Search Results (20)

Photocatalytic H₂O₂ production with H₂O and O₂ as resources is a promising technique. Herein, a g-C₃N₄@CdS (CN@CdS) Z-scheme heterojunction is prepared for photocatalytic H₂O₂ production with a rate of 167.5 μmol/h, which is 5.43 and 5.15 times higher than that of pure g-C₃N₄ and pure CdS. Photoelectronic characterization results reveal the existence of a strong built-in electric field between CdS and g-C₃N₄, which significantly facilitates the separation of photogenerated carriers and preserves the strong redox capacity. Density functional theory (DFT) calculations show that CN@CdS displays lower O₂ adsorption energy and the H₂O₂ is more readily formed. This work provides a novel strategy for the design of photocatalysts with excellent H₂O₂ evolution efficiency. Full article

With the rapid development of digital networks and communication technologies, traditional word-of-mouth (WOM) has transformed into electronic word-of-mouth (eWOM), which plays a pivotal role in improving the management and service quality of ancient town tourism. This study uses Python web scraping techniques to gather eWOM data from the top ten ancient towns in southern China. Using IPA analysis, the analytic hierarchy process (AHP), Term Frequency–Inverse Document Frequency (TF-IDF), and cluster analysis, we developed a comprehensive eWOM evaluation framework. This framework was employed to perform word frequency analysis, sentiment analysis, topic modeling, and rating analysis, providing deeper insights into tourists’ perceptions. The results reveal several key findings: (1) Transportation infrastructure varies significantly across the towns. Heshun and Huangyao suffer from poor accessibility, while the remaining towns benefit from the developed transportation network of the Yangtze River Delta. (2) The volume of eWOM is strongly influenced by seasonal patterns and was notably impacted by the COVID-19 pandemic. (3) The majority of tourists express positive sentiments toward the ancient towns, with a focus on the available facilities. Their highest levels of satisfaction, however, are associated with the scenic landscapes. (4) A comprehensive eWOM analysis suggests that Wuzhen and Xidi–Hongcun are the most popular tourist destinations, while Zhujiajiao, Huangyao, Zhouzhuang, and Nanxun exhibit lower levels of both attention and visitor satisfaction. Full article

The detection of weak signals is a well-established application in chaos theory. This theory leverages the inherent robustness of chaotic systems, enabling them to resist noise and thus serve as effective tools for identifying weak signals. However, challenges remain in selecting appropriate chaotic systems and in their practical implementation—areas that are still under-explored. In this paper, we analyze a simplified fractional-order Genesio–Tesi chaotic system, which exhibits a unique chaos-divergence characteristic. Based on this characteristic, we propose a new detection method that uses the chaos-divergence state as a criterion for determining the presence or absence of a signal when detecting weak signal amplitudes. This approach makes the simplified fractional-order Genesio–Tesi chaotic system more suitable for chaotic weak signal detection. Notably, the significant variance observed in the divergent state’s independent variables emerges as a key feature, enhancing the system’s ability to detect the frequencies of weak signals. Our numerical simulations focus on detecting weak cosine signals masked by three different types of noise. The results demonstrate successful detection of a weak signal at a frequency of 100 rad/s under the specified conditions, with the lowest detectable signal-to-noise ratio of −40.83 dB. Overall, these results highlight the effectiveness and feasibility of our proposed method for weak signal detection. Full article

Although data-driven machine learning methods have been successfully applied to predict complex nonlinear dynamics, forecasting future evolution based on incomplete past information remains a significant challenge. This paper proposes a novel data-driven approach that leverages the dynamical relationships among variables. By integrating Non-Stationary Transformers with LightGBM, we construct a robust model where LightGBM builds a fitting function to capture and simulate the complex coupling relationships among variables in dynamically evolving chaotic systems. This approach enables the reconstruction of missing data, restoring sequence completeness and overcoming the limitations of existing chaotic time series prediction methods in handling missing data. We validate the proposed method by predicting the future evolution of variables with missing data in both dissipative and conservative chaotic systems. Experimental results demonstrate that the model maintains stability and effectiveness even with increasing missing rates, particularly in the range of 30% to 50%, where prediction errors remain relatively low. Furthermore, the feature importance extracted by the model aligns closely with the underlying dynamic characteristics of the chaotic system, enhancing the method’s interpretability and reliability. This research offers a practical and theoretically sound solution to the challenges of predicting chaotic systems with incomplete datasets. Full article

A single-photon avalanche diode (SPAD) is a photon-counting sensor renowned for its exceptional single-photon sensitivity. One significant feature of SPADs is their non-linear response to light, making them ideal for high-dynamic range imaging applications. In SPAD imaging, the photon detection mode, which depends on the quenching method employed, is crucial for optimizing image quality and dynamic range. This paper examines the free-running and gating imaging modes, evaluating their impacts on photon capture and saturation limits. Given that the number of incident photons follows a Poisson distribution, we introduce an innovative imaging-quenching model based on statistical mathematics. We designed and fabricated two SPAD imaging sensors using 180 nm CMOS technology. Image processing and evaluation were conducted using a mapping method. Our results show that in low-light conditions, the gating mode surpasses the free-running mode in the signal-to-noise ratio (SNR). However, the free-running mode exhibits a saturation limit of more than an order of magnitude higher than that of the gating mode, demonstrating its superior capability to handle a broader range of light intensities. This paper provides a thorough analysis of the differences between the two imaging methods, incorporating the theoretical mathematical model, circuit characteristics, and computed imaging quality. Full article

This work investigates a fractional-order multi-wing chaotic system for detecting weak signals. The influence of the order of fractional calculus on chaotic systems’ dynamical behavior is examined using phase diagrams, bifurcation diagrams, and SE complexity diagrams. Then, the principles and methods for determining the frequencies and amplitudes of weak signals are examined utilizing fractional-order multi-wing chaotic systems. The findings indicate that the lowest order at which this kind of fractional-order multi-wing chaotic system appears chaotic is $2.625$ at $a=4$, $b=8$, and $c=1$, and that this value decreases as the driving force increases. The four-wing and double-wing change dynamics phenomenon will manifest in a fractional-order chaotic system when the order exceeds the lowest order. This phenomenon can be utilized to detect weak signal amplitudes and frequencies because the system parameters control it. A detection array is built to determine the amplitude using the noise-resistant properties of both four-wing and double-wing chaotic states. Deep learning images are then used to identify the change in the array’s wing count, which can be used to determine the test signal’s amplitude. When frequencies detection is required, the MUSIC method estimates the frequencies using chaotic synchronization to transform the weak signal’s frequencies to the synchronization error’s frequencies. This solution adds to the contact between fractional-order calculus and chaos theory. It offers suggestions for practically implementing the chaotic weak signal detection theory in conjunction with deep learning. Full article

Historic urban landscape (HUL) are essential for preserving the cultural continuity of traditional Chinese villages. Utilizing heritage management approaches to manage historic urban landscapes has significant implications for innovating the governance of these villages. This study used traditional Southern Anhui villages as empirical case studies to determine the key heritage management principles of HUL governance. This underscores the public policy nature of urban heritage conservation and highlights the importance of balancing heritage conservation with sustainable development through the involvement of diverse stakeholders and interdisciplinary institutional instruments. This study examined the development history of heritage management in traditional villages in Southern Anhui, revealing the characteristics and challenges of four aspects: public participation, planning and guidance, legislation and regulation, and fiscal financing mechanisms. Furthermore, it proposed strategies for optimizing the heritage management mechanisms within the HUL framework. Full article

As an important new flame retardant, zinc stannate (ZS) shows wide application prospects due to its many advantages. However, the flame retardant mechanism of composites made with polymer combined with ZS is still unclear. In particular, there is a lack of molecular level description of the micro-scale flame retardant mechanism. The combustion mechanism through molecular simulation technology has become an important research paradigm in the field of fire, which can provide new insights for the development of new materials. This work studied the flame retardant mechanism of composites consistent with polypropylene (PP) and ZS using reactive force field molecular dynamics (ReaxFF MD) simulations. A new force field incorporating Sn/Zn/C/H/O components for ZS/PP composites combustion reactions was developed. Twenty different ZS/PP composites were analyzed for their combustion reactions at various temperatures. To investigate the flame retarding mechanism of ZS in composites, the evolutions of reactants, products, and reaction intermediates at the molecular scale were collected. It was revealed that the combustion temperature controlled the degree of oxidation by regulating the consumption of molecular oxygen during PP cracking. An increased combustion temperature reduced the oxygen consumption rate and overall oxygen consumption. As the PP component of composites exceeded 56%, oxygen consumption increased. Evolutions for carbon-containing intermediates and the products in combustions of PP/ZS composites were analyzed. The small carbon-based fragments were more likely to be produced for composites with low PP contents at high temperatures. These results are beneficial to design ZS/PP composites as flame retardant materials. Full article

In TiO₂-based perovskite solar cells (PSC), the preparation of the CH₃NH₃PbI₃/TiO₂ composite layer is very important, since the morphology of the perovskite adsorbed onto the surface of the TiO₂ nanoparticles has decisive significance for the absorption of the incident sunlight and separation of the generated carrier. The traditional two-step spin-coating method for the deposition of CH₃NH₃PbI₃ into the porous mesoporous TiO₂ layer usually suffers from filling block problems. In this study, the PbO-TiO₂ mesoporous layer was prepared with various ratios of Pb:Ti in the raw materials. Morphological, optical, and element analysis of the prepared thin films indicated that Pb was gradually mixed into the TiO₂ mesoporous layer with the increased Pb:Ti ratios. The element distribution characteristics of the optimal thin films showed that the distribution of Pb was uniform throughout the whole TiO₂ thin film, which indicates the successful mixing of Pb into the TiO₂ electrode layer. Combined with dip coating, the PbO-TiO₂ mesoporous layer was prepared into a CH₃NH₃PbI₃/TiO₂ composite layer and subsequently to a solar cell device. The prepared solar cell shows a short-circuit photocurrent density of 16.4 mA/cm², an open-circuit voltage of 900 mV, a fill factor of 61%, and a power conversion efficiency (PCE) of 9.00%. The PCE of the PSC is promoted by nearly 25% when compared with that prepared with the traditional method. The proposed preparation method that combines TiO₂ nanoparticle electrode with a mixing and dip coating provides a new effective way to improve the deposition of perovskite into the mesoporous TiO₂ layer, which is very helpful for the fabrication of high-efficiency and low-cost PSC. Full article

The sustainable development of traditional diets in the tourist industry is an important issue. This article analyses the historical evolution and the opportunities for a traditional Chinese dish in tourism. Taking mandarin fish in Anhui cuisine as the research object and the world heritage site Hongcun as the case, this paper investigates the evolution process of the local traditional die driven by tourism and its influence on the construction of gourmet tourism destinations. Primary data were obtained via interview. It was found that, to cater to the mass tourists, the destination created the diet frontstage. Traditional food changed through menu simplification, taste changes, the standardization and scale of production, and the immobilization of presentation. The dieter’s frontstage and backstage are not entirely separated; the “middle stage”—Homestay diet is a fusion of them; it is the product of functional differentiation of the frontstage and active integration of the backstage. By expressing the actual state behind the scenes, the middle stage transforms the tourist system from a “supportive experience” to a “peak experience”. Full article

This work presents first-principles calculations on the surface and defect impact upon zinc stannate (ZS) materials with perovskite bulk structures. The structure and electronic properties of both a perfect 001 surface and surfaces with a point defect of ZS were investigated by means of density functional theory calculations. The cohesive energies of a perfect 001 surface and those with O, Sn, or Zn defects were decreased compared with that of bulk ZS. Oxygen defects on the 001 surface of ZS formed more easily than others based on the obtained cohesive energy and defect formation energy. The electronic properties close to the Fermi levels of bulk ZS materials were mainly controlled by the O 2p and Sn 5s orbitals. The formation of vacancy on the 001 surface of ZS changed the band structure and band gap compared with that of the bulk. The modulation mechanism was explored by means of structure transformation, band structure, and density of states analysis. Full article

The contradiction between tourism development and sustainable heritage is a topic of academic debate. Taking Hongcun village, a UNESCO World Heritage site in China, as a case study, this paper focuses on the role of resident spatial practice and provides the possibility of balance between capital-driven and sustainable development and local culture, which has important implications for the sustainable development of cultural heritage. The study used archival research, non-participatory observations, and semi-structured interviews, following Pierre Bourdieu’s theory of practice to analyze the practical logic of local residents who transform their dwellings to achieve the aim of landscape sustainability. This study found that in the development of Hongcun tourism, the residential landscape has been adaptively transformed at both the material and non-material levels, due to residents’ habitus and the capital brought in by tourism. This material transformation was mainly manifested in the change of residential function, the courtyard structure, and the alienation of residential space. The non-material transformation was mainly manifested in the relationships between residents and other actors. Residents who tended to conduct protection actions positively were more likely to achieve a sustainable livelihood that contributes to a sustainable cultural landscape. This paper argues that the sustainable development of heritage requires that attention be paid to the positive role of grassroots agents and practices. Bottom-up agency is the key to realizing the adaptation of living heritage to external changes. Full article

As Chinese traditional villages are receiving increasing attention from the country, society and business in terms of sustainable tourism development, their residents’ perceptions have not been thoroughly investigated. To contribute to the literature, this qualitative study, which was based on stakeholder theory, conducted semi-structured in-depth interviews with 12 different stakeholders in Hongcun, one of the most well-known traditional villages in China. Using grounded theory approach, this study found that residents’ perceptions and attitudes of sustainable development differed in four main areas—economic, environmental, social, and cultural—and several sub-themes were developed to influence these four areas. The study results have important theoretical and practical implications for current sustainable tourism development in traditional villages. In particular, these results have substantial value for the country, society, and business levels with respect to developing traditional village sustainable tourism based on the perceptions and attitudes of the residents. Full article

Based on archival research, non-participatory observation, and semi-structured interviews, this paper examined waterway landscape changes mainly caused by tourism development in Hongcun, a traditional village in the Huizhou region, China, and how the locals have responded to water pollution in order to achieve landscape sustainability. It is found that the physical structure of the waterways of Hongcun Village has been well preserved, but the water pollution caused by tourism, with a combination of changes of land use and demographic structure, has changed the functions and cultural meanings of waterways. Although there remains quite a daunting task towards sustainability in terms of technology, heritage protection, and desire for development, we claim the waterways environmental governance in which local governments play a crucial role in resilience strategies by controlling the sewage from homestays, restaurants, and pigment sewage from sketches. However, the ways in which landscape animates, including the daily lives, processual daily practices, and mundane activities of different social actors related to waterways, deserve further implementation to build the resilience of cultural landscape from the perspective of non-representational theory. This paper adds to a new narrative to the waterway landscape research by presenting a water utilization pattern that could profitably coexist with a specific environment in the Huizhou region in the agricultural society of ancient China and discussing how the non-representational theory contributes to analyzing and managing waterway landscapes in modern times. It also sheds light on the connection between cultural landscape and resilience. Full article

Due to the more and more serious cyanobacteria bloom problem, it is particularly urgent to find a technology suitable for large-scale disposal and the efficient recovery of abundant nitrogen and phosphorus resources in cyanobacteria. The combination of chemical looping combustion (CLC) and biomass densification technology is thought to be a promising utilization selection. Based on the experimental results, the mechanical strength and energy density of briquette cyanobacteria are evidently increased with the compressive load; whereas, 10% is the optimal moisture content in the densification process. A higher heating rate in TGA would result in the damage of the internal structure of the briquette cyanobacteria, which are conducive to the carbon conversion efficiency. The presence of a hematite oxygen carrier would enhance the carbon conversion and catalyzed crack liquid products. CO₂ yield is increased 25 percent and CH₄ yield is decreased 50 percent at 900 °C in the CLC process. In addition, the lower temperature and reduction atmosphere in CLC would result in a lower NO emission concentration. The reactivity and porous property of hematite OC in CLC also increased during 10 redox cycle experiments. The CLC process accelerates the generation of CaH₂P₂O₇ and CaHPO₄ in cyanobacteria ash, which is more conducive to phosphorus recovery. Full article