共查询到19条相似文献，搜索用时 187 毫秒
1.
布尔可满足性（简称SAT）问题是研究最广泛的NP-完全（简称NPC）问题之一。编码、预处理和求解算法是SAT问题求解的3个关键技术,近年来涌现了大量成果。SAT问题广泛应用在生产和生活中, SAT求解技术的健壮性和综合性能迫切需要进一步提升。从SAT问题分类、SAT问题应用领域、研究现状及面临的挑战等方面对相关研究成果进行梳理。 相似文献
2.
为减少在公链上基于哈希的工作量证明中无意义计算消耗,合理利用区块链网络算力,创建一个促进可满足性问题（SAT）研究的有用工作社区环境,基于 SAT 问题求解,开发一种有用工作量证明共识机制,通过竞争解决困难 SAT 问题的方法获得区块链中区块构造权,并使各节点间达成共识。实验证明,基于该共识算法的区块链系统性能稳定,且各算法在系统中运行平稳,基于 SAT 求解的工作量证明共识机制有助于解决基于哈希计算工作量证明的无意义消耗问题,更好创造 SAT 问题的研究环境。 相似文献
3.
SAT问题(可满足性问题)是理论计算机科学的核心问题,研究SAT问题的方法很多,利用极小不可满足公式的性质来研究SAT问题是近几年的一个热点研究方向.文章主要利用(1,*)-消解和分裂方法研究了差为2的极大极小不可满足公式集(MAX-MU(2))的结构和复杂度. 相似文献
4.
SAT问题（可满足性问题）是计算机科学的核心问题，研究SAT问题的方法很多，利用极小不可满足公式的性质来研究SAT问题是近几年兴起的一个热点研究方向．文章主要利用（1，＊）-消解和分裂方法研究了差为2的唯一极小不可满足公式集（Unique-MU（2））和差为2的对称极小不可满足公式集（SYM-MU（2））的结构和复杂度． 相似文献
5.
SAT问题(可满足性问题)是计算机科学的核心问题,研究SAT问题的方法很多,利用极小不可满足公式的性质来研究SAT问题是近几年兴起的一个热点研究方向. 本文主要利用1(,)*-消解和分裂方法研究了差为2的碰撞极小不可满足公式集()2(MUHIT-)的结构和复杂度.此前,只有G.Davydov, I.Davydova 和H.Kleine Büning对)1(MU和)2(MU的结构和复杂度得出了较好的结果. 相似文献
6.
SAT问题(可满足性问题)是计算机科学的核心问题,研究问题的方法很多,利用极小不可满足公式的性质来研究SAT问题是近几年兴起的一个热点研究方向. 文章主要利用,(1,*)-消解和分裂方法研究了差为2的唯一极小不可满足公式集(Unique-MU(2))和差为2的对称极小不可满足公式集(SYM-MU(2))的结构和复杂度. 相似文献
7.
针对CAE仿真技术中偏微分方程数值模型求解的稳定性、准确性以及步长参数设置问题,采用CAE技术中常用的一阶迎风格式、Lax-Wendroff格式以及隐式中心格式分别对双曲偏微分方程数值模型进行计算分析.结果表明:Lax-Wendroff格式具有较高的求解精度,而隐式中心格式属于无条件稳定,其求解易于收敛;在满足差分计算稳定性的条件下,随着时间步长τ的减小,差分数值解的结果误差逐渐降低,但是其求解精度主要依赖合适的差分格式. 相似文献
8.
求解非定常对流扩散方程的高精度差分格式 总被引：1，自引：0，他引：1
杨绍华 《商丘师范学院学报》2009,25(3)
提出了一种新的数值求解一维非定常对流扩散方程高精度差分格式.利用Fourier分析方法证明了该格式是无条件稳定的,而且适合于大梯度(高雷诺数)问题的数值求解.数值实验结果证明了本文的精确性、稳定性和对高网络雷诺数问题的强适应性. 相似文献
9.
徐小萍 《廊坊师范学院学报(自然科学版)》2011,11(5):14-15
在极小不可满足公式和可满足公式的基础上给出极小不可满足核的定义,并给出用布尔可满足求解器提取不可满足公式的极小不可满足核的方法。 相似文献
10.
11.
Daniel M. Bolt 《Journal of Educational Measurement》2000,37(4):307-327
This paper considers a modification of the DIF procedure SIBTEST for investigating the causes of differential item functioning (DIF). One way in which factors believed to be responsible for DIF can be investigated is by systematically manipulating them across multiple versions of an item using a randomized DIF study (Schmitt, Holland, & Dorans, 1993). In this paper: it is shown that the additivity of the index used for testing DIF in SIBTEST motivates a new extension of the method for statistically testing the effects of DIF factors. Because an important consideration is whether or not a studied DIF factor is consistent in its effects across items, a methodology for testing item x factor interactions is also presented. Using data from the mathematical sections of the Scholastic Assessment Test (SAT), the effects of two potential DIF factors—item format (multiple-choice versus open-ended) and problem type (abstract versus concrete)—are investigated for gender Results suggest a small but statistically significant and consistent effect of item format (favoring males for multiple-choice items) across items, and a larger but less consistent effect due to problem type. 相似文献
12.
浅谈PBL中问题的设置 总被引：20，自引：0，他引：20
基于问题的学习是建构主义理论指导下的以学生为中心的一种教学模式。在该模式中,问题是PBL能否成功实施的关键。本文论述了PBL中问题开发的程序和步骤。 相似文献
13.
This article examines the influence of keyboarding versus handwriting in a high-stakes writing assessment. Conclusions are based on data collected from a pilot project to move Old Dominion University's Exit Exam of Writing Proficiency from a handwritten format into a dual-option format (i.e., the students may choose to handwrite or keyboard the exam). This test case is used to demonstrate the complex implications for a writing assessment tool when universities aim to accommodate students’ various methods of physically creating a text. Discussion includes speculation about the format of the writing component on the SAT. It is argued that by analyzing the differences in high-stakes exams when students keyboard and when they handwrite, researchers can better understand how the material conditions for composing influence students and raters. It is concluded that if handwriting and keyboarding represent even slightly different composing skills and cognitive processes, then high-stakes writing assessments should aim to accommodate students by providing methods of textual production with which students are most comfortable, even as this accommodation produces new challenges for the creators and managers of large-scale writing assessments. 相似文献
14.
调整管作为LDO线性稳压器的输出功率管是非常关键的模块,本文从LPNP和VPNP的版图和等效电路模型出发分析这两者的电流放大倍数β、集电极最大允许工作电流ICM和饱和压降VCE（SAT）,并给出HSPICE的仿真结果,以此来把握LDO调整管模块的设计． 相似文献
15.
Nancy Burton 《Educational Measurement》1996,15(4):5-9
How has the SAT changed in content and format? Why was it changed? How have changes to the mathematics test affected men's and women's performance? 相似文献
16.
Implicit theories of intelligence play an important role in students’ academic motivation and achievement. This longitudinal study examined how the trajectories of implicit theories of intelligence from Grade 8 to Grade 10 were related to Grade 12 SAT achievement via Grade 11 achievement goals. We employed parallel process models to examine changing patterns of Korean students’ (N = 6491) entity and incremental theories over three years. Results showed that both entity and incremental theories increased over time. The intercept and the slope of entity theory were negatively related with the intercept and the slope of incremental theory, respectively. In line with Dweck’s theoretical framework, increases in incremental theory were found to predict SAT achievement via mastery-approach goals, whereas increases in entity theory predicted SAT achievement via performance-approach goals. The results indicate that different types of achievement goals play unique roles in mediating the relation between changes in implicit theories and SAT achievement. 相似文献
17.
Diagrams and illustrations as aids to problem solving 总被引：1，自引：0，他引：1
K. P. Szlichcinski 《Instructional Science》1979,8(3):253-274
The psychological literature relating to factors which should be taken into account in the design of illustrations and pictorial instructions as aids to problem solving is reviewed. The problem solver can invoke a wide range of strategies for using pictorial materials to achieve his goal, although pictorial instructions which indicate how to perform actions place a tighter constraint on the choice of strategy than illustrations showing only states to be attained. The designer must make his graphics compatible with as wide a range of strategies for using them as possible while building on the knowledge the problem solver already possesses.The author now works for the Post Office Telecommunications Systems Strategy Department, 88 Hills Road, Cambridge. 相似文献
18.
王金萍 《天津职业院校联合学报》2004,6(2):29-30
电子电路课程是电专业和非电专业的一门非常重要的技术基础课程。要根据课程的教学现状、教学中存在的问题进行探讨,结合课程教学与实验提高学生电路分析与设计能力。 相似文献
19.
This paper presents an efficient method for globally optimizing and automating component sizing for rotary traveling wave oscillator arrays. The lumped equivalent model of transmission lines loaded by inverter pairs is evaluated and posynomial functions for oscillation frequency, power dissipation, phase noise, etc. are formulated using transmission line theory. The re- sulting design problem can be posed as a geometric programJning problem, which can be efficiently solved with a convex opti- mization solver. The proposed method can compute the global optima more efficiently than the traditional iterative scheme and various design problems can be solved with the same circuit model. The globally optimal trade-off curves between competing objectives are also computed to carry out robust designs and quickly explore the design space. 相似文献