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The world is shifting toward renewable energy sources (RESs) to generate clean energy and mitigate the stress of global warming caused by CO2 emissions in recent decades. Among several RES types, large-scale photovoltaic (LSPV) plants are a promising source for meeting ambitious clean energy targets and being part of power generation. With the progress of high-power modular inverters, new opportunities have arisen to integrate them into LSPV systems connected to medium-voltage (MV) grids to obtain high efficiency and reliability, better system flexibility, and improved electrical safety compared with string or central inverters. This thesis presents and implements a new current source three-phase modular inverter (TPMI) based on a novel dual-isolated SEPIC/CUK (DISC) converter. The TPMI is designed with a single power processing stage comprised of seriesconnected DISC submodules (SMs) to deliver MV into the utility grid. It outperforms conventional high-power inverters in terms of modularity, scalability, galvanic isolation compliance, and distributed maximum power point tracking (MPPT) capabilities. The DISC converter employed as an SM in the proposed TPMI generates bipolar output (i.e., both positive and negative voltages). In addition to having step-up and step-down capabilities with a continuous input current, this converter shares an input side inductor, thereby reducing the number of components. The DISC structure, modulation method, operation, novel state-space model, and parameter design procedure are analysed in details. Then, simulation results are presented to validate the theoretical and analytical analyses of the DISC converter. The proposed TPMI inverter is subsequently integrated into the LSPV grid connection to prove its suitability for such applications. In the theoretical analysis, the advantages of TPMI structure over conventional topologies are discussed. Then, the modulation technique, and operational concept are presented, followed by a dedicat

We investigate THz communication uplink multiple access using cascaded intelligent reflecting surfaces (IRSs) assuming correlated channels. Two independent objectives to be achieved via adjusting the phases of the cascaded IRSs: 1) maximizing the received rate of a desired user under interference from the second user and 2) maximizing the sum rate of both users. The resulting optimization problems are non-convex. For the first objective, we devise a sub-optimal analytical solution by maximizing the received power of the desired user, however, this results in an over determined system. Approximate solutions using pseudo-inverse and block-based approaches are attempted. For the second objective, a loose upperbound is derived and an exhaustive search solution is utilized. We then use deep reinforcement learning (DRL) to solve both objectives. Results reveal the suitability of DRL for such complex configurations. For the first objective, the DRL-based solution is superior to the sub-optimal mathematical methods, while for the second objective, it produces sum rates almost close to the exhaustive search. Further, the results reveal that as the correlation-coefficient increases, the sum rate of DRL increases, since it benefits from the presence of correlation in the channel to improve statistical learning., Comment: 30 Pages, 11 Figures, 2 Tables

Quickest change detection (QCD) is a fundamental problem in many applications. Given a sequence of measurements that exhibits two different distributions around a certain flipping point, the goal is to detect the change in distribution around the flipping point as quickly as possible. The QCD problem appears in many practical applications, e.g., quality control, power system line outage detection, spectrum reuse, and resource allocation and scheduling. In this paper, we focus on spectrum sensing as our application since it is a critical process for proper functionality of cognitive radio networks. Relying on the cumulative sum (CUSUM), we derive the probability of detection and the probability of false alarm of CUSUM based spectrum sensing. We show the correctness of our derivations using numerical simulations., Comment: This paper is accepted for publication in IEEE Communication Letters Jan 2020

In this paper, we present a physical-layer security scheme that exploits artificial noise (AN) to secure the downlink legitimate communications and transfer energy to nodes operating under non-cooperative non-orthogonal multiple-access (NOMA) scenario. The nodes employ a joint time-switching and power-switching scheme to maximize the harvested energy. We provide necessary analysis and derivations for the optimization parameters and find the optimized transmission parameters that maximize the minimum secrecy rate among users while meeting constraints on minimum transferred energy and outage probabilities at the nodes through an exhaustive grid-based search. Our analysis and simulations prove the feasibility of securing the communication among NOMA nodes, while transferring energy and meeting outage probability constraints., Comment: Accepted for publication in IEEE TVT (August 11, 2020)

Mohamed Ibrahem Eid,1 Mohamed Sayed Abdelhafez,1 Waleed El-refaie,2 Ahmed A El-Zayadi,1 Khaled Samir,1 Mahmoud Mohamed Abdelrazik,1 Mahmoud Thabet,1 Alaa Wageh,1 Emad Ahmed Fyala,1 Yasser Abdeldayem,1 Ahmed Badawy1 1Department of Obstetrics and Gynecology, Mansoura University, Mansoura, Egypt; 2Department of Obstetrics and Gynecology, Port Said University, Port Said, Egypt Objective: We aimed to evaluate the effect of different timing of initiation of low-molecular- weight heparin (LMWH) administration on the pregnancy outcomes in women with antiphospholipid syndrome (APS). Materials and methods: A randomized controlled study was conducted on women with obstetrical APS. All participants were randomly divided at documentation of positive pregnancy test into two groups; early initiation group in which LMWH therapy was started once positive pregnancy test was established (in the fifth week of gestation), and later initiation group in which LMWH therapy was started after sonographic confirmation of fetal cardiac pulsation (in the seventh week of gestation). In both groups, LMWH (enoxaparin) was given at a dose of 40 mg/day subcutaneously and the therapy continued until end of pregnancy. The primary outcome measure was ongoing pregnancy rate and the secondary outcome measures were fetal loss, live birth rate, preterm labor before 34 weeks of gestation, intrauterine growth restriction (IUGR), and congenital fetal malformations. Results: Ninety-four women (48 in the early initiation group and 46 in the later initiation group) were subjected to final analysis. The ongoing pregnancy rate was significantly higher in the early initiation group than in the later initiation group (81.2% vs 60.9%; P=0.040). However, both groups were similar in the incidences of fetal loss, preterm labor before 34 weeks of gestation, and IUGR, and live birth rate. No recorded congenital fetal malformations in both groups. Conclusion: Early administration of LMWH for pregnant women with obstetrical

Unmanned Aerial Vehicles (UAVs) have recently rapidly grown to facilitate a wide range of innovative applications that can fundamentally change the way cyber-physical systems (CPSs) are designed. CPSs are a modern generation of systems with synergic cooperation between computational and physical potentials that can interact with humans through several new mechanisms. The main advantages of using UAVs in CPS application is their exceptional features, including their mobility, dynamism, effortless deployment, adaptive altitude, agility, adjustability, and effective appraisal of real-world functions anytime and anywhere. Furthermore, from the technology perspective, UAVs are predicted to be a vital element of the development of advanced CPSs. Therefore, in this survey, we aim to pinpoint the most fundamental and important design challenges of multi-UAV systems for CPS applications. We highlight key and versatile aspects that span the coverage and tracking of targets and infrastructure objects, energy-efficient navigation, and image analysis using machine learning for fine-grained CPS applications. Key prototypes and testbeds are also investigated to show how these practical technologies can facilitate CPS applications. We present and propose state-of-the-art algorithms to address design challenges with both quantitative and qualitative methods and map these challenges with important CPS applications to draw insightful conclusions on the challenges of each application. Finally, we summarize potential new directions and ideas that could shape future research in these areas.

Estimating the number of sources received by an antenna array have been well known and investigated since the starting of array signal processing. Accurate estimation of such parameter is critical in many applications that involve prior knowledge of the number of received signals. Information theo- retic approaches such as Akaikes information criterion (AIC) and minimum description length (MDL) have been used extensively even though they are complex and show bad performance at some stages. In this paper, a new algorithm for estimating the number of sources is presented. This algorithm exploits the estimated eigenvalues of the auto correlation coefficient matrix rather than the auto covariance matrix, which is conventionally used, to estimate the number of sources. We propose to use either of a two simply estimated decision statistics, which are the moving increment and moving standard deviation as metric to estimate the number of sources. Then process a simple calculation of the increment or standard deviation of eigenvalues to find the number of sources at the location of the maximum value. Results showed that our proposed algorithms have a better performance in comparison to the popular and more computationally expensive AIC and MDL at low SNR values and low number of collected samples., Comment: 2015 International Wireless Communications and Mobile Computing Conference (IWCMC)

Ahmed Badawy,1 Mohamed A Sobh,2 Mohamed Ahdy,3 Mohamed Sayed Abdelhafez1 1Department of Obstetrics and Gynecology, 2Department of Internal Medicine, 3Department of Clinical Pharmacology, Mansoura University, Mansoura, Egypt Objective: Attempting in vivo healing of cyclophosphamide-induced ovarian insufficiency in a mouse model using bone marrow mesenchymal stem cells (BMMSCs).Methods: Female BALB/c white mice were used to prepare a model for premature ovarian failure by single intraperitoneal injection of cyclophosphamide (80 mg/kg). Ten mice were injected with BMMSCs and then sacrificed after 21 days for morphometric evaluation of the ovaries. Hormonal profile was evaluated while mice were being sacrificed. Another 10 mice were left for natural breeding with male mice, and 5 of these were injected with BMMSCs. Oocyte-like structures were obtained from 3 mice and were subjected to in vitro fertilization/intracytoplasmic sperm injection.Results: Morphometric analysis of the ovaries demonstrated the presence of newly formed primordial follicles. Contribution of MSCs to the formation of these follicles was proven by a labeling technique. There was a drop in estradiol and rise in follicle-stimulating hormone levels, followed by resumption of the hormonal levels to near normal 21 days after MSCs therapy. The 5 mice that were injected with MSCs became pregnant after natural breeding. Fertilization and further division was reported in 5 oocytes subjected to intracytoplasmic sperm injection, but division did not continue.Conclusion: From this proof-of-concept trial, we can say that healing of damaged ovaries after chemotherapy in mice is possible using in vivo therapy with BMMSCs. This should open the gate for a series of animal studies that test the possibility of in vitro maturation of germinal epithelium of the ovary into mature oocytes. Keywords: cyclophosphamide, stem cell, POF, ovarian insufficiency

Due to the peculiarity of wireless sensor networks (WSNs), where a group of sensors continuously transmit data to other sensors or to the fusion center, it is crucial to compress the transmitted data in order to save the consumed power, which is paramount in the case of portable devices.There exists several techniques for data compression such as discrete wavelet transform (DWT) based, which fails to achieve high compression ratio for an acceptable distortion ratio. In this paper, we explore exploiting Walsh transform with a moving average filtering (MAF) for data compression in WSNs.One application of WSN is wireless body sensor networks.We apply Walsh transform on real Electroencephalogram (EEG) data collected from patients.Furthermore, we compare our results to DWT and show the superiority of exploiting Walsh transform for data compression.We show that using MAF with Walsh transform enhances the compression ratio for up to 30% more than that achieved by DWT.

Differential-mode inverter topologies are promising for renewable energy generation since they offer advantages such as passive elements sizes reduction, having decreased power losses and reduced total cost. Single phase buck–boost differential-mode current-source inverters (DMCSIs) can deliver wider range of output voltage above or below the input dc voltage, which is necessary for high-efficiency modern renewable energy applications. Since these inverters have continuous input currents, they are suitable for maximum power point tracking (MPPT) operation of photovoltaic systems. Yet, the investigation, operation and implementation of these types of inverters have not been extensively discussed. As a drawback, the total dc side input current of a single-phase inverter consists of a dc component and an undesirable ac component. This ac component frequency is double the output voltage frequency and thus it affects MPPT resulting in reduced total efficiency. In this study, five promising DMCSIs are proposed and compared in terms of their total efficiencies, high-frequency ripple current in the dc side, total harmonic distortion, devices sizes and ratings. Moreover, the sliding mode controller's design and possible methods of eliminating the input second harmonic current are discussed. 2.5 kW bidirectional inverters are implemented to confirm the design flexibility of the proposed DMCSIs.

A palynological study of the Ordovician–Silurian boundary (Katian–Rhuddanian) succession in the Röstaånga-1 drillcore, southern Sweden, has been performed. The lithology is dominated by mudstone and graptolitic shale, with subordinate limestone, formed in the deeper marine halo of southernBaltica. The palynological assemblages are dominated by marine microfossils, mainly chitinozoans and acritarchs. Sparse but well-preserved cryptospores, including Tetrahedraletes medinensis, Tetrahedraletes grayii and Pseudodyadospora sp., were encountered in the Lindegård Formation (late Katian–early Hirnantian), with the oldest record just above the first appearance of the graptolite species Dicellograptus complanatus. This represents the earliest record of early land plant spores from Sweden and possibly also from Baltica and implies that land plants had migrated to the palaeocontinent Baltica by at least the Late Ordovician.

In the context of physical layer security, a physical layer characteristic is used as a common source of randomness to generate the secret key. Therefore an accurate estimation of this characteristic is the core for reliable secret key generation. Estimation of almost all the existing physical layer characteristic suffer dramatically at low signal to noise (SNR) levels. In this paper, we propose a novel secret key generation algorithm that is based on the estimated angle of arrival (AoA) between the two legitimate nodes. Our algorithm has an outstanding performance at very low SNR levels. Our algorithm can exploit either the Azimuth AoA to generate the secret key or both the Azimuth and Elevation angles to generate the secret key. Exploiting a second common source of randomness adds an extra degree of freedom to the performance of our algorithm. We compare the performance of our algorithm to the algorithm that uses the most commonly used characteristics of the physical layer which are channel amplitude and phase. We show that our algorithm has a very low bit mismatch rate (BMR) at very low SNR when both channel amplitude and phase based algorithm fail to achieve an acceptable BMR.

We propose an intuitive, simple and hardware friendly, yet surprisingly novel and efficient, received signal's angle of arrival (AoA) estimation scheme. Our intuitive, two-phases cross-correlation based scheme relies on a switched beam antenna array, which is used to collect an omni-directional signal using few elements of the antenna array in the first phase. In the second phase, the scheme switches the main beam of the antenna array to scan the angular region of interest. The collected signal from each beam (direction or angle) is cross correlated with the omni-directional signal. The cross-correlation coefficient will be the highest at the correct AoA and relatively negligible elsewhere. The proposed scheme simplicity stems from its low computational complexity (only cross-correlation and comparison operations are required) and its independence of the transmitted signal structure (does not require information about the transmitted signal). The proposed scheme requires a receiver with switched beam antenna array, which can be attached to a single radio frequency chain through phase shifters, hence, its hardware friendliness. The high efficiency of our system can be observed by comparing its performance with the literature's best performing MUSIC algorithm. The comparison demonstrates that our scheme outperforms the MUSIC algorithm, specially at low SNR levels. Moreover, the number of sources that can be detected using our scheme is bound by the number of switched beams, rather than the number of antenna elements in the case of the MUSIC algorithm.

A multiproxy study on sedimentary rocks spanning the Ordovician-Silurian boundary has been performed on material from the Röstånga-1 core, with the aims to improve the biostratigraphical and sedimentological framework and to interpret the depositional environment during this interval in Earth’s history. The sedimentary succession in the Röstånga-1 core is developed in the Scanian Lithofacies Belt and is considered an excellent upper Middle Ordovician-Lower Silurian reference section for southernmost Sweden. The studied succession includes the Sularp Shale, the Skagen Limestone (early middle Katian), the Mossen-Fjäcka formations, the Lindegård Mudstone and the Kallholn Formation. The results from this study, which includes sedimentological, palynological and stratigraphical investigations, add to the knowledge on the climatic changes across the Ordovician-Silurian boundary. During the time interval covered in the drill core, an intense Ordovician volcanism was climaxed by a short-lived glacial pulse which in turn led to a eustatic regression. The intense volcanism is evidenced by several K-bentonite beds in the Röstånga-1 core. This event left its signature as a development of a sequence boundary and solution structures at the top of the Skagen Limestone. The regressive phase was rapidly succeeded by a return to deeper-water conditions evident within the Mossen-Fjäcka succession, implying that the rate of glacio-eustatic regression was greater than the subsidence rate at that time in Scania. During the deglaciation phase, anoxic black shale coincides with a flooding surface at the base of the Fjäcka Shale. This possibly signifies a high palaeo-productivity and preservation. Following the Fjäcka Shale, the Lindegård Mudstone marks a sea-level highstand and a stable environment. Based on the palynological results, the succession was subdivided into three informal local palynozones. Palynozone I is of late Katian (pre-Hirnantian Ashgill) age and is characterized by the, Populärvetenskaplig sammanfattning En multiproxy-analys har utförts genom ordovicium-silurgränsen i borrkärnan Röstånga-1 från västcentrala Skåne. Målet med studien är att förbättra det biostratigrafiska och sedimentologiska ramverket, samt att tolka avsättningsmiljön under detta tidsintervall. Lagerföljden i Röstånga-1-kärnan tillhör det skånska litofaciesbältet och omfattar Sularpsskiffern, Skagenkalkstenen (tidig–mellersta Katian), Mossenskiffern, Fjäckaskiffern, Lindegårdsslamstenen och Kallholnformationen. Denna studie omfattar sedimentologiska, palynologiska och stratigrafiska undersökningar och resultaten bidrar särskilt till kunskapen om klimatförändringar i slutet av ordovicium och början av silur. Tidsintervallet som täcks i borrkärnan representerar en period av intensiv ordovicisk vulkanism och en kortlivad köldperiod som i sin tur ledde till en eustatisk havsnivåsänkning. Sistnämnda händelse avspeglas genom en sekvensgräns och upplösningsstrukturer i toppen av Skagenkalkstenen. Den regressiva fasen följdes av en återgång till djupare marina förhållanden med avsättning av Mossen- och Fjäckaskiffern. Basen av Fjäckaskiffern är en översvämningsyta och enheten som helhet domineras av svarta skiffrar som avsattes under syrefattiga förhållanden med hög produktivitet av organiskt material. Lindegårdsslamstenen avsattes under en period med relativt höga havsnivåer och reflekterar stabila sedimentationsförhållanden i bassängen. Baserat på de palynologiska resultaten, kan lagerföljden delas in i tre informella, lokala palynozoner (I–III). Palynozon I är av sen Katian (pre-Hirnantian Ashgill) ålder och kännetecknas av följande akritarktaxa: Baltisphaeridium, Buedingiisphaeridium balticum och Orthosphaeridium inflatum. Förekomsten av kryptosporer inom denna palynozon utgör de äldsta bevisen för tidiga landväxter på paleokontinenten Baltica. I den övre delen av denna palynozon förekommer omlagrade akritarker av tidig–mellanordovicisk ålder: Striatotheca, Coryphidium

Ahmed Badawy1 Abubaker Elnashar21Department of Obstetrics and Gynecology, Mansoura University, Mansoura, Egypt; 2Department of Obstetrics and Gynecology, Benha University, Benha, EgyptAbstract: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women. The clinical manifestation of PCOS varies from a mild menstrual disorder to severe disturbance of reproductive and metabolic functions. Management of women with PCOS depends on the symptoms. These could be ovulatory dysfunction-related infertility, menstrual disorders, or androgen-related symptoms. Weight loss improves the endocrine profile and increases the likelihood of ovulation and pregnancy. Normalization of menstrual cycles and ovulation could occur with modest weight loss as little as 5% of the initial weight. The treatment of obesity includes modifications in lifestyle (diet and exercise) and medical and surgical treatment. In PCOS, anovulation relates to low follicle-stimulating hormone concentrations and the arrest of antral follicle growth in the final stages of maturation. This can be treated with medications such as clomiphene citrate, tamoxifen, aromatase inhibitors, metformin, glucocorticoids, or gonadotropins or surgically by laparoscopic ovarian drilling. In vitro fertilization will remain the last option to achieve pregnancy when others fail. Chronic anovulation over a long period of time is also associated with an increased risk of endometrial hyperplasia and carcinoma, which should be seriously investigated and treated. There are androgenic symptoms that will vary from patient to patient, such as hirsutism, acne, and/or alopecia. These are troublesome presentations to the patients and require adequate treatment. Alternative medicine has been emerging as one of the commonly practiced medicines for different health problems, including PCOS. This review underlines the contribution to the treatment of different symptoms.Keywords: treatment, polycystic ovary syndrome&nbsp