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1.
J Chem Phys ; 157(10): 104109, 2022 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-36109219

RESUMO

This study extends the accurate and transferable molecular-orbital-based machine learning (MOB-ML) approach to modeling the contribution of electron correlation to dipole moments at the cost of Hartree-Fock computations. A MOB pairwise decomposition of the correlation part of the dipole moment is applied, and these pair dipole moments could be further regressed as a universal function of MOs. The dipole MOB features consist of the energy MOB features and their responses to electric fields. An interpretable and rotationally equivariant derivative kernel for Gaussian process regression (GPR) is introduced to learn the dipole moment more efficiently. The proposed problem setup, feature design, and ML algorithm are shown to provide highly accurate models for both dipole moments and energies on water and 14 small molecules. To demonstrate the ability of MOB-ML to function as generalized density-matrix functionals for molecular dipole moments and energies of organic molecules, we further apply the proposed MOB-ML approach to train and test the molecules from the QM9 dataset. The application of local scalable GPR with Gaussian mixture model unsupervised clustering GPR scales up MOB-ML to a large-data regime while retaining the prediction accuracy. In addition, compared with the literature results, MOB-ML provides the best test mean absolute errors of 4.21 mD and 0.045 kcal/mol for dipole moment and energy models, respectively, when training on 110 000 QM9 molecules. The excellent transferability of the resulting QM9 models is also illustrated by the accurate predictions for four different series of peptides.


Assuntos
Elétrons , Aprendizado de Máquina , Eletricidade , Distribuição Normal , Água
2.
Science ; 377(6612): 1244-1245, 2022 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-36108028

RESUMO

Supercomputing and accelerator centers struggle with surging gas and electricity prices.


Assuntos
Eletricidade , Europa (Continente)
3.
Phys Rev Lett ; 129(10): 103201, 2022 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-36112446

RESUMO

Enantiodetection of chiral molecules is important to chemical reaction control and biological function designs. Traditional optical methods of enantiodetection rely on the weak magnetic-dipole or electric-quadrupole interactions, and in turn suffer from the weak signal and low sensitivity. We propose a new optical enantiodetection method to determine the enantiomeric excess via two-dimensional (2D) spectroscopy of the chiral mixture driven by three electromagnetic fields. The quantities of left- and right-handed chiral molecules are reflected by the intensities of different peaks on the 2D spectrum, separated by the chirality-dependent frequency shifts resulting from the relative strong electric-dipole interactions between the chiral molecules and the driving fields. Thus, the enantiomeric excess can be determined via the intensity ratio of the peaks for the two enantiomers.


Assuntos
Eletricidade , Campos Eletromagnéticos , Magnetismo , Análise Espectral , Estereoisomerismo
4.
Comput Intell Neurosci ; 2022: 9635251, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36105635

RESUMO

With the development of science and technology, the rapid development of social economy, the motor as a new type of transmission equipment, in the production and life of people occupies a pivotal position. Under the rapid development of computer and electronic technology, manufacturing equipment is becoming larger, faster, more continuous, and more automated. This has resulted in complex, expensive, accident-damaging, and high-impact equipment for electric motors; even routine maintenance requires significant equipment maintenance and maintenance costs. If a fault occurs, it will cause serious damage to the entire equipment and can even have a major impact on the entire production process, leading to a serious economic and social life. In this paper, a CNN-based machine learning fault diagnosis method is proposed to address the problem of high incidence of motor faults and difficulty in identifying fault types. A fault reproduction test is constructed by machine learning techniques to extract vibration time domain data for normal operating conditions, rotor eccentricity, stator short circuit, and bearing inner ring fault; divide the data segment into 15 speed segments, extract 13 typical time domain features for each speed segment; and perform mathematical statistics for fault diagnosis. Compared with the traditional algorithm, the method has more comprehensive feature information extraction, higher diagnostic accuracy, and faster diagnostic speed, with a fault diagnosis accuracy of 98.7%.


Assuntos
Algoritmos , Aprendizado de Máquina , Eletricidade , Eletrônica , Humanos , Armazenamento e Recuperação da Informação
5.
Int J Mol Sci ; 23(17)2022 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-36077154

RESUMO

The paper reports a strategy to synthesize Cd0.9Co0.1S nanorods (NRs) via a one-pot solvothermal method. Remarkably, the pencil-shaped Cd0.9Co0.1S NRs with a large aspect ratio and good polycrystalline plane structure significantly shorten the photogenerated carrier transfer path and achieve fast separation. An appropriate amount of Co addition enhances visible light-harvesting and generates a photothermal effect to improve the surface reaction kinetics and increases the charge transfer rate. Moreover, the internal electric field facilitates the separation and transfer of carriers and effectively impedes their recombination. As a result, the optimized Cd0.9Co0.1S NRs yield a remarkable H2 evolution rate of 8.009 mmol·g-1·h-1, which is approximately 7.2 times higher than that of pristine CdS. This work improves the photocatalytic hydrogen production rate by tuning and optimizing electronic structures through element addition and using the photothermal synergistic effect.


Assuntos
Compostos de Cádmio , Nanotubos , Cádmio , Compostos de Cádmio/química , Eletricidade , Luz , Nanotubos/química
6.
Sensors (Basel) ; 22(17)2022 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-36080880

RESUMO

Two problems arise when using commercially available electric liquid mosquito repellents. First, prallethrine, the main component of the liquid repellent, can have an adverse effect on the human body with extended exposure. Second, electricity is wasted when no mosquitoes are present. To solve these problems, a TinyML-oriented mosquito sound classification model is developed and integrated with a commercial electric liquid repellent device. Based on a convolutional neural network (CNN), the classification model can control the prallethrine vaporizer to turn on only when there are mosquitoes. As a consequence, the repellent user can avoid inhaling unnecessarily large amounts of the chemical, with the added benefit of dramatically reduced energy consumption by the repellent device.


Assuntos
Repelentes de Insetos , Fenômenos Fisiológicos , Eletricidade , Humanos
7.
Sensors (Basel) ; 22(17)2022 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-36080888

RESUMO

This paper presents a fully integrated high-voltage (HV) neural stimulator with on-chip HV generation. It consists of a neural stimulator front-end that delivers stimulation currents up to 2.08 mA with 5 bits resolution and a switched-capacitor DC-DC converter that generates a programmable voltage supply from 4.2 V to 13.2 V with 4 bits resolution. The solution was designed and fabricated in a standard 180 nm 1.8 V/3.3 V CMOS process and occupied an active area of 2.34 mm2. Circuit-level and block-level techniques, such as a proposed high-compliance voltage cell, have been used for implementing HV circuits in a low-voltage CMOS process. Experimental validation with an electrical model of the electrode-tissue interface showed that (1) the neural stimulator can handle voltage supplies up to 4 times higher than the technology's nominal supply, (2) residual charge-without passive discharging phase-was below 0.12% for the whole range of stimulation currents, (3) a stimulation current of 2 mA can be delivered with a voltage drop of 0.9 V, and (4) an overall power efficiency of 48% was obtained at maximum stimulation current.


Assuntos
Fontes de Energia Elétrica , Eletricidade , Eletrodos , Desenho de Equipamento
8.
Sensors (Basel) ; 22(17)2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-36081074

RESUMO

Facing the electricity market environment, in which the traditional power grid is transformed into a smart grid, power retailers with a generator background are designing new business models of cold-heat-electricity multi-energy supply based on the Internet of Things data collection, interconnection, computing and other technical supports. On the other hand, through internet of things real-time monitoring technology, the necessity of setting up energy security for power retailers is explored to enhance the control's ability to deal with the risks of electricity sales. Firstly, based on internet of things data analysis, retail strategies such as cooling-heat-electricity multi-energy packages, desulphurization and carbon emissions and energy conservation are designed. Then, a revenue cost measurement model based on the generator background of the power retailers is established. A source of data for the expansion of power retailers and the proliferation of load users is provided through the real-time monitoring of new business models that consider the operation of energy conservation on the supply and use side. Finally, an analysis based on the detection of operation under the scenarios constructed in the example of coal price market fluctuations and proliferation stagnation of user-side packages is conducted. It is verified that the power retailers with a generator background can effectively weaken the adverse impact of upward fluctuations in the coal price market in the peak season of energy consumption on the cost of power retailers by setting energy conservation. At the same time, the diffusion of a new business model in the user side is improved, and the revenue source of power retailers is further expanded. Therefore, taking energy conservation as an important innovation technique of retail strategy can enhance the market competitiveness and risk control ability of power retailers.


Assuntos
Internet das Coisas , Carbono , Carvão Mineral , Comércio , Eletricidade
9.
Sensors (Basel) ; 22(17)2022 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-36081104

RESUMO

Lamb Wave (LW)-based structural health monitoring method is promising, but its main obstacle is damage assessment in varying environments. LW simulation based on piezoelectric transducers (referred to as PZTs) is an efficient and low-cost method. This paper proposes a multiphysics simulation method of LW propagation with the PZTs under temperature effect. The effect of temperature on LW propagation is considered from two aspects. On the one hand, temperature affects the material parameters of the structure, the adhesive layers and the PZTs. On the other hand, it is considered that the thermal stress caused by the inconsistency of thermal expansion coefficients among the structure, the adhesive layers, and the PZTs affect the piezoelectric constant of the PZTs. Based on the COMSOL Multiphysics, the mechanic-electric-thermal directly coupling simulation model under temperature effect is established. The simulation model consists of two steps. In the first step, the thermal-mechanic coupling is carried out to calculate the thermal stress, and the thermal stress effect is introduced into the piezoelectric constant model. In the second step, mechanic-electric coupling is carried out to simulate LW propagation, which considers the piezoelectric effect of the PZTs for the LW excitation and reception. The simulation results at -20 °C to 60 °C are obtained and compared to the experiment. The results show that the A0 and S0 mode of simulation signals match well with the experimental measurements. Additionally, the effect of temperature on LW propagation is consistent between simulation and experiment; that is, the amplitude increases, and the phase velocity decreases with the increment of temperature.


Assuntos
Eletricidade , Transdutores , Simulação por Computador , Temperatura
10.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 91-94, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36085606

RESUMO

In recent years, wearable mid-activity electrical bioimpedance (EBI) sensing has been used to non-invasively track changes in edema and swelling levels within human joints. While the physiological origin of the changes in mid-activity EBI measurements have been demonstrated, EBI waveform patterns during activity have not been explored. In this work, we present a novel approach to extract waveform features from EBI measurements during gait to estimate the changes in vertical ground reaction forces (vGRF) corresponding to fatigue. Wearable EBI and vGRF data were measured from six healthy subjects during an asymmetric fatiguing protocol. For the exercised leg, the first peak of vGRF corresponding to the initial phase of simple support, decreased significantly and the loading rate increased significantly between the beginning and the end of the protocol. No significant change in these parameters were observed for the control leg. The first peak of vGRF and loading rate during the protocol (15 walking sessions) were correlated to the multi-frequency EBI features with mean Pearson's r=0.81 and r=0.777, respectively. The results of this proof-of-concept study demonstrate the feasibility of estimating biomechanical parameters during activity with wearable EBI. Clinical Relevance - The proposed wearable system and associated signal processing could enable convenient tracking of changes in vGRFs during daily living activities, allowing physiotherapists and doctors to remotely monitor the progress and adherence of their patients and thereby reducing the number of clinical visits.


Assuntos
Eletricidade , Dispositivos Eletrônicos Vestíveis , Fadiga , Marcha , Humanos , Extremidade Inferior , Caminhada
11.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 3939-3942, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36085730

RESUMO

Transcranial magnetic stimulation (TMS) is capable of stimulating neurons in the brain non-invasively and provides numerous possibilities for the treatment of various neurological disorders such as major depressive disorder, Parkinson's disease, obsessive compulsive disorder. TMS coils can affect the distribution of induced electric fields significantly, thus the design of TMS coils is always a popular topic in TMS studies. Yet the importance of the role of anatomical structures in the induced electric field has not been thoroughly investigated. Therefore, this work has compared the strength of electric fields induced from fifty realistic head models with twelve commercial or novel TMS coils to explore how anatomical structures affect the electric field. It has been found that the electric field strengths among the fifty head models showed highly correlated patterns. The coils were placed at two positions, where all the twelve coils were placed at the vertex and eight of them were placed at the dorsolateral prefrontal cortex of the head due to the coil geometry. Notably, fifty heterogeneous head models that are derived from MRI data were used in the simulations for examining the difference on the performance of TMS coils caused by different anatomical structures. A total of one thousand simulations have been conducted, providing a large amount of data for analysis. Clinical Relevance- This provides a basis to make treatment protocols or predictions in TMS clinical trials considering the different anatomical structures among subjects.


Assuntos
Transtorno Depressivo Maior , Estimulação Magnética Transcraniana , Encéfalo , Eletricidade , Cabeça , Humanos
12.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 4127-4130, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36085762

RESUMO

Extracting information from the peripheral nervous system with implantable devices remains a significant challenge that limits the advancement of closed-loop neural prostheses. Linear electrode arrays can record neural signals with both temporal and spatial selectivity, and velocity selective recording using the delay-and-add algorithm can enable classification based on fibre type. The maximum likelihood estimation method also measures velocity and is frequently used in electromyography but has never been applied to electroneurography. Therefore, this study compares the two algorithms using in-vivo recordings of electrically evoked compound action potentials from the ulnar nerve of a pig. The performance of these algorithms was assessed using the velocity quality factor (Q-factor), computational time and the influence of the number of channels. The results show that the performance of both algorithms is significantly influenced by the number of channels in the recording array, with accuracies ranging from 77% with only two channels to 98% for 11 channels. Both algorithms were comparable in accuracy and Q-factor for all channels, with the delay-and-add having a slight advantage in the Q-factor.


Assuntos
Eletricidade , Próteses Neurais , Animais , Eletrodos , Eletromiografia , Funções Verossimilhança , Suínos
13.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 760-763, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36085807

RESUMO

Transcranial alternating current stimulation (tACS) is a neuromodulatory technique that is widely used to investigate the functions of oscillations in the brain. Despite increasing usage in both research and clinical settings, the mechanisms of tACS are still not completely understood. To shed light on these mechanisms, we injected alternating current into a Jansen and Rit neural mass model. Two cortical columns were linked with long-range connections to examine how alternating current impacted cortical connectivity. Alternating current injected to both columns increased power and coherence at the stimulation frequency; however this effect was greatest at the model's resonant frequency. Varying the phase of stimulation impacted the time it took for entrainment to stabilize, an effect we believe is due to constructive and destructive inteference with endogenous membrane currents. The power output the model also depended on the phase of the stimulation between cortical columns. These results provide insight on the mechanisms of neurostimulation, by demonstrating that tACS increases both power and coherence at a neural network's resonant frequency, in a phase-dependent manner.


Assuntos
Eletricidade , Estimulação Transcraniana por Corrente Contínua , Encéfalo
14.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 1418-1422, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36085866

RESUMO

It is difficult to electrocute (induce ventricular fibrillation) with capacitive discharge shocks. With small capacitance values, the high voltages required for the necessary charge are rarely seen in industrial situations (e.g. electric vehicle charging stations). On the other hand, with large capacitance values, the discharge time is so great that the shock couples inefficiently with the cardiac cells. The update to IEC 60479-2 sets the C1 "mostly-safe" charge limit of 3 mC for a short "impulse function" pulse. We calculated the equivalent capacitor stored charge for an arbitrary capacitance value using the simple single membrane time constant model for the cardiac response. The peak membrane response was set equal to that of the 3 mC impulse function response to calculate the safe values for stored charge, voltage, and energy. The total stored charge, per se, cannot be used simplistically to estimate the danger of a capacitive discharge shock. A capacitive-discharge shock cannot be accurately compared to a rectangular shock with a duration equal to the shock time constant. The greater the capacitance, the larger the fraction of wasted charge in coupling to the heart and thus the shorter equivalent duration compared to the shock time constant. For a capacitive discharge shock this translates to a stored charge of 3 mC increasing up to 9 mC for a 10 capacitor using the assumed 575 load for an electric-vehicle (EV) charging station. In the area of interest for 1 - 10 the safe voltage ranges from 1300 to 4700 V, which includes the 1500-VDCscope of EV charger standard IEC 61851-23. For C > 100 the voltage asymptote is 700 V.


Assuntos
Líquidos Corporais , Choque , Capacitância Elétrica , Fontes de Energia Elétrica , Eletricidade , Humanos
15.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 1715-1718, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36085882

RESUMO

This study models and investigates whether temporally interfering electric fields (TI EFs) could function as an effective non-invasive brain stimulation (NIBS) method for deep brain structure targeting in humans, relevant for psychiatric applications. Here, electric fields off- and on-target are modelled and compared with other common NIBS modalities (tACS, TMS). Additionally, local effects of the field strength are modelled on single-compartment neuronal models. While TI EFs are able to effectively reach deep brain targets, the ratio of off- to on-target stimulation remains high and comparable to other NIBS and may result in off-target neural blocks. Clinical Relevance- This study builds on earlier work and demonstrates some of the challenges -such as off-target conduction blocks- of applying TI EFs for targeting deep brain structures important in understanding the potential of treating neuropsychiatric conditions in the future.


Assuntos
Encéfalo , Técnicas Estereotáxicas , Citoesqueleto , Eletricidade , Modelos Epidemiológicos , Humanos
16.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 975-978, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36085888

RESUMO

Tumor-treating Fields (TTFields) is a promising cancer therapy technique in clinical application. Computational simulation of TTFields has been used to predict the electric field (EF) distribution in the human body and to optimize the treatment parameters. However, there are only a few studies to validate the accuracy of the simulation model. Here we propose a measurement platform with technical details for validating the simulation model of TTFields. We further constructed homogeneous agar phantoms with different conductivity for voltage measurement. With the measured voltages from six equidistance recording points in the cylinder phantom, we calculated the EF intensity in the phantoms at different frequencies. Comparing the measured values with the simulated values obtained from two types of source simulation, we found that the current source simulation model of TTFields is a reliable method for evaluating the EF intensity distribution.


Assuntos
Neoplasias , Ágar , Simulação por Computador , Eletricidade , Humanos , Neoplasias/terapia , Imagens de Fantasmas
17.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 1565-1568, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36086199

RESUMO

In this paper, a broadband microwave device for cell poration is presented, that enables the analysis of the relation between frequency, electrical field strengths and temperature for a successful cell poration. Electromagnetic-thermal coupled simulations in the frequency range from 1 GHz to 10 GHz show that the device reaches electrical field strengths of 100 V/cm and temperatures lower then 40°C. Electroporation experiments with adherent C2C12 mouse myoblast cells show successful uptake of an anti-histone γ -H2A.X nanobody at a frequency of 10 GHz. This MWP device allows the fast electro-poration of adherent cells. After 15 min, the cells show uptake of γ -H2A.X-specific nanobody while most of them survived.


Assuntos
Eletroporação , Micro-Ondas , Animais , Eletricidade , Camundongos , Temperatura
18.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 2294-2297, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36086211

RESUMO

To evaluate the hemocompatibility of individual components of our pediatric left ventricular assist device (LVAD), we proposed a hemocompatibility assessment platform (HAP) with a magnetic levitated bearing system. The HAP consists of a drive system utilizing a brushless direct current (BLDC) motor, passive magnetic bearings (PMB), and an active magnetically levitated bearing (AMB) to reduce the hemolysis generated by HAP itself. In this study, we designed and evaluated the performance of the AMB by measuring radial and axial displacements of the rotor resulting from radially destabilizing forces as well as the performance of the drive system when rotated at increasing speeds to 1,200 rotations per minute (rpm). The results show that, with radial disturbance, the AMB is capable of maintaining axial stability for the BLDC motor system. The AMB can control up to 1,200 rpm without any contact between the rotor and stator. Future work includes geometry optimization for the AMB structure and increase the capability to control stable high-speed rotation for the entire system. Clinical Relevance- This work furthers the development of the magnetic levitated bearing system for a hemocompatibility assessment platform that will be used to enhance and accelerate the development of adult and pediatric LVADs.


Assuntos
Coração Auxiliar , Magnetismo , Criança , Eletricidade , Desenho de Equipamento , Coração Auxiliar/efeitos adversos , Hemólise , Humanos
19.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 3447-3450, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36086217

RESUMO

In this work, a stream function inverse boundary element method (IBEM) has been used for designing different deep transcranial magnetic stimulation (dTMS)coils to activate the prefrontal cortex and the temporal lobe have been set as the target regions. In addition, the performances of these coils have been described and the electric field induced by them has been obtained by using a computational forward technique. These results show that the stream function IBEM is an ideal approach to design optimal dTMS coils capable of producing deep stimulation in the target brain regions. Clinical relevance - The design problem proposed here can be used to produce efficient dTMS stimulators for neurological disorders, which can overcome some of the currently existing limitations of the most common devices employed in TMS.


Assuntos
Doenças do Sistema Nervoso , Estimulação Magnética Transcraniana , Encéfalo/fisiologia , Eletricidade , Desenho de Equipamento , Humanos , Estimulação Magnética Transcraniana/métodos
20.
Annu Int Conf IEEE Eng Med Biol Soc ; 2022: 4362-4365, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36086350

RESUMO

This work aimed to estimate the distribution of the electric field generated by a combined cerebellar and frontal transcranial direct current stimulation (tDCS) for treatment-resistant depression using electromagnetics computational techniques applied to a realistic head human model. Results showed that the stronger electric fields occur mainly in the cerebellum and in DLPFC areas, where the two pairs of electrodes were applied. Furthermore, the study demonstrated that the simultaneous use of the two pairs of electrodes did not imply a lower effectiveness of the tDCS technique, in fact the electric field distributions in the primarily targets of the anatomical regions (i.e., cerebellum and DLPFC) were very similar to when the pairs of electrodes were applied separately.


Assuntos
Estimulação Transcraniana por Corrente Contínua , Cerebelo , Depressão , Eletricidade , Eletrodos , Humanos , Estimulação Transcraniana por Corrente Contínua/métodos
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