提供区别于传统的游戏思路和体验浅谈云游戏、体感游戏和VR游戏

云游戏,顾名思义,是以云计算为基础的游戏方式,游戏在服务器端运行并通过网络传输给远端的玩家.这个概念最早由Onlive公司于2009年提出,之后便有若干厂商开始跟进,2012年英伟达推出NVIDA GRID,2014年,SONY Playstation Now平台、微软Xbox云游戏、谷歌Stadia相继面世.可见这个...     

Biomimetic Bidirectional Switchable Adhesive Inspired by the Gecko

The gecko adhesive system has attracted significant attention since the discovery that van der Waals interactions, which are always present between surfaces, are predominantly responsible for their adhesion. The unique anisotropic frictional–adhesive capabilities of the gecko adhesive system originate from complex hierarchical structures and just as importantly, the anisotropic articulation of the structures. Here, by cleverly engineering asymmetric polymeric microstructures, a reusable switchable gecko‐like adhesive can be fabricated yielding steady high adhesion ( ≈ 1.25 N/cm²) and friction ( ≈ 2.8 N/cm²) forces when actuated for “gripping”, yet release easily with minimal adhesion ( ≈ 0.34 N/cm²) and friction (≈ 0.38 N/cm²) forces during detachment or “releasing”, over multiple attachment/detachment cycles, with a relatively small normal preload of 0.16 N/cm² to initiate the adhesion. These adhesives can also be used to reversibly suspend weights from vertical (e.g., walls), and horizontal (e.g., ceilings) surfaces by simultaneously and judiciously activating anisotropic friction and adhesion forces. This design opens the way for new gecko‐like adhesive surfaces and articulation mechanisms that do not rely on intensive nanofabrication in order to recover the anisotropic tribological property of gecko adhesive pads, albeit with lower adhesive forces compared to geckos.     

Tuning the optical absorption of potential blue emitters

The quest for more efficient blue emitters to be applied in organic light-emitting diodes is one of the challenging tasks of contemporary nanotechnologies. An approach to enhance substantially the intrinsic efficiency of luminescent organic molecules is the so-called thermally activated delayed fluorescence. A prerequisite for its occurrence is a vanishing energy separation between the first singlet and triplet excited states. A series of donor–acceptor molecules is investigated theoretically within this study in order to validate a molecular model for design of efficient organic blue emitters with closely spaced singlet and triplet excited states. The model is based on meta-linkage of the donor and acceptor residues to a spacer ensuring frontier molecular orbitals partitioning. The optimal geometries of the molecules are obtained with density functional theory (B3LYP/6-31G^*) and the singlet and triplet absorption spectra are simulated within the time-dependent density functional framework. The excited singlet-triplet energy gap is estimated and correlated to structural and energetic characteristics of the donors and acceptors. Several requirements for achieving high-energy triplet states at the molecular level in such donor–acceptor systems are outlined, the main being disjoint character of the molecular orbitals on the spacer and sufficient energy separation of the two topmost occupied orbitals. It is shown that by variation of the acceptor moiety the optical absorption transitions of the compounds can be fine-tuned in a systematic fashion. Molecules with degenerate singlet and triplet first excited states are proposed, combining bisdimethylaminotriphenylamine or phenoxazine as donors with diphenyloxadiazole or diphenyl-2,2′-bipyridine as acceptors. Bipolar molecules derived from this model could be used as prospective building blocks for efficient emissive materials in blue organic light-emitting diodes.     

Binary Cellulose Nanocrystal Blends for Bioinspired Damage Tolerant Photonic Films

Most attempts to emulate the mechanical properties of strong and tough natural composites using helicoidal films of wood‐derived cellulose nanocrystals (w‐CNCs) fall short in mechanical performance due to the limited shear transfer ability between the w‐CNCs. This shortcoming is ascribed to the small w‐CNC‐w‐CNC overlap lengths that lower the shear transfer efficiency. Herein, we present a simple strategy to fabricate superior helicoidal CNC films with mechanical properties that rival those of the best natural materials and are some of the best reported for photonic CNC materials thus far. Assembling the short w‐CNCs with a minority fraction of high aspect ratio CNCs derived from tunicates (t‐CNCs), we report remarkable simultaneous enhancement of all in‐plane mechanical properties and out‐of‐plane flexibility. The important role of t‐CNCs is revealed by coarse grained molecular dynamics simulations where the property enhancement are due to increased interaction lengths and the activation of additional toughening mechanisms. At t‐CNC contents greater than 5% by mass the mixed films also display UV reflecting behaviour. These damage tolerant optically active materials hold great promise for application as protective coatings. More broadly, we expect the strategy of using length‐bidispersity to be adaptable to mechanically enhancing other matrix‐free nanoparticle ensembles.     

Photolytic deposition of aluminum nitride and oxy-nitride films at temperatures ≤ 350k

Aluminum nitride and oxy-nitride thin films have been deposited on Si(100) substrates at temperatures of 300-350K by gas-phase excimer laser photolysis at 193 nm. The precursors used for this deposition process are trimethylamine alane and ammonia. The properties of these laser-deposited films were studied using scanning electron microscopy, energy dispersive x-ray analysis, and x-ray diffraction. X-ray photoelectron spectroscopy has been extensively used to provide information regarding the chemical compositions on the surface and in the bulk of these laser deposited films, as well as on the chemical states of the components of the films. Well-adhering, smooth, amorphous films of AlN are obtained at a substrate temperature of 350K using this technique.     

Data-delay evaluation in integrated wireless networks based on local product-form solutions for voice occupancy

In this paper we consider the evaluation of data-packet delay in wireless integrated voice/data networks. In networks that support voice in the classical circuit-switched fashion, the voice occupancy process satisfies a product-form solution under reasonable modeling assumptions. Although this product-form solution provides an accurate characterization of equilibrium voicetraffic behavior, it does not directly provide a method to evaluate data-packet delay. However, examination of each link separately in a manner that incorporates interaction with the rest of the network permits us to take advantage of the wireless nature of the network and obtain a three-flow characterization of each link, which also satisfies a product-form solution and is hence termed a mini-product-form solution. By matching the values of these flows to the average values obtained from the product-form solution of the entire network, we obtain a three-dimensional Markov chain characterization of the voice occupancy state on the link, which permits a simpler evaluation of data-packet delay. A further reduction is possible by converting the three-dimensional chain to a single-dimensional one. Performance results demonstrate that these models provide satisfactory delay estimates that also appear to be upper bounds on delay.C.M. Barnhart was at the Naval Research Laboratory when this paper was written.     

Performance Analysis of the Spectral Correlation Discriminator Array

Mobile communications suffer from cochannel interference, adjacent channel interference and fading. The cell capacity or the number of users per cell is limited by the interference. In this paper we analyze a new blind adaptive array structure called the spectral correlation discriminator array (SCDA), designed to reject cochannel interference for advanced mobile phone service (AMPS) signals. The blind adaptive array exploits the spectral redundancy in the AMPS signals which arises due to the presence of the supervisory audio tone (SAT). SCDA is shown to provide an improvement of 25–30 dB in signal-to-interference plus noise ratio (SINR) in static multipath channels and 10–15 dB improvement of SINR in Rayleigh fading channels. The SCDA is compared to the least squares constant modulus array (LSCMA) and is shown to have better signal selectivity properties. The reduction in interference power can significantly reduce the frequency reuse factor.     

Surface triangulation for 3-D scene model construction from stereo

The construction of an accurate 3-D scene model is a fundamental aspect of any model-based image coding scheme. This article describes the generation of a triangular facet surface representation from the data acquired by a calibrated binocular (stereo) camera system     

A shape memory polymer dialysis needle adapter for the reduction of hemodynamic stress within arteriovenous grafts

A deployable, shape memory polymer adapter is investigated for reducing the hemodynamic stress caused by dialysis needle flow impingement within an arteriovenous graft. Computational fluid dynamics simulations of dialysis sessions with and without the adapter demonstrate that the adapter provides a significant decrease in the wall shear stress. Preliminary in vitro flow visualization measurements are made within a graft model following delivery and actuation of a prototype shape memory polymer adapter. Both the simulations and the qualitative flow visualization measurements demonstrate that the adapter reduces the severity of the dialysis needle flow impingement on the vascular access graft.     

Sputtered ZnO seed layer enhances photovoltaic behavior in hybrid ZnO/P3HT solar cells

We investigated the characteristics of inverted solar cells comprising bulk-heterojunction active layers of ZnO nanowire arrays and poly(3-hexylthiophene), P3HT. By utilizing a sputtered ZnO seed layer, we are able to grow vertically oriented ZnO nanowire arrays homoepitaxially. Unlike the ZnO nanowires that are grown on sol–gel derived seed layers, our nanowires are more uniform in their dimensions and spatial distribution. This sputtered seed layer also acts as the hole-blocking layer when these nanowire arrays are incorporated in solar cells; hybrid solar cells comprising these nanowires and P3HT exhibit power conversion efficiencies of 1.6%. To date, this is the highest efficiency observed for ZnO nanowire arrays:P3HT hybrid solar cells.