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减压渣油组分中芳环数分布的同步荧光光谱研究 被引量:12
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作者 王子军 梁文杰 +1 位作者 阙国和 钱家麟 《石油学报(石油加工)》 EI CAS CSCD 北大核心 1999年第4期67-71,共5页
减压渣油组分的同步荧光光谱能够较好地反映出各极性和芳香度不同的组分的芳香环系大小。平均来说,减压渣油的芳香分中的芳香结构以2~4环为主,胶质中的芳香结构以3~5环为主。
关键词 减压渣油 同步荧光光谱 环数分布 组织成分
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生物质燃料室内燃烧PM2.5中多环芳烃的排放特征 被引量:4
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作者 吴丞往 林澍 +3 位作者 孙军军 李沐霏 周欣 程晨 《湖北农业科学》 2019年第21期87-91,共5页
以浙江省典型农村地区3户家庭为试验地点,以不同类型生物质燃料为能源,研究不同类型炉灶、不同场所(厨房、卧室、客厅)空气PM2.5中15种多环芳烃(PAHs)的排放特征,同时采用毒性当量因子评估PAHs对人群健康的影响。结果表明,农户1、农户2... 以浙江省典型农村地区3户家庭为试验地点,以不同类型生物质燃料为能源,研究不同类型炉灶、不同场所(厨房、卧室、客厅)空气PM2.5中15种多环芳烃(PAHs)的排放特征,同时采用毒性当量因子评估PAHs对人群健康的影响。结果表明,农户1、农户2室内不同地点各燃料产生的PM2.5中PAHs大小为客厅>厨房>卧室,农户3燃烧生物质燃料竹子和菌菇时室内不同地点PM2.5中PAHs浓度为厨房>客厅>卧室,而燃烧木头时,农户3卧室中PM2.5中PAHs浓度略高于客厅。3家农户燃烧生物质燃料产生的PM2.5中PAHs浓度为农户2(204.11 ng/m^3)>农户3(141.65 ng/m^3)>农户1(128.14 ng/m^3)。PM2.5中各类PAHs厨房整体呈5~6环>3~4环>2环的变化趋势;客厅和卧室农户1和农户2整体呈2~3环>5~6环>4环的变化趋势,农户3整体呈5~6环>2~3环>4环的变化趋势。相比菌菇,竹子、木头燃烧过程中产生PAHs的较少。3家农户室内不同地点、不同燃料的致癌风险(ILCR)值大部分介于10-6~10-4,表明具有潜在的致癌风险。 展开更多
关键词 生物质燃料 PM2.5 芳烃(PAH) 环数分布 风险评估
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Density Matrix for Mesoscopic Distributed Parameter Circuits
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作者 JIYing-Hua WANGQi LUOHai-Mei LEIMin-Sheng 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第3期547-550,共4页
Under the Born-von-Karmann periodic boundary condition, we propose a quantization scheme for non-dissipative distributed parameter circuits (i.e. a uniform periodic transmission line). We find the unitary operator for... Under the Born-von-Karmann periodic boundary condition, we propose a quantization scheme for non-dissipative distributed parameter circuits (i.e. a uniform periodic transmission line). We find the unitary operator for diagonalizing the Hamiltonian of the uniform periodic transmission line. The unitary operator is expressed in a coordinate representation that brings convenience to deriving the density matrix rho(q,q',beta). The quantum fluctuations of charge and current at a definite temperature have been studied. It is shown that quantum fluctuations of distributed parameter circuits, which also have distributed properties, are related to both the circuit parameters and the positions and the mode of signals and temperature T. The higher the temperature is, the stronger quantum noise the circuit exhibits. 展开更多
关键词 mesoscopic distributed parameter circuits density matrix quantum fluctuations
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A Pole Assignment Design Method of Process Control System for Tubular Heat Exchanger
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作者 周清泉 《Chinese Quarterly Journal of Mathematics》 CSCD 1992年第4期13-19,共7页
This Paper has first studied the simplified model of tubular heat exchanger which is widely used in the industry and other field.On the basis of reference 2,a new pole assignment design method of pro-cess control syst... This Paper has first studied the simplified model of tubular heat exchanger which is widely used in the industry and other field.On the basis of reference 2,a new pole assignment design method of pro-cess control system with derivative control action is found.For the above system,the method and the for-mation which calculate the feedback matrix K and gain matrix L is given,and the simulation of the system is made. 展开更多
关键词 tubular heat exchanger process control system pole assignment design method feedback matrix Gain matrix
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Distribution of Elements in Primitive Sequences over Z_(p^e)
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作者 范淑琴 韩文报 《Journal of Mathematical Research and Exposition》 CSCD 北大核心 2004年第2期219-224,共6页
Using the estimates of character sums over Galoi8 rings and the trace de-scription of primitive sequences over Z_(p^e), we obtain an estimate for the frequency of theoccurrences of any element in Z_(p^e) in one period... Using the estimates of character sums over Galoi8 rings and the trace de-scription of primitive sequences over Z_(p^e), we obtain an estimate for the frequency of theoccurrences of any element in Z_(p^e) in one period of a primitive sequence, which is betterthan Kuzmin's results if n >4e, where n is the degree of the generating polynomial ofthe primitive sequence. 展开更多
关键词 primitive sequence over ring element distribution character sum
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PARTICULATE SUSPENSION FLOW INDUCED BY SINUSOIDAL PERISTALTIC WAVES THROUGH ECCENTRIC CYLINDERS: THREAD ANNULAR 被引量:4
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作者 KH. S. MEKHEIMER Y. ABD ELMABOUD A. I. ABDELLATEEF 《International Journal of Biomathematics》 2013年第4期113-137,共25页
This paper describes a new model for obtaining analytical solutions of peristaltic flow through eccentric annuli. A mathematical model of peristaltic pumping of a fluid mixture (as blood model) in a circular eccentr... This paper describes a new model for obtaining analytical solutions of peristaltic flow through eccentric annuli. A mathematical model of peristaltic pumping of a fluid mixture (as blood model) in a circular eccentric cylinders is presented and it is motivated due to the fact that thread injection is a promising method for placing medical implants within the human body with minimum surgical trauma. For the eccentric annuli, the inner cylinder is rigid and moving with a constant velocity V, and the outer one is hollow flexible cylinder that has a sinusoidal wave traveling down its wall. The coupled differential equations for both the fluid and the particle phases have been solved by using two methods and the expressions for the velocity distribution of fluid and particle phase, flow rate, pressure drop, friction forces at the inner and outer cylinders have been derived. The results obtained are discussed in brief. The significance of the particle concentration and the eccentricity parameter as well as the nature of the basic flow has been well explained. 展开更多
关键词 ECCENTRIC annulus flows particle fluid suspension PERISTALSIS ENDOSCOPE
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Modeling Long-term Forest Carbon Spatiotemporal Dynamics With Historical Climate and Recent Remote Sensing Data 被引量:1
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作者 Jing M.Chen 《Science Foundation in China》 CAS 2010年第1期30-56,共27页
Forests have long life cycles of up to several hundred years and longer.They also have very different growth rates at different stages of their life cycles.Therefore the carbon cycle in forest ecosystems has long time... Forests have long life cycles of up to several hundred years and longer.They also have very different growth rates at different stages of their life cycles.Therefore the carbon cycle in forest ecosystems has long time scales,making it necessary to consider forest age in estimating the spatiotemporal dynamics of carbon sinks in forests.The focus of this article is to review methods for combining recent remote sensing data with historical climate data for estimating the forest carbon source and sink distribution.Satellite remote sensing provides useful data for the land surface in recent decades. The information derived from remote sensing data can be used for short-term forest growth estimation and for mapping forest stand age for longterm simulations.For short-term forest growth estimation, remote sensing can provide forest structural parameters as inputs to process-based models,including big-leaf,two-leaf,and multi-layered models. These models use different strategies to upscale from leaf to canopy,and their reliability and suitability for remote sensing applications will be examined here.For long-term forest carbon cycle estimation, the spatial distribution of the forest growth rate(net primary productivity,NPP) modeled using remote sensing data in recent years is a critical input.This input can be combined with a forest age map to simulate the historical variation of NPP under the influence of climate and atmospheric changes. Another important component of the forest carbon cycle is heterotrophic respiration in the soil,which depends on the sizes of soil carbon pools as well as climate conditions.Methods for estimating the soil carbon spatial distribution and its separation into pools are described.The emphasis is placed on how to derive the soil carbon pools from NPP estimation in current years with consideration of forest carbon dynamics associated with stand age variation and climate and atmospheric changes.The role of disturbance in the forest carbon cycle and the effects of forest regrowth after disturbance are also considered in this review.An example of national forest carbon budget estimation in Canada is given at the end.It illustrates the importance of forest stand age structure in estimating the national forest carbon budgets and the effects of climate and atmospheric changes on the forest carbon cycle. 展开更多
关键词 forest carbon cycle forest age DISTURBANCE remote sensing NBP NPP NEP
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Exact transformation optics by using electrostatics
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作者 Pengfei Zhao Guoxiong Cai Huanyang Chen 《Science Bulletin》 SCIE EI CSCD 2022年第3期246-255,共10页
We present a novel method for designing transformation optical devices based on electrostatics.An arbi-trary transformation of electrostatic field can lead to a new refractive index distribution,where wave-fronts and ... We present a novel method for designing transformation optical devices based on electrostatics.An arbi-trary transformation of electrostatic field can lead to a new refractive index distribution,where wave-fronts and energy flux lines correspond to equipotential surfaces and electrostatic flux lines,respectively.Owing to scalar wave propagating exactly following an eikonal equation,wave optics and geometric optics share the same solutions in the devices.The method is utilized to design multipole lenses derived from multipoles in electrostatics.The source and drain in optics are considered as corre-sponding to positive charge and negative charge in the static field.By defining winding numbers in vir-tual and physical spaces,we explain the reason for some multipole lenses with illusion effects.Besides,we introduce an equipotential absorber to replace the drain to correspond to a negative charge with a grounded conductor.Therefore,it is a very general platform to design intriguing devices based on the combination of electrostatics and transformation optics. 展开更多
关键词 Transformation optics ELECTROSTATICS Multipole lenses Winding number
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The weight distributions of a class of non-primitive cyclic codes with two nonzeros
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作者 ZHENG DaBin ZHOU FengLi +1 位作者 HU Lei ZENG XiangYong 《Science China Mathematics》 SCIE CSCD 2015年第6期1285-1296,共12页
Recently, a class of non-primitive cyclic codes with two nonzeros have received much attention of researchers and their weight distributions have been obtained for several cases of two key parameters related to the no... Recently, a class of non-primitive cyclic codes with two nonzeros have received much attention of researchers and their weight distributions have been obtained for several cases of two key parameters related to the nonzeros. In this paper, by evaluating certain Jacobi sums, we determine the weight distributions of this class of cyclic codes for one more special case. 展开更多
关键词 primitive codes Jacobi multiplicative evaluating integer multiplicity exponential simplify details
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