Breaking Region Research Articles

Stress analysis of a Wankel engine eccentric shaft under varied thermal conditions

AbstractIn this study, the eccentric shaft of a 13B MSP (Multi Side Port) single-rotor Wankel test engine was examined. The eccentric shaft was studied in two parts, both through modeling and experimentally. The eccentric shaft was modeled via a workbench module using ANSYS software. Here, the shaft was modeled according to the original dimensions at different speeds ranging from 1000 to 10000 rpm under different operating temperatures (25, 50 and 90 °C). In the analysis, von Mises stress and corresponding deformations were examined under the specified conditions. Afterwards, the stress and deformation of the eccentric shaft were experimentally investigated in engine tests performed at low loads and speeds. The eccentric shaft broke after approximately 200 hours. It was found that broken region was specified to critical points for validity of the applied model used in the current study. Thus, it was shown deformation and stress values can be predicted by numerically modeling the eccentric shaft with the help of ANSYS software in order to determine whether the eccentric shaft can withstand external loading under various conditions.

Laboratory Observation of Turbulence and Wave Shear Stresses Under Large Scale Breaking Waves Over a Mild Slope

AbstractLaboratory measurements of turbulent flow and shear stresses in a surf zone under monochromatic breaking waves in a large‐scale wave flume are presented. Waves with various surf similarity parameters were generated to break at nearly identical water depths over a 1/100 mild slope. Free surface elevations were measured along the plane beach. Velocities in a water column located at the breaking region were measured by acoustic Doppler velocimeters. Results from wave shoaling coefficient, breaking index, and images are inconsistent with the breaker type categorizations from the surf similarity parameter. This suggests that a modification of the surf similarity parameter for very mild slopes may be necessary. For the plunging breakers, the ensemble‐averaged results indicate that intense turbulence kinetic energy was initially generated by large eddies at the surface then transported to the bottom frequently. The instantaneous results demonstrate that the intermittency of turbulence kinetic energy near the bed was caused by large eddies generated by wave overturning and relatively smaller obliquely descending eddies. Moreover, the magnitude of the wave shear stress (WSS) is one order of magnitude larger than that of the turbulent shear stress, indicating that the effects of the bottom slope, wave breaking, and bed friction are significant in the surf zone. The sign of the time‐averaged WSS switched between positive and negative, depending on the occurrences of phase lag and phase lead of the vertical coherent velocity. It suggests that a change may be required in Zou et al.'s (2006, https://doi.org/10.1029/2005JC003300) theory on the formulation of wave‐breaking induced WSS.

Long range intensity fluctuations on the Chukchi continental shelf measured during the year-long Canada Basin Acoustic Propagation Experiment 2017

Analysis of one-year-long broadband transmissions from five deep water sound sources recorded on shelf during the Canada Basin Acoustic Propagation shows strong azimuthal variability. Broadband chirp signals (140–325 Hz) transmitted every 4 h were received on spatially distributed receiver arrays on the Chukchi shelf from October 2016 through 2017. Here, we present spatial, temporal, and azimuthal correlations by four receiver arrays with source-receiver distances ranging from 228.6 to 524.4 km in a cross-the-shelf orientation. Temporal fluctuations in received field are related to water column variability for each source-receiver pair. Received signals from the same source to each receiver on the shelf, separated from 15.8 to 49.63 km in “along-the-shelf” direction show large intensity fluctuation. This is related to the turbulence that signals have experienced in their path. Temporal and spatial variations of temperature profiles were measured on the shelf, however, from deep water sources to the shelf break region, there is little information. Analysis are conducted for three time zones, from fully frozen seas, transition from full ice, and ice-free conditions. The parabolic equation model is used to report the propagation of field for the ice-free condition. Limitations of the acoustic modeling due to spatially under-sampled input environmental parameters are discussed. [Work supported by ONR-322 OA.]Analysis of one-year-long broadband transmissions from five deep water sound sources recorded on shelf during the Canada Basin Acoustic Propagation shows strong azimuthal variability. Broadband chirp signals (140–325 Hz) transmitted every 4 h were received on spatially distributed receiver arrays on the Chukchi shelf from October 2016 through 2017. Here, we present spatial, temporal, and azimuthal correlations by four receiver arrays with source-receiver distances ranging from 228.6 to 524.4 km in a cross-the-shelf orientation. Temporal fluctuations in received field are related to water column variability for each source-receiver pair. Received signals from the same source to each receiver on the shelf, separated from 15.8 to 49.63 km in “along-the-shelf” direction show large intensity fluctuation. This is related to the turbulence that signals have experienced in their path. Temporal and spatial variations of temperature profiles were measured on the shelf, however, from deep water sources to the shelf ...

Consistent nonlinear deterministic and stochastic wave evolution equations from deep water to the breaking region

Modelling the evolution of the wave field in coastal waters is a complicated task, partly due to triad nonlinear wave interactions, which are one of the dominant mechanisms in this area. Stochastic formulations already implemented into large-scale operational wave models, whilst very efficient, are one-dimensional in nature and fail to account for the majority of the physical properties of the wave field evolution. This paper presents new two-dimensional (2-D) formulations for the triad interactions source term. A quasi-two-dimensional deterministic mild slope equation is improved by including dissipation and first-order spatial derivatives in the nonlinear part of equation, significantly enhancing the accuracy in the breaking zone. The newly defined deterministic model is used to derive an updated stochastic model consistent from deep waters to the breaking region. It is localized following the approach derived in Vrecica & Toledo (J. Fluid Mech., vol. 794, 2016, pp. 310–342), to which several improvements are also presented. The model is compared to measurements of breaking and non-breaking spectral evolution, showing good agreement in both cases. Finally, the model is used to analyse several interesting 2-D properties of the shoaling wave field including the evolution of directionally spread seas.

Bumpy Topographic Effects on the Transbasin Evolution of Large‐Amplitude Internal Solitary Wave in the Northern South China Sea

AbstractThe bumpy continental slope/shelf topography is a quite common feature in the northern South China Sea (SCS), yet its effect on the shoaling internal solitary waves (ISWs) remains poorly understood. Therefore, numerical simulations by a fully nonlinear, nonhydrostatic model are carried out to explore the bumpy continental slope/shelf topographic effects on the transbasin evolution of large‐amplitude ISW in the northern SCS. It is found that the prominent bumps over both continental slope and shelf regions play significant roles in modulating the evolution of transbasin ISW in the northern SCS. The bump over the continental slope is capable of triggering a solitary‐like mode‐2 internal wave packet, while the bump over the continental shelf can result in three wave groups, including a leading group of rank‐ordered mode‐1 ISW packet and two following groups of non‐rank‐ordered mode‐1 ISW packet and mode‐2 internal waves. The bumps can cause a peak‐to‐peak difference of the energy decay rate of ISW up to 10–20 kW/m over continental slope region and 3–5 kW/m over continental shelf region. The wave kinetic energy (KE) is found to exceed the available potential energy (APE) by as much as 50% over the continental shelf break region. Over the shelf region, however, the bumps can first make the KE drop to as low as only 80% of the APE, but later the KE might bounce back to approximately 1.1–1.2 times of the APE. Both onshore‐ and offshore‐propagating beam‐like disturbances are found to be excited by the bumps. Except for the onshore‐propagating mode‐2 ISW packet, the reflected offshore‐propagating waves in different internal modes are also formed. These onshore‐ and offshore‐propagating multimodal internal waves can be clarified by the beam scattering and local generation mechanism.

Vertical Structure of the Water Column at the Virgin Islands Shelf Break and Trough

The steep US Virgin Islands Shelf Break (VISB) and the Virgin Islands Trough (VIT) at the Northeastern Caribbean Sea comprise a dynamic region of the Atlantic Ocean. In situ oceanographic data collected in the region during April 2017 were used to examine the spatial variability in temperature, density, salinity, and relative Chlorophyll-a. Analysis of data from the upper 300 m of the water column, that include deep and shallow water stations in the shelf break region, shows strong stratification of the water column. Stations shallower than 800 m along the shelf break are more variable in temperature, density, and salinity than those that are deeper than 800 m along the trough. For shallow stations, the mixed layer depth deepens along-shelf from West to East while at the deep stations the opposite occurs. Salinity maxima exhibit more variability in depth and range of values in the shallow stations compared to deep stations. Six different types of water masses that contribute to the strong stratification in the region were identified in our study: Caribbean Surface Water, Subtropical Underwater, Sargasso Sea Water, Tropical Atlantic Central Water, Antarctic Intermediate Water, and North Atlantic Deep Water. The upper level Caribbean Surface Water, Subtropical Underwater, and Sargasso Sea Water are present in shallow stations, indicating potential meridional intrusions from the VIT to the VISB which may not be resolved by current ocean circulation models and are not captured in satellite data. The analysis presented here indicates that competing physical processes may be controlling the vertical structure of the water column in the region and merit further examination.

Molecular biology of sarcoma

Soft tissue sarcomas are a large group of heterogenous neoplasms, many of them are highly aggressive. Most of the cases are sporadic, without any well-defined pathogenetic factor. Potential risk factors are ionizing radiation, lymphatic oedema (secondary angiosarcoma of the breast), viral infections (HHV8 and Kaposi sarcoma), exposure to chemical factors (vinyl chloride and hepatic angiosarcoma). Genetic susceptibility plays a role in a minority of cases. However, mutations in TP53, ATM and ATR genes are associated with enhanced susceptibility to radiation. Li-Fraumeni syndrome (autosomal dominant TP53 mutation) predisposes to development of malignancies, one third of them are sarcomas. Genetic alterations observed in sarcomas could be divided into three major groups characterized by: (1) chromosome translocations; (2) simple karyotype and mutations; (3) variably complex karyotypes. A large part of sarcomas belong to the first group and the specific chromosal translocations could be utilized in the diagnostic process. A smaller number of sarcomas could be assigned to the second group, e.g. desmoid fibromatosis (CTNNB1 or APC mutations) and GIST (KIT, PDGFRA, or less frequently BRAF, SDH, NF1). A large number of sarcomas are characterized by complex and variable karyotypes. Gene copy number alterations are frequent in this group, e.g. in well-differentiated liposarcoma there is an amplification of MDM2, CDK4 and HMGA2 genes or sarcoma-specific chromosomal break regions present in the CHOP gene in myxoid liposarcoma and FKHR in alveolar rhabdomyosarcoma.

The distribution of deep-sea sponge aggregations (Porifera) in relation to oceanographic processes in the Faroe-Shetland Channel

Deep-sea sponge aggregations have been identified as potential Vulnerable Marine Ecosystems under United Nations General Assembly Resolution 61/105. Understanding the distribution of these habitats is critical to future spatial management efforts, and central to this understanding are quantitative data on the environmental drivers of that distribution. Accumulations of large suspension feeders are hypothesised to aggregate in regions of internal wave formation. The causal link is thought to be an increase in the supply of food related to the incidence of internal waves, which results in resuspension of particulate organic matter on which the sponges feed. There is, however, almost no empirical evidence to support this hypothesis for deep-sea sponge aggregations, although there is strong circumstantial evidence. We tested the relationship between sponge density and 1) temperature range (as a measure of internal wave presence in this region), and 2) optical backscatter (a measure of particulate flux) for a known sponge aggregation in the Faroe-Shetland Channel where internal wave interaction with the slope is further well-documented. 25 benthic video transects, ranging from 422 to 979 m water depth were conducted in the study region. 225 images were analysed and all taxa identified to morphotypes and quantified. Temperature and optical backscatter data were drawn from archived CTD data, and data from long term (4 months) and 2 seasonal short term (11 days) mooring deployments from the region. A generalised linear model was used to test the relationship between sponge density and temperature range (ΔT), and sponge density and optical backscatter. The results showed a statistically significant positive relationship between sponge density and temperature range, with the highest sponge densities occurring at depths of greatest temperature range. They showed a statistically significant positive relationship between sponge density and optical backscatter for long term and one short term seasonal deployment (Sep–Oct), but a weak negative relationship for the other short term mooring deployment (April-May). We conclude that sponge aggregations in the Faroe-Shetland Channel are associated with slope regions that are subjected to abrupt and pronounced changes in temperature due to intensified internal wave activity over the slope between depths of 400–600 and that lead to intensified near-bed currents and elevated resuspension of particulate. Our data provide empirical evidence of the relationship between internal wave processes and deep-sea sponge aggregations. These data modify current theory on drivers of deep sea sponge aggregation distribution, suggesting aggregations also occur directly within regions of internal wave breaking, rather than simply proximal to these regions.

J-PLUS: The Javalambre Photometric Local Universe Survey

The Javalambre Photometric Local Universe Survey (J-PLUS ) is an ongoing 12-band photometric optical survey, observing thousands of square degrees of the Northern Hemisphere from the dedicated JAST/T80 telescope at the Observatorio Astrofísico de Javalambre (OAJ). The T80Cam is a camera with a field of view of 2 deg2 mounted on a telescope with a diameter of 83 cm, and is equipped with a unique system of filters spanning the entire optical range (3500–10 000 Å). This filter system is a combination of broad-, medium-, and narrow-band filters, optimally designed to extract the rest-frame spectral features (the 3700–4000 Å Balmer break region, Hδ, Ca H+K, the G band, and the Mg b and Ca triplets) that are key to characterizing stellar types and delivering a low-resolution photospectrum for each pixel of the observed sky. With a typical depth of AB ∼21.25 mag per band, this filter set thus allows for an unbiased and accurate characterization of the stellar population in our Galaxy, it provides an unprecedented 2D photospectral information for all resolved galaxies in the local Universe, as well as accurate photo-z estimates (at the δ z/(1 + z)∼0.005–0.03 precision level) for moderately bright (up to r ∼ 20 mag) extragalactic sources. While some narrow-band filters are designed for the study of particular emission features ([O II]/λ3727, Hα/λ6563) up to z < 0.017, they also provide well-defined windows for the analysis of other emission lines at higher redshifts. As a result, J-PLUS has the potential to contribute to a wide range of fields in Astrophysics, both in the nearby Universe (Milky Way structure, globular clusters, 2D IFU-like studies, stellar populations of nearby and moderate-redshift galaxies, clusters of galaxies) and at high redshifts (emission-line galaxies at z ≈ 0.77, 2.2, and 4.4, quasi-stellar objects, etc.). With this paper, we release the first ∼1000 deg2 of J-PLUS data, containing about 4.3 million stars and 3.0 million galaxies at r < 21 mag. With a goal of 8500 deg2 for the total J-PLUS footprint, these numbers are expected to rise to about 35 million stars and 24 million galaxies by the end of the survey.

Spatial and temporal distributions of turbulence under bichromatic breaking waves

The present study aims to extend insights of surf zone turbulence dynamics to wave groups. In a large-scale wave flume, bichromatic wave groups were produced with 31.5 s group period, 4.2 s mean wave period, and a 0.58 m maximum wave height near the paddle. This condition resulted in plunging-type wave breaking over a fixed, gravel-bed, barred profile. Optic, acoustic and electromagnetic instruments were used to measure the flow and the spatial and temporal distributions of turbulent kinetic energy (TKE). The measurements showed that turbulence in the shoaling region is primarily bed-generated and decays almost fully within one wave cycle, leading to TKE variations at the short wave frequency. The wave breaking-generated turbulence, in contrast, decays over multiple wave cycles, leading to a gradual increase and decay of TKE during a wave group cycle. In the wave breaking region, TKE dynamics are driven by the production and subsequent downward transport of turbulence under the successive breaking waves in the group. Consequently, the maximum near-bed TKE in the breaking region can lag the highest breaking wave by up to 2.5 wave cycles. The net cross-shore transport of TKE is in the shoaling region primarily driven by short-wave velocities and is shoreward-directed; in the wave breaking region, the TKE transport is seaward-directed by the undertow and the long-wave velocities. Downward transport of TKE is driven by the vertical component of the time-averaged flow. The cross-shore and vertical diffusive transport rates are small relative to the advective transport rates.

Local nonlinear dynamics of MEMS arches actuated by fringing-field electrostatic actuation

The nonlinear dynamic behavior of a resonant MEMS arch microbeam actuated by fringing electric actuation is investigated in this paper. The arch microbeam is loaded with DC and AC harmonic electric load and the ground electrodes placed at either side of the beam. The curvature caused imbalance distribution of field lines and results in a resultant force. Euler–Bernoulli beam equation was used in accordance with the shallow beam theory to get the equation of motion. Method of multiple scales (MMS) perturbation technique was used to perturb the beam near the fundamental frequency of the microbeam to study its resonant behavior in the local vicinity of the considered frequency. Different midpoint elevations were investigated to study the effect of curvature on the resonance frequency of the beam. The MMS reveals that a beam with low initial midpoint elevation shows initially a softening behavior for small DC voltage excitation. Then, the beam undergoes a hardening when the DC voltage is increased. Finally, the beam returns back to softening behavior when the DC load is further increased to higher values with a curling in the frequency response graph. When the midpoint elevation is increased, the beam is known to undergo symmetry breaking when the DC load is increased before regaining symmetry at even further higher DC load. The MMS shows that there is softening behavior in the initial region prior to symmetry breaking. The effective nonlinearity even drops further to more negative values making the beam more softened in the region of symmetry breaking. After the beam regains symmetry, the effective nonlinearity experiences a more significant drop now causing the beam to be highly softened in this region of high DC load.

BOUSSINESQ MODELING OF SHIP-WAKES AND THEIR CONTRIBUTION TO COASTAL EROSION IN AN ADAPTIVE MESH REFINEMENT SYSTEM

Heavy ship traffic causes a growing concern with respect to public safety, potential damage of coastal structures, and corresponding environmental impacts. High-speed ship-generated wakes such as solitons, undular bores, and breaking bores behave differently compared to wind waves and have a great potential for damage in vulnerable areas such as low-energy coasts and wetlands. In this study, we are developing a multi-grid model framework for the Fully Nonlinear Boussinesq Wave Model, FUNWAVE-TVD (Shi et al., 2012), for simulating ship-wakes in both the operational scale and refined process scales using full two-way coupling. Physical processes in areas of interest requiring higher model resolution, such as the ship-wake generation region, wave breaking in the near-field, and wave evolution with wave-structure interaction in the nearshore field, will be modeled in refined grids embedded in the operational-scale domain. A dynamically adaptive grid algorithm is implemented in order to track a vessel and calculate the physical processes precisely in the wave generation and breaking region in the vicinity of the vessel. Both pressure source and panel source methods for ship wave generation will be tested in the model framework. A concept of nesting layers based on the hierarchical basis, and an efficient parallelization method in the context of the full domain partition are utilized to allow the model to deal with a large-scale computation efficiently in a High Performance Computing (HPC) system.

Factors controlling spatiotemporal variations in stable nitrogen isotopes of Trachurus japonicus larvae and juveniles in the East China Sea

To clarify the factors that affect spatiotemporal isotopic variations in fishes, we examined stable carbon and nitrogen isotope ratios (δ13C and δ15N) of Japanese jack mackerel Trachurus japonicus larvae and juveniles sampled in the shelf break region of the East China Sea (ECS) in April during six consecutive surveys (2005–2010). The δ13C values in fish tissues were similar between northern and southern ECS, while δ15N values were higher in the southern ECS, probably because of lower nitrogen fixation and the presence of fish with larger body size occupying a higher trophic level. Interannual variations in δ15N of T. japonicus juveniles might be mainly contributed by the variation in the abundance of the main diet such as Oncaeidae copepodites and Corycaeus. The isotopic overlaps between epipelagic T. japonicus larvae and other dominant mesopelagic fish larvae were negligible, suggesting lesser competition for food resources. Knowledge regarding spatiotemporal variation in stable isotope ratios of T. japonicus can be applied to understand the feeding habits and migrations of fishes in the ECS.

Gamma-H2AX immunofluorescence for the detection of tissue-specific genotoxicity in vivo.

The phosphorylation of histone H2AX in Serine 139 (gamma-H2AX) marks regions of DNA double strand breaks and contributes to the recruitment of DNA repair factors to the site of DNA damage. Gamma-H2AX is used widely as DNA damage marker in vitro, but its use for genotoxicity assessment in vivo has not been extensively investigated. Here, we developed an image analysis system for the precise quantification of the gamma-H2AX signal, which we used to monitor DNA damage in animals treated with known genotoxicants (EMS, ENU and doxorubicin). To compare this new assay to a validated standard procedure for DNA damage quantification, tissues from the same animals were also analyzed in the comet assay. An increase in the levels of gamma-H2AX was observed in most of the tissues from animals treated with doxorubicin and ENU. Interestingly, the lesions induced by doxorubicin were not easily detected by the standard comet assay, while they were clearly identified by gamma-H2AX staining. Conversely, EMS appeared strongly positive in the comet assay but only mildly in the gamma-H2AX immunofluorescence. These observations suggest that the two methods could complement each other for DNA damage analysis, where gamma-H2AX staining allows the detection of tissue-specific effects in situ. Moreover, since gamma-H2AX staining can be performed on formalin-fixed and paraffin-embedded tissue sections generated during repeated-dose toxicity studies, it does not require any further treatments or extra procedures during dissection, thus optimizing the use of resources and animals. Environ. Mol. Mutagen. 60:4-16, 2019. © 2018 Wiley Periodicals, Inc.

The Circulation Response to Resolved Versus Parametrized Orographic Drag Over Complex Mountain Terrains

AbstractThe accuracy with which parametrizations of orographic blocking and orographic gravity wave drag (OGWD) are able to reproduce the explicitly resolved impacts on flow over complex terrain is investigated in two models: the Met Office Unified Model (MetUM) and the European Centre for Medium‐Range Weather Forecasts Integrated Forecasting System (ECMWF IFS). To this end, global and limited area short‐range forecast experiments across a range of horizontal resolutions, and their model errors relative to analyses, are assessed over two complex mountainous regions: the Himalayas and the Middle East. The impact of resolved orography on the circulation is deduced by taking the difference between high‐resolution experiments with a high (4 to 9 km) and low‐resolution (125 to 150 km) orography. This is then compared with the impact of parametrized orographic drag, deduced from global low‐resolution experiments with and without parametrized orographic drag. At resolutions ranging from tens to hundreds of kilometres, both the MetUM and ECMWF IFS exhibit too strong zonal winds relative to analyses in the lower stratosphere in the region of maximum resolved orographic gravity wave breaking, indicative of some deficiency in the parametrization of OGWD. Diagnosis of the parametrized physics and resolved dynamics tendencies across a range of OGWD parameter values reveal that this error is partly due to the manner in which the resolved dynamics interacts with the parametrized OGWD. This work introduces a method for quantifying the impacts of resolved versus parametrized orographic drag in models and highlights the importance of physics‐dynamics interactions.

Measured acoustic intensity fluctuations on the Chukchi continental shelf during Canada Basin Acoustic Propagation Experiment 2017

One of the main objectives of the Shallow Water (SW) CANAPE experiment was to gain a thorough understanding of a yearlong propagation of broadband signals from deep to shallow water with simultaneous oceanographic and acoustic measurements together along the and across the shelf break region. Using more than eleven acoustic arrays and seven oceanographic moorings in a 30 km2 region on the Chukchi shelf this task is being done by assessing both deep water sound signatures and shallow water source transmissions. In this paper with present analysis of acoustic signals from both shallow and deep water sources on the Chukchi continental shelf for a specific time period between June and August 2017 where a 20 dB intensity drop from along-the-shelf source (S2) at 150 m water depth was observed for more than few weeks. This intensity drop is strongly correlated with occurrence of a large oceanographic event spanning the top 150 m water column due to Pacific Water outflow from Bering sea and retreat of Marginal Ice Zone (MIZ). During the same period, cross-the-shelf source (S1) was not transmitting signal but the reception from the deep water acoustic transmitters also show variability that could be correlated with the basin scale water column variability and the ice coverage. [Work supported by ONR.]

Overview of one year acoustical oceanography measurements on Chukchi shelf during Shallow Water Canada Basin Acoustic Propagation Experiment 2016–2017

A multi-institutional, acoustical oceanography experiment was conducted from October 2016 through November 2017 on the Chukchi continental shelf covering 100–700 m isobaths. Parallel to a deep-water experiment conducted during the same period, the Shallow Water Canada Basin Acoustic Propagation Experiment (SW CANAPE) was designed to assess basin scale acoustic signals on the shelf region while detailed oceanographic dynamic of the shelf break region, particularly the upwelling and other dynamic of the upper 500 m water column, was measured simultaneously. Multiple arrays of oceanographic sensors including upward looking ice profiler, current profiler, temperature, conductivity, and pressure profiles measured temporal and spatial dynamics of 500 m upper ocean in connection with acoustic measurements. Distributed in a 30 km2 area north of Barrow Alaska, vertical line arrays including an L-shaped array, covered upper 200 m of the water column. Two acoustic sources placed at 148 m and 193 m depths on the shelf emitted broadband acoustic signals in frequency bands (700–1100 Hz, and 1400–4000 Hz) along and across the shelf while the sound speed and current profile and surface ice were being measured continuously. Deep water low frequency signals were also recorded. This talk provides an overview of the SW CANAPE experiment and highlights some of the detailed measurements. [Work supported by ONR.]A multi-institutional, acoustical oceanography experiment was conducted from October 2016 through November 2017 on the Chukchi continental shelf covering 100–700 m isobaths. Parallel to a deep-water experiment conducted during the same period, the Shallow Water Canada Basin Acoustic Propagation Experiment (SW CANAPE) was designed to assess basin scale acoustic signals on the shelf region while detailed oceanographic dynamic of the shelf break region, particularly the upwelling and other dynamic of the upper 500 m water column, was measured simultaneously. Multiple arrays of oceanographic sensors including upward looking ice profiler, current profiler, temperature, conductivity, and pressure profiles measured temporal and spatial dynamics of 500 m upper ocean in connection with acoustic measurements. Distributed in a 30 km2 area north of Barrow Alaska, vertical line arrays including an L-shaped array, covered upper 200 m of the water column. Two acoustic sources placed at 148 m and 193 m depths on the shel...

Density Gradient Strategy for Preparation of Broken In2O3 Microtubes with Remarkably Selective Detection of Triethylamine Vapor.

Tubule-like structured metal oxides, combined with macroscale pores onto their surfaces, can fast facilitate gas-accessible diffusion into the sensing channels, thus leading a promoted utilization ratio of sensing layers. However, it generally remains a challenge for developing a reliable approach to prepare them. Herein, this contribution describes a density gradient strategy for obtaining broken In2O3 microtubes from the In2O3 products prepared using a chemical conversion method. These In2O3 microtubes hold a diameter about 1.5 μm with many broken regions and massive ultrafine nanopores onto their surfaces. When employed as a sensing element for detection of triethylamine (TEA) vapor, these broken In2O3 microtubes exhibited a significant response toward TEA at 1-100 ppm and the lowest detected concentration can reach 0.1 ppm. In addition, an excellent selectivity of the sensor to TEA was also displayed, though upon exposure of other interfering vapors, including ammonia, methanol, ethanol, isopropanol, acetone, toluene, and hydrogen. Such promoted sensing performances toward TEA were ascribed to the broken configuration (superior gas permeability and high utilization ratio), one-dimensional configuration with less agglomerations, and low bond energy for C-N in a TEA molecule.

Low-Frequency Dynamics of Strongly Correlated Electrons in (BEDT-TTF)2X Studied by Fluctuation Spectroscopy

Fluctuation spectroscopy measurements of quasi-two-dimensional organic charge-transfer salts (BEDT-TTF) 2 X are reviewed. In the past decade, the method has served as a new approach for studying the low-frequency dynamics of strongly correlated charge carriers in these materials. We review some basic aspects of electronic fluctuations in solids, and give an overview of selected problems where the analysis of 1 / f -type fluctuations and the corresponding slow dynamics provide a better understanding of the underlying physics. These examples are related to (1) an inhomogeneous current distribution due to phase separation and/or a percolative transition; (2) slow dynamics due to a glassy freezing either of structural degrees of freedom coupling to the electronic properties or (3) of the electrons themselves, e.g., when residing on a highly-frustrated crystal lattice, where slow and heterogeneous dynamics are key experimental properties for the vitrification process of a supercooled charge-liquid. Another example is (4), the near divergence and critical slowing down of charge carrier fluctuations at the finite-temperature critical endpoint of the Mott metal-insulator transition. Here also indications for a glassy freezing and temporal and spatial correlated dynamics are found. Mapping out the region of ergodicity breaking and understanding the influence of disorder on the temporal and spatial correlated fluctuations will be an important realm of future studies, as well as the fluctuation properties deep in the Mott or charge-ordered insulating states providing a connection to relaxor or ordered ferroelectric states studied by dielectric spectroscopy.

Approximate message passing for nonconvex sparse regularization with stability and asymptotic analysis

We analyse a linear regression problem with nonconvex regularization called smoothly clipped absolute deviation (SCAD) under an overcomplete Gaussian basis for Gaussian random data. We propose an approximate message passing (AMP) algorithm considering nonconvex regularization, namely SCAD-AMP, and analytically show that the stability condition corresponds to the de Almeida–Thouless condition in spin glass literature. Through asymptotic analysis, we show the correspondence between the density evolution of SCAD-AMP and the replica symmetric (RS) solution. Numerical experiments confirm that for a sufficiently large system size, SCAD-AMP achieves the optimal performance predicted by the replica method. Through replica analysis, a phase transition between replica symmetric and replica symmetry breaking (RSB) region is found in the parameter space of SCAD. The appearance of the RS region for a nonconvex penalty is a significant advantage that indicates the region of smooth landscape of the optimization problem. Furthermore, we analytically show that the statistical representation performance of the SCAD penalty is better than that of -based methods, and the minimum representation error under RS assumption is obtained at the edge of the RS/RSB phase. The correspondence between the convergence of the existing coordinate descent algorithm and RS/RSB transition is also indicated.