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1

The Machine Learning Method of PIDVCA

Li L., Wang X., Chen G.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2020

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Vol. 14. no. 3

533--540

EN

Building a dynamic collision knowledge base of self-learning is one of the core contents of implementing "personified intelligence" in Personifying Intelligent Decision-making for Vessel Collision Avoidance (short for PIDVCA). In the paper, the machine learning method of PIDVCA combined with offline artificial learning and online machine learning is proposed. The static collision avoidance knowledge is acquired through offline artificial learning, and the isomeric knowledge representation integration method with process knowledge as the carrier is established, and the Dynamic collision avoidance knowledge is acquired through online machine learning guided by inference engine. A large number of simulation results show that the dynamic collision avoidance knowledge base constructed by machine learning can achieve the effect of anthropomorphic intelligent collision avoidance. It is verified by examples that the machine learning method of PIDVCA can realize target perception, target cognition and finally obtain an effective collision avoidance decision-making.

2

The effect of high ship speed ratio on collision avoidance behavior of COLREGS

Wang X. H., Li L., Chen G.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2019

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Vol. 13, no. 2

319--323

EN

The speed ratio is an important factor that must be considered when two vessels will course change to avoid collision. In the process of the research on Personifying Intelligent Decision-making for Vessel Collision Avoidance (short for PIDVCA), it is found that the effect of collision avoidance based on the existing “International Regulations for Prevention Collision at sea” (short for COLREGS) is greatly affected by the high speed ratio (k=Vt/V0≥1.5). Through the analysis on the geometric change law of two vessels’ relative motion in Open waters, the effects of the responsibility for the ship collision avoidance under the COLREGS and special case for high-speed ratio is discussed. According to the collision avoidance measures taken for two vessels encounter situation, some reasonable suggestions are put forward and the simulation experiments that based on ship's intelligent collision avoidance simulation platform are given to support the idea.

3

A novel method to extract vanadium from vanadium-bearing steel slag using sodium carbonate solution

Gao M., Xue X., Li L., Yang H., Bai R., Wang H.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 3

911--921

EN

A new method using sodium carbonate solution to treat a vanadium-bearing steel slag is proposed. The effects of the particle size, solid-to-liquid ratio, initial concentration of sodium carbonate solution, leaching temperature and stirring speed on the leaching rate of vanadium were investigated. The leaching kinetics of vanadium from the vanadium-bearing steel slag was studied, which indicated that the leaching rate was controlled by the step of diffusion through the solid layer around the unreacted core. The apparent activation energy for the process was 13.75 kJ/mol. By using this process, vanadium could be extracted effectively with the leaching rate of more than 80%.

4

Synthesis, sintering, specific heat and magnetism of Eu3S4 by low-temperature CS2-gas sulfurization of Eu2O3 nanospheres

Chen Y., Li L., Hirai S.

Materials Science Poland

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2018

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Vol. 36, No. 4

616--622

EN

Single-phase Eu3S4 was obtained via CS2 gas sulfurization of Eu2O3 nanospheres at 773 K for longer than 0.5 h. The primary particle size of Eu3S4 became larger than that of Eu2O3 during the sulfurization process. Pure synthetic Eu3S4 powders were unstable and transformed to EuS at 873 K under vacuum. Eu3S4 compacts were sintered in temperature range of 773 K to 1173 K and they transformed to EuS at 1473 K during spark plasma sintering. Specific heat of sintered Eu3S4did not show an anomalous behavior in the range of 2 K to 50 K. The magnetic susceptibility of polycrystalline Eu3S4 followed a Curie-Weiss law from 2 K to 300 K. Magnetization of polycrystalline Eu3S4 was larger than that of single crystal Eu3S4 when the magnetic field was less than 3.5 kOe.

5

Study on the Rotor Spinning Technology of Cotton Stalk Bark Fibers/Cotton Fibers

Li L., Liu L., Qin C.

Fibres & Textiles in Eastern Europe

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2018

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Vol. 26, no. 6 (132)

68--70

EN

The length difference and low flexibility of cotton stalk bark fibers make fiber spinning difficult. In this work, cotton stalk bark fibers that were directly from degummed cotton stalk bark were wetted, carded and softened before sliver-marking, and then they were blended with cotton fibers for carding and spinning in various blending ratios. The results showed that a reasonable open roller speed was 6000 rpm for blending ratio 50/50, 7000 rpm for blending ratio 35/65, and 8000 rpm for blending ratio 20/80. The minimum yarn linear density was 60 tex for blending ratio 50/50, 50 tex for blending ratio 35/65, and 40 tex for blending ratio 20/80.

PL

Różnica długości i niska elastyczność włókien z kory szypułkowej bawełny utrudniają przędzenie włókien. W pracy, włókna z kory szypułkowej bawełny, które były bezpośrednio odśluzowane z bawełnianej szypułki, zwilżono i zmiękczono, a póżniej zmieszano z włóknami bawełnianymi następnie zgrzeblono i przędzono w różnych stosunkach mieszania. Wyniki wykazały, że optymalna prędkość wynosiła 6.000 obrotów/minutę dla stosunku mieszania 50/50, 7.000 obrotów/minutę dla stosunku mieszania 35/65 i 8.000 obrotów na minutę dla stosunku mieszania 20/80. Minimalna gęstość liniowa przędzy wynosił i czystej bawełnya 60 tex dla stosunku mieszania 50/50, 50 tex dla stosunku mieszania 35/65 i 40 tex dla stosunku mieszania 20/80.

6

Comparison of the Structure and Properties of Wool and Cashmere Fibrrs under Potassium Permanganate Treatment

Li L., Qin C., Liu C.

Fibres & Textiles in Eastern Europe

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2018

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Vol. 26, no. 4 (130)

29--33

EN

In this study, the weight loss and tensile property of wool fibers and cashmere fibers before and after various potassium permanganate solution treatment were investigated. The scale morphology andcrystallization index of the original and treated fibers were analysed with scanning electron microscopy and X-ray diffraction analysis. The experimental results showed that the weight loss of wool fibers is more than that of cashmere fibers under low potassium permanganate content treatment, but is less than that of cashmere fibers under high potassium permanganate content treatment. The force loss of cashmere fibers increased linearly with an increase in potassium permanganate content. The scales of cashmere fiber were damaged at a potassium permanganate content of 9%, but the scales of wool fiber were clear. The relative crystallisation index of treated wool is twice as that of treated cashmere at a potassium permanganate content of 9%.

PL

W pracy zbadano utratę masy i wytrzymałość na rozciąganie włókien wełnianych i kaszmirowych przed i po zastosowaniu różnych roztworów nadmanganianu potasu. Morfologię i wskaźnik krystalizacji pierwotnych i poddanych obróbce włókien analizowano za pomocą skaningowej mikroskopii elektronowej i dyfrakcji rentgenowskiej. Wyniki eksperymentalne wykazały, że ubytek masy włókien wełnianych jest większy, niż w przypadku włókien kaszmirowych po zastosowaniu obróbki nadmanganianem potasu. Utrata wytrzymałości włókien kaszmirowych wzrastała liniowo wraz ze wzrostem zawartości nadmanganianu potasu. Stwierdzono, że względny wskaźnik krystalizacji wełny poddanej obróbce jest dwukrotnie większy, niż w przypadku kaszmiru poddanego obróbce przy zawartości nadmanganianu potasu wynoszącej 9%.

7

Minimum dispersion coefficient criteria based positioning algorithm for BDS

Wang L., Li L.

Archives of Electrical Engineering

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2018

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Vol. 67, nr 4

739--753

EN

The BeiDou navigation satellite system (BDS) is one of the four global navigation satellite systems. More attention has been paid to the positioning algorithm of the BDS. Based on the study on the Kalman filter (KF) algorithm, this paper proposed a novel algorithm for the BDS, named as the minimum dispersion coefficient criteria Kalman filter (MDCCKF) positioning algorithm. The MDCCKF algorithm adopts minimum dispersion coefficient criteria (MDCC) to remove the influence of noise with an alpha-stable distribution (ASD) model which can describe non-Gaussian noise effectively, especially for the pulse noise in positioning. By minimizing the dispersion coefficient of the positioning error, the MDCCKF assures positioning accuracy under both Gaussian and non-Gaussian environment. Compared with the original KF algorithm, it is shown that the MDCCKF algorithm has higher positioning accuracy and robustness. The MDCCKF algorithm provides insightful results for potential future research.

8

Some q-rung orthopair linguistic Heronian mean operators with their application to multi-attribute group decision making

Li L., Zhang R., Shang X.

Archives of Control Sciences

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2018

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Vol. 28, No. 4

551--583

EN

The recently proposed q-rung orthopair fuzzy set (q-ROFS) characterized by a membership degree and a non-membership degree is powerful tool for handling uncertainty and vagueness. This paper proposes the concept of q-rung orthopair linguistic set (q-ROLS) by combining the linguistic term sets with q-ROFSs. There after, we investigate multi-attribute group decision making (MAGDM) with q-rung orthopair linguistic information. To aggregate q-rung orthopair linguistic numbers (q-ROLNs), we extend the Heronian mean (HM) to q-ROLSs and propose a family of q-rung orthopair linguistic Heronian mean operators, such as the q-rung orthopair linguistic Heronian mean (q-ROLHM) operator, the q-rung orthopair linguistic weighted Heronian mean (q-ROLWHM) operator, the q-rung orthopair linguistic geometric Heronian mean (q-ROLGHM) operator and the q-rung orthopair linguistic weighted geometric Heronian mean (q-ROLWGHM) operator. Some desirable properties and special cases of the proposed operators are discussed. Further, we develop a novel approach to MAGDM within q-rung orthopair linguistic context based on the proposed operators. A numerical instance is provided to demonstrate the effectiveness and superiorities of the proposed method.

9

Experimental study of low cycle fatigue properties for epoxy resins with dibutyl phthalate (DBP)

Wang Z., Zhou J., Song L., Li L.

Archives of Civil Engineering

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2018

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Vol. 64, nr 2

147--159

EN

In order to improve the toughness of traditional epoxy resin, dibutyl phthalate (DBP) was introduced into the epoxy resin. The static mechanical performance of plasticized and unplasticized epoxy resin was evaluated. The test results showed that the DBP modified epoxy resin can obtain a higher toughness than conventional epoxy resin, but the elastic modulus and the tensile strength were slightly reduced. The low cycle fatigue test results indicated that the stress ratio and the stress level were two critical factors of fatigue life, which was increased with the growth of stress ratio. It was also found that the fatigue life of plasticized specimen was much less than that of the unplasticized specimen because of the plastic deformation. A logarithmic linear relationship was then established to predict the fatigue life for plasticized epoxy resin. The strain energy density was also applied to demonstrate the accumulation of energy loss. In addition, the fatigue toughness can be obtained by the hysteresis loop area method.

PL

W artykule przedstawiono właściwości zmęczeniowe żywicy plastyfikowanej z ftalanem dibutylu (DBP) oraz niemodyfikowanej żywicy epoksydowej. W celu zwiększenia wytrzymałości tradycyjnej żywicy epoksydowej, do źywicy epoksydowej wprowadzono ftalan dibutylu (DBP). Oceniono statyczną wytrzymałość mechaniczną plastyfikowanej oraz nieplastyfikowanej żywicy epoksydowej. Wyniki badania wykazały, że wydłużenie plastyfikowanej oraz nieplastyfikowanej żywicy wynosi odpowiednio 4,61% i 3,55%, co oznacza, że modyfikowana żywica epoksydowa z ftalanem dibutylu (DBP) może uzyskać wyższą wytrzymałość niż zwykła żywica epoksydowa. Jednakże moduł sprężystości i wytrzymałość na rozciąganie plastyfikowanej żywicy zostały nieznacznie zmniejszone. Niskocyklowe badanie zmęczeniowe w trzech różnych współczynnikach oraz poziomach naprężenia przeprowadzono w celu porównania wytrzymałości zmęczeniowej żywicy epoksydowej. Wyniki badania wykazały, że współczynnik oraz poziom naprężenia stanowiły dwa krytyczne czynniki trwałości zmęczeniowej, która została zwiększona wraz ze wzrostem współczynnika naprężenia. Stwierdzono również, że trwałość zmęczeniowa plastyfikowanej próbki była znacznie mniejsza niż w przypadku nieplastyfikowanej próbki z powodu odkształcenia plastycznego. Następnie ustalono logarytmiczną zależność liniową, aby przewidzieć trwałość zmęczeniową plastyfikowanej żywicy epoksydowej. Gęstość energii odkształcenia została również zastosowana w celu wykazania nagromadzenia strat energii. Ponadto wytrzymałość zmęczeniową można uzyskać za pomocą metody pola pętli histerezy. Obszar pętli histerezy oraz odpowiednia gęstość energii odkształcenia maleją wraz ze wzrostem współczynnika naprężenia zarówno dla plastyfikowanej i nieplastyfikowanej żywicy. Gęstość energii odkształcenia plastyfikowanej żywicy jest większa niż gęstość nieplastyfikowanej żywicy dla tego samego współczynnika naprężenia. Analiza szkód zmęczeniowych przy użyciu pętli histerezy może być uważana za jedną ze skutecznych metod dla żywicy.

10

Effect of activated carbon on methomyl poisoning by urine metabolomics base on gas chromatography–mass spectrometry

Li L., Hu L., Chen B., Dong Y., Lin Z., Wang Z., Wen C., Wang X., Wang S.

Acta Chromatographica

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2018

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Vol. 30, no. 1

21--25

EN

In this study, we developed a urine metabolomic method by gas chromatography–mass spectrometry (GC–MS) combination with biomedical results to evaluate the effect of activated carbon on methomyl poisoning rats. The rats were divided into four groups, methomyl group, two activated carbon treatment group, and control group. According to the biochemical results, it indicated that activated carbon treated rats could cause liver and kidney function changes. According to the urine metabolomics results, activated carbon treatment group (10 min) and activated carbon treatment group (30 min) could be distinguished from methomyl group, and activated carbon treatment group (10 min) could be separated from activated carbon treatment group (30 min) rats, which indicated that the treatment of rats by activated carbon in different time had a different effect. The results indicate that metabolomic method by GC–MS may be useful to elucidate activated carbon treated on methomyl poisoning rats.

11

Selective agglomeration of magnetite in entlandite-serpentine system and implication for their separation

Lu J., Yuan Z., Liu J., Li L., Wang N., Meng Q.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

943--955

EN

In nickel sulfide processing, magnesium silicates (serpentines) can easily form slime coatings or hetero-aggregation on pentlandite surfaces, and hence decrease the pentlandite flotation rate and recovery. In this work, magnetic separation of pentlandite from serpentine using selective magnetic coating through adding magnetite fines as magnetic seeds was investigated. Interactions of magnetite-pentlandite and magnetite-serpentine were calculated by the DLVO (Derjaguin-Landau-Verwey-Overbeek) theory. The results show that the interaction of magnetite-pentlandite was obviously stronger than that of magnetite-serpentine with an external weak magnetic field (4776 A/m-1). Therefore, fine magnetite fractions selectively adhered to the pentlandite surfaces and enhanced its magnetism, resulting in being separated from serpentine by magnetic separation, which was further verified by magnetic coating-magnetic separation and SEM observations.

12

Flotation of molybdenite in the presence of microemulsified collector

You X., Li L., Lyu X.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 1

333--341

EN

In this paper molybdenite flotation using microemulsified collector was reported. The flotation performance of microemulsified collector and conventional diesel was compared. This study is a prelimi-nary investigation which uses pure molybdenite mineral in a modified Hallimond tube. The pH tests showed that the highest recovery of molybdenite in the presence of diesel and microemulsion was ob-tained at pH=6, reaching the recoveries of 93% and 90%, respectively. In the case of obtaining similar results, it was observed that the microemulsion consumption was lower in comparison to diesel. In the flotation tests with microemulsified collector the recovery slightly decreased because too large collector amount caused formation of more unstable bubbles. The contact angle measurements showed that the microemulsified collector was more effective for increasing the hydrophobicity of molybdenite surface. An adsorption model was proposed and it was suggested that the non-ionic surfactant present in the mi-croemulsified collector formed a continuous bimolecular layer, resulting in the increased surface hydro-phobicity. The accomplishment of this research demonstrated the viability of the use of microemulsified collector in molybdenite flotation, attempting to simplify the molybdenite flotation process, especially replace the conventional emulsified collector with high energy consumption and difficult storage.

13

Numerical analysis of the factors affecting the anti-slide pile design

Tang Y., Xie Q., Gou W., Wan R., Li L.

Engineering Transactions

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2017

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Vol. 65, iss. 2

335--350

EN

The use of anti-slide piles is one of the most important landslide remediation methods, and it is widely used in practical engineering. Anti-slide pile design elements include pile plane position and spacing, the anchorage depth, and pile cross-sectional shape and size. With the displacement of an anti-slide pile head as the evaluation index of the anti-sliding effect of antislide pile, ANSYS was used to establish models for numerical simulation to provide analysis of the pile spacing and to determine the anchoring depth and cross- sectional dimensions of the impact of pile top displacement. Using the control variable method, the influence trends and the degree of influence of three factors on the displacement of pile top were studied. Through this analysis, we found that the influence of the pile cross-section size change on the maximum displacement of the pile head is relatively weak, whereas the anchoring depth and pile spacing have a greater impact on the changes in the maximum displacement of the pile; there is a limit of the design parameters, beyond which improvement in the design value is not obvious regarding the limiting of the displacement of the pile top. Further study could investigate the choice of design parameters to optimize the design of anti-slide pile.

14

Change characteristics of DSi and nutrition structure at the Yangtze River Estuary after Three Gorges Project impounding and their ecological effect

Li L., Shen X., Jiang M.

Archives of Environmental Protection

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2017

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Vol. 43, no. 2

74--79

EN

The variation law of dissolved silica (DSi), dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and nutrition structure after the Three Gorges Project (TGP) impounding as well as their ecological effect were analyzed according to monitoring survey of the Yangtze River Estuary in spring (May) and summer (August) from 2004–2009. The results showed that after impounding, DSi and DIN concentration decreased and increased, respectively. During the study period, DSi decreased by about 63%, while DIN almost tripled. DIP concentration fluctuated slightly. With respect to nutrition structure, N:P increased, whereas Si:P and Si:N declined. According to chemometry standard of nutrient limits, nutrition structure tended to be imbalanced and the limiting factor of phytoplankton growth (P) was studied. Changes of nutrition structure have largely decreased diatom and caused different composition of dominant phytoplankton species. This may change ecosystem structure of the Yangtze River Estuary.

15

Fracture mechanical properties of rock-like materials under half symmetric loading

Wang Z., Zhou J., Li L.

Archives of Civil Engineering

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2017

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Vol. 63, nr 4

71--82

EN

The authors studied the fracture mechanical properties under half-symmetric loading in this paper. The stress distribution around the crack tip and the stress intensity factor of three kinds of notched specimens under half symmetric loading were compared. The maximum tensile stress σmax of double notch specimens was much greater than that of single notch specimens and the maximum shear stress τmax was almost equal, which means that the single notch specimens were more prone to Mode II fractures. The intensity factors KII of central notch specimens were very small compared with other specimens and they induced Mode I fractures. For both double notch and single notch specimens, KII was kept at a constant level and did not change with the change of a/h, and KII was much larger than KI. KII has the potential to reach its fracture toughness KIIC before KI and Mode II fractures occurred. Rock-like materials were introduced to produce single notch specimens. Test results show that the crack had been initiated at the crack tip and propagated along the original notch face, and a Mode II fracture occurred. There was no relationship between the peak load and the original notch length. The average value of KIIC was about 0.602 MPa×m1/2, and KIIC was about 3.8 times KIC. The half symmetric loading test of single notch specimens was one of the most effective methods to obtain a true Mode II fracture and determine Mode fracture toughness.

PL

W niniejszej pracy przedstawiono właściwości mechaniczne pękania materiałów skalnych pod półsymetrycznym obciążeniem, w wyniku połączenia analizy teoretycznej, symulacji numerycznych oraz badań eksperymentalnych. W celu ujawnienia mechanizmu uszkodzenia, przygotowano trzy rodzaje próbek z karbem pod półsymetrycznym obciążeniem i zbadano rozkład naprężeń wokół pęknięcia podczas procesu obciążenia. Przyjęto metodę integralnej interakcji oprogramowania elementów skończonych ANSYS w celu obliczenia współczynnika intensywności naprężenia (SIF). Ponadto, wprowadzono pojedynczy element pęknięcia oraz element płaszczyzny 183 w strefie bez pęknięć. Zgodnie z analizą numeryczną i wynikami badań eksperymentalnych, maksymalne naprężenie rozciągające podwójnych próbek z karbem okazało się znacznie większe niż w przypadku pojedynczych próbek z karbem, a ich maksymalne naprężenie ścinające było prawie takie samo, co oznacza, że pojedyncze próbki z karbem były bardziej podatne na pęknięcie w trybie II. Współczynniki intensywności KII środkowych próbek z karbem były bardzo niskie w porównaniu z innymi próbkami oraz tymi, które wywoływały pęknięcia w trybie I. Zarówno w przypadku próbek z podwójnym i pojedynczym karbem, KII zostało utrzymane na stałym poziomie i nie uległo zmianie wraz ze zmianą a/h, a ponadto KII było znacznie większe niż KI. KII może potencjalnie osiągać odporność na kruche pękanie KIIC przed KI. W rezultacie mamy do czynienia z pęknięciami w trybie II. Wprowadzono materiały skalne w celu wytworzenia próbek z pojedynczym karbem. Pęknięcie rozpoczęło się na samej górze i rozprzestrzeniało się wzdłuż pierwotnej powierzchni karbu, w wyniku czego wystąpiło pęknięcie w trybie II. Nie zaobserwowano zależności pomiędzy szczytowym obciążeniem i oryginalną długością karbu. Średnia wartość KIIC była około 3,8 razy większa niż wartość KIC. Pęknięcia w górnej części były znacznie większe niż w innym miejscu, co oznacza, że koncentracja naprężeń pęknięcia w górnej części była oczywista, co z kolei może prowadzić do pęknięcia. Kąt maksymalnego głównego naprężenia wyniósł około 30°, co było zgodne z pęknięciem w trybie I w warunkach czystego obciążenia ścinającego. Badanie półsymetrycznego obciążenia próbek z pojedynczym karbem okazało się być jedną z najskuteczniejszych metod uzyskiwania prawdziwego pęknięcia w trybie II i określenia odporności na kruche pękanie.

16

A Coupled Smoothed Finite Element-Boundary Element Method for Structural-Acoustic Analysis of Shell

Tian W., Yao L., Li L.

Archives of Acoustics

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2017

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Vol. 42, No. 1

49--59

EN

Nowadays, the finite element method (FEM) – boundary element method (BEM) is used to predict the performance of structural-acoustic problem, i.e. the frequency response analysis, modal analysis. The accuracy of conventional FEM/BEM for structural-acoustic problems strongly depends on the size of the mesh, element quality, etc. As element size gets greater and distortion gets severer, the deviation of high frequency problem is also clear. In order to improve the accuracy of structural-acoustic problem, a smoothed finite-element/boundary-element coupling procedure (SFEM/BEM) is extended to analyze the structural-acoustic problem consisting of a shell structure interacting with the cavity in this paper, in which the SFEM and boundary element method (BEM) models are used to simulate the structure and the fluid, respectively. The governing equations of the structural-acoustic problems are established by coupling the SFEM for the structure and the BEM for the fluid. The solutions of SFEM are often found to be much more accurate than those of the FEM model. Based on its attractive features, it was decided in the present work to extend SFEM further for use in structural-acoustic analysis by coupling it with BEM, the present SFEM/BEM is implemented to predict the vehicle structure-acoustic frequency response analysis, and two numerical experiments results show that the present method can provide more accurate results compared with the standard FEM/BEM using the same mesh. It indicates that the present SFEM/BEM can be widely applied to solving many engineering noise, vibration and harshness (NVH) problems with more accurate solutions.

17

Comparative analysis of three ionospheric broadcast models for global navigation satellite systems

Li S., Li L., Wang S., Peng J., Xu Y., Zhao Y.

Acta Geophysica

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2017

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Vol. 65, no. 2

395--410

EN

An ionospheric model and corresponding coefficients broadcasted via GNSS navigation message are generally used to estimate the time delay for single-frequency GNSS users. In this article, the capabilities of three ionospheric models, namely, Klobuchar model, NeQuick Galileo version (NeQuick G), and Neustrelitz TEC broadcast model (NTCM-BC), were assessed. The models were examined in two aspects: total electron content (TEC) prediction and ionospheric delay correction effects in single-point positioning. Results show that both NeQuick G and NTCM-BC models outperformed Klobuchar model for predicting global TEC values during all the test days. Compared with Slant TEC (STEC) along the receiver-to-satellite ray path derived from IGS global ionosphere map (GIMs), STEC from NeQuick G and NTCM-BC models tend to have less bias than those from Klobuchar model in most situations. The point positioning results were improved by applying ionospheric broadcast models especially at the mid- and low-latitude stations.

18

In-situ coal seam and overburden permeability characterization combining downhole flow meter and temperature logs

Busse J., Scheuermann A., Bringemeier D., Hossack A., Li L.

Contemporary Trends in Geoscience

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2016

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Vol. 5, iss. 1

1--17

EN

The planning and design of any coal mine development requires among others a thorough investigation of the geological, geotechnical and hydrogeological subsurface conditions. As part of a coal mine exploration program we conducted heat pulse vertical flow meter testing. The flow data were combined with absolute and differential temperature logging data to gain information about the hydraulic characteristics of two different coal seams and their over- and interburden. For the strata that were localised based on geophysical logging data including density, gamma ray and resistivity hydraulic properties were quantified. We demonstrate that the temperature log response complements the flow meter log response. A coupling of both methods is therefore recommended to get an insight into the hydraulic conditions in a coal seam and its overburden.

19

Variability of Ionospheric TEC and the Performance of the IRI-2012 Model at the BJFS Station, China

Li S., Li L., Peng J.

Acta Geophysica

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2016

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Vol. 64, no. 5

1970--1987

EN

We studied variation characteristics of ionospheric total electron contents (TEC) and performance of the International Reference Ionosphere (IRI)-2012 model in predicting TEC at the BJFS (Beijing Fangshan station), China. Diurnal and seasonal variations were analyzed with TEC data derived from dual-frequency global positioning system (GPS) observations along with the solar activity dependence of TEC at the BJFS station. Data interpolated with information from IGS Global Ionosphere Maps (GIMs) were also used in the analysis. Results showed that the IRI-2012 model can reflect the climatic characteristics and solar activity dependence of ionospheric TEC. By using time series decomposition method, ionospheric daily averaged TEC values were divided into the periodic components, geomagnetic activity component, solar activity component and secular trend. Solar activity component and periodic components are supposed to be the main reasons which account for the difference between the GIMs TEC and the TEC from the IRI-2012 model.

20

Carbon-based acid catalyst from waste seed shells: preparation and characterization

Wang L. H., Liu H., Li L.

Polish Journal of Chemical Technology

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2015

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Vol. 17, nr 4

37--41

EN

A carbon-based solid acid catalyst was prepared by the sulfonation of carbonized seed shells of Jatropha curcas (J. curcas L.). The structure of amorphous carbon consisting of polycyclic aromatic carbon sheets attached a high density of acidic SO3H groups (2.0 mmol · g−1) was identified with scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The performance of the solid acid catalyst was evaluated for biodiesel production in the esterification of oleic acid with methanol. 95.7% yield of biodiesel was obtained after 2 h reaction and the conversions with reused catalyst varied in the range of 95.7% to 95.1%, showing better activity and stability than commercial catalyst amberlyst-46. It was also observed that the prepared catalyst showed enhanced activity in the transesterification of triolein with methanol when compared with other solid acid catalysts. A synergistic effect results from the high density of SO3H groups and the good access of reactants to the acidic sites can be used to explain the excellent catalytic activity, as well as the strong affinity between the hydrophilic reactants and the neutral OH groups bonded to the polycyclic aromatic carbon rings.