Estimating residual value of heavy construction equipment using ensemble learning

Knowing the right moment for the sale of used heavy construction equipment is important information for every construction company. The proposed methodology uses ensemble machine learning techniques to estimate the price (residual value) of used heavy equipment in both the present and the near future. Each machine in the model is represented with four groups of attributes: age and mechanical (describing the machine) and geographical and economic (describing the target market). The research suggests that the ensemble model based on random forest, light gradient boosting, and neural network members, as well as support vector regression as a decision unit, gives better estimates than the traditional regression or individual machine learning models. The model is built and verified on a large data set of 500,000 machines advertised in 50 US states from 1989 to 2012

Complication of pregnancy as sequence of hypoxemia of uteroplacental unit

The pregnancy physiologically navigates, sort of speaking, the hematopoietic system in the direction of hypercoagulabile state, which grows stronger throughout the pregnancy and reaches its maximum at the time of the delivery. These changes are considered to be the protection of the pregnant woman during puerperium, but if over-emphasized, they could lead to complications in both mother and the fetus. The main hypothesis of pathophysiology of these problems, during pregnancy, is based on the events of forming the blood vessels between the placenta and the uterus. During the forming of placental circulation, as a result of non-adequate placentation and placental vascular thrombosis, certain secondary reactions may be manifested, such as: placental abruption, hypoxia and hypoxemia of the fetus, which result as fetal growth restriction. These states may be consequences of congenital or acquired thrombophilia. The therapy advised to these women varies, but there are no absolute evidences that it is obligatory. Clinical experience suggests that the use of aspirin, in the state of antiphospholipid syndrome, leads to better results, considering both the mother and the fetus

Models related to the moving load problems

In this paper different mathematical models of the vehicle load are presented, depending on the one of the moving load types. In general, vehicle load models can be classified into two types: static and dynamic moving load models. Static moving load model is model with nonvarying load value and shape in time. Dynamic moving load model is defined by differential equations of motion where the road roughness function affects the solution. Due to this influence some of the differential equations cannot be solved analytically and the numerical approach has to be performed. Therefore, in this work Matlab Simulink models have been developed to solve this problem. Validation of Simulink models is carried out and presented for all analysed dynamic moving load models

Analiza vezane energije i emisije CO2 za izvođenje mostovske konstrukcije sa stanovišta održivosti

This paper presents a comparative analysis of embodied energy and CO2 emission, in the construction process of three bridge structures. Analyzed structures are prestressed concrete bridges with different structural systems and a total length of 88 meters. The correlation of structural system, construction method, material quantities and embodied energy and CO2 emission were considered. Influence of the selected solutions in main steps of design and construction on the energy consumption and the emission of CO2 is presented. The results should provide a better understanding of the effects of certain factors, in the bridge construction process, and their impact on the environment.U radu je prikazana uporedna analiza vezane energije i emisije CO2 u procesu gradnje, za tri mostovske konstrukcije. Analizirane konstrukcije su prethodno napregnuti betonski mostovi, različitih statičkih sistema, ukupne dužine 88 metara. Razmatrana je međusobna uslovljenost izbora konstruktivnih rešenja, načina izvođenja konstrukcije, količine utrošenog materijala, vezane energije i emisije CO2. Dat je uvid u način na koji se glavni koraci u projektovanju i izvođenju mostova odražavaju na energetski utrošak i emisiju CO2, procentualno i u ukupnom iznosu. Dobijeni rezultati bi trebalo da omoguće bolje sagledavanje uticaja pojedinih faktora u procesu izvođenja mostova i njihov uticaj na životnu sredinu

Comparative seismic analysis of RC buildings under influence of soil-structure interaction

In this paper the effects of soil-structure interaction (SSI) on reinforced concrete (RC) buildings are analyzed. The dynamic analysis was carried out for two buildings of different heights, founded on three different types of soils, and two different types of foundation, with and without soil interaction. Ten earthquake records, chosen for Belgrade site, were used in the response spectrum analysis. The mean spectrum at the base of the soil deposit and the mean spectra at the surface of each soil types were derived. Calculation was performed using the originally coded MATLAB program, which accounts for downward and upward wave propagation. The influence of the soil layer over the bedrock on the response of the RC buildings was calculated using the commercial software SAP2000. The conclusions were carried out according to theobtained results

Analysis of the embodied energy and the CO2 emission in construction process of a bridge structure from the aspect of sustainability

This paper presents a comparative analysis of embodied energy and CO2 emission, in the construction process of three bridge structures. Analyzed structures are prestressed concrete bridges with different structural systems and a total length of 88 meters. The correlation of structural system, construction method, material quantities and embodied energy and CO2 emission were considered. Influence of the selected solutions in main steps of design and construction on the energy consumption and the emission of CO2 is presented. The results should provide a better understanding of the effects of certain factors, in the bridge construction process, and their impact on the environment.U radu je prikazana uporedna analiza vezane energije i emisije CO2 u procesu gradnje, za tri mostovske konstrukcije. Analizirane konstrukcije su prethodno napregnuti betonski mostovi, različitih statičkih sistema, ukupne dužine 88 metara. Razmatrana je međusobna uslovljenost izbora konstruktivnih rešenja, načina izvođenja konstrukcije, količine utrošenog materijala, vezane energije i emisije CO2. Dat je uvid u način na koji se glavni koraci u projektovanju i izvođenju mostova odražavaju na energetski utrošak i emisiju CO2, procentualno i u ukupnom iznosu. Dobijeni rezultati bi trebalo da omoguće bolje sagledavanje uticaja pojedinih faktora u procesu izvođenja mostova i njihov uticaj na životnu sredinu

Free Vibration of Plate Assemblies Using Spectral Element Method

In this paper, the Spectral Element Method (SEM) is applied to analyze free vibration of two plates perpendicularly assemblied, so-called L plate. In order to obtain necessary results, the transformation matrices have been developed for two positions of rectangular plates. Numerical example is conducted for L plate assemblies consisting of rectangular plates with same mechanical and geometrical properties. The accuracy of the results obtained by the SEM is verified by comparing them with the solutions obtained by conventional Finite Element Method (FEM)

Models related to the moving load problems

In this paper different mathematical models of the vehicle load are presented, depending on the one of the moving load types. In general, vehicle load models can be classified into two types: static and dynamic moving load models. Static moving load model is model with nonvarying load value and shape in time. Dynamic moving load model is defined by differential equations of motion where the road roughness function affects the solution. Due to this influence some of the differential equations cannot be solved analytically and the numerical approach has to be performed. Therefore, in this work Matlab Simulink models have been developed to solve this problem. Validation of Simulink models is carried out and presented for all analysed dynamic moving load models

Dinamički odgovor podloge duž trase buduće linije beogradskog metroa

Zbornik radova Građevinskog fakultet

Development of sustainable cities: effect of traffic induced vibrations on buildings and humans

U ovom radu dat je kratak prikaz nekih od najznačajnijih rezultata učesnika projekta TR36046: „Istraživanje dejstva vibracija na ljude i objekte u cilju održivog razvoja gradova“, Ministarstva prosvete, nauke i tehnološkog razvoja Republike Srbije. Opisan je način nastanka i prostiranja vibracija, kao i način procene dejstva vibracija na objekte i ljude sa osvrtom na nemačke i britanske standarde. Predstavljeni su empirijski i numerički modeli za analizu vibracija od saobraćaja na osnovu izvršenih merenja.This paper presents some of the most important results of the project TR36046: “Investigation of vibration effects on humans and buildings in the aim of the sustainable development of cities” financed by the Ministry of Education, Science and Technological Development of the Republic of Serbia. The paper describes the vibrations generation and propagation as well as the estimation of the effects of vibrations on objects and people with a reference to German and British standards. Empirical and numerical models for the traffic induced vibrations analysis based on the performed measurements were presented