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Pressure transient characteristics of non-uniform conductivity fractured wells in viscoelasticity polymer flooding based on oil-water two-phase flow

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Petroleum Science 2024年第1期21卷 343-351页

作者： Yang Wang jia Zhang {1.-Long Yang Ze-Xuan Xu {1.-Qing Cheng National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China

Polymer flooding in fractured wells has been extensively applied in oilfields to enhance oil *** contrast to water,polymer solution exhibits non-Newtonian and nonlinear behavior such as effects of shear thinning and shear thickening,polymer convection,diffusion,adsorption retention,inaccessible pore volume and reduced effective ***,the flux density and fracture conductivity along the hydraulic fracture are generally non-uniform due to the effects of pressure distribution,formation damage,and proppant *** this paper,we present an oil-water two-phase flow model that captures these complex non-Newtonian and nonlinear behavior,and non-uniform fracture characteristics in fractured polymer *** hydraulic fracture is firstly divided into two parts:high-conductivity fracture near the wellbore and low-conductivity fracture in the far-wellbore section.A hybrid grid system,including perpendicular bisection(PEBI)and Cartesian grid,is applied to discrete the partial differential flow equations,and the local grid refinement method is applied in the near-wellbore region to accurately calculate the pressure distribution and shear rate of polymer *** combination of polymer behavior characterizations and numerical flow simulations are applied,resulting in the calculation for the distribution of water saturation,polymer concentration and reservoir *** with the polymer flooding well with uniform fracture conductivity,this non-uniform fracture conductivity model exhibits the larger pressure difference,and the shorter bilinear flow period due to the decrease of fracture flow ability in the far-wellbore *** field case of the fall-off test demonstrates that the proposed method characterizes fracture characteristics more accurately,and yields fracture half-lengths that better match engineering reality,enabling a quantitative segmented characterization of the near-wellbore section with high fracture conductivity and th

关键词： Polymer flooding Non-Newtonian fluid Non-uniform fracture conductivity Two-phase flow Pressure transient analysis

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AWeb Application Fingerprint Recognition Method Based on Machine Learning

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Computer Modeling in Engineering & Sciences 2024年第7期140卷 887-906页

作者： Yanmei shi Wei Yu Yanxia Zhao Yungang {1. School of Integrated Circuit Science and Engineering Tianjin University of TechnologyTianjin300382China College of International Business Zhejiang Yuexiu UniversityShaoxing312030China School of Public Administration Zhejiang Gongshang UniversityHangzhou310018China Tianjin Branch of National Computer Network Emergency Response Technical Team/Coordination Center of China Tianjin300100China

Web application fingerprint recognition is an effective security technology designed to identify and classify web applications,thereby enhancing the detection of potential threats and *** fingerprint recognition methods,which rely on preannotated feature matching,face inherent limitations due to the ever-evolving nature and diverse landscape of web *** response to these challenges,this work proposes an innovative web application fingerprint recognition method founded on clustering *** method involves extensive data collection from the Tranco List,employing adjusted feature selection built upon Wappalyzer and noise reduction through truncated SVD dimensionality *** core of the methodology lies in the application of the unsupervised OPTICS clustering algorithm,eliminating the need for preannotated *** transforming web applications into feature vectors and leveraging clustering algorithms,our approach accurately categorizes diverse web applications,providing comprehensive and precise fingerprint *** experimental results,which are obtained on a dataset featuring various web application types,affirm the efficacy of the method,demonstrating its ability to achieve high accuracy and broad *** novel approach not only distinguishes between different web application types effectively but also demonstrates superiority in terms of classification accuracy and coverage,offering a robust solution to the challenges of web application fingerprint recognition.

关键词： Web application fingerprint recognition unsupervised learning clustering algorithm feature extraction automated testing network security

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Microstructural characterization and mechanical properties of(TiC+TiB)/TA1. composites prepared by an in-situ synthesis method

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China Foundry 2024年第2期21卷 168-174页

作者： Zhi-yong Zhang jiao-jiao Cheng jia-qi Xie shi-bing Liu Kun shi Jun Zhao Shenyang Research Institute of Foundry Co. Ltd.CAMShenyang 110022China National Key Laboratory of Advanced Casting Technologies Shenyang 110022China

Titanium matrix composites reinforced with ceramic particles are considered a promising engineering material due to their combination of high specific strength,low density,and high *** this study,the TA1.-based composites reinforced with a volume fraction of 1.% to 25%(TiB+TiC)were prepared using powder metallurgy and casting *** characterization and phase constitution were examined using optical microscopy(OM),scanning electron microscopy(SEM),and X-ray diffraction(XRD).In addition,the microhardness,room temperature(RT)and high temperature(HT)tensile properties of the composites were *** revealed that the reinforcements are distributed uniformly even in the composites with a high volume of TiB and ***,as the volume fraction exceeds 1.%,TiB and TiC particles become coarsening and exhibit rod-like and dendritic-like *** increases gradually from 321.2 HV for the base alloy to a maximum of 473.3 HV as the reinforcement increases to 25vol.%.Tensile test results indicate that a reinforcement volume fraction above 20% is beneficial for enhancing tensile strength and yield strength at high temperatures,but it has an adverse effect on room temperature ***,if the reinforcement volume fraction is below 20%,it can improve high-temperature elongation when the temperature exceeds 600℃.

关键词： titanium matrix composites microstucture microhardness tensile properties in-situ synthesis

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Survey on performance of vertical slot and nature-like fishways at Angu hydropower station, Southwest China

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Water Science and Engineering 2024年第1期17卷 83-91页

作者： Jun-jian Sun jia-yue shi Qi Zhang Xiao-tao shi Jun-jun Tan PowerChina Huadong Engineering Corporation Limited Hangzhou 311122China Hubei International Science and Technology Cooperation Base of Fish Passage China Three Gorges UniversityYichang 443002China

To restore dam-blocked natural fish migratory passages,a growing number of artificial fishways have been built in water conservancy and hydropower projects in *** Angu hydropower station involved diverse important fish habitats in the lower reaches of the Daduhe River in Southwest ***,a vertical slot fishway(VSF)and a nature-like fishway(NLF)were built near the backwater area of the reservoir to connect the upstream and downstream *** and aquatic ecological surveys were conducted after the completion of the project to estimate the fish passing effect of the two *** results indicated that both fishways were in effective operation and could maintain the desired hydrodynamic conditions and be used by several local fish *** the survey,1.9 fish from 1. species and 1.1.fish from 1. species were captured by the traps in the VSF and NLF,respectively,while 1.63 fish from 27 species were found in the downstream *** species captured in the VSF were not found in the NLF,and vice versa,which implied the different preferences of ***,3789 signals including 2099 upward ones and 1.90 downward ones were monitored with an ultrasonic fish detector at the inlet of the *** findings revealed the characteristics of fish species observed in and near the fishways and provided valuable insights into the different fish passing capabilities of VSFandNLF.

关键词： Vertical slot fishway Nature-like fishway Aguatic ecological survey Fishwaymonitoring Statistical analysis

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Cognitive Jammers Assisted Covert Communication in Cognitive Radio Networks

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China Communications 2024年第9期21卷 75-89页

作者： Liu Changjun shi {1. Tie Zhuangzhuang Wang Yongchao The State Key Laboratory of Integrated Services Networks Xidian UniversityXi’an 710071China

In this work,we investigate the covert communication in cognitive radio(CR)networks with the existence of multiple cognitive jammers(CJs).Specifically,the secondary transmitter(ST)helps the primary transmitter(PT)to relay information to primary receiver(PR),as a reward,the ST can use PT's spectrum to transmit private information against the eavesdropper(Eve)under the help of one selected cognitive jammer(CJ).Meanwhile,we propose three jammer-selection schemes,namely,link-oriented jammer selection(LJS),min-max jammer selection(MMJS)and random jammer selection(RJS).For each scheme,we analyze the average covert throughput(ACT)and covert outage probability(COP).Our simulation results show that CJ is helpful to ST's covert communication,the expected minimum detection error probability and ACT can be significantly improved with the increase of false alarm of ***,the LJS scheme achieves best performance in ACT and COP,followed by RJS scheme,and MMJS scheme shows the worst performance.

关键词： cognitive jammer cognitive radio covert communication performance analysis

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An approximate analytical model for unconventional reservoir considering variable matrix blocks and simultaneous matrix depletion

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Petroleum Science 2024年第1期21卷 352-365页

作者： Kai-Xuan Qiu jia Li Dong Feng {1.-Ming Wei Gang Lei jiangmen Laboratory of Carbon Science and Technology Jiangmen529100GuangdongChina The Hong Kong University of Science and Technology(Guangzhou) Guangzhou511400GuangdongChina China University of Geosciences(Beijing) Beijing100083China China University of Petroleum(Beijing) Beijing102249China China University of Geosciences(Wuhan) Wuhan430074HubeiChina Shenzhen Research Institute China University of GeosciencesShenzhen518063GuangdongChina

In regard to unconventional oil reservoirs,the transient dual-porosity and triple-porosity models have been adopted to describe the fluid flow in the complex fracture *** has been proven to cause inaccurate production evaluations because of the absence of matrix-macrofracture *** addition,most of the existing models are solved analytically based on Laplace transform and numerical ***,an approximate analytical solution is derived directly in real-time space considering variable matrix blocks and simultaneous matrix *** simplify the derivation,the simultaneous matrix depletion is divided into two parts:one part feeding the macrofractures and the other part feeding the ***,a series of partial differential equations(PDEs)describing the transient flow and boundary conditions are constructed and solved analytically by ***,a relationship between oil rate and production time in real-time space is *** new model is verified against classical analytical *** the microfracture system and matrix-macrofracture communication is neglected,the result of the new model agrees with those obtained with the dual-porosity and triple-porosity model,***,the new model also has an excellent agreement with the numerical *** model is then applied to two actual tight oil wells completed in western Canada sedimentary *** identifying the flow regime,the solution suitably matches the field production data,and the model parameters are *** these output parameters,we can accurately forecast the production and even estimate the petrophysical properties.

关键词： Analytical solution Unconventional reservoir Variable matrix Simultaneous flow

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A new fabrication method for enhancing the yield of linear micromirror arrays assisted by temporary anchors

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Microsystems & Nanoengineering 2024年第3期10卷 169-180页

作者： Xingchen Xiao Ting Mao Yingchao shi Kui Zhou {1. Hao Yiting Yu Ningbo Institute of Northwestern Polytechnical University College of Mechanical EngineeringNorthwestern Polytechnical University710072 Xi’anChina Key Laboratory of Micro/Nano Systems for Aerospace(Ministry of Education) Shaanxi Province Key Laboratory of Micro and Nanoelectromechanical SystemsNorthwestern Polytechnical University710072 Xi’anChina

As one of the most common spatial light modulators,linear micromirror arrays(MMAs)based on microelectromechanical system(MEMS)processes are currently utilized in many ***,two crucial challenges exist in the fabrication of such devices:the adhesion of silicon microstructures caused by anodic bonding and the destruction of the suspended silicon film due to residual *** solve these issues,an innovative processing method assisted by temporary anchors is *** approach effectively reduces the span of silicon microstructures and improves the Euler buckling limit of the silicon ***,these temporary anchors are strategically placed within the primary etching areas,enabling easy removal without additional processing *** a result,we successfully achieved wafer-level,high-yield manufacturing of linear MMAs with a filling factor as high as 95.1..Demonstrating superior capabilities to those of original MMAs,our enhanced version boasts a total of 60 linear micromirror elements,each featuring a length-to-width ratio of 52.6,and the entire optical aperture measures 5 mm×6 *** linear MMA exhibits an optical deflection angle of 20.4°at 1.0 Vdc while maintaining exceptional deflection flatness and *** study offers a viable approach for the design and fabrication of thin-film MEMS devices with high yields,and the proposed MMA is promising as a replacement for digital micromirror devices(DMDs,by TI Corp.)in fields such as spectral imaging and optical communication.

关键词： mirror exceptional anodic

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Increase of chiral sensing ability in host-guest chemistry by magnetic anisotropy

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Science China Chemistry 2024年第8期67卷 2775-2782页

作者： jia-Liang Chen Bin Li Feng Yang Tiesheng {1. Xun-Cheng Su State Key Laboratory of Elemento-organic Chemistry Tianjin Key Laboratory of Biosensing and Molecular RecognitionCollege of ChemistryNankai UniversityTianjin 300071China College of Chemistry Chemical Engineering and Materials ScienceZaozhuang UniversityZaozhuang 277160China

Enantiomeric molecules generally play distinct functions in chemistry,biology,and *** physical and chemical properties of chiral analytes lay difficulty in discrimination and quantification of the *** report herein an efficient approach of increasing the chiral sensing ability ofβ-cyclodextrin(β-CD),a widely used host molecule,in the hostguest chemistry by magnetic anisotropy.A rigid and chiral lanthanide binding tag was attached to theβ-CD to amplify the changes of nuclear magnetic resonance(NMR)signals in the host-guest recognition *** installation of the paramagnetic lanthanide ion inβ-CD greatly enhances the enantiomeric discrimination up to 30-fold in comparison with the diamagneticβ-CD *** addition,the magnitude of the paramagnetic effects is tunable according to the diverse range of paramagnetic strength of the lanthanide *** reported method significantly increases the chiral sensing ability ofβ-CD,which can be applied to other host *** transferred paramagnetic effects,pseudocontact shifts(PCSs)and paramagnetic relaxation enhancements(PREs),from the host to the guest molecules,are valuable structural restraints to determine the absolute stereochemistry of the chiral *** strategy does not need modification of the analytes and is complementary to the reported analytical methods that rely on the functionalization of the chiral analytes.

关键词： chiral recognition nuclear magnetic resonance host-guest chemistry magnetic anisotropy lanthanide ions

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A direct electrochemical biosensor for rapid glucose detection based on nitrogen-doped carbon nanocages

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Rare Metals 2024年第5期43卷 2184-2192页

作者： Lan-Lan Li Yu Zhao Li-jia Pan jian-Bin Xu Yi shi College of Mechanical and Electrical Engineering Henan Agricultural UniversityZhengzhou 450002China School of Electronic Science and Engineering Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210093China Department of Electronic Engineering The Chinese University of HongKongHongkong 999077China

Given the increasing number of diabetic patients,rapid and accurate detection of glucose in body fluids is *** study developed a direct electrochemical biosensor for glucose based on nitrogen-doped carbon nanocages(NCNCs).NCNCs possess a large specific surface area of 1.95 m^(2)·g^(-1.,a high N atomic content of 9.37%and good biocompatibility,which is favorable for enzyme loading and electron *** surface average concentration of electroactive glucose oxidase on NCNCs was 2.82×1.^(-1.)mol·cm^(-2).The NCNC-based direct electrochemical biosensor exhibited a high sensitivity of 1..7μA·(mmol·L^(-1.)^(-1.·cm^(-2),rapid response time of 5 s and an impressive electron-transferrate constant(ks)of 1.87 s^(-1..Furthermore,we investigated an NCNC-based direct electron transfer(DET)biosensor for sweat glucose detection,which demonstrated tremendous promise for non-invasive wearable diabetes diagnosis.

关键词： Direct electron transfer(DET) Nitrogen-doped carbon nanocages(NCNCs) Glucose oxidase Biosensor

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Simultaneous Bulk-and Surface-initiated Living Polymerization Studied with a Heterogeneous Stochastic Reaction Model

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Chinese Journal of Polymer Science 2024年第3期42卷 364-372,I0008页

作者： jia-Shu Ma Zhi-Ning Huang jia-Hao Li Bang-Ping jiang Yan-Da Liao shi-Chen Ji Xing-Can Shen State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources(Ministry of Education of China)School of Chemistry and Pharmaceutical SciencesGuangxi Normal UniversityGuilin 541004China School of Computer Science and Engineering&School of Software Guangxi Normal UniversityGuilin 541004China

To better characterize the properties of surface-initiated polymers, simultaneous bulk-and surface-initiated polymerizations are usually carried out by assuming that the properties of the surface-initiated polymers resemble those of the bulk-initiated polymers. Through a Monte Carlo simulation using a heterogeneous stochastic reaction model, it was discovered that the bulk-initiated polymers exhibit a higher molecular weight and a lower dispersity than the corresponding surface-initiated polymers, which indicates that the equivalent assumption is invalid. Furthermore, the molecular weight distributions of the two types of polymers are also different, suggesting different polymerization mechanisms. The results can be simply explained by the heterogeneous distributions of reactants in the system. This study is helpful to better understand surface-initiated polymerization.

关键词： Surface-initiated polymerization Polymer brush Stochastic reaction model Heterogeneous polymerization Simultaneous polymerization

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