A New Stochastic Model for Systems Under General Repairs

Numerous stochastic models for repairable systems have been developed by assuming different time trends, and re- pair effects. In this paper, a new general repair model based on the repair history is presented. Unlike the existing models, the closed- form solutions of the reliability metrics can be derived analytically by solving a set of differential equations. Consequently, the con- fidence bounds of these metrics can be easily estimated. The pro- posed model, as well as the estimation approach, overcomes the drawbacks of the existing models. The practical use of the proposed model is demonstrated by a much-discussed set of data. Compared to the existing models, the new model is convenient, and provides accurate estimation results

Constrained Optimization Multi-dimensional Harmonic Balance Method for Quasi-periodic Motions of Nonlinear Systems

The constrained optimization multi-dimensional harmonic balance method for calculating the quasi-periodic solutions of nonlinear systems is presented. The problem of determining the worst quasi-periodic response is transformed into a nonlinear optimization problem with nonlinear equality constraints. The general nonlinear equality constraints are built using a set of nonlinear algebraic equations which is derived using the multi-dimensional harmonic balance method. The Multi- Start algorithm is adopted to solve the resulting constrained maximization problem. Finally, the validity of the proposed method is demonstrated with a Duffing oscillator and numerical case studies for problems with uncertainties are performed on a nonlinear two-degree of freedom with non-regular nonlinearities. It is illustrated that the proposed approach can be used to find the worst resonant response and the upper and lower response bounds of quasi-periodic solution and is also able to quantify the combined influences of structural uncertainties and non-regular nonlinearities on the nonlinear quasi-periodic vibrations of nonlinear systems

Simulation-Enhanced Bayesian Optimization of System Designs using Hybrid Physical and Computer Experiments

We consider the problem of learning and optimizing the performance of a system by conducting a limited number of physical and digital experiments within a design space. Physical experiments are assumed to be unbiased but costly, while digital experiments (e.g., simulations) are less expensive but may introduce bias due to the limitations of the simulation model. This problem is relevant in many fields, such as optimizing engineered systems where performance (e.g., mechanical properties and reliability) depends on various design variables and external/internal factors. Without digital experiments, optimizing the system’s performance amounts to evaluating a noisy and expensive-to-assess black-box function, a task commonly handled using Bayesian Optimization (BO). Our research extends BO by incorporating digital experiments between subsequent physical experiments, aiming to (i) improve simulation model calibration and (ii) identify solutions that are likely to generate desirable physical experiment results. We introduce “Simulation-Enhanced Bayesian Optimization” (SEBO), a methodology that integrates these steps, and evaluate it using various one- and two-dimensional benchmark functions. A bias function is used to model the simulation model’s bias across the design space and its parameters. We compare SEBO to traditional BO, with preliminary results demonstrating SEBO’s advantages in optimizing experimental efforts; SEBO outperforms traditional BO for well-behaved functions, requiring fewer physical and digital experiments to achieve a desired objective function value. By effectively combining physical and digital experiments, SEBO offers significant potential for improving the design and optimization of engineered systems, reducing costs, speeding up design processes, and overall providing more efficient solutions in engineering and manufacturing.https://scholarworks.uark.edu/hnrcsturpc25/1016/thumbnail.jp

Multifocal visual evoked potentials (mfVEP) for the detection of visual field defects in glaucoma: systematic review and meta-analysis

14 p.Some discrepancies have been observed in the diagnostic efficacy of multifocal visual evoked potential (mfVEP) when evaluating visual field defects in glaucoma patients. Therefore, we evaluated the diagnostic precision of the mfVEP in glaucoma to find its best diagnostic indicator. A systematic review and meta-analysis of quantitative studies published up to 1 April 2021 was performed. The methodological quality of the included articles was assessed. Publication bias analysis and heterogeneity tests were performed. The sensitivity, specificity and diagnostic odds ratio were calculated. The area under the curve (AUC) was calculated using the summary of receiver operating characteristics curve. Six studies with a total of 241 patients were included according to the inclusion and exclusion criteria. The AUC was 0.98. There was no evidence of publication bias or threshold effect. The pooled sensitivity and pooled specificity of the mfVEP amplitude for detection of visual field defects in all studies was 0.93 and 0.89, respectively. The positive and negative likelihood ratios of mfVEP amplitude were 6.56 and 0.08, respectively. The amplitude of mfVEP showed a good diagnostic precision in the prediction of visual field defects. Interocular mfVEP amplitude analysis can be a good diagnostic indicator for visual field study.Ministerio de Economía y CompetitividadInstituto de Salud Carlos II

Advances in Acute Myeloid Leukemia Stem Cells

As a common hematological malignant tumor, acute leukemia is believed to originate from a subpopulation of special cancer cells, named cancer stem cells. Cancer stem cells are recognized to be the main source of tumor origin, multidrug resistance, metastasis, and recurrence. Leukemic stem cells (LSCs) were first identified and confirmed to play an important role in the occurrence and development of leukemia. In this article, we summarize the following content: special markers and sorting methods for acute myeloid leukemia stem cells and the role of cancer stem cells in treatment resistance, metastasis and invasion, recurrence, and target treatment of acute leukemia

A density functional study of the effect of hydrogen on electronic properties and band discontinuity at anatase TiO2/diamond interface

Tailoring the electronic states of the dielectric oxide/diamond interface is critical to the development of next generation semiconductor devices like high-power high-frequency field-effect transistors. In this work, we investigate the electronic states of the TiO2/diamond 2 × 1-(100) interface by using first principles total energy calculations. Based on the calculation of the chemical potentials for the TiO2/diamond interface, it is observed that the hetero-interfaces with the C-OTi configuration or with two O vacancies are the most energetically favorable structures under the O-rich condition and under Ti-rich condition, respectively. The band structure and density of states of both TiO2/diamond and TiO2/H-diamond hetero-structures are calculated. It is revealed that there are considerable interface states at the interface of the anatase TiO2/diamond hetero-structure. By introducing H on the diamond surface, the interface states are significantly suppressed. A type-II alignment band structure is disclosed at the interface of the TiO2/diamond hetero-structure. The valence band offset increases from 0.6 to 1.7 eV when H is introduced at the TiO2/diamond interface

Difficulties in Chinese-Japanese Translation of Legal Terms from the Perspective of the Homographs in Japanese and Chinese

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Preparation and Crystallization Property of Ternary Composites of WBG/AA-RCC/PP

A series of ternary composites of WBG/AA-RCC/PP were prepared and their crystallization behaviors were investigated by XRD and DSC. The results indicate that WBG and AA-RCC affect the crystallization of PP matrix with a mutual inhibition effect. This effect is enhanced with increasing content of WBG and induces the growth ofβ2crystal. AA-RCC promotes the heterogeneous nucleation ofαcrystal and offers a template forαcrystal growth along a specific lattice plane and promotes the epitaxial crystallization of PP matrix, while the specific arrangedαcrystal could induce the formation ofβcrystal.</jats:p