Portable Applications Research Articles

Fabrication and assessment of poly(lactic acid) - poly(4-styrene sulfonate) flexible membranes as electrodes for supercapacitors

Flexible supercapacitors have become a popular research area as an energy storage technology for powering portable gadgets because of their high areal capacitance. The present work describes the preparation of flexible films of poly(lactic acid) and poly(4-styrene sulfonate) as electrode material for supercapacitors. The techniques like Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), water contact angle (WCA), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze physicochemical properties and cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD) were used to analyze electrochemical properties of developed flexible films. An electrode film exhibited maximum areal capacitance of 303.5 mF cm−2 at 0.2 mA cm−2 current density with energy density 15.8 μWh cm−2 and power density 243.9 μW cm−2 and showed capacitance retention of 66.69 % after prolonged 1000 cycles. The fabricated micro supercapacitor device achieved an areal capacitance of 490.3 mF cm−2 at 0.3 mA cm−2 current density, which provides a platform for making large-scale supercapacitor devices for industrial applications.

Multi‐objective design optimization of microreactor arrays for distributed renewable energy conversion: A case study

AbstractRenewable energy accommodation entails extensive use of modular devices, whose performance degrades remarkably from the lab scale to the industrial scale. This work presents a multi‐objective design optimization approach for modular devices scale‐up as exemplified by hierarchical numbering‐up of reverse water‐gas shift microreactors. The optimization objectives cover a wide span of competing system performance metrics, including the reaction performance, energy efficiency, space occupation, environmental impact, and costs. The decision variables involve the hierarchical geometry, branching, and inter‐stack connection schemes of the microreactor stacks. The obtained Pareto‐optimal designs suggest that multiple short stacks with small intra‐stack distribution channels and large inter‐stack connection tubes can well balance cost and performance. Meanwhile, single‐stack structures with large distribution channels are more suitable for portable applications. The methodology not only can be extended to the numbering‐up of various types of microreactors but also has essential guidance for the integration design of other modular devices.

Design and structural characteristics of conducting polymer-metal organic framework composites for energy storage devices

The popularity of portable gadgets has increased the supply for energy storage systems with significant power and energy densities Redox-active conducting polymers (CPs) have mechanical qualities similar to polymers and electrical conductivity properties similar to metals. Unfortunately, the volume changes that occur throughout the charge and discharge procedures cause them to function poorly. An efficient method to attain high performance is to combine CPs with metal-organic frameworks (MOF) to create composites. Despite MOFs' extraordinary interior surface areas and adaptable pore structures, they have poor stability, polymers can improve MOF stability and improve other crucial characteristics like electrical conductivity. The combination of these two different components can result in a variety of desired features that are not always attained by these components individually. The recent research on conducting polymer-based metal-organic framework (CP/MOF) composites for energy storage applications is thoroughly surveyed in this review paper. This review focuses on various CP/MOF-based fuel cells, batteries and supercapacitors, pertinent fabrication techniques, and important design principles.

Experimental study of an optical concentrated solar thermoelectric power generator

The commercial thermoelectric modules become more and more efficient in terms of mechanical reliability, cooling capacity (in Peltier mode), power generation (in Seebeck mode), tolerable thermal conditions and so on. In this paper a portable optical concentrated solar thermoelectric generator is proposed, designed, tested, and evaluated based on a single UTX15-288-F2 module in both transient and steady-state conditions. A 30 cm diameter optical concentrator is employed to concentrate the solar power on one side of thermoelectric. Due to the low scale of the generated power, the active cooling methods for the other side of the module is not desirable and economical. That is why the boundary condition of the other low temperature side of thermoelectric is just natural convection by a heatsink under shadow condition. The aim of this case study is to clarify the UTX15-288-F2 module behavior under the mentioned conditions for possible portable micropower applications. Generated power, solar radiation, temperature of both side of the module and ambient conditions are measured during the experiments, reported, discussed, and analyzed.

A Binder‐Free and Flexible VOPO4/CNT Film as Cathode for Aqueous Rechargeable Zn‐Metal Battery

AbstractAqueous rechargeable Zn‐metal batteries (AZMBs) are promising energy storage aids due to their inherent safety, low cost, and competent performance, with prospects in stationary and portable applications. In this regard, one of the critical requirements is developing electrodes that can adapt to mechanical deformation without compromising the charge storage performance. The current work demonstrates the development of a binder‐free and mechanically flexible composite cathode film (VP/fCNT‐F, where ‘F’ stands for the film) based on VOPO4 (VP) and functionalized carbon nanotubes (fCNTs). The VP/fCNT‐F film processing involves simple vacuum filtration of the composite obtained from the in‐situ reaction of the fCNTs and the VP precursor in an aqueous medium. The functionalization of carbon nanotube (CNT) is important for the homogenous dispersion of VP and fCNT. The VP/fCNT‐F electrode is used as a monolithic electrode in AZMB cells in combination with both liquid and quasi‐solid‐state gel polymer electrolytes. Besides, the utility of the VP/fCNT‐F electrode in a flexible battery configuration is also demonstrated. Interestingly, in both the coin‐cell and flexible configurations, the VP/fCNT‐F electrode delivers a comparable discharge capacity of 90 and 78 mAh g−1, respectively (at 0.1 A g−1), validating the advantage of the binder‐free VP/fCNT‐F electrode for AZMBs.

Piezoelectric fibers-based PVDF-ZnS-carbon nano onions as a flexible nanogenerator for energy harvesting and self-powered pressure sensing

Herein, an innovative piezoelectric nanogenerator (PENG) is fabricated by electrospun polyvinylidene fluoride (PVDF) and a hybrid nanofiller comprised of zinc sulfide nanorods (ZnS NRs) and carbon nano onion particles (CNOs). From a mechanistic point of view, it has been determined that ZnS nanorods contribute to the alignment of the electric dipoles in PVDF and enhance the overall piezoelectric properties of the composite nanofibers because of their intrinsic piezoelectric ability. CNOs as a family of carbon allotropes with electrical conductivity as well as easy preparation method from natural source of castor oil as a cost-effective preparation method can improve the piezoelectric performance of PVDF nanofibers by positively enhancing the charge transfer rate and thereby enabling the alignment of PVDF’s electric dipoles. The developed PVDF-ZnS-CNOs composite (with 0.15 wt% of CNOs loading) based PENG exhibited improved electrical functionality and stability. The maximum power density of approximately 30.15 μW/cm2, the load resistance of 1.0 MΩ, the open-circuit voltage of 14 V, and the short-circuit current of 35 μA were observed. In addition to evaluate the energy harvesting and sensing capabilities, the constructed PENG was utilized to identify numerous types of human movements, and several capacitors were charged. It was observed that a capacitor with a 1 µF capacity could be charged to 9.5 V under mechanical stimulation in 45 s, which shows a promising platform for eliminating the need for an external power source to operate portable gadgets. Consequently, the developed PENG possess high potential, which can be utilized as an alternative to conventional power supplies in self-powered devices by taking advantage of their flexibility and stability.

A METAMATERIAL INSPIRED SPLIT RING RESONATOR ACCOMPLISHED MULTIBAND ANTENNA FOR 5G AND OTHER WIRELESS APPLICATIONS

A multiband antenna is proposed in this paper, accomplished with a split ring resonator (SRR) in the ground plane for portable and wireless applications. The rectangular radiator is unified with a semi-circular stub improving the impedance matching in the antenna. Further, the radiator creates an optimized rectangular slot to obtain the multiband operation. The SRR in the ground plane demonstrates the metamaterial (MTM) characteristics that significantly improve the 10 dB impedance bandwidths (IBW) and enhance realized gain in the multi-band antenna. The proposed antenna is procuring the five 10 dB IBW, which can be prominent for RADAR (2.96 GHz - 3.06 GHz), 5G (3.92 GHz - 4.32 GHz and 4.64 GHz - 5.04 GHz), WLAN (5.32 GHz - 5.64 GHz) and ISM band (5.7 GHz - 6 GHz) applications. The gain enhancement is obtained in all operating bands of the antenna, and a maximum 5.24 dB gain is achieved at a 4.14 GHz frequency.

Mutual Information Based Fusion Model (MIBFM): Mild Depression Recognition Using EEG and Pupil Area Signals

The detection of mild depression is conducive to the early intervention and treatment of depression. This study explored the fusion of electroencephalography (EEG) and pupil area signals to build an effective and convenient mild depression recognition model. We proposed Mutual Information Based Fusion Model (MIBFM), which innovatively used pupil area signals to select EEG electrodes based on mutual information. Then we extracted features from EEG and pupil area signals in different bands, and fused bimodal features using the denoising autoencoder. Experimental results showed that MIBFM could obtain the highest accuracy of 87.03%. And MIBFM exhibited better performance than other existing methods. Our findings validate the effectiveness of the use of pupil area as signals, which makes eye movement signals can be easily obtained using high resolution camera, and the EEG electrode selection scheme based on mutual information is also proved to be an applicable solution for data dimension reduction and multimodal complementary information screening. This study casts a new light for mild depression recognition using multimodal data of EEG and pupil area signals, and provides a theoretical basis for the development of portable and universal application systems.

Challenges and outlook for lithium-ion battery fault diagnosis methods from the laboratory to real world applications

Lithium-ion batteries are the ideal energy storage device for numerous portable and energy storage applications. Efficient fault diagnosis methods become urgent to address safety risks. The fault modes, fault data, fault diagnosis methods in different scenarios, i.e., laboratory, electric vehicle, energy storage system, and simulation, are reviewed and compared comprehensively. The data characteristics, performance and limitations of fault diagnosis methods are discussed further. The results show that the fault diagnosis methods of laboratory scenario are more advanced than real-world applications because of the clean and perfect dataset, advanced equipment, and ideal operating conditions. At last, the outlook and challenges for applying fault diagnosis methods from laboratory to real-world applications are investigated from three aspects: unified framework of fault diagnosis methods, cloud big data fusion, and application of laboratory measurement technologies. To realize more accurate fault diagnosis in real-world applications within the advanced research of laboratory, more significant work is still needed.

Reproducible and Portable Big Data Analytics in the Cloud

Cloud computing has become a major approach to help reproduce computational experiments. Yet there are still two main difficulties in reproducing batch based big data analytics (including descriptive and predictive analytics) in the cloud. The first is how to automate end-to-end scalable execution of analytics including distributed environment provisioning, analytics pipeline description, parallel execution, and resource termination. The second is that an application developed for one cloud is difficult to be reproduced in another cloud, a.k.a. vendor lock-in problem. To tackle these problems, we leverage serverless computing and containerization techniques for automated scalable execution and reproducibility, and utilize the adapter design pattern to enable application portability and reproducibility across different clouds. We propose and develop an open-source toolkit that supports 1) fully automated end-to-end execution and reproduction via a single command, 2) automated data and configuration storage for each execution, 3) flexible client modes based on user preferences, 4) execution history query, and 5) simple reproduction of existing executions in the same environment or a different environment. We did extensive experiments on both AWS and Azure using four big data analytics applications that run on virtual CPU/GPU clusters. The experiments show our toolkit can achieve good execution performance, scalability, and efficient reproducibility for cloud-based big data analytics.

Transient Analysis and Low Power Consumption of Oscillator using C-mos Technology at 90 nm

The design and analysis of an oscillator in 90 nm technology using the cadence virtuoso tool. This oscillator has less noise and power consumption. There is also evidence of oscillator periodic steady state response. The portable power supplies, such as solar cells or other devices, it is crucial that electronic devices and circuits that can work at low voltages for portable electronic applications.

Enhanced toluene gas-sensing properties of MEMS sensor based on Pt-loaded SnO2 nanoparticles

Rapid detection of low concentration toluene is highly desirable in environment monitoring, industrial processes, medical diagnosis, etc. In this study, we prepared Pt-loaded SnO2 monodispersed nanoparticles through hydrothermal method and assembled a sensor based on micro-electro-mechanical system (MEMS) to detect toluene. Compared with the pure SnO2, the 2.92 wt% Pt-loaded SnO2 sensor exhibits a 2.75 times higher gas sensitivity to toluene at about 330 °C. Meanwhile, the 2.92 wt% Pt-loaded SnO2 sensor also has a stable and good response to 100 ppb of toluene. Its theoretical detection limit is calculated as low as 12.6 ppb. Also, the sensor has a short response time of ∼10 s to different gas concentrations, as well as the excellent dynamic response—recovery characteristics, selectivity, and stability. The improved performance of Pt-loaded SnO2 sensor can be explained by the increase of oxygen vacancies and chemisorbed oxygen species. The electronic and chemical sensitization of Pt to SnO2-based sensor, together with small size and fast gas diffusion of the MEMS design ensured fast response and ultra-low toluene detection. This provides new ideas and decent prospect for developing miniaturized, low-power-consumption, and portable application of gas sensing devices.

A 0.053 mm2 10-bit 10-ks/s 40-nW SAR ADC with pseudo single ended switching procedure for bio-related applications

This paper presents a power and area efficient pseudo single ended switching ADC for portable biomedical signal monitoring applications. The switching method features an 8-bit binary-weighted DAC array with a novel layout method called limited bottom-plate routing (LBPR) maintaining both feasibility and symmetry, a dynamic biased comparator and dynamic control logic. As a result, the proposed ADC saves 96.7% power consumption and 87.5% area occupation compared with conventional SAR ADC. Also, a novel DAC array layout method is promoted maintaining both feasibility and symmetry. A prototyped chip including a proposed ADC is fabricated in a 0.13 μm CMOS process. On condition of 0.6 V supply voltage and 10 kS/s sampling rate, the measured signal-to-noise-distortion (SNDR) and spurious free dynamic range (SFDR) are 57.8 dB and 64.3 dB, respectively. Besides, the ADC consumes only 40 nW power and 0.053 mm2 area achieving a figure-of-merit (FoM) of 6.26 fJ/conversion-step. Low power and low area occupation make it a good candidate for biomedical signal monitoring applications.

Inverse-Designed Multi-Level Diffractive Doublet for Wide Field-of-View Imaging

Wide field-of-view (WFOV) imaging is extensively used in fields as diverse as macro photography, virtual reality, machine vision, and microscopy. Conventional WFOV cameras are bulky since they require multiple refractive lenses. Here, we design, fabricate, and characterize a 100° FOV camera with a total-track length of ∼2 mm, composed of an inverse-designed multi-level diffractive doublet with an input-aperture diameter of 0.204 mm, a back-focal length of 1 mm, and operating at λ = 850 nm (bandwidth ∼ 34 nm). Using careful experiments, we characterize the focusing and imaging performance as well as demonstrate de-vignetting based on experimental calibration. The spatial frequency at 10% modulation-transfer-function contrast was measured at 150 and 38 lp/mm for 0 and 50° incident angles, respectively. Our approach can be scaled to larger aperture sizes and smaller f/#s, potentially leading to thin, lightweight WFOV cameras for portable applications.

Switched-Resistor Passive Balancing of Li-Ion Battery Pack and Estimation of Power Limits for Battery Management System

The battery pack performance and expected lifespan are crucial in electric vehicle applications. Balancing the charge on a battery pack connected in series and parallel is crucial due to manufacturing discrepancies and distinct performance of each cell in a standard battery pack. In this paper, a switched-resistor passive balancing-based method is proposed for balancing cells in a battery management system (BMS). The value of the available voltage at the battery cell terminals is balanced using resistors in an electrical circuit, and the excess voltage is eliminated. The cell balancing outcome demonstrates that the electrical circuit can maintain an even voltage across each cell. The procedure of balancing involves individually adjusting each cell’s level of charge. Passive balancing releases energy as heat by draining charge from cells that have too much charge. A passive cell balancer is a cost-effective solution and easy to install, but due to thermal loss from a resistor, it has a low energy efficiency for cell balancing and necessitates a lengthy balancing process. This passive cell balancer is an effective and reliable method for low-power devices and portable applications such as electrical vehicles. The power limits during charging and discharging are estimated using the bisection method.

Hidden Macroscopic Degradation Behavior in Rechargeable Lithium–Oxygen Batteries under Lean Electrolyte and High Areal Capacity Conditions

As lithium–oxygen batteries (LOBs) possess extremely high theoretical energy densities that exceed those of lithium-ion batteries, they are regarded as promising candidates for portable energy applications, including as power sources for next-generation electrical devices. However, physical degradation factors affecting the prolonged cycle of the LOBs, such as electrode volume changes and electrolyte displacement, have been rarely explored thus far, owing to the technical difficulty of applying non-destructive analytical methods to LOBs during cycling. In the present study, we employed ex situ X-ray computerized tomography (XCT), in situ internal pressure monitoring, and in situ confocal microscopy to study the physical states of the electrodes and the electrolyte in high energy density LOBs. The analysis results reveal that large irreversible volume changes occurred in both the positive electrode and the negative electrode of the LOB cells. Furthermore, it was also confirmed that the electrolyte was displaced from the pores of the positive electrode associated with the formation of Li2O2 in these pores during the discharge process. As these results present new fundamental insights into the physical behavior of LOBs during cycling conditions, the methodologies demonstrated here are therefore effective means to gain a new understanding of complex physical processes previously unexamined in LOBs, which shed light on the future design strategies of LOBs with high energy density and long cycle life.

Digital marketing and it’s impact on the buying behaviour of the consumers

In this highly competitive and innovation progression market the use of web has increased unexceptionally which have forced the market to move from traditional old form to new digital marketing. The recent expansion and advancement of web use or commitment of buyer and sellers have increased as the result of which consumers approach is changing and companies should have in depth examination of it. Therefore, this research studies is conducted to analyse the impact of digital marketing on the consumer’s buying behaviour in this cutthroat market. Digital marketing refers to the way through which one can display alludes to promotion depicted by using advanced channels like online entertainment, emails and portable applications. It give customer open doors to examine the product launched by companies and do comparison accordingly. Customer has access to products not only within the countries but throughout the world and all these has become possible only through digital marketing.

Layered Structures of Enriched V5+ States of Vanadium Oxide as a Hybrid Cathode Material for Long-Cyclable Aqueous Zinc-Ion Batteries.

Recently, aqueous zinc-ion batteries (AZIBs) have garnered much attraction because of their ecofriendly nature, cost effectiveness, and reliability. However, there are still many challenges in developing suitable cathode materials for practical usage in ZIBs. In this work, we have synthesized a layered V5+-rich vanadium oxide (V6O13) flaky structure that provided the electrolyte with a large active surface area. In addition to that, the mixed (V4+/V5+) valence states of V have significantly improved the ionic diffusion of Zn2+, thereby improving the V6O13 electrical conductivity. Therefore, the AZIBs based on the layered structure V6O13 cathode with 1 M ZnSO4 electrolyte exhibited a very high specific capacity of 394 mAh g-1 @ 0.1 A g-1 without the addition of any additives or electrode modification. The rate capability and cycle life are investigated at the current density of 2 A g-1, where the capacity retention was found to be around 94% along with a coulombic efficiency of 96% for over 100 cycles. Such a material with high electrochemical performance can be used for portable electronic devices and electric vehicular applications.

Clinical concept and relation extraction using prompt-based machine reading comprehension.

To develop a natural language processing system that solves both clinical concept extraction and relation extraction in a unified prompt-based machine reading comprehension (MRC) architecture with good generalizability for cross-institution applications. We formulate both clinical concept extraction and relation extraction using a unified prompt-based MRC architecture and explore state-of-the-art transformer models. We compare our MRC models with existing deep learning models for concept extraction and end-to-end relation extraction using 2 benchmark datasets developed by the 2018 National NLP Clinical Challenges (n2c2) challenge (medications and adverse drug events) and the 2022 n2c2 challenge (relations of social determinants of health [SDoH]). We also evaluate the transfer learning ability of the proposed MRC models in a cross-institution setting. We perform error analyses and examine how different prompting strategies affect the performance of MRC models. The proposed MRC models achieve state-of-the-art performance for clinical concept and relation extraction on the 2 benchmark datasets, outperforming previous non-MRC transformer models. GatorTron-MRC achieves the best strict and lenient F1-scores for concept extraction, outperforming previous deep learning models on the 2 datasets by 1%-3% and 0.7%-1.3%, respectively. For end-to-end relation extraction, GatorTron-MRC and BERT-MIMIC-MRC achieve the best F1-scores, outperforming previous deep learning models by 0.9%-2.4% and 10%-11%, respectively. For cross-institution evaluation, GatorTron-MRC outperforms traditional GatorTron by 6.4% and 16% for the 2 datasets, respectively. The proposed method is better at handling nested/overlapped concepts, extracting relations, and has good portability for cross-institute applications. Our clinical MRC package is publicly available at https://github.com/uf-hobi-informatics-lab/ClinicalTransformerMRC.

Anodic Catalyst Support via Titanium Dioxide-Graphene Aerogel (TiO2-GA) for A Direct Methanol Fuel Cell: Response Surface Approach

The direct methanol fuel cell (DMFC) has the potential for portable applications. However, it has some drawbacks that make commercialisation difficult owing to its poor kinetic oxidation efficiency and non-economic cost. To enhance the performance of direct methanol fuel cells, various aspects should be explored, and operational parameters must be tuned. This research was carried out using an experimental setup that generated the best results to evaluate the effectiveness of these variables on electrocatalysis performance in a fuel cell system. Titanium dioxide-graphene aerogel (TiO2-GA) has not yet been applied to the electrocatalysis area for fuel cell application. As a consequence, this research is an attempt to boost the effectiveness of direct methanol fuel cell electrocatalysts by incorporating bifunctional PtRu and TiO2-GA. The response surface methodology (RSM) was used to regulate the best combination of operational parameters, which include the temperature of composite TiO2-GA, the ratio of Pt to Ru (Pt:Ru), and the PtRu catalyst composition (wt%) as factors (input) and the current density (output) as a response for the optimisation investigation. The mass activity is determined using cyclic voltammetry (CV). The best-operating conditions were determined by RSM-based performance tests at a composition temperature of 202 °C, a Pt/Ru ratio of (1.1:1), and a catalyst composition of 22%. The best response is expected to be 564.87 mA/mgPtRu. The verification test is performed, and the average current density is found to be 568.15 mA/mgPtRu. It is observed that, after optimisation, the PtRu/TiO2-GA had a 7.1 times higher current density as compared to commercial PtRu. As a result, a titanium dioxide-graphene aerogel has potential as an anode electrocatalyst in direct methanol fuel cells.