Influence of length on acoustic time-of-flight (ToF) measurement in built-in structures of Norway spruce timber

Holzforschung ◽  
2019 ◽  
Vol 73 (4) ◽  
pp. 339-352 ◽  
Author(s):  
Francisco Arriaga ◽  
Joaquín Montón ◽  
Ignacio Bobadilla ◽  
Daniel F. Llana
Keyword(s):  
Norway Spruce ◽  
Time Lag ◽  
Time Of Flight ◽  
Distance Estimation ◽  
Modulus Of Rupture ◽  
Surface Velocity ◽  
Apparent Velocity ◽  
Distance Measurements ◽  
Predictive Capacity ◽  
End To End

AbstractTime-of-flight (ToF) measurements were conducted on twelve 76×226-mm2in cross-section, 4.52-m long specimens of Norway spruce timber pieces from a dismantled 19th-century building in Barcelona (Catalonia, Spain). Two commercially available acoustic devices were used: the USLab ultrasound device with conical 22 and 45 kHz sensors and the MicroSecond Timer (MST) stress wave device with spike sensors. ToF were obtained for the full-length (4.52 m) specimens in an end-to-end arrangement and for lengths of 0.5, 1, 1.5, 2, 3 and 4 m on the same surface and on opposite surfaces. The differences between the velocities obtained from end-to-end and semi-direct measurements were less than 4.5%. Apparent velocity dependence on length was observed in short-distance measurements. This could be corrected by determining a time lag (tL) from a linear regression between the ToF and the distance. Estimation of the modulus of elasticity (MOE) from the dynamic MOE (MOEdyn) is acceptable (r2=0.45–0.69) depending on the measurement procedure, and the best results forin situtimber are obtained in edge surface velocity. Although modulus of rupture (MOR) estimation from MOEdynimproves slightly when knottiness is included, it has low predictive capacity.

Influence of length and sensor positioning on acoustic time-of-flight (ToF) measurement in structural timber

Holzforschung ◽  
2017 ◽  
Vol 71 (9) ◽  
pp. 713-723 ◽  
Author(s):  
Francisco Arriaga ◽  
Daniel F. Llana ◽  
Miguel Esteban ◽  
Guillermo Íñiguez-González
Keyword(s):  
Time Lag ◽  
Time Of Flight ◽  
Radiata Pine ◽  
Apparent Velocity ◽  
Longitudinal Measurements ◽  
Dependent Property ◽  
Length Determination ◽  
End To End ◽  
Sensor Positioning

Abstract The mechanical properties of timber can be estimated from wave propagation velocity by measuring wave time-of-flight (ToF). However, a time-lag complicates the measurements, which produces an apparent velocity dependency on length and this species and instrument dependent property is also influenced by knottiness. This research is dealing with time-lag determination by different sensor positioning in situ ToF measurements. ToF longitudinal measurements were conducted on 120 90 mm×140 mm specimens of the coniferous species radiata pine, Scots pine, laricio pine and maritime pine. The following commercially available acoustic devices were used: Sylvatest Duo, USLab, and Microsecond Timer. The sensors were arranged for the measurement types “end-to-end”, “on the same surface” and “on opposite surfaces”. ToF data were obtained from the full-length (4 m) specimens and then from the same specimens shortened to 3 m, 2 m and 1 m in length. The in situ procedures of ToF are applicable for a reliable length determination independently from the time-lag (tL) and velocity. The differences observed by end-to-end measurements, with respect to velocity, are below 4.4%. A velocity correction factor can be deduced for each instrument, which is independent of species.

scholarly journals End-to-end recognition of streaming Japanese speech using CTC and local attention

2020 ◽  
Vol 9 ◽  
Author(s):  
Jiahao Chen ◽  
Ryota Nishimura ◽  
Norihide Kitaoka
Keyword(s):  
Speech Recognition ◽  
Recognition Performance ◽  
Time Lag ◽  
Recognition Algorithm ◽  
Streaming Data ◽  
Continuous Speech Recognition ◽  
Voice Input ◽  
Sequence Modeling ◽  
End To End ◽  
Bidirectional Networks

Many end-to-end, large vocabulary, continuous speech recognition systems are now able to achieve better speech recognition performance than conventional systems. Most of these approaches are based on bidirectional networks and sequence-to-sequence modeling however, so automatic speech recognition (ASR) systems using such techniques need to wait for an entire segment of voice input to be entered before they can begin processing the data, resulting in a lengthy time-lag, which can be a serious drawback in some applications. An obvious solution to this problem is to develop a speech recognition algorithm capable of processing streaming data. Therefore, in this paper we explore the possibility of a streaming, online, ASR system for Japanese using a model based on unidirectional LSTMs trained using connectionist temporal classification (CTC) criteria, with local attention. Such an approach has not been well investigated for use with Japanese, as most Japanese-language ASR systems employ bidirectional networks. The best result for our proposed system during experimental evaluation was a character error rate of 9.87%.

scholarly journals Time since death and decay rate constants of Norway spruce and European larch deadwood in subalpine forests determined using dendrochronology and radiocarbon dating

2016 ◽  
Vol 13 (5) ◽  
pp. 1537-1552 ◽  
Author(s):  
Marta Petrillo ◽  
Paolo Cherubini ◽  
Giulia Fravolini ◽  
Marco Marchetti ◽  
Judith Ascher-Jenull ◽  
...  
Keyword(s):  
Picea Abies ◽  
Decay Rate ◽  
Norway Spruce ◽  
Matrix Model ◽  
Rate Constants ◽  
Radiocarbon Dating ◽  
Time Lag ◽  
Larix Decidua ◽  
European Larch ◽  
14C Dating

Abstract. Due to the large size (e.g. sections of tree trunks) and highly heterogeneous spatial distribution of deadwood, the timescales involved in the coarse woody debris (CWD) decay of Picea abies (L.) Karst. and Larix decidua Mill. in Alpine forests are largely unknown. We investigated the CWD decay dynamics in an Alpine valley in Italy using the chronosequence approach and the five-decay class system that is based on a macromorphological assessment. For the decay classes 1–3, most of the dendrochronological samples were cross-dated to assess the time that had elapsed since tree death, but for decay classes 4 and 5 (poorly preserved tree rings) radiocarbon dating was used. In addition, density, cellulose, and lignin data were measured for the dated CWD. The decay rate constants for spruce and larch were estimated on the basis of the density loss using a single negative exponential model, a regression approach, and the stage-based matrix model. In the decay classes 1–3, the ages of the CWD were similar and varied between 1 and 54 years for spruce and 3 and 40 years for larch, with no significant differences between the classes; classes 1–3 are therefore not indicative of deadwood age. This seems to be due to a time lag between the death of a standing tree and its contact with the soil. We found distinct tree-species-specific differences in decay classes 4 and 5, with larch CWD reaching an average age of 210 years in class 5 and spruce only 77 years. The mean CWD rate constants were estimated to be in the range 0.018 to 0.022 y−1 for spruce and to about 0.012 y−1 for larch. Snapshot sampling (chronosequences) may overestimate the age and mean residence time of CWD. No sampling bias was, however, detectable using the stage-based matrix model. Cellulose and lignin time trends could be derived on the basis of the ages of the CWD. The half-lives for cellulose were 21 years for spruce and 50 years for larch. The half-life of lignin is considerably higher and may be more than 100 years in larch CWD. Consequently, the decay of Picea abies and Larix decidua is very low. Several uncertainties, however, remain: 14C dating of CWD from decay classes 4 and 5 and having a pre-bomb age is often difficult (large age range due to methodological constraints) and fall rates of both European larch and Norway spruce are missing.

scholarly journals River ice flux and water velocities along a 600 km long reach of Lena River, Siberia, from satellite stereo

2013 ◽  
Vol 10 (7) ◽  
pp. 9967-9997 ◽  
Author(s):  
A. Kääb ◽  
M. Lamare ◽  
M. Abrams
Keyword(s):  
River Flow ◽  
Thermal Emission ◽  
Time Lag ◽  
Open Water ◽  
Image Resolution ◽  
Surface Velocity ◽  
River Ice ◽  
Data Set ◽  
Hazard Management ◽  
Lena River

Abstract. Knowledge of water-surface velocities in rivers is useful for understanding a range of river processes. In cold regions, river-ice break up and the related downstream transport of ice debris is often the most important hydrological event of the year, leading to flood levels that typically exceed those for the open-water period and to strong consequences for river infrastructure and ecology. Accurate and complete surface-velocity fields on rivers have rarely been produced. Here, we track river ice debris over a time period of about one minute, which is the typical time lag between the two or more images that form a stereo data set in spaceborne, along-track optical stereo-mapping. Using a series of 9 stereo scenes from the US/Japanese Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) onboard the NASA Terra spacecraft with 15 m image resolution, we measure the ice and water velocity field over a 620 km long reach of the lower Lena River, Siberia, just above its entry into the Lena delta. Careful analysis and correction of higher-order image and sensor errors enables an accuracy of ice-debris velocities of up to 0.04 m s−1 from the ASTER data. Maximum ice or water speeds, respectively, reach up to 2.5 m s−1 at the time of data acquisition, 27 May 2011 (03:30 UTC). Speeds show clear along-stream undulations with a wavelength of about 21 km that agree well with variations in channel width and with the location of sand bars along the river reach studied. The methodology and results of this study could be valuable to a number of disciplines requiring detailed information about river flow, such as hydraulics, hydrology, river ecology and natural-hazard management.

scholarly journals Climate-sensitive radial increment model of Norway spruce in Tyrol based on a distributed lag model with penalized splines for year-ring time series

2018 ◽  
Vol 48 (8) ◽  
pp. 930-941 ◽  
Author(s):  
Arne Nothdurft ◽  
Sonja Vospernik
Keyword(s):  
Time Series ◽  
Norway Spruce ◽  
High Temperatures ◽  
Time Lag ◽  
Ring Width ◽  
Penalized Regression ◽  
Penalized Splines ◽  
Radial Increment ◽  
Model Framework ◽  
Lag Model

A novel methodological framework is presented for climate-sensitive modeling of annual radial stem increment using year-ring width time series. The approach is based on a generalized additive model with penalized regression splines together with a distributed time lag model taking into account smooth nonlinear effects of a series of monthly temperature and precipitation values, as well as their interactions. Climate effects are also assumed to vary smoothly with time lag. The model framework enables both the detrending of the individual time series and the regression modeling to be performed simultaneously in a single model step. The approach is applied to year-ring width time series of Norway spruce (Picea abies (L.) H. Karst.) trees in Tyrol, Austria. The marginal response curves show that tree growth is mainly promoted by high temperatures in late spring and early summer and by precipitation in fall and winter. Summer drought does not have a negative influence on the current year’s radial increment; however, when it is associated with high temperatures, it lowers the increment in the subsequent growth period. Higher winter precipitation in conjunction with lower temperatures has a positive effect. A significant non-climate related long-term growth trend is demonstrated, probably reflecting NOx and SO2 emission trends in Austria.

scholarly journals Loop Current Variability as Trigger of Coherent Gulf Stream Transport Anomalies

2019 ◽  
Vol 49 (8) ◽  
pp. 2115-2132 ◽  
Author(s):  
Joël J.-M. Hirschi ◽  
Eleanor Frajka-Williams ◽  
Adam T. Blaker ◽  
Bablu Sinha ◽  
Andrew Coward ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Gulf Stream ◽  
Time Lag ◽  
Ocean Model ◽  
Surface Velocity ◽  
Loop Current ◽  
Intrinsic Variability ◽  
Cape Hatteras ◽  
Florida Straits ◽  
Stream Transport

AbstractSatellite observations and output from a high-resolution ocean model are used to investigate how the Loop Current in the Gulf of Mexico affects the Gulf Stream transport through the Florida Straits. We find that the expansion (contraction) of the Loop Current leads to lower (higher) transports through the Straits of Florida. The associated surface velocity anomalies are coherent from the southwestern tip of Florida to Cape Hatteras. A simple continuity-based argument can be used to explain the link between the Loop Current and the downstream Gulf Stream transport: as the Loop Current lengthens (shortens) its path in the Gulf of Mexico, the flow out of the Gulf decreases (increases). Anomalies in the surface velocity field are first seen to the southwest of Florida and within 4 weeks propagate through the Florida Straits up to Cape Hatteras and into the Gulf Stream Extension. In both the observations and the model this propagation can be seen as pulses in the surface velocities. We estimate that the Loop Current variability can be linked to a variability of several Sverdrups (1Sv = 106 m3 s−1) through the Florida Straits. The exact timing of the Loop Current variability is largely unpredictable beyond a few weeks and its variability is therefore likely a major contributor to the chaotic/intrinsic variability of the Gulf Stream. However, the time lag between the Loop Current and the flow downstream of the Gulf of Mexico means that if a lengthening/shortening of the Loop Current is observed this introduces some predictability in the downstream flow for a few weeks.

scholarly journals River ice flux and water velocities along a 600 km-long reach of Lena River, Siberia, from satellite stereo

2013 ◽  
Vol 17 (11) ◽  
pp. 4671-4683 ◽  
Author(s):  
A. Kääb ◽  
M. Lamare ◽  
M. Abrams
Keyword(s):  
River Flow ◽  
Thermal Emission ◽  
Time Lag ◽  
Open Water ◽  
Image Resolution ◽  
Surface Velocity ◽  
River Ice ◽  
Data Set ◽  
Hazard Management ◽  
Lena River

Abstract. Knowledge of water-surface velocities in rivers is useful for understanding a range of river processes. In cold regions, river-ice break up and the related downstream transport of ice debris is often the most important hydrological event of the year, leading to flood levels that typically exceed those for the open-water period and to strong consequences for river infrastructure and ecology. Accurate and complete surface-velocity fields on rivers have rarely been produced. Here, we track river ice debris over a time period of about one minute, which is the typical time lag between the two or more images that form a stereo data set in spaceborne, along-track optical stereo mapping. Using a series of nine stereo scenes from the US/Japanese Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) onboard the NASA Terra spacecraft with 15 m image resolution, we measure the ice and water velocity field over a 620 km-long reach of the lower Lena River, Siberia, just above its entry into the Lena delta. Careful analysis and correction of higher-order image and sensor errors enables an accuracy of ice-debris velocities of up to 0.04 m s−1 from the ASTER data. Maximum ice or water speeds, respectively, reach up to 2.5 m s−1 at the time of data acquisition, 27 May 2011 (03:30 UTC). Speeds show clear along-stream undulations with a wavelength of about 21 km that agree well with variations in channel width and with the location of sand bars along the river reach studied. The methodology and results of this study could be valuable to a number of disciplines requiring detailed information about river flow, such as hydraulics, hydrology, river ecology and natural-hazard management.

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