The adaptive filter is an effective method to dealing with such kind of non-steady random signal of the heart rate. The algorithm of clipped- error LMS algorithm with variable step size of segmenting type was proposed. We adopted auto-regression predict filter estimating the noise of heart rate signals through Doppler ultrasound sensor. We used it as the reference signal of the adaptive noise cancelling system, its result is to remove some noise of main input, it made SNR raise by about 36 dB, it realized the abstraction of the heart rate signals.
Algorithms ; Echocardiography, Doppler ; Heart Rate ; physiology ; Humans ; Least-Squares Analysis ; Signal Processing, Computer-Assisted

【Objective】 To investigate the changing trends in etiology and treatment of male urethral stricture in recent 10 years. 【Methods】 A total of 940 male patients with urethral stricture admitted to the Department of Urology of Beijing Jishuitan Hospital during Jan.2013 and Dec.2022 were continually collected.The clinical data were divided into two groups according to the time of admission, namely the group from 2013 to 2017 and the group from 2018 to 2022, for a comparative analysis of the previous and subsequent 5 years.The etiology, location, length and the type of treatment of urethral stricture were retrospectively analyzed. 【Results】 The causes of the 940 cases of male urethral stricture were trauma in 447(47.55%), iatrogenic injury in 220(23.40%), idiopathic causes in 128(13.62%), lichen sclerosus (LS) in 78(8.30%), infection in 46(4.89%), and other causes in 21(2.23%).The treatment methods were urethroplasty in 691(73.51%), direct vision internal urethrotomy (DVIU) in 122(12.98%), urethral dilatation in 86(9.15%), and suprapubic cystostomy in 41(4.36%).Compared with the previous 5 years, in the past 5 years, the proportion of urethral stricture caused by trauma decreased significantly (60.34% vs. 41.71%, P<0.001), while the proportion of iatrogenic injury increased significantly (17.63% vs. 26.05%, P=0.005). In the past 5 years, the proportion of urethroplasty increased from 68.81% to 75.66% (P=0.027), while the proportion of DVIU decreased from 19.66% to 9.92% (P<0.001). In the past 5 years, the proportion of membranous urethral stenosis decreased significantly (26.98% vs. 50.85%, χ²=51.06, P<0.001),the proportion of penile urethral stricture (21.40% vs. 7.80%, χ²=26.37, P<0.001) and meatal stenosis (9.30% vs. 4.75%, χ²=5.80, P<0.001) increased significantly. 【Conclusion】 In the past decade, trauma was the main cause of male urethral strictures, but its proportion showed a decreasing trend.Iatrogenic injury led to a gradual increase in urethral strictures, which was the second leading cause of male urethral stricture.The application of urethroplasty increased significantly, making it the main treatment method for male urethral stricture.