Nominal Depth Research Articles

The Sloan Digital Sky Survey Reverberation Mapping Project: the XMM-Newton X-Ray Source Catalog and Multiband Counterparts

The XMM-RM project was designed to provide X-ray coverage of the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) field. Forty-one XMM-Newton exposures, placed surrounding the Chandra AEGIS field, were taken, covering an area of 6.13 deg2 and reaching a nominal exposure depth of ∼15 ks. We present an X-ray catalog of 3553 sources detected in these data, using a PSF-fitting algorithm and a sample selection threshold that produces a ∼5% fraction of spurious sources. In addition to the PSF-fitting likelihood, we calculate a second source reliability measure based on Poisson theory using source and background counts within an aperture. Using the Poissonian likelihood, we select a subsample with a high purity and find that it has number count profiles similar to previous X-ray surveys. The Bayesian method "NWAY" was employed to identify counterparts of the X-ray sources from the optical Legacy and the IR unWISE catalogs, using a two-dimensional unWISE magnitude–color prior created from optical/IR counterparts of Chandra X-ray sources. A significant number of the optical/IR counterparts correspond to sources with low detection likelihoods, proving the value of retaining the low-likelihood detections in the catalog. A total of 932 of the XMM-RM sources are covered by SDSS spectroscopic observations, where 89% of them are classified as active galactic nuclei, and 71% of these active galactic nuclei are in the SDSS-RM quasar catalog. Among the SDSS-RM quasars, 80% are detectable at the depth of the XMM observations.

Particle Fluxes at the Australian Southern Ocean Time Series (SOTS) Achieve Organic Carbon Sequestration at Rates Close to the Global Median, Are Dominated by Biogenic Carbonates, and Show No Temporal Trends Over 20-Years

Particle fluxes at the Southern Ocean time series (SOTS) site in the Subantarctic zone (SAZ) south of Australia (~47°S, 142°E, 4600m water depth) were collected from 1997 – 2017 using moored sediment traps at nominal depths of 1000m, 2000m and 3800m. Annually integrated mass fluxes showed moderate variability of 14 ± 6 g m-2 yr-1 at 1000m, 20 ± 6 g m-2 yr-1 at 2000m and 21 ± 4 g m-2 yr-1 at 3800m. Particulate organic carbon (POC) fluxes were similar to the global median, indicating that the Subantarctic Southern Ocean exports considerable amounts of carbon to the deep sea despite its high-nutrient, low chlorophyll characteristics. The interannual flux variations were larger than those of net primary productivity as estimated from satellite observations. Particle compositions were dominated by carbonate minerals (> 60% at all depths), opal (~10% at all depths), and particulate organic matter (~17% at 1000m, decreasing to ~10% at 3800m), with seasonal and interannual variability much smaller than for their flux magnitudes. The carbonate counter-pump effect reduced carbon sequestration by ~8±2%. The average seasonal cycle at 1000m had a two-peak structure, with a larger early spring peak (October/November) and a smaller late summer (January/February) peak. At the two deeper traps, these peaks became less distinct with a greater proportion of the fluxes arriving in autumn. Singular value decomposition (SVD) shows that this temperate seasonal structure accounts for ~80% of the total variance (SVD Mode 1), but also that its influence varies significantly relative to Modes 2 and 3 which describe changes in seasonal timings. This occurrence of significant interannual variability in seasonality yet relatively constant annual fluxes, is likely to be useful in selecting appropriate models for the simulation of environmental-ecological coupling and its role in controlling the biological carbon pump. No temporal trends were detected in the mass or component fluxes, or in the time series of the SVD Modes. The SOTS observations provide an important baseline for future changes expected to result from warming, stratification, and acidification in this globally significant region.

The Upper Contact Unit of the Sudbury Igneous Complex in the Garson region: Constraints on the depth of origin of a peak ring at the Sudbury impact structure

AbstractObservational and logical arguments are presented for the lithology formerly named the Garson Member of the Onaping Formation being the clast‐bearing, fine‐grained, chilled Upper Contact Unit (UCU) of the Sudbury Igneous Complex (SIC) in the Garson region of the Sudbury impact structure. It differs considerably, however, from the UCU in the North Range of the SIC with respect to the character of its clasts. Namely, the clasts are essentially monomict (quartzites), much larger (up to 100 m across), and much more abundant (up to 80% in places). These differences indicate a different source than “fallback” material for the clasts in the UCU in the Garson region. Their character requires a “coherent,” singular source that was topographically above the SIC melt pool. Such a source would correspond to that of an emergent peak ring of fractured target rocks. The clasts are identified as Huronian Mississagi quartzite, which is estimated to have been at a nominal depth of 7.5 ± 2.5 km at the time of impact. This provides a constraint on the depth of origin of the peak ring. This depth estimate is closest to the lower depth estimate from current numerical models of Sudbury and the similar‐sized Chicxulub impact structures.

Magnetic penetration depth and Tc in superconducting nickelates

We compute the nominal magnetic penetration depth of $R$NiO$_2$ ($R =$ La, Nd) from first principles calculations and discuss the results in relation to the superconducting $T_c$. We find a marked discrepancy with the well established phenomenology that correlates these two quantities in cuprates (Uemura plot). We also consider the 2D ultrathin limit and estimate the maximum attainable $T_c$ to be $\sim 180$ K according to the Nelson-Kosterliz universal relation between the superfluid density and the transition temperature.

Characterization of a Custom-Made Digital Light Processing Stereolithographic Printer Based on a Slanted Groove Micromixer Geometry

Abstract A custom-made stereolithographic printer using a digital light processing optical (DLP) system based on a digital micromirror device (DMD) was characterized. Several sizes of slanted grooved micromixers (SGM) were produced and typical dimensions were measured and compared to nominal values. The results show that the developed SLA printer is precise enough to be used for prototyping of larger microfluidic devices. The lateral geometries of the smallest printed micromixer designs deviated less than 20 μm from the nominal values and related feature depths deviated for less than 15 μm. However, further modifications are needed in order to improve the repeatability, accuracy, and printing resolution.

Effect of temperature on wear mechanisms of an aluminium - based abradable coating for aircraft engines after a dynamic interaction with a Ti6Al4V blade

Small blade-casing clearances in aircraft engines reduce fuel consumption but increase the risks of contact interactions due to working conditions. These interactions cannot be avoided but their effects can be reduced by using abradable linings thermally sprayed inside the casings. To investigate these interactions and the mechanisms of wear deriving from them, a specific ballistic bench has been developed in order to perform representative tests of the low-pressure compressor environment (up to 270 °C) and enabling only one interaction between an aluminum-based abradable sample and a Ti6Al4V tool. Contact forces and incursion depth were measured for a nominal depth of cut of 100 μm and at a mean velocity of 125 m/s. It has been shown that the temperature affects mainly the abradable behaviour under these high-speed interactions. In addition, the wear that is resulting at high temperature is driven by a process that can be very different from the low temperature case.

Reply: Intraoperative Tissue Perfusion Measurement by Laser Speckle Imaging: A Potential Aid for Reducing Postoperative Complications in Free Flap Breast Reconstruction

Reply: Intraoperative Tissue Perfusion Measurement by Laser Speckle Imaging: A Potential Aid for Reducing Postoperative Complications in Free Flap Breast Reconstruction

Prediction of H α and [O iii] emission line galaxy number counts for future galaxy redshift surveys

ABSTRACT We perform a simulation with Galacticus, a semi-analytical galaxy formation model, to predict the number counts of H α and [O iii] emitting galaxies. With a state-of-the-art N-body simulation, UNIT, we first calibrate Galacticus with the current observation of H α luminosity function. The resulting model coupled with a dust attenuation model, can reproduce the current observations, including the H α luminosity function from HiZELS and number density from WISP. We extrapolate the model prediction to higher redshift and the result is found to be consistent with previous investigations. We then use the same galaxy formation model to predict the number counts for [O iii] emitting galaxies. The result provides further validation of our galaxy formation model and dust model. We present number counts of H α and [O iii] emission line galaxies for three different line flux limits: 5 × 10−17erg s−1 cm−2, 1 × 10−16 erg s−1 cm−2 (6.5σ nominal depth for WFIRST GRS), and 2 × 10−16 erg s−1 cm−2 (3.5σ depth of Euclid GRS). At redshift 2 < z < 3, our model predicts that WFIRST can observe hundreds of [O iii] emission line galaxies per square degree with a line flux limit of 1 × 10−16 erg s−1 cm−2. This will provide accurate measurement of large-scale structure to probe dark energy over a huge cosmic volume to an unprecedented high redshift. Finally, we compare the flux ratio of H α/[O iii] within the redshift range of 0 < z < 3. Our results show the known trend of increasing H α/[O iii] flux ratio with H α flux at low redshift, which becomes a weaker trend at higher redshifts.

Laser-assisted micro-grinding of Si3N4

One of the main challenges in micro-machining of hard to cut materials is the accuracy of the machined part because of high grinding forces which cause tool deflection and rapid tool wear. Non-conventional machining processes have been developed as alternatives to conventional processes for optimizing the machining efficiency and achieving the desired tolerances. This paper addresses a novel Laser-Assisted Micro-Grinding (LAMG) process. For the first time, an ultra-short pulse laser is used to structure micro-grinding tools and a Si3N4 workpiece prior to the micro-grinding. The induced grinding forces and achieved surface roughness as well as the tool deflection and wear by the LAMG process are compared to the Conventional Micro-Grinding (CMG) process. Additionally, the ultra-short pulsed laser ablation process was simulated to find the proper laser parameters corresponding to the desired structure and laser-cut depth. The results proved an enhanced performance of LAMG process in micro-grinding of Si3N4. Using the simulation, the depth of laser cut prior to structuring could be predicted. Structuring, either the workpiece or the tool, significantly reduced the grinding forces. However, a rougher surface resulted via tool structuring. The grinding forces reduced up to almost 40% using 30% structured workpiece surfaces. Structuring the micro-tool (10% structuring) resulted in 60% reduction in the grinding forces with around 40% rougher surface. The accuracy of the part was highly improved by the laser structuring. The actual depth of cut using CMG was 30% lower than the nominal depth of cut. Utilizing LAMG the total nominal depth of cut was removed from material. The comparison between the topography of structured and non-structured tools indicated higher tool wear and shorter tool life with the non-structured tool.

Surface topography analysis in three-dimensional elliptical vibration texturing (3D-EVT)

In this paper, we investigated the microstructured patterns generated on a machined surface during the fabrication of microgrooves using a three-dimensional elliptical vibration (3D-EVT) method. The microstructures in the form of vibration marks were produced as an effect of the overlapping of the elliptical motion of the tool tip in three dimensions. A three-dimensional ultrasonic elliptical device (3D-UED) was developed in a previous study to vibrate a 3D elliptical locus at an ultrasonic frequency of approximately 20.4 kHz. In this study, the microstructured patterns were fabricated with a nominal depth of cut of 10 μm using an ultrasonic frequency (fm) of 20.4 kHz and by varying the nominal cutting speed from 600 to 1500 mm/min. The experimental results reveal that the pitch increases with the nominal cutting speed. The effect of the cutting tool edge on the microstructured pattern was also investigated by comparing the machined surfaces fabricated using single crystal diamond (SCD) and polycrystalline diamond (PCD). The microstructured pattern using a SCD tool has a better quality compared with a PCD tool. Furthermore, the elastic recovery theory is introduced to explain the surface roughness observed through simulation. The elastic recovery value has been found to increase as the nominal cutting speed increases. In addition, the 3D-EVT method reduces the surface roughness and the cutting forces during texturing.

Localizing Snapping Shrimp Noise Using a Small-Aperture Array

In warm shallow waters, one can consistently hear the crackling sound due to snapping shrimp. An individual sound or “snap” is highly impulsive. Knowing the source locations of these snaps facilitates the development of some unique passive sensing applications. One common approach in localizing these snaps is to calculate the time difference of arrival (TDoA) of snaps across sensors of an array. For a snap originating from a short distance away, in terms of a few multiples of the array aperture size, the signal from the snap forms a curved wavefront, such that both the direction of arrival (DoA) and the range of the snap can be obtained by studying the TDoA of the wavefront. However, this method is infeasible for long-range 3-D localization due to the need for large-aperture 3-D arrays. Smaller aperture arrays allow estimation of DoA for far-field sounds, but not the range. Since the ocean surface acts like an acoustic mirror that reflects the snaps, we can estimate the range of the snaps by measuring the TDoA between the direct arrivals and their surface reflections, even if the snaps occur in the far-field of the array. Given a set of perfectly associated direct and surface-reflected snaps, we derive a range estimator parameterized by nominal receiver depth and receiver orientation. In practice, we know these parameters only approximately. The problem is further complicated by the fact that snaps are acoustically similar to each other, and so associating a snap with its surface reflection can be difficult. We propose an algorithm that solves the problem of estimation of snap locations, snap associations, and receiver parameters, jointly. We verify the method through numerical simulation and through experimental results.

Effect of axial vibrations on regenerative chatter in robotic milling

The highly flexible structure of industrial robots introduces new challenges to modeling vibrations during robotic milling processes. This paper studies the contribution of the axial vibrations of the milling end-effector to regenerative chatter in robotic milling. While axial vibrations of the tool are usually neglected in standard CNC machines, in industrial robots, they may significantly affect the stability of the process. The numerical case studies in this work show that the modulation of the nominal depth of cut due to axial vibrations may cause nonlinearities in the cutting forces. In addition, it is also shown that axial vibrations may cause the feed-generated and edge forces to affect the stability of regenerative vibrations in robotic milling.

Ion-irradiation hardening and microstructural evolution in F82H and ferritic alloys

A reduced activation martensitic steel (F82H), Fe−8Cr ferrite model steel (8CrFS) and pure iron (Fe) were irradiated with 6.4 MeV Fe3+ ions at 300 °C to a displacement damage of 30 dpa at a nominal depth of 600 nm. Nano-indentation tests were performed at room temperature in continuous stiffness measurement (CSM) mode before and after the irradiation. Nix-Gao model was used to extract the nano-hardness of specimens and irradiation hardening (ΔH) was measured. Irradiation hardening was observed in all materials with F82H lowest (ΔH = 0.85 GPa) and pure iron highest (ΔH = 4.03 GPa). Transmission electron microscopy (TEM) observations indicated that dislocation loops dominated the damage microstructure after ion-irradiation. Both the average diameter and number density of dislocation loops were obtained. The correlation between microstructure and irradiation hardening was established based on dispersed barrier hardening (DBH) model. The obstacle strength factors of <100> and 1/2 <111> loops were assigned to be 0.54 and 0.17 with an assumption of linear rule.

Candidate massive galaxies atz ∼ 4 in the Dark Energy Survey

Using stellar population models, we predicted that the Dark Energy Survey (DES) - due to its special combination of area (5000 deg. sq.) and depth ($i = 24.3$) - would be in the position to detect massive ($\gtrsim 10^{11}$ M$_{\odot}$) galaxies at $z \sim 4$. We confront those theoretical calculations with the first $\sim 150$ deg. sq. of DES data reaching nominal depth. From a catalogue containing $\sim 5$ million sources, $\sim26000$ were found to have observed-frame $g-r$ vs $r-i$ colours within the locus predicted for $z \sim 4$ massive galaxies. We further removed contamination by stars and artefacts, obtaining 606 galaxies lining up by the model selection box. We obtained their photometric redshifts and physical properties by fitting model templates spanning a wide range of star formation histories, reddening and redshift. Key to constrain the models is the addition, to the optical DES bands $g$, $r$, $i$, $z$, and $Y$, of near-IR $J$, $H$, $K_{s}$ data from the Vista Hemisphere Survey. We further applied several quality cuts to the fitting results, including goodness of fit and a unimodal redshift probability distribution. We finally select 233 candidates whose photometric redshift probability distribution function peaks around $z\sim4$, have high stellar masses ($\log($M$^{*}$/M$_{\odot})\sim 11.7$ for a Salpeter IMF) and ages around 0.1 Gyr, i.e. formation redshift around 5. These properties match those of the progenitors of the most massive galaxies in the local universe. This is an ideal sample for spectroscopic follow-up to select the fraction of galaxies which is truly at high redshift. These initial results and those at the survey completion, which we shall push to higher redshifts, will set unprecedented constraints on galaxy formation, evolution, and the re-ionisation epoch.

The symmetric draining of capillary liquids from containers with interior corners

A new lubrication model solution is found for the late-stage draining of a wetting capillary liquid from a linear interior corner. The solution exploits the symmetry of volumetric sink conditions at opposing ends of such a ‘double-drained’ interior corner flow with applications ranging from liquid recovery in microfluidic devices on Earth to liquid fuel scavenging in large fuel tanks aboard spacecraft. At long times $t$, the nominal liquid depth is $h\sim t^{-1}$, the liquid volume is $V\sim t^{-2}$ and the maximum volumetric liquid removal rate is $Q\sim t^{-3}$. The constraints under which the solution is valid are provided. To qualitatively assess the value of the solution, representative experiments are conducted at larger length scales aboard the International Space Station and at microfluidic length scales in a terrestrial laboratory. Both sets of experiments confirm the predicted power-law dependences. We show that the separation of variables solution offers a method to predict maximum drain rates from related geometries where a single drain location provides the required symmetry of the problem.

A Quantitative Comparison among Different Algorithms for Defects Detection on Aluminum with the Pulsed Thermography Technique

Pulsed thermography is commonly used as a non-destructive technique for evaluating defects within materials and components. In the last few years, many algorithms have been developed with the aim to detect defects and different methods have been used for detecting their size and depth. However, only few works in the literature reported a comparison among the different algorithms in terms of the number of detected defects, the time spent in testing and analysis, and the quantitative evaluation of size and depth. In this work, starting from a pulsed thermographic test carried out on an aluminum specimen with twenty flat bottom holes of known nominal size and depth, different algorithms have been used with the aim to obtain a comparison among them in terms of signal to background contrast (SBC) and number of detected defects by analyzing different time intervals. Moreover, the correlation between SBC and the aspect ratio of the defects has been investigated. The algorithms used have been: Pulsed Phase Thermography (PPT), Slope, Correlation Coefficient (R2), Thermal Signal Reconstruction (TSR) and Principal Component Thermography (PCT). The results showed the advantages, disadvantages, and sensitivity of the various thermographic algorithms.

Distribution of low-molecular lipophilic extractives beneath the surface of air- and kiln-dried Scots pine sapwood boards.

During industrial wood drying, extractives migrate towards the wood surfaces and make the material more susceptible to photo/biodegradation. The present work provides information about the distribution, quantity and nature of lipophilic substances beneath the surface in air- and kiln-dried Scots pine (Pinus sylvestris L.) sapwood boards. Samples were taken from knot-free sapwood surfaces and the composition of lipophilic extractives, phenols and low-molecular fatty/resin acids layers at different nominal depths below the surface was studied gravimetrically, by UV-spectrometry and by gas chromatography-mass spectrometry (GC-MS). The concentration of total extractives was significantly higher in kiln-dried than in air-dried samples and was higher close to the surface than in the layers beneath. The scatter in the values for the lipophilic extractives was high in both drying types, being highest for linoleic acid and slightly lower for palmitic, oleic and stearic acids. The amount of fatty acids was low in kiln-dried boards, probably due to a stronger degradation due to the high temperature employed. The most abundant resin acid was dehydroabietic acid followed by pimaric, isopimaric, and abietic acids in both drying types. It is concluded that during kiln-drying a migration front is created at a depth of 0.25 mm with a thickness of about 0.5 mm.

Ductile-regime machining model for ultrasonic elliptical vibration cutting of brittle materials

Ultrasonic elliptical vibration cutting (UEVC) is attracting much attention in ultra-precision machining of brittle materials as it was found be able to effectively increase the critical depth of cut (dc) of brittle materials. However, the mechanisms for the increased dc are still not fully understood. In this study, a ductile-regime machining model was developed for the UEVC of brittle materials to achieve maximum dc and thus the maximum machining efficiency. It shows that the reasons for the increase of dc are: (1) The actual undeformed chip thickness (UCT) is smaller than the nominal depth of cut (DOC); (2) The distance from transient surface to target surface (DTSTS) can endure the crack propagation within a certain range when UCT exceeds the critical UCT (tc). Based on the ductile-regime machining model, a predictive model was developed for the determination of dc in microgroove plunge-cutting with respect to several determining factors, including DTSTS, UCT, tc and length of the crack (Cm). A series of experiments on plunge-cutting of KDP crystal were conducted. Results showed that the predicted dc match well with the experimental ones. In addition, it was found that dc increases as the amplitude of vibration along the cutting direction increases or the cutting speed decreases, and dc increases first and then decreases as the amplitude of vibration along the thrust direction increases.

The PAU Survey: spectral features and galaxy clustering using simulated narrow-band photometry

We present a mock catalogue for the Physics of the Accelerating Universe Survey (PAUS) and use it to quantify the competitiveness of the narrow band imaging for measuring spectral features and galaxy clustering. The mock agrees with observed number count and redshift distribution data. We demonstrate the importance of including emission lines in the narrow band fluxes. We show that PAUCam has sufficient resolution to measure the strength of the 4000\AA{} break to the nominal PAUS depth. We predict the evolution of a narrow band luminosity function and show how this can be affected by the OII emission line. We introduce new rest frame broad bands (UV and blue) that can be derived directly from the narrow band fluxes. We use these bands along with D4000 and redshift to define galaxy samples and provide predictions for galaxy clustering measurements. We show that systematic errors in the recovery of the projected clustering due to photometric redshift errors in PAUS are significantly smaller than the expected statistical errors. The galaxy clustering on two halo scales can be recovered quantatively without correction, and all qualitative trends seen in the one halo term are recovered. In this analysis mixing between samples reduces the expected contrast between the one halo clustering of red and blue galaxies and demonstrates the importance of a mock catalogue for interpreting galaxy clustering results. The mock catalogue is available on request at https://cosmohub.pic.es/home.

Characterization of ordered dislocation loop raft in Fe3+ irradiated pure iron at 300 °C

Pure iron was irradiated with 6.4 MeV Fe3+ ions at 300 °C to a displacement damage of 30 dpa at a nominal depth of 600 nm. Distinct microstructures were observed at different depth regions by transmission electron microscopy (TEM). In the range of 0–1.2 μm from the irradiation surface, dislocation loops tended to form ordered loop rafts with their habit plane on {100}, while in the range of 1.6–2.3 μm, both line-shaped dislocations and dislocation loops coexisted. Dislocation loops that formed the loop raft had an average size of 3.5 nm with the number density estimated to be 3.6 × 1023 m−3, considering all three variants of the Burgers vectors b = a0<100>. However, the dislocation loops in the range of 1.6–2.3 μm were with Burgers vectors, b = a0/2<111>, and the number density was one order of magnitude lower.