Bias adjustment of satellite-based precipitation estimation using artificial neural networks-cloud classification system over Saudi Arabia

Precipitation is a key input variable for hydrological and climate studies. Rain gauges can provide reliable precipitation measurements at a point of observations. However, the uncertainty of rain measurements increases when a rain gauge network is sparse. Satellite-based precipitation estimations SPEs appear to be an alternative source of measurements for regions with limited rain gauges. However, the systematic bias from satellite precipitation estimation should be estimated and adjusted. In this study, a method of removing the bias from the precipitation estimation from remotely sensed information using artificial neural networks-cloud classification system (PERSIANN-CCS) over a region where the rain gauge is sparse is investigated. The method consists of monthly empirical quantile mapping of gauge and satellite measurements over several climate zones as well as inverse-weighted distance for the interpolation of gauge measurements. Seven years (2010–2016) of daily precipitation estimation from PERSIANN-CCS was used to test and adjust the bias of estimation over Saudi Arabia. The first 6 years (2010–2015) are used for calibration, while 1 year (2016) is used for validation. The results show that the mean yearly bias is reduced by 90%, and the yearly root mean square error is reduced by 68% during the validation year. The experimental results confirm that the proposed method can effectively adjust the bias of satellite-based precipitation estimations

First principles study of 2D polar heterostructures.

Recently, two-dimensional (2D) heterostructures have attracted extensive attention in nanomaterials science. They have been successfully fabricated and applied to nanotechnology in many fields, such as nanoelectronics, solar cells, sensors, energy stores, quantum information, etc. The most common heterostructures are 2D-lateral heterostructure (LH) and 2D-vertical heterostructure (VH) where each of them exhibits unique features depending on the direction of assembly, i.e., along in-plane or out-of-plane direction. Beyond the van der Waals-VH which possess of van der Waals (vdW) interaction, there are other types of heterostructures made of 2D polar materials that possess different types of chemical bonding nature, e.g., chemical bonds with less (e.g., SiC monolayer) or more (e.g., GeC and SiGe monolayers) charge transfer between atoms, forming covalent bonds with a certain ionicity. The goal of this work focused on shedding light on the physical aspects of 2D LH and VH, constructed by such polar materials (e.g., , GeC, and SiGe monolayers). This work is a theoretical study by employing Density Functional Theory to unravel the unique physical properties of such heterostructures. Because an artificial strain will be induced by the lattice mismatch in building heterostructures, the effect of strain on the electronic properties of, and monolayers was first investigated. It was found that these monolayers can tolerate strain up to 8%, and such strain can induce modifications on the physical properties. Interestingly, it was found that and monolayers undergo a direct-indirect band gap transition; while, monolayer undergoes a metal-semimetal transition, which made them attractive candidates for building heterostructures. Second, a systematic study on the aspect of 2D polar-LH of and has been conducted. It was found that the synergistic effect of the lattice mismatch induced strain, the chemical bonding nature at the interface, and quantum confinement can lead to several interesting phenomena. For instance, their electronic properties can be modulated by tuning the domain size, the chemical bonding nature, and the designing of interface. Accordingly, a lateral spontaneous p-n junction triggered by the in-plane charge transfer was detected which implies the promising applications such as visible light photocatalyst. Third, the roles of the stacking species arrangement and the interlayer interactions (including vdW and electrostatic forces) on stabilizing the structure and modulating electronic properties of 2D polar-VH of were deeply studied. It was found that, in addition to the redistribution of the in-plane net-charge transfer, a net charge redistribution also occurs between layers and leads to a polarization in the interfacial region that induces a built-in electric field and helps to reduce the recombination of photogenerated electron-hole pairs

Application of Unified Power Flow Controller to Improve the Performance of Wind Energy Conversion System

This research introduces the unified power flow controller (UPFC) as a means to improve the overall performance of wind energy conversion system (WECS) through the development of an appropriate control algorithm. Also, application of the proposed UPFC control algorithm has been extended in this research to overcome some problems associated with the internal faults associated with WECS- voltage source converter (VSC), such as miss-fire, fire-through and dc-link faults

The use of endo-vascular balloon tamponade technique for the removal of a misplaced nephrostomy tube in the inferior vena cava: A case report

AbstractIntroductionInadvertent placement of a nephrostomy tube into the inferior vena cava (IVC) is an extremely rare complication with few reported cases in the literature.Case presentationWe present a lady with obstructive uropathy in a solitary kidney in whom an attempt by the community radiologist to place a nephrostomy tube was complicated by wrong insertion into the IVC. This report illustrates how a safe non- surgical removal of this tube using an intravenous balloon tamponade technique was successfully applied.DiscussionIntravenous placement of nephrostomy catheters into the inferior vena cava is extremely rare complication. A few case reports have been published in the literature. The majority of these cases were removed in the operating room under general anesthesia. Using Intravenous balloon tamponade technique for removal has not been previously reported.ConclusionIntravenous balloon tamponade technique is effective and is a good minimally invasive alternative to surgical removal of misplaced nephrostomy tube from IVC

Corporate Social Responsibility and Corporate Performance: Does Financial Reporting Quality Matter?

This study aims to analyze the role of social responsibility in times of crisis, where the study examines whether the role of social responsibility in the corporate performance will depend on its interaction with other basic aspects of the corporate business environment. In the contemporary economic context, information environment considers important aspects of the business environment, therefore, it can be suggested that the impact of social responsibility on the company’s performance will be clearer when considering its interaction with financial reporting quality. To test this argument, data from the Saudi business environment for the year 2020 was collected to explore the relationship between social responsibility and the company’s financial performance during the Corona pandemic, and the role of the financial reporting quality in that relationship. The results were largely consistent with the general argument of the study, the results showed that social responsibility does not affect the financial performance, but the interaction between it and the financial reporting quality positively affects the financial performance of the company during the pandemic period. Therefore, financial reporting quality play a major role in the extent to which social responsibility affects performance. The results represent a motivation for the various parties in the business environment to pay attention to the general framework of the companys business aspects when analyzing performance

Application of UPFC to Improve the LVRT Capability of Wind Turbine Generator

Variable speed wind turbine generators installation has been significantly increased worldwide in the last few years. Voltage sag at the grid side may call for the disconnection of the wind turbine from the grid as under such faults it may not comply with the recent developed grid codes for wind energy conversion systems (WECS). In this paper, a Unified Power Flow Controller (UPFC) is applied to improve the low voltage ride through (LVRT) capability of doubly fed induction generator (DFIG)-based WECS during voltage sag at the grid side. Simulation is carried out using MATLAB/Simulink software. Results show that UPFC can significantly improve the LVRT capability of DFIG-based WECS and hence maintaining wind turbine connection to the grid during certain levels of voltage sag at the grid side

Design and Development of RF Structures for Linac4

Linac4 is a new 160 MeV Hâ linac proposed at CERN to replace the 50 MeV Linac2 as injector to the PS Booster, with the goal of doubling its brightness and intensity. The present design foresees after RFQ and chopping line a sequence of three accelerating structures: a Drift Tube Linac (DTL) from 3 to 40 MeV, a Cell-Coupled DTL (CCDTL) to 90 MeV and a Side Coupled Linac (SCL) up to the final energy. The DTL and CCDTL operate at 352 MHz, while in the SCL the frequency is doubled to 704 MHz. Although the injection in the PS Booster requires only a low duty cycle, the accelerating structures are designed to operate at the high duty cycle required by a possible future extension to a high-power linac driver for a neutrino facility. This paper presents the different accelerating structures, underlining the progress in the design of critical resonator elements, like post-couplers in the DTL, coupling slots in the CCDTL and bridge couplers for the SCL. Prototyping progress for the different structures is reported, including the RF design of a DTL tank prototype and results of low- and high-power tests on a CCDTL prototype