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In this paper we propose a novel approach to estimating and testing skewness in a stochastic volatility (SV) model. Our key idea is to replace a normal return error in the standard SV model with a split normal error. We show that this simple variation in the model brings about two large computational advantages. First, the SV can be simulated fast and efficiently using a one-block Gibbs sampling technique. Second, more importantly, this is the first to provide a marginal likelihood calculation method to formally test the skewness and SV in a Bayesian framework. We subsequently demonstrate the efficiency and reliability of our posterior sampling and model comparison methods through a simulation study. The simulation study results also show that neglecting skewness leads to inaccurate SV estimates and conditional expected returns. Our empirical applications to daily stock return data also show strong evidence of negative skewness.

Biogas, landfill gas, associated petroleum gas, and other tail gases accompanying various industrial processes are potential sources of hydrogen and carbon monoxide for solid oxide fuel cells via the reforming process. As these gases contain heavy hydrocarbons, fine-tuning of steam and carbon dioxide addition and specific temperature control are necessary to avoid carbon deposition during the reforming process. Numerical simulation plays a crucial role in designing miniaturized steam reforming reactors and optimal working conditions. All simulations of reforming processes must account for carbon deposition. The methods commonly seen in the open literature include Gibbs free energy minimization or parametric equations formalism. This paper utilizes Gaussian process regression as a tool for making predictions about which reforming parameters are suitable for carrying out this process without the danger of damaging the catalyst due to a carbon formation. Parametric equations formalism and Gibbs free energy minimization involve either the minimization of objective function or a search for roots of nonlinear functions. These tasks are sensitive to a choice of the starting points of the algorithm — wrong choice of starting points could lead to numerical instability. Unlike conventional methods, the Gaussian process regression approach bypasses the computation of equilibrium composition. It predicts carbon formation tendencies directly from the initial conditions which ensure stability.

The compatibility problems become main concern in the utilization of biodiesel especially regarding to degradation and corrosion. The present study is conducted to describe the corrosion behaviour that occurs in steel tanks after contact with palm-based biodiesel for a period of 7 months. The storage tank used is respectively made of galvanised steel (GS), carbon steel (CS) and stainless steel (SS). It is performed in vertical cylinders with a floating-roof model. In every 30 days of storage time, the profile changes in the wall, roof and base surface of each tank were observed. The oil fuel properties were monitored in the parameter of viscosity, acid numbers, water content and oil colour. The topographic profiles on the surface of the walls and bottom of each tank wetted by biodiesel were examined over three zones inside the tanks using an endoscope imager. The main results of this study indicate that the tank steel with different protective layers exhibits different types of corrosion. The corrosion was localized in SS tanks but generalized in GS and CS tanks. The oil contamination in SS tanks was relatively lower than that in CS and GS tanks. The type of corrosion performed differently in different zones on the inside of the tank. The potential for leaks is greater at the base than on the walls and roof of the storage tank.

Background Emerging epidemiological evidence suggests that compared to engaging in 1 activity mode alone, a combination of moderate-to-vigorous physical activity (MVPA: brisk walking/jogging, cycling) and muscle-strengthening exercise (MSE: push-ups/sit-ups, using weight machines) has more favorable associations with optimal weight status. However, few studies have examined the dose-dependent and joint associations of MVPA and MSE with obesity. Methods Based on cross-sectional analyses of the European Health Interview Survey Wave 2 (2013–2014), we examined prevalence ratios (PRs) of joint and stratified associations between MVPA (4 categories: (i) 0 min/week, (ii) 1–149 min/week, (iii) 150–299 min/week, and (iv) ≥300 min/week) and MSE (3 categories: (i) 0 day/week, (ii) 1 day/week, and (iii) ≥2 days/week) with body mass index-defined obesity (body mass index of ≥30.0 kg/m2) using Poisson regression with robust error variance. PRs were examined unadjusted and adjusted for sociodemographic and lifestyle characteristics (e.g., sex, age, education, income, and smoking status). Results Data were available for 280,456 adults (≥18 years), of which 46,166 (15.5%) were obese. The interaction MVPA × MSE guideline adherence was statistically significant for obesity (p ≤ 0.05). The joint MVPA–MSE analysis showed that compared to the reference group (i.e., no MVPA and no MSE), the PRs followed a dose-dependent pattern, with the lowest observed among those reporting ≥150 MVPA min/week and ≥1 MSE days/week (PR: 0.43; 95% confidence interval: 0.41–0.46). When stratified across each MVPA strata, the PRs were mostly lower among those engaging in MSE 1 day/week, as compared to those doing MSE ≥2 days/week. Conclusion There was evidence for a dose-dependent association between joint MVPA–MSE with a reduced prevalence of obesity. Public health strategies for the prevention and management of obesity should recommend both MVPA and MSE.

The excellent remote sensing ability of synthetic aperture radar (SAR) will be misled seriously when it encounters deceptive jamming which possesses high fidelity and fraudulence. In this paper, the dynamic synthetic aperture (DSA) scheme is used to extract the difference between the true and false targets. A simultaneous deceptive jamming suppression and target reconstruction method is proposed for a single channel SAR system to guarantee remote sensing ability. The system model is formulated as a sparse signal recovery problem with an unknown parametric dictionary to be estimated. An iterative re-weighted method is employed to jointly handle the dictionary parameter learning and target reconstruction problem in an majorization-minimization framework, where a surrogate function majorizing the Gaussian entropy in the objective function is introduced to circumvent its non-convexity. After dictionary parameter learning, the grid mismatching problem in a fixed grid based method is avoided. Therefore, the proposed method can reap a super resolution result. Besides, a simple yet effective DSA section scheme is developed for the SAR data excerpting, in which only two DSAs are required. Experimental results about location error and reconstruction power error reveal that the proposed method is able to achieve a good performance in deceptive jamming suppression.

We propose a model that allows for conditional heteroskedasticity in the volatility of asset returns and incorporates current return information into the volatility nowcast and forecast. Our model can capture all stylised facts of asset returns even with Gaussian innovations and is simple to implement. Moreover, we show that our model converges weakly to the GARCH-type diffusion as the length of the discrete time intervals between observations goes to zero. Empirical evidence shows that our model has a better fit, a more efficient parameter estimator as well as more accurate volatility and VaR forecasts than other common GARCH-type models.

Fluoride contamination in groundwater is a major concern in many parts of India and all over the world. Researches paying attention for the removal of fluoride through the application of biosorbents prepared from different parts of plants are finding greater scope and importance. The present research work focuses on Senna auriculata L., flower petal biomass as biosorbent, and evaluated its feasibility for fluoride ion elimination from aqueous solutions. Batch experiments were conducted to remove fluoride under different experimental conditions have been optimized for the maximum removal of fluoride; 80% removal was observed at pH: 6, sorbent dosage: 0.25 g/100 mL, time of agitation: 90 min, and initial concentration of the fluoride ions: 5 mg/L. Characterization studies of the biosorbent revealed its favorability towards the sorption of fluoride. In the isothermal modeling studies, Langmuir isotherm model was obeyed by the biosorption process with R2 value of 0.98 and from a kinetic perspective, the biosorption of fluoride onto the biosorbent observed the pseudo-second-order reaction with R2 value of 0.98. The developed biosorbent has been applied to real field fluoride-contaminated water samples and found to be successful.

We introduce a multivariate stochastic volatility model that imposes no restrictions on the structure of the volatility matrix and treats all its elements as functions of latent stochastic processes. Inference is achieved via a carefully designed feasible and scalable MCMC that has quadratic, rather than cubic, computational complexity for evaluating the multivariate normal densities required. We illustrate how our model can be applied on macroeconomic applications through a stochastic volatility VAR model, comparing it to competing approaches in the literature. We also demonstrate how our approach can be applied to a large dataset containing 571 stock daily returns of Euro STOXX index.

In this research, experimental investigation of the coefficient of the heat transfer has been conducted for a set of rectangular fins with different fin height, 0.27, 0.47 and 0.67 m at air velocity test points of 1.1, 1.3, 1.5, 1.7 and 2 m/s, to meet the Reynolds number (Re). Thirty samples from the two cases with changing fin positions were studied to verify the thermal performance of the system. The study was conducted based on the cross-sectional diameter of 21167, 25016, 28864, 32713, and 38486. Total heat flux in all tubes has been settled as 26.3, 58, and 88.7 W/m2. The experimental results showed that the temperature difference between the surface of the block and flowing air increases with increasing Reynolds number for all heat flow states.

Agriculture is the back bone of India, one of the major sources for some notable population from past decade, slowly the agriculture is facing downward growth. Due to less rain fall, they are not getting proper yield, and also expected price for their crops. The farmers are getting loss or less profit. If they know the price of particular commodity, accordingly they can grow selected crop depending upon their geographical area. We can use some of the machine leaning regression algorithms to predict the price of the agricultural commodities that helps the formers to do the decision making. This research work focus on detailed study of predicting the price of the cotton using five different ML regression algorithms namely Linear Regression, Bayesian Linear Regression, Boosted Decision Tree Regression, Decision forest Regression, Poisson Regression. Metrics for evaluating the performance of ML model. The Data set contains the cotton prices of different states of India. The cotton price 2019 data set is used for this work and the prediction values are compared with 2020 data set and the predicted prices are nearing to the actual values. Compare to all other algorithms Boosted decision tree giving the good accuracy, after that Bayesian and Linear regression also performing well.

The degree distributions of complex networks are usually considered to be power law. However, it is not the case for a large number of them. We thus propose a new model able to build random growing networks with (almost) any wanted degree distribution. The degree distribution can either be theoretical or extracted from a real-world network. The main idea is to invert the recurrence equation commonly used to compute the degree distribution in order to find a convenient attachment function for node connections - commonly chosen as linear. We compute this attachment function for some classical distributions, as the power-law, broken power-law, geometric and Poisson distributions. We also use the model on an undirected version of the Twitter network, for which the degree distribution has an unusual shape. We finally show that the divergence of chosen attachment functions is heavily links to the heavy-tailed property of the obtained degree distributions., Comment: 23 pages, 3 figures

Summary Introduction The purpose of the study was to assess acoustic measures of fundamental frequency (fo), standard deviation of fo (SD of fo), jitter%, shimmer%, noise-to-harmonic ratio (NHR), smoothed cepstral peak prominence (CPPS), and acoustic voice quality index analyzed through multiple Praat versions automatically by VoiceEvalU8 or manually by two raters. In addition, default settings to calculate CPPS in two Praat versions manually analyzed by two raters were compared to Maryn and Weenik 20 procedures for CPPS automatically analyzed by VoiceEvalU8. Methods Nineteen vocally healthy females used VoiceEvalU8 to record three 5-s sustained /a/ trials, the all voiced phrase “we were away a year ago,” and a 15-s speech sample twice a day for five consecutive days. Two raters manually completed acoustic analysis using different versions of Praat and compared that analysis to measures automatically generated through a version of Praat used by VoiceEvalU8. One-way analyses of variance were run for all acoustic measures with post-hoc testing by the Bonferroni method. For acoustic measures that demonstrated significant differences, intraclass correlation coefficients were conducted. Results Results showed no significant differences across automatic and manual analysis for different versions of Praat for all acoustic measures during /a/, for fo, jitter%, shimmer%, and NHR during the phrase, for jitter%, shimmer%, NHR, and CPPS during speech, and for acoustic voice quality index calculated from both sustained /a/ and the phrase. The default Praat settings for CPPS were not significantly different from the Maryn and Weenik 20 procedures for sustained /a/ and speech. Significant differences were present for SD of fo and CPPS during the phrase and fo and SD of fo during speech. SD of fo and CPPS in the phrase were moderately correlated and fo and SD of fo during speech demonstrated good to excellent correlations across the different versions of Praat. Conclusions Acoustic measures analyzed through sustained /a/ and some of the acoustic measures during the phrase and speech were not different across multiple versions of Praat. Automatic analysis by VoiceEvalU8 produced similar mean values as compared to manual analysis by two raters. Even though SD of fo and CPPS in the phrase and fo and SD of fo in speech were different across the versions of Praat, the measures demonstrated moderate to excellent reliability.

The prosthetic socket base material must have exhibited good mechanical properties. An experimental investigation about the behavior of different fibers reinforced laminated composite materials were done. This work has been done on seven laminated composites which were prepared by the Vacuum bagging technique from Polyester resin as a bonding matrix and reinforced with (Jute, Glass, Carbon, Perlon) fibers. Laminated specimens were characterized by mechanical tensile tests such as (Tensile Strength, Young’s Modulus, Elongation Percentage) and physical test (density) to measure specific strength and specific modulus. SEM test also had been studied for different laminated composite. The results of experimental work showed that the mechanical properties were changed with the type and number of reinforcing layers. So, the results showed that the best laminated composite specimens have three layers of Jute with four layers of Carbon fiber. Where tensile strength and modulus of elasticity reach (162 MPa. and 3.60 GPa.) respectively. And specific strength and specific modulus reach to (134 MPa.cm3/gm–2.544 GPa.cm3/gm). The smoothness of the fractured surface will increase, indicating a brittle to semi-ductile transformation, according to SEM results.

An algorithm for solving exciton Schrodinger equation in an arbitrary 2D multiple quantum well structure under applied electric field is proposed, allowing one to model both the absorption and refraction spectra consistently and efficiently. It gives much better quantitative results than variational approximation, while being faster than more advanced methods. The algorithm is implemented using R language and tested by comparing to other published results. Possible improvements are discussed.

The randomized treatment allocation process in a response adaptive clinical trial is formulated as a stochastic sequential decision problem and an algorithm is proposed to approximate the optimal value under the average reward criterion. When the information of previous treatment allocations and associated responses are summarized with sufficient statistics for unknown parameters, the decision process becomes a Markov process, on which a span-contractor operator is defined. It is proven that the average reward under the policy identified from the span-contractor operator converges almost surely to the optimal value. Numerical results reveal that the sequential procedure based on the controlled Markov process shows superior ethical advantage and at the same time produces good statistical power for large sample sizes such as 200 or larger.

Recently heavy metal pollution is consider among the most essential environmental issues. Due to their impact, the removing of heavy metals from the environment is a high demanding concern. Heavy metals adsorption is a new technology for wastewater treatment that contain different selected heavy metals types. This study aim to adopted adsorbents with low cost application, in this technique a pine cones used as plant wastes adsorbents in Industrial wastewater treatment by implemented batch technique adsorbent dosage and adsorbate initial concentration). The plant waste sample of (pine cone) was used to test its efficiency which that provide the optimum performance in removing heavy metals and other pollutants (Turbidity, TSS and TDS). Activated carbon produced from Pine cones Turkish Pine (ACPC) was adopted as an adsorbent for the Zinc ions removal from wastewater with industrial pollutants. Surface analysis was preform to measure the pore size distribution and specific surface area of the activated carbon produced from pine cone. Optimal parameters, pH, equilibrium time, adsorbent dosage, temperature and mix speed were investigated. Using Langmuir, Freundlech and Elvich isotherm models, equilibrium data were evaluated. Langmuir isotherm model provided the highest fit to the equilibrium data.

Background The aging population is a risk factor for an increase in osteoarthritis, leading to a potential increase in the number of arthroplasties worldwide. This study aimed to calculate the projected numbers of knee and hip arthroplasties in Japan until 2030 using national health insurance claim data. Methods Data on the numbers of knee and hip arthroplasties performed in Japan between 2014 and 2018 were obtained from the National Database of Health Insurance Claims and Specific Health Checkups of Open Data Japan. Demographic data were obtained from the National Institute of Population and Social Security Research. Collected data were categorized into three age subgroups (40–64, 65–74, and ≥75 years) for each sex. Projections were based on the Poisson regression model. Results The number of knee arthroplasties in Japan in 2030 was projected to be 4052 for men aged 40–64 years, 6942 for men aged 65–74 years, 14,986 for men aged ≥75 years, 7092 for women aged 40–64 years, 22,957 for women aged 65–74 years, and 58,340 for women aged ≥75 years. The number of hip arthroplasties in Japan in 2030 was predicted to be 8936 for men aged 40–64 years, 9005 for men aged 65–74 years, 5972 for men aged ≥75 years, 27,327 for women aged 40–64 years, 36,416 for women aged 65–74 years, and 37,011 for women aged ≥75 years. Conclusion The numbers of knee and hip arthroplasties are expected to continue to increase over the next 10 years in Japan in most age groups. These findings are useful for future healthcare resource planning to meet the demand for knee and hip arthroplasties.

We consider a discrete system of $n$ simple indistinguishable devices, called \emph{agents}, forming a \emph{connected} shape $S_I$ on a two-dimensional square grid. Agents are equipped with a linear-strength mechanism, called a \emph{line move}, by which an agent can push a whole line of consecutive agents in one of the four directions in a single time-step. We study the problem of transforming an initial shape $S_I$ into a given target shape $S_F$ via a finite sequence of line moves in a distributed model, where each agent can observe the states of nearby agents in a Moore neighbourhood. Our main contribution is the first distributed connectivity-preserving transformation that exploits line moves within a total of $O(n \log_2 n)$ moves, which is asymptotically equivalent to that of the best-known centralised transformations. The algorithm solves the \emph{line formation problem} that allows agents to form a final straight line $S_L$, starting from any shape $ S_I $, whose \emph{associated graph} contains a Hamiltonian path., Comment: 31 pages, 18 figures

The number of proper vertex-3-colorings of every triangle-free planar graph with n vertices and with no separating cycle of length 4 or 5 is at least 2 n / 17700000 . On the other hand, for infinitely many n, there exists a triangle-free planar graph with separating cycles of length 4 and 5 whose number of proper vertex-3-colorings is 2 15 n / log 2 ⁡ ( n ) .

The concept of graph tessellation cover was defined in the context of quantum walk models, and is a current research area in graph theory. In this work, we propose a generalization called total tessellation cover. A tessellation of a graph G is a partition of its vertex set V ( G ) into vertex disjoint cliques. A tessellation cover of G is a set of tessellations that covers its edge set E ( G ) . A total tessellation cover of G consists of a tessellation cover together with a compatible vertex coloring, such that the color of each vertex is different from the tessellation labels of the edges incident to the vertex. The total tessellation cover number T t ( G ) is the size of a minimum total tessellation cover of G . We present lower bounds T t ( G ) ≥ ω ( G ) and T t ( G ) ≥ s ( G ) + 1 , where ω ( G ) is the size of a maximum clique, and s ( G ) is the number of edges of a maximum induced star subgraph. A graph G is called a good total tessellable if T t ( G ) = ω ( G ) or T t ( G ) = s ( G ) + 1 . We study the complexity of the k - total tessellability problem, which aims to decide whether a given graph G has T t ( G ) ≤ k . We prove that k - total tessellability is in P for good total tessellable graphs. We establish the NP -completeness of the k - total tessellability when restricted to the following graph classes: bipartite graphs, line graphs of triangle-free graphs, universal graphs, ( 2 , 1 ) -chordal graphs and planar graphs.

What does it mean today to study a problem from a computational point of view? We focus on parameterized complexity and on Column 16 “Graph Restrictions and Their Effect” of D.S. Johnson’s Ongoing guide, where several puzzles were proposed in a summary table with 30 graph classes as rows and 11 problems as columns. Several of the 330 entries remain unclassified into Polynomial or NP -complete after 35 years. We provide a full dichotomy for the Steiner Tree column by proving that the problem is NP -complete when restricted to Undirected Path graphs. We revise Johnson’s summary table according to the granularity provided by the parameterized complexity for NP -complete problems.

Forward and backward reaching inverse kinematics (FABRIK) is an efficient two-stage iterative solver for inverse kinematics of spherical-joint manipulator without the calculation of Jacobian matrix. Based on FABRIK, this paper presents an incremental control scheme for a free-floating space manipulator consists of revolute joints and rigid links with the consideration of joint constraints and dynamic coupling effect. Due to the characteristics of FABRIK, it can induce large angular movements on specific joints. Apart from that, FABRIK maps three dimensional (3D) problem into two dimensional (2D) problem by a simple geometric projection. This operation can cause infinite loops in some cases. In order to overcome these issues and apply FABRIK on space manipulators, an increments allocation method is developed to constrain the angular movements as well as to re-orient the end-effector. The manipulator is re-positioned based on the momentum conservation law. Instead of pure target position tracking, the orientation control of the end-effector is also considered. Numerical simulation is performed to testify and demonstrate the effectiveness and reliability of the proposed incremental control approach.

Rainbow coloring problems, of noteworthy applications in Information Security, have been receiving much attention in the last years in Combinatorics. In particular, the rainbow connection number of a connected graph G , denoted r c ( G ) , is the least k for which G admits a (not necessarily proper) k -edge-coloring such that between any pair of vertices there is a path whose edge colors are all distinct. When G is disconnected, we define r c ( G ) = ∞ . A graph G is rainbow critical if the deletion of any edge of G increases r c ( G ) . In this paper we determine the rainbow connection number for the shadow graphs of paths, some circulant graphs, and some Cartesian products involving cycles and paths. We also determine conditions for the rainbow criticality and non-criticality of wheels, fans, and some Cartesian products involving cycles, paths, pans, and complete graphs.

Understanding the attitude of elderly patients is important for successful complete denture therapy. However, data regarding the impact of sociodemographic factors, impact of medical comorbidities, and duration of edentulism on the mental attitudes of such patients are lacking.The purpose of this clinical study was to explore the association of sociodemographic factors, duration of edentulism, and medical comorbidities on the attitudes of completely edentulous patients.The study was conducted among 125 completely edentulous patients visiting the Department of Prosthodontics, Nepal Medical College from August 2020 to October 2020. General information including age, sex, education level, medical history, and duration of edentulism were collected during a routine clinical evaluation. The mental attitudes of the participants were categorized according to M.M. House Classification into philosophical mind, exacting mind, hysterical mind, or indifferent mind. The participants were categorized into 3 age groups: 45 to 54 years, 55 to 64 years, and 65 years and above. Similarly, they were divided into 3 categories depending upon the duration of edentulism: 0 to 2 years, 2 to 5 years, and more than 5 years. Data were entered in a statistical software program for descriptive analysis using frequency distributions, and the chi-square statistical test and the Freeman-Halton extension of the Fisher exact test were used to determine the association between categorical variables.The highest number of participants was in the philosophical category (34.4%) with the fewest in the hysterical group (12%). Men had more philosophical and indifferent attitudes, whereas women were more exacting (P.001). Those with a recent history of extraction had an increased exacting attitude (P.001). The respondents without any comorbid diseases were more philosophical, whereas a higher percentage of respondents with different comorbid conditions were assessed to be in the hysterical category (P.001). Significant relationships were not found between mental attitude and educational status or age (P.05).Socioeconomic factors, duration of edentulism, and existing comorbidities had a significant impact on the attitudes of edentulous patients. The role of these factors should be assessed during the appraisal of the mental attitudes of edentulous patients.

Fractional order nonlinear evolution equations have emerged in recent times as being very important model for depicting the interior behavior of nonlinear phenomena that exist in the real world. In particular, Schrodinger-type fractional nonlinear evolution equations constitute an aspect of the field of quantum mechanics. In this study, the (2 + 1)-dimensional time-fractional nonlinear Schrodinger equation and (1 + 1)-dimensional time-space fractional nonlinear Schrodinger equation are revealed as having different and novel wave structures. This is shown by constructing appropriate analytic wave solutions. A successful implementation of the advised rational ( 1 / ϕ ′ ( ξ ) ) -expansion method generates new outcomes of the considered equations, by comparing them with those already noted in the literature. On the basis of the conformable fractional derivative, a composite wave variable conversion has been used to adapt the suggested equations into the differential equations with a single independent variable before applying the scheme. Finally, the well-furnished outcomes are plotted in different 3D and 2D profiles for the purpose of illustrating various physical characteristics of wave structures. The employed technique is competent, productive and concise enough, making it feasible for future studies.

s Flower-like BiOI and Bi5O7I photocatalysts were synthesized by a microwave-assisted solvothermal process and then calcined at various temperatures. The effects of calcination temperature on the phase structure, crystal property, morphology, color, optical property, and activity of the photocatalysts were investigated. As the calcination temperature increased, a blue shift was observed in the diffuse reflection spectra and the band gap increased. After the calcination treatment at 500 °C, the XRD, Raman spectra, and TEM results confirmed that BiOI transformed to Bi5O7I. Although flower-like microspheres still existed, the shapes of building blocks changed from lamellar nanoplates to thick twisted stripes when the BiOI transformed to Bi5O7I. BiOI with a calcination treatment at 300 °C exhibits an improved H2 production activity of 1373 μmol g−1 h−1. The XRD spectra reveal that the B-400 photocatalyst was a Bi5O7I-rich and BiOI-deficient composite material. Fewer Bi5O7I–BiOI interfaces and lower light absorption may be the reasons why the B-400 photocatalyst with Bi5O7I–BiOI compositions did not exhibit higher activity than B-300 (pure BiOI) and B-500 (pure Bi5O7I) photocatalysts.

Objective Breast cancer and breast tumors have been considered to be the most pervasive form of cancer in medical practice. Breast tumors are life-threatening to women, and their early detection could save lives with the proper treatment. Physical methods for detection of Breast Cancer are time-consuming and often prone to a misdiagnosis at classifying tumors. Recent trends in radiological imaging have significantly improved the efficiency and veracity of breast tumor classification. Artificial intelligence techniques could be used as an automated detection and classification system. Materials and methods In this research, we propose a novel configuration of a Stacking Ensemble with custom Convolutional Neural Network architectures to classify breast tumors from ultrasound images into ‘Normal’, ‘Benign’, and ‘Malignant’ categories. Results After thorough experimentation, our ensemble has performed with an accuracy, f1-score, precision, and recall of 92.15%, 92.21%, 92.26%, 92.17% respectively. Conclusion The presented ensemble leverages three Stacked Feature Extractors coupled with a characteristic meta-learner to provide an overall balanced classification performance, with better accuracy and lower false positives. The architecture works in association with gaussian dropout layers to improve the computation and an alternative pooling scheme to retain essential features.

Bulk La2O3-Ga2O3-ZrO2 (LGZ) glass and Tm3+/Yb3+ co-doped LGZ glasses were synthesized successfully using containerless technique. Raman spectra result reveals that the matrix sample possesses the low highest phonon energy of ∼ 642 cm–1. The glasses show good compatibility between large Abbe numbers (>31) and high refractive indices (nd > 1.93). Moreover, transmittance measurements reflect the glasses have high infrared transmittance of ∼ 81.9%, small OH– absorption coefficient and long mid-infrared cut-off wavelengths (∼7.5 μm). The surface morphology of host glass was characterized by SEM micrograph and EDS tests reflect that the doped compositions are distributed into the matrix glass homogeneously. The results of thermal analysis show that the glasses have good thermal properties (Tg > 769 °C). Excited by 980 nm laser, an intense 1810 nm fluorescence is obtained originating from the transition: 3F4 → 3H6 of Tm3+ ion, accompanied by upconversion emission. It can be observed that 1810 nm fluorescence has the highest intensity at 1 mol% Yb2O3 and owns broad full width at half-maximum (>245 nm), the luminescence intensity of 3F4 → 3H6 transition increases with rising temperature from 300 to 550 K. Furthermore, the value of energy transfer efficiency shows that Yb3+ can transfer energy to Tm3+ effectively. By fitting the attenuation curves, the lifetimes of 1810 and 474 nm emission can be acquired.

Glycine functionalized activated carbon adsorption material (NOPAC-GLY-X) was successfully prepared by one-step thermal decomposition using agricultural waste navel orange peel as a precursor. Through batch adsorption experiments, it is found that the adsorption performance of Gd(III) on activated carbon can be significantly enhanced by glycine modification. The adsorption isotherms of the NOPACs conformed to the Langmuir isotherm model, and the maximum adsorption capacity of the activated carbon sample NOPAC-Gly-60 is approximately 48.5 mg/g. The Gd(III) adsorption capacity of navel orange peel activated carbon can be doubled after glycine modification, and the adsorption efficiency of gadolinium can reach 99% at pH=7. The physicochemical properties of the prepared adsorbents were characterized by BET, FTIR, EA, and XPS. The characterization test shows that the specific surface area of the sample increases from 1121 to 1523 m2/g, and the ratio of (N+O)/C increases from 10.8% to 30.0% by the glycine modification. After five cycles of adsorption-desorption, the adsorption capacity can still be maintained at 88% of the initial capacity. NOPAC-GLY-60 has excellent adsorption selectivity for Gd(III). With the obvious advantages of simple synthesis steps and low cost, the activated carbon modification method adopted in this study has great application value in the field of rare earth adsorption and recovery.

Inexpensive Cu2ZnZnS4 (CZTS) films using a two-step method have been developed for use in photovoltaic devices. Gavalnostatic electroplating precursors from environmentally friendly electrolytes and sulfurization were implemented in this method. Optimized sequential electrodepositions of Cu, Sn, and Zn films were carried out on molybdenum-coated glass, while the sulfurization of Mo/Cu/Sn/Zn precursors was performed at 500 °C or 550 °C in a sealed quartz tube filled with argon. The produced CZTS films were characterized in detail by photoelectrochemical measurements (PECMs, as photoelectrocatalytic detections), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), Raman microspectroscopy, X-ray diffraction (XRD), and UV-Vis spectroscopy. PECMs revealed a photocurrent of “copper poor” CZTS sulfurized at 550 °C up to 1.5 mA/cm2, much higher than that of “copper rich” CZTS sulfurized at 550 °C (0.1 mA/cm2). SEM showed Sn particles were dispersed in the precursors, and the morphologies of “copper poor” CZTS showed less crevices and/or pinholes than those of “copper rich” CZTS. EDX analysis showed only Zn-loss could be found after the sulfurization. Raman imaging revealed the uniform composition of “copper poor” CZTS sulfurized at 550 °C, while “copper rich” CZTS processed at the same temperature contained binary compound SnS2 interposing the CZTS. The results of both XRD and Raman depicted that all CZTS films possessed kesterite structure. A direct band gap of about 1.45 eV for the produced CZTS film was determined from UV-Vis spectroscopy. All the measurements demonstrated that the CZTS film fabricated by galvanostatic electroplating meets the requirements for a light-absorbing layer and is a potential candidate for assembling CZTS solar cells. The J-V measurement of the resulting device confirms this assertion, and demonstrates a 5.0% conversion efficiency of the CZTS solar cell.

Sulfolane is an important aprotic polar solvent. Liquid-liquid equilibrium (LLE) data for the ternary systems of water + 1,2-dichloroethane + sulfolane were measured at temperatures of 288.15, 298.15 and 308.15 K under the atmospheric pressure. The distribution coefficient and selectivity were determined from the measured LLE data, which showed that 1,2-dichloroethane is a suitable extractant for the recovery of sulfolane from its aqueous solution. The nonrandom two-liquid (NRTL) model and the universal quasi-chemical (UNIQUAC) model were utilized to correlate the experimental LLE data. The low values of RMSD indicated that the ternary system could be fitted well by the NRTL and UNIQUAC models. The consistency of the binary interaction parameters for the two thermodynamic models obtained was confirmed by the topological information contained in the Gibbs energy of mixing function (GM/RT).

Oxygen-assisted high temperature solid-state reaction approach was employed for the fabrication of Pr activated Ba(Mg0.28Zr0.16Ta0.56)O3 transparent ceramic phosphor. Retiveld refinement of X-ray diffraction pattern was carried out to reveal the lattice parameters and crystal structural information. Under the blue-light excitation of λex=473 nm, the phosphor exhibits a sharp intense red emission centered at 645 nm, accompanied by serval other weak peaks. PL evolution with temperature shows a significant luminescence quenching behavior, and the underlying multi-phonon interaction with optical center is revealed by proposing an unprecedent theoretical calculation work. Such a phonon effect is further confirmed from the red-shift of peak position with temperature, and the involved phonon energy of 50.7 meV is determined from Raman scattering measurement. More interestingly, the fitted results of transient-state PL spectra show a fluctuation of luminescence lifetime at various temperatures, further indicating a significant effect of phonon vibration in the system.

We introduce and study a new graph representation where vertices are embedded in three or more dimensions, and in which the edges are drawn on the projections onto the axis-parallel planes. We show that the complete graph on $n$ vertices has a representation in $\lceil \sqrt{n/2}+1 \rceil$ planes. In 3 dimensions, we show that there exist graphs with $6n-15$ edges that can be projected onto two orthogonal planes, and that this is best possible. Finally, we obtain bounds in terms of parameters such as geometric thickness and linear arboricity. Using such a bound, we show that every graph of maximum degree 5 has a plane-projectable representation in 3 dimensions., Accepted at CALDAM 2020

Cutting tool condition directly affects machining quality and efficiency. In order to avoid severely worn tools used during machining process and fully release the remaining useful life in the meanwhile, a reliable evaluation method of remaining useful life of cutting tools is quite necessary. Due to the variation of cutting conditions, it is a challenge to predict remaining useful life of cutting tools by a unified model. In order to address this issue, this paper proposes a method for predicting the remaining useful life of cutting tools in variable cutting conditions based on Gaussian process regression model incorporated with tool wear mechanism, where the predicted value at adjacent moments is constrained to a linear relationship by the covariance matrix of Gaussian model based on the assumption of progressive tool wear process, so the wear process under continuous changing conditions can be modelled. In addition to that, the input feature space and the output of the model are also enhanced by considering the tool wear mechanism for improving prediction accuracy. Machining experiments are performed to verify the proposed method, and the results show that the proposed could improve the prediction of tool remaining useful life significantly.

In this research article, the perturbed nonlinear Schrodinger equation (P-NLSE) is examined by utilizing two analytical methods, namely the extended modified auxiliary equation mapping and the generalized Riccati equation mapping methods. Consequently, we establish several sorts of new families of complex soliton wave solutions such as hyperbolic functions, trigonometric functions, dark and bright solitons, periodic solitons, singular solitons, and kink-type solitons wave solutions of the P-NLSE. Using the mentioned methods, the results are displayed in 3D and 2D contours for specific values of the open parameters. The obtained findings demonstrate that the implemented techniques are capable of identifying the exact solutions of the other complex nonlinear evolution equations (C-NLEEs) that arise in a range of applied disciplines.

Chromic oxide (Cr2O3) monolayer is a promising alternative hydrogen evolution reaction (HER) catalyst compared with expensive platinum (Pt) due to its advantages such as low cost, large specific surface area, high reserves, and designability. In this study, the two practical strategies, strain engineering and transition metal (TM) doping (Mn, Fe, Zn, etc.), are proposed to activate the catalytic sites of Cr2O3 monolayer for the HER. The density functional theory (DFT) calculations demonstrate that the strained Cr2O3 monolayer can stimulate the HER activity with the Gibbs free energy of hydrogen adsorption (ΔGH∗) close to 0.09eV, which can be considered as a performable strategy to tune the HER catalytic behavior of Cr2O3 monolayer. For the TM doping, it also plays a role in the performance adjustment. These results provide a guideline to optimize the HER performance of Cr2O3 monolayer.

The eternal vertex cover problem is a variant of the classical vertex cover problem defined in terms of an infinite attacker–defender game played on a graph. In each round of the game, the defender reconfigures guards from one vertex cover to another in response to a move by the attacker. The minimum number of guards required in any winning strategy of the defender when this game is played on a graph G is the eternal vertex cover number of G , denoted by evc ( G ) . It is known that given a graph G and an integer k , checking whether evc ( G ) ≤ k is NP-hard. Further, it is known that for any graph G , mvc ( G ) ≤ evc ( G ) ≤ 2 mvc ( G ) , where mvc ( G ) is the vertex cover number of G . Though a characterization is known for graphs for which evc ( G ) = 2 mvc ( G ) , a characterization of graphs for which evc ( G ) = mvc ( G ) remained as an open problem, since 2009. We achieve such a characterization for a class of graphs that includes chordal graphs and internally triangulated planar graphs. For biconnected chordal graphs, our characterization leads to a polynomial time algorithm for precisely determining evc ( G ) and an algorithm for determining a safe strategy for guard movement in each round of the game using only evc ( G ) guards. Though the eternal vertex cover problem is only known to be in PSPACE in general, it follows from our new characterization that the problem is in NP for locally connected graphs, a graph class which includes all biconnected internally triangulated planar graphs. We also provide reductions establishing NP-completeness of the problem for biconnected internally triangulated planar graphs. As far as we know, this is the first NP-completeness result known for the problem for any graph class.

In this paper, we study the Cartesian product of signed graphs as defined by Germina, Hameed and Zaslavsky (2011). Here we focus on its algebraic properties and look at the chromatic number of some Cartesian products. One of our main results is the unicity of the prime factor decomposition of signed graphs. This leads us to present an algorithm to compute this decomposition in linear time based on a decomposition algorithm for oriented graphs by Imrich and Peterin (2018). We also study the chromatic number of a signed graph, that is the minimum order of a signed graph to which the input signed graph admits a homomorphism, of graphs with underlying graph of the form P n □ P m , of Cartesian products of signed paths, of Cartesian products of signed complete graphs and of Cartesian products of signed cycles.

Ionic liquids (ILs) have attracted increasing attention since last few decades due to their high molecular design abilities and wide applications in different fields. In this study, four novel fluorescent isoquinolino [2,1-a]quinoxalin-5-ium ILs were designed and synthesized via a two-step process including a simple dual Schiff's base formation and a subsequent [RhCp∗Cl2]2-catalyzed oxidative C–H activation/annulation reaction. The as-synthesized ILs were extensively characterized using FT-IR, 1H-NMR, 13C-NMR, 19F-NMR, HSQC-NMR, HMBC-NMR and HR-MS. Their photophysical properties were determined by steady-state fluorescence spectroscopy. The results demonstrate that all these ILs showed dual or triple emissions, large stokes shift (90 nm) and mechanochromic behaviors. Basing on solvatochromism and titration experiments, it is thought that the emission bands of the ILs are raised from their local excited states, charge transfer states or excited state proton transfer of cations, while the substitute effect of these quinoxaline derived ILs on their stokes shifts is negligible.

Several combinatorial actions of the affine Weyl group of type C ˜ n on triangulations, trees, words and permutations are compared. Addressing a question of David Vogan, we show that, modulo a natural involution, these permutation representations are multiplicity-free. The proof uses a general construction of Gelfand subgroups in the affine Weyl groups of types C ˜ n and B ˜ n .

Restricted star colouring is a variant of star colouring introduced to design heuristic algorithms to estimate sparse Hessian matrices. For k ∈ N , a k -restricted star colouring ( k -rs colouring) of a graph G is a function f : V ( G ) → { 0 , 1 , … , k − 1 } such that (i) f ( x ) ≠ f ( y ) for every edge x y of G , and (ii) there is no bicoloured 3-vertex path ( P 3 ) in G with the higher colour on its middle vertex. We show that for k ≥ 3 , it is NP-complete to test whether a given planar bipartite graph of maximum degree k and arbitrarily large girth admits a k -rs colouring, and thereby answer a problem posed by Shalu and Sandhya (2016). In addition, it is NP-complete to test whether a 3-star colourable graph admits a 3-rs colouring. We also prove that for all ϵ > 0 , the optimization problem of restricted star colouring a 2-degenerate bipartite graph with the minimum number of colours is NP-hard to approximate within n 1 3 − ϵ . On the positive side, we design (i) a linear-time algorithm to test 3-rs colourability of trees, and (ii) an O ( n 3 ) -time algorithm to test 3-rs colourability of chordal graphs.

Given a graph G , we call a partition ( V 1 , V 2 , … , V k ) of its vertex set an induced star partition of G if each set in the partition induces a star. In this paper, we consider the problem of finding an induced star partition of a graph of minimum size and its decision versions. This problem may be viewed as an amalgamation of the well-known dominating set and coloring problems. We obtain the following main results: (1) Deciding whether a graph can be partitioned into k induced stars is NP-complete for each fixed k ≥ 3 and has a polynomial time algorithm for each k ≤ 2 . (2) It is NP-hard to approximate the minimum induced star partition size within n 1 2 − ϵ for all ϵ > 0 . (3) The decision version of the induced star partition problem is NP-complete for subcubic bipartite planar graphs, line graphs (a subclass of K 1 , r -free graphs, r ≥ 3 ), K 1 , 5 -free split graphs and co-tripartite graphs. (4) The minimum induced star partition problem has an r 2 -approximation algorithm for K 1 , r -free graphs ( r ≥ 2 ) and a 2-approximation algorithms for split graphs. We also identify some fixed parameter tractable and exact exponential time algorithms that follow from the literature.

The problem of computing induced subgraphs that satisfy some specified restrictions arises in various applications of graph algorithms and has been well studied. In this paper, we consider the following Balanced Connected Subgraph (shortly, BCS) problem. The input is a graph $G=(V,E)$, with each vertex in the set $V$ having an assigned color, "red" or "blue". We seek a maximum-cardinality subset $V'\subseteq V$ of vertices that is color-balanced (having exactly $|V'|/2$ red nodes and $|V'|/2$ blue nodes), such that the subgraph induced by the vertex set $V'$ in $G$ is connected. We show that the BCS problem is NP-hard, even for bipartite graphs $G$ (with red/blue color assignment not necessarily being a proper 2-coloring). Further, we consider this problem for various classes of the input graph $G$, including, e.g., planar graphs, chordal graphs, trees, split graphs, bipartite graphs with a proper red/blue $2$-coloring, and graphs with diameter $2$. For each of these classes either we prove NP-hardness or design a polynomial time algorithm., 15 pages, 3 figures

The present work aimed to investigate the electrochemical properties of ITO substrates in propylene carbonate (PC) with 0.5 mol/L lithium perchlorate (LiClO4) medium in the presence of elaborated thin films of cerium dioxide pure and doped with manganese at varying percentages Ce1–xMnxO2 (x=0 wt%, 2 wt%, 4 wt% and 6 wt%) were successfully deposited by the spray pyrolysis (SP) technique on the glass substrate and ITO at 450 °C.The effects of manganese (Mn) doping thin films Ce1–xMnxO2 were studied and investigated by using different analyses namely X-ray diffraction (XRD) analysis, Raman spectroscopy method, UV-Vis spectrophotometer technique, atomic force microscopy (AFM) analysis and electrochemical properties. XRD data obtained present a polycrystalline with a face-centred cubic structure of fluorite type. Raman results of thin films undoped and Mn doped show two peaks at 465 and 600 cm–1, this letter due to the formation of extrinsic oxygen vacancies by the incorporation of Mn rate into Ce1–xMnxO2 matrix. Energy dispersive spectroscopy (EDS) data show the presence of Ce, O, and Mn elements in the elaborated films. The AFM results reveal that the surface roughness decreases with increasing Mn rate. Further, band gap energy of thin films decreases with increasing in Mn rate due to the formation of defect state between valence and conduction band. The storage capacity of the elaborated (Ce1–xMnxO2/ITO/PC+LiClO4) electrode reaches a maximum of 1.997 mF in the presence of 6% of Mn.

A novel sliding mode control strategy is proposed to solve the trajectory tracking control problem of an offshore antenna platform, which uses a Stewart-type parallel mechanism and has a large orientation workspace. To obtain comprehensive posture parameters of the offshore antenna platform, a posture compensation algorithm using the information of azimuth and elevation is proposed. Considering known limb lengths, a state observer which based on a super-twisting algorithm is presented to obtain limb velocities. To solve the trajectory-tracking control problem of the platform, a modified nonsingular terminal integral sliding mode controller is proposed. To reduce chattering, the sliding mode controller is equipped with a higher order super-twisting algorithm. The Lyapunov theory was used to prove its stability. Simulation results on a large-orientation workspace offshore antenna platform demonstrate its superiority over three other controllers. Compared with the traditional sliding mode controller with super-twisting algorithm, the integral of the squared error of the proposed control strategy is 49.49% lower.

To realize the three-dimensional stabilization control of fixed-wing unmanned aerial vehicles (UAVs), we analyze the nonholonomic characteristics, constraint non-integrability, and controllability of UAVs. To simplify the trigonometric function term in the dynamics of the UAV and avoid the singularity problem of the Euler angle in describing attitude, we use the quaternion theory to transform the dynamics of the UAV to avoid the complex trigonometric function derivation, which makes the dynamic matrix more concise. Based on this, a continuous periodic time-varying controller (CPTVC) is designed, and the effectiveness of the controller is proved using the homogeneous method. Finally, the results of the hardware in a loop simulation indicated that the exponential stability provided by the feedback controller can realize the three-dimensional stabilization of any initial position.

We develop a theory of modular forms on the groups SO ( 3 , n + 1 ) , n ≥ 3 . This is very similar to, but simpler, than the notion of modular forms on quaternionic exceptional groups, which was initiated by Gross-Wallach and Gan-Gross-Savin. We prove the results analogous to those of earlier papers of the author on modular forms on exceptional groups, except now in the familiar setting of classical groups. Moreover, in the setting of SO ( 3 , n + 1 ) , there is a family of absolutely convergent Eisenstein series, which are modular forms. We prove that these Eisenstein series have algebraic Fourier coefficients, like the classical holomorphic Eisenstein series on SO ( 2 , n ) . As an application, using a local result of Savin, we prove that the so-called “next-to-minimal” modular form on quaternionic E 8 has rational Fourier expansion.

As an endeavor to trace the origin of the active surface sites on La2Ce2O7 compound for OCM reaction, a dissection strategy is adopted in this work. In detail, the reaction performance of pure La2O3, CeO2, the physical mixture of La2O3 and CeO2 (La2O3+CeO2), and the combination of pure La2O3 and CeO2 with different orders in the reactor (La2O3-CeO2 or CeO2-La2O3) has been tested for OCM reaction under the same condition. Individual La2O3, CeO2 and their simple mixing/combination display much lower OCM performance than La2Ce2O7 compound, especially below 700 oC. Therefore, the reaction performance of La2Ce2O7 is not due to a simple accumulation of the two pure oxides. To achieve favorable OCM performance, La and Ce cations must be combined into a stable La2Ce2O7 compound possessing a disordered defective cubic fluorite structure with intrinsic oxygen vacancies. In situ Raman, CO2-TPD, EPR and XPS results have demonstrated on the surface of La2Ce2O7, much larger amount of both O2- species and moderate basic sites have been formed in comparison with the individual metal oxides or their simple mixing/combination, thus it exhibits the optimum reaction performance among all the catalysts.

Let f be an algebraic valued periodic arithmetical function and L ( s , f ) , defined as L ( s , f ) : = ∑ n = 1 ∞ f ( n ) / n s for ℜ ( s ) > 1 , be the associated Dirichlet series. In this paper, we study the vanishing and arithmetic nature of the special values L ( k , f ) when k > 1 is a positive integer. We prove a generalization of the Baker-Birch-Wirsing theorem conditional on the Polylog conjecture. Adopting a new approach, we define an induction operator on the space of periodic arithmetic functions, which makes precise the notion of an “imprimitive” arithmetic function. This enables us to obtain an analog of Okada's criterion for L ( 1 , f ) = 0 and derive a natural decomposition of the vector space O k ( N ) = { f : Z → Q | f ( n + N ) = f ( n ) for all n ∈ Z , L ( k , f ) = 0 } .

A fixed-time trajectory tracking control of autonomous surface vessels (ASVs) subject to unmeasured speed is studied in this work. By using the homogeneity-based Lyapunov method, the unknown system states, including the unmeasured speed and lumped disturbances, are estimated by using a novel extended state observer (ESO) within fixed time. Subsequently, using the estimated states, the task of fixed-time tracking is completed with the aid of a newly proposed output-constrained power integrator method, which makes the vessel position and heading strictly within the predefined output constraints, and the tracking errors can be reduced to a range of zero under the continuous control action. The practical fixed-time stability (FTS) of the closed-loop system is analyzed in the sense of Lyapunov, while the output constraints can be well maintained during maneuvering. Finally, the ascendancy of the designed scheme is exhibited by simulation comparisons.