of single-layered structures. Because the electromagnetic parameters of the lossy material are constrained by the Kramers-Kronig relationship, the effective absorption bandwidth (EAB) of the single-layered microwave absorbers is restricted, and it is difficult to achieve ultra-broadband absorption from several GHz to several tens of GHz. [8,9] Generally, microwave absorbing materials mainly dissipate electromagnetic wave energy through dielectric loss and magnetic loss. Due to the dependence of resonance thickness, the influence of adjusting the loss ability of single-layered absorbing materials on improving the absorbing bandwidth is limited. [10,11] The absorption bandwidth of the absorber can be effectively widened through structural design such as circuit-analog laminate, 2D frequency selective surface, and 3D metasurface. [12][13][14][15] Among them, the 3D metasurface absorbers which feature a periodic array of sub-wavelength structures have been proven to advantage in achieving broadband absorption at a thin thickness. [16][17][18] The complex geometry of the 3D spatial structure can generate multiple resonance absorption peaks in different frequency bands, and meanwhile distort the electromagnetic field nearby its surface and cause strong resonance and diffraction effects, thereby enhancing the dissipation of electromagnetic waves. [19,20] It should be noted that in order to cover the lowfrequency range, magnetic components are usually introduced into the composites to adjust the wave impedance and increase the loss ability. [21,22] The absolute dielectric loss material without the addition of magnetic components is considered difficult to achieve ultra-broadband absorption at a low thickness.In our previous study, it was found that the broadband absorption of X-band and Ku-band can be achieved by converting the 2D microwave absorbing material Ti 3 C 2 T x MXene nanosheets into a 1D microrod structure. [23,24] Herein, through the multi-scale design from the microscopic composite structure to the macroscopic 3D metasurface, a thin-thickness microwave metamaterial absorber (MMA) based on pure dielectric loss substance composed of hollow carbon/MXene/Mo 2 C (HCMM) microtube is proposed. As shown in Figure 1, the specific design route mainly contains three steps: first, by employing polyethylene terephthalate (PET) non-woven fabric as the substrate, the hierarchical HCMM microtube with a micron-scale cavity is fabricated via a self-assembly method and subsequent heat Developing various nanocomposite microwave absorbers is a crucial means to address the issue of electromagnetic pollution, but remains a challenge in satisfying broadband absorption at low thickness with dielectric loss materials. Herein, an ultra-broadband microwave metamaterial absorber (MMA) based on hollow carbon/MXene/Mo 2 C (HCMM) is fabricated by a multiscale design strategy. The microscopic 1D hierarchical microtube structure of HCMM contributes to break through the limit of thickness, exhibiting a strong reflection loss of -66.30 dB (99....

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Morphometrics is a quantitative analysis to compare a set of geometric representations of forms, including shape and size. Analysis of shape variation is useful in systematics, evolutionary biology, biostratigraphy, and developmental biology. Distinguished by the data being analyzed, three forms of morphometrics are commonly recognized. Traditional morphometrics measures the lengths, ratios, angles, etc., of patterns of shape variations. Outline-based morphometrics analyzes the outlines of forms using open or closed curves. Landmark-based geometric morphometrics summarizes shapes in terms of the coordinates of anatomical landmarks. The three morphometric methods are able to capture the variation of forms exactly, but require analyzing numerous variables. As an alternative approach to morphometrics, this paper presents a kinematic synthesis methodology of planar rigid-body chains. This methodology approximates the set of profile curves that represent a series of shapes with a single chain comprised of rigid-body links connected by revolute or prismatic joints. The primary advantage of the presented approach is that a modest number of physical parameters describes the shape and size change between a set of curves. Three morphometric problems are investigated by applying the methodology of synthesizing planar rigid-body chains to match the prescribed shapes. The result validates that the presented methodology might be used as an alternative approach to the analysis of morphological forms.

This paper presents a kinematic synthesis methodology for planar shape-changing rigid-body mechanisms that addresses constraints arising in the design of variable-geometry polymer extrusion dies. Such a die is capable of morphing its orifice in order to create extrusions of non-constant cross section. A variable-geometry shape-changing die problem is defined by a set of design profiles of different shapes and arc lengths, which approximate various cross sections of the extrusion. The primary advantage of the presented methodology is addressing the need for bodies in the mechanism formed by fusing links in the shape-changing portion of the chain. Previous methodologies included such fused links, but only at the end of the synthesis process where revolute joints were seen to be underutilized. A new method is needed to control, or even eliminate the use of revolute joints in the shape-changing chain of rigid links. The result of this new work is an iterative method which generates an optimized morphing chain to best match the design profiles while minimizing the number of prismatic and revolute joints needed to do so. The additional variable-geometry design constraints also require a generalization to the definition of fixed-end profiles previously proposed, also allowing chain ends to be defined by prismatic joints on a fixed line of slide. A virtual-chain method is also proposed to solve closure problems caused by the reduction in the number of revolute joints.