Design Optimization & Analysis of a Soft Crawling Robot

Soft crawling robots (SCRs) are the kind of robots that use soft and flexible material for motion. These soft robots capable to sustain huge distortions with vast degree-of-freedom which makes them more suitable to be employed in unstructured location compared to the conventional rigid robots. Unlike soft robotics, the conventional rigid robots are capable to be employed in situations where precision is required. However, soft robots are preferable in tight spaces such as in medical surgery and earthquake search and rescue operations due to its flexibility and adaptability capability. In this research, two types of soft robots were design using i.e.: (a) inchworm design and (b) quadrupedal design. The similarities between the inchworm and quadrupedal design are both use pressure input for motion. The SCRs also bend by using the expansion of chambers at their body. Both designs have the same length fixed at 86mm, but with different topology. The design optimization for maximum bending motion with respect to input pressure were evaluated using Finite Element Method (FEM) via Abaqus software, where the results shows that the highest bending was observed for the inchworm design. The maximum bending value (extension) of 130.4 mm was obtained with the optimized parameters set at 4mm base thickness, 5mm chamber gap, and 2mm width for the air chamber, respectively.

Угловые характеристики сенсора коэффициента преломления на основе отражательного интерферометра

The angular properties of sensor, implemented in Kretschmann’s scheme, where the optimized for oblique incidence of light thin-film reflection interferometer acts as a sensing element, are described in the paper. Analytical equations, defining the sensor’s properties for S and P polarization states at working wavelength in vicinity of working angle of incidence, are provided, as well as approximate equations for main parameters of sensor: sensitivity, angular full width at half maximum, contrast and figure of merit. The possibility to vary the named parameters by choosing appropriate metal and dielectric layers of the structure is shown. For an example, the numerical calculations are made for one of special cases, optimized for S polarization state, as having larger figures of merit. The dependencies of angular properties on number of layers and base thickness are demonstrated. It is shown, that angular measurements with this method are theoretically capable of infinite figures of merit, and in practice they are only limited by losses in layered structure and beam divergency. The recommendations for experimental realization of method are given.

Theoretical study of spectral responses of heterojunctions based on CuInSe2 and CuInS2

In this work we study the spectral responses of thin films solar cells of heterojunctions based on CuInSe2 and CuInS2. Four-layer structures are studied according to the n+n/pp+ model. First we consider the structure ZnO(n+)/CdS(n)/CuInS2(p)/CuInSe2(p+) where CuInS2 represent the base and CuInSe2 the substrate in this model. Secondly we consider the structure ZnO(n+)/CdS(n)/CuInSe2(p)/ CuInS2(p+), for this model CuInSe2 represent the base and CuInS2 the substrate. ZnO and CdS are used as window layers in each structure. Using the continuity equation that governs transport of carriers in semiconductor material, models for calculating spectral responses are proposed for heterojunctions type n+n/pp+ based on CuInSe2 and CuInS2. For each structure we have presented the energy band diagram based on the Anderson model [1] and determined the expression of the photocurrent. The theoretical results obtained allow to compare the performances of these two models by optimizing the different parameters of each structure (base thickness, diffusion length, recombination velocity at the interface, etc.) in order to improve the overall efficiency of the collection of carriers.

Effects of Denture Base Thicknesses and Reinforcement on Fracture Strength in Mandibular Implant Overdenture with Bar Attachment: Under Various Acrylic Resin Types

Objective This study aimed to assess the effect of reinforcement, denture base thickness, and acrylic resin types on dynamic and static fracture strength in mandibular implant overdentures with bar attachment. Materials and Methods One hundred and eight experimental mandibular implant overdentures with bar attachments were fabricated in three main groups, namely unreinforced (control: C), reinforced with unidirectional glass fibers (FR), and Co–Cr cast metal (MR). Each group included denture bases of 2-, 3-, and 4-mm thicknesses and produced with conventional (CA) and high-impact acrylic (HIA) resins. Specimens were thermocycled (5,000 times, 5–55°C) then subjected to a 400,000 cyclic load regime. Unbroken specimens were then loaded until fracture by a universal testing machine. Differences in mean fracture resistance among the groups were compared using the one-way analysis of variance (with post hoc Tukey's honestly significant difference test) and Student's t-tests (α = 0.05). Results Fracture strength increased significantly when the denture base thickness was increased (p = 0.001). The 2-mm denture base thickness was not enough for reinforcement. The fracture strength of the FR groups was significantly higher than other groups for 3- and 4-mm thicknesses (p = 0.001). The fracture strength of the HIA resin was significantly higher than CA resin in FR groups (p = 0.029 and p = 0.001). MR groups showed the weakest fracture strength. Conclusions The 2-mm denture base thickness had sufficient fracture strength without reinforcement and a positive relationship between acrylic resin thickness and fracture resistance was found.