Investigation of high-pressure turbulent jets using direct numerical simulation

Direct numerical simulations of free round jets at a Reynolds number ($Re_{D}$) of $5000$, based on jet diameter ($D$) and jet-exit bulk velocity ($U_{e}$), are performed to study jet turbulence characteristics at supercritical pressures. The jet consists of $\mathrm{N_{2}}$ that is injected into $\mathrm{N_{2}}$ at same temperature. To understand turbulent mixing, a passive scalar is transported with the flow at unity Schmidt number. Two sets of inflow conditions that model jets issuing from either a smooth contraction nozzle (laminar inflow) or a long pipe nozzle (turbulent inflow) are considered. By changing one parameter at a time, the simulations examine the jet-flow sensitivity to the thermodynamic condition (characterized in terms of the compressibility factor ($Z$) and the normalized isothermal compressibility), inflow condition, and ambient pressure ($p_{\infty}$) spanning perfect- to real-gas conditions. The inflow affects flow statistics in the near-field (containing the potential core closure and the transition region) as well as further downstream (containing fully-developed flow with self-similar statistics) at both atmospheric and supercritical $p_{\infty}$. The sensitivity to inflow is larger in the transition region, where the laminar-inflow jets exhibit dominant coherent structures that produce higher mean strain rates and higher turbulent kinetic energy than in turbulent-inflow jets. Decreasing $Z$ at a fixed supercritical $p_{\infty}$ enhances pressure and density fluctuations (normalized by local mean pressure and density, respectively), but the effect on velocity fluctuations depends also on local flow dynamics. When $Z$ is reduced, large mean strain rates in the transition region of laminar-inflow jets significantly enhance velocity fluctuations (normalized by local mean velocity) and scalar mixing, whereas the effects are minimal in jets from turbulent inflow.Comment: In pres

Health and hygiene situation in northern areas of Pakistan: pre and post WASEP interventions

The overarching goal of Water and Sanitation Extension programme (WASEP) is to reduce diarrhoeal morbidity by 50% in its partner communities. WASEP includes water supply, sanitation, drainage, water quality and health and hygiene education in its interventions. To calculate the possible impact of health oriented intervention, it is very important to have knowledge of existing health situation and it is always valuable to know about local beliefs and practices concerning hygiene behavior. Unfortunately, hygiene education has been an ignored subject and has not been key objective to the organizations responsible for providing rural water supply schemes and has never been an attractive option to the villagers of Northern areas and Chitral. Health should be one of the prime objectives for investing money in a water supply and Sanitation programmes. The prevailing situation requires a thorough thought to address this subject. There is a large vacuum in this field, which needs to be filed with better planning. There are many aspects of rural life in the Northern Areas and Chitral region of Pakistan where people have unhygienic traditional practices. Unfortunately, sometimes these unhygienic practices are linked with beliefs and religions. Some people for example believe that all flowing water is clean i.e. river; channels etc. regardless of its source. Also, cloths after washing with soap are not considered clean (Paak) if not dipped in water at least one meter deep. Women are main procurer and user of water and entirely responsible for sanitation and hygiene of the family at home. In many parts of northern areas, acute shortage of water, ignored sanitation and hygiene have made life difficult for women. A water and sanitation programme, should therefore involve women in the development process. The central role of women in water, sanitation and hygiene has been emphasized in throughout WASEP’s five years progamme. WASEP has been aiming to provide safe water at injection rather than at source or at tap stand. As discussed above, women shoulder responsibility of providing water to their families. Therefore, primary target group was the women who also carry out the risk practices. i.e. cleaning children, handling children’s stool and responsible for excreta disposal

Photocatalytic Reduction of Co2 Using Zns Pillaring on Kaolin Catalyst

Increasing of carbon dioxide (CO2) concentration in atmosphere has gain major attention by the researchers. This is due to CO2 ability to absorb heat from the UV light and emits the heat to atmosphere resulted in earth warming. In order to overcome this problem, the researchers come out with many solutions. Conventional method and also Advanced Oxidation Process (AOP) have been invented as a way to reduce the concentration of the predominant greenhouse gases especially CO2. However, AOP has come out as the emerging technologies due to its practicality in reduction process in industry. This study will be focusing on one of the AOP which is photocatalytic reduction process of CO2. In this process, a photocatalyst was needed. In this research, photocatalyst used was ZnS-Kaolin, a combination of semiconductor ZnS and phyllosilicate mineral, Kaolin. ZnS-Kaolin was prepared by using two methods which are hydrothermal method and simpler impregnation method. In this photocatalytic reduction process, the catalyst was dispersed in medium solution, NaOH aqueous and hence help to catalyze the process. The characteristics of the developed ZnS-Kaolin were observed by using Scanning Electron Microscope (SEM) and Thermal Gravimetric Analyzer (TGA). The effect of parameters such as irradiation time and dosage of ZnS-Kaolin used were observed and studied. This process was produced usable products such as methanol and was analyzed by using High Performance Liquid Chromatography (HPLC). Based on the results, from SEM analysis, it was found that raw Kaolin was constructed from hexagonal flakes structure. Meanwhile, both ZnS-Kaolin prepared from Hydrothermal and Impregnation methods are consists of leaf-like layers structure with ZnS nanoparticles deposited on Kaolin structure. From TGA analysis, it was found that ZnS-Kaolin prepared from Hydrothermal method has higher thermal resistance compared to ZnS-Kaolin prepared from Impregnation method. Meanwhile, for photoreduction process of CO2, methanol production was observed to be maximum by using ZnS-Kaolin prepared from Hydrothermal method at dosage of 0.75 g and at 2 hours irradiation time. In conclusion, ZnS-Kaolin prepared by using Hydrothermal method shows better performance in photoreduction process of CO2 compared to ZnS-Kaolin prepared from Impregnation method

Combating diamond theft through intelligence-led and technology-based solutions : case study Cullinan Diamond Mine, South Africa

Criminology and Security ScienceM. Tech. (Security Management

Investigation of high-pressure turbulent jets using direct numerical simulation

Direct numerical simulations of free round jets at a Reynolds number (Re_D) of 5000, based on jet diameter (D) and jet-exit bulk velocity (U_e), are performed to study jet turbulence characteristics at supercritical pressures. The jet consists of Nitrogen (N₂) that is injected into N₂ at same temperature. To understand turbulent mixing, a passive scalar is transported with the flow at unity Schmidt number. Two sets of inflow conditions that model jets issuing from either a smooth contraction nozzle (laminar inflow) or a long pipe nozzle (turbulent inflow) are considered. By changing one parameter at a time, the simulations examine the jet-flow sensitivity to the thermodynamic compressibility factor (Z), inflow condition, and pressure (p) spanning perfect- to real-gas conditions. The inflow affects flow statistics in the near-field (containing the potential core closure and the transition region) as well as further downstream (containing fully-developed flow with self-similar statistics) at both atmospheric and supercritical p. The sensitivity to inflow is larger in the transition region, where the laminar-inflow jets exhibit dominant coherent structures that produce higher mean strain rates and higher turbulent kinetic energy than in turbulent-inflow jets. Decreasing Z at a fixed supercritical ambient pressure (p∞) enhances pressure and density fluctuations (non-dimensionalized by local mean pressure and density, respectively), but the effect on velocity fluctuations depends also on local flow dynamics. When Z is reduced, large mean strain rates in the transition region of laminar-inflow jets significantly enhance velocity fluctuations (non-dimensionalized by local mean velocity) and scalar mixing, whereas the effects of decreasing Z are minimal in jets from turbulent inflow

Polytechnic Commerce Students Personality Factors In Relations To Their Preparedness Towards Workplace

Malaysian Polytechnic students joining the workforce are expected to be highly educated, have good personality and well prepared. Employees’ personality have great impact on their behavior and performance at the workplace. Therefore knowledge of individual personality can lead to a more effective human resource management. Over the years, due to Malaysian economic growth, the workplace has undergone significant changes in the sense that workers need to prepare themselves with technical skills and good personality in order to be successful. The purpose of the study was to investigate if there was any positive significant relationship between commerce students personality factors with their preparedness towards workplace. It was hypothesized that students with high self-esteem self-monitoring and locus of control would have performed better in terms of industrial training performance, academic achievement and perceived ability to understand and perform at workplace. The methodological approach was systematic random sampling using a structured, 68 items questionnaire which was distributed to 252 marketing, accounting and business students at the six polytechnics in Malaysia. 199 questionnaires were returned and analyzed. The independent variables (self-esteem, self-monitoring, locus of control) and the dependent variables (ability, academic performance and industrial training performance) were analyzed using Pearson correlations coefficient and Stepwise regression methods in the SPSS. It was found that there was a positive significant relationship between self-monitoring and students perceived ability to understand and perform at the workplace. However there was no significant relationship between students self-esteem and locus of control with their preparedness towards workplace. Commerce students need self-monitoring in their sales and marketing tasks in order to be successful in the heterogeneous market environment in Malaysia. Personality factors like self-esteem, self-monitoring and locus control can be developed in students by proper training. It was recommended that further research on this subject be conducted with larger sample size and by taking into consideration of other factors such as teaching methods, length of training and the relevancy of course contents

Economic Literacy amongst the Secondary School Teachers in Perak Malaysia

The aim of the study is to determine the relationship between economics education exposure, saving, expenditure, investment and economics literacy amongst teachers in secondary schools in Perak. The theoretical framework was designed based on the literature and hence five hypotheses for the study were formulated. The samples were selected by quota sampling methods. The data were collected by distributing structured 35 items questionnaires to 100 teachers in secondary schools in eight districts in Perak. The instrument was adapted form Leader Behaviour Description Questionnaires which were used to measure economic literacy. Only 60 questionnaires were returned and analysed which gave 60% respond rate. Data collected were sorted out and keyed in into SPSS version 17. The data were analysed using descriptive and inferential statistics to answer the research questions. The result of the analyses showed that there was significant relationship between economics education and its predictors. Together the independent variables explained 81.7% of the variance in the dependent variables. The remaining 18.3% was due to unidentified variables. In relation to that, the study had contributed some knowledge about the understanding of economic of literacy. For future research, it is recommended that other than the above variables might influence economic literacy perhaps with a bigger samples and wider scope

The development of deniable authentication protocol based on the bivariate function hard problem

A deniable authentication protocol enables a receiver to identify the true source of a given message but not to prove the identity of the sender to the third party. Non-interactive protocol is more efficient than interactive protocol in terms of communication overhead, and thus several non-interactive deniable authentication protocols have been proposed. So, it is very necessary to design a deniable authentication protocol which is non-interactive, secure and efficient. This paper proposes a deniable authentication protocol based on the bivariate function hard problem (BFHP) cryptographic primitive. An improvement based on the BFHP is suggested since the problem of the BFHP provides the needed security elements plus its fast execution time. At the same time, the proposed protocol has properties of completeness, deniability, security of forgery attack, security of impersonation attack and security man-in-the-middle attack also has been proved