Single-parameter Criterion Research Articles

On the Origin of Quenched but Gas-rich Regions at Kiloparsec Scales in Nearby Galaxies

We use resolved spectroscopy from MaNGA to investigate the significance of both local and global properties of galaxies to the cessation of star formation at kpc scales. Quenched regions are identified from a sample of isolated disk galaxies by a single-parameter criterion D n (4000) - log EW(Hα) >1.6−log2=1.3 , and are divided into gas-rich quenched regions (GRQRs) and gas-poor quenched regions according to the surface density of cold gas (Σgas). Both types of quenched regions tend to be hosted by non-AGN galaxies with relatively high mass (M * ≳ 1010 M ⊙) and red colors (NUV − r ≳ 3), as well as low star formation rate and high central density at fixed mass. They span wide ranges in other properties including structural parameters that are similar to the parent sample, indicating that the conditions responsible for quenching in gas-rich regions are largely independent of the global properties of galaxies. We train random forest classifiers and regressors for predicting quenching in our sample with 15 local/global properties. Σ* is the most important property for quenching, especially for GRQRs. These results strongly indicate the important roles of low-mass hot evolved stars, which are numerous and long-lived in quenched regions and can provide substantial radiation pressure to support the surrounding gas against gravitational collapse. The different feature importance for quenching, as found previously by A. F. L. Bluck et al., is partly due to the different definitions of quenched regions, particularly the different requirements on EW(Hα).

What is an ideal Rapid Response System activation criterion for obstetric critically-ill patients: single parameter criteria vs. modified early obstetric warning system criteria vs. any other else?

What is an ideal Rapid Response System activation criterion for obstetric critically-ill patients: single parameter criteria vs. modified early obstetric warning system criteria vs. any other else?

Combining Washout and Noncontrast Data From Adrenal Protocol CT: Improving Diagnostic Performance

To determine if combination of washout and noncontrast data from delayed adrenal computed tomography (CT) improves diagnostic performance, and demonstration of an optimizing analytical framework. This retrospective study consisted of 97 adrenal lesions, in 96 patients, with pathologically proven adrenal lesions (75 benign; 22 malignant), who had undergone noncontrast, portal- and approximate 15-minute delayed-phase CT. Lesion CT attenuations (Hounsfield units [HU]) during each phase, and "absolute" and "relative" percent enhancement washouts (APEW and RPEW) were assessed. The optimum combination of sequential parameters and thresholds was determined by recursive partitioning analysis; resultant diagnostic performance was compared to commonly applied single-parameter criteria for malignancy (noncontrast > 10 HU, APEW < 60%, RPEW < 40%). The above single-parameter criteria yielded sensitivities, specificities, and accuracies for malignancy of 100.0%, 41.3%, and 54.6%; 97.9%, 61.3%, and 69.1%; and 96.6%, 74.7%, and 78.4%, respectively. Recursive partitioning analysis identified noncontrast ≥24.75 HU, with subsequent APEW ≤63.49%, as the optimum sequential parameter-threshold combination, which yielded increased sensitivity, specificity, and accuracy of 100.0%, 85.3%, and 90.7%, respectively. Discrimination using the combined sequential classifier yielded statistically significant improvements in accuracy when compared to the above conventional single-parameter criteria (all P ≤ .039). Sequential application of noncontrast and washout criteria from delayed contrast-enhanced adrenal CT can improve diagnostic performance beyond that of commonly applied single-parameter criteria. Validation of the sequential ordering and refinement of the specific threshold values warrant further study.

A Generalized Johnson Parameter for Pull-Off Decay in the Adhesion of Rough Surfaces

There is no simple theory at present to predict accurately the decay of pull-off in the adhesion of randomly rough surfaces. The asperity model of Fuller and Tabor has shown significant error in recent numerical investigations by Pastewka and Robbins of self-affine random roughness from micrometer to atomic scale which corresponds to low values of Tabor parameter. For sinusoidal contact, the Johnson parameter, originally introduced for the JKR regime (from Johnson-Kendall-Roberts) is the dominant parameter ruling the pull-off at intermediate Tabor values. Hence, we define a generalized Johnson parameter as the ratio between the adhesive energy to the elastic strain energy to flatten the surface in the case of multiscale roughness and find that it correlates very well with the data of Pastewka and Robbins spanning almost five orders of magnitude of reduction from theoretical strength, improving significantly with respect to other possible single parameter criteria. For the most important case in practice, that of low fractal dimensions, this suggests the product of amplitude and slope of the largest wavelength components of roughness dominate pull-off decay, and not small scales features like slopes and curvatures, as suggested by Pastewka and Robbins.

Tension strain failure criterion for concrete

Modelling the ductile performance of concrete structures, particularly for fail-safe and earthquake situations, is still unsatisfactory owing to a cumbersome description of material behaviour. This paper reviews the development of concrete failure criteria and, arising from the distinction between the stress–strain relations measured in tests and ‘independent' material performance, identifies the previously suggested criterion of limiting tensile strain as the most promising for behaviour prediction especially in finite-element exercises. The full description of this single-parameter criterion in the three-dimensional space of principal stress is provided. Its use conveniently avoids the numerical difficulties involved in the hypoelastic material behaviour modelling of current practice and its validity becomes very clear when used to interpret the results of previous experimental work and when compared with other theories.

Effects of slurry pre-treatment and application technique on short-term N 2O emissions as determined by a new non-linear approach

Direct injection of slurry is increasingly used to mitigate odour and ammonia emissions, but this may be at the expense of higher denitrification and N 2O emission rates. This study investigated how injection technique and slurry pre-treatment influence distribution and turnover of slurry nitrogen, and losses via N 2O. Two field experiments were carried out on a loamy sand. Pig slurry was applied to established crops, i.e., to spring barley ( Hordeum vulgare L.) in May 2007, and to winter wheat ( Triticum aestivum L.) in April 2008. In 2007 the slurry was applied by direct injection using either winged or straight tines. In 2008, three slurry types (digested, separated or untreated) were applied by straight tine injection. In both years band spreading of the slurries by trail-hose application was included as reference. Nitrous oxide emissions were quantified using static chambers for up to 44 days after slurry application. A new flux calculation method (HMR) was applied. With HMR, flux estimation is based on non-linear regression using a single-parameter criterion. In connection with gas samplings, soil cores were collected to 20-cm depth within and between bands for analysis of mineral N. Short-term emissions of N 2O corresponded to 0.3–1.5% of the N applied in 2007, and to 0.3–0.7% in 2008. In 2007 N 2O emissions were higher with injection than with surface application of slurry, while there was no consistent difference between the two injection techniques. In 2008 there was no effect of application method, and N 2O emissions from untreated, digested and separated slurry were similar, although higher N 2O emissions from treated slurry were indicated. A conceptual model to explain the observed patterns of N 2O is discussed. Accounting for the indirect emissions of N 2O associated with NH 3 volatilization, production of synthetic fertilizer N and energy used for slurry injection, the overall greenhouse gas emissions associated with trail-hose application, winged tine injection and straight tine injection of slurry corresponded to 830, 997 and 1482 kg CO 2 eq ha −1, respectively. Provided plant damage can be minimized, this moderate increase in greenhouse gas emissions compared to surface application appears to be an acceptable trade-off for the reduction in NH 3 losses achievable with direct injection of slurry to established crops.

Prediction of Chemical Anisotropy on Sidewall of Boron Nitride Nanotubes: A New Application of Directional Curvature Theory

The bond curvature (K), derived from the Directional-Curvature Theory, is developed as a simple and efficient criterion for structures and chemical anisotropy of sidewall [2+1] cycloadditions on single-walled boron nitride nanotubes (SWBNNTs). The origin of the relationship between the chemical anisotropy of SWBNNTs and the bond curvature is explained based on the viewpoint of hybrid orbital theory. The first-principle calculations for the additions on various types of the SWBNNTs show that not those single-parameter criteria, but the K, in which the two parameters R and θ are involved, can solely determine the structure types of the cycloadditions on the B−N bonds and predict the chemical anisotropy of the SWBNNTs. The larger the K is, the more easily the B−N bond is broken, and the binding energies of the opened structures change linearly with K. For the cycloaddition on SWBNNTs with moderate diameter, the boundary of K for determining whether the B−N bond is broken or not is about 1.45 nm−1.

Experimental analysis of irregularities of metallic surfaces generated by abrasive waterjet

Experimental study of the surface quality produced by abrasive waterjet (AWJ) on metallic materials has been performed. The surface roughness/waviness was quantitatively evaluated by using the contactless optical measurement. In order to characterize the cut surface qualities, a single-parameter criterion has been proposed. Based on root mean square (RMS) roughness evaluation of the worst cut surface zone, the dimensionless statistical parameter C can be calculated as a basic quantity for AWJ surface cut characterization. As it was approved, besides its dependency on depth of AWJ trace, the value of C-parameter for the specific material is noticeably related also to the traverse speed of the cutting head. Such a relationship can be potentially used for adjusting the cutting speed of the machining process.

A quasi-invariant single-parameter criterion for linear two-port unconditional stability

This letter presents a novel unconditional stability criterion for linear two-port networks. The criterion involves a new symmetrical single-parameter defined as. It is shown that K/sub t/>1 if and only if a two-port network is unconditionally stable. Moreover, K/sub t/ is invariant under arbitrary lossless termination and reactive matching at either port when unconditional stability exists. Such invariant property is retained so long as |/spl Delta/|/spl les/1, which occurs more frequently than |/spl Delta/|>1 for most devices. The parameter can also be aptly related to the maximum available gain of an unconditionally stable device.

Rollett-based single-parameter criteria for unconditional stability of linear two-ports

A family of linear two-port unconditional stability criteria is presented, which is specified in terms of a single necessary and sufficient condition involving a single parameters. Based on the commonly employed Rollett dual conditions, the stability parameters are derived in a simple and direct manner. The family is extended to include the single-parameters deduced from the dual Rollett and generalised auxiliary conditions. Straightforward proof of the new single-parameter condition implying μ1&gt;1 and vice versa is demonstrated. A comparison of the various criteria and μ′s is also illustrated and discussed. Three members of the single-parameter family are highlighted for being more advantageous than μ1 in different aspects.

J-A2 Characterization of Crack-Tip Fields: Extent of J-A2 Dominance and Size Requirements

The requirements for J-dominance, limits of the single-parameter criterion to characterize the fracture of engineering structures, and two-parameter fracture analyses are first reviewed. Through comparison, it is argued that the two-parameter fracture methodology based on the J-A 2 theory is a reasonable extension of the single parameter (J-integral) fracture methodology. Consequently the extent of J-A 2 dominance in various specimens under either tension or bending is investigated in detail in this paper. Using the J 2 flow theory of plasticity and within the small-strain framework, full field finite element solutions are obtained for both deep and shallow crack geometries of single edge notch bar under pure bending [SEN(B)] and central cracked panel in uniform tension [CC(T)]. These crack-tip stresses are compared with those in the HRR singularity fields and the J-A 2 asymptotic fields at the same level of applied J. The comparison indicates that the size R of the region dominated by the J-A 2 field is much larger than that of the HRR field around the crack tip. Except for deeply-cracked SEN(B) in low hardening material (n=10) under fully plastic conditions, the numerical results near the crack tip in both SEN(B) and CC(T) match very well with the J-A 2 asymptotic solutions in the area of interest 1<r/(J/σ0)<5 from well-contained to large scale plasticity. The implications of these results on the minimal specimen size requirements essential to a two-parameter fracture criterion based on the J-A 2 asymptotic solution are then discussed.

Effect of void growth and shape on the initiation of ductile failure of steels

Notched tensile bars of a high strength structural steel were loaded to first void coalescence. The results show that damage curves determined by using proportionally loaded specimens are not valid for specimens under non-proportional loading. The results of the experiments with different load histories of notched tensile bars show, that a single parameter criterion like reaching a critical void volume is not sufficient to describe the initiation process of void coalescence. The stress-triaxiality at initiation and the shape of the voids exhibit a strong influence on the initiation values. Two ways to describe initiation are shown: A simple one considers a critical combination of void volume, stress-triaxiality and plastic strain at initiation. The other one uses a shape factor to describe the shape of the voids and calculates the initiation values. Both models work with an accuracy in the order of the experimental scatter.

Influence of Strain History on Ductile Failure of Steel

Notched tensile bars of a high strength structural steel were loaded to void coalescense. The results show that the damage curve determined using radially loaded specimens is not valid for specimens under non-radial loading. The results of the experiments with different load histories of notched tensile bars show, that a single parameter criterion like a damage parameter is not sufficient to describe the initiation process of void coalescense. The shape of the voids and the triaxiality at initiation exhibit a strong influence on the initation values. There are two ways to describe the initiation. A simple one considers a critical combination of void growth rate, triaxiality and plastic strain at initiation. The other one uses a shape factor to describe the shape of the voids and calculates the initiation values. Both models work with an accuracy in the order of the experimental scatter.