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Undesirable vibration in pipeline structures due to internal gas/liquid coupling, mechanical vibration, and water hammer action may cause machine shutdown, leakage, fatigue failure, and sometimes catastrophic explosion. It is necessary to design a device to mitigate pipeline vibration. This paper proposes a new type of particle damper, the multi-cavity particle damper (MPD). A mechanical MPD model is first proposed. Second, the analytical solutions of the MPD are given for the case of two symmetric impacts per cycle. A corresponding method for numerically simulating more general cases is also proposed, and the optimal movement distance is established using the analytical solution. Third, shaking table tests are carried out on pipeline structures controlled by an MPD subjected to harmonic excitation, and the control effects are verified. Finally, a parametric study is conducted, and the MPD design is discussed. The MPD is found to have a significant damping effect that can reduce the response by 98% in resonant cases. Shaking table tests verify the analytical solution, numerical simulation, and optimization method. [ABSTRACT FROM AUTHOR]

In response to the current demand for intelligent detection in rail transit, we need to strengthen the support role of technological innovation in rail transit, and apply new technologies to the field of subway construction and operation in a forward-looking manner to improve operation and maintenance capabilities. In view of the limited methods of current section condition monitoring and the low efficiency and poor accuracy of traditional manual measurement methods, this paper elaborates in detail on the use of different intelligent detection methods to solve the following problems: the hidden defects of ring network cables are difficult to detect; the field strength of the wireless communication system in subway tunnels cannot be continuously measured; the impact of foreign object intrusion in subway tunnels is significant. This study can improve measurement accuracy and efficiency, detect and solve abnormal problems in advance, and improve the safety of section equipment. [ABSTRACT FROM AUTHOR]

Centralized fiscal transfers to the provinces are the principal means of reducing income inequalities in China. The coastal provinces are the main transfer donors to the poorer provinces. We evaluate if the equity objective sacrifices aggregate growth using four panel vector auto-regressions (PVARs) for four geographical regions of Chinese provinces. The PVARs are estimated for centralized transfers, government spending, taxes and output from 1994 to 2018, whether or not transfers sacrifice growth depends on geography. Transfers reduce inequality and generate growth in the middle provinces; reduce inequality but sacrifice growth in the western provinces; and worsen inequality and sacrifice growth in the northeast provinces. [ABSTRACT FROM AUTHOR]

Dual-band electrochromic (EC) smart windows are a promising energy-saving technology because they can control indoor temperature by modulating the transmitted light in visible and near-infrared (NIR) regions. The key to smart windows is the preparation of well-performed dual-band EC materials (ECMs). Prussian blue (PB) is a typical anodic ECM with multiple colors, high capacity, and excellent electrochemical activity. However, due to the lattice expansion and low electron density of PB, the poor cycling stability and tedious modulation in the NIR region severely limit its wide application. Herein, we proposed a stabilization strategy to construct a one-dimensional WO3 array-modified PB with porous core–shell structures (named PB@WO3). Because of the porous structure and the heterostructure between WO3 and PB, the PB@WO3 showed excellent stability (the current density did not exhibit obvious changes after 1000 cycles) and high coloring efficiency (62.3 cm2/C). Besides, the modification of WO3 also provided PB@WO3 with a dual-band modulation ability under low voltages (35.14% at 633 nm, 60.55% at 1200 nm, and 67.18% at 1800 nm). Simultaneously, the combination of WO3 and PB rendered PB@WO3 with three colors, i.e., white, blue, and green. Furthermore, the one-dimensional array structure and the interaction between WO3 and PB imparted PB@WO3 with fast switching speed (0.5 and 0.5 s per each coloration and bleaching cycle, respectively). [ABSTRACT FROM AUTHOR]

Wearable strain sensors are expected to meet the requirements of high sensitivity, facile fabrication, and high aesthetics to realize practical applications. However, reported sensitive strain sensors fail to exhibit multicolor due to high light absorption. Herein, a flexible strain sensor with high sensitivity and color‐exhibition ability is fabricated by half‐embedding silver nanowires (AgNWs) into dyeable thermoplastic polyurethane (TPU) films through thermal annealing. A sheet resistance of 11.5 Ω sq−1 and a transmittance above 79.9% at 550 nm is obtained for intact AgNWs/TPU films. A gauge factor of 34 797 is achieved at a tensile strain of 9%, indicating the high sensitivity for monitoring tiny movement changes. Besides, the high transparency allows color exhibition after dying. The multicolor AgNWs/TPU films are further rolled into rod‐shaped yarns and weaved with commercial yarns to form wearable colorful electronics. [ABSTRACT FROM AUTHOR]

Ultralong carbon nanotubes (CNTs) are believed to be ideal candidates for various high‐end applications because of their macroscale lengths, perfect structures, and excellent mechanical and electrical properties. The key to the wide application of ultralong CNTs is their controlled synthesis and mass production. Ultralong CNTs usually follow a flying kite‐like growth mechanism, during which process there exists a thermal buoyancy that keeps ultralong CNTs floating in the gas flow. However, it remains vague for a long time about the origin of this thermal buoyancy. Herein, a simple and quantitative heat balance model is proposed to describe the inherent thermal effect of substrates, which explains the origin of the temperature difference between the substrate and the gas flow. The inherent thermal effect is found to be positively correlated with the emissivity of the substrates. Then, the local temperature gradient induced by the inherent thermal effect is found to result in both natural convection and thermophoresis. Thermophoretic force is proven to be the dominant driving force for lifting the ultralong CNTs up from the substrates. By utilizing the inherent thermal effect and designing the local temperature distribution, the areal density and orientation of ultralong CNT arrays are modulated. [ABSTRACT FROM AUTHOR]