Analysis of parameter estimation using the sampling-type algorithm of discrete fractional Fourier transform

Parameter estimation is analyzed using two kinds of common sampling-type DFRFT(discrete fractional Fourier transform) algorithm. A model of parameter estimation is established. The factors which influence estimation accuracy are analyzed. And the simulation is made to verify the conclusions. From the theoretic analysis and simulation verification, it can be drawn that, for the estimation of chirp-rate and initial frequency, Pei's method [10] is more suitable if the absolute value of chirp-rate is small relatively; Ozaktas' method [9] is more suitable if the absolute value of chirp-rate is large relatively; and the two methods are both workable if the absolute value of chirp-rate is moderate. The scope of moderate chirp-rate can be approximately determined as [40 Hz/s, 110 Hz/s].

Preface

An artificial neural network(ANN) constitutive model is developed for high strength armor steel tempered at 500 C, 600 C and 650 C based on high strain rate data generated from split Hopkinson pressure bar(SHPB) experiments. A new neural network configuration consisting of both training and validation is effectively employed to predict flow stress. Tempering temperature, strain rate and strain are considered as inputs, whereas flow stress is taken as output of the neural network. A comparative study on Johnsone Cook(Je C) model and neural network model is performed. It was observed that the developed neural network model could predict flow stress under various strain rates and tempering temperatures. The experimental stressestrain data obtained from high strain rate compression tests using SHPB, over a range of tempering temperatures(500e650 C), strains(0.05e0.2) and strain rates(1000e5500/s) are employed to formulate Je C model to predict the high strain rate deformation behavior of high strength armor steels. The J-C model and the back-propagation ANN model were developed to predict the high strain rate deformation behavior of high strength armor steel and their predictability is evaluated in terms of correlation coefficient(R) and average absolute relative error(AARE). R and AARE for the Je C model are found to be 0.7461 and 27.624%, respectively, while R and AARE for the ANN model are 0.9995 and 2.58%, respectively. It was observed that the predictions by ANN model are in consistence with the experimental data for all tempering temperatures.

Intensive follow-up vs conventional follow-up for patients with nonmetastatic colorectal cancer treated with curative intent:A metaanalysis

BACKGROUND The frequency and content of follow-up strategies remain controversial for colorectal cancer(CRC),and scheduled follow-ups have limited value.AIM To compare intensive and conventional follow-up strategies for the prognosis of non-metastatic CRC treated with curative intent using a meta-analysis.METHODS PubMed,Embase,and the Cochrane Library databases were systematically searched for potentially eligible randomized controlled trials(RCTs)from inception until April 2023.The Cochrane risk of bias was used to assess the methodological quality of the included studies.The hazard ratio,relative risk,and 95%confidence interval were used to calculate survival and categorical data,and pooled analyses were performed using the random-effects model.Additional exploratory analyses were performed for sensitivity,subgroups,and publication bias.RESULTS Eighteen RCTs involving 8533 patients with CRC were selected for the final analysis.Intensive follow-up may be superior to conventional follow-up in improving overall survival,but this difference was not statistically significant.Moreover,intensive follow-up was associated with an increased incidence of salvage surgery compared to conventional follow-up.In addition,there was no significant difference in the risk of recurrence between intensive and conventional follow-up strategies,whereas intensive follow-up was associated with a reduced risk of interval recurrence compared to conventional follow-up.Finally,the effects of intensive and conventional follow-up strategies differed when stratified by tumor location and follow-up duration.CONCLUSION Intensive follow-up may have a beneficial effect on the overall survival of patients with non-metastatic CRC treated with curative intent.