Effectiveness of Connections Type on Vibration Response of Steel Beam

In a steel structure, choosing the connections type are one of the most important parameters in design consideration. How a connection type affects the vibration of steel beams has been investigated in this paper. The most effective connection type in reducing beam vibration has been highlighted. The study was conducted using different finite element models to simulate each connection type. Firstly, the model was validated by comparing its results with the results obtained by the analytical approach. In the numerical model, a linear frequency analysis was performed to determine beam natural frequency, then it has been compared with the corresponding value obtained by the Euler-Bernoulli approximations for simply supported beams. After that, two analysis procedures have been executed, steady-state analysis and transient analysis. In the steady-state analysis, a harmonic load with different frequencies was applied to the beam mid-span, while an impulsive load has been applied in the transient analysis. The results indicate that the deflection could be reduced by 72%, furthermore steady vibration of the beam can be reduced by 81% with using one of the moment connections instead of the traditional shear connection

Synthesis and Physicochemical Behaviour of Polyurethane-Multiwalled Carbon Nanotubes Nanocomposites Based on Renewable Castor Oil Polyols

Polyurethanes (PUs) are high performance materials, with vast industrial and engineering applications. In this research, effects of Multiwalled Carbon Nanotubes (MWCNTs) on physicochemical properties of Castor Oil based Polyurethanes (COPUs) were studied. MWCNTs were added in different weight percentages (0% to 1% wt) in a castor oil based polyurethane (COPUs-MWCNTs) nanocomposites. The composition, structure, and morphology of polyurethanes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), and element detection by energy dispersive spectroscopy (EDX) analysis, respectively. Thermal stability was studied by thermogravimetric analysis (TGA). Barrier properties and surface area studies were investigated by nitrogen permeability machine and BET technique. Mechanical properties were calculated by tensile universal testing machine. Results showed well dispersed MWCNTs in polyurethane matrix at different weight percentages. The best results were obtained with 0.3 wt% of MWCNTs in the composite. Surface area studies revealed presence of very few pores which is in a good agreement with barrier permeability, reduced up to ~68% in 1 wt% and ~70% in 0.5 wt% of MWCNTs in polymer matrix, with respect to pure COPUs samples

Determination of economic injury level of Lipaphis erysimi (Hemiptera: Aphididae) on canola var. Hayola 401 in Khuzestan

Canola, an oil seed with high contents of oil, is a major farming in Khuzestan province, where there is an increase over its cultivation year by year. One of the canola key pests is mustard aphid (Lipaphis erysimi Kalt.) in this province. However, there was not available information on the economic injury level (EIL) of the pest that is much vital for correct decision making on pest control. Therefore, a study on EIL was conducted through complete randomized block design with 5 replications and 11 treatments (0, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 aphid per central stem of Hayola 401 variety of canola) inside a netted cage. This research was conducted in Behbahan Agricultural Research Station during 2004-2006. The average of seed yield and also the yeild components was analyzed with Duncanâs multiple range tests. The damage of the aphid was estimated by regression equation. The injury level was estimated by Grain threshold method. The results indicated that EIL was 7.53 and 2.49 cm aphid per central stem of canola in Behbahan region in 2004-2005 and 2005-2006, respectively. Economic threshold (ET) was 5.65 and 1.87 cm2 aphid per central stem of canola

Mechanical and thermal properties of the waste low and high density polyethylene-nanoclay composites

In extension with the previous work, recycling of the waste polyolefins by dissolution/reprecipitation method, has been investigated. The goal of study was to explore the influence of organo-modified/unmodified sodium montmorillonite clays, on the behaviours of waste polyolefins inclusive low density polyethylene (LDPE) and high density polyethylene (HDPE). 1-5 wt % of unmodified (MMT) and Organo-modified clay (OMMT) were added to the polyolefins, to prepare polyolefin-clay nanocomposites by melt intercalation method. X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) were used to estimate the dispersion of clay in the polymer matrices and the morphology of nanocomposites. Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) were used to analyse the change in the thermic properties of the waste polyolefins nanocomposites. The XRD and FESEM results showed an intercalated structure in the HDPE and LDPE with Organo-clay nanocomposites, whereas no exfoliation was observed with unmodified clay in both waste HDPE and LDPE, respectively. DSC and TGA, showed an improved thermal behaviours in the HDPE/Organo-clay nanocomposites (3 wt%) clay loading. Melting temperature and crystallization percentage were observed to increase in 1, 2, and 3 wt% loadings. In waste LDPE/clay nanocomposites, no improvement was established in the thermal stability

Opportunities and challenges in the use of coal fly ash for soil improvements – a review

Coal fly ash (CFA), a by-product of coal combustion has been regarded as a problematic solid waste, mainly due to its potentially toxic trace elements, PTEs (e.g. Cd, Cr, Ni, Pb) and organic compounds (e.g. PCBs, PAHs) content. However, CFA is a useful source of essential plant nutrients (e.g. Ca, Mg, K, P, S, B, Fe, Cu and Zn). Uncontrolled land disposal of CFA is likely to cause undesirable changes in soil conditions, including contamination with PTEs, PAHs and PCBs. Prudent CFA land application offers considerable opportunities, particularly for nutrient supplementation, pH correction and ameliorating soil physical conditions (soil compaction, water retention and drainage). Since CFA contains little or no N and organic carbon, and CFA-borne P is not readily plant available, a mixture of CFA and manure or sewage sludge (SS) is better suited than CFA alone. Additionally, land application of such a mixture can mitigate the mobility of SS-borne PTEs, which is known to increase following cessation of SS application. Research analysis further shows that application of alkaline CFA with or without other amendments can help remediate at least marginally metal contaminated soils by immobilisation of mobile metal forms. CFA land application with SS or other source of organic carbon, N and P can help effectively reclaim/restore mining-affected lands. Given the variability in the nature and composition of CFA (pH, macro- and micro-nutrients) and that of soil (pH, texture and fertility), the choice of CFA (acidic or alkaline and its application rate) needs to consider the properties and problems of the soil. CFA can also be used as a low cost sorbent for the removal of organic and inorganic contaminants from wastewater streams; the disposal of spent CFA however can pose further challenges. Problems in CFA use as a soil amendment occur when it results in undesirable change in soil pH, imbalance in nutrient supply, boron toxicity in plants, excess supply of sulphate and PTEs. These problems, however, are usually associated with excess or inappropriate CFA applications. The levels of PAHs and PCBs in CFA are generally low; their effects on soil biota, uptake by plants and soil persistence, however, need to be assessed. In spite of this, co-application of CFA with manure or SS to land enhances its effectiveness in soil improvements

Synthesis and Physicochemical Behaviour of Polyurethane-Multiwalled Carbon Nanotubes Nanocomposites Based on Renewable Castor Oil Polyols

Polyurethanes (PUs) are high performance materials, with vast industrial and engineering applications. In this research, effects of Multiwalled Carbon Nanotubes (MWCNTs) on physicochemical properties of Castor Oil based Polyurethanes (COPUs) were studied. MWCNTs were added in different weight percentages (0% to 1% wt) in a castor oil based polyurethane (COPUs-MWCNTs) nanocomposites. The composition, structure, and morphology of polyurethanes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), and element detection by energy dispersive spectroscopy (EDX) analysis, respectively. Thermal stability was studied by thermogravimetric analysis (TGA). Barrier properties and surface area studies were investigated by nitrogen permeability machine and BET technique. Mechanical properties were calculated by tensile universal testing machine. Results showed well dispersed MWCNTs in polyurethane matrix at different weight percentages. The best results were obtained with 0.3 wt% of MWCNTs in the composite. Surface area studies revealed presence of very few pores which is in a good agreement with barrier permeability, reduced up to ~68% in 1 wt% and ~70% in 0.5 wt% of MWCNTs in polymer matrix, with respect to pure COPUs samples

Synthesis and Characterization of Polyurethane– Organoclay Nanocomposites Based on Renewable Castor Oil Polyols

In this study, castor oil-based polyurethanes–organoclay (COPUs-Cloisite 30B) nanocomposites are synthesized by mixing polypropylene glycol polyol and dehydrated castor oil (15 %), enforced with C30B nanofillers, at different weight percentages. The physico-chemical behaviors were evaluated by Fourier transform infrared spectroscopy, Fourier scanning electron microscopy, scanning electron microscopy and X-ray diffraction. Thermal stability was found improved up to ~30 °C in the sample with 5 wt% of C30B. Tensile properties depicted an improvement of ~240 % in tensile strength and decrease of ~30 % in elongation with 5 wt% organoclay, respectively. Improved physico-chemical properties of COPUs-C30B signify the usage of COPUs-C30B in the industrial and commercial applications, i.e. coatings, adhesives and automotive applications

Pure Polyurethane and Castor Oil Based Polyurethane: Synthesis and Characterization

In this study, the physico-chemical properties of high performance polyurethane synthesized from poly propylene glycol (PPG) in comparison with a combination of PPG and castor oil, is studied using the in-situ polymerization technique. The variations in properties of both types of polyurethanes are evaluated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and the thermogravimetric analysis (TGA) technique. Tensile strength properties were investigated by film tensile testing equipment. The results indicated the presence of large -CH stretching in the castor oil mixed polyurethane with a larger oxidative thermal stability over pure PPG polyurethanes. The tensile properties were found to be almost comparable in pure and mixed polymers, signifying the usage of mixed polymers in the future to overcome the environmental and economic crisis in polyurethane synthesi

Iron oxide magnetic nanoparticles: a short review

Magnetic nanoparticles have been enjoying great importance and wide scale applications during the last two decades due to their specific characteristics and applications. Iron oxide magnetic nanoparticles with appropriate surface chemistry have been implied in numerous applications such as biomedicine and cancer therapy, catalysis and in magnetic separation techniques. This review summarizes recent commercial, industrial and bio-engineering applications and brief study of the methods for the preparation of iron oxide magnetic nanoparticles with a control over the size, morphology and the magnetic properties. Some future applications of microwave irradiation for magnetic particle synthesis are also addressed