Nonlinear saturation controller for vibration supersession of a nonlinear composite beam

Y. S. Hamed,Y. A. Amer 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.8

In this paper, a study for nonlinear saturation controller (NSC) is presented that used to suppress the vibration amplitude of a structuraldynamic model simulating nonlinear composite beam at simultaneous sub-harmonic and internal resonance excitation. The absorberexploits the saturation phenomenon that is known to occur in dynamical systems with quadratic non-linearities of the feedback gain and atwo-to-one internal resonance. The analytical solution for the system and the nonlinear saturation controller are obtained using method ofmultiple time scales perturbation up to the second order approximation. All possible resonance cases were extracted at this approximationorder and studied numerically. The stability of the system at the worst resonance case ( 2 sw W = andws = 2wc ) is investigated usingboth frequency response equations and phase-plane trajectories. The effects of different parameters on the system and the controller arestudied numerically. The effect of some types of controller on the system is investigated numerically. The simulation results are achievedusing Matlab and Maple programs.

Associations between Polymorphisms in Phase II Enzymes and Circulating Sex-Steroid Hormones in White Postmenopausal Women

( Andrea Y Arikawa ),( Hamed Samavat ),( Mindy S Kurzer ) 대한폐경학회 2021 대한폐경학회지 Vol.27 No.2

Objectives: The purpose of this cross-sectional study was to examine whether single nucleotide polymorphisms (SNPs) in enzymes that metabolize sex steroid hormones were associated with the blood levels of these hormones in postmenopausal women and if the use of menopausal hormone therapy (MHT) could modify this association. Methods: Baseline data were collected from 932 postmenopausal women enrolled in the Minnesota Green Tea Trial. Participants filled out a questionnaire about their demographics, lifestyle factors, and medical and reproductive history. Free, bioavailable, and total serum levels of reproductive hormones were measured through liquid chromatography/tandem mass spectrometry. For genotyping of UGT1A1 (rs10928303), UGT1A4 (rs10929301, rs11673726), UGT1A6 (rs1105879, rs2070959, rs6759892), UGT1A8 (rs10167119), UGT2B7 (rs7439366), and SULT1A1 (rs9282861, rs1968752), mass spectrometry based on multiplex methods and TaqMan assays were performed. Adjusted linear models were fit to assess the associations between SNPs and blood hormones using age, body mass index (BMI), and MHT as covariates. Results: The mean age was 59.8 years, and the mean BMI was 25.1 kg/m2. Past or recent use of MHT was reported by 41.2% of the participants. SNPs in SULT1A1 (rs1968752 and rs9282861) and UGT1A4 (rs11673726) genes were significantly associated with estrone levels, whereas SNPs in UGT1A6 (rs6759892) and UGT1A8 (rs10167119) genes were significantly associated with bioavailable estradiol levels. Conclusions: There was no evidence that MHT use modified the association between SNPs and sex-steroid hormone levels; however, further studies are needed to establish the potential clinical significance of UGT1A4 (rs11673726), UGT1A6 (rs6759892), and UGT1A8 (rs10167119) SNPs and the modulation of hormone levels in postmenopausal women.

풍력발전기를 위한 상태 모니터링 기술

자파르 하미드(Hameed, Z.),홍영선(Hong, Y.S.),안성훈(Ahn, S.H.),조영만(Cho, Y.M.),송철기(Song, C.K.),박종포(Park, Jong-Po) 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.06

Renewable energy sources such as wind energy is copiously available without any limitation. Wind turbines are used to tap the potential of wind energy which is available in millions of megawatt. Reliability of wind turbine is critical to extract this maximum amount of energy from the wind. We reviewed different techniques, methodologies, and algorithms developed to monitor the performance of wind turbine as well as for an early fault detection to keep away the wind turbines from catastrophic conditions due to sudden breakdowns. To keep the wind turbine in operation, implementation of Condition Monitoring System (CMS) is paramount, and for this purpose ample knowledge of these types of system is mandatory. So, an attempt has been made in this direction to review maximum approaches related to CMS in this piece of writing.

집속이온빔(FIB)로 가공된 10마이크로미터 급의 마이크로 밀링 툴의 제작

김충수(C. S. Kim),추원식(W. S. Chu),안성훈(S. H. Ahn),장동영(D. Y. Jang),Jitendra Kumar Pandy,정범석(B. S. Jung),Zafar Hameed 한국정밀공학회 2008 한국정밀공학회 학술발표대회 논문집 Vol.2008 No.6월

A review on waste-derived adsorbents from sugar industry for pollutant removal in water and wastewater

Anastopoulos, I.,Bhatnagar, A.,Hameed, B.H.,Ok, Y.S.,Omirou, M. Elsevier 2017 Journal of molecular liquids Vol.240 No.-

<P>Sugar industry generates a significant amount of by-products (such as sugar beet pulp (SBP), sugarcane bagasse (SCB)) and their handling and management is a matter of great concern. Among their uses such as fuel and fertilizer, the valorization of biowastes from sugar industry as adsorbents for the removal of various aquatic pollutants presents promising features in terms of cost reduction for waste disposal and environmental protection. This review article deals with the use of sugar waste based materials used as adsorbents in water treatment. For this purpose, isotherms, kinetics, desorption and thermodynamic information are thoroughly presented. Moreover, many parameters which control the adsorption process, such as the effect of initial concentration, initial solution pH, contact time, temperature and adsorbent's dosage, are also discussed in detailed. The performance of the adsorbents largely depends on the type of pollutants and experimental conditions. Surface modification with chemicals greatly enhance the removal efficiency with favorable kinetics and adsorption mechanism. (C) 2017 Elsevier B.V. All rights reserved.</P>

Assessment of radioactivity levels and radiation hazards in building materials in Egypt

Ahmed E. Abdel Gawad,Mohamed Y. Hanfi,Mostafa N. Tawfik,Mohammed S. Alqahtani,Hamed I. Mira Korean Nuclear Society 2024 Nuclear Engineering and Technology Vol.56 No.2

Different degrees of natural radioactivity found in quartz can have negative consequences on health. Quartz vein along the investigated Abu Ramad area, Egypt, had its natural radioactivity assessed. The HPGe spectrometer was used to determine the role played by the radionuclides ²³⁸U, ²³²Th, and ⁴⁰K in the gamma radiation that was emitted, and the results showed that these concentrations are 484.64 ± 288.4, 36.8 ± 13.1 and 772.2 ± 134.6 Bq kg^-1 were higher than the corresponding reported global limits of 33, 45, and 412 Bq kg^-1 for each radionuclide (²³⁸U, ²³²Th, and ⁴⁰K). Among the radiological hazard parameters, the excess lifetime cancer risk (ELCR) is estimated and it's mean value of ELCR (1.2) is higher than the permissible limit of 0.00029. The relationship between the radionuclides and the associated radiological hazard characteristics was investigated based on multivariate statistical methods including Pearson correlation, principal component analysis (PCA), and hierarchical cluster analysis (HCA). According to statistical research, the radioactive risk of quartz is primarily caused by the ²³⁸U, ²³²Thand ⁴⁰K. Finally, applying quartz to building materials would pose a significant risk to the public.

Vibration suppression in ultrasonic machining described by non-linear differential equations

M. M. Kamel,W. A. A.El-Ganaini,Y. S. Hamed 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.8

Vibrations are usually undesired phenomena as they may cause damage or destruction of the system. However, sometimes they are desirable, as in ultrasonic machining (USM). In such case, the problem is a complicated one, as it is required to reduce the vibration of the machine head and have reasonable amplitude for the tool. In the present work, the coupling of two non-linear oscillators of the tool holder and tool representing ultrasonic cutting process is investigated. This leads to a two-degree-of-freedom system subjected to multi-external excitation force. The aim of this work is to control the tool holder behavior at simultaneous primary and internal resonance condition and have high amplitude for the tool. Multiple scale perturbation method is applied to obtain a solution up to the second order approximations. Other different resonance cases are reported and studied numerically. The stability of the system is investigated applying both phase-plane and frequency response techniques. The effects of the different parameters of the tool on the system behavior are studied numerically. Comparison with the available published work is reported.

Wear properties of ECAP-processed ultrafine grained Al-Cu alloys

Abd El Aal, M.I.,El Mahallawy, N.,Shehata, F.A.,Abd El Hameed, M.,Yoon, E.Y.,Kim, H.S. Elsevier Sequoia 2010 Materials science & engineering. properties, micro Vol.527 No.16

The wear properties of equal channel angular pressing (ECAP) Al-2, 3 and 5%Cu alloys under dry sliding conditions using different sliding distances and loads were investigated by pin-on-disc dry sliding wear tests. The wear mass loss decreased remarkably as the number of ECAP passes and Cu content increased, being affected more by the sliding distance than by the applied load under the experimental conditions. The wear mechanism was observed to be adhesive and delamination initially, and an abrasive mechanism also appeared as the sliding distance increased. The analysis of the wear surface indicates a transfer of Fe from the rotating disc to the Al-Cu alloy pin with increases in the sliding distance, the applied load, the number of passes and the copper content.