The organization of behavior: A neuropsychological theory

This review article attempts to provide a comprehensive review of the recent progress in the so-called resistive random access memories (RRAMs) First, a brief introduction is presented to describe the construction and development of RRAMs, their potential for broad applications in the fields of nonvolatile memory, unconventional computing and logic devices, and the focus of research concerning RRAMs over the past decade Second, both inorganic and organic materials used in RRAMs are summarized, and their respective advantages and shortcomings are discussed Third, the important switching mechanisms are discussed in depth and are classified into ion migration, charge trapping/de-trapping, thermochemical reaction, exclusive mechanisms in inorganics, and exclusive mechanisms in organics Fourth, attention is given to the application of RRAMs for data storage, including their current performance, methods for performance enhancement, sneak-path issue and possible solutions, and demonstrations of 2-D and 3-D crossbar arrays Fifth, prospective applications of RRAMs in unconventional computing, as well as logic devices and multi-functionalization of RRAMs, are comprehensively summarized and thoroughly discussed The present review article ends with a short discussion concerning the challenges and future prospects of the RRAMs

Recent progress in resistive random access memories: Materials, switching mechanisms, and performance

Science and technologies based on terahertz frequency electromagnetic radiation (100 GHz–30 THz) have developed rapidly over the last 30 years. For most of the 20th Century, terahertz radiation, then referred to as sub-millimeter wave or far-infrared radiation, was mainly utilized by astronomers and some spectroscopists. Following the development of laser based terahertz time-domain spectroscopy in the 1980s and 1990s the field of THz science and technology expanded rapidly, to the extent that it now touches many areas from fundamental science to 'real world' applications. For example THz radiation is being used to optimize materials for new solar cells, and may also be a key technology for the next generation of airport security scanners. While the field was emerging it was possible to keep track of all new developments, however now the field has grown so much that it is increasingly difficult to follow the diverse range of new discoveries and applications that are appearing. At this point in time, when the field of THz science and technology is moving from an emerging to a more established and interdisciplinary field, it is apt to present a roadmap to help identify the breadth and future directions of the field. The aim of this roadmap is to present a snapshot of the present state of THz science and technology in 2017, and provide an opinion on the challenges and opportunities that the future holds. To be able to achieve this aim, we have invited a group of international experts to write 18 sections that cover most of the key areas of THz science and technology. We hope that The 2017 Roadmap on THz science and technology will prove to be a useful resource by providing a wide ranging introduction to the capabilities of THz radiation for those outside or just entering the field as well as providing perspective and breadth for those who are well established. We also feel that this review should serve as a useful guide for government and funding agencies.

The 2016 terahertz science and technology roadmap

https://www.repository.cam.ac.uk/bitstream/1810/264501/1/Fu_et_al-2017-Progress_in_Material_Science-VoR.pdf

Advances in piezoelectric thin films for acoustic biosensors, acoustofluidics and lab-on-chip applications

The optimization field suffers from the metaphor-based “pseudo-novel” or “fancy” optimizers. Most of these cliche methods mimic animals' searching trends and possess a small contribution to the optimization process itself. Most of these cliche methods suffer from the locally efficient performance, biased verification methods on easy problems, and high similarity between their components' interactions. This study attempts to go beyond the traps of metaphors and introduce a novel metaphor-free population-based optimization method based on the mathematical foundations and ideas of the Runge Kutta (RK) method widely well-known in mathematics. The proposed RUNge Kutta optimizer (RUN) was developed to deal with various types of optimization problems in the future. The RUN utilizes the logic of slope variations computed by the RK method as a promising and logical searching mechanism for global optimization. This search mechanism benefits from two active exploration and exploitation phases for exploring the promising regions in the feature space and constructive movement toward the global best solution. Furthermore, an enhanced solution quality (ESQ) mechanism is employed to avoid the local optimal solutions and increase convergence speed. The RUN algorithm's efficiency was evaluated by comparing with other metaheuristic algorithms in 50 mathematical test functions and four real-world engineering problems. The RUN provided very promising and competitive results, showing superior exploration and exploitation tendencies, fast convergence rate, and local optima avoidance. In optimizing the constrained engineering problems, the metaphor-free RUN demonstrated its suitable performance as well. The authors invite the community for extensive evaluations of this deep-rooted optimizer as a promising tool for real-world optimization. The source codes, supplementary materials, and guidance for the developed method will be publicly available at different hubs at http://imanahmadianfar.com and http://aliasgharheidari.com/RUN.html .

RUN beyond the metaphor: An efficient optimization algorithm based on Runge Kutta method

This paper presents our investigation into a 220 GHz multicarrier high-speed communication system based on solid state transceivers. The proposed system has eased the demand of high sampling rate analog-to-digital converter (ADC) by providing several signal carriers in microwave band and converting them to 220 GHz channel. The system consists of a set of 220 GHz solid-state transceiver with 2 signal carriers, two base-bands for 4 GSPS ADCs. It has achieved 12.8 Gbps rate real-time signal transmission using 16QAM modulation over a distance of 20 m without any other auxiliary equipment or test instruments. The baseband algorithm overcomes the problem of frequency difference generates by non-coherent structure, which guarantees the feasibility of long-distance transmission application. Most importantly, the proposed system has already carried out multi-channel 8K video parallel transmission through switch equipment, which shows the multicarrier high-speed communication system in submillimeter wave has great application prospects. To the best of the authors' knowledge, this is the first all-solid-state electronics multicarrier communication system in submillimeter and terahertz band.

The research on 220GHz multicarrier high-speed communication system

X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy are used to study Si nanocrystal formation in Si-implanted SiO2 films as a function of thermal annealing. Analysis of the XPS Si 2p peaks shows the existence of five chemical structures corresponding to the Si oxidation states Sin+ (n = 0, 1, 2, 3, and 4) in the SiO2 films, and the concentration of each oxidation state is determined quantitatively. The XPS results show a clear picture of the evolution of the chemical structures and the formation of Si nanocrystals as functions of annealing temperature and annealing time. The evolution of the concentrations of the five oxidation states with annealing is explained in terms of the thermal decompositions of the suboxides corresponding to the three oxidation states Sin+ (n = 1, 2, and 3) and the thermal oxidation of the implanted Si.

https://iopscience.iop.org/article/10.1088/0022-3727/36/19/L02/pdf

A study on Si nanocrystal formation in Si-implanted SiO2 films by x-ray photoelectron spectroscopy

Frequency multipliers and mixers based on Schottky barrier diodes (SBDs) are widely used in terahertz (THz) imaging applications. However, they still face obstacles, such as poor performance consistency caused by discrete flip-chip diodes, as well as low efficiency and large receiving noise temperature. It is very hard to meet the requirement of multiple channels in THz imaging array. In order to solve this problem, 12-μm-thick gallium arsenide (GaAs) monolithic integrated technology was adopted. In the process, the diode chip shared the same GaAs substrate with the transmission line, and the diode’s pads were seamlessly connected to the transmission line without using silver glue. A three-dimensional (3D) electromagnetic (EM) model of the diode chip was established in Ansys High Frequency Structure Simulator (HFSS) to accurately characterize the parasitic parameters. Based on the model, by quantitatively analyzing the influence of the surface channel width and the diode anode junction area on the best efficiency, the final parameters and dimensions of the diode were further optimized and determined. Finally, three 0.34 THz triplers and subharmonic mixers (SHMs) were manufactured, assembled, and measured for demonstration, all of which comprised a waveguide housing, a GaAs circuit integrated with diodes, and other external connectors. Experimental results show that all the triplers and SHMs had great performance consistency. Typically, when the input power was 100 mW, the output power of the THz tripler was greater than 1 mW in the frequency range of 324 GHz to 352 GHz, and a peak efficiency of 6.8% was achieved at 338 GHz. The THz SHM exhibited quite a low double sideband (DSB) noise temperature of 900~1500 K and a DSB conversion loss of 6.9~9 dB over the frequency range of 325~352 GHz. It is indicated that the GaAs monolithic integrated process, diodes modeling, and circuits simulation method in this paper provide an effective way to design THz frequency multiplier and mixer circuits.

Development of 340-GHz Transceiver Front End Based on GaAs Monolithic Integration Technology for THz Active Imaging Array

In this study, multilayer perceptron artificial neural networks are used to predict orthodontic treatment plans, including the determination of extraction-nonextraction, extraction patterns, and anchorage patterns. The neural network can output the feasibilities of several applicable treatment plans, offering orthodontists flexibility in making decisions. The neural network models show an accuracy of 94.0% for extraction-nonextraction prediction, with an area under the curve (AUC) of 0.982, a sensitivity of 94.6%, and a specificity of 93.8%. The accuracies of the extraction patterns and anchorage patterns are 84.2% and 92.8%, respectively. The most important features for prediction of the neural networks are “crowding, upper arch” “ANB” and “curve of Spee”. For handling discrete input features with missing data, the average value method has a better complement performance than the k-nearest neighbors (k-NN) method; for handling continuous features with missing data, k-NN performs better than the other methods most of the time. These results indicate that the proposed method based on artificial neural networks can provide good guidance for orthodontic treatment planning for less-experienced orthodontists.

/pdf/orthodontic-treatment-planning-based-on-artificial-neural-4c34l8ne15.pdf

Orthodontic Treatment Planning based on Artificial Neural Networks

Terahertz technology is a hotspot in the current academic research. In this study, a 400 GHz broadband multi-branch waveguide hybrid coupler is designed, but it is very difficult to fabricate. In order to release the processing difficulty, a modified five-branch hybrid coupler has also been designed, fabricated and measured. The hybrid coupler consists of five modified branches and has been optimised to a great performance, which increases the operation bandwidth. Compared to the traditional five-branch hybrid coupler design, this structure has a wider operation bandwidth and the bandwidth is almost the same as traditional seven-branch hybrid coupler. Based on this model, the performance of the coupler is optimised by HFSS software. The measurement results show good performance that >18 dB return loss (S
 11
) and isolation (S
 23
), 90° ± 2° phase difference and 0.3 dB amplitude imbalance are obtained in the frequency range of 380-460 GHz, agreeing well with the simulation results.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-map.2020.0090

Yang Liu

Papers

The research on 220GHz multicarrier high-speed communication system

A study on Si nanocrystal formation in Si-implanted SiO2 films by x-ray photoelectron spectroscopy

Development of 340-GHz Transceiver Front End Based on GaAs Monolithic Integration Technology for THz Active Imaging Array

Orthodontic Treatment Planning based on Artificial Neural Networks

Four‐hundred gigahertz broadband multi‐branch waveguide coupler