Generic closed loop controller for power regulation in dual active bridge DC-DC converter with current stress minimization

This paper presents a comprehensive and generalized analysis of the bidirectional dual active bridge (DAB) DC/DC converter using triple phase shift (TPS) control to enable closed loop power regulation while minimizing current stress. The key new achievements are: a generic analysis in terms of possible conversion ratios/converter voltage gains (i.e. Buck/Boost/Unity), per unit based equations regardless of DAB ratings, and a new simple closed loop controller implementable in real time to meet desired power transfer regulation at minimum current stress. Per unit based analytical expressions are derived for converter AC RMS current as well as power transferred. An offline particle swarm optimization (PSO) method is used to obtain an extensive set of TPS ratios for minimizing the RMS current in the entire bidirectional power range of - 1 to 1 per unit. The extensive set of results achieved from PSO presents a generic data pool which is carefully analyzed to derive simple useful relations. Such relations enabled a generic closed loop controller design that can be implemented in real time avoiding the extensive computational capacity that iterative optimization techniques require. A detailed Simulink DAB switching model is used to validate precision of the proposed closed loop controller under various operating conditions. An experimental prototype also substantiates the results achieved

Effective M-learning Design Strategies for Computer Science and Engineering Courses

Mobile learning (M-learning) is receiving more attention as a method of delivering to learners study materials anytime and anywhere. It is a necessity for educators to come up with a layout for learning that can be accessed through mobile devices. These learning materials should consist of good quality learning theories and accurate instructional layout in order to maintain learning as effective as possible. It is important to follow certain strategies that can help the developers for M-learning applications. In this paper we propose a set of strategies that are useful for creating mobile prototype for Computer Science and Engineering courses or M-learning application for course content

Preparation and evaluation of mebeverine hydrochloride as mucoadhesive buccal tablet for local anesthesia

Purpose: To formulate and evaluate an antispasmodic drug, mebeverine hydrochloride (Mbv-HCl), as a local anesthetic mucoadhesive buccal tablet.Methods: Mbv-HCl loaded tablets were formulated, using a direct compression technique, with varying polymer concentrations including carbopol 934P alone, carbopol 934P/hydroxypropyl methylcellulose (HPMC) mixture, or carbopol 934P/chitosan mixture. The tablets were evaluated for physicochemical characteristics, in-vitro drug release, bioadhesive strength, swelling, ex-vivo residence time, ex-vivo permeation, drug permeation through the buccal membrane of sheep, and stability.Results: The results indicate that formulation F4, which contains HPMC/carbopol 934P (3:1), showed the best in-vitro drug release profile. The release kinetics for all the formulations fitted well with Hixson- Crowell kinetic model. Bioadhesive strength, surface pH, and swelling index of F4 were 41.52, 6.36, and 231.2 %, respectively. Maximum residence time ex-vivo was exhibited by formulation F4, showing a maximum residence time of about 330 min with 80 % of Mbv-HCl permeated in 6 h ex-vivo. F4 was stable after storage for 60 days at 25 oC/60 % RH and 40 oC/75 % RH, with non-significant change (p < 0.05) in drug content, bioadhesive strength and in vitro release.Conclusion: The optimized mucoadhesive buccal formulation is promising for delivery of Mbv-HCl, and displays high bioadhesion and adequate permeability through sheep buccal membrane to achieve a local anesthetic action.Keywords: Mebeverine hydrochloride, Buccal, Mucoadhesive tablet, Swelling index, Bioadhesive strength, Local anestheti

An Arabic CCG approach for determining constituent types from Arabic Treebank

AbstractConverting a treebank into a CCGbank opens the respective language to the sophisticated tools developed for Combinatory Categorial Grammar (CCG) and enriches cross-linguistic development. The conversion is primarily a three-step process: determining constituents’ types, binarization, and category conversion. Usually, this process involves a preprocessing step to the Treebank of choice for correcting brackets and normalizing tags for any changes that were introduced during the manual annotation, as well as extracting morpho-syntactic information that is necessary for determining constituents’ types. In this article, we describe the required preprocessing step on the Arabic Treebank, as well as how to determine Arabic constituents’ types. We conducted an experiment on parts 1 and 2 of the Penn Arabic Treebank (PATB) aimed at converting the PATB into an Arabic CCGbank. The performance of our algorithm when applied to ATB1v2.0 & ATB2v2.0 was 99% identification of head nodes and 100% coverage over the Treebank data

Antimicrobial resistance pattern and molecular epidemiology of ESBL and MBL producing Acinetobacter baumannii isolated from hospitals in Minia, Egypt

Introduction: Multidrug resistant (MDR) Acinetobacter baumanii (A. baumannii) strains have emerged as novel nosocomial pathogens threatening patients’ lives, especially in intensive-care units (ICUs). This study aims to determine the prevalence of carbapenemase genes and CTX-M-15 and the resistance pattern of carbapenemase producing isolates. Methods: A total of 530 clinical specimens were collected from patients suffering from different infections, antibiotic susceptibility test was performed using kirby-bauer disk diffusion method. ESβL production was detected phenotypically by double-disc synergy test (DDST). Carbapenemase production was tested by Modified Hodge Test (MHT). Then, these isolates were tested for MBL detection by disc potentiation test. Carbapenemase encoding genes (VIM, IMP, GIM and SPM, OXA-51, OXA-23 and OXA-143) and CTX-M-15 were tested by polymerase chain reaction (PCR). Results: Out of 530 samples, 20 bacterial isolates were identified as A. baumannii from different infectious cases, 35% of isolates were ESBL-producers. Eleven isolates were resistant to imipenem (4 isolates) and meropenem (7 isolates). All carbapenem resistant isolates were MHT positive. Nine (45%) isolates were confirmed as A. baumannii by OXA-51 (all were carbapenem resistant). Distribution of IMP, VIM, GIM and SPM, OXA-23, OXA-143 and CTX-M-15 by PCR were 55, 50, 50, 25, 35, 45 and 33% respectively. Conclusion: The high prevalence of resistance genes and the resistance pattern of the isolates indicate that the detection of ESBLs and MBLs phenotypically and genotypically with the study of the resistance pattern of the isolates is critically important for the surveillance of drug resistance in the hospital environment

Utilization of Some Fruits and Vegetables By-Products to Produce High Dietary Fiber Jam

The present study aimed to investigate the chemical composition, antioxidant activity, total phenolic compounds and ?-carotene of carrot peels, apple pomace, banana peels and mandarin peels and their quality in preparing jam. Mandarin and banana peels characterized by its higher crude fiber (12.16 and 5.25%) and vitamin C (68 and 16.6 mg/100g) compared to carrot peels (3.91%) and apple pomace (3.65%). Banana peels contained higher amount of magnesium, potassium, calcium and iron compared to other peels samples. Therefore, jam of banana peels characterized by its higher content in magnesium (758 mg/100g), potassium (779 mg/100g), calcium (191 mg/100g) and iron (59.15 mg/100g). Jam of apple pomace characterized by its higher phosphorus contents (220 mg/100g) followed by jam of banana peels (138 mg/100g), mandarin peels (128 mg/100g) and carrot peels (53 mg/100g). Jam of carrot peels characterized by its higher phenolics content as gallic acid equivalent (87.4 mg/100g) followed by jams of apple pomace (82.5 mg/100g), banana peels (42.7 mg/100g) and mandarin peels (34.6 mg/100g). The same trend was observed in total flavonoids as catechen equivalent (mg CAT/100g) in jams of carrot peels, apple pomace, banana peels and mandarin peels, where they were 35.9, 30.1, 23.5 and 21.7, respectively. Furthermore, jam of carrot peels had higher antioxidant activity, where its DPPH radical, had lower DPPH based IC50 (1.8 ?g/ml) while jam of apple pomace, banana peels and mandarin peels had higher DPPH based IC50 reached to 2.04, 2.21 and 3.34 µg/ml, respectively. The same trend was observed for the ?-carotene radical in tested jam samples. Hunter color parameter showed that jam of mandarin peels had highest lightness (L* = 39.8), followed by jam of carrot peels (29.46), apple pomace (18.27) and banana peels (15.19). Therefore, jam of banana peels was darker than other tested peels samples. Sensory evaluation showed that jam of apple pomace characterized by its higher taste and odor, followed by jam of mandarin peels, banana peels and carrot peels. Color of tested jam of carrot, banana or mandarin peels was darker than apple pomace jam. Also, jam of apple pomace gave higher scores in appearance and overall acceptability. Keywords: Jam – Peels – antioxidant activity – Total phenolics– Total Flavonoid

A new active power controller in dual active bridge DC-DC converter with a minimum-current-point-tracking technique

This article proposes a new controller for power regulation in dual active bridge (DAB) dc-dc converter based on a new scheme that tracks minimum RMS current to ensure minimum losses. The proposed controller is based on an implementation of perturb and observe (PO) tracking method that enables minimum current point tracking (MCPT) at any desired level of active power transfer and dc voltage ratio. The PO is embedded in a closed-loop control scheme which simultaneously regulates active power in DAB converter. The nonlinear I - V characteristic of DAB presents the basis for this proposed controller and the rationale of using PO algorithm. The proposed controller does not require complex nonlinear converter modeling and is not circuit parameter dependent. Design procedure of the proposed controller is presented, and extensive simulation is carried out using MATLAB/Simulink to validate the effectiveness of the proposed MCPT closed-loop controller. An experimental prototype also substantiates the results achieved