多面层沥青混凝土路面芯样密度试验方法浅析

分析了多面层沥青混凝土路面芯样密度试验方法

Microstructures,mechanical and oxidation behaviors of C/C composites modified by NiAl alloy

Carbon/carbon composites modified by NiAl alloy were prepared using vacuum reactive melt infiltration methods with NiAl and titanium mixed powders as raw materials. The microstructures were investigated by scanning electron microscopy. The fracture behavior, infiltration and oxidation mechanism were further discussed. The results indicated that NiAl alloy exhibited good wettability on the C/C preform because a TiC reaction layer formed at the interface. Multi-layer（PyC/TiC/NiAl＋TiC） coating evenly and compactly distributed on the surface of the carbon fiber in tubular form. The penetration depth of molten NiAl alloys depended on the reaction between the PyC and titanium. The impact fracture was inclined to along the interface between the NiAl permeability layer and C/C matrix. Al_2TiO_5 and TiO_2 formed on the surface, while the interior multi-layer tubular structure partially remained after oxidation at 1773 K for 30 min.

Effects of surface roughness of substrate on properties of Ti/TiN/Zr/ZrN multilayer coatings

Ti/TiN/Zr/ZrN multilayer coatings were deposited on Cr_17Ni_2 steel substrates with different surface roughnesses by vacuum cathodic arc deposition method. Microstructure, micro-hardness, adhesion strength and cross-sectional morphology of the obtained multilayer coatings were investigated. The results show that the Vickers hardness of Ti/TiN/Zr/ZrN multilayer coating, with a film thickness of 11.37 μm, is 29.36 GPa. The erosion and salt spray resistance performance of Cr_17Ni_2 steel substrates can be evidently improved by Ti/TiN/Zr/ZrN multilayer coating. The surface roughness of Cr_17Ni_2 steel substrates plays an important role in determining the mechanical and erosion performances of Ti/TiN/Zr/ZrN multilayer coatings. Overall, a low value of the surface roughness of substrates corresponds to an improved performance of erosion and salt spray resistance of multilayer coatings. The optimized performance of Ti/TiN/Zr/ZrN multilayer coatings can be achieved provided that the surface roughness of Cr_17Ni_2 steel substrates is lower than 0.4μm.

INTERFACIAL BONDING IN AS DEPOSITED AND ANNEALED Co/C SOFT X RAY MULTILAYER MIRRORS

Interfacial bonding in as deposited and annealed Co/C soft X ray multilayer structures is investigated by X ray photo electron spectroscopy (XPS).It is found that there is interdiffusion between cobalt and carbon in the as deposited Co/C multilayers,and this is confirmed by structure characterization using low angle X ray diffraction (LAXD).The calculation of the chemical shifts in Co C system based on Miedemas macroscopic atom model suggests that it is impossible to detect the chemical shift experimentally in the Co C compound,which is consistent with the XPS results.The presence of metallic carbide bonding is evidenced through the nature of the carbon bonding in survey taken at Co C and C Co interfaces of annealed samples.Our results also indicate that XPS is a direct method to probe the chemical bonding at the interfaces.

Fabricating a Micro Electromagnetic Actuator with High Energy Density

This paper introduces a new technology to fabricate a micro electromagnetic actuator with high energy density without an enclosed magnetic circuit. This technology includes fabricating multi-turns planar micro coils and fabricating the thick magnetic （NiFe） core on the silicon wafer. The multi-turns planar micro coils are fabricated by the electroplating method from the surface along the line and by dynamically controlling the current density of the copper electrolytes. In order to fabricate thick NiFe plating,the adhesion properties between the NiFe plating and the silicon substrates are improved by changing the surface roughness of the silicon substrates and increasing the thickness of the seed layer. Furthermore,the micro electromagnetic actuator is tested and the energy density of the actuator is evaluated by force testing. The experiments show that the microactuator is efficient in producing high magnetic energy density and high magnetic force.

Mechanical properties and friction-wear characteristics of VN/Ag multilayer coatings with heterogeneous and transition interfaces

The heterogeneous multilayer interface of VN/Ag coatings and transition multilayer interface of VN/Ag coatings were prepared on Inconel 781 and Si(100),and the microstructures,mechanical and tribological properties were investigated from 25 to 700℃.The results showed that the surface roughness and average grain size of VN/Ag coatings with transition multilayer interface are obviously larger than those of VN/Ag coatings with heterogeneous multilayer interface.The coatings with transition multilayer interface have higher adhesion force and hardness than the coatings with heterogeneous multilayer interface,and both coatings can effectively restrict the initiation and propagation of microcracks.Both coatings have excellent self-adaptive lubricating properties with a decrease of friction coefficient as the temperature increases,but their wear rates reveal a drastic increase.The phase composition of the worn area of both coatings was investigated,which indicates that a smooth Ag,Magnéli phase(V2O5)and bimetallic oxides(Ag3VO4 and AgVO3)can be responsible to the excellent lubricity of both coatings.To sum up,the coatings with transition multilayer interface have excellent adaptive lubricating properties and can properly control the diffusion rate and release rate of the lubricating phase,indicating that they have great potential in solving the problem of friction and wear of mechanical parts.

A new electromagnetic functional material composed of metallic hollow micro-spheres

This paper presents a new electromagnetic functional material developed byelectron-less nickel deposition technique, with a single hollow micro-sphere as the core templateand a thin nickel layer as the shell. The micrograph taken by a scanning electron microscope showsthe microstructures of the materials in detail. Scattering parameters of the waveguide sample holderfilled with the materials have been obtained over X band. The electromagnetic parameters computedfrom the measured S parameters show that the material with metallic hollow spheres has as highrelative permeability μ'_r as 19.0 with about 0.6 magnetic loss tangent over the whole bandwidth.Compared to the material with non-metallic spheres, the permeability μ'_r and the magnetic losstangent μ'_r increase greatly, while the permittivity remains lower than 1.8.

Composition and hardness of mullite coatings formed with direct current power supply on LY12 aluminum alloy surface

The surface modification of aluminum and its alloys using plasma technology is increasingly being investigated, Thick ceramic coatings with high hardness on aluminum alloys can be prepared successfully using a micro-plasma oxidation （MPO） technique. In this work, the composition, microstructure and elemental distribution of ceramic coatings formed by MPO on LY 12 almnlnum alloy and its hardness are investigated using XRD, EPMA and microhardness instruments. The results show that the ceramic coatings consist of mullite,γ-Al2O3 and a lot of amorphous matter. The content of silicon in the coatings increases from interface to the coatings, however, the content of aluminum decreases along this direction. The maximum hardness of ceramic coatings is up to 9.2 GPa.

Scattering of Oblique Surface Waves by the Edge of Small Deformation on a Porous Ocean Bed

The scattering of oblique incident surface waves by the edge of a small cylindrical deformation on a porous bed in an ocean of finite depth, is investigated here within the framework of linearized water wave theory. Using perturbation analysis, the corresponding problem governed by modified Helmholtz equation is reduced to a boundary value problem for the first-order correction of the potential function. The first-order potential and, hence, the reflection and transmission coefficients are obtained by a method based on Green＇s integral theorem with the introduction of appropriate Green＇s function. Consideration of a patch of sinusoidal ripples shows that when the quotient of twice the component of the incident field wave number along x-direction and the ripple wave number approaches one, the theory predicts a resonant interaction between the bed and the free-surface, and the reflection coefficient becomes a multiple of the number of ripples. Again, for small angles of incidence, the reflected energy is more as compared to the other angles of incidence. It is also observed that the reflected energy is somewhat sensitive to the changes in the porosity of the ocean bed. From the derived results, the solutions for problems with impermeable ocean bed can be obtained as particular cases.

Determination of the Real Surface Area of Palladium Electrode

Four methods, including voltammetric measurement of double layer capacitance, surface oxides reduction, under potential deposition of Cu and carbon monoxide （CO） stripping have been applied to evaluate the real surface area of a polycrystalline Pd （pc-Pd） electrode. The results reveal that the second and third methods lead to consistent results with deviations below 5%. And from the determined double layer capacitance and CO stripping charge, it is deduced that the double layer capacity unit area is 23.1±0.4μF/cm2 and the saturated CO adlayer should be ca. 0.66 ML in order to ensure that the real surface area as determined is consistent with the other two techniques. The applicability as well as the attentions when applying these techniques for the determination of the real surface area of pc-Pd electrodes have been discussed.

Computer aided modeling and pore distribution of bionic porous bone structure

Artificial bone with porous structure is crucial for tissue scaffold and clinic implants.Scaffold provides structure support for cells and guides tissues regeneration for final tissue structure.A computational aided process of porous bone modeling was developed which described the design and fabrication of tissue scaffolds by considering intricate architecture,porosity and pore size.To simulate intricate bone structure,different constructive units were presented.In modeling process,bone contour was gotten from computed tomography(CT)images and was divided into two levels.Each level was represented by relatively reconstructive process.Pore size distribution was controlled by using mesh generation.The whole hexahedral mesh was reduced by unit structure,when a 3D mesh with various hexahedral elements was provided.The simulation results show that constructive structure of porous scaffold can meet the needs of clinic implants in accurate and controlled way.

ENVIRONMENTAL EVOLUTION OF ORDOS DESERT IN CHINA SINCE 1.1MA B. P. AS INDICATED BY YULIN STRATIGRAPHICAL SECTION AND ITS GRAIN-SIZE ANALYSIS RESULTS

Yulin section is a typical sedimentary record for reflecting the environmental evolution of Ordos Desert, China in the past 1.1Ma. By analyzing its sequence and grain-size composition some views have been put forward in this paper as follows. The layers of sand, loess and palaeosol in Yulin section were respectively formed by wind and the pedogenesis on parent material of the sand and loess. Since 1.1Ma B. P., Ordos Desert has alternately experienced 11 stages of shifting dunes under extreme cold-dry climatic environment, 7 stages of fixed and semi-fixed dunes and 8 stages of dust (loess) under cold-dry climatic condition; and the pedogenesis environment under 15 times of warm-humid climate and 3 times of temperate-humid climate (brownish-drab soils and black soils formed respectively). The aeolian sand had already existed in Ordos Desert at latest by 1.1Ma B. P., and from that time on it has undergone a series of alternative processes of shifting sands, fixed and semi-fixed dunes, loess and soils. Ordos Desert has been situated in the transitional belt of the Mongolian High Pressure and margin of the southeast summer monsoon since 1.1Ma B. P., and influenced repeatedly by migration of the lithofacies belts of shifting sands, fixed and semi-fixed dunes, loess and soils, which have been caused by the climatic fluctuations of glacial and interglacial periods.

George Orwell＇s Non-linear Narrative in The Road To Wigan Pier

Orwell＇s text The Road to Wigan Pier, henceforth referred to as RWP, is problematic due to the ambiguity of its status as a literary genre. The text is subversive on many levels, namely on the level of form. In order to show some aspects of the author＇s challenge of the conventional norms and methods of literary writing, a comparison between the writer＇s original diary of the journey to the industrial North of England, the main site of the coal mines, and the present book could be of great import. This reveals the author＇s genuine intellectual ability to manipulate and rearrange the events and scenes of the story on the discourse level. The author＇s manipulation and rearrangement of the story （the journey）, events and scenes, clearly reveals his potential literary creativity and imagination. Orwell has deployed many strategies to fulfil this purpose. Each strategy is actually a contribution to the author＇s overall argument and at the same time it constitutes a further aspect of subversion. The first aspect of subversion lies on the level of form itself. The form of the book is effectively very challenging. Contrary to the conventional view of the fictional novel, the study of Orwell＇s text based on Grrard Genette＇s model reveals his challenge of the basic novelistic parameters. The novelistic ingredients such as setting, characterisation, and plot development have been treated in a subverting way. Though not totally discarded, they have been manipulated for the purpose of the author＇s general argument, which is Socialism. For instance, characters in the novel are treated as types, that is, representatives of their class. Besides, the order of scenes and events has been rearranged for the purpose of foregrounding representative scenes like the description of the Brookers＇ lodging-house. The author＇s treatment of the material of the text is primarily based on his personal experience as an outside observer during his journey to the North. Therefore, the exploration of the novel from a structuralist perspective based on Genette＇s model does not merely aim at the pure application of some literary and critical approaches to Orwell＇s text. This may be misleading since the investigation may fall in superficiality and simplicity. But the strategy deployed is actually a further contribution to the author＇s general argument and a manifestation of the novel＇s status as a creative and subversive text.

Multiscale Characterization of Automotive Surface Coating Formation for Sustainable Manufacturing

Automotive surface coating manufacturing is one of the most sophisticated and expensive steps in automotive assembly. This step involves generating multiple thin layers of polymeric coatings on the vehicle surface through paint spray and curing in a multistage, dynamically changing environment. Traditionally, the quality control is solely post-process inspection based, and process operational adjustment is only experience based, thus the manufacturing may not be （highly） sustainable. In this article, a multiscale system modeling and analysis methodology is introduced for achieving a sustainable application of polymeric materials through paint spray and film curing in automotive surface coating manufacturing. By this methodology, the correlations among paint material, application processes and coating performance can be identified. The model-based analysis allows a comprehensive and deep study of the dynamic behaviors of the material, process, and product in a wide spectrum of length and time. Case studies illustrate the efficacy of the methodology for sustainable manufacturing.

Simulation of thermal field induced by concave spherical transducer in multi-layer media

High intensity focused ultrasound(HIFU)therapy is an effective method in clinical treatment of tumors,in order to explore the bio-heat conduction mechanism of in multi-layer media by concave spherical transducer,temperature field induced by this kind of transducer in multi-layer media will be simulated through solving Pennes equation with finite difference method,and the influence of initial sound pressure,absorption coefficient,and thickness of different layers of biological tissue as well as thermal conductivity parameter on sound focus and temperature distribution will be analyzed,respectively.The results show that the temperature in focus area increases faster while the initial sound pressure and thermal conductivity increase.The absorption coefficient is smaller,the ultrasound intensity in the focus area is bigger,and the size of the focus area is increasing.When the thicknesses of different layers of tissue change,the focus position changes slightly,but the sound intensity of the focus area will change obviously.The temperature in focus area will rise quickly before reaching a threshold,and then the temperature will keep in the threshold range.

The upper-ocean response to typhoons as measured at a moored acoustic Doppler current profiler

A moored acoustic Doppler current profiler(ADCP) data,satellite-derived sea surface wind data,and the chlorophyll-a concentration were used to examine the influence of typhoon events on the upper ocean in the central Luzon Strait. The data were collected between August 27 and October 6,2011. Large changes in ocean dynamics and marine life were recorded in the upper layers over the short term during the transit of each of the three violent typhoons that passed over the region during the study period. The geostrophic flow during the period of ADCP monitoring was comparable to the Ekman flow,recently shown to be prominent in the upper layer. Based on the influence of the three typhoon events that swept the Luzon Strait or traversed Luzon Island on their way to the South China Sea,we postulated a typhoon-induced upwelling around the ADCP and found that upward isothermal displacements reached 11.8–39.0 m,which was confirmed by the sea-level anomaly data recorded at the same time. This variability in the upper ocean may play an important role in biological activity,especially in offshore deep-sea regions.

通信枢纽楼能耗运行分析研究

如何在业务量不断增加,电源容量无法扩容的情况下,更好地解决供电能力紧张、机房装机位不足、机房散热等问题,是本论文的研究意义所在。本文通过对S省通信枢纽楼能耗运行分析,给出以上难点的合理化建议和建设指导原则。

STUDY OF SOURCES OF SCORE VARIABILITY IN PERFORMANCE ASSESSMENT USING MFRM:A CASE OF SPEAKING TEST IN PETS BAND3

As direct measure of learners' communicative language ability, performance assessment (typically writing and speaking assessment) claims construct validity and a strong power for predictive utility of test scores. However, it is also of common concern that the subjectivity of rating process and the potential unfairness for test takers who encounter different writing prompts and speaking tasks would constitute threats to reliability and validity of test scores, especially in those large-scale and high-stakes tests. Therefore, appropriate means for quality control of subjective scoring should be held essential in test administration and validation. Based upon raw scores from one administration of speaking test in PETS Band3 held in Hangzhou, the present study investigates and models possible sources of score variability within the framework of Many-Facet Rasch Model (MFRM). MFRM conceptualizes the possibility of a examinee being awarded a certain score as a function of several facets — examinee ability, rater severity, domain difficulty and step difficulty between the adjacent score categories and provides estimates of the extent to which the examinee's test score is influenced by those facets. Model construction and data analysis was carried out in FACETS Version 3.58, computer program for conducting MFRM analysis. The results demonstrate statistically significant differences within each facet. Despite the generally acceptable rater consistency across examinees and rating domains, fit statistics indicate some unexpected rating patterns in certain raters such as inconsistency and central tendency, to be avoided through future rater training. Fair scores for each examinee are also provided, minimizing the variability due to facets other than examinees' ability. MFRM manifests itself as effective in detecting whether each test method facet functions as intended in performance assessment and providing useful feedback for quality control of subjective scoring.

Necessary and sufficient condition for the comparison theorem of multidimensional anticipated backward stochastic differential equations

Anticipated backward stochastic differential equations, studied the first time in 2007, are equations of the following type:{-dY t = f(t1, Y t1 , Z t1 , Y t+δ(t) , Z t+ζ(t) )dt Z t dB t1 , t ∈ [0, T ], Y t = ξ t1 , t ∈ [T, T + K], Z t = η t1 , t ∈ [T, T + K].In this paper, we give a necessary and sufficient condition under which the comparison theorem holds for multidimensional anticipated backward stochastic differential equations with generators independent of the anticipated term of Z.

Energy flux characteristics of seismic waves at the interface between soil layers with different saturations

Based on the multiphase poroelasticity theory describing the propagation of waves in the unsaturated fluid-saturated porous medium,the reflection and transmission coefficients of the seismic waves at the interface between soil layers with different saturations are obtained.Our unsaturated model consists of a deformable skeleton in which two compressible and viscous fluids(i.e.,water and gas)flow in the interstices.Three compressional waves(i.e.,P1,P2,and P3 waves)and one shear(i.e.,S wave)wave exist in the unsaturated soils.The expressions for the energy ratios of the various reflected and transmitted waves at the interface during the transmission and reflection processes are presented in explicit forms accordingly.At last,numerical computations are performed and the results obtained are respectively depicted graphically.The variation of the energy ratios with the incident angle,wave frequency and saturation degrees of the upper and lower soil layers is illustrated in detail.The calculation results show that the allocation of incident seismic waves at the interface is influenced not only by the angle and frequency of the incident seismic waves,but also by the saturations of the upper and lower soil layers.It is also verified that,at the interface,the sum of energy ratios of the reflected and transmitted waves is approximately equal to unity as was expected.This study is of importance to several fields such as geotechnical engineering,seismology,and geophysics.