Study of Magnetization Switching in Coupled Magnetic Nanostructured Systems using a Tunnel Diode Oscillator

Static techniques to measure different magnetic properties of coupled magnetic nanostructured systems is researched and documented with an extensive analysis of the tunnel diode oscillator (TDO). The VSM was used to obtain the major hysteresis loop for the samples and the TDO was used to measure the magnetic susceptibility. The magnetic susceptibility was employed to conceive the static critical curve. The thesis describes both equipments, VSM and TDO, that were used to obtain data for our experiments. Albeit a more comprehensive outlook on the TDO is provided. The theoretical functionality of TDO, previous successful applications for experiments, and the physical setup in the laboratory is explored. The novel addition of the double Helmholtz coil in this setup is described. The viability of replacement of the big electromagnet and the advantages of the Helmholtz coil are discussed. Magnetization dynamics in a series of FeCoB/Ru/FeCoB synthetic antiferromagnetic samples were investigated via reversible susceptibility measurements acquired through the TDO. The major hysteresis loop generated by the VSM were used to calculate the coercivity and magnetic saturation of the sample. The VSM and TDO were subsequently used to explore the magnetization switching in a di_erent coupled magnetic system, the exchange bias samples. A range of NiFe/FeMn samples were studied with varying thickness of the antiferromagnetic layer

Valuation and Pricing of Surface Water Supplies in Pakistan

Pakistan has the largest contiguous, well-articulated, and comprehensive irrigation system in the world, with 3 storage reservoirs, 68 small dams, 19 diversion barrages, and 45 canal commands with 12 Link Canals for inter-basin transfer of water. About 0.1 million outlets supply water to the farmers to irrigate land besides more than 600,000 tubewells. The whole irrigation network commands an area of 45 million acres (18.22 Mha) out of which 79 percent is irrigated by canals or tubewells/wells. More than half of the canal irrigated areas (58 percent) is irrigated perennially and 42 percent nonperennially [NWSR (2002)]. The average annual flow of Indus River System is approximately 151.58 million acre feet (MAF) of which presently 103.81 MAF (128.1 BCM) is being diverted to irrigate farm lands [NWSR (2002)]. The present live storage capacity of the reservoirs is about 12.5 MAF (13 percent of river flows) compared with the original capacity of 15.7 MAF. The hydropower generation is constrained by seasonal inflows to reservoirs and irrigation requirements by Indus River System Authority. The generation dictated by irrigation requirements is the highest in the months of July to October. Little more than half of the diverted flows (55 percent) become available at farm gate, 42 percent infiltrate to groundwater reservoir and balance 3 percent is lost as evaporation. Of the total water that seeps down to the groundwater reservoir, including some 27 percent of farm gate supply through field seepage, nearly 85 percent is being extracted. Groundwater owing its existence to operational canal system, supplies over 40 percent of crop water requirements of the countr

Study of Magnetization Switching in Coupled Magnetic Nanostructured Systems using a Tunnel Diode Oscillator

Static techniques to measure different magnetic properties of coupled magnetic nanostructured systems is researched and documented with an extensive analysis of the tunnel diode oscillator (TDO). The VSM was used to obtain the major hysteresis loop for the samples and the TDO was used to measure the magnetic susceptibility. The magnetic susceptibility was employed to conceive the static critical curve. The thesis describes both equipments, VSM and TDO, that were used to obtain data for our experiments. Albeit a more comprehensive outlook on the TDO is provided. The theoretical functionality of TDO, previous successful applications for experiments, and the physical setup in the laboratory is explored. The novel addition of the double Helmholtz coil in this setup is described. The viability of replacement of the big electromagnet and the advantages of the Helmholtz coil are discussed. Magnetization dynamics in a series of FeCoB/Ru/FeCoB synthetic antiferromagnetic samples were investigated via reversible susceptibility measurements acquired through the TDO. The major hysteresis loop generated by the VSM were used to calculate the coercivity and magnetic saturation of the sample. The VSM and TDO were subsequently used to explore the magnetization switching in a di_erent coupled magnetic system, the exchange bias samples. A range of NiFe/FeMn samples were studied with varying thickness of the antiferromagnetic layer

Three Essays Of Assessing The Risk, Adaptation And Resilience To Natural Disasters

This dissertation consists of three chapters in environmental and natural resource economics. In the first chapter, using survey data, I investigate what factors are important in people\u27s evacuation decisions in the coastal areas of Bangladesh. I examine if temporal spillover is present in their decision making and how significant the spillover effect is. With that objective in mind, I examine the effect of previous evacuation experience on future evacuation decision. I also analyze how network effects influence people\u27s evacuation decisions during a natural disaster. As the threat of climate change grows, communities around the world are facing the dangers of encountering different kinds of natural hazards with higher frequency and intensity. When people are dealing with multiple hazards, exposure to one hazard can trigger or change their risk perception about the other hazard. In the second chapter, I use data from Lake County in Florida to analyze spillover effects in terms of multiple hazards. I examine if people are exposed to one type of natural hazard, whether their concern for another type of natural hazard increases or not. To test my hypothesis, in the second chapter, I analyze if exposure to hurricane Irma triggers people\u27s risk perception about their exposure to the risk of sinkhole and how that added risk perception affects the real estate market. Until 2007, the sinkhole insurance policy coverage in Florida was not very well defined, and it was very broad. In 2011, a new legislature was passed by the Florida Senate, narrowing the scope of qualifying damage and including some other provisions. The new law was made applicable from July 2016. In the third chapter, I attempt to capture the effect of this new insurance law on people\u27s risk perception and how that transformed risk perception is reflected in the housing prices. The main focus of this dissertation is to gain a better understanding of the dynamics of different types of spillover effects of risk averting behaviors in response to natural hazard risks

Transmission and Distribution Co-Simulation and Applications

As the penetration of flexible loads and distributed energy resources (DERs) increases in distribution networks, demand dispatch schemes need to consider the effects of large-scale load control on distribution grid reliability. Thus, we need demand dispatch schemes that actively ensure that distribution grid operational constraints are network-admissible and still deliver valuable market services. In this context, this work develops and evaluates the performance of a new network-admissible version of the device-driven demand dispatch scheme called Packetized Energy Management (PEM). Specifically, this work develops and investigates the live grid constraint-based coordinator and metrics for performance evaluation. The effects of grid measurements for a practical-sized, 2,522-bus, unbalanced distribution test feeder with a 3000 flexible kW-scale loads operating under the network-admissible PEM scheme is discussed. The results demonstrate the value of live grid measurements in managing distribution grid operational constraints while PEM can effectively deliver frequency regulation services. Increased penetration of flexible loads and DERs on distribution system (DS) will lead to increased interaction of transmission and distribution (T&D) system operators to ensure reliable operation of the interconnected power grids, as well as the control actions at LV/MV grid in aggregation will have significant impact on the transmission systems (TS). Thus, a need arises to study the coupling of the transmission and distribution (T&D) systems. Therefore, this work develops a co-simulation platform based on decoupled approach to study integrated T&D systems collectively. Additionally, the results of a decoupled method applied for solving T&D power flow co-simulation is benchmarked against the collaborator developed unified solution which proves the accuracy of the decoupled approach. The existing approaches in the literature to study steady-state interaction of TS-DS have several shortcomings including that the existing methods exhibit scalability, solve-time and computational memory usage concerns. In this regard, this work develops comprehensive mathematical models of T&D systems for integrated power flow analysis and brings advancements from the algorithmic perspective to efficiently solve large-scale T&D circuits. Further, the models are implemented in low-cost CPU-GPU hybrid computing platform to further speed up the computational performance. The efficacy of the proposed models, solution algorithms, and their hardware implementation are demonstrated with more than 13,000 nodes using an integrated system that consists of 2383-bus Polish TS and multiple instances of medium voltage part of the IEEE 8,500-node DS. Case studies demonstrate that the proposed approach is scalable and can provide more than tenfold speed up on the solve time of very large-scale integrated T&D systems. Overall, this work develops practically applicable and efficient demand dispatch coordinator able to integrate DERs into DS while ensuring the grid operational constraints are not violated. Additionally, the dynamics introduced in the DS with such integration that travels to TS is also studied collectively using integrated T&D co-simulation and in the final step, a mathematically comprehensive model tackles the scalability, solve-time and computational memory usage concerns for large scale integrated T&D co-simulation and applications

Some approximation results for generalized Kantorovich-type operators

In this paper, we construct a new family of operators, prove some approximation results in A-statistical sense and establish some direct theorems for Kantorovich-type integral operators

Studies on new substituted pyridazinones: synthesis and biological evaluation

We report herein the synthesis and pharmacological evaluation of a new series of 6-aryl-2-(imidazol1-yl/1,2,4-triazol-1-yl)-2-methyl-4,5-dihydro-(2H)-pyridazin-3-one (3a-j) as potential anticonvulsant and antitubercular agents. The title compounds were prepared by reacting 6-aryl-4,5-dihydro-(2H)- pyridazin-3-one (2a-e) with formaldehyde and secondary cyclic amine imidazole or 1,2,4-triazole as per Mannich reaction. Anticonvulsant activity of pyridazinone derivatives was tested at 50 mg.kg-1 dose level against maximal electroshock (MES), isoniazid (INH, 250 mg.kg-1) and pentylenetetrazole (PTZ at 80 mg.kg-1) induced seizure methods. Phenytoin sodium (25 mg.kg-1) and sodium valproate (100 mg. kg-1) were used as reference drugs for comparison purpose. In-vitro antitubercular activity was tested by Microplate Alamar Blue assay (MABA) method and the results were compared with clinically used antitubercular agents such as INH, Pyrazinamide (PZA) and Streptomycin (STM). None of the screened compounds were found to be neurotoxic at a dose level of 100 mg.kg-1. All the screened compounds (3a-j) significantly reduced the MES, INH and PTZ induced convulsions and thus showed good anticonvulsant activity. The minimum inhibitory concentration (MIC) of the title compounds against M. tuberculosis ranged from 1.6 µg/mL to 6.25 µg/mL in comparison to INH, PZA (3.125 µg/mL) and STM (6.25 µg/ mL) which indicated good antitubercular activity

Antigenic diversity of dengue virus: implications for vaccine design

Ph.DDOCTOR OF PHILOSOPH