Investigation of heat transfer phenomena and flow behavior around electronic chip

Computational study of three-dimensional laminar and turbulent flows around electronic chip (heat source) located on a printed circuit board are presented. Computational field involves the solution of elliptic partial differential equations for conservation of mass, momentum, energy, turbulent energy, and its dissipation rate in finite volume form. The k-ε turbulent model was used with the wall function concept near the walls to treat of turbulence effects. The SIMPLE algorithm was selected in this work. The chip is cooled by an external flow of air. The goals of this investigation are to investigate the heat transfer phenomena of electronic chip located in enclosure and how we arrive to optimum level for cooling of this chip. These parameters, which will help enhance thermal performance of electronic chip and flow patterns, through the understanding of different factors on flow patterns. The results show the relation between the temperature rise, heat transfer parameters (Nu, Ra) with (Ar, Q) for two cases of laminar and turbulent flows

Investigation Of Heat Transfer Phenomena And Natural Flow Behavior Around A Heated Square Cylinder Placed In A Cooled Elliptical Enclosure

In this paper, a numerical study of the effect of a hot square cylinder placed on acooled elliptical enclosure of a laminar natural convection was carried out. This problemis solved by using the partial differential equations, which are the stream vorticityformulation for the flow and heat transfer in curvilinear coordinates. An ellipticalfunction is used, which makes the coordinate transformation from the physical domainto the computational domain be set up by an analytical expression. About 48 tests areperformed for different ratios of the geometry such as, a /b =1.5,2.,3 , l /b = 0.25,0.5 ,and Rayleigh number from 103 to 106, for two position of the major axis of the ellipticalenclosure, horizontal (HEE) and vertical (VEE). The results obtained in the form ofvelocity vectors, streamlines, isotherms, and Nusselt number. The results show that, theincrease of the major axis of the enclosure ( a /b ratio) leads to increase the averageNusselt number and decrease the flow strength for all Rayleigh numbers. Moreover, forRa≤104, there are a little difference in the results of ave Nu for all a / b and l / b ratios,but if Ra increases, the change in the results is clear and large

Rol de brasinoesteroides y etapas de pulverizacion en plantas de Zea mays

Introduction: A Field experiment was conducted at the experimental farm, Dept. of Field Crop (Al-Jadriya), Coll. of Agric., Univ. of Baghdad to study the effects of brassinolide concentrations and spraying stages on yield and its components of maize (Baghdad 3 cultivar) during spring and autumn seasons in 2017. Materials and Methods: A randomized complete blocks design arranged in actorial experiment was used with three replicates. The first factor included three concentrations (0, 2 and 4 mg L-1) of brassinolide,and the second factor included spraying stages (4, 8, 12, 4 + 8, 4 + 12, and 8 + 12 leaves) using the same concentrations for each stage. Results and discussion: Results showed that the concentration 4 mg L-1 gave the highest grain yield (6.59 and 7.15 t ha-1) for its superiority in 500 grain weight (102.74 and 112.26 g) and number of ears per plant (1.43 and 1.44 ear) for both spring and autumn seasons, respectively. The spraying stage (4 + 8 leaves) recorded highest grain yield (6.33 and 6.77 t ha-1), and 500 grain weight (104.73 and 119.20 g) for both spring and autumn seasons, respectively. The effect of interaction for both factors was significant in most studied traits. Conclusion: Therefore, we recommend spraying Brassinolide in a concentration of 4 mg L-1 at the stage 4 + 8 leaves to increase grain yield of maiz

Synthesis,Characterization,Thermal and Kinetic Photo Chemical Decomposition Study of New Azo Dye 7-[2-(BenzImidazolyl)Azo]-8-Hydroxy Quinoline and its Znic (II) Complex

This research includes preparation and spectral identification of a new azo ligand7-[2-(Benzimidazolyl) azo]-8-Hydroxy quinoline (BIAHQ) by using UV-Vis,  IR, 1H-NMR and mass spectra.The preparation of Zn(II)-complex of this ligand and identification by UV-Vis, IR radation spectrum,which characterized by elemental analysis.The analytical data shows that the metal to ligand ratio [M:L] of Zn(II)complex is 1:2.Decomposition kinetics was studied photochemical complex through irradiation solution complex single wavelength light ?=365 nm ,at temperature of 25 ?C for 60 minutes  and ethanol solvent was found to be the reaction from first order. Also,the calculated rate concetant photolysis kd mediated follow spectral changes during the process of irradiation . In order to reach the optimal conditions for the dissolution of the complex, it has been studied the impact of several factors on photochemical reaction of disintegration of the complex which include : Study the effects of the change in the intensity of light. More over  disintegration of the complex has been studied in temperature range 15-30?C, and studied the effects of the acidic function within range 3-9.The effects of several alcoholic solvents were studied on the rate of disintegration and these solvents are methanol, ethanol, isopropanol and1-butanol.Free ligand and Zn(II)complex were submitted to thermal analysis(TGA and DSC) activation thermodynamic data are calculated

Optimal scales to observe habitat dynamics: A coral reef example

A new technique to estimate the characteristic length scales (CLSs) of real ecological systems provides an objective means to identify the optimal scale(s) of observation to best detect underlying dynamical trends. Application of the technique to natural systems has focused on identifying appropriate scales to measure the dynamics of species as descriptors of community and ecosystem dynamics. However, ecosystem monitoring is often based not on assessing single species, but on species assemblages, functional groups, or habitat types. We asked whether the concept of CLSs based on dynamic interactions among species could be extended to examine interactions among habitat types and thus to identify optimal scales for observing habitat dynamics. A time series of three spatial maps of benthic habitats on a Caribbean coral reef was constructed from aerial photographs, Compact Airborne Spectrographic Imager (CASI) images, and IKONOS satellite images, providing the short time sequence required for this technique. We estimated the CLS based on the dynamics of three distinct habitat types: dense stands of seagrass, sparse stands of seagrass, and Montastrea patch reefs. Despite notable differences in the areal extent of and relative change in these habitats over the 21-year observation period, analyses based on each habitat type indicated a similar CLS of similar to 300 m. We interpret the consistency of CLSs among habitats to indicate that the dynamics of the three habitat types are linked. The results are encouraging, and they indicate that CLS techniques can be used to identify the appropriate scale at which to monitor ecosystem trends on the basis of the dynamics of only one of a disparate suite of habitat types

Sardines of the Gulf of Mannar ecosystem - fishery and resource characteristics of major species

Fishery, species diversity and resource characteristics of exploited sardine resources of the genera Sardinella were studied during 2000-2008. Sardines were exploited by sardine gillnets, trawls and shore seine. Annual average production for the period was 20,249 t. They formed about one fourth of the total marine fish production (77,443 t) of the region. Fishery was supported by eight species dominated by Sardinella gibbosa, followed by S. sirm, S. albella and S. longiceps. Fishery fluctuated widely with declining trend over the years mainly due to reduction in the fishing effort following destruction of traditional crafts and gears during the Tsunami in 2004. Oilsardine in the fishery registered an increasing trend with wide annual fluctuation during the period. Stock assessment studies show that the exploitation rate of major species ranged between 0.45 and 0.62, against the EMSY value of 0.72 and 0.86. This indicated that sardine resource as a whole is under-exploited, offering considerable scope for enhancing their yield. Despite contributing a higher share to marine fish production, sardines, along with other small pelagics, play a vital ecological role in sustaining the stock and fishery of other predatory groups especially large pelagics by providing them a major share of their forage. They support 46 to 87% of the total food of pelagic predators and 14 to 29% of demersal predators

MIXED CONVECTION FROM ELECTRONIC EQUIPMENT COMPONENT AT DIFFERENT POSITION AN ENCLOUSER BY PRIMITIVE VARABILS METHOD

A numerical study of mixed convtion cooling of heat dissipating electronic component, located in a rectangular enclosure, and cooled by an external through flow of air is carried out.A conjugate problem is solved by primitive variables method, describing the flow and thermal fields in air .The interaction between the components is of interest here, depending on their relative placement in the enclosure, and different configuration are considered. for Re=100 laminar, steady flow is predicted for up to Gr/Re2 =25 according to heat source location in the enclosure. The mixed convection regime, where the buoyancy effects are comparable to the forced flow, occurs at values of Gr/Re2 between 0.01 and 25 .The results are of values in search for suitable placement of electronic components in an enclosed region for an effective heat removal. In general, it appears that the location of the source on the left vertical wall is the most favorable in terms of cooling. Laminar results are predicted up for up to Gr = 2.5*105 for all configurations studie

Breast Cancer in Thi-Qar 2018, it's determinants, histopathological presentation and six years' time trends, A comparative study

Objectives : to assess  the soscio-demographic characteristics,  clinico-pathological presentations, and important determinant of breast cancer patients  counseling breast disease center in Thi-Qar 2018, to study and compare  the yearly time trend of breast cancer in Thi-Qar from 2013-2017. Methods: A cross sectional analytical design was used. all women presented with breast mass at defined age, at the time of study, were included. Results: About  (59.5%)of malignant masses were moderately differentiated and (32%) of them were poorly differentiated (8.5%) were well differentiated at the time of study, Also about half of patients presents at late stages, while only 10% at early stages , in other word. The age was strongly correlated factor and about 57.5% of the malignancies were above 45. Recommendations :  1.Further studies with different design permit longer duration, are required  and preferred to be follow-up type to determine the effect of confound risk factors as age, stress and radiation rather than defined ones, also studies required about response to therapy and follow the complication.  2.Regular programmed screening required to detect the cancer in the earlier stage, and facilitate the availability of screening tools at the health care centers and in  peripheries hospitals of Thi-Qar

An adaptive wavelet transformation filtering algorithm for improving road anomaly detection and characterization in vehicular technology

Accelerometers are widely used in modern vehicular technologies to automatically detect and characterize road anomalies such as potholes and bumps. However, measurements from an accelerometer are usually plagued by high noise levels, which typically increase the false alarm and misdetection rates of an anomaly detection system. To address this problem, we have developed in this paper an adaptive threshold estimation technique to filter accelerometer measurements effectively to improve road anomaly detection and characterization in vehicular technologies. Our algorithm decomposes the output signal of an accelerometer into multiple scales using wavelet transformation (WT). Then, it correlates the wavelet coefficients across adjacent scales and classifies them using a newly proposed adaptive threshold technique. Furthermore, our algorithm uses a spatial filter to smoothen further the correlated coefficients before using these coefficients to detect road anomalies. Our algorithm then characterizes the detected road anomalies using two unique features obtained from the filtered wavelet coefficients to differentiate potholes from bumps. The findings from several comparative tests suggest that our algorithm successfully detects and characterizes road anomalies with high levels of accuracy, precision and low false alarm rates as compared to other known methods