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First-order primal-dual algorithm for sparse-view neutron computed tomography-based three-dimensional image reconstruction

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Nuclear Science and Techniques 2023年第8期34卷 35-53页

作者： Yang Liu Teng-fei zhu Zhi Luo xiao-ping Ouyang School of Nuclear Science and Engineering North China Electric Power UniversityBeijing 102206China State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi’an 710024China

Neutron computed tomography(NCT)is widely used as a noninvasive measurement technique in nuclear engineering,thermal hydraulics,and cultural *** neutron source intensity of NCT is usually low and the scan time is long,resulting in a projection image containing severe *** reduce the scanning time and increase the image reconstruction quality,an effective reconstruction algorithm must be *** CT image reconstruction,the reconstruction algorithms can be divided into three categories:analytical algorithms,iterative algorithms,and deep *** the analytical algorithm requires complete projection data,it is not suitable for reconstruction in harsh environments,such as strong radia-tion,high temperature,and high *** learning requires large amounts of data and complex models,which cannot be easily deployed,as well as has a high computational complexity and poor ***,this paper proposes the OS-SART-PDTV iterative algorithm,which uses the ordered subset simultaneous algebraic reconstruction technique(OS-SART)algorithm to reconstruct the image and the first-order primal–dual algorithm to solve the total variation(PDTV),for sparse-view NCT three-dimensional *** novel algorithm was compared with other algorithms(FBP,OS-SART-TV,OS-SART-AwTV,and OS-SART-FGPTV)by simulating the experimental data and actual neutron projection *** reconstruction results demonstrate that the proposed algorithm outperforms the FBP,OS-SART-TV,OS-SART-AwTV,and OS-SART-FGPTV algorithms in terms of preserving edge structure,denoising,and suppressing artifacts.

关键词： NCT First-order primal-dual algorithm OS-SART Total variation Sparse-view

3D robust anisotropic diffusion filtering algorithm for sparse view neutron computed tomography 3D image reconstruction

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Nuclear Science and Techniques 2024年第3期35卷 13-29页

The most critical part of a neutron computed tomography(NCT) system is the image processing algorithm,which directly affects the quality and speed of the reconstructed *** types of noise in the system can degrade the quality of the reconstructed ***,to improve the quality of the reconstructed images of NCT systems,efficient image processing algorithms must be *** anisotropic diffusion filtering(ADF) algorithm can not only effectively suppress the noise in the projection data,but also preserve the image edge structure information by reducing the diffusion at the image ***,we propose the application of the ADF algorithm for NCT image *** compare the performance of different algorithms in NCT systems,we reconstructed images using the ordered subset simultaneous algebraic reconstruction technique(OS-SART) algorithm with different regular terms as image processing *** the iterative reconstruction,we selected two image processing algorithms,the Total Variation and split Bregman solved total variation algorithms,for comparison with the performance of the ADF ***,the filtered back-projection algorithm was used for comparison with an iterative *** reconstructing the projection data of the numerical and clock models,we compared and analyzed the effects of each algorithm applied in the NCT *** on the reconstruction results,OS-SART-ADF outperformed the other algorithms in terms of denoising,preserving the edge structure,and suppressing *** example,when the 3D Shepp–Logan was reconstructed at 25 views,the root mean square error of OS-SART-ADF was the smallest among the four iterative algorithms,at only *** universal quality index,mean structural similarity,and correlation coefficient of the reconstructed image were the largest among all algorithms,with values of 0.9877,0.9878,and 0.9887,respectively.

关键词： NCT OS-SART Sparse-view Anisotropic diffusion filtering

Sparse-view neutron CT 3D image reconstruction algorithm based on split Bregman method

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Nuclear Science and Techniques 2024年第9期35卷 41-55页

作者： Teng-fei zhu Yang Liu Zhi Luo xiao-ping Ouyang School of Nuclear Science and Engineering North China Electric Power UniversityBeijing 102206China State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi’an 710024China

As a complement to X-ray computed tomography(CT),neutron tomography has been extensively used in nuclear engineer-ing,materials science,cultural heritage,and industrial *** of the attenuation matrix for neutron tomography with a traditional analytical algorithm requires hundreds of projection views in the range of 0°to 180°and typically takes several hours to *** a low time-resolved resolution degrades the quality of neutron *** the number of projection acquisitions is an important approach to improve the time resolution of images;however,this requires efficient reconstruction ***,sparse-view reconstruction algorithms in neutron tomography need to be *** this study,we investigated the three-dimensional reconstruction algorithm for sparse-view neu-tron CT *** enhance the reconstructed image quality of neutron CT,we propose an algorithm that uses OS-SART to reconstruct images and a split Bregman to solve for the total variation(SBTV).A comparative analysis of the performances of each reconstruction algorithm was performed using simulated and actual experimental *** to the analyzed results,OS-SART-SBTV is superior to the other algorithms in terms of denoising,suppressing artifacts,and preserving detailed structural information of images.

关键词： Neutron CT OS-SART Sparse-view 3D reconstruction Split Bregman Total variation

Laparoscopic distal pancreatectomy is as safe and feasible as open procedure:A meta-analysis

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World Journal of Gastroenterology 2012年第16期18卷 1959-1967页

作者： Kun Xie Yi-ping zhu xiao-Wu xu Ke Chen Jia-fei Yan Yi-ping Mou Department of General Surgery Sir Run Run Shaw HospitalSchool of MedicineZhejiang UniversityHangzhou 310016Zhejiang ProvinceChina

AIM:To evaluate the feasibility and safety of laparoscopic distal pancreatectomy(LDP) compared with open distal pancreatectomy(ODP).METHODS:Meta-analysis was performed using the databases,including PubMed,the Cochrane Central Register of Controlled Trials,Web of Science and BIOSIS *** should contain quantitative data of the comparison of LDP and *** article was reviewed by two *** of operative time,spleen-preserving rate,time to fluid intake,ratio of malignant tumors,postoperative hospital stay,incidence rate of pancreatic fistula and overall morbidity rate were ***:Nine articles with 1341 patients who underwent pancreatectomy met the inclusion *** was performed in 501(37.4%) patients,while ODP was performed in 840(62.6%) *** were significant differences in the operative time,time to fluid intake,postoperative hospital stay and spleen-preserving rate between LDP and *** was no difference between the two groups in pancreatic fistula rate [random effects model,risk ratio(RR) 0.996(0.663,1.494),P = 0.983,I2 = 28.4%] and overall morbidity rate [random effects model,RR 0.81(0.596,1.101),P = 0.178,I2 = 55.6%].CONCLUSION:LDP has the advantages of shorter hospital stay and operative time,more rapid recovery and higher spleen-preserving rate as compared with ODP.

关键词： Laparoscopy Distal pancreatectomy Pancreatic fistula Spleen-preserving Morbidity

Dynamics and Thermodynamics of Porous HMX-like Material Under Shock

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Communications in Theoretical Physics 2009年第11期52卷 901-908页

作者： xu Ai-Guo ZHANG Guang-Cai ZHANG ping PAN xiao-fei zhu Jian-Shi National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P.O.Box 8009-26 Beijing 100088 China

Strong shock may induce complex processes in porous materials. We use the newly developed materialpoint-method to simulate such processes in an HMX-like material. To pick out relevant information, morphological characterization is used to treat with the temperature map. Via the Minkowski funetional analysis the dynamics and thermodynamics of the shock wave reaction on porous HMX-like material are studied. The geometrical and topological properties of the ＂hot-spots＂ are revealed. Numerical results indicate that, shocks in porous materials are not simple jump states as classically viewed, but rather are a complex sequence of compressions and rarefactions. They cover a broad spectrum of states. We can use coarse-grained description to the wave series. A threshold value of temperature presents a Turing pattern dynamical procedure. A higher porosity is generally preferred when the energetic material needs a higher temperature for initiation. The technique of data analysis can be used to other physical quantities, for example, density, particle velocity, some specific stress, etc. From a series of studies along the line, one may get a large quantity of information for desiring the fabrication of material and choosing shock strength according to what needed is scattered or connected ＂hot-spots＂. PACS numbers： ***, 05 Key words： porous material 70.-a, 05.40.-a, *** shock wave, Minkowski functionals

关键词： porous material shock wave Minkowski functionals

Pt-Ni nanourchins as electrocatalysts for oxygen reduction reaction

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Frontiers in Energy 2017年第3期11卷 254-259页

作者： Qiaowan CHANG Yuan xu Shangqian zhu fei xiao Minhua SHAO Department of Chemical and Biomolecular Engineering Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong China Department of Chemical and Biomolecular Engineering Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong China Energy Institute Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong China

Pt-Ni bimetallic alloys with various nanos-tructures have shown excellent activity toward oxygen reduction reaction （ORR）. The ORR activity is highly dependent on the structure of the catalyst. In this paper, Pt-Ni nanourchins were synthesized with an average size of 50 nm consisting of 10-20 nanorods and nanooctahedra by adjusting the synthesis condition. The formation of Pt-Ni nanourchins is mainly dependent on the adding order of solvents （benzyl ether, oleylamine and oleic acid）. Pt-Ni nanourchins present a reasonable high ORR activity （0.81 A/mg at 0.9 V）.

关键词： Pt-Ni alloys nanourchins oxygen reduction reaction shape control fuel cells

Cooperative effect between copper species and oxygen vacancy in Ce_(0.7−x)Zr_(x)Cu_(0.3)O_(2) catalysts for carbon monoxide oxidation

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Frontiers of Chemical Science and Engineering 2021年第6期15卷 1524-1536页

作者： Shan Wang xuelian xu ping xiao Junjiang zhu Xinying Liu Institute for the Development of Energy for African Sustainability College of ScienceEngineering and TechnologyUniversity of South AfricaJohannesburg1710South Africa Hubei Key Laboratory of Biomass Fibers and Eco-dyeing&Finishing College of Chemistry and Chemical EngineeringWuhan Textile UniversityWuhan430200China

The effects of Zr doping on the existence of Cu and the catalytic performance of Ce_(0.7−x)Zr_(x)Cu_(0.3)O_(2)for CO oxidation were *** characterization results showed that all samples have a cubic structure,and a small amount of Zr doping facilitates Cu^(2+) ions entering the CeO2 lattice,but excessive Zr doping leads to the formation of surface CuO crystals ***,the number of oxygen vacancies caused by the Cu^(2+) entering the lattice(e.g.,Cu^(2+)-□-Ce^(4+);□:oxygen vacancy),and the amount of reducible copper species caused by CuO crystals,varies with the Zr *** CO oxidation tests indicated that the oxygen vacancy and the reducible copper species were the adsorption and activation sites of O_(2)and CO,respectively,and the cooperative effects between them accounted for the high CO oxidation ***,the samples x=0.1 and 0.3,which possessed the most oxygen vacancy or reducible copper species,showed the best activity for CO oxidation,with full CO conversion obtained at 110℃.The catalyst is also stable and has good resistance to water during the reaction.

关键词： Ce-Zr-Cu-O CO oxidation reducible copper species oxygen vacancy cooperative effect

Properties of High Basicity Mold Fluxes for Peritectic Steel Slab Casting

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Journal of Iron and Steel Research International 2012年第7期19卷 39-45页

作者： LONG xiao HE Sheng-ping xu Jian-fei HUO xu-ling WANG Qian Chongqing Key Laboratory of Metallurgical Engineering College of Materials Science and EngineeringChongqing UniversityChongqing 400044China

In high speed continuous casting of peritectic steel slabs, mold fluxes with high basicity are required for less surface defect product. However, the basicity of remaining liquid slag film tends to decrease in casting process because of the crystallization of 3CaO ·2SiO2 · CaF2. Thus, a way is put forward to improve mold fluxesr properties by raising the original basicity. In order to confirm the possibility of this method, the effect of rising original basicity on the properties of mold fluxes is discussed. Properties of high fluorine based mold fluxes with different basicities and contents of CaF2 , Na2 O, and MgO were measured, respectively. Then, properties of higher basicity mold fluxes were discussed and compared with traditional ones. The results show that increasing the basicity index can improve the melting and flow property of mold fluxes. With the increasing basicity, crystallization rate of mold fluxes increases obviously and crystallization temperature tends to decrease when the basicity exceeds 1.35. The method presen- ted before is proved as a potential way to resolve the contradiction between horizontal heat transfer controlling and solidified shell lubricating for peritectic steel slab casting. But further study on improving the flow property of liquid slag is needed. This work can be used to guide mold fluxes design for high speed continuous casting of peritectic steel slabs.

关键词： mold flux high basicity crystallization property peritectic steel

Three-Dimensional Multi-mesh Material Point Method for Solving Collision Problems

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Communications in Theoretical Physics 2008年第5期49卷 1129-1138页

作者： PAN xiao-fei xu Ai-Guo ZHANG Guang-Cai ZHANG ping zhu Jian-Shi MA Shang ZHANG Xiong Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P.O. Box 8009-26 Beijing 100088 China School of Aerospace Tsinghua University Beijing 100084 China

A new multi-mesh contact algorithm for three-dimensional material point method is presented. The contact algorithm faithfully recovers the opposite acting forces between colliding bodies. Collision procedures between regular bodies and/or rigid bodies are treated within the same framework. Multi-value of momentum and mass are defined on every node to describe the contact/sliding/separation procedure. Both normal and tangential velocities of each particle at the contact surface are calculated in respective individual mesh. A Coulomb friction is applied to describe the sliding or slipping between the contacting bodies. The efficiency of the contact algorithm is linearly related to the number of the contacting bodies because the overlapped nodes are labeled by sweeping the material particles of all bodies when the nodal momentum and mass are formed at every time step. Numerical simulation shows that our contact algorithm possesses high accuracy and low numerical energy dissipation, which is very important for solving collision problems.

关键词： material-point method (MPM) energy conservation contact algorithm multi-mesh