Comprehensive investigation of butyl stearate as a multifunctional smart concrete additive for energy‐efficient buildings

Using of phase change materials (PCM) for increasing energy savings in sustainable buildings is receiving a lot of interest in commercial applications. Butyl stearate (BS), as PCM, can be used to maintain ambient temperature in the human comfort zone and prevent temperature fluctuations by enhancing the thermal properties of concrete. The long‐term effects of BS on concrete are not well known. In this study, the applicability of BS, as a smart concrete additive, by direct incorporation in the concrete structure was investigated comprehensively including thermal, rheological, and corrosion behaviour. The thermal characterization of PCM was achieved using DSC, TGA, thermal conductivity, and thermal buffering experiments. Thermal storage capacity of BS was measured to be 134.2 J/g, which is high enough to be used for passive solar energy storage in buildings. The fresh concrete experiments revealed that workability and flowability of fresh concrete mixes were improved. The maximum hydration temperature was reduced, and a retarding effect was observed by the addition of BS. Moreover, the corrosion behaviour of steel embedded in concrete with BS as PCM was studied in a solution of NaCl (3.5 wt%) representing an aggressive environment by utilizing electrochemical impedance spectroscopy (EIS) for long‐term corrosion tests that lasted for 1 year. The open circuit potential of steel in concrete with BS showed noble potential indicating low corrosion probability. The FESEM images and polarization resistance (R_p) values showed that the addition of BS in concrete decreases corrosion of the rebar in comparison with concrete without BS. Addition of BS not only enhances thermal capacity but also exhibits corrosion protection of rebar by hindering penetration of chloride ions into the concrete.     

Production of a microfiltration membrane from acrylic fiber (AF) and low-density polyethylene (LDPE) shrink film wastes

Clean Technologies and Environmental Policy - The main purpose of this study is the production of a nanofiber membrane from industrial wastes by using the electrospinning technique and...     

Comparing of the Magnetic Force Parameters of Superconducting Maglev System Using Horizontal and Vertical PMG Geometry in Multi-Surface HTS-PMG Arrangement

Journal of Superconductivity and Novel Magnetism - In this study, a detailed static and dynamic experimental studies were carried out in different cooling heights (CH) by using two different...     

Guest editorial: New trends in data pre-processing methods for signal and image classification

Neural Computing and Applications -     

Fracture Toughness of Friction Stir-Welded Lap Joints of Aluminum Alloys

The aim of this study is to determine the fracture toughness of friction stir-welded (FSW) lap joints of aluminum alloys. FSW lap joints of AA 2014 and AA 6063 aluminum alloy plates were performed on a conventional semiautomatic milling machine. FSW lap joints were produced on alloy plates. Fracture toughness of FSW lap joints were calculated from the results of tensile shearing tests. New empirical equations were developed for fracture toughness and energy release rate based on the relation between the hardness and fracture toughness values. Fracture toughness of FSW lap joints increases exponentially as the hardness reduces. The results of the experiments showed that the amount of Si content in Al alloys affects the fracture toughness of the FSW lap joints.     

Effect of R600a on tribological behavior of sintered steel under starved lubrication

This paper describes the impact of the isobutane refrigerant on the wear performance of tribopairs at hermetic compressor bearings. The tribological behavior of 100Cr6 steel pin is investigated under starved lubrication condition in air and R600a environments when running against sintered steel which was treated with and without steam. EDS and SEM are carried out on pin and plate samples after wear tests. The results indicate that wear durability is lower for the tests with R600a than those with air. The adverse effect of R600a on wear rate is linked to the change in the viscosity and foaming characteristics of the oil in the presence of R600a as well as the lack of oxides.     

Dependence of the Structural, Electrical and Magnetic Properties of YBa2Cu3O7?δ Bulk Superconductor on the Ag Doping

The effects of Ag dopants on the superconducting properties of YBCO bulk samples, prepared under solid-state reaction method, have been studied by resistivity?Ctemperature (???CT), X-ray diffraction (XRD), scanning electron microscope (SEM), bulk density, AC susceptibility, DC magnetization measurements, and theoretical analysis. Small Ag substitutions (x??0.10) do not effect T _c of pure YBa₂Cu_3?x Ag _x O_7??? , while we observed small decreases of 1.5?K for larger doping levels (x??0.15). AC susceptibility measurements for sintered YBCO pellets have been performed as a function of temperatures at constant frequency and AC field amplitude in the absence of DC bias field. The critical current densities (J _c ) have been estimated as a function of magnetic field from the magnetization data employing Bean??s critical state model. The increase in Ag amount (x) in YBa₂Cu_3?x Ag _x O_7??? (x??0.10) system effectively decreases the intragrain critical current density, which is attributed to the reduced connectivity between the grain boundaries. In the case of small additions (x=0.05), Ag atoms fill partly the pores, leading better crystallization of the grains.     

Integration of risk matrix and event tree analysis: a natural stone plant case

Machining has considerably increased with evolving technology and increasing demand in natural stone production facilities. Different types of accidents may occur in natural stone facilities during movement, dimensioning, cutting of blocks and surface processing. These accidents may be due to physical, chemical, ergonomic and mechanical conditions. Therefore, possible work accidents and occupational diseases should be investigated. In this study, an L-matrix analysis is conducted to analyze hazards and forecast risks in natural stone facilities. According to the L-matrix results, three major initiating events are identified. For each of these initiating events, event tree analysis is used to calculate risk scores. These initiating events are hoist rope fatigue and breaking, diamond wire fatigue and breaking, and electrical leakage due to old systems. These events and their results are classified according to the probabilities using event tree analysis.     

Distributed REM-Assisted Radio Resource Management in LTE-A Networks

The successful actions of public-safety personnel during disaster recovery depend heavily on rapidly deployable and reliable mission-critical communication networks. As part of the Aerial Base Stations with Opportunistic Links for Unexpected Temporary Events project we focused on designing, prototyping and demonstrating a high-capacity, IP, mobile-data network with a low latency and large coverage, suitable for many forms of multi-media delivery, including public-safety and temporary-event use cases. In this paper we focus on a rapidly deployable wireless network based on the LTE-A-enabled, low-altitude Platforms and portable land mobile units to support disaster-relief activities. In order to minimize the inter- and intra-network interference during the radio networks operating phase, we have proposed and evaluated a novel, central-based, dynamic radio resource management algorithm for downlink communications that applies radio-interference maps from the radio environment map and traffic demands at a particular eNB. Using this we are able to efficiently allocate radio resources based on quality-of-service demands. The radio environmental maps are used to calculate the radio coverage and signal strength. In addition, we present the developed framework, which can be applied as a tool for the design, modelling, simulation and evaluation of an LTE-A network for emergency use cases and for estimating the system capacity in a dynamic (roll-in, roll-out phase) network deployment. The proposed algorithm is evaluated with the simulation model using possible real use cases (i.e., forest fire, and earthquake in an urban area) in real remote and urban regions of Slovenia.