Numerical simulation of temperature field of a new type of freezing device under seepage effect.

In order to investigate the development of the temperature field of a new type of freezing reinforcement under seepage conditions, in this paper, COMSOL finite element software was used to simplify the model and simulate the effect of groundwater seepage on the development of the temperature field of frozen pipes by coupling the Darcy's law module and the heat transfer module for porous media. The heads of water were also varied to simulate the change in seepage velocity to further investigate the effect of seepage velocity on the temperature field. The results of the study show that the freezing wall formed in the high head region was thinner than that in the low head region due to the effect of seepage, and this phenomenon was aggravated with the increase of seepage rate; The effect of seepage action on the temperature field had a hysteresis along the seepage direction; When the seepage rate was greater than 1.

Access to Polysulfides through Photocatalyzed Dithiosulfonylation.

In this study, we outline a general method for photocatalyzed difunctionalization of alkenes, a diene, alkynes, 1,3-enynes, and [1.1.1]propellane using dithiosulfonate reagents (ArSO -SSR) with improved atom economy.

Convergent Synthesis of 1,4-Dicarbonyl -Alkenes through Three-Component Coupling of Alkynes, α-Diazo Sulfonium Triflate, and Water.

We report a general protocol for the convergent synthesis of 1,4-dicarbonyl -alkenes form alkynes using α-diazo sulfonium triflate and water. The C═O, C═C, and C-H bonds are formed under mild conditions with a wide range of functional groups tolerated. The reaction exhibits excellent -selectivity and complete regioselectivity.

Dithiolato- and halogenido-bridged nickel-iron complexes related to the active site of [NiFe]-Hases: preparation, structures, and electrocatalytic H production.

A new series of the structural and functional models for the active site of [NiFe]-Hases has been prepared by a simple and convenient synthetic route. Thus, treatment of diphosphines RN(PPh) (1a, R = p-MeCHCH; 1b, R = EtOCCH) with an equimolar NiCl·6HO, NiBr·3HO, and NiI in refluxing CHCl/MeOH or EtOH gave the mononuclear Ni complexes RN(PPh)NiX (2a, R = p-MeCHCH, X = Cl; 2b, R = EtOCCH, X = Cl; 3a, R = p-MeCHCH, X = Br; 3b, R = EtOCCH, X = Br; 4a, R = p-MeCHCH, X = I; 4b, R = EtOCCH, X = I) in 67-97% yields. Further treatment of complexes 2a,b-4a,b with an equimolar mononuclear Fe complex (dppv)(CO)Fe(pdt) and NaBF resulted in formation of the targeted model complexes [RN(PPh)Ni(μ-pdt)(μ-X)Fe(CO)(dppv)](BF) (5a, R = p-MeCHCH, X = Cl; 5b, R = EtOCCH, X = Cl; 6a, R = p-MeCHCH, X = Br; 6b, R = EtOCCH, X = Br; 7a, R = p-MeCHCH, X = I; 7b, R = EtOCCH, X = I) in 60-96% yields.

Hydrophilic Quaternary Ammonium-Group-Containing [FeFe]-Hydrogenase Models: Synthesis, Structures, and Electrocatalytic Hydrogen Production.

The first quaternary ammonium-group-containing [FeFe]-hydrogenase models [(μ-PDT)Fe (CO) {κ -(Ph P) N(CH ) NMe BzBr}] (2; PDT=propanedithiolate) and [(μ-PDT)Fe (CO) {μ-(Ph P) N(CH ) NMe BzBr}] (4) have been prepared by the quaternization of their precursors [(μ-PDT)Fe (CO) {κ -(Ph P) N(CH ) NMe }] (1) and [(μ-PDT)Fe (CO) {μ-(Ph P) N(CH ) NMe }] (3) with benzyl bromide in high yields. Although new complexes 1-4 have been fully characterized by spectroscopic and X-ray crystallographic studies, the chelated complexes 1 and 2 converted into their bridged isomers 3 and 4 at higher temperatures, thus demonstrating that these bridged isomers are thermodynamically favorable. An electrochemical study on hydrophilic models 2 and 4 in MeCN and MeCN/H O as solvents indicates that the reduction potentials are shifted to less-negative potentials as the water content increases.

Three axis electronic flight motion simulator real time control system design and implementation.

A three axis electronic flight motion simulator is reported in this paper including the modelling, the controller design as well as the hardware implementation. This flight motion simulator could be used for inertial navigation test and high precision inertial navigation system with good dynamic and static performances. A real time control system is designed, several control system implementation problems were solved including time unification with parallel port interrupt, high speed finding-zero method of rotary inductosyn, zero-crossing management with continuous rotary, etc.

An insight into the transcriptome and proteome of the salivary gland of the stable fly, Stomoxys calcitrans.

Adult stable flies are blood feeders, a nuisance, and mechanical vectors of veterinary diseases. To enable efficient feeding, blood sucking insects have evolved a sophisticated array of salivary compounds to disarm their host's hemostasis and inflammatory reaction. While the sialomes of several blood sucking Nematocera flies have been described, no thorough description has been made so far of any Brachycera, except for a detailed proteome analysis of a tabanid (Xu et al.

Nonlinear control for a class of hydraulic servo system.

The dynamics of hydraulic systems are highly nonlinear and the system may be subjected to non-smooth and discontinuous nonlinearities due to directional change of valve opening, friction, etc. Aside from the nonlinear nature of hydraulic dynamics, hydraulic servo systems also have large extent of model uncertainties. To address these challenging issues, a robust state-feedback controller is designed by employing backstepping design technique such that the system output tracks a given signal arbitrarily well, and all signals in the closed-loop system remain bounded.