275 research outputs found
Stable Isotope Composition of Cyclone Mekunu Rainfall, Southern Oman
Cyclone Mekunu hit the southern Arabian Peninsula in late May 2018 and brought rainfall amounts that accounted for up to 6 times the mean annual precipitation. Coming from the Arabian Sea, a quite underdocumented region with regard to cyclones, the storm eye crossed the Omani coast approximately 80 km east of the border to Yemen. Using automatic samplers, rainfall samples were collected during the event at three locations along a transect almost parallel to the storm track. The stable isotope analyses show a wide range of δ values, with minimum and maximum values of −17.01‰ δ18O and −1.77‰ δ18O and −122.2‰ δ2H and −1.6‰ δ2H. On average, rainfall becomes isotopically lighter with elevation, but rather irregularly. In view of high wind speeds probably precluding a gradual rainout of ascending air masses, a “pseudo elevation effect” seems likely. Our measurements expand the known δ value range of local cyclones by about 6‰ for δ18O and by nearly 50‰ for δ2H. The isotopic composition of the annual Indian Summer Monsoon shows values of −0.93‰ δ18O to 2.21‰ δ18O and −2.1‰ δ2H to 23.7‰ δ2H. Thus, there is a clear difference in the dual isotope signatures of the two precipitation systems in the area. Our findings enable an assessment of the impact of cyclones on the hydro(geo)logical system. For the arid Najd area, we demonstrate that the isotopic signatures of groundwater samples fall between those of cyclone and (paleo)monsoon precipitation, suggesting that several rainfall types may have contributed to replenishment
Design of Multistep Aging Treatments of 2099 (C458) Al-Li Alloy
Multistep artificial aging treatments coupled with various natural aging times for aluminum lithium 2099 alloy (previously called C458) are discussed to obtain mechanical tensile properties in the T6 condition that match those in the T861 condition, having a yield strength in the range of 414-490 MPa (60-71 ksi), an ultimate strength in the range of 496-538 MPa (72-78 ksi), and 10-13% elongation. Yield and ultimate tensile strengths from 90-100% of the strength of the as-received material (in the T861 condition) were obtained. The highest tensile strengths were consistently obtained with two-step, low-to-high temperature artificial aging treatments consisting of a first step at 120 degrees C (248 degrees F) for 12-24 h followed by a second step between 165 and 180 degrees C (329-356 degrees F) for 48-100 h. These T6-type heat treatments produced average yield and ultimate strengths in the longitudinal direction in the range of 428-472 MPa (62.1-68.5 ksi) and 487-523 MPa (70.6-75.9 ksi), respectively, as well as lower yield strength anisotropy when compared with the as-received material in the T861 condition
The impact of Gaza fishing harbour on the Mediterranean coast of Gaza
The Mediterranean coast of Gaza strip, which is covered about 40 km in length, is rich by coastal resources. The development that occurred along the coastal lines has led to the host of problems such as increased erosion, siltation, loss of coastal resources and the destruction of the fragile marine habitats. In order to conserve the depleting coastal resources, the changes due to development and associated activities must be monitored. Studying the temporal pattern of shoreline change is considered one of the most effective means of monitoring the cumulative effects of different activities. An attempt was made to study the impact of Gaza harbour on shoreline displacement along 6 km. This paper was intended to detect changes of coastal area in Gaza city to provide future database in coastal management studies. The analysis was carried out using image processing technique (ERDAS) and Geographical Information System platform. The variation during 38 years in the shoreline along the Gaza coast was determined by analyzing MSS, TM and ETM Landsat images from 1972 to 2010. The analyses identified the erosion and accretion patterns along the coast. The shoreline was advanced south of the Gaza fishing harbor, where the wave-induced littoral transport was halted by southern breakwater and the annual beach growth rate was 15,900 m 2. On the downdrift side of the harbor, the shoreline was retreating and beaches erode at an annual rate of-14,000 m 2. This study was emphasized that the coastal band is considered as a critical area, it is therefore necessary to monitor coastal zone changes because of the importance of environmental
The Effects of Retrogression and Reaging on Aluminum Alloy 2099 (C458)
The objective of this study was to investigate the feasibility of performing retrogression and reaging (RRA) heat treatments on 2099 aluminum-lithium alloy. The retrogression temperatures were 200-250 A degrees C and retrogression times were 5-60 min. Half of the samples were exposed to a salt fog environment. Interestingly, the samples exposed to salt spray had consistently higher mechanical tensile properties than those which were not exposed
The Effects of Retrogression and Reaging on Aluminum Alloy 2195
A retrogression and reaging (RRA) treatment was performed on 2195 Al-Li Alloy. The exposure times were from 5 to 60 min, and the temperatures were from 200 to 250 A degrees C. Samples that were exposed to a salt spray test had overall similar mechanical properties as compared to those that were not exposed. The percent elongation, however, was significantly deteriorated due to the salt spray exposure. The mechanical properties of the 2195 samples were compared to those of 2099 samples exposed to similar treatments in an earlier study
The Influence of ICT on the Control of Corruption: A Study Using Panel Data From ASEAN Countries
Corruption might occur in many places within the government. Information and communication technology (ICT) can be used to create a more open and transparent government enabling the control of corruption (CoC). The research presented in this paper aims to analyze the effect of ICT on CoC in open government. Using panel data of ASEAN countries over 33 years from 1984 to 2016, this study examined the data utilizing panel auto-regressive distributed lags (ARDL). The results of this study reinforce the existing literature on the positive effects of ICT on CoC. However, the assumed relationship is more complicated than often assumed. This study shows the presence of a quadratic (non-linear) inverted u-shaped relationship between the ICT development and CoC, which implies that there is no further opportunity for ICT alone to reduce corruption once a threshold is reached. ICT might even be used to facilitate corruption. Hence, ICT needs to be complemented by institutional and organizational measures and education to fight corruption. © 2021 IGI Global. All rights reserved
The influence of ICT diffusion and globalization on the quality of governance: A study using panel data from ASEAN countries
Information and Communication Technology (ICT) supports the sharing of information to improve the Quality of Governance (QoG). Many studies found a relationship between ICT diffusion and globalization and between ICT diffusion and the Quality of Governance. This study investigates the influence of both ICT diffusion and globalization in explaining the country level QoG while incorporating gross domestic product (GDP) per capita, human capital, and government expenditure in the context of the ASEAN (Association of Southeast Asian Nation) region. To this end, we used Panel Autoregressive Distributed Lags (ARDL) to analyze panel data from 1984 to 2017. In contrast to research conducted in other countries, our research shows that the impact of ICT diffusion on QoG is not significant in the ASEAN region. The findings can be explained by a lack of coherent ICT-strategy among the countries and a lack of institutional mechanisms to ensure ICT efforts’ effectiveness. However, the relationship between globalization and QoG is positive and significant. © The Author(s) 2021.Universiti Teknologi MARA, UiTM; Lixin Accounting Research InstituteWe are indebted to the Mora Scholarship 5000 Doktor Ministry of Religious Affairs of Indonesia, State Islamic University of Raden Fatah Palembang, Indonesia, Accounting Research Institute (ARI, UiTM) Malaysia in giving us the support needed for this project. We appreciate the reviews and comments made by academicians on earlier drafts of this paper. Many thanks to government agencies, organizations that participated in the project
The Impact of Gaza Fishing Harbour on the Mediterranean Coast of Gaza
The Mediterranean coast of Gaza strip, which is covered about 40 km in length, is rich by coastal resources. The development that occurred along the coastal lines has led to the host of problems such as increased erosion, siltation, loss of coastal resources and the destruction of the fragile marine habitats. In order to conserve the depleting coastal resources, the changes due to development and associated activities must be monitored. Studying the temporal pattern of shoreline change is considered one of the most effective means of monitoring the cumulative effects of different activities. An attempt was made to study the impact of Gaza harbour on shoreline displacement along 6 km. This paper was intended to detect changes of coastal area in Gaza city to provide future database in coastal management studies. The analysis was carried out using image processing technique (ERDAS) and Geographical Information System platform. The variation during 38 years in the shoreline along the Gaza coast was determined by analyzing MSS, TM and ETM Landsat images from 1972 to 2010. The analyses identified the erosion and accretion patterns along the coast. The shoreline was advanced south of the Gaza fishing harbor, where the wave-induced littoral transport was halted by southern breakwater and the annual beach growth rate was 15,900 m2. On the downdrift side of the harbor, the shoreline was retreating and beaches erode at an annual rate of -14,000 m2. This study was emphasized that the coastal band is considered as a critical area, it is therefore necessary to monitor coastal zone changes because of the importance of environmental parameter and human disturbance. In particular, the projections of future shoreline erosion and accretion rates are considered important for long-term planning and environmental assessment for a variety of projects, including the construction and tourism facilities
Mitigation Measures for Gaza Coastal Erosion
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
Effect of Cold Work on the Tensile Properties of 6061, 2024, and 7075 Al Alloys
Aluminum alloys 6061, 2024, and 7075 were heat treated to various tempers and then subjected to a range of plastic strain (stretching) in order to determine their strain limits. Tensile properties, conductivity, hardness, and grain size measurements were evaluated. The effects of the plastic strain on these properties are discussed and strain limits are suggested
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