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1

Error mitigation algorithm based on bidirectional fitting method for collision avoidance of Unmanned Surface Vehicle

Song L., Chen Z., Mao Y., Dong Z., Xiang Z.

Polish Maritime Research

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2018

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nr 4

13--20

EN

Radars and sensors are essential devices for an Unmanned Surface Vehicle (USV) to detect obstacles. Their precision has improved significantly in recent years with relatively accurate capability to locate obstacles. However, small detection errors in the estimation and prediction of trajectories of obstacles may cause serious problems in accuracy, thereby damaging the judgment of USV and affecting the effectiveness of collision avoidance. In this study, the effect of radar errors on the prediction accuracy of obstacle position is studied on the basis of the autoregressive prediction model. The cause of radar error is also analyzed. Subsequently, a bidirectional adaptive filtering algorithm based on polynomial fitting and particle swarm optimization is proposed to eliminate the observed errors in vertical and abscissa coordinates. Then, simulations of obstacle tracking and prediction are carried out, and the results show the validity of the algorithm. Finally, the method is used to simulate the collision avoidance of USV, and the results show the validity and reliability of the algorithm.

2

Mass transfer process of leaching weathered crust elution-deposited rare earth ore with magnesium salts

Chen Z., Zhang Z., He Z., Chi R.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 3

1004--1013

EN

In order to optimize the leaching process of weathered crust elution-deposited rare earth ore with magnesium salts, the influence of different flow rate, concentration of magnesium ions, initial pH of magnesium salts solution and experimental temperature on the mass transfer process of rare earth and aluminum was investigated in the case of using magnesium salts as leaching agent. The relationship between the flow rate μ and the HETP (Height Equivalent of Theoretical Plate) is in accordance with the Van Deemter equation when magnesium salts were used as leaching agent. The optimum condition for rare earth and aluminum were 0.4 cm3/min of flow rate and 0.2 mol/dm3 of magnesium ion concentration of magnesium sulfate, magnesium chloride and magnesium nitrate respectively. Under this condition the mass transfer efficiency of rare earth and aluminum with three kinds of magnesium salts follow the order of Mg(NO3)2>Mg(Cl)2>MgSO4. High temperature contributes to improving the mass transfer efficiency of rare earth and aluminum. Magnesium nitrate as the leaching agent can get the highest leaching mass transfer efficiency of rare earth and magnesium sulfate as the leaching agent can make the impurity leaching and mass transfer efficiency of Al is the lowest.

3

Influence of fenugreek-gum and particle size on performance of talc flotation

Gu G., Mo C., Zhao K., Chen Z., Wang X.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 3

1026--1033

EN

Talc usually exists as a gangue mineral in copper-nickel sulfide, molybdenite etc. In order to separate precious metals, naturally hydrophobic talc should be depressed effectively in flotation process. The effect of fenugreek-gum (FG) on the flotation performance of talc with different particle sizes was studied. The depression mechanism was investigated extensively through tests of flotation, adsorption and zeta potential, as well as infrared spectroscopy and laser particle size analysis. Flotation results indicated that the FG had a strong depression ability for talc with the particle size of -0.074 + 0.037 mm, -0.037 mm and -0.010 mm when proper dosage of FG was added. The coarse talc was completely depressed by 2.5 mg/ dm3 FG. When the particle size decreased, more FG was required to obtain the maximum depressing effect, which was verified by adsorption tests. FG reduced the electronegativity on the talc surface by chemical adsorption, and flocculation of talc powders caused a high efficient depressing effect.

4

Effect of modified starch on separation of fluorite from barite using sodium oleate

Chen Z., Ren Z., Gao H., Qian Y., Zheng R.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 2

228--237

EN

In this study, a modified starch was utilized to selectively separate barite from fluorite. The results of flotation tests showed that highly selective separation of fluorite from barite was obtained when 250 mg/dm3 of modified starch and 13.16×10−5 mol/dm3 sodium oleate was used in neutral solutions. FTIR spectra results showed that the modified starch can adsorb on the fluorite and barite surfaces. Zeta potential analyses indicated that the modified starch had little effect on adsorption of sodium oleate on the fluorite surface, although it interfered with the adsorption of sodium oleate on the barite surface. Contact angle measurements results corresponded well with the flotation results.

5

Contribution on fluid inclusion abundance to activation of quartz flotation

Yuan Y., Zhang L., Guan J., Zhang C., Wu J., Chen Z.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 3

981--991

EN

In this study, comparative experiments were conducted on the recovery of quartz using flotation with different fluid inclusion abundances. A large number of fluid inclusions with various sizes have been found in natural quartz. Micrographs, inductively coupled plasma, electron probe microanalysis, homogenization temperature, Raman spectra, zeta potentials, X-ray photoelectron spectroscopy, scanning electron microscope, and energy dispersive spectrometer were used to characterize the fluid inclusions and quartz, as well as the adsorption tests and single mineral flotation experiments to investigate its floatability. The results demonstrated that it was more likely for quartz with higher fluid inclusion abundance to connect with Fe3+ sufficiently to achieve a high level of flotation recovery, due to the powerful collecting ability by sodium dodecyl sulphonate to Fe3+. Furthermore, the mechanism indicated that the adsorption between quartz and Fe3+ was a process of chemisorption.

6

Computational fluid dynamics (CFD) numerical simulation and particle image velocimetry (PIV) measurement of a packed flotation column

Yan X., Chen Z., Wang L.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 2

395--405

EN

Packing is a useful method to obtain a static separation environment for a high flotation recovery and selectivity. In this study, the single-phase flow field in a packed lab-scale cyclonic-static microbubble flotation column (FCSMC) was investigated by computational fluid dynamics (CFD) simulation. Turbulence model was verified by Particle Image Velocimetry (PIV) experiment; the simulation results obtained by the RSM (Reynolds Stress Model) are closer to the experimental data. Based on this validation, RSM turbulence model was used to obtain the effect of sieve-plate on the hydrodynamic characteristics in the column flotation zone. The results show that the sieve-plate packing arrangement greatly straightens the rotation flow and decreases the turbulence. To further improve the effect of packing, two layers of sieve plates were used, and one diameter (1D = 190 mm) was selected as the reasonable distance between the two layers of sieve plates. To quantitative evaluate the effect of sieve-plate packing, the logarithm of Pdk over the logarithm of Pdo was calculated based on the volume-averaged turbulence dissipation rate, increasing from 24.72 for one layer of sieve-plate packing to 216.96 for two layers of sieve-plate packing. The probability of detachment significantly decreased for two layers of sieve-plate packing, and the recovery efficiency was significantly improved.

7

Tight focusing of radially polarized beams by a devil’s vortex lens

Chen Z., Hu X., Chen X., Wang X., Pu J.

Optica Applicata

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2018

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Vol. 48, nr 3

389--398

EN

Tight focusing of radially polarized beams with a devil’s vortex lens is numerically investigated. Multiple focal spots can be generated in the geometric focus when a radially polarized beam is focused by a high numerical aperture objective in the presence of a devil’s vortex lens. The position of the major focal spot shifts from the geometric focus when a devil’s vortex lens with S = 1 is employed, and the position of the focal spot can be controlled by the numerical aperture of the objective. The intensity components of the major focal spot are influenced by the vortex phase of the devil’s vortex lens. A strong longitudinal component near the optical axis is produced by a devil’s vortex lens without vortex phase, and a nearly pure transversal field is produced by a devil’s vortex lens with vortex phase.

8

Leaching of heavy metals from MSWI fly ash : experiments vs. simulation

Qiu Q, Jiang X., Chen Z., Lu S., Ni M.

Archives of Environmental Protection

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2018

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Vol. 44, no. 2

55--61

EN

In this work, pH-dependence experiments and leaching modeling using Visual MINTEQ were performed to evaluate the stability and simulate the leaching characteristics of heavy metals in municipal solid waste incineration (MSWI) fly ash. Modeling the equilibrium concentration of Cd, Cu, Cr, Ni, Pb and Zn in raw and treated fly ash was the main target and was conducted over a pH range of 0.5–14. In addition, simulation of the leaching behavior of MSWI fly ash with different additives was also conducted. The treated fly ash was solidified by a microwave-assisted hydrothermal process with added phosphate. The initial elemental concentrations of MSWI fly ash, including raw and treated fly ash, were detected by a microwave apparatus and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The ICP-AES analysis showed that most leaching concentrations of treated fly ash decreased considerably compared to the raw fly ash. The simulation results indicated that the dissolution/precipitation simulation models of Zn, Cu and Pb were broadly consistent with the experimental results, while the leaching behaviors of Ni, Cr and Cd were determined by both dissolution/precipitation and surface complexation mechanisms. In addition, the models of reagent solidification revealed that the stabilization effect of Na2S was better than that of Na2CO3. This model will be useful in the evaluation of the leaching concentrations of heavy metals in fly ash.

9

Engineering example of the constraint forces in non-holonomic mechanical: forklift-truck robot motion. Part I

Haddout S., Guennoun M. A., Chen Z.

Archives of Control Sciences

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2018

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Vol. 28, No. 3

483--506

EN

In the presented paper, a problem of nonholonomic constrained mechanical systems is treated. New methods in nonholonomic mechanics are applied to a problem of a Forklift-truck robot motion. This method of the geometrical theory of general nonholonomic constrained systems on fibered manifolds and their jet prolongations, based on so-called Chetaev-type constraint forces. The relevance of this theory for general types of nonholonomic constraints, not only linear or affine ones, was then verified on appropriate models. On the other hand, the equations of motion of a Forklift-truck robot are highly nonlinear and rolling without slipping condition can only be expressed by nonholonomic constraint equations. In this paper, the geometrical theory is applied to the above mentioned mechanical problem. The results of numerical solutions of constrained equations of motion, derived within the theory, are presented.

10

The role of powder layer thickness on the quality of SLM printed parts

Nguyen Q. B., Luu D. N., Nai S. M. L., Zhu Z., Chen Z., Wei J.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 3

948--955

EN

Achieving good mechanical properties as well as the dimensional accuracy and the smooth surface quality of selective laser melting printed parts with minimal post treatments are essential in additive manufacturing. In the present study, Inconel 718 samples with different powder layer thickness (20, 30, 40 and 50 μm) were additively fabricated using 3D Systems ProX-300 machine. The results reveal that the lower the layer thickness, the denser and good dimensional accuracy were achieved. Marginally higher mechanical properties and microhardness were also obtained at the lower thickness while the failure strain was still high. This can be explained through significant change in the microstructure due to different cooling rate and thermal cycles. In addition, the formation of ɤ′ and ɤ″ intermetallic phases, which were well distributed in the matrix and grain boundaries, during heating/cooling, gave rise in the strengths. Fractography shows the plastic deformation band due to work hardening and the crack initiation sites at sub-micro/micro pores, lack of fusion areas and the boundary of unmelted particles. The study would guide engineers balance their options between the production rate and the building parts’ quality.

11

Biomechanical evaluation of tendon connection with novel suture techniques

Chen Z., Wang J., Wei J.- S., Hou Z.-Y., Li M., Chen Q.-X

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 1

135--141

EN

Achilles tendon rupture is a severe injury with poor curative effect due to its anatomical characteristic and mechanical peculiarity. Internal fixation of limited loop (IFLL) with steel-wire has been applied on patients with tendon rupture to fix the broken ends before physical rehabilitation. The purpose of this study is to investigate the biomechanical property and radiological characteristic of such suture technique for the repairment of tendon rupture. Methods: Tendons of pigs’ hint feet were separated for the biomechanical study. Suture surgery was performed according to the protocol of IFLL. Biomechanical Testing Machine was adopted to conduct the biomechanical tensile load examination. The maximal load, elastic modulus and tendon stiffness of the stitched tendons with or without reinforcement were examined. Results: The maximum tensile load of the stitched tendons using IFLL reached 1/4 of the uninjured tendon’s maximum tensile load, indicating that such suture technique is capable of providing enough tension for the ruptured tendon. Surprisingly, tendons fixed with titanium wire showed the highest load tension, which was comparable to the undamaged tendon. Therefore, we found the biomechanical basis of using IFLL in effectively connecting the rupture ends of tendons. Conclusions: In conclusion, we provide biomechanical evidence for the use of IFLL in treatment of Achilles tendon rupture, by providing enough strength for the ankle function. Such suture technique could help the patients with better rehabilitation and reduced in-hospital stay after Achilles tendon injury.

12

Multiresidue determination of antibiotics in preserved eggs using a QuEChERS-based procedure by ultrahigh-performance liquid chromatography tandem mass spectrometry

Li Y., Chen Z., Wen S., Hou X., Zhang R., Ma M.

Acta Chromatographica

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2018

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Vol. 30, no. 1

9--16

EN

A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method and ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC–MS/MS) were optimized and validated for 16 antibiotics belonging to three families (macrolides, quinolones, and sulfonamides) that were found in preserved eggs. Samples were extracted in 4 mL water and 10 mL acetonitrile with 1% acetic acid and subjected to a cleanup procedure using dispersive solid-phase extraction with C18 and primary secondary amine sorbents, prior to detection by UHPLC–MS/MS. Matrix-matched calibration was used for quantification to reduce the matrix effect with limits of quantification in the range of 0.3–3.0 μg/kg. Validation of the method was conducted by recovery and precision experiments. Recoveries of the spiked samples ranged from 73.8% to 127.4%, and the intra- and inter-day relative standard deviations were lower than 21.2% and 22.3%, respectively. This method was successfully applied to the analysis of antibiotics in preserved egg samples.

13

Diatom stratigraphy of FA-1 core, Qarun Lake, records of Holocene environmental and climatic change in Faiyum Oasis, Egypt

Zalat A. A., Marks L., Welc F., Salem A., Nitychoruk J., Chen Z., Majecka A., Szymanek M., Chodyka M., Tołoczko-Pasek A., Sun Q. L., Zhao X., Jiang J.

Studia Quaternaria

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2017

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Vol. 34, Nr 1

61--69

EN

This study evaluates changes in the environmental and climatic conditions in the Faiyum Oasis during the Holocene based on diatom analyses of the sediment FA-1 core from the southern seashore of the Qarun Lake. The studied FA-1 core was 26 m long and covered the time span ca. 9.000 cal. yrs BP. Diatom taxa were abundant and moderately to well-preserved throughout the core sediments. Planktonic taxa were most abundant than the benthic and epiphytic forms, which were very rare and sparsely distributed. The most dominant planktonic genera were Aulacoseira and Stephanodiscus followed by frequently distribution of Cyclostephanos and Cyclotella species. The stratigraphic distribution patterns of the recorded diatoms through the Holocene sediments explained five ecological diatom groups. Thesegroups represent distinctive environmental conditions, which were mainly related to climatic changes through the earlyand middle Holocene, in addition to anthropogenic activity during the late Holocene. Comparison of diatom assemblages in the studied sediment core suggests that considerable changes occurred in water level as well as salinity. There were several high stands of the freshwater lake level during humid, warmer-wet climatic phases marked by dominance of planktonic, oligohalobous and alkaliphilous diatoms alternated with lowering of the lake level and slight increases in salinity and alkalinity during warm arid conditions evident by prevalence of brackish water diatoms.

14

Preparation of activated bentonite and its adsorption behavior on oil-soluble green pigment

Zheng R., Gao H., Ren Z., Cen D., Chen Z.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

829--845

EN

The present research work focuses on effective preparation of activated bentonite (AB) and its application in removal of oil-soluble green pigment (OSGP) from either vegetable oils or food-processing wastewater. Mono-factor experiments were carried out to explore the effects of operation factors in preparation of AB. The parameters investigated were the effect of contact time, adsorbent dosage, initial OSGP concentration and temperature. The chemical composition, crystalline phases, microstructure and functional groups of prepared AB were characterized and evaluated by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The adsorption kinetics and equilibrium isotherms were studied, finding that the adsorption process fitted better with the pseudo-second-order model and the Freundlich isotherm equation. In addition, thermodynamic parameters, such as standard the Gibbs free energy (ΔG°), standard enthalpy (ΔH°) and standard entropy (ΔS°) were also calculated, indicating that adsorption was spontaneous and endothermic. The findings of this investigation suggest that AB prepared through microwave activation as a cheap adsorbent holds great potential to remove oil-soluble green pigment in the wastewater treatment process.

15

Coating of LiBH4 and Its Effect on the Decomposition of RDX and AP

Ding X., Shu Y., Chen Z., Liu N., Gou B., Zhang J., Wu M., Xie G., Dang T.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 1

134--151

EN

The novel fuel additive LiBH4 was introduced as an energetic component for its outstanding hydrogen content, perfect burning performance and high reactivity. In order to limit the hygroscopicity and to improve the stability in the air, LiBH4 was coated on the surface with wax and polyester carbonate. The final product was characterized by scanning electron microscopy (SEM), X-ray photoelectron energy spectroscopy (XPS) and Raman spectroscopy, while the stability in air was investigated by regular checking of variations in weight. The results show that a uniform coating layer was formed on the surface of the LiBH4, and the coverage was estimated from the boron content as approximately 82%. A healing effect was confirmed on defective surfaces exposed to air; the coating layer improves the relative stability by 50.7%. Furthermore, LiBH4 as an additive to promote the thermal decomposition of 1,3,5-trinitro-1,3,5-trazinane (RDX) and ammonium perchlorate (AP) was explored by differential scanning calorimetry (DSC), in which the catalytic effects of pure LiBH4 and coated LiBH4 were compared, and indicated that the coating does not decrease the reactivity of LiBH4. It is suggested that surface coating with some inert materials is a simple and effective method for improving the storage and performance of LiBH4, while ensuring its reactivity.

16

Comparative investigations of nonlinear and linear observers for a highly manoeuvrable target in sliding mode guidance

Wang Y., Sun M., Du S., Chen Z.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2017

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Vol. 65, nr 2

233--245

EN

Target manoeuvre is one of the key factors affecting guidance accuracy. To intercept highly maneuverable targets, a second-order sliding-mode guidance law, which is based on the super-twisting algorithm, is designed without depending on any information about the target motion. In the designed guidance system, the target estimator plays an essential role. Besides the existing higher-order sliding-mode observer (HOSMO), a first-order linear observer (FOLO) is also proposed to estimate the target manoeuvre, and this is the major contribution of this paper. The closed-loop guidance system can be guaranteed to be uniformly ultimately bounded (UUB) in the presence of the FOLO. The comparative simulations are carried out to investigate the overall performance resulting from these two categories of observers. The results show that the guidance law with the proposed linear observer can achieve better comprehensive criteria for the amplitude of normalised acceleration and elevator deflection requirements. The reasons for the different levels of performance of these two observer-based methods are thoroughly investigated.

17

A seismic interpolation and denoising method with curvelet transform matching filter

Yang H., Long Y., Lin J., Zhang F., Chen Z.

Acta Geophysica

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2017

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Vol. 65, no. 5

1029--1042

EN

A new seismic interpolation and denoising method with a curvelet transform matching filter, employing the fast iterative shrinkage thresholding algorithm (FISTA), is proposed. The approach treats the matching filter, seismic interpolation, and denoising all as the same inverse problem using an inversion iteration algorithm. The curvelet transform has a high sparseness and is useful for separating signal from noise, meaning that it can accurately solve the matching problem using FISTA. When applying the new method to a synthetic noisy data sets and a data sets with missing traces, the optimum matching result is obtained, noise is greatly suppressed, missing seismic data are filled by interpolation, and the waveform is highly consistent. We then verified the method by applying it to real data, yielding satisfactory results. The results show that the method can reconstruct missing traces in the case of low SNR (signal-to-noise ratio). The above three problems can be simultaneously solved via FISTA algorithm, and it will not only increase the processing efficiency but also improve SNR of the seismic data.

18

Preliminary report on unique laminated Holocene sediments from the Qarun Lake in Egypt

Marks L., Salem A., Welc F., Nitychoruk J., Chen Z., Zalat A., Majecka A., Chodyka M., Szymanek M., Tołoczko-Pasek A.

Studia Quaternaria

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2016

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Vol. 33, Nr 1

35--46

EN

The Lake Qarun (Faiyum Oasis, northern Egypt) is a relic of the much larger Holocene lake. Past lake levels and extensions were reconstructed, based on setting of archaeological sites scattered along northern paleoshores of the ancient lake. However, geoarcheological works did not yield enough data to establish continuous environmental history of the lake. A deep drilling FA-1 on the southeastern shore of the lake, performed in 2014, supplied with a core, 26 m long that is the one of the longest lake sediment cores in northeastern Africa. The basal section of the core consisted of thin-laminated diatom marly deposits, underlain at the Late Pleistocene/Holocene boundary by coarse-grained sands. The sediment lamine were quite well developed, especially in the lower part of the core. Preliminary results indicated annually deposited sediment sequence with seasonality signals provided by microlamine of diatoms, calcite, organic matter and clastic material. Early Holocene varved sediments from the Faiyum Oasis supplied with exceptional paleoenvironmental data for northeastern Africa, which enriched a record from previous logs drilled at the southwestern margin of the Qarun Lake.

19

Three Dimensional Crustal Density Structure of Central Asia and its Geological Implications

Yang W., Chen Z., Hou Z., Yu C.

Acta Geophysica

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2016

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Vol. 64, no. 5

1257--1274

EN

This paper introduces the scale-depth law of multi-scale wavelet analysis for regional gravity data processing, and presents the results of its application to Central Asia for computation of the 3D crustal density structures. The wavelet analysis method is applied for characterizing 3D crustal density structure, producing five maps of density disturbance corresponding to different depths of equivalent layers in the crust. The results provide important evidence for the study of crustal structures and mass movement in Central Asia: (i) the small-scale and intensive linear density disturbances in the upper crust indicate Phanerozoic orogenic belts; (ii) there exists a horseshoe-shaped low-density belt in the middle crust coinciding with the Kazakhstan orocline; (iii) there is a very low density zone in the lower crust, extending from western Kunlun to Tianshan, probably indicating a lower-crust flow; (iv) there are a few lowdensity spots in the middle crust, which might be caused by low-density mass squeezing upward from the lower crust flows.

20

Surfactant assisted removal of engine oil from synthetic soil

Ramamurthy A. S., Chen Z., Li X., Azmal M.

Environment Protection Engineering

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2015

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Vol. 41, nr 2

67--79

EN

Effectiveness of surfactants SDS (sodium dodecyl sulfate), AOT (sodium dioctyl sulfosuccinate) and Brij 35 (polyoxyethylene lauryl ether) in removing residual oil from soils have been determined. Experimental results indicated that oil desorption efficiencies with surfactants are 7 to 18 times higher than using water alone. 0.6% Brij 35 at was the most effective surfactant to remove oil from soil, and it did not display any significant change in oil desorption with pH changes. A comparison study also showed that pore volume was a more significant parameter than soil washing flow rate to improve oil desorption.