Suchergebnisse

The Chinese government has made many efforts to mitigate fine particulate matter pollution in recent years by taking strict measures on air pollutant reduction, which has generated the nationwide improvements in air quality since 2013. However, under the stringent air pollution controls, how the wintertime PM 2.5 concentration (i.e., the mass concentration of atmospheric particles with diameters less than 2.5 µ m) varies and how much the meteorological conditions contribute to the interannual variations in PM 2.5 concentrations are still unclear, and these very important for the local government to assess the emission reduction of the previous year and adjust mitigation strategies for the next year. The effects of atmospheric circulation on the interannual variation in wintertime PM 2.5 concentrations over the Beijing–Tianjin–Hebei (BTH) region in the period of 2013–2018 are evaluated in this study. Generally, the transport of clean and dry air masses and an unstable boundary layer in combination with the effective near-surface horizontal divergence or pumping action at the top of the boundary layer benefits the horizontal or vertical diffusion of surface air pollutants. Instead, the co-occurrence of a stable boundary layer, frequent air stagnation, positive water vapor advection and deep near-surface horizontal convergence exacerbate the wintertime air pollution. Favorable circulation conditions lasting for 2–4 d are beneficial for the diffusion of air pollutants, and 3–7 d of unfavorable circulation events exacerbates the accumulation of air pollutants. The occurrence frequency of favorable circulation events is consistent with the interannual variation in seasonal mean PM 2.5 concentrations. There is better diffusion ability in the winters of 2014 and 2017 than in other years. A 59.9 % observed decrease in PM 2.5 concentrations in 2017 over the BTH region could be attributed to the improvement in atmospheric diffusion conditions. It is essential to exclude the contribution of meteorological conditions to the variation in interannual air pollutants when making a quantitative evaluation of emission reduction measurements.

The Chinese government has made many efforts to mitigate fine particulate matter (PM 2.5 ) pollution in recent years by taking strict measures on air pollutants reduction, which has generated the nationwide improvements in air quality since 2013. However, under the stringent air pollution controls, how PM 2.5 concentration varies and how much the meteorological conditions contribute to the interannual variations in PM 2.5 concentrations are still unclear, which is very important for the local government to assess the emission reduction of previous year and adjust mitigation strategies of next year. The effects of atmospheric circulation on the interannual variation in wintertime PM 2.5 concentrations over the Beijing-Tianjin-Hebei (BTH) region in the period of 2013–2018 are evaluated in this study. Generally, the transport of clean and dry air masses and unstable boundary layer working with the effective near-surface horizontal divergence or pumping action at the top of the boundary layer benefit for the horizontal or vertical diffusion of surface air pollutants. Instead, the co-occurrence of a stable boundary layer, frequent air stagnation, positive water vapor advection and deep near-surface horizontal convergence exacerbate the air pollution. Favorable circulation conditions lasting for 2~4 days are beneficial for the diffusion of air pollutants, and 3~7 days of unfavorable circulation events exacerbate the accumulation of air pollutants. The occurrence frequency of favorable circulation events is consistent with the interannual variation in seasonal mean PM 2.5 concentrations. There is better diffusion ability in the winters of 2014 and 2017 than in other years. A 76.5 % of the observed decrease in PM 2.5 concentrations in 2017 over the BTH region could be attributed to the improvement in atmospheric diffusion conditions. It is essential to exclude the contribution of meteorological conditions to the variation in interannual air pollutants when making a quantitative evaluation of emission reduction measurements.

The Chinese government has made many efforts to mitigate fine particulate matter pollution in recent years by taking strict measures on air pollutant reduction, which has generated the nationwide improvements in air quality since 2013. However, under the stringent air pollution controls, how the wintertime PM2.5 concentration (i.e., the mass concentration of atmospheric particles with diameters less than 2.5 µm) varies and how much the meteorological conditions contribute to the interannual variations in PM2.5 concentrations are still unclear, and these very important for the local government to assess the emission reduction of the previous year and adjust mitigation strategies for the next year. The effects of atmospheric circulation on the interannual variation in wintertime PM2.5 concentrations over the Beijing–Tianjin–Hebei (BTH) region in the period of 2013–2018 are evaluated in this study. Generally, the transport of clean and dry air masses and an unstable boundary layer in combination with the effective near-surface horizontal divergence or pumping action at the top of the boundary layer benefits the horizontal or vertical diffusion of surface air pollutants. Instead, the co-occurrence of a stable boundary layer, frequent air stagnation, positive water vapor advection and deep near-surface horizontal convergence exacerbate the wintertime air pollution. Favorable circulation conditions lasting for 2–4 d are beneficial for the diffusion of air pollutants, and 3–7 d of unfavorable circulation events exacerbates the accumulation of air pollutants. The occurrence frequency of favorable circulation events is consistent with the interannual variation in seasonal mean PM2.5 concentrations. There is better diffusion ability in the winters of 2014 and 2017 than in other years. A 59.9 % observed decrease in PM2.5 concentrations in 2017 over the BTH region could be attributed to the improvement in atmospheric diffusion conditions. It is essential to exclude the contribution of meteorological conditions to the variation in interannual air pollutants when making a quantitative evaluation of emission reduction measurements.

PurposeHow to determine the appropriate contractual structure for an outsourcing relationship has been a major theme in the business process outsourcing (BPO) literature. Drawing on transaction cost economics, this study aims to examine how anticipated coordination and adaptation costs in a BPO relationship affect the choice of contract types. Specifically, this research categorizes contracts types (fixed-price, time and materials and hybrid contracts) based on levels of contract design comprehensiveness and flexibility to change.Design/methodology/approachThe research setting is the BPO for a focal firm, involving a contractor. Data from 153 US companies are collected using a structured questionnaire on senior executives of functional areas of marketing, IT and finance. Hypotheses were tested using ordered probit model.FindingsThe results show that maturity is negatively associated with anticipated adaptation costs, while modularity and IT detachability are negatively related to anticipated coordination costs. Furthermore, adaptation costs have a direct impact on the choice, whereas the anticipated coordination costs do not have a significant direct impact on contract choice. The strength of adaptation costs' impact, however, is significantly reduced when coordination costs are high.Originality/valueThis study explicitly examines the role of anticipated coordination and adaptation costs in shaping the strategic choice of contract types in the BPO market. By differentiating the two types of anticipated transaction costs, this research enables a better understanding of the dynamics between transaction characteristics, anticipated transaction costs and contract types in complicated relationships such as BPO relationships.

Purpose
Leveraging boundary theory and person–environment fit theory, the purpose of this paper is to propose a model that illustrates the process by which nonwork-related information and communication technologies (ICTs) usage during office hours affects family-to-work conflict (FWC) and work–family balance satisfaction (WFBS), and the moderating effect of family–work segmentation preference (FWSP) in that process.


Design/methodology/approach
Analyses using PROCESS were conducted to analyze the proposed relationships on survey-collected data.


Findings
Augmented ICTs usage led to greater perceptions of FWC, though the strength of this association was contingent on FWSP in that integration preference buffered ICTs usage's detrimental effects. Moreover, ICTs usage was shown to exert an effect on WFBS through FWC. The results indicated a mediated moderation pattern such that the moderating role of ICTs usage and FWSP on WFBS was mediated by FWC.


Originality/value
By focusing on ICTs usage for family reasons at work, the study filled a formerly acknowledged gap in the research field regarding how nonwork-related ICTs usage at work affected work–life balance.

Since digital communication signals are widely used in radio and underwater acoustic systems, the modulation classification of these signals has become increasingly significant in various military and civilian applications. However, due to the adverse channel transmission characteristics and low signal to noise ratio (SNR), the modulation classification of communication signals is extremely challenging. In this paper, a novel method for automatic modulation classification of digital communication signals using a support vector machine (SVM) based on hybrid features, cyclostationary, and information entropy is proposed. In this proposed method, by combining the theory of the cyclostationary and entropy, based on the existing signal features, we propose three other new features to assist the classification of digital communication signals, which are the maximum value of the normalized cyclic spectrum when the cyclic frequency is not zero, the Shannon entropy of the cyclic spectrum, and Renyi entropy of the cyclic spectrum respectively. Because these new features do not require any prior information and have a strong anti-noise ability, they are very suitable for the identification of communication signals. Finally, a one against one SVM is designed as a classifier. Simulation results show that the proposed method outperforms the existing methods in terms of classification performance and noise tolerance.