Study of Short-Circuit Currents Around Dĕtmarovice Power Station

Shehab Abdulwadood Ali 한국전기전자재료학회 2014 Transactions on Electrical and Electronic Material Vol.15 No.3

The calculation of short-circuit currents is important for power systems operation and restoration, and fordetermining the means to protect human lives and properties. In this paper, a part of a power system network,around the Dĕtmarovice power station in Czech Republic, was simulated by the well known program EMTP-ATPDraw(Electromagnetic Transients Program-Alternative Transient Program), and short-circuit currents and voltageswere calculated at different points in the electric network and presented as a time function by the PlotXY program. Calculations were done just for phase-to-ground, and for the three-phase short-circuit at the Kunčice substation. Theresults were important for determining the characteristics of the equipment required to withstand or break the shortcircuitcurrent; for this reason, the calculations were repeated using earth-fault resistances only for the case of busbarKUN shown in Figs. 5 and 6.

Modeling of Power Networks by ATP-Draw for Harmonics Propagation Study

Shehab Abdulwadood Ali 한국전기전자재료학회 2013 Transactions on Electrical and Electronic Material Vol.14 No.6

This paper illustrates the possibilities of using the program ATP-Draw (Alternative Transient Program) for the modeling of power networks to study power quality problems with highly detailed analyses. The Program ATP-Draw is one of the most widespread and oldest programs. A unique characteristic of this program is its public domain and the existence of forums and study committees where new application cases and modification are presented and shared publicly. In this paper, to study the propagation of harmonics through a power network, a part of an industrial power network was modeled. The network contains different types of electric components, such as transformers,transmission lines, cables and loads, and there is a source of harmonics that injects 3rd, 5th, 7th, 9th and 11th harmonic currents into the network, causing a distortion of the wave form of the currents and voltages through the power network.

Polyamide 6/tallow modified clay nanofibrous mat coupled with hydrogels for potential topical/transdermal delivery of doxycycline hydrochloride

Shehab-ElDin Amira Nagy,Sobh Rokaya Aly,Rabie Abdelgawad Mohamed,Mohamed Wael Sabry,Nasr Hanaa Elsayed 한국약제학회 2023 Journal of Pharmaceutical Investigation Vol.53 No.2

Purpose Current innovations in pharmaceutical industries involve the design of functionalized materials for drug delivery applications. Hybrid-bilayer patches of electrospun polyamide 6/tallow modified clay nanocomposite fibers coupled with hydrogels comprising sodium alginate (NaAlg), polyvinyl alcohol (PVA), or a mixture of both were developed. Methods The hydrogel precursors were crosslinked either ionically using a CaCl2 solution or physically through repeated freezing–thawing cycles to avoid toxic crosslinking agents. Doxycycline hydrochloride was loaded either by adsorption or active loading methods. The hybrid bilayer patches were evaluated for their physicochemical and morphological properties. Furthermore, in vitro drug release studies in phosphate-buffered saline (PBS) (pH 7.4) and acetate buffer (pH 5.5) were performed, along with antimicrobial activity and toxicity tests. Results An increase in the NaAlg ratio caused a gradual decrease in the gel content while greatly increasing the swelling ability. Porous structures were also produced. The in-vitro drug release profiles and corresponding kinetics were mainly dependent on structural factors. An initial burst release was observed from the CaAlg nanofibers (approximately 61.5% ± 0.68% and 52% ± 1.22% of the drug was released during the first 2 h in PBS and acetate buffer, respectively), whereas a relatively slow release rate was achieved from the nanofibers of the physically crosslinked PVA or PVA/NaAlg. The antimicrobial test confirmed that the loaded drug retained its antimicrobial efficacy. The toxicity test using the “Microtox analyzer model 500” exhibited EC50 ≥ 100, indicating no toxic effect against the luminescent marine bacteria Vibrio fischeri. Conclusion The fabricated functionalized patches showed great potential for topical/transdermal drug delivery.

Strengthening of Cutouts in Existing One-Way Spanning R. C. Flat Slabs Using CFRP Sheets

Shehab, Hamdy K.,Eisa, Ahmed S.,El-Awady, Kareem A. Korea Concrete Institute 2017 International Journal of Concrete Structures and M Vol.11 No.2

Openings in slabs are usually required for many different applications such as aeriation ducts and air conditioning. Opening in concrete slabs due to cutouts significantly decrease the member stiffness. There are different techniques to strengthen slabs with opening cutouts. This study presents experimental and numerical investigations on the use of Carbon Fiber Reinforced Polymers (CFRP) as strengthening material to strengthen and restore the load carrying capacity of R.C. slabs after having cutout in the hogging moment region. The experimental program consisted of testing five (oneway spanning R.C. flat slabs) with overhang. All slabs were prismatic, rectangular in cross-section and nominally 2000 mm long, 1000 mm width, and 100 mm thickness with a clear span (distance between supports) of 1200 mm and the overhang length is 700 mm. All slabs were loaded up to 30 kN (45% of ultimate load for reference slab, before yielding of the longitudinal reinforcement), then the load was kept constant during cutting concrete and steel bars (producing cut out). After that operation, slabs were loaded till failure. An analytical study using finite element analysis (FEA) is performed using the commercial software ANSYS. The FEA has been validated and calibrated using the experimental results. The FE model was found to be in a good agreement with the experimental results. The investigated key parameters were slab aspect ratio for the opening ratios of [1:1, 2:1], CFRP layers and the laminates widths, positions for cutouts and the CFRP configurations around cutouts.

Study of Short-Circuit Currents Around Dĕtmarovice Power Station

Ali, Shehab Abdulwadood The Korean Institute of Electrical and Electronic 2014 Transactions on Electrical and Electronic Material Vol.15 No.3

The calculation of short-circuit currents is important for power systems operation and restoration, and for determining the means to protect human lives and properties. In this paper, a part of a power system network, around the D$\breve{e}$tmarovice power station in Czech Republic, was simulated by the well known program EMTP-ATPDraw (Electromagnetic Transients Program-Alternative Transient Program), and short-circuit currents and voltages were calculated at different points in the electric network and presented as a time function by the PlotXY program. Calculations were done just for phase-to-ground, and for the three-phase short-circuit at the Kun$\check{c}$ice substation. The results were important for determining the characteristics of the equipment required to withstand or break the short-circuit current; for this reason, the calculations were repeated using earth-fault resistances only for the case of busbar KUN shown in Figs. 5 and 6.

Modeling of Power Networks by ATP-Draw for Harmonics Propagation Study

Ali, Shehab Abdulwadood The Korean Institute of Electrical and Electronic 2013 Transactions on Electrical and Electronic Material Vol.14 No.6

This paper illustrates the possibilities of using the program ATP-Draw (Alternative Transient Program) for the modeling of power networks to study power quality problems with highly detailed analyses. The Program ATP-Draw is one of the most widespread and oldest programs. A unique characteristic of this program is its public domain and the existence of forums and study committees where new application cases and modification are presented and shared publicly. In this paper, to study the propagation of harmonics through a power network, a part of an industrial power network was modeled. The network contains different types of electric components, such as transformers, transmission lines, cables and loads, and there is a source of harmonics that injects $3^{rd}$, $5^{th}$, $7^{th}$, $9^{th}$ and $11^{th}$ harmonic currents into the network, causing a distortion of the wave form of the currents and voltages through the power network.

Strengthening of Cutouts in Existing One-Way Spanning R. C. Flat Slabs Using CFRP Sheets

Hamdy K. Shehab,Ahmed S. Eisa,Kareem A. El-Awady 한국콘크리트학회 2017 International Journal of Concrete Structures and M Vol.11 No.2

Openings in slabs are usually required for many different applications such as aeriation ducts and air conditioning. Opening in concrete slabs due to cutouts significantly decrease the member stiffness. There are different techniques to strengthen slabs with opening cutouts. This study presents experimental and numerical investigations on the use of Carbon Fiber Reinforced Polymers (CFRP) as strengthening material to strengthen and restore the load carrying capacity of R.C. slabs after having cutout in the hogging moment region. The experimental program consisted of testing five (oneway spanning R.C. flat slabs) with overhang. All slabs were prismatic, rectangular in cross-section and nominally 2000 mm long, 1000 mm width, and 100 mm thickness with a clear span (distance between supports) of 1200 mm and the overhang length is 700 mm. All slabs were loaded up to 30 kN (45% of ultimate load for reference slab, before yielding of the longitudinal reinforcement), then the load was kept constant during cutting concrete and steel bars (producing cut out). After that operation, slabs were loaded till failure. An analytical study using finite element analysis (FEA) is performed using the commercial software ANSYS. The FEA has been validated and calibrated using the experimental results. The FE model was found to be in a good agreement with the experimental results. The investigated key parameters were slab aspect ratio for the opening ratios of [1:1, 2:1], CFRP layers and the laminates widths, positions for cutouts and the CFRP configurations around cutouts.

Could the Breast Prognostic Biomarker Status Change During Disease Progression? An Immunohistochemical Comparison between Primary Tumors and Synchronous Nodal Metastasis

El Nemr Esmail, Reham Shehab,El Farouk Abdel-Salam, Lubna Omer,Abd El Ellah, Mohammed M Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.10

Background: Prognostic biomarkers in breast cancer are routinely investigated in the primary tumors to guide further management. However, it is proposed that the expression may change during the disease progression, and may result in a different immune profile in the metastatic nodes. This work aimed to investigate the expression of breast prognostic biomarkers in primary tumors and in its axillary nodal metastasis, to estimate the possible discordant expression. Materials and Methods: 60 paired primary and axillary nodal metastasis samples were collected from patients with primary breast cancer with positive nodal deposits, diagnosed at the Maadi Military Hospital, Cairo, Egypt, during the year 2013. ER, PR and HER2 expression was assessed by immunohistochemistry in all samples Results: 48.3% of the included cases showed concordant results for both ER and PR receptors between the primary tumor and its nodal metastasis while 51.7% showed discordant results and the discordance level was statistically significant. On the other hand, 70% of the cases showed concordant Her2 results between the primary tumors and the nodal deposits, 30% showed discordant results and the difference was significant. Conclusions: The study indicated that the discordance in ER and PR receptor expression between the primary breast tumor and their nodal metastasis may be significant. The possible switch in the biomarker status during the disease progression is worth noting and may change the patient therapeutic planning. So, whether the treatment selection should be based on biomarkers in the lymph node is a topic for further studies and future clinical trials.

Dynamic Model of PEM Fuel Cell Using Real-time Simulation Techniques

Jee-Hoon Jung,Shehab Ahmed 전력전자학회 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.6

The increased integration of fuel cells with power electronics, critical loads, and control systems has prompted recent interest in accurate electrical terminal models of the polymer electrolyte membrane (PEM) fuel cell. Advancement in computing technologies, particularly parallel computation techniques and various real-time simulation tools have allowed the prototyping of novel apparatus to be investigated in a virtual system under a wide range of realistic conditions repeatedly, safely, and economically. This paper builds upon both advancements and provides a means of optimized model construction boosting computation speeds for a fuel cell model on a real-time simulator which can be used in a power hardware-in-the-loop (PHIL) application. Significant improvement in computation time has been achieved. The effectiveness of the proposed model developed on Opal RT’s RT-Lab Matlab/Simulink based real-time engineering simulator is verified using experimental results from a Ballard Nexa fuel cell system.

Fundamental Output Voltage Enhancement of Half-Bridge Voltage Source Inverter with Low DC-link Capacitance

Ahmed Elserougi,Ahmed Massoud,Shehab Ahmed 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

Conventionally, in order to reduce the ac components of the dc-link capacitors of the two-level Half-Bridge Voltage Source Inverter (HB-VSI), high dc-link capacitances are required. This necessitates the employment of short-lifetime and bulky electrolytic capacitors. In this paper, an analysis for the performance of low dc-link capacitances-based HB-VSI is presented to elucidate its ability to generate an enhanced fundamental output voltage magnitude without increasing the voltage rating of the involved switches. This feature is constrained by the load displacement factor. The introduced enhancement is due to the ac components of the capacitors’ voltages. The presented approach can be employed for multi-phase systems through using multi single-phase HB-VSI(s). Mathematical analysis of the proposed approach is presented in this paper. To ensure a successful operation of the proposed approach, a closed loop current controller is examined. An expression for the critical dc-link capacitance, which is the lowest dc-link capacitance that can be employed for unipolar capacitors’ voltages, is derived. Finally, simulation and experimental results are presented to validate the proposed claims.