Dalian University of Technology

About: Dalian University of Technology is a education organization based out in Dalian, China. It is known for research contribution in the topics: Catalysis & Finite element method. The organization has 60890 authors who have published 71921 publications receiving 1188356 citations. The organization is also known as: Dàlián Lǐgōng Dàxué.

Electrodeposition of high-capacitance 3D CoS/graphene nanosheets on nickel foam for high-performance aqueous asymmetric supercapacitors

Abstract: Electrochemical energy storage devices that encompass the capability of offering both excellent capacitance and rate performance have always be in high demand. Herein, we present a simple and green two-step electrodeposition process to fabricate a high-performance 3D CoS/graphene hybrid network with a nanosheet structure on Ni foam. The nanosheet-like CoS is tightly wrapped and anchored by the graphene layer and the two different material species are nicely integrated together, leading to increased conductivity and enlarged electroactive surface area of the electrode materials. The CoS/graphene composites exhibit an impressive specific capacitance of 3785 F g−1 at a current density of 1 A g−1, a favorable rate capability with 82% retention at 20 A g−1. A CoS/graphene‖activated carbon asymmetric supercapacitor fabricated in 2 M KOH solution exhibits a maximum energy density of 29 Wh kg−1 at the power density of 800 W kg−1, and a power density of 40.0 kW kg−1 (at the energy density of 11.0 Wh kg−1). Furthermore, 70% capacitance retention was obtained after 10 000 cycles within the potential window of 0–1.6 V. The excellent performance of the CoS/graphene composites demonstrated in this work has revealed the promising potential of adopting the CoS/graphene hybrid network for high performance supercapacitors.

Quantum discord of two-qubit X states

Abstract: Quantum discord provides a measure for quantifying quantum correlations beyond entanglement and is very hard to compute even for two-qubit states because of the minimization over all possible measurements. Recently a simple algorithm to evaluate the quantum discord for two-qubit $X$ states was proposed by Ali, Rau, and Alber [Phys. Rev. A 81, 042105 (2010)] with minimization taken over only a few cases. Here we shall at first identify a class of $X$ states, whose quantum discord can be evaluated analytically without any minimization, for which their algorithm is valid, and also identify a family of $X$ states for which their algorithm fails. And then we demonstrate that this special family of $X$ states provides furthermore an explicit example for the inequivalence between the minimization over positive operator-valued measures and that over von Neumann measurements.

Athermal Silicon-on-insulator ring resonators by overlaying a polymer cladding on narrowed waveguides

Abstract: Athermal silicon ring resonators are experimentally demonstrated by overlaying a polymer cladding on narrowed silicon wires. The ideal width to achieve athermal condition for the TE mode of 220 nm-height SOI waveguides is found to be around 350 nm. After overlaying a polymer layer, the wavelength temperature dependence of the silicon ring resonator is reduced to less than 5 pm/degrees C, almost eleven times less than that of normal silicon waveguides. The optical loss of a 350-nm bent waveguide (with a radius of 15 microm) is extracted from the ring transmission spectrum. The scattering loss is reduced to an acceptable level of about 50 dB/cm after overlaying a polymer cladding.

Managing Multigranular Linguistic Distribution Assessments in Large-Scale Multiattribute Group Decision Making

Abstract: Linguistic large-scale group decision making (LGDM) problems are more and more common nowadays. In such problems a large group of decision makers are involved in the decision process and elicit linguistic information that are usually assessed in different linguistic scales with diverse granularity because of decision makers’ distinct knowledge and background. To keep maximum information in initial stages of the linguistic LGDM problems, the use of multigranular linguistic distribution assessments seems a suitable choice, however, to manage such multigranular linguistic distribution assessments, it is necessary the development of a new linguistic computational approach. In this paper, it is proposed a novel computational model based on the use of extended linguistic hierarchies, which not only can be used to operate with multigranular linguistic distribution assessments but also can provide interpretable linguistic results to decision makers. Based on this new linguistic computational model, an approach to linguistic large-scale multiattribute group decision making is proposed and applied to a talent selection process in universities.

Bimetallic Pd–Cu catalysts for selective CO2 hydrogenation to methanol

Abstract: This paper reports on novel Pd–Cu bimetallic catalysts for selective CO2 hydrogenation to methanol. Strong synergistic effect on promoting methanol formation was observed over amorphous silica supported Pd–Cu bimetallic catalysts when the Pd/(Pd + Cu) atomic ratios lied in the range of 0.25–0.34. The methanol formation rate over Pd(0.25)–Cu/SiO2 was two times higher than the simple sum of those over monometallic Cu and Pd catalysts. The Pd–Cu bimetallic catalysts were characterized by X-ray diffraction, transmission electron microscopy, scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed desorption. Detailed characterization results demonstrated the importance of two well-dispersed Pd–Cu alloy particles (PdCu and PdCu3) for the observed methanol promotion over Pd–Cu bimetallic catalysts. Similar bimetallic promotion was also observed for Pd–Cu catalysts supported on uniform mesoporous MCM-41, SBA-15 and MSU-F. Conversion-selectivity profile of the Pd–Cu/SiO2 catalyst suggested that CO2 was a primary carbon source for methanol synthesis at lower CO2 conversion, and byproduct CO contributed at higher CO2 conversion within the conversion range examined.