Residual and Past Entropies of Concomitants from Lai And Xie Extensions of Case-II of Generalized Order Statistics and its Dual

In this article, we consider a new extensions of Morgenstern family is Lai and Xie extensions and discuss their concomitants for case-II of generalized order statistics and case-II of dual generalized order statistics. Additionally, recurrence relation between moments is found for the recommended models. We have also derived the expression for the joint distribution of concomitants for case-II of generalized order statistics and its dual. The residual and past entropies are shown last

Prevalence, Electron Microscopy and Molecular Characterization of Cryptosporidium species Infecting Sheep in Egypt

Cryptosporidium sp. is predominant universally and sheep are an imperative zoonotic supply of the disease. Owing to the little information presented with respect to Cryptosporidium sp. infecting sheep, this study was directed to survey the predominance and molecular characterization of Cryptosporidium sp. among sheep of different ages and sexes in Qalyubia governorate, Egypt. The fecal specimens were gathered from 432 sheep of various ages (≤1 to <6, 6-12 and >12 months) and sexes. The samples were microscopically examined after staining by modified Zeihl- Neelsen technique and the intestinal mucosa was scanned by electron microscopy. A nested PCR was connected to amplify a 830 bp of 18S rRNA sequence of Cryptosporidium. RFLP (restriction fragment length polymorphism) technique using SspI and VspI enzymes for digestion of the secondary product of PCR for species identification was applied. The total infection rate was 25.93%. The parasite was more prevalent in males than females of different age groups. Two zoonotic Cryptosporidium species were distinguished after RFLP-PCR sequencing: C. parvum and C. ubiquitum (identified previously as Cervine genotype). The finding recommends that sheep must be considered as a noteworthy potential source of human cryptosporidiosis. A strict reconnaissance of zoonotic cryptosporidiosis must be set up to counteract human infection and to assess forthcoming disease when applying control programs

A neural-network-based model predictive control of three-phase inverter with an output LC Filter

Model predictive control (MPC) has become one of the well-established modern control methods for three-phase inverters with an output $LC$ filter, where a high-quality voltage with low total harmonic distortion (THD) is needed. Although it is an intuitive controller, easy to understand and implement, it has the significant disadvantage of requiring a large number of online calculations for solving the optimization problem. On the other hand, the application of model-free approaches such as those based on artificial neural networks approaches is currently growing rapidly in the area of power electronics and drives. This paper presents a new control scheme for a two-level converter based on combining MPC and feed-forward ANN, with the aim of getting lower THD and improving the steady and dynamic performance of the system for different types of loads. First, MPC is used, as an expert, in the training phase to generate data required for training the proposed neural network. Then, once the neural network is fine-tuned, it can be successfully used online for voltage tracking purpose, without the need of using MPC. The proposed ANN-based control strategy is validated through simulation, using MATLAB/Simulink tools, taking into account different loads conditions. Moreover, the performance of the ANN-based controller is evaluated, on several samples of linear and non-linear loads under various operating conditions, and compared to that of MPC, demonstrating the excellent steady-state and dynamic performance of the proposed ANN-based control strategy

Quasi two-level PWM operation of a nine-arm modular multilevel converter for six-phase medium-voltage motor drives

This paper proposes a hybrid converter for medium-voltage six-phase machine drive systems that mixes the operation of a traditional two-level voltage-source inverter and the modular multilevel converter (MMC) to enable operation over a wide frequency range. Topologically, the proposed converter consists of nine arms resembling two sets of three-phase MMCs with three common arms, yielding a nine-arm MMC with a 25% reduction in the number of employed arms compared to a traditional dual three-phase MMC. The multilevel property of a standard MMC is emulated in the proposed converter, however on a two-level basis, resulting in a stepped two-level output voltage waveform. The proposed converter has a reduced footprint with advantages of small voltage steps, modular structure, and ease of scalability. Further, it is able to drive high-power six-phase machines within low operating frequencies at the rated torque. The operating principle of the converter is elaborated, and its modulation scheme is discussed. The features of the proposed converter are verified through simulations and experimentally

Sudanese Medical Students and Scientific Research

Background: Most of developing countries face problems in assessment of their public health practices. Gain of this knowledge is orchestrated by  research. Medical students can play an essential role in improving public database.Objective: to explore knowledge, attitude and skills of medical students in the Faculty of Medicine and Health Sciences (FMHS), Omdurman Islamic University (OIU) towards research.Materials and Methods: This is a descriptive, analytical, cross-sectional, institution-based study. A total of 442 students, equally from each batch participated in the study. Equal numbers of male andfemale were considered to eliminate gender and seniority bias. Structured pretested questionnaire was used for data collection. Data collected were fed to Statistical Package for Social Sciences(SPSS) version 15. Means, standard deviation and correlations were done where appropriate. Statistical  significance was taken at P =0.05.Results: The mean knowledge score was 37% and attitude was positive in 77.1% of the students. Only 18.3% had attended research methodology workshop. The rate of internet navigation is directly proportional to the social class. Only 14.7% knew the engines used for finding medical literature.Conclusion: The low knowledge score is due to lack of application of research in the academic curriculum; however, the students have a fairly positive attitude. The knowledge is expected to improve with the intended policy to include practical research in the curriculum.Key Words: Public health, academic curriculum, Suda

Effects of Preoperative Sublingual Misoprostol on Uterine Tone during Isoflurane Anesthesia for Cesarean Section

SummaryBackground and objectivesMisoprostol would reduce the uterine bleeding after cesarean delivery without harmful effects on either mother or baby. We aimed to evaluate the effects of preoperative misoprostol on maternal blood loss, uterine tone, and the need for additional oxytocin after cesarean delivery under isoflurane anesthesia.MethodsAfter ethical approval, 366 patients scheduled for elective cesarean delivery were randomly allocated to receive either sublingual misoprostol 400μg (n=179) or placebo tablet (n=187) after intubation. Anesthesia was maintained with 0.5–0.7 MAC isoflurane with nitrous oxide. All patients received intravenous infusion of 10IU of oxytocin after placental delivery. Perioperative estimated blood loss, uterine tone, need for supplementary oxytocin, hematocrit, Apgar scores at 1 and 5 min and adverse effects were recorded.ResultsAfter induction, patients receiving sublingual misoprostol had significant less perioperative estimated blood loss (202±383.1 vs. 708±204.3mL, p<0.001), need for oxytocin (p<0.001), higher hematocrit levels (p<0.001) and uterine tone (p<0.02). The incidence of shivering was higher in the misoprostol group (p=0.04). There were no differences between the two groups as regarding Apgar scores, nausea and vomiting, gastrointestinal disturbances and pyrexia.ConclusionPreoperative administration of sublingual misoprostol 400μg is safe and effective in attenuating the maternal bleeding and uterine atony from isoflurane anesthesia for cesarean delivery

A modular multilevel converter with ripple-power decoupling channels for three-phase MV adjustable-speed drives

This paper presents a drive system based on a modular multilevel converter (MMC) with high-frequency magnetic channels between adjacent-arm submodules (SMs), suitable for medium-voltage, high-power three-phase variable-speed machines. The configuration employs chains of dual half-bridge (DHB) modules linking adjacent SMs of three-phase symmetrical arms. The DHB modules are operating as power channels enabling energy exchange to restore the power imbalance among the SM capacitors. This allows arms' ripple-powers to be entirely decoupled through bidirectional power transfer between adjacent-arm SMs, resulting in a near ripple-free SM capacitor voltage profile. Therefore, the MMC common problem of wide voltage fluctuation across SM capacitors is comprehensively solved, independent of the operating frequency. Additionally, a significant reduction in the sizing requirement of SM capacitance is achieved. The configuration is able to drive multi-megawatt machines from standstill to the rated speed at the rated torque operating condition. The operating principle of the proposed MMC configuration is explained and necessary mathematical analysis is derived. Features and viability of the proposed drive system are verified through simulation and experimentation

A dual modular multilevel converter with shared capacitor sub-module for MV open-end stator winding machine drives

This paper proposes a new dual modular multilevel converter (MMC) topology as a medium-voltage drive for adjustablespeed applications incorporating open-end stator winding machines. A novel concept of sharing one capacitor between each two adjacent-arm sub-modules (SMs) of MMC phaselegs, operating with out-of-phase modulation, is realized through new SM arrangement. This concept allows the MMC to utilize half the number of the SM capacitors, compared to a traditional MMC topology. Additionally, the sizing requirement of the shared capacitor is diminished, which significantly reduces the volume of the drive system and its stored energy. The switching scheme of the shared capacitor between two oppositely modulated SMs eliminates the problem of capacitor wide voltage fluctuations, independent of the operating frequency. Further, the proposed MMC can efficiently operate at near zero frequency, therefore a machine speed-range from zero speed to the rated speed is possible under rated torque operating condition. The proposed MMC topology is elucidated in detail, and its effective performance is verified through simulation

A modular multilevel converter with integrated shared capacitor sub-module for MV motor drives incorporating symmetrical six-phase machines

This paper proposes a new modular multilevel converter (MMC) configuration as a medium-voltage drive for variable-speed applications incorporating symmetrical six-phase machines. The proposed topology employs six MMC phase-legs feeding two isolated groups of three-phase machine windings, each with 60° spatial phase-displacement. A novel concept of sharing one capacitor between each pair of adjacent-arm submodules (SMs) of MMC phase-legs, while feeding machine windings in a spatial phase-opposition, is realized through a new integrated SM arrangement. The integrated SM allows the shared capacitor to absorb and release the same energy amount in a consecutive switching scheme, where the capacitor is experiencing both charging and discharging arm currents, one after another. This results in a limited voltage variation across the SM shared capacitor, independent of the operating frequency. Also, the proposed approach allows the MMC to utilize half the number of the SM capacitors, compared to a traditional MMC topology, while further diminishes the SM capacitance requirement, reducing the volume of the MMC system and its stored energy. The proposed configuration can efficiently operate at near zero frequency, therefore a machine speed-range from zero speed to the rated speed is possible under rated torque operating condition. The proposed MMC topology is elucidated in detail, and its effective performance is verified using simulation