On-board Experiments Research Articles

A Comprehensive Implementation of Road Surface Classification for Vehicle Driving Assistance: Dataset, Models, and Deployment

The prior monitoring of the road surface conditions provides valuable information to vehicle trajectory planning and active control systems. Road surface perception with vision sensors is an emerging technology that has recently gained much attention. However, there are few reports on an exhaustive technical scheme and application practice for driving assistance. This study first creates a large-scale road surface image dataset containing one million samples with detailed road friction level, material, and unevenness level annotations. A convolutional neural network (CNN) classification model constrained by a combined loss function and adapted optimization strategies is trained on the dataset. Then we propose a decision-level fusion method based on the improved Dempster-Shafer evidence theory to enhance the robustness of the classification algorithm. Finally, the developed models are deployed on the embedded hardware platform. The top-1 accuracy for classifying road surface images reaches 92.05% by the CNN model and 97.50% after fusion. Onboard experiments illustrate the advantage and superiority of the developed technical framework, which has excellent potential in real-vehicle applications for driving assistance.

Performance Evaluation of CentiSpace Navigation Augmentation Experiment Satellites

This paper presents the performance analysis of CentiSpace low earth orbit (LEO) experiment satellites. Distinguishing them from other LEO navigation augmentation systems, the co-time and co-frequency (CCST) self-interference suppression technique is employed in CentiSpace to mitigate significant self-interference caused by augmentation signals. Consequently, CentiSpace exhibits the capability of receiving navigation signals from the Global Navigation Satellite System (GNSS) while simultaneously broadcasting augmentation signals within the same frequency bands, thus ensuring excellent compatibility for GNSS receivers. CentiSpace is a pioneering LEO navigation system to successfully complete in-orbit verification of this technique. Leveraging the on-board experiment data, this study analyzes the performance of space-borne GNSS receivers equipped with self-interference suppression and evaluates the quality of navigation augmentation signals. The results show that CentiSpace space-borne GNSS receivers are capable of covering more than 90% visible GNSS satellites and the precision of self-orbit determination is at the centimeter level. Furthermore, the quality of augmentation signals meets the requirements outlined in the BDS interface control documents. These findings underscore the potential of the CentiSpace LEO augmentation system for the establishment of global integrity monitoring and GNSS signal augmentation. Moreover, these results contribute to subsequent research on LEO augmentation techniques.

Simulation of cosmic rays inside an aircraft: spectral perturbation and dose reduction due to aircraft structures and contents.

In this study, an intricate combinatorial geometry model of a Boeing 777-300ER aircraft was constructed for Monte Carlo transport simulations. The aircraft-induced perturbations of the energy spectra and effective doses of secondary cosmic rays at a typical civil aviation altitude (10km) were investigated on a component-by-component basis, which included neutrons, protons, photons, electrons, positrons, muons and charged pions. Two geomagnetic cutoff rigidities (1.35 and 15.53 GV) and two solar modulation parameters (430 and 1360 MV) were considered in the aforementioned simulations. The characteristics of various cosmic-ray components at six locations along the fuselage were assessed and compared with those of an unperturbed radiation field in the atmosphere. Aircraft structures and contents reduced the effective doses of personnel inside the aircraft to varying degrees, up to an ~32% reduction in the middle section of the passenger cabin. On average, the dose reduction was ~12-16% depending on geomagnetic and solar conditions. Quantifying the aircraft's self-shielding effects can further improve the estimation accuracy of aircrew and passengers' exposure to cosmic radiation. Information regarding the perturbed energy spectra of cosmic rays may be useful for designing onboard experiments or analyzing onboard measurement data.

An Improved Differential Evolution Adaptive Fuzzy PID Control Method for Gravity Measurement Stable Platform.

In the platform gravimeter, the stabilization accuracy of the gravimetric stabilization platform is crucial to improve the accuracy of gravity value measurements due to its uncertainties, such as mechanical friction, inter-device coupling interference, and nonlinear disturbances. These cause fluctuations in the gravimetric stabilization platform system parameters and present nonlinear characteristics. To resolve the impact of the above problems on the control performance of the stabilization platform, an improved differential evolutionary adaptive fuzzy PID control (IDEAFC) algorithm is proposed. The proposed enhanced differential evolution algorithm is used to optimize the initial control parameters of the system adaptive fuzzy PID control algorithm to achieve accurate online adjustments of the gravimetric stabilization platform's control parameters when it is subject to external disturbances or state changes and attain a high level of stabilization accuracy. The results of simulation tests, static stability experiments, and swaying experiments on the platform under laboratory conditions, as well as on-board experiments and shipboard experiments, all show that the improved differential evolution adaptive fuzzy PID control algorithm has a higher stability accuracy compared with the conventional control PID algorithm and traditional fuzzy control algorithm, proving the superiority, availability, and effectiveness of the algorithm.

Response of microbial community of surface and deep chlorophyll maximum to nutrients and light in South China Sea

In oligotrophic seas such as South China Sea, the subsurface or deep chlorophyll maximum (DCM) is always present. The surface planktonic community receives sufficient light, but is short of nutrients. The DCM layer is under light limitation, but frequent supply of nutrients. Therefore, vertical mixing becomes critical in determining their community composition and drives their changes by responding to light and nutrients. In this study, we conducted an onboard experiment by collecting seawater samples at surface and the DCM layer and adding nutrients, and incubated them under full sunlight and 10% light, and examined the diversity of bacterial and eukaryotic communities and their cell abundance using 16/18S high throughput sequencing and FCM approaches. Our study found large differences in bacterial and eukaryotic community structure and cell abundance between the surface and DCM. After 72 hours of culture, taxonomically the incubated surface water was dominated by pico-eukaryotic phytoplankton, while the incubated DCM layer water is dominated by diatoms, which suggests diatoms are the main functional group of phytoplankton bloom after a vertical mixing event. These findings indicate that phytoplankton at the DCM respond to enhanced light and frequent supplied nutrients due to vertical mixing and thus maintain primary productivity in the otherwise oligotrophic oceans.

An occlusion- and interaction-aware safe control strategy for autonomous vehicles

We consider the problem of safe autonomous driving in the presence of occlusions. Dealing with latent risks arising from occlusions is challenging because there does not exist direct mapping from sensor input to visible threats; attempts to ensure safety for all worst-case latent threats can be infeasible or overly conservative, and accounting for a multitude of latent risks for sufficient future horizon may require prohibitive computation in real-time. To address these issues, in this paper, we propose to use a probability-based predictive controller to make safe decisions for autonomous vehicles. We prove that the proposed safety controller can generate vehicle control profiles that yield the desired safety probability. Numerical and onboard experiments on a visual occluded pedestrian crossing scenario verifies the efficacy of the proposed method in real-time. The merits of the proposed control strategy include being able to guarantee long-term safety under occlusions without being over-conservative, handling latent risks caused by on-road interactions in real-time, and ease of design with transparency to the exposed risks.

CAGE-ARCLIM cruise: Culturing (sub)Arctic planktic foraminifera Neogloboquadrina pachyderma and Globigerina bulloides: Implications for ocean acidification and paleoceanography reconstructions

From the morning of June 23rd to the morning of June 30th 2022, the Department of Geosciences at UiT the Arctic University of Norway, arranged a scientific cruise on R/V “Helmer Hanssen aimed at sampling living planktic foraminifera (Neogloboquadrina pachyderma and Globigerina bulloides) for culturing experiments both onboard and continued at the culturing laboratory at the Department. The purpose is to investigate the physiological and calcification responses of this species to a wide range of temperature, salinity and carbonate chemistry as well as to establish Arctic-tailored proxy calibrations for paleoceanography reconstructions

CAGE21-2 Cruise Report: Planktic foraminifera sampling for culturing experiments, central Greenland Sea 75°N

From the morning of June 28th to the morning of July 3rd 2021, the Department of Geosciences at UiT The Arctic University of Norway, arranged a scientific cruise on R/V “Helmer Hanssen aimed at sampling living planktic foraminifera (primarily Neogloboquadrina pachyderma) for culturing experiments both onboard and continued at the culturing laboratory at the Department. The purpose is to investigate the physiological and calcification responses of this species to a wide range of temperature, salinity and carbonate chemistry as well as to establish proxy calibration for paleoceanographic reconstructions. The cruise may be known as: CAGE21_2

The impact of marine engine noise exposure on seafarer fatigue: A China case

Previous relevant studies have revealed that noise and poor sleep quality are two important risk factors causing seafarer fatigue. However, the relationship between marine engine noise and objective sleep parameters has rarely been studied. Using primary data collected from a 28-day on-board experiment and 1 questionnaire survey during both voyage and berthing periods, this study takes a pioneering step to address this crucial relationship. Energy indicators related to the engine noise for 28 days were estimated and 6 objective sleep parameters were used to measure the degree of seafarer fatigue. The findings reveal that as seafarers want to sleep longer to relieve their anxiety and irritability caused by the increased engine noise, the time in bed (TB) and the total sleep time (TST) increased when the engine noise level increased. Meanwhile, with the growing engine noise levels and the higher number of engine noise events, the total wake time after sleep onset (WASO) and the time for sleep onset latency (SOL) increased, and the sleep efficiency (SE) decreased. Energy indicators were significantly associated with objective sleep parameters. Finally, strengthening the content of psychological adjustment in the seafarer training link and cultivating the seafarers' character strength to improve the ability to face harsh environments are recommended. In maritime management, managers should play the role of social work intervention to adjust seafarers’ sleep quality and ease fatigue. In the construction of ships, builders should emphatically consider the use of sound insulation materials to reduce noise effect on living areas.

Bayesian Modeling of Crowd Dynamics by Aggregating Multiresolution Observations From UAVs and UGVs

Unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) can be jointly deployed to form a collaborative surveillance system, where UAVs collect low-resolution images at a high altitude to obtain a global perception and UGVs observe high-resolution images within a focused detection range. Such multiresolution heterogeneous observations create opportunities yet pose challenges to model the dynamics of the targeted crowds. Existing approaches that integrate multiresolution observations rely on intensive computation of a large volume of historical data, and thus, result in a lack of computational efficiency, accuracy, and robustness. To address these limitations, this article proposes a new crowd dynamics modeling approach to aggregating the multiresolution information under a Bayesian inference framework. Beta-binomial and Normal–Wishart conjugate distributions were adopted to model crowd dynamics from low-resolution UAV observations and high-resolution UGV observations, respectively. Based on the proposed approach, a real-time model updating mechanism is developed to implement information aggregation for onboard crowd dynamics inference, where high efficiency, accuracy, and robustness are critical. Numerical simulations and onboard experiments were conducted to demonstrate the effectiveness and efficiency of the proposed modeling approach.

Vertical distribution, standing stocks, and taxonomic accounts of the entire plankton community, and the estimation of vertical material flux via faecal pellets in the southern Okhotsk Sea

The faecal pellets egested by zooplankton are essential as they influence the vertical material flux in oceans. As mesozooplankton are dominant within the plankton community in the southern Okhotsk Sea during early summer, the vertical material flux via mesozooplankton is expected to be substantial. However, quantitative information on their faecal pellets is currently lacking. In this study, we evaluated the taxonomic accounts of the entire plankton community, including microplankton, mesozooplankton, and macrozooplankton, in the 0–1000 m water column. The ingestion and egestion rates of the zooplankton were also estimated. We used a fine-mesh (63 μm) plankton net along with an imaging technique (with ZooScan) to quantify the amount of in-situ faecal pellets. Furthermore, on-board experiments were conducted to estimate the faecal pellet egestion by the dominant zooplankton species. Cosmopolitan diatom species were found to dominate the microplankton biomass, whereas the large-sized calanoid copepod Metridia okhotensis, which performs nocturnal ascent diel vertical migration, dominated the mesozooplankton biomass. Two euphausiid species with different body sizes, namely the small-sized Thysanoessa inermis and the large-sized Euphausia pacifica, were found to be dominant among the macrozooplankton. The highest density and mass of faecal pellets (1888 pellets m−3, 2.96 mg C m−3) was observed in the 0–100 m layer during the daytime. Throughout the layer, the volumes of the faecal pellets peaked at 0.010–0.015 mm3, which corresponded with the size of the pellets egested by M. okhotensis in the on-board laboratory experiments. The large-sized faecal pellets (>0.2 mm3), which were inferred to be egested by euphausiids, were only observed during the night-time. Based on the on-board experiments, the faecal pellets egested by all the meso- and macrozooplankton species contained phytoplankton cells that possessed a fluorescent ability. Furthermore, cyanobacteria were the most common taxa (26–65% in number) observed in the faecal pellets. Coprophagy (feeding on faecal pellets) was observed for the calanoid copepod Gaetanus variabilis, which was collected from depths of 500–1000 m. The estimated daily ingestion rates of meso- and macrozooplankton corresponded with 21% of the standing stock of microplankton. In contrast, their daily egestion rates accounted for 40–112% of the in-situ faecal pellet masses. Faecal pellet collection by the gentle vertical towing of a fine-mesh plankton net and quantification through imaging analysis can provide new insights for the evaluation of the number and mass of faecal pellets in the field. The findings of the present study suggest that these techniques have the potential to successfully quantify faecal pellets in the water column.

Research on the operation mechanism and stability of marine textured directional valve

Based on the vibration force analysis of the marine electromagnetic directional valve and Newton’s Second Law, the mathematical model of the displacement of the valve rod under vibration excitation state is established. The influence of vibration parameters and viscous damping coefficient on its operation stability is calculated and analyzed. Results show that the vibration stability can be improved by increasing the clearance viscous damping of the directional valve, and the textured surface affecting on the viscous force and flow resistance characteristics. All of these provide a basis for stability optimization. The on-board experiment of marine electromagnetic directional valve in real-time working condition is operated, the performance difference between the textured and untextured valve is analyzed. The results show that the pressure adjustment time and vibration impact amplitude of two kinds of directional valves decrease with the increase of oil supply pressure, and increase with the increase of navigation speed. The standard deviation of flow fluctuation of untextured directional valve increases with the increase of oil supply pressure, while the flow fluctuation of micro-textured directional valve first decreases and then increases. The unique interface characteristics of the micro-textured directional valve make the pressure adjustment time, the standard deviation of flow pulsation, and the vibration impact amplitude of the micro-textured valve smaller than that of the untextured one.

Planetary Distribution of the Space Radiation Dose Rate Based on Results of the DEPRON Experiment Onboard the Lomonosov Satellite

Planetary Distribution of the Space Radiation Dose Rate Based on Results of the DEPRON Experiment Onboard the Lomonosov Satellite

Biological Response of Planktic Foraminifera to Decline in Seawater pH.

Simple SummaryThe ocean absorbs large amounts of CO2 emitted by human activities, which leads to a decrease in seawater pH, and has the potential to cause damage to calcareous marine organisms. Planktic foraminifera are some of the most important calcareous marine organisms in the ocean, although the biological response of planktic foraminifera to the decline in seawater pH is still unknown. In this study, the biological response of planktic foraminifera to declining seawater pH was studied through a series of on-board experiments. The experimental results showed that the decrease in seawater pH adversely affected the biological processes of planktic foraminifera, resulting in weaker predation, slower growth, lighter shells, and more deformities. In addition, for the first time, we report that microalgae that live with planktic foraminifera were also killed under low-pH conditions. Several indices were established to quantify the relationships between the biological parameters of planktic foraminifera and seawater pH, which could be used to reconstruct the paleoceanographic seawater pH. This study provides experimental data to quantify the biological response of calcareous plankton to a decline in seawater pH.Understanding the way in which a decline in ocean pH can affect calcareous organisms could enhance our ability to predict the impacts of the potential decline in seawater pH on marine ecosystems, and could help to reconstruct the paleoceanographic events over a geological time scale. Planktic foraminifera are among the most important biological proxies for these studies; however, the existing research on planktic foraminifera is almost exclusively based on their geochemical indices, without the inclusion of information on their biological development. Through a series of on-board experiments in the western tropical Pacific (134°33′54″ E, 12°32′47″ N), the present study showed that the symbiont-bearing calcifier Trilobatus sacculifer—a planktic foraminifer—responded rapidly to a decline in seawater pH, including losing symbionts, bleaching, etc. Several indices were established to quantify the relationships between these biological parameters and seawater pH, which could be used to reconstruct the paleoceanographic seawater pH. We further postulated that the loss of symbionts in planktic foraminifera acts as an adaptive response to the stress of low pH. Our results indicate that an ongoing decline in seawater pH may hinder the growth and calcification of planktic foraminifera by altering their biological processes. A reduction in carbonate deposition and predation could have profound effects on the carbon cycle and energy flow in the marine food web.

Sediment Resuspension and Associated Extracellular Enzyme Activities Measured ex situ: A Mechanism for Benthic-Pelagic Coupling in the Deep Gulf of Mexico

Sediment resuspension caused by near-bed currents mediates exchange processes between the seafloor and the overlying water column, known as benthic-pelagic coupling. To investigate the effects of sediment resuspension on microbial enzyme activities in bottom waters (<500 m), we conducted onboard erosion experiments using sediment cores taken with a multi-corer from six deep-sea sites in the northern Gulf of Mexico. We then incubated the core-top water with resuspended sediments in roller tanks to simulate bottom water conditions following sediment resuspension. Bacterial cell abundance, particulate organic matter content, and potential rates of three hydrolytic enzymes (leucine aminopeptidases – PEP; β-glucosidases – GLU, lipases – LIP) were monitored during the experimentally-generated erosion events and subsequently in the roller tanks to examine whether resuspension of deep-sea sediments enhances activities of extracellular enzymes in overlying waters. Surficial sediments were resuspended at critical shear stress velocities between 1.4 and 1.7 cm s–1, which parallel bottom water currents of 28 and 34 cm s–1. Only one of our nine cores resisted experimentally generated bottom shear stresses and remained undisturbed, possibly as a result of oil residues from natural hydrocarbon seeps at the investigated site. The most notable enzymatic responses to sediment resuspension were found for LIP activities that increased in overlying waters of all eight of our resuspended cores and remained at high levels during the roller tank incubations. PEP and GLU showed orders of magnitude lower rates and more variable responses to experimentally resuspended sediments compared with LIP. We also found a disconnect between enzyme activities and bacterial cell numbers, indicating a major role of extracellular enzymes physically disconnected from microbial cells in our experiments. Our results demonstrate that sediment resuspension may promote organic matter breakdown in bottom waters by supplying extracellular enzymes without requiring a bacterial growth response. The marked increase in LIP activity suggests that resuspended enzymes may affect the degradation of petroleum hydrocarbons, including those from the natural seeps that are abundant in the investigation area.

Analysis of Ship Noise Characteristics Generated According to Sailing Conditions of the G/T 1000-ton Stern Fishing Trawler

In this study, we conducted onboard noise measurement experiments under the conditions of anchoring, sailing, casting, and hauling to determine whether noise generated in the G/T 1000-ton fishing trawler triggers zone-specific effects upon vessel operation. It was shown that most accommodation areas of the trawler comfortably met the IMO acceptance criteria regardless of the sailing condition, but most of the stern area, where the fishing actually occurs, exceeded the permitted limit of 75 dB (A). Furthermore, the statistical analysis revealed a significant difference (p < 0.05) only in the bow and the stern, which are both open areas. In the case of the former, improvements were deemed possible due to the influence of the fluid emission noise from the seawater piping in the bow, and the acceptance criteria were also appropriate. However, in the case of the latter, a significant difference was seen in hauling conditions, and on-site analysis confirmed frictional noise from hydraulic oil in the trawl winch and between the chains and the metal hull, leading to the conclusion that various improvements are required, such as the mandatory wearing of safety equipment by workers and stricter legal standards for permitted noise levels.

Heat Loss Analysis of Flow Boiling Experiments Onboard International Space Station with Unclear Thermal Environmental Conditions (2nd Report: Liquid-vapor Two-phase Flow Conditions at Test Section Inlet)

Heat Loss Analysis of Flow Boiling Experiments Onboard International Space Station with Unclear Thermal Environmental Conditions (2nd Report: Liquid-vapor Two-phase Flow Conditions at Test Section Inlet)

Pre-flight Calibration and Near-Earth Commissioning Results of the Mercury Plasma Particle Experiment (MPPE) Onboard MMO (Mio)

BepiColombo Mio (previously called MMO: Mercury Magnetospheric Orbiter) was successfully launched by Ariane 5 from Kourou, French Guiana on October 20, 2018. The Mercury Plasma/Particle Experiment (MPPE) is a comprehensive instrument package onboard Mio spacecraft used for plasma, high-energy particle and energetic neutral atom measurements. It consists of seven sensors including two Mercury Electron Analyzers (MEA1 and MEA2), Mercury Ion Analyzer (MIA), Mass Spectrum Analyzer (MSA), High Energy Particle instrument for electron (HEP-ele), High Energy Particle instrument for ion (HEP-ion), and Energetic Neutrals Analyzer (ENA). Significant efforts were made pre-flight to calibrate all of the MPPE sensors at the appropriate facilities on the ground. High voltage commissioning of MPPE analyzers was successfully performed between June and August 2019 and in February 2020 following the completion of the low voltage commissioning in November 2018. Although all of the MPPE analyzers are now ready to begin observation, the full service performance has been delayed until Mio’s arrival at Mercury. Most of the fields of view (FOVs) of the MPPE analyzers are blocked by the thermal shield surrounding the Mio spacecraft during the cruising phase. Together with other instruments on Mio including Magnetic Field Investigation (MGF) and Plasma Wave Investigation (PWI) that measure plasma field parameters, MPPE will contribute to the comprehensive understanding of the plasma environment around Mercury when BepiColombo/Mio begins observation after arriving at the planet Mercury in December 2025.

Real-world evaluation of driving behaviour and emission performance of motorcycle transportation in developing countries: A case study of Isfahan, Iran

The present study aims at a real-world assessment of the driving behaviour and exhaustive emission performance of motorcycle (MC) driving in a middle-sized city of a developing country, i.e. Isfahan, Iran. We developed the Isfahan Motorcycle Driving Cycle (IMDC) using comprehensive data collection and then compared it with the available overseas MCDCs and DC of local LDVs. Onboard experiments were also conducted on 20 test motorcycles to analyze emission performance, emission characteristics, and combustion quality of motorcycles under real-world conditions. IVE model was used to estimate the MC emission factors (EFs) according to the real-urban conditions, but it was first adjusted to the real-world measurements. Results show that MC EFs steadily decrease with vehicle speeds. Apparent discrepancies were observed between IMDC and the MC DCs overseas, while local DCs of motorcycles and LDVs follow a prevailing trend determined by the new factors of public culture and urban development. CO was the major criteria pollutant of the MCs exhaust, and formaldehyde and benzene were ranked as the first and second principal toxic gases, respectively. The air-fuel mixture control system and combustion quality of 150 and 200 cc MCs were impaired with the vehicle speed, but the same is not true for the 125 cc MCs.

An Improved Single-Epoch Attitude Determination Method for Low-Cost Single-Frequency GNSS Receivers

GNSS attitude determination has been widely used in various navigation and positioning applications, due to its advantages of low cost and high efficiency. The navigation positioning and attitude determination modules in the consumer market mostly use low-cost receivers and face many problems such as large multipath effects, frequent cycle slips and even loss of locks. Ambiguity fixing is the key to GNSS attitude determination and will face more challenges in the complex urban environment. Based on the CLAMBDA algorithm, this paper proposes a CLAMBDA-search algorithm based on the multi-baseline GNSS model. This algorithm improves the existing CLAMBDA method through a fixed geometry constraint among baselines in the vehicle coordinate system. A fixed single-baseline solution reduces two degrees of freedom of vehicle rigid body, and a global minimization search for the ambiguity objective function in the other degree of freedom is conducted to calculate the baseline vector and its Euler angles. In addition, in order to make up for the shortcomings of short baseline ambiguity in complex environments, this paper proposes different validation strategies. Using three low-cost receivers (ublox M8T) and patch antennas, static and dynamic on-board experiments with different baseline length set-ups were carried out in different environments. Both the experiments prove that the method proposed in this paper has greatly improved the ambiguity fixing performance and also the Euler angle calculation accuracy, with an acceptable calculation burden. It is a practical vehicle-mounted attitude determination algorithm.