195 research outputs found

    Numerical experiments on the aerodynamics of waveriders

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    Because of a high level of activity in manned space missions and hypersonic transport the ideas on waveriders are currently of great interest. Waveriders have been regarded as the best shapes for space planes. This derives from their high lift capability which will enable the vehicle to slow down at high altitude thus helping it alleviate the kinetic heating problem. The present study reports on the advantages of waveriders for their application to space plane shapes. The advantages of selecting waveriders as lifting shapes is attributed to their flow simplicity by using shapes defined inversely from a two dimensional flow as a basis of their construction. For these deceptively simple shapes initial estimates of the aerodynamic properties can be made through inviscid flow calculations. A historical preview of waveriders suggests that viscous effects are very important for accurate prediction of flowfield around these shapes. However, these effects were not included in the course of development of these shapes. In this study along with the classical theory of waveriders viscosity effects on the waverider design are highlighted. Also emphasised are the important relevant factors in hypersonic flow and the advantages of applying computational fluid dynamics (CFD) for simulation of the flowfield as compared to analytic and experimentation method. In the past, work has been reported on the inclusion of viscous effects by using the boundary layer for the viscous correction. The present study shows that, in the presence of strong viscous-inviscid interaction, viscous effects from these applications can only be reliably predicted using solutions of the Navier-Stokes equations. Based on this strategy numerical solutions of the Navier-Stokes Equations were applied to different waverider shapes to highlight the importance of viscous effects. Since the flow on typical waverider shapes is near conical, then a locally conical approximation was used for two reasons: it simplifies the problem from a 3-D to a 2-D one without compromising significantly accuracy ; it reduces the requirement of computing resources in terms of processor time and storage. Application of the Navier Stokes equations in locally conical form (LCNS) to simulate the flow around idealised waverider shapes revealed interesting off-design flow behaviour for on-design flow conditions. Sensitive effects on performance due to off-design behaviour are observed for caret wings. Results are obtained for 4 cases of caret wings optimised for free stream Mach numbers of 1.44, 1.74, 2.51 and 4.93 and 3 cases of a cone-wing configuration at Mach 10 with angles of attack of 5°, 10° and 15°. For caret wings results show how viscous effects have significant influence even at low Mach numbers. Flow simulation of these cases illustrates the advantage of using CFD on these shapes and shows how incorporating the NS equations provides a powerful tool to explore in detail waverider aerodynamics in on-design and off-design operation. Results also show how suitably it can deal with shock-shock, shock-boundary layer and shock vortex interactions, simultaneously. Also predicted was the effect on heat transfer due to the change in angle of attack of the shape. As caret wing and wing-cone combinations are thought to have limited applicability for practical aircraft shape the studies were extended to more general shapes. This study is the first to deal simultaneously with general shapes derived from both conical and wedge flowfields. General conical-derived shapes were constructed through a numerical approach based on flow around a cone using the Taylor Maccoll theory. For a general wedge-derived shape the base flow was the flow behind wedge induced oblique shock waves. Comparisons were made to evaluate the advantages and disadvantages of each type of configuration generated. Results were discussed in the light of numerical prediction and experimental results published in the literature. It was recognized that if volume constraints are relaxed, then, there are some considerable advantages in using wedge flow as a basis, instead of conical flow. Also it was shown that a change in only the leading edge shape can considerably improve the performance characteristics of waveriders. Furthermore a wedge-derived waverider provides a higher lift than an equivalent cone-derived one and also at off-design conditions a wedge-derived shape shows less sensitivity than its conical counterpart

    Understanding E-Learning Adoption in Pakistan: A TAM-based Analysis of Student Perceptions

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    This research delves into the determinants shaping the adoption and acceptance of e-learning platforms among Pakistani students, employing the Technology Acceptance Model (TAM) as its foundational theoretical framework. The primary objective is to elucidate the intricate interrelationships among performance expectancy (PE), effort expectancy (EE), perceived usefulness (PU), perceived ease of use (PEOU), and behavioural intention (BI) in the context of e-learning technology utilization. Adopting a quantitative research methodology, this study surveys Pakistani e-learning users to systematically analyze the interplay between these pivotal constructs. The resultant findings offer substantial implications for educators, instructional designers, policymakers, and educational institutions, providing critical insights that can inform the strategic design, implementation, and enhancement of e-learning technologies. Ultimately, this research aims to contribute to the development of a more efficacious and inclusive e-learning environment for Pakistani students

    What Are Your Children Watching? Teacher’s Evaluation of the Educational, Emotional, Behavioral, Psychological, Physical & Religious impacts of Cartoons on the School going Children

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    Cartoons in the era of digital media are among the most prevalent medium of entertainment for the children, parents also encourage them to view such contents to engage the children which make an area need to be explained exhaustively by adopting new approaches. There are lot of studies in the past conducted to explain the impacts of the cartoons on the children however, it is remarkable fact that there is lack of the studies in the literature which directly address the observation about the above mentioned impacts in view of the teacher’s. This study deals with the educational, emotional, behavioral and Religious etc. impacts of cartoons on kids in view of teachers of the primary schools as they are considered as the one who can observer these impacts in a profound way. of the of Multan. Different areas of impacts have been analyzed in this study by using survey technique and analysis is conducted and presented in the teacher’s views in this study to examine what they feel that how cartoons are effecting the personalities of the children. Keywords: Educational impacts, Emotional Impacts, Behavioral Impacts, Psychological Impacts, Physical Impacts, Religious Impacts

    RADIOLOGICAL AND PATHOLOGICAL CORRELATION OF LUNG NODULES IN A BACKGROUND OF METASTATIC DISEASE

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    Background: Computed tomography (CT) imaging has improved the chances of detecting small indeterminate (<1 cm) lung nodules. The determination of the underlying malignant or benign nature of a lung nodule poses a great diagnostic challenge and depends on a number of factors, including the radiographic appearance of nodule, the presence of non-pulmonary metastases, characteristics of growth and histological criteria. Methods: The medical records of 89 patients admitted to our specialist cancer centre between 2008 and 2013 were reviewed. Patients of all age groups and tumour category were included in the study. Clinical data of these patients were collected and the following parameters were analysed: Radiographic diagnosis, location, size, laterality and number of nodules and histological impression. The radiological findings were then correlated with histopathological findings. The nodules were sub-classified into groups on the basis of size (A = 0–0.5 cm; B = 0.5–0.9 cm; C = 1.0–1.5 cm and D = >1.5 cm). Results: CT scan reports of 89 patients with lung nodules were reviewed. On radiology, 73/89 (82%) were reported to be malignant nodule. Histopathological review of the biopsies of these 89 nodules confirmed malignancy in 50/89 (56.2%) patients. CT scan was found to be highly sensitive (94%, 95% confidence interval [CI]: 83.43–98.68%) but with a very low specificity (33.3%, 95% CI: 19.10–50.22%). CT scan was found to have a higher negative predictive value (81.2%, 95% CI: 54.34–95.73%) and a lower positive predictive value 64.4% (95% CI: 52.31–75.25%) when correlated with histopathological findings. Pathology of these nodules included metastatic sarcoma (27/89; 30.3%) and carcinoma (18/89; 20.2%). The frequency of the biopsy-proven malignant nodules on the right side was 26/45 (57.8%) and on the left side was 24/44 (54.5%) (P = 0.832). Malignant nodules were more frequent in lower lobes (28/43, 65.1%) than in upper lobes (14/32, 43.8%). These two sites combined accounted for 84% of all malignant nodules. There was a significant correlation between nodule size and likelihood of underlying malignancy. The overall prevalence of malignancy in the larger nodules (C and D) was much higher (23/30 and 76.7%) compared to the smaller sized (A and B) nodules (27/58 and 46.8%), P < 0.05.Conclusion: CT scan is a useful tool in the initial clinical assessment of indeterminate lung nodules with high sensitivity (94%) and a high negative predictive value (81.2%).Key words: Computed tomography, fibrosis, indeterminate lung nodule, infection, lung nodule, malignancy, metastase

    Effect of Human Resource Planning on Organizational Performance of Telecom Sector

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    Human resource planning is one of the growing areas of academic research. Organizations regard its human resource as their core competency because it would lead towards better organizational performance. This research focuses on effect of human resource planning on the organizational performance. Objective of this research is to determine key determinants of formal human resource planning that contributes towards performance in the telecom sector. The data collected from top managers, middle level managers and the first line HR managers of 50 offices including head offices and regional offices of 160 questionnaires including some interview and open ended questions based on the measures of performance and Human Resource Planning. The results from the factor analysis on HRP measures selection, training, and incentives and the organizational performance measures which are job satisfaction, efficiency, employee motivation and technology constitutes significant and a positive relationship with other. As modern HR practices are implemented in telecom sector and companies would spend more on Human Resources, it would lead towards High performance achievement. Keywords – Human Resource Planning, Telecom Sector, Organizational Performance, Selection, Training and Incentives Paper Type­– Research Pape

    Motivation of Employees towards the Adaptation of Technology

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    Technological change has become the mode of operation in the 20th century business community. As the workplace product transforms from paper to information services, employers and employees scramble to keep abreast of the rising tide of information and the new service opportunities created by the innovations in technology available to business. Employees are naturally expected to adapt to the ever changing norms of technology. New technological changes face employees in the workplace every day. Some employees embrace the changes that technology brings. They seek new applications for the innovations, while others resist and become defensive. Is the defensive behavior of some, a symptom of a sociological system controlling the individual? Does cognitive ability govern individual attitudes toward technological innovations? Does race, age or gender play a role in one’s perception of incorporation of new technology in the workplace? Is an individual’s attitude predetermined by past experiences? This research is the summary of a review of the literature around the above questions and a try to explore the aspect or factors that really affect the attitude of a person to adopt new technology at work place. The objective is to identify the contributing influences of an individual’s attitude towards a technological innovation in the workplace. Keywords: Employees, Motivation, Information Technology, Training, Success

    Topical nanoemulsion of turmeric oil for psoriasis: characterization, ex vivo and in vivo assessment

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    Psoriasis is a chronic; T lymphocyte mediated autoimmune inflammatory disorder characterized by well-defined erythematous (reddish) plaques with large adherent silvery scales that affects the skin and other parts of the body. The essential oil in turmeric is anti-inflammatory and effective in treating chronic disorders like psoriasis that have inflammation as a root symptom. Nanoemulsions are isotropic, thermodynamically stable transparent (or translucent) systems of oil, water, surfactant and co-surfactant with a droplet size usually in the range of 20–200 nm. Their long-term stability and ease of preparation (spontaneous emulsification) make it promising tool for drug delivery. The aim of this study was to obtain nanoemulsions of turmeric oil for psoriasis and to evaluate their physical stability, irritation potential and in vivo inflammatory activity. For the preparation of nanoemulsion titration method was used which was composed of 15% turmeric oil, 42 % Smix (1:1) and 43 % distilled water. The nanoemulsion was stable during the period of study and was found to be practically non-irritating in the organotypic HET-CAM model. The anti inflammatory activity of optimized nonoemulsion was carried out by carragennen induced paw edema and found to be 70.35 % inhibition

    Fuzzy Logic Speed Regulator for D.C. Motor Tuning

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    A D.C. motor's rotational speed is regulated in this study using a PID controller and a fuzzy logic controller. In contrast to the fuzzy logic controller, which uses rules based on knowledge and experience, the proportional-integral-derivative (PID) controller requires a mathematical system model.   This study investigates the regulation of a DC motor's velocity using PID and fuzzy logic controllers. The PID controller utilizes a mathematical model and parameter tuning by trial and error. Still, the fuzzy logic controller (FLC) operates on rule-based knowledge, enabling it to handle the nonlinear features of the DC motor effectively. The FLC design entails intricate determinations, including the establishment of a rule base and the process of fuzzification. A total of 49 fuzzy rules have been devised to achieve precise control. Based on MATLAB/SIMULINK simulations, the study concludes that the Fuzzy Logic Controller (FLC) beats the Proportional-Integral-Derivative (PID) controller. The FLC exhibits superior transient and steady-state responses, shorter response times, reduced steady-state errors, and higher precision. This study emphasizes the efficacy of the FLC (Fuzzy Logic Controller) in dealing with the difficulties associated with DC motor control. It presents a strong argument for the suitability and efficiency of FLCs in industrial environments compared to conventional PID (Proportional-Integral-Derivative) controllers. There are a wide variety of ways to construct a fuzzy logic controller. The speed error and the rate of change in the speed error are two inputs to the FLC. Defuzzification is done by focusing on the core of the problem. The results show that FLC is superior to PID controllers in efficiency and effectiveness due to its reduced transient and steady-state factors
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