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We present a novel simple microstructure model of financial returns that combines (i) the well-known ARFIMA process applied to tick-by-tick returns, (ii) the bid-ask bounce effect, (iii) the fat tail structure of the distribution of returns and (iv) the non-Poissonian statistics of inter-trade intervals. This model allows us to explain both qualitatively and quantitatively important stylized facts observed in the statistics of both microstructure and macrostructure returns, including the short-ranged correlation of returns, the long-ranged correlations of absolute returns, the microstructure noise and Epps effects. According to the microstructure noise effect, volatility is a decreasing function of the time-scale used to estimate it. The Epps effect states that cross correlations between asset returns are increasing functions of the time-scale at which the returns are estimated. The microstructure noise is explained as the result of the negative return correlations inherent in the definition of the bid-ask bounce component (ii). In the presence of a genuine correlation between the returns of two assets, the Epps effect is due to an average statistical overlap of the momentum of the returns of the two assets defined over a finite time-scale in the presence of the long memory process (i).

In this paper, the micro-structure and laser damage threshold of nano-ZrO₂ thin films were investigated. High-purity nano-ZrO₂ particles as the coating materials of samples were prepared by the electron beams evaporation. The micro-structure and crystallitic size of samples were analyzed by X-ray diffraction, a laser by 1064nm, 10ns, 3Hz Nd:YAG laser damage test each for nano-ZrO₂ films. The results showed that oxygen partial pressure has an important influence on the micro-structure of nano-ZrO₂ films, also found that the crystallitic size and different micro-structure influenced the laser damage threshold. The obtained results showed that laser damage threshold of polycrystalline structure is obviously higher than that of amorphous structure.

Aluminum alloy 5083 was joined with Sn–$x$Zn ($x=0$, 5, 9, 30 and 60 wt.%) filler metal by ultrasonic soldering at 400${}^{\circ }$C. The joint microstructure consisted of $\beta$-Sn and $\alpha$-Al solid–solution phases when using pure Sn solder. Zn-rich phases were observed in the joints with Sn–Zn filler metal. The Zn-rich phases grew thicker and larger with the increase in Zn content in the filler metal. The joints soldered with Sn–30Zn filler metal reached a maximum shear strength of 70 MPa. Joint cracking occurred at the interface of pure Sn and Sn–9Zn solders as indicated by SEM observation of the fracture surfaces. The locations of the fracture surface moved from the interface to the seam when using the Sn–30Zn or Sn–60Zn filler metal. The coarse Zn-rich phases were also observed on the fracture surface using Sn–60Sn solder, which results in a shear strength reduction of the joints.

We report the results of annealing effects on structural and superconducting properties (T_c and J_c) of various MgB₂/Fe wires that are produced by different conditions. Good quality superconducting MgB₂/Fe wires are fabricated by the powder-in-tube (PIT) technique at ambient pressure. XRD data confirms that they are hexagonalMgB₂ structure. All the annealed samples show higher T_c values in the range of 34.6–38.4 K with J_c higher than the as-rolled wire. The annealed samples show significant change in the J_c values as well as in micro-structural features due to variable sintering temperature. On annealing at 1050°C for 10 min, we obtain the best quality sample with a J_c of 37.2 kA/cm² at 33.1 K and self-field with a maximum T_c of 38.4 K. Among the samples annealed at 1050°C for 5–20 min, the 20 min sample shows lower J_c. Longer annealing time (at 1050°C) reduced J_c, indicating a possible interfacial reaction between the Fe sheath and the MgB₂ core.

Calcium carbonate whisker (CW) can work as a cost-effective and environment friendly micro-fiber in reinforcing cementitious composites. Influence of high temperature on micro-structure of CW reinforced cement paste by nanoindentation and mercury intrusion porosimetry test is studied in this research. Up to 500${}^{\circ }$C, the indentation depth, elasticity modulus, indentation hardness and interfacial transition zone (ITZ) width of CW reinforced cement paste are near or even better than that at room temperature, due to the coupling effect of CW transformation from aragonite to calcite and internal autoclaving. However, when the temperature is higher than 700${}^{\circ }$C, nano-mechanical properties of CW reinforced cement paste degenerated significantly, due to the decomposition of CW and hydration products. Similarly, with the increase of temperature up to 400${}^{\circ }$C, the porosity and pore size increase little or even decrease, while the fractal dimension of pore volume increases. With the introduction of CW, the pore parameters and fractal dimension are decreased up to 400${}^{\circ }$C, due to the filler effect of CW. When the temperature is higher than 700${}^{\circ }$C, the pore diameter and fractal dimension of CW reinforced cement paste are significant higher than that of pure cement paste, due to the decomposition of CW and hydration products. In CW reinforced cement paste, the fractal dimension was increased with the increased temperature and porosity in this research. There are negative correlations between the pore volume fractal dimensions and the strengths of CW reinforced cement paste. Fractal dimension is a useful tool to evaluate the change of pore structure at high temperature.

Cathodic arc evaporation (CAE) is a widely-used technique for generating highly ionized plasma from which hard and wear resistant physical vapor deposition (PVD) coatings can be deposited. A major drawback of this technique is the emission of micrometer-sized droplets of cathode material from the arc spot, which are commonly referred to as "macroparticles." In present study, titanium nitride (TiN) coatings on high-speed steel (HSS) coupons were produced with a cathodic arc evaporation technique. We studied and discussed the effect of various nitrogen gas flow rates on microstructural and mechanical properties of TiN-coated HSS coupons. The coating properties investigated in this work included the surface morphology, thickness of deposited coating, adhesion between the coating and substrate, coating composition, coating crystallography, hardness and surface characterization using a field emission scanning electron microscope (FE-SEM) with energy dispersive X-ray (EDX), X-ray diffraction (XRD) with glazing incidence angle (GIA) technique, scratch tester, hardness testing machine, surface roughness tester, and atomic force microscope (AFM). An increase in the nitrogen gas flow rate showed decrease in the formation of macro-droplets in CAE PVD technique. During XRD-GIA studies, it was observed that by increasing the nitrogen gas flow rate, the main peak [1,1,1] shifted toward the lower angular position. Surface roughness decreased with an increase in nitrogen gas flow rate but was higher than the uncoated polished sample. Microhardness of TiN-coated HSS coupons showed more than two times increase in hardness than the uncoated one. Scratch tester results showed good adhesion between the coating material and substrate. Considerable improvement in the properties of TiN-deposited thin films was achieved by the strict control of all operational steps.

Today there is major interest within the biomedical community in developing accurate non-invasive means for evaluation of bone micro-structure and bone quality. Recent improvements in 3D imaging technology, among them development of micro-CT and micro-MRI scanners, allow in-vivo 3D high-resolution scanning and reconstruction of large specimens or even whole bone models. Thus, the tendency today is to evaluate bone features using 3D assessment techniques rather than traditional 2D methods. For this purpose high quality meshing methods are required. However, the 3D meshes produced from current commercial systems usually are of low quality with respect to analysis and rapid prototyping. 3D model reconstruction of bone is difficult due to the complexity of bone micro-structure. The small bone features lead to a great deal of neighborhood ambiguity near each vertex.

The relatively new Neural Network method for mesh reconstruction has the potential to create or remesh 3D models accurately and quickly. A Neural Network (NN), which resembles an artificial intelligence (AI) algorithm, is a set of interconnected neurons, where each neuron is capable of making an autonomous arithmetic calculation. Moreover, each neuron is affected by its surrounding neurons through the structure of the network. This paper proposes an extension of the Growing Neural Gas Neural Network (GNG NN) technique for remeshing a triangular manifold mesh that represents bone micro structure. This method has the advantage of reconstructing the surface of an n-genus freeform object without a priori knowledge regarding the original object, its topology, or its shape.

A model to describe the micro-structure of macromolecular microsphere composite (MMC) hydrogel is proposed in the framework of self-consistent mean field theory (SCMFT),¹ which is usually used to investigate copolymer. Based on the SCMFT approximation, a system of equations associated with the complex topology of MMC hydrogel is derived and solved by a new kind of relaxation algorithm successfully. From the numerical simulation of the model, we find that the two model parameters play important roles in describing the micro-structure of MMC hydrogel, the interactions between two species (polymer chains and MMS spheres) and the volume fraction of MMS spheres. The role of other model parameters on the structure of the MMC hydrogel is also discussed. The numerical results are consistent with the observation from the chemical experiments. Moreover, we also show some new micro-structures obtained by using the SCMFT model, but discovered in chemical experiments.

In this paper, a nanocrystalline surface has been successfully induced on NO.45 steel plates by fast multiple rotation rolling. XRD and TEM, micro-hardness measurement has been carried out to investigate the change in micro-structure and physical properties. It also covers research done on the effect of treatment time on the grain refinement. The results shows that 60min duration has a relatively better refining effect: size of surface grain reduces to 37.4nm, smaller than that 47.6nm of samples treated for 30min. The effected thickness is about 90μm, and the topmost micro-hardness can be 458HV, improved by approximately 91% than as-receive sample. Sample treated for 30min has a 55μm thickness affected layer; the highest hardness value is 395HV.