A Robust Mobile Robot Navigation System using Neuro-Fuzzy Kalman Filtering and Optimal Fusion of Behavior-based Fuzzy Controllers

This study proposes a control system model for mobile robots navigating in unknown environments. The proposed model includes a neuro-fuzzy Extended Kalman Filter for localization task and a behaviorbased fuzzy multi-controller navigation module. The neuro-fuzzy EKF, used for estimating the robot’s position from sensor readings, is an enhanced EKF whose noise covariance matrix is progressively adjusted by a fuzzy neural network. The navigation module features a series of independently-executed fuzzy controllers, each deals with a specific navigation sub-task, or behavior, and a multi-objective optimizer to coordinate all behaviors. The membership functions of all fuzzy controllers play the roles of objective functions for the optimizer, which produces an overall Pareto-optimal control signal to drive the robot. A number of simulations and real-world experiments were conducted to evaluate the performance of this model

Non-Regenerative Full Distributed Space-Time Codes in Cooperative Relaying Networks

International audienceDistributed space-time codes (DSTC) are often used in cooperative relaying networks whose relays can support a single antenna due to the limited physical size. In this paper, full DSTC protocol in which there is a data exchange between relays before forwarding signals to destination is proposed to improve the performance of a cooperative relaying system. A lower bound for the average symbol error probability (ASEP) of full DSTC cooperative relaying system in a Rayleigh fading environment is provided. In the case when the Signal to Noise Ratio (SNR) of the relay-relay link is much greater than that of the source-relay link, the upper bound on ASEP of this system is also derived. From the simulations, we show that the average SNR gain of full DSTC system over DSTC system is 3.8dB and the maximum SNR gain is 5dB when the relay-relay distance is small and the relays are in the middle of the source and the destination. The effect of the distance between the relays shows that the performance does not degrade so much as the distance between relays is lower than a half of the source-destination distance. Moreover, we also show that when the error synchronization range is lower than 0.5, the impact of the transmission synchronization error of the relay-destination link on the performance is not considerable

On the performance of distributed space-time coded cooperative relay networks based on inter-relay communications

International audienceA new protocol, called fully distributed space-time coded (FDSTC) protocol having information exchange between relays, is proposed and compared with the conventional distributed space-time coded (DSTC) protocol using non-regenerative relays (NR-relays) and regenerative relays (R-relays). Closed-form error probabilities are derived to verify the simulations. In terms of error performance, the FDSTC protocol gets significant average signal-to-noise ratio (SNR) gains (3.7 dB for NR-relays and 18.1 dB for R-relays). In addition, the impact of the relative distance of relays on the required SNR is reduced up to 70%. The system diversity order using the FDSTC protocol is higher than that using the DSTC protocol (especially, the FDSTC protocol obtains full diversity with NR-relays). As a result, at the same spectral efficiency, FDSTC has better performance in terms of outage probability in high SNR regions. In terms of energy efficiency, the FDSTC protocol is shown to outperform DSTC for long-range transmissions

TỔNG HỢP VÀ ĐẶC TRƯNG hydrogel glucomannan – poly(acrylic acid) NHẠY pH ĐỊNH HƯỚNG ỨNG DỤNG TRONG HỆ THỐNG PHÂN PHỐI 5-aminosalicylic acid CÓ KIỂM SOÁT

In this study, glucomannan-poly(acrylic acid) hydrogels were synthesized under different conditions. The hydrogels consist of glucomannan and acrylic acid and are crosslinked by N,N-methylene-bis-(acrylamide). The structure and morphology of the hydrogels were investigated by using Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The swelling ratio, biodegradation and pH-sensitive properties, relationship between hydrogel swelling rate and 5-ASA adsorption-desorption capacity, influence of medium pH on 5-ASA desorption, and 5-ASA adsorption kinetics were studied. The swelling ratio of the synthesized hydrogel samples is 16.70–56.21 times. This ratio is low in the pH 1.0 media and increases significantly in the pH 7,4 media. The hydrogels are biodegradable in the presence of cellulase (400 U·mg–1) in a pH 7.4 phosphate buffer at 37 °C (69.8% after ten days; the cellulase concentration 1.5 g·L­–1). The hydrogels exhibit high adsorption and desorption capacities for 5-ASA. The adsorption kinetics follows the pseudo-first-order model. These hydrogels can be applied to smart drug delivery systems.Trong nghiên cứu này, hydrogel glucomannan-poly(acrylic acid) đã được tổng hợp ở các điều kiện khác nhau với mục đích ứng dụng vào hệ thống phân phối thuốc 5-amiosalicylic acid (5-ASA) có kiểm soát. Hydrogel được tạo thành từ glucomannan và acrylic acid với tác nhân liên kết N,N-methylene-bis-(acrylamide). Cấu trúc và hình thái của hydrogel được nghiên cứu bằng phổ hồng ngoại chuyển dịch Fourier (FT-IR) và kính hiển vi điện tử quét (SEM). Tỷ lệ trương nở, tính chất phân huỷ sinh học và nhạy pH, mối quan hệ giữa tỷ lệ trương nở của hydrogel và khả năng hấp phụ-giải hấp 5-ASA, ảnh hưởng của pH môi trường để khả năng giải hấp 5-ASA và động học hấp phụ 5-ASA đã được nghiên cứu. Kết quả cho thấy tỷ lệ trương nở của các mẫu hydrogel là 16,70–56,21 lần. Tỷ lệ trương nở của hydrogel thấp ở môi trường pH 1 và tăng lên đáng kể trong môi trường pH 7,4.  Cellulase (400 U·mg–1) trong môi trường đệm pH 7,4 ở 37 °C có khả năng phân hủy sinh học hydrogel (69,8% sau 10 ngày; nồng độ cellulase 1,5 g·L–1). Hydrogel có cả khả năng hấp phụ và giải hấp tốt 5-ASA. Động học quá trình hấp phụ tuân theo mô hình biểu kiến bậc 1. Đây là vật liệu có tiềm năng ứng dụng trong phát triển hệ thống phân phối thuốc thông minh

In vitro antioxidant activity and bioactive compounds from Calocybe indica

Nowadays, the use of mushrooms in medicine is ubiquitous and has achieved particular success. The antioxidants in mushrooms can deactivate free radicals. This study assesses the antioxidant potential of mushroom Calocybe indica with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging methods and the total antioxidant capacity. The mushroom’s ethanol extract exhibits acceptable activity with a low IC50 value (240.11 μg/mL), approximately 2.9 times lower than that of the mushroom Ophiocordyceps sobolifera extract. The ABTS scavenging rate of the extract is around 60% at 500 µg/mL, and the total antioxidant capacity is equivalent to 64.94 ± 1.03 mg of GA/g or 77.42 ± 0.42 μmol of AS/g.  The total phenolics, flavonoids, polysaccharides, and triterpenoids are equivalent to 29.33 ± 0.16 mg of GAE/g, 17.84 ± 0.11 mg of QUE/g (5.04 ± 0.04%), and 4.96 ± 0.04 mg of oleanolic acid/g, respectively. Specifically, the total triterpenoid content has been reported for the first time. The mushroom can have potential biomedical applications