Ecological Footprint accounting quantifies the supply and demand of Earth’s biocapacity. The National Footprint Accounts (NFA) are the most widely used Ecological Footprint (EF) dataset, and provide results for most countries and the world from 1961 to 2014, based primarily on publicly available UN datasets. Here, we review the evolution of the NFA, describe and quantify the effects of improvements that have been implemented into the accounts since the 2012 edition, and review the latest global trends. Comparing results over six editions of NFAs, we find that time-series trends in world results remain stable, and that the world Ecological Footprint for the latest common year (2008) has increased six percent after four major accounting improvements and more than thirty minor improvements. The latest results from the NFA 2018 Edition for the year 2014 indicate that humanity’s Ecological Footprint is 1.7 Earths, and that global ecological overshoot continues to grow. While improved management practices and increased agricultural yields have assisted in a steady increase of Earth’s biocapacity since 1961, humanity’s Ecological Footprint continues to increase at a faster pace than global biocapacity, particularly in Asia, where the total and per capita Ecological Footprint are increasing faster than all other regions.

Decreasing the crystal growth time and increasing the number of nuclei produced high quality perovskite films toward large-area high-efficiency perovskite solar cells.

The graphics processing unit (GPU) has emerged as a computational accelerator that dramatically reduces the time to discovery in high-end computing (HEC). However, while today's state-of-the-art GPU can easily reduce the execution time of a parallel code by many orders of magnitude, it arguably comes at the expense of significant power and energy consumption. For example, the NVIDIA GTX 280 video card is rated at 236 watts, which is as much as the rest of a compute node, thus requiring a 500-W power supply. As a consequence, the GPU has been viewed as a "nongreen" computing solution.This paper seeks to characterize, and perhaps debunk, the notion of a "power-hungry GPU" via an empirical study of the performance, power, and energy characteristics of GPUs for scientific computing. Specifically, we take an important biological code that runs in a traditional CPU environment and transform and map it to a hybrid CPU+GPU environment. The end result is that our hybrid CPU+GPU environment, hereafter referred to simply as GPU environment, delivers an energy-delay product that is multiple orders of magnitude better than a traditional CPU environment, whether unicore or multicore.

Formal equivalence checking and design debugging / by Shi-Yu Huang and Kwang-Ting (Tim) Cheng p.cm. Includes bibliographical references and index.

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Abstract

The efficiencies of organic-inorganic lead halide perovskite solar cells (PSCs) have significantly increased so far, but the long-term stability of PSCs needs to be urgently improved. In this work, a novel and convenient strategy is developed to improve PSCs' stability by introducing thiourea into perovskite. Thiourea passivates perovskite by the formation of the Pb─S bond on the outermost layer of perovskite and lath-shaped grain among perovskites, which contributes to the improvement of oxygen, light, thermal stability, and little hysteresis. The mechanism is elucidated by the density functional theory calculation. In addition, the additive of thiourea into perovskite significantly improves the quality of perovskite crystal for the adduct of PbI 2 with thiourea as the Lewis base. Devices of a perovskite film with the thiourea additive achieve high efficiencies of 19.57% and 17.67% for active areas of 0.1 and 1.0 cm 2 , respectively. Most importantly, unencapsulated devices retain 98% and 93% of original efficiencies after two months under air conditions for active areas of 0.1 and 1.0 cm 2 , respectively, showing excellent stability. The present work provides a simple and effective method to improve long-term stability of PSCs.

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