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Fused contactors and thermal magnetic circuit breakers are commonly applied protective devices in power distribution systems to protect the circuits when short-circuit faults occur. A power distribution system may contain various makes and models of protective devices, as a result, customizable simulation models for protective devices are demanded to effectively conduct system-level reliable analyses. To build the models, thermal energy-based data analysis methodologies are first applied to the protective devices’ physical properties, based on the manufacturer’s time/current data sheet. The models are further enhanced by integrating probability tools to simulate uncertainties in real-world application facts, for example, fortuity, variance, and failure rate. The customizable models are expected to aid the system-level reliability analysis, especially for the microgrid power systems.

Addressing the scientific problem that the profile modification design of tapered roller bearings primarily focuses on contact stress and fatigue life while neglecting its impact on wear evolution, this paper, based on Hertzian contact theory and the Archard wear theory, and considering centrifugal force, gyroscopic effect, and the complex contact state between rollers and raceways, constructed a comprehensive analysis framework integrating a quasi-static model for profiled rollers and a wear depth calculation model. This framework is novel in that it systematically couples roller profile modification parameters with raceway wear evolution under both pure axial and combined radial–axial loads. The validity and effectiveness of the proposed model were verified by comparing the results of the quasi-static model with load distribution data from existing literature and through measurements conducted on a specially designed bearing wear test platform. The main findings are as follows: (1) When the logarithmic modification parameter f1 increases from 0.7 μm to 3.6 μm, the maximum wear depth of the inner raceway increases by 133% under pure axial load and 144% under combined load, while that of the outer raceway increases by 142% under pure axial load and expands from 0.1–0.2 μm to 0.23–0.52 μm under combined load. (2) Combined load induces significant asymmetric wear on the outer raceway, and the difference between the two wear peaks increases from 0.13 μm to 0.35 μm as f1 rises from 0.7 μm to 3.6 μm. (3) The wear peak shifts toward the midpoint of the roller generatrix with increasing modification amount. These results provide important guidance for the wear-oriented optimization design of tapered roller bearings.

A comprehensive quasi-static model of the tapered roller bearing with the modified roller element is established. Based on the slicing method, the wear depth models of both roller element and raceway are derived. The influences of roller element modification on the wear depth distribution characteristics of both roller element and raceway under different load conditions are investigated. The contact pressure distribution between roller element and raceway before and after wear are compared and analyzed. The results indicate that the modification of roller element has a significant effect on bearing wear. The smaller the modification amount, the lower the peak wear depth, and the peak wear position is closer to the end of the roller elements. Wear has a weak impact on the contact force between the roller element and the raceway, but leads to the increase of the peak contact pressure.

This paper concerns the problem of constructing C 1 (continuously differentiable) controllers to stabilize a class of uncertain non-linear systems whose linearization around the origin may contain uncontrollable modes. Based on a new definition of homogeneity with monotone degrees, a polynomial Lyapunov function and a C 1 global stabilizer are constructed recursively. Moreover, several special cases are investigated to show the advantages of the proposed approaches using the generalized homogeneity compared to the existing approaches using the traditional homogeneity.

In the field of nonlinear control, homogeneous systems theory is a powerful tool for stability analysis and controller design of nonlinear systems, mainly owing to the nice properties established for homogeneous systems. However, the applicability of homogeneous systems theory is largely limited since the extant definition of homogeneity is very restrained. In practice, more and more nonlinear models are being developed to capture the complexity of real phenomena in control systems, which are not necessarily homogeneous and therefore cannot be handled by the traditional homogeneity-based approaches. This dissertation focuses on the development of generalized homogeneous methodologies and their applications to general nonlinear systems by relaxing the restriction imposed on the uniform homogeneous degree. In this way, the methodologies obtained in this dissertation will provide new strategies to simplify the stabilizer design process and offer new solutions to analyze and control a wider class of nonlinear systems which cannot be handled by the existing approaches. This dissertation presents a series of methodologies and solutions to control problems of nonlinear systems. Firstly, a polynomial Lyapunov function and a continuously differentiable (C1) global stabilizer with detailed design schemes are recursively constructed based on a modified definition of homogeneity, namely homogeneity with monotone degrees (HWMD). Secondly, for a class of 3-dimensional nonlinear systems, existence condition and explicit design method of smooth (C ∞) controllers are proposed. Several special cases are investigated to show the advantages of HWMD over the existing approaches based on the traditional homogeneity in designing C1 and C ∞ controllers. Thirdly, by adopting and modifying HWMD, a new constructive Lyapunov function and a globally stabilizing small controller are recursively designed in a bottom-to-top manner. This new method not only encompasses the existing results but also achieves more general results for global stabilization of upper-triangular systems. Finally, extensions and applications including finite-time stabilizer design and global stabilization of time-delayed systems are discussed. The significance of this research lies in the development of generalized homogeneous methodologies and more importantly, providing new solutions to control problems of nonlinear systems, particularly in the following directions: (i) continuously differentiable and smooth controllers are constructed by utilizing the flexibility from using HWMD; (ii) a wider class of nonlinear systems, which cannot be handled by existing results, now can be stabilized by using HWMD; (iii) finite-time stability is achieved for a class of nonsmooth systems; and (iv) time-delayed systems can be stabilized by using HWMD-based controllers.

This thesis considers the state estimation and output feedback control of two classes of nonlinear systems: upper-triangular and lower-triangular systems with unmeasurable states. Due to the presence of the high-order nonlinearities, most of the existing state estimation methods can only yield local results. In this thesis, we will show that the newly developed homogeneous observers can be used to estimate the states of some nonlinear systems in larger regions than a small neighborhood of the origin. More specifically, in the case of lower-triangular system, we show that the low-order homogeneous observer will asymptotically converge to the real system when the initial error is small. Under the same condition, we also design an asymptotically convergent high-order observer for the upper-triangular system. The observer is also combined with the output feedback controller to stabilize the upper-triangular systems. To satisfy the requirements of small initial error for the homogeneous observers, we propose a method of estimating the initial values based on the least square estimation method which provides us initial estimation for the homogeneous observer. In addition, we will combine the unscented Kalman filter and the homogeneous observers and thus this combined system will have the ability of filtering noise and estimating the unmeasurable states. Computer simulations are conducted to demonstrate the effectiveness of the proposed method.

Purpose The purpose of this paper is to provide further insight into Chinese wine consumers’ preference, grasp the regional sensory preference differences of China and build up a predictive model for wine consumers’ sensory preferences. Design/methodology/approach The study involved 3,421 Chinese wine consumers in the survey. Classified statistics were conducted to excavate regional differences of wine consumers’ sensory preferences. By analyzing influencing factors, prediction models for consumers’ sensory attribute preferences were constructed on the basis of multivariate disorder logistic regression method. Findings Empirical research showed that the wine with the following sensory attributes was the most preferred by Chinese consumers: dry red, refreshing and soft taste, still type, moderate aroma degree and mellow aroma, and sweet wine was also popular. Consumers’ preference varied from region to region. The proposed predicting method of the study realized more than 70 percent accuracy when conducting prediction for color, sweetness, aroma type and flavor preferences. Social implications By shedding light on the latest sensory attribute preferences of Chinese wine consumers, this study will help wine industry participants conduct market segmentation based on the diversification of consumers’ preferences. The wine enterprises can gain guidance from the results to conduct market positioning, adjust strategies and provide specific production for target wine consumers. Originality/value Based on the actual situation of Chinese wine market, this study defines sensory attribute indexes of wine from the perspective of wine consumers and presents the most recent comprehensive research on the sensory preferences of Chinese wine consumers through a nationwide survey.

Seismic damage investigations and previous studies show that adding wing walls on both sides of frame columns is an economical and practical enhancement measure to improve the seismic performance of reinforced concrete (RC) frames. Quasi-static tests of three 1/3 scale specimens were carried out to study the seismic performance of two schemes, i.e., wing walls mainly bearing lateral load named as functional separation structure, wing walls both bearing lateral and vertical load named as functional integration structure. The damage development, hysteresis behavior, stiffness degradation, energy dissipation capacity, and other seismic behaviors of the specimens were investigated. The obtained results showed that wing walls improved the structural stiffness, bearing capacity and energy dissipation, but reduced the structural ductility. For the two schemes of will walls, the functional integration structure had a higher load-bearing capacity, while the functional separation structure had a better ductility. There was no obvious difference between the seismic performance of the two schemes overall. Furthermore, seven different retrofitting structures were designed, the seismic collapse resistance of the structural systems is evaluated by the increment dynamic analysis (IDA) method, and design suggestions were given.

PurposeThe selection of purchasing channels by wine consumers indirectly affects buying experience and satisfaction, therefore, it is of great practical significance to study consumers' preference on channel selection. The purpose of this study is to investigate the current state of consumer selection for purchasing channel and the corresponding influencing factors.Design/methodology/approachA total of 2,976 valid questionnaires were collected by convenience sampling from 34 provinces, municipalities and autonomous regions of China in 2020 via the Internet, yielding a response rate of 82.2%. A categorical statistical approach was used to understand consumer's selection for each channel. Besides, binary logistic regression model was used to analyze the factors affecting consumers' channel selection.FindingsThe results show that Chinese wine consumers' main purchasing channels are as follows: supermarket/mall, wine specialty stores, comprehensive e-business flagship stores, comprehensive e-business individual stores, restaurants and short video and live streaming platforms. Estimation results showed that among the 12 influencing factors in 4 categories, consumers' education and some other factors significantly influenced consumers' decision on wine purchasing channels.Research limitations/implicationsLimited by time and experimental conditions, this study did not analyze the trend of wine consumers' purchasing channel selection. Future work would concentrate on multi-year data and conduct longitudinal comparative analysis.Originality/valueThis study innovatively subdivides the currently popular wine sales channels in Chinese market and conducts research related to consumer channel selection. The results of the study can provide reference for wine producers and distributors to update their strategic layout and also help various channels to understand the characteristics of their customer groups for targeted marketing.

Hepatocellular carcinoma is the third leading cause of deaths from cancer worldwide. Infection with the hepatitis B virus is one of the leading risk factors for developing hepatocellular carcinoma, particularly in East Asia 1 . Although surgical treatment may be effective in the early stages, the five-year overall rate of survival after developing this cancer is only 50–70% 2 . Here, using proteomic and phospho-proteomic profiling, we characterize 110 paired tumour and non-tumour tissues of clinical early-stage hepatocellular carcinoma related to hepatitis B virus infection. Our quantitative proteomic data highlight heterogeneity in early-stage hepatocellular carcinoma: we used this to stratify the cohort into the subtypes S-I, S-II and S-III, each of which has a different clinical outcome. S-III, which is characterized by disrupted cholesterol homeostasis, is associated with the lowest overall rate of survival and the greatest risk of a poor prognosis after first-line surgery. The knockdown of sterol O-acyltransferase 1 (SOAT1)—high expression of which is a signature specific to the S-III subtype—alters the distribution of cellular cholesterol, and effectively suppresses the proliferation and migration of hepatocellular carcinoma. Finally, on the basis of a patient-derived tumour xenograft mouse model of hepatocellular carcinoma, we found that treatment with avasimibe, an inhibitor of SOAT1, markedly reduced the size of tumours that had high levels of SOAT1 expression. The proteomic stratification of early-stage hepatocellular carcinoma presented in this study provides insight into the tumour biology of this cancer, and suggests opportunities for personalized therapies that target it. A subtype of early-stage hepatocellular carcinoma characterized by disrupted cholesterol homeostasis and associated with a poor prognosis responds to treatment with the SOAT1 inhibitor avasimibe in a patient-derived xenograft mouse model.