Herbivorous ungulates are vital elements of forest ecosystems,yet their impact on tree regeneration and forest dynamics is challenging to assess.Despite their significant influence,few studies measure browsing pressur...Herbivorous ungulates are vital elements of forest ecosystems,yet their impact on tree regeneration and forest dynamics is challenging to assess.Despite their significant influence,few studies measure browsing pressure independently of precise ungulate population data.This study aimed to determine the regeneration mechanisms of palatable tree species in natural forest ecosystems by measuring the forage abundance from young trees of focal species and estimating the browsing pressure exerted by ungulates.We analyzed an extensive dataset of 2,838 tree saplings in two national parks in Poland to examine relationships between variables using a zero-intercept linear regression,and multiple linear regression models,and performed parametric and nonparametric tests.We found that the browsing intensity index(BI)is a good predictor of browsing pressure.Both total abundance and twig dry mass loss due to ungulate browsing were more pronounced in shorter saplings,with these effects decreasing as sapling height increased.Picea abies was the most abundant browse source in the Tatra National Park(TNP),whereas Fagus sylvatica dominated in the Roztocze National Park(RNP).Acer pseudoplatanus and Sorbus aucuparia experienced significantly higher browsing pressure in the TNP,whereas Carpinus betulus was more heavily browsed than other species in the RNP.The increase in browse abundance rapidly reduced ungulate browsing pressure on highly palatable tree species.We conclude that despite the high browsing pressure on the palatable species,the contribution of browse from focal species helps to mitigate this pressure and supports their regeneration in the forest canopy.Therefore,this finding provides valuable insights for managing and conserving tree species vulnerable to ungulate browsing in natural forest ecosystems.In addition,the method we used in this study is novel to estimate browsing pressure and assess the recruitment potential of vulnerable tree species;hence,it can be applied in large-scale studies with similar scenarios.展开更多
The effects of on-line solution, off-line solution and aging heat treatment on the microstructure and hardness of the die-cast AZ91D alloys were investigated. Brinell hardness of die-cast AZ91D alloy increases through...The effects of on-line solution, off-line solution and aging heat treatment on the microstructure and hardness of the die-cast AZ91D alloys were investigated. Brinell hardness of die-cast AZ91D alloy increases through on-line solution and off-line aging treatment but decreases after off-line solution treatment. By X-ray diffractometry, optical microscopy, differential thermal analysis, scanning electron microscopy and X-ray energy dispersive spectroscopy, it is found that the microstructures of the die-cast AZ91D magnesium alloy before and after on-line solution and off-line aging are similar, consisting of α-Mg and β-Al12Mg17. The precipitation of Al element is prevented by on-line solution so that the effect of solid solution strengthening is enhanced. The β-Al12Mg17 phases precipitate from supersaturated Mg solid solution after off-line aging treatment, and lead to microstructure refinement of AZ91D alloy, so the effect of precipitation hardening is enhanced. The β-Al12Mg17 phases dissolve in the substructure after off-line solution treatment, which leads to that the grain boundary strengthening phase is reduced significantly and the hardness of die cast AZ91D is reduced.展开更多
The IAP (Institute of Atmospheric Physics) land-surface model (IAP94) is described. This model is a comprehensive one with detailed description for the processes of vegetation, snow and soil. Particular attention has ...The IAP (Institute of Atmospheric Physics) land-surface model (IAP94) is described. This model is a comprehensive one with detailed description for the processes of vegetation, snow and soil. Particular attention has been paid to the cases with three water phases in the surface media. On the basis of the mixture theory and the theory of fluid dynamics of porous media, the system of universal conservational equations for water and heat of soil, snow and vegetation canopy has been constructed. On this background, all important factors that may affect the water and heat balance in media can be considered naturally, and each factor and term possess distinct physical meaning. In the computation of water content and temperature, the water phase change and the heat transportation by water flow are taken into account. Moreover, particular attention has been given to the water vapor diffusion in soil for arid or semi-arid cases, and snow compaction. In the treatment of surface turbulent fluxes, the difference between aerodynamic and thermal roughness is taken into account. The aerodynamic roughness of vegetation is calculated as a function of canopy density, height and zero-plane displacement. An extrapolation of log linear and exponential relationship is used when calculating the wind profile within canopy. The model has been validated against field measurements in off-line simulations. The desirable model′s performance leads to the conclusion that the IAP94 is able to reproduce the main physical mechanisms governing the energy and water balances in the global land surface. Part II of the present study will concern the validation in a 3-D experiment coupled with the IAP Two-Level AGCM.展开更多
Off-line programming （OLP） system becomes one of the most important programming modules for the robotic belt grinding process, however there lacks research on increasing the grinding dexterous space depending on the...Off-line programming （OLP） system becomes one of the most important programming modules for the robotic belt grinding process, however there lacks research on increasing the grinding dexterous space depending on the OLP system. A new type of grinding robot and a novel robotic belt grinding workcell are forwarded, and their features are briefly introduced. An open and object-oriented off-line programming system is developed for this robotic belt grinding system. The parameters of the trimmed surface are read from the initial graphics exchange specification （IGES） file of the CAD model of the workpiece. The deBoor-Cox basis function is used to sample the grinding target with local contact frame on the workpiece. The numerical formula of inverse kinematics is set up based on Newton＇s iterative procedure, to calculate the grinding robot configurations corresponding to the grinding targets. After the grinding path is obtained, the OLP system turns to be more effective than the teach-by-showing system. In order to improve the grinding workspace, an optimization algorithm for dynamic tool frame is proposed and performed on the special robotic belt grinding system. The initial tool frame and the interval of neighboring tool frames are defined as the preparation of the algorithm. An optimized tool local frame can be selected to grind the complex surface for a maximum dexterity index of the robot. Under the optimization algorithm, a simulation of grinding a vane is included and comparison of grinding workspace is done before and after the tool frame optimization. By the algorithm, the grinding workspace can be enlarged. Moreover the dynamic tool frame can be considered to add one degree-of-freedom to the grinding kinematical chain, which provides the theoretical support for the improvement of robotic dexterity for the complex surface grinding.展开更多
To support withdrawing and storing money from all levels of the bank for the customers in the real world, in this paper, we propose a proxy blind signature scheme and an off-line e-cash scheme based on the new proxy b...To support withdrawing and storing money from all levels of the bank for the customers in the real world, in this paper, we propose a proxy blind signature scheme and an off-line e-cash scheme based on the new proxy blind signature scheme. The pro- posed proxy blind signature is proven secure in the random oracle model under chosen-target computational Diffie-Hellman assump- tions, and the e-cash scheme can satisfy the security requirements of unforgeability, anonymity, and traceability.展开更多
Similarity matching and this paper, a saliency-based information presentation are two matching algorithm is proposed key factors in information retrieval. In for user-oriented search based on the psychological studies...Similarity matching and this paper, a saliency-based information presentation are two matching algorithm is proposed key factors in information retrieval. In for user-oriented search based on the psychological studies on human perception, and major emphasis on the saliently similar aspect of objects to be compared is placed and thus the search result is more agreeable for users. After relevant results are obtained, the cluster-based browsing algorithm is adopted for search result presentation based on social network analysis. By organizing the results in clustered lists, the user can have a general understanding of the whole collection by viewing only a small part of results and locate those of major interest rapidly. Experimental results demonstrate the advantages of the proposed algorithm over the traditional work.展开更多
In order to further understand the land surface processes over the northern Tibetan Plateau, this study produced an off-line simulated examination at the Bujiao site on the northern Tibetan Plateau from June 2002 to A...In order to further understand the land surface processes over the northern Tibetan Plateau, this study produced an off-line simulated examination at the Bujiao site on the northern Tibetan Plateau from June 2002 to April 2004, using the Noah Land Surface Model （Noah LSM） and observed data from the CAMP/Tibet experiment. The observed data were neces- sarily corrected and the number of soil layers in the Noah LSM was changed from 4 to 10 to enable this off-line simulation and analysis. The main conclusions are as follows： the Noah LSM performed well on the northern Tibetan Plateau. The simulated net radiation, upward longwave radiation, and upward shortwave radiation demonstrated the same remarkable annual and seasonal variation as the observed data, especially the upward longwave radiation. The simulated soil temperatures were acceptably close to the observed temperatures, especially in the shallow soil layers. The simulated freezing and melting processes were shown to start from the surface soil layer and spread down to the deep soil layers, but they took longer than the observed processes. However, Noah LSM did not adequately simulate the soil moisture. Therefore, additional high-quality, long-term observations of land surface-atmosphere processes over the Tibetan Plateau will be a key factor in proper adiustments of the model parameters in the future.展开更多
TongMai Granules is a Chinese medicine patent drug to treat cardiovascular diseases.It is prepared from the water extract of Dan-shen,Chuan-xiong and Ge-gen.The main compounds of TongMai Granules are isoflavone glycos...TongMai Granules is a Chinese medicine patent drug to treat cardiovascular diseases.It is prepared from the water extract of Dan-shen,Chuan-xiong and Ge-gen.The main compounds of TongMai Granules are isoflavone glycosides,isoflavones,and phenolic acids.However,it is difficult to detect low-polar compounds such as tanshinones and phthalides though they may also contribute to the therapeutic effect.In this work,an off-line two-dimensional chromatography method was developed to enrich the minor constituents in TongMai Granules.The extract was subjected to an SEP-PAK silica SPE column and eluted with petroleum ether,ethyl acetate–methanol(6:1,v/v),and methanol,successively.The three fractions were then analyzed using ultra-high performance liquid chromatography coupled with orbitrap mass spectrometry(UHPLC/orbitrap-MS).The isoflavones from Ge-gen,phenolic acids from Dan-shen and phthalides from Chuan-xiong were distributed in different fractions.A total of 131 compounds,including 59 from Ge-gen,26 from Dan-shen,43 from Chuan-xiong,and 3 common ones from Dan-shen and Chuan-xiong were tentatively identified.Among them,26 compounds were identified by comparing with reference standards.This study set a good example for comprehensive analysis of the constituents in traditional Chinese medicine formula.展开更多
Public Map Service Platforms(PMSPs)provide embedded map services in domains such as forests and rivers.Users from different domains(Domain Users)prefer specific spatial features,and extracting the Browsing Interests o...Public Map Service Platforms(PMSPs)provide embedded map services in domains such as forests and rivers.Users from different domains(Domain Users)prefer specific spatial features,and extracting the Browsing Interests of Domain Users(BIDUs)can help elucidate users’access intentions and provide suitable recommendations.Previous research has found that access frequency of spatial features is an indicator of users’browsing interests;however,highfrequency spatial features are sparsely distributed,resulting in inaccurate extraction of browsing interests.Our objective is to model the spatial co-occurrence of spatial features and employ BIDUs extraction to address this limitation.First,to extract spatial features in tiles,we proposed a k-nearest neighbor method for Point-of-Interest(POI)extraction and a template-based method for Land Uses/Land Covers extraction.Then,we developed the word2vec model to construct a POI semantic space to quantify spatial co-occurrence and employed multi-domain user classification to verify its effectiveness.Finally,a combined word2vec and singular value decomposition model is proposed to perform topic extraction as a representation of BIDUs.Compared with the baseline models,the proposed model integrates spatial co-occurrence from massive POIs to achieve high-accuracy BIDU extraction.Our findings can help construct domain user profiles and support the development of intelligent PMSPs.展开更多
The purpose of this study is to introduce the current applications of off-line programming technology in thermal spraying,including some popular methods of path generation,procedure simulation,robot kinematics optimiz...The purpose of this study is to introduce the current applications of off-line programming technology in thermal spraying,including some popular methods of path generation,procedure simulation,robot kinematics optimization,etc.Indeed this technology reduces the difficulty of robot programming and enormously improves its facility for thermal spraying.At the last part of this paper,presented two examples of off-line programming in thermal spraying which refer to trajectory optimization on a work piece with a great angle and path generation on the complex work piece.The simulations and experiments have proved that off-line programming can effectively improve the production efficiency and the quality of coating.展开更多
Segmentation of cursive text has been one of the major problems in Arabic writing. The problem is the shape of the letter which is context sensitive, depending on it’s location within a word. Many text recognition sy...Segmentation of cursive text has been one of the major problems in Arabic writing. The problem is the shape of the letter which is context sensitive, depending on it’s location within a word. Many text recognition systems recognize text imagery at the character level and assemble words from the recognized characters. Unfortunately this approach does not work with Arabic text. In this paper we describe a new approach to segment Arabic text imagery at a word level, without analyzing individual characters. This approach avoids the problem of individual characters segmentation, and can overcome local errors in character recognition.展开更多
A study of the interference simulation based on robot welding of the radar pedestal was carried out by using the KUKA Sim Pro simulation software and off-line program technology. Compared with the actual robot welding...A study of the interference simulation based on robot welding of the radar pedestal was carried out by using the KUKA Sim Pro simulation software and off-line program technology. Compared with the actual robot welding process, it was found that the trajectory of the simulated robot welding process in line with that recorded in the actual welding process, and the actual limit and interference appeared at the same place as the simulation process. There was no interference phenomenon on the outside weld-seam; on the internal weld-seam, especially on the weld-joint of support plate connected to the cylinder, a phenomenon of interference appeared. It was helpful to use the simulation method to guide the actual robot welding so as to protect robot from impacting and reduce the weld defects.展开更多
In 2010,Lee et al proposed two simple and efficient three-party password-authenticated key exchange protocols that had been proven secure in the random oracle model.They argued that the two protocols could resist offl...In 2010,Lee et al proposed two simple and efficient three-party password-authenticated key exchange protocols that had been proven secure in the random oracle model.They argued that the two protocols could resist offline dictionary attacks.Indeed,the provable approach did not provide protection against off-line dictionary attacks.This paper shows that the two protocols are vulnerable to off-line dictionary attacks in the presence of an inside attacker because of an authentication flaw.This study conducts a detailed analysis on the flaw in the protocols and also shows how to eliminate the security flaw.展开更多
Ungulate browsing often impairs tree regeneration,thus preventing the achievement of economic or conservation goals.Forest ungulate management would thus benefit from a practical decision tool that facilitates method ...Ungulate browsing often impairs tree regeneration,thus preventing the achievement of economic or conservation goals.Forest ungulate management would thus benefit from a practical decision tool that facilitates method selection from a wide range of monitoring methods and indicators currently available.In this study,we first provide an overview of the different browsing-impact monitoring methods and indicators currently applied.We then present a newly developed decision matrix for method evaluation that can assist forest stakeholders in choosing the browsing-impact monitoring method best suited to their needs,based on the selected indicators.The first step involved two separate literature reviews to create an overview of the currently applied methods and to select the indicators best suited for measuring browsing impact.Three types of indicator groups with their respective parameters were considered important for method evaluation:browsing indicators(e.g.regeneration density,browsing incidents),performance indicators(e.g.expense,expertise)and data quality indicators(e.g.susceptibility to measurement errors).Subsequently,all parameters defined within each indicator group were categorised and a grade was assigned to each category.To create the final method-indicator matrix,each browsing-impact monitoring method received a grade for each parameter within all indicator groups,reflecting the specific advantages and disadvantages of implementing the respective parameter within a specific method.The utility of the matrix in selecting the most suitable monitoring method was then demonstrated using the example of Germany's national parks.Based on the weights added to the method-indicator matrix,as defined by national park representatives,and considering local requirements the nearest-tree method was favoured over the other two methods.This newly developed matrix provides a more scientific objectification of ungulate browsing-impact measures and can be easily used by forest managers to address their own requirements,based on a consideration of the advantages and disadvantages of the included methods.展开更多
The passwords for unlocking the mobile devices are relatively simple,easier to be stolen,which causes serious potential security problems.An important research direction of identity authentication is to establish user...The passwords for unlocking the mobile devices are relatively simple,easier to be stolen,which causes serious potential security problems.An important research direction of identity authentication is to establish user behavior models to authenticate users.In this paper,a mobile terminal APP browsing behavioral authentication system architecture which synthesizes multiple factors is designed.This architecture is suitable for users using the mobile terminal APP in the daily life.The architecture includes data acquisition,data processing,feature extraction,and sub model training.We can use this architecture for continuous authentication when the user uses APP at the mobile terminal.展开更多
Thick walled curve welding are usually joined by multi-layer and multi-pass welding, which quality and efficiency could be improved by off-line programming of robot welding. However, the precision of off-line programm...Thick walled curve welding are usually joined by multi-layer and multi-pass welding, which quality and efficiency could be improved by off-line programming of robot welding. However, the precision of off-line programming welding path was decreased due to the deviation between the off-line planned welding path and the actual welding path. A path planning algorithm and a path compensation algorithm of multi-layer and multi-pass curve welding seam for off-line programming of robot welding are developed in this paper. Experimental results show that the robot off-line programming improves the welding efftcieney and precision for thick walled curve welding seam.展开更多
Fire is regarded as management practice for maintaining grasslands and savannas. The vegetation occurring in fire prone areas becomes highly adapted to fire occurrences in savannas and grasslands. However, documentati...Fire is regarded as management practice for maintaining grasslands and savannas. The vegetation occurring in fire prone areas becomes highly adapted to fire occurrences in savannas and grasslands. However, documentation on the influence of burning on vegetation is still limited in an albany thicket biome. The aim of the study was to evaluate the short-term influence of burning on species abundance, biomass production, wood plant density and browsing unit. Six plots (2500 m<sup>2</sup>) were demarcated;in each plot two parallel transects of 120 m<sup>2</sup> with 5 m distance apart were measured. Three plots were burned in spring season, while no burning was done on the other remaining plots. Forty points per plot were obtained using step-point method to determine the relative abundance at burned and unburned plots. Woody plants occurred within a transect were identified, counted and recorded to determine density and browsing unit. Three quadrats (<em>i.e</em>. 0.25 m<sup>2</sup>) per plot were randomly laid within the transect;aboveground plant material within a quadrat were harvested. A total of 18 samples were harvested and oven dried at 60<span style="white-space:nowrap;"><span style="white-space:nowrap;">˚</span></span>C for 48 hours to determine biomass production. The results showed that <em>Themeda triandra</em> (14%) and <em>Panicum maximum</em> (10%) were most abundant grass species at the burned plots. Burned plots had significantly higher biomass production (4804 kg/ha) compared to unburned plots (3641 kg/ha). <em>Vachellia karoo</em> (burned: 65.85% & unburn: 13.70%) and <em>Searsia pallens </em>(burned: 26.83% & unburned: 6.85%) were most dominant wood plant species at both burned and unburned plots. Burned plots had the highest browsing unit (3221 BU/ha) compared to unburned plots (2058 BU/ha). The decrease of woody plants at the burned plots proved that fire has a tremendous potential for managing woody plants. This study provided information on short-term influence of burning, however further long-term trials are required to determine the effects of burning.展开更多
Jojoba is a desert shrub,introduced in the marginal areas of Kenya during 1980s.Jojoba domestication is being faced by browsing problems due to pastoralism in these areas.Massive browsing of leaves lowers photosynthes...Jojoba is a desert shrub,introduced in the marginal areas of Kenya during 1980s.Jojoba domestication is being faced by browsing problems due to pastoralism in these areas.Massive browsing of leaves lowers photosynthesis leading to decline in plant functions.An experiment was set up in Maungu,with the aim of determining the effect of browsing on jojoba seedlings.The experimental design was a randomized complete block design with three treatments replicated three times.The treatments consisted of varying levels of browsing as follows:non browsed,50%browsed and fully browsed.Seedlings were raised for six months before sampling.Variables assessed were:survival,height,root-collar diameter,leaf size,root length and number,internode length,sprout number,root/shoot ratio and total biomass.ANOVA was performed to determine differences among the treatments whilst significant differences among the means were separated using least significant difference(LSD)at p≤0.05.Results showed fully browsed seedlings were significantly lower in height(26.2 cm),internode length(9.7 mm),leaf length(18.3 mm)and width(10.4 mm)and total fresh plant biomass(11.0 g)compared to the non browsed ones which showed 31.1 cm,23.2,36.1 and 16.6 mm and 17.8 g,respectively.On the other hand,fully browsed seedlings showed significantly higher root/shoot ratio.Seedling growth was negatively affected by severity of browsing which resulted in stunted growth.The study recommended that browsing of seedlings should be prevented since it hinders plant growth.展开更多
基金funded by Polish National Science Foundation(NCN)(grant No.2018/31/B/NZ8/02786,project title:“How do largescale disturbances influence the relationship between ungulate herbivory and natural regeneration in temperate forests?”)from the Ministry of Science and Higher Education of the Republic of Poland within the framework of statutory activities SUB/040011-D019/2020 of the Department of Forest Biodiversity,University of Agriculture in Krakow.
文摘Herbivorous ungulates are vital elements of forest ecosystems,yet their impact on tree regeneration and forest dynamics is challenging to assess.Despite their significant influence,few studies measure browsing pressure independently of precise ungulate population data.This study aimed to determine the regeneration mechanisms of palatable tree species in natural forest ecosystems by measuring the forage abundance from young trees of focal species and estimating the browsing pressure exerted by ungulates.We analyzed an extensive dataset of 2,838 tree saplings in two national parks in Poland to examine relationships between variables using a zero-intercept linear regression,and multiple linear regression models,and performed parametric and nonparametric tests.We found that the browsing intensity index(BI)is a good predictor of browsing pressure.Both total abundance and twig dry mass loss due to ungulate browsing were more pronounced in shorter saplings,with these effects decreasing as sapling height increased.Picea abies was the most abundant browse source in the Tatra National Park(TNP),whereas Fagus sylvatica dominated in the Roztocze National Park(RNP).Acer pseudoplatanus and Sorbus aucuparia experienced significantly higher browsing pressure in the TNP,whereas Carpinus betulus was more heavily browsed than other species in the RNP.The increase in browse abundance rapidly reduced ungulate browsing pressure on highly palatable tree species.We conclude that despite the high browsing pressure on the palatable species,the contribution of browse from focal species helps to mitigate this pressure and supports their regeneration in the forest canopy.Therefore,this finding provides valuable insights for managing and conserving tree species vulnerable to ungulate browsing in natural forest ecosystems.In addition,the method we used in this study is novel to estimate browsing pressure and assess the recruitment potential of vulnerable tree species;hence,it can be applied in large-scale studies with similar scenarios.
基金Projects (2011BAE22B01, 2011BAE22B06) supported by the National Key Technologies R&D Program During the 12th Five-Year Plan Period of ChinaProject (2010NC018) supported by the Innovation Fund of Inner Mongolia University of Science and Technology, China
文摘The effects of on-line solution, off-line solution and aging heat treatment on the microstructure and hardness of the die-cast AZ91D alloys were investigated. Brinell hardness of die-cast AZ91D alloy increases through on-line solution and off-line aging treatment but decreases after off-line solution treatment. By X-ray diffractometry, optical microscopy, differential thermal analysis, scanning electron microscopy and X-ray energy dispersive spectroscopy, it is found that the microstructures of the die-cast AZ91D magnesium alloy before and after on-line solution and off-line aging are similar, consisting of α-Mg and β-Al12Mg17. The precipitation of Al element is prevented by on-line solution so that the effect of solid solution strengthening is enhanced. The β-Al12Mg17 phases precipitate from supersaturated Mg solid solution after off-line aging treatment, and lead to microstructure refinement of AZ91D alloy, so the effect of precipitation hardening is enhanced. The β-Al12Mg17 phases dissolve in the substructure after off-line solution treatment, which leads to that the grain boundary strengthening phase is reduced significantly and the hardness of die cast AZ91D is reduced.
文摘The IAP (Institute of Atmospheric Physics) land-surface model (IAP94) is described. This model is a comprehensive one with detailed description for the processes of vegetation, snow and soil. Particular attention has been paid to the cases with three water phases in the surface media. On the basis of the mixture theory and the theory of fluid dynamics of porous media, the system of universal conservational equations for water and heat of soil, snow and vegetation canopy has been constructed. On this background, all important factors that may affect the water and heat balance in media can be considered naturally, and each factor and term possess distinct physical meaning. In the computation of water content and temperature, the water phase change and the heat transportation by water flow are taken into account. Moreover, particular attention has been given to the water vapor diffusion in soil for arid or semi-arid cases, and snow compaction. In the treatment of surface turbulent fluxes, the difference between aerodynamic and thermal roughness is taken into account. The aerodynamic roughness of vegetation is calculated as a function of canopy density, height and zero-plane displacement. An extrapolation of log linear and exponential relationship is used when calculating the wind profile within canopy. The model has been validated against field measurements in off-line simulations. The desirable model′s performance leads to the conclusion that the IAP94 is able to reproduce the main physical mechanisms governing the energy and water balances in the global land surface. Part II of the present study will concern the validation in a 3-D experiment coupled with the IAP Two-Level AGCM.
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2007AA04Z2443)State Key Laboratory for Man ufacturing Systems Engineering of Xi’an Jiaotong University of China
文摘Off-line programming （OLP） system becomes one of the most important programming modules for the robotic belt grinding process, however there lacks research on increasing the grinding dexterous space depending on the OLP system. A new type of grinding robot and a novel robotic belt grinding workcell are forwarded, and their features are briefly introduced. An open and object-oriented off-line programming system is developed for this robotic belt grinding system. The parameters of the trimmed surface are read from the initial graphics exchange specification （IGES） file of the CAD model of the workpiece. The deBoor-Cox basis function is used to sample the grinding target with local contact frame on the workpiece. The numerical formula of inverse kinematics is set up based on Newton＇s iterative procedure, to calculate the grinding robot configurations corresponding to the grinding targets. After the grinding path is obtained, the OLP system turns to be more effective than the teach-by-showing system. In order to improve the grinding workspace, an optimization algorithm for dynamic tool frame is proposed and performed on the special robotic belt grinding system. The initial tool frame and the interval of neighboring tool frames are defined as the preparation of the algorithm. An optimized tool local frame can be selected to grind the complex surface for a maximum dexterity index of the robot. Under the optimization algorithm, a simulation of grinding a vane is included and comparison of grinding workspace is done before and after the tool frame optimization. By the algorithm, the grinding workspace can be enlarged. Moreover the dynamic tool frame can be considered to add one degree-of-freedom to the grinding kinematical chain, which provides the theoretical support for the improvement of robotic dexterity for the complex surface grinding.
基金Supported by the National Natural Science Foundation of China(61272501)the National Key Basic Research Program(973Program)(2012CB315905)the Specialized Research Fund for the Doctoral Program of Higher Education(20091102110004)
文摘To support withdrawing and storing money from all levels of the bank for the customers in the real world, in this paper, we propose a proxy blind signature scheme and an off-line e-cash scheme based on the new proxy blind signature scheme. The pro- posed proxy blind signature is proven secure in the random oracle model under chosen-target computational Diffie-Hellman assump- tions, and the e-cash scheme can satisfy the security requirements of unforgeability, anonymity, and traceability.
基金Supported by the Fund for Basic Research of National Non-Profit Research Institutes(No.XK2012-2,ZD2012-7-2)the Fund for Preresearch Project of ISTIC(No.YY201208)
文摘Similarity matching and this paper, a saliency-based information presentation are two matching algorithm is proposed key factors in information retrieval. In for user-oriented search based on the psychological studies on human perception, and major emphasis on the saliently similar aspect of objects to be compared is placed and thus the search result is more agreeable for users. After relevant results are obtained, the cluster-based browsing algorithm is adopted for search result presentation based on social network analysis. By organizing the results in clustered lists, the user can have a general understanding of the whole collection by viewing only a small part of results and locate those of major interest rapidly. Experimental results demonstrate the advantages of the proposed algorithm over the traditional work.
基金the National Natural Science Foundation of China (Nos. 41075053 and 41275016)
文摘In order to further understand the land surface processes over the northern Tibetan Plateau, this study produced an off-line simulated examination at the Bujiao site on the northern Tibetan Plateau from June 2002 to April 2004, using the Noah Land Surface Model （Noah LSM） and observed data from the CAMP/Tibet experiment. The observed data were neces- sarily corrected and the number of soil layers in the Noah LSM was changed from 4 to 10 to enable this off-line simulation and analysis. The main conclusions are as follows： the Noah LSM performed well on the northern Tibetan Plateau. The simulated net radiation, upward longwave radiation, and upward shortwave radiation demonstrated the same remarkable annual and seasonal variation as the observed data, especially the upward longwave radiation. The simulated soil temperatures were acceptably close to the observed temperatures, especially in the shallow soil layers. The simulated freezing and melting processes were shown to start from the surface soil layer and spread down to the deep soil layers, but they took longer than the observed processes. However, Noah LSM did not adequately simulate the soil moisture. Therefore, additional high-quality, long-term observations of land surface-atmosphere processes over the Tibetan Plateau will be a key factor in proper adiustments of the model parameters in the future.
基金National Key Research and Development Program of China(Grant No.2018YFC1707301,2018YFC1707304)。
文摘TongMai Granules is a Chinese medicine patent drug to treat cardiovascular diseases.It is prepared from the water extract of Dan-shen,Chuan-xiong and Ge-gen.The main compounds of TongMai Granules are isoflavone glycosides,isoflavones,and phenolic acids.However,it is difficult to detect low-polar compounds such as tanshinones and phthalides though they may also contribute to the therapeutic effect.In this work,an off-line two-dimensional chromatography method was developed to enrich the minor constituents in TongMai Granules.The extract was subjected to an SEP-PAK silica SPE column and eluted with petroleum ether,ethyl acetate–methanol(6:1,v/v),and methanol,successively.The three fractions were then analyzed using ultra-high performance liquid chromatography coupled with orbitrap mass spectrometry(UHPLC/orbitrap-MS).The isoflavones from Ge-gen,phenolic acids from Dan-shen and phthalides from Chuan-xiong were distributed in different fractions.A total of 131 compounds,including 59 from Ge-gen,26 from Dan-shen,43 from Chuan-xiong,and 3 common ones from Dan-shen and Chuan-xiong were tentatively identified.Among them,26 compounds were identified by comparing with reference standards.This study set a good example for comprehensive analysis of the constituents in traditional Chinese medicine formula.
基金supported by the National Natural Science Foundation of China[grant numbers:U20A209141771426]Zhizhuo Research Fund on Spatial-Temporal Artificial Intelligence[grant number ZZJJ202204]LIESMARS Special Research Funding.
文摘Public Map Service Platforms(PMSPs)provide embedded map services in domains such as forests and rivers.Users from different domains(Domain Users)prefer specific spatial features,and extracting the Browsing Interests of Domain Users(BIDUs)can help elucidate users’access intentions and provide suitable recommendations.Previous research has found that access frequency of spatial features is an indicator of users’browsing interests;however,highfrequency spatial features are sparsely distributed,resulting in inaccurate extraction of browsing interests.Our objective is to model the spatial co-occurrence of spatial features and employ BIDUs extraction to address this limitation.First,to extract spatial features in tiles,we proposed a k-nearest neighbor method for Point-of-Interest(POI)extraction and a template-based method for Land Uses/Land Covers extraction.Then,we developed the word2vec model to construct a POI semantic space to quantify spatial co-occurrence and employed multi-domain user classification to verify its effectiveness.Finally,a combined word2vec and singular value decomposition model is proposed to perform topic extraction as a representation of BIDUs.Compared with the baseline models,the proposed model integrates spatial co-occurrence from massive POIs to achieve high-accuracy BIDU extraction.Our findings can help construct domain user profiles and support the development of intelligent PMSPs.
文摘The purpose of this study is to introduce the current applications of off-line programming technology in thermal spraying,including some popular methods of path generation,procedure simulation,robot kinematics optimization,etc.Indeed this technology reduces the difficulty of robot programming and enormously improves its facility for thermal spraying.At the last part of this paper,presented two examples of off-line programming in thermal spraying which refer to trajectory optimization on a work piece with a great angle and path generation on the complex work piece.The simulations and experiments have proved that off-line programming can effectively improve the production efficiency and the quality of coating.
文摘Segmentation of cursive text has been one of the major problems in Arabic writing. The problem is the shape of the letter which is context sensitive, depending on it’s location within a word. Many text recognition systems recognize text imagery at the character level and assemble words from the recognized characters. Unfortunately this approach does not work with Arabic text. In this paper we describe a new approach to segment Arabic text imagery at a word level, without analyzing individual characters. This approach avoids the problem of individual characters segmentation, and can overcome local errors in character recognition.
基金Funded by Anhui Provincial Natural Science Foundation of China(GFKJ2015B002)Quality Engineering Project of Anhui province(2014zy122)
文摘A study of the interference simulation based on robot welding of the radar pedestal was carried out by using the KUKA Sim Pro simulation software and off-line program technology. Compared with the actual robot welding process, it was found that the trajectory of the simulated robot welding process in line with that recorded in the actual welding process, and the actual limit and interference appeared at the same place as the simulation process. There was no interference phenomenon on the outside weld-seam; on the internal weld-seam, especially on the weld-joint of support plate connected to the cylinder, a phenomenon of interference appeared. It was helpful to use the simulation method to guide the actual robot welding so as to protect robot from impacting and reduce the weld defects.
基金Supported by the Natural Science Foundation of Jiangsu Province (Key Program) (BK2011023)
文摘In 2010,Lee et al proposed two simple and efficient three-party password-authenticated key exchange protocols that had been proven secure in the random oracle model.They argued that the two protocols could resist offline dictionary attacks.Indeed,the provable approach did not provide protection against off-line dictionary attacks.This paper shows that the two protocols are vulnerable to off-line dictionary attacks in the presence of an inside attacker because of an authentication flaw.This study conducts a detailed analysis on the flaw in the protocols and also shows how to eliminate the security flaw.
基金The present publication is a partial result of the R&D project‘Ungulate monitoring in German national parks’(FKZ:3518830200)which is supported by the Federal Agency for Nature Conservation(BfN).
文摘Ungulate browsing often impairs tree regeneration,thus preventing the achievement of economic or conservation goals.Forest ungulate management would thus benefit from a practical decision tool that facilitates method selection from a wide range of monitoring methods and indicators currently available.In this study,we first provide an overview of the different browsing-impact monitoring methods and indicators currently applied.We then present a newly developed decision matrix for method evaluation that can assist forest stakeholders in choosing the browsing-impact monitoring method best suited to their needs,based on the selected indicators.The first step involved two separate literature reviews to create an overview of the currently applied methods and to select the indicators best suited for measuring browsing impact.Three types of indicator groups with their respective parameters were considered important for method evaluation:browsing indicators(e.g.regeneration density,browsing incidents),performance indicators(e.g.expense,expertise)and data quality indicators(e.g.susceptibility to measurement errors).Subsequently,all parameters defined within each indicator group were categorised and a grade was assigned to each category.To create the final method-indicator matrix,each browsing-impact monitoring method received a grade for each parameter within all indicator groups,reflecting the specific advantages and disadvantages of implementing the respective parameter within a specific method.The utility of the matrix in selecting the most suitable monitoring method was then demonstrated using the example of Germany's national parks.Based on the weights added to the method-indicator matrix,as defined by national park representatives,and considering local requirements the nearest-tree method was favoured over the other two methods.This newly developed matrix provides a more scientific objectification of ungulate browsing-impact measures and can be easily used by forest managers to address their own requirements,based on a consideration of the advantages and disadvantages of the included methods.
基金partially supported by the National Key Research and Development Program of China(2018YFB2100801)。
文摘The passwords for unlocking the mobile devices are relatively simple,easier to be stolen,which causes serious potential security problems.An important research direction of identity authentication is to establish user behavior models to authenticate users.In this paper,a mobile terminal APP browsing behavioral authentication system architecture which synthesizes multiple factors is designed.This architecture is suitable for users using the mobile terminal APP in the daily life.The architecture includes data acquisition,data processing,feature extraction,and sub model training.We can use this architecture for continuous authentication when the user uses APP at the mobile terminal.
文摘Thick walled curve welding are usually joined by multi-layer and multi-pass welding, which quality and efficiency could be improved by off-line programming of robot welding. However, the precision of off-line programming welding path was decreased due to the deviation between the off-line planned welding path and the actual welding path. A path planning algorithm and a path compensation algorithm of multi-layer and multi-pass curve welding seam for off-line programming of robot welding are developed in this paper. Experimental results show that the robot off-line programming improves the welding efftcieney and precision for thick walled curve welding seam.
文摘Fire is regarded as management practice for maintaining grasslands and savannas. The vegetation occurring in fire prone areas becomes highly adapted to fire occurrences in savannas and grasslands. However, documentation on the influence of burning on vegetation is still limited in an albany thicket biome. The aim of the study was to evaluate the short-term influence of burning on species abundance, biomass production, wood plant density and browsing unit. Six plots (2500 m<sup>2</sup>) were demarcated;in each plot two parallel transects of 120 m<sup>2</sup> with 5 m distance apart were measured. Three plots were burned in spring season, while no burning was done on the other remaining plots. Forty points per plot were obtained using step-point method to determine the relative abundance at burned and unburned plots. Woody plants occurred within a transect were identified, counted and recorded to determine density and browsing unit. Three quadrats (<em>i.e</em>. 0.25 m<sup>2</sup>) per plot were randomly laid within the transect;aboveground plant material within a quadrat were harvested. A total of 18 samples were harvested and oven dried at 60<span style="white-space:nowrap;"><span style="white-space:nowrap;">˚</span></span>C for 48 hours to determine biomass production. The results showed that <em>Themeda triandra</em> (14%) and <em>Panicum maximum</em> (10%) were most abundant grass species at the burned plots. Burned plots had significantly higher biomass production (4804 kg/ha) compared to unburned plots (3641 kg/ha). <em>Vachellia karoo</em> (burned: 65.85% & unburn: 13.70%) and <em>Searsia pallens </em>(burned: 26.83% & unburned: 6.85%) were most dominant wood plant species at both burned and unburned plots. Burned plots had the highest browsing unit (3221 BU/ha) compared to unburned plots (2058 BU/ha). The decrease of woody plants at the burned plots proved that fire has a tremendous potential for managing woody plants. This study provided information on short-term influence of burning, however further long-term trials are required to determine the effects of burning.
文摘Jojoba is a desert shrub,introduced in the marginal areas of Kenya during 1980s.Jojoba domestication is being faced by browsing problems due to pastoralism in these areas.Massive browsing of leaves lowers photosynthesis leading to decline in plant functions.An experiment was set up in Maungu,with the aim of determining the effect of browsing on jojoba seedlings.The experimental design was a randomized complete block design with three treatments replicated three times.The treatments consisted of varying levels of browsing as follows:non browsed,50%browsed and fully browsed.Seedlings were raised for six months before sampling.Variables assessed were:survival,height,root-collar diameter,leaf size,root length and number,internode length,sprout number,root/shoot ratio and total biomass.ANOVA was performed to determine differences among the treatments whilst significant differences among the means were separated using least significant difference(LSD)at p≤0.05.Results showed fully browsed seedlings were significantly lower in height(26.2 cm),internode length(9.7 mm),leaf length(18.3 mm)and width(10.4 mm)and total fresh plant biomass(11.0 g)compared to the non browsed ones which showed 31.1 cm,23.2,36.1 and 16.6 mm and 17.8 g,respectively.On the other hand,fully browsed seedlings showed significantly higher root/shoot ratio.Seedling growth was negatively affected by severity of browsing which resulted in stunted growth.The study recommended that browsing of seedlings should be prevented since it hinders plant growth.
