[en] Given an elementary simple-minded collection in the derived category of a non-positive dg algebra with finite-dimensional total cohomology, we construct a silting object via Koszul duality.

[en] Thorium activity concentrations were measured in seven marine sediment cores taken from Sabah-Sarawak coast on 2004 by using a gravity box corer. Collected sediments were generally homogenous mud which contained much more mixture of silt and clay compared to sand and relatively low content of organic carbon (i.e. less than 5% at all sampling stations). The results found that activity concentrations of ²³⁰Th, ²³²Th and ratios of ²³⁰Th/²³²Th were ranged from 6.5-20.4 Bq/kg dry wt., 6.8-27.8 Bq/kg dry wt. and 0.69-0.92, respectively. It seem that, ²³²Th activity concentrations are slightly higher than ²³⁰Th at all sampling stations and both radionuclides were generally high at Sabah compared to Sarawak coastal waters. ²³⁰Th activity concentrations in sediment core appear to be correlated with the activity concentrations of ²³²Th at some sampling station. These indicating both radionuclides were supplied from the same of environment and source origin of detrital from terrestrial and shallower water. The low ²³⁰Th/²³²Th activity ratio which is less than unity suggesting that ²³²Th was actively and rapidly regenerated compared to ²³⁰Th from ²³⁴U. It also can be attributed to less efficiently scavenge of ²³⁰Th onto particles prior deposited at the marine sediment bed. (author)

[en] The radioactive tracers, modern elements which make possible infinity of studies, are nowadays one of the main tools in the human activity. The radioisotopes, are used in medicine, industry, special programs, etc. This project is about the use of radioactive tracers in the study of the movement of solid material in the bottom of the rivers. This study is important, because it allows to make conclusions on the characteristics of material transport in the bottom, and from there, to establish certain deposit areas or the thickness of the layer of transport. The general principle of the method is the immersion or launching, in a previously established place, of a radioactive material whose characteristics are identical to those of the natural silt of the area in study, followed by an accompaniment to know the migration of this silt by means of a radiation detection equipment. Later on the traditional methods based on empiric formulas will be compared, to confront them with this method and to determine the reliability in the process

[en] There The problems facing the area of Kuala Kemaman are siltation and erosion at shoreline. The objectives of study are to assess the best alignment of the groyne alignment, to ascertain the most stable shoreline regime and to investigate structural measures to overcome the erosion. The scope of study are data collection, wave analysis, hydrodynamic simulation and sediment transport simulation. Numerical models MIKE 21 are used - MIKE 21 NSW, for wind-wave model, which describes the growth, decay and transformation of wind-generated waves and swell in nearshore areas. The study takes into account effects of refraction and shoaling due to varying depth, energy dissipation due to bottom friction and wave breaking, MIKE 21 HD - modelling system for 2D free-surface flow which to stimulate the hydraulics phenomena in estuaries, coastal areas and seas. Predicted tidal elevation and waves (radiation stresses) are considered into study while wind is not considered. MIKE 21 ST - the system that calculates the rates of non-cohesive (sand) sediment transport for both pure content and combined waves and current situation

[en] To study on relationship between dynamic shear modulus and damping ratio with shear strain, a new dynamic-triaxial test is performed on sandy silt in Beijing area. The testing data of the dynamic-shear modulus are compared with the existing statistical data in Beijing area and the statistical curve to prove the rationality of the test results. Comparsion presents a good agreement. (paper)

[en] Radioisotopes can be applied to hydrological studies in two principal ways: as a tracer to identify water, or as an age measuring device. Applications of each method are discussed in the paper. Other applications such as the possibility of using sand labelled with radioisotopes for measuring of transport of silt and sand has been investigated

[en] Dating by radiation damage methods of eolian and fluviatile sediments preferentially deposited during glacial periods is meanwhile a routine. Automated devices allow a high throughput of TL/OSL (thermoluminescence, optically stimulated luminescence) analyses while the most time-consuming work remains the separation of pure mineral fractions, their chemical and physical treatment, the calibrated radiation and last but not least the evaluation and interpretation of raw results in order to get absolute dates. Beside many widely and continuously studied basic physical phenomena, fundamental questions are not yet satisfactorily answered. For an example the influence of palaeohydrological changes to the accuracy of the absolute dates. One of the reasons may be the limited precision of TL and OSL dates. A recently introduced technique to date single-aliquots may overcome at least some of these problems. (author)

[en] Low plasticity sand-silt mixtures are very common in Italy either in natural depositional environment or in man-made earth-fill, hence the knowledge of their behavior is a crucial aspect in many practical applications. Due to higher compressibility features, significant strains and strength loss may be triggered by earthquakes. The results of a laboratory-based investigation undertaken on undisturbed samples of low plasticity silty-sandy soils recovered from a bank stretch after the 2012 Emilia Romagna earthquake in Italy, when serious damages and widespread liquefaction events were observed, are herein presented. Special emphasis was given to susceptibility to liquefaction and pore water pressure response in presence of an initial static shear stress. As part of the present work, the results of undrained cyclic simple shear (CSS) tests carried out on reconstituted specimens of sand-fines mixtures, covering a range of non plastic fines contents from 0% to 40%, were used for predicting undrained cyclic resistance through the concept of equivalent granular void ratio, e^*. The conceptual framework based on e^* appears appropriate for streamlining the effect of fines on cyclic liquefaction resistance of these intermediate soils, provided that fines content is less than a limiting value. Since an important stage in the assessment of liquefaction potential is to predict excess pore water pressure during cyclic loading, the results of CSS tests were also utilized for analysing pore water pressure generation models of silty sands over a wide range of fines contents. (paper)

[en] Highlights: • Seasonal changes of macrofaunal characteristics in a semi-enclosed bay was studied. • A total of 251 species were found with polychaetes the most dominant group. • A slight increase trend was found for macrofauna characteristics in the past decades. • This study can provide a useful baseline for macrofaunal study in semi-enclosed bays. Characteristics of macrofaunal assemblages and their relationships with environmental factors in a semi-enclosed bay were studied seasonally in China. A total of 251 species were identified, including polychaetes (104 species), crustaceans (73 species), mollusks (51 species), and other phyla (23 species). Mean values of macrofaunal abundance were 1210, 2483, 3209, 3600 ind./m² while those of biomass were 56.88, 176.15, 136.28, 265.55 g/m², respectively. Ranges of species richness index, evenness index, Shannon-Wiener index were 1.54–8.16, 0.17–0.90, 0.69–4.78, respectively. The diversity indices were affected by bottom water salinity and pH. BIOENV analysis showed that water depth, phaeophorbide, and silt-clay proportion had important impacts on macrofaunal assemblages while abundance and biomass were affected by bottom water temperature, salinity, and water depth. Compared with historical data, macrofaunal species number, abundance and biomass showed a slight increasing trend, which may be due to the water quality improvement of this bay.

[en] Rust Federal Services, Inc.'s Clemson Technical Center (CTC) has investigated the remediation of several radioactive-contaminated soils, from various DOE-FUSRAP sites, via soil washing/chemical extraction of the radioactive contaminants. The second phase of this work, which is the subject of this presentation, focused on chemical extraction via selective dissolution of radioactive contaminants. In those instances where simple physical separation processes are not practicable, e.g., when there are relatively high proportions of silt and/or clay particles, chemical extraction and the selective dissolution of target contaminants is required. Soil-decontamination processes frequently employ chelating agents which are meant to selectively enhance the dissolution of target contaminants while minimizing the dissolution of benign soil constituents. This paper will present the dissolution kinetics results from the bench-scale soil-decontamination studies