Design of a New Acoustic Logging While Drilling Tool

To obtain qualified logging while drilling (LWD) data, a new acoustic LWD tool was designed. Its overall design is introduced here, including the physical construction, electronic structure, and operation flowchart. Thereafter, core technologies adopted in this tool are presented, such as dominant exciting wave bands of dipole source, a sine wave pulse excitation circuit, broadband impedance matching, and an intellectualized active reception transducer. Lastly, we tested this tool in the azimuthal anisotropy module well, calibration well, and normal well, working in the model of the cable, sliding eye, and logging while drilling. Experiments showed that the core technologies achieved ideal results and that the LWD tool obtained qualified data.

Theoretical Analysis of a Vertical Cylindrical Floater in Front of an Orthogonal Breakwater

This study investigates the effect of an orthogonal-shaped reflecting breakwater on the hydrodynamic characteristics of a vertical cylindrical body. The reflecting walls are placed behind the body, which can be conceived as a floater for wave energy absorption. Linear potential theory is assumed, and the associated diffraction and motion radiation problems are solved in the frequency domain. Axisymmetric eigenfunction expansions of the velocity potential are introduced into properly defined ring-shaped fluid regions surrounding the floater. The hydrodynamic interaction phenomena between the body and the adjacent breakwaters are exactly taken into account by using the method of images. Results are presented and discussed concerning the exciting wave forces on the floater and its hydrodynamic coefficients, concluding that the hydrodynamics of a vertical cylindrical body in front of an orthogonally shaped breakwater differ from those in unbounded waters.

Theoretical Evaluation of the Hydrodynamic Characteristics of Arrays of Vertical Axisymmetric Floaters of Arbitrary Shape in front of a Vertical Breakwater

The present paper deals with the analytical evaluation of the hydrodynamic characteristics of an array of vertical axisymmetric bodies of arbitrary shape, placed in front of a reflecting vertical breakwater, which can be conceived as floaters for wave power absorption. At the first part of the paper, the hydrodynamic interactions between the floaters and the adjacent breakwater are exactly taken into account using the method of images, whereas, the interaction phenomena between the floaters of the array are estimated using the multiple scattering approach. For the solution of the problem, the flow field around each floater of the array is subdivided into ring-shaped fluid regions, in each of which axisymmetric eigenfunction expansions for the velocity potential are made. In the second part of the paper, extensive theoretical results are presented concerning the exciting wave forces and the hydrodynamic coefficients for various arrays’ arrangements of axisymmetric floaters. The aim of the study is to show parametrically the effect that the vertical breakwater has on the hydrodynamic characteristics of each particular floater.

Group velocity mismatch at ultrashort electromagnetic pulse propagation in nonlinear metamaterials

The parametric interaction of optical wave pulses in metamaterials is considered in the first approximation of the theory of dispersion. The interaction between the quasi-monochromatic pump wave and the wave pulse at the total frequency with quadratic phase modulation is assumed. The results of calculation of the shape of the spectrum of an excited signal wave at a difference frequency are presented for low frequency pumping. It is shown that the effects of group mismatch in metamaterials lead to a narrowing of the spectrum of the excited wave. With an increase in the modulation degree of a weak exciting wave, the spectrum of the excited wave broadens.

Working-Class Fictions

This chapter explores why working-class fictions flourished in the period from the late 1950s through to the early 1970s and the distinctive contributions that they made to the post-war British and Irish novel. These writers of working-class fiction were celebrated for their bold, socially realistic, and often candid depictions of the lives and desires of ordinary working people. Their works were seen to herald a new and exciting wave of gritty social realism. The narrative focus on the individual signalled a shift in the history of working-class writing away from the plot staples of strikes and the industrial community, striking a chord with a post-war reading public keen to see ordinary lives represented in books in a complex and realistic manner. The cultural significance of such novels was enhanced as they were adapted in quick succession for a mass cinema audience by a group of radical film-makers.

Wave Diffraction on Arrays of Vertical Truncated Cylindrical Bodies

Offshore Wave Energy Converter (WEC) farms are widely deployed as regards the individual isolated devices aiming at maximum wave energy absorption and facilitating installation and power transmission. This paper summarizes the theory behind the hydrodynamic interactions of diffracted waves by a large array of vertical cylinders. The latter exhibits some remarkable hydrodynamic interference effects — near resonant modes — in waves causing large loads in adjacent elements of the array. Numerical results concerning the exciting wave loads for a variety of different array configurations of truncated and bottomless cylinders are presented and the free surface elevation around the elements of the array is evaluated pointing out the near trapped modes.

Surface Plasmon-Polaritons and Transverse Spin Angular Momentum at the Boundary of Hyperbolic Metamaterial with Arbitrary Orientation of the Optical Axis

The possibility is established and the conditions are found for localization of plasmon-polaritons (PPs) near the boundaries of hyperbolic metamaterials (HMs) of both I and II types with arbitrary orientation of the optical axis. It is grounded that such surface PP has the transverse spin momentum which depends on the wavelength of the exciting wave, the orientation of the optical axis of the hyperbolic metamaterial, and dielectric properties of bordered media.

Hydrodynamics of a Free Floating Vertical Axisymmetric Oscillating Water Column Device

This paper aims at presenting a general formulation of the hydrodynamic problem of a floating or restrained oscillating water column device. Three types of first-order boundary value problems are investigated in order to calculate the velocity potential of the flow field around the device. The horizontal and vertical exciting wave forces, the rolling moment, the hydrodynamic parameters, the volume flows, and the drift forces are obtained in order to find the loads on the structure. The efficiency rate of the device is calculated in connection with the absorbed power and the capture length of energy absorption. Finally, the resulting wave motion inside and outside the device and the inner air pressure are examined.

Analysis of Free Vibration Characteristics and Mode Shapes of a Semi-Submersible Platform

The current investigation presents a global natural frequency and mode shape analysis of a semi-submersible platform. The purpose is to evaluate the separation in frequency between the semi-submersible’s global natural frequencies and the exciting wave spectrum. Two types of finite element models are compared: a beam element model and a shell element model. The main differences in the models are the level of resolution in details and model complexity. It is shown that both beam and shell element models can be used for the analysis. However, the beam element model is recommended for a first approximate assessment of the fundamental natural frequency and the interval/spectrum of global resonance frequencies compared to the wave spectrum. The shell element model is recommended when a more thorough analysis is required. In addition, the natural frequencies of the semi-submersible are calculated for free vibration in air. The fundamental frequency was 1.9 Hz for the beam element model and 1.5 Hz for the shell element model. When weights corresponding to a submerged structure in operation mode are considered, including the effects of added mass, the fundamental frequency for the first mode using the beam element model was decreased to 0.7 Hz, and to 0.6 Hz when using the shell element model. When compared to the DNV world wave spectrum’s highest frequency of 0.29 Hz it is concluded that the natural frequencies of the semi-submersible are at a sufficient distance from the exciting wave spectrum.