Spatial distribution of cultural ecosystem services demand and supply in urban and suburban areas: a case study from Shanghai, China

In the urban ecosystem, the demand for cultural ecosystem services (CES) has greatly increased, and the imbalance of CES supply and demand has been prominent. This paper integrated multi-source data to analyze and visualize the spatial differences in CES demand and supply capacity between Shanghai urban center and suburbs. Based on the geo-tagged photo data, the spatial distribution differences of the four types of CES demand, Recreation & tourism services (RTS) demand, Aesthetic services (AS) demand, Heritage & cultural services (HCS) demand, and Spiritual & religious services (SRS) demand, were analyzed. Residents and tourists had a strong demand for recreation and tourism, and the spatial agglomeration effect was the most obvious. Overall, CES demand was more concentrated in urban center, while the spatial distribution of suburbs was relatively discrete. At the same time, there were under supply areas of CES near the Huangpu River in urban center and suburbs. Results from bivariate Moran's I method showed: 1) there was a significant positive spatial correlation between CES demand and CES supply capacity in urban center; 2) CES supply had a positive external impact on CES demand; and 3) the increase in CES supply capacity can promote the growth of CES demand

Ultra-compact lithium niobate photonic chip for high-capacity and energy-efficient wavelength-division-multiplexing transmitters

Recently, high-performance thin-film lithium niobate optical modulators have emerged that, together with advanced multiplexing technologies, are highly expected to satisfy the ever-growing demand for high-capacity optical interconnects utilizing multiple channels. Accordingly, in this study, a compact lithium-niobate-on-insulator (LNOI) photonic chip was adopted to establish four-channel wavelength-division-multiplexing (WDM) transmitters, comprising four optical modulators based on ultracompact 2 × 2 Fabry-Perot cavities and a four-channel WDM filter based on multimode waveguide gratings. The fabricated chip with four wavelength channels has a total footprint as compact as 0.3 × 2.8 mm2, and exhibits an excess loss of ~0.8 dB as well as low inter-channel crosstalk of < –22 dB. Using this LNOI photonic chip, high-capacity data transmissions of 320 Gbps (4 × 80 Gbps) on-off-keying signals and 400 Gbps (4 × 100 Gbps) four-level pulse amplitude signals were successfully realized with the ultra-low power consumption of 11.9 fJ/bit

The Future of the Correlated Electron Problem

The understanding of material systems with strong electron-electron interactions is the central problem in modern condensed matter physics. Despite this, the essential physics of many of these materials is still not understood and we have no overall perspective on their properties. Moreover, we have very little ability to make predictions in this class of systems. In this manuscript we share our personal views of what the major open problems are in correlated electron systems and we discuss some possible routes to make progress in this rich and fascinating field. This manuscript is the result of the vigorous discussions and deliberations that took place at Johns Hopkins University during a three-day workshop January 27, 28, and 29, 2020 that brought together six senior scientists and 46 more junior scientists. Our hope, is that the topics we have presented will provide inspiration for others working in this field and motivation for the idea that significant progress can be made on very hard problems if we focus our collective energies.Comment: 55 pages, 19 figure

Carbon Prices and Fuel Switching: A Quasi-Experiment in Electricity Markets

Within the Pennsylvania-New Jersey-Maryland electricity market, Delaware and Maryland participate in the Regional Greenhouse Gas Initiative (RGGI) but other states do not, providing a quasi-experimental setting to study the RGGI program. Using a difference-in-difference framework, we find that, overall the RGGI program led to 6.22 million short tons of CO2 reduction per year in Delaware and Maryland, or about 19.10% of the average total potential annual emissions in these two states from 2009 to 2013. Counterintuitively however, the reduction is mainly achieved through reduction of coal inputs and emission leakage instead of fuel switching from coal to natural gas or from fossil fuel (coal and natural gas) to non-fossil fuel

Have U.S. Power Plants Become Less Technically Efficient? The Impact of Carbon Emission Regulation

We estimate directional distance functions to measure the impact of carbon emission regulation, the Regional Greenhouse Gas Initiative (RGGI) in particular, on U.S. power plants\u27 technical efficiency. The model shows that the average technical efficiency scores for coal and natural gas plants are 88.70% and 83.14% respectively, indicating a very technically efficient industry. We find no evidence of technical efficiency changes due to the RGGI regime in the RGGI area. In the same area, relatively less efficient coal plants exited the market and slightly more efficient natural gas plants entered, compared to the incumbent plants. In addition, some evidence of a spillover effect is found. Using a counterfactual analysis, the RGGI regulation leads to a 1.48% decline in the average technical efficiency for coal plants within neighboring states of RGGI during 2009-2013

How Regional Policies Reduce Carbon Emissions in Electricity Markets: Fuel Switching or Emission Leakage

There are many concerns that regional carbon programs reduce emissions through emission leakage instead of through fuel switching. We use individual firm-level data to investigate the mechanisms of how the Regional Greenhouse Gas Initiative (RGGI) reduces CO emissions and quantify emission leakage. We find that the RGGI program reduced CO emissions by 13.43% of the total emissions from 2009 to 2017 in the RGGI area, among which only 14.35% of the emissions reduction is due to fuel switching from coal to natural gas. From 43.11% (the lower bound) to 85.65% (the upper bound) of the emissions reduction in the RGGI-regulated states are leaked into unregulated areas. We also find that policy-induced fuel switching and fuel price-induced fuel switching increase natural gas heat percentage (natural gas heat input relative to natural gas and coal heat input) in the regulated area by 2.98% and 5.17%, respectively

The Spatial Distribution, Influencing Factors, and Development Path of Inbound Tourism in China—An Empirical Analysis of Market Segments Based on Travel Motivation

According to China&rsquo;s tourism statistics, the inbound tourism market is composed of eight types of travel motivations (sightseeing, leisure, business meeting (business-m), visiting relatives and friends (visiting-rf), shopping, religious worship (religious-w), culture and sports (culture-s), and health care (health-c)), and the spatial distribution of each type of travel motivation is significantly different. Four inbound sub-markets (foreigners, Hong Kong, Macao, and Taiwan) were selected as our research object. Through empirical analysis of the variable elasticity of eight different inbound motive market segments, we found that the sensitivities (elasticity) of the influencing factors (traffic conditions (traffic-c), destination image (destination-i), industry structure (industry-s), infrastructure, consumer price index (CPI), resource endowment (resource-e), and dressing index (ICL)) are different. Therefore, investment options in the target market can have differential treatment based on the rate of marginal return on investment. In accordance with the characteristics of different market segments, we suggest more feasible development paths and countermeasures, providing a decision-making basis for the accurate development of the inbound tourism market

Deformation and Fracture Failure of a High-Speed Long Rod Intercepted by Linear Explosively Formed Penetrators Sequence

The fracture failure of a high-speed long rod has historically been a challenge. Since the flying plate and flying rod have a relatively low velocity, it is challenging to achieve a multi-stage fracture of the high-speed long rod within the range of existing technology. In this paper, the linear explosively formed penetrators (LEFPs) sequence with a stable flight velocity of 850 m/s were used to cut a high-speed long rod. We investigated the deformation and fracture of &Phi;10 mm tungsten alloy long rods having different length-diameter ratios (20, 26, 35) and different speeds (1200, 1400, 1600 m/s) by employing the LEFPs sequence with different spacings (0&ndash;40 mm) and different interception angles (30&deg;, 60&deg;). In the meantime, the fractured rods movement pattern was recorded with a high-speed camera to elucidate the change law of the length, speed, linear momentum, and angular momentum of fractured rods. It was found that the length loss rate of the fractured rods is as high as 27%. The fractured rods rotated around the center of mass, and the vertical speed change could reach up to 18% of the muzzle velocity of the long rod, and the greatest reduction of horizontal speed and momentum could reach 37%. The longer the interaction time between LEFPs sequence and the long rod, the more beneficial the failure of the long rod. The application of LEFPs sequence solved the difficult problem of disabling the high-speed long rod, and the quantitative analysis of the fracture failure of the long rod had an important sense for studying the terminal penetration effect of the fractured rods