变幅杆连接工艺对旋转超声加工质量影响的研究

超声旋转加工是一种适用于脆硬材料加工的新技术,它强化了原加工过程,其加工效率随着材料脆性的增大而提高,实现了低耗能的目标。在超声旋转加工中,超声加工工具与变幅杆的连接对超声振动共振频率和超声波加工性能有很大影响。本文在深入研究旋转超声加工基本原理的基础上,分析了旋转超声加工时能量传递系统的关键制件-变幅杆和工具杆对超声加工精度的影响,并对变幅杆和工具杆制造工艺及连接的方法进行了初步研究。     

Horn equational theories and paramodulation

A language of equational programs together with an inference system, based on paramodulation is defined. The semantics of the language is given with respect to least models, least fixpoints and success sets and its soundness and completeness is proven using fixpoint theory. The necessity of the functional reflexive axioms is investigated in detail. Finally, the application of these ideas to term rewriting systems is outlined by discussing directed paramodulation and narrowing.     

Horn meal hydrolysate–chromium complex as a high exhaust chrome tanning agent––pilot scale studies

Acid hydrolysis of horn meal (obtained from raw horns of slaughtered cattle and buffaloes) yields a mixture of water soluble and low molecular weight peptides with average particle size of 3,838 nm (3.84 μm) and mean intensity of 5,243.7 nm (5.24 μm) and mean volume of 6,228.1 nm (6.23 μm). These peptides on reaction with Cr(III) yield a product that exhibits high exhaustion of chromium bath (above 92%) during tanning of hides and skins. To consolidate the results, the process was up-scaled in Central Leather Research Institute (CLRI) pilot plant for commercial trials. This material is applied directly to the pickled pelts at 8% w/w level and then the pelt is converted to wet blues and crust leathers. Control leathers were also processed concurrently using standard chrome tanning salts (8% w/w). Leathers showed the desired level of softness, fullness, shrinkage temperature and physical properties, and are comparable with control ones. Our results have indicated the use of Cr(III)–keratin complex could considerably reduce pollution load of Cr salts in leather processing.     

指数形变幅杆快速设计与谐振特性实验分析

针对超声变幅杆种类多且各项参数计算较复杂和繁琐的问题,运用VB与MATLAB两种软件工具相结合的手段开发了指数形变幅杆参数计算软件;并以SolidWorks为平台,利用VB调用SolidWorks的API函数通过参数驱动实现指数形变幅杆在SolidWorks中自动生成三维模型,从而完成指数形超声变幅杆的快速设计。设计加工了大、中、小截面指数形变幅杆,通过对有限元模态分析结果和锤击法模态实验结果的对比分析,从而验证了设计方法的准确性,为超声变幅杆快速系列化设计提供了参考。     

OPTIMAL MODEL OF COMBINED PHASE CENTER FOR HORN FEEDS AND ITS COMPUTATIONAL METHOD

A definition of combined phase center for horn feeds is given.Formulas of E-planeand H-plane combined phase center for conical horns and the corresponding Optimal model arepresented,and a fast optimization method for solving this model is described.By using thismethod,the phase center of corrugated horn is discussed and calculated,and the variation of thephase center with distance and operating frequency is given.     

Theory revision with queries: Horn, read-once, and parity formulas

A theory, in this context, is a Boolean formula; it is used to classify instances, or truth assignments. Theories can model real-world phenomena, and can do so more or less correctly. The theory revision, or concept revision, problem is to correct a given, roughly correct concept. This problem is considered here in the model of learning with equivalence and membership queries. A revision algorithm is considered efficient if the number of queries it makes is polynomial in the revision distance between the initial theory and the target theory, and polylogarithmic in the number of variables and the size of the initial theory. The revision distance is the minimal number of syntactic revision operations, such as the deletion or addition of literals, needed to obtain the target theory from the initial theory. Efficient revision algorithms are given for Horn formulas and read-once formulas, where revision operators are restricted to deletions of variables or clauses, and for parity formulas, where revision operators include both deletions and additions of variables. We also show that the query complexity of the read-once revision algorithm is near-optimal.     

Recognition of Simple Enlarged Horn Formulas and Simple Extended Horn Formulas

The enlarged Horn formulas generalize the extended Horn formulas introduced by Chandru and Hooker (1991). Their satisfying truth assignments can be generated with polynomial delay. Unfortunately no polynomial algorithm is known for recognizing enlarged Horn formulas or extended Horn formulas. In this paper we define the class of simple enlarged Horn formulas, a subclass of the enlarged Horn formulas, that contains the simple extended Horn formulas introduced by Swaminathan and Wagner (1995). We present recognition algorithms for the simple enlarged Horn formulas and the simple extended Horn formulas whose complexity is bounded by the complexity of the arborescence-realization problem.     

An efficient algorithm for Horn description

We give a new algorithm for computing a prepositional Horn CNF formula given the set of its models. Its running time is O(|R|n(|R|+n)), where |R| is the number of models and n that of variables, and the computed CNF contains at most |R|n clauses. This algorithm also uses the well-known closure property of Horn relations in a new manner.     

Correlations between Horn fractions, satisfiability and solver performance for fixed density random 3-CNF instances

An enhanced concept of sub-optimal reverse Horn fraction of a CNF-formula was introduced in [18]. It was shown that this fraction is very useful in effectively (almost) separating 3-colorable random graphs with fixed node-edge density from the non-3-colorable ones. A correlation between this enhanced sub-optimal reverse Horn fraction and satisfiability of random 3-SAT instances with a fixed density was observed. In this paper, we present experimental evidence that this correlation scales to larger-sized instances and that it extends to solver performances as well, both of complete and incomplete solvers. Furthermore, we give a motivation for various phases in the algorithm aHS, establishing the enhanced sub-optimal reverse Horn fraction, and we present clear evidence for the fact that the observed correlations are stronger than correlations between satisfiability and sub-optimal MAXSAT-fractions established similarly to the enhanced sub-optimal reverse Horn fraction. The latter observation is noteworthy because the correlation between satisfiability and the optimal MAXSAT-fraction is obviously 100%. AMS subject classification 90C05, 03B99, 68Q01, 68W01     

An algorithm to compute maximal contractions for Horn clauses

In the theory of belief revision, the computation of all maximal subsets (maximal contractions) of a formula set with respect to a set of facts is one of the key problems. In this paper, we try to solve this problem by studying the algorithm to compute all maximal contractions for Horn clauses. First, we point out and prove the conversion relationship between minimal inconsistent subsets of union of the formula set and the set of facts and maximal contractions of the formula set with respect to th...