The traction blockade in depots of multiple electric multiple units (EMUs) is generally considered to be caused by the voltage low frequency oscillation (LFO) of the high-speed railway traction ...network. As a possible solution, a strategy using single-phase EMUs rectifiers with passivity-based control (PBC) is proposed in this paper. First, the mathematical model of the four-quadrant pulse width modulation rectifier is constructed based on the port controlled Hamiltonian with dissipation. Next, with the insertion of damping, the new energy function can be minimized at the equilibrium point of the system, which enables the derivation of the rectifier control law based on the interconnection and damping assignments PBC. Comparison of simulation results with those of the traditional proportional integral (PI) scheme, autodisturbance rejection control and multivariable control verifies that the proposed PBC controller has better dynamic and static performance. Among all strategies considered, the resulting line current has the least total harmonic distortion, and the dc-link voltage of single-phase EMUs rectifier has the least oscillation and the shortest adjustment time, when using the PBC. Meanwhile, the simulations of multi-EMUs accessed a traction network show that the proposed method significantly suppresses the voltage LFO of the traction network. Finally, the LFO signal modal analysis is performed using the fast Fourier transform and the estimating signal parameters via the rotational invariance techniques. It indicates that PBC can suppress the symmetrical frequency components and effectively reduce the third, fifth, and other harmonic components compared with the PI control in EMUs.
A kind of new fused‐ring electron acceptor, IDT‐OB, bearing asymmetric side chains, is synthesized for high‐efficiency thick‐film organic solar cells. The introduction of asymmetric side chains can ...increase the solubility of acceptor molecules, enable the acceptor molecules to pack closely in a dislocated way, and form favorable phase separation when blended with PBDB‐T. As expected, PBDB‐T:IDT‐OB‐based devices exhibit high and balanced hole and electron mobility and give a high power conversion efficiency (PCE) of 10.12%. More importantly, the IDT‐OB‐based devices are not very sensitive to the film thickness, a PCE of 9.17% can still be obtained even the thickness of active layer is up to 210 nm.
A new fused‐ring electron acceptor (IDT‐OB), bearing asymmetric side chains, is facilely synthesized for high‐efficiency thick‐film organic solar cells. The asymmetric structure makes it easier to form ideal phase separation when blended with a polymer donor. Power conversion efficiencies of 10.12% and 8.57% are obtained with active‐layer thicknesses of 130 and 320 nm, respectively.
Perfluoroalkyl acids (PFAAs) are a group of emerging persistent organic pollutants (POPs), which have been ubiquitously detected in the environmental media. However, national scale investigations on ...their occurrence and distribution in drinking water are still insufficient. In this study, we detected the 17 priority PFAAs in drinking water from 79 cities of 31 provincial-level administrative regions throughout China, and investigated their occurrence and distribution. Additionally, we also analyzed the influencing factors on their profiles, such as the existence of industrial sources, socioeconomic factors (population density and GDP), and assessed levels of risk associated with contaminated drinking water. On the national scale, the sum concentrations of the 17 PFAAs (∑17PFAAs) in drinking water was in a range of 4.49–174.93 ng/L with a mean value of 35.13 ng/L. Among the 17 individual PFAAs, perfluorobutanoic acids (PFBA) was the most abundant individual PFAAs with the median concentration of 17.87 ng/L, followed by perfluorooctanoic acid (PFOA, 0.74 ng/L), perfluorononanoic acid (PFNA, 0.40 ng/L) and perfluorooctane sulfonic acid (PFOS, 0.25 ng/L). The geographic distribution characteristic of ∑17PFAAs in drinking water was in a descending order of Southwestern China (57.67 ng/L) > Eastern coastal China (32.85 ng/L) > Middle China (29.89 ng/L) > Northwestern China (28.49 ng/L) > Northeastern China (22.03 ng/L), and in general, the existence of the industrial sources could positively affect the contamination levels of PFAAs in drinking water. The pollution level of PFAAs in drinking water also varied among the three different city levels (medium-sized city > big city > town). In towns, the positive correlations were observed between the population density and the ∑17PFAAs (R2 = 0.45, p < 0.01), and the individual concentration of PFHxA, PFBS, and PFOA (p < 0.01). Moreover, besides PFAAs in Yunnan, Jiangsu, and Jiangxi, concentrations of related PFAAs in drinking water from 28 provinces were less than the suggested drinking water advisories. The relatively higher concentrations of PFAAs in Yunnan, Jiangsu, and Jiangxi suggest that further studies focusing on their sources and potential health risk to humans are needed.
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•The nationwide occurrence of PFAAs in drinking water of China was investigated.•PFBA, PFOA, and PFHxS were dominated components in drinking water.•PFAAs concentration in drinking water varied among different regions and city levels of China.•PFAAs in drinking water might not pose a serious risk in most sample sites.
Promoting efficiency, deformability, and life expectancy of stretchable organic solar cells (OSCs) have always been key concerns that researchers are committed to solving. However, how to improve ...them simultaneously remains challenging, as morphology parameters, such as ordered molecular arrangement, beneficial for highly efficient devices actually limits mechanical stability and deformability. In this study, the unfavorable trade‐off among these properties has been reconciled in an all‐polymer model system utilizing a mechanically deformable guest component. The success of this strategy stems from introducing a highly ductile component without compromising the pristine optimized morphology. Preferable interaction between two donors can maintain the fiber‐like structure while enhancing the photocurrent to improve efficiency. Morphology evolution detected via grazing incidence X‐ray scattering and in situ UV–vis absorption spectra during stretching have verified the critical role of strengthened interaction on stabilizing morphology against external forces. The strengthened interaction also benefits thermal stability, enabling the ternary films with small efficiency degradation after heating 1500 h under 80 °C. This work highlights the effect of morphology evolution on mechanical stability and provides new insights from the view of intermolecular interaction to fabricate highly efficient, stable, and stretchable/wearable OSCs.
The intermolecular interaction in an all‐polymer system is well modulated through incorporating a third component, resulting simultaneous enhancement of efficiency, deformability, and mechanical stability. Better mechanical stability against multiple forces in optimized ternary system is achieved through strengthening intermolecular interaction between two donors to inhibit the morphology evolution under strain.
While the concept of intercellular mechanical communication has been revealed, the mechanistic insights have been poorly evidenced in the context ofmyofibroblast–fibroblast interaction during ...fibrosis expansion. Here we report and systematically investigate the mechanical force-mediated myofibroblast–fibroblast cross talk via the fibrous matrix, which we termed paratensile signaling. Paratensile signaling enables instantaneous and long-range mechanotransduction via collagen fibers (less than 1 s over 70 μm) to activate a single fibroblast, which is intracellularly mediated by DDR2 and integrin signaling pathways in a calcium-dependent manner through the mechanosensitive Piezo1 ion channel. By correlating in vitro fibroblast foci growth models with mathematical modeling, we demonstrate that the single-cell-level spatiotemporal feature of paratensile signaling can be applied to elucidate the tissue-level fibrosis expansion and that blocking paratensile signaling can effectively attenuate the fibroblast to myofibroblast transition at the border of fibrotic and normal tissue. Our comprehensive investigation of paratensile signaling in fibrosis expansion broadens the understanding of cellular dynamics during fibrogenesis and inspires antifibrotic intervention strategies targeting paratensile signaling.
•A novel coupling scheme of GEHP and condensing gas boiler is proposed.•The flue gas heat exchanger adopts cast silicon aluminum heat exchanger.•The GEHP &CB system energy efficiency can reach ...110%.•The payback period of the increased initial investment is 1.4 heating seasons.
How to improve the utilization efficiency of natural gas and achieve the goal of carbon reduction has gradually become the focus of people’s attention. The exhaust temperature of the condensing gas boiler is between 50℃ and 80℃, which still contains some heat that is not used, so it is necessary to recover this part of the heat. This paper mainly studies the total heat recovery and utilization of waste heat from low-temperature flue gas of condensing gas boiler. In the research field of gas boiler flue gas waste heat recovery, the use of gas compression heat pump to recover gas boiler flue gas waste heat is still very few. Based on the principle of reducing the cold source temperature, a low-temperature flue gas recovery scheme of a gas engine-driven compression heat pump coupled condensing gas boiler is proposed. The low-temperature chilled water produced by gas engine-driven compression heat pump is used to recover flue gas waste heat from condensing gas boiler and gas engine, which can improve the utilization efficiency of natural gas and eliminate the “white smoke phenomenon” simultaneously. In addition, the waste heat of flue gas is used as the low-temperature heat source of gas engine-driven compression heat pump to ensure the stable operation of the heat pump in the low-temperature environment. The flue gas waste heat recovery technology has been improved compared with other flue gas waste heat recovery technologies in terms of primary energy utilization efficiency, system stability, corrosion resistance of flue gas heat exchangers, and investment recovery cycle. The experimental results show that when the water inlet temperature of the flue gas heat exchanger is 15℃, the overall power of the unit can reach 645 kW, and the final exhaust temperature is below 25℃. The overall primary energy utilization rate of the GEHP&CB can reach 110 %, which is 10 %∼20 % higher than that of the condensing gas boiler. The payback period of the increased initial investment is 1.4 heating seasons. Due to the improvement of natural gas utilization efficiency significantly reduces natural gas consumption and pollutant discharge.
Plasmonic nanolaser holds great potential in breaking down the diffraction limit of conventional optics to the deep sub‐wavelength regime and in ultrafast lasing dynamics. However, plasmonic laser ...devices are constrained in practical applications due to their high cost and high thresholds. All‐inorganic cesium lead halide perovskites are promising solutions for their excellent optical gain properties and high emission efficiency. In this work, high‐quality single‐crystalline CsPbBr3 perovskite nanowires (NWs) are synthesized by chemical vapor deposition method. The plasmonic lasing is achieved from the CsPbBr3 nanowire based plasmonic devices with lasing threshold down to ≈6.5 µJ cm−2 at room temperature. The highly polarized emission parallel to nanowire axis and polarization‐sensitive pump response confirm the plasmonic characteristic in these devices. Furthermore, time‐resolved photoluminescence study suggests that the radiative recombination lifetime of CsPbBr3 NW is shortened by a factor of ≈6.14 due to Purcell effect. The lasing threshold of plasmonic device increases along with the nanowire length, indicating greater potential in small size and integration in plasmonic device than its photonic counterparts. The results not only provide a solution to fabricate low‐cost nanowire based plasmonic lasers, but also advocate the prospect of all‐inorganic perovskite nanowires as promising candidates in plasmonic‐based devices.
Plasmonic nanolaser holds great potential in breaking down the diffraction limit of conventional optics to deep sub‐wavelength regime. Herein, all‐inorganic CsPbBr3 nanowire based plasmonic lasers are demonstrated at room tempearutre with threshold ≈6.5 µJ cm−2. The lasing threshold of plasmonic device increases along with the nanowire length, indicating greater potential in plasmonic integration device than its photonic couterparts.
Electrothermal characteristics play a crucial role in ladle furnaces that utilize electric energy for heating purposes. In this paper, a three-dimensional electrothermal power calculation model of ...ladle furnace is established based on electromagnetism, the influence of thickness and relative foaming height of refining slag on electrothermal characteristics was studied, and the electrical conductivity of refining slag was measured using AC impedance method. The study revealed that the electrical conductivity of the primary slag and final slag is 101 S/m and 92 S/m respectively at 1575 °C. During energization and heating, the current is mainly conducted through electrodes, arcs, and molten steel, the three-phase current is finally connected in the molten steel near the interface between slag and molten steel, and a small amount of current is connected through refining slag. The electrothermal power of the arc accounts for the largest proportion of the total electrothermal power, reaching 96.8%, while the electrothermal power of the molten steel is the smallest. When the thickness of the refining slag increases from 0 mm to 150 mm, the electrothermal power of the refining slag increases from 0 kW to 759.7 kW, while the electrothermal power of the molten steel and arc decrease from 60.9 kW, 18783.5 kW to 44.3 kW and 17440.2 kW, respectively. When the relative foaming height increases from 0 to 150%, the electrothermal power of refining slag increases from 412.4 kW to 449.6 kW, and the electrothermal power of molten steel and arc decreases from 54.1 kW, 18172.1 kW to 51.1 kW and 17194.3 kW, respectively.
Microplastics (MPs) in sediment environments have been widely reported. As the number of samples increases, establishing a reliable and effective method becomes increasingly urgent for the rapid ...extraction and identification of MPs in sediments. Herein, we proposed a system with continuous density flotation of NaBr-ZnCl2 (mixture of NaBr and ZnCl2) solution for extracting MPs in a sediment sample, combined with micro-Fourier transform infrared (μ-FT-IR) imaging scanning for identification of MPs. The recoveries of MPs were estimated for four different sizes, shapes, and ten different types of polymers. The results indicated NaBr-ZnCl2 solution showed a high recovery rate from 88.33% to 100.00% for extracting these different MPs. The μ-FT-IR imaging scanning allows for the detection of plastic down to the size of 6.25 μm in filed samples, and merely takes about 3 min, which was validated by testing of sediments from Jiaozhou Bay, China and its adjacent estuaries.
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•An optimized procedure for MPs extraction from sediment was proposed.•NaBr-ZnCl2 was the best among the 4 solutions for density flotation extraction of MPs from sediment.•The proposed method was validated by testing with field sediment samples.
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