管翅式表冷器数值模拟与性能分析

编制了结霜工况下 ,适用于不同空气流态的蒸发器动态仿真程序。根据在低温风洞实验台中不同工况下测得的实验数据对程序进行了修正 ,并将修正后的程序用于对表面式空气冷却器的性能进行分析 ,从而得出了改进设计的方法。     

Well‐Defined Dinuclear Gold Complexes for Preorganization‐Induced Selective Dual Gold Catalysis

The synthesis, reactivity, and potential of well‐defined dinuclear gold complexes as precursors for dual gold catalysis are explored. Using the preorganizing abilities of the ditopic PN^HP^iPr ( L^H ) ligand, dinuclear Au^I–Au^I complex 1 and mixed‐valent Au^I–Au^III complex 2 provide access to structurally characterized chlorido‐bridged cationic species 3 and 4 upon halide abstraction. For 2 , this transformation involves unprecedented two‐electron oxidation of the redox‐active ligand, generating a highly rigidified environment for the Au₂ core. Facile reaction with phenylacetylene affords the σ,π‐activated phenylacetylide complex 5 . When applied in the dual gold heterocycloaddition of a urea‐functionalized alkyne, well‐defined precatalyst 3 provides high regioselectivities for the anti‐Markovnikov product, even at low catalyst loadings, and outperforms common mononuclear Au^I systems. This proof‐of‐concept demonstrates the benefit of preorganization of two gold centers to enforce selective non‐classical σ,π‐activation with bifunctional substrates.     

等深度螺旋槽止推轴承的边界元法计算

本文以分析等深度螺旋槽止推轴承为例,介绍了边界元法在润滑力学研究领域中的应用。以及相应的边界条件的处理方法,并且讨论了轴承尺寸参数对性能参数的影响。     

Solution and Gas‐Phase Acidities of all‐trans (all‐E) Retinoic Acid: An Experimental and Computational Study

Retinoic acid is of fundamental biological importance. Its acidity was determined in the gas phase and in acetonitrile solution by means of mass spectrometry and UV/Vis spectrophotometry, respectively. The intrinsic acidity is slightly higher than that of benzoic acid. In solution, the situation is opposite. The experimental systems were described theoretically applying quantum chemical methods (wave function theory and density functional theory). This allowed the determination of the molecular structure of the acid and its conjugate base, both in vacuo and in solution, and for computational estimates of its acidity in both phases.     

The flowfield characteristics of a precombustion chamber of coflowing jets with large velocity differences

A new type of precombustion chamber has been developed in which coflowing jets with large velocity differences are used. A finite difference calculation procedure based on the SIMPLE algorithm is developed for the numerical simulation of this flowfield. This paper presents a statement of the algorithm, boundary condition specifications, and the results of computational experiments. The computational results demonstrate the existence of the large recirculation regions. It displays significant three-dimensional characteristics. The effects of design parameters on the recirculation features are discussed briefly in the present study.     

STABILITY STUDY OF AN UNSTEADY OSCILLATION FLOW

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Improved Pöschl–Teller potential energy model for diatomic molecules

By employing the dissociation energy and the equilibrium internuclear distance for a diatomic molecule as explicit parameters, we construct an improved Pöschl–Teller potential energy model. We analyze the average absolute deviations of the improved Pöschl–Teller and Morse potentials from the experimental Rydberg–Klein–Rees (RKR) potentials for six diatomic molecules. It is found that the improved Pöschl–Teller potential is more accurate than the Morse potential in fitting experimental RKR potential curves over a large range of internuclear distances for six molecules examined.     

Diketopyrrolopyrrole-based conjugated polymers as additives to optimize morphology for polymer solar cells

Novel random copolymers for optimizing the morphology of the active layer for high performance organic photovoltaic devices have been demonstrated. Three ternary random copolymers PTBDTDPPSi CN(3/7), PTBDTDPPSi CN(5/5), PTBDTDPPSi CN(7/3) were prepared by polymerization of electron-donating thienyl-substituted benzodithiophene(TBDT) with 2,5-bis[8-(1,1,3,3,5,5,5-heptamethyltrisiloxane-3-yl)octly]-pyrrolo[3,4-c]pyrrole-1,4-dione(DPPSi) and 2,5-dio[5-(5-cyano-5,5-dimethyl-pentyl)]-3,6-dithiophen-2-yl-pyrrolo[3,4-c]pyrrole-1,4-dione(DPPCN) of different ratios. The DPPCN block can well-tune the light absorption and molecular packing, while the DPPSi block is in favor of enhancing the charge mobility. And the formation of organic Si―O―Si networks is beneficial to stabilize the morphology of the active layer. These new copolymers have narrow bandgaps and broaden visible light absorption from 500 nm to 1000 nm. Careful balance of the contents of the trimethoxysilyl group and the cyano group can well-tune the surface energy and morphology of the copolymers. Incorporation of these novel copolymers as additives into the blend of poly(3-hexylthiophene)(P3HT) and [6,6]-phenyl-C60-butyric acid methyl ester(PC_(61)BM) is found to effectively broaden the light absorption, improve the compatibility and morphology of the active layer. As a result, some devices with certain ratios of these copolymers as additives achieve the enhanced efficiency compared with the device based on pristine P3HT:PC_(61)BM.     

大速差预燃室的流场特征

一种新型的大速差同向射流预燃室已经研制成功。本文基于SIMPLE算法,发展了计算这种流场的数值解法。文中介绍了算法、边界条件的详细说明以及计算结果。计算结果证明存在大面积迴流区;呈现了重要的三维特征。本文初步讨论了设计参数对迴流特性的影响。     

CH Activation of Benzene by a Photoactivated NiII(azide): Formation of a Transient Nickel Nitrido Complex

Photochemical activation of nickel‐azido complex 2 [Ni(N₃)(PNP)] (PN^HP=2,2′‐di(isopropylphosphino)‐4,4′‐ditolylamine) in neat benzene produces diamagnetic complex 3 [Ni(Ph)(PN^PN^H)], which is crystallographically characterized. DFT calculations support photoinitiated N₂‐loss of the azido complex to generate a rare, transient Ni^IV nitrido species, which bears significant nitridyl radical character. Subsequent trapping of this nitrido through insertion into the Ni? P bond generates a coordinatively unsaturated Ni^II imidophosphorane P?N donor. This species shows unprecedented reactivity toward 1,2‐addition of a C? H bond of benzene to form 3 . The structurally characterized chlorido complex 4 [Ni(Cl)(PN^PN^H)] is generated by reaction of 3 with HCl or by direct photolysis of 2 in chlorobenzene. This is the first report of aromatic C? H bond activation by a trapped transient nitrido species of a late transition metal.