The diffuse reflection (DR) spectrum of a sample consisting of a mixture of rare earth oxides and talc was measured at 2 cm-1 resolution, using five different accessories installed on five different Fourier transform near-infrared (FT-NIR) spectrometers from four manufacturers. Peak positions for 37 peaks were determined using two peak-picking algorithms: center-of-mass and polynomial fitting. The wavenumber of the band center reported by either of these techniques was sensitive to the slope of the baseline, and so the baseline of the spectra was corrected using either a polynomial fit or conversion to the second derivative. Significantly different results were obtained with one combination of spectrometer and accessory than the others. Apparently, the beam path through the interferometer and DR accessory was different for this accessory than for any of the other measurements, causing a severe degradation of the resolution. Spectra measured on this instrument were removed as outliers. For measurements made on FT-NIR spectrometers, it is shown that it is important to check the resolution at which the spectrum has been measured using lines in the vibration-rotation spectrum of atmospheric water vapor and to specify the peak-picking and baseline-correction algorithms that are used to process the measured spectra. The variance between the results given by the four different methods of peak-picking and baseline correction was substantially larger than the variance between the remaining five measurements. Certain bands were found to be more suitable than others for use as wavelength standards. A band at 5943.13 cm-1 (1682.62 nm) was found to be the most stable band between the four methods and the six measurements. A band at 5177.04 cm-1 (1931.61 nm) has the highest precision between different measurements when polynomial baseline correction and polynomial peak-picking algorithms are used. 相似文献
Designing autonomic fault responses is difficult, particularly in large-scale systems, as there is no single ‘perfect’ fault
mitigation response to a given failure. The design of appropriate mitigation actions depend upon the goals and state of the
application and environment. Strict time deadlines in real-time systems further exacerbate this problem. Any autonomic behavior
in such systems must not only be functionally correct but should also conform to properties of liveness, safety and bounded
time responsiveness. This paper details a real-time fault-tolerant framework, which uses a reflex and healing architecture
to provide fault mitigation capabilities for large-scale real-time systems. At the heart of this architecture is a real-time
reflex engine, which has a state-based failure management logic that can respond to both event- and time-based triggers. We
also present a semantic domain for verifying properties of systems, which use this framework of real-time reflex engines.
Lastly, a case study, which examines the details of such an approach, is presented. 相似文献
The trienoic and tetraenoic polyenes, (3Z,6Z,9Z)-3,6,9-nonadecatriene, (3Z,6Z,9Z)-3,6,9-henicosatriene, and (3Z,6Z,9Z)-1,3,6,9-henicosatetraene were found in the abdominal cuticle and pheromone gland of the winter moth Operophtera brumata L. (Lepidoptera: Geometridae), in addition to the previously identified single component sex pheromone (3Z,6Z,9Z)-1,3,6,9-nonadecatetraene. The pheromone biosynthesis activating neuropeptide (PBAN) is involved in the regulation of polyene transport from abdominal cuticle to the pheromone gland. In vivo deuterium labeling experiments showed that (11Z,14Z,17Z)-11,14,17-icosatrienoic acid, the malonate elongation product of linolenic acid, (9Z,12Z,15Z)-9,12,15-octadecatrienoic acid, is used to produce (3Z,6Z,9Z)-3,6,9-nonadecatriene and (3Z,6Z,9Z)-1,3,6,9-nonadecatetraene. 相似文献
Nuclear energy is increasingly perceived as an attractive mature energy generation technology that can deliver an answer to the worldwide increasing energy demand while respecting environmental concerns as well as contributing to a reduced dependence on fossil fuel. Advancing nuclear energy deployment demands an assessment of nuclear energy with respect to all sustainability dimensions.In this paper, the nuclear energy, whose sustainability will be assessed, is governed by the dynamics of three subsystems: environmental, economic, and sociopolitical. The overall sustainability is then a non-linear function of the individual sustainabilities. Each subsystem is evaluated by means of many components (pressure, status, and response). The combination of each group of indicators by means of fuzzy logic provides a measurement of sustainability for each subsystem. 相似文献
A high-resolution 3D scanning technique called X-ray microtomography was applied to measure internal damage and crack growth in small mortar cylinders loaded in compression. Synchrotron-based microtomography allows us to resolve internal features that are only a few microns in size. Multiple tomographic scans were made of the same specimen at different levels of deformation using a custom-built loading frame. 3D image analysis was used to measure internal crack growth during each deformation increment. Measured load-deformation curves were used to calculate the nonrecoverable work of the external load on the specimen. Nonrecoverable work of load was related to measured incremental change in crack surface area to estimate work-of-fracture in three dimensions. Initial results indicate a nearly constant work-of-fracture for the early stages of crack growth. These results show that basic fracture mechanics principles may be applied to concrete in compression; however, we must think in terms of 3D multiple crack systems rather than traditional 2D single crack systems. 相似文献
Fe-ZSM-5 zeolites comprise of three types (I, II and III) of iron (Fe3+) sites in both as synthesized (AS) and heat-treated states. Previous evidence could be confirmed by the assignment of ESR lines, registered in the X-band, stating: (i) type I framework Fe3+ sites (in Th oxygen coordination), where charge compensation occurs mainly by Na+ ions and the crystal field (cf) approximates cubic symmetry, produce resonances at near to g = 2.00; (ii) type II and probably type III binuclear Fe...Fe dioxo- and oxo-bridges manifest themselves in producing slightly distorted surroundings of axial symmetry, and the relevant powder-averaged subspectrum is superimposed on the previous one in the g 2.45–1.98 interval. As the temperature of the heat-treatment (HT) is raised, type II and III sites will be annihilated with preference, under concomitant production of amorphous Fe2O3 possessing molecular dispersity. (iii) The weak ESR signal (2–4%) at g 4.27 is attributed to Th coordinated framework sites in the surface layers (≈ 1 u.c. thick) under the influence of solid surface tension, giving rise to fully rhombic cf symmetry.
The size of the ejected Fe2O3 particles, as estimated from Mössbauer spectra (no hyperfine structure at 77 K) is less than 2.9 nm. The extremely large electron affinity of Fe3+ ions manifests itself in decreased ionicity (and unexpectedly dominant cubic symmetry), activity in biomimetic oxidations, autoreduction and spontaneous reoxidation etc.
In the liquid phase oxidation by hydrogen peroxide of n-hexane and cyclohexane the heat-treated Ti-ZSM-5 samples exhibited both activity- and selectivity dependence on HT. On the basis of experiences drawn from the heat-treatments proposal is made for the structures of the defect site (producing the 960 cm−1 IR signal) and the active centre of selective oxidation. The proposal seems to be in accord with the experimental observations (isotopic exchange, MAS-NMR behaviour etc.) published so far. 相似文献
For the general calculation of the transformation of steels the transformation diagram for isothermal transformation must be known. It is described, how from dilatometric measurements with continuous cooling the transformation at a constant temperature can be calculated. To do this, the simplex method must be used as iteration process to achieve sufficient precision. Even when measuring data are scattered around an ideal value by ±5% the transformation diagram for isothermal transformation can be calculated with considerable accuracy. 相似文献
Alternating current potential drop (ACPD) is an established technique for non-destructive testing and materials characterisation. Finite element (FE) simulation is a very useful tool for the optimisation of probes and the prediction of test results, but three-dimensional models of ACPD problems are computationally intensive. This paper presents a new, simple model in which frequency-related effects are taken into account by appropriately modifying the geometry of the modelled structure: a DC analysis can then be performed on a smaller domain, thus reducing the computational power required. The results of experimental tests for the validation of the model are also presented and discussed. 相似文献