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文章根据介质膜滤波器为最小相位滤波器的特点,提出了一种从介质膜滤波器的幅度响应重构出相位响应,然后求出它的群速度延迟以及色散的数值方法.最后,实验验证了理论计算结果.

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Objective: To investigate the predictive value of endotoxin (Endotoxin), procalcitonin (PCT) combined with neutrophil to lymphocyte ratio (NLR) in predicting urinary sepsis in patients after percutaneous nephrolithotomy (PCNL). Methods: 750 patients who underwent PCNL in the Department of Urology Surgery, The Second Affiliated Hospital of Xi’an Medical College and The First Affiliated Hospital of Air Force Military Medical University from May 2020 to May 2023 were selected as study subjects. Patients were divided into urinary sepsis group (n=45) and non sepsis group (n=705) according to the occurrence of urinary sepsis. The levels of serum Endotoxin, PCT, neutrophils and lymphocytes before PCNL were detected, and NLR was calculated. Serum Endotoxin, PCT levels and NLR were compared in two groups. The factors affecting the risk of urinary sepsis in patients after PCNL were analyzed by multivariate Logistic regression model. The clinical efficacy of serum Endotoxin, PCT combine with NLR in predicting urinary sepsis in patients after PCNL were analyzed by drawn receiver operating characteristic (ROC) curve. Results: Compared with non sepsis group, the serum Endotoxin, PCT and NLR in urinary sepsis group were higher (P＜0.05). Multivariate Logistic regression model analysis showed that, elevated serum Endotoxin, elevated PCT, elevated NLR, positive urine white blood cells, preoperative fever and staghorn calculi were independent risk factors for urinary sepsis in patients after PCNL (P＜0.05). The results of ROC curve analysis showed that, the area under the curve (AUC) of serum Endotoxin, PCT combine with NLR in predicting urinary sepsis in patients after PCNL was 0.913, which was higher than that of the above indicators alone. Conclusion: The increase of serum Endotoxin, PCT and NLR before PCNL may be relate to the occurrence of urinary sepsis in patients after PCNL. Elevate serum Endotoxin and PCT levels, elevate NLR, preoperative fever, positive urine white blood cells and staghorn calculi are risk factors for urinary sepsis in patients after PCNL. Serum Endotoxin, PCT combine with NLR detection has a high predictive value for urinary sepsis in patients after PCNL. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Objective To compare the computed tomography (CT) signs of Corona Virus Disease 2019 (COVID-19) and pneumocystis jirovecii pneumonia (PJP),and improve the level of differential diagnosis.Methods The first CT data of 32 COVID-19 patients admitted to Bao Ding No.1 Central Hospital and Bao Ding infectious Diseases Hospital of Hebei Province and 10 PJP patients admitted to Bao Ding No.1 Central Hospital of Hebei Province from December 2019 to March 2020 were collected, and their CT signs were compared.Results The COVID-19 patients were mainly characterized by multiple lung lesions in subpleural area, and their probability of pleural parallel sign and vascular thickening sign were significantly higher than those of the PJP patients, while the probability of pulmonary balloon sign, lunar arch sign and map sign were significantly lower than those of the PJP patients, with statistical significance (P<0.05) .Conclusion COVID-19 and PJP not only share common CT features but also have typical imaging features and chest CT plays an important role in the differential diagnosis of COVID-19 and PJP. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) is the main component of vehicle exhaust in highway tunnels, which is one of the important parameters for the design of ventilation in road tunnels. It is very necessary to predict the CO concentration accurately and quickly to provide a reference for tunnel ventilation system control and mitigating the concentration of CO timely and to ensure the health and safety of the people in the tunnel. At the same time, it is beneficial to the green and energy-saving operation of the tunnel. Based on the field monitoring data of the road tunnel, random forest (RF) model of CO concentration prediction was established with the four influencing factors, i. e., monitor position, traffic, vehicle speed, wind speed. The model was employed to predict the concentration of CO in a 3 300-long road tunnel and the predictive values were compared with the real values. The results show that the CO concentration prediction model based on Random Forest has good prediction accuracy, which can predict the concentration of CO accurately. The RMSE and R 2 of the testing dataset is 0. 497 4 and 0. 943 7, respectively, which is significantly better than those of the linear regression model and support vector machine (SVM) model. The prediction model can be extended to predict the CO concentration of another tunnel. The RMSE and R 2 of the validation dataset is 0. 909 5 and 0. 729 5, respectively. That is, the CO concentration in the tunnel can be predicted under the condition of known monitor position, traffic, vehicle speed, wind speed. The model provides a reference for tunnel ventilation system control or safety warning. The position of monitor point has the greatest influence on the CO concentration in the tunnel, and the CO gas concentration is the highest at the exit of the tunnel. With the increase of wind speed, the concentration of CO gas in the tunnel gradually decreases. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The thermal environment of maneuvering rudder shaft is a local problem to be considered in the design of thermal protection system of hypersonic missile. The flow structure in rudder shaft gap is complex， and under typical flight conditions， the peak of the local thermal environment of the rudder shaft is more serious than that of in large area. Aiming at the problem of thermal environment of hypersonic maneuvering warhead shaft， combined with numerical calculation and wind tunnel test， the variation of thermal environment of rudder shaft with attack angle， rudder deflection angle and Mach number is studied. Then， a four-parameter interpolation fitting method suitable for predicting the peak heat flow of rudder shaft is established. The results show that， for the rudder like letter“ + ”，the thermal environment of horizontal rudder shaft is the most severe； under the condition of small attack angle， the dimensionless heat flow of the rudder shaft increases gradually with the increase of the rudder deflection angle and Mach number， but under the condition of large attack angle， the influence of Mach number and rudder deflection on the dimensionless heat flow of the rudder shaft is small. The four-parameter fitting method established in this paper can be used to rapidly evaluate the peak thermal environment of the rudder shaft along the trajectory. [ABSTRACT FROM AUTHOR]