Development of Low-Cost Instrumentation for Single Point Autofluorescence Lifetime Measurements

Abstract. Unmanned Aerial Vehicles (UAV) are established platforms for photogrammetric surveys in remote areas. They are lightweight, easy to operate and can allow access to remote sites otherwise difficult (or impossible) to be surveyed with other techniques. Very good accuracy can be obtained also with low-cost UAV platforms as far as a reliable ground control is provided. However, placing ground control points (GCP) in these contexts is time consuming and requires accessibility that, in some cases, can be troublesome. RTK-capable UAV platforms are now available at reasonable costs and can overcome most of these problems, requiring just few (or none at all) GCP and still obtaining accurate results. The paper will present a set of experiments performed in cooperation with ARPA VdA (the Environmental Protection Agency of Valle d’Aosta region, Italy) on a test site in the Italian Alps using a Dji Phantom 4 RTK platform. Its goals are: a) compare accuracies obtainable with different calibration procedures (pre- or on-the-job/self-calibration); b) evaluate the accuracy improvements using different number of GCP when the site allows for it; and c) compare alternative positioning modes for camera projection centres determination, (Network RTK, RTK, Post Processing Kinematic and Single Point Positioning).

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Software-Defined Edge Cloud Framework for Resilient Multitenant Applications

Wireless Communications and Mobile Computing ◽

10.1155/2019/3947286 ◽

2019 ◽

Vol 2019 ◽

pp. 1-17

Author(s):

Kaikai Liu ◽

Nagthej Manangi Ravindrarao ◽

Abhishek Gurudutt ◽

Tejeshwar Kamaal ◽

Chinmayi Divakara ◽

...

Keyword(s):

Low Cost ◽

Single Point ◽

Cloud Services ◽

Wide Area Networks ◽

Software Framework ◽

Service Migration ◽

Cloud Framework ◽

Data Source ◽

Point Control ◽

Lightweight Container

Edge application’s distributed nature presents significant challenges for developers in orchestrating and managing the multitenant applications. In this paper, we propose a practical edge cloud software framework for deploying multitenant distributed smart applications. Here we exploit commodity, a low cost embedded board to form distributed edge clusters. The cluster of geo-distributed and wireless edge nodes not only power multitenant IoT applications that are closer to the data source and the user, but also enable developers to remotely deploy and orchestrate application containers over the cloud. Specifically, we propose building a software platform to manage the distributed edge nodes along with support services to deploy and launch isolated and multitenant user applications through a lightweight container. In particular, we propose an architectural solution to improve the resilience of edge cloud services through peer collaborated service migration when the failures happen or when resources are overburdened. We focus on giving the developers a single point control of the infrastructure over the intermittent and lossy wide area networks (WANs) and enabling the remote deployment of multitenant applications.

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Low-cost single-point optoacoustic sensor for spectroscopic measurement of local vascular oxygenation

Optics Letters ◽

10.1364/ol.412034 ◽

2020 ◽

Vol 45 (24) ◽

pp. 6579

Author(s):

Antonios Stylogiannis ◽

Lucas Riobo ◽

Ludwig Prade ◽

Sarah Glasl ◽

Sabine Klein ◽

...

Keyword(s):

Low Cost ◽

Single Point ◽

Spectroscopic Measurement

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Thickness Distribution and Forming Strategy Analysis for Two Point Incremental Forming with a Male Die

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.337.452 ◽

2011 ◽

Vol 337 ◽

pp. 452-455 ◽

Cited By ~ 1

Author(s):

Zhao Bing Liu ◽

Paul Meehan ◽

Paul Bellette

Keyword(s):

Incremental Forming ◽

Low Cost ◽

Thickness Distribution ◽

Single Point ◽

Three Dimensional ◽

Dimensional Accuracy ◽

Strategy Analysis ◽

Multi Stage ◽

Analytical Perspective ◽

Forming Strategy

Incremental Sheet Forming (ISF) is a promising sheet-metal-forming technology which is drawing more and more researchers’ attention due to its flexibility of manufacturing three-dimensional products at a relatively low cost for rapid prototyping and small-batch production. This paper is focused on the thickness distribution and the forming strategy analysis for two point incremental forming with a male die. The analyzed benchmark is half a torus which is generated by revolving a semi-circle. Such a part is hardly able to be formed by single point incremental forming because its slope varies from 0 degree to 90 degrees. In terms of the varying slope, the variant of sine’s law is derived to give an approximate prediction of the thickness distribution from an analytical perspective. In addition, a multi-stage forming strategy is proposed in order to form the part successfully. In particular, a keying operation is implemented carefully in order to avoid twist phenomenon and achieve good dimensional accuracy.

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A LOW-COST PULSED TUNABLE UV LASER FOR FLUORESCENCE LIFETIME MEASUREMENTS

Photochemistry and Photobiology ◽

10.1111/j.1751-1097.1974.tb06552.x ◽

1974 ◽

Vol 20 (1) ◽

pp. 85-88 ◽

Cited By ~ 12

Author(s):

Leonard J. Andrews ◽

Cornelius Mahoney ◽

Leslie S. Forster

Keyword(s):

Fluorescence Lifetime ◽

Low Cost ◽

Uv Laser ◽

Lifetime Measurements

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Study On The Single Point Incremental Sheet Forming of AISI 321 Variable Wall Angle Geometry

10.21203/rs.3.rs-836822/v1 ◽

2021 ◽

Author(s):

Muhammad Jawad Afzal ◽

Asif Israr ◽

Muhammad Soban Akram ◽

Abdul Muqeet

Keyword(s):

Low Cost ◽

Single Point ◽

Cnc Machine ◽

Forming Process ◽

Wall Angle ◽

Metal Forming Process ◽

Clamping System ◽

Variable Wall ◽

Aisi 321 ◽

Wall Geometry

Abstract For rapid prototyping, design validation and small batch productions process with low tooling cost is preferred. Single Point Incremental Forming (SPIF) is a die-less sheet metal forming process which requires only low cost forming tool driven by CNC machine in a toolpath to form required geometry at room temperature from sheet blank clamped in a low cost and low stiffness clamping system. In this study, effect of process parameters such as tool radius, feed rate and lubrication are considered on the formability of the truncated profile of AISI 321 Variable Wall Geometry (VWA). Set parameters conditions with 2 level layers are optimized using numerical and statistical approach. Experimentation on the same setup is carried out by selecting the most, least and mid favorable solutions optimized on the basis of forming forces and stresses in the sheet. Geometrical accuracy, sheet thinning, and forming forces are compared analytically, numerically and experimentally addressing the inadequacy of analytically models for Variable Wall Angle Geometries.

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DEVELOPMENT AND EVALUATION OF A UAV BASED MAPPING SYSTEM FOR REMOTE SENSING AND SURVEYING APPLICATIONS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xl-1-w4-233-2015 ◽

2015 ◽

Vol XL-1/W4 ◽

pp. 233-239 ◽

Cited By ~ 20

Author(s):

C. Eling ◽

M. Wieland ◽

C. Hess ◽

L. Klingbeil ◽

H. Kuhlmann

Keyword(s):

Remote Sensing ◽

Reference Point ◽

Time Synchronization ◽

Low Cost ◽

Single Point ◽

Single Frequency ◽

Dual Frequency ◽

Lever Arm ◽

Rtk Gps ◽

Camera Synchronization

In recent years, unmanned aerial vehicles (UAVs) have increasingly been used in various application areas, such as in the remote sensing or surveying. For these applications the UAV has to be equipped with a mapping sensor, which is mostly a camera. Furthermore, a georeferencing of the UAV platform and/or the acquired mapping data is required. The most efficient way to realize this georeferencing is the direct georeferencing, which is based on an onboard multi-sensor system. In recent decades, direct georeferencing systems have been researched and used extensively in airborne, ship and land vehicle applications. However, these systems cannot easily be adapted to UAV platforms, which is mainly due to weight and size limitations. In this paper a direct georeferencing system for micro- and mini-sized UAVs is presented, which consists of a dual-frequency geodetic grade OEM GPS board, a low-cost single-frequency GPS chip, a tactical grade IMU and a magnetometer. To allow for cm-level position and sub-degree attitude accuracies, RTK GPS (real-time kinematic) and GPS attitude (GPS compass) determination algorithms are running on this system, as well as a GPS/IMU integration. Beside the direct georeferencing, also the precise time synchronization of the camera, which acts as the main sensor for mobile mapping applications, and the calibration of the lever arm between the camera reference point and the direct georeferencing reference point are explained in this paper. Especially the high accurate time synchronization of the camera is very important, to still allow for high surveying accuracies, when the images are taken during the motion of the UAV. Results of flight tests demonstrate that the developed system, the camera synchronization and the lever arm calibration make directly georeferenced UAV based single point measurements possible, which have cm-level accuracies on the ground.

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Codephase center corrections for multi GNSS signals and the impact of misoriented antennas

10.5194/egusphere-egu2020-9846 ◽

2020 ◽

Author(s):

Yannick Breva ◽

Johannes Kröger ◽

Tobias Kersten ◽

Steffen Schön

Keyword(s):

Low Cost ◽

Single Point ◽

Antenna Pattern ◽

Post Processing ◽

Phase Measurements ◽

Antenna Phase ◽

Point Positioning ◽

Antenna Phase Center ◽

Single Differences ◽

The Impact

In absolute positioning approaches, e.g. Precise Point Positioning (PPP), antenna phase center corrections (PCC) have to be taking into account. Beside PCC for carrier phase measurements, also codephase center corrections (CPC) exist, which are antenna dependent delays of the code. The CPC can be split into a codephase center offset (PCO) and codephase center variations (CPV). These corrections can be applied in a Single Point Positioning (SPP) approach, to improve the accuracy in the positioning domain. The CPC vary with azimuth and elevation and are related to an antenna, which is oriented towards north. If the antenna is wrongly oriented, the effect cannot be compensated and wrong corrections will be added to the observations.The Institut f&#252;r Erdmessung (IfE) established a concept to determine CPC for multi GNSS signals, where a robot tilts and rotates an antenna under test precisely around a specific point. Afterwards time differenced single differences are calculated, which are the input to estimate the CPC by using spherical harmonics (8,8). First studies in our working group showed, that an improvement of the position in a SPP are possible, if antenna pattern for the codephase are considering and correctly applied.In this contribution, we present the improvement of a SPP and PPP approach by considering CPC for different low cost antennas with multi GNSS signals. Beside the positioning domain, an analysis of the CPC in observation domain, by evaluating the deviations of single differences from zero mean, is performed. Furthermore, we quantify the impact of a disoriented antenna, e.g. oriented in east direction, in the positioning and observation domain by using north oriented CPC. We show, that this impact can be compensating in a post-processing by rotating the antenna pattern. Finally, we present some results of different calibrations, where the antennas are disoriented on the robot and compared to the estimated CPC pattern with the post-processing approach and discussed their impact on the positioning.&#160;

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A Robust GNSS/PDR Integration Scheme with GRU-Based Zero-Velocity Detection for Mass-Pedestrians

Remote Sensing ◽

10.3390/rs14020300 ◽

2022 ◽

Vol 14 (2) ◽

pp. 300

Author(s):

Dongpeng Xie ◽

Jinguang Jiang ◽

Jiaji Wu ◽

Peihui Yan ◽

Yanan Tang ◽

...

Keyword(s):

Low Cost ◽

Single Point ◽

Dead Reckoning ◽

Satellite System ◽

Integration Scheme ◽

Fusion Algorithm ◽

Zero Velocity ◽

Single Antenna ◽

Other Information ◽

Global Navigation Satellite

Aiming at the problem of high-precision positioning of mass-pedestrians with low-cost sensors, a robust single-antenna Global Navigation Satellite System (GNSS)/Pedestrian Dead Reckoning (PDR) integration scheme is proposed with Gate Recurrent Unit (GRU)-based zero-velocity detector. Based on the foot-mounted pedestrian navigation system, the error state extended Kalman filter (EKF) framework is used to fuse GNSS position, zero-velocity state, barometer elevation, and other information. The main algorithms include improved carrier phase smoothing pseudo-range GNSS single-point positioning, GRU-based zero-velocity detection, and adaptive fusion algorithm of GNSS and PDR. Finally, the scheme was tested. The root mean square error (RMSE) of the horizontal error in the open and complex environments is lower than 1 m and 1.5 m respectively. In the indoor elevation experiment where the elevation difference of upstairs and downstairs exceeds 25 m, the elevation error is lower than 1 m. This result can provide technical reference for the accurate and continuous acquisition of public pedestrian location information.

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Drone Surveying of Volumetric Ice Growth in a Steep River

Frontiers in Remote Sensing ◽

10.3389/frsen.2021.767073 ◽

2021 ◽

Vol 2 ◽

Author(s):

Einar Rødtang ◽

Knut Alfredsen ◽

Ana Juárez

Keyword(s):

Structure From Motion ◽

Complex Geometry ◽

Low Cost ◽

Single Point ◽

Ice Cover ◽

River Ice ◽

Ice Thickness ◽

Surface Geometry ◽

Ice Volume ◽

Anchor Ice

Representative ice thickness data is essential for accurate hydraulic modelling, assessing the potential for ice induced floods, understanding environmental conditions during winter and estimation of ice-run forces. Steep rivers exhibit complex freeze-up behaviour combining formation of columnar ice with successions of anchor ice dams to build a complete ice cover, resulting in an ice cover with complex geometry. For such ice covers traditional single point measurements are unrepresentative. Gathering sufficiently distributed measurements for representativeness is labour intensive and at times impossible with hard to access ice. Structure from Motion (SfM) software and low-cost drones have enabled river ice mapping without the need to directly access the ice, thereby reducing both the workload and the potential danger in accessing the ice. In this paper we show how drone-based photography can be used to efficiently survey river ice and how these photographic surveys can be processed into digital elevation models (DEMs) using Structure from Motion. We also show how DEMs of the riverbed, riverbanks and ice conditions can be used to deduce ice volume and ice thickness distributions. A QGIS plugin has been implemented to automate these tasks. These techniques are demonstrated with a survey of a stretch of the river Sokna in Trøndelag, Norway. The survey was carried out during the winter 2020–2021 at various stages of freeze-up using a simple quadcopter with camera. The 500 m stretch of river studied was estimated to have an ice volume of up to 8.6 × 103 m3 (This corresponds to an average ice thickness of ∼67 cm) during the full ice cover condition of which up to 7.2 × 103 m3 (This corresponds to an average ice thickness of ∼57 cm) could be anchor ice. Ground Control Points were measured with an RTK-GPS and used to determine that the accuracy of these ice surface geometry measurements lie between 0.03 and 0.09 m. The ice thicknesses estimated through the SfM methods are on average 18 cm thicker than the manual measurements. Primarily due to the SfM methods inability to detect suspended ice covers. This paper highlights the need to develop better ways of estimating the volume of air beneath suspended ice covers.

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