In the context of power generation companies, vast amounts of specialized data and expert knowledge have been accumulated. However, challenges such as data silos and fragmented knowledge hinder the effective utilizati...In the context of power generation companies, vast amounts of specialized data and expert knowledge have been accumulated. However, challenges such as data silos and fragmented knowledge hinder the effective utilization of this information. This study proposes a novel framework for intelligent Question-and-Answer (Q&A) systems based on Retrieval-Augmented Generation (RAG) to address these issues. The system efficiently acquires domain-specific knowledge by leveraging external databases, including Relational Databases (RDBs) and graph databases, without additional fine-tuning for Large Language Models (LLMs). Crucially, the framework integrates a Dynamic Knowledge Base Updating Mechanism (DKBUM) and a Weighted Context-Aware Similarity (WCAS) method to enhance retrieval accuracy and mitigate inherent limitations of LLMs, such as hallucinations and lack of specialization. Additionally, the proposed DKBUM dynamically adjusts knowledge weights within the database, ensuring that the most recent and relevant information is utilized, while WCAS refines the alignment between queries and knowledge items by enhanced context understanding. Experimental validation demonstrates that the system can generate timely, accurate, and context-sensitive responses, making it a robust solution for managing complex business logic in specialized industries.展开更多
Surrogate models are commonly used for approximation of large computationally expensive vehicle crash simulation to facilitate rapid design space exploration and optimization. Unfortunately, the optimum design based o...Surrogate models are commonly used for approximation of large computationally expensive vehicle crash simulation to facilitate rapid design space exploration and optimization. Unfortunately, the optimum design based on surrogates may turn out to be infeasible after running finite element crash simulation due to the surrogate errors. To meet this challenge, conservative strategy of surrogate modeling through compensating fitting errors was used for reliability based design optimization of vehicle structures for crashworthiness and weight reduction. The critical crash responses were constructed by unbiased kriging models, and conservative surrogates were obtained via adding safety margin to estimate the crash responses conservatively. The benefits of using conservative surrogates for reliability based design optimization were investigated in the context of constraint feasibility of the optimum designs through a mathematical example and a case study on vehicle crashworthiness design. The results demonstrate that optimization based on conservative surrogate helps to achieve the feasible optimum design, showing more attractive for reliability based design optimization in engineering applications.展开更多
In ground-based GPS meteorology, Tm is a key parameter to calculate the conversion factor that can convert the zenith wet delay（ZWD） to precipitable water vapor（PWV）. It is generally acknowledged that Tm is in an ...In ground-based GPS meteorology, Tm is a key parameter to calculate the conversion factor that can convert the zenith wet delay（ZWD） to precipitable water vapor（PWV）. It is generally acknowledged that Tm is in an approximate linear relationship with surface temperature Ts, and the relationship presents regional variation. This paper employed sliding average method to calculate correlation coefficients and linear regression coefficients between Tm and Ts at every 2°× 2.5° grid point using Ts data from European Centre for Medium-Range Weather Forecasts（ECMWF） and Tm data from ＂GGOS Atmosphere＂, yielding the grid and bilinear interpolation-based Tm Grid model. Tested by Tm and Ts grid data, Constellation Observation System of Meteorology, Ionosphere, and Climate（COSMIC） data and radiosonde data, the Tm Grid model shows a higher accuracy relative to the Bevis Tm-Ts relationship which is widely used nowadays. The Tm Grid model will be of certain practical value in high-precision PWV calculation.展开更多
长江流域是我国重要的生态屏障,近几十年来,剧烈的气候变化和人类活动改变了长江流域的自然景观,并使其生态系统结构发生改变,生态系统功能退化。采用活力-组织-弹性-生态系统服务功能评价框架,在县域尺度上计算了2000~2020年长江流域...长江流域是我国重要的生态屏障,近几十年来,剧烈的气候变化和人类活动改变了长江流域的自然景观,并使其生态系统结构发生改变,生态系统功能退化。采用活力-组织-弹性-生态系统服务功能评价框架,在县域尺度上计算了2000~2020年长江流域生态系统健康指数(Ecosystem Health Index,EHI),利用空间自相关方法分析了生态系统健康的空间聚集效应,并基于最优参数地理探测器模型和地理加权回归模型揭示了驱动因素的独立效应和联合效应及驱动因素的空间变化特征。结果表明:(1)长江流域生态系统健康水平整体较好,EHI均值为0.545,中下游高于上游,南部高于北部,生态系统水平较高的地区主要分布在林地及其周围,20年间,长江流域的生态系统健康水平呈现改善趋势;(2)研究期内,长江流域生态系统健康水平呈现显著的空间集聚效应,且空间集聚程度呈现减弱趋势;(3)在驱动因子方面,影响长江流域生态系统健康的主导因素是土地利用强度和林地占比,自然因素对流域大部分区域有正向影响,社会经济因素对流域大部分地区有负向影响,且社会经济因素对长江流域生态系统健康的影响力度要大于自然因素。该研究可为长江流域生态系统的保护和管理,促进长江流域可持续协调发展提供理论参考。展开更多
Objective To investgate the value of various parameters obtained from monoexponential,biexponential,and stretched exponential diffusion-weighted imaging models in the differential diagnosis of breast lesions.Methods A...Objective To investgate the value of various parameters obtained from monoexponential,biexponential,and stretched exponential diffusion-weighted imaging models in the differential diagnosis of breast lesions.Methods A retrospective study was performed in 54 patients with pathologically confirmed malignant tumors(n=30),benign lesions(n=34)and normal fibroglandular展开更多
文摘In the context of power generation companies, vast amounts of specialized data and expert knowledge have been accumulated. However, challenges such as data silos and fragmented knowledge hinder the effective utilization of this information. This study proposes a novel framework for intelligent Question-and-Answer (Q&A) systems based on Retrieval-Augmented Generation (RAG) to address these issues. The system efficiently acquires domain-specific knowledge by leveraging external databases, including Relational Databases (RDBs) and graph databases, without additional fine-tuning for Large Language Models (LLMs). Crucially, the framework integrates a Dynamic Knowledge Base Updating Mechanism (DKBUM) and a Weighted Context-Aware Similarity (WCAS) method to enhance retrieval accuracy and mitigate inherent limitations of LLMs, such as hallucinations and lack of specialization. Additionally, the proposed DKBUM dynamically adjusts knowledge weights within the database, ensuring that the most recent and relevant information is utilized, while WCAS refines the alignment between queries and knowledge items by enhanced context understanding. Experimental validation demonstrates that the system can generate timely, accurate, and context-sensitive responses, making it a robust solution for managing complex business logic in specialized industries.
基金the National Natural Science Foundation of China (No. 50875164)
文摘Surrogate models are commonly used for approximation of large computationally expensive vehicle crash simulation to facilitate rapid design space exploration and optimization. Unfortunately, the optimum design based on surrogates may turn out to be infeasible after running finite element crash simulation due to the surrogate errors. To meet this challenge, conservative strategy of surrogate modeling through compensating fitting errors was used for reliability based design optimization of vehicle structures for crashworthiness and weight reduction. The critical crash responses were constructed by unbiased kriging models, and conservative surrogates were obtained via adding safety margin to estimate the crash responses conservatively. The benefits of using conservative surrogates for reliability based design optimization were investigated in the context of constraint feasibility of the optimum designs through a mathematical example and a case study on vehicle crashworthiness design. The results demonstrate that optimization based on conservative surrogate helps to achieve the feasible optimum design, showing more attractive for reliability based design optimization in engineering applications.
基金supported by National Natural Science Foundation of China(41301377)by the Fundamental Research Funds for the Central Universities(2014214020202)by Surveying and Mapping Basic Research Program of National Administration of Surveying,Mapping and Geoinformation(13-02-09)
文摘In ground-based GPS meteorology, Tm is a key parameter to calculate the conversion factor that can convert the zenith wet delay（ZWD） to precipitable water vapor（PWV）. It is generally acknowledged that Tm is in an approximate linear relationship with surface temperature Ts, and the relationship presents regional variation. This paper employed sliding average method to calculate correlation coefficients and linear regression coefficients between Tm and Ts at every 2°× 2.5° grid point using Ts data from European Centre for Medium-Range Weather Forecasts（ECMWF） and Tm data from ＂GGOS Atmosphere＂, yielding the grid and bilinear interpolation-based Tm Grid model. Tested by Tm and Ts grid data, Constellation Observation System of Meteorology, Ionosphere, and Climate（COSMIC） data and radiosonde data, the Tm Grid model shows a higher accuracy relative to the Bevis Tm-Ts relationship which is widely used nowadays. The Tm Grid model will be of certain practical value in high-precision PWV calculation.
文摘长江流域是我国重要的生态屏障,近几十年来,剧烈的气候变化和人类活动改变了长江流域的自然景观,并使其生态系统结构发生改变,生态系统功能退化。采用活力-组织-弹性-生态系统服务功能评价框架,在县域尺度上计算了2000~2020年长江流域生态系统健康指数(Ecosystem Health Index,EHI),利用空间自相关方法分析了生态系统健康的空间聚集效应,并基于最优参数地理探测器模型和地理加权回归模型揭示了驱动因素的独立效应和联合效应及驱动因素的空间变化特征。结果表明:(1)长江流域生态系统健康水平整体较好,EHI均值为0.545,中下游高于上游,南部高于北部,生态系统水平较高的地区主要分布在林地及其周围,20年间,长江流域的生态系统健康水平呈现改善趋势;(2)研究期内,长江流域生态系统健康水平呈现显著的空间集聚效应,且空间集聚程度呈现减弱趋势;(3)在驱动因子方面,影响长江流域生态系统健康的主导因素是土地利用强度和林地占比,自然因素对流域大部分区域有正向影响,社会经济因素对流域大部分地区有负向影响,且社会经济因素对长江流域生态系统健康的影响力度要大于自然因素。该研究可为长江流域生态系统的保护和管理,促进长江流域可持续协调发展提供理论参考。
文摘Objective To investgate the value of various parameters obtained from monoexponential,biexponential,and stretched exponential diffusion-weighted imaging models in the differential diagnosis of breast lesions.Methods A retrospective study was performed in 54 patients with pathologically confirmed malignant tumors(n=30),benign lesions(n=34)and normal fibroglandular
