bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Analysis of Power Converter Topologies in Fuel Cell Applications.
Authors: Shrestha A , Chaudhary C , Yadav N K , Thapa B S 
Published: December 2023

Abstract
The global transition from carbon-based fuel to cleaner energy sources has brought an application of hydrogen as fuel in multiple hybrid applications from backup power to onboard power sources, especially in the automobile industry. The application in the fuel cell hybrid system brings the integration of fuel cells with Lithium-Ion batteries and ultracapacitors. The efficient and reliable operation of the vehicle drivetrain highly depends on the power control mechanisms integrated with the system. Power converters play a significant role in converting the DC to DC or AC and AC to DC which maintains the power supply driving the hybrid power transmission system and other vehicle auxiliary loads. Fuel cell vehicles require high efficiency of the converters to optimize fuel consumption in various operating conditions. The paper introduces various topologies of Power electronic converters used in hybrid applications along with their pros and cons in various switching techniques adopted. The different power electronic converters are modeled in MATLAB-SIMULINK and comparative analysis has been performed to improve the efficiency and reliability of the system.
Challenges and prospects of steel production using green hydrogen in Nepal
Authors: Mahat Chiranjeevi , Jibran Jahir Ahamad , Sharma Nischal , Thapa Bhola 
Published: December 2023

Abstract
Steel is one of the most significant commodities for global development thus the production of steel cannot be condensed, however, steel making process can be transformed with a low-carbon fuel. The steel industry is a highly energy-intensive sector that alone is responsible for utilizing 8 % of global energy demand and accounts for 9% of global greenhouse gas emissions. The Intergovernmental Panel on Climate Change (IPCC), United Nations Sustainable development goals-2030 (SDG), United Nations Framework Convention on Climate Change, and the Paris agreement have directed to take necessary measures to confine global temperature rise to below 2°C till 2050. Green hydrogen is the most prominent energy carrier and with the help of renewable hydroelectricity to produce it, Nepal has the potential to be the cheapest producer and exporter of green hydrogen. Billet worth 865 USD was imported in 2020 to fulfil the annual steel demand of 1.2-1.4 million tons. Nepal has explored iron reserves (hematite) with a total Fe recovery potential of 70% which is sufficient to fulfil the steel demand of 50-100 years at Dhaubadi, Nawalparasi, and has prevailing iron reserves in other parts of Nepal. The history of steel production in Nepal has been studied and the reasons for the discontinuation have been analyzed. Secondary data from the literature and archival data have been used as methods to conduct the research. The status of energy demand and supply in Nepal and the energy management issues in Nepal during the wet season have been identified as opportunities to establish green hydrogen production in Nepal. The urgency to establish the steel industry and the need for compliance with climate change agreements are the motivation for the adoption of a green steel production process for Nepal. This paper reviews the current status and opportunities of the steel industry in Nepal using green hydrogen and proposes the future prospects and challenges that come along.
An Assessment of Proton Exchange Membrane Water Electrolyzers
Authors: Rajbhandari A , Thapa B S 
Published: December 2023

Abstract
As the world is facing the effects of global warming and climate change, it has become an enormous priority to tackle those impacts. Since the world is heavily dependent on fossil fuels which are the major contributor of carbon, trying to find an alternative for a carbon-free future without disrupting the energy balance is a treacherous task. Green Hydrogen produced via electrolysis from renewable electricity can be a game changer in the future. Electrolysis is done by a device called electrolyzer and Proton Exchange Membrane Water Electrolyzers (PEMWE) have been touted as the most prevalent. In this review paper, the very basics of PEMWE will be discussed and then delve into the key components of PEMWE where materials, a few research, challenges, and then future suggestions will be delivered.
Steady-state modelling of PEM fuel cell for evaluation of performance.
Authors: KC S , Dhakal U , Karki P , Thakuri D 
Published: December 2023

Abstract
The influence of operating variables like temperature, pressure, humidity etc. needs to be reduced to optimize the performance of proton exchange membrane fuel cells (PEMFCs). A model that can accurately simulate the real operating conditions of a fuel cell can be used to optimize its performance. This paper develops and simulates a mathematical model for PEMFC in steady-state operating conditions. A steady state model is built in MATLAB-Simulink environment. The effects of different operating variables on the performance of the PEMFC have been studied. The parameters include operating temperature and reactant flow pressure. The results in the form of polarization curve, efficiency, power and current density have been analysed to compare the fuel cell behaviours. The results show good conformity with other existing models.
The Attractors of Super Iterated Function Systems on Fractal Space
Authors: Jiang Nan , Ma Nana , Li Wei , Li Fei 
Published: December 2023

Abstract
Fractal geometry is a new branch of mathematics, which has a very wide and important application in everyday life. Iterated function systems (abbrev: IFS ) play an important role in constructing fractal set, which is a critical method in fractal geometry. The attractor is also an important concept of fractal geometry, which is obtained by an iterated function systems or a super iterated function systems (abbrev: SIFS). The SIFS is a significant generalization of the IFS by taking the number of functions of the IFS from finity to infinity. This study extend IFS to SIFS through uniform convergence. Then, some important properties similar to IFS are obtained, particularly the property of the attractors. Finally, The relationship among the attractors between SIFS and IFS is obtained, denoted by

lim

n
→
∞

A
n

=
A

.
Identification and Number Prediction of Natural Gas Heating Users in a Company in Chengdu
Authors: Ding Xianfeng , Qin Yiyu 
Published: December 2023

Abstract
Nowadays, more and more residents in Sichuan and Chongqing area choose to use gas for heating in winter, and the demand for gas is increasing. Therefore, it is necessary to improve the refined management of residential gas consumption. Firstly, this paper uses K-means clustering according to the gas consumption data from 2017 to 2021 provided by a company in Chengdu, so as to obtain the regulation of residents’ gas consumption. According to the different users’ gas consumption habits, the gas heating users in 2017 are identified. Then, a better SVM model is selected in SVM, KNN and logistic regression to classify the gas consumption data in 2018-2021. Finally, according to the classification results, the grey model is used to predict the number of gas heating users in the next two years, and compared with the real data in 2022, the results shows that the model effect is good. This study provides strong theoretical and technical support for gas companies to rationally plan gas consumption and optimize the operation of urban gas pipeline network.
From Zhentong Gao Method to Generalized Zhentong Gao Method
Authors: Xu Jiajin 
Published: December 2023

Abstract
It is found that the data of structural fatigue life are mostly in accordance with Weibull distribution rather than Gaussian distribution, but the biggest obstacle affecting the application of Weibull distribution is that the estimation of its three- parameters will encounter difficulties in mathematical derivation and complicated calculation. Based on the estimation of correlation coefficient, the author has proposed Zhentong Gao method (Z.T. Gao method) which can avoid these difficulties. Further research found that the idea of Z.T. Gao method can be used to directly calculate the maximum value of the likelihood function of three-parameter Weibull distribution and estimate the three parameters simultaneously, which is called Generalized Zhentong Gao method. At the same time, it is also found that Nonlinear Programming method and Boltzmann Annealing method in machine learning can estimate the three parameters of Weibull distribution by directly calculating the maximum of likelihood function, so they can be regarded as Generalized Z. T. Gao methods in a sense. The results obtained by these methods are compared and some enlightening conclusions are obtained.
Problems of Optimal Altitude Determination of Drones in Vertical Scanning Mode
Authors: Zu Yuran , Zhao Jianxin , Yan Panpan 
Published: December 2023

Abstract
This paper takes the UAV’s search for ship targets in the sea area as the background and uses the relationship between the probability of finding the target in the UAV’s radar imagery, the distance between the UAV and the target, and the UAV’s parameters, and according to the probability of the UAV finding a target based on multiple images. Taking the product of the discovery probability and the swept area as the index of search efficiency, the relationship between the probability of finding the target and the area of the swept sea area is balanced. The optimization model of the scanning sea area is established in the case of circular and rectangular to determine the optimal altitude of the UAV flights.
Research on Segmentation Methods of Horizontal Wells
Authors: Guo Songyi , Wang Zhiming , Shi Daju , Zeng Quanshu , Zhang Jianguo , Li Haitao , Deng Yunhui , Xue Heng 
Published: December 2023

Abstract
To equalize the inflow profile of horizontal well and reduce the influence of water breakthrough, the horizontal well should be divided into several sections. The problem of horizontal well segmentation can be classified into two types. The first one is how to segment with sufficient data, and the second one is how to segment with insufficient data. For the former, three segmentation methods have been proposed, named uniform segmentation method, ordered clustering segmentation method, and optimization segmentation method. In this study, for further indicate the application scope and condition of these three methods, the advantages and disadvantages of each method are fully studied. For the latter, the influence of reservoir parameter uncertainty should be considered. In this study, the segmentation method based on robust optimization is proposed to solve this problem. Assume that the horizontal well could be divided into 5 segmentations. For horizontal wells with sufficient data, three segmentation methods are discussed and compared through reservoir simulation. Results show that, in terms of cumulative oil production, the optimization segmentation method is the highest, followed by the ordered clustering segmentation method, and the uniform segmentation method is the lowest. In terms of simulation time, the optimization segmentation method is the longest because the optimal segmentation scheme will be found after iterative simulation. The ordered clustering segmentation method and the uniform segmentation method do not need iterations, so the segmentation scheme could be determined quickly. Therefore, if the computational cost is available, the optimization segmentation method is recommended; if not, the ordered clustering segmentation method is recommended. For horizontal wells with insufficient data, the segmentation method based on robust optimization proposed in this study has been proven to be effective, because the cumulative oil production of this method is greater than that of the uniform segmentation method. In conclusion, the segmentation strategies for horizontal wells with sufficient or insufficient data are presented and discussed. It will contribute to the completion design of horizontal well. Meanwhile, it will also help to delay water breakthrough and enhance oil production.
A Robust Localization Approach Based on Point Cloud Descriptor and SLAM in Urban Environment
Authors: Tian Shishang , Xie Zongxiu , Wu Lingzhi , Liu Chao 
Published: December 2023

Abstract
The importance of autonomous driving localization to autonomous driving systems cannot be overstated, reliable and high-precision localization is the focus of research in autonomous driving. Many studies at this stage use multiple sensors to generate high-definition maps for matching and localization. The labor and economic costs required to maintain such maps are often high. This paper proposes a fusion localization framework for simultaneous localization and mapping (SLAM) and matching localization. It could afford high-precision localization results of autonomous vehicles using only light detection and ranging (LiDAR) sensors. Concretely, a novel global point cloud descriptor, named binary scan context (BSC) is proposed, for matching localization. It encodes the structural features in the z-height direction in the point cloud space in a binary way. An efficient two-stage matching strategy is proposed to improve the efficiency of matching. Experiments on public datasets and vehicles have demonstrated the validation and precision of the method.
Simulation Study of Heat Flow Coupling of Thermal Barrier Coatings Based on Virtual Coating Technology
Authors: Guan Peng , He Jia-Ning , Ai Yan-Ting , Liu Yan-Ming , Yao Yu-Dong 
Published: December 2023

Abstract
To improve the simulation efficiencies and accuracy of heat flow coupling of thermal barrier coatings (TBCs), a nozzle guide vane model with virtual TBCs was established, by equivalent series thermal resistance theory and virtual TBCs modeling method. The difference in heat flow and temperature on the nozzle guide vane surface with real and virtual TBCs was discussed and analyzed. The results show that if the thickness of TBCs is less than 0.5mm, the temperature distribution of the virtual TBCs model is basically the same as the real one, the maximum relative deviation is less than 5%. The thermal resistance of TBCs is affected by the thickness and installation position of TBCs, when the thickness is 0.5mm, the maximum and minimum heat resistance of the TBCs is 40? and 5?, respectively. The efforts of this study provide a framework to predict the heat flow coupling of TBCs.
Droplet Collision of Dynamic SiO2 Superhydrophobic Surfaces
Authors: Li Wenhao , Cai Zishuo , Li Wenbo , Wang Pan , Zhang Aocheng 
Published: December 2023

Abstract
The droplet collision study on the dynamic superhydrophobic surface is of great significance in cleaning, corrosion, and other related fields and is one of the critical contents of the research. In this study, an investigation is carried out on the droplet rebound phenomena observed during collisions on a dynamic SiO2 superhydrophobic surface exhibiting a contact angle of 151°. Five different bounce kinds are shown in the results.Independent of the speed of surface motion, the Weber number causes a rise in the maximum spreading diameter of the droplet. As the speed of surface motion increases, the driving force of slip changes from shear force to lift force, and the slip distance increases rapidly with the speed of surface motion, and then increases slowly. The contact time decreases with an increase in the speed of the moving surface after the droplet strikes it, and the shear stress causes the droplet to deform asymmetrically, leading to quicker shrinkage. Three comparisons of theory, simulation and experiment are in good agreement.
Design of Simulation Software for Visualization of Munition Anti-Air Effectiveness
Authors: Cai Zilei , Chang Bo , Shi Rui , Gao Xiang , Wang Dongliang 
Published: December 2023

Abstract
In order to realize the simulation of the damage effectiveness of air defense projectiles against air targets, this paper uses the C++ programming language to complete the development of ammunition air damage simulation model by constructing the ammunition combat model and target vulnerability digital model, and designs the visualization simulation software of ammunition air damage effectiveness based on the Unity 3D engine. The results show that the visualization and simulation software of ammunition damage effectiveness against air targets can calculate the damage effect of ammunition on air and visualize the results of missile rendezvous, combat guidance and air target damage, which provides reference for the design of air defense ammunition introduction.
Study on the Characteristics of Gas Spring-Damping Modified Model Bladder-Damper Based on Dynamic Mesh Technology
Authors: Wang Xiaowei , Liu Wenxi 
Published: December 2023

Abstract
This paper addresses the existing difficulty in quantitatively analyzing and calculating the attenuation effect of a specific type of vibration control device, referred to as a “Bladder-Damper”. In response, a modified version of the “Gas Spring-Damping” model specifically tailored for this device has been proposed. Models involving both series and parallel connections have been established to support our work. Dynamic mesh technology has been used to simulate the damping characteristics of the Bladder-Damper, successfully resolving both finite element fluid calculation divergence issues and negative volume problems during dynamic mesh updating. By applying different pulse frequencies, dynamic simulations of the Bladder-Damper have been performed. The results demonstrate that our proposed modified model greatly reduces calculation errors associated with the traditional “Gas Spring-Damping” model. Interestingly, it has been noted that the damping effect on pressure pulsation is superior when using series dampers compared to parallel ones. The optimal attenuation effects occur when the frequency of fluid pulsation aligns with the resonance frequency of the damper, resulting in a maximum attenuation rate of up to 95%. The effectiveness and practicability of our simulation correction model have been confirmed since the simulation results align well with experimental outcomes. This establishes a new methodology and perspective for assessing the attenuation performance of the Bladder-Damper.
Study on Mechanical Properties of Steel Frame Structure with PEC Columns
Authors: Mao Yongsheng , Zhang Zhuanna , Yin Zhanzhong 
Published: December 2023

Abstract
PEC column has a wide prospect for strengthening existing steel structure buildings because of their high strength, stiffness, and bearing capacity. The seismic performance of the original steel structure could be significantly improved by filling the trough of section steel with concrete to form a partially encased composite column. Especially for multi-story buildings, the PEC column is an ideal edge restriction structural element, so it is of great significance to study its seismic performance. PEC column was introduced into steel frame structure, and six models of 8-story steel frame structures with PEC columns were established by using OpenSees finite element software. The displacement load curve, the maximum axial force in the column, the maximum bending moment at the column base, and the maximum inter-story shear force were obtained by Pushover analysis. The influence of concrete grade and the width-thickness ratio of the steel sheet of the PEC column on the mechanical properties of the whole structure was studied. Results show that lateral stiffness, ductility, and shear load-bearing capacity of the structure are improved with the addition of concrete in section steel, but ductility of the structure decreases with an increase of concrete strength grade. The influence of variation of PEC column parameters on the bottom of the structure is better than that on top. The width-thickness ratio of the section steel flange plays a major role in controlling the mechanical properties of the structure. The elastic stiffness of the structure, axial force of the column, and bending moment of the column base increase with the increase of flange thickness as section height is the same. An increase of the width-thickness ratio of the flange can improve the shear force of the story, and the lower the number of stories, the more significant the effect is.
Fire refugia are robust across Western US forested ecoregions, 1986–2021
Authors: Platt Rutherford Vance , Chapman Teresa B , Balch Jennifer K 
Published: December 2023

Abstract
In the Western US, area burned and fire size have increased due to the influences of climate change, long-term fire suppression leading to higher fuel loads, and increased ignitions. However, evidence is less conclusive about increases in fire severity within these growing wildfire extents. Fires burn unevenly across landscapes, leaving islands of unburned or less impacted areas, known as fire refugia. Fire refugia may enhance post-fire ecosystem function and biodiversity by providing refuge to species and functioning as seed sources after fires. In this study, we evaluated whether the proportion and pattern of fire refugia within fire events have changed over time and across ecoregions. To do so, we processed all available Landsat 4–9 satellite imagery to identify fire refugia within the boundaries of large wildfires (405 ha+) in 16 forested ecoregions of the Western US. We found a significant change in % refugia from 1986–2021 only in one ecoregion—% refugia increased within fires in the Arizona/New Mexico Mountain ecoregion (AZ/NM). Excluding AZ/NM, we found no significant change in % refugia across the study area. Furthermore, we found no significant change in mean refugia patch size, patch density, or mean distance to refugia. As fire size increased, the amount of refugia increased proportionally. Evidence suggests that fires in AZ/NM had a higher proportion of reburns and, unlike the 15 other ecoregions, fires did not occur at higher elevation or within greener areas. We suggest several possibilities for why, with the exception of AZ/NM, ecoregions did not experience a significant change in the proportion and pattern of refugia. In summary, while area burned has increased over the past four decades, there are substantial and consistent patterns of refugia that could support post-fire recovery dependent on their spatial patterns and ability to function as seeds sources for neighboring burned patches.
The Image of the New Johar Market – Aloon-Aloon District, Semarang
Authors: Kiswari MDN , Yuliastuti N , Sudarwanto B 
Published: December 2023

Abstract
Revitalization efforts showed a “new image”, namely as a resilient economic area, able to withstand environmental changes, safe and comfortable, which was part of sustainable development in urban areas. Semarang has been a trading city since the colonial era. One of the famous trading areas in Semarang is the Johar market district. The district has historical value. Up to now, this area is the largest traditional market in Semarang city. The Johar market building is one of the cultural heritage buildings in Semarang. There was such a big open space called Aloon-Aloon, near the Johar market. A big mosque, Kauman Grand Mosque, lies near the open space. The open space and the mosque have historical value in Semarang’s socio-cultural life. In May 2015, a big fire destroyed the buildings of Johar and Yaik markets. The building was reconstructed and renovated becoming a new Johar Market. In accordance with Aloon-Aloon’s concept, the former Yaik Market site was returned to be a public open space adapting to the current environmental and social conditions of society. In early 2022, the new market and the new public open space have been operated. This paper aims to describe images of the new Johar and Aloon-Aloon district. The paper implements a qualitative descriptive method for describing the current condition and using the theory of place related to the image of the district. The analysis utilizes pictures, and diagrams and is supported by the interview with the stakeholders. The results are a description of the new Johar – Aloon-Aloon district.