检索结果-南通市图书馆

Ca2+ cation-mediated microenvironment for electrochemical hydrodimerization of furfural

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年

作者： wei Du Shuangshuang cha Can Lei Mengxin Qu Zhongqiang Deng Ming Gong Xinhe Bao Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Fudan University State Key Laboratory of Catalysis National Laboratory for Clean Energy Collaborative Innovation Center of Chemistry for Energy Materials Dalian Institute of Chemical Physics Chinese Academy of Sciences

Furfural is one of the most important biomass-based platform molecules as sustainable precursors for chemicals and fuels. The electrochemical hydrodimerization of furfural can generate hydrofuroin, which is a promising precursor for gasoline or jet ***, steering the selectivity toward hydrodimerization under near-neutral conditions that suppress polymerization and disproportionation of furfural remains challenging. Herein, we discovered that tuning the electrolyte cations could be an effective and alternative strategy for modulating furfural reduction to the traditional electrocatalyst design. Under the optimal Ca2+cations,hydrofuroin yield could be much improved from other cations with hydrofuroin selectivity of 95.5%. The systematic characterization of the ion-centered double layer reflected the suitable sizes and charges of hydrated Ca2+for suppressing the hydrogen evolution reaction from activation of surrounding water molecules as well as encouraging furfural accumulation via non-covalent interaction for directing the electron transfer to furfurals. Ions with smaller or larger sizes can either activate local water molecules or form a crowded ionic interface that casts an adverse effect on furfural enrichment. This work not only presents an effective strategy for facilitating biomass valorization via hydrodimerization but also emphasizes the essential role of the ion-centered microenvironment for steering the electrocatalytic pathways.

关键词：

Transportation and sealing pattern of the temporary plugging ball at the spiral perforation in the horizontal well section

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2024年第5期21卷 3288-3297页

作者： Qing-Hai Hu Wan Cheng Zun-cha Wang Yu-Zhao Shi guang-Liang Jia Faculty of Engineering China University of GeosciencesWuhan430074HubeiChina Sinopec North China Oilfield Service Corporation Zhengzhou445007HenanChina

Multistage fracturing of horizontal wells is a critical technology for unconventional oil and gas reservoir stimulation. Ball-throwing temporary plugging fracturing is a new method for realizing uniform fracturing along horizontal wells and plays an important role in increasing oil and gas production. However,the transportation and sealing law of temporary plugging balls(TPBs) in the perforation section of horizontal wells is still unclear. Using COMSOL computational fluid dynamics and a particle tracking module, we simulate the transportation process of TPBs in a horizontal wellbore and analyse the effects of the ball density, ball diameter, ball number, fracturing fluid injection rate, and viscosity on the plugging efficiency of TPB transportation. This study reveals that when the density of TPBs is close to that of the fracturing fluid and a moderate diameter of the TPB is used, the plugging efficiency can be substantially enhanced. The plugging efficiency is greater when the TPB number is close to twice the number of perforations and is lower when the number of TPBs is three times the number of *** the fracturing fluid injection rate from low to high can control the position of the TPBs,improving plugging efficiency. As the viscosity of the fracturing fluid increases, the plugging efficiency of the perforations decreases near the borehole heel and increases near the borehole toe. In contrast, the plugging efficiency of the central perforation is almost unaffected by the fracturing fluid viscosity. This study can serve as a valuable reference for establishing the parameters for temporary plugging and fracturing.

关键词： Temporary plugging ball Horizontal well Multistage fracturing Spiral perforation Numerical simulation

Investigation of hot jet on active control of oblique detonation waves

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2020年第3期33卷 861-869页

作者： Hongbin LI Jianling LI cha XIONG wei FAN Lei ZHAO Wenhu HAN School of Power and Energy Northwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of Internal Aerodynamics in Aero-Engine Xi’an 710072China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

The hot jet injection is utilized to actively control the oblique detonation wave,such as initiating and stabilizing an oblique detonation wave at a desired position that is shorter than the length of induction zone,and adjust the height of the oblique detonation wave at the exit of combustor when the oblique detonation wave engine is working on off-design flight *** fifth order weighted Essentially Non-Oscillatory(WENO)scheme and a two-step reversible reaction mechanism of the stoichiometric H_2/Air are adopted in the *** the help of hot jet injection,the transition from inert oblique shock wave to the oblique detonation wave immediately occurs near the position of hot jet injection,and consequently the length of combustor can be *** angle of oblique detonation wave also decreases as the hot jet injection approaches the nose of ***,the height of the oblique detonation wave at the exit of combustor can be flexibly adjusted,and also depends on the injection position and the strength of the hot *** the velocity of the hot jet is too weak to directly trigger the overall oblique detonation wave at the position of injection,increasing the injection pressure will improve the strength of the hot jet and results in a successful transition.

关键词： Active control Hot jet Numerical simulation Oblique detonation wave Supersonic propulsion

A Modified Differential Transform Method (DTM) for Analyzing Irreversibility of Heat Transfer in Flow Through a Moving Plate with Variable Temperature

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2017年第11期67卷 647-653页

作者： Yin-wei Lin Kuei-Hao chang cha'o-Kuang Chen Department of Mathematics and Finance Putian University Research and Services Headquarters and Technology Transfer and Business Incubation Center National Cheng Kung University Department of Mechanical Engineering National Cheng Kung University

In this paper, the entropy generation of a flow through a movable plate with variable temperature is *** similarity variables are applied to transform the local entropy generation rate to entropy generation number.A modified differential transform method(DTM) with shooting method is used to obtain the similarity solution of the entropy generation. The effects of different parameters(Prandtl number, variable wall temperature) on the irreversibility(such as N_(sh), N_(sf), N_(sx)) are analyzed and discussed. Moreover, it is worth mentioning that DTM is of advantage because its numerical solution is differentiation and integration. Therefore, its analysis result is reliable and high accuracy.

关键词： sakiadis entropy generation irreversibility moving plate differential transform DTM

Near Homogeneous Microphysics of the Record-Breaking 2020 Summer Monsoon Rainfall during the Northward Migration over East China

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2023年第10期40卷 1783-1798页

作者： Long WEN wei ZHANG cha YANG Gang CHEN Yajun HU Hao ZHANG Xichang Satellite Launch Center Xichang 615000China Xiamen Key Laboratory of Strait Meteorology Xiamen 361012China Key Laboratory of Transportation Meteorology of China Meteorological Administration Nanjing Joint Institute for Atmospheric SciencesNanjing 210041China Xiangan Meteorological Bureau Xiamen 361103China

Knowledge of the raindrop size distribution(DSD)is crucial for disaster prevention and *** recordbreaking rainfall in the summer of 2020 caused some of the worst flooding ever experienced in *** study uses 96 Parsivel disdrometers and eight-year Global Precipitation Measurement(GPM)satellite observations to reveal the microphysical aspects of the disastrous rainfall during its northward migration over East *** results show that the nearly twice as heavy rainfall in Jiangsu Province compared to Fujian Province can be attributed to the earlier-than-average northward jump of the summer monsoon rainband to the Yangtze-Huaihe River *** persistent heavy monsoon rainfall showed similar near-maritime DSD characteristics,with a higher concentration of small raindrops than the surrounding climatic *** the northward movement of the rainband,the DSD variables and composite spectra between the pre-summer rainfall in Fujian and mei-yu rainfall in Jiangsu exhibited inherent similarities with slight regional *** are associated with similar statistical vertical precipitation structures for both convective and stratiform rain in these regions/*** vertical profiles of radar reflectivity and DSD parameters are typical of monsoonal rainfall features,implying the competition between coalescence,breakup,and accretion of vital warm rain *** study attributes the anomalously long duration of the mei-yu season for the record-breaking rainfall and reveals inherent homogeneous rainfall microphysics during the northward movement of the summer monsoon *** conclusion is statistically robust and would be helpful for accurate precipitation estimation and model parameterization of summer monsoon rainfall over East China.

关键词： precipitation microphysics raindrop size distribution mei-yu East China

Short-term effects of organic amendments on soil fertility and root growth of rubber trees on Hainan Island, China

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2020年第6期31卷 2137-2144页

作者： Yanyan Huang Yudan Jing Meirong Bei Hongzhu Yang Zhengzao cha Qinghuo Lin wei Luo Rubber Research Institute CATAS/Soil and Fertilizer Research CenterCATASDanzhou 571737HainanPeople’s Republic of China

Rubber[Hevea brasiliensis(*** ***.)Mü***.]plantations are the largest cultivated forest type in tropical *** organic materials to the soil will help to maintain the quality and growth of rubber *** many studies have demonstrated that organic waste materials can be used to improve soil fertility and structure to promote root growth,few studies have studied the eff ects of organic amendments on soil fertility and root growth in rubber tree ***,bagasse,coconut husk or biochar were applied with a chemical fertilizer to test their eff ects on soil properties after 6 months and compared with the eff ects of only the chemical *** showed that the soil organic matter content,total nitrogen,available phosphorus and available potassium after the chemical fertilizer(F)treatment were all signifi cantly lower than after the chemical fertilizer+bagasse(Fba),chemical fertilizer+coconut husk(Fco)or chemical fertilizer+biochar(Fbi)(pchar increased soil fertility and promoted root growth of rubber trees in the short ***,bagasse and coconut husk were more eff ective than biochar in improving root growth of rubber trees.

关键词： Organic waste Root development Rubber tree Soil fertility

A theoretical and 1-D numerical investigation on a valve/valveless air-breathing pulse detonation engine

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2021年第1期34卷 68-78页

作者： Hua QIU cha XIONG Jianling LI School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

The important operating characteristics of pulsed Pressure Gain Combustion(PGC)propulsion are the pressure gain of the combustor component and the propulsive performance gain of the engine.A ramjet-type valve/valveless air-breathing pulsed detonation engine with a supersonic internal compression inlet is *** on an ideal thermal cycle,the ideal equivalent pressure ratios(pcb)of the Pulsed Detonation Combustor(PDC)are obtained theoretically which are directly related with the propulsive performance of the *** introducing an orifice loss model into the cycles,the critical pressure drop ratios through the orifice for the PDC achieving pressure gain and the engine achieving thrust gain are *** influencing factors are investigated by the use of a one-dimensional(1-D)numerical simulation *** operating characteristics of the pulse detonation engine are investigated with changes of the valve type,the inlet/outlet area ratio of the PDC,the nozzle area ratio,and flight *** these factors can affect pcbof the PDC,and pcbcan be optimized by changing the geometry of the *** most important influence parameter is the valve *** using an orifice-type aerodynamic valve,simulation results show that the PDC cannot achieve the pressure gain *** a supersonic internal compression inlet is introduced to the engine,whether the Pulse Detonation Engine(PDE)can achieve thrust gain comparable with that of an ideal Brayton cycle engine not only is related to the pressure gain of the combustor,but also needs to optimize the engine structure to reduce the total pressure loss.

关键词： Detonation Pressure gain characteristics Propulsive performance Supersonic internal compression inlet Valve/valveless Thermal cycle

A thermosensitive chitosan-based hydrogel for controlled release of insulin

在线全文

学校读者我要写书评

暂无评论

Frontiers of Materials Science 2014年第2期8卷 142-149页

作者： Ting-Ting GAO Ming KONG Xiao-Jie CHENG Gui-Xue XIA Yuan-Yuan GAO Xi-guang CHEN Dong Su cha HyunJin PARK ColLege of Marine Life Science Ocean University of China Qingdao 266003 China College of Life Sciences and Biotechnology Korea University Seoul 136-701 Korea

Present study aims at synthesizing a thermosensitive hydrogel for controlled release of insulin. According to a modified method, hydroxybutyl chitosan （HBC） hydrogel possessed thermal sensitivity is prepared which can form hydrogel at over 25℃. The HBC hydrogel is non-cytotoxic to mice fibroblasts cells （L929）. Insulin is 100% entrapped in the hydrogel, 38% of which is released in vitro from the concentration of 5% hydrogel after 48 h, whereas by enzymolysis with lysozyme, 80% of the total insulin is released after 48h. This study suggests that HBC hydrogel could be utilized for controlled release of insulin in a non-invasive manner.

关键词： hydroxybutyl chitosan hydrogel thermosensitive insulin controlledrelease

Conception and Design of Active Balancer for Planar Mechanisms

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 Mechanical Engineering 2009年第6期22卷 822-832页

作者： ZHANG Ying YAO Yan-An cha Jianzhong School of Mechanical and Electronic Control Engineering Beijing Jiaotong University Beijing 100044 China

The dynamic balancing is an important issue in mechanism design. For the existing balancing methods, both passive and active ones, there is still room for improvement in adaplability and independency. In view of this, a concept of active balancer is developed as a new solution for the dynamic balancing with more flexibility. The proposed balancer is an independent additional device with a control system inside, which consists of a two-degree-of-freedom （DOF） linkage and a controllable motor, and can be attached to a machine expediently with little change to its original structure and motion. One of the two inputs of the two-DOF linkage shares the same shaft with its output, which is connected to the input shaft of a machine to be balanced and driven by the original actuator. The other input is driven by the control motor. By properly selecting the speed trajectories of the control motor and link parameters of the two-DOF linkage, one or more dynamic effects of the mechanisms can be minimized or eliminated adaptively. The design procedure of the active balancer is put forward and a two-step optimization is developed to find out optimal design parameters of the balancer for various design requirements and constraints. Taking a force-balanced crank-rocker mechanism as the reference mechanism, numerical examples are given to illustrate the design procedure. The balancing effects of the proposed balancer are compared with those of the existing adding dyads （DYAD） method. The results show that the introduction of the control system provides the active balancer with better balancing effect and more flexibility than the DYAD method. A considerable reduction in the dynamic effects （input torque, shaking moment and shaking force） can be achieved for different balancing object by designing the structural and control parameters of the balancer, and the deterioration of dynamic performance caused by alterative working conditions can be compensated effectively by redesigning the

关键词： active balancing shaking moment input torque shaking force optimum balancing two-degree-of-freedom linkage