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 work examines the ability of a special type of smart antenna array known as Switched Active Switched Parasitic Antenna (SASPA) to produce a directive and electronically steerable radiation pattern. The SASPA array consists of antenna elements that are switchable between active and parasitic states by using P-Intrinsic-N (PIN) diodes. The active element is the element that is supplied by the radio frequency while short-circuiting the terminals of an element in the array results in a parasitic element. Due to the strong mutual coupling between the elements, a directional radiation pattern with high gain and a small beamwidth can be produced with only one active element operating at a time. By changing the parasitic state to the active
... Show MoreThis Research based on an empirical study and tested the hypothesis of transition effects on a sample of young people in Sharjah University and trying to identify a new form of Media which is based on the production of new types of habits and patterns and their cultural impact. Recently, New Media appeared to refer to new types of Communication using the Internet. It’s enormous in the exchange of Information. The new Media contains multiple forms, including the form in which users produce by them to refer the entry of a new area of Media in which exchange of roles between the Sender and the recipient.
This study is trying to identify a new form of Media Web used (Press online or only Press online, Digi
... Show MoreLet R be a commutative ring with unity and let M be a unitary R-module. In this paper we study fully semiprime submodules and fully semiprime modules, where a proper fully invariant R-submodule W of M is called fully semiprime in M if whenever XXïƒW for all fully invariant R-submodule X of M, implies XïƒW. M is called fully semiprime if (0) is a fully semiprime submodule of M. We give basic properties of these concepts. Also we study the relationships between fully semiprime submodules (modules) and other related submodules (modules) respectively.
We introduce in this paper the concept of approximaitly semi-prime submodules of unitary left -module over a commutative ring with identity as a generalization of a prime submodules and semi-prime submodules, also generalization of quasi-prime submodules and approximaitly prime submodules. Various basic properties of an approximaitly semi-prime submodules are discussed, where a proper submodule of an -module is called an approximaitly semi-prime submodule of , if whenever , where , and , implies that . Furthermore the behaviors of approximaitly semi-prime submodule in some classes of modules are studied. On the other hand several characterizations of this concept are
... Show MoreThe Civil Rights era has been an era of struggle for the African American in the
Unites states. Thus, many writers devoted their writing to reflect the racism and
discrimination that many have suffered from, among them is Ralph Ellison.
Ralph Ellison is a 20th century African-American writer and scholar best known for
his renowned, award-winning novel Invisible Man. He illustrates the powerful
social and political forces that conspire to keep black Americans in their place,
denying them the right to life, liberty, and the pursuit of happiness guaranteed to all
Americans. Invisible Man is a 1952 novel that addresses many of the social and intellectual
issues facing African-Americans in the twentieth century. It exa
Deception is defined as a linguistic and non-linguistic behavior that is used in interaction in order to make the addressees believe what is believed to be false or lack evidence. McCornack (1992) classifies deception into four manipulative strategies (i.e., fabrication, distortion, equivocation and concealment), other scholars argue that deception encompasses the strategies of “fabrication (outright lying), equivocation (being vague and ambiguous), or concealment (with holding relevant information) Thus, the present study investigates the deception strategies and motives that are used by Johnny Depp and Amber Heard during their defamation trials. Qualitative and quantitative methods are employed when analyzing the data in question. Th
... Show MoreLanguage ecology is the interactions between the environment and language. Such a discipline, ‘language ecology’ or ‘ecolinguistics has been founded by Einar Haugen’. Accordingly, the study aims at qualitatively reviewing the theoretical and conceptual issues surrounding the subject of language ecology by tracing the roots of language ecology. It further highlights the fundamental inconsistencies between how the concept of ecology is perceived in sociology and biology, and is applied to language, particularly, transposing the main central concepts of bio-ecology, such as relationship/interaction, environment, and organism to human language and theory of ecological-linguistic. The theory wavers among placing the focus
... Show MoreThe most honorable of science was what was related to the book of God, the Almighty, the Constitution of this nation and the way of its guidance and method of advancement there is no life except for him and safety only by its application and it is no secret to the competent studies of the importance of the subjective studies in the Koranic studies to address issues of great importance enlighten the path of the nation and revive From here comes the importance of the topic covered by the research, which is "Intent in the Holy Quran meanings and semantics", and this topic features features that made it worthy of writing, including the importance of clarifying theories of Qur'anic character of a systematic nature, such as the theory of inten
... Show MoreAdopting a policy of attracting investments in all countries, whether developing or developed prevailed, especially after the global crisis, and this trend is imposed by considerations of political and development (urban, economic, and social) can be formulated as a rational policy to solve many problems related to patterns of urban growth, economic, social, and including the problem of housing. As the reality of the housing sector in Iraq will require the allocation of substantial resources to promote it by the research problem is the lack of financial resources and the inability of investments to meet the various requirements including the requirements of economic sectors, particularly in the field of housing, infrastructure an
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