The Effect of Mineral Composition and Quantity of Fines on the Atterberg Limits and Compaction Characteristics of Soils

Because of the various elements that come into play in natural soil formation, the impact of varied proportions of mineral composition and fines amount on Atterberg limits and compaction characteristics of soils is not well known. Three distinct soil samples were used in this investigation. The findings indicated the effect of varied mineral composition proportions and fines amount on the liquid limit, plastic limit, and plasticity index as assessed by the Casagrande test and hand-rolling method. The fluctuation of maximum dry density and optimal moisture content with these three soils has also been studied. Furthermore, correlations were established to indicate the compaction parameters and the amount of minerals and particles in the soil. The data show that the mineral content of the soil has a direct impact on the Atterberg limits and compaction characteristics. Soils containing larger percentages of expansive minerals, such as montmorillonite, have more flexibility and volume change capability. Mineral composition influences compaction parameters such as maximum dry density, ideal water content, axial strain, and axial stress. Soils with a larger proportion of fines, such as Soil 2 and Soil 3, have stronger flexibility and lower compaction qualities, with higher ideal water content and lower maximum dry density. Soil 1 has moderate flexibility and intermediate compaction qualities due to its low fines percentage. The effect of different mineral compositions and fines on the Atterberg limits and compaction characteristics of soils can be used to predict the behavior of compacted soils encountered in engineering practices, reducing the time and effort required to assess soil suitability for engineering use.

Soil Atterberg Limits and Consistency Indices as Influenced by Land Use and Slope Position in Western Iran

Atterberg limits and consistency indices are used for classifications of cohesive(fine-grained) soils in relation with compaction and tillage practices. They also provide information for interpreting several soil mechanical and physical properties such as shear strength, compressibility, shrinkage and swelling potentials. Although, several studies have been conducted regarding the land use effects on various soil mechanical properties, little is known about the effects of land use and slope positions on Atterberg limits and consistency indices. This study was conducted to investigate the effects of land use and slope position on selected soil physical and chemical properties, Atterberg limits and consistency indices in hilly region of western Iran. Three land uses including dryland farming, irrigated farming and pasture and four slope positions(i.e., shoulder, backslope, footslope, and toeslope) were used for soil samplings. One hundred eleven soil samples were collected from the surface soil(0-10 cm). Selected physical and chemical properties, liquid limit(LL), plastic limit(PL) and shrinkage limit(SL) were measured using the standard methods; and consistency indices including plastic index(PI), friability index(FI), shrinkage index(SI) and soil activity(A=PI/clay) were calculated. The results showed that irrigated farming significantly increased organic matter content(OM) and OM/clay ratio, and decreased bulk density(ρb) and relative bulk density(ρb-rel) as a result of higher biomass production and plant residues added to the soil compared to other land uses. Except for sand content, OM, ρb, cation exchange capacity(CEC) and calcium carbonate equivalent(CCE), slope position significantly affected soil physical and chemical properties. The highest values of silt, OM/clay and CEC/clay were found in the toeslope position, predominantly induced by soil redistribution within the landscape. The use of complexed(COC)- noncomplexed organic carbon(NCOC) concept indicated that majority of the studied soils were located below the saturation line and the OM in the soils was mainly in the COC form. The LL, PI, FI and A showed significant differences among the land uses; the highest values belonged to the irrigated farming due to high biomass production and plant residues returned to the soils. Furthermore, slope position significantly affected the Atterberg limits and consistency indices except for SL. The highest values of LL, PI, SI and A were observed in the toeslope position probably because of higher OM and CEC/clay due to greater amount of expandable phyllosilicate clays. Overall, soils on the toeslope under irrigated farming with high LL and SI and low values of FI need careful tillage management to avoid soil compaction.

Existence of Two Limit Cycles in Zeeman’s Class 30 for 3D Lotka-Volterra Competitive System

Gyllenberg and Yan(Discrete Contin Dyn Syst Ser B 11(2):347–352,2009)presented a system in Zeeman’s class 30 of 3-dimensional Lotka-Volterra(3D LV)competitive systems to admit at least two limit cycles,one of which is generated by the Hopf bifurcation and the other is obtained by the Poincaré-Bendixson theorem.Yu et al.(J Math Anal Appl 436:521–555,2016,Sect.3.4)recalculated the first Liapunov coefficient of Gyllenberg and Yan’s system to be positive,rather than negative as in Gyllenberg and Yan(2009),and pointed out that the Poincaré-Bendixson theorem is not applicable for that system.Jiang et al.(J Differ Equ 284:183–218,2021,p.213)proposed an open question:“whether Zeeman’s class 30 can be rigorously proved to admit at least two limit cycles by the Hopf theorem and the Poincaré-Bendixson theorem?”This paper provides four systems in Zeeman’s class 30 to admit at least two limit cycles by the Hopf theorem and the Poincaré-Bendixson theorem and gives an answer to the above question.

A Bayesian multi-model inference methodology for imprecise momentindependent global sensitivity analysis of rock structures

Traditional global sensitivity analysis(GSA)neglects the epistemic uncertainties associated with the probabilistic characteristics(i.e.type of distribution type and its parameters)of input rock properties emanating due to the small size of datasets while mapping the relative importance of properties to the model response.This paper proposes an augmented Bayesian multi-model inference(BMMI)coupled with GSA methodology(BMMI-GSA)to address this issue by estimating the imprecision in the momentindependent sensitivity indices of rock structures arising from the small size of input data.The methodology employs BMMI to quantify the epistemic uncertainties associated with model type and parameters of input properties.The estimated uncertainties are propagated in estimating imprecision in moment-independent Borgonovo’s indices by employing a reweighting approach on candidate probabilistic models.The proposed methodology is showcased for a rock slope prone to stress-controlled failure in the Himalayan region of India.The proposed methodology was superior to the conventional GSA(neglects all epistemic uncertainties)and Bayesian coupled GSA(B-GSA)(neglects model uncertainty)due to its capability to incorporate the uncertainties in both model type and parameters of properties.Imprecise Borgonovo’s indices estimated via proposed methodology provide the confidence intervals of the sensitivity indices instead of their fixed-point estimates,which makes the user more informed in the data collection efforts.Analyses performed with the varying sample sizes suggested that the uncertainties in sensitivity indices reduce significantly with the increasing sample sizes.The accurate importance ranking of properties was only possible via samples of large sizes.Further,the impact of the prior knowledge in terms of prior ranges and distributions was significant;hence,any related assumption should be made carefully.

THE APPLICATION OF WEINSTEIN-CHIEN′S METHOD——THE UPPER AND LOWER LIMITS OF FUNDAMENTAL FREQUENCY OF RECTANGULAR PLATES WITH EDGES ARE THE MIXTURE OF SIMPLY SUPPORTED PORTIONS AND CLAMPED PORTIONS

In this paper, the method of relaxed boundary conditions is applied to rectangular plates with edges which are a sort of the mixture of simply supported portions and clamped portions, so that the lower limit of fundamental frequency of such plates is evaluated. A kind of polynomial satisfying the displacement boundary conditions is designed, os that it is enabled to evaluate the upper limit of fundamental frequency by Ritz' method. The practical calculation examples solved by these methods have given satisfactory results. At the end of this paper, it is pointed out that the socalled exact solution of such plates usually evaluated by the force superposition method is essentially a kind of lower limit of solution, if the truncated error of series which occurs in actual calculation is considered.

饱和器后煤气中H_(2)S含量升高的原因及解决措施

分析了焦炉煤气中H_(2)S含量在脱硫工段达标,但在饱和器及终冷塔后再次升高的原因以及采取的措施。将一种新型高效除尘捕雾装置成功运用到脱硫工序,不仅使煤气中H2S含量稳定达标,对硫铵工序长期连续稳定运行也具有至关重要的作用。

生石灰-石粉-WSS固化剂在钻渣废弃土筑路再生中的应用

围绕钻渣废弃土含水率高、塑性指数大、施工性能差3个问题,设计了生石灰+石灰岩石粉的预处理方案,通过一系列室内试验,从脱水效率、界限含水率变化幅度、预处理后土颗粒形态和破碎难易度4个方面选择出最优配合比。之后使用矿渣-纳米复合土壤固化剂(WSS)对预处理土进行固化,以无侧限抗压强度(q_(u))、水稳定性(γ_(w))、加州承载比(CBR)和抗压回弹模量(E_(c))为指标评价固化效果,同时对预处理的辅助固化作用进行分析。除此之外,本试验还探究了最大粒径等级(D_(max))对固化土强度、破碎形态和水稳系数的影响。结果表明:本预处理方法能有效降低废弃土含水率并提高脱水速率,显著改善土体的界限含水率与颗粒形态,增进与粉末状固化剂的拌和效果。钻渣废弃土经“3%生石灰+3%石灰岩石粉+3%WSS”处理后,28 d龄期无侧限抗压强度(q_(u))为2.13 MPa,高于传统水泥固化方案和不进行预处理的固化方案。经分析得出,预处理剂可以絮凝-硬化黏土颗粒并疏松土体结构,还可以让土体呈碱性以增强WSS与水泥的固化效果。此外,试验证明了随着Dmax的减小,生石灰-石灰岩石粉-WSS固化土的强度和水稳定性逐步提高,破坏形式从脆性剪切破坏转变为塑性压缩破坏。

LIMITING EXPRESSION FOR GENERALIZED INVERSE A_(T,S)^(2) AND ITS CORRESPONDING PROJECTORS

This paper presents the limiting expression for the gen calized inverse A T.S(2) and itscorresgonding projectors Since comonon imnortors inverses,such as and AT.S(2) etc are all generalized in e e AT.S(2) In fact,we give a unified limiting formula of computine such imporiant generalined inverses and its corresponding proiectors,Based on this we estalish and imbedling method fire compoting the generalized in verse AT.S(2) The results extend earlier work by various authors.

Likely Limit Sets of a Class of p-order Feigenbaum's Maps

A continuous map from a closed interval into itself is called a p-order Feigenbaum＇s map if it is a solution of the Feigenbaum＇s equation fP（λx）=λf（x）. In this paper, we estimate Hausdorff dimensions of likely limit sets of some p-order Feigenbaum＇s maps. As an application, it is proved that for any 0 〈 t 〈 1, there always exists a p-order Feigenbaum＇s map which has a likely limit set with Hausdorff dimension t. This generalizes some known results in the special case of p =2.

Initial Rifting Age of the Nearly N–S Rifts in Southern Tibetan Plateau:New Evidence from the Age limit of the Early Sediments

Objective The nearly parallel N-S-trending rifts in southern Tibet represent the E-W extension of the Tibet Plateau. Most data which constrained the age of the extensional deformation come from isotopic dating of the dikes probably related to the activity of the nearly N-S faulting and micas from hydrothermal activity and the low- temperature thermochronology of plateau uplift. Previous research shows that there are at least three different ideas about the age of the rifts： （1） older than 16-12 Ma, （2） 14- 10 Ma, and （3） 8-4 Ma （Fig. la）. For the old sedimentary strata represented the beginning of the rifting, the dating of the sediments helps to better define the initial rifting age.

低变质煤H_(2)S异常和超限形成机理研究

为了研究彬长矿区雅店煤矿的H_(2)S异常和超限的形成机理,通过对矿井主采4号煤层地温条件、不饱和烃、硫酸盐分布、地下水pH值、硫酸盐还原菌(SRB)生存条件及采矿扰动等分析,认为研究区具有20~40℃适宜的地温条件和pH值为7.70~7.78的洛河组弱碱性水良好条件,为硫酸盐还原菌(SRB)苏醒和繁殖提供了生存条件,在硫酸盐还原菌(SRB)的还原作用下,使得煤层中的硫酸盐矿物被还原成为H_(2)S代谢排出(生),进入煤层孔裂隙等储存空间(储),受煤系地层顶底良好的封存作用使得H_(2)S得以保存,受采矿活动的影响,H_(2)S沿裂隙和地下涌水逸散至巷道回风流中(运—逸),造成H_(2)S局部异常和超限,构成了“生—储—保—运(移)—逸”H_(2)S形成机理和条件。

KELEA (Kinetic Energy Limiting Electrostatic Attraction) Offers an Alternative Explanation to Existing Concepts Regarding Wave-Particle Duality, Cold Fusion and Superconductivity

Existing explanations for several major phenomena in physics may need to be reconsidered in light of the description of a natural force termed KELEA (kinetic energy limiting electrostatic attraction). Three examples are selected for discussion in this paper: i) The proposed wave-particle duality of electrons;ii) cold fusion;and iii) superconductivity. The current interpretations of these enigmatic concepts are incomplete and not fully validated by scientific methods. The observations underlying these processes are seemingly consistent with KELEA acting as a repelling force between opposite electrical charges. Relatively simple experiments can be designed to either confirm or exclude KELEA in these and in various other currently perplexing physical phenomena.

Existence of a Limit Cycle in an Intraguild Food Web Model with Holling Type II and Logistic Growth for the Common Prey

In this paper, we prove the existence of a limit cycle for a given system of differential equations corresponding to an asymmetrical intraguild food web model with functional responses Holling type II for the middle and top predators and logistic grow for the (common) prey. The existence of such limit cycle is guaranteed, via the first Lyapunov coefficient and the Andronov-Hopf bifurcation theorem, under certain conditions for the parameters involved in the system.

Development of a Notion of Limit as Proximity From Discourse Analysis in Secondary-School Function Classes

Mathematical teaching and learning of an introductory calculus conception of limit in secondary school before students learn the formal definition of limit in higher education are discussed.In this study,applications of the theory of instruction based on“Formalizing Introductory Notions(FIN)”(Nagle,2013),in which a theory incorporating new pedagogical approaches was introduced to describe static notions of limit,without ignoring dynamic notions of limit,are presented to help foster an informal limit conception better aligned with the formal definition.A qualitative discourse analysis based on students’utterances,including students’drawing pictures on graphs,was done.In the results of the investigation,it was found that the students’utterances drawings on a graph of the secants(segments)used static notions of limit supported by dynamic notions of limit according to the operating activities.There were learning activities in which students developed a notion of limit as the proximity of the predicted tangent line of a function.Consequently,students’discussions changed focus to the validation of limit candidates with static notions of limit.To overcome the contradiction of their explanations of the operating activities with dynamic notions of limit,the students changed to an explanation with static notions of limit.In light of the findings,this study suggests adapting the pedagogical approach used by the Nagle(2013).

S波段YIG调谐限幅滤波器设计

依据YIG调谐限幅滤波器的工作原理,设计了一款S波段限幅滤波器。对滤波器进行了连续波限幅特性和抗烧毁功率测试,在S波段下,滤波器的限幅电平大于5 dBm,常温下最大为8 dBm;连续波输入情况下,滤波器的限幅输出功率小于10 dBm,为6.5 dBm;滤波器的抗烧毁功率大于50 W连续波,当脉冲输入峰值功率从2 W到200 W范围内变化时,滤波器的输出脉冲峰值功率被限制在18.5 dBm内,起到了很好的限幅滤波作用。试验证明设计的S波段YIG限幅滤波器不仅宽频段可调,具有良好的滤波特性,对高功率输入信号限幅输出,用于接收系统前端可有效保护后续电路的安全。

KINGWAY'S DREAM AND GLORY--Interviewing Shenzhen Brewery Company Limited's Manager General, Yuan Youjian and his colleagues

Why could Kingway, brand of Shenzhen Brewery CompanyLimited (SBC). in so short time realize its dream and acquire glories? What is its secret in success? What do itsdecision-makers look like? With all these questions, reporter interviewed mangaer general Yuan Youjian.

Third-Order Corrections and Mass-Shedding Limit of Rotating Neutron Stars Computed By a Complex-Plane Strategy

We implement the so-called “complex-plane strategy” for computing general-relativistic polytropic models of uniformly rotating neutron stars. This method manages the problem by performing all numerical integrations, required within the framework of Hartle’s perturbation method, in the complex plane. We give emphasis on computing corrections up to third order in the angular velocity, and the mass-shedding limit. We also compute the angular momentum, moment of inertia, rotational kinetic energy, and gravitational potential energy of the models considered.

钢悬链线立管S形铺设极限水深

针对南海某气田铺管船正常铺设钢悬链线立管(Steel Catenary Riser,SCR)的作业,基于OrcaFlex数值模拟对立管进行总体动态分析,确定立管可安全作业的阈值环境条件。研究波浪方向、海流速度、立管外径、壁厚等对立管正常铺设作业窗口的影响,进一步分析不同外径、壁厚立管在不同水深下的适用性,确定立管极限安装水深。研究表明,立管作业窗口对浪向较敏感,在随浪条件下进行铺管作业更安全。随着立管外径、壁厚、表面流速增大,波高-周期作业窗口减小,极限铺设水深减小。

The geomechanical properties of soils treated with nanosilica particles

This study examines the effect of nanosilica(NS)additive to improve the mechanical properties of clay,clayey sand,and sand.The engineering properties of the soils were investigated through Atterberg limits,compaction,unconfined compression,ultrasonic pulse velocity(UPV),freeze-thaw,and direct shear tests.The NS content varied from 0%to 0.7%and cement content was 5%and 10%by the dry weight of the soil.The curing period varied from 7 d to 150 d.The consistency,compaction,and strength properties of the soils were affected by the presence of NS and cement.The optimum NS contents in clay specimens with 5%and 10%cement were 0.5%and 0.7%,respectively.It was 0.7%in sand specimens with both cement ratios,as well as 0.3%and 0.7%in clayey sand specimens with 5%and 10%cement,respectively.In terms of freeze-thaw resistance,clayey sand specimens containing 0.5%NS and 10%cement had the minimum strength loss.Exponential relationships existed between the ultrasonic pulse velocity(UPV)and the unconfined compressive strength(UCS)of soil specimens having the same curing period.The shear strength parameters of the soils also improved with the addition of NS.Scanning electron microscope(SEM)images demonstrated that cement and NS contributed to the improvement of the soils by producing a denser and more uniform structure.It was concluded that the minor addition of NS could potentially improve the geomechanical properties of the soils.

The Sky’s the Limit

MARCH in Malawi was a significant time for women, In a month that traditionally celebrates the International Women＇s Day （IWD）, glass ceilings were being shattered. Malawi Airlines made history with an all-female operated and supported flight. The company celebrated IWD in style and boldness as an all-women crew took to the skies in a Bombardier Q400 flown from Blantyre in Mafawi to Dar es Salaam in Tanzania, with a stopover at Kamuzu International Airport （KIA） in Malawi.