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Editor's Letter

The World of Chinese 2024年第1期 1-1页

作者： sam Davies 不详

China is an education powerhouse. The country’s universities produced nearly 12 million graduates last year, while 18 million teachers in public schools prepared students for exams. But changes are afoot in this giant education sector. This issue’s cover story delves into new trends and strains impacting teachers, students, and universities.

关键词： while education Letter

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Dancing with a Star

China Weekly 2024年第7期 62-62页

作者： sam Duckett 不详

It was just an ordinary day in Beijing when I got a message from my daughter's kindergarten about an upcoming school dance *** first,I thought,"How delightful,I can't wait to see her perform!"To my dismay,I discovered... 详细信息

关键词： daughter dis ordinary

OSCILLATION CRITERIA FOR SECOND ORDER NONLINEAR DYNAMIC EQUATIONS WITH p-LAPLACIAN AND DAMPING

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Acta Mathematica Scientia 2013年第4期33卷 975-988页

作者： taher S.HASSAN Qingkai KONG Department of Mathematics Faculty of Science Mansoura University Department of Mathematics Northern Illinois University

This paper concerns the oscillation of solutions of the second order nonlinear dynamic equation with p-Laplacian and damping（r（t）φ（x^△（t））^△＋p（t）φα（x^△α（t）＋q（t）f（xδ（t））=0on a time scale T which is unbounded above. Sign changes are allowed for the coefficient functions r, p and q. Several examples are given to illustrate the main results.

关键词： oscillation dynamic equations time scales

An efficient hybrid evolutionary optimization algorithm based on PSO and SA for clustering

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第4期10卷 512-519页

作者： taher NIKNAM Babak AMIRI Javad OLAMAEI Ali AREFI Electronic and Electrical Engineering Department Shiraz University of TechnologyShirazIran Information Technology Department Islamic Azad University-Fars Science and Research BranchShiraz Iran Technical Engineering Department Islamic Azad University-South Tehran BranchTehran Iran Power Engineering Group Department of Electrical and Computer Engineering Tarbiat Modares UniversityTehran Iran

The K-means algorithm is one of the most popular techniques in clustering. Nevertheless, the performance of the Kmeans algorithm depends highly on initial cluster centers and converges to local minima. This paper proposes a hybrid evolutionary programming based clustering algorithm, called PSO-SA, by combining particle swarm optimization (PSO) and simulated annealing (SA). The basic idea is to search around the global solution by SA and to increase the information exchange among particles using a mutation operator to escape local optima. Three datasets, Iris, Wisconsin Breast Cancer, and Ripley's Glass, have been considered to show the effectiveness of the proposed clustering algorithm in providing optimal clusters. The simulation results show that the PSO-SA clustering algorithm not only has a better response but also converges more quickly than the K-means, PSO, and SA algorithms.

关键词： Simulated annealing (SA) Data clustering Hybrid evolutionary optimization algorithm K-means clustering Parti-cle swarm optimization (PSO)

Synthesis of Gd_2O_3 nanoparticles:using bulk Gd_2O_3 powders as precursor

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Rare Metals 2015年第8期34卷 540-545页

作者： taher Yousefi Meisam Torab-Mostaedi Mostafa Ghasemi Amir Ghadirifar Nuclear Fuel Cycle Research School Nuclear Science andTechnology Research Institute

Gd2O3nanoparticles were synthesized from the commercial bulk Gd2O3 powders via a simple electrochemical method. The synthesized powders were characterized by means of X-ray powder diffraction(XRD),scanning electron microscopy(SEM), transmission electron microscopy(TEM) and Fourier transform infrared(FTIR) spectroscopy. The effects of solution p H on the morphological features of the sample were studied. The strategy developed in this study offers significant advantages for the synthesis of Gd2O3 nanoparticles from the bulk Gd2O3 powders compared with the conventional routes. From SEM observations, the size of the Gd2O3 nanoparticles is estimated to be significantly smaller than70 nm.

关键词： Gd2O3 Nanoparticles Electro-deposition Nanostructu

Thermal Conductivity of Low Density Polyethylene Foams Part I: Comprehensive Study of Theoretical Models

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Journal of Thermal Science 2019年第4期28卷 745-754页

作者： REZGAR Hasanzadeh taher Azdast ALI Doniavi RICHARD Eungkee Lee Mechanical Engineering Department Urmia University

Polymeric foams are one of the most applicable thermal-insulation materials due to their low thermal conductivity,high mechanical properties,and low *** of thermal-insulation performance of polymeric foams needs a theoretical model in order to predict the overall thermal *** far,several theoretical approaches are presented in this regard but to the best knowledge of the authors,there is no comprehensive investigation on comparing the proposed ***,the study of validity of the theoretical models in comparison with the experimental results is one of the main goals of the present *** density polyethylene(LDPE)foams are selected as the case study due to the wide application *** models to predict the overall conductivity of the foam based on conduction through the combined gas and solid phases(λgs)as well as radiation thermal conductivity(λr)are *** results indicate that the best model is a model in whichλgs is calculated using Gibson and Ashby model andλr is obtained using Williams and Aldao model based on the root mean square(RMS)*** results show that the theoretical error of this model is smaller than 10%.

关键词： thermal conductivity polymeric foams theoretical models radiation

Simultaneous extraction and preconcentration of copper,silver and palladium with modified alumina and their determination by electrothermal atomic absorption spectrometry

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Chinese Chemical Letters 2014年第4期25卷 649-654页

作者： Mohammad Ali taher Zahra Daliri Hamid Fazelirad Department of Chemistry Shahid Bahonar University of Kerman Department of Polymer Science and Research BranchIslamic Azad University Young Researchers Society Shahid Bahonar University of Kerman

In the present work, an easy solid phase extraction method using alumina modified with polyethylenimine as a new adsorbent was applied to the simultaneous extraction of copper, silver, and palladium ions prior to their determination with electrothermal atomic absorption spectrometry. The analytical procedure involved the complex formation of these cations with polyethylenimine as a chelating agent in buffer media of pH 7.0. Under the optimum conditions, a preconcentration factor of 200, 150, and 200, precision of ~5.4%, ＋4.7%, and ＋5.2% and linear calibration ranges of 15.0-140, 4.0-93, and 7.5-125 ng/L （in original solution） for Cu, Ag, and Pd were obtained, respectively. Also detection limits of 3.9,1.1, and 2.0 ng/L were obtained for Cu, Ag, and Pd, respectively. The proposed method was applied to the determination of copper, silver, and palladium in some real samples with satisfactory results.

关键词： Polyethylenimine Solid phase extraction Copper Silver Palladium Electrothermal atomic absorptionspectrometry

Influence of mulching and tree shelters on 4-year survival and growth of zeen oak (Quercus canariensis) seedlings

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Journal of Forestry Research 2019年第1期30卷 129-141页

作者： taher Mechergui Marta Pardos Douglass F.Jacobs Facultédes Sciences de Bizerte Laboratoire des Ressources Sylvo-Pastorales (Institut Sylvo-Pastoral de Tabarka) Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (INIA) Centro de Investigacion Forestal Department of Forestry and Natural Resources Hardwood Tree Improvement and Regeneration Center Purdue University

We assessed the effect of mulching and tree shelters on the establishment and early growth of zeen oak(Quercus canariensis Willd.) during the first 4 years after planting in Northwestern Tunisia. Five mulch types(Italian Stone Pine(Pinus pinea L.), Lentisk(Pistacia lentiscus L.),and a combination of Italian Stone Pine and Lentisk(organic mulches), gravel(inorganic mulch) and control), and three tree shelter types(non-vented and vented tree shelters, and control) were tested. An increase in the number of internodes occurred under the gravel mulch, while a reduction in survival was found for the lentisk mulch. Tree shelters had no effect on survival, but increased mean height growth and reduced mean diameter growth during the 4 years(excepting a non-significant effect for vented tree shelter at year four). Comparison of the annual shoots and growth units(GU) between sheltered and unsheltered plants according to year of formation revealed two growth phases. In first phase, shoots were totally or partially inside the shelters; mean length of annual shoots and GU were greater for sheltered plants. The second phase was characterized by shoots emerging from shelters; mean length of annual shoots and GU were similar for all plants, with or without tree shelters. Results suggest that the use of tree shelters, particularly vented shelters, could contribute to the improvement of the artificial regeneration of zeen *** use of mulching alone or in combination with tree shelters did not improve zeen oak performance in the field.

关键词： Zeen oak Mulching Tree shelters Plantation Survival rate Growth

Duffing Oscillator’s Vibration Control under Resonance with a Negative Velocity Feedback Control and Time Delay

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Sound & Vibration 2021年第3期55卷 191-201页

作者： Y.A.Amer taher A.Bahnasy Department of Mathematics Faculty of ScienceZagazig UniversityZagazigEgypt Department of Engineering Physics and Mathematics Faculty of EngineeringTanta UniversityTantaEgypt

An externally excited Duffing oscillator under feedback control is discussed and analyzed under the worst resonance *** time scales method is applied for this system to find analytic solution with the existence and nonexistence of the time delay on control *** appropriate stability analysis is also performed and appropriate choices for the feedback gains and the time delay are found in order to reduce the amplitude *** response curves are involved to show and compare controller *** addition,analytic solutions are compared with numerical approximation solutions using Rung-Kutta method of fourth order.

关键词： Non-linear dynamical system multiple time scales method active feedback controller time delay