Effect of waste serpentine on the properties of basic insulating refractories

Basic insulating refractories were fabricated by the pressing route using dead-burned magnesia, pure calcined alumina, expanded perlite, and calcined waste serpentine as starting raw materials in four compositions from F1 to F4. Periclase and forsterite were major phases in F1 and F2 compositions, while spinel was also detected in the XRD patterns of F3 and F4 samples. Quantitative phase analysis showed that F4 sample sintered at 1450?°C has the highest forsterite content among all other samples. On the other hand, it has lower thermal conductivity compared to F1 to F3, and even lower than aluminosilicate IFBs with the same bulk density. It is concluded that forsterite is a highly insulating material, compared to periclase, corundum, periclase-spinel, aluminosilicates, such as mullite, etc.     

Regional water quality management for the Karun–Dez River basin, Iran

To achieve water quality goals in a river basin, a water quality management model (WQMM) has been developed through the geographic information system (GIS) approach and a mathematical water quality model. The developed model has been applied to the Karun and Dez Rivers, where water quality has decreased due to heavy pollutant loads from Khuzestan province cities and surrounding areas. Pollution sources, land use, geographic features and measured water quality data of the river basin were incorporated into the Arc‐View GIS database. With the database, the management model calculated management type and management cost for each management project in the river basin. Until now, river management policy for polluted rivers in Iran first penalizes pollution sources and then constructs treatment plants for the pollution sources whose wastewater is released untreated and for which the wastewater quality goal of the Iranian Department of Environment is not met. Different management projects with a time programme were proposed and they were compared with the results of the river quality without any management approach. It became clear that the results based on the management approach were much better than those for the unmanaged condition from the viewpoint of the achievement of water quality goals and cost optimization.     

The excellent photocatalytic activity of novel Cs3PW12O40/WO3 composite toward the degradation of rhodamine B

In this paper, a simple one-pot thermal decomposition method was successfully used to synthesize a novel Cs₃PW₁₂O₄₀/WO₃ composite for the first time. The synthesized composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), FTIR, diffuse reflectance spectroscopy (DRS) and N₂ adsorption-desorption techniques. The photocatalytic activity to degrade RhB molecules over Cs₃PW₁₂O₄₀/WO₃ composite was evaluated under xenon light irradiation. The results indicated the complete degradation of RhB molecules over Cs₃PW₁₂O₄₀/WO₃ composite after 30?min irradiation. However, the photocatalytic degradation of RhB over WO₃ and Cs₃PW₁₂O₄₀ after 80?min light irradiation are nearly 52%, and 68%, respectively. The enhanced photocatalytic activity of Cs₃PW₁₂O₄₀/WO₃ composite compared with WO₃, and Cs₃PW₁₂O₄₀ was ascribed to the strong interaction between WO₃ and Cs₃PW₁₂O₄₀, which effectively reduces the recombination of photogenerated electron-hole pairs. Based on experimental results, the possible mechanism of photocatalytic reactions on the Cs₃PW₁₂O₄₀/WO₃ composite photocatalyst was investigated, and the hydroxyl radical (OH) and superoxide radical (O₂^?) were determined as the main active species in the photocatalytic degradation of RhB over Cs₃PW₁₂O₄₀/WO₃ composite.     

Evaluation of lubricant condition and engine health based on soft computing methods

Neural Computing and Applications - Evaluating the condition of the lubricant plays an influential role in the maintenance engineering of mechanical systems. This study has several objectives and...     

A digital frequency independent phase meter

A digital, frequency-independent phase meter is described. It makes use of pulses derived from the multiplication of the frequency of the reference input signal as its clock pulses instead of conventional crystal controlled clock generators. Advantages of the meter include simplicity and the elimination of gating error. The main source of error for this circuit is harmonic distortion of the input signals     

A high resolution digital frequency meter for low frequencies

A digital frequency meter using frequency multiplication is described. It can be used in utility power system control centers and other low-frequency applications where resolutions of the order of 1/100 Hz and almost instantaneous readouts are essential. Possible improvements of the circuit are suggested     

Effect of Notch Location on Fatigue Life Prediction of Strength Mismatched HSLA Steel Weldments

Welding of high strength low alloy steels (HSLA) involves usage of low, even and high strength filler materials (electrodes) than the parent material depending on the application of the welded structures and the availability of the filler material. In the present investigation, the fatigue crack growth behaviour of weld metal (WM) and heat affected zone (HAZ) regions of under matched (UM), equal matched (EM) and over matched (OM) joints has been studied. The base material used in this investigation is HSLA-80 steel of weldable grade. Shielded metal arc welding (SMAW) process has been used to fabricate the butt joints. Centre cracked tension (CCT) specimen has been used to evaluate the fatigue crack growth behaviour of the welded joints. Fatigue crack growth experiments have been conducted using servo hydraulic controlled fatigue testing machine at constant amplitude loading (R=0). A method has been proposed to predict the fatigue life of HSLA steel welds using fracture mechanics approach by incorporatin     

Synthesis and Characterization of New Poly(ether-amide-imide)/Amino-Functionalized Fe3O4 Nanocomposites

New poly(amide-imide)/amino functionalized Fe₃O₄ nanocomposites were successfully fabricated through solution intercalation technique. A poly(amide-imide) derived from an imide-containing diacid and ether linkage diamine was synthesized and characterized. Aiming to have better compatibility, the hydrophilic nature of Fe₃O₄@SiO₂ was changed into organophilic using N-[3-(trimethoxysilyl)propyl]ethylenediamine. The amino-functionalized Fe₃O₄ showed well dispersion in the poly(amide-imide) matrix. Thermal gravimetric analysis results indicated that char yields of the nanocomposites were improved. Microscale combustion calorimetry results showed that poly(amide-imide) had good flame retardancy and amino-functionalized Fe₃O₄ has further improved this property of poly(amide-imide).     

Developing a Model for Decision-Makers in Dynamic Modeling of Urban Water System Management

Water managers may modify many components of urban water systems to minimize water shortage. Since each modification activity has its own positive and negative effects, it is necessary to define an appropriate procedure to predict the consequences of each action. As the parameters of urban water supply and demand system have internal relationships in the time domain, a dynamic model is needed to forecast the result of changes and select the best modification activity. Here the Vensim® is applied as a modeling tool to choose the most effective water management activities in Tehran province. It has been found that the annual increase rate of water tariff by 16.4% and assigning 4.5% of revenue on reducing non-revenue water may be the most effective demand management activity to reduce water shortage in Tehran province. It has also been revealed that, even by implementing the most effective demand management activities in Tehran, the amount of required water in the next 10 years is more than the sustainable capacity of its resources and activities like seawater desalination are inevitable to prevent unsustainable use of water sources.

     

Calculating Price Elasticity of Water Demand Using Gene Expression Programming Based on Economic,Social and Meteorological Variables

Determining the changing rate of water consumption through altering parameters such as water tariffs can help water companies select appropriate water policies. This paper is intended to find the proper relation between the water price elasticity of demand and some social, economic and climatic variables that are released annually by international organizations like the United Nations Development Program and the World Bank. By using genetic algorithm, different combinations of water price elasticity of demand and variables like gross domestic product, per capita gross domestic product, gross national income, precipitation, human development index, average temperature and household size have been analyzed. It was found that the absolute price elasticity of water demand has positive relationships with precipitation and price of water. It has also been found that the gross national income, average percent of consumers who have secondary education and human development index have a negative relation with the absolute price elasticity of water demand.