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Future autonomous transportation systems necessitate network infrastructure capable of accommodating massive vehicular connectivity, despite the scarce availability of frequency resources. Current approaches for achieving such required high spectral efficiency, rely on the utilization of Multiple-Input, Multiple-Output (MIMO) technology. However, conventional MIMO processing approaches, based on linear processing principles, leave much of the system's capacity heavily unexploited. They typically require a large number of powerconsuming antennas and RF-chains to support a substantially smaller number of concurrently connected devices, even when the devices are transmitting at low rates. This translates to inflated operational costs that become substantial, particularly in ultradense, metropolitan-scale deployments. Therefore, the question is how to efficiently harness this unexploited MIMO capacity and fully leverage the available RF infrastructure to maximize device connectivity. Addressing this challenge, this work proposes an Open Radio Access Network (Open-RAN) deployment, with Massively Parallelizable Non-linear (MPNL) MIMO processing for densely deployed, and power-efficient vehicular networks. For the first time, we quantify the substantial gains of MPNL in achieving massive vehicular connectivity with significantly reduced utilized antennas, compared to conventional linear approaches, and without any throughput loss. We find that an Open-RAN-based realization exploiting the MPNL advancements can yield an increase of over 300% in terms of concurrently transmitting single-antenna vehicles in urban mobility settings and for various Vehicle-to-Infrastructure (V2I) and Network (V2N) use cases. In this context, we discuss how implementing MPNL within the Open-RAN ecosystem allows for simpler and more densely deployed radio units, paving the way for fully autonomous and sustainable transportation systems.

A simple conversion of a standard triaxial apparatus for stress path testing is presented and illustrated. The conversion is effected by incorporating a balanced ram arrangement into the top plate of a conventional triaxial cell, which, together with some additional modifications to the sample top cap and ram connection details, provides a cost-effective stress path testing cell. This modified triaxial cell, combined with a suitable external loading frame, allows the axial and radial stresses to be independently controlled. Consequently, any desired stress path can be applied to a specimen mounted in the modified cell. The functionality of the modified cell is demonstrated through the results of long-term stress-path tests performed as part of a creep study of intact medium porosity chalk. In this study, the modified cells were used with cantilever type loading frames, and subjected to continuous loading for periods in excess of 400 days. The performance of the modified cells was very satisfactory, and demonstrates that such an arrangement can provide a simple and a cost-effective system for conducting laboratory stress-path tests.

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