Neighborhood Portfolio Approach for Local Search Applied to Timetabling Problems

A recent trend in local search concerns the exploitation of several different neighborhoods so as to increase the ability of the algorithm to navigate the search space. In this work we investigate a hybridization technique, that we call Neighborhood Portfolio Approach, that consists in the interleave of local search techniques based on various combinations of neighborhoods. In particular, we are able to select the most effective search technique through a systematic analysis of all meaningful combinations built upon a set of basic neighborhoods. The proposed approach is applied to two practical problems belonging to the timetabling family, and systematically tested and compared on real-world instances. The experimental analysis shows that our approach leads to automatic design of new algorithms that provide better results than basic local search techniques.     

Properties of Tense Logics

Based on the results of [11] this paper delivers uniform algorithms for deciding whether a finitely axiomatizable tense logic

• has the finite model property,
• is complete with respect to Kripke semantics,
• is strongly complete with respect to Kripke semantics,
• is d-persistent,
• is r-persistent.

It is also proved that a tense logic is strongly complete iff the corresponding variety of bimodal algebras is complex, and that a tense logic is d-persistent iff it is complete and its Kripke frames form a first order definable class. From this we obtain many natural non-d-persistent tense logics whose corresponding varieties of bimodal algebras are complex. Mathematics Subject Classification: 03B45, 03B25.     

Pyrene-appended calix[4]crowned logic gates involving normal and reverse PET: NOR, XNOR and INHIBIT

As a novel sensing system, N-(1-pyrenylmethyl) amide-appended calix[4]crown-5 (2) and crown-6 (3) have been newly synthesized. Judging from the fluorescence changes upon the addition of cations, 3 having crown-6 ring showed the Pb²⁺ ion selectivity over other cations tested regarding fluorescence quenching. Upon the Pb²⁺ ion coordination to two amide oxygen atoms with aid of crown ring, a reverse-photo-induced electron transfer (PET) occurs in such a way that electrons transfer from the pyrene groups to the electron deficient amide oxygen atoms to give a quenched fluorescence. By the addition of either HClO₄ or triethylamine in the solution of 3, the fluorescence intensity decreased because of the reverse-PET from pyrene groups to protonated amide oxygen atoms and because of normal PET from the nitrogen anion formed by triethylamine to pyrene groups, respectively. For 3, NOR logic gate in which the strong fluorescence signal appears at 395 nm (output: 1) is operated only when neither of triethylamine nor Pb(ClO₄)₂ (inputs A and B) is added (A=B: 0). XNOR gate is also operated only when both of two inputs are added (triethylamine and HClO₄, A=B: 1) or when neither of two inputs is added (A=B: 0). Then, for 3, new INHIBIT gate system was also designed using such combinational inputs as HClO₄, Pb(ClO₄)₂ and triethylamine.     

On relaxed greedy randomized Kaczmarz methods for solving large sparse linear systems

For solving large sparse systems of linear equations by iteration methods, we further generalize the greedy randomized Kaczmarz method by introducing a relaxation parameter in the involved probability criterion, obtaining a class of relaxed greedy randomized Kaczmarz methods. We prove the convergence of these methods when the linear system is consistent, and show that these methods can be more efficient than the greedy randomized Kaczmarz method if the relaxation parameter is chosen appropriately.     

苦参碱和槐定碱在多刺激响应性水凝胶薄膜电极上的可调控电化学行为及其逻辑门构建

采用苦参碱(Matrine, MT)和槐定碱(Sophoridine, SR)作为电活性药物分子探针, 考察了聚(N-异丙基)丙烯酰胺(PNIPAM)水凝胶薄膜的刺激响应特性; 并通过循环伏安(CV)法和扫描电子显微镜(SEM)研究了PNIPAM在不同外界刺激条件(如温度、 盐浓度和甲醇)下结构的改变. 在25 ℃时, 药物分子MT和SR在玻碳电极上产生较大的氧化峰电流, 随着温度升高至40 ℃, 药物分子探针的氧化峰电流逐渐减小. 考察了不同Na₂SO₄浓度和不同比例甲醇对PNIPAM水凝胶薄膜的影响, 发现MT和SR的氧化峰电流随着Na₂SO₄浓度(00.45 mol/L)和甲醇比例(040%)的升高而减小. 结果表明, MT和SR可作为分子探针研究PNIPAM水凝胶薄膜对环境的三重刺激响应性开关行为, 并可进一步构筑3-输入/2-输出的逻辑门系统.     

Randomized Runge–Kutta method — Stability and convergence under inexact information

We deal with optimal approximation of solutions of ODEs under local Lipschitz condition and inexact discrete information about the right-hand side functions. We show that the randomized two-stage Runge–Kutta scheme is the optimal method among all randomized algorithms based on standard noisy information. We perform numerical experiments that confirm our theoretical findings. Moreover, for the optimal algorithm we rigorously investigate properties of regions of absolute stability.     

周期性极化铌酸锂晶体的电光复合逻辑门

根据准相位匹配线性电光效应耦合波理论,基于单个周期性极化铌酸锂晶体,提出了外电场可控的电光复合与门、或门的逻辑计算方法.采用级联周期性极化铌酸锂晶体,探讨了外电场可控的电光复合逻辑异或门、半加法器、半减法器的逻辑计算方法.在外加电场分别为0.184KV/mm和0.368KV/mm条件下,分析了光波的波长、方位角和极角、晶体的温度对逻辑输出的影响.研究结果表明,基本逻辑门的逻辑计算能够成功实现,但其逻辑计算对光波波长、晶体温度、方位角和极化角非常敏感,这些参量轻微的变化会导致逻辑输出的改变.该方案可推广到更为复杂的基本逻辑门以及三个以上逻辑输入与输出的基本逻辑门中.     

Superconducting gates with fluxon logics

We have developed several logic gates (OR, XOR, AND and NAND) made of superconducting Josephson junctions. The gates based of the flux cloning phenomenon and high speed of fluxons moving in Josephson junctions of different shapes. In a contrast with previous design the gates operates extremely fast since fluxons are moving with the speed close to the speed of light. We have demonstrated their operations and indicated several ways to made a more complicated logic elements which have at the same time a compact form.     

An improved randomized approximation algorithm for maximum triangle packing

This paper deals with the maximum triangle packing problem. For this problem, Hassin and Rubinstein gave a randomized polynomial-time approximation algorithm that achieves an expected ratio of for any constant ?>0. By modifying their algorithm, we obtain a new randomized polynomial-time approximation algorithm for the problem which achieves an expected ratio of 0.5257(1−?) for any constant ?>0.