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Search Results: 1 - 10 of 120108 matches for " Wang Siji "
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Active Elastic Support/Dry Friction Damper with Piezoelectric Ceramic Actuator
Liao Mingfu,Song Mingbo,Wang Siji
Shock and Vibration , 2014, DOI: 10.1155/2014/712426
Abstract: The basic operation principle of elastic support/dry friction damper in rotor system was introduced and the unbalance response of the rotor with elastic support/dry friction damper was analyzed theoretically. Based on the previous structure using an electromagnet as actuator, an active elastic support/dry friction damper using piezoelectric ceramic actuator was designed and its effectiveness of reducing rotor vibration when rotor traverses its critical speed and blade-out event happened was experimentally verified. The experimental results show that the active elastic support/dry friction damper with piezoelectric ceramic actuator can significantly reduce vibration in rotor system; the vibration amplitude of the rotor in critical speed region decreased more than 2 times, and the active damper can protect the rotor when a blade-out event happened, so the rotor can traverse the critical speed and shut down smoothly. In addition, the structure is much simpler than the previous, the weight was reduced by half and the power consumption was only 5?W. 1. Introduction Rotors in aircraft engines mostly operate above the first critical speed, some even over second and third critical speeds. They must traverse their critical speeds frequently in the operation. When a blade-out event happens in an engine, it must be shut down immediately [1]. However in this case, the rotor will vibrate violently while traversing the critical speed region due to the excessive unbalance. This could cause further damage to the engine [1–3]. In Certification Specifications for Large Airplanes CS-25 [4], some clauses about aircraft engine rotor are as follows. “Design precautions must be taken to minimize the hazards to the airplane in the event of an engine rotor failure.” “There must be means for stopping the rotation of any engine individually in flight.” This is a crucial challenge to the design of aircraft engines. In order to deal with abovementioned problems, effective damping must be incorporated into rotor systems. It has been proven theoretically and experimentally that as a new rotor vibration damper, the elastic support/dry friction damper can significantly attenuate the vibration amplitude of rotor system in the critical speed region [5–7]; moreover, it is convenient to be controlled by adjusting control voltage [8–11]. However, due to its oversized electromagnetic actuator, the application of such a damper in aircraft engines will be restricted. In recent years, smart materials have received more and more attention in structure vibration control. It has brought some new
Blank Holder Force Control System Driven by Servo-Motor  [PDF]
Siji Qin, Li Yang, Bing Yang
Intelligent Control and Automation (ICA) , 2011, DOI: 10.4236/ica.2011.24051
Abstract: Blank holder force (BHF) control is used to prevent wrinkles of sheet metal in deep drawing process. Based on a novel conception of BHF control technique driven by servo-motor, a new BHF device with six-bar linkage mechanism has been designed and manufactured. Whole control system of the new BHF technique was developed, and the basic structure of the hardware configuration of the system was given. Software analysis, implementation and division of the functional modules have been done. Also, the control software in data acquisition and processing module has been developed in the relevant technology of the BHF control system for the requirements of real-time, stability and accuracy. By the new BHF device combined with the hardware and the software system, the BHF can be regulated accurately variation with the predefined BHF profile in deep drawing process.
Re-examination of Trends Related to Tropical Cyclone Activity over the Western North Pacific Basin

SONG Jinjie,HAN Juejing,LI Siji,WANG Yuan,WU Liguang,

大气科学进展 , 2011,
Abstract: In order to re-examine some trends related to tropical cyclones (TCs) over the western North Pacific since 1949, the unreliable maximum sustained wind (Vmax) recorded in the 1949--1978 TC best-track data from the Shanghai Typhoon Institute was modified based on the wind--pressure relationships (WPRs) in this study. Compared to the WPR scheme based on the cyclostrophic balance, the WPR scheme based on the gradient balance could give a better fit to TCs under higher wind speeds and could introduce smaller estimated errors for TCs locating at higher latitudes as well as TCs landing on the continent. After the Vmax modification based on minimum sea-level pressure and TC center latitude, the revised annual number of category 4--5 typhoons shows no long-term trend, while the potential destructiveness measured by power-dissipation index decreases slightly, and this trend is not significant in the period 1949--2008.
Effects of phosphate removal by thermal- and acid-activated ferric and alum water treatment residuals

GAO Siji,WANG Changhui,PEI Yuansheng,

环境科学学报 , 2012,
Abstract: 探讨了酸活化和热活化方式对给水厂废弃铁铝泥(ferric and alum water treatment residuals,FARs)吸附磷能力的影响.结果表明,酸活化和热活化均能提高FARs的磷吸附能力,其中经2 mol·L-1 HCl酸活化的FARs(AH2.0-FARs)和300 ℃热活化的FARs(H300-FARs)取得最好的磷吸附效果.结合SEM和XRD表征技术对活化机制分析得知,两种活化方式均会使FARs变得疏松、多孔,从而提高FARs对磷的吸附能力.Langmuir和Freundlich两种模型均可很好 地反映活化前后FARs的等温吸附过程,FARs对磷的理论饱和吸附量由活化前的20.48 mg·g-1分别增加到22.86 mg·g-1(AH2.0-FARs)和29.66 mg·g-1(H300-FARs).低pH值有利于FARs对磷的吸附.此外,解吸附实验结果表明活化后的FARs能够更好地固定磷.因此,活化后的FARs是一种相对更好的磷的吸附材料.
Hysteresis of Isotherms of Mixed Monolayers of N-Octadecyl-N′-phenylthiourea and Stearic Acid at Air/Water Interface
Siji Sudheesh,Jamil Ahmad,Girija S. Singh
ISRN Physical Chemistry , 2012, DOI: 10.5402/2012/835397
Evaluation of High Resolution Melting analysis as an alternate tool to screen for risk alleles associated with small kidneys in Indian newborns
Ashwini Raghavendra, Annes Siji, TS Sridhar, Kishore Phadke, Anil Vasudevan
BMC Nephrology , 2011, DOI: 10.1186/1471-2369-12-60
Abstract: High resolution melting analysis was performed on 75 DNA samples that were previously sequenced for the known polymorphisms in RET (rs1800860), PAX2 (rs11190688) and ALDH1A2 (rs7169289) genes. The SNPs were G > A transitions in RET and PAX2 and A > G in ALDH1A2 gene. A blinded assessment was performed on these samples for evaluation of the HRM technique as compared to sequencing.Each variant had a unique melt curve profile that was reproducible. The shift in melting temperature (Tm) allowed visual discrimination between the homozygous alleles (major and minor) in all three genes. The shape of the melting curve as compared to the major allele homozygous curve allowed the identification of the heterozygotes in each of the three SNPs. For validation, HRM was performed on 25 samples for each of the three SNPs. The results were compared with the sequencing results and 100% correct identification of the samples was obtained for RET, PAX2, and ALDA1H2 gene.High Resolution Melting analysis is a simple, rapid and cost effective technique that could be used in a large population to identify babies with the risk alleles. These high risk children could be followed up for early detection of hypertension and acquired renal dysfunction.Single nucleotide polymorphisms (SNPs) are the most common form of sequence variation in the human genome. Large scale studies have shown that these single base variations in DNA sequences affect the development of some diseases and also provide the genetic bases for individual variations in response to pathogens, drugs and vaccines [1,2]. Therefore, the identification of SNPs may be seen as a component of individualized risk assessment.Recently, common variants of three human genes involved in kidney development- RET (rs1800860), PAX2 (rs11190688) and ALDH1A2 (rs7169289) have been reported to be associated with variation in renal volume (surrogate marker for nephron numbers) and function, in a cohort of Montreal newborns [3-5]. Understanding the ro
S. Nishanth Kumar*, J. V. Siji, Bala Nambisan and C. Mohandas
International Journal of Pharmaceutical Sciences and Research , 2012,
Abstract: Candida albicans is one of the most important fungi associated with oral candidiasis and the treatment of this fungi is a serious problem today because of the resistance of these fungi against conventionally used drugs. So, there is an urgent need of alternative antifungal substances especially from the natural sources. The study was conducted to examine the MFC and time kill activity of two stilbenes [3, 4', 5-trihydroxystilbene (1) and 3,5-dihydroxy-4-isopropylstilbene (2)] purified from a bacterium associated with entomopathgenic nematode against C. albicans. The activity was also compared to amphotericin B. The cytotoxicity of stilbenes was also tested against normal human cell lines (L231 lung epithelial and FS normal fibroblast). Results showed that stilbenes was effective against C. albicans with MIC and MFC of 64 and 128 μg/ml for compound 1 and 32 and 64 μg/ml for compound 2. The time kill assay of stilbenes against C. albicans was more effective than amphotericin B. No cytotoxicity was recorded for stilbenes upto 200 μg/ml. The strong antifungal activity and low cytotoxicity of stilbenes make it a promising agent for the treatment of Candida.
S. Nishanth Kumar,J. V. Siji,R. Ramya,Bala Nambisan
Journal of Microbiology, Biotechnology and Food Sciences , 2012,
Abstract: A specific symbiotic Bacillus sp. isolated from a rhabditid entomopathogenic nematode, Rhabditis (Oscheius) sp. was found to produce a large number of bioactive compounds. The present study was conducted to determine the effect of carbon and nitrogen sources for the production of antimicrobial substances by Bacillus sp. The yield of the crude antimicrobial substances and antimicrobial activity against the test microorganism also differed significantly when carbon and nitrogen sources in the fermentation media were changed. The antimicrobial activity was significantly high in yeast extract plus fructose [Pencillium expansum (46.5±2.12 mm) and Escherichia coli (42±1.41 mm)] and yeast extract plus maltose followed by meat peptone plus fructose. Antimicrobial activity was significantly reduced with malt extract irrespective of its carbon sources. HPLC analysis of the crude antimicrobial substances revealed different peaks with different retention time indicating that they produced different compounds. When the carbon source was not included in the fermentation media, the antimicrobial production was substantially reduced. The results indicate that carbon source in the fermentation media plays a vital role in the production of antimicrobial substances. It is concluded that yeast extract and fructose as nitrogen and carbon sources produced maximum activity.
Photoelectrocatalysis and degradation of Tracid Bordeaux by TiO2 film coating electrode

Zhou Siji,Zou Hua,Dai Lin,

环境工程学报 , 2013,
Abstract: Photoelectrocatalysis reactor was designed and assembled to treat Tracid Bordeaux wastewater, titanium plate coated with TiO2 thin film by sol-gel method was used as electrodes. The synergy of photo-electric reaction and the effects of initial dyes concentration, voltage, pH and electrolyte concentration on decoloration were discussed. The result shows that photochemical catalysis and electrochemical oxidation have cooperative effects. The decoloring rates of ultraviolet light catalysis and electro-catalysis to tracid bordeaux were 44.27% and 13.12%, respectively. However, the decoloring rate of photoelectrocatalysis (ultraviolet light plus voltage of 10 V) reached as high as 77.18%. The low initial concentration, moderate voltage and alkaline pH led to higher decoloring rate of tracid bordeaux wastewater. The electrolyte was beneficial to decoloration. The higher the electrolyte concentration was, the higher decoloring rate would be.
Himaja M,Siji Rajan,Karigar A.A,Ramana M.V
International Research Journal of Pharmacy , 2011,
Abstract: The N-methyl derivative of Cherimolacyclopeptide E cyclo[Phe-(Dimethyl)Tyr-Pro-Gly-Leu-Gly] was synthesized using solution phase peptide synthesis. The synthesized compound was characterized by spectral data and was evaluated for anthelmintic and insecticidal activities. The compound exhibited potent anthelmintic activity as compared to the standard drug mebendazole.
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