bluuebunny/crossref_metadata_2025 huggingface dataset:
ARIMA with Attention-based CNN-LSTM and XGBoost hybrid model for stock prediction in the US stock market
Authors: Liang Luocheng
Published: August 2024

Absteact: Stock price forecasting is considered one of the most difficult tasks in financial forecasting. Combining ARIMA with neural networks helps to enhance the model’s predictive capabilities when dealing with complex, nonlinear time series data. Attention-based CNN-LSTM and XGBoost hybrid model achieves the accuracy of stock prediction results. However, the predictive effect of this hybrid model has only been confirmed by Chinese stock market data. Therefore, this paper proposes to use ARIMA with Attention-based CNN-LSTM and XGBoost hybrid model to predict the stock price of five different types of companies in the US stock market. Experimental results show that this hybrid model performs well in the training phase and has small prediction errors. However, during the testing phase, the model performs better in predicting stocks with larger price fluctuations, while the prediction error for stocks with more stable prices increases significantly. This shows that this hybrid model has good predictive ability when dealing with stocks with large market fluctuations, but it still needs further optimization for stable stocks. This study further demonstrates the potential of this hybrid model in stock price prediction, especially during market fluctuations, as it can be used as an effective tool to avoid risks and obtain returns.
Predict stock market price by applying ANN, SVM and Random Forest
Authors: Ji Sicheng
Published: August 2024

In this modern society, stock market has become one of the most significant things for both person and unity, which can make huge influence. Therefore, more and more researchers attempt to invent useful models to assist them to gain benefits. After scholars’ efforts, people discover that machine learning is an effective model to forecast the price, and ANN, SVM, RF are three famous machine learning models. They are always applied for predicting stock products price. This essay will discuss which model can predict price better to provide assistance to investors. The research depends on data in google scholar and uses a website called colab to analysis the effects of these models and find the better model(s). In this paper, gold price and several enterprises’ historical stock price is used to find out what results can these models provide. We will use trained models and the results will be shown by coordinate maps. In the research, we find that RF is the best model when doing prediction, it obvious has better effects. RF can make forecast more accuracy than other two machine learning models. Hence, for those three machine learning models, Random Forest model can provide better assistance when people want to predict stock price. It means that if investors or companies are eager to obtain wealth or have more advantages in stock market, Random Forest model can be a helpful choice. It is recommended to use this model in the region of stock market.
Analysis of corporate governance and corporate sustainability performance in China
Authors: Yu Lijie , Huang Chengxuan
Published: August 2024

This study examines the relationship between corporate governance (CG) and corporate sustainability performance (CSP) in Chinese A-share listed corporations from 2016 to 2022. Using regression analysis, it explores how board attributes, executive incentives, and equity structure influence economic, environmental, and social sustainability performance. The findings show that while board attributes positively impact economic sustainability, their effects on environmental and social sustainability are mixed. Executive incentives strongly correlate with all sustainability dimensions, emphasizing the importance of aligning compensation structures with sustainability goals. Concentrated ownership positively affects economic performance but may hinder environmental sustainability. However, it marginally contributes to social sustainability. This research sheds light on the interplay between CG and CSP in China, offering insights for policymakers and corporate leaders aiming to enhance sustainability practices.
The influence of leader-member exchange social comparison on employee innovative behavior
Authors: Chen Yuhong , Liu Bing
Published: August 2024

Based on the job demands-resources model, the mechanism and boundary conditions of leader-member exchange social comparison on employee innovative behaviors were tested with self-efficacy and role load as mediating variables and error management climate as moderating variables. Based on the empirical analysis of 452 questionnaire data collected in two stages, it is found that self-efficacy and role load play a partial mediating role in the relationship between leader-member exchange social comparison and employee innovative behavior. Error management climate positively moderates the relationship between leader-member exchange social comparison and self-efficacy, and positively moderates the mediating role of self-efficacy in the relationship between leader-member exchange social comparison and employee innovative behavior. Error management climate negatively moderates the relationship between leader-member exchange social comparison and role load, and negatively moderates the mediating role of role load in the relationship between leader-member exchange social comparison and employee innovative behavior.
Innovative Practices for IoT Scenarios: A Case Study of Driverless Shared Cars
Authors: Lai Weijie , Wang Yuying
Published: August 2024

As a new type of digital product, driverless shared cars will become an important part of the intelligent public transportation system. This paper aims to use driverless shared vehicles to carry out a comprehensive digital transformation of transportation, that is, to remotely control the driverless through the man-machine interface, and turn the taxi into a remote-controlled car controlled by a remote center. Compared with existing technology and business models, the technical framework and operational idea of driverless shared cars proposed in this paper have great advantages. It can not only reduce per capita carbon emissions and travel costs, but also promote efficient management of transportation and cities. This study can be also adapted to various countries in the world due to its flexibility. After summarizing and analyzing different driverless and shared car technology schemes, this paper predicts the profitability of cruise taxis after adopting this model, puts forward feasible design schemes, and looks forward to its development prospects all over the world.
Problems and Optimizing Strategies of Primary School Students’ Mental Health Education
Authors: Yan Mohan
Published: August 2024

This article aims to explore the problems and optimization strategies in primary school students’ mental health education. After analyzing the current status of mental health education for primary school students, the article will employ a literature review method to analyze the issues related to the weak teacher workforce, insufficient school emphasis, and family factors. By strengthening professional training to enhance the professional competence of educators, actively transforming teaching philosophies to prioritize mental health education, and promoting home-school cooperation to integrate mental health education into various subjects, these optimization strategies can effectively improve the current status of mental health education for primary school students. The research findings indicate that the current mental health education for primary school students faces problems such as a weak teacher workforce, insufficient school emphasis, and family factors. However, through the implementation of optimization strategies, the professional level of educators can be enhanced, and home-school cooperation can be promoted, thereby effectively improving the mental health education for primary school students. The study suggests that the aforementioned optimization strategies provide some guiding recommendations for mental health education for primary school students and have a certain impact on promoting their mental well-being.
Bodenhaftung durch Wurzelöle
Authors: Zimmermann Eliane
Published: August 2024

Mit ihren besonderen Inhaltsstoffen und eigenwilligen Düften vermitteln ätherische Wurzelöle insbesondere „verwurzelnde“, beruhigende und haltgebende Eigenschaften. Das schlaffördernde Öl des „unverwüstlichen“ tropischen Süßgrases Vetiver gilt mit einem der schwersten bekannten Pflanzendüfte als „Holzhammer der Aromatherapie“, während das kostbare, aufwendig gewonnene Öl der Iriswurzel Trost bei Verlust spendet und Prostatabeschwerden lindert. Das schützende Öl der Engelwurz (Angelika) dient als Kraftöl zur Rekonvaleszenz bei Infekten und Burnout, aber auch bei chronischen Schmerzen, Entzündungen und als Nasenbalsam.
Wurzel mit Riechfunktion
Authors: Corts Magga
Published: August 2024

Dysfunktionen der Nasenwurzel und angrenzender Strukturen können zu Riechstörungen führen. Eine Ursache für Dysfunktionen der Nasenwurzel können Traumata wie Überdehnung, Ausriss und Durchtrennung sein. Osteopathische und weitere Behandlungstechniken dienen unter anderem der Befreiung der Suturen, Anregung der Mikrozirkulation und der Lösung intraossärer Kompressionen.
Observational evidence for groundwater influence on crop yields in the United States
Authors: Deines Jillian M. , Archontoulis Sotirios V. , Huber Isaiah , Lobell David B.
Published: August 2024

As climate change shifts crop exposure to dry and wet extremes, a better understanding of factors governing crop response is needed. Recent studies identified shallow groundwater—groundwater within or near the crop rooting zone—as influential, yet existing evidence is largely based on theoretical crop model simulations, indirect or static groundwater data, or small-scale field studies. Here, we use observational satellite yield data and dynamic water table simulations from 1999 to 2018 to provide field-scale evidence for shallow groundwater effects on maize yields across the United States Corn Belt. We identify three lines of evidence supporting groundwater influence: 1) crop model simulations better match observed yields after improvements in groundwater representation; 2) machine learning analysis of observed yields and modeled groundwater levels reveals a subsidy zone between 1.1 and 2.5 m depths, with yield penalties at shallower depths and no effect at deeper depths; and 3) locations with groundwater typically in the subsidy zone display higher yield stability across time. We estimate an average 3.4% yield increase when groundwater levels are at optimum depth, and this effect roughly doubles in dry conditions. Groundwater yield subsidies occur ~35% of years on average across locations, with 75% of the region benefitting in at least 10% of years. Overall, we estimate that groundwater-yield interactions had a net monetary contribution of approximately $10 billion from 1999 to 2018. This study provides empirical evidence for region-wide groundwater yield impacts and further underlines the need for better quantification of groundwater levels and their dynamic responses to short- and long-term weather conditions.
Therapeutic delivery of CCL2 modulates immune response and restores host–microbe homeostasis
Authors: Shehabeldin Mostafa , Gao Jin , Cho Yejin , Chong Rong , Tabib Tracy , Li Lu , Smardz Matthew , Gaffen Sarah L. , Diaz Patricia I. , Lafyatis Robert , Little Steven R. , Sfeir Charles
Published: August 2024

Many chronic inflammatory diseases are attributed to disturbances in host–microbe interactions, which drive immune-mediated tissue damage. Depending on the anatomic setting, a chronic inflammatory disease can exert unique local and systemic influences, which provide an exceptional opportunity for understanding disease mechanism and testing therapeutic interventions. The oral cavity is an easily accessible environment that allows for protective interventions aiming at modulating the immune response to control disease processes driven by a breakdown of host–microbe homeostasis. Periodontal disease (PD) is a prevalent condition in which quantitative and qualitative changes of the oral microbiota (dysbiosis) trigger nonresolving chronic inflammation, progressive bone loss, and ultimately tooth loss. Here, we demonstrate the therapeutic benefit of local sustained delivery of the myeloid-recruiting chemokine (C-C motif) ligand 2 (CCL2) in murine ligature-induced PD using clinically relevant models as a preventive, interventional, or reparative therapy. Local delivery of CCL2 into the periodontium inhibited bone loss and accelerated bone gain that could be ascribed to reduced osteoclasts numbers. CCL2 treatment up-regulated M2-macrophage and downregulated proinflammatory and pro-osteoclastic markers. Furthermore, single-cell ribonucleic acid (RNA) sequencing indicated that CCL2 therapy reversed disease-associated transcriptomic profiles of murine gingival macrophages via inhibiting the triggering receptor expressed on myeloid cells-1 (TREM-1) signaling in classically activated macrophages and inducing protein kinase A (PKA) signaling in infiltrating macrophages. Finally, 16S ribosomal ribonucleic acid (rRNA) sequencing showed mitigation of microbial dysbiosis in the periodontium that correlated with a reduction in microbial load in CCL2-treated mice. This study reveals a novel protective effect of CCL2 local delivery in PD as a model for chronic inflammatory diseases caused by a disturbance in host–microbe homeostasis.
Early archaeological evidence of wheat and cotton from medieval Ile-Ife, Nigeria
Authors: Logan Amanda L. , Chouin Gérard L. , Ogunfolakan Adisa B. , Lally Shannon , Kuma Dela , Kuto Eli , Bell Kristina , Rosenzweig Melissa S. , Beldados Alemseged
Published: August 2024

This study reports the earliest directly dated occurrence of archaeological wheat and cotton in the humid forests of West Africa. These are the first archaeobotanical results from the medieval urban center of Ile-Ife, southwestern Nigeria, best known for its famous artworks. Both wheat and cotton likely spread through trans-Saharan trade networks that laid the foundation for later European trade systems. Forty-eight (48) grains of free-threshing wheat (
Triticum aestivum/durum
) represent the largest assemblage of wheat recovered in sub-Saharan West Africa, which is surprising given that wheat cannot be cultivated locally. Larger quantities of cotton (
Gossypium
sp.) recovered from late 12th- to early 13th-century CE contexts suggest earlier and more widespread use than wheat. Cotton may have been cultivated and manufactured into cloth locally. The quick adoption of these exotic crops illustrates the active negotiation of prestige through culinary and adornment practices, as well as a high degree of agricultural experimentation.
A LoRa-based safety monitoring system for hydrogen compressed natural gas (HCNG)
Authors: Wang Wenbo , Niu Pingjuan
Published: August 2024

Hydrogen compressed with natural gas pipeline for gas mixture delivery is an effective way to realize large-scale, low-cost delivery of hydrogen. The Internet of Things (IoT) technology is one of the important supporting technologies for smart energy transformation, and the low power wide area network (LPWAN) represented by LoRa will play a key role. In this paper, a LoRa-based hydrogen compressed natural gas safety monitoring system is designed, which can collect, transmit, and analyze multiple types of data, such as ambient temperature and humidity, gas concentration, pipeline and equipment vibration, etc., and store the data and configure the alarm thresholds through the cloud server, and finally complete the real-time safety monitoring in the application layer. The system is characterized by high efficiency, high precision, low power consumption, and intelligence, which will have a positive effect on the safe transportation of hydrogen.
Optimizing the performance of Inverted FASnI3-based perovskite solar cells by device simulation
Authors: Xu Zhiqi , Qin Qi
Published: August 2024

The tin-based PSCs (perovskite solar cells), with low toxicity and excellent photovoltaic properties, offer a promising solution to lead environmental pollution and toxicity issues, emerging as a strong substitute for environmentally friendly lead-free PSCs. However, tin-based PSCs still face significant challenges in terms of low power conversion efficiency and poor long-term stability. Therefore, in-depth research on tin-based PSCs is required to further enhance their performance. In this study, we utilize SCAPS-1D to simulate the currently efficient inverted FASnI3-based PSCs and determine the PSCs device parameters that are as close as possible to the results in published experiments. The simulation results indicate that the parameter adjustment of the absorption layer plays a vital role in the inverted device. Those parameters are thickness, defect density, and doping concentration. Similarly, parameter variations of other layers (parameters such as electron affinity, thickness, and doping concentration) and interfaces (parameters are defect density at different interfaces) are considered. We achieve a final optimized simulated device power conversion efficiency of 18.219%. This research aims to contribute to the future development of inverted FASnI3-based PSCs.
Study on the mechanical properties of micropore organic polymer membranes
Authors: Liu Jianxin , Kang Tingshuo , Yu Hualong , Li Xiang , Zhang Xiaolei , Deng Xiaoqing
Published: August 2024

Micropore organic polymer membranes are indispensable for membrane filtration with well-established selectivity and permeability. Pressure-driven conditions in harsh acidic or alkaline environments can influence the mechanical properties of these materials. Diminished mechanical properties may include a shortened membrane lifespan, reduced filtration effectiveness, and increased filtration cost. Understanding of the intricate mechanisms influencing the mechanical properties of organic polymer membranes remains incomplete. In this study, a comprehensive investigation was carried out to characterize the mechanical properties of different membrane materials with similar and varying pore size parameters. The influence of different methods of membrane preparation on the mechanical properties of these materials was also explored. Results showed that the PTFE membranes demonstrated excellent Young’s modulus and tensile strength, while PVDF membranes excelled in elongation at break. Organic filter membranes prepared by the phase transition method exhibited a more structured fiber filament arrangement, a smoother surface, reduced crack formation and extension, and uniform pore size and distribution when compared to materials prepared using the tensile method. The results of this study expanded our understanding of the factors that can influence the mechanical properties of organic filtration membranes.
Quantitative analysis of pA66/PA6 blend by pyrolysis gas chromatography-mass spectrometry
Authors: Bai Qinghua , Zhang Yin , Luo Chuan , Ye Hailei , Wang Hao , Yuan Lifeng
Published: August 2024

A pyrolysis gas chromatography-mass spectrometry method using correction factor area normalization was applied for quantitative analysis of the PA66/PA6 blend ratio. The PA66/PA6 blend sample with known proportions was prepared. The pyro grams of the sample were obtained at the pyrolysis temperature of 600°C. The characteristic peaks-cyclopentanone and caprolactam of thermally decomposed polyester were selected as the peak to quantitatively determine the blending ratio. A correction factor of the characteristic ion peak area and corresponding mass was obtained and applied to quantitative analysis of the proportion of PA66/PA6 blends in the actual sample. The known content PA66/PA6 blend samples with different PA66/PA6 bending ratios were measured, the rate of recovery was from 96.5% to 106.4%, and the relative standard deviation (RSD) was from 0.8% to 7.6% (n = 3). The result showed that the Pyrolysis Gas Chromatography-Mass Spectrometry method is simple and convenient, accurate, which is suitable for the analysis of the PA66/PA6 blending ratio in the full range.
A device for real-time detection of gas generated from commercial lithium-ion cell
Authors: Hao Weijian , Liu Shaohui , Niu Pingjian , Ma Tianyi , Han Ce , Zheng Tianlei
Published: August 2024

Lithium-ion batteries generate a large amount of flammable and toxic gases under abuse conditions. Research on the detection methods of gas generation from batteries is of great significance for understanding the reaction mechanism of batteries under abuse conditions, assessing the impact of gas generation on the health of occupants, and developing safer battery products. However, there is a lack of research reports on the real-time gas production behavior of commercial batteries. In this paper, a device for real-time detecting the gas component of the cylindrical lithium-ion cell is designed. Combined with a gas mass spectrometer can implement the real-time detection of the gas component of the lithium-ion cell. The device is used to explore the gas generation characteristics of lithium-ion cells in the overcharged state, and the influence of the material system and the degree of aging on the results are analyzed, verifying the feasibility of the device.
Preparation of eggshell-based materials and their adsorption performance on Fe(III) in water*
Authors: Zhang Xiaowen , Zou Jiajun
Published: August 2024

If there is too much trivalent iron in the body, it will disrupt the balance of osmotic pressure inside the body, and its heavy metal properties will denature proteins. Therefore, effective management of industrial pollution source wastewater is very important for environmental protection and human’s health. Calcium carbonate particles have a good ability to adsorb trivalent iron in wastewater. The aim is to prepare porous calcium carbonate by a template method using eggshell powder, hydrochloric acid, sodium stearate, and anhydrous sodium carbonate solution as the raw materials and research the adsorption properties of porous calcium carbonate to trivalent iron. Porous calcium carbonate was prepared by a template method using eggshell powder, hydrochloric acid, sodium stearate, and anhydrous sodium carbonate solution as the raw materials. The morphology and adsorptive properties of Fe (III) of the porous calcium carbonate were analyzed by scanning electron microscope (SEM) and UV-visible spectrophotometer (UV). The best value was found between different temperatures, time, and pH. The results verified that the maximum amount of adsorption was obtained when calcination was 400°C, pH was 5, time was 60 min, and the input amount was 20 mg. The adsorption of porous calcium carbonate to Fe (III) is chemical and has a better adsorption effect.
Inundation correlation research on the simulation of two-phase flow and heat transfer in a condenser
Authors: Wang Xiongshi , Zhan Tengteng , Dai Shoubao , Zhang Guihua , Wu Jiahao , Wu Yuxin
Published: August 2024

The performance of the condenser is important to keep the high efficiency of the instrument that converts thermal energy to power through steam. On the shell side of the condenser, there is a complex gas-liquid two-phase flow with coupled turbulence, phase change, and multi-component effects. Meanwhile, heat transfer and fluid flow are mutually coupled and interact with each other. This study carefully investigates a significant factor affecting the accuracy of two-phase model simulations in condensers. It’s found that the correction of the thermal resistance of the condensate plays a key role in good production. Starting from more accurate CFD calculation results of the two-phase flow, a method is derived that utilizes the liquid phase volume fraction for the correction. The simulated results obtained using this method show promising improvements compared to the complex approaches used by previous researchers.
Analysis of combustion characteristics of ammonia/hydrogen mixed fuel in HCCI engine
Authors: Nie Tao , Zhang Ping , Yang Kun , Zhao Jianhua , Zhou Lei , Wu Xin , Zheng Xiangquan , Luo Li
Published: August 2024

A zero-dimensional HCCI combustion model for ammonia/hydrogen mixed gases was established to study the influence of hydrogen on the combustion characteristics of ammonia fuel. The effects of compression ratio, intake temperature, and hydrogen ratio on the combustion performance of ammonia were analyzed. The results suggest that due to the high ignition point of ammonia, the intake temperature must reach 523 K when the compression ratio is 18 for ammonia fuel to be compression ignited. At the same time, it was found that under this condition, ammonia fuel can burn under lean conditions (ϕ=0.2). The study also found that when the intake temperature is 523 K, the minimum-to-compression ratio during ammonia compression ignition decreases from 18 to 10 as the hydrogen doping ratio increases from 0 to 0.2.
Black-Box Modelling of Active Distribution Network Devices Based on Neural ODEs
Authors: Hu Ran , Ma Nan , Li Bing , Chen Kun , Chen Chen , Huang Zhanhua , Ye Fengshu , Pan Chunpeng
Published: August 2024

The morphological structure and dynamic characteristics of power distribution systems are rapidly evolving due to the widespread application of distributed renewable energy and the rapid advancement of power electronics technology. The stability analysis of these complex new distribution systems depends on electromagnetic transient (EMT) simulation. However, the intellectual property rights protection by manufacturers leads to many distribution network devices that can only use black-box models with missing parameters, which challenges the simulation. This reduces the accuracy of the dynamic analysis of these new distribution systems. To address this problem, this paper proposes a black-box modelling method based on neural Ordinary Differential Equation (ODE) for active distribution equipment. The method uses port measurement data to construct a data-driven model that accurately captures the black-box device characteristics, transforming the uncertainties in the user-side black-box devices into observable, controllable, and analysable models. The paper also builds an IEEE-33 node system that includes the energy storage black-box model for validation, and the results confirm the accuracy of the model.
Optimal regulation strategy of energy storage combined with new energy stations participating in power market
Authors: Chen Chunyi , Zhu Huangru , Huang Bonan , Guo Tai
Published: August 2024

Energy storage systems can efficiently address the challenges of inadequate power grid regulation capabilities and the escalating complexity of maintaining frequency stability due to a significant integration of renewable energy sources. Under the background of power marketization reform, it is highly important to establish a perfect power market mechanism and incorporate energy storage into it to stimulate energy storage advancements. Consequently, this paper proposes an optimization model for energy storage in conjunction with new energy stations participating in the power market, following the introduction of new energy storage technologies. It effectively verifies the optimization energy storage charge and discharge duration with examples. It achieves the realignment of output curves for coordinating the operation of new energy stations and energy storage facilities, enabling peak shaving and load shifting to minimize the peak-to-valley differential in the system load. It makes the overall output more ‘stable’ and improves the efficiency of the comprehensive operation of wind, solar, and energy storage. In the future, the engagement of energy storage will be essential in the market, and it is crucial to propose practical suggestions to enhance its participation.
Optimal configuration method of photovoltaic energy storage in distribution network based on source-load coordination
Authors: Chen Shuhao , Lin Fei , Zhao Xin , Li Heng
Published: August 2024

To enhance the configurability of photovoltaic energy storage within distribution network systems and foster synchronized development of power sources and loads, a source-load coordinated approach for optimal photovoltaic energy storage configuration in distribution networks is introduced. An alternative multi-objective framework for optimal allocation of photovoltaic energy storage capacity in distribution networks is formulated, which is the optimal goal of maximum economic benefit of photovoltaic energy storage, the optimal goal of minimum network loss and the optimal goal of source-network load coordination. The constraints of the system’s power flow, energy storage charging and discharging capabilities, and an optimized allocation strategy for energy storage are established, and the objective function is solved with full consideration of source-network load coordination factors. The energy storage optimization is updated in the iterative process. Based on the update results, the process for optimal allocation of photovoltaic energy storage in the distribution network has been devised to attain the most efficient allocation. Experimental results indicate a minimal discrepancy between the actual and specified energy storage output, along with a reduced average output power resulting from the optimized photovoltaic energy storage configuration, which shows excellent performance in energy storage optimization configuration.
Thermal optimization design of high-power charging station charging module
Authors: Zhang Siqian , Zhao Yingjie
Published: August 2024

When facing significant heat generation from a 30 kW high-power charging station, traditional air-cooling forced convection methods are insufficient to meet the cooling requirements. In this study, based on an in-depth analysis of power modules, we designed a key component of the liquid cooling system, the cold plate, through theoretical calculations. Using simulation techniques, we analyzed the temperature distribution within the cold plate and performed design optimization under conditions of a 4C charging rate and a thermal load of 1598 W. Considering the actual operating environment of the charging equipment, we selected a 50% volume fraction of ethylene glycol-water solution as the coolant and simulated its performance under extreme outdoor conditions of 50°C. Simulation results showed that the optimized liquid-cooled cold plate module achieved a junction temperature of 69.73°C, significantly lower compared to the initial temperature of 109.9°C, resulting in an approximately 36% improvement in heat dissipation efficiency. This significant enhancement not only highlights the advantages of the liquid cooling system in managing the thermal load of high-power charging stations but also addresses the issue of excessive heat load faced by traditional cooling methods. The outcomes of this research provide important theoretical and practical foundations for the thermal design of charging equipment, which is expected to play a critical role in improving the performance and reliability of charging stations.
Research on optimization strategy of grid carbon emission factor for promoting electricity-carbon market coupling
Authors: Zhao Fu , Fan Pengfei , Song Chongming , Li Ziqian
Published: August 2024

The grid emission factor is an essential parameter for accounting for carbon emissions caused by electricity consumption, and its update frequency and spatial accuracy affect the quality of the emission factor. Based on the existing regional grid emission factors, this study proposes an improved calculation method to get the revised emission factors. The revised emission factors can address barriers such as delayed updating, inequitable accounting between regions, and double measurement of green power emission reduction benefits. Therefore, the study can support the construction of the carbon market and the realization of carbon neutrality goals.
Stable and efficient all-inorganic quantum dot light-emitting diodes based on a double-layer electron transport layer
Authors: Shi Hengfei , Ren Zhenwei , Zhou Xin , Ji Huifeng , Zhang Yuze , Chen Yu
Published: August 2024

The most advanced quantum light-emitting diodes (QLEDs) have achieved almost unity external quantum efficiency (EQE) due to organic materials for high transport efficiency, but organic materials are less stable and can lead to irreversible degradation of the devices. The use of stable inorganic hole-transporting layers (HTLs), such as NiOx, becomes a promising alternative. ZnO is a common electron-transporting material in QLEDs, which possesses high mobility and tunable conductivity properties, but ZnO-based QLEDs devices undergo loss of efficiency due to exciton bursting, poor shelf stability, and pronounced positive aging effects. SnO2, as a common electron-transporting material, has better stability than ZnO. In this work, the SnO2/ZnO dual electron transport layer strategy is adopted, which can reduce the non-radiative burst and aging behavior, and at the same time, the electron transport is regulated by adjusting the film thickness. Inorganic QLEDs with high external quantum efficiency (9.5%) as well as high operational stability have been fully realized. This strategy provides effective ideas for future high-performance display devices.
Study on the degradation of welding strength in ceramic substrates subjected to temperature cycling
Authors: Yue Wenkai , Wang Xiaowei , Liu Yingxiao , Zhong Cheng , Jiang Binbin , Fang Xingce , Tang Zhixu
Published: August 2024

This article uses AlN and Al2O3 thick film substrates to conduct an in-depth study of the attenuation of welding strength of ceramic substrates under temperature cycling conditions. Using the test method of miniaturizing the substrate to test the transverse shear force, the shear force changes of different substrates with different 62Sn36Pb2Ag solder thicknesses were summarized and compared with the temperature cycle process. The finite element simulation method was used to simulate the Ag/SnPb interface, and the trend of interface stress and strain changing with temperature was obtained. Finally, the study found that during the temperature cycle, the Sn-enriched phase in the solder of the AlN substrate diffuses faster into the Ag layer, so the soldering strength of the AlN substrate decays faster during the temperature cycle.
Effect of bottom critical dimension (CD) size on TiN residual
Authors: Han Dingting , Jia Libin , Sun Hongbo , Li Weiran , Ren Huimin , Zhao Chao
Published: August 2024

The relationship between bottom critical dimension (CD) size and TiN residual in semiconductor manufacturing was elucidated. As an excellent electrode material, TiN needs to be cut from the continuous TiN film during the capacitor preparation process to achieve parallel connection of capacitors and increase capacitance. However, TiN film may only partially be removed under different process conditions. To illustrate the reason for TiN residual and its relationship with bottom CD size, the TiN and oxide thin films were deposited by atomic layer deposition (ALD) and plasma enhanced chemical vapor deposition (PECVD), respectively. The results show that the amount of TiN residual and bottom CD size was strongly coupled when the bottom CD size larger than 140 nm TiN can be fully removed. However, if the trench bottom CD size is smaller than 85 nm, there are different degrees (residual TiN thickness within the various of 1.8-11 nm) of TiN remain. Therefore, the results of this paper are of much importance as a reference for process design.
The influence of the hot-pressing process on the mechanical properties of continuous aramid fiber-reinforced PA12 composites
Authors: Yong Moxuan , Du Bing , Jiang Xibin
Published: August 2024

Hot-pressing post-treatment can effectively improve the mechanical properties of composite specimens. In order to improve the impact resistance of continuous aramid fiber-reinforced nylon 12 (CAF/PA12) composites, the effect of hot-pressing parameters on the interlaminar shear strength of the composite was studied. The effects of hot-pressing temperature, hot-pressing time, and hot-pressing pressure on the interlaminar shear strength of composite formed specimens were studied by single factor test. Based on the optimized parameters of hot-pressing, the influence of hot-pressing on low-speed impact performance was analyzed. The results shown that the interlaminar shear strength first increased and then decreased with the increase of hot-pressing temperature and pressure. With the extension of hot-pressing time, the interlaminar shear strength continued to increase. When the hot-pressing parameters were 170°C, 30 min, and 600 kPa, the shear strength and specimen quality were the best. Under this hot-pressing process, the low-speed impact performance was increased by 36.0%. In this paper, the research content of the hot-pressing process of composite materials was expanded, which provided a reference for the research of impact resistance of continuous aramid fiber-reinforced PA12 composite materials.
Effect of density and thickness on sound absorption performance of flexible porous material-aerogel
Authors: Dang Sizheng , Zhu Kailin , Yuan Zhaodong , Zhu Yuanzhi
Published: August 2024

Aerogel is recognized for its effective sound absorption capabilities, which contribute to its widespread application in reducing vibrations and noise. Consequently, it is often employed as a sound-absorbing material in various settings, including industrial machinery and the construction sector. In this research, we conducted an experimental analysis and employed standing wave tube testing to evaluate the sound absorption coefficient of aerogel. The investigation specifically focused on the impact of density and thickness on the sound absorption performance of aerogel. Through this process, we established the optimal structural parameters for aerogel to maximize its sound absorption efficiency. The study’s findings indicate that the sound absorption coefficient of aerogel sees a swift rise as its density increases from 0.4g/cm3 to 0.7g/cm3, with a subsequent deceleration in the rate of increase beyond the 0.7g/cm3 threshold. Concerning thickness, the sound absorption coefficient also experiences a rapid increase as the aerogel’s thickness is below 20mm, after which the rate of increase diminishes for thicknesses above 20mm. By considering both sound absorption performance and economic optimization, the research identifies a density of 0.7g/cm3 and a thickness of 20mm as the optimal parameters for achieving the best sound absorption with aerogel.
Research on channel-exposed carbon-based FET humidity sensor
Authors: Chen Qingqing , Zhang Yong
Published: August 2024

The ability to detect humidity is crucial for a variety of sectors, including industrial manufacturing, meteorological surveillance, and the preservation of materials, among others. Field effect transistor (FET) based sensor, renowned for its signal amplification effect, plays a pivotal role in detecting trace-level analytes with high sensitivity. Our work demonstrates the preparation of a humidity sensor based on carbon-based FET architecture, employing micro-nano processing techniques. In this work, semiconducting carbon nanotubes serve as the sensing material and channel at the same time. The outcomes indicate that the sensor exhibits a linear response ranging from 0% to 80% relative humidity (RH) and good repeatability. It also shows long-term stability in a 40-day test, proving potential applications in FET-type humidity sensors.
Deformation and stress analysis of frame and hub bearing based on FE simulation
Authors: Liu Hailong , Cao Shukun , Zhao Dong , Zhu Xiaoxuan , Zeng Li , Zhang Yihua
Published: August 2024

By using ANSYS Workbench, the deformation and stress of the frame and hub bearing were studied. For the deformation analysis of the frame, the maximum deformation of the original frame was 2.99 mm under no-load conditions, while the deformation of the improved frame was only 1.88 mm. By making a prototype of the frame and measuring the experimental deformation at the position of the radiator bracket under no-load conditions, it was found that the error between the test result and the simulation result was small, thus verifying the established FE model. Subsequently, the deformation of the frame was studied under full load conditions, and it was concluded that the maximum deformation was 2.47 mm, which was still less than the deformation of the original frame under no load conditions. For the FE simulation analysis of the double-row tapered roller hub bearing, compared with the inner ring, retainer, and outer ring, the equivalent stress of the tapered roller was up to 507.5 MPa, but it still didn’t exceed the yield strength, confirming the rationality of the designed bearing structure.
Thermal-fluid-structure coupling simulation of piston in large marine diesel engine
Authors: Luo Congcong , Zhao Minghang , Zhang Kai , Yu Xiaoxia , Li Junfu , Cui Zhiquan
Published: August 2024

Traditionally, most simulation approaches for pistons are conducted based on thermal-structure coupling, where the cooling boundary conditions are determined by empirical formulas. However, these approaches often suffer some decreases in the accuracy of the simulation results. Aiming at the problem, this paper conducts a thermal-fluid-structure coupling simulation method for the piston of a large marine diesel engine, which employs computational fluid dynamics to identify the cooling boundary conditions. Firstly, the solid and fluid models are established. Then, the cooling process of the piston chamber is simulated, with the temperature and heat transfer coefficients being mapped onto the solid component. Finally, loads and constraints are imposed on the solid component to accomplish the simulation. Under the presumed simulation conditions, the obtained coupling stresses are within the permissible range, with a maximum value of 419.68 MPa, and the dangerous region occurs at the junction of the piston head and the cooling chamber.
Research on thermal-solid coupling behavior of drum brake under emergency braking on slopes
Authors: Pan Yunping , Zhang Yuhua , Jin Zhengyi
Published: August 2024

When a truck makes emergency braking while driving on a slope, the transient impact force generated can easily cause personal injury to passengers and damage the vehicle’s braking system. In order to study the working state of the brake under this working condition, the ANSYS finite element thermal-solid coupling transient analysis method was used to establish the mechanical model and finite element model of the vehicle and brake under the slope emergency braking state, showing the temperature field and stress field distribution rules and interactions of the drum brake under this working condition, and compared with the flat road emergency braking condition. The results show that the maximum temperature of the brake reaches 184.26°C during emergency braking, and the stress field and temperature field are strongly coupled in two directions, which can easily lead to uneven wear of the linings and a reduction in the fatigue life of the brake.
Dynamic positioning system of ships with RBF neural network compensator
Authors: Zhao Ganyu , Yu Menghong
Published: August 2024

In Dynamic Positioning, traditional control methods lack stability, while neural networks and reinforcement learning have become research hotspots. By learning decision-making strategies from environmental observation data, we can adapt to environmental changes in real time and achieve optimal control effects. We also design a reward function to evaluate control performance. Dynamic inversion control is a control strategy that transforms nonlinear systems into linear systems. To address the issue of ship dynamic positioning, we propose a novel controller design method by combining RBF neural networks with dynamic inversion control. Its effectiveness has been verified through simulation experiments, demonstrating its potential and value in practical applications. This method will help improve the positioning accuracy of ships and optimize control performance.
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

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

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.