Chain transfer to the solvent in the poly-merisation of styrene at high pressures

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Analysis of Self-Excited Synchronous Reluctance Generator

A steady-state model and a transient model of self-excited synchronous reluctance generator are developed for stand-alone operation. Saturation is considered to predict the actual behavior of the machine. The proposed linearized model is applied to obtain eigenvalues for steady-state stability analysis under different loading conditions. The effects of active, reactive, apparent power output and excitation capacitance on the steady-state performance of self-excited synchronous reluctance generator are analyzed. Eigen value sensitivity is calculated by varying circuit parameters from 50% to 0% of their standard values at 100 μF, 125 μF and 150 μF excitation capacitances. The proposed transient model is applied to observe the transient behavior of machine such as load angle, speed and electromagnetic torque when the machine is subjected to a three-phase symmetrical short-circuit fault across the machine terminals. The load angle sensitivity to machine circuit parameters is investigated

Unsteady newtonian and non-newtonian fluid flows in the circular tube in the presence of magnetic field using caputo-fabrizio derivative

This thesis investigates analytically the magnetohydrodynamics (MHD) transport of Newtonian and non-Newtonian fluids flows inside a circular channel. The flow was subjected to an external electric field for the Newtonian model and a uniform transverse magnetic field for all models. Pressure gradient or oscillating boundary condition was employed to drive the flow. In the first model Newtonian fluid flow without stenotic porous tube was considered and in the second model stenotic porous tube was taken into account. The third model is concerned with the temperature distribution and Nusselt number. The fourth model investigates the non-Newtonian second grade fluid velocity affected by the heat distribution and oscillating walls. Last model study the velocity, acceleration and flow rate of third grade non-Newtonian fluid flow in the porous tube. The non-linear governing equations were solved using the Caputo-Fabrizio time fractional order model without singular kernel. The analytical solutions were obtained using Laplace transform, finite Hankel transforms and Robotnov and Hartley’s functions. The velocity profiles obtained from various physiological parameters were graphically analyzed using Mathematica. Results were compared with those reported in the previous studies and good agreement were found. Fractional derivative and electric field are in direct relation whereas magnetic field and porosity are in inverse relation with respect to the velocity profile in Newtonian flow case. Meanwhile, fractional derivative and Womersely number are in direct relation whereas magnetic field, third grade parameter, frequency ratio and porosity are in inverse relation in third grade non-Newtonian flow case. In the case of second grade fluid, Prandtl number, fractional derivative and Grashof number are in direct relation whereas second grade parameter and magnetic field are in inverse relation. The fluid flow model can be regulated by applying a sufficiently strong magnetic field

Optical and electron microscopic studies on indented silicon carbide crystals

The static indentation hardness test has been applied to the study of the environment effects on hardness, plastic deformation, and fracture properties of silicon carbide crystals. Measurements of microhardness on the (0001) planes show that the hardness of silicon carbide is significantly lowered by water absorbed from the air. Upon annealing the crystals, at very high temperatures, the hardness is found to increase. A three-dimensional distribution of stress, beneath an indenter, has been evaluated using 'elastic equations'. The mechanics of crack initiation around the contact circle of a spherical indenter with the specimen has been analysed. The crack extension force, for a crack propagating downward from the surface of the specimen, has been evaluated. Evidence of plastic deformation by slip is provided by a number of indentations, specially those with the spherical and double-cone indenters. (1010) is the preferred slip plane.<p

Behaviour of fibre reinforced cemented sand at high pressures

Several well established techniques of soil stabilisation and soil reinforcement are available to improve properties of geotechnical materials. However, the addition of fibre into soils has its unique potential as a reinforcing agent. This is because a friction between fibre and soil particles increases the bonding between the particles of soils and this can improve the plasticity, stress-strain behaviour and failure characteristics of both cemented and uncemented soils. It also reduces the brittleness of the cemented sand. Numerous experiments on fibre-reinforced granular materials have been carried out by several researchers. However, the behaviour of fibre-reinforced cemented granular soils has not been fully understood yet. Furthermore, most experimental studies of fibre reinforced cemented materials have been carried out at relatively low confining pressures. As a result, more experiments are still needed to understand complicated behaviour of soil-cement-fibre composite materials. The main objective of this thesis is to analyse the behaviour of fibre reinforced cemented sand under wide range of confining pressures. For this GDS high pressure triaxial cell apparatus and Bishop and Wesley conventional triaxial cell apparatus have been used to carry out the tests at wide range of confining pressures from 50kPa to 20MPa. Drained and undrained tests have been carried out on polypropylene fibre reinforced sand with and without the addition of cement. Samples with varying fibre and cement content were prepared by the method of undercompaction and were cured for 28 days prior to testing. The experimental results indicate that there is a significant effect from the addition of fibre and/or cement contents and confining pressures on the mechanical behaviour of Portaway sand. Particularly, these effects were noted in drained and undrained triaxial tests, particularly peak strength, strength parameters, shear banding, particle crushing, yielding, and stress-dilatancy relationships. The addition of fibres increases the peak, yield, and ultimate strengths. Increase in confining pressure also increases the strength but the individual effect of the addition of fibres was more pronounced at low confining pressures. Progressive suppression in the dilation by the gradual increase in confining pressures as well as an increase in dilation with the addition of fibres during triaxial compression was also worth noticeable. Although, no noticeable affect was observed in isotropic compression due to the addition of fibre in both cemented and uncemented sand. An extensive series of tests were carried out but due to time constraint only one type and length of fibre was used. Therefore, more research needs to be carried out at different fibre lengths and types in order to see that whether these change the behaviour observed in this research

EFFECT OF ROLE CONFLICT AND ROLE AMBIGUITY ON EMPLOYEE CREATIVITY

The objective of the present study was to investigate the effects of role conflict and role ambiguity on employee’s creativity. Exactly how role stress and various performances of individuals are related has received considerable attention, in which stress has been found to affect individual creativity. However, exactly how role stress (role conflict and role ambiguity) and employee creativity are related has seldom been examined empirically. A sample size of 100 was selected and standard questionnaires were distributes among the employees of three public sector universities in Peshawar KPK Pakistan. The conclusions drawn from the study were that role conflict and role ambiguity have negative relationship with employees creativity. Implications of the findings of this study and possible directions for future research are also discussed

Modification of Neutron Kinetic Code for Plate Type Fuel Nuclear Reactor

The research is conducted on the modification of neutron kinetic code for the plate type fuel nuclear reactor. REMARK is a neutron kinetic code that works only for the cylindrical type fuel nuclear reactor. In this research, our main emphasis is on the modification of this code in order to be applicable for the plate type fuel nuclear reactor. For this purpose, detailed mathematical studies have been performed and are subjected to write the program in Fortran language. Since REMARK code is written in Fortran language, so we have developed the program in Fortran and then inserted it into the source library of the code. The main emphasis is on the modification of subroutine in the source library of the code for hexagonal fuel assemblies with plate type fuel elements in it. The number of steps involved in the modification of the code has been included in the paper. The verification studies were performed by considering the small modular reactor with hexagonal assemblies and plate type fuel in it to find out the power distribution of the reactor core. The purpose of the research is to make the code work for the hexagonal fuel assemblies with plate type fuel element

The Role of Intracranial Pressure (ICP) Monitoring in Severe Traumatic Brain Injury (TBI)

The management of patients with severe head injury is a prodigious task for any neurosurgical team. After the initial life support, the management plan of patient with traumatic brain injury rest on the findings of a cranial CT scan. The treatment options of TBI differ with severity of trauma. Osmotic diuretics in the acute phase can be helpful. Hyperventilation is a method to be used in conjunction with other options in certain situations. Normal values of intra cranial pressure (ICP) vary with age, being 10 to 15 mm Hg in an adult. Intra cranial pressure (ICP) values of 20 to 30 mm Hg shows mild intracranial hypertension, while sustained intra cranial pressure (ICP) values more than 40 mm Hg indicate life threatening malignant intracranial hypertension which should be lowered immediately. Measuring the intra cranial pressure of severe traumatic brain injury patients is now mandatory as it allows an effective and control way of lowering the raised ICP with very good outcome results.Objective: To adjust the ICP lowering mechanics according to the reading obtained via the ICP monitor in patients after severe head injury so as to minimize the need of ventilatory support and decrease the patients’ stay at hospital.1. To measure the value of ICP by using ICP monitoring in severe head injuries (GCS score below or equal to 8).2. To assess the outcome of the conservative measures in patients in whom ICP was monitored, on the basis of Glasgow Outcome Scale.Study Design: Prospective descriptive study.Setting: Department of Neurosurgery, Lahore General Hospital, Lahore.Duration of Study: One year from July 2012 to July 2013.Material and Methods: Thirty patients of traumatic brain injury were included in this study. ICP monitoring was done via Integra intra parenchymal Camino bolt and Integra ICP monitors.Results: Out of 30 patients, there were 21 (70%) male patients and 9 (30%) female patients.The male to female ratio was 2.33:1. In 20 (67%) patients the ICP ranged from 25-34 mmHg. There were 10 (33%) patients having ICP of 35 – 50 mm Hg. The mean intracranial pressure was 29.5 ± 6.96. The Glasgow coma scale of our patients was such that there were2 (6.6%) patients had GCS 5. In GCS 6 there were 20 (66%) patients. There were 3 (10%) patients who had a GCS of 7. In GCS 8 there were 5 (16.6) patients. The ventilation duration was 5 – 15 days. The frequency of hospital stay in our patients 10-30 days. There were 2 (7%) patients of Glasgow outcome scale of grade – I. In grade – II, there were 3 (10%) patients, no patient in Glasgow outcome scale grade – III. There were 10 (33%) patients in grade – IV while 15 (50%) patient were in grade – V. In the follow up cases, after 1 month, there were no patient in grade – I. There were 3 (10%) patients of GOS grade – II, in grade – III there were 4 (13%) patients, there were 8 (27%) patients grade – IV. 15 (50%) patients of grade – V. After 3 month, there was 1 (3%) patient in grade – I. There were 2 (7%) patients of GOS grade – II, in grade – III there&nbsp;were 2 (7%) patients, there were 10 (33%) patients grade – IV. 15 (50%) patients of grade – V.Conclusion: It is concluded that ICP monitoring is useful for improving the outcome of traumatic brain injury patients. Most of the patients were in young age. Majority of the patients had a low Glasgow coma scales. In our study most of the patients were male. In this study there is short duration of ventilation in patients and a short hospital stay in patients of TBI in which ICP is monitored and addressed promptly

Dysembryoplastic Neuroepithelial Tumour (DNET): A Rare Brain Pathology Presenting with Intractable Seizures

Dysembryoplastic neuroepithelial tumour (DNET) is a benign glioneuronal tumour often related with intractable localization – related seizures in both in paediatric age group as well as young adults. However, a small number appear to have the potential for malignant transformation. Total surgical removal without any adjuvant therapy is the gold standard treatment. We report a case in which DNET appeared in a 13 year old male. Cranial CT scan showed a discoid lesion with peripheral enhancement in right parietal lobe. Micro-decompression of the tumour was done. On histopathology, the tumour revealed features of WHO grade I dysembryoplastic neuroepithelial tumour