Forecasting of global horizontal irradiance by exponential smoothing, using decompositions

Time series methods are frequently used in solar irradiance forecasting when two dimensional cloud information provided by satellite or sky camera is unavailable. ETS (exponential smoothing) has received extensive attention in the recent years since the invention of its state space formulation. In this work, we combine these models with knowledge based heuristic time series decomposition methods to improve the forecasting accuracy and computational efficiency.<p></p> In particular, three decomposition methods are proposed. The first method implements an additive seasonal-trend decomposition as a preprocessing technique prior to ETS. This can reduce the state space thus improve the computational efficiency. The second method decomposes the GHI (global horizontal irradiance) time series into a direct component and a diffuse component. These two components are used as forecasting model inputs separately; and their corresponding results are recombined via the closure equation to obtain the GHI forecasts. In the third method, the time series of the cloud cover index is considered. ETS is applied to the cloud cover time series to obtain the cloud cover forecast thus the forecast GHI through polynomial regressions. The results show that the third method performs the best among three methods and all proposed methods outperform the persistence models.<p></p&gt

The Heterogeneous Impact of Pension Income on Elderly Living Arrangements: Evidence from China's New Rural Pension Scheme

This paper investigates the impact of pension income on living arrangements of the elderly. Taking advantage of a unique opportunity due to the recent establishment and expansion of the social pension system in rural China, we explicitly address the endogeneity of pension status and income through a fixed-effect model with instrumental variable approach by exploiting exogenous time variation in the program implementation at county level. We find an overall positive effect of pension income on independent living as well as considerable heterogeneity. The elderly with easy access to their adult children, possessing higher financial capacity, in less long-term care and psychological need, and having more education are more likely to live independently after receiving pension income. Our results confirm that independent living is a normal good, but highlight that living arrangement is multidimensional in rural China

The Health Implications of Social Pensions: Evidence from China's New Rural Pension Scheme

This paper estimates the causal effect of income on health outcomes of the elderly and investigates underlying mechanisms by exploiting an income change induced by the launch of China's New Rural Pension scheme (NRPS). Using this policy experiment, we address the endogeneity of pension income by applying a fixed-effect model with instrumental variable correction. The results reveal that pension enrollment and income from the NRPS both have had a beneficial impact on objective measures of physical health, cognitive function, and psychological well-being of the rural elderly, and also reduced mortality over a three-year horizon by 6 percentage points. Evidence further suggests that pension recipients respond to the new pension income in multiple ways: improved nutrition intake, better accessibility to health care, increased informal care, increased leisure activities, and better self-perceived relative economic situation. These in turn act as channels from pension income to health of the Chinese rural elderly

The Heterogeneous Impact of Pension Income on Elderly Living Arrangements: Evidence from China’s New Rural Pension Scheme

This paper investigates the impact of pension income on living arrangements of the elderly. Taking advantage of a unique opportunity due to the recent establishment and expansion of the New Rural Pension Scheme in China, we explicitly address the endogeneity of pension status and pension income through a fixed-effect model with instrumental variable approach by exploiting exogenous time variation in the program implementation at county level. We find an overall positive effect of pension income on independent living as well as considerable heterogeneity. The positive income effects of the NRPS are concentrated among the elderly with adult children living nearby, of higher socio-economic status, and with better health at baseline; for other groups, the effects are insignificant. We also find that more generous programs exhibit larger effects. Our results highlight that living arrangement is multidimensional in rural China

Numerical simulation for machining S-tube by abrasive flow with various particle volume fractions

Abrasive flow machining has become an economical and efficient ultra-precision process for machining complex-shaped pipe parts, and processing effect is exceedingly subject to particle volume fraction. In this paper, aiming at uncovering the influence of various particle volume fractions on the machining result of abrasive flow finishing, based on fluid mechanics theory, mixed phase model and discrete phase model were conducted, FLUENT software was resorted to simulate the numerical characteristics of the solid-liquid two-phase flow field in the inner channel of S-tube with different-particle-volume-fraction abrasive flows, the mechanism of erosion and wear of particles was uncovered, which provides a theoretical basis for abrasive flow machining S-tube structured components

Random lasing action from PMMA waveguide doped with CdSe/ZnS CQDs plasmonically enhanced by Ag nanoislands

In this letter, the random laser is fabricated by an active waveguide structure constructed by covering the layer of poly methyl methacrylate (PMMA) doped CdSe/ZnS colloidal quantum dots (CQDs) onto the Ag nanoisland structures. There is a low threshold due to the excellent overlap of the plasmonic resonance of the Ag nanoislands with the photoluminescence spectrum of the CQDs and the strong confinement mechanism provided by the active waveguide layer. The performances of random laser can be tuned through the flexible fabrication of Ag nanoisland structures. The spectral evolution shows a stability of random lasing under uninterrupted laser irradiation owing to the super chemical and photo stability of CdSe/ZnS CQDs and the stable external environment for CdSe/ZnS CQDs provided by the PMMA matrix.National Natural Science Foundation of China Grant n. 11174160, Grant n. 11474052 and Grant n. 11274062. Jiangsu Overseas Visiting Scholar Program for University Prominent Young & Middle-Aged Teachers and Presidents under N. 2018001