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Cheyletus, including Cheyletus malaccensis and Cheyletus eruditus and other species, is a predatory mite at genus level. Some studies have reported distribution rates of Cheyletus in dust samples, but their results are inconsistent. The aim of this meta analysis was to comprehensively evaluate the distribution rates of Cheyletus in dust samples. Articles concerning the distribution rates of Cheyletus species in dust samples were searched and screened in electronic databases. The pooled distribution rate with 95% confidence interval (95% CI) were calculated. Thirteen articles were included in this meta-analysis. A total of 15 studies reported the rates of Cheyletus in all mites from dust and the pooled rate was 2.62% (95% CI: 2.32%–2.92%). A total of three studies reported the rates of dust samples with Cheyletus in all dust samples and their pooled rate was 19.82% (95% CI: 5.10%–34.54%). Heterogeneities existed within included studies and source of heterogeneities could not be found though subgroup analyses by species, publication year, sample size of all mites were conducted. There is a low rate of Cheyletus in all mites from dust and a low rate of dust samples with Cheyletus in all dust samples. [ABSTRACT FROM AUTHOR]

Enhancing the efficiency of gear systems is of significance to reduce fuel consumption and overall weight. Windage power losses become prevailing in high-speed gear systems, such as aero-engine applications. To avoid the shortages and limitations of commonly used methods (e.g. negative volume in dynamic mesh method and one moving object in sliding meshing method), this paper describes an unstructured overset computational fluid dynamics technology to simulate the airflow pattern in a gearbox and calculate the windage losses. A disk, a spur gear and a helical gear, spinning in the air at rotational speed up to 7200 r/min are studied respectively, the windage power losses obtained by the numerical method show good agreement with experimental data and analytical findings in the open literature. Meanwhile, the associated deceleration torques exerted by pressure and viscous forces on spinning gear surfaces are also determined. Furthermore, the overset method facilitates to estimate the windage losses of a non-meshing gear pair. The results of this paper indicate that the overset method can accurately predict the windage power losses and provide a new route to investigate the flow pattern surrounding the gears. This method can serve as an effective tool for engineering applications in the future. [ABSTRACT FROM AUTHOR]

This paper presents a novel decentralised structural damage detection method based on the Wiener filter. The Wiener filter is customarily used for filtering out the noise that has corrupted a signal, and it is also used for system identification by matching the output of the filter with that of the unknown system. In this study, a damage index based on the mean square error of the Wiener filter is proposed to indicate the damage in structures. The current measurement is the input of the filter and the response of the undamaged structure is the design signal. Another index calculated from the cross correlation responses of neighbouring sensors is used to determine the damage location. An experimental study has been carried out on a reinforced concrete structure. The results show that this method is effective and reliable for structural damage detection and localisation. [ABSTRACT FROM AUTHOR]

The interface between steel bar and concrete plays an important role in retaining the strength of reinforced concrete structures. When the interface is damaged by cracking, de-bonding between the two materials and/or other kinds of damage, significant degradation of the structural performances will occur owing to loss of composite actions. In this study, wave propagation on several steel bars embedded in two concrete plates with different de-bonding scenarios is tested. Piezoelectric actuators and sensors are attached to steel bars for recording input and response signals. This paper uses the wavelet transform combined with the wavelet packet decomposition, component energy and Shannon entropy to analyse the experimental results. The results demonstrate that both damage index and relative entropy are sensitive to the existence of de-bonding damage and change linearly with de-bonding length when there is only a single de-bonding damage, while energy and entropy distribution are largely influenced by the property of the excitation signal. When multiple de-bonding exists, however, both the damage index and relative entropy have no such clear tendency. [ABSTRACT FROM AUTHOR]

We address a multi-category workforce planning problem for functional areas located at different service centres, each having office-space and recruitment capacity constraints, and facing fluctuating and uncertain workforce demand. A deterministic model is initially developed to deal with workforce fluctuations based on an expected demand profile over the horizon. To hedge against the demand uncertainty, we also propose a two-stage stochastic program, in which the first stage makes personnel recruiting and allocation decisions, while the second stage reassigns workforce demand among all units. A Benders' decomposition-based algorithm is designed to solve this two-stage stochastic mixed-integer program. Computational results based on some practical numerical experiments are presented to provide insights on applying the deterministic versus the stochastic programming approach, and to demonstrate the efficacy of the proposed algorithm as compared with directly solving the model using its deterministic equivalent. [ABSTRACT FROM AUTHOR]