biogas and people’s perception towards biogas use and forest conservation. Stratified random sampling method was used for sampling design. Direst field observation, households questionnaire survey (n=44), key informant interview, and focus group discussions were used for data collection. This study showed that the main source of energy was firewood for cooking, preparation of animal feed, preparation of alcohol and water heating but now these days the dependency on firewood decreased after use of biogas. About 63.6% of the household were using biogas as an alternative source of energy. The need of biogas was always higher during winter while production of gas was lower in compare to summer season. According to gas users, it reduced the fuel wood consumption, improved the kitchen environment, saved time in fuel wood collection and cooking, and also reduced the health problems. The average reduction in fuel-wood consumption was 42.8% after the installation of biogas. All the respondents were agreed that condition of forest was improving. The reason behind this was the use of biogas which reduces the pressure on the fuel-wood collection and ultimately helps in forest conservation.

Nepal’s location in the centre of the Himalayan range places the country in the transitional zone between the eastern and western Himalayas. Nepal’s rich biodiversity is a reflection of this unique geographical position as well as its altitudinal and climatic variations. It is recorded that Nepal has a total of 118 types of ecosystem, 75 vegetation and 35 types of forests. Nepal has put utmost efforts to conserve its rich biodiversity resources. The conservation history began formally after promulgation of National Parks and Wildlife Conservation Act in 1973. National parks and wildlife reserves were established across the country during the 1970s. However, very soon not only some of the adversities were faced by the local people living around the parks and reserves but also the space constraint was realized for the population distribution and dynamics. By realizing the need of people’s participation in the conservation initiatives, country has tested the concept of different types of protected areas system such as national park, wildlife reserve, conservation areas, and buffer zones over the years. Taking the advantage of new progresses in conservation biology, Nepal adopted landscape level approach to biodiversity conservation and implemented such approaches in some of the key areas since 2000s. This paper discusses Nepal’s effort in implementing landscape level approach to biodiversity conservation and the lessons learned at national context.

With the increasing in frequency, intensity, and side effects of grid outages caused by weather based events, the importance of resiliency is also increased. This study presents a novel multi-objective optimization problem for improving the resilience of smart grid against natural disasters in the presence of a considerable amount of line outages occurring due to the weather conditions. The proposed model considers the management of distributed energy resources (DERs), energy storages (ESs), and dynamic topology reconfiguration of the distribution network. The main goal is based on a dynamic resilient operational planning using prediction of weather condition. The objectives in the proposed approach are defined as: to minimise operational cost of distribution network from the system operator's viewpoint, to minimise the penalty costs for energy not supplied and side effects of outages, and to maximise benefits of DER-ES owners by using flexible reconfiguration and dynamic operational planning considering weather conditions. A hybrid optimization algorithm based on genetic algorithm and -constraint method using fuzzy decision maker is employed to choose the best solution from a provided Pareto optimal set. The outcome of the Pareto solution specifies the best scheduling for DERs, ESs and switching of lines during the scheduling horizon.

This article highlights a research carried out in Gaindakot municipality of Nawalparasi district, Nepal to evaluate the opportunities and challenges of urban forestry regarding identification of existing policies and documentation of institutions involved in the field of urban forestry. Systematic random sampling method was used for the data collection during household survey. The study revealed that urban forests are governed through the all-size-fits-all forest policies, which are not favorable to urban forestry development. Plantation in the barren lands, park development, social mobilization and awareness raising are the major activities of urban forestry. The research also showed that main opportunities of urban forestry development in the study area are newly formed local government, high level willingness of local people to participate in urban forestry development, and presence of community forests around the city. On the other hand, lack of public space, narrow roads, increasing fragmentation of land, and lack of coordinated and planned efforts are major constraints to urban forestry development. This study recommends that government should take necessary steps to establish the institutional setup to facilitate the urban forestry development programmes. For this, mobilizing social organizations could be an effective tool to promote urban forestry, but a long-term plan for plantation and their management needs to be in place.

The present article primarily addresses the silvicultural system (i.e., irregular shelter wood system) in Sal forest adopted in both community and collaborative forest in Kapilbastu district of Nepal. Systematic sampling with 0.5 percent sampling intensity along with statistical tools like SPSS and MS-Excel were used for resource inventory and data analysis, respectively. The result of the study shows notable increase in seedling status during the first year (2015/16) in community forest. A decrease in sapling number during the second year (2016/17) was noticed in Tilaurakot collaborative forest at its initial level of implementation. At the same time, community forest has higher yield status with a smaller number of trees felled in Tilaurakot collaborative forest under regeneration felling. The regeneration status of species varied insignificantly (p>0.05) between the community forest and Tilaurakot collaborative forest. A recommendation is made for proper implementation of irregular shelter wood system for managing the existing degraded Sal forests of the Terai region of Nepal; however, its long-term effects on plant species diversity should also be further studied in detail.

The present article is based on the study carried out to quantify aspect wise variation in Soil Organic Carbon (SOC) stock of Churia broad leaved forest in Bhedawari Community Forest of Nawalpur district, Nepal. The total amount of SOC stock in upto 30 cm soil depth in Bhedawari Community Forest was found to be 33.91 t/ha. Aspect had made significant difference upon SOC stock with p value of 0.002 (p

Soil C sequestration through enhanced land use is a good strategy to mitigate the increasing concentration of atmospheric CO2. A study was conducted in Chhatiwan VDC of Makawanpur District to compare soil organic carbon (SOC) stocks of four main land use types such as forest, degraded forest, Khet and Bari land. Stratified random sampling method was used for collecting soil samples. Organic carbon content was determined by Walkley and Black method. Total SOC stock of different types of land followed the order: as Forest (110.0 t ha-1) > Bari (96.5 t ha-1) > Khet (86.8 t ha-1) > Degraded land (72.0 t ha-1). The SOC% declined with soil depths. The SOC% at 0–20 cm depth was highest (1.26 %) that recorded in the forest soils and lowest (0.37%) at 80- 100cm depth in degraded forest land. Thus, the SOC stock varied with land use systems and soil depths. The study suggests a need for appropriate land use strategy and sustainable soil management practices to improve SOC stock. SAARC J. Agri., 16(2): 13-23 (2018)

Soil quality is the capacity of soil to sustain biological productivity and environmental quality. Assessment of soil quality in different land use systems is essential as inappropriate land use management can degrade and deteriorate its function and stability. In this regard this study was carried out to evaluate soil quality of different land use types in Chure region of central Nepal. Soil quality index (SQI) was determined on the basis of the soil physiochemical parameters. Soil properties like soil pH, organic matter (OM), total nitrogen (TN), available potassium (AK), and available phosphorous (AP) were significantly affected by land uses types. Forest soil had the highest soil quality index (0.82) followed by bari (0.66), khet (0.64), and degraded land (0.40). Of the soil properties studied, total nitrogen and soil organic matter had the determining role in making significant impacts in the SQI among the different land uses. Hence, the results of this study can be important tool for planner, policy makers, and scientific community to frame appropriate land use management strategy.

Ghimire P, Lamichhane U. 2020. Plant species diversity and crown cover response to vegetation regeneration in community-managed forest in Makawanpur District, Nepal. Asian J For 5: 36-41. Community forestry is considered as a win-win solution for forest conservation and livelihood provision of forest-based communities. Yet, limited knowledge is available regarding the status of vegetation regeneration in community forests. The study was carried out to assess plant species diversity and crown cover response to regeneration composition in Nawalpur Saraswati (Basamadi) Community Forest of Hetauda Municipality, Makawanpur District, Nepal in November 2020 to December 2020. A stratified random sampling method with a total of 94 sample plots was applied in the study. In total, 44 species belonging to 26 families were recorded in the study site, of which 23 species were represented in tree category, 14 in shrub, and 7 in herb category. Both Shannon-Weiner and Simpson's diversity indices indicated good floral species diversity in the study area. The forest was dominated by Shorea robusta with 396 stem ha-1, followed by Terminalia bellerica 29 stem ha-1, Lagerstroemia parviflora 25 stem ha-1, and Terminalia tomentosa 21 stem ha-1, respectively. Both seedling and sapling were found in good numbers with seedlings 11,583 number ha-1and saplings were 1,896 number ha-1. Both seedling and sapling density was recorded higher in open crown coverage (seedlings=32625 number ha-1; saplings=5033 number ha-1) than in close crown coverage (seedlings=13,708 number ha-1; saplings=2,550 number ha-1). Therefore, the study concluded that crown opening facilitates the growth and development of regeneration density in Shorea robusta and its associated forests. Furthermore, the information generated could be useful to predict future trends in species composition and stand structure in order to optimize the possible forest management strategies.

With the share of high-power electronic converters, the emerging marine DC hybrid power systems have been increasingly attractive for ship designers because of their higher operational flexibility. The system efficiency analysis, one of the critical factors while embracing an emerging system, requires a detailed estimation and evaluation. Conventionally, the rated efficiency for each component is the basis for the system efficiency estimation. However, the efficiency may vary with the loading conditions in any component, directly affected by the actual load and the load-sharing strategies. In this work, dynamic efficiency models are developed for the DC hybrid power system components, which are used to estimate the overall system efficiency using a realistic load power profile and a rule-based power and energy management system (PEMS). The efficiency analysis shows that the overall power efficiency increases with optimal battery usage in a hybrid power system. Moreover, three different power-sharing control strategies are compared. The modified rule-based PEMS offers the highest efficiency, while conventional diesel generator operation offers the least efficiency for the given load profile and power system configuration.

The electrification of a ship power-train is growing at a fast pace to improve efficiency and reduce emissions. The implementation of new technologies requires test and validation using various modeling approaches. However, many of the existing models of the ship hybrid power system are too complicated and demand high computational requirements, which make them inappropriate for the real-time applications. The real-time simulation model offers the benefits of testing different control algorithms along with hardware-in-the-loop testing. The bond graph-based dynamic modeling of a ship hybrid power system with a DC grid is presented as applicable to real-time simulation. The overall system model is established using different component models with varying fidelity, so-called mixed-modeling approach. In this approach, the components and control functions are modeled with different complexity such that it can capture the necessary system dynamics while minimizing the computational time. Results show that the modeled system is capable of simulating different operating strategies of the hybrid power system. Moreover, the mixed-modeling approach has enabled the system to simulate in nearly 2.5 times faster than the real-time. © 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

International shipping contributes to a major portion of global emissions. This is expected to grow at a faster pace due to economic and population growth. According to the Third Greenhouse Gas (GHG) Study 2014 of the International Maritime Organization (IMO), the total shipping emissions during 2007-2012 were 3.1% of global CO2 emissions, 2.8% of global CO2-equivalent (CO2e) emissions, 13% of global sulfur oxide (SOX) emissions, and 15% of global nitrogen oxide (NOX) emissions. Further details are given in Table 1.

Insulated Gate Bipolar Transistors (IGBTs) are semiconductor devices used in power modules for inverters and in many other applications. The challenge however is that these devices do not last their estimated life span of about 20 years and experience different failure mechanisms. It is of interest to study the failure mechanisms to give a better understanding of how to improve reliability of these devices as well as model and accurately predict the lifetime of IGBTs. The IGBT circuitry is encapsulated in silicone gel and the presence of this silicone gel prevents visual inspection of the type of failure mechanism that was experienced by the IGBT. When using a scanning electron microscope to examine the failed module, the sample may need to be gold plated and will be placed in a vacuum. Any silicone gel remaining on the IGBT module under investigation will vaporise and coat parts of the electron microscope thus damaging the microscope. Hence there is need to be able to remove all the silicone gel from the IGBT module before proper investigation into the mechanism that caused failure can begin. The results of these experiments show a practical approach on how to remove silicone in the laboratory from IGBT modules without causing any further corrossive damage to the modules under investigation.

This paper presents monitoring of ageing in high power insulated gate bipolar transistor (IGBT) modules subjected to sinusoidal loading at nominal power level. On-state voltage for IGBT, diode, and rise in interconnection resistance are used as ageing parameters. These are measured in three different ways: calibration of power modules after 24 h of operation, offline characterization every 5 min of operation, and continuous measurement during normal converter operation. Four power modules are tested, which are cycled to different degradation levels by number of cycles, where one is tested until failure. The characterization at different stages of lifetime indicates that the rise in resistance originates from thermo-mechanical degradation of interconnects. Post-test investigations: four-point probing and micro-sectioning indicate thermo-mechanical induced degradation of the chip topside interconnects as the source for rise in resistance. Major degradations are observed in bond wires and metallization on the low side diode.

Human-Wildlife Conflict (HWC) is fast becoming a serious threat to the survival of many endangered species in the world. The lack of access to forest resources for the local community residing in the buffer zones of national parks has created conflict between the national parks, the people residing in these areas and wildlife. This study focused on to analyze the situation of human-wildlife interface of people living near the park. Direst field observation, questionnaire survey of households (n=88), on-site focal group discussions, and key informant interviews were used for data collection. The study revealed that Paddy was the primary crop accounting about 34% of the economic value of total production. Peoples in the study area perceived that crop depredation was the major problem caused by the wild animals. Among crops, the damage to Paddy was high. A total average damage of Paddy per year per household (HH) was 115.2 Kg. Economic value of average annual damage per year per HH accounted for NRs, 9211.4. About 70% respondents responded that the poor availability of food in the forest was the main problem. In case of measures to control HWC, most of them have applied different local technologies. Among them participatory method, noise making and scare row construction were the common. Most of the local people believed that, cases of the HWC was increasing and will increase in the future. Hence, promotion of income generating activities, alternative energy, and improved livelihood strategies can reduce the HWC indirectly through decreasing the dependency in forest resources. Conservation awareness program and people participation are other major aspects that should be considered to mitigate the human wildlife conflict.

Estimation of total carbon stock in any forest is very important as it provides ecological as well as economic benefits through various environmental services. The study was carried out to quantify the vegetation and soil carbon stock of natural Chirpine (Pinus roxburghii) forest of in sub-tropical region of Makawanpur district, Nepal. The inventory of estimating above and below ground biomass of forest was carried out using stratified random sampling method Forest biomass was calculated using standard allometric models. Soil samples were taken from soil profile up to 40 cm depth at the interval of 20 cm. Walkey and Black method (1934) was used for measuring soil organic carbon. Total amount of carbon stock in Pinus roxburghii forest was 213.05 t/ha with above ground carbon stock 140. 56 t/ha, below ground carbon stock 27.14 t/ha and soil organic carbon 45.35 t/ha respectively. Total carbon stock in Pinus roxburghii forest was composed of 66% for above ground, 21% by the soil and 13% by below ground. The study concluded that forest types and soil play an important role on total carbon sequestration. Hence, the goal of reducing carbon sources and increasing the carbon sink can be achieved efficiently by protecting and conserving the carbon pools in existing forests ecosystem.

In this paper, both the main effects and interaction effects of parameters on CO 2 removal efficiency were investigated. Flue gas stream data from a 500MW coal power plant has been used for the model development. The complete removal process is implemented in Aspen Plus with selected operating conditions and parameters using Monoethanolamine as solvent. The base case model is developed in Aspen Plus with specific parameter values to achieve 85% removal efficiency. The CO 2 removal efficiency variation with different parameters; such as number of stages, inlet solvent flow rate, lean loading, temperature of the flue gas and solvent stream, absorber packing height and diameter and absorber pressure are considered as the most important parameters for sensitivity analyses. The data collected from simulations were analysed using Principal Component Analysis, Principal Component Regression and Partial Least Square-regression. The correlation between variables were studied, which indicate that inlet solvent flow rate, absorber packing height and diameter, absorber pressure and temperature of the solvent stream are positively correlated with CO 2 removal efficiency whereas the lean loading and temperature of flue gas are negatively correlated with efficiency.

The conventional $RC$ -lumped thermal networks are widely used to estimate the temperature of power devices, but they lack of accuracy in addressing detailed thermal behaviors/couplings in different locations and layers of the high-power insulated gate bipolar transistor (IGBT) modules. On the other hand, a finite-element (FE)-based simulation is the other method, which is often used to analyze the steady-state thermal distribution of IGBT modules, but it is not possible to be used for a long-term analysis of load profiles of power converter, which is needed for reliability assessments and better thermal design. This paper proposes a novel 3-D $RC$ -lumped thermal network for the high-power IGBT modules. The thermal coupling effects among the chips and among the critical layers are modeled, and boundary conditions, including the cooling conditions, are also considered. It is demonstrated that the proposed thermal model enables both accurate and fast temperature estimation of high-power IGBT modules in the real loading conditions of the converter while maintaining the critical details of the thermal dynamics and thermal distribution. The proposed thermal model is verified by both the FE-based simulation and the experimental results.

A basic challenge in the insulated gate bipolar transistor (IGBT) transient simulation study is to obtain the realistic junction temperature, which demands not only accurate electrical simulations but also precise thermal impedance. This paper proposed a transient thermal model for IGBT junction temperature simulations during short circuits or overloads. The updated Cauer thermal model with varying thermal parameters is obtained by means of finite-element method (FEM) thermal simulations with temperature-dependent physical parameters. The proposed method is applied to a case study of a 1700 V/1000 A IGBT module. Furthermore, a testing setup is built up to validate the simulation results, which is composed of a IGBT baseplate temperature control unit, an infrared camera with a maximum of 3 kHz sampling frequency, and a black-painted open IGBT module.

In this paper the degradation evolution and distribution in high power IGBT module interconnects are investigated. Modules are subjected to advanced active thermal cycling by applying a sinusoidal current load switched by the device. A series of samples subjected to an increasing number of power cycles under conditions resembling real life operation are considered. Under the given load conditions the dominating failure mechanisms are bond wire lift-off and metallization reconstruction. Both failure processes are investigated using micro-sectioning approach and scanning electron microscopy combined with focused ion beam milling. The degradation evolution and distribution are analysed and discussed in relation to load conditions. It is clear that both bond wire lift-off and metallization reconstruction are complicated micro-structural processes affected by numerous stressors. Especially, the fractures causing bond wire lift-off are observed to consist of several sub-phases—delamination, intergranular, and transgranular crack propagations.

This chapter presents PC method capable to emulate closest field stresses in PMs using full-scale converter. This method could enable to optimize end-of-life investigation of PMs for laboratory test as well as for field applications. A rise in Vce, on and VFD can be used as a precursor parameter to understand aging in PMs in a real time. The presented online voltage monitoring technique is suitable for state of health monitoring as well as to generate alarming signal to make smart decision on power de-rating, operation and maintenance, removal of faulty part to prevent from catastrophic failures, etc.

The paper describes the selection of Nepalese timber for development of small wind turbine blades on the basis of locally based low cost timbers, along with the selection of coatings to protect the timber from weathering. The selection criterion of timber includes timber mechanical properties, weathering effect on coatings, price, growth and availability of the timber. Mechanical properties such as Young's modulus of elasticity, breaking strength, breaking strain and Brinell's hardness of selected Nepalese timbers are presented. The effects of weathering on timbers without coating, and with different coatings, are analysed on the basis of the change in weight of the timber due to the effect of humidity and rainfall over a period of nineteen months. Degradation of different coatings of timber are compared.

This paper describes the research and development activities carried out by Kathmandu Alternative power and Energy Group (KAPEG) in promotion of wind energy technology in Nepal. Based on the published report, a brief review of wind energy practices in Nepal is presented. The future opportunities in wind energy in Nepal are discussed. KAPEG's completed and ongoing activities in promotion of small scale wind energy are presented. KAPEG has been receiving significant technical and financial assistance from international partners to develop the expertise which is also discussed. Finally, based on the KAPEG experience some of the future works are recommended for the development of wind energy technology in Nepal.

This paper presents on-state collector-emitter voltage (υ ce, on )-load current (I c ) method to monitor chip temperature on power insulated gate bipolar transistor (IGBT) modules in converter operation. The measurement method is also evaluated using infrared (IR) thermography. Temperature dependencies of υ ce, on at load current is measured and temperature dependency calibration factor is formulated. This method needs a correction to compensate a deviation in the interconnection resistance from homogeneous temperature field in calibration to non-homogeneous field in loading. The correction parameter is obtained from a static calibration and the method is proposed in the paper. Ageing compensation in estimating the temperature is illustrated. The correction parameter is also analysed in finite element model and also investigated experimentally superimposing heat by conducting device for a longer time in the calibration.

Power density is a key performance factor in order to reduce the cost and size of a power converter. Because of the unknown junction temperature, today’s design margins are relatively high to ensure safe and a reliable operation. In this paper, the on-state voltage drop is measured online for all insulated gate bipolar transistors (IGBTs) in the inverter, using advanced gate driver. The die temperature is estimated and monitored on each device during power converter operation. Based on the monitored temperature in real time, the maximum power capability is detected. The output power is increased until a safe operating temperature of power modules. This enable a power density is increased by 11.16 kW/litre to 19.13 kW/litre in a low voltage power stack which is typically used in wind power converters. Experiment results are shown for safe operation of converter at around 1.2 MW, which is built in a standardsize for the 600 - 700 kW. Furthermore, the 1700 V, 1000 A power module is replaced with a 1400 A module to increase the load current.