Yan Luximon

A comparison between Chinese and Caucasian head shapes

Univariate anthropometric data have long documented a difference in head shape proportion between Chinese and Caucasian populations. This difference has made it impossible to create eyewear, helmets and facemasks that fit both groups well. However, it has been unknown to what extend and precisely how the two populations differ from each other in form. In this study, we applied geometric morphometrics to dense surface data to quantify and characterize the shape differences using a large data set from two recent 3D anthropometric surveys, one in North America and Europe, and one in China. The comparison showed the significant variations between head shapes of the two groups and results demonstrated that Chinese heads were rounder than Caucasian counterparts, with a flatter back and forehead. The quantitative measurements and analyses of these shape differences may be applied in many fields, including anthropometrics, product design, cranial surgery and cranial therapy.

The 3D Chinese head and face modeling

Perfect fit for people has always been a target for product design. Designers commonly use traditional anthropometric dimensions for 3D product design thus creating a lot of fitting problems when dealing with the complexities of human body shapes. The development of recent 3D anthropometric survey has created an opportunity for complex shape analysis on human model by collecting 3D scan data. Using 3D point cloud data from the SizeChina survey, a methodology of creating a homologous 3D head and face model was demonstrated in this study. Anatomical and virtual landmarks, and surface modeling algorithm based on point cloud data were applied in building the model. The head and face models for all scans had the same amount of vertices with consistent features. The average Chinese models showed obvious differences between male and female. The variations of head and face shapes were analyzed using Principal Component Analysis and the results showed that the largest variations among people were general size, especially for width and depth. However face height, forehead, back of the head, chin and jaw area were also important when describing the 3D shape. The results from this study may be useful in the design of head and facial products.

Shoe-last design innovation for better shoe fitting

Shoe-last, a 3D mould used for making footwear, influence the shape, size and fitting of footwear. Current shoe-last design software has focused mainly on reverse engineering of existing shoe-last and modification. Shoe-last designers have generally preferred to design the shoe-last manually due to limitations of design software. In order to solve these problems, a new software based on CATIA platform was developed. The shoe-last model is based on foot shape measurement data and foot biomechanics. Using the existing shoe-last design standards and the sections from existing shoe-lasts, design tables and relationship equations enables the design of shoe-last with different toe type, heel height and custom shoe-last. The design includes comfort and fit aspects as well as design aspect, therefore enables design of aesthetical comfortable shoes. Since the design can be modified instantaneously, the designers could visualize design changes leading to a reduction in shoe-last design cycle.

The relationship between monochronicity, polychronicity and individual characteristics

With the increasing complexity of control rooms and the information explosion, effective multitasking is now desired. Monochronicity and polychronicity, which describe a persons ability to do one thing and many things at a time, respectively, have been studied for a long time. However, it is not clear these abilities are related to various individual characteristics. Forty-eight Chinese participants were tested on their perception, memory, judgement, attention ability and cognitive style. They also performed a task that required search and calculation under three conditions of unpaced, paced and paced with sequencing. There were significant differences in the performance and strategy between monochronic and polychronic individuals in the selective attention test. Monochronic individuals focused their attention on the primary task and achieved higher performance. Polychronic individuals had somewhat better total performance in more than one task under time-constrained conditions. The results clearly indicate that an individuals time use behaviours ought to be considered in training and control scenarios to account for differences among people.

Sizing and grading for wearable products

Sizing and grading are widely used to create products to fit selected populations. Currently, the sizing and grading rules are derived from anthropometric measures; however past researches have indicated that it is not very accurate. This study proposes a new technique to use principal component analysis (PCA) on 3D surface points for sizing and grading wearable products. The accuracy of the proposed method is illustrated by developing a sizing and grading rule for the feet. After developing a model using the feet data of 60 participants and validating using the feet data of 10 different participants, results showed that sizing and grading using PCA is more accurate than traditional techniques. Compared with traditional foot sizing, PCA based sizing and grading showed an improvement of about 25% in accuracy. In addition, results also indicated that the grading rule derived from PCA loading was better than the proportional grading. This research provides a new direction to consider when developing the sizing and grading rules. It can be extended to calculate the number of sizes and the size increment for various wearable products.

Effects of heel base size, walking speed, and slope angle on center of pressure trajectory and plantar pressure when wearing high-heeled shoes

High-heeled shoes are associated with instability and a high risk of fall, fracture, and ankle sprain. This study investigated the effects of heel base size (HBS) on walking stability under different walking speeds and slope angles. The trajectory of the center of pressure (COP), maximal peak pressure, pressure time integral, contact area, and perceived stability were analyzed. The results revealed that a small HBS increased the COP deviations, shifting the COP more medially at the beginning of the gait cycle. The slope angle mainly affected the COP in the anteroposterior direction. An increased slope angle shifted the COP posterior and caused greater pressure and a larger contact area in the midfoot and rearfoot regions, which can provide more support. Subjective measures on perceived stability were consistent with objective measures. The results suggested that high-heeled shoes with a small HBS did not provide stable plantar support, particularly on a small slope angle. The changes in the COP and pressure pattern caused by a small HBS might increase joint torque and muscle activity and induce lower limb problems.

Review on 3D Scanners for Head and Face Modeling

There is a need of accurate anthropometric data of human head and face for both research and product designing. In past conventional measurements techniques were used to acquire anthropometric measurements for designing of products using scales, calipers, tapes which were less accurate and reliable, but with the advent of 3D scanner it has become very convenient for the researchers to acquire accurate 3D anthropometric head and face measurement. In the last three decades there has been a constant effort in optimizing the 3D scanners for improving its accurate and making it more user-friendly. This study discusses three different types of 3D scanners used for scanning head and face and tries to analyze their performance. The scanners included in the study are: Cyberware 3030 color scanner, Artec Eva 3D scanner and Structure sensor ST01 mode. The study provides an overview of possible advantages and limitations of all the three scanners.

Older Adults and Digital Technology: A Study of User Perception and Usage Behavior

Nowadays, with aging society, there are an increasing number of older adults, who are current or potential users of digital technologies. However, how older adults perceive and use digital technologies does not receive sufficient research attentions. This study investigated older adults’ user perception and usage behavior of digital technologies in Hong Kong. A semi-structured interview was designed to understand their feelings and experience of daily digital technology use. The results found that older adults presented positive attitudes to the digital technology use but less self-efficacy of their own capabilities of learning these technologies. The majority of participants reported difficulties when using and learning digital technologies, especially navigation problems. Additionally, there is a tendency of using mobile computing devices instead of computers among older adults. By considering older adults’ special needs and limitations in future digital technology design, a better user experience could be assured.

A design and evaluation tool using 3D head templates

AbstractProduct fit greatly depends on the human anthropometric information. Traditional anthropometric dimensions do not describe the 3D shape of the human body that is required by product designers, especially for head fitting products. With the development of CAD software and 3D scanning technology, 3D human modeling is becoming more important in design area. Based on SizeChina database, a 3D digital design and evaluation tool that allow designers to easily access Chinese head and face shape data in the Solidworks CAD environment has been developed in this study. The various sizes of 3D head templates are generated in using reference dimensions. This digital design tool can be used to visualize, evaluate and correct product fit on screen during the development process. This method allows the creation of better fitting products for the head and face.

Time use behavior in single and time-sharing tasks

Human errors in aviation, process plants and other critical industries can result in dire consequences and hence it is essential to understand the operator behavior and task characteristics in order to improve task performance and safety. The time available and how it is used by the operator are important factors in multi-task situations. Polychrons are people, who favor doing multiple tasks at the same time, while monochrons prefer doing tasks in series. In this study, the strategy, performance and workload of monochrons and polychrons were evaluated in a single and dual control tasks. The task difficulty and multiple task priority were independent variables. Results indicated that polychrons switched between two tasks more than monochrons and achieved better performance when the tasks were equally important and difficult. When the priority between the tasks was different, monochrons changed their emphasis to the more important task even though polychrons did not change their strategy as dramatically as the monochrons. In addition, monochrons indicated significantly higher workload and difficulty than polychrons. Results of this study can be important for the development of training programs of personnel involved in time-critical operations.