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
This paper studies the critical time span and the approximate nonlinear action structure of climatic atmosphere and ocean. The critical time span of the climatic atmosphere and ocean, which is related to the spatial r...This paper studies the critical time span and the approximate nonlinear action structure of climatic atmosphere and ocean. The critical time span of the climatic atmosphere and ocean, which is related to the spatial resolution required, the strength of nonlinear action, and the calculation exactness, may represent the relative temporal scale of predictability. As far as the same characteristic spatial scale is concerned, the minimum critical time span of the ocean is about 9 times of that of atmosphere, several days or more. Usually, the stronger the nonlinear action, the shorter the critical time span with smooth changes of external forces. The approximate structure of nonlinear action of climatic atmosphere and ocean is: the nonlinear action decreases usually with increasing latitude, which is related to the role of the Coriolis force in fluid motion (forming geostrophic current); the nonlinear action changes with the anomalous cyclonic or anticyclonic circulation shear, for instance, when the strength of anomalous eastward zonal circulation is comparable to that of anomalous meridional circulation, the nonlinear action is the strongest; wind stress plus gradient forces enhance the nonlinear action, etc.展开更多
Two mathematical models for combined refraction-diffraction of regular and irregular waves on non-uniform current in water of slowly varying topography are presented in this paper. Model I is derived by wave theory an...Two mathematical models for combined refraction-diffraction of regular and irregular waves on non-uniform current in water of slowly varying topography are presented in this paper. Model I is derived by wave theory and variational principle separately. It has two kinds of expressions including the dissipation term. Model n is based on the energy conservation equation with energy flux through the wave crest lines in orthogonal curvilinear coordinates and the wave kinematic conservation equation. The analysis and comparison and special cases of these two models are also given.展开更多
A new numerical finite difference iteration method for refraction-diffraction of waves ia water of slowly varying current and topography is developed in this paper. And corresponding theoretical model including the di...A new numerical finite difference iteration method for refraction-diffraction of waves ia water of slowly varying current and topography is developed in this paper. And corresponding theoretical model including the dissipation term is briefly described, together with some analysis and comparison of computational results of the model with measurements in a hydraulic scale model (Berkhoff et al., 1982). An example of practical use of the method is given, showing that the present model is useful to engineering practice.展开更多
The action (the product of radiated energy and the time of emission) of the radiation fields generated by four types of radiators, namely, short electric dipole, small magnetic dipole, travelling wave antenna and bi-c...The action (the product of radiated energy and the time of emission) of the radiation fields generated by four types of radiators, namely, short electric dipole, small magnetic dipole, travelling wave antenna and bi-conical antenna is investigated with special reference to the charge associated with the current waveform which is responsible for the radiation. The results obtained can be summarized by the order of magnitude inequality where A is the action (product of the radiated energy and the time of emission), h is the Planck constant, q is the charge associated with the current that gave rise to the radiation and e is the electronic charge. The condition is obtained when the length of the antenna and its radius are pushed to its extreme natural limits. Based on the results obtained here and elsewhere, it is suggested that this inequality is valid in general for electromagnetic radiation fields as predicted by classical electrodynamics.展开更多
Segal’s chronometric theory is based on a space-time D, which might be viewed as a Lie group with a causal structure defined by an invariant Lorentzian form on the Lie algebra u(2). Similarly, the space-time F is rea...Segal’s chronometric theory is based on a space-time D, which might be viewed as a Lie group with a causal structure defined by an invariant Lorentzian form on the Lie algebra u(2). Similarly, the space-time F is realized as the Lie group with a causal structure defined by an invariant Lorentzian form on u(1,1). Two Lie groups G, GF are introduced as representations of SU(2,2): they are related via conjugation by a certain matrix Win Gl(4). The linear-fractional action of G on D is well-known to be global, conformal, and it plays a crucial role in the analysis on space-time bundles carried out by Paneitz and Segal in the 1980’s. This analysis was based on the parallelizing group U(2). In the paper, singularities’ general (“geometric”) description of the linear-fractional conformal GF-action on F is given and specific examples are presented. The results call for the analysis of space-time bundles based on U(1,1) as the parallelizing group. Certain key stages of such an analysis are suggested.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.
基金Acknowledgments. This study is supported by the Key National Program for Developing Basic Sciences (G1999043802) and the National Natural Science Fundation of China under Grant No.49876011.
文摘This paper studies the critical time span and the approximate nonlinear action structure of climatic atmosphere and ocean. The critical time span of the climatic atmosphere and ocean, which is related to the spatial resolution required, the strength of nonlinear action, and the calculation exactness, may represent the relative temporal scale of predictability. As far as the same characteristic spatial scale is concerned, the minimum critical time span of the ocean is about 9 times of that of atmosphere, several days or more. Usually, the stronger the nonlinear action, the shorter the critical time span with smooth changes of external forces. The approximate structure of nonlinear action of climatic atmosphere and ocean is: the nonlinear action decreases usually with increasing latitude, which is related to the role of the Coriolis force in fluid motion (forming geostrophic current); the nonlinear action changes with the anomalous cyclonic or anticyclonic circulation shear, for instance, when the strength of anomalous eastward zonal circulation is comparable to that of anomalous meridional circulation, the nonlinear action is the strongest; wind stress plus gradient forces enhance the nonlinear action, etc.
基金This work was financially supported by the Science Foundation of National Education Committee of China
文摘Two mathematical models for combined refraction-diffraction of regular and irregular waves on non-uniform current in water of slowly varying topography are presented in this paper. Model I is derived by wave theory and variational principle separately. It has two kinds of expressions including the dissipation term. Model n is based on the energy conservation equation with energy flux through the wave crest lines in orthogonal curvilinear coordinates and the wave kinematic conservation equation. The analysis and comparison and special cases of these two models are also given.
基金Science Foundation of National Education Committee of China
文摘A new numerical finite difference iteration method for refraction-diffraction of waves ia water of slowly varying current and topography is developed in this paper. And corresponding theoretical model including the dissipation term is briefly described, together with some analysis and comparison of computational results of the model with measurements in a hydraulic scale model (Berkhoff et al., 1982). An example of practical use of the method is given, showing that the present model is useful to engineering practice.
文摘The action (the product of radiated energy and the time of emission) of the radiation fields generated by four types of radiators, namely, short electric dipole, small magnetic dipole, travelling wave antenna and bi-conical antenna is investigated with special reference to the charge associated with the current waveform which is responsible for the radiation. The results obtained can be summarized by the order of magnitude inequality where A is the action (product of the radiated energy and the time of emission), h is the Planck constant, q is the charge associated with the current that gave rise to the radiation and e is the electronic charge. The condition is obtained when the length of the antenna and its radius are pushed to its extreme natural limits. Based on the results obtained here and elsewhere, it is suggested that this inequality is valid in general for electromagnetic radiation fields as predicted by classical electrodynamics.
文摘Segal’s chronometric theory is based on a space-time D, which might be viewed as a Lie group with a causal structure defined by an invariant Lorentzian form on the Lie algebra u(2). Similarly, the space-time F is realized as the Lie group with a causal structure defined by an invariant Lorentzian form on u(1,1). Two Lie groups G, GF are introduced as representations of SU(2,2): they are related via conjugation by a certain matrix Win Gl(4). The linear-fractional action of G on D is well-known to be global, conformal, and it plays a crucial role in the analysis on space-time bundles carried out by Paneitz and Segal in the 1980’s. This analysis was based on the parallelizing group U(2). In the paper, singularities’ general (“geometric”) description of the linear-fractional conformal GF-action on F is given and specific examples are presented. The results call for the analysis of space-time bundles based on U(1,1) as the parallelizing group. Certain key stages of such an analysis are suggested.
