Human health risks caused by PM
raise awareness to the role of trees as bio-filters of urban air pollution, but not all species are equally capable of filtering the air. The objectives of this ...current study were: (1) to determine the foliar traits for effective PM
-capture and (2) explore species-to-species differences in foliar PM
-recapture capacity following a rain event. The study concluded that overall, the acicular needle shape made conifers more efficient with PM
accumulation and post-rainfall recapture than broadleaved species. The foliar shape and venation of broadleaved species did not appear to influence the PM
accumulation. However, the number of the grooves and trichomes of broadleaved species were positively related to foliar PM
accumulation, suggesting that they could be used as indicators for the effectiveness of tree PM
capture. Furthermore, the amount of PM
removal by rainfall was determined by the total foliar PM
. Not all PM
remained on the foliage. In some species, PM
was resuspended during the growing season, and thus reduced the net particular accumulation for that species. These findings contribute to a better understanding of tree species potential for reducing PM
in urban environments.
UWB technology is a wireless carrier communication technology that uses frequency bandwidth above 1GHz. This essay mainly focuses on the theory of UWB and one of its most important applications, ...which is indoor positioning. It will explore some possibilities of UWB in the field of precise positioning. Based on the literature, the theory of UWB and the algorithm of positioning will be shown in a relatively simple way. The result shows that Ultra Wide Band (UWB) technology has the advantages of low system complexity, low power spectral density of transmitted signal, and insensitivity to channel fading. The positioning system based on UWB can be used for the real-time location management of personnel, equipment, and vehicles, as well as to view the real-time location and distribution area of the target., such as nursing home elderly positioning monitoring, to prevent the elderly from getting lost, location management of chemical plant operators, security of dangerous areas, location management of vehicles and equipment, etc.
We report a KOH self-templating synthesis of three-dimensional hierarchical porous carbon using resol as the precursor and KOH as both the template and activating agent. The resulting resol-derived ...porous carbon (RPC) exhibits a high surface area (up to 2700 m super(2) g super(-1)) and well-interconnected macropores with micropores and mesopores decorated on the carbon walls. Consequently, the RPC shows low internal resistance, high specific capacitance, good rate capability and excellent cycling stability in 6 M KOH as a supercapacitor electrode. Because of its easy fabrication and low cost, it offers a good alternative method for synthesis of carbon electrodes for energy-storage devices such as Li-ion batteries, fuel cells and supercapacitors.
Recently, with the rapid development of mobile sensing technology, capturing scene information by mobile sensing devices in the form of images or videos has become a prevalent recording method. ...However, the moiré pattern phenomenon may occur when the scene contains digital screens or regular strips, which greatly degrade the visual performance and image quality. In this paper, considering the complexity and diversity of moiré patterns, we propose a novel end-to-end image demoiré method, which can learn moiré pattern elimination in both the frequency and spatial domains. To be specific, in the frequency domain, considering the signal energy of moiré pattern is widely distributed in the frequency, we introduce a wavelet transform to decompose the multi-scale image features, which can help the model identify the moiré features more precisely to suppress them effectively. On the other hand, we also design a spatial domain demoiré block (SDDB). The SDDB module can extract moiré features from the mixed features, then subtract them to obtain clean image features. The combination of the frequency domain and the spatial domain enhances the model’s ability in terms of moiré feature recognition and elimination. Finally, extensive experiments demonstrate the superior performance of our proposed method to other state-of-the-art methods. The Grad-CAM results in our ablation study fully indicate the effectiveness of the two proposed blocks in our method.
Renewable energy resources (RES), e.g., solar photovoltaic (PV), wind energy, and electric vehicles (EVs) are extensively integrated into modern power electronics-based power systems due to their ...sustainable and environmentally friendly features. This has gradually reshaped the frequency regulation structure of power systems. Specifically, the duty of frequency regulation, previously supported by synchronous generators, will be taken over by grid-tied power converters (such as EV chargers), which can be controlled as virtual synchronous machines (VSMs) to mimic the inertial response of synchronous generators. However, being different from synchronous generators, VSMs enable fast frequency regulation. As a consequence, it is identified in this paper that the elimination of frequency oscillations is possible. Therefore, instead of simply increasing inertia for oscillations suppression, the desirable inertia coefficient can be different for various cases. In order to illustrate this point, relationships between several important performance indices, such as the rate-of-change-of-frequency, frequency nadir, overshoot, settling time, and inertia coefficient, are analyzed in detail. Furthermore, a straightforward method for designing the optimal inertia coefficient for VSMs is put forward. Finally, experiment results obtained from a 1-kW three-phase VSM prototype are demonstrated to validate the effectiveness of the theoretical analysis and proposed design method.
Objective
To compare the efficacy of laparoscopic pancreaticoduodenectomy (LPD) and open pancreaticoduodenectomy (OPD) in a medium-volume medical center.
Methods
Data for patients who underwent OPD ...or LPD for carcinoma of the ampulla of Vater (VPC) between January 2017 and June 2022 were acquired retrospectively. Propensity score-matching (PSM) analysis was performed to balance the baseline characteristics between the groups. The primary outcome was disease-free survival (DFS). Cox regression analysis was used to explore the independent risk factors for DFS.
Results
A total of 124 patients with pathologically diagnosed VPC were included. After 1:1 matching, there were 23 cases each in the OPD and LPD groups. Kaplan–Meier survival analyses showed that the median DFS in the OPD and LPD groups was identical (16.0 months vs 16.0 months, respectively). Multivariate Cox regression analysis showed that low levels of alkaline phosphatase and γ-glutamyl transpeptidase, positive surgical margin, and lymph node enlargement were independent risk factors for DFS.
Conclusion
LPD in medium-volume centers with acceptable technical conditions may approach or even achieve the efficacy of LPD in large-volume centers.
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