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Evaluation of correlation between PM2.5 and radon-progeny equilibrium factor in radon chamber 被引量:4
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作者 Li-Fan Li Rui Chen +1 位作者 Shu-Min Zhou Bin Tang 《Nuclear Science and Techniques》 SCIE CAS CSCD 2018年第10期261-267,共7页
The dosage of environmental radon progeny is typically estimated according to the environmental radon exposure and the recommended radon-progeny equilibrium factor, F. To investigate the relationship between PM2.5 and... The dosage of environmental radon progeny is typically estimated according to the environmental radon exposure and the recommended radon-progeny equilibrium factor, F. To investigate the relationship between PM2.5 and the radon-progeny equilibrium factor, cigarettes are used to simulate the haze–fog in a multi-functional radon chamber to achieve a stable radon concentration environment. A radon detector and a portable laser aerosol spectrometer are used to obtain the values for C_(mean) PM2.5,C_(Rn), and C_p. The results show that the mean values of F conform with the typical value recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation and are within the reasonable range of0.1–0.9. In this study, a positive correlation is observed between the F values and PM2.5 concentrations. 展开更多
关键词 PM2.5 RADON CHAMBER equilibrium factor Linear regression
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Equilibrium and kinetic Si isotope fractionation factors and their implications for Si isotope distributions in the Earth's surface environments 被引量:3
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作者 Hong-tao He Siting Zhang +1 位作者 Chen Zhu Yun Liu 《Acta Geochimica》 EI CAS CSCD 2016年第1期15-24,共10页
Several important equilibrium Si isotope fractionation factors among minerals,organic molecules and the H_4SiO_4 solution are complemented to facilitate the explanation of the distributions of Si isotopes in Earth'... Several important equilibrium Si isotope fractionation factors among minerals,organic molecules and the H_4SiO_4 solution are complemented to facilitate the explanation of the distributions of Si isotopes in Earth's surface environments.The results reveal that,in comparison to aqueous H_4SiO_4,heavy Si isotopes will be significantly enriched in secondary silicate minerals.On the contrary,quadra-coordinated organosilicon complexes are enriched in light silicon isotope relative to the solution.The extent of ^(28)Si-enrichment in hyper-coordinated organosilicon complexes was found to be the largest.In addition,the large kinetic isotope effect associated with the polymerization of monosilicic acid and dimer was calculated,and the results support the previous statement that highly ^(28)Sienrichment in the formation of amorphous quartz precursor contributes to the discrepancy between theoretical calculations and field observations.With the equilibrium Si isotope fractionation factors provided here,Si isotope distributions in many of Earth's surface systems can be explained.For example,the change of bulk soil δ^(30)Si can be predicted as a concave pattern with respect to the weathering degree,with the minimum value where allophane completely dissolves and the total amount of sesquioxides and poorly crystalline minerals reaches their maximum.When,under equilibrium conditions,the well-crystallized clays start to precipitate from the pore solutions,the bulk soil δ^(30)Si will increase again and reach a constant value.Similarly,the precipitation of crystalline smectite and the dissolution of poorly crystalline kaolinite may explain the δ^(30)Si variations in the ground water profile.The equilibrium Si isotope fractionations among the quadracoordinated organosilicon complexes and the H_4SiO_4solution may also shed light on the Si isotope distributions in the Si-accumulating plants. 展开更多
关键词 Si isotopes equilibrium fractionation factor Quantum chemistry calculation Cluster model Kinetic isotope effect
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Deep learning approaches to recover the plasma current density profile from the safety factor based on Grad–Shafranov solutions across multiple tokamaks
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作者 张瀚予 周利娜 +6 位作者 刘钺强 郝广周 王硕 杨旭 苗雨田 段萍 陈龙 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第5期17-28,共12页
Many magnetohydrodynamic stability analyses require generation of a set of equilibria with a fixed safety factor q-profile while varying other plasma parameters.A neural network(NN)-based approach is investigated that... Many magnetohydrodynamic stability analyses require generation of a set of equilibria with a fixed safety factor q-profile while varying other plasma parameters.A neural network(NN)-based approach is investigated that facilitates such a process.Both multilayer perceptron(MLP)-based NN and convolutional neural network(CNN)models are trained to map the q-profile to the plasma current density J-profile,and vice versa,while satisfying the Grad–Shafranov radial force balance constraint.When the initial target models are trained,using a database of semianalytically constructed numerical equilibria,an initial CNN with one convolutional layer is found to perform better than an initial MLP model.In particular,a trained initial CNN model can also predict the q-or J-profile for experimental tokamak equilibria.The performance of both initial target models is further improved by fine-tuning the training database,i.e.by adding realistic experimental equilibria with Gaussian noise.The fine-tuned target models,referred to as fine-tuned MLP and fine-tuned CNN,well reproduce the target q-or J-profile across multiple tokamak devices.As an important application,these NN-based equilibrium profile convertors can be utilized to provide a good initial guess for iterative equilibrium solvers,where the desired input quantity is the safety factor instead of the plasma current density. 展开更多
关键词 plasma equilibrium deep learning safety factor profile current density profile TOKAMAK
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Probabilistic Analysis of Slope Using Finite Element Approach and Limit Equilibrium Approach around Amalpata Landslide of West Central, Nepal
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作者 Mahendra Acharya Khomendra Bhandari +2 位作者 Sandesh Dhakal Aasish Giri Prabin Kafle 《International Journal of Geosciences》 CAS 2024年第5期416-432,共17页
The stability study of the ongoing and recurring Amalpata landslide in Baglung in Nepal’s Gandaki Province is presented in this research. The impacted slope is around 200 meters high, with two terraces that have diff... The stability study of the ongoing and recurring Amalpata landslide in Baglung in Nepal’s Gandaki Province is presented in this research. The impacted slope is around 200 meters high, with two terraces that have different slope inclinations. The lower bench, located above the basement, consistently fails and sets others up for failure. The fluctuating water level of the slope, which travels down the slope masses, exacerbates the slide problem. The majority of these rocks are Amalpata landslide area experiences several structural disruptions. The area’s stability must be evaluated in order to prevent and control more harm from occurring to the nearby agricultural land and people living along the slope. The slopes’ failures increase the damages of house existing in nearby area and the erosion of the slope. Two modeling techniques the finite element approach and the limit equilibrium method were used to simulate the slope. The findings show that, in every case, the terrace above the basement is where the majority of the stress is concentrated, with a safety factor of near unity. Using probabilistic slope stability analysis, the failure probability was predicted to be between 98.90% and 100%. 展开更多
关键词 Finite Element Approach Limit equilibrium Method SLOPE factor of Safety
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Limit equilibrium analysis for stability of soil nailed slope and optimum design of soil nailing parameters 被引量:5
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作者 DENG Dong-ping LI Liang ZHAO Lian-heng 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第11期2496-2503,共8页
Reinforcement of slopes using soil nailing can effectively improve slope stability, and it has been widely used in upgrading cut slopes. Based on the assumptions of stresses on the slip surface, a new method for analy... Reinforcement of slopes using soil nailing can effectively improve slope stability, and it has been widely used in upgrading cut slopes. Based on the assumptions of stresses on the slip surface, a new method for analyzing the stability of a slope reinforced with soil nails was established in the limit equilibrium theory framework, by considering that slope sliding occurs owing to shear failure of the slip surface, which subjects to Mohr–Coulomb(M–C) strength criterion. Meanwhile, in order to easily analyze the stability of a soil nailed slope in actual engineering and facilitate optimum design of parameters for soil nailing, factor of safety(FOS) contour curve charts were drawn on the basis of the established linear proportional relationship between the spacing of soil nails and slope height, and the length of soil nails and slope height. Then, by analyzing and verifying the results obtained from classic examples, some conclusions can be got as follows: 1) The results obtained from the current method are close to those obtained from the traditional limit equilibrium methods, and the current method can provide a strict solution for the slope FOS as it satisfies all the static equilibrium conditions of a sliding body, thus confirming the feasibility of the current method; 2) The slope FOS contour curve charts can be used not only to reliably analyze the stability of a soil nailed slope, but also to design optimally the parameters of soil nailing for the slope with a certain safety requirement. 展开更多
关键词 SLOPE STABILITY soil NAILING LIMIT equilibrium factor of safety CONTOUR curve optimum design
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Limit equilibrium analysis for rock slope stability using basic Hoek–Brown strength criterion 被引量:6
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作者 邓东平 赵炼恒 李亮 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第9期2154-2163,共10页
Hoek–Brown(HB)strength criterion can reflect rock’s inherent failure nature,so it is more suitable for analyzing the stability of rock slopes.However,the traditional limit equilibrium methods are at present only sui... Hoek–Brown(HB)strength criterion can reflect rock’s inherent failure nature,so it is more suitable for analyzing the stability of rock slopes.However,the traditional limit equilibrium methods are at present only suitable for analyzing the rock slope stability using the linear equivalent Mohr–Coulomb(EMC)strength parameters instead of the nonlinear HB strength criterion.Therefore,a new method derived to analyze directly the rock slope stability using the nonlinear HB strength criterion for arbitrary curve slip surface was described in the limit equilibrium framework.The current method was established based on certain assumptions concerning the stresses on the slip surface through amending the initial normal stressσ0 obtained without considering the effect of inter-slice forces,and it can satisfy all static equilibrium conditions of the sliding body,so the current method can obtain the reasonable and strict factor of safety(FOS)solutions.Compared with the results of other methods in some examples,the feasibility of the current method was verified.Meanwhile,the parametric analysis shows that the slope angleβhas an important influence on the difference of the results obtained using the nonlinear HB strength criterion and its linear EMC strength parameters.Forβ≤45°,both of the results are similar,showing the traditional limit equilibrium methods using the linear EMC strength parameters and the current method are all suitable to analyze rock slope stability,but forβ>60°,the differences of both the results are obvious,showing the actual slope stability state can not be reflected in the traditional limit equilibrium methods,and then the current method should be used. 展开更多
关键词 Hoek-Brown strength criterion linear equivalent Mohr-Coulomb strength parameters slope stability limit equilibrium slip surface factor of safety
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A Method Combining Numerical Analysis and Limit Equilibrium Theory to Determine Potential Slip Surfaces in Soil Slopes 被引量:6
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作者 XIAO Shiguo YAN Liping CHENG Zhiqiang 《Journal of Mountain Science》 SCIE CSCD 2011年第5期718-727,共10页
This paper describes a precise method combining numerical analysis and limit equilibrium theory to determine potential slip surfaces in soil slopes. In this method, the direction of the critical slip surface at any po... This paper describes a precise method combining numerical analysis and limit equilibrium theory to determine potential slip surfaces in soil slopes. In this method, the direction of the critical slip surface at any point in a slope is determined using the Coulomb’s strength principle and the extremum principle based on the ratio of the shear strength to the shear stress at that point. The ratio, which is considered as an analysis index, can be computed once the stress field of the soil slope is obtained. The critical slip direction at any point in the slope must be the tangential direction of a potential slip surface passing through the point. Therefore, starting from a point on the top of the slope surface or on the horizontal segment outside the slope toe, the increment with a small distance into the slope is used to choose another point and the corresponding slip direction at the point is computed. Connecting all the points used in the computation forms a potential slip surface exiting at the starting point. Then the factor of safety for any potential slip surface can be computed using limit equilibrium method like Spencer method. After factors of safety for all the potential slip surfaces are obtained, the minimum one is the factor of safety for the slope and the corresponding potential slip surface is the critical slip surface of the slope. The proposed method does not need to pre-assume the shape of potential slip surfaces. Thus it is suitable for any shape of slip surfaces. Moreover the method is very simple to be applied. Examples are presented in this paper to illustrate the feasibility of the proposed method programmed in ANSYS software by macro commands. 展开更多
关键词 Soil slope Stress field Potential slip surface Slope stability factor of safety Numerical analysis Limit equilibrium method ANSYS software
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Limit equilibrium method for slope stability based on assumed stress on slip surface 被引量:2
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作者 邓东平 赵炼恒 李亮 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第11期2972-2983,共12页
In the limit equilibrium framework, two- and three-dimensional slope stabilities can be solved according to the overall force and moment equilibrium conditions of a sliding body. In this work, based on Mohr-Coulomb(M-... In the limit equilibrium framework, two- and three-dimensional slope stabilities can be solved according to the overall force and moment equilibrium conditions of a sliding body. In this work, based on Mohr-Coulomb(M-C) strength criterion and the initial normal stress without considering the inter-slice(or inter-column) forces, the normal and shear stresses on the slip surface are assumed using some dimensionless variables, and these variables have the same numbers with the force and moment equilibrium equations of a sliding body to establish easily the linear equation groups for solving them. After these variables are determined, the normal stresses, shear stresses, and slope safety factor are also obtained using the stresses assumptions and M-C strength criterion. In the case of a three-dimensional slope stability analysis, three calculation methods, namely, a non-strict method, quasi-strict method, and strict method, can be obtained by satisfying different force and moment equilibrium conditions. Results of the comparison in the classic two- and three-dimensional slope examples show that the slope safety factors calculated using the current method and the other limit equilibrium methods are approximately equal to each other, indicating the feasibility of the current method; further, the following conclusions are obtained: 1) The current method better amends the initial normal and shear stresses acting on the slip surface, and has the identical results with using simplified Bishop method, Spencer method, and Morgenstern-Price(M-P) method; however, the stress curve of the current method is smoother than that obtained using the three abovementioned methods. 2) The current method is suitable for analyzing the two- and three-dimensional slope stability. 3) In the three-dimensional asymmetric sliding body, the non-strict method yields safer solutions, and the results of the quasi-strict method are relatively reasonable and close to those of the strict method, indicating that the quasi-strict method can be used to obtain a reliable slope safety factor. 展开更多
关键词 two-dimensional slope three-dimensional slope limit equilibrium analysis normal stress shear stress safety factor
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Limit equilibrium stability analysis of slopes under external loads 被引量:4
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作者 DENG Dong-ping ZHAO Lian-heng LI Liang 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第9期2382-2396,共15页
Two calculation modes for the effect of external load on slope stability, i.e., mode I in which the external load is thought to act on slope surface, and mode II in which the external load is thought to act on slip su... Two calculation modes for the effect of external load on slope stability, i.e., mode I in which the external load is thought to act on slope surface, and mode II in which the external load is thought to act on slip surface along the force action line, were considered. Meanwhile, four basic distribution patterns of external load were used, of which complex external loads could be composed. In analysis process, several limit equilibrium methods, such as Swedish method, simplified Bishop method, simplified Janbu method, Spencer method, Morgenstern-Price(M-P) method, Sarma method, and unbalanced thrust method, were also adopted to contrast their differences in slope stability under the external load. According to parametric analysis, some conclusions can be obtained as follows:(1) The external load, with the large magnitude, small inclination angle, and acting position close to the slope toe,has more positive effect on slope stability;(2) The results calculated using modes I and II of external load are similar, indicating that the calculation mode of external load has little influence on slope stability;(3) If different patterns of external loads are equivalent to each other, their slope stability under these external loads are the same, and if not, the external load leads to the better slope stability,as action position of the resultant force for external load is closer to the lower sliding point of slip surface. 展开更多
关键词 slope stability calculation mode of external load distribution pattern of external load limit equilibrium slip surface factor of safety (FOS)
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Comparative Study of Slope Soils Analysis by Using Limit Equilibrium and Finite Element Methods
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作者 Kempena Adolphe Watha Ndoudy Noël +4 位作者 Obami Ondon Harmel Mbilou Urbain Gampio Antonio Olimpio Gonçalves Rafael Guardado Lacaba Boudzoumou Florent 《International Journal of Geosciences》 CAS 2022年第12期1089-1102,共14页
The slope soil analysis remains a corporate concern in construction activities. Because of its significance, the evaluation of slope soil stability has called widespread attention to several researchers all over the w... The slope soil analysis remains a corporate concern in construction activities. Because of its significance, the evaluation of slope soil stability has called widespread attention to several researchers all over the world. Many methods have been technologically advanced to evaluate the stability of slopes soils founded on distinct expectations and circumstances. Every method has specific benefits and limits. This work makes a comparison among safety factors and slip surfaces of slopes soils based on using Limit Equilibrium and Finite Element methods. Therefore, SLIDE 6.0 and PLAXIS 8.0 software were used for Limit Equilibrium and Finite Element methods, respectively. The computations of safety factors were performed for diverse shapes of slopes including different types of soils. Failure surfaces and values of safety factors obtained were compared for both methods used. It was noticed that the safety factors obtained from Limit Equilibrium methods were larger than of which is obtained by the finite element code. Moreover, an important change is noticed between the slip surfaces obtained by using both approaches. 展开更多
关键词 Slopes Soils Slip Surface Limit equilibrium Finite Element factor of Safety
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EFFECT OF ALLOY ELEMENTS ON QUASIEQUILIBRIUM MICROSTRUCTURE IN Fe-Mn-Ni-Cr STEELS
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作者 XIE Changsheng SUN Peizhen ZHAO Jiansheng CHEN Yuqiu Huazhong University of Science and Technology,Wuhan,China XIE Changsheng Associate Professor,Department of Mechanical Engineering No.2,Huazhong University of Science and Technology,Wuhan 430074,China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1990年第1期52-57,共6页
The microstructures of Fe-Mn-Ni-Cr steels with medium carbon and the effect of alloy ele- ments on them have been investigated by means of X-ray diffraction quantitative phase ana- lyses,metallography and hardness tes... The microstructures of Fe-Mn-Ni-Cr steels with medium carbon and the effect of alloy ele- ments on them have been investigated by means of X-ray diffraction quantitative phase ana- lyses,metallography and hardness tests.The volume fraction of martensite in steels quenched at 1100℃ can be expressed as: f_M^(1100)=162.643-15.482Mn-7.36Ni-4.286(Cr+Mo+V) Based on this expression,the quasi-equilibrium microstructure diagram has been obtained.It is shown that the effect of Mn on the austenite stability is greater than that of Ni.The equiva- lent [Ni]=2.104Mn+Ni and equivalent [Cr]=Cr+Mo+V. The driving force for martensite transformation at M_s point has been calculated to he drastically decreased by element Mn. 展开更多
关键词 quasi-equilibrium microstructure diagram martensitic transformation driving force multi-factor regression analysis
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超深基坑吊脚桩局部稳定性分析
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作者 孙昌利 陈富强 +1 位作者 李支令 贾恺 《长江科学院院报》 CSCD 北大核心 2024年第10期133-139,共7页
目前基坑设计中对于吊脚桩预留岩肩的宽度和支护桩的嵌固深度取值大多从对上部支护结构内力及变形的影响角度出发,往往忽略了支护结构底部附近的局部稳定性问题。依托珠江三角洲水资源配置工程超深竖井项目,提出了外倾结构面下或破碎岩... 目前基坑设计中对于吊脚桩预留岩肩的宽度和支护桩的嵌固深度取值大多从对上部支护结构内力及变形的影响角度出发,往往忽略了支护结构底部附近的局部稳定性问题。依托珠江三角洲水资源配置工程超深竖井项目,提出了外倾结构面下或破碎岩体吊脚桩基坑可能存在的3种破坏模式,采用极限平衡法分别给出了不同破坏模式下稳定安全系数的计算方法。同时针对不同破坏模式下,影响稳定安全系数的参数如岩层的埋深、结构面的倾角和力学参数、岩肩宽度、岩肩深度等进行了分析,结果表明外倾结构面倾角、结构面或岩体的力学参数对稳定安全系数影响较大。研究成果可为类似工程提供参考。 展开更多
关键词 深基坑 竖井 吊脚桩 结构面 极限平衡法 安全系数
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基于DSGE模型的科技信贷激励政策研究
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作者 王慧 王子晗 刘微 《经济问题》 CSSCI 北大核心 2024年第8期85-94,共10页
通过构建基于全要素生产率厂商异质性的NK-DSGE(新凯恩斯—动态随机一般均衡)模型,模拟科技信贷激励政策的传导机制与政策效果,研究发现政策效果从大到小依次是常规货币政策、政府部门贴息、中央银行再贷款利率、中央银行定向降准、中... 通过构建基于全要素生产率厂商异质性的NK-DSGE(新凯恩斯—动态随机一般均衡)模型,模拟科技信贷激励政策的传导机制与政策效果,研究发现政策效果从大到小依次是常规货币政策、政府部门贴息、中央银行再贷款利率、中央银行定向降准、中央银行再贷款抵押率,与我国科技信贷激励政策的实践效果相吻合。进一步研究发现,政府贴息、再贷款利率的外生冲击波动幅度对政策效果影响弹性更大。建议地方政府应和银行加强联动,完善科技信贷风险补偿机制、贷款担保体系;另外,中国人民人行应加强常规货币政策实施精准性,并探索更加灵活的结构型货币政策机制。 展开更多
关键词 科技信贷政策 动态随机一般均衡模型 全要素生产率 厂商异质性
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基于PR—Henry改进模型的酸性天然气——地层水体系及其相平衡特征分析
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作者 杨宇 王建猛 +3 位作者 张骞 刘建国 刘荣和 江良伟 《天然气工业》 EI CAS CSCD 北大核心 2024年第6期64-73,共10页
准确表征酸性天然气—地层水体系的相平衡规律,对于天然气开发过程中的水溶气量和凝析水量分析具有重要意义,但目前常用的PR状态方程与Henry定律等理论对酸性天然气—地层水体系的相平衡研究还存在不适用的问题。为进一步考虑酸性气体... 准确表征酸性天然气—地层水体系的相平衡规律,对于天然气开发过程中的水溶气量和凝析水量分析具有重要意义,但目前常用的PR状态方程与Henry定律等理论对酸性天然气—地层水体系的相平衡研究还存在不适用的问题。为进一步考虑酸性气体和地层水矿化度对体系相平衡的影响,改进并提高对天然气溶解度和饱和含水量的计算精度,在PR状态方程与Henry定律相结合建立的PR—Henry模型基础上,考虑了溶解盐对体系相平衡的影响,采用定标粒子理论(SPT)修正了Henry常数,建立了改进的PR—Henry模型,最后分析了天然气组成、压力、温度和盐水含盐量对天然气溶解量和饱和含水量的影响。研究结果表明:(1)模型计算结果与实测资料对比,平均相对偏差分别为5.3%和4.55%,表明该模型能够应用于不同温度、压力和组成的酸性天然气-地层水体系的相平衡计算;(2)天然气在地层水中的溶解量受天然气组成、温度、压力和地层水含盐量的影响;(3)天然气饱和含水量受温度和压力影响十分明显。结论认为,改进的PR—Henry模型为天然气开采过程评价和CO_(2)埋存溶解量计算提供了一种有效的方法,对于评估天然气可采储量及开发特征具有重要的参考意义。 展开更多
关键词 酸性天然气 相平衡计算 PR—Henry模型 定标粒子理论 影响因素
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某钼(铜)多金属矿排土场边坡稳定性分析
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作者 刘智权 《世界有色金属》 2024年第18期127-129,共3页
为了研究排土场边坡稳定性,以西藏天仁矿业有限公司邦铺矿区钼(铜)多金属矿排土场为研究对象。通过工程地质条件调研,并考虑自然工况、降雨工况、地震工况三种工况,最后采用极限平衡分析法中的简化Bishop法、Spencer法与Morgenstern-Pri... 为了研究排土场边坡稳定性,以西藏天仁矿业有限公司邦铺矿区钼(铜)多金属矿排土场为研究对象。通过工程地质条件调研,并考虑自然工况、降雨工况、地震工况三种工况,最后采用极限平衡分析法中的简化Bishop法、Spencer法与Morgenstern-Prince法对该矿排土场边坡稳定性进行分析。结果表明:排土场1-1’剖面在自然工况、降雨工况及地震工况下以极限平衡法计算所得到的安全系数均大于规范值,据此排土场边坡处于稳定状态。研究结果对该矿其他排土场边坡稳定性分析提供一定的参考依据。 展开更多
关键词 排土场边坡 稳定性分析 不同工况 安全系数 极限平衡分析法
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一种小体积氡子体气溶胶调控装置的研制
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作者 邓天羽 单健 +3 位作者 蔡祥鸣 李灏璇 李鸿亮 曾旭威 《核技术》 EI CAS CSCD 北大核心 2024年第10期88-97,共10页
为了满足国内外放射性气溶胶监测仪的氡子体气溶胶干扰量有效性校准的需求,基于气溶胶粒子与氡及其子体的行为规律,研制了小体积氡子体气溶胶调控装置,该装置包括气溶胶稀释回路、氡子体调控回路和可编程逻辑控制器(Programmable Logic ... 为了满足国内外放射性气溶胶监测仪的氡子体气溶胶干扰量有效性校准的需求,基于气溶胶粒子与氡及其子体的行为规律,研制了小体积氡子体气溶胶调控装置,该装置包括气溶胶稀释回路、氡子体调控回路和可编程逻辑控制器(Programmable Logic Controller,PLC)控制系统的总控箱三部分,通过调控装置内的氡浓度、气溶胶粒子数浓度与换气率,能够输出氡子体状态参数稳定的氡子体气溶胶。实验结果表明,该小体积氡子体气溶胶调控装置可以实现的平衡当量浓度稳定调控范围为:3.3×10^(2)~9.4×10^(3) Bq·m^(-3),平衡因子的稳定调控范围为:0.12~0.58,未结合态份额的稳定调控范围为:1.4%~62.7%。在4 h内可以保证平衡当量氡浓度的变化范围在10%以内,均匀性实验相对标准偏差小于7%。氡子体关键参数的调控范围宽泛、氡子体空间分布的均匀性与稳定性较好,可以有效模拟现场测量环境,达到了装置的研制目的。 展开更多
关键词 氡子体气溶胶 平衡因子 未结合态份额
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接驳轨道交通的共享单车潮汐均衡时空分布模式
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作者 王涵菁 邬群勇 +3 位作者 邝嘉恒 郑汉捷 张晨 尹延中 《福州大学学报(自然科学版)》 CAS 北大核心 2024年第2期176-183,共8页
以深圳市为研究区,使用工作日早高峰的接驳骑行订单数据,考虑地铁站和出入口两层面的潮汐均衡性分类,从单车调度角度将出入口划分为无需调度型、站内调度型和站外调度型;使用非负矩阵分解方法划分出入口流量时空分布类别,确定调度时间.... 以深圳市为研究区,使用工作日早高峰的接驳骑行订单数据,考虑地铁站和出入口两层面的潮汐均衡性分类,从单车调度角度将出入口划分为无需调度型、站内调度型和站外调度型;使用非负矩阵分解方法划分出入口流量时空分布类别,确定调度时间.结果表明,将接驳轨道交通的潮汐均衡分析聚焦到出入口层面,精确划分出入口调度类型,可确定调度方式和产生调度需求的时间,为单车管理者进行车辆调度提供可靠的数据支持. 展开更多
关键词 潮汐均衡性 共享单车 接驳 地铁出入口 非负矩阵分解
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基于多因素均衡动态分簇的WSN路由协议算法
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作者 朱本科 高丙朋 蔡鑫 《科学技术与工程》 北大核心 2024年第16期6799-6808,共10页
为了解决无线传感器网络分簇路由协议随机筛选簇头节点的位置分布不均衡及转发节点的数据传输路径不合理会加剧节点能量消耗、缩短网络生存周期的问题,提出一种基于改进社交网络搜索(improved social network search, ISNS)算法优化模糊... 为了解决无线传感器网络分簇路由协议随机筛选簇头节点的位置分布不均衡及转发节点的数据传输路径不合理会加剧节点能量消耗、缩短网络生存周期的问题,提出一种基于改进社交网络搜索(improved social network search, ISNS)算法优化模糊C均值聚类(fuzzy C-means, FCM)的多因素均衡动态分簇路由协议(multi-factor balanced dynamic clustering routing protocol, MD-LEACH)。首先,引入莱维飞行改进反向精英学习策略,以增强社交网络搜索算法的全局寻优能力;接着,使用ISNS优化模糊C均值聚类算法对网络节点动态均匀分簇,均衡网络负载;此外,在每个簇内,考虑簇内节点的能量因素和位置因素引入模糊推理,设计两种簇头选取模式,动态选举簇首,提高簇首质量。在稳定传输阶段,将单跳改为簇首之间的通信的方式,使用改进的蚁群算法寻找最优数据传输路径,提高能量效率。仿真结果表明,算法能够有效提高能量效率,平衡网络负载,延长网络生存期。 展开更多
关键词 改进社交网络搜索(ISNS)算法 模糊C均值聚类(FCM) 莱维飞行 多因素均衡 动态分簇 模糊推理
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过敏性紫癜患儿血清miR-125b、HIF-1α表达水平及其与Th1/Th2平衡的关系 被引量:1
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作者 彭文娟 刘京涛 +2 位作者 李婉莹 段艳霞 谷肖灵 《海南医学》 CAS 2024年第3期376-380,共5页
目的检测过敏性紫癜患儿血清microRNA-125b(miR-125b)、缺氧诱导因子-1α(HIF-1α)表达水平,并探讨其与辅助性T细胞1(Th1)/辅助性T细胞2(Th2)(Th1/Th2)平衡的关系。方法选择2021年5月至2022年12月三门峡市中心医院收治的94例过敏性紫癜... 目的检测过敏性紫癜患儿血清microRNA-125b(miR-125b)、缺氧诱导因子-1α(HIF-1α)表达水平,并探讨其与辅助性T细胞1(Th1)/辅助性T细胞2(Th2)(Th1/Th2)平衡的关系。方法选择2021年5月至2022年12月三门峡市中心医院收治的94例过敏性紫癜患儿作为研究组,另选择同期在我院体检的88例健康儿童作为对照组。所有受检者入院后均采用实时荧光定量PCR(qRT-PCR)法检测外周血miR-125b水平,采用酶联免疫吸附试验检测血清HIF-1α、IFN-γ、IL-4水平,利用流式细胞仪检测Th1、Th2细胞水平并计算Th1/Th2比值。采用Pearson相关分析探讨过敏性紫癜患儿血清miR-125b、HIF-1α表达水平与Th1/Th2比值的关系,采用受试者工作特征曲线(ROC)评估血清miR-125b、HIF-1α表达水平对过敏性紫癜发生的预测价值。结果研究组患者的血清miR-125b、HIF-1α及外Th2细胞水平分别为(0.80±0.18)、(122.54±20.54)pg/L、(7.04±1.57),明显高于对照组的(0.38±0.11)、(48.58±8.99)pg/L、(4.22±0.55),Th1细胞水平、Th1/Th2比值分别为(7.55±1.66)、(1.07±0.11),明显低于对照组的(12.01±2.80)、(2.85±0.58),差异均有统计学意义(P<0.05);研究组患者的血清IFN-γ水平为(19.28±2.66)pg/mL,明显低于对照组的(26.64±3.41)pg/mL,血清IL-4水平为(28.44±3.87)ng/L,明显高于对照组的(17.66±2.99)ng/L,差异均有统计学意义(P<0.05);经Pearson相关分析结果显示,过敏性紫癜患儿血清miR-125b与IFN-γ、Th1/Th2比值均呈负相关(r=-0.447、-0.516,P<0.05),与IL-4呈正相关(r=0.521,P<0.05);血清HIF-1α与IFN-γ、Th1/Th2比值均呈负相关(r=-0.511、-0.445,P<0.05),与IL-4呈正相关(r=0.495,P<0.05);经ROC分析结果显示,血清miR-125b预测小儿过敏性紫癜的曲线下面积(AUC)为0.841,敏感度、特异度分别为90.01%、64.41%;HIF-1α预测小儿过敏性紫癜的AUC为0.764,敏感度、特异度分别为90.02%、58.78%;两者联合预测小儿过敏性紫癜的AUC为0.910,敏感度、特异度为88.74%、87.19%。结论过敏性紫癜患儿血清miR-125b、HIF-1α表达水平均升高,且两者与Th1/Th2比值呈负相关,两者可通过调节Th1/Th2、介导炎症反应参与疾病发展,有望作为预测小儿过敏性紫癜发病的有效指标。 展开更多
关键词 过敏性紫癜 microRNA-125b 缺氧诱导因子-1Α TH1/TH2平衡 相关性
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湖北省2019-2021年岩溶碳汇估算及其驱动因子分析 被引量:1
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作者 王懿洁 马传明 +3 位作者 郭静 党慧慧 黄鹏 范威 《地质科技通报》 CAS CSCD 北大核心 2024年第2期330-343,共14页
碳酸盐岩在水循环过程中的碳汇效应显著,加之岩溶地貌在我国分布广泛,所以探求岩溶碳汇潜力的研究对制定区域增汇策略具有重要意义。选取位于西南岩溶区的湖北省为重点研究区域,基于水化学径流法及入渗-平衡化学法进行定量化计算和比较... 碳酸盐岩在水循环过程中的碳汇效应显著,加之岩溶地貌在我国分布广泛,所以探求岩溶碳汇潜力的研究对制定区域增汇策略具有重要意义。选取位于西南岩溶区的湖北省为重点研究区域,基于水化学径流法及入渗-平衡化学法进行定量化计算和比较,利用ArcGIS空间分析技术整体评估湖北省2019-2021年岩溶碳汇的空间格局与量级,探索更适宜应用于区域尺度的岩溶作用碳汇估算方法,综合分析岩溶碳汇的驱动因子,发掘更大的增汇潜力。研究结果表明:(1)采用入渗-平衡化学法估算3 a碳汇强度大小为2020年>2019年>2021年,丰水年(2020年)岩溶碳汇总量约为枯水年(2019年)的6倍,3 a年均碳汇强度为12.84 t/(km^(2)·a),碳汇总量达163.89×10^(4) t/a;(2)相较于水化学径流法,入渗-平衡化学法计算结果更为准确,获取数据资料较为简单,大小空间尺度都具有一定的普适性;(3)碳汇作用变化是高度动态的,气候变化下变化幅度主要由径流深决定,碳汇强度随径流深增大而变强,土地利用类型调控着岩溶作用碳汇强度;(4)鄂西南地区岩溶作用强烈,可建立岩溶碳汇试验区,定量评估人工干预所带来的增汇效果。研究结果不仅提供了精确易行的岩溶碳汇估算方法,而且确定了湖北省岩溶碳汇的量级与空间格局,摸清了碳汇强度驱动因子的共同耦合作用,体现了岩溶碳汇的人为可调控性以及复杂性,进一步为环境保护政策、人工增汇措施的制定提供了可靠的科学依据。 展开更多
关键词 岩溶碳汇 水化学径流法 入渗-平衡化学法 ArcGIS空间分析 驱动因子 湖北省
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