检索结果-南通市图书馆

Kernel sparse representation for MRI image analysis in automatic brain tumor segmentation

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2018年第4期19卷 471-480页

作者： Ji-jun TONG Peng ZHANG yu-xiang weng Dan-hua ZHU School of lnformation Science and Technology Zhejiang Sci-Tech UniversityHangzhou 310018China Department of Neurosurgery The First Affiliated HospitalSchool of MedicineZhejiang UniversityHangzhou 310003China State Key Laboratory for Diagnosis and Treatment of lnfectious Diseases Collaborative Innovation Center for Diagnosis and Treatment of Infectious DiseasesThe First Affiliated HospitalSchool of MedicineZhejiang UniversityHangzhou 310003China

The segmentation of brain tumor plays an important role in diagnosis, treatment planning, and surgical simulation. The precise segmentation of brain tumor can help clinicians obtain its location, size, and shape information. We propose a fully automatic brain tumor segmentation method based on kernel sparse coding. It is validated with 3D multiple-modality magnetic resonance imaging(MRI). In this method, MRI images are pre-processed first to reduce the noise, and then kernel dictionary learning is used to extract the nonlinear features to construct five adaptive dictionaries for healthy tissues, necrosis, edema, non-enhancing tumor, and enhancing tumor tissues. Sparse coding is performed on the feature vectors extracted from the original MRI images, which are a patch of m×m×m around the voxel. A kernel-clustering algorithm based on dictionary learning is developed to code the voxels. In the end, morphological filtering is used to fill in the area among multiple connected components to improve the segmentation quality. To assess the segmentation performance, the segmentation results are uploaded to the online evaluation system where the evaluation metrics dice score, positive predictive value(PPV), sensitivity, and kappa are used. The results demonstrate that the proposed method has good performance on the complete tumor region(dice: 0.83; PPV: 0.84; sensitivity: 0.82), while slightly worse performance on the tumor core(dice: 0.69; PPV: 0.76; sensitivity: 0.80) and enhancing tumor(dice: 0.58; PPV: 0.60; sensitivity: 0.65). It is competitive to the other groups in the brain tumor segmentation challenge. Therefore, it is a potential method in differentiation of healthy and pathological tissues.

关键词： Brain tumor segmentation Kernel method Sparse coding Dictionary learning

Transitional Process of Ploy（N-isopropylacrylamide） in Deuterated Solution

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2009年第5期22卷 447-452,I0001页

作者： Shao-hua Zhang Yang Chen Heng Li yu-xiang weng Hefei National Laboratory for Physical Sciences at the Microscale Department of Chemical PhysicsUniversity of Science and Technology of China Hefei 230026 China Laboratory of Soft Matter Physics Institute of Physics Chinese Academy of Sciences Beijing National Laboratory of Condensed Matter Physics Beijing 100080 China

在 deuterated 答案的计策(N-isopropylacrylamide )(PNIPAM ) 的快阶段过渡的进程被激光学习导致的温度跳在毫微秒水平上与解决时间的中间红外线的吸收度差别光谱学相结合的技术。在 15651700 cm-1 的精力范围之中的 PNIPAM 的酰胺 I'... 详细信息

在 deuterated 答案的计策(N-isopropylacrylamide )(PNIPAM ) 的快阶段过渡的进程被激光学习导致的温度跳在毫微秒水平上与解决时间的中间红外线的吸收度差别光谱学相结合的技术。在 15651700 cm-1 的精力范围之中的 PNIPAM 的酰胺 I' 乐队的多山峰试验性地被解决到三个组(我， ii， iii ) 第一次，当时在阶段的不同三阶段的过程长链的 PNIPAM 的过渡过程也第一被观察。而且，合适的任务也被走向在酰胺 I' 乐队的三座组山峰和在动力学的三步长链的 PNIPAM 处理。

关键词：聚异丙基烯酰胺激光诱导温度跃变动力学相变过程

An integrative mathematical model of microwave ion thruster for mHz-frequency thrust noise analysis

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第4期37卷 121-136页

作者： xiang NIU Hui LIU Daren yu Plasma Propulsion Laboratory Harbin Institute of TechnologyHarbin 150001China

Many high-precision space missions need thrusters to produce thrust with low noise to compensate for disturbances and ensure satellite platform stability. Microwave ion thruster is characterized with a wide thrust range and potential for these missions. A cost-effective and accurate mathematical model is crucial for mHz-frequency thrust noise analysis and feedback controller design. The Particle-In-Cell(PIC) and global models are two common simulation tools. The PIC model is characterized with high accuracy but huge computation cost, which is difficult to analyze long-time performance characteristics. Now, the global model is only used for the discharge chamber with low accuracy and cannot reflect ion extraction properties. In this paper, an integrative mathematical model is built for a 1-cm microwave ion thruster and can reflect ion beamlet divergence and impingement on the Accelerator Grid(AG). Simulation results show good agreement with experiments at 0.06 sccm. However, the model demonstrates worse consistency with experiments when the flux increases to 0.1 sccm, which may be because the influence of neutral gas on the Electron Cyclotron Resonance(ECR) is not considered in the model. A long-time(1000 s) simulation is conducted with this model under 35 μN. It takes 3 hrs, and the thrust noise reaches 1 μN/Hz^(0.5) at 1 mHz.

关键词： Electric propulsion Microwave ion thruster Integrative model Sheath property Ion beamlet divergence Thrust noise Plasma

Construction of the Apparatus for Two Dimensional Electronic Spectroscopy and Characterization of the Instrument

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2015年第4期28卷 -页

作者： Shuai yue Zhuan Wang Xiao-chuan He Gang-bei Zhu yu-xiang weng Laboratory of Soft Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China

This work describes the construction of a phase-stable two dimensional electronic spectrometer operating in a photon echo mode with optical heterodyne detection, where the diffractive optics were used to realize the passive phase stabilization. In addition, a high speed and sensitive EMCCD was configured for shot-to-shot measurement which effectively improved signal-to-noise ratio. Consequently, the phase stability between a pulse pair split by the diffractive optics was determined in terms of standard deviation to be λ/200 during an observation period of 30 min, while the phase stability of the photon echo signal measured with IR140 is λ/90 in 19 min. In addition, a method of phase-shift in the pump pulse is also presented, which can effectively remove the interference from scattering light in collection of pump-probe transient absorption spectrum. The phase-shift method can improve the accuracy of phase adjustment in 2D electronic spectrum of scattering samples.

关键词： Two-dimensional electronic spectroscopy Phase stability Phase adjustment

Microstructure and mechanical properties of a cast TRIP-assisted multiphase stainless steel

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Foundry 2024年第3期21卷 221-228页

作者： Meng-xin Wang Zi-xiang Wu Jing-yu He xiang Chen School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing 100084China

Stainless steels are used in a wide range of complex environments due to their excellent corrosion *** stainless steels can offer an excellent combination of strength,toughness and corrosion resistance due to the coexistence of different *** microstructure and mechanical properties of a novel cast multiphase stainless steel,composed of martensite,ferrite,and austenite,were investigated following appropriate heat treatment processes:solution treatment at 1,050℃ for 0.5 h followed by water quenching to room temperature,and aging treatment at 500℃ for 4 h followed by water quenching to room *** show reversed austenite is formed by diffusion of Ni element during aging process,and the enrichment of Ni atoms directly determines the mechanical stability of *** austenite with a lower Ni content undergoes a martensitic transformation during plastic *** tensile strength of the specimen exceeds 1,100 MPa and the elongation exceeds 24%after solid solution,and further increases to 1,247 MPa and 25%after aging *** enhancement is due to the TRIP effect of austenite and the precipitation of the nanoscale G-phase pinning dislocations in ferrite and martensite.

关键词： multiphase stainless steel mechanical properties TRIP effect reversed austenite G-phase

103 GHz germanium-on-silicon photodiode enabled by an optimized U-shaped electrode

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2024年第1期12卷 1-6页

作者： Yang Shi xiang Li Mingjie Zou yu yu Xinliang Zhang Wuhan National Laboratory for Optoelectronics&School of Optical and Electronic Information Huazhong University of Science and TechnologyWuhan 430074China School of Mechanical Engineering and Electronic Information China University of GeosciencesWuhan 430074China Optics Valley Laboratory Wuhan 430074China Xidian University Xi’an 710126China

High-performance germanium photodiodes are crucial components in silicon photonic integrated circuits for large-capacity data ***,the bandwidths of most germanium photodiodes are limited by the intractable resistance–capacitance parasitic ***,we introduce a unique U-shaped electrode to alleviate this issue,reducing the parasitic effect by 36%without compromising any other ***,a large bandwidth of 103 GHz,an optical responsivity of 0.95 A/W at 1550 nm,and a dark current as low as 1.3 nA are achieved,leading to a record high specific *** is the first breakthrough to 100 GHz bandwidth among all vertical germanium photodiodes,to the best of our *** eye diagrams of 120 Gb/s on-off keying and 200 Gb/s four-level pulse amplitude signals are well *** work provides a promising solution for chip-based ultra-fast photodetection.

关键词： Gb/s shaped electrode

Reduction of unactivated alkyl chlorides enabled by light-induced single electron transfer

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第2期67卷 471-481页

作者： Lei Dai Zhao-Fei Zhang xiang-yu Chen School of Chemical Sciences University of the Chinese Academy of SciencesBeijing100049China Institute of Chemistry Chinese Academy of SciencesBeijing100190China Binzhou Institute of Technology Weiqiao-UCAS Science and Technology ParkBinzhou256606China

Alkyl chlorides are abundant and easily accessible starting ***,due to the high reduction potentials associated with unactivated alkyl chlorides,achieving their single electron reduction remains a persistent *** challenge has spurred the exploration of efficient activation methods to overcome this *** recent years,photocatalysis has emerged as a mild and potent tool for the single electron reduction of unactivated alkyl chlorides,opening up new possibilities in this *** the rapid advancements in this area,a comprehensive review that provides a conceptual understanding of this emerging field,with a specific focus on reaction design and catalytic mechanisms,would be timely and highly ***,we present an overview of various synthetic techniques for photoinduced single electron reduction of unactivated alkyl ***,we also discuss the limitations of the present methods and future directions that lie ahead in this field.

关键词： photocatalysis unactivated alkyl chlorides single electron transfer radical reactions

Probiotics intervention in colorectal cancer:From traditional approaches to novel strategies

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2024年第1期137卷 8-20页

作者： Suki Ha xiang Zhang Jun yu Institute of Digestive Disease and Department of Medicine and Therapeutics State Key Laboratory of Digestive DiseaseLi Ka Shing Institute of Health SciencesThe Chinese University of Hong KongHong Kong SARChina

The intestine harbors a large population of microorganisms that interact with epithelial cells to maintain host healthy physiological *** intestinal microbiota engage in the fermentation of non-digestible nutrients and produce beneficial metabolites to regulate host homeostasis,metabolism,and immune *** disruption of microbiota,known as dysbiosis,has been implicated in many intestinal diseases,including colorectal cancer(CRC).As the third most common cancer and the second leading cause of cancer-related death worldwide,CRC poses a significant health *** is an urgent need for novel interventions to reduce CRC incidence and improve clinical *** the intestinal microbiota has emerged as a promising approach for CRC prevention and *** research efforts in CRC probiotics primarily focus on reducing the incidence of CRC,alleviating treatment-related side effects,and potentiating the efficacy of anticancer therapy,which is the key to successful translation to clinical *** paper aims to review the traditional probiotics and new interventions,such as next-generation probiotics and postbiotics,in the context of *** underlying mechanisms of probiotic anti-cancer effects are also discussed,including the restoration of microbial composition,reinforcement of gut barrier integrity,induction of cancer cell apoptosis,inactivation of carcinogens,and modulation of host immune *** paper further evaluates the novel strategy of probiotics as an adjuvant therapy in boosting the efficacy of chemotherapy and *** all the promising findings presented in studies,the evaluation of potential risks,optimization of delivery methods,and consideration of intra-patient variability of gut microbial baseline must be thoroughly interpreted before bench-to-bedside translation.

关键词： colorectal cancer probiotics gut microbiota dysbiosis adjuvant therapy immune modulation gut barrrier

Mean field game of optimal relative investment with jump risk

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2024年第5期67卷 1159-1188页

作者： Lijun Bo Shihua Wang xiang yu School of Mathematics and Statistics Xidian UniversityXi'an 710126China School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026China Department of Applied Mathematics The Hong Kong Polytechnic UniversityHong KongChina

In this paper,we study the n-player game and the mean field game under the constant relative risk aversion relative performance on terminal wealth,in which the interaction occurs by peer *** the model with n agents,the price dynamics of underlying risky assets depend on a common noise and contagious jump risk modeled by a multi-dimensional nonlinear Hawkes *** a continuum of agents,we formulate the mean field game problem and characterize a deterministic mean field equilibrium in an analytical form under some conditions,allowing us to investigate some impacts of model parameters in the limiting model and discuss some financial ***,based on the mean field equilibrium,we construct an approximate Nash equilibrium for the n-player game when n is sufficiently *** explicit order of the approximation error is also derived.

关键词： relative performance contagious jump risk mean field game with jumps mean field equilibrium approximate Nash equilibrium

同方期刊数据库