Nonlinear Elastic Material Property Estimation of Lower Extremity Residual Limb Tissues

The interface stresses between the residual limb and prosthetic socket have been studied to investigate prosthetic fit. Finite-element models of the residual limb-prosthetic socket interface facilitate investigation of the mechanical interface and may serve as a potential tool for future prosthetic socket design. However, the success of such residual limb models to date has been limited, in large part due to inadequate material formulations used to approximate the mechanical behavior of residual limb soft tissues. Nonlinear finite-element analysis was used to simulate force-displacement data obtained during in vivo rate-controlled (1, 5, and 10 mm/s) cyclic indentation of the residual limb soft tissues of seven individuals with transtibial amputation. The finite-element models facilitated determination of an appropriate set of nonlinear elastic material coefficients for bulk soft tissue at discrete clinically relevant test locations. Axisymmetric finite-element models of the residual limb bulk soft tissue in the vicinity of the test location, the socket wall and the indentor tip were developed incorporating contact analysis, large displacement, and large strain, and the James-Green-Simpson nonlinear elastic material formulation. Model dimensions were based on medical imaging studies of the residual limbs. The material coefficients were selected such that the normalized sum of square error (NSSE) between the experimental and finite-element model indentor tip reaction force was minimized. A total of 95% of the experimental data were simulated using the James-Green-Simpson material formulation with an NSSE less than 5%. The respective James-Green-Simpson material coefficients varied with subject, test location, and indentation rate. Therefore, these coefficients cannot be readily extrapolated to other sites or individuals, or to the same site and individual some time after testing

Proof of concept of diffuse optical tomography using time-of-flight range imaging cameras

Diffuse optical tomography is an optical technique to create 3-dimensional images of the inside of highly scattering material. Research groups around the world have been developing imaging systems using various source-detector arrangements to determine optical properties of biological tissue with a focus on medical applications. In this paper we investigate whether a range imaging camera can be used as a detector array. We used time-of-flight range imaging cameras instead of the conventional source-detector array used by others. The results provided in this paper show reconstructed images of absorption and reduced scattering of an object submerged in a tissue simulating phantom. Using the ranging camera XZ422 Demonstrator and the NIRFAST software package, we reconstructed 2D images of a 6 mm metal rod submerged in the centre of a 5 cm deep tank filled with 1% IntralipidTM. We have shown for the first time that range imaging cameras can replace the traditional detectors in diffuse optical tomography

Device Modelling of Silicon Based High-Performance Flexible Electronics

The area of flexible electronics is rapidly expanding and evolving. With applications requiring high speed and performance, ultra-thin silicon-based electronics has shown its prominence. However, the change in device response upon bending is a major concern. In absence of suitable analytical and design tool friendly model, the behavior under bent condition is hard to predict. This poses challenges to circuit designer working in the bendable electronics field, in laying out a design that can give a precise response in a stressed condition. This paper presents advances in this direction and investigates the effect of compressive and tensile stress on the performance of NMOS and PMOS transistor and a touch sensor comprising a transistor and piezoelectric capacitor

Bio-Inspired Robotics Based on Liquid Crystalline Elastomers(LCEs) and Flexible Stimulators

Soft robotics are most inspired from animals harnessing soft structures to move on ground or even harsh topological surface. Soft materials are the primary composition of soft robotics. Although they are not as durable and strong as ceramics and metals, soft materials stand out for their reversibility of deformation, response to stimuli and bio-compatibility. In this dissertation, liquid crystalline elastomer(LCE) combined with patterned flexible electronics and liquid metal have been used as soft robotics that simulating different kinds of worm-like movement. Besides, the impressive bendability of LCE finds itself a lot of potential in nature-camouflage area.First of all, the conception of soft robotics was deeply dug out through references about smart materials, for example, shape memory alloy(SMA), shape memory polymer(SMP), liquid crystalline elastomer(LCE) and etc. In this dissertation, LCE, as an advanced smart material, is used to fabricate soft robots, simulating inchworm movement. Another key point is the designation of actuator, in the research, flexible electronics were integrated onto LCE strip, when voltage was applied, the electronics increased temperature of specific part on one side of strip. Temperature difference between top and bottom surface induced LCE bending to approach anticipated location. Several cycles of inchworm movement were achieved, change in actuation sequence induces an inverse movement direction.Secondly, an improvement was carried out for crawling robots with combination of liquid metal(LM). Different from flexible electronics which are actually solid, “liquid electronics” suits more in the term “flexible”. Liquid metal was introduced into the research due to elevated requirement of bending curvature for its freely and reversibly transition between solid and liquid. New attachment approach was carried out using passive PDMS layer embedding to solidify contact between liquid metal and LCE. As consequence, the soft robotics could grasp a stick and move itself towards bi-direction. Repeatability test was conducted for the composite bending, twisting and shrinking.Last but not the least, the LCE/LM system patterned in different shape could easily camouflage itself as black agaric, seaweed and origami pentagram, in another word, the potential application in camouflage of this structure was developed. In specific parts of passive eco-flex layer, LCE segments were embedded and connected by liquid metal channels. For example, to simulate black agaric, four or five spots of the system were expected to bend, when external input was applied, LM in these areas generate and conduct heat around causing bending and maintaining the system at a specific shape, also, black paints were cast onto composite in advance. Repeatability test was conducted and reported

A type of simulation which some experimental evidence suggests we don't live in

Do we live in a computer simulation? I will present an argument that the results of a certain experiment constitute empirical evidence that we do not live in, at least, one type of simulation. The type of simulation ruled out is very specific. Perhaps that is the price one must pay to make any kind of Popperian progress

Bit error performance of diffuse indoor optical wireless channel pulse position modulation system employing artificial neural networks for channel equalisation

The bit-error rate (BER) performance of a pulse position modulation (PPM) scheme for non-line-of-sight indoor optical links employing channel equalisation based on the artificial neural network (ANN) is reported. Channel equalisation is achieved by training a multilayer perceptrons ANN. A comparative study of the unequalised `soft' decision decoding and the `hard' decision decoding along with the neural equalised `soft' decision decoding is presented for different bit resolutions for optical channels with different delay spread. We show that the unequalised `hard' decision decoding performs the worst for all values of normalised delayed spread, becoming impractical beyond a normalised delayed spread of 0.6. However, `soft' decision decoding with/without equalisation displays relatively improved performance for all values of the delay spread. The study shows that for a highly diffuse channel, the signal-to-noise ratio requirement to achieve a BER of 10−5 for the ANN-based equaliser is ~10 dB lower compared with the unequalised `soft' decoding for 16-PPM at a data rate of 155 Mbps. Our results indicate that for all range of delay spread, neural network equalisation is an effective tool of mitigating the inter-symbol interference

Learning while Competing -- 3D Modeling & Design

The e-Yantra project at IIT Bombay conducts an online competition, e-Yantra Robotics Competition (eYRC) which uses a Project Based Learning (PBL) methodology to train students to implement a robotics project in a step-by-step manner over a five-month period. Participation is absolutely free. The competition provides all resources - robot, accessories, and a problem statement - to a participating team. If selected for the finals, e-Yantra pays for them to come to the finals at IIT Bombay. This makes the competition accessible to resource-poor student teams. In this paper, we describe the methodology used in the 6th edition of eYRC, eYRC-2017 where we experimented with a Theme (projects abstracted into rulebooks) involving an advanced topic - 3D Designing and interfacing with sensors and actuators. We demonstrate that the learning outcomes are consistent with our previous studies [1]. We infer that even 3D designing to create a working model can be effectively learned in a competition mode through PBL

Tinjauan terhadap pengetahuan, kemahiran dan minat dalam bidang keusahawanan di kalangan peserta kursus jangka pendek anjuran Jabatan Pendidikan Teknik dan Vokasional

The purpose of this research is to determine the knowledge, skill and enthusiasm among participants short term course organized by Jabatan Pendidikan Teknik dan Vokasional (JPTV). Fifty-four participants from three short term courses, Kursus Usahawan Berasas Kimpalan, Kursus Penyelenggaraan dan Pemasangan Komputer dan Kursus Chargeman AO are selected as respondents to gather feedbacks based on the questionnaire distributed. Collected data is analyzed by using Statistical Package For Social Science (SPSS), 11.0 version, which were represented using mean scores, percentage and Correlations Pearson. The result of this research shows that majority of the participants are enthusiasm towards entrepreneurship but they are lack of knowledge and skill in entrepreneurship basic. "Garis Panduan Asas Keusahawanan " had been created to give knowledge and skill entrepreneurship basic for participants short term course organized by JPTV