The presence of supposedly primitive human tools along the upper reaches of the Kizil Irmak in Anatolia

Die ersten Angaben über Flußterrassen in Ost-Anatolien wurden vor kurzem durch Izbirak (1962) und Ketin (1962) gemacht. Die Verfasser der vorliegenden Arbeit haben eine rasche und noch oberflächliche Exploration eines Terrassensystems von fünf bis sieben verschiedenen Niveaus ausgeführt entlang dem oberen Lauf des großen Kizil Irmak (des Roten Flusses) zwischen Sivas und Kayseri in Ost-Anatolien. Teilweise ist es die von Izbirak beschriebene Gegend, größtenteils geht sie aber über diese hinaus. Die Terrassenflächen sind ziemlich gleichmäßig entwickelt entlang des genannten Teils des Flusses, verschwinden aber plötzlich weiter unterhalb. Die Verfasser meinen mit Izbirak, daß die Entstehung dieser Terrassen wahrscheinlich in erster Linie tektonisch und erst an zweiter Stelle klimatisch bedingt ist. Die dritte Terrasse (von unten an gezählt) enthielt überall eine nur geringe Zahl vermutlicher primitiver Artefakten, unter ihnen einige „pebble-tools". Diese sind in vorliegendem Aufsatz beschrieben; sie stellen vielleicht einen Beweis für die Anwesenheit von frühpleistozänen Hominiden in der Türkei dar. In einem Fall wurde in dieser dritten Terrasse ein fossiler Molar eines Hipparion in situ gefunden, teilweise bedeckt mit demselben versteinerten roten Lehm, welcher auch einige der vermutlichen Artefakten einhüllte. Das Alter der Terrassen ist noch nicht genau bekannt. Es scheint aber, daß die ältesten und höchstgelegenen Tertiär sind, die Terrasse, welche die Artefakten enthält, vielleicht dem untersten Pleistozän angehört, und die untersten Terrassen in das junge Pleistozän oder gar Holozän zu stellen sind.researc

Reducing cross-flow vibrations of underflow gates: experiments and numerical studies

An experimental study is combined with numerical modelling to investigate new ways to reduce cross-flow vibrations of hydraulic gates with underflow. A rectangular gate section placed in a flume was given freedom to vibrate in the vertical direction. Holes in the gate bottom enabled leakage flow through the gate to enter the area directly under the gate which is known to play a key role in most excitation mechanisms. For submerged discharge conditions with small gate openings the vertical dynamic support force was measured in the reduced velocity range 1.5 < Vr < 10.5 for a gate with and without holes. The leakage flow through the holes significantly reduced vibrations. This attenuation was most profound in the high stiffness region at 2 < Vr < 3.5. Two-dimensional numerical simulations were performed with the Finite Element Method to assess local velocities and pressures for both gate types. A moving mesh covering both solid and fluid domain allowed free gate movement and two-way fluid-structure interactions. Modelling assumptions and observed numerical effects are discussed and quantified. The simulated added mass in still water is shown to be close to experimental values. The spring stiffness and mass factor were varied to achieve similar response frequencies at the same dry natural frequencies as in the experiment. Although it was not possible to reproduce the vibrations dominated by impinging leading edge vortices (ILEV) at relatively low Vr, the simulations at high Vr showed strong vibrations with movement-induced excitation (MIE). For the latter case, the simulated response reduction of the ventilated gate agrees with the experimental results. The numerical modelling results suggest that the leakage flow diminishes the whipping effect of fluctuations at the trailing edge associated with the streamwise pressure drop across the gate and the body's vertical oscillatory motion.Comment: 27 pages, 15 figures, 2 table

Evolutionary Design of Numerical Methods: Generating Finite Difference and Integration Schemes by Differential Evolution

Classical and new numerical schemes are generated using evolutionary computing. Differential Evolution is used to find the coefficients of finite difference approximations of function derivatives, and of single and multi-step integration methods. The coefficients are reverse engineered based on samples from a target function and its derivative used for training. The Runge-Kutta schemes are trained using the order condition equations. An appealing feature of the evolutionary method is the low number of model parameters. The population size, termination criterion and number of training points are determined in a sensitivity analysis. Computational results show good agreement between evolved and analytical coefficients. In particular, a new fifth-order Runge-Kutta scheme is computed which adheres to the order conditions with a sum of absolute errors of order 10^-14. Execution of the evolved schemes proved the intended orders of accuracy. The outcome of this study is valuable for future developments in the design of complex numerical methods that are out of reach by conventional means.Comment: 19 pages, 7 figures, 10 tables, 4 appendice

Mio-Pliocene Faunal Exchanges and African Biogeography: The Record of Fossil Bovids

The development of the Ethiopian biogeographic realm since the late Miocene is here explored with the presentation and review of fossil evidence from eastern Africa. Prostrepsiceros cf. vinayaki and an unknown species of possible caprin affinity are described from the hominid-bearing Asa Koma and Kuseralee Members (∼5.7 and ∼5.2 Ma) of the Middle Awash, Ethiopia. The Middle Awash Prostrepsiceros cf. vinayaki constitutes the first record of this taxon from Africa, previously known from the Siwaliks and Arabia. The possible caprin joins a number of isolated records of caprin or caprin-like taxa recorded, but poorly understood, from the late Neogene of Africa. The identification of these two taxa from the Middle Awash prompts an overdue review of fossil bovids from the sub-Saharan African record that demonstrate Eurasian affinities, including the reduncin Kobus porrecticornis, and species of Tragoportax. The fossil bovid record provides evidence for greater biological continuity between Africa and Eurasia in the late Miocene and earliest Pliocene than is found later in time. In contrast, the early Pliocene (after 5 Ma) saw the loss of any significant proportions of Eurasian-related taxa, and the continental dominance of African-endemic taxa and lineages, a pattern that continues today

Free-surface flow simulations for discharge-based operation of hydraulic structure gates

We combine non-hydrostatic flow simulations of the free surface with a discharge model based on elementary gate flow equations for decision support in the operation of hydraulic structure gates. A water level-based gate control used in most of today's general practice does not take into account the fact that gate operation scenarios producing similar total discharged volumes and similar water levels may have different local flow characteristics. Accurate and timely prediction of local flow conditions around hydraulic gates is important for several aspects of structure management: ecology, scour, flow-induced gate vibrations and waterway navigation. The modelling approach is described and tested for a multi-gate sluice structure regulating discharge from a river to the sea. The number of opened gates is varied and the discharge is stabilized with automated control by varying gate openings. The free-surface model was validated for discharge showing a correlation coefficient of 0.994 compared to experimental data. Additionally, we show the analysis of CFD results for evaluating bed stability and gate vibrations