Design of Engineered Elastomeric Substrate for Stretchable Active Devices and Sensors

In the field of flexible electronics, emerging applications require biocompatible and unobtrusive devices, which can withstand different modes of mechanical deformation and achieve low complexity in the fabrication process. Here, the fabrication of a mesa‐shaped elastomeric substrate, supporting thin‐film transistors (TFTs) and logic circuits (inverters), is reported. High‐relief structures are designed to minimize the strain experienced by the electronics, which are fabricated directly on the pillars' surface. In this design configuration, devices based on amorphous indium‐gallium‐zinc‐oxide can withstand different modes of deformation. Bending, stretching, and twisting experiments up to 6 mm radius, 20% uniaxial strain, and 180° global twisting, respectively, are performed to show stable electrical performance of the TFTs. Similarly, a fully integrated digital inverter is tested while stretched up to 20% elongation. As a proof of the versatility of mesa‐shaped geometry, a biocompatible and stretchable sensor for temperature mapping is also realized. Using pectin, which is a temperature‐sensitive material present in plant cells, the response of the sensor shows current modulation from 13 to 28 °C and functionality up to 15% strain. These results demonstrate the performance of highly flexible electronics for a broad variety of applications, including smart skin and health monitoring.     

Zero-tillage is a proven technology for sustainable wheat intensification in the Eastern Indo-Gangetic Plains: what determines farmer awareness and adoption?

In India, there is increasing recognition among policy-makers of the largely untapped potential of the Eastern Indo-Gangetic Plains (IGP) for meeting state- and national-level food needs. Zero-tillage (ZT) is a proven technology for enhancing wheat productivity and, hence, food security in the IGP, while reducing production costs – a ‘win-win’ scenario that should support rapid technology scaling even though adoption remains modest to date. In order to inform policies and derive recommendations for a more effective extension strategy, this study investigated determinants of ZT adoption in the Eastern IGP using a random sample of 1000 wheat-growing households from Bihar, stratified by ZT adoption status. We corrected for potential non-exposure bias by using a two-stage estimation procedure that differentiates between factors affecting farmers’ awareness of ZT and those affecting adoption conditional on awareness. Owing to the relatively nascent stage of ZT diffusion in the area, we emphasized the role of information in the adoption process, including social networks, whereby we allowed for endogenous and exogenous network effects. Only 44% of sample households knew about ZT technology, and there was substantial scale bias in favor of larger scale farmers both with respect to awareness and adoption. Both the adoption behavior and characteristics of the respondents’ network members influenced their own awareness and adoption of ZT, particularly among farmers in the smallest landholding tercile. Farmers valued the time-saving potential of ZT, especially under conditions of increasingly unreliable monsoon rains resulting in a delayed rice crop and, consequently, late establishment of wheat which reduces yield. The fact that most farmers accessed ZT via custom-hire services was accounted for in the model, and the importance of proximate service providers confirmed. We conclude that there is need for further awareness-raising campaigns for ZT technology, whereby, apart from mass media, agricultural extension should use contact farmers belonging to different social strata for effective within-village diffusion of messages, especially to the poorer farmers. The social inclusiveness of ZT use can be enhanced by supporting the emergence of more ZT service providers and by developing business models that lower the transaction costs of servicing smaller farms.     

Light transport in three-dimensional semi-infinite scattering media

The three-dimensional radiative transfer equation is solved for modeling the light propagation in anisotropically scattering semi-infinite media such as biological tissue, considering the effect of internal reflection at the interfaces. The two-dimensional Fourier transform and the modified spherical harmonics method are applied to derive the general solution to the associated homogeneous problem in terms of analytical functions. The obtained solution is used for solving boundary-value problems, which are important for applications in the biomedical optics field. The derived equations are successfully verified by comparisons with Monte Carlo simulations.     

Influence of Solute Content and Solidification Parameters on Grain Refinement of Aluminum Weld Metal

Grain refinement provides an important possibility to enhance the mechanical properties (e.g., strength and ductility) and the weldability (susceptibility to solidification cracking) of aluminum weld metal. In the current study, a filler metal consisting of aluminum base metal and different amounts of commercial grain refiner Al Ti5B1 was produced. The filler metal was then deposited in the base metal and fused in a GTA welding process. Additions of titanium and boron reduced the weld metal mean grain size considerably and resulted in a transition from columnar to equiaxed grain shape (CET). In commercial pure aluminum (Alloy 1050A), the grain-refining efficiency was higher than that in the Al alloys 6082 and 5083. Different welding and solidification parameters influenced the grain size response only slightly. Furthermore, the observed grain-size reduction was analyzed by means of the undercooling parameter P and the growth restriction parameter Q, which revealed the influence of solute elements and nucleant particles on grain size.     

Design of an upgradeable 45–100 mA RFQ accelerator for FAIR

A 325 MHz, 35 mA, 3 MeV Radio-Frequency Quadrupole (RFQ) accelerator will be operated as the first accelerating structure of the proton linac injector for the newly planned international science center Facility for Antiproton and Ion Research (FAIR) at GSI, Germany. In previous design studies, two high beam intensities, 70 and 100 mA, were used. Most recently, the design intensity has been changed to 45 mA, which is closer to the operational value. Taking advantage of the so-called New Four-Section Procedure, a new design, which is upgradable from 45 to 100 mA, has been developed for the FAIR proton RFQ. Besides the upgradability analyses, robustness studies of the new design to spatial displacements of the input beam and field errors are presented as well.     

Detection of Plaque in Coronary Artery in CMRI Images and 3D Visualization of Blood Flow

Detection of blocks in coronary arteries is becoming crucial interest for early detection of heart attacks. In this paper we propose a framework for detection of plaque in coronary arteries from cardio vascular magnetic resonance imaging(CMRI). It is a quantitative tool for the assessment of cardiovascular diseases. First, select a region of interest and segment the region of coronary artery using enhanced region based active contour (ERAC). Secondly the centreline extraction and lumen segmentation are integrated to extract the artery centreline using geometric moments and the vessel direction using Hessian matrix and segment the vessel lumen in each slice using ERAC. A boundary searching method is adapted to fine tune the segmented surface in each slice of CMRI image. Third, the soft plaques in the coronary artery are extracted by thresholding the segmented region. Finally a 3D visualization of blood flow in coronary artery is presented and the volume of blood flow is calculated. In the experiments we have employed 22 datasets of CMRI images. The experimental results show an average accuracy of 97.6% and with a mean and standard deviation of false discovery rate of 2.48 ± 0.002.

     

The influence of the lateral filament texture on the compressive properties of PpPTA aramid filaments

A series of PpPTA aramid fibres with various degree of lateral orientation ranging from their usual radial-oriented lateral texture to a full random lateral texture were prepared by employing a series of different coagulating media in the fibre spinning process. The resulting variation in lateral texture did not lead to differences in linear tensile properties or crystallite dimensions. Raman spectroscopy measurements on embedded axially compressed filaments showed that the stresses for kink band initiation and propagation were independent of the degree of lateral texture. The kink band morphology and the final kink band density upon further straining were found to correlate with the shear modulus derived from combined mechanical and XRD data.     

Electromyographical indication of muscular fatigue in occupational field studies

Surface electromyography offers a valuable tool for the indication of muscular fatigue in occupational field studies. For this purpose, the time course of the electromyogram (EMG) has to be analysed, in order to detect typical fatigue-induced changes such as an increase in EMG amplitude or a shift in the spectral distribution towards lower frequencies. Such procedures need a detailed knowledge about the actual activity of the person and muscle under test for the total working time. This can be attained by encoding the activity of the person during the work and recording an electrical code signal together with the electrophysiological signals. For the indication of muscle fatigue, EMGs for situations connected with similar muscle load should only be compared, since the EMG amplitude as well as the spectrum do not only depend upon the fatigue state, but also upon the produced muscle force. This demand can be fulfilled by (i) interrupting the work and performing test contractions of known force in a predefined body posture or (ii) by comparing situations connected with a certain reference activity. (iii) In a recently developed approach for the joint analysis of EMG amplitude and spectrum (JASA) changes in the amplitude and the spectrum are considered simultaneously. This method permits the discrimination between fatigue-induced and force-related EMG changes. Using this procedure, changes in the EMG can be attributed to categories like fatigue or recovery as well as increase or decrease in the force production of the muscle under test. Applications from field studies during manual materials handling in a weaving mill, price recording at scanner checkouts in a supermarket and the performance of surgical work using endoscopic operation techniques in urology demonstrate the appropriateness of electromyography for fatigue indication in occupational physiology and ergonomics. Nevertheless, the commonly used measures of muscular fatigue such as increase in EMG amplitude and left shift in EMG spectrum are primarily related to the electrical activation and its propagation along the muscle fibres. Their connection to the fatigue-induced reduction in the force generating capacity of the muscle under test includes complex physiological implications. Therefore, the need for further development of fatigue indicators which are more directly related to muscular force is recognized.

Relevance to industry

In occupational health and ergonomics indication of muscular fatigue is needed, since activities inducing muscular fatigue can be performed for a limited time, only, and the quality of work can be influenced negatively. Electromyography offers valuable tools for the indication of fatigue and the appropriate assessment of ergonomic design measures.