Regularization method is an effective method for solving ill\|posed equation. In this paper the unbiased estimation formula of unit weight standard deviation in the regularization solution is derived and the formula i...Regularization method is an effective method for solving ill\|posed equation. In this paper the unbiased estimation formula of unit weight standard deviation in the regularization solution is derived and the formula is verified with numerical case of 1 000 sample data by use of the typical ill\|posed equation, i.e. the Fredholm integration equation of the first kind.展开更多
This study explores the combination of ultrasound technology with a detection algorithm to categorize flow regimes in bubble columns used for aeration in aquaculture.An ultrasonic velocity profiler is used to obtain t...This study explores the combination of ultrasound technology with a detection algorithm to categorize flow regimes in bubble columns used for aeration in aquaculture.An ultrasonic velocity profiler is used to obtain the standard deviation of the bubble velocity distributed throughout the column.The bubble velocity data for three known flow regimes were used to develop a probability density function(PDF)classification model.The experimental apparatus consisted of a circular tank equipped with a bubble generator and gas hold-up monitoring systems.The flow regimes of the experimental fluid were determined,and the classification was conducted via the PDF method.The results demonstrate that the classification accuracy is not lower than that of traditional machine learning methods.展开更多
Most edge-detection methods rely on calculating gradient derivatives of the potential field, a process that is easily affected by noise and is therefore of low stability. We propose a new edge-detection method named c...Most edge-detection methods rely on calculating gradient derivatives of the potential field, a process that is easily affected by noise and is therefore of low stability. We propose a new edge-detection method named correlation coefficient of multidirectional standard deviations（CCMS） that is solely based on statistics. First, we prove the reliability of the proposed method using a single model and then a combination of models. The proposed method is evaluated by comparing the results with those obtained by other edge-detection methods. The CCMS method offers outstanding recognition, retains the sharpness of details, and has low sensitivity to noise. We also applied the CCMS method to Bouguer anomaly data of a potash deposit in Laos. The applicability of the CCMS method is shown by comparing the inferred tectonic framework to that inferred from remote sensing（RS） data.展开更多
The size distribution of the broken top coal blocks is an important factor,affecting the recovery ratio and the efficiency of drawing top coal in longwall top coal caving(LTCC)mining panel.The standard deviation of to...The size distribution of the broken top coal blocks is an important factor,affecting the recovery ratio and the efficiency of drawing top coal in longwall top coal caving(LTCC)mining panel.The standard deviation of top coal block size(dt)is one of the main parameters to reflect the size distribution of top coal.To find the effect of dt on the caving mechanism,this study simulates experiments with 9 different dt by using discrete element software PFC.The dt is divided into two stages:uniform distribution stage(UDS)whose dt is less than 0.1(Schemes 1–5),and nonuniform distribution stage(NDS)whose dt is more than 0.1(Schemes 6–9).This research mainly investigates the variation of recovery ratio,drawing body shape,boundary of top coal,and contact force between particles in the two stages,respectively.The results showed that with the increasing dt,the recovery ratio of the panel increases first and then decreases in UDS.It is the largest in Scheme 3,which mainly increases the drawing volume at the side of starting drawing end.However,the recovery ratio decreases first and then increases quickly in NDS,and it is the largest in Scheme 9,where the drawing volume at the side of finishing drawing end are relatively higher.In UDS,the major size of top coal is basically medium,while in NDS,the size varies from medium to small,and then to large,with a distinct difference in shape and volume of the drawing body.When the major size of top coal is medium and small,the cross-section width of the initial boundary of top coal at each height is relatively small.Conversely,when the top coal size is large,the initial boundary of top coal has a larger opening range,the rotating angle of lower boundary is relatively small in the normal drawing stage,which is conducive to the development of drawing body and reduces the residual top coal,and the maximum particle velocity and the particles movement angle are both larger.This study lays a foundation for the prediction of recovery ratio,and suggests that the uniform top coal is more manageable and has a larger recovery ratio.展开更多
AIM:To evaluate whether glaucomatous visual field defect particularly the pattern standard deviation(PSD)of Humphrey visual field could be associated with visual evoked potential(VEP)parameters of patients having prim...AIM:To evaluate whether glaucomatous visual field defect particularly the pattern standard deviation(PSD)of Humphrey visual field could be associated with visual evoked potential(VEP)parameters of patients having primary open angle glaucoma(POAG).METHODS:Visual field by Humphrey perimetry and simultaneous recordings of pattern reversal visual evoked potential(PRVEP)were assessed in 100 patients with POAG.The stimulus configuration for VEP recordings consisted of the transient pattern reversal method in which a black and white checker board pattern was generated(full field)and displayed on VEP monitor(colour 14')by an electronic pattern regenerator inbuilt in an evoked potential recorder(RMS EMG EP MARK II).RESULTS:The results of our study indicate that there is a highly significant(P【0.001)negative correlation of P100 amplitude and a statistically significant(P【0.05)positive correlation of N70 latency,P100 latency and N155 latency with the PSD of Humphrey visual field in the subjects of POAG in various age groups as evaluated by Student’s t-test.CONCLUSION:Prolongation of VEP latencies were mirrored by a corresponding increase of PSD values.Conversely,as PSD increases the magnitude of VEP excursions were found to be diminished.展开更多
AIM： To compare four methods to approximate mean and standard deviation （SD） when only medians and interquartile ranges are provided.METHODS： We performed simulated meta-analyses on six datasets of 15, 30, 50, 100...AIM： To compare four methods to approximate mean and standard deviation （SD） when only medians and interquartile ranges are provided.METHODS： We performed simulated meta-analyses on six datasets of 15, 30, 50, 100, 500, and 1000 trials, respectively. Subjects were iteratively generated from one of the following seven scenarios： five theoreti-cal continuous distributions [Normal, Normal （0, 1）, Gamma, Exponential, and Bimodal] and two real-life distributions of intensive care unit stay and hospital stay. For each simulation, we calculated the pooled estimates assembling the study-specific medians and SD approximations： Conservative SD, less conservativeSD, mean SD, or interquartile range. We provided a graphical evaluation of the standardized differences.To show which imputation method produced the best estimate, we ranked those differences and calculated the rate at which each estimate appeared as the best, second-best, third-best, or fourth-best.RESULTS： Our results demonstrated that the best pooled estimate for the overall mean and SD was provided by the median and interquartile range （mean standardized estimates： 4.5 ± 2.2, P = 0.14） or by the median and the SD conservative estimate （mean standardized estimates： 4.5 ± 3.5, P = 0.13）. The less conservative approximation of SD appeared to be the worst method, exhibiting a significant difference from the reference method at the 90% confidence level. The method that ranked first most frequently is the interquartile range method （23/42 = 55%）, particularly when data were generated according to the Standard Normal, Gamma, and Exponential distributions. The second-best is the conservative SD method （15/42 = 36%）, particularly for data from a bimodal distributionand for the intensive care unit stay variable. CONCLUSION： Meta-analytic estimates are not signi-fcantly affected by approximating the missing values ofmean and SD with the correspondent values for medianand interquartile range.展开更多
Two additional features are particularly useful in pixelwise satellite data segmentation using neural networks: one results from local window averaging around each pixel (MWA) and another uses a standard deviation est...Two additional features are particularly useful in pixelwise satellite data segmentation using neural networks: one results from local window averaging around each pixel (MWA) and another uses a standard deviation estimator (MWSD) instead of the average. While the former’s complexity has already been solved to a satisfying minimum, the latter did not. This article proposes a new algorithm that can substitute a <i><span style="font-family:Verdana;">naive</span></i><span style="font-family:Verdana;"> MWSD, by making the complexi</span><span><span style="font-family:Verdana;">ty of the computational process fall from </span><i><span style="font-family:Verdana;">O</span></i><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">N</span></i><sup><span style="font-family:Verdana;">2</span></sup><i><span style="font-family:Verdana;">n</span></i><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">) to </span><i><span style="font-family:Verdana;">O</span></i><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">N</span></i></span><sup><span style="font-family:Verdana;">2</span></sup><i><span style="font-family:Verdana;">n</span></i><span style="font-family:Verdana;">)</span><span style="font-family:Verdana;">, where </span><i><span style="font-family:Verdana;">N</span></i><span style="font-family:Verdana;"> is a square</span></span><span style="font-family:Verdana;"> input array side, and </span><i><span style="font-family:Verdana;">n</span></i><span style="font-family:Verdana;"> is the moving window’s side length. The Num</span><span style="font-family:Verdana;">ba python compiler was used to make python a competitive high-performance</span> <span style="font-family:Verdana;">computing language in our optimizations. Our results show efficiency benchmars</span>展开更多
Financial performance analysis is of vital importance those involved in a business(e.g.,shareholders,creditors,partners,and company managers).An accurate and appropriate performance measurement is critical for decisio...Financial performance analysis is of vital importance those involved in a business(e.g.,shareholders,creditors,partners,and company managers).An accurate and appropriate performance measurement is critical for decision-makers to achieve efficient results.Integrated performance measurement,by its nature,consists of multiple criteria with different levels of importance.Multiple Criteria Decision Analysis(MCDA)methods have become increasingly popular for solving complex problems,especially over the last two decades.There are different evaluation methodologies in the literature for selecting the most appropriate one among over 200 MCDA methods.This study comprehensively analyzed 41 companies traded on the Borsa Istanbul Corporate Governance Index for 10 quarters using SWARA,CRITIC,and SD integrated with eight different MCDA method algorithms to determine the position of Turkey's most transparent companies in terms of financial performance.In this study,we propose"stock returns"as a benchmark in comparing and evaluating MCDA methods.Moreover,we calculate the"rank reversal performance of MCDA methods".Finally,we performed a"standard deviation"analysis to identify the objective and characteristic trends for each method.Interestingly,all these innovative comparison procedures suggest that PROMETHEE II(preference ranking organization method for enrichment of evaluations II)and FUCA(Faire Un Choix Adéquat)are the most suitable MCDA methods.In other words,these methods produce a higher correlation with share price;they have fewer rank reversal problems,the distribution of scores they produce is wider,and the amount of information is higher.Thus,it can be said that these advantages make them preferable.The results show that this innovative methodological procedure based on'knowledge discovery'is verifiable,robust and efficient when choosing the MCDA method.展开更多
Land surface temperature(LST)is the key variable in land-atmosphere interaction,having an important impact on weather and climate forecasting.However,achieving consistent analysis of LST and the atmosphere in assimila...Land surface temperature(LST)is the key variable in land-atmosphere interaction,having an important impact on weather and climate forecasting.However,achieving consistent analysis of LST and the atmosphere in assimilation is quite challenging.This is because there is limited knowledge about the cross-component background error covariance(BEC)between LST and atmospheric state variables.This study aims to clarify whether there is a relationship between the error of LST and atmospheric variables,and whether this relationship varies spatially and temporally.To this end,the BEC coupled with atmospheric variables and LST was constructed(LST-BEC),and its characteristics were analyzed based on the 2023 mei-yu season.The general characteristics of LST-BEC show that the LST is mainly correlated with the atmospheric temperature and the correlation decreases gradually with a rise in atmospheric height,and the error standard deviation of the LST is noticeably larger than that of the low-level atmospheric temperature.The spatiotemporal characteristics of LST-BEC on the heavy-rain day and light-rain day show that the error correlation and error standard deviation of LST and low-level atmospheric temperature and humidity are closely related to the weather background,and also have obvious diurnal variations.These results provide valuable information for strongly coupled land-atmosphere assimilation.展开更多
The implementation of long-term shelterbelt programs in the middle reaches of the Yellow River(MRYR),China not only has improved the overall ecological environment,but also has led to the changes of land use pattern,c...The implementation of long-term shelterbelt programs in the middle reaches of the Yellow River(MRYR),China not only has improved the overall ecological environment,but also has led to the changes of land use pattern,causing carbon storage exchanges.However,the relationship between carbon storage and land use change in the MRYR is not concerned,which results in the uncertainty in the simulation of carbon storage in this area.Land use changes directly affect the carbon storage capacity of ecosystems,and as an indicator reflecting the overall state of land use,land use degree has an important relationship with carbon storage.In this study,land use data and the integrated valuation of ecosystem services and trade-offs(InVEST)model were used to assess the trends in land use degree and carbon storage in the MRYR during 1980-2020.The potential impact index and the standard deviation ellipse(SDE)algorithm were applied to quantify and analyze the characteristics of the impact of land use changes on carbon storage.Subsequently,land use transitions that led to carbon storage variations and their spatial variations were determined.The results showed that:(1)the most significant periods of carbon storage changes and land use transitions were observed during 1990-1995 and 1995-2020,with the most changed areas locating in the east of Fenhe River and in northwestern Henan Province;(2)the positive impact of land use degree on carbon storage may be related to the environmental protection measures implemented along the Yellow River,while the negative impact may be associated with the expansion of construction land in plain areas;and(3)the conversion of other land use types to grassland was the primary factor affecting carbon storage changes during 1980-2020.In future land use planning,attention should be given to the direction of grassland conversion,and focus on reasonably limiting the development of construction land.To enhance carbon storage,it will be crucial to increase the area of high-carbon-density land types,such as forest land and grassland under the condition that the area of permanent farmland does not decrease.展开更多
Reconstructing three-dimensional(3D)shapes from a single image remains a significant challenge in computer vision due to the inherent ambiguity caused by missing or occluded shape information.Previous studies have pre...Reconstructing three-dimensional(3D)shapes from a single image remains a significant challenge in computer vision due to the inherent ambiguity caused by missing or occluded shape information.Previous studies have predominantly focused on mesh models supervised by multi-view silhouettes.However,such methods are limited in reconstructing fine details.In this study,a 3D mesh model is predicted from a single image,leveraging depth consistency and without requiring viewpoint pose annotations.The model effectively learns strong shape priors that preserve finer structures and accurately predicts view poses from"correlation-supervised"viewpoints.Additionally,standard deviation and Laplacian losses were employed to regulate mesh edge distribution,resulting in more precise reconstructions.Differentiable renderer functions were derived from the 3D mesh to generate depth maps.Compared to conventional approaches,the proposed method provided superior representation of subtle structures.When applied to both synthetic and real-world datasets,the model outperformed existing methods in view-based 3D reconstruction tasks.展开更多
In patients with advanced cancer,the prevalence rate of cardiac autonomic neuropathy(CAN)is high,and the prognosis of patients with CAN is generally poor.Although mechanisms including inflammation,infection,metabolism...In patients with advanced cancer,the prevalence rate of cardiac autonomic neuropathy(CAN)is high,and the prognosis of patients with CAN is generally poor.Although mechanisms including inflammation,infection,metabolism,neurodegeneration,toxic processes,and cancer treatment have been proposed as etiologies of CAN in cancer patients,these mechanisms have not been completely elucidated,and their relationship has only been described indirectly.A study involving 127 cancer patients revealed that both the disease and its treatments can lead to a decrease in heart rate variability(HRV)indicating the autonomic imbalance.Because managing CAN is essential for improving the survival and quality of life of patients with cancer,patients and specialists can work together to customize cancer treatment and management using HRV as an index.展开更多
Eight temperate deciduous tree species, Acer rubrum L., A. saccharinum L., A. saccharum Marsh., Belluta alleghaniensis Britton., Fraxinus nigra Marsh., Quercus rubra L., Titia americana L., and Ulmus americana L. in e...Eight temperate deciduous tree species, Acer rubrum L., A. saccharinum L., A. saccharum Marsh., Belluta alleghaniensis Britton., Fraxinus nigra Marsh., Quercus rubra L., Titia americana L., and Ulmus americana L. in eastern North America, were selected to explore relationship between the northward distribution of temperate tree species and climatic factors. For each species, more than 30 sites at their north limits of distribution were obtained from their distribution maps, and 11 climatic indices at the north limits were computed. The standardized standard deviation (SD) method, which compares the magnitude of variance of climatic indices, was used to detect which climatic parameter was the most important for explaining northward distribution of these species. We presume that the climatic parameter that has the smallest variance at the north limit would be assigned as the dominant climatic factor for limiting the distribution of this species. The results derived from the standardized SD method indicated that the SD value of warmth index (WI) and/or annual biotemperature (ABT) were the smallest among the 11 climatic indices. Since both WI and ABT represent growing season temperature, it suggested that growing season temperature was the most important climatic factor for explaining the northward distribution of these temperate tree species. The relationships between several climatic indices, WI, coldness index (CI), annual precipitation (AP), annual range of temperature (ART) and humid/arid index were also analyzed. As a result, at the north limits of all these species, both WI and CI decreased with an increase of AP, and CI increased with an increase of ART. Besides growing season temperature, precipitation and climatic continentality also have influence on the northward distribution of the temperate trees in eastern North America.展开更多
In order to study the scale characteristics of heterogeneities in complex media, a random medium is constructed using a statistical method and by changing model parameters （autocorrelation lengths a and b）, the scal...In order to study the scale characteristics of heterogeneities in complex media, a random medium is constructed using a statistical method and by changing model parameters （autocorrelation lengths a and b）, the scales of heterogeneous geologic bodies in the horizontal and the vertical Cartesian directions may be varied in the medium. The autocorrelation lengths a and b represent the mean scale of heterogeneous geologic bodies in the horizontal and vertical Cartesian directions in the randQm medium, respectively. Based on this model, the relationship between model autocorrelation lengths and heterogeneous geologic body scales is studied by horizontal velocity variation and standard deviation. The horizontal velocity variation research shows that velocities are in random perturbation. The heterogeneous geologic body scale increases with increasing autocorrelation length. The recursion equation for the relationship between autocorrelation lengths and heterogeneous geologic body scales is determined from the velocity standard deviation research and the actual heterogeneous geologic body scale magnitude can be estimated by the equation.展开更多
Using conventional mathematical statistics,linear regression and the standard deviation,the quantitative analysis was made on the climate changes in Shenyang.The results showed that the trend of precipitation reduced ...Using conventional mathematical statistics,linear regression and the standard deviation,the quantitative analysis was made on the climate changes in Shenyang.The results showed that the trend of precipitation reduced 155 mm,which was made the greatest contribution by summer and autumn.It decreased 43 mm on the average after the climate jump.The precipitation variability in spring increased and drought risk in spring increased.The first soaking rain limited the spring planting time.The temperature trend raised 1.3℃,mainly in spring and winter.The frost-free period extended about 13 d.The accumulated temperature trends in crop growing season increased 290℃ and it had an average increase of 178℃ after the climate jump.This trend of climate warming made the end of last frost advanced.Early sowing of crops suitably was possible,which was beneficial for agricultural production.The precipitation decrease,the time delay and instability of the first soaking rain were unfavorable for crop growth and seeding.And they became the factors that constrained the normal growth and stabile yield raise of crops.展开更多
Using GIS spatial statistical analysis method, with ArcGIS software as an analysis tool, taking the diseased maize in Hedong District of Linyi City as the study object, the distribution characteristic of the diseased ...Using GIS spatial statistical analysis method, with ArcGIS software as an analysis tool, taking the diseased maize in Hedong District of Linyi City as the study object, the distribution characteristic of the diseased crops this time in spatial location was analyzed. The results showed that the diseased crops mainly dis- tributed along with river tributaries and downstream of main rivers. The correlation between adjacent diseased plots was little, so the infection of pests and diseases were excluded, and the major reason of incidence might be river pollution.展开更多
Based on slow- and fast-response measurements under neutral stratification conditions from a 325-m meteorological tower located in a built-up area of north-central Beijing as well as a descriptive survey of surface ro...Based on slow- and fast-response measurements under neutral stratification conditions from a 325-m meteorological tower located in a built-up area of north-central Beijing as well as a descriptive survey of surface roughness elements (i.e., buildings and trees) around the tower site, urban roughness lengths, zo, with zero-plane displacement height are estimated using logarithmic wind profile and morphometric methods in eight 45° directional sectors. When comparing their results with each other, the slow-response method tends to give smaller zo values. At a given location, considerable directional variations in values are observed. The effect of surface roughness on urban turbulence characteristics in terms of non-dimensional standard deviations of three-component velocity, σi/u*1 (where i = u, v, w and u*1 is local friction velocity), is investigated.展开更多
Changes of cultivated land patterns caused by major water conservation projects are rarely reported. We selected the Three Gorges Reservoir area in China to study the change in area and landscape pattern of the cultiv...Changes of cultivated land patterns caused by major water conservation projects are rarely reported. We selected the Three Gorges Reservoir area in China to study the change in area and landscape pattern of the cultivated land in the head,central, and tail areas of the reservoir that took place between 1992 and 2015;we then studied the spatial distribution of the cultivated land in the three parts of the reservoir;finally, we studied the driving forces behind the changes in the cultivated land. The results derived are as follows.(1) During the construction of the Three Gorges Project(TGP, 1992–2015), the area of cultivated land around the reservoir decreased by30.23 million ha. This reduction occurred in phases:the most severe change in cultivated land occurred during the later stage of the project(2002–2010);only 0.62 million ha of cultivated land did not change between 1992 and 2015.(2) Spatial pattern analysis showed that the cultivated land in the three parts of the reservoir changed from a northern distribution to a southern distribution;thus, the area of cultivated land in the north decreased over the time period. The area of cultivated land in the head and tail areas decreased by varying degrees, while it increased in the central area over the 23 years, indicating that the change in cultivated land showed regional differences.(3) The TGP, the policy of reverting farmland to forest,and urbanization were the main driving factors for the change of cultivated land, but there were differences in their impacts at different stages.(4) According to the patch dynamics of the land cover change, the degree of change gradually intensified during the early and later stages of the project and then stabilized during the operational period. Our research provides scientific support for the protection of cultivated land resources and food security in the reservoir area and for the coordination of social and economic development, which is of great significance to sustainable development in the reservoir area.展开更多
It is important to quantify and analyze forest spatial patterns for studying biological characteristics,population interaction and the relationship between the population and environment.In this study,the forest spati...It is important to quantify and analyze forest spatial patterns for studying biological characteristics,population interaction and the relationship between the population and environment.In this study,the forest spatial structure unit was generated based on the Delaunay triangulation model(DTM),and the weights were generated using the comprehensive values of the tree diameter at breast height,total height and crown width.The distance between neighbors determined by the DTM was weighted to transform the original coordinates of trees into logical coordinates.Then,a weighted spatial pattern(WSP)was developed.After weighting,the neighboring trees were replaced,the replacement ratio was 38.3%,and there was 57.4%of the central tree.Correlation analysis showed that the uniform angle index of the WSP was significantly correlated with the tree size standard deviation under uniformity(r=0.932)and randomness(r=0.711).The DTM method not only considers the spatial distance between trees,but also considers the non-spatial attributes of trees.By changing the spatial topological relation between trees,this method further improves the spatial structure measurement of forest.展开更多
Based on CAMP/Tibet [Coordinated Enhanced Observing Period （CEOP） Asia-Australia Monsoon Project （CAMP） on the Tibetan Plateau] turbulent data collected at the Bujiao （B J） site of the Nagqu area, the turbulent ...Based on CAMP/Tibet [Coordinated Enhanced Observing Period （CEOP） Asia-Australia Monsoon Project （CAMP） on the Tibetan Plateau] turbulent data collected at the Bujiao （B J） site of the Nagqu area, the turbulent structure and transportation characteristics in the near surface layer during summer are analyzed. The main results show that the relationship between the normalized standard deviation of 3D wind speed and stability satisfies the similarity law under both unstable and stable stratifications. The relations of normalized standard deviation of temperature and specific humidity to stability only obey the ＂-1/3 power law＂ under unstable conditions. In the case of stable stratifications, their relations to stability are dispersing. The sensible heat dominates in the dry period, while in the wet period, the latent heat is larger than the sensible heat.展开更多
文摘Regularization method is an effective method for solving ill\|posed equation. In this paper the unbiased estimation formula of unit weight standard deviation in the regularization solution is derived and the formula is verified with numerical case of 1 000 sample data by use of the typical ill\|posed equation, i.e. the Fredholm integration equation of the first kind.
基金supported by the Center of Excellence on Instru-mentation Technology and Automation(CEITA),Department of Instru-mentation and Electronics Engineering,Faculty of Engineering,King Mongkut’s University of Technology North Bangkok,Thailand。
文摘This study explores the combination of ultrasound technology with a detection algorithm to categorize flow regimes in bubble columns used for aeration in aquaculture.An ultrasonic velocity profiler is used to obtain the standard deviation of the bubble velocity distributed throughout the column.The bubble velocity data for three known flow regimes were used to develop a probability density function(PDF)classification model.The experimental apparatus consisted of a circular tank equipped with a bubble generator and gas hold-up monitoring systems.The flow regimes of the experimental fluid were determined,and the classification was conducted via the PDF method.The results demonstrate that the classification accuracy is not lower than that of traditional machine learning methods.
基金supported by the National Hi-Tech Research and Development Program of China(863 Program)(No.2006AA06Z107)the National Natural Science Foundation of China(No.40930314)
文摘Most edge-detection methods rely on calculating gradient derivatives of the potential field, a process that is easily affected by noise and is therefore of low stability. We propose a new edge-detection method named correlation coefficient of multidirectional standard deviations（CCMS） that is solely based on statistics. First, we prove the reliability of the proposed method using a single model and then a combination of models. The proposed method is evaluated by comparing the results with those obtained by other edge-detection methods. The CCMS method offers outstanding recognition, retains the sharpness of details, and has low sensitivity to noise. We also applied the CCMS method to Bouguer anomaly data of a potash deposit in Laos. The applicability of the CCMS method is shown by comparing the inferred tectonic framework to that inferred from remote sensing（RS） data.
基金supported by the National Key R&D Plan of China,China(Grant No.2018YFC0604501)the Natural Science Foundation of China,China(Grant Nos.51934008,51674264,51904305)the Research Fund of the State Key Laboratory of Coal Resources and Safe Mining,CUMT,China(Grant No.SKLCRSM19KF023).
文摘The size distribution of the broken top coal blocks is an important factor,affecting the recovery ratio and the efficiency of drawing top coal in longwall top coal caving(LTCC)mining panel.The standard deviation of top coal block size(dt)is one of the main parameters to reflect the size distribution of top coal.To find the effect of dt on the caving mechanism,this study simulates experiments with 9 different dt by using discrete element software PFC.The dt is divided into two stages:uniform distribution stage(UDS)whose dt is less than 0.1(Schemes 1–5),and nonuniform distribution stage(NDS)whose dt is more than 0.1(Schemes 6–9).This research mainly investigates the variation of recovery ratio,drawing body shape,boundary of top coal,and contact force between particles in the two stages,respectively.The results showed that with the increasing dt,the recovery ratio of the panel increases first and then decreases in UDS.It is the largest in Scheme 3,which mainly increases the drawing volume at the side of starting drawing end.However,the recovery ratio decreases first and then increases quickly in NDS,and it is the largest in Scheme 9,where the drawing volume at the side of finishing drawing end are relatively higher.In UDS,the major size of top coal is basically medium,while in NDS,the size varies from medium to small,and then to large,with a distinct difference in shape and volume of the drawing body.When the major size of top coal is medium and small,the cross-section width of the initial boundary of top coal at each height is relatively small.Conversely,when the top coal size is large,the initial boundary of top coal has a larger opening range,the rotating angle of lower boundary is relatively small in the normal drawing stage,which is conducive to the development of drawing body and reduces the residual top coal,and the maximum particle velocity and the particles movement angle are both larger.This study lays a foundation for the prediction of recovery ratio,and suggests that the uniform top coal is more manageable and has a larger recovery ratio.
文摘AIM:To evaluate whether glaucomatous visual field defect particularly the pattern standard deviation(PSD)of Humphrey visual field could be associated with visual evoked potential(VEP)parameters of patients having primary open angle glaucoma(POAG).METHODS:Visual field by Humphrey perimetry and simultaneous recordings of pattern reversal visual evoked potential(PRVEP)were assessed in 100 patients with POAG.The stimulus configuration for VEP recordings consisted of the transient pattern reversal method in which a black and white checker board pattern was generated(full field)and displayed on VEP monitor(colour 14')by an electronic pattern regenerator inbuilt in an evoked potential recorder(RMS EMG EP MARK II).RESULTS:The results of our study indicate that there is a highly significant(P【0.001)negative correlation of P100 amplitude and a statistically significant(P【0.05)positive correlation of N70 latency,P100 latency and N155 latency with the PSD of Humphrey visual field in the subjects of POAG in various age groups as evaluated by Student’s t-test.CONCLUSION:Prolongation of VEP latencies were mirrored by a corresponding increase of PSD values.Conversely,as PSD increases the magnitude of VEP excursions were found to be diminished.
文摘AIM： To compare four methods to approximate mean and standard deviation （SD） when only medians and interquartile ranges are provided.METHODS： We performed simulated meta-analyses on six datasets of 15, 30, 50, 100, 500, and 1000 trials, respectively. Subjects were iteratively generated from one of the following seven scenarios： five theoreti-cal continuous distributions [Normal, Normal （0, 1）, Gamma, Exponential, and Bimodal] and two real-life distributions of intensive care unit stay and hospital stay. For each simulation, we calculated the pooled estimates assembling the study-specific medians and SD approximations： Conservative SD, less conservativeSD, mean SD, or interquartile range. We provided a graphical evaluation of the standardized differences.To show which imputation method produced the best estimate, we ranked those differences and calculated the rate at which each estimate appeared as the best, second-best, third-best, or fourth-best.RESULTS： Our results demonstrated that the best pooled estimate for the overall mean and SD was provided by the median and interquartile range （mean standardized estimates： 4.5 ± 2.2, P = 0.14） or by the median and the SD conservative estimate （mean standardized estimates： 4.5 ± 3.5, P = 0.13）. The less conservative approximation of SD appeared to be the worst method, exhibiting a significant difference from the reference method at the 90% confidence level. The method that ranked first most frequently is the interquartile range method （23/42 = 55%）, particularly when data were generated according to the Standard Normal, Gamma, and Exponential distributions. The second-best is the conservative SD method （15/42 = 36%）, particularly for data from a bimodal distributionand for the intensive care unit stay variable. CONCLUSION： Meta-analytic estimates are not signi-fcantly affected by approximating the missing values ofmean and SD with the correspondent values for medianand interquartile range.
文摘Two additional features are particularly useful in pixelwise satellite data segmentation using neural networks: one results from local window averaging around each pixel (MWA) and another uses a standard deviation estimator (MWSD) instead of the average. While the former’s complexity has already been solved to a satisfying minimum, the latter did not. This article proposes a new algorithm that can substitute a <i><span style="font-family:Verdana;">naive</span></i><span style="font-family:Verdana;"> MWSD, by making the complexi</span><span><span style="font-family:Verdana;">ty of the computational process fall from </span><i><span style="font-family:Verdana;">O</span></i><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">N</span></i><sup><span style="font-family:Verdana;">2</span></sup><i><span style="font-family:Verdana;">n</span></i><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;">) to </span><i><span style="font-family:Verdana;">O</span></i><span><span style="font-family:Verdana;">(</span><i><span style="font-family:Verdana;">N</span></i></span><sup><span style="font-family:Verdana;">2</span></sup><i><span style="font-family:Verdana;">n</span></i><span style="font-family:Verdana;">)</span><span style="font-family:Verdana;">, where </span><i><span style="font-family:Verdana;">N</span></i><span style="font-family:Verdana;"> is a square</span></span><span style="font-family:Verdana;"> input array side, and </span><i><span style="font-family:Verdana;">n</span></i><span style="font-family:Verdana;"> is the moving window’s side length. The Num</span><span style="font-family:Verdana;">ba python compiler was used to make python a competitive high-performance</span> <span style="font-family:Verdana;">computing language in our optimizations. Our results show efficiency benchmars</span>
文摘Financial performance analysis is of vital importance those involved in a business(e.g.,shareholders,creditors,partners,and company managers).An accurate and appropriate performance measurement is critical for decision-makers to achieve efficient results.Integrated performance measurement,by its nature,consists of multiple criteria with different levels of importance.Multiple Criteria Decision Analysis(MCDA)methods have become increasingly popular for solving complex problems,especially over the last two decades.There are different evaluation methodologies in the literature for selecting the most appropriate one among over 200 MCDA methods.This study comprehensively analyzed 41 companies traded on the Borsa Istanbul Corporate Governance Index for 10 quarters using SWARA,CRITIC,and SD integrated with eight different MCDA method algorithms to determine the position of Turkey's most transparent companies in terms of financial performance.In this study,we propose"stock returns"as a benchmark in comparing and evaluating MCDA methods.Moreover,we calculate the"rank reversal performance of MCDA methods".Finally,we performed a"standard deviation"analysis to identify the objective and characteristic trends for each method.Interestingly,all these innovative comparison procedures suggest that PROMETHEE II(preference ranking organization method for enrichment of evaluations II)and FUCA(Faire Un Choix Adéquat)are the most suitable MCDA methods.In other words,these methods produce a higher correlation with share price;they have fewer rank reversal problems,the distribution of scores they produce is wider,and the amount of information is higher.Thus,it can be said that these advantages make them preferable.The results show that this innovative methodological procedure based on'knowledge discovery'is verifiable,robust and efficient when choosing the MCDA method.
基金sponsored by the National Natural Science Foundation of China[grant number U2442218]。
文摘Land surface temperature(LST)is the key variable in land-atmosphere interaction,having an important impact on weather and climate forecasting.However,achieving consistent analysis of LST and the atmosphere in assimilation is quite challenging.This is because there is limited knowledge about the cross-component background error covariance(BEC)between LST and atmospheric state variables.This study aims to clarify whether there is a relationship between the error of LST and atmospheric variables,and whether this relationship varies spatially and temporally.To this end,the BEC coupled with atmospheric variables and LST was constructed(LST-BEC),and its characteristics were analyzed based on the 2023 mei-yu season.The general characteristics of LST-BEC show that the LST is mainly correlated with the atmospheric temperature and the correlation decreases gradually with a rise in atmospheric height,and the error standard deviation of the LST is noticeably larger than that of the low-level atmospheric temperature.The spatiotemporal characteristics of LST-BEC on the heavy-rain day and light-rain day show that the error correlation and error standard deviation of LST and low-level atmospheric temperature and humidity are closely related to the weather background,and also have obvious diurnal variations.These results provide valuable information for strongly coupled land-atmosphere assimilation.
基金funded by the National Natural Science Foundation of China(52079103)the Outstanding Youth Science Fund of Xi'an University of Science and Technology(2024YQ2-02).
文摘The implementation of long-term shelterbelt programs in the middle reaches of the Yellow River(MRYR),China not only has improved the overall ecological environment,but also has led to the changes of land use pattern,causing carbon storage exchanges.However,the relationship between carbon storage and land use change in the MRYR is not concerned,which results in the uncertainty in the simulation of carbon storage in this area.Land use changes directly affect the carbon storage capacity of ecosystems,and as an indicator reflecting the overall state of land use,land use degree has an important relationship with carbon storage.In this study,land use data and the integrated valuation of ecosystem services and trade-offs(InVEST)model were used to assess the trends in land use degree and carbon storage in the MRYR during 1980-2020.The potential impact index and the standard deviation ellipse(SDE)algorithm were applied to quantify and analyze the characteristics of the impact of land use changes on carbon storage.Subsequently,land use transitions that led to carbon storage variations and their spatial variations were determined.The results showed that:(1)the most significant periods of carbon storage changes and land use transitions were observed during 1990-1995 and 1995-2020,with the most changed areas locating in the east of Fenhe River and in northwestern Henan Province;(2)the positive impact of land use degree on carbon storage may be related to the environmental protection measures implemented along the Yellow River,while the negative impact may be associated with the expansion of construction land in plain areas;and(3)the conversion of other land use types to grassland was the primary factor affecting carbon storage changes during 1980-2020.In future land use planning,attention should be given to the direction of grassland conversion,and focus on reasonably limiting the development of construction land.To enhance carbon storage,it will be crucial to increase the area of high-carbon-density land types,such as forest land and grassland under the condition that the area of permanent farmland does not decrease.
基金Supported by National Key Research and Development Program of China(Grant No.2024YFB3409800)Postdoctoral Fellowship Program of CPSF of China(Grant No.GZB20240940)China Postdoctoral Science Foundation(Grant Nos.2025T181108,2024M764127)。
文摘Reconstructing three-dimensional(3D)shapes from a single image remains a significant challenge in computer vision due to the inherent ambiguity caused by missing or occluded shape information.Previous studies have predominantly focused on mesh models supervised by multi-view silhouettes.However,such methods are limited in reconstructing fine details.In this study,a 3D mesh model is predicted from a single image,leveraging depth consistency and without requiring viewpoint pose annotations.The model effectively learns strong shape priors that preserve finer structures and accurately predicts view poses from"correlation-supervised"viewpoints.Additionally,standard deviation and Laplacian losses were employed to regulate mesh edge distribution,resulting in more precise reconstructions.Differentiable renderer functions were derived from the 3D mesh to generate depth maps.Compared to conventional approaches,the proposed method provided superior representation of subtle structures.When applied to both synthetic and real-world datasets,the model outperformed existing methods in view-based 3D reconstruction tasks.
文摘In patients with advanced cancer,the prevalence rate of cardiac autonomic neuropathy(CAN)is high,and the prognosis of patients with CAN is generally poor.Although mechanisms including inflammation,infection,metabolism,neurodegeneration,toxic processes,and cancer treatment have been proposed as etiologies of CAN in cancer patients,these mechanisms have not been completely elucidated,and their relationship has only been described indirectly.A study involving 127 cancer patients revealed that both the disease and its treatments can lead to a decrease in heart rate variability(HRV)indicating the autonomic imbalance.Because managing CAN is essential for improving the survival and quality of life of patients with cancer,patients and specialists can work together to customize cancer treatment and management using HRV as an index.
文摘Eight temperate deciduous tree species, Acer rubrum L., A. saccharinum L., A. saccharum Marsh., Belluta alleghaniensis Britton., Fraxinus nigra Marsh., Quercus rubra L., Titia americana L., and Ulmus americana L. in eastern North America, were selected to explore relationship between the northward distribution of temperate tree species and climatic factors. For each species, more than 30 sites at their north limits of distribution were obtained from their distribution maps, and 11 climatic indices at the north limits were computed. The standardized standard deviation (SD) method, which compares the magnitude of variance of climatic indices, was used to detect which climatic parameter was the most important for explaining northward distribution of these species. We presume that the climatic parameter that has the smallest variance at the north limit would be assigned as the dominant climatic factor for limiting the distribution of this species. The results derived from the standardized SD method indicated that the SD value of warmth index (WI) and/or annual biotemperature (ABT) were the smallest among the 11 climatic indices. Since both WI and ABT represent growing season temperature, it suggested that growing season temperature was the most important climatic factor for explaining the northward distribution of these temperate tree species. The relationships between several climatic indices, WI, coldness index (CI), annual precipitation (AP), annual range of temperature (ART) and humid/arid index were also analyzed. As a result, at the north limits of all these species, both WI and CI decreased with an increase of AP, and CI increased with an increase of ART. Besides growing season temperature, precipitation and climatic continentality also have influence on the northward distribution of the temperate trees in eastern North America.
基金sponsored by the 973 Program (No. 2009CB219505)the Talents Introduction Special Project of Guangdong Ocean University (No. 0812182)
文摘In order to study the scale characteristics of heterogeneities in complex media, a random medium is constructed using a statistical method and by changing model parameters （autocorrelation lengths a and b）, the scales of heterogeneous geologic bodies in the horizontal and the vertical Cartesian directions may be varied in the medium. The autocorrelation lengths a and b represent the mean scale of heterogeneous geologic bodies in the horizontal and vertical Cartesian directions in the randQm medium, respectively. Based on this model, the relationship between model autocorrelation lengths and heterogeneous geologic body scales is studied by horizontal velocity variation and standard deviation. The horizontal velocity variation research shows that velocities are in random perturbation. The heterogeneous geologic body scale increases with increasing autocorrelation length. The recursion equation for the relationship between autocorrelation lengths and heterogeneous geologic body scales is determined from the velocity standard deviation research and the actual heterogeneous geologic body scale magnitude can be estimated by the equation.
文摘Using conventional mathematical statistics,linear regression and the standard deviation,the quantitative analysis was made on the climate changes in Shenyang.The results showed that the trend of precipitation reduced 155 mm,which was made the greatest contribution by summer and autumn.It decreased 43 mm on the average after the climate jump.The precipitation variability in spring increased and drought risk in spring increased.The first soaking rain limited the spring planting time.The temperature trend raised 1.3℃,mainly in spring and winter.The frost-free period extended about 13 d.The accumulated temperature trends in crop growing season increased 290℃ and it had an average increase of 178℃ after the climate jump.This trend of climate warming made the end of last frost advanced.Early sowing of crops suitably was possible,which was beneficial for agricultural production.The precipitation decrease,the time delay and instability of the first soaking rain were unfavorable for crop growth and seeding.And they became the factors that constrained the normal growth and stabile yield raise of crops.
文摘Using GIS spatial statistical analysis method, with ArcGIS software as an analysis tool, taking the diseased maize in Hedong District of Linyi City as the study object, the distribution characteristic of the diseased crops this time in spatial location was analyzed. The results showed that the diseased crops mainly dis- tributed along with river tributaries and downstream of main rivers. The correlation between adjacent diseased plots was little, so the infection of pests and diseases were excluded, and the major reason of incidence might be river pollution.
文摘Based on slow- and fast-response measurements under neutral stratification conditions from a 325-m meteorological tower located in a built-up area of north-central Beijing as well as a descriptive survey of surface roughness elements (i.e., buildings and trees) around the tower site, urban roughness lengths, zo, with zero-plane displacement height are estimated using logarithmic wind profile and morphometric methods in eight 45° directional sectors. When comparing their results with each other, the slow-response method tends to give smaller zo values. At a given location, considerable directional variations in values are observed. The effect of surface roughness on urban turbulence characteristics in terms of non-dimensional standard deviations of three-component velocity, σi/u*1 (where i = u, v, w and u*1 is local friction velocity), is investigated.
基金funded by the 135 Strategic Program of the Institute of Mountain Hazards and Environment, CAS (Grant No. SDS135-1703)Coupled relationship and regulation mechanism between rural livelihoods and ecosystem services in the Three Gorges Reservoir Area (No.41371539)
文摘Changes of cultivated land patterns caused by major water conservation projects are rarely reported. We selected the Three Gorges Reservoir area in China to study the change in area and landscape pattern of the cultivated land in the head,central, and tail areas of the reservoir that took place between 1992 and 2015;we then studied the spatial distribution of the cultivated land in the three parts of the reservoir;finally, we studied the driving forces behind the changes in the cultivated land. The results derived are as follows.(1) During the construction of the Three Gorges Project(TGP, 1992–2015), the area of cultivated land around the reservoir decreased by30.23 million ha. This reduction occurred in phases:the most severe change in cultivated land occurred during the later stage of the project(2002–2010);only 0.62 million ha of cultivated land did not change between 1992 and 2015.(2) Spatial pattern analysis showed that the cultivated land in the three parts of the reservoir changed from a northern distribution to a southern distribution;thus, the area of cultivated land in the north decreased over the time period. The area of cultivated land in the head and tail areas decreased by varying degrees, while it increased in the central area over the 23 years, indicating that the change in cultivated land showed regional differences.(3) The TGP, the policy of reverting farmland to forest,and urbanization were the main driving factors for the change of cultivated land, but there were differences in their impacts at different stages.(4) According to the patch dynamics of the land cover change, the degree of change gradually intensified during the early and later stages of the project and then stabilized during the operational period. Our research provides scientific support for the protection of cultivated land resources and food security in the reservoir area and for the coordination of social and economic development, which is of great significance to sustainable development in the reservoir area.
基金funded by National Natural Science Foundation of China(31570627)Hunan Forestry Science and Technology Project(XLK201740)+1 种基金Hunan Science and Technology Innovation Platform and Talent Plan(2017TP1022)Hunan Science and Technology Plan Project(2015WK3017)。
文摘It is important to quantify and analyze forest spatial patterns for studying biological characteristics,population interaction and the relationship between the population and environment.In this study,the forest spatial structure unit was generated based on the Delaunay triangulation model(DTM),and the weights were generated using the comprehensive values of the tree diameter at breast height,total height and crown width.The distance between neighbors determined by the DTM was weighted to transform the original coordinates of trees into logical coordinates.Then,a weighted spatial pattern(WSP)was developed.After weighting,the neighboring trees were replaced,the replacement ratio was 38.3%,and there was 57.4%of the central tree.Correlation analysis showed that the uniform angle index of the WSP was significantly correlated with the tree size standard deviation under uniformity(r=0.932)and randomness(r=0.711).The DTM method not only considers the spatial distance between trees,but also considers the non-spatial attributes of trees.By changing the spatial topological relation between trees,this method further improves the spatial structure measurement of forest.
基金This research was supported by the Innovation Project of the Chinese Academy of Sciences （KZCX3-SW-339 and KZCX3-SW-329） the National Natural Science Foundation of China （Grant No. 40520140126）.
文摘Based on CAMP/Tibet [Coordinated Enhanced Observing Period （CEOP） Asia-Australia Monsoon Project （CAMP） on the Tibetan Plateau] turbulent data collected at the Bujiao （B J） site of the Nagqu area, the turbulent structure and transportation characteristics in the near surface layer during summer are analyzed. The main results show that the relationship between the normalized standard deviation of 3D wind speed and stability satisfies the similarity law under both unstable and stable stratifications. The relations of normalized standard deviation of temperature and specific humidity to stability only obey the ＂-1/3 power law＂ under unstable conditions. In the case of stable stratifications, their relations to stability are dispersing. The sensible heat dominates in the dry period, while in the wet period, the latent heat is larger than the sensible heat.
