Browse Topic: Buses
Fuel cell systems have achieved a significant level of technological maturity in ground-based mobility over the past two decades. In particular, commercially available fuel cell propulsion systems are now in serial production for passenger cars and city buses, and are already in regular commercial operation. In the segment of heavy-duty vehicles - such as trucks and other long-haul applications - small-series production and technology demonstrators are currently available and are on the verge of entering the mainstream market. These developments have resulted in well-proven system architectures, sophisticated balance-of-plant components, and established supply chains. In contrast, the utilization of fuel cell propulsion in aviation is still at a very early stage. At present, only a handful of individual prototypes and technology demonstrators - mostly for small aircraft - exist, while serial production remains far in the future. Particularly in the field of lightweight, small, electrical vertical take-off and landing (eVTOL) aircraft there is a unique opportunity to leverage the proven fuel cell systems developed for ground vehicles, adapt them, and further develop them to meet aviation-specific requirements. Such an approach can shorten development timelines and reduce technical risks. Transferring existing fuel cell technologies into aviation, however, is far from a straightforward process. One decisive difference lies in the required specific power density. Aircraft - especially eVTOL - demand significantly higher power densities than those delivered by current commercial fuel cell systems from the automotive sector. This requires a direct adjustment of the stack design and system architecture. Likewise, thermal management poses particular challenges. Whereas piston engines and gas turbines discharge a large portion of their waste heat via exhaust gases, fuel cells must remove all waste heat directly through their cooling systems. This requires efficient radiators capable of transferring heat from the coolant to ambient air. Larger radiator surfaces, however, increase both total aircraft mass and aerodynamic drag, making compact radiator designs essential for aviation applications.
This paper proposes HaloBus, an innovative, edge-computing solution designed to mitigate this risk by detecting student boarding and exiting in real time using lightweight AI based methods. A persistent challenge in elementary school transportation is the issue of missing students after they exit their buses, which disproportionately impacts low-income households. Current safety systems place the burden of implementation on individual households, often requiring independent methods. Common methods include applications on a personal device or a small tracker. However, not everyone can afford these options, and ensuring child safety is a primary concern for parents and caregivers. That is why HaloBus was invented. The system employs YOLOv5us—an Ultralytics-enhanced, anchor-free, split-head architecture that offers a superior accuracy speed trade-off. By providing real-time, on-device alerts, HaloBus enables immediate intervention to prevent a student from being left behind, thereby shifting the focus from reactive post-incident response to proactive safety. Trained on over 70,000 labeled and unlabeled images, the model can accurately detect multiple students simultaneously, significantly reducing false positives. In real-world deployment, the model sustained 30 frames per second on the Raspberry Pi and achieved detection confidence levels exceeding 75% even when subjects wore sunglasses or hoodies. With opt-in participation for each family, HaloBus effectively balances detection efficiency and privacy protection. Overall, HaloBus offers a low-cost, scalable, and ethically conscious approach to enhancing school-bus safety by delivering reliable, on-device boarding and exit detection for multiple students in varied real-world conditions.
This paper explains the method of precooling of electric vehicle from grid connected charger reduce load on HVAC and improve the range. HVAC systems are integral part of a commercial EV bus. With the rise of ambient temperatures during various seasons, the load on HVAC System is increasing. Once an Electric vehicle is released from a depot for service, with an initial soaked up ambient vehicle, the HVAC system demands peak power for cooling the interiors which consumes a lot of battery power thus affecting the range. That cause the additional energy consumption required for precooling, which cannot be estimated as it is highly dependent on ambient temperature and range of the vehicle is also dependent on HVAC consumption during summer and peak loads. This paper is proposing a method that uses a special precooling mode which is activated depending on the selection of the vehicle route based on backend application running on cloud. The Application in the cloud checks if the vehicle is charging and also collects all the information about the SOC. This method will help in reduction in power demand from HVAC unit also helps in increasing the range of the vehicle.
With the continuous development of avionics systems towards greater integration and modularization, traditional aircraft buses such as ARINC 429 and MIL-STD-1553B are increasingly facing challenges in meeting the demanding requirements of next-generation avionics systems. These traditional buses struggle to provide sufficient bandwidth efficiency, real-time performance, and scalability for modern avionics applications. In response to these limitations, AFDX (Avionics Full-Duplex Switched Ethernet), a deterministic network architecture based on the ARINC 664 standard, has emerged as a critical solution for enabling high-speed data communication in avionics systems. The AFDX architecture offers several advantages, including a dual-redundant network topology, a Virtual Link (VL) isolation mechanism, and well-defined bandwidth allocation strategies, all of which contribute to its robustness and reliability. However, with the increasing complexity of onboard networks and multi-tasking scenarios, the existing AFDX protocol still faces challenges in certain areas. Notably, there are issues related to latency jitter control under extreme network loads, efficiency in redundant link dynamic switching, and the assurance of timely and safe transmission of mixed criticality data. To address these challenges, this paper proposes an enhanced data transmission mechanism that builds upon an improved AFDX architecture. This mechanism introduces the construction of Virtual Links, creating a point-to-point network that provides deterministic Quality of Service (QoS) guarantees. Furthermore, a parallel redundant structure is incorporated to further enhance the reliability and fault tolerance of data transmission, ensuring that critical data is transmitted accurately and efficiently in complex, high-demand environments. This research aims to optimize the overall performance of AFDX systems, supporting the evolving needs of modern avionics networks.
In the commercial and off-highway vehicle industry, the transition from internal combustion engines to hybrid and electric alternatives is underway. In 2024, sales of electrified trucks reached more than 97,000, while buses notched 72,000 sales, according to the International Energy Agency (IEA). Estimates for 2025 suggest these numbers will be even greater.
The interaction of electric, electronic (E/E) and mechanical components defines the quality of a BEV’s powertrain. Component selection, their integration and calibration aim at meeting legal requirements for EMC and safety as well as competitive targets for efficiency, NVH and driving comfort. These tasks in particular need attention on electromagnetic events on the DC bus, the high-power electronics of inverters, the e-motors, and the drive shaft. Each component within this environment is defined by its electromechanical features with variabilities selected from a large set of operating parameters. Consequently, a complete powertrain and its controllers give rise to endless combinations for powertrain operation. How to understand and avoid risk laden and ineffective parameter options, how to find powertrain control parameters for safe, efficient and comfortable operation? And how to find solutions within competitive development timeframes? Particular issues include high voltage risks on AC and DC bus, AC resonant ripple currents on the DC lines, or risks arising from powertrain dynamics and impacting NVH quality and driving comfort. Such issues are addressed with extensive system simulations and, finally, with comprehensive testing a powertrain’s electric, electronic and mechanical behavior. The focus of this paper is on E/E and NVH signal analytics guiding the integration of powertrain modules: E/E challenges arise from voltage bursts at MHz frequencies endangering insulation of stator windings and cables. Current ripples on the HV-DC bus may endanger auxiliary components. Motor operation and drive shaft dynamics must not compromise NVH quality and component durability.
This research addresses the issue of noise, vibration, and harshness (NVH) in electric buses, which can hinder their widespread adoption despite their environmental benefits. With the absence of traditional engines, NVH control in electric vehicles focuses on auxiliary components like the air compressor. In this study, the air compressor was identified as a major source of vibration, causing harsh contact between its oil sumps and mounting bracket. Analyzing the vibrations revealed that the sump and bracket were not moving freely, increasing noise. Modifying the bracket design to allow more movement between the components successfully reduced both noise and vibration. The paper details the experimental process, findings, and structural damping methods to mitigate NVH in electric buses.
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