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Persistent eutrophication and hypoxia in the coastal ocean
- Minhan Dai, Yangyang Zhao, Fei Chai, Mingru Chen, Nengwang Chen, Yimin Chen, Danyang Cheng, Jianping Gan, Dabo Guan, Yuanyuan Hong, Jialu Huang, Yanting Lee, Kenneth Mei Yee Leung, Phaik Eem Lim, Senjie Lin, Xin Lin, Xin Liu, Zhiqiang Liu, Ya-Wei Luo, Feifei Meng, Chalermrat Sangmanee, Yuan Shen, Khanittha Uthaipan, Wan Izatul Asma Wan Talaat, Xianhui Sean Wan, Cong Wang, Dazhi Wang, Guizhi Wang, Shanlin Wang, Yanmin Wang, Yuntao Wang, Zhe Wang, Zhixuan Wang, Yanping Xu, Jin-Yu Terence Yang, Yan Yang, Moriaki Yasuhara, Dan Yu, Jianmin Yu, Liuqian Yu, Zengkai Zhang, Zhouling Zhang
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- Journal:
- Cambridge Prisms: Coastal Futures / Volume 1 / 2023
- Published online by Cambridge University Press:
- 23 February 2023, e19
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- Article
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Coastal eutrophication and hypoxia remain a persistent environmental crisis despite the great efforts to reduce nutrient loading and mitigate associated environmental damages. Symptoms of this crisis have appeared to spread rapidly, reaching developing countries in Asia with emergences in Southern America and Africa. The pace of changes and the underlying drivers remain not so clear. To address the gap, we review the up-to-date status and mechanisms of eutrophication and hypoxia in global coastal oceans, upon which we examine the trajectories of changes over the 40 years or longer in six model coastal systems with varying socio-economic development statuses and different levels and histories of eutrophication. Although these coastal systems share common features of eutrophication, site-specific characteristics are also substantial, depending on the regional environmental setting and level of social-economic development along with policy implementation and management. Nevertheless, ecosystem recovery generally needs greater reduction in pressures compared to that initiated degradation and becomes less feasible to achieve past norms with a longer time anthropogenic pressures on the ecosystems. While the qualitative causality between drivers and consequences is well established, quantitative attribution of these drivers to eutrophication and hypoxia remains difficult especially when we consider the social economic drivers because the changes in coastal ecosystems are subject to multiple influences and the cause–effect relationship is often non-linear. Such relationships are further complicated by climate changes that have been accelerating over the past few decades. The knowledge gaps that limit our quantitative and mechanistic understanding of the human-coastal ocean nexus are identified, which is essential for science-based policy making. Recognizing lessons from past management practices, we advocate for a better, more efficient indexing system of coastal eutrophication and an advanced regional earth system modeling framework with optimal modules of human dimensions to facilitate the development and evaluation of effective policy and restoration actions.
Characterization of thermal interface resistance in thermoelectric generators
- C. Ramesh Koripella, Lon E. Bell, Doug Crane, Dazhi Wang
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- Journal:
- MRS Online Proceedings Library Archive / Volume 1325 / 2011
- Published online by Cambridge University Press:
- 13 July 2011, mrss11-1325-e04-09
- Print publication:
- 2011
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Thermoelectric generators are actively being pursued to recover waste heat from the auto exhaust gas to improve vehicle fuel economy. Efficiency of a thermoelectric generator is defined as the ratio of electrical power output to the heat input. In a typical thermoelectric generator, a heat exchanger captures the heat from the medium (ex: hot exhaust gas heat) and this heat needs to be transferred to the hot end of the thermoelectric elements with minimum losses. It is important to understand and minimize these thermal losses to improve the efficiency of a thermoelectric generator. Accurate measurement of the thermal interface resistance parameters is also important because they are used in a comprehensive thermoelectric system model to predict the performance of the generator under actual use conditions. To understand the factors influencing the thermal interface resistance, and to determine the effective thermal interface resistance between the heat exchanger and the thermoelectric hot shunts in a prototype generator that is currently being developed for auto exhaust heat recovery application, we have designed and built a test setup to characterize the thermal interface resistance under high heat flux conditions. Measured temperature profiles in the test sample, heat input into the test device and its geometry are fed into a thermal model to extract the thermal conductance parameters. Factors affecting the thermal interface resistance and the influence of different interface materials were evaluated. Suitable solutions with minimum thermal loss were selected for building the prototype thermoelectric generator for waste heat recovery application and validating the system model.