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Equidistance target-following controller for underactuated autonomous underwater vehicles

International Journal of Intelligent Computing and Cybernetics 2013年第2期6卷 108-125页

作者： behzad taheri Edmond Richer Department of Mechanical Engineering Southern Methodist UniversityDallasTexasUSA

Purpose–Autonomous Underwater Vehicles(AUVs)play a crucial role in marine biology research and oceanic natural resources *** most AUVs are underactuated they require sophisticated trajectory planning and tracking *** purpose of this paper is to develop a new method that allows an underactuated AUV to track a moving object while constraining the approach to a direction tangent to the path of the ***,the distance at which the AUV follows the target is constrained,reducing the probability of detection and unwanted behavior change of the ***/methodology/approach–First,a kinematic controller that generates a trajectory tangent to the path of the moving target is designed such that the AUV maintains a prescribed distance and approaches the target from *** a Lyapunov based method the stability of the kinematic controller is ***,a dynamic sliding mode controller is employed to drive the vehicle on the trajectory computed in the first ***–The kinematic and dynamic controllers are shown to be stable and robust against parameter uncertainty in the dynamic model of the *** of numerical simulations for equidistant tracking of a target on both smooth and discontinuous derivatives trajectories for a variety of relative initial positions and orientations are ***/value–The contribution of this research is development of a new method for path planning and tracking of moving targets for underactuated AUVs in the horizontal *** method allows control of both the direction of approach and the distance from a moving object.

关键词： Trajectories Tracking Programming and algorithm theory Underwater technology Controllers Path planning and trajectory tracking Autonomous underwater vehicles Nonlinear robust control

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Investigation of rock salt layer creep and its effects on casing collapse

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International Journal of Mining Science and Technology 2020年第3期30卷 357-365页

作者： S.Reza taheri Ali Pak Saeed Shad behzad Mehrgini Meisam Razifar Civil Engineering Department Sharif University of TechnologyTehranIran Upstream Petroleum Research Institute Sharif University of TechnologyTehranIran Chemical and Petroleum Engineering Department Sharif University of TechnologyTehranIran Kish Petroleum Engineering Company TehranIran Folowrd Industrial Projects Company TehranIran

Casing collapse is one of the costly incidents in the oil industry. In the oil fields of southwest Iran, most casing collapses have occurred in Gachsaran formation, and the halite rock salt layer in this formation may be the main cause for these incidents because of its peculiar creep behavior. In this research, triaxial creep experiments have been conducted on Gachsaran salt samples under various temperatures and differential stresses. The main purpose was to determine the creep characteristics of Gachsaran rock salt,and to examine the role of creep in several casing collapses that occurred in this formation. Results indicated that the halite rock salt of Gachsaran formation basically obeys the power law;however, its creep parameters are quite different from other halite rocks elsewhere. The time-dependent creep of Gachsaran rock salt exhibits strong sensitivity to temperature change;however, its sensitivity to variation of differential stress is rather low. The numerical simulation of the rock salt creep in a real oil well demonstrated the importance of creep and reservoir conditions on the safety factor of the tubing related to casing collapse.

关键词： Rock salt Gachsaran formation Creep Power law Casing collapse Numerical simulation

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自体血清滴眼液对屈光性角膜切削术后角膜上皮愈合的影响（英文）

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国际眼科杂志 2019年第4期19卷 527-532页

作者： Ali Mostafaei behzad Fallahi Motlagh Nazli taheri Siamak Nejatbakhsh 大不里士医科大医学研究中心眼科伊朗*** 大不里士医科大Nikoukari眼科医院伊朗***

目的:研究自体血清滴眼液对屈光性角膜切削术(PRK)后角膜上皮愈合的影响。方法:本研究共纳入20例40眼近视及近视散光患者,其中男性9例,女性11例。每例患者随机选取一眼作为研究组应用20%含自体血清的人工泪液,另一眼为对照组应用常规人... 详细信息

目的:研究自体血清滴眼液对屈光性角膜切削术(PRK)后角膜上皮愈合的影响。方法:本研究共纳入20例40眼近视及近视散光患者,其中男性9例,女性11例。每例患者随机选取一眼作为研究组应用20%含自体血清的人工泪液,另一眼为对照组应用常规人工泪液。PRK术中,40眼均于角膜表面居中放置直径8 mm的酒精储槽, 20%的酒精作用20s。术后每天观察直到角膜上皮愈合后,分别于1mo,6mo,12mo进行随访。上皮愈合时间为主要观察指标,并记录裸眼视力(UCVA),显然验光和混浊度。结果:两组间术前小瞳检影结果无明显差异。术后1d,2d,3d,研究组平均疼痛评分均显著低于对照组(P<0.05)。术后1d,3d,研究组的平均水平和垂直上皮缺损低于对照组(P<0.05)。研究组上皮完全愈合的平均时间比对照组短约0.7d(3.15±0.366d vs 3.85±0.587d,P=0.00)。结论:研究表明,应用自体血清滴眼液,通过加速角膜上皮愈合和减轻疼痛,从而缩短视力恢复时间,降低屈光性角膜切削术术后不适、混浊度和感染风险。

关键词：角膜自体血清屈光角膜切除术上皮愈合

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Assessment of depth of anesthesia using principal component analysis

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Journal of Biomedical Science and Engineering 2009年第1期2卷 9-15页

作者： Mina taheri behzad Ahmadi Rassoul Amirfattahi Mojtaba Mansouri Digital Signal Processing Research Lab Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156-83111 Iran Medical Image and Signal Processing Research Center Isfahan University of Medical Sciences Isfahan Iran. Correspondence should be addressed to Mina Taheri

A new approach to estimating level of uncon-sciousness based on Principal Component Analysis (PCA) is proposed. The Electroen-cephalogram (EEG) data was captured in both Intensive Care Unit (ICU) and operating room, using different anesthetic drugs. Assuming the central nervous system as a 20-tuple source, window length of 20 seconds is applied to EEG. The mentioned window is considered as 20 nonoverlapping mixed-signals (epoch). PCA algorithm is applied to these epochs, and larg-est remaining eigenvalue (LRE) and smallest remaining eigenvalue (SRE) were extracted. Correlation between extracted parameters (LRE and SRE) and depth of anesthesia (DOA) was measured using Prediction probability (PK). The results show the superiority of SRE than LRE in predicting DOA in the case of ICU and isoflurane, and the slight superiority of LRE than SRE in propofol induction. Finally, a mixture model containing both LRE and SRE could predict DOA as well as Relative Beta Ratio (RBR), which expresses the high capability of the proposed PCA based method in estimating DOA.

关键词： Bispectral Index Depth of Anesthesia Eignevalue Decomposition Principal Component Analysis

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