bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental study of sediment erosion in Francis runner using a non-recirculating test rig
Authors: Poudel Ravi , Chitrakar Sailesh , Chhantyal Ashish , Qian Zhongdong , Guo Zhiwei , Thapa Bhola 
Published: August 2024

Abstract
The problem of sediment erosion in hydraulic turbines has posed challenges in design, operation and maintenance of hydraulic machinery. A study was conducted with a 2 kW model Francis runner for investigating the erosion prone locations. The runner and guide vanes were coated with four different coats of colour (red, yellow, green, and blue). The system was then operated in sediment-laden condition with an average concentration of sediment particles of about 24000 ppm. The runner was operated in sediment-laden conditions for 36 hours and the observations were made after each 4 hours of operation. With increasing hours of operation, the colour coating of the runner was eroded at specific locations and a pattern was revealed showing the areas affected by erosion. The erosion was mostly observed at the trailing edge of the pressure side and the junction of the suction side of the blade and hub. Erosion on the hub was observed towards the leading edge of the runner in the area close to the suction side and the region near the trailing edge of blade. Similarly, the guide vanes were eroded at the pressure side of the leading edge and the trailing edge of the suction side. The causes of erosion were identified as high velocity and acceleration of sediment particles, inter-blade vortex, and vortex due to leakage flow.
Comparative Analysis of wear on Hard and Soft Coated Francis Runners: A Case study of Kali Gandaki ‘A’ Hydro Power Station
Authors: Poudyal Atmesh , Prasad Neopane Hari , Chitrakar Sailesh 
Published: August 2024

Abstract
Surface coating on Turbine components is a regular practice in hydro power plants to tackle with wear. The Kali Gandaki ‘A’ hydro power station of Nepal having 3x48 MW Francis Turbine units made of CN 13/4 material has been regularly coating its Runners entirely using Tungsten Carbide based alloy through HP-HVOF hard coating process. In 2021 for the first time one of the Runners was partially coated around the blades using elastomeric semi-soft coating material manually via brush application, while the remaining portion of the Runner was hard coated. This study was conducted to compare the wear on the hard and soft coated runners after a similar period of operation under similar circumstances. Both the Runners were found to be heavily worn out at the upper and lower wearing rings, suction side of all blade inlets at the shroud and all blade outlets. The soft coated runner was found to have more erosion and cavitation wear than the hard coated runner. A unique canal-type cavity was found on the hub side wearing ring of the soft coated runner but no such pattern was seen on the hard coated Runner. The sections of the soft coated Runner where the coating was still intact had the parent material fully protected, but the sections with coating completely washed away were found to have deeper and wider cavities showing that the parent material had significantly washed away. The major reason behind the soft coated Runner being more worn out could be the manual application of coating material using hand brush which could have resulted in blade profile being distorted due to which the Runner efficiency might have reduced and thus higher erosion and cavitation occurred. This study could be useful to assess the applicability as well as the benefits and drawbacks of hard and soft coating on Francis Runner.
Numerical Investigation of Effects of Ripple Type Needle Erosion on Pressure Inside a Pelton Nozzle
Authors: Satyal Sajan , Abregu Jim , Bhattarai Bikram Singh , Nascimben Francesco , Chitrakar Sailesh , Neopane Hari Prasad , Gunnar Dahlhaug Ole 
Published: August 2024

Abstract
Pelton turbines, a commonly used impulse turbine for hydroelectric generation which converts the potential energy of the water into kinetic energy through a needle structure within the nozzle system. However, the exposure of the Pelton turbine components such as needle, seat ring, buckets to the sediment laden water can erode these components. The erosion on the needle can also lead to the efficiency degradation. This study aims to investigate the effect of needle erosion on the pressure dynamics within the Pelton nozzle system. For the study purpose, the nozzle system from Pelton rig at the Waterpower Laboratory, NTNU is used and a general erosion pattern is developed through literature and field information. The research focuses on analysing the difference in pressure distribution between the normal and eroded needles under different opening conditions, with the objective of understanding how erosion affects the nozzle performance. Single-phase 3-D simulations are performed with an unstructured ANSYS mesh and the CFX solver. This study examines the static pressure at the inner surface of the nozzle casing wall. The results show that for a constant head at the inlet boundary condition, the static pressure with eroded needles was significantly lower than that with normal needles. The pressure difference was around 1.88 kPa for a 60% nozzle opening and around 3.57 kPa for a 40% nozzle opening. The reduction in pressure is due to the increased area in the needle orifice and nozzle outlet caused by erosion, which is more pronounced at lower openings.
The findings reveal a direct correlation between needle erosion and alterations in pressure distribution, highlighting the necessity for vigilant monitoring and timely maintenance. The study provides valuable insights into optimizing turbine performance in sediment-laden water conditions and underscores the importance of addressing needle erosion to maintain efficiency.
Evaluation of the jet distortion by sediment erosion in the needle in the Pelton turbines
Authors: Abregu Jim , Scheuer Jonas , Satyal Sajan , Solemslie Bjørn W. , Dahlhaug Ole G. 
Published: August 2024

Abstract
In order to succeed in the transition to a more renewable energy sector, the hydropower industry must overcome multiple challenges in the coming decades, including the need for faster and reversible turbines to support emerging renewable energy sources. In addition, the location of new projects in tropical and semi-tropical areas poses unique considerations, as does the increase in sediment.
Evaluating sediment erosion in turbines is a critical challenge, which may partly be addressed by analyzing the behavior of water jets from eroded nozzles in Pelton turbines. This paper presents an evaluation of the quality of the jet under various hydraulic conditions, focusing on needle erosion. The study is part of a research project conducted in the Waterpower Laboratory at NTNU, focusing on Pelton turbines.
Furthermore, this paper investigates erosion patterns caused by sediments on the needle and explores the impact on jet performance. Through high-speed visualization and image processing, the behavior of a jet from the needle tip to a representative distance downstream has been investigated. The investigation revealed discernible differences between jets with eroded and uneroded needles in size and edge variation.
Numerical Investigation on Hydraulic Performance of Reversible Pump Turbines with Various Wrap Angles in Turbine Mode of Operation
Authors: Bhurtel Mausam , Bijukchhe Pawan Lal , Pokharel Nischal , Thapa Biraj Singh 
Published: August 2024

Abstract
Reversible Pump Turbines (RPTs) are radial turbines, used in Pumped Storage Hydropower (PHS) plants. They have two modes of operation: generating and pumping. Despite of their uniqueness and importance, RPTs have typical range of operation at both modes and are prone to undesirable instabilities. The shape of the geometry plays a crucial role on reducing these characteristics and even the minor changes to the geometry can have a significant impact on its performance. In this paper, the effect of blade wrap angles on the hydraulic performance of runner was studied in an attempt to mitigate instabilities at turbine mode of operation. For that, two dimensionally similar RPT runners were designed using CFTurbo software by only varying wrap angle. The wrap angle considered for the runners are 150° and 180°. Steady state simulation was done in ANSYS-CFX for both the designs under same boundary conditions. It was found that the hydrodynamic performance of the runner gradually decreases in both cases when the operating condition deviates from normal operating range, causing flow instabilities within the runner. The study also found that varying blade wrap angles had no significant impact on the reduction of instabilities on RPTs, however it is an important parameter that comes into play while designing turbines at different head and flow conditions.
A numerical study on the effect of spanwise installation of vortex generators on Francis runner blades
Authors: Kayastha Atmaram , Neopane Hari Prasad , Dahlhaug Ole Gunnar 
Published: August 2024

Abstract
Hydro turbine operation far off from its best efficiency point introduces vortices and swirl that detaches flow from the blade surface. This break-off of flow accounts to loss in hydrodynamic lift accompanied by pressure fluctuations and vibration that leads to poor performance and mechanical failure of the turbine blades. Vortex generators (VGs) are efficient passive devices deployed to enhance aerodynamic lift of wind turbine blades and aircraft wings and can improve hydrodynamic lift on turbine runner blades as well. This study aims to investigate on the possibility of installation of VGs on the runner blade at leading edge, midspan and trailing edge of the runner blade. The study is carried out on a model Francis turbine developed at Waterpower Laboratory, NTNU. The numerical study is mainly focused on improving performance of the turbine at low speed as well as at the best efficiency speed. The operating head selected for the study is 11.94 m and the speed of the turbine is varied from 233 rpm to 433 rpm at an increment of 25 rpm. The turbine is simulated at different positions of guide vanes and hydraulic performance is calculated and the results of the analysis are compared with reference case without VGs. The results at deep-part load show major improvement in runner efficiency with increment in values up to 4%. The core purpose of the research is to develop effective techniques to operate traditional turbine runner at variable speed with cost-efficient minimal modifications in the geometry of the runner blades.
Site-Specific Seismic Hazard Analysis for Shallow Tunnel in Nepal
Authors: Thapa Umesh Jung , Thapa Pradip , Paudel Satish , Timalsina Shiva Prasad , Khadka Shyam Sundar 
Published: August 2024

Abstract
Several seismic codes are implemented for the design and construction of superstructures in Nepal but there is no seismic guideline for shallow tunnels which are often constructed using conventional engineering approaches. The uniform hazard spectrum was obtained after performing a Probabilistic Seismic Hazard Analysis at Dhulikhel and the target spectrum was estimated by comparing it with the spectrum recommended by the seismic code of Nepal Building Code NBC 105:2020 and Indian standard IS 1893:2016. The average response spectrum from ten recorded earthquake ground motions was selected from a peer ground motion database with the known shear wave velocity obtained from geophysical survey. The comparative analysis revealed that the design spectra for identical soil classes, as determined by this study are slightly higher than those prescribed by the present seismic code provisions. This finding emphasizes the necessity for developing more specific guidelines tailored to the design of shallow tunnels in Nepal to ensure their structural resilience in the event of an earthquake.
Introduction
Authors: Ungemah Joe 
Published: August 2024

Abstract
This chapter introduces the concept of being a fanatic and the historical connotations that the term elicits. Whereas common definitions of fanaticism emphasize strangeness or extreme behavior, the book is positioned to embrace fanaticism for all the benefits it provides while acknowledging that passion can sometimes go too deep and interfere with healthy living. The introduction outlines the structure and content of the chapters with an overview of how personality and context come together to influence whether an individual will find a passion area and stick with it. Positive and problematic versions of fanaticism are introduced, in addition to the social, physical, emotive, and cognitive psychological domains that provide the backbone to the book’s primary model. A set of motivations are proposed, which are said to combine in unique patterns to drive and maintain fanatic behavior. If harnessed, these motivations provide opportunities for human connection and the potential to heighten fanatic experiences.
Galactic Connections
Authors: Ungemah Joe 
Published: August 2024

Abstract
This chapter enters the world of science fiction fanatics and the conventions they attend. Drawn together by a common interests in the genre, they make connections that go beyond art and movies, sometimes finding hope in humankind and more often joy in sharing fantastic worlds with like-minded people. Science fiction is shown to build bridges to existing and new relationships alike, with the benefits extending to psychological well-being, helping fanatics deal with loss or reinvent healthier ways of living. This is put in contrast to other types of fandom, notably football hooliganism, where identification with a team can spill into physical confrontation. Science fiction and fantasy can also be part of therapy itself, providing a mechanism for therapists to relate better to their clients, a metaphor for life’s troubles, or ways for clients to try out new behaviors in a safe environment.
Lemons to Lemonade
Authors: Ungemah Joe 
Published: August 2024

Abstract
This chapter considers how individuals cope with hardship and tragedy through activism and joining groups that drive social change. Using a negative life event as the motivation to do something meaningful produces a different type of fanaticism, one that extends beyond the individual to make other lives better. Individuals who once relied on the support of others transform into the providers of support, often to people outside their immediate social universe. They show a level of empathy that is difficult to replicate without the lived experience of trauma and loss. This journey is difficult and not guaranteed, but those who successfully navigate grief rediscover life’s purpose and redefine their personal identities. The stories captured here demonstrate that trauma or tragedy may never be forgotten, but peace and balance can be restored through a deep connection with others.
Virtual Escapism
Authors: Ungemah Joe 
Published: August 2024

Abstract
This chapter dives into the pursuit of escapism, where gamers leave the physical world to reinvent their personal identity and make fresh social connections. The virtual world provides a blank canvas for gamers to question who they are and to behave in ways that people in the real world might consider out of character. Yet if taken too far, gamers have the potential to prioritize the virtual world and lose their anchor to real life, a symptom of addiction similar to other forms of fanaticism. A set of entrepreneurs, who are also early adopters of augmented and virtual reality, provide an alternative perspective by advocating for the benefits of the technology and offer everything from therapies for Alzheimer’s patients and pain reduction to commercial applications in architecture. Fanatics of virtual reality look to break the boundaries of the physical world, reinventing themselves and their environments along the way, but sometimes place real-world relationships at risk.
Compulsive Perfection
Authors: Ungemah Joe 
Published: August 2024

Abstract
This chapter dives into the world of innovation and entrepreneurialism, to uncover the motivation behind creating something new and sharing it with the world. Faced with financial obstacles, public embarrassment, and potential failure, fanatics of innovation and creativity are resilient in their pursuit to create something amazing. Their internal need for achievement drives their behavior towards a positive version of perfection, while their low fear of failure keeps their self-confidence running high. Like other forms of fanaticism, much of the innovator’s activity is solarity, achieving a state of flow when the creativity is running strong. This is very different for individuals demonstrating negative forms of perfectionism, which is rooted in perceived high social expectations, or those suffering from obsessive-compulsive disorder, where driving toward perfection acts as a bully and sucks enjoyment away. Through exposure therapy, the bully is contained and balance restored to allow individuals to pursue their passions.
Happiness on Sale
Authors: Ungemah Joe 
Published: August 2024

Abstract
This chapter investigates how indulgent treats can either maintain or repair a positive mood. Self gifts, like chocolate or soda, work to balance out negativity and restore individuals to homeostasis, whether bought deliberately or as a form of impulse buying. These effects work best if the consumer is fully in the present moment and mindful of the enjoyment that they receiving. If used in excess, a dependency on treats can lead to both physical and mental health issues, as consumers forget how to regulate themselves in the absence of a mechanism to boost mood. Longer-term happiness is best addressed through psychological techniques that focus on awareness of root causes and behavior change, such as visioning or acceptance and commitment therapy. Fanaticism of indulgent treats is not localized to the consumption of the treat, but rather extends to those who have devoted their professional lives to creating or selling treats for the happiness it brings to others. These individuals are fanatics of happiness and the experience of watching others indulge to forget life’s worries.
Subordinate–Superior Interactions and the Economy of the Passions
Authors: Taylor Hillary 
Published: August 2024

Abstract
This chapter examines contemporary theorizations of the passions in conjunction with other sources. Interactions between socially unequal parties were framed as exchanges in pleasure or enjoyment. The pleasure allegedly experienced by each party varied in relation to their position. This way of conceptualizing social relations served multiple functions. It collectively provided authorities with comforting narratives that they could tell themselves about how their authority operated. It enabled the ‘better’ sort to articulate a positive sense of identity vis-à-vis the gentry—the social group that had traditionally been regarded as playing the most important role in the maintenance of the social order. It euphemized and concealed the unease that labouring and poor people could feel when they encountered their ‘betters’, as well as the role that such encounters might play in the naturalization of their subordination.
The Costs of Inarticulacy
Authors: Taylor Hillary 
Published: August 2024

Abstract
This chapter examines ‘inarticulacy’ as a social and an ideological phenomenon in early modern England. It considers contemporary attitudes towards stammering, disfluent, and ‘incoherent’ speech, how these attitudes were shaped by speakers’ social position, and the experiences of ‘inarticulate’ individuals who occupied different places in the hierarchy. The costs of inarticulacy varied in relation to a given speaker’s social position. For members of the gentry and ‘better’ sort, disfluent speech could not only compromise their ability to project their authority in the expected manner but also enable their inferiors to resist demands that were made of them. The costs of inarticulacy were different for poor and labouring people. When they spoke disfluently in power-laden situations, they unwittingly justified their subordination by confirming commonplace assumptions about the relationship between social inferiority, language, and cognitive ability.
Conclusion
Authors: Taylor Hillary 
Published: August 2024

Abstract
The conclusion reprises the book’s main arguments about the ways in which language reflected, reproduced, and naturalized inequality in early modern England. It extends the discussion by demonstrating that these points were not altogether lost on contemporaries through an examination of some mid-seventeenth century radicals’ commentaries on the relationship between language, socio-economic inequality, and existing structures of authority. In their estimation, the creation of a more just social order would require—among other things—a restructuring of existing modes of social interaction; in practice, their efforts met with limited success. It concludes by considering the implications that the analyses advanced over the course of the book might have for our understanding of the social history of politics in early modern England.
Electrical Properties of Materials, 11th Edition
Authors: Solymar Laszlo , Walsh Donald , Syms Richard 
Published: August 2024

Abstract
A classic text in the field, providing a readable and accessible guide for students of electrical and electronic engineering.
The 11th edition includes many new diagrams and photographs illustrating fundamental material properties, measurement systems, and new applications.
Ideal for undergraduates, the book is also an invaluable reference for graduate students and others wishing to explore this rapidly expanding field
The Electron as a Particle
Authors: Solymar Laszlo , Walsh Donald , Syms Richard 
Published: August 2024

Abstract
Describes a number of electrical aspects of material behaviour best understood using a particle rather than a wave model of an electron, including electrical conductivity, the Hall effect, electromagnetic waves in solids, transmission and reflection at boundaries between media with different properties, electromagnetic waves in the presence of a magnetic field, plasma waves, surface plasmons at boundaries between metals and dielectrics, thermal noise (otherwise known as Johnson noise) and heat flow.
The hydrogen atom and the periodic table
Authors: Solymar Laszlo , Walsh Donald , Syms Richard 
Published: August 2024

Abstract
Considers solutions of the Schrödinger wave equation for a single electron confined in the potential distribution associated with the hydrogen atom. Finds spherically-symmetric solutions, together with their associated energy levels and probability distributions. Introduces the idea of quantum numbers to describe more general non-symmetric states. Considers the additional effect of electron spin, and introduces Pauli’s exclusion principle as the limit to the number of electrons in any given state. Discusses how the periodic table of the elements can follow from solutions of the Schrödinger equation for atoms with larger numbers of electrons.
The free electron theory of metals
Authors: Solymar Laszlo , Walsh Donald , Syms Richard 
Published: August 2024

Abstract
Introduces the idea of free electrons in a metal as solutions of the Schrödinger equation for the potential distribution defining a large, three-dimensional volume, finds the associated density of states, shows that the probability of occupation of those states is given by the Fermi-Dirac distribution function, and uses these ideas to define the specific heat of electrons. Introduces the work function as the energy needed for an electron to escape from a metal, and shows how a supply of thermal energy can increase emission in the heated tungsten filament. Shows further how strong electric fields can reshape the confining potential barrier (the Schottky effect), allowing escape by tunneling and enabling the field emission microscope. Shows how the energy may alternatively be provided by photons in the photoelectric effect. Finally, considers a related application for tungsten filament, the tungsten-halogen lamp, and electron behaviour at a junction between two metals.