Large Area DPB Free (111) β-SiC Thick Layer Grown on (0001) α-SiC Nominal Surfaces by the CF-PVT Method

2005 ◽  
Vol 483-485 ◽  
pp. 225-228 ◽  
Author(s):  
Didier Chaussende ◽  
Laurence Latu-Romain ◽  
Laurent Auvray ◽  
M. Ucar ◽  
Michel Pons ◽  
...  
Keyword(s):  
Growth Rate ◽  
Optical Microscopy ◽  
Cross Section ◽  
Thick Layer ◽  
Vapour Transport ◽  
Large Area ◽  
Continuous Feed ◽  
Heating Up ◽  
Cross Section Geometry ◽  
Selection Of

Thick (111) oriented β-SiC layers have been grown by hetero-epitaxy on a (0001) a-SiC substrate with the Continuous Feed-Physical Vapour Transport (CF-PVT) method. The growth rate was 68 µm/h at a pressure of 2 torr and a temperature of 1950°C. The nucleation step of the β-SiC layer during the heating up of the process was studied in order to manage first the a to b heteropolytypic transition and second the selection of the b-SiC orientation. With a adapted seeding stage, we grew a 0.4mm thick layer almost free of Double Positioning Boundaries on a 30mm diameter sample. First observations of the layer by cross-polarised optical Microscopy are presented both in planar view and in cross section geometry.

scholarly journals RELIEF DEVELOPMENT OF THE BABIA GÓRA MASSIF, WESTERN CARPATHIAN MOUNTAINS

2014 ◽  
Vol 33 (1) ◽  
pp. 89-106
Author(s):  
Adam Łajczak
Keyword(s):  
Cross Section ◽  
Thick Layer ◽  
Northern Slope ◽  
Large Area ◽  
Carpathian Mountains ◽  
Aerial Photos ◽  
Tectonic Faults ◽  
Geological Maps ◽  
Landform Development ◽  
Steep Slopes

Abstract The paper discusses structural considerations relating to landform development on Mt. Babia Góra (1,725 m a.s.l.), the highest massif in the flysch section of the Western Carpathian Mountains. The Babia Góra massif consists of folded Palaeogene-age sediments, including resistant Magura sandstone and less resistant sub-Magura layers, with numerous tectonic faults. The area has inverse-type geomorphology. The monoclinal ridge of the massif itself consists of the resistant Magura sandstone dipping southwards. Since the Miocene, the development of the massif’s relief has involved a number of processes, including: tectonic uplifting, removal of a thick layer of rocks, exposure of sub-Magura layers over a large area, the staged development of valleys dissecting the pediments surrounding the ever higher ridge, and slope retreat due to deep landsliding. Axes of linear terrain forms, escarpments of landslide scars and of headwater areas follow two main intersecting fracture lines present within the massif. Large quantities of colluvial material are transported away from the massif along these lines. The development of the land relief has led to the elongation of slopes as local elevation differences increased. Landsliding has developed in an uphill direction, which means that the youngest relief is observed on the highest sections of steep slopes. The development of the massif’s northern slope, which has formed a high and precipitous cuesta, began to accelerate only after a nearly complete exposure of the sub-Magura layers at its foot. Following this exposure the profile of the massif’s N-S cross-section has begun to become asymmetrical. With time, the degree of general remodelling of the massif has tended to decrease. As a result, the geomorphological contrast between the northern and southern sides of the massif has become well established. The description of the probable development of the Babia Góra relief is based on the author’s fieldwork, an analysis of geological maps and aerial photos, and on literature.

An evaluation of some criteria used in selecting large-yielding tea clones

1971 ◽  
Vol 76 (1) ◽  
pp. 143-156 ◽  
Author(s):  
M. J. Green
Keyword(s):  
Growth Rate ◽  
Cross Section ◽  
Vegetative Propagation ◽  
Selection Criterion ◽  
Calcium Oxalate Crystals ◽  
Rate Of Development ◽  
Phloem Parenchyma ◽  
Plant Grown ◽  
Rates Of Growth ◽  
Selection Of

SUMMARYSeveral criteria which have been used hitherto in the hope of selecting large-yielding clones of tea have been examined. The heights, girths, root weights and branching a gles of young seedlings in the nursery are correlated with the sizes and yields of the same plants when mature, but not with the rates of growth in the nursery, or the yields at maturity, of the plants derived from these seedlings by vegetative propagation. The pruning weight, size and yield of a mature plant grown from seed are not related to the rate of growth in the nursery or the yield at maturity of the clone derived from that plant. The proportion of cuttings which form roots and the growth rate of the cuttings of a clone are not related to the yield of the clone. It is concluded that these criteria are, at best, of limited value in the selection of large-yielding clones.Phloem Index, which is the number of calcium oxalate crystals counted in the phloem parenchyma in a cross-section of the petiole, varies with the age and rate of development of the shoot from which the petiole is taken and with the concentration of nutrients in the soil. It is therefore not useful as an alternative selection criterion under normal field conditions.

Automated 3D measurement of fiber cross section morphology in handsheets

2012 ◽  
Vol 27 (2) ◽  
pp. 264-269 ◽  
Author(s):  
Christian Lorbach ◽  
Ulrich Hirn ◽  
Johannes Kritzinger ◽  
Wolfgang Bauer
Keyword(s):  
Image Analysis ◽  
Cross Section ◽  
Cross Sections ◽  
Image Plane ◽  
3D Measurement ◽  
Cross Sectional ◽  
Fiber Cross Section ◽  
Fiber Wall ◽  
Sectional Shape ◽  
Cross Section Geometry

Abstract We present a method for 3D measurement of fiber cross sectional morphology from handsheets. An automated procedure is used to acquire 3D datasets of fiber cross sectional images using an automated microtome and light microscopy. The fiber cross section geometry is extracted using digital image analysis. Simple sample preparation and highly automated image acquisition and image analysis are providing an efficient tool to analyze large samples. It is demonstrated that if fibers are tilted towards the image plane the images of fiber cross sections are always larger than the true fiber cross section geometry. In our analysis the tilting angles of the fibers to the image plane are measured. The resulting fiber cross sectional images are distorted to compensate the error due to fiber tilt, restoring the true fiber cross sectional shape. We use an approximated correction, the paper provides error estimates of the approximation. Measurement results for fiber wall thickness, fiber coarseness and fiber collapse are presented for one hardwood and one softwood pulp.

Optimising the A/O cycle for phosphorus removal in a submerged biofilter under continuous feed

2000 ◽  
Vol 41 (4-5) ◽  
pp. 503-508 ◽  
Author(s):  
R.F. Gonçalves ◽  
F. Rogalla
Keyword(s):  
Phosphorus Removal ◽  
Organic Substrate ◽  
P Element ◽  
Enhanced Biological Phosphorus Removal ◽  
Biological Phosphorus Removal ◽  
P Release ◽  
Continuous Feed ◽  
Biological Phosphorus ◽  
Total P ◽  
Selection Of

This work describes laboratory scale research about Enhanced Biological Phosphorus Removal (EBPR) in a submerged biofilter under Anaerobic/Oxic (A/O) alternation and continuous feed. Its main purpose is to detail the behaviour of the reactor throughout the anaerobic and the aerobic phases of the A/O cycle, to study the importance of the anaerobic phase in the selection of the EBPR bacteria in the biofilm and to evaluate the consumption and the importance of the organic substrate during the anaerobic phase. The mass balance over the Phosphorus (P) element indicates that long anaerobic phases (6 h) are more efficient than short ones (3 h) as a selector of EBPR bacteria in biofilms. In both comparisons, thespecific mass of P released in a 6 h period represents almost 50% more than the amount of P release in the shorter period (3 h). However, the presence of rapidly biodegradable COD in the influent of the anaerobic phase is a more effective selector, more important than the duration of the anaerobic phase: by doubling the amount of acetic acid in the influent, a similar 50% increase of P-release can be achieved at short anaerobic periods of 3 h. The effect of the strategy adopted in this study, focusing on selecting EBPR bacteria in biofilm, is shown by the P levels of 4% (total P/SST) in the sludge removed from the BF by backwashing in all periods.

scholarly journals A possible radio signal of annihilating dark matter in the Abell 4038 cluster

2019 ◽  
Vol 495 (1) ◽  
pp. L124-L128 ◽  
Author(s):  
Man Ho Chan ◽  
Chak Man Lee
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Radio Signal ◽  
Dark Matter Particle ◽  
Cosmic Ray ◽  
Annihilation Cross Section ◽  
Radio Continuum ◽  
Test Statistic ◽  
Large Area ◽  
Dark Matter Annihilation

ABSTRACT In the past decade, some telescopes [e.g. Fermi-Large Area Telescope (LAT), Alpha Magnetic Spectrometer(AMS), and Dark Matter Particle Explorer(DAMPE)] were launched to detect the signals of annihilating dark matter in our Galaxy. Although some excess of gamma-rays, antiprotons, and electrons/positrons have been reported and claimed as dark matter signals, the uncertainties of Galactic pulsars’ contributions are still too large to confirm the claims. In this Letter, we report a possible radio signal of annihilating dark matter manifested in the archival radio continuum spectral data of the Abell 4038 cluster. By assuming the thermal annihilation cross-section and comparing the dark matter annihilation model with the null hypothesis (cosmic ray emission without dark matter annihilation), we get very large test statistic values >45 for four popular annihilation channels, which correspond to more than 6.5σ statistical preference. This provides a very strong evidence for the existence of annihilating dark matter. In particular, our results also support the recent claims of dark matter mass m ≈ 30–50 GeV annihilating via the bb̄ quark channel with the thermal annihilation cross-section.

scholarly journals In-situ SEM and optical microscopy testing for investigation of fatigue crack growth mechanism under overload

2018 ◽  
Vol 165 ◽  
pp. 13013
Author(s):  
Wei Zhang ◽  
Liang Cai
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Optical Microscopy ◽  
Crack Growth ◽  
Load Condition ◽  
Crack Tip ◽  
Initial Crack ◽  
Crack Growth Behavior ◽  
Single Overload

In this paper, the in-situ scanning electron microscope (SEM) and optical microscopy experiments are performed to investigate the crack growth behavior under the single tensile overload. The objectives are to (i) examine the overload-induced crack growth micromechanisms, including the initial crack growth acceleration and the subsequent retardation period; (ii) investigate the effective region of single overload on crack growth rate. The specimen is a small thin Al2024-T3 plate with an edge-crack, which is loaded and observed in the SEM chamber. The very high resolution images of the crack tip are taken under the simple variable amplitude loading. Imaging analysis is performed to quantify the crack tip deformation at any time instant. Moreover, an identical specimen subjected to the same load condition is observed under optical microscope. In this testing, fine speckling is performed to promote the accuracy of digital imaging correlation (DIC). The images around the crack tip are taken at the peak loads before, during and after the single overload. After that, the evolution of local strain distribution is obtained through DIC technique. The results show that the rapid connection between the main crack and microcracks accounts for the initial crack growth acceleration. The crack closure level can be responsible for the crack growth rate during the steady growth period. Besides that, the size of retardation area is larger than the classical solution.

Controlling the dynamic behavior of piezoceramic cylinders by cross-section geometry

2012 ◽  
Vol 223 (6) ◽  
pp. 1119-1136 ◽  
Author(s):  
Jan Awrejcewicz ◽  
Valeriy Storozhev ◽  
Vladimir Puzyrev
Keyword(s):  
Dynamic Behavior ◽  
Cross Section ◽  
Cross Section Geometry

Piezoelectric T-Beam Microactuators

2008 ◽  
Author(s):  
Hareesh K. R. Kommepalli ◽  
Andrew D. Hirsh ◽  
Christopher D. Rahn ◽  
Srinivas A. Tadigadapa
Keyword(s):  
Cross Section ◽  
Fabrication Process ◽  
Mems Fabrication ◽  
Out Of Plane ◽  
Cantilevered Beam ◽  
Piezoelectric Mems ◽  
The Cross ◽  
T Beam ◽  
Cross Section Geometry

This paper introduces a novel T-beam actuator fabricated by a piezoelectric MEMS fabrication process. ICP-RIE etching from the front and back of a bulk PZT chip is used to produce stair stepped structures through the thickness with complex inplane shapes. Masked electrode deposition creates active and passive regions in the PZT structure. With a T-shaped crosssection, and bottom and top flange and web electrodes, a cantilevered beam can bend in-plane and out-of-plane with bimorph actuation in both directions. One of these T-beam actuators is fabricated and experimentally tested. An experimentally validated model predicts that the cross-section geometry can be optimized to produce higher displacement and blocking force.

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