Adaptive Jamming Suppression in Coherent FFH System Using Weighted Equal Gain Combining Receiver over Fading Channels with Imperfect CSI

Fast frequency hopping (FFH) is commonly used as an antijamming communication method. In this paper, we propose efficient adaptive jamming suppression schemes for binary phase shift keying (BPSK) based coherent FFH system, namely, weighted equal gain combining (W-EGC) with the optimum and suboptimum weighting coefficient. We analyze the bit error ratio (BER) of EGC and W-EGC receivers with partial band noise jamming (PBNJ), frequency selective Rayleigh fading, and channel estimation errors. Particularly, closed-form BER expressions are presented with diversity order two. Our analysis is verified by simulations. It is shown that W-EGC receivers significantly outperform EGC. As compared to the maximum likelihood (ML) receiver in conventional noncoherent frequency shift keying (FSK) based FFH, coherent FFH/BPSK W-EGC receivers also show significant advantages in terms of BER. Moreover, W-EGC receivers greatly reduce the hostile jammers’ jamming efficiency

Adaptive Jamming Suppression in Coherent FFH System Using Weighted Equal Gain Combining Receiver over Fading Channels with Imperfect CSI

Fast frequency hopping (FFH) is commonly used as an antijamming communication method. In this paper, we propose efficient adaptive jamming suppression schemes for binary phase shift keying (BPSK) based coherent FFH system, namely, weighted equal gain combining (W-EGC) with the optimum and suboptimum weighting coefficient. We analyze the bit error ratio (BER) of EGC and W-EGC receivers with partial band noise jamming (PBNJ), frequency selective Rayleigh fading, and channel estimation errors. Particularly, closed-form BER expressions are presented with diversity order two. Our analysis is verified by simulations. It is shown that W-EGC receivers significantly outperform EGC. As compared to the maximum likelihood (ML) receiver in conventional noncoherent frequency shift keying (FSK) based FFH, coherent FFH/BPSK W-EGC receivers also show significant advantages in terms of BER. Moreover, W-EGC receivers greatly reduce the hostile jammers' jamming efficiency

Epidemiological and molecular survey of a foodborne disease outbreak caused by Enterococcus faecalis

Objective To investigate a foodborne disease outbreak in a small restaurant, analyze its causes and risk factors, and propose the measures for prevention and control. Methods Using field epidemiology survey to describe the features and analyze the risk factors of the incident. The strains homology was evaluated by pulsed field gel electrophoresis (PFGE). Results The major clinic manifestations of 5 cases were diarrhea and abdominal pain. Dietary survey showed that suspicious food was pot-stewed chicken leg at dinner on June 13, 2019. The result of field hygienic survey indicated that the risk factor of the incident was the long placement time of the pot-stewed chicken leg at normal temperature status and insufficient re-heating time before dinner. Enterococcus faecalis was isolated from 3 anal swabs of cases, the pot-stewed chicken leg and the cutting board swab which sampled in the kitchen, and the strains were 100% homological. Conclusion The outbreak was caused by eating the pot-stewed chicken leg which was contaminated by abundant Enterococcus faecalis. It was suggested to strengthen the food safety awareness of small restaurant employees and the proper cooking method should be mastered

Facile Synthesis of ZnS/N,S Co-doped Carbon Composite from Zinc Metal Complex for High-Performance Sodium-Ion Batteries

ZnS coated on N,S co-doped carbon (ZnS/NSC) composite has been prepared utilizing zinc pyrithione (C₁₀H₈N₂O₂S₂Zn) as raw material via calcination. Through activation using Na₂CO₃ salt, ZnS nanoparticles encapsulated in NSC (denoted as A-ZnS/NSC) with mixed-crystal structure has also been obtained, which reveals much larger specific surface area and more bridges between ZnS and NSC. Based on the existence of bridges (C–S–Zn and S–O–Zn bonds) and the modification of carbon from N,S co-doping, the A-ZnS/NSC composite as an anode for sodium-ion batteries (SIBs) displays significantly enhanced electrochemical performances with a high reversible specific capacity of 516.6 mA h g^–1 (at 100 mA g^–1), outstanding cycling stability (96.9% capacity retention after 100 cycles at 100 mA g^–1), and high rate behavior (364.9 mA h g^–1 even at 800 mA g^–1)

Edge-Rich Quasi-Mesoporous Nitrogen-Doped Carbon Framework Derived from Palm Tree Bark Hair for Electrochemical Applications

Biomass with abundant resources and low price is regarded as potential sources of functionalized carbon-based energy storage and conversion electrode materials. Rational construction and development of biomass-derived carbon equipped with proper morphology, structure, and composition prove the key to highly efficient utilization of advanced energy storage systems. Herein, we use palm tree bark hair as a biomass source and prepare edge/defect-rich quasi-mesoporous carbon (QMC) by a direct pyrolysis followed by NaOH etching strategy. Then, the edge-rich quasi-mesoporous nitrogen-doped carbon (QMNC) is successfully fabricated through the hydrothermal method by making use of edge/defect-rich QMC and urea as carbon precursor and nitrogen source, respectively. The microstructure and composition of the resultant carbon materials are all detected by a series of techniques. In the meantime, the influence of the etching process on the preparation and electrochemical performance of edge-rich QMNC is systematically explored. The relevant results manifest that the as-prepared edge/defect-rich QMC not only possesses edge-rich plane, much increased specific surface area (SSA), and special quasi-mesopores but also reverses good conductivity and gains sufficient defects for subsequent N doping. After introducing N atoms, the obtained edge-rich QMNC exhibits outstanding capacitive property and oxygen reduction reaction performance, which are mainly attributed to the co-effect of edge-rich plane, large SSA, suitable pore structures, and effective N doping (including high doping amount and optimized N configurations). Clearly, our work not only offers an excellent biomass-derived carbon-based electrode material but also opens a fresh avenue for the development of advanced biomass-derived carbon-based electrode materials