Mid Channel Research Articles

A hue preservation lossless contrast enhancement method with RDH for color images

The contrast enhancement with reversible data hiding (CERDH) has become a hot topic in many fields. At present, most schemes applying CERDH methods to color images have the problem of color distortion. To solve this problem, this paper proposes a CERDH method for color images based on constant hue plane. It firstly separates the color images into min, mid and max channels. Then, a novel preprocessing is proposed to maintain the distribution of histogram for original image while vacate room for data hiding. After that, the mid channel is used for data hiding, and min and max channels are hue-preserved to avoid color distortion. Finally, the three channels compose a contrast-enhanced color image. The experimental results show that the proposed method achieves the best enhanced results based on CIEDE2000 compared with the state-of-the-art methods, and color distortion is also greatly reduced.

Improving the Scalability of Ferroelectric FET Nonvolatile Memories With High-k Spacers

This paper investigates scaled ferroelectric field-effect transistor (FeFET) nonvolatile memories (NVMs) with high-k spacer device design considering ferroelectric-dielectric random phase variations with TCAD atomistic simulations. Our study indicates that, in addition to raising the orthorhombic phase and reducing the grain size of the ferroelectric, using high-k spacers can serve as another way to enhance the scalability of FeFETs because it improves both the mean memory window (MW) and the worst-case MW. More importantly, these improvements increase with the down-scaling of gate length. In addition, we have investigated the impact of high-k spacers on the critical electric field across interfacial layer (EIL) for the reliability of FeFET NVMs. Our study suggests that, for scaled FeFETs with high-k spacers, the highest EIL during write operation is no longer located near the S/D edge but at the mid channel. Using high-k spacers can reduce the mid-channel EIL, and the reduction increases with decreasing gate length due to the increasing impact of high-k spacers. Our study may provide insights for future high-density FeFET design.

Growth and photo-electronic characteristics of short/mid wave dual-band infrared detectors based on GaSb bulk and InAs/GaSb superlattices

In this paper, we demonstrate a bias-selective short/mid wave dual-band infrared detector based on GaSb bulk materials and InAs/GaSb type-II superlattices with 50% cutoff wavelengths of 1.55 μm and 4.62 μm, respectively. At 77 K, the short wave channel exhibited a peak quantum efficiency of 35.86% at 1.43μm and a dark current density of 8.41 × 10−5A/cm2 under the forward 5.0 V bias, thereby providing a Johnson-noise-limited detectivity of 7.63 × 1011cm · Hz1/2/W. The mid-wave channel showed a quantum efficiency of 10.45% at 4.0μm and dark current density of 4.17 × 10−3A/cm2 under -1.35 V bias, resulting in a detectivity of4.05 × 1010cm · Hz1/2/W. The cross-talk was very low in the short wave channel, but existed in the mid wave channel originated from the contribution of the residual built-in electric field in the short wave channel. Furthermore, the schematic band alignment of N-I-P-P-I-N back-to-back structure was also discussed for further optimization.

Detonation propagation across a stratified layer with a diffuse interface

A study was conducted to examine detonation propagation in a stratified layer of hydrogen-oxygen-nitrogen above an inert gas in a horizontal narrow channel. The stratified layer was produced by a gravity current, generated by retracting a door initially separating a hydrogen-oxygen-nitrogen mixture in the predetonator and a heavier inert gas in the test-section. A steady detonation wave generated in the predetonator was transmitted into the stratified layer. The reactivity of the predetonator mixture was varied via the hydrogen-oxygen equivalence ratio and the amount of nitrogen dilution. Schlieren photography was used to visualize the detonation front in the test-section, and soot foils were used to obtain the cellular structure. Schlieren imaging showed a curved detonation front that decoupled at about mid channel height, into a shock wave and trailing contact surface. Both the hydrogen-oxygen-nitrogen reactivity and the type of inert gas initially in the test-section affected the distance travelled by the detonation wave in the stratified layer. The mixture composition distribution within the test-section before ignition was obtained via a three-dimensional CFD simulation. The lateral extent of the cellular structure captured on the soot foil, coincided with the calculated inert gas mole fraction contour that corresponds to a sharp increase in the ZND induction zone length, e.g., 70% argon dilution for a stoichiometric hydrogen-oxygen predetonator mixture.

Investigation of Coherent Flow Turbulence in the Proximity of Mid-Channel Bar

The turbulent flow characteristics in the vicinity of mid-channel bar are studied in this paper. The velocity is measured with the help of the acoustic Doppler velocimetry (ADV). Fractal modelling is done for analysing the fractal nature of bursting events. The conditional Reynolds stress structure was analysed by using the quadrant technique. Decomposition of Reynolds stress help in studying the distribution of stress among the four quadrants. The hole-size concept is utilized for segregating the extreme bursting events from the low intensity events. Variation of quadrants stresses with the hole-size is analysed. The result of hole-size study indicates that the extreme turbulent burst is produced by the mid channel bar. The new parameter inclination ratio is evolved in this research to reflect streambed elevation changes. The results indicate that the high-level turbulence is generated at region near upstream end of mid-channel bar. The presence of mid-channel bar causes the critical changes to the turbulent structure of flow, where high Reynolds stresses are generated at region near upstream region of mid-channel bar. Third order moments are computed for vertical lines in the proximity of mid-channel bar. High value of third order moments for bar condition indicate that the intense turbulent mixing and momentum exchange take place.

Erratum

Previous article FreeErratumOriginal articleDefining freshwater mussel mesohabitat associations in an alluvial, Coastal Plain riverPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreIn the article by Smit and Kaiser, published in the December 2016 issue of Freshwater Science (35:1276–1290), the original Fig. 4 (on page 1284) contained y values of the natural log of total mussel density, whereas the y-axis label suggested values of log base 10. The figure was corrected to contain y values of log base 10 to agree with the y-axis label. The authors regret the error.Figure 4. Box-and-whisker plots illustrating the distribution of total density of mussels collected within each of the 5 mesohabitat classes. Lines in boxes are medians, box ends are quartiles, and whiskers show ranges. Boxes with the same letters are not significantly different. IRZ = inner recirculation zone, MC = mid channel, ORZ = outer recirculation zone, PB = point bar, and POB = pool/outer bend.View Large ImageDownload PowerPoint Previous article DetailsFiguresReferencesCited by Freshwater Science Volume 38, Number 1March 2019 Published on behalf of the Society for Freshwater Science Article DOIhttps://doi.org/10.1086/703247 © 2019 by The Society for Freshwater Science.PDF download Crossref reports no articles citing this article.Related articlesDefining freshwater mussel mesohabitat associations in an alluvial, Coastal Plain river15 Sep 2016Freshwater Science

A Robust Digital Image Watermarking in Hybrid Frequency Domain

Image watermarking is a method to hide the secret information in a host image for copyright protection of watermark data during the transmission by means of insecure channel. The proposed scheme protects our data with adaptive level of visual quality and robustness against signal processing and geometric attacks. The proposed method divides the host image into four non-overlapping segments labelled as sub-images, DWT is applied on each sub images and then block based DCT is applied on mid frequency channels LH and HL of discrete wavelet transform. Embedded matrix is formed using hybrid transformed coefficients where matrix elements are chosen from the localized two mid frequency coefficients of each block in DCT. SV Decomposition is applied on embedded matrix to factorize it into singular values, left and right singular vectors and embed the scrambled watermark image along with scaling factor in singular value matrix. This repetition of watermark data in each sub-image reduces the PSNR values of the watermarked image. Despite this proposed scheme scales down PSNR value, changing the scaling factor favours to adjust the PSNR to the acceptable level and withstand the signal processing attacks such as JPEG compression and geometrical attack such as rotation, translation. Compared to the other method, the proposed scheme gives better correlation coefficient value for above mentioned kinds of attacks and also provide adaptive PSNR for imperceptibility on watermarked image.

Examining diffusion to understand the how of SASA!, a violence against women and HIV prevention intervention in Uganda

BackgroundA growing number of complex public health interventions combine mass media with community-based “change agents” and/or mobilisation efforts acting at multiple levels. While impact evaluations are important, there is a paucity of research into the more nuanced roles intervention and social network factors may play in achieving intervention outcomes, making it difficult to understand how different aspects of the intervention worked (or did not). This study applied aspects of diffusion of innovations theory to explore how SASA!, a community mobilisation approach for preventing HIV and violence against women, diffused within intervention communities and the factors that influenced the uptake of new ideas and behaviours around intimate partner relationships and violence.MethodsThis paper is based on a qualitative study of couples living in SASA communities and secondary analysis of endline quantitative data collected as part of a cluster randomised control trial designed to evaluate the impact of the SASA! intervention. The primary trial was conducted in eight communities in Kampala, Uganda between 2007 and 2012. The secondary analysis of follow up survey data used multivariate logistic regression to examine associations between intervention exposure and interpersonal communication, and relationship change (n = 928). The qualitative study used in-depth interviews (n = 20) and framework analysis methods to explore the intervention attributes that facilitated engagement with the intervention and uptake of new ideas and behaviours in intimate relationships.ResultsWe found communication materials and mid media channels generated awareness and knowledge, while the concurrent influence from interpersonal communication with community-based change agents and social network members more frequently facilitated changes in behaviour. The results indicate combining community mobilisation components, programme content that reflects peoples’ lives and direct support through local change agents can facilitate diffusion and powerful collective change processes in communities.ConclusionsThis study makes clear the value of applying diffusion of innovations theory to illuminate how complex public health intervention evaluations effect change. It also contributes to our knowledge of partner violence prevention in a low-income, urban East African context.Trial registrationClinicalTrials.gov #NCT00790959. Registered 13th November 2008.

Acoustically derived habitat associations of sympatric invasive bigheaded carps in a large river ecosystem

AbstractBigheaded carp (Hypophthalmichthys spp.) occur throughout much of the Mississippi Basin, USA. Efforts to control the spread of these invasive species require information on their spatial ecology, though sampling is hindered by their broad extent, habitat tolerances, and species‐specific behaviour. Mobile hydroacoustics was used to quantify habitat and depth use of bigheaded carp over four years in the heavily invaded Lower Illinois River, a major Mississippi tributary and potential dispersal pathway to the Great Lakes. Horizontally oriented transducers (combined with capture gear for species designation) enabled sampling of the main habitat features in this large flood plain river. Silver carp (Hypophthalmichthys molitrix) were dominant over bighead carp (Hypophthalmichthys nobilis) at all but one site, although habitat use was similar for both species. Densities were highest in lotic backwaters, followed by lentic backwaters and nearshore main channel, with lowest densities in the mid main channel. Bigheaded carp size and species composition were independent of habitat type. Depth associations were similar for both species, with average occurrence at 2.5–3.5 m in the main channel and 1–2 m in backwaters. However, depth relative to the river bed was largely similar across habitat types. Bigheaded carp density and depth use in the main channel were linked non‐linearly to river discharge and water temperature, respectively; densities were reduced during high discharge, whereas depth use became shallower at higher temperatures. Density–hydrology trends were less apparent in backwaters. These findings highlight critical aspects of bigheaded carp spatial ecology that will facilitate effective management in invaded and at‐risk ecosystems.

The Mediterranean Overflow in the Gulf of Cadiz: A rugged journey.

The pathways and transformations of dense water overflows, which depend on small-scale interactions between flow dynamics and erosional-depositional processes, are a central piece in the ocean's large-scale circulation. A novel, high-resolution current and hydrographic data set highlights the intricate pathway travelled by the saline Mediterranean Overflow as it enters the Atlantic. Interaction with the topography constraints its spreading. Over the initial 200 km west of the Gibraltar gateway, distinct channels separate the initial gravity current into several plunging branches depth-sorted by density. Shallow branches follow the upper slope and eventually detach as buoyant plumes. Deeper branches occupy mid slope channels and coalesce upon reaching a diapiric ridge. A still deeper branch, guided by a lower channel wall marked by transverse furrows, experiences small-scale overflows which travel downslope to settle at mid-depths. The Mediterranean salt flux into the Atlantic has implications for the buoyancy balance in the North Atlantic. Observations on how this flux enters at different depth levels are key to accurately measuring and understanding the role of Mediterranean Outflow in future climate scenarios.

Detection of memory loss of symmetry in the blockage of a turbulent flow within a duct

This paper aims to detect memory loss of the symmetry of blockades in ducts and how far the information on the asymmetry of the obstacles travels in the turbulent flow from computational simulations with OpenFOAM. From a practical point of view, it seeks alternatives to detect the formation of obstructions in pipelines. The numerical solutions of the Navier–Stokes equations were obtained through the solver PisoFOAM of the OpenFOAM library, using the large Eddy simulation (LES) for the turbulent model. Obstructions were placed near the duct inlet and, keeping the blockade ratio fixed, five combinations for the obstacles sizes were adopted. The results show that the information about the symmetry is preserved for a larger distance near the ducts wall than in mid-channel. For an inlet velocity of 5[Formula: see text]m/s near the walls the memory is kept up to distance 40 times the duct width, while in mid-channel this distance is reduced almost by half. The maximum distance in which the symmetry breaking memory is preserved shows sensitivity to Reynolds number variations in regions near the duct walls, while in the mid channel that variations do not cause relevant effects to the velocity distribution.

Occurrence and genetic characterisation of Acanthamoeba spp. from environmental and domestic water sources in Queen Elizabeth Protected Area, Uganda.

BackgroundAcanthamoeba is an emerging potentially pathogenic amoeba that has been receiving increasing attention worldwide as a reservoir and potential vector for the transmission of pathogenic bacteria. It is also associated with brain cell damage, keratitis and skin irritation in humans. Its effects are more severe in immunocompromised individuals. This study provides for the first time in Uganda, information on the prevalence and genotypes of Acanthamoeba in environmental and domestic (tap) water.MethodsA total of 324 environmental and 84 tap water samples were collected between November 2013 and September 2014. The samples were centrifuged, cultured (Non-Nutrient agar seeded with gram-negative bacteria) and observed under a microscope. After confirmation of Acanthamoeba, genomic DNA was extracted for PCR assays by chemical lysis and purification with phenol/chloroform/isoamyl alcohol. Samples that showed the strongest positive bands (400–600 bp) were subjected to cycle sequencing.ResultsAmong environmental and tap water samples, 107 (33 %) and 36 (42.9 %) tested positive for Acanthamoeba spp., respectively. Prevalence of Acanthamoeba from specific environmental locations was as follows; Kazinga channel banks (60.7 %), Fish landing sites (50 %), River Kyambura (39.6 %) and Kazinga mid channel (5.3 %). There was a significant difference (p = 0.001) in the prevalence of Acanthamoeba between sampling sites. The mean (Mean ± SE) occurrence of the organism was higher in Kazinga channel banks (3.44 ± 0.49) and Fish landing sites (3.08 ± 0.53). Correlation between in situ parameters and Acanthamoeba was insignificant except for the Dissolved Oxygen (mg/ML) which was negatively correlated (r = −0.231, p = 0.001) to Acanthamoeba. Six distinct partial Acanthamoeba T-genotype groups T1, T2, T4, T5, T6 and T11 were obtained. Ultimately, Acanthamoeba spp., Acanthamoeba hatchetti and Acanthamoeba polyphaga were isolated in the current study.ConclusionsThere was a high prevalence of Acanthamoeba in communal piped tap and environmental water used by communities, indicating poor environmental and domestic water quality.

On radial flow between parallel disks

Approximate analytical solutions are presented for converging flow in between two parallel non rotating disks. The static pressure distribution and radial component of the velocity are developed by averaging the inertial term across the gap in between parallel disks. The predicted results from the first approximation are favourable to experimental results as well as results presented by other authors. The second approximation shows that as the fluid approaches the center, the velocity at the mid channel slows down which is due to the struggle between the inertial term and the flowrate.

High spatial variability of phytoplankton assessed by flow cytometry, in a dynamic productive coastal area, in spring: The eastern English Channel

The distribution of phytoplankton (from pico-to microphytoplankton) was investigated, at single-cell level and at high spatial resolution, during an oceanographic cruise across the eastern English Channel (EEC) between April 27 and 29, 2012. Seawater was continuously collected from surface waters and analysed on board at high frequency (one sample every 10 min), by using a new generation of pulse-shape recording scanning flow cytometer (CytoSense, Cytobuoy©). A Bray–Curtis matrix analysis based on phytoplankton composition allowed the discrimination of 4 communities. Within these communities, abundance, cell size as well as single cell and total red fluorescence of 8 phytoplankton groups were measured. Picoeukaryotes and Synechococcus spp cells dominated the mid Channel and most of the English waters monitored, whereas waters off Eastbourne as well as French coastal waters (under remote and direct estuarine influence) were characterized by the dominance of Phaeocystis globosa haploid and diploid cells. Most of the total red fluorescence signal, which correlated with chlorophyll a concentrations, was attributable to P. globosa and, to a lesser extent, to diatoms. In addition to sub-mesoscale variation within phytoplankton communities, the single-cell features within each phytoplankton group gave information about the physiological status of individual phytoplankton cells.

Some experimental studies on angle effect in penetration

This investigation describes and analyses the experimental results pertinent to the penetration of Al-7017 plates with non-deformable steel projectiles at a velocity of 840 ± 15 m/s at different angles of impact. The results include the variation in damage pattern, damage area at front and back, mid penetration channel observations, residual velocity and energy absorption capacities at different obliquities. Some observations relating to the adiabatic shear bands formation have also been presented. The micro hardness values along the path of penetration have been studied in order to understand the increase in energy absorption at oblique impact. The experimental data shows a transition of failure mode from an adiabatic shear band induced shear plugging at lower obliquities to a more homogeneous deformation of the target material and gouging at higher obliquities.

The Paleogene record of Himalayan erosion: Bengal Basin, Bangladesh

A knowledge of Himalayan erosion history is critical to understanding crustal deformation processes, and the proposed link between the orogen's erosion and changes in both global climate and ocean geochemistry. The most commonly quoted age of India–Asia collision is ~50 Ma, yet the record of Paleogene Himalayan erosion is scant — either absent or of low age resolution. We apply biostratigraphic, petrographic, geochemical, isotopic and seismic techniques to Paleogene rocks of the Bengal Basin, Bangladesh, of previously disputed age and provenance. Our data show that the first major input of sands into the basin, in the >1 km thick deltaic Barail Formation, occurred at 38 Ma. Our biostratigraphic and isotopic mineral ages date the Barail Formation as spanning late Eocene to early Miocene and the provenance data are consistent with its derivation from the Himalaya, but inconsistent with Indian cratonic or Burman margin sources. Detrital mineral lag times show that exhumation of the orogen was rapid by 38 Ma. The identification of sediments shed from the rapidly exhuming southern flanks of the eastern–central Himalaya at 38 Ma, provides a well dated accessible sediment record 17 Myr older than the previously described 21 Ma sediments, in the foreland basin in Nepal. Discovery of Himalayan detritus in the Bengal Basin from 38 Ma: 1) resolves the puzzling discrepancy between the lack of erosional evidence for Paleogene crustal thickening that is recorded in the hinterland; 2) invalidates those previously proposed evidences of diachronous collision which were based on the tenet that Himalayan-derived sediments were deposited earlier in the west than the east; 3) enables models of Himalayan exhumation (e.g. by mid crustal channel flow) to be revised to reflect vigorous erosion and rapid exhumation by 38 Ma, and 4) provides evidence that rapid erosion in the Himalaya was coincident with the marked rise in marine 87Sr/86Sr values since ~40 Ma. Whether 38 Ma represents the actual initial onset of vigorous erosion from the southern flanks of the east-central Himalaya, or whether older material was deposited elsewhere, remains an open question.

Assessing the biomass of small fish with a split-beam sonar in the Murray River, Australia

Split-beam hydroacoustics revealed large numbers of small fish in the lower reaches of the Murray River in autumn. At slow-flow sites, acoustically estimated fish biomass could reach 102 kg/ha in mid channel, which compares with the biomass level of planktivorous fish in eutrophic lakes. These results were confirmed by direct catches with a push net of Australian smelt ( Retropinna semoni) and juvenile bony herring ( Nematalosa erebi) ranging in length from 18 to 150 mm. Fish densities in the river channel doubled at night compared to the day. The density and total biomass estimates from net catches were strongly correlated with the acoustic data. However, the catch estimates were only 50–60% of the acoustic measurements, which is explained by the limited netting efficiency. The two methods produced similar estimates of fish mean weights. These results suggest that the density and biomass of small fish in open water habitats of the river can be reliably determined with acoustics. The high biomass of planktivorous fish and the diverse zooplankton community found in the same habitat suggest that the fish probably exploit an advantageous ecological niche in the main channel of the Lower Murray. The high biomass of small fish in this reach of the river, which has previously been underestimated, provides a large potential food source for native predators.

WHITE-CLAWED CRAYFISH IN MUDDY HABITATS: MONITORING THE POPULATION IN THE RIVER IVEL, BEDFORDSHIRE, UK

White-clawed crayfish Austropotamobius pallipes are usually associated with stony substrates, tree roots, or refuges in submerged banks. The River Ivel has the last known population of white-clawed crayfish in Bedfordshire. Prior to 2005, much of the bed comprised uniform silt, plus leaf-litter. Stands of reedmace Typha latifolia and other emergent vegetation were localised in less shaded areas. Initial survey results suggested a population at low abundance. A low-cost monitoring strategy was started in 2001 and continued three times a year to 2005, using engineering bricks, which offer artificial refuges. Crayfish are counted when bricks are lifted periodically. De-silting of c. 430 m river was carried out in February 2005, to improve habitat and to maintain the flood capacity in the channel upstream of a mill weir. Additional bricks were deployed a few weeks in advance of de-silting, then bricks and crayfish were lifted prior to dredging and were returned the next day. Starting upstream, soft, wet mud was dredged out, placed on the bank and searched manually for crayfish. Banks, tree roots and shallow margins were left undisturbed. In all, 4,142 crayfish were found in dredgings from a 430 m length of the mid channel. Crayfish were strongly associated with emergent vegetation, but many were present below the surface of the silt. Crayfish released in the dredged channel immediately burrowed into the silt retained on the channel margins. Monitoring after dredging showed no change in abundance in the main area with in-bank refuges and lots of bricks, but there was an increase in occupancy of bricks in an area where most crayfish had been in emergent vegetation.

MUTUAL EFFECTS OF BED AND BANK DEFORMATION IN CHANNEL PLANE FORMATION

A numerical model is developed to simulate the formation of braided stream, in which bank erosion and bed deformation are calculated simultaneously. Flow field, bed deformation, bank erosion and channel geometry are calculated numerically with a general coordinate system, which can be applied to any shape of channel geometry during the deformation of channel geometry due to the bank erosion. Calculation is started with a narrow straight channel with fiat bed, and in tern the development of alternate bar, channel meandering, appearance of mid channel bar, and finally, a braided channel geometry is simulated. Computational results are favorably compared with experimental. The mutual effect of bank and bed defoemation to the channel plane geometry is disscused.

Seasonal changes of fish diversity in the main channel of the large lowland River Oder

Between June 1998 and May 2000 an adult fish sampling was carried out in the lowland River Oder using bottom otter trawls in the mid channel and electric fishing at the shorelines. This study focused on the lateral connectivity between mid channel and river margins with the aim to characterize the importance of mid-channel sections as fish habitat. Altogether 15 660 fish of 30 species were sampled, 8169 fish of 20 species in the mid-channel section and 7491 fish of 27 species at the shoreline. At the shoreline we observed significantly higher fish densities (345.4±51.8 fish per 1000 m3 compared to 5.2±1.0, mean±standard error) and numbers of species (11.1±0.5, respectively, 5.2±0.3). However, three species were exclusively in the mid channel and a further six more frequent there. The mid channel was dominated by silver bream (Abramis bjoerkna) representing 75.6% of the total catch. It was generally colonized by bigger fish (22.1±0.12 cm total length compared to 13.0±0.08 cm). According to the observed significant habitat preferences, we classified a guild of potamal species, which shift during their first year of life to mid-channel habitats and exhibited the highest relative abundance there. To this guild belong the following species: silver bream, common bream (Abramis brama), blue bream (Abramis ballerus), whitefin gudgeon (Gobio albipinnatus), zander (Sander lucioperca) and wels (Silurus glanis). Copyright © 2001 John Wiley & Sons, Ltd.