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One of the most important factors in the economic development of countries is the growth of the foreign sector of the international economy and trade. In other words, having extensive trade exchanges is one of the main factors of the economic growth of countries. In this regard, one of the new topics in the field of organizations is the application of the concepts of digitalization and information technology in the management of service and production organizations which take place in the fourth industrial revolution. The purpose of this study is to evaluate the current situation of Iran's customs in terms of the components of the Fourth Industrial Revolution. The current study is applied research because in addition to the scientific aspect, it will also have a practical aspect for companies and organizations, especially customs. In terms of method, the present study is quantitative research examining the current situation, the obtained data are classified into seven main categories: Utilization of modern technologies, facilities and infrastructure, cooperation and interaction, policies and laws, management and planning, international and external factors and the structure of the organization. The results showed that the current situation of customs has been favorable in terms of the components of the fourth industrial revolution.

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Optical properties of graphene oxide and poly methyl methacrylate nanocomposite was investigated in this paper. Initially, graphene oxide was prepared from the oxidation of graphite powder by a strong acid by Hummers-Offemane method. Then identification, purity determination and particle size were obtained by using infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The average size of graphene oxide nano particles was estimated about 38.4 nm using the XRD technique. So nano composites of graphene oxide based on poly methyl methacrylate were prepared by the co-precipitation method as an optical sensor element. Nano  composites were identified and characterized by FE SEM, EDX, XRD and FT IR analyzes. To investigate the optical properties of the specimens, UV-vis spectro photometry and reflective spectrometer were used. For three samples of the poly methyl methacrylate nano composite containing nano -graphene oxide, the values ​​of the color parameters b *, a * and L * were obtained that were prepared in the same conditions. Then the black index of the Westlanchr('39')s ratio was calculated. The average blackness index calculated was 3.7 for this nano composite. The study of UV-vis spectra in the region of 400-1100 nm for this nano composite showed that in the 400 - 700 nm regions the light transmission of UV light is approximately zero. Therefore, the results showed that the use of graphene oxide in the PMMA matrix improves the nano composite coating properties against UV waves and nano oxide graphene gives better shades of black color compared to other fillers and pigments.

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Lovastatin is a potent agent for lowering cholesterol of blood. Since one of the main reasons of mortality in developing countries is cardiovascular disease, which is caused by precipitation of fatty acid (especially cholesterol) in blood vessels; therefore diets containing lovastatin may prevent this type of disease. In this study, Lovastatin, monacolin K or competitive inhibitor of the HMG-CoA reductase (operative enzyme for cholesterol synthesis) was produced by submerged fermentation using Monascus purpureus PTCC5303. Seven chemical and nutritional parameters including maltose, peptone, MgSO4.7H2O, MnSO4.H2O, KH2PO4, thiamin and pH screened using Plackett Burman experimental design for monacolin production. Among different parameters, maltose and MgSO4.7H2O showed significant effect on biomass and monacolin production. The concentration of these agents were optimized using response surface methodology for lovastatin production in the shaker flask. The optimized medium contained 26 g/L maltose, 5 g/L peptone, 0.1 g/L MgSO4.7H2O, MnSO4.H2O 0.5 g/L, 4 g/L KH2PO4, Vitamin B1 0.1 g/L and pH 7. After 10 days of fermentation in the shaker flask with 130 rpm agitation and 30 ºC, we achieved maximum lovastatin production which was 63 mg/l.

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Although regular study of the story plots opened the new way into analysis in literature by the formalists’ studies, especially by Propp's findings, Structural narratologists after Propp, including Greimas, have tried to find a comprehensive pattern for the study of narration by removing some shortcomings of Propp's framework. This article tries to answer these questions by studying Joseph Story in The Quran according to Propp’s and Greimas' views: do Propp's findings conform to The Quran’s Stories? Can these three syntagmes offered by Greimas be found in The Quran’s stories? Analyzing Joseph Story as a sample of The Quran’s stories can decide which of these views is more efficient in the analysis of The Quran’s stories.  The text of the twelfth surah of The Quran has been examined with a descriptive-analytic method. The findings of this study show that: 1) in spite of the fact that Propp's view is capable of analyzing a lot of stories, analyzing The Quran’s stories according to this view requires basic changes in it. 2) Due to the fact that Greimas' syntagmes are not specified for a special kind of narration, they can be found in The Quran’s stories, too. 3) Considering the analysis of Joseph Story as a sample of The Quran’s stories, it can be said that Greimas' view is more efficient in the analysis of The Quran’s stories than Propp's view.
 

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In grinding operation, cutting fluid is utilized for lubrication, cooling, chip removal from contact zone and also cleaning of grinding wheel. Despite these advantages, grinding fluids make many economic and environmental issues. On the other hand, dry grinding generally leading to thermal damages and reduction of surface quality level. Minimum Quantity Lubrication (MQL) technique is a new approach to elimination or reduction of cutting fluids that improves grinding performance by efficient penetration to the cutting zone. In this paper, in order to investigate the effect of MQL on grinding of steels, raw and hardened High Speed Steel have been selected. Grinding performance such as tangential grinding force, friction coefficient, roughness and morphology of the ground surface and chip form in three states of dry, conventional fluid and MQL have been studied and compared. The results show that MQL technique in comparison with the others lead to improvement of surface quality and also reduction of tangential grinding force and friction coefficient in hardened steel, but in the case of raw steel despite of reduction of tangential grinding force and friction coefficient, the surface quality is worst.

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Enriching human food using new technology such as lipid nanocarriers is a simple and accessible tool. Accordingly, the present study aimed to evaluate the sensory and production of healthy and useful food products to evaluate the enrichment of milk with zeaxanthin lipid nanocapsules and to evaluate its cryoprotectants. During experimental-laboratory research, zeaxanthin extraction from Spirulina platensis, and nanocarriers produced for milk enrichment were used as a food model system. Three samples of milk, milk enriched with lipid nanocarriers containing zeaxanthin, and milk enriched with lipid nanocarriers were examined (at similar concentrations of nanocarriers). In order to check the efficiency of produced nanocarriers, cold protective compounds (glucose, sorbitol, glycerin, lactose, and sucrose) were added to milk. Sucrose was recognized as the best cryoprotectants. Sensory evaluation of enriched milk was performed on a five-degree hedonic scale and different sensory parameters were examined. Data were analyzed using Minitab (v. 2016). Results No significant difference was observed between the sensory characteristics of control milk and milk enriched with nanocarriers (P<0.05). The lowest particle size and dispersion index were obtained in the coating of nanocarriers with cold protective compounds, respectively, 320.82 and 0.26 to 0.31. Zeta potential was reported as -6.03. By enriching milk with zeaxanthin-containing nanocarriers, in addition to visual and skin health, problems related to the lack of useful natural additives and insolubility of food products can be eliminated.


 

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Tornado is a destructive phenomenon which causes severe damage every year. To improve resistance of structures which face tornado, the flow field and factors which affect damage patterns of tornado need to be investigated. In this paper, numerical simulations of stationary and translating tornadoes are carried out using Ward-type simulator results and large eddy turbulence model. Validation for stationary case has been done with experimental work of Baker. The effects of peak winds, duration of intense winds and acceleration of translating tornado on damage patterns have been investigated. Results show that destruction is more intense at the side of the tornado that translational velocity and tangential wind velocity are added up. Moreover, peak wind velocity and duration of intense winds are important factors that have important effects on the destruction pattern of tall structures. However, the value of the translational acceleration of tornado is important for the design of all structures regardless of their heights.

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Variation of the cross-sectional area of a channel affects the flow field and, therefore, convective heat transfer between the fluid and channel walls. In this paper, a geometrical model is proposed for a wavy channel carrying steady laminar flow of an incompressible fluid. The two-dimensional channel is modeled as a combination of a number of subsonic diffusers and nozzles. Effects of the geometrical characteristics such as length, boundary shape and symmetry of the channel, which describe the shape of these nozzles and diffusers, are investigated. Numerical studies at Re=200 show that the shape of the wall does not dramatically affect the convection heat transfer rate in the steady laminar regime. However, optimization studies can be carried out to change the shape of the channel and improve the average Nusselt number to some extent. It is shown that the average Nusselt number increases with the increase of the length of the diffuser part, but the asymmetry of the channel might increase or decrease the average Nusselt number. Finally, a genetic algorithm is introduced and used to optimize the geometrical parameters which describe the aforementioned nozzles and diffusers and, hence, the shape of the channel.

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In hydroforming process, applying hydraulic pressure to the inner surface of tube along with axial loads to two ends of tube simultaneously cause the tube to be formed to the die shape. Application of finite element simulation is common practice to predict the geometrical dimensions of the produced part and analysis of probable defects. For finite element simulation, precise mechanical properties of tube material are required. Obtaining these properties from a test similar to the tube hydroforming process is desirable. In this study hydraulic bulge test using T-shape die has been introduced to obtain the stress-strain curve of the tube material. Using hydroforming set-up, several experiments were carried out on C12200 copper samples. Geometrical parameters required to be used in analytical solutions have been identified and the stress-strain curve has been plotted. The results of the proposed experiment have been compared to the results of the tensile test. In addition, the effects of anisotropy on the obtained stress-strain curve of both tests have been determined. The stress-strain curve obtained has been used to plot the forming limit diagram. The bulge test mechanical properties and the forming limit diagram have been applied to simulate the tube bursting and prediction of the final part geometrical dimensions in T-shape tube hydroforming and these results have been compared to the part being experimentally produced by hydroforming. The results show that when stress-strain curve obtained by the proposed experiment is used, there is a good agreement between the simulated hydroformed part and the experimental part.

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In this paper an improved immersed boundary method is used for simulating sinusoidal pitching oscillations of a symmetric airfoil. Immersed boundary methods because of using a fixed Cartsian grid are well suited for such moving boundary problems. Two test cases are used to validate the proposed method and the effects of oscillation frequency and amplitude on the flow field are investigated. Flow field vorticity and kinetic energy contours are reported in this paper. It is found that the deflected wake start to be appeared for Strouhal number more than 0.4 at a fixed pitching amplitude 0.71. A chaotic flow can be observed at oscillation amplitude 2.80, for a fixed Strouhal number, 0.22. Kintic energy contour shows that for Strouhal number 0.1, the airfoil performs work and transfers momentum to flow but the fluid energy loss due to the enlargement of flow separation zone decreases the momentum and kinetic energy behind the airfoil. Deficit momentum and kinetic energy behind the airfoil results in drag force increasing. By increasing the oscillation frequency and amplitude more momentum transfers to flow filed behind the airfoil which results in drag force decreasing.

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Rock dynamics as a branch of rock mechanics deal with dynamic behavior of rocks under high loading rates. Considering that many problems in rock engineering including earthquackes, explosions and projectile penetrations deal with high loading rates, rock dynamics has been of high significance to explore. In order to design and stability analysis of many of defense and military structures constructed on and in rocks, designating of dynamic behavior of rocks under different loading rates is essential. However, detailed understanding of rock dynamics has been of high challenge due to the additional ‘4th’ dimension of time. The split Hopkinson pressure bar test (SHPB) is the most applicable and famous technique in determination of dynamic behavior of materials under high loadin rates. In this thechnique, a pressure wave with a high domain is dispatched to the specimen and the reflected and transmitted waves of specimen will be captured by means of strain gauges glued on the bars of Hopkinson apparatus. A dynamic stress-strain curve will be obtained for the specimen applying some known equations upon physical conditions of SHPB test. A great majority of studies have been shown that dynamic strength of rocks increases with an increase in loading rate. Also, it has been shown that inertial and heterogeneity effects are the most impressive factors on dynamic strength increase of rocks under high loading rates. It is of note that Inertial effect boils down to a sudden increase in inner pressure of rock. Although, heterogeneity causes a more proper dynamic stress equilibrium as well as an increase in strain rate of specimen before the failure relative to those of homogenous one. The more the loading rate is, the more the strength of rock increases. In the present study, efforts have been applied to explore the effect of loading rate on dynamic behavior of rocks using split Hopkinson pressure bar as the most known and common apparatus in studying dynamic behavior of materials under high loading rates. The specimens have been cored of the same block of sandstone with a diameter of 21.5 mm and aspect ratio of 2. First of all, some quasi- static tests including uniaxial and Brezilian have been done to obtain uniaxial compressive strength, Young’s modulus, poison’s ratio and tension strength. In the meantime, Ultra-sonic test has been applyied to group the specimens of same p-wave velocity before doing Hopkinson test. The dynamic stress-strain curves for the specimen under different loading rates have been gained after capturing incident, reflected and transmitted waves by the strain gauges. Results show that there is an intense dependence of dynamic strength of sandstone to the loading rate so that with imposing the strain rate of 150 s^(-1) on the specimen, the dynamic strength of sandstone has been increased to 260 MPa from 160 MPa in quasi-static conditions. That’s why DIF, as the ratio of quasi-static strength to the dynamic one, has been obtained 1.6 at the 150 s^(-1) strain rate.

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In hydroforming process, the curve of internal pressure versus axial feeding is called loading path which is the key to produce a desire product. Finite element simulation of tube hydroforming can be used to study the loading path effect on the final part characteristics. In this research the finite element simulation of pulsating hydroforming process has been done in conjugation with two different work hardening models: an isotropic hardening and a mixed isotropic-nonlinear kinematic hardening model, which is capable to describe the Bauschinger effect. The parameters of both hardening models have been obtained from tensile test data. The result of the both finite element simulations were compared to experimental work. The results show that the mixed hardening model gets better prediction of final product characteristics than isotropic hardening. The differences between the results of two hardening models are from this fact that in a hydroforming process the tensile and compression loads are used and the loads reversal may be occurred. To study the effect of pulsating pressure on tube material characteristic, a three-step bulge test with unloading has been done and the results have been compared to monotonic bulge test. Loading and unloading of internal pressure cause a higher bulge height for a final pressure level compared to monotonic bulge height. The finite element simulation of pulsating hydroforming has been compared to linear hydroforming. The reported bulge heights and thicknesses show an improvement in formability of tubular material in pulsating hydroforming by considering the average pressure level which was applied.

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Consumption of cutting fluids imposes high costs on industry. These cutting fluids contaminate the environment and are harmful to human health. Minimum quantity lubrication technique (MQL) is a new approach to reduction of cutting fluids consumption, improving efficiency of cutting fluid at machining zone and using harmless fluids. However, this technique faces cooling limitation in grinding. The purpose of this study is an accurate study of heat transfer mechanism in minimum quantity lubrication technique by its temperature numerical simulation and improving the cooling ability of its air jet by using a simple and inexpensive vortex tube. For this purpose, a system was designed and manufactured to measure the convection heat transfer coefficient of different conditions of MQL environments. The result of convection heat transfer tests shows 95% share of compressed air in heat transfer and also air pressure is a more important factor than temperature in cooling process. The result of temperature numerical simulation shows that by increasing pressure, the increasing rate of convection heat transfer coefficient decreases; also, the cooling ability temperature of the vortex tube at low thermal power is tangible. In grinding of soft steel, the minimum quantity lubrication technique with cold air (CAMQL) in comparison with other methods lead to significant reduction of tangential grinding force and friction coefficient, but in general, except in the case of optimum condition which has the highest heat transfer coefficient, surface finish is worse which relate to low heat transfer coefficient of gases at low pressures.

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Numerous models have been proposed to incorporate various equations of state (EOS) into the pseudo potential model. This paper presents an investigation of different EOS types based on the Gong and Cheng model in multiphase-single component flows by the lattice Boltzmann method. Primarily, it is conducted to investigate eight EOS’s classified in four categories; the Shan- Chen EOS, the cubic EOS, the non-cubic EOS, and the cubic and non-cubic combination EOS. The results show that each EOS type results in producing relatively similar spurious currents and has a maximum achievable density ratio. Although by choosing a proper beta parameter for every EOS the simulation errors decrease dramatically, our results show it is impossible to set a constant parameter for the non-cubic EOS. Therefore, a new equation is introduced to predict an efficient beta for the cubic and the Shan- Chen EOS’s. It is also found that the non-cubic, cubic, and non-cubic and cubic combination EOS’s have a wider temperature range and larger density ratios respectively. Hence, we determine a temperature dependent function for the beta parameter prediction instead of using a fixed value for the non-cubic EOS. The results are noticeably in better agreement with those of the Maxwell construction (theoretical results).

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The increasing environmental problems caused by synthetic polymers used in food packaging demonstrate the need for extensive research into the development of biodegradable packaging. The aim of this study was to investigate the effect of adding clay nanoparticles to sodium caseinate biofilm as a factor enhancing its properties. For this purpose, composite films based on caseinat sodium with 0 to 1.5% nanoclay and 0 to 500 ppm Echinophora platyloba essential oil. The effects of nanoclay and essential oil on surface properties, transparency, mechanical properties, water vapor permeability and antioxidant properties were studied. The results showed that the addition of nanoclay has improved the mechanical properties of composites. In this regard, films made of 75 % of nanoclay have the highest tensile strength. The film containing 25% of nanoclay had the highest percentage of elongation at break point. The study of the microstructure of the film shows that the addition of nanoclay reduced the permeability of films to water vapor and also reduced the density of films and Causing their surface to become uneven. The compatibility of Echinophora Platyloba Essential Oil with caseinat sodium also produced satisfactory results in order to produce an active film of bionanocomposite. The film containing 500 ppm of essential oil showed an antioxidant activity of 78%. Overall, , The results showed that nanoclay can have positive effects on the physical properties of sodium caseinate and help to improve its properties.

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