Vehicle Rooftop Research Articles

Prediction of Short-Term Ultrafine Particle Exposures Using Real-Time Street-Level Images Paired with Air Quality Measurements.

Within-city ultrafine particle (UFP) concentrations vary sharply since they are influenced by various factors. We developed prediction models for short-term UFP exposures using street-level images collected by a camera installed on a vehicle rooftop, paired with air quality measurements conducted during a large-scale mobile monitoring campaign in Toronto, Canada. Convolutional neural network models were trained to extract traffic and built environment features from images. These features, along with regional air quality and meteorology data were used to predict short-term UFP concentration as a continuous and categorical variable. A gradient boost model for UFP as a continuous variable achieved R2 = 0.66 and RMSE = 9391.8#/cm3 (mean values for 10-fold cross-validation). The model predicting categorical UFP achieved accuracies for "Low" and "High" UFP of 77 and 70%, respectively. The presence of trucks and other traffic parameters were associated with higher UFPs, and the spatial distribution of elevated short-term UFP followed the distribution of single-unit trucks. This study demonstrates that pictures captured on urban streets, associated with regional air quality and meteorology, can adequately predict short-term UFP exposure. Capturing the spatial distribution of high-frequency short-term UFP spikes in urban areas provides crucial information for the management of near-road air pollution hot spots.

Selection of a phase change material for energy storage by multi-criteria decision method regarding the thermal comfort in a vehicle

The use of vehicles is a daily matter worldwide, however, they remain parked most of the time and commonly under the heating sun, leading to a rise in the internal temperature that provokes heating discomfort, and when the temperature drops this discomfort to the user is felt as cold. In this way, to reduce the distress drivers use air-conditioners in the first case and heaters in the second event as needed, making the consumption of energy a common activity. This research method takes a list of phase change materials used in some applications and makes a novel selection of the best material to be implemented on a vehicle's rooftop, which is done by Multicriteria Decision Methods means. The weighting is done by the Entropy weighting method compared with the new method based on the removal effect of criteria (MEREC), the decision-making methods VIKOR, COPRAS and TOPSIS choose the best material and the Spearman's correlation verify its agreement. The best material selected unanimously is the savENRG PCM-HS22P, which latter was simulated by finite elements methods, resulting in the reduction of 9 °C in the internal air when heating and conservation of 4 °C in the cooling with an increasing Phase Change Material layer.

Solar assisted thermoelectric cooling/heating system for vehicle cabin during parking: A numerical study

Vehicles parked under blazing sun increases the cabin temperature to a broiling point as greenhouse effect comes into play. Similar is found in winter season when vehicle is parked in open, cabin temperature falls drastically. This extreme rise and fall in the vehicle cabin temperature, results in more fossil fuel consumption to power air-conditioner for high loads, which eventually leads to increase in generation of harmful gases. Additionally, the drastic condition inside vehicle cabin makes it profusely miserable for human comfort. Thus, relevant renewable energy powered cooling/heating system is required for the vehicle cabin when parked in open areas. Therefore, in this study initially, a 3D heat and mass transfer model is developed for evaluating temperature variations in vehicle cabin for summer and winter seasons. Then, a solar powered thermoelectric cooling-heating system is proposed to resolve the extreme rise and fall of vehicle cabin temperature without running the engine or using any power from the primary source. And, the thermal performance of the proposed system is evaluated and assessed in the numerical study. The proposed system was able to reduce the average temperature of the cabin space by 17 °C in summer season and the average temperature rise of the cabin space is found by 15 °C in winter season. The solar simulator for the vehicle rooftop solar panel investigated annual averages of normalized energy per day and loss in solar energy collection due to variation in tilt angle, which was around 20%. Thus, the present study demonstrates the feasibility of proposed novel solar assisted thermoelectric cooling/heating system in both summer and winter seasons. Hence, study demonstrates that the thermoelectric technology with solar assistance is effective and viable for cooling and heating of vehicle cabin during parking.

Decarbonizing the Cold Chain: Long-Haul Refrigerated Deliveries with On-Board Photovoltaic Energy Integration

Decarbonizing the cold chain is a priority for sustainability due to the increasing demand for chilled/frozen food and pharmaceutics. Refrigerated transport requires additional fuel for refrigeration other than for traction. Photovoltaic panels on the vehicle rooftop, a battery bank, and a power conversion system can replace the diesel engine driving the transport refrigerated unit. In long-haul deliveries, vehicles cross zones with different climate conditions, which affect both refrigeration requirements and photovoltaic energy conversion. Mandatory driver’s breaks and rest also affect delivery timing and energy consumption. A multiperiod, multizone optimization model is developed to size the onboard photovoltaic system, based on features of the delivery tour. The model is applied to a palletized chilled food delivery from North-Eastern Italy, showing a payback time of around four years, which can drop under two years for expected reduction of component costs. Economic and environmental performances can be increased by also allowing refrigerated products on-board during the return journey, leading to more fuel savings. Photovoltaic-integrated long-haul delivery for frozen products is not convenient at current market costs. Different climate conditions are tested, showing the model ability to act as a decision support tool to foster renewable energy penetration into the cold chain.

Experimental Analysis of Solar Assisted Refrigerating Electric Vehicle

Most refrigerating systems are driven by an internal combustion engine that increased the conventional vehicle’s oil consumption and tailpipe emissions. The solar-assisted refrigerating electric vehicle (SAREV) system powered by a hybrid energy mode has been designed. The hybrid energy (solar + grid) was stored in the battery bank to complete this vehicle’s necessary functions. The PV panels are prominently incorporated into this vehicle rooftop to charge the battery bank. In this study, the integrated system was driven by a hybrid energy mode that reducing the wastage and deterioration during temporary storage and transportation in different areas. The performance of the integrated system was tested under different operating conditions. The effect of load variation on maximum speed and travelling distance of vehicle was analyzed. The battery bank charging and discharge performance were studied with and without solar energy. The refrigerator was consuming 116 Wh energy per day to maintain a -12 oC lower temperature on the no-load condition at the higher thermostat position. The refrigerator was run continuously for 4-6 days on battery bank energy and 7-10 days on the full load condition of hybrid energy. The vehicle was travelling at a maximum of 23 km/h speed on full load condition. The vehicle needed torque 14-16 N-m at the initial phase for each load condition. Torque demand was decreasing with the increasing speed of the vehicle. The full-charged battery bank’s initial voltage was 51.04 V, and the cut-off voltage was 46.51 V. The vehicle was covering a distance of 62.4 km with the battery bank alone at full load condition. It was travelling 68.3 km distance with hybrid energy mode. The vehicle’s integrated system was the best in maintaining battery performance, power contribution capability, and drive range enhancement.

Development of a Performance Evaluation Protocol for Air Sensors Deployed on a Google Street View Car

Performance evaluation studies of low-cost sensors (LCS) measuring air pollutants have been conducted by academic and governmental groups for stationary applications. In contrast, evaluation protocols are nonexistent for LCS used in mobile deployments, though LCS are used in this manner by research groups and may be employed to complement regulatory directives for community monitoring. Mobile measurements with LCS are a nascent but growing use-case, and questions of data quality will become increasingly important. The South Coast Air Quality Management District's Air Quality Sensor Performance Evaluation Center has developed the first evaluation protocol in which LCS are compared to reference- or research-grade instruments while deployed on a ground-based mobile platform. LCS are assessed in test scenarios of various degrees of environmental control, ranging from placement in a controlled flow sampling duct to unsheltered mounting on a vehicle rooftop. The testing procedures aim to quantify the performance of LCS and the effects of sensor siting, orientation, and vehicle velocity, the results of which can guide users on appropriate LCS and configurations for their applications. Unexpected performance effects have been revealed through pilot-testing of this evaluation protocol that would likely have not been known from stationary field and laboratory testing.

Design validation and analysis of the drive range enhancement and battery bank deration in electric vehicle integrated with split power solar source

Solar panels are prominently incorporated into electric vehicle rooftop to charge the battery bank. In this paper, the analytical design of two solar electric vehicle models powered with split power solar source architecture and conventional solar power source architecture are presented. The operational behavior of the analytically designed solar electric vehicle models is validated using Matlab. The superiority between split power solar source and conventional solar power source in terms of power contribution capability to the electric vehicle battery bank is analysed under real-time conditions using PVsyst real-time simulator. Further, the drive range enhancement and battery bank deration rate in the two solar EV models due to the incorporation of solar power source is analysed and compared for real-time conditions. Finally, the results of the superior solar electric vehicle model are validated through experimental construction and testing of the model. The comparative study concludes that solar electric vehicle model powered with split power solar source architecture is the best in terms of maintaining battery performance, power contribution capability and drive range enhancement.

Compact and Multiband MIMO Dielectric Resonator Antenna for Automotive LTE Communications

A compact and multiband dielectric resonator antenna (DRA) designed for LTE automotive solutions is presented in this paper. The proposed MIMO system is located on the vehicle rooftop within a limited space of 120 mm × 70 mm × 65 mm. To cover all the LTE standard frequency bands used around the world, the antenna is matched around 790 MHz–860 MHz, 1700 MHz–2200 MHz, and 2500 MHz–2700 MHz frequency bands with a ∣S11∣ lower than −6 dB while presenting a minimum total efficiency of 50% with a maximum realized gain better than 1 dB on all these frequency bands. The DRA is then mounted and measured on a real vehicle rooftop in order to see its performances in real operation conditions. Finally, to improve both the quality and reliability of the wireless link, two DRAs are placed within a small area to reconfigure their radiation patterns on each frequency band. Measured performances, which are in good agreement with the simulated results, are used to validate if the antenna design is suitable for LTE MIMO systems to be integrated on an automotive. The MIMO system is evaluated using the envelope correlation coefficient (ECC), and the obtained value for the proposed antenna is lower than 0.25.

Design, construction, testing and performance of split power solar source using mirror photovoltaic glass for electric vehicles

Solar photovoltaic panels are prominently integrated into electric vehicle rooftop to charge the battery bank. In this paper, the performance of the conventional solar power source architecture employed in electric vehicles is analyzed using PVsyst real-time simulator. The limitations with solar photovoltaic panels and conventional solar power source are addressed through a novel mirror photovoltaic glass and split power solar source architecture. The design, manufacturing and structural merits of split power solar source are presented. The operational behavior of split power solar source is validated using Matlab. The performance of the mirror photovoltaic glass is analyzed at standard test conditions and various combinations of irradiation and temperatures using climate chamber solar simulator. The performance of mirror photovoltaic glass at on-site conditions is analyzed by comparing with climate chamber solar simulator results. Further, the analysis is validated through a convection analysis carried out using ANSYS. Subsequently, the performance of the split power solar source is studied using PVsyst real-time simulator. The split power source architecture is obtained as the best feasible solar power source design for an electric vehicle in terms of material requirement, replacement cost, withstanding capability, space utilization, power loss, tracking mechanism feasibility and performance through the comparative study.

Experimental evaluation of theperformance of 2×2 MIMO-OFDM for vehicle-to-infrastructure communications

In this paper, a novel 2×2 multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) testbed based on an Analog Devices AD9361 highly integrated radio frequency (RF) agile transceiver was specifically implemented for the purpose of estimating and analyzing MIMO-OFDM channel capacity in vehicle-to-infrastructure (V2I) environments using the 920 MHz industrial, scientific, and medical (ISM) band. We implemented two-dimensional discrete cosine transform-based filtering to reduce the channel estimation errors and show its effectiveness on our measurement results. We have also analyzed the effects of channel estimation error on the MIMO channel capacity by simulation. Three different scenarios of subcarrier spacing were investigated which correspond to IEEE 802.11p, Long-Term Evolution (LTE), and Digital Video Broadcasting Terrestrial (DVB-T)(2k) standards. An extensive MIMO-OFDM V2I channel measurement campaign was performed in a suburban environment. Analysis of the measured MIMO channel capacity results as a function of the transmitter-to-receiver (TX-RX) separation distance up to 250 m shows that the variance of the MIMO channel capacity is larger for the near-range line-of-sight (LOS) scenarios than for the long-range non-LOS cases, using a fixed receiver signal-to-noise ratio (SNR) criterion. We observed that the largest capacity values were achieved at LOS propagation despite the common assumption of a degenerated MIMO channel in LOS. We consider that this is due to the large angular spacing between MIMO subchannels which occurs when the receiver vehicle rooftop antennas pass by the fixed transmitter antennas at close range, causing MIMO subchannels to be orthogonal. In addition, analysis on the effects of different subcarrier spacings on MIMO-OFDM channel capacity showed negligible differences in mean channel capacity for the subcarrier spacing range investigated. Measured channels described in this paper are available on request.

A Four-Beam Pattern Reconfigurable Yagi-Uda Antenna

This communication presents a pattern reconfigurable antenna which is based on the Yagi-Uda configuration that can change the radiation beam into four directions. The function of the parasitic elements can be altered between a director and a reflector with PIN diodes while the driven element can be altered between two perpendicular directions with RF switches. To be able to use this proposed antenna on an electric conductor, such as on the vehicle rooftop, the antenna is thus mounted on electromagnetic band gap (EBG) structure which serves as a magnetic conductor. The gain is approximately 5 dBi and the field trial exhibited the diversity gain of 17 dB over the fixed beam antenna. As a result, the proposed antenna possesses high potential for further development into a TV signal reception on moving vehicles.

Broadband high‐efficiency microstrip antenna array with corporate‐series‐feed

AbstractA linearly polarized microstrip antenna array in the Ku‐band achieves high efficiency by having the proper impedance matching throughout the array and by properly using the corporate and series feeds with microstrip transmission lines. The efficiency of the antenna array is 83.3%. The cavity‐backed microstrip patch is used as the element of the antenna array to obtain relatively wide bandwidth. The auto‐tracking antenna in the azimuth direction is developed with a very low profile as well as a low manufacturing cost for the vehicle's rooftop mounting. The main beam of array is tilted 15° away from the broadside direction to provide optimum coverage for Korea satellite III. The measured gain of an antenna array is 23.8 dBi at the center frequency of 12.5 GHz. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 181–183, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20413

Microstrip Yagi array antenna for mobile satellite vehicle application

A novel antenna structure formed by combining the Yagi-Uda array concept and the microstrip radiator technique is discussed. This antenna, called the microstrip Yagi array, has been developed for the mobile satellite (MSAT) system as a low-profile, low-cost, and mechanically steered medium-gain land-vehicle antenna. With the antenna's active patches (driven elements) and parasitic patches (reflector and director elements) located on the same horizontal plane, the main beam of the array can be tilted, by the effect of mutual coupling, in the elevation direction providing optimal coverage for users in the continental United States. Because the parasitic patches are not connected to any of the lossy RF power distributing circuit the antenna is an efficient radiating system. With the complete monopulse beamforming and power distributing circuits etched on a single thin stripline board underneath the microstrip Yagi array, the overall L-band antenna system has achieved a very low profile for vehicle rooftop mounting, as well as a low manufacturing cost. Experimental results demonstrate the performance of this antenna. >

Circular array of outward sloping monopoles for vehicular diversity antennas

A circular array of outward-sloping monopoles is analyzed as a diversity antenna for vehicle rooftop mounting. The monopoles are assumed to approximate minimum scattering antennas, have sinusoidal current distributions, and reside on an infinite, perfectly conducting ground plane. The envelopes of the received signals are considered Rayleigh distributed. The advantage of the array configuration is that the feedpoint spacing can be made almost arbitrarily small, even for a large number of branches. A three-element array with element lengths of 0.6 wavelengths and feedpoint spacing 0.1 wavelengths operating at 463 MHz was field-tested and the results are in good agreement with the analysis.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>