Curve similarity recognition based rolling bearing degradation state estimation and lifetime prediction

The health state of a rolling bearing keeps changing from a normal state to a slight degradation state followed eventually by a severely degraded state. To make reasonable inspection and maintenance plans, it is necessary to estimate the degradation state and predict the lifetime of a running rolling bearing accurately and in a timely fashion. This paper presents a new method for rolling bearing degradation state estimation and lifetime prediction based on curve similarity recognition. Different from existing methods, this method employs a dynamic time warping algorithm to recognize the curve similarity of those extracted features of rolling bearings in different states of health, which can reflect the intrinsic state of the rolling bearing; it discretizes the bearing degradation state reasonably through curve similarity. Next, the curve similarity is used to train the degradation state estimation model and a support vector machine based lifetime prediction model. Finally, this paper conducts a case study for a rolling bearing with impact degradation and one with wear degradation, respectively. The experimental results indicate that the new proposed method is highly efficient in recognizing the bearing’s degradation state and predicting its lifetime

Rolling bearing health assessment using only normal samples

To take maintenance measures timely and to prolong the lifetime of a bearing as a whole, bearing users need to know the current health state of the bearing. Those existing methods for health assessment are mostly based on fault samples and/or decline samples of bearings. However, the bearings are always not allowed to fail in the practical engineering application in consideration of the enormous harms and great damages might be caused by the bearing fault. So the fault samples or decline samples of bearing are often lacking. In this point of view, this paper presents a quantificational health assessment method for rolling bearing based solely on normal samples and SOM network. To demonstrate the capability of the proposed method, a series of vibration datasets of the bearings under various health states were employed to conduct case study. And this paper expresses the uncertainty of assessment results after training for many times by the probability density function (PDF)

Osteoporosis Associated with Antipsychotic Treatment in Schizophrenia

Schizophrenia is one of the most common global mental diseases, with prevalence of 1%. Patients with schizophrenia are predisposed to diabetes, coronary heart disease, hypertension, and osteoporosis, than the normal. In comparison with the metabolic syndrome, for instance, there are little reports about osteoporosis which occurs secondary to antipsychotic-induced hyperprolactinaemia. There are extensive recent works of literature indicating that osteoporosis is associated with schizophrenia particularly in patients under psychotropic medication therapy. As osteoporotic fractures cause significantly increased morbidity and mortality, it is quite necessary to raise the awareness and understanding of the impact of antipsychotic-induced hyperprolactinaemia on physical health in schizophrenia. In this paper, we will review the relationship between schizophrenia, antipsychotic medication, hyperprolactinaemia, and osteoporosis

Osteoporosis Associated with Antipsychotic Treatment in Schizophrenia

Schizophrenia is one of the most common global mental diseases, with prevalence of 1%. Patients with schizophrenia are predisposed to diabetes, coronary heart disease, hypertension, and osteoporosis, than the normal. In comparison with the metabolic syndrome, for instance, there are little reports about osteoporosis which occurs secondary to antipsychoticinduced hyperprolactinaemia. There are extensive recent works of literature indicating that osteoporosis is associated with schizophrenia particularly in patients under psychotropic medication therapy. As osteoporotic fractures cause significantly increased morbidity and mortality, it is quite necessary to raise the awareness and understanding of the impact of antipsychoticinduced hyperprolactinaemia on physical health in schizophrenia. In this paper, we will review the relationship between schizophrenia, antipsychotic medication, hyperprolactinaemia, and osteoporosis

Predictors of lung adenocarcinoma with leptomeningeal metastases: A 2022 targeted-therapy-assisted molGPA model

Objective: To explore prognostic indicators of lung adenocarcinoma with leptomeningeal metastases (LM) and provide an updated graded prognostic assessment model integrated with molecular alterations (molGPA). Methods: A cohort of 162 patients was enrolled from 202 patients with lung adenocarcinoma and LM. By randomly splitting data into the training (80%) and validation (20%) sets, the Cox regression and random survival forest methods were used on the training set to identify statistically significant variables and construct a prognostic model. The C-index of the model was calculated and compared with that of previous molGPA models. Results: The Cox regression and random forest models both identified four variables, which included KPS, LANO neurological assessment, TKI therapy line, and controlled primary tumor, as statistically significant predictors. A novel targeted-therapy-assisted molGPA model (2022) using the above four prognostic factors was developed to predict LM of lung adenocarcinoma. The C-indices of this prognostic model in the training and validation sets were higher than those of the lung-molGPA (2017) and molGPA (2019) models. Conclusions: The 2022 molGPA model, a substantial update of previous molGPA models with better prediction performance, may be useful in clinical decision making and stratification of future clinical trials

Photoelectrochemical water oxidation of GaP 1−x Sb x with a direct band gap of 1.65 eV for full spectrum solar energy harvesting

International audienceHydrogen produced using artificial photosynthesis, i.e. solar splitting of water, is a promising energy alternative to fossil fuels. Efficient solar water splitting demands a suitable band gap to absorb near full spectrum solar energy and a photoelectrode that is stable in strongly alkaline or acidic electrolytes. In this work, we demonstrate for the first time, a perfectly relaxed GaP0.67Sb0.33 monocrystalline alloy grown on a silicon substrate with a direct band gap of 1.65 eV by molecular beam epitaxy (MBE) without any evidence of chemical disorder. Under one Sun illumination, the GaP0.67Sb0.33 photoanode with a 20 nm TiO2 protective layer and 8 nm Ni co-catalyst layer shows a photocurrent density of 4.82 mA cm−2 at 1.23 V and an onset potential of 0.35 V versus the reversible hydrogen electrode (RHE) in 1.0 M KOH (pH = 14) aqueous solution. The photoanode yields an incident-photon-to-current efficiency (IPCE) of 67.1% over the visible range between wavelengths 400 nm to 650 nm. Moreover, the GaP0.67Sb0.33 photoanode was stable over 5 h without degradation of the photocurrent under strong alkaline conditions under continuous illumination at 1 V versus RHE. Importantly, the direct integration of the 1.65 eV GaP0.67 Sb0.33 on 1.1 eV silicon may pave the way for an ideal tandem photoelectrochemical system with a theoretical solar to hydrogen efficiency of 27%

Propriétés optoélectroniques, vibrationnelles et de transport de parois d’antiphase III-V/Si pour la photonique et la récupération d’énergie solaire

This thesis aims to investigate the specific optoelectronic properties of III-V/Si Anti-Phase Boundaries (APBs) and its use for energy harvesting devices theoretically and experimentally. Strong electron-phonon coupling around stoichiometric APBs are first demonstrated due to simultaneous confinement of charge carriers and phonons in the same region, based on structural and optical characterizations and density functional theory calculations. The GaPSb/Si tandem materials association for solar water splitting is then studied. Combining ellipsometry measurements and tight binding calculations, the bandgap of GaPSb alloys in the whole Sb range and band lineups of GaPSb/Si with water redox levels are obtained, which shows the potential of the GaPSb/Si association for the hydrogen evolution and oxygen evolution reactions. Then a GaP0.67Sb0.33/Si photoanode with an almost optimal bandgap combination (1.7eV/1.1eV) was investigated for photoelectrochemical (PEC) water splitting with promising performances related to efficient sunlight spectrum absorption. Finally, the transport and PEC properties of III-V/Si with vertical non-stoichiometric APBs are investigated from experimental characterizations and first-principle calculations. We demonstrate that epitaxial III-V/Si materials with vertical non-stoichiometric APBs are hybrid structures, composed of bulk photo-active semiconductors with 2D topological semi metallic vertical inclusions, enabling simultaneously good photo-activity, efficient charge transport and separation, and interesting ambipolar properties.L’objectif de cette thèse est d'étudier les propriétés optoélectroniques spécifiques des parois d’antiphase (APBs) III-V/Si et leur utilisation pour des dispositifs de récupération d'énergie solaire, de manière théorique et expérimentale. Un fort couplage électron-phonon autour des APBs stoechiométriques est d'abord démontré en raison du confinement simultané des porteurs de charge et des phonons dans la même région, sur la base de caractérisations structurales et optiques et de calculs de théorie de la fonctionnelle de la densité (DFT). D'autre part, une nouvelle association tandem de matériaux GaPSb/Si pour le craquage de l'eau à partir de l’énergie solaire est étudiée. En combinant des mesures d'ellipsométrie et les calculs de liaisons fortes, la bande interdite des alliages GaPSb pour toutes les concentrations en Sb et les alignements de bande de GaPSb/Si avec les niveaux de l’eau sont obtenus, et montrent le potentiel de ces matériaux pour les réactions d'évolution de l'hydrogène et de l'oxygène. Ensuite, une photoanode GaP0.67Sb0.33/Si avec une combinaison de bandes interdites très proche de l'optimum (1.7eV/1.1eV) a été étudiée pour le craquage de l'eau photoélectrochimique (PEC) et montre des propriétés prometteuses du fait de leur bonne absorption solaire. Le transport et les propriétés PEC des couches III-V/Si avec des APBs verticales non-stoechiométriques sont étudiés sur la base de caractérisations expérimentales et de calculs DFT. Nous démontrons que les matériaux III-V/Si épitaxiés contenant des APBs verticales non stoechiométriques sont des structures hybrides, composées de semi-conducteurs photo-actifs massifs avec des inclusions verticales semi-métalliques topologiques 2D, permettant simultanément une bonne photo-activité, un transport et une séparation efficaces des charges, et des propriétés ambipolaires intéressantes

Strain-induced band-to-band Fermi level tuning in II-VI and III-V antiphase boundaries

International audienceHere, we investigate and analyze the electronic properties of ladder- and zigzag-patterned antiphase boundaries (APBs) in II-VI and III-V semiconductors based on first-principles calculations performed on ZnS and InP. From the band-structure analysis on these configurations, we evidence a direct correlation between Fermi levels positioning and the bond length in ladder-patterned APBs. The changes on the APB bond lengths and electronic properties from III-V to II-VI ladder APBs are discussed based on the charges and atoms electronegativity. We then show how the specific atomic configuration of the zigzag-patterned and ladder-patterned APBs differ from the point of view of force accommodation. As a result, ladder-patterned APBs are found to be much more sensitive to any change of stress or the chemical environment. We finally demonstrate that a small change in the APB bond length deeply modifies the band structure and optoelectronic properties of the systems (for both III-V and II-VI semiconductors), with possible n- and p-doping type inversion, thus opening the way towards APB-engineered photoelectric devices

Analysis and prediction of the summer cooling load characteristics

Nowadays, cooling load is mainly attributable to upgrade of a new high of power grid load. An accurate calculation and prediction of cooling load can better meet power demands at peak hours in summer. Based on the historical summer cooling load and temperature data of Sichuan province, the characteristics of summer cooling load and temperature in Sichuan are examined firstly. Next, the random and nonlinear relations of power load are studied. Finally, the BP neural network model optimized by the genetic algorithm (GA) is employed to achieve accurate prediction of summer cooling load in Sichuan province. Results suggest that cooling load is closely connected with temperature and air-conditioner ownership, and that the BP neural network optimized by the GA is effective in predicting summer cooling load. To sum up, this research can provide solid basis for power load scheduling

Theoretical insight into absolute surface and interface energies, and optoelectronic properties of 2D vertical singularities for III-V/Si heterostructure applications

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