A new linear integration for plastic power was proposed.The effective strain rate for disk forging with bulge was expressed in terms of two-dimensional strain rate vector,and then its direction cosines were determined...A new linear integration for plastic power was proposed.The effective strain rate for disk forging with bulge was expressed in terms of two-dimensional strain rate vector,and then its direction cosines were determined by the ratio of coordinate increments.Furthermore,inner-product of the vector for plastic power was term integrated by term and summed.Thereafter,through a formula for determination of bulge an analytical solution of stress effective factor was obtained.Finally,through compression tests,the calculated results of above formula were compared with those of Avitzur’s approximate solution and total indicator readings of the testing machine.It is indicated that the calculated compression forces are basically in agreement with the measured ones if the pass reduction is less than 13.35%.However,when the reduction gets up to 25.34% and 33.12%,the corresponding errors between the calculated and measured results also get up to 6% and 13.5%,respectively.展开更多
A new linear integration was developed. First, effective strain rate for slab forging with bulge was expressed in terms of two-dimensional strain rate vector, and its inner-product was integrated term by term. Second,...A new linear integration was developed. First, effective strain rate for slab forging with bulge was expressed in terms of two-dimensional strain rate vector, and its inner-product was integrated term by term. Second, a summation process of term by term integrated results and a formula of the bulging were introduced, and an analytical solution of stress effective factor was obtained. It is proved that the expression of power by the above linear integration is the same as that of traditional immediate integration. Also, the solution was simplified by series expansion and compared by slab forging test with the others. It turns out that the calculated result of total forging pressure is basically in agreement with measured value in the actual press test.展开更多
A novel algorithm for skeleton extraction is proposed in the paper. By numbering object's border elements on spatial position, the border gap (BG) of inner pixel of the object is calculated; an 8-connected medial-...A novel algorithm for skeleton extraction is proposed in the paper. By numbering object's border elements on spatial position, the border gap (BG) of inner pixel of the object is calculated; an 8-connected medial-axis hierarchy is derived by the BG; a thinning method including slicing and counting is proposed to improve the processing speed; branches with minor importance are truncated by vector diversity Vd and length-width ratio (LWR) with support vector machine (SVM) classifier. Experiments demonstrate that the derived skeletons keep good connectivity, especially in long and narrow area.展开更多
函数加密作为一种多功能的新型公钥加密原语,因其能实现细粒度的密文计算,在云存储中有着广阔的应用前景,受到研究者们的广泛研究.因此,将数据的访问权限控制有机地融合到加解密算法中,实现“部分加解密可控、按需安全计算”是一个非常...函数加密作为一种多功能的新型公钥加密原语,因其能实现细粒度的密文计算,在云存储中有着广阔的应用前景,受到研究者们的广泛研究.因此,将数据的访问权限控制有机地融合到加解密算法中,实现“部分加解密可控、按需安全计算”是一个非常有意义的探索方向.但现有函数加密方案无法精细控制发送者权限且使用了较复杂的理论工具(如不可区分性混淆、多线性映射等),难以满足一些特定应用场合需求.面对量子攻击挑战,如何设计抗量子攻击的特殊、高效的函数加密方案成为一个研究热点.内积函数加密是函数加密的特殊形式,不仅能够实现更复杂的访问控制策略和策略隐藏,而且可以有效地控制数据的“部分访问”,提供更细粒度的查询,在满足数据机密性的同时提高隐私保护.针对更加灵活可控按需安全计算的难点,该文基于格上Learning with errors困难问题提出一种基于身份的细粒度访问控制内积函数加密方案.该方案首先将内积函数与通过原像抽样算法产生的向量相关联,生成函数私钥以此控制接收方的计算能力.其次,引入一个第三方(访问控制中心)充当访问控制功能实施者,通过剩余哈希引理及矩阵的秩检验密文的随机性,完成对密文的重随机化以实现控制发送者权限的目的.最后,接收者将转换后的密文通过内积函数私钥解密,仅计算得到关于原始消息的内积值.理论分析与实验评估表明,所提方案在性能上有明显优势,不仅可以抵御量子攻击,而且能够控制接收者的计算权限与发送者的发送权限,在保护用户数据机密性的同时,有效实现开放环境下数据可用不可见、数据可算不可识的细粒度权限可控密文计算的目标.展开更多
基金Project(50474015) supported by the National Natural Science Foundation of China
文摘A new linear integration for plastic power was proposed.The effective strain rate for disk forging with bulge was expressed in terms of two-dimensional strain rate vector,and then its direction cosines were determined by the ratio of coordinate increments.Furthermore,inner-product of the vector for plastic power was term integrated by term and summed.Thereafter,through a formula for determination of bulge an analytical solution of stress effective factor was obtained.Finally,through compression tests,the calculated results of above formula were compared with those of Avitzur’s approximate solution and total indicator readings of the testing machine.It is indicated that the calculated compression forces are basically in agreement with the measured ones if the pass reduction is less than 13.35%.However,when the reduction gets up to 25.34% and 33.12%,the corresponding errors between the calculated and measured results also get up to 6% and 13.5%,respectively.
文摘A new linear integration was developed. First, effective strain rate for slab forging with bulge was expressed in terms of two-dimensional strain rate vector, and its inner-product was integrated term by term. Second, a summation process of term by term integrated results and a formula of the bulging were introduced, and an analytical solution of stress effective factor was obtained. It is proved that the expression of power by the above linear integration is the same as that of traditional immediate integration. Also, the solution was simplified by series expansion and compared by slab forging test with the others. It turns out that the calculated result of total forging pressure is basically in agreement with measured value in the actual press test.
文摘A novel algorithm for skeleton extraction is proposed in the paper. By numbering object's border elements on spatial position, the border gap (BG) of inner pixel of the object is calculated; an 8-connected medial-axis hierarchy is derived by the BG; a thinning method including slicing and counting is proposed to improve the processing speed; branches with minor importance are truncated by vector diversity Vd and length-width ratio (LWR) with support vector machine (SVM) classifier. Experiments demonstrate that the derived skeletons keep good connectivity, especially in long and narrow area.
文摘函数加密作为一种多功能的新型公钥加密原语,因其能实现细粒度的密文计算,在云存储中有着广阔的应用前景,受到研究者们的广泛研究.因此,将数据的访问权限控制有机地融合到加解密算法中,实现“部分加解密可控、按需安全计算”是一个非常有意义的探索方向.但现有函数加密方案无法精细控制发送者权限且使用了较复杂的理论工具(如不可区分性混淆、多线性映射等),难以满足一些特定应用场合需求.面对量子攻击挑战,如何设计抗量子攻击的特殊、高效的函数加密方案成为一个研究热点.内积函数加密是函数加密的特殊形式,不仅能够实现更复杂的访问控制策略和策略隐藏,而且可以有效地控制数据的“部分访问”,提供更细粒度的查询,在满足数据机密性的同时提高隐私保护.针对更加灵活可控按需安全计算的难点,该文基于格上Learning with errors困难问题提出一种基于身份的细粒度访问控制内积函数加密方案.该方案首先将内积函数与通过原像抽样算法产生的向量相关联,生成函数私钥以此控制接收方的计算能力.其次,引入一个第三方(访问控制中心)充当访问控制功能实施者,通过剩余哈希引理及矩阵的秩检验密文的随机性,完成对密文的重随机化以实现控制发送者权限的目的.最后,接收者将转换后的密文通过内积函数私钥解密,仅计算得到关于原始消息的内积值.理论分析与实验评估表明,所提方案在性能上有明显优势,不仅可以抵御量子攻击,而且能够控制接收者的计算权限与发送者的发送权限,在保护用户数据机密性的同时,有效实现开放环境下数据可用不可见、数据可算不可识的细粒度权限可控密文计算的目标.
