Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying availabl...Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying available cold wind in cold regions.This is achieved by a static heat transfer device called thermosyphon equipped with an air insulation layer.A refrigeration unit can be optionally integrated to meet additional cooling requirements.The introduction of air insulation isolates the thermosyphon from ground zones where freezing is not needed,resulting in:(1)steering the cooling resources(cold wind or refrigeration)towards zones of interest;and(2)minimizing refrigeration load.This design is demonstrated using well-validated mathematical models from our previous work based on two-phase enthalpy method of the ground coupled with a thermal resistance network for the thermosyphon.Two Canadian mines are considered:the Cigar Lake Mine and the Giant Mine.The results show that our proposed design can speed the freezing time by 30%at the Giant Mine and by two months at the Cigar Lake Mine.Further,a cooling load of 2.4 GWh can be saved at the Cigar Lake Mine.Overall,this study provides mining practitioners with sustainable solutions of underground AGF.展开更多
Abrupt temperature volatility has detrimental effects on daily activities,macroeconomic growth,and human health.Predicting abrupt temperature volatility and thus diminishing its negative impacts can be achieved by exp...Abrupt temperature volatility has detrimental effects on daily activities,macroeconomic growth,and human health.Predicting abrupt temperature volatility and thus diminishing its negative impacts can be achieved by exploring homogeneous regions of temperature volatility and analyzing the driving factors.To investigate the regionalization of temperature volatility in China's mainland,a network constructed by the cosine similarity of temperature volatility series from China's mainland was embedded in hyperbolic space.Subsequently,we partitioned the network on the hyperbolic map using the critical gap method and then found eight regions in all.Ultimately,a network of communities was constructed while the interaction among communities was quantified.This yields a perspective of temperature volatility regionalization that can accurately reflect factors including altitude,climate type,and the geographic location of mountains.Further analysis demonstrates that the regionalization in the hyperbolic map is distinct from provinces and has a realistic basis:communities in southwest China show strong correlations due to the temperature sensitivity to altitude,and communities in northern China show a convergence in the area of Dingxi,Gansu,mainly owing to the strong temperature sensitivity to climate types.As a consequence,node distributions and community divisions in the hyperbolic map can offer new insights into the regionalization of temperature volatility in China's mainland.The results demonstrate the potential of hyperbolic embedding of complex networks in forecasting future node associations in real-world data.展开更多
Increasing interest has been directed toward the potential of heterogeneous flexible loads to mitigate the challenges associated with the increasing variability and uncertainty of renewable generation.Evaluating the a...Increasing interest has been directed toward the potential of heterogeneous flexible loads to mitigate the challenges associated with the increasing variability and uncertainty of renewable generation.Evaluating the aggregated flexible region of load clusters managed by load aggregators is the crucial basis of power system scheduling for the system operator.This is because the aggregation result affects the qual-ity of the scheduling schemes.A stringent computation based on the Minkowski sum is NP-hard,whereas existing approximation meth-ods that use a special type of polytope exhibit limited adaptability when aggregating heterogeneous loads.This study proposes a stringent internal approximation method based on the convex hull of multiple layers of maximum volume boxes and embeds it into a day-ahead scheduling optimization model.The numerical results indicate that the aggregation accuracy can be improved compared with methods based on one type of special polytope,including boxes,zonotopes,and homothets.Hence,the reliability and economy of the power sys-tem scheduling can be enhanced.展开更多
Using the multi-temporal Landsat data and survey data of national resources, the authors studied the dynamics of cultivated land and landcover changes of typical ecological regions in China. The results of investigati...Using the multi-temporal Landsat data and survey data of national resources, the authors studied the dynamics of cultivated land and landcover changes of typical ecological regions in China. The results of investigation showed that the whole distribution of the cultivated land shifted to Northeast and Northwest China, and as a result, the ecological quality of cultivated land dropped down. The seacoast and cultivated land in the area of Yellow River Mouth expanded by an increasing rate of 0.73 kma-1, with a depositing rate of 2.1 kma-1. The desertification area of the dynamic of Horqin Sandy Land increased from 60.02% of the total land area in1970s to 64.82% in1980s but decreased to 54.90% in early 1990s. As to the change of North Tibet lakes, the water area of the Namu Lake decreased by 38.58 km2 from year 1970 to 1988, with a decreasing rate of 2.14 km2a-1.展开更多
This paper studies pinning-controlled synchronization of complex networks with bounded or unbounded synchronized regions. To study a state-feedback pinning-controlled network with N nodes, it first converts the contro...This paper studies pinning-controlled synchronization of complex networks with bounded or unbounded synchronized regions. To study a state-feedback pinning-controlled network with N nodes, it first converts the controlled network to an extended network of N＋1 nodes without controls. It is shown that the controlled synchronizability of the given network is determined by the real part of the smallest nonzero eigenvalue of the coupling matrix of its extended network when the synchronized region is unbounded; but it is determined by the ratio of the real parts of the largest and the smallest nonzero eigenvalues of the coupling matrix when the synchronized region is bounded. Both theoretical analysis and numerical simulation show that the portion of controlled nodes has no critical values when the synchronized region is unbounded, but it has a critical value when the synchronized region is bounded. In the former case, therefore, it is possible to control the network to achieve synchronization by pinning only one node. In the latter case, the network can achieve controlled synchronization only when the portion of controlled nodes is larger than the critical value.展开更多
A geometric framework is proposed for semiparametric nonlinear regression models based on the concept of least favorable curve, introduced by Severini and Wong (1992). The authors use this framework to drive three kin...A geometric framework is proposed for semiparametric nonlinear regression models based on the concept of least favorable curve, introduced by Severini and Wong (1992). The authors use this framework to drive three kinds of improved approximate confidence regions for the parameter and parameter subset in terms of curvatures. The results obtained by Hamilton et al. (1982), Hamilton (1986) and Wei (1994) are extended to semiparametric nonlinear regression models.展开更多
The object of this article is to introduce new classes of meromorphic functions associated with conic regions. Several properties like the coefficient bounds, growth and distortion theorems, radii of starlikeness and ...The object of this article is to introduce new classes of meromorphic functions associated with conic regions. Several properties like the coefficient bounds, growth and distortion theorems, radii of starlikeness and convexity, partial sums, are investigated. Some consequences of the main results for the well-known classes of meromorphic functions are also pointed out.展开更多
The coal industry in China has been moving from the semiarid eastern to the drier western regions since the beginning of this century.Water protection is of the utmost concern for coal mining in these regions.Lu'a...The coal industry in China has been moving from the semiarid eastern to the drier western regions since the beginning of this century.Water protection is of the utmost concern for coal mining in these regions.Lu'an,as one of the state coal mining bases in China,has been seeing increasingly heavier pressure for the protection of water resources.This article considers Lu'an as an example and describes the ways these concerns may be alleviated.High mine-water utilization rates have effectively reduced wasting of water and,consequently,have reduced water demand.Using the top layers of the Ordavician as aquifuge barriers can prevent floor karst water inrush into the longwall face and can protect the regional Ordovician karst water resources at the same time.The strength of the overlying Quaternary clay can protect against roof collapse and has successfully preserved the Quaternary porous water resource.展开更多
Self-biting disease occurred in most farmed fur animals in the world. The mechanism and rapid detection method of this disease has not been reported. We applied bulked sergeant analysis （BSA） in combination with RAP...Self-biting disease occurred in most farmed fur animals in the world. The mechanism and rapid detection method of this disease has not been reported. We applied bulked sergeant analysis （BSA） in combination with RAPD method to analyze a molecular genetic marker linked with self-biting trait in mink group. The molecular marker was converted into sequence-characterized amplified regions （SCAR） marker for rapid detection of this disease. A single RAPD marker A8 amplified a specific band of 263bp in self-biting minks, which was designated as SRA8-250, and non-specific band of 315bp in both self-biting and healthy minks. The sequences of the bands exhibited 75% and 88% similarity to Canis familiarizes major histocompatibility complex （MHC） class II region and Macaca mulatta MHC class I region, respectively. A SCAR marker SCAR-A8 was designed for the specific fragment SRA8-250 and validated in 30 self-biting minks and 30 healthy minks. Positive amplification of SCAR-A8 was detected in 24 self-biting minks and 12 healthy minks. χ2 test showed significant difference （p〈0.01） in the detection rate between the two groups. This indicated that SRA8-250 can be used as a positive marker to detect self-biting disease in minks. Furthermore, the finding that self-biting disease links with MHC genes has significant implications for the mechanism of the disease.展开更多
Forest ecosystem is one of the most important ecosystems in the world that human-beings rely on. Forest harvesting policy is one of the main criteria indicating how and how much the human beings open up and make use o...Forest ecosystem is one of the most important ecosystems in the world that human-beings rely on. Forest harvesting policy is one of the main criteria indicating how and how much the human beings open up and make use offorest. Whether the policy is reasonable or not has high relations with not only the increasing or decreasing of forest system,but also the development speed of human society. In this paper, the author analyzed the development of interaction between human society and forest ecosystem from ancient times to today. Then author stated that the rational harvesting policy should be the harvesting sequences of both harvesting density and harvesting time, which might result in the maximumcomprehensive benefit, including economical profit, social benefit and ecological benefit, of forest to human society. Atlast, according to the analysis of interaction bctween human-beings and her environment, the prediction analysis for humansociety development in forest regions in the future was prescnted using Entropy Growing Analysis.展开更多
This paper constructs a set of confidence regions of parameters in terms of statistical curvatures for AR(q) nonlinear regression models. The geometric frameworks are proposed for the model. Then several confidence re...This paper constructs a set of confidence regions of parameters in terms of statistical curvatures for AR(q) nonlinear regression models. The geometric frameworks are proposed for the model. Then several confidence regions for parameters and parameter subsets in terms of statistical curvatures are given based on the likelihood ratio statistics and score statistics. Several previous results, such as [1] and [2] are extended to AR(q) nonlinear regression models.展开更多
The weighted Sobolev-Lions type spaces W pl,γ（Ω; E0, E） = W pl,γ（Ω; E） ∩ Lp,γ （Ω; E0） are studied, where E0, E are two Banach spaces and E0 is continuously and densely embedded on E. A new concept of capa...The weighted Sobolev-Lions type spaces W pl,γ（Ω; E0, E） = W pl,γ（Ω; E） ∩ Lp,γ （Ω; E0） are studied, where E0, E are two Banach spaces and E0 is continuously and densely embedded on E. A new concept of capacity of region Ω ∈ Rn in W pl,γ（; E0, E） is introduced. Several conditions in terms of capacity of region Ω and interpolations of E0 and E are found such that ensure the continuity and compactness of embedding operators. In particular, the most regular class of interpolation spaces Eα between E0 and E, depending of α and l, are found such that mixed differential operators Dα are bounded and compact from W pl,γ（Ω; E0, E） to Eα-valued Lp,γ spaces. In applications, the maximal regularity for differential-operator equations with parameters are studied.展开更多
Herein,a novel interference-free surface-enhanced Raman spectroscopy(SERS)strategy based on magnetic nanoparticles(MNPs)and aptamer-driven assemblies was proposed for the ultrasensitive detection of histamine.A core-s...Herein,a novel interference-free surface-enhanced Raman spectroscopy(SERS)strategy based on magnetic nanoparticles(MNPs)and aptamer-driven assemblies was proposed for the ultrasensitive detection of histamine.A core-satellite SERS aptasensor was constructed by combining aptamer-decorated Fe_(3)O_(4)@Au MNPs(as the recognize probe for histamine)and complementary DNA-modified silver nanoparticles carrying 4-mercaptobenzonitrile(4-MBN)(Ag@4-MBN@Ag-c-DNA)as the SERS signal probe for the indirect detection of histamine.Under an applied magnetic field in the absence of histamine,the assembly gave an intense Raman signal at“Raman biological-silent”region due to 4-MBN.In the presence of histamine,the Ag@4-MBN@Ag-c-DNA SERS-tag was released from the Fe_(3)O_(4)@Au MNPs,thus decreasing the SERS signal.Under optimal conditions,an ultra-low limit of detection of 0.65×10^(-3)ng/mL and a linear range 10^(-2)-10^5 ng/mL on the SERS aptasensor were obtained.The histamine content in four food samples were analyzed using the SERS aptasensor,with the results consistent with those determined by high performance liquid chromatography.The present work highlights the merits of indirect strategies for the ultrasensitive and highly selective SERS detection of small biological molecules in complex matrices.展开更多
There are numerous formulae relating to the predictions of sound wave in the cavitating and bubbly flows. However, tile valid regions of those formulae are rather unclear from the view point of physics. In this work, ...There are numerous formulae relating to the predictions of sound wave in the cavitating and bubbly flows. However, tile valid regions of those formulae are rather unclear from the view point of physics. In this work, the validity of the existing formulae is discussed in terms of three regions by employing the analysis of three typical lengths involved （viscous length, thermal diffusion length and bubble radius）. In our discussions, viscosity and thermal diffusion are both considered together with the effects of relative motion between bubbles and liquids. The importance of relative motion and thermal diffusion are quantitatively discussed in a wide range of parameter zones （including bubble radius and acoustic frequency）, The results show that for large bubbles, the effects of relative motion will be prominent in a wide region.展开更多
Up to date information about the existing land cover patterns and changes in land cover over time is one of the prime prerequisites for the preparation of an integrated development plan and economic development progra...Up to date information about the existing land cover patterns and changes in land cover over time is one of the prime prerequisites for the preparation of an integrated development plan and economic development program of a region. By using ETM＋ image data from 2002, we provided a land cover map of deciduous forest regions in Azerbaijan Province, Iran. Initial qualitative evaluation of the data showed no significant radiometric errors. Image classification was carried out using a maximum likelihood-based supervised classification method. In the end, we determined five major land cover classes, i.e., grass lands, deciduous broad-leaf forest, cultivated land, river and land without vegetation cover. Accuracy, estimated by the use of criteria such as overall accuracy from a confusion matrix of classification was 86% with a 0.88 Kappa coefficient. Such high accuracy results demonstrate that the combined use of spectral and textural characteristics increased the number of classes in the field classification, also with excellent accuracy. The availability and use of time series of remote sensing data permit the detection and quantification of land cover changes and improve our understanding of the past and present status of forest ecosystems.展开更多
Based on seismic,drilling,and source rock analysis data,the petroleum geological characteristics and future exploration direction of the oil-rich sags in the Central and West African Rift System(CWARS)are discussed.Th...Based on seismic,drilling,and source rock analysis data,the petroleum geological characteristics and future exploration direction of the oil-rich sags in the Central and West African Rift System(CWARS)are discussed.The study shows that the Central African Rift System mainly develops high-quality lacustrine source rocks in the Lower Cretaceous,and the West African Rift System mainly develops high-quality terrigenous organic matter-rich marine source rocks in the Upper Cretaceous,and the two types of source rocks provide a material basis for the enrichment of oil and gas in the CWARS.Multiple sets of reservoir rocks including fractured basement and three sets of regional cap rocks in the Lower Cretaceous,the Upper Cretaceous,and the Paleogene are developed in the CWARS.Since the Late Mesozoic,due to the geodynamic factors including the dextral strike-slip movement of the Central African Shear Zone,the basins in different directions of the CWARS differ in terms of rifting stages,intervals of regional cap rocks,trap types and accumulation models.The NE-SW trending basins have mainly preserved one stage of rifting in the Early Cretaceous,with regional cap rocks developed in the Lower Cretaceous strata,forming traps of reverse anticlines,flower-shaped structures and basement buried hill,and two types of hydrocarbon accumulation models of"source and reservoir in the same formation,and accumulation inside source rocks"and"up-source and down-reservoir,and accumulation below source rocks".The NW–SE basins are characterized by multiple rifting stages superimposition,with the development of regional cap rocks in the Upper Cretaceous and Paleogene,forming traps of draping anticlines,faulted anticlines,antithetic fault blocks and the accumulation model of"down-source and up-reservoir,and accumulation above source rocks".The combination of reservoir and cap rocks inside source rocks of basins with multiple superimposed rifting stages,as well as the lithologic reservoirs and the shale oil inside source rocks of strong inversion basins are important fields for future exploration in basins of the CWARS.展开更多
BACKGROUND: Road traffi c accidents(RTA) are responsible for 1.2 million deaths worldwide each year. RTA will become the 3rd largest contributor to the global burden of diseases after ischemic heart diseases(IHD) and ...BACKGROUND: Road traffi c accidents(RTA) are responsible for 1.2 million deaths worldwide each year. RTA will become the 3rd largest contributor to the global burden of diseases after ischemic heart diseases(IHD) and depression. We conducted a retrospective study on RTA in a tertiary center in the hilly district of Uttarakhand in India.METHODS: The number of RTA, pattern of RTA, the number of patients killed and injured, the pattern of injury causing death and disability, the severity of accidents, and the type of disability were noted from December 2009 to November 2011. The accident severity was calculated as the number of patients killed per 100 accidents. The methods for reducing the incidence of RTA were observed, and the role of policy makers was studied.RESULTS: The majority of deaths and disabilities in Uttarakhand were due to road traffic accidents in the hilly districts of the states. The most common cause of RTA was driving fault followed by defective roads.CONCLUSION: Proper designing of roads and minimizing the fault of drivers are essential to prevent road traffi c accidents in hilly regions.展开更多
Evapotranspiration is an important parameter used to characterize the water cycle of ecosystems.To under-stand the properties of the evapotranspiration and energy balance of a subalpine forest in the southeastern Qing...Evapotranspiration is an important parameter used to characterize the water cycle of ecosystems.To under-stand the properties of the evapotranspiration and energy balance of a subalpine forest in the southeastern Qinghai-Tibet Plateau,an open-path eddy covariance system was set up to monitor the forest from November 2020 to October 2021 in a core area of the Three Parallel Rivers in the Qing-hai-Tibet Plateau.The results show that the evapotranspira-tion peaked daily,the maximum occurring between 11:00 and 15:00.Environmental factors had significant effects on evapotranspiration,among them,net radiation the greatest(R^(2)=0.487),and relative humidity the least(R^(2)=0.001).The energy flux varied considerably in different seasons and sensible heat flux accounted for the main part of turbulent energy.The energy balance ratio in the dormant season was less than that in the growing season,and there is an energy imbalance at the site on an annual time scale.展开更多
Pinus sylvestris var.mongolica(P.sylvestris)plantations are extensively established in the boreal zone.Increasing stand biomass of these plantations can effectively enhance carbon stock,which is crucial for mitigating...Pinus sylvestris var.mongolica(P.sylvestris)plantations are extensively established in the boreal zone.Increasing stand biomass of these plantations can effectively enhance carbon stock,which is crucial for mitigating climate change.However,the current understanding of optimizing plantation strategies to maximize stand biomass is primarily derived from experiments in tropical and subtropical zones,which is difficult to extend to the boreal due to substantial climatic differences.Based on a comprehensive dataset from 1,076 sample plots of P.sylvestris plantations in the boreal zone of China,we evaluated the effects of tree species richness and stand density on tree height,diameter at breast height(DBH),and stand biomass to investigate the optimal plantation strategy.Furthermore,we examined how these effects changed with stand age and investigated their relative importance.We found that monocultures at a high stand density of 2,000–2,500ha^(−1) were the optimal plantation strategy to maximize stand biomass(107.5Mg·ha^(−1)),and this held true at almost all stand ages.Unfortunately,this strategy resulted in low species richness and small individual trees(10.6m height and 9.8cm DBH),thus presenting a trade-off.In addition,as stand age increased,the effect of tree species richness on stand biomass shifted from positive to negative,but the effect of stand density was always positive.Overall,stand age had the greatest effect on stand biomass,followed by stand density and then tree species richness.Our findings reveal a distinct plantation strategy for optimizing stand biomass of P.sylvestris plantations in the boreal zone.More importantly,this study highlights that(1)maximizing stand biomass in the boreal zone may compromise tree species richness;(2)net effects of tree species richness on stand biomass are not always positive,as negative selection effects offset positive complementary effects.展开更多
The efficient pyrolysis and conversion of organic matter in organic-rich shale,as well as the effective recovery of pyrolysis shale oil and gas,play a vital role in alleviating energy pressure.The state of carbon diox...The efficient pyrolysis and conversion of organic matter in organic-rich shale,as well as the effective recovery of pyrolysis shale oil and gas,play a vital role in alleviating energy pressure.The state of carbon dioxide(CO_(2))in the pyrolysis environment of shale reservoirs is the supercritical state.Its unique supercritical fluid properties not only effectively heat organic matter,displace pyrolysis products and change shale pore structure,but also achieve carbon storage to a certain extent.Shale samples were made into powder and three sizes of cores,and nitrogen(N_(2))and supercritical carbon dioxide(ScCO_(2))pyrolysis experiments were performed at different final pyrolysis temperatures.The properties and mineral characteristics of the pyrolysis products were studied based on gas chromatography analysis,Xray diffraction tests,and mass spectrometry analysis.Besides,the pore structure characteristics at different regions of cores before and after pyrolysis were analyzed using N_(2) adsorption tests to clarify the impact of fracturing degree on the pyrolysis effect.The results indicate that the optimal pyrolysis temperature of Longkou shale is about 430℃.Compared with N_(2),the oil yield of ScCO_(2) pyrolysis is higher.The pyrolysis oil obtained by ScCO_(2) extraction has more intermediate fractions and higher relative molecular weight.The ScCO_(2) can effectively improve the pore diameter of shale and its effect is better than that of N_(2).The micropores are produced in shale after pyrolysis,and the macropores only are generated in ScCO_(2) pyrolysis environments with temperatures greater than 430℃.The pore structure has different development characteristics at different pyrolysis temperatures,which are mainly affected by the pressure holding of volatile matter and products blocking.Compared to the surface of the core,the pore development effect inside the core is better.With the decrease in core size,the pore diameter,specific surface area,and pore volume of cores all increase after pyrolysis.展开更多
文摘Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying available cold wind in cold regions.This is achieved by a static heat transfer device called thermosyphon equipped with an air insulation layer.A refrigeration unit can be optionally integrated to meet additional cooling requirements.The introduction of air insulation isolates the thermosyphon from ground zones where freezing is not needed,resulting in:(1)steering the cooling resources(cold wind or refrigeration)towards zones of interest;and(2)minimizing refrigeration load.This design is demonstrated using well-validated mathematical models from our previous work based on two-phase enthalpy method of the ground coupled with a thermal resistance network for the thermosyphon.Two Canadian mines are considered:the Cigar Lake Mine and the Giant Mine.The results show that our proposed design can speed the freezing time by 30%at the Giant Mine and by two months at the Cigar Lake Mine.Further,a cooling load of 2.4 GWh can be saved at the Cigar Lake Mine.Overall,this study provides mining practitioners with sustainable solutions of underground AGF.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12275179,12005079,and 41975100),the Shanghai Natural Science Foundation of China(Grant No.21ZR1443900),Natural Science Foundation of Jiangsu Province(Grant No.BK20220511),the funding for Scientific Research Startup of Jiangsu University(Grant No.4111710001),and the Joint Research Project for Meteorological Capacity Improvement(Grant No.22NLTSZ004).
文摘Abrupt temperature volatility has detrimental effects on daily activities,macroeconomic growth,and human health.Predicting abrupt temperature volatility and thus diminishing its negative impacts can be achieved by exploring homogeneous regions of temperature volatility and analyzing the driving factors.To investigate the regionalization of temperature volatility in China's mainland,a network constructed by the cosine similarity of temperature volatility series from China's mainland was embedded in hyperbolic space.Subsequently,we partitioned the network on the hyperbolic map using the critical gap method and then found eight regions in all.Ultimately,a network of communities was constructed while the interaction among communities was quantified.This yields a perspective of temperature volatility regionalization that can accurately reflect factors including altitude,climate type,and the geographic location of mountains.Further analysis demonstrates that the regionalization in the hyperbolic map is distinct from provinces and has a realistic basis:communities in southwest China show strong correlations due to the temperature sensitivity to altitude,and communities in northern China show a convergence in the area of Dingxi,Gansu,mainly owing to the strong temperature sensitivity to climate types.As a consequence,node distributions and community divisions in the hyperbolic map can offer new insights into the regionalization of temperature volatility in China's mainland.The results demonstrate the potential of hyperbolic embedding of complex networks in forecasting future node associations in real-world data.
基金supported by State Grid science and technology projects“Research on energy and power sup-ply and demand interactive simulation technology for new power system(5100-202257028A-1-1-ZN)”.
文摘Increasing interest has been directed toward the potential of heterogeneous flexible loads to mitigate the challenges associated with the increasing variability and uncertainty of renewable generation.Evaluating the aggregated flexible region of load clusters managed by load aggregators is the crucial basis of power system scheduling for the system operator.This is because the aggregation result affects the qual-ity of the scheduling schemes.A stringent computation based on the Minkowski sum is NP-hard,whereas existing approximation meth-ods that use a special type of polytope exhibit limited adaptability when aggregating heterogeneous loads.This study proposes a stringent internal approximation method based on the convex hull of multiple layers of maximum volume boxes and embeds it into a day-ahead scheduling optimization model.The numerical results indicate that the aggregation accuracy can be improved compared with methods based on one type of special polytope,including boxes,zonotopes,and homothets.Hence,the reliability and economy of the power sys-tem scheduling can be enhanced.
基金National Natural Sci-ence Foundation of China (Grant No. 39900084) and KZCX1-10-07.
文摘Using the multi-temporal Landsat data and survey data of national resources, the authors studied the dynamics of cultivated land and landcover changes of typical ecological regions in China. The results of investigation showed that the whole distribution of the cultivated land shifted to Northeast and Northwest China, and as a result, the ecological quality of cultivated land dropped down. The seacoast and cultivated land in the area of Yellow River Mouth expanded by an increasing rate of 0.73 kma-1, with a depositing rate of 2.1 kma-1. The desertification area of the dynamic of Horqin Sandy Land increased from 60.02% of the total land area in1970s to 64.82% in1980s but decreased to 54.90% in early 1990s. As to the change of North Tibet lakes, the water area of the Namu Lake decreased by 38.58 km2 from year 1970 to 1988, with a decreasing rate of 2.14 km2a-1.
基金supported by the National Natural Science Foundation of China (Grant No 10647001)the Guangxi Natural Science Foundation (Grant No 0728042)+1 种基金the Program for Excellent Talents in Guangxi Higher Education Institutions (Grant No RC2007006)the NSFC-HK Joint Research Scheme (Grant No N-CityU107/07)
文摘This paper studies pinning-controlled synchronization of complex networks with bounded or unbounded synchronized regions. To study a state-feedback pinning-controlled network with N nodes, it first converts the controlled network to an extended network of N＋1 nodes without controls. It is shown that the controlled synchronizability of the given network is determined by the real part of the smallest nonzero eigenvalue of the coupling matrix of its extended network when the synchronized region is unbounded; but it is determined by the ratio of the real parts of the largest and the smallest nonzero eigenvalues of the coupling matrix when the synchronized region is bounded. Both theoretical analysis and numerical simulation show that the portion of controlled nodes has no critical values when the synchronized region is unbounded, but it has a critical value when the synchronized region is bounded. In the former case, therefore, it is possible to control the network to achieve synchronization by pinning only one node. In the latter case, the network can achieve controlled synchronization only when the portion of controlled nodes is larger than the critical value.
文摘A geometric framework is proposed for semiparametric nonlinear regression models based on the concept of least favorable curve, introduced by Severini and Wong (1992). The authors use this framework to drive three kinds of improved approximate confidence regions for the parameter and parameter subset in terms of curvatures. The results obtained by Hamilton et al. (1982), Hamilton (1986) and Wei (1994) are extended to semiparametric nonlinear regression models.
文摘The object of this article is to introduce new classes of meromorphic functions associated with conic regions. Several properties like the coefficient bounds, growth and distortion theorems, radii of starlikeness and convexity, partial sums, are investigated. Some consequences of the main results for the well-known classes of meromorphic functions are also pointed out.
基金the sponsor by the National Natural Science Foundation of China (No. 50974115)the Program of Introducing Talents of Discipline to Universities (No.B07028)
文摘The coal industry in China has been moving from the semiarid eastern to the drier western regions since the beginning of this century.Water protection is of the utmost concern for coal mining in these regions.Lu'an,as one of the state coal mining bases in China,has been seeing increasingly heavier pressure for the protection of water resources.This article considers Lu'an as an example and describes the ways these concerns may be alleviated.High mine-water utilization rates have effectively reduced wasting of water and,consequently,have reduced water demand.Using the top layers of the Ordavician as aquifuge barriers can prevent floor karst water inrush into the longwall face and can protect the regional Ordovician karst water resources at the same time.The strength of the overlying Quaternary clay can protect against roof collapse and has successfully preserved the Quaternary porous water resource.
文摘Self-biting disease occurred in most farmed fur animals in the world. The mechanism and rapid detection method of this disease has not been reported. We applied bulked sergeant analysis （BSA） in combination with RAPD method to analyze a molecular genetic marker linked with self-biting trait in mink group. The molecular marker was converted into sequence-characterized amplified regions （SCAR） marker for rapid detection of this disease. A single RAPD marker A8 amplified a specific band of 263bp in self-biting minks, which was designated as SRA8-250, and non-specific band of 315bp in both self-biting and healthy minks. The sequences of the bands exhibited 75% and 88% similarity to Canis familiarizes major histocompatibility complex （MHC） class II region and Macaca mulatta MHC class I region, respectively. A SCAR marker SCAR-A8 was designed for the specific fragment SRA8-250 and validated in 30 self-biting minks and 30 healthy minks. Positive amplification of SCAR-A8 was detected in 24 self-biting minks and 12 healthy minks. χ2 test showed significant difference （p〈0.01） in the detection rate between the two groups. This indicated that SRA8-250 can be used as a positive marker to detect self-biting disease in minks. Furthermore, the finding that self-biting disease links with MHC genes has significant implications for the mechanism of the disease.
文摘Forest ecosystem is one of the most important ecosystems in the world that human-beings rely on. Forest harvesting policy is one of the main criteria indicating how and how much the human beings open up and make use offorest. Whether the policy is reasonable or not has high relations with not only the increasing or decreasing of forest system,but also the development speed of human society. In this paper, the author analyzed the development of interaction between human society and forest ecosystem from ancient times to today. Then author stated that the rational harvesting policy should be the harvesting sequences of both harvesting density and harvesting time, which might result in the maximumcomprehensive benefit, including economical profit, social benefit and ecological benefit, of forest to human society. Atlast, according to the analysis of interaction bctween human-beings and her environment, the prediction analysis for humansociety development in forest regions in the future was prescnted using Entropy Growing Analysis.
文摘This paper constructs a set of confidence regions of parameters in terms of statistical curvatures for AR(q) nonlinear regression models. The geometric frameworks are proposed for the model. Then several confidence regions for parameters and parameter subsets in terms of statistical curvatures are given based on the likelihood ratio statistics and score statistics. Several previous results, such as [1] and [2] are extended to AR(q) nonlinear regression models.
文摘The weighted Sobolev-Lions type spaces W pl,γ（Ω; E0, E） = W pl,γ（Ω; E） ∩ Lp,γ （Ω; E0） are studied, where E0, E are two Banach spaces and E0 is continuously and densely embedded on E. A new concept of capacity of region Ω ∈ Rn in W pl,γ（; E0, E） is introduced. Several conditions in terms of capacity of region Ω and interpolations of E0 and E are found such that ensure the continuity and compactness of embedding operators. In particular, the most regular class of interpolation spaces Eα between E0 and E, depending of α and l, are found such that mixed differential operators Dα are bounded and compact from W pl,γ（Ω; E0, E） to Eα-valued Lp,γ spaces. In applications, the maximal regularity for differential-operator equations with parameters are studied.
基金financially supported by the National Natural Science Foundation of China(31972149)funding support from the MacDiarmid Institute for Advanced Materials and Nanotechnologythe Dodd-Walls Centre for Photonic and Quantum Technologies。
文摘Herein,a novel interference-free surface-enhanced Raman spectroscopy(SERS)strategy based on magnetic nanoparticles(MNPs)and aptamer-driven assemblies was proposed for the ultrasensitive detection of histamine.A core-satellite SERS aptasensor was constructed by combining aptamer-decorated Fe_(3)O_(4)@Au MNPs(as the recognize probe for histamine)and complementary DNA-modified silver nanoparticles carrying 4-mercaptobenzonitrile(4-MBN)(Ag@4-MBN@Ag-c-DNA)as the SERS signal probe for the indirect detection of histamine.Under an applied magnetic field in the absence of histamine,the assembly gave an intense Raman signal at“Raman biological-silent”region due to 4-MBN.In the presence of histamine,the Ag@4-MBN@Ag-c-DNA SERS-tag was released from the Fe_(3)O_(4)@Au MNPs,thus decreasing the SERS signal.Under optimal conditions,an ultra-low limit of detection of 0.65×10^(-3)ng/mL and a linear range 10^(-2)-10^5 ng/mL on the SERS aptasensor were obtained.The histamine content in four food samples were analyzed using the SERS aptasensor,with the results consistent with those determined by high performance liquid chromatography.The present work highlights the merits of indirect strategies for the ultrasensitive and highly selective SERS detection of small biological molecules in complex matrices.
基金Supported by the National Natural Science Foundation of China under Grant No 51506051the National Basic Research Program of China under Grant No 2015CB251503the Fundamental Research Funds for the Central Universities under Grant No JB2015RCY04
文摘There are numerous formulae relating to the predictions of sound wave in the cavitating and bubbly flows. However, tile valid regions of those formulae are rather unclear from the view point of physics. In this work, the validity of the existing formulae is discussed in terms of three regions by employing the analysis of three typical lengths involved （viscous length, thermal diffusion length and bubble radius）. In our discussions, viscosity and thermal diffusion are both considered together with the effects of relative motion between bubbles and liquids. The importance of relative motion and thermal diffusion are quantitatively discussed in a wide range of parameter zones （including bubble radius and acoustic frequency）, The results show that for large bubbles, the effects of relative motion will be prominent in a wide region.
文摘Up to date information about the existing land cover patterns and changes in land cover over time is one of the prime prerequisites for the preparation of an integrated development plan and economic development program of a region. By using ETM＋ image data from 2002, we provided a land cover map of deciduous forest regions in Azerbaijan Province, Iran. Initial qualitative evaluation of the data showed no significant radiometric errors. Image classification was carried out using a maximum likelihood-based supervised classification method. In the end, we determined five major land cover classes, i.e., grass lands, deciduous broad-leaf forest, cultivated land, river and land without vegetation cover. Accuracy, estimated by the use of criteria such as overall accuracy from a confusion matrix of classification was 86% with a 0.88 Kappa coefficient. Such high accuracy results demonstrate that the combined use of spectral and textural characteristics increased the number of classes in the field classification, also with excellent accuracy. The availability and use of time series of remote sensing data permit the detection and quantification of land cover changes and improve our understanding of the past and present status of forest ecosystems.
基金Supported by the National Natural Science Foundation Project(92255302)National Science and Technology Major Project(2016ZX05029005)Scientific Research and Technological Development Project of PetroChina(2021DJ31).
文摘Based on seismic,drilling,and source rock analysis data,the petroleum geological characteristics and future exploration direction of the oil-rich sags in the Central and West African Rift System(CWARS)are discussed.The study shows that the Central African Rift System mainly develops high-quality lacustrine source rocks in the Lower Cretaceous,and the West African Rift System mainly develops high-quality terrigenous organic matter-rich marine source rocks in the Upper Cretaceous,and the two types of source rocks provide a material basis for the enrichment of oil and gas in the CWARS.Multiple sets of reservoir rocks including fractured basement and three sets of regional cap rocks in the Lower Cretaceous,the Upper Cretaceous,and the Paleogene are developed in the CWARS.Since the Late Mesozoic,due to the geodynamic factors including the dextral strike-slip movement of the Central African Shear Zone,the basins in different directions of the CWARS differ in terms of rifting stages,intervals of regional cap rocks,trap types and accumulation models.The NE-SW trending basins have mainly preserved one stage of rifting in the Early Cretaceous,with regional cap rocks developed in the Lower Cretaceous strata,forming traps of reverse anticlines,flower-shaped structures and basement buried hill,and two types of hydrocarbon accumulation models of"source and reservoir in the same formation,and accumulation inside source rocks"and"up-source and down-reservoir,and accumulation below source rocks".The NW–SE basins are characterized by multiple rifting stages superimposition,with the development of regional cap rocks in the Upper Cretaceous and Paleogene,forming traps of draping anticlines,faulted anticlines,antithetic fault blocks and the accumulation model of"down-source and up-reservoir,and accumulation above source rocks".The combination of reservoir and cap rocks inside source rocks of basins with multiple superimposed rifting stages,as well as the lithologic reservoirs and the shale oil inside source rocks of strong inversion basins are important fields for future exploration in basins of the CWARS.
文摘BACKGROUND: Road traffi c accidents(RTA) are responsible for 1.2 million deaths worldwide each year. RTA will become the 3rd largest contributor to the global burden of diseases after ischemic heart diseases(IHD) and depression. We conducted a retrospective study on RTA in a tertiary center in the hilly district of Uttarakhand in India.METHODS: The number of RTA, pattern of RTA, the number of patients killed and injured, the pattern of injury causing death and disability, the severity of accidents, and the type of disability were noted from December 2009 to November 2011. The accident severity was calculated as the number of patients killed per 100 accidents. The methods for reducing the incidence of RTA were observed, and the role of policy makers was studied.RESULTS: The majority of deaths and disabilities in Uttarakhand were due to road traffic accidents in the hilly districts of the states. The most common cause of RTA was driving fault followed by defective roads.CONCLUSION: Proper designing of roads and minimizing the fault of drivers are essential to prevent road traffi c accidents in hilly regions.
基金supported by the CAS"Light of West China"Program (2021XBZG-XBQNXZ-A-007)the National Natural Science Foundation of China (31971436)the State Key Laboratory of Cryospheric Science,Northwest Institute of Eco-Environment and Resources,Chinese Academy Sciences (SKLCS-OP-2021-06).
文摘Evapotranspiration is an important parameter used to characterize the water cycle of ecosystems.To under-stand the properties of the evapotranspiration and energy balance of a subalpine forest in the southeastern Qinghai-Tibet Plateau,an open-path eddy covariance system was set up to monitor the forest from November 2020 to October 2021 in a core area of the Three Parallel Rivers in the Qing-hai-Tibet Plateau.The results show that the evapotranspira-tion peaked daily,the maximum occurring between 11:00 and 15:00.Environmental factors had significant effects on evapotranspiration,among them,net radiation the greatest(R^(2)=0.487),and relative humidity the least(R^(2)=0.001).The energy flux varied considerably in different seasons and sensible heat flux accounted for the main part of turbulent energy.The energy balance ratio in the dormant season was less than that in the growing season,and there is an energy imbalance at the site on an annual time scale.
基金supported by the National Key Research and Development Program of China(No.2022YFF1300500)the Youth Innovation Promotion Association of CAS(No.2022195).
文摘Pinus sylvestris var.mongolica(P.sylvestris)plantations are extensively established in the boreal zone.Increasing stand biomass of these plantations can effectively enhance carbon stock,which is crucial for mitigating climate change.However,the current understanding of optimizing plantation strategies to maximize stand biomass is primarily derived from experiments in tropical and subtropical zones,which is difficult to extend to the boreal due to substantial climatic differences.Based on a comprehensive dataset from 1,076 sample plots of P.sylvestris plantations in the boreal zone of China,we evaluated the effects of tree species richness and stand density on tree height,diameter at breast height(DBH),and stand biomass to investigate the optimal plantation strategy.Furthermore,we examined how these effects changed with stand age and investigated their relative importance.We found that monocultures at a high stand density of 2,000–2,500ha^(−1) were the optimal plantation strategy to maximize stand biomass(107.5Mg·ha^(−1)),and this held true at almost all stand ages.Unfortunately,this strategy resulted in low species richness and small individual trees(10.6m height and 9.8cm DBH),thus presenting a trade-off.In addition,as stand age increased,the effect of tree species richness on stand biomass shifted from positive to negative,but the effect of stand density was always positive.Overall,stand age had the greatest effect on stand biomass,followed by stand density and then tree species richness.Our findings reveal a distinct plantation strategy for optimizing stand biomass of P.sylvestris plantations in the boreal zone.More importantly,this study highlights that(1)maximizing stand biomass in the boreal zone may compromise tree species richness;(2)net effects of tree species richness on stand biomass are not always positive,as negative selection effects offset positive complementary effects.
基金supported by the National Natural Science Foundation of China (Nos.U22B6004,51974341)State Key Laboratory of Deep Oil and Gas (No.SKLDOG2024-ZYTS-14)the Fundamental Research Funds for the Central Universities (No.20CX06070A)。
文摘The efficient pyrolysis and conversion of organic matter in organic-rich shale,as well as the effective recovery of pyrolysis shale oil and gas,play a vital role in alleviating energy pressure.The state of carbon dioxide(CO_(2))in the pyrolysis environment of shale reservoirs is the supercritical state.Its unique supercritical fluid properties not only effectively heat organic matter,displace pyrolysis products and change shale pore structure,but also achieve carbon storage to a certain extent.Shale samples were made into powder and three sizes of cores,and nitrogen(N_(2))and supercritical carbon dioxide(ScCO_(2))pyrolysis experiments were performed at different final pyrolysis temperatures.The properties and mineral characteristics of the pyrolysis products were studied based on gas chromatography analysis,Xray diffraction tests,and mass spectrometry analysis.Besides,the pore structure characteristics at different regions of cores before and after pyrolysis were analyzed using N_(2) adsorption tests to clarify the impact of fracturing degree on the pyrolysis effect.The results indicate that the optimal pyrolysis temperature of Longkou shale is about 430℃.Compared with N_(2),the oil yield of ScCO_(2) pyrolysis is higher.The pyrolysis oil obtained by ScCO_(2) extraction has more intermediate fractions and higher relative molecular weight.The ScCO_(2) can effectively improve the pore diameter of shale and its effect is better than that of N_(2).The micropores are produced in shale after pyrolysis,and the macropores only are generated in ScCO_(2) pyrolysis environments with temperatures greater than 430℃.The pore structure has different development characteristics at different pyrolysis temperatures,which are mainly affected by the pressure holding of volatile matter and products blocking.Compared to the surface of the core,the pore development effect inside the core is better.With the decrease in core size,the pore diameter,specific surface area,and pore volume of cores all increase after pyrolysis.
