An experimental and numerical study of surface interactions in turbulent swirling jets

Convective heat transfer and drying processes are found in industrial applications from gas turbine blade cooling to drying of food products and paper. In many instances, these processes rely on either a single or an array of fluid jets which impinge onto a surface. Traditionally, non-swirling impinging jets have been used, but interest surrounds possible advantages from imposing swirl into these jets to further promote heat and mass transfer at the surface. The challenge of resolving this question is that including swirl further complicates fluid-surface interactions. Studies are faced with the complexity of flow behaviour, the need for intricate measurement techniques and jets which seamlessly transition from non-swirling to swirling with well-defined boundary conditions. To better understand the nature of turbulent jet impingement with, and without, swirl requires carefully designed experiments covering parameters believed to affect the magnitude and uniformity of heat transfer. This research investigated, experimentally and numerically, incompressible turbulent impinging air jets using aerodynamically derived swirl. The aim was to elucidate the effects of different parameters on fluid flow and surface heat transfer characteristics. Measurements of mean velocity and turbulence, surface pressure and temperatures were done using Constant Temperature Anemometry, integrating micro-manometer (pressure) tappings and steady-state heated thin foil technique via infrared thermography. Imaging for flow visualisations was also done. Numerical simulations were performed using ANSYS Fluent (version 14.5). Test conditions investigated encompassed a range of Reynolds numbers (Re = 11,600 – 35,000), swirl numbers (S = 0 – 1.05) and nozzle-to-plate distances (H = 1D – 6D). Results show that the use of low-to-medium swirl numbers (S = 0.27 – 0.45) is found to improve heat transfer (Nu) in the impingement region compared to non-swirling (S = 0) jets over H ≤ 4D, with little improvement in spatial Nu uniformity. When S further increases, significant enhancement in Nu occurs only at near-field impingement (H ≤ 2D), regardless of the impingement area (footprint). At H ≥ 4D, a significantly low but more uniform radial profile of Nu is obtained. Results conclude the effect of swirl on the heat transfer characteristics is a complex relationship, which depends on the Reynolds number and nozzleto- plate distance. Whilst high swirl can lead to significant improvements in heat transfer, this is not necessarily always the case. It appears that there exist a threshold impingement distance and a transitional swirl number (dependent on Re) over which the effect of swirl on field and turbulence at different swirl numbers and nozzle-to-plate distances, with flow recirculation in near-field impingement (H = 2D) and non-swirl like at far-field (H = 6D). The occurrence of peak heat transfers at different swirl numbers is largely correlated with swirl induced turbulence characteristics near the impingement surface. Increase in Reynolds number augments the magnitude of Cp and heat transfer. For a given S, flow field and heat transfer distributions are found to be largely independent of Re

University Students Perception of Acceptance and Rejection

The purpose of this study was to extend the existing body of knowledge on the perception of acceptance and rejection among the university students A conceptual framework which illustrates three dimensions of acceptance and rejection including parental siblings and peer group was developed The present research was a descriptive study which used an indigenous research inventory to measure acceptance and rejection The study was carried out on a sample of 100 university students and it explored the impact of demographic variables including gender age birth order and family income level on determining the level of acceptance and rejection Result of the study revealed that the phenomenon of university students acceptance and rejection does exist among Male students experience higher parental and siblings rejection than females Students from higher income families experience higher rejection compared to students from low income families The findings also indicated that different demographic variables contribute significantly in determining the perceived level of acceptance and rejectio

Impact of Weather on Household Welfare: Cross Sectional Evidence from Bangladesh

This study aims to determine how Bangladeshi household welfare varies depending on the weather. The Household Income Expenditure Survey (HIES) 2016 data and historical Bangladeshi monthly rainfall data are both used in this study. The log of per capita consumption and the food diversity index serve as measures of the welfare at the household level. The numerous illnesses, such as pneumonia, fever, and diarrhea, are used to gauge an individual's level of welfare. This study discovers that rural households' log per capita consumption grows by more than 3% more than that of other households on average for every unit increase in rainfall. Furthermore, food diversification has benefited from rains. Rainfall generally raises the food diversity index, which raises the diversity of foods. This implies that rainfall on average increases households’ welfare. DOI: 10.7176/JESD/13-18-07 Publication date:September 30th 202

Flexible planar metamaterials with tunable Poisson’s ratios

This research reports on the design, fabrication, and multiscale mechanical characterization of flexible, planar mechanical metamaterials with tailorable mechanical properties. The tunable mechanical behavior of the structures is realized through the introduction of orthogonal perforations with different geometric features. Various configurations of the perforations lead to a wide range of Poisson’s ratios (from −0.8 to 0.4), load-bearing properties, and energy absorption capacities. The correlations between the configuration of the perforations and the auxetic response of the structures are highlighted through computational and experimental characterizations performed at multiple length scales. It is demonstrated that the local in-plane rotation of the solid ligaments in a uniaxially loaded structure is the primary factor that contributes to its strain-dependent auxetic behavior at macroscopic scales. Confinement of these local rotations is then used as a practical strategy to activate a self-strengthening mechanism in the auxetic structures. It is further shown that the fabrication of planar flexible structures with controllable Poisson’s ratios is feasible through spatial adjustment of perforations in the structure. Finally, discussions are provided regarding the practical applications of these structures for a new generation of highly energy-absorbing protective equipment

Flexible planar metamaterials with tunable Poisson\u27s ratios

This research reports on the design, fabrication, and multiscale mechanical characterization of flexible, planar mechanical metamaterials with tailorable mechanical properties. The tunable mechanical behavior of the structures is realized through the introduction of orthogonal perforations with different geometric features. Various configurations of the perforations lead to a wide range of Poisson\u27s ratios (from −0.8 to 0.4), load-bearing properties, and energy absorption capacities. The correlations between the configuration of the perforations and the auxetic response of the structures are highlighted through computational and experimental characterizations performed at multiple length scales. It is demonstrated that the local in-plane rotation of the solid ligaments in a uniaxially loaded structure is the primary factor that contributes to its strain-dependent auxetic behavior at macroscopic scales. Confinement of these local rotations is then used as a practical strategy to activate a self-strengthening mechanism in the auxetic structures. It is further shown that the fabrication of planar flexible structures with controllable Poisson\u27s ratios is feasible through spatial adjustment of perforations in the structure. Finally, discussions are provided regarding the practical applications of these structures for a new generation of highly energy-absorbing protective equipment

Does FDI intensify Economic Growth? Empirics from Bangladesh.

Inward FDI to the middle-income countries has the evidence as a major stimulus to the economic growth; conventionally at export-oriented manufacturing sector. In point of fact, basic macro fundamentals like as growth of gross domestic capital formation, foreign reserve, infrastructure etc. accelerates the FDI inflows. This study reviews the long-run trend on the time scale of FDI to Bangladesh over the period 1975- 2006 and major factors determining foreign companies' decisions to invest, in associated with economic growth. Contents of the paper describe the theoretical development and extensive literature review to find out the appropriate variables to deter the foreign direct investment from time series data. On the basis of intricate link between foreign direct investment and growth, all explained determinants enhance the facilitation, turnover, and return in FDI concentrated sectors that promote long-term sustainable growth with specific shortcomings, directly or indirectly, in our labor-intensive economic activity. Reduced government’s ineffectiveness along with supporting policy framework makes Bangladesh as an attractive destination of FDI, that has a positive spillover and significant impacts affect over time through dynamic effects on economic growth

Does FDI intensify Economic Growth? Empirics from Bangladesh.

Inward FDI to the middle-income countries has the evidence as a major stimulus to the economic growth; conventionally at export-oriented manufacturing sector. In point of fact, basic macro fundamentals like as growth of gross domestic capital formation, foreign reserve, infrastructure etc. accelerates the FDI inflows. This study reviews the long-run trend on the time scale of FDI to Bangladesh over the period 1975- 2006 and major factors determining foreign companies' decisions to invest, in associated with economic growth. Contents of the paper describe the theoretical development and extensive literature review to find out the appropriate variables to deter the foreign direct investment from time series data. On the basis of intricate link between foreign direct investment and growth, all explained determinants enhance the facilitation, turnover, and return in FDI concentrated sectors that promote long-term sustainable growth with specific shortcomings, directly or indirectly, in our labor-intensive economic activity. Reduced government’s ineffectiveness along with supporting policy framework makes Bangladesh as an attractive destination of FDI, that has a positive spillover and significant impacts affect over time through dynamic effects on economic growth

Rational Design of Peptide Ligands Based on Knob−Socket Protein Packing Model Using CD13 as a Prototype Receptor

Structure-based computational peptide design methods have gained significant interest in recent years owing to the availability of structural insights into protein–protein interactions obtained from the crystal structures. The majority of these approaches design new peptide ligands by connecting the crucial amino acid residues from the protein interface and are generally not based on any predicted receptor–ligand interaction. In this work, a peptide design method based on the Knob–Socket model was used to identify the specific ligand residues packed into the receptor interface. This method enables peptide ligands to be designed rationally by predicting amino acid residues that will fit best at the binding site of the receptor protein. In this, specific peptide ligands were designed for the model receptor CD13, overexpression of which has been observed in several cancer types. From the initial library of designed peptides, three potential candidates were selected based on simulated energies in the CD13 binding site using the programs molecular operating environment and AutoDock Vina. In the CD13 enzymatic activity inhibition assay, the three identified peptides exhibited 2.7–7.4 times lower IC50 values (GYPAY, 227 μM; GFPAY, 463 μM; GYPAVYLF, 170 μM) as compared to the known peptide ligand CNGRC (C1–C5) (1260 μM). The apparent binding affinities of the peptides (GYPAY, Ki = 54.0 μM; GFPAY, Ki = 74.3 μM; GYPAVYLF, Ki = 38.8 μM) were 10–20 times higher than that of CNGRC (C1–C5) (Ki = 773 μM). The double reciprocal plots from the steady-state enzyme kinetic assays confirmed the binding of the peptides to the intended active site of CD13. The cell binding and confocal microscopy assays showed that the designed peptides selectively bind to the CD13 on the cell surface. Our study demonstrates the feasibility of a Knob–Socket-based rational design of novel peptide ligands in improving the identification of specific binding versus current more labor-intensive methods

Does FDI intensify Economic Growth? Empirics from Bangladesh.

Inward FDI to the middle-income countries has the evidence as a major stimulus to the economic growth; conventionally at export-oriented manufacturing sector. In point of fact, basic macro fundamentals like as growth of gross domestic capital formation, foreign reserve, infrastructure etc. accelerates the FDI inflows. This study reviews the long-run trend on the time scale of FDI to Bangladesh over the period 1975- 2006 and major factors determining foreign companies' decisions to invest, in associated with economic growth. Contents of the paper describe the theoretical development and extensive literature review to find out the appropriate variables to deter the foreign direct investment from time series data. On the basis of intricate link between foreign direct investment and growth, all explained determinants enhance the facilitation, turnover, and return in FDI concentrated sectors that promote long-term sustainable growth with specific shortcomings, directly or indirectly, in our labor-intensive economic activity. Reduced government’s ineffectiveness along with supporting policy framework makes Bangladesh as an attractive destination of FDI, that has a positive spillover and significant impacts affect over time through dynamic effects on economic growth