Neighboring Surface Research Articles

A Watershed Modeling Framework for Phosphorus Loading from Residential and Agricultural Sources

Phosphorus (P) loading from residential onsite wastewater systems (OWSs) into neighboring surface waters is a poorly understood process in rural watersheds; this can be further challenged when rural residential dwellings are intermixed with agricultural land use. The objectives of this research were (i) to design a P onsite wastewater simulator (POWSIM) to assess P loads from individual or clusters of residential OWSs typically used in Nova Scotia, Canada; and (ii) to simulate OWS P loads in a mixed agricultural watershed (Thomas Brook Watershed [TBW], NS) using the Soil and Water Assessment Tool (SWAT) model in conjunction with POWSIM, to predict and compare P loading from agricultural and residential sources. The POWSIM loading tool has three computational components: (i) disposal field selection and treatment media mass calculation, (ii) disposal field P treatment dynamics, and (iii) soil subsurface plume P treatment dynamics. The combination TBW POWSIM and SWAT modeling approach produced a better simulation of baseflow total P (TP) loads in both a predominantly residential subcatchment and one dominated by agriculture than the SWAT model without POWSIM. The residential subcatchment had 48% of its average annual land use TP load (simulated) contributed by OWSs, whereas the agricultural subcatchment had 39%. Watershed-scale sensitivity analyses of POWSIM input parameters for 18- and 50-yr OWS operation periods found the P loading rate into the disposal field, long-term P removal rates in the disposal field and soil systems, soil maximum P sorption capacity, and mass of native soil involved in P treatment to be most sensitive.

Temperature-Dependent Evolution of the Molecular Configuration of Oxo-Tungsten(VI) Species Deposited on the Surface of Titania

The pH and temperature evolution of the molecular configuration of oxo-tungsten(VI) species deposited on TiO2 by equilibrium deposition filtration and the temperature evolution of the samples texture are studied using in situ Raman spectroscopy, DR spectroscopy, N2 adsorption–desorption measurements, and TGA. Prior to drying, WO42– monomers retained above a bridging surface hydroxyl of TiO2 through H bonding (with a Ti2OH···O–WO3 umbrella configuration) prevail at pH = 9. A pH decrease results in a gradual transformation to an inner sphere monosubstituted species located above terminal surface oxygen (Ti–O–WO3). At pH = 7 both species coexist, whereas at pH = 5 the latter prevails with electrostatically retained polyoxotungstes also present. Heating to 100 °C causes the same effect resulted by the pH decrease at room temperature, that is, transformation of Ti2OH···O–WO3 into Ti–O–WO3, attributed to the removal of H2O molecules upon heating, thereby liberating surface Ti atoms. Progressive heating to higher temperatures causes further removal of surface hydroxyls (confirmed also by TGA) liberating more neighbor surface Ti atoms and favoring further anchoring. This leads to formation of bisubstituted dioxo (Ti–O)2–W(═O)2 sites in the range 120–250 °C and to the prevalence of trisubstituted mono-oxo (Ti–O)3-W═O sites at 430 °C. Polyoxotungstates are also detected in the sample with the highest W loading. The DRS spectra indicate a charge transfer effect between the surface O and Ti atoms proceeding via Ti–O–W surface bridges. Calcination of the support causes a decrease of the pore volume and pore area in the range of pores with small width and an increase in the range of pores with large width. This effect is not affected by the presence of the well dispersed “bi-dimensional” W species inferred by the Raman study.

Exemplar-Based Color Constancy and Multiple Illumination.

Exemplar-based learning or, equally, nearest neighbor methods have recently gained interest from researchers in a variety of computer science domains because of the prevalence of large amounts of accessible data and storage capacity. In computer vision, these types of technique have been successful in several problems such as scene recognition, shape matching, image parsing, character recognition, and object detection. Applying the concept of exemplar-based learning to the problem of color constancy seems odd at first glance since, in the first place, similar nearest neighbor images are not usually affected by precisely similar illuminants and, in the second place, gathering a dataset consisting of all possible real-world images, including indoor and outdoor scenes and for all possible illuminant colors and intensities, is indeed impossible. In this paper, we instead focus on surfaces in the image and address the color constancy problem by unsupervised learning of an appropriate model for each training surface in training images. We find nearest neighbor models for each surface in a test image and estimate its illumination based on comparing the statistics of pixels belonging to nearest neighbor surfaces and the target surface. The final illumination estimation results from combining these estimated illuminants over surfaces to generate a unique estimate. We show that it performs very well, for standard datasets, compared to current color constancy algorithms, including when learning based on one image dataset is applied to tests from a different dataset. The proposed method has the advantage of overcoming multi-illuminant situations, which is not possible for most current methods since they assume the color of the illuminant is constant all over the image. We show a technique to overcome the multiple illuminant situation using the proposed method and test our technique on images with two distinct sources of illumination using a multiple-illuminant color constancy dataset. The concept proposed here is a completely new approach to the color constancy problem and provides a simple learning-based framework.

Surface integrity of micro-dent arrays fabricated by a novel laser shock processing on the surface of ANSI 304 stainless steel

In this paper, a novel micro-dent array fabrication technique called net mask laser shock processing (NMLSP) was proposed. Micro-dent arrays were successfully fabricated on the surface of ANSI 304 stainless steel. The research goals of this paper are to find out the influence of processing parameters on the surface topography, microhardness and residual stress distribution of treated samples. A new method was proposed to measure the microhardness of unregularly curved surface. This method can be adapted to measure any type of surface with high precision. Results showed that the surface topography and the microhardness-distribution were different from previous studies. These were because the interference of neighboring surface shock waves. Compressive residual stress was found on the curved surface although the treated region was masked. However, it did not be saturated as regular laser shock processing (LSP) treatment after five NMLSP impacts.

Effect of Manure Application on Abundance of Antibiotic Resistance Genes and Their Attenuation Rates in Soil: Field-Scale Mass Balance Approach

The development of models for understanding antibiotic resistance gene (ARG) persistence and transport is a critical next step toward informing mitigation strategies to prevent the spread of antibiotic resistance in the environment. A field study was performed that used a mass balance approach to gain insight into the transport and dissipation of ARGs following land application of manure. Soil from a small drainage plot including a manure application site, an unmanured control site, and an adjacent stream and buffer zone were sampled for ARGs and metals before and after application of dairy manure slurry and a dry stack mixture of equine, bovine, and ovine manure. Results of mass balance suggest growth of bacterial hosts containing ARGs and/or horizontal gene transfer immediately following slurry application with respect to ermF, sul1, and sul2 and following a lag (13 days) for dry-stack-amended soils. Generally no effects on tet(G), tet(O), or tet(W) soil concentrations were observed despite the presence of these genes in applied manure. Dissipation rates were fastest for ermF in slurry-treated soils (logarithmic decay coefficient of -3.5) and for sul1 and sul2 in dry-stack-amended soils (logarithmic decay coefficients of -0.54 and -0.48, respectively), and evidence for surface and subsurface transport was not observed. Results provide a mass balance approach for tracking ARG fate and insights to inform modeling and limiting the transport of manure-borne ARGs to neighboring surface water.

The (0001)A surface phase diagram

AbstractThe (0001)A surface phase diagram of InxGa1‐xN is investigated by using different approximations of the cluster variation method with the one‐, two‐ and three‐point basic clusters. The surface layer is considered in the total composition range as a binary regular solution on the triangular lattice. The miscibility gap temperature and concentration of the nearest neighbor surface atoms at this temperature are estimated as functions of the composition. The miscibility gap temperatures of In0.5Ga0.5N obtained by one‐, two‐ and three‐point cluster approximations are 710 °C, 535 °C and 370 °C, respectively. The strong InIn and GaGa pair clustering in comparison with InGa pair formation at temperatures higher than the miscibility gap one is demonstrated in the three‐point approximation. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A Molecular Modeling Study of N2 Desorption from NO Heterogeneous Reduction on Char

Mechanisms of N2 desorption from NO heterogeneous reduction on char surface were investigated by molecular modeling using density functional theory. All geometric optimization and single point energy calculations were performed at B3LYP/6-31G(d) level. Adsorption of NO on a char surface was a strongly exothermic process. Two different reaction pathways for N2 desorption were obtained by calculations, both of which released more than 1,000 kJ/mol. The energy barrier of the rate-limiting step for N2 desorption was 95 kJ/mol by reaction of surface carbon-nitrogen species with another NO molecule and was 205 kJ/mol by combination of two neighboring surface carbon-nitrogen species. The forward reaction rate of each intermediate reaction was calculated employing conventional transition state theory. Predicted rate constants of rate-limiting steps were 3.17 × 1011 s−1 and 7.52 × 107 s−1 at 1,400 K for the two foregoing reactions, respectively.

Predictive modeling of self-catalyzed III-V nanowire growth

We develop a quantitative model of the self-catalyzed vapor-liquid-solid growth of GaAs nanowires, that depends on only a few a priori unknown physical parameters. The model is based on the sole consideration of the As species and incorporates all relevant mechanisms of exchange of As between the vapor, liquid, and solid phases, namely direct impingement of molecules on the droplet, their re-emission by the neighboring surfaces, evaporation from the droplet, and nucleation at the solid-liquid interface. It reproduces quantitatively all salient features of our experimental study, namely the variations of nanowire growth rate with As flux, temperature, and nanowire radius. From these optimized fits, we extract a complete set of model parameters, in particular the nucleus edge energy. We also determine quantities so far inaccessible to experiment, such as the As concentration in the droplet (about 1%), supersaturation of the liquid, and nucleation barrier, for individual nanowires. The model can then be used to predict the growth rate (and all quantities of interest) for an arbitrary GaAs nanowire of given geometry in arbitrary growth conditions, including conditions not yet explored experimentally, provided the fraction of the As flux re-emitted by its environment is known. Although largely ignoring group III elements, our model captures most of the physics of self-catalyzed nanowire growth.

Mapped B-spline basis functions for shape design and isogeometric analysis over an arbitrary parameterization

It is well-known that B-spline surfaces are defined by a regular array of control vertices. In case of models with arbitrary topology, it is extremely difficult to maintain continuity conditions among neighboring surfaces. The scenario is also true for applications in isogeometric analysis (IGA). This paper presents a novel method for shape design and isogeometric analysis from a quadrilateral control mesh of arbitrary topology using mapped B-spline basis functions. Based on an arbitrary input quadrilateral control mesh, a global parameterization of the final surface is first defined through a Gravity Center Method (GCM). A re-parameterization method is then applied to map a B-spline basis function to others that are explicitly defined and are tailored to each of the control vertices which can be either regular or extraordinary ones. The final surface is defined by all the input control vertices with their corresponding mapped basis functions. For practical implementation, the surface can be evaluated patch by patch. Depending on the order of the B-spline basis function used for mapping to others, the global continuity of the resulting surface, including at extraordinary points, can be arbitrary higher order. In the present paper, a uniform cubic B-spline basis function is used and the resulting surface is globally C2 continuous. Several numerical examples are provided to demonstrate the proposed method for both shape design and isogeometric analysis.

Galaxy And Mass Assembly: resolving the role of environment in galaxy evolution

We present observations of 18 galaxies from the Galaxy And Mass Assembly (GAMA) survey made with the SPIRAL optical integral field unit (IFU) on the Anglo-Australian Telescope. The galaxies are selected to have a narrow range in stellar mass (6x10^9Msolar < M* <2x10^10 Msolar) in order to focus on the effects of environment. Local galaxy environments are measured quantitatively using 5th nearest neighbour surface densities. We find that the total star formation rates (SFR) measured from the IFU data are consistent with total SFRs measured from aperture correcting either GAMA or Sloan Digital Sky Survey single-fibre observations. The mean differences are SFR_GAMA/SFR_IFU = 1.26+/-0.23, sigma=0.90 and for the Sloan Digital Sky Survey we similarly find SFR_Brinchmann/SFR_IFU = 1.34+/-0.17, sigma=0.67. Examining the relationships with environment, we find off-centre and clumpy Halpha emission is not significantly dependent on environment, being present in 2/7 (29^+20_-11 per cent) galaxies in high-density environments (>0.77 Mpc^-2), and 5/11 (45^+15_-13 per cent) galaxies in low-density environments (<0.77 Mpc^-2). We find a weak but not significant relationship of the total star formation rates of star-forming galaxies with environment. Due to the size of our sample and the scatter observed we do not draw a definitive conclusion about a possible SFR dependence on environment. Examining the spatial distribution of the Halpha emission, we find no evidence for a change in shape or amplitude of the radial profile of star-forming galaxies with environment. If these observations are borne out in larger samples this would infer that any environment-driven star-formation suppression must either act very rapidly (the `infall-and-quench' model) or that galaxies must evolve in a density-dependent manner (an `in-situ evolution' model).

A multilevel model for spatially correlated binary data in the presence of misclassification: an application in oral health research

Dental caries is a highly prevalent disease affecting the tooth's hard tissues by acid-forming bacteria. The past and present caries status of a tooth is characterized by a response called caries experience (CE). Several epidemiological studies have explored risk factors for CE. However, the detection of CE is prone to misclassification because some cases are neither clearly carious nor noncarious, and this needs to be incorporated into the epidemiological models for CE data. From a dentist's point of view, it is most appealing to analyze CE on the tooth's surface, implying that the multilevel structure of the data (surface-tooth-mouth) needs to be taken into account. In addition, CE data are spatially referenced, that is, an active lesion on one surface may impact the decay process of the neighboring surfaces, and that might also influence the process of scoring CE. In this paper, we investigate two hypotheses: that is, (i) CE outcomes recorded at surface level are spatially associated; and (ii) the dental examiners exhibit some spatial behavior while scoring CE at surface level, by using a spatially referenced multilevel autologistic model, corrected for misclassification. These hypotheses were tested on the well-known Signal Tandmobiel® study on dental caries, and simulation studies were conducted to assess the effect of misclassification and strength of spatial dependence on the autologistic model parameters. Our results indicate a substantial spatial dependency in the examiners' scoring behavior and also in the prevalence of CE at surface level.

Local Shape Similarity and Mean-Shift Curvature for Deformable Surface Mapping of Anatomical Structures

This paper reports a novel method for deformable registration of digital anatomical surfaces. The method capitalizes upon the iterative local affine iterative closest point (ICP) approach that applies an affine transformation per surface vertex along with a regularization constraint to force neighboring surface vertices to undergo similar transformations. More robust vertex correspondence with respect to simple closest point was obtained by exploiting local shape similarity metrics, which includes vertex distance, surface normal, and local curvature. The local curvature was mean shifted at run-time, during the iterative optimization, to make the point correspondence process less dependent upon the surface noise and resolution. The experimental validation was performed on three surface datasets (femur, hemi-pelvic bone, and liver). The registration results showed that the proposed method outperforms, across all the three surface datasets (rmse: 0.19 mm, 0.30 mm, 0.61 mm), global affine ICP (rmse: 2.89 mm, 3.95 mm, and 8.30 mm), local affine ICP (rmse: 0.31 mm, 1.61 mm, and 1.63 mm) and coherent point drift (rmse: 1.99 mm, 2.39 mm, and 4.78 mm) methods. As a whole, the mean-shifted curvature increased the registration accuracy by about 20%.

Squeak and rattle noise prediction for trimmed door of a car using hybrid statistical energy—Finite element method analysis

Squeak and rattle (S&R) noise are important in-cabin sources of annoyance for occupants. Originally, S&R is generated as a result of colliding and slamming of car’s trim and body structure, which in turn occurs because of the dynamic displacements of components excited by road and powertrain. Squeak noise is interpreted as periodic stick and slip phenomena in the contact boundary of two neighbor surfaces. While rattle noise is the emitted noise when adjacent surfaces collide and impact. Both squeak and rattle phenomena happen in high-frequency range, even though the excitation sources (road and powertrain line) works in low frequency range. In practice, squeak and rattle noise can be minimized via controlling the gaps through a tolerance analysis, as well as the appropriate choice of materials. In this research, potential S&R sources are investigated for the trimmed door of a car using clearance analysis. Impact statistics and overall force level at potential rattle places are calculated through random vibration excitation analyses and afterwards, acoustic sensitivity, overall acoustic response, and loudness are calculated by the aim of hybrid SEA-FE method. The results of this prediction will be used in noise and vibration control plan of the whole car in design phase.

STM imagery and density functional calculations of C60fullerene adsorption on the 6H-SiC(0001)-3×3 surface

Scanning tunneling microscopy (STM) studies of the fullerene C${}_{60}$ molecule adsorbed on the silicon carbide SiC(0001)-$3\ifmmode\times\else\texttimes\fi{}3$ surface, combined with density functional theory (DFT) calculations, show that chemisorption of individual C${}_{60}$ molecules occurs through the formation of one bond to one silicon adatom only in contrast to multiple bond formation on other semiconducting surfaces. We observe three stable adsorption sites with respect to the Si adatoms of the surface unit cell. Comprehensive DFT calculations give different adsorption energies for the three most abundant sites showing that van der Waals forces between the C${}_{60}$ molecule and the neighboring surface atoms need to be considered. The C${}_{60}$ molecules are observed to form small clusters even at low coverage indicating the presence of a mobile molecular precursor state and nonnegligible intermolecular interactions.

Direct 2H NMR Observation of the Proton Mobility of the Acidic Sites of Anhydrous 12‐Tungstophosphoric Acid

Flip and hop before you're caught! The proton dynamics of solid 12-tungstophosphoric acid (TPA) is probed by solid-state (2)H NMR in a temperature range from 293-503 K. Protons of TPA are shown to be involved in two types of molecular motion (see picture): the anisotropic local two-site flipping between the two possible orientations of the O-H bond at bridged oxygens of the Keggin anion, and the isotropic diffusion by hopping between neighboring surface oxygens of the anion.

Thermal stability of uni-size Pt cluster disk constructed on silicon substrate

Thermal stability of a uni-size platinum cluster disk, Pt30, constructed on a silicon (111) surface was investigated in a temperature range from room temperature to 773 K by means of a scanning tunneling microscope (STM). The apparent height and diameter and the number density of the cluster disks were obtained from the STM images as a function of the heating temperature. According to the statistical analysis of these specific values, it has been concluded that both the cluster disk and the neighboring substrate surface are stable up to 673 K, then they start being decomposed at the higher temperatures.

Laboratory and field dissipation of penoxsulam, tricyclazole and profoxydim in rice paddy systems

Rice cultivation relies on pesticide applications to ensure high yields. However, the regular use of pesticides seriously affects the quality of neighboring surface water systems. Thus complete knowledge of the environmental fate and dissipation of pesticides in the paddy rice environment should become available. So far only a few studies have provided comprehensive assessment of the dissipation of pesticides under the submerged cultivation conditions followed in rice. Thus, laboratory and 2-year field studies were performed to assess the dissipation of two new generation rice herbicides (penoxsulam and profoxydim) and one of the most important rice fungicides (tricyclazole). A good agreement between laboratory and field experiments was observed with a faster dissipation of penoxsulam and tricyclazole under field conditions. Profoxydim was the least persistent chemical (DT50 soil<1d; DT50 water 0.5–1.2d), followed by penoxsulam which persisted for longer particularly in the water compartment (DT50water=3.8–5.9d). Tricyclazole was the most persistent pesticide, especially in the soil compartment with DT50 values of 44.5–84.6 (field) and 197d (laboratory). These results could be utilized for the assessment of the environmental risk associated with the use of those pesticides in rice cultivation and the determination of potential mitigation measures for minimizing the risk for contamination of neighboring natural water resources.

Electronic structures of a Zn vacancy on the ZnO(10 $\bar 1$ 0) surface: Density functional theory calculations

We perform spin-polarized density functional theory calculations for a Zn vacancy on the ZnO(10 $\bar 1$ 0) surface. Two stable configurations of the surface Zn vacancy are found, and the activation energy barrier is estimated to be ∼0.01 eV. The lower energy configuration has a newly formed surface Zn-O bond to restore the bulk-like structure on the surface. Due to the newly formed bond, the vacancy state in the band gap is characterized by a complicated hybridization of neighboring surface and subsurface atoms and by a more extended electron density. Despite such a hybridization, the surface Zn vacancy is found to have a robust magnetic moment of 1 μ B , implying that surface Zn vacancies may be responsible for the ferromagnetism observed in ZnO thin films and nanoparticles. Simulated scanning tunneling microscope images show that the two structures of the surface Zn vacancy can be distinguished in the filled-state images.

Determination of the Cutting Area Considering the Tool Slenderness Ratio for the Development of a 5-Axis Impeller Machining Automation CAM Module

The efficiency of applying 5-axis machining is higher for various products compared to general 3-axis machining, which is restricted to general parts and mold machining. However, impeller machining requires a large tool slenderness ratio to avoid interference with neighboring surfaces. Because such an enlargement of the slenderness ratio causes damage to the tools and deterioration of the quality of products due to the vibration of the tool, it is important to review the cutting characteristics considering the slenderness ratio and to determine the proper cutting conditions. Also, industry has attempted to develop a 5-axis machining automatic CAM module for an impeller that helps inexperienced workers to process the impeller easily by simplifying the process and options for the cutting impeller. The, current status of research on the cutting conditions considering the slenderness ratio to complete a database for a sub-module accounting for the cutting conditions among the components of an automatic CAM module is urgent. Therefore, the purpose of this work is to review the cutting characteristics that influence the cutting of aluminum alloy, the typical material of impeller parts, while also considering slenderness ratio to complete the 5-axis machining automatic CAM module of an impeller and to determine the available cutting area during the roughing and finishing operations.

Planar integrated plasmonic mid-IR spectrometer

ABSTRACTA compact spectrometer-on-a-chip featuring a plasmonic molecular interaction region has been conceived, designed, modeled, and partially fabricated. The silicon-on-insulator (SOI) system is the chosen platform for the integration. The low loss of both silicon and SiO2 between 3 and 4 μm wavelengths enables silicon waveguides on SiO2 as the basis for molecular sensors at these wavelengths. Important characteristic molecular vibrations occur in this range, namely the bond stretching modes C-H (Alkynes), O-H (monomeric alcohols, phenols) and N-H (Amines), as well as CO double bonds, NH2, and CN. The device consists of a broad-band infrared LED, photonic waveguides, photon-to-plasmon transformers, a molecular interaction region, dispersive structures, and detectors. Photonic waveguide modes are adiabatically converted into SPPs on a neighboring metal surface by a tapered waveguide. The plasmonic interaction region enhances optical intensity, which allows a reduction of the overall device size without a reduction of the interaction length, in comparison to ordinary optical methods. After the SPPs propagate through the interaction region, they are converted back into photonic waveguide modes by a second taper. The dispersing region consists of a series of micro-ring resonators with photodetectors coupled to each resonator. Design parameters were optimized via electro-dynamic simulations. Fabrication was performed using a combination of photo- and electron-beam-lithography together with standard silicon processing techniques.