An Impedance Cross Correlation (ICC) Device For Measuring Solids Velocity And Volume Fraction Profiles In Solid-Water Flows

Multiphase flow is the simultaneous flow of two or more phases, in direct contact, in a given system. It is important in many fields of chemical and process engineering and in the oil industry, e.g. in production wells and in sub-sea pipelines. The behavior of the flow will depend on the properties of the constituents, the flows and the geometry of the system. Upward inclined solids-liquid flows are sometimes encountered in the process industries for example in water treatment processes and in oil well drilling operations. Measurements of the local solids volume fraction distribution and the local axial solid velocity distribution are important, for example, in measuring the solids volumetric flow rate. This study presents a non-intrusive Impedance Cross- Correlation (ICC) device to measure the local solids volume fraction distribution and the local axial solids velocity distribution in upward inclined solids-water flows in which these distributions are highly non-uniform. The ICC device comprises a non-conductive pipe section of 80mm internal diameter fitted with two arrays of electrodes at planes, A and B, separated by an axial distance of 50mm. At each plane, eight electrodes are equispaced over the internal circumference of the pipe. A control system consisting of a microcontroller and analogue switches is used such that, for planes A and B, any of the eight electrodes can be configured as an ‘excitation electrode’ (V+), a ‘virtual earth measurement electrode’ (ve) or an ‘earth electrode’ (E) so that different regions of the flow cross section can be interrogated. Conductance signals from planes A and B are then cross correlated to yield the solids velocity in the region of flow under interrogation. Experiments were carried out in water-solids flows in a flow loop with an 80 mm inner diameter, 1.68m long Perspex test section which was inclined at 30o to the vertical. The most significant experimental result is that, at the upper side of the inclined pipe, the measured solids velocity is positive (i.e. in the upward direction), whilst at the lower side of the inclined pipe the measured local axial solids velocity is negative (i.e. in the downward direction). This shows quantitative agreement with previous work carried out using intrusive local probes to measure the solids velocity profile. The study also shows qualitative agreement with high speed film of the flow. It is believed that this method of velocity profile measurement is much simpler to implement than dualplane electrical resistance tomography (ERT)

The relevance of specific csfs for stakeholders during ERP implementation: an empirical study from Oman

The success of ERP systems implementation is affected by the extent to which stakeholders have been prepared for the project activities and its outcomes. Stakeholders’ preparation needs change as the ERP implementation lifecycle progresses and varies across stakeholder groups. Therefore a dynamic model is needed for such preparation. However such a model needs to reflect the relevance of different CSFs to different stakeholder groups at different stages of the ERP implementation life-cycle. This study examines empirical evidence from a survey conducted in Omani organisations to determine what these individual CSFs are and how they are distributed across the ERP implementation life-cycle for different stakeholder groups. The CSFs included in the survey were derived from a structured review of literature. Purposive sampling was used to select respondents representing different ERP stakeholders groups, all respondents had both experience and knowledge of ERP implementations. The survey data are analysed and the distribution of relevant CSFs across the ERP lifecycle for the different stakeholder groups are presente

Multi-agent control and operation of electric power distribution systems

This dissertation presents operation and control strategies for electric power distribution systems containing distributed generators. First, models of microturbines and fuel cells are developed. These dynamic models are incorporated in a power system analysis package. Second, operation of these generators in a distribution system is addressed and load following schemes are designed. The penetration of distributed generators (DGs) into the power distribution system stability becomes an issue and so the control of those DGs becomes necessary. A decentralized control structure based on conventional controllers is designed for distributed generators using a new developed optimization technique called Guided Particle Swarm Optimization. However, the limitations of the conventional controllers do not satisfy the stability requirement of a power distribution system that has a high DG penetration level, which imposes the necessity of developing a new control structure able to overcome the limitations imposed by the fixed structure conventional controllers and limit the penetration of DGs in the overall transient stability of the distribution system. Third, a novel multi-agent based control architecture is proposed for transient stability enhancement for distribution systems with microturbines. The proposed control architecture is hierarchical with one supervisory global control agent and a distributed number of local control agents in the lower layer. Specifically, a central control center supervises and optimizes the overall process, while each microturbine is equipped with its own local control agent.;The control of naval shipboard electric power system is another application of distributed control with multi-agent based structure. In this proposal, the focus is to introduce the concept of multi-agent based control architecture to improve the stability of the shipboard power system during faulty conditions. The effectiveness of the proposed methods is illustrated using a 37-bus IEEE benchmark system and an all-electric naval ship

Paper microfluidic sensors towards on-site environmental analysis of soil nutrients

The increase in the world population leads to an increase in the need for production of crops. To optimise crop production fertilizer application needs to be managed by the farmer, consequently, regular information about the chemistry of the soil is required. There is a strong need for regular and in-field methods for the analysis of different essential nutrients in the soil which are in macro (e.g., nitrate) and micro (e.g., manganese) levels. Of the recently available lab techniques (e.g., IEC1, ICP-MS2) and commercial techniques3 (e.g., strips and palintest) some are not quantitative, some are expensive, some are time-consuming, and some combine all these disadvantages. Consequently, they are not practical, especially for low- and middle-income countries where agriculture is the main source of economy.Here a simple (user-friendly) and low-cost workflow for routine monitoring of nitrate and manganese in soil samples, which is based on phone colourimetric paper-based sensor and cafetière extraction and meets on situ detection requirements, was developed.Novel cafetière extraction was suggested for the first time for on-site extraction of soil nutrients. Cafetière consisted of plunger and meshes which provide the required mixing and filtration respectively. Initially nitrate determination workflow in soil was developed and tested with volunteers. The workflow requires 13 minutes total time for nitrate determination, 5 minutes extraction by cafetière (DIW solvent, 90% extraction efficiency) and 8 minutes detection by a phone-based colourimetric paper-based sensor. The PAD (paper-based analytical device) was able to detect as low as 27.10±2.64 mg kg-1 and 34.35±2.77 mg kg-1 of nitrate when a scanner and phone were used for the detection respectively. The developed PAD was small, portable, fast, easy to use, disposable, safe, low cost, robust (to interference and pH change), reliable and can be used in the field in a resource-limited setting. 97% of volunteers found the workflow easy and were able independently to perform the workflow for nitrate determination by following a simple instruction sheet.Similarly, a workflow for manganese determination was developed in the lab to fit the field requirement. The workflow consists of two steps: 4 min cafetière extraction (NaCl solvent, 10% extraction efficiency) and 7 min detection (colourimetric paper-based sensor) with a total time of 11 minutes. The PAD was able to detect (LoD) 4.14±0.30 mg kg-1 and 5.12±1.88 mg kg-1 of manganese when a scanner and phone were used for the detection respectively. The developed PAD was inexpensive, easy to handle (based on dipping sample introduction) and with less toxicThe workflow showed promising results in detecting nutrients in the soil without the aid of an expert. This workflow will enable farmers in low-income countries to determine soil nutrient content using non-expensive, simple, and easily available methods and hence get enough information about the recommended fertilizer application. Consequently, this may improve the crop and hence the economy in these countries. In the future, the workflow needs to be supported with an app that enables the lay people to determine the result of the analysis by themselves and share it with researchers

EFFECTIVE COLLEGE TEACHING AND STUDENTS’ RATINGS OF TEACHERS: WHAT STUDENTS THINK, WHAT FACULTY BELIEVE, AND HAT ACTUAL RATINGS SHOW IMPLICATIONS FOR POLICY AND PRACTICE IN TEACHING QUALITY ASSURANCE AND CONTROL IN HIGHER EDUCATION IN OMAN

This study examines the extent to which teachers’ (N=248) and students’ (N=968) perceptions of effective teaching and students’ evaluations of teachers in six colleges of technology in Oman match or mismatch. It also investigates Omani students’ (N=922) ability to identify the teaching dimensions underlying a widely used American instrument used for collecting students’ evaluations of teachers and the extent to which the teaching dimensions found in Oman are similar to or different from those found in America and elsewhere in the West. In addition, the present research assesses the reliability of students’ ratings in Oman and the effect of a number of course, teacher, and student background characteristics on these ratings. Results showed that while teachers and students matched in their perceptions of various characteristics of effective teaching, they significantly differed in their valuation of many criteria of effective teaching. Differences were also observed between the two groups’ perceptions of the validity and utility of students’ ratings and the role of the student as an evaluator of teaching. The results also showed that Omani students are capable of identifying most of the teaching dimensions underlying the standardised American rating instrument. A few factors, however, appear to be inseparable in the Omani context. The inter-rater reliability of students’ ratings collected from Oman was analysed and found to be of good standard and only slightly lower than what was found in North America and Australia for the same instrument. Consistent with previous research, it appears, however, that students’ ratings are affected by various student, teacher, and course background characteristics. The evidence on the differences between teachers and students in their perceptions of quality college teaching and their criteria for judging teaching effectiveness calls for more investigation and verification. It is argued here that many of the mismatches in perceptions can be traced to students’ educational upbringing in pre-college education. Therefore, the assumption that quality can be improved in higher education irrespective of what learning styles and habits students bring with them from schools may be unrealistic. Contrary to the prevailing stance in Oman’s higher education, which generally views students’ ratings with distrust and suspicion, the present study results appear to provide preliminary support for the use of students’ ratings in Oman’s universities and colleges as a source of information in teaching evaluation and improvement. It is argued that involving students in the evaluation of teaching is an essential tool in implementing, institutionalising, and enhancing the newly introduced standards in teaching and learning

‘They cannot Write as Well as We Expect’, Why? A Multi-Case Study of Stakeholders’ Perceptions of Factors that Hinder Graduates of Colleges of Technology Mastering Technical Writing Skills Requested in the Omani Market

This project addresses a continuing problem in technical education: the perceived mismatch between the report writing skills of technical college graduates and the demands of report writing in the workplace. This problem is commonly identified in surveys of employers, who express dissatisfaction with the writing skills of their new hires, and has most often been examined with surveys of alumni from these colleges, who express dissatisfaction with the writing preparation they received (Al- Mahrooqi & Denman, 2016). The study is specifically designed to find out why graduates of Colleges of Technology (CoT) have difficulty in performing technical report writing tasks as well as expected by workplace managers and how academic text features are different from or similar to professional text features. This project took a new approach to investigating the problem. This multi-case study employed the combined use of semi-structured interviews and document analysis methods. This involved a total of 19 interviews with (1) report writing tutors and courses designers and students in three (COT) and (2) employees and their employers in local telecommunication and banking firms. The project then focused on the empirical analysis of structural and linguistic features in a corpus of 168 reports written by numerous students of CoT and by practitioners from the firms. This combination brought multiple perspectives to the interpretation of the issue being investigated in relation to the different participants, but also contextualised the analysis of the texts within the social and cultural situations from which the participants came. Findings suggested that CoT graduates' experience with writing for workplace purposes in the contexts of the study is influenced by both institutional and contextual factors. These factors interact to hinder the graduates’ mastery of context-appropriate writing. The key institutional factors are a) task requirements, and b) awareness of texts’ audience. The key contextual factor is the absence of coordination between the two investigated contexts, namely CoT and corporates. Within each of these broad categories, there are also subcategories that further demonstrate the complexity of graduates’ writing and the multitude of elements that shape graduates’ writing in both university and future workplace. The thesis concludes by presenting practical and theoretical implications for corporate officials, teachers, and course designers. The study recommends that internal and external communication is needed between CoT and corporates as through the establishment of such effective channels of communication between these camps we will be able to bridge the current perceived gap and better equip graduates for the challenges of workplace writing. It is hoped that in addressing the research aims these findings may be beneficial to understanding the contextual factors that assist or hamper the progress of the undergraduates' technical writing. It is also anticipated that such a comprehension may guide course designers, writing tutors, and discipline lecturers to detect the preparations required to best sustain students' negotiation of technical writing to better prepare students to adapt to the demands of academic and work contexts

Plant-parasitic nematodes associated with alfafa and fluctuations of Pratylenchus jordanensis population in the Sultanate of Oman

Des enquêtes réalisées de 1991 à 1996 dans les gouvernorats de Batimah, de Dhabira et du Dhofar et dans les régions de l'Intérieur et de Shargia ont révélé la présence de treize genres de nématodes phytoparasites associés à la luzerne. Les #Pratylenchus$sont les nématodes les plus communs (61$ spp., #Tylenchorhynchus spp., #Helicotylenchus spp. et #Rotylenchulus reniformis. Les fluctuations de population de #Pratylenchus jordanensis ont été suivies sur luzerne, en deux sites à Rumais dans la région de Bathinah en 1994-1995 et 1995-1996, respectivement. Une corrélation positive (P supérieur ou égal à 0,01) a été observée entre les populations du nématode et la température. Les populations endoracinaires sont les plus élevées de juillet à novembre et les plus basses de décembre à juin. (Résumé d'auteur

A Novel Mobility Control Technique in Miscible Gas Injection Using Direct Gas Thickening in High Pressure and Temperature Reservoir

This thesis presents for the first time, the details of extensive numerical and experimental evaluations of effectiveness of thickened associate gas injectionat high temperature for miscible gas floodingwith specific focus on FieldAlocated in southern Oman. The study has identified commercialand safe gas thickeners capable of increasing viscosity of injected gas. It hasalso proposedanovel alternating injection technique that canlower the volume of thickeners usedduringfield-scale applications

Natural Cooling Techniques For Buildings

Modern development in many Third World countries in the hot regions of the world,, have been accompanied by the construction of highly energy-wasteful buildings. The interiors of these buildings have to be mechanically airconditioned in order to achieve thermal-comfort conditions. The consequence of this, has been the rapid increase in electricity-generating plant capacity to match demand (of which, for example at present in Oman, more than 70% nationally is used for air-conditioning modern, energyinefficient buildings). The aim of this work was to find the most suitable way of stabilising or even reducing the electricity demand in a country like Oman. The first step taken to achieve this aim, was to study and draw out lessons from the vernacular architecture of the different climatic regions in Oman. This has been followed by a literature survey that looks at passive and active natural cooling techniques for buildings in hot climates. Mathematical models were then developed to analyze and compare those passive techniques that are most suitable for an environment like that of Oman. Different ways of reducing the heat gain through the roof were investigated and compared. These include the addition of insulation, shading, air-cooling of the roof when the ambient air temperature is lower than that of the roof, and roof ponds. Roof ponds were found to be the most effective of those techniques analyzed. An improved design of the roof pond (the Water Diode roof pond) that eliminates the need for covering the roof pond during the day and uncovering it at night, was suggested and analyzed. The analysis showed promising results. Mathematical models were also developed to analyze and compare dif f erent ways of reducing the heat gain through the walls. These included the use of closed cavities, naturally ventilated cavities, the addition of insulation, and the effect of using brick as compared to concrete block. The analysis suggested that the combination of a Water Diode roof pond and insulated brick wall construction will reduce the heat gain through the envelope of a single room by more than 90%, when compared to a room with un-insulated roof and single-leaf concrete block walls. An empirical validation of the mathematical models was conducted. The results showed a good agreement between the actual and predicted values. An economical analysis of the commonly used roof and wall constructions in Oman, was also conducted. This compared the life-cycle cost of nine different construction techniques, with eight different airconditioning schedules. The result of this analysis showed a clear advantage of using roof insulation, reflective double glazing, and insulated walls with brick outer-leaf and concrete block inner-leaf

Investigation of gas shale pore structure and its influence on transport properties

Knowledge and understanding of rock properties is essential to determine hydrocarbon storage and recovery. This thesis evaluates the microstructural characteristics of gas shale formations from the Perth Basin, Western Australia. The tools to assess shale’s textures and flow parameters still remain a challenge. In this study numerous techniques such as mercury injection capillary pressure, nuclear magnetic resonance, low pressure nitrogen adsorption and focused ion beam-scanning electron microscopy have been employed to access shale nano scale pore structure