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Calculating frictional force with considering material microstructure and potential on contact surfaces

XU Zhongming, HUANG Ping

《机械工程前沿（英文）》 2007年第2卷第4期页码 474-477 doi: 10.1007/s11465-007-0082-y

摘要： A method based on the energy dissipation mechanism of an Independent Oscillator model is used to calculate the frictional force and the friction coefficient of interfacial friction. The friction work is calculated with considering the potential change of contact surfaces during sliding. The potential change can be gained by a universal adhesive energy function. The relationships between frictional force and parameters of a tribo-system, such as surface energy and microstructure of interfacial material, are set up. The calculation results of the known experimental data denote that the frictional force is nearly proportional to the surface energy of the material, nearly inversely proportional to the scaling length, and independent of the lattice constant. The results agree with that of adhesion friction equations. They also agree with the experimental results performed with an atomic-force microscope under the ultra high vacuum condition.

关键词： coefficient dissipation mechanism universal adhesive interfacial Independent Oscillator

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Design and simulation of a standing wave oscillator based PLL

Wei ZHANG,You-de HU,Li-rong ZHENG

《信息与电子工程前沿（英文）》 2016年第17卷第3期页码 258-264 doi: 10.1631/FITEE.1500210

摘要： A standing wave oscillator (SWO) is a perfect clock source which can be used to produce a high frequency clock signal with a low skew and high reliability. However, it is difficult to tune the SWO in a wide range of frequencies. We introduce a frequency tunable SWO which uses an inversion mode metal-oxide-semiconductor (IMOS) field-effect transistor as a varactor, and give the simulation results of the frequency tuning range and power dissipation. Based on the frequency tunable SWO, a new phase locked loop (PLL) architecture is presented. This PLL can be used not only as a clock source, but also as a clock distribution network to provide high quality clock signals. The PLL achieves an approximately 50% frequency tuning range when designed in Global Foundry 65 nm 1P9M complementary metal-oxide-semiconductor (CMOS) technology, and can be used directly in a high performance multi-core microprocessor.

关键词： Standing wave oscillator (SWO) Clock distribution Phase locked loop (PLL) Varactor

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Maximum independent set in planning freight railway transportation

Gainanov Damir N., Mladenovic NENAD, Rasskazova V. A.

《工程管理前沿（英文）》 2018年第5卷第4期页码 499-506 doi: 10.15302/J-FEM-2018031

摘要：

This work is devoted to the problem of planning of freight railway transportation. We define a special conflict graph on the basis of a set of acceptable train routes. The investigation aims to solve the classical combinatorial optimization problem in relation to the maximum independent set of vertices in undirected graphs. The level representation of the graph and its tree are introduced. With use of these constructions, the lower and upper bounds for the number of vertices in the maximum independent set are obtained.

关键词： independent set algorithm planning of transportation two-sided estimate

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Independent cover meshless particle method for complex geotechnical engineering

Jianqiu WU, Yongchang CAI

《结构与土木工程前沿（英文）》 2018年第12卷第4期页码 515-526 doi: 10.1007/s11709-017-0428-4

摘要： A new Independent Cover Meshless Particle (ICMP) method is proposed for the analysis of complex geotechnical engineering. In the ICMP method, the independent rectangular cover regardless of the shape of the analysis model is employed as the influence domain of each discrete node, the general polynomial is employed as the meshless interpolation function of the independent nodal cover, and the Cartesian Transformation Method (CTM) is used for the numerical integration of the nodal covers cut by material interfaces, joints, cracks and faults. The present method has a simple formulation and a low computational cost, and is easy for the numerical analysis and modeling of complex geotechnical engineering. Several typical numerical examples are presented to demonstrate the accuracy and robustness of the proposed method.

关键词： meshless method particle method independent cover CTM geotechnical engineering

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自主开发——强国之道

金履忠

《中国工程科学》 2005年第7卷第7期页码 1-6

摘要：

论证了自主开发在政治、军事、经济、安全、科技等方面的重大意义。建议用10～15年的时间，使我国的绝大多数产业具备自主开发和国际竞争能力；分析了实现这个目标是完全可能的。最后提出了应在思想观念、精神状态、法律法规、政策、体制、宣传舆论等方面创造有利于自主开发的环境。

关键词：自主开发的重要性实现的目标可能性营造自主开发的环境

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Fast removal of ocular artifacts from electroencephalogram signals using spatial constraint independent

Bang-hua YANG,Liang-fei HE,Lin LIN,Qian WANG

《信息与电子工程前沿（英文）》 2015年第16卷第6期页码 486-496 doi: 10.1631/FITEE.1400299

摘要： Ocular artifacts cause the main interfering signals within electroencephalogram (EEG) signal measurements. An adaptive filter based on reference signals from an electrooculogram (EOG) can reduce ocular interference, but collecting EOG signals during a long-term EEG recording is inconvenient and uncomfortable for the subject. To remove ocular artifacts from EEG in brain-computer interfaces (BCIs), a method named spatial constraint independent component analysis based recursive least squares (SCICA-RLS) is proposed. The method consists of two stages. In the first stage, independent component analysis (ICA) is used to decompose multiple EEG channels into an equal number of independent components (ICs). Ocular ICs are identified by an automatic artifact detection method based on kurtosis. Then empirical mode decomposition (EMD) is employed to remove any cerebral activity from the identified ocular ICs to obtain exact artifact ICs. In the second stage, first, SCICA applies exact artifact ICs obtained in the first stage as a constraint to extract artifact ICs from the given EEG signal. These extracted ICs are called spatial constraint ICs (SC-ICs). Then the RLS based adaptive filter uses SC-ICs as reference signals to reduce interference, which avoids the need for parallel EOG recordings. In addition, the proposed method has the ability of fast computation as it is not necessary for SCICA to identify all ICs like ICA. Based on the EEG data recorded from seven subjects, the new approach can lead to average classification accuracies of 3.3% and 12.6% higher than those of the standard ICA and raw EEG, respectively. In addition, the proposed method has 83.5% and 83.8% reduction in time-consumption compared with the standard ICA and ICA-RLS, respectively, which demonstrates a better and faster OA reduction.

关键词： Ocular artifacts Electroencephalogram (EEG) Electrooculogram (EOG) Brain-computer interface (BCI) Spatial constraint independent component analysis based recursive least squares (SCICA-RLS)

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Topology-independent end-to-end learning model for improving the voltage profile in microgrids-integrated

《能源前沿（英文）》 2023年第17卷第2期页码 211-227 doi: 10.1007/s11708-022-0847-3

摘要： With multiple microgrids (MGs) integrated into power distribution networks in a distributed manner, the penetration of renewable energy like photovoltaic (PV) power generation surges. However, the operation of power distribution networks is challenged by the issues of multiple power flow directions and voltage security. Accordingly, an efficient voltage control strategy is needed to ensure voltage security against ever-changing operating conditions, especially when the network topology information is absent or inaccurate. In this paper, we propose a novel data-driven voltage profile improvement model, denoted as system-wide composite adaptive network (SCAN), which depends on operational data instead of network topology details in the context of power distribution networks integrated with multiple MGs. Unlike existing studies that realize topology identification and decision-making optimization in sequence, the proposed end-to-end model determines the optimal voltage control decisions in one shot. More specifically, the proposed model consists of four modules, Pre-training Network and modified interior point methods with adversarial networks (Modified IPMAN) as core modules, and discriminator generative adversarial network (Dis-GAN) and Volt convolutional neural network (Volt-CNN) as ancillary modules. In particular, the generator in SCAN is trained by the core modules in sequence so as to form an end-to-end mode from data to decision. Numerical experiments based on IEEE 33-bus and 123-bus systems have validated the effectiveness and efficiency of the proposed method.

关键词： end-to-end learning microgrids voltage profile improvement generative adversarial network

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Intra-abdominal hypertension is an independent cause of acute renal failure after orthotopic liver transplantation

SHU Ming, PENG Chenghong, CHEN Hao, SHEN Boyong, ZHOU Guangwen, SHEN Chuan, LI Hongwei

《医学前沿（英文）》 2007年第1卷第2期页码 167-172 doi: 10.1007/s11684-007-0031-5

摘要： An independent association between acute renal failure (ARF) and intra-abdominal hypertension (IAH) after liver transplantation has not been established previously. The aim of this retrospective study was to understand the role of IAH as an independent risk factor for ARF in the early postoperative period. This study involved 62 subjects who underwent liver transplantation. Intra-abdominal pressure (IAP) was measured in the first three days after surgery by using the urinary bladder technique. An IAP of at least 20 mmHg per day was defined as IAH. Clinical parameters between group IAH and group NO-IAH were compared in terms of the incidence of ARF, blood creatinine levels, blood urea nitrogen (BUN) levels, urine volume per hour and glomerular filtration gradient (GFG). Hemodynamic variations were recorded in the first three postoperative days between group ARF and group NO-ARF. The perioperative suspected risk factors of ARF were determined for statistical evaluation using correlation coefficients and logistic regression analysis. In group IAH, 45.8% patients developed ARF as against 7.9% in group NO-IAH; GFG was significantly lower at 0 72 h after surgery; and blood creatinine levels, BUN levels, urine volume per hour were significantly different at 24 72 h after surgery compared with group NO-IAH. The patients with ARF were not significantly different from those without ARF in terms of central venous pressure, pulmonary artery pressure and mean arterial pressure (MAP) in the first three postoperative days despite a significant increase in heart rate at 24 72h after operation. Postoperative IAH, intraoperative MAP and intraoperative blood transfusion volume of more than 15 U were found to be independent risk factors for ARF. IAH impaired renal function and was an independent risk factor for ARF after liver transplantation. Routine measurement should be taken to monitor IAP every eight hours postoperatively.

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G protein-coupled receptor LGR6 is an independent risk factor for colon adenocarcinoma

Wenjing Wang, Shigang Ding, Hejun Zhang, Jun Li, Jun Zhan, Hongquan Zhang

《医学前沿（英文）》 2019年第13卷第4期页码 482-491 doi: 10.1007/s11684-018-0633-0

摘要： LGR6 is a member of the G protein-coupled receptor family that plays a tumor-suppressive role in colon cancer. However, the relationship between LGR6 expression in patients and clinicopathological factors remains unclear. This study aimed to clarify whether the expression level of LGR6 is correlated with colon adenocarcinoma progression. Immunohistochemistry was used to detect LGR6 expression in colon adenoma tissues ( = 21), colon adenocarcinoma tissues ( = 156), and adjacent normal tissues ( = 124). The expression levels of LGR6 in colon adenoma and adenocarcinoma were significantly higher than those in normal colon epithelial tissues ( <0.001). Low LGR6 expression predicted a short overall survival in patients with colon adenocarcinoma (log-rank test, = 0.016). Univariate and multivariate survival analyses showed that, in addition to N and M classification, LGR6 expression served as an independent prognostic factor. Thus, low expression of LGR6 can be used as an independent prognostic parameter in patients with colon adenocarcinoma.

关键词： LGR6 colon adenocarcinoma immunohistochemistry prognosis

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p53 functional activation is independent of its genotype in five esophageal squamous cell carcinoma cell

Junfang JI, Kun WU, Min WU, Qimin ZHAN,

《医学前沿（英文）》 2010年第4卷第4期页码 412-418 doi: 10.1007/s11684-010-0260-x

摘要： mutations have been found in many esophageal squamous cell carcinoma (ESCC) clinical specimens and cell lines. We reasoned that functional inactivation of wild-type or the functional activation of mutant-type might exist in these specimens and cell lines. In this study, we identified the correlation between p53 functional activation and its genotype in five different ESCC cell lines. To examine the potential p53 activation in a certain ESCC cell line, DNA damage methods including X-ray exposure and cisplatin treatment were employed to treat cells. Further, the expression of p53 protein and four transcripts of well-known p53 target genes were investigated using Western blot and reverse transcription-polymerase chain reaction (RT-PCR) after cell exposure to DNA damage. The results showed that in KYSE 30 cell line with mutant and KYSE 150 with wild-type , p53 could be activated by DNA damages. However, p53 could not be activated following the DNA damages in YES 2 with wild-type , KYSE 70 with mutant , and EC9706 with unknown genotype. All our data indicated that p53 function in certain cells is not closely correlated with its genotype. To judge p53 function in a particular cell line, it is important to examine the p53 functional activation, but not to simply rely on the genotype.

关键词： p53 esophageal squamous cell carcinoma DNA damage

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Independent continuous and mapping method of structural topology optimization based on the global stress

Yunkang SUI, Jili FENG, Hongling YE, Xirong PENG,

《机械工程前沿（英文）》 2010年第5卷第2期页码 130-142 doi: 10.1007/s11465-010-0011-3

摘要： There are three difficulties in topology optimization of continuum structures. 1) The topology under multiple load case is more difficult to be optimized than under single load case, because the former becomes a multiple objective based on compliance objective functions. 2) With local constraints, such as an elemental stress limit, the topology is more difficult to be solved than with global constraints, such as the displacement or frequency limits, because the sensitivity analysis of the former has very expensive computation. 3) With the phenomenon of load illness, which is similar with stiffness illness in the structural analysis, it is not easy to get the reasonable final topological structure, because it is difficult to consider different influences between the loads with small forces and big forces, and some topology paths of transferring small forces may disappear during the iteration process. To overcome difficulties above, four measures are adopted. 1) Topology optimization model is established by independent continuous mapping (ICM) method. 2) Based on the von Mises strength theory, all elements’ stress constraints are transformed into a structural energy constraint. 3) The phenomenon of load illness is divided to classify into three cases. 4) A strategy based on strain energy is proposed to adopt ICM method with stress globalization, and the problems of the above mentioned three cases of load illness are solved in terms of different complementary approaches. Several numerical examples show that the topology path of transferring forces can be obtained more easily by substituting global strain energy constraints for local stresses constraints, and the problem of load illness can be solved well by the weighting method that takes the structural energy as a weighting coefficient.

关键词： independent continuous mapping (ICM) method global stresses constraints topology optimization continuum structure load illness

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nanotubes encapsulating M(Co, Fe)-Ni alloy for electrochemical production of syngas with potential-independent

《化学科学与工程前沿（英文）》 2022年第16卷第4期页码 498-510 doi: 10.1007/s11705-021-2082-6

摘要： The electrochemical conversion of CO₂-H₂O into CO-H₂ using renewable energy is a promising technique for clean syngas production. Low-cost electrocatalysts to produce tunable syngas with a potential-independent CO/H₂ ratio are highly desired. Herein, a series of N-doped carbon nanotubes encapsulating binary alloy nanoparticles (M_xNi-NCNT, M= Fe, Co) were successfully fabricated through the co-pyrolysis of melamine and metal precursors. The M_xNi-NCNT samples exhibited bamboo-like nanotubular structures with a large specific surface area and high degree of graphitization. Their electrocatalytic performance for syngas production can be tuned by changing the alloy compositions and modifying the electronic structure of the carbon nanotube through the encapsulated metal nanoparticles. Consequently, syngas with a wide range of CO/H₂ ratios, from 0.5:1 to 3.4:1, can be produced on M_xNi-NCNT. More importantly, stable CO/H₂ ratios of 2:1 and 1.5:1, corresponding to the ratio to produce biofuels by syngas fermentation, could be realized on Co₁Ni-NCNT and Co₂Ni-NCNT, respectively, over a potential window of –0.8 to –1.2 V versus the reversible hydrogen electrode. Our work provides an approach to develop low-cost and potential-independent electrocatalysts to effectively produce syngas with an adjustable CO/H₂ ratio from electrochemical CO₂ reduction.

关键词： electrochemical reduction of CO₂ syngas N-doped carbon nanotubes encapsulated alloy nanoparticles CO/H₂ ratio

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磁控微型机器人的选择性与独立控制——综述 Review

王敏, 吴天一, 刘锐, 张焯然, 刘军

《工程（英文）》 2023年第24卷第5期页码 21-38 doi: 10.1016/j.eng.2023.02.011

摘要：

磁驱动方法具有无线连接和高安全性的特点，是一种常见的微型机器人驱动技术，适用于微流体操作以及医疗微型机器人导航等应用。然而，由于微型机器人或被驱动的目标暴露在同一片磁场环境中，使得选择性地控制单个机器人或多个目标中的某一部分变得具有挑战性。本文回顾了磁场驱动的多微型机器人或多关节微型机器人系统的选择性和独立控制方法的最新进展。这些选择性和独立的控制方法将全局磁场解码为特定配置，用于多个微型机器人的独立驱动。这些方法包括将机器人设计成具有与众不同的物理属性或者在工作空间中的不同位置产生性质各异的磁场。对选定目标的独立控制使多个微型机器人能够有效协作以完成更复杂的操作。本文从一个独特的视角来解释如何在磁场中操纵单个微型机器人以在小尺度机器人中实现高水平的群体智能，这有助于加速微型机器人技术在现实生活中应用的转化和发展。

关键词：微型机器人磁性机器人独立控制选择性控制机器人微操作

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Application of fractal theory to unsaturated soil mechanics

XU Yongfu, TONG Lixin

《结构与土木工程前沿（英文）》 2007年第1卷第4期页码 411-421 doi: 10.1007/s11709-007-0056-5

摘要： The mechanical properties of unsaturated soils are a function of the saturation degree or matric suction, and can be obtained based on currently available procedures. However, each procedure has its limitations and consequently, care should be taken in the selection of a proper procedure. The fractal approach seems to be a potentially useful tool to describe hierarchical systems and is suitable to model the structure and hydraulic properties of unsaturated soils. In this paper, the soil-water characteristics, unsaturated hydraulic conductivity function, unsaturated shear strength, swelling deformation and compression were derived from the fractal model for the pore-size distribution, and were expressed by only two independent physical parameters, the fractal dimension and the air entry value. The predictions of the proposed soil-water characteristics, unsaturated hydraulic conductivity, unsaturated shear strength, swelling deformation and compression were in good agreement with published experimental data. Comparisons between the experimental results of unsaturated hydraulic conductivity and the predictions of the both fractal model and the van Genuchten-Mualem model were also performed, and it was found that the predictions of the fractal model were better than that of the van Genuchten-Mualem model.

关键词： selection soil-water independent physical unsaturated strength