A pioneering idea for increasing the thermal performance of heat transfer fluids was to use ultrafine solid particles suspended in the base fluid. Nanofluids, synthesized by mixing solid nanometer sized particles at low concentrations with the base fluid, were used as a new heat transfer fluid and developed a remarkable effect on the thermophysical properties and heat transfer coefficient. For any nanofluid to be usable in heat transfer applications, the main concern is its long-term stability. The aim of this research is to investigate the effect of using four different surfactants (sodium dodecyl benzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), cetyl trimethylammonium bromide (CTAB), and gum Arabic (GA)), each with three different concentrations, and five ultrasonication times (15, 30, 60, 90, and 120 min) on the stability of water-based graphene nanoplatelets (GNPs) nanofluids. In addition, the viscosity and thermal conductivity of the highest stability samples were measured at different temperatures. For this aim, nineteen different nanofluids with 0.1 wt% concentration of GNPs were prepared via the two-step method. An ultrasonication probe was utilized to disperse the GNPs in distilled water. UV–vis spectrometry, zeta potential, average particle size, and Transmission Electron Microscopy (TEM) were helpful in evaluating the stability and characterizing the prepared nanofluids. TEM and zeta potential results were in agreement with the UV–vis measurements. The highest nanofluid stability was obtained at 60-min ultrasonication time. The prepared water-based pristine GNPs nanofluids were not stable, and the stability was improved with the addition of surfactants. The presence of SDBS, SDS, and CTAB surfactants in the nanofluids resulted in excessive foam. The best water-based GNPs nanofluid was selected in terms of better stability, higher thermal conductivity, and lower viscosity. From all the samples that were prepared in this research, the (1–1) SDBS–GNPs sample with 60-min ultrasonication showed the highest stability (82% relative concentration after 60 days), the second better enhancement in the thermal conductivity of the base fluid (8.36%), and nearly the lowest viscosity (7.4% higher than distilled water).
This paper aims to evaluate the reliability analysis for steel beam which represented by the probability of Failure and reliability index. Monte Carlo Simulation Method (MCSM) and First Order Reliability Method (FORM) will be used to achieve this issue. These methods need two samples for each behavior that want to study; the first sample for resistance (carrying capacity R), and second for load effect (Q) which are parameters for a limit state function. Monte Carlo method has been adopted to generate these samples dependent on the randomness and uncertainties in variables. The variables that consider are beam cross-section dimensions, material property, beam length, yield stress, and applied loads. Matlab software has be
... Show MoreAW Ali T, Journal of the Faculty of Medicine, 2016 - Cited by 1
In this paper, An application of non-additive measures for re-evaluating the degree of importance of some student failure reasons has been discussed. We apply non-additive fuzzy integral model (Sugeno, Shilkret and Choquet) integrals for some expected factors which effect student examination performance for different students' cases.
The non-isothermal crystallization kinetics and crystalline properties of nanocomposites poly butyleneterephthalate, [PBT] /multiwalled-carbon nanotubes (MWCNTs) were tested by differential scanning calorimetry (DSC). PBT/(MWCNTs) nanocomposite was prepared by ultrasonicated of MWCNTs (0.5, 1, 2, 4 wt %) in dichloromethane (DCM) and after that the powdered PBT polymer was added to the MWCNTs solution. The non-isothermal crystallization results show that increasing the MWCNTs contents, decreased the melting temperature (Tm) of PBT/(MWCNTs) nanocomposite as compared with pure PBT, while resulting in improving the degree of crystallinity. These results indicated that a little amount of MWCNTs can be evident strong nucleating agent in PBT na
... Show MoreThe main aim of this study is to assess the performance and residual strength of post-fire non-prismatic reinforced concrete beams (NPRC) with and without openings. To do this, nine beams were cast and divided into three major groupings. These groups were classified based on the degrees of heating exposure temperature chosen (ambient, 400, and 700°C), with each group containing three non-prismatic beams (solid, 8 trapezoidal openings, and 8 circular openings). Experimentally, given the same beam geometry, increasing burning temperature caused degradation in NPRC beams, which was reflected in increased mid-span deflection throughout the fire exposure period and also residual deflectio
The Islamic religion is a religion of tolerance and is pleased with worship and other legislation and the idea of peace is an authentic and profound idea related to the call for coexistence with all religions. The Prophet (PBUH) was keen to organize his relations with non-Muslims on the basis of cohabitation, On the basis of love and intolerance, God Almighty says: "If your Lord wants to make people one nation and they are still backward." Surah Hud: 118 Islam has taken care of the people and made them tolerant brothers who sympathize with their different beliefs. Which means that everyone has the right to live, believe and believe what he sees right and have the freedom to perform the acts of worship and beliefs he deems correct. The di
... Show MoreBackground: The desire for an attractive appearing fixed orthodontic appliance fueled the use of ceramic brackets and clear accessories. Elastics are one of the most versatile materials available to orthodontists so studying their effect on the esthetic appearance is important. This an in vivo study, conducted to evaluate the effect of exposing stretched clear elastomeric ligatures to the oral environment from four different companies (OrthoTechnology, Morelli, Ortho Organizer, and Ormco). Materials and Methods: A total of 240 elastomeric modules were examined, 60 modules from each brand. Each of the 60 patients enrolled in the study, received 4 elastomeric modules on the 4 lower incisors, one from each brand. The specimens were placed on t
... Show MoreFrom a group of 60 patients with dentoalveolar infections among which 10 were diabetic and 10 non-diabetic were elected as test group as well as 10 normal subjects as control group. Six Staphylococcus aureus and Streptococcus anginousus were diagnosed in the first and second group of the patients the immune status of the patients and control subject were tested by pathogen specific antibody titre, neotrophil NBT reduction phagocytosis and leukocyte inhibition LIF. Diabetic patients with dentoalveolar infection shows decreased specific antibody titers, subnormal neutrophil NBT phagocytic % as well as non significant LIF % in comparison non diabetic reveal high specific antibody titers against , high neutrophil NBT% and significant LIF% re
... Show Moreيعد التقطيع الصوري من الاهداف الرئيسة والضرورية في المعالجات الصورية للصور الرقمية، فهو يسعى الى تجزئة الصور المدروسة الى مناطق متعددة اكثر نفعاً تلخص فيها المناطق ذات الافادة لصور الاقمار الصناعية، وهي صور متعددة الاطياف ومجهزة من الاقمار الصناعية باستخدام مبدأ الاستشعار عن بعد والذي اصبح من المفاهيم المهمة التي تُعتمد تطبيقاته في اغلب ضروريات الحياة اليومية، وخاصة بعد التطورات المتسارعة التي شهد
... Show MoreMany of the key stream generators which are used in practice are LFSR-based in the sense that they produce the key stream according to a rule y = C(L(x)), where L(x) denotes an internal linear bit stream, produced by small number of parallel linear feedback shift registers (LFSRs), and C denotes some nonlinear compression function. In this paper we combine between the output sequences from the linear feedback shift registers with the sequences out from non linear key generator to get the final very strong key sequence