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1.
The study of hydration of expansive cement prepared from 64% portland cement clinker, 23% metakaolinite and 13% CaSO4.2H2O is described. It was found that in the course of a 10-day hydration period, all the gypsum entered the reaction with the formation of ettringite. In 7–10 days, after the termination of the expansion processes, typical stalk-like crystals were transformed into leaf-shaped or other formations. Ettringite was identified even after 4 months of hydration. Monosulphate (3CaO.Al2O3.CaSO4.12H2O) was found in none of the investigated high-expansion cement paste samples. 相似文献
2.
We have found experimentally that rf SQUID's working in a nonhysteretic mode with small critical currents give exactly at resonance and at very low rf bias a triangular pattern with a period equal to half of one elementary quantum of magnetic flux. We discuss a possible explanation of this peculiar result. 相似文献
3.
Lubomir Mraz Vladimir Cervenka Dan Komosny Milan Simek 《Wireless Personal Communications》2013,71(4):2783-2803
Although the ZigBee technology is massively deployed the performance question still remains unanswered. There is a lack of serious performance evaluations and thus this paper provides a comprehensive and unbiased study of the ZigBee PRO technology. An extensive real measurement was conducted to accomplish this task. We found out a big performance gap among ZigBee implementations even though they are compliant with the ZigBee standard. The presented results and analysis could be beneficial for many wireless sensor network developers. 相似文献
4.
Oost E Koning G Sonka M Oemrawsingh PV Reiber JH Lelieveldt BP 《IEEE transactions on medical imaging》2006,25(9):1158-1171
This paper describes a new approach to the automated segmentation of X-ray left ventricular (LV) angiograms, based on active appearance models (AAMs) and dynamic programming. A coupling of shape and texture information between the end-diastolic (ED) and end-systolic (ES) frame was achieved by constructing a multiview AAM. Over-constraining of the model was compensated for by employing dynamic programming, integrating both intensity and motion features in the cost function. Two applications are compared: a semi-automatic method with manual model initialization, and a fully automatic algorithm. The first proved to be highly robust and accurate, demonstrating high clinical relevance. Based on experiments involving 70 patient data sets, the algorithm's success rate was 100% for ED and 99% for ES, with average unsigned border positioning errors of 0.68 mm for ED and 1.45 mm for ES. Calculated volumes were accurate and unbiased. The fully automatic algorithm, with intrinsically less user interaction was less robust, but showed a high potential, mostly due to a controlled gradient descent in updating the model parameters. The success rate of the fully automatic method was 91% for ED and 83% for ES, with average unsigned border positioning errors of 0.79 mm for ED and 1.55 mm for ES. 相似文献
5.
Three-dimensional segmentation of fluid-associated abnormalities in retinal OCT: probability constrained graph-search-graph-cut 总被引:1,自引:0,他引:1
Chen X Niemeijer M Zhang L Lee K Abramoff MD Sonka M 《IEEE transactions on medical imaging》2012,31(8):1521-1531
An automated method is reported for segmenting 3-D fluid-associated abnormalities in the retina, so-called symptomatic exudate-associated derangements (SEAD), from 3-D OCT retinal images of subjects suffering from exudative age-related macular degeneration. In the first stage of a two-stage approach, retinal layers are segmented, candidate SEAD regions identified, and the retinal OCT image is flattened using a candidate-SEAD aware approach. In the second stage, a probability constrained combined graph search-graph cut method refines the candidate SEADs by integrating the candidate volumes into the graph cut cost function as probability constraints. The proposed method was evaluated on 15 spectral domain OCT images from 15 subjects undergoing intravitreal anti-VEGF injection treatment. Leave-one-out evaluation resulted in a true positive volume fraction (TPVF), false positive volume fraction (FPVF) and relative volume difference ratio (RVDR) of 86.5%, 1.7%, and 12.8%, respectively. The new graph cut-graph search method significantly outperformed both the traditional graph cut and traditional graph search approaches (p < 0.01, p < 0.04) and has the potential to improve clinical management of patients with choroidal neovascularization due to exudative age-related macular degeneration. 相似文献
6.
Physical Mechanisms behind the Field‐Cycling Behavior of HfO2‐Based Ferroelectric Capacitors 下载免费PDF全文
Milan Pešić Franz Paul Gustav Fengler Luca Larcher Andrea Padovani Tony Schenk Everett D. Grimley Xiahan Sang James M. LeBeau Stefan Slesazeck Uwe Schroeder Thomas Mikolajick 《Advanced functional materials》2016,26(25):4601-4612
Novel hafnium oxide (HfO2)‐based ferroelectrics reveal full scalability and complementary metal oxide semiconductor integratability compared to perovskite‐based ferroelectrics that are currently used in nonvolatile ferroelectric random access memories (FeRAMs). Within the lifetime of the device, two main regimes of wake‐up and fatigue can be identified. Up to now, the mechanisms behind these two device stages have not been revealed. Thus, the main scope of this study is an identification of the root cause for the increase of the remnant polarization during the wake‐up phase and subsequent polarization degradation with further cycling. Combining the comprehensive ferroelectric switching current experiments, Preisach density analysis, and transmission electron microscopy (TEM) study with compact and Technology Computer Aided Design (TCAD) modeling, it has been found out that during the wake‐up of the device no new defects are generated but the existing defects redistribute within the device. Furthermore, vacancy diffusion has been identified as the main cause for the phase transformation and consequent increase of the remnant polarization. Utilizing trap density spectroscopy for examining defect evolution with cycling of the device together with modeling of the degradation results in an understanding of the main mechanisms behind the evolution of the ferroelectric response. 相似文献
7.
J. Karovičová Milan Drdák Gabriel Greif Eva Hybenová 《European Food Research and Technology》1999,210(1):53-56
The reasons for using lactic acid bacteria are to make food durable, to improve its taste and to maintain the nutritive,
physiological and hygienic value of the fermentation products. Sixteen strains of the genus Lactobacillus were tested on samples of white fresh cabbage and of a sterilized cabbage and carrot juice mixture. After 7 days of lactic
acid fermentation at 27 °C or 30 °C, reducing sugars, total acidity, pH value, lactic, citric and acetic acids, ammonia,
nitrates and nitrites were measured in the samples. On the basis of the criteria mentioned above three strains were acceptable.
These strains reduced the content of nitrates in the original samples.
Received: 14 December 1998 / Revised version: 18 March 1999 相似文献
8.
Panagiotis Dallas Jiri Tucek Dalibor Jancik Milan Kolar Ales Panacek Radek Zboril 《Advanced functional materials》2010,20(14):2347-2354
A recently developed multi‐functional phosphotriazine‐based polymer is used as a matrix for embedding γ‐Fe2O3 nanoparticles as well as a suitable chemical template for surface modification with silver nanoparticles. For the primary magnetic modification, maghemite nanoparticles are surface modified with oleic acid in order to render them organophilic and to prevent the aggregation of the nanoparticles. This aggregation could occur as the polymer synthesis, based on reaction of phosphonitrilic chlorine and 1,4‐phenylenediamine, takes place in toluene. The surface active amine units of the polymer structure enable the reduction of silver cations to silver nanoparticles, which are well attached and finely dispersed on its surface. The developed nanocomposite represents one of the few magnetically controllable antibacterial agents based on silver nanoparticles. Magnetic measurements reveal the completely suppressed interactions among maghemite nanoparticles because of their perfect surface coating with an organic surfactant and fine dispersion inside the polymer matrix. This magnetic nanocomposite exhibits a high antibacterial and antifungal activity as proven by tests with nine bacterial strains and four candida (yeast genus) species. For the majority of the tested species, the minimum‐inhibition concentrations are below 100 mg L?1, which is comparable to their equivalent minimum‐inhibition concentrations in colloidal silver systems. 相似文献
9.
Milan M. Jevti 《Microelectronics Reliability》2004,44(7):1123-1129
An approach to analyze the optocouplers with phototransistors by low frequency noise measurements is presented in this paper. The analysis is based on the measurements of LED and output noises of optocouplers. We have shown that the corner frequency in output noise can be caused by frequency dependence of dynamic current gain of phototransistor under conditions of open base circuit. A noise parameter as an indicator of optocoupler's phototransistor current gain degradation is proposed. The contributions of noise sources of LED and phototransistor to the frequency dependence of the output noise spectrum are also considered. 相似文献