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991.
In this paper I deal with an early phase of the history of research on black-body radiation. In this phase,
from 1880-1900, the American astrophysicist Samuel Pierpont Langley (1834-1906) invented and used
a key instrument, the bolometer, to measure for the first time radiation curves that displayed the
characteristic features of asymmetry and of a shifting of their maxima to shorter wavelengths with
increasing temperature. I emphasize the complex development of the construction of the bolometer and
the early experiments performed with it. I also discuss how these developments became important for
theoretical research on the black-body radiation formula. My aim is to show that the often-neglected
experimental part of the history of research on black-body radiation represents an important precondition
for the theoretical developments that followed. 相似文献
992.
The problem of how mathematics and physics are related at a foundational level is of interest. The approach taken here is
to work towards a coherent theory of physics and mathematics together by examining the theory experiment connection. The role
of an implied theory hierarchy and use of computers in comparing theory and experiment is described. The main idea of the
paper is to tighten the theory experiment connection by bringing physical theories, as mathematical structures over C, the complex numbers, closer to what is actually done in experimental measurements and computations. The method replaces
C by Cn which is the set of pairs, Rn,In, of n figure rational numbers in some basis. The properties of these numbers are based on those of numerical measurement outcomes
for continuous variables. A model of space and time based on Rn is discussed. The model is scale invariant with regions of constant step size interrupted by exponential jumps. A method
of taking the limit n→∞ to obtain locally flat continuum-based space and time is outlined. Also Rn based space is invariant under scale transformations. These correspond to expansion and contraction of space relative to
a flat background. The location of the origin, which is a space and time singularity, does not change under these transformations.
Some properties of quantum mechanics, based on Cn and on Rn space are briefly investigated. 相似文献
993.
We present the final results obtained by the MACRO experiment in the search for GUT magnetic monopoles and nuclearites. Several searches were performed with different subdetectors, i.e. scintillation counters, limited streamer tubes and nuclear track detectors. No magnetic monopole or nuclearite candidates were found. The MACRO upper limit to the local flux of GUT magnetic monopoles is at the level of 1.4×10−16 cm−2 s−1 sr−1. 相似文献
994.
995.
996.
《Electroanalysis》2005,17(17):1563-1570
The electrochemical reduction behavior of mefloquine HCl (MEF), the antimalarial drug, was studied in aqueous alcoholic media at a hanging mercury drop electrode. Cyclic voltammetric studies showed one well‐defined reduction peak and one ill‐defined reduction wave between pH 1.5 and 12.03. The reduction was found as irreversible or quasireversible depending on pH and exhibited diffusion controlled process. The mechanism of reduction process was discussed. A systematic study of the experimental parameters that affect the differential pulse and square wave response was carried out and the optimized experimental conditions were obtained. The calibration plots were derived for the determination of MEF in pharmaceutical dosage forms and biological samples. DPV and SWV techniques for the determination of MEF in Britton–Robinson buffer at pH 11.10, which allows quantitation over the 6×10?6 to 8×10?5 M range in the supporting electrolyte, were proposed. The linear response was obtained in samples in the ranges of 6×10?6 to 6×10?5 M for both techniques. These methods are fully validated. The standard addition method was used in the biological media. No electroactive interferences from the excipients and endogenous substances were found in tablets and biological fluids. 相似文献
997.
对民族服饰图案进行自动分割以提取图案纹样元素,是民族服饰图案素材库构建急需解决的难题。通过融合形态学连通域标记和CV模型(MCC-CV),提出了一种民族服饰图案自动分割方法,首先对民族服饰图案进行预处理,然后采用形态学连通域标记算法获得待分割目标的位置和大致轮廓信息,对CV模型进行初始化,最后通过CV模型对不同分割目标进行边缘追踪,以实现民族服饰图案纹样元素的自动分割。实验表明,融合形态学连通域和CV模型的民族服饰图案纹样元素自动分割方法在边界召回率(BR)为0.5时,分割准确率为60%,与其他自动分割算法相比,该算法更为有效,满足了民族服饰图案素材库建设对图案纹样元素分割的基本要求。 相似文献
998.
D S Narayan 《Pramana》1979,12(4):391-395
The production of prompt neutrinos in the beam dump experiment is explained in a cluster model, by postulating the emission
of strange clusters in hadron collisions, besides the usual non-strange clusters. The low mass strange clusters can decay
only by the weak interaction. The leptonic and semi-leptonic decay modes of these clusters give rise to prompt neutrinos.
A prediction of the model is that the ratios <v
e>/π
+ at PS energies would be the same as SPS energies. 相似文献
999.
T M Karade 《Pramana》1978,11(1):55-66
By constructing a composite mapping of Voigt and Lorentz transformations some new non relativistic transformations of conformal
type are obtained where the laws of Maxwell’s electromagnetic theory are found to be invariant. This new scheme is consistent
with some of the well established experimental facts. 相似文献
1000.