Kim Blackburn

Influence of footwear and soil density on loading within the shoe and soil surface during running.

Using pressure transducers in soil surfaces prepared in controlled conditions, the vertical stress was recorded at 100 mm, 200 mm, and 350 mm depth within two soil surfaces of 1460 kg/m3 and 1590 kg/m3 for five subjects of 747–843 N body weight running at 4 m/s (5 per cent). Simultaneous in-shoe pressure data were collected to investigate the influence of soil density on loading experienced by the player and to provide information on the load applied to the surface. For each soil density, the subjects wore three different footwear types: soccer boots with traditional studs, boots with moulded studs, and boots designed for synthetic turf. For the mean of all subjects, there was no significant difference in the maximum vertical soil stress or loading rate between surfaces at any depth but within each surface there was a significant reduction of 32 kPa between –100 mm and the other depths. The peak loading rate was two orders of magnitude greater at –100 mm than at –200 mm or –350 mm. The variation in maximum vertical stress at –100 mm for different subjects was significant (p<0.001) and increased with increasing subject weight (R2 = 0.87); at –200 mm and –350 mm there was no significant subject or density effect; a similar pattern was observed with the peak loading rate, with a linear relationship between the loading rate and the subject weight. In-shoe pressure data revealed no significant differences in the peak force or loading rate between surfaces, but a significantly lower heel pressure for the soft (1460 kg/m3) surface compared with the hard (1590 kg/m3) surface (p<0.05). Wearing of different footwear had no influence on the peak force or pressure but revealed a lower rate of loading of force for the moulded boot than for the studded boot when performing on the hard surface. There was a low and non-significant relationship between the peak input force and the peak force experienced within the surface (R2 = 0.01; p > 0.05), however, peak resultant pressure data were used successfully to model the vertical stress distribution during running using a linear elastic model of soil behaviour. This novel approach to understanding the behaviour of the soil surface and the player has revealed a complex relationship between the input load and the load experienced by the surface. Future models will seek to understand this relationship further.

Modelling and Validation of Synthesis of Poly Lactic Acid Using an Alternative Energy Source through a Continuous Reactive Extrusion Process

PLA is one of the most promising bio-compostable and bio-degradable thermoplastic polymers made from renewable sources. PLA is generally produced by ring opening polymerization (ROP) of lactide using the metallic/bimetallic catalyst (Sn, Zn, and Al) or other organic catalysts in a suitable solvent. In this work, reactive extrusion experiments using stannous octoate Sn(Oct)2 and tri-phenyl phosphine (PPh)3 were considered to perform ROP of lactide. Ultrasound energy source was used for activating and/or boosting the polymerization as an alternative energy (AE) source. Ludovic® software, designed for simulation of the extrusion process, had to be modified in order to simulate the reactive extrusion of lactide and for the application of an AE source in an extruder. A mathematical model for the ROP of lactide reaction was developed to estimate the kinetics of the polymerization process. The isothermal curves generated through this model were then used by Ludovic software to simulate the “reactive” extrusion process of ROP of lactide. Results from the experiments and simulations were compared to validate the simulation methodology. It was observed that the application of an AE source boosts the polymerization of lactide monomers. However, it was also observed that the predicted residence time was shorter than the experimental one. There is potentially a case for reducing the residence time distribution (RTD) in Ludovic® due to the ‘liquid’ monomer flow in the extruder. Although this change in parameters resulted in validation of the simulation, it was concluded that further research is needed to validate this assumption.

A Technical and Economic Feasibility Study of Green Decortication of Hemp Fibre for Textile Uses

Abstract In 2003-4 BioRegional Development Group carried out a technical and economic feasibility study of a method of green decortication of hemp and degumming for the production of textile fibre. The study was published in December 2004. Two field trials of the green decortication technology took place in the UK and Australia, Cranfield University evaluated the process in both instances. Some of the fibre produced was subsequently processed in preparation for spinning. This paper contains the findings of these trials.

Quantitative evaluation of stereo visual odometry for autonomous vessel localisation in inland waterway sensing applications

Autonomous survey vessels can increase the efficiency and availability of wide-area river environment surveying as a tool for environment protection and conservation. A key challenge is the accurate localisation of the vessel, where bank-side vegetation or urban settlement preclude the conventional use of line-of-sight global navigation satellite systems (GNSS). In this paper, we evaluate unaided visual odometry, via an on-board stereo camera rig attached to the survey vessel, as a novel, low-cost localisation strategy. Feature-based and appearance-based visual odometry algorithms are implemented on a six degrees of freedom platform operating under guided motion, but stochastic variation in yaw, pitch and roll. Evaluation is based on a 663 m-long trajectory (>15,000 image frames) and statistical error analysis against ground truth position from a target tracking tachymeter integrating electronic distance and angular measurements. The position error of the feature-based technique (mean of ±0.067 m) is three times smaller than that of the appearance-based algorithm. From multi-variable statistical regression, we are able to attribute this error to the depth of tracked features from the camera in the scene and variations in platform yaw. Our findings inform effective strategies to enhance stereo visual localisation for the specific application of river monitoring.

Nanomaterials Life Cycle Analysis : Health and Safety Practices , Standards and Regulations - Past , Present and Future Perspective

A new technology always raises new issues with its introduction on the market. Nanotechnology is not an exception. The advantages of nanomaterials use are not to demonstrate anymore and so, the commercializati on of consumer products based on nanotechnology doesn’t stop increasing. The introduction on the market of nanoproducts also involves some uncertainties. Risks regarding the environment and human health are not well known by the scientist, and the legislat ion doesn’t cover health and safety aspects related to nanomaterials. Especially, fate of nanoparticles during the life - cycle of nanoproducts is not fully experienced due the large variety of nanomaterials existing and their diverse applications. It is saf e to say that, given the explosive R&D and commercial uptake of nanomaterials unsurprisingly, the regulations governing the use and disposal of nanomaterials during its life cycle is behind the curve. The wide acceptance of nanotechnology by the consumers depends on

Techniques for estimating contact pressure resulting from loaded agricultural tyres

Recent increases in the weight of agricultural machines can cause soil management problems in the form of soil compaction. Tyre contact pressure is often used as an indicator of the potential for a machine to cause compaction.

The Measurement of Applied Pressure at Depth with Two Natural Soil Surfaces at Different Densities

To advance the engineering of natural turf sports surfaces it is necessary to characterize the stress states and paths of the loads applied by athletes during activity. Such loads are transitory and dynamic. In order to characterize the pressure distribution in a natural soil sports(?) surface a novel experiment was conducted in the 20 m long, 1.8 m wide, 1.0 m deep soil dynamics laboratory at Cranfield University. Two soil surfaces of 1460 kg m−3 and 1590 kg m−3 were constructed from a sandy loam soil (66% sand, 17% silt and 17% clay). Hardness (0.5 kg Clegg impact hammer) was 125 and 235 g, and maximum penetration resistance 1200 and 1800 kPa, respectively. Seven subjects (57–85 kg body mass) were asked to run at a constant speed of 4 m s−1 (±5%) over each surface, three times, in three different types of footwear used in soccer. Loading and unloading of the soil surface was measured using a ceramic membrane pressure transducer of 19 mm diameter, aligned to the vertical and buried at 100, 200 and 350 mm below the surface. Pressure data were recorded at 5 kHz and processed to determine peak pressure and loading and unloading behaviour of the soil surface. ANOVA determined maximum pressure for the two surfaces was significantly lower at 350 mm (7–15 kPa) and 200 mm (2–3 kPa) than at 100 mm (52–61 kPa) depth (p=0.05) but that there was no significant difference between the two surfaces at any particular depth. Maximum pressure at 100 mm depth was linearly correlated with subject weight (for Subjects 3–7). Loading and unloading behaviour of the soil showed a pattern of bimodality, caused by heel strike and push-off, similar to biomechanics running experiments conducted with force plates. These results suggest that in soil surfaces, pressure distribution at and below 200 mm is independent of surface density or subject, but that mechanical properties such as density and stiffness must be considered in the top 100 mm of a surface. This research also demonstrates the applicability of in-surface pressure transducers in integrated soil mechanics and biomechanics testing.

Off-Road Dynamics Research at Cranfield University at Silsoe

This paper describes the laboratory and equipment designed and developed by the staff of Cranfield University at Silsoe to provide a centre to undertake research into the terramechanics of off road vehicles and single tyres and tracks; and the soil-machine dynamics of tillage and earthmoving equipment for civil and defence purposes. The laboratory comprises of a 45 m long, 5 m wide soil lane that has the facility to control soil moisture and water table levels together with single wheel test apparatus for both dynamic and quasi-static tyre performance studies, a “smart” winch to provide a dynamically controlled pull for “slip-pull” performance studies of whole vehicles, a tyre and track test device for compaction studies and a whole vehicle articulation rig. The facility has been designed to meet the needs of a range of applications including agriculture, automotive, construction, military, motor sport and telecommunications for the provision of previously unavailable tire, vehicle and machine performance data.

Development of CNC prototype for the characterization of the nanoparticle release during physical manipulation of nanocomposites

ABSTRACT This work focuses on the release of nanoparticles from commercially used nanocomposites during machining operations. A reliable and repeatable method was developed to assess the intentionally exposure to nanoparticles, in particular during drilling. This article presents the description and validation of results obtained from a new prototype used for the measurement and monitoring of nanoparticles in a controlled environment. This methodology was compared with the methodologies applied in other studies. Also, some preliminary experiments on drilling nanocomposites are included. Size, shape and chemical composition of the released nanoparticles were investigated in order to understand their hazard potential. No significant differences were found in the amount of nanoparticles released between samples with and without nanoadditives. Also, no chemical alteration was observed between the dust generated and the bulk material. Finally, further developments of the prototype are proposed.

Chronological review of the catalytic progress of polylactic acid formation through ring opening polymerization

The disposal of a large amount of polymer waste is one of the major challenges of this century. Use of bio-degradable polymers obtained from sustainable sources presents a solution to this problem. Poly lactic acid (PLA), a bio-degradable polymer, can be synthesized from sustainable sources as corn, starch, sugarcane and chips. Ring opening polymerization (ROP) of Lactide (LA) monomer using metal/bimetallic catalyst (Sn, Zn or Al) is the preferred method for synthesis of PLA. However, the PLA synthesized using such catalysts may contain trace elements of the catalyst. These catalyst traces are known carcinogens and as such should be (ideally) eliminated from the process. Use of the organic catalyst instead of metallic catalysts, may be one of the prominent solutions.