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991.
网络安全是多领域的综合业务,近10年来在规模和范围方面都获得了极大的发展。对网络及内容潜在的威胁来自各类不同的领域.因此增加了解决这一问题的难度。 相似文献
992.
Milad Ja Lilian Tao Shui Himadri Rajput Greg Naterer Sophia He Yulin Hu 《加拿大化工杂志》2024,102(3):1039-1050
Hydrothermal carbonization (HTC) of sawdust for producing hydrochar was optimized using response surface methodology (RSM). After optimization, the combustion behaviour and other relevant fuel properties of hydrochar that was obtained at the optimized conditions were studied. Additionally, the aqueous phase obtained at the optimized conditions was recycled as the reaction medium for producing hydrochar and the influence of the aqueous phase recycling on the hydrochar yield and properties was evaluated. The results indicated that the highest hydrochar yield of 84.23 wt.% under the predicted optimum conditions of temperature of 162.23°C, 2.51 h, feedstock loading of 10.71 wt.%, and catalyst loading of 7.99 wt.%. Furthermore, it was found that the use of recycled aqueous phase as the reaction medium led to an increase in the hydrochar yield, higher heating value (HHV), and energy yield, and difference in combustion behaviour was minor. Overall, this study filled the gap in HTC literature regarding the effect of catalyst on hydrochar production and provided a practical solution to treat the aqueous phase. 相似文献
993.
Rollinson CM Wade SA Kouskousis BP Kitcher DJ Baxter GW Collins SF 《Journal of the Optical Society of America. A, Optics, image science, and vision》2012,29(7):1259-1268
The growth of reflectance peaks from optical fiber Bragg gratings has been studied to determine the relative importance of grating features when writing with the phase-mask technique. Measurements of spectra for two different fiber types using two distinct phase masks allowed the contribution from grating features of half the phase-mask periodicity and of the phase-mask periodicity at the Bragg wavelength to be determined. The dominance of the latter periodicity was ascribed to either the small fiber core diameter that limited the extent of the Talbot diffraction pattern, or the enhanced ±2 diffraction orders of a custom-made phase mask used. 相似文献
994.
Phase singularities, correlation singularities, and conditions for complete destructive interference
Rosenbury C Gu Y Gbur G 《Journal of the Optical Society of America. A, Optics, image science, and vision》2012,29(4):410-416
A previously derived condition for the complete destructive interference of partially coherent light emerging from a trio of pinholes in an opaque screen is generalized to the case when the coherence properties of the field are asymmetric. It is shown by example that the interference condition is necessary, but not sufficient, and that the existence of complete destructive interference also depends on the intensity of light emerging from the pinholes and the system geometry; more general conditions for such interference are derived. The phase of the wave field exhibits both phase singularities and correlation singularities, and a number of nonintuitive situations in which complete destructive interference occurs are described and explained. 相似文献
995.
996.
Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the gastrointestinal system. Omega-3 (ω3) fatty acids are polyunsaturated fatty acids (PUFAs) that are largely obtained from diet and have been speculated to decrease the inflammatory response that is involved in IBD; however, the causality of this association has not been established. A two-sample Mendelian randomization (MR) was used to assess genetic associations between 249 circulating metabolites measured in the UK Biobank as exposures and IBD as the outcome. The genome-wide association study summary level data for metabolite measurements and IBD were derived from large European ancestry cohorts. We observed ω3 fatty acids as a significant protective association with IBD, with multiple modes of MR evidence replicated in three IBD summary genetic datasets. The instrumental variables that were involved in the causal association of ω3 fatty acids with IBD highlighted an intronic SNP, rs174564, in FADS2, a protein engaged in the first step of alpha-linolenic acid desaturation leading to anti-inflammatory EPA and thence DHA production. A low ratio of ω3 to ω6 fatty acids was observed to be a causal risk factor, particularly for Crohn’s disease. ω3 fatty acid supplementation may provide anti-inflammatory responses that are required to attenuate inflammation that is involved in IBD. 相似文献
997.
Greg White 《International Journal of Pavement Engineering》2017,18(10):887-901
Interface shear resistance is a measure of the bonding between two layers under shear loading. Adequate interface shear resistance and long-term bonding of the surface to the underlying pavement are critical to the performance of pavement structures. Interface shear strength is a function of adhesion, friction and aggregate embedment or interlock and is commonly modelled as a Mohr–Coulomb type envelope. Measurement of interface shear resistance can be performed in the field on full-scale pavements, in the laboratory on cores recovered from the surface or in the laboratory using samples prepared in the laboratory. However, laboratory testing of cores recovered from the field is likely to be more reliable and repeatable than field testing. There is a large range of test methods and procedures for the measurement of interface bond. These test methods are generally grouped into three main loading mechanisms; axial tension, torsional shear and direct shear. Direct shear tests offer a more comprehensive assessment of the full interface strength. The interface’s resistance to shear can be characterised by its strength, modulus/stiffness or work/energy. The results are affected by the test protocol, tack coat type and application rate, test temperature, applied normal stress and rate of loading, interface condition and post-construction trafficking. Of these, the test temperature is the most influential factor. A number of studies have reported contradictory and conflicting conclusions with regard to the importance of various factors and conditions on the different measures of interface shear resistance. Such inconsistent findings likely stem from the complicated interaction between the various interface conditions and testing protocols. The fundamental factors affecting monotonic interface strength are now reasonably well understood. The focus of future research is expected to be on shear fatigue performance of interfaces. 相似文献
998.
999.
Abhishek Parikh Janna Martinek Greg Mungas Nick Kramer Robert Braun Guangdong Zhu 《国际能源研究杂志》2019,43(9):4051-4061
A linear Fresnel collector design with an operation temperature of 300°C or above typically requires a solar flux concentration ratio of at least 20 on the surfaces of the receiver assembly. For the commercial linear Fresnel collector design in this work, the receiver assembly includes a secondary reflector and an evacuated receiver tube. The high‐concentration solar flux may impose additional operating‐temperature requirements on the secondary reflector and receiver tube. Thus, a careful heat‐transfer analysis is necessary to understand the operating temperature of the receiver assembly component surfaces under design and off‐design conditions to guide appropriate material selections. In this work, a numerical heat‐transfer analysis is performed to calculate the temperature distribution of the surfaces of the secondary reflector and receiver glass envelope for a commercial collector design. Operating conditions examined in the heat‐transfer analysis include various wind speeds and solar concentration ratios. The results indicate a surface temperature higher than 100°C on the secondary reflector surface, which suggests that a more advanced secondary reflector material is needed. The established heat‐transfer model can be used for optimization of the other types of linear Fresnel collectors. 相似文献
1000.
Worriers avoid upsetting thoughts yet also demonstrate vigilance for aversive emotional information. Potentially, these processes coexist but are separated in time. Individuals scoring high on a measure of chronic uncontrollable worry were compared to low scorers during valence categorization of emotional stimuli with interleaved Stroop color word trials to monitor extended effects of emotional processing. High worriers were especially fast and accurate in judging the valence of emotional words compared to low worriers. Worriers also had smaller pupil diameters following personally relevant negative emotional stimuli compared to low worriers. Correlations with self-report scales indicated associations between the worrier pupil response profile and symptoms of chronic worry and depression. The combined behavioral and physiological data support theories of emotional vigilance followed by avoidance in worriers. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献