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Aiming at the difficulty of analyzing the meshing contact characteristics of gear transmission system under the big data formed by multiple working conditions and uncertain parameters, a meshing contact characteristics analysis method of gear transmission system based on data mining technology is proposed. Based on the principle of multi-dimensional Gaussian distribution and the finite element model of gear transmission system, the meshing contact characteristic data set of the system is constructed. The correlation between system parameters and meshing contact characteristics is analyzed using the maximum information coefficient, which provides a candidate feature subset for the prediction model. Then, the prediction model of meshing contact characteristics of the system is established using support vector machine and random forest algorithm, which realizes the efficient prediction of meshing contact characteristics of the system. The results show that the prediction error of the prediction model based on support vector machine is the smallest, and the average absolute percentage error is 3.87%, which is far less than the theoretical calculation error. Under the optimal feature subset, the prediction error index of contact characteristics of the prediction model based on support vector machine decreases significantly, and its average absolute percentage error reaches 3.03%, which is 21.71% lower than the prediction error of contact characteristics before optimization. These have verified the accuracy and effectiveness of the proposed method.

Permeable concrete is an innovative type of concrete that provides a sustainable solution for stormwater management by allowing water to seep through and be filtered naturally. This study focuses on the preparation and performance investigation of an epoxy resin-based permeable concrete containing ceramsite. In this study, ceramsite, a lightweight aggregate, is used as a substitute for conventional aggregates in the concrete mixture. The epoxy resin is then added to improve the strength and durability of the concrete. A series of tests, including compressive strength, water permeability, and freeze-thaw resistance tests, are conducted to evaluate the performance of the epoxy resin-based permeable concrete. The results show that with an increasing epoxy resin binder–aggregate ratio, the compressive strength of the epoxy resin-based permeable concrete significantly increases while the permeability coefficient decreases. Different types of aggregates have varying effects on the compressive strength and permeability coefficient of epoxy resin-based permeable concrete, with high-strength clay ceramsite providing the highest compressive strength and lightweight ceramsite having the highest permeability coefficient. In addition, the discrete element simulation method effectively and feasibly determines the ultimate load and accurately simulates the compressive strength of the permeable cement-based mixture, consistent with the measured compressive strength. A quadratic polynomial regression analysis yielded an R2 value of around 0.93, showing a strong relationship between durability and freeze-thaw cycles. The findings contribute to the development of sustainable construction materials for stormwater management and offer potential applications in various infrastructure projects. [ABSTRACT FROM AUTHOR]

Aims: The primary objective of this study was to determine the prevalence of workplace violence among nurses in China and its association with demographic characteristics, quality of work life and coping styles. The secondary objective was to explore how nurses deal with workplace violence and the emotional/psychological impact of workplace violence on nurses. Background: Workplace violence is a common occupational hazard that causes physical and psychological harm to nurses. Methods: A cross‐sectional study was conducted with 2769 nurses from China. A demographic information questionnaire, hospital workplace violence questionnaire, Chinese version of the work‐related quality of life scale and coping style scale were used in this study. The Chi‐squared test, Mann–Whitney U test and binary logistic regression analysis were used to investigate the effects of demographic characteristics, quality of work life and coping styles on nurses' workplace violence. Results: A total of 49.12% of the nurses (n = 1360) had experienced at least one type of workplace violence in the past 6 months. Night shifts, work department, chronic diseases (odds ratio [OR] = 1.53, p <.001), sleep disorders (OR = 1.54, p <.001), frequent overtime (OR = 1.78, p <.001), adverse nursing events (OR = 2.01, p <.001) and passive coping (OR = 1.47, p <.001) were risk factors for workplace violence. Working conditions (OR = 0.61, p <.001), general well‐being (OR = 0.65, p <.001) and positive coping (OR = 0.76, p <.001) were identified as protective factors for workplace violence. Nurses exposed to workplace violence experience various negative emotional and psychological consequences. Conclusions: Workplace violence is common among nurses in China. Good working conditions, general well‐being and positive coping may help prevent workplace violence injuries. Implications for nursing management: Efforts should be made to improve and optimize existing workplace violence prevention measures, create and maintain a good working environment for health care workers and develop various coping styles or strategies to manage stress to reduce workplace violence. The cross‐sectional study has been approved by the Ethics Committee of the First Affiliated Hospital of China Medical University, with the registration number 2019‐221‐2. Written informed consent was obtained prior to the survey. [ABSTRACT FROM AUTHOR]

Pervious concrete has been widely used in parking lots and other lightweight streets. This paper investigates the mechanical strength, porosity and permeability of pervious concrete modified with fly ash, silica fume and basalt fibre. Based on the orthogonal design method, a mixture proportion of pervious concrete was obtained with a compressive strength greater than 40 MPa. In addition, three types of failure mode were observed in 28 d compressive strength tests. The addition of basalt fibre can increase the flexural strength and toughness of pervious concrete. X-ray diffraction and scanning electron microscope tests were conducted to investigate the mineral composition, microstructural evolution and micro-mechanism of strength improvement. The test results indicate that the formation of cementitious compounds can lead to densification of the microstructure of the specimens, which primarily improves the mechanical strength of pervious concrete. This modified pervious concrete with high compressive strength (greater than 40 MPa) and flexural strength (up to 5 MPa) can be applied in most municipal projects. [ABSTRACT FROM AUTHOR]

In this paper, we study the fault-tolerant capability of hypercubes with respect to the hamiltonian property based on the concept of forbidden faulty sets. We show, with the assumption that each vertex is incident with at least three fault-free edges, that an n -dimensional hypercube contains a fault-free hamiltonian cycle, even if there are up to (4 n − 1 3) edge faults. Moreover, we give an example to show that the result is optimal with respect to the number of edge faults tolerated. [ABSTRACT FROM AUTHOR]

Highlights • A novel approach to search person with free-form natural language is proposed. • The proposed DSFA-Net is an end-to-end Network. • DSFA-Net has a fusion sub-network and an attention sub-network. • Fusion sub-network provides strong initial matching relations. • Attention sub-network enables discriminative words more visually sensitive. Abstract In the task of searching persons from surveillance videos or large scale image dataset, it is more challenging to utilize free-form natural language to retrieve persons than using images and attributes. Thus, to deal with the challenges brought from the complexity of free-from natural language and visual-description mapping, we propose to strengthen the role of textual descriptions by means of fusion and attention mechanisms to make the discriminative words visually sensitive. Specifically, we develop an end-to-end fusion-attention structure, called Description-Strengthened Fusion-Attention Network (DSFA-Net) to tackle the challenging task. Specifically, DSFA-Net has a fusion sub-network and an attention sub-network, where three attention mechanisms are applied. Extensive experiments are performed on the large-scale CUHK-PEDES, which demonstrate the superiority of DSFA-Net. [ABSTRACT FROM AUTHOR]

Compositional data are known as a sort of complex multidimensional data with the feature that reflect the relative information rather than absolute information. There are a variety of models for regression analysis with compositional variables. Similar to the traditional regression analysis, the heteroskedasticity still exists in these models. However, the existing heteroskedastic regression analysis methods cannot apply in these models with compositional error term. In this paper, we mainly study the heteroskedastic linear regression model with compositional response and covariates. The parameter estimator is obtained through weighted least squares method. For the hypothesis test of parameter, the test statistic is based on the original least squares estimator and corresponding heteroskedasticity-consistent covariance matrix estimator. When the proposed method is applied to both simulation and real example, we use the original least squares method as a comparison during the whole process. The results implicate the model's practicality and effectiveness in regression analysis with heteroskedasticity. [ABSTRACT FROM AUTHOR]

The logratio methodology is not applicable when rounded zeros occur in compositional data. There are many methods to deal with rounded zeros. However, some methods are not suitable for analyzing data sets with high dimensionality. Recently, related methods have been developed, but they cannot balance the calculation time and accuracy. For further improvement, we propose a method based on regression imputation with Q-mode clustering. This method forms the groups of parts and builds partial least squares regression with these groups using centered logratio coordinates. We also prove that using centered logratio coordinates or isometric logratio coordinates in the response of partial least squares regression have the equivalent results for the replacement of rounded zeros. Simulation study and real example are conducted to analyze the performance of the proposed method. The results show that the proposed method can reduce the calculation time in higher dimensions and improve the quality of results. [ABSTRACT FROM AUTHOR]

The standard regression model designed for real space is not suitable for compositional variables; it should be considered, whether the response and/or covariates are of compositional nature. There are usually three types of multiple regression model with compositional variables: Type 1 refers to the case where all the covariates are compositional data and the response is real; Type 2 is the opposite of Type 1; Type 3 relates to the model with compositional response and covariates. There have been some models for the three types. In this paper, we focus on Type 3 and propose multiple linear regression models including model in the simplex and model in isometric log-ratio (ilr) coordinates. The model in the simplex is based on matrix product, which can project a-part composition to another-part composition, and can deal with different number of parts of compositional variables. Some theorems are given to point out the relationship of parameters between the proposed models. Moreover, the inference for parameters in proposed models is also given. Real example is studied to verify the validity and usefulness of proposed models. [ABSTRACT FROM AUTHOR]

We study the exact controllability of q uncoupled damped string equations by means of the same control function. This property is called simultaneous controllability. An observability inequality is proved, which implies the simultaneous controllability of the system. Our results generalize the previous results on the linear wave without the dampings. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: A -hypertournament on vertices, where , is a pair , where is the vertex set of and is a set of -tuples of vertices, called arcs, such that, for all subsets with , contains exactly one permutation of as an arc. Gutin and Yeo (1997) showed in [2] that any strong -hypertournament on vertices, where , is Hamiltonian, and posed the question as to whether the result could be extended to vertex-pancyclicity. As a response, Petrovic and Thomassen (2006) in [4] and Yang (2009) in [6] gave some sufficient conditions for a strong hypertournament to be vertex-pancyclic. In this paper, we prove that, if is a strong -hypertournament on vertices, where , then is vertex-pancyclic. This extends the aforementioned results and Moon’s theorem for tournaments. Furthermore, our result is best possible in the sense that the bound is tight. [Copyright &y& Elsevier]

Yao et al. (Discrete Appl Math 99 (2000), 245-249) proved that every strong tournament contains a vertex u such that every out-arc of u is pancyclic and conjectured that every k-strong tournament contains k such vertices. At present, it is known that this conjecture is true for k = 1, 2, 3 and not true for k⩾4. In this article, we obtain a sufficient and necessary condition for a 4-strong tournament to contain exactly three out-arc pancyclic vertices, which shows that a 4-strong tournament contains at least four out-arc pancyclic vertices except for a given class of tournaments. Furthermore, our proof yields a polynomial algorithm to decide if a 4-strong tournament has exactly three out-arc pancyclic vertices. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we solve the following combinatorial problem. Let be given sets and be -sets. We lower bound the number of sets such that and, for each , the set does not contain two distinct elements and with , and . Our result directly implies the theorems proved by Bessy et al. [S. Bessy, N. Lichiardopol, J.-S. Sereni, Two proofs of the Bermond–Thomassen conjecture for tournaments with bounded minimum in-degree, Discrete Math. 310 (3) (2010) 557–560]. [Copyright &y& Elsevier]

Abstract: In this paper, we consider a nonlinear viscoelastic wave equation with nonlinear boundary damping and source terms. Under some appropriate assumptions on the relaxation function and with certain initial data, the global existence of solutions and a general decay for the energy have been established. [Copyright &y& Elsevier]