Using gaussian process machine learning to predict dynamic road wear of a rigid heavy vehicle

The paved road network is a critical asset to any economy. South Africa has a paved road network that has an estimated value above R2 trillion. This asset is however under threat as there was a backlog in maintenance of more than R416.6 billion in 2018. Heavy vehicles are primarily responsible for road wear, and overloaded vehicles can cause more than 60% of road wear. Most road wear assessments use static axle loads that are assumed to be symmetrical on either side to calculate the road wear caused by a heavy vehicle. Previous work has shown that the effect of crossfall (CF) cannot be ignored when considering the dynamic road wear of heavy vehicles. This paper expands on previous work through the development of a novel Gaussian process machine learning (GPML) model that can predict the dynamic road wear of a rigid heavy vehicle given 15 input parameters. The road wear criteria considered are the first (1st) and fourth (4th) power aggregate forces on the left and right sides using the 95th and 99th percentile conditions. The results show that the model is very accurate and requires comparatively few inputs to train an accurate model. For interpolated results, the average absolute error is less than 1% and for extrapolated results, the average absolute error is less than 3%. The results also include the standard deviation associated with the result which is important for future research to minimise training examples. Using machine learning models to predict dynamic road wear allows for rapid calculation and testing and also does not require expensive multibody dynamics software tools to calculate. This would be very advantageous to the industry, especially when developed for the Smart Truck Pilot Project.Papers presented at the 40th International Southern African Transport Conference on 04 -08 July 202

Modelling vertical uniform contact stress of heavy vehicle tyres

The field of tyre dynamics is a relatively new, but highly complex field of engineering. The testing and modelling of various tyres in order to determine stress distributions of tyres on the road surface, under varying conditions, remains a relevant and important field of study. The information from these studies are essential to understanding vehicle dynamics as the small contact patches between the vehicle tyres and road surface is the only area of interaction between the entire vehicle and the road surface. The contact stress data is also essential in the calculation of road wear characteristics of tyres and vehicles. Different models exist to estimate the contact stress between the tyre and road surface, but most contain assumptions that limit their applicability to a small set of tyres under very specific load cases. This paper considers the development of mathematical models that are used to estimate the vertical uniform contact stress for three types of heavy vehicle tyres. The three tyres studied are 315/80 R22.5, 385/65 R22.5 and 425/65 R22.5 tyres. The models have been developed through the use of tyre testing data obtained from the Stress-In-Motion (SIM) system. It was found that 4th order polynomials provided the most accurate stress results over the selected operating range of 25 kN to 45 kN which is the typical load range for heavy vehicle tyres due to legal axle load limits. The polynomial formulas require only the tyre inflation pressure and vertical tyre load as inputs, in order to estimate the vertical uniform contact stress. The models developed correlate well with the test data and showing an average absolute error of less than 2 %.Paper presented at the 35th Annual Southern African Transport Conference 4-7 July 2016 "Transport ? a catalyst for socio-economic growth and development opportunities to improve quality of life", CSIR International Convention Centre, Pretoria, South Africa.The Minister of Transport, South AfricaTransportation Research Board of the US

Operating costs: pbs vs conventional heavy vehicles in south africa

Road transport is a highly competitive industry and is renowned for low profit margins. Road transport however accounts for almost 6% of the Gross Domestic Product (GDP) and is the backbone of the economy. The Performance-Based Standards (PBS) or Smart Truck Pilot project has existed in South Africa since 2007 and monitoring data has shown substantial savings including a 34% reduction in crash rates, 18.3 million litres of fuel and 534 840 trips being saved since the start of the project. The Australian PBS programme is projected to save more than AUS$17 billion by 2034. The potential financial impact of PBS in South Africa has not yet been fully quantified using actual operational costs from operators participating in the trial. In this study a questionnaire was used to collect operational costs from PBS operators and has compared the costs of PBS and baseline vehicles. The most significant finding is that on a per tonne-km basis, the weighted average overall cost savings was 18.8% for the all PBS versus baseline vehicles. Not all PBS operators showed a reduction in operating costs but this could be attributed to having only one PBS vehicle and operating in a specialized industry with short lead distances. PBS however, appears as a viable solution to reduce transport costs, reduce crashes and emissions and also save the road infrastructure and should be considered for regulated implementation in South Africa.Papers presented virtually at the 39th International Southern African Transport Conference on 05 -07 July 202

Nicotiana glauca poisoning in ostriches (Struthio camelus)

Putative Nicotiana glauca (wild tobacco) poisoning was diagnosed in a flock of ostriches near Oudtshoorn, South Africa. Post mortem examinations (n = 7) were performed on ostriches (Struthio camelus) that had died. Suspicious leaf remnants (weighing 80–770 g), packed in a layer on top of other plant material, were carefully separated from the proventricular content and submitted for chemical determination of anabasine, the major toxic principle contained by this plant. A standard solid phase extraction method was used followed by an optimised liquid chromatography-mass spectrometry procedure. Anabasine was detected in the leaf remnants (114–177 μg/g dry weight) removed from the proventriculus of the ostriches that succumbed as well as in control N. glauca leaves (193 μg/g dry weight). The analytical methods used in this study revealed the presence of anabasine in the suspicious leaf remnants, indicating that the birds had been exposed to N. glauca and had died of this poisoning.http://www.journals.co.za/ej/ejour_savet.htm

Benchmarking the Performance of High Capacity Vehicles in South Africa

The Smart Truck or Performance-Based Standards (PBS) pilot project in South Africa has been running since 2007, and currently comprises approximately 280 vehicles operational in seven provinces, spanning fourteen different industries or commodities. These high capacity vehicles operate under special permit concessions, which allow for additional mass and dimensions, but still adhere to the permissible axle loads. Each participating vehicle in this pilot project must be assessed for its vehicle dynamics performance against fifteen performance standards, as well as its road wear impact performance as assessed against eight representative road structures in South Africa. For each PBS vehicle design, the equivalent “baseline” vehicle is also assessed. This is the standard legal vehicle (with no mass or dimension concessions) which performs the same freight task on the same route for the same operator alongside the PBS vehicle. Assessing both PBS and baseline vehicles and logging their operational performance provides insights into the operating cost benefits of PBS vehicles as well as their safety and road impact performance as compared to standard legal vehicles in South Africa. In this paper some of the latest data for both PBS and baseline vehicles will be assessed, and extract insights into heavy vehicle freight transport in South Africa. This comparative study is the first of its kind for the South African PBS pilot project and lays the foundation for important future studies in this area.Papers presented at the 38th International Southern African Transport Conference on "Disruptive transport technologies - is South and Southern Africa ready?" held at CSIR International Convention Centre, Pretoria, South Africa on 8th to 11th July 2019

The Effect of Road Crossfall on Road Wear Caused by Heavy Vehicles

The paved road network is a critical asset to any economy. South Africa has a paved road network that has an estimated value in excess of R2 trillion. This asset is however under threat as there was a backlog in maintenance of more than R197 billion in 2014. Heavy vehicles are primarily responsible for road wear, and overloaded vehicles can cause more than 60% of road wear. Most road wear assessments use static axle loads that are assumed to be symmetrical on either side in order to calculate the road wear caused by a heavy vehicle. This paper investigates the effect of road crossfall on the road wear caused by heavy vehicles, and compares it to the wear calculated using the static loading scenario. This was done by simulating four Performance Based Standards (PBS) vehicles and four conventional baseline vehicles. A representative road profile was used and the crossfall was varied from 0% to 5%. The average road wear from eight South African pavements was used to assess overall road wear impact. TruckSim® software was used to perform the heavy vehicle simulations, and the mePADS mechanistic empirical simulation software was used to perform the road wear simulations using the RMS axle loads from TruckSim®. It was found that crossfall values as low as 3% can produce a difference in road wear of more than 26.1% between the left and right sides. When comparing the road wear from a static analysis to the dynamic analyses, it was found that there is a substantial difference in the calculated road wear, even at low values of 2 to 3% crossfall, with a maximum difference of 59.3% recorded at 3% crossfall. It is therefore recommended that future road wear assessments incorporate the effect of vehicle roll motion and crossfall into road wear assessments.Papers presented at the 38th International Southern African Transport Conference on "Disruptive transport technologies - is South and Southern Africa ready?" held at CSIR International Convention Centre, Pretoria, South Africa on 8th to 11th July 2019

Comparing dynamic road wear of a performance- based standards and baseline vehicle

The paved road network is a critical asset to any country and its economy. South Africa’s paved road network has an estimated value in excess of R2 trillion. This asset is threatened by a backlog in maintenance of more than R416.6 billion, estimated in 2018. Overloaded heavy vehicles can cause more than 60% of the road wear on a road network. Most road wear analysis methods use static axle loads that are assumed to be symmetrical on either side of the road. Generally, Performance-based standards (PBS) vehicles have been shown to cause less road wear per tonne of payload compared to baseline vehicles when an assessment based on static axle loads is conducted. In this study, the dynamic road wear effects and the effects of road crossfall are studied in a road wear comparison of a PBS side tipper with a baseline vehicle. The results show that the PBS side tipper vehicle produces less road wear per tonne of payload when considering the first and fourth order aggregate tyre damage criteria for 0% and 3% crossfall. The road wear saving for fourth order aggregate tyre damage criteria for the left and right side was 10% and 11.5% at 0% crossfall and 5.7% and 11.3% at 3% crossfall. The results from the aggregate fourth order tyre damage and that from the mechanistic-empirical methodology produced similar results and indicate that the aggregate tyre damage criteria could be used for assessing PBS and baseline vehicle dynamic road damage. The study supports previous research that crossfall has a substantial influence on road damage of the left and right side of a vehicle. The maximum difference in the left and right side dynamic fourth order aggregate tyre damage was 32% for the baseline vehicle and 38% for the PBS vehicle.Papers presented virtually at the 39th International Southern African Transport Conference on 05 -07 July 202

Mathematical Modeling of Furnace Drainage While Tapping Slag and Metal Through a Single Tap-Hole

Furnace tapping is a critical operation on pyrometallurgical furnaces known for unpredictable performance in many cases. A reduced order mathematical model capable of predicting tapping rates of both slag and metal is presented. The model accounts for separate liquid phases and particle bed resistance to flow. The model is compared for consistency against results from both a water-model experiment and computational fluid dynamics simulations. The model is applied to study drainage from a typical ferro-manganese furnace. The model results show that particle bed conditions in the immediate vicinity of the tap-hole strongly influence tapping rates and that the slag/metal interface deformation due to suction pressure near to the tap-hole is significant and must be accounted for in such modelspublishedVersio

Health effects of passive smoking in adolescent children

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