38 research outputs found
There aren't Non-Standard Solutions for the Braid Group Representations of the QYBE Associated with 10-D Representations of SU(4)
It is well known that the quantum Yang-Baxter equations (QYBE) play an important role in various theoretical and mathematical physics, such as completely integrable system in (1 + 1)-dimensions, exactly solvable models in statistical mechanics, the quantum inverse scattering method and the conformal field theories in 2-dimensions. Recently, much remarkable progress has been made in constructing the solutions of the QYBE associated with the representations of lie algebras. It is shown that for some cases except the standard solutions, there also exist new solutions, but the others have not non-standard solutions. In this paper by employing the weight conservation and the diagrammatic techniques we show that the solution associated with the 10-D representations of SU (4) are standard alone
Solutions of the Quantum Yang-Baxter Equations Associated with (1-3/2)-D Representations of SU(sub q) (2)
The solutions of the spectral independent QYBE associated with (1-3/2)-D representations of SU(sub q) (2) are derived, based on the weight conservation and extended Kauffman diagrammatic technique. It is found that there are nonstandard solutions
Robust Adaptive Control and L
This paper deals with the robust stabilizability and L2 disturbance attenuation for a class of time-delay Hamiltonian control systems with uncertainties and external disturbances. Firstly, the robust stability of the given systems is studied, and delay-dependent criteria are established based on the dissipative structural properties of the Hamiltonian systems and the Lyapunov-Krasovskii (L-K) functional approach. Secondly, the problem of L2 disturbance attenuation is considered for the Hamiltonian systems subject to external disturbances. An adaptive control law is designed corresponding to the time-varying delay pattern involved in the systems. It is shown that the closed-loop systems under the feedback control law can guarantee the γ-dissipative inequalities be satisfied. Finally, two numerical examples are provided to illustrate the theoretical developments
Iridium-Catalyzed Intermolecular Azide-Alkyne Cycloaddition of Internal Thioalkynes under Mild Conditions
An iridium-catalyzed azide-alkyne cycloaddition reaction (IrAAC) of electron-rich internal alkynes is described. It is the first efficient intermolecular AAC of internal thioalkynes. The reaction exhibits remarkable features, such as high efficiency and regioselectivity, mild reaction conditions, easy operation, and excellent compatibility with air and a broad spectrum of organic and aqueous solvents. It complements the well-known CuAAC and RuAAC click reactions
Theoretical Studies on the Regioselectivity of Iridium-Catalyzed 1,3-Dipolar Azide-Alkyne Cycloaddition Reactions
Iridium-catalyzed cycloaddition of thioalkynes and bromoalkynes with azides have been investigated with the aid of density functional theory (DFT) calculations at the M06 level of theory. Our investigation focused on the different regioselectivity observed for the reactions of the two classes of alkynes. The DFT results have shown that the mechanisms of cycloaddition reactions using thioalkynes and bromoalkynes as substrates are similar yet different. The reactions of thioalkynes occur via a metallabicyclic Ircarbene intermediate formed through alkyneazide oxidative coupling via attack of the azide terminal nitrogen toward the beta alkyne carbon, whose carbene ligand is stabilized by an alkylthio/arylthio substituent. Reductive elimination from the intermediate leads to the formation of the experimentally observed 5-sulfenyltriazole. In the reactions of bromoalkynes RC=CBr, the reaction mechanism involves the initial formation of a six-membered-ring metallacycle intermediate in the oxidative coupling step. The six-membered-ring intermediate then undergoes isomerization via migrating the terminal azide nitrogen from the beta carbon to the a carbon to form a much less stable metallabicyclic Ircarbene species from which reductive elimination gives 4-bromotriazole
Multi-surrogate multi-tasking optimization of expensive problems
Liao P, Sun C, Zhang G, Jin Y. Multi-surrogate multi-tasking optimization of expensive problems. Knowledge-Based Systems. 2020;205: 106262.Multiple surrogates can be trained in surrogate-assisted optimization of expensive problems to describe different characteristics of the real fitness landscape. It has been shown that optimization assisted by multiple surrogate models are beneficial compared to a single surrogate. Along this line of research, we propose to train two surrogate models, one global surrogate model trained using all available data, and the other one local surrogate model trained using only part of the data subsequently selected from the data sorted according to an ascending order of the objective value. Different from most existing multi-surrogate based approaches, however, we adopt the multi-tasking optimization framework to accelerate the convergence by regarding the two surrogates as two related tasks. This way, two optimal solutions found by the multi-tasking algorithm will be evaluated using the real expensive objective function, and consequently, both the global and local models will be updated. This process repeats until the allowed computational budget is exhausted. Experiments are conducted on twelve widely used benchmark problems of up to 200 dimensions to examine the performance of the proposed algorithm. Our results show that the proposed method is very competitive, has quick convergence and scales well with the increase in the number of decision variables for solving computationally expensive single-objective optimization problems
Non-dominated sorting on performance indicators for evolutionary many-objective optimization
Wang H, Sun C, Zhang G, Fieldsend JE, Jin Y. Non-dominated sorting on performance indicators for evolutionary many-objective optimization. Information Sciences. 2021;551:23-38.Much attention has been paid to evolutionary multi-objective optimization approaches to efficiently solve real-world engineering problems with multiple conflicting objectives. However, the loss of selection pressure and the non-uniformity in the distribution of the Pareto optimal solutions in the objective space can impede both dominance-based and decomposition-based multi-objective optimizers when solving many-objective problems. In this work, we circumvent this issue by exploiting two performance indicators, and use these in an optimizer’s environmental selection via non-dominated sorting. This effectively converts the original many-objective problem into a bi-objective one. Our convergence performance criterion tries to balance the performance of individuals in different parts of the objective space. The angle between solutions on objective space is adopted to measure the diversity of each individual. Using these solutions can be separated into different layers easily, which is often not possible for the original many-objective optimization representation. The performance of the proposed method is evaluated on the DTLZ benchmark problems with up to 30 objectives, and MaF test suite with 10, 15, 20 and 30 objectives. The experimental results show that our proposed method is competitive compared to six recently proposed algorithms, especially for solving problems with a large number of objectives
The complete mitochondrial genome of Niviventer sacer (Rodentia: Muridae)
Niviventer sacer (Rodentia: Muridae) had been regarded as a subspecies of N. confucianus, i.e. N. c. sacer, and was raised as a distinct species recently by our laboratory. We sequenced the complete mitochondrial genome of N. sacer first and annotated the genome structure. The total length of the genome was 16,308Â base pairs (bp) containing 13 protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), and a control region. We also constructed the phylogenetic tree by maximum-likelihood method and it demonstrated that N. sacer was the sister clade of N. confucianus