ABSTRACT
Objective:To study the value of autoregressive integrated moving average (ARIMA) and autoregressive (AR) models in predicting the daily number of ambulances in prehospital emergency medical services demand in Guangzhou.Methods:Matlab simulation software was used to analyze the emergency dispatching departure records in Guangzhou from January 1, 2021 to December 31, 2021. A time series for the number of ambulances per day was calculated. After identifying the time series prediction model, ARIMA(1,1,1), AR(4) and AR(7) models were obtained. These models were used to predict the number of ambulances per day. ARIMA(1,1,1) model divided the time series into the training set and test set. Prony method was used for parameter calculation, and the demands of number of ambulances of the next few months were forecasted. AR(4) and AR(7) models used uniformity coefficient to forecast the demands of number of ambulances on that very day.Results:ARIMA(1,1,1), AR(4) and AR(7) can effectively predict the number of ambulances per day. The prediction fitting error of ARIMA (1,1,1) decreased with the extension of prediction time. The mean absolute percentage error (MAPE) of forecast results of daily vehicle output of emergency dispatching within two months was less than 6% and the predicted results were almost within the 95% confidence interval. The residual analysis of the model verified that the model was significantly effective.Conclusions:ARIMA model can make a long-term within two months and effective prediction fitting of the daily vehicle output of emergency dispatching, and AR model can make a short-term and effective prediction of the daily vehicle output of emergency dispatching.
ABSTRACT
Objective To explore the application of a three-dimensional simulation system in extended liver resections.Methods A three-dimensional surgical simulation system was used for preoperative assessment and for computer simulation to estimate the resected liver volume,the residual liver volume,and the surgical resection margins.The software virtual liver resection was used to choose the most optimal surgical option.The actual resection,the postoperative liver volume and the actual surgical resection margins were compared.Results 1 patient was diagnosed by ultrasound to develop ascites on post-operative day 2.Another patient was diagnosed by transthoracic ultrasound to have moderate pleural effusion on postoperative day 1.Postoperative liver failure developed in 1 patient.There was no patient who developed bile leakage.The average length of stay was 6 ～ 85 days (average 22 d).There was no recurrence within 1 month after surgery and there was no postoperative deaths.Condusions The three-dimensional surgery simulation system was effective.It gave an accurate evaluation and simulation of the liver surgery.In extended liver resection,it gave good guidance and help.