Mathematical Model of Steady State Operation in Jet Pipe Electro-Hydraulic Servo Valve

Jet pipe electro-hydraulic servo valve is the heart of feedback control systems,and it is one of the mechatronic components used for precision flow control application.It consists of several precision and ddicate components.The performance of the jet pipe servo valve depends on many parameters.During the developmental stage,it is very difficult to ascertain the function parameters.The steady-state analysis of jet pipe electro-hydraulic servo valve has been made to simulate its fluid characteristics （flowin,flow-out,leakage flow,recovery or load pressure,etc.） by mathematical modeling.Theoretical model was conducted on various affecting parameters on the pressure,the main flow rate of fluid,or leakage flow through the receiver holes.The major parameters studied are jet pipe nozzle diameters,receiver hole diameters,angle between the two centre-lines of receiver hole,nozzle offset,and nozzle stand-of distance.In this paper the research is important to determine and optimize the structural parameters of jet pipe servo valve.Thus,equations of the pressure and flow characteristics are set up and the optimal structural parameters of jet pipe are established.

A unified analysis of a micro-beam,droplet and CNT ring adhered on a substrate:Calculation of variation with movable boundaries

In this study, we developed a general method to analytically tackle a kind of movable boundary problem from the viewpoint of energy variation. Having grouped the adhesion of a micro-beam, droplet and carbon nanotube （CNT） ring on a substrate into one framework, we used the developed line of reasoning to investigate the adhesion behaviors of these systems. Based upon the derived governing equations and transversality conditions, explicit solutions involving the critical parameters and morphologies for the three systems are successfully obtained, and then the parameter analogies and common characteristics of them are thor- oughly investigated. The presented method has been verified via the concept of energy release rate in fracture mechanics. Our analyses provide a new approach for exploring the mechanism of different systems with similarities as well as for understanding the unity of nature. The analysis results may be beneficial for the design of nano-structured materi- als, and hold potential for enhancing their mechanical, chemical, optical and electronic properties.

Formation of Hybrid Ring Structure of Cyanurate/Isocyanurate in the Reaction be-tween 2,4,6-Tris(4-Phenyl-Phenoxy)-1, 3,5-Triazine and Phenyl Glycidyl Ether

Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound which were well known as reaction products of cyanate esters and epoxy resins, compounds with hybrid ring structure of cyanurate/isocyanurate were determined. Gibbs free energies of the compound having hybrid ring structure of cyanurate/isocyanurate with two isocyanurate moiety were found to be lower than that of the compound with cyanurate ring structure through calculations. Calculation data supported the existence of hybrid ring structure of cy-anurate/isocyanurate. It was revealed that isomerization from cyanurate to isocyanurate occurs via hybrid ring structure of cyanurate/isocyanurate in the reaction of aryl cyanurate and epoxy.

Numerical Simulation and Analysis of Gas Flow Field in Serrated Valve Column

A three-dimensional computational fluid dynamics （CFD） model for gas flow through a serrated valve tray was presented. The flow field, as well as the dry-pressure drop of the valve under the full-opening condition was simulated based on the proposed model by using FLUENT 6.0 software. Compared with the values of dry-pressure dro.p in different turbulent models, the.simulated.results using RNG κ-ε model are in reasonable agreement with experimental data, indicating that RNG κ-ε model is suitable in simulating gas flow through the serrated valve tray. Then the CFD model combining RNG κ-ε model was used to study the three-dimensional gas flow through the considered serrated valve tray. The simulated results showed that various eddies existed on the serrated valve tray, and both the eddy and the non-eddy areas were nearly equal. The existence of addendum can decrease the eddy area caused by gas passing through the lateral outlet slots. The size of eddies can be reduced by optimizing the distance between valves.

A Mixed-valent Hexanuclear Cu~Ⅱ-Cu~ⅠComplex with Unusual Tridentate pbi Ligand (pbi = 2-(2-Pyridyl)-benzimidazole)

A mixed-valent hexanuclear complex [Cu^ⅡCu^Ⅰ2（pbi）2Br2]2 （pbi = （2-（2-pyridyl）-benzimidazole） exhibiting a dimeric unit bridged by two Br atoms was synthesized by hydrothermal reaction Interestingly, there exist intramolecular and intermolecular n^zstacking interactions as well as metalaromatic ring interactions in the title complex. The crystal belongs to the monoclinic system, space group P1, with a = 7.1061（9）, b = 12.1008（13）, c = 14.0711（17） A, α=91.742（8）,β=100.155（9）, γ=90.486（7）°, V = 1190.3（2） A^3, Z = 2, C48H32Br4CucoNt2, Mr = 1477.74, Dc= 2.061 g/cm^3, F（000） = 718, μ（MoKα） = 6.039 mm^-1, the final R = 0.0481 and wR = 0.0974 for 3426 observed reflections （I 〉 2σ（I））.

Selective Construction of Borromean Rings and Tweezer-Like Molecular Assembly Featuring Cp^(*)Rh/Ir Clips for Near-Infrared Photothermal Conversion

Making full use of coordination-driven self-assembly strategy,we herein described the selective synthesis of a molecular Borromean rings and two cases of “U”-shaped tweezer-like molecular assemblies in high yield by using bipyridyl ligands based on biphenyl unit and half-sandwich binuclear rhodium(III)/iridium(III) building blocks.The selective synthesis was realized by adjusting the length of dipyridyl arms.The utilization of curved U-shaped bipyridyl ligand L1 led to tweezer-like molecular assemblies.Subsequently,olefinic bonds were introduced to elongate dipyridyl arms obtaining ligand L2.The ligand L2 has two stable conformations,U-shape and Z-shape,which facilitated the formation of different topologies including the tetranuclear macrocycle and Borromean rings with different building blocks in this work.These structures in solid and solution all have been further confirmed by single-crystal X-ray diffraction,NMR analysis,and mass spectrometry.In addition,as an important driving force,π-π stacking interactions not only played a significant role in the stability of structures but also further triggered photothermal conversion in solution.The experimental results demonstrated that compounds 1a and 2 had good NIR photothermal conversion efficiency (11.83% and 17.76%),and further analysis found the photothermal conversion efficiency had a gradual increase in the trend with the π-π stacking interactions increasing.This research expands the application of topological structures in materials science and provides a new idea for the synthesis of novel photothermal conversion materials.

2-channel all optical demultiplexer based on photonic crystal ring resonator

In this paper, we proposed a 2-channel demultiplexer based on photonic crystal ring resonator （PCRR）. For performing wavelength selection, we used two ring resonators, two different wavelengths were obtained by using two resonant rings with different values for the radius of dielectric rods. All the simulations and calculations have been done using Rsoft Photonic CAD software, which employs finite difference time domain （FDTD） method. The output channels were respectively at 1590.8 and 1593.8nm, correspondingly had the quality factors of 7954 and 3984, the crosstalk values of -22 and -11 dB separately. The total footprint of our proposed structure is 681.36 μm2. Results suggest that 2-channels in the proposed structure are characterized with high transmission efficiency and low band width, resulting in a very sharp output spectrum and high quality factor values.

On π-Regular Rings with Involution

A ring R is π-regular if for every a in R, there is a positive integer n such that a^n R is generated by an idempotent. In this paper, we introduce the notion of π-＊-regular rings, which is the ＊-version of π-regular rings. We prove various properties of π-＊-regular rings, and establish many equivalent characterizations of abelian π-＊-regular rings.

PRESTABILIZATION FOR K_1U~ε OF A-2-FOLD RINGS

Vaserstein introduced the K1-functor for the unitary groups over the associative ring with involution, studied the stabilization of unitary K1 for some rings with the stable range condition; and particularly described the prestabilization for K1Uε of local rings. In this report, we study the prestabilization for K1Uε of a class of rings satisfying the condition Sr（R） ≤1 which is introduced by Vaserstein and Bass.

Carboalumination-Epoxide Ring Opening for the Formation of 1,4-Disubstituted （Z）-3,6-Alkadienols

Allylalumination of alkynes （i.e. forming Negishi＇s （Z）-alkenyl dialkylalane） followed by alkenylation of epoxides provides 1,4-disubstituted （Z）-3,6-alkadienols. The alkenylation can be facilitated by the presence of a neighbouring coordinating group in the epoxides. This ＂one-pot＂ approach has been successfully applied in the large-scale production of C 10--C 15 fragment of 9,10-didehydroepothilone D （a synthetic epothilone analog as an anti-cancer agent in phase 2 clinical trials）.

A facile approach for the construction of the oxetane ring from 5α-acyloxy-Δ^(4(20)) - taxoids

An oxetane ring can be constructed from 5α-acyloxy-Δ4(20)-taxoids. Hie facile intramolecular acyl migration from 5- to 20-position under slightly basic conditions enabled the construction of the oxetane ring in a convenient short cut, whereas the acyl migration from 2- to 20-position left the 2-hydroxyl accessible to a later benzoylation. An unexpected five-mem-bered 4-O, 20- O sulfite ring was formed in the attempted construction of the oxetane ring with 5α-triflate as a leaving group. After the construction of the oxetane ring, treatment with strong base LiHMDS and acetyl chloride gave the expected 4-O-acetate while treatment with acetic anhydride and DMAP gave a 4-O-acetoacetate.

利用酵母双杂交系统筛选油菜ATP6的相互作用因子

甘蓝型油菜波利马(Brassica napus pol.)细胞质雄性不育系是一种很有实用价值的油菜不育类型.目前关于其分子机制的研究已证实,线粒体ATP合成酶的一个亚基ATP6与其雄性不育相关.本实验以ATP6作为诱饵蛋白,应用酵母双杂交共转化的方法筛选与ATP6相互作用的蛋白质.在获得的阳性克隆中,发现了一个与拟南芥中未知基因AT3G47550所编码的蛋白质具有较高同源性的蛋白质.它含有RING HC的结构,可能在泛素-蛋白质降解途径与细胞质雄性不育间建立起了某种联系.

Investigation on 3Dt wake flow structures of swimming bionic fish

A bionic experimental platform was designed for the purpose of investigating time accurate three-dimensional flow field, using digital particle image velocimetry （DSPIV）. The wake behind the flapping trail of a robotic fish model was studied at high spatial resolution. The study was performed in a water channel. A robot fish model was designed and built. The model was fixed onto a rigid support frame- work using a cable-supporting method, with twelve stretched wires. The entire tail of the model can perform prescribed motions in two degrees of freedom, mainly in carangiform mode, by driving its afterbody and lunate caudal fin respectively. The DSPIV system was set up to operate in a trans- lational manner, measuring velocity field in a series of parallel slices. Phase locked measurements were repeated for a number of runs, allowing reconstruction of phase average flow field. Vortex structures with phase history of the wake were obtained. The study reveals some new and complex three-dimensional flow structures in the wake of the fish, including ＂reverse hairpin vortex＂ and ＂reverse Karman S-H vortex rings＂, allowing insight into physics of this complex flow.

Discovery of the low temperature phase barium metaborate (BBO) and its significance in the search for new type nonlinear optical materials

1 History of discovery of the low temperature phase barium metaborate （BBO）——an excel-lent new-type ultraviolet radiation frequency-doubling crystalline materialTHE first laser excitation in 1960 with ruby （α-Al2O3: Cr） as a laser crystal and the first dou-bling of frequency （347. 15 nm） in 1961 by irradiating quartz crystal （α-SiO2） with a 694. 3nm laser beam have laid the basis for the study of laser and nonlinear optical （NLO） crystals,