Sawing Performance Comparison of Brazed and Sintered Diamond Wires

Great attention has been paid on fabricating diamond wire by using the brazing diamond because of its strong chemical bonding strength and controllability of grits distribution. Although several serving performances of brazed diamond wire have been reported, seldom do these studies refer to its process characteristics. Sawing performances of a brazed diamond wire are investigated and compared with those of a sintered diamond wire on a wire saw machine. The surface topographies of beads selected from the two wires are micro observed before sawing. The sawing tests are carried out in constant feed rate feeding（CFF） and constant normal force feeding（CNFF）. In CFF test, sawing force, power, and the cut depths of positions on contact curve are measured. Then, coupled with the observations of beads topographies, sawing force and its ratio, relations of power against material removal rate, and contact curve linearity are compared and discussed. In CNFF test, the sawing rates of the two wires are investigated. The results indicate that the brazed wire performs with lower sawing force（less 16% of tangential force and 28% of normal force）, more energy efficiency（nearly one-fifth of sawing power is saved）, at a higher sawing rate （the rate is doubled） and with better contact curve linearity as compared with the sintered wire. This proposed research experimentally evaluates the sawing performances of brazed diamond wire from the aspect of process parameters, which can provide a basis for popularizing the brazed diamond wire.

Generating Parametric G^n Blending Surface with Some Constraints

This paper presents a method of generating a parametric G^n blending surfacebased on reparameterizing the partial surface patches in the base surfaces on the basis of ErichHartmann method. This method is expressed as follows Firstly, the partial region near contact curvesin both base surfaces is reparameterized. The contact curves are used as the boundaries of thereparameterized partial region respectively. The reparameterized partial region in two base surfacesis called the reparameterized local base surfaces. Then the parametric G^n blending surface isgenerated by a linear combination of the reparameterized local base surface patches depending on oneof the common parameters. Therefore, generating a Parametric G^n Blending Surface between two basesurfaces is translated into generating a Parametric G^n Blending Surface between the tworeparameterized local base surfaces. This paper illustrates the method to generate the G^n blendingsurface with some constraints by generating a G^2 blending surface between the aerofoil and the bodyof a missile with the constraints of the forward and rear fringe curves. When the G^n blendingsurface with some constraints is generated, the partial region near contact curves in both basesurfaces is reparameterized, and the scale factors, offset, balance factor and thumb weight aredefined by meeting the constraints through using an optimization method. Then the parametric G^nblending surface is generated by the linear combination of the reparameterized local base surfacepatches. The shape of the blending surface can be adjusted by changing the size of thereparameterized local base surface patches.

STUDY ON THE UNIQUENESS OF LIMIT CYCLE OF THE QUADRATIC SYSTEM BY USING THE QUADRATIC CURVE WITHOUT CONTACT(CONTINUED 1)

In this paper, we continue to discuss the uniqueness of limit cycle of the quadratic system by using the quadratic curve without contact and several new criteria for the uniqueness have been obtained.

Local buckling of thin plate on tensionless elastic foundations under interactive uniaxial compression and shear

This paper uses a mathematical method to develop an analytical solution to the local buckling behaviour of long rectangular plates resting on tensionless elastic Winkler foundations and under combined uniform longitudinal uniaxial compressive and uniform in-plane shear loads. Fitted formulas are derived for plates with clamped edges and simplified supported edges. Two examples are given to demonstrate the application of the current method： one is a plate on tensionless spring foundations and the other is the contact between the steel sheet and elastic solid foundation. Finite element （FE） analysis is also conducted to validate the analytical results. Good agreement is obtained between the current method and FE analysis.

Accuracy and safety of partial thickness femtosecond laser radial and arcuate keratotomy incisions in porcine eyes

Background:To evaluate the accuracy and safety of micro radial and arcuate keratotomy incisions constructed by a femtosecond laser system with a curved contact patient interface in porcine eyes.Methods:Partial thickness micro radial and arcuate keratotomy incisions were constructed in porcine eyes with a femtosecond laser system and evaluated for precision of depth,quality,and consistency.Optical coherence tomography was used to determine the accuracy and precision of incision depth.Corneal endothelial safety was assessed by a fluorescent live/dead cell viability assay to demonstrate laser-induced endothelial cell loss.Quality was evaluated by ease of opening and examination of interfaces.Results:In two micro radial incision groups,intended incision depths of 50%and 80%resulted in mean achieved depths of 50.01%and 77.69%,respectively.In three arcuate incision groups,intended incision depths of 80%,600μm or 100μm residual uncut bed thickness resulted in mean achieved depths of 80.16%,603.03μm and residual bed of 115μm,respectively.No loss of endothelial cell density occurred when the residual corneal bed was maintained at a minimum of 85-116μm.The incisions were easy to open,and interfaces were smooth.Conclusions:A femtosecond laser system with curved contact interface created precise and reproducible micro radial and arcuate keratotomy incisions.Accuracy and precision of the incision depth and preservation of endothelial cell density demonstrated the effectiveness and safety of the system.