检索结果-内蒙古大学图书馆

Optimizing train operational plan in an urban rail corridor based on the maximum headway function

TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES 2017年 74卷 51-80页

作者： Shi, Feng Zhao, Shuo Zhou, Zhao Wang, Pu Bell, Michael G. H. Cent S Univ Sch Traff & Transportat Engn Changsha 410075 Hunan Peoples R China Hisense Transtech Co Ltd Hisense Grp Qingdao 266071 Shandong Peoples R China Univ Sydney Inst Transport & Logist Studies Sydney NSW 2006 Australia

The train operational plan (TOP) plays a crucial role in the efficient and effective operation of an urban rail system. We optimize the train operational plan in a special network layout, an urban rail corridor with one terminal yard, by decomposing it into two sub-problems, i.e., the train departure profile optimization and the rolling stock circulation optimization. The first sub-problem synthetically optimizes frequency setting, timetabling and the rolling stock circulation at the terminal without a yard. The maximum headway function is generated to ensure the service of the train operational plan without considering travel demand, then we present a model to minimize the number of train trips, and design a heuristic algorithm to maximize the train headway. On the basis of a given timetable, the rolling stock circulation optimization only involves the terminal with a yard. We propose a model to minimize the number of trains and yard-station runs, and an algorithm to find the optimal assignment of train-trip pair connections is designed. The computational complexities of the two algorithms are both linear. Finally, a real case study shows that the train operational plan developed by our approach enables a better match of train headway and travel demand, and reduces the operational cost while satisfying the requirement of the level of service. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Urban rail corridor Train operational plan Maximum headway function Time-varying demand optimization algorithm

来源：评论

学校读者我要写书评

暂无评论

Influence of of Lode angle on modelling of void closure in hot metal forming processes

引用

FINITE ELEMENTS IN ANALYSIS AND DESIGN 2017年 126卷 13-25页

作者： Chbihi, A. Bouchard, P. -O. Bernacki, M. Munoz, D. Pino Mines ParisTech CEMEF Ctr Misee Forme Mat CNRS UMR 7635 CS 102071 Rue Claude Daunesse F-06904 Sophia Antipolis France

The presence of voids after casting processes of large metal workpieces requires the use of adapted hot metal forming processes to deliver sound products. Yet, there is at present a lack of knowledge regarding void closure mechanisms and there is no reliable model that can accurately predict void closure. The main aim of this work is to develop a highly accurate mean field model able to predict the evolution of the voids volume after each forming stage. This proposed model is accounting for both stress triaxiality ratio T-x, and Lode angle theta in order to override the hypothesis of axisymmetric loading, which is generally considered in the existing models handling void closure in the literature. Based on an advanced multiscale approach, this model also accounts for voids shape and orientation. An optimization method, using a database of explicit RVE simulations, is developed in order to calibrate the new proposed model. Several void morphological parameters and an industrial range of mechanical loading parameters are analyzed regarding void closure. The proposed mean field model is validated by comparison with explicit full field simulations and with a recent pre-existing mean field model, named Cicaporol model hereafter (Saby et al., 2015 [19]). In comparison with Cicaporol, the new model, named Cicaporo2 hereafter, uses less constants and is more accurate.

关键词： Void closure Mean field model Mesoscale optimization algorithm Lode angle

来源：评论

学校读者我要写书评

暂无评论

A Class of 1-Bit Multi-Step Look-Ahead Σ - Δ Modulators

引用

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS 2017年第1期64卷 24-37页

作者： Basetas, Charis Orfanos, Thanasis Sotiriadis, Paul P. Natl Tech Univ Athens Heroon Polytechniou 9 Zografos 15780 Greece

Digital Multi-Step Look-Ahead (MSLA) 1-bit Sigma-Delta modulators are introduced. They improve upon the stability and noise shaping characteristics of conventional 1-bit Sigma-Delta modulators by minimizing quantization error metrics of the current and future output samples. The mathematical model of the proposed MSLA modulators is analyzed. It is shown that the MSLA modulators are equivalent to a system of conventional Sigma-Delta modulators in parallel, but with a common multi-input 1-bit quantizer instead of a typical one. The properties of this multiinput quantizer are studied and the transfer functions of the MSLA modulators are derived. Simulation results are presented demonstrating the advantages of the MSLA modulators over conventional 1-bit Sigma-Delta ones in a number of applications. A parametric hardware architecture of the MSLA modulators is presented offering an adjustable trade-off between performance and hardware complexity based on the number of look-ahead steps. Finally, a FPGA implementation of a MSLA modulator is presented along with simulation results.

关键词： 1-bit quantization all-digital DAC look-ahead modulator noise shaping optimization algorithm sigma-delta

来源：评论

学校读者我要写书评

暂无评论

A minimized falling damage method for humanoid robots

引用

INTERNATIONAL JOURNAL OF ADVANCED ROBOTIC SYSTEMS 2017年第5期14卷

作者： Li, Qingqing Chen, Xuechao Zhou, Yuhang Yu, Zhangguo Zhang, Weimin Huang, Qiang Beijing Inst Technol Sch Mechatron Engn Intelligent Robot Inst 5 South Zhongguancun St Beijing 100081 Peoples R China Minist Educ Int Joint Res Lab Biomimet Robots & Syst Beijing Peoples R China Minist Educ Key Lab Biomimet Robots & Syst Beijing Peoples R China

In order to better adapt to human living environment for improving the ability of serving people on various occasions, humanoid robots need to prevent themselves from being severely damaged during falling backward. In this article, we have study the law of human falling motion with a motion capture system and propose a minimized falling damage method for humanoid robots. Falling backward is divided into two phases: the falling phase and the touchdown phase. The parametric optimal strategy based on inverted pendulum with flywheel is used to plan the motion of robot in the first phase to reduce the impact. In the second phase, to prevent the robot from bouncing and rolling over, the heuristic strategy including the best ratio of leg length inspired by biomechanical is adopted. The experiments have been tested on the BIT Humanoid Robot 6 prototype platform and the presented method has been validated.

关键词： Humanoid robots falling backward optimization algorithm inverted pendulum

来源：评论

学校读者我要写书评

暂无评论

Computational model for vitamin D deficiency using hair mineral analysis

引用

COMPUTATIONAL BIOLOGY AND CHEMISTRY 2017年 70卷 198-210页

作者： Hassanien, Aboul Ella Tharwat, Alaa Own, Hala S. Cairo Univ Fac Comp & Informat Cairo Egypt Suez Canal Univ Fac Engn Ismailia Egypt Frankfurt Univ Appl Sci Fac Comp Sci & Engn D-60318 Frankfurt Germany Sci Res Grp Egypt Cairo Egypt Natl Res Inst Astron & Geophys Dept Solar & Space Res El Marsad StPOB 11421 Helwan Egypt

Vitamin D deficiency is prevalent in the Arabian Gulf region, especially among women. Recent studies show that the vitamin D deficiency is associated with a mineral status of a patient. Therefore, it is important to assess the mineral status of the patient to reveal the hidden mineral imbalance associated with vitamin D deficiency. A well-known test such as the red blood cells is fairly expensive, invasive, and less informative. On the other hand, a hair mineral analysis can be considered an accurate, excellent, highly informative tool to measure mineral imbalance associated with vitamin D deficiency. In this study, 118 apparently healthy Kuwaiti women were assessed for their mineral levels and vitamin D status by a hair mineral analysis (HMA). This information was used to build a computerized model that would predict vitamin D deficiency based on its association with the levels and ratios of minerals. The first phase of the proposed model introduces a novel hybrid optimization algorithm, which can be considered as an improvement of Bat algorithm (BA) to select the most discriminative features. The improvement includes using the mutation process of Genetic algorithm (GA) to update the positions of bats with the aim of speeding up convergence;thus, making the algorithm more feasible for wider ranges of real-world applications. Due to the imbalanced class distribution in our dataset, in the second phase, different sampling methods such as Random Under-Sampling, Random Over-Sampling, and Synthetic Minority Oversampling Technique are used to solve the problem of imbalanced datasets. In the third phase, an AdaBoost ensemble classifier is used to predicting the vitamin D deficiency. The results showed that the proposed model achieved good results to detect the deficiency in vitamin D. (C) 2017 Elsevier Ltd. All rights reserved.

关键词： Vitamin D deficiency AdaBoost classifier Classification Bat algorithm (BA) Genetic algorithm (GA) optimization algorithm Imbalanced data Random sampling

来源：评论

学校读者我要写书评

暂无评论

Leveraging Social Communities for Optimizing Cellular Device-to-Device Communications

引用

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2017年第1期16卷 551-564页

作者： Alim, Md Abdul Pan, Tianyi Thai, My T. Saad, Walid Univ Florida Dept Comp & Informat Sci & Engn Gainesville FL 32611 USA Ton Duc Thang Univ Fac Informat Technol Div Algorithms & Technol Networks Anal Ho Chi Minh City Vietnam Virginia Tech Bradley Dept Elect & Comp Engn Wireless VT Blacksburg VA 24061 USA Kyung Hee Univ Dept Comp Sci & Engn Yongin South Korea

Device-to-device (D2D) communications over the licensed wireless spectrum has been recently proposed as a promising technology to meet the capacity crunch of next generation cellular networks. However, due to the high mobility of cellular devices, establishing and ensuring the success of D2D transmission become a major challenge. To this end, in this paper, a novel framework is proposed to enable devices to form multi-hop D2D connections in an effort to maintain sustainable communication in the presence of device mobility. To solve the problem posed by device mobility, in contrast to existing works, which mostly focus on physical domain information, a durable community-based approach is introduced taking social encounters into context. It is shown that the proposed scheme can derive an optimal solution for time sensitive content transmission while also minimizing the cost that the base station pays in order to incentivize users to participate in D2D. Simulation results show that the proposed social community aware approach yields significant performance gain, in terms of the amount of traffic offloaded from the cellular network to the D2D tier, compared with the classical social-unaware methods.

关键词： Multi-hop device-to-device communication optimization algorithm social community content delivery

来源：评论

学校读者我要写书评

暂无评论

An Efficient Approach for Filling Gaps in Landsat 7 Satellite Images

引用

IEEE GEOSCIENCE AND REMOTE SENSING LETTERS 2017年第1期14卷 62-66页

作者： El Fellah, Salma Rziza, Mohammed El Haziti, Mohamed Mohammed V Univ URAC 29 CNRST Fac SciLRIT Associated Unit Rabat Morocco

Landsat 7 Enhanced Thematic Mapper Plus (ETM+) satellite imagery presents an important data source for many applications related to remote sensing. However, the scan line corrector (SLC) failure has seriously limited the scientific applications of ETM+ data since SLC failed permanently on May 31, 2003, resulting in about 22% of the image data missing in each scene. In this letter, we propose to apply a new method to fill the missing information (gap) in the satellite image without any spatial or spectral constraint applied on the neighborhood of missing pixels. The method can also simultaneously remove various types of noise, including Gaussian noise and impulse noise, affected in the acquisition process. This proposed concept is formulated as a consecutive multilevel Otsu and Two-Threshold Binary Decomposition to detect the boundary of the damaged region (gaps) and then reconstruct the edge of the damaged region based on boundary restoration. In the final step, we applied the well-known matrix completion as a low-rank approximation problem guided by boundary reconstructed. We achieve better approximation of the rank by minimizing the truncated nuclear norm with accelerated proximal gradient line, a method for convex optimization problems. The results show the capability of our approach to predict the missing values accurately in terms of quality, time, and without the need of outside information. This letter also shows encouraging results on both synthetic and real visual data sets.

关键词： Gap filling Landsat 7 Enhanced Thematic Mapper Plus (ETM plus ) matrix completion optimization algorithm remote sensing scan line corrector (SLC)-off segmentation

来源：评论

学校读者我要写书评

暂无评论

Gauging megadiversity with optimized and standardized sampling protocols: A case for tropical forest spiders

引用

ECOLOGY AND EVOLUTION 2017年第2期7卷 494-506页

作者： Malumbres-Olarte, Jagoba Scharff, Nikolaj Pape, Thomas Coddington, Jonathan A. Cardoso, Pedro Univ Copenhagen Nat Hist Museum Denmark Ctr Macroecol Evolut & Climate Copenhagen Denmark Univ Copenhagen Nat Hist Museum Denmark Copenhagen Denmark Natl Museum Nat Hist Smithsonian Inst Washington DC 20560 USA Univ Helsinki Finnish Museum Nat Hist Helsinki Finland

Characterizing and monitoring biodiversity and assessing its drivers require accurate and comparable data on species assemblages, which, in turn, should rely on efficient and standardized field collection. Unfortunately, protocols that follow such criteria remain scarce and it is unclear whether they can be applied to megadiverse communities, whose study can be particularly challenging. Here, we develop and evaluate the first optimized and standardized sampling protocol for megadiverse communities, using tropical forest spiders as a model taxon. We designed the protocol COBRA-TF (Conservation Oriented Biodiversity Rapid Assessment for Tropical Forests) using a large dataset of semiquantitative field data from different continents. This protocol combines samples of different collecting methods to obtain as many species as possible with minimum effort (optimized) and widest applicability and comparability (standardized). We ran sampling simulations to assess the efficiency of COBRA-TF (optimized, non-site-specific) and its reliability for estimating taxonomic, phylogenetic, and functional diversity, and community structure by comparing it with (1) commonly used expert-based ad hoc protocols (nonoptimized, site-specific) and (2) optimal protocols (optimized, site-specific). We then tested the performance and feasibility of COBRA-TF in the field. COBRA-TF yielded similar results as ad hoc protocols for species (observed and estimated) and family richness, phylogenetic and functional diversity, and species abundance distribution. Optimal protocols detected more species than COBRA-TF. Data from the field test showed high sampling completeness and yielded low numbers of singletons and doubletons. Optimized and standardized protocols can be as effective in sampling and studying megadiverse communities as traditional sampling, while allowing data comparison. Although our target taxa are spiders, COBRA-TF can be modified to apply to any highly diverse taxon and habitat as lon

关键词： Araneae Arthropoda optimization algorithm rapid biodiversity assessment sampling methodology species richness Udzungwa Mountains

来源：评论

学校读者我要写书评

暂无评论

Based on rough set and fuzzy clustering of MRI brain segmentation

引用

International Journal of Biomathematics 2017年第2期10卷 187-197页

作者： Yang Zhang Shufan Ye Weifeng Ding School of Information and Engineering Wenzhou Medical University Wenzhou Zhejiang 325000 P. R. China Zhejiang Zhonglan Environment Technology Ltd. Wenzhou Zhejiang 325000 P. R. China 118 Hospital of People's Liberation Army Wenzhou Zhejiang 325000 P. R. China

A new method of MRI brain segmentation integrates fuzzy c-means （FCM） clustering and rough set theory. In this paper, we use rough set algorithm to find the suitable initial clustering number to initial clustering centers for FCM. Then we use FCM to MRI brain segmentation, but the algorithm of FCM has the limitation of converging to local infinitesimal point in medical segmentation. While avoiding being trapped in a local optimum, we use the particle swarm optimization algorithm to restrict convergence of FCM which can reduce calculation. The final experiment results show that improved algorithm not only retains the advantages of rapid convergence but also can control the local convergence and improve the global search ability. The method in this paper is better than that of cluttering performance.

关键词： FCM optimization algorithm rough set MRI segment.

来源：评论

学校读者我要写书评

暂无评论

Droplet Size-Aware and Error-Correcting Sample Preparation Using Micro-Electrode-Dot-Array Digital Microfluidic Biochips

引用

IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2017年第6期11卷 1380-1391页

作者： Li, Zipeng Lai, Kelvin Yi-Tse Chakrabarty, Krishnendu Ho, Tsung-Yi Lee, Chen-Yi Duke Univ Dept Elect & Comp Engn Durham NC 27708 USA Natl Chiao Tung Univ Dept Elect Engn Hsinchu 300 Taiwan Natl Tsing Hua Univ Dept Comp Sci Hsinchu 300 Taiwan

Sample preparation in digital microfluidics refers to the generation of droplets with target concentrations for on-chip biochemical applications. In recent years, digital microfluidic biochips (DMFBs) have been adopted as a platform for sample preparation. However, there remain two major problems associated with sample preparation on a conventional DMFB. First, only a (1: 1) mixing/splitting model can be used, leading to an increase in the number of fluidic operations required for sample preparation. Second, only a limited number of sensors can be integrated on a conventional DMFB;as a result, the latency for error detection during sample preparation is significant. To overcome these drawbacks, we adopt a next generation DMFB platform, referred to as micro-electrode-dot-array (MEDA), for sample preparation. We propose the first sample-preparation method that exploits the MEDA-specific advantages of fine-grained control of droplet sizes and real-time droplet sensing. Experimental demonstration using a fabricated MEDA biochip and simulation results highlight the effectiveness of the proposed sample-preparation method.

关键词： Digital mirofluidics micro-electrode-dot-array sample preparation optimization algorithm error recovery

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：