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SDCC: software-defined collective communication for distributed training

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Science China(Information Sciences) 2024年第9期67卷 105-125页

作者： Xin JIN Zhen ZHANG yunshan JIA yun MA Xuanzhe liu School of Computer Science Peking University Department of Computer Science and Technology Johns Hopkins University

Communication is crucial to the performance of distributed training. Today's solutions tightly couple the control and data planes and lack flexibility, generality, and performance. In this study, we present SDCC, a software-defined collective communication framework for distributed training. SDCC is based on the principle of modern systems design to effectively decouple the control plane from the data *** abstracts the operations for collective communication in distributed training with dataflow operations and unifies computing and communication with a single dataflow graph. The abstraction, together with the unification, is powerful: it enables users to easily express new and existing collective communication algorithms and optimizations, simplifies the integration with different computing engines(e.g., Py Torch and Tensor Flow) and network transports(e.g., Linux TCP and kernel bypass), and allows the system to improve performance by exploiting parallelism exposed by the dataflow graph. We further demonstrate the benefits of SDCC in four use cases.

关键词： machine learning systems distributed training deep learning collective communication software-defined networking

Inverse Eigenvalue Problems and Their Associated Approximation Problems for Matrices with J-（Skew） Centrosymmetry

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Inverse Eigenvalue Problems and Their Associated Approximati...

Novel subtype of obesity influencing the outcomes of sleeve gastrectomy:Familial aggregation of obesity

第三届最优化与系统生物学国际研讨会

作者： zhong-yun liu You-Cai Duan yun-Feng Lai Yu-Lin Zhang School of Math. Changsha University of Science & Technology Dept.of Math. University of MinhoCampus de Gualtar4710-057 BragaPortugal

＜正＞The inverse problems play an important role in MEG reconstructions[3,4,5,6,7].In this paper,a partially described inverse eigenvalue problem and an associated optimal approximation problem for J-centrosymmetric matrices are considered *** is shown under which conditions the inverse eigenproblem has a *** expression of its general solution is given. In case a solution of the inverse eigenproblem exists,the optimal approximation problem can be *** formula of its unique solution is ***,the case for /-skew centrosymmetric matrices is considered.

关键词： J-centrosymmetric matrices J-skew centrosymmetric Inverse eigenvalue problem optimal approximation

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World Journal of Gastroenterology 2024年第13期30卷 1887-1898页

作者： Ze-Yu Wang yun-Fei Qu Tian-Ming Yu Zeng-Lin liu Yu-Gang Cheng Ming-Wei zhong San-Yuan Hu Department of General Surgery The First Affiliated Hospital of Shandong First Medical University and Shandong Provincial Qianfoshan HospitalJinan 250000Shandong ProvinceChina Department of Postgraduate Shandong First Medical University and Shandong Academy of Medical SciencesJinan 250000Shandong ProvinceChina Department of General Surgery Shandong Provincial Qianfoshan HospitalCheeloo College of Medicine Shandong UniversityJinan 250000Shandong ProvinceChina State Key Laboratory of Integration and Innovation of Classic Formula and Modern Chinese Medicine Lunan Pharmaceutical Group Co.Ltd.Linyi 276005Shandong ProvinceChina

BACKGROUND Differences in the preoperative characteristics and weight loss outcomes after sleeve gastrectomy(SG)between patients with familial aggregation of obesity(FAO)and patients with sporadic obesity(SO)have not been *** To explore the impact of SG on weight loss and the alleviation of obesity-related comorbidities in individuals with *** A total of 193 patients with obesity who underwent SG were *** with FAO/SO were matched 1:1 by propensity score matching and were categorized into 4 groups based on the number of first-degree relatives with obesity(1 SO vs 1FAO,2SO vs 2FAO).The baseline characteristics,weight loss outcomes,prevalence of obesity-related comorbidities and incidence of major surgeryrelated complications were compared between *** We defined FAO as the presence of two or more first-degree relatives with *** with FAO did not initially show significant differences in baseline data,short-term postoperative weight loss,or obesity-related comorbidities when compared to patients with SO ***,distinctions between the two groups became evident at the two-year mark,with statistically significant differences in both percentage of total weight loss(P=0.006)and percentage of excess weight loss(P<0.001).The FAO group exhibited weaker remission of type 2 diabetes mellitus(T2DM)(P=0.031),hyperlipidemia(P=0.012),and non-alcoholic fatty liver disease(NAFLD)(P=0.003)as well as a lower incidence of acid reflux(P=0.038).CONCLUSION FAO patients is associated with decreased mid-to-long-term weight loss outcomes;the alleviation of T2DM,hyperlipidemia and NAFLD;and decreased incidence of acid reflux postoperatively.

关键词： Obesity Bariatric surgery Sleeve gastrectomy Family history Weight loss

Flexo-photocatalysis in centrosymmetric semiconductors

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Nano Research 2024年第3期17卷 1173-1181页

作者： Kang liu Tong Wu Luying Xu Zhuangzhuang Zhang Zhiyu liu Longfei Wang zhong Lin Wang Center on Nanoenergy Research School of Physical Science&TechnologyGuangxi UniversityNanning 530004China Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of SciencesBeijing 101400China College of Nanoscience and Technology University of Chinese Academy of SciencesBeijing 100049China Georgia Institute of Technology AtlantaGA 30332-0245USA Yonsei Frontier Lab Yonsei UniversitySeoul 03722Republic of Korea

The separation of photogenerated electron–hole pairs is vitally important for photocatalysis,which can be effectively promoted by polarization ***,it only manifests in piezoelectric/pyroelectric/ferroelectric materials that have a non-centrosymmetric ***,we demonstrate that the polarization enhanced photocatalysis(with wide spectra from ultraviolet(UV)light to visible light)can be achieved in centrosymmetric semiconductors,such asδ-MnO_(2) and TiO_(2) nanosheets integrated nanoflowers,by using the strain-gradient-induced flexoelectric polarization that is always overlooked in polarization-enhanced *** ultrasonic and illumination excitation,the organic pollutants(methylene blue(MB),etc.)can be effectively degraded within 30 min with excellent stability and *** with photocatalysis,the flexo-photocatalytic performance of above centrosymmetric semiconductors is substantially increased by 85%.Moreover,the factors related to flexo-photocatalysis such as material morphology,mechanical stimuli source,and adsorption are explored to deeply understand the mechanism of *** work opens up a way for high-performance photocatalysis in centrosymmetric semiconductors.

关键词： piezo-photocatalysis photocatalysis flexoelectricity polarization centrosymmetric semiconductor

A novel silver-doped nickel oxide hole-selective contact for crystalline silicon heterojunction solar cells

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Frontiers of Chemical Science and Engineering 2024年第2期18卷 93-101页

作者： Junfeng Zhao Xudong Yang zhongqing Zhang Shengpeng Xie Fangfang liu Anjun Han Zhengxin liu yun Sun Wei liu Key Laboratory of Photoelectronic Thin Film Devices and Technology of Tianjin Engineering Research Center of Thin Film Photoelectronic TechnologyInstitute of Photoelectronic Thin Film Devices and Technology of Nankai University(Ministry of Education)Tianjin 300350China Shanghai Institute of Microsystem and Information Technology Chinese Academy of SciencesShanghai 201800China

Based on its band alignment,p-type nickel oxide(NiO_(x))is an excellent candidate material for hole transport layers in crystalline silicon heterojunction solar cells,as it has a smallΔEV and largeΔEC with crystalline ***,to overcome the poor hole selectivity of stoichiometric NiO_(x) due to its low carrier concentration and conductivity,silver-doped nickel oxide(NiO_(x):Ag)hole transport layers with high carrier concentrations were prepared by co-sputtering high-purity silver sheets and pure NiO_(x) *** improved electrical conductivity of NiO_(x) was attributed to the holes generated by the Ag^(+)substituents for Ni^(2+),and moreover,the introduction of Ag^(+)also increased the amount of Ni^(3+)present,both of which increased the carrier concentration in NiO_(x).Ag^(+)doping also reduced the c-Si/NiO_(x) contact resistivity and improved the hole-selective contact with NiO_(x).Furthermore,the problems of particle clusters and interfacial defects on the surfaces of NiO_(x):Ag films were solved by UV-ozone oxidation and high-temperature annealing,which facilitated separation and transport of carriers at the c-Si/NiO_(x) *** constructed c-Si/NiO_(x):Ag solar cell exhibited an increase in open-circuit voltage from 490 to 596 mV and achieved a conversion efficiency of 14.4%.

关键词： band alignment nickel oxide hole transport layer silver-doped nickel oxide UV-ozone

Geobacter sulfurreducens promoted the biosynthesis of reduced graphene oxide and coupled it for nitrobenzene reduction

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Journal of Environmental Sciences 2024年第4期138卷 458-469页

作者： Shoujuan Zhang Qi liu Linrui zhong Jianhong Jiang Xiaozhe Luo Xingxin Hu Qian liu Yue Lu College of Environmental Science and Engineering Hunan UniversityChangsha 410082China Shenzhen Research Institute Hunan UniversityShenzhen 510082China Key Laboratory of Environment Biology and Pollution Control Hunan UniversityMinistry of EducationChangsha 410082China China Machinery International Engineering Design&Research Institute Co. LtdChangsha 410007China Hunan Engineering Research Center for Water Treatment Process&Equipment Changsha 410007China

In order to explore an efficient and green method to deal with nitrobenzene(NB)pollutant,reduced graphene oxide(r GO)as an electron shuttle was applied to enhance the extracellular electron transfer(EET)process of Geobacter sulfurreducens,which was a typical electrochemically active bacteria(EAB).In this study,r GO biosynthesis was achieved via the reduction of graphene oxide(GO)by *** PCA within 3 ***,the r GOPCA combining system completely reduced 50-200μmol/L of NB to aniline as end product within one *** characterization revealed that PCA cells were partly wrapped by rGO,and therefore the distance of electron transfer between strain PCA and r GO material was ***,the ID/IGof GO,r GO,and r GO-PCA combining system were 0.990,1.293 and 1.31,***,highest currents were observed in r GO-PCA-NB as 12.950μA/-12.560μA at -408 m V/156 m V,attributing to the faster electron transfer efficiency in EET ***,the NB reduction was mainly due to:(I)direct EET process from *** PCA to NB;(II)r GO served as electron shuttle and accelerated electron transfer to NB,which was the main degradation ***,the biosynthesis of r GO via GO reduction by Geobacter promoted the NB removal process,which provided a facile strategy to alleviate the problematic nitroaromatic pollution in the environment.

关键词： Reduced graphene oxide Geobacter Nitrobenzene Removal Extracellular electron transfer

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Superconvergence of Direct Discontinuous Galerkin Methods:Eigen-structure Analysis Based on Fourier Approach

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Communications on Applied Mathematics and Computation 2024年第1期6卷 257-278页

作者： Xuechun liu Haijin Wang Jue Yan Xinghui zhong School of Mathematical Sciences Zhejiang UniversityHangzhou310027ZhejiangChina School of Science Nanjing University of Posts and TelecommunicationsNanjing210023JiangsuChina Department of Mathematics Iowa State UniversityAmes50011IAUSA

This paper investigates superconvergence properties of the direct discontinuous Galerkin(DDG)method with interface corrections and the symmetric DDG method for diffusion *** apply the Fourier analysis technique to symbolically compute eigenvalues and eigenvectors of the amplification matrices for both DDG methods with different coefficient settings in the numerical *** on the eigen-structure analysis,we carry out error estimates of the DDG solutions,which can be decomposed into three parts:(i)dissipation errors of the physically relevant eigenvalue,which grow linearly with the time and are of order 2k for P^(k)(k=2,3)approximations;(ii)projection error from a special projection of the exact solution,which is decreasing over the time and is related to the eigenvector corresponding to the physically relevant eigenvalue;(iii)dissipative errors of non-physically relevant eigenvalues,which decay exponentially with respect to the spatial mesh sizeΔ*** observe that the errors are sensitive to the choice of the numerical flux coefficient for even degree P^(2)approximations,but are not for odd degree P^(3)*** experiments are provided to verify the theoretical results.

关键词： Direct discontinuous Galerkin(DDG)method with interface correction Symmetric DDG method Superconvergence Fourier analysis Eigen-structure

Viscoacoustic generalized screen propagator in constant-Q model

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Petroleum Science 2024年第4期21卷 2356-2369页

作者： zhong-Kui Dai Jia-Chun You Xing-Guo Huang Wei liu College of Geophysics Chengdu University of Technology College of Instrumentation and Electrical Engineering Jilin University

When seismic waves propagate through the geological formation, there is a significant loss of energy and a decrease in imaging resolution, because of the viscoacoustic properties of subsurface medium. This profoundly impacts seismic wavefield propagation, imaging and interpretation. To accurately image the true structure of subsurface medium, the consensus among geophysicists is to no longer treat subsurface medium as ideal homogeneous medium, but rather to incorporate the viscoacoustic properties of subsurface medium. Based on the generalized screen propagator using conventional acoustic wave equation(acoustic GSP), our developed method introduces viscoacoustic compensation strategy, and derives a one-way wave generalized screen propagator based on time-fractional viscoacoustic wave equation(viscoacoustic GSP). In numerical experiments, we conducted tests on two-dimensional multi-layer model and the Marmousi model. When comparing with the acoustic GSP using the acoustic data, we found that the imaging results of the viscoacoustic GSP using the viscoacoustic data showed a significant attenuation compensation effect, and achieved imaging results for both algorithms were essentially consistent. However, the imaging results of acoustic GSP using viscoacoustic data showed significant attenuation effects, especially for deep subsurface imaging. This indicates that we have proposed an effective method to compensate the attenuated seismic wavefield. Our application on a set of real seismic data demonstrated that the imaging performance of our proposed method in local areas surpassed that of the conventional acoustic GSP. This suggests that our proposed method holds practical value and can more accurately image real subsurface structures while enhancing imaging resolution compared with the conventional acoustic GSP. Finally, with respect to computational efficiency, we gathered statistics on running time to compare our proposed method with conventional Q-RTM, and it is evid

关键词： One-way wave equation Viscoacoustic wave equation Generalized screen propagator Attenuation and dispersion effects

Tracking Regulatory Mechanism of Trace Fe on Graphene Electromagnetic Wave Absorption

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Nano-Micro Letters 2024年第4期16卷 79-96页

作者： Kaili Zhang Yuhao liu Yanan liu Yuefeng Yan Guansheng Ma Bo zhong Renchao Che Xiaoxiao Huang School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001People’s Republic of China MIIT Key Laboratory of Advanced Structural‑Functional Integration Materials&Green Manufacturing Technology Harbin Institute of TechnologyHarbin 150001People’s Republic of China School of Materials Science and Engineering Harbin Institute of Technology at WeihaiWeihai 264209People’s Republic of China Laboratory of Advanced Materials Shanghai Key Lab of Molecular Catalysis and Innovative MaterialsFudan UniversityShanghai 200438People’s Republic of China

Polarization and conductance losses are the fundamental dielectric attenuation mechanisms for graphene-based absorbers, but it is not fully understood in revealing the loss mechanism of affect graphene itself. For the first time, the reduced graphene oxide(RGO) based absorbers are developed with regulatory absorption properties and the absorption mechanism of RGO is mainly originated from the carrier injection behavior of trace metal Fe nanosheets on graphene. Accordingly, the minimum reflection loss(RLmin) of Fe/RGO-2composite reaches-53.38 dB(2.45 mm), and the effective absorption bandwidth achieves 7.52 GHz(2.62 mm) with lower filling loading of 2 wt%. Using off-axis electron hologram testing combined with simulation calculation and carrier transport property experiments, we demonstrate here the carrier injection behavior from Fe to graphene at the interface and the induced charge accumulation and rearrangement, resulting in the increased interfacial and dipole polarization and the conductance loss. This work has confirmed that regulating the dielectric property of graphene itself by adding trace metals can not only ensure good impedance matching, but also fully exploit the dielectric loss ability of graphene at low filler content,which opens up an efficient way for designing lightweight absorbers and may be extended to other types materials.

关键词： Reduced graphene oxide Fe nanosheets Dielectric loss Electromagnetic wave absorption

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