Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber

Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.

Scheme for Cloing a Three-Particle GHZ Class State with Assistance

Our concern is to design an assisted-clone scheme which can produce a perfect copy of a three-particle Oreenberger-Horne-Zeilinger （GHZ） class state with a high probability. In the first stage of the protocol, the sender teleports the input state to the receiver by using three EPR pairs as the quantum channel. In the second stage of the protocol, a novel set of mutually orthogonal basis vectors is constructed. With the assistance of the preparer through a three-particle projective measurement under this basis, the perfect copy of an original state can be reestablished by the sender with the probability 1/2. Moreover, the classical communication cost of the scheme is also calculated.

EXISTENCE OF THREE-SOLUTIONS FOR SECOND-ORDER DIFFERENTIAL EQUATIONS WITH NONLINEAR BOUNDARY VALUE CONDITIONS

The paper deals with the existence of three- solutions for the second- order differential equations with nonlinear boundary value conditions x″=f(t,x,x′) , t∈ [a,b], g1(x(a) ,x′(a) ) =0 , g2 (x(b) ,x′(b) ) =0 , where f :[a,b]× R1× R1→ R1,gi:R1× R1→ R1(i=1 ,2 ) are continuous functions.The methods employed are the coincidence degree theory.As an application,the sufficient conditions under which there are arbitrary odd solutions for the BVP are obtained

A combined numerical model of three-dimensional tidal motion and sediment transport in tidal current and its application

A calculation scheme, which combines a horizontal upwind finite element method with vertical implicit differences, is used to establish a three-dimensional mathematical model of tidal motion and sediment transport in tidal current. Compared with those of the relative theoretical formula, the results are satisfactory. The model mentioned above has been applied to the water area of the Lianzhou Bay, Guangxi Province. On the basis of the analysis and comparison with the field data, it shows clearly that the model calculation results are reasonable.

Exact 3D Thermoelastic Solutions for a Penny-Shaped Crack in an Infinite Magnetoelectric Medium

Exact solutions of three-dimensional(3D)crack problems are much less in number than those of two-dimensional ones,especially for multi-field coupling media exhibiting a certain kind of material anisotropy.An exact3Dthermoelastic solution has been reported for a uniformly heated penny-shaped crack in an infinite magnetoelectric space,with impermeable electromagnetic conditions assumed on the crack faces.Exact 3Dsolutions for the penny-shaped crack subjected to uniform or point temperature load are further presented here when the crack faces are electrically and magnetically permeable.The solutions,obtained by the potential theory method,are exact in the sense that all field variables are explicitly derived and expressed in terms of elementary functions.Along with the previously reported solution,the limits or bounds of the stress intensity factor at the crack-tip for a practical crack can be identified.

A baseband circuit for wake-up receivers with double-mode detection and enhanced sensitivity robustness

This paper proposes a baseband circuit for wake-up receivers with double-mode detection and enhanced sensitivity robustness for use in the electronic toll collection system.A double-mode detection method,including amplitude detection and frequency detection,is proposed to reject interference and reduce false wake-ups.An improved closed-loop band-pass filter and a DC offset cancellation technique are also newly introduced to enhance the sensitivity robustness.The circuit is fabricated in TSMC 0.18μm 3.3 V CMOS technology with an area of 0.12 mm2.Measurement results show that the sensitivity is -54.5 dBm with only a±0.95 dBm variation from the 1.8 to 3.3 V power supply,and that the temperature variation of the sensitivity is±1.4 dBm from -50 to 100℃. The current consumption is 1.4 to 1.7μA under a 1.8 to 3.3 V power supply.

Accuracy of Low-level Surface in Hierarchical Construction of Potential Energy Surface

The effects of low-level PES on the overall accuracy of the final surface constructed by using hierarchical construction were investigated with the constructions of a number of global surfaces for the H3 system at UHF （UMP2, DFT-B3LYP, UCCSD（T））/vtz, and UCCSD（T）/avqz levels of theory. The total reaction probabilities for the H＋H2 reaction calculated on these surfaces revealed that the accuracy of UCCSD（T）/avqz surface is very close to the well-known BKMP2 surface, while the UCCSD（T）/vtz PES has a slightly higher barrier. In contrast, the low-level theories （UHF, UMP2, DFT-B3LYP） with vtz basis set can only provide a qualitative description of this simplest reaction despite the fact that they are widely used to study reactions in complex systems. On the other hand, although these theories are not accurate on describing the reaction, they can be used to provide the low- level PESs for hierarchical construction of the UCCSD（T）/avqz PES with the number of UCCSD（T）/avqz energies substantially reduced.

Application of spiral CT image 3D reconstruction in severe talar neck fracture

Objective： To explore the application of the spiral computerized tomography （CT） image three-dimensional （ 3D ） reconstruction technique associated with the conventional radiography in the diagnosis and treatment of severe talar neck fracture. Methods： Using the multi-slice spiral CT image 3D reconstruction technique, we analysed Ⅱ cases of talar neck fracture. The fractures were reduced and fixed through a minimal incision and internal fixation with titanium cannulated lag screws. Results. In the Ⅱ cases, the results of CT image 3D reconstruction were in concordance with plain radiograph in 6 case of Hawkins type Ⅱ. And the remaining 5 cases of Hawkins types Ⅲ and Ⅳ could not be classified exactly only by radiographs, one of whom was misdiagnosed. After using the CT image 3D reconstruction, the 5 cases were classified exactly before osteosynthesis. The classifications of these Ⅱ cases were confirmed finally by surgical findings. The duration of operation were 45-Ⅰ40 min, averaging 8Ⅰ min （including the duration of C-arm fluoroscopy）. X-ray exposure time was 6-58 seconds, averaging 22 seconds. The blood loss was less than Ⅰ00 ml. The fracture union was achieved in 3 months. No nonunion, talus avascular necrosis or joint surface collapse occurred. Postoperative follow-up was from Ⅰ to 25 months. According to Hawkins score, excellent result was found in 6 type Ⅱ cases and Ⅰ type Ⅲ case; good result in I type Ⅲ case with both medial and lateral malleolar fracture, Ⅰ type Ⅲ with medial malleolus fractures and Ⅰ open type Ⅲ; fair result in Ⅰ open type Ⅳ with lateral malleolus fracture. Conclusions ： By using the multl-slice spiral CT image 3D reconstruction associated with radiography to diagnose and treat severe talar neck fractures, the accuracy of diagnosis can be improved obviously. Based on this technique, more consummate operational plan can be designed and performed so as to achieve a better therapeutic effect.

HOMOCLINIC BIFURCATION WITH CODIMENSION 3

First it is proved that both the integral of the divergence and the Melnikov function are invariants of the C2 transformation. Then, the problem of the planar homoclinic bifurcation with codimension 3 is considered. It is proved that, in a small neighborhood of the origin in the parameter space of a Cr (r≥5) system, there exist exactly two Cr-1 semi- stable- limit- cycle branching surfaces, and their common boundary is a unique Cr-1 three-multiple- limit-cycle branching curve. The bifurcation pictures and the asymptotic expansions of the bifurcation functions are given. The stability criterion for the homoclinic loop is also obtained when the integral of the divergence is zero. The proof of the auxiliary theorems will be presented in [16].

Design and analysis of a structure-based microstrip bandpass filter

A structure-based microstrip passband filter with the center frequency of 2.6 GHz was put forward by using double-mode resonator based on defected ground structure （DGS） technology. A double-mode coupling resonator combined with DGS structure was used to achieve the resonance frequency and the filter size. CST microwave studio was used to optimize the attenuation performance to get the filter parameters. A structure-based passband filter was fabricated. Simulation is consistent with the measurement. Performance shows that the proposed filter could be suitable for the time division-long term devolution （TD-LTE） microwave systems at 2.6 GHz.

Fracture behavior of 304 stainless steel coatings by cold gas dynamic spray

304 stainless steel coating was deposited on the Interstitial-Free steel substrate by cold gas dynamic spraying （CGDS）. Three-point bending test of the cold sprayed 304 stainless steel coating was tested by SHIMADZU electro-hydraulic servo-controlled fatigue testing machine and the fracture morphology was examined by scanning electron microscopy. The results showed that the fracture behavior of the cold sprayed 304 stainless steel coating was brittleness fracture. The crack in the coating occurred in the interfaces between particles and the crack extended to the internal of the coating with the increase of the load. When the crack has extended to the combination interface between coating and substrate, the crack extended to the two sides. The microstructure and mechanical property of the cold sprayed 304 stainless steel coating have been optimized after heat treatment.