Evaluation of correlation between PM2.5 and radon-progeny equilibrium factor in radon chamber

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.

Equilibrium and kinetic Si isotope fractionation factors and their implications for Si isotope distributions in the Earth's surface environments

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.

Probabilistic Analysis of Slope Using Finite Element Approach and Limit Equilibrium Approach around Amalpata Landslide of West Central, Nepal

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%.

Limit equilibrium analysis for stability of soil nailed slope and optimum design of soil nailing parameters

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.

Comparative Study of Slope Soils Analysis by Using Limit Equilibrium and Finite Element Methods

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.

基于DSGE模型的科技信贷激励政策研究

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。

Evaluation of Ecological Sustainable Development in the Yangtze River Delta Region Based on Ecological Footprint Theory

The ecological footprint was employed as a quantitative indicator of resource inputs,enabling a detailed account of the structure of biological resources and energy occupancy,as well as the variation of resource productivity in the Yangtze River Delta(YRD)Region.From 2004 to 2018,there were notable variations in the ecological productivity of different types of land on basis of China’s equilibrium factor across the three provinces and one city in the YRD region.Jiangsu Province exhibited the highest ecological productivity of arable land,while Anhui Province exhibited the highest ecological productivity of forest land.Shanghai City exhibited the highest ecological productivity of pasture land,while Zhejiang Province exhibited the highest ecological productivity of water area.In 2018,the proportion of arable land within the total ecological carrying capacity of the YRD region reached 74.35%.Furthermore,the contribution of Jiangsu and Anhui provinces to the YRD’s total ecological carrying capacity was 41.36%and 41.26%,respectively.In the construction of a new development pattern in the YRD region,which is dominated by the domestic cycle as the main body and mutually reinforced by domestic and international double-cycle,the YRD region should combine the utilization of natural forces with innovation in science,technology and cooperation mechanisms.Furthermore,the government should guide the concentration of social capital towards green industries.It is also recommended that the moderate reduction of ecological footprints should be encouraged,and that the security of biological resources and energy,the leadership in the field of cutting-edge science and technology should be ensured in YRD region.This will facilitate the formation of a new development pattern of higher-quality integration at the national level firstly.

超深基坑吊脚桩局部稳定性分析

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。

EFFECT OF ALLOY ELEMENTS ON QUASIEQUILIBRIUM MICROSTRUCTURE IN Fe-Mn-Ni-Cr STEELS

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.

某钼(铜)多金属矿排土场边坡稳定性分析

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。

一种小体积氡子体气溶胶调控装置的研制

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。

基于Geo-Slope数值模拟的某石灰石矿边坡稳定性分析

随着露天矿山边坡安全滑坡事件频发,矿山企业对边坡安全越发重视。以某石灰石矿超过100 m的边坡为研究对象,通过分析该矿区的工程地质、水文地质条件,从中选择3个典型剖面,通过赤平投影方式分析其破坏模式,结合室内试验和数值分析的方法进行渗流场分析和安全系数算。结果表明,3个典型剖面最小安全系数均满足规范要求,均达到稳定状态。随着矿山开采深度的延伸,边坡高度越来越高,需要加强对边坡监测及安全管理工作。

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

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。

压缩空气储能地下内衬硐库上覆岩体稳定性分析

地下内衬硐库是压缩空气蓄能电站储气装置的主要方案,鉴于其高内气压的荷载特征,硐库上覆岩体稳定性评价是工程设计的关键环节之一。针对隧道式储气硐库,基于极限平衡理论和Mohr-Coulomb强度准则,建立了上覆岩体极限状态下被动岩土压力的力学模型,通过应力边界积分建立了三力矩平衡方程组,提出了可计算任意形态破裂面的安全系数求解方法。结果表明,安全系数主要受埋深、硐库半径、储气压力和地应力系数等因素控制,与埋深呈非线性正相关,与储气压力呈非线性负相关,与半径呈非线性负相关。针对Ⅲ级岩体条件下,给出了埋深、硐径和最大储气压力等3个设计参数满足稳定性要求的取值范围,对工程设计具有重要指导意义。

基于多因素均衡动态分簇的WSN路由协议算法

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。

放射性矿山氡及氡子体浓度特征的氡暴露有效剂量估算

氡及氡子体暴露剂量是地下放射性矿山工作人员辐射剂量的主要来源。为了掌握氡及氡子体浓度分布并估算氡暴露剂量,对某放射性矿山井下6个典型场所的氡、结合态和未结合态氡子体浓度和通风情况进行了监测,并确定平衡因子和氡子体未结合态份额,依据氡及氡子体浓度特征参数估算该矿井的典型场所的氡暴露有效剂量;基于估算得到的氡暴露有效剂量、生产要求和通风现状,提出了通风降氡的管理措施以确保矿井生产安全。结果显示:(1)该放射性矿山井下典型场所的平衡因子在0.02~0.29,氡子体未结合态份额在0.034~0.098,平衡因子与氡子体未结合态份额之间存在负相关性。(2)正常生产场所的氡暴露年有效剂量E_(Rn1)和E_(Rn2)分别为0.17~19.70 mSv和0.11~16.52 mSv,均低于20 mSv。

基于极限平衡法与强度折减法的某高寒高海拔矿山边坡稳定性分析

为验证西部高寒高海拔地区某露天矿山设计边坡稳定性是否满足现行规范要求,并分析露天开采导致的位移变化规律,本文参考矿区终了境界平面图选取具有代表性的典型剖面,结合矿区实际情况、工程地质条件、室内物理力学试验,利用H-B准则等,综合确定矿区边坡的岩土体物理力学参数;采用极限平衡法中的不平衡推力法和M-P法及有限差分强度折减法,以安全系数为指标,验证了设计边坡的稳定性。通过极限平衡与强度折减计算结果的对比,验证了强度折减法计算潜在滑动面形态及安全系数的可靠性。在此基础上,分析强度折减前,在岩体开挖、施加爆破及地震荷载下矿山边坡的位移显现规律。研究结果可为露天矿山设计中的边坡稳定性定量分析提供参考。

海南典型温泉设施内空气中氡及氡子体平衡因子测量研究

平衡因子是氡子体所致剂量估算和评价的重要参数。为了解海南省温泉设施内不同空间空气中氡及氡子体平衡因子的水平与分布范围,本文采用连续测量方法对不同地域典型温泉设施内不同空间氡及氡子体浓度、室内温泉泡池加水过程氡及氡子体浓度进行现场测量,计算并分析平衡因子的变化。测量结果表明:平衡因子在较大范围内分布,通风状况是影响平衡因子的重要因素,通风越好,平衡因子越小;室内引入温泉水后,空气中氡及氡子体浓度升高,平衡因子略有上升。

西部某露天高陡矿山边坡稳定性分析及影响因素研究

西部地区矿山资源丰富,地质条件复杂,使得该地区的边坡稳定性分析问题备受关注。本文以西部地区某露天金属矿山边坡为研究对象,根据边坡形态、地层岩性、构造、水文和风化程度等工程地质条件,划分3个边坡分区,每个分区选取1~2条代表性剖面。在现场勘察的基础上,采用室内试验和数值模拟方法开展边坡稳定性分析研究工作。对研究区4种主要岩性开展必要的岩石物理力学试验,采用Hoek-Brown强度折减法用于计算岩体的抗剪强度参数;对研究区地下水作用下的渗流场进行分析,在此基础上采用两种不同的极限平衡分析方法计算边坡稳定性。研究结果表明,在3种不同工况下计算的安全系数均满足规范要求。

含剪切节理面岩质边坡滑裂面位置及稳定性研究

同向双平面滑动是存在单一地质断层面(剪切节理面)岩质边坡的常见破坏模式之一,但对该种类型的滑裂面计算方法并不充足。为了能够更加高效准确地寻找边坡的滑裂面位置,判断边坡的稳定性,基于极限平衡理论和非线性数学规划模型,假设滑体的滑动方式为同向双平面滑动,再假设目标函数为该岩质边坡的安全系数,运用MTALAB全局最优搜索法,计算含剪切节理面工程边坡在天然工况作用下的滑裂面位置及稳定性,并与极限分析法、强度折减法和毕肖普法进行对比分析。研究结果表明:基于极限平衡理论和非线性数学规划模型得出的滑裂面位置与安全系数基本一致,验证此类方法的可行性,为存在单一地质断层面岩质边坡的滑裂面计算和稳定性分析提供了新依据。