Browsing by Subject "'current"

In this paper, the design issues of antenna-in-package (AiP) is discussed to modularize arrays at millimeter-wave (mmW) frequencies for 5G applications. The current progress of AiP technologies at NTU is also summarized. The issues of considerations include different fabrication process, dielectric property deviation and mechanical limitations to realize the antenna structure. Antenna designs for various applications, ranging from user equipment, CPE to small cell BTS antennas, have been developed at different sizes. The radiation characteristics of these AiPs will be presented to demonstrate the behaviors of AiPs using these processes. Both full-wave simulations and experimental measurements will be presented to validate the AiP designs. ? 2021 Taiwan Microwave Association.

This review overviewed the current researches on the isolation of novel strains, the development of novel identification protocols, the key enzymes and their synergistic interactions with other functional enzyme systems, and the strategies for enhancing enzymolysis efficiencies. The main obstacle for realizing biorefinery of lignocellulosic biomass to biofuels or biochemicals is the high cost of enzymolysis stage. Therefore, research prospects to reduce the costs for lignocellulose hydrolysis were outlined. ? 2021 Elsevier Ltd

This study simulates and compares symmetric and asymmetric MoS2 nanosheet transistor structures. The results show that the asymmetric MoS2 nanosheet transistor achieves higher current density and better gate control, and thus, this structure is optimized to meet the current density requirement for low-power applications in the International Roadmap for Devices and Systems (IRDS). Dielectric materials of Al2O3 and HfO2 are investigated, and equivalent oxide thicknesses ranging from 0.8 to 2 nm are analyzed. Transistors with Al2O3 as the dielectric exhibit better performance than those with HfO2 due to the lower level of remote phonon scattering. The gate length and underlap region are scaled down from 14 to 5 nm and from 7 to 1 nm, respectively, in an attempt to further enhance the ON-current. The substoichiometric metal oxide AlOx is used to induce more electrons in the undoped MoS2 channel. AlOx increases the ON-current with no gate control degradation. After optimization, the transistor demonstrates a subthreshold swing of 62.3 mV/dec, a drain-induced barrier lowering (DIBL) of 21.6 mV/dec, and a current density of $495 ~\mu \text{A}/\mu \text{m}$ with a supply voltage of 0.65 V. Compared with Si gate-all-around transistors, the MoS2 nanosheet transistor exhibits excellent gate control, good electrostatics, and comparable current density. ? 1963-2012 IEEE.

Excess nutrient uptake is one of the main factors of complications related to metabolism disorders. Therefore, efforts have emerged to modulate nutrient transport in the intestine. However, current approaches are mainly invasive interventions with various side effects. Here, a pH-responsive hydrogel is formulated by acidifying the hydroxide compounds within sucralfate to allow electrostatic interactions between pectin and aluminum ions. The pH responsiveness relies on the alternation of cations and hydroxide species, providing reversible shifting from a hydrogel to a complex coacervate system. It acts as a transient physical barrier coating to inhibit intestinal absorption and changes the viscosity and barrier function in different parts of the gastrointestinal tract, showing enhanced mucoadhesive properties. The therapeutic hydrogel remarkably lowers the immediate blood glucose response by modulating nutrient contact with bowel mucosa, suggesting potential in treating diabetes. In addition, it significantly reduces weight gain, fat accumulation, and hepatic lipid deposition in rodent models. This study provides a novel strategy for fabricating pH-responsive hydrogels, which may serve as a competent candidate for metabolism disorder management. ?

Action recognition is an important research field that has many applications in surveillance, video search, autonomous vehicles, etc. However, current state-of-the-art action classifiers are still not widely adopted in embedded applications yet. The major reason is that action recognition needs to process both spatial and temporal streaming data to precisely identify actions, which is compute- intensive and power hungry. To solve this issue, researchers start using FPGA to run action recognition models with minimum power. In this paper, we propose a new hardware architecture of action recognition on FPGA. Our model is based on the popular two-stream neural network. By optimizing the optical flow and convolution operations in the temporal domain, our method can achieve similar accuracy with one order of magnitude less operations than other C3D baseline models. We have implemented our model on Xilinx Ultrascale+ ZCU102 and released the source code. ? 2021 IEEE.

Biomass recalcitrance hinders efficient utilization of lignocellulosic biomass, making pretreatment process a crucial step for successful biorefinery process. Pretreatment processes have been developed for processing biomass, while technical obstacles including intensive energy requirement, high operational cost, equipment corrosions resulted from currently applied techniques promote the development of new pretreatment process for biomass. The deep eutectic solvent (DES) has been recognized as a promising solvent for biomass pretreatment, although the DES application toward biomass is still in its nascent stage. This review summarized the current researches using DES for biomass pretreatment, focusing particularly on lignin extraction and saccharification enhancement of lignocellulosic biomass. The mechanisms for biomass fractionation using DES as agents are introduced. Prospect and challenge were outlined. ? 2021 Elsevier Ltd

Current probabilistic flow-size monitoring can only detect heavy hitters (e.g., flows utilizing 10 times their permitted bandwidth), but cannot detect smaller overuse (e.g., flows utilizing 50-100 % more than their permitted bandwidth). Thus, these systems lack accuracy in the challenging environment of high-Throughput packet processing, where fast-memory resources are scarce. Nevertheless, many applications rely on accurate flow-size estimation, e.g., for network monitoring, anomaly detection and Quality of Service. We design, analyze, implement, and evaluate LOFT, a new approach for efficiently detecting overuse flows that achieves dramatically better properties than prior work. LOFT can detect 1.50x overuse flows in one second, whereas prior approaches can only reliably detect flows that overuse their allocation by at least 3x. We demonstrate LOFT's suitability for high-speed packet processing with implementations in the DPDK framework and on an FPGA. ? 2021 IEEE.

We design a Multi-Layer Aggregate Verification (MLAV) solution to improve supply chain management with IoT Blockchain devices. We apply MLAV to IoT Blockchain applications in Agriculture 4.0 to demonstrate the feasibility of our solutions and models. In the current Agriculture 4.0 structure, large companies have successfully applied blockchain solutions and ecosystems for tracking and tracing agricultural produce, achieving transparency, traceability, and digitalization. However, these existing blockchain solutions are not comprehensive. First, the upstream nodes they serve are all large-scale production suppliers, and smallholders are not taken into consideration. In order to solve this problem, we use a multi-layer architecture that serves three purposes: facilitating smallholders in joining the agricultural blockchain as equal-opportunity nodes, uploading of production activity data, and reducing costs (ex. Ethereum gas fee). Second, the majority of IoT blockchains adopt an ID-based signature scheme in IoT devices, which frequently has lower efficiency. In applying aggregate verification, we may effectively increase ID-based verification efficiency while processing large clusters of data transferred by IoT devices. Finally, we design a blockchain management framework using smart contracts to facilitate the financing of upstream producers. ? 2021 IEEE.

The switching of “ON” and “OFF” states of an ionic diode is investigated by considering a conical nanopore partially functionalized two polyelectrolyte (PE) layers via layer-by-layer deposition. Through observing the inversion of its rectification behavior, we demonstrate the function of the PE bilayers in ionic transport regulation. The ionic diode exhibits an ultrahigh ion rectification at a low level of pH. In an aqueous NaCl solution at pH 2, for example, the ratio of the current at “ON” state and that at “OFF” state can be about 800 and 200 for 1 and 100 mM, respectively. This remarkable gating behavior can be explained by the anion-pump-induced ion accumulation in the neutral region as well as the depletion zone at the interface. Our results further demonstrate the possibility of achieving an ultrahigh rectification in an ionic diode having a unipolar-like configuration. ? 2021 American Chemical Society

Aromatic compounds are important fuels and key chemical precursors for organic synthesis, however the current aromatics market are mainly relying on fossil resources which will eventually contribute to carbon emissions. Lignin has been recognized as a drop-in substitution to conventional aromatics, with its values gradually realized after tremendous research efforts in the recent five years. To facilitate the development of a possible lignin economics, this study overviewed the recent advances of various biorefinery techniques and the remaining challenging for lignin valorization. Starting with recent discovery of unexplored lignin structures, the potential functions of lignin related chemical structures were emphasized. The important breakthrough of lignin-first pretreatment, catalytic lignin depolymerization, and the high value products with possible benchmark with modern aromatics were reviewed with possible future targets. Possible retrofit of conventional petroleum refinery for lignin products were also introduced and hopefully paving a way to progressively migrate the industry towards carbon neutrality. ? 2021 Elsevier Ltd

A reconfigurable differential-to-single-ended autonomous current adaptation buffer amplifier (ACABA) suitable for biomedical applications is proposed. The ACABA, based on floating-gate technologies, is a capacitive circuit, of which output DC level and bandwidth can be adjusted by programming charges on floating nodes. The gain is variable by switching different amounts of capacitors without altering the output DC level. Without extra sensing and control circuitries, the current consumption of the proposed ACABA increases spontaneously when the input signal is fast or large, achieving a high slew rate. The supply current dwindles back to the low quiescent level autonomously when the output voltage reaches equilibrium. Therefore, the proposed ACABA is power-efficient and suitable for processing physiological signals. A prototype ACABA has been designed and fabricated in a 0.35m CMOS process occupying an area of 0.151 mm². When loaded by a 10 pF capacitor, it consumes 3 W to achieve a unity-gain bandwidth of 100 kHz with a measured IIP2 value of 52.66 dBV and a slew rate of 7.86 V/s. IEEE

The evolution of Cyber-Physical Systems (CPSs) and Internet of Things (IoTs) enables mobile and smart embedded devices to be equipped with embedded GPUs for accelerating data-intensive applications. To cut down device prices and reduce energy consumption, current GPUs adopt the unified memory architecture to extend memory size with using the PCIe SSD which is cheaper than directly enlarging the off-chip DRAM on the GPU. However, adopting the unified memory architecture, data shall be moved to the host DRAM before being moved to the off-chip DRAM and thus it leads to serious contention issues among CPUs and GPUs on the host DRAM. Although the advent of new communication technology provides the opportunity for GPUs to directly access the PCIe SSD without passing the host DRAM, it leads to high data movement costs because the latency gap between the off-chip DRAM and the PCIe SSD is large. To enhance the performance of the low-cost energy-efficient GPU memory systems, this work advocates a hardware-controller-based memory extension solution to not only avoid the contention issues on the host DRAM but also reduce the data movement costs. Particularly, we propose a scheduling-aware prefetching design to perform data prefetching by utilizing the information from the hardware warp scheduler. The proposed solution was evaluated by a series of intensive experiments and the results are encouraging. ? 2021 IEEE.

Devastating Japan in October 2019, Supertyphoon (STY) Hagibis was an important typhoon in the history of the Pacific. A striking feature of Hagibis was its explosive rapid intensification (RI). In 24 h, Hagibis intensified by 100 knots (kt; 1 kt ? 0.51 m s-1), making it one of the fastest-intensifying typhoons ever observed. After RI, Hagibis's intensification stalled. Using the current typhoon intensity record holder, i.e., STY Haiyan (2013), as a benchmark, this work explores the intensity evolution differences of these two high-impact STYs. We found that the extremely high prestorm sea surface temperature reaching 30.5°C, deep/warm prestorm ocean heat content reaching 160 kJ cm-2, fast forward storm motion of ?8 m s-1, small during-storm ocean cooling effect of ?0.5°C, significant thunderstorm activity at its center, and rapid eyewall contraction were all important contributors to Hagibis's impressive intensification. There was 36% more air-sea flux for Hagibis's RI than for Haiyan's. After its spectacular RI, Hagibis's intensification stopped, despite favorable environments. Haiyan, by contrast, continued to intensify, reaching its record-breaking intensity of 170 kt. A key finding here is the multiple pathways that storm size affected the intensity evolution for both typhoons. After RI, Hagibis experienced a major size expansion, becoming the largest typhoon on record in the Pacific. This size enlargement, combined with a reduction in storm translational speed, induced stronger ocean cooling that reduced ocean flux and hindered intensification. The large storm size also contributed to slower eyewall replacement cycles (ERCs), which prolonged the negative impact of the ERC on intensification. ? 2021 American Meteorological Society.

Metal-organic frameworks (MOFs) are an emerging class of materials for membrane gas separations. The pore limiting diameter (PLD) of a MOF, i.e., the aperture size of the material, is often used as a key structural property to evaluate its size exclusion capability for a gas mixture. The current computation of a PLD is based on the van der Waals radii outlined by the Cambridge Crystallographic Data Centre (CCDC), and this set of van der Waals radii may fail to capture the strong repulsion exerting on a guest molecule when passing through the bottleneck of a channel. In this work, we propose a new set of van der Waals radii for the framework atoms, whose values are smaller than the existing ones to describe the repulsive adsorbent-adsorbate interaction. The PLD of a MOF computed using this more transport-relevant radius set is referred to as PLDt-r, and that computed based on the widely used set outlined by CCDC is referred to as PLDCCDC. We evaluate the relevance between PLDt-r/PLDCCDC and the transport properties of MOF compounds including their diffusivity as well as diffusive and permeative selectivities for various binary mixtures. From our investigation on approximately 400 MOF structures, the results show that PLDt-r can more effectively identify highly selective MOFs for membrane gas separations. In this work, we also demonstrate the applicability of PLDt-r when the framework flexibility is considered. ? 2021 American Chemical Society.