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, Volume 51 Issue 5 Previous Issue    Next Issue
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Research on the performance of plate and roll capacitor deionization devices based on supercapacitor carbon electrodes
Qihui WENG,Han CHEN,Sijia HE,Yi ZHANG,Yueping YANG
Journal of Zhejiang University (Science Edition), 2024, 51(5): 521-530.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.001
Abstract( 40 )   HTML( 3 )     PDF(4302KB)( 10 )

Capacitive deionization is an energy-saving and environmentally friendly brackish water desalination technology. The performance of capacitive deionization is influenced by two significant factors: electrode materials and device configurations. Three types of commercially available supercapacitor carbons AC1, AC2, and AC3 were used to characterize and optimize them for electrode production. The results demonstrate that AC2 activated carbon exhibits the highest specific surface area (1 908.4 m2·g-1) and specific capacitance (67.8 F·g-1). And AC2's internal pore resistance is also the lowest. Therefore, AC2 was chosen as the electrode material to study the operation of plate and roll devices under different experimental conditions. The optimal working voltage of the two configurations was 1.6 V, the temperature was 25 ℃, the optimal flow rate of the plate device was 60 mL·min-1, and for the roll device it was 360 mL·min-1. Under the optimal working conditions, the desalination amount per unit area and current efficiency of the roll device are 1 569.7 mg·m-2 and 46.7% respectively, much bigger than 696.5 mg·m-2 and 11.3% of the plate device. These results indicate that the roll device outperforms the plate device in terms of desalination performance and charge efficiency.

Research on the statistical monitoring and early warning of marine economy under the background of building a strong maritime power: Taking Zhejiang province as an example
Ying LAI,Peixiong CHEN,Zhiwen WANG,Zhiguang ZHOU,Weihua SU
Journal of Zhejiang University (Science Edition), 2024, 51(5): 531-541.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.002
Abstract( 26 )   HTML( 3 )     PDF(1982KB)( 24 )

As a quantitative manifestation of the development of the marine economy, the monitoring and statistical analysis of marine economic indicators is of great significance to the construction of a strong marine country. However, traditional systems for monitoring and statistical analysis of the marine economy are not perfect, and it is difficult to meet the coordinated land and maritime development and reflect the needs of decision-making. In this paper, we take Zhejiang province as a case study, where the strategic requirements of a strong marine country are integrated into the statistical monitoring and early warning analysis of the marine economy, innovatively improved the statistical classification system of the marine economy. "Nine core industries of the marine economy" classifications were setup, giving full play to the advantages of the marine industry. Based on this, a comprehensive early warning index for the core industries of the marine economy is designed in this paper and an early warning signal light is constructed to carry out early warning analysis on the core industries of the marine economy to meet the diverse needs of the strategic development of a strong marine province at multiple levels and with multiple objectives. The analysis based on marine economic statistical data, relevant policy recommendations are proposed, which can effectively implement the mission of building a strong marine province and providing decision-making support for relevant departments.

RLDEAO optimized of air quality data clustering analysis
Chuang TIAN,He HUANG,Lan YANG,Huifeng WANG,Feng RU
Journal of Zhejiang University (Science Edition), 2024, 51(5): 542-553.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.003
Abstract( 26 )   HTML( 1 )     PDF(4773KB)( 7 )

Aiming at the problems of high randomness, low clustering accuracy and multiple central points in clustering the same air quality data by traditional clustering methods due to different choice of initial points, a K-means complementary iterative air quality data clustering analysis method optimized by RLDEAO is proposed. Although aquila optimizer (AO) has a strong exploration ability, and its performance is not easily affected by different choice of initial points, it is easy to fall into local optimization. In view of this deficiency, we propose the adaptive dimension-by-dimension keyhole imaging reverse learning strategy, Levy flight combined with stagnation perturbation strategy and mutation evolution of the survival of the fittest to improve the search performance of the algorithm, thus avoiding local optimization; Secondly, a weighted maximum minimum distance product (WMMP) is designed to calculate the cluster center point, which can reflect the importance of each feature in the data and play a good role to improve the clustering results; Finally, RLDEAO and WMMP are combined to optimize K-means complementary iteration. Through clustering tests on multiple data sets, the convergence curves and evaluation indicators of the observed results show that the convergence accuracy and clustering effect of RLDEAO-KMC are better than AO-KMC, FCM, KMC and KMC++. It can be seen that RLDEAO-KMC can cluster information more efficiently and make better prediction and response.

Low power true phase clock flip-flop based on the conditional precharge technique
Maoqun YAO,Siyue QIU
Journal of Zhejiang University (Science Edition), 2024, 51(5): 554-561.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.004
Abstract( 22 )   HTML( 1 )     PDF(2321KB)( 5 )

Based on conditional precharge technology, a design method of high speed and low power real phase clock trigger is presented. This method controls the redundant precharge activity of internal nodes by adding field effectors and control conditions to the critical path with redundant switching activity. And by using the method of eliminating the redundant structure, it eliminates the redundant field effectors. This method improves the circuit structure and reduces the power dissipation and total power delay product. The simulation results of simulation program with integrated circuit emphasis, (HSPICE) show that the power dissipation of the proposed flip-flop is as low as 158.612 7 nW and the power delay product is as low as 0.048 735 fJ at 100 MHz operating frequency and low threshold voltage. The circuit has correct logic function and is superior to previous approaches in power dissipation and delay.

Mathematics and Computer Science
Anti-Ramsey numbers for three classes of special subgraphs in wheel graph
Zhongmei QIN,Yue SHEN,Fenjin LIU
Journal of Zhejiang University (Science Edition), 2024, 51(5): 562-567.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.005
Abstract( 31 )   HTML( 1 )     PDF(467KB)( 12 )

A subgraph in an edge-colored graph is called rainbow, if all its edges have different colors. Given two graphs G and H, the anti-Ramsey number for H in G, denoted by ar(G,H), is the maximum number of colors in an edge-coloring of G such that G contains no rainbow copy of H. In this paper, we determine the exact values of the anti-Ramsey numbers for Theta, star, double star graph when the host graph G is wheel graph.

Global regularity of generalized MHD-Boussinesq equations
Meihua DU
Journal of Zhejiang University (Science Edition), 2024, 51(5): 568-571.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.006
Abstract( 31 )   HTML( 0 )     PDF(435KB)( 13 )

The purpose of this paper is to study the global well-posedness of generalized MHD-Boussinesq equations with only velocity dissipation in whole space Rn (n2). Firstly, by exploiting the structure of this system, we obtain the uniform L2-bound of the global solutions. Then, the uniform H1-bound of the global solutions is proved by making use of logarithmic type interpolation inequality and the improved Gronwall inequality. Finally, by using delicate energy estimates, we overcome the difficulty of lack of dissipation and establish the a priori uniform Hss>1+n/2 estimate which proves the global existence and uniqueness of the classical solutions to this system.

The differences between global Roman domination number and Roman domination number in cubic graphs
Zhihong XIE,Yuqi WU,Guoliang HAO,Haining JIANG
Journal of Zhejiang University (Science Edition), 2024, 51(5): 572-579.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.007
Abstract( 28 )   HTML( 0 )     PDF(571KB)( 5 )

A Roman dominating function of a graph G is a function f from the vertex set V of G to the set {0,1,2} if the open neighbor of any vertex v of G with f (v)=0 has at least one vertex u with f (u)=2. If a function f is a Roman dominating function of a graph G and its complement, then f is called a global Roman dominating function of G. The uVf(u) is called the weight of a (global) Roman dominating function f of G. The (global) Roman domination number of G is the minimum weight of a (global) Roman dominating function of G. By analyzing the structure of graphs, according to the number of vertices of cubic graphs, the differences between global Roman domination number and Roman domination number are obtained.

A Hilbert-type inequality related to the higher derivative of cotangent function
Xiaochun SHI
Journal of Zhejiang University (Science Edition), 2024, 51(5): 580-585.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.008
Abstract( 27 )   HTML( 1 )     PDF(423KB)( 12 )

By introducing multiple parameters, and using partial fraction expansion of Cotangent function, a new Hilbert-type inequality defined in the whole plane with the constant factor related to the higher derivative of cotangent function is established. Also, the equivalent form of the inequality is considered. Furthermore, assigning different values to the parameters, some special Hilbert-type inequalities defined in the whole plane are obtained.

Sufficiently necessary conditions for the optimal matching parameters of super-homogeneous kernel integral operator in Lebesgue space with added exponential weight
Yong HONG
Journal of Zhejiang University (Science Edition), 2024, 51(5): 586-592.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.009
Abstract( 30 )   HTML( 2 )     PDF(428KB)( 15 )

The concept of super-homogeneous function is introduced, the homogeneous kernel, quasi-homogeneous kernel and many non-homogeneous kernel are united as super-homogeneous, as well as the boundedness problems of super-homogeneous kernel integral operator are discussed in the Lebesgue space of the added exponential weight, the sufficiently necessary conditions for the best matching parameters of bounded operators are obtained, and the problem of calculating the operator norm is solved. Finally some special cases are given as applications.

Strong NP-hardness of two-machine flow-shop scheduling with periodic due dates
Xiaolong CUI,Zhouli HE,Jiajie MEI,Long WAN
Journal of Zhejiang University (Science Edition), 2024, 51(5): 593-598.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.010
Abstract( 26 )   HTML( 0 )     PDF(530KB)( 7 )

we consider three two-machine flow-shop scheduling problems with periodic due dates, where each due date is assigned not to a specific job but to the processing order and the lengths of the intervals between two consecutive due dates are identical. The objectives are to minimize the maximum tardiness, the total tardiness and the total number of tardy jobs, respectively. In this paper, we show that all three problems are strongly NP-hard. Furthermore, our results also mean that if PNP, there is no pseudo polynomial-time algorithm and fully polynomial-time approximation scheme (FPTAS) to solve these problems.

A cross-efficiency aggregation method based on fairness perspective
Xingxian ZHANG,Wenjin ZUO,Yingming WANG,Panpan WANG,Renjie WANG
Journal of Zhejiang University (Science Edition), 2024, 51(5): 599-610.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.011
Abstract( 62 )   HTML( 0 )     PDF(1869KB)( 10 )

Aiming at the aggregation problem of cross-efficiency in data envelopment analysis (DEA), this paper proposes a new regret cross-efficiency aggregation method based on fairness perception. Firstly, the regret theory is introduced to describe decision-makers' regret aversion, and the regret-rejoice matrix is constructed. Secondly, the intersectional cross-efficiency model is used to calculate the perceived utility of regret fairness. Then, a cross-efficiency aggregated weight distribution model is constructed and the cross-efficiency of regret interval considering fairness perception is calculated. The lower and upper limits of cross-efficiency of regret interval are synthesized by introducing a parameter reflecting the psychological preference of decision-makers. Finally, an example is given to verify the validity and rationality of the proposed method.

Earth Science
Measurement and coordination analysis of land and sea ecological effects of "production-living-ecological" space in Zhejiang coastal zone
Yue QIAN,Guanmin QIAO,Yi ZHOU,Jingwu MA
Journal of Zhejiang University (Science Edition), 2024, 51(5): 611-622.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.012
Abstract( 37 )   HTML( 3 )     PDF(3615KB)( 21 )

Based on the content of the land and sea "production-living-ecological" space, we measure the ecological coordination efficiency of land and sea from 2000 to 2020 by using the land ecological environment quality index, the ocean ecological environment quality index and the coupling coordination model. The results show that: (1) The ecological quality of land and sea "production-living-ecological" space corresponds to the development pattern of territorial space planning. The main production and living space is distributed around the Hangzhou Bay industrial belt and the coastal industrial belt of Wenzhou-Taizhou, where the important ecological space located in the blue security belt in eastern Zhejiang. (2) The comprehensive ecological effects of land and sea have deteriorated, mainly due to the continuously decline of environmental quality during the progress of rapid urbanization. (3) The coupled coordination status of land and sea ecological quality tends to be optimized. Specially, there is a high degree of coordination in Hangzhou Bay, Xiangshan Bay, et al. in northeastern Zhejiang province, where the land and sea joint management is effective. By contrast the land and sea joint management of the bay area in southeastern Zhejiang province needs to be improved. Our study provides the characteristics of the ecological pattern of coastal zone in Zhejiang province, which shows high intensity development in the land as well as quality ecological protection and restoration in the marine space. The results show that the coupling and coordination mode of land and sea bay is land-driven. Therefore, to build a beautiful bay, we need further strengthening the regional ecological governance and the control of functional marine space.

Urban Science
Spatial heterogeneity of influential factors of urban housing prices based on multiscale geographically weighted regression models: A case study of the main urban area of Guilin city
Jiejie LI,Changsheng SUN,Chunying ZHANG,Xinqi HU
Journal of Zhejiang University (Science Edition), 2024, 51(5): 623-635.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.013
Abstract( 33 )   HTML( 4 )     PDF(4734KB)( 6 )

Based on second-hand housing prices data in Guilin city in October 2022, this paper investigates the spatial heterogeneity of factors influencing housing prices at different scales using the multi-scale geographically weighted regression (MGWR) model. The results indicate that: (1) Significant spatial autocorrelation is observed in housing prices in Guilin City, and the local spatial autocorrelation reveals a distinct clustering pattern characterized by predominant "high-high" and "low-low" clusters, with smaller occurrences of "high-low" and "low-high" clusters. (2) Compared to ordinary least squares (OLS) model and geographically weighted regression (GWR) model, MGWR model demonstrates higher coefficients of determination, enabling more accurate measurement of the scale and spatial variability of variable effects on housing prices. (3) The age of housing, education/medical and business facilities serve as global variables; greening rate, public transportation infrastructure, railway facilities, living amenities, and tourist attractions exhibit moderate levels of spatial heterogeneity; external transportation facilities display greater spatial heterogeneity, exerting significant and distinctly varied effects on housing prices within local areas. (4) The age of housing, living amenities, and tourist attractions negatively influence housing prices negatively; education/medical, and business facilities positively influence housing prices; while other variables exhibit varying inhibitory or appreciative effects on housing prices across different spatial locations.

Tourism
Does tourist generated content (TGC) boost tourist motivation better? Dual verification via ISM-DEMATEL approach and experimental study
Ruoyu ZHANG,Gaojun ZHANG,Jingyi JIANG,Long CHENG
Journal of Zhejiang University (Science Edition), 2024, 51(5): 636-650.   https://doi.org/10.3785/j.issn.1008-9497.2024.05.014
Abstract( 38 )   HTML( 3 )     PDF(2779KB)( 18 )

Among a plethora of destination marketing and traveler comparative studies, an integral theoretical supposition is that public information uploaded by travelers such as narratives and photographs possess greater potential to catalyze travel intention. However, this hypothesis remains unsubstaintiated through empirical research. To this end, this paper takes tourism photos as the starting point, adopts the idea of cross-examination to seek the stability of the research conclusions, constructs an index system of the influence of tourism photos on tourism willingness in three dimensions of "express" factors, "hints" factors and information quality, and introduces the ISM-DEMATEL method to construct an explanatory structure model. The robustness of the ISM-DEMATEL results are verified by experimental studies. Our study found that: Firstly, the hierarchical model of tourism photos affecting travel willingness has four levels, and the authenticity of information occupies the most significant position; Secondly, the level of typical characteristics of tourist generated content (TGC) is generally higher than that of official generated content (OGC), that is, in the process of stimulating people's willingness to travel, TGC are higher importance. Thirdly, the experimental results show that photos can significantly improve people's willingness to travel, which confirms that travel photos are a good destination marketing medium, and the promotion effect of TGC is the strongest among the three types, followed by the common feature of OGC and TGC, and finally the feature of OGC. At the theoretical level, this paper confirms the importance of TGC compared with OGC to tourism marketing, and consolidates the theoretical basis of related research; In practice, this paper argues that more focus should be attached on the quality of information in tourist photos and appropriately draw on the style of TGC to build a more attractive destination image.

14 articles