Wyniki wyszukiwania - BazTech

1

Enhanced magnetoelastic performance in Pr/Mn-doped Laves phase (Tb,Ho)Fe2 compounds

Wang M. K., Liu J. J., Lv X. J., Ding Q. L., Li F., Pan Z. B., Xia W. X., Du J.

Materials Science Poland

|

2020

|

Vol. 38, No. 4

707--714

EN

Magnetostrictive TbxHo0.8−xPr0.2Fe1.8Mn0.1 (0 ⩽ x ⩽ 0.20) alloys are prepared by arc-melting and subsequent annealing. The dopant of Pr/Mn introduced into RFe2 compounds effectively stabilizes the forming of single C15 Laves phase at ambient pressure. The easy magnetization direction (EMD) varies when Tb content increases, which is accompanied by a crystalstructural transition. EMD lies along ‹1 0 0› axis for x ⩽ 0.05, rotating to ‹1 1 1› axis for x ⩽ 0.12, with a tetragonal symmetry changing to a rhombohedral one. Magnetocrystalline-anisotropy compensation is obtained with the optimized composition of x = 0.12, shifting to the Tb-poor side in comparison to Pr/Mn-free counterpart. An enhanced effect on magnetoelastic properties is achieved in Tb0.12Ho0.68Pr0.2Fe1.8Mn0.1, which simultaneously possesses a low anisotropy and high magnetostriction performance, i.e. λs ~ 420 ppm, λ111 ~ 970 ppm, and a large low-field λa ~ 390 ppm/2 kOe, being 30 % higher than that of Pr/Mn-free compound. Combining low-cost light rare earth Pr with the lower Tb content, Tb0.12Ho0.68Pr0.2Fe1.8Mn0.1may make it promising solution in magnetostrictive applications.

2

Identifying the degree of luminescence signal bleaching in fluvial sediments from the Inner Mongolian reaches of the Yellow River

Li F., Pan B., Lai Z., Gao H., Ou X.

Geochronometria

|

2018

|

Vol. 45, no. 1

82--96

EN

The partial bleaching of the luminescence signal prior to deposition results in age overestimation, and can be a problem in delineating fluvial evolution within an OSL chronological framework. The Inner Mongolian reaches of the Yellow River are characterised by a high sediment load and complex sources of sediments. To test the incomplete bleaching occurring in this type of environment, the residual doses and the luminescence signal characteristics of different particle size fractions from 14 modern fluvial sediment samples were investigated. Furthermore, 26 OSL ages derived from drilling cores were compared with 11 radiocarbon ages. Our results show that the residual equivalent doses principally range between 0.16 and 0.49 Gy for silt grains, and between 0.35 and 3.72 Gy for sand grains of modern samples. This suggests that medium-grained quartz has been well bleached prior to deposition, and is preferable to coarse-grained quartz when dating fluvial sediments in this region. The results also show that the De values of coarse-grained fractions display a stronger correlation with distance downstream. In addition, a comparison of OSL and radiocarbon ages from drilling cores establishes further confidence that any initial bleaching of these sediments was sufficient. As a result, we believe that the studied fluvial samples were well bleached prior to deposition.

3

Dual reference beam digital off-axis holography for exact suppression of zero-order term and twin image without spectrum loss

Wang M., Wang K., Zheng M., Li F., Wu J.

Optica Applicata

|

2017

|

Vol. 47, nr 3

435--443

EN

In this paper, we describe an effective approach to suppressing zero-order term and twin image by using pixel-by-pixel multiplication of double holograms in digital off-axis holography. This method records two holograms, respectively, by using the reference waves in different directions. It shows not only a simpler algorithm and easier implementation in experiment, but also exact and complete suppression of the zero-order term and twin image without any spectrum loss of the object in the image reconstruction, particularly when the image and the zero-order term are fairly close to each other. The experimental result approves of the theoretical prediction very well. This approach provides an effective solution to suppressing undesired noises in the digital off-axis holography.

4

Magnetoelastic properties of epoxy resin based TbxHo0.9−xNd0.1 (Fe0.8Co0.2)1.93 particulate composites

Zhang Z. R., Liu J. J., Song X. H., Li F., Zhu X. Y., Si P. Z.

Materials Science Poland

|

2017

|

Vol. 35, No. 1

81--86

EN

TbHo_0.9−xNd_0.1 (Fe_0.8Co_0.2)Sub>1.93 (0 ≤ x ≤ 0.40) particulate composites were prepared by embedding and aligning alloy particles in an epoxy matrix with and without a magnetic curing field. The magnetoelastic properties were investigated as functions of composition, particle volume fraction and macroscopic structure of the composite. The magnetic anisotropy compensation point was found to be around x = 0.25, where the easy magnetization direction (EMD) at room temperature was detected lying along ⟨ 1 1 1 ⟩ axis. The composite with ⟨ 1 1 1 ⟩ preferred orientation and pseudo-1-3 type structure was prepared under an applied magnetic field of 12 kOe. An enhanced magnetoelastic effect and large low-field magnetostriction λ_a, as high as 430 ppm at 3 kOe, were obtained for Tb_0.25Ho_0.65 Nd_0.1 (Fe_0.8Co_0.2)_1.93composite rod. The value of λ_a was of 72 % of its polycrystalline alloy (~595 ppm/3 kOe) although it only contained 30 vol.% of the alloy particles. This enhanced effect can be attributed to the larger λ₁₁₁ (as compared to λ₁₀₀), low magnetic anisotropy, easy magnetization direction (EMD) along the ⟨ 1 1 1 ⟩ axis and ⟨ 1 1 1 ⟩-textured orientation of the alloy particles as well as the chain-like structure of the composite. The good magnetoelastic properties of the composite, in spite of the fact that it contained only 30 vol.% of the alloy particles with light rare-earth Nd element in the insulating epoxy, would make it a potential material for magnetostriction application.

5

Potato waste treatment by microbial fuel cell. Evaluation based on electricity generation, organic matter removal and microbial structure

Du H., Li F., Huang K., Li W., Feng C.

Environment Protection Engineering

|

2017

|

Vol. 43, nr 1

5--18

EN

The performance of microbial fuel cell (MFC) in treating potato waste was evaluated using a two-chamber MFC supplied with potato liquid after mastication of market available fresh potato. Evaluation was conducted based on electricity generation, organic matter removal (CODCr, DOC and volatile fatty acids (VFAs)), and microbial structure on the anode and in the anodic solution of the reactor. Current density exhibited a trend that followed the concentration changes of organic matter in the solution, with its highest value being observed as 208 mA/m2. Effective removal of organic matter was also observed. By the end of the experiment, the removal for total COD reached about 84%. Bacterial structure analysis based on PCR, DGGE and sequencing indicated that more species were developed in the anodic solution than on the anode, with Proteobacteria, Firmicutes and Bacteroides being dominant. Geobacter, a well reported exoelectrogenic species, was found more predominant on the anode than in the anodic solution. The results thus indicated that simultaneous stabilization and electricity generation could be achieved when potato waste is treated in MFC.

6

Copper recovery from waste printed circuit boards and the correlation of Cu, Pb, Zn by ionic liquid

Li F., Chen M.

Environment Protection Engineering

|

2017

|

Vol. 43, nr 4

55--66

EN

Waste printed circuit boards (WPCBs) contain not only harmful materials but also many valuable resources, especially metals, which attracts more and more attention from the public. In this study, a sulfonic acid functionalized ionic liquid ([BSO₃HPy]OTf) was used to recycle copper from WPCBs. Zinc and lead, represented as typical heavy metals, were chosen to study the leaching behavior and their relation to copper. Five factors such as particle size, ionic liquid (IL) concentration, H₂O dose, solid to IL ratio and temperature were investigated in detail. The results showed that copper leaching rate was high, up to 99.77%, and zinc leaching rate reached the highest value of 74.88% under the optimum conditions. Lead cannot be leached effectively and the leaching rate was mostly low than 10%, which indirectly indicated that [BSO₃HPy]OTf has a good selectivity to lead. Besides, the interaction of copper, lead and zinc was characterized macroscopically by means of statistical methods. The Spearman correlation analysis showed that copper and zinc had a highly positive correlation. Lead had little relation to copper, which to some extent indicated that the effect of zinc on copper leaching behavior was bigger than that of lead.

7

Wear Process Analysis of the Polytetrafluoroethylene/Kevlar Twill Fabric Based on the Components’ Distribution Characteristics

Gu D., Fan B., Li F., Yang Y., Chen S.

Autex Research Journal

|

2017

|

Vol. 17, no. 4

295--302

EN

Polytetrafluoroethylene (PTFE)/Kevlar fabric or fabric composites with excellent tribological properties have been considered as important materials used in bearings and bushing, for years. The components’ (PTFE, Kevlar, and the gap between PTFE and Kevlar) distribution of the PTFE/Kevlar fabric is uneven due to the textile structure controlling the wear process and behavior. The components’ area ratio on the worn surface varying with the wear depth was analyzed not only by the wear experiment, but also by the theoretical calculations with our previous wear geometry model. The wear process and behavior of the PTFE/Kevlar twill fabric were investigated under dry sliding conditions against AISI 1045 steel by using a ring-on-plate tribometer. The morphologies of the worn surface were observed by the confocal laser scanning microscopy (CLSM). The wear process of the PTFE/Kevlar twill fabric was divided into five layers according to the distribution characteristics of Kevlar. It showed that the friction coefficients and wear rates changed with the wear depth, the order of the antiwear performance of the previous three layers was Layer III>Layer II>Layer I due to the area ratio variation of PTFE and Kevlar with the wear depth.

8

Analysis of the influence on expressway safety of ramps

Hu J. J., Li F., Han B., Yao J.

Archives of Transport

|

2017

|

Vol. 43, iss. 3

43--51

EN

As the very important parts of the expressway system, on and off ramps have a great effect on the operation effect of expressways. Once congestion occurs at on and off ramps, it will directly affect the safety of the expressway and vehicles. So this paper first analyzes the location design of on ramps, the length and the influences on the expressway running state of off ramp downstream traffic state, and establishes the expressway operation models based at on and off ramps. The expressway operation models include off ramp delay model, on ramp delay model, expressway delay model and side road delay model under the influence of the distance between on and off ramp and traffic volume. At the same time, the paper analyzes the connection between the traffic operation state and traffic safety, and establishes the expressway safety model based on congestion degree. Through simulation verification, the impact of on and off ramp on the security of the expressway is analyzed. In the simulation, safety rank division is simulated to verify and safety index of different safety ranks. Finally the paper concludes that the delay caused by traffic of the on and off ramps can decrease the safety of expressway.

9

Evaluation of geological conditions for coalbed methane occurrence based on 3D seismic information: a case study in Fowa region, Xinjing coal mine, China

Li J., Li F., Hu M., Zhang W., Pan D.

Acta Geophysica

|

2017

|

Vol. 65, no. 2

345--351

EN

The research on geological conditions of coalbed methane (CBM) occurrence is of great significance for predicting the high abundance CBM rich region and gas outburst risk area pre-warning. The No. 3 coal seam, in Yangquan coalfield of Qinshui basin, is the research target studied by 3D seismic exploration technique. The geological factors which affect CBM occurrence are interpreted based on the 3D seismic information. First, the geological structure (faults, folds, and collapse columns) is found out by the 3D seismic structural interpretation and the information of buried depth and thickness of the coal seam is calculated by the seismic horizons. Second, 3D elastic impedance (EI) and natural gamma attribute volumes are generated by prestack EI inversion and multi-attribute probabilistic neural network (PNN) inversion techniques which reflect the information of coal structure types and lithology of the roof and floor. Then, the information of metamorphic degree of seam and hydrogeology conditions can be obtained by the geological data. Consequently, geological conditions of CBM occurrence in No. 3 coal seam are evaluated which will provide scientific reference for high abundance CBM rich region prediction and gas outburst risk area pre-warning.

10

Effects of unstable elements with different hardness on lower limb loading

Li F., Mei Q., Gu Y.

Acta of Bioengineering and Biomechanics

|

2015

|

Vol. 17, no. 2

85--92

EN

Purpose: Osteoarthritis of the knee is one of the most common diseases. For this chronic disease, modified footwear structure can effectively prevent and relieve disease of the knee. The aim of this study was to explore the effects of shoe surface elastic modulus on external knee adduction moment and ground reaction force and foot loading characteristics. Methods: Sixteen healthy female volunteers were recruited, and each subject performed five walking trials under two shoes condition. The lower limb loading data was collected using force platform and in-sole pressure measurement system. Results: The results showed that the external knee adduction moment was decreased in all stance phase when wearing SS (unstable shoes with soft unstable elements), compared with HS (unstable shoes with hard unstable elements). The ground reaction force showed no obvious change under two shoes condition. Additionally, compared with HS, plantar pressure transferred from medial foot to lateral foot when wearing SS. Along with changes of contact areas, average pressure and impulse had also presented this tendency. Conclusions: These results can provide some scientific evidence and suggestions for footwear companies, and for the foot plantar medial injury disease has also certain applicability.

11

Computational simulation analysis for torus radius of edge contact in hip prostheses

Li F., Chen H, Mao K.

Acta of Bioengineering and Biomechanics

|

2015

|

Vol. 17, no. 3

67--73

EN

Stripe wear occurs when the components of hip prostheses move a sufficient distance laterally to contact the edge of the acetabular cup, causing abnormally high contact stresses. In this research, edge loading contact of prosthetic hip is analyzed in the most commonly used material pairs. The contact dimensions and maximal contact pressure are investigated in mutative normal edge loading with 3 different inclination angles (15°, 20°, 25°) and in alterable edge torus radius with edge loading of 2500 N and inclination of 20°. A computational case was conducted for a 14 mm radius alumina ceramic bearing with a radial clearance of 0.1 mm using a normal edge loading ranged from 0 N to 3000 N. Additionally, the Hertzian theory successfully captures principal curvature trends of the edge torus on the influence of maximal contact pressure and obtains the appropriate edge radius range for lower maximal contact pressure. This work elucidates the methods of applying classical contact theory to design the edge radius of hip bearings to better resist severe edge loading contact stresses and reduce the stripe wear.

12

Insensitive HMX (Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) Nanocrystals Fabricated by High-Yield, Low-Cost Mechanical Milling

Wang Y., Jiang W., Song X., Deng G., Li F.

Central European Journal of Energetic Materials

|

2013

|

Vol. 10, no. 2

277--287

EN

A mechanical approach had been adopted for fabricating HMX nanoparticles. This fabrication method avoided the recrystallization process and was different from the traditional methods employed to prepare nanoexplosives. In particular, the high yield and low cost increased the possibility of its industrial application. Specifcally, HMX particles, that had a mean size of 0.27 μm, were prepared by mechanical milling; a signifcant proportion of nano-HMX (<100 nm) were present and these were observed by TEM and SEM images. The thermal decomposition of HMX samples before and after pulverization was investigated by TG/DSC analysis. The results indicated that there was no obvious difference between the thermographs of raw and pulverized HMX. The HMX samples were investigated by friction, impact, and shock sensitivity tests. High safety was confrmed since pulverized HMX was far more insensitive than raw HMX; indeed the shock sensitivity of pulverized HMX was about 60 percent lower than that of raw HMX.

13

Characteristics of elastic wave propagation in thick beams - when guided waves prevail?

Peng H., Ye L., Meng G., Sun K., Li F.

Journal of Theoretical and Applied Mechanics

|

2011

|

Vol. 49 nr 3

807-823

EN

Characteristics of wave propagation in thick beams are analyzed using a three-dimensional (3-D) spectral element method (SEM) for the purpose of damage detection. Analysis of wave propagation in beams of different thickness under excitations with different central frequency reveals that when the thickness of the beam is comparable to the wavelength of the elastic wave, a local wave mode, besides quasi-symmetric and quasi-anti-symmetric modes, exist simultaneously in the beam. In particular, when the wavelength is more than two times the beam thickness, the local wave modes are suppressed and the wave modes in the beam can be regarded as traditional guided waves, i.e., Lamb waves. It is demonstrated that the central frequency of wave signals can be selected according to the dimensions of the beam to obtain simple wave modes like those in thin beams. The characteristics of wave propagation in an intact beam and beams with a lateral crack are analyzed and the results are also validated by experiments, where wave propagation signals in thick steel beams are activated and captured using PZT elements.

PL

Praca przedstawia problem detekcji uszkodzeń w belkach o znacznej grubości za pomocą trójwymiarowej metody elementów spektralnych (SEM) ze szczególnym uwzględnieniem charakterystyk propagacji fal w ośrodku. Analiza rozchodzenia się fal w belkach o różnej grubości poddanych wymuszeniom o różnej częstotliwości centralnej ujawniła, że gdy grubość belki jest porównywalna z długością fali sprężystej, to oprócz quasi-symetrycznych i quasi-antysymetrycznych postaci pojawia się lokalna postać własna fali. Gdy długość fali przekracza co najmniej dwukrotnie grubość belki, postacie lokalne zanikają i postacie fal mogą zostać uznane jako tradycyjne fale prowadzone, tj. fale Lamba. Pokazano, że centralna częstotliwość sygnałów falowych może zostać dobrana do konkretnych rozmiarów belki tak, aby otrzymać proste postacie własne fal przypominające kształt fal rozchodzących się w belkach cienkich. W pracy zbadano charakterystyki propagacji fal w belce nieuszkodzonej i belce z pęknięciem poprzecznym. Rezultaty tych badań zweryfikowano doświadczalnie poprzez generowanie i rejestrację sygnałów w grubych stalowych belkach aktuatorami i czujnikami piezoelektrycznymi.

14

Cryptanalysis of an Identity Based Signcryption without Random Oracles

Xiong H., Qin Z., Li F.

Fundamenta Informaticae

|

2011

|

Vol. 107, nr 1

105-109

EN

Signcryption is a cryptographic primitive that performs digital signature and public key encryption simultaneously, at lower computational costs and communication overhead than signing and encrypting separately. Recently, Yu et al. proposed an identity based signcryption scheme with a claimed proof of security. We show that their scheme is not secure even against a chosen-plaintext attack.

15

Nitrogen doped carbon nanotubes and curved lamellas produced via pyrolysis of melamine by direct current arc discharge

Zhao R. I., Ma Y., Zhang J., Li F., Liu W., Cui Q.

Materials Science Poland

|

2010

|

Vol. 28, No. 1

189--198

EN

Nitrogen doped carbon nanostructures, including nanotubes and barrel like curved lamellas, were fabricated via the pyrolysis of a solo precursor, melamine, in a direct current arc discharge. The samples were characterized by elemental analysis, using XRD, XPS, TEM and SEM in parallel. The nitrogen concentration, determined from the elemental analysis, was shown to be lower than 5%. Nitrogen-based functional groups such as pyridine like structures, the pyrrolic or pyridonic structures, N-amine like structures and substitutional nitrogen within the graphene layers, were observed to coexist in the turbostratic carbon matrix. XRD patterns showed characteristic features of turbostratic carbons. TEM analysis of morphologies showed that nanostructures such as tubes and conglomerations of barrel like curved lamellas were present. The formation of bundles of nanotubes was further confirmed by SEM studies. The inhomogeneity in the morphologies of the nanostructures was attributed to the differences in their growth mechanisms.

16

Research and development of Multi-Agent System based agile collaborative design system for machining centre

Li F., Chen N., Zhou L.

Journal of Achievements in Materials and Manufacturing Engineering

|

2008

|

Vol. 31, nr 2

518-525

EN

Purpose: Today we face a demands always quickly varied market. For the machine tools manufacturers, reducing the development cycle of a product to be modified is much meaningful, and meanwhile, they have to improve (at least keep) the new machines performance. Consequently, an assistant-software has a certain degree of intelligent ability will have more advantages to improve the design quality and short design cycle simultaneously. Design/methodology/approach: The development of machine tools is a typical work of a distributed cooperative process supported by CAX. MAS (Multi-Agent system) is now the mainstream of contemporary studies on distributed intelligent software system, and can provide a foundation for the establishment of such system. Findings: In this paper, a MAS-based agile collaborative development system for MC (Machining Center) was set up using JADE (Java Agent DEvelopment framework). The whole system was divided into several functional modules that can carry out its typical mission. By taking the intelligent collaborative design module as an example, the configuration of Agents society was expatiated particularly. This module can provide intellectualized conceptual design help for MC designers. Research limitations/implications: Whereas, the other modules of this system have not been established, so in order to make it more perfect, some interfaces are left for the next expansion of other modules. Practical implications: A development process supported by this system for a customer ordered MC is taken to execute the prototype case study. According to the customer order information, three feasible proposals that have the greatest similarity are presented by the intelligent reasoning of CADDesignerAgents. By performing the parametric design and intelligent optimization, 3D dynamic MC model which is the customer satisfied is proposed and shown. Originality/value: The platform supported with those intelligent abilities has shown that it is a powerful tool on the MC family design for shorten the development cycle and improve the design quality.

17

An Improved Certificateless Signature Scheme Secure in the Standard Model

Xiong H., Qin Z., Li F.

Fundamenta Informaticae

|

2008

|

Vol. 88, nr 1-2

193-206

EN

In ASIACCS 2007, Liu et al proposed a certificateless signature scheme which is provably secure in the standard model. However, as we will show in this paper, the proposed scheme is insecure against a malicious-but-passive KGC attack. This implies that the malicious-but-passive KGC, which generates system parameters based on the information of the target user, can forge valid signatures for that signer without being detected. Furthermore, we propose an improved scheme that remedies the weakness of Liu et al’s scheme. The improved scheme can be proven secure against malicious-but-passive KGC attack in the standard model.

18

Separation of fudosteine on an achiral C 18 column by HPLC with chiral ligand-exchange selectors as mobile phase additives

Ma J., Cao J., Ding M. J., Yuan L. H., Zhai M. J., Zhang J., Zhang Q., Li F., Zhou X. M.

Acta Chromatographica

|

2008

|

Vol. 20, no. 4

585-594

EN

A reversed-phase chiral liquid chromatographic method had been developed and validated for resolution of the enantiomers of racemic fudosteine. The effects on the separation of the amounts of anhydrous cupric sulfate and L -phenylalanine, the methanol content, mobile phase pH, and temperature were investigated. The method was validated for linearity, repeatability, intermediate precision, sample recovery, solution stability, and limits of detection (LOD). L -Phenylalanine and anhydrous cupric sulfate as chiral ligand-exchange complexes were used for separation, isomer identification, related substance investigation, and analysis of fudosteine enantiomers in fudosteine bulk drugs and fudosteine tablets.

19

Security Analysis of the Pomykała-Barabasz Scheme

Li F., Hu Y.

Fundamenta Informaticae

|

2007

|

Vol. 80, nr 4

453-459

EN

In 2006, Pomykala and Barabasz [Fundamenta Informaticae 69 (2006) 411–425] proposed an elliptic curve based threshold proxy signature scheme which requires shorter cryptographic keys.They claimed that their scheme satisfies the secrecy, the proxy protected, the unforgeability, the non-repudiation, and the known signers. However, in this paper, we show that their scheme cannot achieve the proxy protected, the unforgeability and the non-repudiation by demonstrating a conspiracy attack. In this attack, any t malicious proxy signers can collusively impersonate some other proxy signers to generate proxy signatures.

20

Synthesis and Crystal Structure of Five-Coordinated Triorganotin Complexes with 2,5-Dimercapto-4-phenyl-1,3,4-thiodiazole

Zhang R., Li F., Li K., Ma C.

Polish Journal of Chemistry

|

2004

|

Vol. 78 / nr 6

753-760

EN

Reactions between triorganotin chloride and 2,5-dimercapto-4-phenyl-1,3,4- thiodiazole gave complexes R3Sn(S3N2C8H5) (4: R = Ph; 5: R = PhCH2 and 6: R = n-Bu), respectively. All products were characterized by elemental analysis, IR, 1H NMR, 13C NMR, and two of them ((4) and (5)) have been determined by X-ray crystallography. Including the Sn-N interaction, the tin atoms of three complexes all have five-coordinated distorted trigonal bipyramidal geometry. All three complexes have antitumor activity in bioactivity measurements. Crystal data for complex (4): monoclinic, space group P2(1)/c, a = 9.696(2)A,b = 14.773(3) A, c = 17.466(4)A, _ = 92.599(3)_, and Z= 4. Crystal data for complex (5): triclinic, space group P-1, a = 9.744(6) A, b = 16.338(10) A, c =17.957(12) A, _ = 90.000(12)_, _ = 100.735(11)_, _ = 90.000(12)_ and Z = 4.