Polycentric development in China’s mega-city regions, 2001-08: A comparison of the Yangtze and Pearl River Deltas

Large-scale urban regions are increasingly functioning as the territorial backbone of the global economy. Many of these mega-city regions are polycentric in that they consist of a range of densely interwoven cities and towns. The purpose of this chapter is to analyse the geographies of these polycentric networks in what are arguably China’s two most important mega-city regions: the Yangtze River Delta (YRD) and the Pearl River Delta (PRD). To this end, we deployed a methodology that allowed the analysis of the shifting spatial organization of mega-city regions through the lens of the headquarters–branches linkages of corporations; that is, we explored the mega-city regions’ constituent urban networks by looking at the ownership linkages running from a corporation’s headquarters to the corporation’s branches. In the process, this research extended and refined the statistical tools that are often deployed to measure polycentricity. Our results suggest that in both the YRD and the PRD there are more and more linkages interconnecting the mega-city region. The two regions share the following features: the general level of polycentricity is increasing, even though the concentration of headquarters is also increasing; and the growth of the general level of polycentricity mainly originates from higher levels of network density. There are, however, also fundamental differences between the YRD and the PRD: firms in the PRD are more likely to set up branches beyond the prefectures’ boundaries, which results in higher levels of network density than in the YRD; there is a relatively 'flatter' intercity network in the YRD compared to the PRD, in which there are more firms’ links interconnecting the four major cities (Guangzhou, Shenzhen, Dongguan and Foshan), rather than other small and medium-size cities

Probability-based Global Cross-modal Upsampling for Pansharpening

Pansharpening is an essential preprocessing step for remote sensing image processing. Although deep learning (DL) approaches performed well on this task, current upsampling methods used in these approaches only utilize the local information of each pixel in the low-resolution multispectral (LRMS) image while neglecting to exploit its global information as well as the cross-modal information of the guiding panchromatic (PAN) image, which limits their performance improvement. To address this issue, this paper develops a novel probability-based global cross-modal upsampling (PGCU) method for pan-sharpening. Precisely, we first formulate the PGCU method from a probabilistic perspective and then design an efficient network module to implement it by fully utilizing the information mentioned above while simultaneously considering the channel specificity. The PGCU module consists of three blocks, i.e., information extraction (IE), distribution and expectation estimation (DEE), and fine adjustment (FA). Extensive experiments verify the superiority of the PGCU method compared with other popular upsampling methods. Additionally, experiments also show that the PGCU module can help improve the performance of existing SOTA deep learning pansharpening methods. The codes are available at https://github.com/Zeyu-Zhu/PGCU.Comment: 10 pages, 5 figure

Joint relay selection and resource allocation for energy-efficient D2D cooperative communications using matching theory

Device-to-device (D2D) cooperative relay can improve network coverage and throughput by assisting users with inferior channel conditions to implement multi-hop transmissions. Due to the limited battery capacity of handheld equipment, energy efficiency is an important issue to be optimized. Considering the two-hop D2D relay communication scenario, this paper focuses on how to maximize the energy efficiency while guaranteeing the quality of service (QoS) requirements of both cellular and D2D links by jointly optimizing relay selection, spectrum allocation and power control. Since the four-dimensional matching involved in the joint optimization problem is NP-hard, a pricing-based two-stage matching algorithm is proposed to reduce dimensionality and provide a tractable solution. In the first stage, the spectrum resources reused by relay-to-receiver links are determined by a two-dimensional matching. Then, a three-dimensional matching is conducted to match users, relays and the spectrum resources reused by transmitter-to-relay links. In the process of preference establishment of the second stage, the optimal transmit power is solved to guarantee that the D2D link has the maximized energy efficiency. Simulation results show that the proposed algorithm not only has a good performance on energy efficiency, but also enhances the average number of served users compared to the case without any relay

Refractive Index-Matched PIV Experiments and CFD Simulations of Mixing in a Complex Dynamic Geometry

Acknowledgment The authors appreciatively acknowledge the financial support from the National Key Research and Development Program of China (No.2016YFB0302801), National Natural Science Foundation of China (No.21676007), the Fundamental Research Funds for the Central Universities (XK1802-1) and the China Scholarship Council.Peer reviewedPostprin

Structural Investigation of a Self-Cross-Linked Chitosan/Alginate Dialdehyde Multilayered Film with in Situ QCM-D and Spectroscopic Ellipsometry

A chitosan/alginate dialdehyde multilayered film was fabricated using the layer-by-layer assembly method. Besides electrostatic interaction that promotes alternate adsorption of the oppositely charged polyelectrolytes, the Schiff base reaction between the amine groups on chitosan and the aldehyde groups on alginate dialdehyde provides a covalently cross-linked film, which after reduction by sodium cyanoborohydride is stable under both acidic and alkaline conditions. Moreover, the cross-linked film is responsive to changes in pH and addition of multivalent salts. The structural properties of the multilayered film such as thickness, refractive index, and water content were examined using simultaneous quartz crystal microbalance with dissipation monitoring and spectroscopic ellipsometry