Mismatch Criterion Research Articles

Formation mechanism of composite secondary phase particles in a solution-treated Si-modified Zircaloy-4

Zr-Si binary precipitates affect mechanical and corrosion properties of Si-modified Zircaloy-4. In this study, composite secondary phase precipitates, having a core of C16 Zr2Si precipitate semi-coated with C15 Zr(Fe,Cr)2 Laves phase, were analysed as observed after solution treatment of experimental Si-modified Zircaloy-4. Crystallographic orientation relationship between the body-centred tetragonal (BCT) Zr2Si and face-centred cubic (FCC) Zr(Fe,Cr)2 Laves phase regions was determined to be (101¯)C16 // (110)C15 and [11¯1]C16 // [11¯1]C15. Two regions formed an incoherent interface accommodating about 30 % misfit strain, calculated by Bramfitt two-dimensional lattice mismatch criterion. The mechanism of formation of composite precipitates was described which, in turn, outlines the way for manipulating microstructure of composite precipitates to further optimise mechanical properties of Si-modified Zircaloy-4.

What Is the "Optimal" Target Mismatch Criteria for Acute Ischemic Stroke?

We aimed to compare Perfusion Imaging Mismatch (PIM) and Clinical Core Mismatch (CCM) criteria in ischemic stroke patients to identify the effect of these criteria on selected patient population characteristics and clinical outcomes. Patients from the INternational Stroke Perfusion Imaging REgistry (INSPIRE) who received reperfusion therapy, had pre-treatment multimodal CT, 24-h imaging, and 3 month outcomes were analyzed. Patients were divided into 3 cohorts: endovascular thrombectomy (EVT), intravenous thrombolysis alone with large vessel occlusion (IVT-LVO), and intravenous thrombolysis alone without LVO (IVT-nonLVO). Patients were classified using 6 separate mismatch criteria: PIM-using 3 different measures to define the perfusion deficit (Delay Time, Tmax, or Mean Transit Time); or CCM-mismatch between age-adjusted National Institutes of Health Stroke Scale and CT Perfusion core, defined as relative cerebral blood flow <30% within the perfusion deficit defined in three ways (as above). We assessed the eligibility rate for each mismatch criterion and its ability to identify patients likely to respond to treatment. There were 994 patients eligible for this study. PIM with delay time (PIM-DT) had the highest inclusion rate for both EVT (82.7%) and IVT-LVO (79.5%) cohorts. In PIM positive patients who received EVT, recanalization was strongly associated with achieving an excellent outcome at 90-days (e.g., PIM-DT: mRS 0-1, adjusted OR 4.27, P = 0.005), whereas there was no such association between reperfusion and an excellent outcome with any of the CCM criteria (all p > 0.05). Notably, in IVT-LVO cohort, 58.2% of the PIM-DT positive patients achieved an excellent outcome compared with 31.0% in non-mismatch patients following successful recanalization (P = 0.006).Conclusion: PIM-DT was the optimal mismatch criterion in large vessel occlusion patients, combining a high eligibility rate with better clinical response to reperfusion. No mismatch criterion was useful to identify patients who are most likely response to reperfusion in non-large vessel occlusion patients.

Estimation of Uncertainty of a Volumetric Reservoir Model and Optimization of Numerical Inversion in Well Log Data Interpretation

This study considers an approach to joint inversion of logging data in oil and gas wells for finding the volume fractions of reservoir components. The inversion is reduced to a linear least squares problem with additional iterations to account for physical constraints. To analyse the quality of inversion, uncertainty evaluation tools are developed for both the model responses and inversion results – volume fractions of the reservoir components. The tools include algorithms for construction of depth-related “confidence corridors” for individual properties and standard deviation ellipses to analyse cross-correlations. An optimization problem of improving the quality of inversion by tuning specific readings of logging methods for individual reservoir layers (or facies/lithotypes) is also posed and solved by minimizing a mismatch criterion between the actual and simulated log curves. Thus, the developed toolkit provides a means for optimized joint inversion of logging data with visual control of uncertainty and cross-correlation in the inversion results.

Development of unauthorized airborne emission source identification procedure

The paper presents the procedure for searching sources of unauthorized airborne emissions. To make reasonable regulation decisions on airborne pollutant emissions and to ensure the environmental safety of population, the procedure provides for the determination of a pollutant mass emission value from the source being the cause of high pollution level and the search of a previously unrecognized contamination source in a specified area. To determine the true value of mass emission from the source, the minimum of the mean-root-square mismatch criterion between the computed and measured pollutant concentration in the given location is used.

TEP/tomodensitométrie et imagerie spectroscopique par résonance magnétique tridmensionnelle pour le diagnostic différentiel entre radionécrose cérébrale et rechute tumorale après irradiation en conditions stéréotaxiques de métastases cérébrales : place dans l’arbre décisionnel

PurposeAfter stereotactic radiation therapy for brain metastases, one of the complications is radionecrosis. Differential diagnosis with tumour recurrence can be helped by different methods of imaging, although histology remains the gold standard. According to the treatment centres, practice diverges. The objective of this single-centre retrospective study was to define the power of MRI, PET scan and NMR spectroscopy to establish a decision tree. Material and methodsThis study included patients who underwent stereotactic radiation therapy for brain metastases, and required, during follow-up, both a PET scan and NMR spectroscopy in order to differentiate a radiation necrosis and tumour recurrence. From 2010 to 2015, 25 patients were consistent with these criteria. ResultsConventional MRI technique, with the T1/T2 mismatch criterion, had a specificity of 75% and a sensitivity of only 44%. A lesion quotient greater than 0.3 diagnosed a recurrence with a sensitivity of 92%. PET scan combined the best sensitivity and specificity, respectively of 92% and 69%. Whatever the thresholds used in NMR spectroscopy for choline/N-acetylaspartate and choline/creatin ratios, the power of this imaging modality did not exceed that of PET scan. ConclusionThe criteria described in conventional MRI cannot by themselves establish the differential diagnosis. In first intention in case of doubt, PET scan should be done, combining the best sensitivity and specificity, whereas NMR spectroscopy used in combination does not improve these factors.

Equalization of acoustic source using multi-pole sources and source strength estimation using inverse method

Sound measured at various points around the environment can be evaluated by a series of multi-pole sources and their acoustic strength can be acquired. In this numerical study, a method, called the inverse method, was examined to achieve this goal. A variety of arrangements of different sources were considered and the acoustic strength of these sources was acquired. Through the application of the mismatch criterion, good conformity was observed between these sound models and the original sound. Furthermore, with regard to results, sound was generated via different source arrangements which showed acceptable agreement with the original sound. Finally, an arrangement named ‘sources vertical arrangement’ was selected as the best approach.

Partial oxidation of methane to synthesis gas over NdCaCoO4 catalyst: Kinetic modeling of autothermal reforming

Partial oxidation of methane to synthesis gas using a highly selective catalyst based on NdCaCoO4 has been studied, and rate constants have been determined. To determine the kinetic constants in a thin bed of the catalyst with a mass of 0.1 g, a model of isothermal syngas production process has been implemented and objective functions and computational algorithm to minimize the mismatch criterion between calculated and experimental data have been selected. The oxidative methane reforming process has been modeled in the isothermal and autothermal modes. The calculation results for the isothermal mode have been found to agree with experimental data.

Atomic structure of high-index α2: γm boundaries in a Ti–46.54 at.%Al alloy

Planar, high-index interphase boundaries developed during the α→ γ m transformation in a Ti–46.54% Al alloy were re-examined with a 3-D near-coincidence site analysis. Pairs of low-index planes, fulfilling the Zhang and Purdy [Philos. Magn. A 68 (1993) 279] minimum mismatch criterion, meet along their edges. Atoms at these edges commingle almost linearly, thereby producing a kinetic barrier to boundary migration.

Orientation relationships in precipitation systems

Based on a survey of the literature on orientation relationships in precipitation systems a unified view of all the known relationships in b.c.c./h.c.p. and b.c.c./ f.c.c. systems is presented. Within each set of crystal systems, orientation relationships are closely connected by small fixed rotations whose magnitude depends only on crystal symmetries. Close parallels exist between the two sets of crystal systems, b.c.c./f.c.c. and b.c.c./h.c.p. The regularities observed in the literature survey lead to the hypothesis that precipitate and matrix tend to be related by an invariant line strain. The relative rotation of the two lattices predicted by this hypothesis is determined as a function of the lattice parameter ratio and is consistent with a large number of experimental studies. In the analysis of simple non-coherent precipitate morphologies the criterion of directional mismatch is demonstrated to be superior to the often used planar mismatch criterion. The precipitate morphology sensitively reflects variations in orientation relationships. Morphologies of coherent and equilibrium semicoherent precipitates are governed by more complex criteria but are also dominated mainly by crystallographic requirements.