Mandibular Layering in Delphinapterus leucas and Age Determination
LAWS1 investigated mandibular periosteal layers as an aid to ageing the Sperm whale Physeter catodon. Continued studies of P. catodon indicate that mandibular layers and tooth layers occur in equal numbers2, and it has been postulated that two tooth layers are deposited annually3. Two tooth and one mandibular layer in Delphinus delphis are annual4.
Laminated Structure of Bones from Some Marine Mammals
IN recent years much attention has been paid to methods of age determination for marine mammals, and several reliable techniques are now available. Ovarian corpora albicantia counts1,2, baleen plate ridges3, internal growth layers in the dentine and cementum of teeth4, and laminations in the ear plug of baleen whales5 are in use. Certain of these techniques have been applied with success to some terrestrial mammals, notably the method based on tooth structure6,7. In other species, marine and terrestrial, these methods cannot be used.
Techno-economic analysis of solar thermal power plants using liquid sodium as heat transfer fluid
Abstract Solar thermal power plants with central receiver and thermal storage are expected to be one key technology in future electricity generation, because they are renewable and due to the thermal storage independent of the current solar radiation. State-of-the-art solar power plants often use molten nitrate salts as heat transfer fluid. The use of liquid sodium instead leads to lower electricity generation costs. Sodium has a high thermal conductivity and thus large heat transfer rates are possible. Hence, a smaller absorber surface is sufficient for the same thermal power. As a result, the sodium receiver achieves a higher efficiency at lower investment cost. Additionally, the aiming strategy, which reduces the peak heat flux on molten salt receivers isn’t necessary for sodium. Even at high heat flux densities, the absorber tubes will be cooled sufficiently due to the high heat transfer coefficients. Therefore, the sodium receiver in this analysis is designed for one single aim point, resulting in a heat flux density of q mean = 1.06 MW / m 2 and q peak = 2.99 MW / m 2 . The state-of-the-art system with molten salt considers q mean = 0.51 MW / m 2 and q peak = 1.0 MW / m 2 . The presented techno-economic analysis of two sodium based concepts compared to a reference system with molten salt results in up to 16% lower electricity generation costs.