Search

This paper proposes an analytical method for effectively evaluating the performances of zero-bias diode-based RF power harvesters. The method allows the accurate calculation of both the diode power conversion efficiency (PCE) and matching efficiency, while showing the wide adaptability to frequency and input power. To calculate the diode PCE accurately, the junction voltage is built based on modeling the diode junction capacitance and turn-on voltage. Using the accurate diode PCE, the equivalent nonlinear resistance of the diode is calculated, and thus the diode impedance is obtained. This helps to design a matching network with required bandwidths and evaluate the corresponding matching efficiency. The total PCE of the RF power harvester is finally obtained by multiplying the diode PCE and matching efficiency. For verification, dual-band RF power harvesters based on diodes of SMS7630 and HSMS-2850 are developed to cover the two 5G frequency bands for three telecom operators in China (2.515-2.675, 3.4-3.5 & 3.5-3.6 GHz). They are designed to operate in the low power range of −25-−5 dBm for low power harvesting scenarios. Compared with the simulated results, the calculation discrepancy of less than 3.12% can be achieved in evaluating the total PCEs of the RF power harvesters. Prototypes of the designed RF power harvesters were fabricated and measured for validation. It shows that the proposed analytical method can provide design guidelines for developing a multi-band RF power harvester. [ABSTRACT FROM AUTHOR]

Venture capital market is one of the most important financial markets, which plays an important role in promoting industrial innovation and economic development. In this study, the complete data set of all venture capital events occurred in China from 2009 to 2020 was used to construct two kinds of complex networks, whose topological property and dynamic evolution trend of the network are studied. Specifically, we construct the co-investment network among investor, as well as the binary complex network of investor-entrepreneur, and propose the evaluation method of the importance and performance of venture capital institutions. Based on the proposed method, we identify some leading venture capital institutions with high performance and importance. Furthermore, this paper enlightens venture capital practitioners by discovering the investment behavior and preference of these leading institutions. [ABSTRACT FROM AUTHOR]

In the 13th century, the Chinese emperor Kublai Khan embarked on a bold experiment. China at the time was divided into different regions, many of which issued their own coins, discouraging trade within the empire. So Kublai Khan decreed that henceforth money would take the form of paper. [ABSTRACT FROM PUBLISHER]

This article provides information on the economic and social conditions in China. China's population density is 4.5 times that of the U.S., though the two are almost identical in size. The European Union, while much smaller geographically, is almost as densely populated as China. Chengdu, the birthplace of paper currency, is a one-time capital of China that is also one of its oldest cities. In part because of the country's enormous population, China's gross domestic product has become second in the world to that of the U.S. And the region's arable land is only 15 percent of its total land area.

The country's first manned science sub goes for global bragging rights – When a team of Chinese engineers set out to build the deepest-diving submersible in the world, they had never laid eyes on a manned deepsea vehicle. "We had only read some reference papers that had pictures; there was no chance for us to see a real manned submersible," says Cui Weicheng, deputy director of the China Ship Scientific Research Center and project manager for the new sub. "We were starting from the very beginning." [ABSTRACT FROM PUBLISHER]