检索结果-南通市图书馆

A serialized civil aircraft R&D cost estimation model considering commonality based on BP algorithm

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第4期35卷 253-265页

作者： Yongjie ZHANG Kang CAO Ke LIANG Yongqi ZENG wenjun dong School of Aviation.Northwestern Polytechnical University Xi'an 710072China Shanghai Aircraft Design and Research Institute Shanghai 201210China

The common design of serial civil aircraft, an important strategy of modern civil aircraft research and develop-ment, minimizes the whole life cycle cost of civil aircraft through asset reuse and resource sharing. However, the existing estimating model for the R&D cost of civil aircraft ignores the effects of common design, so the value estimated by estimating derivative models is significantly inconsistent with the actual one. To solve this problem, a novel assessment method for civil aircraft commonality indicators is developed based on fuzzy set in the present study, exploiting the attributes and structural parameters of the aircraft to be assessed as input to determine the degree of membership that pertains to the commonality sub-interval as the commonality *** the BP(Back Propagation) neural network algorithm is adopted to establish the relationship between the common index and the decrease rate of the R&D cost of derivative models. The model employs over a dozen typical civil aircraft models(e.g., Boeing, Airbus, and Bombardier) as the sample data for network learning training to build a mature neural network model for estimating the R&D cost of novel derivative models. As revealed from the comparative analysis on the calculated results of the samples, the estimated results of the model given the effects of commonality in the present study exhibit higher estimation accuracy and value for future work.

关键词： BP algorithm Civil aircraft R&D cost Common indicators Fuzzy set Serialized civil aircraft

Exploration and implementation of commonality valuation method in commercial aircraft family design

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2019年第8期32卷 1828-1846页

作者： Yongjie ZHANG Zheng YANG Xianchao MA wenjun dong Dayong dong Zhaoguang TAN Shuai ZHANG School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Shanghai Aircraft Design and Research Institute Shanghai 200232China Beijing Aeronautical Science&Technology Research Institute Beijing 102211China

Commercial aircraft family design can reduce development costs, shorten development cycles, and expand the market coverage of aircraft. Commercial aircraft family development has become one of the most important features of modern aircraft design. This paper explores the effects of commonality on different aircraft models in a commercial aircraft family. The existing product commonality indexes are summarized and their limitations in the application to aircraft design are discussed. Then a new component commonality index is proposed based on the component decomposition structure. A model for calculating the aircraft program value is established,which considers development costs, manufacturing costs, sale price, operation costs and residual costs. The effects of aircraft commonality on time and economic costs of both development and manufacturing, and on sale price, are analyzed and quantified. The commonality evaluation strategy is obtained, which features comprehensive consideration of the aircraft program value and time costs. The break-even analysis of aircraft is proceeded on the basis of costs and price data. By using a real option method, the strategy considers the uncertainty of the aircraft program and the flexibility of the manufacturer. This strategy proves to be rational and applicable to aircraft design based on the calculation of three examples and the analysis of parameter sensitivity.

关键词： Aircraft cost Aircraft family Aircraft program value Commonality index Real option method

High-performance electrocatalyst of vanadium-iron bimetal organic framework arrays on nickel foam for overall water splitting

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2021年第7期32卷 2263-2268页

作者： Liang Han Jie Xu Ya Huang wenjun dong Xilai Jia Beijing Key Laboratory of Function Materials for Molecule & Structure Construction School of Materials Science and EngineeringUniversity of Science and Technology Beijing

The development of active,low-cost and durable bifunctional electrocatalysts toward both oxygen evolution reaction（OER） and hydro gen evolution react ion（HER） a re important for overall water ***,well-defined arrays of vanadium-iron bimetal organic frameworks（VFe-MOF） with controllable stoichiometry have been successfully prepared on nickel foam（NF）.The as-fabricated VFe-MOF@NF electrode exhibits excellent electrocatalytic activity and durability for OER and HER in alkaline *** material's overpotentials of 10 mA/cm2are 246 mV for OER and 147 mV for HER,*** electrolyzer made from the VFe-MOF@NF electrodes as both the cathode and anode in 1 mol/L KOH needs only a voltage of 1.61 V to reach a current density of 10 mA/*** superior performance of VFeMOF@NF can be attributed to the morphological control and electronic regulation of the bimetals,that is,1) the exposure of the active sites at electrocatalyst/electrolyte interfaces due to the array structure;2)the synergistic effect of vanadium and iron metals on electro-catalyzing the overall water splitting.

关键词： Bimetal organic framework Array Overall water splitting Oxygen evolution reaction Hydrogen evolution reaction

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

决策树分类法在遥感图像处理中的应用

电子技术（上海） 2024年第6期53卷 40-41页

作者：王刚王俊周箭董文军北京市遥感信息研究所北京101318

阐述决策树分类法在遥感图像处理中的应用和潜力,以及决策树分类在遥感图像处理中的实践,包括数据收集和处理、特征提取和选择、模型构建和训练。

关键词：决策树分类法遥感图像处理特征提取模型训练

Controllable synthesis and surface modification of molybdenum oxide nanowires: a short review

在线全文

学校读者我要写书评

暂无评论

Tungsten 2019年第4期1卷 258-265页

作者： Dimberu G.Atinafu wenjun dong Minggang Du School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Science and Technology On Vehicle Transmission Laboratory China North Vehicle InstituteBeijing 100072China

Transition metal oxides are found to have overwhelming applications in energy,electronics,catalytic,and bio-and micromechanical systems.A recent report emphasized the current advancements in molybdenum oxide(MoO_(x))nanowire synthesis and the corresponding surface-functionalized nanostructured materials based on our previously reported *** preparation of the nanowires and their applications were systematically ***_(x) nanowires combined with substrates exhibited remarkable performances for high energy storage and power densities with high *** addition,the review concluded the future advancements of MoO_(x) nanowires.

关键词： Molybdenum oxide nanowire Controllable synthesis Surface modification

Decorating cobalt phosphide and rhodium on reduced graphene oxide for high-efficiency hydrogen evolution reaction

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

Journal of Energy Chemistry 2019年第7期28卷 72-79页

作者： Haiyan Zheng Xiubing Huang Hongyi Gao wenjun dong Guilong Lu Xiao Chen Ge Wang Beijing Key Laboratory of Function Materials for Molecule & Structure Construction School of Materials Science and Engineering University of Science and Technology Beijing

Electrochemical reduction of water to hydrogen holds great promise for clean energy,while its widespread application relies on the development of efficient catalysts with large surface area,abundant exposed active sites and superior electron ***,we report a facile strategy to configure an electrocatalyst composed of cobalt phosphide and rhodium uniformly anchored on reduced graphene oxide for hydrogen *** hybrids effectively integrate the exposed active sites,electron conductivity and synergistic effect of the *** tests exhibit that the catalyst shows superior hydrogen evolution reaction catalytic activity and stability,with a small Tafel slope of 43 m V *** as low as 29 and 72 mV are required to achieve current densities of 2 and 10 mA cm-2in 0.5M H2SO4,*** hybrid constitution with highly active sites on conductive substrate is a new strategy to synthesize extremely efficient ***,the efficient synergistic effect among cobalt phosphide,rhodium and reduced graphene oxide provides a novel approach for configuring electrocatalysts with high electron efficiency.

关键词： Reduced graphene oxide Cobalt phosphide Hydrogen evolution reaction Electrocatalysts Synergistic effect

Synthesis methods and powder quality of titanium monocarbide

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第8期72卷 10-18页

作者： Maoqiao Xiang wenjun Ding Qinghua dong Qingshan Zhu State Key Laboratory of Mesoscience and Engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of the Chinese Academy of SciencesBeijing 100049China Innovation Academy for Green Manufacture Chinese Academy of SciencesBeijing 100190China

Titanium monocarbide(TiC),which is the most stable titanium-based carbide,has attracted considerable interest in the fields of energy,catalysis,and structural materials due to its excellent *** of high-quality TiC powders with low cost and high efficiency is crucial for industrial applications;however major challenges face its ***,the methods for synthesizing TiC powders based on a reaction system are *** analysis is focused on the underlying mechanisms by which synthesis methods affect the quality of ***,strategies for improving the synthesis of highquality powders are analyzed from the perspective of enhancing heat and mass transfer ***,the critical issues,challenges,and development trends of the synthesis technology and application of high-quality TiC powder are discussed.

关键词： Titanium carbide Synthesis methods Reaction engineering Reaction kinetics Powder technology

UPLC-MS/MS测定羊奶和羊奶粉中安乃近残留量

在线全文

学校读者我要写书评

暂无评论

食品工业 2024年第2期45卷 288-292页

作者：李璐杨家秀王聪董文君张艳富平县检验检测中心(陕西省羊乳产品质量监督检验中心) 富平711700 陕西圣唐乳业有限公司富平711700

建立超高效液相色谱-质谱联用法测定羊奶和羊奶粉中安乃近(4-氨基安替比林、4-甲酰氨基安替比林、4-乙酰氨基安替比林和4-甲基氨基安替比林)残留量的分析方法。样品经乙腈提取,氮吹浓缩,以甲酸水和甲酸乙腈作为流动相,通过超高效液相色... 详细信息

建立超高效液相色谱-质谱联用法测定羊奶和羊奶粉中安乃近(4-氨基安替比林、4-甲酰氨基安替比林、4-乙酰氨基安替比林和4-甲基氨基安替比林)残留量的分析方法。样品经乙腈提取,氮吹浓缩,以甲酸水和甲酸乙腈作为流动相,通过超高效液相色谱,采用ESI正离子模式多反应监测,4-氨基安替比林、4-甲酰氨基安替比林、4-乙酰氨基安替比林用外标法定量,4-甲基氨基安替比林用同位素内标定量。4-氨基安替比林在0~99.1μg/L范围内,其他3个化合物在0~99.9μg/L范围内的线性关系良好,相关系数R2均大于0.995。4-氨基安替比林、4-甲酰氨基安替比林、4-乙酰氨基安替比林和4-甲基氨基安替比林的定量限分别为2.8,3.9,0.088和1.4μg/kg。当羊奶加标水平约5,10,20和50μg/kg,羊奶粉约40,80,160和400μg/kg时,回收率为83.6%~100.2%,方法的精密度相对标准偏差为0.3%~6.5%(n=6)。该方法灵敏、准确,能够快速、有效检测羊奶和羊奶粉中安乃近残留量,可用于日常风险监测和市场监管。

关键词：安乃近羊奶羊奶粉超高效液相色谱-质谱联用(UPLC-MS/MS)

A simple approach to porous low-temperature-sintering BaTiO_3

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2012年第9期55卷 1765-1769页

作者： LI Yang LIU Hu LIU FaJia LI ChaoRong CHEN BenYong dong wenjun Center for Optoelectronics Materials and Devices Center for Nanoscience and NoanotechnologyKey Laboratory of Advanced TextileMaterials and Manufacturing TechnologyMinistry of EducationEngineering Research Center for Eco-Dying&Finishing of TextilesZhejiang Sci-Tech UniversityHangzhou 310018China

Porous tetragonal BaTiO 3 ceramic was successfully prepared by a combination of hydrothermal and low-temperature-sintering *** hollow TiO2@BaCO 3 as the sintering precursor was synthesized via a simple hydrothermal method,and then porous BaTiO 3 was generated by calcining the hollow TiO2@BaCO 3 precursor at 900 ℃ without *** hollow TiO2@BaCO 3 structure plays two important roles in the preparing of the porous BaTiO 3 ***,the TiO2@BaCO 3 hollow structure provides high surface areas and increases the contact points between BaCO 3 and TiO2,which can reduce the sintering temperature of the BaTiO 3 ***,the cavity of the ordered arranged TiO2@BaCO 3 hollow sphere shows important influence on the porous structure,and the pore size of the as-prepared porous BaTiO 3 ceramic can be tuned from several nanometers to hundreds nanomters by changing the sintering *** formation mechanism of the porous BaTiO 3 ceramic was proposed.

关键词： BaTi03 ceramics sintering porosity