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Molecular dynamics (MD) simulation with the embedded-atom method (EAM)/alloy potential is used to investigate the property of the nanoscale hollow spherical Nickel (Ni) powder during the laser additive manufacturing (AM) process. The thermomechanical properties of the Ni nanopowder is also explored (1) at room temperature and (2) from room temperature to the melting temperature during laser AM of powder bed fusion. As a result, the optimum parameters for the laser AM process are proposed. The optimal coalescence temperature of the nanoscale hollow spherical Ni powder is in the range between 980 and 1421K, while the melting temperature is in the range between 1320 and 1470 K. The coalescence and melting temperatures are lower than the melting point of Ni (1728 K).

Anti-reflection based on the mimicking of moth eye subwavelength structures (SWSs) has several advantages over conventionally used multilayer thin film antireflective coatings like broad angular and spectral responses, polarization insensitivity and improved stability. In this study, we present the low cost fabrication of moth eye based SWSs on flexible polyethylene terephthalate (PET) substrates using roll-to-roll ultraviolet nanoimprint lithography. We have used a novel method to create a roller mold with embedded nanopores that can be used for easy replication of SWSs without demolding issues. Pure aluminum foil was wrapped around an acrylic cylinder (O = 90 mm) and a multistep anodizing and pore widening scheme was employed to create well-ordered and periodic anodized aluminum oxide (AAO) nanopores with different aspect ratios. Optical characterization of the antireflective PET film shows a transmittance over 92%, an increase of 3% as compared to bare PET, while reflectance can be reduced from 5.3 to 0.09% in the range of visible light. It was observed that higher aspect ratio SWSs is more effective in reducing reflections at higher incident angles. Consequently, we have demonstrated an economically feasible method for fabricating large area polymer films that can be used to reduce light reflections which impose severe limitations on the performance of many optoelectronic devices like solar cells, photodetectors and flat display panels.

The molecular dynamics simulation method is utilized to investigate the physical characteristics of nanoscale vanadium powder during 3D printing powder bed fusion laser sintering process. The radius of gyration, neck width, and root mean square of different powder size of nanoscale vanadium powder during 3D printing laser sintering process under different heating rate is analyzed and discussed. The neck width and internal lattice changes are also observed.It is observed that the temperature of solid state diffusion decrease with heating rate increasing, but the temperature of that increase with powder size decreasing. It is found that the coalescence temperature of nanoscale vanadium powder is range of between 1600K and 1950K, and the melting temperature of that is range of between 1850K and 1990K.

The mechanisms that employ symmetrical configurations can be found in the steering mechanisms, double open refrigerator, roof boxes, and double open windows, among others. They are useful for some special applications with kinematic symmetry. There have been studies about the linkage synthesis, especially in the research of planar closed chains, from as early as 1960s. However, no study has focused on the symmetry of planar linkages. Thus, the purpose of this paper is to present a methodology to synthesize the configurations of planar linkages. The systematic methodology can be divided into structure synthesis, configuration synthesis and results produced from three major processes. Finally, four suitable results of up to six-bar linkages can be obtained, for example. The four results include one four-bar linkage and three six-bar linkages.

Transparent conductive electrodes (TCEs) possessing a combination of high optical transmission and good electrical conductivity find applications in numerous optoelectronic devices. A low cost fabrication of a fine metal-mesh structure on rigid (glass) and flexible (polyethylene terephthalate – PET) substrates as a promising and feasible approach for fulfilling large size TCE requirements is proposed. A roll-to-sheet ultraviolet imprinting protocol to transfer microtrench structures using a flexible Polydimethylsiloxane stamp is utilised. The conductive silver ink is filled into the microtrench structures by controlling the processing parameters which include pressure, scraping angle and speed. The metal-mesh based glass and PET substrates show a transmission of about 90%, while the electrical resistance is as low as 6 Ω/□. Thus, this method can be utilised as an economically viable alternative to doped indium oxide in TCE applications.

Molecular dynamics (MD) simulations were performed to study the torsional characteristics of a graphene nanoribbon encapsulated in a single-walled carbon nanotube (GNR@SWCNT) with different chiralities at different temperatures. Based on the simulations, the relationship between the shear stress and the twist angle was obtained. The maximum shear stress increases with an increase in chirality. However, the corresponding twist angle decreases with increasing chirality. GNR@SWCNT withstands a smaller twist angle compared with a single SWCNT. In addition, the interaction force between the GNR and the SWCNT increases with increasing temperature. GNR@SWCNT at an elevated temperature is easier to break during torsion with a lower twist angle. The results are valuable for the design of nanocomposites composed of carbon nanotubes and graphene materials.

In this study, the effects of calcination temperature on the characteristics of tungsten trioxide (WO3) nanofibers over time were explored. The objective being to observe the effects of calcination temperature and time of exposure on nanofibers when the voltage, work flow rate, and the pinhead used in the process were all fixed. The results showed that when the calcination temperature was increased to 550 °C, fiber structure was damaged. The nanofibers showed the selectivity about 9% at 360 ppm of ethanol gas. The response of ethanol will increase when the concentration increase.

The nanoforging process and mechanism of pure aluminum samples is studied using molecular dynamics (MD) simulations based on embedded atom method (EAM) potential function. The effects of the forging temperature and the forging velocity are evaluated in terms of molecular trajectories, internal energy, and a radial distribution function. The simulation results clearly show that the internal energy of the workpiece exerted on it during the forging process have high energy with decreasing forging temperature ; however, with increasing forging velocity, the internal energy have higher energy. During the forging process, a special atomic structure in (011) and (0) slip planes was observed, and that represents the site of generation of dislocation and growth nucleation. When severe plastic deformation occurs, the density of the workpiece varied. The forged workpiece has similar distributions of atomic density after the loading for various forging temperatures and forging velocities.

Anti-reflection based on the mimicking of moth eye subwavelength structures (SWSs) has several advantages over conventionally used multilayer thin film antireflective coatings like broad angular and spectral responses, polarization insensitivity and improved stability. In this study, we present the low cost fabrication of moth eye based SWSs on flexible polyethylene terephthalate (PET) substrate using Roll-to-Roll Ultraviolet Nanoimprint Lithography (UV-NIL). We have used a novel method to create a roller mold with embedded nanopores that can be used for easy replication of SWSs without demolding issues. Pure aluminum foil was wrapped around an acrylic cylinder (O = 90mm) and a multistep anodizing and pore widening scheme was employed to create well-ordered and periodic anodized aluminum oxide (AAO) nanopores with different aspect ratios. Optical characterization of the antireflective PET film shows a transmittance over 92 %, an increase of 3% as compared to bare PET, while reflectance can be reduced from 5.3% to 0.09% in the range of visible light. It was observed that higher aspect ratio SWSs is more effective in reducing reflections at higher incident angles. Consequently, we have demonstrated an economically feasible method for fabricating large area polymer films that can be used to reduce light reflections which impose severe limitations on the performance of many optoelectronic devices like solar cells, photodetectors and flat display panels.

In this article, we analyze the sensitivity of lateral, axial, and torsional vibration of a scanning near-field optical microscope (SNOM) probe. An exact solution for the title problem is obtained using the theory of beam and torsional vibrations. Sensitivities are obtained for a wide range of the intervening physical parameters. This paper discusses the relationship between the sensitivity of a SNOM probe and its geometry. The analysis is presented for a probe in three different cases lateral vibration, axial vibration, and torsional vibration, for a fixed-free configuration. To derive the mathematical relation between the probe and sample (by utilizing springs and damping to simulate different environments) through the process of theory analysis for different environments. Thus a universal touchless SNOM probe sensitivity controller is developed for appropriate control and adjustment of the probe sensitivity suitable under different environments. Such controller helps the SNOM probe achieve the nanoscale resolution through proper control and adjustment probe sensitivity in accordance to changes to different environments and reduce the chance of being damaged during the scan, which in the end further advances the sample inspection technique.

This paper studies the effects of different gas compositions on the growth of multi-walled carbon nanotube (MWCNT) films by using an electron cyclotron resonance chemical vapor deposition (ECR-CVD) method. The Raman spectrum was employed to explore the composition of the MWCNT films grown under different mixtures of C3H8 and H2. The results showed that the optimum relative intensity ratio of the D band to G band (i.e., ID/IG) is 2 for the cases considered in this study. In addition, the morphology and microstructure of the MWCNTs were examined by field emission scanning electron microscopy (FE-SEM) and field emission gun transmission electron microscopy (FEG-TEM). Furthermore, atomic force microscopy (AFM) and scanning thermal microscopy (SThM) were used to study the surface topography and thermal properties of the MWCNTs.

This paper presents a new approach for the synthesis of spherical four-bar mechanisms with two or three prescribed coupler curve cusps. According to the configuration of a spherical four-bar mechanism whose coupler point coincides with the instant center at two separated positions, two kinds of degenerated curves for the corresponding spherical Burmester curves are obtained. For each degenerated curve, a synthesis procedure is proposed for the dimensional synthesis of spherical four-bar mechanisms to trace a coupler curve with two prescribed cusps. The possible types of spherical four-bar mechanisms with two-cusp coupler curves are discussed. Furthermore, special spherical double-rockers are also presented for tracing a symmetric coupler curve with two cusps, tracing a doubly symmetric coupler curve with two cusps or tracing a symmetric coupler curve with three cusps.

In this paper, an analytic treatment to investigate the Burmester curves of the PPP-P case in spherical motion is presented. With a rotation angle of a coupler about a pole and an instant centre associated with an inflection point specified, a geometric construction is established to determine the corresponding spherical centre-points and circle-points. According to the geometric construction, the explicit equations of spherical Burmester curves for the PPP-P case are directly derived by using spherical trigonometry, without the use of differential technique. The explicit equations obtained give a clear insight into the geometric properties and special cases of the spherical Burmester curves, which include degenerated curves and symmetric curves. A design application is presented.

This paper presents an analytic treatment to investigate the Burmester curves of the PPP-P case. Provided that an instant center associated with an inflection point and rotation angle of a coupler about a pole are specified, the explicit equations of Burmester curves for the PPP-P case are directly derived without any differential process. Because the explicit equations derived are of quadratic form, their geometric properties can be easily investigated. Six degenerated cases and three special cases of the Burmester curves for the PPP-P case are obtained. A design example is presented.

In this paper an analytic method to investigate the degenerated spherical Burmester curves of the PP-P-P case is presented. (Provided that an instant centre and two poles associated with two rotation angles of a coupler are specified, a geometric construction is established to determine the spherical centre- and circle-point.) According to the geometric construction, the explicit equations of spherical Burmester curves for the PP-P-P case are thus derived, without the use of differentiation, but by using spherical cross ratio. By assigning proper parameter values to equations obtained, six types of degenerated spherical Burmester curves of the PP-P-P case are obtained directly, which include three different forms of the degenerated curve: (1) a point, (2) a great circle and a spherical Thales ellipse and (3) three great circles.

A new method is proposed to derive the special cases that the center- and circle-point curves of PP-PP multiply separated positions degenerate into the combinations of points, lines and circles. Analytical equations for the construction of the Burmester curves are presented in a simpler form with four parameters. All conditions that yield degenerate forms of the equations are concluded by investigating the parameters. Degenerate Burmester curves are then thoroughly derived from various combinations of the conditions. The results of this work are more complete than existing papers, and presented concisely in tables. Applications of the degenerate curves are also illustrated by an example.

With a pole and two instant centres specified on a unit sphere, a geometrical construction is proposed to determine the spherical centre- and circle-points. The explicit equations of the corresponding spherical centre- and circle-point curves of the PP-PP case are thus obtained by using spherical trigonometry. All break-ups of these spherical centre- and circle-point curves are directly generated from the explicit equations. Through an exhaustive search, it was found that there are four kinds of degenerated curves, i.e. (1) two points and a great circle, (2) two spherical ellipses and a great circle, (3) three orthogonal great circles and (4) a sphere. Two design examples are presented.

In this paper we present analogies between planar and spherical four-bar linkages with symmetrical coupler-curves. Three types of planar four-bar linkages with symmetrical coupler-curves are investigated. For spherical linkages in contrast to these planar four-bar linkages, two types of them generate symmetrical coupler-curves, and so does the remaining one if it has special dimensions.

We present a geometric method for structural synthesis of planar five-bar pantograph configurations. Based on the concept of similarly varying triangles, the geometric conditions for a five-bar linkage to be a pantograph are derived according to a complex number approach. Under these conditions, a geometric procedure is proposed to synthesize all five-bar pantograph configurations with four or three similarity points systematically. In total 13 configurations with four similarity points and 23 configurations with three similarity points are obtained. The results of this work provide a complete atlas of pantograph configurations superior to existing ones.

In this paper a cross ratio theory applied in sphere geometry and its application on the spherical mechanism is presented. By expanding the cross ratio concept in plane geometry, cross ratio is proved to be equally valid in sphere geometry. Then, an alternative form of spherical cross ratio is proposed. An application of spherical cross ratio for the design of spherical four-bar mechanisms is presented.

Vertical shaft type wind-power Chinese square-pallet chain-pumps are Chinese square-pallet chain-pumps that are powered by vertical-sail-type Chinese windmills (Chinese great windmills). These apparatuses had been widely-used for raising water in agricultural fields and salt fields along the coast of China since the 12th century until the 1980s, when they went completely extinct. While there is a lack of detailed records of the techniques and craftsmanship used in building these chain-pumps, there still survive some master craftsmen who are skilled in designing and building them, though most of them are quite old. Following a plan for their revival, we have successfully preserved the dying technique and craftsmanship. This article is an analysis of the mechanisms of these chain-pumps and the principles underlying their functionality based on our reconstruction research.