bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Analysis of the Surface Roughness Parameters due to the Machining Uniformity
Authors: Golabczak Andrzej , Konstantynowicz Andrzej , Golabczak Marcin
Published: June 2016

In the paper a new method has been proposed for the determining of the very fine machining uniformity over the elaborated surface and could be applied to different machined materials and machining procedures. The proposed methodology is relatively simple and is essentially formulated in the few subsequent steps: taking surface roughness 3D profile accordingly proposed scheme; estimation of the roughness statistical parameters: Rp, Rv, Rt, Ra, Rq, Rskew, Rkurt, and if need be – surface rugosity Ru; calculation of the centroid of the obtained data due to the measurement fields, calculation of the barycentre of the obtained data with the weighting variable chosen for the appropriate evaluation of the surface machining uniformity. As the main Cartesian coordinates of the centroid calculation we propose (Rskew, Rkurt), although other data organization schemes have also been provided as the example solutions. The final evaluation of the surface machining uniformity is based upon the Euclidean distance between the centroid and barycentre of the surface roughness data. The proposed method has been applied to experimental results obtained with the AFM technique used on samples of the polished AZ31 magnesium alloy. The surface machining procedure comprised of four stages performed with using different abrasive media, finally lead to the highest grade of the surface roughness.
Corrosion Monitoring of the Active/Passive/Transpassive State of a High-Alloy CrMnNi Steel by Means of Acoustic Emissions
Authors: Mandel Marcel , Kietov Wladimir , Krueger Lutz
Published: June 2016

The corrosion behaviour of a high-alloy CrMnNi steel was investigated electrochemically in a 0.5 M sulphuric acid solution. The characteristic regions of the active, passive and transpassive state for the material were monitored by means of acoustic emissions. To this end, the steel was potentiostatically polarised and the acoustic emission signal was recorded on the specimen’s surface at a distance of 5 cm from the location of corrosion. Analysis of the acoustic emission signals revealed an increase in signal intensity due to hydrogen bubble formation when the material was cathodically polarised. Furthermore, for anodic polarisation, a continuous decline in the signal-time correlation occurred when the material was polarised in the active/passive state, whereas a sharp point of inflexion and drastic reduction in intensity was recognised when the material was polarised in the passive state. Moreover, a further increase in signal intensity was observed when the transpassive state was reached. The increase at transpassivity was related to the onset of oxygen bubble formation at the electrode.
HF Transport Coefficients in Polymers Used for Microelectronic Applications
Authors: González-Aguirre P. , Fontaine Hervé , Beitia C. , Pastorello R. , Ohlsen J. , Lundgren J.
Published: June 2016

In order to better understand the sorption and outgassing mechanism of gases in relation to wafers containers (FOUP), we have measured HF gas transport coefficients for different FOUP polymers. Gas sorption is governed by surface adsorption, followed by diffusion and solubility. Cross contamination between FOUP and wafer occurs when polymers outgas contaminants into the surrounding environment. Diffusion is the key parameter to understanding cross contamination within the FOUP environment. In this work, we present the transport coefficients obtained for gaseous HF at cleanroom conditions (Patm, 21 ± 2°C & 40% RH) using the sorption kinetic method, based on Fick’s law, for thin films (<80μm) of polycarbonate (PC), polyetherimide (PEI) and a low absorbing polymer named Entegris Barrier Material (EBM) that constitute FOUPs. The resulting kinetic curves show Fick’s behavior, where obtained HF diffusion coefficients are between 3.7 X10-10 and 42 x10-12 cm2/s and are significantly lower than diffusion coefficients obtained for H2O using a gas permeation method. Nevertheless, the similar order of magnitude between the HF and the H2O permeability coefficients obtained by the two methods validates the sorption kinetic method. Finally, the obtained coefficients were used in numerical simulation in order to forecast polymer behavior.
The Effect of Differences in the Diffusion Coefficients of Components on the Onset of Convection in Isothermal Multicomponent Systems
Authors: Kossov Vladimir , Zhavrin Yuriy , Fedorenko Olga
Published: June 2016

Two series of experiments on the formation of convective flows in multicomponent liquid and gaseous mixtures are considered. In the first series, the convective structures arising during the diffusion of a binary aqueous solution of salt and sugar in an aqueous solution of pure salt were studied using the schlieren method. The observed behavior of convective cells corresponds to the instability similar to the "finger structures". In the second series, the experiments were conducted to determine the effective diffusion coefficients as a function of pressure in gas mixtures 0.5504 CH4 + 0.4496 Ar – N2 and 0.5994 H2 + 0.4006 Ar – N2. Our experiments have shown that the onset of convective flows both in liquid and gaseous multicomponent mixtures is due to the difference in the interdiffusion coefficients of the components. The experimental data for the ternary gas mixtures are described in the framework of the linear theory of stability.
The Use of a Power Law Function for Fatigue Life Estimation for Block Loads
Authors: Böhm Ewelina , Kurek Marta , Łagoda Tadeusz , Łagoda Karolina
Published: June 2016

A new damage accumulation model based on a power law for fatigue life estimation is presented. The model has been created on the basis of functions of memory taken from psychology. The model derivation is presented as well as its basic properties. It takes into account the loading sequence. The experimental verification of the model is performed for experimental results taken from the literature for four material groups tested with block loading programs. The obtained calculation results are compared with results obtained with the use of Palmgren-Miner model. The model can be used for the determination of fatigue life, especially for block load fatigue tests.
Strip Yield Model Applicability to Crack Growth Predictions for Various Types of Fatigue Loading
Authors: Machniewicz Tomasz , Skorupa Małgorzata , Korbel Adam
Published: June 2016

The capability of the strip yield (SY) model to predict crack growth in structural steel is investigated. To this end the SY model implementation developed by the present authors is applied to simulate crack growth observed in S355J2 steel specimens under constant amplitude and simple variable amplitude loading. A particular attention is given to the calibration of the model using the constraint factors and examining whether tuning the model, based on constant amplitude loading, allows the adequate predictions for variable amplitude loading.
Comparison of the Experimental Results of the Calculation for Various Models of the Energy Parameter
Authors: Marcisz Ewa , Rozumek Dariusz
Published: June 2016

The paper presents results of fatigue life tests conducted on transverse, circular and square cross-section specimens of C45 steel with controlled amplitude of energy parameter. The experimental results were compared with results obtained from computations on energy parameter models by R. Pawliczek, C. T. Lachowicz and on the linear-elastic model.
Simulation of Crack Growth in a Cell Containing an Inclusion Using Cohesive Elements
Authors: Galkiewicz Jarosław
Published: June 2016

In this study, two cases of crack growth initiation from a foreign particle in a representative elementary volume are analyzed. The task is completed with a cohesive model implemented in ABAQUS. The results are compared with those obtained for an inclusion-free cell.
Fatigue Cracking of AA2519-Ti6Al4V Laminate Bonded by Explosion Welding
Authors: Sniezek Lucjan , Szachogluchowicz Ireneusz , Torzewski Janusz , Grzelak Krzysztof
Published: June 2016

This paper presents test results of AA2519/TI6AL4V composite laminate structure and mechanical properties. The composite laminate was merged by explosive welding using a transition AA1050 alloy layer. The tested composite after formation was annealed, quenched in water and then aged to strengthen it. The heat treatment process was carried out in order to improve the physical and strength properties of the laminate. Weld endurance properties were determined through fatigue testing performed in constant total deformation amplitude (εac) conditions.The paper also describes the influence of test conditions on hysteresis loop shape, process of cyclic material strengthening and weakening, and fatigue life. Low cycle test results were approximated using a straight line with the following formula: σa = K'(εap)n which enables the K'fatigue strength coefficient, and the n' cyclic strengthening index to be determined. Test results also include fatigue fracture surface analysis. Distinctive fatigue fissure characteristics were investigated through studying fatigue fracture surface microstructure using a scanning electron microscope.
Tests of Fracture Toughness of Laser-Welded Joints Made of Duplex 2205 Steel
Authors: Soltysiak Robert
Published: June 2016

The process of welding introduces geometric notches to the area of joined material in the form of a face and root of a weld as well as structural heterogeneity in the form of changed properties (as compared with the parent material) in the heat affected zone and the weld zone. The parent material, as compared with the zones formed by welding, may differ in fracture toughness. In this paper the results of tests of fracture toughness of DUPLEX 2205 steel laser-welded joints are presented. Butt-welded joints were made by use of an Nd-YAG disc laser with no filler. The fatigue crack was initiated in the parent material and in the area including both the heat affected zone as well as the weld zone. The tests showed higher fracture toughness of the welded joint area as compared with the parent material.
Fracture Analysis of EN AW-6063 Aluminum Alloy Thin-Walled Welded Stairs
Authors: Gołoś Krzysztof , Jastrzebski Maciej
Published: June 2016

In the paper extended experimental study and numerical analysis of fatigue strength of aluminum alloy EN AW – 6063 welded thin-walled aluminum structural stair construction is presented. The FEM calculations were carried out. In analysis the concept of the weak link was applied. The critical thin-walled welded tread stairs node was selected and the concept was verified experimentally for two variants of cyclic loading. The effect of cyclic loading on crack initiation and propagation in the welds and on residual strength was examined. It was observed the reduction in residual strength, i.e. 1.61% for the construction of thin-walled welded connection after 30 000 cycles, and about 6.19% after 100 000 cycles.
Verification of Methods Used for Fatigue Testing of Small Steel Specimens Taken from Existing Structures
Authors: Tomaszewski Tomasz , Sempruch Janusz , Strzelecki Przemysław
Published: June 2016

This paper presents results of fatigue tests performed on standard specimens and minispecimens taken from two EN 1.4301 acid-resistant steel plates of different thickness. The tests were required for determination of the state of vibrating machines made from the same material. The results confirmed that the proposed testing method can be used for experimental tests.
Fatigue Testing of Titanium Alloy Ti6Al4V Used in Medical Devices
Authors: Wirwicki Mateusz , Pejkowski Lukasz , Topolinski Tomasz
Published: June 2016

Because titanium alloy Ti6Al4V features low density, good corrosion resistance and biocompatibility, it a metal of choice for medicine, used in orthopedics, accident surgery and dentistry. The insertion of elements such as nitrogen, carbon, hydrogen, iron or oxygen improve fatigue strength of this material. This paper presents certain basic fatigue and monotonic tests performed on the alloy. We have proposed a unique sample geometry and sample dimensions smaller than the reference ones. The dimensions of the working part of the sample correspond to the geometry of a dental implant connector. This part of the implant has to withstand stresses that are both intricate and variable in time. We performed monotonic tensile strength tests and uniaxial fatigue tests using the Instron 8874 machine. Then, we examined the samples under a stereoscopic microscope and measured the fracture development angle.
Analysis of the State of Stress at the V-Hole Ended Notch for Mode II
Authors: Gołoś Krzysztof , Niepokolczycki Michał
Published: June 2016

FEM linear numerical analysis of stress distribution demonstrated that the model Zappalorto and Lazzarin for analysed V-hole ended notch, relatively correctly predicts the stress distribution at the tip of the notch, especially for small angles of opening. The maximum levels of hoop stress and a tangential for load Mode II strongly dependent on the radius of the notch. The stress reaches its maximum value at a certain distance from the tip of the notch, approximately equal to half of the hole circle radius. The most effective way to reduce the levels of maximum stress at the notch is to increase the radius. When changing radius of 0.5 mm to 2 mm can reduce the degree of stress concentration approx. 40%.
Investigations on Magnetoelectric Composites Based on Terfenol-D & PZT in an Alternating Magnetic Field Conditions
Authors: Kaleta Jerzy , Lewandowski Daniel , Mech Rafał , Wozniak Karolina
Published: June 2016

In this paper a study on the magnetostrictive-piezoelectric composite material with different configuration in a variety of external magnetic field changes was presented. An experimental setup for investigation of properties of magnetostrictive-piezoelectric materials was prepared. The hybrid structure was made of magnetostrictive composite (based on Terfenol-D) and piezoelectric materials. Experimental results shown the response of prepared hybrid material to the rate of magnetic field changes at the same direction of magnetic field vector. Based on the obtained results, it was found that the prepared composite material exhibits magneto-electric effect in the case of work in a variable magnetic field. This phenomenon could be used as a support for the tensiometers during measurements of deformation or cracks propagation of the samples during fatigue tests.
Analysis of Ceramic Elements with Ring-Crack Defects in Lubricated Rolling Contact
Authors: Karaszewski Waldemar
Published: June 2016

The properties of ceramics, specifically low density, high hardness, high temperature capability and low coefficient of thermal expansion are of most interest to rolling element manufacturers. Surface ring cracks on lubricating rolling contact fatigue failure has been studied using numerical fracture analysis. Such cracks are very often found on ceramic bearing balls and decrease fatigue life rapidly. The numerical calculations are based on a three-dimensional model of the ring crack. The stress intensity factors along crack front are analyzed using a finite element analysis. The numerical analysis is verified by experimental studies.
Mean Stress in Algorithms Estimating Fatigue Life of Selected Structural Materials
Authors: Kluger Krzysztof , Pawliczek Roland
Published: June 2016

The paper presents comparison of the mathematical models for fatigue life calculations including influence of the mean load value. Several model based on stress analysis on the critical plane and energy density parameter were investigated. In this paper three types of materials were tested and subjected to bending, torsion and combination of bending with torsion loading with the participation of mean value of the load. It was found, that the best fatigue life estimations obtained by models taking into account changes of the material behavior under fatigue loading related to the specified numbers of cycles of the load.
Equivalent Fatigue Zone in a Notched Elements Determined by Use of Non-Local Line Method with Weight Function
Authors: Krzyzak Daniel , Robak Grzegorz , Łagoda Tadeusz
Published: June 2016

The work presents non-local line method by which the equivalent fatigue zones were designated. These zones are one-dimensional efficient lengths in which operating stress variables cause initiation of fatigue cracks. The algorithm of the presented method considers the issues of multi-axial stress state, critical plane and weighting function. Calculations of stresses in the test element were performed by using the FEM assuming cyclic material properties, which are described with the model for multi-linear hardening. The empirical lifetime of elements with a notch was assumed to define length of the crack amounting to 0.1 mm. As the result of calculations, the dependence of effective length on nominal stress and radius of the notch was determined.
Validation of K46, a Pup1-linked marker, using a selection of Sri Lankan rice (Oryza sativa L.) germplasm for marker assisted selection towards phosphorous deficiency tolerance
Authors: Aluwihare Y. C. , Chamikara M. D. M. , Dissanayake D. R. R. P. , Karannagoda N. N. H. , Sirisena D. N. , Samarasinghe W.L.G. , Rajapakse S. , Sooriyapathirana S. D. S. S
Published: June 2016

Phosphorous deficiency (PD) tolerance is a pivotal trait that is advantageous if present in modern day high performing rice varieties. However most of the frequently grown mega rice varieties lack this trait leading to expensive application of artificial phosphate fertilizer results secondary consequences such as environmental pollution and higher cost of production. Marker assisted breeding (MAB) for PD tolerance in rice is often hailed as the pragmatic solution to tackle this problem. The genetic basis of PD tolerance in rice has been dissected using a wide cross made between PD tolerant rice landrace Kasalath and a sensitive landrace Nipponbare. A major QTL known as Pup1 has been identified, molecularly characterized and underlying polymorphisms were detected. A major INDEL region within Pup1 QTL within Kasalath background is conferred to control the PD tolerance which is genetically ‘null’ in Nipponbare background. The DNA marker K46 which is present within Pup1 has been developed to identify this INDEL region in Kasalath like genotypes. The PD tolerance in Sri Lankan rice germplasm has been recently studied using a core panel of rice genotypes that are important in rice breeding programs. It is important to figure out the genomic landscape of the INDEL region of Pup1 QTL in these Sri Lankan rice genotypes. Therefore the present study was conducted to characterize the K46 DNA marker locus of the previously characterized for PD tolerance rice cultivars in Sri Lanka. The K46 specific primer-pair was assayed across 30 selected Sri Lankan cultivars and the PCR products were sequenced. The resulted DNA sequences were aligned with the Kasalath reference sequence for K46 locus. Further cluster analysis of the identified SNPs resulted four distinct haplotypes in which nine cultivars were grouped with Kasalath like haplotype, two unique haplotypes and the null haplotype. However, there is no strong association between the haploype class and the PD tolerance score of the cultivars implying the potentially novel PD tolerance mechanisms that require further studies.
Phytotoxicity, cytotoxicity and antioxidant activity of the invasive shrub Austroeupatorium inulifolium (Kunth) R.M. King & H. Rob
Authors: Chandrasiri Indika , Diwakara Shashini , Bandara Chamara Janaka , Wijesundara Siril , Madawala Sumedha , Karunaratne Veranja
Published: June 2016

Methanol and dichloromethane extracts of root, stem, leaves and flowers of invasive plant Austroeupatorium inulifolium were tested for cytotoxic, phytotoxic, antioxidant and antifungal activities. Significantly higher phytotoxicity was detected in methanol extracts of leaves and dichloromethane extracts of roots. This effect was most pronounced against amaranth seeds where the seed germination was reduced to 3.74 % with the addition of methanol extracts of leaves at 3000 mg/L.  The dichloromethane extract of roots of A. inulifolium showed potent antifungal activity against Cladosporium cladosporioides.  Cytotoxic activity was found in dichloromethane extract of roots (LD50 = 27.91 ± 8.55 mg/L), methanol extract of flowers (LD50 = 15.22±7.89 mg/L) and leaves (LD50 = 22.92±11.76 mg/L) against Artemia salina (brine shrimp) larvae.  The results also revealed significant antioxidant activity in methanol extract of leaves (IC50 =33.66± 0.03 mg/L) against the reference α-tocopherol (IC50 =10.02 ± 0.01 mg/L).
Phenetic Diversity and Preliminary Phytochemical Screening of Tephrosia Pers. Spp. (Family Fabaceae) in Sri Lanka
Authors: Priyadarshan A. I. S. , Senanayake S. P. , Jayatilleke M. P. , Rajapakse S.
Published: June 2016

Tephrosia is a genus of medicinally important perennial shrubs or herbs distributed in warm temperate and tropical regions, and belongs to Family Fabaceae. The genus is represented in Sri Lanka with 10 species. The objective of the present study was to interpret interspecific relationships of Tephrosia species in Sri Lanka using phenetic and phytochemical variations. Specimens of six different Tephrosia species including T. purpurea, T. villosa, T. noctiflora, T. tinctoria, T. maxima and T. pumila were collected from their natural habitats in different climatic zones in Sri Lanka.  Sixteen floral and vegetative characters of Tephrosia spp. were observed and cluster analysis was performed to interpret phenetic relationships. Herbarium specimens were prepared and voucher specimens were submitted to the National Herbarium, Peradeniya.  Phenogram indicated the presence of interspecific relationship with respect to the morphological characters. Air dried leaves were subjected to sequential solvent extractions using solvents with different polarities such as hexane, chloroform and methanol. These extracts were subjected to preliminary phytochemical screening tests to detect the occurrence of carbohydrates, protein and amino acids, glycosides, alkaloids, saponins, flavonoids, tannins, phenolics, and phytosteroids. Phytochemical screening of the different Tephrosia spp. indicated a close relationship among the species and further isolations and purifications are needed to elucidate the chemical constituents to assess the efficacy.
What Happens in the Thymus Does Not Stay in the Thymus: How T Cells Recycle the CD4+–CD8+ Lineage Commitment Transcriptional Circuitry To Control Their Function
Authors: Vacchio Melanie S. , Bosselut Rémy
Published: June 2016

MHC-restricted CD4+ and CD8+ T cells are at the core of most adaptive immune responses. Although these cells carry distinct functions, they arise from a common precursor during thymic differentiation, in a developmental sequence that matches CD4 and CD8 expression and functional potential with MHC restriction. Although the transcriptional control of CD4+–CD8+ lineage choice in the thymus is now better understood, less was known about what maintains the CD4+ and CD8+ lineage integrity of mature T cells. In this review, we discuss the mechanisms that establish in the thymus, and maintain in postthymic cells, the separation of these lineages. We focus on recent studies that address the mechanisms of epigenetic control of Cd4 expression and emphasize how maintaining a transcriptional circuitry nucleated around Thpok and Runx proteins, the key architects of CD4+–CD8+ lineage commitment in the thymus, is critical for CD4+ T cell helper functions.
A sharp quantitative estimate for the surface areas of convex sets in $\mathbb R^3$
Authors: Carozza Menita , Giannetti Flavia , Leonetti Francesco , Passarelli di Napoli Antonia
Published: June 2016

Let

E \subset B \subset \mathbb R^3

be closed, bounded, convex sets. It is known that the monotonicity of the surface areas holds, i.e.

\mathcal{H}^{2}(\partial E) \leqslant \mathcal{H}^{2}(\partial B)

. Here we give a quantitative estimate of the difference of the surface areas from below depending on the Hausdorff distance between

E

and

B

. Moreover, we construct an example which shows the sharpness of our result.
Hölder continuity up to the boundary for a class of fractional obstacle problems
Authors: Korvenpää Janne , Kuusi Tuomo , Palatucci Giampiero
Published: June 2016

We deal with the obstacle problem for a class of nonlinear integro-differential operators, whose model is the fractional

p

-Laplacian with measurable coeffcients. In accordance with well-known results for the analog for the pure fractional Laplacian operator, the corresponding solutions inherit regularity properties from the obstacle, both in the case of boundedness, continuity, and Hölder continuity, up to the boundary.
Impact of Siberian forest fires on the atmosphere over the Korean Peninsula during summer 2014
Authors: Jung Jinsang , Lyu Youngsook , Lee Minhee , Hwang Taekyung , Lee Sangil , Oh Sanghyub
Published: June 2016

Abstract. Extensive forest fires occurred during late July 2014 across the forested region of Siberia, Russia. Smoke plumes emitted from Siberian forest fires underwent long-range transport over Mongolia and northeast China to the Korean Peninsula, which is located  ∼  3000 km south of the Siberian forest. A notably high aerosol optical depth of  ∼  4 was observed at a wavelength of 500 nm near the source of the Siberian forest fires. Smoke plumes reached 3–5 km in height near the source and fell below 2 km over the Korean Peninsula. Elevated concentrations of levoglucosan were observed (119.7 ± 6.0 ng m−3), which were  ∼  4.5 times higher than those observed during non-event periods in July 2014. During the middle of July 2014, a haze episode occurred that was primarily caused by the long-range transport of emission plumes originating from urban and industrial complexes in East China. Sharp increases in SO42− concentrations (23.1 ± 2.1 µg m−3) were observed during this episode. The haze caused by the long-range transport of Siberian forest fire emissions was clearly identified by relatively high organic carbon (OC) ∕ elemental carbon (EC) ratios (7.18 ± 0.2) and OC ∕ SO42− ratios (1.31 ± 0.07) compared with those of the Chinese haze episode (OC ∕ EC ratio: 2.4 ± 0.4; OC ∕ SO42− ratio: 0.21 ± 0.05). Remote measurement techniques and chemical analyses of the haze plumes clearly show that the haze episode that occurred during late July 2014 was caused mainly by the long-range transport of smoke plumes emitted from Siberian forest fires.
A model inter-comparison study to examine limiting factors in modelling Australian tropical savannas
Authors: Whitley Rhys , Beringer Jason , Hutley Lindsay B. , Abramowitz Gab , De Kauwe Martin G. , Duursma Remko , Evans Bradley , Haverd Vanessa , Li Longhui , Ryu Youngryel , Smith Benjamin , Wang Ying-Ping , Williams Mathew , Yu Qiang
Published: June 2016

Abstract. The savanna ecosystem is one of the most dominant and complex terrestrial biomes, deriving from a distinct vegetative surface comprised of co-dominant tree and grass populations. While these two vegetation types co-exist functionally, demographically they are not static but are dynamically changing in response to environmental forces such as annual fire events and rainfall variability. Modelling savanna environments with the current generation of terrestrial biosphere models (TBMs) has presented many problems, particularly describing fire frequency and intensity, phenology, leaf biochemistry of C3 and C4 photosynthesis vegetation, and root-water uptake. In order to better understand why TBMs perform so poorly in savannas, we conducted a model inter-comparison of six TBMs and assessed their performance at simulating latent energy (LE) and gross primary productivity (GPP) for five savanna sites along a rainfall gradient in northern Australia. Performance in predicting LE and GPP was measured using an empirical benchmarking system, which ranks models by their ability to utilise meteorological driving information to predict the fluxes. On average, the TBMs performed as well as a multi-linear regression of the fluxes against solar radiation, temperature and vapour pressure deficit but were outperformed by a more complicated nonlinear response model that also included the leaf area index (LAI). This identified that the TBMs are not fully utilising their input information effectively in determining savanna LE and GPP and highlights that savanna dynamics cannot be calibrated into models and that there are problems in underlying model processes. We identified key weaknesses in a model's ability to simulate savanna fluxes and their seasonal variation, related to the representation of vegetation by the models and root-water uptake. We underline these weaknesses in terms of three critical areas for development. First, prescribed tree-rooting depths must be deep enough, enabling the extraction of deep soil-water stores to maintain photosynthesis and transpiration during the dry season. Second, models must treat grasses as a co-dominant interface for water and carbon exchange rather than a secondary one to trees. Third, models need a dynamic representation of LAI that encompasses the dynamic phenology of savanna vegetation and its response to rainfall interannual variability. We believe that this study is the first to assess how well TBMs simulate savanna ecosystems and that these results will be used to improve the representation of savannas ecosystems in future global climate model studies.
Sediment trap efficiency of paddy fields at the watershed scale in a mountainous catchment in northwest Vietnam
Authors: Slaets Johanna I. F. , Schmitter Petra , Hilger Thomas , Vien Tran Duc , Cadisch Georg
Published: June 2016

Abstract. Composite agricultural systems with permanent maize cultivation in the uplands and irrigated rice in the valleys are very common in mountainous southeast Asia. The soil loss and fertility decline of the upland fields is well documented, but little is known about reallocation of these sediments within the landscape. In this study, a turbidity-based linear mixed model was used to quantify sediment inputs, from surface reservoir irrigation water and from direct overland flow, into a paddy area of 13 ha. Simultaneously, the sediment load exported from the rice fields was determined. Mid-infrared spectroscopy was applied to analyze sediment particle size. Our results showed that per year, 64 Mg ha−1 of sediments were imported into paddy fields, of which around 75 % were delivered by irrigation water and the remainder by direct overland flow during rainfall events. Overland flow contributed one-third of the received sandy fraction, while irrigated sediments were predominantly silty. Overall, rice fields were a net sink for sediments, trapping 28 Mg ha−1 a−1 or almost half of total sediment inputs. As paddy outflow consisted almost exclusively of silt- and clay-sized material, 24 Mg ha−1 a−1 of the trapped amount of sediment was estimated to be sandy. Under continued intensive upland maize cultivation, such a sustained input of coarse material could jeopardize paddy soil fertility, puddling capacity and ultimately food security of the inhabitants of these mountainous areas. Preventing direct overland flow from entering the paddy fields, however, could reduce sand inputs by up to 34 %.
Manganese and iron reduction dominate organic carbon oxidation in deep continental margin sediments of the Ulleung Basin, East Sea
Authors: Hyun Jung-Ho , Kim Sung-Han , Mok Jin-Sook , Cho Hyeyoun , Lee Tongsup , Vandieken Verona , Thamdrup Bo
Published: June 2016

Abstract. Rates and pathways of benthic organic carbon (Corg) oxidation were investigated in surface sediments of the Ulleung Basin (UB) characterized by high organic carbon contents (> 2.5 %, dry wt.) and very high concentrations of Mn oxides (> 200 μmol cm−3) and Fe oxides (up to 100 μmol cm−3). The combination of geochemical analyses and independently executed metabolic rate measurements revealed that Mn and Fe reduction were the dominant Corg oxidation pathways in the center of the UB, comprising 45 % and 20 % of total Corg oxidation, respectively. By contrast, sulfate reduction was the dominant Corg oxidation pathway accounting for 50 % of total Corg mineralization in the continental slope. The relative significance of each Corg oxidation pathway matched the depth distribution of the respective electron acceptors. The relative importance of Mn reduction for Corg oxidation displays saturation kinetics with respect to Mn oxide content with a low half-saturation value of 8.6 µmol cm−3, which further implies that Mn reduction can be a dominant Corg oxidation process even in sediments with lower MnO2 content as known from several other locations. This is the first report of a high contribution of manganese reduction to Corg oxidation in offshore sediments on the Asian margin. The high manganese oxide content in the surface sediment in the central UB was maintained by an extreme degree of recycling, with each Mn atom on average being reoxidized ~ 3800 times before permanent burial. This is the highest degree of recycling so far reported for Mn-rich sediments, and it appears linked to the high benthic mineralization rates resulting from the high organic carbon content that indicate the UB as a biogoechemical hotspot for turnover of organic matter and nutrient regeneration. Thus, it is important to monitor any changes in the rates and partitioning of Corg oxidation to better understand the biogeochemical cycling of carbon, nutrients and metals associated with long-term climatic changes in the UB, where the fastest increase in sea water temperature has been reported for the past two decades.
1200 years of warm-season temperature variability in central Scandinavia inferred from tree-ring density
Authors: Zhang Peng , Linderholm Hans W. , Gunnarson Björn E. , Björklund Jesper , Chen Deliang
Published: June 2016

Abstract. Despite the emergence of new high-resolution temperature reconstructions around the world, only a few cover the Medieval Climate Anomaly (MCA). Here we present C-Scan, a new Scots pine tree-ring density-based reconstruction of warm-season (April–September) temperatures for central Scandinavia back to 850 CE, extending the previous reconstruction by 250 years. C-Scan is based on samples collected in a confined mountain region, adjusted for their differences in altitude and local environment, and standardised using the new RSFi algorithm to preserve low-frequency signals. In C-Scan, the warm peak of MCA occurs ca. 1000–1100 CE, and the Little Ice Age (LIA) between 1550 and 1900 CE. Moreover, during the last millennium the coldest decades are found around 1600 CE, and the warmest 10 and 30 years occur in the most recent century. By comparing C-Scan with other millennium-long temperature reconstructions from Fennoscandia, regional differences in multi-decadal temperature variability, especially during the warm period of the last millennium are revealed. Although these differences could be due to methodological reasons, they may indicate asynchronous warming patterns across Fennoscandia. Further investigation of these regional differences and the reasons and mechanisms behind them are needed.
REVISITING INTRINSIC CURVES FOR EFFICIENT DENSE STEREO MATCHING
Authors: Shahbazi M. , Sohn G. , Théau J. , Ménard P.
Published: June 2016

Abstract. Dense stereo matching is one of the fundamental and active areas of photogrammetry. The increasing image resolution of digital cameras as well as the growing interest in unconventional imaging, e.g. unmanned aerial imagery, has exposed stereo image pairs to serious occlusion, noise and matching ambiguity. This has also resulted in an increase in the range of disparity values that should be considered for matching. Therefore, conventional methods of dense matching need to be revised to achieve higher levels of efficiency and accuracy. In this paper, we present an algorithm that uses the concepts of intrinsic curves to propose sparse disparity hypotheses for each pixel. Then, the hypotheses are propagated to adjoining pixels by label-set enlargement based on the proximity in the space of intrinsic curves. The same concepts are applied to model occlusions explicitly via a regularization term in the energy function. Finally, a global optimization stage is performed using belief-propagation to assign one of the disparity hypotheses to each pixel. By searching only through a small fraction of the whole disparity search space and handling occlusions and ambiguities, the proposed framework could achieve high levels of accuracy and efficiency.
CLASSIFICATION OF AIRBORNE LASER SCANNING DATA USING GEOMETRIC MULTI-SCALE FEATURES AND DIFFERENT NEIGHBOURHOOD TYPES
Authors: Blomley R. , Jutzi B. , Weinmann M.
Published: June 2016

Abstract. In this paper, we address the classification of airborne laser scanning data. We present a novel methodology relying on the use of complementary types of geometric features extracted from multiple local neighbourhoods of different scale and type. To demonstrate the performance of our methodology, we present results of a detailed evaluation on a standard benchmark dataset and we show that the consideration of multi-scale, multi-type neighbourhoods as the basis for feature extraction leads to improved classification results in comparison to single-scale neighbourhoods as well as in comparison to multi-scale neighbourhoods of the same type.
FAST SEMANTIC SEGMENTATION OF 3D POINT CLOUDS WITH STRONGLY VARYING DENSITY
Authors: Hackel Timo , Wegner Jan D. , Schindler Konrad
Published: June 2016

Abstract. We describe an effective and efficient method for point-wise semantic classification of 3D point clouds. The method can handle unstructured and inhomogeneous point clouds such as those derived from static terrestrial LiDAR or photogammetric reconstruction; and it is computationally efficient, making it possible to process point clouds with many millions of points in a matter of minutes. The key issue, both to cope with strong variations in point density and to bring down computation time, turns out to be careful handling of neighborhood relations. By choosing appropriate definitions of a point’s (multi-scale) neighborhood, we obtain a feature set that is both expressive and fast to compute. We evaluate our classification method both on benchmark data from a mobile mapping platform and on a variety of large, terrestrial laser scans with greatly varying point density. The proposed feature set outperforms the state of the art with respect to per-point classification accuracy, while at the same time being much faster to compute.
POLE-LIKE STREET FURNITURE DECOMPOSTION IN MOBILE LASER SCANNING DATA
Authors: Li F. , Oude Elberink S. , Vosselman G.
Published: June 2016

Abstract. Automatic semantic interpretation of street furniture has become a popular topic in recent years. Current studies detect street furniture as connected components of points above the street level. Street furniture classification based on properties of such components suffers from large intra class variability of shapes and cannot deal with mixed classes like traffic signs attached to light poles. In this paper, we focus on the decomposition of point clouds of pole-like street furniture. A novel street furniture decomposition method is proposed, which consists of three steps: (i) acquirement of prior-knowledge, (ii) pole extraction, (iii) components separation. For the pole extraction, a novel global pole extraction approach is proposed to handle 3 different cases of street furniture. In the evaluation of results, which involves the decomposition of 27 different instances of street furniture, we demonstrate that our method decomposes mixed classes street furniture into poles and different components with respect to different functionalities.
PAIRWISE LINKAGE FOR POINT CLOUD SEGMENTATION
Authors: Lu Xiaohu , Yao Jian , Tu Jinge , Li Kai , Li Li , Liu Yahui
Published: June 2016

Abstract. In this paper, we first present a novel hierarchical clustering algorithm named Pairwise Linkage (P-Linkage), which can be used for clustering any dimensional data, and then effectively apply it on 3D unstructured point cloud segmentation. The P-Linkage clustering algorithm first calculates a feature value for each data point, for example, the density for 2D data points and the flatness for 3D point clouds. Then for each data point a pairwise linkage is created between itself and its closest neighboring point with a greater feature value than its own. The initial clusters can further be discovered by searching along the linkages in a simple way. After that, a cluster merging procedure is applied to obtain the finally refined clustering result, which can be designed for specialized applications. Based on the P-Linkage clustering, we develop an efficient segmentation algorithm for 3D unstructured point clouds, in which the flatness of the estimated surface of a 3D point is used as its feature value. For each initial cluster a slice is created, then a novel and robust slicemerging method is proposed to get the final segmentation result. The proposed P-Linkage clustering and 3D point cloud segmentation algorithms require only one input parameter in advance. Experimental results on different dimensional synthetic data from 2D to 4D sufficiently demonstrate the efficiency and robustness of the proposed P-Linkage clustering algorithm and a large amount of experimental results on the Vehicle-Mounted, Aerial and Stationary Laser Scanner point clouds illustrate the robustness and efficiency of our proposed 3D point cloud segmentation algorithm.
AIRBORNE MULTISPECTRAL LIDAR DATA FOR LAND-COVER CLASSIFICATION AND LAND/WATER MAPPING USING DIFFERENT SPECTRAL INDEXES
Authors: Morsy S. , Shaker A. , El-Rabbany A. , LaRocque P. E.
Published: June 2016

Abstract. Airborne Light Detection And Ranging (LiDAR) data is widely used in remote sensing applications, such as topographic and landwater mapping. Recently, airborne multispectral LiDAR sensors, which acquire data at different wavelengths, are available, thus allows recording a diversity of intensity values from different land features. In this study, three normalized difference feature indexes (NDFI), for vegetation, water, and built-up area mapping, were evaluated. The NDFIs namely, NDFIG-NIR, NDFIG-MIR, and NDFINIR-MIR were calculated using data collected at three wavelengths; green: 532 nm, near-infrared (NIR): 1064 nm, and mid-infrared (MIR): 1550 nm by the world’s first airborne multispectral LiDAR sensor “Optech Titan”. The Jenks natural breaks optimization method was used to determine the threshold values for each NDFI, in order to cluster the 3D point data into two classes (water and land or vegetation and built-up area). Two sites at Scarborough, Ontario, Canada were tested to evaluate the performance of the NDFIs for land-water, vegetation, and built-up area mapping. The use of the three NDFIs succeeded to discriminate vegetation from built-up areas with an overall accuracy of 92.51%. Based on the classification results, it is suggested to use NDFIG-MIR and NDFINIR-MIR for vegetation and built-up areas extraction, respectively. The clustering results show that the direct use of NDFIs for land-water mapping has low performance. Therefore, the clustered classes, based on the NDFIs, are constrained by the recorded number of returns from different wavelengths, thus the overall accuracy is improved to 96.98%.
OBJECT CLASSIFICATION VIA PLANAR ABSTRACTION
Authors: Oesau Sven , Lafarge Florent , Alliez Pierre
Published: June 2016

Abstract. We present a supervised machine learning approach for classification of objects from sampled point data. The main idea consists in first abstracting the input object into planar parts at several scales, then discriminate between the different classes of objects solely through features derived from these planar shapes. Abstracting into planar shapes provides a means to both reduce the computational complexity and improve robustness to defects inherent to the acquisition process. Measuring statistical properties and relationships between planar shapes offers invariance to scale and orientation. A random forest is then used for solving the multiclass classification problem. We demonstrate the potential of our approach on a set of indoor objects from the Princeton shape benchmark and on objects acquired from indoor scenes and compare the performance of our method with other point-based shape descriptors.
GPS-DENIED GEO-LOCALISATION USING VISUAL ODOMETRY
Authors: Gupta Ashish , Chang Huan , Yilmaz Alper
Published: June 2016

Abstract. The primary method for geo-localization is based on GPS which has issues of localization accuracy, power consumption, and unavailability. This paper proposes a novel approach to geo-localization in a GPS-denied environment for a mobile platform. Our approach has two principal components: public domain transport network data available in GIS databases or OpenStreetMap; and a trajectory of a mobile platform. This trajectory is estimated using visual odometry and 3D view geometry. The transport map information is abstracted as a graph data structure, where various types of roads are modelled as graph edges and typically intersections are modelled as graph nodes. A search for the trajectory in real time in the graph yields the geo-location of the mobile platform. Our approach uses a simple visual sensor and it has a low memory and computational footprint. In this paper, we demonstrate our method for trajectory estimation and provide examples of geolocalization using public-domain map data. With the rapid proliferation of visual sensors as part of automated driving technology and continuous growth in public domain map data, our approach has the potential to completely augment, or even supplant, GPS based navigation since it functions in all environments.
A GAUSSIAN PROCESS BASED MULTI-PERSON INTERACTION MODEL
Authors: Klinger T. , Rottensteiner F. , Heipke C.
Published: June 2016

Abstract. Online multi-person tracking in image sequences is commonly guided by recursive filters, whose predictive models define the expected positions of future states. When a predictive model deviates too much from the true motion of a pedestrian, which is often the case in crowded scenes due to unpredicted accelerations, the data association is prone to fail. In this paper we propose a novel predictive model on the basis of Gaussian Process Regression. The model takes into account the motion of every tracked pedestrian in the scene and the prediction is executed with respect to the velocities of all interrelated persons. As shown by the experiments, the model is capable of yielding more plausible predictions even in the presence of mutual occlusions or missing measurements. The approach is evaluated on a publicly available benchmark and outperforms other state-of-the-art trackers.
CHANGE DETECTION VIA MORPHOLOGICAL COMPARATIVE FILTERS
Authors: Vizilter Y. V. , Rubis A. Y. , Zheltov S. Y. , Vygolov O. V.
Published: June 2016

Abstract. In this paper we propose the new change detection technique based on morphological comparative filtering. This technique generalizes the morphological image analysis scheme proposed by Pytiev. A new class of comparative filters based on guided contrasting is developed. Comparative filtering based on diffusion morphology is implemented too. The change detection pipeline contains: comparative filtering on image pyramid, calculation of morphological difference map, binarization, extraction of change proposals and testing change proposals using local morphological correlation coefficient. Experimental results demonstrate the applicability of proposed approach.