THE AVALANCHE DYNAMICS IN RANDOM NEAREST NEIGHBOR MODELS OF EVOLUTION WITH INTERACTION STRENGTH

A generalized Bak-Sneppen model （BS model） of biological evolution with intcraction strength θ is introduced in d-dimensional space, where the “nearest neighbors” are chosen among the 2d neighbors of the extremal site, with the probabilities rebated to the sizes of the fitnesses. Simulations of one- and two-dimensional models arc given.For given θ 〉 0, the model can self-organize, to a critical state, and the critical threshold fc（θ） decreases as θ increases. The exact gap equation depending on θ is presented, which reduces to the gap equation of BS model as θ tends to infinity. An exact cquation for the critical exponent γ（θ） is also obtained. Scaling relations are established among the six critical exponents of the avalanches of the model.

Estimating the properties of weathered bedrock and pile-rock interaction from the geological strength index

The effect of variable rock mass properties on pile-rock interaction poses a great challenge to the design of stabilizing piles and numerical analysis of pile-rock interaction. The paper presents a novel method to estimate the properties of weathered bedrock, which can be applied to routine design of landslide-stabilizing piles for collivial landslides. The Ercengyan landslide located in the Three Gorges Reservoir, China, is the area of interest for this study. A geological investigation and triaxial tests were conducted to estimate the basic parameters, including Geological Strength Index(GSI), uniaxial compressive strength σ_(ci) and Hoek-Brown constant m_i of intact bedrock in the study area. Hoek-Brown criterion was used to estimate mechanical properties of the weathered rock, including elastic modulus E_m, cohesion c, friction angle Φ, and normal ultimate lateral resistance p_(max). A parametric study was performed to evaluate the effect of parameterizations of GSI, σ_(ci) and m_i on the bedrock properties and p-y curves. The estimated rock mass properties were used with PLAXIS 2D software to simulate pile-rock interaction. Effect of GSI on stress at the pile-rock interface and in the rock, pile bending moment, pile shear force, and p-y curve were analysed.

Effect of structural characteristics distribution on strength demand and ductility reduction factor of MDOF systems considering soil-structure interaction

It is known that structural stiffness and strength distributions have an important role in the seismic response of buildings. The effect of using different code-specified lateral load patterns on the seismic performance of fixed-base buildings has been investigated by researchers during the past two decades. However, no investigation has yet been carried out for the case of soil-structure systems. In the present study, through intensive parametric analyses of 21,600 linear and nonlinear MDOF systems and considering five different shear strength and stiffness distribution patterns, including three code-specified patterns as well as uniform and concentric patterns subjected to a group of earthquakes recorded on alluvium and soft soils, the effect of structural characteristics distribution on the strength demand and ductility reduction factor of MDOF fixed-base and soil-structure systems are parametrically investigated. The results of this study show that depending on the level of inelasticity, soil flexibility and number of degrees-of-freedoms (DOFs), structural characteristics distribution can significantly affect the strength demand and ductility reduction factor of MDOF systems. It is also found that at high levels of inelasticity, the ductility reduction factor of low-rise MDOF soil-structure systems could be significantly less than that of fixed-base structures and the reduction is less pronounced as the number of stories increases.

The interaction effect of grip strength and lung function (especially FVC) on cardiovascular diseases: a prospective cohort study in Jiangsu Province, China

OBJECTIVE Lung function and grip strength(GS)are associated with cardiovascular disease(CVD),but whether these risk factors interact to affect CVD is unknown.This study aimed to explore the interactions between lung function and GS with major CVD(defined as fatal/non-fatal myocardial infarction,stroke,and heart failure)incidence.METHODS We conducted a prospective cohort study on the Chinese population in Jiangsu Province.Cox proportional haz-ards models were used to explore the associations between GS,lung function,and major CVD incidence.RESULTS A total of 5967 participants were included in our study;among them,182 participants developed major CVD.Parti-cipants with low forced vital capacity(FVC)had a higher risk of major CVD(hazard ratio(HR)=1.45;95%confidence interval(CI):1.05-2.01;P<0.05)compared with normal FVC.The risk of major CVD incidence(HR=0.54;95%CI:0.35-0.83;P<0.01)was significantly lower in participants with high GS than in individuals with low GS.The interaction between FVC and GS for major CVD incidence(P=0.006)was statistically significant.Compared with normal FVC participants with high GS,low FVC parti-cipants with low GS had the highest risk of major CVD incidence(HR=2.50;95%CI:1.43-4.36;P<0.01).CONCLUSION Among people with low FVC,the risk of major CVD is lower with high GS.Participants with low FVC and low GS have the highest risk of major CVD.Therefore,more attention should be paid to the incidence of major CVD in individu-als with low FVC,especially those who have lower GS.

Effect of Electron Correlation and Breit Interaction on Energies, Oscillator Strengths, and Transition Rates for Low-Lying States of Helium

The transition energies, E1 transitional oscillator strengths of the spin-allowed as well as the spin-forbidden and the corresponding transition rates, and complete M1, E2, M2 forbidden transition rates for 1s^(2), 1s2s, and 1s2p states of He I, are investigated using the multi-configuration Dirac–Hartree–Fock method. In the subsequent relativistic configuration interaction computations, the Breit interaction and the QED effect are considered as perturbation, separately. Our transition energies, oscillator strengths, and transition rates are in good agreement with the experimental and other theoretical results. As a result, the QED effect is not important for helium atoms, however, the effect of the Breit interaction plays a significant role in the transition energies, the oscillator strengths and transition rates.

Dissociation of polar oil components in low salinity water and its impact on crude oil-brine interfacial interactions and physical properties

Despite many efforts into the study of fluids interaction in low salinity water flooding, they are not probing the basics of transport phenomena between the involved phases. This work is aimed to bring new understanding of fluid-fluid interaction during low salinity water flooding through a series of organized experiments in which a crude oil sample with known properties was kept in contact with different brine solutions of various ionic strengths. Measuring brine pH, conductivity and crude oil viscosity and density for a period of 45 days illustrates the strong effect of the contact time and ionic strength on the dissociation of polar components and physical properties of the crude oil and brine. Besides, the interfacial tension(IFT) measurements show that the interfacial interactions are affected by several competitive interfacial processes. By decreasing the ionic strength of the brine, the solubility of naphthenic acids in the aqueous solution increases, and hence,the conductivity and the pH of the aqueous phase decrease. To verify this important finding, UV-Vis spectroscopy and 'H NMR analysis were also performed on aged brine samples. Notably, there is an ionic strength of brine in which the lowest IFT is observed, while the other physical properties are remained relatively unchanged.

Regularities in the E. coli promoters composition in connection with the DNA strands interaction and promoter activity

The energy of interaction between DNA strands in promoters is of great functional importance. Visualization of the energy of DNA strands distribution in promoter sequences was achieved. The separation of promoters in groups by their energetic properties enables evaluation of the dependence of promoter strength on the energetic properties. The analysis of groups (clusters) of promoters distributed by the energy of DNA strands interaction in ?55, ?35, ?10 and +6 sequences indicates their connection with the transcriptional activity.

Tuning interaction strength between CeO_(2) and iridium to promote CO oxidation over Ir/TiO_(2)

The interaction between support and noble metal plays a crucial role in heterogeneous catalysis design.However,how to tune metal support interactions to optimize the activity still needs further exploration.CeO_(2) was introduced to promote CO oxidation ove r Ir/TiO_(2) by adjusting the interaction strength between iridium(Ir)and CeO_(2).The strong interaction between Ir and CeO_(2) blocks CO adsorption and causes low CO oxidation activity.However,introducing CeO_(2) on Ir/TiO_(2) produces localized interaction between Ir and CeO_(2),which can tune the surface electronic state of Ir,so a"volcano curve"relationship between CO oxidation activity and electronic state is built.Limited amount of CeO_(2) on Ir/TiO_(2)(Ir/Ce_(0.2)Ti)leads to CO complete oxidization at 22℃,and a new pathway for CO oxidation was explored.The study demonstrates that the utilization of tuning interaction strength between active metal and support is a potential method to increase the catalytic activity.

Structural strength deterioration of coastal bridge piers considering non-uniform corrosion in marine environments

In the aggressive marine environment over a long-term service period,coastal bridges inevitably sustain corrosion-induced damage due to high sea salt and humidity.This paper investigates the strength reduction of coastal bridges,especially focusing on the effects of non-uniform corrosion along the height of bridge piers.First,the corrosion initiation time and the degradation of reinforcement and concrete are analyzed for bridge piers in marine environments.To investigate the various damage modes of the concrete cover,a discretization method with fiber cells is used for calculating time-dependent interaction diagrams of cross-sections of the bridge piers at the atmospheric zone and the splash and tidal zone under a combination of axial force and bending moment.Second,the shear strength of these aging structures is analyzed.Numerical simulation indicates that the strength of a concrete pier experiences dramatic reduction from corrosion initiation to the spalling of the concrete cover.Strength loss in the splash and tidal zone is more significant than in the atmospheric zone when structures’service time is assumed to be the same.

喷水推进器进水流道格栅流固耦合特性研究

为了研究格栅部件对喷水推进船舶效率的影响,本文拟采用流固耦合的数值计算方法系统地对格栅表面受力及其强度特性进行计算,结合有限元方法和流固耦合理论,以STARCCM+和ABAQUS软件为工具,根据目前已知的格栅剖面设计方法,对目前格栅的剖面形式进行改进,形成新型对称剖面形式的格栅。基于上述计算流体力学与流固耦合计算方法对其进行周围流场、结构静力强度、结构动力强度进行计算与分析。结果表明:对称形式的格栅剖面对于降低格栅的变形与应力水平有一定的帮助,采用新型对称形式的剖面结构使格栅总体变形模式发生了变化,但是最大变形位置与最大应力出现在格栅的位置未发生明显变化,新型对称剖面形式格栅具有比较好的静强度与动强度特性,各栅条均匀承受流体载荷。

复合磨损套管爆裂失效机理及剩余强度预测

超深井、水平井、大位移井等复杂油气井服役工况异常恶劣,套管复合磨损严重,将对井筒完整性构成巨大威胁,且磨损套管剩余强度难以精准预测。为此,基于塔里木盆地塔中北坡顺南区块501井套管磨损数据及P110管材应力—应变本构关系,建立了充分考虑钻杆本体和接头联合造成的磨损模式、夹角、磨损重叠深度及磨损深度的复合磨损套管有限元力学模型,并开展了多种复合磨损模式下套管弹塑性变形、屈服、裂纹萌生、扩展及爆裂行为模拟,得到了不同复合磨损套管应力分布、剩余抗内压屈服强度及爆裂强度。研究结果表明:(1)月牙夹角在0°~90°时,应力干涉削弱应力集中,月牙夹角在90°~180°时,应力干涉增强应力集中,这种交互作用机制导致磨损套管剩余强度随着月牙夹角增加而先增加后降低;(2)裂纹萌生并起始于等效应力最大的位置即磨损月牙中心,并垂直于最大环向应力沿径向从套管内壁向外壁扩展,且裂纹一旦萌生,裂纹将迅速扩展并发生爆裂失效;(3)灰色关联度分析确定了复合磨损套管剩余强度对磨损深度、月牙夹角、复合磨损形式、月牙重叠深度的敏感性,分析结果表明磨损深度是决定套管剩余强度的主控因素。结论认为,该认识为套管强度设计与优化提供了技术参考,并对准确预测复合磨损套管剩余强度和确保井筒安全及完整性具有重要意义。

基于响应面法的复合改良膨胀土无侧限抗压强度研究

为提高膨胀土的无侧限抗压强度,降低工程危害。在木质素改良膨胀土的研究基础上,通过单因素试验研究纤维长度、纤维掺量及木质素掺量对膨胀土抗压强度的影响规律,基于单因素试验结果,通过BBD (BOX-Behnken design)响应面设计法进行响应面试验,建立二次回归模型,研究了双因素交互作用对膨胀土无侧限抗压强度的影响。结果表明:单因素作用时,膨胀土无侧限抗压强度在各因素作用下均呈现先增大后减小的趋势;双因素交互作用时,木质素掺量和聚丙烯掺量二者交互作用显著性最好。由BBD响应面法得到的最优组合为:聚丙烯纤维长度为9 mm、纤维掺量为0.3%、木质素掺量为3%,该变量下平行试验组的平均抗压强度为552.48 kPa,相比于素膨胀的抗压强度提升了76.97%,可见此方案下对素膨胀土的无侧限抗压强度提升效果最好。研究成果为新乡地区弱膨胀土的改良提供了借鉴,为复合改良土的试验设计提供了新思路。

场景互动电子生物反馈训练在女性压力性尿失禁中的临床应用研究

目的探讨场景互动电子生物反馈训练在尿失禁治疗中的作用。方法选取2020年12月—2023年6月之间福建省龙岩市第二医院妇产科收治的患有尿失禁的女性患者120例为研究对象,随机分为2组,各60例。对照组按常规在静卧体位下分步完成电刺激、生物反馈训练;试验组在场景互动下同步进行电刺激、生物反馈和场景生物反馈联合治疗。对比2组患者的盆底肌肌力、子宫脱垂分度、压力性尿失禁、个人生活社会功能评定量表(personal and social performance scale,PSP)、负性情绪[视觉模拟评分法(visual analogue scale,VAS)、文字描述评价量表(verbal descriptors scale VDS)]评价。结果试验组患者的盆底肌肌力、子宫脱垂分度、压力性尿失禁等指标均优于对照组,差异有统计学意义(P<0.05)。PSP评分试验组高于对照组,而试验组VAS评分(32.02±3.26)分、VDS评分(32.23±3.08)分,均低于对照组的(43.23±2.63)分、(44.63±3.09)分,差异有统计学意义(P<0.05)。结论场景互动电子生物反馈训练能有效改善女性尿失禁症状,降低子宫脱垂分度,提高盆底肌肌力与生活社会功能水平,改善不良情绪。

Stability analysis of longwall top-coal caving face in extra-thick coal seams based on an innovative numerical hydraulic support model

The relationship between support and surrounding rock is of great significance to the control of surrounding rock in mining process.In view of the fact that most of the existing numerical simulation methods construct virtual elements and stress servo control to approximately replace the hydraulic support problem,this paper establishes a new numerical model of hydraulic support with the same working characteristics as the actual hydraulic support by integrating numerical simulation software Rhino,Griddle and FLAC3D,which can realize the simulation of different working conditions.Based on this model,the influence mechanism of the supporting strength of hydraulic support on surrounding rock stress regulation and coal stability in front of the top coal caving face in extra thick coal seam were researched.Firstly,under different support intensity,the abutment pressure of the bearing coal and the coal in front of it presents the “three-stage”evolution characteristics.The influence range of support intensity is 15%–30%.Secondly,1.5 MPa is the upper limit of impact that the support strength can have on the front coal failure area.Thirdly,within a displacement range of 2.76 m from the coal wall,a support strength of1.5 MPa provides optimal control of the horizontal displacement of the coal.

Analytical prediction for time-dependent interaction of a circular tunnel excavated in strain-softening rock mass

Viscoelastic plastic solutions for tunnel excavation in strain-softening rock mass and tunnel-rock interaction are proposed based on the Mohr-Coulomb and the Generalized Zhang-Zhu(GZZ)strength criterion considering stress path.The solutions are verified by numerical simulations,results show that the theoretical solutions are close to the simulated data.The evolutions of rock stresses,strains,displacements and support pressure were investigated and the influences of residual strength parameter,support stiffness,support timing,initial support pressure and viscosity coefficient on the rock deformation and the support pressure are discussed by proposed solution.It is found that strain-softening results in large deformation and high support pressure,with stiffer support and a larger viscosity coefficient contributing to even greater support pressure.Ductile support is recommended at the first stage to release the energy and reduce the support pressure by allowing a relatively large deformation.The support pressure,especially the additional support pressure at the second stage will be much smaller if a higher initial support pressure is applied at the first stage.This can not only control the displacement rate of surrounding rock and improve the tunnel stability at the first stage by exerting sufficient support pressure immediately after tunnel excavation,but also greatly reduce the pressure acted on permanent support and improve the structure stability at the second stage.Therefore,to avoid the instability of support structure,ductile support,which could not only deform continuously but also provide sufficient high support pressure,is recommended at the first stage.

台风风速下风力机风轮流固耦合动力响应特性研究

将改进的流固耦合方法用于不同风速下风力机的载荷和响应特性研究,其准确性得到NREL数据和风力机叶片模态振动实验的验证。与传统的流固耦合方法相比,该方法减少了动网格使用数量、避免负体积网格,提高了计算稳定性,将计算时间缩短约50%。仿真结果表明,将风速由25 m/s提升至35 m/s,叶片的推力和扭矩载荷的波动振幅分别增加了6.8倍和9.8倍。同时,在叶片吸力面发现存在结构屈曲,这与台风现场叶片断裂位置接近,可能是风力机叶片结构在台风环境下的强度薄弱点,同时,在叶片吸力面发现存在结构屈曲,这与台风现场叶片断裂位置接近,是可能的风力机叶片结构在台风环境下的强度薄弱点。

基于等效电流源的级联混合直流馈入系统强度影响分析

级联型混合直流系统受端的模块化多电平换流器高压直流系统(modular multilevel converter high voltage direct current,MMC-HVDC)和电网换相换流器高压直流系统(line commutated converter high voltage direct current,LCC-HVDC)会因馈入点电气距离较近而存在强相互作用关系。为明确级联型混合直流馈入系统中MMC-HVDC对LCC-HVDC系统强度的影响,提出考虑幅值和相位的MMC等效电流源的简化等效方法,基于所提MMC等效原理将级联型混合直流馈入系统等效成单馈入LCC-HVDC系统,分析等效单馈入系统的参数计算方法,并提出等效单馈入短路比评估指标。最后通过该指标分析归纳了不同控制方式、不同电气距离下等效单馈入系统的系统强度变化情况,即为MMC-HVDC对LCC-HVDC系统强度的影响规律。机理分析和基于PSCDAD/EMTDC、MATLAB的仿真结果表明,所提等效方法具有有效性且所提指标能很好地反应MMC-HVDC对LCC-HVDC系统强度的影响。

浅层膨胀土及其纤维改良土的剪切强度特性

与膨胀土工程灾害密切相关的浅层膨胀土受到的围压通常较低,其力学特性有别于高围压下的情形.通过三轴剪切试验比较高、低围压下膨胀土的剪切行为及剪切强度的非线性特征,探讨聚丙烯纤维改良浅层膨胀土的剪切特性及加固机理.结果表明,浅层膨胀土剪切强度具有明显的非线性,可用幂函数表征.随着土体中水的质量分数增大和围压减小,膨胀土剪切强度非线性更加明显.采用高围压下的抗剪强度参数试验结果会导致浅层饱和膨胀土的黏聚力被高估225.7%、内摩擦角被低估42.5%.掺入纤维后膨胀土的剪切强度明显提高,提升幅度与土体中的三维纤维网状结构的形成度有关.增大纤维长度可以有效降低剪切强度衰减率,继而消弱膨胀土的应变软化效应;过长的纤维在膨胀土内容易弯曲和扭折,会导致纤维-膨胀土界面作用随着土体变形而逐渐劣化.

融合交互强度的优化社交推荐算法

针对现有社交化推荐算法忽视了评级数据与社交信息之间关联的探索,提出了一种融合交互强度的优化社交推荐算法。首先,利用社交信息和评级数据结合两种相似度丰富社交矩阵;接着,定义用户间交互强度代表用户间复杂关系;最后,利用交互强度与社交关系之间的关联以及用户潜在特征与用户群体参与特征的关联构建新的目标函数,学习用户和项目的潜在特征,实现个性化推荐。在三个真实数据集上进行实验,与基线模型相比,提出算法在推荐预测精度上有显著提升,且在对不同评级数量的用户进行潜在特征学习时,表现出良好的鲁棒性。综上,融合交互强度可以进一步提升社交化推荐算法性能,增强用户体验感。

Exploring the impact of weak measurements on exciton-exciton interactions

In our study of super quantum discord between two excitonic qubits inside a coupled semiconductor quantum dots system,our primary focus is to uncover the impact of weak measurement on its quantum characteristics.To achieve this,we analyze how varying the measurement strength x,affects this super quantum correlation in the presence of thermal effects.Additionally,we assess the effect of this variation on the system's evolution against its associated quantum parameters;external electric fields,exciton-exciton dipole interaction energy and F?rster interaction.Our findings indicate that adjusting x to smaller values effectively enhances the super quantum correlation,making weak measurements act as a catalyst.This adjustment ensures its robustness against thermal effects while preserving the non-classical attributes of the system.Furthermore,our study unveils that the effect of weak measurements on this latter surpasses the quantum effects associated with the system.Indeed,manipulating the parameter x allows the weak measurement to function as a versatile tool for modulating quantum characteristics and controlling exciton-exciton interactions within the coupled semiconductor quantum dots system.