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121.
As laser–plasma interactions access ever-increasing ranges of plasma temperatures and densities, it is interesting to consider
whether they will some day shed light on questions concerning nuclear synthesis. One such open question is the process of
endothermic nuclear synthesis for elements with A > 60, thought to have taken place at a point in time during the big bang, or currently in supernovae. We present an explanation
based on a Boltzmann equilibrium condition, in combination with the change of the Fermi-statistics from the relativistic branch
for hadrons from higher than nuclear densities to the lower density subrelativistic branch. The Debye length confinement of
nuclei breaks down at the relativistic change, thus leading to the impossibility of nucleation of the quark-gluon state at
higher than nuclear densities. Taking the increment for the proton number Z as Z′ = 10 of the measured standard abundance distribution (SAD) of the elements for a Boltzmann probability for heavy element
synthesis, a sequence 3
n
was found with the exponent n for the sequence of the magic numbers. The jump between the magic numbers 20 and 28 does not need then the usual spin-orbit
explanation. 相似文献
122.
Abstract Monthly evaporation was estimated from the coastal and open waters in the central region of the Red Sea between latitudes 21 and 22°N. A recent equation based on the bulk aerodynamic method was used to calculate the evaporation using two sets of observations collected over the coastal and open waters. The annual evaporation from coastal water was 194 cm with a maximum in May and a minimum in October; from open water, it was 144 cm with a maximum and a minimum in November and September, respectively. The application of Sverdrup's (1937) equation was attempted, first when the roughness parameter z0 in his equation was set equal to 0.6 cm as he proposed, and when z0 was set equal to the most acceptable value of 0.01 cm. Our study shows that the evaporation values obtained in the first case are closer to those obtained either from the recent equation or from direct measurements than those obtained in the second case. 相似文献
123.
The Eastern Pontides orogenic belt in the Black Sea region of Turkey offers a critical window to plate kinematics and subduction polarity during the closure of the Paleotethys. Here we provide a brief synthesis on recent information from this belt. We infer a southward subduction for the origin of the Eastern Pontides orogenic belt and its associated late Mesozoic–Cenozoic magmatism based on clear spatial and temporal variations in Late Cretaceous and Cenozoic arc magmatism, together with the existence of a prominent south-dipping reverse fault system along the entire southern coast of the Black Sea. Our model is at variance with some recent proposals favoring a northward subduction polarity, and illustrates the importance of arc magmatism in evaluating the geodynamic milieu associated with convergent margin processes. 相似文献
124.
125.
The River Buyukmelen is located in the province of Duzce in northwest Turkey and its water basin is approximately 470 km2. The Aksu, Kucukmelen and Ugursuyu streams flow into the River Buyukmelen. It flows into the Black Sea with an output of 44 m3 s−1. The geological succession in the basin comprises limestone and dolomitic limestone of the Yılanlı formation, sandstone, clayey limestone and marls of the Akveren formation, clastics and volcano‐clastics of the Caycuma formation, and cover units comprised of river alluvium, lacutrine sediments and beach sands. The River Buyukmelen is expected to be a water source that can supply the drinking water needs of Istanbul until 2040; therefore, it is imperative that its water quality be preserved. The samples of rock, soil, stream water, suspended, bed and stream sediments and beach sand were collected from the Buyukmelen river basin. They were examined using mineralogical and geochemical methods. The chemical constituents most commonly found in the stream waters are Na+, Mg2+, SO2−4, Cl− and HCO3− in the Guz stream water, Ca2+ in the Abaza stream water, and K+ in the Kuplu stream water. The concentrations of Na+, K+, Ca2+, Mg2+, SO2−4, HCO−3, Cl−, As, Pb, Ni, Mn, Cr, Zn, Fe and U in the Kuplu and Guz stream waters were much higher than the world average values. The Dilaver, Gubi, Tepekoy, Maden, Celik and Abaza streams interact with sedimentary rocks, and the Kuplu and Guz streams interact with volcanic rocks. The amount of suspended sediment in the River Buyukmelen in December 2002 was 120 mg l−1. The suspended and bed sediments in the muddy stream waters are formed of quartz, calcite, plagioclase, clay (kaolinite, illite and smectite), muscovite and amphibole minerals. As, Co, Cd, Cr, Pb, Ni, Zn and U have all accumulated in the Buyukmelen river‐bed sediments. The muddy feature of the waters is related to the petrographic features of the rocks in the basin and their mineralogical compositions, as most of the sandstones and volcanic rocks (basalt, tuffite and agglomerate) are decomposed to a clay‐rich composition at the surface. Thus, the suspended sediment in stream waters increases by physical weathering of the rocks and water–rock interaction. Owing to the growing population and industrialization, water demand is increasing. The plan is to bring water from the River Buyukmelen to Istanbul's drinking‐water reservoirs. According to the Water Pollution Regulations, the River Buyukmelen belongs to quality class 1 based on Hg, Cd, Pb, As, Cu, Cr, Zn, Mn, Se, Ba, Na+, Cl−, and SO2−4; and to quality class 3 based on Fe concentration. The concentration of Fe in the River Buyukmelen exceeds the limit values permitted by the World Health Organization and the Turkish Standard. Because water from the River Buyukmelen will be used as drinking water, it will have an adverse effect on water quality and humans if not treated in advance. In addition, the inclusion of Mn and Zn in the Elmali drinking‐water reservoir of Istanbul and Fe in the River Buyukmelen water indicates natural inorganic contamination. Mn, Zn and Fe contents in the waters are related to geological origin. Moreover, the River Buyukmelen flow is very muddy in the rainy seasons and it is inevitable that this will pose problems during the purification process. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
126.
A. I. Gamal el Din I. A. Issa A. M. I. Osman F. Y. Kamal 《Astrophysics and Space Science》1992,190(1):89-117
Results about the standard photometric parameters of four galaxies are given. The equivalent and the integrated parameters defined according to de Vaucouleurs are listed. Effective values of the abovementioned ingredients, the reduced luminosity profiles and the dimensions defined by the quartiles are also given. 相似文献
127.
We expand the principal part of the planetary disturbing function, by Smart's method, using Taylor's theorem. In our expansion we neglect terms of degree higher than the fourth in the eccentricities and tangents of the inclinations.Now at the JPL Pasadena, California. 相似文献
128.
The coprecipitation method is widely used for the preconcentration of trace metal ions prior to their determination by flame atomic absorption spectrometry (FAAS). A simple and sensitive method based on coprecipitation of Fe(III) and Ni(II) ions with Cu(II)‐4‐(2‐pyridylazo)‐resorcinol was developed. The analytical parameters including pH, amount of copper (II), amount of reagent, sample volume, etc., were examined. It was found that the metal ions studied were quantitatively coprecipitated in the pH range of 5.0–6.5. The detection limits (DL) (n = 10, 3s/b) were found to be 0.68 µg L?1 for Fe(III) and 0.43 µg L?1 for Ni(II) and the relative standard deviations (RSD) were ≤4.0%. The proposed method was validated by the analysis of three certified reference materials (TMDA 54.4 fortified lake water, SRM 1568a rice flour, and GBW07605 tea) and recovery tests. The method was successfully applied to sea water, lake water, and various food samples. 相似文献
129.
N. Ayten Uyanık Osman Uyanık Filiz Gür İbrahim Aydın 《Environmental Earth Sciences》2013,68(2):499-506
Some of the rocks and soil-originated materials used in building construction are the serious natural radiation sources. Soil-originated bricks and roof-tiles and their raw material in the Salihli-Turgutlu area were tested in situ for natural radiation levels using a gamma-ray spectrometer. The concentrations of the radioelements 40K, 238U and 232Th and air-absorbed radiation rates were measured for soil, raw material heaps, brick and roof-tile stacks and waste brick heaps. The radium-equivalent activity Raeq of the raw material varied between 187.9 and 216.4 Bq kg?1. The external radiation hazard index Hex values ranged between 0.51 and 0.58. For building material and its products, recommended Raeq and Hex levels are 370 Bq kg-1 and 1.0, respectively. On the other hand, both Raeq and Hex values for waste brick heaps, containing broken brick pieces, coal pieces and ash, were higher than the recommended levels, i.e. Raeq values varied from 473.8 to 651.0 Bq kg-1 and Hex values were within the range 1.15–1.76. The annual dose rate and radium-equivalent activity values of the brick and roof-tiles were below the level of criteria. Annual dose rate ranged between 0.42 and 0.62 mSv y?1 and radium equivalent activity was in the range 172.9–245.2 Bq kg?1. The external and internal radiation hazard indices were all below the value of 1.0 for the Salihli-Turgutlu area bricks and roof-tiles. Results of this study were compared with results of previous studies. Natural radiation levels of construction raw material of study area are generally higher than of those of previous studies. 相似文献
130.
Fuzzy control of piezoelectric friction dampers for seismic protection of smart base isolated buildings 总被引:1,自引:0,他引:1
This study proposes two fuzzy logic controllers (FLCs) for operating control force of piezoelectric friction dampers used
for seismic protection of base-isolated buildings against various types of earthquake excitations. The first controller employs
a hierarchic control strategy in which a higher-level supervisory controller operates a single sub-level FLC by modifying
its input normalization factors in order to determine command voltage of the damper according to current level of ground motion.
The second controller is a self organizing FLC that employs genetic algorithms in order to build a knowledge base for the
fuzzy controller. Numerical simulations of a base-isolated building are conducted to evaluate the performance of the controllers.
For comparison purposes, an optimal controller is also developed and considered in the simulations together with maximum passive
operation of the friction damper. Results for several historical ground motions show that developed fuzzy logic controllers
can effectively reduce isolation system deformations without the loss of potential advantages of seismic base isolation. 相似文献