A smart rig for calibration of gas sensor nodes

Electrochemical gas sensors require regular maintenance to check and secure proper functioning. Standard procedures usually involve testing and recalibration of the sensors, for which working environments are needed. Periodic calibration is therefore necessary to ensure reliable and accurate measurements. This paper proposes a dedicated smart calibration rig with a set of novel features enabling simultaneous calibration of multiple sensors. The proposed calibration rig system comprises a gas mixing system, temperature control system, a test chamber, and a process-control PC that controls all calibration phases. The calibration process is automated by a LabVIEW-based platform that controls the calibration environment for the sensor nodes, logs sensor data, and best fit equation based on interpolation for every sensor on the node and uploads it to the sensor node for next deployments. The communication between the PC and the sensor nodes is performed using the same IEEE 802.15.4 (ZigBee) protocol that the nodes also use in field deployment for air quality measurement. The results presented demonstrate the effectiveness of the sensors calibration rig.Scopu

Study of the effects of dust, relative humidity, and temperature on solar PV performance in Doha: Comparison between monocrystalline and amorphous PVS

The sensitivity of various solar photovoltaic technologies to dust, temperature, and relative humidity is investigated for Doha's environment. Results obtained show that monocrystalline photovoltaics (PVs) have efficiencies as high as 85% compared to 70% for amorphous ones. Also, dust accumulation degrades more critically the efficiency of amorphous and monocrystalline silicon PVs than the panel's temperature or relative humidity. In addition, the results show that amorphous PVs are more affected by temperature and relative humidity than monocrystalline PVs. However, amorphous PVs prove to be more robust against dust settlement than monocrystalline PVs and hence are more suitable for implementation in desert climates like Doha unless cleaning strategies are devised. It was estimated that 100 days of dust accumulation over monocrystalline PV panels, caused the efficiency to decrease by around 10%. This limitation makes solar PVs to represent an unreliable source of power for unattended or remote devices and thus strongly suggests the challenge of cleaning the panel's surface regularly or injecting technical modifications. Furthermore, the study suggests operating solar PV plants in Doha from 11:00 am to 02:00 pm to optimize production.Scopu

A New Low Cost Linear Resolver Converter

A new low cost converter topology is proposed for sinusoidal position encoders. The converter enables determination of the angle from the sine and cosine signals of the encoder. When used with resolvers, the implementation of the present scheme takes advantage of the available excitation signal used to operate the device. This trigonometric reference signal is optimally used to generate an analogue signal equivalent to a digital look-up table (LUT). This enables determination of the mechanical angle without using LUT, A/D, and D/A converters. The scheme is optimized in order to achieve highest possible precision. Beside simplicity of its implementation, the proposed converter offers the advantage of robustness to amplitude fluctuation of the transducer excitation signal. The converter was implemented using ordinary low-cost analog components. The theory of operation, computer simulation, and experimental results are given

A resolver converter based upon a novel open-Loop Technique

The paper presents a novel technique for the determination of the angle from slowly-varying quadrature co-sinusoidal signals produced, for example, by position sensors. In the presented scheme applied to a resolver, the separately generated constant-frequency sine wave used for exciting the resolver together with an additional cosine wave are used as reference against which the amplitudes of the angle-dependent demodulated resolver sine and cosine signals are compared. At the instant equality between respective amplitudes of the signals are detected, two sample and hold circuits sample a voltage proportional to the angle of the shaft of the resolver from a triangular waveform generated from the reference signals. In theory, the sample and hold devices produce identical output voltages proportional to the unknown angle of the transducer. In order to improve the precision of the proposed converter, the two sample and hold circuits outputs are fed into a multiplexer to produce a single output that takes full advantage of the accurate comparison outside the peak regions of the signals. With this method, the validated output is obtained from the accurate comparisons involving the alternating pseudo-linear segments of the trigonometric signals. Another important feature of this converter is its robustness to amplitude fluctuations in the trigonometric reference signals which are used for the excitation of the resolver. A converter based on this technique has been successfully implemented using basic electronic components. Theory of operation, computer simulation and experimental results are given

An open-loop technique for angle determination from position encoders

The paper presents a novel technique for the determination of the angle from low-frequency quadrature cosinusoidal signals produced, for example, by position sensors. In the presented scheme applied to a resolver, the separately generated constant-frequency sine wave used for exciting the resolver together with an additional cosine wave are used as reference against which the amplitudes of the angle-dependent demodulated resolver sine and cosine signals are compared. At the instant equality between amplitudes of respective signals are detected, a sample and hold circuit samples a voltage proportional to the angle of the shaft of the resolver from a triangular waveform generated from the reference signals. This is a feed-forward method, which is an analog equivalent to digital look up table techniques. In order to improve the precision of the proposed converter, a new technique is used to take full advantage of the alternating pseudo-linear segments of the trigonometric signals. With this method, the sampling relies only on the accurate comparison outside the peak regions of the signals. A converter based on this technique has been successfully implemented using basic electronic components. Theory of operation, computer simulation and experimental results are given

Real-time gradient-aware indigenous AQI estimation IoT platform

Environmental monitoring has gained significant importance in outdoor air quality measurement and assessment for fundamental survival as well as ambient assisted living. In real-time outdoor urban scale, instantaneous air quality index estimation, the electrochemical sensors warm-up time, cross-sensitivity computation-error, geo-location typography, instantaneous capacity or back up time; and energy efficiency are the six major challenges. These challenges lead to real-time gradient anomalies that effect the accuracy and pro-longed lags in air quality index mapping campaigns for state and environmental/meteorological agencies. In this work, a gradient-aware, multi-variable air quality sensing node is proposed with event-triggered sensing based on position, gas magnitudes, and cross-sensitivity interpolation. In this approach, temperature, humidity, pressure, geo-position, photovoltaic power, volatile organic compounds, particulate matter (2.5), ozone, Carbon mono-oxide, Nitrogen dioxide, and Sulphur dioxide are the principle variables. Results have shown that the proposed system optimized the real-time air quality monitoring for the chosen geo-spatial cluster (Qatar University).Scopu

A real-time gradient aware multi-variable handheld urban scale air quality mapping IoT system

In outdoor urban scale air quality mapping, electrochemical sensors warm-up time, cross-sensitivity, geo-location typography, and energy efficiency are major challenges. These challenges lead to real-time gradient anomalies that effect the accuracy and prolonged lags in air quality mapping campaigns for state and environmental/meteorological agencies. In this work, a gradient aware, multi-variable air quality sensing node is proposed with event-triggered sensing based on position, gas magnitudes, and cross-sensitivity interpolation. In this approach, temperature, humidity, pressure, geo-position, photovoltaic power, volatile organic compounds, particulate matter, ozone, Carbon mono-oxide, Nitrogen dioxide, and Sulphur dioxide are the principle variables. Results have shown that the proposed system optimized the real-time air quality mapping for the chosen geo-spatial cluster, i.e. Qatar University.Scopu

An Autonomous Multi-Variable Outdoor Air Quality Mapping Wireless Sensors IoT Node for Qatar

In all outdoor long haul air quality monitoring and mapping applications, sensing accuracy, the sustainability of telemetry, and resilience in node systems and operation are major challenges. The severity of these challenges varies depending on the moderateness and harshness of the climate of observation. In this work, an autonomous environmentally powered, sensors self-diagnostic/calibration, and context-aware IoT-based telemetry for multi-variable sensing node is being proposed. In this node, photo-voltaic and piezoelectric energy harvesters contributed to self-calibration and sustainable measurement of temperature (in °C), humidity (in %), pressure (in bar), geo-position (in NMEA format), volatile organic compounds-VOC (in ppm), particulate matter PM (in ppm), ozone (in Dobson Unit), Carbon mono-oxide (in ppm), Nitrogen dioxide (in ppm), and Sulphur dioxide (in ppm). Results have shown that the proposed system worked autonomously for days and optimized the real-time air quality mapping for the chosen geo-spatial cluster, i.e. Qatar University.Scopu

Investigation of solar PV performance under Doha weather using a customized measurement and monitoring system

A key factor in future eco-friendly and reliable energy systems for network stability is energy prediction of renewable resources. However, the climate-induced performance degradation represents a major drawback to solar making them unreliable for unattended or remote plants. We propose a customized cost-effective solution that allows monitoring and predicting the performance of PV systems, fostering thus efficient planning and control strategies for network stability. More specifically, we design an in-house system featuring a buck-boost converter enhanced with a maximum power point tracker (MPPT) serving as a PV load, sensors' system that collects climatic parameters including dust, wireless Radio, and a LabVIEW based monitoring and recording station. We have presented thoroughly all the system design steps. The system was deployed in Doha over a long period of time under harsh environment. It allows accessing and processing of recorded data ubiquitously over the web or from a database. Based on the recorded data, the power output for a given PV technology under any environment can be analyzed. Results predict that the maximum power output from a Poly-crystalline panel decreases by around 30% for a dust exposure of five months. This would suggest cleaning needs and advise on cleaning frequencies of PV panels.The authors would like to thank Qatar University for funding this research ( QUUG-CENG-DEE-12/13-2 ) and providing the necessary tools and equipment. Also, we would like to thank Dr. Ahmed Mohammed Massoud (EE Dept. of Qatar University) for his support.Scopu

Platoon Transitional Maneuver Control System: A Review

Connectivity and autonomy are considered two of the most promising technologies to improve mobility, fuel consumption, travel time, and traffic safety in the automated transportation industry. These benefits can be realized through vehicle platooning. A vehicle platoon is composed of a group of connected automated vehicles (CAVs) traveling together at consensual speed, following the leading vehicle (leader) while maintaining a prespecified inter-vehicle distance. This paper reviews the different existing control techniques associated with the transitional platoon maneuvers such as merge/split and lane change. Different longitudinal and lateral vehicle dynamics that are mainly used in the transitional platoon maneuvers are discussed. The most used control algorithms for both longitudinal and lateral control used for transitional platoon maneuvers are reviewed and the advantages and limitations of each control strategy are discussed. The most recent articles on platoon control maneuvers have been analyzed based on the proposed control algorithm, homogeneously or heterogeneously of platoon members, type of platoon maneuver, the aim of control problem, type of implementation, and used simulation tools. This paper also discusses different trajectory planning techniques used in lateral motion control and studies the most recent research related to trajectory planning for automated vehicles and summarizes them based on the used trajectory planning technique, platoon or/and lane change, the type of traffic, and the cost functions. Finally, this paper explores the open issues and directions for future research.Scopu