Speed Plane Research Articles

Steatosis, inflammation, fibroprogression, and cirrhosis in remnant liver post-liver donation.

This is a cross-sectional observational study conducted on living liver donors focusing on "long-term remnant liver health" specifically looking at steatosis, inflammation, and fibrosis using multiparametric ultra sonological evaluation and noninvasive blood tests. Multiparametric ultrasound evaluation included assessment of shear wave elastography (fibrosis), sound speed plane wave ultrasound, attenuation plane wave ultrasound (steatosis), and viscosity plane wave ultrasound (inflammation). Blood test based APRI and FIB-4 were calculated. Liver biopsy was performed if noninvasive evaluation pointed toward clinically relevant fibro progression (F4). Out of 36 donors, significant fibrosis (>F2) was found in 11 donors (30.5%), seven donors (19.4%) had severe fibrosis (>F3), and two donors had shear wave elastography values suggestive of cirrhosis(F4). Of these two, one donor was extensively evaluated and was found to have biopsy proven cirrhosis with endoscopic evidence of portal hypertension. The prevalence of fatty liver disease in our study group was 50%. We report the first liver donor cohort with fibroprogression and cirrhosis occurring in the remnant liver. Our donor cohort with a significant proportion having steatosis and fibroprogression underscores the importance of regular follow-up of liver donors and evaluation of remnant liver.

Coronal Signatures of Flare Generated Fast-Mode Wave at EUV and Radio Wavelengths

This paper presents a detailed study of the type II solar radio burst that occurred on 06 March 2014 using combined data analysis. It is a classical radio event consisting of type III radio burst and a following type II radio burst in the dynamic spectrum. The type II radio burst is observed between 235 – 130 MHz (120 – 60 MHz) in harmonic (fundamental) bands with the life time of 5 minutes between 09:26 – 09:31 UT. The estimated speed of type II burst by applying two-fold Saito model is ∼ 650 km s−1. An extreme ultraviolet (EUV) wave is observed with Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). The very close temporal onset association of the EUV wave and flare energy release indicates that the EUV wave is likely produced by a flare pressure pulse. The eruption is also accompanied by a weak coronal mass ejection (CME) observed with the coronagraphs onboard the Solar and Heliospheric Observatory (SOHO) and the twin Solar Terrestrial Relations Observatory (STEREO). The plane of sky speed of the CME was ∼ 252 km s−1 in the SOHO/LASCO-C2 and ∼ 280 km s−1 in the STEREO-B/SECCHI-COR1 images. The EUV wave has two wave fronts, one expanding radially outward and the other one moving along the flare loop arcade. The source position of the type II burst imaged by the Nançay Radio Heliograph (NRH) shows that it was associated with the outward moving EUV wave. The CME is independent of the shock wave as confirmed by the location of NRH radio sources below the CME’s leading edge. Therefore the type II radio burst is probably ignited by the flare. This study shows the possibility of EUV wave and coronal shock triggered by flare pressure pulse, generating the observed type II radio burst.

Analysis of Surface and Interior Permanent Magnet Motor Topologies for Active Electromagnetic Damping Applications

Many modern high-end vehicles exploit controllable damping solutions to enhance their adaptability to different road conditions and driving styles. Among these technologies, active dampers offer improved performance due to their four-quadrant operation in the torque–speed plane. In active electromagnetic dampers, brushless permanent magnet machines are used because of their high torque density. However, to the best of our knowledge, a process to set the previously reported; likewise, which rotor topology exhibits the best performance in such cases has not been validated. Consequently, the resulting actuator could exhibit suboptimal dynamical performance and power conversion efficiency. Although some design processes have been formulated in the past for semiactive controllers (the damping is modified using a variable resistive load), they are not suitable for active suspension control. Similarly, there are existing solutions to increase conversion efficiency using mechanical motion rectifiers; however, active forces cannot be exerted, limiting their applicability to semiactive actuators. Therefore, this paper presents a design methodology, using finite element method together with MATLAB/Simulink™, to set and test the parameters of AC brushless PM machines, intended for actively controlled suspensions. A novel approach to set the base speed, which takes advantage of field-weakening capability, is also presented. To test the proposed method, three machines with well-known rotor topologies were designed and evaluated as case studies, and the surface-mounted topology was found to be the most suitable for the analyzed task.

Bead morphology of laser welded steel sheets and its correlation to the joint’s electrical and mechanical properties

Nowadays, lasers are routine tools in the widest range of materials processing, including welding of battery packs. The properties of the laser generated weld bead are crucial in determining the electrical and mechanical behavior of the joint. Here, we report on the identification of five morphological bead types, namely, Rosenthal, single wave, elongated, pre-humping, and humping morphologies and their systematic appearance over the laser power versus scanning speed plane. We prove that each type exhibits characteristic electrical and mechanical behavior that differ not only in the magnitude of relevant materials’ properties, but also in their variability. We show for nickel-coated steel and uncoated DC01 cold rolled steel that the so-called single wave morphology is best suited for battery welding applications, since this morphology class concomitantly exhibits the lowest electrical resistance and the highest mechanical strength, both with a relatively small margin of error. The results suggest that the bead morphology could be exploited as a simple indicator of joint properties.

Minimal wave speed for a population model with density-dependent migrations and the Allee effect

In this paper, we study the minimal wave speed for a class of population models with density-dependent migration speed and the Allee effect. We first give the exact expression for the minimal wave speed for the case of linear migration speed. This in turn specifies a critical curve in the parameter plane of the migration speed and the Allee effect which separates a region of the linear determinacy of the minimal wave speed from a region of the nonlinear determinacy of the minimal wave speed. Next, for a class of nonlinear migration speed, the corresponding minimal wave speed is shown to enjoy similar qualitative properties as depicted in the case of linear migration speed.

Full Operational Envelope Control of a Wind Turbine Using Model Predictive Control

This study presents a full operational envelope controller for a full nonlinear 5 MW Supergen exemplar wind turbine based on multivariable model predictive control (MPC). Below the rated wind speed, the primary objective of the controller is to maximize the energy capture. Above the rated wind speed, the controller maintains the rated power. The controller switches between control modes according to the prevailing wind speed to maintain control over the full envelope of operating regions. A linearized model is derived from a model of an exemplar 5 MW Supergen wind turbine in state-space form. The linearized model is then used to realize a feedback MPC (FB-MPC) and feedforward MPC (FF-MPC) to consider the lack and incorporation, respectively, of wind speed information. The switching strategy is tracked on the torque–speed plane. Simulations are performed at multiple wind speeds to evaluate the robustness and switching performances of the designed controllers by applying them to a full nonlinear 5 MW Matlab/SIMULINK model of the same exemplar Supergen wind turbine. Improved tracking is achieved over the full envelope with FF-MPC rather than FB-MPC. Simulation results are presented in the time and frequency domain in addition to the torque–speed plane demonstrating that the control performance is improved without an increase in the control activity (i.e., pitch action) of the turbine; that is, the controller’s gain crossover frequency remains within the acceptable range, around 1 rad/s. Note that most work presented in the literature focus on specific wind speeds only; that is, either only below rated wind speed or above rated wind speed. In contrast, the controllers reported here cover the full envelope of operation regions, making this work more practical and novel.

Decoupling the Monitoring of Solar Water Heaters and their Usage Profiles

South Africa is the most technologically advanced nation in Africa. However, the country is plagued with constant load shedding. The country receives about 2500 sunshine hours annually, with daily average irradiation levels of 4.5–6.5 kWh/m2. Despite these potentials, the use of electricity for domestic water heating is still prevalent in the country. The mass rollout of solar water heating (SWH) technologies in the low-cost housing sector across the country were met with massive failures. This study aims to assess the energy yield of a passive flat plate and an evacuated tube solar water heating system by evaluating the performance of these systems to address the energy crisis in South Africa. The flat plate (FP) and evacuated tube (ET) solar water heating systems were monitored for four days, characterised by varying sky conditions through instantaneous data measurement at 5 s. The parameters measured were water temperature, ambient temperature, irradiance at the plane of array, relative humidity, wind speed and direction. The results obtained show that a maximum irradiance of 1050 W/m2 was obtained on a clear day and corresponded to a hot water temperature of about 58 °C and 65 °C for the FP and ET, respectively. However, a cloudy day with a maximum irradiance of 400 W/m2 produced about 22 °C and 29 °C of hot water for the FP and ET, respectively. The results obtained in this study will guide stakeholders in the renewable energy sector towards employing SWH systems to replace or augment the electric geyser. Solar water heaters (SWH) can be used in the low-cost housing sector to provide hot water. Hence, the assessments in this study offer essential information for the deployment of these systems to reduce demand on the ailing South African electricity utility, Eskom, and mitigate climate change.

Effects of non-Fourier heat conduction and surface heating rate on thermoelastic waves in semi-infinite ceramics subject to thermal shock

Non-Fourier heat conduction has been observed in many fast heating experiments. This paper studies the thermoelastic fields of semi-infinite ceramics subjected to surface heating shock based on non-Fourier C–V model, which may have its root application for future thermal protection system of space vehicles. To simulate the surface heating process, a family of exponential functions is presented. Furthermore, the ratio of heating duration to thermal relaxation time, and the ratio of thermal wave speed to elastic wave speed are introduced to study the coupling effects of heating rate, non-Fourier heat conduction and inertia. Firstly, the time horizon and spatial scale where the non-Fourier effect is significant has been delimited. Secondly, it is demonstrated that the thermal stress component along depth increases and converges as the depth increasing. Thirdly, the domain where the maximum thermal stresses influenced by non-Fourier heat conduction are drawn by the critical lines in the plane of dimensionless heating duration vs thermoelastic wave speed. This study may be useful for designs of ceramic heat insulations.

Effect of waterjet intake plane shape on course-keeping stability of a planing boat

Abstract The course-keeping stability of a high speed planing boat should be considered at the design stage for its safe operations. The shape of waterjet intake plane is one of important design parameters of a waterjet propelled planing boat. That has significant influences on the stern flow patterns and pressure distributions. In this study, the effects of the waterjet intake shapes of planing boats on the course-keeping stabilities are investigated. Two kinds of designed planing boats have the same dimensions, but there are differences in waterjet intake plane shapes. Captive and free-running model tests, Computational Fluid Dynamics (CFD) analyses are carried out in order to estimate their hydrodynamic performances including course-keeping stabilities. The results show that the flat and wide waterjet intake plane of the initially designed boat makes the course-keeping stability worse. The waterjet intake shape is re-designed to improve the course-keeping stability. The improved performances are confirmed by free-running model tests and full-scale trials.

The hull-waterjet interaction of a planing trimaran

Hull-waterjet interaction is a key point in the research of waterjet-propelled crafts. The previous researches on hull-waterjet interaction mainly aim at displacement ships and planing monohulls, and mostly focus on speeds of FrL < 1.5, which has not included maximum speed of waterjet-propelled crafts in current engineering practice. Based on numerical and experimental research, this paper studies the hull-waterjet interaction of a high speed planing trimaran in the speed range of 0.68 < Fr▽<6.16 (0.32<FrL < 2.87), including analysis of thrust deduction and interaction efficiency. The numerical simulation is based on the Reynolds-Averaged Navier-Stokes (RANS) equation with the SST k-ω turbulence model. As for semi-planing and planing state of this planing trimaran, the local effect of waterjet suction and jet is helpful to reduce the resistance while the global hull-attitude change will cause the increment on resistance of self-propelled hull. Compared with monohulls, the negative resistance increment fraction of this trimaran occurs at higher speed. The jet system thrust deduction fraction is always negative at high speeds and increases almost linearly with speed growth. The interaction efficiency is larger than 1.0 when Fr▽>2.0, indicating that the hull-waterjet interaction of this trimaran has positive effects on propulsion performance at semi-planing and planing state.

Chatter Detection in Milling of Carbon Fiber-Reinforced Composites by Improved Hilbert-Huang Transform and Recurrence Quantification Analysis.

In the paper, the problem of chatter vibration detection in the milling process of carbon fiber-reinforced plastic is investigated. Chatter analysis may be considered theoretically based on data from impact test of an end mill cutter. However, a stability region obtained in such way may not agree with the real one. Therefore, this paper presents a method that can predict chatter vibrations based on cutting force components measurements. At the beginning, a stability lobe diagram is created to establish the range of experimental test in the plane of tool rotational speed and depth of cut. Next, an experiment of composite milling is performed. The experimentally-measured time series of cutting forces are decomposed with the use of the improved Hilbert–Huang transform (HHT). To detect chatter, statistical methods and recurrence quantification analysis (RQA) are used. However, much better results are obtained when new chatter indexes are proposed. The indexes, derived directly from the HHT and RQA methods, can be used to build an effective chatter prediction system.

Search for missing links between two extreme wind speed profiles: dark energy accretion and adiabatic fluid accretion

In the recent past, progress in accretion studies onto general relativistically gravitating central objects viz. a Schwarzschild singularity reveals that the accretion flow should be transonic. Regarding such cases, radial inward speed gradient might be written as a numerator over denominator form among which the denominator vanishes somewhere in between infinite distance to the event horizon of the attractor. For sustainability of a physical solution, the numerator should also have to be equal to zero at the same radial distance where the denominator does vanish. From this point, using L’Hospital’s rule, we obtain a second degree first order differential equation of radial inward speed. Hence, using the initial conditions at the said radial distance, we obtain two branches of flow by the virtue of two first order differential equations. These branches are named as accretion and wind. For adiabatic accretion case, the slope of the wind curve in speed vs radial distance plane is formed to be more or less parallel to the radial distance axis as we move far from the central object. For dark energy accretion, alignment of this curve is parallel to the radial velocity axis. Here we face a question why there is no fluid speed profile in between these two extremities. While searching for the reasons, we follow that dark energy, if treated as an accreting object, should stay around the central compact star and hence will contaminate the metric which properties the compact star. In this research work, we have proposed a model with a rotating black hole embedded in quintessence where quintessence equation of state and spin parameter of the black hole are together working as the regulatory factors of the model. The resulting accretion and wind curves are studied. The Effect of negative pressure of dark energy is found to get catalyzed by the entry of the spin of the black hole. We tally our results with observations of accretion or outflow phenomenon near to different quasars.

An Organic Rankine Cycle Bottoming a Diesel Engine Powered Passenger Car

Organic Rankine Cycle (ORC) power plants are characterized by high efficiency and flexibility, as a result of a high degree of maturity. These systems are particularly suited for recovering energy from low temperature heat sources, such as exhaust heat from other plants. Despite ORCs having been assumed to be appropriate for stationary power plants, since their layout, size and weight constraints are less stringent, they represent a possible solution for improving the efficiency of propulsion systems for road transportation. The present paper investigates an ORC system recovering heat from the exhaust gases of an internal combustion engine. A passenger car with a Diesel engine was tested over a Real Driving Emission (RDE) cycle. During the test exhaust gas mass flow rate and temperature have been measured, thus calculating the enthalpy stream content available as heat addition to ORC plant in actual driving conditions. Engine operating conditions during the test were discretized with a 10-point grid in the engine torque–speed plane. The ten discretized conditions were employed to evaluate the ORC power and the consequent engine efficiency increase in real driving conditions for the actual Rankine cycle. N-pentane (R601) was identified as the working fluid for ORC and R134a was employed as reference fluid for comparison purposes. The achievable power from the ORC system was calculated to be between 0.2 and 1.3 kW, with 13% system efficiency. The engine efficiency increment ranged from 2.0% to 7.5%, with an average efficiency increment of 4.6% over the RDE test.

광폭 고속 활주선 선형개발에 관한 연구

In this study, a high speed planing boat with 7.2 meters in length is developed as the beam larger about 10% by comparing with the general planing boat. The design speed of a boat is 30 knots (about 15.4 m/s) by using 150 hp outboard engine and the main material is FRP. The resistance performance related to the free running attitude as trim and sinkage is discussed and the wave patterns are observed to clear the relationship between the performance and wave characteristics by model test. The turning circle is estimated by Lewandowski´s equation. The results show that not only the wave pattern but also the free running attitude of the boat have the strong influence on a resistance performance. The boat needs smaller engine power and has more stable running attitude because of large sinkage and small variation of trim due to the large area for the lift force and light weight.

On hydrodynamic analysis of stepped planing crafts

Using transverse steps is one of the adopted strategies to improve the hydrodynamic characteristics of planing crafts. In the present paper, hydrodynamic characteristics of stepped planing crafts are numerically investigated. For this purpose, we analyzed the effects of five different types of transverse steps on lift to drag ratio, resistance, trim angle and sinkage of high speed planing crafts. Contours of pressure distribution on the bottom of crafts, water volume fraction and free-surface are also presented at different hull velocities. Computed numerical results are properly validated against our conducted towing tank experimental tests.

전산유체계산을 통한 고속 활주선의 저항성능 및 유동분포 해석

전산유체계산을 통한 고속 활주선의 저항성능 및 유동분포 해석

Numerical investigation of the porpoising motion of a seaplane planing on water with high speeds

During the taking-off and landing processes on water, a seaplane will begin to porpoise under a certain set of conditions, which is a threat to the flying safety. Porpoising motion is an unstable oscillation about the gravity center in the vertical direction. In this paper, the porpoising phenomenon is studied by a modified two-phase flow solver in OpenFOAM through the simulation of a large seaplane with four turbines during take-off. In order to study the porposing motion under real conditions, complex effects are fully considered such as the hydrodynamic forces, aerodynamic forces, ground effect and slipstream. Firstly, an actuator disk method is added to the interDyMFoam solver, and the sixDoFRigidBodyMotion solver is also modified to make the actuator disk move together with the aircraft. By doing this, the efficiency of computation is greatly improved in the unsteady multi-phase calculation. Secondly, verification and validation (V&V) studies are carried out by comparing the results herein to those of the benchmark towing tank experiments of Fridsma and a single propeller wind tunnel test. Stable high speed planing is studied in advance, and the triggering conditions and dynamic characteristics of porpoising are investigated subsequently. The free surface together with pressure and velocity fields are analyzed and discussed in detail. The result shows that slipstream offers a nose down pitching moment, which increases the aerodynamic lift significantly, and the center of hydrodynamic force moves to the front of gravity center, leading to the continuous amplification of the unstable oscillation in porpoising. As a result the heaving and pitching oscillations are mainly determined by hydrodynamic force, while the aerodynamic force only plays an auxiliary role.

Sensorless passivity based control for induction motor via an adaptive observer

The work of this paper addresses the study and application of control strategies based on the passivity of a sensorless induction motor (IM) in order to guarantee a high performance operation and to increase reliability at a lower cost. This control approach based on the passivity or the energy formulation is generally simple and physically meaningful. It achieves the control objective by reshaping the system natural energy and then injecting a damping term. A full-order adaptive observer is also considered to estimate the IM rotor flux and mechanical speed. These estimated quantities are then used in the control scheme. The observer gain is synthesized in the way that it minimizes the instability zone in the regenerative mode to a line in the torque–speed plane. The control-observer set is tested on the trajectories of the various operating modes (motor mode, regenerating mode and low speed mode).

Design Optimization of a High Torque Density Spoke-Type PM Motor for a Formula E Race Drive Cycle

Performance trade offs for achieving high torque density and high drive-cycle efficiency in spoke-type permanent magnet (PM) motors are investigated. Unlike the traditional method, which relies on analytical equations, this trade-off study is conducted through a statistical analysis of the Pareto-optimal design candidates resulting from a large-scale design optimization of an example traction machine over a Le Mans-based drive cycle. In the design optimization process, both low-speed and extended-speed/field-weakening operating regions are evaluated using high-fidelity electromagnetic finite element (FE) simulations with an objective to simultaneously increase the torque density and decrease the power losses over the high energy-throughput-zones of the machine torque–speed plane. The resultant 3400 design candidates are utilized to investigate the impact of increasing power density on other important performance metrics such as power losses, PM demagnetization, and torque ripple. This analysis is supplemented by multiphysics simulation of three counterpart optimized designs and successful experimental verification of a prototype of one of those three designs which represents a record high power density motor in traction applications.

Statistical Analysis of Wedge Effect on the Seakeeping of a Planing Hull in Irregular Waves at the Onset of the Planing Region

In the current paper, different experiments are conducted on a high speed planing craft in irregular waves, with and without a wedge. Performance and seakeeping aspects of these planing hulls in the form of trim, rise-up, and resistance in regular waves and heave, pitch, bow, and center of gravity (CG) acceleration in irregular waves are extracted in time series. Irregular waves represent sea state 3 with 12cm height and peak period of 1.66. A model length of 2.63m and 1:5 scale is considered and all data for irregular waves are scaled, as well. The deadrise angle is constant and is taken to be 24 degrees. The targeted experimental tests are conducted for four longitudinal Froude numbers of 1.0, 1.18, 1.37, and 1.57, which are all in the planing regime. The results are analyzed for the mean height of wave, significant wave height, RMS, and spectrum. The comprehensive study of wedges' effects is also presented which indicates that a wedge can decrease the motions and accelerations, exceedingly. Ultimately, the obtained results are compared against those by Fridsma (1971) and Soletic (2010) and it is demonstrated that motions and accelerations are indeed reduced.