Hearing damage in workers in a paving and stone-cutting industry

U sklopu sistematskog pregleda radnika u jednoj građevinskoj radnoj organizaciji izvršili smo audiometrijska mjerenja u radnika izvrgnutih buci. Analizirali smo i intenzitet sveukupne buke na radnim mjestima i obavili spektralnu analizu buke. Nalaz audiograma bio je uredan u otprilike polovice svih radnika. S obzirom na to da nismo imali kontrolnih audiograma prije stupanja na rad u ovu industriju, ne možemo ustvrditi da su nađena oštećenja uzrokovana isključivo bukom na tim radnim mjestima. Ovi nalazi, međutim, upućuju na nužnost prethodnog audiometriranja svakog radnika prije njegova stupanja na posao gdje će biti izvrgnut buci.Within a periodical medical check-up of workers in a building enterprise we carried out an audiometric examination in the workers exposed to noise. We analyzed the total noise level at work places and carried out a spectral analysis of noise. The audiograms were normal in about one half of the workers. Since there were no control audiograms before the workers started to work in this industry, we cannot claim that the observed damages were due exclusively to noise. However, the results suggest a necessity of audiometric examinations of workers before they start work in exposure to noise

Assessing the level of understanding of contractors regarding the workers' productivity in construction industry

Productivity of workers is important to enhance the completion of the project within the required time and quality. Majority of the project elements and activities are based on labour performance. Construction activities are recognized as labour-intensive as it rely more on human efforts. Contractors have duties to handle the work in it best way for increasing the quality and decreasing time and also cost. Frequently, at construction sites it is observed that contractors do not pay attention to the productivity of workers and its effect on the overall productivity. Usually they do not measure labour productivity in the construction projects and also they cannot compare productivity rates in the construction sites. The aim of this study is to assess the level of understanding of contractors regarding the workers’ productivity in construction industry of Iran. The data is collected through questionnaires and interviews. The data is analysed using Average Index and SPSS. From the study, the level of understanding of contractors regarding the workers’ productivity in construction industry is “Understand”. The contractors understand the impact of productivity on cost, time and quality

Insight into nano-chemical enhanced oil recovery from carbonate reservoirs using environmentally friendly nanomaterials

The use of nanoparticles (NPs) in enhanced oil recovery (EOR) processes is very effective in reducing the interfacial tension (IFT) and surface tension (ST) and altering the wettability of reservoir rocks. The main purpose of this study was to use the newly synthesized nanocomposites (KCl / SiO2 / Xanthan NCs) in EOR applications. Several analytical techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) were applied to confirm the validity of the synthesized NCs. From the synthesized NCs, nanofluids were prepared at different concentrations of 100-2000 ppm and characterized using electrical conductivity, IFT, and ST measurements. From the obtained results, it can be observed that 1000 ppm is the optimal concentration of the synthesized NCs that had the best performance in EOR applications. The nanofluid with 1000 ppm KCl / SiO2 / Xanthan NCs enabled reducing the IFT and ST from 33 and 70 to 29 and 40 mN/m, respectively. However, the contact angle was highly decreased under the influence of the same nanofluid to 41° and the oil recovery improved by an extra 17.05 % OOIP. To sum up, KCl / SiO2 / Xanthan NCs proved highly effective in altering the wettability of rocks from oil-wet to water-wet and increasing the cumulative oil production

Synthesis, characterization, and assessment of a CeO2@Nanoclay nanocomposite for enhanced oil recovery

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. In this paper, synthesis and characterization of a novel CeO2 /nanoclay nanocomposite (NC) and its effects on IFT reduction and wettability alteration is reported in the literature for the first time. The NC was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), and EDS MAP. The surface morphology, crystalline phases, and functional groups of the novel NC were investigated. Nanofluids with different concentrations of 100, 250, 500, 1000, 1500, and 2000 ppm were prepared and used as dispersants in porous media. The stability, pH, conductivity, IFT, and wettability alternation characteristics of the prepared nanofluids were examined to find out the optimum concentration for the selected carbonate and sandstone reservoir rocks. Conductivity and zeta potential measurements showed that a nanofluid with concentration of 500 ppm can reduce the IFT from 35 mN/m to 17 mN/m (48.5% reduction) and alter the contact angle of the tested carbonate and sandstone reservoir rock samples from 139◦ to 53◦ (38% improvement in wettability alteration) and 123◦ to 90◦ (27% improvement in wettability alteration), respectively. A cubic fluorite structure was identified for CeO2 using the standard XRD data. FESEM revealed that the surface morphology of the NC has a layer sheet morphology of CeO2/SiO2 nanocomposite and the particle sizes are approximately 20 to 26 nm. TGA analysis results shows that the novel NC has a high stability at 90◦C which is a typical upper bound temperature in petroleum reservoirs. Zeta potential peaks at concentration of 500 ppm which is a sign of stabilty of the nanofluid. The results of this study can be used in design of optimum yet effective EOR schemes for both carbobate and sandstone petroleum reservoirs

Application of a novel green nano polymer for chemical EOR purposes in sandstone reservoirs: Synergetic effects of different fluid/fluid and rock/fluid interacting mechanisms

In this research, a novel natural-based polymer, the Aloe Vera biopolymer, is used to improve the mobility of the injected water. Unlike most synthetic chemical polymers used for chemical-enhanced oil recovery, the Aloe Vera biopolymer is environmentally friendly, thermally stable in reservoir conditions, and compatible with reservoir rock and fluids. In addition, the efficiency of the Aloe Vera biopolymer was investigated in the presence of a new synthetic nanocomposite composed of KCl-SiO2-xanthan. This chemically enhanced oil recovery method was applied on a sandstone reservoir in Southwest Iran with crude oil with an API gravity of 22°. The Aloe Vera biopolymer’s physicochemical characteristics were initially examined using different analytical instruments. The results showed that the Aloe Vera biopolymer is thermally stable under reservoir conditions. In addition, no precipitation occurred with the formation brine at the salinity of 80,000 ppm. The experimental results showed that adding ethanol with a 10% volume percentage reduced interfacial tension to 15.3 mN/m and contact angle to 108°, which was 52.33 and 55.56% of these values, respectively. On the other hand, adding nanocomposite lowered interfacial tension and contact angle values to 4 mN/m and 48°, corresponding to reducing these values by 87.53 and 71.42%, respectively. The rheology results showed that the solutions prepared by Aloe Vera biopolymer, ethanol, and nanocomposite were Newtonian and fitted to the Herschel-Bulkley model. Finally, core flooding results showed that the application of a solution prepared by Aloe Vera biopolymer, ethanol, and nanocomposite was effective in increasing the oil recovery factor, where the maximum oil recovery factor of 73.35% was achieved, which could be attributed to the IFT reduction, wettability alteration, and mobility improvement mechanisms

Hearing damage in workers in a paving and stone-cutting industry

U sklopu sistematskog pregleda radnika u jednoj građevinskoj radnoj organizaciji izvršili smo audiometrijska mjerenja u radnika izvrgnutih buci. Analizirali smo i intenzitet sveukupne buke na radnim mjestima i obavili spektralnu analizu buke. Nalaz audiograma bio je uredan u otprilike polovice svih radnika. S obzirom na to da nismo imali kontrolnih audiograma prije stupanja na rad u ovu industriju, ne možemo ustvrditi da su nađena oštećenja uzrokovana isključivo bukom na tim radnim mjestima. Ovi nalazi, međutim, upućuju na nužnost prethodnog audiometriranja svakog radnika prije njegova stupanja na posao gdje će biti izvrgnut buci.Within a periodical medical check-up of workers in a building enterprise we carried out an audiometric examination in the workers exposed to noise. We analyzed the total noise level at work places and carried out a spectral analysis of noise. The audiograms were normal in about one half of the workers. Since there were no control audiograms before the workers started to work in this industry, we cannot claim that the observed damages were due exclusively to noise. However, the results suggest a necessity of audiometric examinations of workers before they start work in exposure to noise

Design methodology of the high performance large-grain polysilicon MOSFET

A methodology to design high-performance MOSFETs on the large-grain polysilicon-on-insulator (LPSOI) film is presented. Due to the metal-induced lateral crystallization (MILC) process in the formation of LPSOI films, the polysilicon grain locations and orientations can be reasonably controlled. Therefore, the performance of an LPSOI MOSFET can be optimized by carefully selecting the orientation and grain location according to the size of the desired transistor. The effects of various design parameters including the distance from the nickel strip, relative source/drain position, transistor orientation, and layout geometry are investigated. A ladder layout method is proposed to provide scalability in the design of high performance LPSOI MOSFETs. A design guideline for designing LPSOI NMOSFETs with different dimensions is given

Analysis of aligned polysilicon grain boundaries effects on the performance of large-grain polysilicon MOSFET

Aligned polysilicon grain boundaries effects on the performance of the MOSFET fabricated on Large-grain Polysilicon-On-Insulator (LPSOI) have been investigated. The LPSOI film of grain size ranging from 10 to 100μm is formed from amorphous silicon using MILC (metal induced lateral crystallization) and subsequent high temperature annealing. The grain boundaries (GBs) are found parallel to the crystallization direction and it is possible to align these GBs parallel (longitudinal) and perpendicular (latitudinal) to the direction of current flow in the channel region. The parallel GBs have shown minimum impedance to the conduction carriers, thus the parallel GB'S devices are maintaining the high drive current, low threshold voltage, and steep subthreshold slope. However, it is the source of higher leakage current in the off-state, which causes an early device shortage especially in wide devices. On the other hand, perpendicular GBs in the channel region have shown high impedance to the conduction carriers that result in higher threshold voltage, lower current drive, and gentle subthreshold slope. A significant improvement in the device performance has been obtained with scaling. This analysis provides the guideline for the high performance LPSOI circuits for 3-D application

High frequency performance of large-grain polysilicon-on-insulator MOSFETs

Large-grain polysilicon-on-insulator (LPSOI) MOSFETs, formed from amorphous silicon by high-temperature metal-induced-lateral-crystallization (MILC) have been reported to operate in gigahertz range for the first time. Large dimensional (W/L 240/1.2 mum) LPSOI NMOSFETs and PMOSFETs display a maximum transconductance (g(m max)) 68 mS/mm and 48 mS/mm at V-DS = 3 V, respectively The unity short circuit current gain frequencies (fr) of NMOSFET and PMOSFET have been found to reach 3.4 GHz and 2.6 GHz at channel length of 1.2 mum. With channel length scaling, higher f(T) can he achieved and have been demonstrated with the measured value of 5.1 GHz f(T) for PMOSFET with a channel length of 0.7 mum. The f(T) value obtained is the highest among silicon FETs fabricated on nonsingle crystal silicon substrates