Design Optimization Of Devices Research Articles

Reaction mechanism for atmospheric pressure plasma treatment of cysteine in solution

Mechanisms for the cold atmospheric plasma (CAP) treatment of cells in solution are needed for more optimum design of plasma devices for wound healing, cancer treatment, and bacterial inactivation. However, the complexity of organic molecules on cell membranes makes understanding mechanisms that result in modifications (i.e. oxidation) of such compounds difficult. As a surrogate to these systems, a reaction mechanism for the oxidation of cysteine in CAP activated water was developed and implemented in a 0-dimensional (plug-flow) global plasma chemistry model with the capability of addressing plasma-liquid interactions. Reaction rate coefficients for organic reactions in water were estimated based on available data in the literature or by analogy to gas-phase reactions. The mechanism was validated by comparison to experimental mass-spectrometry data for COST-jets sustained in He/O2, He/H2O and He/N2/O2 mixtures treating cysteine in water. Results from the model were used to determine the consequences of changing COST-jet operating parameters, such as distance from the substrate and inlet gas composition, on cysteine oxidation product formation. Results indicate that operating parameters can be adjusted to select for desired cysteine oxidation products, including nitrosylated products.

Linewidth narrowing for the distributed feedback nanoplasmonic laser

Ultra-narrow linewidth and single-mode output are vital for the further development of semiconductor nanolasers capable of excellent lasing performance. This paper addresses a systematic linewidth narrowing method for the design of a new type of nanoplasmonic laser coupled with distributed feedback (DFB) structure of nanogratings. Based on the physical model of DFB nanoplasmonic laser, the optical field distribution, carrier density distribution, relaxation oscillation and lasing spectra of the DFB laser were simulated with different parameters. The optimal device design for the DFB nanoplasmonic laser was achieved through a complete numerical simulation based on the multiple effects. By optimizing the influence of device parameters, the optimal structures for the DFB nanoplasmonic laser were achieved with the optimal optical properties of cavity mode, spectra and output power. The monochromatic DFB nanoplasmonic laser functions the optimum lasing performance with a single-mode peak at 514 nm, 3 dB linewidth of 0.1 pm, and the threshold current of 16 mA. This work provides a fundamental and technical support for the development of a new generation of efficient nanolaser devices with good spectra merits.

Requirements for design and function of blood pressure measuring devices used for the management of hypertension: Consensus Statement by the European Society of Hypertension Working Group on Blood Pressure Monitoring and Cardiovascular variability and STRIDE BP.

To develop scientific consensus recommendations for the optimal design and functions of different types of blood pressure (BP) measuring devices used in clinical practice for the detection, management, and long-term follow-up of hypertension. A scientific consensus meeting was performed by the European Society of Hypertension (ESH) Working Group on BP Monitoring and Cardiovascular Variability and STRIDE BP (Science and Technology for Regional Innovation and Development in Europe) during the 2022 Scientific Meeting of the ESH in Athens, Greece. Manufacturers were also invited to provide their feedback on BP device design and development. Thirty-one international experts in clinical hypertension and BP monitoring contributed to the development of consensus recommendations on the optimal design of BP devices. International consensus was reached on the requirements for the design and features of five types of BP monitors, including office (or clinic) BP monitors, ambulatory BP monitors, home BP monitors, home BP telemonitors, and kiosk BP monitors for public spaces. For each device type "essential" requirements (must have), and "optional" ones (may have) are presented, as well as additional comments on the optimal device design and features. These consensus recommendations aim at providing manufacturers of BP devices with the requirements that are considered mandatory, or optional, by clinical experts involved in the detection and management of hypertension. They are also directed to administrative healthcare personnel involved in the provision and purchase of BP devices so that they can recommend the most appropriate ones.

Theoretical modeling and experimental verification of an improved radial composite transducer consisting of a metal ring and a radially polarized piezoelectric stack

In the ring radial transducer, the wall thickness of the radially polarized piezoelectric ceramic is limited by the polarization technology and operating voltage, resulting in the limited power capacity and vibration ability of the transducer. Hence, an improved novel radial composite transducer (nRCT) is proposed in this paper, which consists of a radially polarized piezoelectric stack and a metal ring. Piezoelectric stack is used to enhance vibration and effectively solve the problem of difficult excitation caused by large wall thickness. A new electromechanical equivalent circuit model (EECM) of the nRCT in radial vibration is established, and the relationship between frequency characteristics of the nRCT and geometric size is analyzed. The finite element method (FEM) is used to carry out numerical modeling of the nRCT and the traditional radial composite transducer (tRCT), and preliminarily verify the calculation results of EECM. Compared with the tRCT, under the same electrical excitation, the equivalent electrical impedance of the nRCT designed in this paper decreases to 26%, and the radial vibration displacement increases to 142%. Finally, the nRCT and the tRCT are fabricated, and the experimental results have well verified the results of the theoretical analysis. The proposed radial piezoelectric stack model provides a new idea for the optimal design of radial vibration piezoelectric devices, which is expected to be further applied to the design of hydrophones, piezoelectric transformers, and medical ultrasound devices.

Gaussian doping profile in the channel region: A technology booster for junctionless transistors

In this work, we have developed analytical models for the channel potential, threshold voltage and drain current for a cylindrical Gate-All-Around Junctionless Metal-Oxide-Semiconductor Field Effect Transistors (GAA-JLTs) with Gaussian doped channel region along the radial direction with uniformly doped source and drain regions. It has been found that the variation in doping parameters, such as, straggle, projected range and peak doping concentration, significantly affects the device characteristics such as threshold voltage, Ion/Ioff and so on and therefore, tuning them may bring about optimized device design, avoiding excessive leakage current yet maintaining high on-state current. The results obtained through our proposed analytical model are validated by ATLAS 3-D device simulator. Further, the variation of channel potential with doping parameters and bias potentials have been investigated. We have shown that by tuning the doping profile parameters together with the aspect ratio (AR) of a non-circular cross-sectional JLT, the threshold voltage and Ion/Ioff can be optimized along with reduction in DIBL. The effects of Gaussian doping on few figures-of-merit (FOMs), as applicable to analog domain, have also been analyzed. Computations with necessary discussions have been presented to explore the impact of key doping parameters on the linearity of GAA-JL devices.

A Low-Noise Micromachined Accelerometer with Reconfigurable Electrodes for Resonance Suppression.

We present a high-performance capacitive accelerometer with a sub-µg noise limit and 1.2 kHz bandwidth for particle acceleration detection applications. The low noise of the accelerometer is achieved through a combination of device design optimization and operation under vacuum to reduce the effects of air damping. Operation under vacuum, however, causes amplification of signals around the resonance region, potentially resulting in incapacitating it through saturation of interface electronics or nonlinearities and even damage. The device has thus been designed with two sets of electrodes for high and low electrostatic coupling efficiency. During normal operation, the open-loop device utilizes its high-sensitivity electrodes to provide the best resolution. When a strong signal near resonance is detected, the electrodes with low sensitivity are used for signal monitoring, while the high-sensitivity electrodes are used to apply feedback signals efficiently. A closed-loop electrostatic feedback control architecture is designed to counteract the large displacements of the proof mass near resonance frequency. Therefore, the ability to reconfigure electrodes lets the device be used in high-sensitivity or high-resiliency modes. Several experiments were conducted with DC and AC excitation at different frequencies to verify the effectiveness of the control strategy. The results showed a ten-fold reduction of displacement at resonance in the closed-loop arrangement compared to the open-loop system with a quality factor of 120.

Software implementation of methods for optimal design of power electronic devices

The manuscript presents a software implementation of methods for the optimal design of power electronic devices based on MATLAB. Model-based optimization is one of the effective approaches to guarantee the performance of power electronic devices and systems. Through its application, the efficiency of the conversion of electrical energy is increased when setting a certain target function. Several examples are presented to demonstrate the effectiveness of the proposed optimization.

Zeta potential variations in bonding states of fluorocarbon films deposited by plasma-enhanced chemical vapor deposition

The interactions between a solid and a liquid at their interface often produce exotic effects that could be used in energy-related applications. To this end, understanding which properties control the zeta potentials at the interface promises to advance the application of these effects. In this study, we fabricated fluorocarbon films by plasma-enhanced CVD to investigate the interaction of the film with an aqueous solution. We found that the properties of the films can be controlled by the deposition pressure, and the zeta potential correlates with the bonding states within the films. The control of the interfacial potential between the solid material and the aqueous solution can be a factor in maximizing energy output and optimizing device design.

Navigational water resistance analysis and optimization of the gondola of unmanned boat retractable device

Combining the characteristics of the existing transfer slideway and double-point hanging type two retractable devices, this paper proposes a multiple-point hoisting, fast transfer, and retractable device. According to the viscous flow theory, one-way fluid-structure interaction simulation is used for the gondola structure of the unmanned boat retractable device. Considering the influencing factors of the width of the gondola, the void ratio, the shape and distribution of the void, and the deployment angle of the guardrail, the navigation water resistance of each model is compared and analyzed, and the optimal design of the gondola device is discussed. The results show that the increase of the top width and the decrease of the front-end void ratio will lead to an increase in the water resistance of the gondola; under the same porosity, the rectangular shape performs better than the circular shape, and the smaller interval between the rectangles is more conducive to reducing the water resistance of the gondola; the increase in the angle of the side door guardrail of the gondola will lead to an increase in the navigation water resistance; the final optimized design of the gondola device meets the strength requirements under extreme conditions of high sailing speed.

Study on Pulling Dynamic Characteristics of White Radish and the Optimal Design of a Harvesting Device

The loss rate is an important index to evaluate the harvesting performance of white radish. To reduce the loss rate, it is necessary to analyze the pulling dynamic characteristics of white radish and then optimize the structure and operating parameters of the harvesting device. In this paper, according to the growth characteristics of white radish in the field, the discrete element method (DEM) was used to simulate the pulling process. The pulling force was calculated using the Edinburgh elasto-plastic adhesion model (EEPA), and the effects of soil bed compactness, pulling speed and angle on the pulling force were analyzed. The tests on pulling mechanics were carried out in the laboratory to verify the accuracy of DEM simulation results. The results showed that in the soft soil bed with compactness less than 2.8 MPa, the pulling force of radish is generally smaller than the leaf breaking force, and it is feasible to pull the radish out directly. While in a soil bed with high compactness, it is necessary to install a loosening shovel to reduce the pulling force thus reducing the loss rate due to leaf breakage. The structure and operating parameters of the harvesting device were designed according to the pulling dynamic characteristics, and the white radish harvesting tests were carried out in different fields. Statistical results show that when the soil compaction was increased from 1.47 MPa to 2.21 MPa, the average loss rate increased from 0.68% to 1.75%, and the average damage rate increased from 2.41% to 2.70%. Similarly, when the forward speed was increased from 0.18 to 0.47 m/s, the average loss rate increased from 1.08% to 1.30%, and the average damage rate increased from 2.34% to 2.74%. Overall, the maximum loss rate and the maximum damage rate could be controlled below 2.0% and 3.0%, respectively. In the hard soil bed, the loss rate can be effectively reduced from 15% to 2.5% by installing a loosening shovel.

String-level compact modeling for dynamic operation and transient analysis of 3D charge trapping flash memory

In this article, we propose a string-level compact model, which is based on accurate and seamless channel electrostatic potential, for dynamic operation of 3D charge trapping flash (CTF) memory. First, we introduce a unit cell model for 3D CTF memory structure based on a conventional BSIM-CMG model using an extended netlist of equivalent circuits which describe the gate-all-around (GAA) structure composed of a metal gate, a blocking oxide, a charge trapping layer, and a tunneling oxide. Then, a string-level compact model is proposed, implying three advantages of inter-cell behaviors, seamless channel potential and process variation. To enhance the accuracy of the model behavior, extended model parameters are extracted showing good agreement with experimental data, such as I-V characteristics, program/erase speed, and incremental step pulse programming (ISPP). Furthermore, to predict channel electrostatic potential more precisely, we verify simulation program with integrated circuit emphasis (SPICE) simulation results of positively and negatively boosted channels comparing them with technology computer-aided design (TCAD) simulation results. Finally, we demonstrate that the proposed model can be efficiently applied to circuit simulation for analysis of the disturbance or failure mechanism and would equip the circuit designers and system architects with an effective tool for design optimization of 3D CTF memory devices.

Effect of enhancement in metal foam pore density on heat transfer of phase-change materials

To explore the effect of metal foam(MF)pore density on the melting and heat transfer of phase-change materials(PCMs), a semi-cylindrical visualization experimental setup was established to experimentally study copper MFs with different pore densities coupled with paraffin wax. The results showed that as pore density increases, the melting time of the composite PCMs decreases compared to that of pure paraffin wax by 11.5%, 16.2% and 18.1% for pore densities of 5, 20, and 30 PPI, respectively. Composite PCMs with a pore density of 30 PPI exhibited fastest melting and lowest maximum temperature difference during melting. Considering the relative thermal energy storage(TES) capacity and relative TES rate, composite PCMs with a pore density of 30 PPI exhibited optimal overall thermal storage performance. Furthermore, heat conduction was the primary means of thermal transmission during the melting of the bottom paraffin. However, the melting of the upper paraffin was nevertheless influenced by natural convection, Hence, as pore size decreased, the influence on the weakening of natural convection became more significant. The results of the study provide guidance for the optimal design of latent heat storage devices for semi-cylinders.

A Kernel-Free Boundary Integral Method for 2-D Magnetostatics Analysis

Performing magnetostatic analysis accurately and efficiently is very important for multi-objective optimization of electromagnetic device designs. In this research, a kernel-free boundary integral method (KFBIM) has been introduced for solving magnetic computations in a toroidal core geometry in 2-D. This study is very relevant in the design and optimization of toroidal inductors or transformers used in electrical systems, where lighter weight, higher inductance, higher efficiency, and lower leakage flux are required. The governing partial differential equations (PDEs) have been formulated as a system of the Fredholm integral equations of the second kind. Unlike traditional boundary integral methods or boundary element methods, KFBIM does not require an analytical form of Green’s function for evaluating integrals via numerical quadrature. Instead, KFBIM computes integrals by solving an equivalent interface problem on a Cartesian mesh. Compared with traditional finite difference methods for solving the governing PDEs directly, KFBIM produces a well-conditioned linear system. Therefore, the KFBIM requires only a fixed number of iterations when an iterative method [e.g., generalized minimal residual method (GMRES)] is applied for solving the linear system, and the numerical solution is not sensitive to computer round-off errors. The obtained results are then compared with a commercial finite element solver (ANSYS), which shows excellent agreement. It should be noted that, compared with FEM, the KFBIM does not require a body-fit mesh and can achieve high accuracy with a coarse mesh. In particular, the calculations of the magnetic potential and the tangential field intensity on the boundaries are more stable and exhibit almost no oscillations.

Thermodynamic limits and performance optimization of nighttime thermoradiative energy conversion systems with non-idealities

To address the challenge of the growing global energy crisis and the greenhouse effect, employing the thermoradiative effect of photodiodes to harvest radiative energy from colder outer space is considered a promising approach for direct nighttime renewable energy generation. By considering the coupled effect of the atmosphere, ambient, and non-radiative losses, a thermodynamic model of nighttime thermoradiative diodes (NTRDs) is developed. The fundamental performance limit for the achievable electric power density and device optimal designs of NTRDs are theoretically investigated based on Shockley-Queisser analysis. The modeling predicts that an ideal (nonideal) optimized NTRD can generate a maximum power density of 1.5 (0.12) mW/cm2 when operated at room temperature with an external luminescent efficiency of 100% (10%). The calculated results indicate that the maximal electric power generation of NTRDs is strongly influenced by the semiconductor bandgap and the external luminescent efficiency of the diode, as well as the ambient temperature and humidity. This work offers insights for optimal device designs of NTRDs, thus paving the way toward designing high-performance nighttime thermoradiative power generation systems.

Mechanical Analysis and Optimal Design of Wave Energy Device

At present, the global energy problem is serious. Wave energy is the kinetic energy and potential energy of waves on the ocean surface. Because of its high energy density, wide distribution, and long continuous operation of the device, it has become the focus of academic research. The key problem to be solved urgently for the large-scale application of wave energy is how to optimize the energy conversion efficiency of wave energy devices. This paper starts from the Newtonian dynamic equation, analyzes the motion state of the wave energy device in different wave environments, and studies the optimization and control of its power output. This paper first adopts the analysis method of first whole and then isolation, and establishes a one-dimensional coordinate system with the zero point of sea level. Then, the force analysis of the system is carried out, the dynamic differential equation is established, and the initial draft of the system is solved through the initial balance equation. Since the dynamic equation is a second-order linear ordinary differential inhomogeneous linear equation, the fourth-order Runge is used. The Kutta method is used to solve the problem, and the numerical solution for the position and velocity of the float is obtained. Secondly, the movable coordinate system is established with the float as the reference system, and the force analysis of the oscillator is carried out to obtain its relative dynamic equation. Then, the initial relative position of the oscillator is solved through the initial balance equation, and the relative dynamic differential equation is obtained by using the fourth-order Runge-Kutta method to obtain the numerical solution of the relative position and relative velocity of the oscillator with respect to time. Finally, the numerical solution of the absolute position and absolute velocity of the oscillator with respect to time is obtained through coordinate transformation.

Ultrafast hole relaxation dynamics in quantum dots revealed by two-dimensional electronic spectroscopy

Elucidating the population dynamics of correlated electron-hole pairs (bound excitons) in semiconducting quantum dots (QDs) is key for developing our fundamental understanding of nanoscale photophysics as well as for the optimal design of devices, such as lasers. For decades, it was assumed that holes did not contribute to band edge bleach signals in QDs. Here, we employ two-dimensional electronic spectroscopy to monitor electron and hole dynamics in both CdSe and CdSe/CdS/ZnS QDs to probe electron and hole dynamics. Based on a combination of time and frequency resolution, we observe a previously unresolved bleaching signal in CdSe QDs on timescales faster than 30 fs due to hole cooling. Atomistic semiempirical pseudopotential calculations are used to rationalize the order of magnitude difference in the observed hole dynamics in CdSe and CdSe/CdS/ZnS QDs. This picture advances our understanding of QD excitonics past the prevailing continuum effective mass theories generally used to describe QD electronic structure and dynamics.

Uncertainty quantification in inerter-based quasiperiodic lattices

Inerter-based periodic structures have attracted significant interest among the research community due to their wide range of applications. However, existing studies on quasiperiodic structures, especially with inerters, are limited. Therefore, this timely work investigates the dynamics of novel one-dimensional inerter-based quasiperiodic lattices with and without local resonators. The quasiperiodicity is introduced through the modulation of both spring and inerter properties resulting in the well-known Hofstadter-like butterfly spectrum having a fractal structure. Moreover, by considering the appropriate boundary conditions and many mass–spring-inerter subsystems, the bulk spectrum of the system is investigated demonstrating the existence of multiple edge states in lower and higher frequency ranges. The deterministic study showed that the effect of inertia amplification is to reduce the frequencies of the Hofstadter-like butterfly and to widen the low frequency band gaps. The second contribution of this work involves investigating the effect of parametric uncertainty for the acoustic-metamaterial-like chain based on Monte Carlo simulations. Moreover, to address the computational aspect of the problem, grey-box modeling using machine learning was performed. A Gaussian process model was trained on a limited dataset and was found to capture the stochastic responses of the lattices adequately. The statistical variation of parameters with different levels of uncertainty demonstrated significant effects on the Hofstadter-like butterfly, band gaps, corresponding edge states and frequency responses. The sensitivity of the dynamic behavior in quasiperiodic lattices to variabilities reveal the need to account for system uncertainties for their targeted performance as future vibration absorbers and energy harvesters. The study also paves the way to utilize the results as useful prior information for robust design optimization of real inerter-based quasiperiodic lattice devices.

Surface Effects on the Frequency Dispersion of Flexural Waves in Timoshenko Nanobeams

The surface effects play an important role in nanobeams. Based on a recently developed theory of surface elastodynamics, a model of the flexural wave propagation in Timoshenko nanobeams is established, in which the surface effects characterized by surface energy and surface inertia are introduced. It is found that when the size of a beam is comparable with nanometers, the surface energy effect would enhance the wave speed, while the surface inertial one would reduce it. An interesting phenomenon discovered is that with an increasing wave frequency, the dominant role transits from the surface energy effect to the surface inertial effect. The two kinds of surface effects exhibit a frequency-dependent competitive mechanism. In contrast to the macroscopic beams, due to the surface effects, the frequency dispersion of flexural waves in nanobeams becomes size-dependent. Furthermore, a comparison of the Timoshenko nanobeam and the Euler one indicates that the shear deformation effect and rotary inertial one cannot be neglected for a large wave number, which would prominently decrease the wave speed. Besides, when the size of the beam is large enough, the surface effects can be neglected and the present results can degenerate to the classical Timoshenko ones. The present results should be helpful not only for deep understanding of the dispersive mechanism of flexural waves in nanobeams, but also for optimal design of nanobeam-based acoustic wave devices.

Gate-voltage control of alternating-current-driven skyrmion propagation in ferromagnetic nanotrack devices

Magnetic skyrmions, with topologically protected particle-like magnetization configurations, are promising information carriers for future spintronics devices with ultralow energy consumption. Generally, during motion, skyrmions suffer from the skyrmion Hall effect (SkHE) wherein the skyrmions deflect away from the intended path of the driving force. Numerous methods have been proposed to avoid this detrimental effect. In this study, we propose controllable alternating current (AC)-driven skyrmion propagation in a ferromagnetic nanowire based on combination of gate-voltage-controlled magnetic anisotropy (VCMA) and SkHE. Micromagnetic simulations show that a skyrmion oscillatory closed-loop-like in situ motion driven by AC can be transformed into directional ratchet-like propagation along the nanotrack by creating a VCMA-gate barrier. Additionally, we show that the skyrmion propagation conditions depend on the gate barrier potential and driving AC parameters, and they can be used for the optimal design of nanotrack devices. Moreover, this mechanism could be used to control skyrmion macroscopic propagation directions by dynamically alternating the voltage of another series of gates. We further show the dynamic control of the long-distance propagation of skyrmions along with the pinning state. The study results provide a promising route for designing future skyrmion-based spintronics logical and memory devices.

Estimation of elastic modulus, fracture toughness and strength of 47.5B-derived bioactive glass-ceramics for bone scaffold applications: a nanoindentation study

The knowledge of the mechanical properties of glass–ceramic materials used in bone scaffolds is the key to the optimal design of tissue engineering devices. In this paper, the elastic properties and fracture toughness of silicate bioactive glass-ceramics based on the 47.5B parent composition were quantified for the first time through nanoindentation. Specifically, the effect of sintering temperature was investigated by testing samples sintered at six different temperatures. The samples sintered at higher temperatures exhibited elastic modulus and fracture toughness higher than those of the lower temperature samples. Both properties are comparable with those shown by similar bioactive glasses available in literature, supporting the mechanical suitability of the materials for bone applications. An estimation of tensile strength as a function of flaw size is also provided by means of fracture mechanics approaches.