Energy management of buildings with energy storage and solar photovoltaic:A diversity in experience approach for deep reinforcement learning agents

Deep reinforcement learning(DRL)is a suitable approach to handle uncertainty in managing the energy consumption of buildings with energy storage systems.Conventionally,DRL agents are trained by randomly selecting samples from a data set,which can result in overexposure to some data categories and under/no exposure to other data categories.Thus,the trained model may be biased towards some data groups and underperform(provide suboptimal results)for data groups to which it was less exposed.To address this issue,diversity in experience-based DRL agent training framework is proposed in this study.This approach ensures the exposure of agents to all types of data.The proposed framework is implemented in two steps.In the first step,raw data are grouped into different clusters using the K-means clustering method.The clustered data is then arranged by stacking the data of one cluster on top of another.In the second step,a selection algorithm is proposed to select data from each cluster to train the DRL agent.The frequency of selection from each cluster is in proportion to the number of data points in that cluster and therefore named the proportional selection method.To analyze the performance of the proposed approach and compare the results with the conventional random selection method,two indices are proposed in this study:the flatness index and the divergence index.The model is trained using different data sets(1-year,3-year,and 5-year)and also with the inclusion of solar photovoltaics.The simulation results confirmed the superior performance of the proposed approach to flatten the building’s load curve by optimally operating the energy storage system.

Tree diversity effects on forest productivity increase through time because of spatial partitioning

Background: Experimental manipulations of tree diversity have often found overyielding in mixed-species plantations. While most experiments are still in the early stages of stand development, the impacts of tree diversity are expected to accumulate over time. Here, I present findings from a 31-year-old tree diversity experiment(as of2018) in Japan.Results: I find that the net diversity effect on stand biomass increased linearly through time. The species mixture achieved 64% greater biomass than the average monoculture biomass 31 years after planting. The complementarity effect was positive and increased exponentially with time. The selection effect was negative and decreased exponentially with time. In the early stages(≤ 3 years), the positive complementarity effect was explained by enhanced growths of early-and mid-successional species in the mixture. Later on(≥ 15 years), it was explained by their increased survival rates owing to vertical spatial partitioning — i.e. alleviation of self-thinning via canopy stratification. The negative selection effect resulted from suppressed growths of late-successional species in the bottom layer.Conclusions: The experiment provides pioneering evidence that the positive impacts of diversity-driven spatial partitioning on forest biomass can accumulate over multiple decades. The results indicate that forest biomass production and carbon sequestration can be enhanced by multispecies afforestation strategies.

CEOs’Diverse Career Experiences and the Effectiveness of Compensation Contracts:Evidence from Compensation Stickiness

CEO compensation stickiness represents an important indicator to measure the effectiveness of compensation contracts.This study uses CEO career experience data and compensation stickiness data from Shanghai and Shenzhen A-share listed companies from 2015 to 2020 to investigate the compensation contracts’effectiveness of CEOs with diverse career experiences.The findings are as follows:1)Compensation stickiness is more pronounced for CEOs with diverse career experiences.According to the mechanism test,these CEOs with diverse career experiences can obtain compensation incentives by reducing corporate uncertainty perception and improving total factor productivity.This approach leads to increased compensation stickiness and the effectiveness of compensation contracts.CEOs with diverse career experiences may receive excess compensation by raising agency costs,which intensifies compensation stickiness and weakens the effectiveness of compensation contracts.2)Compensation stickiness of CEOs with diverse career experiences is more significant in companies with lower investor protection,which brings about less effective compensation contracts.In contrast,in companies with higher diversification,the compensation stickiness of CEOs with diverse career experiences is more significant,which delivers more effective compensation contracts.The conclusions deepen the research of CEO compensation contracts and provide a helpful reference for CEO compensation management practices.

The importance of ecotype diversity on duckweed growth with and without salt stress

The pollution of freshwater ecosystems is threatening freshwater plant species diversity worldwide.Freshwater plants,such as the common duckweed(Lemna minor),are potentially sensitive to novel stressful environments.To test if ecotype diversity could increase resistance to stressful environments,I used seven L.minor populations and measured their growth rates with and without moderate salt stress across an ecotype diversity gradient.The L.minor populations were grown over 5 months in 92 experimental mesocosms,either in ecotype monocultures or in polyculture with either one or three conspecific ecotypes(23 unique compositions).After growing the duckweed in unperturbed conditions(phase 1),the cultures were subjected to moderate salt stress(50 mmol/L NaCl)for several weeks(phase 2).The experiment was conducted in the presence of the natural epimicrobial community associated with the different ecotypes.In phase 2,a subset of these algae added an unintentional second stressor to the experiment.The ecotypes differed in their growth rates,the fastest growing at twice the rate of others.The diversity context further shaped the ecotype growth rates.Ecotype polycultures showed higher abundances towards the end of the experiment,thus over time,as the environment deteriorated,ecotype diversity gained in importance.These findings show that within-species variation in growth rates can translate to a positive effect of ecotype diversity on population abundance.Exposure of L.minor to moderate salt levels did not significantly impact growth rates,although the effect may have been masked by reduced algal stress in the saline environments.