Umair Najeeb Mughal

Dielectric based sensing of atmospheric ice

Atmospheric ice is a naturally occurring mixture with lots of variations. It doesn’t only bind the chemistry of water, but also its physics. The variations of this complex mixture are directly associated with the surrounding dynamics. In this paper we are mainly concerned about the variations in the electrical properties of atmospheric ice due to variation in the surrounding temperature, conductivities, volumetric contents and relaxation time. All these variations are conveniently measured using the permittivity/dielectric sensing principles. Also these calculations can later be utilized to formulate the atmospheric ice type, icing rate and ice thickness.

Numerical study of atmospheric ice accretion on rotating geometric cross sections with fins

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Design of an Intelligent De-Icing System for Offshore Structures

The offshore activities in cold waters have moved from shallow to deep sea waters, which require different operations as compared to activities in hot sea water. Such offshore operations in cold regions like arctic may be effected by the ice accretion on deck and other areas of structure. Ice mainly accretes from both sea spray and atmospheric icing, which can create problems for operational environment and safety of people working on offshore structures in cold regions. In this research a lab based experimental study has been carried out to preliminary design and test an intelligent thermal anti/de-icing system. The experimental study was carried out in cold room chamber of Narvik University College, where temperature can be well controlled between +10 to-30 °C. The proposed intelligent thermal based deicing system can be used to control the communication between icing sensors, weather station, heating devices and central control unit. In this preliminary design phase, a simple surface temperature control method has been developed and tested that can further provides an efficient thermal deicing method and will also be capable to control the surface temperature of objects of interest in cold regions

Using potential flow theory and conformal mapping technique to measure pressure differential on airfoil

Flow around an airfoil to calculate pressure co-efficient variations at different relative velocities have always been an important/basic part of Aerodynamic Study. Potential flow theory is used to study flow behavior on rankine half body, non-rotating cylinder and rotating cylinder as it is more trackable. Falkan-Skan Similarity Solution is taken to simulate the flow behavior on wedge. However, to use potential flow theory on usable airfoils the author have used conformal mapping to show a relation between realistic airfoil shapes and the knowledge gained from flow about cylinders. This method can further be used in the designing of an airfoil section. The author has used Joukowski Tranform to generate the flow around airfoils of various geometries and then utilized Kutta condition to force the stagnation point at the trailing edge. Co-efficient of pressure over the entire airfoil surface were calculated and corrected using Karman-Tsien compressibility correction equations. On the basis of this, the loca...

State of the art review of semi active control for magnetorheological dampers

Earthquakes causes severe damage to badly designed structures or buildings to fail or collapse, and also have caused some damage to well-designed structures to malfunction due to the damage or failure of the equipment housed in the structure or building. The use magnetorheological dampers to mitigate the effect of external excitation is increased to resolve this. This article is a state of the art review of nonlinear analytical models to understand the efficacy of semi-active control theory for magnetorheological dampers. A nonlinear semi active control law is desired to be designed which atleast guarantees analytical closed loop stability in order to mitigate the effect of perturbations and drive the desired output to equilibrium.Earthquakes causes severe damage to badly designed structures or buildings to fail or collapse, and also have caused some damage to well-designed structures to malfunction due to the damage or failure of the equipment housed in the structure or building. The use magnetorheological dampers to mitigate the effect of external excitation is increased to resolve this. This article is a state of the art review of nonlinear analytical models to understand the efficacy of semi-active control theory for magnetorheological dampers. A nonlinear semi active control law is desired to be designed which atleast guarantees analytical closed loop stability in order to mitigate the effect of perturbations and drive the desired output to equilibrium.

Atmospheric icing intensity on slowly rotating hexagonal prism and cylinder with fins

Atmospheric ice accretion intensities on constantly slowly rotating hexagonal prism with six fins and constantly slowly rotating cylinder with four fins were studied using experimental and mathematical analysis. The experimental intensities were compared with the existing ice accretion intensity models of Makkonen. Based upon this study a forced rotation constant and generalized windward area ratio is proposed to be added in the existing intensity models, in order to validate the experimental observations.

Multiphysics Based Design Study of an Atmospheric Icing Sensor

Partially funded by the Research Council of Norway, project no. 195153 and partially by the consortium of the project ColdTech - Sustainable Cold Climate Technology

A field study of atmospheric icing analysis in a complex terrain of the high north

Analyses of atmospheric icing events hold the key for computing the significant parameters leading to icing load calculations. In the cold regions of the high north, atmospheric icing loads on structures become important when it comes to design and safety of infrastructures. Furthermore, icing load calculations over a certain period of time provide a vital input for designers to improve the safety of structures. Patterns of icing events can be evaluated in correlation with other meteorological parameters such as atmospheric temperature, relative humidity and wind speed to better estimate icing loads. A field study has been performed in the complex terrain of northern Norway, by the atmospheric icing research team of Narvik University College, where customized meteorological atmospheric ice monitoring stations were installed to study atmospheric icing events in relation with the associated weather parameters. The meteorological parameters of three different sites in the vicinity of Narvik (68°25′14′ N17°33′36′ E) were collected, sorted, averaged to standardized timeline and further validated with recordings of weathers parameters obtained from the national weather forecasts, where a good agreement was found. Analyses were mainly performed between accreted ice loads and associated meteorological parameters. The results presented can be used as base for the development of more detailed mathematical models for the better prediction of atmospheric icing events in complex terrains.

Electromagnetism based atmospheric ice sensing technique - A conceptual review

Electromagnetic and vibrational properties of ice can be used to measure certain parameters such as ice thickness, type and icing rate. In this paper we present a review of the dielectric based measurement techniques for matter and the dielectric/spectroscopic properties of ice. Atmospheric Ice is a complex material with a variable dielectric constant, but precise calculation of this constant may form the basis for measurement of its other properties such as thickness and strength using some electromagnetic methods. Using time domain or frequency domain spectroscopic techniques, by measuring both the reflection and transmission characteristics of atmospheric ice in a particular frequency range, the desired parameters can be determined.