2B Technologies (United States)

Teleoperation is emerging as a key enabler for deploying automated vehicles in safety-critical environments where full autonomy is not yet feasible. Ensuring safety in such systems is challenging due to their reliance on, for example, human operators, wireless communication networks, mixed-traffic interactions, and onboard automated systems, as well as the interdependencies among these components that can trigger cascading failures. To address this, we present a case study on the safety analysis of teleoperated driving in underground mines. We model the teleoperation architecture using a Dynamic Fault Tree (DFT), an extension of traditional static fault trees with explicit modeling support for functional dependencies, order-dependent failures, and redundancy mechanisms. The DFT model is rigorously evaluated through probabilistic model checking across a broad range of system-wide metrics, including degradation behavior and criticality of components. The results provide insights into system reliability, the sensitivity of failure probabilities with respect to different component failure rates, and the behavior of the system in fully functional, fail-operational, and degraded modes. Overall, the findings highlight the critical components that dictate system dependability and establish a structured basis for enhancing the safety of teleoperated vehicle systems to comply with industrial safety standards.

The vehicle routing problem with two-dimensional loading constraints (2L-CVRP) and the last-in-first-out (LIFO) rule presents significant practical and algorithmic challenges. While numerous heuristic approaches have been proposed to address its complexity, stemming from two NP-hard problems: the vehicle routing problem (VRP) and the two-dimensional bin packing problem (2D-BPP), less attention has been paid to developing exact algorithms. Bridging this gap, this article presents an exact algorithm that integrates advanced machine learning techniques, specifically a novel combination of attention and recurrence mechanisms. This integration accelerates the state-of-the-art exact algorithm by a median of 29.79% across various problem instances. Moreover, the proposed algorithm successfully resolves an open instance in the standard test-bed, demonstrating significant improvements brought about by the incorporation of machine learning models. Code is available at https://github.com/xyfffff/NCG-for-2L-CVRP.

ABSTRACTUnderstanding nitrogen oxides (NOx = NO + NO2) measurement techniques is important as air-quality standards become more stringent, important sources change, and instrumentation develops. NOx observations are compared in two environments: source testing from the combustion of Southwestern biomass fuels, and urban, ambient NOx. The latter occurred in the urban core of Albuquerque, NM, at an EPA NCORE site during February–March 2017, a relatively clean photochemical environment with ozone (O3) <60 ppb for all but 6 hr. We compare two techniques used to measure NOx in biomass smoke during biomass burning source testing: light absorption at 405 nm and a traditional chemiluminescence monitor. Two additional oxides of nitrogen techniques were added in urban measurements: a cavity attenuated phase shift instrument for direct NO2, and the NOy chemiluminescence instrument (conversion of NOy to NO by molybdenum catalyst). We find agreement similar to laboratory standards for NOx, NO2, and NO comparing all four instruments (R2 > 0.97, slopes between 0.95 and 1.01, intercepts < 2 ppb for 1-hr averages) in the slowly varying ambient setting. Little evidence for significant interferences in NO2 measurements was observed in comparing techniques in late-winter urban Albuquerque. This was also confirmed by negligible NOz contributions as measured with an NOy instrument. For the rapidly varying (1-min) higher NOx concentrations in biomass smoke source testing, larger variability characterized chemiluminescence and absorption instruments. Differences between the two instruments were both positive and negative and occurred for total NOx, NO, and NO2. Nonetheless, integrating the NOx signals over an entire burn experiment and comparing 95 combustion experiments, showed little evidence for large systematic influences of possible interfering species biasing the methods. For concentrations of <2 ppm, a comparison of burn integrated NOx, NO2, and NO yielded slopes of 0.94 to 0.96, R2 of 0.83 to 0.93, and intercepts of 8 to 25 ppb. We attribute the latter, at least in part, to significant noise particularly at low NOx concentrations, resulting from short averaging times during highly dynamic lab burns. Discrepancies between instruments as indicated by the intercepts urge caution with oxides of nitrogen measurements at concentrations <50 ppb for rapidly changing conditions.Implications: Multiple NOx measurement methods were employed to measure NOx concentrations at an EPA NCORE site in Albuquerque, NM, and in smoke produced by the combustion of Southwestern biomass fuels. Agreement shown during intercomparison of these NOx techniques indicated little evidence of significant interfering species biasing the methods in these two environments. Instrument agreement is important to understand for accurately characterizing ambient NOx conditions in a range of environments.

Ridesharing is a natural option for increasing the efficiency and availability of transportation, and many factors need to align for ridesharing to successfully meet user needs in the marketplace. This paper explains how some of these issues have been addressed in the creation of GrabShare, a realtime ridesharing service available in an increasing number of Southeast Asian cities including Singapore, Manila, Kuala Lumpur, and Jakarta. From an algorithmic point of view, the central topic is the scheduling system, which, given passenger bookings and vehicle locations, assigns passengers to vehicles and creates routes for those vehicles to follow. Other crucial factors include pricing, a navigable and reliable user experience, a system architecture robust to rejections and cancellations, and computationally tractable use of maps and traffic resources. A continuing dedication to understanding each city's individual needs and challenges, and persistent attention to user feedback, is also vital. This paper gives an account of these areas, and attempts to give an organic overview of how GrabShare helps to serve customers as part of an integrated suite of transportation services throughout Southeast Asia.

Abstract. Alkenes are reactive hydrocarbons that influence local and regional atmospheric chemistry, playing important roles in the photochemical production of tropospheric ozone and in the formation of secondary organic aerosols. The simplest alkene, ethene (ethylene), is a major plant hormone and ripening agent for agricultural commodities. The group of light alkenes (C2-C4) originates from both biogenic and anthropogenic sources, but their biogenic sources are poorly characterized, with limited field-based flux observations. Here we report net ecosystem fluxes of light alkenes and isoprene from a semi-arid ponderosa pine forest in the Rocky Mountains of Colorado, USA using the relaxed eddy accumulation (REA) technique during the summer of 2014. Ethene, propene and butene emissions have significant diurnal cycles, with maximum emissions at midday. The fluxes were correlated with each other and followed general ecosystem trends of CO2, water vapor, light and temperature. The light alkenes contribute significantly to the overall biogenic source of reactive hydrocarbons, roughly 15 % of the dominant biogenic VOC, 2-methyl-3-buten-2-ol. The measured ecosystem scale fluxes are nearly twice as large as estimates used in global emissions models for this type of ecosystem.

This article reports a discourse analysis of journals from adult learners during a 1-week residency in Cape Town, South Africa. The theoretical posture is a critical dialogic perspective, making use of a postcolonial understanding of intercultural interactions. The purpose of the study was exploratory. The analysis suggests that demographic variables (e.g., race), prior international travel, and experiences during the residency influence the amount and pace of cognitive change. Results include both questions for future research and suggestions for educators.

Abstract A computer model has been developed to investigate the potential effects of water injection in an offshore oilfield on H2S biogeneration and its subsequent production from the reservoir. The model is based on mechanistic algorithms employed in previous reservoir souring models developed for the Prudhoe Bay and Kuparuk River Fields (Alaska) and the Ekofisk Field (Norway). These mechanisms include the biogeneration of H2S, the partitioning of H2S between oil and water in the waterflooded portions of the reservoir, the reaction of dissolved H2S with siderite to form immobile iron sulfides, and the transport of H2S, oil, water, and gas to producing wells. The reservoir is currently being seawater flooded although produced water reinjection (PWRI) will soon be initiated. In mid-2006, after less than three years of waterflood at relatively low injection rates, H2S was detected in the gas of several producing wells located close to injectors. It is known that PWRI will result in increased H2S production. The model was initially calibrated via history match to determine algorithm coefficients associated with siderite scavenging and microbial nutrient availability within the reservoir during seawater flooding. This calibration required historical produced water sulfate concentrations and H2S mass production rates in order to ascertain actual biogenic sulfate reduction levels and the remaining amount of H2S scavenged by the siderite following its partitioning to reservoir fluids. Results indicate that while scavenging by the siderite is likely occurring at a relatively high level, the H2S production rate will increase significantly once water injection rates are increased and PWRI begins. This paper presents insight as to the importance of water geochemistry in the reservoir souring process and the potential for siderite reactivity, distribution and availability to affect H2S production.

We have built a coupled master oscillator and a slave oscillator optical parametric oscillator (OPO) system that provides single-frequency, pulsed radiation in the midwave infrared (MWIR). The direct-diode-pumped master OPO provided narrow-band (<6-MHz, instrument-limited), tunable MWIR cw radiation that was used to seed a higher-peak-power pulsed slave OPO. When seeded directly at the MWIR idler, the pulsed output of the slave OPO was constrained to oscillate on a single longitudinal mode even though the slave OPO is pumped by a multilongitudinal-mode laser source. The linewidth of the pulsed output has been measured to be <220 MHz (instrument limited), which is well suited for coherent differential absorption lidar applications.

Abstract A relatively simple biofilm column to study biogenic sulfide inhibition under dynamic (flow) conditions is described. Results of studies aimed at evaluating anthraquinone, a biostatic inhibitor of sulfate-reducing bacteria, in simulated oilfield water treatment conditions are presented. The study results have indicated that the biofilm columns are an excellent screening tool for assessing the effects of interactions between oilfield water treatment chemicals on biofilm activity. Anthraquinone was found to be a very effective inhibitor of sulfide production. Co-treatments or sequential treatments with specific oilfield chemicals were found to synergistically increase efficacy, while others were detrimental. Contact of anthraquinone-treated biofilms by crude oil was found to limit sulfide inhibition, although short-term efficacy was unaffected. Anthraquinone was found to biodegrade in the biofilm, apparently leading to the decrease in effectiveness with time.