Design Optimization Of Devices Research Articles

Waveguide-integrated high-performance magneto-optical isolators and circulators on silicon nitride platforms

Optical isolators and circulators are important components for photonic integrated circuits. Despite significant progress on silicon-on-insulator (SOI) platforms, integrated optical isolators and circulators have rarely been reported on silicon nitride (SiN) platforms. In this paper, we report monolithic integration of magneto-optical (MO) isolators on SiN platforms with record-high performances based on standard silicon photonics foundry process and MO thin film deposition. We successfully grow high-quality MO garnet thin films on SiN with large Faraday rotation up to - − 5900 d e g / c m . We show superior MO figure of merit (FoM) of MO/SiN waveguides compared to that of MO/SOI in an optimized device design. We demonstrate transverse magnetic (TM)/transverse electric (TE) mode broadband and narrowband optical isolators and circulators on SiN with high isolation ratio, low cross talk, and low insertion loss. In particular, we observe 1 dB insertion loss and 28 dB isolation ratio in a SiN racetrack resonator-based isolator at 1570.3 nm wavelength. The low thermo-optic coefficient of SiN also ensures excellent temperature stability of the device. Our work paves the way for integration of high-performance nonreciprocal photonic devices on SiN platforms.

Optimal Design of Neuroprotective Focal Brain Cooling Device Using Surrogate Model Approach

Focal brain cooling (FBC) is a treatment for refractory epilepsy to suppress epileptic discharges from an epileptic focus. Our wearable FBC system under development consists of a recirculating coolant apparatus and a battery located extracorporeally, and a cooling device made of titanium with water channels inside which is embedded in the skull. An optimal channel design of the cooling device is needed to cool the brain efficiently. Although clinical and animal studies are required to design the cooling device, the number of experiments should be reduced, and finite element (FE) simulation be utilized instead. However, trial-and-error simulations impose a heavy computational burden. One option to deal with this problem is to use surrogate modeling, which is a data-driven approach that mimics the behavior of simulation models with a low computational burden. We optimized the channel structure by combining the surrogate model approach and non-dominated sorting genetic algorithm II (NSGA-II), which is a multi-objective optimization algorithm. The objective was to design a cooling device that simultaneously achieves high cooling performance and low pressure drop since low pressure loss contributes to miniaturization and energy saving of the recirculating apparatus. The optimization result showed that pressure loss was reduced by 28.7% in comparison with the design variables determined through experiments without deteriorating the cooling performance.

Life-cycle reliability design optimization of high-power DC electromagnetic devices based on time-dependent non-probabilistic convex model process

The life-cycle reliability of high-power DC electromagnetic devices due to multi-source heterogeneous uncertainties in the design, manufacturing, loads, degradation and cumulative damages has become increasingly prominent, life-cycle reliability optimization has attracted extensive attention. The design optimization strategy based on reliability, which combines the static/time-independent hypothesis and random theory, is inapplicable to life-cycle design optimization. Therefore, a time-dependent uncertainty analysis and life-cycle quality reliability optimization method are proposed in this study. Based on the information entropy transformation method, the fuzzy uncertainty is transformed into a probability density function of equivalent random variables, and intervals for the random variables are determined in the standard normal space. In this way, the heterogeneous uncertainty is unified as an interval type. Moreover, the time-dependent characteristics of the uncertainty parameters are transformed into a time-dependent of the characteristics through ellipsoidal model process. A life-cycle expression method based on an orthonormal basis is proposed to form a life-cycle time-dependent non-probabilistic convex model process. Therefore, the analytical expression of out-crossing rate in which there are many non-probabilistic convex model process parameters are derived and the corresponding upper and lower bounds of out-crossing rate can be obtained. Then, a life-cycle reliability design optimization model is constructed and the optimal solution is determined from intelligence algorithm. The effectiveness of proposed method was verified by a high-power DC electromagnetic relay in renewable energy systems.

Graphic Procedure for the Optimum Design of Elastomeric Isolators

A simple graphic procedure for the optimum design of elastomeric seismic isolation devices is proposed. Starting from the design requirements concerning a base-isolated building, such as the device’s stiffness, maximum displacement, and vertical load, as well as the code checks on the device, the procedure allows defining the optimum values of the mechanical and geometrical parameters, such as rubber shear modulus, diameter, and thickness, and the number of rubber and steel layers. In more detail, the procedure allows for first identifying the ranges of the geometrical characteristics through a graphic representation of code checks in terms of the rubber’s diameter and volume, and then their specific values that allow one to obtain the optimum solution according to the design requirements for any fixed values of the mechanical characteristics of the materials. The graphic representation represents a suitable tool to better understand the role and influence of the different checks. The procedure can be easily automated by means of a computer code.

Month-long Respiratory Support by a Wearable Pumping Artificial Lung in an Ovine Model.

A wearable artificial lung could improve lung transplantation outcomes by easing implementation of physical rehabilitation during long-term pretransplant respiratory support. The Modular Extracorporeal Lung Assist System (ModELAS) is a compact pumping artificial lung currently under development. This study evaluated the long-term in vivo performance of the ModELAS during venovenous support in awake sheep. Feedback from early trials and computational fluid dynamic analysis guided device design optimization along the way. The ModELAS was connected to healthy sheep via a dual-lumen cannula in the jugular vein. Sheep were housed in a fixed-tether pen while wearing the device in a holster during support. Targeted blood flow rate and support duration were 2-2.5 L/min and 28-30 days, respectively. Anticoagulation was maintained via systemic heparin. Device pumping and gas exchange performance and hematologic indicators of sheep physiology were measured throughout support. Computational fluid dynamic-guided design modifications successfully decreased pump thrombogenicity from initial designs. For the optimized design, 4 of 5 trials advancing past early perioperative and cannula-related complications lasted the full month of support. Blood flow rate and CO2 removal in these trials were 2.1 ± 0.3 L/min and 139 ± 15 mL/min, respectively, and were stable during support. One trial ended after 22 days of support due to intradevice thrombosis. Support was well tolerated by the sheep with no signs of hemolysis or device-related organ impairment. These results demonstrate the ability of the ModELAS to provide safe month-long support without consistent deterioration of pumping or gas exchange capabilities.

Advanced architecture designs towards high-performance 3D microbatteries

Rechargeable microbatteries are important power supplies for microelectronic devices. Two essential targets for rechargeable microbatteries are high output energy and minimal footprint areas. In addition to the development of new high-performance electrode materials, the device configurations of microbatteries also play an important role in enhancing the output energy and miniaturizing the footprint area. To make a clear vision on the design principle of rechargeable microbatteries, we firstly summarize the typical configurations of microbatteries. The advantages of different configurations are thoroughly discussed from the aspects of fabrication technologies and material engineering. Towards the high energy output at a minimal footprint area, a revolutionary design for microbatteries is of great importance. In this perspective, we review the progress of fabricating microbatteries based on the rolled-up nanotechnology, a derivative origami technology. Finally, we discussed the challenges and perspectives in the device design and materials optimization.

Optimal Design of Electromagnetic Devices Assisted by Black Hole and Differential Evolution Algorithms

Recently, many design problems in the field of electrical engineering tend to be more complex, which are characterized by large scale in size, strong nonlinearity for performance analysis, and multi-dimensional design parameters. Therefore, it is not easy to seek for optimum effectively by traditional optimization algorithms. In order to solve optimal design of complex practical problems, in this paper, a novel hybrid optimization algorithm based on the differential evolution algorithm and the black hole theory is proposed and investigated. The differential evolution (DE) algorithm owns good diversity and flexibility, while the black-hole based optimization algorithm (BHBO) possesses faster convergence. In addition, these two algorithms have simple structures. The proposed algorithm with better merits combination may guarantee better convergence and stronger robustness than its independent counterparts of DE and BHBO. The searching performance is deeply investigated through numerical experiments on benchmark functions and practical electromagnetic applications.

Influence of soil-structure interaction (SSI) on optimal design of passive damping devices

Recently, the interest in research for optimization of viscous dampers in design of buildings has been increasing. In this study, the effect of soil-structure interaction has been taken into account for the purpose of optimal design of viscous dampers. A damper optimization method based on a target damping ratio and interstorey drift ratio found in literature has been adapted for a building structure model considering different types of sandy soils. While passive constraints have been taken as upper and lower limits of each damper, active constraints have been considered as a target damping ratio in terms of damping coefficients. The proposed algorithm includes time history analyses that test the designer’s optimal design. Interstorey drift ratios under design earthquakes have been checked at each design step. The first and second mode responses have been considered separately. According to the results obtained from this study, the negative impact of sandy soils on the dynamic behavior of superstructures can be overcome by optimal placement of dampers in buildings. The results of the analyses have shown that soil effects should be taken into account in solving damper optimization problems.

Homotopy perturbation method for Fangzhu oscillator

An accurate frequency-amplitude relationship is very needed to elucidate the properties of the oldest device of Fangzhu for collecting water from the air. The Fangzhu oscillator was derived and solved approximately (He et al. in Math Methods Appl Sci, 2020, https://doi.org/10.1002/mma.6384 ), here we show that the singular Duffing-like oscillator can be more effectively solved by the homotopy perturbation method and a criterion is obtained for the existence of a periodic solution for the singular differential equation. The results obtained in this paper are helpful for the optimal design of the Fangzhu device.

Electrochemical detection of ascorbic acid in artificial sweat using a\xa0flexible alginate/CuO-modified electrode

A flexible sensor is presented for electrochemical detection of ascorbic acid in sweat based on single-step modified gold microelectrodes. The modification consists of electrodeposition of alginate membrane with trapped CuO nanoparticles. The electrodes are fabricated at a thin polyimide support and the soft nature of the membrane can withstand mechanical stress beyond requirements for skin monitoring. After characterization of the membrane via optical and scanning electron microscopy and cyclic voltammetry, the oxidative properties of CuO are exploited toward ascorbic acid for amperometric measurement at micromolar levels in neutral buffer and acidic artificial sweat, at ultralow applied potential (− 5 mV vs. Au pseudo-reference electrode). Alternatively, measurement of the horizontal shift of redox peaks by cyclic voltammetry is also possible. Obtaining a limit of detection of 1.97 μM, sensitivity of 0.103 V log (μM)−1 of peak shift, and linear range of 10–150 μM, the effect of possible interfering species present in sweat is minimized, with no observable cross-reaction, thus maintaining a high degree of selectivity despite the absence of enzymes in the fabrication scheme. With a lateral flow approach for sample delivery, repeated measurements show recovery in few seconds, with relative standard deviation of about 20%, which can serve to detect increased loss or absence of vitamin, and yet be improved in future by optimized device designs. This sensor is envisioned as a promising component of wearable devices for e.g. non-invasive monitoring of micronutrient loss through sweat, comprising features of light weight, low cost, and easy fabrication needed for such application.Graphical Schematic depiction of the cyclic voltammetry signal change as the sweat flows over the sensor surface.

Biomechanical evaluation of internal fixation implants for femoral neck fractures: A comparative finite element analysis

Background and ObjectiveIt remains controversial regarding the optimal type of fixation implant for the treatment of femoral neck fractures (FNFs). Biomechanical rational for implant choices can benefit from the integration of finite element analysis (FEA) in device evaluation and design improvement. In this study, we aim to evaluate biomechanical performance of several internal fixation implants for Pauwels type III FNFs under physiological loading conditions using FEA, as well as to assess the biomechanical contribution of medial buttress plate (MBP) augmentation. MethodsSeveral fixation styles for FNFs have been analyzed numerically by the finite element method. Five groups of models were developed with different FNFs fixation implants, including dynamic hip screw (DHS), cannulated screws (CSs), proximal femoral nail antirotation (PFNA), DHS with MBP augmentation (DHS+MBP), and CSs with MBP (CSs+MBP). For each group, four FE models were established to evaluate strain in bone and stress in devices during walking and stair climbing conditions, which simulated the hip contact force using static and dynamic loadings respectively. ResultsNo notable differences were observed in peak strain within implanted bone and maximum stress values of the device between DHS and CSs. The implanted femur with PFNA was in a lower state of bone strain and implant stress. Although the buttress plate did not decrease peak bone strain, it alleviated stress concentration on device, especially for CSs under dynamic loadings. ConclusionsCompared to the other fixation styles, the PFNA showed biomechanical advantages of decreasing risk of implant failure and bone yielding. The MBP augmentation provided an additional load path to bridge fracture fragments, which reduced failure risk of DHS and CSs, especially during dynamic loading scenarios. Although further studies are needed for patients with other types of FNFs, our findings may provide valuable references for device design optimization in terms of complex physiological loadings, as well as for clinical decision making in surgical treatment of FNFs.

Experimental demonstration of dynamic thermal regulation using vanadium dioxide thin films

We present an experimental demonstration of passive, dynamic thermal regulation in a solid-state system with temperature-dependent thermal emissivity switching. We achieve this effect using a multilayered device, comprised of a vanadium dioxide (VO2) thin film on a silicon substrate with a gold back reflector. We experimentally characterize the optical properties of the VO2 film and use the results to optimize device design. Using a calibrated, transient calorimetry experiment we directly measure the temperature fluctuations arising from a time-varying heat load. Under laboratory conditions, we find that the device regulates temperature better than a constant emissivity sample. We use the experimental results to validate our thermal model, which can be used to predict device performance under the conditions of outer space. In this limit, thermal fluctuations are halved with reference to a constant-emissivity sample.

Design, Selection and Application of Energy Recovery Device in Seawater Desalination: A Review

In the seawater desalination system, the energy recovery system is a crucial part, as it consumes a lot of energy and plays a guiding role in the recovery efficiency. Therefore, in the energy recovery system, the recovery rate and energy consumption are the key factors to guide the system design. In order to make the energy recovery device achieve a high recovery rate under conditions of low energy consumption, the design and selection of each device in the system are particularly important. At the current stage, system matching optimization, device design optimization, and function objective optimization are widely used to improve the energy recovery system. In this paper, the design principle of the energy recovery integration system is analyzed, methods of reducing energy consumption and improving recovery efficiency are presented. The study provides guidance for the design and selection of energy recovery devices under different operating conditions.

Patient perspectives of ankle-foot orthoses for walking ability in peripheral artery disease: A qualitative study

Calf claudication associated with peripheral artery disease results in limited walking ability and diminished quality of life. Ankle-foot orthoses (AFO) have been used to mitigate calf pain during community-based walking exercise, yet little is known about patients' perspectives of this novel device. The purpose of this qualitative study was to determine the personal impact AFO had on patients who used them. Ten patients with calf claudication who previously completed a 12-week unstructured community-based walking program supplemented by AFO participated in a semi-structured recorded focus group. After data saturation was achieved, transcripts were coded and analyzed, and 2 primary themes emerged from the focus groups: 1) positive functional impact of AFO on walking ability and quality of life and 2) self-selected AFO usage patterns. Six subthemes included 1) positive ambulatory changes from using AFO, 2) sustained ambulatory improvements without AFO, 3) positive psychosocial impact, 4) optimal conditions for AFO usage, 5) optimal ambulatory surfaces when using AFO, and 6) challenges with comorbidities. The AFO were influential in decreasing claudication symptoms, improving walking capacity, and enhancing participation in meaningful daily and recreational activities. This study explores experiential knowledge of patients with calf claudication describing AFO as an effective tool to enhance unstructured walking programs. Further trials are needed to optimize device design and effectiveness in varying walking environments.

Dopant Concentration Controls Quasi-Static Electrostrictive Strain Response of Ceria Ceramics.

Electromechanically active ceramic materials, piezoelectrics and electrostrictors, provide the backbone of a variety of consumer technologies. Gd- and Sm-doped ceria are ion conducting ceramics, finding application in fuel cells, oxygen sensors, and, potentially, as memristor materials. While optimal design of ceria-based devices requires a thorough understanding of their mechanical and electromechanical properties, reports of systematic study of the effect of dopant concentration on the electromechanical behavior of ceria-based ceramics are lacking. Here we report the longitudinal electrostriction strain coefficient (M33) of dense RExCe1–xO2–x/2 (x ≤ 0.25) ceramic pellets, where RE = Gd or Sm, measured under ambient conditions as a function of dopant concentration within the frequency range f = 0.15–350 Hz and electric field amplitude E ≤ 0.5 MV/m. For >100 Hz, all ceramic pellets tested, independent of dopant concentration, exhibit longitudinal electrostriction strain coefficient with magnitude on the order of 10–18 m2/V2. The quasi-static (f < 1 Hz) electrostriction strain coefficient for undoped ceria is comparable in magnitude, while introducing 5 mol % Gd or 5 mol % Sm produces an increase in M33 by up to 2 orders of magnitude. For x ≤ 0.1 (Gd)–0.15 (Sm), the Debye-type relaxation time constant (τ) is in the range 60–300 ms. The inverse relationship between dopant concentration and quasi-static electrostrictive strain parallels the anelasticity and ionic conductivity of Gd- and Sm-doped ceria ceramics, indicating that electrostriction is partially governed by ordering of vacancies and changes in local symmetry.

Photo-Aligned Ferroelectric Liquid Crystal Devices with Novel Electro-Optic Characteristics

This paper examines different applications of ferroelectric liquid crystal devices based on photo-alignment. Successful application of the photo-alignment technique is considered to be a critical breakthrough. A variety of display and photonic devices with azo dye aligned ferroelectric liquid crystals is presented: smart glasses, liquid crystal Pancharatnam–Berry phase optical elements, 2D/3D switchable lenses, and laser therapy devices. Comparison of electro-optical behavior of ferroelectric liquid crystals is described considering the performance of devices. This paper facilitates the optimization of device design, and broadens the possible applications in the display and photonic area.

Oxidation Kinetics of WTe2 Surfaces in Different Environments

Tungsten ditelluride, WTe2, a layered transition metal dichalcogenide (TMD), displays superior physical and electronic properties and offers a fertile playground to study physics in low-dimensional materials with nontrivial band structures. However, WTe2 oxidizes in the air, leading to the formation of a surface oxide layer that introduces disorder and deteriorates electronic charge transport. This surface oxide, therefore, suppresses the intrinsic properties of WTe2 and can lead to the degradation of device performance. In this study, we report the formation of surface oxide and its kinetics in WTe2 single crystals through a combination of atomic force microscopy (AFM), Raman spectroscopy, and ellipsometry measurements. The measurements reveal nonuniform surface oxide dynamics, which upon saturation after several hours of atmospheric exposure yields a self-limiting approximately 2.5-nm-thick amorphous surface layer. In addition, in a controlled environment involving a continuous flow of nitrogen (N2), the formation of surface oxide is considerably impeded. These results offer insight into the surface degradation mechanisms of WTe2, which should be taken into account when striving for the optimal design and performance of WTe2-based devices.

Multi-Objective Analysis of a Fixed Solar Shading System in Different Climatic Areas

This study tackles the analysis of fixed external solar shading systems. The geometry of a building and of the shading system has been parametrically defined and a genetic optimization analysis has been carried out to identify an architectural solution that would allow the increase of energy savings, through a suitable window-to-wall ratio and an accurate design of the shading device. A multi-objective analysis has been performed with the aim of minimizing the energy consumption for space heating, cooling and artificial lighting, while ensuring the visual comfort of the occupants. The main goal of the study is to explore the influence of climatic context on the optimal design of shading devices. The analysis has been performed for three different latitudes across Europe. In all analyzed cases, a reduction of the annual energy consumption could be achieved, up to 42% if the optimal shading configuration is used. Moreover, the possibility of integrating the shading system with photovoltaic (PV) panels has been considered and the electricity production has been estimated.

Thickness-dependent carrier lifetime and mobility for MAPbBr3 single crystals

Carrier transfer is a key process for perovskite-based photoelectric conversion. It has a close relationship with grain boundaries, grain size, and contact layers. Understanding this relationship is of great significance for revealing the inherent characteristics of perovskite materials and for devices optimization. However, the dependence of carrier transfer characteristics (including carrier lifetime and mobility) on thickness is less studied, although which is a key issue for almost all perovskite material devices. Here we find that as the thickness of MAPbBr3 perovskite single crystal (PSC) increases from 1.47 μm to 10.55 μm, the carrier lifetime of MAPbBr3 decreases from 70 ns to 30 ns, and the carrier mobility decreases from 97 cm2 V−1 s−1 to 57 cm2 V−1 s−1, but they become constant in very thick samples. In addition, it was found that as the crystal thickness increased from 1.47 μm to 10.55 μm, the surface layer range gradually increased from 12 nm to 31 nm. The surface recombination velocity and surface defect (trap) density further confirmed that the thin PSC exhibited a small surface layer range. Finally, a three-layer carrier transmission model of PSC is proposed. This research provides guidance for the optimal design of PSC optoelectronic devices.

Integration of Interdigitated Electrodes in Split-Ring Resonator for Detecting Liquid Mixtures

A microwave microfluidic sensor for detecting binary liquid mixtures with a dielectric method at RF/microwave frequencies is presented in this article. The sensor is based on a split-ring resonator (SRR) that is implemented in a microstrip transmission line, with interdigitated electrodes (IDEs) being integrated into the ring for liquid detection. Based on the equivalent circuit of the IDE-SRR device and with a series of finite element simulations, the detection theory is developed, and the device design optimization is investigated. The validation measurements on water-isopropanol liquid mixtures with various concentrations show that the proposed IDE-SRR sensor has higher sensitivity than the previous standard SRR sensor. The IDE-SRR sensor is then used to detect two binary liquids, i.e., water-methanol mixtures and water-tetrahydrofuran mixtures. The measured effective permittivity results of the binary mixtures at RF/microwave frequency range are compared with the existing mixing models for binary dielectric mixtures at zero frequency.