This work presents an ultra-low-power software-defined always-on wake-up system to drastically decrease the system power of Internet of Things (IoTs) devices, which usually operate in random-sparse-event (RSE) scenarios. It mainly thanks to a clock-free time-shielding level-crossing ADC (TS-LCADC), software-defined clock-free multi-function detectors, and an asynchronous pipelined event-driven architecture. First, by quantifying RSE noisy signals with clock-free adaptive sampling in a signal-noise-rejecting manner, the proposed TS-LCADC reduces number of sampling points and power, and consumes only 41 nW when on-call waiting for IoT events. Second, the proposed clock-free multi-function detectors with offline and online programmability are able to character the signal features of versatile IoTs events and allow versatile and dynamic wake-up functions. Third, the proposed asynchronous pipelined event-driven architecture minimizes the system activity and thus power, because a power-hungry high-performance system (HPS) is only woken up when a detected parameter crosses its corresponding threshold. As such, the long-term average power (LTA-power) is dominated by the always-on circuits in RSE scenarios. The measurement results achieve 71–75 nW for three typical applications, i.e., heart rate, epilepsy, and keyword envelope detection. The LTA power is only 57 nW when waiting for RSE events, which is 30 $\times $ lower than a prior general-purpose wake-up chip. Compared with other works of dedicated voice and acoustic wake-up functions, this work consumes 2 $\times $ and 17 $\times $ less power, respectively, while featuring 16 $\times $ higher signal bandwidth and a broader versatility.
Corporate environmental responsibility (CER) is increasingly gaining interest among researchers and practitioners. Despite this extensive interest, systematic research regarding the effect of sales on environmental performance remains scarce. In this study, an empirical analysis on a sample of 909 Chinese listed companies from 2010 to 2016 showed that sales positively impact environmental performance. This study also showed that corporate innovation mediates the relationship between sales and environmental performance. Furthermore, this study showed that environmental performance has a positive spatial spillover effect. Enterprises appear to promote their own environmental performance as a response to a rise in the environmental performance of their neighbors. The external control theory of organization has important reference significance and explanatory power for CER behavior in emerging economies.
Traditional studies of firm performance typically focus on the effect of market structure and rarely consider the impact of the spatiotemporal context in industrial competition.Using a sample of 1,555 listed companies from 2015 to 2018 in China, this study shows that the profit center of gravity tends to move from southeast to northwest, and that there are negative effects on firm performance with distance from the profit center of gravity. Moreover, when controlling for organizational variables, strategic interaction at the local level significantly mediates the relationship between spatiotemporal context at the global level and firm performance at the microlevel. This investigation provides preliminary support for strategic interaction as a significant mediator between spatiotemporal context and firm performance, and further highlights the relevance of spatiotemporal context and strategic interaction in determining firm performance. The results of this study contribute to our understanding of the dynamic mechanism of spatiotemporal context affecting firm performance and the role of strategic interaction at the local level in this relationship, which can improve the existing insights into new economic geography.
Danjiangkou Reservoir is the biggest artificial reservoir in China. But spatiotemporal distribution and risks of metal(loid)s in it were still unclear after the operation of Middle Route of South-to-North Water Diversion Project. In this study, distribution pattern of fifteen metal(loid)s in the Danjiangkou Reservoir was investigated. It was shown that metal(loid)s concentrations in the water were much lower than the drinking water quality standards in China, while Sb, Co, Cd and Cr were identified as the major pollutants in the sediments. Environment-metal(loid)s correlation analysis revealed total organic carbon, sulfate, temperature, dissolved oxygen and total phosphorus markedly controlled metal(loid)s distribution in the water, while organic carbon, total phosphorus and ammonia nitrogen shaped their distribution in the sediments. Results of risk assessment further revealed that the sediments of Danjiangkou Reservoir were minor to moderate polluted, and Sb, Cd exhibited the highest potential ecological risk. Additionally, source identification showed agricultural activities (25.3%), industrial and mining activities (17.5%) and natural processes (57.2%) were the dominant sources of metal(loid)s burden in the sediments. Overall, the results are of significance to understanding the ecological risk and pollution sources in the Danjiangkou Reservoir, which is essential for the effective management of metal(loid)s pollution.
Objective: As elderly parents today will share a longer life with their children than ever before, the spillover effects of children's human capital on parents' wellbeing become increasingly important. This study investigated whether children's schooling leads parents to give up smoking and whether the effects were moderated by their education or child-parent contact frequency. Methods: Using data from the China Health and Retirement Longitudinal Study (CHARLS), we conducted an instrumental variable analysis using China's compulsory schooling reform in the 1980s as a natural experiment. Results: The Instrumental Variable (IV) estimates suggest that elderly parents of more highly educated children are more likely to quit smoking. Moreover, the effects are more significant among parents who had not finished primary school and also slightly stronger among parents who live close to their children or meet their children frequently. Discussion: Our findings add to current evidence on spillover effects of education in smoking cessation. A child's education may exert the impact through the spillover of health knowledge.
We develop a novel approach to explain why AdaBoost is a successful classifier. By introducing a measure of the influence of the noise points (ION) in the training data for the binary classification problem, we prove that there is a strong connection between the IONand the test error.We further identify that the ION of AdaBoost decreases as the iteration number or the complexity of the base learners increases.We confirm that it is impossible to obtain a consistent classifier without deep trees as the base learners of AdaBoost in some complicated situations.We apply AdaBoost in portfolio management via empirical studies in the Chinese market, which corroborates our theoretical propositions.
Recently, a novel retina-inspired camera, namely spike camera, has shown great potential for recording high-speed dynamic scenes. Unlike the conventional digital cameras that compact the visual information within the exposure interval into a single snapshot, the spike camera continuously outputs binary spike streams to record the dynamic scenes, yielding a very high temporal resolution. Most of the existing reconstruction methods for spike camera focus on reconstructing images with the same resolution as spike camera. However, as a trade-off of high temporal resolution, the spatial resolution of spike camera is limited, resulting in inferior details of the reconstruction. To address this issue, we develop a spike camera super-resolution framework, aiming to super resolve high-resolution intensity images from the low-resolution binary spike streams. Due to the relative motion between the camera and the objects to capture, the spikes fired by the same sensor pixel no longer describes the same points in the external scene. In this paper, we properly exploit the relative motion and derive the relationship between light intensity and each spike, so as to recover the external scene with both high temporal and high spatial resolution. Experimental results demonstrate that the proposed method can reconstruct pleasant high-resolution images from low-resolution spike streams.
A novel solar active AgBr/BiOBr/TiO2 catalyst was synthesized by a facile coprecipitation method for solar-driven water remediation. The synthesized material composed of flower-like TiO2 nanoparticles loaded on BiOBr nanosheets and with homogeneous surface distributed Ag/AgBr nanoparticles. The internal electric field between BiOBr/TiO2 heterojunction greatly facilitated the charge carrier migration; the introduction of narrow band gap semiconductors (AgBr and BiOBr) promoted the visible light adsorption; and the Ag/AgBr nanoparticles acted as photosensitizer to further improve the light utilization. The new material showed 7.6- and 4.0-times activity of pure TiO2 and BiOBr under solar light, and the contribution of reactive species on anthracene degradation followed the order of h+ >O2•−> •OH. The degradation mechanism and pathway were proposed based on intermediates analysis and DFT calculation. The QSAR analysis revealed that the environmental risks of contaminants were greatly reduced during the photocatalysis process but some intermediates were still toxic. The high photocatalytic activity, stability and adaptability all indicated that this new material owns great application potential for cost-effective photocatalytic remediation of persistent organic contaminants under solar light.
Abstract Intense and frequent new particle formation (NPF) events have been observed in polluted urban environments, yet the dominant mechanisms are still under debate. To understand the key species and governing processes of NPF in polluted urban environments, we conducted comprehensive measurements in downtown Beijing during January – March 2018. We performed detailed analyses on sulfuric acid cluster composition and budget, as well as the chemical and physical properties of oxidized organic molecules. Our results demonstrate that the fast clustering of sulfuric acid (H2SO4) and base molecules triggered the NPF events, and oxidized organic molecules (OOMs) further helped grow the newly formed particles towards climate- and health-relevant sizes. This synergistic role of H2SO4, base species, and OOMs in NPF is likely representative of polluted urban environments where abundant H2SO4 and base species usually co-exist, and OOMs are with moderately low volatility when produced under high NOx concentrations.