bluuebunny/crossref_metadata_2025_split huggingface dataset:
The fracture reason of high-pressure outer cylinder bolt
Authors: Lyu Lei , Wang Yingjun 
Published: September 2023

Abstract
The power plant experienced a cylinder bolt fracture accident during the power generation process of the unit. This study conducted fracture research and analysis on fractured bolts through a series of macroscopic and microscopic detection methods. The analysis results indicated that the cause of the bolt fracture accident of the high-pressure outer cylinder of the 5th steam turbine this time was the improper heat treatment process during the bolt material processing stage, which resulted in coarse grain size and severe insufficient impact toughness of the bolt material. Finally, the crack occurred at the position with the largest load and gradually expanded in a brittle manner until the overall fracture failure.
Analysis of cracking characteristics and mechanism of high-strength steel after chemical oxidation
Authors: Wu Liqun , Lu Yang , Zhu Lizhi 
Published: September 2023

Abstract
The tooth surface of the 20CrNi2Mo worm underwent cracking after chemical oxidation. The appearance inspection results showed that there were multiple cracks on the tooth surface of the worm slice, and the direction of the cracks was perpendicular to the machining pattern. There were many microcracks on both sides of the main crack. The profile morphology shows that the crack depth reaches 1100 μm. The crack extends perpendicular to the tooth surface to a certain depth and then propagates in two transverse directions. After opening the crack on the tooth surface, observation shows that the overall section is black, and the artificially opened area is silver-white. At the interface between the artificially opened area and the initial fracture surface, the fracture surface changes from intergranular morphology to ductile dimple morphology. The energy spectrum shows that the oxygen content in the intergranular cracking area is much higher than that in the ductile dimple area, indicating that the worm has undergone intergranular corrosion cracking. After the worm tooth surface is ground, there will be certain tensile stress on the surface. During the chemical oxidation process, the worm will be exposed to many corrosive media such as OH−, and NO2
−. Under the combined action of tensile stress and corrosive ions, the tooth surface will undergo stress corrosion cracking. To effectively avoid cracking on the worm gear surface, three measures have been proposed to reduce the risk of cracking: (1) improving machining parameters to reduce grinding feed, (2) increasing destressing before chemical oxidation to reduce residual tensile stress, (3) improving chemical oxidation process to reduce solution concentration, treatment time, and treatment temperature.
The structure and hydrophilicity of MWCNT-COOH /TiO2 modified PVDF membrane
Authors: Yang Hui , Wang Jianhua , Zhang Jiaqi 
Published: September 2023

Abstract
MWCNT-COOH/TiO2 modified PVDF ultrafiltration membrane was created using a blended modification process with carboxyl carbon nanotubes (MWCNT-COOH) and TiO2 nanoparticles as modification additives in order to further enhance the hydrophilicity of the PVDF membrane surface. Using the techniques of scanning electron microscopy, Fourier transform infrared spectrum, and a water angle of engagement analyzer, the membrane’s structure and hydrophilicity were identified. Investigations were conducted into the effects of various MWCNT-COOH dosages on membrane structure and hydrophilicity. The results of the investigation indicated that 0.03 g of MWCNT-COOH in the casting solution was the ideal dose. The manufactured MWCNT-COOH/TiO2 modified PVDF ultrafiltration membrane had the best hydrophilicity.
Fusion of Multi-scale Features Seal End Face Fluid Characterization
Authors: Fan Zhichao , Ahmat Mutellip , Zhang Tingkun 
Published: September 2023

Abstract
The composite weaving of dynamic and static ring friction end faces with multi-scale features can improve the sealing performance of mechanical seals, but there is no clear mechanism of weaving action, and it is difficult to optimize seal surface weaving. In this study, a mathematical model is developed to analyze the fluid sealing performance of the composite textured mechanical seal end face with a combination of a 5-sided micro-pit and T-slot according to the mass conservation cavitation boundary condition. The change in sealing performance between the composite texture and single texture in terms of opening force and leakage volume was investigated. Numerical analysis shows that compared with a single texture, the multi-scale texture end face creates a coupling effect between the micro-pit and T-slot, which has a stronger dynamic pressure lubrication effect and improves the sealing performance of the sealing sub-seal with increased pressure. The research results can be applied to the design optimization of mechanical seal surface textures.
ZSM-5 Templated Porous Carbon: Synthesis and Characterization
Authors: Qu Huiqi , Li Bin , Lv Zhiguo 
Published: September 2023

Abstract
Microporous zeolite ZSM-5 is prepared by the hydrothermal method, and its structure is tuned by changing the hydrothermal conditions. Then zeolite particles with uniform size and dispersion are etched into the hollow porous structures with an alkali solution to form zeolite templates. Porous carbon materials with ordered pore channels are acquired by the carbon deposition method (CVD). The detailed steps include introducing suitable carbon sources into the pore channels of the as-prepared zeolite templates, followed by carbon vapor deposition and continuous optimization of the deposition conditions, and finally, removing the template. The hollow porous structure of the carbon material facilitates the exposure of catalytic active sites and the improvement of diffusion kinetics. The hollow porous carbon (HPC) formed by carbon deposition perfectly inherits the structure and pore attributes of the hollow hierarchical zeolite ZSM-5. It can be further used as a carbon-based catalyst support.
The Influence Factors of Incremental Forming Geometric Accuracy based on the Weighted Gray Correlation Analysis Method
Authors: Xu Hu , Sun Li Zhong , Gu Peng , Wang Bai Chao 
Published: September 2023

Abstract
In view of the process complexity of the pillow effect phenomenon, the orthogonal experiment was designed, and the numerical simulation of the single-point incremental forming process under various process parameters was carried out by using the finite element software. Taking the height of the specific position (i.e., bulging) of the pillow effect phenomenon as the evaluation index, the data were analyzed based on the weighted gray correlation analysis method. The influence of the forming height, sheet thickness, forming angle, layer feed, tool head diameter, and part size process parameters on the forming geometric accuracy was studied. The optimal process parameters of single-point incremental forming and the primary and secondary order of the influence on the evaluation index were obtained. The results show that the weighted gray correlation analysis can effectively reduce the geometric error of the pillow effect phenomenon form of the target part and improve the forming accuracy.
Thermal lubrication characteristics of hypoid Gear with non-Newtonian fluids considering roughness
Authors: Sun Peng , Xu Zhan , Feng Zhongyi , Wang Kai , Gao Hongbiao , Wang Zhiming , Yu Zhuoyue 
Published: September 2023

Abstract
Based on Hertz contact theory and EHL, the model of elliptic contact elastohydrodynamic lubrication considering load, speed, roughness, thermal effect, and shear-thinning effect of non-Newtonian fluids is established. The variation trend of oil film pressure, thickness, and temperature with load, entrainment velocity, and the slide-roll ratio is analyzed. Then, several lubrication states considering roughness, the thermal effect, and the characteristics of non-Newtonian fluid are compared. Compared with the smooth surface, the roughness when RMS is 0.15 μm increases the maximum film pressure (P
max) by 8.34%, increases the maximum film temperature (T
max) by 7.18%, and reduces the minimum film thickness (H
min)by 9.13%. The pressure and temperature are more sensitive to light load. The results are approximate to that of the smooth surface when the entrainment velocity is big enough. The pressure and thickness decrease with the increasing slide-roll ratio. The decreasing speed of the oil film thickness becomes faster as a result of the thermal effect. The roughness and the characteristics of non-Newtonian fluid have a significant impact on temperature.
Study on preparation technology of large bimetal composite wear-resistant elbow
Authors: Zhang Mingyi , Gao Ping , Jia Xiaobin , Wang Wei , Sun Quanxi , Li Shuli 
Published: September 2023

Abstract
Large - scale bimetal composite wear-resistant elbow was fabricated by lost - die casting,the non-working layer of the outer wall of the bend was made of 16Mn steel pipe, and the inner working layer was made of high chromium cast iron. This paper introduced the preparation technology and method of elbow from the aspects of material composition selection, melting process, lost mold casting process and heat treatment process, analyzed and solved the problems of box collapse and box expansion in the casting process. The wear test shown that the wear resistance of bimetallic composite elbow was twice that of 16Mn material elbow. The service life of the composite elbow was 2~3 times that of the original single material elbow.
Electro-spun Sn nanoparticles encapsulated in N-doped carbon nanofibers as flexible integrated anodes for high-efficiency lithium-ion batteries
Authors: Shao Qi , Liu Jiaqi , Yang Xiantao , Li Yan 
Published: September 2023

Abstract
The anode electrode substances of lithium-ion batteries (LIBs) are indispensable for the insertion and elimination of Li+. Herein, we combine electrospinning technology and heat treatment method to encapsulate Sn species in nitrogen-doped carbon nanofibers (Sn/NCNFs). During the experiment, we selected polyacrylonitrile (PAN) as the precursor solution, tetraphenyl porphyrin (TPP) as the N source and SnCl2·as the Sn source. The obtained one-dimensional structure no longer only successfully reduces the giant extent modifications of Sn species in the course of cycling, but additionally achieves fast Li+/e− transportation. Moreover, the introduction of N atoms causes more defects in carbon nanofibers, providing additional storage sites for Li+. Thus, the Sn/NCNF-0.168 exhibits favorable reversible capacity (~581.7 mAh g−1 at 1 A g−1) and cycling stability (over 250 cycles). This work gives an advantageous strategy to design high-performance anode electrode substances for LIBs and lays the foundation for future energy applications.
Bearing stress detection and evaluation of hydraulic steel gate members
Authors: Li Qin , Ding Peng , Ji Jiankang , Yu Pengxiang 
Published: September 2023

Abstract
Based on the principle of mathematical statistics, we describe the theory and algorithm of establishing the stress characteristics of gate members by using the method of data regression analysis based on multiple levels of actual load detection data. Following, we demonstrate the test results of an arc gate of a spillway dam by regression analysis. Then, we calculate the structural stress state under the design condition by regression equation, and the finite element results are used to verify each other. Finally, according to the current standard, we give the safety evaluation of the structure stress calculation data under the design condition.
The study of X-ray full-field imaging method for low atomic number elements based on Compton scattering
Authors: Jia Wenbao , Zhang Zhanpeng , Zhang Xinlei , Luo Yangxue , Ling Yongsheng , Hei Daqian , Shan Qing , Zhang Jiandong , Shi Chao 
Published: September 2023

Abstract
Full-field X-ray fluorescence imaging cannot image low
atomic number (Z < 12) materials because the characteristic X-ray
fluorescence produced by low atomic number (Z < 12) materials is
severely attenuated in air. In this paper, we propose a method to
combine Compton scattering with full-field X-ray fluorescence
imaging, which can realize the imaging of both metals (high atomic
number) and organic materials (low atomic number), and compensate
the defect that the conventional FF-XRFI technique cannot image
materials with low atomic number such as organic materials. The
imaging experiments were performed using two materials, zirconium
metal and polyethylene, and the imaging results were optimized using
a density filtering algorithm, and the results indicate that it is
possible to use this method to image samples of high and low atomic
number with resolution.
Examining past and projecting future: an 800-year streamflow reconstruction of the Australian Murray river
Authors: Higgins P A , Palmer J G , Andersen M S , Turney C S M , Johnson F , Allen K , Verdon-Kidd D , Cook E R 
Published: September 2023

Abstract
Managing water security and sustaining ecosystem functions under future warming poses substantial challenges for semi-arid regions. The Murray–Darling Basin (MDB) is particularly vulnerable given the considerable demand for water that underpins Australia’s agricultural production and contribution to the national economy. Understanding future drought risk requires a robust assessment of natural variability in drought length, frequency, and magnitude. In the absence of long instrumental records, past drought characteristics can be inferred from paleo-records. We reconstruct over 800 years of Murray River streamflow using a suite of tree-ring chronologies from regions with strong climate teleconnections to the MDB. The reconstruction (1190–2000 CE) captures a broad spectrum of natural climate variability, not fully represented in instrumental records, contributing to an improved understanding of the occurrence rate of multi-year droughts. We found that the Millennium Drought, which occurred in the 2000s, was the most severe (joint duration, magnitude, and peak) during the 800-year reconstruction. The return period of this event is estimated to be ∼2500 years. However, droughts in the early-1200s were of a longer duration and similar magnitude to the Millennium Drought. We used climate models to assess how the occurrence probability of severe droughts might change in the future. Compared to the 800-year baseline, climate models project an increase in future drought severity. While the increase in drought occurrence is within the uncertainty range for most future projections, the driest forecast shows a significant increase in the likelihood of severe droughts compared to natural variability. Our results highlight the need for water management strategies not to rely solely on instrumental data as it may not fully represent current and future risks. Ensuring a resilient MDB under future warming will require a robust water security policy that captures a broader range of natural and anthropogenic variability than currently recognised.
Study assessment of water electrolysis systems for green production of pure hydrogen and natural gas blending
Authors: Gavrailov D Y , Boycheva S V 
Published: September 2023

Abstract
Hydrogen and hydrogen blended energy carriers are considered the main decisions for production of low-carbon and carbon-free energy. The green hydrogen production is still a small share compared to other hydrogen production methods and necessity of water electrolysis’s improvements is needed. This article aims to introduce the most developed electrolyzers as alkaline (AWE), proton exchange membrane (PEM) and solid oxide water electrolysis (SOWE) comparing them in different categories in order to assess advantages and disadvantages of each one. Comparing the most used method of hydrogen production such as steam reforming with water electrolysis shows that using hydrogen generated by natural gas steam reforming does not really reduce overall CO2. Mixing hydrogen with up to 20 % with natural gas does not require infrastructure changes and leads to 6.5 % reduction in CO2 emissions. The fuel characteristics of hydrogen and its influence on the properties of natural gas blending were also summarized.
Simple improvements for decentralized air handling unit for regenerative heat recovery
Authors: Penev A D , Tsokov L P , Shushulov K K 
Published: September 2023

Abstract
This paper presents the optimization of a fixed regenerative heat exchanger for a decentralized air handling unit (AHU) and a simple algorithm for its control. The influence of the geometric characteristics of the regenerative matrix and the duration of the airflow switching periods on thermal efficiency was analyzed. For this purpose, a numerical analysis using the finite volume method of the ANSYS, Fluent software was used. The simple logic of control is proposed as a result of field experiments and numerical analysis based on close-to-real operating conditions. The control algorithm prevents the operation of the device in case of a significant imbalance of the air flows and in case of a strong deterioration of the efficiency of the regenerator as a result of the presence of condensation of water vapour in the airflow through the regenerator.
Indices for ventilation efficiency and their numerical computation
Authors: Pichurov George T 
Published: September 2023

Abstract
The paper addresses methods to evaluate the ventilation efficiency both in regard to air exchange and to contaminant removal in a room. Extra variables are introduced via transport differential equations which are solved by Computational Fluid Dynamics (CFD). Ventilation efficiency indices are defined and computed by alternative methods with an excellent agreement. For the numerical calculations a test chamber with a fume cupboard has been modelled and simulated. The paper discusses peculiarities in the calculation of the passive scalar equations to ensure mass conservation. Guidelines for optimal locations of the exhaust grilles of ventilation systems have been proposed to maximize ventilation efficiency.
Comparative analysis of the energy performance of an air handling unit with two-stage heat recovery operating in the different climatic zones of Bulgaria
Authors: Dimchev Ivan 
Published: September 2023

Abstract
A comparative analysis was carried out to establish the energy performance of an air handling unit (AHU) for two-stage heat recovery of the exhaust air. The seasonal coefficient of performance (SCOP) was calculated when AHU is operating in heating mode, as well as COP for the entire unit on an annual basis, taking into account the specific features of the different climatic zones in the Republic of Bulgaria. The results have been compared with the BIN-temperature data for an average climate provided in EN 14825 (Table 37) in order to find out how far this standard will give reliable results for the Bulgarian climate, both in terms of energy consumption and SCOP.
Axial-piston pump optimal multivariable PID controller tunning
Authors: Mitov A , Slavov Ts , Kralev J , Angelov Il 
Published: September 2023

Abstract
The aim of the present work is the synthesis and optimal tunning of a PID controller designed to control the displacement volume of an axial-piston pump intended for hydraulic systems with open circulation. The pump is controlled in real-time through a system developed by the authors based on an electro-hydraulic proportional valve (replacing the conventional hydro-mechanical controller) and an industrial controller. The experimental system was initially used to obtain a data set that is used in a system identification procedure to obtain a model. The obtained state space model was used for the synthesis of the PID controller. The optimal tunning of controller parameters is performed using three modern methods: genetic algorithm, simulated annealing and pattern search. The resulting three PID controllers with different settings depending on the used methods are compared in simulation and experimental conditions. Based on the results, an analysis of the control performance was carried out.
Study of the aerodynamics of air flow in burners using the Comsol Multiphysics software
Authors: Makzumova A K , Sarakeshova N N , Dostiyarov A M , Iliev I K 
Published: September 2023

Abstract
The article presents the processes of modeling the aerodynamic flow of air in two burner microflame devices: 1. The burner device of the combustion chamber of a gas turbine plant; 2. The micromodular gas burner. The aerodynamic flow is modeled in the Comsol Multiphysics software package, which is reasonable in terms of availability and quality. The performed analysis of microflame fuel-burning devices revealed that the dynamic and geometric characteristics affect the aerodynamics and velocity profiles. Different airflow rates significantly affected the intensity of the formation of recirculation zones, which also led to an increase in pressure in the circuit. Accordingly, the flow at different heights of the cylindrical nozzle showed that the dimensions will affect the combustion processes and, as a result, the stabilization and formation of nitrogen oxides.
Eco-sustainability of cotton textiles: moisture absorption case study
Authors: Angelova Radostina A. , Sofronova Daniela 
Published: September 2023

Abstract
Moisture absorption is a crucial property of cotton fabrics, as it directly affects their comfort and performance in various applications, as well as fabric’s degradation. While the moisture absorption ability of cotton fibres has been extensively studied, the influence of the geometric, structural, and mass characteristics of cotton fabrics on their moisture absorption capacity remains less explored. Therefore, this paper aims to investigate the relationship between these fabric parameters and moisture absorption to identify additional factors contributing to cotton fabrics’ overall moisture absorption ability.
Sustainable fashion with elements of the Bulgarian national garb–reducing, reusing and recycling through mulage method
Authors: Pavlova Magdalena , Ivanova Ivelina 
Published: September 2023

AbstractA Communication from the European Commission in Brussels, dated 30 March 2022, to the European Parliament, the European Council, the Council, the European Economic and Social Committee and the Committee of the Regions, presents an EU Strategy for Sustainable and Circular Textiles as a standard. In line with the strategy, this paper is aimed at creating women’s clothing with elements of the Bulgarian national garb, bearing the characteristics of sustainable fashion. The design and manufacturing of the models is realized through the methods upcycling and mulage, looking for the effect of 3’R’s – Reduce, Reuse, Recycle. The models are segmented appropriately to combine several products in a common vision. The artistic design is realized trough image creation and processing software. The technology was developed with graphics software.
Influence of electric field on the thermal properties of PP+NC nanocomposites for environmental chemistry application
Authors: Hadiyeva A.A. , Mammadova Sh.R. , Mahmudzade L.R. 
Published: September 2023

Abstract
Using Differential Thermal Analysis (DTA) method the thermal-physical properties of nanocomposites PP+NC for environmental and environmental chemistry applications were studied and the thermal-destruction processes after aging in an electric field were determined. The influence of various external factors (strong electric field, electric discharge, temperature, radiation, etc.) on polymers and composites based on polymers penetrates into the deep layers of the matrix and leads to the destruction and reconstruction of the structure. Changes in the ratio of crystalline and amorphous phase occur due to the formation of an interlayer crystalline phase in the matrix. In this regard, the thermal properties of pure PP and PP+2.0% NC nanocomposites were investigated using the derivatographic method to study the influence of the electric field on the aging process, melting temperature, and crystallization rate and depolymerization process.