Investigation on local and average static hold‐ups in liquid–liquid systems in a rotary disc contactor

A rotating disc contactor with inner diameter of 91 mm and 21 compartments was used to investigate local and average static hold‐ups in the column. Three chemical systems, including distilled water as stagnant continuous phase and toluene, kerosene, and butyl acetate as dispersed phase, in case of no mass transfer, were applied. Different parameters consisting of drop size and static hold‐up were measured experimentally under various operating conditions, and two dimensionless correlations for estimation of local static hold‐up as a function of average mother drop size, physical properties, rotor speed, and stage number were proposed in two cases: (1) immovable and (2) rotating rotor discs. Furthermore, two dimensionless correlations were presented to estimate average static hold‐up as a function of average mother drop size, physical properties, rotor speed, and number of stages in the column in the two aforementioned conditions.     

Text Classification for Azerbaijani Language Using Machine Learning

Text classification systems will help to solve the text clustering problem in the Azerbaijani language. There are some text-classification applications for foreign languages, but we tried to build a newly developed system to solve this problem for the Azerbaijani language. Firstly, we tried to find out potential practice areas. The system will be useful in a lot of areas. It will be mostly used in news feed categorization. News websites can automatically categorize news into classes such as sports, business, education, science, etc. The system is also used in sentiment analysis for product reviews. For example, the company shares a photo of a new product on Facebook and the company receives a thousand comments for new products. The systems classify comments like positive or negative. The system can also be applied in recommended systems, spam filtering, etc. Various machine learning techniques such as Naive Bayes, SVM, Multi-layer Perceptron have been devised to solve the text classification problem in Azerbaijani language.     

Hydrogen Production from Co‐Gasification of Coal and Biomass in the Presence of CaO as a Sorbent

Among the options for clean energy production, the gasification process is receiving increasing attention as it offers the best combination of investment and value of produced electricity compared to other methods. An Aspen Plus model of co‐gasification of biomass and coal with in situ CO₂ capture was developed to evaluate its potential for hydrogen production and cracking of organic impurities, i.e., tars. The effects of some critical operational variables on gas composition and yields of hydrogen gas and tar were investigated. The obtained results indicate that the fuel particle size plays a minor role in the process; smaller particles favor the conversion of tar and production of more hydrogen gas.     

Preparation of quaternary boro-phosphate multifunctional glasses and their structural,optical, switching and antibacterial properties

In this paper, the glass composition of (50-x)P₂O₅-xB₂O₃-30CuO-20Li₂O (x?=?0, 5, 10, 15, and 20?mol%) was prepared and the effect of P₂O₅ substitution by B₂O₃ on their structural, optical, switching, and antibacterial characteristics was studied. FT-IR spectra showed that an increase in the B₂O₃ content leads to gradual erosion of the phosphate characteristic bonds, and the emergence of borate-related ones by creating new linkages between phosphate chains through P–O–B bonds and formation of highly cross-linked P³-O-B⁴ linkages. The incorporation of boron up to 20?mol%, also leads to an overall increase in glass transition temperature together with a decrease in the molar volume which both, implied improvement of glass stability. Optical studies revealed that all glasses are almost transparent in the UV–Vis region with high band gap energy about 3.83?eV, which experiences a red-shift with increase in the B₂O₃ concentration to 15?mol%. By calculating the wavelength-dependent optical parameters, however, it was found that the present glass composition with highest concentration of B₂O₃ shows refractive index near one and very negligible extinction coefficient (and imaginary optical dielectric function) at the visible region. These results support the great potential of the mentioned glass composition as a window layer. The analysis of the high electric field measurements demonstrated a wide range reduction in switching threshold voltage as the B₂O₃ content increases. This hints at their potential application as electrical-induced sensors. The antibacterial activity of x?=?0 and x?=?5 glass compositions has been examined by zone of inhibition measurements and it was found that they have potential applications as antibacterial agent.     

Synthesis and characterization of supported heteropolymolybdate nanoparticles between silicate layers of Bentonite with enhanced catalytic activity for epoxidation of alkenes

A new heterogeneous catalyst (PVMo/Bentonite) consisting of vanadium substituted heteropolymolybdate with Keggin-type structure Na₅[PV₂Mo₁₀O₄₀]·14H₂O (PVMo) supported between silicate layers of bentonite has been synthesized by impregnation method and characterized using X-ray diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy, UV–vis diffuse reflectance spectroscopy, transmission electron microscopy and elemental analysis. X-ray diffraction and scanning electron microscopy analysis indicated that PVMo was finely dispersed into layers of bentonite as support. The PVMo/Bentonite used as an efficient heterogeneous catalyst for epoxidation of alkenes. Various cyclic and linear alkenes were oxidized into the corresponding epoxides in high yields and selectivity with 30% aqueous H₂O₂. The catalyst was reused several times, without observable loss of activity and selectivity. The obtained results showed that the catalytic activity of the PVMo/Bentonite was higher than that of pure heteropolyanion (PVMo).     

Economic and air pollution effects of city council legislations on renewable energy utilisation in Tehran

Regarding the application of renewable energies, their infiniteness and no pollutant production are two important reasons for the universal acceptance. In this issue, calculation of the initial capital cost and the payback time are of crucial importance. Considering the significance of air pollution problem in the metropolis of Tehran and its related challenges, the Iranian government has been required to apply renewable sources. This research deals with the investigation of environmental and economic aspects, implementation of Tehran City Council Legislation (TCCL) considering the provision of 10–20% of required energies from new energies in buildings which were given permission in 2014. A large amount of the energy is consumed for different purposes such as water heating and to provide this need, a solar water heater (SWH) can be applied. In fact, by implementation of TCCL, the annual profit obtained by exporting extra natural gas to the neighbouring countries is 210,939.25$, which is a result of preserving 421,878.5?m³ natural gas. Furthermore, production of pollutants such as CO₂, SO₂, and NO_x reduced by 3045.40, 14.540, and 11.111 tons, respectively. Hence, reduction of environmental costs was calculated as 150,956.25$. Eventually, calculation of payback time for implementing SWH was obtained as 17 months.     

Evaluating knowledge management failure factors using intuitionistic fuzzy FMEA approach

The twenty-first century organizations are characterized by an emphasis on knowledge and information. Today’s organizations also require the acquisition, management, and exploitation of knowledge and information in order to improve their own performance. In the current economy, the foundations of organizational competitiveness have turned former tangible and intangible resources into knowledge and the focus of information systems has also changed from information management to knowledge management. Besides, the most important step in the implementation of knowledge management is to examine the significant factors in this regard and to identify the causes of failure. Therefore, the present study evaluated knowledge management failure factors in an intuitionistic fuzzy environment as a case study in Khuzestan Oil and Gas Company. For this purpose, a series of failure factors affecting knowledge management in organizations were identified based on a review of the related literature and similar studies. Then, 16 failure factors in the implementation of knowledge management in the given organization were determined on the basis of interviews with company experts. According to the specified factors as well as the integration of multiple criteria decision-making techniques in an intuitionistic fuzzy environment, knowledge management failure factors in Khuzestan Oil and Gas Company were investigated. The results indicated that lack of management commitment and leadership was the most important factor affecting the failure of knowledge management in the given company.     

Experimental and theoretical investigation of thermal conductivity of some water-based nanofluids

Modified transient plane source method has been applied for thermal conductivity measurements of three water-based nanofluids containing Al₂O₃, TiO₂, and graphene nanoparticles. Experiments were conducted at different temperatures and concentrations. The effects of sort of nanoparticles, concentration, and diameter of nanoparticles as well as temperature were studied by comparing the experimental results with the predictions of ten preceding models. The overall performances of these models were compared in terms of percent error. Percent errors were observed in the current study ranging from vicinity of zero up to nearly 110% that belonged to Bruggeman model in predicting the thermal conductivity ratio of graphene/water nanofluids. All ten models performed acceptably in calculating thermal conductivity ratio of Al₂O₃ nanofluids with the maximum percent error of 2.16%. Four correlations are proposed based on the experimental results of this work three of which are special to each nanofluid and the fourth one is overall. These models succeeded to predict the thermal conductivity ratio of the studied nanofluids with considerably lower percent errors which was maximum 5.19% observed in predicting the thermal conductivity ratio of graphene/water nanofluid.     

Improvement in physical and mechanical properties of aluminum/zircon composites fabricated by powder metallurgy method

Metal–matrix composites (MMCs) are known as the most useful and high-tech composites in our world as well as aluminum (Al) as the best metal for producing these composites. Combining aluminum and zircon (ZrSiO₄) will yield a material with the best corrosive resistance and mechanical properties like strength at high temperatures. Also, the abrasive wear behavior of these composites will be improved. In the present investigation, a study on aluminum/zircon composites has been carried out. Micro-structures of these composites in powder metallurgy conditions show different size distribution of zircon with different proportions in the composite. Also, there is a case-study about density and compressive strength and hardness of aluminum/zircon composites. The green specimens prepared by isostatic pressing of prepared powders with different zircon percentages, were sintered at two temperatures. These specimens were then investigated by different physical and mechanical testing methods to observe in which conditions the best properties would be obtained. The most improved compression strength was obtained with the specimen including 5% of zircon sintered at 650 °C.     

Sonochemical Synthesis of One-Dimensional Nano-structure of Three-Dimensional Cadmium(II) Coordination Polymer

Nano-wires and nano-rods of a new three-dimensional cadmium(II) coordination polymer, {[Cd₃(3-pyc)₄(NCS)₂(H₂O)₄]·2H₂O} _n (1); 3-Hpyc = 3-pyridinecarboxilic acid, were synthesized by a sonochemical method in two different concetrations. The morphology of the nano-structures depend strongly on reactants’ concentration. The new nano-structures were characterized by scanning electron microscopy, X-ray powder diffraction, elemental analyses and IR spectroscopy. Compound 1 was structurally characterized by single-crystal X-ray diffraction and is a three-dimensional polymer with two types of Cd(II) coordination environments.