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

Interfacial Polarization and Dielectric Properties of Epoxy/Graphite Flakes Composites

Dielectric properties of composites based on bisphenol-A-epoxy resin loaded with various content of graphite flakes (GF) have been studied. The dielectric permeability, tangent loss and ac conductivity have been examined in wide temperature (170 – 370 K) and frequency (20 Hz – 200 kHz) range. In composites loaded with GF flakes up to 10 wt.%, the dominant conduction mechanism is tunneling of electrons, while loading of 15 wt.% gives rise to electron conduction through direct contacts between fillers. Dielectric properties of composites are largely determined by the nature of the filler/matrix interface, the filler surface area and the inherent conductivity of the fillers. At low electric field frequencies, dominates socalled interfacial (or space charge) polarization due to accumulation of free charges at the interfaces between two phases (filler and matrix), which differ in electrical conductivity.Influence of the filler surface chemistry have been studied for composites loaded with 5 wt.% graphite flakes obtained: (i) under wet milling, without (GF) or with (GF-Tr100x) adding Triton-100x as a surfactant, or (ii) under dry milling in the presence of KOH (GF-KOH). The surface treatment with KOH notable increased dielectric constant of the epoxy/GF-KOH5 composite, keeping low tangent loss, comparable to the counterpart, the epoxy/GF5 composite

Genetski algoritmi za rasporedivanje rukovatelja gradevinskih strojeva

The authors describe the methodology for using genetic algorithms in solving problems of optimum assignment of tasks to construction machinery operators, aimed at achieving maximum efficiency. A special emphasis is placed on the influence of human factor (operator competence) on the efficiency of the system. The methodology for creating a genetic algorithm is described, and its use in practical problem solving is presented. The achieved results, and their sensitivity to the number of variables, is discussed

Genetski algoritmi za rasporedivanje rukovatelja gradevinskih strojeva

The authors describe the methodology for using genetic algorithms in solving problems of optimum assignment of tasks to construction machinery operators, aimed at achieving maximum efficiency. A special emphasis is placed on the influence of human factor (operator competence) on the efficiency of the system. The methodology for creating a genetic algorithm is described, and its use in practical problem solving is presented. The achieved results, and their sensitivity to the number of variables, is discussed

ARCHITECTURE AND CERAMIC MATERIALS, DEVELOPMENT THROUGH TIME: CERAMIC TILES AND CERAMIC ROOF TILES

Ceramic tiles and roof covers have been used in construction of architectonic structures from the earliest times. Their relatively simple production, as well as acceptable cost, contributed to the mass usage of these products.The paper presents a review of ceramic tiles and roof tiles, by laying out their development, shapes, physical properties and usage through history in various climates and time periods.The aim of the paper is understanding the importance of use and development of these products in architecture. 

ARCHITECTURE AND CERAMIC MATERIALS, DEVELOPMENT THROUGH TIME: ADOBE AND BRICK

The fired earth products are from the dawn of time very readily used as a building material in architecture. Regardless of the geographical area, or era, both adobe and bricks have been often used because they are easy and cheap to manufacture.The paper provides the review of adobe and brick use, from the earliest times until nowadays. The evolution of their production, forms, physical properties and ways of their usage on the structures are presented.The goal of the paper is an analysis of development of use of these products which will certainly remain in use for many years to come.

Characterization of Roman mortar from the Mediana archeological site

Ovaj rad prikazuje istraživanje rimske žbuke rabljene za konstrukciju poda u objektima koji su imali sustav podnog grijanja – hipokaust, u rezidencijalnim vilama s peristelom (Naisus, Srbija). Ispitano je i analizirano ukupno sedam uzoraka žbuke s različitih lokacija vile s ciljem dobivanja informacija o njezinim morfološkim, mineraloškim, kemijskim i osnovnim fizikalnim karakteristikama. Za utvrđivanje ovih svojstava rabljena je: optička mikroskopija, skenirajući elektronski mikroskop (SEM), s EDS analizom, difrakcijska analiza s X-zrakama (XRD). Žbuka ima prilično ujednačene karakteristike preko cijele površine poda hipokausta. Žbuka dominantno čini karbonatno vezivo i agregat veličine zrna od 0,05 do 2 mm s rijetkom pojavom zrna dimenzija 10 mm. Kao agregat za žbuku rabljeni su dijelovi žbuke, zrna krečnjaka, kvarc, metamorfiti i vulkaniti. Uporaba drobljene opeke i prisustvo reakcijskog ruba, potvrđuje njezinu funkciju hidrauličnog vezivanja. Slaba veza između zrna agregata i krečnjačkog veziva omogućava transport vode kroz formiranu tranzitnu zonu.This paper presents the study of the Roman mortar used for construction of floors in the buildings which possessed floor heating system – hypocaust, in the residential villa with the peristyle (Naisus, Serbia). A total of seven samples of mortar from different locations of the villa were examined and analyzed for information about its morphological, mineralogical, chemical and basic physical properties. In order to determine these properties were used: optical microscopy, the scanning electron microscopy (SEM) with EDS analysis, X-ray diffraction analysis (XRD). The mortar is dominantly made of carbonate binder and the aggregate of grain size 0,05 to 2 mm with a rare occurrence of 10 mm grains. Fragments of mortar, grains of limestone, quartz, metarmorphite and vulcanite were used for the mortar aggregate. Usage of crushed brick and reaction rim confirms its function of hydraulic binder. The weak bonds between the aggregate grains and limestone binder facilitate transport of water through the formed transit zones

Molekularna karakterizacija mikroorganizama izolovanih iz kontaminirane životne sredine i njihova primena za degradaciju bis(2-hidroksietil) tereftalata

Plastika kao izvor zagađenja postaje sve veći globalni problem. Većina plastike je dizajnirana za jednokratnu upotrebu, što dodatno povećava količinu plastičnog otpada. Usled preopterećenja zemlje i voda plastičnim otpadom neophodno je razviti procese koji će omogućiti efikasno uklanjanje plastike iz životne sredine [1]. Polietilen-tereftalat (PET) spada u najkorišćenije polimere za izradu plastike, te je neophodno naći efikasan način za njegovu degradaciju. Kao povoljan metod degradacije PET plastike predlaže se enzimska hidroliza korišćenjem mikroorganizama koji kao izvor ugljenika mogu koristiti PET [2]. Bis-(2-hidroksietil)-tereftalat (BHET) je intermedijer u izgradnji PET polimera, te je korišćen kao model sistem za ispitivanje degradacije PET plastike [3]. Cilj ovog rada je bila identifikacija mikroorganizama koji potencijalno razgrađuju BHET, kao i primena čistih kultura za degradaciju istog. Tokom studije testirana je osetljivost mikroorganizama na antibiotike (penicillin i nalidiksinsku kiselinu). Praćena je pojava zona inhibicije 24h nakon zasejavanja mikroorganizama. Nakon antibiograma rađeno je izolovanje DNK po protokolu za Grampozitivne i Gram-negativne bakterije. Za svaki soj mikroorganizama umnoženi su geni za 16s rRNK lančanom reakcijom polimeraze (PCR). Rađena je preparativna agarozna elektroforeza sa PCR produktima i DNK je ekstrahovana iz gela. Uzorci su poslati na sekvenciranje i dobijene sekvence su spojene u programu BioEdit. Dobijene sekvence su poređene u NCBI BLAST bazi podataka i identifikovani su rodovi izolovanih mikroorganizama. Ispitivana je degradacija BHET-a pomoću čistih kultura mikroorganizama, gde je korišćena mineralna podloga, a jedan od izvora ugljenika bio je BHET. Inkubacija je trajala 14 dana, a degradacija je praćena u prvom i poslednjem danu inkubacije pomoću tankoslojne hromatografije (TLC). Korišćen je sistem rastvarača benzen:dioksan:sirćetna kiselina (90:25:4, v/v/v). Na slici 1 su prikazani rezultati TLC-a gde su korišćeni sojevi Pseudomonas, Bacillus i Rhodococcus. Kao najefikasniji soj pokazao se Rhodococcus. Kako je pokazano da sami mikroorganizmi mogu da potpuno ili delimično transformišu BHET, dalji eksperimenti će se odvijati u smeru ispitivanja potpune degradacije pomoću konzorcijuma mikroorganizama.KNJIGA IZVODA: 9. simpozijum Hemija i zaštita životne sredine Kladovo, 4-7. jun 2023. BOOK OF ABSTRACTS : 9th Symposium Chemistry and Environmental Protection Kladovo, 4-7th June 202

Characterization of Roman mortar from the Mediana archeological site

Ovaj rad prikazuje istraživanje rimske žbuke rabljene za konstrukciju poda u objektima koji su imali sustav podnog grijanja – hipokaust, u rezidencijalnim vilama s peristelom (Naisus, Srbija). Ispitano je i analizirano ukupno sedam uzoraka žbuke s različitih lokacija vile s ciljem dobivanja informacija o njezinim morfološkim, mineraloškim, kemijskim i osnovnim fizikalnim karakteristikama. Za utvrđivanje ovih svojstava rabljena je: optička mikroskopija, skenirajući elektronski mikroskop (SEM), s EDS analizom, difrakcijska analiza s X-zrakama (XRD). Žbuka ima prilično ujednačene karakteristike preko cijele površine poda hipokausta. Žbuka dominantno čini karbonatno vezivo i agregat veličine zrna od 0,05 do 2 mm s rijetkom pojavom zrna dimenzija 10 mm. Kao agregat za žbuku rabljeni su dijelovi žbuke, zrna krečnjaka, kvarc, metamorfiti i vulkaniti. Uporaba drobljene opeke i prisustvo reakcijskog ruba, potvrđuje njezinu funkciju hidrauličnog vezivanja. Slaba veza između zrna agregata i krečnjačkog veziva omogućava transport vode kroz formiranu tranzitnu zonu.This paper presents the study of the Roman mortar used for construction of floors in the buildings which possessed floor heating system – hypocaust, in the residential villa with the peristyle (Naisus, Serbia). A total of seven samples of mortar from different locations of the villa were examined and analyzed for information about its morphological, mineralogical, chemical and basic physical properties. In order to determine these properties were used: optical microscopy, the scanning electron microscopy (SEM) with EDS analysis, X-ray diffraction analysis (XRD). The mortar is dominantly made of carbonate binder and the aggregate of grain size 0,05 to 2 mm with a rare occurrence of 10 mm grains. Fragments of mortar, grains of limestone, quartz, metarmorphite and vulcanite were used for the mortar aggregate. Usage of crushed brick and reaction rim confirms its function of hydraulic binder. The weak bonds between the aggregate grains and limestone binder facilitate transport of water through the formed transit zones

Supporting information for: Water-Tuned Tautomer-Selective Tandem Synthesis of the 5,6-Dihydropyrimidin-4(3 H )-ones, Driven under the Umbrella of Sustainable Chemistry

The selective synthesis of 5,6-dihydropyrimidin-4(3H)-one scaffold (precursor of dihydrouracil) was a very difficult synthetic challenge that, so far, has not been achieved. For the first time, in this paper, green, selective and high-yields approach to 40 novel 5,6-dihydropyrimidin-4(3H)-ones (DHPMs) by one-pot reaction of aldehydes, Meldrum's acid and isothioureas under solvent-free conditions, in the presence of water, since an additive is presented. In the majority of cases, introduced methodology gave an unprecedented tautomer-selective fashion toward targeted compounds with excellent tautomeric purity (>99.9%), which reached 100% in few cases. The molecular structure of the five compounds has been determined by X-ray crystallography. In each one of them, very short length for the corresponding N2-C1 bond was noticed, making them especially interesting from a structural standpoint. This experimental fact can imply a highly localized electron π density in this part of each heterocyclic ring. The obtained experimental results, which are determined from NMR and ESI-MS study, indicate that this Biginelli-type reaction smoothly proceeds in a one-pot mode, pointing to the three-step tandem process, proceeding via the Knoevenagel, aza-Michael, and retro-Diels-Alder reactions. The presented strategy also had the following advantages: reduction amount of waste, excellent values of green chemistry metrics (cEF, EcoScale and GCIS), and it is the first eco-friendly strategy toward the DHPMs scaffold. © Copyright 2018 American Chemical Society.Supplementary data for the article: [https://dx.doi.org/10.1021/acssuschemeng.8b03127]Related to: [http://vinar.vin.bg.ac.rs/handle/123456789/7886