Fabrication and transport critical currents of multifilamentary MgB2/Fe wires and tapes

Multifilamentary MgB2/Fe wires and tapes with high transport critical current densities have been fabricated using a straightforward powder-in-tube (PIT) process. After annealing, we measured transport jc values up to 1.1 * 105 A/cm2 at 4.2 K and in a field of 2 T in a MgB2/Fe square wire with 7 filaments fabricated by two-axial rolling, and up to 5 * 104 A/cm2 at 4.2 K in 1 T in a MgB2/Fe tape with 7 filaments. For higher currents these multifilamentary wires and tapes quenched due to insufficient thermal stability of filaments. Both the processing routes and deformation methods were found to be important factors for fabricating multifilamentary MgB2 wires and tapes with high transport jc values.Comment: 13 pages, 7 figure

800 nm WDM interrogation system for strain, temperature, and refractive index sensing based on tilted fiber Bragg grating

A low-cost high-resolution wavelength-division-multiplexing (WDM) interrogation system operating around 800 nm region with operational bandwidth up to 60 nm and resolution of 12.7 pm utilizing a tilted fiber Bragg grating (TFBG) and a CCDarray detector has been implemented. The system has been evaluated for interrogating fiber Bragg grating based strain, temperature sensors, giving sensitivities of 0.59 pm/µe and 5.6 pm/°C, which are in good agreement with previously reported values. Furthermore, the system has been utilized to detect the refractive index change of sample liquids, demonstrating a capability of measuring index change as small as 10¯5. In addition, the vectorial expression of phase match condition and fabrication of TFBG have been discussed

Polarisation mode coupling of excessively tilted fibre Bragg gratings with directional transverse loading

We report a distinctive polarisation mode coupling behaviour of tilted fibre Bragg gratings (TFBGs) with tilted angle exceeding 45°. The ex-45° TFBGs exhibit pronounced polarisation mode splitting resulted from grating structure asymmetry induced birefringence. We have studied and analysed the property of ex-45° TFBGs under transverse load applied to their equivalent fast- and slow-axis. The results show that the coupling between the orthogonally polarised modes takes place only when the load is applied to its fast-axis, giving a prominent directional loading response. This transverse load related polarisation property may be exploitable for implementation of optical fibre vector sensors capable of measuring the magnitude and orientation of the applied transverse load

Tilted fibre Bragg grating based 800nm WDM interrogation system for strain, temperature and refractive index sensing

We report the implementation of a low-cost high-resolution WDM interrogation system operating around 800nm region with bandwidth up to 60 nm and resolution of 13 pm by utilising a tilted fibre Bragg grating as an out-coupling device and a CCD-array detector. The system has been evaluated for interrogating fibre Bragg grating based strain, temperature sensors, giving sensitivities of 0.6 pm/µe and 5.6 pm/°C which are in good agreement with previously reported values. Furthermore, the system has been utilised to detect refractive index change of sample liquids, demonstrating a capability of measuring index change as small as 10-5

Adaptive polarization-difference transient imaging for depth estimation in scattering media

Introducing polarization into transient imaging improves depth estimation in participating media, by discriminating reflective from scattered light transport and calculating depth from the former component only. Previous works have leveraged this approach under the assumption of uniform polarization properties. However, the orientation and intensity of polarization inside scattering media is nonuniform, both in the spatial and temporal domains. As a result of this simplifying assumption, the accuracy of the estimated depth worsens significantly as the optical thickness of the medium increases. In this Letter, we introduce a novel adaptive polarization-difference method for transient imaging, taking into account the nonuniform nature of polarization in scattering media. Our results demonstrate a superior performance for impulse-based transient imaging over previous unpolarized or uniform approaches

A Fuzzy-Interval Dynamic Optimization Model for Regional Water Resources Allocation under Uncertainty

In this study, a fuzzy-interval dynamic programming (FIDP) model is proposed for regional water management under uncertainty by combining fuzzy-interval linear programming (FILP) and dynamic programming (DP). This model can not only tackle uncertainties presented as intervals, but also consider the dynamic characteristics in the allocation process for water resources. Meanwhile, the overall satisfaction from users is considered in the objective function to solve the conflict caused by uneven distribution of resources. The FIDP model is then applied to the case study in terms of water resources allocation under uncertainty and dynamics for the City of Handan in Hebei Province, China. The obtained solutions can provide detailed allocation schemes and water shortage rates at different stages. The calculated comprehensive benefits of economy, water users’ satisfaction and pollutant discharge (i.e., COD) are [2264.72, 2989.33] × 108 yuan, [87.50, 96.50] % and [1.23, 1.65] × 108 kg respectively with a plausibility degree (i.e., λ±opt) ranging within [0.985, 0.993]. Moreover, the benefit from FIDP model under consideration of dynamic features is more specific and accurate than that of FILP model, whilst the water shortage rate from FIDP is [5.10, 9.10] % lower than that of FILP model.This research was supported by Nation Natural Science Foundation of China (61873084), and Natural Science Foundation of Hebei, in China (D2019402235)

Mechanical theory of the film-on-substrate-foil structure : curvature and overlay alignment in amorphous silicon thin-film devices fabricated on free-standing foil substrates

Flexible electronics will have inorganic devices grown at elevated temperatures on free-standing foil substrates. The thermal contraction mismatch between the substrate and the deposited device films, and the built-in stresses in these films, cause curving and a change in the in-plane dimensions of the workpiece. This change causes misalignment between the device layers. The thinner and more compliant the substrate, the larger the curvature and the misalignment. We model this situation with the theory of a bimetallic strip, which suggests that the misalignment can be minimized by tailoring the built-in stress introduced during film growth. Amorphous silicon thin-film transistors (a-Si:H TFTs) fabricated on stainless steel or polyimide (PI) (Kapton E®) foils need tensile built-in stress to compensate for the differential thermal contraction between the silicon films and the substrate. Experiments show that by varying the built-in stress in just one device layer, the gate silicon nitride (SiNx), one can reduce the misalignment between the source/drain and the gate levels from ∼400 parts-per-million to ∼100 parts-per-million

Sintering Kinetics of Plasma-Sprayed Zirconia TBCs

A model of the sintering exhibited by EB-PVD TBCs, based on principles of free energy minimization, was recently published by Hutchinson et al. In the current paper, this approach is applied to sintering of plasma-sprayed TBCs and comparisons are made with experimental results. Predictions of through-thickness shrinkage and changing pore surface area are compared with experimental data obtained by dilatometry and BET analysis respectively. The sensitivity of the predictions to initial pore architecture and material properties are assessed. The model can be used to predict the evolution of contact area between overlying splats. This is in turn related to the through-thickness thermal conductivity, using a previously-developed analytical model

Anatomic Insights into Disrupted Small-World Networks in Pediatric Posttraumatic Stress Disorder.

Purpose To use diffusion-tensor (DT) imaging and graph theory approaches to explore the brain structural connectome in pediatric posttraumatic stress disorder (PTSD). Materials and Methods This study was approved by the relevant research ethics committee, and all participants’ parents or guardians provided informed consent. Twenty-four pediatric patients with PTSD and 23 control subjects exposed to trauma but without PTSD were recruited after the 2008 Sichuan earthquake. The structural connectome was constructed by using DT imaging tractography and thresholding the mean fractional anisotropy of 90 brain regions to yield 90 × 90 partial correlation matrixes. Graph theory analysis was used to examine the group-specific topologic properties, and nonparametric permutation tests were used for group comparisons of topologic metrics. Results Both groups exhibited small-world topology. However, patients with PTSD showed an increase in the characteristic path length (P = .0248) and decreases in local efficiency (P = .0498) and global efficiency (P = .0274). Furthermore, patients with PTSD showed reduced nodal centralities, mainly in the default mode, salience, central executive, and visual regions (P < .05, corrected for false-discovery rate). The Clinician-Administered PTSD Scale score was negatively correlated with the nodal efficiency of the left superior parietal gyrus (r = −0.446, P = .043). Conclusion The structural connectome showed a shift toward “regularization,” providing a structural basis for functional alterations of pediatric PTSD. These abnormalities suggest that PTSD can be understood by examining the dysfunction of large-scale spatially distributed neural networks