Empirical seismic vulnerability analysis for masonry buildings based on school buildings survey in Iran

School facilities in Iran, in particular masonry schools, have shown poor performance during past earthquakes and can be identified as one of the parts of the country’s infrastructure that is most vulnerable to earthquakes. Hence, in this paper a method to perform index-based damage assessment for brick masonry schools located in the province of Yazd, the central region of Iran, using a comprehensive database of school buildings, is proposed. The database was obtained from the field survey forms applied for each observed school to collect the features of and damage to the structure. The results of a vulnerability index method developed in Iran are employed as input data to obtain empirical fragility curves for the school inventory. The Macroseismic model and GNDT II level method are two empirical methods combined in this procedure. Finally, the procedure is verified using damage survey data obtained after recent earthquakes (1990 Manjil–Rudbar earthquake and 2003 Bam earthquake) that occurred in Iran.     

Nematode community structure in relation to metals in the southern of Caspian Sea

Spatial distribution and structure of nematode assemblages in coastal sediments of the southern part of the Caspian Sea were studied in relation to environmental factors. By considering metals, organic matter, Shannon diversity index(H), maturity index(MI) and trophic diversity(ITD), ecological quality status of sediment was also determined. Fifteen nematode species belonging to eleven genera were identified at the sampling sites. Average density of nematode inhabiting in sediment of the studied area was 139.78±98.91(ind. per 15.20 cm~2). According to redundancy analysis(RDA), there was high correlation between metals and some species. Based on biological indicators, the studied area had different environmental quality. Generally, chemical and biological indices showed different results while biological indices displayed similar results in more sites.     

Bottom layer anoxia in the central part of the Gulf of Trieste in the late summer of 1983

Anoxic conditions in the near-bottom layer below the pycnocline were observed in September 1983 causing mass mortality of benthic macrofauna in the central part of the Gulf of Trieste. The vertical transport of particulate organic matter and decomposition of abundant pelagic and benthic organic matter during the summer produced a low oxygen level in the near-bottom layer below the pycnocline when this layer was sufficiently close to the bottom. A high sea water temperature and vertical stability contributed to the development of anoxic conditions in September 1983 in the near-bottom layer.     

The influence of experimental sewage pollution on lagoon phytoplankton

In a sewage pollution experiment in the lagoon system at Strunjan, Yugoslavia, an artificially polluted lagoon showed significantly lower chlorophyll a biomass and cell density, and the relationship between these two variables was altered.     

Zircon U-Pb dating,mineralogy and geochemical characteristics of the gabbro and gabbro-diorite bodies,Boein–Miandasht,western Iran

ABSTRACT

The Boein–Miandasht Complex (BMC) is a part of the Sanandaj–Sirjan metamorphic basement and is cut by gabbroic to granitoid bodies. These intrusive bodies comprise gabbro, gabbro–diorite associated with fine-grained, in part porphyritic leucocratic granitoids. Zircon U–Pb dating of representative gabbro–diorite samples yielded ages of 166.4 ± 1.8 Ma and 163.5 ± 6.3 Ma (Callovian, the latest stage of the Middle Jurassic). Mineral chemistry of the gabbro–diorites shows a homogeneous composition of the main minerals, main augite to diopside clinopyroxene and plagioclase (~An_17–59). Moreover, low Al_Z/TiO₂ ratios of the clinopyroxene grains suggest that the rocks were generated in a within-plate tectonic regime. The SiO₂ contents of the gabbro-diorite rocks are between 46.36 and 55.61 wt. %, Al₂O₃ ranges from 7.57 to 17.98 wt. %. The TiO₂ contents vary from 1.18 to 3.65 wt. %, Fe₂O₃ from 7.41 to 12.95 wt. %, the MgO ranges between 3.49 and 15.75 wt. %, Na₂O from 0.65 to 5.08 wt. % and K₂O from 0.48 to 1.08 wt. %. These rocks mostly plot in the alkali-gabbro field. Compared to chondrite are characterized by enrichment of LREEs over HREE, enrichment of LIL elements (e.g. Rb, Sr and Ba) and obvious positive anomalies of Nb and Ti. Based on the chemical composition, and mineral composition, this complex was generated in an extensional tectonic regime by partial melting of the hot asthenospheric mantle which is not more consistent with previous models which have suggested for SaSZ evolution in before.     

The application of multiple linear regression method in reference evapotranspiration trend calculation

Trend analysis of reference evapotranspiration (ET₀), as a key factor in irrigation programming, has an important role in water resources management. Many parameters affect ET₀ and their variations can change its values. In this paper, the effect of temporal variation of meteorological variables including wind speed, temperature, solar radiation and saturation vapor pressure deficit on temporal variations of ET₀ was analyzed. Trend analysis of ET₀ and its more effective meteorological parameters was accomplished in 30 synoptic stations which are located in Iran using Spearman’s Rho test. The multiple linear regressions were also used to determine the relationship between ET₀ trend and the trend of its more effective parameters. Increasing and decreasing trends in ET₀ were obtained at annual and seasonal scales. Many studied stations which had decreasing trend in the annual and seasonal periods have been located in the arid climates while all stations which have been located in humid and very-humid climates, had an increasing trend in annual and seasonal periods. The trend results in studied variables showed that annual and seasonal values of wind speed, temperature and saturation vapor pressure deficit decrease however the values of solar radiation increases in most studied stations. Multiple linear regressions results demonstrated that ET₀ trend can be calculated by the trend of two more effective variables including wind speed and saturation vapor pressure deficit.     

The spatial–temporal variation of dry and wet periods in Iran based on comparing SPI and RDI indices

Drought is a natural hazard which can cause harmful effects on water resources. To monitor drought, the use of an indicator and determination of wet and dry period trend seem to have an important role in quantifying the drought analysis. In this paper, in addition to the comparison of Reconnaissance Drought Index (RDI) and Standardized Precipitation Index (SPI), based on the most appropriate probability distribution function, it was tried to examine the trends of dry and wet periods based on the mentioned indices. Accordingly, the meteorological data of 30 synoptic stations in Iran (1960–2014) was used and the trend was analyzed using the Mann–Kendall test by eliminating the effect of any significant autocorrelation coefficients at 95% confidence level (modified Mann–Kendall). Comparing results between the time series of RDI and SPI drought indices based on statistical indicators (RMSE?<?0.434, R²?>?0.819 and T-statistic?<?0.419) in all studied stations revealed that the behavior of the two indices was roughly the same and the difference between them was not significant. The trend analysis results of RDI and SPI indices based on modified Mann–Kendall test showed that the variation of dry and wet periods was decreasing in most of the studied stations (five cases were significant). In addition, the results of the trend line slope of dry and wet periods related to the drought indices in the studied area indicated that the slope was negative for SPI and RDI indices in 70% and 50% of stations, respectively.     

Stratus–Fog Formation and Dissipation: A 6-Day Case Study

A suite of active and passive remote sensing instruments and in-situ sensors deployed at the SIRTA Observatory (Instrumented Site for Atmospheric Remote Sensing Research), near Paris, France, for a period of six months (October 2006–March 2007) document simultaneously radiative, microphysical and dynamic processes driving the continental-fog life cycle. The study focuses on a 6-day period between 23 and 29 December 2006 characterized by several stratus-cloud lowering and lifting events and almost 18 h of visibility below 1 km. Conceptual models and different possible scenarios are presented here to explain the formation, the development and the dissipation phases of three major stratus–fog events and to quantify the impact of each driving process. For example, slowly evolving large-scale conditions characterized by a slow continuous cloud-base lowering, followed by a rapid transient period conductive to fog formation and dissipation, are observed for cases 1 and 3. During this stable period, continuous cloud-top radiative cooling (≈ −160 Wm⁻²) induces a progressive and slow lowering of the cloud base: larger droplets at cloud top (cloud reflectivity approximately equals to −20 dBZ) induce slow droplet fall to and beyond cloud base (Doppler velocity ≈ −0.1 ms⁻¹), cooling the sub-cloud layer by evaporation and lowering the saturation level to 100 m (case 1) or to the surface (cases 2 and 3). Suddenly, a significant increase in Doppler velocity magnitude ≈ −0.6 ms⁻¹ and of turbulent kinetic energy dissipation rate around 10⁻³ m²s⁻³ occurs at cloud base (case 1). These larger cloud droplets reach the surface leading to fog formation over 1.5 h. The Doppler velocity continues to increase over the entire cloud depth with a maximum value of around −1 ms⁻¹ due to the collection of fog droplets by the drizzle drops with high collection efficiency. As particles become larger, they fall to the ground and lead to fog dissipation. Hence, falling particles play a major role in both the formation and also in the dissipation of the fog. These roles co-exist and the balance is driven by the characteristics of the falling particles, such as the concentration of drizzle drops, the size distribution of drizzle drops compared to fog droplets, Doppler velocity and thermodynamic state close to the surface.     

Estimating width of the stable channels using multivariable mathematical models

Predicting behavior and the geometry of the channels and alluvial rivers in which the erosion and sediment transport are in equilibrium is one of the most important topics in river engineering. Various researchers have proposed empirical equations to estimate stable river width (W). In this research, empirical equations were examined and tested with a comprehensive available data set consisting of 1644 points collected from 29 stable rivers in various parts of the world. The data set covers a wide range of flow conditions, river geometry, and bed sediments. This data set is classified in two groups (W < 600 m and W ≥ 600 m) for presenting the new models. The new linear and nonlinear multivariable equations were fitted to these two groups, and the best models were selected by preliminary tests and diagnostic determined for each group. The determination coefficient of these models ranged from 0.87 to 0.96. The results show that the models presented in this paper are more accurate with respect to the previously presented models. In the second part, “Artificial neural networks,” perceptron was used and a new methodology for estimating stable channel width was developed. Comparison of the statistical methods presented in this paper and the results of perceptron neural network revealed preferential recent method.     

Role of Bacteria in the Carbon and Nitrogen Flow between Water-Column and Sediment in a Shallow Marine Bay (Bay of Piran, Northern Adriatic Sea)

Abstract. The interdependences between phytoplankton standing crop, bacterial biomass and the dissolved organic matter (DOM) pool in the water column were investigated and related to sediment parameters in a shallow marine bay (Bay of Piran, Northern Adriatic Sea) over an annual cycle. Bacterioplankton density varied between 1–10 × 10⁵ cells ml^-1, with lowest density observed in March corresponding to the low Chi a concentrations during this period. Generation times as determined by dialysis incubations ranged between 4h (June) and 82 h (March). Mean bacterial secondary production rates during summer were about 40 mg C m^-1 d^-1 and 5mg C m^-3.d^-1 during winter. With a short time lag, DOM concentrations followed the fluctuation in Chi a.
Sediment oxygen demand measurements revealed a mean mineralization rate of about 260 mg C m^-2 d^-1 during summer and 100–200 mg C m^-2 d^-1 in winter. Sediment bacterial density varied between 10⁸ - 10⁹ cells g (sediment dry wt)^-1 in the top 5 cm sediment layer or, in terms of biomass, 4.3 g C m^-l during summer and 0.6 g C m^-2 during winter. Highest concentrations of DOM in pore waters were measured in September, coinciding with high rates of sediment oxygen demand.