Asanka S. Rodrigo

Model based foot shape classification using 2D foot outlines

This study introduces a novel technique to identify foot outline characteristics and to classify feet into groups using turning functions and clustering techniques so that shape can complement anthropometry in producing good fitting shoes. The digital 3D foot scans, obtained from 50 Hong Kong Chinese subjects (25 males and 25 females) were processed to generate the foot outlines at heights of 2 mm and 40 mm. The outlines were represented as turning functions and the similarity among shapes was determined using average linkage clustering. The results show that there are two distinct shape groups for the 40 mm foot outlines on both medial and lateral sides of the foot. The presence (46%) or absence (54%) of a medial bulge characterizes the medial side, while the two shape groups on the lateral side are mainly due to the lateral concavity in the mid-foot region. The group with a lateral concavity consists of more females (68%) and thus lateral side of foot outline appears to be gender related. Furthermore, the medial and lateral side clusters are not related to each other. The medial side shape from the 2 mm foot outline is a good indicator of fallen arches. Based on the analyses, four types of feet were identified: feet with (1) lateral concavity and a medial bulge, (2) a medial bulge and no lateral concavity, (3) lateral concavity and no medial bulge and (4) lateral concavity and a medial bulge. These shape differences can be useful in the design of shoe lasts and in the manufacture of compatible footwear so that trial and error fitting can be minimized.

Load distribution to minimise pressure-related pain on foot: a model

The optimal force distribution to minimise pain or discomfort at the foot–shoe interface is still not known. Most shoe-related products attempt to distribute the load uniformly without much consideration to the bony and soft tissue regions. An experiment was conducted to first determine the pressure pain threshold (PPT) and tissue deformation on the plantar surface of the foot. Circular probes of areas 0.5, 1.0 and 2.0 cm2 at indentation speeds of 0.5, 1 and 2 mm/s showed that PPT depends on the location stimulated, area of stimulation and the indentation speed. The results also showed that tissue stiffness is quite low for small deformations ( < 4 mm), but significantly higher at large deformations (>4 mm). The stiffness at the larger deformation region was positively correlated with PPT (r = 0.63, p < 0.001). The data were further used to develop a model with PPT, deformation and stimulated area. Practitioner Summary: Pressure at which there is an onset of pain is higher when a larger area of soft tissue is stimulated. Bony areas may be better suited to bear load on smaller areas to minimise pressure-related pain. Thus, manipulating supporting surface stiffness and surface contours can help minimise pain.

Study on impact of wind power park integration on weak power systems: A case study on Mannar wind park in Sri Lanka

Wind power is one of the largest sustainable alternative energy source used in the world for power generation. Though wind resource rich areas are available widely in Sri Lanka, excessive development of wind power plants would affect negatively on the system operations and system stability. Therefore, necessary power system analysis should be performed to determine the maximum wind penetration level into the national grid at an identified wind resource rich region. Since Mannar is identified as the prospective wind park development zone, steady state and dynamic system analysis were performed on the proposed transmission network for the year 2017 with four stages of Mannar wind development. The paper presents identified system constraints, recommended remedial actions and the final conclusion on the maximum wind penetration level from Mannar Wind Park for the year 2017.

Modelling the Power System

To study the stability and to observe how the power system behaves, during normal and abnormal conditions, availability of a simulation model of the considering Power System is very important. It is very important to ascertain that the simulation model’s performance is identical or approximately equal to the corresponding real time power system’s behavior. Since one of the aims of this research is to address frequency degradation due to Generation—Load imbalance situations in Sri Lanka, it has been decided to simulate the power system of Sri Lanka. Convenience of collecting required data from the Ceylon Electricity Board (the only utility available in Sri Lanka) on request, was an added advantage. Therefore a simulation model of the Power System of Sri Lanka (Transmission network—132 and 220 kV) was designed using the software PSCAD/EMTDC. All basic components of the transmission network such as synchronous generators, transformers, transmission lines, under-ground cables, governors, turbines etc. were simulated with their real time values.

Designing the Load Shedding Scheme

It is very important to have a clear idea about the power system we are concerning on to understand the necessity of a load shedding scheme. The parameters and their values that we use in the under frequency load shedding scheme influence in stabilizing the power system very much. The proposed load shedding scheme was designed referring to Ahsans’ scheme as a pilot model. Having identified the weaknesses with it the new load shedding schemes are proposed.

Modeling and simulation of current source converter for proposed India-Sri Lanka HVDC interconnection

The proposed 500 MW interconnection is the first DC power transmission link that is planning to connect in between Sri Lankan and Indian AC transmission networks. Proposed AC-DC system integration should determine the asymptotic stability of transmission network in both countries. Reliability can be improved by properly selecting system configurations. Properly selected DC & AC system parameters determine the stable performance at steady state and at perturbed conditions. This paper presents the modelling analysis of proposed HVDC interconnection for selected physical configurations. The interconnection was modelled using PSCAD/EMTDC software and simulated under the steady state conditions and perturbed conditions. The analytical results were verified using time domain simulations.

Designing Flight Information Displays for Quick Information Access: A Case Study of an International Airport

Increased air travel has made the provision of the optimal amount of information to travelers a necessity. Flight information is shown on electronic or mechanical display boards, but finding the required information can take some time depending on the display layout and content. This paper investigates the information configuration for quick access of flight information. Seven potential grouping methods were tested. Search time depends on the layout of information (p < 0.001). Search was fastest when the information was arranged in the order of airline logo, airline name and arrival or departure time.

A turning function based approach for foot outline classification

This study introduces a turning function based technique to classify foot outlines. Foot scans from ten males and ten females were obtained using a laser scanner. The similarities among the different foot shapes were assessed based on the Euclidean distance between turning functions. Thereafter, average linkage clustering was used to classify the differing foot outlines. Two distinct shape groups emerged for both medial and lateral sides. The presence or absence of a medial bulge results in two clusters on the medial side. Similarly, a narrow lateral side with more concavity and a wider lateral side in the midfoot region are the two clusters for the lateral side. More males (60%) showed a bulge on the medial side. The group that belongs to the narrower lateral side were predominantly females (70%). These differences in the structure of the clusters were reflected in the lack of a correlation between the medial and lateral side clusters.