NUMERICAL STUDY OF TURBULENCE DYNAMICS IN PLUNGING & SURGING BREAKING WAVES

KHAYYER ABBAS,YEGANEH-BAKHTIARY ABBAS,GHAHERI ABBAS,GOTOH HITOSHI,SAKAI TETSUO 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

Free vibration analysis of a piezoelectric nanobeam using nonlocal elasticity theory

Abbas Kaghazian,Ali Hajnayeb,Hamidreza Foruzande 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.5

Piezoelectric nanobeams are used in several nano electromechanical systems. The first step in designing these systems is conducting a vibration analysis. In this research, the free vibration of a piezoelectric nanobeam is analyzed by using the nonlocal elasticity theory. The nanobeam is modeled based on Euler-Bernoulli beam theory. Hamilton’s principle is used to derive the equations of motion and also the boundary conditions of the system. The obtained equations of motion are solved by using both Galerkin and the Differential Quadrature (DQ) methods. The clamped-clamped and cantilever boundary conditions are analyzed and the effects of the applied voltage and nonlocal parameter on the natural frequencies and mode shapes are studied. The results show the success of Galerkin method in determining the natural frequencies. The results also show the influence of the nonlocal parameter on the natural frequencies. Increasing a positive voltage decreases the natural frequencies, while increasing a negative voltage increases them. It is also concluded that for the clamped parts of the beam and also other parts that encounter higher values of stress during free vibrations of the beam, anti-nodes in voltage mode shapes are observed. On the contrary, in the parts of the beam that the values of the induced stress are low, the values of the amplitude of the voltage mode shape are not significant. The obtained results and especially the mode shapes can be used in future studies on the forced vibrations of piezoelectric nanobeams based on Galerkin method.

Neurologic Complications in Percutaneous Nephrolithotomy

Abbas Basiri,Mohammad Hossein Soltani,Mohammadreza Kamranmanesh,Ali Tabibi,Seyed Amir Mohsen Ziaee,Akbar Nouralizadeh,Farzaneh Sharifiaghdas,Mahtab Poorzamani,Babak Gharaei,Ardalan Ozhand,Alireza Lash 대한비뇨의학회 2013 Investigative and Clinical Urology Vol.54 No.3

Purpose: Percutaneous nephrolithotomy (PCNL) has been the preferred procedure for the removal of large renal stones in Iran since 1990. Recently, we encountered a series of devastating neurologic complications during PCNL, including paraplegia and hemiplegia. There are several reports of neurologic complications following PCNL owing to paradoxical air emboli, but there are no reports of paraplegia following PCNL. Materials and Methods: We retrospectively reviewed the medical records of patients who had undergone PCNL in 13 different endourologic centers and retrieved data related to neurologic complications after PCNL, including coma, paraplegia, hemiplegia,and quadriplegia. Results: The total number of PCNL procedures in these 13 centers was 30,666. Among these procedures, 11 cases were complicated by neurologic events, and four of these cases experienced paraplegia. All events happened with the patient in the prone position with the use of general anesthesia and in the presence of air injection. There were no reports of neurologic complications in PCNL procedures performed with the patient under general anesthesia and in the prone position and with contrast injection. Conclusions: It can be assumed that using room air to opacify the collecting system played a major role in the occurrence of these complications. Likewise, the prone position and general anesthesia may predispose to these events in the presence of air injection.

The Content and Necessity of the New International Order in the New International Environment

Abbas Maleki 한국중동학회 1991 韓國 中東 學會 論叢 Vol.12 No.1

Characterization of Adpative Modulators in Fixed Wireless ATM Networks

Abbas Mohammadi,Surinder Kumar 한국통신학회 2004 Journal of communications and networks Vol.6 No.2

Highly functionalized nanoporous thin carbon paper electrodes for high energy density of zero-gap vanadium redox flow battery

Abbas, Saleem,Mehboob, Sheeraz,Shin, Hyun-Jin,Han, Oc Hee,Ha, Heung Yong Elsevier 2019 Chemical Engineering Journal Vol. No.

<P><B>Abstract</B></P> <P>Low energy density of a vanadium redox flow battery (VRFB) due to limited solubility and stability of vanadium ions constrains its wide spread applications and this issue becomes more critical by low active surface areas of electrodes and mass transport limitations of active species on the electrodes that lead to low electrolyte utilization. In this study the issue of low energy density is addressed by improving the electrode performance through modifying the surface properties and morphology of thin (0.19 mm thick) carbon paper electrodes instead of commonly used several millimeters thick carbon felts. Surface functionalization and pore formation of carbon paper are carried out using a catalytic etching method at high temperaturewhere the diameters of nanopores are controlled by tuning the etching conditions. The synergistic effects of thin, nanoporous and functionalized carbon paper result in more effective electrode/electrolyte interaction and the less mass transport resistance. Therefore, the zero-gap VRFB cell employing the nanoporous electrodes displays remarkable performance improvement in terms of electrolyte utilization by 110%, discharge energy density by 155% and energy efficiency by 29% as compared to the one using pristine electrodes at a current density of 50 mA cm<SUP>−2</SUP>. The results imply that the more energy can be harvested by employing nanoporous and functionalized carbon paper electrodes having larger active surface areas.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Issue of low energy density of VRFB is addressed by modifying electrode surface. </LI> <LI> Highly functionalized nanopores are formed on the surface of thin carbon papers. </LI> <LI> Surface area, wettability and electrode/electrolyte contact is highly improved. </LI> <LI> Electrolyte utilization for cell having modified electrodes is improved by 110%. </LI> <LI> 27 Wh L<SUP>−1</SUP> more energy is harvested with 29% higher energy efficiency at 50 mA cm<SUP>−2</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effects of Platelet-Rich Plasma on Kidney Regeneration in Gentamicin-Induced Nephrotoxicity

Abbas Moghadam,,Tahereh Talaei-Khozani,Afsaneh Mafi,Mohammad Reza Namavar,Farzaneh Dehghani 대한의학회 2017 Journal of Korean medical science Vol.32 No.1

Platelet-rich plasma (PRP) as a source of growth factors may induce tissue repairing and improve fibrosis. This study aimed to assess the effects of PRP on kidney regeneration and fibrosis in gentamicin (GM)-induced nephrotoxicity rat model by stereological study. Thirty-two male rats were selected. Nephrotoxicity was induced in animals by administration of GM (80 mg/kg/daily, intraperitoneally [IP], 8 day) and animals were treated by PRP (100 µL, intra-cortical injection using surgical microscopy, single dose). Blood samples were collected for determine blood urea nitrogen (BUN) and creatinine (Cr) before and after PRP therapy. At the end of experiment, right kidneys were sectioned by Isotropic Uniform Random (IUR) method and stained with H & E and Masson’s Trichrome. The stereological methods were used for estimating the changes in different structures of kidney. PRP increased the number of epithelial cells in convoluted tubules, and decreased the volume of connective tissue, renal corpuscles and glomeruli in GM-treated animals (P < 0.05). Our findings indicate that PRP had beneficial effects on proliferation of epithelial cells in convoluted tubules and ameliorated GM-induced fibrosis.

Changing the Care Process: A New Concept in Iranian Rural Health Care

Abbas Abbaszadeh,Manijeh Eskandari,Fariba Borhani 한국간호과학회 2013 Asian Nursing Research Vol.7 No.1

Purpose: Health care delivery systems in rural areas face numerous challenges in meeting the community’s needs. There is a lack of adequate attention for this problem. This study aims to explore the challenges of the health care process in rural Iran according to health care providers’ experiences. Methods: This was a qualitative study that used the content analysis method. We selected a total of 21 health care providers based on purposive sampling. Data collection consisted of semi-structured individual interviews that were analyzed by qualitative content analysis. Results: Data analysis led to the formation of one main category, the challenges of process of health care in rural society. Within this main category, we created the following subcategories: change in characteristics of the rural society, increase in complexity of the health care process, decrease in workforce efficiency, and decrease in propensity of people’s care. Conclusion: The findings of this study indicate that the process of health care in Iranian rural society is changing rapidly with community health workers encountering new challenges. There is diminished efficiency in responding to the changing care process in Iran’s rural society. Considering this change in process of care, therefore, the health care system should respond to these new challenges by establishing new health care models. Purpose: Health care delivery systems in rural areas face numerous challenges in meeting the community’s needs. There is a lack of adequate attention for this problem. This study aims to explore the challenges of the health care process in rural Iran according to health care providers’ experiences. Methods: This was a qualitative study that used the content analysis method. We selected a total of 21 health care providers based on purposive sampling. Data collection consisted of semi-structured individual interviews that were analyzed by qualitative content analysis. Results: Data analysis led to the formation of one main category, the challenges of process of health care in rural society. Within this main category, we created the following subcategories: change in characteristics of the rural society, increase in complexity of the health care process, decrease in workforce efficiency, and decrease in propensity of people’s care. Conclusion: The findings of this study indicate that the process of health care in Iranian rural society is changing rapidly with community health workers encountering new challenges. There is diminished efficiency in responding to the changing care process in Iran’s rural society. Considering this change in process of care, therefore, the health care system should respond to these new challenges by establishing new health care models.

Cd-doped SnO2-reduced Graphene Oxide Composite Nanofibrous Mats as CO Gas Sensors

Abbas Mobasheri,Saeed Parhoodeh,Gholamabbas Shams 한국섬유공학회 2022 Fibers and polymers Vol.23 No.3

In this study, SnO2 nanofibers and their modifications (Cd doping and making a composite with reduced grapheneoxide) were synthesized via electrospinning and employed as CO gas sensing. The enhanced sensing properties of Cd-dopedSnO2-RGO nanofibrous mat comparing to other counterparts could be ascribed to p-type behavior of RGO inside thenanofibers and catalytic activity and adding new sites for oxidation of cadmium elements, which offered flexible andoptimum gas sensing. These mats had a specific surface area of 74.56 m2/g with 10.65 nm cylindrical slender channels andaverage fiber diameter of 200.57 nm.

Multi Objective Calibration of Large Scaled Water Quality Model Using a Hybrid Particle Swarm Optimization and Neural Network Algorithm

Abbas Afshar,Hamideh Kazemi 대한토목학회 2012 KSCE Journal of Civil Engineering Vol.16 No.6

Large scaled simulation models, especially the water quality simulation models, are so complicated that makes calibration processes huge tasks; in order to attain optimum solution, lots of parameters must be calibrated, simultaneously. Methods based on evolutionary algorithm developed new horizons in calibration procedure. Hybrid algorithms are of the newest. In hybrid algorithms,one of the modules is applied as a simulator and the other one takes role as an optimization module. In this article, overcoming these challenges, hybrid ANN-PSO algorithm is applied in calibration process of water quality model CE-QUAL-W2. Here, Particle Swarm Optimization (PSO) provides simulation (CE-QUAL-W2) model with sets of parameters to simulate model. Using these results, Neural Network (estimator) is trained. In the next step, simulator would be replaced with estimator and Artificial Neural Network (ANN) would estimate simulator’s behavior in a way less time. The first goal is to calibrate thermal parameter; going forward through this process needs water surface elevation parameter to be calibrated, too. As a result, the proposed model will become multi-objective one, applied in Karkheh reservoir in Iran during 6 month simulation period. The proposed approach overcomes the high computational efforts required if a conventional calibration search technique was used, while retaining the quality of the final calibration results. Estimator (ANN) embedded in optimization algorithm (PSO) in calibration process,undoubtedly, reduced run time while the answers have reliable quality.