382 research outputs found

    Source characteristics of a moderate earthquake (M 4.9)using empirical Green ’s function technique

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    The rupture process of a moderate earthquake (M 4.9)on 28th January 1999 was analyzed using velocity records at local distances less than 80 km.The characterization of the rupture process was obtained from studying aftershocks distribution,azimuthal variations of Relative Source Time Functions (RSTFs),and a set of spatio-temporal slip models.RSTFs were retrieved by deconvolution of small aftershock records from those of the mainshock.In addition,velocity P -wave records of the respective event were inverted to recover slip distribution on the fault plane using the records of aftershocks as Empirical Green Functions (EGFs).The waveform inversion was adopted using three EGFs.In the inversion,the rupture propagation velocity was fixed and assumed to be eight-tenths of the local shear wave velocity.The total seismic moment was estimated to range from 0.011 E +18 Nm (Mw =4.6) to 0.017 E +18 Nm (Mw =4.8).The hypocentral distribution of the aftershocks,azimuthal variations of RSTFs, and the set of slip distribution models were exhibited bilateral rupture propagation along the strike and dip of the fault plane.The presence of two to three high slip patches on the fault plane suggested that a complex rupture pattern is detectable for a moderate size earthquake.However,the so-called nucleation phase was invisible in the present analysis

    Mitigation Measures for Gaza Coastal Erosion

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    Coastal erosion is an ongoing hazard affecting Gaza beach, but is worsening due to a wide range of human activities such as the construction of Gaza fishing harbor in 1994-1998. The net annual alongshore sediment transport is about 190×103 m3, but can vary significantly depending on the severity of winter storms. According to the observed wave heights and directions, the net waves are cross-shore, therefore vast quantities of sediments may transfer to deep sea. The main objective of this study is to mitigate the erosion problem of Gaza coast. Change detection analysis was used to compute the spatial and temporal change of Gaza shoreline between 1972 and 2010. The results show negative rates in general, which means that the erosion was the predominant process. Gaza fishing harbor caused a serious damage to the Beach Camp shoreline. Consequently, several mitigation measures were considered in this study, which are: relocation of Gaza fishing harbor to offshore, groins, detached breakwaters, wide-crested submerged breakwaters and beach nourishment. Several numerical model tests associated with coastal structures are conducted to investigate the influence on morphodynamics. The results show that the relocation of the harbor is the best alternative to stop trapping of the sediments. If for any reason the relocation was not carried out, the wide-crested submerged breakwater alternative is an effective structure for preventing sandy beach erosion. The artificial reef type of submerged breakwaters with beach nourishment is recommended for Gaza beach, because it is an environmentally friendly and improving the ecosystem of marine life

    Risk Perception, Self-Efficacy, Trust in Government, and the Moderating Role of Perceived Social Media Content During the COVID-19 Pandemic

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    Received 5 July 2020. Accepted 22 February 2021. Published online 19 April 2021.The public’s actions will likely have a significant effect on the course of the novel coronavirus (COVID-19) pandemic. Human behavior is conditioned and shaped by information and people’s perceptions. This study investigated the impact of risk perception on trust in government and self-efficacy. It examined whether the use of social media helped people adopt preventive actions during the pandemic. To test this hypothesis, the researchers gathered data from 512 individuals (students and academics) based in Malaysia during the COVID-19 pandemic. Our results suggested that risk perception had a significant effect on trust in government and self-efficacy. Moreover, these correlations were stronger when social media was used as a source for gathering information on COVID-19. In some cases, it even helped users avoid exposure to the virus. This study assessed the relationship between risk perception and the awareness gained from using social media during the pandemic and highlighted how social media usage influences trust in government and self-efficacy

    Association between different methods of assessing blood pressure variability and incident cardiovascular disease, cardiovascular mortality and all-cause mortality : a systematic review

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    Dr Smith is supported by the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (BRC). The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health. Dr Choon-Hian Goh is supported by the University of Malaya Post Doctoral Research Fellowship scheme. No funding was received to undertake the conduct of this study.Peer reviewedPostprin

    Simulation of Single and Twin Impinging Jets in Cross-flow of VTOL Aircrafts (Review)

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    When operating near the ground beneath a Vertical/Short Take-Off and Landing (VSTOL) aircraft a complex turbulent 3D flow is generated. This flow field can be represented by the configuration of twin impinging jets in a cross-flow. Studying these jets is a significant parameter for the design of VTOL aircraft. This flowfield during very low speed or hover flight operations is very complex and time dependent. An important number of experimental researches and simulations have been carried out to be able to understand much better these flows related with powered lift vehicles. Computational Fluid Dynamics (CFD) approach will be used in this paper work for simulation purposes of a single and twin impinging jet through and without crossflow

    Past and future impacts of urbanisation on land surface temperature in Greater Cairo over a 45 year period

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    Rapid and unplanned urbanisation can lead to altered local climate by increasing land surface temperature (LST), particularly in summer months. This study investigates the Urban Heat Island (UHI) in Greater Cairo, Egypt, using remote sensing techniques to estimate LST of summer months over 45 years (1986, 2000, 2017, and predicted year 2030). The research objectives and steps were, 1- mapped land use/ land cover (LULC), 2- conducted spatiotemporal analysis of LST, with a comparison of change in LST across different land cover types, 3- predicted future LST for 2030, and 4- examined this temporal change for a hot-spot area (ring road) and a cool-spot area (the River Nile). The results showed that urban areas have increased over the last 30 years by 179.9 km2 (13 %), while agriculture areas decreased by 148 km2 (12 %) and water bodies decreased by 6 km2 (0.5 %). The mean LST over Greater Cairo increased over time, from 31.3 °C (1986) to 36.0 °C (2017) and is predicted to reach 37.9 °C in 2030. While a notable rise of mean LST in the Cairo ring road buffer zone (88 km2), where it was 31.1 °C (1986), and 37 °C (2017) due to the triple increase of urban areas on account of agriculture areas, and the LST it may reach 38.9 °C by 2030. The mean LST increased slightly more in urban hot-spot areas than in cooler cultivated areas. UHI may induce a modification in the local climate that can negatively affect agricultural land, and human thermal comfort and unfortunately lead to a less sustainable environment
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