Canonical structure of BHT massive gravity in warped AdS3 sector

We investigate the asymptotic structure of the three dimensional warped anti de sitter black holes in the Bergshoeff, Hohm and Townsend massive gravity using the canonical Hamiltonian formalism. We define the canonical asymptotic guage generators, which produce the conserved charges and the asymptotic symmetry group for the warped anti de sitter black holes. The attained symmetry group is described by a semi direct sum of a Virasoro and a KacMoody algebra. Using the Sugawara construction, we obtain a direct sum of two Virasoro algebras. We show that not only the asymptotic conserved charges satisfy the first law of black hole thermodynamics, but also they lead to the expected Smarr formula for the warped anti de sitter black holes. We also show that the black hole entropy obeys the Cardy formula of the dual conformal field theory .Comment: 13 page

Black Holes in Born-Infeld Extended New Massive Gravity

In this paper we find different types of black holes for the Born-Infeld extended new massive gravity. Our solutions include (un)charged warped (A)dS black holes for four and six derivative expanded action. We also look at the black holes in unexpanded BI action. In each case we calculate the entropy, angular momentum and mass of the black holes. We also find the central charges for the CFT duals.Comment: 23 pages, 5 figure

Modelling of hydraulic fracturing in unconventional reservoirs

Hydraulic fracturing (HF) is a process of fluid injection into the well in order to create tensile stresses in the rock to overcome the tensile strength of the formation. In this study, the development and application of a fuzzy model to predict the efficiency of hydraulic fracturing is presented with application in a coal mine as an unconventional reservoir. The most important parameters affecting the HF process of a coal seam are: dip, thickness, seam uniformity, roof and floor conditions, reserve of coal seam and coal strength. In the developed model, the efficiency of hydraulic fracturing of coal seams is calculated as a dimensionless numerical index within the range 0-100. The suggested numerical scale categorizes the efficiency of HF of seams to very low, low, medium, high and very high, each one being specified by a numerical range as a subset of the above range (0-100). HF in the coal bed in PARVADEH 4 Tabas mine in Iran is investigated as a case study. The results show that the developed model can be used to identify seams that have high potential for HF Moreover, a three-phase hydro-mechanical model is developed for simulating hydraulic fracturing. The three phases include: porous solid, fracturing fluid and reservoir fluid. Two numerical simulators (ANSYS Fluent for fluid flow and ANSYS Mechanical for geomechanical analysis) are coupled together to model multiphase fluid flow in hydraulically fractured rock undergoing deformations, ranging from linear elastic to large, nonlinear inelastic deformations. The two solvers are coupled, using system coupling in ANSYS Workbench. The coupled problem of fluid flow and fracture propagation is solved numerically. The fluid flow model involves solving the Navier-Stokes equations using the finite volume method. The flow model is coupled with the geomechanics model to simulate the interaction between fluid flow inside the fracture with rock deformations. For any time step, the pore pressures from the flow model are used as input for the geomechanics model for the determination of stresses, strains, and displacements. The strains derived from the gomechanics model are in turn used to calculate changes to the reservoir parameters that are fed as input to the flow model. This iterative process continues until both (fluid and solid) models are converged. The laboratory-scale study of hydraulic fracturing in the Second White Specks (SWS) shale was simulated using the developed model. The numerical and experimental results were compared. Comprison of the results shows that the numerical model can predict the behaviour of the shale under hydraulic fracturing with a good accuracy

Emergency Decision Making and Disaster Recovery

There is growing evidence that the number and severity of natural disasters and their cascading events such as power blackouts are increasing. These extreme events threaten human lives, displace hundreds of thousands of people and cause huge financial losses. Therefore, it is important to understand better how socio-economic systems can best respond to these disasters and how they can recover quickly, build back better and become more resilient. This thesis comprises five separate studies of four different types of disasters. The overall objective is to improve the understanding of how society copes with and makes decisions in crisis and emergency situations, and how disaster affected areas recover, particularly in terms of speed and quality. This is a huge subject and rather than focusing on just one event or a single type of disaster, the objective is to look at different types of disaster events by studying people’s risk perception and their (real or expected) disaster behaviour in the context of different phases of the disaster cycle from immediate response to longer-term recovery and resilience building. The five studies featured in this thesis are: 1. Behaviour during a long-lasting blackout in France and Germany, investigated through role-playing scenario exercises to study how society would cope. The aim is provide information to emergency managers and policy makers about community needs and people’s likely behaviour in future blackouts, 2. Analyses of people’s preparedness, perception and behaviour during floods in the UK and Germany and their attitude to public authorities, investigated through face-to-face interview surveys with people living and working in the flood prone areas, 3. Analyses of flood evacuation compliance, from both decision-theoretic and game-theoretic perspectives, using the Warning Compliance Model, which incorporates a Bayesian information system that formalizes the statistical effects of a warning forecast based on the harmonious structure of a Hidden Markov Model, 4. Examining recovery after two major comparable floods in UK and Germany in terms of the impacts, levels of preparedness and government response, investigated with face-to-face interview surveys with residents and businesses and online surveys with experts, 5. Tourist destination recovery in the Philippines after earthquake and typhoon, investigated through interviews with tourist managers and stakeholders. The key areas for future research revolve around identifying in more detail and with greater precision those factors that predispose a society to respond effectively to a disaster, to recover as quickly as possible and to build resilience in order to better confront future disasters

Walnut shell extract as sustainable, eco-friendly and cost-effective green corrosion inhibitor for fabrication of active protective nanocomposite coating based on mesoporous carbon hollow nanospheres

This paper presents anticorrosion performance of epoxy resin containing walnut extract as green inhibitor doped in mesoporous carbon hollow nanospheres (MCHNSs). In the first step, mesoporous silica hard templating method was used to fabricate carbon hollow nanospheres. In the second step, the extracted green inhibitor was loaded into the nanospheres (WE@MCHNSs) and on-demand active coating was fabricated by uniformly dispersing doped carbon nanospheres in epoxy matrix. The corrosion protection properties of the coatings were studied by electrochemical impedance spectroscopy (EIS), electrochemical noise measurement (ENM) and salt spray analysis. Corrosion resistance of the mild steel samples in the 3.5 wt. % NaCl solution in the presence and absence of walnut extract was compared. Salt spray and electrochemical impedance spectroscopy (EIS) results proved active protective behavior of the epoxy coating containing the doped MCNSs. It was shown that charge transfer resistance of the bare steel sample enhanced from ~ 610 Ω cm2 to ~ 4060 Ω cm2 in the presence of WE after 24 h immersion time. Also, the active corrosion protective performance of the scribed coatings was improved ~ 1450 % in the presence of WE@MCHNSs. The obtained results revealed that on-demand release of walnut green inhibitors from carbon nanospheres enhance protection performance of epoxy coatings. Furthermore, the fabricated epoxy coating demonstrated active protection behavior due to release of inhibitor caused by mechanical damage of carbon nanospheres shells (Figure 1). Please click Additional Files below to see the full abstract