Design Optimization Of Devices Research Articles

Developing multi-objective optimization model with conflicting goals to improve the surge protection devices design for water hammer

In this study, a Multi-objective Optimization Model (MOM) is developed and solved for the optimum design of surge protection devices (including air chamber and shock damper) with conflicting goals. The shock damper is a new type of surge tank invented by researchers. For the first time, the design parameters of the shock damper as decision variables are raised in a MOM problem, and results are benchmarked with solving the model for the air chamber as well. Method of characteristics (MOC) is chosen for the numerical solution of water hammer PDE’s and its system of equations for interior and boundary nodes are used as constraints of the optimization model. The conflicting criteria of the MOM are functions of safety in the system and installation cost of protection devices. In the following by using the weight coefficients and normalized objective functions obtained by dividing each of the mentioned functions by the maximum potential values of them, the resulting problem is solved by Genetic Algorithm (GA). The results, while investigated conceptually, show the significant improvement of multi-objective design in the performance and cost-saving in protection devices and the better function of shock damper regarding both criteria.

눈의 열물성치에 따른 철도 분기부 발열장치의 융설 특성 해석

It is very important to analyze the snow melting performance and optimal design of heating devices for stable operation of railway turnouts in winter snow situations. However, in previous research, heating devices themselves were the focus, without consideration of snow melting characteristics. In this paper, to analyze the snow melting characteristics of a heating device under snow-covered conditions, thermal analysis was performed considering phase change. In addition, since the thermal properties of snow can change sensitively according to snow-density, the snow melting characteristics of the heating device were analyzed for three types of snow-density. As a result of analyzing the snow melting characteristics, it was confirmed that the lower the snow density, the wider the snow melting range and the higher the maximum temperature of the heating device. From this, it can be inferred that, for identical snow cover heights, the performance of the heating device deteriorates in wet snow conditions with high density.

Failure Physics and Reliability of GaN‐Based HEMTs for Microwave and Millimeter‐Wave Applications: A Review of Consolidated Data and Recent Results

Herein, the results are reviewed concerning reliability of high‐electron mobility transistors (HEMTs) based on GaN, which currently represent the technology of choice for high‐efficiency microwave and millimeter‐wave power amplifiers. Several failure mechanisms of these devices are extensively studied, including converse piezoelectric effects, formation of conductive percolation paths at the edge of gate toward the drain, surface oxidation of GaN, time‐dependent breakdown of GaN buffer, and of field‐plate dielectric. For GaN HEMTs with scaled gate length, the simultaneous control of short‐channel effects, deep‐level dispersion, and hot‐electron‐induced degradation requires a careful optimization of epitaxial material quality and device design.

Optimal design of cubic nonlinear energy harvester device for random vibrations

Linear energy harvesters have a narrow frequency bandwidth and hence operate efficiently only when the excitation frequency is very close to the fundamental frequency of the harvester. Consequently, small variations of the excitation frequency around the harvester’s fundamental frequency drop the energy output making the harvesting process inefficient. To extend the harvester’s bandwidth, some recent solutions call for using electromechanical devices with stiffness-type nonlinearities. This work deals with the optimisation of the performance of a single degree-of-freedom electromagnetic energy harvester whose mechanical behaviour has a Duffing-type nonlinearity, as for suspended masses, to reduce the size of energy harvesting devices without affecting their power output. The vibration input is assumed as a broadband Gaussian white noise base acceleration. It is analytically shown that the optimum load resistance of the device is different to that which is dictated by the principle of impedance matching.

Coated Blade Spray with a Barrier: Improving Negative Electrospray Ionization and Sample Preparation.

Substrate-based electrospray ionization (ESI) techniques like paper, wooden tip, plastic tip, and metal-needle-based spray suffer from corona discharge, high background noise, and unstable spray in negative ionization mode, especially for the analysis of complex biological matrices, such as blood and urine. Coated blade spray coupled with mass spectrometry (CBS-MS) combines solid-phase microextraction's (SPME) efficient sample clean-up and enrichment and ambient MS's fast analysis and has proven to be an appealing alternative tool for the fast screening of target analytes in complex matrices. This paper documents the development of a new CBS blade design that features a barrier at the far end of the ESI tip. The findings of this work show that the addition of this simple barrier enabled the total RSD% to be reduced to less than 10% for sample preparation, ionization, and the MS detection of several drugs of abuse in negative mode, without compensation using internal standards. The improved stability of ESI in negative mode was investigated by observing the ESI process with a microscope camera and testing via CBS-MS. The new design was applied for the analysis of three drugs of abuse in urine, with the calibration curve correlation coefficient (R2 ≥ 0.9997) being calculated without the use of internal standards. The overall RSD% of the peak area for one compound in 42 samples was 6.9%, which highlights the method's incredible reproducibility compared to other ambient MS techniques for analyzing real samples. The CBS device with a barrier was also applied for the on-blade sampling of 14 drugs of abuse in 20 μL of plasma spot in positive ionization mode. The results of these tests yielded a calibration curve correlation coefficient of R2 ≥ 0.9883 and limits of quantification (LOQs) between 0.25 and 25 ng/mL. The obtained results provide guidance on CBS device design optimization and the effective automation of the protocol.

Optimal Design of Optical Waveguide Devices Utilizing Beam Propagation Method with ADI Scheme

Optimal Design of Optical Waveguide Devices Utilizing Beam Propagation Method with ADI Scheme

Topology Optimal Design of NRD Guide Devices Using Function Expansion Method and Evolutionary Approaches

In order to increase communication capacity, the use of millimeter-wave and terahertz-wave bands are being actively explored. Non-radiative dielectric waveguide known as NRD guide is one of promising platform of millimeter-wave integrated circuits thanks to its non-radiative and low loss nature. In order to develop millimeter wave circuits with various functions, various circuit components have to be efficiently designed to meet requirements from application side. In this paper, for efficient design of NRD guide devices, we develop a topology optimal design technique based on function-expansion-method which can express arbitrary structure with arbitrary geometric topology. In the present approach, recently developed two-dimensional full-vectorial finite element method (2D-FVFEM) for NRD guide devices is employed to improve computational efficiency and several evolutionary approaches, which do not require appropriate initial structure depending on a given design problem, are used to optimize design variables, thus, NRD guide devices having desired functions are efficiently obtained without requiring designer's special knowledge.

Towards sustainability with self-healing and recyclable perovskite solar cells

Lead halide perovskite solar cells (PSCs) have been considered one of the most promising candidates for future energy supply, whereas just solar cell does not guarantee sustainability. Owing to the ionic nature and constituent heavy metals, perovskite materials are prone to decay under operating conditions and pose a threat to ecosystems and human health, seriously restricting their practical deployment. Herein, we briefly review safe-by-design strategies to heal failed PSCs and thereby extend their operational lifetime and to recycle lead perovskites at the end of their lifespan for cyclic utilization. From the point of view of processability, scalability, and universality, we recommend future approaches for the further development of PSCs towards sustainable photovoltaics, taking into consideration materials selection, device design, and process optimization.

Optimizing phase change composite thermal energy storage using the thermal Ragone framework

Optimal design of thermal energy storage devices can allow systems to approach specific design objectives while maintaining desired levels of performance. The thermal Ragone framework has been applied to the design of thermal energy storage heat exchangers, specifically identifying relationships between their power and energy capabilities. In this paper, a finite-difference model is used to optimize thermal storage heat exchanger designs for three objectives given a discharge power constraint. The three objectives are maximizing energy density, minimizing energy-specific capital costs, and minimizing the levelized cost of storage. This study focuses on the design of planar thermal energy storage heat exchangers with phase change materials and thermal conductivity additives. Key design parameters identified included the conductivity additive volume fraction, spacing between heat transfer fluid tubes, and the phase transition temperature. The optimal design is found to depend strongly on the required thermal power, with higher powers requiring transition temperatures further from the use temperature, more conductivity additives, and closer tube spacing. There is also a trade-off between these design parameters, where changing one (e.g., closer tube spacing) can allow another parameter to be relaxed (e.g., less conductivity additive). To aid in future device design, models of reduced complexity were developed and evaluated for their ability to predict optimal designs. These simplified models can predict the performance of thermal energy storage heat exchangers up to 5000 times faster than the finite-difference model. For the design objectives of maximizing energy density, minimizing costs, and minimizing levelized cost of storage, the simplified models predicted optimal designs with average absolute deviations below 2 % in relation to the optimal designs chosen by the finite difference model optimization. These models can serve as tools to further study thermal storage heat exchangers incorporating the realistic trade-off between the device's power and energy.

Physics-Informed Generative Adversarial Network-Based Modeling and Simulation of Linear Electric Machines

The demand for fast magnetic field approximation for the optimal design of electromagnetic devices is urgent nowadays. However, due to the lack of a publicly available dataset and the unclear definition of each parameter in the magnetic field dataset, the expansion of data-driven magnetic field approximation is severely limited. This study presents a physics-informed generative adversarial network (PIGAN), as well as a permanent magnet linear synchronous motor (PMLSM)-based magnetic field dataset, for fast magnetic field approximation. It includes the current density, material distribution, electromagnetic material properties, and other parameters of the electric machine. Physics-informed loss functions are utilized in the training process, making the output governed by Maxwell’s equation. Different slot-pole combinations of the PMLSM are involved in the dataset to extend the generalization of PIGAN. Some indicators for the further evaluation of magnetic approximation performance, including image-based metrics and calculation methods for the performance of electric motors, are presented in this study. Some challenges of magnetic field approximation using PIGAN are also discussed. The effectiveness of the physics-informed method is verified by comparing the magnetic field approximation results and the performance analysis results of the PMLSM with FEM, and the speed of PIGAN is approximately 40 times faster than that of FEM, while the accuracy is similar.

Multi-Objective Optimization of a Heat Sink for the Thermal Management of a Peltier-Cell-Based Biomedical Refrigerator

Both storage and transport of medical products remains a challenging task because of many variables as well as infrastructures, territory, and so on. Among these variables, monitoring the medical products temperature is fundamental to guarantee their safety. On the other hand, for sectors like aerospace delivery, weight has a crucial role too. For such applications and especially for strongly variable external temperatures, Peltier cells might be employed for either cooling or heating medical products to be stored. Accordingly, this study addresses the optimization of a heat sink for the thermal management of a Peltier-cell-based biomedical refrigerator. In detail, a brute-force multi-objective optimization of an impinging-flow finned heat sink for the Peltier cell is carried out here. Thermal resistance, weight, and pressure drop are chosen as the three-objective functions to be minimized, with both geometrical and volumetric flow rate as design variables. The results present a very large bunch of optimal solutions to design such devices. With the utopia optimum criterion, Rth = 0.159 °C/W, msink = 0.550 kg, and Δp = 14.99 Pa are obtained. Finally, both multiple-linear regression and artificial neural networks are employed to relate design variables with the objective functions, in order to provide the final user with a practical tool for the optimal design of such devices.

On interaction between fatigue of reconstruction plate and time-dependent bone remodeling

Background and objectiveThe fibula free flap (FFF) has been extensively used to repair large segmental bone defects in the maxillofacial region. The reconstruction plate plays a key role in maintaining stability and load-sharing while the fibula unites with adjacent bone in the course of healing and remodeling. However, not all fibula flaps would fully unite, and fatigue of prosthetic devices has been recognized as one major concern for long-term load-bearing applications. This study aims to develop a numerical approach for predicting the fatigue life of the reconstruction plate by taking into account the effect of ongoing bone remodeling. MethodsThe patient-specific mandible reconstruction with a prosthetic system is studied in this work. The 3D finite element model with heterogeneous material properties obtained from clinical computerized tomography (CT) data is developed for bone, and eXtended Finite Element Method (XFEM) is adopted for the fatigue analysis of the plate. During the remodeling process, the changing apparent density and Young's modulus of bone are simulated in a step-wise fashion on the basis of Wolff's law, which is correlated with the specific clinical follow-up. The maximum biting forces were considered as the driving force on the bone remodeling, which are measured clinically at different time points (4, 16 and 28 months) after reconstruction surgery. ResultsUnder various occlusal loadings, the interaction between fatigue crack growth and bone remodeling is investigated to gain new insights for the future design of prosthetic devices. The simulation results reveal that appropriate remodeling of grafted bone could extend the fatigue life of fixation plates in a positive way. On the other hand, the rising occlusal load associated with healing and remodeling could lead to fatigue fracture of fixation plate and potentially cause severe bone resorption. ConclusionThis study proposes an effective approach for more realistically predicting fatigue life of prosthetic devices subject to a tissue remodeling condition in-silico. It is anticipated to provide a guideline for deriving an optimal design of patient-specific prosthetic devices to better ensure longevity.

Relationship of shading devices and its effects on daylight in Commercial buildings in Pune

Day lighting is a critical part of visual environment in workspaces. It creates a sense of well-being and contributes to the efficiency of the occupants. Research has established that solar radiation admitted through the windows have serious effects on visual comfort of the occupants in the indoor spaces. Use of solar shading devices can address glare problems. This signifies the need for design of optimal shading devices that increase daylight levels with desirable control on excessive sunlight with an aim to reduce glare and discomfort for the occupants. In this research various configurations of conventional shading devices used for commercial buildings located in Pune, India was examined. A typical commercial building is modelled using the simulation program Integrated Environmental Solutions (IES) where existing as well as different identified configuration of shading devices was analysed for daylight performance and visual comfort with respect to amount and uniformity of illumination with Radiance rendering tool. The analysis indicated that use of appropriate shading device result in improved visual comfort for occupants. The performance of different shading device presented aimed to help architects to select suitable shading device in order to contribute to sustainability aspects of office buildings in warm and humid climatic regions.

S1106 Analysis of Reported Adverse Events Related to Over the Scope Clips: A MAUDE Database Analysis

Introduction: Over-the-scope clips (OTSC) have been increasingly used in the management of bleeding, perforations, fistulae, and anastomotic leaks in the gastrointestinal tract. However, since their Food and Drug Administration (FDA) approval in 2010, data on the adverse events of OTSC systems has been lacking. Our study aims to report and analyze adverse events and device failures associated with OTSC systems using the FDA’s Manufacturer and User Facility Device Experience (MAUDE) database. Methods: We analyzed the post-marketing surveillance data from the FDA MAUDE database of the two OTSC systems available in the United States: The Padlock clip system and the Ovesco OTSC from April 2017 through May 2022. Results: Thirty-six medical device reporting claims were found from May 2017 through May 2022. Adverse events were classified as device-related problems and patient-related adverse events. Thirty-six device-related problems were reported, along with sixteen device-related adverse events (Table). Most device-related problems were reported in the Padlock defect closure system (n=23), followed by the Padlock pro clip system (n=8) and Ovesco OTSC clip system (n=5). The most common device-related problem was related to the failure of deployment of OTSC (n=14), followed by material protrusion or extrusion (n=6). The most common patient adverse events were perforation (n=4), bleeding (n=3), esophageal laceration (n=3) and luminal stenosis (n=2). Three out of four perforations were in the Padlock pro select closure system. All four patients required surgical management of the perforation. No deaths related to the use of OTSC were reported. Conclusion: Using the data from a publicly available database, the overall adverse events from OTSC systems remain low. Failure of OTSC deployment and perforation were the most common device-related problem and patient-related adverse events, respectively. The identification of common adverse events has the potential to optimize device design and patient outcomes. It is important for endoscopists to be mindful of these potential adverse events when using over-the-scope clips. Table 1. - Device-related problems and adverse events Device-related problems Number Failure of OTSC deployment 14 Other 8 Separation problems 3 Detachment of the device 2 Protrusion or extrusion of over the scope clip system 6 Defective device component 2 Failure of positioning of the device 1 Total 36 Patient related- adverse events Number Gastro-gastric fistula 1 Perforation 4 Local trauma 1 Pain 1 Bleeding 3 Pyloric stenosis 1 Colonic stenosis 1 Esophageal laceration 3 Ulcer 1 Total 16

Meta-Optics-Empowered Switchable Integrated Mode Converter Based on the Adjoint Method.

Monolithic integrated mode converters with high integration are essential to photonic integrated circuits (PICs), and they are widely used in next-generation optical communications and complex quantum systems. It is expected that PICs will become more miniaturized, multifunctional, and intelligent with the development of micro/nano-technology. The increase in design space makes it difficult to realize high-performance device design based on traditional parameter sweeping or heuristic design, especially in the optimal design of reconfigurable PIC devices. Combining the mode coupling theory and adjoint calculation method, we proposed a design method for a switchable mode converter. The device could realize the transmission of TE0 mode and the conversion from TE0 to TE1 mode with a footprint of 0.9 × 7.5 μm2 based on the phase change materials (PCMs). We also found that the mode purity could reach 78.2% in both states at the working wavelength of 1.55 μm. The designed method will provide a new impetus for programmable photonic integrated devices and find broad application prospects in communication, optical neural networks, and sensing.

Enhanced performance of magnetoelectric voltage coefficient in giant magnetostrictive (Ni0.7Mg0.3Fe2O4)/piezoelectric (BaZr0.2Ti0.8O3) composites

The non-toxic lead-free multiferroic composite samples Ni0.7Mg0.3Fe2O4/BaZr0.2Ti0.8O3 were synthesized by using standard double sintering ceramic method. The composite samples are found to exhibit dielectric response, which might be associated with Maxwell-Wagner type interfacial polarization and Koop's phenomenological theory. The variation of DC conductivity with respect to temperature revealed the conduction of electrons i.e. due to the small polarons hopping mechanism. The synthesized ME composite samples show a representative magnetic hysteresis (M − H) loop type behaviour at room temperature. In a previous report, the response of ME voltage coefficient 4.262 mVcm-1.Oe was determined for (30%) Ni0.8Mg0.2Fe2O4 + (70%) BaZr0.2Ti0.8O3 composites at 5.0 kOe applied DC magnetic field. But in this report, we improved the ME voltage coefficient for the composition 50% (Ni0.7Mg0.3Fe2O4) + 50% (BaZr0.2Ti0.8O3) which is a lead-free ME composite with the massive ME voltage coefficient of 8.562 mV/cm.Oe was achieved. Hence, the estimated results can provide experimental guidance for the optimal design of high-performance magnetoelectric devices and render better support for the technological development in the field of magnetoelectricity.

Identification of Analytical Singularity in a Non‐Plasmonic Nanosensing System

AbstractOptical sensing works most efficiently around the singularity of resonances. In the pursuit of high quality‐factor and sensitivity, non‐plasmonic nanosensors are desired as metallic materials are intrinsically lossy. However, standalone resonant systems of dielectric nanoparticles (NPs) generally do not possess a pole or its identification has proven to be hard across the complex frequency domain. To solve this problem, an active external cavity is designed and the dielectric NP is put inside it to formulate a cavity‐NP (C‐NP) system. The dielectric NP has dimensions comparable with the effective wavelength in the particle material and the coupled resonance is shown to exhibit a pole when a singular optimum gain is applied, overcoming the no‐pole‐limitation of dielectric NPs. The underlying physics of the coupled system is studied with the pseudo‐orthonormal eigenmode method (POEM), which can treat such non‐Hermitian systems and quickly pinpoint the singularity from the real frequencies. The POEM study generates a set of guidelines that facilitate device design and experimental optimization. Through dynamic finite‐difference time‐domain simulations, the all‐dielectric gain‐assisted cavity‐NP structure thus identified is shown to reach a pole at small optical gain. When used as a sensor, the system accommodates nanoscale sensing volume and giant sensitivity when operated around its pole.

Optical characterisation of dyed liquid crystal cells

ABSTRACT The guest-host liquid crystal display, first proposed in 1968, relies on controlling the orientation of dichroic dyes dissolved in a nematic liquid crystal host. Controlling the orientation of the liquid crystal and of the dissolved dye with an electric field allows control of the transmittance of the cell. Knowing the dielectric properties at optical frequencies of the dye and liquid crystal mixtures is crucial for the optimal design of guest-host liquid crystal devices. In this work, the dielectric functions of various layers in liquid crystal cells are described by models obeying the Kramers-Kronig relations: the Sellmeier equation for transparent layers and the causal Gaussian oscillator model for absorbing layers. We propose a systematic way to accurately model the dielectric response of each layer by minimising the sum of squared differences between the measured transmittance spectrum of a guest-host cell in the near-UV/vis range and the prediction of the transmittance of the modelled multilayer structure. By measuring the transmittance for incident light polarised parallel and perpendicular to the nematic director allows us to separately characterise the two principal dielectric functions of the uniaxial sample. Our results show that the causal Gaussian oscillator model can accurately characterise the dielectric functions of dyes in liquid crystals.

Analysis and evaluation of Si(1-x) Ge(x) pocket on sensitivity of a dual-material double-gate dopingless tunnel FET label-free biosensor

This work reports a sensitivity analysis for a dual-material double-gate dopingless Tunnel FET (DM-DG-DLTFET) biosensor carrying a Si(1-x) Ge(x) pocket for improved performance of an overall device. The biomolecules are immobilized in a cavity suitable for small-sized biomolecules detection and the performance of the device is investigated by calculating the electrical properties altered due to the dielectric modulation caused by presence and absence of biomolecules by commercially available ATLASTM tool. The Si(1-x) Ge(x) pocket placed under the cavity at source-channel interface helps to attain better on-current which is usually less in case of other reported structures of Tunnel FETs. The variation in the composition of Ge is observed to obtain enhanced sensitivity. The device is studied for threshold voltage sensitivity of neutral as well as charged biomolecules and the nature of the present biomolecule is also determined using the transconductance-to-current ratio (gm/Ids) which can also be considered as a sensing metric. The optimized device design has been proposed keeping track of the electrical and physical trade-offs. Our results show a maximum of 539.5 mV shift in the threshold voltage when dielectric constant (K) of the neutral biomolecule is varied from 1 to 12 which makes our device evidently an efficient candidate for label-free biosensing application.

Optimal design of loading device based on a redundantly actuated parallel manipulator

Reliability of machine tools has attracted much attention both in academia and industry. The loading device is very important for the reliability study of CNC machine tools as it can apply multi-axis dynamic forces to the spindle to replace cutting tests. A loading device based on the redundantly actuated parallel manipulator (R5LD) with strong loading capability is proposed in this paper. Firstly, to evaluate the loading capability, this paper proposes new transmission indices for redundantly actuated parallel manipulators (PMs). Besides, the prescribed flexible orientation workspace and regular workspace are defined for the loading device. Then, the corresponding performance atlases are represented graphically in the design space. The structure parameters of the R5LD are achieved in the optimum region of performance atlases. Finally, the R5LD with the optimum parameters is compared with the loading device based on the corresponding non-redundant PM. The R5LD has a larger regular workspace and better transmission performance. The additional UPS chain of the R5LD makes the configuration more symmetrical, balances forces distribution among chains, and strengthens the loading capability of the loading device.