bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic waves in gas-filled structured porous media: Asymptotic tortuosity/compliability and characteristic-lengths reevaluated to incorporate the influence of spatial dispersion
Authors: Lafarge D.
Published: December 2024

This study extends efforts to incorporate spatial dispersion into Biot-Allard’s theory, with a focus on poroelastic media with intricate microgeometries where spatial dispersion effects play a significant role. While preserving Biot’s small-scale quasi-“en-bloc” frame motion to keep the structure of Biot-Allard’s theory intact, the paper challenges Biot’s quasi-incompressibility of fluid motion at that scale by introducing structurations in the form of Helmholtz’s resonators. Consequently, Biot-Allard’s theory undergoes a significant augmentation, marked by the arising of non-local dynamic tortuosity and compliability, which are associated with potentially resonant fluid behavior. Building on an acoustic-electromagnetic analogy, the study defines these non-local responses and suggests simplifying them into pseudo-local ones, now potentially resonant and reminiscent of Veselago-type phenomena. In the high-frequency limit of small boundary layers and as an extension of the classical Johnson-Allard’s findings, simple field-averaged formulas are demonstrated for pseudo-local ideal-fluid tortuosity and compliability (complex frequency-dependent) and viscous and thermal characteristic lengths (positive frequency-dependent). These formulations are grounded in the Umov-Heaviside-Poynting thermodynamic macroscopic acoustic stress concept, suggested by the analogy. Future computational investigations, spanning various fundamental microgeometries, are planned to assess assumed pseudo-local simplifications, encompass low- and intermediate frequencies, and unveil potential behavioral outcomes resulting from the incorporation of spatial dispersion effects.
Filter-based first- and higher-order diffraction modeling for geometrical acoustics
Authors: Kirsch Christoph , Ewert Stephan D.
Published: December 2024

Geometrical acoustics (GA) offers a high computational efficiency, as required for real-time renderings of complex acoustic environments with applications in, e.g., hearing research, architectural planning, and entertainment. However, the assumed ray-like sound propagation does not account for perceptually relevant effects of diffraction. In indoor environments, diffraction at finite objects and apertures such as tables, music stands, and doors is of interest for computationally efficient rendering. Outdoors, buildings and barriers are relevant. Here, we extend the recent physically-based universal diffraction filter approximation (UDFA) for GA to approximate spectral effects of higher-order diffraction and apply it to a flat finite object and a double edge. At low frequencies, such effects predominantly occur when sound is diffracted repeatedly at the edges of a finite object, and at high frequencies when sound is propagating around subsequent edges of, e.g., buildings or sound barriers. In contrast to existing methods, the suggested filter approaches and topology offer spatially smooth infinite impulse response implementation for modelling higher-order diffraction at flat objects for arbitrary geometrical arrangements. For double diffraction at a three-sided barrier, errors are considerably decreased in comparison to a state-of-the-art sequential approach. Both suggested methods are computationally highly efficient and scalable depending on the desired accuracy.
French dentists' communication quality on clinical oral dermatology cases in Facebook groups: a cross-sectional study
Authors: Théry Mathilde , Bedez Maxime
Published: December 2024

Objectives: This study evaluates the communication quality of French dentists when sharing oral dermatology cases on Facebook. Material and methods: A cross-sectional analysis was conducted over six months, examining cases shared in both general dentistry and specialized oral dermatology groups. A custom scoring grid assessed the cases for relevancy and misinformation, focusing on general presentation, dermatological criteria, and diagnostic hypotheses. Results: A total of 242 cases were analyzed. The study found that the average number of missing communication criteria was 6.21 ± 2.01 points, indicating significant variation in the quality of case presentations. The specialized oral dermatology group demonstrated higher-quality communication, with an average of 5.80 ± 1.84 missing points, compared to 7.00 ± 2.09 in the general dentistry group. Conclusions: These results suggest that specialized social media groups offer enhanced opportunities for professional learning and more detailed case presentations. However, the study also highlights the challenges of ensuring quality and consistency in online case sharing. It emphasizes the need for standardized guidelines to improve the educational potential of social media platforms for professional development in oral dermatology. Improved practices and guidelines could help maximize the benefits of these platforms for dentists and other health professionals.
A study on Nike’s digital marketing strategy based on the 4Ps theory and analysis of competitiveness maintenance methods
Authors: Chen Tianxiang
Published: December 2024

This essay explores the concepts and theories of E-commerce, alongside the evolution and significance of digital marketing in the contemporary business landscape. It provides a comprehensive case study of Nike, focusing on its digital marketing strategies. Through Jerome McCarthy’s 4Ps of marketing—product, price, place, and promotion—the study offers a detailed analysis of Nike’s current brand positioning and placement strategies. The research includes a thorough review of existing literature and empirical studies, assessing Nike’s approaches and comparing them to those of its direct competitors, such as Adidas, as well as indirect and hidden competitors within the broader apparel industry. Key elements examined include Nike’s innovative digital campaigns, robust social media engagement, and interactive customer experiences. The study highlights how these strategies have enabled Nike to maintain its competitive edge and adapt to the fast-paced technological advancements in digital marketing. Additionally, the essay provides strategic recommendations for Nike to sustain and enhance its market position, emphasizing the importance of continuous innovation and adaptation in a rapidly evolving technological environment. The conclusion underscores that Nike’s cutting-edge digital marketing strategies have significantly contributed to its ongoing success and leadership in the sportswear industry, ensuring its relevance and appeal to modern consumers.
Research on the Impact of Blind Box on Consumers and Marketing Strategies
Authors: Zhan Haocheng
Published: December 2024

A blind box is a sales method where consumers purchase items without knowing the specific contents until after the transaction. This paper investigates the rapid growth of the blind box industry over the past few years and its impact on consumer behavior, particularly in the context of the market’s gradual decline in the post-pandemic era. As the initial excitement around blind boxes begins to fade, the study examines the strengths and weaknesses of this marketing strategy, uncovering issues such as the loss of trend appeal, chaos in the secondary market, and the excessive homogeneity of IP (Intellectual Property). By utilizing the addiction model, this research delves into the psychological factors that make blind boxes so compelling to consumers, leading to addictive purchasing behaviors. However, as the market matures, these marketing tactics have begun to reveal significant drawbacks. To address these challenges, the paper suggests several strategies: enhancing emotional design within blind box IP to foster deeper consumer connections, implementing stricter regulations on the secondary market, and actively exploring overseas markets to rejuvenate growth. These approaches aim to inject new life into the blind box industry, ensuring its sustainable development in the future.
Analysis of Nike and Adidas Marketing Strategies on TikTok
Authors: Ouyang Kaiwen
Published: December 2024

The sports industry, as an emerging force in China, contributes significantly to economic development and is closely linked to the booming development of the Internet and new media. TikTok, as a popular short-video platform, provides brands such as Nike and Adidas with a highly effective channel to interact directly with consumers thanks to its huge user traffic. Therefore, this paper uses the literature research method and case analysis method to analyze the marketing strategy of Nike and Adidas in TikTok operations. On this basis, it deeply explores the content selection and content creativity, and finally concludes. In terms of content strategy, both focus on graphic video promotion, with a smaller number of live broadcasts, and a focus on low-priced products. In terms of creativity, Nike and Adidas both utilize the challenge form on TikTok to strengthen the brand spirit and interaction. Nike’s “#JustDoIt Challenge” and Adidas’s celebrity virtual IP dance activities, both enhance brand exposure, which to a certain extent inspires users to participate in the creation and enhance the stickiness. Stickiness is to a certain extent to enhance the benefits of brand publicity. However, Nike’s interaction data on TikTok is significantly better than that of Adidas, showing stronger market appeal. Their successful marketing cases are highly valuable to study and learn from.
The impact of digital technology innovation on ESG performance: Evidence from A-share listed companies in China
Authors: Wu Yuanbang
Published: December 2024

The notion of Environment, Social and Governance (ESG) underscores the necessity for businesses to prioritize non-financial aspects such as environmental preservation, social accountability, and corporate governance while striving for economic advantages. The implementation and utilization of digital technologies have greatly enhanced the ESG performance of firms. This study investigates the influence of corporate digital technology innovation on corporate environmental, social, and governance (ESG) performance. The analysis is based on a sample of A-share listed businesses throughout the period from 2013 to 2022. The results demonstrate that the rise in the level of corporate digital technology innovation has a notable beneficial effect on ESG performance, particularly among companies that are not heavily reliant on technology. Furthermore, this increase is more readily apparent. Furthermore, the two-step method confirms that the implementation of corporate digital technology innovation can enhance ESG performance through optimization of operational efficiency and minimization of agency costs. Furthermore, the enhancement of ESG performance also exerts a positive influence on company performance and helps to alleviate financing limitations. The results of this study offer fresh insights and pragmatic recommendations for organizations to enhance sustainability during the digital transformation process.
Research on integration strategies and cultural adaptability of regional cuisines in China’s urban dining environments
Authors: Lyu Junfeng
Published: December 2024

This thesis explores how regional cuisines from various parts of China have successfully integrated into the dining markets of large cities amid urbanization, focusing on their adaptation mechanisms, market challenges, and future development trends. Firstly, through the study of successful cases in major cities such as Beijing, Shanghai, and Guangzhou, the thesis reveals how regional cuisine brands cater to the diverse needs of urban consumers through dish adjustments, restaurant atmosphere design, and brand promotion strategies. Secondly, it analyzes the challenges faced by regional cuisines in highly competitive and saturated urban environments, especially issues like homogenized competition and decreased brand differentiation. To address these challenges, regional cuisine restaurants seek to maintain competitiveness through dish innovation and health-oriented transformations. Finally, the thesis forecasts the future development trends of regional cuisines in urban dining markets, pointing out that health orientation, upscale positioning, digitalization, and policy support will become important drivers for the sustained development of regional cuisines. Through an in-depth analysis of these factors, this study provides a theoretical basis and practical reference for the continuous innovation and development of regional cuisines.
Navigating Challenges and Opportunities: A Comparative Study of Insurance Practitioners in China and Beyond
Authors: Lin Xiani
Published: December 2024

Since China’s reform and opening up in 1978, the Chinese economy has grown rapidly and has now become the world’s second-largest economy. With the transition from a planned economy to a market economy, Chinese households are facing greater market risks. This development has led to a continuous increase in the demand for financial security among Chinese residents, as well as the rapid growth of the insurance industry. However, although China has become the second largest insurance market since 2017, it still faces major challenges, including the lack of public trust and preparation in managing crises such as COVID-19. This study aims to identify the key factors affecting the development of insurance professionals in China by comparing the differences between insurance industries in different countries. From an international perspective, emphasize the existing gap in labor force in China’s insurance industry, and propose the best practices and innovative paths suitable for China’s national conditions. I hope these findings provide valuable insights for strengthening China’s insurance industry and enhancing its international competitiveness.
Current Situation and Development Trend of the New Energy Vehicle Industry in China
Authors: Pan Jiarui
Published: December 2024

In recent years, people have paid more and more attention to the importance of environmental protection and energy conservation, and new energy vehicles are favored by more and more people, and the car is gradually becoming one of the key products in the global automotive sector At present, the sales volume of new energy vehicles is growing continuously, and the trend of overall development is good. However, the industry is still facing many challenges, and there are still some deficiencies that need to be adjusted as soon as possible. This paper uses PEST analysis to conduct a comprehensive analysis of the internal and external current situation of the industry, and from the cost control, improve the follow-up infrastructure construction and strengthen the export of new energy vehicles in three directions, put forward specific and realistic suggestions on existing issues. Hope to provide a certain reference for the development of China’s new energy vehicle industry.
Analysis of Content Marketing Communication Strategy of the Internet Insurance Industry on the Xiaohongshu Platform
Authors: Mo Huiqi
Published: December 2024

With the development of Internet technology, the insurance industry has ushered in transformation and upgrading, the most prominent achievement of which is Internet insurance. Internet insurance has completely changed the traditional way of insurance sales. Currently, the content platform is the central position of Internet insurance marketing. Many Internet insurance companies carry out content marketing on the Xiaohongshu. Creating content attracts users to consult and then sell insurance products. Today, this Internet insurance sales model is quite mature. This paper uses the 5W theory, content analysis method, and case analysis method to analyze the communication strategy of Internet insurance on Xiaohongshu and finds that it adapts to the style of Xiaohongshu through young language, creating scenarios, and creating rich insurance content on the platform. However, there are areas for improvement, such as severe content homogenization and false advertising. In response to these issues, the author proposes optimization suggestions such as understanding user needs and regularly organizing training for content creators.
Impact of blockchain technology on supply chain collaboration: A case study of JD Chain
Authors: Chen Zhirui
Published: December 2024

This study uses JD.com as a case study to explore blockchain technology’s application in supply chain management. By leveraging distributed ledgers, consensus mechanisms, smart contracts, and cryptographic techniques, blockchain effectively tackles problems related to privacy protection, information traceability, and authenticity within traditional supply chains. This paper examines JD’s blockchain framework and its impact on various supply chain functions, revealing that blockchain technology has markedly improved procurement efficiency, reduced costs, enhanced customer trust and sales revenue, optimized logistics operations, and streamlined management processes. Through its JD Chain platform, JD.com has boosted operational performance and economic value and offered valuable insights for smaller enterprises. Given the technical and financial constraints faced by smaller firms, it is recommended that they engage in open source blockchain communities hosted by larger organizations to lower information acquisition costs and share resources. This paper provides practical advice for enterprises considering the integration of blockchain technology into their supply chain management.
Research on Profit Models and Financial Indicators of Social Video Platforms: A Case Study of Bilibili
Authors: Xu Tingyu
Published: December 2024

Bilibili, a secondary-dimensional online community video platform, attracts countless young people who are fans of the ACG culture circle with its unique secondary-dimensional elements, becoming one of the most popular social video platforms among the younger generation in China in recent years. Bilibili has its own unique business model and development potential, but facing the fierce competition among numerous video platforms in the market, the constant changes in user needs, and the continuous years of losses, how to increase revenue, reduce costs, and achieve profitability is currently an urgent problem that needs to be solved. This paper analyzes and studies the profit models of Bilibili’s mobile games, live streaming, value-added services, advertising, and intellectual property derivative products, and analyzes the financial indicators such as revenue, expenses, profits, debt repayment ability, profitability, and operational ability in recent years, points out the shortcomings that exist, and proposes suggestions for finding innovative income points and making selective investments to reduce expenses, which can provide reference for its sustainable development and improving its financial situation in the future.
Fintech’s Help to Rural Revitalization of commercial Banks-a Aase Study of Agricultural Bank of China
Authors: Huang Xin
Published: December 2024

The rapid development of global fintech has changed the traditional financial mode and accelerated the change of the traditional credit intermediary function of commercial banks. Fintech not only brings challenges to commercial banks but also provides new opportunities for commercial banks to develop new business models and innovative businesses and products. With the execution of the national rural revitalization strategy, all rural areas are leveraging their local natural resources to cultivate new industries; consequently, rural sectors continue to innovate and exhibit diversified development. Rural industries play a pivotal role in driving rural revitalization while simultaneously expanding financial demands within these communities. Finance is crucial for promoting regional economic development. At this critical juncture in advancing the “three rural issues,” commercial banks in China should assume their responsibilities by fully utilizing their advantages and increasing support for these areas. The research focuses on analyzing the Agricultural Bank of China as a case study to explore its application of financial technology and its impact on supporting rural revitalization efforts. It summarizes both the strengths and weaknesses of commercial banks in facilitating this process while offering optimization suggestions that can serve as reference points for other banks assisting farmers.
Research on the Evaluation of Beauty Market: From Traditional Media to Digital Platforms
Authors: Kang Jiaqi
Published: December 2024

The development of the internet allows digital social media platforms to increase their influence on daily life, and social media platforms also influence consumer behavior patterns. To cater to consumers, brands also need to make corresponding changes, but the direction of marketing and promotion to digital platforms does not mean that traditional media has been completely replaced. Social media is an opportunity as well as a change, and the advantages and risks coexist. Therefore, this study aims to explore the transition from traditional media to digital platforms, the synergistic effect between the two in the beauty market, and the impact on factors such as consumer purchase behavior. This study analyses the key findings of the past five years through a systematic literature review on factors such as the digital transformation of traditional media, the pros and cons of digital social media platforms, and their relationship to consumer purchasing behavior, and summarizes these studies. This study reveals the importance of using both digital social media and traditional media in the beauty market and suggests that brands should adopt multi-channel marketing strategies to reach a wider audience.
Exploring the Impact of Non-compliance Reduction by Major Shareholders on the Interests of Small and Medium-sized Shareholders
Authors: Chen Mingfei
Published: December 2024

In recent years, major shareholders have been able to trade in the secondary market to realize their shareholdings directly. However, this has also given major shareholders a new way to reduce their holdings, and major shareholders have frequently chaotically reduced their holdings. Despite the promulgation of relevant decrees by the Securities and Futures Commission (SFC), the behaviour of major shareholders in the process of reducing their shareholdings through securities market manipulation that infringes on the rights and interests of small and medium-sized shareholders to obtain excessive gains has not yet been curbed. In order to reduce the infringement of the rights and interests of small and medium-sized shareholders by large shareholders and to maintain the order of the capital market, this paper summarises the previous literature results in related fields and quantitatively and qualitatively analyses the current situation of major shareholders’ illegal shareholding reductions in light of the new regulations on illegal shareholding reductions that have just come into force in 2024. After that, the motivation and economic consequences of large shareholders’ illegal shareholding reductions are analyzed in depth. Finally, this paper proposes effective and feasible measures from the perspective of protecting the interests of small and medium-sized shareholders. This study gives a comprehensive understanding of the impact of large shareholders’ illegal shareholding reduction on small and medium-sized shareholders. It provides new perspectives and ideas for the protection of small and medium-sized shareholders’ interests to protect the stability of the market and investors’ rights and interests.
The Impact of Website Design: Composition, usability, and amount of information, on brand competitiveness and customer satisfaction in China
Authors: Yao Yutong
Published: December 2024

The COVID-19 pandemic has significantly reshaped China’s social and economic landscape, accelerating the shift toward e-commerce and prompting traditional retailers to establish online platforms. This transition has intensified competition among online stores, necessitating that merchants enhance customer trust and improve the overall shopping experience. This article examines effective strategies to optimize visual elements—such as web design and layout—to bolster consumer trust and increase purchase intentions. Through document analysis, it identifies prevalent challenges in the online shopping experience, including inaccurate information and poor interface design, assessing their detrimental effects on consumer behavior and overall store performance. The article also offers practical solutions aimed at addressing these issues, such as enhancing logo visibility, refining design and color schemes, ensuring accurate and diverse product information, implementing AI-driven shopping guides, and tailoring web design to specific target demographics. These strategies ultimately aim to enhance the market competitiveness of online retailers in an increasingly crowded marketplace.
Research on the Exchange Losses of Multinational Corporations
Authors: Yuan Mengyao
Published: December 2024

In the wave of global trade and investment, foreign currency transactions are increasingly frequent, and the risk of currency mismatch is prominent. Academia and industry are deeply studying its impact on the accounting conservatism of enterprises, and seeking to effectively manage this risk through financial derivatives and other means. This paper proposes a solution to introduce a third-party financial platform as an intermediary bridge on the basis of cross-currency interest rate swaps. The proposed model aims to significantly broaden the scope of CCIRS applications, making it easy for more multinational companies to use this financial tool to manage their exposure to exchange rate and interest rate risks. Looking ahead, with the deepening of global economic integration, the exchange rate and interest rate risks faced by multinational enterprises will become increasingly complex and volatile. The cross-currency interest rate swap model based on third-party financial platforms proposed in this paper is expected to provide a practical and efficient risk management tool for many multinational enterprises, help them move forward steadily in the global market, and contribute to the in-depth development of economic globalization.
Research on Mergers and Acquisitions and Development Trends in the Pharmaceutical Industry of State-owned Enterprises
Authors: Tu Lilyu
Published: December 2024

In recent years, Chinese state-owned enterprises have been continuously acquiring medical industry companies, aiming to improve the quality and efficiency of medical services through resource integration and technological innovation, and meet the growing health needs of the people. Therefore, this paper mainly aims to explore the results of Mergers and Acquisitions (M&A) of companies in the pharmaceutical area. It studies the characteristics and the effects of M&A of CR Pharma, Sinopharm, and Genertec. It finds out that they are a success, which reflects the motivation and strategic intention behind it. Their profits have continued to rise after M&A in general in recent years. In conclusion, consolidation has sparked several revolutionary developments that have improved market positioning, realigned strategy, and increased financial performance. Despite ongoing difficulties, these companies’ proactive effort to resolve these problems points to a bright future in the fast-paced pharmaceutical industry. The trend of M&A will continue, and the direction of M&A will also be adjusted according to the pace of economic development.
The Impact and Prospect of China’s Low Interest Rates on the Economy
Authors: Fu Jiarui
Published: December 2024

This article explores the impact of China’s long-term low-interest-rate policy on its economy and its future development direction. While the low-interest-rate policy has stimulated investment and consumption, it has also led to risks such as rising asset prices, real estate market bubbles, and increasing debt levels. The squeeze on bank profit margins may affect the stability of the financial system. The article reviews the development of China’s interest rate policy since 1949, analyzes the impact of low interest rates on consumption and investment, and predicts the trend of future interest rate changes. The study shows that a decrease in deposit interest rates may reduce the willingness to save, and increase consumption and investment, but may also increase market volatility and investment risks. Changes in the global economic environment and the need for domestic economic structural adjustment make it particularly important to study the impact of low interest rates on China’s future economic development.
Pain in Children and Adolescents with Cerebral Palsy: A Cross-sectional Survey Study
Authors: Bischoff Lena A. , Tscherter Anne , Hunziker Sandra , Grunt Sebastian , Graf Nicole T. , Künzle Christoph T. , Broser Philip J.
Published: December 2024

Aim This study aims to investigate the prevalence, intensity, and location of pain in children and adolescents with cerebral palsy (CP) and analyze pain-related symptoms and participation restrictions.

Methods Children and adolescents aged 2 to 16 years diagnosed with CP were invited to participate in a pain survey. The questionnaire was based on the German Pain Questionnaire for Children, Adolescents and Parents (DSF-KJ). It was administered to children (2–11 years) by their caregivers, while adolescents (12–16 years) were asked to complete the questionnaire themselves or with the help of their caregivers.

Results Fifty-seven of 133 children and adolescents with CP (43%) reported having pain in the past 12 months, of whom 17 (30%) reported chronic pain. Patients with Gross Motor Function Classification System (GMFCS) IV–V reported more frequent pain (p = 0.003) and higher pain intensity (p = 0.011). Lower extremity pain was the most common. Twenty-three percent of participants with pain did not receive any treatment. Pain often restricted participation, specifically by reducing sports activity in patients with GMFCS I–III, focusing attention on patients with GMFCS IV–V, and activities with the family in both GMFCS level categories.

Interpretation Pain is common in children and adolescents with CP and frequently restricts their participation. Therefore, it must be consistently recorded and addressed during the consultation. The goal of treatment should be not only to reduce pain but above all to increase participation.
The impact of P-type doping level and profile on performance of InAs quantum dot lasers
Authors: Liu Ruo-Tao , Du An-Tian , Cao Chun-Fang , Yang Jin , Wu Jian-Chu , Wang Kun , Yang Chen , Huang Hua , Gong Qian
Published: December 2024

The impact of P-type doping level on InAs quantum dot (QD) lasers grown on GaAs (001) was investigated through the device performance characterization, i.e., measurements of threshold current, output slope efficiency, and temperature characteristics of lasers. The lasers are characterized under continuous wave operation with a ridge waveguide of 6 × 4000 μm2. In comparison to un-doped lasers, it has been demonstrated that an appropriate P-type doping level in the entire spacer can reduce the threshold current density of lasers from 215 to 86.8 A/cm2 for a doping concentration of 10 holes per QD at room temperature. Additionally, an improvement in output power slope efficiency from 0.108 to 0.191 W/A has been obtained, along with an enhanced characteristic temperature from 34.4 to 67.5 K (20–100 °C). Moreover, modulation doping has been explored to further reduce the threshold current density down to 77.9 A/cm2 at room -temperature and raise the output power, while entire spacer doping may enhance device performance at high operating temperatures. By optimization of P-type doping, remarkable enhancements in the performance of QD lasers can be achieved, which might have potential applications in cost-effective high-performance photonic integrated circuits.
Influence of hydrostatic pressure on the characteristics of single-pulse discharge plasma in water
Authors: Lan Sheng , Yao Longhui , Ding Xiaoting , Wang Jiaxu , Wang Jianan , Yuan Yongbin
Published: December 2024

Liquid-phase plasma is widely used in industry, so it is important to study its characteristics. In this paper, an experimental system utilizing a cylindrical pressure tank with adjustable hydrostatic pressure for studying liquid-phase pulsed discharge plasma is designed, and the components and experimental principles of the system are introduced in detail. Based on this experimental system, the influence of hydrostatic pressure on the characteristics of liquid-phase plasma was investigated under varying voltage levels and electrode spacings. The results demonstrate that the experimental system can effectively generate and observe liquid-phase plasma. As hydrostatic pressure increases, the pre-breakdown delay at 15 kV and a 2 mm electrode gap increases from 25.6 μs at 0.1 MPa to 447.2μs at 0.5 MPa, while the duration of the main discharge stage decreases from 224.4 to 210.4μs. At 13 kV with a 2 mm electrode gap, the emission spectrum intensity and the electron density of the discharge plasma decrease with increasing hydrostatic pressure. The electron temperature in the plasma channel ranges from 11,000 K to 16,500 K. In addition, the discharge process phenomena were analyzed using typical high-speed camera images, highlighting the characteristics of the discharge plasma at each stage. Finally, the shortcomings and improvement of the experimental system are analyzed.
Circumventing traps in analog quantum machine learning algorithms through co-design
Authors: Bravo Rodrigo Araiza , Ponce Jorge Garcia , Hu Hong-Ye , Yelin Susanne F.
Published: December 2024

Quantum machine learning algorithms promise to deliver near-term, applicable quantum computation on noisy, intermediate-scale systems. While most of these algorithms leverage quantum circuits for generic applications, a recent set of proposals, called analog quantum machine learning (AQML) algorithms, breaks away from circuit-based abstractions and favors leveraging the natural dynamics of quantum systems for computation, promising to be noise-resilient and suited for specific applications such as quantum simulation. Recent AQML studies have called for determining best ansatz selection practices and whether AQML algorithms have trap-free landscapes based on theory from quantum optimal control (QOC). We address this call by systematically studying AQML landscapes on two models: those admitting black-boxed expressivity and those tailored to simulating a specific unitary evolution. Numerically, the first kind exhibits local traps in their landscapes, while the second kind is trap-free. However, both kinds violate QOC theory’s key assumptions for guaranteeing trap-free landscapes. We propose a methodology to co-design AQML algorithms for unitary evolution simulation using the ansatz’s Magnus expansion. Our methodology guarantees the algorithm has an amenable dynamical Lie algebra with independently tunable terms. We show favorable convergence in simulating dynamics with applications to metrology and quantum chemistry. We conclude that such co-design is necessary to ensure the applicability of AQML algorithms.
Research on Helmholtz self-excited oscillating jets enhanced heat transfer in horizontal tubes
Authors: Hou Wenjiang , Ou Jin , Chen Yan , Guo Xiaofeng , Fang Zhenlong , Fan Shidong
Published: December 2024

The self-excited oscillating jets have several advantages, including simple structures, environmental friendliness, and high efficiency. It has become a prominent research focus in the heat transfer field. This study focuses on analyzing the influence of the self-excited oscillation chamber structural parameters on the interaction between coherent structures and heat transfer. Combining the heat transfer enhancement of the pulsating backflow vortex with boundary layer theory, a self-excited oscillation horizontal tube model is constructed. The Large Eddy Simulation (LES) method simulates the self-excited oscillation in horizontal tubes. The heat transfer and flow resistance mechanisms in the tube are investigated. The results indicate that backflow vortices in the downstream pipe alternate near the shear layer. As the flow approaches the oscillator outlet, discrete vortices decrease, the pulsation effect weakens, the temperature gradient diminishes in the tube, and the heat transfer boundary layer thickens. The pressure drops and resistance coefficient in the horizontal tubes exhibit periodic pulsations. The optimal structural parameters of the Helmholtz horizontal tubes are obtained through comprehensive analysis: diameter ratio of the chamber to the upstream pipe DT/d1 = 9.5, ratio of the chamber length to the upstream pipe diameter LT/d1 = 4.3, collision wall angle α = 100°. The relationship between the structural parameters of the oscillator and the heat transfer factors has been established, guiding the application of the Helmholtz oscillating jets in the field of enhanced heat transfer.
A novel boundary constrained reconstruction method for unstructured finite volume method of Euler equations
Authors: Su Hongxing , Chen Zedong , Wei Yanxin , Chang Siyuan , Liu Jun
Published: December 2024

For the second-order cell-centered unstructured finite volume method, the variables are linearly distributed inside the grid cell. Classical methods use a first-order extrapolation process in calculating the boundary values, which can lead to loss of second-order accuracy at the boundary. In order to solve the problem, a novel boundary constrained reconstruction method is proposed for boundary values in the unstructured finite volume method. This method first solves for all cell-centered gradients using the weighted least squares method. Subsequently, the boundary cell center gradient is used to reconstruct the boundary face center values. These reconstructed boundary values, corrected by boundary conditions, are then added to the boundary cell gradient calculation stencils to recalculate the boundary cell center gradient. The above-mentioned steps are repeated iteratively, stopping when the boundary face center values stabilize. Numerical case validation shows that this method is able to ensure linear distribution of variables within the boundary cells of the second-order cell-centered unstructured finite volume method, thereby recovering the accuracy of boundary cell calculations.
Temperature inversion across coexisting phases in two-dimensional driven granular materials
Authors: Gao Guoxian , Chen Yanpei , Xu Ji , Li Kai , Lu Bona
Published: December 2024

A kinetic temperature difference across coexisting phases is a key feature of the non-equilibrium dynamics observed in granular systems. The evolution of the temperature ratio between the dilute and dense phases across the phase diagram is examined. Building on previous experimental results and recent simulation findings, we report a bimodal distribution of the bond-orientation order parameter in quasi-two-dimensional driven granular materials. Using the trough of P(Ψ6), we categorize particles into two distinct phases and analyze the temperature ratio between them across the phase diagram. Our findings reveal that the order parameter, kinetic energy, and temperature between the dense and dilute phases exhibit nonlinear growth in the density-amplitude phase space. Remarkably, the granular temperature ratio between these phases can either exceed or fall below unity, depending on the specific conditions, similar to phenomena observed in self-propelled particle systems. This behavior is driven by correlated motion with the boundary. Our study thus establishes a direct link between structural order and kinetic motion during phase transitions processes in granular materials.
Dynamics of droplet impact on a rotating surface with different contact angles
Authors: Mohsen Abrar A. A. , Song Yuxin , Tang Chenglong , Huang Zuohua
Published: December 2024

The dynamic characteristics of the droplets impacting a smooth stainless-steel rotating surface with different Weber numbers (We) have been studied. Liquids with various surface tensions and static contact angles (ethanol, 50%, 25%, and 20% ethanol solutions, and water) have been investigated. The result reveals that the increase in both the rotational speed (ω) and We is accompanied by the droplet spreading enhancement and the droplet distortion time reduction. Ethanol (with the lowest static contact angle) shows higher βmax than other studied liquids. Moreover, clear spreading and receding behaviors can be noticed for water droplets impacting a rotating surface, which are contingent upon the physical characteristics of the droplet, the surface structure, and external force. However, the receding behavior is not observed for ethanol and various ethanol solutions during the impingement process. The range of 20%–25% volume concentration of ethanol solution is considered critical, where the outer rims of droplets distort quickly after the spreading stage, and the droplet receding phenomenon starts diminishing. A receding regime is absent due to several factors, such as contact angle, low surface tension, viscous dissipation, etc. The curve-fitting and constant values of empirical models of Ds(t)Ds.max and βmax are re-estimated to reduce the error and fit the experimental data, as well as an empirical receding model for water (Dr(t)Ds.max) is estimated.
Hidden field discovery of turbulent flow over porous media using physics-informed neural networks
Authors: Jang Seohee , Jadidi Mohammad , Mahmoudi Yasser
Published: December 2024

This study utilizes physics-informed neural networks (PINNs) to analyze turbulent flow passing over fluid-saturated porous media. The fluid dynamics in this configuration encompass complex features, including leakage, channeling, and pulsation at the pore-scale, which pose challenges for detailed flow characterization using conventional modeling and experimental approaches. Our PINN model integrates (i) implementation of domain decomposition in regions exhibiting abrupt flow changes, (ii) parameterization of the Reynolds number in the PINN model, and (iii) Reynolds Averaged Navier–Stokes (RANS) k−ε turbulence model within the PINN framework. The domain decomposition method, distinguishing between non-porous and porous regions, enables turbulent flow reconstruction with a reduced training dataset dependency. Furthermore, Reynolds number parameterization in the PINN model facilitates the inference of hidden first and second-order statistics flow fields. The developed PINN approach tackles both the reconstruction of turbulent flow fields (forward problem) and the prediction of hidden turbulent flow fields (inverse problem). For training the PINN algorithm, computational fluid dynamics (CFD) data based on the RANS approach are deployed. The findings indicate that the parameterized domain-decomposed PINN model can accurately predict flow fields while requiring fewer internal training datasets. For the forward problem, when compared to the CFD results, the relative L2 norm errors in PINN predictions for streamwise velocity and turbulent kinetic energy are 5.44% and 18.90%, respectively. For the inverse problem, the predicted velocity magnitudes at the hidden low and high Reynolds numbers in the shear layer region show absolute relative differences of 8.55% and 4.39% compared to the CFD results, respectively.
Vortex dynamics of turbulent energy cascades
Authors: Almoguera Adrian Parrado , Kivotides Demosthenes
Published: December 2024

Employing vortex dynamics, we explore the turbulent cascade mechanisms in Schroedinger and Navier–Stokes fluids. While both cascades are driven by vortex instabilities, the ability of Navier–Stokes vortices to stretch and exhibit complex core dynamics significantly affects the resulting turbulence behavior. In dilute Schroedinger turbulence at scales smaller than the intervortex distance, Aarts-de Waele instabilities trigger reconnection-driven Kelvin wave energy cascades, transferring energy from the reconnection scale to smaller scales. At sufficiently long times, these cascades create a high-wavenumber bottleneck before transitioning into a k−5/3 local-interaction cascade scaling regime. Energy accumulates in the length scales preceding the bottleneck, triggering partial spectrum equilibration and resulting in a positive scaling exponent there, which differs from the equilibrium value of k2. At scales larger than the intervortex distance, the spectrum scales as k2, which is indicative of finite linear impulse in the system. In Navier–Stokes turbulence, the self-stretching of large-core vortices triggers an energy cascade to smaller scales, which is then intensified by the stretching of emergent vortex structures created by Crow or helical vortex line instabilities. The k−5/3 scaling arises only once this iterative process has progressed sufficiently to confine flow enstrophy within tubular regions, where the core size becomes a sufficiently small fraction of the overall system size. This confinement causes the vortices to appear quasi-singular when measured on large-scale units. The scaling of the entire-system spectrum is determined by the spectrum of the quasi-singular structures at the culmination of the cascade process, rather than by the cascade process itself.
Cavitation characteristics in rectangular flow restriction microchannel seals
Authors: Meng Weijun , Li Xiaobin , Su Wentao
Published: December 2024

The shaft seal of the primary pump relies on microchannel flow to prevent coolant leakage, but cavitation increases resistance, reduces efficiency, and damages equipment, affecting safety. Therefore, studying microchannel cavitation is crucial for optimizing seal performance and equipment reliability. This study explores the cavitation flow characteristics within a 0.1 mm rectangular flow restriction microchannel seal through experimental methods and numerical simulations. First, using a microfluidic experimental platform and visualization techniques, we directly observed the cavitation phenomena in the microchannel and quantified the evolution of cavitation bubbles under different conditions. Second, by establishing a numerical model of the microchannel, we analyzed the formation mechanisms of cavitation and its impact on flow characteristics under various conditions. The results show that lower cavitation numbers significantly increase the length of cavitation jets and the distribution range of cavitation bubbles, intensifying the cavitation phenomena within the microchannel. Additionally, microchannels with closely spaced double flow restriction structures are more effective at inhibiting cavitation than channels with a single flow restriction structure. These findings offer valuable insights into the mechanisms of microchannel cavitation and provide scientific guidance for the design and optimization of shaft seals.