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141.
对反射声波的复杂操控是声学研究的基础问题之一,并广泛应用于房间声学设计及噪声能量消除等重要场合。近年来出现的声学超表面为声学功能器件的小型化提供了新的启示,因此如何进一步缩减其尺寸和重量具有重要的物理意义与应用价值。展示了一种轻薄超表面结构对低频空气声波所产生反射声场的高效、精准操控。通过理论计算证明了利用简单的扁平中空结构,可在不显著牺牲能量反射率及结构强度的前提下,通过调控单个结构参数产生0~2π范围内的反射相位,同时避免了制备难度高和增加器件重量的复杂内部结构,因此具有尺寸超薄(λ0/20)、重量轻盈、反射率高及制备简单等优势。通过实现任意角度的异常反射、基于超薄平面透镜的可调声聚焦、构建平面棱锥镜产生类贝塞尔声束3个典型例子展示了该器件对反射声波的丰富操控性能。实现基于轻薄超表面对反射声场的操控,有助于新型平面声学器件的研究与应用,并有望在建筑声学、噪声控制、扬声器设计等领域中产生重要价值。 相似文献
142.
Yu Liu Qi Wan Juan Gong Zhiwei Liu Gang Tao Jie Zhao Le Chen Wenshu Li Xijun Wei Ling Ni Yingze Song 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(8):2206400
The fast electrochemical kinetics behavior and long cycling life have been the goals in developing anode materials for potassium ion batteries (PIBs). On account of high electron conductivity and theoretical capacity, transition metal selenides have been deemed as one of the promising anode materials for PIBs. Herein, a systematic structural manipulation strategy, pertaining to the confine of Fe3Se4 particles by 3D graphene and the dual phosphorus (P) doping to the Fe3Se4/3DG (DP-Fe3Se4/3DG), has been proposed to fulfill the efficient potassium-ion (K-ion) evolution kinetics and thus boost the K-ion storage performance. The theoretical calculation results demonstrate that the well-designed dual P doping interface can effectively promote K-ion adsorption behavior and provide a low energy barrier for K-ion diffusion. The insertion-conversion and adsorption mechanism for multi potassium storage behavior in DP-Fe3Se4/3DG composite has been also deciphered by combining the in situ/ex situ X-ray diffraction and operando Raman spectra evidences. As expected, the DP-Fe3Se4/3DG anode exhibits superior rate capability (120.2 mA h g−1 at 10 A g−1) and outstanding cycling performance (157.9 mA h g−1 after 1000 cycles at 5 A g−1). 相似文献
143.
Yanhong Ma Wenyu Jiang Yuanqing Xu Yong Zhang 《Advanced materials (Deerfield Beach, Fla.)》2019,31(45)
Multisegmented metallic nanorods (MS‐M‐NRs) have attracted increasing attention thanks to their integrated structures and complex functions. The integration of nanoscale segments in 1D enables maximum exposure of each segment and enhanced interaction between adjacent segments. Such structural integration will induce functional complexity in the nanorods, leading to superior properties for the individual components. Herein, recent progress on the development of MS‐M‐NRs is reviewed. Their precise fabrication, nanoscale manipulation, and subwavelength imaging, as well as simultaneous manipulation and imaging are discussed, respectively. Specifically, precise fabrication of MS‐M‐NRs focuses on porous anodic alumina (PAA) templated electrodeposition, which enables sub‐10 nm growth of the segments and their interfaces/fronts. Nanoscale manipulation of MS‐M‐NRs introduces the fundamental methods that are employed for delicate movement control on the nanorods through internal or external stimulations. Subwavelength imaging of MS‐M‐NRs highlights the achievements on identification and location of constituent nanoscale segments/gaps based on their differences and interactions. Simultaneous manipulation and imaging of MS‐M‐NRs addresses the significance and potential applications of the nanorods with magnetic–plasmonic dual modulation. The development of MS‐M‐NRs will greatly contribute to materials science and nanoscience/nanotechnology. 相似文献
144.
In this paper, we propose an algorithm for fully automatic neural face swapping in images and videos. To the best of our knowledge, this is the first method capable of rendering photo-realistic and temporally coherent results at megapixel resolution. To this end, we introduce a progressively trained multi-way comb network and a light- and contrast-preserving blending method. We also show that while progressive training enables generation of high-resolution images, extending the architecture and training data beyond two people allows us to achieve higher fidelity in generated expressions. When compositing the generated expression onto the target face, we show how to adapt the blending strategy to preserve contrast and low-frequency lighting. Finally, we incorporate a refinement strategy into the face landmark stabilization algorithm to achieve temporal stability, which is crucial for working with high-resolution videos. We conduct an extensive ablation study to show the influence of our design choices on the quality of the swap and compare our work with popular state-of-the-art methods. 相似文献
145.
《Information & Management》2020,57(6):103244
Online reviews have a significant influence on consumers, and consequently firms are motivated to manipulate online reviews to promote their own products. This paper develops an analytical model to systematically explore the impact of online review manipulation on asymmetrical firms who sell substitutable search products in a competing market. Results show that a firm’s manipulation of online reviews is not necessary to hurt its competitor’s profit. In addition, if firms are free to choose whether to manipulate online reviews, both firms will always choose to manipulate online reviews. Moreover, there exists a prisoner’s dilemma in which online reviews are overmanipulated. 相似文献
146.
147.
Byungsoo Kim Oliver Wang A. Cengiz Öztireli Markus Gross 《Computer Graphics Forum》2018,37(2):329-338
In this work, we present a method to vectorize raster images of line art. Inverting the rasterization procedure is inherently ill‐conditioned, as there exist many possible vector images that could yield the same raster image. However, not all of these vector images are equally useful to the user, especially if performing further edits is desired. We therefore define the problem of computing an instance segmentation of the most likely set of paths that could have created the raster image. Once the segmentation is computed, we use existing vectorization approaches to vectorize each path, and then combine all paths into the final output vector image. To determine which set of paths is most likely, we train a pair of neural networks to provide semantic clues that help resolve ambiguities at intersection and overlap regions. These predictions are made considering the full context of the image, and are then globally combined by solving a Markov Random Field (MRF). We demonstrate the flexibility of our method by generating results on character datasets, a synthetic random line dataset, and a dataset composed of human drawn sketches. For all cases, our system accurately recovers paths that adhere to the semantics of the drawings. 相似文献
148.
Gunhyu Bae Yoo Sang Jeon Min Jun Ko Yuri Kim Seong-Beom Han Ramar Thangam Wonsik Kim Hee Joon Jung Sungkyu Lee Hyojun Choi Sunhong Min Hyunsik Hong Sangwoo Park Seong Yeol Kim Kapil D. Patel Na Li Jeong Eun Shin Bum Chul Park Hyeon Su Park Jun Hwan Moon Yu Jin Kim Uday Kumar Sukumar Jae-Jun Song Soo Young Kim Seung-Ho Yu Yun Chan Kang Steve Park Seung Min Han Dong-Hwee Kim Ki-Bum Lee Qiang Wei Liming Bian Ramasamy Paulmurugan Young Keun Kim Heemin Kang 《Advanced functional materials》2021,31(37):2103409
Developing materials with the capability of changing their innate features can help to unravel direct interactions between cells and ligand-displaying features. This study demonstrates the grafting of magnetic nanohelices displaying cell-adhesive Arg-Gly-Asp (RGD) ligand partly to a material surface. These enable nanoscale control of rapid winding (“W”) and unwinding (“UW”) of their nongrafted portion, such as directional changes in nanohelix unwinding (lower, middle, and upper directions) by changing the position of a permanent magnet while keeping the ligand-conjugated nanohelix surface area constant. The unwinding (“UW”) setting cytocompatibility facilitates direct integrin recruitment onto the ligand-conjugated nanohelix to mediate the development of paxillin adhesion assemblies of macrophages that stimulate M2 polarization using glass and silicon substrates for in vitro and in vivo settings, respectively, at a single cell level. Real time and in vivo imaging are demonstrated that nanohelices exhibit reversible unwinding, winding, and unwinding settings, which modulate time-resolved adhesion and polarization of macrophages. It is envisaged that this remote, reversible, and cytocompatible control can help to elucidate molecular-level cell–material interactions that modulate regenerative/anti-inflammatory immune responses to implants. 相似文献
149.
Due to the limited carrier concentration, 2D transition metal dichalcogenides have lower intrinsic dark current, and thus, are widely studied for high performance room photodetection. However, the light-matter interaction is still unclear, thus tuning the photoexcitation and further manipulating the photodetection is a challenge. Herein, large-area PtS films are synthesized, and the growth mechanism is investigated. It is demonstrated that PtS has an orthorhombic structure and exhibits the p-type semiconducting behavior. Then, MoS2/PtS p–n heterojunction is fabricated, and its energy diagram is discussed based on the Kelvin probe force microscopy. The contact potential difference is about 160 mV, which is much larger than previous 2D junctions facilitating the charge separation. Furthermore, the phototransistor based on MoS2/PtS p–n heterojunction is prepared, showing broadband photoresponse from visible to near-infrared. The manipulation of an external field on photoresponse, detectivity, and rise/fall time are explored and discussed. The responsivity can reach up to 25.43 A W−1, and the detectivity is 8.54 × 1012 Jones. These results indicate that PtS film is a prospective candidate for high-performance optoelectronic devices and broaden the scope of infrared detection materials. 相似文献
150.
Xiaonan Zhao Yanan Dong Weibin Chen Xuejie Xie Lihui Bai Yanxue Chen Shishou Kang Shishen Yan Yufeng Tian 《Advanced functional materials》2021,31(42):2105359
Fully electrical manipulation of magnetism, preferably through spin current, is highly desired to achieve energy-efficient, nonvolatile, and programmable spin logic devices. It is demonstrated in this study that in a single Pt/IrMn/Co/Ru/CoPt heterojunction, all 16 Boolean logic functions can be realized in a purely electrical way, relying on electrical manipulation of magnetic-field-free spin-orbit torque (SOT) switching. By applying current pulses along with two orthogonal directions, the exchange bias between IrMn and Co, and the SOT switching polarity (clockwise or counterclockwise) of perpendicularly magnetized CoPt, can be reversibly controlled, enabling complete spin logic within a single nonvolatile memory. This study makes a significant step towards practical electrical programmable spin logic devices. 相似文献