Intrinsic correlation between the generalized phase equilibrium condition and mechanical behaviors in hydrate-bearing sediments

The phase equilibrium and mechanical behaviors of natural gas hydrate-bearing sediment are essential for gas recovery from hydrate reservoirs.In heating closed systems,the temperature-pressure path of hydrate-bearing sediment deviates from that of pure bulk hydrate,reflecting the porous media effect in phase equilibrium.A generalized phase equilibrium equation was established for hydrate-bearing sediments,which indicates that both capillary and osmotic pressures cause the phase equilibrium curve to shift leftward on the temperature-pressure plane.In contrast to bulk hydrate,hydrate-bearing sediment always contains a certain amount of unhydrated water,which keeps phase equilibrium with the hydrate within the hydrate stability field.With changes in temperature and pressure,a portion of pore hydrate and unhydrated water may transform into each other,affecting the shear strength of hydrate-bearing sediment.A shear strength model is proposed to consider not only hydrate saturation but also the change in temperature and pressure of hydrate-bearing sediment.The model is validated by experimental data with various hydrate saturation,temperature and pressure conditions.The deformation induced by partial dissociation was studied through depressurization tests under constant effective stress.The reduction in gas pressure within the hydrate stability field indeed caused sediment deformation.The dissociation-induced deformation can be reasonably estimated as the difference in volume between hydrate-bearing and hydrate-free sediments from the compression curves.

New approach for analysing master equations of generalized phase diffusion models in the entangled state representation

By virtue of the well-behaved properties of the bipartite entangled states representation, this paper analyse and solves some master equations for generalized phase diffusion models, which seems concise and effective. This method can also be applied to solve other master equations.

A Relation of the Noncommutative Parameters in Generalized Noncommutative Phase Space

We introduce the deformed boson operators which satisfy a deformed boson algebra in some special types of generalized noncommutative phase space. Based on the deformed boson algebra, we construct coherent state representations. We calculate the variances of the coordinate operators on the coherent states and investigate the corresponding Heisenberg uncertainty relations. It is found that there are some restriction relations of the noncommutative parameters in these special types of noncommutative phase space.

Complementary Pass-Transistor Adiabatic Logic Circuit Using Three-Phase Power Supply

A new low power quasi adiabatic logic,complementary pass transistor adiabatic logic (CPAL),is presented.The CPAL circuit is driven by a new three phase power clock,and its non adiabatic loss on output loads can be effectively reduced by using complementary pass transistor logic and transmission gates.Furthermore,the minimization of the energy consumption can be obtained by choosing the optimal size of bootstrapped nMOS transistors,thus it has more efficient energy transfer and recovery.A three phase power supply generator with a small control logic circuit and a single inductor is proposed.An 8 bit adder based on CPAL is designed and verified.With MOSIS 0 25μm CMOS technology,the CPAL adder consumes only 35% of the dissipated energy of a 2N 2N2P adder and is about 50% of the dissipated energy of a PFAL adder for clock rates ranging from 50 to 200MHz.

AN EASY-TO-MAKE OZONE GENERATOR FOR THE IMMOBILIZATION OF STATIONARY PHASES IN GC CAPILLARY COLUMNS

An easy-to-make ozone generator which can be made with readily available materials is proposed. Concentration of the ozone prepared with this generator could reach that of ozone in equilibrium with oxygen. Cured with the ozone thus prepared, GC capillary columns with immobilized SE-54 phase and excellent chromatographic performance were successfully prepared.

New bounds of (s,S) policies in periodical review inventory systems

We study the stochastic inventory problem with optimal （s,S） policies.In a finite horizon model with lost sales,we establish new lower and upper bounds of s and S.These bounds have structural implications for the optimal solutions.Consequently,when demand has a generalized phase type distribution,there are no more than a pre-determined number of minima.Similar bounds can also be found for the system where unsatisfied demand is backordered instead of lost sales.

ALow-order Model of Two-dimensional Fluid Dynamics on the Surface of a Sphere

Without any other approximations apart from the spectral method which is employed,the energy spectra corresponding to two kinds of'negative temperatures'are simulated with a symmetric trapezium truncation.The simulated results with either of the two negative temperatures are reasonably consistent with those from the statistical theory of turbulence.The more usual case for two positive temperatures evolves differently from the theoretical prediction.The viscosity influence on the ergodicity is discussed. It is shown that two--dimensional(2D)ideal flows on thesphere have a less pronounced tendency to be ergodic than those on planar geometry due to the curvature of thespherical surface that weakens the interaction between different parts of the flow,enabling these parts to behave inmore relative isolation. The expressions for the standard deviations from a canonical ensemble for the two differentoptions of coefficients are shown to be proportional to in(N is the total number of independent modes in the system),independent of the initial conditions of the system.

Synchronous Vibration Suppression of Magnetic Bearing Systems without Angular Sensors

Active Magnetic Bearing(AMB)levitates rotor by magnetic force without friction,and it can provide active control force to suppress vibration while rotating.Most of vibration suppressing methods need angular speed sensors to obtain rotating speed,but in many occasions,angular speed sensor is difficult to install or is difficult to guarantee reliability.This paper proposed a vibration suppressing strategy without angular speed sensor based on generalized integrator and frequency locked loop(GI-FLL)and phase shift generalized integrator(PSGI).GI-FLL and high-pass filter estimate frequency from control current,PSGI is applied to generate compensating signal.Firstly,model of AMB system expressed by transfer function is established and effect of centrifugal force is analyzed.Then,principle and process of vibration suppressing strategy is introduced.Influence of parameters are analyzed by root locus and bode diagram.Simulation results display the process of frequency estimation and performance of displacement.Experiments are carried on a test rig,results of simulations and experiments demonstrate the effectiveness of proposed vibration suppressing strategy.

Low phase noise and quasi-tunable millimeter-wave generator using a passively In As/InP mode-locked quantum dot laser

A low phase noise millimeter-wave(MMW) signal generator is proposed and experimentally demonstrated with a C-band passively Fabry-Pérot(F-P) quantum dot mode-locked laser. A novel method is proposed to generate low phase noise MMW signal, which is simply based on a commercial off-the-shelf dual-driven Li Nb O3 Mach-Zehnder modulator and a passively F-P quantum dot mode-locked laser. MMW signal with the frequency of 30 GHz, 45 GHz and 90 GHz respectively is obtained experimentally. Single-sideband phase noise of the 30 GHz and 45 GHz MMW signal is-112 d Bc/Hz and-106 d Bc/Hz at an offset of 1 k Hz, respectively. The linewidth of the 30 GHz and 45 GHz MMW signal is about from 225 Hz and 239 Hz. This is considered a very simple MMW generator with a quasi-tunable broadband and ultra-low phase noise.