TSEXPLAIN: Explaining Aggregated Time Series by Surfacing Evolving Contributors

Aggregated time series are generated effortlessly everywhere, e.g., "total confirmed covid-19 cases since 2019" and "total liquor sales over time." Understanding "how" and "why" these key performance indicators (KPI) evolve over time is critical to making data-informed decisions. Existing explanation engines focus on explaining one aggregated value or the difference between two relations. However, this falls short of explaining KPIs' continuous changes over time. Motivated by this, we propose TSEXPLAIN, a system that explains aggregated time series by surfacing the underlying evolving top contributors. Under the hood, we leverage prior works on two-relations diff as a building block and formulate a K-Segmentation problem to segment the time series such that each segment after segmentation shares consistent explanations, i.e., contributors. To quantify consistency in each segment, we propose a novel within-segment variance design that is explanation-aware; to derive the optimal K-Segmentation scheme, we develop an efficient dynamic programming algorithm. Experiments on synthetic and real-world datasets show that our explanation-aware segmentation can effectively identify evolving explanations for aggregated time series and outperform explanation-agnostic segmentation. Further, we proposed an optimal selection strategy of K and several optimizations to speed up TSEXPLAIN for interactive user experience, achieving up to 13X efficiency improvement.Comment: 17 pages; Accepted by ICDE 202

Poly(ether block amide)-based Composite Membranes for Carbon Capture

A great amount of anthropogenic CO2 emissions has caused the greenhouse effect which impacts the living environment of creatures on the planet. Effective carbon capture technologies need to be developed to reduce CO2 emissions. Membrane separation technology can be applied in carbon capture due to its advantages in energy conservation and pollution prevention. Poly(ether block amide)-based (PEBAX 1657) composite membranes were developed for carbon capture in separating CO2/N2, CO2/CH4, and CO2/H2 mixtures in this study. Polyvinylamine/PEBAX (PVAm/PEBAX) blend membranes were prepared for carbon capture by a solution casting method. The presence of PVAm enhanced membrane hydrophilicity and gas solubility. When the mass ratio of PVAm to PEBAX reached 0.025, the blend membrane showed a CO2 permeability of 600 Barrer at 298 K and a feed gas pressure of 400 kPa, while the CO2/N2, CO2/CH4, and CO2/H2 ideal gas selectivity remained comparable with pristine PEBAX membrane. Diethanolamine/PVAm/PEBAX (DEA/PVAm/PEBAX) composite membranes were fabricated on polysulfone substrate membranes. The structures of the composite membranes not only improved gas permeance due to reducing the thickness of the permselective layer but also provided great mechanical strength. DEA can increase membrane hydrophilicity. The DEA/PVAm/PEBAX composite membrane with a mass fraction of DEA in the membrane of 0.2 exhibited a CO2 permeance of 12.5 GPU which was higher than the PEBAX composite membrane (6.24 GPU). The CO2/N2, CO2/CH4, and CO2/H2 selectivity was 42.3, 22.9, and 12.1 at room temperature and 700 kPa. NH4F/PEBAX membranes were developed by a solution casting method. The introduction of F- affected the permeabilities of N2, CH4, and H2 in the membranes more significantly than CO2 permeability due to the salting-out effect. On the other hand, F- made water molecules more basic owing to the hydrogen bonds, which was more favorable for CO2 dissolution in the membranes. Compared to pristine PEBAX membrane, the selectivities CO2/N2, CO2/CH4, and CO2/H2 in the NH4F/PEBAX(0.1) membrane were 54%, 13%, and 22% higher, respectively, and the CO2 permeability was 372 Barrer at room temperature and 700 kPa. Mixed matrix membranes were fabricated by embedding amino-modified multi-walled carbon nanotubes (MWCNTs) as a dispersed phase in a PEBAX polymer matrix. After acid treatment, MWCNTs were modified by polydopamine (PDA) through self-polymerization of dopamine (DA). The catechol groups can react with amine groups on branched polyethylenimine (PEI) by the Michael addition reaction and Schiff base reaction. The addition of MWCNT-PDA-PEI can facilitate CO2 transport and adjust membrane structures. When the mass ratio of MWCNTPDA-PEI to PEBAX was 0.08, the CO2 permeability of the prepared MMM was 2.4-fold of that of the PEBAX membrane, while the selectivities of CO2/N2, CO2/CH4, and CO2/H2 at room temperature and 300 kPa were 107, 26, and 11, respectively

Modeling of precision motion control systems: a relay feedback approach

Ph.DDOCTOR OF PHILOSOPH

Influence of leaders' loneliness on voice-taking : the role of social self-efficacy and performance pressure

This paper attempts to unlock how and when leaders’ loneliness influences their voice-taking behavior in the workplace by integrating the regulatory loop model of loneliness and the affect theory of social exchange. Through collecting a daily diary study of 87 paired leader-follower samples from two electronics industry companies based in Guangzhou, China, this study finds that (1) leaders’ loneliness has a significant negative impact on social self-efficacy and voice-taking behavior; (2) leaders’ social self-efficacy mediates the relationship between their loneliness and voice-taking behavior; (3) performance pressure moderates the relationship between leaders’ loneliness and voice-taking behavior; and, (4) the indirect effect between leaders’ loneliness and voice-taking behavior (through social self-efficacy) becomes stronger when performance pressure is higher. Therefore, this study provides some practical implications on: (1) how to provide a series of loneliness interventions to address loneliness in all areas of life; and, (2) how to establish an internal culture or atmosphere within the organization to encourage leaders to adopt followers’ suggestions for improvement

A Conceptual Model to Optimize Operating Cost of Passenger Ships in Macau

To facilitate more convenient travel as the economy of Macau expands, the government of Macau has allowed shipping companies to add passenger ships and shipping lines. This paper demonstrates how shipping companies can reduce costs by optimizing passenger ships and crew size. It analyzes operating conditions for each shipping depot, including transit time, ships, and volume of passengers. A series of integer programming models is proposed. After a practical demonstration using Excel to solve the LP model, we show that the reduction in the number of passenger ships and crew size could reach 22.6% and 29.4%, respectively

Spiritual Leadership on Proactive Workplace Behavior: The Role of Organizational Identification and Psychological Safety

This study investigates whether and why spiritual leadership may contribute to enhanced proactive employee workplace behavior. Based on self-determination theory (SDT), we examine the effects of two sequential mediators (i.e., organizational identification and psychological safety) on the relationship between spiritual leadership and proactive workplace behavior. Data collected from 188 subordinate-leader dyads in Chinese firms suggested that spiritual leadership has a significant positive effect on proactive workplace behavior. In addition, both organizational identification and psychological safety mediate the relationship between spiritual leadership and proactive workplace behavior. Furthermore, spiritual leadership positively influences organizational identification, and such identification nurtures psychological safety, which, in turn, fosters the proactive behavior of employees. It extends the existing impact of spiritual leadership to proactive workplace behavior and shed lights on the mediating mechanisms through which spiritual leadership exerts influences on proactive workplace behavior. Finally, it considers the important roles played by leaders in modern organizations

Age at menarche and risk of major cardiovascular diseases: Evidence of birth cohort effects from a prospective study of 300,000 Chinese women

AbstractBackgroundPrevious studies of mostly Western women have reported inconsistent findings on the association between age at menarche and risk of cardiovascular disease (CVD). Little is known about the association in China where there has been a large intergenerational decrease in women's mean age at menarche.MethodsThe China Kadoorie Biobank recruited 302,632 women aged 30–79 (mean 50.5)years in 2004–8 from 10 diverse regional sites across China. During 7years follow-up, 14,111 incident cases of stroke, 14,093 of coronary heart disease (CHD), and 3200 CVD deaths were reported among 281,491 women who had no prior history of CVD at baseline. Cox regression yielded adjusted hazard ratios (HRs) relating age at menarche to CVD risks.ResultsThe mean (SD) age of menarche was 15.4 (1.9)years, decreasing from 16.2 (2.0) among women born before 1940 to 14.7 (1.6) for those born during the 1960s–1970s. The patterns of association between age at menarche and CVD risk appeared to differ between different birth cohorts, with null associations in older generations but U-shaped or weak positive associations in younger women, especially those born after the 1960s. After minimizing the potential confounding effects from major CVD risk factors, both early and late menarche, compared with menarche at age 13years, were associated with increased risk of CVD morbidity and mortality, which was more pronounced in younger generations.ConclusionAmong Chinese women the associations between age at menarche and risk of CVD differed by birth cohort, suggesting other factors may underpin the association

Exhaled carbon monoxide and its associations with smoking, indoor household air pollution and chronic respiratory diseases among 512 000 Chinese adults

Background Exhaled carbon monoxide (COex) level is positively associated with tobacco smoking and exposure to smoke from biomass/coal burning. Relatively little is known about its determinants in China despite the population having a high prevalence of smoking and use of biomass/coal. Methods The China Kadoorie Biobank includes 512 000 participants aged 30-79 years recruited from 10 diverse regions. We used linear regression and logistic regression methods to assess the associations of COex level with smoking, exposures to indoor household air pollution and prevalent chronic respiratory conditions among never smokers, both overall and by seasons, regions and smoking status. Results The overall COex level (ppm) was much higher in current smokers than in never smokers (men: 11.5 vs 3.7; women: 9.3 vs 3.2). Among current smokers, it was higher among those who smoked more and inhaled more deeply. Among never smokers, mean COex was positively associated with levels of exposures to passive smoking and to biomass/coal burning, especially in rural areas and during winter. The odds ratios (OR) and 95% confidence interval (CI) of air flow obstruction (FEV 1 /FVC ratio <0.7) for never smokers with COex at 7-14 and 514 ppm, compared with those having COex <7, were 1.38 (1.31-1.45) and 1.65 (1.52-1.80), respectively (P trend <0.001). Prevalence of other self-reported chronic respiratory conditions was also higher among people with elevated COex (P <0.05). This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. Conclusion In adult Chinese, COex can be used as a biomarker for assessing current smoking and overall exposure to indoor household air pollution in combination with questionnaires