HV Component Research Articles

Using the Pauli Scattering Mechanisms for Analysis of Polarimetric SAR Images from RADARSAT Constellation and TanDEM-X Missions

This work describes techniques for extraction of information in polarimetric images from RADARSAT constellation mission (RCM) and TanDEM-X (TDX) and TerraSAR-X (TSX) satellites. Using the boundary conditions of Maxwell's equations it is shown how the single bounce and double bounce scattering can be extracted from quad-pol and compact polarimetric (CP) SAR. We develop new equations to calculate the Pauli decomposition from simulated CP data using RCM quad-pol data. The RCM CP option is circular transmit, linear receive (CTLR). We find that using quad-pol data performs better than using CP data for Pauli decomposition, especially extraction of the HV component. Estimation of single bounce and double bounce scattering from RCM CP data is feasible and yields more information about scattering properties than the CP components alone. We show how more information can be extracted from bistatic TSX/TDX quad-pol data by estimation of the coherence of the different Pauli components and optimization of the interferometric coherence using ships as detection objects. This is a unique opportunity to use optimized coherence on moving ships for characterizing their structure.

The cross-scattering component of polarimetric SAR in urban areas and its application to model-based scattering decomposition

ABSTRACTAfter the work of Freeman, Durden, Pottier, and Yamaguchi, many decomposition techniques have been proposed for urban areas, mainly to resolve the overestimation problem of volume scattering. Since it has been validated that the cross-polarized (HV) scattering is caused not only by forests but also by rotated dihedrals, in this paper, we propose a cross-scattering coherency matrix to model the HV component from orientated and complex buildings and then demonstrate its performance on model-based scattering decomposition. The building orientation angle is considered in this coherency matrix, making it flexible and adaptive in the decomposition. Therefore, the HV components from forests and orientated urban areas can be modelled. Two decomposition procedures are applied in this paper. The first one is to validate the effectiveness of this scattering model. We regard the HV component from urban areas as cross-scattering, which is an independent scattering component added to the Yamaguchi’s four-component decomposition. Another one is the urban area decomposition application using this scattering model. Decomposition is implemented for urban and natural areas, and the HV component from urban areas is regarded as their volume scattering. This procedure is similar to many other state-of-the-art methods for urban areas and needs to discriminate the urban and natural areas before decomposition. Spaceborne Radarsat-2 C-band, the airborne synthetic aperture radar (AIRSAR) L-band, and uninhabited aerial vehicle synthetic aperture radar (UAVSAR) L-band full polarimetric SAR data are used to validate the performance of this cross-scattering coherency matrix. The HV component of orientated buildings is generated, leading to a better decomposition result for urban areas.

Unsupervised polarimetric SAR urban area classification based on model-based decomposition with cross scattering

Since it has been validated that cross-polarized scattering (HV) is caused not only by vegetation but also by rotated dihedrals, in this study, we use rotated dihedral corner reflectors to form a cross scattering matrix and propose an extended four-component model-based decomposition method for PolSAR data over urban areas. Unlike other urban area decomposition techniques which need to discriminate the urban and natural areas before decomposition, this proposed method is applied on PolSAR image directly. The building orientation angle is considered in this scattering matrix, making it flexible and adaptive in the decomposition. Therefore, we can separate cross scattering of urban areas from the overall HV component. Further, the cross and helix scattering components are also compared. Then, using these decomposed scattering powers, the buildings and natural areas can be easily discriminated from each other using a simple unsupervised K-means classifier. Moreover, buildings aligned and not aligned along the radar flight direction can be also distinguished clearly. Spaceborne RADARSAT-2 and airborne AIRSAR full polarimetric SAR data are used to validate the performance of our proposed method. The cross scattering power of oriented buildings is generated, leading to a better decomposition result for urban areas with respect to other state-of-the-art urban decomposition techniques. The decomposed scattering powers significantly improve the classification accuracy for urban areas.

Model-Based Decomposition With Cross Scattering for Polarimetric SAR Urban Areas

Cross-polarized scattering (HV) is not only caused by vegetation but also by rotated dihedrals. In this letter, we use rotated dihedral corner reflectors to form a cross scattering matrix and propose an extended model-based decomposition method for polarimetric synthetic aperture radar (PolSAR) data over urban areas. Unlike other urban decomposition techniques which need to discriminate between urban and natural areas before decomposition, this proposed method is applied directly on the PolSAR image. The building orientation angle is considered in this scattering matrix, making it flexible and adaptive in the decomposition process. This enables the separation of the cross scattering of urban areas from the overall HV component. The cross and helix scattering components are also compared in this study. RADARSAT-2 quad-pol C band and AIRSAR L band data are used to validate the performance of the proposed method. The cross scattering power of oriented buildings is generated, leading to a better decomposition result for urban areas with respect to other urban decomposition techniques.

A Comprehensive Evaluation of Drain-side Layout Topologies on the Power nLDMOS ESD/LU Reliabilities

The non-uniform turned-on and low holding-Voltage (V h) issues are seriously impacted the reliability abilities of an n-channel lateral-diffused power MOSFET (nLDMOS). Therefore, basing on the drain Field-Oxide Device (FOD) structure of an nLDMOS and changing the thin-Oxide Definition (OD) topology for contacts located in the middle region of drain-side will be investigated in this study. The OD structure will renew as some dotted-OD manners. Experimental results show that the dotted-OD layout has a higher Electrostatic Discharge (ESD) capability than that of the FOD structure and the layout type of dotted-OD will affect the ESD capability of an HV component. A uniformly distributed type of dotted-OD will have a highest I t2 value, the I t2 value is increased about 12% as compared with the Ref. traditional nLDMOS. And, the V h value will increase with the contacts number increasing within the dotted-OD, which is increased about 28.2% of a dotOD46 device as compared with the traditional nLDMOS. Furthermore, as adding an FODs structure combined with a uniform dotted-OD structure in the drain side will be haven a high ESD capability (about 5.9% increasing) and high LU immunity (25.8% increasing) compared with the traditional nLDMOS DUT. Therefore, it is good both for ESD and Latch-Up (LU) reliability considerations.

Thermogravimetric analysis of poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)

AbstractThe thermal degradation of poly(3‐hydroxybutyrate) (PHB) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) [P(HB‐HV)] was studied using thermogravimetry (TG). In the thermal degradation of PHB, the temperature at the onset of weight loss (To) was derived by To = 0.97B + 259, where B represents the heating rate (°C/min). The temperature at which the weight loss rate was maximum (Tp) was Tp = 1.07B + 273, and the final temperature (Tf) at which degradation was completed was Tf = 1.10B + 280. The percentage of the weight loss at temperature Tp (Cp) was 69 ± 1% whereas the percentage of the weight loss at temperature Tf (Cf) was 96 ± 1%. In the thermal degradation of P(HB‐HV) (7:3), To = 0.98B + 262, Tp = 1.00B + 278, and Tf = 1.12B + 285. The values of Cp and Cf were 62 ± 7 and 93 ± 1%, respectively. The derivative thermogravimetric (DTG) curves of PHB confirmed only one weight loss step change because the polymer mainly consisted of the HB monomer only. The DTG curves of P(HB‐HV), however, suggested multiple weight loss step changes; this was probably due to the different evaporation rates of the two monomers. The incorporation of 10 and 30 mol % of the HV component into the polyester increased the various thermal temperatures (To, Tp, andTf) by 7–12°C (measured at B = 20°C/min). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2237–2244, 2001

Aminolysis of poly (.BETA.-hydroxybutyrate) and its copolymer.

Poly (β-hydroxybutyrate) and its copolymer poly (β-hydroxybutyrate-co-β-hydroxyvalerate) P (HB-co-HV) were treated with methyl- and ethylamines. Melting peak temperatures, number-average molecular weights (Mn) and long spacings (L) of treated samples decreased as the concentration of amines or the treating time increased. However, Mn and L almost levelled off at the optimum conditions, where amorphous regions at the surfaces of crystal lamellae were removed to isolate the core parts of single crystals. The level-off Mn values corresponding to the real thickness of the crystal core were estimated. The equilibrium melting point of PHB was ca. 200°C which was estimated from the plot of melting point Tm against L-1. The content of HV component in the crystalline region of P (HB-co-20mol% HV) evaluated by 1H-NMR was 18mol%, which was slightly smaller than the initial composition (20mol%). This implies that a small number of HV units was excluded from the HB crystals due to the bulky side group of the HV unit.

Analysis of the composition of poly(.BETA.-hydroxybutyrate-.BETA.-hydroxyvalerate) by NMR.

Composition and comonomer sequence distribution of poly (β-hydroxybutyrate-β-hydroxy-valerate), P (HB-HV) copolyesters were estimated by 1H-and 13C-NMR. The composition of HV component estimated from 1H-NMR was considerably different from the quoted values (rough estimates announced by ICI). From the 13C-NMR study, it was estimated that P (HB-HV) copoly-esters are almost statistically random copolymers. The melting point vs. the composition curve was replotted using HV content thus estimated from the NMR study. Heat of fusion of P (HB-HV) derived from Flory plot was 6650 J mol-1 Crystallinity and end surface free energy estimated using this value decreased linearly as HV content increased.

Crystallization and Morphology of Poly(β-hydroxybutyrate) and Its Copolymer

The morphology and structure of the bacterial plastics of poly(β-hydroxy-butyrate-β-hydroxyvalerate) P(HB-HV) were studied as well as the reference homopolymer, poly(β-hydroxybutyrate) (PHB). Because of bacterial origins they are exceptionally pure. Crystallization behavior of them is expected to be almost ideal, so that we can easily infer how the minor component (HV) acts within the major component (HB). The solution-grown single crystals of PHB and P(HB-HV) showed linear increase in melting points and hyperbolic increase in long spacings as the crystallization temperature increased. The HV component in the polymer chain was inclined to be excluded outwards as much as possible from the crystal of HB component during the crystallization. A small part of the HV component included in the HB component crystal acts as a defect, by which small expansion of the a-parameter of the unit cell is mainly caused with increasing HV content. The severe effect of the HV component was observed on crystallization characteristics and morphological changes.

Study of the soot nucleation zone of rich methane-oxygen flames

Some aspects of the soot nucleation processes which take place in the reaction zone of an atmospheric pressure premixed flat methane/oxygen flame have been studied using a laser light scattering method and a gas chromatographic technique. A range of CH 4 /O 2 ratios of 0.9 to 1.27 was covered and the temperatures of the flames were varied by altering the inlet flow rate; in some experiments small amounts of ethylene or acetylene were added to the feeding mixtures. The maximum concentration of C 2 H 2 , C 4 H 2 and C 4 H 4 is increased when a higher R =CH 4 /O 2 ratio is used and, for the same R ratio, when the flame has a higher combustion temperature. The addition of C 2 H 2 and C 2 H 4 to the feeding mixtures increases the concentrations of all the unsaturated hydrocarbons. The angular patterns of the vertically and horizontally polarized components of the scattered light at λ 0 =514.5 nm were determined at different heights in the flame. It was found that in the reaction zone the vertical Q ˙ VV polarized components were due both to Rayleigh scattering by gas phase combustion products and to a contribution due to higher molecular weight substances. Higher combustion temperatures decrease the contribution of soot particles to the measured Q ˙ VV intensity, which is higher for richer mixtures. The depolarized Q ˙ HV component was much higher in the reaction zone than that predicted by the depolarization of the gas phase compounds. The Q ˙ VV / Q ˙ HV ratios pass through a maximum which is more pronounced and displaced toward the burner for higher CH 4 /O 2 mixtures. The extinction coefficients at λ 0 =514.5 nm in the reaction zone have also been measured and compared with the scatter results. The analysis of the experimental results shows that the formation and evolution of C 2 , C 3 and C 4 unsaturated hydrocarbons does not appear to be a process which takes place before soot nucleation. A part of the scattered signals in the first reaction zone is due to highly depolarized “anelastic” effects, whereas the depolarization in the burned gas region is due mainly to the anistropy of the soot particles. The minimum particle size observed, determined by the scatter/extinction method, is around 20 and the initial soot number concentration has a maximum of 10 13 cm −3 for the richest flame studied.