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Optimal Feedback Control of Oil Reservoir Waterflooding Processes

International Journal of Automation and computing 2016年第1期13卷 73-80页

作者： A.S.Grema yi cao School of Energy Environment & Agrifood Cranfield University

Waterfiooding is a process where water is injected into an oil reservoir to supplement its natural pressure for increment in productivity. The reservoir properties are highly heterogeneous, its states change as production progresses which require varying injection and production settings for economic recovery. As water is injected into the reservoir, more oil is expected to be produced. There is also likelihood that water is produced in association with the oil. The worst case is when the injected water meanders through the reservoir, it bypasses pools of oil and gets produced, Therefore, any effort geared toward finding the optimal settings to maximize the value of this venture can never be over emphasized. Waterflooding can be formulated as an optimal control problem. However, traditional optimal control is an open-loop solution, hence cannot cope with various uncertainties inevitably existing in any practical systems. Reservoir models are highly uncertain. Its properties are known with some degrees of certainty near the well-bore region only. In this work, a novel data-driven approach for control variable （CV） selection was proposed and applied to reservoir waterflooding process for a feedback strategy resulting in optimal or near optimal operation. The results indicated that the feedback control method was close to optimal in the absence of uncertainty. The loss recorded in the value of performance index, net present value （NPV） was only 0.26%. Furthermore, the new strategy performs better than the open-loop optimal control solution when system/model mismatch was considered. The performance depends on the scale of the uncertainty introduced. A gain in NPV as high as 30.04% was obtained.

关键词： Oil reservoir management intelligent wells optimal control theory feedback control geological uncertainty.

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Phase-Division-Based Dynamic Optimization of Linkages for Drawing Servo Presses

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Chinese Journal of Mechanical Engineering 2017年第6期30卷 1426-1437页

作者： Zhi-gang Zhang Li-Ping Wang Yan-Ke cao JIER Machine-Tool Group Co. Ltd Department of Mechanical Engineering Tsinghua University

Existing linkage-optimization methods are designed for mechanical presses; few can be directly used for servo presses, so development of the servo press is limited. Based on the complementarity of linkage opti- mization and motion planning, a phase-division-based linkage-optimization model for a drawing servo press is established. Considering the motion-planning principles of a drawing servo press, and taking account of work rating and efficiency, the constraints of the optimization model are constructed. Linkage is optimized in two modes： use of either constant eccentric speed or constant slide speed in the work segments. The performances of optimized link- ages are compared with those of a mature linkage SL4- 2000A, which is optimized by a traditional method. The results show that the work rating of a drawing servo press equipped with linkages optimized by this new method improved and the root-mean-square torque of the servo motors is reduced by more than 10%. This research pro- vides a promising method for designing energy-saving drawing servo presses with high work ratings.

关键词： Drawing servo press Linkage optimization Phase-division Motion planning

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A microfluidic approach for synchronous and nondestructive study of the permeability of multiple oocytes

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Microsystems & Nanoengineering 2020年第1期6卷 694-705页

作者： Zhongrong Chen Kashan Memon Yunxia cao gang Zhao Department of Electronic Science and Technology University of Science and Technology of ChinaHefei 230027China Reproductive Medicine Center Department of Obstetrics and GynecologyThe First Affiliated Hospital of Anhui Medical UniversityHefei 230022China Anhui Province Key Laboratory of Reproductive Health and Genetics Anhui Provincial Engineering Technology Research Center for Biopreservation and Artificial OrgansAnhui Medical UniversityHefei 230022China

Investigation of oocyte membrane permeability plays a crucial role in fertility preservation,reproductive medicine,and reproductive ***,the commonly used methods have disadvantages such as high time consumption,low efficiency,and cumbersome data *** addition,the developmental potential of oocytes after measurement has not been fully validated in previous ***,oocytes can only maintain their best status in vitro within a very limited *** address these limitations,we developed a novel multichannel microfluidic chip with newly designed micropillars that provide feasible and repeatable oocyte *** osmotic responses of three oocytes at different or the same cryoprotectant(CPA)concentrations were measured simultaneously,which greatly improved the measurement ***,the CPA concentration dependence of mouse oocyte membrane permeability was ***,a neural network algorithm was employed to improve the efficiency and accuracy of data ***,analysis of fertilization and embryo transfer after perfusion indicated that the microfluidic approach does not damage the developmental potential of *** brief,we report a new method based on a multichannel microfluidic chip that enables synchronous and nondestructive measurement of the permeability of multiple oocytes.

关键词： approach fluid maintain

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Multi-layer Contribution Propagation Analysis for Fault Diagnosis

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International Journal of Automation and computing 2019年第1期16卷 40-51页

作者： Ruo-Mu Tan yi cao School of Water Energy and Environment Cranfield University College of Chemical and Biological Engineering Zhejiang University

The recent development of feature extraction algorithms with multiple layers in machine learning and pattern recognition has inspired many applications in multivariate statistical process monitoring. In this work, two existing multi-layer linear approaches in fault detection are reviewed and a new one with extra layer is proposed in analogy. To provide a general framework for fault diagnosis in succession, this work also proposes the contribution propagation analysis which extends the original definition of contribution of variables in multivariate statistical process monitoring. In fault diagnosis stage, the proposed contribution propagation analysis for multilayer linear feature extraction algorithms is compared with the fault diagnosis results of original contribution plots associated with single layer feature extraction approach. Plots of variable contributions obtained by the aforementioned approaches on the data sets collected from a simulated benchmark case study(Tennessee Eastman process) as well as an industrial scale multiphase flow facility are presented as a demonstration of the usage and performance of the contribution propagation analysis on multi-layer linear algorithms.

关键词： Process monitoring fault detection and diagnosis contribution plots feature extraction multivariate statistics

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The differentiability of solutions for elliptic equations which degenerate on part of the boundary of a convex domain

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Applied Mathematics(A Journal of Chinese Universities) 2018年第4期33卷 421-435页

作者： SONG Jia-xin cao yi Department of Mathematics and Information Science Shaanxi Normal University

In this paper,we study the differentiability of solutions on the boundary for equartions of type L;u=;u/x;+|x|;;u/y;=f（x,y）,where λ is an arbitrary positive number. By introducing a proper metric that is related to the elliptic operator L;, we prove the differentiability on the boundary when some well-posed boundary conditions are satisfied. The main difficulty is the construction of new barrier functions in this article.

关键词： elliptic equations convex domain differentiability

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Performance Modeling for Data Monitoring Services in Smart Grid: A Network Calculus Based Approach

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CSEE Journal of Power and Energy Systems 2020年第3期6卷 610-618页

作者： Junwei cao Yuxin Wan Haochen Hua gang Yang Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China College of Energy and Electrical Engineering Hohai UniversityNanjing 211100China

This paper focuses on solving the modeling issues of monitoring system service performance based on the network calculus ***,we formulate the service model of the smart grid monitoring ***,we derive the flow arrival curve based on the incremental process related ***,we develop flow arrival curves for the case of the incremental process being a fractional Gaussian process,and then we obtain the generalized Cauchy *** technical theorems related to network calculus are presented as our main ***,the variance of arrival flow for the continuous time case is *** that the incremental process of network flow is a Gaussian stationary process,and given the auto-correlation function of the incremental process with violation probability,the formula of the arrival curve is *** addition,the overall flow variance under the discrete time case is explicitly *** theoretical results are evaluated in smart grid *** indicate that the generalized Cauchy process outperforms the fractional Gaussian process for our considered problem.

关键词： Fractional Gaussian process generalized Cauchy process monitoring systems network calculus service performance

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Cascading failures in local-world evolving networks

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第10期9卷 1336-1340页

作者： Zhe-jing BAO yi-jia cao School of Electrical Engineering Zhejiang University Hangzhou 310027 China College of Electrical and Information Engineering Hunan University Changsha 410082 China

The local-world (LW) evolving network model shows a transition for the degree distribution between the exponential and power-law distributions, depending on the LW size. Cascading failures under intentional attacks in LW network models with different LW sizes were investigated using the cascading failures load model. We found that the LW size has a significant impact on the network's robustness against deliberate attacks. It is much easier to trigger cascading failures in LW evolving networks with a larger LW size. Therefore, to avoid cascading failures in real networks with local preferential attachment such as the Internet, the World Trade Web and the multi-agent system, the LW size should be as small as possible.

关键词： Complex network Local world (LW) Cascading failures Power-law Attack

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Forward and backward models for fault diagnosis based on parallel genetic algorithms

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第10期9卷 1420-1425页

作者： yi LIU ying LI yi-jia cao Chuang-xin GUO School of Electrical Engineering Zhejiang University Hangzhou 310027 China

In this paper, a mathematical model consisting of forward and backward models is built on parallel genetic algorithms (PGAs) for fault diagnosis in a transmission power system. A new method to reduce the scale of fault sections is developed in the forward model and the message passing interface (MPI) approach is chosen to parallel the genetic algorithms by global sin-gle-population master-slave method (GPGAs). The proposed approach is applied to a sample system consisting of 28 sections, 84 protective relays and 40 circuit breakers. Simulation results show that the new model based on GPGAs can achieve very fast computation in online applications of large-scale power systems.

关键词： Forward and backward models Fault diagnosis Global single-population master-slave genetic algorithms (GPGAs) Parallel computation

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Electrical Conductivity of Eclogite, Amphibolite and Garnet-Quartz-Mica Schist with Implications for the Conductivity in the Qiangtang Terrane of Northern Tibetan Plateau

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Journal of Earth Science 2020年第4期31卷 683-692页

作者： yi cao Xinzhuan Guo Jinxue Du State Key Laboratory of Geological Processes and Mineral Resources School of Earth SciencesChina University of GeosciencesWuhan 430074China Key Laboratory for High-Temperature and High-Pressure Study of the Earth's Interior Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China

Understanding the electrical conductivity of high pressure metamorphic rocks is essential to constrain the compositions in the subduction zone and continental crust. In this study, we calculated the electrical conductivity for such rocks sampled from the central Qiangtang metamorphic belt in the northern Tibetan Plateau. The results reveal that, when aqueous fluids are absent, the conductivity of meta-mafic rocks(e.g., eclogite and amphibolite) is strikingly higher than that of meta-felsic rocks(e.g., garnet-quartz-mica schist). The conductivity of eclogite decreases due to the enrichment of amphibole, but this effect is diminished when a critical degree of amphibolization is reached. Our calculated conductivity of eclogite and amphibolite differs greatly from the experimentally derived results for the eclogites from other localities, partly owing to the strong effects of different mineral assemblages and chemical compositions on the conduction mechanisms and efficiencies. However, the disparity of conductivity between our calculated and the previously measured results for a similar amphibole-rich eclogite sampled from the same locality suggests that trails of highly conductive rutile-ilmenite aggregates may contribute to the higher bulk-rock conductivity in the laboratory measurements. Moreover, since the calculated conductivity of eclogite and amphibolite is not high enough at the temperatures relevant to their metamorphic thermal condition, partial melts or aqueous fluids originated from the upwelling asthenosphere are more likely to explain the anomalously high electrical conductivity zones in magnetotelluric images in the Qiangtang terrane in the northern Tibetan Plateau.

关键词： electrical conductivity eclogite amphibolite felsic schist high pressure metamorphic rock

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Memristor based on two-dimensional titania nanosheets for multilevel storage and information processing

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Nano Research 2022年第9期15卷 8419-8427页

作者： gang cao Chao Gao Jingjuan Wang Jinling Lan Xiaobing Yan Key Laboratory of Brain-Like Neuromorphic Devices and Systems of Hebei Province College of Electron and Information EngineeringHebei UniversityBaoding 071002China

A huge amount of data requires the non-volatile memory(NVM)technology to exhibit large-capacity storage and fast calculation *** further solve the bottleneck of storage capacity and speed,nano-memristors based on two-dimensional(2D)layered materials are expected to realize *** study proposes the fabrication of an Ag/2D-TiOx/Pt high-performance memristor device based on the 2D titania nanosheet *** device demonstrates stable electrical characteristics under the direct current(DC)mode,including bipolar resistive switching(RS)behavior,multi-level memristive modes,and retention ***,it exhibits low switching voltage(0.42 V/–0.2 V),high R_(OFF)/R_(ON)resistance ratio(105),low switching power(10–9 W/10−5 W),and fast response *** importantly,the device realizes information encoding and decoding through a multi-level storage performed by different compliance *** devices are connected to the actual circuit to realize a storage function with information processing and programmable *** work provides a powerful platform for the 2D titania nanosheet application in NVM and information processing.

关键词： titania nanosheets memristor low power multi-level storage information processing

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