Transmission Path Length Research Articles

Exploring Ion Transport Dynamics in Liquid Electrolytes: Insights from in-Situ FTIR Imaging of Lithium Electrodes

While solid-state batteries have demonstrated potential in enhancing metal electrode stability, achieving the same stability in liquid electrolytes remains elusive. The instability of the SEI plays a pivotal role in the stability of metal electrodes in liquid electrolytes. Despite several promising strategies to stabilize metal electrodes in liquid electrolytes, the intricate relationship between the composition of the liquid electrolyte and the formation and stability of the SEI is still not fully understood.This study delves into the constraints of ion transport in liquid electrolytes, specifically focusing on the process of lithium plating and stripping on metal electrodes. A customized short pathlength transmission flow cell, equipped with symmetric lithium electrodes, is employed to simultaneously image lithium deposition, capture electrochemical measurements, and perform in-situ Fourier Transform Infrared (FTIR) imaging. This methodology illuminates the complex relationship between electrolyte transport, local composition, and the morphology of lithium plating.The research utilizes quantitative analysis of electrolyte components, Li+, PF6-, EC, and EMC, through spectral analysis with chemometric methods and machine learning. The composition of the local electrolyte, which undergoes significant changes under rapid charge conditions, impacts SEI composition, and by extension lithium plating morphology. In situ FTIR imaging, with a resolution of five microns, is used to evaluate the role of preferential diffusion and/or migration of solvent and ionic species. Synchronized optical imaging, with a superior resolution of one micron, providing visual images of lithium structures that are correlated with solvent and ion concentration distributions measured in the infrared. The findings establish a link between ion transport dynamics and the efficiency of lithium plating and stripping, which has far-reaching implications for the performance and safety of electrochemical systems.

Data transmission path planning method for wireless sensor network in grounding grid area based on MM‐DPS hybrid algorithm

AbstractAt present, in order to conduct non‐destructive testing on the grounding grid of substations under the condition of continuous power supply and no excavation, researchers have applied wireless technology based on electrochemical methods to remotely monitor the corrosion state of grounding conductors online. Nevertheless, wireless signals are affected by the environment when they are transmitted underground. In the field of grounding gird wireless monitoring, how to plan the information transmission path of wireless sensor network (WSN) with high accuracy of data transfer and low energy consumption earns growing research attention. To address the problem of WSN path planning in grounding grid area, a path planning method for WSN based on the hybrid algorithm of map‐matching algorithm and double‐pole search algorithm (MM‐DPS) is proposed in this paper. The map‐matching algorithm is employed to calculate the optimal sampling node number of the data transmission path. On the basis of the optimal sampling node number, the double‐pole search algorithm is employed in seeking out each sensor node of the path, and two groups of path plans are obtained. In the simulation experiment, compared with the A‐star algorithm, the MM‐DPS algorithm shortens the data transmission path length by about 39% and reduces the energy consumption by about 57%. The research work brings a method to alleviate the problem of data transmission underground of WSN in grounding grid area. The method not only ensures the accuracy of data transmission, but also shorts the transmission distance and reduces energy consumption.

Design and Development of Intelligent Learning System for University Innovation and Entrepreneurship Based on Knowledge Visualisation

To build a comprehensive learning resource system covering learning process, learning users, learning resources and other aspects, an intelligent learning system for innovation and entrepreneurship in universities was constructed and designed combined with knowledge visualisation theory. The system includes student information record module, system recommendation calculation module, learning material module, and knowledge visualisation module. The research focuses on the system recommendation calculation module, including the User-based Collaborative Filtering Algorithm (UCF) and the Joint Recommendation (JR) algorithm of the application content recommendation algorithm. The best neighbour number of JR is 20, and the best transmission path length is 2. The recommendation effect is optimal under this setting. The convergence iterations of the training and test set of the joint recommendation algorithm are 80 times and 100 times, respectively. For the training set and test set, the accuracy, precision, sensitivity, recall, running time, error, and other performance evaluation indicators of the joint recommendation algorithm are better than the corresponding values of other recommendation algorithms. The system has a good design effect and experience effect in the application of the online learning platform.

SnO2-MoO2 nanoparticles coated on graphene oxide as a high-capacity, high-speed, long-life lithium-ion battery anode

Ternary SnO2-MoO2-GO (SMGO) nanocomposites were synthesized by hydrothermal method, modified Hummers method, and ball milling method. SMGO nanocomposites have the following advantages, including mitigating volume expansion during cycling, enhancing conductivity, and reducing the transmission path length for both electrons and Li+. Consequently, the SMGO composite material demonstrates a capacity of 1215.2 mAh/g after 200 cycles at 0.2 Ag−1, and a capacity of 1032.9 mAh/g after 1000 cycles at 1.0 Ag−1. Moreover, subsequent SEM analysis of the electrode material reveals the absence of accumulation or notable cracks, underscoring the remarkable cycling stability of the SMGO composite material.

Vibration signal modeling of planetary gearbox based on dynamics and finite element method for tooth crack diagnosis

Planetary gear set contains many kinds of nonlinear factors, such as time-varying meshing stiffness, bearing support, backlash, and comprehensive transmission error, which will deeply affect the gearbox response behaviors and vibration characteristics. During the operation of planetary gear set, there are several gear pairs meshing simultaneously, which will lead to multiple vibration sources and complicate vibration transmission. The revolution of the planet gears makes the meshing force of the gear pairs vary periodically, and the continuous motion of the meshing point also changes the length of vibration transmission path. This study aims to establish a hybrid model that can simulate the vibration signals of gearbox measuring points through fusing the dynamic model of planetary gear set and the transmission path model. Through the simulation analysis, the vibration characteristics of the measuring point signal of the planetary gearbox are revealed, and the crack fault of the planet gear tooth is effectively isolated. Finally, the availability and validity of the presented model are experimentally verified, and the magnitude match is up to 78%. The model can not only provide a theoretical basis for data-driven fault diagnosis methods, but also solve the pain point of diagnostic samples scale and balance by simulation means.

ПОВЫШЕНИЕ ЭФФЕКТИВНОСТИ ВЫСОКОПРОИЗВОДИТЕЛЬНЫХ БЕСПРОВОДНЫХ ОПТИЧЕСКИХ КАНАЛОВ СВЯЗИ В РАЗЛИЧНЫХ ПОГОДНЫХ УСЛОВИЯХ

A common problem of traditional radio communication channels - the lack of free frequencies,noise, low bandwidth, the need to obtain a license to use the frequency, the relative ease of hacking.Free space optical communication channels overcome these limitations, is one of the types of communicationsystems that use open space to transmit information carried by light - this points to theneed for direct visibility of the transceivers. Due to the influence of various weather conditions, thelight flux is subject to atmospheric attenuation. In this paper, a method to improve the efficiency ofhigh-performance wireless optical communication channels in different weather conditions: clearsky, fog, rain and snow was investigated. The existing wireless optical communication technology, adense multiplexing multiplexing (DWDM) system with one input and one output (SISO), was considered.And it was proposed to improve the existing system by applying multiple input/output (MIMO).An impact and attenuation analysis on the wireless optical network in different weather conditionswas conducted. The study was based on the use of the Optisystem simulation software toolkit, whichis used to emulate different weather conditions of attenuation in two types of systems. Models weredeveloped for each of the optical communication systems studied. A comparison between SISO andMIMO systems is made in terms of quality factor under different weather conditions. The proposedsystem shows promising results in terms of performance and received signal quality. The transmissionpath length of the proposed system in dense fog conditions increases by 33.6%. The transmissionpath length of the proposed system in heavy rain increases by 63.89%. The transmission pathlength of the proposed system in heavy snow increases by 35,21%.

Optical properties of biochemical compositions of microalgae within the spectral range from 300 to 1700 nm.

The optical properties of biochemical compositions of microalgae are vital for the improvement of biosensor design, photobioreactor design, biofuel, and biophotonics techniques. A combination method using both the double optical pathlength transmission method (DOPTM) and the ellipsometry method (EM) is called DOPTM-EM, and it is used to acquire the optical constants of protein, lipid, and carbohydrate of Haematococcus pluvialis, Nannochloropsis sp., and Spirulina in both a solid state and a solution state within the visible and near-infrared spectral range. For different types of microalgae, the refractive indices of protein and carbohydrate in the solid state are similar to each other, but show an observed difference from lipid in the solid state. The refractive indices of protein and carbohydrate in the solution state presents a visible distinction in the researched spectral range. The absorption indices of protein, lipid, and carbohydrate in the solid state for these three types of microalgae are close to each other in the spectral range of 300-500 nm. However, an observed difference is shown in the spectral range of 500-1700 nm. For ease of application, the refractive index of biochemical composition of microalgae was fitted based on the Sellmeier equation. We believe this work can provide a reference to obtain the optical properties of biomaterial with high accuracy.

An Improved Efficiency by Surface Modification Using Pulse Laser for Partial Transparent Bifacial Solar Cell

Bifacial solar cell has symmetrical configuration contacts on front and rear surface that eliminate expansion mismatch, decrease metal usage and improves photon absorption. The limitation of the reflector at the back of bifacial solar panel able to be eliminated by developing special designed partially transparent bifacial solar cell to optimize light trapping on rear surface. Therefore, the partial transparent silicon (Si) wafers were developed to increase light transmission to rear surface. Surface modification on Si wafer was conducted to form partial transparent Si wafer. Surface modification was employed by pulsed laser interaction to create dot marking array on Si wafer. Two pulsed laser power applied were 25.5W and 39.6W to produce pattern, then immersed in 10% KOH solution to etch laser-induced structure and debris to form partial transparent Si wafer. Low power laser was induced 80-85 μm depth of micro-hole, while high power was induced 140-145 μm. KOH treatment was conducted to etch laser region which to form deeper and wide micro-holes. The bifacial solar cells have been fabricated using partial transparent Si wafer and the current-voltage of the devices were tested. The front surface efficiency obtained for both partial transparent bifacial solar cells were 4.36% and 5.59%, while rear surface achieved 1.23% and 1.16%. Fabricated conventional bifacial solar cell has an efficiency of 2.39% for front and 0.64% for rear. The surface modification enhanced the efficiency due to the photon path length transmission to rear surfaces, micro-hole’s dimension and optical absorption in the near-infrared region.

The Risk Monitoring of the Financial Ecological Environment in Chinese Outward Foreign Direct Investment Based on a Complex Network

Aiming at the risk problem of financial ecological environment in outward foreign direct investment (OFDI), this paper constructs a risk monitoring model of the financial ecological environment based on complex network theory, and analyzes the general laws of financial risk evolution in Chinese OFDI by using data from 2008 to 2017 in 20 countries. First, the key risk factors are found through centrality analysis, then the correlation between risk indicators is obtained by cohesive subgroup analysis. Finally, we calculate network density, clustering coefficient and global efficiency to explore the time-spatial laws of the financial risk evolution in OFDI are obtained. At the same time, Kruskal’s algorithm is used to generate the minimum spanning tree (MST), and the change trend of risk transmission path is obtained. The results show that the following four risk indicators: M2/GDP, foreign exchange reserve, stock exchange turnover rate, total government debt as a percentage of GDP play an important role in the whole risk network and are the key nodes of risk evolution. The internal financial risks in Pakistan, the United States, Israel and Poland are more complex and highly transmissible. The risk transmission path based on MST shows that Australia and Bulgaria play an important role in risk transmission, and the length of risk transmission path has an overall upward trend. The conclusions of this study have guiding significance for overseas investment companies to prevent investment risks and ensure their sustainable development overseas.

Visible-to-near-infrared optical properties of protein, lipid and carbohydrate in both solid and solution state at room temperature

An accurate knowledge of optical constant of protein, lipid and carbohydrate is important for analyzing radiative transport between cells. However, it is difficult to measure precisely the optical constant of these elements due to the complicated sample-making and the limitation of traditional measurement method. In this work, the double optical pathlength transmission method and the ellipsometry method (DOPTM-EM) were used to obtain the optical constants of protein, lipid and carbohydrate of Chlorella sp. (both solid-state and solution-state), solution-state egg protein and solution-state sucrose in the spectral range 300-1700 nm. Isolations of protein, lipid and carbohydrate from Chlorella sp. were conducted. For different types and states of protein, lipid and carbohydrate, the optical constants of these samples are different from each other. The refractive indices of protein and carbohydrate have obvious relationship with the existing state. A significant difference of absorption indices can be observed between the solution-state protein of Chlorella sp. and the egg protein. It is indicated that the amino acids composition of solution-state protein of Chlorella sp. differs from the egg protein. The absorption indices of solution-state carbohydrate do not agree with the solution-state sucrose. For the sake of applications, the fitted formula of the refractive index as a function of wavelength is presented.

Optimum Sample Thickness for Trace Analyte Detection with Field-Resolved Infrared Spectroscopy

The strong absorption of liquid water in the infrared (IR) molecular fingerprint region constitutes a challenge for applications of vibrational spectroscopy in chemistry, biology, and medicine. While high-power IR laser sources enable the penetration of ever thicker aqueous samples, thereby mitigating the detrimental effects of strong attenuation on detection sensitivity, a basic advantage of heterodyne-measurement-based methods has—to the best of our knowledge—not been harnessed in broadband IR measurements to date. Here, employing field-resolved spectroscopy (FRS), we demonstrate in theory and experiment fundamental advantages of techniques whose signal-to-noise ratio (SNR) scales linearly with the electric field over those whose SNR scales linearly with radiation intensity, including conventional Fourier-transform infrared (FTIR) and direct absorption spectroscopy. Field-scaling brings about two major improvements. First, it squares the measurement dynamic range. Second, we show that the optimum interaction length with samples for SNR-maximized measurements is twice the value usually considered to be optimum for FTIR devices. In order to take full advantage of these properties, the measurement must not be significantly affected by technical noise, such as intensity fluctuations, which are common for high-power sources. Recently, it has been shown that subcycle, nonlinear gating of the molecular fingerprint signal renders FRS robust against intensity noise. Here, we quantitatively demonstrate this advantage of FRS for thick aqueous samples. We report sub-μg/mL detection sensitivities for transmission path lengths up to 80 μm and a limit of detection in the lower μg/mL range for transmission paths as long as 200 μm.

Comprehensive optical and electrical characterization and evaluation of organic light-emitting diodes for visible light communication

In recent years, we have seen an increased use of organic light emitting diodes (OLEDs) for illumination in indoor environments due to the softer light compared with the conventional inorganic LEDs. In addition, OLEDs have been reported in visible light communication (VLC) systems, specifically for applications with lower data rates such as information boards, camera communications and positioning. However, OLEDs need extensive electrical and optical characterization if they are going to be fully exploited in VLC. This paper investigates characteristics of a range of flexible and rigid OLEDs and compares them with inorganic LEDs. We show that, OLEDs have highly linear power-current characteristics, and compared with rigid OLEDs with beam patterns closely matching Lambertian profile, the flexible OLED's radiation pattern is wider than Lambertian. Based on the measured experimental data, a new expression for the OLED's beam pattern, which follows the 3-term Gaussian profile, is proposed. Moreover, we show that using larger size OLED in VLC links offers improved bit error rate performance over a wide tilting angle up to 80° and a transmission path length up to 60 cm.

Compensation of Multicore Fiber Skew Effects for Radio Over Fiber mmWave Antenna Beamforming

In 5G networks, a Radio over Fiber architecture utilizing multicore fibers can be adopted for the transmission of mmwave signals feeding phased array antennas. The mmwave signals undergo phase shifts imposed by optical true time delay networks, to provide squint free beams. Multicore fibers are used to transfer the phase shifted optical signals. However, the intercore static skew of these fibers, if not compensated, distorts the radiation pattern. We propose an efficient method to compensate the differential delays, without full equalization of the transmission path lengths, reducing the power loss and complexity. Statistical analysis shows that regardless of the skew distribution, the frequency response can be estimated with respect to the rms skew delays. Simulation analysis of the complete Radio over Fiber and RF link validates the method.

Noninvasive simultaneous monitoring of pH and depth using surface‐enhanced deep Raman spectroscopy

AbstractHere we demonstrate the simultaneous recovery of multiplexed physical information of surface‐enhanced Raman scattering (SERS) nanoparticles (pH and depth) using deep Raman spectroscopy. As has been shown previously and in accordance with theory, inelastically scattered photons arising from spectral peaks that are suitably separated can exhibit different optical properties in the media through which they travel. These differences can impact the relative intensities of the Raman peaks as a function of the transmission path length; thereby, the depth of signal generation is inherently encoded in the spectra; assuming the target is clustered at a single depth or location, its depth can be readily determined. Moreover, Raman spectroscopy is very sensitive to chemistry of a sample, and changes in pH are observed not only as changes in peak intensity through relevant protonation and deprotonation but also as shifts in spectral features. Here, we show it is possible to precisely predict the depth (root‐mean‐square error [RMSE] 5 %) of SERS nanoparticles in scattering media (0.5% intralipid) while also being able to noninvasively monitor simultaneously the pH levels (RMSE ~0.2 pH units) of the media surrounding the nanoparticles. This is important as it demonstrates that nanoparticles can be used to report on multiple physical properties including their depth. This opens avenues for a range of new applications including the noninvasive diagnosis and localisation of cancer lesions in clinical environment in vivo.

Complex refractive indices measurements of polymers in visible and near-infrared bands.

The complex refractive indices of polymers have important applications in the analysis of their components and the study of radiation endothermic mechanisms. Since these materials have high transmittance in the visible to near-infrared ranges, it is difficult to accurately measure their complex refractive indices. At present, the data for complex refractive indices of polymers are seriously lacking, which greatly limits the applications of these materials in the field of thermal radiation. In this work, spectroscopic ellipsometry (SE) combined with the ray tracing method (RTM) is used to measure the complex refractive indices of five polymers, polydimethylsiloxane, poly(methyl methacrylate) (PMMA), polycarbonate, polystyrene, and polyethylene terephthalate, in the spectral range of 0.4-2 µm. The double optical pathlength transmission method (DOPTM) is used to measure the complex refractive indices of three polymers, PMMA, polyvinyl chloride, and polyetherimide, in the 0.4-2 µm range. The complex refractive index of PMMA measured by the DOPTM almost coincides with the data measured by SE combined with the RTM. The results show that the trends of the complex refractive indices spectra for the seven polymers in the 0.4-2 µm range are similar. This work makes up for the lack of complex refractive indices in the 0.4-2 µm range for these seven materials and points out the direction for accurate measurements of the complex refractive indices of polymers with weak absorption.

Temperature-dependent optical constants of highly transparent solids determined by the combined double optical pathlength transmission-ellipsometry method.

The optical constants of five highly transparent substrates (polycrystalline BaF2, CaF2, MgF2, ZnSe, and ZnS) were experimentally determined based on a combined technique using both the double optical pathlength transmission method and the ellipsometry method within temperature range 20°C-350°C in the ultraviolet-infrared region (0.2-20μm). The results show that the refractive index spectra of polycrystalline BaF2, CaF2, and MgF2 are similar, but differ from that of polycrystalline ZnSe and ZnS. The thermo-optic coefficient of these highly transparent substrates increases with increasing temperature. The absorption indices show a significant temperature-dependent behavior, which increases with increasing temperature from 20°C to 350°C over the transparent region. For the sake of application, the fitted formulas of the refractive index of the five highly transparent substrates as a function of wavelength and temperature are presented.

Stiffness Degradation and Damping Ratio of Sand-Gravel Mixtures Under Saturated State

The aim of this research was to explain the effects of gravel content using the intergrain state concept, relative density and confining pressure on G max, G/G max–γ and D–γ curves and the reference strain (γ r). A total of 45 G–γ and D–γ curves derived from resonant column testing and cyclic triaxial testing along with S-wave velocity measurements obtained using the bender element technique were assessed. The test specimens were prepared with different gravel contents (0, 30, 50, 75 and 100%) under different relative densities (10, 30 and 60%) and mean effective confining pressures (100, 300 and 600 kPa). Comparison of the G max results of the resonant column and bender element tests was also carried out. The desired excitation frequencies and ratios λ/D 50 and d/λ (where λ is wavelength, d is transmission path length and D 50 is average particle size) were determined based on the bender element tests results. The test results were used to evaluate the empirical equation for prediction of G max and to develop a new prediction equation with which to estimate γ r. The results of the tests were used to validate previous models and empirical curves.

Noninvasive Determination of Depth in Transmission Raman Spectroscopy in Turbid Media Based on Sample Differential Transmittance.

Here we propose a simple noninvasive approach to determine the depth of a buried object using transmission Raman spectroscopy. In accordance with theory, the photons arising from spectral peaks that are suitably separated will be subjected to different optical properties in the media through which they travel. These differences can impact the relative intensities of Raman peaks as a function of the transmission path length, thereby the depth of signal generation is inherently encoded in the spectra. In a proof-of-concept study, through only external calibrations, it was possible to accurately predict the depth of Polytetrafluoroethylene (PTFE) layer purely on the basis of relative intensity of two peaks in a predominantly absorbing solution Indian ink (0.1 μL/mL; RMSE 0.42 mm) and a scattering solution (RMSE 0.50 mm). This simple approach offers the possibility to noninvasively identify the depth of a buried object, such as breast calcifications, using simple transmission measurement geometries for the first time.

Experimental demonstration of indoor interfered visible light communication system employing successive interference cancellation

Multipath interference induced power fading occurs when the transmission path lengths from the light emitting diodes to a single receiver are different in a visible light communication system. To solve this problem, we apply a QR-decomposition-based channel equalizer (QR-CE) to achieve successive interference cancellation for a discrete Fourier transform spreading (DFT-S) orthogonal frequency division multiplexing (OFDM) signal. We experimentally demonstrate a 200 Mb/s DFT-S OFDM over a 2 m free-space transmission. The experimental results show that a DFT-S OFDM with QR-CE attains much better bit error rate performance than a DFT-S OFDM with conventional CEs. The impacts of several parameters on a QR-CE are also investigated.

Features of the Asynchronous Correlation between the China Coal Price Index and Coal Mining Accidental Deaths.

The features of the asynchronous correlation between accident indices and the factors that influence accidents can provide an effective reference for warnings of coal mining accidents. However, what are the features of this correlation? To answer this question, data from the China coal price index and the number of deaths from coal mining accidents were selected as the sample data. The fluctuation modes of the asynchronous correlation between the two data sets were defined according to the asynchronous correlation coefficients, symbolization, and sliding windows. We then built several directed and weighted network models, within which the fluctuation modes and the transformations between modes were represented by nodes and edges. Then, the features of the asynchronous correlation between these two variables could be studied from a perspective of network topology. We found that the correlation between the price index and the accidental deaths was asynchronous and fluctuating. Certain aspects, such as the key fluctuation modes, the subgroups characteristics, the transmission medium, the periodicity and transmission path length in the network, were analyzed by using complex network theory, analytical methods and spectral analysis method. These results provide a scientific reference for generating warnings for coal mining accidents based on economic indices.