Nanjing University of Information Science and Technology

About: Nanjing University of Information Science and Technology is a education organization based out in Nanjing, China. It is known for research contribution in the topics: Precipitation & Aerosol. The organization has 14129 authors who have published 17985 publications receiving 267578 citations. The organization is also known as: Nan Xin Da.

How climate change impacted the collapse of the Ming dynasty

Abstract: Based on the reconstructed temperatures, precipitation changes, and occurrences of extreme climate events, together with historical records on fiscal deterioration, food crises, and the frequencies of popular unrest, rebellions and wars, we identified three principal ways in which climate change contributed to the collapse in the Ming dynasty. Firstly, cooling, aridification, and desertification during a cold period destroyed the military farm system, which was the main supply system for the provisioning of government troops on the northern frontiers; these impacts increased the military expenditure from 64 % of total government expenditure in 1548–1569 to 76 % in 1570–1589 and thus aggravated the national fiscal crisis that occurred during the late Ming dynasty. Secondly, climate deterioration (e.g., cooling, aridification, and an increase in the frequencies of frost- and drought-related disasters, etc.) led to a 20–50 % reduction in the per capita production of raw grain in most areas of China, which resulted in widespread food crises and exacerbated the vulnerability of social structures during the last several decades of the Ming dynasty. Thirdly, the severe droughts occurring in 1627–1643 were a key trigger to the peasantry uprising. These droughts also played a significant role to promote the peasantry uprising, especially reviving the peasantry troops by recruitment of famine victims when they nearly perished in 1633 and 1638, and severely disrupting the food supply for the government troops, resulting in the final defeat of the government troops by the peasantry troops. This study contributes to an understanding of the climate-related mechanisms behind the collapse of the Ming dynasty, and provides a historical case study that enhances our understanding of the nature of interactions between climate change and social vulnerability.

The Layer-Wise Training Convolutional Neural Networks Using Local Loss for Sensor-Based Human Activity Recognition

Abstract: Recently, deep learning, which are able to extract automatically features from data, has achieved state-of-the-art performance across a variety of sensor based human activity recognition (HAR) tasks. However, the existing deep neural networks are usually trained with a global loss, and all hidden layer weights have to be always kept in memory before the forward and backward pass has completed. The backward locking phenomenon prevents the reuse of memory, which is a crucial limitation for wearable activity recognition. In the paper, we proposed a layer-wise convolutional neural networks (CNN) with local loss for the use of HAR task. To our knowledge, this paper is the first that uses local loss based CNN for HAR in ubiquitous and wearable computing arena. We performed experiments on five public HAR datasets including UCI HAR dataset, OPPOTUNITY dataset, UniMib-SHAR dataset, PAMAP dataset, and WISDM dataset. The results show that local loss works better than global loss for tested baseline architectures. At no extra cost, the local loss can approach the state-of-the-arts on a variety of HAR datasets, even though the number of parameters was smaller. We believe that the layer-wise CNN with local loss can be used to update the existing deep HAR methods.

Impact of different El Niño types on the El Niño/IOD relationship

Abstract: Previous studies reported that positive phases of the Indian Ocean Dipole (IOD) tend to accompany El Nino during boreal autumn. Here we show that the El Nino/IOD relationship can be better understood when considering the two different El Nino flavors. Eastern-Pacific (EP) El Nino events exhibit a strong correlation with the IOD dependent on their magnitude. In contrast, the relationship between Central-Pacific (CP) El Nino events and the IOD depends mainly on the zonal location of the sea surface temperature anomalies rather than their magnitude. CP El Nino events lying further west than normal are not accompanied by significant anomalous easterlies over the eastern Indian Ocean along the Java/Sumatra coast, which is unfavorable for the local Bjerknes feedback and correspondingly for an IOD development. The El Nino/IOD relationship has experienced substantial changes due to the recent decadal El Nino regime shift, which has important implications for seasonal prediction.

Climate-related flood risks and urban responses in the Pearl River Delta, China

Abstract: Growing concern on climate-related flood hazards has led to increasing interest in understanding the interactions between climate, flood, and human responses. This paper jointly investigates climate change trends, impacts on flood events, flood vulnerability and risk, and response strategies in the Pearl River Delta (PRD), a rapidly urbanizing coastal area in southeast China. Our analysis based on a reanalysis dataset and model projections are integrated with literature results, which indicates a climate scenario of increasing mean temperature, precipitation, sea level, typhoon intensity, and the frequency of extreme weather events in the PRD. These trends, together with the continuing urbanization in flood-prone areas, are expected to increase flood frequency and aggravate both the scale and degree of flooding in the PRD area. We further estimate the flood vulnerability of the 11 PRD cities using the indicator system method. The results suggest that the exposure and sensitivity of central cities (Hong Kong, Macao, Shenzhen, and Guangzhou) are very high because of highly exposed populations and assets located in lowland areas. However, the potential vulnerability and risk can be low due to high adaptive capacities (both by hard and soft flood-control measures). A novel framework on flood responses is proposed to identify vulnerable links and response strategies in different phases of a flood event. It further suggests that the flood risks can be mitigated by developing an integrated climate response strategy, releasing accurate early warning and action guidance, sharing flood-related information, and applying the advantages of online social network analysis.