Narrow Cut Research Articles

MRF-Based Intensity Invariant Elastic Registration of Cardiac Perfusion Images Using Saliency Information

In this paper, we propose a Markov random field-based method that uses saliency and gradient information for elastic registration of dynamic contrast enhanced (DCE) magnetic resonance (MR) images of the heart. DCE-MR images are characterized by rapid intensity changes over time, thus posing challenges for conventional intensity-based registration methods. Saliency information contributes to a contrast invariant metric to identify similar regions in spite of contrast enhancement. Its robustness and accuracy are attributed to a close adherence to a neurobiological model of the human visual system (HVS). The HVS has a remarkable ability to match images in the face of intensity changes and noise. This ability motivated us to explore the efficacy of such a model for registering DCE-MR images. The data penalty is a combination of saliency and gradient information. The smoothness cost depends upon the relative displacement and saliency difference of neighboring pixels. Saliency is also used in a modified narrow band graph cut framework to identify relevant pixels for registration, thus reducing the number of graph nodes and computation time. Experimental results on real patient images demonstrate superior registration accuracy for a combination of saliency and gradient information over other similarity metrics.

Extraction of benzene from a narrow cut of naphtha via liquid-liquid extraction using pure-sulfolane and 2-propanol-sulfolane-mixed solvents

The extraction of benzene from a narrow cut of naphtha produced by the Iranian petrochemical company has been studied at the operating temperatures of 40, 45 and 50 o C, and four solvent-to-feed ratios (S/F) varied over the range of 1-4. Two extraction solvents, sulfolane as a pure-solvent and (sulfolane containing 7 wt% 2-propanol) as a mixed-solvent have been investigated for selective removal of benzene from the naphtha cut. The experimental results demonstrated that the mixed-solvent at 40 o C is a suitable solvent to replace sulfolane for an industrial extraction process for the separation of benzene from the naphtha cut because of its lower price and energy savings.

Inert gas cutting of thick-section stainless steel and medium-section aluminum using a high power fiber laser

Inert gas assisted laser cutting of 10 mm stainless steel plate and 4 mm aluminum sheet was performed with a 5 kW fiber laser. The effects of laser power, cutting speed, focal point position, and assist gas pressure on the cutting performance and cut quality were investigated. Clean cut surfaces without or with minimal dross were achieved with some combinations of process parameters and attempts were made to define parameter windows in terms of cutting speed and laser power for good quality cutting. The maximum cutting speeds for acceptable cut quality were determined at different power levels. The range at which complete through cutting could be achieved (so-called parameter window) was limited upwards by insufficient power intensity to obtain through cutting at high cutting speeds and downwards by heat conduction at slow cutting speeds. The effects of focal point position and assist gas pressure on the striation pattern (cut surface roughness) were also examined. Low surface roughness was achieved with the focal point position inside the workpiece showing the need for a wider kerf for better melt ejection in thick-section metal cutting. There was also a reduction in surface roughness with increase in assist gas pressure, but there was no significant reduction in surface roughness above the gas pressure of 16 bar, which could be due to the gas flow dynamics inside the narrow cut kerf at high assist-gas pressures.

Selective Homogeneous Oxidation System for Producing Hydroperoxides Concentrate: Kinetics of Catalytic Oxidation of Gas Oils

A selective and mild (55 °C and 50 psig) homogeneous oxidation system has been described to produce hydroperoxides from a narrow cut made from typical gas oil. During this process oil, dissolved in wet acetic acid, is treated with air in the presence of the redox couple Co(III)/Co(II) (partially oxidized catalyst, POC). A straightforward route to POC consists of oxidizing Co(II) in wet acetic acid with calculated aqueous potassium chlorate. Initiation is the manifestation of the potent oxidizing ability of Co(III) toward generating alkyl radicals from hydrocarbons in the oil. Classical propagation then leads to assorted hydroperoxides, simultaneously decomposed by POC. Kinetics of the simultaneous formation and decomposition of hydroperoxides, under varying sets of process and composition variables, was studied in an isothermal, mechanically agitated, semibatch reactor, operating in the pure kinetic regime. A unique kinetic model, based on a rare irreversible consecutive reaction network (pseudo-first-ord...

Cloud condensation nuclei and ice nucleation activity of hydrophobic and hydrophilic soot particles

Cloud condensation nuclei (CCN) activity and ice nucleation behavior (for temperatures<or=-40 degrees C) of soot aerosols relevant for atmospheric studies were investigated. Soots were chosen to represent a range of physico-chemical properties, from hydrophobic through a range of hydrophilicity, to hygroscopic. These characteristics were achieved through generation by three different combustion sources; three soots from natural gas pyrolysis (original: TS; graphitized: GTS; and oxidized: TOS), soot from a diffusion flame in an oil lamp burning aviation kerosene (TC1), and soot from a turbulent diffusion flame in an aircraft engine combustor (AEC). All of the samples exhibited some heterogeneity in our experiments, which showed evidence of two or more particle sub-types even within a narrow size cut. The heterogeneity could have resulted from both chemical and sizing differences, the latter attributable in part to particle non-sphericity. Neither GTS nor TS, hydrophobic particles distinguished only by the lower porosity and polarity of the GTS surface, showed CCN activity at or below water supersaturations required for wettable, insoluble particles (the Kelvin limit). TC1 soot particles, despite classification as hydrophilic, did not show CCN activity at or below the Kelvin limit. We attribute this result to the microporosity of this soot. In contrast, oxidized, non-porous, and hydrophilic TOS particles exhibited CCN activation at very near the Kelvin limit, with a small percentage of these particles CCN-active even at lower supersaturations. Due to containing a range of surface coverage of organic and inorganic hydrophilic and hygroscopic compounds, up to approximately 35% of hygroscopic AEC particles were active as CCN, with a small percentage of these particles CCN-active at lower supersaturations. In ice nucleation experiments below -40 degrees C, AEC particles nucleated ice near the expected condition for homogeneous freezing of water from aqueous solutions. In contrast, GTS, TS, and TC1 required relative humidity well in excess of water saturation at -40 degrees C for ice formation. GTS particles required water supersaturation conditions for ice activation even at -51 degrees C. At -51 to -57 degrees C, ice formation in particles with electrical mobility diameter of 200 nm occurred in up to 1 in 1000 TS and TC1 particles, and 1 in 100 TOS particles, at relative humidities below those required for homogeneous freezing in aqueous solutions. Our results suggest that heterogeneous ice nucleation is favored in cirrus conditions on oxidized hydrophilic soot of intermediate polarity. Simple considerations suggest that the impact of hydrophilic soot particles on cirrus cloud formation would be most likely in regions of elevated atmospheric soot number concentrations. The ice formation properties of AEC soot are reasonably consistent with present understanding of the conditions required for aircraft contrail formation and the proportion of soot expected to nucleate under such conditions.

A technique to improve crystal channeling efficiency of charged particles

It is shown that a narrow plane cut near the crystal surfaceconsiderably increases the probability of capture into the stablechanneling motion of positively charged particles entering acrystal at angles smaller than a quarter of the criticalchanneling angle with respect to the crystal planes. At smallestincidence angles the capture probability reaches 99 percent. Apair of crystals bent in orthogonal planes and provided with thecuts allows to reach a 99.9 percent efficiency of single-passdeflection of a proton beam with an ultra small divergence.Conditions necessary for efficient single-pass deflection ofprotons from the LHC beam halo are also discussed.

LC-MS-based method for the qualitative and quantitative analysis of complex lipid mixtures

A simple and robust LC-MS-based methodology for the investigation of lipid mixtures is described, and its application to the analysis of human lipoprotein-associated lipids is demonstrated. After an optional initial fractionation on Silica 60, normal-phase HPLC-MS on a YMC PVA-Sil column is used first for class separation, followed by reversed-phase LC-MS or LC-tandem mass spectrometry using an Atlantis dC18 capillary column, and/or nanospray MS, to fully characterize the individual lipids. The methodology is applied here for the analysis of human apolipoprotein B-associated lipids. This approach allows for the determination of even low percentages of lipids of each molecular species and showed clear differences between lipids associated with apolipoprotein B-100-LDL isolated from a normal individual and those associated with a truncated version, apolipoprotein B-67-containing lipoproteins, isolated from a homozygote patient with familial hypobetalipoproteinemia. The methods described should be easily adaptable to most modern MS instrumentation.

Planar S–F–S Josephson junctions made by focused ion beam etching

Superconductor–ferromagnet–superconductor (S–F–S) Josephson junctions were fabricated by making a narrow cut through a S–F double layer using direct writing by focused ion beam (FIB). Due to a high resolution (spot size smaller than 10 nm) of FIB, junctions with a small separation between superconducting electrodes (⩽30 nm) can be made. Such a short distance is sufficient for achieving a considerable proximity coupling through a diluted CuNi ferromagnet. We have successfully fabricated and studied S–F–S (Nb–CuNi–Nb) and S–S′–S (Nb–Nb/CuNi–Nb) junctions. Junctions exhibit clear Fraunhofer modulation of the critical current as a function of magnetic field, indicating good uniformity of the cut. By changing the depth of the cut, junctions with the I c R n product ranging from 0.5 mV to ∼1 μV were fabricated.

Semi-empirical technique for predicting ash size distribution in CFB boilers

Since coal ash is a large portion of the bed inventory in a coal-fired circulating fluid bed (CFB) boiler furnace, the ash formation data for the feeding coal, i.e., the initial ash size distribution and the fragment and attrition rates, are of significance for predicting the material balance in CFB boiler furnace. A laboratory test procedure for determining the coal characteristics was developed early with ash size distribution data published for six kinds of coal. An analysis of this ash size distribution data showed that the ash particle size distribution from narrow size cut samples of coal has a bimodal nature, with a fine soft component and a coarse hard component both following the Rosin–Rammler (R–R) distribution. This work presents a six-parameter model to simulate the ash size distributions. The cumulative size distribution of ash from coal samples with wide size cuts was well predicted by the model. The cumulative size distribution of the soft ash closely followed the R–R distribution, while the hard ash size distribution resembled the coal samples size distribution with both distributions being similar to a R–R distribution. A semi-empirical technique combined with theoretical analysis was developed to predict the ash size distribution.

Semi-empirical technique for predicting ash size distribution in CFB boilers

Since coal ash is a large portion of the bed inventory in a coal-fired circulating fluid bed (CFB) boiler furnace, the ash formation data for the feeding coal, i.e., the initial ash size distribution and the fragment and attrition rates, are of significance for predicting the material balance in CFB boiler furnace. A laboratory test procedure for determining the coal characteristics was developed early with ash size distribution data published for six kinds of coal. An analysis of this ash size distribution data showed that the ash particle size distribution from narrow size cut samples of coal has a bimodal nature, with a fine soft component and a coarse hard component both following the Rosin–Rammler (R–R) distribution. This work presents a six-parameter model to simulate the ash size distributions. The cumulative size distribution of ash from coal samples with wide size cuts was well predicted by the model. The cumulative size distribution of the soft ash closely followed the R–R distribution, while the hard ash size distribution resembled the coal samples size distribution with both distributions being similar to a R–R distribution. A semi-empirical technique combined with theoretical analysis was developed to predict the ash size distribution.

Statistical and power spectral analysis of quality of fluidization for different particle size distributions at high temperature

Previous studies have shown the effect of many parameters on the operation of a fluidized bed at room temperature, but have not considered the effect of the particle size distribution of bed materials or high temperature. This investigation examines how the high temperature and particle size distributions affect the quality of fluidization. Good quality is regarded as uniformly expressed fluid velocity across through the fluidized bed. Four particle size distributions of silica were fluidized in air at atmospheric pressure, from 500 to 800°C. The evaluated particle size distributions included a narrow cut, a binary mixture, a uniform distribution and a Gaussian distribution. During an experiment, the pressure fluctuations were measured, and then the statistical and power spectrum analyses were performed to assess the quality of fluidization in the fluidized bed. According to the resulting mean amplitude, dominant frequency and fluidization index, the sand bed displays the best quality of fluidization at 1.3 U mf in most cases. When the static bed height is controlled at the shallow bed, the quality of fluidization is highest and the effects of temperature on the four particle distributions are not obvious. Increasing the static bed height causes the influence of temperature to become gradually apparent. The mean amplitude and fluidization index decrease as temperature increases, implying an increase in the quality of fluidization. In all cases, increasing the static bed height causes differences between the four distributions to become gradually apparent. The mean amplitude and index of the narrow distribution are smallest, indicating the fluidization is best. However, the Gaussian distribution shows a similarly narrow behavior. For flat and binary distributions, differently sized components of sand compete in terms of segregation and mixing, affecting the behavior of fluidization, so that both of them belong to the same behavior of fluidization.

Pre-Caving, Drilling and Blasting in the Esmeralda Sector of the El Teniente Mine

El Teniente Mine has developed the method of panel caving as an innovative pre-conditioning caving alternative for traditional mining of sectors located in primary rock. In applying this method, caving speed and area incorporation are the most relevant parameters to establish a desired production level in a specified sector. This is the context in which continuous improvements to several design alternatives have been developed and applied to optimize mine caving. Mine caving, by drilling and blasting, results in a narrow base cut of ore columns not larger than the height of the caving galleries, which usually measure 3.6 m. These confined blasting operations require drilling parallel blastholes that extend from the floor to the roof of the caving gallery. Panel caving aims at mitigating subvertical field stress transmission to the lower levels of the caving gallery. This improves the stability and helps maintain the advancement of the caved zone at the caving level, with respect to the development, preparation and ore mining activities in the production level. This paper analyzes and evaluates different panel caving alternatives. The result is the identification of the most adequate panel caving alternative for conditions in the Esmeralda Mine given safety, technical, operational and economic considerations.

The effect of particle size distribution on minimum fluidization velocity at high temperature

The objective of this research is to study the effect of high temperature and particle size distribution (PSD) on minimum fluidization velocity ( U mf). Four particle size distributions of silica were fluidized in air at atmospheric pressure between 700 and 900 °C. The particle size distributions evaluated included a narrow cut, a binary mixture, a uniform distribution, and a Gaussian distribution, all with similar means. The experimental results revealed a minimum in U mf near 800 °C. The reason might be that interparticle forces would be changed as temperature rose and increased the minimum fluidization velocity. The binary and uniform size distributions behaved similarly to each other but generally had higher U mfs than the Gaussian and narrow cut distributions.

Differential fraction-based kinetic model for simulating hydrodesulfurization process of petroleum fraction

A differential fraction-based kinetic model (DFKM) was proposed to simulate the reaction process in view of the extremely large number of compounds in the petroleum fraction. The results of the simulation experiment on the hydrodesulfurization (HDS) process demonstrated that without considering the exact compounds, DFKM can depict the reaction processes not only of the whole petroleum fraction but of any narrow cut we are interested in. Apparently, this kind of ability, which can be considered as the ‘zoom in/out’ function, is very useful for the further study on the processing techniques of the petroleum fraction. In the meantime, different methods for obtaining the functions needed in DFKM were investigated and satisfactory results were presented.

Structural Features of Large Molecular Mass Material in Coal-Derived Liquids: Catalytic Hydrocracking of the Pyridine-Insoluble Fraction of a Coal-Tar Pitch

The pyridine-insoluble fraction of a coal-tar pitch has been catalytically hydrocracked. The starting sample contained no material that could be observed by gas chromatography/mass spectrometry (GC/MS) or by heated-probe mass spectrometry. The aim of the study was to generate structural information on this narrow cut of large-molecular-mass material, which consisted mainly of compounds boiling above 450°C. A much broader boiling-point distribution was found for hydrocracked products; evidence from all analytical techniques used (size-exclusion chromatography, UV-fluorescence spectroscopy and heated-probe mass spectrometry) indicated a significant reduction of the molecular mass range. A wide variety of aromatic groups was identified in hydrocracked products by heated-probe mass spectrometry, ranging from phenanthrene ( m/z 178) to beyond dibenzocoronene ( m/z 400). Ions corresponding to alkyl ( m/z 43, 57, 71 and 85) and alkenyl groups ( m/z 41, 55, 69 and 83) were detected. The results reflect the ability of the hydrocracking process to cleave bonds within large pitch molecules, releasing the structural units which form the molecules. The structure of the original pyridine-insoluble material may thus be seen as a series of aromatic groups linked by short bridges or small groups, but with some longer aliphatic bridges (C12 and C17) as shown by pyrolysis-GC/MS. Clearly, some molecular species were reduced in mass but still lay above the range of detection by heated-probe mass spectrometry and could not be identified. Although the extent to which large polycyclic aromatic entities themselves have been cracked (or otherwise reduced to smaller polycyclic aromatic groups) cannot be quantitatively discerned from the present data, the hydrocracking of isolated fractions of intractable coal-derived material appears to offer a useful method for probing their structural features.

Influence of the particle size distribution of powders on the velocities of minimum and complete fluidization

This paper presents the results of an experimental study dealing with the influence of the particle size distribution (PSD) on the fluidization regime. It was developed with Geldart B and D-type river sand. Five average diameters were considered between 282.5 and 1800 μm, and four PSD cases were studied for each of them: a reference (narrow cut) powder, a Gaussian-type powder, a binary mixture, and a flat (wide) PSD powder. The Gaussian-type powders fluidize approximately at the same incipient fluidization velocities as the reference powders and therefore the minimum fluidization velocity of a Gaussian-type powder can be estimated by any correlation suitable for uniform-sized powders. On the contrary, flat PSD and binary mixtures have a very different hydrodynamic behavior, although similar to each other. For these mixtures, two characteristic velocities are needed to describe the behavior, i.e. the incipient and complete fluidization velocities. Transition domains between incipient and complete fluidization were also investigated, and the experimental results show they depend to a large extent on the PSD: Gaussian mixtures hardly segregate and they behave like narrow range reference powders, whereas binary and flat PSD mixtures always segregate. It is shown that the transition domain extent is almost independent of the mixture mean diameter and nearly always between 30% and 45%. Experimental results for incipient fluidization and complete fluidization velocities are compared with the minimum fluidization velocity as predicted by several existing correlations for binary mixtures. Most of them are correct for average diameters smaller than 1.5 mm, but only one is satisfactory for larger diameters. Therefore we propose two Re versus Ar correlations for predicting the characteristic velocities that fit our experimental results obtained in a wide average diameter range. It is found experimentally that the complete fluidization velocity is reduced with respect to the minimum fluidization of large particles when the average diameter increases for binary powders. The increasing influence of the small-to-big particles interaction for increasing average diameters may explain this finding. The results of calculations for the gas–particle and particle–particle interactions (i.e. collisions) in the case of the five considered binary powders show clearly that interparticle forces become significant (⩾5%) as soon as the average diameter is larger than 1 mm; this is in total agreement with our experimental results.

Sinophysis canaliculata sp. nov. (Dinophyceae), a new benthic dinoflagellate from western Indian Ocean islands

A new benthic marine dinoflagellate, Sinophysis canaliculata Quod, Ten-Hage, Turquet, Mascarell et Couté sp. nov., was isolated from coral and sediment samples from sites in the western Indian Ocean. This new species is described and illustrated by drawings and light and scanning electron micrographs. Members of Sinophysis Nie et Wang are generally laterally flattened with circular outlines. The new species differ from others of the genus in the following characters: cell shape and size and features of thecal plates (plate shapes, size and number of valve pores, presence of a narrow thecal cut in the left hypothecal plate). Sinophysis canaliculata is heterotrophic, lacking any chloroplasts.

Investigation of Coking Propensity of Narrow Cut Fractions from Athabasca Bitumen Using Hot-Stage Microscopy

The incipient mesophase formation of 10 narrow cut fractions from Athabasca bitumen vacuum bottoms boiling above 525 °C (pitch) derived by supercritical fluid extraction (extraction) using pentane ...

Experimental determination of stress intensity factors due to residual stresses

An experimental method is presented that enables stress intensity factors due to residual stress to be determined directly, without prior determination of the residual stress. The method is based on the crack compliance method, where a narrow cut is introduced progressively into the considered component, and the resulting strain change is measured by a strain gage. The required mathematical relations to determine stress intensity factors from strain measurements are established by means of some basic relations of linear elastic fracture mechanics. They are derived explicitly for two exemplary geometrical systems, which allowed for analytical treatment. Experimental data obtained in the case of a steel roller are presented and discussed.

Somes Sound: Fjord or Well-Mixed Estuary?

Somes Sound has been described as the only example of a fjord on the east coast of the United States. On a small scale, and from a morpho? logical point of view, the Sound has key features normally associated with fjords, including pronounced subaerial topographic relief, submarine sills, and the U-shaped cross-section typical of glacially-carved troughs. However, based on its salinity distribution, which is related to the mixing and circulation processes used to characterize estuarine types from an oceanographic point of view, Somes Sound is a vertically well-mixed estuary that does not exhibit the strong stratification typical of fjords. While its geomorphology is unique, the oceanographic processes operating in the embayment are essentially the same as those in other shallow Maine estuaries with low fresh water input. In these estuaries, as well as in Somes Sound, tidal mixing is dominant over freshwater inflow in determining the circulation and the vertical stratification of the water column. Somes Sound, a narrow cut that nearly divides Mount Desert Island in two (Fig. 1), is morphologically unique among coastal embayments and estuaries along the eastern seaboard of the United States. The coastal embayments of Maine were altered by glacial erosion of the Pleistocene ice sheets and postglacial changes in sea level creating the typical low rolling relief best characterized as a fjard or firth coastline (Belknap et al. 1986; Kjerfve 1989). On the other hand, topographic relief in the Mount Desert region is decidedly more pronounced, and the eastern shore of Somes Sound rises at one point to more than 250 m above sea level. In addition to the spectacular subaerial relief, the submarine topogra? phy of the Sound displays the U-shaped channel cross-section and shallow terminal sill that characterize glacially-carved and deepened valleys. Based on these and other geological characteristics, Johnson (1925) concluded that Somes Sound represents the only possible ex? ception to the statement that the term fjord cannot be properly applied to the coast of Maine. * Department of Oceanography, University of Maine, Orono, ME 04469-5741; ** Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, ME 04575 This content downloaded from 157.55.39.178 on Fri, 05 Aug 2016 04:51:03 UTC All use subject to http://about.jstor.org/terms 36 Northeastern Naturalist Vol. 4, No. 1 Figure 1. Mt. Desert Island