Response surface methodology based multi-objective optimization of tuned mass damper for jacket supported offshore wind turbine

Rahman, Mohammad S.,Islam, Mohammad S.,Do, Jeongyun,Kim, Dookie Techno-Press 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.3

This paper presents a review on getting a Weighted Multi-Objective Optimization (WMO) of Tuned Mass Damper (TMD) parameters based on Response Surface Methodology (RSM) coupled central composite design and Weighted Desirability Function (WDF) to attenuate the earthquake vibration of a jacket supported Offshore Wind Turbine (OWT). To optimize the parameters (stiffness and damping coefficient) of damper, the frequency ratio and damping ratio were considered as a design variable and the top displacement and frequency response were considered as objective functions. The optimization has been carried out under only El Centro earthquake results and after obtained the optimal parameters, more two earthquakes (California and Northridge) has been performed to investigate the performance of optimal damper. The obtained results also compared with the different conventional TMD's designed by Den Hartog's, Sadek et al.'s and Warburton's method. From the results, it was found that the optimal TMD based on RSM shows better response than the conventional damper. It is concluded that the proposed response model offers an efficient approach regarding the TMD optimization.

Response surface methodology based multi-objective optimization of tuned mass damper for jacket supported offshore wind turbine

Mohammad S. Rahman,Mohammad S. Islam,도정윤,김두기 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.63 No.3

This paper presents a review on getting a Weighted Multi-Objective Optimization (WMO) of Tuned Mass Damper (TMD) parameters based on Response Surface Methodology (RSM) coupled central composite design and Weighted Desirability Function (WDF) to attenuate the earthquake vibration of a jacket supported Offshore Wind Turbine (OWT). To optimize the parameters (stiffness and damping coefficient) of damper, the frequency ratio and damping ratio were considered as a design variable and the top displacement and frequency response were considered as objective functions. The optimization has been carried out under only El Centro earthquake results and after obtained the optimal parameters, more two earthquakes (California and Northridge) has been performed to investigate the performance of optimal damper. The obtained results also compared with the different conventional TMD‟s designed by Den Hartog‟s, Sadek et al.‟s and Warburton‟s method. From the results, it was found that the optimal TMD based on RSM shows better response than the conventional damper. It is concluded that the proposed response model offers an efficient approach regarding the TMD optimization.

Antimicrobial activity and cytotoxicity of Eclipta prostrata

Rahman, Mohammad S.,Rashid, Mohammad A. Kyung Hee Oriental Medicine Research Center 2008 Oriental pharmacy and experimental medicine Vol.8 No.1

The plant Eclipta prostrata, a member of the Compositae family, has folkloric reputation of being used as a medicinal agent in Bangladesh. In the present investigation, attempt was taken to explore the antimicrobial potency and cytotoxicity of its extractives and purified compounds. The methanolic extract of the whole plant, its n-hexane, carbon tetrachloride, chloroform, aqueous soluble fractions and two purified compounds, eclalbasaponin I (1) and II (2), obtained from Eclipta prostrata were subjected to screening for inhibition of microbial growth by the disc diffusion method at 300 and 100 ${\mu}g$/disc for extracts and pure compounds, respectively. In this case, the carbon tetrachloride and chloroform soluble fractions of the methanolic extract appeared very potent in terms of both zone of inhibition and spectrum of activity. However, all the extractives were also subjected to brine shrimp lethality bioassay for preliminary cytotoxicity evaluation. Here, the carbon tetrachloride soluble fraction of methanolic extract revealed the strongest cytotoxicity having $LC_{50}$ of 1.318 ${\mu}g$/ml.

Antimicrobial activity and cytotoxicity of Eclipta prostrata

Mohammad S Rahman,Mohammad A Rashid 경희대학교 융합한의과학연구소 2008 Oriental Pharmacy and Experimental Medicine Vol.8 No.1

The plant Eclipta prostrata, a member of the Compositae family, has folkloric reputation of being used as a medicinal agent in Bangladesh. In the present investigation, attempt was taken to explore the antimicrobial potency and cytotoxicity of its extractives and purified compounds. The methanolic extract of the whole plant, its n-hexane, carbon tetrachloride, chloroform, aqueous soluble fractions and two purified compounds, eclalbasaponin I (1) and II (2), obtained from Eclipta prostrata were subjected to screening for inhibition of microbial growth by the disc diffusion method at 300 and 100 μg/disc for extracts and pure compounds, respectively. In this case, the carbon tetrachloride and chloroform soluble fractions of the methanolic extract appeared very potent in terms of both zone of inhibition and spectrum of activity. However, all the extractives were also subjected to brine shrimp lethality bioassay for preliminary cytotoxicity evaluation. Here, the carbon tetrachloride soluble fraction of methanolic extract revealed the strongest cytotoxicity having LC50 of 1.318 μg/ml. The plant Eclipta prostrata, a member of the Compositae family, has folkloric reputation of being used as a medicinal agent in Bangladesh. In the present investigation, attempt was taken to explore the antimicrobial potency and cytotoxicity of its extractives and purified compounds. The methanolic extract of the whole plant, its n-hexane, carbon tetrachloride, chloroform, aqueous soluble fractions and two purified compounds, eclalbasaponin I (1) and II (2), obtained from Eclipta prostrata were subjected to screening for inhibition of microbial growth by the disc diffusion method at 300 and 100 μg/disc for extracts and pure compounds, respectively. In this case, the carbon tetrachloride and chloroform soluble fractions of the methanolic extract appeared very potent in terms of both zone of inhibition and spectrum of activity. However, all the extractives were also subjected to brine shrimp lethality bioassay for preliminary cytotoxicity evaluation. Here, the carbon tetrachloride soluble fraction of methanolic extract revealed the strongest cytotoxicity having LC50 of 1.318 μg/ml.

Preliminary antimicrobial and cytotoxic activities of Amoora cucullata extractives

Rahman, Mohammad S.,Rashid, Mohammad A. Kyung Hee Oriental Medicine Research Center 2009 Oriental pharmacy and experimental medicine Vol.9 No.2

Amoora cucullata (Meliaceae), a mangrove plant, has folkloric reputation as a medicinal agent in Bangladesh. In this study, the n-hexane, ethyl acetate and methanolic extracts of the stem bark of this plant were subjected to microbiological investigation and brine shrimp lethality bioassay. In case of antimicrobial screening, the ethyl acetate and methanolic extracts appeared to be potent in terms of both zone of inhibition and spectrum of activity showing the average zones of inhibition 8 - 14 mm and 9 - 16 mm, respectively. In the brine shrimp lethality bioassay, the methanolic extract demonstrated highest cytotoxicity having $LC_{50}$ of $0.549{\mu}g/ml$, whereas the ethyl acetate and n-hexane extract showed $LC_{50}$ of 7.943 and $17.180{\mu}g/ml$, respectively.

Preliminary antimicrobial and cytotoxic activities of Amoora cucullata extractives

Mohammad S Rahman,Mohammad A Rashid 경희대학교 융합한의과학연구소 2009 Oriental Pharmacy and Experimental Medicine Vol.9 No.2

Amoora cucullata (Meliaceae), a mangrove plant, has folkloric reputation as a medicinal agent in Bangladesh. In this study, the n-hexane, ethyl acetate and methanolic extracts of the stem bark of this plant were subjected to microbiological investigation and brine shrimp lethality bioassay. In case of antimicrobial screening, the ethyl acetate and methanolic extracts appeared to be potent in terms of both zone of inhibition and spectrum of activity showing the average zones of inhibition 8 - 14 mm and 9 - 16 mm, respectively. In the brine shrimp lethality bioassay, the methanolic extract demonstrated highest cytotoxicity having LC50 of 0.549 μg/ml, whereas the ethyl acetate and n-hexane extract showed LC50 of 7.943 and 17.180 μg/ml, respectively. Amoora cucullata (Meliaceae), a mangrove plant, has folkloric reputation as a medicinal agent in Bangladesh. In this study, the n-hexane, ethyl acetate and methanolic extracts of the stem bark of this plant were subjected to microbiological investigation and brine shrimp lethality bioassay. In case of antimicrobial screening, the ethyl acetate and methanolic extracts appeared to be potent in terms of both zone of inhibition and spectrum of activity showing the average zones of inhibition 8 - 14 mm and 9 - 16 mm, respectively. In the brine shrimp lethality bioassay, the methanolic extract demonstrated highest cytotoxicity having LC50 of 0.549 μg/ml, whereas the ethyl acetate and n-hexane extract showed LC50 of 7.943 and 17.180 μg/ml, respectively.

Control of an Exoskeleton Robot Arm with Sliding Mode Exponential Reaching Law

Mohammad H. Rahman,Maarouf Saad,Jean-Pierre Kenné,Philippe S. Archambault 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.1

Robots are now working not only in human environments but also interacting with humans, e.g., service robots or assistive robots. A 7DoFs robotic exoskeleton MARSE-7 (motion assistive robotic-exoskeleton for superior extremity) was developed as an assistive robot to provide movement as-sistance and/or ease daily upper-limb motion. In this paper, we highlight the nonlinear control of MARSE-7 using the modified sliding mode exponential reaching law (mSMERL). Conventional sliding control produces chattering which is undesired for this kind of robotic application as it causes damage to the mechanical structure. Compared to conventional sliding control, our approach significantly re-duces chattering and delivers a high dynamic tracking performance. The control architecture was im-plemented on a field-programmable gate array (FPGA) in conjunction with a RT-PC. In experiments, trajectory tracking that corresponds to typical passive arm movement exercises for single and multi joint movements were performed to evaluate the performance of the developed robot and the controller. Experimental results demonstrate that the MARSE-7 can effectively track the desired trajectories.

Production of Biosurfactant as Potential Food Bioemulsifier by Bacillus sp. Isolated From Sirri Island, Persian Gulf

Mohammad Ghayyomi Jazeh,Fereidoun Forghani,S.M.E. Rahman,Myoung-Su Park,Tian Ding,Jun Wang,Joong-Hyun Park,Na-Jung Choi,Ha-Na Kim,Gwang-Hee Kim,Hyo-Jung Choi,Deog-Hwan Oh 한국식품영양과학회 2011 한국식품영양과학회 학술대회발표집 Vol.2011 No.10

Highly sensitive and selective detection of Bis-phenol A based on hydroxyapatite decorated reduced graphene oxide nanocomposites

Alam, Mohammad K.,Rahman, Mohammed M.,Elzwawy, Amir,Torati, Sri Ramulu,Islam, Mohammad S.,Todo, Mitsugu,Asiri, Abdullah M.,Kim, Dojin,Kim, CheolGi Elsevier 2017 ELECTROCHIMICA ACTA Vol.241 No.-

<P><B>Abstract</B></P> <P>A facile and cost effective chemical reduction method is employed for the preparation of reduced graphene oxide/hydroxyapatite (rGO/HAp) nanocomposites. The transmission electron microscopy images revealed that the HAp flakes are well decorated on the surface of rGO. The morphological structure of the as-synthesized rGO/HAp nanocomposites was confirmed through X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy, while the composition and thermal stability were analyzed by energy dispersive spectra and thermogravimetric analysis, respectively. Furthermore, the effect of rGO/HAp nanocomposites for the proliferation of Human Mesenchymal Stem Cell (hMSC) was performed to confirm the biocompatibility. A selective chemical sensor based on rGO/HAp modified glassy carbon electrode (GCE) for sensitive detection of Bis-phenol A (BPA) has been developed. Several important parameters controlling the performance of the BPA chemi-sensor were investigated and optimized at room conditions. The rGO/HAp/Nafion/GCE sensor offers a fast response and highly sensitive BPA detection. Under the optimal conditions, a linear range from 0.2nmolL<SUP>−1</SUP> to 2.0mmolL<SUP>−1</SUP> for the detection of BPA was observed with the detection limit of 60.0pmolL<SUP>−1</SUP> (signal-to-noise ratio, at an SNR of 3) and sensitivity of 18.98×10<SUP>4</SUP> μA.L/μmol.m<SUP>2</SUP>. Meanwhile, the fabricated chemi-sensor showed an excellent, specific and selective recognition to target BPA molecules among coexistence of other analytes in the buffer system. This novel effort initiated a well-organized way of efficient rGO/HAp/Nafion/GCE sensor development and practically analyzed the real hazardous environmental pollutants at room conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Simple chemical reduction method was used for preparation of reduced graphene oxide/hydroxyapatite (rGO/HAp) nanocomposites. </LI> <LI> The rGO/HAp nanocomposites exhibited good biocompatibility with hMSCs. </LI> <LI> Selective chemical sensor based on rGO/HAp nanocomposites was developed for detection of Bis-phenol A. </LI> <LI> The fabricated rGO/HAp/Nafion/GCE sensor exhibited good detection limit of 60pmolL<SUP>−1</SUP>. </LI> </UL> </P>

Culture Conditions for In Vitro Maturation of Abattoir Derived Oocytes of Native Zebu Cows of Bangladesh

Morshed, S.M. Niyaz,Bhuiyan, Mohammad Musharraf Uddin,Rahman, Mohammad Moshiur,Singha, Joydev Kumer,Juyena, Nasrin Sultana The Korean Society of Embryo Transfer 2014 한국동물생명공학회지 Vol.29 No.3

The objectives of the study were to determine an effective culture dish, culture duration and protein supplementation in medium for in vitro maturation (IVM) of oocytes of native zebu cows in Bangladesh. The ovaries of cows were collected from local slaughterhouse followed by aspiration of follicular fluid. The cumulus-oocyte-complexes (COCs) with more than 3 compact cumulus cell layers were cultured in tissue culture medium (TCM) 199 for maturation. The maturation of oocytes was determined by observing polar body under microscope. To determine an effective culture dish, 130 COCs derived from 48 ovaries in a well of 4-well dish and 102 COCs derived from 36 ovaries in drops covered with mineral oil within 35 mm petri dish were cultured for 24 hours. The rate of maturation of oocytes did not vary between 4-well dish ($51.3{\pm}15.0%$) and drops in petri dish ($52.4{\pm}11.6%$). To determine the effective culture duration, 185 COCs derived from 62 ovaries were cultured in drops for 18, 21, 24 and 27 hours. The rate of maturation of occytes ranged from $51.9{\pm}9.4%$ (18 hours) to $59.0{\pm}17.1%$ (27 hours) and the difference in maturation rate among different culture durations was not significant (P>0.05). To determine an effective protein supplementation, 63 oocytes from 19 ovaries were cultured separately in TCM 199 supplemented with either fetal bovine serum (FBS) or bovine serum albumin (BSA). The rate of maturation was significantly (P<0.01) higher in medium supplemented with FBS ($55.63{\pm}16.19%$) than that of BSA ($14.82{\pm}9.36%$). In conclusion, COCs of native zebu cows can be cultured for IVM either in 4-well culture dish or droplets in petri dish for 18 to 27 hours in medium supplemented with FBS.