Emergency driving scenarios typically demand longitudinal and lateral forces from tyres to slow the vehicle while performing an obstacle-avoidance manoeuvre. There is sufficient research on pure braking and pure cornering; however, in practice, braking and cornering are rarely performed independently. Active control systems such as Anti-lock Brakes (ABS) and Electronic Stability Control (ESC) react after detecting potential loss of yaw stability and are generally not effective for rollover prevention. A preventative approach is needed to manipulate load transfer and maximise tyre contact before tyre force limits are exceeded. This study investigates the use of a semi-active suspension system to improve rollover-prone, off-road vehicle performance during combined slip manoeuvres. By adjusting suspension characteristics, the system manipulates load transfer and improves overall traction limits, reducing instability and rollover risk. The methodology utilises a high-centre-of-mass off-road vehicle equipped with semi-active suspension alongside a high-fidelity multibody dynamics model for parametric studies. The model is validated through experimental open-loop manoeuvres using brake and steering robots. Findings indicate that the semi-active suspension, switched to hard front and soft rear settings, effectively improves combined slip performance and has the potential to mitigate rollover. Although currently tested on smooth surfaces, this research establishes a vital foundation for future off-road applications where terrain variability poses more severe stability challenges.
Artisanal and small-scale gold mining (ASGM) is increasingly central to rural livelihoods in Zimbabwe amid unemployment and declining agricultural viability driven by climate change. However, in a context characterised by uneven access to technology, capital, and contested resource governance, ASGM assumes a socially differentiated and politically contested character with far-reaching implications for livelihood trajectories. Drawing on qualitative data from interviews, focus group discussions, and archaeological surface survey walks in Shurugwi, Zimbabwe, this article analyses how everyday mining practices, technological adoption, and socio-political relations shape livelihood dynamics. Using a historical materialist lens, the study shows that differential access to processing technologies and means of production structures participation and reward within the mining economy. Informal arrangements function as adaptive governance mechanisms regulating access to labour, markets, and claims amid regulatory ambiguity. Overall, ASGM emerges as a contradictory livelihood system that simultaneously enables accumulation, survival, and precarity, underscoring livelihoods as contested processes embedded in evolving socio-technical and political relations of production.
Abstract Crumb rubber concrete (CRC) is increasingly recognized as a sustainable construction material due to its environmental benefits and potential mechanical performance. However, achieving consistent CRC strength remains challenging, partly due to limited attention to crumb rubber aggregate (CRA) gradation, particle characteristics, and replacement techniques. This study introduces a novel Total Gradation Deviation (TGD) metric to optimize the aggregate packing and enhance mix-design consistency—an aspect that is largely overlooked in most existing CRC research. Additionally, by using 10%–30% finely graded CRA (0.6–4.75 mm), this study offers a more integrated analysis than typically reported in the literature. The findings reveal that compressive strength ( f c ′ ) and density reductions are influenced by not just CRA size but also the effective rubber dosage, specific gravity variation, and gradation alignment. These factors, which are often neglected, partially explain the inconsistent f c ′ results reported in the literature across different studies. As a result, conventional replacement methods become problematic, frequently leading to misleading reductions in strength. Whereas the finer CRA particles ( < 1.2 mm ) enhanced the f c ′ by 5–6 MPa (i.e., 16%–30% increment) due to improved packing and reduced porosity, the broader CRA size distributions (0–5 mm) yielded moderate but structurally acceptable strength ( > 20 MPa ) that aligns with international standards. Optimized mix-designs with a sand-to-aggregate ratio (SAR) of 0.48–0.51, CRA-to-cement ratio < 0.12 , and TGD less than 14% achieved 30–35 MPa, yielding up to 36% f c ′ gain compared to untreated CRA mixes reported in the literature. Overall, these findings offer an invaluable practical, low-cost alternative to other chemical pretreatment methods and support a shift toward more standardized, gradation-based CRC mix-designs that lays a foundation for future work on unified performance indices, environmental modeling, and microscale validation.
This study examines why entrepreneurship education in Sub-Saharan Africa persists despite limited demonstrable impact. Drawing on institutional and compensatory entrepreneurship theory, we conduct a multi-level abductive study across Ghana, Nigeria, South Africa, and Zambia using 59 interviews with students, faculty, policymakers, and administrators. We show how entrepreneurship education operates as a compensatory legitimacy mechanism linking policy mandates, institutional compliance, and student dissatisfaction. Under conditions of resource constraint and high unemployment, symbolic implementation sustains governmental and university legitimacy despite weak outcomes. We specify the boundary conditions under which entrepreneurship education is likely to function symbolically rather than instrumentally and offer implications for policy design in resource-constrained contexts.
