Bioelectrochemical regulation has been proved to enhance the traditional anaerobic digestion(AD)of organic wastes.However,few investigations have explored whether it is possible to enhance the production of biomethane...Bioelectrochemical regulation has been proved to enhance the traditional anaerobic digestion(AD)of organic wastes.However,few investigations have explored whether it is possible to enhance the production of biomethane from raw corn stover(CS).A single-chamber microbial electrolysis cell(MEC)was incorporated with an AD to form a new system(MEC-AD)with aiming at more efficient bioconversion of CS to biomethane.The performance and microbiological characteristics of MEC-AD was investigated,and compared with conventional AD,which were inoculated with original inoculum(UAD)and electrically domesticated inoculum(EAD),respectively.The results showed that MEC-AD achieved the highest CH_(4)yield of 239.13 ml·g^(-1)volatile solids(VS),which was 29.28%and 12.44%higher than those of UAD and EAD,respectively.MEC-AD also achieved higher substance conversion rates of 73.24%VS,91.16%cellulose,and 77.24%hemicellulose,respectively.The community characteristics of microorganisms revealed that the relative abundance and interactions of functional microorganisms in MEC-AD were obviously different from UAD and EAD.In MEC-AD,Electroactive bacteria(Sedimentibacter)with electrotrophic methanogens(Methanosarcina and Methanosaeta)in anodic biofilms established electrotrophic methanogenesis through direct interspecies electron transfer(DIET).The process of methanotrophic methanogenesis was facilitated by the interactions between fermentative acid-producing bacteria(FABs),syntrophic organic acid oxidation bacteria(SOBs),and methylotrophic methanogens(Methyl-HMs)in MEC-AD suspensions.Efficient synergistic interactions between these functional microorganisms improved the performance of MEC-AD in converting CS to produce biomethane.The study could provide an effective means for achieving higher AD biomethane production from raw CS.展开更多
Climate change significantly affects environment,ecosystems,communities,and economies.These impacts often result in quick and gradual changes in water resources,environmental conditions,and weather patterns.A geograph...Climate change significantly affects environment,ecosystems,communities,and economies.These impacts often result in quick and gradual changes in water resources,environmental conditions,and weather patterns.A geographical study was conducted in Arizona State,USA,to examine monthly precipi-tation concentration rates over time.This analysis used a high-resolution 0.50×0.50 grid for monthly precip-itation data from 1961 to 2022,Provided by the Climatic Research Unit.The study aimed to analyze climatic changes affected the first and last five years of each decade,as well as the entire decade,during the specified period.GIS was used to meet the objectives of this study.Arizona experienced 51–568 mm,67–560 mm,63–622 mm,and 52–590 mm of rainfall in the sixth,seventh,eighth,and ninth decades of the second millennium,respectively.Both the first and second five year periods of each decade showed accept-able rainfall amounts despite fluctuations.However,rainfall decreased in the first and second decades of the third millennium.and in the first two years of the third decade.Rainfall amounts dropped to 42–472 mm,55–469 mm,and 74–498 mm,respectively,indicating a downward trend in precipitation.The central part of the state received the highest rainfall,while the eastern and western regions(spanning north to south)had significantly less.Over the decades of the third millennium,the average annual rainfall every five years was relatively low,showing a declining trend due to severe climate changes,generally ranging between 35 mm and 498 mm.The central regions consistently received more rainfall than the eastern and western outskirts.Arizona is currently experiencing a decrease in rainfall due to climate change,a situation that could deterio-rate further.This highlights the need to optimize the use of existing rainfall and explore alternative water sources.展开更多
Deep mining,characterized by high stress,elevated geothermal gradients,and significant moisture content,significantly increases the risk of Coal Spontaneous Combustion(CSC),posing a major threat to mine safety.This st...Deep mining,characterized by high stress,elevated geothermal gradients,and significant moisture content,significantly increases the risk of Coal Spontaneous Combustion(CSC),posing a major threat to mine safety.This study delves into the impact of these factors on the self-ignition properties of coal,leveraging data from four distinctmines inHeilongjiang Province,China:ShuangyashanDongrongNo.2 Mine,Hegang JundeCoal Mine,Qitaihe Longhu Coal Mine,and Jixi Ronghua No.1Mine.We have honed the theoretical framework to account for variations in gas content during CSC.Our investigation,conducted through programmed temperature rise experiments,scrutinized the generation and temperature-dependent evolution of gases,emphasizing individual indicators such as CO,O_(2),and CxHy,in addition to composite indicators like the ratio of change in CO to change in O_(2) concentration(∂C_(CO)/∂t:−∂C_(O_(2))/∂t)and the ratio of C2H4 to C_(2)H_(6).These insights have catalyzed the development of a CSC state energy level transition model and a precise method for phase-based quantification of combustion progression.Our findings furnish a scientific foundation for the formulation of early warning and prevention strategies in deep mining settings.展开更多
Coal dust explosions are severe safety accidents in coal mine production,posing significant threats to life and property.Predicting the maximum explosion pressure(Pm)of coal dust using deep learning models can effecti...Coal dust explosions are severe safety accidents in coal mine production,posing significant threats to life and property.Predicting the maximum explosion pressure(Pm)of coal dust using deep learning models can effectively assess potential risks and provide a scientific basis for preventing coal dust explosions.In this study,a 20-L explosion sphere apparatus was used to test the maximum explosion pressure of coal dust under seven different particle sizes and ten mass concentrations(Cdust),resulting in a dataset of 70 experimental groups.Through Spearman correlation analysis and random forest feature selection methods,particle size(D_(10),D_(20),D_(50))and mass concentration(Cdust)were identified as critical feature parameters from the ten initial parameters of the coal dust samples.Based on this,a hybrid Long Short-Term Memory(LSTM)network model incorporating a Multi-Head Attention Mechanism and the Sparrow Search Algorithm(SSA)was proposed to predict the maximum explosion pressure of coal dust.The results demonstrate that the SSA-LSTM-Multi-Head Attention model excels in predicting the maximum explosion pressure of coal dust.The four evaluation metrics indicate that the model achieved a coefficient of determination(R^(2)),root mean square error(RMSE),mean absolute percentage error(MAPE),and mean absolute error(MAE)of 0.9841,0.0030,0.0074,and 0.0049,respectively,in the training set.In the testing set,these values were 0.9743,0.0087,0.0108,and 0.0069,respectively.Compared to artificial neural networks(ANN),random forest(RF),support vector machines(SVM),particle swarm optimized-SVM(PSO-SVM)neural networks,and the traditional single-model LSTM,the SSA-LSTM-Multi-Head Attention model demonstrated superior generalization capability and prediction accuracy.The findings of this study not only advance the application of deep learning in coal dust explosion prediction but also provide robust technical support for the prevention and risk assessment of coal dust explosions.展开更多
Freshwater lakes globally are witnessing an escalation in the frequency and intensity of cyanobacterial harmful blooms.However,underlying factors influencing the succession or coexistence of cyanobacteria,especially f...Freshwater lakes globally are witnessing an escalation in the frequency and intensity of cyanobacterial harmful blooms.However,underlying factors influencing the succession or coexistence of cyanobacteria,especially filamentous ones,remain poorly understood.Lake Honghu,a Ramsar Wetland of International Importance with degrading aquatic ecological quality,served as a case study to elucidate the intricate relationship between environmental changes and cyanobacterial dynamics.Our analysis revealed a significant increase in the dominance of filamentous cyanobacteria,marked by high spatiotemporal variability in community structure.This dominance of filamentous diazotrophic cyanobacteria is attributed to a decrease in the ratio of dissolved inorganic nitrogen to total phosphorus and their capacity to utilize organic phosphorus in phosphorus-deficient conditions.Species-specific density variations were linked to diverse environmental factors,with total nitrogen or total phosphorus concentration remaining as a crucial factor influencing dominant cyanobacterial density fluctuations.The dominance of low-temperature-tolerant Aphanizomenon and Pseudanabaena was evident in spring and winter,whereas Dolichospermum and Cylindrospermopsis,which prefer higher temperatures,thrived in summer and autumn.Additionally,non-algal turbidity and heterogeneity can potentially alter the competitive outcome among filamentous cyanobacteria or foster coexistence under conditions of elevated temperatures and nutrient limitation.This study predicts that filamentous cyanobacteria may spread and persist in lakes spanning a wide trophic range.Current findings enhance our comprehen-sion of the dynamic responses exhibited by filamentous bloom-forming cyanobacteria in the face of environmental changes within shallow eutrophic lakes and provide valuable insights for lake managers involved in the remediation of degraded shallow lakes.展开更多
In real world applications the supply, the demand and the transportation cost per unit of the quantities in a transportation problem are hardly specified precisely because of the changing economic and environmental co...In real world applications the supply, the demand and the transportation cost per unit of the quantities in a transportation problem are hardly specified precisely because of the changing economic and environmental conditions. It is also important that the time required for transportation should be minimum. In this paper a method has been proposed for the minimization of transportation costs. Supply and transportation costs per unit of the quantities are also determined. The present study was carried out to evaluate the quality of gravel to know its suitability for aggregate (raw material for concrete and road). The samples of gravel were analyzed for petrographic, physical, mechanical and chemical properties. Samples were categorized as quartzite group and carbonate group according to ASTM standard 295. Among these, samples of quartzite group were found dominant. The petrography examination of gravels which was carried out constituted of opal, tridymite, chalcedony, crystobalite and alkali carbonates rocks. Those minerals react with alkalis in cement leading to expansion and cracking of concrete. Other components such as sulfides, sulfates, halites, iron oxides, clay minerals and anhydrites are examined, which might be present as coating and impurities. The present study indicated that all samples are suitable for concrete making and obtain the optimum solution for transporting these materials from quarries to cities with minimum cost according to Egyptian Code.展开更多
During the mining process of impact-prone coal seams,drilling pressure relief can reduce the impact propensity of the coal seam,but it also reduces the integrity and strength of the coal mass at the side of the roadwa...During the mining process of impact-prone coal seams,drilling pressure relief can reduce the impact propensity of the coal seam,but it also reduces the integrity and strength of the coal mass at the side of the roadway.Therefore,studying the mechanical properties and energy evolution rules of coal samples containing holes and filled structures has certain practical significance for achieving coordinated control of coal mine rockburst disasters and the stability of roadway surrounding rocks.To achieve this aim,seven types of burst-prone coal samples were prepared and subject to uniaxial compression experiments with the aid of a TAW-3000 electro-hydraulic servo testing machine.Besides,the stress–strain curves,acoustic emission signals,DIC strain fields and other data were collected during the experiments.Furthermore,the failure modes and energy evolutions of samples with varying drilled hole sizes and filling materials were analyzed.The results show that the indexes related to burst propensity of the drilled coal samples decline to some extent compared with those of the intact one,and the decline is positively corelated to the diameter of the drilled hole.After hole filling,the strain concentration degree around the drilled hole is lowered to a certain degree,and polyurethane filling has a more remarkable effect than cement filling.Meanwhile,hole filling can enhance the strength and deformation resistance of coal.Hole drilling can accelerate the release of accumulated elastic strain energy,turning the acoustic emission events from low-frequency and high-energy ones to high-frequency and low-energy ones,whereas hole filling can reduce the intensity of energy release.The experimental results and theoretical derivation demonstrate that hole filling promotes coal deformability and strength mainly by weakening stress concentration surrounding the drilled holes.Moreover,the fillings can achieve a better filling effect if their elastic modulus and Poisson’s ratio are closer to those of the coal body.展开更多
The nature of rock fragmentation affects the downstream mining processes like loading, hauling, and crushing the blasted rock. Therefore, it is important to evaluate rock fragmentation after blasting for choosing or d...The nature of rock fragmentation affects the downstream mining processes like loading, hauling, and crushing the blasted rock. Therefore, it is important to evaluate rock fragmentation after blasting for choosing or designing optimal strategies for these processes. However, current techniques of rock fragmentation analysis such as sieving, image-based analysis, empirical methods or artificial intelligence-based methods entail different practical challenges, for example, excessive processing time, higher costs, applicability issues in underground environments, user-biasness, accuracy issues, etc. A classification model has been developed by utilizing image analysis techniques to overcome these challenges. The model was tested on about 7500 videos of load-haul-dump (LHD) buckets with blasted material from Malmberget iron ore mine in Sweden. A Kernel-based support vector machine (SVM) method was utilized to extract frames comprising loaded LHD buckets. Then, the blasted rock in the buckets was classified into five distinct categories using the bagging k-nearest neighbor (KNN) technique. The results showed 99.8% and 89.8% accuracy for kernel-based SVM and bagging KNN classifiers, respectively. The developed framework is efficient in terms of the operation time, cost and practicability for different mines and variate amounts of rock masses.展开更多
Generation of hydroxyl radicals(·OH)is the basis of advanced oxidation process(AOP).This study investigates the catalytic activity of microporous carbonaceous structure for in-situ generation of·OH radicals....Generation of hydroxyl radicals(·OH)is the basis of advanced oxidation process(AOP).This study investigates the catalytic activity of microporous carbonaceous structure for in-situ generation of·OH radicals.Biochar(BC)was selected as a representative of carbon materials with a graphitic structure.The work aims at assessing the impact of BC structure on the activation of H2O_(2),the reinforcement of the persistent free radicals(PFRs)in BC using heavy metal complexes,and the subsequent AOP.Accordingly,three different biochars(raw,chemically-and physiochemically-activated BCs)were used for adsorption of two metal ions(nickel and lead)and the degradation of phenol(100 mg/L)through AOP.The results demonstrated four outcomes:(1)The structure of carbon material,the identity and the quantity of the metal complexes in the structure play the key roles in the AOP process.(2)the quantity of PFRs on BC significantly increased(by 200%)with structural activation and metal loading.(3)Though the Pb-loaded BC contained a larger quantity of PFRs,Ni-loaded BC exhibited a higher catalytic activity.(4)The degradation efficiency values for phenol by modified biochar in the presence of H2O_(2) was 80.3%,while the removal efficiency was found to be 17%and 22%in the two control tests,with H2O_(2)(no BC)and with BC(no H2O_(2)),respectively.Overall,the work proposes a new approach for dual applications of carbonaceous structures;adsorption of metal ions and treatment of organic contaminants through in-situ chemical oxidation(ISCO).展开更多
The Talate Pb-Zn deposit,located in the east of the NW-SE extending Devonian Kelan volcanic-sedimentary basin of the southern Altaides,occurs in the metamorphic rock series of the upper second lithological section of ...The Talate Pb-Zn deposit,located in the east of the NW-SE extending Devonian Kelan volcanic-sedimentary basin of the southern Altaides,occurs in the metamorphic rock series of the upper second lithological section of the lower Devonian lower Kangbutiebao Formation（D_1k_1~2）.The Pb-Zn orebodies are stratiform and overprinted by late sulfide—quartz veins.Two distinct mineralization periods were identified：a submarine volcanic sedimentary exhalation period and a metamorphic hydrothermal mineralization period.The metamorphic overprinting period can be further divided into two stages：an early stage characterized by bedding-parallel lentoid quartz veins developed in the chlorite schist and leptite of the ore-bearing horizon,and a late stage represented by pyritechalcopyrite-quartz veins crosscutting chlorite schist and leptite or the massive Pb-Zn ores.Fluid inclusions in the early metamorphic quartz veins are mainly CO_2-H_2O-NaCI and carbonic（CO_2±CH_4±N_2） inclusions with minor aqueous inclusions.The CO_2-H_2O-NaCl inclusions have homogenization temperatures of 294-368℃,T_（m,CO2） of-62.6 to-60.5℃,T_（h,CO2） of 7.7 to 29.6℃（homogenized into liquid）,and salinities of 5.5-7.4 wt%NaCl eqv.The carbonic inclusions have T_（m,CO2）of-60.1 to-58.5℃,and T_（h,Co2） of-4.2 to 20.6℃.Fluid inclusions in late sulfide quartz veins are also dominated by CO_2-H_2O-NaCl and CO_2±CH_4 inclusions.The CO_2-H_2O-NaCl inclusions have T_（b,tot） of142 to 360℃,T_（m,CO2）of-66.0 to-56.6℃,T_（h,CO2） of-6.0 to 29.4℃（homogenized into liquid） and salinities of 2.4-16.5 wt%NaCl eqv.The carbonic inclusions have T_（m,Co2）of-61.5 to-57.3℃,and T_（h,CO2） of-27.0to 28.7℃.The aqueous inclusions（L-V） have T_（m,ice） of-9.8 to-1.3℃ and T_（h,tot） of 205 to 412℃.The P-T trapping conditions of CO_2-rich fluid inclusions（100-370 MPa,250-368℃） are comparable with the late- to post-regional metamorphism conditions.The CO_2-rich fluids,possibly derived from regional metamorphism,were involved in the reworking and metal enrichment of the primary ores.Based on these results,the Talate Pb-Zn deposit is classified as a VMS deposit modified by metamorphic fluids.The massive Pb-Zn ores with banded and breccia structures were developed in the early period of submarine volcanic sedimentary exhalation associated with an extensional subduction-related back-arc basin,and the quartz veins bearing polymetallic sulfides were formed in the late period of metamorphic hydrothermal superimposition related to the Permian-Triassic continental collision.展开更多
The diesel particulate matter(DPM) emission from diesel powered equipment in underground mines can cause health hazards including cancer to the miners. The understanding of the DPM propagation pattern under realistic ...The diesel particulate matter(DPM) emission from diesel powered equipment in underground mines can cause health hazards including cancer to the miners. The understanding of the DPM propagation pattern under realistic mining condition is required for selecting proper DPM control strategies and to improve working practices in underground mines. In this paper, three dimensional simulations of DPM emission from the exhaust tail pipe of a load-haul-dump(LHD) vehicle and its subsequent distribution inside an isolated zone in the typical underground mine are carried out using two different solution models available in Ansys Fluent. The incoming fresh air into the isolated zone is treated as a continuous phase and DPM is treated either as a continuous phase(gas) or as a secondary discrete phase(particle). Species transport model is used when DPM is treated as gas and discrete phase model is used when DPM is assumed to behave like a particle. The distributions of DPM concentration inside the isolated zone obtained from each method are presented and compared. From the comparison results, an accurate and economical solution technique for DPM evaluation can be selected.展开更多
Diesel particulate matter(DPM) is considered carcinogenic after prolonged exposure. This paper used computational fluid dynamics(CFD) method to study the effect of four auxiliary ventilation systems on DPM distributio...Diesel particulate matter(DPM) is considered carcinogenic after prolonged exposure. This paper used computational fluid dynamics(CFD) method to study the effect of four auxiliary ventilation systems on DPM distribution in a dead-end entry with loading operation. The auxiliary ventilation systems considered include: blower fan and tubing; exhaust fan and tubing, jet fan, and push–pull system. A species transport model with buoyancy effect was used to examine the DPM dispersion pattern with unsteady state analysis. During the 200 s of the loading operation, high DPM levels were identified in the face and dead-end entry regions. This study can be used for mining engineer as guidance to design and setup of local ventilation. It can also be used for selection of DPM control strategies and DPM annual training for underground miners.展开更多
The effects of substrate mingling ratio(SMR)(1:1,1:2,1:3,3:1,and 2:1)and organic loading rate(OLR)(50-90 g total solids per liter per day)on anaerobic co-digestion performance and microbial characteristics were invest...The effects of substrate mingling ratio(SMR)(1:1,1:2,1:3,3:1,and 2:1)and organic loading rate(OLR)(50-90 g total solids per liter per day)on anaerobic co-digestion performance and microbial characteristics were investigated for pig manure(PM)and pretreated/untreated corn stover in batch and semicontinuous anaerobic digestion(AD)system.The results showed that SMR and pretreatment affected co-digestion performance.The maximum cumulative methane yield of 428.5 ml·g^(-1)(based on volatile solids(VS))was obtained for PCP13,which was 35.7%and 40.0%higher than that of CSU and PM.In the first 5 days,the maximum methane yield improvement rate was 378.1%for PCP13.The daily methane yield per gram VS of PCP13 was 11.4%-18.5%higher than that of PC_(U)13.Clostridium_sensu_stricto_1,DMER64,and Bacteroides and Methanosaeta,Methanobacterium,and Methanospirillum had higher relative abundance at the genus level.Therefore,SMR and OLR are important factor affecting the AD process,and OLR can affect methane production through volatile fatty acids.展开更多
Chitosan-stavudine （d4T） conjugate with a succinic spacer was synthesized via carbodiimide coupling reaction and structurally characterized. In order to nanosize it for improving its therapeutic properties, the chit...Chitosan-stavudine （d4T） conjugate with a succinic spacer was synthesized via carbodiimide coupling reaction and structurally characterized. In order to nanosize it for improving its therapeutic properties, the chitosan-5＇-O-succinyl-d4T conjugate was crosslinked with sodium tripolyphosphate （TPP） to obtain the chitosan-d4T conjugate nano-prodrug. The morphologies of chitosan-d4T conjugate nanoparticles were observed by transmission electron microscopy （TEM）, and their zeta potential, particle size, and polydispersity （size distribution） were measured by the dynamic light scattering （DLS） techniques. In vitro drug release studies at pH 1.1 and pH 7.4 indicate that the crosslinked chitosan-d4T conjugate nano-prodrug can prevent the coupled d4T from leaking out before entering the target viral reservoirs and provide a mild sustained release without the burst release. The results reveal that constructing conjugated chitosan nano-prodrugs may be a promising approach for improving the therapy efficacy of drugs in antiviral treatment.展开更多
Subsurface geothermal energy storage has greater potential than other energy storage strategies in terms of capacity scale and time duration.Carbon dioxide(CO_(2))is regarded as a potential medium for energy storage d...Subsurface geothermal energy storage has greater potential than other energy storage strategies in terms of capacity scale and time duration.Carbon dioxide(CO_(2))is regarded as a potential medium for energy storage due to its superior thermal properties.Moreover,the use of CO_(2)plumes for geothermal energy storage mitigates the greenhouse effect by storing CO_(2)in geological bodies.In this work,an integrated framework is proposed for synergistic geothermal energy storage and CO_(2)sequestration and utilization.Within this framework,CO_(2)is first injected into geothermal layers for energy accumulation.The resultant high-energy CO_(2)is then introduced into a target oil reservoir for CO_(2)utilization and geothermal energy storage.As a result,CO_(2)is sequestrated in the geological oil reservoir body.The results show that,as high-energy CO_(2)is injected,the average temperature of the whole target reservoir is greatly increased.With the assistance of geothermal energy,the geological utilization efficiency of CO_(2)is higher,resulting in a 10.1%increase in oil displacement efficiency.According to a storage-potential assessment of the simulated CO_(2)site,110 years after the CO_(2)injection,the utilization efficiency of the geological body will be as high as 91.2%,and the final injection quantity of the CO_(2)in the site will be as high as 9.529×10^(8)t.After 1000 years sequestration,the supercritical phase dominates in CO_(2)sequestration,followed by the liquid phase and then the mineralized phase.In addition,CO_(2)sequestration accounting for dissolution trapping increases significantly due to the presence of residual oil.More importantly,CO_(2)exhibits excellent performance in storing geothermal energy on a large scale;for example,the total energy stored in the studied geological body can provide the yearly energy supply for over 3.5×10^(7) normal households.Application of this integrated approach holds great significance for large-scale geothermal energy storage and the achievement of carbon neutrality.展开更多
For many years planning and management of water resources involved modeling and simulation of temporally sequenced and stochastic hydrologic events. Rainfall process is one of such hydrologic events which calls for ti...For many years planning and management of water resources involved modeling and simulation of temporally sequenced and stochastic hydrologic events. Rainfall process is one of such hydrologic events which calls for time series analysis to better understand interesting features contained in it. Many statistics-based methods are available to simulate and predict such a kind of time series. Autoregressive (AR), moving average (MA), autoregressive moving average (ARMA) and autoregressive integrated moving average (ARIMA) models are among those methods. In this study a search was conducted to identify and examine a capable stochastic model for annual rainfall series (over the period 1954-2015) of Debre Markos town, Ethiopia. For the historical series, normality and stationarity tests were conducted to check if the time series was from a normally distributed and stationary process. Shapiro-Wilk (SW), Anderson-Darling (AD) and Kolmogorov-Smirnov (KS) tests were among the normality tests conducted whereas, Augmented Dickey-Fuller (ADF), Phillips-Perron (PP) and Kwiatkowski-Phillips-Schmidt-Shin (KPSS) tests were among the stationarity tests. Based on the test results, logarithmic transformation and first order differencing were performed to bring the original series to a normal and stationary series. Results of model fitting showed that three models namely, AR (2), MA (1) and ARMA (2,1) were capable in describing the annual rainfall series. A diagnostic check was performed on model residuals and ARMA (2,1) was found to be the best model among the candidates. Furthermore, three information criteria: Akaike Information Criterion (AIC), the corrected Akaike Information Criterion (AICc) and Bayesian Information Criterion (BIC) were used to select the best model. In this regard, too, the least information discrepancy between the underlying process and the fitted model was obtained from ARMA (2,1) model. Hence, this model was considered as a better representative of the annual rainfall values and was used to predict five years ahead values. The mean absolute percentage error (MAPE) of the prediction was found to be less than 10%. Thus, ARMA (2,1) model could be used for forecasting and simulation of annual rainfall for planning, management and design of water resources systems in Debre Markos town.展开更多
Diesel particulate matter(DPM) is a by-product from operating diesel engines. Since diesel powers are one of the major sources of energy for mobile underground mining equipment, the adverse health effects of DPM are o...Diesel particulate matter(DPM) is a by-product from operating diesel engines. Since diesel powers are one of the major sources of energy for mobile underground mining equipment, the adverse health effects of DPM are of a great concern. This paper used computational fluid dynamics(CFD) method to study the effect of entry inclination on DPM plume distribution in a dead end entry. An upward mining face and a downward mining face were built with a truck and a loader in loading operation close to the face area. A species transport model with incorporated buoyancy effect was used to examine the DPM dispersion pattern for the above steady-state scenarios. High DPM and temperature regions were identified for the two different faces. The model was used to assess the role of auxiliary ventilation in reducing DPM exposures of underground miners working in those entries. In this study, it is suggested to provide local ventilation at least three times of the diesel exhaust rate to be able to lower the average DPM level for the mining upward face. The requirement for local ventilation is much less for the mining downward face. This can provide guidelines for good working practices and selection of diesel emission reduction technologies underground.展开更多
Relative radiometric normalization (RRN) minimizes radiometric differences among images caused by inconsistencies of acquisition conditions rather than changes in surface. Scale invariant feature transform (SIFT) has ...Relative radiometric normalization (RRN) minimizes radiometric differences among images caused by inconsistencies of acquisition conditions rather than changes in surface. Scale invariant feature transform (SIFT) has the ability to automatically extract control points (CPs) and is commonly used for remote sensing images. However, its results are mostly inaccurate and sometimes contain incorrect matching caused by generating a small number of false CP pairs. These CP pairs have high false alarm matching. This paper presents a modified method to improve the performance of SIFT CPs matching by applying sum of absolute difference (SAD) in a different manner for the new optical satellite generation called near-equatorial orbit satellite and multi-sensor images. The proposed method, which has a significantly high rate of correct matches, improves CP matching. The data in this study were obtained from the RazakSAT satellite a new near equatorial satellite system. The proposed method involves six steps: 1) data reduction, 2) applying the SIFT to automatically extract CPs, 3) refining CPs matching by using SAD algorithm with empirical threshold, and 4) calculation of true CPs intensity values over all image’ bands, 5) preforming a linear regression model between the intensity values of CPs locate in reverence and sensed image’ bands, 6) Relative radiometric normalization conducting using regression transformation functions. Different thresholds have experimentally tested and used in conducting this study (50 and 70), by followed the proposed method, and it removed the false extracted SIFT CPs to be from 775, 1125, 883, 804, 883 and 681 false pairs to 342, 424, 547, 706, 547, and 469 corrected and matched pairs, respectively.展开更多
One of the major limitations of using Interferometric Synthetic Aperture Radar(InSAR)in time series analysis is the low-phase coherence associated with rough terrain and vegetated areas,which results in limited spatia...One of the major limitations of using Interferometric Synthetic Aperture Radar(InSAR)in time series analysis is the low-phase coherence associated with rough terrain and vegetated areas,which results in limited spatial coverage in such regions.Permanent scatterers technique was introduced to overcome this limitation using time-series analysis.However,identifying major scatterers within a pixel requires the single-looked pixels oversampling which can be a demanding process especially with large interferometric stacks and vast study areas.Therefore,using multilooked temporal coherent pixels was proposed to increase processing efficiency and coverage by utilizing distributed targets,but this technique may exclude pixels with reliable phase returns because of their temporal varying neighboring pixels.In this paper,we propose a technique to identify multilooked temporal stable pixels with reliable phase returns independent of their neighboring pixels.We conduct a simulation analysis to relate the spatial coherence of a pixel with its expected temporal correlation in the time series analysis module.We found that a liberal temporal correlation threshold of 0.53 in multilooked pixels stack is equivalent to a spatial coherence threshold of 0.2 when using number of looks of 9,which is considered acceptable in temporal coherent pixels,in terms of phase standard deviation.Applying these findings to study the 2011 Tohoku earthquake in the northeastern part of Japan resulted in increasing the number of usable pixels and spatial coverage index by nearly 50.4%and 36.8%,respectively,compared to the temporal coherent pixels.Furthermore,we propose an approach to integrate GPS observations with InSAR time series analysis,which resulted in deformation maps of the megathrust 2011 Tohoku earthquake with mean RMSE of 11.4 mm and a correlation of 98%in comparison to GPS observations.展开更多
The water repellence and mechanical properties of the gelatin/Ce（Ⅲ） fiber（GCe fiber） were improved by heat treatment,which was an easy and non-toxic method.The microscopic morphology,mechanical properties,antibac...The water repellence and mechanical properties of the gelatin/Ce（Ⅲ） fiber（GCe fiber） were improved by heat treatment,which was an easy and non-toxic method.The microscopic morphology,mechanical properties,antibacterial activity,and cell culture of the GCe fibers by heat treatment（HGCe fiber） were investigated.It was found that the water repellence and mechanical properties of the HGCe fibers increased significantly along with temperature increase.SEM observation showed that HGCe fibers had a fairly smooth surface and a compact structure.Detailed characterization revealed that the HGCe fibers exhibited similar antibacterial activity with the GCe fibers against Staphylococcus aureus.In addition,the results of cell culture by morphological assessment and methylthiazolyl tetrazolium assay（MTT assay） indicated the good biocompatibility of GCe fibers.Therefore,the HGCe fibers could be a promising candidate biomaterial for biomedicine applications.展开更多
基金supports from the Fundamental Research Funds for the Central Universities(NO.JD2402).
文摘Bioelectrochemical regulation has been proved to enhance the traditional anaerobic digestion(AD)of organic wastes.However,few investigations have explored whether it is possible to enhance the production of biomethane from raw corn stover(CS).A single-chamber microbial electrolysis cell(MEC)was incorporated with an AD to form a new system(MEC-AD)with aiming at more efficient bioconversion of CS to biomethane.The performance and microbiological characteristics of MEC-AD was investigated,and compared with conventional AD,which were inoculated with original inoculum(UAD)and electrically domesticated inoculum(EAD),respectively.The results showed that MEC-AD achieved the highest CH_(4)yield of 239.13 ml·g^(-1)volatile solids(VS),which was 29.28%and 12.44%higher than those of UAD and EAD,respectively.MEC-AD also achieved higher substance conversion rates of 73.24%VS,91.16%cellulose,and 77.24%hemicellulose,respectively.The community characteristics of microorganisms revealed that the relative abundance and interactions of functional microorganisms in MEC-AD were obviously different from UAD and EAD.In MEC-AD,Electroactive bacteria(Sedimentibacter)with electrotrophic methanogens(Methanosarcina and Methanosaeta)in anodic biofilms established electrotrophic methanogenesis through direct interspecies electron transfer(DIET).The process of methanotrophic methanogenesis was facilitated by the interactions between fermentative acid-producing bacteria(FABs),syntrophic organic acid oxidation bacteria(SOBs),and methylotrophic methanogens(Methyl-HMs)in MEC-AD suspensions.Efficient synergistic interactions between these functional microorganisms improved the performance of MEC-AD in converting CS to produce biomethane.The study could provide an effective means for achieving higher AD biomethane production from raw CS.
文摘Climate change significantly affects environment,ecosystems,communities,and economies.These impacts often result in quick and gradual changes in water resources,environmental conditions,and weather patterns.A geographical study was conducted in Arizona State,USA,to examine monthly precipi-tation concentration rates over time.This analysis used a high-resolution 0.50×0.50 grid for monthly precip-itation data from 1961 to 2022,Provided by the Climatic Research Unit.The study aimed to analyze climatic changes affected the first and last five years of each decade,as well as the entire decade,during the specified period.GIS was used to meet the objectives of this study.Arizona experienced 51–568 mm,67–560 mm,63–622 mm,and 52–590 mm of rainfall in the sixth,seventh,eighth,and ninth decades of the second millennium,respectively.Both the first and second five year periods of each decade showed accept-able rainfall amounts despite fluctuations.However,rainfall decreased in the first and second decades of the third millennium.and in the first two years of the third decade.Rainfall amounts dropped to 42–472 mm,55–469 mm,and 74–498 mm,respectively,indicating a downward trend in precipitation.The central part of the state received the highest rainfall,while the eastern and western regions(spanning north to south)had significantly less.Over the decades of the third millennium,the average annual rainfall every five years was relatively low,showing a declining trend due to severe climate changes,generally ranging between 35 mm and 498 mm.The central regions consistently received more rainfall than the eastern and western outskirts.Arizona is currently experiencing a decrease in rainfall due to climate change,a situation that could deterio-rate further.This highlights the need to optimize the use of existing rainfall and explore alternative water sources.
基金This paper is supported by“Unveiling the List and Leading the Way”Science and Technology Research Project from Heilongjiang Province(2021ZXJ02A03)Major Science and Technology Support Action Plan for the“Millions”Project in Heilongjiang Province(2020ZX04A01)the Natural Science Foundation of Heilongjiang Province(LH2024E112).
文摘Deep mining,characterized by high stress,elevated geothermal gradients,and significant moisture content,significantly increases the risk of Coal Spontaneous Combustion(CSC),posing a major threat to mine safety.This study delves into the impact of these factors on the self-ignition properties of coal,leveraging data from four distinctmines inHeilongjiang Province,China:ShuangyashanDongrongNo.2 Mine,Hegang JundeCoal Mine,Qitaihe Longhu Coal Mine,and Jixi Ronghua No.1Mine.We have honed the theoretical framework to account for variations in gas content during CSC.Our investigation,conducted through programmed temperature rise experiments,scrutinized the generation and temperature-dependent evolution of gases,emphasizing individual indicators such as CO,O_(2),and CxHy,in addition to composite indicators like the ratio of change in CO to change in O_(2) concentration(∂C_(CO)/∂t:−∂C_(O_(2))/∂t)and the ratio of C2H4 to C_(2)H_(6).These insights have catalyzed the development of a CSC state energy level transition model and a precise method for phase-based quantification of combustion progression.Our findings furnish a scientific foundation for the formulation of early warning and prevention strategies in deep mining settings.
基金funded by the Research on Intelligent Mining Geological Model and Ventilation Model for Extremely Thin Coal Seam in Heilongjiang Province,China(2021ZXJ02A03)the Demonstration of Intelligent Mining for Comprehensive Mining Face in Extremely Thin Coal Seam in Heilongjiang Province,China(2021ZXJ02A04)the Natural Science Foundation of Heilongjiang Province,China(LH2024E112).
文摘Coal dust explosions are severe safety accidents in coal mine production,posing significant threats to life and property.Predicting the maximum explosion pressure(Pm)of coal dust using deep learning models can effectively assess potential risks and provide a scientific basis for preventing coal dust explosions.In this study,a 20-L explosion sphere apparatus was used to test the maximum explosion pressure of coal dust under seven different particle sizes and ten mass concentrations(Cdust),resulting in a dataset of 70 experimental groups.Through Spearman correlation analysis and random forest feature selection methods,particle size(D_(10),D_(20),D_(50))and mass concentration(Cdust)were identified as critical feature parameters from the ten initial parameters of the coal dust samples.Based on this,a hybrid Long Short-Term Memory(LSTM)network model incorporating a Multi-Head Attention Mechanism and the Sparrow Search Algorithm(SSA)was proposed to predict the maximum explosion pressure of coal dust.The results demonstrate that the SSA-LSTM-Multi-Head Attention model excels in predicting the maximum explosion pressure of coal dust.The four evaluation metrics indicate that the model achieved a coefficient of determination(R^(2)),root mean square error(RMSE),mean absolute percentage error(MAPE),and mean absolute error(MAE)of 0.9841,0.0030,0.0074,and 0.0049,respectively,in the training set.In the testing set,these values were 0.9743,0.0087,0.0108,and 0.0069,respectively.Compared to artificial neural networks(ANN),random forest(RF),support vector machines(SVM),particle swarm optimized-SVM(PSO-SVM)neural networks,and the traditional single-model LSTM,the SSA-LSTM-Multi-Head Attention model demonstrated superior generalization capability and prediction accuracy.The findings of this study not only advance the application of deep learning in coal dust explosion prediction but also provide robust technical support for the prevention and risk assessment of coal dust explosions.
基金supported by the National Key Research and Development Program of China(No.2018YFD0900701)the National Natural Science Foundation of China(No.42177246)+2 种基金Additional support was provided by Yunnan Province-Kunming City Major Science and Technology Project(No.202202AH210006)the convenience provided by workstation of academician Liu Yongding in Kunming(No.YSZJGZZ-2020018)The Natural Science Foundation of Hunan Province(No.2022JJ30691)also supported this research.
文摘Freshwater lakes globally are witnessing an escalation in the frequency and intensity of cyanobacterial harmful blooms.However,underlying factors influencing the succession or coexistence of cyanobacteria,especially filamentous ones,remain poorly understood.Lake Honghu,a Ramsar Wetland of International Importance with degrading aquatic ecological quality,served as a case study to elucidate the intricate relationship between environmental changes and cyanobacterial dynamics.Our analysis revealed a significant increase in the dominance of filamentous cyanobacteria,marked by high spatiotemporal variability in community structure.This dominance of filamentous diazotrophic cyanobacteria is attributed to a decrease in the ratio of dissolved inorganic nitrogen to total phosphorus and their capacity to utilize organic phosphorus in phosphorus-deficient conditions.Species-specific density variations were linked to diverse environmental factors,with total nitrogen or total phosphorus concentration remaining as a crucial factor influencing dominant cyanobacterial density fluctuations.The dominance of low-temperature-tolerant Aphanizomenon and Pseudanabaena was evident in spring and winter,whereas Dolichospermum and Cylindrospermopsis,which prefer higher temperatures,thrived in summer and autumn.Additionally,non-algal turbidity and heterogeneity can potentially alter the competitive outcome among filamentous cyanobacteria or foster coexistence under conditions of elevated temperatures and nutrient limitation.This study predicts that filamentous cyanobacteria may spread and persist in lakes spanning a wide trophic range.Current findings enhance our comprehen-sion of the dynamic responses exhibited by filamentous bloom-forming cyanobacteria in the face of environmental changes within shallow eutrophic lakes and provide valuable insights for lake managers involved in the remediation of degraded shallow lakes.
文摘In real world applications the supply, the demand and the transportation cost per unit of the quantities in a transportation problem are hardly specified precisely because of the changing economic and environmental conditions. It is also important that the time required for transportation should be minimum. In this paper a method has been proposed for the minimization of transportation costs. Supply and transportation costs per unit of the quantities are also determined. The present study was carried out to evaluate the quality of gravel to know its suitability for aggregate (raw material for concrete and road). The samples of gravel were analyzed for petrographic, physical, mechanical and chemical properties. Samples were categorized as quartzite group and carbonate group according to ASTM standard 295. Among these, samples of quartzite group were found dominant. The petrography examination of gravels which was carried out constituted of opal, tridymite, chalcedony, crystobalite and alkali carbonates rocks. Those minerals react with alkalis in cement leading to expansion and cracking of concrete. Other components such as sulfides, sulfates, halites, iron oxides, clay minerals and anhydrites are examined, which might be present as coating and impurities. The present study indicated that all samples are suitable for concrete making and obtain the optimum solution for transporting these materials from quarries to cities with minimum cost according to Egyptian Code.
基金National Natural Science Foundation of China(Grant Nos.52174080 and 51974160)Science Foundation of Tiandi Technology Co.,Ltd.(2022-2-TD-ZD016).
文摘During the mining process of impact-prone coal seams,drilling pressure relief can reduce the impact propensity of the coal seam,but it also reduces the integrity and strength of the coal mass at the side of the roadway.Therefore,studying the mechanical properties and energy evolution rules of coal samples containing holes and filled structures has certain practical significance for achieving coordinated control of coal mine rockburst disasters and the stability of roadway surrounding rocks.To achieve this aim,seven types of burst-prone coal samples were prepared and subject to uniaxial compression experiments with the aid of a TAW-3000 electro-hydraulic servo testing machine.Besides,the stress–strain curves,acoustic emission signals,DIC strain fields and other data were collected during the experiments.Furthermore,the failure modes and energy evolutions of samples with varying drilled hole sizes and filling materials were analyzed.The results show that the indexes related to burst propensity of the drilled coal samples decline to some extent compared with those of the intact one,and the decline is positively corelated to the diameter of the drilled hole.After hole filling,the strain concentration degree around the drilled hole is lowered to a certain degree,and polyurethane filling has a more remarkable effect than cement filling.Meanwhile,hole filling can enhance the strength and deformation resistance of coal.Hole drilling can accelerate the release of accumulated elastic strain energy,turning the acoustic emission events from low-frequency and high-energy ones to high-frequency and low-energy ones,whereas hole filling can reduce the intensity of energy release.The experimental results and theoretical derivation demonstrate that hole filling promotes coal deformability and strength mainly by weakening stress concentration surrounding the drilled holes.Moreover,the fillings can achieve a better filling effect if their elastic modulus and Poisson’s ratio are closer to those of the coal body.
文摘The nature of rock fragmentation affects the downstream mining processes like loading, hauling, and crushing the blasted rock. Therefore, it is important to evaluate rock fragmentation after blasting for choosing or designing optimal strategies for these processes. However, current techniques of rock fragmentation analysis such as sieving, image-based analysis, empirical methods or artificial intelligence-based methods entail different practical challenges, for example, excessive processing time, higher costs, applicability issues in underground environments, user-biasness, accuracy issues, etc. A classification model has been developed by utilizing image analysis techniques to overcome these challenges. The model was tested on about 7500 videos of load-haul-dump (LHD) buckets with blasted material from Malmberget iron ore mine in Sweden. A Kernel-based support vector machine (SVM) method was utilized to extract frames comprising loaded LHD buckets. Then, the blasted rock in the buckets was classified into five distinct categories using the bagging k-nearest neighbor (KNN) technique. The results showed 99.8% and 89.8% accuracy for kernel-based SVM and bagging KNN classifiers, respectively. The developed framework is efficient in terms of the operation time, cost and practicability for different mines and variate amounts of rock masses.
基金the financial support of the National Science Foundation(NSF EPSCoR RII Grant No.OIA-1632899)。
文摘Generation of hydroxyl radicals(·OH)is the basis of advanced oxidation process(AOP).This study investigates the catalytic activity of microporous carbonaceous structure for in-situ generation of·OH radicals.Biochar(BC)was selected as a representative of carbon materials with a graphitic structure.The work aims at assessing the impact of BC structure on the activation of H2O_(2),the reinforcement of the persistent free radicals(PFRs)in BC using heavy metal complexes,and the subsequent AOP.Accordingly,three different biochars(raw,chemically-and physiochemically-activated BCs)were used for adsorption of two metal ions(nickel and lead)and the degradation of phenol(100 mg/L)through AOP.The results demonstrated four outcomes:(1)The structure of carbon material,the identity and the quantity of the metal complexes in the structure play the key roles in the AOP process.(2)the quantity of PFRs on BC significantly increased(by 200%)with structural activation and metal loading.(3)Though the Pb-loaded BC contained a larger quantity of PFRs,Ni-loaded BC exhibited a higher catalytic activity.(4)The degradation efficiency values for phenol by modified biochar in the presence of H2O_(2) was 80.3%,while the removal efficiency was found to be 17%and 22%in the two control tests,with H2O_(2)(no BC)and with BC(no H2O_(2)),respectively.Overall,the work proposes a new approach for dual applications of carbonaceous structures;adsorption of metal ions and treatment of organic contaminants through in-situ chemical oxidation(ISCO).
基金funded by National Nature Science Foundation of China(41372096 and 40972066)
文摘The Talate Pb-Zn deposit,located in the east of the NW-SE extending Devonian Kelan volcanic-sedimentary basin of the southern Altaides,occurs in the metamorphic rock series of the upper second lithological section of the lower Devonian lower Kangbutiebao Formation（D_1k_1~2）.The Pb-Zn orebodies are stratiform and overprinted by late sulfide—quartz veins.Two distinct mineralization periods were identified：a submarine volcanic sedimentary exhalation period and a metamorphic hydrothermal mineralization period.The metamorphic overprinting period can be further divided into two stages：an early stage characterized by bedding-parallel lentoid quartz veins developed in the chlorite schist and leptite of the ore-bearing horizon,and a late stage represented by pyritechalcopyrite-quartz veins crosscutting chlorite schist and leptite or the massive Pb-Zn ores.Fluid inclusions in the early metamorphic quartz veins are mainly CO_2-H_2O-NaCI and carbonic（CO_2±CH_4±N_2） inclusions with minor aqueous inclusions.The CO_2-H_2O-NaCl inclusions have homogenization temperatures of 294-368℃,T_（m,CO2） of-62.6 to-60.5℃,T_（h,CO2） of 7.7 to 29.6℃（homogenized into liquid）,and salinities of 5.5-7.4 wt%NaCl eqv.The carbonic inclusions have T_（m,CO2）of-60.1 to-58.5℃,and T_（h,Co2） of-4.2 to 20.6℃.Fluid inclusions in late sulfide quartz veins are also dominated by CO_2-H_2O-NaCl and CO_2±CH_4 inclusions.The CO_2-H_2O-NaCl inclusions have T_（b,tot） of142 to 360℃,T_（m,CO2）of-66.0 to-56.6℃,T_（h,CO2） of-6.0 to 29.4℃（homogenized into liquid） and salinities of 2.4-16.5 wt%NaCl eqv.The carbonic inclusions have T_（m,Co2）of-61.5 to-57.3℃,and T_（h,CO2） of-27.0to 28.7℃.The aqueous inclusions（L-V） have T_（m,ice） of-9.8 to-1.3℃ and T_（h,tot） of 205 to 412℃.The P-T trapping conditions of CO_2-rich fluid inclusions（100-370 MPa,250-368℃） are comparable with the late- to post-regional metamorphism conditions.The CO_2-rich fluids,possibly derived from regional metamorphism,were involved in the reworking and metal enrichment of the primary ores.Based on these results,the Talate Pb-Zn deposit is classified as a VMS deposit modified by metamorphic fluids.The massive Pb-Zn ores with banded and breccia structures were developed in the early period of submarine volcanic sedimentary exhalation associated with an extensional subduction-related back-arc basin,and the quartz veins bearing polymetallic sulfides were formed in the late period of metamorphic hydrothermal superimposition related to the Permian-Triassic continental collision.
基金financial support provided by the Western US Mining Safety and Health Training&Translation Center by the National Institute for Occupational Safety and Health(NIOSH)
文摘The diesel particulate matter(DPM) emission from diesel powered equipment in underground mines can cause health hazards including cancer to the miners. The understanding of the DPM propagation pattern under realistic mining condition is required for selecting proper DPM control strategies and to improve working practices in underground mines. In this paper, three dimensional simulations of DPM emission from the exhaust tail pipe of a load-haul-dump(LHD) vehicle and its subsequent distribution inside an isolated zone in the typical underground mine are carried out using two different solution models available in Ansys Fluent. The incoming fresh air into the isolated zone is treated as a continuous phase and DPM is treated either as a continuous phase(gas) or as a secondary discrete phase(particle). Species transport model is used when DPM is treated as gas and discrete phase model is used when DPM is assumed to behave like a particle. The distributions of DPM concentration inside the isolated zone obtained from each method are presented and compared. From the comparison results, an accurate and economical solution technique for DPM evaluation can be selected.
基金the Western US Mining Safety and Health Training & Translation Center by the National Institute for Occupational Safety and Health (NIOSH) (No. 1R25OH008319)
文摘Diesel particulate matter(DPM) is considered carcinogenic after prolonged exposure. This paper used computational fluid dynamics(CFD) method to study the effect of four auxiliary ventilation systems on DPM distribution in a dead-end entry with loading operation. The auxiliary ventilation systems considered include: blower fan and tubing; exhaust fan and tubing, jet fan, and push–pull system. A species transport model with buoyancy effect was used to examine the DPM dispersion pattern with unsteady state analysis. During the 200 s of the loading operation, high DPM levels were identified in the face and dead-end entry regions. This study can be used for mining engineer as guidance to design and setup of local ventilation. It can also be used for selection of DPM control strategies and DPM annual training for underground miners.
基金the fund supports from the Fundamental Research Funds for the Central Universities(JD2326).
文摘The effects of substrate mingling ratio(SMR)(1:1,1:2,1:3,3:1,and 2:1)and organic loading rate(OLR)(50-90 g total solids per liter per day)on anaerobic co-digestion performance and microbial characteristics were investigated for pig manure(PM)and pretreated/untreated corn stover in batch and semicontinuous anaerobic digestion(AD)system.The results showed that SMR and pretreatment affected co-digestion performance.The maximum cumulative methane yield of 428.5 ml·g^(-1)(based on volatile solids(VS))was obtained for PCP13,which was 35.7%and 40.0%higher than that of CSU and PM.In the first 5 days,the maximum methane yield improvement rate was 378.1%for PCP13.The daily methane yield per gram VS of PCP13 was 11.4%-18.5%higher than that of PC_(U)13.Clostridium_sensu_stricto_1,DMER64,and Bacteroides and Methanosaeta,Methanobacterium,and Methanospirillum had higher relative abundance at the genus level.Therefore,SMR and OLR are important factor affecting the AD process,and OLR can affect methane production through volatile fatty acids.
基金Funded by the National Natural Science Foundation of China(Nos.20504018,20972014,20604010,20872010 and 20732004)the National Basic Research Program of China(No.2009CB930203)
文摘Chitosan-stavudine （d4T） conjugate with a succinic spacer was synthesized via carbodiimide coupling reaction and structurally characterized. In order to nanosize it for improving its therapeutic properties, the chitosan-5＇-O-succinyl-d4T conjugate was crosslinked with sodium tripolyphosphate （TPP） to obtain the chitosan-d4T conjugate nano-prodrug. The morphologies of chitosan-d4T conjugate nanoparticles were observed by transmission electron microscopy （TEM）, and their zeta potential, particle size, and polydispersity （size distribution） were measured by the dynamic light scattering （DLS） techniques. In vitro drug release studies at pH 1.1 and pH 7.4 indicate that the crosslinked chitosan-d4T conjugate nano-prodrug can prevent the coupled d4T from leaking out before entering the target viral reservoirs and provide a mild sustained release without the burst release. The results reveal that constructing conjugated chitosan nano-prodrugs may be a promising approach for improving the therapy efficacy of drugs in antiviral treatment.
基金supported by the National Key Research and Development Program of China under grant(2022YFE0206700)the financial support by the National Natural Science Foundation of China(52004320)the Science Foundation of China University of Petroleum,Beijing(2462021QNXZ012 and 2462021YJRC012)。
文摘Subsurface geothermal energy storage has greater potential than other energy storage strategies in terms of capacity scale and time duration.Carbon dioxide(CO_(2))is regarded as a potential medium for energy storage due to its superior thermal properties.Moreover,the use of CO_(2)plumes for geothermal energy storage mitigates the greenhouse effect by storing CO_(2)in geological bodies.In this work,an integrated framework is proposed for synergistic geothermal energy storage and CO_(2)sequestration and utilization.Within this framework,CO_(2)is first injected into geothermal layers for energy accumulation.The resultant high-energy CO_(2)is then introduced into a target oil reservoir for CO_(2)utilization and geothermal energy storage.As a result,CO_(2)is sequestrated in the geological oil reservoir body.The results show that,as high-energy CO_(2)is injected,the average temperature of the whole target reservoir is greatly increased.With the assistance of geothermal energy,the geological utilization efficiency of CO_(2)is higher,resulting in a 10.1%increase in oil displacement efficiency.According to a storage-potential assessment of the simulated CO_(2)site,110 years after the CO_(2)injection,the utilization efficiency of the geological body will be as high as 91.2%,and the final injection quantity of the CO_(2)in the site will be as high as 9.529×10^(8)t.After 1000 years sequestration,the supercritical phase dominates in CO_(2)sequestration,followed by the liquid phase and then the mineralized phase.In addition,CO_(2)sequestration accounting for dissolution trapping increases significantly due to the presence of residual oil.More importantly,CO_(2)exhibits excellent performance in storing geothermal energy on a large scale;for example,the total energy stored in the studied geological body can provide the yearly energy supply for over 3.5×10^(7) normal households.Application of this integrated approach holds great significance for large-scale geothermal energy storage and the achievement of carbon neutrality.
文摘For many years planning and management of water resources involved modeling and simulation of temporally sequenced and stochastic hydrologic events. Rainfall process is one of such hydrologic events which calls for time series analysis to better understand interesting features contained in it. Many statistics-based methods are available to simulate and predict such a kind of time series. Autoregressive (AR), moving average (MA), autoregressive moving average (ARMA) and autoregressive integrated moving average (ARIMA) models are among those methods. In this study a search was conducted to identify and examine a capable stochastic model for annual rainfall series (over the period 1954-2015) of Debre Markos town, Ethiopia. For the historical series, normality and stationarity tests were conducted to check if the time series was from a normally distributed and stationary process. Shapiro-Wilk (SW), Anderson-Darling (AD) and Kolmogorov-Smirnov (KS) tests were among the normality tests conducted whereas, Augmented Dickey-Fuller (ADF), Phillips-Perron (PP) and Kwiatkowski-Phillips-Schmidt-Shin (KPSS) tests were among the stationarity tests. Based on the test results, logarithmic transformation and first order differencing were performed to bring the original series to a normal and stationary series. Results of model fitting showed that three models namely, AR (2), MA (1) and ARMA (2,1) were capable in describing the annual rainfall series. A diagnostic check was performed on model residuals and ARMA (2,1) was found to be the best model among the candidates. Furthermore, three information criteria: Akaike Information Criterion (AIC), the corrected Akaike Information Criterion (AICc) and Bayesian Information Criterion (BIC) were used to select the best model. In this regard, too, the least information discrepancy between the underlying process and the fitted model was obtained from ARMA (2,1) model. Hence, this model was considered as a better representative of the annual rainfall values and was used to predict five years ahead values. The mean absolute percentage error (MAPE) of the prediction was found to be less than 10%. Thus, ARMA (2,1) model could be used for forecasting and simulation of annual rainfall for planning, management and design of water resources systems in Debre Markos town.
基金financial support provided by the Western US Mining Safety and Health Training & Translation Center by the National Institute for Occupational Safety and Health of America (NIOSH) (No.1R25OH008319)
文摘Diesel particulate matter(DPM) is a by-product from operating diesel engines. Since diesel powers are one of the major sources of energy for mobile underground mining equipment, the adverse health effects of DPM are of a great concern. This paper used computational fluid dynamics(CFD) method to study the effect of entry inclination on DPM plume distribution in a dead end entry. An upward mining face and a downward mining face were built with a truck and a loader in loading operation close to the face area. A species transport model with incorporated buoyancy effect was used to examine the DPM dispersion pattern for the above steady-state scenarios. High DPM and temperature regions were identified for the two different faces. The model was used to assess the role of auxiliary ventilation in reducing DPM exposures of underground miners working in those entries. In this study, it is suggested to provide local ventilation at least three times of the diesel exhaust rate to be able to lower the average DPM level for the mining upward face. The requirement for local ventilation is much less for the mining downward face. This can provide guidelines for good working practices and selection of diesel emission reduction technologies underground.
文摘Relative radiometric normalization (RRN) minimizes radiometric differences among images caused by inconsistencies of acquisition conditions rather than changes in surface. Scale invariant feature transform (SIFT) has the ability to automatically extract control points (CPs) and is commonly used for remote sensing images. However, its results are mostly inaccurate and sometimes contain incorrect matching caused by generating a small number of false CP pairs. These CP pairs have high false alarm matching. This paper presents a modified method to improve the performance of SIFT CPs matching by applying sum of absolute difference (SAD) in a different manner for the new optical satellite generation called near-equatorial orbit satellite and multi-sensor images. The proposed method, which has a significantly high rate of correct matches, improves CP matching. The data in this study were obtained from the RazakSAT satellite a new near equatorial satellite system. The proposed method involves six steps: 1) data reduction, 2) applying the SIFT to automatically extract CPs, 3) refining CPs matching by using SAD algorithm with empirical threshold, and 4) calculation of true CPs intensity values over all image’ bands, 5) preforming a linear regression model between the intensity values of CPs locate in reverence and sensed image’ bands, 6) Relative radiometric normalization conducting using regression transformation functions. Different thresholds have experimentally tested and used in conducting this study (50 and 70), by followed the proposed method, and it removed the false extracted SIFT CPs to be from 775, 1125, 883, 804, 883 and 681 false pairs to 342, 424, 547, 706, 547, and 469 corrected and matched pairs, respectively.
基金supported by Japanese Government(Monbukagakusho,MEXT)Scholarship in 2012.
文摘One of the major limitations of using Interferometric Synthetic Aperture Radar(InSAR)in time series analysis is the low-phase coherence associated with rough terrain and vegetated areas,which results in limited spatial coverage in such regions.Permanent scatterers technique was introduced to overcome this limitation using time-series analysis.However,identifying major scatterers within a pixel requires the single-looked pixels oversampling which can be a demanding process especially with large interferometric stacks and vast study areas.Therefore,using multilooked temporal coherent pixels was proposed to increase processing efficiency and coverage by utilizing distributed targets,but this technique may exclude pixels with reliable phase returns because of their temporal varying neighboring pixels.In this paper,we propose a technique to identify multilooked temporal stable pixels with reliable phase returns independent of their neighboring pixels.We conduct a simulation analysis to relate the spatial coherence of a pixel with its expected temporal correlation in the time series analysis module.We found that a liberal temporal correlation threshold of 0.53 in multilooked pixels stack is equivalent to a spatial coherence threshold of 0.2 when using number of looks of 9,which is considered acceptable in temporal coherent pixels,in terms of phase standard deviation.Applying these findings to study the 2011 Tohoku earthquake in the northeastern part of Japan resulted in increasing the number of usable pixels and spatial coverage index by nearly 50.4%and 36.8%,respectively,compared to the temporal coherent pixels.Furthermore,we propose an approach to integrate GPS observations with InSAR time series analysis,which resulted in deformation maps of the megathrust 2011 Tohoku earthquake with mean RMSE of 11.4 mm and a correlation of 98%in comparison to GPS observations.
基金Project supported by the Foundation of State Key Laboratory of Chemical Resource Engineering (2008-2009)
文摘The water repellence and mechanical properties of the gelatin/Ce（Ⅲ） fiber（GCe fiber） were improved by heat treatment,which was an easy and non-toxic method.The microscopic morphology,mechanical properties,antibacterial activity,and cell culture of the GCe fibers by heat treatment（HGCe fiber） were investigated.It was found that the water repellence and mechanical properties of the HGCe fibers increased significantly along with temperature increase.SEM observation showed that HGCe fibers had a fairly smooth surface and a compact structure.Detailed characterization revealed that the HGCe fibers exhibited similar antibacterial activity with the GCe fibers against Staphylococcus aureus.In addition,the results of cell culture by morphological assessment and methylthiazolyl tetrazolium assay（MTT assay） indicated the good biocompatibility of GCe fibers.Therefore,the HGCe fibers could be a promising candidate biomaterial for biomedicine applications.
