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21.
22.
23.
A comparison between various recommended reference standards of diffuse reflectance in the IR is presented. It is shown that at a wavelength of 10.6 μm sulfur is the most Lambertian of the tested samples, although its powdery consistence makes it less suitable for use as a standard. Flame sprayed aluminum, with or without gold coating, also approaches a Lambertian surface and is suitable for use as a standard for BRDF measurements at 10.6 μm. Results for the BRDF of sulfur, gold-coated sandpaper, a commercial diffuse gold surface (by Labsphere) and flame sprayed aluminum are presented. 相似文献
24.
Mary E. Gbur 《Monatshefte für Mathematik》1976,81(2):95-107
C. Hightower found two infinite sequences of gaps in the Markov spectrum, (
n
,
n
) and (
n
,
n
) with
n
and
n
both Markov elements, converging to
. This paper exhibits Markov elements
n
*
and
n
*
such that, for alln 1, (
n
*
,
n
) and (
n
n
*
) are gaps in the Markov spectrum. Other results include showing that, for alln 1,
n
is completely isolated, while the other endpoints of the gaps are limit points in the Markov spectrum. 相似文献
25.
Conventional design of radiation detectors uses sintered ceramic insulating modules. The major drawback of these ceramic components
is their inherent brittleness. Ion chambers, in which these ceramic spacers are replaced by metallic components with plasma
spray coated alumina, have been developed in our Research Centre. These components act as thin spacers that have good mechanical
strength as well as high electrical insulation and replace alumina insulators with the same dimensions. As a result, the design
of the beam loss monitor ion chamber for CAT could be simplified by coating the outer surface of the HT electrode with alumina.
One of the chambers developed for isotope calibrator for brachytherapy gamma sources has its outer aluminium electrode (60
mm dia × 220 mm long) coated with 250 μ thick alumina (97%) + titania (3%).
In view of potential applications in neutron-sensitive ion chambers used in reactor control instrumentation, studies were
carried out on alumina 100 μ to 500 μ thick coatings on copper, aluminium and SS components. The electrical insulation varied
from 108 ohms to 1012 ohms for coating thicknesses above 200 μ. The porosity in the coating resulted in some fall in electrical insulation due
to moisture absorption. An improvement could be achieved by providing the ceramic surface with moisture-repellent silicone
oil coating. Irradiation at Apsara reactor core location showed that the coating on aluminium was found to be unaffected after
exposure to 1017 nvt fluence. 相似文献
26.
Algebras and Representation Theory - For the Kashiwara crystal of a highest weight representation of an affine Lie algebra of type A and rank e, with highest weight Λ, there is a labeling by... 相似文献
27.
Single crystals of pure, Ca2+ and Sr2+ doped NH4Sb3F10 are grown by slow evaporation technique. The effect of dopants on the growth and physicochemical properties also have been investigated and reported for the first time. The grown crystals are characterized with the aid of single crystal X-ray diffractometry to confirm the crystal structure. EDAX studies are done to confirm the presence of dopants in the crystal lattice. The vibrational frequencies of various group ligands in the crystals have been derived from the Fourier transform infrared (FT-IR) spectrum. From the optical absorption spectrum the band gap energy was calculated and it was found to be 5.76, 6.29 and 6.35 eV for pure, Ca2+ and Sr2+ doped NH4Sb3F10 crystals respectively. Thermal stability of the sample has been analysed using TG-DTA analysis. The activation energy of pure, Ca2+ and Sr2+ doped NH4Sb3F10 crystals were calculated from the dc conductivity measurements and it is found to be 0.2728, 0.2816 and 0.3622 eV Experimental results shows improved physicochemical properties when the dopant is added to the pure material. 相似文献
28.
Susan A. Kirch Mary Ellen Bargerhuff Heidi Turner Michele Wheatly 《School science and mathematics》2005,105(4):175-196
Inclusion is the meaningful participation of students with disabilities in general education classrooms. The CLASS project (Creating Laboratory Access for Science Students) is a unique initiative offering training and resources to help educators provide students with a variety of physical, sensory and learning disabilities equal access in the science laboratory or field. To determine whether participants believed a 2‐week residential workshop sponsored by CLASS raised disability awareness and provided teacher training in inclusive science teaching practice, a multipoint Likert scale survey and questionnaire was completed by all participants (N= 20) in four workshops. Participants reported large gains in their preparedness to teach science to students with disabilities. Participants also reported gains in their familiarity with instructional strategies, curricula, and resources and their ability to design, select, and modify activities for students with disabilities. Finally, shifts in attitudes about teaching science to students with disabilities were noted. 相似文献
29.
Differentiation of teaching and learning mathematics: an action research study in tertiary education
Panagiota Konstantinou-Katzi Eleni Tsolaki Maria Meletiou-Mavrotheris Mary Koutselini 《International Journal of Mathematical Education in Science & Technology》2013,44(3):332-349
Diversity and differentiation within our classrooms, at all levels of education, is nowadays a fact. It has been one of the biggest challenges for educators to respond to the needs of all students in such a mixed-ability classroom. Teachers’ inability to deal with students with different levels of readiness in a different way leads to school failure and all the negative outcomes that come with it. Differentiation of teaching and learning helps addressing this problem by respecting the different levels that exist in the classroom, and by responding to the needs of each learner. This article presents an action research study where a team of mathematics instructors and an expert in curriculum development developed and implemented a differentiated instruction learning environment in a first-year engineering calculus class at a university in Cyprus. This study provides evidence that differentiated instruction has a positive effect on student engagement and motivation and improves students’ understanding of difficult calculus concepts. 相似文献
30.
Cai QJ Chan-Park MB Lu ZS Li CM Ong BS 《Langmuir : the ACS journal of surfaces and colloids》2008,24(20):11889-11894
A series of alkanethiol monolayers (CH 3(CH 2) n-1 SH, n = 4, 6, 8, 10, 12, 14, 16) were used to modify gold source-drain electrode surfaces for bottom-contact poly(3,3'-didodecylquaterthiophene) (PQT-12) thin-film transistors (TFTs). The device mobilities of TFTs were significantly increased from approximately 0.015 cm (2) V (-1) s (-1) for bare electrode TFTs to a maximum of approximately 0.1 cm (2) V (-1) s (-1) for the n = 8 monolayer devices. The mobilities of devices with alkanethiol-modified Au electrodes varied parabolically with alkyl length with values of 0.06, 0.1, and 0.04 cm (2) V (-1) s (-1) at n = 4, 8, and 16, respectively. Atomic force microscopy investigations reveal that alkanethiol electrode surface modifications promote polycrystalline PQT-12 morphologies at electrode/PQT-12 contacts, which probably increase the density of states of the PQT-12 semiconductor at the interfaces. The contact resistance of TFTs is strongly modulated by the surface modification and strongly varies with the alkanethiol chain length. The surface modifications of electrodes appear to significantly improve the charge injection, with consequent substantial improvement in device performance. 相似文献