To address the problem that it is difficult to detect an intermediate frequency(IF)signal at the receiving end of a communication system under extremely low signal-to-noise ratio(SNR)conditions,we propose a stochastic...To address the problem that it is difficult to detect an intermediate frequency(IF)signal at the receiving end of a communication system under extremely low signal-to-noise ratio(SNR)conditions,we propose a stochastic resonance(SR)-enhanced sine-signal detection method based on the sign function.By analyzing the SR mechanism of the sine signal and combining it with the characteristics of a dual-sequence frequency-hopping(DSFH)receiver,a periodic stationary solution of the Fokker-Planck equation(FPE)with a time parameter is obtained.The extreme point of the sine signal is selected as the decision time,and the force law of the electromagnetic particles is analyzed.A receiving structure based on the sign function is proposed to maximize the output difference of the system,and the value condition of the sign function is determined.In order to further improve the detection performance,in combination with the central-limit theorem,the sampling points are averaged N times,and the signal-detection problem is transformed into a hypothesis-testing problem under a Gaussian distribution.The theoretical analysis and simulation experiment results confirm that when N is 100 and the SNR is greater than 20 dB,the bit-error ratio(BER)is less than 1.5×10^(-2) under conditions in which the signal conforms to the optimal SR parameters.展开更多
The traditional“bask in daytime and dewed at night”process is essential for fish sauce flavor development;however,the precise role of sunlight in aroma formation remains unclear.In this study,fish sauce mash(FM)was ...The traditional“bask in daytime and dewed at night”process is essential for fish sauce flavor development;however,the precise role of sunlight in aroma formation remains unclear.In this study,fish sauce mash(FM)was prepared using insulation fermentation with koji inoculation.Two batches were subsequently fermented for 30 days under two conditions:a sunlight-treated group(ST)and a darkness-treated group(DT).Electronic nose(Enose)analysis revealed that the ST sample exhibited stronger responses to W1W(sulfur-organic compounds)and W5S(broadrange compounds)than DT and FM.A total of 90 flavor compounds were identified.Sunlight significantly promoted the formation of 8 alcohols,5 aldehydes,7 oxygen heterocyclic compounds,and 4 other classes of compounds.Based on relative odor activity values(ROAV≥1),24 key odorants were identified,among which 3-methylbutanal(ROAV:97.19-336.26),2-ethylfuran(ROAV:35.71-82.64),and 2-methylbutanal(ROAV:32.04-71.70)were the dominant contributors.The metabolic pathways of key odorants were predominantly associated with amino acid catabolism and fatty acid oxidation.Sensory evaluation indicated that sunlight exposure shifted the fish sauce aroma from predominantly meaty(FM)to a more complex and multilayered profile,intensifying roast,fishy,caramel,fermented,sour,ammonia,and rancid notes.Seven key odorants,including 3-methylbutanol,contributed significantly to this transformation.This study elucidates the regulatory role of sunlight in aroma formation during fish sauce fermentation and provides a theoretical basis for improving flavor quality and modernizing traditional fermentation practices.展开更多
Koji fermentation accelerates the formation of volatile/non-volatile metabolites in fish sauce,yet the mechanisms underlying its contribution to flavor development remain unclear.Sixteen compounds,including 3-methylbu...Koji fermentation accelerates the formation of volatile/non-volatile metabolites in fish sauce,yet the mechanisms underlying its contribution to flavor development remain unclear.Sixteen compounds,including 3-methylbuta-nal,2-ethylfuran,2-methylbutanal,and eugenol,were identified as key odorants.These key odorants primarily originated from the metabolism of branched-chain,aromatic,and sulfur-containing amino acids,as well as from the oxidation of unsaturated fatty acids(UFAs).Functional enzymes derived from both bacterial and fungal sources participated in the metabolism of flavor precursors.Significant positive correlations were observed between transaminases-key rate-limiting enzymes in amino acid metabolism-and specific bacterial genera(e.g.,Staphylococcus,Stenotrophomonas,Brucella,Mammaliicoccus,Bacillus,and Enterococcus)as well as the fungal genus Aspergillus.The bacterial genus Ligilactobacillus and fungal genera,including Trichoderma,unclassi-fied_k__Fungi,Periconia,Candida,and Apiotrichum,exhibit significant positive correlations with lipoxygenases.Lipoxygenase catalyzes the conversion of UFAs into unstable lipid hydroperoxides,which then degrade into various flavor compounds.These results elucidate potential metabolic mechanisms of functional microorgan-isms,although their functional validation is necessary.This study provides a theoretical foundation for further verification of microbial functions in fish sauce.It also provides a framework for targeted regulation of the functional microbial community and enzymatic interventions aimed at improving product quality.展开更多
基金Project supported by the Natural Science Foundation of Hebei Province of China(Grant Nos.F2019506031,F2019506037,and F2020506036)the Frontier Innovation Program of Army Engineering University(Grant No.KYSZJQZL2005)the Basic Frontier Science and Technology Innovation Program of Army Engineering University(Grant No.KYSZJQZL2020).
文摘To address the problem that it is difficult to detect an intermediate frequency(IF)signal at the receiving end of a communication system under extremely low signal-to-noise ratio(SNR)conditions,we propose a stochastic resonance(SR)-enhanced sine-signal detection method based on the sign function.By analyzing the SR mechanism of the sine signal and combining it with the characteristics of a dual-sequence frequency-hopping(DSFH)receiver,a periodic stationary solution of the Fokker-Planck equation(FPE)with a time parameter is obtained.The extreme point of the sine signal is selected as the decision time,and the force law of the electromagnetic particles is analyzed.A receiving structure based on the sign function is proposed to maximize the output difference of the system,and the value condition of the sign function is determined.In order to further improve the detection performance,in combination with the central-limit theorem,the sampling points are averaged N times,and the signal-detection problem is transformed into a hypothesis-testing problem under a Gaussian distribution.The theoretical analysis and simulation experiment results confirm that when N is 100 and the SNR is greater than 20 dB,the bit-error ratio(BER)is less than 1.5×10^(-2) under conditions in which the signal conforms to the optimal SR parameters.
基金financially supported by The National Key R&D Program of China(2021YFD2100105)Liaoning Provincial Science and Technology Plan Joint Program Project(2024-MSLH-026).
文摘The traditional“bask in daytime and dewed at night”process is essential for fish sauce flavor development;however,the precise role of sunlight in aroma formation remains unclear.In this study,fish sauce mash(FM)was prepared using insulation fermentation with koji inoculation.Two batches were subsequently fermented for 30 days under two conditions:a sunlight-treated group(ST)and a darkness-treated group(DT).Electronic nose(Enose)analysis revealed that the ST sample exhibited stronger responses to W1W(sulfur-organic compounds)and W5S(broadrange compounds)than DT and FM.A total of 90 flavor compounds were identified.Sunlight significantly promoted the formation of 8 alcohols,5 aldehydes,7 oxygen heterocyclic compounds,and 4 other classes of compounds.Based on relative odor activity values(ROAV≥1),24 key odorants were identified,among which 3-methylbutanal(ROAV:97.19-336.26),2-ethylfuran(ROAV:35.71-82.64),and 2-methylbutanal(ROAV:32.04-71.70)were the dominant contributors.The metabolic pathways of key odorants were predominantly associated with amino acid catabolism and fatty acid oxidation.Sensory evaluation indicated that sunlight exposure shifted the fish sauce aroma from predominantly meaty(FM)to a more complex and multilayered profile,intensifying roast,fishy,caramel,fermented,sour,ammonia,and rancid notes.Seven key odorants,including 3-methylbutanol,contributed significantly to this transformation.This study elucidates the regulatory role of sunlight in aroma formation during fish sauce fermentation and provides a theoretical basis for improving flavor quality and modernizing traditional fermentation practices.
基金supported by The National Key R&D Program of China(2021YFD2100105).
文摘Koji fermentation accelerates the formation of volatile/non-volatile metabolites in fish sauce,yet the mechanisms underlying its contribution to flavor development remain unclear.Sixteen compounds,including 3-methylbuta-nal,2-ethylfuran,2-methylbutanal,and eugenol,were identified as key odorants.These key odorants primarily originated from the metabolism of branched-chain,aromatic,and sulfur-containing amino acids,as well as from the oxidation of unsaturated fatty acids(UFAs).Functional enzymes derived from both bacterial and fungal sources participated in the metabolism of flavor precursors.Significant positive correlations were observed between transaminases-key rate-limiting enzymes in amino acid metabolism-and specific bacterial genera(e.g.,Staphylococcus,Stenotrophomonas,Brucella,Mammaliicoccus,Bacillus,and Enterococcus)as well as the fungal genus Aspergillus.The bacterial genus Ligilactobacillus and fungal genera,including Trichoderma,unclassi-fied_k__Fungi,Periconia,Candida,and Apiotrichum,exhibit significant positive correlations with lipoxygenases.Lipoxygenase catalyzes the conversion of UFAs into unstable lipid hydroperoxides,which then degrade into various flavor compounds.These results elucidate potential metabolic mechanisms of functional microorgan-isms,although their functional validation is necessary.This study provides a theoretical foundation for further verification of microbial functions in fish sauce.It also provides a framework for targeted regulation of the functional microbial community and enzymatic interventions aimed at improving product quality.
