scholarly journals Clustering approaches to improve the performance of low cost air pollution sensors

2017 ◽  
Vol 200 ◽  
pp. 621-637 ◽  
Author(s):  
Katie R. Smith ◽  
Peter M. Edwards ◽  
Mathew J. Evans ◽  
James D. Lee ◽  
Marvin D. Shaw ◽  
...  
Keyword(s):  
Air Pollution ◽  
Supply Voltage ◽  
Low Cost ◽  
Linear Interpolation ◽  
External Reference ◽  
Single Chemical ◽  
Cost Competitiveness ◽  
Sensor Signals ◽  
Co Sensor ◽  
The Cost

Low cost air pollution sensors have substantial potential for atmospheric research and for the applied control of pollution in the urban environment, including more localized warnings to the public. The current generation of single-chemical gas sensors experience degrees of interference from other co-pollutants and have sensitivity to environmental factors such as temperature, wind speed and supply voltage. There are uncertainties introduced also because of sensor-to-sensor response variability, although this is less well reported. The sensitivity of Metal Oxide Sensors (MOS) to volatile organic compounds (VOCs) changed with relative humidity (RH) by up to a factor of five over the range of 19–90% RH and with an uncertainty in the correction of a factor of two at any given RH. The short-term (second to minute) stabilities of MOS and electrochemical CO sensor responses were reasonable. During more extended use, inter-sensor quantitative comparability was degraded due to unpredictable variability in individual sensor responses (to either measurand or interference or both) drifting over timescales of several hours to days. For timescales longer than a week identical sensors showed slow, often downwards, drifts in their responses which diverged across six CO sensors by up to 30% after two weeks. The measurement derived from the median sensor within clusters of 6, 8 and up to 21 sensors was evaluated against individual sensor performance and external reference values. The clustered approach maintained the cost competitiveness of a sensor device, but the median concentration from the ensemble of sensor signals largely eliminated the randomised hour-to-day response drift seen in individual sensors and excluded the effects of small numbers of poorly performing sensors that drifted significantly over longer time periods. The results demonstrate that for individual sensors to be optimally comparable to one another, and to reference instruments, they would likely require frequent calibration. The use of a cluster median value eliminates unpredictable medium term response changes, and other longer term outlier behaviours, extending the likely period needed between calibration and making a linear interpolation between calibrations more appropriate. Through the use of sensor clusters rather than individual sensors, existing low cost technologies could deliver significantly improved quality of observations.

scholarly journals Solar Rankine Engines: Examples and Projected Costs

1979 ◽  
Author(s):  
R. E. Barber
Keyword(s):  
Power Systems ◽  
Solar Power ◽  
Low Cost ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Solar Heat ◽  
Shaft Power ◽  
Cost Competitiveness ◽  
The Cost ◽  
Made In

Solar heat can be converted into shaft power by use of the Organic Rankine Cycle Engine (ORCE). The efficiency of the ORCE to convert the solar heat to shaft power varies from 7 or 8 percent for an ORCE heated by low temperature flat plate collectors at 200 F, to near 15 percent when heated by intermediate temperature collectors (300 F), and up to 25 percent with high temperature concentrating collectors (600 F). Barber-Nichols designed, built, and tested its first solar heated ORCE in 1973, which produced three tons of air conditioning. Since that time, the three-ton unit has reached its fourth iteration on the development path to production; a 77-ton water chiller was installed at LASL; two ORCE drives for 100-ton water chillers were delivered to Honeywell; seven 25-ton water Chillers were delivered to DOE demonstration sites; and a 25-hp ORCE for irrigation pumping was installed in Willard, N.M. Photographs, design details, and the measured performance of these units are presented herein as examples. The cost of solar power systems using an ORCE is also presented which shows that for the current $150 to $200/m2 cost of cencentrating collectors, the system cost would be in excess of $2500/kw peak. The ORCE is approximately 25 percent of this cost or $600/kw. Consequently, while reductions in the cost and improvements in the performance of the ORCE can and should be made in the development process, the cost competitiveness of a solar power system is largely dependent on developing low cost concentrating collectors which can be sold for 1/2 to 1/3 of today’s price.

scholarly journals Mobility-on-demand pricing versus private vehicle TCO: how cost structures hinder the dethroning of the car

2021 ◽  
Author(s):  
Tobias Kuhnimhof ◽  
Christine Eisenmann
Keyword(s):  
Low Cost ◽  
Lower Boundary ◽  
Skewed Distribution ◽  
On Demand ◽  
Cost Structures ◽  
Private Households ◽  
Cost Competitiveness ◽  
Private Car ◽  
The Cost ◽  
Car Travel

AbstractThis study uses a unique dataset on the cost of motoring in Germany to analyse cost competitiveness of emerging mobility-on-demand (MOD) services. Previous studies have focused on comparing current and projected MOD prices with the average cost of private motoring. This study quantifies which proportion of private car travel would actually turn out to be costlier than MOD given that MOD costs drop below certain levels relative to the cost of private motoring. In this context, not the average but the distribution of the costs of motoring are the key issue. These costs are strongly skewed across the cars in private households when including new and old vehicles: a large proportion of private car kilometres are driven at relatively low cost. The study uses simplified scenario settings with MOD price levels ranging from 0.1 €/km to 1.5 €/km to make predictions of hypothetical modal shifts under the assumption that car user switch to the most economic mode of travel. These modal shifts serve as an indicator of MOD cost competitiveness. The results indicate that MOD prices would have to drop to 0.5 €/km or lower to have a notable impact on use of the private car if cost was the key mode choice criterion. Only if MOD prices drop down to a level of about 0.3 €/km—quite possibly a lower boundary for automated MOD—MOD-enabled mobility packages would be the less costly alternative to the private car for a substantial proportion of mileage. However, even at that MOD price level, the private car would still be the most economic option for the majority of today’s car user kilometres. Our findings illustrate that the skewed distribution of the cost of owning and running private cars—where many of those who drive much drive inexpensively—substantially dampens the disruptive potential of MOD. While we use data from Germany to illustrate this, many of our findings are more widely applicable.

Theoretical Design Strategies, Strengths, Costs, and Environmental Impacts of Triple Composite Beams Utilizing Glass Compressive Reinforcement

2020 ◽  
Vol 4 (1) ◽  
pp. 22 ◽  
Author(s):  
John Cotter ◽  
Rasim Guldiken
Keyword(s):  
Low Cost ◽  
Beam Theory ◽  
Composite Beams ◽  
Alternative Form ◽  
Design Strategies ◽  
Beam Design ◽  
R Ratio ◽  
Macro Scale ◽  
Cost Competitiveness ◽  
The Cost

Due to increasing costs and growing environmental concerns pertaining to the construction of structures, an alternative form of reinforcement has been proposed through our studies; through a new beam design methodology, referred to as triple composite beams, glass can be used as a cost-competitive and more environmentally friendly macro-scale compressive reinforcement. The cost competitiveness of glasses derives from their large compressive strength (in general 1000 MPa; >1100 MPa for fused quartz). To support the triple composite design architecture, equations have been developed using Euler–Bernoulli beam theory and the method of transformed sections and compared against finite element modeling determined stresses. Our results show that the average stress was more accurate but less precise than fully considering binder, assuming the binder did not contribute to the cross-section of the beam. The paper concludes by presenting a flexural reinforcement utilization ratio (R), which predicts the ability of a reinforcement-binder combination to utilize the reinforcement to maximum stress effectively while ignoring bonding strength. This R ratio suggests that while concrete is a low cost, it cannot be used in a glass-reinforced beam as the concrete is too stiff compared to the glass.

scholarly journals Field Calibration of Low-Cost Air Pollution Sensors

2019 ◽  
Author(s):  
Andres Gonzalez ◽  
Adam Boies ◽  
Jacob Swason ◽  
David Kittelson
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Relative Humidity ◽  
Low Cost ◽  
Quality Data ◽  
Ambient Conditions ◽  
Field Calibration ◽  
Broadcasting System ◽  
The Cost ◽  
Environmental Agencies

Abstract. To implement effective policies and strategies to control air pollution, it is crucial to obtain accurate air quality data. Stationary air monitoring stations (AMSs) help local authorities and environmental agencies in achieving these goals; however, these measurements have limitations. AMSs provide detailed temporal data on air quality, but only at discrete locations at relatively high cost. An alternative method, low-cost mobile air quality monitoring (LCMAQM) sensors, complement AMSs. LCMAQM sensors can cover larger areas and the cost of typical sensors for LCMAQM are $150–200 each. We have developed a wireless Mobile Autonomous Air Quality Sensor box (MAAQSbox) to measure air pollution. The MAAQSbox contains LCMAQM sensors (gas and particle) and a wireless broadcasting system, which enables autonomous field operation for varied mobile applications. Nitrogen dioxide (NO2), nitric oxide (NO), carbon monoxide (CO), and ozone (O3) gases are measured by B4 sensors. Particulate matter (PM2.5) is measured by OPC-N2. A field calibration has been performed by making side by side measurements with the MAAQSbox and Minnesota Pollution Agency AMS. The calibrations of LCMAQM sensors were determined by multivariate linear regressions (MLR). MLR results for all sensors were improved by including the temperature and relative humidity as independent variables. The R2 of CO, NO, NO2, and O3 gas sensors are 0.96, 0.97, 0.81, and 0.95 respectively, while the R2 of PM2.5 particle sensor is 0.6. B4 sensors are sensitive to ambient conditions such as temperature and relative humidity. The results with OPC-N2 differs from the AMS indicating further developments are needed to enable more accurate PM2.5 measurements.

The Cost of Air Pollution in Lagos

10.1596/33038 ◽  
2019 ◽  
Author(s):  
Lelia Croitoru ◽  
Jiyoun Christina Chang ◽  
Andrew Kelly
Keyword(s):  
Air Pollution ◽  
The Cost

Advance Protection for Three Phase Induction Motor using Microcontroller Atmega32

2018 ◽  
Vol 8 (1) ◽  
pp. 172
Author(s):  
Karan S Belsare ◽  
Gajanan D Patil
Keyword(s):  
Induction Motor ◽  
Low Cost ◽  
Short Circuit ◽  
Cost Factor ◽  
Protection Scheme ◽  
Three Phase ◽  
The Cost

A low cost and reliable protection scheme has been designed for a three phase induction motor against unbalance voltages, under voltage, over voltage, short circuit and overheating protection. Taking the cost factor into consideration the design has been proposed using microcontroller Atmega32, MOSFETs, relays, small CTs and PTs. However the sensitivity of the protection scheme has been not compromised. The design has been tested online in the laboratory for small motors and the same can be implemented for larger motors by replacing the i-v converters and relays of suitable ratings.

Janus – A New Approach to Air Combat Pilot Training

2019 ◽  
Vol 2019 (4) ◽  
pp. 7-22
Author(s):  
Georges Bridel ◽  
Zdobyslaw Goraj ◽  
Lukasz Kiszkowiak ◽  
Jean-Georges Brévot ◽  
Jean-Pierre Devaux ◽  
...  
Keyword(s):  
Low Cost ◽  
Cost Effective ◽  
High Energy ◽  
Training System ◽  
Embedded Sensors ◽  
Pilot Training ◽  
New Approach ◽  
Combat Aircraft ◽  
Air Combat ◽  
The Cost

Abstract Advanced jet training still relies on old concepts and solutions that are no longer efficient when considering the current and forthcoming changes in air combat. The cost of those old solutions to develop and maintain combat pilot skills are important, adding even more constraints to the training limitations. The requirement of having a trainer aircraft able to perform also light combat aircraft operational mission is adding unnecessary complexity and cost without any real operational advantages to air combat mission training. Thanks to emerging technologies, the JANUS project will study the feasibility of a brand-new concept of agile manoeuvrable training aircraft and an integrated training system, able to provide a live, virtual and constructive environment. The JANUS concept is based on a lightweight, low-cost, high energy aircraft associated to a ground based Integrated Training System providing simulated and emulated signals, simulated and real opponents, combined with real-time feedback on pilot’s physiological characteristics: traditionally embedded sensors are replaced with emulated signals, simulated opponents are proposed to the pilot, enabling out of sight engagement. JANUS is also providing new cost effective and more realistic solutions for “Red air aircraft” missions, organised in so-called “Aggressor Squadrons”.

scholarly journals H2020 project CAPTOR dataset: raw data collected by low-cost MOX ozone sensors in a real air pollution monitoring network.

Data in Brief ◽  
2021 ◽  
pp. 107127
Author(s):  
Jose M. Barcelo-Ordinas ◽  
Pau Ferrer-Cid ◽  
Jorge Garcia-Vidal ◽  
Mar Viana ◽  
Ana Ripoll
Keyword(s):  
Air Pollution ◽  
Low Cost ◽  
Monitoring Network ◽  
Pollution Monitoring ◽  
Raw Data ◽  
Air Pollution Monitoring

scholarly journals A low-cost wireless endoscope camera: a preliminary report

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
J. M. Lazarus ◽  
M. Ncube
Keyword(s):  
Minimally Invasive Surgery ◽  
Minimally Invasive ◽  
Video Transmission ◽  
Low Cost ◽  
Battery Life ◽  
Resource Constrained ◽  
High Definition ◽  
Industry Standard ◽  
Constrained Environments ◽  
The Cost

Abstract Background Technology currently used for surgical endoscopy was developed and is manufactured in high-income economies. The cost of this equipment makes technology transfer to resource constrained environments difficult. We aimed to design an affordable wireless endoscope to aid visualisation during rigid endoscopy and minimally invasive surgery (MIS). The initial prototype aimed to replicate a 4-mm lens used in rigid cystoscopy. Methods Focus was placed on using open-source resources to develop the wireless endoscope to significantly lower the cost and make the device accessible for resource-constrained settings. An off the shelf miniature single-board computer module was used because of its low cost (US$10) and its ability to handle high-definition (720p) video. Open-source Linux software made monitor mode (“hotspot”) wireless video transmission possible. A 1280 × 720 pixel high-definition tube camera was used to generate the video signal. Video is transmitted to a standard laptop computer for display. Bench testing included latency of wireless digital video transmission. Comparison to industry standard wired cameras was made including weight and cost. The battery life was also assessed. Results In comparison with industry standard cystoscope lens, wired camera, video processing unit and light source, the prototype costs substantially less. (US$ 230 vs 28 000). The prototype is light weight (184 g), has no cables tethering and has acceptable battery life (of over 2 h, using a 1200 mAh battery). The camera transmits video wirelessly in near real time with only imperceptible latency of < 200 ms. Image quality is high definition at 30 frames per second. Colour rendering is good, and white balancing is possible. Limitations include the lack of a zoom. Conclusion The novel wireless endoscope camera described here offers equivalent high-definition video at a markedly reduced cost to contemporary industry wired units and could contribute to making minimally invasive surgery possible in resource-constrained environments.

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