Drift Area Research Articles

Drift analysis and prediction of debris from Malaysia Airlines flight MH370

Malaysia Airlines flight MH370 disappeared on 8 March 2014, while flying from Kuala Lumpur, Malaysia, to Beijing, China. The Malaysian Prime Minister concluded that “flight MH370 ended in the southern Indian Ocean” on 24 March 2014. A piece of marine debris, later confirmed to be a flaperon from flight MH370 by the French prosecutor, was found on Reunion Island in the western Indian Ocean on 29 July, 2015. In the present study, the aircraft debris are assumed to drift in the surface layer and the vertical movement is not taken into account. Based on the surface drifting buoys and maritime objects drift prediction model, the drifting trajectories and time scales of the debris are estimated. It was found that 100 drift buoys passed in the possible air crash waters and eleven of them finally reached Reunion according to analysis of surface drift buoys in Indian Ocean. Among these, two buoys drifted northwestward took about 500 days, close to the debris drift time, testified the possibility that debris from the possible air crash waters could drift to Reunion, from the point of observational facts. The Leeway factors were reparameterized and the wave effect was ignored. The OSCAR reanalysis currents and CFSR reanalysis winds in southern Indian Ocean were processed as forcing field. Then a maritime objects drift prediction model for the southern Indian Ocean was established based on Leeway maritime drift theory. Three scenarios experiments with different initial time (5 d apart) were designed. 1024 objects were placed in the possible air crash waters to enhance statistical significance. Each experiment was divided to three conditions with different leeway factors of 0.012, 0.015 and 0.018. The experiments were carried out to compute the drift trajectory of 9216 objects in total initially placed in the possible air crash waters from March 2014 to July 2015 for 500 d. The results show that the trajectories of the objects are basically the same with the surface drift buoys, indicating the robust performance of the drift prediction model. 53, 48 and 47 objects are found in Reunion Island area for the three experiments, with the probability of 17‰, 16‰ and 15‰. Three kinds of trajectory are concluded for the objects in Reunion Island area at the end of the prediction. The first kind is drifting northeastward then northwestward then westward; the second kind is drifting northward then westward; the third kind is drifting northwestward. The probabilities of objects arrive in the Reunion Island area with different leeway factors of 0.012, 0.015 and 0.018 are 7‰, 13‰ and 28‰. The probability increases along with the leeway factor. The possible reason is that during the drift area, the wind is mainly southeast trade wind. Due to the long integration time, position difference of every time step accumulates, eventually causing the large distance of different leeway factors. The possible air crash waters and currently search area estimated by relevant departments are correct, indirectly verified by this research.

Comprehensive behavioral model of dual-gate high voltage JFET and pinch resistor

Many analog technologies operate in large voltage range and therefore include at least one or more high voltage devices built from low doped layers. Such devices exhibit effects not covered by standard compact models, namely pinching (depletion) effects, in high voltage FETs often called quasisaturation. For example, the conventional compact JFET model is insufficient and oversimplified. Its scalability is controlled by the area factor, which only multiplies currents and capacitances but does not take into account existing 3-D effects. Also the optional second independent gate is missing. Therefore, the customized four terminal (4T) model written in Verilog-A (FitzPatrick and Miller, 2007; Sagdeo, 2007) was developed. It converges very well, its simulation speed is comparable with conventional compact models, and contains all required phenomena, including parasitic effects as, for example, impact ionization. This model has universal usage for many types of devices in various high voltage technologies such as stand-alone voltage dependent resistor, pinch resistor, drift area of power FET, part of special high side or start-up devices, and dual-gate JFET.

Optimization of a MOS–IGBT–SCR ESD protection component in smart power SOI technology

A MOS–IGBT–SCR component that was proposed in a previous paper to increase the device robustness and the cost of ESD protection circuit is optimized in this paper. In order to improve its latch-up immunity, several variations of geometrical parameters that have been simulated using TCAD Sentaurus Device in another previous paper have been implemented and compared in this work. The drift area, the form factor, and the proportion of P+ sections inserted into the drain are the main parameters, which have a significant impact on the latch-up immunity. TLP characterization, and curve tracer measurements have been carried out to evaluate the proposed solution. Holding current increases up to 70mA and holding voltage up to 10V.

Terrestrial exposure and effects of Headline AMP(®) Fungicide on amphibians.

Recent studies have demonstrated that a pyraclostrobin-containing fungicide (Headline(®) Fungicide--Headline(®) Fungicide and Headline AMP(®) Fungicide are registered trademarks of BASF) is toxic to amphibians at environmentally relevant concentrations. However, these studies were performed in a laboratory setting of a worst-case direct exposure in clean media. Interception of spray by the crop canopy and ground cover used by animals for security cover will influence exposure. Thus, risk to amphibians is unclear in an environmentally realistic field environment. We tested exposure and toxicity of Headline AMP(®) Fungicide to amphibians in multiple agricultural habitat scenarios (e.g., within treated crop vs. grassy areas adjacent to crop) and at two rates during routine aerial application. Specifically, we placed Woodhouse's toads (Bufo woodhousii) and Blanchard's cricket frogs (Acris blanchardi) in enclosures located within treated and untreated corn (VT stage, approximate height = 3 m), and in the potential drift area (adjacent to treated corn) during aerial application of Headline AMP Fungicide at either 731 or 1052 ml/ha (70 and 100 % the maximum application rate in corn, respectively). Mean concentrations of pyraclostrobin measured at ground level were ≤19 % of nominal application rate in all areas. Overall, mean mortality of recovered individuals of both species was ≤15 %, and mortality within Headline AMP Fungicide-treated corn (where risk was anticipated to be highest) was <10 %. It is important to understand that application timing, interception by the crop canopy (which varies both within and between crop systems), and timing of amphibian presence in the crop field influences risk of exposure and effects; however, our results demonstrate that amphibians inhabiting VT stage corn during routine aerial application of Headline AMP Fungicide are at low risk for acute mortality, matching existing laboratory results from acute toxicity studies of Headline Fungicide.

Wake effects on drift in two-dimensional inviscid incompressible flows

This investigation analyzes the effect of vortex wakes on the Lagrangian displacement of particles induced by the passage of an obstacle in a two-dimensional incompressible and inviscid fluid. In addition to the trajectories of individual particles, we also study their drift and the corresponding total drift areas in the Föppl and Kirchhoff potential flow models. Our findings, which are obtained numerically and in some regimes are also supported by asymptotic analysis, are compared to the wakeless potential flow which serves as a reference. We show that in the presence of the Föppl vortex wake, some of the particles follow more complicated trajectories featuring a second loop. The appearance of an additional stagnation point in the Föppl flow is identified as a source of this effect. It is also demonstrated that, while the total drift area increases with the size of the wake for large vortex strengths, it is actually decreased for small circulation values. On the other hand, the Kirchhoff flow model is shown to have an unbounded total drift area. By providing a systematic account of the wake effects on the drift, the results of this study will allow for more accurate modeling of hydrodynamic stirring.

A 30 W 800 MHz complimentary LDMOS power amplifier for wireless application

This work presents the design of an optimized power amplifier using Complementary LDMOS (CLDMOS) with 5μm gate length. Final results show that the high performance CLDMOS amplifier has been achieved using the optimization of various device parameters and the circuit bias conditions. Optimization of the drift length and the drift area doping in device parameters have been done for both P type LDMOS (PLDMOS) and N type LDMOS (NLDMOS) for various Analog/RF applications. And these optimizations yields CLDMOS power amplifier with 36dB gain, 800MHz bandwidth and 46.4% efficiency. Comparing with existing structure a good improvement of gain and bandwidth has been observed.

&lt;b&gt; Temporal distribution of ichthyoplankton in the Forquilha river, upper Uruguay river – Brazil: Relationship with environmental factors &lt;/b&gt; - doi: 10.4025/actascibiolsci.v36i1.17993

This study aimed to evaluate the temporal distribution of fish eggs and larvae in the Forquilha river (upper Uruguay river/Brazil) and its relationship with environmental variables. Ichthyoplankton and abiotic factors were sampled from September 2006 to August 2007. At the laboratory, samples were sorted and larvae were identified to the lowest possible taxonomic level. For data analysis we applied One-way Anova, Tukey’s test, Pearson correlation and PCA. In this study 200 eggs and 308 larvae were collected, showing differences in the temporal distribution and influence of abiotic factors. Larvae were identified in all stages of development, being distributed in three order and eight families. These results point that the lower portion of the Forquilha river is an important drift and nursery area for fish larvae of the upper Uruguay river. The breeding season for most species was greatly marked, between October and January, coinciding with the increase in temperature and decrease of the water flow. The response of reproductive intensity varies according to the environmental variables.

Estimation Theory on Cross-Sectional Area of Cables in Mega Steel Frame and Cable Bracing Structure

The mega steel frame and cable bracing structure belongs to the pre-stressed high-rising building and how to estimate cross-sectional area of cables is one of key problems for this new structural system. Considering shear and bending deformation, the relationship between structural story drift and cross-sectional area of cables is established by using the superposition principle of deformation. Further, cross-sectional area of cables is determined based on the design target value of story drift that is known. The qualitative estimation method on cross-sectional area of cables is finally developed. The cross-sectional area obtained by using this method is its lower critical value, and the method presented is useful for the preliminary design and qualitative evaluation.

Estimation Theory on Cable’s Diameter in Pre-Stressed Mega Brace and Steel Frame Structure

According to the superposition principle of building structure, the lateral deformation mode of pre-stressed mega bracing-steel frame structure was analyzed, then the relation between the structural maximum inter-story drift and cross section area of cable was further established. Based on the area of cable derived by the design target value of inter-story drift, the qualitative estimation theory on cross section area of the cable is finally determined.

Quantifying complexity and variability in phase portraits of gait

Background Injuries to the lower extremity often cause limitations to joint motion and alter movement patterns of limb segments during gait. We hypothesized that complexity and variability of limb segment motion during gait would increase in both limbs due to unilateral injury. Using simulated injury to generate asymmetric gait, we developed new methods to quantify changes in the complexity and variability of limb segment angular phase portraits. Methods To simulate reduced range of motion associated with knee injury, the right knee was constrained to full extension by an external brace. Thigh, shank and foot segment angular phase portraits were generated from 20 healthy male subjects walking for 3-minute trials with and without the brace. Using Fourier-based methods, complexity was quantified by the number of harmonic frequencies suitable for fitting the phase-portrait shape — with a larger number of harmonics indicating greater complexity. Variability was characterized by the drift and confidence area generated by the inter-cycle excursion of the phase-portrait centroid. Findings Significant differences were found in complexity and variability measures due to bracing. Phase-portrait shape complexity and variability increased in the right (braced) limb, compared to the unbraced condition; while only variability increased for the left (contralateral) limb during bracing. Interpretation These new methods proved successful at quantifying changes in the complexity and variability that have been visually observed in phase portraits during asymmetric gait. This work provides a method that can be incorporated into clinical assessments to provide quantifiable measures of more precise differences in gait dynamics.

Dense-phase velocity fluctuation in a 2-D fluidized bed

Abstract This work presents an investigation of the perturbations induced by the bubbles in a 2-D fluidized bed. A combination of Digital Image Analysis (DIA) and Particle Image Velocimetry (PIV) techniques was developed to characterize the dense and bubble phases. The analysis of the mean and the instantaneous fluctuations of the velocity of the dense phase, together with the solid movement around bubbles, allowed for the measurement of the influence region, distinguishing an upward moving dense phase in the nose and the wake of the bubble (drift) and a downward moving dense phase in the sides of the bubble. For an isolated bubble, we measured the drift area within the total influence region and related the size of these regions to the equivalent diameter of the bubble. This work also presents results on the volumetric dissipation of kinetic energy, where we concluded that the energy dissipation in the dense phase is proportional to the square of the bubble velocity.

Spatial and temporal distribution patterns of ichthyoplankton in a region affected by water regulation by dams

The aim of this work was to study the occurrence of ichthyoplankton in a region affected by water regulation by dams. The study area was located in the region of Ilha Grande National Park, upper Paraná River floodplain. Specifically, we examined the temporal and spatial distribution of Ichthyoplankton, identified spawning areas and established the relationships between the abundances of fish eggs and larvae and some limnological and hydrological variables. Samples were taken monthly between October and March from 2001 to 2005 at 24 sampling sites. For analytical purposes, the sampling sites were grouped into upper, middle and lower areas. The upper area of the National Park had the highest egg density and should be considered the primary spawning area. The middle area should be considered a drift area, and the lower area likely functions as a growth and feeding habitat. Statistical analyses showed that the spawning was influenced by water temperature, pH, fluviometric level and rainfall, and that larval density was influenced by pH, conductivity, dissolved oxygen and rainfall. The results also revealed that the tributaries apparently are used as migratory routes by fish, and and this shows the need to protect these sites.

Predicting the effect of tilling practices on wind erosion activity: application of the Wind Erosion Prediction System in a sand drift area in The Netherlands

AbstractThe inland drift sand area in The Netherlands forms a unique ecosystem in northern Europe, but is characterized by a rapid decline in both aeolian activity and area size. It is therefore necessary to investigate how the drift sand areas can be preserved, and how their immobilization by vegetation can be counteracted by introducing techniques that reactivate the aeolian processes. Four such techniques (rotary cultivator, beach sand cleaner, disc harrow and excavator) were evaluated during an 8‐month experiment at Kootwijkerzand, The Netherlands. The effectiveness of the techniques to reactivate the aeolian processes was measured by investigating their effect on the horizontal sediment flux. Furthermore, the Wind Erosion Prediction System was used to simulate the effect of the different techniques, without the noise related to field measurements. Both field experiment and model simulation showed that the most effective method is the beach sand cleaner, followed by the rotary cultivator. Unlike measurement in the field, the model did not simulate any mass transport on the plot tilled with the excavator. Here incoming sediment could have initiated mass transport. In the case of the plot tilled with the disc harrow the model overestimated the transport. In reality, however, a surface layer with a high random roughness shows large variation in moisture content in space and time resulting in lower mass transport. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Computer simulation of corona discharge in an inert gas

In this document, computation of the corona discharge in a “cylinder-cylinder” electrode system is described. The Fokker-Planck equation is used to describe the kinetics of the electrons. The basic features of the physical process were observed in the solution. It shows that the stationary mode is possible only when the voltage is larger than a definite threshold value. One can discern two character areas between the electrodes. The internal area where the ionization is active and the current is carried both by electrons and ions has radius of 100–200 micrometers. The rest of the accommodation constitutes the drift area. The solution enables one to compare the illuminating zone and the zone of electrons multiplication. It revealed some features of rare gas discharge that preclude from directly applying the results of this work to discharge in air. Above all, it is a small value of negative charge density, which is caused by the electron conduction character in the external area. Nevertheless the solution of this model problem displays the wide possibilities of the method.

Theoretical research on the performance of a practical helix travelling wave tube

On the basis of a rigorous field theory, two different physical models of attenuator and sever have been proposed. One is named High attenuation (HATT) model in which both attenuator and sever are considered as a unified attenuator, but the sever is regarded as an area of very high loss; the other is called Sever and attenuator (SATT) model in which the sever is modelled as a drift area in which the electric and magnetic fields both vanish. A complex function is derived and potential sinking effect is also considered. Thus, a set of more practical self-consistent equations of nonlinear beam-wave interaction is formulated. Simulations are carried out under the conditions of the two different physical models, and the simulation results are compared with the experimental data. The results show that in the case of single signal drive, the unknown second harmonic should be included for predicting the saturated output power. It is also evident that the SATT model and the HATT model predict the same physical nature, whereas the results predicted by the HATT model are much closer to the experimental data than those obtained from the SATT model. Therefore, these results provide a strong theoretical basis for designing broadband and high gain helix travelling wave tubes.

Morphological evidence of species differentiation within Lepus capensis Linnaeus, 1758 (Leporidae, Lagomorpha) in Cape Province, South Africa

A morphological study was carried out of the hares ( Lepus) from Cape Province previously assigned to the subspecies L. capensis capensis, L. c. centralis, and L. c. grantii. The purpose of the study was to characterize the species L. capensis Linnaeus, 1758. In doing so, it was possible to distinguish two populations which we consider different species, as each shows homogeneous cranial, dental and pelage features. One of them, defined as L. capensis, is distributed near Cape Town not far from the coast, between Lambert's Bay and Cape Agulhas. The other species, defined as L. centralis, which includes L. grantii as a synonym , is distributed in central and western Cape Province. L. capensis and L. centralis have a parapatric distribution, with a small area of sympatry in a contact zone in Compagnies Drift area, near Lambert's Bay. With respect to cranial differences between the two species, L. capensis has a stronger maxilla and more robust dental series, while L. centralis has larger tympanic bullae. Among dental characters, L. centralis usually has a deeper groove and more abundant cement than L. capensis in the first upper incisor, and its internal lobe is squared, while in L. capensis is rounded. As for pelage color and pattern, L. capensis shows a more extended white ventral area than L. centralis. Our results are of interest for further research on taxonomic problems regarding Old World hare populations in which L. capensis is concerned.

Drift in supported membranes

An object moving in a fluid transports the fluid along the direction of its motion. Using the concept of drift, i.e., the net motion of a small volume of fluid or a tracer particle due to a moving body, we quantify this entrainment for an inclusion in a supported lipid bilayer membrane. Our analysis demonstrates that a moving object in a supported membrane transports a small volume of fluid by a significant distance only when the initial position of the fluid volume in question is within a distance ξ from the line of motion, where ξ is the screening length of the membrane. The total area swept out by a line of such fluid volume elements, initially at rest and oriented perpendicular to the direction of motion, is the drift area. We show that the drift area is related quadratically to the screening length. These calculations suggest that dynamic domains of entrained lipids of size ξ form spontaneously around moving objects in supported membranes due to hydrodynamic interactions. This effect is potentially important for transport processes in biological and artificial membranes.

A pulsed system for powering the magnetic coils of an ion diode with external magnetic insulation

A pulsed power system of magnetic coils of an ion diode with external magnetic insulation (IDM), which ensures operation of the diode in the frequency mode, is described. Demands are formulated for the IDM magnetic field in which the electronic cloud acting as a cathode in the diode is formed and for storage conditions of the negative charge in the magnetic field for neutralizing the ion beam in the ion-beam drift area. Basic relationships required for engineering calculations of the IDM coils and a pulsed power system in the frequency mode are given.

Dune Landscape Rejuvenation by Intended Destabilisation in the Amsterdam Water Supply Dunes

In the Dutch coastal dunes, several projects have started in which aeolian activity is stimulated to enhance landscape rejuvenation by increasing aeolian erosion and deposition. The aim of these projects is to reverse vegetation succession and create opportunities for pioneer stages. In 1995, a drinking water extraction canal in the Amsterdam Water Supply Dunes was closed and the original landscape was restored. Since then, the development of the area was left to natural processes. This resulted in large-scale deflation structures and the development of sand drift areas. By means of air photographs, the changes in the landscape were studied. Initially, the sand drift area expanded, up to a maximum of 11 ha in 1999. In the following years, stabilisation of the surface by vegetation became more and more important. After 8 years of undisturbed development, half of the bare surface was still bare, and the active area was still 2.5 times larger than the stabilised area. But bare spots were scattered over the area, and the average size per spot decreased from 10 ha in 1995 to <1 ha in 2003. The percentage of surface covered by pioneer species was large (5 ha in 2003) and might result in increased stabilisation rates in future. Part of the stabilisation could be explained by meteorological conditions during the studied period. Part could be explained because the system is supply limited. Scale might be an important issue in the final success of remobilisation, as indicated by preliminary comparison to larger-scaled projects. Further comparisons are needed. After eight years, it is still too early to say whether large-scale destabilisation measures in the case of artificially fixed coastal dunes result in durable aeolian activity and landscape rejuvenation. However, even if the area will be stabilised within the next years, the landscape has many impulses for new ecological development. For the next decade, we need to continue our monitoring programs; meanwhile, experimentation with methods of reactivation should be conducted.

Evaluation of the soil penetration resistance along a transect to determine the loosening depth

The objective of this study was to evaluate the distribution of soil strength (measured as cone index, CI) along a 600 m transect and to determine the soil loosening depth necessary to eliminate zones with soil strengths exceeding a threshold value down to a depth of 0.6 m. The transect was located at a site in a glacial drift area which was characterised by sandy deposits overlying boulder clay. A tractor-mounted multi-penetrometer array consisting of four hydraulically driven single vertical penetrometers was used to determine CI at 1-m sampling intervals as a measure of penetration resistance. The spatial fluctuation of the CI readings in general and that of repeatedly averaged readings along the transect was examined. Furthermore, the relationships between the penetration resistance of several soil layers and the relationships between the CI of single penetrometers were identified. Averaged CI values over 5-m intervals were used to determine the depth of soil loosening required. By using various data sub-sets based on the averaged data of the four array mounted penetrometers and simulating several different sampling intervals, treatment intervals and threshold values of soil strength, a sampling interval of about 10 m proved to be sufficiently accurate to determine the loosening depth required.