Transmission Of Spatial Information Research Articles

Wavelength-polarization-multiplexed multichannel perfect vortex array generator based on dielectric metasurface

The multi-channel perfect vortex (PV) array based on metasurface has important applications in optical communication, particle manipulation, quantum optics, and other fields due to its ultra-thin structure and excellent wavefront control ability. However, it is very challenging to utilize a single metasurface to simultaneously achieve independent channel PV arrays at different wavelengths with low crosstalk and low structural complexity. Here, we propose and design a single rectangular structured metasurface based on TiO2, achieving a multi-channel PV beam array with dual-wavelength and dual-polarization multiplexing. Simulation and experimental results show that when two orthogonal linearly polarized beams with wavelengths of 532 nm and 633 nm are incident on the metasurface, clear PV arrays with corresponding topological charge arrangements can be obtained in different diffraction regions of the same observation plane. The metasurface proposed in this article can enhance the channel capacity of a PV beam array through wavelength-polarization-multiplexing, thus having important application potential in spatial information transmission, high-dimensional information storage, and secure information encryption.

Spatial pilot-aided fast-adapted framework for stable image transmission over long multi-mode fiber.

Multi-mode fiber (MMF) has emerged as a promising platform for spatial information transmission attributed to its high capacity. However, the scattering characteristic and time-varying nature of MMF pose challenges for long-term stable transmission. In this study, we propose a spatial pilot-aided learning framework for MMF image transmission, which effectively addresses these challenges and maintains accurate performance in practical applications. By inserting a few reference image frames into the transmitting image sequence and leveraging a fast-adapt network training scheme, our framework adaptively accommodates to the physical channel variations and enables online model update for continuous transmission. Experimented on 100 m length unstable MMFs, we demonstrate transmission accuracy exceeding 92% over hours, with pilot frame overhead around 2%. Our fast-adapt learning scheme requires training of less than 2% of network parameters and reduces the computation time by 70% compared to conventional tuning approaches. Additionally, we propose two pilot-insertion strategies and elaborately compare their applicability to a wide range of scenarios including continuous transmission, burst transmission and transmission after fiber re-plugging. The proposed spatial pilot-aided fast-adapt framework opens up the possibility for MMF spatial transmission in practical complicated applications.

Пространственная локализация цифрового звука в научном эксперименте и практике

<p style="text-align: justify;">Localization of sound in space is an important component of auditory perception, which is involved in the selection of various sound streams, the perception of speech in noise, and the organization of auditory images. Research over the past century has shown that sound localization is achieved through: differences in the intensity and time delay of sound waves arriving at different ears; spectral distortions arising from the anatomical features of the structure of the auricles, head, torso; dynamic cues (listener head movements), etc. However, some scientific and methodological issues (primarily related to the perception of natural sounds and the ecological validity of studies) have not been resolved. The development of digital audio techniques also leads to the emergence of new areas of research, including the processing of sound for the transmission of spatial information in headphones (which is solved using the head related transfer function — HRTF) and the creation of auditory interfaces. The tasks facing researchers in these areas are to improve the perception of spatial information (by manipulating the characteristics of the sound, prompts or training) and the creation of such sound events that can be perceived as object-related, i.e., inextricably linked with the purpose of the operator's activity. The methodology of the perceived quality of events, which makes it possible to distinguish which properties of the auditory image become the most important in human activity and which physical properties of the event they correspond to, can help in solving the tasks set and increasing the ecological validity of research.</p>

Research on spatial information transmission efficiency and capability of safety evacuation signs

Fires in buildings are among the high-frequency disasters experienced in urban areas. Improving the efficiency of emergency evacuation during fires can effectively reduce casualties. Safety evacuation signs offer indispensable spatial direction information for emergency evacuation, and the spatial relationship between safety signs and evacuees affects response times as well as evacuation efficiency. The research presented in this paper took two kinds of safety evacuation signs—namely, hangtag-type and embedded—as the research object, and a simulation experiment and fire drill were designed to gauge the transfer efficiency and capability of the spatial direction information they conveyed. The results show that the space angle of the hangtag-type safety evacuation sign was inversely proportional to the transfer efficiency and capability of the spatial direction information, and a fire drill confirmed this conclusion. When the spatial angle of the embedded safety evacuation sign was 5° the transfer efficiency and capability of the spatial direction information increased, the participants in the fire drill took less time, on average, to escape, and a higher percentage chose unfamiliar exits. In addition, three-dimensional safety evacuation signs were designed on the basis of the research results, and their functional structure was improved, which can make fire emergency evacuation more efficient.

Spatial observation of highly directional radiation from a compact 3D photonic-crystal antenna in Ku band

A three-dimensional compact prototype of a photonic crystal directive antenna is constructed for beam steering and directional radiation in the microwave. Experiments demonstrate that the array of dielectric cylinders placed in a U-shape open metal cavity can be profitably exploited to act as a high-efficiency splitting directive antenna in particular modes. Highly directional radiation has been observed at the fundamental electromagnetic resonance of band edge crystal with a maximum gain of 20.73 dBi and an aperture efficiency of 49.77%. The side-lobes on the E-plane (yoz) are almost constrained in −20 dB benefitting from the band edge lattice-induced resonance on the H-plane (xoy), suppressing the effect of aperture diffraction, and retaining high directivity performance in space. The detected half-power beam widths on the E-plane and H-plane are 7.7° and 8.9°, respectively, agreeing well with the simulations. Different from traditional orientation approaches, the photonic crystal antenna delivers performance of high directivity gain with compact structure, facile preparation, low cost, and high efficiency, which make it suitable for spatial information transmission and modulation and offer potential applications in remote sensing and wireless communication.

Distributed Satellite Relay Cooperative Communication with Optimized Signal Space Dimension

With the increasingly obvious trend of satellite communication and network integration, especially the emergence of inter satellite links, the interconnection between space nodes has become the development trend and inevitable requirement of future space communication. However, problems, such as long communication distance, large transmission delay and loss, limited network resources and frequent switching of transmission links, limit the ability of spatial information transmission. Firstly, based on the idea of ring planning and design, this paper uses the joint design of beamforming between nodes to design the physical layer network coding in the relay to realize the reliable transmission of information. Secondly, according to the diversity of relay signal space resources and network node information exchange, a joint design method of relay compression matrix and node precoding vector is studied, which breaks through the existing configuration constraints. In this scheme, the computational complexity is reduced by compressing and precoding the matrix to ensure reliable decoding while obtaining spatial alignment gain and degrees of freedom. Simulated and real data results demonstrate the superiority and effectiveness of the proposed method.

Vehicle detection method for satellite videos based on enhanced vehicle features

Vehicle detection by satellite videos is important for urban intelligent traffic construction. A satellite videos vehicle detection method is proposed to solve the problems of the surrounding background and the vehicles having a similar color, and the low number of pixels occupied by vehicles. First, we design a weighted normalization sparse autoencoder network, highlighting the effective features and strengthening the expression of the vehicle features by introducing weighted normalization sparse autoencoders into the backbone. Second, we design a method for the early fusion of spatial information transmission, realizing the enhancement of spatial information in the deep feature map through atrous convolution. Finally, we propose K-means++ based on adjusted cosine similarity, stretching the anchor box size by introducing the adjusted cosine similarity calculation. The experimental results show that the average accuracy of this method in satellite videos vehicle detection reached 75.7%, and the recall rate reached 89.6%. This method can effectively detect vehicles in satellite videos, and the effect is significantly improved compared with other methods.

Research on Spatial Information Transmission Efficiency and Capability of Safe Evacuation Signs

As an indispensable spatial direction information indicator for emergency evacuation, the spatial relationship between safety evacuation signs and evacuees will affect the response time of evacuees and the evacuation efficiency. This paper takes 2 kinds of common safety evacuation signs, hangtag-type and embedded, as the research object and designs space direction information transmission efficiency and capability simulation experiment and fire drill, the efficiency and capability of spatial direction information transmission of safety evacuation signs are studied. The results show that the space angle of the hangtag-type safety evacuation sign is inversely proportional to the information transmission efficiency and capability of the space direction, and the fire drill also confirms this conclusion. When the spatial angle of the embedded safety evacuation sign is 5{\deg}, the spatial direction information transmission efficiency and capability increase. Simultaneously, the average escape time of the participants in the fire drill was lower, and the percentage of choosing unfamiliarity exports increased. The evolution of spatial angle has no significant effect on the intention of the response of subjects of different genders; when choosing the direction, males are more easily affected by the change of spatial angle than females; the confidence level of females' choice is more easily affected by spatial angle. In addition, according to the research results, the corresponding three-dimensional structure safety evacuation signs are designed. The functional structure of the safety evacuation signs is perfected, which can effectively improve the efficiency of fire emergency evacuation.

Accessing spatial knowledge networks with maps

ABSTRACT Currently, knowledge networks develop to establish common data spaces. A common data-space offers mutual exchange and reusability for data sources and their derived information and provides access to structured knowledge and even creates wisdom. The geospatial domain becomes included in those knowledge networks and, therefore, creates spatial knowledge networks. ‘Geospatial’ is moving from a special expert domain to a ‘normal’ common data source that is processed for specific data science use cases. Maps with their different levels of abstraction according to its transmission task may offer (1) strategies to enhance processing performance, due to its abstraction, (2) persistent references of map features throughout different scales (abstractions) and (3) improvement of the transmission of spatial information, which includes the transmission interfaces as well as geo-communication. This paper tries to identify new functions for maps in new developing application areas. For example, a ‘universal semantic structure of topographic content’ could help to establish relations/links across domains that only have their own feature keys. We try to set the scene of cartography in a common data-space and highlight some requirements in the world of spatial knowledge networks, which are needed for automatization, machine learning and AI. According to Gordon and de Souza location matters: ‘Mapping is not simply a mode of visualisation, but a “central organizational device for networked communications”, an adaptive interface through which users can access, alter and deploy an expansive database of information, and a platform to socialize spatial information through collective editing, annotations, discussion, etc.’ [Gordon, E., & de Souza e Silva, A. (2011). Net locality: Why location matters in a networked world. John Wiley & Sons, p. 28].

Ghost imaging in a Rician fading channel with additive random noise

The stability of the spatial information transmission in communication is very important, and the ghost imaging mechanism has shown advantages in resistance to the external interference factors and in the low-light detection. A Rician fading channel typically describes the environment with a direct path and an infinite number of multi-path scatters, and the channel quality could be directly reflected by the estimation of the Rician factor. We propose a theoretical model of ghost imaging in a Rician fading channel with additive random noise. By calculating the peak signal-to-noise ratio and the resolution, the impact of the path loss and the Rician distribution on the imaging quality are numerically investigated. In addition, the comparative studies between the traditional non-correlated imaging and ghost imaging under the same conditions are also discussed, and it is shown that ghost imaging technique presents higher robustness and longer transmission distance. Our results establish a link between communication channels and ghost imaging, and provide reference and guidance for the spatial information transmission through a Rician fading channel.

Impact of geography and culture on spatial relations

AbstractCommunicating about spatial relations is a day-to-day task throughout our life. We accomplish it so spontaneously and easily that it was thought for long that our own way of transmitting spatial information was universal. However, when anthropologists and linguists started to carry on detailed studies on ‘exotic’ cultures, they found that the verbal expression of even basic spatial relations may differ significantly from language to language. This article contributes to this line of research and focuses on the local factors, notably cultural and geographic, which interfere with the linguistic expression and the precise transmission of spatial information in a few Arabic and Dravidian languages.

A pathway for spatial memory encoding.

The medial prefrontal cortex has been shown to play a role for rodents in successful completion of tasks that require spatial memory, but the pathways responsible for the transmission of spatial information to the mPFC, and the nature and timing of such information, are unknown. Recently, Spellman, Rigotti, Ahmari, Fusi, Gogos, and Gordon (Nature, 522, 309-314, 2015) addressed these questions in an eloquent and ingenious series of experiments, which we review in the broader context of the neurobiology of spatial memory.

Interdependence of the Rad50 Hook and Globular Domain Functions

Rad50 contains a conserved Zn(2+) coordination domain (the Rad50 hook) that functions as a homodimerization interface. Hook ablation phenocopies Rad50 deficiency in all respects. Here, we focused on rad50 mutations flanking the Zn(2+)-coordinating hook cysteines. These mutants impaired hook-mediated dimerization, but recombination between sister chromatids was largely unaffected. This may reflect that cohesin-mediated sister chromatid interactions are sufficient for double-strand break repair. However, Mre11 complex functions specified by the globular domain, including Tel1 (ATM) activation, nonhomologous end joining, and DNA double-strand break end resection were affected, suggesting that dimerization exerts a broad influence on Mre11 complex function. These phenotypes were suppressed by mutations within the coiled-coil and globular ATPase domains, suggesting a model in which conformational changes in the hook and globular domains are transmitted via the extended coils of Rad50. We propose that transmission of spatial information in this manner underlies the regulation of Mre11 complex functions.

Reward Cues in Space: Commonalities and Differences in Neural Coding by Hippocampal and Ventral Striatal Ensembles

Forming place-reward associations critically depends on the integrity of the hippocampal-ventral striatal system. The ventral striatum (VS) receives a strong hippocampal input conveying spatial-contextual information, but it is unclear how this structure integrates this information to invigorate reward-directed behavior. Neuronal ensembles in rat hippocampus (HC) and VS were simultaneously recorded during a conditioning task in which navigation depended on path integration. In contrast to HC, ventral striatal neurons showed low spatial selectivity, but rather coded behavioral task phases toward reaching goal sites. Outcome-predicting cues induced a remapping of firing patterns in the HC, consistent with its role in episodic memory. VS remapped in conjunction with the HC, indicating that remapping can take place in multiple brain regions engaged in the same task. Subsets of ventral striatal neurons showed a "flip" from high activity when cue lights were illuminated to low activity in intertrial intervals, or vice versa. The cues induced an increase in spatial information transmission and sparsity in both structures. These effects were paralleled by an enhanced temporal specificity of ensemble coding and a more accurate reconstruction of the animal's position from population firing patterns. Altogether, the results reveal strong differences in spatial processing between hippocampal area CA1 and VS, but indicate similarities in how discrete cues impact on this processing.

Cell Shape and Negative Links in Regulatory Motifs Together Control Spatial Information Flow in Signaling Networks

The role of cell size and shape in controlling local intracellular signaling reactions, and how this spatial information originates and is propagated, is not well understood. We have used partial differential equations to model the flow of spatial information from the beta-adrenergic receptor to MAPK1,2 through the cAMP/PKA/B-Raf/MAPK1,2 network in neurons using real geometries. The numerical simulations indicated that cell shape controls the dynamics of local biochemical activity of signal-modulated negative regulators, such as phosphodiesterases and protein phosphatases within regulatory loops to determine the size of microdomains of activated signaling components. The model prediction that negative regulators control the flow of spatial information to downstream components was verified experimentally in rat hippocampal slices. These results suggest a mechanism by which cellular geometry, the presence of regulatory loops with negative regulators, and key reaction rates all together control spatial information transfer and microdomain characteristics within cells.

Spatial information transmission beyond a system’s diffraction limit using optical spectral encoding of the spatial frequency

We propose optical spectral encoding of an object's spatial frequencies as a means of transmitting, through a low-numerical-aperture optical system, spatial information with an instantaneous spatial frequency bandwidth wider than the optical system's diffraction-limited bandwidth. We validate this new superresolution approach experimentally and demonstrate one of its possible practical implementations - wide-field spectrally encoded imaging that is sensitive to nanometre-scale local variations in the microstructure of centimetre-scale samples.

The Effects of Communication Modality and Spatial Processing Load on Distributed Team Performance in a Simulated C2 Environment

The present study addressed the effects of communication modality and spatial processing load on team performance, workload, and situational awareness. Sixteen people served as paid participants in this study. Teams of two participants competed against a computer opponent in a RoboFlag simulation based on “capture–the–flag”. Participants either could or could not see their teammates' simulated vehicles during a trial, and they could send each other images or annotated images from their RoboFlag display. Results of the experiment indicated that team performance and situational awareness were increased, and team communication and workload were decreased when participants could see teammates' vehicles, and more limitedly, that transmission of spatial information between teammates is facilitated by the ability to communicate that information pictorially. Overall, results support the supposition that distributed team performance may be mediated by spatial processing load.

Spatial Sensitivity in the Dorsal Zone (Area DZ) of Cat Auditory Cortex

We compared the spatial sensitivity of neural responses in three areas of cat auditory cortex: primary auditory cortex (A1), the posterior auditory field (PAF), and the dorsal zone (DZ). Stimuli were 80-ms pure tones or broadband noise bursts varying in free-field azimuth (in the horizontal plane) or elevation (in the vertical median plane), presented at levels 20-40 dB above units' thresholds. We recorded extracellular spike activity simultaneously from 16 to 32 sites in one or two areas of alpha-chloralose-anesthetized cats. We examined the dependence of spike counts and response latencies on stimulus location as well as the information transmission by neural spike patterns. Compared with units in A1, DZ units exhibited more complex frequency tuning, longer-latency responses, increased prevalence and degree of nonmonotonic rate-level functions, and weaker responses to noise than to tonal stimulation. DZ responses also showed sharper tuning for stimulus azimuth, stronger azimuthal modulation of first-spike latency, and enhanced spatial information transmission by spike patterns, compared with A1. Each of these findings was similar to differences observed between PAF and A1. Compared with PAF, DZ responses were of shorter overall latency, and more DZ units preferred stimulation from ipsilateral azimuths, but the majority of analyses suggest strong similarity between PAF and DZ responses. These results suggest that DZ and A1 are physiologically distinct cortical fields and that fields like PAF and DZ might constitute a "belt" region of auditory cortex exhibiting enhanced spatial sensitivity and temporal coding of stimulus features.

Significance of Honeybee Recruitment Strategies Depending on Foraging Distance (Hymenoptera: Apidae: Apis mellifera)

The importance of the spatial information which is communicated in the Carnolian Race of the Western Honeybee, Apis mellifera carnica (Pollmann 1879) waggle dance relative to other cues used by bees in finding food sources was investigated. The efficiency of recruitment with and without transmission of direction information in the waggle dance was quantified using artificial, plentiful unscented food sources and hives which were turned to a horizontal position to disrupt orientation of dancing bees and thereby eliminate the spatial information from dances. Transmission of location information seems to improve recruitment effect particularly at large distances. Recruitment declines more rapidly with distance if dances are disoriented, and for large distances it takes a few hours before a foraging group is established. However, this shows that even without dance information, foragers manage to recruit some bees to their food source. This process, however, is so slow that by the time a group of recruits has reached the food source, it may not be worth exploiting any more. Transmission of spatial information thus is especially important if distant food sources which often change in nectar availability are exploited.

Transmission of spatial information in S-cone pathways.

The mosaics of S-cones and the neurons to which they are connected are relatively well characterized, so the S-cone system is a good vehicle for exploring how the sampling of the retinal image controls visual performance. We used an interferometer to measure the grating acuity of the S-cone system in the fovea and at a range of eccentricities out to 20 deg. We also developed a simple model observer that, by assuming only that cone pathways are noisy and that signals are subject to eccentricity-dependent postreceptoral pooling, predicts the measured acuities from the sampling properties of the S-cone mosaic. The amount of pooling required to explain performance is consistent with that suggested by anatomical and physiological measurements.