Singularity and workspace analysis of three isoconstrained parallel manipulators with schoenflies motion

This paper presents the analysis of three parallel manipulators with Schoenflies-motion. Each parallel manipulator possesses two limbs in structure and the end-effector has three DOFs (degree of freedom) in the translational motion and one DOF in rotational motion about a given direction axis with respect to the world coordinate system. The three isoconstrained parallel manipulators have the structures denoted as CuuUwHw-//-CvvUwHw, CuRuuUhw-//-CvRvvUhw and CuPuUhw-//- CvPvUhw. The kinematic equations are first introduced for each manipulator. Then, Jacobian matrix, singularity, workspace, and performance index for each mechanism are subsequently derived and analysed for the first time. The results can be helpful for the engineers to evaluate such kind of parallel robots for possible application in industry where pick-and-place motion is required.     

Scrutiny of non-linear differential equations Euler-Bernoulli beam with large rotational deviation by AGM

The kinematic assumptions upon which the Euler-Bernoulli beam theory is founded allow it to be extended to more advanced analysis. Simple superposition allows for three-dimensional transverse loading. Using alternative constitutive equations can allow for viscoelastic or plastic beam deformation. Euler-Bernoulli beam theory can also be extended to the analysis of curved beams, beam buckling, composite beams and geometrically nonlinear beam deflection. In this study, solving the nonlinear differential equation governing the calculation of the large rotation deviation of the beam (or column) has been discussed. Previously to calculate the rotational deviation of the beam, the assumption is made that the angular deviation of the beam is small. By considering the small slope in the linearization of the governing differential equation, the solving is easy. The result of this simplification in some cases will lead to an excessive error. In this paper nonlinear differential equations governing on this system are solved analytically by Akbari-Ganji’s method (AGM). Moreover, in AGM by solving a set of algebraic equations, complicated nonlinear equations can easily be solved and without any mathematical operations such as integration solving. The solution of the problem can be obtained very simply and easily. Furthermore, to enhance the accuracy of the results, the Taylor expansion is not needed in most cases via AGM manner. Also, comparisons are made between AGM and numerical method (Runge-Kutta 4th). The results reveal that this method is very effective and simple, and can be applied for other nonlinear problems.     

Fracture limits of sheet metals under stretch bending

Fracture limits in sheet stretch bending were theoretically obtained on the assumption that the fracture occurs when the stretching force reaches its maximum value. From the calculated results, a fracture criterion has been presented where limit wall stretch, L_max/L₀ (L_max: limit wall length of a sheet, L₀: initial wall length), is explicitly given as a function of the non-dimensional bending curvature, t₀/R (t₀: sheet thickness, R: bending radius) and the material's work hardening exponent (n-value). To verify this criterion, three-point stretch bending tests with various punch-radii were performed on three types of aluminum sheets (A5182-O, JIS6061-T4 and JIS6N01-T5). The predicted limit wall stretch, as well as limit forming height, were in good agreement with the experimental results.     

Acoustical properties of a long rectangular cavity of constant cross-section immersed in a thick boundary layer

An experimental investigation was undertaken to examine the effect of cavity length on flow oscillations produced by an open cavity placed within a subsonic turbulent boundary layer. A narrow rectangular cavity with a constant width to depth ratio, W/D, of 1 was placed within a thick fully developed turbulent boundary layer with a corresponding Re_θ=10.5×10³. Pressure time histories were acquired for six separate cavity lengths (or L/D values) using microphone type pressure transducers. The spectral character of these signals was analyzed in terms of their magnitude and frequency content. This study indicates that large changes in the fluctuating pressure level can occur as L/D is varied from 1.47 to 8.73. A state of acoustic resonance was only observed at L/D=1.47, while fluid-acoustic resonance occurred at L/D between 1.47 and 8.73. Relative SPL calculations indicate that energy within the cavity was increased by approximately 60% over this L/D range. It is also suggested that this increase was a result of vortical structure shedding and growth. In addition, the location of maximum unsteadiness was estimated to coincide with the location of vortical structure saturation.     

Free transverse vibration of elliptical plates of variable thickness with half of the boundary clamped and the rest free

First four frequencies have been computed for an elliptical plate half of whose boundary (y0) is clamped and the other half is free. The thickness of the plate is taken varying linearly with space coordinates. The Rayleigh–Ritz method has been used to obtain successive approximations utill convergence is achieved up to at least four significant figures. Results are tabulated for various values of the taper parameters. Three-dimensional mode shapes and the associated contour lines have been plotted in some selected cases. A table showing the rate of convergence with increasing order of approximation is given. Comparison has been made with known results in special cases. For the sake of completeness, results for the cases when the entire boundary is clamped or completely free are also reported.     

Dissociation of basal dislocations in hexagonal barium titanate

Dislocation substructure in hot-pressed hexagonal BaTiO₃ ceramics was analysed by transmission electron microscopy. Two dislocation networks each consisting of dissociated half-partials were determined for the Burgers vectors ( b ) using the g · b  = 0 effective invisibility criteria, and the true directions ( u ) by trace analysis. Each of the networks contains three partial nodes that are in the form: 1/3[010]+1/3[100]+1/3[100]+1/3[100] = 0, where four partials meet at a point and the Burgers vectors are conserved, as analysed by the weak-beam dark field technique. Basal dislocation with b _b = 1/3<110> is dissociated into two prism plane half-partials with b _hp = 1/3<100> by: 1/3<110> → 1/3<010> + 1/3<100>. Dissociation of basal dislocation by a glide mechanism creates a stacking fault when shear occurs along <100> in the c-layer of (000l), where l = 1, 3, 4 and 6, of the (chc)₁(chc)₂ (or (CBC)(ABA)) stacking sequence. The slip system of 1/3<110>(0001) in hexagonal BaTiO₃ has been activated at 1300 °C by hot-pressing under ∼25.8 MPa. Plastic flow contributing to the densification of hexagonal BaTiO₃ ceramics occurs through glide of half-partials in the basal plane by a glide-controlled dislocation glide mechanism. Dislocation motion governed by the Peierls mechanism, where velocity is determined by both correlated and uncorrelated double-kink nucleation on two half-partials, is discussed.     

Image matching between experimental and simulated high‐resolution electron micrographs of sapphire on the orientation

The effects of imaging parameters have been studied on their roles of the severe mismatches between experimental and simulated high‐resolution transmission electron micrographs of sapphire along the direction. Image simulation and convergent‐beam electron diffraction techniques have been performed on misalignments of the electron beam and the crystal specimen. Based on this study, we have introduced an approach to achieve reliable simulation for experimental images of sapphire on the projection by the use of iterative digital image matching.     

Thermally induced vibration of a thermal sleeve with the GDQ method

The generalized differential quadrature (GDQ) method is used to obtain the numerical results of two-layer cross-ply laminated tubes under thermal vibration. Piping components in the electric power industry should be understood and designed to resist the thermal fatigue cracking. In the analyses of the thermally induced vibration of a thermal sleeve under linear temperature load ΔT, the computational GDQ method provides a method for calculating the natural frequency, displacement and thermal stress.     

Reverse flow in a circular duct with an obstruction at the entry

In this paper the reverse flow in a duct (diameter D) with an obstruction at the front (which is a disc), is investigated using PIV. The gap g between the obstruction and the entry to the duct is systematically varied and it is found that maximum reverse flow occurs at a g/D value of 0.5. The flow is stagnant around g/D of 1.25 and forward flow occurs for g/D values of 1.5 and above. The vortex formation length behind the disc is smaller than that of the plate and the variation of the magnitude of reverse flow with the gap g between the axisymmetrical circular duct and two-dimensional channel differs considerably. The reverse flow phenomena in the circular duct with an obstruction at the entry can be explained by the vortex formation length and low pressure behind the obstruction.     

The Third Invariant Form of Hydrodynamic Equations and Application for Definition of Water Hammer Characteristics in Pipe

There were for a long time two invariant forms of hydrodynamic equations： one was related to coordinate system of references, and the other was versus to measure units of characteristics. These both invariant forms had important roles in the development of theoretical and practical applications of hydro-aerodynamics and related industries. The third invariant form of hydrodynamic equations is one for the dimensions of spaces. For this goal, the hyper quantities （space and physics） are introduced. Then these are created we can easily cover all problems in arbitrary dimensions （3D, 2D, 1D, separate space for liquids or constituent matters）. In particularly, when they are applied to water hammer problem, which is an especially problem, we can receive immediately celerity and pressure of the event.     

Estimation of length density Lv from vertical slices of unknown thickness

Length density of lineal features, L_v, is an important stereological parameter. The efficient stereological procedure for the estimation of L_v from the counting measurement performed on the projected images of the vertical slices (foils) is modified and improved: L_v can be now estimated from vertical slices of unknown thickness, and the slices need not be of the same thickness. The required assumption-free stereological relationship is is the average number of intersections of straight test lines parallel to the vertical axis with the projected images of the lineal features in the vertical slices, per unit test line length. is the average number of intersections of the lineal features with the parallel planes of the vertical slices, per unit area. Note that there are two parallel planes in a slice, and therefore their total area is twice the area of the observed projected image frame. is the average number of intersections of orientated cycloid-shaped test lines (minor axis perpendicular to vertical axis) with the projected images of the lineal features in the vertical slices, per unit length. For practical applications of this result, it is necessary uniquely to identify the points of intersections of the lineal features with the parallel planes of the slices in the projected images, so that can be estimated unambiguously. However, in practice, this is not a problem in biological, as well as materials microstructures.     

岩茶水库岭肉桂中原花青素的高效液相色谱-串联质谱法分析

采用高效液相色谱 串联质谱技术,多重反应监测模式对岩茶水库岭肉桂样品中的原花青素组分进行定性和定量分析。采用Waters SunFire-C₁₈柱（150 mm×2.1 mm×5 μm）,流动相为乙腈和0.1%甲酸水溶液,流速0.25 mL/min,柱温25 ℃,进样量3 μL。结果表明,岩茶水库岭肉桂样品中的原花青素主要有儿茶素、表儿茶素、表儿茶素没食子酸酯和原花青素B₂,其回归方程和相关系数分别为： y₁=642.48x-63.693,r=0.999 5;y₂=550.45x+10.386,r=0.999 6;y₃=2 261.5x-1 320.0,r=0.999 5和 y₄=4 598.5x-4 079.0,r=0.999 5;其线性范围为5.00～150.00 mg/L。方法的加标回收率为93.9％～108.0％,变异系数小于7.53％,最低检出限为0.005 5～0.013 2 μg/g。     

Development of Technology and Method for Phosphoproteome and Glycoproteome Analysis

The elucidation of protein post-translational modifications, such as phosphorylation, remains a challenging analytical task for proteomic studies. Since many of the proteins targeted for phosphorylation are low in abundance and phosphorylation is typically substoichiometric, a prerequisite for their identification is the specific enrichment of phosphopeptide prior to mass spectrometric analysis. A new type of the immobilized metal ion affinity chromatography (IMAC) through the chelating interaction between phosphate groups on the polymer and Zr^4＋ and Ti^4＋ (Zr^4＋- and Ti^4＋-IMAC) has been developed for enriching phosphopeptides. We also compared Zr^4＋- and Ti^4＋-IMAC to other enrichment methods including Fe^3＋-IMAC, TiO₂ and ZrO₂, and demonstrate superior selectivity and efficiency of Zr^4＋- and Ti^4＋-IMAC for the isolation and enrichment of phosphopeptides. Furthermore, a new approach was established by integration of the enrichment of phosphopeptides with Ti^4＋-IMAC and peptide fractionation with strong cation-exchange (SCX) column for large-scale phosphoproteome analysis of human liver, and about 10 000 phosphorylation sites were detected. Compared with large scale phosphorylation analysis at proteome level, comprehensive and reliable phosphorylation site mapping of individual phosphoprotein is equally important. A novel method for confident phosphorylation site analysis of individual phosphoproteins was developed without manual interpretation of spectra. Phosphopeptides enriched from tryptic digests of phosphoproteins were analyzed by nano-LC-MS²/MS³, and the acquired MS² and MS³ spectra in valid MS²/MS³ pairs were searched against the composite database separately. This methodology combined with multi-protease digestion approach was applied to analyze the phosphorylation of the standards phosphoproteins and cyclic AMP dependent protein kinases. In silico digestion of proteins in human proteome database by trypsin indicates that a significant percentage of tryptic N-glycopeptides is not in the preferred detection mass range of shotgun proteomics approach, that is, from 800 to 3 500 Da. And the quite big size of glycan groups may block trypsin to access the K, R residues near N-glycosites for digestion, which will result in generation of big glycopeptides. Thus many N-glycosites could not be localized if only trypsin was used to digest proteins. We developed a comprehensive way to analyze the N-glycoproteome of human liver tissue by combination of hydrazide chemistry method and multiple enzyme digestion, which leads to great improvement in coverage of N-glycosites identified.相似文献   

Manipulators: Execution of prescribed trajectories special link positions and versions of assembly

A new technique for the kinematical analysis and design of manipulators based on the following principles is proposed:

• 1.(1) Link positions are determined by subsystems of equations which contain a reduced number of unknowns and may be solved separately. The derivation of such systems of equations may be based: (a) on the modeling of the manipulator by two open chains or (b) on modified closure matrix equations.
• 2.(2) Special 4 × 4 matrices which describe separately the link geometry and the relative motion of links are applied.
• 3.(3) All potential configurations which are formed by the manipulator links may be determined using the information on special link positions.
• 4.(4) Angles of rotation in the joints are determined as functions of the trajectory parameters using a system of six nonlinear equations represented in echelon shape.

The above techniques are applied for the kinematical analysis of a Cincinnati Milacron T3 manipulator with six degrees-of-freedom. A computer program for the control of rotations in the joints has been developed based on these techniques, and the results are presented at the end of this paper.