Binary sampling ghost imaging: add random noise to fight quantization caused image quality decline

When the sampling data of ghost imaging is recorded with less bits, i.e., experiencing quantization, decline of image quality is observed. The less bits used, the worse image one gets. Dithering, which adds suitable random noise to the raw data before quantization, is proved to be capable of compensating image quality decline effectively, even for the extreme binary sampling case. A brief explanation and parameter optimization of dithering are given.Comment: 8 pages, 7 figure

LH-moment estimation for statistical analysis on the wave crest distributions of a deepwater spar platform model test

The design of fixed and compliant offshore platforms requires the reliable estimation of extreme values with small probabilities of exceedance based on an appropriate probability distribution. The Weibull distribution is commonly utilised for the statistical analysis of wave crests, including near-field wave run-ups. The parameters are estimated empirically from experimental or onsite measurements. In this paper, the data set of wave crests from a Spar model test was statistically analysed by using the method of LH-moments for parameter estimation of the Weibull distribution. The root-mean-square errors (RMSEs) and the error of LH-kurtosis were used to examine the goodness-of-fit. The results for the first four LH-moments, the estimated parameters, and the probability distributions showed that the level of the LH-moments has a significant influence. At higher levels, the estimation results gave a more focused representation of the upper part of the wave crest distributions, which indicates consistency with the intention of the method of LH-moments. The low tail RMSE values of less than 2.5% demonstrated that a Weibull distribution model estimated by using high-level LH-moments can accurately represent the probability distribution of large extreme wave crests for incident waves, wave run-ups, and moon pool waves. Goodness-of-fit test on the basis of comparison of sampling LH-kurtosis and theoretical LH-kurtosis was recommended as a procedure for selecting an optimum level

COMPARATIVE HISTOLOGICAL ANALYSIS OF INTESTINES OF LOACH, GRASS CARP AND CATFISH PROVIDE INSIGHTS INTO ADAPTIVE CHARACTERISTICS IN AIR-BREATHING FISH

Općenito je prihvaćeno da su pomoćni dišni organi riba u više navrata samostalno evoluirali pri prilagođavanju slatkovodnim staništima i vodenoj hipoksiji. Vjeruje se da je organ za udisanje zraka kod riba strukturno modificiran kako bi nadopunio respiraciju. U ovom istraživanju prezentirani su intuitivni dokazi detaljne strukturne modifikacije crijeva i organa za udisanje zraka kod muljnog vijuna (Misgurnus anguillicaudatus), uspoređujući ih amurom (Ctenopharyngodon idellus) i žutim somom (Pelteobagrus fulvidraco). izravno dobiveni histološkom i morfometrijskom metodom. Kod muljnog vijuna očitovala se naglo smanjena visina nabora sluznice i debljina mišićnog sloja od prednjeg do stražnjeg dijela crijeva. U usporedbi sa amurom i žutim somom, vijun je imao i najmanji omjer visine nabora sluznice/debljine mišićnog sloja i polumjera crijeva u stražnjem dijelu crijevu. To sugerira da je moguće stražnji dio crijeva lokacija na kojoj vijun udiše zrak. Nadalje, gustoća kapilara (0,46 ± 0,05 μm-2) u zadnjem crijevu vijuna bila je značajno viša od amura i žutog soma. Također, difuzijska udaljenost zračno-krvne barijere (1,34 ± 0,04 μm) u stražnjem crijevu vijuna bila je značajno manja od one u druge dvije vrste riba. Ukratko, karakteristike poput visoke prokrvljenosti, kratke udaljenosti difuzije zračno-krvne barijere, prorijeđenosti i spljoštenosti, učinile su stražnji dio crijeva savršenom lokacijom za udisanje zraka istraživane vrste vijuna.Accessory respiratory is generally accepted to have evolved independently on numerous occasions in adaption to aquatic hypoxia in freshwater habitats. In general, the air-breathing organ in fish is believed to be structurally modified to supplement respiration. In this study, intuitive evidence for elaborate structural modifications of the intestine, an air-breathing organ in mud loach (Misgurnus anguillicaudatus), compared with two other obligate aquatic breathers, grass carp (Ctenopharyngodon idellus) and yellow catfish (Pelteobagrus fulvidraco), were directly provided by histological and morphometric methods. As a result, a sharply decreasing height of mucosal folds and thickness of muscularis were manifested in loach intestine from its anterior to posterior region. Compared with grass carp and yellow catfish, loach had the smallest ratios of mucosal fold height/muscularis thickness to intestinal lumen radius in the posterior intestine. These suggested that the posterior intestine is the air-breathing location for the loach. Furthermore, length density of capillary (0.46±0.05 μm-2) in the posterior intestine of the loach was significantly higher than those of grass carp and yellow catfish. Meanwhile, diffusion distance of air-blood barrier (1.34±0.04 μm) in the posterior intestine of the loach was significantly smaller than those of the other two fish species. In summary, the characteristics of highly vascularized, short diffusion distance of air-blood barrier, thinned and flattened made the posterior intestine a perfect air-breathing location for the loach

Flow around an oscillating circular disk at low to moderate Reynolds numbers

Direct numerical simulations of the flow induced by a circular disk oscillating sinusoidally along its axis are performed. The aspect ratio of the disk is 10. The Reynolds number , based on the maximum speed and the diameter of the disk, is in the range of . The Keulegan-Carpenter number is in the range of . Five flow regimes are observed in the considered-space: (I) axisymmetric flow (AS), (II) planar symmetric flow in the low-region (PSL), (III) azimuthally rotating flow in the low-region (ARL), (IV) planar symmetric flow in the high-region (PSH) and (V) azimuthally rotating flow in the high-region (ARH). The critical boundaries between different flow regimes are identified based on the evolutions of the magnitude and direction of transverse force acting on the disk. For the non-axisymmetric flow regimes, the flow is one-sided with respect to the axis of the disk and is associated with a non-zero mean value of the transverse force acting on the disk