检索结果-南通市图书馆

Rare Metals 2019年第8期38卷 754-763页

作者： Munirah A.al Messiere Department of Physics College of ScienceImam Abdulrahman Bin Faisal University

A combined study examining the temperature dependencies of Raman scattering and photoluminescence(PL)of a YBa2 Cu3 O7(YBCO)matrix doped with SiO2(12 nm;0.01 wt%.,0.10 wt%)and Zn0.95Mn0.05O(20 nm;0.02 wt%,0.10 wt%)nanoparticles was presented.X-ray diffraction(XRD)analysis confirms that both YBCO types exhibit aperovskite structure with the orthorhombic Pmmm *** microstructure was examined using environmental scanning electron microscopy(ESEM).Raman scattering and photoluminescence measurements as functions of temperature were conducted in the 77-837 K *** photoluminescence intensity is observed to decrease for the doped YBCO than for the pure YBCO,because of localized *** photoluminescence spectrum is primarily composed of three bands at 1.60,1.88,and 2.40 eV.A clearly pronounced correlation is observed between electronic and structural changes in the doped YBCO,which is due to the temperature,illumination,added oxygen or metal ions,and spectral *** PL integrated intensity as a function of the inverse temperature was simulated using the Arrhenius *** analysis reveals that the energy exchange between the different levels in the pure and doped YBCO was conducted via two vibration modes only,which are strongly linked to the oxygen and copper atoms in the YBCO *** temperature dependencies of the modes at 340 and 500 cm-1 exhibit softening with temperature increase,resulting from microstructure control,which may be due to small concentrations of Si,Zn,and Mn substitutions at the chain Cu(1)and plane Cu(2)sites.

关键词： Matrix YBa2Cu3O7 Nanoparticles Raman scattering Raman modes Photoluminescence spectra

A Krein quantization approach to Klein paradox

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2013年第11期37卷 14-19页

作者： Farrin Payandeh Toradj Mohammad Pur Mohsen fathi Zahra Gh.Moghaddam Department of Physics Payame Noor UniversityPO BOX 19395-3697 Tehran Iran Department of Physics Payame Noor UniversityTabriz Iran Department of Physics Islamic Azad University Central Tehran BranchTehran Iran

In this paper we first introduce the famous Klein tization approach and taking the negative modes into account densities could be achieved without confronting any paradox. paradox. Afterwards by proposing the Krein qu... 详细信息

关键词： Klein paradox negative energies Krein quantization

Turbine blade temperature calculation and life estimation-a sensitivity analysis

在线全文

学校读者我要写书评

暂无评论

Propulsion and Power Research 2013年第2期2卷 148-161页

作者： Majid Rezazadeh Reyhani Mohammad alizadeh alireza fathi Hiwa Khaledid Amirkabir University of Technology(Tehran Polytechnic) Tehran15875-4413Iran School of Mechanical Engineering College of EngineeringUniversity of TehranTehran4563-11155Iran K.N.T University Tehran19697-64499lran Sharif Universiry of Teclmology Tehran11365-11155Iran

The overall operating cost of the modern gas turbines is greatly influenced by thedurability of hot section components operating at high *** turbine operatingconditions,some defects may occur which can decrease hot section *** the present paper,methods used for calculating blade temperature and life are demonstrated and *** methods,a set of sensitivity analyses on the parameters affecting temperature and life ofa high pressure,high temperature turbine first stage blade is carried *** are:(1)blade coating thickness,(2)coolant inlet pressure and temperature(asa result of secondary air system),and(3)gas turbine load *** show thatincreasing thermal bamier coating thickness by 3 times,leads to rise in the blade life by *** addition,considering inlet cooling temperature and pressure,deviation in temperaturehas greater effect on blade *** of the interesting points that can be realized from theresults is that 300 hours operation at 70%load can be equal to one hour operation atbase load.

关键词： Conjugate heat transfer Life assessment Sensitivity analysis Gas turbine Blade

Practical Fast Computation of Zernike Moments

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2002年第2期17卷 181-188页

作者： al-Rawi Mohammed 杨杰 Image Processing and Pattern Recognition Institute Shanghai Jiaotong University Shanghai 200030 P.R. China

The fast computation of Zernike moments from normalized geometric moments has been developed in this paper. The computation is multiplication free and only additions are needed to generate Zernike moments. Geometric moments are generated using Hatamian's filter up to high orders by a very simple and straightforward computation scheme. Other kinds of moments (e.g., Legendre, pseudo Zernike) can be computed using the same algorithm after giving the proper transformations that state their relations to geometric moments. Proper normalizations of geometric moments are necessary so that the method can be used in the efficient computation of Zernike moments. To ensure fair comparisons, recursive algorithms are used to generate Zernike polynomials and other coefficients. The computational complexity model and test programs show that the speed-up factor of the proposed algorithm is superior with respect to other fast and/or direct computations. It perhaps is the first time that Zernike moments can be computed in real time rates, which encourages the use of Zernike momentfeatures in different image retrieval systems that support huge databases such as the XM experimental model stated for the MPEG-7 experimental core. It is concluded that choosing direct computation would be impractical.

关键词： zernike moment fast algorithm digital filter invariant pattern recognition image indexing

Determination of shear strength of steel fiber RC beams:application of data-intelligence models

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2019年第3期13卷 667-673页

作者： Abeer A.al-MUSAWI Projects and Reconstruction Department University of BaghdadBaghdadIraq

Accurate prediction of shear strength of structural engineering components can yield a magnificent information modeling and predesign *** paper aims to determine the shear strength of steel fiber reinforced concrete beams using the application of data-intelligence models namely hybrid artificial neural network integrated with particle swarm *** the considered data-intelligence models,the input matrix attribute is one of the central element in attaining accurate predictive ***,various input attributes are constructed to model the shear strength"as a targeted variable".The modeling is initiated using historical published researches steel fiber reinforced concrete beams *** variables are used as input attribute combination including reinforcement ratio(ρ%),concrete compressive strength(f′c),fiber factor(F1),volume percentage of fiber(Vf),fiber length to diameter ratio(lf/ld)effective depth(d),and shear span-to-strength ratio(a/d),while the shear strength(SS)is the output of the *** best network structure obtained using the network having ten nodes and one hidden *** final results obtained indicated that the hybrid predictive model of ANN-PSO can be used efficiently in the prediction of the shear strength of fiber reinforced concrete *** more representable details,the hybrid model attained the values of root mean square error and correlation coefficient 0.567 and 0.82,respectively.

关键词： hybrid intelligence model shear strength prediction steel fiber reinforced concrete

Device-free human micro-activity recognition method using WiFi signals

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Geo-Spatial Information Science 2019年第2期22卷 128-137,I0005页

作者： Mohammed A.A.al-qaness School of Computer Science Wuhan UniversityWuhanChina

Human activity tracking plays a vital role in human–computer *** human activity recognition(HAR)methods adopt special devices,such as cameras and sensors,to track both macro-and ***,wireless signals have been exploited to track human motion and activities in indoor environments without additional *** study proposes a device-free WiFi-based micro-activity recognition method that leverages the channel state information(CSI)of wireless *** from existed CSI-based microactivity recognition methods,the proposed method extracts both amplitude and phase information from CSI,thereby providing more information and increasing detection *** proposed method harnesses an effective signal processing technique to reveal the unique patterns of each *** applied a machine learning algorithm to recognize the proposed *** proposed method has been evaluated in both line of sight(LOS)and none line of sight(NLOS)scenarios,and the empirical results demonstrate the effectiveness of the proposed method with several users.

关键词： Human activity recognition channel state information WiFi device-free microactivity recognition machine learning

Metamaterials and plasmonics: From nanoparticles to nanoantenna arrays, metasurfaces, and metamaterials

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第4期23卷 64-75页

作者： Francesco Monticone Andrea alù Department of Electrical and Computer Engineering The University of Texas at Austin 1 University Station C0803Austin Texas 78712 USA

The rise of plasmonic metamaterials in recent years has unveiled the possibility of revolutionizing the entire field of optics and photonics, challenging well-established technological limitations and paving the way to innovations at an unprecedented level To capitalize the disruptive potential of this rising field of science and technology, it is important to be able to combine the richness of optical phenomena enabled by nanoplasmonics in order to realize metamaterial components, devices, and systems of increasing complexity. Here, we review a few recent research directions in the field of plasmonic metamaterials, which may foster further advancements in this research area. We will discuss the anomalous scattering features enabled by plasmonic nanoparticles and nanoclusters, and show how they may represent the fundamental building blocks of complex nanophotonic architectures. Building on these concepts, advanced components can be designed and operated, such as optical nanoantennas and nanoantenna arrays, which, in turn, may be at the basis of metasurface devices and complex systems. Following this path, from basic phenomena to advanced functionalities, the field of plasmonic metamaterials offers the promise of an important scientific and technological impact, with applications spanning from medical diagnostics to clean energy and information processing.

关键词： plasmonics metamaterials nanoparticles scattering

The PCDD/PCDF Dioxin Releases in the Climate of Environment of Jordan in the Period (2000-2008)

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2010年第2期19卷 182-192页

作者： Mohammed Awwad al-Dabbas Mechanical Engineering department Mutah University

Many environment problems of the full using of several categories of processing include mining,heat generators,direct combustion of forest fires,cement production,power plant,transport,medical ***/furan releases from these categories are one of these environment *** lines of reducing the PCDD/PCDF (Polychlorinated dibenzo-para-dioxins/Polychlorinated dibenzofurans) releases from these categories are *** contribution of this paper is present the identification and estimation of the latest figure of dioxin/furan releases in the climate of environment of Jordan in the period 2000-2008 from the following categories (cement,aluminum,ceramic,medical waste,power plant,land fill,ferrous and non-ferrous metals,uncontrolled combustion process (biomass burning,waste burning,accidental fires in house,transport).These finding shows the sign of growth of estimated PCDD/PCDF releases from categories which did not calculated and followed after *** result shows the highest PCDD/PCDF release from landfill fires (62.75 g TEQ/year),medical waste (8.8264 g TEQ/year),and transport (3.0145 g TEQ/year).Jordan seeks by next years,a reduction in total releases of dioxins and furans from sources resulting from human *** challenge will apply to the aggregate of releases to the air nationwide and of releases to the water within the Jordan *** should conduct air monitoring for dioxin in order to track fluctuations in atmospheric deposition levels.

关键词： Jordan transport sector PCB dioxin & furan POP PCDD/PCDF power plant biogas

Changing patterns of hepatitis A prevalence within the Saudi population over the last 18 years

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2008年第48期14卷 7371-7375页

作者： Faleh al Faleh Suliman al Shehri Saleh al Ansari Mohammed al Jeffri Yaqoub al Mazrou Ahmad Shaffi Ayman A Abdo Department of Medicine College of Medicine King Saud University Ministry of Education Ministry of Health Department of Community Medicine College of Medicine King Saud University

AIM： To determine the seroprevalence of Hepatitis A （HAV） amongst Saudi children and compare it with previously reported prevalence data from the same population. METHODS： A total of 1357 students were randomly selected between the ages of 16 and 18 years （689 males and 668 females） from three different regions of Saudi Arabia （Madinah, AI-Qaseem, and Aseer） and tested for ***： The overall prevalence of anti-HAV-IgG among the study population was 18.6%. There was no difference between males and females but there was a significant difference in the seroprevalence （P = 0.0001） between the three different regions, with Madinah region showing the highest prevalence （27.4%）. When classified according to socioeconomic status, lower class students had a prevalence of 36.6%, lower middle class 16.6%, upper middle class 9.6%, and upper class 5.9% （P = 0.0001）. Comparing the current study results with those of previous studies in 1989 and 1997 involving the same population, there was a marked reduction in the overall prevalence of HAV from 52% in 1989, to 25% in 1997, to 18.6% in 2008 （P 〈 0.0001）.CONCLUSION： Over the last 18 years, there has been a marked decline in the prevalence of HAV in Saudi children and adolescents. The current low prevalence rates call for strict adherence to vaccination policies in high-risk patients and raises the question of a universal HAV vaccination program.

关键词： Hepatitis A Saudi Arabia Epidemiology Prevalence Serology

Royal-jelly-based apitherapy can attenuate damages to male reproductive parameter following nicotine administration

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Animal Models and Experimental Medicine 2022年第2期5卷 133-140页

作者： Mahsa Nazar-Zadeh Cyrus Jalili Amene Nikgoftar fathi ali Ghanbari Mitra Bakhtiari Department of Anatomical Sciences Medical SchoolKermanshah University of Medical SciencesKermanshahIran Medical Biology Research Center Kermanshah University of Medical SciencesKermanshahIran Department of Anatomical Sciences Medical SchoolArak University of Medical SciencesArakIran

Background:Nicotine administration can generate severe oxidative stress and lipid *** jelly,with its antioxidant properties,acts as a scavenger of reactive oxygen *** study describes the apitherapy effects of royal jelly on testicular damage following nicotine ***:Forty-eight male BalB/c mice were divided into 8 groups(n=6):saline,3 different doses of royal jelly(100,150,and 200 mg/kg body weight(BW)per day),nicotine(1.5 mg/kg),and 3 different groups of Nic+Roy(1.5 mg/kg of Nic+100,150,and 200 mg/kg BW per day of royal jelly).Nicotine was administrated intraperitoneally,and royal jelly was prescribed orally for 10 consecutive *** levels of hormones(testosterone,luteinizing hormone,and follicle-stimulating hormone),total antioxidant capacity,nitric oxide(NO)status,malondialdehyde levels,sperm DNA fragmentation,sperm parameters,histopathological changes(H&E staining),immunohistochemistry against apoptotic proteins,and gene expression of Bcl-2,p53,Caspase-3,and Nrf2(real-time PCR)were assessed to evaluate the molecular and histological ***:Hormone levels,sperm parameters,and status of antioxidants were decreased significantly(pal jelly treatment normalized hormonal and antioxidant characteristics,decreased apoptotic gene expression,increased Nfr2 gene expression,and restored histopathological alteration to the physiological status significantly(pal jelly upregulates the antioxidant status,inhibits the mitochondrialdependent apoptosis pathway,and increases the rate of *** therapeutic agent effectively protected the testis against nicotine-associated damages by antioxidant and anti-apoptotic effects.

关键词： antioxidant apitherapy apoptosis damage male nicotine reproduction royal jelly testis