Saturated Materials Research Articles

Contact sorption: a method to reduce the moisture content of coal fines

ABSTRACTThis paper introduces contact sorption with ceramic sorbents as a method to reduce the moisture content of coal fines produced by coal processing plants. The proposed method was tested on laboratory scale where ceramic spheres with diameters of 3 mm and 5 mm were combined with wet coal fines of size fractions between 0.25 mm and 2 mm. The coal had an initial moisture content of 0.25 g(Water)/g(Coal and water), and was dewatered using contact sorption to an average moisture content of 0.13 g(Water)/g(Coal and water) after 2.5 minutes and 0.05 g(Water)/g(Coal and water) after 10 minutes, respectively. This paper focuses on identifying the solid phase conditions essential to improving the contact sorption drying technology, proving that contact between the coal and sorbent material is the main driving force behind this technology. Increasing the sorbent to coal mass ratio and using smaller sorbents with a larger surface area resulted in improved contact and consequently improved moisture mass transfer. The final coal moisture content that could be achieved was independent of coal particle size. Current studies show a reliance on thermal drying technologies to dry the saturated sorbent material, whereas this paper proves that drying with high airflow at low temperatures is sufficient to regenerate the sorbent material. The loaded sorbent material could easily be separated from the dried coal product by dry screening, and could be dried and regenerated afterwards in an air-blown packed bed within 10 minutes. The re-use of sorbent material showed no decrease in its dewatering efficiency, and it was shown to be possible to re-use the sorbents for a large number of cycles. Contact sorption can prove to be a cost-effective and efficient drying method to dewater coal fines in the industry.

Properties of Love Waves in Functional Graded Saturated Material.

In the present study, the propagation of Love waves is investigated in a layered structure with two different homogeneity saturated materials based on Biot’s theory. The upper layer is a transversely isotropic functional graded saturated layer, and the substrate is a saturated semi-space. The inhomogeneity of the functional graded layer is taken into account. Furthermore, the gradient coefficient is employed as the representation of the relation with the layer thickness and the material parameters, and the power series method is applied to solve the variable coefficients governing the equations. In this regard, the influence of the gradient coefficients of saturated material on the dispersion relations, and the attenuation of Love waves in this structure are explored, and the results of the present study can provide theoretical guidance for the non-destructive evaluation of functional graded saturated material.

Second law analysis for nonlinear convective flow of a reactive couple stress fluid through a vertical channel

The present article investigates the entropy generation rate in the nonlinear convective flow of a reactive couple stress liquid through a channel filled with saturated materials and subjected to convective cooling. Analytical solutions of the coupled nonlinear boundary-value problems arising from the mathematical formulation are obtained by using the Homotopy Analysis Method (HAM). The analytical solutions are further validated numerically with the fourth order Runge-Kutta (RK4) to establish the accuracy of the method. Velocity, temperature, entropy generation, and heat irreversibility ratio profiles are presented and discussed extensively. The result of the computation shows that entropy generation increases significantly with increasing buoyancy parameter.

The oscillating solitons for a coupled nonlinear system in nanoscale saturated ferromagnetic materials

Abstract A coupled nonlinear system is investigated, which describes the nonlinear short-wave propagation in nanoscale saturated ferromagnetic materials. A series of analytic solutions is constructed via Riccati equation mapping method. Furthermore, two types of novel periodically oscillating solitons are observed by choosing the arbitrary function in the soliton solution as trigonometric function and Jacobian elliptic function, respectively. The parameters can be used to control the compression, stretch, oscillating amplitude and frequency of the solitons.

Effect of inertia on double diffusive bidispersive convection

Convection thresholds in a saturated bidisperse porous material are calculated in the presence of a non-zero coefficient of inertia, the acceleration coefficient, for the fluid velocity in the macro pores. We concentrate on the case where the layer is heated from below and simultaneously salted from below. The effect of increasing the size of the acceleration coefficient is generally to increase the critical Rayleigh number above which convective motion commences, although the precise values depend on the interaction coefficient between the micro and macro pores, the porosities, and the Lewis number.

Presence of organohalide-respiring bacteria in and around a permeable reactive barrier at a trichloroethylene-contaminated Superfund site

Trichloroethylene (TCE) is one of the most common groundwater contaminants in the United States; however clean-up efforts are a challenge due to its physical and chemical properties. TCE and several of its degradation products were detected in the groundwater of the Beaver Dam Road Landfill site (Beltsville, MD) at concentrations above accepted maximum contaminant levels. A permeable reactive barrier (i.e., biowall) was installed to remediate the groundwater. Microbial infiltration and colonization of the biowall with native site bacteria was expected to occur. An array of molecular biological tools was applied to survey the microbial community for presence of organohalide-respiring microorganisms at the site. Microorganisms belonging to methanogens, acetogens, sulfate-reducing bacteria, and chlorinated aliphatic hydrocarbon-metabolizing bacteria were identified, thus making way for the application of the microbial populations in the biowall bioaugmentation efforts. In concomitant laboratory studies, molecular approaches were used to monitor continuously-fed column reactors containing saturated biowall material spiked with a commercially-available, Dehalococcoides-containing culture (SDC-9), with or without zero-valent iron (ZVI) shavings. The column without ZVI had the highest abundance of Dehalococcoides spp. (2.7 × 106 cells g−1 material, S.D. = 3.8 × 105 cells g−1 material), while the addition of ZVI did not affect the overall population. Although the addition of ZVI and biostimulation did change ratios of the Dehalococcoides strains, the results suggests that if ZVI would be applied as a biowall material amendment, biostimulation would not be required to maintain a Dehalococcoides population. These experimental results will be utilized in future remediation and/or biowall expansion plans to utilize the natural resources most effectively at the biowall site.

Femtosecond Tm–Ho co-doped fiber laser using a bulk-structured Bi2Se3 topological insulator**Project supported by the National Research Foundation of Korea (NRF) Grant Funded by the Korea Government (MSIT), Republic of Korea (Grant No. NRF-2018R1A2B6001641), Ministry of Science and ICT (MSIT) under the Information Technology Research Center (ITRC) Support Program (Grant No. IITP-2018-2015-0-00385), and supervised by the Institute for Information and Communications

We experimentally demonstrate a femtosecond mode-locked thulium–holmium (Tm–Ho) co-doped fiber laser incorporating a saturable absorber (SA) based on a bulk-structured bismuth selenide (Bi2Se3) topological insulator (TI). The SA was prepared by depositing a mechanically exfoliated Bi2Se3 TI layer onto a side-polished optical fiber platform. Unlike high-quality nano-structured Bi2Se3 TI-based SA, bulk-structured Bi2Se3 with non-negligible oxidation was used as a saturable absorption material for this experimental demonstration due to its easy fabrication process. The saturation power and modulation depth of the prepared SA were measured to be ∼28.6 W and ∼13.4%, respectively. By incorporating the prepared SA into a Tm–Ho co-doped fiber ring cavity, stable soliton pulses with a temporal width of ∼853 fs could be generated at 1912.12 nm. The 3-dB bandwidth of the mode-locked pulse was measured to be ∼4.87 nm. This experimental demonstration reaffirms that Bi2Se3 is a superb base material for mid-infrared passive mode-locking even under oxidation.

Nonlocal scale effect on Rayleigh wave propagation in porous fluid-saturated materials

In this paper, a Rayleigh wave model in fluid saturated porous materials based on a nonlocal Biot theory is proposed. The general characteristic equations expressed in terms of the Rayleigh wavenumbers are obtained. A specific fluid saturated porous material is used for numerical analysis. The present study shows that the nonlocal parameter does not have significant influence on the characteristics of Rayleigh waves within a low frequency range when comparing with the prediction of using the classical Biot theory. However, the influence of the nonlocal scale effect on the Rayleigh wave velocity and the displacement field becomes stronger as the response frequency increases. When the frequency exceeds a critical value, the Rayleigh wave velocity exhibits a negative dispersion. The displacement fields induced by the Rayleigh wave propagating in porous materials are also presented. An interesting phenomenon of the displacement fields is observed that the major axis of the displacement field ellipse will have a contra-rotation with respect to the vertical direction with increasing depth. This is different from the classical prediction in homogeneous materials. The presence of the nonlocal scale effect can also change the geometry property of displacement fields. In addition, the amplitude of the vertical displacement is attenuated along the depth, while the increment of the nonlocal parameters can strengthen the attenuation.

Antimonene: a long-term stable two-dimensional saturable absorption material under ambient conditions for the mid-infrared spectral region

We experimentally demonstrate a long-term stable two-dimensional saturable absorption material under ambient conditions—multi-layer antimonene feasible for the mid-infrared spectral region—for the first time to our knowledge. The multi-layer antimonene material prepared using a liquid-phase exfoliation method was coated on a quartz/CaF2 for characterizations and an Au mirror as a reflection-type saturable absorber (SA) device. It has a modulation depth of 10.5%, a saturation peak intensity of 0.26 GW/cm2, and a non-saturation loss of 19.1% measured at 2868.0 nm using the typical power-dependent method. By introducing the SA device into a linear-cavity Ho3+/Pr3+-codoped fluoride fiber laser at 2865.0 nm, stable Q-switched pulses were obtained. It generated a maximum output power of 112.3 mW and pulse energy of 0.72 μJ, while the shortest pulse duration and largest repetition rate were 1.74 μs and 156.2 kHz, respectively. The long-term stability of the SA device was also checked using the same laser setup within 28 days. The results indicate that multi-layer antimonene is a type of promising long-term stable SA material under ambient conditions that can be applied in the mid-infrared spectral region.

Geotechnical properties of compacted biosolids for monofill design, As-Samra, Jordan

This paper presents the results of a comprehensive geotechnical laboratory testing for the assessment and design of a proposed biosolid monofill facility at the As-Samra Waste Water Treatment Plant (WWTP) in Jordan. Previous landfill operations for biosolid materials typically involved co-disposal or lagooning of the dewatered biosolid slurry. However, it is proposed that the solar-dried As-Samra WWTP biosolid material will be placed in a new monofill facility at the site. This approach is suited to the As-Samra desert climate, since the material’s water content can be readily reduced to between 60 and 100% in evaporation lagoons. New insights were gained on the strength and compressibility of the non-inundated and saturated compacted biosolid materials, including their (a) very low normalised undrained strength ratio and effective angle of shearing resistance values for the saturated normally consolidated states of 0·14 and 15°, respectively; (b) very high strain rate dependency of strength; and (c) extremely low permeability coefficient values on the order of 10−12 m/s for compaction at approximately 100% water content. The paper concludes with recommendations on the appropriate water content range for compaction of the material in the proposed monofill and the selection of design strength values for geotechnical stability analysis.

A COMSOL-PHREEQC interface for modeling the multi-species transport of saturated cement-based materials

A COMSOL-PHREEQC interface based on MATLAB language is developed to simulate a multi-dimensional and multi-species ionic transport for cement-based materials. This interface couples the physical and chemical interactions between pore solution and cement hydrates (PHREEQC) into the Nernst-Planck equations (COMSOL) using a sequential non-iterative approach (SNIA). Based on the thermodynamic insight, the phase-equilibrium model and the surface complexation model are used to express the physical and chemical interactions. In addition, the influence of the variation of the porosity on the ionic transport is considered. Moreover, two reported experiments are taken as an example to illustrate the application of the interface and to verify its accuracy. The results indicate that the developed interface can accurately predict the transport of chloride in cement-based materials.

Experimental study on distributed optical fiber heated-based seepage behavior identification in hydraulic engineering

The theoretical analysis and physical experiment on seepage behavior identification with distributed optical fiber temperature sensor system (DTS) are implemented. The distributed optical fiber-based approaches monitoring the seepage velocity and phreatic line in embankment dam or dike engineering are proposed. Firstly, the physical heat transfer process between optical fiber and porous material is analyzed. The basic principle identifying seepage behavior according to optical fiber temperature is presented. Secondly, a DTS-based test platform identifying seepage behavior in embankment dam or dike engineering is developed. Thirdly, the heat transfer coefficient in heat transfer theory is adopted to describe the heat transfer between optical fiber and saturated porous material. The experimental analysis for the relationship between overall heat transfer coefficient (i.e., the ratio of heating power and temperature rise) and seepage velocity is implemented. The mathematical model representing above relationship is built and an empirical method is given to monitor the seepage velocity in hydraulic engineering. Fourthly, the effect of moisture content on optical fiber temperature rise is analyzed by the experiment. The optical fiber arrangement plan is designed to monitor the phreatic line in embankment dam or dike engineering, the method is proposed to determine the position of phreatic line.

Dilative behavior of kaolinite under drained creep condition

This paper studies the dilative behavior of clay during drained creep along triaxial tests under constant mean effective stress, where the volumetric strain is caused by the sole deviatoric stress variation. Tests were conducted on a saturated reconstituted clayey material by the use of a GDS stress path control apparatus. The development of the axial and volumetric strains was studied with respect to time, stress level (SL) and overconsolidation ratio (OCR). Analysis of the results ascertained that both dilatancy and contractancy phenomena could occur during creep. The magnitude of the dilatancy/contractancy during creep was guided by the test conditions (SL and OCR), which specifically governed the direction of the volumetric strain variations. The position of the stress level vis-a-vis the different volumetric domains defined by monotonic triaxial tests in the (p′–q) plane controls the evolution of the volumetric creep strain. The failure of an overconsolidated specimen could be observed for a stress level located under the maximum strength envelope, but above the critical state line in the p′–q plane, accompanied by a significant dilative behavior during creep.

The strength of ice-saturated extraterrestrial rock analogs

In situ resource utilization (ISRU) activities have been identified by the National Research Council as one of the most important scientific endeavors of the coming decade. The failure of the MUPUS-PEN experiment on Rosetta's Philae lander to penetrate the surface of comet 67P demands knowledge of the mechanical properties of extraterrestrial materials in such environments. To such an end we conducted laboratory strength measurements at cryogenic conditions of two terrestrial rocks, Bishop tuff and Indiana limestone as potential cometary and asteroid analogs, respectively. We measured failure strength of dried and fully saturated samples under constant displacement rate compressional loading at temperatures of 77 K–295 K and (for most) confining pressure of 5 MPa. The strength of saturated samples increased dramatically with decreasing temperature below the ice point: saturated limestone from 30 MPa at 295 K to >200 MPa at 150 K and below, and saturated tuff from 26 MPa at 240 K to 160 MPa at 150 K. Some ductility or distributed fracturing was evident in both saturated rock types above 150 K. The saturated tuff was stronger than pure ice at all conditions but its transition from brittle to ductile deformation with temperature closely paralleled that of ice. The results of this study will be useful to future sample retrieval missions or ISRU maneuvers. The fully saturated state of our samples and use of Bishop tuff as an unconsolidated cometary analog likely means our results are upper estimates for substrates we may encounter in our solar system. Pending corroboration and refinement of these preliminary measurements, the large increase in compressive strength we observed in the saturated materials at cryogenic temperatures suggests that future missions must prepare technology with the energetic and mechanical capability to penetrate very hard substrates.

Role of particle breakage in primary and secondary compression of wet and dry sand

The results of one-dimensional compression tests on dry and saturated crushable sand are analysed in order to identify the role of wetting and particle breakage on primary and secondary compression. Test results indicate that flooding dry samples at constant stress promotes particle breakage and triggers collapse from the characteristic compression curve of the dry material to the compression curve of the initially saturated material. The analysis shows that the link between the one-dimensional compressibility index and the amount of particle breakage does not depend on the stress level or the wetting condition. Furthermore, creep is promoted after flooding and the secondary consolidation index increases essentially up to the same value obtained in initially saturated samples. These findings suggest that the effect of flooding on both primary and secondary compression can be predicted only from dry and saturated tests.

A new approach for determination of gas breakthrough in saturated materials with low permeability

Gas breakthrough is one of the key characteristics for saturated geological materials with low permeability encountered in deep geological disposal of high-level radioactive waste, shale gas extraction and CO2 capture-geological storage, etc. Although gas breakthrough phenomenon is widely investigated in previous researches, the essential mechanisms are still not clearly explained. In the present work, a new approach for determination of gas breakthrough mechanism was proposed and a series of gas injection tests were conducted for verification. According to the theoretical analysis, the capillary effect, mechanical effect, as well as the interfacial leakage can induce gas breakthrough. The capillary breakthrough indicates the displacement of liquid phase driven by the capillary effect to form continuous flow pathway across the specimen. The mechanical breakthrough indicates the mechanically induced dilatancy of flow pathways followed by a significant decrease of the capillary flow resistance in the specimen. The interfacial breakthrough indicates the failure of the sealing capacity of the lateral boundary during the gas injection test. Based on the inherent characteristics, deformation properties of the specimen, as well as the boundary conditions, relationships between the capillary/mechanical/interfacial breakthrough pressure and the confining pressure were established, which can be used to determine the triggering mechanism of the gas breakthrough. Constant-volume and constant-isotropic stress gas injection tests were subsequently conducted for verification of the proposed approach. Results showed that the mechanical breakthrough is the most likely mechanism for the low permeability specimens tested in the present work.

Large-Scale Triaxial Experiments on the Creep Behavior of a Saturated Rockfill Material

AbstractLarge-scale triaxial compression and creep experiments were conducted with a saturated limestone rockfill material. The relationships between dilatancy ratio and stress ratio during loading...

Behaviour of saturated railway track foundation materials during undrained cyclic loading

This paper presents results of a series of hollow cylinder tests carried out to investigate the undrained behaviour of saturated railway track foundation materials during cyclic loading involving principal stress rotation. Four sand–clay mixes representative of real railway track foundation materials were investigated. It was found that moderate additions of clay (up to ∼14% by weight) increased the cyclic shear stress threshold at which significant excess pore pressures started to accumulate. After the cyclic shear stress threshold had been exceeded, the rate of pore pressure increase with the logarithm of axial strain was greatest for the material having a clay content of 11%. Excess pore pressure generation reduced with increasing intergranular and global void ratio, with the global void ratio being perhaps the more useful indicator because of the reduced amount of scatter and higher correlation of the idealized relationship.

Use of saturated green material in vaporic thermal atmosphere to absorb ions have negative impact

This design has been used to adsorb ions from industrial water of companies and factories. Our system has three integrated phases used to test efficiency of an unspecified number of residues of food as adsorbed materials. In this system, we adsorb copper and cobalt ions, these ions are available with high rates in Al Musayab thermal station, high concentration of these ions pose a threat to the health of the population. In general, the presence of these ions in the proportions set by the World Health Organization, namely, (1mg/L) are very useful for the com-pletion of the metabolic processes of the living cell, but a greater focus for this will lead to tremendous health risks. Testing processes a proved that there is an exact match between empirical and theoretical testes of (Freundlich and Langmuir) models. Through the mathematical analysis of the trial data under different thermal conditions, all testes proved that green algae powder is the best filtered material, because its high adsorption efficiency which equal to (77%) with Gips free energy equal to (-39 kJ/mol), followed by Pulp date powder has proven to be excellent efficiency (75%) with enthalpy equals to (-12 kJ/mol). In general, all food remnants have been selected to be test in our adsorp-tion system, this system has high capacity to adsorb various ionic roots of industrial water of Al-Musayab thermal station. All Adsorbents have thermal coefficient falls between one and zero (one<RL<0), this value represents the perfect choice of adsorption to be tested on this system. The total system cost is ($10000).

Q-switched all-fiber laser with short pulse duration based on tungsten diselenide

Fiber lasers are widely used in industrial processing, sensing, medical and communications applications due to their simple structure, good stability and low cost. With the rapid development of fiber lasers and the sustained improvement of industrial laser quality requirements, researchers in ultrafast optics focus on how to get laser pulses with high output power and narrow pulse duration. Q-switched technology is one of the most effective techniques to generate ultrashort pulses. In this paper, a tungsten diselenide saturable absorber with 16.82% modulation depth is prepared by chemical vapor deposition. Experimental results show that when the pump power changes from 115.7 mW to 630 mW, the all-fiber laser can achieve a stable Q-switched pulse output. The repetition rate of the output pulse varies from 80.32 kHz to 204.2 kHz, the pulse duration is 581 ns, the maximum output power is 17.1 mW and the maximum pulse energy is 83.7 nJ. Results in this paper show that tungsten diselenide can be applied to ultrafast optics, which is a kind of saturable absorption material with excellent properties.