In-line response of a cylinder in oscillatory flow

The most widely used mathematical model to represent flow-induced in-line forces on structures is based on the Morison¹ equation. The present paper investigates the validity of using an extension of Morison's equation for non-stationary structures, by comparing predictions with results from a simple laboratory experiment. An elastically-mounted circular cylinder is placed in the sinusoidal flow of a U-tube, and responds in-line with the flow. Cylinder forces and responses are recorded over a range of Keulegan Carpenter numbers up to 35. An equation of motion is solved simply by using relative coordinates and by employing equivalent linearisation. The linear results are compared over a wide variation of parameters with solutions using the full nonlinear equation. Thereafter experimental results are compared with linear predictions.     

REE geochemistry and isotopic data of Archean silicic volcanics and granitoids from the Pilbara Block,Western Australia: implications for the early crustal evolution

Eighteen silicic volcanic rocks of the Warrawoona Group and ten associated plutonic rocks from the Pilbara Block, Western Australia, have been chosen for geochemical and isotopic studies. Silicic volcanics of the UNSB (Upper member of North Star Basalt) are dated at 3.56—3.57

, by both the Rb-Sr and the Sm-Nd methods. The respective 1 (initial isotopic composition) values are 0.7005 ± 5 (Sr) and 0.50810 ± 39 (Nd). This age is consistent with the stratigraphic interpretation that the TalgaTalga Subgroup, in which the North Star Basalt occupies the lowermost position, is overlain by the Duffer Formation, whose age was earlier established at 3.45

by the zircon U-Pb method. The new Rb-Sr data on six silicic lava samples from the Duffer Formation yield an isochron of 3.23 ± 0.28 (2v). Though imprecise, this age agrees with the zircon age within error limits. Rb-Sr ages of 2.3–2.4.

obtained for the ‘Panorama’ rocks and the Wyman Formation do not correspond to their initial eruption ages. Chemical arguments suggest that these ages represent the time of metasomatism associated with the widespread thermal event in this region about 2.3–2.4

ago.Geochemically, most of these analyzed rocks (volcanic and plutonic) are of tonalite-trondhjemitegranodiorite (TTG) composition, a typical feature found in many other Archean terrains. They generally show fractionated REE patterns, except the Panorama Formation rocks. Furthermore, the Wyman Formation rhyolites and the post-tectonic adamellites show significant negative Eu anomalies, suggesting a similar mode of magma generation and a probable genetic link. Theoretical considerations suggest that most of these TTG rocks could have been generated by partial melting of amphibolitic or basaltic sources, followed by fractional crystallization.Although the Archean granitic gneisses often possess mantle-like I_sr values, the trace element data indicate that they could not have been derived by direct melting of upper mantle materials. The immediate tectonic implication is that in any Archean terrain, the formation of Na-rich continental crust of TTG suite must be preceded by the presence of basaltic crust. The occurrence of this basaltic crust is a matter of controversy. Such crust might have been totally destroyed by repeated melting processes, or its remnants are now represented by some of the mafic-ultramafic enclaves within the tonalite-trondhjemite batholiths.     

Digital modeling studies for evaluation of hydrogeological characteristics in Shadnagar granite basin,Andhra Pradesh,India

The use of digital models has increased significantly in recent years with the accessibility of fast computing machines. A variable dimensioned digital model was constructed for the Shadnagar granite basin using SPECTRUM-7 micro computer to integrate various hydrogeological characteristics and for their quantitative evaluation. The basin has an areal extent of 437 sq km and is demarcated with clear water divides in all directions. Transmissivity, recharge and discharge at each cell of the basin area were estimated by trial and error simulation of the hydrogeological phenomenon under steady state condition. Dynamic simulation at representative nodes facilitated the estimation of storage coefficient. The capability of the constructed model was established by the conformance of the simulated hydrographs with the actual behaviour of the ground water system. The entire studies ammended the earlier arrived estimates of various input/output hydrogeological parameters and evolved a methodology for efficient processing of aquifer simulation data     

Hydrogeologic assessment of escalating groundwater exploitation in the Indus Basin, Pakistan

Groundwater development has contributed significantly to food security and reduction in poverty in Pakistan. Due to rapid population growth there has been a dramatic increase in the intensity of groundwater exploitation leading to declining water tables and deteriorating groundwater quality. In such prevailing conditions, the hydrogeological appraisal of escalating groundwater exploitation has become of paramount importance. Keeping this in view, a surface water–groundwater quantity and quality model was developed to assess future groundwater trends in the Rechna Doab (RD), a sub-catchment of the Indus River Basin. Scenario analysis shows that if dry conditions persist, there will be an overall decline in groundwater levels of around 10 m for the whole of RD during the next 25 years. The lower parts of RD with limited surface water supplies will undergo the highest decline in groundwater levels (10 to 20 m), which will make groundwater pumping very expensive for farmers. There is a high risk of groundwater salinization due to vertical upconing and lateral movement of highly saline groundwater into the fresh shallow aquifers in the upper parts of RD. If groundwater pumping is allowed to increase at the current rate, there will be an overall decline in groundwater salinity for the lower and middle parts of RD because of enhanced river leakage.     

Olive tree phenology and climate variations in the Mediterranean area over the last two decades

The flowering characteristics of plant species of economic interest and the influence of climate on them are of great importance considering the implications for fruit setting and the final harvest: Olive is one of the typical species of the Mediterranean habitat. We have investigated the timing of olive full flowering during the anthesis period and flowering intensity over a period of 20 years (1990–2009), in three major cultivation areas of the Mediterranean basin: Italy, Spain and Tunisia. The importance of these characteristics from a bioclimatic point of view is considered. The biological behaviour was studied to determine its main relationships with temperature and water availability, considering also the different sub-periods and the bio-climatic variations during the study period. The flowering dates and pollen emissions show different behaviours for the Spanish monitoring area in comparison with the other two olive cultivation areas. In the Italian and Tunisian areas, the flowering period over the last decade has become earlier by about 5 and 7 days, respectively, in comparison to the previous decade. Moreover, pollen emissions have decreased in Perugia (Italy) and Zarzis (Tunisia) over the period of 2000–2009, while in Cordoba (Spain), they showed their highest values from 2005 to 2009. The climate analysis has shown an increase in temperature, which results in an increase in the growing degree days for the growth of the olive flower structures, particularly in the more northern areas monitored. Although the olive tree is a parsimonious water consumer that is well adapted to xeric conditions, the increase in the potential evapotranspiration index over the last decade in the Italian and Tunisian olive areas might create problems for olive groves without irrigation, with a negative influence on the flowering intensity. Overall, in all of these Mediterranean monitoring areas, the summer water deficit is an increasingly more important parameter in comparison to the winter parameters, which confirms that the winter period is not as limiting as the summer period for olive tree cultivation in these Mediterranean areas.     

Characteristics and implication of clay minerals in the northern and southern parts of the Chelung-pu fault, Taiwan

In this study, we report the characteristics of clay minerals present in the Chelung-pu fault in Taiwan. In the 1999 Chi-Chi earthquake, different slip motions were recorded along the Chelung-pu fault in the northern and southern parts of the fault. The characteristics of clay minerals present in the fault zones can be attributed to the differences in motion. We analyzed the shallow drill core samples obtained from the northern and southern sites penetrating the fault. The clay minerals identified in most of the samples from both the sites are smectite, illite, and chlorite. There are illite–smectite mixed layers with a high illite content and no chlorite–smectite mixed layer. In some samples, no smectite is detected. We also examined the iron content and symmetry of iron and magnesium in the silicate and hydroxide layers in chlorite. At the northern site, the total iron content in chlorite of gouge is larger than that of the host rocks. On the other hand, at the southern site, the total iron content varies widely. It is hypothesized that the smectite consumption and differences in the characteristics of chlorite may be controlled by the differences in the lithology, fluid chemistry, fluid temperature, or fault activities (heating or breakage) between the northern and southern sites.     

Sulphur-containing compounds in sulphur-rich crude oils from hypersaline lake sediments and their geochemical implications

Three sulphur-rich commercial crude oils have been studied, which contain sulphur as high as up to 4–12%. These samples were collected from Tertiary hypersaline lake sediments of the Jianghan Basin, Hubei Province at different depths, but above the oil generation threshold (2200m). FPD-GC and GC-MS data show that aromatic fractions of the crude oils are composed of different homologues of sulphur-containing compounds, including long-chain normal alkyl-thiophenes and-thiolanes, long-chain isoprenoid-thiophenes and -thiolanes, and benzothiophenes. It is worth noting that the distribution patterns of long-chain alkyl-thiophenes and -thiolanes from two shallow-seated crude oils are quite similar to those of normal alkanes showing marked even-odd predominance. It seems that the even-odd predominance of sulphur-containing compounds decreases with increasing burial depth of the crude oils. The major component of aliphatic fraction is phytane, and similarly the major peaks of aromatic fractions also represent C₂₀ isoprenoid thiophenes. Some preliminary conclusions have been drawn from the above discussion: (1) Abundant sulphur-containing compounds may be used as an indicator of low mature or immature crude oils produced from hypersaline lake sediments; (2) Sulphur-containing compounds are considered to be early diagenetic products of reactions between elemental sulphur or sulfides and alkanes or their precursors (phytols, fatty acids, alcohols, etc.), or of bacterial activities, but not direct inputs of organisms.     

Natural conditions and problems of their complex utilization in the German Democratic Republic

While the natural structures of the GDR territory influenced by geological features and relief formation show a north-south sequence, variations in climate belong to a more northwest-southeast directed differentiation by maritime to continental features. Already since the Middle Ages the natural conditions of this territory have been utilized by man, at present many socially necessary functions of natural regions require rational and effective solutions for the complex utilization of nature and its resources. In order to support decisionmakers by scientific foundations for the solution of these problems, Physical Geography is concerned chiefly with three tasks: 1. Determination of the suitability and carrying capacity with regard to certain requirements of society (landscape survey). 2. Analysis of the functioning of landscape systems by the investigation of natural processes and technogene impacts on them by different forms of use. 3. Elaboration of scientific foundations in order to render possible a rational utilization and effective forms of control of natural and technogene determined landscape processes.     

Sperm motility in the Pacific oyster (Crassostrea gigas) is affected by nonylphenol

Nonylphenol, a widespread aquatic pollutant with endocrine-disrupting potential has been found to affect sperm motility in the Pacific oyster, Crassostrea gigas (Thunberg). This marine invertebrate, a global aquaculture species, was exposed to nonylphenol at concentrations of 1 and 100 μg l⁻¹ for a duration of 72 h during the period of gametogenesis. Growth was monitored at regular intervals until sexual maturity when sperm motility was assessed. The growth rate of C. gigas remained unaffected by exposure to nonylphenol during gametogenesis. However, the number of individuals with motile sperm was significantly reduced.