Hester-Dendy (HD) multi-plate samplers have been widely used by state and federal government agencies for bioassessment of water quality through use of macroinvertebrate community data. To help guide remediation and r...Hester-Dendy (HD) multi-plate samplers have been widely used by state and federal government agencies for bioassessment of water quality through use of macroinvertebrate community data. To help guide remediation and restoration efforts at the Niagara River Great Lakes Area of Concern site, a multi-agency study was conducted in 2014 to assess the contribution of seven major urban tributaries on the US side of the river toward the impairment of the Niagara River. As part of this study, macroinvertebrate communities were sampled using two co-located versions of HD samplers: one version used by the New York State Department of Environmental Conservation (NYSDEC) and another by the US Environmental Protection Agency Office of Research and Development. Samplers were deployed in tributaries in highly developed watersheds with high percent impervious surface. The two sampling methods varied in terms of number and size of plates, between-plate spacing, and deployment method. Comparison of the similarity/grouping of communities with multivariate ordination techniques, Nonmetric Multidimensional Scaling and Multi-Response Permutation Procedure, showed that both methods were able to detect differences in communities at stations, despite some grouping by month and method. The indices and metrics derived from the two HD methods were found to give comparable but not identical assessments of water quality. Despite their differences, the methods were robust with respect to water quality categories derived from indices used nationally (HBI) and by NY state (BAP). For the common richness metrics, total taxa and EPT richness, there was no statistical difference between means from 3 samplings. Some metrics, especially percent tolerant collector-gatherer individuals, did show significant differences at certain stations. Indicator Species Analysis showed some taxa associated with each method. The observed community differences were thought mostly due to the difference in sampler deployment position. .展开更多
Polyurethane foam（PUF）passive samplers were deployed and tree bark samples were collected at 15 sites across western China in 2013,and the organochlorine pesticide（OCP）concentrations in the samples were determined...Polyurethane foam（PUF）passive samplers were deployed and tree bark samples were collected at 15 sites across western China in 2013,and the organochlorine pesticide（OCP）concentrations in the samples were determined.Dichlorodiphenyltrichloroethane and its degradation products（collectively called DDTs）,hexachlorocyclohexanes（HCHs）,and hexachlorobenzene（HCB）were the dominant OCPs in the PUF samples and tree bark samples.The mean DDTs,HCHs and HCB concentrations were 33,22 and 18 ng/sample in the PUF samples,and 428,74,and 43 ng/（g lipid weight（lw））in the tree bark,respectively.The OCP concentrations in the air,calculated using PUF–air and tree-bark–air partitioning models,were of the same order of magnitude.Both sample types showed that relatively fresh inputs of DDT and HCHs to the environment have occurred in western China.Meanwhile,PUF passive samplers were compared with the use of tree bark samples as passive samplers.The OCP compositions in the PUF and tree bark samples were different.Only the relatively stable OCPs（such as HCB,β-HCH and p,p′-dichlorodiphenyldichloro-ethylene（DDE））were consistent in the PUF and tree bark samples.展开更多
In this paper,the structure of 'double juts' soil sampler and a series of new soil samplers are introduced.The internal diameter of auger tip the sampler is less than that of sampling tube, but the external di...In this paper,the structure of 'double juts' soil sampler and a series of new soil samplers are introduced.The internal diameter of auger tip the sampler is less than that of sampling tube, but the external diameterof auger tip is larger than that of sampling tube. Therefore, adhesion and cutting resistance can be reducedby limiting connection areas between sampler and the soil. Such a new structure makes it possible to bewidely used for the production of a series of special soil samplers.展开更多
Passive sampling for the monitoring of organic pollutants (PAHs, PCBs, PBDEs) in ambient air has received increased attention in the last two decades. However, the accuracy of the concentration of organics obtained wi...Passive sampling for the monitoring of organic pollutants (PAHs, PCBs, PBDEs) in ambient air has received increased attention in the last two decades. However, the accuracy of the concentration of organics obtained with passive samplers under varying environmental conditions is a subject of controversy. In this study, effect of ambient temperature on passive samplers was evaluated by using three different sampler configurations. Additionally, passive samplers with polyurethane disks (PUF) were applied throughout the Island for the determination of the airborne concentration of polycyclic aromatic hydrocarbons (PAHs). The passive samplers were deployed in seven municipalities for three-month periods in two different sampling campaigns, representing hurricane and non-hurricane seasons. Here we present preliminary results obtained from those sampling campaigns. The total concentrations of 15 PAHs varied from 3.1 to 19.6 and from 5.5 to 38.5 ng/m3 for hurricane and non-hurricane seasons, respectively. Hurricane and non-hurricane season concentrations of PAH were significantly different for the samples taken in the northern municipalities of the Island. However, there was no significant difference in PAH concentrations between the hurricane and non-hurricane seasons for the southern sites. Increased rainfall and high-relative humidity during the hurricane season had an influence on the concentrations of PAHs derived by the passive PUF sampler.展开更多
Efforts have increased to measure nitrate losses from farmland under different management practices due to environmental and public concerns over levels of nitrate-nitrogen (NO<sub>3</sub>-N) in surface an...Efforts have increased to measure nitrate losses from farmland under different management practices due to environmental and public concerns over levels of nitrate-nitrogen (NO<sub>3</sub>-N) in surface and ground waters. This study evaluated the effect of conventional tillage (CT) and strip tillage (ST) practices and three N application rates on NO3-N concentrations in soil water at a 76 cm depth under irrigated sugarbeet (Beta vulgaris L.) in a clay loam soil. Nitrogen rates were applied as dry urea at 120, 150, 180 kg N ha-1</sup> in 2006;130, 160, 190 kg N ha-1 in 2007;and 110, 140, 170 kg N ha<sup>-1</sup> in 2008. Soil water volumes were measured weekly during each growing season using three ceramic suction cup samplers per plot placed at a 76 cm depth below the soil surface under each tillage. Results indicated that NO<sub>3</sub>-N concentrations at the 76 cm depth in the soil profile were not significantly affected by either tillage practice or by N application rate due to soil variability across the field and due to suction cup samplers’ biased estimate of soil water. The three N rates under CT and ST practices maintained NO<sub>3</sub>-N concentrations below the root zone to levels exceeding the 10 mg L<sup>-1</sup> safe drinking water maximum level in all three years. There were large variations in NO<sub>3</sub>-N concentrations among replicates within each tillage and N rate that were likely caused by variability in soil physical, hydraulic and chemical properties that impacted water movement through the soil profile, N dynamics and leaching below the root zone of sugarbeet. In conclusion, suction cup samplers are point water measurement devices that reveal considerable variability among replicates within each treatment due to the heterogeneity of field soils. Further, these samplers are not recommended in heterogeneous soils with preferential flow characteristics.展开更多
Measurements of gaseous SO2, NO, NO2, H2S, O3, NH3 and VOCs, in Kuwait city using IVL passive sampler technology, were obtained on monthly basis during the period from March 2011 to February 2012 at 10 locations. The ...Measurements of gaseous SO2, NO, NO2, H2S, O3, NH3 and VOCs, in Kuwait city using IVL passive sampler technology, were obtained on monthly basis during the period from March 2011 to February 2012 at 10 locations. The results of this study reveal that those compounds had low concentrations compared to Kuwait Environment Public Authority standards for residential areas. It is found that nitrogen oxides, benzene and xylene were mostly emitted from motor vehicles;in contrast, industrial sources including oil industries were a major contributor to sulfur dioxide and toluene pollution. Higher concentrations of NOx and SO2?were recorded during winter season where the inversion layer is quite pronounced thus trapping more pollutants in ambient air, while higher O3 values were recorded in summer period;the hot season in Kuwait. The spatial distributions of the measured gaseous air pollutants were extremely consistent with the influence of the prevailing wind direction NW. In general and except for PM10, the yearly average air quality indices (AQI) of SO2, NO2, CO and O3?concentrations are coming under the category of “good” and “moderate”.展开更多
The purpose of this study is to verify an 1D multi-plate heat-transfer model estimating the temperature distribution on the interface between polymer electrolyte membrane and catalyst layer at cathode in single cell o...The purpose of this study is to verify an 1D multi-plate heat-transfer model estimating the temperature distribution on the interface between polymer electrolyte membrane and catalyst layer at cathode in single cell of polymer electrolyte fuel cell, which is named as reaction surface in this study, with a 3D numerical simulation model solving many governing equations on the coupling phenomena in the cell. The results from both models/simulations agreed well. The effects of initial operation temperature, flow rate, and relative humidity of supply gas on temperature distribution on the reaction surface were also investigated. It was found in both 1D and 3D simulations that, the temperature rise （i.e., Treact-Tini） of the reaction surface from initial operation temperature at 70℃ was higher than that at 80℃ irrespective of flow rate of supply gas. The effect of relative humidity of supply gas on Treact- Tini near the inlet of the cell was small. Compared to the previous studies conducted under the similar operation conditions, the Treact - Tini calculated by 1D multi-plate heat-transfer model in this study as well as numerical simulation using 3D model was reasonable.展开更多
To accurately acquire deep-sea live biological samples,a hydraulic suction macro-biological pressure-retaining sampler(HSMPS)was designed to achieve active capture of seafloor biological by a suction pump.The complex ...To accurately acquire deep-sea live biological samples,a hydraulic suction macro-biological pressure-retaining sampler(HSMPS)was designed to achieve active capture of seafloor biological by a suction pump.The complex flow fields of deep-sea biologicals at three different locations were simulated.The deep-sea biologicals cause the flow field pressure and velocity to rise at different locations of the sampler,and the magnitude of the rise varies at different locations.The internal flow properties of the sampler were analyzed for different pumping flow rates the sampler.When the flow rate of the sampler pump was greater than 14 m3/h,the velocity of the inlet of the inflow area was greater than the limiting velocity of the deep-sea biologicals.The pumping test of deep-sea biologicals pumping sampler was carried out in the laboratory,and the test results were basically consistent with the simulation analysis.In order to balance the deep-sea biologicals damage and escape rate,the pumping flow of the sampler should be controlled between 14 and 16 m3/h.The test results provide a theoretical basis for the design of deep-sea biologicals sampling equipment.展开更多
The concentration of short-chain polychlorinated paraffins(SCCPs) in the urban air of Dalian,China was monitored from September 2016 to August 2017 with a self-developed passive sampler(PAS1) and an active high-volume...The concentration of short-chain polychlorinated paraffins(SCCPs) in the urban air of Dalian,China was monitored from September 2016 to August 2017 with a self-developed passive sampler(PAS1) and an active high-volume sampler, simultaneously. PAS1 successfully collected the entire target SCCPs in the ambient air. Air SCCPs sampled by PAS1 were found be in the linear uptake stage during 181 days of sampling. Passive and active samples showed comparable congener profiles, and the dominant contributors of SCCPs in the two kinds of samples were similar. A significant linear correlation was observed between the total concentration of SCCPs sampled by PAS1 and active sampler in the four seasons. The passive sampling rates of the PAS1 for the gas and particulate phases of SCCPs were measured. The quantitative structure–property relationship of the sampling rate of PAS1(Rair) for gas-phase SCCPs was studied. From the molecular point of view, Rairwas mainly affected by the molecular weight and sub-cooled liquid vapor pressure of SCCPs. In general, SCCPs in the urban air of Dalian mainly existed in gas phase,lower molecular weight SCCPs primarily occurred in the gas phase, whereas higher molecular weight SCCPs were predominately adsorbed or absorbed on airborne particles. The air concentration of SCCPs in the four seasons were different, the correlation of the concentration of SCCPs in the air with the meteorology parameters was conducted. The exposure risk by intake air SCCPs of the residents around the sampling sites was evaluated according to the European risk assessment standards.展开更多
Submarine hydrothermal vents occur over a wide depth range from a few meters to several thousands of meters. Most existing hydrothermal fluid samplers are focused on deep-sea environments and are not suited for collec...Submarine hydrothermal vents occur over a wide depth range from a few meters to several thousands of meters. Most existing hydrothermal fluid samplers are focused on deep-sea environments and are not suited for collecting shallow-water fluids. In this study, a new gas-tight sampler which can be easily deployed by both submersibles and scuba divers to collect fluid samples from both deep-sea and shallow-water hydrothermal vents is presented. The proposed sampler uses an electric control sampling valve for fluid collection and a system to measure and display the temperature of the hydrothermal fluid while sampling. It is capable of working in manual mode to be controlled via external signals, or in automatic mode to collect a fluid sample according to the temperature. The master-slave architecture of the electronic system makes the sampler flexible in meeting many different deployment requirements. The performance of the sampler has been demonstrated by preliminary field tests at a shallow-water hydrothermal vent site.展开更多
The hadal zone(ocean depths of 6 – 11 km) is one of the least-understood habitats on Earth because of its extreme conditions such as high pressure, darkness, and low temperature. With the development of deep-sea vehi...The hadal zone(ocean depths of 6 – 11 km) is one of the least-understood habitats on Earth because of its extreme conditions such as high pressure, darkness, and low temperature. With the development of deep-sea vehicles such as China's 7000 m manned submersible Jiaolong, abyssal science has received greater attention. For decades, gravity-piston corers have been widely used to collect loose subsea-sediment long-core samples. However, the weight and length of the gravity sampler cables and the operating environment limit sampling capacity at full ocean depths. Therefore, a new self-floating sediment sampler with a spring-loaded auto-trigger release and that incorporates characteristics from traditional gravity-driven samplers is designed. This study analyzes the process by which a gravity-piston corer penetrates the sediment and the factors that affect it. A formula for obtaining the penetration depth is deduced. A method of optimizing the sampling depth is then developed based on structure design and parametric factor modeling. The parameters considered in the modeling include the sampling depth, balance weight, ultimate stress friction coefficient, dimensions of the sampler, and material properties. Thus, a new deep-sea floating parametric sampler designed based on virtual prototyping is proposed. Accurate values for all the design factors are derived from calculations based on the conservation of energy with penetration depth, analyses of the factors affecting the penetration depth, and analyses of the pressure bar stability. Finally, experimental data are used to verify the penetration-depth function and to provide theoretical guidance for the design of sediment samplers.展开更多
The issues of how to quickly collect seawater samples and of how to make sure that those samples truly reflect the in-situ information on gas composition and concentration have therefore become a hot but difficult top...The issues of how to quickly collect seawater samples and of how to make sure that those samples truly reflect the in-situ information on gas composition and concentration have therefore become a hot but difficult topic in the field of ocean technology.Most conventional seawater samplers only focus on collecting seawater itself,but take little consideration on gas preservation.A set of new oceanographic tools are presented for ocean resource exploration such as hydrothermal sulfide and gas hydrate,and for investigations on the processes and mechanisms of marine physical,chemical and biological evolutions.A gas-tight deep-sea water sampling system（GTWSS） is designed for the collection of deep-sea geochemical samples.This set of tools mainly consists of a conductivity temperature depth profiler（CTD）,release devices and gas-tight deep-sea water samplers（GTWS）.The GTWS is able to hold the gases in deep-sea water samples tightly,providing in-situ information on gas contents in the seawater samples and can be deployed on a routine wire-deployed CTD sampler for multi-layer discrete sampling of gas-tight seawater.Sea trials are performed successfully in 2008 and 2009,on a research vessel named HaiYang Si Hao in South China Sea,with the deepest trial depth 3 930 m.GTWSS is capable of quickly sampling 12 discrete gas-tight seawater samples（8.3 L per sample） during its single deployment.The head space method is employed to separate the gases from the seawater samples immediately after recovery of the seawater samples on the vessel.Field geochemical analysis is carried out by gaseous hydrocarbon sensors and an infrared gas analyzer.Results show that the concentrations of CH4 and CO2 in the seawater sampled by GTWSS are higher than those sampled by general non-gas-tight water samplers,thus confirming the gas tightness of GTWSS.Seawater samples can be collected quickly by using GTWSS,and GTWSS can keep the samples＇ integrity quite well.展开更多
Heat exchanger networks(HENs)in separated plants can be simultaneously synthesized through process streams directly or intermediate fluids indirectly.However,the direct and indirect methods are studied separately in m...Heat exchanger networks(HENs)in separated plants can be simultaneously synthesized through process streams directly or intermediate fluids indirectly.However,the direct and indirect methods are studied separately in most existing researches.As the result,conventional designs are probably suboptimal,because optimal solutions may call for hybrid approach wherein direct and indirect integration methods are used synchronously.To circumvent this drawback aforementioned,we propose in this research a novel methodology to synthesize multi-plant HENs considering both direct and indirect approaches.The methodology employs a novel superstructure covering most potential topologies for both interplant and intra-plant heat integration.We also take into account multiple kinds of intermediate fluids for indirect integration and this has not been fully addressed in previous research.A mixed-integer nonlinear programming(MINLP)is formulated to optimize multi-plant HENs involving indirect and direct methods.One example from existing literature and one industrial problem are solved to demonstrate the methodology’s capability.展开更多
Aiming at the requirement of the full-ocean-depth(operating water depth 11000 m)manned submersible to carry out the gas-tight sampling operation of the abyss seabed sediment,a kind of full-ocean-depth carrier submersi...Aiming at the requirement of the full-ocean-depth(operating water depth 11000 m)manned submersible to carry out the gas-tight sampling operation of the abyss seabed sediment,a kind of full-ocean-depth carrier submersible mechanical hand-held,full-ocean-depth gas-tight sediment sampler(GTSS)with the function of pressure-retaining and coring is designed.Firstly,the volume change model of pressure compensator is established,and it is pointed out that the volume of pressure compensator is about 16.14%equal to the volume of gas-tight sediment sampler(GTSS).Secondly,the pressure compensator is analyzed and calculated,and the relationship between the precharge pressure of the pressure compensator,the nominal volume of the pressure compensator and the pressure holding effect of the gas-tight sediment sampler(GTSS)is studied.The results show that with the increase of gas precharge pressure in the pressure compensator,the final pressure of the sampler also increases.Under the same precharge pressure condition,the larger the nominal volume of the pressure compensator,the greater the final pressure of the sampler.Finally,the air tightness test method is designed by using the developed gas tightness sampler of the full-ocean-depth product,and the change of the final pressure in the gas tight sampler under different precharge pressure is observed.The test results are consistent with the simulation results,indicating the correctness of the pressure compensation system(PCS)model.展开更多
This paper describes the design, construction and preliminary test results for a gas-tight serial sampler intended to be deployed at seafloor for long-term operation to take time-series fluid samples from deep-sea env...This paper describes the design, construction and preliminary test results for a gas-tight serial sampler intended to be deployed at seafloor for long-term operation to take time-series fluid samples from deep-sea environments such as cold seeps, water column and hydrothermal vents. The serial sampler is a modular system that is based on independent and identical sampling modules, which are designed to collect six 160 ml gas-tight fluid samples maintained at high pressure to a depth of 4000 meters. With two working modes, the sampler can be deployed either with seafloor cabled observatory for remote control or as a stand-alone device for autonomous operation. A prototype of the instrument has been constructed and tested on the MARS cabled observatory for two months. The laboratory and field tests proved the success of the design and construction of the serial sampler, and indicated the potential for future ocean sciences.展开更多
Since the 1970s, the studies on the geography of enterprise have become increasingly concerned with the spatial evolution of an enterprises in the West developed countries. However, little attention has so far been g...Since the 1970s, the studies on the geography of enterprise have become increasingly concerned with the spatial evolution of an enterprises in the West developed countries. However, little attention has so far been given to the spatial evolution of an enterprise in China. With China's ongoing economy and political reforms, a number of fundamental changes of enterprise behavior have occurred. These changes have certainly important influences on the evolution of industrial location. Therefore, there is a need for examining the spatial evolution of an enterprise in China. The purpose of the paper is to review the mapjor models of both the growth,and associated spatial evolution of an enterprise, with an illustrative case study of the HeaVy Automobile Enterprise Group of China. The paper is organized by three parts. The first examines the spoilal groWth and location adjustment of multi-plant enterprise. The second reviews mapjor models of the spatial evolution of an enterprise. And the third analyzes the spatial evolution, over a period of time, of a representative sample of the Heavy Automobile Enterprise Group of China, and illustrates the findings with case studies. It is suggested that the models of spatial evolution of an enterprise would provide more evidence about micro-mechanism for evolution of micro- regional economic systems.展开更多
文摘Hester-Dendy (HD) multi-plate samplers have been widely used by state and federal government agencies for bioassessment of water quality through use of macroinvertebrate community data. To help guide remediation and restoration efforts at the Niagara River Great Lakes Area of Concern site, a multi-agency study was conducted in 2014 to assess the contribution of seven major urban tributaries on the US side of the river toward the impairment of the Niagara River. As part of this study, macroinvertebrate communities were sampled using two co-located versions of HD samplers: one version used by the New York State Department of Environmental Conservation (NYSDEC) and another by the US Environmental Protection Agency Office of Research and Development. Samplers were deployed in tributaries in highly developed watersheds with high percent impervious surface. The two sampling methods varied in terms of number and size of plates, between-plate spacing, and deployment method. Comparison of the similarity/grouping of communities with multivariate ordination techniques, Nonmetric Multidimensional Scaling and Multi-Response Permutation Procedure, showed that both methods were able to detect differences in communities at stations, despite some grouping by month and method. The indices and metrics derived from the two HD methods were found to give comparable but not identical assessments of water quality. Despite their differences, the methods were robust with respect to water quality categories derived from indices used nationally (HBI) and by NY state (BAP). For the common richness metrics, total taxa and EPT richness, there was no statistical difference between means from 3 samplings. Some metrics, especially percent tolerant collector-gatherer individuals, did show significant differences at certain stations. Indicator Species Analysis showed some taxa associated with each method. The observed community differences were thought mostly due to the difference in sampler deployment position. .
基金funded through the Minzu University of China fund for first-class university and first-class discipline construction projects(No.YLDX01013)the Institution of Higher Education Innovation Talent Recruitment Program(111 Program,No.B08044)+1 种基金the Minzu University Undergraduate Research Training Program(No.GCCX2013110034)the Fundamental Research Funds for the Central Universities(Nos.0910KYQN50,2015MDTD23C)
文摘Polyurethane foam（PUF）passive samplers were deployed and tree bark samples were collected at 15 sites across western China in 2013,and the organochlorine pesticide（OCP）concentrations in the samples were determined.Dichlorodiphenyltrichloroethane and its degradation products（collectively called DDTs）,hexachlorocyclohexanes（HCHs）,and hexachlorobenzene（HCB）were the dominant OCPs in the PUF samples and tree bark samples.The mean DDTs,HCHs and HCB concentrations were 33,22 and 18 ng/sample in the PUF samples,and 428,74,and 43 ng/（g lipid weight（lw））in the tree bark,respectively.The OCP concentrations in the air,calculated using PUF–air and tree-bark–air partitioning models,were of the same order of magnitude.Both sample types showed that relatively fresh inputs of DDT and HCHs to the environment have occurred in western China.Meanwhile,PUF passive samplers were compared with the use of tree bark samples as passive samplers.The OCP compositions in the PUF and tree bark samples were different.Only the relatively stable OCPs（such as HCB,β-HCH and p,p′-dichlorodiphenyldichloro-ethylene（DDE））were consistent in the PUF and tree bark samples.
文摘In this paper,the structure of 'double juts' soil sampler and a series of new soil samplers are introduced.The internal diameter of auger tip the sampler is less than that of sampling tube, but the external diameterof auger tip is larger than that of sampling tube. Therefore, adhesion and cutting resistance can be reducedby limiting connection areas between sampler and the soil. Such a new structure makes it possible to bewidely used for the production of a series of special soil samplers.
文摘Passive sampling for the monitoring of organic pollutants (PAHs, PCBs, PBDEs) in ambient air has received increased attention in the last two decades. However, the accuracy of the concentration of organics obtained with passive samplers under varying environmental conditions is a subject of controversy. In this study, effect of ambient temperature on passive samplers was evaluated by using three different sampler configurations. Additionally, passive samplers with polyurethane disks (PUF) were applied throughout the Island for the determination of the airborne concentration of polycyclic aromatic hydrocarbons (PAHs). The passive samplers were deployed in seven municipalities for three-month periods in two different sampling campaigns, representing hurricane and non-hurricane seasons. Here we present preliminary results obtained from those sampling campaigns. The total concentrations of 15 PAHs varied from 3.1 to 19.6 and from 5.5 to 38.5 ng/m3 for hurricane and non-hurricane seasons, respectively. Hurricane and non-hurricane season concentrations of PAH were significantly different for the samples taken in the northern municipalities of the Island. However, there was no significant difference in PAH concentrations between the hurricane and non-hurricane seasons for the southern sites. Increased rainfall and high-relative humidity during the hurricane season had an influence on the concentrations of PAHs derived by the passive PUF sampler.
文摘Efforts have increased to measure nitrate losses from farmland under different management practices due to environmental and public concerns over levels of nitrate-nitrogen (NO<sub>3</sub>-N) in surface and ground waters. This study evaluated the effect of conventional tillage (CT) and strip tillage (ST) practices and three N application rates on NO3-N concentrations in soil water at a 76 cm depth under irrigated sugarbeet (Beta vulgaris L.) in a clay loam soil. Nitrogen rates were applied as dry urea at 120, 150, 180 kg N ha-1</sup> in 2006;130, 160, 190 kg N ha-1 in 2007;and 110, 140, 170 kg N ha<sup>-1</sup> in 2008. Soil water volumes were measured weekly during each growing season using three ceramic suction cup samplers per plot placed at a 76 cm depth below the soil surface under each tillage. Results indicated that NO<sub>3</sub>-N concentrations at the 76 cm depth in the soil profile were not significantly affected by either tillage practice or by N application rate due to soil variability across the field and due to suction cup samplers’ biased estimate of soil water. The three N rates under CT and ST practices maintained NO<sub>3</sub>-N concentrations below the root zone to levels exceeding the 10 mg L<sup>-1</sup> safe drinking water maximum level in all three years. There were large variations in NO<sub>3</sub>-N concentrations among replicates within each tillage and N rate that were likely caused by variability in soil physical, hydraulic and chemical properties that impacted water movement through the soil profile, N dynamics and leaching below the root zone of sugarbeet. In conclusion, suction cup samplers are point water measurement devices that reveal considerable variability among replicates within each treatment due to the heterogeneity of field soils. Further, these samplers are not recommended in heterogeneous soils with preferential flow characteristics.
文摘Measurements of gaseous SO2, NO, NO2, H2S, O3, NH3 and VOCs, in Kuwait city using IVL passive sampler technology, were obtained on monthly basis during the period from March 2011 to February 2012 at 10 locations. The results of this study reveal that those compounds had low concentrations compared to Kuwait Environment Public Authority standards for residential areas. It is found that nitrogen oxides, benzene and xylene were mostly emitted from motor vehicles;in contrast, industrial sources including oil industries were a major contributor to sulfur dioxide and toluene pollution. Higher concentrations of NOx and SO2?were recorded during winter season where the inversion layer is quite pronounced thus trapping more pollutants in ambient air, while higher O3 values were recorded in summer period;the hot season in Kuwait. The spatial distributions of the measured gaseous air pollutants were extremely consistent with the influence of the prevailing wind direction NW. In general and except for PM10, the yearly average air quality indices (AQI) of SO2, NO2, CO and O3?concentrations are coming under the category of “good” and “moderate”.
文摘The purpose of this study is to verify an 1D multi-plate heat-transfer model estimating the temperature distribution on the interface between polymer electrolyte membrane and catalyst layer at cathode in single cell of polymer electrolyte fuel cell, which is named as reaction surface in this study, with a 3D numerical simulation model solving many governing equations on the coupling phenomena in the cell. The results from both models/simulations agreed well. The effects of initial operation temperature, flow rate, and relative humidity of supply gas on temperature distribution on the reaction surface were also investigated. It was found in both 1D and 3D simulations that, the temperature rise （i.e., Treact-Tini） of the reaction surface from initial operation temperature at 70℃ was higher than that at 80℃ irrespective of flow rate of supply gas. The effect of relative humidity of supply gas on Treact- Tini near the inlet of the cell was small. Compared to the previous studies conducted under the similar operation conditions, the Treact - Tini calculated by 1D multi-plate heat-transfer model in this study as well as numerical simulation using 3D model was reasonable.
基金Supported by National Key Research and Development Program of China(Grant Nos.2023YFC2809304,2022YFC2805904)National Natural Science Foundation of China(Grant No.52275106)Special Project for the Construction of Innovative City in Xiangtan of China(Grant No.ZX-ZD20221005).
文摘To accurately acquire deep-sea live biological samples,a hydraulic suction macro-biological pressure-retaining sampler(HSMPS)was designed to achieve active capture of seafloor biological by a suction pump.The complex flow fields of deep-sea biologicals at three different locations were simulated.The deep-sea biologicals cause the flow field pressure and velocity to rise at different locations of the sampler,and the magnitude of the rise varies at different locations.The internal flow properties of the sampler were analyzed for different pumping flow rates the sampler.When the flow rate of the sampler pump was greater than 14 m3/h,the velocity of the inlet of the inflow area was greater than the limiting velocity of the deep-sea biologicals.The pumping test of deep-sea biologicals pumping sampler was carried out in the laboratory,and the test results were basically consistent with the simulation analysis.In order to balance the deep-sea biologicals damage and escape rate,the pumping flow of the sampler should be controlled between 14 and 16 m3/h.The test results provide a theoretical basis for the design of deep-sea biologicals sampling equipment.
基金supported by the National Natural Science Foundation of China (No. 21577009)
文摘The concentration of short-chain polychlorinated paraffins(SCCPs) in the urban air of Dalian,China was monitored from September 2016 to August 2017 with a self-developed passive sampler(PAS1) and an active high-volume sampler, simultaneously. PAS1 successfully collected the entire target SCCPs in the ambient air. Air SCCPs sampled by PAS1 were found be in the linear uptake stage during 181 days of sampling. Passive and active samples showed comparable congener profiles, and the dominant contributors of SCCPs in the two kinds of samples were similar. A significant linear correlation was observed between the total concentration of SCCPs sampled by PAS1 and active sampler in the four seasons. The passive sampling rates of the PAS1 for the gas and particulate phases of SCCPs were measured. The quantitative structure–property relationship of the sampling rate of PAS1(Rair) for gas-phase SCCPs was studied. From the molecular point of view, Rairwas mainly affected by the molecular weight and sub-cooled liquid vapor pressure of SCCPs. In general, SCCPs in the urban air of Dalian mainly existed in gas phase,lower molecular weight SCCPs primarily occurred in the gas phase, whereas higher molecular weight SCCPs were predominately adsorbed or absorbed on airborne particles. The air concentration of SCCPs in the four seasons were different, the correlation of the concentration of SCCPs in the air with the meteorology parameters was conducted. The exposure risk by intake air SCCPs of the residents around the sampling sites was evaluated according to the European risk assessment standards.
基金Project supported by the National Natural Science Foundation of China （No. 41106081）, and the Science Fund for Creative Research Groups of the National Natural Science Foundation of China （No. 51221004）
文摘Submarine hydrothermal vents occur over a wide depth range from a few meters to several thousands of meters. Most existing hydrothermal fluid samplers are focused on deep-sea environments and are not suited for collecting shallow-water fluids. In this study, a new gas-tight sampler which can be easily deployed by both submersibles and scuba divers to collect fluid samples from both deep-sea and shallow-water hydrothermal vents is presented. The proposed sampler uses an electric control sampling valve for fluid collection and a system to measure and display the temperature of the hydrothermal fluid while sampling. It is capable of working in manual mode to be controlled via external signals, or in automatic mode to collect a fluid sample according to the temperature. The master-slave architecture of the electronic system makes the sampler flexible in meeting many different deployment requirements. The performance of the sampler has been demonstrated by preliminary field tests at a shallow-water hydrothermal vent site.
基金jointly supported by the Stable Supporting Fund of Science and Technology on Underwater Vehicle Technology (No. JCKYS2019604SXJQR-06)the National Natural Science Foundation of China-Marine Science Research Center of Shandong Provincial Government Joint Funding Project (No. U1606401)+3 种基金the National Natural Science Foundation of China (No. 61603108)the Taishan Scholar Project Funding (No. tspd20161007)the National Key Research and Development Plan (Nos. 2016YFC03007042017YFC030660)。
文摘The hadal zone(ocean depths of 6 – 11 km) is one of the least-understood habitats on Earth because of its extreme conditions such as high pressure, darkness, and low temperature. With the development of deep-sea vehicles such as China's 7000 m manned submersible Jiaolong, abyssal science has received greater attention. For decades, gravity-piston corers have been widely used to collect loose subsea-sediment long-core samples. However, the weight and length of the gravity sampler cables and the operating environment limit sampling capacity at full ocean depths. Therefore, a new self-floating sediment sampler with a spring-loaded auto-trigger release and that incorporates characteristics from traditional gravity-driven samplers is designed. This study analyzes the process by which a gravity-piston corer penetrates the sediment and the factors that affect it. A formula for obtaining the penetration depth is deduced. A method of optimizing the sampling depth is then developed based on structure design and parametric factor modeling. The parameters considered in the modeling include the sampling depth, balance weight, ultimate stress friction coefficient, dimensions of the sampler, and material properties. Thus, a new deep-sea floating parametric sampler designed based on virtual prototyping is proposed. Accurate values for all the design factors are derived from calculations based on the conservation of energy with penetration depth, analyses of the factors affecting the penetration depth, and analyses of the pressure bar stability. Finally, experimental data are used to verify the penetration-depth function and to provide theoretical guidance for the design of sediment samplers.
基金supported by National Hi-tech Research and Development Program of China(863 Program,Grant Nos. 2006AA09A204-1,2006AA09Z222-1,2009AA09A20401-1)
文摘The issues of how to quickly collect seawater samples and of how to make sure that those samples truly reflect the in-situ information on gas composition and concentration have therefore become a hot but difficult topic in the field of ocean technology.Most conventional seawater samplers only focus on collecting seawater itself,but take little consideration on gas preservation.A set of new oceanographic tools are presented for ocean resource exploration such as hydrothermal sulfide and gas hydrate,and for investigations on the processes and mechanisms of marine physical,chemical and biological evolutions.A gas-tight deep-sea water sampling system（GTWSS） is designed for the collection of deep-sea geochemical samples.This set of tools mainly consists of a conductivity temperature depth profiler（CTD）,release devices and gas-tight deep-sea water samplers（GTWS）.The GTWS is able to hold the gases in deep-sea water samples tightly,providing in-situ information on gas contents in the seawater samples and can be deployed on a routine wire-deployed CTD sampler for multi-layer discrete sampling of gas-tight seawater.Sea trials are performed successfully in 2008 and 2009,on a research vessel named HaiYang Si Hao in South China Sea,with the deepest trial depth 3 930 m.GTWSS is capable of quickly sampling 12 discrete gas-tight seawater samples（8.3 L per sample） during its single deployment.The head space method is employed to separate the gases from the seawater samples immediately after recovery of the seawater samples on the vessel.Field geochemical analysis is carried out by gaseous hydrocarbon sensors and an infrared gas analyzer.Results show that the concentrations of CH4 and CO2 in the seawater sampled by GTWSS are higher than those sampled by general non-gas-tight water samplers,thus confirming the gas tightness of GTWSS.Seawater samples can be collected quickly by using GTWSS,and GTWSS can keep the samples＇ integrity quite well.
基金Financial supports from the National Natural Science Foundation of China(No.21476256)Science Foundation of China University of PetroleumBeijing(Nos.2462017BJB03&2462018BJC004)are gratefully acknowledged.
文摘Heat exchanger networks(HENs)in separated plants can be simultaneously synthesized through process streams directly or intermediate fluids indirectly.However,the direct and indirect methods are studied separately in most existing researches.As the result,conventional designs are probably suboptimal,because optimal solutions may call for hybrid approach wherein direct and indirect integration methods are used synchronously.To circumvent this drawback aforementioned,we propose in this research a novel methodology to synthesize multi-plant HENs considering both direct and indirect approaches.The methodology employs a novel superstructure covering most potential topologies for both interplant and intra-plant heat integration.We also take into account multiple kinds of intermediate fluids for indirect integration and this has not been fully addressed in previous research.A mixed-integer nonlinear programming(MINLP)is formulated to optimize multi-plant HENs involving indirect and direct methods.One example from existing literature and one industrial problem are solved to demonstrate the methodology’s capability.
基金Supported by National Key Research and Development Program of China(Grant No.2016YFC0300502)National Natural Science Foundation of China(Grant No.517779092)+1 种基金Special Project for the Construction of Innovative Provinces in Hunan(Grant No.2019GK1012)Postgraduate Scientific Research Innovation Project of Hunan Province(Grant No.CX20210985).
文摘Aiming at the requirement of the full-ocean-depth(operating water depth 11000 m)manned submersible to carry out the gas-tight sampling operation of the abyss seabed sediment,a kind of full-ocean-depth carrier submersible mechanical hand-held,full-ocean-depth gas-tight sediment sampler(GTSS)with the function of pressure-retaining and coring is designed.Firstly,the volume change model of pressure compensator is established,and it is pointed out that the volume of pressure compensator is about 16.14%equal to the volume of gas-tight sediment sampler(GTSS).Secondly,the pressure compensator is analyzed and calculated,and the relationship between the precharge pressure of the pressure compensator,the nominal volume of the pressure compensator and the pressure holding effect of the gas-tight sediment sampler(GTSS)is studied.The results show that with the increase of gas precharge pressure in the pressure compensator,the final pressure of the sampler also increases.Under the same precharge pressure condition,the larger the nominal volume of the pressure compensator,the greater the final pressure of the sampler.Finally,the air tightness test method is designed by using the developed gas tightness sampler of the full-ocean-depth product,and the change of the final pressure in the gas tight sampler under different precharge pressure is observed.The test results are consistent with the simulation results,indicating the correctness of the pressure compensation system(PCS)model.
基金financially supported by the National High Technology Research and Development Program of China(863 Program,Grant No.2010AA09Z202)the National Natural Science Foundation of China(Grant No.41106081)+2 种基金the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(Grant No.51221004)the United States National Science Foundation(Grant No.0927615)the Knowledge Innovation Project from Sanya Institute of Deep-sea Science and Engineering(Grant No.SIDSSE-201204)
文摘This paper describes the design, construction and preliminary test results for a gas-tight serial sampler intended to be deployed at seafloor for long-term operation to take time-series fluid samples from deep-sea environments such as cold seeps, water column and hydrothermal vents. The serial sampler is a modular system that is based on independent and identical sampling modules, which are designed to collect six 160 ml gas-tight fluid samples maintained at high pressure to a depth of 4000 meters. With two working modes, the sampler can be deployed either with seafloor cabled observatory for remote control or as a stand-alone device for autonomous operation. A prototype of the instrument has been constructed and tested on the MARS cabled observatory for two months. The laboratory and field tests proved the success of the design and construction of the serial sampler, and indicated the potential for future ocean sciences.
文摘Since the 1970s, the studies on the geography of enterprise have become increasingly concerned with the spatial evolution of an enterprises in the West developed countries. However, little attention has so far been given to the spatial evolution of an enterprise in China. With China's ongoing economy and political reforms, a number of fundamental changes of enterprise behavior have occurred. These changes have certainly important influences on the evolution of industrial location. Therefore, there is a need for examining the spatial evolution of an enterprise in China. The purpose of the paper is to review the mapjor models of both the growth,and associated spatial evolution of an enterprise, with an illustrative case study of the HeaVy Automobile Enterprise Group of China. The paper is organized by three parts. The first examines the spoilal groWth and location adjustment of multi-plant enterprise. The second reviews mapjor models of the spatial evolution of an enterprise. And the third analyzes the spatial evolution, over a period of time, of a representative sample of the Heavy Automobile Enterprise Group of China, and illustrates the findings with case studies. It is suggested that the models of spatial evolution of an enterprise would provide more evidence about micro-mechanism for evolution of micro- regional economic systems.
