Land use/land cover represents the interactive and comprehensive influences between human activities and natural conditions,leading to potential conflicts among natural and human-related issues as well as among stakeh...Land use/land cover represents the interactive and comprehensive influences between human activities and natural conditions,leading to potential conflicts among natural and human-related issues as well as among stakeholders.This study introduced economic standards for farmers.A hybrid approach(CA-ABM)of cellular automaton(CA)and an agent-based model(ABM)was developed to effectively deal with social and land-use synergic issues to examine human–environment interactions and projections of land-use conversions for a humid basin in south China.Natural attributes and socioeconomic data were used to analyze land use/land cover and its drivers of change.The major modules of the CA-ABM are initialization,migration,assets,land suitability,and land-use change decisions.Empirical estimates of the factors influencing the urban land-use conversion probability were captured using parameters based on a spatial logistic regression(SLR)model.Simultaneously,multicriteria evaluation(MCE)and Markov models were introduced to obtain empirical estimates of the factors affecting the probability of ecological land conversion.An agent-based CA-SLR-MCE-Markov(ABCSMM)land-use conversion model was proposed to explore the impacts of policies on land-use conversion.This model can reproduce observed land-use patterns and provide links for forest transition and urban expansion to land-use decisions and ecosystem services.The results demonstrated land-use simulations under multi-policy scenarios,revealing the usefulness of the model for normative research on land-use management.展开更多
Irrigation water became the limiting factor to the persistent improvement of grain production. Based on the data from Gannan County, a semiarid area in the west of Heilongjiang Province, the present situation of the d...Irrigation water became the limiting factor to the persistent improvement of grain production. Based on the data from Gannan County, a semiarid area in the west of Heilongjiang Province, the present situation of the development and utilization of water resources and the suitable water saving irrigation mode were analyzed by using SPA model, which was significant to the efficient and rational utilization of water resources and the improvement of agriculture productivity. The result showed that the model could be applied well to the assessment of development and utilization of water resources and the multi-project optimal selection. Through calculation, it could be found that the utilization of water resources in Gannan County was still in the primary stage, and the integration technology of the optimized water saving irrigation should be combined to support the sustainable development of agriculture in the semiarid area.展开更多
The paper analyzed the seasonal variation of the concentrations of Cr, Mn, A1, N, P, As, Ba, Ca, Cu, Fe, Mg, and K in South Lake Cyohoha water using spectroscopic technique. Water samples were taken monthly at Ngenda,...The paper analyzed the seasonal variation of the concentrations of Cr, Mn, A1, N, P, As, Ba, Ca, Cu, Fe, Mg, and K in South Lake Cyohoha water using spectroscopic technique. Water samples were taken monthly at Ngenda, Karehe and Nyamabuye stations from January 2009 to December 2010. The results showed that the concentrations of aluminum, nitrogen, potassium, arsenic, phosphorous, manganese, chromium, barium and copper were high during the raining season and low during the dry season, while calcium, iron and magnesium varied independently with seasonal change. The results of conductivity and pH also confirmed the effects of seasonal change on the quality of water in the South Lake Cyohoha since the highest value of conductivity was found during the raining season, while the smallest was observed during the dry season, for pH the highest number was noticed during the dry season and the lowest during the raining season.展开更多
Different irrigation schemes have different effects on water consumption in rice production.However,few studies have been conducted on the water consumption processes between dry direct seeding rice and transplanting ...Different irrigation schemes have different effects on water consumption in rice production.However,few studies have been conducted on the water consumption processes between dry direct seeding rice and transplanting rice under different irrigation schemes.Water consumption process,water use efficiency and correlation effect of water consumption on yield under different planting models in rice production were investigated in northeast China in 2018.Seven treatments were implemented:drip irrigation dry direct seeding rice(DDSR),wet irrigation dry direct seeding rice(WDSR),flooded irrigation dry direct seeding rice(FDSR),transplanting flooded rice(TFR),controlled irrigation transplanting rice(CTR),intermittent irrigation transplanting rice(ITR)and wet irrigation transplanting rice(WTR).Among them,TFR was the control.The results showed that the peaks of the water consumption amount,intensity and its modulus coefficient of the seven treatments all appeared in the middle tillering and the jointing booting stages.The total water consumption amount(ET)and average water consumption intensity of DDSR,WDSR,FDSR and WTR were lower than those of TFR,CTR and ITR.The maximum water use efficiency of yield(WUEy)occurred in DDSR with a value of 3.8 kg·m^(-3).WUEy of DDSR,WDSR and FDSR were significantly higher than those of TFR,CTR and ITR.In the middle tillering and the heading and flowering stages,the water consumption amount of each treatment had a positive effect on yield formation,and the water consumption amount in the late tillering stage had a negative effect on yield formation.The relationship between ET and yield(Y)of dry direct seeding and transplanting planting models showed a quadratic function curve.ET of transplanting planting model had a significant positive impact on Y,and ET of dry direct seeding planting model had no impact on Y.DDSR had the least total water consumption of 199.8 mm·m^(-2),the lowest water consumption intensity of 2.0 mm·d^(-1) and the greatest water use efficiency of 3.8 kg·m^(-3),which suggested that DDSR had the most significant water saving effect.The combination of dry direct seeding planting model and drip irrigation scheme would be a good option for determining a water-saving rice planting model in northeast China.展开更多
Up to 1.5wt%of Cr(Ⅲ)salts(CrCl_(3),and Cr_(2)O_(3))and Cr(Ⅵ)salts(Na_(2)CrO_(4),and CaCr_(2)O_(7))were incorporated into red mud-based geopolymers,respectively.The solidification/stabilization,compressive strength,a...Up to 1.5wt%of Cr(Ⅲ)salts(CrCl_(3),and Cr_(2)O_(3))and Cr(Ⅵ)salts(Na_(2)CrO_(4),and CaCr_(2)O_(7))were incorporated into red mud-based geopolymers,respectively.The solidification/stabilization,compressive strength,and durability of the Cr-containing geopolymers were investigated.The experimental results indicate that the red mud-based geopolymer could effectively solidify/stabilize different types of Cr salts with solidification/stabilization rates of above 99.61%.Geopolymers are environmentally safe when the dosage of CaCr_(2)O_(7)is≤1.0wt%,or the dosage of CrCl_(3),Cr_(2)O_(3),and Na_(2)CrO_(4)is≤1.5wt%,respectively.The effects of Cr salts on the compressive strength varies with the type and content of Cr salts.The freeze-thaw cycle is more destructive to geopolymer properties than sulfate attack or acid rain erosion.The solidification/stabilization of Cr is mainly attributed to the following reasons:a)The chemical binding of Cr is related to the formation of Cr-containing hydrates(eg,magnesiochromite((Mg,Fe)(Cr,Al)_(2)O_(4)))and doping into N-A-S-H gel and C-A-S-H gel framework;b)The physical effect is related to the encapsulation by the hydration products(e g,N-A-S-H gel and C-A-S-H gel).This study provides a reference for the treatment of hazardous Cr-containing wastes by solid waste-based geopolymers.展开更多
The deterioration of the performance of offshore bridges is particularly prominent due to the complex natural environment,including the coupling effects of earthquake and seawater erosion.In particular,bridge piers ar...The deterioration of the performance of offshore bridges is particularly prominent due to the complex natural environment,including the coupling effects of earthquake and seawater erosion.In particular,bridge piers are the main energy-consuming and load-bearing components,so that excellent seismic capacity of bridge piers is the key to avoiding bridge damage.Although earthquake resistant behavior of ordinary reinforced concrete bridge piers(ordinary pier)can be improved by increasing the section size and reinforcement ratio of piers,the improvement of the earthquake resistant behavior is limited.To further improve the earthquake resistant behavior of bridge piers,high-tensile reinforcement engineered cementitious composite(ECC)bridge piers are utilized and time-varying seismic fragility analysis are conducted in this study.The refined model of a bridge pier is built by OpenSees.First,the influence of ECC replacement height on pier curvature is analyzed to determine the reasonable ECC height.Then,the time-varying fragility analysis of high-tensile reinforcement ECC piers(ECC composite piers)with durability damage are evaluated considering the time-varying law of materials.Four damage states,slight damage,moderate damage,extensive damage and complete collapse,are utilized in the study.These fragility curves indicate the durability damage can debase the earthquake resistant behavior of piers continually,the exceedance probability of the same state of destruction increases with the increase of peak ground acceleration(PGA)and service time of pier.The results also indicate that the corrosion level of chloride ion to pier is small during the early service period,and the bridge pier vulnerable curve is similar to that of the new bridge pier.As the level of chlorine ion corrosion deepens,transcendental probability is increased.Compared with the ordinary pier,the exceedance probability in each limit state of ECC composite piers is significantly reduced.The proposed ECC composite pies leads to better realistic time-varying earthquake resistant behavior.展开更多
Using six ice-tethered buoys deployed in 2012,we analyzed sea ice motion in the central Arctic Ocean and Fram Strait.The two-hourly buoy-derived ice velocities had a magnitude range of 0.010.80 m s 1,although ice velo...Using six ice-tethered buoys deployed in 2012,we analyzed sea ice motion in the central Arctic Ocean and Fram Strait.The two-hourly buoy-derived ice velocities had a magnitude range of 0.010.80 m s 1,although ice velocities within the Arctic Basin were generally less than 0.4 m s 1.Complex Fourier transformation showed that the amplitudes of the sea ice velocities had a non-symmetric inertial oscillation.These inertial oscillations were characterized by a strong peak at a frequency of approximately 2 cycle d 1 on the Fourier velocity spectrum.Wind was a main driving force for ice motion,characterized by a linear relationship between ice velocity and 10-m wind speed.Typically,the ice velocity was about 1.4%of the 10-m wind speed.Our analysis of ice velocity and skin temperature showed that ice velocity increased by nearly 2%with each 10℃increase in skin temperature.This was likely related to weakened ice strength under increasing temperature.The ice-wind turning angle was also correlated with 10-m wind speed and skin temperature.When the wind speed was less than 12 m s 1 or skin temperature was less than 30℃,the ice-wind turning angle decreased with either increasing wind speed or skin temperature.Clearly,sea ice drift in the central Arctic Ocean and Fram Strait is dependent upon seasonal changes in both temperature and wind speed.展开更多
In this paper,a notched three-point bending test is used to study the fracture performance of the short basalt fiber bundle reinforced concrete(SBFBRC).To compare and analyze the enhancement effect of different diamet...In this paper,a notched three-point bending test is used to study the fracture performance of the short basalt fiber bundle reinforced concrete(SBFBRC).To compare and analyze the enhancement effect of different diameters and different content of basalt fiber bundles on the fracture performance of concrete,some groups are set up,and the P-CMOD curves of each group of specimens are measured,and the fracture toughness and fracture energy of each control group are calculated.The fracture toughness and fracture energy are two important fracture performance parameters to study the effect and law of the new basalt fiber bundles on the fracture performance of concrete.The research results show that the diameter and content of the new basalt fiber bundles have a certain effect on the fracture performance of concrete.With the increase of the content of basalt fiber bundles,the peak load,crack initiation toughness,instability toughness and fracture energy of SBFBRC are greatly improved compared with the benchmark group.When the fiber bundle diameter is 0.2 mm,the peak load increases by 69.5%compared with the reference group.The instability toughness reaches its maximum value at 0.2 mm diameter,which is 59.7%higher than the benchmark.展开更多
Air movement dries surfaces by increasing evaporation and convection,which may prevent mould growth.Cladosporium sp.is used as the test organism(dominant fungi in the envelope of rural houses in hot summer and warm wi...Air movement dries surfaces by increasing evaporation and convection,which may prevent mould growth.Cladosporium sp.is used as the test organism(dominant fungi in the envelope of rural houses in hot summer and warm winter areas),and the effect of fans on inhibiting mould growth on building materials is investigated.Surface mould growth on materials was simulated and compared after rain leakage and surface condensation,and spore germination was studied in high humidity,with or without airflow.The results are as follows:(1)Airflow has an evident inhibitory effect on mould growth on wet building materials.This observation was linked to the availability of moisture content in the building materials.(2)Airflow can slow the appearance of visual mould on the material surface.Mould did not appear on the gypsum surface due to the airflow,and mould growth on a wood surface was delayed for about two days.(3)Periodically,spore eluates were examined by electron microscopy to determine the stage of spore germination,and it was found that airflow delayed mould spore germination for about 2-3 days.展开更多
For optimizing the water-use structure and increasing plantation benefit of unit water consumption,a multi-objective model for water resources utilization was established based on fractional programming(FP).Meanwhile,...For optimizing the water-use structure and increasing plantation benefit of unit water consumption,a multi-objective model for water resources utilization was established based on fractional programming(FP).Meanwhile,considering the stochasticity of water availability in the study area,the impact of the risk factor(λ)from a quantitative and qualitative perspective was analyzed.The chance-constrained programming(CCP)and conditional value-at-risk(CVaR)models were introduced into five important major grain production areas in Sanjiang Plain,and the crop planting structure under this condition was optimized.The results showed that,after optimization,overall benefit of cultivation increased from 42.07 billion Yuan to 42.47 billion Yuan,water consumption decreased from 15.90 billion m3 to 11.95 billion m3,the plantation benefit of unit water consumption increased from 2.65 Yuan/m3 to 3.55 Yuan/m3.Furthermore,the index of water consumption,benefit of cultivation and plantation benefit of unit water consumption showed an increasing trend with the increase of violation likelihood.However,through the quantification ofλfrom an economic perspective,the increasing ofλcould not enhance plantation benefit of unit water consumption significantly.展开更多
Coordinated and orderly water and land resource system is vital to ensure the economic and social development of a region.Grain production in Heilongjiang Province has increased consecutively every year since 2003,and...Coordinated and orderly water and land resource system is vital to ensure the economic and social development of a region.Grain production in Heilongjiang Province has increased consecutively every year since 2003,and numerous water and land resource-related problems have become increasingly prominent and have had significant adverse effects on social and economic development and stability in the region.In this study,Heilongjiang Province and its 13 prefecture-level cities were selected as the study area,and the degrees of coordination of the social,economic and ecological subsystems were evaluated using periphery theory and the theory of synergetics.To ensure that the assessment was objective and accurate,weights were calculated using the projection pursuit technique,and similarity degrees were calculated using a modified(by introducing the chi-square distance)order of preference by similarity to ideal solution(TOPSIS)technique.Moreover,to reflect the variations in the overall degree of coordination in Heilongjiang Province,the risk level of the coordination of the water and land resource system was predicted through the year 2020 using a dynamic neural network.This study provides a reference for establishing effective and balanced coordination between society and water and land resources.展开更多
In order to investigate the transfer and migration behavior of polycyclic aromatic hydrocarbons(PAHs)in soil with long-term wastewater irrigation,Groundwater Ubiquity Score(GUS)and fugacity method were respectively us...In order to investigate the transfer and migration behavior of polycyclic aromatic hydrocarbons(PAHs)in soil with long-term wastewater irrigation,Groundwater Ubiquity Score(GUS)and fugacity method were respectively used to assess the potential entry into the groundwater and transfer capacity of PAHs.The results of assessment using GUS show that there is significant correlation between the GUS and organic carbon sorption coefficient(KOC)for PAHs and a simple assessment method with KOC was referred to evaluate contamination of groundwater.Applying fugacity method,evaluation results of transfer and migration of PAHs in soil suggest that the PAHs accumulation in the soil through long-term wastewater irrigation could be re-volatilized as secondary emission sources to atmosphere for the Low Molecular Weight(LMW)PAHs,in contrast to High Molecular Weight(HMW)PAHs for which the soil remains a sink that could absorb more PAHs.The net volatilisation flux was 0.39 g/d in upland and 0.32 g/d in paddy for LMW Nap(Naphthalene),and 0.97×10^(-3)g/d in upland and 0.37×10^(-3)g/d in paddy for LMW Phe(Phenanthrene).The net deposition was 0.72×10^(-4)g/d in upland and 0.10×10^(-3)g/d in paddy for HMW Fla(Fluoranthene),and 0.22×10^(-4)g/d in upland and 0.20×10^(-4)g/d in paddy for HMW Bap(Benzo[a]pyrene).Sensitivities of the model estimates to input parameters were tested,and the sensitivity coefficient was defined for the test.The most influential parameters were the volumes of the air,water,and organic carbon fractions in soil and the thickness of the soil.展开更多
Nowadays,iron ions as a ubiquitous heavy metal pollutant are gradually concerned and the convenient and quick removal of excessive iron ions in groundwater has become a major challenge for the safety of drinking water...Nowadays,iron ions as a ubiquitous heavy metal pollutant are gradually concerned and the convenient and quick removal of excessive iron ions in groundwater has become a major challenge for the safety of drinking water.In this study,boron-doped biochar(B-BC)was successfully prepared at various preparation conditions with the addition of boric acid.The as-prepared material has a more developed pore structure and a larger specific surface area(up to 897.97 m2/g).A series of characterization results shows that boric acid effectively activates biochar,and boron atoms are successfully doped on biochar.Compared with the ratio of raw materials,the pyrolysis temperature has a greater influence on the amount of boron doping.Based on Langmuir model,the maximum adsorption capacity of 800 B-BC1:2 at25℃,40℃,55℃ are 50.02 mg/g,95.09 mg/g,132.78 mg/g,respectively.Pseudo-second-order kinetic model can better describe the adsorption process,the adsorption process is mainly chemical adsorption.Chemical complexation,ions exchange,and co-precipitation may be the main mechanisms for Fe2+removal.展开更多
To determine the influence of agricultural meteorological disasters on agriculture in Heilongjiang Province,the disaster areas associated with different types of disasters and their variation characteristics were anal...To determine the influence of agricultural meteorological disasters on agriculture in Heilongjiang Province,the disaster areas associated with different types of disasters and their variation characteristics were analyzed based on the statistical data of agricultural disasters from 1983 to 2013 in Heilongjiang Province,China.The moving average and the Mann-Kendall test were applied to identify the variation trends of drought,flooding,hailstorms and freezing(based on the disaster ratio and the disaster intensity index).Then,the Morlet wavelet analysis method was used to identify the periodicity of these four kinds of agricultural meteorological disasters.Finally,a fuzzy comprehensive evaluation method was adopted to analyze the degrees of agricultural loss induced by these disasters.The following results were obtained:1)The disaster ratio and disaster intensity index for drought exhibited increasing trends;the disaster ratio and disaster intensity index for flooding exhibited decreasing trends;for hailstorms,the disaster ratio exhibited no obvious trend of change,whereas the disaster intensity index exhibited an increasing trend;and for freezing,the disaster ratio also exhibited no obvious trend of change,whereas the disaster intensity index exhibited a decreasing trend.2)Mutation points were observed in the disaster ratio series for drought,flooding and hailstorms,whereas no mutation point was evident in the disaster ratio series for freezing.3)Multiple time-scale characteristics were observed in the disaster ratio series for all four types of agricultural meteorological disasters.Furthermore,the disaster ratio series for the different types of disasters had different main periodicities.4)From the perspective of the degree of agricultural loss induced by each type of disaster,drought was identified as the most severe type of agricultural meteorological disaster,followed by flooding,freezing,and hailstorms.The degree of agricultural loss caused by each type of disaster was different during different periods.Finally,based on the results,several strategies were identified for mitigating the effect of agricultural meteorological disasters in Heilongjiang Province.展开更多
Based on a winter field experiment between 2016 and 2017,four treatments(bare land(BL),natural snowfall coverage(NS),5-cm-deep straw+natural snowfall coverage(SC5),and 10-cm-deep straw+natural snowfall coverage(SC10))...Based on a winter field experiment between 2016 and 2017,four treatments(bare land(BL),natural snowfall coverage(NS),5-cm-deep straw+natural snowfall coverage(SC5),and 10-cm-deep straw+natural snowfall coverage(SC10))were established to determine the effects of the different treatments on soil temperature at the soil surface and at depths of 10 cm,20 cm,and 30 cm.The environmental factors of ambient temperature,ambient humidity,water vapor pressure,10-min wind speed,total radiation,net radiation,and long wave radiation were obtained from the weather station in the study area.Through correlation,multiple regression,and stepwise regression analysis,models for dynamic simulation of the tillage-layer soil temperature were constructed for analyzing the relation between tillage-layer soil temperature and environmental factors.The results showed that the environmental factors were all significantly correlated with tillage-layer temperature at the 0.01 level;when the impacts of other environmental factors were excluded,the correlations decreased significantly.The dynamic simulation models for tillage-layer soil temperature under different coverage conditions were different,and the larger the coverage amount,the fewer the environmental factors that could affect the tillage-layer temperature.The coefficients of determination of the prediction results of the dynamic models for the tillage-layer soil temperature under the four treatments(BL,NS,SC5,and SC10)were 0.8385,0.7110,0.7283,and 0.6216,respectively.The prediction had a high accuracy and can accurately depict the dynamic changes of the tillage-layer soil temperature.The results provided a theoretical basis for the efficient utilization of farmland soil water and heat resources.展开更多
Given the adverse effects of current water shortages,low utilization and imbalance between the supply and demand,and other status quo problems relating to social economic development,the construction industry and agri...Given the adverse effects of current water shortages,low utilization and imbalance between the supply and demand,and other status quo problems relating to social economic development,the construction industry and agriculture,a cloud model was applied to a water resource system using five sustainable water resource utilization schemes for Kiamusze,Heilongjiang Province,as an example.This research changes the qualitative description of the concept language into a quantitative analysis of an evaluation indicator.A cloud model-based analytical method for regional sustainable water resource utilization schemes was proposed,and the sustainable grades of the water resources were calculated.The research results showed that,in addition to the natural continuation of such schemes,the development trends of four new schemes achieved the sustainable utilization of water resources,and thus,the sustainable water resource utilization was optimized.However,when the open-source,throttle,comprehensive and coordination schemes were subjected to the optimum applicability analysis,based on the limiting factors in different periods,resource availability and long-term development,decision-making regarding the best solution in different periods better ensures sustainable development in Kiamusze.The research results provide a significant theoretical basis for the formulation of scientific and reasonable sustainable water resource utilization strategies in Kiamusze.展开更多
The lining canals in seasonal frozen soil areas can be severely damaged by frost heaving.The freezing and thawing contributes to the continual change of the temperature field and moisture field beneath lining canal,wh...The lining canals in seasonal frozen soil areas can be severely damaged by frost heaving.The freezing and thawing contributes to the continual change of the temperature field and moisture field beneath lining canal,which will seriously affect the safe operation of the canal.In order to study the frost heaving damage mechanism of lining canal and to solve the associated engineering problems,the permafrost body was regarded as an elastomer,and a three-field,coupled,partial differential equation describing the temperature,moisture and deformation fields for a saturated two-dimensional canal bed was derived and established based on the Harlan model.The coupling equations were discretized using the finite element method in space and the finite difference method in time.The parameters were simplified appropriately based on compliance with the actual conditions and were simulated using finite element software.The results of a sample simulation showed that the simulated results and test results were basically consistent with variation laws,which proved the correctness of the numerical simulation theory and solution methods and the reliability of the calculation.The model can simulate the water,heat and deformation issues in the side slope of saturated canal bed soil in a seasonally frozen area and forecast freezing damage in the canals.展开更多
Single layer two-way grid shell with in-plane and out-of-plane tension members is a new type of single-layer latticed shell roofs. Compared with traditional single-layer latticed shells,this new type has a unique mesh...Single layer two-way grid shell with in-plane and out-of-plane tension members is a new type of single-layer latticed shell roofs. Compared with traditional single-layer latticed shells,this new type has a unique mesh form and excellent rigidity. In order to further understand the buckling behaviors of single layer two-way grid cylindrical shell roof with tension members,the buckling experiments have been undertaken to investigate the effect of tension members,in either out-of-plane or in-plane placement. A single layer two-way grid cylindrical shell roof with out-of-plane tension members has been tested under symmetric and asymmetric loading. The tension member placement,the introducing initial axial force to tension members and the load patterns are considered to investigate the buckling behavior. Experimental results indicate that four long out-ofplane tension members work well under symmetrical loading,but only two long out-of-plane tension members work under asymmetrical loading. It can be concluded that the PC bar members used as tension members for this study are useful in the construction of a single layer two-way grid cylindrical shell roof with structural members intersecting at small angles.展开更多
Neonicotinoid insecticides(NNIs)have been intensively used and exploited,resulting in their presence and accumulation in multiple environmental media.We herein investigated the current levels of eight major NNIs in th...Neonicotinoid insecticides(NNIs)have been intensively used and exploited,resulting in their presence and accumulation in multiple environmental media.We herein investigated the current levels of eight major NNIs in the Harbin section of the Songhua River in northeast China,providing the first systematic report on NNIs in this region.At least four NNIs in water and three in sediment were detected,with total concentrations ranging from 30.8 to 135 ng L^(-1) and from 0.61 to 14.7 ng g^(-1) dw,respectively.Larger spatial variations in surface water NNIs concentrations were observed in tributary than mainstream(p<0.05)due to the intensive human activities(e.g.,horticulture,urban landscaping,and household pet flea control)and the discharge of wastewater from many treatment plants.There was a significant positive correlation(p<0.05)between the concentrations of residual imidacloprid(IMI),clothianidin(CLO),and S4NNIs in the sediment and total organic carbon(TOC).Due to its high solubility and low octanol-water partition coefficient(Kow),the sediment-water exchange behavior shows that NNIs in sediments can re-enter into the water body.Human exposure risk was assessed using the relative potency factor(RPF),which showed that infants have the highest exposure risk(estimated daily intake(SIMIeq EDI):31.9 ng kg^(-1) bw$d^(-1)).The concentration thresholds of NNIs for aquatic organisms in the Harbin section of the Songhua River were determined using the species sensitivity distribution(SSD)approach,resulting in a value of 355 ng L^(-1) for acute hazardous concentration for 5%of species(HC5)and 165 ng L^(-1) for chronic HC5.Aquatic organisms at low trophic levels were more vulnerable to potential harm from NNIs.展开更多
The selection of optimal intensity measures(IMs)has been recommended for generating the seismic demand models with different probabilities by researchers since the seismic IMs are closely associated with earthquake ri...The selection of optimal intensity measures(IMs)has been recommended for generating the seismic demand models with different probabilities by researchers since the seismic IMs are closely associated with earthquake risks and structural safety.However,the seismic design code(mainly for aboveground structures)and dynamic analysis of underground structures conventionally employ the peak ground acceleration(PGA)as an optimal IM.In this paper,the research is to identify the optimal scalar and vector IMs in the fragility investigation of deep-buried hydraulic arched tunnels using the finite element method.A refinement process was performed to determine the optimal scalar IMs by comprehensively comparing their correlation,efficiency,practicality,proficiency,and sufficiency among the examined IMs.Furtherly,the optimum vector IMs were also developed,followed by the three different scalar IMs.Eventually,the dif-ferences between the fragility curves of the tunnel produced using the optimal scalar and vector IM were compared.The generated vector fragility surface can be used to estimate the seismic fragility of identical hydraulic tunnels in an approximative manner.展开更多
基金supported by the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(2021ZT090543)the National Natural Science Foundation of China(U20A20117)the Key-Area Research and Development Program of Guangdong Province(2020B1111380003).
文摘Land use/land cover represents the interactive and comprehensive influences between human activities and natural conditions,leading to potential conflicts among natural and human-related issues as well as among stakeholders.This study introduced economic standards for farmers.A hybrid approach(CA-ABM)of cellular automaton(CA)and an agent-based model(ABM)was developed to effectively deal with social and land-use synergic issues to examine human–environment interactions and projections of land-use conversions for a humid basin in south China.Natural attributes and socioeconomic data were used to analyze land use/land cover and its drivers of change.The major modules of the CA-ABM are initialization,migration,assets,land suitability,and land-use change decisions.Empirical estimates of the factors influencing the urban land-use conversion probability were captured using parameters based on a spatial logistic regression(SLR)model.Simultaneously,multicriteria evaluation(MCE)and Markov models were introduced to obtain empirical estimates of the factors affecting the probability of ecological land conversion.An agent-based CA-SLR-MCE-Markov(ABCSMM)land-use conversion model was proposed to explore the impacts of policies on land-use conversion.This model can reproduce observed land-use patterns and provide links for forest transition and urban expansion to land-use decisions and ecosystem services.The results demonstrated land-use simulations under multi-policy scenarios,revealing the usefulness of the model for normative research on land-use management.
基金Supported by Heilongjiang Province Technological and Scientific Research Project(12531051)
文摘Irrigation water became the limiting factor to the persistent improvement of grain production. Based on the data from Gannan County, a semiarid area in the west of Heilongjiang Province, the present situation of the development and utilization of water resources and the suitable water saving irrigation mode were analyzed by using SPA model, which was significant to the efficient and rational utilization of water resources and the improvement of agriculture productivity. The result showed that the model could be applied well to the assessment of development and utilization of water resources and the multi-project optimal selection. Through calculation, it could be found that the utilization of water resources in Gannan County was still in the primary stage, and the integration technology of the optimized water saving irrigation should be combined to support the sustainable development of agriculture in the semiarid area.
基金Supported by the Natural Science Foundation of China(51179032,51279031)
文摘The paper analyzed the seasonal variation of the concentrations of Cr, Mn, A1, N, P, As, Ba, Ca, Cu, Fe, Mg, and K in South Lake Cyohoha water using spectroscopic technique. Water samples were taken monthly at Ngenda, Karehe and Nyamabuye stations from January 2009 to December 2010. The results showed that the concentrations of aluminum, nitrogen, potassium, arsenic, phosphorous, manganese, chromium, barium and copper were high during the raining season and low during the dry season, while calcium, iron and magnesium varied independently with seasonal change. The results of conductivity and pH also confirmed the effects of seasonal change on the quality of water in the South Lake Cyohoha since the highest value of conductivity was found during the raining season, while the smallest was observed during the dry season, for pH the highest number was noticed during the dry season and the lowest during the raining season.
基金Supported by the National Key Research and Development Program of China(2016YFC040010101)。
文摘Different irrigation schemes have different effects on water consumption in rice production.However,few studies have been conducted on the water consumption processes between dry direct seeding rice and transplanting rice under different irrigation schemes.Water consumption process,water use efficiency and correlation effect of water consumption on yield under different planting models in rice production were investigated in northeast China in 2018.Seven treatments were implemented:drip irrigation dry direct seeding rice(DDSR),wet irrigation dry direct seeding rice(WDSR),flooded irrigation dry direct seeding rice(FDSR),transplanting flooded rice(TFR),controlled irrigation transplanting rice(CTR),intermittent irrigation transplanting rice(ITR)and wet irrigation transplanting rice(WTR).Among them,TFR was the control.The results showed that the peaks of the water consumption amount,intensity and its modulus coefficient of the seven treatments all appeared in the middle tillering and the jointing booting stages.The total water consumption amount(ET)and average water consumption intensity of DDSR,WDSR,FDSR and WTR were lower than those of TFR,CTR and ITR.The maximum water use efficiency of yield(WUEy)occurred in DDSR with a value of 3.8 kg·m^(-3).WUEy of DDSR,WDSR and FDSR were significantly higher than those of TFR,CTR and ITR.In the middle tillering and the heading and flowering stages,the water consumption amount of each treatment had a positive effect on yield formation,and the water consumption amount in the late tillering stage had a negative effect on yield formation.The relationship between ET and yield(Y)of dry direct seeding and transplanting planting models showed a quadratic function curve.ET of transplanting planting model had a significant positive impact on Y,and ET of dry direct seeding planting model had no impact on Y.DDSR had the least total water consumption of 199.8 mm·m^(-2),the lowest water consumption intensity of 2.0 mm·d^(-1) and the greatest water use efficiency of 3.8 kg·m^(-3),which suggested that DDSR had the most significant water saving effect.The combination of dry direct seeding planting model and drip irrigation scheme would be a good option for determining a water-saving rice planting model in northeast China.
基金Funded by the National Natural Science Foundation of China(Nos.52074245,52374416 and 52202029)the China Postdoctoral Science Foundation(No.2022M721058)。
文摘Up to 1.5wt%of Cr(Ⅲ)salts(CrCl_(3),and Cr_(2)O_(3))and Cr(Ⅵ)salts(Na_(2)CrO_(4),and CaCr_(2)O_(7))were incorporated into red mud-based geopolymers,respectively.The solidification/stabilization,compressive strength,and durability of the Cr-containing geopolymers were investigated.The experimental results indicate that the red mud-based geopolymer could effectively solidify/stabilize different types of Cr salts with solidification/stabilization rates of above 99.61%.Geopolymers are environmentally safe when the dosage of CaCr_(2)O_(7)is≤1.0wt%,or the dosage of CrCl_(3),Cr_(2)O_(3),and Na_(2)CrO_(4)is≤1.5wt%,respectively.The effects of Cr salts on the compressive strength varies with the type and content of Cr salts.The freeze-thaw cycle is more destructive to geopolymer properties than sulfate attack or acid rain erosion.The solidification/stabilization of Cr is mainly attributed to the following reasons:a)The chemical binding of Cr is related to the formation of Cr-containing hydrates(eg,magnesiochromite((Mg,Fe)(Cr,Al)_(2)O_(4)))and doping into N-A-S-H gel and C-A-S-H gel framework;b)The physical effect is related to the encapsulation by the hydration products(e g,N-A-S-H gel and C-A-S-H gel).This study provides a reference for the treatment of hazardous Cr-containing wastes by solid waste-based geopolymers.
基金National Natural Science Foundation of China under Grant No.51608488Scientific and Technological Project of Henan Province,China under Grant No.222102320006+1 种基金Zhengzhou University 2022 Annual Basic Research Foundation for Young Teachers,China under Grant No.JC22547025Postdoctoral Research Grant in Henan Province。
文摘The deterioration of the performance of offshore bridges is particularly prominent due to the complex natural environment,including the coupling effects of earthquake and seawater erosion.In particular,bridge piers are the main energy-consuming and load-bearing components,so that excellent seismic capacity of bridge piers is the key to avoiding bridge damage.Although earthquake resistant behavior of ordinary reinforced concrete bridge piers(ordinary pier)can be improved by increasing the section size and reinforcement ratio of piers,the improvement of the earthquake resistant behavior is limited.To further improve the earthquake resistant behavior of bridge piers,high-tensile reinforcement engineered cementitious composite(ECC)bridge piers are utilized and time-varying seismic fragility analysis are conducted in this study.The refined model of a bridge pier is built by OpenSees.First,the influence of ECC replacement height on pier curvature is analyzed to determine the reasonable ECC height.Then,the time-varying fragility analysis of high-tensile reinforcement ECC piers(ECC composite piers)with durability damage are evaluated considering the time-varying law of materials.Four damage states,slight damage,moderate damage,extensive damage and complete collapse,are utilized in the study.These fragility curves indicate the durability damage can debase the earthquake resistant behavior of piers continually,the exceedance probability of the same state of destruction increases with the increase of peak ground acceleration(PGA)and service time of pier.The results also indicate that the corrosion level of chloride ion to pier is small during the early service period,and the bridge pier vulnerable curve is similar to that of the new bridge pier.As the level of chlorine ion corrosion deepens,transcendental probability is increased.Compared with the ordinary pier,the exceedance probability in each limit state of ECC composite piers is significantly reduced.The proposed ECC composite pies leads to better realistic time-varying earthquake resistant behavior.
基金This research was supported by the National Natural Science Foundation of China(Grant nos.41876213 and 41722605)the National Key R&D Program of China(Grant nos.2017YFE0111400 and 2016YFC14003).
文摘Using six ice-tethered buoys deployed in 2012,we analyzed sea ice motion in the central Arctic Ocean and Fram Strait.The two-hourly buoy-derived ice velocities had a magnitude range of 0.010.80 m s 1,although ice velocities within the Arctic Basin were generally less than 0.4 m s 1.Complex Fourier transformation showed that the amplitudes of the sea ice velocities had a non-symmetric inertial oscillation.These inertial oscillations were characterized by a strong peak at a frequency of approximately 2 cycle d 1 on the Fourier velocity spectrum.Wind was a main driving force for ice motion,characterized by a linear relationship between ice velocity and 10-m wind speed.Typically,the ice velocity was about 1.4%of the 10-m wind speed.Our analysis of ice velocity and skin temperature showed that ice velocity increased by nearly 2%with each 10℃increase in skin temperature.This was likely related to weakened ice strength under increasing temperature.The ice-wind turning angle was also correlated with 10-m wind speed and skin temperature.When the wind speed was less than 12 m s 1 or skin temperature was less than 30℃,the ice-wind turning angle decreased with either increasing wind speed or skin temperature.Clearly,sea ice drift in the central Arctic Ocean and Fram Strait is dependent upon seasonal changes in both temperature and wind speed.
基金supported by the financial support from the Key R&D Projects of the Ministry of Transport(2018-MS5-136)Henan Province Transportation Science and Technology Plan Project(2018J2,2019J-2-10,2020J-2-7).
文摘In this paper,a notched three-point bending test is used to study the fracture performance of the short basalt fiber bundle reinforced concrete(SBFBRC).To compare and analyze the enhancement effect of different diameters and different content of basalt fiber bundles on the fracture performance of concrete,some groups are set up,and the P-CMOD curves of each group of specimens are measured,and the fracture toughness and fracture energy of each control group are calculated.The fracture toughness and fracture energy are two important fracture performance parameters to study the effect and law of the new basalt fiber bundles on the fracture performance of concrete.The research results show that the diameter and content of the new basalt fiber bundles have a certain effect on the fracture performance of concrete.With the increase of the content of basalt fiber bundles,the peak load,crack initiation toughness,instability toughness and fracture energy of SBFBRC are greatly improved compared with the benchmark group.When the fiber bundle diameter is 0.2 mm,the peak load increases by 69.5%compared with the reference group.The instability toughness reaches its maximum value at 0.2 mm diameter,which is 59.7%higher than the benchmark.
基金National Natural Science Foundation of China(Grant No.51708228)GD Midea Environment Appliances MFG.Co.,Ltd.
文摘Air movement dries surfaces by increasing evaporation and convection,which may prevent mould growth.Cladosporium sp.is used as the test organism(dominant fungi in the envelope of rural houses in hot summer and warm winter areas),and the effect of fans on inhibiting mould growth on building materials is investigated.Surface mould growth on materials was simulated and compared after rain leakage and surface condensation,and spore germination was studied in high humidity,with or without airflow.The results are as follows:(1)Airflow has an evident inhibitory effect on mould growth on wet building materials.This observation was linked to the availability of moisture content in the building materials.(2)Airflow can slow the appearance of visual mould on the material surface.Mould did not appear on the gypsum surface due to the airflow,and mould growth on a wood surface was delayed for about two days.(3)Periodically,spore eluates were examined by electron microscopy to determine the stage of spore germination,and it was found that airflow delayed mould spore germination for about 2-3 days.
基金National Natural Science Foundation of China(51479032,51579044)Yangtze River Scholars in Universities of Heilongjiang Province and Water Conservancy Science and Technology Project of Heilongjiang Province(201318,201503)The Outstanding Youth Fund of Heilongjiang Province(JC201402).
文摘For optimizing the water-use structure and increasing plantation benefit of unit water consumption,a multi-objective model for water resources utilization was established based on fractional programming(FP).Meanwhile,considering the stochasticity of water availability in the study area,the impact of the risk factor(λ)from a quantitative and qualitative perspective was analyzed.The chance-constrained programming(CCP)and conditional value-at-risk(CVaR)models were introduced into five important major grain production areas in Sanjiang Plain,and the crop planting structure under this condition was optimized.The results showed that,after optimization,overall benefit of cultivation increased from 42.07 billion Yuan to 42.47 billion Yuan,water consumption decreased from 15.90 billion m3 to 11.95 billion m3,the plantation benefit of unit water consumption increased from 2.65 Yuan/m3 to 3.55 Yuan/m3.Furthermore,the index of water consumption,benefit of cultivation and plantation benefit of unit water consumption showed an increasing trend with the increase of violation likelihood.However,through the quantification ofλfrom an economic perspective,the increasing ofλcould not enhance plantation benefit of unit water consumption significantly.
基金This work was supported by Natural Science Foundation of Heilongjiang Province of China(No.E2016004)National Natural Science Foundation of China(No.51679040)+1 种基金University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province of China(No.UNPYSCT-2017022)Postdoctoral Scientific Research Developmental Fund of Heilongjiang Province of China(No.LBH-Q17022).
文摘Coordinated and orderly water and land resource system is vital to ensure the economic and social development of a region.Grain production in Heilongjiang Province has increased consecutively every year since 2003,and numerous water and land resource-related problems have become increasingly prominent and have had significant adverse effects on social and economic development and stability in the region.In this study,Heilongjiang Province and its 13 prefecture-level cities were selected as the study area,and the degrees of coordination of the social,economic and ecological subsystems were evaluated using periphery theory and the theory of synergetics.To ensure that the assessment was objective and accurate,weights were calculated using the projection pursuit technique,and similarity degrees were calculated using a modified(by introducing the chi-square distance)order of preference by similarity to ideal solution(TOPSIS)technique.Moreover,to reflect the variations in the overall degree of coordination in Heilongjiang Province,the risk level of the coordination of the water and land resource system was predicted through the year 2020 using a dynamic neural network.This study provides a reference for establishing effective and balanced coordination between society and water and land resources.
基金the National Natural Science Foundation of China(No.41401550)the Humanity and Social Science Youth Foundation of Ministry of Education of China(No.14YJCZH017)+4 种基金the Heilongjiang Post-Doctoral Financial Assistance of China(No.LBH-Z13029)the Scientific Research Fund of Heilongjiang Provincial Education Department(No.12541123)the Young Talents Project of Northeast Agricultural University(No.14QC49)the Natural Science Foundation of Heilongjiang Province(No.QC2016054)the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(UNPYSCT-2016001).
文摘In order to investigate the transfer and migration behavior of polycyclic aromatic hydrocarbons(PAHs)in soil with long-term wastewater irrigation,Groundwater Ubiquity Score(GUS)and fugacity method were respectively used to assess the potential entry into the groundwater and transfer capacity of PAHs.The results of assessment using GUS show that there is significant correlation between the GUS and organic carbon sorption coefficient(KOC)for PAHs and a simple assessment method with KOC was referred to evaluate contamination of groundwater.Applying fugacity method,evaluation results of transfer and migration of PAHs in soil suggest that the PAHs accumulation in the soil through long-term wastewater irrigation could be re-volatilized as secondary emission sources to atmosphere for the Low Molecular Weight(LMW)PAHs,in contrast to High Molecular Weight(HMW)PAHs for which the soil remains a sink that could absorb more PAHs.The net volatilisation flux was 0.39 g/d in upland and 0.32 g/d in paddy for LMW Nap(Naphthalene),and 0.97×10^(-3)g/d in upland and 0.37×10^(-3)g/d in paddy for LMW Phe(Phenanthrene).The net deposition was 0.72×10^(-4)g/d in upland and 0.10×10^(-3)g/d in paddy for HMW Fla(Fluoranthene),and 0.22×10^(-4)g/d in upland and 0.20×10^(-4)g/d in paddy for HMW Bap(Benzo[a]pyrene).Sensitivities of the model estimates to input parameters were tested,and the sensitivity coefficient was defined for the test.The most influential parameters were the volumes of the air,water,and organic carbon fractions in soil and the thickness of the soil.
基金the financial support by Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(No.Z019005)the Longjiang Scholars for young scientist。
文摘Nowadays,iron ions as a ubiquitous heavy metal pollutant are gradually concerned and the convenient and quick removal of excessive iron ions in groundwater has become a major challenge for the safety of drinking water.In this study,boron-doped biochar(B-BC)was successfully prepared at various preparation conditions with the addition of boric acid.The as-prepared material has a more developed pore structure and a larger specific surface area(up to 897.97 m2/g).A series of characterization results shows that boric acid effectively activates biochar,and boron atoms are successfully doped on biochar.Compared with the ratio of raw materials,the pyrolysis temperature has a greater influence on the amount of boron doping.Based on Langmuir model,the maximum adsorption capacity of 800 B-BC1:2 at25℃,40℃,55℃ are 50.02 mg/g,95.09 mg/g,132.78 mg/g,respectively.Pseudo-second-order kinetic model can better describe the adsorption process,the adsorption process is mainly chemical adsorption.Chemical complexation,ions exchange,and co-precipitation may be the main mechanisms for Fe2+removal.
基金This work was supported by the National Key R&D Program of China(No:2017YFC0406004)the National Natural Science Foundation of China(No:51109036,51179032)+5 种基金the Natural Science Foundation of Heilongjiang Province of China(No:E2015024)the Research Fund for the Doctoral Program of Higher Education of China(No:20112325120009)the Foundation for Reserve Academic Leader in Province Lead Team of Heilongjiang Province of China(No:500001)the Research Foundation for Postdoctors of Heilongjiang Province of China(No:LBH-Q12147)the Projects for Science and Technology Development of Water Conservancy Bureau in Heilongjiang Province of China(No:201402,No:201404,No:201501)the Academic Backbones Foundation of Northeast Agricultural University(No.16XG11).
文摘To determine the influence of agricultural meteorological disasters on agriculture in Heilongjiang Province,the disaster areas associated with different types of disasters and their variation characteristics were analyzed based on the statistical data of agricultural disasters from 1983 to 2013 in Heilongjiang Province,China.The moving average and the Mann-Kendall test were applied to identify the variation trends of drought,flooding,hailstorms and freezing(based on the disaster ratio and the disaster intensity index).Then,the Morlet wavelet analysis method was used to identify the periodicity of these four kinds of agricultural meteorological disasters.Finally,a fuzzy comprehensive evaluation method was adopted to analyze the degrees of agricultural loss induced by these disasters.The following results were obtained:1)The disaster ratio and disaster intensity index for drought exhibited increasing trends;the disaster ratio and disaster intensity index for flooding exhibited decreasing trends;for hailstorms,the disaster ratio exhibited no obvious trend of change,whereas the disaster intensity index exhibited an increasing trend;and for freezing,the disaster ratio also exhibited no obvious trend of change,whereas the disaster intensity index exhibited a decreasing trend.2)Mutation points were observed in the disaster ratio series for drought,flooding and hailstorms,whereas no mutation point was evident in the disaster ratio series for freezing.3)Multiple time-scale characteristics were observed in the disaster ratio series for all four types of agricultural meteorological disasters.Furthermore,the disaster ratio series for the different types of disasters had different main periodicities.4)From the perspective of the degree of agricultural loss induced by each type of disaster,drought was identified as the most severe type of agricultural meteorological disaster,followed by flooding,freezing,and hailstorms.The degree of agricultural loss caused by each type of disaster was different during different periods.Finally,based on the results,several strategies were identified for mitigating the effect of agricultural meteorological disasters in Heilongjiang Province.
基金supported by the National Natural Science Foundation of China(51679039)the Outstanding Youth Fund of Heilongjiang Province(JC201402).
文摘Based on a winter field experiment between 2016 and 2017,four treatments(bare land(BL),natural snowfall coverage(NS),5-cm-deep straw+natural snowfall coverage(SC5),and 10-cm-deep straw+natural snowfall coverage(SC10))were established to determine the effects of the different treatments on soil temperature at the soil surface and at depths of 10 cm,20 cm,and 30 cm.The environmental factors of ambient temperature,ambient humidity,water vapor pressure,10-min wind speed,total radiation,net radiation,and long wave radiation were obtained from the weather station in the study area.Through correlation,multiple regression,and stepwise regression analysis,models for dynamic simulation of the tillage-layer soil temperature were constructed for analyzing the relation between tillage-layer soil temperature and environmental factors.The results showed that the environmental factors were all significantly correlated with tillage-layer temperature at the 0.01 level;when the impacts of other environmental factors were excluded,the correlations decreased significantly.The dynamic simulation models for tillage-layer soil temperature under different coverage conditions were different,and the larger the coverage amount,the fewer the environmental factors that could affect the tillage-layer temperature.The coefficients of determination of the prediction results of the dynamic models for the tillage-layer soil temperature under the four treatments(BL,NS,SC5,and SC10)were 0.8385,0.7110,0.7283,and 0.6216,respectively.The prediction had a high accuracy and can accurately depict the dynamic changes of the tillage-layer soil temperature.The results provided a theoretical basis for the efficient utilization of farmland soil water and heat resources.
基金The Natural Science Foundation of China(51279031,51479032,51679039 and 51579044)the Heilongjiang Province Water Conservancy Science and Technology project(201318 and 201503)+1 种基金the Heilongjiang Province Outstanding Youth Fund(JC201402)the Yangtze River Scholars Support Program of Colleges and Universities in Heilongjiang Province.
文摘Given the adverse effects of current water shortages,low utilization and imbalance between the supply and demand,and other status quo problems relating to social economic development,the construction industry and agriculture,a cloud model was applied to a water resource system using five sustainable water resource utilization schemes for Kiamusze,Heilongjiang Province,as an example.This research changes the qualitative description of the concept language into a quantitative analysis of an evaluation indicator.A cloud model-based analytical method for regional sustainable water resource utilization schemes was proposed,and the sustainable grades of the water resources were calculated.The research results showed that,in addition to the natural continuation of such schemes,the development trends of four new schemes achieved the sustainable utilization of water resources,and thus,the sustainable water resource utilization was optimized.However,when the open-source,throttle,comprehensive and coordination schemes were subjected to the optimum applicability analysis,based on the limiting factors in different periods,resource availability and long-term development,decision-making regarding the best solution in different periods better ensures sustainable development in Kiamusze.The research results provide a significant theoretical basis for the formulation of scientific and reasonable sustainable water resource utilization strategies in Kiamusze.
基金the National Natural Science Foundation(51541901)Heilongjiang Province Natural Science Foundation(E201405)Heilongjiang Province Post-Graduate Foundation(LBH-Z13031).
文摘The lining canals in seasonal frozen soil areas can be severely damaged by frost heaving.The freezing and thawing contributes to the continual change of the temperature field and moisture field beneath lining canal,which will seriously affect the safe operation of the canal.In order to study the frost heaving damage mechanism of lining canal and to solve the associated engineering problems,the permafrost body was regarded as an elastomer,and a three-field,coupled,partial differential equation describing the temperature,moisture and deformation fields for a saturated two-dimensional canal bed was derived and established based on the Harlan model.The coupling equations were discretized using the finite element method in space and the finite difference method in time.The parameters were simplified appropriately based on compliance with the actual conditions and were simulated using finite element software.The results of a sample simulation showed that the simulated results and test results were basically consistent with variation laws,which proved the correctness of the numerical simulation theory and solution methods and the reliability of the calculation.The model can simulate the water,heat and deformation issues in the side slope of saturated canal bed soil in a seasonally frozen area and forecast freezing damage in the canals.
基金Sponsored by the Postdoctoral Science Foundation of China(Grant No.2015M571422)Heilongjiang Province Postdoctoral Science Foundation(Grant No.LBH-Z14095)"Young Talents"Project of Northeast Agricultural University(Grant No.14QC50)
文摘Single layer two-way grid shell with in-plane and out-of-plane tension members is a new type of single-layer latticed shell roofs. Compared with traditional single-layer latticed shells,this new type has a unique mesh form and excellent rigidity. In order to further understand the buckling behaviors of single layer two-way grid cylindrical shell roof with tension members,the buckling experiments have been undertaken to investigate the effect of tension members,in either out-of-plane or in-plane placement. A single layer two-way grid cylindrical shell roof with out-of-plane tension members has been tested under symmetric and asymmetric loading. The tension member placement,the introducing initial axial force to tension members and the load patterns are considered to investigate the buckling behavior. Experimental results indicate that four long out-ofplane tension members work well under symmetrical loading,but only two long out-of-plane tension members work under asymmetrical loading. It can be concluded that the PC bar members used as tension members for this study are useful in the construction of a single layer two-way grid cylindrical shell roof with structural members intersecting at small angles.
基金This work was supported by the National Natural Science Foundation of China(No.51779047)the Excellent Youth Science Foundation of Heilongjiang Province(YQ2019E001).
文摘Neonicotinoid insecticides(NNIs)have been intensively used and exploited,resulting in their presence and accumulation in multiple environmental media.We herein investigated the current levels of eight major NNIs in the Harbin section of the Songhua River in northeast China,providing the first systematic report on NNIs in this region.At least four NNIs in water and three in sediment were detected,with total concentrations ranging from 30.8 to 135 ng L^(-1) and from 0.61 to 14.7 ng g^(-1) dw,respectively.Larger spatial variations in surface water NNIs concentrations were observed in tributary than mainstream(p<0.05)due to the intensive human activities(e.g.,horticulture,urban landscaping,and household pet flea control)and the discharge of wastewater from many treatment plants.There was a significant positive correlation(p<0.05)between the concentrations of residual imidacloprid(IMI),clothianidin(CLO),and S4NNIs in the sediment and total organic carbon(TOC).Due to its high solubility and low octanol-water partition coefficient(Kow),the sediment-water exchange behavior shows that NNIs in sediments can re-enter into the water body.Human exposure risk was assessed using the relative potency factor(RPF),which showed that infants have the highest exposure risk(estimated daily intake(SIMIeq EDI):31.9 ng kg^(-1) bw$d^(-1)).The concentration thresholds of NNIs for aquatic organisms in the Harbin section of the Songhua River were determined using the species sensitivity distribution(SSD)approach,resulting in a value of 355 ng L^(-1) for acute hazardous concentration for 5%of species(HC5)and 165 ng L^(-1) for chronic HC5.Aquatic organisms at low trophic levels were more vulnerable to potential harm from NNIs.
基金support from the National Natural Science Foundation of China(Grant No.52209169).
文摘The selection of optimal intensity measures(IMs)has been recommended for generating the seismic demand models with different probabilities by researchers since the seismic IMs are closely associated with earthquake risks and structural safety.However,the seismic design code(mainly for aboveground structures)and dynamic analysis of underground structures conventionally employ the peak ground acceleration(PGA)as an optimal IM.In this paper,the research is to identify the optimal scalar and vector IMs in the fragility investigation of deep-buried hydraulic arched tunnels using the finite element method.A refinement process was performed to determine the optimal scalar IMs by comprehensively comparing their correlation,efficiency,practicality,proficiency,and sufficiency among the examined IMs.Furtherly,the optimum vector IMs were also developed,followed by the three different scalar IMs.Eventually,the dif-ferences between the fragility curves of the tunnel produced using the optimal scalar and vector IM were compared.The generated vector fragility surface can be used to estimate the seismic fragility of identical hydraulic tunnels in an approximative manner.
