Multi-stage optimum design of magazine type automatic tool changer arm

To enhance machining efficiency,tool change time has to be reduced.Thus,for an automatic tool changer attached to a machining center,the tool change time is to be reduced.Also the automatic tool changer is a main part of the machining center as a driving source.The static attributes of the automatic tool changer using the commercial code,ANSYS Workbench V12,were tried to interpret.And the optimum design of automatic tool changer arm was proposed by performing the multi-stage optimum design.The shape optimization of the automatic tool changer was proposed and the result was verified to obtain acceptable improvements.It is possible to obtain an optimized model in which the maximum deformation,maximum stress,and mass are reduced by 10.46%,12.89% and 9.26%,respectively,compared with those of the initial model.Also,the results between conventional method by the design of experiments and proposed method by the multi-stage optimum design method were compared.

Automatic Search of Impossible Differentials and Zero-Correlation Linear Hulls for ARX Ciphers

In lightweight cryptographic primitives, round functions with only simple operations XOR, modular addition and rotation are widely used nowadays. This kind of ciphers is called ARX ciphers. For ARX ciphers, impossible differential cryptanalysis and zero-correlation linear cryptanalysis are among the most powerful attacks, and the key problems for these two attacks are discovering more and longer impossible differentials(IDs) and zero-correlation linear hulls(ZCLHs). However, finding new IDs and ZCLHs for ARX ciphers has been a manual work for a long time, which has been an obstacle in improving these two attacks. This paper proposes an automatic search method to improve the efficiency of finding new IDs and ZCLHs for ARX ciphers. In order to prove the efficiency of this new tool, we take HIGHT, LEA, SPECK three typical ARX algorithms as examples to explore their longer and new impossible differentials and zero-correlation linear hulls. To the best of our knowledge, this is the first application of automatic search method for ARX ciphers on finding new IDs and ZCLHs. For HIGHT, we find more 17 round IDs and multiple 17 round ZCLHs. This is the first discovery of 17 round ZCLHs for HIGHT. For LEA, we find extra four 10 round IDs and several 9 round ZCLHs. In the specification of LEA, the designers just identified three 10 round IDs and one 7round ZCLH. For SPECK, we find thousands of 6 round IDs and forty-four 6 round ZCLHs. Neither IDs nor ZCLHs of SPECK has been proposed before. The successful application of our new tool shows great potential in improving the impossible differential cryptanalysis and zero-correlation linear cryptanalysis on ARX ciphers..

A brief review on the strategy for selection of orthology prediction methods in phylogenomic studies

With the development and decreasing cost of sequencing techniques, it is possible for scientists to conduct deeper research in phylogenomics. During the procedure of phylogenomic analysis, the mostimportant and vitalest step is orthology prediction, for that the prerequisite to phylogenetic reconstruction is that the genes being compared are orthologous. Here we briefly review the related concept of orthology anddifferent methods for orthology prediction. We also provide recommendations to give some advice for better selection of orthology prediction methods.

A new design of automatic vertical drilling tool

In order to effectively improve penetration rates and enhance wellbore quality for vertical wells,a new Automatic Vertical Drilling Tool(AVDT)based on Eccentric Braced Structure(EBS)is designed.Applying operating principle of rotary steering drilling,AVDT adds offset gravity block automatic induction inclination mechanism.When hole straightening happens,tools take essentric moment to be produced by gravity of offset gravity lock to control the bearing of guide force,so that well straightening is achieved.The normal tool's size of the AVDT is designed as 215.9 mm,other major components'sizes are worked out by the result of theoretical analysis,including the offset angle of EBS.This paper aims to introduce the structure,operating principle,theoretical analysis and describe the key components'parameters setting of the AVDT.