scholarly journals LiDAR DEM Smoothing and the Preservation of Drainage Features

2019 ◽  
Vol 11 (16) ◽  
pp. 1926 ◽  
Author(s):  
John B. Lindsay ◽  
Anthony Francioni ◽  
Jaclyn M. H. Cockburn
Keyword(s):  
Headwater Streams ◽  
Three Dimensional ◽  
Surface Flow ◽  
Lidar Data ◽  
Near Surface ◽  
Topographic Complexity ◽  
Smoothing Methods ◽  
Low Pass ◽  
Lidar Dem ◽  
Low Pass Filters

Fine-resolution Light Detection and Ranging (LiDAR) data often exhibit excessive surface roughness that can hinder the characterization of topographic shape and the modeling of near-surface flow processes. Digital elevation model (DEM) smoothing methods, commonly low-pass filters, are sometimes applied to LiDAR data to subdue the roughness. These techniques can negatively impact the representation of topographic features, most notably drainage features, such as headwater streams. This paper presents the feature-preserving DEM smoothing (FPDEMS) method, which modifies surface normals to smooth the topographic surface in a similar manner to approaches that were originally designed for de-noising three-dimensional (3D) meshes. The FPDEMS method has been optimized for application with raster DEM data. The method was compared with several low-pass filters while using a 0.5-m resolution LiDAR DEM of an agricultural area in southwestern Ontario, Canada. The findings demonstrated that the technique was better at removing roughness, when compared with mean, median, and Gaussian filters, while also preserving sharp breaks-in-slope and retaining the topographic complexity at broader scales. Optimal smoothing occurred with kernel sizes of 11–21 grid cells, threshold angles of 10°–20°, and 3–15 elevation-update iterations. These parameter settings allowed for the effective reduction in roughness and DEM noise and the retention of terrace scarps, channel banks, gullies, and headwater streams.

scholarly journals Cardiac myocyte microtissue aggregates broadcast local field potentials

2018 ◽  
Author(s):  
Mijail D. Serruya ◽  
Suradip Das ◽  
Kritika S. Katiyar ◽  
Laura A. Struzyna ◽  
Justin C. Burrell ◽  
...  
Keyword(s):  
Muscle Tissue ◽  
Cardiac Myocyte ◽  
Three Dimensional ◽  
Physical Contact ◽  
Limb Amputation ◽  
Field Potentials ◽  
Electrode Arrays ◽  
Low Pass ◽  
Spontaneous Contractions ◽  
Low Pass Filters

AbstractMuscle tissue has been exploited as a living biopotential amplifier to facilitate transduction of peripheral nerve signals into prosthetic control in patients with limb amputation. Here we sought to address the question of whether microscopically small volumes of muscle tissue could effectively broadcast field potentials to electrodes not immediately in contact with that tissue. Cardiac myocytes were grown as three-dimensional aggregates containing 105 cells comprising a volume of approximately 0.065 mm3 (~500 μm in diameter) atop multi-electrode arrays. In addition to the expected spontaneous contraction potentials detected using electrodes in direct contact with the myocytes, potentials could also be detected on distant electrodes not contacting the aggregates. Specifically, while both dissociated and aggregated cardiac myocyte cultures generated spontaneous contractions that could easily be recorded from underlying multi-electrode arrays, only aggregated myocyte cultures generated signals detectable several millimeters away by the electrode grid floating in media. This confirmed the ability of micro-volumes of aggregated muscle tissue to broadcast readily detectible signals. The amplitude of the potentials generated by the aggregates decreased exponentially with distance. The aggregates were sensitive to pharmacologic modification with isoproterenol increasing contraction rate. Simultaneous recordings with electrodes in physical contact to the aggregate and with electrodes several millimeters away revealed that the aggregates function as amplifiers and low-pass filters. This study lays the groundwork for forging myocyte aggregates as “living amplifiers” for long-term neural recording in brain-computer interfaces to treat neurological disease and injury.

scholarly journals Effective resolution concepts for lidar observations

2015 ◽  
Vol 8 (5) ◽  
pp. 5363-5424
Author(s):  
M. Iarlori ◽  
F. Madonna ◽  
V. Rizi ◽  
T. Trickl ◽  
A. Amodeo
Keyword(s):  
Digital Signal ◽  
High Spectral Resolution ◽  
Lidar Data ◽  
Vertical Profiles ◽  
Range Resolution ◽  
True Profile ◽  
Low Pass ◽  
Low Pass Filters ◽  
The Impact ◽  
Aerosol Properties

Abstract. Since its first establishment in 2000, EARLINET (European Aerosol Research Lidar NETwork) has been devoted to providing, through its database, exclusively quantitative aerosol properties, such as aerosol backscatter and aerosol extinction coefficients, the latter only for stations able to retrieve it independently (from Raman or High Spectral Resolution Lidars). As these coefficients are provided in terms of vertical profiles, EARLINET database must also include the details on the range resolution of the submitted data. In fact, the algorithms used in the lidar data analysis often alter the spectral content of the data, mainly working as low pass filters with the purpose of noise damping. Low pass filters are mathematically described by the Digital Signal Processing (DSP) theory as a convolution sum. As a consequence, this implies that each filter's output, at a given range (or time) in our case, will be the result of a linear combination of several lidar input data relative to different ranges (times) before and after the given range (time): a first hint of loss of resolution of the output signal. The application of filtering processes will also always distort the underlying true profile whose relevant features, like aerosol layers, will then be affected both in magnitude and in spatial extension. Thus, both the removal of noise and the spatial distortion of the true profile produce a reduction of the range resolution. This paper provides the determination of the effective resolution (ERes) of the vertical profiles of aerosol properties retrieved starting from lidar data. Large attention has been addressed to provide an assessment of the impact of low-pass filtering on the effective range resolution in the retrieval procedure.

scholarly journals In Situ, Doppler Radar, and Video Observations of the Interior Structure of a Tornado and the Wind–Damage Relationship

2013 ◽  
Vol 94 (6) ◽  
pp. 835-846 ◽  
Author(s):  
Joshua Wurman ◽  
Karen Kosiba ◽  
Paul Robinson
Keyword(s):  
Doppler Radar ◽  
Three Dimensional ◽  
Time History ◽  
Periodic Oscillation ◽  
Surface Flow ◽  
Near Surface ◽  
Direct Observations ◽  
Video Observations ◽  
History Of ◽  
Armored Vehicle

Direct observations of the winds inside a tornado were obtained with an instrumented armored vehicle, the Tornado Intercept Vehicle (TIV), and integrated with finescale mobile Doppler radar (Doppler on Wheels) data revealing, for the first time, the structure of the near-ground three-dimensional wind field in and around the core region of a strong tornado, and permitting comparison with conceptual models. Inward and upward spiraling near-surface flow, upward motion near the surface, and an axial downdraft aloft are documented, as well as a periodic oscillation in tornado intensity. Simultaneous video documentation of damage occurring during the tornado is related to the direct wind observations, permitting the first comparisons of the time history of damage to the time history of directly measured winds and a limited evaluation of the underlying assumptions and quantitative relationships in the enhanced Fujita (EF) scale.

scholarly journals Reconstruction of 3D Pavement Texture on Handling Dropouts and Spikes Using Multiple Data Processing Methods

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 278 ◽  
Author(s):  
Niya Dong ◽  
Jorge Prozzi ◽  
Fujian Ni
Keyword(s):  
Interpolation Method ◽  
Three Dimensional ◽  
Rolling Resistance ◽  
Baseline Length ◽  
Laser Sensor ◽  
Texture Measurement ◽  
Multiple Data ◽  
Low Pass ◽  
Low Pass Filters ◽  
The Impact

Tire–pavement interactions, like friction and rolling resistance, are significantly influenced by pavement macro-texture and micro-texture. Accurate texture measurement at the micro-texture level is vital to achieve the desired level of safety, comfort, and sustainability of the pavement. However, the existence of dropouts and spikes in the collected data is still inevitable based on current laser devices, which leads to erroneous texture characterization. This study utilized an advanced laser sensor to measure three-dimensional (3D) pavement texture at the micro-level at a given speed. Using a proposed interpolation method, the dropout areas in the raw measurements were filled up. Butterworth’s high-pass and low-pass filters were applied to separate two texture components from the profile. Based on a statistical analysis for the micro-texture amplitude, an appropriate threshold was determined in order to identify the spikes. A three-step-spike-removal method was proposed and found to be effective in clearing the spikes. The 3D pavement profiles were finally reconstructed without dropouts and spikes. Mean profile depth (MPD) was calculated with different baselines. It was found that the presence of spikes leads to a greater MPD value and the MPD is sensitive to the baseline length. A shorter baseline is recommended to mitigate the impact of spikes on the accuracy of the MPD.

Ku/Ka-band Compact Orthomode Junction with Low Pass Filters for High Power Applications

2015 ◽  
Vol E98.C (2) ◽  
pp. 156-161
Author(s):  
Hidenori YUKAWA ◽  
Koji YOSHIDA ◽  
Tomohiro MIZUNO ◽  
Tetsu OWADA ◽  
Moriyasu MIYAZAKI
Keyword(s):  
High Power ◽  
Ka Band ◽  
Low Pass ◽  
Low Pass Filters

Mathematical Model of Low-Pass Filters

2011 ◽  
Vol 5 (2) ◽  
pp. 155-162
Author(s):  
Jose de Jesus Rubio ◽  
Diana M. Vazquez ◽  
Jaime Pacheco ◽  
Vicente Garcia
Keyword(s):  
Mathematical Model ◽  
Low Pass ◽  
Low Pass Filters

scholarly journals Delay Equivalences in Tuning PID Control for the Double Integrator Plus Dead-Time

Mathematics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 328
Author(s):  
Mikulas Huba ◽  
Damir Vrancic
Keyword(s):  
Dead Time ◽  
Pid Controllers ◽  
Noisy Environment ◽  
Advantages And Disadvantages ◽  
Implementation Problem ◽  
Low Pass ◽  
Excellent Control ◽  
Low Pass Filters ◽  
Double Integrator

The paper investigates and explains a new simple analytical tuning of proportional-integrative-derivative (PID) controllers. In combination with nth order series binomial low-pass filters, they are to be applied to the double-integrator-plus-dead-time (DIPDT) plant models. With respect to the use of derivatives, it should be understood that the design of appropriate filters is not only an implementation problem. Rather, it is also critical for the resulting performance, robustness and noise attenuation. To simplify controller commissioning, integrated tuning procedures (ITPs) based on three different concepts of filter delay equivalences are presented. For simultaneous determination of controller + filter parameters, the design uses the multiple real dominant poles method. The excellent control loop performance in a noisy environment and the specific advantages and disadvantages of the resulting equivalences are discussed. The results show that none of them is globally optimal. Each of them is advantageous only for certain noise levels and the desired degree of their filtering.

Thermomechanical Coupling of a Hyper-viscoelastic Truck Tire and a Pavement Layer and its Impact on Three-dimensional Contact Stresses

2021 ◽  
pp. 036119812110171
Author(s):  
Angeli Jayme ◽  
Imad L. Al-Qadi
Keyword(s):  
Contact Stress ◽  
Contact Area ◽  
Three Dimensional ◽  
Interaction Model ◽  
Rolling Resistance ◽  
Contact Stresses ◽  
Thermomechanical Coupling ◽  
Temperature Profiles ◽  
Near Surface ◽  
Truck Tire

A thermomechanical coupling between a hyper-viscoelastic tire and a representative pavement layer was conducted to assess the effect of various temperature profiles on the mechanical behavior of a rolling truck tire. The two deformable bodies, namely the tire and pavement layer, were subjected to steady-state-uniform and non-uniform temperature profiles to identify the significance of considering temperature as a variable in contact-stress prediction. A myriad of ambient, internal air, and pavement-surface conditions were simulated, along with combinations of applied tire load, tire-inflation pressure, and traveling speed. Analogous to winter, the low temperature profiles induced a smaller tire-pavement contact area that resulted in stress localization. On the other hand, under high temperature conditions during the summer, higher tire deformation resulted in lower contact-stress magnitudes owing to an increase in the tire-pavement contact area. In both conditions, vertical and longitudinal contact stresses are impacted, while transverse contact stresses are relatively less affected. This behavior, however, may change under a non-free-rolling condition, such as braking, accelerating, and cornering. By incorporating temperature into the tire-pavement interaction model, changes in the magnitude and distribution of the three-dimensional contact stresses were manifested. This would have a direct implication on the rolling resistance and near-surface behavior of flexible pavements.

scholarly journals 1.0 V-0.18 µm CMOS Tunable Low Pass Filters with 73 dB DR for On-Chip Sensing Acquisition Systems

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 563
Author(s):  
Jorge Pérez-Bailón ◽  
Belén Calvo ◽  
Nicolás Medrano
Keyword(s):  
Power Consumption ◽  
Dynamic Range ◽  
Low Voltage ◽  
Cutoff Frequency ◽  
Cmos Technology ◽  
Active Area ◽  
Current Steering ◽  
Low Pass ◽  
On Chip ◽  
Low Pass Filters

This paper presents a new approach based on the use of a Current Steering (CS) technique for the design of fully integrated Gm–C Low Pass Filters (LPF) with sub-Hz to kHz tunable cut-off frequencies and an enhanced power-area-dynamic range trade-off. The proposed approach has been experimentally validated by two different first-order single-ended LPFs designed in a 0.18 µm CMOS technology powered by a 1.0 V single supply: a folded-OTA based LPF and a mirrored-OTA based LPF. The first one exhibits a constant power consumption of 180 nW at 100 nA bias current with an active area of 0.00135 mm2 and a tunable cutoff frequency that spans over 4 orders of magnitude (~100 mHz–152 Hz @ CL = 50 pF) preserving dynamic figures greater than 78 dB. The second one exhibits a power consumption of 1.75 µW at 500 nA with an active area of 0.0137 mm2 and a tunable cutoff frequency that spans over 5 orders of magnitude (~80 mHz–~1.2 kHz @ CL = 50 pF) preserving a dynamic range greater than 73 dB. Compared with previously reported filters, this proposal is a competitive solution while satisfying the low-voltage low-power on-chip constraints, becoming a preferable choice for general-purpose reconfigurable front-end sensor interfaces.

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