Top PDF On the 3-D reconstruction of Coronal Mass Ejections using coronagraph data

On the 3-D reconstruction of Coronal Mass Ejections using coronagraph data

On the 3-D reconstruction of Coronal Mass Ejections using coronagraph data

CMEs are typically observed in white light images provided by space-based coronagraphs such as LASCO (Brueckner et al., 1995) and ground-based instruments such as the MK III and MK IV coronagraphs at Mauna Loa. Coro- nagraphs provide us with a two-dimensional representation of the CME three-dimensional structure projected onto the plane of the sky (POS). As a consequence, the measured quantities like angular width, height, speed as well as de- rived quantities like mass and energy of CMEs are also pro- jected on this plane and therefore, represent lower limits of the true, un-projected CME properties. The projection ef- fects on these quantities can be estimated by making assump- tions about the CME propagation direction and shape, but the true 3-D properties of the CME remain difficult to estimate reliably (Vrˇsnak et al., 2007). The new data from the So- lar TErrestrial RElations Observatory (STEREO) (Kaiser et al., 2008), which was launched in October 2006, provides us with stereoscopic images of the Sun’s atmosphere. The two STEREO spacecraft orbit the Sun at approximately 1 AU near the ecliptic plane with a separation angle between them increasing at a rate of about 45 degrees/year. The first satel- lite orbits Ahead of the Earth in it’s orbit around the Sun, and the second Behind (labeled A and B, respectively, hereon). The stereoscopic images obtained by the Sun Earth Connec- tion Coronal and Heliospheric Investigation (SECCHI) in- strument suite (Howard et al., 2008) aboard STEREO allow us to make 3-D estimations of the structure and kinematic parameters of CMEs.
Mostrar mais

13 Ler mais

Predictions of the arrival time of Coronal Mass Ejections at 1AU: an analysis of the causes of errors

Predictions of the arrival time of Coronal Mass Ejections at 1AU: an analysis of the causes of errors

The drag force will tend to equalise the speed of the ICME and solar wind, and clearly this is important in determining the observed speed of ICMEs at 1 AU. However, the flux rope nature of many ICMEs (e.g. magnetic clouds) implies that in some topologies there can be a significant outward Lorentz force (e.g. Chen, 1996). Thus, one should look for a corre- lation between early arrival and the average ICME magnetic field strength. In addition, as we shall discuss in Sect. 4.4, information about how 1τ depends on the field strength can yield clues to which part of an ICME one is encountering. In both cases, one would expect stronger fields to be associ- ated with earlier arrivals. The result of such a study using the VG2002 model is shown in Fig. 5. There is a weak trend towards early arrival for stronger field strengths (the late ICMEs have an average magnetic field strength of 10.2 nT, while early ones have an average field of 14.8 nT). However, it should be noted that even using extremes of the distribu- tion (i.e. the means of |B| for ejecta with 1τ = ±0.3 days), we could only discount the null hypothesis with an 80% con- fidence.
Mostrar mais

11 Ler mais

ERNE observations of energetic particles associated with Earth-directed coronal mass ejections in April and May, 1997

ERNE observations of energetic particles associated with Earth-directed coronal mass ejections in April and May, 1997

Abstract. Two Earth-directed coronal mass ejections (CMEs), which were most e€ective in energetic (1± 50 MeV) particle acceleration during the ®rst 18 months since the Solar and Heliospheric Observatory (SOHO) launch, occurred on April 7 and May 12, 1997. In the analysis of these events we have deconvoluted the injection spectrum of energetic protons by using the method described by Anttila et al. In order to apply the method developed earlier for data of a rotating satellite (Geostationary Operational Environmental Sat- ellites, GOES), we ®rst had to develop a method to calculate the omnidirectional energetic particle intensi- ties from the observations of Energetic and Relativistic Nuclei and Electrons (ERNE), which is an energetic particle detector onboard the three-axis stabilized SOHO spacecraft. The omnidirectional intensities are calculated by ®tting an exponential pitch angle distri- bution from directional information of energetic pro- tons observed by ERNE. The results of the analysis show that, compared to a much faster and more intensive CMEs observed during the previous solar maximum, the acceleration eciency decreases fast when the shock propagates outward from the Sun. The particles injected at distances <0.5 AU from the Sun dominate the particle ¯ux during the whole period, when the shock propagates to the site of the spacecraft. The main portion of particles injected by the shock during its propagation further outward from the Sun are trapped around the shock, and are seen as an intensity increase at the time of the shock passage.
Mostrar mais

9 Ler mais

Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere &ndash; application to CME-CME interaction

Deriving the radial distances of wide coronal mass ejections from elongation measurements in the heliosphere &ndash; application to CME-CME interaction

et al., 2009), by mass conservation principles (Colaninno and Vourlidas, 2009), or by applying one of two simple approxi- mations giving an analytical relation between elongation an- gles and CME positions (Wood et al., 2009; Rouillard et al., 2009; Davis et al., 2009). These analytical relations provide a quick and easy way to estimate CME dynamics in the he- liosphere. 3-D reconstruction and forward modeling are ex- pected to be more accurate than these simple relations, espe- cially in the COR FOV where they have been mostly used so far, but they also have some limitations. For example, the 3-D reconstruction methods require multiple viewpoints, which might become less and less frequent as the STEREO space- craft separate; when there are multiple observations, they as- sume that both SECCHI instruments observe the same struc- ture, which is not true in the HI FOV. Additionally, forward modeling attempts to fit geometrical and kinematic informa- tion at the same time. To simplify the fit, a kinematic model (often constant acceleration or constant speed) is usually as- sumed. As noted above, these assumptions cannot be used for complex events, such as those involving CME-CME in- teractions.
Mostrar mais

10 Ler mais

Optimum Design Of On Grid Pv System Using Tracking System

Optimum Design Of On Grid Pv System Using Tracking System

The research showed that PV system is a promising project since PV panel cost is continuing decrease in cost. This research considered comparison among PV systems (Fixed – Manual – One axis – Two axis) using on grid tracking system for producing 110 KWp. The criterion used in this research to determine the optimum solution is the cost of produced one kilo watt hour. However, it is shown that two axis automatic tracking system produces maximum energy. But PV fixed panels system is Optimum economically among PV systems, where it is less expensive to produce energy and more profitable. If exceeded energy is sold to Egyptian government (according to new laws approved by Egyptian government), according to governmental facilities approved, it is allowed borrow up to 70% of the initial cost of the project. Economic analysis showed that borrowing at 4% interest gives minimum system cost. The profit in this case return on this project is expected to be 19.8 % and also in this system total cost to produce 1 KWh is about 0.73 EGP/ KWh, It is less the cost price of production 1 KWh by conventional methods.
Mostrar mais

8 Ler mais

Radiol Bras  vol.49 número3

Radiol Bras vol.49 número3

(Bayer Pharma AG; Leverkusen, Germany), at a concentration of 769 mg/mL. The injection was applied with an injector pump (Envision CT; Medrad, Indianola, PA, USA) with a flow rate of 5 mL/s, and the dosage was approximately 1.5 mL/kg (maximum total dose of 150 mL). Only the post-contrast arterial phase was used for the sample cases. The axial sec- tions (1 mm thick) were acquired at a pitch of 0.8, a recon- struction thickness of 2 mm, and a standard 250 mm field- of-view. During the arterial phase, image acquisition was started with a 6-s delay, after the threshold of 100 Hounsfield units had been reached at the region of interest within the abdominal aorta. The acquisition parameters used for the arterial phase in the abdominal protocol were similar to those used for CTA tests and showed sufficient spatial and tempo- ral resolution to characterize the arterial vessels studied in this paper. The images were processed in a Philips Extended Brilliance workstation using a viewer program. Finally, we used the MPR (2D), MIP and VR (3D) methods to acquire images in the axial, coronal, and sagittal planes.
Mostrar mais

6 Ler mais

Volume distribution for particles between 3.5 to 2000 μm in the upper 200 m region of the South Pacific Gyre

Volume distribution for particles between 3.5 to 2000 μm in the upper 200 m region of the South Pacific Gyre

increased with depth and was the highest in the DCM. Al- gae in the DCM were mainly picophytoeukaryotes, although some coccolithophorid plates and diatom cells were also present (Beaufort et al., 2007; G´omez et al., 2007; Ras et al., 2007). The small particle did not show any peak in the DCM probably because the minimum size used to calculate the size spectra (3.5 µm) is larger than the dominant phy- toplanktonic cells. The large particles had only one max- imum in the DCM that was found in all profiles suggest- ing that the particles at 100 m depth were not a source of aggregates but that the active picophytoeukaryotes, coccol- ithophorid plates and diatom cells found in the DCM could be. The aggregates that form the material observed by the UVP could also be detritus produced by zooplankton be- cause the Phaeophorbide pigment (a tracer for altered Chl-a found in faecal pellets) concentration also had a maximum in this layer (Ras et al., 2007). The large particles could not have been living mesozooplankton (d>200 µm) because an- imal concentrations in the upper 200 m depth averaged less than 0.1 ind. L −1 (personal data) compared to the large par- ticles estimates of 20 part. L −1 . In the MAR site, concentra- tion of microphytoplankton (10<d<100 µm, mostly small pennate diatoms of the genus Pseudonitzschia) ranged from 1000 to 32 000 cells L −1 (G´omez unpublished data). These concentrations are in the same range as the HIAC counts for particles d>10 µm (5500+/−250 cells L −1 ). Therefore, many of the particles larger than 10 µm detected by the HIAC in the MAR site were probably diatom cells. Aggre- gates of Pseudo-nitzschia delicatisisima and large Rhizosole- nia bergonii were observed from 50 to 100 m depth with con- centrations of 2 to 20 aggregates L −1 and constituted some of the particles larger than d>100 µm. Again, mesozooplank- ton were not an important fraction of the large particles be- cause their concentrations in the upper 200 m layer were less than 1 ind. L −1 (personal data), compared to UVP particle concentrations as great as 100 part L −1 .
Mostrar mais

12 Ler mais

The influence of the arc plasma treatment on the structure and microhardness C120U carbon tool steel

The influence of the arc plasma treatment on the structure and microhardness C120U carbon tool steel

Surface of C120 steel after arc plasma treatment showed tracks have multizone microstructure composed of the remelted zone, heat affected zone and substrate, which can have diversified microhardness. Structure (particularly precipitation of martensite, bainite retained austenite and secondary cementite) in the remelted zone is dependent on the arc plasma treatment parameters. The cooling rate obtained during the treatment by arc plasma of the steels is compared to the cooling rate of the steels during conventional heat treatment. This cooling rate can be estimated on the basis of the standard CCT diagram for C120 steel. Increased of the current intensity of arc plasma lead to of grater areas of materials remelting and it decreases of the cooling
Mostrar mais

4 Ler mais

Rev. Bras. Cir. Plást.  vol.27 número3

Rev. Bras. Cir. Plást. vol.27 número3

Two (8%) laps were completely lost due to massive fat necrosis and skin ulcerations that developed after irradia tion of the reconstructed breast and required the implementa tion of an additional reconstructive surgica l procedure in which the latissimus dorsi lap was combined with the implant. Two

4 Ler mais

Winning the Oil Lottery: The Impact of Natural Resource Extraction on Growth Tiago Cavalcanti Daniel Da Mata Frederik Toscani

Winning the Oil Lottery: The Impact of Natural Resource Extraction on Growth Tiago Cavalcanti Daniel Da Mata Frederik Toscani

Enhanced recovery is so important in the petroleum industry that the location of the producer well is chosen with the secondary well (injection well) in mind. As mentioned before, efforts to enhance recovery are costly and are dependent upon the state of the economy and the potential oil recovery volume. Consequently, repeated monitoring of a reservoir is essential to choose the best locations for the injection wells. The idea is to design an optimal distribution of injection wells so as to optimize long-term production. There are several types of wells: wildcat well, rank wildcat well, step-out well, pro- ducer well, injection well, etc. Since there are different steps in the process of obtaining oil, wells are classified broadly as exploratory wells and development wells. Examples of exploratory wells are wildcat wells (drilled a mile or more from an area of existing oil production) and rank wildcat wells (drilled in an area where there is no existing produc- tion). If the exploratory drilling proves successful, the company starts to drill step-out wells (also included in the exploratory well category). After the oil field has been delin- eated, the company starts to drill production wells within the known extent of the field. Every well drilled inside the known extent of the field is called a development well (Hyne (2001)). The development well category includes producer wells and injection wells (re- call that injection wells are drilled to enhance oil recovery). Different categories of wells have different probabilities of finding oil. On average, rank wildcat exploratory wells have lower success ratio than step-out wells. An oil company can rank wells in terms of probability, even in the face of uncertainty. The American Petroleum Institute reported that in 2000 the success rate for wildcat wells was 39% (Hyne (2001)). Note that an unsuccessful drilling is classified as a dry hole in both exploratory and development well categories.
Mostrar mais

50 Ler mais

Identification of boundary heat flux on the continuous casting surface

Identification of boundary heat flux on the continuous casting surface

In the paper the numerical solution of the inverse problem consisting in the identification of the heat flux on the continuous casting surface is presented. The additional information results from the measured surface or interior temperature histories. In particular the sequential function specification method using future time steps is applied. On the stage of numerical computations the 1st scheme of the boundary element method for parabolic equations is used. Because the problem is strongly non-linear the additional procedure 'linearizing' the task discussed is introduced. This procedure is called the artificial heat source method. In the final part of the paper the examples of computations are shown.
Mostrar mais

6 Ler mais

Inference of admixture and population size changes in structured populations with applications to conservation genetics

Inference of admixture and population size changes in structured populations with applications to conservation genetics

that may affect the results is that the models do not take into account the fact that the hybrid, the parental and/or the ancestral populations could be structured, and exchanging genes with other non sampled populations. While this is an issue shared with all inference methods published to date (e.g. Hey and Nielsen 2004; Excoffier et al. 2005; Sousa et al. 2009), this is still a potential problem that should be kept in mind when interpreting results from real data. The advantage of an ABC approach is that it is possible to test its robustness to such departures. Also, an ABC method could be implemented and tested to perform inference under such complex models. The third caveat is related with the specification of the prior distributions, which is a general problem in Bayesian statistics. This is a critical point as has been recently shown by Beaumont (2008) and Guillemaud et al. (2009). For instance, Guillemaud et al. (2009) showed that it is possible that a dataset fits a population split model with a very recent split, but if we specify prior distributions favoring old split times the method can fail to identify the population split as the most likely model, identifying another, incorrect model as the most likely. This is an important point because different models may appear as more or less likely depending on the range of the parameter values and the weight given to different parameter values, as defined by the priors. One possible solution is to use wide non-informative prior distributions. It is expected that by increasing the number of loci the dependence on prior distributions will decrease (Beaumont and Rannala 2004), and that repeating the analysis with different sets priors its effects can be quantified. Actually, the analysis of the data from I. lusitanicum has been done with two different prior sets to test for this effect. Although both cases favored the population split without admixture model (Figure 4), the distance analysis (Figure 5) showed that one of the prior sets could not fit the observed data. Again, more work is required on this general issue.
Mostrar mais

209 Ler mais

Int. braz j urol.  vol.37 número1

Int. braz j urol. vol.37 número1

Figure 3 – A coronal reconstruction shows debries and an ad- herent ileal loop outlined by the gas-illed bladder. A transplant kidney is seen on the left side, with only minimal stranding in the perirenal space. However edema is seen peripelvic and peri- ureteral space.

2 Ler mais

J. bras. pneumol.  vol.43 número4

J. bras. pneumol. vol.43 número4

after sustaining a chest injury in an automobile accident. An air leak persisted for 5 days after the surgery. On the ifteenth postoperative day, the patient was referred to our emergency ward due to respiratory dificulty. Examination conirmed that he was experiencing mild respiratory dificulty; RR was 25 breaths/min and HR was 98 bpm. Examination of the respiratory system revealed subcutaneous emphysema and the absence of pulmonary sounds in the right hemithorax. A chest X-ray showed right hydropneumothorax. A multislice CT scan conirmed this inding, and multiplanar reconstruction demonstrated the presence of a bronchopleural istula in
Mostrar mais

1 Ler mais

Effect of heat treatment parameters on the properties of low-alloy cast steel with microadditions of vanadium

Effect of heat treatment parameters on the properties of low-alloy cast steel with microadditions of vanadium

This article examines the effect of prolonged time of holding at the temperature of 620 0 C on the processes of secondary phase precipitation and mechanical properties of low-alloy cast steel with an addition of vanadium subjected to two variants of heat treatment, i.e. U:1150 0 C+H:950 0 C+O:620 0 C and H:950 0 C+O:620 0 C. To determine an impact of the applied heat treatment operations, testing of mechanical properties and microstructural examinations of the cast steel with 0,21 and 0,27%C were carried out.
Mostrar mais

4 Ler mais

COMBINATIONS OF CHOLECALCIFEROL AND 25-HYDROXYCHOLECALCIFEROL AS VITAMIN D SOURCES IN WHITE LAYING HEN FEED DIETS

COMBINATIONS OF CHOLECALCIFEROL AND 25-HYDROXYCHOLECALCIFEROL AS VITAMIN D SOURCES IN WHITE LAYING HEN FEED DIETS

The effect of cholecalciferol (D 3 ) and 25-hydroxycholecalciferol (25-OHD 3 ) as isolated or associated sources of vitamin D (100%-0%, 75%-25%, 50%-50%, 25%-75%, 0%-100%) on the productive performance, egg quality, and bone characteristics was evaluated in white egg-laying hens fed two levels of calcium (Ca) and phosphorus (P) in the basal diet (BD) (BD1 = 0.38% Ca – 0.36% available P and BD2 = 3.2% Ca – 0.30% available P). Nine hundred and sixty Dekalb White hens (24 weeks old) were distributed into 80 cages, under a completely randomized factorial design for 16 weeks. The use of associated sources of vitamin D reduced the feed intake and feed conversion ratio, as well as BD1, which also increased the egg production and egg mass. The association of vitamin D sources with up to 50% 25-OHD 3 increased the eggshell percentage. There was interaction (p<0.05) between the sources of vitamin D and the concentrations of Ca and available P, sources with at least 50% 25-OHD 3 increased ash percentage and bone radiographic densitometry (BRD) with BD1; in BD2 the use of 25-OHD 3 as isolated vitamin D source increased BRD. The association of D 3 and 25-OHD 3 improved the productive performance, increased the percentage of eggshell and had different positive effects on the bone characteristics that depend on the concentrations of Ca and available P in the balanced feed of white egg-laying hens.
Mostrar mais

8 Ler mais

Braz. j. .  vol.82 número5

Braz. j. . vol.82 número5

radiotherapy of the nasopharynx and cervical lymph nodes (total dose = 70 Gy) was completed. After one month, mild swelling in the right medial canthal area was noted. Visual acuity, intraocular pressure, and ocular motility were within normal limits and there was no exophthalmos. Orbit CT

4 Ler mais

Report on the reconstruction of Managua

Report on the reconstruction of Managua

Fernando Valle LSpez, he offered the services of consultants for preparation of the functional program and preliminary designs of the General Managua Hospital, the School of Nursing and [r]

6 Ler mais

Crucial views on the German Reunification of 3 Octomber 1990

Crucial views on the German Reunification of 3 Octomber 1990

Kohl shows much feeling by describing the period of childhood and youth. One can read about parents and school, family and friends. Moreover he even focuses on his first wife Hannelore whom he dedicated this volume. Author narrates how he and his wife gave their first son the name Walter. Thus, he became his name after Kohl's own brother who perished during World War II and his mother's brother, who was fallen in the First World War. The tears that were thereafter in the eyes of his mother are among the most deeply rooted experiences of those generations. Therefore, by all his will to power and assertiveness, Kohl's political coordinates and limits were marked also by such sad family stories. He was belonged to that generation, which no longer needed serve as a soldier, but witnessed very consciously the Second World War and its horrors. Another track of his personality was the coinage as a Pfälzer on the frontier with France. Therefore, he developed a patriotic but no way nationalistic understanding of homeland and nation. Here he also learned a lot about the idea of Europe that fitted perfectly into his political interests and guiding principles. These sections are belonging to the most touching passages of the book.
Mostrar mais

65 Ler mais

The Impact of E-Commerce Securi ty, and National Environment  on Consumer adoption of Intern et Banking in Malaysia and  Singapore

The Impact of E-Commerce Securi ty, and National Environment on Consumer adoption of Intern et Banking in Malaysia and Singapore

Relative advantage is defined as the extent to which a person views an innovation as offering an advantage over previous ways of performing the same task (Roger, 1983; Agarwal & Prasad, 1997). Because Internet banking services allow customers to access their banking account from any location 24 hours a day and 7 days a week, it provides an enormous advantage and convenience to users (Tan & Teo, 2000). It also gives customers greater control over managing their finances, as they are able to check their accounts easily. Besides, a customer’s Internet experience, his or her banking needs can affect his adoption. As there are more financial products and services, it is expected that individuals with many financial accounts and who subscribe to many banking services will be more inclined to adopt Internet banking. Tan and Teo (2000) has reported that potential adopters of Internet banking services are likely to own multiple banking accounts and subscribe to various banking services. Rogers argues that potential adapters, who are allowed to experiment with an innovation will feel more comfortable with the innovation and are more likely to adopt it. Thus, if customers have the opportunity to try the innovation, certain fears of the unknown may be minimized. Government policy could also aid or hinder Internet diffusion (Mbarika, 2002). This is consistent with the national systems of innovation theory that posits that government policies may encourage or mandate technology development and adoption (King et. al., 1994; Wolcott et. al., 2001). Tan and Teo (2000) suggest that the greater the extent of government support for Internet commerce, the more likely Internet banking will be adopted, thus, confirming Goh’s (1995) suggestion that governments can play an interventionist and leading role in the diffusion of innovation. Potential users in turn would view new applications such as Internet banking services more favorably and hence be more like to use them. Thus, the second alternative hypothesis is:
Mostrar mais

20 Ler mais

Show all 10000 documents...

temas relacionados