TiN Nanoparticles for Enhanced THz Generation in TDS Systems

By virtue of the surface plasmon resonance effect, plasmonic nanoparticles (NPs) can localize the light field and significantly enhance the performance of some optoelectronic devices. In this work, NPs are employed for an enhanced generation of terahertz radiation from LT-GaAs-based antennas. Therefore, we have prepared plasmonic TiN NPs by direct ultrasonication (ULS) and pulsed laser ablation (PLA) techniques. The zeta potential, particle size, and absorbance were used to characterize the NPs in their colloidal forms in a comparison to commercial Au NPs. A layer of polydispersed titanium nitride (TiN) NPs prepared by PLA and deposited on the surface of an LT-GaAs device shows a significant improvement of terahertz signal generation from these devices with an enhancement of the peak to peak amplitude of 100%.     

Self-Assembled Perovskite Nanoislands on CH3NH3PbI3 Cuboid Single Crystals by Energetic Surface Engineering

Organometal perovskite single crystals have been recognized as a promising platform for high-performance optoelectronic devices, featuring high crystallinity and stability. However, a high trap density and structural nonuniformity at the surface have been major barriers to the progress of single crystal-based optoelectronic devices. Here, the formation of a unique nanoisland structure is reported at the surface of the facet-controlled cuboid MAPbI₃ (MA = CH₃NH₃⁺) single crystals through a cation interdiffusion process enabled by energetically vaporized CsI. The interdiffusion of mobile ions between the bulk and the surface is triggered by thermally activated CsI vapor, which reconstructs the surface that is rich in MA and CsI with reduced dangling bonds. Simultaneously, an array of Cs-Pb-rich nanoislands is constructed on the surface of the MAPbI₃ single crystals. This newly reconstructed nanoisland surface enhances the light absorbance over 50% and increases the charge carrier mobility from 56 to 93 cm² V⁻¹ s⁻¹. As confirmed by Kelvin probe force microscopy, the nanoislands form a gradient band bending that prevents recombination of excess carriers, and thus, enhances lateral carrier transport properties. This unique engineering of the single crystal surface provides a pathway towards developing high-quality perovskite single-crystal surface for optoelectronic applications.     

Data-parallel intra decoding for block-based image and video coding on massively parallel architectures

With the increasing number of processor cores available in modern computing architectures, task or data parallelism is required to maximally exploit the available hardware and achieve optimal processing speed. Current state-of-the-art data-parallel processing methods for decoding image and video bitstreams are limited in parallelism by dependencies introduced by the coding tools and the number of synchronization points introduced by these dependencies, only allowing task or coarse-grain data parallelism. In particular, entropy decoding and data prediction are bottleneck coding tools for parallel image and video decoding. We propose a new data-parallel processing scheme for block-based intra sample and coefficient prediction that allows fine-grain parallelism and is suitable for integration in current and future state-of-the-art image and video codecs. Our prediction scheme enables maximum concurrency, independent of slice or tile configuration, while minimizing synchronization points. This paper describes our data-parallel processing scheme for one- and two-dimensional prediction and investigates its application to block-based image and video codecs using JPEG XR and H.264/AVC Intra as a starting point. We show how our scheme enables faster decoding than the state-of-the-art wavefront method with speedup factors of up to 21.5 and 7.9 for JPEG XR and H.264/AVC Intra coding tools respectively. Using the H.264/AVC Intra coding tool, we discuss the requirements of the algorithm and the impact on decoded image quality when these requirements are not met. Finally, we discuss the impact on coding rate in order to allow for optimal parallel intra decoding.     

Using an eye tracker for accurate eye movement artifact correction

We present a new method to correct eye movement artifacts in electroencephalogram (EEG) data. By using an eye tracker, whose data cannot be corrupted by any electrophysiological signals, an accurate method for correction is developed. The eye-tracker data is used in a Kalman filter to estimate which part of the EEG is of ocular origin. The main assumptions for optimal correction are summed and their validity is proven. The eye-tracker-based correction method is objectively evaluated on simulated data of four different types of eye movements and visually evaluated on experimental data. Results are compared to three established correction methods: Regression, Principal Component Analysis, and Second-Order Blind Identification. A comparison of signal to noise ratio after correction by these methods is given in Table II and shows that our method is consistently superior to the other three methods, often by a large margin. The use of a reference signal without electrophysiological influences, as provided by an eye tracker, is essential to achieve optimal eye movement artifact removal.     

Performance bounds for VDE-SAT R-Mode

There has been growing interest within the satellite navigation community in the possibility of delivering positioning and timing services from existing or emerging constellations of Low-Earth Orbit communication satellites. At the same time, the international maritime community has been investigating the potential use of communication signals transmitted from shore-based stations for positioning—a concept commonly referred to as ‘ranging mode’, or R-Mode. The driving force for these developments is the desire to reduce the reliance on traditional Global Navigation Satellite Systems (GNSS). One of the technologies being considered for use in R-Mode is the evolution of the Automatic Identification System (AIS) known as the Very High Frequency Data Exchange System (VDES). VDES has a terrestrial and a satellite component. The feasibility of using terrestrial VDES transmissions for ranging was studied in a previous publication by the authors. This paper builds on the previous study and extends its results to the satellite component of VDES. Statistical bounds on the ranging error are derived for all downlink waveforms currently being considered for use in satellite VDES and for several custom-designed transmission formats. The analysis supports the feasibility of using both the existing and custom waveforms in ranging applications and points to related trade-offs that will need to be considered in the design of satellite VDES R-Mode systems.     

On considering hierarchical modulation in the porting process of legacy waveforms to software defined radio

The novel software defined radio (SDR) technology allows taking the next step in the evolution of military tactical communications. SDRs allow military radio operators to change waveforms on-the-fly according to the mission needs. On the one hand, new wideband networking waveforms will offer new services like high data throughputs and mobile ad-hoc networking capabilities. On the other hand, legacy waveforms will ensure interoperability to legacy equipment in missions where both types of radios are deployed at the same time. In this article, we analyze if an added value can be provided to the operators at SDRs hosting an ‘enhanced’ legacy waveform. This enhancement shall be introduced such that interoperability to the legacy equipment is still guaranteed. The modern concept of hierarchical modulation allows fulfilling this side constraint. While the legacy waveform acts as base-layer, some enhancement-layers offer extra bit budget to transmit additional information. This spare bit budget can be exploited to increase the data rate (i.e. throughput), the error robustness (and with this communication range), or both.     

LDD工艺参数对多晶硅薄膜晶体管KINK效应的影响

利用Tsuprem4和Medici软件,研究了多晶硅薄膜晶体管的LDD掺杂参数,如掺杂剂量、离子注入能量对KINK效应的影响,得到了它们之间的关系.计算结果表明,随着LDD掺杂剂量的变化,KINK效应对器件的影响是非线性的且存在一个最小值,在掺杂为2×1012cm-2时达到最小.而LDD掺杂能量对K1NK效应的影响是线性的,即随着离子注入能量的增加,KINK效应的影响变小.     

Adaptive bilateral filter for sharpness enhancement and noise removal.

In this paper, we present the adaptive bilateral filter (ABF) for sharpness enhancement and noise removal. The ABF sharpens an image by increasing the slope of the edges without producing overshoot or undershoot. It is an approach to sharpness enhancement that is fundamentally different from the unsharp mask (USM). This new approach to slope restoration also differs significantly from previous slope restoration algorithms in that the ABF does not involve detection of edges or their orientation, or extraction of edge profiles. In the ABF, the edge slope is enhanced by transforming the histogram via a range filter with adaptive offset and width. The ABF is able to smooth the noise, while enhancing edges and textures in the image. The parameters of the ABF are optimized with a training procedure. ABF restored images are significantly sharper than those restored by the bilateral filter. Compared with an USM based sharpening method-the optimal unsharp mask (OUM), ABF restored edges are as sharp as those rendered by the OUM, but without the halo artifacts that appear in the OUM restored image. In terms of noise removal, ABF also outperforms the bilateral filter and the OUM. We demonstrate that ABF works well for both natural images and text images.     

Low-voltage low-power fully-integratable automatic gain controls

This paper discusses the design of low-voltage low-power fully-integratable automatic gain controls. Four different AGCs are presented, all consisting of three elementary building blocks: a controlled amplifier, a comparator and a voltage follower. Their design is treated separately. As an example, the final section describes an automatic gain control for hearing instruments, realized in a bipolar process.