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Study on filter soft partially ordered semigroups
Haiqin SHAO,Maolin LIANG,Jianwei HE
Journal of Zhejiang University (Science Edition)    2023, 50 (5): 521-526.   DOI: 10.3785/j.issn.1008-9497.2023.05.001
Abstract   HTML PDF (405KB) ( 473 )  

In this paper, we apply the theory of soft sets to partially ordered semigroup. First, several new notions such as left (right) filter soft partially ordered semigroup, filter soft partially ordered semigroup, whole left (right) filter soft partially ordered semigroup, whole filter soft partially ordered semigroup, prime left (right) ideal soft partially ordered semigroup, prime ideal soft partially ordered semigroup over partially ordered semigroups S are introduced. Further, with prime left (right) ideal soft partially ordered semigroup and prime ideal soft partially ordered semigroup over S, the necessary and sufficient conditions that the non-null soft set over S is a right (left) filter soft partially ordered semigroup and filter soft partially ordered semigroup over S are given separately. Finally, quotient ordered homomorphic images and inverse images under partially ordered homomorphic on left (right) filter soft partially ordered semigroup, filter soft partially ordered semigroup, whole left (right) filter soft partially ordered semigroup and whole filter soft partially ordered semigroup are studied,and some related conclusions are obtained.

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A review of conditional image generation based on diffusion models
Zerun LIU,Yufei YIN,Wenhao XUE,Rui GUO,Lechao CHENG
Journal of Zhejiang University (Science Edition)    2023, 50 (6): 651-667.   DOI: 10.3785/j.issn.1008-9497.2023.06.001
Abstract   HTML PDF (2011KB) ( 366 )  

Artificial intelligence generated content (AIGC) has received significant attention at present. As the numerous generative models proposed, the emerging diffusion model has attracted extensive attention due to its highly interpretable mathematical properties and the ability to generate high-quality and diverse results. Nowadays, diffusion models have achieved remarkable results in the field of condition-guided image generation. This achievement promotes the development of diffusion models in other conditional tasks and has various applications in areas such as movies, games, paintings, and virtual reality. For instance, the diffusion model can generate high-resolution images in text-guided image generation tasks while ensuring the quality of the generated images. In this paper, we first introduce the definition and background of diffusion models. Then, we present a review of the development history and latest progress of conditional image generation based on diffusion models. Finally, we conclude this survey with discussions on challenges and future research directions of diffusion models.

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Fuzzy implication algebras and its ideals theory
Chunhui LIU
Journal of Zhejiang University (Science Edition)    2023, 50 (4): 391-401.   DOI: 10.3785/j.issn.1008-9497.2023.04.001
Abstract   HTML PDF (1132KB) ( 349 )  

Algebraic analysis of fuzzy logic is one of the hot issues in the field of fuzzy logic research. In this paper, Fuzzy implication algebras and its ideals problem are further studied by using the method and principle of algebra and lattice theory. Firstly, some new properties of Fuzzy implication algebras are revealed by using pseudo-complement operators. Secondly, the concepts of ideal and generating ideal are introduced in Fuzzy implication algebras, and their properties and equivalent characterizations are investigated. Finally, the lattice theory characteristics of the set consisting of all ideals in a given Fuzzy implication algebra are discussed, it is proved that the set forms a distributive continuous (algebraic) lattice with respect to the set-inclusion order, in particular, it forms a complete Heyting algebra, and then forms a Frame.

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Hopf bifurcation of a food chain model with cooperative hunting
Wanqin HAN, Yao SHI, Xiongxiong BAO
Journal of Zhejiang University (Science Edition)    2023, 50 (5): 539-550.   DOI: 10.3785/j.issn.1008-9497.2023.05.004
Abstract   HTML PDF (3753KB) ( 220 )  

In order to study the impact of cooperative behaviors between predators on the dynamic behavior of the food chain system, a top-level predator (which only feeds on the predator population) on the basis of the original cooperative hunting model is introduced, and a food chain model with cooperative hunting is established. The local stability of the equilibrium point is discussed by using the linearization method. By establishing an appropriate Lyapunov function, a sufficient condition for the global stability of the system at the equilibrium point is given. In addition, by using the central manifold reduction theorem, the explicit formulas of the branch periodic solution is studied. Numerical simulations are conducted to verify our theoretical analysis. The results show that when there is no cooperative relationship between predators, the positive equilibrium point is stable. With the increase of cooperative predation parameter α, the system will have a stable limit cycle, and the limit cycle will continue to expand following the increase of cooperative predation parameter α. Moreover, if the predator population density is too large, the system will produce continuous periodic oscillation, that is, the three species i.e. diet, mid-level predator, top-level predator, either coexist in the form of periodic oscillation, or the number of species eventually tends to be stable. Therefore, cooperative hunting is more conducive to maintaining ecological balance.

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Approximation properties of q-type Lupas-Kantorovich operators
Tao WANG,Yan LI
Journal of Zhejiang University (Science Edition)    2023, 50 (5): 533-538.   DOI: 10.3785/j.issn.1008-9497.2023.05.003
Abstract   HTML PDF (420KB) ( 216 )  

We construct a q-type Lupas-Kantorovich operators based on the q-type integer and q-type calculus, investigate the rate of convergence of q-type Lupas-Kantorovich operators by modulus continuity as well as the properties of statistical convergence and weighted statistical convergence of the operators.

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Reconstructing tooth meshes by pyramid diffeomorphic deformation from CBCT images
Zechu ZHANG,Weilong PENG,Keke TANG,Zhaoyang YU,Asad Khan,Meie FANG
Journal of Zhejiang University (Science Edition)    2023, 50 (6): 701-710.   DOI: 10.3785/j.issn.1008-9497.2023.06.005
Abstract   HTML PDF (3611KB) ( 198 )  

Accurate and high-quality shape generation of individual teeth from cone-beam computerized tomography (CBCT) is essential for computer-aided dentistry. Existing methods need post-process to extract isosurfaces and the output meshes cannot be directly used as the input for most subsequent applications (such as finite element analysis (FEA). In this paper, we propose the network that directly learns the multi-resolution mesh guided by diffeomorphic deformation. Overall, our solution is a classic two-stage schema widely used in tooth reconstruction. Firstly, we adopt a revised anchor-free detector to locate each individual tooth with high precision. Then, we design the top-to-bottom flows from the multi-level features of each individual, referred to as pyramid flows, to predict diffeomorphic deformation from a sphere to a detailed tooth. Finally, we validate the effectiveness and efficiency of the proposed approach by comparing with the previous segmentation methods and other explicit surface learning-based methods in the experiment.

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The uniqueness and convergence of k-admissible solutions for a class of k-Hessian equations
Xingyue HE, Huanhuan DING
Journal of Zhejiang University (Science Edition)    2023, 50 (4): 424-428.   DOI: 10.3785/j.issn.1008-9497.2023.04.005
Abstract   HTML PDF (393KB) ( 196 )  

A class of coupled k-Hessian equations is considered. Firstly, by using the u0-sublinear theorem, it is proved that the equation has at most one radial k-admissible solution under the super-linear and sub-linear conditions. The uniqueness of radial k-admissible solution is verified by a numerical example. Finally, by incorporate with the monotone iterative technique, the uniform convergence of the solution is also discussed.

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Several identities and combinatorial proofs for compositions related to the part of size 1
Yuhong GUO
Journal of Zhejiang University (Science Edition)    2023, 50 (3): 261-265.   DOI: 10.3785/j.issn.1008-9497.2023.03.001
Abstract   HTML PDF (920KB) ( 189 )  

The compositions with part of size 1 at the left or the right of positive integers are studied, and the relation between these compositions and the Fibonacci numbers is obtained. And then using the well-known composition identities related to Fibonacci numbers, several new identities are obtained, The combinational bijective proofs are provided.

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Topological uniform descent and property (WE) for bounded linear operators
Nan LI,Xiaohong CAO
Journal of Zhejiang University (Science Edition)    2023, 50 (5): 551-557.   DOI: 10.3785/j.issn.1008-9497.2023.05.005
Abstract   HTML PDF (503KB) ( 177 )  

Let H be an infinite dimensional complex separable Hilbert space and B(H) be the algebra of all bounded linear operators on H. We call property (WE) holds for TB(H) if σ(T)\σw(T)=E(T), where σ(T) and σw(T) denote the spectrum and Weyl spectrum of T respectively, and E(T)={λiso?σ(T):?dimN(T-λI)>0}. By using the property of topological uniform descent of operators in this paper, the necessary and sufficient conditions for which the property (WE) holds for bounded linear operators and its functions are given. Furthermore, we show the applications of the main results, and explore the relationship of property (WE) between the Drazin invertible operator and its Drazin inverse.

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Reliability of Yule-Furry classic δ shock model
Ming MA, Lamaocuo, Bo PENG
Journal of Zhejiang University (Science Edition)    2023, 50 (5): 558-563.   DOI: 10.3785/j.issn.1008-9497.2023.05.006
Abstract   HTML PDF (570KB) ( 173 )  

Reliability is the primary topic in the theoretical research of reliability models, especially the premise for discussing other indicators in the δ shock model. In this paper, three methods including multiple integration method, independent convolution method and memoryless method are used to prove the system reliability of Yule-Furry classical δ shock model, and the similarities and differences between the three methods are analyzed. Based on the proof process of the memoryless method, the distribution function of the lifetime T is obtained, and a simple proof of reliability is derived.

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Robust multi-view clustering algorithm based on sparse consensus graph decomposition
Li GENG,Changpeng WANG
Journal of Zhejiang University (Science Edition)    2023, 50 (5): 569-579.   DOI: 10.3785/j.issn.1008-9497.2023.05.008
Abstract   HTML PDF (1924KB) ( 171 )  

Due to the increasing complexity of data form, multi-view clustering algorithms emerge one after another. The main disadvantages of existing methods include: the computational complexity of these methods is high; the final clustering involves additional processing steps; the similarity graph constructed may not be the optimal graph. In order to solve the above problems, a clustering algorithm based on sparse consensus graph decomposition is proposed. The algorithm is first tested on single-view data, and then extends from single-view data to multi-view data. The algorithm takes into account different contributions of different views to the final result by giving each view appropriate weight, at the same time, makes use of the L2,1 norm to obtain the consensus graph with better performance, learns the non-negative representation matrix on the basis of the consensus graph, and reveals the cluster result directly after alternation iteration. Finally, an update iterative algorithm is proposed and tested on a large number of data sets to verify the effectiveness of the algorithm.

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Purification effect of ex-situ ecological combined remediation system on different forms of phosphorus in tributaries of Jiulong River
Xiaoyu HAN, Hongda FANG, Jianjie LI, Binger LUO, Jiahui LIN, Xin WANG, Wanxin LIU, Junming HE, Jiayu ZHAI, Weibin LAN, Peiyong GUO
Journal of Zhejiang University (Science Edition)    2023, 50 (5): 588-596.   DOI: 10.3785/j.issn.1008-9497.2023.05.010
Abstract   HTML PDF (2080KB) ( 168 )  

This paper discusses the effect of ex-situ ecological combined remediation (ESECR) system on the purification of phosphorus of different forms in the polluted water of Pulin Creek, a tributary of Jiulong River, and each unit of ESECR treatment system is analyzed on the correlation between different phosphorus forms and environmental factors. Results showed that the average total removal rate of TP, DTP, DP and PP of ESECR treatment system were 84.3%, 84.4%, 90.8% and 78.9% respectively, among them the DP purification effect was the best. In each unit of ESECR treatment system, when the phosphorus content in the raw water was low, the sludge-membrane symbiotic (SSM) high efficiency coagulation water purification system had good TP, DTP and DP purification effect, the average removal rate were 81.4%, 76.0% and 84.8% respectively, the average removal rate of PP was 66.7%; when the content of phosphorus in the raw water was high, the average removal rate of TP, DTP and DP of the SSM high efficiency coagulation water purification system were 37.8%, 44.6% and 45.8%, nevertheless, the purification effect of PP was significant, and the average removal rate was 93.2%. When the processed water of the SSM high efficiency coagulation water purification system with low phosphorus content, the purification effect of ecological pond Ⅱ on TP and DTP was better than that of ecological pond Ⅰ, but the results on DP was opposite. For PP, the purification effect in ecological pond Ⅱ was better than that in ecological pond Ⅰ regardless of the impact of phosphorus content. The purification effect of ecological pond Ⅲ fluctuated, the purification effect on DP is relatively significant, and the average removal rate was 94.1%. In addition to the SSM high efficiency coagulation water purification system, the form of phosphorus in the polluted water of Pulin Creek and purified water by ESECR technology was mainly PP, and the percentage of each form in total phosphorus appeared as PP>DTP>DP. Pearson correlation analysis showed that different phosphorus forms were correlated with pH, water temperature and dissolved oxygen (DO) in ESECR treatment system.

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Efficient GPU parallel strategy for multi-scale topology optimization via asymptotic homogenization
Zhaohui XIA,Jianli LIU,Baichuan GAO,Tao NIE,Chen YU,Long CHEN,Jingui YU
Journal of Zhejiang University (Science Edition)    2023, 50 (6): 722-735.   DOI: 10.3785/j.issn.1008-9497.2023.06.007
Abstract   HTML PDF (4553KB) ( 162 )  

In response to the low computational efficiency in the context of multi-scale structural topology design, an efficient asymptotic homogenization GPU parallel strategy is presented. The strategy leverages the graphics processing unit (GPU) and investigates parallel strategies for level set initialization, large sparse stiffness matrix equations solving and constitutive properties computing. Experimental results demonstrate that the computing efficiency of the asymptotic homogenization can be greatly improved by adopting the parallel strategies, in particular, when refining a three-dimensional unit cell grid to a resolution of 100 000, the GPU parallel strategy achieves a speedup of two orders of magnitude compared to the CPU serial.

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Stability of monostable traveling waves for a class of SVIR models with nonlocal diffusion and delay
Xiaowu LI,Yunrui YANG,Kaikai LIU
Journal of Zhejiang University (Science Edition)    2023, 50 (3): 273-286.   DOI: 10.3785/j.issn.1008-9497.2023.03.003
Abstract   HTML PDF (670KB) ( 156 )  

The exponential stability of monostable traveling wave solutions of a class of SVIR model is established by using the weighted energy method and continuity method. In particular, the requirement for the initial perturbation need only be uniformly bounded at x=+ but not vanishing.

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Two-dimensional shape intrinsic symmetry detection algorithm based on functional map
Shengjun LIU,Zi TENG,Haibo WANG,Xinru LIU
Journal of Zhejiang University (Science Edition)    2023, 50 (6): 668-680.   DOI: 10.3785/j.issn.1008-9497.2023.06.002
Abstract   HTML PDF (4078KB) ( 154 )  

To address the problem that the performance of existing methods is unsatisfactory for detecting intrinsic symmetry in two-dimensional shapes, based on the flexible function mapping framework, we propose a spectral optimization method, named FM-2DSISD, to compute dense point maps for two-dimensional intrinsic symmetric shapes. Firstly, we design an algorithm robust to noise to extract sparse feature symmetry point maps. Secondly, using the feature symmetric point maps and the functional map framework, a mathematical model is developed whose optimization objective is to maintain the diagonality and orthogonality of each principal submatrix of the functional map matrix. We prove that the defined optimization objective can preserve the isometry of intrinsic symmetry maps. To solve the formula, we give an alternating iterative algorithm between the spatial and spectral domains via the spectral up-sampling technique. Numerical experiments show that the proposed algorithm performs better than the state-of-the-art methods on two-dimensional smooth shapes and noisy shapes.

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Focus+Context visualization based on optimal mass transportation
Kehua SU,Bailüe LIU,Na LEI,Kehan LI,Xianfeng GU
Journal of Zhejiang University (Science Edition)    2023, 50 (6): 681-691.   DOI: 10.3785/j.issn.1008-9497.2023.06.003
Abstract   HTML PDF (3910KB) ( 150 )  

In visualization field, Focus+Context techniques have been developed to visualize large, complex models on the display device with limited resolution. In this work, we propose a novel method for Focus+Context visualization based on optimal mass transportation. An optimal mass transportation map deforms a volume to itself, transforms the source measure (volumetric element) to the target measure with the minimal transportation cost. Solving the optimal mass transportation problem is equivalent to a convex optimization, and can be converted to computing power Voronoi diagrams in classical computational geometry. Comparing to existing approaches, the proposed method has solid theoretic foundation, which guarantees the existence, uniqueness and the smoothness of the solution. It allows the user to accurately control the target measure, and select multiple focus regions with irregular shapes. The resulting deformation is globally smooth and flipping free. Experiments with several volume data sets from medical applications and scientific simulations demonstrate the effectiveness and efficiency of our method.

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Genome-wide identification and expression analysis of Dimocarpus longanUBP family and its expression analysis under drought stress
Ning TONG, Chunyu ZHANG, Xiaoqiong XU, Xiaohui CHEN, Xu SHEN, Zhongxiong LAI
Journal of Zhejiang University (Science Edition)    2023, 50 (3): 367-377.   DOI: 10.3785/j.issn.1008-9497.2023.03.015
Abstract   HTML PDF (4667KB) ( 146 )  

Ubiquitin-specific protease (UBP) is the largest among the six families of deubiquitinating enzymes. It is widely found in eukaryotes and is highly conserved. They regulate the growth and development of various organisms through deubiquitination. In order to understand the biological function of DlUBP gene family and its role during somatic embryogenesis of Dimocarpus longan Lour. In this study, we performed genome-wide identification of DlUBP gene family members; analysed their genes structure, protein structure, promoter cis-acting elements and constructed phylogenetic tree based on the third-generation longan genome database and transcriptome database; then analyzed the expression of DlUBP under ABA treatment and drought stress. The results showed that the DlUBP gene family contains 18 members, which are divided into 10 subfamilies, the largest subfamily has four members; the number of amino acids are between 369-1 117, and the number of introns are between 2-31; There are a large number of light response elements, anaerobic induction response elements, and hormone response elements in the DlUBP promoter sequence with a prolonged procecsing time, the expression level of many DlUBP members showed a decreasing trend under abscisic acid treatment, and the expression level of many DlUBP genes increased under drought stress. It is speculated that the DlUBP gene family participates in the regulation of abscisic acid during somatic embryogenesis of longan and responses to drought stress.

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Multi-morphological design of TPMS-based microchannels with freeform boundary constraints
Guanhua YANG,Lei WU,Qinghui WANG,Zipeng CHI
Journal of Zhejiang University (Science Edition)    2023, 50 (6): 795-802.   DOI: 10.3785/j.issn.1008-9497.2023.06.014
Abstract   HTML PDF (5587KB) ( 143 )  

A multi-morphology design method based on conformal mapping is proposed to design triply periodic minimal surface (TPMS) microchannels with freeform boundary constraints. This method first maps the boundary of a freeform surface to a plane, allowing for channel topology design in the 2D parametric domain; Then, a Beta growth function algorithm based on loop is proposed to achieve smooth transitions of various TPMS morphological features; Finally, by mapping the designed microchannels to the 3D space constrained by the free surface, the microchannels meet the design requirements. Our results show that the microchannels constructed by this method have good adaptability to complex surface boundaries and can achieve the design goals of internal morphological features.

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MFDC-Net: A breast cancer pathological image classification algorithm incorporating multi-scale feature fusion and attention mechanism
Yuhua FANG,Feng YE
Journal of Zhejiang University (Science Edition)    2023, 50 (4): 455-464.   DOI: 10.3785/j.issn.1008-9497.2023.04.009
Abstract   HTML PDF (3135KB) ( 140 )  

Breast cancer is one of the most common malignant tumors in the world. Traditional methods take pathologists a lot of time and effort to diagnose, and the results are greatly affected by individual abilities. Using computer-aided diagnosis methods can improve the accuracy and efficiency of pathological image classification, meet the demands of clinical applications. To this end, a multi-scale feature fusion based on DenseNet and coordinate attention network (MFDC-Net) is proposed. The introduction of coordinate attention mechanism into the dense blocks can locate important feature spatial information precisely. The improved transition layers use average pooling and normal convolutions with different convolution kernels to reduce dimension and expand receptive fields. Finally the improved network employs a multi-scale feature fusion model using dilated convolution, average pooling and normal convolutions to fuse deep image features to improve classification performance. The experimental results show that MFDC-Net model has better classification performance, the accuracy rate of four classifications reaches 97.12%, the easily confused rate decreases to 3.34%. The method can better classify the histopathological images of breast cancer, and can provide an important basis for the diagnosis and treatment of doctors.

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The configurational transition of polyelectrolyte chain confined in a cylinder
Juxian GAO,Binyuan DING,Linli HE
Journal of Zhejiang University (Science Edition)    2023, 50 (5): 580-587.   DOI: 10.3785/j.issn.1008-9497.2023.05.009
Abstract   HTML PDF (1811KB) ( 140 )  

The configurational transition of polyelectrolyte chain confined in a cylinder was studied by means of coarse-grained molecular dynamics simulation. Specifically, the effects on the size and configuration transition of polyelectrolyte chain under the parameters of counterion valence, chain stiffness and confinement radius were studied by calculating the average radius of gyration, average persistence length, and average shape factor. It has been found that there are stable rod-like, globular, folded-chain and ring structures in confined space. In the case of trivalent counterions, the polyelectrolyte chain with moderate stiffness forms a stable ring structure, which can be well characterized by a tangent correlation function. The mechanism of condensation of polyelectrolyte chain and counterion is further explored by statistical analysis of polyelectrolyte chain and counterions distribution. Finally, the kinetic characteristics of the nucleation and growth of the ring structure are discussed, and the results agree with the experimental results. The results can provide a deep insight about the configurational behaviors of biological macromolecules in confined spaces.

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