No abstract

The auricular conchae of 310 young Chinese people (169 men and 141 women) aged 18–28 years were classified into different groups and differentiated in terms of shape as a basis to designing wearable and non‐slip earphones. Seven characteristic distances could be obtained accurately by defining 5 characteristic points and extracting their 3‐dimensional (3D) coordinates from 3D digital models (obtained by scanning 310 ear impressions) automatically. The shape differences of auricular conchae were statistically analyzed. Results show that the average dimensions of auricular conchae for men are generally larger than those for women, and the shapes of auricular conchae significantly differ among the participants. The shapes of auricular concha were classified into 24 groups, depending on the characteristic distances. For each group, the coordinates of 5 common‐characteristic points were determined and the basic shape was summarized. The percentage of the samples in each group was statistically given, and 8 prioritized groups of samples more than 5% were suggested. Finally, the feasibility of the classification method was demonstrated by designing earphone, 3D printing, and wearing verification.

Simultaneous wireless information and power transfer (SWIPT) is a promising technique to prolong the lifetime of energy-constrained relay systems. Most previous works optimize power-splitting (PS) scheme based on a linear or a simple two-piecewise linear energy harvesting (EH) model, while the employed EH model may not characterize the properties of practical EH harvesters well. This leads to a mismatch between the existing PS scheme and the practical EH harvester available for relay systems. Motivated by this, this paper is devoted to the design of PS scheme in a nonlinear EH amplify-and-forward energy-constrained relay system in the presence of a direct link between the source and the destination. In particular, we formulate an optimization problem to maximize the system capacity according to the instantaneous channel state information, subject to a nonlinear EH model based on the logistic function. The objective function of the formulated problem is proven to be unimodal and there is no closed-form expression for the optimal PS ratio due to the complexity of logistic function. In order to reduce overhead cost of optimizing PS ratio, a simpler nonlinear EH model based on the inverse proportional function is employed to replace the nonlinear EH model based on the logistic function and we further derive the closed-form expression for the optimal PS ratio. Simulation results reveal that a higher system capacity can be achieved when the PS scheme is optimized based on nonlinear EH models instead of the linear EH model, and that there is only a marginal difference between the capacity under the two optimal PS schemes optimized for two different nonlinear EH models.

This study led to the development of a parametric design method for mass-customised head/face products. A systematic review of different approaches for mass customization was conducted, identifying advantages and limitations for their application to new product development. A parametric modelling algorithm of a 3D human face was developed using selected scanned 3D head models. The algorithm was developed from a set of measurable and adjustable parameter points related to the facial geometry. These parameters were defined using planimetry. Using the assigned parameter values as input, the parametric model generated 3D models of a human face that served as a reference for the design of customized eyewear. The current challenges and opportunities of mass customized head/face products are described, along with the possibilities for new parametric product design approaches to enable rapid manufacturing and mass customization. This study also explored whether a new parametric design framework for mass customization could be effectively implemented as an early-stage new product development strategy for head/face products.

This paper focuses on the dynamic responses of a planar mechanism with multiple clearance joints. The effect of the impact between the journal and the bearing in the clearance joint is described using an improved impact force model, and a typical four-bar linkage mechanism with multiple clearance joints is presented as an example. Two conditions are considered in this research, one is the single clearance joint with different position, and the other is multiple clearance joints. From a large number of numerical results, some important conclusions are obtained as follows: (1) with the influence of the clearance joint, the dynamic output of system has obvious vibration in comparison to the ideal value. (2) The position of the clearance joint has a clear effect on the response of system; the larger the distance of the clearance joint from the drive motor, the smaller its influence on the output of the system. (3) With the increase in the clearance joint number, the dynamic stability of the multibody system is decreased gradually, and the dynamic characteristic of the system also appears as obvious nonlinear phenomenon. (4) The coupling phenomenon appears when multiple clearance joints in the multibody system are considered, which should be examined seriously during the process of design and numerical analysis.