In this paper, the Holt’s exponential smoothing and Auto-Regressive Integrated Moving Average (ARIMA) models were used to forecast inflation rate of Zambia using the monthly consumer price index (CPI) data from May 2...In this paper, the Holt’s exponential smoothing and Auto-Regressive Integrated Moving Average (ARIMA) models were used to forecast inflation rate of Zambia using the monthly consumer price index (CPI) data from May 2010 to May 2014. Results show that the ARIMA ((12), 1, 0) is an adequate model which best fits the CPI time series data and is therefore suitable for forecasting CPI and subsequently the inflation rate. However, the choice of the Holt’s exponential smoothing is as good as an ARIMA model considering the smaller deviations in the mean absolute percentage error and mean square error. Moreover, the Holt’s exponential smoothing model is less complicated since you do not require specialised software to implement it as is the case for ARIMA models. The forecasted inflation rate for April and May, 2015 is 7.0 and 6.6 respectively.展开更多
In this article,we present a theoretical study on the sub-bandgap refractive indexes and optical properties of Sidopedβ-Ga_(2)O_(3) thin films based on newly developed models.The measured sub-bandgap refractive index...In this article,we present a theoretical study on the sub-bandgap refractive indexes and optical properties of Sidopedβ-Ga_(2)O_(3) thin films based on newly developed models.The measured sub-bandgap refractive indexes ofβ-Ga_(2)O_(3) thin film are explained well with the new model,leading to the determination of an explicit analytical dispersion of refractive indexes for photon energy below an effective optical bandgap energy of 4.952 eV for theβ-Ga_(2)O_(3) thin film.Then,the oscillatory structures in long wavelength regions in experimental transmission spectra of Si-dopedβ-Ga_(2)O_(3) thin films with different Si doping concentrations are quantitively interpreted utilizing the determined sub-bandgap refractive index dispersion.Meanwhile,effective optical bandgap values of Si-dopedβ-Ga_(2)O_(3) thin films are further determined and are found to decrease with increasing the Si doping concentration as expectedly.In addition,the sub-bandgap absorption coefficients of Si-dopedβ-Ga_(2)O_(3) thin film are calculated under the frame of the Franz–Keldysh mechanism due to the electric field effect of ionized Si impurities.The theoretical absorption coefficients agree with the available experimental data.These key parameters obtained in the present study may enrich the present understanding of the sub-bandgap refractive indexes and optical properties of impurity-dopedβ-Ga_(2)O_(3) thin films.展开更多
We present the analysis of three independent and most widely used image smoothing techniques on a new fractional based convolution edge detector originally constructed by same authors for image edge analysis. The impl...We present the analysis of three independent and most widely used image smoothing techniques on a new fractional based convolution edge detector originally constructed by same authors for image edge analysis. The implementation was done using only Gaussian function as its smoothing function based on predefined assumptions and therefore did not scale well for some types of edges and noise. The experiments conducted on this mask using known images with realistic geometry suggested the need for image smoothing adaptation to obtain a more optimal performance. In this paper, we use the structural similarity index measure and show that the adaptation technique for choosing smoothing function has significant advantages over a single function implementation. The new adaptive fractional based convolution mask can smoothly find edges of various types in detail quite significantly. The method can now trap both local discontinuities in intensity and its derivatives as well as locating Dirac edges.展开更多
The growth of wind energy penetration level in distribution system raises the concern about its impact on the operation of the power system, especially voltage stability and power loss. Among the major concerns, this ...The growth of wind energy penetration level in distribution system raises the concern about its impact on the operation of the power system, especially voltage stability and power loss. Among the major concerns, this paper studied the impact of connecting wind Turbine (WT) in radial distribution system with different penetration levels and different power factor (lead and lag) on power system voltage stability and power loss reduction. Load flow calculation was carried out using forward-backward sweep method. The analysis proceeds on 9- and 33-bus radial distribution systems. Results show that voltage stability enhancement and power loss reduction should be considered as WT installation objective.展开更多
In many applications a heterogeneous population consists of several subpopulations. When each subpopulation can be adequately modeled by a heteroscedastic single-index model, the whole population is characterized by a...In many applications a heterogeneous population consists of several subpopulations. When each subpopulation can be adequately modeled by a heteroscedastic single-index model, the whole population is characterized by a finite mixture of heteroscedastic single-index models. In this article, we propose an estimation algorithm for fitting this model, and discuss the implementation in detail. Simulation studies are used to demonstrate the performance of the algorithm, and a real example is used to illustrate the application of the model.展开更多
目的探讨骨骼肌质量指数(Skeletal muscle mass index,SMI)、肌少症指数(Sarcope-nia index,SI)与呼吸危重症患者营养状态及预后的关系。方法选取2021年9月至2023年8月南通市第一人民医院收治的呼吸危重患者132例。采用改良危重症营养...目的探讨骨骼肌质量指数(Skeletal muscle mass index,SMI)、肌少症指数(Sarcope-nia index,SI)与呼吸危重症患者营养状态及预后的关系。方法选取2021年9月至2023年8月南通市第一人民医院收治的呼吸危重患者132例。采用改良危重症营养风险评分表(The modi-fied nutrition risk in critically ill,mNUTRIC)评估患者营养状况,根据评分结果分为低风险患者(n=83)、高风险患者(n=49),比较低风险患者与高风险患者的SMI、SI。以离开ICU为时间终点评估预后,分为死亡组(n=37)和存活组(n=95),比较死亡组与存活组患者的一般资料,采用多因素Logistic回归模型分析影响呼吸危重症患者死亡的因素,受试者工作特征(Receiver operator characteristic,ROC)曲线分析SMI、SI预测呼吸危重症患者死亡的风险价值。结果与低风险患者相比,高风险患者的SMI、SI降低(P<0.05)。以离开重症监护室(Intensive care unit,ICU)为评估时间终点,与存活组相比,死亡组年龄、入院24 h内的急性生理评分、年龄评分及慢性健康评分(Acute physiology and chronic health evaluation scoring system,APACHEⅡ)评分及降钙素原(Procalcitonin,PCT)水平较高,白蛋白(Albumin,ALB)、SI和SMI则较低(P<0.05)。多因素Logistic回归模型显示,高APACHEⅡ评分及低SMI、SI值是影响呼吸危重症死亡的独立危险因素。ROC曲线显示,SMI、SI单独预测呼吸危重症患者死亡的曲线下面积(Area under curve,AUC)为0.784(0.720~0.839)、0.726(0.657~0.788),采用SMI、SI联合预测AUC为0.890(0.835~0.938),联合预测效能较单独预测效能更好(P<0.05)。结论SMI、SI与呼吸危重症患者营养状态关系密切,两者联合预测呼吸危重症患者死亡的临床价值高于单独预测。展开更多
文摘In this paper, the Holt’s exponential smoothing and Auto-Regressive Integrated Moving Average (ARIMA) models were used to forecast inflation rate of Zambia using the monthly consumer price index (CPI) data from May 2010 to May 2014. Results show that the ARIMA ((12), 1, 0) is an adequate model which best fits the CPI time series data and is therefore suitable for forecasting CPI and subsequently the inflation rate. However, the choice of the Holt’s exponential smoothing is as good as an ARIMA model considering the smaller deviations in the mean absolute percentage error and mean square error. Moreover, the Holt’s exponential smoothing model is less complicated since you do not require specialised software to implement it as is the case for ARIMA models. The forecasted inflation rate for April and May, 2015 is 7.0 and 6.6 respectively.
基金This study was financially supported by the National Natural Science Foundation of China(No.12074324)the Shenzhen Municipal Science and Technology Innovation Council(No.JCJY20180508163404043).
文摘In this article,we present a theoretical study on the sub-bandgap refractive indexes and optical properties of Sidopedβ-Ga_(2)O_(3) thin films based on newly developed models.The measured sub-bandgap refractive indexes ofβ-Ga_(2)O_(3) thin film are explained well with the new model,leading to the determination of an explicit analytical dispersion of refractive indexes for photon energy below an effective optical bandgap energy of 4.952 eV for theβ-Ga_(2)O_(3) thin film.Then,the oscillatory structures in long wavelength regions in experimental transmission spectra of Si-dopedβ-Ga_(2)O_(3) thin films with different Si doping concentrations are quantitively interpreted utilizing the determined sub-bandgap refractive index dispersion.Meanwhile,effective optical bandgap values of Si-dopedβ-Ga_(2)O_(3) thin films are further determined and are found to decrease with increasing the Si doping concentration as expectedly.In addition,the sub-bandgap absorption coefficients of Si-dopedβ-Ga_(2)O_(3) thin film are calculated under the frame of the Franz–Keldysh mechanism due to the electric field effect of ionized Si impurities.The theoretical absorption coefficients agree with the available experimental data.These key parameters obtained in the present study may enrich the present understanding of the sub-bandgap refractive indexes and optical properties of impurity-dopedβ-Ga_(2)O_(3) thin films.
文摘We present the analysis of three independent and most widely used image smoothing techniques on a new fractional based convolution edge detector originally constructed by same authors for image edge analysis. The implementation was done using only Gaussian function as its smoothing function based on predefined assumptions and therefore did not scale well for some types of edges and noise. The experiments conducted on this mask using known images with realistic geometry suggested the need for image smoothing adaptation to obtain a more optimal performance. In this paper, we use the structural similarity index measure and show that the adaptation technique for choosing smoothing function has significant advantages over a single function implementation. The new adaptive fractional based convolution mask can smoothly find edges of various types in detail quite significantly. The method can now trap both local discontinuities in intensity and its derivatives as well as locating Dirac edges.
文摘The growth of wind energy penetration level in distribution system raises the concern about its impact on the operation of the power system, especially voltage stability and power loss. Among the major concerns, this paper studied the impact of connecting wind Turbine (WT) in radial distribution system with different penetration levels and different power factor (lead and lag) on power system voltage stability and power loss reduction. Load flow calculation was carried out using forward-backward sweep method. The analysis proceeds on 9- and 33-bus radial distribution systems. Results show that voltage stability enhancement and power loss reduction should be considered as WT installation objective.
文摘In many applications a heterogeneous population consists of several subpopulations. When each subpopulation can be adequately modeled by a heteroscedastic single-index model, the whole population is characterized by a finite mixture of heteroscedastic single-index models. In this article, we propose an estimation algorithm for fitting this model, and discuss the implementation in detail. Simulation studies are used to demonstrate the performance of the algorithm, and a real example is used to illustrate the application of the model.
文摘目的探讨骨骼肌质量指数(Skeletal muscle mass index,SMI)、肌少症指数(Sarcope-nia index,SI)与呼吸危重症患者营养状态及预后的关系。方法选取2021年9月至2023年8月南通市第一人民医院收治的呼吸危重患者132例。采用改良危重症营养风险评分表(The modi-fied nutrition risk in critically ill,mNUTRIC)评估患者营养状况,根据评分结果分为低风险患者(n=83)、高风险患者(n=49),比较低风险患者与高风险患者的SMI、SI。以离开ICU为时间终点评估预后,分为死亡组(n=37)和存活组(n=95),比较死亡组与存活组患者的一般资料,采用多因素Logistic回归模型分析影响呼吸危重症患者死亡的因素,受试者工作特征(Receiver operator characteristic,ROC)曲线分析SMI、SI预测呼吸危重症患者死亡的风险价值。结果与低风险患者相比,高风险患者的SMI、SI降低(P<0.05)。以离开重症监护室(Intensive care unit,ICU)为评估时间终点,与存活组相比,死亡组年龄、入院24 h内的急性生理评分、年龄评分及慢性健康评分(Acute physiology and chronic health evaluation scoring system,APACHEⅡ)评分及降钙素原(Procalcitonin,PCT)水平较高,白蛋白(Albumin,ALB)、SI和SMI则较低(P<0.05)。多因素Logistic回归模型显示,高APACHEⅡ评分及低SMI、SI值是影响呼吸危重症死亡的独立危险因素。ROC曲线显示,SMI、SI单独预测呼吸危重症患者死亡的曲线下面积(Area under curve,AUC)为0.784(0.720~0.839)、0.726(0.657~0.788),采用SMI、SI联合预测AUC为0.890(0.835~0.938),联合预测效能较单独预测效能更好(P<0.05)。结论SMI、SI与呼吸危重症患者营养状态关系密切,两者联合预测呼吸危重症患者死亡的临床价值高于单独预测。
