检索结果-南通市图书馆

Strategies to Improve CT Dose Optimization for Hybrid PET/CT Imaging

Open Journal of Medical Imaging 2021年第2期11卷 48-57页

作者： Abdel-Baset Bani Yaseen Yasmin Md Radzi Hussain M. Almohiy akshay kohli Mohammad Rawashdeh Faculty of Applied Medical Sciences Jordan University of Science and Technology Irbid Jordan School of Physics Universiti Sains Malaysia Penang Malaysia Department of Radiological Sciences College of Applied Medical Sciences King Khalid University Abha Saudi Arabia Department of Radiology John Hunter Hospital New Lambton Heights Australia

Background: To evaluate whether current dose reduction strategies for the CT component of hybrid Positron Emission Tomography—Computed Tomography (PET/CT) systems could reduce patient dose with maintaining adequate image quality for PET/CT studies. Materials and Methods: Literature survey was initially based on the selection of keywords and years of publication to identify potentially relevant articles, then the further search was conducted on the authors and references from these articles. The abstract of each article was first appraised to decide whether the content was relevant to this research question. The articles were classified into five groups: studies on dosimetry, studies on radiation-induced diseases, studies on dose reduction methods for CT-based attenuation correction (CTAC), studies on dose reduction methods for CT localization, and studies on reducing the need for a full-dose diagnostic CT in PET/CT imaging. 58 peer-reviewed articles were selected and appraised and 29 articles were used to compose this literature review. Results: The published nuclear medicine and medical physics literature were reviewed. CT dose contributed 47% - 81% of the total effective dose of a standard PET/CT study and was associated with radiation-induced diseases. The dose reduction techniques were extracted and divided into three categories: reducing the CT dose for attenuation correction (AC) and localization, selectively localizing CT use, and reducing the need for a full-dose diagnostic CT. Conclusion: Three strategies have been demonstrated, with high potential for reducing patient dose while maintaining an adequate CT image quality, used for CTCA localization and diagnosis, respectively.

关键词： CT Scan Radiation Dose Hybrid Imaging PET Systems CTAC

来源：

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

Reliability assessment of deep excavations in spatially random cohesion weakening friction strengthening massive rocks:Application to nuclear repositories

引用

Underground Space 2023年第6期13卷 48-73页

作者： akshay Kumar Gaurav Tiwari Department of Civil Engineering Indian Institute of Technology KanpurKanpurUttar Pradesh 208016India

An augmented methodology is developed to estimate the reliability of deep excavations along spatially variable massive rock masses using the cohesion weakening friction strengthening(CWFS)*** parameters of the CWFS model were initially identified using Sobol’s global sensitivity analysis based on their influence on the displacements and excavation damage zone around *** probability of failure was estimated by performing Mont–Carlo Simulations on random finite difference models of excavations generated via MATLAB-FLAC2D coupling,considering the spatial variation of these sensitive *** variation was modeled by generating anisotropic random fields of sensitive CWFS parameters via the recently developed Fourier series method and updated correlations suggested by Walton(2019).The proposed methodology was demonstrated for a proposed deep nuclear waste repository to be located in *** from the developed methodology were systematically compared with those of traditional reliability(ignoring spatial variation)and deterministic methods(ignoring uncertainty).Although the developed methodology was computationally complex,it was judged to be the most realistic due to the realistic consideration of heterogeneous distributions of rock *** methodologies underestimate/overestimate the excavation performance due to negligence of uncertainty and spatial ***,a parametric analysis was performed using developed methodology by varying the initial friction angle,scale of fluctuations(SOFs)and dilation *** effect of initial friction angle was observed to be more pronounced on the probability of failures as compared to SOFs and dilation *** observations were made related to the excavation damage zone(EDZ)development quantified using yield area ratio.

关键词： Deep excavations Brittle failures CWFS model Sobol’s sensitivity Moving least square response surface Fourier series random field

来源：

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

Molecular design with automated quantum computing-based deep learning and optimization

引用

npj Computational Materials 2023年第1期9卷 861-874页

作者： akshay Ajagekar Fengqi You Systems Engineering Cornell UniversityIthacaNY 14853USA Robert Frederick Smith School of Chemical and Biomolecular Engineering Cornell UniversityIthacaNY 14853USA

Computer-aided design of novel molecules and compounds is a challenging task that can be addressed with quantum computing(QC)owing to its notable advances in optimization and machine ***,we use QC-assisted learning and optimization techniques implemented with near-term QC devices for molecular property prediction and generation *** proposed probabilistic energy-based deep learning model trained in a generative manner facilitated by QC yields robust latent representations of molecules,while the proposed data-driven QC-based optimization framework performs guided navigation of the target chemical space by exploiting the structure–property relationships captured by the energy-based *** demonstrate the viability of the proposed molecular design approach by generating several molecular candidates that satisfy specific property target *** proposed QC-based methods exhibit an improved predictive performance while efficiently generating novel molecules that accurately fulfill target conditions and exemplify the potential of QC for automated molecular design,thus accentuating its utility.

关键词： automated computing optimization

来源：

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

＂NEW＂ resource recovery from wastewater using bioelectrochemical systems： Moving forward with functions

引用

Frontiers of Environmental Science & Engineering 2018年第4期12卷 3-15页

作者： akshay Jain Zhen He Department of Civil and Environmental Engineering Virginia Polytechnic Institute and State University Blacksburg VA 24061 USA

Bioelectrochemical systems （BES） have been extensively studied ｜br resource recovery from wastewater. By taking advantage of interactions between microorganisms and electrodes, BES can accomplish wastewater treatment while simultaneously recovering various resources including nutrients, energy and water （＂NEW＂）. Despite much progress in laboratory sit, dies, BES have not been advanced to practical applications. This paper aims to provide some subjective opinions and a concise discussion of several key challenges in BES-based resource recovery and help identil- the potential application niches that may guide further technological development. In addition to further increasing recovery efficiency, it is also important to have more lbcus on the applications of the recovered resources such as how to use the harvested electricity and gaseous energy and how to separate the recovered nutrients in an energy-efficient way. A changc in mindset fur energy performance of BES is necessary to understand overall energy production and consumption. Scaling up BES can go through laboratory scale, transitional scale, and then pilot scale. Using functions as driving forces lbr BES research and development will better guide the investment of efforts.

关键词： Bioelectrochemical systemsResource recoveryWastewater treatmentEnergy Nutrients

来源：

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

A Novel Process of CO_(2) Reduction and CO_(2) Sequestration Through an Innovative Accelerated Carbonation Technique

引用

Journal of Wuhan University of Technology(Materials Science) 2023年第5期38卷 1105-1117页

作者： akshay Ramesh Bura B Kondraivendhan Department of Civil Engineering Sardar Vallabhbhai National Institute of TechnologySuratGujaratIndia 395007

The efiect of an innovative accelerated carbonation curing technique was evaluated on concrete containing natural zeolite powder and fine aggregate as partial replacement to alleviate the CO_(2) emission up to a certain extent from the concrete production industry and improve sequestration of CO_(2) into the concrete matrix in a stable *** accelerated carbonation curing was accomplished by subjecting the concrete specimens to 0.5 and 0.75 M concentrations of sodium bicarbonate(NaHCO_(3)) solutions up to a curing age of 180 days after the initial 28 days of normal water *** for carbonation depth,pH value,compressive strength,calcium carbonate(CaCO_(3))content,X-ray difiraction,and thermogravimetric(TGA)analyses and Fourier transform infrared spectroscopy(FTIR)were performed to measure the extent of *** obtained results showed an increment in average compressive strength for the zeolite concrete(ZLC)mixes exposed to accelerated carbonation *** ZLC mixes exposed to increasing NaHCO_(3) solution concentration and exposure period exhibited greater carbonation depth and decreased pH at each depth interval indicating higher CO_(2) sequestration within the concrete *** results obtained from the microstructural analysis(XRD,TGA,and FTIR)and CaCO_(3) content measurements confirm that the higher amount of CaCO_(3) formation provides a clear indication of the carbonation enhancement and CO_(2) sequestration within the concrete matrix and in turn contributing to the global warming reduction.

关键词： CO_(2)sequestration accelerated carbonation natural zeolite calcium carbonate

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Bayesian multi-model inference methodology for imprecise momentindependent global sensitivity analysis of rock structures

引用

Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 840-859页

作者： akshay Kumar Gaurav Tiwari Department of Civil Engineering Indian Institute of Technology(IIT)KanpurKanpur208016India

Traditional global sensitivity analysis(GSA)neglects the epistemic uncertainties associated with the probabilistic characteristics(*** of distribution type and its parameters)of input rock properties emanating due to the small size of datasets while mapping the relative importance of properties to the model *** paper proposes an augmented Bayesian multi-model inference(BMMI)coupled with GSA methodology(BMMI-GSA)to address this issue by estimating the imprecision in the momentindependent sensitivity indices of rock structures arising from the small size of input *** methodology employs BMMI to quantify the epistemic uncertainties associated with model type and parameters of input *** estimated uncertainties are propagated in estimating imprecision in moment-independent Borgonovo’s indices by employing a reweighting approach on candidate probabilistic *** proposed methodology is showcased for a rock slope prone to stress-controlled failure in the Himalayan region of *** proposed methodology was superior to the conventional GSA(neglects all epistemic uncertainties)and Bayesian coupled GSA(B-GSA)(neglects model uncertainty)due to its capability to incorporate the uncertainties in both model type and parameters of *** Borgonovo’s indices estimated via proposed methodology provide the confidence intervals of the sensitivity indices instead of their fixed-point estimates,which makes the user more informed in the data collection *** performed with the varying sample sizes suggested that the uncertainties in sensitivity indices reduce significantly with the increasing sample *** accurate importance ranking of properties was only possible via samples of large ***,the impact of the prior knowledge in terms of prior ranges and distributions was significant;hence,any related assumption should be made carefully.

关键词： Bayesian inference Multi-model inference Statistical uncertainty Global sensitivity analysis(GSA) Borgonovo’s indices Limited data

来源：

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

Jackknife based generalized resampling reliability approach for rock slopes and tunnels stability analyses with limited data:Theory and applications

引用

Journal of Rock Mechanics and Geotechnical Engineering 2022年第3期14卷 714-730页

作者： akshay Kumar Gaurav Tiwari Department of Civil Engineering IIT KanpurIndia

An efficient resampling reliability approach was developed to consider the effect of statistical uncertainties in input properties arising due to insufficient data when estimating the reliability of rock slopes and *** approach considers the effect of uncertainties in both distribution parameters(mean and standard deviation)and types of input ***,the approach was generalized to make it capable of analyzing complex problems with explicit/implicit performance functions(PFs),single/multiple PFs,and correlated/non-correlated input *** couples resampling statistical tool,***,with advanced reliability tools like Latin hypercube sampling(LHS),Sobol’s global sensitivity,moving least square-response surface method(MLS-RSM),and Nataf’s *** developed approach was demonstrated for four cases encompassing different *** were compared with a recently developed bootstrap-based resampling reliability *** results show that the approach is accurate and significantly efficient compared with the bootstrap-based *** proposed approach reflects the effect of statistical uncertainties of input properties by estimating distributions/confidence intervals of reliability index/probability of failure(s)instead of their fixed-point ***,sufficiently accurate results were obtained by considering uncertainties in distribution parameters only and ignoring those in distribution types.

关键词： Statistical uncertainty Resampling reliability Moving least square response surface(MLSRSM) Sobol’s global sensitivity Correlation coefficient

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Learning Convex Optimization Models

引用

IEEE/CAA Journal of Automatica Sinica 2021年第8期8卷 1355-1364页

作者： akshay Agrawal Shane Barratt Stephen Boyd Department of Electrical Engineering Stanford UniversityStanfordCA 94305 USA

A convex optimization model predicts an output from an input by solving a convex optimization *** class of convex optimization models is large,and includes as special cases many well-known models like linear and logistic *** propose a heuristic for learning the parameters in a convex optimization model given a dataset of input-output pairs,using recently developed methods for differentiating the solution of a convex optimization problem with respect to its *** describe three general classes of convex optimization models,maximum a posteriori(MAP)models,utility maximization models,and agent models,and present a numerical experiment for each.

关键词： Convex optimization differentiable optimization machine learning

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Data Centric Design:A New Approach to Design of Microstructural Material Systems

引用

Engineering 2022年第3期8卷 89-98页

作者： Wei Chen akshay Iyer Ramin Bostanabad Department of Mechanical Engineering Northwestern UniversityEvanstonIL 60208USA Department of Mechanical and Aerospace Engineering University of CaliforniaIrvineCA 92697USA

Building processing,structure,and property(PSP)relations for computational materials design is at the heart of the Materials Genome Initiative in the era of high-throughput computational materials *** technological advancements in data acquisition and storage,microstructure characterization and reconstruction(MCR),machine learning(ML),materials modeling and simulation,data processing,manufacturing,and experimentation have significantly advanced researchers’abilities in building PSP relations and inverse material *** this article,we examine these advancements from the perspective of design *** particular,we introduce a data-centric approach whose fundamental aspects fall into three categories:design representation,design evaluation,and design *** in each of these aspects are guided by and benefit from domain ***,for each aspect,we present a wide range of computational methods whose integration realizes data-centric materials discovery and design.

关键词： Materials informatics Machine learning Microstructure Reconstruction Bayesian optimization Mixed-variable modeling Dimension reduction Materials design

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Direct optical-structure correlation in atomically thin dichalcogenides and heterostructures

引用

Nano Research 2020年第5期13卷 1363-1368页

作者： akshay Singh Hae Yeon Lee Silvija Gradcak Department of Materials Science and Engineering Massachusetts Institute of Technology77 Massachusetts AveCambridgeMA 02141USA

Atomically thin transition metal dichalcogenides(TMDs)have distinct opto-electronic properties including enhanced luminescence and high on-off current ratios,which can be further modulated by making more complex TMD ***,resolution limits of conventional optical methods do not allow for direct nanoscale optical-structural correlation measurements in these materials,particularly of buried interfaces in TMD *** we use,for the first time,electron beam induced cathodoluminescence in a scanning transmission electron microscope(CL-STEM)to measure optical properties of monolayer TMDs(WS2,MoS2 and WSSe alloy)encapsulated between layers of *** observe dark areas resulting from localized(~100 nm)imperfect interfaces and monolayer folding,which shows that the intimate contact between layers in this application-relevant heterostructure is required for proper inter layer *** also realize a suitable imaging method that minimizes electron-beam induced changes and provides measurement of intrinsic *** overcome the limitation of small electron interaction volume in TMD monolayer(and hence low photon yield),we find that encapsulation of TMD monolayers with hBN and subsequent annealing is ***-STEM offers to be a powerful method to directly measure structure-optical correspondence in lateral or vertical heterostructures and alloys.

关键词： cathodoluminescence two-dimensional(2D)materials transition metal dichalcogenides interfaces heterostructures

来源：

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

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：