共查询到20条相似文献,搜索用时 31 毫秒
1.
Polad M. Shikhaliev Sabee Molloi 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2003,510(3):401-405
A novel scanning slit X-ray imaging system based on an “edge-on” microchannel plate detector was developed and tested. Images were acquired at 50 kV(p) X-ray tube voltage with a limiting spatial resolution of 7 lp/mm. The pixel noise was measured to be 0.3 count/pixel/s for a 50×70 μm2 pixel size. This photon counting detector can be considered to be virtually noise free. 相似文献
2.
This article presents an application of the “Six Sigma” DMAIC model to G.E.P. Box's famous “paper helicopter” experiment. The define, measure, and analyze phases are presented here, and the improve and control phases are presented in a follow-up article. The intent of this article is to present the reader with a case study for structuring a “Six Sigma” Black Belt project. 相似文献
3.
Maurice Touratier 《International Journal of Engineering Science》1983,21(12):1411-1436
An analysis of the dispersion of elastic waves is presented for two types of long ultrasonics wave-guides that we qualify of “bimorph”: (i) a “three-layer” guide made of two different materials and (ii) a “clad core” guide built up of a rectangular core surrounded by a cladding, the materials of the rod and cladding having different properties. An analytical model is proposed to describe the extensional, flexural and torsional motions in “bimorph” wave guides having two geometrical and material symmetry axes. The asymptotic behaviour of the model allows one to select the material properties which lead to modes guided essentially either in the central layer or in the core of the bimorph guide. Moreover, the dispersive properties of a “bimorph” can be controlled through the choice of geometrical and material parameters. 相似文献
4.
Various “living” polymers were grafted onto C60 The number of arms of the so obtained “star” molecules can be controlled by stoechiometry and/or by varying the reactivity of the carbanion on the “living” chain against a double bond on the C60. Even the oxanion of “living” polyethylenoxide is able to add onto the reactive double bonds on C60. In some conditions, the carbanions present on these alkaline salts of grafted fullerenes becomes able to initiate anionic polymerization of vinyl monomers. Using “living” poly(phenylvinylsulfoxide) as a precursor polymer for PA, polyacetylene chains could be attached to the fullerene. 相似文献
5.
Low-frequency internal friction and elastic modulus were studied for manganese-rich Mn–Cu alloys in the temperature range of martensitic transformation (20–300 °C). It is shown that the some special features of the transformation peak and its temperature are caused by the degree of the spinodal decomposition. The phenomenological model connecting an-elastic effects with the stages of evolution of the structure during martensitic transformation in manganese-rich Mn–Cu alloys (tweed structure–“parquet” structure–classical twinning martensite) is presented. 相似文献
6.
This article presents an application of the “Six Sigma” DMAIC model to G.E.P. Box's famous “paper helicopter” experiment. The Improve and Control Phases are presented here. The Define, Measure, and Analyze Phases were presented in an earlier paper. The intent of this article is to present the reader with a case study for structuring a “Six Sigma” project. 相似文献
7.
A. P. Martin A. N. Brunton G. W. Fraser A. F. Abbey 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2001,460(2-3):316-325
Following on from the proof-of principle measurements of Martin et al. (X-ray Spectrom. 28 (1999) 64) we further describe the development of an imaging X-ray fluorescence (IXRF) spectrometer with no moving parts. Our laboratory system is based on a microchannel plate (MCP) “lens”, a CCD X-ray detector with good sub-keV quantum efficiency and a conventional electron bombardment X-ray source. We have used this equipment to form images of a standard XRF target, demonstrating that “elemental maps” (images of the target in the characteristic X-rays of one particular element) may be formed with sub-millimetre resolution. In addition to fluorescent X-rays, we detected X-rays which had been Bragg reflected from the polycrystalline aluminium substrate of the target. It is possible that the resulting “Bragg images” may be exploited to measure spatially varying strain, manifested as lattice distortion, introduced, for example, by thin films deposited on the surface of a sample. 相似文献
8.
Different bioadhesive and matrix-forming polymers were evaluated using “in-vitro” tests to identify a potentially convenient “in-vivo” formulation for the sustained delivery of hydrocortisone hemisuccinate to the oral cavity. The selected composition allows an erosion-diffusion mechanism coherent with the low hydrosolubility of the drug and with potential advantages for both the patient and the manufacturer. 相似文献
9.
B. Perea Solano M.C. Abreu V. Avati T. Boccali V. Boccone M. Bozzo R. Capra L. Casagrande W. Chen K. Eggert E. Heijne S. Klauke Z. Li T. Mki L. Mirabito A. Morelli T.O. Niinikoski F. Oljemark V.G. Palmieri P. Rato Mendes S. Rodrigues P. Siegrist L. Silvestris P. Sousa S. Tapprogge B. Trocm 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2005,550(3):567-580
We report measurements in a high-energy beam of the sensitivity of the edge region in “edgeless” planar silicon pad diode detectors. The edgeless side of these rectangular diodes is formed by a cut and break through the contact implants. A large surface current on such an edge prevents the normal reverse biasing of this device above the full depletion voltage, but we have shown that the current can be sufficiently reduced by the use of a suitable cutting method, followed by edge treatment, and by operating the detector at a low temperature. A pair of these edgeless silicon diode pad sensors was exposed to the X5 high-energy pion beam at CERN, to determine the edge sensitivity. The signal of the detector pair triggered a reference telescope made of silicon microstrip detector modules. The gap width between the edgeless sensors, determined using the tracks measured by the reference telescope, was then compared with the results of precision metrology. It was concluded that the depth of the dead layer at the diced edge is compatible with zero within the statistical precision of ±8 μm and systematic error of ±6 μm. 相似文献
10.
“Low-Tech” Innovations 总被引:1,自引:0,他引:1
Hartmut Hirsch‐Kreinsen 《Industry and innovation》2008,15(1):19-43
This paper is about an industrial sector which, according to the usual socio-scientific indicators, is referred to as “low-tech”, respectively as non-research intensive and which mostly comprises “traditional” industries. The interest in this sector is motivated by the contradictory situation that, on the one hand, the debate about the perspectives of modern societies focuses on the rapidly growing importance of technological innovations, knowledge and research-intensive economic sectors while, on the other hand, traditional industries make up a considerable fraction of employment and production, especially also in developed economies. On the basis of the results of extensive empirical research, this contribution tries to find answers to the basic question, whether one can speak of an innovation mode typical of the low-tech sector. The institutional based innovation systems approach forms the categorical basis of the analysis. In order to elucidate the specific features of low-tech innovations, they are, in conclusion, compared to the general characteristics of high-tech-based innovation processes. 相似文献
11.
Three automotive corporations have developed and sanctioned the recently revised reference manual entitled Measurement Systems Analysis. This “standard” contains a procedure, called the “analytic method,” whose purpose is to estimate the gage bias and gage repeatability of an attribute gage. An improved estimation procedure for this standard is presented. The improved estimation procedure yields more accurate estimates than those obtained using the procedures currently presented in the standard. In addition, the improved procedure allows more flexibility in data collection than the current test protocol. A simulation study that evaluates the estimation procedure of the current standard and compares it with the improved estimation procedure is presented. Errors that are contained in the present standard are also noted. 相似文献
12.
The “Six Sigma” management DMADV model is used in this paper to design a new dormitory concept at the University of Miami. It is intended to provide a roadmap for conducting a Design for Six Sigma (DFSS) project. 相似文献
13.
A common procedure in budget allocation is to let the different entities of an organization determine their optimal budgets. Once the individual requests are received, they are then cut by a common factor, as necessary, so that a global constraint is satisfied. We refer to this procedure as the “cut across the board” rule. In general, this method will not result in a globally optimal solution. In this paper we identify conditions that assure the global optimality of die “cut (or expand) across the board” rule. We specifically focus on a constrained multi-item inventory model and generalize results of Rosenblatt [10] and Plossl and Wight [8]. In addition, we briefly discuss applicability of the results to other areas. 相似文献
14.
In this work, the microstructures and tensile properties of a commercial magnesium alloy “AZ61” processed by a combination of hot extrusion and thermomechanical processing (TMP) were investigated. The TMP was consisting of two or three hot rolling steps with large reductions per pass, thus allowing significant grain refinement. The microstructural evolution has been studied by means of optical and scanning electron microscopes, as well as X-ray diffraction analysis. The as-cast material is extruded in the form of a cylinder with initial diameter of 250 mm to a final diameter of 110 mm (80% reduction in cross-sectional area). Then hot rolling regimes were performed at 300 °C with different percentage of strain per pass. Tensile and hardness tests were performed in the samples (as-cast, extruded, and rolled) at room temperature in order to evaluate the mechanical properties of the material. The results of experiments demonstrated that fine grain size might be achieved in magnesium alloy AZ61 by using a two-step processing route involving an initial extrusion step followed by thermomechanical processing with large reduction in thickness per pass. This two-step process, designed to achieve average grain sizes of 10–20 μm. 相似文献
15.
John G. Cramer 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1996,370(2-3):516-520
We present a new “no-background” procedure, based on the maximum likelihood method, for fitting the space-time size parameters of the particle production region in ultra-relativistic heavy ion collisions. This procedure uses an approximation to avoid the necessity of constructing a mixed-event background before fitting the data. 相似文献
16.
17.
V.B. Sokolinsky 《Engineering Fracture Mechanics》1981,14(4):753-758
The enhanced strength observed for bodies under dynamic loading has been attributed to fracturing duration, i.e. the time interval between the commencement of fracture at the most heavily loaded point of the body and the instant of completion of fracture which is recorded by a sensor. The “dynamic” strength of brittle bodies is shown to be related to the crack formation process. 相似文献
18.
SiO2 surface film is insufficient to protect SiC from the oxidation at widely varying partial pressures of oxygen, in particular in the presence of water vapor (e.g. in gas turbines) and also in other environments, e.g. during brazing for hard “tipping” of turbine blades. This work demonstrates that sol–gel alumina, coated on 0.5 mm coarse SiC grit, may form an acceptable, up to 10 μm thick “environmental barrier coating” EBC for some of these applications. The sol–gel has advantages over other methods (such as CVD) is the simplicity and low cost. We have used NH4OH pre-treatment to hydroxylate surface of SiC prior to applying alumina coating. Such modified SiC/SiO2 surface helped to deposit the positively charged alumina sol, and thus allowed to build thick coatings on the SiC grit. There is some indication that these coatings partially convert to mullite through reaction at the interface with the native silica on SiC. Oxidation resistance tests at 1200 °C were performed to show effectiveness of such coated SiC grit. 相似文献
19.
The anomalous growth behavior of short fatigue cracks in a Ni-based superalloy is examined. Experimental and analytical work is presented which clearly demonstrates the break-down of linear elastic fracture mechanics (LEFM) in the “so-called” short crack regime. Short crack data only appear anomalous when correlated in terms of the stress intensity factor. When short and long crack data are analyzed in terms of a more valid driving force (e.g. strain energy density criteria), no anomalous short crack behavior is observed. 相似文献
20.
This work empirically evaluates the “entrapment” procedure used by Barnes and Brennan's branch-and-bound algorithm to minimize total cost of tardy jobs to be processed on identical machines. Using 25 problems taken from various known sources, it is shown that entrapment does not necessarily decrease computational time required to optimally solve such a problem. 相似文献