Dependence of Lower Molding Temperature Limit and Molding Time on Molding Mechanism in Dental Thermoforming

Effectiveness and safety of a sports mouthguard depend on its thickness and material, and the thermoforming process affects these. The purpose of this study was to clarify the effects of differences in molding mechanisms on the lower molding temperature limit and molding time in dental thermoforming. Ethylene vinyl acetate resin mouthguard sheet and two thermoforming machines;vacuum blower molding machine and vacuum ejector/pressure molding machine were used. The molding pressures for suction molding were −0.018 MPa for vacuum blower molding and −0.090 MPa for vacuum ejector molding, and for pressure molding was set to 0.090 MPa or 0.450 MPa. Based on the manufacturer’s standard molding temperature of 95˚C, the molding temperature was lowered in 2.5˚C increments to determine the lower molding temperature limit at which no molding defects occurred. In order to investigate the difference in molding time depending on the molding mechanism, the duration of molding pressure was adjusted in each molding machine, and the molding time required to obtain a sample without molding defects was measured. The molding time of each molding machine were compared using one-way analysis of variance. The lower molding temperature limit was 90.0˚C for the vacuum blower machine, 77.5˚C for the vacuum ejector machine, 77.5˚C for the pressure molding machine at 0.090 MPa, and 67.5˚C for the pressure molding machine at 0.45 MPa. The lower molding temperature limit was higher for lower absolute values of molding pressure. The molding time was shorter for pressure molding than for suction molding. Significant differences were observed between all conditions except between the pressure molding machine at 0.090 MPa and 0.45 MPa (P < 0.01). A comparison of the differences in lower molding temperature limit and molding time due to molding mechanisms in dental thermoforming revealed that the lower molding temperature limit depends on the molding pressure and that the molding time is longer for suction molding than for pressure molding.

Non-linear buffeting response analysis of long-span suspension bridges with central buckle

The rigid central buckle employed in the Runyang Suspension Bridge (RSB) was the first time it was used in a suspension bridge in China. By using a spectral representation method and FFT technique combined with measured data,a 3D fluctuating wind field considering the tower wind effect is simulated. A novel FE model for buffeting analysis is then presented,in which a specific user-defined Matrix27 element in ANSYS is employed to simulate the aeroelastic forces and its stiffness or damping matrices are parameterized by wind velocity and vibration frequency. A nonlinear time history analysis is carried out to study the influence of the rigid central buckle on the wind-induced buffeting response of a long-span suspension bridge. The results can be used as a reference for wind resistance design of long-span suspension bridges with a rigid central buckle in the future.

Study on the optical limiting properties of the mixed liquid of carbon black suspensions and green tea solution by multi-pulse laser

The optical limiting properties of the mixed liquid of carbon black suspensions （CBS） and green tea solution were studied by using an 8 ns laser pulse at 532 nm. The optical limiting effects of the CBS and mixed liquid have been compared between 5 and 10 Hz repetition frequencies with nanosecond laser pulse. The experimental results indicate that the optical limiting threshold of the sample with the incidence laser at 10 Hz repetition frequency is lower than at 5 Hz repetition frequency. The possible reasons for the influence of the repetition frequency on the samples are discussed. And by observing the optical radiant distributions when the laser pulse passing through different samples, a possible mechanism for the observed effects is suggested. At the same time, the result shows that the optical limiting of CBS is the dominant factor to optical limiting of the mixed liquid.

Quantum speed limit time and entanglement in a non-Markovian evolution of spin qubits of coupled quantum dots

Quantum speed limit time and entanglement in a system composed of coupled quantum dots are investigated.The excess electron spin in each quantum dot constitutes the physical system(qubit).Also the spin interaction is modeled through the Heisenberg model and the spins are imposed by an external magnetic field.Taking into account the spin relaxation as a non-Markovian process,the quantum speed limit and entanglement evolution are discussed.Our findings reveal that increasing the magnetic field leads to the faster quantum evolution.In addition,the temperature increment causes the longer quantum speed limit time as well as the entanglement degradation.

Dynamics simulation of electrorheological suspensions in poiseuille flow field

Based on a modified Maxwell-Wagner model,molecular dynamics is carried out to simulate the structural changes of ER(electrorheological) suspensions in a poiseuille flow field.The simulation results show that the flow assists in the collection of particles at the electrodes under a low pressure gradient,and the negative ER effect will show under a high pressure gradient.By analyzing the relationship curves of the shear stress and the pressure gradient in different relaxation time,it is found that for the same kind of ER suspensions materials,there is an optimal dielectric relaxation frequency.

Stability and Neimark-Sacker bifurcation analysis of a food-limited population model with a time delay

In this paper,a kind of discrete delay food-limited model obtained by the Euler method is investigated,where the discrete delay τ is regarded as a parameter.By analyzing the associated characteristic equation,the linear stability of this model is studied.It is shown that Neimark-Sacker bifurcation occurs when τ crosses certain critical values.The explicit formulae which determine the stability,direction,and other properties of bifurcating periodic solution are derived by means of the theory of center manifold and normal form.Finally,numerical simulations are performed to verify the analytical results.

Quantum speed limit time of a non-Hermitian two-level system

We investigated the quantum speed limit time of a non-Hermitian two-level system for which gain and loss of energy or amplitude are present. Our results show that, with respect to two distinguishable states of the non-Hermitian system, the evolutionary time does not have a nonzero lower bound. The quantum evolution of the system can be effectively accelerated by adjusting the non-Hermitian parameter, as well as the quantum speed limit time can be arbitrarily small even be zero.

Quantum speed limit time of a two-level atom under different quantum feedback control

We investigate the quantum speed limit time （QSLT） of a two-level atom under quantum-jump-based feedback control or homodyne-based feedback control. Our results show that the two different feedback control schemes have different influences on the evolutionary speed. By adjusting the feedback parameters, the quantum-jump-based feedback control can induce speedup of the atomic evolution from an excited state, but the homodyne-based feedback control cannot change the evolutionary speed. Additionally, the QSLT for the whole dynamical process is explored. Under the quantum-jump-based feedback control, the QSLT displays oscillatory behaviors, which implies multiple speed-up and speed-down processes during the evolution. While, the homodyne-based feedback control can accelerate the speed-up process and improve the uniform speed in the uniform evolution process.

Crack growth time dependence analysis of granite under compressive-shear stresses state

The curves of crack relative length lib and crack growth time t of granite were gained under compressive stresses state according to subcritical crack growth parameters and crack stability growth equation by double-torsion constant displacement load relaxa- tion method. The relations between crack relative length and the crack growth time were discussed under different stresses and different crack lengths. The results show that there is a turning point on curve of crack relative length lib and crack growth time of granite. The slope of curve is small when crack relative length is less than the vertical coordinate of the point, and crack grows stably in this case. Cracks grow, encounter and integrate catastro- phically when crack relative length is more than the vertical coordinate of the point, and there is not a gradual stage from crack stability growth to crack instability growth, i.e. rock mass instability is sudden. The curves of crack relative length lib and crack growth time t of granite move to right with decrease of stress σl or crack length a, which implies that limit time increases consequently. The results correspond to practicality.

Non-stationary Buffeting Response Analysis of Long Span Suspension Bridge Under Strong Wind Loading

The non-stationary buffeting response of long span suspension bridge in time domain under strong wind loading is computed. Modeling method for generating non-stationary fluctuating winds with probabilistic model for non-stationary strong wind fields is first presented. Non-stationary wind forces induced by strong winds on bridge deck and tower are then given a brief introduction. Finally,Non-stationary buffeting response of Pulite Bridge in China,a long span suspension bridge,is computed by using ANSYS software under four working conditions with different combination of time-varying mean wind and time-varying variance. The case study further confirms that it is necessity of considering non-stationary buffeting response for long span suspension bridge under strong wind loading,rather than only stationary buffeting response.

Determination of the Financing Scale,Time Limit and Returns from the Investment in BOT Projects

The key aspect to the successful implementation of BOT concept is the raising of finance by project sponsor,so financial engineering techniques and capital structuring skills are required to find the proper mix of debt and equity.The capital structure and present a model to determine the equity level from the aspects of financing scale,construction time and return on investment are analyzed.The resulting model can help the sponsor to avoid the capital risk,and offer the government a criterion to evaluate management ability of the sponsor.To show the application and availability of this model,a case study is conducted.Thus,this paper is concern with the determination of financing scale,construction time,and return on investment which would assist the sponsor to ensure that the equity level for optimal capital structure is available prior to the implementation stage in BOT project operation.

Extention of Time Limit Mandated by SIPO(as basically limited to one extention and for two months at most)

The State Intellectual Poperty Office has announcedan amendment to Sec.5,Paragrph 4.2.of Chapter 7 ofExamination Guidelines.According to the newregulations,for making a respon to an office actionduring the prosecution of a patent application,only a firstrequest for a two-month extension of time can be basicallyallowed upon payment of official fee of RMB300(aboutUSD36).For further extension after the first one,onlyanother request for one or two months,at most twomonths,would be possibly petitioned together with a copyof the client’s instructions of the further extension and

NUMERICAL ANALYSIS OF COMPLEX FLOW OF FIBRE SUSPENSIONS IN A VISCOELASTIC FLUID

Research efforts made so far to simulate fibre suspension flows are limited to fibre suspensions in Newtonian fluids.Though short fibre composites are mostly made of polymers,lack of suitable constitutive equations for fibre suspensions in viscoelastic fluids frustrates attempts to simulate flows of these suspensions. A preliminary work done by the author led to a constitutive equation for semiconcentrated fibre suspensions in the Oldroyd-B fluid.This paper describes the mathematical formulation of the flow problems for such a suspension and the numerical procedure to solve them.Some numerical results of flow past a sphere in a tube are also presented.

Long-time limit behavior of the solution to an atom's master equation

We study the long-time limit behavior of the solution to an atom＇s master equation. For the first time we derive that the probability of the atom being in the α-th （α = j ＋ 1 -jz, j is the angular momentum quantum number, jz is the z-component of angular momentum） state is {（1 - K/G）/[1 - （K/G）2j＋1]}（K/G）^α-1 as t → ＋∞, which coincides with the fact that when K/G 〉 1, the larger the a is, the larger the probability of the atom being in the α-th state （the lower excited state） is. We also consider the case for some possible generaizations of the atomic master equation.

Coherence Modified for Sensitivity to Relative Phase of Real Band-Limited Time Series

As is well known, coherence does not distinguish the relative phase of a pair of real, sinusoidal time series;the coherence between them is always unity. This behavior can limit the applicability of coherence analysis in the special case where the time series are band-limited (nearly-monoch- romatic) and where sensitivity to phase differences is advantageous. We propose a simple mod-ification to the usual formula for coherence in which the cross-spectrum is replaced by its real part. The resulting quantity behaves similarly to coherence, except that it is sensitive to relative phase when the signals being compared are strongly band-limited. Furthermore, it has a useful interpretation in terms of the zero-lag cross-correlation of real band-passed versions of the time series.

PHASE RETRIEVAL OF TIME-LIMITED SIGNALS

The problem of reconstructing a signalφ（x） from its magnitude ｜φ（x）] isof considerable interest to engineers and physicists. This article concerns the problem of determining a time-limited signal f with period 2π when ｜f（eix）l is known for x∈[-π,π]. It is shown that the conditions ｜g（eix）｜ = ｜f（eix）｜ and ｜g（ci（x＋b）） -g（eix）｜ =f（ei（x＋b）） - f（eix）｜, b ≠ 27π, together imply that either g = wf or g = v f, where both w and v have period b. Furthermore, if b/2π is irrational then the functions w and v b is rational then w takes the form reduce to some constants c1 and c2, respectively; ifb/2π is rational then w takes the form w=elexB1（e1x）B2（elx）and v takes the form ei（x2πN/b＋a）B1（elx）B2（elx）,where B1 and B2 are Blaschke products.

OUTPUT REGULATION OF THE GENERAL NONLINEARDISCRETE-TIME SYSTEM

With the use of centre manifold and dynamic system theory, the necessary and sufficient conditions are obtained for the solvabilities of the output regulator problems for the general nonlinear discrete-time system. This work generalizes and refines the corresponding results by Isidori and Byrnes on the affine nonlinear continuous-time 'system.

PERFORMANCE ANALYSIS OF POLLING SYSTEMS WITH LIMITED SERVICE

This paper analyzes a queue mode] of the polling system with limited service (K=1) in discrete time. By the imbedded Markov chain theory and the probability generating function method, the mean values of queue length and message waiting time are explicitly obtained. Also, we give the simulation results. The results obtained by H. Tagai (1985) are revised.

Application of high temperature heat pipe in hypersonic vehicles thermal protection

In order to develop further the application of high temperature heat pipe in hypersonic vehicles thermal protection, the principles and characteristics of high temperature heat pipe used in hypersonic vehicles thermal protection were introduced. The methods of numerical simulation, theory analysis and experiment research were utilized to analyze the frozen start-up and steady state characteristic of the heat pipe as well as the machining improvement for fabricating irregularly shaped heat pipe which is suitable for leading edge of hypersonic vehicles. The results indicate that the frozen start-up time of heat pipe is long （10 min） and there exists large temperature difference along the heat pipe （47 ℃/cm）, but the heat pipe can reduce the temperature in stagnation area of hypersonic vehicles from 1 926 to 982 ℃ and work normally during 1 000-1 200℃. How to improve the maximum heat transfer capability and reduce the time needed for start-up from frozen state of the heat pipe by optimizing thermostructure such as designing of a novel wick with high performance is the key point in hypersonic vehicles thermal protection of heat pipe.