Two sample groups of bulk concentrates consisting mainly of pyrite andchalcopyrite from Daye and Chenghchao Mines in Hubei Province of China were used to investigate theeffect of the action time of lime on its depress...Two sample groups of bulk concentrates consisting mainly of pyrite andchalcopyrite from Daye and Chenghchao Mines in Hubei Province of China were used to investigate theeffect of the action time of lime on its depressive ability for pyrite. The experimental resultsconducted with different samples and collectors showed that the action time between lime and pyritemarkedly influences the depressive ability of lime. The depressive ability of lime increased withthe action time increasing. It was also proved that the depressive results obtained at a large limedosage after a shorter action time are similar to those obtained at a small lime dosage after alonger action time. The increase of depressive ability of lime after a longer action time is becausethat there are different mechanisms in different action time. The composition on the surface ofpyrite acted for different time with lime was studied by using ESCA (Electron Spectroscopic ChemicalAnalysis). The results showed that iron hydroxide and calcium sulphate formed on the pyrite surfaceat the presence of lime in the pulp but the amounts of iron hydroxide and calcium sulphate weredifferent at different action time. At the beginning action time the compound formed on the pyritesurface was mainly calcium sulphate and almost no iron hydroxide formed; but with the action timeincreasing, iron hydroxide formed. The longer the action time, the more iron hydroxide and the lesscalcium sulphate formed. It was considered that the stronger depressive ability of lime after alonger action time is because more iron hydroxide forms on the pyrite surface.展开更多
Due to the excellent dynamic performance,the Finite Control Set Model Predictive Control has been widely used in various types of converters.However,when Finite Control Set Model Predictive Control is adopted,the swit...Due to the excellent dynamic performance,the Finite Control Set Model Predictive Control has been widely used in various types of converters.However,when Finite Control Set Model Predictive Control is adopted,the switching frequency of converters varies significantly with system operating conditions.Consequently,constant-frequency predictive control strategy has been proposed.Two active voltage vectors and a zero voltage vector are selected within each sampling period.The action time sequence is then calculated.Due to the unsymmetrical distribution of current variation rates around zero,the calculated value of the voltage-vector action time will turn up negative.According to common sense,the voltage-vector action time is greater than or equal to zero.The action time is normally forced to zero whenever a negative value is predicted,resulting in the control failure and performance deterioration.To solve this problem,this paper proposes modified strategy.The modified strategy examines the action time calculated out.When negative action time comes out,the modified strategy reselects the active voltage vector accordingly,instead of forcing the action time to be zero.Optimized action time sequence is further determined by minimizing the cost function.The effectiveness of the modified strategy is clearly verified by experimental tests,and analytical remarks are all founded in practical results.展开更多
Background and Objective: Although globally admitted as the most valuable tool to prevent prolongation of labor, the partogram has failed to be commonly used. This is due to its alleged complexity. Based on the simpli...Background and Objective: Although globally admitted as the most valuable tool to prevent prolongation of labor, the partogram has failed to be commonly used. This is due to its alleged complexity. Based on the simplified model proposed by Debdas, the so called paperless partogram, we aimed at evaluating the ability of only using the alert and action lines to prevent prolongation of labor. Methods: This was a cross-sectional study including labor records of women delivered at King Baudouin Hospital of Kinshasa (secondary level) from 01/01 till 31/12/2013. The study was approved by the Faculty Ethical Committee. Inclusion criteria were: 1) live singleton pregnancy, 2) cephalic fetal presentation, 3) lack of uterine scar, 4) monitoring in labor ward by 4 cm of cervical dilation, and 5) delivery at term. For every record, the expected time of delivery (ETD = 6 hours after 4 cm of cervical dilation) was considered “Alert EDT” to which 4 hours were added to obtain the “Action EDT”. Irrespective of other fetal and maternal features contained in the traditional partogram Alert and Action ETD were checked a posteriori on Debdas’s model to derive the appropriate outcome of labor. Results: The study included 357 participants, of which 219 primiparous and 138 multiparous. Vaginal delivery took place in 91% of cases. Full cervical dilation was achieved after 8 - 9 hours (9.5 ± 1.8 hours for primiparous and 8.4 ± 1.7 hours for multiparous women), namely 2 - 3 hours following Alert ETD). This duration is close to the Action ETD. For 32 cesarean sections (9%) final decision took place within the Alert ETD. Conclusion: Using only Alert and Action ETD was found convenient to derive appropriate measures for the outcome of labor. So, the paperless partogram is a simplified method to manage the active stage of labor that could prevent prolongation of labor in our setting.展开更多
针对传统点积注意力缺乏方向性的问题,建立了一种基于余弦相似性的定向注意力模型(directed attention model,DAM)。为有效表示视频帧时空特征间的方向关系,运用余弦相似性理论,定义了注意力机制中关系函数,能够去除特征间关系绝对值;...针对传统点积注意力缺乏方向性的问题,建立了一种基于余弦相似性的定向注意力模型(directed attention model,DAM)。为有效表示视频帧时空特征间的方向关系,运用余弦相似性理论,定义了注意力机制中关系函数,能够去除特征间关系绝对值;为降低注意力机制计算量,从时间和空间两个维度上对运算进行分解;结合线性注意力运算,进一步优化计算复杂度。实验分为两个阶段:对定向注意力各模块开展了4个消融实验,以表现DAM在精确度和效率方面的最佳性能;该模型在Sth-Sth V1(somethingsomething V1)数据集上的精确度较I3D-NL(inflated 3D ConvNet non-local)高7.3%,在UCF101(101 human action classes from videos in the wild)数据集上的识别精确率为95.7%。研究成果在安全监控、自动驾驶等方面应用前景广泛。展开更多
文摘Two sample groups of bulk concentrates consisting mainly of pyrite andchalcopyrite from Daye and Chenghchao Mines in Hubei Province of China were used to investigate theeffect of the action time of lime on its depressive ability for pyrite. The experimental resultsconducted with different samples and collectors showed that the action time between lime and pyritemarkedly influences the depressive ability of lime. The depressive ability of lime increased withthe action time increasing. It was also proved that the depressive results obtained at a large limedosage after a shorter action time are similar to those obtained at a small lime dosage after alonger action time. The increase of depressive ability of lime after a longer action time is becausethat there are different mechanisms in different action time. The composition on the surface ofpyrite acted for different time with lime was studied by using ESCA (Electron Spectroscopic ChemicalAnalysis). The results showed that iron hydroxide and calcium sulphate formed on the pyrite surfaceat the presence of lime in the pulp but the amounts of iron hydroxide and calcium sulphate weredifferent at different action time. At the beginning action time the compound formed on the pyritesurface was mainly calcium sulphate and almost no iron hydroxide formed; but with the action timeincreasing, iron hydroxide formed. The longer the action time, the more iron hydroxide and the lesscalcium sulphate formed. It was considered that the stronger depressive ability of lime after alonger action time is because more iron hydroxide forms on the pyrite surface.
基金supported in part by the National Key Basic Research Program of China ("973" Program) (Grant No. 2013CB035602)the National Natural Science Foundation of China (Grant No. 51107084)the Doctoral Program of Higher Education of China(Grant No. 20100032120081)
文摘Due to the excellent dynamic performance,the Finite Control Set Model Predictive Control has been widely used in various types of converters.However,when Finite Control Set Model Predictive Control is adopted,the switching frequency of converters varies significantly with system operating conditions.Consequently,constant-frequency predictive control strategy has been proposed.Two active voltage vectors and a zero voltage vector are selected within each sampling period.The action time sequence is then calculated.Due to the unsymmetrical distribution of current variation rates around zero,the calculated value of the voltage-vector action time will turn up negative.According to common sense,the voltage-vector action time is greater than or equal to zero.The action time is normally forced to zero whenever a negative value is predicted,resulting in the control failure and performance deterioration.To solve this problem,this paper proposes modified strategy.The modified strategy examines the action time calculated out.When negative action time comes out,the modified strategy reselects the active voltage vector accordingly,instead of forcing the action time to be zero.Optimized action time sequence is further determined by minimizing the cost function.The effectiveness of the modified strategy is clearly verified by experimental tests,and analytical remarks are all founded in practical results.
文摘Background and Objective: Although globally admitted as the most valuable tool to prevent prolongation of labor, the partogram has failed to be commonly used. This is due to its alleged complexity. Based on the simplified model proposed by Debdas, the so called paperless partogram, we aimed at evaluating the ability of only using the alert and action lines to prevent prolongation of labor. Methods: This was a cross-sectional study including labor records of women delivered at King Baudouin Hospital of Kinshasa (secondary level) from 01/01 till 31/12/2013. The study was approved by the Faculty Ethical Committee. Inclusion criteria were: 1) live singleton pregnancy, 2) cephalic fetal presentation, 3) lack of uterine scar, 4) monitoring in labor ward by 4 cm of cervical dilation, and 5) delivery at term. For every record, the expected time of delivery (ETD = 6 hours after 4 cm of cervical dilation) was considered “Alert EDT” to which 4 hours were added to obtain the “Action EDT”. Irrespective of other fetal and maternal features contained in the traditional partogram Alert and Action ETD were checked a posteriori on Debdas’s model to derive the appropriate outcome of labor. Results: The study included 357 participants, of which 219 primiparous and 138 multiparous. Vaginal delivery took place in 91% of cases. Full cervical dilation was achieved after 8 - 9 hours (9.5 ± 1.8 hours for primiparous and 8.4 ± 1.7 hours for multiparous women), namely 2 - 3 hours following Alert ETD). This duration is close to the Action ETD. For 32 cesarean sections (9%) final decision took place within the Alert ETD. Conclusion: Using only Alert and Action ETD was found convenient to derive appropriate measures for the outcome of labor. So, the paperless partogram is a simplified method to manage the active stage of labor that could prevent prolongation of labor in our setting.
文摘针对传统点积注意力缺乏方向性的问题,建立了一种基于余弦相似性的定向注意力模型(directed attention model,DAM)。为有效表示视频帧时空特征间的方向关系,运用余弦相似性理论,定义了注意力机制中关系函数,能够去除特征间关系绝对值;为降低注意力机制计算量,从时间和空间两个维度上对运算进行分解;结合线性注意力运算,进一步优化计算复杂度。实验分为两个阶段:对定向注意力各模块开展了4个消融实验,以表现DAM在精确度和效率方面的最佳性能;该模型在Sth-Sth V1(somethingsomething V1)数据集上的精确度较I3D-NL(inflated 3D ConvNet non-local)高7.3%,在UCF101(101 human action classes from videos in the wild)数据集上的识别精确率为95.7%。研究成果在安全监控、自动驾驶等方面应用前景广泛。
