Low-Dimensional-Materials-Based Flexible Artificial Synapse: Materials, Devices, and Systems.

With the rapid development of artificial intelligence and the Internet of Things, there is an explosion of available data for processing and analysis in any domain. However, signal processing efficiency is limited by the Von Neumann structure for the conventional computing system. Therefore, the design and construction of artificial synapse, which is the basic unit for the hardware-based neural network, by mimicking the structure and working mechanisms of biological synapses, have attracted a great amount of attention to overcome this limitation. In addition, a revolution in healthcare monitoring, neuro-prosthetics, and human-machine interfaces can be further realized with a flexible device integrating sensing, memory, and processing functions by emulating the bionic sensory and perceptual functions of neural systems. Until now, flexible artificial synapses and related neuromorphic systems, which are capable of responding to external environmental stimuli and processing signals efficiently, have been extensively studied from material-selection, structure-design, and system-integration perspectives. Moreover, low-dimensional materials, which show distinct electrical properties and excellent mechanical properties, have been extensively employed in the fabrication of flexible electronics. In this review, recent progress in flexible artificial synapses and neuromorphic systems based on low-dimensional materials is discussed. The potential and the challenges of the devices and systems in the application of neuromorphic computing and sensory systems are also explored.

Experimental investigation on characteristics of graphene acoustic transducers driven by electrostatic and electromagnetic forces.

Acoustic transducers with graphene film have high sensitivity and wide bandwidth of frequency response as receivers. However, they exist in transmitting mode with low radiation performance. We propose an effective approach to enhance radiation performance of the graphene acoustic transducer by embedding a coil in insulating layer, and investigate the characteristics of graphene acoustic transducers by experiments. A graphene acoustic transducer is designed and fabricated. The highest receiving sensitivity of the transducer is -30 dB. The output sound pressure level of the transducer is more than 3 dB on average in the range of 2 âˆ¼ 16 kHz compared without a coil. And the sound pressure level increases by 6 dB on average in the range of 40 âˆ¼ 45 kHz. These results demonstrate that the graphene transducer maintains high receiving performance, and also improves acoustic radiation performance, which greatly expands its application field.

Graphene acoustic transducers based on electromagnetic interactions.

Graphene acoustic transducers have high sensitivity in receiving mode. However, they are used in transmitting mode with low radiation performance. A graphene acoustic transducer with high sensitivity and radiation performance is proposed in this study. The transducer is composed of graphene diaphragm, an insulating layer embedded in a copper planar coil, and a bottom layer plated with copper. The proposed capacitive transducer is driven by electrostatic and electromagnetic excitation. The sensitivity and radiation performance of the transducer are analyzed by transceiver theory and simulation models. The results demonstrate that the proposed capacitive transducer has excellent acoustic performance with sensitivity of -42 dB and the sound pressure level of 106 dB at 4 kHz with a 20-turn coil that is more than doubled compared without a copper coil. In addition, the radiation performance of the transducer is discussed by the coil parameters including coil turns and coil current, which can provide a theoretical basis for further experiments.

An improved algorithm of temperature compensation for a near infrared multiple-acquisition system based on two-dimensional regression analysis.

The near infrared (NIR) spectroscopy analytical technique is one of the most advanced and promising tools in many domains. NIR acquisition is easily influenced by temperature, thereby affecting qualitative and quantitative analyses. In this paper, a temperature compensation model was established between NIR signals and output voltage values based on two-dimensional regression analysis. The effectiveness of the proposed compensation scheme was experimentally demonstrated by the measurement of six super luminescent diode sources at 293-313 K. The coefficient of variation was decreased 2-fold with this compensation algorithm. The results indicated that it was suitable for various NIR spectral acquisition systems with lower complexity and a higher signal-noise-ratio after being applied to an acousto-optic-tunable-filter system.

Digital human modeling and its applications: Review and future prospects.

OBJECTIVE: The digital human modeling combines information technology with bioscience, applied to analog study from DNA molecule and protein to cell and tissue, as well as organ. It has been widely implemented in various fields such as aviation, national defense, film and television, sports and medical treatment. This paper sorts relative research achievements and progress in recent years and summarizes issues and challenges of research work. The purpose of this paper is to provide references for the development of Digital Human Modeling. METHODS: Basing on the development plans proposed by Federation of American Scientists (FAS) and current theories, we sorted academic achievements and relative references since the beginning of the digital human concept until 2014 into four aspects, which were named as Visible Human, Virtual Physical Human, Virtual Physiological Human, and Intelligent Virtual Human. We collected information of data acquisition, data analysis and dataset establishment for Visible Human. We outlined the Virtual Physical Human references in four physical categories, including radiation, ultrasonic, electrics, and mechanics. For Virtual Physiological Human, relative researches related to the physiological and biochemical changes of human body were categorized in four aspects as gene molecules, cells, and organs. Relative researches of Virtual Brain Human were mainly concentrated on virtual human brain and virtual human control. RESULTS: According to the differences in investigations and applications requirements of Digital Human in all aspects, we classified, analyzed and concluded extensive preference data. The overall plan of Digital Human, as well as technical routes, work plans, present states, goals, results and application value in each stage of research was summarized. We discussed the technical issues existing in each aspect of Digital Human, along with the urgent key technologies including data collection, data processing, and modeling. CONCLUSION: Analyzing the core technologies and the general technical schemes in the field of Digital Human, this paper summarizes the technical solutions, research results and technical problems of major researchers. The future prospects of Digital Human are reviewed.