检索结果-南通市图书馆

Analytical modeling of cache-enabled heterogeneous networks using Poisson cluster processes

在线全文

学校读者我要写书评

暂无评论

Digital Communications and Networks 2024年第5期10卷 1439-1447页

作者： Junhui Zhao Lihua Yang Xiaoting Ma Ziyang Zhang School of Electronic and Information Engineering Beijing Jiaotong University School of Information Engineering East China Jiaotong University Lenovo Research Lenovo Group Limited

The dual frequency Heterogeneous Network(HetNet),including sub-6 GHz networks together with Millimeter Wave(mmWave),achieves the high data rates of user in the networks with *** cache-enabled HetNets with hotspots are investigated using an analytical framework in which Macro Base Stations(MBSs) and hotspot centers are treated as two independent homogeneous Poisson Point Processes(PPPs),and locations of Small Base Stations(SBSs) and users are modeled as two Poisson Cluster Processes(PCPs).Under the PCP-based modeling method and the Most Popular Caching(MPC) scheme,we propose a cache-enabled association strategy for HetNets with limited storage *** performance of association probability and coverage probability is explicitly derived,and Monte Carlo simulation is utilized to verify that the results are *** outcomes of the simulation present the influence of antenna configuration and cache capacities of MBSs and SBSs on network *** optimization of the standard deviation ratio of SBSs and users of association probability is enabled by our analysis.

关键词： Heterogeneous networks Millimeter wave Poisson cluster processes Caching Stochastic geometry

Inclusive Multiple Models(IMM)for predicting groundwater levels and treating heterogeneity

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2021年第2期12卷 713-724页

作者： Rahman Khatibi Ata Allah Nadiri GTEV-ReX limited SwindonUK Department of Earth Sciences Faculty of Natural ScienceUniversity of Tabriz29 Bahman BoulevardTabrizEast AzerbaijanIran Institute of Environment University of TabrizEast AzerbaijanIran

An explicit model management framework is introduced for predictive Groundwater Levels(GWL),particularly suitable to Observation Wells(OWs)with sparse and possibly heterogeneous *** framework implements Multiple Models(MM)under the architecture of organising them at levels,as follows:(i)Level 0:treat heterogeneity in the data,***-Organised Mapping(SOM)to classify the OWs;and decide on model structure,*** a grey box model to predict GWLs.(ii)Level 1:construct MMs,*** Fuzzy Logic(FL)and one Neurofuzzy(NF)models.(iii)Level 2:formulate strategies to combine the MM at Level 1,for which the paper uses Artificial Neural Networks(Strategy 1)and simple averaging(Strategy 2).Whilst the above model management strategy is novel,a critical view is presented,according to which modelling practices are:Inclusive Multiple Modelling(IMM)practices contrasted with existing practices,branded by the paper as Exclusionary Multiple Modelling(EMM).Scientific thinking over IMMs is captured as a framework with four dimensions:Model Reuse(MR),Hierarchical Recursion(HR),Elastic Learning Environment(ELE)and Goal Orientation(GO)and these together make the acronym of ***,IMM-RHEO is piloted in the aquifer of Tabriz Plain with sparse and possibly heterogeneous *** results provide some evidence that(i)IMM at two levels improves on the accuracy of individual models;and(ii)model combinations in IMM practices bring‘model-learning’into fashion for learning with the goal to explain baseline conditions and impacts of subsequent management changes.

关键词： Artificial intelligence Exclusionary multiple modelling(EMM) Groundwater level prediction Inclusive multiple modelling(IMM) Model management practices

Effect of copper loading on texture,structure and catalytic performance of Cu/SiO_2 catalyst for hydrogenation of dimethyl oxalate to ethylene glycol

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2012年第5期21卷 563-570页

作者： Bo Zhang Shengguo Hui Suhua Zhang Yang Ji Wei Li Dingye Fang State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai 200237China Pujing Chemical Industry(Sha)limited Shanghai 200231China

Cu/SiO2 catalysts prepared by a convenient and efficient method using the urea hydrolysis deposition-precipitation （UHDP） technique have been proposed focusing on the effect of copper *** texture,structure and composition are systematically characterized by ICP,FTIR,N 2-physisorption,N2O chemisorption,TPR,XRD and *** formation of copper phyllosilicate is observed in Cu/SiO2 catalyst by adopting UHDP method,and the amount of copper phyllosilicate is related to copper *** is found the structure properties and catalytic performance is profoundly affected by the amount of copper *** excellent catalytic activity is attributed to the synergetic effect between Cu0 and Cu ＋.DMO conversion and EG selectivity are determined by the amount of Cu0 and Cu＋,*** proper copper loading （30 wt%） provides with the highest ratio of Cu ＋ /Cu0,giving rise to the highest EG yield of 95% under the reaction conditions of p=2.0 MPa,T=473 K,H2/DMO=80 and LHSV=1.0h-1.

关键词： Cu/SiO2 copper loading dimethyl oxalate ethylene glycol copper phyllosilicate

Carbon nanotube enhanced water-based drilling fluid for high temperature and high salinity deep resource development

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2022年第2期19卷 916-926页

作者： Jing-Ping Liu Xian-Fa Zhang Wen-Chao Zhang Kai-He Lv Yin-Rui Bai Jin-Tang Wang Xian-Bin Huang Jia-Feng Jin Jin-Sheng Sun College of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580China CNPC Engineering Technology R&D Company limited Beijing 102206China

Drilling fluids face failure during drilling deep reservoir with high temperature and high *** experimental results show that high temperature and salinity reduce the negative charge on the surface of bentonite in the drilling fluid and cause the coalescence of bentonite *** a result,the particles coalesce,the grid structure is destroyed,and the rheological properties,rock-carrying capacity and filtration properties are *** resolve the foregoing,in this study,0.05-wt%carbon nanotubes are introduced into a 4%bentonite drilling fluid under conditions where the temperature and concentration of added Na Cl reach 180°C and 10 wt%,*** carbon nanotubes adsorb on the bentonite surface and increase the space among bentonite *** steric hindrance prevents the coalescence of bentonite in high temperature and high salt *** bentonite maintains the small size distribution of bentonite and supports the bentonite grid structure in the drilling *** a result,the rock-carrying capacity of the drilling fluid increases by 85.1%.Moreover,the mud cake formed by the accumulation of small-sized bentonite particles is dense;consequently,the filtration of bentonite drilling fluid reduced by 30.2%.

关键词： High temperature Water-based drilling fluid High salinity Carbon nanotube Deep resources

Curing kinetics and plugging mechanism of high strength curable resin plugging material

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第5期21卷 3446-3463页

作者： Jing-Bin Yang Ying-Rui Bai Jin-Sheng Sun Kai-He Lv School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina CNPC Engineering Technology R&D Company limited Beijing102206China

Lost circulation, a recurring peril during drilling operations, entails substantial loss of drilling fluid and dire consequences upon its infiltration into the formation. As drilling depth escalates, the formation temperature and pressure intensify, imposing exacting demands on plug materials. In this study, a kind of controllable curing resin with dense cross-network structure was prepared by the method of solution stepwise ring-opening polymerization. The resin plugging material investigated in this study is a continuous phase material that offers effortless injection, robust filling capabilities, exceptional retention, and underground curing or crosslinking with high strength. Its versatility is not constrained by fracture-cavity lose channels, making it suitable for fulfilling the essential needs of various fracture-cavity combinations when plugging fracture-cavity carbonate rocks. Notably, the curing duration can be fine-tuned within the span of 3-7 h, catering to the plugging of drilling fluid losing of diverse fracture dimensions. Experimental scrutiny encompassed the rheological properties and curing behavior of the resin plugging system, unraveling the intricacies of the curing process and establishing a cogent kinetic model. The experimental results show that the urea-formaldehyde resin plugging material has a tight chain or network structure. When the concentration of the urea-formaldehyde resin plugging system solution remains below 30%, the viscosity clocks in at a meager 10 mPa·s. Optimum curing transpires at 60℃, showcasing impressive resilience to saline conditions. Remarkably, when immersed in a composite saltwater environment containing 50000 mg/L NaCl and 100000 mg/L CaCl_(2), the urea-formaldehyde resin consolidates into an even more compact network structure, culminating in an outstanding compressive strength of 41.5 MPa. Through resolving the correlation between conversion and the apparent activation energy of the non-isothermal DSC curing reac

关键词： Urea-formaldehyde resin Rheological property Curing property Curing kinetics Plugging mechanism

Synthesis and mechanism of environmentally friendly high temperature and high salt resistant lubricants

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2023年第5期20卷 3110-3118页

作者： Zong-Lun Wang Jin-Sheng Sun Jing-Ping Liu Kai-He Lv Zi-Hua Shao Xian-Fa Zhang Zhe Xu Zhi-Wen Dai Ning Huang School of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580ShandongChina CNPC Engineering Technology R&D Company limited Beijing 102206China

With the exploration and development of deep and ultra-deep oil and gas,high torque and high friction during the drilling of deep and ultra-deep wells become one of the key issues affecting drilling safety and drilling ***,the high temperature and high salt problem in deep formations is prominent,which poses a major challenge to the lubricity of drilling fluids under high temperature and high *** paper reports an organic borate ester SOP as an environmentally friendly drilling fluid *** performance evaluation results show that when 1%lubricant SOP is added to the fresh water-based mud,the lubrication coefficient decreases from 0.631 to 0.046,and the reduction rate of lubrication coefficient is 92.7%.Under the conditions of 210℃ and 30%NaCl,the reduction rate of lubricating coefficient of the base slurry with 1%SOP was still remain 81.5%.After adding 1%SOP,the wear volume decreased by 94.11%compared with the base *** contact resistance experiment during the friction process shows that SOP can form a thick adsorption film on the friction surface under high temperature and high salt conditions,thus effectively reducing the friction *** dynamics simulation shows that lubricant SOP can be physically adsorbed on the surface of drilling tool and borehole wall through hydrogen bond and van der Waals *** analysis further shows that SOP adsorbs on the friction surface and reacts with metal atoms on the friction surface to form a chemically reactive ***,under high temperature and high salt conditions,the synergistic effect of physical adsorption film and chemical reaction film effectively reduces the frictional resistance and wear of the friction *** addition,SOP is non-toxic and easy to ***,SOP is a highly effective and environmentally friendly lubricant in high temperature and high salt drilling fluid.

关键词： Deep oil and gas Lubricant Environmentally friendly Water-based drilling fluid Molecular dynamics simulations

Development and performance evaluation of high temperature resistant strong adsorption rigid blocking agent

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第4期21卷 2650-2662页

作者： Zhe Xu Jin-Sheng Sun Jing-Ping Liu Kai-He Lv Xiao-Dong Dong Zong-Lun Wang Tai-Feng Zhang Yuan-Wei Sun Zhi-Wen Dai School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina CNPC Engineering Technology R&D Company limited Beijing102206China

As drilling wells continue to move into deep ultra-deep layers,the requirements for temperature resistance of drilling fluid treatments are getting higher and *** them,blocking agent,as one of the key treatment agents,has also become a hot spot of *** this study,a high temperature resistant strong adsorption rigid blocking agent(QW-1)was prepared using KH570 modified silica,acrylamide(AM)and allyltrimethylammonium chloride(TMAAC).QW-1 has good thermal stability,average particle size of 1.46μm,water contact angle of 10.5.,has a strong hydrophilicity,can be well dispersed in *** experimental results showed that when 2 wt%QW-1 was added to recipe A(4 wt%bentonite slurry+0.5 wt%DSP-1(filtration loss depressant)),the API filtration loss decreased from 7.8to 6.4 m *** aging at 240.C,the API loss of filtration was reduced from 21 to 14 m L,which has certain performance of high temperature loss of *** the same time,it is effective in sealing 80-100mesh and 100-120 mesh sand beds as well as 3 and 5μm ceramic sand *** the same conditions,the blocking performance was superior to silica(5μm)and calcium carbonate(2.6μm).In addition,the mechanism of action of QW-1 was further *** results show that QW-1 with amide and quaternary ammonium groups on the molecular chain can be adsorbed onto the surface of clay particles through hydrogen bonding and electrostatic interaction to form a dense blocking layer,thus preventing further intrusion of drilling fluid into the formation.

关键词： High adsorption Rigid microsphere High temperature resistance Blocking performance

Elevational diversity gradients across seed plant taxonomic levels in the Lancang River Nature Reserve： role of temperature, water and the mid-domain effect

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 2018年第4期29卷 1110-1116页

作者： Jie Gao Xing Zhang Zhifeng Luo Junjie Lan Yanhong Liu Forestry College of Beijing Forestry University No. 35 Qinghua East Road Beijing 100083 People's Republic of China Powerchina Kunming Engineering Corporation limited No 115 Renmin East Road Kunming 650051 People's Republic of China

It remains unclear whether the elevational diversity gradients observed in seed plants across different taxonomic levels （family, genus, and species） are driven by the same macro-environmental variables. In this study, seed plant elevational distribution data from the Lancang River Nature Reserve （Yunnan, China） were used to investigate spatial patterns in diversity and their environ- mental correlates, comparing across taxonomic levels. Environmental variables included energy availability, climate seasonality and environmental heterogeneity. All taxonomic levels （family, genus, and species） were found to have strong elevational richness gradients, with the strength of the gradient weakening at higher taxonomic levels. Spatial patterns in richness were explained by a combination of contemporary environmental variables and the mid-domain effect at all taxonomic levels. The independent effects of temperature- and precipitation-related variables were similar in explaining geographical patterns of family, genus and species richness. Energy, seasonality and heterogeneity variables influenced seed plant spatial richness at different taxonomic levels in similar ways.

关键词： Elevational diversity gradients Lancang River Nature Reserve Energy availability Climate seasonality Environmental heterogeneity

A two-step method to apply Xu–Payne multi-porosity model to estimate pore type from seismic data for carbonate reservoirs

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2020年第3期17卷 615-627页

作者： Hong-Bing Li Jia-Jia Zhang Sheng-Juan Cai Hao-Jie Pan Research Institute of Petroleum Exploration and Development Petrochina Company LimitedBeijing 100083China School of Geosciences China University of Petroleum(East China)Qingdao 266580China

Carbonate reservoirs exhibit strong heterogeneity in the distribution of pore types that can be quantitatively characterized by applying Xu–Payne multi-porosity ***,there are some prerequisites to this model the porosity and saturation need to be *** general,these application conditions are difficult to satisfy for seismic *** order to overcome this problem,we present a two-step method to estimate the porosity and saturation and pore type of carbonate reservoirs from seismic *** step one,the pore space of the carbonate reservoir is equivalent to a single-porosity system with an effective pore aspect ratio;then,a 3D rock-physics template(RPT)is established through the Gassmann’s equations and effective medium models;and then,the effective aspect ratio of pore,porosity and fluid saturation are simultaneously estimated from the seismic data based on 3D *** step two,the pore space of the carbonate reservoir is equivalent to a triple-porosity *** with the inverted porosity and saturation in the first step,the porosities of three pore types can be inverted from the seismic elastic *** application results indicate that our method can obtain accurate physical properties consistent with logging data and ensure the reliability of characterization of pore type.

关键词： Carbonate reservoirs Pore type Physical properties Rock-physics modeling Rock-physics inversion