The locator/ID separation paradigm has been widely discussed to resolve the serious scalability issue that today's Internet is facing. Many researches have been carried on with this issue to alleviate the routing ...The locator/ID separation paradigm has been widely discussed to resolve the serious scalability issue that today's Internet is facing. Many researches have been carried on with this issue to alleviate the routing burden of the Default Free Zone (DFZ), improve the traffic engineering capabilities and support efficient mobility and multi-homing. However, in the locator/ID split networks, a third party is needed to store the identifier-to-locator pairs. How to map identifiers onto locators in a scalable and secure way is a really critical challenge. In this paper, we propose SS-MAP, a scalable and secure locator/ID mapping scheme for future Internet. First, SS-MAP uses a near-optimal DHT to map identifiers onto locators, which is able to achieve the maximal performance of the system with reasonable maintenance overhead relatively. Second, SS-MAP uses a decentralized admission control system to protect the DHT-based identifier-to-locator mapping from Sybil attacks, where a malicious mapping server creates numerous fake identities (called Sybil identifiers) to control a large fraction of the mapping system. This is the first work to discuss the Sybil attack problem in identifier-to-locator mapping mechanisms with the best knowledge of the authors. We evaluate the performance of the proposed approach in terms of scalability and security. The analysis and simulation results show that the scheme is scalable for large size networks and can resistant to Sybil attacks.展开更多
Legacy IP address-based access control has met many challenges, because the network nodes cannot be identified accurately based on their variable IP addresses. “Locator/Identifier Split” has made it possible to buil...Legacy IP address-based access control has met many challenges, because the network nodes cannot be identified accurately based on their variable IP addresses. “Locator/Identifier Split” has made it possible to build a network access control mechanism based on the permanent identifier. With the support of “Locator/Identifier Split” routing and addressing concept, the Identifier-based Access Control (IBAC) makes net-work access control more accurate and efficient, and fits for mobile nodes’ access control quite well. Moreover, Self-verifying Identifier makes it possible for the receiver to verify the packet sender’s identity without the third part authentication, which greatly reduces the probability of “Identifier Spoofing”.展开更多
In the traditional Intemet Protocol （IP） architecture, there is an overload of IP sermntic problems. Existing solutions focused mainly on the infrastructure for the fixed network, and there is a lack of support for ...In the traditional Intemet Protocol （IP） architecture, there is an overload of IP sermntic problems. Existing solutions focused mainly on the infrastructure for the fixed network, and there is a lack of support for Mobile Ad Hoc Networks （MANETs）. To improve scalability, a routing protocol for MANETs is presented based on a locator named Tree-structure Locator Distance Vector （TLDV）. The hard core of this routing method is the identifier/locator split by the Distributed Hash Table （DHT） method, which provides a scalable routing service. The node locator indicates its relative location in the network and should be updated whenever topology changes, kocator space ks organized as a tree-structure, and the basic routing operation of the TLDV protocol is presented. TLDV protocol is compared to some classical routing protocols for MANETs on the NS2 platform Results show that TLDV has better scalability. Key words：展开更多
Current mobility management solutions based on ID/Locator separation are not easily deployed and cannot solve routing scalability and mobility problems. This paper proposes a novel network architecture based on ID/Loc...Current mobility management solutions based on ID/Locator separation are not easily deployed and cannot solve routing scalability and mobility problems. This paper proposes a novel network architecture based on ID/Locator separation and suggests a new mobility management solution. This solution solves the problem of scalability in the network and also provides better support for mobility. It can be easily deployed because no modification of the mobile host’s protocol stack is required. The identifier contains some routing information; so the solution provides intrinsic interworking with traditional mobile hosts. Because the mapping systems are distributed to the edge networks, robustness of the whole system is enhanced and handover delay is decreased.展开更多
The Thyristor-Controlled Series Compensator(TCSC)presents an effective solution for mitigating transmission congestion in power systems by regulating the distribution of line power flow.However,inherent faults within ...The Thyristor-Controlled Series Compensator(TCSC)presents an effective solution for mitigating transmission congestion in power systems by regulating the distribution of line power flow.However,inherent faults within the TCSC may lead to an unintended intensification of transmission congestion in other sections of the system post-installation,resulting in non-coherent phenomena of line blocking.In response to this challenge,this paper introduces a novel two-stage site selectionmethod for TCSC,emphasizing the enhancement of coherence in addressing line-blocking issues.Through rigorous non-coherent verification,this method mitigates the risk of line congestion deterioration due to TCSC faults.In the initial stage of the proposed method,TCSC faults are not considered during the extraction of system states.System state analysis is performed based on the TCSC site selection model,aiming to minimize system load reduction.The preliminary recommended installation position for TCSC is determined by sorting the frequency of TCSC installation occurrences on lines extracted from the analyzed system states.In the subsequent stage,accounting for the influence of TCSC faults on line faults,system operating states are extracted.Line and system congestion indices are calculated through the statistical analysis of the system state analysis results.The installation of TCSC at the preliminary position is scrutinized to identify non-coherent phenomena of line congestion on other lines.If such phenomena are observed,the installation position is excluded,and the TCSC site selection process is reinitiated based on the methodology from the first stage.To validate the effectiveness of the proposed method,a case study is conducted on a modified RBTS test system.The case study results indicate that,compared with TCSC siting schemes that do not consider transmission congestion non-coherency,the proposed non-coherency-based siting scheme reduces the system congestion expectation(SCE)and system congestion probability(SCP)by 17.7%and 11.4%,respectively,while lowering the LOLP and EENS by 2.56% and 4.55%,respectively.These results demonstrate that the proposed method can effectively alleviate transmission congestion and enhance the overall reliability of the system.展开更多
Cropland abandonment has been a widespread phenomenon in mountainous areas due to the increasing number of natural disasters and the massive migration of rural labor in the process of rapid urbanization.Land transfer ...Cropland abandonment has been a widespread phenomenon in mountainous areas due to the increasing number of natural disasters and the massive migration of rural labor in the process of rapid urbanization.Land transfer is a crucial prerequisite for ensuring food security and fostering rural revitalization.How to promote land transfer in mountainous areas remains a challenging but important task.Nevertheless,there is a dearth of research examining land transfers among farm households that specifically address mountainous regions,and the influence of grassroots governance and geographic location has not been thoroughly elucidated within this particular context.Based on 895household samples collected in Dabie Mountainous Area in China,this study employs binary and ordinal logistic regression models to provide a more comprehensive analysis on land transfers among rural households and the determinants,including the decision to transfer land,the existence of land transfer rents,the channel of land transfer,the duration of the transfer,the pre-transfer cultivation situation,and the level of satisfaction with the land transfer rent.The findings reveal that grassroots governance,geographic location,livelihood capital,and demographic factors significantly influence land transfers among rural households.Specifically,villagers'public participation positively affects land transfer participation(β=0.235,p<0.05),while the operation of village rules and regulations negatively impacts it(β=-0.296,p<0.05).Village cadre satisfaction positively influences both land transfer rent(β=0.274,p<0.05)and rent satisfaction(β=0.303,p<0.05).Improved civil relations in the village correlate with lower land transfer rent(β=-0.511,p<0.05),while a better social atmosphere is associated with higher satisfaction with transfer rent(β=0.575,p<0.01).Households at higher elevations tend to prefer government-mediated land transfers with longer durations.The distances to the township and county centers have contrasting effects on land transfer rent,but their impacts on participation in land transfer,choice of transfer channel,and duration are consistent.The study also found that different types of livelihood capital,as well as the demographic characteristics of households,significantly affect various aspects of land transfer.These empirical findings can inform policymaking to promote more efficient land transfers in mountainous region.展开更多
Gauss radial basis functions(GRBF)are frequently employed in data fitting and machine learning.Their linear independence property can theoretically guarantee the avoidance of data redundancy.In this paper,one of the m...Gauss radial basis functions(GRBF)are frequently employed in data fitting and machine learning.Their linear independence property can theoretically guarantee the avoidance of data redundancy.In this paper,one of the main contributions is proving this property using linear algebra instead of profound knowledge.This makes it easy to read and understand this fundamental fact.The proof of linear independence of a set of Gauss functions relies on the constructing method for one-dimensional space and on the deducing method for higher dimensions.Additionally,under the condition of preserving the same moments between the original function and interpolating function,both the interpolating existence and uniqueness are proven for GRBF in one-dimensional space.The final work demonstrates the application of the GRBF method to locate lunar olivine.By combining preprocessed data using GRBF with the removing envelope curve method,a program is created to find the position of lunar olivine based on spectrum data,and the numerical experiment shows that it is an effective scheme.展开更多
Development and implementation of pilgrims (Hajj) Guide application to be used at Hajj season would facilitate follow-up of campaign supervisors on their campaign’s safety and location. The systems would also allow H...Development and implementation of pilgrims (Hajj) Guide application to be used at Hajj season would facilitate follow-up of campaign supervisors on their campaign’s safety and location. The systems would also allow Hajj and Umrah administration to manage the crowd of the campaigns in an easy manner. In this paper, we propose Android/iPhone application that allows Hajj administration to monitor pilgrims using Quick Response Codes. Using quick response code application allows campaign supervisors and Hajj and Umrah employees to monitor pilgrims and guide them in case of getting lost. The application offers an easier and faster service than traditional approach used at Hajj season by human guidance. It is a very convenient service that would relief stresses of pilgrim’s relatives who worry about their relatives performing Hajj. The results show that the average score of our approach (QR) is 4.72 out of 5 comparing with traditional mobile applications indicating that the users are feeling enjoyable while using the new application features and the system is easy to use. Finally, the systems would assist in achieving the highest degree of pilgrims safety at Hajj season.展开更多
With the widespread deployment of assembly robots in smart manufacturing,efficiently offloading tasks and allocating resources in highly dynamic industrial environments has become a critical challenge for Mobile Edge ...With the widespread deployment of assembly robots in smart manufacturing,efficiently offloading tasks and allocating resources in highly dynamic industrial environments has become a critical challenge for Mobile Edge Computing(MEC).To address this challenge,this paper constructs a cloud-edge-end collaborative MEC system that enables assembly robots to offload complex workflow tasks via multiple paths(horizontal,vertical,and hybrid collaboration).Tomitigate uncertainties arising frommobility,the location predictionmodule is employed.This enables proactive channel-quality estimation,providing forward-looking insights for offloading decisions.Furthermore,we propose a fairness-aware joint optimization framework.Utilizing an improved Multi-Agent Deep Reinforcement Learning(MADRL)algorithm whose reward function incorporates total system cost,positional reliability,and timeout penalties,the framework aims to balance resource distribution among assembly robots while maximizing system utility.Simulation results demonstrate that the proposed framework outperforms traditional offloading strategies.By integrating predictive mobility management with fairness-aware optimization,the framework offers a robust solution for dynamic industrial MEC environments.展开更多
The diversion effect caused by the linked structure in a metro tunnel with cross-passage complicates the impact of longitudinal fire source location on the smoke backflow layering behavior that has not been clarified,...The diversion effect caused by the linked structure in a metro tunnel with cross-passage complicates the impact of longitudinal fire source location on the smoke backflow layering behavior that has not been clarified,despite the fact that the scenario exists in practice.A series of laboratory-scale experiments were conducted in this study to investigate the smoke back-layering length in a model tunnel with cross-passage.The heat release rate,the velocity of longitudinal air flow,and the location of the fire source were all varied.It was found that the behavior of smoke backflow for the fire source located at the upstream of bifurcation point resembles a single-hole tunnel fire.As the fire source’s position shifts downstream from the bifurcation point,the length of smoke back-layering progressively increases.A competitive interaction exists between airflow diversion and smoke diversion during smoke backflow,significantly affecting the smoke back-layering length in the main tunnel.The dimensionless smoke back-layering length model was formulated in a tunnel featuring a cross-passage,taking into account the positions of longitudinal fire sources.The dimensionless smoke back-layering length exhibits a positive correlation with the 17/18 power of total heat release rate Q and a negative correlation with the 5/2 power of longitudinal ventilation velocity V.展开更多
With the popularization of smart devices,Location-Based Services(LBS)greatly facilitates users’life,but at the same time brings the risk of users’location privacy leakage.Existing location privacy protection methods...With the popularization of smart devices,Location-Based Services(LBS)greatly facilitates users’life,but at the same time brings the risk of users’location privacy leakage.Existing location privacy protection methods are deficient,failing to reasonably allocate the privacy budget for non-outlier location points and ignoring the critical location information that may be contained in the outlier points,leading to decreased data availability and privacy exposure problems.To address these problems,this paper proposes a Mix Location Privacy Preservation Method Based on Differential Privacy with Clustering(MLDP).The method first utilizes the DBSCAN clustering algorithm to classify location points into non-outliers and outliers.For non-outliers,the scoring function is designed by combining geographic information and semantic information,and the privacy budget is allocated according to the heat intensity of the hotspot area;for outliers,the scoring function is constructed to allocate the privacy budget based on their correlation with the hotspot area.By comprehensively considering the geographic information,semantic information,and correlation with hotspot areas of the location points,a reasonable privacy budget is assigned to each location point,andfinallynoise is added throughthe Laplacemechanismto realizeprivacyprotection.Experimental results on tworeal trajectory datasets,Geolife and T-Drive,show that the MLDP approach significantly improves data availability while effectively protecting location privacy.Compared with the comparison methods,the maximum available data ratio of MLDP is 1.Moreover,compared with the RandomNoise method,its execution time is 0.056–0.061 s longer,and the logRE is 0.12951–0.62194 lower;compared with KemeansDP,QTK-DP,DPK-F,IDP-SC,and DPK-Means-up methods,it saves 0.114–0.296 s in execution time,and the logRE is 0.01112–0.38283 lower.展开更多
基金supported in part by National Key Basic Research Program of China (973 program) under Grant No.2007CB307101,2007CB307106National Key Technology R&D Program under Grant No.2008BAH37B03+2 种基金Program of Introducing Talents of Discipline to Universities (111 Project) under Grant No. B08002National Natural Science Foundation of China under Grant No.60833002China Fundamental Research Funds for the Central Universities under Grant No.2009YJS016
文摘The locator/ID separation paradigm has been widely discussed to resolve the serious scalability issue that today's Internet is facing. Many researches have been carried on with this issue to alleviate the routing burden of the Default Free Zone (DFZ), improve the traffic engineering capabilities and support efficient mobility and multi-homing. However, in the locator/ID split networks, a third party is needed to store the identifier-to-locator pairs. How to map identifiers onto locators in a scalable and secure way is a really critical challenge. In this paper, we propose SS-MAP, a scalable and secure locator/ID mapping scheme for future Internet. First, SS-MAP uses a near-optimal DHT to map identifiers onto locators, which is able to achieve the maximal performance of the system with reasonable maintenance overhead relatively. Second, SS-MAP uses a decentralized admission control system to protect the DHT-based identifier-to-locator mapping from Sybil attacks, where a malicious mapping server creates numerous fake identities (called Sybil identifiers) to control a large fraction of the mapping system. This is the first work to discuss the Sybil attack problem in identifier-to-locator mapping mechanisms with the best knowledge of the authors. We evaluate the performance of the proposed approach in terms of scalability and security. The analysis and simulation results show that the scheme is scalable for large size networks and can resistant to Sybil attacks.
文摘Legacy IP address-based access control has met many challenges, because the network nodes cannot be identified accurately based on their variable IP addresses. “Locator/Identifier Split” has made it possible to build a network access control mechanism based on the permanent identifier. With the support of “Locator/Identifier Split” routing and addressing concept, the Identifier-based Access Control (IBAC) makes net-work access control more accurate and efficient, and fits for mobile nodes’ access control quite well. Moreover, Self-verifying Identifier makes it possible for the receiver to verify the packet sender’s identity without the third part authentication, which greatly reduces the probability of “Identifier Spoofing”.
基金Acknowledgements This work was supported by the Hi-Tech Research and Development Program of China under Grant No.2007AA01Z407 the Co-Funding Project of Beijing Municipal education Commission under Grant No.JD100060630+3 种基金 National Foundation Research Project the National Natural Science Foundation Project under Grant No. 61170295 the Project of Aeronautical Science Foundation of China under Caant No.2011ZC51024 and the Fundamental Research Funds for the Central Universities.
文摘In the traditional Intemet Protocol （IP） architecture, there is an overload of IP sermntic problems. Existing solutions focused mainly on the infrastructure for the fixed network, and there is a lack of support for Mobile Ad Hoc Networks （MANETs）. To improve scalability, a routing protocol for MANETs is presented based on a locator named Tree-structure Locator Distance Vector （TLDV）. The hard core of this routing method is the identifier/locator split by the Distributed Hash Table （DHT） method, which provides a scalable routing service. The node locator indicates its relative location in the network and should be updated whenever topology changes, kocator space ks organized as a tree-structure, and the basic routing operation of the TLDV protocol is presented. TLDV protocol is compared to some classical routing protocols for MANETs on the NS2 platform Results show that TLDV has better scalability. Key words：
基金funded by the European Commission funded ICT-FP7 IP Project EFIPSANS under Grant No. INFSO-ICT-215549the National Basic Research Program of China ("973"Program) under Grant No. 2009CB320504
文摘Current mobility management solutions based on ID/Locator separation are not easily deployed and cannot solve routing scalability and mobility problems. This paper proposes a novel network architecture based on ID/Locator separation and suggests a new mobility management solution. This solution solves the problem of scalability in the network and also provides better support for mobility. It can be easily deployed because no modification of the mobile host’s protocol stack is required. The identifier contains some routing information; so the solution provides intrinsic interworking with traditional mobile hosts. Because the mapping systems are distributed to the edge networks, robustness of the whole system is enhanced and handover delay is decreased.
基金supported by Graduate Research and Innovation Program Project of Nanjing Institute of Technology(No.TB202517078).
文摘The Thyristor-Controlled Series Compensator(TCSC)presents an effective solution for mitigating transmission congestion in power systems by regulating the distribution of line power flow.However,inherent faults within the TCSC may lead to an unintended intensification of transmission congestion in other sections of the system post-installation,resulting in non-coherent phenomena of line blocking.In response to this challenge,this paper introduces a novel two-stage site selectionmethod for TCSC,emphasizing the enhancement of coherence in addressing line-blocking issues.Through rigorous non-coherent verification,this method mitigates the risk of line congestion deterioration due to TCSC faults.In the initial stage of the proposed method,TCSC faults are not considered during the extraction of system states.System state analysis is performed based on the TCSC site selection model,aiming to minimize system load reduction.The preliminary recommended installation position for TCSC is determined by sorting the frequency of TCSC installation occurrences on lines extracted from the analyzed system states.In the subsequent stage,accounting for the influence of TCSC faults on line faults,system operating states are extracted.Line and system congestion indices are calculated through the statistical analysis of the system state analysis results.The installation of TCSC at the preliminary position is scrutinized to identify non-coherent phenomena of line congestion on other lines.If such phenomena are observed,the installation position is excluded,and the TCSC site selection process is reinitiated based on the methodology from the first stage.To validate the effectiveness of the proposed method,a case study is conducted on a modified RBTS test system.The case study results indicate that,compared with TCSC siting schemes that do not consider transmission congestion non-coherency,the proposed non-coherency-based siting scheme reduces the system congestion expectation(SCE)and system congestion probability(SCP)by 17.7%and 11.4%,respectively,while lowering the LOLP and EENS by 2.56% and 4.55%,respectively.These results demonstrate that the proposed method can effectively alleviate transmission congestion and enhance the overall reliability of the system.
基金supported by the National Natural Science Foundation of China(Grant Nos.42371315,41901213)the Humanities and Social Sciences General Research Program of the Ministry of Education(Grant No.23YJC790141)。
文摘Cropland abandonment has been a widespread phenomenon in mountainous areas due to the increasing number of natural disasters and the massive migration of rural labor in the process of rapid urbanization.Land transfer is a crucial prerequisite for ensuring food security and fostering rural revitalization.How to promote land transfer in mountainous areas remains a challenging but important task.Nevertheless,there is a dearth of research examining land transfers among farm households that specifically address mountainous regions,and the influence of grassroots governance and geographic location has not been thoroughly elucidated within this particular context.Based on 895household samples collected in Dabie Mountainous Area in China,this study employs binary and ordinal logistic regression models to provide a more comprehensive analysis on land transfers among rural households and the determinants,including the decision to transfer land,the existence of land transfer rents,the channel of land transfer,the duration of the transfer,the pre-transfer cultivation situation,and the level of satisfaction with the land transfer rent.The findings reveal that grassroots governance,geographic location,livelihood capital,and demographic factors significantly influence land transfers among rural households.Specifically,villagers'public participation positively affects land transfer participation(β=0.235,p<0.05),while the operation of village rules and regulations negatively impacts it(β=-0.296,p<0.05).Village cadre satisfaction positively influences both land transfer rent(β=0.274,p<0.05)and rent satisfaction(β=0.303,p<0.05).Improved civil relations in the village correlate with lower land transfer rent(β=-0.511,p<0.05),while a better social atmosphere is associated with higher satisfaction with transfer rent(β=0.575,p<0.01).Households at higher elevations tend to prefer government-mediated land transfers with longer durations.The distances to the township and county centers have contrasting effects on land transfer rent,but their impacts on participation in land transfer,choice of transfer channel,and duration are consistent.The study also found that different types of livelihood capital,as well as the demographic characteristics of households,significantly affect various aspects of land transfer.These empirical findings can inform policymaking to promote more efficient land transfers in mountainous region.
基金Supported by the National Basic Research Program of China(2012CB025904)Zhengzhou Shengda University of Economics,Business and Management(SD-YB2025085)。
文摘Gauss radial basis functions(GRBF)are frequently employed in data fitting and machine learning.Their linear independence property can theoretically guarantee the avoidance of data redundancy.In this paper,one of the main contributions is proving this property using linear algebra instead of profound knowledge.This makes it easy to read and understand this fundamental fact.The proof of linear independence of a set of Gauss functions relies on the constructing method for one-dimensional space and on the deducing method for higher dimensions.Additionally,under the condition of preserving the same moments between the original function and interpolating function,both the interpolating existence and uniqueness are proven for GRBF in one-dimensional space.The final work demonstrates the application of the GRBF method to locate lunar olivine.By combining preprocessed data using GRBF with the removing envelope curve method,a program is created to find the position of lunar olivine based on spectrum data,and the numerical experiment shows that it is an effective scheme.
文摘Development and implementation of pilgrims (Hajj) Guide application to be used at Hajj season would facilitate follow-up of campaign supervisors on their campaign’s safety and location. The systems would also allow Hajj and Umrah administration to manage the crowd of the campaigns in an easy manner. In this paper, we propose Android/iPhone application that allows Hajj administration to monitor pilgrims using Quick Response Codes. Using quick response code application allows campaign supervisors and Hajj and Umrah employees to monitor pilgrims and guide them in case of getting lost. The application offers an easier and faster service than traditional approach used at Hajj season by human guidance. It is a very convenient service that would relief stresses of pilgrim’s relatives who worry about their relatives performing Hajj. The results show that the average score of our approach (QR) is 4.72 out of 5 comparing with traditional mobile applications indicating that the users are feeling enjoyable while using the new application features and the system is easy to use. Finally, the systems would assist in achieving the highest degree of pilgrims safety at Hajj season.
基金supported by the National Key R&D Program of China under Grant Nos.2024YFD2400200 and 2024YFD2400204supported in part by the Science and Technology Development Program for the Two Zones under Grant No.2023LQ02004.
文摘With the widespread deployment of assembly robots in smart manufacturing,efficiently offloading tasks and allocating resources in highly dynamic industrial environments has become a critical challenge for Mobile Edge Computing(MEC).To address this challenge,this paper constructs a cloud-edge-end collaborative MEC system that enables assembly robots to offload complex workflow tasks via multiple paths(horizontal,vertical,and hybrid collaboration).Tomitigate uncertainties arising frommobility,the location predictionmodule is employed.This enables proactive channel-quality estimation,providing forward-looking insights for offloading decisions.Furthermore,we propose a fairness-aware joint optimization framework.Utilizing an improved Multi-Agent Deep Reinforcement Learning(MADRL)algorithm whose reward function incorporates total system cost,positional reliability,and timeout penalties,the framework aims to balance resource distribution among assembly robots while maximizing system utility.Simulation results demonstrate that the proposed framework outperforms traditional offloading strategies.By integrating predictive mobility management with fairness-aware optimization,the framework offers a robust solution for dynamic industrial MEC environments.
基金funded by the National Natural Science Foundation of China(NSFC)under Grant No.52278415the National Key Research and Development Program of China under Grant No.2022YFC3801104+2 种基金Hebei Provincial Department of Education Project under Grant No.QN2025304the Innovation Fund Project of Hebei University of Engineering under Grant No.SJ2401002066the Sichuan Science and Technology Program under Grant No.2023YFS0407。
文摘The diversion effect caused by the linked structure in a metro tunnel with cross-passage complicates the impact of longitudinal fire source location on the smoke backflow layering behavior that has not been clarified,despite the fact that the scenario exists in practice.A series of laboratory-scale experiments were conducted in this study to investigate the smoke back-layering length in a model tunnel with cross-passage.The heat release rate,the velocity of longitudinal air flow,and the location of the fire source were all varied.It was found that the behavior of smoke backflow for the fire source located at the upstream of bifurcation point resembles a single-hole tunnel fire.As the fire source’s position shifts downstream from the bifurcation point,the length of smoke back-layering progressively increases.A competitive interaction exists between airflow diversion and smoke diversion during smoke backflow,significantly affecting the smoke back-layering length in the main tunnel.The dimensionless smoke back-layering length model was formulated in a tunnel featuring a cross-passage,taking into account the positions of longitudinal fire sources.The dimensionless smoke back-layering length exhibits a positive correlation with the 17/18 power of total heat release rate Q and a negative correlation with the 5/2 power of longitudinal ventilation velocity V.
基金supported in part by the National Natural Science Foundation of China(Grant No.61971291)the Basic Scientific Research Project of the Liaoning Provincial Department of Education(LJ212410144013)+2 种基金the Leading Talent of the‘Xing Liao Ying Cai Plan’(XLYC2202013)the Shenyang Natural Science Foundation(22-315-6-10)the Guangxuan Scholar of Shenyang Ligong University(SYLUGXXZ202205).
文摘With the popularization of smart devices,Location-Based Services(LBS)greatly facilitates users’life,but at the same time brings the risk of users’location privacy leakage.Existing location privacy protection methods are deficient,failing to reasonably allocate the privacy budget for non-outlier location points and ignoring the critical location information that may be contained in the outlier points,leading to decreased data availability and privacy exposure problems.To address these problems,this paper proposes a Mix Location Privacy Preservation Method Based on Differential Privacy with Clustering(MLDP).The method first utilizes the DBSCAN clustering algorithm to classify location points into non-outliers and outliers.For non-outliers,the scoring function is designed by combining geographic information and semantic information,and the privacy budget is allocated according to the heat intensity of the hotspot area;for outliers,the scoring function is constructed to allocate the privacy budget based on their correlation with the hotspot area.By comprehensively considering the geographic information,semantic information,and correlation with hotspot areas of the location points,a reasonable privacy budget is assigned to each location point,andfinallynoise is added throughthe Laplacemechanismto realizeprivacyprotection.Experimental results on tworeal trajectory datasets,Geolife and T-Drive,show that the MLDP approach significantly improves data availability while effectively protecting location privacy.Compared with the comparison methods,the maximum available data ratio of MLDP is 1.Moreover,compared with the RandomNoise method,its execution time is 0.056–0.061 s longer,and the logRE is 0.12951–0.62194 lower;compared with KemeansDP,QTK-DP,DPK-F,IDP-SC,and DPK-Means-up methods,it saves 0.114–0.296 s in execution time,and the logRE is 0.01112–0.38283 lower.
