The positive ecological interaction between gap formation and natural regeneration has been examined but little research has been carried out on the effects of gaps on natural regeneration in forests under different i...The positive ecological interaction between gap formation and natural regeneration has been examined but little research has been carried out on the effects of gaps on natural regeneration in forests under different intensities of disturbance.This study evaluates the composition,diversity,regeneration density and abundance of natural regeneration of tree species in gaps in undisturbed,intermittently disturbed,and disturbed forest sites.Bia Tano Forest Reserve in Ghana was the study area and three gaps each were selected in the three forest site categories.Ten circular subsampling areas of 1 m2 were delineated at 2 m spacing along north,south,east,and west transects within individual gaps.Data on natural regeneration<350 cm height were gathered.The results show that the intensity of disturbance was disproportional to gap size.Species diversity differed significantly between undisturbed and disturbed sites and,also between intermittently disturbed and disturbed sites for Simpson’s(1-D),Equitability(J),and Berger-Parker(B-P)indices.However,there was no significant difference among forest sites for Shannon diversity(H)and Margalef richness(MI)indices.Tree species composition on the sites differed.Regeneration density on the disturbed site was significantly higher than on the two other sites.Greater abundance and density of shade-dependent species on all sites identified them as opportunistic replacements of gap-dependent pioneers.Pioneer species giving way to shade tolerant species is a natural process,thus make them worst variant in gap regeneration.展开更多
A lab-scale intermittently aerated sequencing batch reactor（IASBR）was applied to treat anaerobically digested swine wastewater（ADSW）to explore the removal characteristics of veterinary antibiotics.The removal rate...A lab-scale intermittently aerated sequencing batch reactor（IASBR）was applied to treat anaerobically digested swine wastewater（ADSW）to explore the removal characteristics of veterinary antibiotics.The removal rates of 11 veterinary antibiotics in the reactor were investigated under different chemical organic demand（COD）volumetric loadings,solid retention times（SRT）and ratios of COD to total nitrogen（TN）or COD/TN.Both sludge sorption and biodegradation were found to be the major contributors to the removal of veterinary antibiotics.Mass balance analysis revealed that greater than 60%of antibiotics in the influent were biodegraded in the IASBR,whereas averagely 24%were adsorbed by sludge under the condition that sludge sorption gradually reached its equilibrium.Results showed that the removal of antibiotics was greatly influenced by chemical oxygen demand（COD）volumetric loadings,which could achieve up to 85.1%±1.4%at 0.17±0.041 kg COD/m-3/day,while dropped to 75.9%±1.3%and 49.3%±12.1%when COD volumetric loading increased to 0.65±0.032 and1.07±0.073 kg COD/m-3/day,respectively.Tetracyclines,the dominant antibiotics in ADSW,were removed by 87.9%in total at the lowest COD loading,of which 30.4%were contributed by sludge sorption and 57.5%by biodegradation,respectively.In contrast,sulfonamides were removed about 96.2%,almost by biodegradation.Long SRT seemed to have little obvious impact on antibiotics removal,while a shorter SRT of 30–40 day could reduce the accumulated amount of antibiotics and the balanced antibiotics sorption capacity of sludge.Influent COD/TN ratio was found not a key impact factor for veterinary antibiotics removal in this work.展开更多
Ventilation is an important engineering measure to control the airborne infection risk of acute respiratory diseases,e.g.,Corona Virus Disease 2019(COVID-19).Occupancy-aided ventilation methods can effectively improve...Ventilation is an important engineering measure to control the airborne infection risk of acute respiratory diseases,e.g.,Corona Virus Disease 2019(COVID-19).Occupancy-aided ventilation methods can effectively improve the airborne infection risk control performance with a sacrifice of decreasing working productivity because of the reduced occupancy.This study evaluates the effectiveness of two occupancy-aided ventilation methods,i.e.,the continuously reduced occupancy method and the intermittently reduced occupancy method.The continuously reduced occupancy method is determined by the steady equation of the mass conservation law of the indoor contaminant,and the intermittently reduced occupancy method is determined by a genetic algorithm-based optimization.A two-scenarios-based evaluation framework is developed,i.e.,one with targeted airborne infection risk control performance(indicated by the mean rebreathed fraction)and the other with targeted working productivity(indicated by the accumulated occupancy).The results show that the improvement in the airborne infection risk control performance linearly and quadratically increases with the reduction in the working productivity for the continuously reduced occupancy method and the intermittently reduced occupancy method respectively.At a given targeted airborne infection risk control performance,the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the working productivity by up to 92%.At a given targeted working productivity,the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the airborne infection risk control performance by up to 38%.展开更多
An intermittently aerated sequencing batch reactor （IASBR） and a traditional sequencing batch reactor （SBR） were parallelly constructed to treat digested piggery wastewater, which was in high NH4＋ -N concentratio...An intermittently aerated sequencing batch reactor （IASBR） and a traditional sequencing batch reactor （SBR） were parallelly constructed to treat digested piggery wastewater, which was in high NH4＋ -N concentration but in a low COD/TN ratio. Their pollutant removal perfonnance was compared under COD/TN ratios of 1.6-3.4 d and hydraulic retention times of 5 3 d. The results showed that the IASBR removed TN, NH4＋-N and TOC more efficiently than the SBR. The average removal rates of TN, NH4＋-N and TOC were 83.1%, 96.5%, and 89.0%, respectively, in the IASBR, significantly higher than the corresponding values of 74.8%, 82.0%, and 86.2%. in the SBR. Mass balance of organic carbon revealed that the higher TN removal in the IASBR might be attributed to its efficient utilization of the organic carbon for denitrification, since that 48.7%- 52.2% of COD was used for denitrification in the IASBR, higher than the corresponding proportion of 43.1%-47.4% in the SBR. A prc-anoxic process in the IASBR would enhance the ammonium oxidation while restrict the nitrite oxidation. Anoxic duration of 40-80 min should be beneficial for achieving stable nitritation.展开更多
Removal of chromium （VI） dissolved in water by intermittent foam separation was implemented with cetyl trimethyo ammonium bromide as surfactant. The influence of various factors on removal efficiency was systematica...Removal of chromium （VI） dissolved in water by intermittent foam separation was implemented with cetyl trimethyo ammonium bromide as surfactant. The influence of various factors on removal efficiency was systematically studied. The removal efficiency has a maximum value near pH 4.0; thus, most experiments were carried out at pH 4.0. The orthogonal experiment was conducted to confirm the optimal operating parameters. The orthogonal experimental results show that when the liquid feed concentration is l0 mg/L, the pH value of feed solution is 4.00, air flow rates 0.9 L/min, surfactant dosage is 300 mg/L, the maximum removal efficiency of chromium （VI） reaches 97.80%, and condense multiple reaches 1 711. The kinetic test indicates that the foam separation of chromium is a first-order process. The equivalent rate constant calculated from the slope is 0.406 4, and the equivalent rate equation is obtained.展开更多
针对弱扰动下Bonhoeffer-Van Der Pol振子表现出复杂类型的振荡,采用Poincare mapping和回归映射等非线性动力学的分析方法对其进行了研究,考察了弱扰动周期与强度对混合模式振荡类型的影响.结果表明:虽然研究的动力系统是简单的,但是...针对弱扰动下Bonhoeffer-Van Der Pol振子表现出复杂类型的振荡,采用Poincare mapping和回归映射等非线性动力学的分析方法对其进行了研究,考察了弱扰动周期与强度对混合模式振荡类型的影响.结果表明:虽然研究的动力系统是简单的,但是表现出的动力学行为是比较复杂的;所观察到的现象与相似的模型有着相关性.展开更多
基金the Internal Grant Agency of Mendel University in Brno(MENDELU,project no.LDF_VP_2019015)。
文摘The positive ecological interaction between gap formation and natural regeneration has been examined but little research has been carried out on the effects of gaps on natural regeneration in forests under different intensities of disturbance.This study evaluates the composition,diversity,regeneration density and abundance of natural regeneration of tree species in gaps in undisturbed,intermittently disturbed,and disturbed forest sites.Bia Tano Forest Reserve in Ghana was the study area and three gaps each were selected in the three forest site categories.Ten circular subsampling areas of 1 m2 were delineated at 2 m spacing along north,south,east,and west transects within individual gaps.Data on natural regeneration<350 cm height were gathered.The results show that the intensity of disturbance was disproportional to gap size.Species diversity differed significantly between undisturbed and disturbed sites and,also between intermittently disturbed and disturbed sites for Simpson’s(1-D),Equitability(J),and Berger-Parker(B-P)indices.However,there was no significant difference among forest sites for Shannon diversity(H)and Margalef richness(MI)indices.Tree species composition on the sites differed.Regeneration density on the disturbed site was significantly higher than on the two other sites.Greater abundance and density of shade-dependent species on all sites identified them as opportunistic replacements of gap-dependent pioneers.Pioneer species giving way to shade tolerant species is a natural process,thus make them worst variant in gap regeneration.
文摘A lab-scale intermittently aerated sequencing batch reactor（IASBR）was applied to treat anaerobically digested swine wastewater（ADSW）to explore the removal characteristics of veterinary antibiotics.The removal rates of 11 veterinary antibiotics in the reactor were investigated under different chemical organic demand（COD）volumetric loadings,solid retention times（SRT）and ratios of COD to total nitrogen（TN）or COD/TN.Both sludge sorption and biodegradation were found to be the major contributors to the removal of veterinary antibiotics.Mass balance analysis revealed that greater than 60%of antibiotics in the influent were biodegraded in the IASBR,whereas averagely 24%were adsorbed by sludge under the condition that sludge sorption gradually reached its equilibrium.Results showed that the removal of antibiotics was greatly influenced by chemical oxygen demand（COD）volumetric loadings,which could achieve up to 85.1%±1.4%at 0.17±0.041 kg COD/m-3/day,while dropped to 75.9%±1.3%and 49.3%±12.1%when COD volumetric loading increased to 0.65±0.032 and1.07±0.073 kg COD/m-3/day,respectively.Tetracyclines,the dominant antibiotics in ADSW,were removed by 87.9%in total at the lowest COD loading,of which 30.4%were contributed by sludge sorption and 57.5%by biodegradation,respectively.In contrast,sulfonamides were removed about 96.2%,almost by biodegradation.Long SRT seemed to have little obvious impact on antibiotics removal,while a shorter SRT of 30–40 day could reduce the accumulated amount of antibiotics and the balanced antibiotics sorption capacity of sludge.Influent COD/TN ratio was found not a key impact factor for veterinary antibiotics removal in this work.
基金supported by the Fundamental Research Funds for the Central Universities(No.xzy012022078)the Top Young Talent Programme of Xi’an Jiaotong University(No.011900/71211201030703).
文摘Ventilation is an important engineering measure to control the airborne infection risk of acute respiratory diseases,e.g.,Corona Virus Disease 2019(COVID-19).Occupancy-aided ventilation methods can effectively improve the airborne infection risk control performance with a sacrifice of decreasing working productivity because of the reduced occupancy.This study evaluates the effectiveness of two occupancy-aided ventilation methods,i.e.,the continuously reduced occupancy method and the intermittently reduced occupancy method.The continuously reduced occupancy method is determined by the steady equation of the mass conservation law of the indoor contaminant,and the intermittently reduced occupancy method is determined by a genetic algorithm-based optimization.A two-scenarios-based evaluation framework is developed,i.e.,one with targeted airborne infection risk control performance(indicated by the mean rebreathed fraction)and the other with targeted working productivity(indicated by the accumulated occupancy).The results show that the improvement in the airborne infection risk control performance linearly and quadratically increases with the reduction in the working productivity for the continuously reduced occupancy method and the intermittently reduced occupancy method respectively.At a given targeted airborne infection risk control performance,the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the working productivity by up to 92%.At a given targeted working productivity,the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the airborne infection risk control performance by up to 38%.
文摘An intermittently aerated sequencing batch reactor （IASBR） and a traditional sequencing batch reactor （SBR） were parallelly constructed to treat digested piggery wastewater, which was in high NH4＋ -N concentration but in a low COD/TN ratio. Their pollutant removal perfonnance was compared under COD/TN ratios of 1.6-3.4 d and hydraulic retention times of 5 3 d. The results showed that the IASBR removed TN, NH4＋-N and TOC more efficiently than the SBR. The average removal rates of TN, NH4＋-N and TOC were 83.1%, 96.5%, and 89.0%, respectively, in the IASBR, significantly higher than the corresponding values of 74.8%, 82.0%, and 86.2%. in the SBR. Mass balance of organic carbon revealed that the higher TN removal in the IASBR might be attributed to its efficient utilization of the organic carbon for denitrification, since that 48.7%- 52.2% of COD was used for denitrification in the IASBR, higher than the corresponding proportion of 43.1%-47.4% in the SBR. A prc-anoxic process in the IASBR would enhance the ammonium oxidation while restrict the nitrite oxidation. Anoxic duration of 40-80 min should be beneficial for achieving stable nitritation.
文摘Removal of chromium （VI） dissolved in water by intermittent foam separation was implemented with cetyl trimethyo ammonium bromide as surfactant. The influence of various factors on removal efficiency was systematically studied. The removal efficiency has a maximum value near pH 4.0; thus, most experiments were carried out at pH 4.0. The orthogonal experiment was conducted to confirm the optimal operating parameters. The orthogonal experimental results show that when the liquid feed concentration is l0 mg/L, the pH value of feed solution is 4.00, air flow rates 0.9 L/min, surfactant dosage is 300 mg/L, the maximum removal efficiency of chromium （VI） reaches 97.80%, and condense multiple reaches 1 711. The kinetic test indicates that the foam separation of chromium is a first-order process. The equivalent rate constant calculated from the slope is 0.406 4, and the equivalent rate equation is obtained.
文摘针对弱扰动下Bonhoeffer-Van Der Pol振子表现出复杂类型的振荡,采用Poincare mapping和回归映射等非线性动力学的分析方法对其进行了研究,考察了弱扰动周期与强度对混合模式振荡类型的影响.结果表明:虽然研究的动力系统是简单的,但是表现出的动力学行为是比较复杂的;所观察到的现象与相似的模型有着相关性.
