RESUMO
The flying bat can detect the difference in Doppler frequency between its echolocation transmission signal and the echoes in its surroundings, enabling it to distinguish between various scenarios effectively. By examining the bio-sonar biomimetic model of a flying bat that uses echo Doppler information for environmental recognition, it may enhance the scene recognition capability of human ultrasound sonar during movement. The paper establishes a three-dimensional clutter model of the flying state of bat bio-sonar for bats emitting constant frequency signals. It proposes a scene recognition method that combines multi-scale time-frequency feature analysis with a convolutional neural network (CNN). The short-time Fourier transform of different scales extract the Doppler and range dimensions, which are then fused to create a multi-scale feature plane containing both Doppler and range information. Combined with CNN's powerful image classification and recognition capabilities, extract features from multi-scale feature planes of different clutter scenes to achieve environment recognition based on the differences in Doppler and range dimensions of echoes in various directions. Through computer simulations, this study provides a numerical interpretation of the environmental classification and perception capabilities of bats in flight. The algorithm significantly improves scenario classification and recognition performance according to simulation results, with accuracy exceeding 98% in varied clutter scenarios at 30 dB signal noise ratio. Based on computer simulations, an experimental scene was constructed and actual echo signals were collected and analyzed. The experiments demonstrate that utilizing Doppler information enables the classification and recognition of cluttered environments. The effectiveness of the proposed algorithm was also verified. Ultrasonic sonar systems, such as navigation robots and helicopter obstacle avoidance, can apply this biomimetic model and algorithm for environmental recognition during motion.
Assuntos
Quirópteros , Ecolocação , Animais , Biomimética , SomRESUMO
Objective:To systematically assess the efficacy and safety of acupuncture therapy for essential hypertension.Methods:A computerized literature search of the Chinese National Knowledge Infrastructure(CNKI),Chongqing VIP Database(CQVIP),Wanfang Academic Journal Full-text Database(Wanfang),China Biology Medicine Disc(CBM),PubMed,Excerpta Medica Database(EMBASE),and Cochrane Library was conducted to retrieve randomized controlled clinical trials on acupuncture as the main intervention for the treatment of essential hypertension published from the inception of the database to 30 January 2021.The risk-of-bias assessment was carried out for each included study according to the Cochrane Handbook.Data analysis was performed using Review Manager 5.4.1 and Stata 15.0.Results:After the screening,46 randomized controlled trials involving a total of 3 859 subjects were included.Primary outcomes included changes in the diastolic blood pressure after intervention[eight studies showed that the acupuncture plus antihypertensive drug group was better than the antihypertensive drug monotherapy group[mean difference(MD)=1.45,95%confidence interval(CI)(0.48,2.43),P=0.004,fixed effects model;I2=39%]and changes in the systolic blood pressure after intervention{11 studies showed that the acupuncture plus antihypertensive drug group was better than the antihypertensive drug monotherapy group[MD=8.60,95%CI(7.12,10.07),P<0.00001,fixed effects model;I2=26%]}.The secondary outcome was antihypertensive efficacy,12 studies of acupuncture monotherapy group[risk ratio(RR)=1.20,95%CI(1.12,1.28),P<0.00001,fixed effects model;I2=36%]and 15 studies of acupuncture combined with antihypertensive drug group[RR=1.27,95%CI(1.20,1.34),P<0.00001,fixed effects model;I2=6%]showed better results than the antihypertensive drug monotherapy group in antihypertensive efficacy.In terms of the adverse events,four studies showed that the acupuncture monotherapy group had fewer adverse events than the antihypertensive drug monotherapy group[RR=0.10,95%CI(0.04,0.25),P<0.00001,fixed effects model;I2=0%].Conclusion:Acupuncture combined with antihypertensive drugs is superior to antihypertensive drugs alone in reducing blood pressure,and acupuncture therapy is effective and safe for the treatment of essential hypertension with fewer side effects.However,there is still a lack of high-quality multicenter randomized double-blinded controlled trials in this field.Rigorous large-sample clinical trials are needed to validate these findings.
RESUMO
BACKGROUND: Chinese herbal medicine has been used to treat hypertension in China and East Asia since centuries. In this study, we conduct an overview of systematic reviews of Chinese herbal medicine in the treatment of primary hypertension to 1) summarize the conclusions of these reviews, 2) evaluate the methodological quality of these reviews, and 3) rate the confidence in the effect on each outcome. METHODS: We comprehensively searched six databases to retrieve systematic reviews of Chinese herbal medicine for primary hypertension from inception to December 31, 2015. We used AMSTAR to evaluate the methodological quality of included reviews, and we classified the quality of evidence for each outcome in included reviews using the GRADE approach. RESULTS: A total of 12 systematic reviews with 31 outcomes were included, among which 11 systematic reviews focus on the therapeutic effect of Chinese herbal medicine combined with conventional medicine or simple Chinese herbal medicine versus simple conventional medicine. Among the 11 items of AMSTAR, the lowest quality was "providing a priori design" item, none review conformed to this item, the next was "stating the conflict of interest" item, only three reviews conformed to this item. Five reviews scored less than seven in AMSTAR, which means that the overall methodological quality was fairly poor. For GRADE, of the 31 outcomes, the quality of evidence was high in none (0 %), moderate in three (10 %), low in 19 (61 %), and very low in nine (29 %). Of the five downgrading factors, risk of bias (100 %) was the most common downgrading factor in the included reviews, followed by imprecision (42 %), inconsistency (39 %), publication bias (39 %), and indirectness (0 %). CONCLUSIONS: The methodological quality of systematic reviews about Chinese herbal medicine for primary hypertension is fairly poor, and the quality of evidence level is low. Physicians should be cautious when applying the interventions in these reviews for primary hypertension patients in clinical practice.
