Experimental study of load-bearing cold-formed steel walls exposed to realistic design fires

This paper presents the details of full scale fire tests of LSF wall panels conducted using realistic fire time-temperature curves. Tests included eight LSF wall specimens of various configurations exposed to both parametric design and natural fire curves. Details of the fire test set-up, test procedure and the results including the measured time-temperature and deformation curves of LSF wall panels are presented along with wall stud failure modes and times. This paper also compares the structural and thermal behavioural characteristics of LSF wall studs with those based on the standard time-temperature curve. Finally, the stud failure times and temperatures are summarized for both standard and realistic design fire curves. This study provides the necessary test data to validate the numerical models of LSF wall panels and to undertake a detailed study into the structural and thermal performance of LSF wall panels exposed to realistic design fire curves.

Repeatability of static load bearing exercises during rehabilitation of individuals with transfemoral amputation fitted with osseointegrated implant

Bone-anchored prostheses, relying on implants to attach the prosthesis directly to the residual skeleton, are the ultimate resort for patients with transfemoral amputations (TFA) experiencing severe socket discomfort. The first patient receiving a bone-anchored prosthesis underwent the surgery in 1990 in the Sahlgrenska University Hospital (Sweden). To date, there are two commercially available implants: OPRA (Integrum, Sweden) and ILP (Orthodynamics, Germany). The key to success to this technique is a firm bone-implant bonding, depending on increasing mechanical stress applied daily during load bearing exercises (LBE). The loading data could be analysed through different biomechanical variables. The intra-tester reliability of these exercises will be presented here. Moreover the effect of increase of loading, axes of application of the load and body weight as well as the difference between force and moment variables will be discussed.

Explicit finite element modelling of bridge girder bearing pedestals

Bridge girder bearings rest on pedestals to transfer the loading safely to the pier headstock. In spite of the existence of industry guidelines, due to construction complexities, such guidelines are often overlooked. Further, there is paucity of research on the performance of pedestals, although their failure could cause exorbitant maintenance costs. Although reinforced concrete pedestals are recommended in the industry design guidelines, unreinforced concrete and/ or epoxy glue pedestals are provided due to construction issues; such pedestals fail within a very short period of service. With a view to understanding the response of pedestals subject to monotonic loading, a three-dimensional nonlinear explicit finite element micro-model of unreinforced and reinforced concrete pedestals has been developed. Contact and material nonlinearity have been accounted for in the model. It is shown that the unreinforced concrete pedestals suffer from localised edge stress singularities, the failure of which was comparable to those in the field. The reinforced concrete pedestals, on the other hand, distribute the loading without edge stress singularity, again conforming to the field experience.

Application of anomaly technique in wind turbine bearing fault detection

Bearing faults are the most common cause of wind turbine failures. Unavailability and maintenance cost of wind turbines are becoming critically important, with their fast growing in electric networks. Early fault detection can reduce outage time and costs. This paper proposes Anomaly Detection (AD) machine learning algorithms for fault diagnosis of wind turbine bearings. The application of this method on a real data set was conducted and is presented in this paper. For validation and comparison purposes, a set of baseline results are produced using the popular one-class SVM methods to examine the ability of the proposed technique in detecting incipient faults.

Histogram matching and global initialization for laser-only SLAM in large unstructured environments

This paper presents an enhanced algorithm for matching laser scan maps using histogram correlations. The histogram representation effectively summarizes a map's salient features such that pairs of maps can be matched efficiently without any prior guess as to their alignment. The histogram matching algorithm has been enhanced in order to work well in outdoor unstructured environments by using entropy metrics, weighted histograms and proper thresholding of quality metrics. Thus our large-scale scan-matching SLAM implementation has a vastly improved ability to close large loops in real-time even when odometry is not available. Our experimental results have demonstrated a successful mapping of the largest area ever mapped to date using only a single laser scanner. We also demonstrate our ability to solve the lost robot problem by localizing a robot to a previously built map without any prior initialization.

Static load bearing exercises during rehabilitation of individuals with transfemoral amputation fitted with osseointegrated implant: Load compliance

Osseointegration has been introduced in the orthopaedic surgery in the 1990’s in Gothenburg (Sweden). To date, there are two frequently used commercially available human implants: the OPRA (Integrum, Sweden) and ILP (Orthodynamics, Germany) systems. The rehabilitation program with both systems include some form of static load bearing exercises. These latter involved following a load progression that is monitored by the bathroom scale, providing only the load applied on the vertical axis. The loading data could be analysed through different biomechanical variables. For instance, the load compliance, corresponding to the difference between the load recommended (LR) and the load actually applied on the implant, will be presented here.

Description of body posture during Static load bearing exercises for individuals with transfemoral amputation fitted with bone-anchored prosthesis

The rehabilitation programs of bone-anchorage prostheses relying either on the OPRA (Integrum, Sweden) or the ILP (Orthodynamics, Germany) fixation involve some forms of static load bearing exercises (LBE). So far, most of biomechanical studies of these static LBEs focused on the direct measurements of the actual forces and moments applied on the OPRA fixation of individuals with transfemoral amputation (TFA). To date, the proof-of-concept of an apparatus to conduct these kinetic measurements has been presented, along with some preliminary data. The understanding of the kinetic data is essential to improve rehabilitation programs as well as the design of upcoming loading frames. However, kinetic information alone is difficult to interpret without concomitant kinematic data. The purpose of this preliminary study was to introduce a qualitative analysis describing the different body postures during LBE for a group of TFAs.

Load bearing exercises and functional outcome of individuals with transfemoral amputation fitted with OPRA fixation

Individuals with lower limb amputation fitted with an OPRA osseointegrated fixation are facing an extensive rehabilitation program including static load bearing exercises (LBE). The application of a suitable amount of stress stimulates osseointegration and prepares the bone to tolerate the forces and moments that will be incurred during activities of daily living (ADL. At present, the monitoring is typically carried out using a normal bathroom weighing scale. This scale provides information only on the magnitude of the vertical component of the applied force. The moment around the long axis of the fixation when the femur is perpendicular to the ground is not assessed and neither are the components of force and moment generated on the other two axes.

Static load bearing exercises during rehabilitation of individuals with transfemoral amputation fitted with osseointegrated implant: Kinetic analysis

The desire to solve problems caused by socket prostheses in transfemoral amputees and the acquired success of osseointegration in the dental application has led to the introduction of osseointegration in the orthopedic surgery. Since its first introduction in 1990 in Gothenburg Sweden the osseointegrated (OI) orthopedic fixation has proven several benefits[1]. The surgery consists of two surgical procedures followed by a lengthy rehabilitation program. The rehabilitation program after an OI implant includes a specific training period with a short training prosthesis. Since mechanical loading is considered to be one of the key factors that influence bone mass and the osseointegration of bone-anchored implants, the rehabilitation program will also need to include some form of load bearing exercises (LBE). To date there are two frequently used commercially available human implants. We can find proof in the literature that load bearing exercises are performed by patients with both types of OI implants. We refer to two articles, a first one written by Dr. Aschoff and all and published in 2010 in the Journal of Bone and Joint Surgery.[2] The second one presented by Hagberg et al in 2009 gives a very thorough description of the rehabilitation program of TFA fitted with an OPRA implant. The progression of the load however is determined individually according to the residual skeleton’s quality, pain level and body weight of the participant.[1] Patients are using a classical bathroom weighing scale to control the load on the implant during the course of their rehabilitation. The bathroom scale is an affordable and easy-to-use device but it has some important shortcomings. The scale provides instantaneous feedback to the patient only on the magnitude of the vertical component of the applied force. The forces and moments applied along and around the three axes of the implant are unknown. Although there are different ways to assess the load on the implant for instance through inverse dynamics in a motion analysis laboratory [3-6] this assessment is challenging. A recent proof- of-concept study by Frossard et al (2009) showed that the shortcomings of the weighing scale can be overcome by a portable kinetic system based on a commercial transducer[7].

Static load bearing exercises of individuals with transfemoral amputation fitted with an osseointegrated implant: Reliability of kinetic data

This study aimed at presenting the intra-tester reliability of the static load bearing exercises (LBEs) performed by individuals with transfemoral amputation (TFA) fitted with an osseointegrated implant to stimulate the bone remodelling process. There is a need for a better understanding of the implementation of these exercises particularly the reliability. The intra-tester reliability is discussed with a particular emphasis on inter-load prescribed, inter-axis and inter-component reliabilities as well as the effect of body weight normalisation. Eleven unilateral TFAs fitted with an OPRA implant performed five trials in four loading conditions. The forces and moments on the three axes of the implant were measured directly with an instrumented pylon including a six-channel transducer. Reliability of loading variables was assessed using intraclass correlation coefficients (ICCs) and percentage standard error of measurement values (%SEMs). The ICCs of all variables were above 0.9 and the %SEM values ranged between 0 and 87%. This study showed a high between-participants’ variance highlighting the lack of loading consistency typical of symptomatic population as well as a high reliability between the loading sessions indicating a plausible correct repetition of the LBE by the participants. However, these outcomes must be understood within the framework of the proposed experimental protocol.

Is the sun too bright in Queensland? An approach to robust outdoor colour beacon detection

Using cameras onboard a robot for detecting a coloured stationary target outdoors is a difficult task. Apart from the complexity of separating the target from the background scenery over different ranges, there are also the inconsistencies with direct and reflected illumination from the sun,clouds, moving and stationary objects. They can vary both the illumination on the target and its colour as perceived by the camera. In this paper, we analyse the effect of environment conditions, range to target, camera settings and image processing on the reported colours of various targets. The analysis indicates the colour space and camera configuration that provide the most consistent colour values over varying environment conditions and ranges. This information is used to develop a detection system that provides range and bearing to detected targets. The system is evaluated over various lighting conditions from bright sunlight, shadows and overcast days and demonstrates robust performance. The accuracy of the system is compared against a laser beacon detector with preliminary results indicating it to be a valuable asset for long-range coloured target detection.