bluuebunny/crossref_metadata_2025 huggingface dataset:
Failure on Bearing Cooler Coils Connector of Hydroelectric Power Plant
Authors: Nurbanasari Meilinda , Purwanto Tri Sigit , Kristyadi Tarsisius , Syamsurizal Deden
Published: June 2019

Bearing cooler coils connector of 175 MW hydropower plant experienced premature leaks after one year operation and caused an unscheduled shutdown. To avoid the same failure in the future, the leaking bearing cooler coils connector was investigated. Nondestructive tests, such as chemical composition analysis, hardness test, metallographic test, characterization of the filler brazing by scanning electron microscopy – energy dispersive X-ray spectroscopy were conducted. The results confirmed that the bearing cooler coils connector consisted of two types of material namely the flange material which was made of stainless steel 304 and the pipe material which was a Cu/Ni 90/10 and were joined together using brazing process. It was a clearly evidence that leaks occurred in the brazing area and the leakage was due to improper brazing process. It was shown by the excessive gap and a lot of porosity.
Effect of Latent Heat of Aluminum Alloys on Bonding between Strips in Clad Strip Cast by a Twin-Roll Caster
Authors: Haga Toshio
Published: June 2019

This study shows that the latent heat of the aluminum alloy in an overlay strip is the key factor affecting the bonding quality of clad strips fabricated by a vertical-type tandem twin-roll caster. Three-layer clad strips, for which the base strip was 3003 aluminum alloy and the overlay strip was Al-1%Si, Al-2%Si, Al-11%Si (4045), Al-2%Mg, and Al-4.5%Mg (5182), respectively, were cast. The 4045 overlay strip bonded to the base strip. However, overlay strips made of the other alloys did not bond to the base strip. The latent heat of Si is much higher than that of Al, which in turn is higher than that of Mg. Therefore, the latent heat of the 4045 alloy was higher than that of the other alloys. The high latent heat of the 4045 alloy allowed it to heat the base strip to a temperature at which bonding was possible.
Autophagy precedes apoptosis during degeneration of the Kölliker’s organ in the development of rat cochlea
Authors: Hou Shule , Chen Jiarui , Yang Jun
Published: June 2019

The Kölliker’s organ is a transient epithelial structure during cochlea development that gradually degenerates and disappears at postnatal 12-14 days (P12-14). While apoptosis has been shown to play an essential role in the degeneration of the Kölliker’s organ, the role of another programmed cell death, autophagy, remains unclear. In our study, autophagy markers including microtubule associated protein light chain 3-II (LC3-II), sequestosome 1 (SQSTM1/p62) and Beclin1 were detected in the supporting cells of the Kölliker’s organ through immunohistochemistry staining. In addition, Western blot and real-time PCR revealed a gradually decreased expression of LC3-II and an increased expression of p62 during early postnatal development. Compared to apoptosis markers that peaks between P7 and P10, autophagy flux peaked earlier at P1 and decreased from P1 to P14. By transmission electron microscopy, we observed representative autophagosome and autolysosome that packaged various organelles in the supporting cells of the Kölliker’s organ. During the degeneration, these organelles were digested via autophagy well ahead of the cellular apoptosis. These results suggest that autophagy plays an important role in transition and degeneration of the Kölliker’s organ prior to apoptosis during the early postnatal development.
Survey on visual acuity among intra-city commercial vehicle drivers in Ibadan, southwestern Nigeria
Authors: Dairo Magbagbeola David , Okechukwu-Nwankpa Ugochukwu Patricia , Nwankpa Romanus
Published: June 2019

Driving is recognized to be a visually intensive task and accordingly legal minimum standard of vision required for all motorists is stipulated. This study was carried out to find out how many commercial drivers in Ibadan North L.G.A met minimum legal requirement for driving in Nigeria. A cross sectional descriptive study was conducted among 340 commercial vehicle drivers selected by multistage sampling from eight transport stations (motor parks) in the city. Visual impairment was defined as vision acuity (VA) in both eyes which is below 3/18 but above 3/60 (VA <6/18≥3/60) and was assessed with the Snellen’s chart. All participants have valid driving licenses. One sixth [52, (15.3%)] have visual acuity below 6/9 and 18 (5.3%) have visual impairment (VA <6/18≥3/60). More of those drivers aged 40 years and more had visual impairment compared to the younger drivers (P<0.05). These findings suggest that regulatory standards for licensing drivers are being circumvented by some of the drivers. Mechanisms for ensuring compliance to the regulatory standards especially visual acuity is therefore recommended.
Method for measurement of snow depth using time-lapse photography
Authors: Fernandes R A , Bariciak T , Prévost C , Yao H , Field T , McConnell C , Luce J , Metcalfe R
Published: June 2019

Snow depth (SD) is an essential climate variable widely used for flood forecasting, water quantity assessments, road and building safety assessment, habitat assessment, and climate studies. Currently, SD is systematically monitored using manual ruler measurements
or dedicated instrumentation with a limited spatial footprint (~1m2). Here, an approach for automated SD estimation using images of narrow stakes remotely acquired by a 3Mpixel trail camera is described. The approach relies on the automated application of image processing and machine learning
algorithms packaged within a single freely available application deployed on a personal computer or cloud computing environment. The application requires minimal user input to define an initial template image and provides two independent estimates of SD at each stake that can be used to produce an
estimate of total uncertainty and sources of error. The system is compared to both manual ruler and ultrasonic instrument SD estimates at an open site and in a deciduous forest. Initial results over a melt period indicate the automated method agreed to within 1cm (RMSE) of manual ruler estimates and
to within 3.6cm of ultrasonic estimates; with the latter comparison including spatial variability between measurement locations. The automated system should be considered for further deployment and evaluation over a range of surface and climate conditions.
Where have all the ethics gone?
Authors: Eales C. J.
Published: June 2019

No abstract available
Supervision of qualified community rehabilitation workers
Authors: Petrick Monika , Sichangwa Kasenga , Collinson Mark , Pickford Katherine
Published: June 2019

Supervisors of Community Rehabilitation Workers (CRWs) have a critical role to play in supporting and developing the skills and effectiveness of CRWs. This paper reports on research conducted by the Wits/Tintswalo Community Rehabilitation, Research and Education (CORRE) Programme amongst past and present supervisors of qualified CRWs. The aim was to understand different approaches used in supervision, the problems encountered and possible solutions, and the perceived impact of CRWs within rehabilitation services.Thirteen supervisors of qualified CRWs completed a postal or hand delivered questionnaire, which contained a range of open-ended and semi-structured questions. The findings included the supervision activities, the problems around supervision and the benefit of a CRW service. The need for community based rehabilitation (CBR) practice protocols and standards was highlighted.These findings were one of a series of steps towards the development of a CBR management manual for the Northern Province.
Biomechanical changes of the oral and craniofacial regions as a result of altered breathing patterns
Authors: Jordaan R. , Papadopoulos M.
Published: June 2019

The purpose of this report is to discuss the biomechanical changes in the oral and craniofacial regions as a result of altered breathing patterns. The increase in air pollution and allergens, resulting in allergic reactions, is often the cause of chronic nasal obstruction. The biomechanics of the oral, cranial and facial areas are intimately linked, and will be adversely affected by any change in the breathing pattern. As a result of nasal obstruction, the biomechanics of respiration changes to facilitate mouth breathing, and the resting position of the tongue and mandible is disrupted. The lips are parted, the freeway space and craniocervical angulation increase. The muscle activity of the posterior cervical musculature, anterior temporalis and suprahyoid muscles will be increased. The equilibrium of forces in the oral and craniofacial region is disturbed, and these abnormal forces could lead to the development of “adenoid facies”, malocclusions and dysfunction over a period of time. It is important to diagnose chronic nasal obstruction and mouth breathing early and start treatment before the negative effects of the musculoskeletal system occur. A sound understanding of the biomechanical changes will enable the physiotherapist to carry out a skilful examination and plan a treatment program, based on informed decisions.
Characterisation of molten salts for their application to Molten Salt Reactors
Authors: Barnes Jake , Coutts Ryan , Horne Toby , Thai Jesse
Published: June 2019

Molten Salt Reactors (MSRs) are one of the six Gen (IV) reactor designs chosen by the Generation IV International Forum for further development. A key area of concern for MSRs is the selection of molten salt composition. Parameters such as heat capacity, thermal conductivity, and viscosity are essential to consider when selecting a salt mixture for use as a coolant in an MSR. In this meta-study, the thermodynamic properties of a range of halide, carbonate and nitrate salts are compared. Using this data, an estimate is made for the usable energy density of each salt. This value in combination with the raw data is used to assess the viability of each salt for use in an MSR. It was found that fluoride salts are the most suitable. They tend to have high heat capacities and large thermal conductivities in relation to the other salts in this study. The 50-50 concentration of LiF-BeF2 had by far the highest usable energy density at 2.21 J/cm3K, however its extremely high viscosity, of 22.2 mPa.s, makes it unsuitable for use as a circulating coolant. LiF-NaF-BeF2 had the next highest usable energy density at 1.82 Jcm-3K-1. Without considering factors beyond thermodynamic properties, it was concluded that LiF-NaF-BeF2, would be the most suitable of the studied salts for use as an MSR coolant. Much of the experimental data in this field was obtained over 40 years ago, it is often of poor quality, lacking standardisation and with large error margins. An attempt has been made in this paper to compile this data and to standardise it to such a degree that salts can be reasonable compared.

Keywords: Molten Salt Reactor; FLiBe; FLiNaK; Heat Capacity; Carnot Efficiency
A Meta-Analysis on the Advancement on the thermodynamic properties of clothing in extreme cold environments
Authors: Howie Nicholas , Rabey Samuel
Published: June 2019

When two systems with different energies are in contact, the heat from the higher energy system will move into the lower energy system and the two will reach equilibrium. Humans in extreme cold environments will perish if they do not keep appropriate heat contained within their system and thus it is the object of much historic research to maintain heat within a system for as long as possible. Research and development of cold weather clothing focuses on a range of methods regulating heat flow between clothing layers. Modern research focuses on air gaps between layers of clothing, development of new conventional insulating textiles and contemporary solutions such as the use of Phases Change [1]. The purpose of this paper is to conglomerate all of the current research into one meta-analysis highlighting the gaps in the research and potential areas in need of further study, and to propose a new article of cold weather apparel utilizing the most effective advancements from the papers collected in this study. It was found that each component of cold climate clothing affects an aspect of thermal resistivity. Thickness affects the windchill resistance, the specific heat increases thermal resistance of the fabric, while humidity increases thermal conductivity, air gaps reduce it and the rigidity affects all of these factors. Our findings suggest if the air gaps are above 8 mm, natural convection currents can occur which increase the thermal and moisture transfer between clothing layers. By analysing all of these factors, a new prototype garment was able to be proposed.

Keywords: Cold environment; clothing; thermoregulation.
Secondary organic aerosol enhanced by increasing atmospheric oxidizing capacity in Beijing–Tianjin–Hebei (BTH), China
Authors: Feng Tian , Zhao Shuyu , Bei Naifang , Wu Jiarui , Liu Suixin , Li Xia , Liu Lang , Qian Yang , Yang Qingchuan , Wang Yichen , Zhou Weijian , Cao Junji , Li Guohui
Published: June 2019

Abstract. The implementation of the Air Pollution Prevention and
Control Action Plan in China since 2013 has profoundly altered the ambient
pollutants in the Beijing–Tianjin–Hebei (BTH) region. Here we show
observations of substantially increased O3 concentrations (about
30 %) and a remarkable increase in the ratio of organic carbon (OC) to
elemental carbon (EC) in BTH during the autumn from 2013 to 2015, revealing
an enhancement in atmospheric oxidizing capacity (AOC) and secondary organic
aerosol (SOA) formation. To explore the impacts of increasing AOC on the SOA
formation, a severe air pollution episode from 3 to 8 October 2015 with high
O3 and PM2.5 concentrations is simulated using the WRF-Chem model.
The model performs reasonably well in simulating the spatial distributions
of PM2.5 and O3 concentrations over BTH and the temporal
variations in PM2.5, O3, NO2, OC, and EC concentrations in
Beijing compared to measurements. Sensitivity studies show that the change
in AOC substantially influences the SOA formation in BTH. A sensitivity case
characterized by a 31 % O3 decrease (or 36 % OH decrease) reduces
the SOA level by about 30 % and the SOA fraction in total organic aerosol
by 17 % (from 0.52 to 0.43, dimensionless). Spatially, the SOA decrease
caused by reduced AOC is ubiquitous in BTH, but the spatial relationship
between SOA concentrations and the AOC is dependent on the SOA precursor
distribution. Studies on SOA formation pathways further show that when the
AOC is reduced, the SOA from oxidation and partitioning of semivolatile primary organic aerosol
(POA)
and co-emitted intermediate volatile organic compounds (IVOCs) decreases
remarkably, followed by those from anthropogenic and biogenic volatile organic compounds (VOCs).
Meanwhile, the SOA decrease in the irreversible uptake of glyoxal and
methylglyoxal on the aerosol surfaces is negligible.
Supercooled liquid fogs over the central Greenland Ice Sheet
Authors: Cox Christopher J. , Noone David C. , Berkelhammer Max , Shupe Matthew D. , Neff William D. , Miller Nathaniel B. , Walden Von P. , Steffen Konrad
Published: June 2019

Abstract. Radiation fogs at Summit Station, Greenland (72.58∘ N,
38.48∘ W; 3210 m a.s.l.), are frequently reported by observers. The
fogs are often accompanied by fogbows, indicating the particles are composed
of liquid; and because of the low temperatures at Summit, this liquid is
supercooled. Here we analyze the formation of these fogs as well as their
physical and radiative properties. In situ observations of particle size and
droplet number concentration were made using scattering spectrometers near 2 and 10 m height from 2012 to 2014. These data are complemented by
colocated observations of meteorology, turbulent and radiative fluxes, and
remote sensing. We find that liquid fogs occur in all seasons with the
highest frequency in September and a minimum in April. Due to the
characteristics of the boundary-layer meteorology, the fogs are elevated,
forming between 2 and 10 m, and the particles then fall toward the surface.
The diameter of mature particles is typically 20–25 µm in summer.
Number concentrations are higher at warmer temperatures and, thus, higher in
summer compared to winter. The fogs form at temperatures as warm as −5 ∘C, while the coldest form at temperatures approaching −40 ∘C. Facilitated by the elevated condensation, in winter two-thirds of
fogs occurred within a relatively warm layer above the surface when the
near-surface air was below −40 ∘C, as cold as −57 ∘C,
which is too cold to support liquid water. This implies that fog particles
settling through this layer of cold air freeze in the air column before
contacting the surface, thereby accumulating at the surface as ice without
riming. Liquid fogs observed under otherwise clear skies annually imparted
1.5 W m−2 of cloud radiative forcing (CRF). While this is a small
contribution to the surface radiation climatology, individual events are
influential. The mean CRF during liquid fog events was 26 W m−2, and
was sometimes much higher. An extreme case study was observed to
radiatively force 5 ∘C of surface warming during the coldest part
of the day, effectively damping the diurnal cycle. At lower elevations of
the ice sheet where melting is more common, such damping could signal a role
for fogs in preconditioning the surface for melting later in the day.
Cloud responses to climate variability over the extratropical oceans as observed by MISR and MODIS
Authors: Geiss Andrew , Marchand Roger
Published: June 2019

Abstract. Linear temporal trends in cloud fraction over the extratropical oceans, observed by
NASA's Multi-angle Imaging SpectroRadiometer (MISR) during the period from
2000 to 2013, are examined in the context of coincident European Centre for
Medium-Range Weather Forecasts (ECMWF) reanalysis data using a maximum
covariance analysis. Changes in specific cloud types defined with respect to
cloud-top height and cloud optical depth are related to trends in reanalysis
variables. A pattern of reduced high-altitude optically thick cloud and
increased low-altitude cloud of moderate optical depth is found to be
associated with increased temperatures, geopotential heights, and
anti-cyclonic flow over the extratropical oceans. These and other trends in
cloud occurrence are shown to be correlated with changes in the El
Niño–Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO),
the North Pacific index (NPI), and the Southern Annular Mode (SAM).
Spatio Temporal Soil Moisture Dynamics and Runoff under Different Soil Cover Conditions in a Semiarid Representative Basin in Brazil
Authors: Montenegro Abelardo A. A. , Lopes Iug , de Carvalho Ailton A. , de Lima João L. M. P. , de Souza Thais E. M. S. , Araújo Helio L. , Lins Frederico A. C. , Almeida Thayná A. B. , Montenegro Hugo G. L. A.
Published: June 2019

Abstract. Hydrological studies in small basins are essential for
investigating the role of distinct processes on water resources conservation
and to assess the impact of the natural ecosystems on improving water
security especially in semiarid environments. In Brazil, the cooperative
hydrological Network REHISA (“REde de HIdrologia do SemiÁrido”)
comprises hydrologists from several universities of Brazil, focusing on
field measurements, monitoring and modeling activities in well instrumented
experimental rural catchments located at different regions and biomes in
Semiarid environment. Water scarcity is a common aspect among the
catchments, as well as risks of soil and water degradation. The objective of
this work is to present assessments of near surface soil moisture
spatial-temporal distribution, and to evaluate the impact of soil
conservation techniques in reducing runoff, using small-scale experimental
plots in a representative catchment of the Pernambuco State, Brazil. The
study catchment is located in Alto Ipanema River Basin (AIRB) (with an area
of 150 km2), which is located at the semiarid region of the São
Francisco River (area of 641 000 km2). Soil and water monitoring was
performed in experimental plots with different soil cover conditions (Bare
soil plots; Plots with natural cover – Caatinga Biome vegetation; Plots with
cactus Palma barriers; and Plots with mulch cover – Dry grass mulch at 4 t ha−1), where probes were installed for high resolution soil moisture
assessment. In addition, regular soil moisture monitoring campaigns were
conducted at 7 different locations, using a capacitance probe, with arboreal
and shrub Caatinga vegetation, pasture and bare soil, predominantly
Brachiaria decumbens. Mulch cover runs close to the Caatinga cover, but
still with higher runoff generation, and presenting lower soil moisture
temporal mean values. Caatinga was highly effective in terms of soil and
water conservation at the small basin scale for both the dry and the wet
season, resulting in a positive nexus between vegetation and water
availability at the region.
A new scenario applying traffic flow analogy to poleward expansion of auroras
Authors: Saka Osuke
Published: June 2019

Abstract. Transient westward electric fields from the magnetosphere generate
equatorward plasma drifts of the order of kilometers per second in the
auroral ionosphere. This flow channel extends in north–south directions and
is produced in the initial pulse of Pi2 pulsations associated with the field
line dipolarization. Drifts in the ionosphere of the order of kilometers per
second that accumulated plasmas at the low-latitude end of the flow channel
are of such large degree that possible vertical transport effects (including
precipitation) along the field lines may be ignored. In this condition, we
suggest that plasma compression in the ionosphere initiated the dynamic
ionosphere. The dynamic ionosphere includes a nonlinear evolution of the
compressed ionospheric plasmas, generation of field-aligned currents to
satisfy the quasi-neutrality of the ionosphere, and parallel potentials
associated with the excitation of an ion acoustic wave. We will study how
the dynamic ionosphere created auroral expansion.
The SP19 Chronology for the South Pole Ice Core – Part 1: Volcanic matching and annual-layer counting
Authors: Winski Dominic A. , Fudge Tyler J. , Ferris David G. , Osterberg Erich C. , Fegyveresi John M. , Cole-Dai Jihong , Thundercloud Zayta , Cox Thomas S. , Kreutz Karl J. , Ortman Nikolas , Buizert Christo , Epifanio Jenna , Brook Edward J. , Beaudette Ross , Severinghaus Jeff , Sowers Todd , Steig Eric J. , Kahle Emma C. , Jones Tyler R. , Morris Valerie , Aydin Murat , Nicewonger Melinda R. , Casey Kimberley A. , Alley Richard B. , Waddington Edwin D. , Iverson Nels A. , Bay Ryan C. , Souney Joseph M.
Published: June 2019

Abstract. The South Pole Ice Core (SPICEcore) was drilled in 2014–2016 to provide a detailed multi-proxy archive of paleoclimate conditions in East Antarctica during the Holocene and late Pleistocene. Interpretation of these records requires an accurate depth-age relationship. Here, we present the SP19 timescale for the age of the ice of SPICEcore. SP19 is synchronized to the WD2014 chronology from the West Antarctic Ice Sheet Divide (WAIS Divide) ice core using stratigraphic matching of 251 volcanic events. These events indicate an age of 54 302 ± 519 years BP (before the year 1950) at the bottom of SPICEcore. Annual layers identified in sodium and magnesium ions to 11 341 BP were used to interpolate between stratigraphic volcanic tie points, yielding an annually-resolved chronology through the Holocene. Estimated timescale uncertainty during the Holocene is less than 18 years relative to WD2014, with the exception of the interval between 1800 to 3100 BP when uncertainty estimates reach ± 25 years due to widely spaced volcanic tie points. Prior to the Holocene, uncertainties remain within 124 years relative to WD2014. Results show an average Holocene accumulation rate of 7.4 cm/yr (water equivalent). The time variability of accumulation rate is consistent with expectations for steady-state ice flow through the modern spatial pattern of accumulation rate. Time variations in nitrate concentration, nitrate seasonal amplitude, and δ15N of N2 in turn are as expected for the accumulation-rate variations. The highly variable yet well-constrained Holocene accumulation history at the site can help improve scientific understanding of deposition-sensitive climate proxies such as δ15N of N2 and photolyzed chemical compounds.
A near-surface sea temperature time series from Trieste, northern Adriatic Sea (1899–2015)
Authors: Raicich Fabio , Colucci Renato R.
Published: June 2019

Abstract. A time series of near-surface sea temperature was built from observations
performed in the harbour of Trieste from 14 July 1899 to 31 December 2015.
The description of the observation sites and instruments was possible thanks
to historical documents. The measurements consist of two data sets: the first
consists of analogue data obtained by means of thermometer and thermograph measurements, recorded one or two times per day, in the periods 1899–1923 and 1934–2008; the
second consists of digital records obtained by thermistors on an hourly basis in
the period 1986–2015. A quasi-homogeneous time series of daily temperatures
at 2 m depth is formed from direct observations at that depth and from
temperatures estimated from observations at shallower depths. From this time
series a mean temperature rise rate of 1.1±0.3 ∘C per century
was estimated, while in 1946–2015 it is 1.3±0.5 ∘C per
century. The data are available through SEANOE (https://doi.org/10.17882/58728; Raicich
and Colucci, 2019).
Stepwise chemical abrasion ID-TIMS-TEA of microfractured Hadean zircon
Authors: Keller C. Brenhin , Boehnke Patrick , Schoene Blair , Harrison T. Mark
Published: June 2019

Abstract. The Hadean Jack Hills zircons represent the oldest known terrestrial material, providing a unique and truly direct record of Hadean Earth history. This zircon population has been extensively studied via high spatial resolution, high throughput in situ isotopic and elemental analysis techniques such as secondary ionization mass spectrometry (SIMS), but not by comparatively destructive, high-temporal-precision (
An extended trajectory-mechanics approach for calculating the path of a pressure transient: Hydraulic tomographic imaging
Authors: Vasco Donald W. , Doetsch Joseph , Brauchler Ralf
Published: June 2019

Abstract. The application of a technique from quantum dynamics to the governing equation for hydraulic head leads to a trajectory-based solution that is valid for a general porous medium. The semi-analytic expressions for head propagation velocity and the propagation path form the basis of a hydraulic traveltime tomographic imaging algorithm. An application of the imaging algorithm to synthetic arrival times reveals that a crosswell inversion based upon the extended trajectories correctly reproduces the magnitude of a reference model, improving upon an existing asymptotic approach. An inversion of hydraulic head arrival times from crosswell slug tests at the Widen field site in northern Switzerland captures a general decrease in permeability with depth, in agreement with previous studies, but also indicates the presence of a high permeability feature in the upper portion of the crosswell plane.
INTEGRATION OF A LOW-COST MULTISENSORY UAV SYSTEM FOR FOREST APPLICATION
Authors: Li J. , Yang B. , Cong Y. , Li S. , Yue Y.
Published: June 2019

Abstract. To integrate the multi-spectral imagery and laser scanning data for forest management, a low-cost multisensory UAV system, named Kylin Cloud, is introduced in this paper. The Kylin Cloud is composed several low-cost sensors (i.e., GNSS receiver, IMU, global shutter camera, multispectral camera, and laser scanner), providing the fusion of the imagery and laser scanning data for reliable forest inventory. Experiments were undertaken in a forest park in Wuhan. Results showed that the registration error of the multispectral Digital Orthophoto Map (DOM) and laser scanning data is about one pixel, demonstrating a high potential of the proposed low-cost system.
CLUSTERING TIME SERIES OF REPEATED SCAN DATA OF SANDY BEACHES
Authors: Lindenbergh R. , van der Kleij S. , Kuschnerus M. , Vos S. , de Vries S.
Published: June 2019

Abstract. Sandy beaches are highly dynamic areas affected by different natural and anthropogenic effects. Large changes, caused by a storm for example, are in general well-understood and easy to measure. Most times, only small changes, at the centimeter scale, are occurring, but these changes accumulate significantly over periods from weeks to months. Laser scanning is a suitable technique to measure such small signals, as it is able to obtain dense 3D terrain data at centimeter level in a time span of minutes. In this work we consider two repeated laser scan data sets of two different beaches in The Netherlands. The first data set is from around the year 2000 and consists of six consecutive yearly airborne laser scan data sets of a beach on Texel. The second data set is from 2017 and consists of 30 consecutive daily terrestrial scans of a beach near The Hague. So far, little work has been done on time series analysis of repeated scan data. To obtain a first grouping of morphologic processes, we propose to use a simple un-supervised clustering approach, k-means clustering, on de-leveled, cumulative point-wise time series. The results for both regions of interest, obtained using k=5 and k=10 clusters, indicate that such clustering gives a meaningful decomposition of the morphological laser scan data into clusters that exhibit similar change patterns. At the same time, we realize that the chosen approach is just a first step in a wide open topic of clustering spatially correlated long time series of morphological laser scan data as are now obtained by permanent laser scanning.
AUTOMATIC ROAD STRUCTURE DETECTION AND VECTORIZATION USING MLS POINT CLOUDS
Authors: Mi X. , Yang B. , Chen C. , Yang M. , Dong Z.
Published: June 2019

Abstract. Accurate three-dimensional road structures and models are of great significance to intelligent transportation applications, such as vehicle navigation, inventory evaluation, construction quality control, self-driving vehicles and so on. This paper proposes an efficient and robust method to automatically extract structured road curbs from mobile laser scanning (MLS) data. The proposed method mainly consists of three steps: efficient supervoxel generation, road curbs detection and driving free space estimation. First, supervoxels are generated by assigning ground points with similar geometrical characteristics into the same group. Second, supervoxels with higher local projection density and height difference are identified and clustered as initial road curbs, which are continuous vertical curb facets. The continuous facades consisting of lots of scanned points on the road shoulder can be modeled as multi-dimensional boundary models depending on the requirements of the application, such as vector lines with or without height, micro-facades, etc. Finally, driving free space is obtained due to the road limits can be defined by road boundary in most scenarios. The proposed method is tested on two complex datasets acquired by an Alpha3D mobile laser scanning system from the urban area of Shanghai, China. Experimental results show that the road boundaries and driving free space can be accurately and efficiently extracted, which also demonstrates the superiority of the proposed method.
AUTOMATIC ROAD MARKINGS EXTRACTION, CLASSIFICATION AND VECTORIZATION FROM MOBILE LASER SCANNING DATA
Authors: Pan Y. , Yang B. , Li S. , Yang H. , Dong Z. , Yang X.
Published: June 2019

Abstract. To meet the demands of various applications such as high definition navigation map production for unmanned vehicles and road reconstruction and expansion engineering, this paper proposes an effective and efficient approach to automatically extract, classify and vectorize road markings from Mobile Laser Scanning (MLS) point clouds. Firstly, the MLS point cloud is segmented to ground and non-ground points. Secondly, several geo-reference images are generated and further used to detect road markings pixels under an image processing scheme. Thirdly, road marking point clouds are retrieved from the image and further segmented into connected objects. Otsu thresholding and Statistic Outlier Remover are adopted to refine the road marking objects. Next, each road marking objects are classified into several categories such as boundary lines, rectangle road markings, etc. based on its bounding box information. Other irregular road markings are classified by a model matching scheme. Finally, all classified road markings are vectorized as closed or unclosed polylines after reconnecting the breaking boundary lines. Comprehensive experiments are done on various MLS point clouds of both the urban and highway scenarios, which show that the precision and recall of the proposed method is higher than 95% for road marking extraction and as high as 93% for road marking classification on highway scenarios. The ratio is 92% and 85% for urban scenarios.
EVALUATING THE POSSIBILITY OF TREE SPECIES CLASSIFICATION WITH DUAL-WAVELENGTH ALS DATA
Authors: Pilarska M. , Ostrowski W.
Published: June 2019

Abstract. Airborne laser scanning (ALS) plays an important role in spatial data acquisition. One of the advantages of this technique is laser beam penetration through vegetation, which makes it possible to not only obtain data on the tree canopy but also within and under the canopy. In recent years, multi-wavelength airborne laser scanning has been developed. This technique consists of simultaneous acquisition of point clouds in more than one band. The aim of this experiment was to examine and assess the possibilities of tree segmentation and species classification in an urban area. In this experiment, point clouds registered in two wavelengths (532 and 1064 nm) were used for tree segmentation and species classification. The data were acquired with a Riegl VQ-1560i-DW laser scanner over Elblag, Poland, during August 2018. Tree species collected by a botanist team within terrain measurements were used as a reference in the classification process. Within the experiment segmentation and classification process were performed. Regarding the segmentation, TerraScan software and Li et al.’s algorithm, implemented in LidR package were used. Results from both methods are clearly over-segmented in comparison to the manual segments. In Terrasolid segmentation, single reference segments are over-segmented in 28% of cases, whereas, for LidR, over-segmentation occurred in 73% of the segments. According the classification results, Thuja, Salix and Betula were the species, for which the highest classification accuracy was achieved.
AUTOMATIC DETECTION OF ROAD EDGES FROM AERIAL LASER SCANNING DATA
Authors: Truong-Hong L. , Laefer D. F. , Lindenbergh R. C.
Published: June 2019

Abstract. When aerial laser scanning (ALS) is deployed with targeted flight path planning, urban scenes can be captured in points clouds with both high vertical and horizontal densities to support a new generation of urban analysis and applications. As an example, this paper proposes a hierarchical method to automatically extract data points describing road edges, which are then used for reconstructing road edges and identifying accessible passage areas. The proposed approach is a cell-based method consisting of 3 main steps: (1) filtering rough ground points, (2) extracting cells containing data points of the road curb, and (3) eliminating incorrect road curb segments. The method was tested on a pair of 100 m × 100 m tiles of ALS data of Dublin Ireland’s city center with a horizontal point density of about 325 points/m2. Results showed the data points of the road edges to be extracted properly for locations appearing as the road edges with the average distance errors of 0.07 m and the ratio between the extracted road edges and the ground truth by 73.2%.
TLS POINT CLOUD REGISTRATION FOR DETECTING CHANGE IN INDIVIDUAL ROCKS OF A MOUNTAIN RIVER BED
Authors: Walicka A. , Pfeifer N. , Jóźków G. , Borkowski A.
Published: June 2019

Abstract. Remote sensing techniques are an important tool in fluvial transport monitoring, since they allow for effective evaluation of the volume of transported material. Nevertheless, there is no methodology for automatic calculation of movement parameters of individual rocks. These parameters can be determined by point cloud registration. Hence, the goal of this study is to develop a robust algorithm for terrestrial laser scanning point cloud registration. The registration is based on Iterative Closest Point algorithm, which requires well established initial parameters of transformation. Thus, we propose to calculate the initial parameters based on key points representing the maximum of Gaussian curvature. For each key point the set of geometrical features is calculated. The key points are then matched between two point clouds as a nearest neighbor in feature domain. Different combinations of neighborhood sizes, feature subsets, metrics and number of nearest neighbors were tested to obtain the highest ratio between properly and improperly matched key points. Finally, RANSAC algorithm was used to calculate the initial transformation parameters between the point clouds and the ICP algorithm was used for calculation of final transformation parameters. The investigations carried out on sample point clouds representing rocks enabled the adjustment of parameters of the algorithm and showed that the Gaussian curvature can be used as a 3-dimentional key point detector for such objects. The proposed algorithm enabled to register point clouds with the mean distance between point clouds equal to 3 mm.
LOW-COST WHEELED ROBOT-BORNE LASER SCANNING SYSTEM FOR INDOOR AND OUTDOOR 3D MAPPING APPLICATION
Authors: Wu W. , Chen C. , Cong Y. , Dong Z. , Li J. , Li S. , Dai W. , Yang B.
Published: June 2019

Abstract. Aiming to accomplish automatic and real-time three-dimensional mapping in both indoor and outdoor scenes, a low-cost wheeled robot-borne laser scanning system is proposed in this paper. The system includes a laser scanner, an inertial measurement unit, a modified turtlebot3 two-wheel differential chassis and etc. To achieve a globally consistent map, the system performs global trajectory optimization after detecting the loop closure. Experiments are undertaken in two typical indoor/outdoor scenes that is an underground car park and a road environment in the campus of Wuhan University. The point clouds acquired by the proposed system are quantitatively evaluated by comparing the derived point clouds with the ground truth data collected by a RIEGL VZ 400 laser scanner. The results present an accuracy of 90% points below 0.1 meter error in the tested scene, showing that its applicability and potential in indoor and mapping applications.
EVALUATION AND CALIBRATION OF FIXED-WING MULTISENSOR UAV MOBILE MAPPING SYSTEM: IMPROVED RESULTS
Authors: Bakuła K. , Ostrowski W. , Pilarska M. , Szender M. , Kurczyński Z.
Published: June 2019

Abstract. Unmanned Aerial Vehicles (UAVs) are willingly used in photogrammetry and remote sensing, especially for image acquisition, and are characterised by high spatial resolution. UAVs can be used for the fast and, if necessary, frequent acquisition of spatial data, especially for small areas. In recent years, new trends in the development of UAVs have emerged, including the integration of various sensors and the application of ultralight laser scanners. Within the described experiment, UAV data, i.e. RGB and NIR imagery, as well as ALS data were obtained over three test areas. For one test area, the flight calibration was performed. 3 strips were oriented perpendicularly to another 3 strips and the flight was performed on two different heights: 120 and 150 m. In order to process the data acquired for the next 3 test areas, the determined calibration parameters were utilised. The oriented images were used to generate RGB and NIR ortophotos, as well as the point cloud using the Dense Image Matching (DIM) algorithm. Height differences between UAV Laser Scanning (ULS) and DIM clouds were calculated for all test areas. Experiment data from Terrestrial Laser Scanning and check points measured with GPS RTK have been used. Finally, an accuracy of less than 10 cm was achieved for the DTM. The results were improved by eliminating the problem of horizontal accuracy, but its influence is still slightly visible on the vertical accuracy of the data. The experiment proved the quality of data obtained with the ultralight scanner mounted on the platform moving with much more speed, being an alternative to manned flight missions and multi-rotors UAVs.
POTENTIAL OF NON-CALIBRATED UAV-BASED RGB IMAGERY FOR FORAGE MONITORING: CASE STUDY AT THE RENGEN LONG-TERM GRASSLAND EXPERIMENT (RGE), GERMANY
Authors: Bareth G. , Lussem U. , Menne J. , Hollberg J. , Schellberg J.
Published: June 2019

Abstract. Forage monitoring in grassland is an important task to support management decisions. Spatial data on (i) yield,(ii) quality, and (iii) floristic composition are of interest. The spatio-temporal variability in grasslands is significant and requires fast and low-cost methods for data delivery. Therefore, the overarching aim of this contribution is the investigation of low-cost and non-calibrated UAV-derived RGB imagery for forage monitoring. Study area is the Rengen Grassland Experiment (RGE) in Germany which is a long-term field experiment since 1941. Due to the experiment layout, destructive biomass sampling during the growing period was not possible. Hence, non-destructive Rising Plate Meter (RPM) measurements, which are a common method to estimate biomass in grasslands, were carried out. UAV campaigns with a Canon Powershot 110 mounted on a DJI Phantom 2 were conducted in the first growing season in 2014. From the RGB imagery, the RGB vegetation index (RGBVI) and the Grassland Index (GrassI) introduced by Bendig et al. (2015) and Bareth et al. (2015), respectively, were computed. The RGBVI and the GrassI perform very well against the RPM measurements resulting in R2 of 0.84 and 0.9, respectively. These results indicate the potential of low-cost UAV methods for grassland monitoring and correspond well to the studies of Viljanen et al. (2018) and Näsi et al. (2018).
RASPBERRY PI 3 MULTISPECTRAL LOW-COST SENSOR FOR UAV BASED REMOTE SENSING. CASE STUDY IN SOUTH-WEST NIGER
Authors: Belcore E. , Piras M. , Pezzoli A. , Massazza G. , Rosso M.
Published: June 2019

Abstract. The technology of UAV (Unmanned Aerial Vehicles) is rapidly improving and UAV-integrated sensors have kept up with it, providing more efficient and effective solutions. One of the most sought-after characteristics of on-board sensors is the low costing associated to good quality of the collected data. This paper proposes a very low-cost multiband sensor developed on a Raspberry device and two Raspberry Pi 3 cameras that can be used in photogrammetry from drone applications. The UAV-integrated radiometric sensor and its performance were tested in in two villages of South-west Niger for the detection of temporary surface water bodies (or Ephemeral water bodies): zones of seasonal stagnant water within villages threatening the viability and people’s health. The Raspberry Pi 3 cameras employed were a regular RGB Pi camera 2 (Red, Green, Blue) and a NoIR Pi 3 camera v2 (regular RGB without IR filter) with 8MPX resolution. The cameras were geometrically calibrated and radiometrically tested before the survey in the field. The results of the photogrammetry elaborations were 4 orthophotos (a RGB and NoIRGB orthophoto for each village). The Normalized Difference Water Index (NDWI) was calculated. The index allowed the localization and the contouring of the temporary surface water bodies present in the villages. The data were checked against the data collected with a Sony (ILCE-5100). Very high correspondence between the different data was detected. Raspberry-based sensors demonstrated to be a valid tool for the data collection in critical areas.
ACTIVE SHAPE MODEL PRECISION ANALYSIS OF VEHICLE DETECTION IN 3D LIDAR POINT CLOUDS
Authors: Busch S.
Published: June 2019

Abstract. LiDAR systems are frequently used for driver assistance systems. The minimal distance to other objects and the exact pose of a vehicle is important for ego movement prediction. Therefore, in this work, we extract the poses of vehicles from LiDAR point clouds. To this end, we measure them with LiDAR, segment the vehicle points and extract the pose. Further, we analyze the influence of LiDAR resolutions on the pose extraction by active shape models (ASM) and by the center of bounding boxes combined with the principal component analysis (BC-PCA).
AIRBORNE TO UAS LIDAR: AN ANALYSIS OF UAS LIDAR GROUND CONTROL TARGETS
Authors: Davidson L. , Mills J. P. , Haynes I. , Augarde C. , Bryan P. , Douglas M.
Published: June 2019

Abstract. Creating accurate models of the Earth’s surface is an essential step when analysing geomorphological changes through time. Alongside photogrammetry, airborne lidar is an established method for measuring and modelling the Earth’s surface. However, improvements in size, weight and power requirements mean that lidar is now increasingly capable of being operated from Unpiloted Aircraft Systems (UASs). While academic literature is currently weighted towards issues associated with airborne laser scanning, UASs operate under different parameters to piloted aeroplanes and helicopters. In order to achieve desired results from UAS lidar, mission planning parameters and ground control requirements therefore need to be tailored to data collection from UAS platforms. This paper presents the preliminary results of how a variety control target designs responded to a UAS lidar survey flown along different trajectories at different heights above ground level. This research draws upon previous airborne laser scanning work and aims to provide guidance on considerations for UAS lidar specific ground control targets.