A numerical study of the double-diffusive laminar natural convection in a right triangular solar collector has been investigated in present work. The base (absorber) and glass cover of the collector are isothermal and isoconcentration surfaces, while the vertical wall is considered adiabatic and impermeable. Both aiding and opposing buoyancy forces have been studied. Governing equations in vorticity-stream function form are discretized via finite-difference method and are solved numerically by iterative successive under relaxation (SUR) technique. Computer code for MATLAB software has been developed and written to solve mathematical model. Results in the form of streamlines, isotherms, isoconcentration, average Nusselt, and average Sherwood number, are presented for wide range of the buoyancy ratio , angle of inclined glass cover with horizontal coordinate , Lewis number , thermal Rayleigh number , and Prandtl number . The results show that above parameters have strong influences on the patterns of streamline, isotherms, isoconcentration, average Nusselt number and average Sherwood number. Results show that a decrease in the angle of inclined glass cover with horizontal coordinate ( leads to increase average Nusselt number and average Sherwood number. For (N > 0), both average Nusselt number and average Sherwood number increase with increasing of buoyancy ratio and Rayleigh number. By contrast for ( these values decreases. Also, increasing of the buoyancy ratio for positive (N > 0), at the same Rayleigh number enhance the heat and mass transfer rate. A comparison is made with the previous numerical results and it found to be reveal a good agreement.
Cleaning is one of the services provided by the state and its ad hoc institutions. Every developed country is clean due to the good planning and attention given to the staff of all municipalities and service institutions. Beside, the attention paid to this sector is considered one of the windows to maintain the states’ aesthetics. If janirtos stop disposing of all the discarded wastes, the result will be having big piles of waste, affecting accordingly the health and safety of its citizens and the aesthetics of the areas. The janitors and those responsible for them are tha staff that the state must take care of because of their importance to the state in general and to the province in particular. The importance of the research
... Show MoreTo reduce solar radiation transmittance into buildings through windows facing east or west during summer, a window inclination from vertical position is suggested. The inclination of the window glazing and the rate of unwanted solar radiation during summer can be calculated knowing the dialy inclination of the sun rays. The inclination of window glazing depends on the latitude of the position required. For instance in Baghdad which is at about 33o north latitude a slope of 15o for window glazing is sufficient to prevent about 419 MJ/m2 of total solar radiation energy from penetration during summer for clear glazing of window facing east. This value drops to about 96 MJ/m2 during winter. Therefore the ratio between the energy saved for co
... Show MoreWriting plays an effective role in developing one's thinking and
enhancing Learning. It is, in fact, a means of widening one's own views about
the world for the numerous uses that it can serve (Samuel, 1988:28).
In regard to the unquestionable significance of writing in the teaching –
Learning process, the traditional approach seems to be far from being able to
put such significance into practice. Traditionalists give priority to formulating
students' ideas before using prescribed rhetorical framework and then
submitting the written product for grading. Emphasis is, therefore, limited to the
prewriting stage where a certain topic is explored, and the role of the teacher is
confined to assigning the topic and
Mycobacterium tuberculosis resistance to rifampicin is mainly mediated through mutations in the rpoB gene. The effects of rpoB mutations are relieved by secondary mutations in rpoA or rpoC genes. This study aims to identify mutations in rpoB, rpoA, and rpoC genes of Mycobacterium tuberculosis isolates and clarify their contribution to rifampicin resistance. Seventy isolates were identified by acid-fast bacilli smear, Genexpert assay, and growth on Lowenstein Jensen medium. Drug susceptibility, testing was performed by the proportional method. DNA extraction, PCR, and sequencing were accomplished for the entire rpoA, rpoB, and
... Show MoreThe present study has three objectives: 1) to investigate the prevalence of complex nominals in economic discourse represented via the selected business news texts, 2) to shed some light on the most common translation errors made by second year students in the Department of Translation in rendering complex nominals into Arabic, and 3) to detect the possible causes behind such translation errors and suggest some translation tips which might sound helpful to the students of translation to find the most suitable translation equivalent. The present study is based on an empirical survey in which a selective analysis of someeconomic texts represented in business news texts is made. A corpus of 159 complex nominals was selected from seven busin
... Show MoreThe enhancement of ZnSe/Si Heterojunction by adding some elements (V, In and Cu) as impurities is the main goal because they contribute to the manufacturing of renewable energy equipment, such as solar cells. This paper describes the preparation of thin films ZnSe with V, In and Cu doped using thermal evaporation method with a vacuum of 10–5 Torr. The thin film was obtained from this work could be applied in heterojunction solar cell because of several advantages including high absorption coefficient value and direct band gap. The samples prepared on a glass and n-type Si wafer substrate. These films have been annealed for 1 h in 450 K. X-ray diffraction XRD results indicated that ZnSe thin film possesses poly-crystalline structure after
... Show MoreAbstract:
Today, the financial and banking sector is witnessing a qualitative shift thanks to financial technology services, which provide their services to many individuals and companies in quick, easy and less expensive ways compared to traditional means. Financial technology is a new form of financial science that combines financial transactions and technological skills concerned with providing financial services and improving the work environment within Banking institutions, and financial technology provides many advantages such as lower transaction costs, instant payment, and saving more time and effort in conducting banking
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