检索结果-内蒙古大学图书馆

Remote Sensing Applied to the Extraction of Road Geometric Features Based on Optimum Path Forest Classifiers, Northeastern Brazil

引用

Journal of Geographic Information System 2020年第1期12卷 15-44页

作者： Márcia Macedo Maria Maia Emilia Kohlman Rabbani Oswaldo Lima Neto Post-Graduate Program in Civil Engineering UFPE Pernambuco Brazil Post-Graduate Program in Civil Engineering UPE Pernambuco Brazil

One of the principal difficulties related to road safety management in Brazil is the lack of data on road projects, especially those on rural roads, which makes it difficult to use road safety studies and models from other countries as a reference. Updating road networks through the use of hyperspectral remote sensing images can be a good alternative. However, accurately recognizing and extracting hyperspectral images from roads has been recognized as a challenging task in the processing of hyperspectral data. In order to solve the aforementioned challenges, Hyperion hyperspectral images were combined with the Optimum Forest Path (OPF) algorithm for supervised classification of rural roads and the effectiveness of the OPF and SVM classifiers when applied to these areas was compared. Both classifiers produced reasonable results, however, the OPF algorithm outperformed SVM. The higher classification accuracy obtained by the OPF was mainly attributed to the ability to better distinguish between regions of exposed soil and unpaved roads.

关键词： Roads Multispectral Images Hyperspectral Images Optimum Path Forest Algorithm

来源：评论

学校读者我要写书评

暂无评论

Vibration analysis of a production platform induced by mechanical equipment

Vibration analysis of a production platform induced by mecha...

引用

10th International Conference on Computational Structures Technology, CST 2010

作者： Rimola, B.D. Da Silva, J.G.S. Sieira, A.C.C.F. De Lima, L.R.O. Da Neves, L.F.C. Civil Engineering Post-graduate Programme UERJ PGECIV State University of Rio de Janeiro Brazil Structural Engineering Department UERJ State University of Rio de Janeiro Brazil Civil Engineering Department University of Coimbra ISISE Portugal

ISBN: (纸本)9781905088386

The competitive trends of the world market have long been forcing structural engineers to develop minimum weight and labour cost solutions. A direct consequence of this new design trend is a considerable increase in problems related to unwanted floor vibrations. For this reason, the structural floors systems can become vulnerable to excessive vibrations, for example, produced by impacts such as mechanical equipments (rotating machinery). This way, the present paper investigated the dynamic behaviour of a production platform made of steel and located in Santos basin (Merluza field), São Paulo, Brazil, when subjected to impacts produced by mechanical equipments (rotating machinery). The structural model consists of two steel decks with a total area of 1915 m2 (upper deck: 445 m2 and lower deck: 1470 m2), supported by piles. A numerical analysis was made, in order to assess the dynamic impacts on the deck structure coming from the electrical generators and compressors. Based on the peak acceleration values, obtained on the structure steady-state response, it was possible to evaluate the structural model performance in terms of human comfort, maximum tolerances of the mechanical equipment and vibration serviceability limit states of the structural system. © civil-Comp Press, 2010.

关键词： Vibration analysis

来源：评论

学校读者我要写书评

暂无评论

An assessment of rolled stainless steel angles under compression 7th

An assessment of rolled stainless steel angles under compres...

引用

7th International Conference on Structural engineering, Mechanics and Computation, 2019

作者： da Sirqueira, A.S. da Vellasco, P.C.G.S. de Lima, L.R.O. da Silva, A.T. Rodrigues, M.C. Vellasco, M.M.B.R. PGECIV-Civil Engineering Post-Graduate Program UERJ – State University of Rio de Janeiro Brazil Structural Engineering Department UERJ – State University of Rio de Janeiro Brazil Electrical Engineering Department PUC-Rio – Pontifical Catholic University of Rio de Janeiro Brazil

ISBN: (纸本)9781138386969

Stainless steel has been used in several types of constructions. Although many of their mechanical properties are similar to the properties of carbon steel, their nonlinear characteristics imply in different design rules. This non-linearity mainly affects the response to local and flexural buckling. The Eurocode 3: Part 1-4 (2006) stainless steel design standard can be applied to hot rolled, welded and cold formed products, but the provisions of this code are rather conservative, with a limited application due to the lack of experimental data. Thus, one of those areas that require attention and study concerns the behaviour of columns made of rolled stainless steel angles. This paper describes an experimental campaign made on rolled stainless steel angles under axial compression. The tests were performed on stainless steel rolled angles with lengths varying from 150 mm to 1400 mm while the collapse involved: flexural-torsional and flexural buckling modes. © 2019 Taylor & Francis Group, London, UK.

关键词： Hot rolling

来源：评论

学校读者我要写书评

暂无评论

Effect of Method and Duration of Curing on the Compressive Strength of the Lime-Fly Ash Geopolymer Concrete 1

Effect of Method and Duration of Curing on the Compressive S...

引用

1st Progress in Science and Technology Research Symposium, PSTRS 2019

作者： Adam, Andi Arham Akifa, Sri Nur Siregar, Atur P.N. Mustofa Department of Civil Engineering Tadulako University Indonesia Post-Graduate Program Tadulako University Indonesia Department of Mechanical Engineering Tadulako University Indonesia

The use of lime to produce ambient cured Geopolymer concrete is one of a practical solution to avoid heat curing in the production of geopolymer concrete. The addition of lime in the geopolymer system will add another hardened mechanism, i.e. hydration in addition to condensation-polymerisation. This research aims to determine the influence of air and water curing on the strength of geopolymer concrete which uses class F fly ash and lime as raw materials. The geopolymer concrete was produced by varying the activator (sodium silicate and sodium hydroxide) with the variation of the activator to binder ratio of 0.45, 0.50, 0.55, and 0.60. Five per cent of the fly ash was replaced by slaked lime and the water added to the mix to maintain the ratio of water to solid (activator + binder) to 0.32. The test specimens were 100 mm dia x 200 mm height cylinder. Water-immersion curing was performed for 7, 14, and 21 days and the compressive strength test was done at 28 days. The results show that there is a difference in the curing process between the geopolymer concrete and the normal concrete. In the geopolymer concrete, there is a decrease in compressive strength if soaked for seven days and recovered with the increase in the age of immersion. Whereas for normal concrete, the compressive strength continues to increase with increasing age of immersion. © Published under licence by IOP Publishing Ltd.

关键词： Compressive strength

来源：评论

学校读者我要写书评

暂无评论

Relative importance of pathologies in the severity of facade degradation

引用

Journal of Building Pathology and Rehabilitation 2020年第1期5卷 1-10页

作者： Bauer, Elton Piazzarollo, Carla Bozzi de Souza, Jéssica Siqueira dos Santos, Danilo Gonçalves Post-Graduate Program in Structures and Civil Construction Civil and Environmental Engineering Department University of Brasília Campus Universitário Darcy Ribeiro Asa Norte Brasília DF Brazil

The facade is the main protective barrier against the atmospheric agents acting in a building. Many times, as a result of these agents, the facade manifests pathologies that lead to the loss of performance of the external wall claddings. This article aims to establish and score the importance of the pathologies involved in the cement mortars rendering. The probable causes and the influence on the performance decrease over time are analyzed. The methodology is based on the survey and mapping of the pathologies observed in field survey, correlating these pathologies with probable causes and implications for the system performance. Among the active pathologies, cracks had both a higher intensity of occurrence and a greater gravity compared to the others. Some pathologies, such as detachment and efflorescence, although of great importance in the degradation, are little observed in the studied buildings. As a result, is presented a scale of importance of pathologies, which has great application for the development of facade degradation models. © 2020, Springer Nature Switzerland AG.

关键词： Cement mortar Degradation External wall claddings Facades Pathologies

来源：评论

学校读者我要写书评

暂无评论

Computational modelling of the static and dynamic behaviour of wind turbine tower structures

Computational modelling of the static and dynamic behaviour ...

引用

9th International Conference on Computational Structures Technology, CST 2008

作者： Da S. Sirqueira, A. Da S. Vellasco, P.C.G. Da Silva, J.G.S. De Lima, L.R.O. De Andrade, S.A.L. Post-graduate Programme in Civil Engineering - PGECIV State University of Rio de Janeiro - UERJ Brazil Structural Engineering Department State University of Rio de Janeiro - UERJ Brazil Mechanical Engineering Department State University of Rio de Janeiro - UERJ Brazil

ISBN: (纸本)9781905088232

Wind farms, widely used in Europe, still do not represent a significant parcel of the renewable energy sources utilized in Brazil. Many reasons can be attributed for this trend but the wind farm implementation costs are one of the most significant factors. An optimization of the wind turbine supporting tower structure, that roughly represents 20% of the global costs, will definitively contribute for the implementation of new and cost-effective wind farms plants. A 10% economy is not unusual with an optimization process of the steel tower structural elements. On the other hand, these aims can only be achieved with a complete understanding of the wind towers static and dynamic behaviour. A finite element computational model was developed and implemented in the ANSYS program, based on a typical wind turbine supporting steel tower structure. This paper is centred on the geometric and material non-linear finite element analysis to investigate the ultimate and serviceability limit states that control the wind turbine supporting tower structural response. The study also presented an evaluation of the dynamical response of these structures focused on a modal analysis. The model calibration was made by comparisons to experimental data, acquired in a full scale wind tower structure, proving to be able to fully represent its structural dynamic performance. © civil-Comp Press, 2008.

关键词： Structural dynamics

来源：评论

学校读者我要写书评

暂无评论

GIS-Based Methodology for Crash Prediction on Single-Lane Rural Highways

引用

Journal of Geographic Information System 2021年第2期13卷 98-121页

作者： Márcia Macedo Emilia Kohlman Rabbani Maria Maia Marlos Macedo Bianca Ferreira Post-Graduate Program in Civil Engineering UPE Recife Brazil Post-Graduate Program in Systems Engineering UPE Recife Brazil Graduate Program in Architecture and Urban Planning UNICAP Recife Brazil

Due to the need to update the current guidelines for highway design to focus on safety, this study sought to build an accident prediction model using a Geographic Information System (GIS) for single-lane rural highways, with a minimum of statistically significant variables, adequate to the Brazilian reality, and improve accident prediction for places with similar characteristics. A database was created to associate the accident records with the geometric parameters of the highway and to fill in the gaps left by the absence of geometric highway plans through geometric reconstitution or semi-automatic extraction of highways using satellite images. The Generalized Estimating Equation (GEE) method was applied to estimate the coefficients of the model, assuming negative distribution of the binomial error for the count of observed accidents. The accident frequency and annual average daily traffic (AADT) were analyzed, along with the spatial and geometric characteristics of 215 km of federal single-lane rural highways between 2007 and 2016. The GEE procedure was applied to two models having three variations of distinct homogeneous segmentation, two based on segments and one based on the kernel density estimator. To assess the effect of constant traffic, two more variations of the models using AADT as an offset variable were considered. The predominant correlation structure in the models was the exchangeable. The principal contributing factors for the occurrence of collisions were the radius of the horizontal curve, the grade, segment length, and the AADT. The study produced clear indicators for the design parameters of roadways that influence the safety performance of rural highways.

关键词： Roads GEE Single-Lane Rural Highways GIS Crash Prediction

来源：评论

学校读者我要写书评

暂无评论

The Effect of EPS Addition to Soil Stabilized with Fly Ash as Lightweight Fill Materials for Embankment Construction 1

The Effect of EPS Addition to Soil Stabilized with Fly Ash a...

引用

2018 1st Workshop on engineering, Education, Applied Sciences, and Technology, WEAST 2018

作者： Syahril Somantri, Andri Krisnandi Febriansya, Aditia Civil Engineering Department Politeknik Negeri Bandung Bandung Indonesia Post-Graduate Stud. of Infrastructure Engineering Study Program Applied Master Program Politeknik Negeri Bandung Bandung Indonesia

Design and construction of road embankment presents several challenges, including the possibility of bearing capacity failure, large total settlement, differential settlement, and slope instability, which may result from the weight of the embankment construction itself, and/or weak foundation. A number of techniques have been developed and can be used to overcome these problems, one of them is by modifying the weight of the embankment itself with the use of lightweight materials, such as soil-EPS mixture. The use of soil-EPS mixture as lightweight material provides several advantages, among which can achieve the same volume or elevation requirement with a significantly lighter weight compared to ordinary materials, improving slope stability, embankment over high compressibility soil, and to reduce soil pressure to soil retaining structures, abutment or bridge pillar. Fly ash also added to act as binder to increase shear strength of mixture. The result of the compaction test shows that the addition of a small amount of EPS to the mixture can significantly reduce the maximum dry density of the mixture. Triaxial UU and UCS test results show a reduction in mixture strength as EPS contents increase, but due to the presence of fly ash increases the strength of mixture as the number of day increases, so that the use of lightweight materials has the potential to be one of soil improvement solutions. © Published under licence by IOP Publishing Ltd.

关键词： Mixtures

来源：评论

学校读者我要写书评

暂无评论

Dynamic Analysis of Steel-Concrete Composite Building Floors Subjected to Human Rhythmic Activities

引用

ce/papers 2017年第2-3期1卷 4000-4009页

作者： Campista, Fernanda Fernandes da Silva, José Guilherme Santos Civil Engineering Post-graduate Programme PGECIV State University of Rio de Janeiro UERJ Brazil

This work aims is to investigate the structural dynamic response of steel-concrete composite floors, when subjected to rhythmic human activities, based on experimental tests and numerical modelling, from the point of view of human comfort. The main focus of this paper is to study the effect of the dynamic interaction between the occupants and the floors, representing these people by SDOF biodynamic models (mass-spring-damper systems), in order to better evaluate the dynamic response and the vibration serviceability states. This way, the investigated structural model is related to a steel-concrete composite building which is composed of three floors used for aerobics classes, with dimensions of 20m × 20m, a total area of 1200m2 (3 × 400m2) and a ceiling height of 4m. The numerical modelling of the structure was performed by ANSYS program and was based on the finite element method (FEM). In order to evaluate the dynamic response of the investigated steel-concrete composite building, accelerations associated with 32 individuals practicing rhythmic activities were experimentally obtained to introduce them into the finite element model. Thus, the dynamic response of the building floors was evaluated in terms of the peak accelerations, RMS and VDV values, according to human comfort criteria and considering situations of the design practice. © 2017 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

关键词： Floors

来源：评论

学校读者我要写书评

暂无评论

Vibration Analysis and Human Comfort Investigation of a Steel-Concrete Composite Building under Nondeterministic Wind Loadings

引用

ce/papers 2017年第2-3期1卷 4010-4019页

作者： da Silva, José Guilherme Santos Barboza, Rafael Rangel Civil Engineering Post-graduate Programme PGECIV State University of Rio de Janeiro UERJ Brazil

Based on a favourable economic scenario combined with a significative technological advance in science materials and also construction processes, it must be emphasized that the Brazilian cities have shown substantial growth, regarding the construction of tall and slender buildings. This architectural trend has conducted the design of these buildings to solutions composed by very flexible structural systems, resulting in slender buildings with very low natural frequencies values and therefore more susceptible to problems of excessive vibrations, undesirable crack openings and even discomfort to the occupants. This way, having in mind the slenderness levels presented more recently, these buildings need to have their structural dynamic behaviour investigated, in order to ensure the human comfort. Thus, this research work aims to investigate the dynamic structural behaviour and also evaluates the human comfort of tall buildings, when subjected to the non-deterministic action of the wind. This way, the structural behaviour of a forty eight-storey steel-concrete composite building with 172.8m high subjected to the nondeterministic wind dynamic actions is investigated. The results obtained along the numerical analysis, in terms of the displacements and accelerations values, in time and frequency domain, are compared with the limits proposed by technical guides and design recommendations, aiming to evaluate the human comfort levels of the analysed building, regarding to the situations of the design practice. © 2017 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

关键词： Structural dynamics

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：