Acoustical Exploitation of Rough, Mixed Impedance and Porous Surfaces Outdoors

This thesis is a contribution towards developing cost-effective ways for reducing outdoor traffic noise in outdoor environments by exploiting the interaction between sound travelling directly to a listener from the source and sound reflected by the intervening ground. Sound propagation over different kinds of porous, rough and mixed impedance ground surfaces have been studied experimentally and numerically. Measurements of short-range acoustic level difference spectra over outdoor ground surfaces and artificially-created surfaces outdoors and in the laboratory have been compared with predictions to establish suitable impedance models. Sound propagation over mixed impedance ground having single or multiple impedance discontinuities has also been studied. Acoustic transmission loss through vegetation, crops and hedges has been investigated. The phenomenon of sound diffraction and periodicity due to rough periodic ground surfaces has been explored through artificially created rough surfaces in the laboratory and outdoors. The phenomenon of surface wave propagation over rough hard surfaces and porous surfaces has been explored through laboratory experiments. Measured data indoors and outdoors have been used to validate numerical (BEM and FEM), empirical and analytical (MST) prediction techniques. The validated numerical methods have been used to make predictions at scales suitable for attenuating traffic noise by means of carefully designed ground treatments. The work has also been extended to railway and tramway noise. It has been found that replacing hard ground with porous ground, introducing single or multiple impedance discontinuities, growing vegetation and introducing low height roughness can all contribute between 3 and 15 dB additional attenuation of traffic noise. In respect of replacing hard ground by porous ground, it is concluded that the ground with lowest flow resistivity i.e. grassland left untouched and allowed to grow wild gives the best attenuation performance. However, dividing a single width of soft ground into alternating strips of hard and soft surfaces does not improve the insertion loss. The overall width of the soft surface is the main factor. Cultivating crops over porous ground can enhance the attenuation but the effect is not very significant for A-weighted levels as most of additional attenuation occurs at higher frequencies above 3 kHz. A 0.3 m high and at least 3 m wide lattice structure design is found to be very useful for traffic noise attenuation since it offers greater insertion loss than the same width and height of parallel low walls and the resulting attenuation is azimuthal angle independent. It has been shown also that the potentially negative effect on insertion loss due to propagation of roughness-induced surface waves over rough surfaces can be reduced by introducing sound absorbing material in between the walls

Factors Affecting Cotton Production in Pakistan:Empirical Evidence from Multan District

This paper attempts to examine the factors affecting cotton production in Multan region using primary source of data. A sample of 60 small farmers, 25 medium and 15 large farmers was randomly selected from two Tehsils namely Multan and Shujabad of district Multan. The Cobb-Douglas Production Function is employed to assess the effects of various inputs like cultivation, seed and sowing, irrigation, fertilizer, plant protection, inter-culturing / hoeing and labour cost on cotton yield. The results depicted that seed, fertilizer and irrigation were found scarce commodity for all category of farmers in district Multan. The Cobb-Douglas Production Function results revealed that the coefficients for cultivation (0.113) and seed (0.103) were found statistically significant at 1 percent level. The Cost-Benefit Ratio for the large farmers was found higher (1.41) than that of small (1.22) and medium (1.24) farmers. There is a dire need to ensure the availability of these scarce inputs by both public and private sectors as these inputs were major requirement of the cotton crop.Cotton; Cobb- Douglas Production Function; Cost Benefit Ratio; Marginal Value Product; Allocate Efficiency of Critical Inputs; Multan District; Pakistan

Development of 3D boundary element method for the simulation of acoustic metamaterials/metasurfaces in mean flow for aerospace applications

Low-cost airlines have significantly increased air transport, thus an increase in aviation noise. Therefore, predicting aircraft noise is an important component for designing an aircraft to reduce its impact on environmental noise along with the cost of testing and certification. The aim of this work is to develop a three-dimensional Boundary Element Method (BEM), which can predict the sound propagation and scattering over metamaterials and metasurfaces in mean flow. A methodology for the implementation of metamaterials and metasurfaces in BEM as an impedance patch is presented here. A three-dimensional BEM named as BEM3D has been developed to solve the aero-acoustics problems, which incorporates the Fast Multipole Method to solve large scale acoustics problems, Taylor’s transformation to account for uniform and non-uniform mean flow, impedance and non-local boundary conditions for the implementation of metamaterials. To validate BEM3D, the predictions have been benchmarked against the Finite Element Method (FEM) simulations and experimental data. It has been concluded that for no flow case BEM3D gives identical acoustics potential values against benchmarked FEM (COMSOL) predictions. For Mach number of 0.1, the BEM3D and FEM (COMSOL) predictions show small differences. The difference between BEM3D and FEM (COMSOL) predictions increases further for higher Mach number of 0.2 and 0.3. The increase in difference with Mach number is because Taylor’s Transformation gives an approximate solution for the boundary integral equation. Nevertheless, it has been concluded that Taylor’s transformation gives reasonable predictions for low Mach number of up to 0.3. BEM3D predictions have been validated against experimental data on a flat plate and a duct. Very good agreement has been found between the measured data and BEM3D predictions for sound propagation without and with the mean flow at low Mach number.</p

Postural Orthostatic Tachycardia Syndrome in Young Diabetics

Postural orthostatic tachycardia syndrome is a condition characterized by imbalance in autonomic reactivity leading to exaggerated heart rate and other symptoms of orthostatic intolerance. In adolescents, it is characterized either by a continuous increase in heart rate of ≥40 bpm as compared to basal heart rate or sustained basal rate of ≥130 bpm.         The objective of the research was to compare the characteristics of adolescent diabetics with postural orthostatic tachycardia syndrome with the controls.         Methods. Seventy adolescents diagnosed with type 1 diabetes mellitus who were treated at the department of Endocrinology, Government Medical College and Shri Maharaja Hari Singh hospital, Srinagar, J&amp;K, India were selected for the study. Lying to standing test was performed. Heart rate was recorded at the 2nd, 3rd, 5th and 10th minutes. Based on the results of lying to standing test, there were selected 25 diabetic adolescents with postural orthostatic tachycardia syndrome. Their characteristics were compared with age- and sex-matched adolescents using unpaired T test. P&lt; 0.05 was considered significant.         Results.  We observed a significantly lower body mass index (p=0.027), as well as a significantly higher fasting blood glucose level (p&lt;0.0001) in diabetics with postural orthostatic tachycardia syndrome.         Conclusion. It may be concluded that lower body mass index and higher fasting blood glucose level may lead to the development of postural orthostatic tachycardia syndrome in adolescents.

Key Challenges for Establishing CIO Position in the Public Sector of LDCs: A Case of Bangladesh

Unprecedented growth of information and communications technology (ICT), calls for new public management, pressure from donors, citizen demand, and, above all, the government’s “Digital Bangladesh” political pledge provide impetus for integrating ICT in the public sector of Bangladesh. Despite efforts, the country cannot make sufficient progress in ICT due to the lack of IT structure led by a chief information officer (CIO) or similar leadership position. Although the literature describes various aspects of CIO including role effectiveness, competencies and structural relationship, it does not offer any prescriptive measure on how the CIO position should be established. Drawing on institutional theory, this research identifies critical challenges to establishing the CIO position in the public sector of Bangladesh. In-depth interviews with various stakeholders at different levels of the public sector reveal two critical challenges: a lack of organizational structure, and a lack of commitment at a policy level

The Nexus of Ethical Leadership, Job Performance, and Turnover Intention: The Mediating Role of Job Satisfaction

This study aims to examine the impact of ethical leadership on employees’ job satisfaction, performance, and turnover intention. A conceptual framework is developed which clearly integrates job satisfaction as a mediating mechanism in explaining the nexus among ethical leadership, job performance, and turnover intention. This framework is then analysed employing data from a sample (n = 114) of tourist companies in Lahore, Pakistan. The results reveal that ethical leadership has positive effect on employees’ job satisfaction, performance and has negative effect on their turnover intentions. Further, job satisfaction positively mediates the effect of ethical leadership on employees’ job performance and turnover intentions. The findings recommend that the demonstration of ethical leadership behaviours by managers at workplace enhances employees’ job satisfaction and performance, and decreases the intention of employees to leave the job. The main narrative of this study encompasses the imperative role of ethical leadership in the workplace where it serves as a factor that enhances employees’ job satisfaction, performance, and decreases turnover intention. This research explicitly demonstrates that in Pakistani tourism sector, ethical leadership plays a vital role to achieve performance goals. Future research could analyse the said nexus in different sectors and cultures, and may also consider other measures of individual performance. The consideration of job satisfaction as mediating variable in probing the linkages among ethical leadership, job performance, and turnover intention in the context of the workplace in Pakistan and the analysing of this linkage is novel

Job stress and performance nexus in tourism industry: A moderation analysis

The aim of this research was to examine the impact of job stress on performance (creativity and in-role performance) of employees working in tourism sector of Pakistan. Over and above the direct effect of stress on performance, this study also proposes and empirically tests the moderating effects of social support and perceived organizational politics. Social support is proposed to have positive moderating effect such that higher level reduces, whereas lower level of social support enhances the adverse effect of stress on performance. Contrary to this, perceived organizational politics is suggested as negative moderator where a greater level of perceived organizational politics increases the negative effect of stress on performance. Data were collected from 322 employees working in tourism organizations of Pakistan and were analyzed using hierarchical regression analysis. Findings suggest that employees with higher level of stress perform poor on both creativity and in-role performance. Further, if employees are provided low social support at workplace, it increases the detrimental effect of stress on employee creativity and in-role performance. In addition to that, the findings highlight that higher level of organizational politics catalyzes the detrimental effect of stress on performance. Findings imply that tourist firms can foster employee creativity and in-role performance by providing social support and facilitating workplace environment to cope with stress and organizational politics

Air-borne acoustic surface waves generated over a periodic rough surface

A surface composed of regularly-spaced rectangular strips is known to produce airborne acoustic surface waves that travel slower than the speed of sound and attenuate in the propagation direction with the square root of distance. Further laboratory measurements of propagation over a regular array are reported which seem to indicate the possibility of more than one surface wave. A code based on the Boundary Element Method has been extended to the time domain. It has been used to compare the data and to explore the surface wave effects. Varying the spacing, thickness and height of the strips is shown to affect the magnitude and frequency content of the air-borne surface waves generated by the periodic strip surface

Marketing Analytics Implementation Strategies Exploration for Organizational Transformation at Askari Cement: A Case Study Analysis

Marketing Analytics is a strategic shift where companies need to explore and identify the managerial dynamics of marketing analytics in terms of the implementation strategies that are adapted or preferred by the management for transforming the organisation. This study is about the same in terms of a cement manufacturing company. As much of the research concerning the problem area is focused on IT-intensive companies, this research endeavour would enrich the current research in terms of mapping the marketing analytics implementation strategies for organisational transformation in a developing economy