Influence of Phosphorus Content and Magnetic Annealing on Soft Magnetic Properties of Electrodeposited Amorphous FeMnP Alloy Films

In this work, we investigated the influence of phosphorus and magnetic anneal on the soft magnetic properties of electrodeposited FeMnP alloy films prepared by changing sodium hypophosphite concentrations. X-ray diffraction radiation patterns showed an amorphous structure of electrodeposited alloy films. The saturation magnetization and coercivity value decreased from 586 emu/cc to 346 emu/cc, and 52 Oe to 18 Oe, with the P content increased, respectively. The absorption resonance peak became broad as the P content increased, and the natural resonance frequency decreased from 1.8 GHz to 0.6 GHz, with the P content increasing. Magnetic annealing of samples reduced the magnetic damping, and natural resonance frequency increased by about 1.8 GHz and 3.5 GHz for the sample with lower and higher P content. The film structure with lower P content changed at 300˚C, while the structure remains unchanged for the films with higher P content. Thus, the crystallization temperature could depend on the P content in the film. FeMnP alloy films could be used in high-frequency devices.

Analytical and numerical studies for Seiches in a closed basin with bottom friction

A standing wave oscillation in a closed basin,known as a seiche,could cause destruction when its period matches the period of another wave generated by external forces such as wind,quakes,or abrupt changes in atmospheric pressure.It is due to the resonance phenomena that allow waves to have higher amplitude and greater energy,resulting in damages around the area.One condition that might restrict the resonance from occurring is when the bottom friction is present.Therefore,a modified mathematical model based on the shallow water equations will be used in this paper to investigate resonance phenomena in closed basins and to analyze the effects of bottom friction on the phenomena.The study will be conducted for several closed basin shapes.The model will be solved analytically and numerically in order to determine the natural resonant period of the basin,which is the period that can generate a resonance.The computational scheme proposed to solve the model is developed using the staggered grid finite volume method.The numerical scheme will be validated by comparing its results with the analytical solutions.As a result of the comparison,a rather excellent compatibility between the two results is achieved.Furthermore,the impacts that the friction coefficient has on the resonance phenomena are evaluated.It is observed that in the prevention of resonances,the bottom friction provides the best performance in the rectangular type while functioning the least efficient in the triangular basin.In addition,non-linearity effect as one of other factors that provide wave restriction is also considered and studied to compare its effect with the bottom friction effect on preventing resonance.

Dynamic Analysis of a Single-Column Platform

In this paper, a single-column structure used as well-head platform is studied. The loads of wave and current exerted on the single-column will be greatly reduced, therefore the cost of the structure will be decreased. The advantages of the single-column structure compared with ordinary jacket structure are explained. A dynamic analysis of this type of structure is made and some problems related to dynamic analysis are solved. In order to check the reliability of computation theory and programme, model tests have been carried out. However, as space is limited, the conclusion of tests will be introduced in another paper. Therefore, this type of structure is applicable for proctical engineering.

Natural frequency for exponential shaped thermoacoustic resonator

The two-dimensional nonlinear acoustic field of eleven exponential shaped res- onators was simulated with a computational fluid dynamics software Fluent. The influence of driving frequency and driving intensity on pressure in resonator as well as its natural frequency was investigated. The relationship between natural frequency and theoretical calculation res- onance frequency was also explored. It is found that beating phenomena can be observed in the resonator when the driving frequency deviates from the natural frequency. Moreover, the natural frequency of resonator increases with the increasing of driving intensity, which shows a hard spring effect. However, the driving intensity plays little effect on natural frequency and the natural frequencies are smaller than the theoretical calculation values in any driving intensity. Meanwhile, a formula between the natural frequency and its first-order resonance frequency from theoretical calculation was obtained by linear fitting for all these exponential shaped resonators under consideration. It is also found that the highest pressure amplitude and highest pressure ratio can be obtained from the exponential shaped resonator of m = 2.8 under the same driving intensity. Moreover, the relation between natural frequency and the theoretical resonance frequency for m = 2.8-tube is slightly different from other tubes in consideration.

Plasma Pulse Technology: An uprising EOR technique

Conventionally oil recovery factor is too low,which leaves great prospects for the application of enhanced oil recovery(EOR)methods to increase recovery factor.EOR methods are capital intensive and few are environmentally hazardous.So the paper discusses on the alternate enhanced oil recovery technique which has tremendous potential to curb the challenges of conventional EOR methods.Plasma pulse technology(PPT)aided EOR treatment is administered with an electric wireline conveyed plasma pulse generator tool that is run in the well and positioned alongside the perforations.Using energy stored in the generator's capacitors,a plasma arc is created that emits a tremendous amount of heat and pressure for a fraction of a second.This in turn creates a broad band of hydraulic impulse acoustic waves that are powerful enough to clean perforations and near wellbore damage.These waves continue to resonate deep into the reservoir,exciting the fluid molecules and increasing the reservoirs natural resonance to the degree that it can break larger hydrocarbon molecules to smaller one and simultaneously reducing adhesion tension which results in increased mobility of hydrocarbons.The plasma pulse technology has been successfully used on production as well as injection wells.It has been used often as a remedial procedure to increase well's productivity that has been on production for a period of time.This paper throws light on fundamentals of this advancing plasma pulse technology,contrasting it with recent EOR techniques.Effectiveness of treatment in increasing oil recovery,it's applicability to different reservoir types and results achieved so far are also covered in the paper.

A fast transient response low dropout regulator with current control methodology

A transient performance optimized CCL-LDO regulator is proposed.In the CCL-LDO,the control method of the charge pump phase-locked loop is adopted.A current control loop has the feedback signal and reference current to be compared,and then a loop filter generates the gate voltage of the power MOSFET by integrating the error current.The CCL-LDO has the optimized damping coefficient and natural resonant frequency, while its output voltage can be sub-l-V and is not restricted by the reference voltage.With a 1μF decoupling capacitor,the experimental results based on a 0.13μm CMOS process show that the output voltage is 1.0 V;when the workload changes from 100μA to 100 mA transiently,the stable dropout is 4.25 mV,the settling time is 8.2μs and the undershoot is 5.11 mV;when the workload changes from 100 mA to 100μA transiently,the stable dropout is 4.25 mV,the settling time is 23.3μs and the overshoot is 6.21 mV.The PSRR value is more than -95 dB.Most of the attributes of the CCL-LDO are improved rapidly with a FOM value of 0.0097.