The pulsed electro-co-deposition process was used on mild steel substrate to develop Ni-W based composite coating which comprises of ZrO2 and TiO2 oxide nanoparticles. In the deposition bath, plating ...parameters and ZrO2 content were maintained constant, whereas, TiO2 content was varied. Phase constitution, morphology, and chemistry of the coatings were examined by X-ray diffraction, field emission scanning electron microscopy and energy dispersive spectroscopy respectively. Surface-mechanical properties were evaluated by wear and microhardness test. Potentiodynamic polarization technique and electrochemical impedance spectroscopy were employed to determine the corrosion resistance of the coatings in a 3.5% NaCl solution. In addition, the isothermal oxidation test was conducted on the coatings at different temperatures (600, 700 and 800 °C) to evaluate the oxidation properties. From the experimental results, it got evidenced that microstructure, microhardness, wear, oxidation and corrosion properties of coatings significantly affected by the incorporation of ZrO2 and TiO2 nanoparticles. Under constant ZrO2 content, microhardness, corrosion and wear resistance of the coatings were significantly improved with increasing TiO2 content (0–15 g/L bath). Coatings with TiO2 addition were more beneficial as compared to the Ni-W and Ni-W-ZrO2 coatings. The oxidation resistance of Ni-W coating was improved after the dispersion of ultrafine ZrO2 and TiO2 particles in the matrix. Optimum values of hardness (963 HV0.05), corrosion resistance (Rct: 6082 ± 33 Ω·cm2) and wear resistance were achieved in the case of Ni-W-5 g/L ZrO2-15 g/L TiO2 composite coating.
•TiO2 leads to finer morphology of electrodeposited Ni-W-ZrO2-TiO2 composite coating.•TiO2 incorporation improves surface mechanical, corrosion and oxidation properties.•Ni-W-5 g/LZrO2-15 g/L coating shows highest hardness (963 HV0.01), corrosion resistance.
•Meta-analysed internet-delivered CBT (iCBT)for depression and anxiety disorders.•The mean effect size (g = 0.80, NNT = 2.34) was maintained at follow up after 3–36 months.•Face-to-face CBT, iCBT, ...and bibliotherapy are equally effective.•On average, face-to-face therapy requires 7.8 times more therapist time than iCBT.•iCBT has high rates of satisfaction and acceptability, and moderate adherence.
A 2010 meta-analysis of internet-delivered CBT (iCBT) RCTs argued ‘computer therapy for the anxiety and depressive disorders was effective, acceptable and practical health care’ without data on effectiveness or practicality in routine practice.
Databases, reviews and meta-analyses were searched for randomised controlled trials of cCBT or iCBT versus a control group (care as usual, waitlist, information control, psychological placebo, pill placebo, etc.) in people who met diagnostic criteria for major depression, panic disorder, social anxiety disorder or generalised anxiety disorder. Number randomised, superiority of treatment versus control (Hedges’g) on primary outcome measure, length of follow-up, follow up outcome, patient adherence and satisfaction/harm were extracted; risk of bias was assessed. A search for studies on effectiveness of iCBT in clinical practice was conducted.
64 trials were identified. The mean effect size (efficacy) was g = 0.80 (NNT 2.34), and benefit was evident across all four disorders. Improvement was maintained at follow-with good acceptability. Research probity was good, and bias risk low. In addition, nine studies comparing iCBT with traditional face-to-face CBT and three comparing iCBT with bibliotherapy were identified. All three modes of treatment delivery appeared equally beneficial. The results of effectiveness studies were congruent with the results of the efficacy trials.
Studies variably measured changes in quality of life and disability, and the lack of comparisons with medications weakens the field.
The conclusions drawn in the original meta-analysis are now supported: iCBT for the anxiety and depressive disorders is effective, acceptable and practical health care.
TiO2 and ZrO2 nanoparticles reinforced Ni–W-based composite coatings were prepared on mild steel substrate via pulse electrodeposition technique under constant operating parameters. During the ...deposition process, TiO2 content was maintained constant throughout the process whereas, ZrO2 content has been varied. Phase evolution, microstructure, and compositional changes of coatings were analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive microscopy, respectively. Microhardness and wear tests were conducted on composite coatings to evaluate the surface mechanical properties. The corrosion behaviour of the composite coatings was studied by potentiodynamic polarization and electrochemical impedance spectroscopy in a 3.5% NaCl solution. The topography of certain composite coatings has been examined by an atomic force microscope (AFM). Besides, a wettability test was conducted to study the hydrophobic properties of composite coatings. Experimental results demonstrated that ZrO2 nanoparticle's addition under fixed TiO2 content in deposition bath play a crucial role to improve the surface-mechanical, corrosion, and hydrophobic properties of the coating. The maximum hardness (1074 HV0.05), wear and corrosion properties were observed in Ni–W-5g/L TiO2-15g/L ZrO2 composite coating.
•ZrO2 addition improves surface-mechanical property of Ni–W–TiO2 composite coatings.•Hardness as high as 1074 HV0.05 is obtained in Ni–W-5g/LTiO2-15g/LZrO2 coating.•Coatings display hydrophobic property with a maximum contact angle of 114o.•Remarkable improvement in electrochemical properties with higher addition of ZrO2.
In the present study, an attempt has been made to evaluate the effect of processing route on phase evolution and mechanical properties of CoCrCuFeNiSix (x = 0, 0.3, 0.6 and 0.9 atomic ratios) high ...entropy alloys. The CoCrCuFeNiSix high entropy alloys were prepared through two different routes i.e., spark plasma sintering and vacuum arc melting. The X-ray diffraction results reveal face-centered cubic structure along with σ phase after spark plasma sintering and it is also observed that addition of Si favors σ phase formation. Whereas, sample papered by arc meting route showed face-centered cubic structure up to 0.6 Si content. Further increase in Si (0.6–0.9) leads to the formation of Ni3Si. Enhanced microhardness and superior wear resistance were achieved with the increase in Si content from 0 to 0.9 in both synthesis routes. However, better physical properties were obtained by spark plasma sintered samples compared to the arc melted samples due to the formation of σ phases. Furthermore, comparative analyses were performed based on the parametric approach to study the phase evolution.
•First time effect of Si is investigated in the CoCrCuFeNi high entropy alloys.•First time effect of processing route is investigated in the CoCrCuFeNiSix alloys.•Spark plasma sintered sample revealed two FCC based phases together with σ phases.•Single FCC phase observed with Si = 0, 0.3 and 0.6 in the arc melted samples.•Whereas, with Si = 0.9 leads to Ni3Si phase formations in the arc melted samples.
A single captured image of a real-world scene is usually insufficient to reveal all the details due to under- or over-exposed regions. To solve this problem, images of the same scene can be first ...captured under different exposure settings and then combined into a single image using image fusion techniques. In this paper, we propose a novel probabilistic model-based fusion technique for multi-exposure images. Unlike previous multi-exposure fusion methods, our method aims to achieve an optimal balance between two quality measures, i.e., local contrast and color consistency, while combining the scene details revealed under different exposures. A generalized random walks framework is proposed to calculate a globally optimal solution subject to the two quality measures by formulating the fusion problem as probability estimation. Experiments demonstrate that our algorithm generates high-quality images at low computational cost. Comparisons with a number of other techniques show that our method generates better results in most cases.
This paper presents a comparative evaluation of efficacies of different index tests and analysis techniques (i.e. regression analyses and fuzzy inference system) in predicting uniaxial compressive ...strength (UCS) of granite, schist and sandstone. UCS and indices such as block punch index, point load strength, Schmidt rebound hardness, ultrasonic P-wave velocity, and physical properties (effective porosity and density) were determined for the concerned rocks. From simple regression analyses, it was apparent that for granite and sandstone, performances of all six indices are reasonably good in predicting UCS. In case of granite, block punch index and point load strength are the best indices whereas effective porosity, point load strength and Schmidt rebound hardness are the most efficient indices for sandstone. In case of schist, however, ultrasonic P-wave velocity does not seem to be a competent index unlike other indices where point load strength proves to be the best one. From the critical analysis of the tests results, it was demonstrated and subsequently concluded that index test results of different rock types with different geology should not be clubbed together for statistical correlation with any rock mechanical parameter like UCS.
Both multiple regression analyses and the fuzzy inference system exhibited better predictive performances for UCS than simple regression analyses. In addition to the coefficient of correlation, the Variance Account For (VAF) and the Root Mean Square Error (RMSE) were also calculated to check the predictive performances of these two models and it was found that the predictive performances of both models are comparable. However, one should be cautious while employing multiple regression analysis in predicting UCS, as there is always a chance of cumulating plausible errors that might have remained within individual index test results. On the other hand, fuzzy inference system seems to be an efficient tool in predicting UCS of rock materials from indices because of its efficacy in handling uncertainties in the test results with transparency.
•Different indices were used to predict UCS of granite, schist and sandstone.•Point load strength proved to be the best index in this regard.•Multiple regression and fuzzy inference system analyses were also employed.•Fuzzy inference system appeared to be the most efficient technique in predicting UCS.
Chemical provinces were defined on Mars a decade ago using orbital nuclear spectroscopy of K, Th, Fe, Si, Ca, Cl, and H2O. However, past multivariate analyses yielded three sets of provinces, ...suggesting methodologic variability. Province‐stability to the inclusion of Al and S is also unknown, presenting additional uncertainties for geologic insight. Here we consolidate key multivariate methods to define the first cross‐validated provinces. In southern highlands, the highly incompatible K and Th show non‐uniform distribution with higher values in mid Noachian and Hesperian than late Noachian – early Hesperian volcanic terrains. Silica‐ and Al‐depletion trends from Noachian to Amazonian indicate highly differentiated mantle with variable degree of melting. Late Hesperian lowlands are highly depleted in Al and enriched in K and Th, consistent with volcanic resurfacing from a low‐degree partially melted, garnet‐rich mantle. Furthermore, older volatile‐rich regions such as Medusae Fossae Formation exhibit igneous geochemistry, consistent with water‐limited isochemical weathering throughout Mars's history.
Plain Language Summary
Topographically Mars can be divided into two large regions: southern highlands and northern lowlands. However, the compositional evolution of these two landforms and their source characteristics remains unclear. Therefore, using enhanced satellite nuclear spectroscopic data, we develop a set of consolidated geochemical provinces of Mars using three multivariate analysis techniques. We identified the correlation of distinct geochemical provinces with mapped geologic units, which demonstrates the effect of bedrock composition over bulk soil composition. Our study depicts discrete igneous provinces within the southern highlands, which follow a secular chemical pattern, indicating a highly differentiated mantle source with an evolving formation pressure and degree of melting. The northern lowlands, on the other hand, are uncorrelated with the chemical trend of southern highland provinces, suggesting a distinct evolution. Our findings further reveal that regardless of volatile enrichment, igneous crustal composition dominates over chemical alteration signatures indicating a limited role of liquid water on the martian landscape.
Key Points
We have consolidated three key multivariate methods, yielding the first unified set of chemical provinces of Mars
Igneous geochemistry pervades volatile‐rich regions, consistent with water‐limited isochemical weathering throughout Mars's geologic history
Secular chemical trends suggest complex processes of mantle melting for highlands, which differs from a possibly garnet‐rich lowland source
Rock failure is a serious problem in rock engineering environments. Rock failure modes, however, are complex and difficult to quantify or predict. A comprehensive study on rock failure modes at ...laboratory scale is, therefore, potentially important as it helps recognize the adequacy of the support designed on the basis of the nature of an engineering work. With due need, this paper analyzes the failure modes of granite, schist, and sandstone under uniaxial compression, Brazilian, and point load tests in relation to corresponding strengths. The nature of the principal failure mode changes from axial splitting to shearing along a single plane to multiple fracturing in the case of both granite and sandstone specimens as uniaxial compressive strength (UCS) increases. In the case of schist, specimens failed at low UCS show failure along foliations whereas specimens which do not fail along foliations portray high strength. The relation between failure modes of all three rocks under uniaxial compression and corresponding UCS values was broadly explained in terms of damage evolution of the rocks. Granite and sandstone specimens failed mainly following central or central multiple type of fracturing whereas schist specimens principally failed by layer activation in combination with either central or non-central fractures over the entire range of determined Brazilian tensile strength. In the case of granite and sandstone, central multiple failure mode corresponds to high tensile strength. Descriptions of different failure modes under point loading were presented. It was found that granite and sandstone specimens generally fail through the rock materials in one or more extensional planes containing the line of loading. Failure patterns showing triple junctions correspond to high point load strength indices. In the case of schist, specimens failed along foliations show a low point load strength index whereas specimens failed through material with a single extensional plane result in high strength.
ABSTRACT We present X-ray source catalogs for the 7 Ms exposure of the Chandra Deep Field-South (CDF-S), which covers a total area of 484.2 arcmin2. Utilizing wavdetect for initial source detection ...and ACIS Extract for photometric extraction and significance assessment, we create a main source catalog containing 1008 sources that are detected in up to three X-ray bands: 0.5-7.0 keV, 0.5-2.0 keV, and 2-7 keV. A supplementary source catalog is also provided, including 47 lower-significance sources that have bright ( ) near-infrared counterparts. We identify multiwavelength counterparts for 992 (98.4%) of the main-catalog sources, and we collect redshifts for 986 of these sources, including 653 spectroscopic redshifts and 333 photometric redshifts. Based on the X-ray and multiwavelength properties, we identify 711 active galactic nuclei (AGNs) from the main-catalog sources. Compared to the previous 4 Ms CDF-S catalogs, 291 of the main-catalog sources are new detections. We have achieved unprecedented X-ray sensitivity with average flux limits over the central 1 arcmin2 region of 1.9 × 10−17, 6.4 × 10−18, and 2.7 × 10−17 erg cm−2 s−1 in the three X-ray bands, respectively. We provide cumulative number-count measurements observing, for the first time, that normal galaxies start to dominate the X-ray source population at the faintest 0.5-2.0 keV flux levels. The highest X-ray source density reaches 50,500 deg−2, and 47% 4% of these sources are AGNs ( 23,900 deg−2).
The Schmidt hammer provides a quick and inexpensive measure of surface hardness that is widely used for estimating the mechanical properties of rock material. However, a number of issues such as ...hammer type, normalization of rebound values, specimen dimensions, surface smoothness, weathering and moisture content, and testing, data reduction and analysis procedures continue to influence the consistency and reliability of the Schmidt hammer test results. This paper presents: a) a critical review of these basic issues; and b) the results of tests conducted on granitic rocks of various weathering grades in the light of the conclusions of this review. It was found that a very good correlation exists between L and N hammer rebound values and that both hammers are fairly sensitive to the physical properties, particularly to dry density though less so to effective and total porosities. The N hammer, producing a lesser scatter in the data, proved to be more efficient than the L hammer in predicting uniaxial compressive strength and Young's modulus. The exponential form of the correlation curves was found to reflect microstructural changes during the course of weathering and the differences in the probing scales or mechanisms in the means of measuring these mechanical properties, and could be generalized to other crystalline igneous rocks. The possibility of predicting weathering grades from rebound values was also explored. The changes in the rebound values during multiple impacts at a given point produced a better indication of the weathering grade than a single impact value. It was concluded that increasing the impact energy and plunger tip diameter should significantly reduce the scatter in coarse-grained weathered rocks and hence improve the reliability of the Schmidt hammer as a rock material characterization tool.
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