The outbreak of COVID-19 in December 2019 has exerted a wide and everlasting impact on the world,which has also influenced education enormously.The adjustment of objective learning environment during the COVID-19 pand...The outbreak of COVID-19 in December 2019 has exerted a wide and everlasting impact on the world,which has also influenced education enormously.The adjustment of objective learning environment during the COVID-19 pandemic makes the influence of non-intellectual factors on college students worthy of investigation,research and analysis.Based on this,we have launched a questionnaire survey on 500 college students who have witnessed the pandemic,and referred to related literature,network documents,news reports,contrast and analysis of college students’non-intelligence factors before and after the outbreak of the different levels of change,summing up some new measures to promote the development of college students’non-intelligence factors under the COVID-19 outbreak for online learning and autonomous learning.展开更多
This work presents a novel approach to the dynamic response analysis of a Euler-Bernoulli beam resting on a Winkler soil model and subjected to an impact loading.The approach considers that damping has much less impor...This work presents a novel approach to the dynamic response analysis of a Euler-Bernoulli beam resting on a Winkler soil model and subjected to an impact loading.The approach considers that damping has much less importance in controlling the maximum response to impulsive loadings because the maximum response is reached in a very short time,before the damping forces can dissipate a significant portion of the energy input into the system.The development of two sine series solutions,relating to different types of impulsive loadings,one involving a single concentrated force and the other a distributed line load,are presented.This study revealed that when a simply supported Euler-Bernoulli beam,resting on a Winkler soil model,is subject to an impact load,the resulting vertical displacements,bending moments and shear forces produced along the span of the beam are considerably affected.In particular,the quantification of this effect is best observed,relative to the corresponding static solution,via an amplification factor.The computed impact amplification factors,for the sub-grade moduli used in this study,were in magnitude greater than 2,thus confirming the multiple-degree-of-freedom nature of the problem.展开更多
A novel approach for analyzing coupled vibrations between vehicles and bridges is presented,taking into account spatiotemporal effects and mechanical phenomena resulting fromvehicle braking.Efficient modeling and solu...A novel approach for analyzing coupled vibrations between vehicles and bridges is presented,taking into account spatiotemporal effects and mechanical phenomena resulting fromvehicle braking.Efficient modeling and solution of bridge vibrations induced by vehicle deceleration are realized using this method.The method’s validity and reliability are substantiated through numerical examples.A simply supported beam bridge with a corrugated steel web is taken as an example and the effects of parameters such as the initial vehicle speed,braking acceleration,braking location,and road surface roughness on the mid-span displacement and impact factor of the bridge are analyzed.The results show that vehicle braking significantly amplifies mid-span displacement and impact factor responses in comparison to uniform vehicular motion across the bridge.Notably,the influence of wheelto-bridge friction forces is of particular significance and cannot be overlooked.When the vehicle initiates braking near the middle of the span,both the mid-span displacement and impact factor of the bridge exhibit substantial increases,further escalating with higher braking acceleration.Under favorable road surface conditions,the midspan displacement and the impact factor during vehicle braking may exceed the design values stipulated by codes.It is important to note that road surface roughness exerts a more pronounced effect on the impact factor of the bridge in comparison to the effects of vehicle braking.展开更多
Herbaceous plants are widely distributed on islands and where they exhibit spatial heterogeneity.Accurately identifying the impact factors that drive spatial heterogeneity can reveal typical island biodiversity patter...Herbaceous plants are widely distributed on islands and where they exhibit spatial heterogeneity.Accurately identifying the impact factors that drive spatial heterogeneity can reveal typical island biodiversity patterns.Five southern islands in the Miaodao Archipelago,North China were studied herein.The spatial distribution of herbaceous plant diversity on these islands was analyzed,and the impact factors and their degree of impact on spatial heterogeneity were identified using CCA ordination and ANOVA.The results reveal 114 herbaceous plant species,belonging to 94 genera from 34 families in the50 plots sampled.The total species numbers on different islands were significantly positively correlated with island area,and the average a diversity was correlated with human activities,while the(3 diversity among islands was more affected by island area than mutual distances.Spatial heterogeneity within islands indicated that the diversities were generally high in areas with higher altitude,slope,total nitrogen,total carbon,and canopy density,and lower moisture content,pH,total phosphorus,total potassium,and aspect.Among the environmental factors,pH,canopy density,total K,total P,moisture content,altitude,and slope had significant gross effects,but only canopy density exhibited a significant net effect.Terrain affected diversity by restricting plantation,plantation in turn influenced soil properties and the two together affected diversity.Therefore,plantation was ultimately the fundamental driving factor for spatial heterogeneity in herbaceous plant diversity on the five islands.展开更多
This article developed a decomposition model of energy productivity on the basis of the economic growth model. Four factors were considered which may influence China’s energy productivity according to this model: tec...This article developed a decomposition model of energy productivity on the basis of the economic growth model. Four factors were considered which may influence China’s energy productivity according to this model: technology improvement, resource allocation structure, industrial structure and institute arrangement. Then, an econometric model was employed to test the four factors empirically on the basis of China’s statistical data from 1978 to 2004. Results indicated that capital deepening con- tributes the most (207%) to energy efficiency improvement, and impact from labor forces (13%) is the weakest one in resource factor; industrial structure (7%) and institute innovation (9.5%) positively improve the energy productivity.展开更多
Studies are conducted by using activated carbon process aimed at bromate removal from the raw water.Screening of activated carbon for bromate removal was performed in different activated carbons.GAC Merck possesses th...Studies are conducted by using activated carbon process aimed at bromate removal from the raw water.Screening of activated carbon for bromate removal was performed in different activated carbons.GAC Merck possesses the highest iodine number and surface area,the highest number of basic groups and Vmeso,thereby contains the highest adsorption velocity and adsorption capacity.Impact factors of bromate removal on activated carbon were studied.Through static absorption experiments we studied the effect of adsorption time,pH,temperature,anions and organic matter on bromate removal.With the decrease of pH,removal of bromate enhanced,suggests that it may be possible to increase bromate reduction through pH control.The increase of temperature will be favorable to adsorption of bromate on activated carbon.Anions and organic matter can inhibit the adsorption of bromate on activated carbon through competing active sites.Bromate removal can be improved by controlling key water quality parameters.展开更多
CO2 concentrations in different plant communities (larch, birch, lilac, and grassland) were measured during the growing season in the Heilongjiang Forest Botanical Garden to study diurnal variation, seasonal and ann...CO2 concentrations in different plant communities (larch, birch, lilac, and grassland) were measured during the growing season in the Heilongjiang Forest Botanical Garden to study diurnal variation, seasonal and annual dynamics and factors that impact CO2 concentration in different spaces. CO2 concentration in different communities in green lands had an obvious diurnal variation, chronically decreasing, and temperature influenced the lilac area and the grassland. Seasonally, CO2 was lowest in the larch green land (344.03 ±23.03 μmol/mol) and highest in the grassland (360.13 ± 22.43 μmol/mol). The overall trend in CO2 concentration was autumn 〉 spring 〉 summer; temperature is the main factor controlling variation in CO2 concentrations during the growing season; the CO2 concentration at the larch, birch, lilac, and grassland types of sites was negatively correlated with land surface temperature and air temperature, and the CO2 concentration at the larch and birch sites was positively correlated with atmospheric pressure. Without any obvious annual change law, further study and observation are needed.展开更多
In order to assess the capacity of Aquabacterium parvum sp. strain B6 for nitrate-dependent Fe(Ⅱ) oxidation,batch cultivation was conducted, and its ability to oxidize Fe(Ⅱ) coupled to nitrate reduction in the prese...In order to assess the capacity of Aquabacterium parvum sp. strain B6 for nitrate-dependent Fe(Ⅱ) oxidation,batch cultivation was conducted, and its ability to oxidize Fe(Ⅱ) coupled to nitrate reduction in the presence of diverse organic substrates was studied. Meanwhile, the nitrate-removal rate of B6 with various impact factors was further optimized by the response surface methodology(RSM). The results show that strain B6 is capable of utilizing different organic compounds as substrates for nitrate reduction. Compared with yeast extract, B6 showed a greater potential of chemical oxygen demand(COD)degradation and cell proliferation with acetate and glucose mediums, respectively, while citrate was not beneficial for this process due to its low consumption rate. RSM analysis demonstrated that the maximum nitrate-reduction rate of 30.64% could be achieved with an initial pH of 7.4,incubation temperature of 25.0 °C, and carbon source concentration of 266.10 mg/L.展开更多
In the railway bridge analysis and design method,dynamic train loads are regarded as static loads enhanced by an impact factor(IF).The IF coefficients for various railway bridges have been reported as a function of sp...In the railway bridge analysis and design method,dynamic train loads are regarded as static loads enhanced by an impact factor(IF).The IF coefficients for various railway bridges have been reported as a function of span length or frequency of the bridges in Eurocode(2003).However,these IF coefficient values neglect the effects of very high speeds(>200 km/h)and soil-structure interaction(SSI).In this work,a comprehensive study to assess the impact factor coefficients of mid-span vertical displacements for continuous and integral railway bridges subjected to high-speed moving loads is reported.Three different configurations,each for the three-dimensional(3D)continuous and integral bridge,are considered.Also,single-track(1-T)and two-track(2-T)“real train”loading cases for both these bridge types are considered.Subsequently,finite element analysis of the full-scale 3D bridge models,to identify their IF values,considering the effects of SSI for three different soil conditions,is conducted.The IF values obtained from the study for both bridge types are comparable and are greater than the values recommended by Eurocode(2003).The results reveal that with a loss of soil stiffness,the IF value reduces;thus,it confirms the importance of SSI analysis.展开更多
This paper focuses on the historical transition of human being's activities and the eco-environment in the upper reaches of Minjiang River. The history is divided into 4 periods, each with its own feature. During ...This paper focuses on the historical transition of human being's activities and the eco-environment in the upper reaches of Minjiang River. The history is divided into 4 periods, each with its own feature. During the period of nomad immigration, the top-line of the subalpine forest was forced downward by the expanding subalpine meadow. During the period of farming nationality immigration, the bottom-line of middle mountain forest had moved upward forced by the needs for land or timber of the increasing population in the valley basia During the period of the early exploiting, the focus resource was the timber. The total output was limited, comparing with the later period, because of the bad accessibility. But it was large enough to impact the forest ecosystem of the deforesting area. The recent 50 years is the crucial period of economic development and eco-environment degradation. This paper points out that the impact of human being's activities for environment lies on 3 factors: 1) physical features control the location and tendency eco-environmental change; 2) population and productivity control the scale and speed of eco-environmental change; 3) regional accessibility controls the time and location of eco-environmental change.展开更多
Nitrogen huff-n-puff(N_(2)HnP) appears to be an economical and high-efficiency enhanced oil recovery(EOR) technique for tight oil reservoirs.There is however a lack of understanding of the pore-level EOR performance o...Nitrogen huff-n-puff(N_(2)HnP) appears to be an economical and high-efficiency enhanced oil recovery(EOR) technique for tight oil reservoirs.There is however a lack of understanding of the pore-level EOR performance of N2HnP under tight reservoir conditions.In this work,a non-magnetic reactor was created and combined with a nuclear magnetic resonance(NMR) device for real-time monitoring of oil distribution in the HnP experiment.N_(2)HnP experiments were then performed in a tight sandstone core sample at a temperature of 353 K and an injection pressure≥ 24 MPa.The pore-level oil distribution under reservoir conditions was monitored and the EOR performance of N2HnP in specific pores was analyzed.The pore throat structures of the core sample and the phase behavior of the N_(2)-Oil system were analyzed to elucidate the EOR mechanism of N_(2)HnP.An oil recovery factor of 37.52% can be achieved after four cycles,which proves the EOR potential of N_(2)HnP for tight reservoirs.The highest recoveries after N_(2)HnP are obtained in the large pores,followed by the medium pores,the small pores,and finally the micro pores.Increases in soaking time and injection pressure resulted in slight and pronounced increases in oil recovery,respectively,both of which are mainly reflected in the first cycle.Specifically,increasing the soaking time only slightly improves the cumulative oil recovery in the small pores while increasing the injection pressure significantly improves the cumulative oil recovery in the small,medium,and large pores simultaneously.However,variations in both injection pressure and soaking time have a negligible effect on the cumulative oil recovery of the micro pores.展开更多
The Urban Heat Island Effect(UHI)has now become a commonly observed phenomenon worldwide.Indeed,it has become a significant environmental effect of urbanisation.In Malaysia,research results showed that UHI effects a...The Urban Heat Island Effect(UHI)has now become a commonly observed phenomenon worldwide.Indeed,it has become a significant environmental effect of urbanisation.In Malaysia,research results showed that UHI effects are very evident in several cities such as Kuala Lumpur and Putrajaya.UHI effect has long been observed to cause temperature of cities.展开更多
In this article, the quantitative impact and significance of factors on dust storm occurrence have been analyzed in detail, based on spring daily data sets of 17 meteorological factors and dust storm records during th...In this article, the quantitative impact and significance of factors on dust storm occurrence have been analyzed in detail, based on spring daily data sets of 17 meteorological factors and dust storm records during the period of 1954-2005 for 60 gauge stations distributed over Gansu Province of China. Results show that daily mean and maximum wind speeds and evaporation have a positive effect on dust storm occurrence, i.e., their increase can result in an increase of dust storm occurrence. Inversely, daily mean and minimum relative humidity, lowest surface air pressure, vapor pressure and number of sunny hours have a negative effect on dust storm occurrence. However, daily mean and highest surface air pressure; mean, highest and lowest surface air temperature; and precipitation of 20:00-08:00, 08:00-20:00 and 20:00-20:00 have a positive effect on dust storm occurrence in some places but negative in other places. On average, daily maximum and mean wind speeds, direction of the maximum wind, number of sunny hours and evaporation have a significant effect on dust storm occurrence in Gansu Province, but precipitation of 20:00--08:00, 08:00-20:00 and 20:00-20:00, and mean surface air pressure and temperature all have a minor influence upon dust storm occurrence.展开更多
Purpose: This work aims to consider the role and some of the 42-year history of the discipline impact factor(DIF) in evaluation of serial publications. Also, the original "symmetric" indicator called the &qu...Purpose: This work aims to consider the role and some of the 42-year history of the discipline impact factor(DIF) in evaluation of serial publications. Also, the original "symmetric" indicator called the "discipline susceptibility factor" is to be presented. Design/methodology/approach: In accordance with the purpose of the work, the methods are analytical interpretation of the scientific literature related to this problem as well as speculative explanations. The information base of the research is bibliometric publications dealing with impact, impact factor, discipline impact factor, and discipline susceptibility factor.Findings: Examples of the DIF application and modification of the indicator are given. It is shown why research and university libraries need to use the DIF to evaluate serials in conditions of scarce funding for subscription to serial publications, even if open access is available. The role of the DIF for evaluating journals by authors of scientific papers when choosing a good and right journal for submitting a paper is also briefly discussed. An original indicator "symmetrical" to the DIF(the "discipline susceptibility factor") and its differences from the DIF in terms of content and purpose of evaluation are also briefly presented.Research limitations: The selection of publications for the information base of the research did not include those in which the DIF was only mentioned, used partially or not for its original purpose. Restrictions on the length of the article to be submitted in this special issue of the JDIS also caused exclusion even a number of completely relevant publications. Consideration of the DIF is not placed in the context of describing other derivatives from the Garfield impact factor. Practical implications: An underrated bibliometric indicator, viz. the discipline impact factor is being promoted for the practical application. An original indicator "symmetrical" to DIF has been proposed in order of searching serial publications representing the external research fields that might fit for potential applications of the results of scientific activities obtained within the framework of the specific research field represented by the cited specialized journals. Both can be useful in research and university libraries in their endeavors to improve scientific information services. Also, both can be used for evaluating journals by authors of scientific papers when choosing a journal to submit a paper.Originality/value: The article substantiates the need to evaluate scientific serial publications in library activities—even in conditions of access to huge and convenient databases(subscription packages) and open access to a large number of serial publications. It gives a mini-survey of the history of one of the methods of such evaluation, and offers an original method for evaluating scientific serial publications.展开更多
To analyze the impact effect induced by vehicle-bridge coupling vibration during traffic congesting, hundreds and thousands of congestion scenarios consisting of various vehicle platoons were collected and used to dev...To analyze the impact effect induced by vehicle-bridge coupling vibration during traffic congesting, hundreds and thousands of congestion scenarios consisting of various vehicle platoons were collected and used to develop vehicle models as well as traffic congestion load models. Furthermore, the idling vehicle-bridge coupling model was established by the finite element method and the congestion models were applied to calculate dynamic impact factors. Compared with the value specified in Chinese codes, the calculated values were 1.15-2.67 times as large as the latter, which indicates the impact factors caused by idling vehicle-bridge coupling under congestion situations were much larger than those in normal traffic conditions. As a result, a calibration factor of 1.7 was recommended for bridge design or evaluation when considering vehicle-bridge coupling vibration under heavy traffic congestion. The proposed analytical model, analysis method, and results could also be beneficial references to further investigation in this field.展开更多
Ecological footprint(EF) has attracted much attention internationally as a potential indicator for sustainable development.In China,EF has also gained recognition in related fields and disciplines.Moreover,some schola...Ecological footprint(EF) has attracted much attention internationally as a potential indicator for sustainable development.In China,EF has also gained recognition in related fields and disciplines.Moreover,some scholars in these fields have proposed alternative methods to calculate EF and have made some progress.This paper,therefore,begins with the introduction and development of EF in China.However,the established methods of EF calculation hold some limitations,such as indicator variance and result abnormality.In order to resolve those problems,the authors make a further modification considering the demand of EF as a comprehensive indicator:1) More accurate analysis has been done to divide EF into several parts:imported EF,exported EF,and producible EF,which is the solution to the problem of abnormality in original EF results and can explain abnormal phenomena reasonably.2) Considering the actual situa-tion of Shanghai,amended equivalence factor is brought forward and a matrix is formed with equivalence factors.The measure can reduce the deviation between the fact and the results.3) The calculation compares local yield with global average yield to analyze the effects of yields.And based on local yields in different years,the results are more accurate.Finally,the calculation method is applied to calculating EF of Shanghai from 1980 to 2003,and the subsequent detailed analysis is presented.Available data and results suggest a statistically significant correlation coefficient between EF and GDP,population density and urbanization level.Through analyzing the process of calculating EF and its results,it can be seen that EF,as a macro-indicator,can not exactly indicate whether development within a region can meet the re-quests of sustainable development,which can be explained by the fact that the result of EF is impacted greatly by sub-jective factors including national policy,available technology,population,etc.Nevertheless,EF can demonstrate,at least to some degree,the regional status in terms of resources and energy consumption,as well as developmental potential.The calculation of EF,therefore,deserves further research to achieve more far-reaching significance in application.展开更多
Factors on degradation of chlorothalonil(CLT) in water by high frequency ultrasonic irradiation were investigated.The effects of initial concentration of chlorothalonil,dosages of tertiary butyl alcohol,humic acid and...Factors on degradation of chlorothalonil(CLT) in water by high frequency ultrasonic irradiation were investigated.The effects of initial concentration of chlorothalonil,dosages of tertiary butyl alcohol,humic acid and initial pH value on degradation of chlorothalonil,as well as the reaction mechanism were studied.The results reveal that chlorothalonil could be effectively degradated by ultrasonic irradiation.The reaction constant value kapp decreased from 0.014 1 to 0.010 2 min-1 with the initial concentration increasing from 50 to 400 μg/L during 180 min irradiation.Tertiary butyl alcohol had negative effect on chlorothalonil degradation,while lower concentration of humic acid promoted the sonolysis,and kapp declined with the further concentration increasing.The kapp varied little when the pH value ranged from 3.10 to 10.28.It may be concluded that mechanical and pyrolysis process played main roles on the degradation of chlorothalonil in ultrasonic irradiation rather than ·OH attack.The electrical energy per order(EEo) values for sonolysis degradation of CLT were also calculated to evaluate the cost of the process.展开更多
Elemental mercury(Hg0)re-emissions from slurries and solutions were evaluated in a lab-scale simulated scrubber.Oxidized mercury(Hg2 +)standard solution was injected into the simulated scrubber at a desired rate to si...Elemental mercury(Hg0)re-emissions from slurries and solutions were evaluated in a lab-scale simulated scrubber.Oxidized mercury(Hg2 +)standard solution was injected into the simulated scrubber at a desired rate to simulate absorbing and dissolving of Hg2 +in the flue gas across wet flue gas desulfurization(WFGD)systems. PS analytical mercury analyzer was used to continuously determine Hg0re-emission concentrations in the carrier gas from the scrubber.Sulfite ion in the slurry of CaSO3 was validated to reduce Hg 2+to Hg 0,while no Hg 0 re-emission occurred from slurries of CaSO4 and CaO.Transitional metal ions with low chemical valence such as Fe2 +,Pb 2+,Ni 2+, 2 AsO-and Cu +were used to prepare solutions with concentration levels of mmol·L-1.Reduction reaction of Hg2 +to Hg 0was observed from these solutions.Reduction capabilities for the different transitional metal ions in the solutions were:Pb2 +>Cu +>Fe 2+> 2 AsO->Ni 2+.展开更多
We discuss what document types account for the calculation of the journal impact factor (JIF) as published in the Journal Citation Reports (JCR). Based on a brief review of articles discussing how to predict JIFs and ...We discuss what document types account for the calculation of the journal impact factor (JIF) as published in the Journal Citation Reports (JCR). Based on a brief review of articles discussing how to predict JIFs and taking data differences between the Web of Science (WoS) and the JCR into account, we make our own predictions. Using data by cited-reference searching for Thomson Scientific's WoS, we predict 2007 impact factors (IFs) for several journals, such as Nature, Science, Learned Publishing and some Library and Information Sciences journals. Based on our colleagues' experiences we expect our predictions to be lower bounds for the official journal impact factors. We explain why it is useful to derive one's own journal impact factor.展开更多
The 2018 impact factors(IF)have just been released by Clarivate Analytics,Journal Citation Reports.Although IF has its flaws,it is an important factor that authors weigh during their submission of papers.A higher IF i...The 2018 impact factors(IF)have just been released by Clarivate Analytics,Journal Citation Reports.Although IF has its flaws,it is an important factor that authors weigh during their submission of papers.A higher IF indicates that the journal receives more attention in the scientific community and helps to attract more high-quality work,which consequently results in an increase in the visibility of the journal.We are delighted to announce on behalf of our editorial team that the two-year impact factor of Chinese Journal of Catalysis in 2018 is 4.914 ranking the 7th among the 71 international journals(9.86%,Q1)in the subject of applied chemistry.展开更多
基金This paper is part of the achievements of the CFL’s Undergraduate Project:An Investigation on the Influence of COVID-19 on Non intellectual Factors of College Students at USST in 2022.
文摘The outbreak of COVID-19 in December 2019 has exerted a wide and everlasting impact on the world,which has also influenced education enormously.The adjustment of objective learning environment during the COVID-19 pandemic makes the influence of non-intellectual factors on college students worthy of investigation,research and analysis.Based on this,we have launched a questionnaire survey on 500 college students who have witnessed the pandemic,and referred to related literature,network documents,news reports,contrast and analysis of college students’non-intelligence factors before and after the outbreak of the different levels of change,summing up some new measures to promote the development of college students’non-intelligence factors under the COVID-19 outbreak for online learning and autonomous learning.
基金l’UniversitéLaval for the financial support of his sabbatical year at Dipartimento di Bioscienze e Territorio,Universitàdegli Studi del Molise in Campobasso,Italy。
文摘This work presents a novel approach to the dynamic response analysis of a Euler-Bernoulli beam resting on a Winkler soil model and subjected to an impact loading.The approach considers that damping has much less importance in controlling the maximum response to impulsive loadings because the maximum response is reached in a very short time,before the damping forces can dissipate a significant portion of the energy input into the system.The development of two sine series solutions,relating to different types of impulsive loadings,one involving a single concentrated force and the other a distributed line load,are presented.This study revealed that when a simply supported Euler-Bernoulli beam,resting on a Winkler soil model,is subject to an impact load,the resulting vertical displacements,bending moments and shear forces produced along the span of the beam are considerably affected.In particular,the quantification of this effect is best observed,relative to the corresponding static solution,via an amplification factor.The computed impact amplification factors,for the sub-grade moduli used in this study,were in magnitude greater than 2,thus confirming the multiple-degree-of-freedom nature of the problem.
基金supported by the Henan Provincial Science and Technology Research Project under Grant(152102310295).
文摘A novel approach for analyzing coupled vibrations between vehicles and bridges is presented,taking into account spatiotemporal effects and mechanical phenomena resulting fromvehicle braking.Efficient modeling and solution of bridge vibrations induced by vehicle deceleration are realized using this method.The method’s validity and reliability are substantiated through numerical examples.A simply supported beam bridge with a corrugated steel web is taken as an example and the effects of parameters such as the initial vehicle speed,braking acceleration,braking location,and road surface roughness on the mid-span displacement and impact factor of the bridge are analyzed.The results show that vehicle braking significantly amplifies mid-span displacement and impact factor responses in comparison to uniform vehicular motion across the bridge.Notably,the influence of wheelto-bridge friction forces is of particular significance and cannot be overlooked.When the vehicle initiates braking near the middle of the span,both the mid-span displacement and impact factor of the bridge exhibit substantial increases,further escalating with higher braking acceleration.Under favorable road surface conditions,the midspan displacement and the impact factor during vehicle braking may exceed the design values stipulated by codes.It is important to note that road surface roughness exerts a more pronounced effect on the impact factor of the bridge in comparison to the effects of vehicle braking.
基金Supported by the National Special Fund for Basic Science and Technology of China(No.2012FY112500)the Public Science and Technology Research Funds Projects of Ocean in China(Nos.201305009,201505012)the Special Fund of Chinese Central Government for Basic Scientific Research Operations in Commonweal Research Institutes(No.FIO2015G13)
文摘Herbaceous plants are widely distributed on islands and where they exhibit spatial heterogeneity.Accurately identifying the impact factors that drive spatial heterogeneity can reveal typical island biodiversity patterns.Five southern islands in the Miaodao Archipelago,North China were studied herein.The spatial distribution of herbaceous plant diversity on these islands was analyzed,and the impact factors and their degree of impact on spatial heterogeneity were identified using CCA ordination and ANOVA.The results reveal 114 herbaceous plant species,belonging to 94 genera from 34 families in the50 plots sampled.The total species numbers on different islands were significantly positively correlated with island area,and the average a diversity was correlated with human activities,while the(3 diversity among islands was more affected by island area than mutual distances.Spatial heterogeneity within islands indicated that the diversities were generally high in areas with higher altitude,slope,total nitrogen,total carbon,and canopy density,and lower moisture content,pH,total phosphorus,total potassium,and aspect.Among the environmental factors,pH,canopy density,total K,total P,moisture content,altitude,and slope had significant gross effects,but only canopy density exhibited a significant net effect.Terrain affected diversity by restricting plantation,plantation in turn influenced soil properties and the two together affected diversity.Therefore,plantation was ultimately the fundamental driving factor for spatial heterogeneity in herbaceous plant diversity on the five islands.
文摘This article developed a decomposition model of energy productivity on the basis of the economic growth model. Four factors were considered which may influence China’s energy productivity according to this model: technology improvement, resource allocation structure, industrial structure and institute arrangement. Then, an econometric model was employed to test the four factors empirically on the basis of China’s statistical data from 1978 to 2004. Results indicated that capital deepening con- tributes the most (207%) to energy efficiency improvement, and impact from labor forces (13%) is the weakest one in resource factor; industrial structure (7%) and institute innovation (9.5%) positively improve the energy productivity.
基金Sponsored by High-Tech Research and Development Program (Grant No.2006AA06Z311)National Creative Research Groups (Grant No.50821002)+1 种基金National Science and Technology Support Funding (Grant No.2006BAJ08B0)Project Supported by Development Program for Outstanding Young Teachers in Harbin Institute of Technology(HITQNJS.2008.044)
文摘Studies are conducted by using activated carbon process aimed at bromate removal from the raw water.Screening of activated carbon for bromate removal was performed in different activated carbons.GAC Merck possesses the highest iodine number and surface area,the highest number of basic groups and Vmeso,thereby contains the highest adsorption velocity and adsorption capacity.Impact factors of bromate removal on activated carbon were studied.Through static absorption experiments we studied the effect of adsorption time,pH,temperature,anions and organic matter on bromate removal.With the decrease of pH,removal of bromate enhanced,suggests that it may be possible to increase bromate reduction through pH control.The increase of temperature will be favorable to adsorption of bromate on activated carbon.Anions and organic matter can inhibit the adsorption of bromate on activated carbon through competing active sites.Bromate removal can be improved by controlling key water quality parameters.
文摘CO2 concentrations in different plant communities (larch, birch, lilac, and grassland) were measured during the growing season in the Heilongjiang Forest Botanical Garden to study diurnal variation, seasonal and annual dynamics and factors that impact CO2 concentration in different spaces. CO2 concentration in different communities in green lands had an obvious diurnal variation, chronically decreasing, and temperature influenced the lilac area and the grassland. Seasonally, CO2 was lowest in the larch green land (344.03 ±23.03 μmol/mol) and highest in the grassland (360.13 ± 22.43 μmol/mol). The overall trend in CO2 concentration was autumn 〉 spring 〉 summer; temperature is the main factor controlling variation in CO2 concentrations during the growing season; the CO2 concentration at the larch, birch, lilac, and grassland types of sites was negatively correlated with land surface temperature and air temperature, and the CO2 concentration at the larch and birch sites was positively correlated with atmospheric pressure. Without any obvious annual change law, further study and observation are needed.
基金supported by a doctoral scholarship from the Chinese Scholarship Council (CSC)the National Natural Science Foundation of China (No. 51,478,140)
文摘In order to assess the capacity of Aquabacterium parvum sp. strain B6 for nitrate-dependent Fe(Ⅱ) oxidation,batch cultivation was conducted, and its ability to oxidize Fe(Ⅱ) coupled to nitrate reduction in the presence of diverse organic substrates was studied. Meanwhile, the nitrate-removal rate of B6 with various impact factors was further optimized by the response surface methodology(RSM). The results show that strain B6 is capable of utilizing different organic compounds as substrates for nitrate reduction. Compared with yeast extract, B6 showed a greater potential of chemical oxygen demand(COD)degradation and cell proliferation with acetate and glucose mediums, respectively, while citrate was not beneficial for this process due to its low consumption rate. RSM analysis demonstrated that the maximum nitrate-reduction rate of 30.64% could be achieved with an initial pH of 7.4,incubation temperature of 25.0 °C, and carbon source concentration of 266.10 mg/L.
文摘In the railway bridge analysis and design method,dynamic train loads are regarded as static loads enhanced by an impact factor(IF).The IF coefficients for various railway bridges have been reported as a function of span length or frequency of the bridges in Eurocode(2003).However,these IF coefficient values neglect the effects of very high speeds(>200 km/h)and soil-structure interaction(SSI).In this work,a comprehensive study to assess the impact factor coefficients of mid-span vertical displacements for continuous and integral railway bridges subjected to high-speed moving loads is reported.Three different configurations,each for the three-dimensional(3D)continuous and integral bridge,are considered.Also,single-track(1-T)and two-track(2-T)“real train”loading cases for both these bridge types are considered.Subsequently,finite element analysis of the full-scale 3D bridge models,to identify their IF values,considering the effects of SSI for three different soil conditions,is conducted.The IF values obtained from the study for both bridge types are comparable and are greater than the values recommended by Eurocode(2003).The results reveal that with a loss of soil stiffness,the IF value reduces;thus,it confirms the importance of SSI analysis.
基金Supported by the Knowledge Innovative program of Chinese Academy of Sciences(KSCX1-07-03)
文摘This paper focuses on the historical transition of human being's activities and the eco-environment in the upper reaches of Minjiang River. The history is divided into 4 periods, each with its own feature. During the period of nomad immigration, the top-line of the subalpine forest was forced downward by the expanding subalpine meadow. During the period of farming nationality immigration, the bottom-line of middle mountain forest had moved upward forced by the needs for land or timber of the increasing population in the valley basia During the period of the early exploiting, the focus resource was the timber. The total output was limited, comparing with the later period, because of the bad accessibility. But it was large enough to impact the forest ecosystem of the deforesting area. The recent 50 years is the crucial period of economic development and eco-environment degradation. This paper points out that the impact of human being's activities for environment lies on 3 factors: 1) physical features control the location and tendency eco-environmental change; 2) population and productivity control the scale and speed of eco-environmental change; 3) regional accessibility controls the time and location of eco-environmental change.
基金financial support from the National Natural Science Foundation of China(52074319)the Strategic Cooperation Technology Project of CNPC(ZLZX2020-01-08)the Science Foundation of China University of Petroleum-Beijing(2462021QNXZ008)
文摘Nitrogen huff-n-puff(N_(2)HnP) appears to be an economical and high-efficiency enhanced oil recovery(EOR) technique for tight oil reservoirs.There is however a lack of understanding of the pore-level EOR performance of N2HnP under tight reservoir conditions.In this work,a non-magnetic reactor was created and combined with a nuclear magnetic resonance(NMR) device for real-time monitoring of oil distribution in the HnP experiment.N_(2)HnP experiments were then performed in a tight sandstone core sample at a temperature of 353 K and an injection pressure≥ 24 MPa.The pore-level oil distribution under reservoir conditions was monitored and the EOR performance of N2HnP in specific pores was analyzed.The pore throat structures of the core sample and the phase behavior of the N_(2)-Oil system were analyzed to elucidate the EOR mechanism of N_(2)HnP.An oil recovery factor of 37.52% can be achieved after four cycles,which proves the EOR potential of N_(2)HnP for tight reservoirs.The highest recoveries after N_(2)HnP are obtained in the large pores,followed by the medium pores,the small pores,and finally the micro pores.Increases in soaking time and injection pressure resulted in slight and pronounced increases in oil recovery,respectively,both of which are mainly reflected in the first cycle.Specifically,increasing the soaking time only slightly improves the cumulative oil recovery in the small pores while increasing the injection pressure significantly improves the cumulative oil recovery in the small,medium,and large pores simultaneously.However,variations in both injection pressure and soaking time have a negligible effect on the cumulative oil recovery of the micro pores.
基金funded by Grand Challenge-SUS(Sustainability Science)Grants GC002C-15SUS and GC002A-15SUS
文摘The Urban Heat Island Effect(UHI)has now become a commonly observed phenomenon worldwide.Indeed,it has become a significant environmental effect of urbanisation.In Malaysia,research results showed that UHI effects are very evident in several cities such as Kuala Lumpur and Putrajaya.UHI effect has long been observed to cause temperature of cities.
基金supported by the Hundred Talent Project of Chinese Academy of Sciences granted to Dr. Y. Yuthe Primary Natural Sciences Foundation of China (40633014) granted to Professor S.H. Lü
文摘In this article, the quantitative impact and significance of factors on dust storm occurrence have been analyzed in detail, based on spring daily data sets of 17 meteorological factors and dust storm records during the period of 1954-2005 for 60 gauge stations distributed over Gansu Province of China. Results show that daily mean and maximum wind speeds and evaporation have a positive effect on dust storm occurrence, i.e., their increase can result in an increase of dust storm occurrence. Inversely, daily mean and minimum relative humidity, lowest surface air pressure, vapor pressure and number of sunny hours have a negative effect on dust storm occurrence. However, daily mean and highest surface air pressure; mean, highest and lowest surface air temperature; and precipitation of 20:00-08:00, 08:00-20:00 and 20:00-20:00 have a positive effect on dust storm occurrence in some places but negative in other places. On average, daily maximum and mean wind speeds, direction of the maximum wind, number of sunny hours and evaporation have a significant effect on dust storm occurrence in Gansu Province, but precipitation of 20:00--08:00, 08:00-20:00 and 20:00-20:00, and mean surface air pressure and temperature all have a minor influence upon dust storm occurrence.
文摘Purpose: This work aims to consider the role and some of the 42-year history of the discipline impact factor(DIF) in evaluation of serial publications. Also, the original "symmetric" indicator called the "discipline susceptibility factor" is to be presented. Design/methodology/approach: In accordance with the purpose of the work, the methods are analytical interpretation of the scientific literature related to this problem as well as speculative explanations. The information base of the research is bibliometric publications dealing with impact, impact factor, discipline impact factor, and discipline susceptibility factor.Findings: Examples of the DIF application and modification of the indicator are given. It is shown why research and university libraries need to use the DIF to evaluate serials in conditions of scarce funding for subscription to serial publications, even if open access is available. The role of the DIF for evaluating journals by authors of scientific papers when choosing a good and right journal for submitting a paper is also briefly discussed. An original indicator "symmetrical" to the DIF(the "discipline susceptibility factor") and its differences from the DIF in terms of content and purpose of evaluation are also briefly presented.Research limitations: The selection of publications for the information base of the research did not include those in which the DIF was only mentioned, used partially or not for its original purpose. Restrictions on the length of the article to be submitted in this special issue of the JDIS also caused exclusion even a number of completely relevant publications. Consideration of the DIF is not placed in the context of describing other derivatives from the Garfield impact factor. Practical implications: An underrated bibliometric indicator, viz. the discipline impact factor is being promoted for the practical application. An original indicator "symmetrical" to DIF has been proposed in order of searching serial publications representing the external research fields that might fit for potential applications of the results of scientific activities obtained within the framework of the specific research field represented by the cited specialized journals. Both can be useful in research and university libraries in their endeavors to improve scientific information services. Also, both can be used for evaluating journals by authors of scientific papers when choosing a journal to submit a paper.Originality/value: The article substantiates the need to evaluate scientific serial publications in library activities—even in conditions of access to huge and convenient databases(subscription packages) and open access to a large number of serial publications. It gives a mini-survey of the history of one of the methods of such evaluation, and offers an original method for evaluating scientific serial publications.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51708069)the Natural Science Foundation of Chongqing(Grant No.cstcstc2018jcyjA2535)。
文摘To analyze the impact effect induced by vehicle-bridge coupling vibration during traffic congesting, hundreds and thousands of congestion scenarios consisting of various vehicle platoons were collected and used to develop vehicle models as well as traffic congestion load models. Furthermore, the idling vehicle-bridge coupling model was established by the finite element method and the congestion models were applied to calculate dynamic impact factors. Compared with the value specified in Chinese codes, the calculated values were 1.15-2.67 times as large as the latter, which indicates the impact factors caused by idling vehicle-bridge coupling under congestion situations were much larger than those in normal traffic conditions. As a result, a calibration factor of 1.7 was recommended for bridge design or evaluation when considering vehicle-bridge coupling vibration under heavy traffic congestion. The proposed analytical model, analysis method, and results could also be beneficial references to further investigation in this field.
基金Under the auspices of the Major State Basic Research Development Program of China (973 Program) (No 2005CB724201)
文摘Ecological footprint(EF) has attracted much attention internationally as a potential indicator for sustainable development.In China,EF has also gained recognition in related fields and disciplines.Moreover,some scholars in these fields have proposed alternative methods to calculate EF and have made some progress.This paper,therefore,begins with the introduction and development of EF in China.However,the established methods of EF calculation hold some limitations,such as indicator variance and result abnormality.In order to resolve those problems,the authors make a further modification considering the demand of EF as a comprehensive indicator:1) More accurate analysis has been done to divide EF into several parts:imported EF,exported EF,and producible EF,which is the solution to the problem of abnormality in original EF results and can explain abnormal phenomena reasonably.2) Considering the actual situa-tion of Shanghai,amended equivalence factor is brought forward and a matrix is formed with equivalence factors.The measure can reduce the deviation between the fact and the results.3) The calculation compares local yield with global average yield to analyze the effects of yields.And based on local yields in different years,the results are more accurate.Finally,the calculation method is applied to calculating EF of Shanghai from 1980 to 2003,and the subsequent detailed analysis is presented.Available data and results suggest a statistically significant correlation coefficient between EF and GDP,population density and urbanization level.Through analyzing the process of calculating EF and its results,it can be seen that EF,as a macro-indicator,can not exactly indicate whether development within a region can meet the re-quests of sustainable development,which can be explained by the fact that the result of EF is impacted greatly by sub-jective factors including national policy,available technology,population,etc.Nevertheless,EF can demonstrate,at least to some degree,the regional status in terms of resources and energy consumption,as well as developmental potential.The calculation of EF,therefore,deserves further research to achieve more far-reaching significance in application.
基金Project(2008ZX07421-002) supported by the National Major Project of Science & Technology Ministry of ChinaProject(2008AA06A412) supported by the National High Technology Research and Development Program of ChinaProject(20009-K7-4) supported by the Research and Development of Ministry of Housing and Urban-Rural Development of China
文摘Factors on degradation of chlorothalonil(CLT) in water by high frequency ultrasonic irradiation were investigated.The effects of initial concentration of chlorothalonil,dosages of tertiary butyl alcohol,humic acid and initial pH value on degradation of chlorothalonil,as well as the reaction mechanism were studied.The results reveal that chlorothalonil could be effectively degradated by ultrasonic irradiation.The reaction constant value kapp decreased from 0.014 1 to 0.010 2 min-1 with the initial concentration increasing from 50 to 400 μg/L during 180 min irradiation.Tertiary butyl alcohol had negative effect on chlorothalonil degradation,while lower concentration of humic acid promoted the sonolysis,and kapp declined with the further concentration increasing.The kapp varied little when the pH value ranged from 3.10 to 10.28.It may be concluded that mechanical and pyrolysis process played main roles on the degradation of chlorothalonil in ultrasonic irradiation rather than ·OH attack.The electrical energy per order(EEo) values for sonolysis degradation of CLT were also calculated to evaluate the cost of the process.
基金Supported by the US Agency for International Development(USAID)cooperation agreement(486-A-00-06-000140-00)
文摘Elemental mercury(Hg0)re-emissions from slurries and solutions were evaluated in a lab-scale simulated scrubber.Oxidized mercury(Hg2 +)standard solution was injected into the simulated scrubber at a desired rate to simulate absorbing and dissolving of Hg2 +in the flue gas across wet flue gas desulfurization(WFGD)systems. PS analytical mercury analyzer was used to continuously determine Hg0re-emission concentrations in the carrier gas from the scrubber.Sulfite ion in the slurry of CaSO3 was validated to reduce Hg 2+to Hg 0,while no Hg 0 re-emission occurred from slurries of CaSO4 and CaO.Transitional metal ions with low chemical valence such as Fe2 +,Pb 2+,Ni 2+, 2 AsO-and Cu +were used to prepare solutions with concentration levels of mmol·L-1.Reduction reaction of Hg2 +to Hg 0was observed from these solutions.Reduction capabilities for the different transitional metal ions in the solutions were:Pb2 +>Cu +>Fe 2+> 2 AsO->Ni 2+.
文摘We discuss what document types account for the calculation of the journal impact factor (JIF) as published in the Journal Citation Reports (JCR). Based on a brief review of articles discussing how to predict JIFs and taking data differences between the Web of Science (WoS) and the JCR into account, we make our own predictions. Using data by cited-reference searching for Thomson Scientific's WoS, we predict 2007 impact factors (IFs) for several journals, such as Nature, Science, Learned Publishing and some Library and Information Sciences journals. Based on our colleagues' experiences we expect our predictions to be lower bounds for the official journal impact factors. We explain why it is useful to derive one's own journal impact factor.
文摘The 2018 impact factors(IF)have just been released by Clarivate Analytics,Journal Citation Reports.Although IF has its flaws,it is an important factor that authors weigh during their submission of papers.A higher IF indicates that the journal receives more attention in the scientific community and helps to attract more high-quality work,which consequently results in an increase in the visibility of the journal.We are delighted to announce on behalf of our editorial team that the two-year impact factor of Chinese Journal of Catalysis in 2018 is 4.914 ranking the 7th among the 71 international journals(9.86%,Q1)in the subject of applied chemistry.