This paper analyzes the main elements in NS network simulator, makes adetailed view of dataflow management in a link, a node, and an agent, respectively, and introducesthe information described by its trace file. Base...This paper analyzes the main elements in NS network simulator, makes adetailed view of dataflow management in a link, a node, and an agent, respectively, and introducesthe information described by its trace file. Based on the analysis of transportation and treatmentof different packets in NS, a dataflow state machine is proposed with its states exchange triggeringevents and a dataflow analyzer is designed and implemented according to it. As the machine statefunctions, the analyzer can make statistic of total transportation flux of a specified dataflow andoffer a general fluctuation diagram. Finally, a concrete example is used to test its performance.展开更多
This paper gave an overview introduction about umbrella partnership real estate investment trust (UPREIT) to the readers who are not related to real estate and accounting major. To show how UPREIT defer capital gain t...This paper gave an overview introduction about umbrella partnership real estate investment trust (UPREIT) to the readers who are not related to real estate and accounting major. To show how UPREIT defer capital gain taxes,makes good cash flow and maximize profit in real estate finance,the paper included the theory and structure of UPREIT(real estate investment trust),partnership issues,advantage and disadvantage,and created a proforma to demonstrate how UPREIT works.展开更多
A large number of debris flows occurred simultaneously at around 8:30 to 8:50 a.m.on July 27,2011,at the center of Seoul,Korea.This area is located in the southern part of Seoul and is a densely populated district.As ...A large number of debris flows occurred simultaneously at around 8:30 to 8:50 a.m.on July 27,2011,at the center of Seoul,Korea.This area is located in the southern part of Seoul and is a densely populated district.As a result of the debris flow event,16 people were killed,30 houses were buried,and 116 houses were damaged around Umyeon Mountain,a relatively small mountain with a height of 312.6 m.Since the debris flow event,field investigations on the initiation and transportation zones of debris flows have been carried out.Rainfall data were collected from the automatic weather stations(AWSs) which are operated by the Korea Meteorological Administration(KMA).Video files recorded by residents were also acquired and used to analyze the flow characteristics of the debris flow.Field investigation shows that about 40 debris flows occurred around Umyeon Mountain and most of the debris flows were initiated by small slope failures.The effects of the precipitation that triggered the debris flows were analyzed as well.A landslide hazard map which considers slope gradient and aspect,strength of soil,hazard record,rainfall conditions,and vegetation,was constructed and compared with the initiation zones of debris flows.展开更多
A design method was developed to specify the profile of the continuously variable Mach-number nozzle for the supersonic wind tunnel. The controllable contour design technique was applied to obtaining the original nozz...A design method was developed to specify the profile of the continuously variable Mach-number nozzle for the supersonic wind tunnel. The controllable contour design technique was applied to obtaining the original nozzle profile, while other Machnumbers were derived from the transformation of the original profile. A design scheme, covering a Mach-number range of3.0<Ma<4.0, was shown to illustrate the present design technique. To fully validate the present design method, computational fluid dynamics(CFD) analyses were carried out to study the flow quality in the test area of the nozzle. The computed results indicate that exit uniform flow is obtained with 1.19% of the maximal Mach-number deviation at the nozzle exit. The present design method achieves the continuously variable Mach-number flow during a wind tunnel running.展开更多
Peace is a key concept in the Jewish tradition; it has a long history. It is also an extremely broad concept. The present article takes on the subject of contemporary peace between Israel and her neighbors, addressing...Peace is a key concept in the Jewish tradition; it has a long history. It is also an extremely broad concept. The present article takes on the subject of contemporary peace between Israel and her neighbors, addressing the issue from the vantage point of Judaism. While opinions on many issues are divided in Judaism today, all streams within the Jewish tradition uphold the concept of peace. Even so, each stream supports a somewhat different version of this ideal, subject to different limitations or reservations. One of the most serious challenges which Judaism today faces in connection with the State of Israel is the issue of exchanging territories for peace. The goal of the present paper is to show that while most approaches rooted in traditional Judaism have opposed such an exchange, Israel's religious political parties have endorsed it, advancing different arguments in support of their view. The method followed in the present paper is to study the arguments which have been used in support of peace agreements based on return or exchange of land. In light of the arguments put forth in the paper, to be counted among the accomplishments is a greater degree of openness--even on the part of the religious sector in Israel--toward the effort to achieve peace between Israel and her neighbors.展开更多
Social media like Twitter who serves as a novel news medium and has become increasingly popular since its establishment. Large scale first-hand user-generated tweets motivate automatic event detection on Twitter. Prev...Social media like Twitter who serves as a novel news medium and has become increasingly popular since its establishment. Large scale first-hand user-generated tweets motivate automatic event detection on Twitter. Previous unsupervised approaches detected events by clustering words. These methods detect events using burstiness,which measures surging frequencies of words at certain time windows. However,event clusters represented by a set of individual words are difficult to understand. This issue is addressed by building a document-level event detection model that directly calculates the burstiness of tweets,leveraging distributed word representations for modeling semantic information,thereby avoiding sparsity. Results show that the document-level model not only offers event summaries that are directly human-readable,but also gives significantly improved accuracies compared to previous methods on unsupervised tweet event detection,which are based on words/segments.展开更多
This research serves the primary purpose to support the reform of administration budgets for Taiwan Residents universities to optimize their document processing system. The main research method applied is quantitative...This research serves the primary purpose to support the reform of administration budgets for Taiwan Residents universities to optimize their document processing system. The main research method applied is quantitative analysis to explore the relationships between document quantity and each administration spending. The research observes that Taiwan Residents universities in general rely more on electronic systems to manage documents. Therefore, as proven by correlation test and regression model, personnel spending and miscellaneous spending are the only two categories which can help predict document flows. However, only miscellaneous spending is positively related to document quantity, so this category should be allocated with more funding. Personnel spending, on the contrary, should be less. For the long-term budgeting strategy, Taiwan Residents universities should begin with discovering problems from the existing system, design an allocation plan, execute the plan, and finally evaluate the outcomes. This project is on the first to explore the new academic research field which relates to logistics, budgeting, and university administration.展开更多
The peer-to-peer(P2P) file-sharing network as a vehicle of disseminating files has become very popular. The appearance of dozens of kinds of passive worms on this network has, however, made it unsecured. This proble...The peer-to-peer(P2P) file-sharing network as a vehicle of disseminating files has become very popular. The appearance of dozens of kinds of passive worms on this network has, however, made it unsecured. This problem has been paid attention and a few of models for passive worm propagation has been presented. Unfortunately, the dynamic properties of this network are ignored in these models. Given the fact, the characteristics of both this network and the passive worm are identified, and on this basis a new mathematical model of passive worm propagation on the P2P network is presented in applying epidemiology in this paper. Note that the dynamic properties of this network are considered in the presented model. The model has been validated by large scale simulation experiments, which demonstrates that the presented model may be used for analyzing the behaviors of passive worms and predicting the trend of their propagation.展开更多
In physics,the Klein-Gordon equation describes the motion of a quantum scalar or pseudoscalar field.Itis important to find actual values of its solutions in general timespace manifold.The paper deals with description ...In physics,the Klein-Gordon equation describes the motion of a quantum scalar or pseudoscalar field.Itis important to find actual values of its solutions in general timespace manifold.The paper deals with description ofdiscrete exterior calculus method for solving this equation numerically on space manifold and the time.The analysis ofstable condition and error for this method is also accomplished.展开更多
Hydrological processes in river basins of similar size and morphology may differ significantly due to different climatic conditions. This paper presents a comparative analysis of hydrological characteristics of two ri...Hydrological processes in river basins of similar size and morphology may differ significantly due to different climatic conditions. This paper presents a comparative analysis of hydrological characteristics of two river basins located in different climatic zones: the Wisok River Basin in the south-eastern Poland and the Chaohe River Basin in the northern China. The criteria of their choice were similarities in the basin area, main river length and topography. The results show that climate plays a key role in shaping fluvial conditions within the two basins. It is concluded that: 1) precipitation in the Wisok River Basin is more evenly distributed in the yearly cycle, while in the Chaohe River Basin it is highly concentrated in the few summer months; 2) spring snowmelt significantly contributes to runoff in the Wisok River Basin, while its role in the Chaohe River Basin is negligible; 3) in the Wisok River Basin, besides the peak flow in spring, there is also a period of high water in summer resulting from precipitation, while in the Chaohe River Basin there is only one high water period in summer; 4) the Wisok River Basin shows relatively higher stability in terms of the magnitude of intra- and inter-seasonal discharges; 5) during the multi-year observation period, a decrease in both precipitation and runoff was recorded in the two river basins.展开更多
Hybrid organic-inorganic polymer nanocomposites incorporating organically modified montmorillonite (MMT) and ultra-high molecular weight polyethylene (UHMWPE) were examined. UHMWPE/MMT hybrid nanocomposites were prepa...Hybrid organic-inorganic polymer nanocomposites incorporating organically modified montmorillonite (MMT) and ultra-high molecular weight polyethylene (UHMWPE) were examined. UHMWPE/MMT hybrid nanocomposites were prepared using gel and pressure-induced flow(PIF) processing methods at a gel weight concentration of 8% UHMWPE with various organoclay contents (0, 0.4, 0.8, 1.2, and 1.6 parts per hundred parts). The interlayer properties of the nanocomposites were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The thermal and mechanical interfacial properties of the nanocomposites were investigated through thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and the use of a universal test machine (UTM). TEM indicates that the nanocomposites are formed upon dispersion of MMT in the polymer matrix. From the DSC, TGA, and DMA results, we find that the thermal stability of the UHMWPE nanocomposites increases as the MMT content increases. The nanocomposites show higher tensile strengths than pure UHMWPE gel sheet. These findings indicate that the interfacial and mechanical properties are improved by the addition of MMT and PIF processing.展开更多
In this study, the authors experimentally investigated the changes of the mean velocity component profiles, half-widths (b12), turbulence intensities, Reynolds shear stress and intermittency of turbulence of a trans...In this study, the authors experimentally investigated the changes of the mean velocity component profiles, half-widths (b12), turbulence intensities, Reynolds shear stress and intermittency of turbulence of a transient plane turbulent jet developing from a jet exit into a hood opening. The values of maximum mean-velocity and half-widths of the axial velocity profile along the center-line of the jet are greater than those for a fully developed two-dimensional jet. Turbulence intensity in the axial direction is not affected by the flow rate ratio. At the same time, turbulence intensity in the lateral direction becomes greater as the hood is approached and the flow rate ratio Q3/Q1 becomes larger (QI is jet flow rate from nozzle and Q3 is suction flow rate produced by the hood). These experimental results are in accord with the distributions of production terms in the axial and lateral directions. Reynolds shear stress becomes smaller as the flow rate ratio becomes larger near the hood. Dimensionless distance y1/br2, from the center axis of the flow to the point where intermittency factor y becomes a constant value, narrows as the flow rate ratio becomes larger near the hood.展开更多
The influences due to several AVIs (airfoil-vortex interactions) are studied by using a two-dimensional CFD (computational fluid dynamics) method. The primary goal of this effort is to assess the variation of vort...The influences due to several AVIs (airfoil-vortex interactions) are studied by using a two-dimensional CFD (computational fluid dynamics) method. The primary goal of this effort is to assess the variation of vortex center location and vortex circulation associated with sequential AVI toward an improvement of the hybrid method of CFD and prescribed wake model, which closely relates to predicting the BVI (blade-vortex interaction) noise radiated from a helicopter rotor. The representative of sequential AVI is performed by single vortex and two airfoils. Investigations with respect to vortex center location and vortex circulation after AVIs have been made by varying the miss-distance, which is the vertical distance between the airfoil leading edge and the vortex center. Correlations between miss-distance and vorticity field show that there exists complicated vortex wake flow with several vortices newly induced in 1st AVI. The pressure fluctuation amplitude clarifies that the intensity in 2nd AV1 is significantly low compared to the intensity in 1st AVI due to the influence of vortex dissipation. Simulations turned out to modify the vortex center location represented by the hybrid method using an offset value for a streamwise direction and to dissipate the vortex circulation for improving the accuracy of BVI noise prediction.展开更多
This paper provides an overview of the state of art of reverse logistics and current status of waste management problems with special emphasis on developing countries. Logistics activities have been practiced and play...This paper provides an overview of the state of art of reverse logistics and current status of waste management problems with special emphasis on developing countries. Logistics activities have been practiced and played a fundamental role in the global economic development for over 5,000 years. It has then been transformed into different logistics branches and elaborates the emergency of reverse logistics as one of the most important. The paper presents the evolution of logistics into reverse logistics and how it relates to waste management both in the developed and developing world. Reverse logistics is a relatively new phenomenon in the research area which is mainly referring to damaged goods, the take back of products that should be returned to the manufacturers or distributors. Reverse logistics is relatively more practiced in an organized way in the developed world than in the developing countries in that the latter provided less value additions on reversed products.展开更多
Based on high-resolution,Array for Real-time Geostrophic Oceanography(Argo)profiles and Sea Level Anomaly(SLA)data,this study statistically analyzes and compares turbulent diapycnal mixing profiles inside and outside ...Based on high-resolution,Array for Real-time Geostrophic Oceanography(Argo)profiles and Sea Level Anomaly(SLA)data,this study statistically analyzes and compares turbulent diapycnal mixing profiles inside and outside mesoscale eddies in the Gulf Stream region.The result indicates that average diapycnal diffusivity at 300–540 m depths in anticyclonic eddies reaches4.0×10-5 m2 s-1.This is significantly higher than the 1.6×10-5 m2 s-1 outside eddies and 0.8×10-5 m2 s-1 in cyclonic eddies.Probabilities of diapycnal diffusivity greater than 10-4 m2 s-1 within anticyclonic and cyclonic eddies and outside eddies are29%,5%and 12%,respectively.However,magnitudes of average diapycnal diffusivity at 540–900 m depths in these three cases are of the same order,10-5 m2 s-1.Twenty-four of a total 38 anticyclonic eddies had enhanced mixing in the ocean interior,and 22 were observed during or shortly after strong winds.The coincidence between enhanced mixing and strong wind stress indicates that more wind-induced,near-inertial wave energy propagates downward in anticyclonic eddies.The deeper part of 12 profiles(below 540 m)in anticyclonic eddies had vertical overturns with Thorpe scale exceeding 5 m,among which three profiles had overturns reaching 20 m.Enhanced mixing may have occurred in deep layers of some profiles,although it was not evident in average conditions.展开更多
The contribution deals with the experimental and numerical investigation of compressible flow through the tip-section turbine blade cascade with the blade 54″ long. Experimental investigations by means of optical(int...The contribution deals with the experimental and numerical investigation of compressible flow through the tip-section turbine blade cascade with the blade 54″ long. Experimental investigations by means of optical(interferometry and schlieren method) and pneumatic measurements provide more information about the behaviour and nature of basic phenomena occurring in the profile cascade flow field. The numerical simulation was carried out by means of the EARSM turbulence model according to Hellsten [5] completed by the bypass transition model with the algebraic equation for the intermittency coefficient proposed by Straka and P?íhoda [6] and implemented into the in-house numerical code. The investigation was focused particularly on the effect of shock waves on the shear layer development including the laminar/turbulent transition. Interactions of shock waves with shear layers on both sides of the blade result usually in the transition in attached and/ or separated flow and so to the considerable impact to the flow structure and energy losses in the blade cascade.展开更多
基金The Natural Science Foundation of Jiangsu Province (BK2001205).
文摘This paper analyzes the main elements in NS network simulator, makes adetailed view of dataflow management in a link, a node, and an agent, respectively, and introducesthe information described by its trace file. Based on the analysis of transportation and treatmentof different packets in NS, a dataflow state machine is proposed with its states exchange triggeringevents and a dataflow analyzer is designed and implemented according to it. As the machine statefunctions, the analyzer can make statistic of total transportation flux of a specified dataflow andoffer a general fluctuation diagram. Finally, a concrete example is used to test its performance.
文摘This paper gave an overview introduction about umbrella partnership real estate investment trust (UPREIT) to the readers who are not related to real estate and accounting major. To show how UPREIT defer capital gain taxes,makes good cash flow and maximize profit in real estate finance,the paper included the theory and structure of UPREIT(real estate investment trust),partnership issues,advantage and disadvantage,and created a proforma to demonstrate how UPREIT works.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education,Science and Technology (2012014940)supported by a grant(Code#’08 RTIP B01-01) from the Regional Technology Innovation Program (RTIP)funded by the Ministry of Land Transport and Maritime Affairs of the Korean government
文摘A large number of debris flows occurred simultaneously at around 8:30 to 8:50 a.m.on July 27,2011,at the center of Seoul,Korea.This area is located in the southern part of Seoul and is a densely populated district.As a result of the debris flow event,16 people were killed,30 houses were buried,and 116 houses were damaged around Umyeon Mountain,a relatively small mountain with a height of 312.6 m.Since the debris flow event,field investigations on the initiation and transportation zones of debris flows have been carried out.Rainfall data were collected from the automatic weather stations(AWSs) which are operated by the Korea Meteorological Administration(KMA).Video files recorded by residents were also acquired and used to analyze the flow characteristics of the debris flow.Field investigation shows that about 40 debris flows occurred around Umyeon Mountain and most of the debris flows were initiated by small slope failures.The effects of the precipitation that triggered the debris flows were analyzed as well.A landslide hazard map which considers slope gradient and aspect,strength of soil,hazard record,rainfall conditions,and vegetation,was constructed and compared with the initiation zones of debris flows.
基金Project(11072264)supported by the National Natural Science Foundation of China
文摘A design method was developed to specify the profile of the continuously variable Mach-number nozzle for the supersonic wind tunnel. The controllable contour design technique was applied to obtaining the original nozzle profile, while other Machnumbers were derived from the transformation of the original profile. A design scheme, covering a Mach-number range of3.0<Ma<4.0, was shown to illustrate the present design technique. To fully validate the present design method, computational fluid dynamics(CFD) analyses were carried out to study the flow quality in the test area of the nozzle. The computed results indicate that exit uniform flow is obtained with 1.19% of the maximal Mach-number deviation at the nozzle exit. The present design method achieves the continuously variable Mach-number flow during a wind tunnel running.
文摘Peace is a key concept in the Jewish tradition; it has a long history. It is also an extremely broad concept. The present article takes on the subject of contemporary peace between Israel and her neighbors, addressing the issue from the vantage point of Judaism. While opinions on many issues are divided in Judaism today, all streams within the Jewish tradition uphold the concept of peace. Even so, each stream supports a somewhat different version of this ideal, subject to different limitations or reservations. One of the most serious challenges which Judaism today faces in connection with the State of Israel is the issue of exchanging territories for peace. The goal of the present paper is to show that while most approaches rooted in traditional Judaism have opposed such an exchange, Israel's religious political parties have endorsed it, advancing different arguments in support of their view. The method followed in the present paper is to study the arguments which have been used in support of peace agreements based on return or exchange of land. In light of the arguments put forth in the paper, to be counted among the accomplishments is a greater degree of openness--even on the part of the religious sector in Israel--toward the effort to achieve peace between Israel and her neighbors.
基金Supported by the National High Technology Research and Development Programme of China(No.2015AA015405)
文摘Social media like Twitter who serves as a novel news medium and has become increasingly popular since its establishment. Large scale first-hand user-generated tweets motivate automatic event detection on Twitter. Previous unsupervised approaches detected events by clustering words. These methods detect events using burstiness,which measures surging frequencies of words at certain time windows. However,event clusters represented by a set of individual words are difficult to understand. This issue is addressed by building a document-level event detection model that directly calculates the burstiness of tweets,leveraging distributed word representations for modeling semantic information,thereby avoiding sparsity. Results show that the document-level model not only offers event summaries that are directly human-readable,but also gives significantly improved accuracies compared to previous methods on unsupervised tweet event detection,which are based on words/segments.
文摘This research serves the primary purpose to support the reform of administration budgets for Taiwan Residents universities to optimize their document processing system. The main research method applied is quantitative analysis to explore the relationships between document quantity and each administration spending. The research observes that Taiwan Residents universities in general rely more on electronic systems to manage documents. Therefore, as proven by correlation test and regression model, personnel spending and miscellaneous spending are the only two categories which can help predict document flows. However, only miscellaneous spending is positively related to document quantity, so this category should be allocated with more funding. Personnel spending, on the contrary, should be less. For the long-term budgeting strategy, Taiwan Residents universities should begin with discovering problems from the existing system, design an allocation plan, execute the plan, and finally evaluate the outcomes. This project is on the first to explore the new academic research field which relates to logistics, budgeting, and university administration.
文摘The peer-to-peer(P2P) file-sharing network as a vehicle of disseminating files has become very popular. The appearance of dozens of kinds of passive worms on this network has, however, made it unsecured. This problem has been paid attention and a few of models for passive worm propagation has been presented. Unfortunately, the dynamic properties of this network are ignored in these models. Given the fact, the characteristics of both this network and the passive worm are identified, and on this basis a new mathematical model of passive worm propagation on the P2P network is presented in applying epidemiology in this paper. Note that the dynamic properties of this network are considered in the presented model. The model has been validated by large scale simulation experiments, which demonstrates that the presented model may be used for analyzing the behaviors of passive worms and predicting the trend of their propagation.
基金Supported by China Postdoctoral Science Foundation under Grant No.20090460102 Zhejiang Province Postdoctoral Science Foundation,National Key Basic Research Program of China under Grant No.2004CB318000 National Natural Science Foundation of China under Grant No.10871170
文摘In physics,the Klein-Gordon equation describes the motion of a quantum scalar or pseudoscalar field.Itis important to find actual values of its solutions in general timespace manifold.The paper deals with description ofdiscrete exterior calculus method for solving this equation numerically on space manifold and the time.The analysis ofstable condition and error for this method is also accomplished.
基金Under the auspices of Fellowship for Young International Scientists of Chinese Academy of Sciences(No.2010Y12A10)
文摘Hydrological processes in river basins of similar size and morphology may differ significantly due to different climatic conditions. This paper presents a comparative analysis of hydrological characteristics of two river basins located in different climatic zones: the Wisok River Basin in the south-eastern Poland and the Chaohe River Basin in the northern China. The criteria of their choice were similarities in the basin area, main river length and topography. The results show that climate plays a key role in shaping fluvial conditions within the two basins. It is concluded that: 1) precipitation in the Wisok River Basin is more evenly distributed in the yearly cycle, while in the Chaohe River Basin it is highly concentrated in the few summer months; 2) spring snowmelt significantly contributes to runoff in the Wisok River Basin, while its role in the Chaohe River Basin is negligible; 3) in the Wisok River Basin, besides the peak flow in spring, there is also a period of high water in summer resulting from precipitation, while in the Chaohe River Basin there is only one high water period in summer; 4) the Wisok River Basin shows relatively higher stability in terms of the magnitude of intra- and inter-seasonal discharges; 5) during the multi-year observation period, a decrease in both precipitation and runoff was recorded in the two river basins.
基金National Natural Science Foundations of China (No. 50833002, No. 20774018)
文摘Hybrid organic-inorganic polymer nanocomposites incorporating organically modified montmorillonite (MMT) and ultra-high molecular weight polyethylene (UHMWPE) were examined. UHMWPE/MMT hybrid nanocomposites were prepared using gel and pressure-induced flow(PIF) processing methods at a gel weight concentration of 8% UHMWPE with various organoclay contents (0, 0.4, 0.8, 1.2, and 1.6 parts per hundred parts). The interlayer properties of the nanocomposites were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The thermal and mechanical interfacial properties of the nanocomposites were investigated through thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and the use of a universal test machine (UTM). TEM indicates that the nanocomposites are formed upon dispersion of MMT in the polymer matrix. From the DSC, TGA, and DMA results, we find that the thermal stability of the UHMWPE nanocomposites increases as the MMT content increases. The nanocomposites show higher tensile strengths than pure UHMWPE gel sheet. These findings indicate that the interfacial and mechanical properties are improved by the addition of MMT and PIF processing.
文摘In this study, the authors experimentally investigated the changes of the mean velocity component profiles, half-widths (b12), turbulence intensities, Reynolds shear stress and intermittency of turbulence of a transient plane turbulent jet developing from a jet exit into a hood opening. The values of maximum mean-velocity and half-widths of the axial velocity profile along the center-line of the jet are greater than those for a fully developed two-dimensional jet. Turbulence intensity in the axial direction is not affected by the flow rate ratio. At the same time, turbulence intensity in the lateral direction becomes greater as the hood is approached and the flow rate ratio Q3/Q1 becomes larger (QI is jet flow rate from nozzle and Q3 is suction flow rate produced by the hood). These experimental results are in accord with the distributions of production terms in the axial and lateral directions. Reynolds shear stress becomes smaller as the flow rate ratio becomes larger near the hood. Dimensionless distance y1/br2, from the center axis of the flow to the point where intermittency factor y becomes a constant value, narrows as the flow rate ratio becomes larger near the hood.
文摘The influences due to several AVIs (airfoil-vortex interactions) are studied by using a two-dimensional CFD (computational fluid dynamics) method. The primary goal of this effort is to assess the variation of vortex center location and vortex circulation associated with sequential AVI toward an improvement of the hybrid method of CFD and prescribed wake model, which closely relates to predicting the BVI (blade-vortex interaction) noise radiated from a helicopter rotor. The representative of sequential AVI is performed by single vortex and two airfoils. Investigations with respect to vortex center location and vortex circulation after AVIs have been made by varying the miss-distance, which is the vertical distance between the airfoil leading edge and the vortex center. Correlations between miss-distance and vorticity field show that there exists complicated vortex wake flow with several vortices newly induced in 1st AVI. The pressure fluctuation amplitude clarifies that the intensity in 2nd AV1 is significantly low compared to the intensity in 1st AVI due to the influence of vortex dissipation. Simulations turned out to modify the vortex center location represented by the hybrid method using an offset value for a streamwise direction and to dissipate the vortex circulation for improving the accuracy of BVI noise prediction.
文摘This paper provides an overview of the state of art of reverse logistics and current status of waste management problems with special emphasis on developing countries. Logistics activities have been practiced and played a fundamental role in the global economic development for over 5,000 years. It has then been transformed into different logistics branches and elaborates the emergency of reverse logistics as one of the most important. The paper presents the evolution of logistics into reverse logistics and how it relates to waste management both in the developed and developing world. Reverse logistics is a relatively new phenomenon in the research area which is mainly referring to damaged goods, the take back of products that should be returned to the manufacturers or distributors. Reverse logistics is relatively more practiced in an organized way in the developed world than in the developing countries in that the latter provided less value additions on reversed products.
基金supported by the National Natural Science Foundation of China(Grant Nos.41106012,41176008,91028008)a grant from Sanya Institute of Deep-Sea Science and Engineering(Grant No.SIDSSE-201207)
文摘Based on high-resolution,Array for Real-time Geostrophic Oceanography(Argo)profiles and Sea Level Anomaly(SLA)data,this study statistically analyzes and compares turbulent diapycnal mixing profiles inside and outside mesoscale eddies in the Gulf Stream region.The result indicates that average diapycnal diffusivity at 300–540 m depths in anticyclonic eddies reaches4.0×10-5 m2 s-1.This is significantly higher than the 1.6×10-5 m2 s-1 outside eddies and 0.8×10-5 m2 s-1 in cyclonic eddies.Probabilities of diapycnal diffusivity greater than 10-4 m2 s-1 within anticyclonic and cyclonic eddies and outside eddies are29%,5%and 12%,respectively.However,magnitudes of average diapycnal diffusivity at 540–900 m depths in these three cases are of the same order,10-5 m2 s-1.Twenty-four of a total 38 anticyclonic eddies had enhanced mixing in the ocean interior,and 22 were observed during or shortly after strong winds.The coincidence between enhanced mixing and strong wind stress indicates that more wind-induced,near-inertial wave energy propagates downward in anticyclonic eddies.The deeper part of 12 profiles(below 540 m)in anticyclonic eddies had vertical overturns with Thorpe scale exceeding 5 m,among which three profiles had overturns reaching 20 m.Enhanced mixing may have occurred in deep layers of some profiles,although it was not evident in average conditions.
基金supported by the Technology Agency of the Czech Republic under the grant TA03020277by the Czech Science Foundation under grant P101/12/1271
文摘The contribution deals with the experimental and numerical investigation of compressible flow through the tip-section turbine blade cascade with the blade 54″ long. Experimental investigations by means of optical(interferometry and schlieren method) and pneumatic measurements provide more information about the behaviour and nature of basic phenomena occurring in the profile cascade flow field. The numerical simulation was carried out by means of the EARSM turbulence model according to Hellsten [5] completed by the bypass transition model with the algebraic equation for the intermittency coefficient proposed by Straka and P?íhoda [6] and implemented into the in-house numerical code. The investigation was focused particularly on the effect of shock waves on the shear layer development including the laminar/turbulent transition. Interactions of shock waves with shear layers on both sides of the blade result usually in the transition in attached and/ or separated flow and so to the considerable impact to the flow structure and energy losses in the blade cascade.