56 research outputs found
Spatial and temporal variations of organochlorine pesticides (OCPs) in water and sediments from Honghu Lake, China
No full textHonghu Lake in Jianghan Plain, central China is an important habitat for many migratory birds and an important site for freshwater fishery, and Honghu Lake region is also a main area for rice and cotton production in China. To understand the status and changes of organochlorine pesticide (OCP) contamination, and to assess the OCPs' risks for the ecosystem in Honghu Lake, thirty surface water samples, fifteen surface sediments, and a sediment core were collected in January and July, 2005. OCPs, such as DDTs, HCHs and chlordanes, were determined by GC-ECD in all samples. Concentrations of OCPs in surface water collected during the wet season (July 2005) were relatively higher than those collected during the dry season (January 2005), indicating that the increasing land runoff during the summer might bring the chemical residues from soils to Honghu Lake. The relatively low alpha-HCH/gamma-HCH ratio and the relatively high o,p'-DDT/p,p'-DDT ratio indicated the application of lindane on regional agricultural lands in late spring and summer (April-August), which increased the increasing contribution of dicofol to DDT in Honghu Lake, respectively. The levels of Sigma HCHs and Sigma DDTs in the surface sediments were relatively lower than those from the Yangtze River Delta, but comparable to those from other lakes and rivers in China. The composition of HCHs and DDTs in the surface sediments showed that there was fresh input of lindane (gamma-HCH), and DDT residues in Honghu Lake were aged and probably mainly originated from weathered agricultural soils of surrounding Jianghan Plain. Wash out of HCHs and DDTs from soil was the possible process which caused the increasing concentrations of these chemicals in recent years. (C) 2013 Elsevier B.V. All rights reserved.Honghu Lake in Jianghan Plain, central China is an important habitat for many migratory birds and an important site for freshwater fishery, and Honghu Lake region is also a main area for rice and cotton production in China. To understand the status and changes of organochlorine pesticide (OCP) contamination, and to assess the OCPs' risks for the ecosystem in Honghu Lake, thirty surface water samples, fifteen surface sediments, and a sediment core were collected in January and July, 2005. OCPs, such as DDTs, HCHs and chlordanes, were determined by GC-ECD in all samples. Concentrations of OCPs in surface water collected during the wet season (July 2005) were relatively higher than those collected during the dry season (January 2005), indicating that the increasing land runoff during the summer might bring the chemical residues from soils to Honghu Lake. The relatively low alpha-HCH/gamma-HCH ratio and the relatively high o,p'-DDT/p,p'-DDT ratio indicated the application of lindane on regional agricultural lands in late spring and summer (April-August), which increased the increasing contribution of dicofol to DDT in Honghu Lake, respectively. The levels of Sigma HCHs and Sigma DDTs in the surface sediments were relatively lower than those from the Yangtze River Delta, but comparable to those from other lakes and rivers in China. The composition of HCHs and DDTs in the surface sediments showed that there was fresh input of lindane (gamma-HCH), and DDT residues in Honghu Lake were aged and probably mainly originated from weathered agricultural soils of surrounding Jianghan Plain. Wash out of HCHs and DDTs from soil was the possible process which caused the increasing concentrations of these chemicals in recent years. (C) 2013 Elsevier B.V. All rights reserved
On Fields Synergism and Convective Heat Transfer Enhancement and Control in Centrifugal Force Field
No full textSongs and legends in Shi ji in the late Qin and the early Han era : Stories with songs on Jing Ke, Xiang Yu, Liu Bang and Empress Lu
No full textSongs in Shi Ji or Records of a Historian, example for Xiang Yu's Gaixia Ge 垓下歌, and Liu Bang's Dafeng Ge 大風歌, are commonly regarded as the expression of singer's feelings. They are placed in the dramatic scenes, the characters similarly shed tears after singing. In spite of high spirits, the descriptions of these scenes are stereotyped. They are not so much historical records as legends or stories, the songs also are not so much independent literary works as inseparable parts of the stories. In Shi Ji, songs bring fatal changes to the characters, and lead them to their ruin. Jing Ke's Yishui Ge 易水歌 and Xiang Yu's Gaixia Ge are typical examples. Liu Bang's Dafeng Ge appears an exception, but after this song, Liu Bang's fortune had begun to take a turn for the worse, and it came to the surface at his Honghu Ge 鴻鵠歌. All these songs has to do with Heaven, expresses human's struggle against their fortune. Empress Lu was a tyrant, who did not struggle against Heaven but ignored it, so she had never sung a song and died by wrath of Heaven
Experimental Investigation on Infrared Signatures of Axisymmetric Vectoring Exhaust Nozzle With Film Cooling and Low-Emissivity Coating
No full textInvestigations on infrared (IR) radiation suppression of axisymmetric vectoring exhaust nozzle (AVEN) are meaningful, due to the requests for maneuverability and IR stealth capability of aircrafts. In this paper, the synthetic suppression scheme of film cooling and low-emissivity coating was adopted on the center body and divergent flaps of the nozzles at 0 deg, 10 deg, and 20 deg vectoring angles. The IR signatures of both the baseline AVEN and the nozzles with IR suppression were measured. Comparing the IR signatures of the nozzles with and without IR suppression measures, the IR suppression effectiveness of the film cooling and low-emissivity coating was obtained. The investigation results indicate that the IR signatures of AVEN decrease with the increase of vectoring angle. The film cooling enables a remarkable decrease of the IR signatures of AVEN. The synthetic suppression of film cooling and low-emissivity coating enables a further decrease of IR signatures. For the case studied in this paper, the integrated radiation intensities of the nozzles with film cooling and low-emissivity coating at 0 deg, 10 deg, and 20 deg vectoring angles are decreased by 52.3%, 57.9%, and 37.2% at 0 deg measurement angle, respectively.</jats:p
Investigation on Infrared Signature of Axisymmetric Vectoring Exhaust System with Infrared Suppressions
No full textNumerical Study of the Effect of Blowing Angle on Cooling Effectiveness of an Effusion Cooling
No full textA Turbulent Inflow Generation Method for the LES of High Re Flow by Scaling Low Re Flow Data
No full textThe rescaling–recycling method (RRM) is usually used to generate turbulent inflow for the LES of compressible wall-bounded flows, which can lead to relatively high computational cost for high Re flows since the mesh resolution increases exponentially with Re number. A turbulent inflow generation method based on the scaling of low Re flow, referred as TIG-LowRe, is proposed, aiming at reducing the computational cost when applying the RRM. To validate the proposed method, the TIG-LowRe method was applied to generate turbulent inflow for the LES of a non-isothermal round jet flow at Re = 86,000. Two cases were carried out with the inflow generated based on two round pipe flows at Re = 10,000 and 24,000. The results show that the mean and fluctuating temperatures of the two cases agree well with the experimental data. In the case of low Re flow at Re = 10,000, the jet flow decays too fast along the axial direction, the mean and fluctuating axial velocities are over-predicted and the radial fluctuating velocity is under-predicted. By increasing the Re of the low Re flow to 24,000, the decay rate of the jet flow decreases and the accuracies of the mean and fluctuating axial velocities are obviously improved, while the radial fluctuating velocity shifts further away from the experimental data. The main reason for the difference between the two cases is that more fine turbulent structure of the inflow in case-Re10000 is lost than in case-Re24000 during the turbulence generation process
Optimal Design of Ejector Nozzle Profile with Internal and External Integrated Flow
No full textBased on the orthogonal experimental method, a simulation case of the flow field of the ejector nozzle was designed to investigate the influence of the structural parameters of the ejector nozzle on the internal and external flow. This study explored the effects of throat area, outlet area, throat position, and ejector nozzle length on the ejector flow rate ratio, thrust coefficient, and net thrust coefficient. Subsequently, flow path geometry optimization was conducted to maximize the thrust coefficient or net thrust coefficient. The results revealed that the throat area ratio and the outlet area of the ejector nozzle are the primary factors affecting the aerodynamic performance. Compared to the baseline ejector nozzle model, the optimal model for thrust coefficient exhibited a 16.333% improvement, while the optimal model for net thrust coefficient demonstrated a significant enhancement of 46.674%
Numerical Investigation of Flow and Heat Transfer Characteristics in Plate with Multiple Incline Stage Holes
No full textIn this paper, the effects of impingement and film composite cooling on the design of combustion chamber cooling structure are simulated by numerical simulation. The focus of the investigation was on increased film cooling efficiency and enhanced heat transfer between the coolant and the hole wall. The five-stage shaped hole model and one cylindrical hole design have the same equivalent flow area. The flow and heat transfer characteristics of cylindrical hole and stage-shaped hole were numerically investigated under same blowing ratio, and compared at the same blowing ratio. The results showed the stage-shaped hole resulted in higher cooling effectiveness, especially in rear part, and the mechanisms of which were studied in details. The consequences of the phase parameters in the flow have very clearly dependedt on the internal shape of the corresponding hole. Stage-shaped holes formed impact inside the wall, tapped the coolant potential in cooling, and increased the heat transfer inside the solid wall. Further, stage-shaped hole resulted in unstabilized flow inside hole, gave an enhancement of lateral spreading ability, and brought a significant increase of the film lateral effectiveness. Further, the affection of area ratio and height ratio has been studied by five models. The results show that the increasing of area ratio leads to an increase in cooling efficiency, which also indicates the increasing of height ratio showed slight affection
「史記」にみえる秦末漢初の歌と傳說 : 荊軻・頂羽・劉邦・呂后をめぐる歌物語
No full textSongs in Shi Ji or Records of a Historian, example for Xiang Yu's Gaixia Ge 垓下歌, and Liu Bang's Dafeng Ge 大風歌, are commonly regarded as the expression of singer's feelings. They are placed in the dramatic scenes, the characters similarly shed tears after singing. In spite of high spirits, the descriptions of these scenes are stereotyped. They are not so much historical records as legends or stories, the songs also are not so much independent literary works as inseparable parts of the stories. In Shi Ji, songs bring fatal changes to the characters, and lead them to their ruin. Jing Ke's Yishui Ge 易水歌 and Xiang Yu's Gaixia Ge are typical examples. Liu Bang's Dafeng Ge appears an exception, but after this song, Liu Bang's fortune had begun to take a turn for the worse, and it came to the surface at his Honghu Ge 鴻鵠歌. All these songs has to do with Heaven, expresses human's struggle against their fortune. Empress Lu was a tyrant, who did not struggle against Heaven but ignored it, so she had never sung a song and died by wrath of Heaven
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