Critical information literacy is a new and important direction of information literacy education for university students in the new media era.By comparing critical information literacy between China and the West,combi...Critical information literacy is a new and important direction of information literacy education for university students in the new media era.By comparing critical information literacy between China and the West,combining with the research on information literacy education in China in the past 20 years,and based on the three major relationships that Chinese philosophy is concerned about that people need to face in the world of life,i.e.,the individual and the self,the individual and nature,and the individual and the society,this paper defines critical information literacy as that individuals,as information subjects,discover,select,confirm,and evaluate the information they are exposed to by obtaining and discriminating the content elements of the information world(information sources,information,and information assets)and using critical thinking skills and methods,creatively interpret or solve the relevant problems arising from the interaction between individuals and self,individuals and nature,individuals and society,and form the literacy that represents the knowledge,ability,attitude,habit,and level of the information subject through continuous reflection and practice.In order for human beings to better understand the world and construct it responsibly,critical information literacy can play a greater role and educational value.It not only helps contemporary college students build knowledge of“good questioning”and enhance their“reasoning”skills,but also encourages them to maintain a“firm standpoint,”cultivate a habit of“healthy skepticism,”and enhance their“decision-making”skills.展开更多
Based on the important role in mine safety played by parameters of the first gas outburst, we propose a method of combining historic data, theoretical analysis and experimental research for the purpose of crit- ical v...Based on the important role in mine safety played by parameters of the first gas outburst, we propose a method of combining historic data, theoretical analysis and experimental research for the purpose of crit- ical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine. According to a characteristic analysis and a summary of the rules of coal and gas outbursts in the No.8 coal seam of a Hua- inan mine, we have investigated their effect on coal and gas outbursts in terms such as ground stress, gas, and coal structure. We have selected gas parameters and determined the critical values of each of the fol- lowing indices: gas content as 7.7 m^3/t, tectonic coal as 0.8 m thick, the absolute gas emission as 2 m3/min, the rate of change as 0.7 m3/min, the gas desorption index of a drilling chip KI as 0.26 mL/(g min^1/2) and the values of desorption indexes Ah2 as 200 Pa. From a verification of the production, the results indicate that application of each index and their critical values significantly improve the level of safety in the pro- duction process, relieve the burden upon the mine, save much labor and bring clear economic benefits.展开更多
Soil and tissue analyses are usually used in identifying potassium(K) deficiencies and predicting K fertilizer requirements of crops.The critical levels of both soil and fresh leaf tissue at seventh leaf stage were de...Soil and tissue analyses are usually used in identifying potassium(K) deficiencies and predicting K fertilizer requirements of crops.The critical levels of both soil and fresh leaf tissue at seventh leaf stage were developed and assessed for canola,chickpea and sunflower grown on two Saskatchewan,soils,with six rates of K fertilizer supply, in a growth chamber experiment.The available potassium in soils was determined by two methods:1)resin strip extraction, and 2) NH4OAC extraction. The potassium in fresh leaves was determined at seventh leaf stage by a simple procedure using a common garlic press and injector to extract the plant sap and testing the sap with a handheld ion selection electrode meter. The results shoWed significant relationships between the resin strip extractable K and NH4OAC extractable K, and between the plant uptake of total K and the supply of available K in the soils determined by the two methods. Good relationships were also found between the potassium in fresh leaves and the plant uptake of total K for canola, chickpea and sunflower.The resin strip extraction for K was calibrated using common NH4OAC extraction, and recommended for routine analyses because of its simplicity and sensitivity.展开更多
Analysis and comparison of Jiaozhou Bay data collected from May 1991 to February 1994 revealed the spatiotemporal variations of the ambient Si(OH) 4∶NO 3 (Si∶N) concentration ratios and the seasonal variations of (S...Analysis and comparison of Jiaozhou Bay data collected from May 1991 to February 1994 revealed the spatiotemporal variations of the ambient Si(OH) 4∶NO 3 (Si∶N) concentration ratios and the seasonal variations of (Si∶N) ratios in Jiaozhou Bay and showed that the Si∶N ratios were < 1 throughout Jiaozhou Bay in spring, autumn, and winter. These results provide further evidence that silicate limits the growth of phytoplankton (i.e. diatoms) in spring, autumn and winter. Moreover, comparison of the spatiotemporal variations of the Si∶N ratio and primary production in Jiaozhou Bay suggested their close relationship. The spatiotemporal pattern of dissolved silicate matched well that of primary production in Jiaozhou Bay. Along with the environmental change of Jiaozhou Bay in the last thirty years, the N and P concentrations tended to rise, whereas Si concentration showed cyclic seasonal variations. With the variation of nutrient Si limiting the primary production in mind, the authors found that the range of values of primary production is divided into three parts: the basic value of Si limited primary production, the extent of Si limited primary production and the critical value of Si limited primary production, which can be calculated for Jiaozhou Bay by Equations (1), (2) and (3), showing that the time of the critical value of Si limitation of phytoplankton growth in Jiaozhou Bay is around November 3 to November 13 in autumn; and that the time of the critical value of Si satisfaction of phytoplankton growth in Jiaozhou Bay is around May 22 to June 7 in spring. Moreover, the calculated critical value of Si satisfactory for phytoplankton growth is 2.15-0.76 μmol/L and the critical value of Si limitation of phytoplankton growth is 1.42-0.36 μmol/L; so that the time period of Si limitation of phytoplankton growth is around November 13 to May 22 in the next year; the time period of Si satisfactory for phytoplankton growth is around June 7 to November 3. This result also explains why critical values of nutrient silicon affect phytoplankton growth in spring and autumn are different in different waters of Jiaozhou Bay and also indicates how the silicate concentration affects the phytoplankton assemblage structure. The dilution of silicate concentration by seawater exchange affects the growth of phytoplankton so that the primary production of phytoplankton declines outside Jiaozhou Bay earlier than inside Jiaozhou Bay by one and half months. This study showed that Jiaozhou Bay phytoplankton badly need silicon and respond very sensitively and rapidly to the variation of silicon.展开更多
Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. ...Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. A circular zone counting (CZC) method is proposed in this paper, by combining the Duffing oscillator's phase trajectory feature and numerical calculation for quickly and accurately identifying state transition and determining the critical value, to realize a high- efficiency weak signal detection. Detailed model analysis and method construction of the CZC method are introduced. Numerical experiments into the reliability of the proposed CZC method compared with the maximum Lyapunov exponent (MLE) method are carried out. The CZC method is demonstrated to have better detecting ability than the MLE method, and furthermore it is simpler and clearer in calculation to extend to engineering application.展开更多
A series of AZ80 billets were compressed with 60%height reduction on hot process simulator at 250,300,350,400℃ under strain rates of 0.01,0.1,1 and 10 s- 1.In order to predict the occurrence of surface fracture,the v...A series of AZ80 billets were compressed with 60%height reduction on hot process simulator at 250,300,350,400℃ under strain rates of 0.01,0.1,1 and 10 s- 1.In order to predict the occurrence of surface fracture,the values of the Cockcroft-Latham equation were calculated by the corresponding finite element numerical algorithm developed.A concept about damage incremental ratio in plastic deformation was defined as the ratio of damage increment at one step to the accumulated value.A method of finding the intersection of incremental ratio varying curve and simulation step axis was brought forward to make the fracture step certain. Then,the effects of temperature and strain rate on critical damage value were achieved.The results show that the critical damage value is not a constant but changes in a range of 0.021 8-0.378 0.It decreases significantly with the increase of strain rate at a certain temperature.While under a certain strain rate,the critical damage value has little change with the increase of temperature.展开更多
The optimized management of crop fertilization is very important for improving crop yield and reducing the consumption of chemical fertilizers.Critical nutrient values can be used for evaluating the nutritional status...The optimized management of crop fertilization is very important for improving crop yield and reducing the consumption of chemical fertilizers.Critical nutrient values can be used for evaluating the nutritional status of a crop,and they reflect the nutrient concentrations above which the plant is sufficiently supplied for achieving the maximum potential yield.Based on on-farm surveys of 504 farmers and 60 field experimental sites in the drylands of China,we proposed a recommended fertilization method to determine nitrogen(N),phosphorus(P),and potassium(K)fertilizer input rates for wheat production,and then validated the method by a field experiment at 66 different sites in northern China.The results showed that wheat grain yield varied from 1.1 to 9.2 t ha^(-1),averaging 4.6 t ha^(-1),and it had a quadratic relationship with the topsoil(0-20 cm)nitrate N and soil available P contents at harvest.However,yield was not correlated with the inputs of N,P,and K fertilizers.Based on the relationship(exponential decay model)between 95–105%of the relative yield and topsoil nitrate N,available P,and available K contents at wheat harvest from 60 field experiments,the topsoil critical nutrient values were determined as 34.6,15.6,and 150 mg kg^(-1)for soil nitrate N,available P,and available K,respectively.Then,based on five groups of relative yield(>125%,115–125%,105–115%,95–105%,and<95%)and the model,the five groups of topsoil critical nutrient levels and fertilization coefficients(Fc)were determined.Finally,we proposed a new method for calculating the recommended fertilizer input rate as:Fr=Gy×Nr×Fc,where Fr is the recommended fertilizer(N/P/K)input rate;Gy is the potential grain yield;Nr is the N(N_(rN)),P(N_(rP)),and K(N_(rK))nutrient requirements for wheat to produce 1,000 kg of grain;and Fc is a coefficient for N(N_c)/P(P_c)/K(K_c)fertilizer.A 2-year validated experiment confirmed that the new method reduced N fertilizer input by 17.5%(38.5 kg N ha^(-1))and P fertilizer input by 43.5%(57.5 kg P_(2)O_(5) ha^(-1))in northern China and did not reduce the wheat yield.This outcome can significantly increase the farmers’benefits(by 7.58%,or 139 US$ha^(-1)).Therefore,this new recommended fertilization method can be used as a tool to guide N,P,and K fertilizer application rates for dryland wheat production.展开更多
In this paper, a new definition of structure system redundancy is proposed in view of the various measures for structure redundancy. By introducing the terms of structure system failure at the mechanism level and equi...In this paper, a new definition of structure system redundancy is proposed in view of the various measures for structure redundancy. By introducing the terms of structure system failure at the mechanism level and equivalent reliability index, the safety for existing offshore platforms can be evaluated by the semi-probabilistic method presented in this paper. Some numerical examples are given and satisfactory results have been obtained.展开更多
CO has been used widely in the production process of colliery as an index gas to predict spontaneous combustion of coal. But in some collieries there are CO gas in the upper corner of the face all the times, sometime ...CO has been used widely in the production process of colliery as an index gas to predict spontaneous combustion of coal. But in some collieries there are CO gas in the upper corner of the face all the times, sometime CO gas even exceeds the regulated critical index. This phenomenon is much more obvious in the fully-mechanized longwall face and fully-mechanized longwall and top-coal caving face. Although many measures of fire-proof and fire-extinguishing have been adopted, the flowing amount of CO gas can be only decreasd, but can not be eliminated completely. Using the different kinds of coal, the experiment of coal oxidation was made at the low temperature. The experiment indicates that some kinds of coal can produce CO under the condition of normal temperature oxidation, sometime the CO consistency is very high, and the intension of CO can be decreased with oxidation time prolonging. Selecting rational critical value of CO is the kev to predicting spontaneous combustion of coal correctly and reliably. The problem of selecting retional critical value of CO was studied. Finally, the amount of CO gas released by different kinds of coal was obtained under normal temperature condition.展开更多
Australian cotton production predominantly occurs on Vertisols.The average lint yield of cotton grown in Australia is 2260–2700 kg·hm^(−2),which is 2.5 to 3 times the world average.This high productivity per uni...Australian cotton production predominantly occurs on Vertisols.The average lint yield of cotton grown in Australia is 2260–2700 kg·hm^(−2),which is 2.5 to 3 times the world average.This high productivity per unit of land area requires efficient use of resources such as water and nutrients.However,high yields accelerate the export of nutrients such as phosphorus(P)in seed,depleting the soil reserves of P more than in other countries with lower cotton yields.Recent surveys of cotton industry indicate that P application rates should match seed P export(30~40 kg·hm−2),but historical depletion within subsoil is still evident and is continuing.Depletion of soil P is typically more pronounced in the subsoil than in the topsoil(0~20 cm)where P fertiliser is applied,as cotton roots rely on these layers as important sources of plant available water and available P.This mismatch between zones of P uptake and resupply may increase stratification of available P in the soil profile.Recent studies showed that cotton responded poorly to banded applications of fertiliser P,while dispersal of fertiliser throughout the plant beds was more successful.Researchers have also observed sporadic cotton responses to applied P fertiliser in soils where available P concentrations were well above the previously determined critical concentrations indicative of fertiliser P responses in Australia.To sustain highyielding cotton production in Australia,a greater understanding of cotton root acquisition of applied P,as well as a re-examination of critical soil P concentrations for each production region are required.展开更多
Since the implementation of several pilot production tests were in natural gas hydrate(NGH) reservoirs in terrestrial and marine settings, the study of NGH has entered a new stage of technological development for indu...Since the implementation of several pilot production tests were in natural gas hydrate(NGH) reservoirs in terrestrial and marine settings, the study of NGH has entered a new stage of technological development for industrial exploitation. Prior to the industrial exploitation of any given NGH reservoir, the economic feasibility should be examined. The first step of economic evaluation of a NGH reservoir is to know whether its resource amount meets the requirement for industrial exploitation. Unfortunately, few relevant studies have been conducted in this regard. In this study, the net present value(NPV) method is employed to estimate the economic critical resources required for the industrial exploitation of NGHs under different production scenarios. Sensitivity analysis is also performed in order to specify the effects of key factors, such as the number of production wells, gas price, technological improvement and tax incentive, on the economic critical resources. The results indicate that China requires the lowest economic critical resource for a NGH reservoir to be industrially exploited, ranging from 3.62 to 24.02 billion m3 methane. Changes in gas price and tax incentives also play significant roles in affecting the threshold and timeline for the industrial exploitation of NGH.展开更多
An embedded cylinder is a large-diameter cylinder embedded in a soil foundation. The state of failure of such an embedded cylindrical structure shows large deflection instead of slide and overturn of the traditional g...An embedded cylinder is a large-diameter cylinder embedded in a soil foundation. The state of failure of such an embedded cylindrical structure shows large deflection instead of slide and overturn of the traditional gravity type of structure placed on a rubble base or foundation base. The critical value of deflection of the embedded cylindrical structure, which is the maximum allowable deflection for stability calculation of the cylinder, is a vital control value. Through investigation on deflection and soil pressures on an embedded cylinder by model experiments, the variations of the angle of rotation θ of a cylinder with effective anti-overturning ratio η and moment MH of thrust are discussed. On the basis of experimental study, the critical value of deflection of the cylindrical structure is proposed in the paper. Meanwhile, the formulas for calculating deflection of cylinders are derived.展开更多
In order to generalize Hadamard's theory of fundamental solutions to the case of degenerate holomorphic PDE, this paper studies the asymptotic expansion of Dirac-type distribution associated with a class of hypers...In order to generalize Hadamard's theory of fundamental solutions to the case of degenerate holomorphic PDE, this paper studies the asymptotic expansion of Dirac-type distribution associated with a class of hypersurfaces F(x) with degenerate critical points and proves that [F(x)](+)(lambda) is a distribution-valued meromorphic of lambda is an element of C under some assumptions on F(x). Next, the authors use the Normal form theory of Arnold and prove that for a hypersurface F(x) = 0 with A(mu) type degenerate critical point at x = 0, F-+(lambda) is a distribution-valued meromorphic function of lambda.展开更多
The purpose of this paper is to study the singular values and real fixed points of one parameter family of function,fλ(z)=λab2/b2-1,fλ(0)=λ/lnb for λ∈R/{0},z∈C and b〉 0 except b = 1. It is found that the ...The purpose of this paper is to study the singular values and real fixed points of one parameter family of function,fλ(z)=λab2/b2-1,fλ(0)=λ/lnb for λ∈R/{0},z∈C and b〉 0 except b = 1. It is found that the function fλ(z) has infinitely many singular values for all b 〉 0 except b = 1. It is also shown that, for 0 〈 b 〈 1, all the critical values of fλ(z) lie in the left half plane while, for b 〉 1, lie in the right half plane. Further, it is seen that all these critical values are outside the open disk centered at origin and having radius |λ/lnb|for all b 〉 0 except b = 1. Moreover, the real fixed points of fλ (z) and their nature are investigated.展开更多
In this paper the concepts of the boundary value problem of abstract kinetic equation with the first kind of critical parameter γ 0 and generalized periodic boundary conditions are introduced in a Lebesgue space whic...In this paper the concepts of the boundary value problem of abstract kinetic equation with the first kind of critical parameter γ 0 and generalized periodic boundary conditions are introduced in a Lebesgue space which consists of functions with vector valued in a general Banach space, and then describe the solution of these abstract boundary value problem by the abstract linear integral operator of Volterra type. We call this process the integral operator solving process.展开更多
The paper conducts Critical Discourse Analysis on the use of Modality in political interviews. The purpose of this study is to investigate whether the use of Motlality is driven by the speakers' ideology, and thus...The paper conducts Critical Discourse Analysis on the use of Modality in political interviews. The purpose of this study is to investigate whether the use of Motlality is driven by the speakers' ideology, and thus helps lo build the power relationships between the two participants. Such a linguistic awareness can inform a capacity to resist and change exploitative and dominating linguistic practices, and it' s an issue of importance to everyone with a concem and interest in the problems of our contemporary society. With such awareness, people can get a more incisive recogni-tion and judgment of the political implications, and correctly acquire new trends in politics and developnient of current affairs.展开更多
Objective:This paper aims to investigate the value of individualized care for critically ill patients receiving continuous blood purification therapy.Methods:89 cases of critically ill patients who were treated from J...Objective:This paper aims to investigate the value of individualized care for critically ill patients receiving continuous blood purification therapy.Methods:89 cases of critically ill patients who were treated from June 2021 to June 2023 were randomly divided into groups,with individualized care in group A and routine care in group B.The differences in clinical indicators,purification effect,quality of life,and complications of blood purification were compared between the groups.Results:Heart rate,respiration,body temperature,and other indicators in group A were better than those in group B,P<0.05.C-reactive protein(CRP),β2-microglobulin(β2-MG),blood urea nitrogen(BUN),and phosphorus(P)in group A were lower than those in group B,P<0.05.Group A had higher quality of life than Group B,P<0.05.The complication rate of blood purification in Group A was lower than that in Group B,P<0.05.Conclusion:During continuous blood purification in critically ill patients,individualized nursing intervention can enhance the effect of blood purification,improve the physiological indicators of patients,and reduce the complications of blood purification,which is highly effective and feasible.展开更多
基金Chinese Association of Higher Education Key Project“Research on Critical Information Literacy Education Strategies for College Students in the New Media Era”(23GR0211)。
文摘Critical information literacy is a new and important direction of information literacy education for university students in the new media era.By comparing critical information literacy between China and the West,combining with the research on information literacy education in China in the past 20 years,and based on the three major relationships that Chinese philosophy is concerned about that people need to face in the world of life,i.e.,the individual and the self,the individual and nature,and the individual and the society,this paper defines critical information literacy as that individuals,as information subjects,discover,select,confirm,and evaluate the information they are exposed to by obtaining and discriminating the content elements of the information world(information sources,information,and information assets)and using critical thinking skills and methods,creatively interpret or solve the relevant problems arising from the interaction between individuals and self,individuals and nature,individuals and society,and form the literacy that represents the knowledge,ability,attitude,habit,and level of the information subject through continuous reflection and practice.In order for human beings to better understand the world and construct it responsibly,critical information literacy can play a greater role and educational value.It not only helps contemporary college students build knowledge of“good questioning”and enhance their“reasoning”skills,but also encourages them to maintain a“firm standpoint,”cultivate a habit of“healthy skepticism,”and enhance their“decision-making”skills.
基金supported by the National Key Basic Research Program of China (No.2005CB 221501)the Innovation Scientists and Technicians Troop Construction Projects of Henan Province (No.084200510002)the Program for New Century Excellent Talents in University (No.NCET-07-0257)
文摘Based on the important role in mine safety played by parameters of the first gas outburst, we propose a method of combining historic data, theoretical analysis and experimental research for the purpose of crit- ical values of gas parameters of the first gas outburst in a coal seam of the Xieqiao Mine. According to a characteristic analysis and a summary of the rules of coal and gas outbursts in the No.8 coal seam of a Hua- inan mine, we have investigated their effect on coal and gas outbursts in terms such as ground stress, gas, and coal structure. We have selected gas parameters and determined the critical values of each of the fol- lowing indices: gas content as 7.7 m^3/t, tectonic coal as 0.8 m thick, the absolute gas emission as 2 m3/min, the rate of change as 0.7 m3/min, the gas desorption index of a drilling chip KI as 0.26 mL/(g min^1/2) and the values of desorption indexes Ah2 as 200 Pa. From a verification of the production, the results indicate that application of each index and their critical values significantly improve the level of safety in the pro- duction process, relieve the burden upon the mine, save much labor and bring clear economic benefits.
文摘Soil and tissue analyses are usually used in identifying potassium(K) deficiencies and predicting K fertilizer requirements of crops.The critical levels of both soil and fresh leaf tissue at seventh leaf stage were developed and assessed for canola,chickpea and sunflower grown on two Saskatchewan,soils,with six rates of K fertilizer supply, in a growth chamber experiment.The available potassium in soils was determined by two methods:1)resin strip extraction, and 2) NH4OAC extraction. The potassium in fresh leaves was determined at seventh leaf stage by a simple procedure using a common garlic press and injector to extract the plant sap and testing the sap with a handheld ion selection electrode meter. The results shoWed significant relationships between the resin strip extractable K and NH4OAC extractable K, and between the plant uptake of total K and the supply of available K in the soils determined by the two methods. Good relationships were also found between the potassium in fresh leaves and the plant uptake of total K for canola, chickpea and sunflower.The resin strip extraction for K was calibrated using common NH4OAC extraction, and recommended for routine analyses because of its simplicity and sensitivity.
文摘Analysis and comparison of Jiaozhou Bay data collected from May 1991 to February 1994 revealed the spatiotemporal variations of the ambient Si(OH) 4∶NO 3 (Si∶N) concentration ratios and the seasonal variations of (Si∶N) ratios in Jiaozhou Bay and showed that the Si∶N ratios were < 1 throughout Jiaozhou Bay in spring, autumn, and winter. These results provide further evidence that silicate limits the growth of phytoplankton (i.e. diatoms) in spring, autumn and winter. Moreover, comparison of the spatiotemporal variations of the Si∶N ratio and primary production in Jiaozhou Bay suggested their close relationship. The spatiotemporal pattern of dissolved silicate matched well that of primary production in Jiaozhou Bay. Along with the environmental change of Jiaozhou Bay in the last thirty years, the N and P concentrations tended to rise, whereas Si concentration showed cyclic seasonal variations. With the variation of nutrient Si limiting the primary production in mind, the authors found that the range of values of primary production is divided into three parts: the basic value of Si limited primary production, the extent of Si limited primary production and the critical value of Si limited primary production, which can be calculated for Jiaozhou Bay by Equations (1), (2) and (3), showing that the time of the critical value of Si limitation of phytoplankton growth in Jiaozhou Bay is around November 3 to November 13 in autumn; and that the time of the critical value of Si satisfaction of phytoplankton growth in Jiaozhou Bay is around May 22 to June 7 in spring. Moreover, the calculated critical value of Si satisfactory for phytoplankton growth is 2.15-0.76 μmol/L and the critical value of Si limitation of phytoplankton growth is 1.42-0.36 μmol/L; so that the time period of Si limitation of phytoplankton growth is around November 13 to May 22 in the next year; the time period of Si satisfactory for phytoplankton growth is around June 7 to November 3. This result also explains why critical values of nutrient silicon affect phytoplankton growth in spring and autumn are different in different waters of Jiaozhou Bay and also indicates how the silicate concentration affects the phytoplankton assemblage structure. The dilution of silicate concentration by seawater exchange affects the growth of phytoplankton so that the primary production of phytoplankton declines outside Jiaozhou Bay earlier than inside Jiaozhou Bay by one and half months. This study showed that Jiaozhou Bay phytoplankton badly need silicon and respond very sensitively and rapidly to the variation of silicon.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61172047 and 61071025)
文摘Identifying state transition and determining the critical value of the Duffing oscillator are crucial to indicating external signal existence and have a great influence on detection accuracy in weak signal detection. A circular zone counting (CZC) method is proposed in this paper, by combining the Duffing oscillator's phase trajectory feature and numerical calculation for quickly and accurately identifying state transition and determining the critical value, to realize a high- efficiency weak signal detection. Detailed model analysis and method construction of the CZC method are introduced. Numerical experiments into the reliability of the proposed CZC method compared with the maximum Lyapunov exponent (MLE) method are carried out. The CZC method is demonstrated to have better detecting ability than the MLE method, and furthermore it is simpler and clearer in calculation to extend to engineering application.
基金Projects(CSTC,cstc2009aa3012-1)supported by Science and Technology Committee of Chongqing,ChinaProject(20100470813)supported by China Postdoctoral Science FoundationProject(2010011511)supported by Sharing Fund of Chongqing University’s Large-scale Equipment
文摘A series of AZ80 billets were compressed with 60%height reduction on hot process simulator at 250,300,350,400℃ under strain rates of 0.01,0.1,1 and 10 s- 1.In order to predict the occurrence of surface fracture,the values of the Cockcroft-Latham equation were calculated by the corresponding finite element numerical algorithm developed.A concept about damage incremental ratio in plastic deformation was defined as the ratio of damage increment at one step to the accumulated value.A method of finding the intersection of incremental ratio varying curve and simulation step axis was brought forward to make the fracture step certain. Then,the effects of temperature and strain rate on critical damage value were achieved.The results show that the critical damage value is not a constant but changes in a range of 0.021 8-0.378 0.It decreases significantly with the increase of strain rate at a certain temperature.While under a certain strain rate,the critical damage value has little change with the increase of temperature.
基金supported by grants from the National Key Research and Development Program of China(2021YFD1900700 and 2018YFD0200401)the China Agricultural Research System(CARS-3)the Science and Technology Research Program of Shaanxi Province,China(2022PT-06)。
文摘The optimized management of crop fertilization is very important for improving crop yield and reducing the consumption of chemical fertilizers.Critical nutrient values can be used for evaluating the nutritional status of a crop,and they reflect the nutrient concentrations above which the plant is sufficiently supplied for achieving the maximum potential yield.Based on on-farm surveys of 504 farmers and 60 field experimental sites in the drylands of China,we proposed a recommended fertilization method to determine nitrogen(N),phosphorus(P),and potassium(K)fertilizer input rates for wheat production,and then validated the method by a field experiment at 66 different sites in northern China.The results showed that wheat grain yield varied from 1.1 to 9.2 t ha^(-1),averaging 4.6 t ha^(-1),and it had a quadratic relationship with the topsoil(0-20 cm)nitrate N and soil available P contents at harvest.However,yield was not correlated with the inputs of N,P,and K fertilizers.Based on the relationship(exponential decay model)between 95–105%of the relative yield and topsoil nitrate N,available P,and available K contents at wheat harvest from 60 field experiments,the topsoil critical nutrient values were determined as 34.6,15.6,and 150 mg kg^(-1)for soil nitrate N,available P,and available K,respectively.Then,based on five groups of relative yield(>125%,115–125%,105–115%,95–105%,and<95%)and the model,the five groups of topsoil critical nutrient levels and fertilization coefficients(Fc)were determined.Finally,we proposed a new method for calculating the recommended fertilizer input rate as:Fr=Gy×Nr×Fc,where Fr is the recommended fertilizer(N/P/K)input rate;Gy is the potential grain yield;Nr is the N(N_(rN)),P(N_(rP)),and K(N_(rK))nutrient requirements for wheat to produce 1,000 kg of grain;and Fc is a coefficient for N(N_c)/P(P_c)/K(K_c)fertilizer.A 2-year validated experiment confirmed that the new method reduced N fertilizer input by 17.5%(38.5 kg N ha^(-1))and P fertilizer input by 43.5%(57.5 kg P_(2)O_(5) ha^(-1))in northern China and did not reduce the wheat yield.This outcome can significantly increase the farmers’benefits(by 7.58%,or 139 US$ha^(-1)).Therefore,this new recommended fertilization method can be used as a tool to guide N,P,and K fertilizer application rates for dryland wheat production.
文摘In this paper, a new definition of structure system redundancy is proposed in view of the various measures for structure redundancy. By introducing the terms of structure system failure at the mechanism level and equivalent reliability index, the safety for existing offshore platforms can be evaluated by the semi-probabilistic method presented in this paper. Some numerical examples are given and satisfactory results have been obtained.
基金Science of Fire Natural Science Foundation of China(2001CB40960102)
文摘CO has been used widely in the production process of colliery as an index gas to predict spontaneous combustion of coal. But in some collieries there are CO gas in the upper corner of the face all the times, sometime CO gas even exceeds the regulated critical index. This phenomenon is much more obvious in the fully-mechanized longwall face and fully-mechanized longwall and top-coal caving face. Although many measures of fire-proof and fire-extinguishing have been adopted, the flowing amount of CO gas can be only decreasd, but can not be eliminated completely. Using the different kinds of coal, the experiment of coal oxidation was made at the low temperature. The experiment indicates that some kinds of coal can produce CO under the condition of normal temperature oxidation, sometime the CO consistency is very high, and the intension of CO can be decreased with oxidation time prolonging. Selecting rational critical value of CO is the kev to predicting spontaneous combustion of coal correctly and reliably. The problem of selecting retional critical value of CO was studied. Finally, the amount of CO gas released by different kinds of coal was obtained under normal temperature condition.
基金supported by funding from the Australian Government Department of Agriculture,Water and the Environment as a part of its Rural R&D for Profit programthe Cotton Research and Development Corporation through the “More profit from nitrogen:enhancing the nutrient use e ciency of intensive cropping and pasture systems” project.
文摘Australian cotton production predominantly occurs on Vertisols.The average lint yield of cotton grown in Australia is 2260–2700 kg·hm^(−2),which is 2.5 to 3 times the world average.This high productivity per unit of land area requires efficient use of resources such as water and nutrients.However,high yields accelerate the export of nutrients such as phosphorus(P)in seed,depleting the soil reserves of P more than in other countries with lower cotton yields.Recent surveys of cotton industry indicate that P application rates should match seed P export(30~40 kg·hm−2),but historical depletion within subsoil is still evident and is continuing.Depletion of soil P is typically more pronounced in the subsoil than in the topsoil(0~20 cm)where P fertiliser is applied,as cotton roots rely on these layers as important sources of plant available water and available P.This mismatch between zones of P uptake and resupply may increase stratification of available P in the soil profile.Recent studies showed that cotton responded poorly to banded applications of fertiliser P,while dispersal of fertiliser throughout the plant beds was more successful.Researchers have also observed sporadic cotton responses to applied P fertiliser in soils where available P concentrations were well above the previously determined critical concentrations indicative of fertiliser P responses in Australia.To sustain highyielding cotton production in Australia,a greater understanding of cotton root acquisition of applied P,as well as a re-examination of critical soil P concentrations for each production region are required.
基金the financial support provided by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030003)supported by the Department of Science and Technology of Guangdong Province,as well as project(DD20221703)supported by the China Geological Survey。
文摘Since the implementation of several pilot production tests were in natural gas hydrate(NGH) reservoirs in terrestrial and marine settings, the study of NGH has entered a new stage of technological development for industrial exploitation. Prior to the industrial exploitation of any given NGH reservoir, the economic feasibility should be examined. The first step of economic evaluation of a NGH reservoir is to know whether its resource amount meets the requirement for industrial exploitation. Unfortunately, few relevant studies have been conducted in this regard. In this study, the net present value(NPV) method is employed to estimate the economic critical resources required for the industrial exploitation of NGHs under different production scenarios. Sensitivity analysis is also performed in order to specify the effects of key factors, such as the number of production wells, gas price, technological improvement and tax incentive, on the economic critical resources. The results indicate that China requires the lowest economic critical resource for a NGH reservoir to be industrially exploited, ranging from 3.62 to 24.02 billion m3 methane. Changes in gas price and tax incentives also play significant roles in affecting the threshold and timeline for the industrial exploitation of NGH.
文摘An embedded cylinder is a large-diameter cylinder embedded in a soil foundation. The state of failure of such an embedded cylindrical structure shows large deflection instead of slide and overturn of the traditional gravity type of structure placed on a rubble base or foundation base. The critical value of deflection of the embedded cylindrical structure, which is the maximum allowable deflection for stability calculation of the cylinder, is a vital control value. Through investigation on deflection and soil pressures on an embedded cylinder by model experiments, the variations of the angle of rotation θ of a cylinder with effective anti-overturning ratio η and moment MH of thrust are discussed. On the basis of experimental study, the critical value of deflection of the cylindrical structure is proposed in the paper. Meanwhile, the formulas for calculating deflection of cylinders are derived.
文摘In order to generalize Hadamard's theory of fundamental solutions to the case of degenerate holomorphic PDE, this paper studies the asymptotic expansion of Dirac-type distribution associated with a class of hypersurfaces F(x) with degenerate critical points and proves that [F(x)](+)(lambda) is a distribution-valued meromorphic of lambda is an element of C under some assumptions on F(x). Next, the authors use the Normal form theory of Arnold and prove that for a hypersurface F(x) = 0 with A(mu) type degenerate critical point at x = 0, F-+(lambda) is a distribution-valued meromorphic function of lambda.
文摘The purpose of this paper is to study the singular values and real fixed points of one parameter family of function,fλ(z)=λab2/b2-1,fλ(0)=λ/lnb for λ∈R/{0},z∈C and b〉 0 except b = 1. It is found that the function fλ(z) has infinitely many singular values for all b 〉 0 except b = 1. It is also shown that, for 0 〈 b 〈 1, all the critical values of fλ(z) lie in the left half plane while, for b 〉 1, lie in the right half plane. Further, it is seen that all these critical values are outside the open disk centered at origin and having radius |λ/lnb|for all b 〉 0 except b = 1. Moreover, the real fixed points of fλ (z) and their nature are investigated.
文摘In this paper the concepts of the boundary value problem of abstract kinetic equation with the first kind of critical parameter γ 0 and generalized periodic boundary conditions are introduced in a Lebesgue space which consists of functions with vector valued in a general Banach space, and then describe the solution of these abstract boundary value problem by the abstract linear integral operator of Volterra type. We call this process the integral operator solving process.
文摘The paper conducts Critical Discourse Analysis on the use of Modality in political interviews. The purpose of this study is to investigate whether the use of Motlality is driven by the speakers' ideology, and thus helps lo build the power relationships between the two participants. Such a linguistic awareness can inform a capacity to resist and change exploitative and dominating linguistic practices, and it' s an issue of importance to everyone with a concem and interest in the problems of our contemporary society. With such awareness, people can get a more incisive recogni-tion and judgment of the political implications, and correctly acquire new trends in politics and developnient of current affairs.
文摘Objective:This paper aims to investigate the value of individualized care for critically ill patients receiving continuous blood purification therapy.Methods:89 cases of critically ill patients who were treated from June 2021 to June 2023 were randomly divided into groups,with individualized care in group A and routine care in group B.The differences in clinical indicators,purification effect,quality of life,and complications of blood purification were compared between the groups.Results:Heart rate,respiration,body temperature,and other indicators in group A were better than those in group B,P<0.05.C-reactive protein(CRP),β2-microglobulin(β2-MG),blood urea nitrogen(BUN),and phosphorus(P)in group A were lower than those in group B,P<0.05.Group A had higher quality of life than Group B,P<0.05.The complication rate of blood purification in Group A was lower than that in Group B,P<0.05.Conclusion:During continuous blood purification in critically ill patients,individualized nursing intervention can enhance the effect of blood purification,improve the physiological indicators of patients,and reduce the complications of blood purification,which is highly effective and feasible.