Molecular Dynamics Simulation on Characteristics of Decomposition of Methane Hydrate in the Presence of Hydrogen Peroxide Solution

In this work, the characteristics of the decomposition of methane hydrate Structure I (SI) in the presence of hydrogen peroxide solution is investigated using the molecular dynamics simulation. The mechanism of the transformation process from the solid hydrate to the liquid is analyzed with the effect of hydrogen peroxide (HP) solution. In addition, the effect of ethylene glycol (EG) with the same molar concentration with HP on the methane hydrate dissociation is also studied. The results illustrate that both HP and EG promote well the hydrate dissociation. The work provides the important reference value for the experimental investigation into the promotion effect of HP on the hydrate dissociation.

Molecular Dynamics Simulation of Methane Hydrate Dissociation Process in the Presence of Thermodynamic Inhibitor

The dissociation of methane hydrate in the presence of ethylene glycol (11.45 mol.L-1) at 277.0 K was studied using canonical ensemble (NVT) molecular dynamics simulations. Results show that hydrate dissociation starts from the surface layer of the solid hydrate and then gradually expands to the internal layer. Thus, the solid structure gradually shrinks until it disappears. A distortion of the hydrate lattice structure occurs first and then the hydrate evolves from a fractured frame to a fractional fragment. Finally, water molecules in the hydrate construction exist in the liquid state. The inner dissociating layer is, additionally, coated by a liquid film formed from outer dissociated water molecules outside. This film inhibits the mass transfer performance of the inner molecules during the hydrate dissociation process.

On the representation of an inclined Gaussian beam

In most contemporary optics courses, Gaussian beams are demonstrated in the form of propagation along one coordinate axis. This is referred to as the conventional representation and is in fact a special form. In this paper, we derive the general representation of a Gaussian beam propagating obliquely to the coordinate axis, by performing a coordinate rotation transformation on the conventional representation. When doing so on the beam parameters, a restrictive condition has to be taken into account. Without this condition, the expressions for the beam parameters after the rotation are not consistent with the conventional ones.

A NEW METHOD FOR MEASURING THE EFFECTIVE DIFFUSION CONSTANT OF 2-DIMENSIONAL ELECTRONS IN THE PRESENCE OF MAGNETIC-FIELDS

The transient charge response Q(t) of a two-dimensional electron gas (2DEG) in GaAs/AlxGa1-xAs heterostructures to a small pulse of the gate voltage, applied between the top gate and source electrodes in a Corbino structure, was employed to directly measure the effective diffusion constant of a 2DEG in the quantum Hall regime. The measured diffusion constant D showed a drastic change as the magnetic field was swept through the integer fillings of the Landau levels.

A Low Power Dissipation Wide-Band CMOS Frequency Synthesizer for a Dual-Band GPS Receiver

This paper presents a wide tuning range CMOS frequency synthesizer for a dual-band GPS receiver,which has been fabricated in a standard 0.18μm RF CMOS process. With a high Q on-chip inductor, the wide-band VCO shows a tuning range from 2 to 3.6GHz to cover 2.45 and 3.14GHz in case of process corner or temperature variation,with a current consumption varying accordingly from 0.8 to 0.4mA,from a 1.8V supply voltage. Measurement results show that the whole frequency synthesizer consumes very low power of 5.6mW working at L1 band with in-band phase noise less than - 82dBc/Hz and out-of-band phase noise about - ll2dBc/Hz at 1MHz offset from a 3. 142GHz carrier. The performance of the frequency synthesizer meets the requirements of GPS applications very well.

A High Speed, 12-Channel Parallel, Monolithic Integrated CMOS OEIC Receiver

The design and fabrication of a high speed, 12-channel monolithic integrated CMOS optoelectronic integrated circuit(OEIC) receiver are reported.Each channel of the receiver consists of a photodetector,a transimpedance amplifier,and a post-amplifier.The double photodiode structure speeds up the receiver but hinders responsivity.The adoption of active inductors in the TIA circuit extends the-3dB bandwidth to a higher level.The receiver has been realized in a CSMC 0.6μm standard CMOS process.The measured results show that a single channel of the receiver is able to work at bit rates of 0.8～1.4Gb/s. Altogether, the 12-channel OEIC receiver chip can be operated at 15Gb/s.