675 research outputs found
Teachers’ assessment of Chinese language syllabus at secondary schools in Malaysia
The study was conducted based on the conceptual framework of CIPP to evaluate teachers’ views on the Chinese Language Syllabus at lower secondary schools in Selangor state, Malaysia. The study involved 111 teachers from Chinese schools from different backgrounds. All sample subjects were randomly selected from ten districts of Selangor. Questionnaires were used as the research instruments and research questions used the Likert scale for measurement. The data were analyzed using SPSS. The results showed the continuation of syllabus from Form I to Form III, as well as consistency with the textbook contents. The findings also showed that teachers did not know clearly the three main domains in the syllabus and were unclear about the objective of the syllabus. Results of t-test and ANOVA test showed no significant differences in the evaluation of teachers in general despite the teachers’ different backgrounds. Teachers recommended that they should be given more opportunities in curriculum planning. In conclusion, the Chinese language syllabus is appropriate and the three main domains of interpersonal domain, information domain and maintenance of aesthetics domain should be simplified
Real-Time Substructure Tests and Numerical Simulation of Mechanical Characteristics of Natural Rubber-Laminated Bearings
Natural rubber lamination is a kind of seismic isolation of bearings often used in civil engineering. The advantage of laminated bearings is large vertical stiffness and small lateral stiffness. In seismic regions, structural periods would be extended and the effect of seismic forces can be lowered using bearings. In previous tests, the static cyclic loading method was mainly used that failed to take account of the loading rate. The real-time substructure testing is proposed to simulate true seismic loads. This testing and test setup were first introduced, and the effect of the loading rate was studied. Then the effects of vertical pressure and peak acceleration of ground motion were studied. At last the test results were simulated by the finite element method, and an accurate method to calculate seismic responses of bridges with laminated bearings was proposed.Ламинирование природным каучуком – один из видов сейсмической изоляции опор, часто используемый в гражданском строительстве. Ламинированные опоры характеризуются высокой вертикальной жесткостью и низкой поперечной жесткостью. В сейсмических регионах сроки строительства увеличиваются, а влияние сейсмических сил может быть уменьшено за счет применения подобных опор. До сих пор основой для испытаний служил статический метод циклического нагружения, не позволявший учитывать его скорость. Предложен метод испытания в реальных условиях эксплуатации, моделирующий истинные сейсмические нагрузки. Внедрены метод испытаний и испытательная установка, изучено влияние скорости нагружения, вертикального давления и пикового ускорения движения грунта. Выполнено моделирование результатов испытания с помощью метода конечных элементов. Предложен точный метод расчета сейсмических характеристик мостов с опорами, ламинированными природным каучуком
A modified layer-removal method for residual stress measurement in electrodeposited nickel films
Combining the traditional layer-removal method with a cantilever beam model, a modified layer-removal method is developed and used to measure residual stress in single and multi-layer electrodeposited nickel films with thickness of 2.5 μm. The out-of-plane displacement of the free tip of a cantilever beam is measured by the digital speckle correlation method. The results show that residual stress in a single semimat nickel film is compressive, while in a multi-layer system composed of dark, semimat and holophote nickel, residual stress in the surface layer is tensile. Residual stress decreases gradually with the increase of etching depths of single and multi-layer films. These findings are in qualitative agreement with nanoindentation tests, which confirms the reliability of the modified layer-removal method
Performance of Sn–3.0Ag–0.5Cu composite solder with TiC reinforcement: physical properties, solderability and microstructural evolution under isothermal ageing
This paper is focused on the effect of TiC nano-reinforcement that was successfully introduced into a SAC305 lead-free solder alloy with different weight fractions (0, 0.05, 0.1 and 0.2 wt%) through a powder-metallurgy route. Actual retained ratios of TiC reinforcement in composite solder billets and solder joints were quantitatively analysed. The obtained SAC/TiC solders were also studied extensively with regard to their coefficient of thermal expansion (CTE), wettability and thermal properties. In addition, evolution of interfacial intermetallic compounds (IMCs) and corresponding changes in mechanical properties under thermal ageing were investigated. Only about 10%–30% of initial TiC nanoparticles added were found retained in the final composite solder joints. With an appropriate addition amount of TiC nanoparticles, the composite solders exhibited an improvement in their wettability. A negligible change in their melting point and a widened melting range were found in composite solders containing TiC reinforcement. Also, the CTE of composite solder alloys was effectively decreased when compared with the plain SAC solder alloy. In addition, a growth of interfacial IMCs in composite solder joints was notably suppressed under isothermal ageing condition, while their corresponding mechanical properties of composite solder joints significantly outperformed those of non-reinforced solder joints throughout the ageing period
Morphologies of AGN host galaxies using HST/ACS in the CDFS-GOODS field
Using HST/ACS images in four bands F435W, F606W, F775W and F850LP, we
identify optical counterparts to the X-ray sources in the Chandra Deep Field
South in the GOODS South field. A detailed study has been made of these sources
to study their morphological types. We use methods like decomposition of galaxy
luminosity profiles, color maps and visual inspection of 192 galaxies which are
identified as possible optical counterparts of Chandra X-ray sources in the
CDFS-GOODS field. We find that most moderate luminosity AGN hosts are bulge
dominated in the redshift range (z \approx 0.4-1.3), but not
merging/interacting galaxies. This implies probable fueling of the moderate
luminosity AGN by mechanisms other than those merger driven.Comment: pdflatex, accepted in ApSS. revisions in tex
A new ghost cell/level set method for moving boundary problems:application to tumor growth
In this paper, we present a ghost cell/level set method for the evolution of interfaces whose normal velocity depend upon the solutions of linear and nonlinear quasi-steady reaction-diffusion equations with curvature-dependent boundary conditions. Our technique includes a ghost cell method that accurately discretizes normal derivative jump boundary conditions without smearing jumps in the tangential derivative; a new iterative method for solving linear and nonlinear quasi-steady reaction-diffusion equations; an adaptive discretization to compute the curvature and normal vectors; and a new discrete approximation to the Heaviside function. We present numerical examples that demonstrate better than 1.5-order convergence for problems where traditional ghost cell methods either fail to converge or attain at best sub-linear accuracy. We apply our techniques to a model of tumor growth in complex, heterogeneous tissues that consists of a nonlinear nutrient equation and a pressure equation with geometry-dependent jump boundary conditions. We simulate the growth of glioblastoma (an aggressive brain tumor) into a large, 1 cm square of brain tissue that includes heterogeneous nutrient delivery and varied biomechanical characteristics (white matter, gray matter, cerebrospinal fluid, and bone), and we observe growth morphologies that are highly dependent upon the variations of the tissue characteristics—an effect observed in real tumor growth
Effects of macroscopic polarization in III-V nitride multi-quantum-wells
Huge built-in electric fields have been predicted to exist in wurtzite III-V
nitrides thin films and multilayers. Such fields originate from heterointerface
discontinuities of the macroscopic bulk polarization of the nitrides. Here we
discuss the background theory, the role of spontaneous polarization in this
context, and the practical implications of built-in polarization fields in
nitride nanostructures. To support our arguments, we present detailed
self-consistent tight-binding simulations of typical nitride QW structures in
which polarization effects are dominant.Comment: 11 pages, 9 figures, uses revtex/epsf. submitted to PR
Search for the Rare Decays J/Psi --> Ds- e+ nu_e, J/Psi --> D- e+ nu_e, and J/Psi --> D0bar e+ e-
We report on a search for the decays J/Psi --> Ds- e+ nu_e + c.c., J/Psi -->
D- e+ nu_e + c.c., and J/Psi --> D0bar e+ e- + c.c. in a sample of 5.8 * 10^7
J/Psi events collected with the BESII detector at the BEPC. No excess of signal
above background is observed, and 90% confidence level upper limits on the
branching fractions are set: B(J/Psi --> Ds- e+ nu_e + c.c.)<4.8*10^-5, B(J/Psi
--> D- e+ nu_e + c.c.) D0bar e+ e- + c.c.)<1.1*10^-5Comment: 10 pages, 4 figure
Direct Measurements of the Branching Fractions for and and Determinations of the Form Factors and
The absolute branching fractions for the decays and
are determined using singly
tagged sample from the data collected around 3.773 GeV with the
BES-II detector at the BEPC. In the system recoiling against the singly tagged
meson, events for and events for decays are observed. Those yield
the absolute branching fractions to be and . The
vector form factors are determined to be
and . The ratio of the two form
factors is measured to be .Comment: 6 pages, 5 figure
Study of J/psi decays to Lambda Lambdabar and Sigma0 Sigma0bar
The branching ratios and Angular distributions for J/psi decays to Lambda
Lambdabar and Sigma0 Sigma0bar are measured using BESII 58 million J/psi.Comment: 11 pages, 5 figure
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