Communications engineering最新文献

Origami structures hold promising potential in space applications, such as ultra-large-area solar arrays, deployable space stations, and extra-terrestrial modular foldable buildings. However, the development of thick-panel origami structures has been limited, relying on a few typical origami patterns without a comprehensive design theory for multi-crease, multi-vertex thick-panel configurations. Additionally, realizing closed Polyhedra in thick-panel origami presents substantial challenges. Here, we introduce a design methodology inspired by origami and kirigami principles for one-degree-of-freedom (one-DOF) flat-foldable thick-panel origami-kirigami structures, including modular scalable arrays and closed polyhedral structures. The thick-panel origami-kirigami modular scalable arrays incorporate mixed four-crease vertices and (2n + 4)-crease vertices, enabling one-DOF flat-foldability and modular expansion of thick-panel units. The thick-panel origami-kirigami closed polyhedral structures, including tetrahedrons, square pyramids and triangular prisms, possess one-DOF inward-flat-foldability and structural closure after unfolding. This novel design framework for thick-panel origami-kirigami structures is capable of structural design from centimeter to meter scale, validated by kinematic analysis and prototype experiments.

High quality imaging is required for high quality medical care, especially in precision applications such as radiation therapy. Patient motion during image acquisition reduces image quality and is either accepted or dealt with retrospectively during image reconstruction. Here we formalize a general approach in which data acquisition is treated as a spatiotemporal optimization problem to solve in real time so that the acquired data has a specific structure that can be exploited during reconstruction. We provide results of the first-in-world clinical trial implementation of our spatiotemporal optimization approach, applied to respiratory correlated 4D cone beam computed tomography for lung cancer radiation therapy (NCT04070586, ethics approval 2019/ETH09968). Performing spatiotemporal optimization allowed us to maintain or improve image quality relative to the current clinical standard while reducing scan time by 63% and reducing scan radiation by 85%, improving clinical throughput and reducing the risk of secondary tumors. This result motivates application of the general spatiotemporal optimization approach to other types of patient motion such as cardiac signals and other modalities such as CT and MRI.

The development of sixth-generation wireless communication systems demands innovative solutions to address challenges in the deployment of a large number of base stations and the detection of multi-band signals. Quantum technology, specifically nitrogen-vacancy centers in diamonds, offers promising potential for the development of compact, robust receivers capable of supporting multiple users. Here we propose a multiple access scheme using fluorescent nanodiamonds containing nitrogen-vacancy centers as nano-antennas. The unique response of each nanodiamond to applied microwaves allows for distinguishable patterns of fluorescence intensities, enabling multi-user signal demodulation. We demonstrate the effectiveness of our nanodiamonds-implemented receiver by simultaneously transmitting two uncoded digitally modulated information bit streams from two separate transmitters, achieving a low bit error ratio. Moreover, our design supports tunable frequency band communication and reference-free signal decoupling, reducing communication overhead. Furthermore, we implement a miniaturized device comprising all essential components, highlighting its practicality as a receiver serving multiple users simultaneously. This approach enables the integration of quantum sensing technologies into future wireless communication networks.

Within the context of neuromorphic computing, analog photonics, especially after the advent of photonic integrated technologies, offers unparalleled computing speeds per core, and the reduction of size and power consumption compared to digital electronics. However, the functionality of analog systems is limited by noise and non-linear distortions, which degrade signal resolution. Here, a method is presented for analyzing and minimizing the effect of non-linearities associated with the optical power transfer function of a generic modulator, to inform choices of design and operation conditions. The Mach-Zehnder interferometer, micro-ring modulator, and ring-assisted Mach-Zehnder interferometer are compared using this method. The analysis is applied to compare three analog photonic processor architectures for machine learning applications, based on wavelength, space, and time division multiplexing. Our results indicate that despite the lower maximum resolution exhibited by Mach-Zehnder interferometers, they are the most balanced choice for space and time division multiplexing architectures due to stability and power consumption.

Touchscreens are a fundamental technology for human society providing the primary gateway for human-machine interaction. Today's touchscreens can only be used to detect touch and provide the location of the user's touch input but not to simultaneously communicate digital data during a touch event through the touchscreen. If communication through a touchscreen can be enabled, it promises deep societal impact by augmenting the most popular Human-Computer-Interaction interface with new possibilities such as a single application on the same device opening up personalized user-specific account data depending on the person interacting with the application. Leveraging advances in Electro-Quasistatic field based communication in the past decade, we propose and demonstrate Touchscreen Communication (ToSCom), a high-speed (>Mbps) simultaneous communication and touch sensing interface. We develop a low path loss channel across the entire touchscreen surface enabling 3 Mbps data rate communication with an average bit-error-rate of less than 5 × 10^-7 through the touchscreen surface simultaneously during touch sensing. ToSCom enables a wide range of possibilities in day-to-day life like in wearable devices like transactions in a Point-of-Sale system, audio/image file transfer, and viewing personalized data in touchscreen kiosks.

Environmental problems are worsening due to the complexity in managing plastic waste. Chemical recycling emerges as a pivotal technology that can suppress carbon introduction into the carbon cycle and provide petroleum alternatives for current petrochemical processes. The utilization of zeolites can reduce energy consumption by lowering the operation temperature for pyrolysis. Here, we demonstrate low-temperature catalytic cracking of polyethylene (PE) utilizing an open-batch reactor configuration and *BEA-type zeolite catalysts. With the optimized open-batch setup and zeolites, high PE conversion (~80%) and liquid selectivity (~70%) were achieved at 330 °C. We systematically explored the effects of aluminum (Al) site density and crystal size, revealing that zeolite crystal size is another critical factor determining the liquid production. This work not only demonstrates that an effective combination and optimization of reactor and catalysts can enhance the overall catalytic activity but also offers insights into designing catalysis systems for effective recycling of polyolefin wastes.

As the demand for data capacity in wireless networks and mobile communications continues to grow, they are moving toward higher carrier frequencies and wider modulation bandwidths. Unfortunately, electronic device performance degrades in association with increased frequency and modulation bandwidths, which inhibits the application of conventional microwave architectures, particularly in the millimeter wave and terahertz regimes. Alternatively, microwave photonic systems address these challenges by offering device and system performance with exceptionally higher operational bandwidths. The challenge, however, is the ability to monolithically integrate both electronic and photonic devices into functional components that provide ultra-wideband performance up into the millimeter wave and terahertz regions. In particular, such integration remains a major technical challenge due to the high dielectric permittivity of commonly used material platforms for photonic integrated circuits, such as silicon, indium phosphide, and lithium niobate. In this paper, we present a photonic receiver consisting of a broadband antenna and a low-drive-voltage modulator monolithically integrated on thin-film lithium niobate with a quartz handle. A free-space data link is demonstrated, achieving data rates up to 2.7 Gbps using quadrature amplitude modulation, with error vector magnitude as low as 3%. This work demonstrates the potential of thin-film lithium niobate for high-frequency, monolithically integrated radiofrequency and photonic devices to enable ultra-wideband millimeter wave-to-terahertz communication systems.

The X-ray flux from X-ray free-electron lasers and storage rings enables new spatiotemporal opportunities for studying in-situ and operando dynamics, even with single pulses. X-ray multi-projection imaging is a technique that provides volumetric information using single pulses while avoiding the centrifugal forces induced by conventional time-resolved 3D methods like time-resolved tomography, and can acquire 3D movies (4D) at least three orders of magnitude faster than existing techniques. However, reconstructing 4D information from highly sparse projections remains a challenge for current algorithms. Here we present 4D-ONIX, a deep-learning-based approach that reconstructs 3D movies from an extremely limited number of projections. It combines the computational physical model of X-ray interaction with matter and state-of-the-art deep learning methods. We demonstrate its ability to reconstruct high-quality 4D by generalizing over multiple experiments with only two to three projections per timestamp on simulations of water droplet collisions and experimental data of additive manufacturing. Our results demonstrate 4D-ONIX as an enabling tool for 4D analysis, offering high-quality image reconstruction for fast dynamics three orders of magnitude faster than tomography.

Metalenses, with their ultrathin thicknesses and their ease for achieving ultra small diameters, offer a promising alternative to refractive lenses in miniaturized imaging systems, such as endoscopes, potentially enabling applications in tightly confined spaces. However, traditional metalenses suffer from strong chromatic aberrations, limiting their utility in multi-color imaging. To address this limitation, here we present an inverse-designed polychromatic metalens with a diameter of 680 μm, focal length of 400 μm, and low dispersion across 3 distinct wavelengths at 643 nm, 532 nm, and 444 nm. The metalens collimates and steers light emitted from a scanning fiber tip, generating scanning beams across a 70° field-of-view to provide illumination for a scan-based imaging. The metalens provides a close-to-diffraction-limited 0.5° angular resolution, only restricted by the effective aperture of the system. The average relative efficiency among three design wavelengths is around 32% for on-axis angle and 13% averaged across the entire field-of-view. This work holds promise for the application of metalenses in endoscopes and other miniaturized imaging systems.