Features Of Spectra Research Articles

Easy and effective! Data augmentation for knowledge-aware dialogue generation via multi-perspective sentences interaction

In recent years, knowledge-based dialogue generation has garnered significant attention due to its capacity to produce informative and coherent responses through the integration of external knowledge into models. However, obtaining high-quality knowledge that aligns with the dialogue content poses a considerable challenge, necessitating substantial time and resources. To tackle the issue of limited dialogue data, a majority of research endeavors concentrate on data augmentation to augment the volume of training data. Regrettably, these methods overlook knowledge augmentation, leading to a restricted diversity in input data and yielding enhancements solely in specific metrics. Real-world conversations exhibit a spectrum of characteristics, including repetitions, reversals, and interruptions, demanding a heightened level of data diversity. In this study, we introduce a straightforward yet effective data augmentation technique known as Multi-perspective Sentence Interaction to bolster the connections among sentences from varied viewpoints. Through an examination of target responses from multiple dialogue perspectives, we enhance our comprehension of the relationships between dialogue sentences, thereby facilitating the expansion of knowledge-based dialogue data. Through experiments conducted on various knowledge-based dialogue datasets and utilizing different models, our findings illustrate a notable enhancement in the quality of model generation facilitated by our method. Specifically, we observed a 3.5% enhancement in reply accuracy and a 0.1506 increase in diversity (DIST-2). Moreover, there was a substantial improvement in knowledge selection accuracy by 19.04% and a reduction in model perplexity by 31.48%.

Experimental investigation of OH* emission spectrum characteristics and transient ignition dynamics in methane and coal dust mixtures explosions

Combustible gases, dusts and their mixtures are widely present in human production and life，and the fire and explosion disasters caused by them pose a serious threat to the field of energy security applications. Studying the ignition process of mixtures is essential for disaster risk assessment and safety protection. In this work, the explosion characteristics and OH* emission spectra of the mixtures were experimentally tested by varying the fuel equivalence ratio ( ER ≈ 0.79 ∼ 1.71), and the evolution of the transient flow field structure during the ignition process was quantitatively analyzed using the schlieren image velocimetry method. The results indicate that the emission spectrum of OH* is closely correlated with the maximum explosion pressure, and the spectral intensity of OH* at 306.4 nm is consistent with the maximum rate of explosion pressure rise. The flow field during the ignition process of the mixtures shows that a small amount of coal dust (concentration≤30 g/m3) can significantly promote flame acceleration and instability as the methane concentration is in lean combustion or stoichiometric ratio. However, when the concentration of coal dust increases (concentration≥40 g/m3), coal dust will suppress flame acceleration and instability. For methane concentration in fuel-rich combustion state, coal dust always suppresses flame acceleration and instability. The experimental results contribute to a further understanding of gas and coal dust mixed explosions and provide a verification database for the construction of chemical kinetic mechanisms.

Analyzing the spectrum characteristics of a double-grating transmission scheme

In this paper, the spectral characteristics formed by a double-grating transmission scheme are discussed based on the scalar diffraction theory. First, considering two different grating periods, the angular spectrum at the back of the second grating is obtained. Then, the spectral characteristics are discussed with three different periodic conditions, while it is proved that the spatial distribution and spacing of the spectrum are absolutely determined by the grating constants and angles. The theoretical results manifest that the spatial distribution range of the spectrum becomes larger as the angle increases, unlike the spectral points, which are distributed on a single line when the grating lines of the two gratings are parallel. Finally, for the sake of proving that our theoretical analysis is correct and reasonable, three sets of experiments are conducted with three different combinations of Ronchi gratings. As expected, the experimental and theoretical results are in perfect agreement. In a word, the involved results could be useful for expanding the application of moiré deflectometry.

Simultaneous Quantitation of Persulfides, Biothiols, and Hydrogen Sulfide through Sulfur Exchange Reaction with Trityl Spin Probes.

Reactive sulfur species (RSS) including persulfides (RSSHs), biothiols, and hydrogen sulfide (H2S) are key regulators in various physiological processes. To better understand the symbiotic relationship and interconversion of these RSS, it is highly desirable but challenging to develop analytical techniques that are capable of detecting and quantifying them. Herein, we report the rational design and synthesis of novel trityl-radical-based electron paramagnetic resonance (EPR) probes dubbed CT02-TNB and OX-TNB. CT02-TNB underwent fast sulfur exchange reactions with two reactive RSSHs (PS1 and PS2) which were released from their corresponding donors PSD1 and PSD2 to afford the specific conjugates. The resulting conjugates exhibit characteristic EPR spectra, thus enabling discriminative detection and quantitation of the two RSSHs. Moreover, CT02-TNB showed good response toward other RSS including glutathione (GSH), cysteine (Cys), H2S, and sulfite as well. Importantly, based on the updated EPR spectral simulation program, simultaneous quantitation of multiple RSS (e.g., PS1/GSH/Cys or PS1/GSH/H2S) by CT02-TNB was also achieved. Finally, the levels of released PS1 from PSD1 and endogenous GSH in isolated mouse livers were measured by the hydrophilic OX-TNB. This work represents the first study achieving discriminative and quantitative detection of different persulfides and other RSS by a spectroscopic method.

Wetting and emulsification properties of cellulose nanocrystals modified with tannic acid and alkyl cellulose derivatives

HypothesisCellulose nanocrystals (CNCs) are sustainable rod-like nanoparticles that can be used to stabilize oil-in-water emulsions and can create hydrophilic coatings. Modifying the surface of CNCs can improve emulsion properties and allow for adjustable wettability. ExperimentsThis study explores the improvement of Pickering emulsion properties for various oils and the adjustability of coated surfaces through the physical modification of CNCs, without chemical functionalization. Bio-based additives, including antioxidant tannic acid (TA), methyl cellulose (MC), and ethyl cellulose (EC) were used as surface modifiers. The identification of optimal formulations involved varying the weight fraction of the alkyl cellulose derivatives. FindingsThe findings suggest that, akin to pure CNCs, Pickering emulsions stabilized by TA and/or MC-modified CNCs demonstrate comparably high stability. The introduction of MC at a low weight fraction enhances hydrophilicity, and AFM analysis reveals smooth surfaces, mitigating the potential influence of roughness. In contrast, EC-modified CNCs result in less stable emulsions but exhibit more hydrophobic surfaces. This translates to a broad spectrum of characteristics, ranging from quasi-superhydrophilic to nearly hydrophobic (with contact angles spanning from below 11° up to 68°), all controllable through a straightforward physical coating process. This facile preparation of coated CNCs provides a versatile approach to customizing the wetting and emulsification properties of nanomaterials.

The Influence of Structure Optimization on Vortex Suppression and Energy Dissipation in the Draft Tube of Francis Turbine

Under partial load operating conditions, vortex rope generation in the draft tube of a Francis turbine is considered one of the main reasons for hydro unit vibration. In this paper, a Francis turbine HLA551-LJ-43 in the laboratory was taken as a prototype. Numerical simulations of the entire flow passage were carried out. Four different hydro-turbines were chosen to analyze the effect of vortex suppression, which were named the prototype turbine (N-J), the turbine with J-grooves installed on its conical section (W-J), the one with extending runner cone (C), and the one that considered the J-grooves and the extending runner cone at the same time (J+C). Under the part load conditions in which the vortex rope is easily generated (0.4–0.8 times design flow QBEP), the spectrum characteristics of pressure fluctuation, the morphology of vortex rope, and the energy dissipation based on the entropy production theory in the draft tube were studied. The results show that the three optimized structures W-J, C, and J+C could reduce the pressure pulsation in the conical section of the draft tube, weaken the eccentricity of the vortex rope, and decrease the energy losses in the runner and draft tube. It is worth mentioning that the turbine with a J+C optimized structure had the most potent effect on vortex suppression and energy dissipation. Primarily when operating in deep partial load (DPL) conditions, the efficiency of the turbine with a J+C optimized structure was increased by 13.7% compared to the prototype turbine, and the main frequency amplitude of the pressure pulsation in the draft tube was reduced to 32% of the prototype.

Identifying the Vertical Stratification of Sediment Samples by Visible and Near-Infrared Spectroscopy

Vertical stratification in marine sediment profiles indicates physical and chemical sedimentary processes and, thus, is the first step in sedimentary research and in studying their relationship with global climate change. Traditional technologies for studying vertical stratification have low efficiency; thus, new technologies are highly needed. Recently, visible and near-infrared spectroscopy (VNIR) has been explored to rapidly determine sediment parameters, such as clay content, particle size, total carbon (TC), total nitrogen (TN), and so on. Here, we explored vertical stratification in a sediment column in the South China Sea using VNIR. The sediment column was 160 cm and divided into 160 samples by 1 cm intervals. All samples were classified into three layers by depth, that is, 0–50 cm (the upper layer), 50–100 cm (the middle layer), and 100–160 cm (the bottom layer). Concentrations of TC and TN in each sample were measured by Elementa Vario EL III. Visible and near-infrared reflectance spectra of each sample were collected by Agilent Cary 5000. A global model and several classification models for vertical stratification in sediments were established by a Support Vector Machine (SVM) after the characteristic spectra were identified using Competitive Adaptive Reweighted Sampling. In the classification models, K-means clustering and Density Peak Clustering (DPC) were employed as the unsupervised clustering algorithms. The results showed that the stratification was successful by VNIR, especially when using the combination of unsupervised clustering and machine learning algorithms. The correct classification rate (CCR) was much higher in the classification models than in the global model. And the classification models had a higher CCR using K-means combined with SVM (94.8%) and using DPC combined with SVM (96.0%). The higher CCR might be derived from the chemical classification. Indeed, similar results were also found in the chemical stratification. This study provided a theoretical basis for the rapid and synchronous measurement of chemical and physical parameters in sediment profiles by VNIR.

Exploring the viability of thermally robust β-BaB2O4: Dy3+ through FIR based polynomial approach for advanced temperature sensing and WLED applications

In this present work, we have explored the optical, structural, and thermal sensing properties of novel β-BaB2O4: xDy3+ (x = 1, 2, 3, 4, and 5 mol%) phosphors prepared using the solid-state reaction method. The optimization of the phosphors was achieved by using the characteristic emission spectra of Dy³⁺ ions. A thorough investigation was conducted into the various mechanisms contributing to concentration quenching, including cross-relaxation pathways, multipole-multipole interactions, and non-radiative energy transfer processes. Using the diffused reflectance spectra, significant parameters including optical band gap, nephelauxetic ratio, bonding parameter, and refractive index were evaluated. Temperature-dependent optical properties revealed a very high quenching temperature of 492.7 K. Using the florescent intensity ratio (FIR) with polynomial fit from 2nd to 5th order, the highest absolute sensitivity was obtained as 0.0472 K−1 at 483 K, and the highest relative sensitivity of 0.3922 % K−1 at 303 . Finally, the optimized phosphor exhibited exceptional thermal stability up to 500˚C with nearly 1 wt% of loss.

Research on the effect of CO2 and H2O on NO reduction of biomass char by the equivalent characteristic spectrum method via an on-line mass spectrometer

Despite extensive experimental studies on NO reduction by biomass char, the impact of high concentrations of CO2 and H2O on the NO-char reaction remains insufficiently understood. This study investigates the effects of CO2, H2O, and CO2+H2O atmospheres on NO reduction by biomass char in a micro-fluidized bed (MFB). Experiments were conducted at 900 °C, with CO2 concentrations ranging from 20 % to 80 % and H2O concentrations from 10 % to 40 %. The results show that increasing concentrations of CO2 and H2O accelerate the NO reduction rate. However, under high CO2 and H2O concentrations, both the maximum NO reduction efficiency and the mass consumption of nitrogen decrease. In a CO2 atmosphere, nearly all nitrogen from NO converts to N2, but this conversion efficiency declines in the presence of H2O. When both CO2 and H2O are present, H2O predominantly governs the NO consumption rate. Additionally, the apparent activation energy for NO reduction is higher in an H2O atmosphere compared to a CO2 atmosphere at similar concentrations.

Novel ionic liquid systems based on three-nitro phenoxide: Spectroscopic and electronic characterization using theoretical and experimental study

After extensive computations, novel trinitro compounds, triethyl ammonium 2,4,6-trinitro phenoxide (TEA-TNP) and tetramethyl guanidinium 2,4,6-trinitro phenoxide (TMG-TNP), are designed, synthesized, and identified. The Geometrical parameters, electronic properties, and spectroscopic analysis have been investigated by comparison of theoretical and experimental methods. Spectrum features that include IR and Raman have been calculated, and 1H and 13C NMR spectra are compared to experimental data. Electronic analysis has been investigated through NLO, FMO, UV-Vis, NBO, and MEP calculations. B3LYP/6-311++G(d,p) is highly successful and dependable for predicting ionic liquid stability, electrical characteristics, and spectroscopy. Both TEA-TNP and TMG-TNP are introduced as suitable candidates for NLO material. TMG-TNP with greater nucleophilicity (N) is a noncorrosive lubricant additive that reduces friction and wear for tribological performance.

Denoising Medium Resolution Stellar Spectra With Neural Networks

ABSTRACTWe trained denoiser autoencoding neural networks on medium resolution simulated optical spectra of late‐type stars to demonstrate that the reconstruction of the original flux is possible at a typical relative error of a fraction of a percent down to a typical signal‐to‐noise ratio of per pixel. We show that relatively simple networks are capable of learning the characteristics of stellar spectra while still flexible enough to adapt to different values of extinction and fluxing imperfections that modifies the overall shape of the continuum, as well as to different values of Doppler shift. Denoised spectra can be used to find initial values for traditional stellar template fitting algorithms and—since evaluation of pretrained neural networks is significantly faster than traditional template fitting—denoiser networks can be useful when a fast analysis of the noisy spectrum is necessary, for example during observations, between individual exposures.

Intrinsic process for upconversion photoluminescence via K -momentum–phonon coupling in carbon nanotubes

We investigate the intrinsic microscopic mechanism of photon upconversion in air-suspended single-walled carbon nanotubes through photoluminescence and upconversion photoluminescence spectroscopy. Nearly linear excitation power dependence of upconversion photoluminescence intensity is observed, indicating a one-photon process as the underlying mechanism. In addition, we find a strongly anisotropic response to the excitation polarization, which reflects the intrinsic nature of the upconversion process. In upconversion photoluminescence excitation spectra, three peaks are observed, which are similar to photoluminescence sidebands of the K-momentum dark singlet exciton. The features in the upconversion photoluminescence excitation spectra are well reproduced by our second-order exciton-phonon interaction model, enabling the determination of phonon energies and relative amplitudes. The analysis reveals that the upconversion photoluminescence can be described as a reverse process of the sideband emission linked to the K-momentum phonon modes. The validity of our model is further reinforced by temperature-dependent upconversion photoluminescence excitation measurements reflecting variations in the phonon population. Our findings underscore the pivotal role of the resonant exciton-phonon coupling in pristine carbon nanotubes and present potential for advanced optothermal technologies by engineering the excitation pathways. Published by the American Physical Society 2024

Spectroscopic study of Mo97, Mo99 , and Mo101

Excited states of the molybdenum isotopes Mo4297,99,101 have been populated in two experiments which used fusion-fission and binary grazing reactions to populate yrast states of the nuclei of interest. In the first experiment, the GASP array of escape-suppressed Ge detectors was used to detect γ rays from fusion-fission products initiated by the interaction of a 230-MeV beam of S36 ions with a thick target of Yb176. In the multinucleon transfer experiment, a 530-MeV beam of Zr96 ions was incident on a thin Sn124 target; projectile-like ejectiles were detected and identified using the PRISMA magnetic spectrometer and their associated γ rays were detected using the CLARA array of escape-suppressed Ge detectors. In Mo99, the previously known positive-parity νd5/2 decay sequence was extended to spin (25/2+) while, in Mo101, a similar, but hitherto unobserved νg7/2 positive-parity decay sequence was established to spin (27/2+). In Mo99 and in Mo101, previously observed νh11/2 negative-parity decay sequences were also observed to spin 27/2−. Although the observed decay sequences in Mo97 have not been extended beyond the results of earlier work, a disagreement in the published level structure of the h11/2 band has been resolved. The observed positive-parity decay sequences have been compared with the results of state-of-the-art shell-model calculations; the general features of the energy spectrum of excited states of Mo97, Mo99, and Mo101 are reproduced, but not in detail. The experimental energies of the negative-parity states of Mo99 and Mo101 are reasonably well reproduced in particle-rotor (PRM) calculations. For Mo97, better agreement with the high-spin states was obtained when the core in the PRM calculations was treated in a variable moment of inertia approach. For the νh11/2 negative-parity decay sequences of the three isotopes studied here, model-dependent evidence is presented for nuclear shape changes with increasing neutron number. Published by the American Physical Society 2024

Environmentally friendly, high near-infrared reflection green pigments for thermal insulation

In this paper, TiO2 and MgAl-LDHs were coated on yellow pigment hydroxyl iron oxide (FeOOH) with sol-gel and hydrothermal synthesis method respectively to prepare loaded yellow pigment (FT8M0.25). Then, phthalocyanine blue (CuPc) was combined with FT8M0.25 to prepare composite green pigment (FT8M0.25Px). The results indicate the FT8M0.25Px has the structural characteristics of hydrotalcites and CuPc. The surface of FeOOH pigment has a clear TiO2 coating layer and MgAl-LDHs flake structure. KPFM analysis indicate that there is electron transfer between the interfaces of pigments. According to the analysis of color performance and near-infrared reflectance (NIR), the FT8M0.25P0.13 (a*=-12.98) is greener than that of Cr2O3 (a*=-6.65). The NIR of FT8M0.25P0.13 is as high as 73.54 %. The visible light absorption spectrum characteristics determine the color of the pigments, and there is electron transfer between the interfaces of each group. The formation of multi-level interfaces and the resulting multiple light reflections increase the reflectivity of the pigment. The developed coating achieved a considerable temperature difference of 20 °C before and after the coating surface with excellent photostability and reusability, which makes it possible for pigments to replace chromium containing pigments and be used as energy-saving cold pigments.

Lipoprotein glomerulopathy: what is known? Literature review

The review is devoted to the important problem of contemporary nephrology — lipoprotein glomerulopathy (LPG), a rare glomerular disorder leading to nephrotic syndrome and/or chronic kidney failure (CKF). The article highlights the primary genetic defect in LPG associated with heterozygous mutations of the apolipoprotein E (ApoE) gene in the low‑density lipoprotein (LDL) binding site with the corresponding receptor, which increases the affinity of mutant ApoE‑containing lipoproteins to the glomerular capillary wall. The article presents data from population‑based studies on the prevalence of LPG and current understanding of its pathogenesis, in particular, the main pathogenetic link — damage to the structure and function of ApoE due to heterozygous mutations of the ApoE gene. The participation of ApoE‑containing lipoproteins, which include ApoE isoforms, in the formation of glomerular deposits, lipoprotein thrombi in the lumen of glomerular capillaries, as well as the role of macrophages in the pathogenesis of renal lipidosis is considered. Histological picture typical for LPG, intraglomerular and extrarenal factors of its development, and features of serum lipid spectrum accompanying the clinical course of LPG are described. Diagnostic criteria of LPG, clinical manifestations of this glomerular disorder, prognosis in LPG, its complications and some co-morbid states associated with LPG are given. Special attention is paid for the treatment of LPG, without which the disease is progressing to a terminal CKF. Some possibilities of contemporary lipid lowering agents (fibrates, nicotinic acid derivates, statins, monoclonal antibodies to apolipoprotein CIII) in correction of lipid disorders associated with LPG are discussed. Some perspective agents that could be applied in patients with LPG (inhibitors of natrium-dependent glucose co-transporter 2, antioxidants, anticonvulsant topiramate) after special trials are enumerated. Some attention is paid to other treatment measures in LPG, such as LDL-apheresis with heparin‑induced extracorporal precipitation, staphylococcal protein-A immunoadsorption therapy, and renal transplantation. Necessity is emphasized of further experimental and clinical studies that will allow to enlarge updated ideas about the etiology and pathogenesis of LPG, improve its diagnostics and treatment efficacy.

Exploring Riboflavin Quantification in Honey via Spectrofluorimetry: A Statistical Examination of Influential Extrinsic Variables

Background: The present study is focused on the collection of honey samples from the different geographical and climatic conditions of Khyber Pakhtunkhwa and analyzing them for the determination of riboflavin. Quantification of riboflavin, being natively fluorescent, was accomplished using spectrofluorimetric method. Riboflavin has characteristic fluorescence spectra with maximum excitation at 464 nm followed by an emission peak at 525 nm. Method: The procedure followed in this work comprised the construction of a calibration curve by plotting the fluorescence intensity of a series of riboflavin solutions versus concentration. This curve was used for the quantification of riboflavin in the collected honey samples. The effect of several external factors such as the altitude of the sampling area, type of honey bee, type of flowers from which the nectar was collected, and sampling season on the concentration of riboflavin in the honey samples was statistically evaluated. Results and Discussion: It was concluded that the samples collected from lower altitudes have high concentrations (1.156±0.08 μg g-1) of riboflavin. Similarly, the samples collected in autumn were found to have a maximum average riboflavin concentration of 1.37±0.06 μg g-1, which was higher in comparison to the samples collected in other seasons of the year. Likewise, the effect of flora on the concentration of riboflavin was also investigated and it was found that honey samples collected from areas where the nectar was collected from Ziziphus contains maximum riboflavin concentration averaged at 1.383±0.1 μg g-1. Conclusion: Based on the size of the honey bees, the samples collected from hives of small honey bees were found to have a maximum riboflavin concentration of 1.176±0.07 μg g-1. This study suggests that besides the studied vitamin, the rest of the vitamins and other nutritional components may vary in the honey samples depending upon external factors. conclusion: It was concluded that the samples collected from lower altitudes have high concentration (1.156±0.08 μg g-1) of riboflavin. Similarly, the samples collected in autumn were found to have a with a maximum average riboflavin concentration of 1.37±0.06 μg g-1, which was higher in comparison to the samples collected in other seasons of the year. Likewise, the effect of flora on the concentration of riboflavin was also investigated and it was found that honey samples collected from areas where the nectar was collected from Ziziphus contains maximum riboflavin concentration averaged at 1.383±0.1 μg g-1. Based on the size of the honey bees the samples collected from hives of small honey bees were found to have maximum riboflavin concentration of 1.176±0.07 μg g-1. This study suggests that beside the studied vitamin, the rest of the vitamins and other nutritional components may vary in the honey samples depending upon external factors.

The Influence of Thickness and Spectral Properties of Green Color-Emitting Polymer Thin Films on Their Implementation in Wearable PLED Applications.

A systematic investigation of optical, electrochemical, photophysical, and electrooptical properties of printable green color-emitting polymer (poly(9,9-dioctylfluorene-alt-bithiophene)) (F8T2) and spiro-copolymer (SPG-01T) was conducted to explore their potentiality as an emissive layer for wearable polymer light-emitting diode (PLED) applications. We compared the two photoactive polymers in terms of their spectral characteristics and color purity, as these are the most critical factors for wearable lighting sources and optical sensors. Low-cost, solution-based methods and facile architecture were applied to produce rigid and flexible light-emitting devices with high luminance efficiencies. Emission bandwidths, color coordinates, operational characteristics, and luminance were also derived to evaluate the device's stability. The tuning of emission's spectral features by layer thickness variation was realized and was correlated with the interplay between H-aggregates and J-aggregates formations for both conjugated polymers. Finally, we applied the functional green light-emitting PLED devices based on the two studied materials for the detection of Rhodamine 6G. It was determined that the optical detection of the R6G photoluminescence is heavily influenced by the emission spectrum characteristics of the PLED and changes in the thickness of the active layer.

Stretchable kirigami mechanical metamaterial with tunable dual electromagnetically induced transparency resonances

Kirigami, i.e. paper cutting is nowadays widely investigated to design the mechanical structure that can be transformed with unique and programmable performances. When it is transformed, the components of the kirigami are also reconfigured and then provide tunable polarization-sensitive electromagnetic responses. In this study, we present a design of stretchable kirigami mechanical metamaterial (SKMM) with dual electromagnetically induced transparency (EIT) resonances. The proposed two designs of SKMM show two dual EIT resonances at 0.905 THz, 0.975 THz, and 0.449 THz, 0.558 THz, which can be switched to 0.964 THz, 1.042 THz and 0.433 THz, 0.532 THz by rotating kirigami cells in predestinated orientations, respectively. During the continuous modulations of transmission spectra by increasing the stretching force, the characteristics of resonant spectra maintain excellent with their corresponding averaged Q-factors as 33.19, 21.59 and 4.87, 17.31, respectively. The EIT resonances originating from the bright-bright mode could be explained with multipole scattering theory along with the three-dimensional schematic illustrations. These results prove the proposed SKMM possesses promising applications in slow light, optical data computing, quantum information technology, and sensing fields.

Enhanced breast tumor localization with DRA antenna backscattering and GPR algorithm in microwave imaging

With the rapid rate of increasing breast cancer cases across the globe and restrictions of existing early stage detection techniques, microwave imaging based cancer and malignant cell diagnosing methodology is finding its way. Microwave imaging technology has higher accuracy of detection in the variation of tissue properties. In this article, a dielectric resonator based wide band antenna is designed and investigated for microwave imaging (MWI) of early breast cancer detection due to its improved accuracy. The designed antenna has compact size, broad frequency spectrum, high gain and broadside radiation characteristics. To attain the wider bandwidth from (6.5 GHz–12.5 GHz), two rectangular shaped dielectric slabs are used. Wide band microwave frequency band supports the high resolution images. A C-shaped defected ground structure is used to tune the impedance matching. Dielectric resonator based antenna has higher gain and reduces the squints in antenna impedance. Two-asymmetrical dielectric slabs contribute in the excitation of different resonating modes which in turn enhance the bandwidth. It also contributes to excite multiple resonance mode that in turn enhance the bandwidth. Antenna performance is first numerically and experimentally verified in free space. Then, simulation based performance is examined for the microwave imaging. Numerical phantom with equivalent tissue properties is designed with and without the tumor. Unhealthy cells have higher water percentage and larger dielectric constant as compared to healthy cells. It causes the different in the back scattered signal of antenna, which is analyzed to diagnose the tumor or cancer. Here, a maximum deviation of 16 dB is observed in the backscattered signal. Furthermore, surface of the breast tissue is scanned along the x-axis and y-axis at different angels. The collected signals are used to reconstruct the microwave image of the interior. Mean value data of backscattered signals is used to locate the existence of unhealthy cells and GPR algorithm is used to calculate the depth of a 4 mm tumor in breast tissue. Proposed structure has shown efficient performance for microwave imaging.

Multi-Scale Frequency-Adaptive-Network-Based Underwater Target Recognition

Due to the complexity of underwater environments, underwater target recognition based on radiated noise has always been challenging. This paper proposes a multi-scale frequency-adaptive network for underwater target recognition. Based on the different distribution densities of Mel filters in the low-frequency band, a three-channel improved Mel energy spectrum feature is designed first. Second, by combining a frequency-adaptive module, an attention mechanism, and a multi-scale fusion module, a multi-scale frequency-adaptive network is proposed to enhance the model’s learning ability. Then, the model training is optimized by introducing a time–frequency mask, a data augmentation strategy involving data confounding, and a focal loss function. Finally, systematic experiments were conducted based on the ShipsEar dataset. The results showed that the recognition accuracy for five categories reached 98.4%, and the accuracy for nine categories in fine-grained recognition was 88.6%. Compared with existing methods, the proposed multi-scale frequency-adaptive network for underwater target recognition has achieved significant performance improvement.