Modeling quasi-static magnetohydrodynamic turbulence with variable energy flux

In quasi-static MHD, experiments and numerical simulations reveal that the energy spectrum is steeper than Kolmogorov's $k^{-5/3}$ spectrum. To explain this observation, we construct turbulence models based on variable energy flux, which is caused by the Joule dissipation. In the first model, which is applicable to small interaction parameters, the energy spectrum is a power law, but with a spectral exponent steeper than -5/3. In the other limit of large interaction parameters, the second model predicts an exponential energy spectrum and flux. The model predictions are in good agreement with the numerical results.Comment: 16 pages, 5 figure

Wave Inundation on the Coral Coast of Fiji

The roaring winds of the Southern Ocean and the Tasman Sea can generate some large swells, big enough to cause inundation on the Coral Coast in the south west of Viti Levu in Fiji, some 3000 km to the north. These inundation events are sometimes associated with tsunami-like long waves that hit the shore and inundate the coast with brute force. These are locally known as loka waves. To understand the origin of the loka waves and how they become so destructive in a fringing reef environment, this research monitored the waves and water levels, for 2 years, at 4 locations across the reef at a pilot site in Maui Bay on the Coral Coast of Fiji. In order to test the size of waves necessary to cause coastal inundation, a validated numerical model, XBeach, was used to simulate the development, propagation and dissipation of these infragravity waves using different water level scenarios. The result of this analysis is intended as a predictive tool to evaluate the risk of coastal inundation from ocean surface waves that can be used to support an early warning system and coastal management tool for both the tourism industry and coastal communities on the Coral Coast

Incidentally detected solid pseudopapillary neoplasm of pancreas in a child with an ovarian cyst: a case report

Solid pseudopapillary neoplasms (SPN) are the most common as well as very rare pediatric tumors of the pancreas. Most of the literature is derived from adult SPNs. As per world health organization, these tumors considered as low grade malignant with excellent survival outcomes after complete surgical resection. We report a case of incidentally detected SPN in a 16-year-old female child with an ovarian cyst. She underwent pylorus preserving pancreaticoduodenectomy and ovarian cystectomy. Histopathology revealed well differentiated SPN of the pancreas head and ovarian cystadenoma. She is symptom-free at the 6th month follow up

EXPERIMENTAL INVESTIGATION ON PERFORMANCE AND EMISSION ANALYSIS OF CI ENGINE FUELLED WITH TAMANU BIO-DIESEL AND DIESEL USING ADDITIVE

In the current energy scene of fossil fuel, renewable energy sources such as biodiesel, bio-ethanol, bio-methane, and biomass from waste and hydrogen have become the subjects of great interest. These fuels contribute to the reduction of dependence on fossil fuels. In addition, energy sources such as these could partially replace the use of those fuels which are responsible for environmental pollution and may be scarce in the future. Vegetable oil cannot be directly used in the diesel engine for its high viscosity, high density, high flash point and lower calorific value. So it needs to be converted into biodiesel to make it consistent with fuel properties of diesel. A large variety of plants that produce non-edible oils can be considered for biodiesel production such as Tamanu (Calophyllum Inophyllum), Jatropha Curcas (Ratan Jyot), Pongamia Pinnata (Karanja) and Melia Azadirachta (Neem) etc., are easily available in developing countries and are very economical comparable to edible oils. Transport vehicles greatly pollute the environment through emissions such as CO, CO2, NOx, un-burnt or partially burnt HC and particulate emissions. Fossil fuels are the chief contributors to urban air pollution and major source of Green House Gases (GHG) and considered to be the prime cause behind the global climate change. Though diesel fuelled Compression Ignition Engine can operate at high thermal efficiency creates more emission of HC and CO, the high level of NOx poses problems. The high combustion temperature and lean mixtures used are the reasons. This work presents the results of performance and emission analysis carried out in a non-modified diesel engine fuelled with Tamanu Bio- Diesel, Di-ethyl Ether (DEE) its blends with diesel. Engine tests have been conducted to get the comparative measures of Brake Specific Fuel Consumption (BSFC), Indicated Brake Thermal Efficiency (IBTE), Mechanical Efficiency (ME), Brake Thermal Efficiency (BTE), Volumetric Efficiency and Emissions such as HC, CO, NOx and Exhaust gas temperature

Waves and Coasts in the Pacific - Cost Analysis of Wave Energy in the Pacific

Ocean waves are often cited as an appealing source of renewable energy in the Pacific but the cost effectiveness of wave energy converters (WECs) is deemed unproven and the technology is rarely considered as a reliable renewable energy resource in Pacific Island countries. However, single/stand-alone WECs could be a competitive option against fossil fuel generators because of the high cost of imported fuel. This study analyses the wave energy resource in the Pacific and calculates the potential cost and power generation of a benchmark WEC in Pacific Island countries. The type of WEC chosen depends largely on the environmental and geophysical characteristics of the wave energy site where it is to be deployed. The aim of this study was not to report on the best device for each site but rather to give advice about the islands that could benefit most from wave energy. Therefore, the cost analysis is based on a single WEC – the Pelamis device. The Pelamis device cost presented here serves as a benchmark for comparison with other WECs in different locations. Due to uncertainties and variations in potential costs across the region, the study evaluated the range of costs applicable to the whole region. The costs of the WEC, transport, installation, operation and management, refit and decommissioning are included. Site-specific potential power generation was calculated, based on a realistic power output dependent on the wave conditions. The study found that Pacific islands south of latitude 20oS receive a substantial amount of wave energy with a mean available wave resource above 20 kilowatts per metre (kW/m) and that many other islands also have potential for wave energy extraction with a mean wave resource above 7 kW/m. This study found that a Pelamis device in the Pacific could cost between USD 6,318,000 and USD 14,104,000 to install and can operate for 25 years. The energy produced by such a device could be up to 1200 megawatt hours (MWh) per year for sites exposed to large swells. Using these values, the range of the total lifetime cost of power generation was calculated to be between USD 200/MWh for exposed sites and USD 1800/MWh for more sheltered sites. The corresponding operation and maintenance generation cost are between USD 40/MWh and USD 900/MWh. These costs are on a par with the cost of generation of other renewable energies, such as wind and solar, and, for exposed sites, on a par with the cost of diesel generation. These findings suggest that wave energy is a genuine contender for the development of renewable energy in the Pacific and should no longer be ignored when planning such development; a concerted effort from all stakeholders should be made in order to benefit from this technology. Further deployment in wave technology will reduce the cost of single wave energy devices, and most small Pacific Islands would not need to deploy large-scale wave farms of ten or more devices, as power production would greatly exceed the demand. With expected rises in fuel prices in the next decades, it would be wise to investigate further the potential of wave energy technology. The deployment of WECs in the Pacific could provide an opportunity for the technology to prove itself in the region and attract the attention of investors, policy makers and decision makers to invest in wave energy development in the Pacific . Page | 2 Waves and Coasts in the Pacific Other recommendations are listed below. 1. French Polynesia, the Austral Islands in particular, should investigate potential wave energy sites. On these islands, wave energy generation could become a major renewable energy resource with a relatively low cost that could even compete with fossil fuel. 2. Tonga, Cook Islands and New Caledonia should also investigate wave energy sites and suitable wave energy devices. Wave energy has a great potential for helping these countries reach their renewable energy targets and supply energy more cheaply than other renewable energy resources. 3. Countries with a mean wave energy flux above 7 kW/m should also investigate wave energy hotspots and wave energy device options, especially in exposed locations. There, wave energy may be able to supply a significant amount of renewable energy and help these countries meet their renewable energy targets. However, wave energy in these locations may be more expensive than other types of renewable energy. 4. Countries with a mean wave energy flux of less than 7 kW/m, such as Papua New Guinea and Solomon islands, are unlikely to benefit from wave energy unless a major technological breakthrough makes wave energy devices much more efficient. These countries should therefore not consider wave energy as a significant renewable energy resource. The WACOP project has provided calculations similar to those presented in this study for more than 200 Pacific locations in wave climate reports that should be consulted as an initial assessment of the wave energy resource available.1 The WACOP project also provides a detailed wave climate analysis for Samoa, Rarotonga in Cook Islands, Tongatapu and 'Eua in Tonga, southern Viti Levu in Fiji, Efate in Vanuatu, and Funafuti in Tuvalu. These analyses include wave energy and cost calculations based on the calculations presented in this report

Radiation and Soret Effects of MHD Nanofluid Flow over a Moving Vertical Moving Plate in Porous Medium

We analyzed the magneticfiled, radiation and soret effects of a nanofluid flow over a moving vertical plate in porous medium. We considered two types of nanofluids namely Cu-Ethylene glycol, CuO-Ethylene glycol. The governing partial differential equations of the flow are transformed to ordinary differential equations by using similarity transformation and then solved numerically. The effects of non-dimensional governing parameters namely volume fraction of nano particles,  magneticfiled parameter, radiation parameter, soret number, buoyancy parameter and porosity parameter on the flow, temperature and concentration profiles are discussed and presented graphically. Also, the friction factor and Nusselt and Sherwood numbers are discussed and given in tabular form for two nanofluids separately. Keywords: MHD, Radiation, Soret effect, Porous medium, Nanofluid