Wave Radiation by a Floating Body in Water of Finite Depth Using an Exact DtN Boundary Condition

The present paper focuses on the wave radiation by an oscillating body with six degrees of freedom by using the DtN artifi-cial boundary condition.The artificial boundary is usually selected as a circle or spherical surface to solve various types of fields,such as sound waves or electromagnetic waves,provided that the considered domain is infinite or unbounded in all directions.However,the substantial wave motion is considered in water of finite depth,that is,the fluid domain is bounded vertically but unbounded horizon-tally.Thus,the DtN boundary condition is given on an artificial cylindrical surface,which divides the water domain into an interior and exterior region.The boundary integral equation is adopted to implement the present model.In the case of a floating cylinder,the results of hydrodynamic coefficients of a chamfer box are discussed.

Simulation of a Novel Schottky Body-Contacted Structure Suppressing Floating Body Effect in Partially-Depleted SOI nMOSFET's

A novel Schottky body-contacted structure for partially depleted SOI nMOSFET's is presented.This structure can be realized by forming a shallow n +-p junction and two sidewall spacers in the source region,and then growing a thick silicide film,which can punch through the shallow junction and make a Schottky contact to the p-type silicon.Simulation results show that the anomalous subthreshold slope and kink effects are suppressed successfully and the drain breakdown voltage is improved considerably.This method has the same device area and is completely compatible with the bulk MOSFET process.

Floating Body Effect in Partially Depleted SOI nMOSFET with Asymmetric Structure and Ge-Implantation

The floating body effect of an asymmetric and Ge implanted partially depleted 0 8μm SOI nMOSFET is investigated.It is found that the drain breakdown voltage can be improved by about 1V and that the anomalous subthreshold slope and kink effect are also lessened.It is believed that the shallow junction in the source and defect states introduced by Ge implantation are responsible for the reduction of the floating body effect.

Influence of Floating Body Effect on Radiation Hardness of PD SOI nMOSFETs

H-gate and closed-gate PD SOI nMOSFETs are fabricated on SIMOX substrate,and the influence of floating body effect on the radiation hardness is studied.All the subthreshold characteristics of the devices do not change much after radiation of the total dose of 106rad(Si).The back gate threshold voltage shift of closed-gate is about 33% less than that of H-gate device.The reason should be that the body potential of the closed-gate device is raised due to impact ionization,and an electric field is produced across the BOX.The floating body effect can improve the radiation hardness of the back gate transistor.

Wave Radiation and Diffraction by A Two-Dimensional Floating Body with An Opening Near A Side Wall

The radiation and diffraction problem of a two-dimensional rectangular body with an opening floating on a semi- infinite fluid domain of finite water depth is analysed based on the linearized velocity potential theory through an analytical solution procedure. The expressions for potentials are obtained by the method of variation separation, in which the unknown coefficients are determined by the boundary condition and matching requirement on the interface. The effects of the position of the hole and the gap between the body and side wall on hydrodynamic characteristics are investigated. Some resonance is observed like piston motion in a moon pool and sloshing in a closed tank because of the existence of restricted fluid domains.

Experimental Study of Nonlinear Behaviors of A Free-Floating Body in Waves

Nonlinear behaviors of a free-floating body in waves were experimentally investigated in the present study. The experiments were carried out for 6 different wave heights and 6 different wave periods to cover a relatively wide range of wave nonlinearities. A charge-coupled device （CCD） camera was used to capture the real-time motion of the floating body. The measurement data show that the sway, heave and roll motions of the floating body are all harmonic oscillations while the equilibrium position of the sway motion drifts in the wave direction. The drift speed is proportional to wave steepness when the size of the floating body is comparable to the wavelength, while it is proportional to the square of wave steepness when the floating body is relatively small. In addition, the drift motion leads to a slightly longer oscillation period of the floating body than the wave period of nonlinear wave and the discrepancy increases with the increment of wave steepness.

Side Wall Effects on the Hydrodynamics of a Floating Body by ImageGreen Function Based on TEBEM

A novel numerical model based on the image Green function and first-order Taylor expansion boundary element method(TEBEM), which can improve the accuracy of the hydrodynamic simulation for the non-smooth body, was developed to calculate the side wall effects on first-order motion responses and second-order drift loads upon offshore structures in the wave tank. This model was confirmed by comparing it to the results from experiments on hydrodynamic coefficients, namely the first-order motion response and second-order drift load upon a hemisphere, prolate spheroid, and box-shaped barge in the wave tank. Then,the hydrodynamics of the KVLCC2 model were also calculated in two wave tanks with different widths. It was concluded that this model can predict the hydrodynamics for offshore structures effectively, and the side wall has a significant impact on the firstorder quantities and second-order drift loads, which satisfied the resonant rule.

Mechanism of floating body effect mitigation via cutting off source injection in a fully-depleted silicon-on-insulator technology

In this paper, the effect of floating body effect （FBE） on a single event transient generation mechanism in fully depleted （FD） silicon-on-insulator （SOI） technology is investigated using three-dimensional technology computer-aided design （3D- TCAD） numerical simulation. The results indicate that the main SET generation mechanism is not carder drift/diffusion but floating body effect （FBE） whether for positive or negative channel metal oxide semiconductor （PMOS or NMOS）. Two stacking layout designs mitigating FBE are investigated as well, and the results indicate that the in-line stacking （IS） layout can mitigate FBE completely and is area penalty saving compared with the conventional stacking layout.

Numerical Investigation of Heave and Pitch Motion Effects on Green Water Loading for a Floating Body

In this paper,the influence of heave and pitch motions on green water impact on the deck is numerically investigated.The vessel motions are determined using a potential theory based method and provided as input to finite volume based CFD computations of green water phenomenon.A dynamic mesh approach is adopted to determine instantaneous body positioning in the fluid domain.Detailed validation studies with published experimental results for 2D and 3D fixed vessel cases are initially performed to validate the present numerical approach before studying the moving vessel problem.The results show that inclusion of heave and pitch motion changes the disturbed wave field near the bow which influences the free surface as well as the impact loading due to green water.The effect of wave steepness on green water impact is also investigated and it is seen that the present numerical method is capable of capturing green water load.It is observed that the effects of vessel motions on green water load are not negligible and one should consider this effect too.The incorporation of vessel motions in the vertical plane affects the green water loading on the deck.

Mathematical Modelling of Response Amplitude Operator for Roll Motion of a Floating Body：Analysis in Frequency Domain with Numerical Validation

This paper investigates mathematical modelling of response amplitude operator （RAO） or transfer function using the frequency-based analysis for uncoupled roll motion of a floating body under the influence of small amplitude regular waves. The hydrodynamic coefficients are computed using strip theory formulation by integrating over the length of the floating body. Considering sinusoidal wave with frequency （ω ） varying between 0.3 rad/s and 1.2 rad/s acts on beam to the floating body for zero forward speed, analytical expressions of RAO in frequency domain is obtained. Using the normalization procedure and frequency based analysis, group based classifications are obtained and accordingly governing equations are formulated for each case. After applying the fourth order Runge-Kutta method numerical solutions are obtained and relative importance of the hydrodynamic coefficients is analyzed. To illustrate the roll amplitude effects numerical experiments have been carried out for a Panamax container ship under the action of sinusoidal wave with a fixed wave height. The effect of viscous damping on RAO is evaluated and the model is validated using convergence, consistency and stability analysis. This modelling approach could be useful to model floating body dynamics for higher degrees of freedom and to validate the result.

THE SUDDEN STARTING OF A FLOATING BODY IN DEEP WATER

This paper applies Lagrangian method to discuss the sudden starting of a floating hotly in deep water and the analytical'solutions are obtained. It is known from the numerical results that the disturbing domain extends and the dynamic pressure also increases when the breadth of the floating body keeps constant and its depth increases.

FREE-SURFACE WAVES AND FAR WAKES GENERATED BY A FLOATING BODY IN A VISCOUS FLUID

The free-surface waves and the flow field due to a body moving on the surfaceof an incompressible viscous fluid of infinite depth were studied analytically. The floating bodywas modeled as a normal point pressure on the free surface. Based on the Oseen approximation forgoverning equations and the linearity assumption for boundary conditions, the exact solutions inintegral form for the free-surface elevation, the velocities and the pressure were given. Byemploying Lighthill's two-stage scheme, the asymptotic representations in far field for largeReynolds numbers were derived explicitly. The effect of viscosity on the wave profiles was expressedby an exponential decay factor, which removes the singular behavior predicted by the potentialtheory.

Body-contact self-bias effect in partially depleted SOI-CMOS and alternatives to suppress floating body effect

As SOI-CMOS technology nodes reach the tens ofnanometer regime, body-contacts become more and more ineffective to suppress the floating body effect. In this paper, self-bias effect as the cause for this failure is analyzed and discussed in depth with respect to different structures and conditions. Other alternative approaches to suppressing the floating body effect are also introduced and discussed.

Time-domain simulation for water wave radiation by floating structures (Part A)

Direct time-domain simulation of floating structures has advantages:it can calculate wave pressure fields and forces directly; and it is useful for coupled analysis of floating structures with a mooring system. A time-domain boundary integral equation method is presented to simulate three-dimensional water wave radiation problems. A stable form of the integration free-surface boundary condition (IFBC) is used to update velocity potentials on the free surface. A multi-transmitting formula (MTF) method with an artificial speed is introduced to the artificial radiation boundary (ARB). The method was applied to simulate a semi-spherical liquefied natural gas (LNG) carrier and a semi-submersible undergoing specified harmonic motion. Numerical parameters such as the form of the ARB, and the time and space discretization related to this method are discussed. It was found that a good agreement can be obtained when artificial speed is between 0.6 and 1.6 times the phase velocity of water waves in the MTF method. A simulation can be done for a long period of time by this method without problems of instability, and the method is also accurate and computationally efficient.

Wave Drift Forces on Two Floating Bodies Arranged Side by Side

An innovative hydrodynamic theory and numerical model were developed to help improve the efficiency, accuracy, and convergence of the numerical prediction of wave drift forces on two side-by-side deepwater floating bodies. The wave drift forces were expressed by the double integration of source strength and the corresponding Green function on the body surface, which is consistent with the far field formula based on momentum conservation and sharing the advantage of near field calculations providing the drift force on each body. Numerical results were validated through comparing the general far field model and pressure integral model, as well as the middle field model developed usin^z the software HydroStar.

Gate-to-body tunneling current model for silicon-on-insulator MOSFETs

A gate-to-body tunneling current model for silicon-on-insulator （SOl） devices is simulated. As verified by the mea- sured data, the model, considering both gate voltage and drain voltage dependence as well as image force-induced barrier low effect, provides a better prediction of the tunneling current and gate-induced floating body effect than the BSIMSOI4 model. A delayed gate-induced floating body effect is also predicted by the model.

半潜船波浪诱导运动与载荷预报数值方法比较研究

Numerical simulation tools based on potential-flow theory and/or Morison’s equation are widely used for predicting the hydrodynamic responses of floating offshore wind platforms.In general,these simplified approaches are used for the analysis under operational conditions,albeit with a carefully selected approach to account for viscous effects.Nevertheless,due to the limit hydrodynamic modelling to linear and weakly nonlinear models,these approaches severely underpredict the low-frequency nonlinear wave loads and dynamic responses of a semisubmersible.They may not capture important nonlinearities in severe sea states.For the prediction of wave-induced motions and loads on a semisubmersible,this work systematically compares a fully nonlinear viscous-flow solver and a hybrid model combining the potential-flow theory with Morison-drag loads in steep waves.Results show that when nonlinear phenomena are not dominant,the results obtained by the hybrid model and the high-fidelity method show reasonable agreement,while larger discrepancies occur for highly nonlinear regular waves.Specifically,regular waves with various steepness over different frequencies are focused in the present study,which supplements the understanding in applicability of these two groups of method.

A Novel LDMOS Structure in Thin Film Patterned-SOI Technology with a Silicon Window Beneath p Well

A novel patterned-SOI LDMOS structure with a silicon window beneath the p well is proposed.The performance is simulated numerically.In comparison to SOI counterpart,the off-state and the on-state breakdown voltage can increase by 57% and 70% respectively;transconductance is flatter;I-V curves take no sign of kink in the saturation region;the device temperature is much lower even at high input power;the floating body effect and the self-heating effect are distinctly suppressed.Furthermore,the advantage of low leakage current and low output capacitance in SOI structures does not degrade.The proposed structure will be a promising choice to improve the performance and reliability of SOI power device.

Experimental Investigation on the Hydrodynamic Performance of A Wave Energy Converter

Wave energy is an important type of marine renewable energy. A wave energy converter （WEC） moored with two floating bodies was developed in the present study. To analyze the dynamic performance of the WEC, an experimental device was designed and tested in a tank. The experiment focused on the factors which impact the motion and energy conversion performance of the WEC. Dynamic performance was evaluated by the relative displacements and velocities of the oscillator and carrier which served as the floating bodies of WEC. Four factors were tested, i.e. wave height, wave period, power take-off （PTO） damping, and mass ratio （RM） of the oscillator and carrier. Experimental results show that these factors greatly affect the energy conversion performance, especially when the wave period matches RM and PTO damping. According to the results, we conclude that： （a） the maximization of the relative displacements and velocities leads to the maximization of the energy conversion efficiency; （b） the larger the wave height, the higher the energy conversion efficiency will be; （c） the relationships of energy conversion efficiency with wave period, PTO damping, and RM are nonlinear, but the maximum efficiency is obtained when these three factors are optimally matched. Experimental results demonstrated that the energy conversion efficiency reached the peak at 28.62% when the wave height was 120 mm, wave period was 1.0 s, RM was 0.21, and the PTO damping was corresponding to the resistance of 100 Ω.

A SPH simulation on large-amplitude sloshing for fluids in a two-dimensional tank

Smoothed particle hydrodynamics（SPH） is a mesh-free adaptive Lagrangian particle method with attractive features for dealing with the free surface flow.This paper applies the SPH method to simulate the large-amplitude lateral sloshing both with and without a floating body,and the vertical parametrically-excited sloshing in a two-dimensional tank.The numerical results show that the SPH approach has an obvious advantage over conventional mesh-based methods in handling nonlinear sloshing problems such as violent fluid-solid interaction,and flow separation and wave-breaking on the free fluid surface.The SPH method provides a new alternative and an effective way to solve these special strong nonlinear sloshing problems.