Settlement in Sands Due to Cyclic Loading

Stress controlled undrained cyclic triaxial tests have been conducted on undisturbed sandy and silty soil samples obtained by special sampler in order to minimize the effect of disturbance. The influence of fines content on liquefaction - induced volumetric strains have been studied. The results indicate that cyclic mobility of sands is affected by non – plastic fines content. As fines content increase, cyclic shear strength decreases. Volumetric strain is influenced by fines content as well as shear strain and cyclic stress. At large shear strains amplitudes, an increase in percentage of fines causes more volumetric strains. Volumetric strains of silt samples are affected by cyclic shear stress more than sands

Determination of shallow S-wave attenuation by down-hole waveform deconvolution: a case study in Istanbul (Turkey)

The estimation of shear-wave velocity and attenuation in near-surface geology is of primary importance in engineering seismology. In fact, their knowledge is essential for site response studies when preparing improved seismic hazard scenarios. In this study, we propose two approaches for estimating the average shear-wave quality factor Qs by using recordings of a vertical array of accelerometers. The methods are mainly based on the deconvolution of the wavefield recorded in a borehole with that recorded at the surface. The first method requires the Fourier transform of the deconvolved wavefield to be fitted with a theoretical transfer function valid for the vertical or nearly vertical (in the case at hand up to 30° incidence angle) propagation of S-waves. The second method is based on the spectral fitting of the Fourier transform of only the acausal part of the deconvolved wavefield with a theoretical transfer function. Both methods can be applied without any prior knowledge of the subsoil structure (since they are based on empirical data analysis) and do not require a precise knowledge of the azimuthal orientation of the sensors in the boreholes (which is seldom available). First, we describe the theoretical framework of the proposed methodologies for Qs estimation, which are based on the assumption that the structure in the borehole is weakly heterogeneous in the vertical direction (that is, no large impedance contrast exists between the borehole sensor and the surface). Second, by using synthetic accelerograms, we verify that in a realistic subsoil structure, the assumption of vertical homogeneity can hold and we investigate the robustness and the suitability of the proposed methods. Finally, only the method that was shown to provide the more stable results, based on fitting the borehole-to-surface spectral ratio with a theoretical function, is applied to earthquakes signals recorded by a vertical array of accelerometers installed in Ataköy (western Istanbul). Results show that using borehole data provides a fair and robust estimate of an average Qs (of about 30, 46 and 99 for the 0-50, 0-70, 0-140 m depth ranges, respectively), that can be used for numerical simulations of ground motion

Struktur Komunitas Padang Lamun di Perairan Kepulauan Waisai Kabupaten Raja Ampat Papua Barat

The research about Community structure of seagrass was conducted in the waters of Waisai, South Waigeo District, Raja Ampat, West Papua. The aim of this study was to determine the community structure of seagrass beds found in the waters of the Waisai archipelago, Raja Ampat, West Papua using quadrant transect method. Data of community structure were obtained at 3 stations that were station I in the countryside of Waisai (Post AL), station II in the Resort Waiwo (Waiwo Dive Center) and Station III in Saporkren village near residential areas. The results of this study discovered seven species of seagrass; Enhalus acoroides, Halophila decipiens, H. ovalis, Thalassia hemprichii, Cymodocea rotundata, Halodule pinifolia, Syringodium isoetifolium in all stations. Cymodocea rotundata had the highest importance value index (IV) which amounted to 79.22%, 161.15% and 134.68% in each station, respectively. While Syringodium isoetifolium had the lowest importance value index, respectively 00,00%, 6.91% and 7.80% in each station. Seagrass of Waisai waters had clumped distribution patterns. The seagrass Cymodocea rotundata is the most dominant seagrass species and influential in the community and the results of environmental parameters, pH, temperature, salinity, substrate, measured in research location are still feasible and great for the growth of seagrass

Human resources: the Cinderella of health sector reform in Latin America

Human resources are the most important assets of any health system, and health workforce problems have for decades limited the efficiency and quality of Latin America health systems. World Bank-led reforms aimed at increasing equity, efficiency, quality of care and user satisfaction did not attempt to resolve the human resources problems that had been identified in multiple health sector assessments. However, the two most important reform policies – decentralization and privatization – have had a negative impact on the conditions of employment and prompted opposition from organized professionals and unions. In several countries of the region, the workforce became the most important obstacle to successful reform. This article is based on fieldwork and a review of the literature. It discusses the reasons that led health workers to oppose reform; the institutional and legal constraints to implementing reform as originally designed; the mismatch between the types of personnel needed for reform and the availability of professionals; the deficiencies of the reform implementation process; and the regulatory weaknesses of the region. The discussion presents workforce strategies that the reforms could have included to achieve the intended goals, and the need to take into account the values and political realities of the countries. The authors suggest that autochthonous solutions are more likely to succeed than solutions imported from the outside

A Planar CPW Fed Antenna with Modified Ground for UWB

In this paper a U-Shaped Coplanar waveguide fed antenna with modified ground plane structure for WIMAX and WLAN applications is presented. The antenna is resonating at different frequencies 3.55/8.2/10 GHz which is cover 3.1GHz to 10.6 GHz Ultra Wide Band range.Antenna has simple planer structure of 23x16x1.6 mm3 using FR4 epoxy substrate dielectric constant 4.4 and loss tangent of 0.002 with a slot on ground plane. The proposed antenna achieved return loss -10 dB and it reached around -37 dB which covers the bandwidth specification of WIMAX and WLAN. The antenna is simulated using simulation tool Mentor GraphicsIE3D electromagnetic solver which is based on method of moment.

The variation of pore pressure related with failure in fine-grained soils under uniform cyclic loadings

GeoCongress 2008: Characterization, Monitoring, and Modeling of GeoSystems -- 9 March 2008 through 12 March 2008 -- New Orleans, LA -- 76250This paper discusses pore- water pressure and failure in fine-grained soils and the influences of some factors under cyclic loading. A systematic study was conducted on pore-water pressure development during cyclic failure of low - to -medium plasticity clays. A series of cyclic triaxial and cyclic torsional tests were performed on undisturbed samples taken below the water table from various sites in Turkey. Consolidation tests were conducted to estimate preconsolidation pressures for each specimen. Tests were conducted under isotropic conditions in both test systems. The loadings were stopped at a prescribed strain level of ±2.5-3% assumed as failure. Pore-pressure accumulation during the tests was observed and pore-pressure values at the time of failure were analyzed with respect to different soil parameters. In addition to the other factors such as cyclic shear stress and cyclic strain amplitude, pore pressure-accumulation varies significantly with the mineralogy of the soil sample. Copyright ASCE 2008