The reduced weight and improved efficiency of modern aeronautical structures result in a decreasing separation of frequency ranges of rigid and elastic modes.Particularly,a high-aspect-ratio flexible flying wing is pr...The reduced weight and improved efficiency of modern aeronautical structures result in a decreasing separation of frequency ranges of rigid and elastic modes.Particularly,a high-aspect-ratio flexible flying wing is prone to body freedomflutter(BFF),which is a result of coupling of the rigid body short-periodmodewith 1st wing bendingmode.Accurate prediction of the BFF characteristics is helpful to reflect the attitude changes of the vehicle intuitively and design the active flutter suppression control law.Instead of using the rigid body mode,this work simulates the rigid bodymotion of the model by using the six-degree-of-freedom(6DOF)equation.A dynamicmesh generation strategy particularly suitable for BFF simulation of free flying aircraft is developed.An accurate Computational Fluid Dynamics/Computational Structural Dynamics/six-degree-of-freedom equation(CFD/CSD/6DOF)-based BFF prediction method is proposed.Firstly,the time-domain CFD/CSD method is used to calculate the static equilibrium state of the model.Based on this state,the CFD/CSD/6DOF equation is solved in time domain to evaluate the structural response of themodel.Then combinedwith the variable stiffnessmethod,the critical flutter point of the model is obtained.This method is applied to the BFF calculation of a flyingwing model.The calculation results of the BFF characteristics of the model agree well with those fromthe modalmethod andNastran software.Finally,the method is used to analyze the influence factors of BFF.The analysis results show that the flutter speed can be improved by either releasing plunge constraint or moving the center ofmass forward or increasing the pitch inertia.展开更多
In situ, compatibilization of low density polyethylene (LDPE) (30%) and nylon-6 (70%) blends through one-step reactive extrusion using t-BuOOH as an initiator and low molecular weight interfacial agents as compatibili...In situ, compatibilization of low density polyethylene (LDPE) (30%) and nylon-6 (70%) blends through one-step reactive extrusion using t-BuOOH as an initiator and low molecular weight interfacial agents as compatibilizers was studied. The compatibilizer contained a long chain hydrocarbon, double bond and two polar functional groups which was capable of reacting with both LDPE and nylon-6 in the presence of initiator to form a copolymer at the interface of the two polymer phases. The extruded blends exhibited significant enhancement in their compatibility based on morphological, thermal analysis and mechanical studies. The effect of the hydrocarbon chain length and structure of the functional group of the compatibilizer was also examined. It was found that blends prepared by using the compatibilizer containing longer hydrocarbon chain and amide group had better mechanical properties.展开更多
A combined system consisting of hydrolysis acidification, denitrification and nitrification reactors was used to remove carbon and nitrogen from the nylon - 6 production wastewater, which was characterized by good bio...A combined system consisting of hydrolysis acidification, denitrification and nitrification reactors was used to remove carbon and nitrogen from the nylon - 6 production wastewater, which was characterized by good biodegradability and high nitrogen concentration. The influences of Chemical Oxygen Demand （COD） in the influent, recirculation ratio, Hydraulic Residence Time （HRT） and Dissolved Oxygen （DO） concentration on the system performances were investigated. From results it could be seen that good performances have been achieved during the overall experiments periods, and COD, Total Nitrogen （TN）, NH^＋ -N and Suspended Solids （SS） in the effluent were 53, 16, 2 and 24 mg· L^-1, respectively, which has satisfied the first standard of wastewater discharge established by Environmental Protection Agency （EPA） of China. Furthermore, results showed that operation factors, viz. COD in the influent, recirculation ratio, HRT and DO concentration, all had important influences on the system performances.展开更多
为解决6LoWPAN(IPv6over Low power WPAN)设备与IPv6网络通信时的地址压缩问题,研究了6LoWPAN报头压缩方案,提出了一种基于短地址映射的改进压缩方案。6LoWPAN设备短地址由自身生成,IPv6网络节点短地址可由数据报中直接获取,避免了短地...为解决6LoWPAN(IPv6over Low power WPAN)设备与IPv6网络通信时的地址压缩问题,研究了6LoWPAN报头压缩方案,提出了一种基于短地址映射的改进压缩方案。6LoWPAN设备短地址由自身生成,IPv6网络节点短地址可由数据报中直接获取,避免了短地址注册、分配机制及地址冲突检测方法带来的开销,保证了短地址的唯一性。介绍了地址映射方法及地址映射表,详细阐述了设备处理流程及设计的路由地址通告和地址映射更新报文。性能分析表明,在传输负载较大,通信次数频繁的网络状况中,改进方案能有效减少报头开销,数据传输效率较6LoWPAN原方案有显著提高。展开更多
The mechanical properties and dynamic mechanical properties of blends composed of Nylon 6 and poly （ butylenes terephthalate） （PBT）, with styrene/maleic anhydride（SMA） as compatibilizer, were studied. The observ...The mechanical properties and dynamic mechanical properties of blends composed of Nylon 6 and poly （ butylenes terephthalate） （PBT）, with styrene/maleic anhydride（SMA） as compatibilizer, were studied. The observation on the morphologies of the etched surfaces of the cryogenically fractured specimens via scanning electron microscopy（SEM） demonstrated that in the compatibilized Nylon 6/PBT blends, there exists a finer and more uniform dispersion induced by the in-situ interfacial chemical reactions during the preparation than that in the corresponding uncompatibilized blends. On the other hand, the overall mechanical properties of the compatibilized blends could be remarkably im- proved compared with those of the uncompatibilized ones. Moreover, increasing the amount of the compatibilizer SMA leads to a more efficient dispersion of the PBT phase in Nylon 6/PBT blends. Furthermore, there exists an optimum level of SMA added to achieve the maximum mechanical properties. As far as the mechanism of this reactive compatibilization is concerned, the enhanced interfacial adhesion is necessary to obtain improved dispersion, stable phase morphology, and better mechanical properties.展开更多
1.The enzymes with relation to metabolism in the retinae of rabbits after acute ocluar hypertension were investigated by means of quantitative histochemistry and electron microscopic histocytochemistry.用光镜酶组织细...1.The enzymes with relation to metabolism in the retinae of rabbits after acute ocluar hypertension were investigated by means of quantitative histochemistry and electron microscopic histocytochemistry.用光镜酶组织细胞化学和电镜细胞化学方法,对家兔急性高眼压后视网膜内与糖代谢及分解代谢有关的葡萄糖-6-磷酸酶（G-6-Pase）、展开更多
基金This work was supported by the National Natural Science Foundation of China(No.11872212)and a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘The reduced weight and improved efficiency of modern aeronautical structures result in a decreasing separation of frequency ranges of rigid and elastic modes.Particularly,a high-aspect-ratio flexible flying wing is prone to body freedomflutter(BFF),which is a result of coupling of the rigid body short-periodmodewith 1st wing bendingmode.Accurate prediction of the BFF characteristics is helpful to reflect the attitude changes of the vehicle intuitively and design the active flutter suppression control law.Instead of using the rigid body mode,this work simulates the rigid bodymotion of the model by using the six-degree-of-freedom(6DOF)equation.A dynamicmesh generation strategy particularly suitable for BFF simulation of free flying aircraft is developed.An accurate Computational Fluid Dynamics/Computational Structural Dynamics/six-degree-of-freedom equation(CFD/CSD/6DOF)-based BFF prediction method is proposed.Firstly,the time-domain CFD/CSD method is used to calculate the static equilibrium state of the model.Based on this state,the CFD/CSD/6DOF equation is solved in time domain to evaluate the structural response of themodel.Then combinedwith the variable stiffnessmethod,the critical flutter point of the model is obtained.This method is applied to the BFF calculation of a flyingwing model.The calculation results of the BFF characteristics of the model agree well with those fromthe modalmethod andNastran software.Finally,the method is used to analyze the influence factors of BFF.The analysis results show that the flutter speed can be improved by either releasing plunge constraint or moving the center ofmass forward or increasing the pitch inertia.
文摘In situ, compatibilization of low density polyethylene (LDPE) (30%) and nylon-6 (70%) blends through one-step reactive extrusion using t-BuOOH as an initiator and low molecular weight interfacial agents as compatibilizers was studied. The compatibilizer contained a long chain hydrocarbon, double bond and two polar functional groups which was capable of reacting with both LDPE and nylon-6 in the presence of initiator to form a copolymer at the interface of the two polymer phases. The extruded blends exhibited significant enhancement in their compatibility based on morphological, thermal analysis and mechanical studies. The effect of the hydrocarbon chain length and structure of the functional group of the compatibilizer was also examined. It was found that blends prepared by using the compatibilizer containing longer hydrocarbon chain and amide group had better mechanical properties.
基金Shanghai Science and Technology Committee(No.042312045)Shanghai Post-doctor Fund
文摘A combined system consisting of hydrolysis acidification, denitrification and nitrification reactors was used to remove carbon and nitrogen from the nylon - 6 production wastewater, which was characterized by good biodegradability and high nitrogen concentration. The influences of Chemical Oxygen Demand （COD） in the influent, recirculation ratio, Hydraulic Residence Time （HRT） and Dissolved Oxygen （DO） concentration on the system performances were investigated. From results it could be seen that good performances have been achieved during the overall experiments periods, and COD, Total Nitrogen （TN）, NH^＋ -N and Suspended Solids （SS） in the effluent were 53, 16, 2 and 24 mg· L^-1, respectively, which has satisfied the first standard of wastewater discharge established by Environmental Protection Agency （EPA） of China. Furthermore, results showed that operation factors, viz. COD in the influent, recirculation ratio, HRT and DO concentration, all had important influences on the system performances.
文摘为解决6LoWPAN(IPv6over Low power WPAN)设备与IPv6网络通信时的地址压缩问题,研究了6LoWPAN报头压缩方案,提出了一种基于短地址映射的改进压缩方案。6LoWPAN设备短地址由自身生成,IPv6网络节点短地址可由数据报中直接获取,避免了短地址注册、分配机制及地址冲突检测方法带来的开销,保证了短地址的唯一性。介绍了地址映射方法及地址映射表,详细阐述了设备处理流程及设计的路由地址通告和地址映射更新报文。性能分析表明,在传输负载较大,通信次数频繁的网络状况中,改进方案能有效减少报头开销,数据传输效率较6LoWPAN原方案有显著提高。
基金Supported by the Natural Science Funds of Guizhou Province,China(No.GY-2005-3036)the National Basic Research Pro-gram of China(No.2005CB623802).
文摘The mechanical properties and dynamic mechanical properties of blends composed of Nylon 6 and poly （ butylenes terephthalate） （PBT）, with styrene/maleic anhydride（SMA） as compatibilizer, were studied. The observation on the morphologies of the etched surfaces of the cryogenically fractured specimens via scanning electron microscopy（SEM） demonstrated that in the compatibilized Nylon 6/PBT blends, there exists a finer and more uniform dispersion induced by the in-situ interfacial chemical reactions during the preparation than that in the corresponding uncompatibilized blends. On the other hand, the overall mechanical properties of the compatibilized blends could be remarkably im- proved compared with those of the uncompatibilized ones. Moreover, increasing the amount of the compatibilizer SMA leads to a more efficient dispersion of the PBT phase in Nylon 6/PBT blends. Furthermore, there exists an optimum level of SMA added to achieve the maximum mechanical properties. As far as the mechanism of this reactive compatibilization is concerned, the enhanced interfacial adhesion is necessary to obtain improved dispersion, stable phase morphology, and better mechanical properties.
文摘1.The enzymes with relation to metabolism in the retinae of rabbits after acute ocluar hypertension were investigated by means of quantitative histochemistry and electron microscopic histocytochemistry.用光镜酶组织细胞化学和电镜细胞化学方法,对家兔急性高眼压后视网膜内与糖代谢及分解代谢有关的葡萄糖-6-磷酸酶（G-6-Pase）、
