Hot pressing process ameliorates internal defects of PBZ/PVDF composite film for a high electrocaloric effect near room temperature

The poor interface compatibility between inorganic fillers and organic polymer matrix in nanocomposite has presented considerable challenges, which limit the applicable electric field ranges and reduce the interface polarization interaction. In this paper, Pb[Formula: see text]Ba[Formula: see text]ZrO3 (PBZ) nanofibers were introduced into the polyvinylidene fluoride (PVDF) matrix to prepare composite film, and the effect of hot pressing on interface compatibility was investigated at volume composite ratios of 3% and 4%. For the untreated film, [Formula: see text] and [Formula: see text] of the 3 vol.% composite film are 9.68 [Formula: see text]C/cm2 and 401 MV/m, respectively, and those for the 4 vol.% composite film are 9.15 [Formula: see text]C/cm2 and 408 MV/m, respectively. These differences are mainly due to the impact of internal defects. After hot pressing, [Formula: see text] and [Formula: see text] for the 3 vol.% composite film became 10.22 [Formula: see text]C/cm2 and 490 MV/m, respectively. Those for the 4 vol.% composite film are 9.85 [Formula: see text]C/cm2 and 485 MV/m. Experiment and simulation results showed the beneficial effect of hot pressing, which ameliorated poor interfacial compatibility, reduced internal defects, and improved the crystallinity of the composite film. A high electrocaloric effect (ECE) was obtained by using the direct measure method. At −30[Formula: see text]C, the [Formula: see text] values of hot-pressed PBZ/PVDF film at 3[Formula: see text] and 4[Formula: see text] vol.% were 23.81 and 19.73 K, respectively. When temperature increased to 70[Formula: see text]C, the [Formula: see text] values were 9.44 and 7.01 K, respectively, which were 1.58 times of the values of a non-hot-pressed film. These results indicated that hot pressing alleviated the interface problem and resulted in high EC performance under a high-strength electric field.

A Novel Development of TRIZ-Analogic Construction Interface Problem Identification and Solutions Framework

One of the critical factors of project success is the interface management. Past project interface management mainly relies on knowledge and experience of the project managers. The existing studies of project interface management also mainly focused on the definition and the classification of project interfaces. There is no workable and flexible framework for construction interface problem identification and solutions. This study conducted an analogic study of contradiction matrix at Theory of Inventive Problem Solving (TRIZ) to develop such a framework. This research collected around six hundred interface management cases from civil works and building projects. For comparison, this research defined an experimental group (TRIZ case) and a control group (experience-oriented solution case) based on the concept of clinical experiments in medical science to evaluate and improve the rationality of the matrix. Subsequently, based upon the theory of information retrieval (IR), this research conducted statistical evaluation and TRIZ features remedies to develop generalized construction interface problem identification and solutions. For solving project management interface problems, the TRIZ-analogic construction interface problem identification and solutions framework provides a systematic approach to develop more robust solutions for interface problems in construction engineering rather than just simply relying on intuitive experience.

A 3D CAD model input pipeline for REFMUL3 full-wave FDTD 3D simulator

The use of advanced simulation has become increasingly more important in the planning, design, and assessment phases of future fusion plasma diagnostics, and in the interpretation of experimental data from existing ones. The design cycle of complex reflectometry systems, such as the ones being planned for next generation machines (IDTT and DEMO), relies heavily on the results produced by synthetic diagnostics, used for system performance evaluation and prediction, both crucial in the design process decision making. These synthetic diagnostics need realistic representations of all system components to incorporate the main effects that shape their behavior. Some of the most important elements that are required to be well modelled and integrated in simulations are the wave launcher structures, such as the waveguides, tapers, and antennas, as well as the vessel wall structures and access to the plasma. The latter are of paramount importance and are often neglected in this type of studies. Faithfully modelling them is not an easy task, especially in 3D simulations. The procedure herein proposed consists in using CAD models of a given machine, together with parameterizable models of the launcher, to produce a description suited for Finite Difference Time Domain (FDTD) 3D simulation, combining the capabilities of real-world CAD design with the power of simulation. However, CAD model geometric descriptions are incompatible with the ones used by standard FDTD codes. CAD software usually outputs models in a tessellated mesh while FDTD simulators use Volumetric Pixel (VOXEL) descriptions. To solve this interface problem, we implemented a pipeline to automatically convert complex CAD models of tokamak vessel components and wave launcher structures to the VOXEL input required by REFMUL3, a full wave 3D Maxwell FDTD parallel code. To illustrate the full procedure, a complex reflectometry synthetic diagnostic for IDTT was setup, converted and simulated. This setup includes 3 antennas recessed into the vessel wall, for thermal protection, one for transmission and reception, and two just for reception.

Hypoplastic Interface Model considering Plane Strain Condition and Surface Roughness

The soil-structure interface problem is an important part of soil-structure interaction research. These problems are mostly three-dimensional space problems, which is more complex to solve. In this paper, reduced stress and strain rate vectors are incorporated into the explicitly granular hypoplastic model by considering the plane strain state precisely. In addition, considering the important influence of roughness on the mechanical properties of contact surface, an improved hypoplastic model is established by incorporating the influence of roughness into the hypoplastic model, and the applicability of the new improved model is validated by comparing with the simulation results of the Mohr–Coulomb model, the explicitly granular hypoplastic models, and the experimental data. The results indicate that the improved model can be utilized to reflect the nonlinearity of the mechanical properties of the contact surface, which is in good agreement with the experimental data.

No Interface, No Problem: Gesture Recognition on Physical Objects Using Radar Sensing

Physical objects are usually not designed with interaction capabilities to control digital content. Nevertheless, they provide an untapped source for interactions since every object could be used to control our digital lives. We call this the missing interface problem: Instead of embedding computational capacity into objects, we can simply detect users’ gestures on them. However, gesture detection on such unmodified objects has to date been limited in the spatial resolution and detection fidelity. To address this gap, we conducted research on micro-gesture detection on physical objects based on Google Soli’s radar sensor. We introduced two novel deep learning architectures to process range Doppler images, namely a three-dimensional convolutional neural network (Conv3D) and a spectrogram-based ConvNet. The results show that our architectures enable robust on-object gesture detection, achieving an accuracy of approximately 94% for a five-gesture set, surpassing previous state-of-the-art performance results by up to 39%. We also showed that the decibel (dB) Doppler range setting has a significant effect on system performance, as accuracy can vary up to 20% across the dB range. As a result, we provide guidelines on how to best calibrate the radar sensor.

Electromagnetic Mode Matching in a Wilson Basis --- Optical Fiber Connections with a Gap

On the basis of two optical fibers with an optional lateral and longitudinal displacement in a homogeneous background medium, we describe a general full-vectorial Wilson-basis discretized mode-matching method that evaluates the converged electromagnetic fields after all resonances in the possible gap cavity have settled. Wilson basis functions feature strong localization in both the spatial and the spectral domain, which allows for efficient modal electromagnetic field expansions, adequate truncation of field propagation operators, and sparse translation operators, which in turn allow to make ad hoc electromagnetic field-matching operators. For physical contact connections between single-mode fibers with a mode-field diameter mismatch, we obtain attenuation curves that are right between those obtained from approximation methods that either effectively match the electric field or the magnetic field under the assumption of a vanishing reflection. For fibers separated by a growing gap, constructive and destructive interference patterns in the cavity are computed by the successive application of Love's equivalence principle and the propagation operator. By leveraging the physical width of the Wilson basis functions and the stepsize of the propagation operator, the initial operators may be reused in solving the interface problem for other wavelengths. For multi-mode fiber connections, we provide attenuation curves on a modal electromagnetic field level, as well as for overfilled and core-confined target encircled-flux compliant launches. A comparison to geometrical-optics based approaches shows attenuation differences in the order of several hundredth of a dB, and although that is small, it is significant for modern connection attenuation specifications. In the final example of connections between regular and trench-assisted multi-mode fibers, we notice that the relative change in the cumulative near-field power distribution can be significant, despite a marginally small attenuation. The influence of a core diameter and/or numerical aperture mismatch can be examined with a deliberate lateral misalignment.

A Module-Linking Graph Assisted Hybrid Optimization Framework for Custom Analog and Mixed-Signal Circuit Parameter Synthesis

Analog and mixed-signal (AMS) computer-aided design tools are of increasing interest owing to demand for the wide range of AMS circuit specifications in the modern system on a chip and faster time to market requirement. Traditionally, to accelerate the design process, the AMS system is decomposed into smaller components (called modules ) such that the complexity and evaluation of each module are more manageable. However, this decomposition poses an interface problem, where the module’s input-output states deviate from when combined to construct the AMS system, and thus degrades the system expected performance. In this article, we develop a tool module-linking-graph assisted hybrid parameter search engine with neural networks (MOHSENN) to overcome these obstacles. We propose a module-linking-graph that enforces equality of the modules’ interfaces during the parameter search process and apply surrogate modeling of the AMS circuit via neural networks. Further, we propose a hybrid search consisting of a global optimization with fast neural network models and a local optimization with accurate SPICE models to expedite the parameter search process while maintaining the accuracy. To validate the effectiveness of the proposed approach, we apply MOHSENN to design a successive approximation register analog-to-digital converter in 65-nm CMOS technology. This demonstrated that the search time improves by a factor of 5 and 700 compared to conventional hierarchical and flat design approaches, respectively, with improved performance.

A regularity result for minimal configurations of a free interface problem

We prove a regularity result for minimal configurations of variational problems involving both bulk and surface energies in some bounded open region $$\varOmega \subseteq {\mathbb {R}}^n$$ Ω ⊆ R n . We will deal with the energy functional $${\mathscr {F}}(v,E):=\int _\varOmega [F(\nabla v)+1_E G(\nabla v)+f_E(x,v)]\,dx+P(E,\varOmega )$$ F ( v , E ) : = ∫ Ω [ F ( ∇ v ) + 1 E G ( ∇ v ) + f E ( x , v ) ] d x + P ( E , Ω ) . The bulk energy depends on a function v and its gradient $$\nabla v$$ ∇ v . It consists in two strongly quasi-convex functions F and G, which have polinomial p-growth and are linked with their p-recession functions by a proximity condition, and a function $$f_E$$ f E , whose absolute valuesatisfies a q-growth condition from above. The surface penalization term is proportional to the perimeter of a subset E in $$\varOmega $$ Ω . The term $$f_E$$ f E is allowed to be negative, but an additional condition on the growth from below is needed to prove the existence of a minimal configuration of the problem associated with $${\mathscr {F}}$$ F . The same condition turns out to be crucial in the proof of the regularity result as well. If (u, A) is a minimal configuration, we prove that u is locally Hölder continuous and A is equivalent to an open set $${\tilde{A}}$$ A ~ . We finally get $$P(A,\varOmega )={\mathscr {H}}^{n-1}(\partial {\tilde{A}}\cap \varOmega $$ P ( A , Ω ) = H n - 1 ( ∂ A ~ ∩ Ω ).