Saturated Element Research Articles

Hydro-mechanical model for small-strain stiffness of unsaturated soil

This study aims to investigate a novel method for predicting the small-strain stiffness of unsaturated soil. A hydro-mechanical model is proposed to estimate the small-strain stiffness of unsaturated soil with various matric suction and stress states. A series of saturated and unsaturated bender element tests are conducted, and the test results indicate that the small-strain stiffnesses of saturated and unsaturated soil have similar changing trends with the variation of the stress state. The small-strain stiffness of unsaturated soil is calculated by the proposed model based on the test results of saturated soil. The model has two parameters that have a physical meaning and can be measured by tests. Thus, combined with the mature prediction model and measurement method of saturated soil and the proposed hydro-mechanical model, the complex unsaturated bender element tests are unnecessary. The proposed model is anticipated to be of practical value for solving engineering problems during the determination of small-strain parameters in the design of pits and foundations.

A comparison of two numerical models for modeling a twin tunnel in a saturated half-space

In this work an analytical as well as a numerical model are established for computing vibrations induced by a twin tunnel buried in a saturated poroelastic half-space. In the analytical solution the mechanical response for the half-space ground is expressed as a superposition of planar waves from the ground surface and cylindrical waves from two tunnel-soil interfaces. While in the numerical solution, three-dimensional saturated poroelastic finite element and multi-transmitting formula are formulated. The comparisons are made between the two methodologies, and the advantages and disadvantages of the two models are highlighted. Using the analytical one, the influence of the fluid in the soils, the reflection effect of the ground surface and the existence of a neighboring tunnel with or without a source on the mechanical response is investigated. By using the three-dimensional numerical model, the influence of various irregular tunnels on the surface vibration is investigated. The results suggest that: for the displacement and pore pressure response, the difference between one source tunnel and twin source tunnel can be up to 20 dB; the rectangular tunnels lead to the largest response followed by horseshoes and circular ones.

Numerical investigations on influences of tunnel differential settlement on saturated poroelastic ground vibrations and lining forces induced by metro train

The influences of the tunnel settlement on vibrations of the saturated poroelastic ground and on the additional forces of the tunnel lining are investigated numerically in this paper. A three-dimensional finite element model incorporating the metro train, the tunnel lining and the saturated ground has been established. The ground settlement is introduced into the computational model by a specifically developed vehicle-rail interaction (VRI) element, through which the metro train can be dynamically coupled to the track. The ground is considered as a saturated poroelastic medium that is discretized by a self-developed saturated-soil element based on Biot's theory. Moreover, at truncation boundaries of the ground model, an absorbing boundary condition termed multi-transmitting formula (MTF) that is specially developed for the saturated soil element is applied to meet the far-filed radiation condition. With the inputs of ground settlement data from in-situ measurement, amplifications in the ground vibration and the lining forces have been quantitatively determined by comparing to the settlement-free case. It is found that the ground vibrational velocity and acceleration can reach 40–60 times the responses when there is no differential settlement of the tunnel; the dynamic internal forces including the axial force, the shear force and the bending moment of the tunnel lining can be 7–20 times higher than their static counterparts. • The ground vibrational velocity and acceleration can be as high as 40–60 times the responses when there is no differential settlement of the tunnel. • The differential settlement of the tunnel has negligible influence on the vibration amplification zone at the ground surface. • The differential settlement of the tunnel not only induce static internal forces to the lining structure, but also prompt the wheel/rail interaction and considerably amplify the dynamic internal forces of the lining.

A user-defined element for dynamic analysis of saturated porous media in ABAQUS

Abstract General finite element software has unique advantages in solving complicated engineering problems, which has been widely applied in the dynamic analysis of single-phase media. However, the commonly used software does not provide a saturated porous two-phase element that can be adopted for dynamic analysis. In this paper, a user-defined element for dynamic analysis of saturated porous media is developed in the general finite element software ABAQUS. The user-defined element takes the displacements of solid skeleton and pore fluid as the basic unknown-variables, and adopts the implicit time integration scheme. By combining it with the equivalent linear method, the nonlinear dynamic analysis of saturated soil can also be realized. The correctness of the user-defined element is verified by solving four numerical examples.

Contribution of wetted clothing to body energy exchange and heat stress

Quantifying the impact of clothing thermal and evaporation resistance is essential to providing representative boundary conditions for physiological modeling. In many models, sweat is assumed to drip off the skin surface to the environment and is not captured in clothing. In high metabolic rate and high temperature and humidity conditions the sweat produced by the body has the potential to saturate semipermeable clothing ensembles, changing the assumptions of the model. Workers, athletes and soldiers commonly wear encapsulating versions of such clothing to protect against environmental hazards. A saturated clothing model is proposed based on the ASHRAE two-node model using a saturated spot element in parallel with the existing method to account for sweat absorbed in the clothing. The work uses fundamental heat and mass transfer principles, modifying the existing formula using clothing measurements and basic assumptions. The effectiveness of the model is demonstrated by comparing the predictions of the original and proposed models, to the results of 21 soldiers exercising. The soldiers wore combat pants and shirt, helmet, gloves, shoes, socks, and underwear, and walked in a thermal chamber for 2 h at 42.2 °C dry bulb temperature, 54.4 °C wet bulb temperature, 20% relative humidity, and airspeed of 2 m/s. Core temperature, seven skin temperatures, heart rate, and total sweat loss were measured. The original model provides an average core temperature difference compared with the human subject results of 1.31 °C (SD = 0.557 °C) while the modified model improves the final prediction of core temperature to within an average of 0.15 °C (SD = 0.383 °C). The new model shows an improvement in the prediction of human core temperature under the tested conditions where dripping sweat will saturate clothing. The format can be used in multi-segmented thermal models and can continue to be developed and improved as more information on wetted clothing properties become available.

Impacts of evaporation on subsurface flow and salt accumulation in a tidally influenced beach

AbstractWe coupled a mass‐transfer formulation of evaporation to the density‐dependent variably saturated finite element model MARUN to predict the salinity under realistic conditions in a beach in the Gulf of Mexico. The results showed that evaporation almost doubled the pore water salt concentration in the intertidal zone in comparison to the case with no evaporation. The results also showed that for the relatively wet atmospheric conditions, the maximum evaporation did not occur from the supratidal zone, rather from the intertidal zone, and it was due to the difference in moisture between pore water and atmosphere. The highest salinity occurred during the spring tide period, and extended into the neap tide period. When the atmospheric condition was assumed to be constant and conducive to large evaporation (high temperature and low air humidity), the maximum salinity region shifted to the supratidal zone and persisted there due to low mixing. The maximum salinity value in the intertidal zone for this case was not larger than that of the variable atmospheric condition case. However, the maximum was more landward than the (more realistic) variable atmospheric condition case, which suggests that accurate characterization of pore water salinity in tidally influenced beaches requires accurate knowledge of atmospheric conditions in addition to beach and hydraulic properties. The constant atmospheric condition simulations suggest that antecedent extreme conditions greatly affect the salinity in the supratidal zone but they are dampened in the intertidal zone.

Sub-micron mapping of GHz magnetic susceptibility using scanning transmission x-ray microscopy

We report submicron imaging (∼0.75 μm resolution) of complex magnetic susceptibility in a micron-size ferromagnetic heterostructure using time-resolved scanning transmission x-ray microscopy. The real and imaginary parts of the susceptibility are extracted from the phase and amplitude of the small-angle (<20°) rotational response of the local magnetization under microwave excitation. Frequency-dependent response patterns were observed in an incompletely saturated bilayer element. The technique is extensible to higher frequencies (to ∼10 GHz), better spatial resolution, and layer-specific measurement.

The Category of L-fuzzy Quantales

In this paper, the definition of the saturated element in quantale is given, Based on the coproduct of monoids, the concrete forms of the coproduct of unital quantales is obatined. Also, some properties of their are discussed. Key words: Quantale; Monoid; Saturated element; Coproduct; Category

Carbon Disulfide Assisted Polymerization of Benzene

The chemical transformation of benzene (C(6)H(6)) and carbon disulfide (CS(2)) binary solution under high pressure condition is investigated by means of Raman spectroscopy up to 6.8 GPa. On increasing the pressure, all the Raman bands of benzene decrease in intensity, whereas new broad bands start to be observed at 1520 and 1450 cm(-1), indicating that a highly cross-linked polymer is formed. The recovered sample is analyzed through Raman and FT-IR spectroscopy and is identified as a saturated hydrocarbon and element sulfur.

Influence of heterogeneity on unsaturated hydraulic properties: (1) local heterogeneity and scale effect

Spatial heterogeneity is ubiquitous in nature, which may significantly affect the soil hydraulic property curves. The models of a closed-form functional relationship of soil hydraulic property curves (e.g. VG model or exponential model) are valid at point or local scale based on a point-scale hydrological process, but how do scale effects of heterogeneity have an influence on the parameters of these models when the models are used in a larger scale process? This paper uses a two-dimensional variably saturated flow and solute transport finite element model (VSAFT2) to simulate variations of pressure and moisture content in the soil flume under a constant head boundary condition. By changing different numerical simulation block sizes, a quantitative evaluation of parameter variations in the VG model, resulting from the scale effects, is presented. Results show that the parameters of soil hydraulic properties are independent of scale in homogeneous media. Parameters of α and n in homogeneous media, which are estimated by using the unsaturated hydraulic conductivity curve (UHC) or the soil water retention curve (WRC), are identical. Variations of local heterogeneities strongly affect the soil hydraulic properties, and the scale affects the results of the parameter estimations when numerical experiments are conducted. Furthermore, the discrepancy of each curve becomes considerable when moisture content becomes closer to a dry situation. Parameters estimated by UHC are totally different from the ones estimated by WRC. Copyright © 2012 John Wiley & Sons, Ltd.

Influence of heterogeneity on unsaturated hydraulic properties (2) - percentage and shape of heterogeneity

In subsurface porous media, the soil water retention curve (WRC) and unsaturated hydraulic conductivity curve (UHC) are two important soil hydraulic property curves. Spatial heterogeneity is ubiquitous in nature, which may significantly affect soil hydraulic property curves. The main theme of this paper is to investigate how spatial heterogeneities, including their arrangements and amounts in soil flumes, affect soil hydraulic property curves. This paper uses a two-dimensional variably saturated flow and solute transport finite element model to simulate variations of pressure and moisture content in soil flumes under a constant head boundary condition. To investigate the behavior of soil hydraulic property curves owing to variations of heterogeneities and their arrangements as well, cases with different proportions of heterogeneities are carried out. A quantitative evaluation of parameter variations in the van Genuchten model (VG model) resulting from heterogeneity is presented. Results show that the soil hydraulic properties are strongly affected by variations of heterogeneities and their arrangements. If the pressure head remains at a specific value, the soil moisture increases when heterogeneities increase in the soil flumes. On the other hand, the unsaturated hydraulic conductivity decreases when heterogeneities increase in the soil flumes under a constant pressure head. Moreover, results reveal that parameters estimated from both WRC and UHC also are affected by shapes of heterogeneity; this indicates that the parameters obtained from the WRC are not suitable for predicting the UHC of different shapes in heterogeneous media. Copyright © 2011 John Wiley & Sons, Ltd.

The Coproduct of Unital Quantales

In this paper, the definition of the saturated element in quantale is given, Based on the coproduct of monoids, the concrete forms of the coproduct of unital quantales is obatined. Also, some properties of their are discussed. KeyWords: Quantale; Monoid; Saturated element; Coproduct; Category

Fitness-Associated Sexual Reproduction in a Filamentous Fungus

Sex is a long-standing evolutionary enigma. Although the majority of eukaryotes reproduce sexually at least sometimes [1-3], the evolution of sex from an asexual ancestor has been difficult to explain because it requires sexually reproducing lineages to overcome the manifold costs of sex, including the destruction of favorable gene combinations created by selection [4, 5]. Conditions for the evolution of sex are much broader if individuals can reproduce either sexually or asexually (i.e., facultative sex) and allocate disproportionately more resources to sex when their fitness is low (fitness-associated-sex or FAS [6-10]). Although facultatively sexual organisms have been shown to engage in more sex when stressed [11], direct evidence for FAS is lacking. We provide evidence using 53 genotypes of the filamentous fungus Aspergillus nidulans in a reciprocal transplant experiment across three environments. Different genotypes achieved highest fitness in different environments and genotypes invested relatively more in sex in environments in which their fitness was lower, showing that allocation to sexual reproduction is a function of how well-adapted a genotype is to its environment. FAS in A. nidulans is unlikely to have evolved as a strategy to resist or avoid stress because asexual spores are more dispersive and equally resistant [12, 13].

Simulation of processes of formation of diffusion zone at limited solubility of saturated element in the alloy

A mathematical model and a software realization of the model of the process of diffusion saturation with elements in a system with limited solubility of the diffusing component are suggested. The adequacy of the mathematical model and its consistency with physical concepts of the mechanism of mass transfer of diffusing element under conditions of multiphase systems is shown.

Modified Pseudoinverse Redistribution Methodsfor Redundant Controls Allocation

Introduction I N recent years, control allocation problems have been intensively studied following the work of Durham.1−3 There are several solution methods: direct control allocation,1−3 daisy chaining,4 a linearprogramming (LP) method,5−6 a quadratic-programming (QP) method,7−11 and a pseudoinverse-redistribution (PIR) method.10−13 In this Note, a PIR method is discussed. A pseudoinverse has been used as a selector or a distributor.14 Shtessel et al. applied a pseudoinverse to the control allocation problem for a tailless aircraft.15 However, it is fixed, and it does not consider the control surfaces’ limits. Virnig and Bodden developed a PIR method for a short takeoff and vertical landing aircraft and then demonstrated the algorithm by means of a simulator.12 The PIR method repeats the process of calculating a pseudoinverse and a control vector by setting the saturated elements of a control vector to their limit values until a solution is obtained or there is no unsaturated element. Bordignon and Bessolo developed a modified method and applied it to the X-35 aircraft’s control allocation problem.16 Although the PIR method sets the saturated control elements to their limit values, the modified method selects only one saturated element and sets it to its limit value during the redistribution process. The purpose of this Note is to propose other modified methods and to compare them with the conventional PIR method and Bordignon and Bessolo’s method. A different selection of one saturated element results in a difference in performance. For this purpose, two different selections are proposed. The performance metrics of concern are the calculation times, the percentage of times that a method converges to an optimal solution, and the characteristics of the errors between the optimal solutions and the redistributed solutions. Numerical examples are presented for comparisons.

Definition and application of topological index based on bond connectivity

Bond connectivity topological index Si based on chemical bonds was defined by using a matrix method. And Si is formed by atomic parameters such as the number of valence electrons, the number of the highest main quantum of atoms and the bonding electrons and bond parameters such as the length of bonds, the electronegativity difference of bonding atoms. The molecular bond connectivity topological index S is composed of Si. The thermodynamic properties of saturated hydrocarbons, unsaturated hydrocarbons, oxygen organic, methane halide and transitional element compounds and the molecular bond connectivity topological index S have an optimal correlative relationship.

Novel self-synchronization scheme for high-speed packet TDM networks

We demonstrate a novel self-synchronization scheme for high-speed packet time-division-multiplexed (TDM) networks using a fast saturated, but slowly recovered gain (or loss) combined with intensity discrimination. The marker pulse used in this self-synchronization scheme is the same as other pulses in the packets. In particular, we use a semiconductor optical amplifier (SOA) as the fast saturated but slowly-recovered gain element, and an unbalanced nonlinear optical loop mirror or a dispersion-shifted fiber/optical filter combination as an intensity discriminator. The contrast ratio of the first pulse to the remaining pulses of a 100 Gb/s packet, "10111000" is >3 dB at the output of the SOA and >20 dB at the outputs of both intensity discriminators.

A unique high Mn/Fe microgabbro in the Parnallee (LL3) ordinary chondrite: nebular mixture or planetary differentiate from a previously unrecognized planetary body?

The study of planetary materials in chondritic meteorites constrains the compositional diversity of materials in different nebular environments and provides information on the degree of differentiation of early planetary bodies. We studied a unique microgabbro fragment from the Parnallee (LL3) unequilibrated ordinary chondrite. The fragment, which was originally identified by its ophitic to sub-ophitic texture, exhibits features characteristic of lunar and terrestrial tholeiitic basalts—extreme compositional zoning in clinopyroxene (Wo 10En 65Fs 25 to Wo 15En 2Fs 83), a multiply saturated major element composition similar to mid-ocean ridge basalt with 3.1 wt% Na 2O and 0.15 wt% K 2O, and uniformly enriched rare earth elements (c.10 × C1). A high bulkMnO/FeO ratio (0.064) distinguishes the microgabbro from other basaltic rocks and suggests the precursor material formed or reached equilibrium in a reducing environment. However, the absence of Fe metal and the extreme enrichment of FeO (up to 40 wt%), in late crystallizing pyroxferroite, requires the last crystallization event to have occurred in a relatively oxidizing environment. We suggest the microgabbro formed by partial melting in a planetary body after removal of metallic Fe. Examination of possible planetary source materials, such as alkali-rich eucritic material, a volatile-depleted C1 carbonaceous chondrite or H-group chondrite, shows that multiple-stage fractionation is required to produce a melt with theFeO/MgO ratio of the microgabbro from these materials. The increasing number of planetary igneous fragments observed in unequilibrated ordinary chondrites (UOC) suggests the picture of UOC as primitive assemblages of unprocessed material is overly simplistic.

Non-stationary jump phenomena of non-linear control systems by statistical linearization method†

The jump phenomena observed on the output signal of non-linear control systems subjected to non-stationary gaussian random inputs are presented. The analytical procedure is carried out by using the statistical linearization technique. As a numerical example, the mean squared values and the jump phenomena on tho responses of nonlinear control systems containing the saturated element with random disturbance like a sudden gust of wind or an earthquake are discussed.

Statistical Evaluation of Response of Non-Linear Servosystems to a Sinusoidal Signal and a Gaussian Disturbance

In this paper, a linearization approach for automatic control systems with a non-linear element of zero-memory characteristic under a sinusoidal input and a Gaussian disturbance is described. The response of the system to these inputs is too complicated to be analyzed precisely. However, if the equivalent gains of non-linear elements are evaluated for various values of parameters, the calculation of the response will readily be performed by means of graphical and numerical methods, and the effect of the non-linearities on the system performance will be found. As a typical example for the application of general description, the statistical evaluation of the error signal in a non-linear servosystem containing a saturated element with dead band under a sinusoidal input and a Gaussian disturbance is treated by a graphical method.