Institutional Insecurity

Already the world's second biggest energy consumer, China is presently on track to become the world's largest user of energy by the year 2030. This phenomenon has kindled a profusion of literature to address how China will meet this demand and the affect it will have on global energy security. Current analyses overwhelmingly focus on the notion that energy security is based on the assurance of reliable energy supply at a reasonable price, invoking a disproportionate emphasis on the security of China's oil supply. This is largely a result of the psychological elements arising from the uncertainty of guaranteed oil supplies for China. In reality, however, oil imports are merely one dimension of China's energy security concerns and not even the most important. Far less attention has been given to the more obscure though imperative factor of China's domestic energy institutions and their role in meeting the country's energy security challenges both at home and abroad

The globalization of Chinese energy companies

This repository item contains a report from the Boston University Global Economic Governance Initiative. The Global Economic Governance Initiative (GEGI) is a research program of the Center for Finance, Law & Policy, the Frederick S. Pardee Center for the Study of the Longer-Range Future, and the Frederick S. Pardee School of Global Studies. It was founded in 2008 to advance policy-relevant knowledge about governance for financial stability, human development, and the environment

Experimental and computational study of turbulent mixing in a confined rectangular jet

Vortex behavior and characteristics in a confined rectangular jet with a co-flow were examined using vortex swirling strength as a defining characteristic. On the left side of the jet, the positively (counterclockwise) rotating vortices are dominant, while negatively rotating vortices are dominant on the right side of the jet. The characteristics of vortices, such as population density, average size and strength, and deviation velocity were calculated and analyzed in both the cross-stream direction and the streamwise direction. In the near-field of the jet, the population density, average size and strength of the dominant direction vortices show high values on both sides of the center stream with a small number of counter-rotating vortices produced in the small wake regions close to jet outlet. As the flow develops, the wake regions disappear, these count-rotating vortices also disappear, and the population of the dominant direction vortices increase and spread in the jet. The mean size and strength of the vortices decrease monotonically with streamwise coordinate. The signs of vortex deviation velocity indicate the vortices transfer low momentum to high velocity region and high momentum to the low velocity region. The developing trends of these characteristics were also identified by tracing vortices using time-resolved PIV data. Both the mean tracked vortex strength and size decrease with increasing downstream distance overall. At the locations of the left peak of turbulent kinetic energy, the two point spatial cross-correlation of swirling strength with velocity fluctuation and concentration fluctuation were calculated. All the correlation fields contain one positively correlated region and one negatively correlated region although the orientations of the correlation fields varied, due to the flow transitioning from wake, to jet, to channel flow. Finally, linear stochastic estimation was used to calculate conditional structures. The large-scale structures in the velocity field revealed by linear stochastic estimation are spindle-shaped with a titling stream-wise major axis. Vortex behavior and characteristics in a confined rectangular wake were also examined using swirling strength as a defining characteristic of a vortex. Instantaneous swirling strength field shows that positively (counterclockwise) rotating vortices are dominant on the right side of the wake and negatively (clockwise) rotating vortices are dominant on the left side. The population density, average size and strength of vortex cores all shows high peak values both sides of the wakes, while these peaks decrease quickly and the profiles broaden as the flow progresses downstream. The changing of vortex core maximum strength is seen relatively faster than the change of the core size. The results of mean cross-stream wise deviation velocity of vortex core shows the vortices in the wake spread from the neighborhood of wake to the centers of the free stream, and the mean streamwise deviation velocity indicates that vortices bringing high momentum fluid of the free stream into the the wake. Two point spatial cross-correlations of swirling strength with velocity fluctuations and concentration fluctuations were also calculated. All the cross correlation fields shown here exhibit a ``butterfly\u27\u27 like shape, with one ``wing\u27\u27 with positive correlation values and the other ``wing\u27\u27 with negative values. The axises of correlation fields are oriented in the streamwise direction in R λ u\u27 contours, and they tile towards the wake center on the both sides of the wake,while the axises in R λ v\u27 are oriented in the cross-stream direction, and they tile downstream on the both sides of the wake. The R λ phi\u27 results show some similarity to those of R λ v\u27, indicating the vortices play a similar role in mass transfer as in momentum transfer. Linear stochastic estimation was used to interpret the cross correlation result and visualize the underlining large scale coherent structures. The LSE results show a clear vortex street pattern in far fields of the wake, indicating the vortices, developed independently on both sides of the splitter plates, are reorganized and coherent as the flow develops downstream. Large-eddy simulations (LES) were performed for a confined rectangular liquid jet with a co-flow and compared in detail with particle image velocimetry (PIV) measurements. A finite-volume CFD library, OpenFOAM, was used to discretize and solve the filtered Navier-Stokes equation. The effects of grid resolution, numerical schemes and subgrid models on the LES results were investigated. Grid independence has been shown. The second and fourth order schemes showed the nearly same performance, while the fourth order scheme costs much more computationally. Subgrid model comparison showed that the locally dynamic procedure is necessary for complex flow simulation. Model validation was performed by comparing LES data for the one-point velocity statistics such as the mean and the root-mean-square velocity, shear stress, correlation coefficient, velocity skewness and flatness with the PIV data. In addition, LES data for the two-point spatial correlations of velocity fluctuations that provide structural information were computed and compared with PIV data. Very good agreement was obtained leading to the conclusion that the LES velocity field captures the large-scale structures present in the actual flow. Experimental data of combined particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) measurements are used to analyzed the flow between the two scalar interfaces of confined turbulent jet and wake flow. The fluid of center stream of both flow cases contains a fluorescent dye, and normalized PLIF images were used to discriminate the inner and outer boundaries of the center stream. The growth of the boundaries of both flow cases are plotted and analyzed. The mean and fluctuations of the passive scalar, velocity, stain rate, and vorticity are determined relative to the locations of the two boundaries. The results show some unique perspectives of this co-flowing confined rectangular jet flow. The fluctuations of the passive scalar shows high values close to the outer boundary of jet , and the most of the properties of the velocity fields show high values on the left side of inner boundaries of the jet. The results of wake case are very symmetrical about the center of the wake, indicating the presence of the vortex street

Thermal Field Investigations and Applications to Integral Abutment Bridges with FRP Panels

Expansion joints are often considered as one of the most vulnerable elements affecting the sustainability of traditional jointed bridges. Over the past several decades, a new type of integral abutment bridge (IAB) has been proposed, where the joints are eliminated at the abutments and/or along the length of the bridges. Although with wide acceptances, the IABs have not been largely applied in practice. Many arguments are unsettled and there are no national design guidelines currently. Among all, the thermal behavior is one of the most concerned issues, and that, to a large extent, limits the maximum length of IABs that can be constructed. Under this circumstance, a new type of fiber reinforced polymer (FRP) materials, with special material properties, are considered as an alternative to replace the traditional concrete and steel materials. However, the studies on the performances of both IABs and FRP bridges are not adequate. Therefore, an investigation on the thermal behaviors of IABs and FRP bridges is conducted. Then, an effort is made to analyze the responses by combining the FRPs with IABs, and to verify that such a configuration will help resolve the thermal issues of IABs. For FRP bridges, (1) the temperature distributions of a GFRP panel are discussed based on a field monitoring program conducted at the state of Kansas; (2) the influencing factors on the temperature distributions are studied, including the material property, environmental condition, and section hollowness; (3) the thermal gradients of the FRP panel bridges are proposed referring to the AASHTO LRFD design code; and (4) the jointed bridges’ performances, after replacing traditional slabs by FRP panels, are numerically analyzed. For IABs, (1) the thermal responses of the first full IAB in the state of Louisiana, Caminada Bay Bridge, are discussed based on a field monitoring program; (2) a parametric study is employed to analyze the effects of different parameters on the thermal performances, including the soil types, bent-pile connections, loading types, and support conditions; and (3) a numerical study is performed to verify the assumption that applying FRP panels on IABs will help resolve the thermal issues of IABs

Collaborative Deep Reinforcement Learning for Joint Object Search

We examine the problem of joint top-down active search of multiple objects under interaction, e.g., person riding a bicycle, cups held by the table, etc.. Such objects under interaction often can provide contextual cues to each other to facilitate more efficient search. By treating each detector as an agent, we present the first collaborative multi-agent deep reinforcement learning algorithm to learn the optimal policy for joint active object localization, which effectively exploits such beneficial contextual information. We learn inter-agent communication through cross connections with gates between the Q-networks, which is facilitated by a novel multi-agent deep Q-learning algorithm with joint exploitation sampling. We verify our proposed method on multiple object detection benchmarks. Not only does our model help to improve the performance of state-of-the-art active localization models, it also reveals interesting co-detection patterns that are intuitively interpretable