Improving fit of bicycle helmet liners using 3D anthropometric data

3D anthropometry has provided much-needed information about the size and shape of the head, which can be used to improve the fit of protective helmets. In this study, a new 3D head scan sizing method was implemented in a reverse engineering approach for bicycle helmet liner dimensioning. The inside liner of a commercially available helmet was modified to improve the fit for a selected size group of 30 participants. The fit of the standard and new liner were assessed and compared, using the Helmet Fit Index (HFI). The HFI scores showed a significant improvement of overall fit (Difference: 11.32 ± 7.82 (μ ± SD), p < 0.0005) and for each of five defined regions of the liner inside surface. The presented methodology for dimensioning helmet liners based on 3D anthropometry proved effective, resulting in improved fit for the end users

3D digital headform models of Australian cyclists

Traditional 1D anthropometric data have been the primary source of information used by ergonomists for the dimensioning of head and facial gear. Although these data are simple to use and understand, they only provide univariate measures of key dimensions. 3D anthropometric data, however, describe the complete shape characteristics of the head surface, but are complicated to interpret due to the abundance of information they contain. Consequently, current headform standards based on 1D measurements may not adequately represent the actual head shape variations of the intended user groups. The purpose of this study was to introduce a set of new digital headform models representative of the adult cyclists' community in Australia. Four models were generated based on an Australian 3D anthropometric database of head shapes and a modified hierarchical clustering algorithm. Considerable shape differences were identified between our models and the current headforms from the Australian standard. We conclude that the design of head and facial gear based on current standards might not be favorable for optimal fitting results

Finite Element Bicycle Helmet Models Development

AbstractImpact attenuation performance of three different range of commercial bicycle helmet were investigated in lateral drop impact test in accordance to AS/NZS 2063:2008, Australian/New Zealand Standard for bicycle helmet using numerical simulation and and experimental impact test. The aim of this research is to develop a simulation model of drop impact test, which to be used in further investigations of user-centred design approach of bicycle helmet. Three commercial bicycle helmet models were used in this study. All helmets and J headform were scanned using Flexscan 3D scanning equipment. Post-scan processing jobs of scanned geometry models such as helmet liner, shell and headform were conducted in Geomagic Studio 12. The experimental impact test is carried out using 2-wire drop test facility in accordance to the AS/NZS 2063:2008, Australian Standard for bicycle helmet. A few samples were cut from the liner of each helmet to determine the density of Expanded Polystyrene (EPS). Headform peak linear acceleration, impact duration and impact speed of each helmet were measured and recorded from the drop test. The scanned geometry models were imported into Abaqus. A drop impact simulation was developed based on the density and impact speed data obtained from the physical test. Inner liner of bicycle helmet, made from Expanded Polystyrene (EPS), was modeled using crushable foam properties, while headform and anvil were modeled as rigid bodies. Peak linear accelerations and impact duration of the headform on each helmet at three different impact locations of helmet were recorded. A robust correlation study using peak linear acceleration score, impact duration score and Pearson correlation coefficient between the data from physical test and numerical model was conducted. Good correlation scores (>80%) were achieved between the numerical model and experimental impact test in terms of headform peak linear acceleration and impact duration score, suggesting that the simulation model is in good correlation with those from physical test

The influence of physical properties on comfort performance of bedsheet fabrics

This paper analyzes the comfort performance of different types of bedsheet fabrics which are polyester, polyester blended with Tencel, cotton, Tencel and modal. The objectives of this study are to determine the physical and comfort properties of bedsheet fabrics as well as to evaluate the influence of physical properties on the comfort performance of bedsheet fabrics. The preparation of samples involved sourcing the fabrics that are commercially used. Physical properties such as thickness, mass per unit area and porosity were determined in order to evaluate their relationship on comfort properties such as thermal resistance, wicking area and water vapour transmission rate (WVTR). It was found that Tencel fabric exhibited the lowest thermal resistance of 0.0037 m2 °C/W while polyester fabric showed the highest thermal resistance of 0.0084 m2 °C/W. For wicking area, polyester blended with Tencel fabric demonstrated the highest wicking area whereas Tencel fabric displayed the highest WVTR of 1069.21 g/24h.m2 . Based on findings, Tencel bedsheet could offer better comfort in hot environment as the heat and water vapour can pass through the fabric easily compared to other fabrics. Meanwhile, polyester bedsheet will offer better comfort in cold environment as it can retain the heat and this can help the users to feel warmer in cold environment

Urban Trees Diversity in Kuching North City and UNIMAS, Kota Samarahan, Sarawak

Tree species composition often varies widely amongst cities, depending to their geographical locations, urban history, land area or population. The objective of the study was to identify the species diversity of urban trees planted along the roadsides of Kuching North city and Universiti Malaysia Sarawak (UNIMAS), Kota Samarahan. A total of 31,181 trees representing 186 species were sampled. The roadside trees of Kuching North city were more diverse with 176 species of trees while 28 species were recorded from UNIMAS. Inverse of Simpson Index of diversity of the roadside trees in Kuching North city and UNIMAS was 21.0 and 10.7, respectively. In particular, five common species dominated the whole study area with indigenous species dominating UNIMAS, while exotic species exceed indigenous species at roadsides in Kuching North city. Five popular species accounted for one third of the total trees planted with Mimusops elengi as the dominant species planted at both sites. All the species recorded from both the study areas were less than 10% and they complied with the urban forest health status guideline, whereby a diverse tree population might slow or prevent the spread of insects or diseases, and in the event that such pests should become established, the impact on a diverse tree population may be less severe. Data on species floristic composition will assist the local authorities in the planting, maintaining and planning for future replanting activities

Decision making process in keystroke dynamics

Computer system intrusion often happens nowadays. Various methods have been introduced to reduce and prevent these intrusions, however no method was 100% proven to be effective. Therefore, to improve the computer’s security, this writing will explain the application of KD in the application system. The effectiveness of KD could not guarantee one hundred percent to prevent the computer intrusion, but it can be used as a second level of security after the login page in the application system. The pattern and time taken while typing by an individual is the core for the second level of security check after the login page. This writing will elaborate and conclude past studies related to KD on the aspects of decisionmaking process. Various methods of processing KD data that have been used are listed and the results of the study are compared. The results of this writing are expected to help new researchers in the process of evaluating KD data

Fit, stability and comfort assessment of custom-fitted bicycle helmet inner liner designs, based on 3D anthropometric data

Research has demonstrated that a better-fitted bicycle helmet offers improved protection to the rider during an impact. Nowadays, bicycle helmets in the market that range in size from small/medium to medium/large might not fit the diverse range of human head shapes and dimensions. 3D scanning was used to create 3D head shape databases of 20 participants who volunteered for the study. We developed new custom-fitted helmet inner liners, based on the 3D head shape of two sub-groups of participants, to map their head sizes and contours closely to the conventional Medium (M) and Large (L) sizes as described in from AS/NZS 2512.1: 2009. The new custom-fitted helmet was compared with the helmet available in the market place in a dynamics stability test and from participants' subjective feedback. A significant reduction in the angle of helmet rotation on the headform in the lateral direction was recorded for the custom-fitted helmet. A Wilcoxon signed-rank test was conducted to evaluate participants’ feedback on the helmets according to different area definitions. The overall fit and comfort and the top region of the new helmet were significantly improved. However, no difference was found at the significant level of 0.05 for the front and rear region of the new helmet

Development of a Survey Instrument for Measuring Firefighter Ergonomic Factors in Hose Rolling Activity A Pilot Study

The hose is an essential piece of equipment for firefighters on the job. Flaking, roll and coil, dutch roll, and figure eight are all methods of rolling the hose. Hose rolling requires a combination of uncomfortable postures, repetitive motions, and forceful exertion, which can be stressful on firefighters' bodies. Several firefighters' work duties include the application of high physical loads to the human body. High force demands require muscles to work harder, increasing tiredness and the risk of Musculoskeletal Disorders (MSDs). The main objective of this paper is to present the development and validation of a survey instrument for measuring firefighter ergonomic factors in rolling activity for a pilot study. A set of survey instruments was developed, which consisted of four sections: the demographic profile of the respondent, the Cornell musculoskeletal discomfort survey (CMDQ), hose rolling activity among firefighters, and the design criteria for ergonomic hose rollers. The survey instruments's content was obtained from extensive literature research and expert input. A pilot study was conducted at Pagoh Fire Station. The reliability and validity of the instrument were determined through Cronbach’s alpha, face validity, and content validity. Cronbach’s alpha values for each section of the survey instruments range from 0.741 to 0.928, while the value for Cronbach’s alpha for all 26 standardized items is 0.854. Finally, the findings suggested that this instrument had appropriate reliability and validity to accomplish its aims. The survey instrument is now complete and ready for the distribution of larger amounts of data

Design of hose roller for firefighter: a fatigue study

In a working environment, worker’s safety and health are the most critical considerations. Previous study discovered that firefighters are exposed to a great deal of ergonomic risk factors (ERF). ERF exposure during hose rolling includes awkward posture and forceful exertion. Therefore, the primary goal of this research paper is to fabricate an ergonomic hose roller for firefighters and conduct a fatigue analysis to determine the efficiency of the tool designed to safeguard firefighters against the risk of low back disorder (LBD). Hose roller testing is necessary to guarantee that it can withstand the weight of fire hoses while still being comfortable for users’ bodies. Fatigue analysis was conducted using Industrial Lumbar Motion Monitor (i-LMM) equipment to evaluate LBD risk during hose rolling. Manual handling contributes 57.67% to the total average percentage value used to compute LBD risk results, while utilizing a roller tool, the hose rolling procedure yields a 27% LBD risk limit value. The design of experiment (DOE) method should be used in future studies to gather more information for the LBD risk assessmen