On the Loess Plateau, water is the main limiting factors for vegetation growth. Root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. Even-aged sta...On the Loess Plateau, water is the main limiting factors for vegetation growth. Root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. Even-aged stands ofRobinia pseudoacacia on slope lands facing south and north were selected as sampling plots for root distribution investigation. Investigatiing results showed that indicated that on all sites, root biomass decreased with depth, and the distribution depth of fine root was deeper than that of coarser root. The results of variance analysis indicated that there were great differences in root biomass among different diameter classes, and coarser root was the main sources of variance, and the root biomass, especially fine root (?<3mm) biomass on northern exposition sites was bigger than that on southern exposition sites. Analysis of the vertical root distribution parameters, root extinction coefficient, β indicated that the value of β on northern exposition was more than 0.982, while the value of β on southern exposition was less than 0.982, which indicated that the vertical root distribution depth ofRobinia pseudoacacia on southern exposition was deeper than that on southern exposition. And the distribution depth of fine roots (Φ<1mm) was deeper than that of thicker roots(Φ<3mm), which was in favor of the uptake of water and nutrients from deeper layers, helped the trees to adapt the arid environment, and promoted the growth of the upper parts of the tree. Keywords Root diameter classes - Variance analysis - Root extinction coefficient - Vertical distribution characters - Site conditions - Loess Plateau CLC number S792.27.01 Document code A Foundation Item: This research was supported by National Natural Science Foundation of China (30371150 and 40371075).Biography: LI Peng (1974-) male, post: Ph. D. in Northwest Scientific & Technological University of Agriculture and Forestry, Yangling 712100, Shaanxi Province, P. R. China. Tel: 029-82312651.Responsible editor: Chai Ruihal展开更多
In this paper, the fixed-point Theorem i s used to estimate an asymptotic solution of boundary value problems for a class o f third order quasilinear differential equation and the uniformly valid asymptot ic expansio...In this paper, the fixed-point Theorem i s used to estimate an asymptotic solution of boundary value problems for a class o f third order quasilinear differential equation and the uniformly valid asymptot ic expansion of solution of any orders including boundary layer is obtained.展开更多
In the past fifteen years, the attention of ship safety treatment as an objective rather than a constraint has started to sweep through the whole maritime industry. The risk-based ship design （RBD） methodology, advo...In the past fifteen years, the attention of ship safety treatment as an objective rather than a constraint has started to sweep through the whole maritime industry. The risk-based ship design （RBD） methodology, advocating systematic integration of risk assessment within the conventional design process has started to takeoff. Despite this wide recognition and increasing popularity, important factors that could potentially undermine the quality of the results come from both quantitative and qualitative aspects during the risk assessment process. This paper details a promising solution by developing a formalized methodology for risk assessment through effective storing and processing of historical data combined with data generated through first-principle approaches. This method should help to generate appropriate risk models in the selected platform （Bayesian networks） which can be employed for decision making at design stare.展开更多
A kind of nanokaolin powder with a thickness of 20-50nm and an average diameter of 300nm is produced through combined procedure of purification, delamination, surface modification and pulverization. The application ex...A kind of nanokaolin powder with a thickness of 20-50nm and an average diameter of 300nm is produced through combined procedure of purification, delamination, surface modification and pulverization. The application experiments in butadiene rubber (BR), ethylene-propylene diene methylene (EPDM), and natural rubber (NR) indicates that this nano-kaolin powder material is much better than precipitated silica in reinforcement, while in styrene-butadiene rubber (SBR) it is close to precipitated silica. Nanokaolin is of superiority in elasticity, elongation at break, anti-flexure property.展开更多
Shot cokes are frequently formed in the delayed coking unit treating the super viscous oil at PetroChina＇s Liaohe Petrochemical Company. Considerable work has been carded out to avoid the formation of shot cokes. The...Shot cokes are frequently formed in the delayed coking unit treating the super viscous oil at PetroChina＇s Liaohe Petrochemical Company. Considerable work has been carded out to avoid the formation of shot cokes. The test results obtained have shown that the property of super viscous oil has played a key role in the formation of shot cokes. After adjusting and optimizing the process indices the operating regime of the delayed coking unit at a throughput of 118t/h of the super viscous oil is specified as follows： a reaction temperature of 498-502℃, a reaction pressure of 0.17-0.25 MPa, a recycle ratio of 0.5-0.6 and a fractionation tower bottom temperature of 355-365 ℃. In the meantime, the delayed coking process has adopted measures to enhance pre-fractionation of the feedstock to rationally remove light fractions and maintain a steady gas velocity in order to avoid the formation of shot cokes.展开更多
The basic function of the Internet is to delivery data(what) to serve the needs of all applications. IP names the attachment points(where) to facilitate ubiquitous interconnectivity as the current way to deliver data....The basic function of the Internet is to delivery data(what) to serve the needs of all applications. IP names the attachment points(where) to facilitate ubiquitous interconnectivity as the current way to deliver data. The fundamental mismatch between data delivery and naming attachment points leads to a lot of challenges, e.g., mapping from data name to IP address, handling dynamics of underlying topology, scaling up the data distribution, and securing communication, etc. Informationcentric networking(ICN) is proposed to shift the focus of communication paradigm from where to what, by making the named data the first-class citizen in the network, The basic consensus of ICN is to name the data independent from its container(space dimension) and session(time dimension), which breaks the limitation of point-to-point IP semantic. It scales up data distribution by utilizing available resources, and facilitates communication to fit diverse connectivity and heterogeneous networks. However, there are only a few consensuses on the detailed design of ICN, and quite a few different ICN architectures are proposed. This paper reveals the rationales of ICN from the perspective of the Internet evolution, surveys different design choices, and discusses on two debatable topics in ICN, i.e.,self-certifying versus hierarchical names, and edge versus pervasive caching. We hope this survey helps clarify some mis-understandings on ICN and achieve more consensuses.展开更多
Objective To investigate the diagnosis and therapy of mediastinal enterogenous cysts in children. Methods Clinical data of 17 cases with mediastinal enterogenous cysts within 19 years in our hospital were retrospectiv...Objective To investigate the diagnosis and therapy of mediastinal enterogenous cysts in children. Methods Clinical data of 17 cases with mediastinal enterogenous cysts within 19 years in our hospital were retrospectively analyzed. Results One case was intramural esophageal cyst and 16 cases were enteric cysts, two among which were complicated with abdominal enteric duplications. Most cases presented with symptoms of respiratory distress. Twelve cases were complicated with vertebral anomalies. Ultrasound helpful in confirming the cystic nature of these lesions. posterior mediastinum. of 12 cases and magnetic resonance imaging of 4 cases were Eight cases had technetium-99m pertechnetate scintigraphy of posterior mediastinum.Conclusions Most patients present with symptoms of respiratory distress, complicated with vertebral anomalies. Ultrasonography and magnetic resonance imaging may be helpful in confirming the cystic nature of these lesions. Technetium-99m pertechnetate scintigraphy is the most effective method for differentiation of the disease from other mediastinal cysts.展开更多
Aim To investigate the existence of positive solutions for impulsive neutral differential equations. Methods The Banach contraction principle was used to establish our results. Results and Conclusion The results of...Aim To investigate the existence of positive solutions for impulsive neutral differential equations. Methods The Banach contraction principle was used to establish our results. Results and Conclusion The results of the existence of positive solutions for impulsive neutral differential equations are obtained.展开更多
The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscilla...The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscillation of neutral differential equation with positive and negative coefficients are obtained.展开更多
In this paper,the initial boundary value problems of the nonlinear Sobolev-Galpern equation are studied.The existence,uniqueness of local solution for the problem are obtained by means of a special Green's functio...In this paper,the initial boundary value problems of the nonlinear Sobolev-Galpern equation are studied.The existence,uniqueness of local solution for the problem are obtained by means of a special Green's function and the contraction mapping principle.Finally,the blow-up of solution in finite time under some assumed conditions is proved with the aid of Jensen's inequality.展开更多
Objective To establish a multiplex polymerase chain reaction （M-PCR） assay for simultaneous detection of pathogens causing genital ulcer disease （GUD）. Mothods Based on the gene-specific region of the following p...Objective To establish a multiplex polymerase chain reaction （M-PCR） assay for simultaneous detection of pathogens causing genital ulcer disease （GUD）. Mothods Based on the gene-specific region of the following pathogens： Chlamydia trachomatis omp l/ompb, herpes simplex virus （HSV） DNA polymerase, Treponema pollidum tpp47, Haemophilus ducreyi 16s rRNA, four sets of primers were designed and an M-PCR assay was developed to detect four pathogens in one test. The assay was evaluated with diagnostic result of golden standard for each pathogen.Results Of the 51 clinical samples, M-PCR showed slightly higher positive rate （47.1%） of HSV than cell culture （23.6%）. Meanwhile, the positive rate of T. pallidum detected by M-PCR and dark-field microscopy was 19.6% （10/51） and 15.7% （8/51）, respectively. Only one sample was positive for H. ducreyi and no sample was positive for C. trachomatis detected by both M-PCR assay and culture. Conclusion This primary study indicated that M-PCR assay can simultaneously and rapidly detect the four etiologic pathogens causing GUD.展开更多
Both right and left ventricles are developed from two adjacent segments of the primary heart tube. Though they are different with regard to shape and power, they mirror each other in terms of behavior. This is the fir...Both right and left ventricles are developed from two adjacent segments of the primary heart tube. Though they are different with regard to shape and power, they mirror each other in terms of behavior. This is the first level of symmetry in cardiac function assessment. Both cardiac muscle contraction and relaxation are active. This constructs the second level of symmetry in cardiac function assessment. Combination of the two levels will help to find some hidden indexes or approaches to evaluate cardiac function. In this article, four major indexes from echocardiography were analyzed under this principal, another seventeen indexes or measurement approaches came out of the shadow, which is very helpful in the assessment of cardiac function, especially for the right cardiac function and diastolic cardiac function.展开更多
This paper concentrates on the research of plaster-bonded moulding matertal with coal mine waste as its major filler and its process. Having made a careful investigation of various factorsaffecting properties of the m...This paper concentrates on the research of plaster-bonded moulding matertal with coal mine waste as its major filler and its process. Having made a careful investigation of various factorsaffecting properties of the moulding material, the authors optimize several new formulations of thismaterial and the prarees which are inexpensive, convenient in application, precise in bokling sizoof moulds.展开更多
The decay estimations of the solution to an elliptic equation with dynamical boundary condition is considered.We proved that,for suitable initial datum,the energy of the solution decays "in time" exponential...The decay estimations of the solution to an elliptic equation with dynamical boundary condition is considered.We proved that,for suitable initial datum,the energy of the solution decays "in time" exponentially if p=0,whereas the decay is polynomial order if p>0.展开更多
Due to the rapid development,Internet has become the main field for brand building.Under this circumstance,the image of the brand is always consistent with the consumers' perception.Therefore,this study uses the m...Due to the rapid development,Internet has become the main field for brand building.Under this circumstance,the image of the brand is always consistent with the consumers' perception.Therefore,this study uses the method of text mining of search engine to explore the categories of brand archetype based on Brand Personality Theory from the perspective of Internet.The results find that 12 brand archetypes,including caregiver,sage,hero,innocent,dominator,creator,vitality,explorer,stylish woman,lover,cooperator,and vogue gentleman,have a high degree explanation.Deeper study uses case study to verify the reasonability and effectiveness of the classification standard.展开更多
There are several important generalizations of martingales such as games fairer with time, quasi-mils and sequential martingales in the limit. In the note, we shall consider all possible structures of a probability sp...There are several important generalizations of martingales such as games fairer with time, quasi-mils and sequential martingales in the limit. In the note, we shall consider all possible structures of a probability space （Ω,A, （An）, P） associated with a stochastic basis（An） of sub a-fields of A with An ↑ A. Then, we shall apply them to establish some comparison results for the aforementioned generalizations of martingales.展开更多
Three different types of VGO were selected and cut into various distillates by true boiling-point distillation （TBD）, and the distillates were further separated into different components （saturates, aromatics and r...Three different types of VGO were selected and cut into various distillates by true boiling-point distillation （TBD）, and the distillates were further separated into different components （saturates, aromatics and resins） via solid phase extrac- tion （SPE）. The hydrocarbon components in saturates and aromatics were characterized on the quasi-molecular level by GC/ MS and CJC/TOF MS. Cracking reactions of VGO, their distillates, and hydrocarbon components （saturates and aromatics） were performed on an ACE （model AP） unit. Nine correlation parameters （mainly based on the previous assumption of basic structure Units, BSU） which could better reflect the structures and compositions of hydrocarbons were put forward based on the quasi-molecular level analysis data, and correlated with FCC product distribution by multi-regression method. A series of correlation formulas were obtained. The formulas were further verified by comparing experimental and calculated FCC yields emanated from two other VGO feedstocks.展开更多
Sandwich plate systems (SPS) are advanced materials that have begun to receive extensive attention in naval architecture and ocean engineering.At present, according to the rules of classification societies, a mixture ...Sandwich plate systems (SPS) are advanced materials that have begun to receive extensive attention in naval architecture and ocean engineering.At present, according to the rules of classification societies, a mixture of shell and solid elements are required to simulate an SPS.Based on the principle of stiffness decomposition, a new numerical simulation method for shell elements was proposed.In accordance with the principle of stiffness decomposition, the total stiffness can be decomposed into the bending stiffness and shear stiffness.Displacement and stress response related to bending stiffness was calculated with the laminated shell element.Displacement and stress response due to shear was calculated by use of a computational code write by FORTRAN language.Then the total displacement and stress response for the SPS was obtained by adding together these two parts of total displacement and stress.Finally, a rectangular SPS plate and a double-bottom structure were used for a simulation.The results show that the deflection simulated by the elements proposed in the paper is larger than the same simulated by solid elements and the analytical solution according to Hoff theory and approximate to the same simulated by the mixture of shell-solid elements, and the stress simulated by the elements proposed in the paper is approximate to the other simulating methods.So compared with calculations based on a mixture of shell and solid elements, the numerical simulation method given in the paper is more efficient and easier to do.展开更多
基金This research was supported by National Natural Science Foundation of China (30371150 and 40371075).
文摘On the Loess Plateau, water is the main limiting factors for vegetation growth. Root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. Even-aged stands ofRobinia pseudoacacia on slope lands facing south and north were selected as sampling plots for root distribution investigation. Investigatiing results showed that indicated that on all sites, root biomass decreased with depth, and the distribution depth of fine root was deeper than that of coarser root. The results of variance analysis indicated that there were great differences in root biomass among different diameter classes, and coarser root was the main sources of variance, and the root biomass, especially fine root (?<3mm) biomass on northern exposition sites was bigger than that on southern exposition sites. Analysis of the vertical root distribution parameters, root extinction coefficient, β indicated that the value of β on northern exposition was more than 0.982, while the value of β on southern exposition was less than 0.982, which indicated that the vertical root distribution depth ofRobinia pseudoacacia on southern exposition was deeper than that on southern exposition. And the distribution depth of fine roots (Φ<1mm) was deeper than that of thicker roots(Φ<3mm), which was in favor of the uptake of water and nutrients from deeper layers, helped the trees to adapt the arid environment, and promoted the growth of the upper parts of the tree. Keywords Root diameter classes - Variance analysis - Root extinction coefficient - Vertical distribution characters - Site conditions - Loess Plateau CLC number S792.27.01 Document code A Foundation Item: This research was supported by National Natural Science Foundation of China (30371150 and 40371075).Biography: LI Peng (1974-) male, post: Ph. D. in Northwest Scientific & Technological University of Agriculture and Forestry, Yangling 712100, Shaanxi Province, P. R. China. Tel: 029-82312651.Responsible editor: Chai Ruihal
文摘In this paper, the fixed-point Theorem i s used to estimate an asymptotic solution of boundary value problems for a class o f third order quasilinear differential equation and the uniformly valid asymptot ic expansion of solution of any orders including boundary layer is obtained.
基金the financial support received by the University of Strathclyde in the form of a postgraduate research scholarship for the duration of the second author’s P hD studies
文摘In the past fifteen years, the attention of ship safety treatment as an objective rather than a constraint has started to sweep through the whole maritime industry. The risk-based ship design （RBD） methodology, advocating systematic integration of risk assessment within the conventional design process has started to takeoff. Despite this wide recognition and increasing popularity, important factors that could potentially undermine the quality of the results come from both quantitative and qualitative aspects during the risk assessment process. This paper details a promising solution by developing a formalized methodology for risk assessment through effective storing and processing of historical data combined with data generated through first-principle approaches. This method should help to generate appropriate risk models in the selected platform （Bayesian networks） which can be employed for decision making at design stare.
基金Project supported by Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions, Ministry of Education, China
文摘A kind of nanokaolin powder with a thickness of 20-50nm and an average diameter of 300nm is produced through combined procedure of purification, delamination, surface modification and pulverization. The application experiments in butadiene rubber (BR), ethylene-propylene diene methylene (EPDM), and natural rubber (NR) indicates that this nano-kaolin powder material is much better than precipitated silica in reinforcement, while in styrene-butadiene rubber (SBR) it is close to precipitated silica. Nanokaolin is of superiority in elasticity, elongation at break, anti-flexure property.
文摘Shot cokes are frequently formed in the delayed coking unit treating the super viscous oil at PetroChina＇s Liaohe Petrochemical Company. Considerable work has been carded out to avoid the formation of shot cokes. The test results obtained have shown that the property of super viscous oil has played a key role in the formation of shot cokes. After adjusting and optimizing the process indices the operating regime of the delayed coking unit at a throughput of 118t/h of the super viscous oil is specified as follows： a reaction temperature of 498-502℃, a reaction pressure of 0.17-0.25 MPa, a recycle ratio of 0.5-0.6 and a fractionation tower bottom temperature of 355-365 ℃. In the meantime, the delayed coking process has adopted measures to enhance pre-fractionation of the feedstock to rationally remove light fractions and maintain a steady gas velocity in order to avoid the formation of shot cokes.
基金supported by the National High-tech R&D Program("863"Program)of China(No.2013AA013505)the National Science Foundation of China(No.61472213)State Scholarship Fund from China Scholarship Council(No.201406210270)
文摘The basic function of the Internet is to delivery data(what) to serve the needs of all applications. IP names the attachment points(where) to facilitate ubiquitous interconnectivity as the current way to deliver data. The fundamental mismatch between data delivery and naming attachment points leads to a lot of challenges, e.g., mapping from data name to IP address, handling dynamics of underlying topology, scaling up the data distribution, and securing communication, etc. Informationcentric networking(ICN) is proposed to shift the focus of communication paradigm from where to what, by making the named data the first-class citizen in the network, The basic consensus of ICN is to name the data independent from its container(space dimension) and session(time dimension), which breaks the limitation of point-to-point IP semantic. It scales up data distribution by utilizing available resources, and facilitates communication to fit diverse connectivity and heterogeneous networks. However, there are only a few consensuses on the detailed design of ICN, and quite a few different ICN architectures are proposed. This paper reveals the rationales of ICN from the perspective of the Internet evolution, surveys different design choices, and discusses on two debatable topics in ICN, i.e.,self-certifying versus hierarchical names, and edge versus pervasive caching. We hope this survey helps clarify some mis-understandings on ICN and achieve more consensuses.
文摘Objective To investigate the diagnosis and therapy of mediastinal enterogenous cysts in children. Methods Clinical data of 17 cases with mediastinal enterogenous cysts within 19 years in our hospital were retrospectively analyzed. Results One case was intramural esophageal cyst and 16 cases were enteric cysts, two among which were complicated with abdominal enteric duplications. Most cases presented with symptoms of respiratory distress. Twelve cases were complicated with vertebral anomalies. Ultrasound helpful in confirming the cystic nature of these lesions. posterior mediastinum. of 12 cases and magnetic resonance imaging of 4 cases were Eight cases had technetium-99m pertechnetate scintigraphy of posterior mediastinum.Conclusions Most patients present with symptoms of respiratory distress, complicated with vertebral anomalies. Ultrasonography and magnetic resonance imaging may be helpful in confirming the cystic nature of these lesions. Technetium-99m pertechnetate scintigraphy is the most effective method for differentiation of the disease from other mediastinal cysts.
文摘Aim To investigate the existence of positive solutions for impulsive neutral differential equations. Methods The Banach contraction principle was used to establish our results. Results and Conclusion The results of the existence of positive solutions for impulsive neutral differential equations are obtained.
文摘The oscillatory behavior of neutral differential equation with positive and negative coefficients is investigated by mathematics analysis technique and the fixed point principle. Some sufficient conditions for oscillation of neutral differential equation with positive and negative coefficients are obtained.
文摘In this paper,the initial boundary value problems of the nonlinear Sobolev-Galpern equation are studied.The existence,uniqueness of local solution for the problem are obtained by means of a special Green's function and the contraction mapping principle.Finally,the blow-up of solution in finite time under some assumed conditions is proved with the aid of Jensen's inequality.
文摘Objective To establish a multiplex polymerase chain reaction （M-PCR） assay for simultaneous detection of pathogens causing genital ulcer disease （GUD）. Mothods Based on the gene-specific region of the following pathogens： Chlamydia trachomatis omp l/ompb, herpes simplex virus （HSV） DNA polymerase, Treponema pollidum tpp47, Haemophilus ducreyi 16s rRNA, four sets of primers were designed and an M-PCR assay was developed to detect four pathogens in one test. The assay was evaluated with diagnostic result of golden standard for each pathogen.Results Of the 51 clinical samples, M-PCR showed slightly higher positive rate （47.1%） of HSV than cell culture （23.6%）. Meanwhile, the positive rate of T. pallidum detected by M-PCR and dark-field microscopy was 19.6% （10/51） and 15.7% （8/51）, respectively. Only one sample was positive for H. ducreyi and no sample was positive for C. trachomatis detected by both M-PCR assay and culture. Conclusion This primary study indicated that M-PCR assay can simultaneously and rapidly detect the four etiologic pathogens causing GUD.
文摘Both right and left ventricles are developed from two adjacent segments of the primary heart tube. Though they are different with regard to shape and power, they mirror each other in terms of behavior. This is the first level of symmetry in cardiac function assessment. Both cardiac muscle contraction and relaxation are active. This constructs the second level of symmetry in cardiac function assessment. Combination of the two levels will help to find some hidden indexes or approaches to evaluate cardiac function. In this article, four major indexes from echocardiography were analyzed under this principal, another seventeen indexes or measurement approaches came out of the shadow, which is very helpful in the assessment of cardiac function, especially for the right cardiac function and diastolic cardiac function.
文摘This paper concentrates on the research of plaster-bonded moulding matertal with coal mine waste as its major filler and its process. Having made a careful investigation of various factorsaffecting properties of the moulding material, the authors optimize several new formulations of thismaterial and the prarees which are inexpensive, convenient in application, precise in bokling sizoof moulds.
基金Supported by the National Natural Science Foundation of China(10671182)Supported by the Natural Science Foundation of Henan Province(0611053300+1 种基金200510463024)Supported by the Young Skeleton Teacher Project of the Higher School of Henan Province
文摘The decay estimations of the solution to an elliptic equation with dynamical boundary condition is considered.We proved that,for suitable initial datum,the energy of the solution decays "in time" exponentially if p=0,whereas the decay is polynomial order if p>0.
基金supported by Project 71202155 of National Science Funds for Distinguished Young Scientists of China
文摘Due to the rapid development,Internet has become the main field for brand building.Under this circumstance,the image of the brand is always consistent with the consumers' perception.Therefore,this study uses the method of text mining of search engine to explore the categories of brand archetype based on Brand Personality Theory from the perspective of Internet.The results find that 12 brand archetypes,including caregiver,sage,hero,innocent,dominator,creator,vitality,explorer,stylish woman,lover,cooperator,and vogue gentleman,have a high degree explanation.Deeper study uses case study to verify the reasonability and effectiveness of the classification standard.
基金Supported by the Natural Science Foundation of the Education Department of Henan province(200510483002)
文摘There are several important generalizations of martingales such as games fairer with time, quasi-mils and sequential martingales in the limit. In the note, we shall consider all possible structures of a probability space （Ω,A, （An）, P） associated with a stochastic basis（An） of sub a-fields of A with An ↑ A. Then, we shall apply them to establish some comparison results for the aforementioned generalizations of martingales.
文摘Three different types of VGO were selected and cut into various distillates by true boiling-point distillation （TBD）, and the distillates were further separated into different components （saturates, aromatics and resins） via solid phase extrac- tion （SPE）. The hydrocarbon components in saturates and aromatics were characterized on the quasi-molecular level by GC/ MS and CJC/TOF MS. Cracking reactions of VGO, their distillates, and hydrocarbon components （saturates and aromatics） were performed on an ACE （model AP） unit. Nine correlation parameters （mainly based on the previous assumption of basic structure Units, BSU） which could better reflect the structures and compositions of hydrocarbons were put forward based on the quasi-molecular level analysis data, and correlated with FCC product distribution by multi-regression method. A series of correlation formulas were obtained. The formulas were further verified by comparing experimental and calculated FCC yields emanated from two other VGO feedstocks.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No.HEUCFR 1003
文摘Sandwich plate systems (SPS) are advanced materials that have begun to receive extensive attention in naval architecture and ocean engineering.At present, according to the rules of classification societies, a mixture of shell and solid elements are required to simulate an SPS.Based on the principle of stiffness decomposition, a new numerical simulation method for shell elements was proposed.In accordance with the principle of stiffness decomposition, the total stiffness can be decomposed into the bending stiffness and shear stiffness.Displacement and stress response related to bending stiffness was calculated with the laminated shell element.Displacement and stress response due to shear was calculated by use of a computational code write by FORTRAN language.Then the total displacement and stress response for the SPS was obtained by adding together these two parts of total displacement and stress.Finally, a rectangular SPS plate and a double-bottom structure were used for a simulation.The results show that the deflection simulated by the elements proposed in the paper is larger than the same simulated by solid elements and the analytical solution according to Hoff theory and approximate to the same simulated by the mixture of shell-solid elements, and the stress simulated by the elements proposed in the paper is approximate to the other simulating methods.So compared with calculations based on a mixture of shell and solid elements, the numerical simulation method given in the paper is more efficient and easier to do.
