In the context of security systems,adequate signal coverage is paramount for the communication between security personnel and the accurate positioning of personnel.Most studies focus on optimizing base station deploym...In the context of security systems,adequate signal coverage is paramount for the communication between security personnel and the accurate positioning of personnel.Most studies focus on optimizing base station deployment under the assumption of static obstacles,aiming to maximize the perception coverage of wireless RF(Radio Frequency)signals and reduce positioning blind spots.However,in practical security systems,obstacles are subject to change,necessitating the consideration of base station deployment in dynamic environments.Nevertheless,research in this area still needs to be conducted.This paper proposes a Dynamic Indoor Environment Beacon Deployment Algorithm(DIE-BDA)to address this problem.This algorithm considers the dynamic alterations in obstacle locations within the designated area.It determines the requisite number of base stations,the requisite time,and the area’s practical and overall signal coverage rates.The experimental results demonstrate that the algorithm can calculate the deployment strategy in 0.12 s following a change in obstacle positions.Experimental results show that the algorithm in this paper requires 0.12 s to compute the deployment strategy after the positions of obstacles change.With 13 base stations,it achieves an effective coverage rate of 93.5%and an overall coverage rate of 97.75%.The algorithm can rapidly compute a revised deployment strategy in response to changes in obstacle positions within security systems,thereby ensuring the efficacy of signal coverage.展开更多
In indoor environments,various batterypowered Internet of Things(IoT)devices,such as remote controllers and electronic tags on high-level shelves,require efficient energy management.However,manually monitoring remaini...In indoor environments,various batterypowered Internet of Things(IoT)devices,such as remote controllers and electronic tags on high-level shelves,require efficient energy management.However,manually monitoring remaining energy levels and battery replacement is both inadequate and costly.This paper introduces an energy management system for indoor IoT,which includes a mobile energy station(ES)for enabling on-demand wireless energy transfer(WET)in radio frequency(RF),some energy receivers(ERs),and a cloud server.By implementing a two-stage positioning system and embedding energy receivers into traditional IoT devices,we robustly manage their energy storage.The experimental results demonstrate that the energy receiver can harvest a minimum power of 58 mW.展开更多
CHINA.5G Base Stations See Strong Growth.China witnessed substantial growth in the number of 5G base stations in 2025,according to data from the Ministry of Industry and Information Technology.As of the end of October...CHINA.5G Base Stations See Strong Growth.China witnessed substantial growth in the number of 5G base stations in 2025,according to data from the Ministry of Industry and Information Technology.As of the end of October 2025,the total number of 5G base stations in the country reached around 4.76 million,with a net increase of 507,000 from the end of last year,accounting for 37 percent of all mobile base stations.展开更多
This paper proposes an equivalent modeling method for photovoltaic(PV)power stations via a particle swarm optimization(PSO)K-means clustering(KMC)algorithm with passive filter parameter clustering to address the compl...This paper proposes an equivalent modeling method for photovoltaic(PV)power stations via a particle swarm optimization(PSO)K-means clustering(KMC)algorithm with passive filter parameter clustering to address the complexities,simulation time cost and convergence problems of detailed PV power station models.First,the amplitude–frequency curves of different filter parameters are analyzed.Based on the results,a grouping parameter set for characterizing the external filter characteristics is established.These parameters are further defined as clustering parameters.A single PV inverter model is then established as a prerequisite foundation.The proposed equivalent method combines the global search capability of PSO with the rapid convergence of KMC,effectively overcoming the tendency of KMC to become trapped in local optima.This approach enhances both clustering accuracy and numerical stability when determining equivalence for PV inverter units.Using the proposed clustering method,both a detailed PV power station model and an equivalent model are developed and compared.Simulation and hardwarein-loop(HIL)results based on the equivalent model verify that the equivalent method accurately represents the dynamic characteristics of PVpower stations and adapts well to different operating conditions.The proposed equivalent modeling method provides an effective analysis tool for future renewable energy integration research.展开更多
To alleviate the resulting increase in energy consumption and emissions and other issues caused by the traffic congestion ahead of the expressway toll station, a novel traffic flowcontrol method is put forward based o...To alleviate the resulting increase in energy consumption and emissions and other issues caused by the traffic congestion ahead of the expressway toll station, a novel traffic flowcontrol method is put forward based on the environment-friendly conception. The technical thinking of inducing the slowly moving traffic into a batch pass is determined based on the conclusion of the research, traffic flowtheory and traffic sensing detection technology. The model of stop times is established and the parameters of the system are optimized in accordance with the principle of minimizing the fuel consumption. The optimal location selection of traffic control lights and Detector 2 for queue of different lengths at toll stations are calculated based on the model. Finally, the effect of the congestion flowcontrol system is verified via the Paramics simulation system. The result shows that the control system is capable of reducing90% of fuel consumption for vehicles going through toll stations.展开更多
We present the results of two ground-based radio-echo-sounding（RES） and GPS surveys performed in the vicinity of new Chinese Taishan station,Princess Elizabeth Land,East Antarctica,obtained in two austral summers du...We present the results of two ground-based radio-echo-sounding（RES） and GPS surveys performed in the vicinity of new Chinese Taishan station,Princess Elizabeth Land,East Antarctica,obtained in two austral summers during CHINARE 21（2004/2005） and CHINARE 29（2012/2013）.The radar surveys measured ice thickness and internal layers using 60- and 150-MHz radar systems,and GPS measurements showed smooth surface slopes around the station with altitudes of 2607-2636 m above sea level（a.s.l.）.Radar profiles indicate an average ice thickness of 1900 m,with a maximum of 1949 m and a minimum of 1856 m,within a square area measuring approximately 2 km × 2 km in the vicinity of the station.The ice thickness beneath the station site is 1870 m.The subglacial landscape beneath the station is quiet sharp and ranges from 662 to 770 m a.s.l.,revealing part of a mountainous topography.The ice volume in the grid is estimated to be 7.6 km^3.Along a 60-MHz radar profile with a length of 17.6 km at the region covering the station site,some disturbed internal layers are identified and traced;the geometry of internal layers within the englacial stratigraphy may imply a complex depositional process in the area.展开更多
As fundamental parameters of the Antarctic Ice Sheet,ice thickness and subglacial topography are critical factors for studying the basal conditions and mass balance in Antarctica.During CHINARE 24（the 24 th Chinese N...As fundamental parameters of the Antarctic Ice Sheet,ice thickness and subglacial topography are critical factors for studying the basal conditions and mass balance in Antarctica.During CHINARE 24（the 24 th Chinese National Antarctic Research Expedition,2007/08）,the research team used a deep ice-penetrating radar system to measure the ice thickness and subglacial topography of the ＂Chinese Wall＂ around Kunlun Station,East Antarctica.Preliminary results show that the ice thickness varies mostly from 1600 m to 2800 m along the ＂Chinese Wall＂,with the thickest ice being 3444 m,and the thinnest ice 1255 m.The average bedrock elevation is 1722 m,while the minimum is just 604 m.Compared with the northern side of the ice divide,the ice thickness is a little greater and the subglacial topography lower on the southern side,which is also characterized by four deep valleys.We found no basal freeze-on ice in the Gamburtsev Subglacial Mountains area,subglacial lakes,or water bodies along the ＂Chinese Wall＂.Ice thickness and subglacial topography data extracted from the Bedmap 2 database along the ＂Chinese Wall＂ are consistent with our results,but their resolution and accuracy are very limited in areas where the bedrock fluctuates intensely.The distribution of ice thickness and subglacial topography detected by ice-penetrating radar clarifies the features of the ice sheet in this ＂inaccessible＂ region.These results will help to advance the study of ice sheet dynamics and the determination of future locations of the GSM＇s geological and deep ice core drilling sites in the Dome A region.展开更多
In order to study the spatiotemporal characteristics of the dockless bike sharing system(BSS)around urban rail transit stations,new normalized calculation methods are proposed to explore the temporal and spatial usage...In order to study the spatiotemporal characteristics of the dockless bike sharing system(BSS)around urban rail transit stations,new normalized calculation methods are proposed to explore the temporal and spatial usage patterns of the dockless BSS around rail transit stations by using 5-weekday dockless bike sharing trip data in Nanjing,China.First,the rail transit station area(RTSA)is defined by extracting shared bike trips with trip ends falling into the area.Then,the temporal and spatial decomposition methods are developed and two criterions are calculated,namely,normalized dynamic variation of bikes(NDVB)and normalized spatial distribution of trips(NSDT).Furthermore,the temporal and spatial usage patterns are clustered and the corresponding geographical distributions of shared bikes are determined.The results show that four temporal usage patterns and two spatial patterns of dockless BSS are finally identified.Area type(urban center and suburb)has a great influence on temporal usage patterns.Spatial usage patterns are irregular and affected by limited directions,adjacent rail transit stations and street networks.The findings can help form a better understanding of dockless shared bike users behavior around rail transit stations,which will contribute to improving the service and efficiency of both rail transit and BSS.展开更多
The discovery of oil and gas in Uganda has attracted many investors, leading to increase in fuel/gas distributing companies and fueling stations creating rapid demand for land to locate the stations compared to availa...The discovery of oil and gas in Uganda has attracted many investors, leading to increase in fuel/gas distributing companies and fueling stations creating rapid demand for land to locate the stations compared to available open urban land. Because of the explosive and combustion characteristics of fuel stored and dispensed at stations, several studies have been conducted on different fires at fueling stations such as static fire, jet fire, vapor cloud explosions, open fires, etc. but there was need to assess spatially the risk of fire from stations, its consequences and sovereignty on buildings surrounding them. This was done basing on seven parameters—proximity of buildings to stations, building materials, distance between buildings, wind speed, temperature, slope and vegetation. Analytical hierarchy process and pairwise comparison were used to weight the parameters based on their relative importance. Weighted sum tool was applied to generate the fire risk maps for the quarters—December to February, March to May, June to August, and September to November from 2008 to 2013. The parameters were overlaid with the buildings in each risk zone for all the four quarters and their influences determined. The highest contributors were proximity of the buildings to stations, building materials and separation between buildings. Most of the affected buildings were made of rusted corrugated iron sheets and wood;the separation distance from one building to another ranged from 0 - 4 m. Most of buildings located within 100 m from stations were at moderate risk level and within 50 m were at highest risk level. The period of December to February and June to August had the highest risk. The findings can be used to guide planners and policy makers on building location vs. material vs. separation. It can also guide developers on where, when and how to carry out their developments.展开更多
The Jinping I hydropower station is a huge water conservancy project consisting of the highest concrete arch dam to date in the world and a highly complex and large underground powerhouse cavern. It is located on the ...The Jinping I hydropower station is a huge water conservancy project consisting of the highest concrete arch dam to date in the world and a highly complex and large underground powerhouse cavern. It is located on the right bank with extremely high in-situ stress and a few discontinuities observed in surrounding rock masses. The problems of rock mass deformation and failure result in considerable challenges related to project design and construction and have raised a wide range of concerns in the fields of rock mechanics and engineering. During the excavation of underground caverns, high in-situ stress and relatively low rock mass strength in combination with large excavation dimensions lead to large deformation of the surrounding rock mass and support. Existing experiences in excavation and support cannot deal with the large deformation of rock mass effectively, and further studies are needed. In this paper, the geological conditions, layout of caverns, and design of excavation and support are first introduced, and then detailed analyses of deformation and failure characteristics of rocks are presented. Based on this, the mechanisms of deformation and failure are discussed, and the support adjustments for controlling rock large deformation and subsequent excavation procedures are proposed. Finally, the effectiveness of support and excavation adjustments to maintain the stability of the rock mass is verified. The measures for controlling the large deformation of surrounding rocks enrich the practical experiences related to the design and construction of large underground openings, and the construction of caverns in the Jinping I hydropower station provides a good case study of large-scale excavation in highly stressed ground with complex geological structures, as well as a reference case for research on rock mechanics.展开更多
Gas stations are important emissions source of benzene (C6H6), toluene (C7H8), ethylbenzene (C8H10), and ortho, meta and para-xylene (C8H10)—better known by the acronym BTEX. The objective of this study was to determ...Gas stations are important emissions source of benzene (C6H6), toluene (C7H8), ethylbenzene (C8H10), and ortho, meta and para-xylene (C8H10)—better known by the acronym BTEX. The objective of this study was to determine the concentrations of BTEX compounds in the ambient air of ten gas stations in the cities of Salvador and Feira de Santana, Bahia, Brazil and evaluate the health risks to workers. Passive samplers diffusive of the Radiello?, containing activated carbon as adsorbent, were used. The samplers were exposed for 8 h and then the analytes were recovered by chemical desorption with CS2 and determined by GC-FID. The BTEX concentrations found in the ambient air of gas stations ranged from 46.72 - 435.43 μg·m?3 for benzene;25.54 - 342.46 μg·m?3 for toluene, 7.10 - 30.07 μg·m?3 for ethylbenzene, 9.36 - 89.73 μg·m?3 for m, p-xylene and 9.79 - 52.29 μg·m?3 for o-xylene. The concentrations of toluene, ethylbenzene and xylenes found in gas stations were lower than the limits recommended by the US NIOSH and NR-15 of the Ministry of Labour of Brazil;however, it should be considered the risks due to chronic exposure of workers. Benzene concentrations in three gas stations were above the exposure limit recommended by NIOSH (3.20 × 102 μg·m?3). Samplings were also held outdoors at 250 m of two gas stations. The total concentrations of the BTEX compounds were equal to 24.97 and 35.51 μg·m?3, and benzene concentrations were about 3 - 4 times higher than the annual pattern of 5.0 μg·m?3 established by Union European, as tolerance limit for outside areas. These data confirm that the next areas of gas stations are subject to the effects of volatilization of these compounds. Additionally, the values found in the 10 gas stations for the cancer risk ranged from 4.06 × 10?5 - 3.78 × 10?4 (mean of 1.82 × 10?4) for workers exposed to benzene for 30 years (acceptable limit equal 1.00 × 10?6). The cancer risk is very high, because the values found are about 40 - 378 times above the acceptable limit and reinforce the need to adopt urgent measures to reduce or eliminate exposure of workers to the BTEX compounds. The average non-cancer risk to benzene, toluene, ethylbenzene and xylenes was 1.84, 5.76 × 10?3, 4.59 × 10?3 and 1.37 × 10?1, respectively (acceptable limit 1). Only to benzene the average value of this risk is above 1, showing that workers are likely the adverse effects health due to exposure to benzene.展开更多
China has planned and implemented a series of lunar and deep space exploration programs since the first lunar exploration satellite Chang’E-1 launched in 2007.In the future,China has initiated the international lunar...China has planned and implemented a series of lunar and deep space exploration programs since the first lunar exploration satellite Chang’E-1 launched in 2007.In the future,China has initiated the international lunar research station program,which aims to build a shared platform on the Moon jointly with many other countries for long-term and continuous lunar exploration,lunar-based observations and experiments,as well as in-situ resource utilization.In addition,China has also proposed an interstellar express mission to unveil the mysteries of the outer heliosphere,nearby interstellar space,and their interactions.This paper gives a brief introduction to the International Lunar Research Station program and the Interstellar Express mission.展开更多
China scheduled to complete the assembly of the T-shaped Tiangong Space Station in 2022,and will enter a new stage of utilization.There are more than 20 experiment racks inside the modules,and more than 50 external on...China scheduled to complete the assembly of the T-shaped Tiangong Space Station in 2022,and will enter a new stage of utilization.There are more than 20 experiment racks inside the modules,and more than 50 external onboard payloads mounting spaces,which will support large-scale science and technology experiments during the operation.The development of internal experiment racks and external research accommodations approved during the construction has been completed,of which 4 racks in Tianhe core module,including High Microgravity Level research Rack(HMLR)and Container-less Materials Processing Rack(CMPR),have finished on-orbit tests;while other racks in Wentian and Mengtian experiment modules are under comprehensive ground tests.The Chinese Space Survey Telescope(CSST)has advanced much in the last two years with 24 pre-launch research projects funded and 4 joint science center built in preparation for CSST’s future scientific observations and operations.The systematic research planning for China’s Space Station(CSS)during 2022-2032 is updated with the researches classified into four important areas:space life sciences and human research,microgravity physical sciences,space astronomy and Earth science,and new space technologies and applications.According to the planning,more than 1000 experiments are expected to perform in CSS during the operating period.Overall,the CSS utilization missions are proceeding as planned,which will contribute to the major scientific or application output and have a positive impact on the quality of life on Earth.展开更多
The present paper aims at modeling suspended sediment load(SSL) using heuristic data driven methodologies, e.g. Gene Expression Programming(GEP) and Support Vector Machine(SVM) in three successive hydrometric stations...The present paper aims at modeling suspended sediment load(SSL) using heuristic data driven methodologies, e.g. Gene Expression Programming(GEP) and Support Vector Machine(SVM) in three successive hydrometric stations of Housatonic River in U.S. The simulations were carried out through local and cross-station data management scenarios to investigate the interrelations between the SSL values of upstream/downstream stations. The available scenarios were applied to predict SSL values using GEP to obtain the best models. Then, the best models were predicted by SVM approach and the obtained results were compared with those of GEP. The comparison of the results revealed that the SVM technique is more capable than the GEP for modeling the SSL through the both local and cross-station data management strategies. Besides, local application seems to be better than cross-station application for modeling SSL. Nevertheless, the cross-station application demonstrated to be a valid methodology for simulating SSL, which would be of interest for the stations with lack of observational data. Also, the prediction capability of conventional Sediment Rating Curve(SRC) method was compared with those of GEPand SVM techniques. The obtained results revealed the superiority of GEP and SVM-based models over the traditional SRC technique in the studied stations.展开更多
It has been revealed that prolonged shelter life caused by Fukushima Daiichi Nuclear Power Station accident in conjunction with the Great East Japan Earthquake influences sleep and mental health of the residents, and ...It has been revealed that prolonged shelter life caused by Fukushima Daiichi Nuclear Power Station accident in conjunction with the Great East Japan Earthquake influences sleep and mental health of the residents, and therefore its influence on their physical and emotional health has become a concern. Therefore, in this study, the authors aimed at clarifying actual situations of sleep and stress of middle age males living in shelters for a long period in each of emergency temporary houses and post-earthquake public houses. For 5 males who moved from emergency temporary houses to post-earthquake public houses, their objective and subjective sleep states were measured with Actigraph and PSQI, respectively. Furthermore, their objective and subjective stresses were measured with saliva stress biomarkers and GHQ28, respectively. Their data were analyzed by paired t-test. As result, in comparison between the life in the emergency temporary houses and post-earthquake public houses, significant variation was not recognized in their objective sleep states and saliva stress biomarkers though their subjective sleep and subjective stress were significantly worsened after moving to the post-earthquake public houses.展开更多
The optimization of network performance in a movement-assisted data gathering scheme was studied by analyzing the energy consumption of wireless sensor network with node uniform distribution. A theoretically analytica...The optimization of network performance in a movement-assisted data gathering scheme was studied by analyzing the energy consumption of wireless sensor network with node uniform distribution. A theoretically analytical method for avoiding energy hole was proposed. It is proved that if the densities of sensor nodes working at the same time are alternate between dormancy and work with non-uniform node distribution. The efficiency of network can increase by several times and the residual energy of network is nearly zero when the network lifetime ends.展开更多
Chinese Space Station(CSS)has been fully deployed by the end of 2022,and the facility has entered into the application and development phase.It has conducted scientific research projects in various fields,such as spac...Chinese Space Station(CSS)has been fully deployed by the end of 2022,and the facility has entered into the application and development phase.It has conducted scientific research projects in various fields,such as space life science and biotechnology,space materials science,microgravity fundamental physics,fluid physics,combustion science,space new technologies,and applications.In this review,we introduce the progress of CSS development and provide an overview of the research conducted in Chinese Space Station and the recent scientific findings in several typical research fields.Such compelling findings mainly concern the rapid solidification of ultra-high temperature alloy melts,dynamics of fluid transport in space,gravity scaling law of boiling heat transfer,vibration fluidization phenomenon of particulate matter,cold atom interferometer technology under high microgravity and related equivalence principle testing,the full life cycle of rice under microgravity and so forth.Furthermore,the planned scientific research and corresponding prospects of Chinese space station in the next few years are presented.展开更多
This study assessed the impact of petrol service stations on physico-chemical water quality in Port Harcourt metropolis, Rivers State. This threw light on the extent of damage and alteration of water quality in Port H...This study assessed the impact of petrol service stations on physico-chemical water quality in Port Harcourt metropolis, Rivers State. This threw light on the extent of damage and alteration of water quality in Port Harcourt metropolis as a result of the proliferation of petrol service stations especially the condition of ground and nearby surface water. This serves as a useful tool to government and regulatory authorities for planning especially due to lack of central water supply system in Port Harcourt metropolis. The parameters studied were sampled, measured and analyzed using in situ and other standard methods. Remarkable results above permissible limits of interest for physicochemical parameter analysis revealed pH values from 4.6 to 6.8, electrical conductivity from 0.002 µS/cm to 0.42 µS/cm, salinity from 3 ppm to 4050 ppm, and temperatures from 19.9˚C to 32.6˚C. Total dissolved solids (TDS) varied from 7 ppm to 1000 ppm, biochemical oxygen demand (BOD) from 0.167 mg/L to 2.167 mg/L, chemical oxygen demand (COD) from 0.257 mg/L to 3.253 mg/L, and dissolved oxygen (DO) concentrations from 1.70 mg/L to 4.30 mg/L. Specifically, water samples from NNPC Filling Station (Choba) and Eneka Pond displayed “Poor” water quality with WQI values of 112.003 and 112.076, respectively. Similarly, ALLTEC Filling Station (Eneka) and TOTAL Filling Station (Rumuomasi) had “Poor” water quality with WQI values of 173.707 and 180.946, respectively. In contrast, Excelsis Filling Station (Akpajo) demonstrated “Good” water quality with a WQI of 85.2072, while Total Filling Stations (Slaughter) and Choba River revealed “unsuitable for drinking” water quality with WQI values of 552.461 and 654.601, respectively. Slaughter River also indicated very poor water quality with a WQI of 442.024. The physicochemical and nutrient analyses of the water samples showed that activities of the filling stations within the study area may have polluted groundwater in the environment posing poor aesthetics and great health risk to consumers of the water bodies. The findings underscore the need for immediate remediation efforts and stricter regulatory measures to protect water quality. The study concluded that surface and groundwater near petrol service stations in Port Harcourt are unfit for drinking and irrigation purposes without adequate treatment.展开更多
文摘In the context of security systems,adequate signal coverage is paramount for the communication between security personnel and the accurate positioning of personnel.Most studies focus on optimizing base station deployment under the assumption of static obstacles,aiming to maximize the perception coverage of wireless RF(Radio Frequency)signals and reduce positioning blind spots.However,in practical security systems,obstacles are subject to change,necessitating the consideration of base station deployment in dynamic environments.Nevertheless,research in this area still needs to be conducted.This paper proposes a Dynamic Indoor Environment Beacon Deployment Algorithm(DIE-BDA)to address this problem.This algorithm considers the dynamic alterations in obstacle locations within the designated area.It determines the requisite number of base stations,the requisite time,and the area’s practical and overall signal coverage rates.The experimental results demonstrate that the algorithm can calculate the deployment strategy in 0.12 s following a change in obstacle positions.Experimental results show that the algorithm in this paper requires 0.12 s to compute the deployment strategy after the positions of obstacles change.With 13 base stations,it achieves an effective coverage rate of 93.5%and an overall coverage rate of 97.75%.The algorithm can rapidly compute a revised deployment strategy in response to changes in obstacle positions within security systems,thereby ensuring the efficacy of signal coverage.
基金supported in part by the Natural Science Foundation of China(NSFC)under Grant 61971102in part by the Key Research and Development Program of Zhejiang Province under Grant 2022C01093.
文摘In indoor environments,various batterypowered Internet of Things(IoT)devices,such as remote controllers and electronic tags on high-level shelves,require efficient energy management.However,manually monitoring remaining energy levels and battery replacement is both inadequate and costly.This paper introduces an energy management system for indoor IoT,which includes a mobile energy station(ES)for enabling on-demand wireless energy transfer(WET)in radio frequency(RF),some energy receivers(ERs),and a cloud server.By implementing a two-stage positioning system and embedding energy receivers into traditional IoT devices,we robustly manage their energy storage.The experimental results demonstrate that the energy receiver can harvest a minimum power of 58 mW.
文摘CHINA.5G Base Stations See Strong Growth.China witnessed substantial growth in the number of 5G base stations in 2025,according to data from the Ministry of Industry and Information Technology.As of the end of October 2025,the total number of 5G base stations in the country reached around 4.76 million,with a net increase of 507,000 from the end of last year,accounting for 37 percent of all mobile base stations.
基金supported by the Research Project of China Southern Power Grid(No.056200KK52222031).
文摘This paper proposes an equivalent modeling method for photovoltaic(PV)power stations via a particle swarm optimization(PSO)K-means clustering(KMC)algorithm with passive filter parameter clustering to address the complexities,simulation time cost and convergence problems of detailed PV power station models.First,the amplitude–frequency curves of different filter parameters are analyzed.Based on the results,a grouping parameter set for characterizing the external filter characteristics is established.These parameters are further defined as clustering parameters.A single PV inverter model is then established as a prerequisite foundation.The proposed equivalent method combines the global search capability of PSO with the rapid convergence of KMC,effectively overcoming the tendency of KMC to become trapped in local optima.This approach enhances both clustering accuracy and numerical stability when determining equivalence for PV inverter units.Using the proposed clustering method,both a detailed PV power station model and an equivalent model are developed and compared.Simulation and hardwarein-loop(HIL)results based on the equivalent model verify that the equivalent method accurately represents the dynamic characteristics of PVpower stations and adapts well to different operating conditions.The proposed equivalent modeling method provides an effective analysis tool for future renewable energy integration research.
基金The Natural Science Foundation of Hebei Province(No.E2013202228)the Science and Technology Planning Project of the Department of Transportation of Hebei Province(No.R070245)
文摘To alleviate the resulting increase in energy consumption and emissions and other issues caused by the traffic congestion ahead of the expressway toll station, a novel traffic flowcontrol method is put forward based on the environment-friendly conception. The technical thinking of inducing the slowly moving traffic into a batch pass is determined based on the conclusion of the research, traffic flowtheory and traffic sensing detection technology. The model of stop times is established and the parameters of the system are optimized in accordance with the principle of minimizing the fuel consumption. The optimal location selection of traffic control lights and Detector 2 for queue of different lengths at toll stations are calculated based on the model. Finally, the effect of the congestion flowcontrol system is verified via the Paramics simulation system. The result shows that the control system is capable of reducing90% of fuel consumption for vehicles going through toll stations.
基金financially supported by the National Natural Science Foundation of China(Grant No.41376192,40906101)the National Basic Research Program of China(973 Program)(Grant No.2013CBA01804 and 2012CB957702)+2 种基金the Foreign Cooperation Support Program of Chinese Arctic and Antarctic Administration,SOA,China(Grand No.IC201214)the Natural Science Foundation of Shanghai,China(Grand No.13ZR1445300)the Chinese Polar Environment Comprehensive Investigation&Assessment Programmes(CHINARE2014-01-01)
文摘We present the results of two ground-based radio-echo-sounding（RES） and GPS surveys performed in the vicinity of new Chinese Taishan station,Princess Elizabeth Land,East Antarctica,obtained in two austral summers during CHINARE 21（2004/2005） and CHINARE 29（2012/2013）.The radar surveys measured ice thickness and internal layers using 60- and 150-MHz radar systems,and GPS measurements showed smooth surface slopes around the station with altitudes of 2607-2636 m above sea level（a.s.l.）.Radar profiles indicate an average ice thickness of 1900 m,with a maximum of 1949 m and a minimum of 1856 m,within a square area measuring approximately 2 km × 2 km in the vicinity of the station.The ice thickness beneath the station site is 1870 m.The subglacial landscape beneath the station is quiet sharp and ranges from 662 to 770 m a.s.l.,revealing part of a mountainous topography.The ice volume in the grid is estimated to be 7.6 km^3.Along a 60-MHz radar profile with a length of 17.6 km at the region covering the station site,some disturbed internal layers are identified and traced;the geometry of internal layers within the englacial stratigraphy may imply a complex depositional process in the area.
基金supported by National Basic Research Program of China(Grant Nos.2013CBA01804 and 2012CB957702)the Chinese Polar Environmental Comprehensive Investigation and Assessment Programs(Grant No.CHINARE-02-02)the National Science Foundation of China(Grant No.41101071)
文摘As fundamental parameters of the Antarctic Ice Sheet,ice thickness and subglacial topography are critical factors for studying the basal conditions and mass balance in Antarctica.During CHINARE 24（the 24 th Chinese National Antarctic Research Expedition,2007/08）,the research team used a deep ice-penetrating radar system to measure the ice thickness and subglacial topography of the ＂Chinese Wall＂ around Kunlun Station,East Antarctica.Preliminary results show that the ice thickness varies mostly from 1600 m to 2800 m along the ＂Chinese Wall＂,with the thickest ice being 3444 m,and the thinnest ice 1255 m.The average bedrock elevation is 1722 m,while the minimum is just 604 m.Compared with the northern side of the ice divide,the ice thickness is a little greater and the subglacial topography lower on the southern side,which is also characterized by four deep valleys.We found no basal freeze-on ice in the Gamburtsev Subglacial Mountains area,subglacial lakes,or water bodies along the ＂Chinese Wall＂.Ice thickness and subglacial topography data extracted from the Bedmap 2 database along the ＂Chinese Wall＂ are consistent with our results,but their resolution and accuracy are very limited in areas where the bedrock fluctuates intensely.The distribution of ice thickness and subglacial topography detected by ice-penetrating radar clarifies the features of the ice sheet in this ＂inaccessible＂ region.These results will help to advance the study of ice sheet dynamics and the determination of future locations of the GSM＇s geological and deep ice core drilling sites in the Dome A region.
基金The National Key R&D Program of China(No.2018YFB1600900)the Project of International Cooperation and Exchange of the National Natural Science Foundation of China(No.51561135003)the Key Project of National Natural Science Foundation of China(No.51338003)
文摘In order to study the spatiotemporal characteristics of the dockless bike sharing system(BSS)around urban rail transit stations,new normalized calculation methods are proposed to explore the temporal and spatial usage patterns of the dockless BSS around rail transit stations by using 5-weekday dockless bike sharing trip data in Nanjing,China.First,the rail transit station area(RTSA)is defined by extracting shared bike trips with trip ends falling into the area.Then,the temporal and spatial decomposition methods are developed and two criterions are calculated,namely,normalized dynamic variation of bikes(NDVB)and normalized spatial distribution of trips(NSDT).Furthermore,the temporal and spatial usage patterns are clustered and the corresponding geographical distributions of shared bikes are determined.The results show that four temporal usage patterns and two spatial patterns of dockless BSS are finally identified.Area type(urban center and suburb)has a great influence on temporal usage patterns.Spatial usage patterns are irregular and affected by limited directions,adjacent rail transit stations and street networks.The findings can help form a better understanding of dockless shared bike users behavior around rail transit stations,which will contribute to improving the service and efficiency of both rail transit and BSS.
文摘The discovery of oil and gas in Uganda has attracted many investors, leading to increase in fuel/gas distributing companies and fueling stations creating rapid demand for land to locate the stations compared to available open urban land. Because of the explosive and combustion characteristics of fuel stored and dispensed at stations, several studies have been conducted on different fires at fueling stations such as static fire, jet fire, vapor cloud explosions, open fires, etc. but there was need to assess spatially the risk of fire from stations, its consequences and sovereignty on buildings surrounding them. This was done basing on seven parameters—proximity of buildings to stations, building materials, distance between buildings, wind speed, temperature, slope and vegetation. Analytical hierarchy process and pairwise comparison were used to weight the parameters based on their relative importance. Weighted sum tool was applied to generate the fire risk maps for the quarters—December to February, March to May, June to August, and September to November from 2008 to 2013. The parameters were overlaid with the buildings in each risk zone for all the four quarters and their influences determined. The highest contributors were proximity of the buildings to stations, building materials and separation between buildings. Most of the affected buildings were made of rusted corrugated iron sheets and wood;the separation distance from one building to another ranged from 0 - 4 m. Most of buildings located within 100 m from stations were at moderate risk level and within 50 m were at highest risk level. The period of December to February and June to August had the highest risk. The findings can be used to guide planners and policy makers on building location vs. material vs. separation. It can also guide developers on where, when and how to carry out their developments.
文摘The Jinping I hydropower station is a huge water conservancy project consisting of the highest concrete arch dam to date in the world and a highly complex and large underground powerhouse cavern. It is located on the right bank with extremely high in-situ stress and a few discontinuities observed in surrounding rock masses. The problems of rock mass deformation and failure result in considerable challenges related to project design and construction and have raised a wide range of concerns in the fields of rock mechanics and engineering. During the excavation of underground caverns, high in-situ stress and relatively low rock mass strength in combination with large excavation dimensions lead to large deformation of the surrounding rock mass and support. Existing experiences in excavation and support cannot deal with the large deformation of rock mass effectively, and further studies are needed. In this paper, the geological conditions, layout of caverns, and design of excavation and support are first introduced, and then detailed analyses of deformation and failure characteristics of rocks are presented. Based on this, the mechanisms of deformation and failure are discussed, and the support adjustments for controlling rock large deformation and subsequent excavation procedures are proposed. Finally, the effectiveness of support and excavation adjustments to maintain the stability of the rock mass is verified. The measures for controlling the large deformation of surrounding rocks enrich the practical experiences related to the design and construction of large underground openings, and the construction of caverns in the Jinping I hydropower station provides a good case study of large-scale excavation in highly stressed ground with complex geological structures, as well as a reference case for research on rock mechanics.
文摘Gas stations are important emissions source of benzene (C6H6), toluene (C7H8), ethylbenzene (C8H10), and ortho, meta and para-xylene (C8H10)—better known by the acronym BTEX. The objective of this study was to determine the concentrations of BTEX compounds in the ambient air of ten gas stations in the cities of Salvador and Feira de Santana, Bahia, Brazil and evaluate the health risks to workers. Passive samplers diffusive of the Radiello?, containing activated carbon as adsorbent, were used. The samplers were exposed for 8 h and then the analytes were recovered by chemical desorption with CS2 and determined by GC-FID. The BTEX concentrations found in the ambient air of gas stations ranged from 46.72 - 435.43 μg·m?3 for benzene;25.54 - 342.46 μg·m?3 for toluene, 7.10 - 30.07 μg·m?3 for ethylbenzene, 9.36 - 89.73 μg·m?3 for m, p-xylene and 9.79 - 52.29 μg·m?3 for o-xylene. The concentrations of toluene, ethylbenzene and xylenes found in gas stations were lower than the limits recommended by the US NIOSH and NR-15 of the Ministry of Labour of Brazil;however, it should be considered the risks due to chronic exposure of workers. Benzene concentrations in three gas stations were above the exposure limit recommended by NIOSH (3.20 × 102 μg·m?3). Samplings were also held outdoors at 250 m of two gas stations. The total concentrations of the BTEX compounds were equal to 24.97 and 35.51 μg·m?3, and benzene concentrations were about 3 - 4 times higher than the annual pattern of 5.0 μg·m?3 established by Union European, as tolerance limit for outside areas. These data confirm that the next areas of gas stations are subject to the effects of volatilization of these compounds. Additionally, the values found in the 10 gas stations for the cancer risk ranged from 4.06 × 10?5 - 3.78 × 10?4 (mean of 1.82 × 10?4) for workers exposed to benzene for 30 years (acceptable limit equal 1.00 × 10?6). The cancer risk is very high, because the values found are about 40 - 378 times above the acceptable limit and reinforce the need to adopt urgent measures to reduce or eliminate exposure of workers to the BTEX compounds. The average non-cancer risk to benzene, toluene, ethylbenzene and xylenes was 1.84, 5.76 × 10?3, 4.59 × 10?3 and 1.37 × 10?1, respectively (acceptable limit 1). Only to benzene the average value of this risk is above 1, showing that workers are likely the adverse effects health due to exposure to benzene.
基金Supported by National Key Research and Development Program of China(2020YFE0202100)。
文摘China has planned and implemented a series of lunar and deep space exploration programs since the first lunar exploration satellite Chang’E-1 launched in 2007.In the future,China has initiated the international lunar research station program,which aims to build a shared platform on the Moon jointly with many other countries for long-term and continuous lunar exploration,lunar-based observations and experiments,as well as in-situ resource utilization.In addition,China has also proposed an interstellar express mission to unveil the mysteries of the outer heliosphere,nearby interstellar space,and their interactions.This paper gives a brief introduction to the International Lunar Research Station program and the Interstellar Express mission.
文摘China scheduled to complete the assembly of the T-shaped Tiangong Space Station in 2022,and will enter a new stage of utilization.There are more than 20 experiment racks inside the modules,and more than 50 external onboard payloads mounting spaces,which will support large-scale science and technology experiments during the operation.The development of internal experiment racks and external research accommodations approved during the construction has been completed,of which 4 racks in Tianhe core module,including High Microgravity Level research Rack(HMLR)and Container-less Materials Processing Rack(CMPR),have finished on-orbit tests;while other racks in Wentian and Mengtian experiment modules are under comprehensive ground tests.The Chinese Space Survey Telescope(CSST)has advanced much in the last two years with 24 pre-launch research projects funded and 4 joint science center built in preparation for CSST’s future scientific observations and operations.The systematic research planning for China’s Space Station(CSS)during 2022-2032 is updated with the researches classified into four important areas:space life sciences and human research,microgravity physical sciences,space astronomy and Earth science,and new space technologies and applications.According to the planning,more than 1000 experiments are expected to perform in CSS during the operating period.Overall,the CSS utilization missions are proceeding as planned,which will contribute to the major scientific or application output and have a positive impact on the quality of life on Earth.
文摘The present paper aims at modeling suspended sediment load(SSL) using heuristic data driven methodologies, e.g. Gene Expression Programming(GEP) and Support Vector Machine(SVM) in three successive hydrometric stations of Housatonic River in U.S. The simulations were carried out through local and cross-station data management scenarios to investigate the interrelations between the SSL values of upstream/downstream stations. The available scenarios were applied to predict SSL values using GEP to obtain the best models. Then, the best models were predicted by SVM approach and the obtained results were compared with those of GEP. The comparison of the results revealed that the SVM technique is more capable than the GEP for modeling the SSL through the both local and cross-station data management strategies. Besides, local application seems to be better than cross-station application for modeling SSL. Nevertheless, the cross-station application demonstrated to be a valid methodology for simulating SSL, which would be of interest for the stations with lack of observational data. Also, the prediction capability of conventional Sediment Rating Curve(SRC) method was compared with those of GEPand SVM techniques. The obtained results revealed the superiority of GEP and SVM-based models over the traditional SRC technique in the studied stations.
文摘It has been revealed that prolonged shelter life caused by Fukushima Daiichi Nuclear Power Station accident in conjunction with the Great East Japan Earthquake influences sleep and mental health of the residents, and therefore its influence on their physical and emotional health has become a concern. Therefore, in this study, the authors aimed at clarifying actual situations of sleep and stress of middle age males living in shelters for a long period in each of emergency temporary houses and post-earthquake public houses. For 5 males who moved from emergency temporary houses to post-earthquake public houses, their objective and subjective sleep states were measured with Actigraph and PSQI, respectively. Furthermore, their objective and subjective stresses were measured with saliva stress biomarkers and GHQ28, respectively. Their data were analyzed by paired t-test. As result, in comparison between the life in the emergency temporary houses and post-earthquake public houses, significant variation was not recognized in their objective sleep states and saliva stress biomarkers though their subjective sleep and subjective stress were significantly worsened after moving to the post-earthquake public houses.
基金Project(60873081)supported by the National Natural Science Foundation of ChinaProject(NCET-10-0787)supported by Program for New Century Excellent Talents in UniversityProject(11JJ1012)supported by the Natural Science Foundation of Hunan Province,China
文摘The optimization of network performance in a movement-assisted data gathering scheme was studied by analyzing the energy consumption of wireless sensor network with node uniform distribution. A theoretically analytical method for avoiding energy hole was proposed. It is proved that if the densities of sensor nodes working at the same time are alternate between dormancy and work with non-uniform node distribution. The efficiency of network can increase by several times and the residual energy of network is nearly zero when the network lifetime ends.
文摘Chinese Space Station(CSS)has been fully deployed by the end of 2022,and the facility has entered into the application and development phase.It has conducted scientific research projects in various fields,such as space life science and biotechnology,space materials science,microgravity fundamental physics,fluid physics,combustion science,space new technologies,and applications.In this review,we introduce the progress of CSS development and provide an overview of the research conducted in Chinese Space Station and the recent scientific findings in several typical research fields.Such compelling findings mainly concern the rapid solidification of ultra-high temperature alloy melts,dynamics of fluid transport in space,gravity scaling law of boiling heat transfer,vibration fluidization phenomenon of particulate matter,cold atom interferometer technology under high microgravity and related equivalence principle testing,the full life cycle of rice under microgravity and so forth.Furthermore,the planned scientific research and corresponding prospects of Chinese space station in the next few years are presented.
文摘This study assessed the impact of petrol service stations on physico-chemical water quality in Port Harcourt metropolis, Rivers State. This threw light on the extent of damage and alteration of water quality in Port Harcourt metropolis as a result of the proliferation of petrol service stations especially the condition of ground and nearby surface water. This serves as a useful tool to government and regulatory authorities for planning especially due to lack of central water supply system in Port Harcourt metropolis. The parameters studied were sampled, measured and analyzed using in situ and other standard methods. Remarkable results above permissible limits of interest for physicochemical parameter analysis revealed pH values from 4.6 to 6.8, electrical conductivity from 0.002 µS/cm to 0.42 µS/cm, salinity from 3 ppm to 4050 ppm, and temperatures from 19.9˚C to 32.6˚C. Total dissolved solids (TDS) varied from 7 ppm to 1000 ppm, biochemical oxygen demand (BOD) from 0.167 mg/L to 2.167 mg/L, chemical oxygen demand (COD) from 0.257 mg/L to 3.253 mg/L, and dissolved oxygen (DO) concentrations from 1.70 mg/L to 4.30 mg/L. Specifically, water samples from NNPC Filling Station (Choba) and Eneka Pond displayed “Poor” water quality with WQI values of 112.003 and 112.076, respectively. Similarly, ALLTEC Filling Station (Eneka) and TOTAL Filling Station (Rumuomasi) had “Poor” water quality with WQI values of 173.707 and 180.946, respectively. In contrast, Excelsis Filling Station (Akpajo) demonstrated “Good” water quality with a WQI of 85.2072, while Total Filling Stations (Slaughter) and Choba River revealed “unsuitable for drinking” water quality with WQI values of 552.461 and 654.601, respectively. Slaughter River also indicated very poor water quality with a WQI of 442.024. The physicochemical and nutrient analyses of the water samples showed that activities of the filling stations within the study area may have polluted groundwater in the environment posing poor aesthetics and great health risk to consumers of the water bodies. The findings underscore the need for immediate remediation efforts and stricter regulatory measures to protect water quality. The study concluded that surface and groundwater near petrol service stations in Port Harcourt are unfit for drinking and irrigation purposes without adequate treatment.
