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Hybrid Approach for Cost Efficient Application Placement in Fog-Cloud Computing Environments
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作者 Abdulelah Alwabel Chinmaya Kumar Swain 《Computers, Materials & Continua》 SCIE EI 2024年第6期4127-4148,共22页
Fog computing has recently developed as a new paradigm with the aim of addressing time-sensitive applications better than with cloud computing by placing and processing tasks in close proximity to the data sources.How... Fog computing has recently developed as a new paradigm with the aim of addressing time-sensitive applications better than with cloud computing by placing and processing tasks in close proximity to the data sources.However,the majority of the fog nodes in this environment are geographically scattered with resources that are limited in terms of capabilities compared to cloud nodes,thus making the application placement problem more complex than that in cloud computing.An approach for cost-efficient application placement in fog-cloud computing environments that combines the benefits of both fog and cloud computing to optimize the placement of applications and services while minimizing costs.This approach is particularly relevant in scenarios where latency,resource constraints,and cost considerations are crucial factors for the deployment of applications.In this study,we propose a hybrid approach that combines a genetic algorithm(GA)with the Flamingo Search Algorithm(FSA)to place application modules while minimizing cost.We consider four cost-types for application deployment:Computation,communication,energy consumption,and violations.The proposed hybrid approach is called GA-FSA and is designed to place the application modules considering the deadline of the application and deploy them appropriately to fog or cloud nodes to curtail the overall cost of the system.An extensive simulation is conducted to assess the performance of the proposed approach compared to other state-of-the-art approaches.The results demonstrate that GA-FSA approach is superior to the other approaches with respect to task guarantee ratio(TGR)and total cost. 展开更多
关键词 placement mechanism application module placement fog computing cloud computing genetic algorithm flamingo search algorithm
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Layered Coded Cache Placement and Cooperative Delivery with Sharing Links in Satellite-Terrestrial Integrated Networks
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作者 Gu Shushi Chen Zihan +2 位作者 Wu Yaonan Zhang Qinyu Wang Ye 《China Communications》 SCIE CSCD 2024年第3期217-229,共13页
Cooperative utilization of multidimensional resources including cache, power and spectrum in satellite-terrestrial integrated networks(STINs) can provide a feasible approach for massive streaming media content deliver... Cooperative utilization of multidimensional resources including cache, power and spectrum in satellite-terrestrial integrated networks(STINs) can provide a feasible approach for massive streaming media content delivery over the seamless global coverage area. However, the on-board supportable resources of a single satellite are extremely limited and lack of interaction with others. In this paper, we design a network model with two-layered cache deployment, i.e., satellite layer and ground base station layer, and two types of sharing links, i.e., terrestrial-satellite sharing(TSS) links and inter-satellite sharing(ISS) links, to enhance the capability of cooperative delivery over STINs. Thus, we use rateless codes for the content divided-packet transmission, and derive the total energy efficiency(EE) in the whole transmission procedure, which is defined as the ratio of traffic offloading and energy consumption. We formulate two optimization problems about maximizing EE in different sharing scenarios(only TSS and TSS-ISS),and propose two optimized algorithms to obtain the optimal content placement matrixes, respectively.Simulation results demonstrate that, enabling sharing links with optimized cache placement have more than 2 times improvement of EE performance than other traditional placement schemes. Particularly, TSS-ISS schemes have the higher EE performance than only TSS schemes under the conditions of enough number of satellites and smaller inter-satellite distances. 展开更多
关键词 coded content placement cooperative delivery energy efficiency sharing links STINs
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Efficient placement technology of proppants based on structural stabilizers
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作者 GUO Jianchun REN Shan +3 位作者 ZHANG Shaobin DIAO Su LU Yang ZHANG Tao 《Petroleum Exploration and Development》 SCIE 2024年第3期706-714,共9页
Fiber is highly escapable in conventional slickwater,making it difficult to form fiber-proppant agglomerate with proppant and exhibit limited effectiveness.To solve these problems,a novel structure stabilizer(SS)is de... Fiber is highly escapable in conventional slickwater,making it difficult to form fiber-proppant agglomerate with proppant and exhibit limited effectiveness.To solve these problems,a novel structure stabilizer(SS)is developed.Through microscopic structural observations and performance evaluations in indoor experiments,the mechanism of proppant placement under the action of the SS and the effects of the SS on proppant placement dimensions and fracture conductivity were elucidated.The SS facilitates the formation of robust fiber-proppant agglomerates by polymer,fiber,and quartz sand.Compared to bare proppants,these agglomerates exhibit reduced density,increased volume,and enlarged contact area with the fluid during settlement,leading to heightened buoyancy and drag forces,ultimately resulting in slower settling velocities and enhanced transportability into deeper regions of the fracture.Co-injecting the fiber and the SS alongside the proppant into the reservoir effectively reduces the fiber escape rate,increases the proppant volume in the slickwater,and boosts the proppant placement height,conveyance distance and fracture conductivity,while also decreasing the proppant backflow.Experimental results indicate an optimal SS mass fraction of 0.3%.The application of this SS in over 80 wells targeting tight gas,shale oil,and shale gas reservoirs has substantiated its strong adaptability and general suitability for meeting the production enhancement,cost reduction,and sand control requirements of such wells. 展开更多
关键词 hydraulic fracturing PROPPANT structure stabilizer placement mechanism CONDUCTIVITY proppant backflow rate
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Characteristics of proppant transport and placement within rough hydraulic fractures
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作者 HUANG Hai ZHENG Yong +5 位作者 WANG Yi WANG Haizhu NI Jun WANG Bin YANG Bing ZHANG Wentong 《Petroleum Exploration and Development》 SCIE 2024年第2期453-463,共11页
A three-dimensional reconstruction of rough fracture surfaces of hydraulically fractured rock outcrops is carried out by casting process,a large-scale experimental setup for visualizing rough fractures is built to per... A three-dimensional reconstruction of rough fracture surfaces of hydraulically fractured rock outcrops is carried out by casting process,a large-scale experimental setup for visualizing rough fractures is built to perform proppant transport experiments.The typical characteristics of proppant transport and placement in rough fractures and its intrinsic mechanisms are investigated,and the influences of fracture inclination,fracture width and fracturing fluid viscosity on proppant transport and placement in rough fractures are analyzed.The results show that the rough fractures cause variations in the shape of the flow channel and the fluid flow pattern,resulting in the bridging buildup during proppant transport to form unfilled zone,the emergence of multiple complex flow patterns such as channeling,reverse flow and bypassing of sand-carrying fluid,and the influence on the stability of the sand dune.The proppant has a higher placement rate in inclined rough fractures,with a maximum increase of 22.16 percentage points in the experiments compared to vertical fractures,but exhibits poor stability of the sand dune.Reduced fracture width aggravates the bridging of proppant and induces higher pumping pressure.Increasing the viscosity of the fracturing fluid can weaken the proppant bridging phenomenon caused by the rough fractures. 展开更多
关键词 reservoir fracturing rough fracture PROPPANT transport and placement characteristics bridging buildup
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Efficient Digital Twin Placement for Blockchain-Empowered Wireless Computing Power Network
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作者 Wei Wu Liang Yu +2 位作者 Liping Yang Yadong Zhang Peng Wang 《Computers, Materials & Continua》 SCIE EI 2024年第7期587-603,共17页
As an open network architecture,Wireless Computing PowerNetworks(WCPN)pose newchallenges for achieving efficient and secure resource management in networks,because of issues such as insecure communication channels and... As an open network architecture,Wireless Computing PowerNetworks(WCPN)pose newchallenges for achieving efficient and secure resource management in networks,because of issues such as insecure communication channels and untrusted device terminals.Blockchain,as a shared,immutable distributed ledger,provides a secure resource management solution for WCPN.However,integrating blockchain into WCPN faces challenges like device heterogeneity,monitoring communication states,and dynamic network nature.Whereas Digital Twins(DT)can accurately maintain digital models of physical entities through real-time data updates and self-learning,enabling continuous optimization of WCPN,improving synchronization performance,ensuring real-time accuracy,and supporting smooth operation of WCPN services.In this paper,we propose a DT for blockchain-empowered WCPN architecture that guarantees real-time data transmission between physical entities and digital models.We adopt an enumeration-based optimal placement algorithm(EOPA)and an improved simulated annealing-based near-optimal placement algorithm(ISAPA)to achieve minimum average DT synchronization latency under the constraint of DT error.Numerical results show that the proposed solution in this paper outperforms benchmarks in terms of average synchronization latency. 展开更多
关键词 Wireless computing power network blockchain digital twin placement minimum synchronization latency
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Analysis of the Application Effect of Tracheal Stent Placement in the Nutritional Support Treatment of Tracheoesophageal Fistula
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作者 Xiaoqing An Xiaoting An Yiqing Qu 《Proceedings of Anticancer Research》 2024年第3期104-108,共5页
Objective:To evaluate and analyze the application effect of tracheal stent placement in nutritional support therapy for tracheoesophageal fistula.Methods:Clinical data of 32 patients who underwent nutritional support ... Objective:To evaluate and analyze the application effect of tracheal stent placement in nutritional support therapy for tracheoesophageal fistula.Methods:Clinical data of 32 patients who underwent nutritional support therapy for tracheoesophageal fistula in our hospital from September 2021 to September 2022 were collected,and all patients underwent tracheal silicone stenting,comparing dyspnea classification and Karnofsky score before and after stenting,and conducting post-treatment follow-up.Results:In 32 patients with tracheoesophageal fistula,dyspnea grading improved from grades III and IV to grades 0 to II.Before treatment,10 patients(31.06%)were in grade IV,17 patients(53.12%)were in grade III,and five patients(15.62)were in grade II;after treatment,13 patients(40.63%)were in grade I,12 patients(37.50%)were in grade I,and seven patients(21.87%)were in grade 0(P<0.05);Karnofsky score(37.52±4.86 before treatment)improved significantly to 71.39±8.24 one week after treatment(P<0.05).Nine patients with tracheoesophageal fistula were placed with silicone Y14-10-10 stent,11 with silicone 18-14-14 stent,three with silicone Y15-12-12,and seven with silicone stent 16-13-13.Conclusion:Silicone tracheobronchial stent placement for the treatment of tracheoesophageal fistula is technically feasible,simple,and safe,with reliable near-term efficacy,and is worthy of popularization and application. 展开更多
关键词 Tracheal stent placement Tracheoesophageal fistula Nutritional support
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Clinical Study on Improving Articulation Clarity in Spastic Cerebral Palsy with 120 Cases of Oral-Facial Acupressure Combined with Oral Placement Therapy
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作者 Yongjie Gong Kai Wu +4 位作者 Shan Yang Yalan Yu Xiaobo Zhang Fei Rong Yuan He 《Journal of Clinical and Nursing Research》 2024年第5期30-38,共9页
Objective:To observe the efficacy of oral-facial acupressure combined with oral placement therapy(OPT)in improving articulation clarity in 120 children with spastic cerebral palsy,and to explore effective therapeutic ... Objective:To observe the efficacy of oral-facial acupressure combined with oral placement therapy(OPT)in improving articulation clarity in 120 children with spastic cerebral palsy,and to explore effective therapeutic solutions for speech disorders associated with spastic cerebral palsy.Methods:A total of 120 children with spastic cerebral palsy and speech disorders,meeting the inclusion criteria,were randomly assigned into two groups:60 cases in the treatment group and 60 cases in the control group.The treatment group received orofacial acupressure combined with OPT,while the control group received only OPT.The Oral Motor Function Assessment Scale(OMFAS),developed by the China Rehabilitation Research Centre(CRRC),was used to evaluate the treatment outcomes before and after the intervention.Results:After the treatment,both the treatment and control groups showed improved mobility of the mandible,lips,and tongue.However,the treatment group exhibited significantly better improvement than the control group,with the difference between the two groups being statistically significant(P<0.05).Conclusion:Oral-facial acupressure combined with OPT can effectively improve articulation clarity in children with spastic cerebral palsy.This combined therapy is recommended for clinical promotion and application. 展开更多
关键词 Oral-facial acupressure Oral placement therapy(OPT) Speech disorders in children with spastic cerebral palsy Speech intelligibility
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Better Initial Placement Algorithm for Large-Scale Mixed-Mode Detailed Placement
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作者 周强 罗丽娟 +1 位作者 洪先龙 周汉斌 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2004年第7期784-789,共6页
An algorithm is presented for better legal solution in detailed placement of large scale mixed macros and standard cells IC design.Due to the limitation of computing complexity,an effective and efficient initial place... An algorithm is presented for better legal solution in detailed placement of large scale mixed macros and standard cells IC design.Due to the limitation of computing complexity,an effective and efficient initial placement is very important for detailed placement.Novelty of this algorithm lies in a better solution at initial stage by using network flow method to satisfy row capacity constraint and the thought of linear placement problem(LPP) to resolve overlaps.Moreover,divide and conquer strategy and other simplified methods are adopted to minimize complexity.Experimental results show that the algorithm can get an average of 16% wire length improvement on PAFLO in reasonable CPU time. 展开更多
关键词 placement detailed placement mixed mode placement ALGORITHM
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Multi-Layer Fog-Cloud Architecture for Optimizing the Placement of IoT Applications in Smart Cities
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作者 Mohammad Aldossary 《Computers, Materials & Continua》 SCIE EI 2023年第4期633-649,共17页
In the smart city paradigm, the deployment of Internet of Things(IoT) services and solutions requires extensive communication and computingresources to place and process IoT applications in real time, which consumesa ... In the smart city paradigm, the deployment of Internet of Things(IoT) services and solutions requires extensive communication and computingresources to place and process IoT applications in real time, which consumesa lot of energy and increases operational costs. Usually, IoT applications areplaced in the cloud to provide high-quality services and scalable resources.However, the existing cloud-based approach should consider the above constraintsto efficiently place and process IoT applications. In this paper, anefficient optimization approach for placing IoT applications in a multi-layerfog-cloud environment is proposed using a mathematical model (Mixed-Integer Linear Programming (MILP)). This approach takes into accountIoT application requirements, available resource capacities, and geographicallocations of servers, which would help optimize IoT application placementdecisions, considering multiple objectives such as data transmission, powerconsumption, and cost. Simulation experiments were conducted with variousIoT applications (e.g., augmented reality, infotainment, healthcare, andcompute-intensive) to simulate realistic scenarios. The results showed thatthe proposed approach outperformed the existing cloud-based approach interms of reducing data transmission by 64% and the associated processingand networking power consumption costs by up to 78%. Finally, a heuristicapproach was developed to validate and imitate the presented approach. Itshowed comparable outcomes to the proposed model, with the gap betweenthem reach to a maximum of 5.4% of the total power consumption. 展开更多
关键词 IoT application placement fog-cloud computing power consumption data transmission optimization smart cities
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Sea Turtle Foraging Optimization-Based Controller Placement with Blockchain-Assisted Intrusion Detection in Software-Defined Networks
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作者 Sultan Alkhliwi 《Computers, Materials & Continua》 SCIE EI 2023年第6期4735-4752,共18页
Software-defined networking(SDN)algorithms are gaining increas-ing interest and are making networks flexible and agile.The basic idea of SDN is to move the control planes to more than one server’s named controllers a... Software-defined networking(SDN)algorithms are gaining increas-ing interest and are making networks flexible and agile.The basic idea of SDN is to move the control planes to more than one server’s named controllers and limit the data planes to numerous sending network components,enabling flexible and dynamic network management.A distinctive characteristic of SDN is that it can logically centralize the control plane by utilizing many physical controllers.The deployment of the controller—that is,the controller placement problem(CPP)—becomes a vital model challenge.Through the advancements of blockchain technology,data integrity between nodes can be enhanced with no requirement for a trusted third party.Using the lat-est developments in blockchain technology,this article designs a novel sea turtle foraging optimization algorithm for the controller placement problem(STFOA-CPP)with blockchain-based intrusion detection in an SDN environ-ment.The major intention of the STFOA-CPP technique is the maximization of lifetime,network connectivity,and load balancing with the minimization of latency.In addition,the STFOA-CPP technique is based on the sea turtles’food-searching characteristics of tracking the odour path of dimethyl sulphide(DMS)released from food sources.Moreover,the presented STFOA-CPP technique can adapt with the controller’s count mandated and the shift to controller mapping to variable network traffic.Finally,the blockchain can inspect the data integrity,determine significantly malicious input,and improve the robust nature of developing a trust relationship between sev-eral nodes in the SDN.To demonstrate the improved performance of the STFOA-CPP algorithm,a wide-ranging experimental analysis was carried out.The extensive comparison study highlighted the improved outcomes of the STFOA-CPP technique over other recent approaches. 展开更多
关键词 Software-defined networking NP hard problem metaheuristics controller placement problem objective function
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Improved Harris Hawks Optimization Algorithm Based Data Placement Strategy for Integrated Cloud and Edge Computing
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作者 V.Nivethitha G.Aghila 《Intelligent Automation & Soft Computing》 SCIE 2023年第7期887-904,共18页
Cloud computing is considered to facilitate a more cost-effective way to deploy scientific workflows.The individual tasks of a scientific work-flow necessitate a diversified number of large states that are spatially l... Cloud computing is considered to facilitate a more cost-effective way to deploy scientific workflows.The individual tasks of a scientific work-flow necessitate a diversified number of large states that are spatially located in different datacenters,thereby resulting in huge delays during data transmis-sion.Edge computing minimizes the delays in data transmission and supports the fixed storage strategy for scientific workflow private datasets.Therefore,this fixed storage strategy creates huge amount of bottleneck in its storage capacity.At this juncture,integrating the merits of cloud computing and edge computing during the process of rationalizing the data placement of scientific workflows and optimizing the energy and time incurred in data transmission across different datacentres remains a challenge.In this paper,Adaptive Cooperative Foraging and Dispersed Foraging Strategies-Improved Harris Hawks Optimization Algorithm(ACF-DFS-HHOA)is proposed for optimizing the energy and data transmission time in the event of placing data for a specific scientific workflow.This ACF-DFS-HHOA considered the factors influencing transmission delay and energy consumption of data centers into account during the process of rationalizing the data placement of scientific workflows.The adaptive cooperative and dispersed foraging strategy is included in HHOA to guide the position updates that improve population diversity and effectively prevent the algorithm from being trapped into local optimality points.The experimental results of ACF-DFS-HHOA confirmed its predominance in minimizing energy and data transmission time incurred during workflow execution. 展开更多
关键词 Edge computing cloud computing scientific workflow data placement energy of datacenters data transmission time
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Ruppert's Delaunay Triangulation Refinement Scheme for Optimal RSUs Placement in Vehicle to Infrastructure Communication Network
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作者 Selvakumari P Chinnasamy A +1 位作者 Sree Rathna Lakshmi NVS Sheela D 《China Communications》 SCIE CSCD 2023年第7期303-320,共18页
Road Side Units(RSUs)are the essential component of vehicular communication for the objective of improving safety and mobility in the road transportation.RSUs are generally deployed at the roadside and more specifical... Road Side Units(RSUs)are the essential component of vehicular communication for the objective of improving safety and mobility in the road transportation.RSUs are generally deployed at the roadside and more specifically at the intersections in order to collect traffic information from the vehicles and disseminate alarms and messages in emergency situations to the neighborhood vehicles cooperating with the network.However,the development of a predominant RSUs placement algorithm for ensuring competent communication in VANETs is a challenging issue due to the hindrance of obstacles like water bodies,trees and buildings.In this paper,Ruppert’s Delaunay Triangulation Refinement Scheme(RDTRS)for optimal RSUs placement is proposed for accurately estimating the optimal number of RSUs that has the possibility of enhancing the area of coverage during data communication.This RDTRS is proposed by considering the maximum number of factors such as global coverage,intersection popularity,vehicle density and obstacles present in the map for optimal RSUs placement,which is considered as the core improvement over the existing RSUs optimal placement strategies.It is contributed for deploying requisite RSUs with essential transmission range for maximal coverage in the convex map such that each position of the map could be effectively covered by at least one RSU in the presence of obstacles.The simulation experiments of the proposed RDTRS are conducted with complex road traffic environments.The results of this proposed RDTRS confirmed its predominance in reducing the end-to-end delay by 21.32%,packet loss by 9.38%with improved packet delivery rate of 10.68%,compared to the benchmarked schemes. 展开更多
关键词 road side units(RSUs) ruppert’s delau-nay triangulation refinement area of global coverage optimal RSUs placement
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Different percutaneous transhepatic biliary stent placements and catheter drainage in the treatment of middle and low malignant biliary obstruction
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作者 Yao-Bo Yang Zhao-Yong Yan +3 位作者 Yang Jiao Wei-Hao Yang Qi Cui Si-Pan Chen 《World Journal of Gastrointestinal Surgery》 SCIE 2023年第7期1397-1404,共8页
BACKGROUND For cases of middle and low biliary obstruction with left and right hepatic duct dilatation,the type of approach and whether different approaches affect the difficulty of puncture operation and intraoperati... BACKGROUND For cases of middle and low biliary obstruction with left and right hepatic duct dilatation,the type of approach and whether different approaches affect the difficulty of puncture operation and intraoperative and postoperative complications have not been discussed in detail.AIM To compare the efficacy of different percutaneous transhepatic biliary stent placements and catheter drainage in treating middle and low biliary obstruction.METHODS A retrospective analysis was performed on the medical records of 424 patients with middle and low biliary obstruction who underwent percutaneous liver puncture biliary stent placement and catheter drainage at the Department of Interventional Radiology,Shaanxi Provincial People’s Hospital between March 2016 and March 2022.Based on the puncture path,patients were categorized into two groups:Subxiphoid left hepatic lobe approach group(Group A,224 cases)and right intercostal,right hepatic lobe approach group(Group B,200 cases).Liver function improvement,postoperative biliary bleeding incidence,postoperative pain duration,and abdominal effusion leakage around the drainage tube were compared between the two groups at 3 d and 1 wk after the surgery.Patient survival time was recorded during follow-up.RESULTS All 424 surgeries were successful without adverse events.Group A comprised 224 cases,and Group B had 200 cases.There was no statistically significant difference in basic data between Group A and Group B(P>0.05).No significant difference in postoperative biliary bleeding incidence was observed between the groups(P>0.05).The decreased rates for total bilirubin(Group A:69.23±4.50,Group B:63.79±5.65),direct bilirubin(Group A:79.30±11.19,Group B:63.62±5.64),and alkaline phosphatase(Group A:60.51±12.23,Group B:42.68±23.56)in the 1st wk after surgery were significantly faster in Group A than in Group B.The decreased rate of gamma-glutamyl transpeptidase was also significantly faster in Group A at both 3 d(Group A:40.56±10.32,Group B:32.22±5.12)and 1 wk(Group A:73.19±7.05,Group B:58.81±18.98)after surgery(P<0.05).Group A experienced significantly less peritoneal effusion leakage around the drainage tube than Group B(P<0.05).The patient survival rate was higher in Group A compared to Group B(P<0.05).CONCLUSION In treating jaundice patients with middle and low biliary obstruction,a percutaneous left liver puncture demonstrated better clinical efficacy than a percutaneous right liver puncture. 展开更多
关键词 Biliary obstruction Puncture route Stent placement Survival rate Malignant tumor Digestive tract
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Optimal Placement and Sizing of Distributed Generations for Power Losses Minimization Using PSO-Based Deep Learning Techniques
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作者 Bello-Pierre Ngoussandou Nicodem Nisso +1 位作者 Dieudonné Kaoga Kidmo   Kitmo 《Smart Grid and Renewable Energy》 2023年第9期169-181,共13页
The integration of distributed generations (DGs) into distribution systems (DSs) is increasingly becoming a solution for compensating for isolated local energy systems (ILESs). Additionally, distributed generations ar... The integration of distributed generations (DGs) into distribution systems (DSs) is increasingly becoming a solution for compensating for isolated local energy systems (ILESs). Additionally, distributed generations are used for self-consumption with excess energy injected into centralized grids (CGs). However, the improper sizing of renewable energy systems (RESs) exposes the entire system to power losses. This work presents an optimization of a system consisting of distributed generations. Firstly, PSO algorithms evaluate the size of the entire system on the IEEE bus 14 test standard. Secondly, the size of the system is allocated using improved Particles Swarm Optimization (IPSO). The convergence speed of the objective function enables a conjecture to be made about the robustness of the proposed system. The power and voltage profile on the IEEE 14-bus standard displays a decrease in power losses and an appropriate response to energy demands (EDs), validating the proposed method. 展开更多
关键词 Distributed Generations Deep Learning Techniques Improved Particle Swarm Optimization Power Losses Power Losses Minimization Optimal placement
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Placement distance of freeway exit advance guide sign and its safety impacts 被引量:3
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作者 郭唐仪 邓卫 +1 位作者 侯建生 Lu John 《Journal of Southeast University(English Edition)》 EI CAS 2010年第4期622-627,共6页
To remedy the empirical pitfalls of current chinese specifications and MUTCD 2009 guidelines in determining the placement distance of freeway exit advance guide signs,the driving maneuver of exiting traffic is analyze... To remedy the empirical pitfalls of current chinese specifications and MUTCD 2009 guidelines in determining the placement distance of freeway exit advance guide signs,the driving maneuver of exiting traffic is analyzed and the factors influencing placement distance are explored.Variables including the number of lanes,lane width,lane-changing time,driver's visual characteristics,sign installation methods and operating speeds on both freeway mainlines and exit ramps are found significant in explaining exit safety.Three different installation methods,namely ground installation,overhead installation and median installation,are introduced and their applicable conditions are given.Models,with the same structure among the three installation methods,are developed to compute the placement distance under different roadway geometric and traffic conditions.Taking overhead installation as an example,simulation results in TSIS-CORSIM show that the proposed distance reduces the number of lane changes in the area from the ramp nose to 500 m upstream by 58.93% compared with current Chinese specifications and 27.35% compared with MUTCD 2009 guidelines.Thus,the distances recommended in this paper have a better safety performance. 展开更多
关键词 FREEWAY advance guide sign placement distance safety impact lane change
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Fame:A Fast Detailed Placement Algorithm for Standard\| Cell Layout Based on Mixed Mincut and Enumeration 被引量:1
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作者 姚波 侯文婷 +1 位作者 洪先龙 蔡懿慈 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2000年第8期744-753,共10页
Rapid progress in manufacturing greatly challenges to the VLSI physical design in both speed and performance. A fast detailed placement algorithm, FAME is presented in this paper, according to these demands. It inhe... Rapid progress in manufacturing greatly challenges to the VLSI physical design in both speed and performance. A fast detailed placement algorithm, FAME is presented in this paper, according to these demands. It inherits the optimal positions of cells given by a global placer and exact position to each cell by local optimization. FM Mincut heuristic and local enumeration are used to optimize the total wirelength in y and x directions respectively, and a two way mixed optimizing flow is adopted to combine the two methods for a better performance. Furthermore, a better enumeration strategy is introduced to speed up the algorithm. An extension dealing with blockages in placement has also been discussed. Experimental results show that FAME runs 4 times faster than RITUAL and achieves a 5% short in total wirelength on average. 展开更多
关键词 detailed placement layout VLSI mincut optimization
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Large Scale VLSI Module Placement Using LFF Heuristics by Stages
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作者 魏少俊 董社勤 +1 位作者 洪先龙 吴有亮 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2006年第5期812-818,共7页
We present a deterministic algorithm for large-scale VLSI module placement. Following the less flexibility first (LFF) principle,we simulate a manual packing process in which the concept of placement by stages is in... We present a deterministic algorithm for large-scale VLSI module placement. Following the less flexibility first (LFF) principle,we simulate a manual packing process in which the concept of placement by stages is introduced to reduce the overall evaluation complexity. The complexity of the proposed algorithm is (N1 + N2 ) × O( n^2 ) + N3× O(n^4lgn) ,where N1, N2 ,and N3 denote the number of modules in each stage, N1 + N2 + N3 = n, and N3〈〈 n. This complexity is much less than the original time complexity of O(n^5lgn). Experimental results indicate that this approach is quite promising. 展开更多
关键词 FLOORPLANNING placements large scale LFF principle deterministic placement algorithm
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Study on Component Synthesis Active Vibration Suppression Method Using Zero-placement Technique 被引量:4
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作者 张建英 刘暾 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2008年第4期304-312,共9页
The component synthesis active vibration suppression method (CSVS) can be applied to suppress the vibration of flexible systems. By this method, several same or similar time-varying components are arranged according... The component synthesis active vibration suppression method (CSVS) can be applied to suppress the vibration of flexible systems. By this method, several same or similar time-varying components are arranged according to certain rules along the time axis. The synthesized command can suppress the arbitrary unwanted vibration harmonic while achieving the desired rigid body motion. The number of the components increases rapidly when the number of harmonic vibration is growing. In this article, the CSVS based on zero-placement technique is used to construct the synthesized command to suppress the multi-harmonics simultaneously in the discrete domain. The nature of zero-placement method is to put enough zeros to cancel system poles at necessary points. The designed synthesized command has equal time intervals between each component and which is much easier to be implemented. Using this method, the number of components increases linearly with the increasing of the number of being suppressed harmonics. For the spacecraft with flexible appendages, CSVS based on zero-placement is used to design the time optimal large angle maneuver control strategy. Simulations have verified the validity and superiority of the proposed approach. 展开更多
关键词 flexible structure vibration suppression component synthesis active vibration suppression method zero-placement technique
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A New Clustering-Based Partitioning Method for VLSI Mixed-Mode Placement
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作者 吕勇强 洪先龙 +2 位作者 杨长旗 周强 蔡懿慈 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2005年第1期22-28,共7页
An efficient partitioning algorithm for mixed-mode placement,extended-MFFC-based partitioning,is presented.It combines the bottom-up clustering and the top-down partitioning together.To do this,designers can not only ... An efficient partitioning algorithm for mixed-mode placement,extended-MFFC-based partitioning,is presented.It combines the bottom-up clustering and the top-down partitioning together.To do this,designers can not only cluster cells considering logic dependency but also partition them aiming at min-cut.Experimental results show that extended-MFFC-based partitioning performs well in mixed-mode placement with big pre-designed blocks.By comparison with the famous partitioning package HMETIS,this partitioning proves its remarkable function in mixed-mode placement. 展开更多
关键词 mixed-mode placement extended MFFC HMETIS CLUSTERING partitioning
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A New Clock-Driven ECO Placement Algorithm Based on Table-Lookup Delay Model
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作者 刘毅 洪先龙 +2 位作者 蔡懿慈 吴为民 Chung-Wen Albert Tsao 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2002年第5期473-478,共6页
A new clock-driven ECO placement algorithm is pr es ented for standard-cell layout design based on the table-lookup delay model.It considers useful clock skew information in the placement stage.It also modifies the ... A new clock-driven ECO placement algorithm is pr es ented for standard-cell layout design based on the table-lookup delay model.It considers useful clock skew information in the placement stage.It also modifies the positions of cells locally to make better preparation for the clock routing . Experimental results show that with little influence to other circuit performa nce,the algorithm can improve permissible skew range distribution evidently. 展开更多
关键词 CLOCK-DRIVEN incremental placement useful skew permissibl e skew range
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