bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermoelectric power in high-temperature superconductors: Theory and experiment (Review article)
Authors: Stepanov V. B. , Kolesnichenko Yu. A. , Solovjov A. L.
Published: August 2023

A comprehensive review of theoretical models devoted to thermoelectric power (thermoEMF) in high-temperature superconductors (HTSCs), as well as relevant experimental works, has been carried out. It is shown that the modified two-band model with an additional temperature term provides the best fit for thermoEMF S(T) for YBa2Cu3O7–δ (model 4). However, all the models discussed, including model 4, do not match the experimental data S(T) at T < T*, where T* is the pseudogap (PG) opening temperature, which is much higher than the superconducting transition temperature Tc. This is due to the experimental fact that, at T < T*, both the resistivity ρ(T) and the density of charge carrier nf, the density of states at the Fermi level decrease, and Seebeck coefficient S(T) increases sharply, which indicates a rearrangement of the Fermi surface. Thus, the rearrangement of the Fermi surface with the appearance of PG is well established, at least in YBCO. In addition, three different types of behavior of S/T as a function of log T around the quantum critical point were observed at a normalized carrier density p = p* ≈ 0.16. Thus, three different modes of quantum criticality in YBCO were revealed at p ≈ p*, below which some order sets in HTSC, which causes the rearrangement of the Fermi surface.
Phase V−T diagrams of solid hydrocarbons. part III: Cyclic compounds
Authors: Konstantinov V. A. , Karachevtseva A. V. , Sagan V. V.
Published: August 2023

P−T and V−T phase diagrams of cyclic hydrocarbons, namely benzene (C6H6), cyclopentane (C5H10), thiophene (C4H4S), and tetrahydrofuran (C4H8O), were constructed using both literature and our experimental data obtained during the study of isochoric thermal conductivity in high-temperature phase. The V−T phase diagrams of cyclohexane (C6H12) and furan (C4H4O), presented earlier, were refined and supplemented with P−T diagrams. The possibility of constructing a phase diagram for cyclohexene (C6H10) is also discussed. The changes in molar volume during melting and the boundaries of the existence of high-temperature phases have been determined. The magnitudes of thermal pressure of cyclic hydrocarbons studied were obtained. Experimental values of dPm/dT on melting line were compared with those calculated by the Clapeyron-Clausius equation.
Experimental heat capacity of 1D chains of Xe atoms adsorbed in the grooves of c-SWCNTs bundles: Contributions of vibrations and spatial redistribution of atoms
Authors: Barabashko M. S. , Bagatskii M. I. , Dolbin A. V. , Sumarokov V. V.
Published: August 2023

In the temperature range of 2−75 K, the analysis and comparison were performed: (i) experimental CP,Xe(T) and theoretical CV,Xe(T) heat capacity of 1D chains of xenon atoms adsorbed in grooves on the outer surface of bundles of single-walled carbon nanotubes with closed ends (c-SWCNTs); (ii) the experimental heat capacity CP,Xe(T) and the experimental contribution to the radial thermal expansion of the c-SWNTs-Xe sample of Xe that adsorbed the grooves of c-SWCNTs [αXe(T)]. There is an anomaly near 60 K on the CP,Xe(T) and αXe(T) curves due to the contribution of the spatial redistribution of Xe atoms between the chains and the outer surface of c-SWNTs. It was found that the dependencies of CP,Xe(T) and αXe(T) are qualitatively similar below 60 K. The anomaly near 60 K in the CP,Xe(T) curve indicates the complete of fragmentation of 1D Xe atomic chains. The obtained result is important for understanding the kinetics of gas impurity sorption/desorption processes in c-SWNTs.
Nonadditive generalization of the Gentile statistics
Authors: Rovenchak Andrij
Published: August 2023

The Gentile statistics interpolates between the standard bosonic and fermionic statistics, allowing an intermediate maximum state occupation 1< M < ∞. A generalization of this statistics having the Gibbs factor es/T phenomenologically substituted with the nonadditive Tsallis q-exponential is analyzed. Depending on the values of the statistics parameter q, peculiarities of the thermodynamic functions are observed: for q > 1, a finite (nonzero) minimum temperature arises in the model, while for q < 1, the specific heat does not tend to zero at T → 0. These results are consistent with previously reported for a similar generalization of the fermionic statistics [A. Rovenchak and B. Sobko, Physica A534, 122098 (2019)]. Their relevance for modeling phenomena in real physical systems is briefly outlined.
Superconductivity of rare-earth borides Dy1–xErxRh3.8Ru0.2B4 (x = 0, 0.2, 0.4) and Dy0.6Y0.4Rh3.85Ru0.15B4
Authors: Terekhov A. V. , Yarovyi V. M. , Zolochevskii I. V. , Ishchenko L. O. , Khrystenko E. V.
Published: August 2023

The effect on the superconductivity of the partial replacement of one magnetic rare-earth element (Dy) by another (Er) in rhodium borides Dy1–xErxRh3.8Ru0.2B4 with x = 0, 0.2, 0.4 is studied. It was found that in Dy1–xErxRh3.8Ru0.2B4, with increasing Er content, the temperature of the superconducting transition increases significantly: from 3.7 K for x = 0 to 6 K for x = 0.4. It was demonstrated that the replacement of magnetic Er3+ with nonmagnetic Y3+ in the isostructural compounds Dy0.6Er0.4Rh3.8Ru0.2B4 (Tc ≈ 6 K) and Dy0.6Y0.4Rh3.85Ru0.15B4 (Tc ≈ 7 K) does not lead to a significant change in the temperature of the superconducting transition. The suppression of the superconducting state by the magnetism of rare-earth elements is not observed down to 1.5 K the lowest available temperature in the experiment.
Optical spectrum analyzers and typical applications in astronomy and remote sensing
Authors: Yan C. S. , Chen Y. W. , Yang H. M. , Ahokas E.
Published: August 2023

Scientists are increasingly relying on astronomical and remote sensing technologies to gain deeper insights into the Earth and the universe. In these fields, the optical spectrum analyzer (OSA) or spectrometer plays a pivotal role. This Review offers a comprehensive overview of the fundamental principles, key parameters, and applications of various branches of traditional OSAs, including prisms, gratings, interferometers, tunable filters, and reconstructive spectrometers. We specifically focus on their latest major applications in astronomy and remote sensing. Additionally, we present a mathematical model of the generalized reconstructive spectrometer and provide a summary of its principles pertaining to spectral mapping, reconstruction, and imaging. Despite its limited aperture and étendue, the reconstructive spectrometer holds great potential for future use in astronomy and remote sensing due to its compact size and exceptional ultrahigh spectral resolution.
Intrinsic photomixing detector based on amorphous silicon for envelope mixing of optical signals
Authors: Müller Maurice , Bablich Andreas , Bornemann Rainer , Marrenbach Nils , Kienitz Paul , Haring Bolívar Peter
Published: August 2023

In this work, a promising device for direct optical envelope mixing, the Intrinsic Photomixing Detector (IPD) based on hydrogenated amorphous silicon, is reported. The IPD directly generates a photocurrent proportional to the nonlinear mixing of two optical modulation envelope functions. Experiments illustrate efficient mixing in the visible range at low light levels down to ϕ1 = 4.36 mW/cm2 (444 nm) and ϕ2 = 1.03 mW/cm2 (636 nm). Modulation frequencies exceeding the MHz range are demonstrated. Electro-optical simulations identify defect-induced electrical field screening within the absorber to cause the nonlinear mixing process, opening-up the opportunity to tailor devices toward application-specific requirements. The IPD functionality paves the way toward very simple but high-performance photodetectors for 3D imaging and ranging for direct optical convolutional sensors or for efficient optical logic gates. Using amorphous silicon provides a photodetector material base, which can easily be integrated on top of silicon electronics, enabling fill factors of up to 100%.
Design and simulation of gear transmission system based on metamaterial
Authors: Dou Shuihai , Liu Yuxin , Du Yanping , Wang Zhaohua , Tu Juncheng , Sun Zhaoyong
Published: August 2023

In this research, we integrate a three-dimensional micro-/nano-lattice structure metamaterial with conventional helical gears using a composite method to reduce the vibration. A comprehensive six-degree-of-freedom nonlinear dynamics model is constructed to analyze the vibration characteristics of the resulting mechanical metamaterial gear pair. The model incorporates crucial factors such as meshing damping, error excitation, bearing support stiffness, and time-varying meshing stiffness using the dynamic–static method. The results demonstrate the good damping effect of the designed mechanical metamaterial on gear pair vibrations. This research provides theoretical insights for reducing vibrations in gear transmission systems by using mechanical metamaterial.
How wavelength affects hydrodynamic performance of two accelerating mirror-symmetric undulating hydrofoils
Authors: Lin Zhonglu , Liang Dongfang , Bhalla Amneet Pal Singh , Sheikh Al-Shabab Ahmed A. , Skote Martin , Zheng Wei , Zhang Yu
Published: August 2023

Fish schools are capable of simultaneous linear acceleration. To reveal the underlying hydrodynamic mechanism, we numerically investigate how Reynolds number Re=1000–2000, Strouhal number St=0.2–0.7, and wavelength λ=0.5–2 affect the mean net thrust and net propulsive efficiency of two side-by-side hydrofoils undulating in anti-phase. In total, 550 cases are simulated using immersed boundary method. The thrust increases significantly with the wavelength and the Strouhal number, yet only slightly with the Reynolds number. We apply a symbolic regression algorithm to formulate this relationship. Furthermore, we find that mirror-symmetric schooling can achieve a net thrust more than ten times that of a single swimmer, especially at low Reynolds numbers. The highest efficiency is obtained at St=0.5 and λ=1.2, where St is consistent with that observed in the linear-accelerating natural swimmers, e.g., Crevalle jack. Six distinct flow structures are identified. The highest thrust corresponds to an asymmetric flow pattern, whereas the highest efficiency occurs when the flow is symmetric with converging vortex streets.
An in vivo and in vitro photopolar array for precision optogenetic stimulation
Authors: Ji Yanping , Li Jiawei , Zhao Boyan , Qiu Ziqi , Wang Shirui , Wang Wensi
Published: August 2023

We propose the use of micro-LED arrays as a powerful tool to achieve precise stimulation of neuronal cells in time and space. In particular, we have developed a control system for in vivo implant stimulation and in vitro neuronal stimulation of organisms, through which up to 4096 individual micro-LED light sources can be controlled. The system can be integrated into microscopes and membrane clamp electrophysiology devices for efficient optogenetic monitoring. The final experiments show that different combinations of irradiation of the photopolar array can be used to effectively stimulate neurons transfected with photosensitive proteins by varying the light power.
High harmonic generation in monolayer MoS2 controlled by resonant and near-resonant pulses on ultrashort time scales
Authors: Peterka Pavel , Slobodeniuk Artur O. , Novotný Tomáš , Suthar Pawan , Bartoš Miroslav , Trojánek František , Malý Petr , Kozák Martin
Published: August 2023

We report on experimental investigation of nonperturbative high harmonic generation (HHG) in monolayer MoS2 in the ultraviolet spectral region driven by mid-infrared light. We study how the HHG is influenced by pre-excitation of the monolayer using resonant and near-resonant pulses in a pump–probe-like scheme. The resonant light creates high density exciton population. Due to ultrafast dephasing caused by electron–electron scattering, the HHG is suppressed in the presence of pre-excited carriers. In the case of near-resonant excitation with photon energy below the exciton transition, the dynamics of the observed suppression of the HHG yield contains a fast component, which is a consequence of momentum scattering at carriers, which are excited by two-photon transition when the two pulses temporally overlap in the sample. This interpretation is supported by comparing the experimental data with theoretical calculations of the two-photon absorption spectrum of the MoS2 monolayer. This work demonstrates a possibility to control HHG in low-dimensional materials on ultrashort timescales by combining the driving strong-field pulse with a weak near-resonant light.
On the drag reduction of an inclined wing via microstructures with the immersed boundary-lattice Boltzmann flux solver
Authors: Chen Guo-Qing , Du Zengzhi , Li Hongyuan , Lv Pengyu , Duan Huiling
Published: August 2023

Flow separation control has a wide application prospect in drag reduction for industry. This paper numerically studies the effect of microstructures on flow separation and drag reduction. Simple morphological microstructures, derived from the tilted shark scales, are attached to the wing at an angle of attack. The spacing and height of microstructures are made dimensionless by using the microstructure width and half of the wing width, respectively, that is, d̃m=dm/dAB and h̃m=hm/(H/2). The angle of attack is set to 10°. It is found that microstructures can reduce the motion amplitude of shed vortices, thereby suppressing flow separation and reducing drag. Both the planar and curved microstructures have excellent drag reduction performance. The microstructure spacing d̃m and tilt angle θ should not be too large or too small; otherwise, it will weaken the drag reduction ability. Cases d̃m=1.51, θ=20°, and θ=30° exhibit excellent drag reduction performance. The microstructure has the characteristic for being small, yet it needs to reach a certain height h̃m to effectively reduce drag. The case h̃m=0.667 is the most superior choice. Based on the proposed microstructure shape and spacing, the drag reduction performance of microstructures can reach more than 28%. Meanwhile, the drag reduction performance of microstructures increases with the improvement of the attachment proportion pm, and case pm≥50% is suggested for significant drag reduction performance. Finally, we discuss the drag reduction performance of microstructures on the wing at different angles of attack and find that microstructures can achieve good drag reduction, provided that the pressure drag caused by the flow separation is a significant proportion of the total drag and the flow separation occurs within the controllable range of microstructures.
Grain refinement and coercivity enhancement of sintered Nd–Fe–B alloys by doping eutectic alloy (Nd0.75Pr0.25)70Cu30.
Authors: Nguyen Van Dao , Kim Taek-soo , Lee Yee-Un , Hong Soon-jik
Published: August 2023

A significant enhancement in the coercivity and grain refinement was revealed for the spark plasma sintered NdFeB magnets by doping eutectic alloy (Nd0.75Pr0.25)70Cu30 powders. The commercially available NdFeB powders were mixed with (Nd0.75Pr0.25)70Cu30 powders (0, 2 and 5 wt.%) and then consolidated by spark plasma sintering at 700°C under 50 MPa. Microstructure analysis shows that the addition of (Nd0.75Pr0.25)70Cu30 alloy reduces the formation of coarse grain zone and decreases the average Nd2Fe14B grain size by intergranular phase modification. The RE-rich phase containing Nd, Pr at the Nd2Fe14B grain boundary caused the magnetic isolation effect. Hence, the coercivity increased from 18.3 kOe for un-doped NdFeB to 20.3 and 21.6 kOe with doping content of 2 and 5 wt.%, respectively. This study provides an economic way to fabricate sintered NdFeB magnets with enhanced coercivity and homogeneous nanostructure.
Cold and warmth intensify pain-linked sodium channel gating effects and persistent currents
Authors: Kriegeskorte Sophia , Bott Raya , Hampl Martin , Korngreen Alon , Hausmann Ralf , Lampert Angelika
Published: August 2023

Voltage-gated sodium channels (Nav) are key players in excitable tissues with the capability to generate and propagate action potentials. Mutations in the genes encoding Navs can lead to severe inherited diseases, and some of these so-called channelopathies show temperature-sensitive phenotypes, for example, paramyotonia congenita, Brugada syndrome, febrile seizure syndromes, and inherited pain syndromes like erythromelalgia (IEM) and paroxysmal extreme pain disorder (PEPD). Nevertheless, most investigations of mutation-induced gating effects have been conducted at room temperature, and thus the role of cooling or warming in channelopathies remains poorly understood. Here, we investigated the temperature sensitivity of four Nav subtypes: Nav1.3, Nav1.5, Nav1.6, and Nav1.7, and two mutations in Nav1.7 causing IEM (Nav1.7/L823R) and PEPD (Nav1.7/I1461T) expressed in cells of the human embryonic kidney cell line using an automated patch clamp system. Our experiments at 15°C, 25°C, and 35°C revealed a shift of the voltage dependence of activation to more hyperpolarized potentials with increasing temperature for all investigated subtypes. Nav1.3 exhibited strongly slowed inactivation kinetics compared with the other subtypes that resulted in enhanced persistent current, especially at 15°C, indicating a possible role in cold-induced hyperexcitability. Impaired fast inactivation of Nav1.7/I1461T was significantly enhanced by a cooling temperature of 15°C. The subtype-specific modulation as well as the intensified mutation-induced gating changes stress the importance to consider temperature as a regulator for channel gating and its impact on cellular excitability as well as disease phenotypes.
Mechanical and spectroscopic investigation of novel f-MWCNTS/g-C3N4/TiO2 ternary nanocomposite reinforced denture base PMMA
Authors: Jhansi Ragala , Sundeep Dola , Umadevi Kovuri , Varadharaj Eswaramoorthy K , Sastry Chebbiyam Chandrasekhara , Krishna Alluru Gopala , Raj N Sleeva , Patil Sandeep
Published: August 2023

In the present work, we report the fabrication, spectroscopic, and mechanical properties of the novel f-MWCNTS/g-C3N4/TiO2 (MGT-NCs) metal-free ternary nanocomposite reinforced denture base PMMA. The functionalised-MWCNTs were introduced into the graphitic carbon nitride (g-C3N4) nanopowders (NPs). The obtained high porous f-MWCNTS/g-C3N4 NPs were mixed with 10 wt% of TiO2 NPs previously hydrothermally synthesized. These prepared powders were characterized by XRD, FE-SEM, HR-TEM, FT-IR, and Raman spectroscopy to study the crystal structure and morphology. Using a mechanical blender 2 wt% of g-C3N4, MWCNT/g-C3N4, and MGT-NCs were sintered into PMMA heat-activated denture base polymer powder and mixed with monomer to fabricate the composites through heat curing. Three different varieties of composite specimens were prepared into flexural, impact, compression, and hardness testing standards. From the comparative assessment of results, it is found that novel MGT-NCs reinforced PMMA exhibited superior mechanical properties. The surface morphology of the fractured and compressed specimens was studied using the SEM analysis and found to have dimples and increased roughness compared to the pristine PMMA and g-C3N4, MWCNT/g-C3N4. Hence, the fabricated novel metal-free MGT-NCs can be used as a reinforcement material in PMMA denture bases to achieve a concurrent enhancement in both physical and mechanical properties.
A new graph-theoretic approach for the study of the surface of a thin sheet of a viscous liquid model
Authors: Nirmala A N , Kumbinarasaiah S , Shah Nehad Ali , Alshehri Mansoor
Published: August 2023

In this study, we considered the model of the surface of a thin sheet of viscous liquid which is known as the Buckmaster equation (BME), and presented a new graph-theoretic polynomial collocation method named the Hosoya polynomial collocation method (HPCM) for the solution of nonlinear Buckmaster equation. In the literature, the majority of the developed numerical methods considered small time step sizes like 0.01s and 0.05s to obtain relatively accurate approximations for the nonlinear BME. This study focused on optimizing the time step sizes by adopting bigger time steps sizes like 1.0s,3.0s, and 5.0s, etc without adversely affecting accuracy. First, using the Gram- Schmidt process, we generated the orthonormal functions from the Hosoya polynomial of the path graph. Then developed the functional integration matrix using orthonormal Hosoya polynomials of path graphs. With this active matrix-involved method, the nonlinear BMEs are transformed into a system of nonlinear equations and solved the equations by Newton’s method through the Mathematica software for unknown coefficients. The exactness of the proposed strategy is tested with two numerical examples. The acquired results contrasted with the current analytical solutions to these problems. Also provided the convergence analysis, comparison of error norms, graphical plots of correlation of HPCM results, and the results of other numerical methods in the literature to validate the productivity and accuracy of the newly developed HPCM.
Quantum tunneling from charged accelerating BTZ black holes
Authors: Rehman Mudassar , Gillani Usman A , Ahmed Jamil
Published: August 2023

In this work we derive the analytical expression for Hawking temperature of the charged accelerating BTZ black holes by using the WKB approximation in tunneling formalism. We have investigated the Hawking radiation of Dirac and scalar particles from these black holes. Graphical representation of Hawking temperature is also made to compare the findings in presence and absence of acceleration parameter.
Effect of Rayleigh backscattering on the multiwavelength random fiber laser bandwidth
Authors: David Allen Paul , Sulaiman Abdul Hadi , Abdullah Fairuz , Ismail Aiman , Jamaludin Md Zaini , Yusoff Nelidya Md
Published: August 2023

We investigated the effect of Rayleigh backscattering on the bandwidth of a multiwavelength random fiber laser (MWRFL). This MWRFL is based on an erbium-doped fiber amplifier (EDFA) as the gain medium and a Lyot filter as the wavelength-selective device. A high number and stable lasing line is generated with the assistance of a nonlinear polarization rotation effect induced by highly nonlinear fiber (HNLF) and optimized by a polarization controller. Longer single-mode fiber (SMF) produces wider multiwavelength bandwidth as compared to shorter SMF lengths, as 10 km, 3 km, and 0.1 km obtained 6.24 nm, 5.76 nm, and 2.75 nm wavelength bandwidth, respectively. When the SMF is removed from the setup, no Rayleigh backscattering is provided in the cavity, which led to a narrower multiwavelength bandwidth of 2.69 nm. Subsequently, the alteration of EDFA power, half-wave plate (HWP) angle, and quarter-wave plate (QWP) angles affected the degradation of multiwavelength performance. The best output spectrum is achieved at an EDFA power of 18 dBm, a HWP angle of 60°, and a QWP angle of 105°. The laser stability over a period of 120 min was excellent with a peak power deviation of 1.33 dB.
A novel simulation paradigm utilising MRI-derived phosphene maps for cortical prosthetic vision
Authors: Wang Haozhe Zac , Wong Yan Tat
Published: August 2023

Objective. We developed a realistic simulation paradigm for cortical prosthetic vision and investigated whether we can improve visual performance using a novel clustering algorithm. Approach. Cortical visual prostheses have been developed to restore sight by stimulating the visual cortex. To investigate the visual experience, previous studies have used uniform phosphene maps, which may not accurately capture generated phosphene map distributions of implant recipients. The current simulation paradigm was based on the Human Connectome Project retinotopy dataset and the placement of implants on the cortices from magnetic resonance imaging scans. Five unique retinotopic maps were derived using this method. To improve performance on these retinotopic maps, we enabled head scanning and a density-based clustering algorithm was then used to relocate centroids of visual stimuli. The impact of these improvements on visual detection performance was tested. Using spatially evenly distributed maps as a control, we recruited ten subjects and evaluated their performance across five sessions on the Berkeley Rudimentary Visual Acuity test and the object recognition task. Main results. Performance on control maps is significantly better than on retinotopic maps in both tasks. Both head scanning and the clustering algorithm showed the potential of improving visual ability across multiple sessions in the object recognition task. Significance. The current paradigm is the first that simulates the experience of cortical prosthetic vision based on brain scans and implant placement, which captures the spatial distribution of phosphenes more realistically. Utilisation of evenly distributed maps may overestimate the performance that visual prosthetics can restore. This simulation paradigm could be used in clinical practice when making plans for where best to implant cortical visual prostheses.
Neuromorphic applications in medicine
Authors: Aboumerhi Khaled , Güemes Amparo , Liu Hongtao , Tenore Francesco , Etienne-Cummings Ralph
Published: August 2023

In recent years, there has been a growing demand for miniaturization, low power consumption, quick treatments, and non-invasive clinical strategies in the healthcare industry. To meet these demands, healthcare professionals are seeking new technological paradigms that can improve diagnostic accuracy while ensuring patient compliance. Neuromorphic engineering, which uses neural models in hardware and software to replicate brain-like behaviors, can help usher in a new era of medicine by delivering low power, low latency, small footprint, and high bandwidth solutions. This paper provides an overview of recent neuromorphic advancements in medicine, including medical imaging and cancer diagnosis, processing of biosignals for diagnosis, and biomedical interfaces, such as motor, cognitive, and perception prostheses. For each section, we provide examples of how brain-inspired models can successfully compete with conventional artificial intelligence algorithms, demonstrating the potential of neuromorphic engineering to meet demands and improve patient outcomes. Lastly, we discuss current struggles in fitting neuromorphic hardware with non-neuromorphic technologies and propose potential solutions for future bottlenecks in hardware compatibility.
I-V characteristics and adsorption properties of ZnO/rGO/ZnO for gas sensing detection
Authors: Ding Jijun , Bu Yuwen , Yang Mingya , Feng Jialong , Wu Rongguo , Chen Haixia
Published: August 2023

The heterostructure consisting of zinc oxide and reduced graphene oxide (ZnO/rGO/ZnO) is prepared on cotton fabric by repeated immersion and magnetron sputtering. In addition, the gas selectivity of the sample is analyzed based on I-V characteristics under different gas atmospheres (air, methanal, ethanol, acetone and toluene). Compare with that in air atmosphere, the I-V characteristic curve under toluene gas atmosphere changes significantly, and the current decreased significantly. The experimental results show that the samples exhibit high selectivity. In order to study the intrinsic physical characteristics of the heterostructure after gas adsorption, the band structures, density of states (DOS), adsorption energy (Ead) and charge density difference (CDD) are calculated based on density function theory (DFT). The existence of rGO results in a high electrical conductivity, which is consistent with the experimental results. Meanwhile, toluene has the highest Ead (-0.85 eV) and charge transfer (0.67 e). The charge transfer results prove that a large number of electrons are transferred from the surface of the heterostructure to the vicinity of toluene molecules, which leads to a change in the electrical conductivity of the heterostructure. Based on the excellent gas selectivity, the application of cotton-based ZnO/rGO/ZnO structure in gas sensing field is promoted.
Preparation and characterization of polydodecyl benzene sulfonic acid/ polyaniline
Authors: Ma Mingming , Shi Shuai , Cui Shuhui
Published: August 2023

Poly dodecyl benzene sulfonic acid/polyaniline (PDBSA/PANI) composite was prepared by twice electropolymeization. The effects of experiment conditions such as DBSA concentration, elecrode length, twice scan potential range, scan rate and scan cycles on the charge capacity of PDBSA/PANI composite were investigated. And the optimum twice electropolymerization parameters were achieved. The functuional group and surface micrograph of PDBSA/PANI composite were characterized by FT-IR spectra and field emission scanning electron microscope, respectively. The results showed that the absorption intensities of sulfonic acid group originated from PDBSA/PANI were much more stronger than those of self-adsorbed DBSA/PANI composite. Meanwhile, the surface micrograph of PDBSA/PANI was much more fibrous than that of DBSA/PANI. All the above were advantage to the storage of charge. Thus, PDBSA/PANI was better than DBSA/PANI in charge storage.
Residual flexural tensile strength properties of notched concrete beams with high-strength steel fibers
Authors: Jin A H , Yun H D
Published: August 2023

The purpose of this study is to replace the steel bars and barbed wires in reinforced concrete structures, conduct experiments using steel fiber-reinforced concrete (SFRC), and investigate its failure modes. We conduct the experiments by performing the three-point bending test specified in the EN 14651 standard. Based on an analysis of the results obtained worldwide in recent years, we use SFRC specimens fabricated in the structural laboratory of Chungnam University in South Korea and apply the results from other researchers. The residual stresses of 625 SFRC specimens are analyzed based on the high or low strengths of the fibers and categorized according to fiber content and the aspect ratio of the fibers. The contribution of each condition to the residual flexural strength is discussed based on the results of the residual flexural strength after cracking, and it is suggested that more research and calculations are needed for high-strength steel fibers.
Features of a THz pulse generated in the metallic waveguides partially filled with nonlinear crystals
Authors: Nikoghosyan A S , Tadevosyan V R , Goltsman G N , Antipov S V
Published: August 2023

The experimental and numerical study both generation and transmission terahertz pulse in a nonlinear crystal partially filling the rectangular metallic waveguide cross-section is presented. LiNbO3 and DAST crystals have been studied since they have a high-quality factor (FOM) and optical rectification in them is the most promising method for generating an extremely strong terahertz field. Experimentally and numerically has been shown that, depending on the thickness and permittivity of a nonlinear crystal, a broadband terahertz pulse can propagate with low absorption in the form of the fundamental H10 mode or a linear superposition of Hno modes.
Optimization of Bifacial Photovoltaics by Optical Systems Feasibility Study
Authors: Mueller Helmut F.O.
Published: August 2023

Bifacial PV cells allow light to reach the cell from the rear, achieving rear side efficiencies from 60% to over 95%. The predicted annual bifacial gain in irradiance (rear / front) can be 5% to 30% depending mainly on the reflectivity of the ground (albedo). It can be increased by optical systems redirecting diffuse and direct solar radiation to the rear of the solar cell without solar tracking. The optical systems can work by the physical effects of refraction or reflection. Beside reflective gratings refractive prismatic systems can be applied, e.g., as micro-structures, which originally were developed to improve daylighting of deep rooms. Applications and production related variations are described. The arrangement of the optical system and PV module can vary according to the orientation and setup of the module, which may be in open spaces or integrated into buildings. The advantage of bifacial over monofacial cells is expressed by the “bifacial gain”. This is the additional part of the total energy that a bifacial PV system produces in comparison to a monofacial system with the same orientation and size. This additional yield is given in the literature as 5% to 30%, depending on the reflectivity of the ground and the cell type. For the redirection of solar radiation by micro-structured systems on HIT bifacial solar cells a bifacial gain of 51% to 68% can be assumed. These preliminary results have to be confirmed by tests.
Design and Realization Separable Observation Sensors of Tianwen-1 Mars Probe
Authors: Di Wu , Yang Du , Yuan Gao , Feng Wang , Miao Yu
Published: August 2023

Tianwen 1 Mars exploration mission is a high-risk mission with long cycle, high communication delay, high product reliability and harsh deep space environment. Two separate observation sensors are installed on Tianwen 1 probe. During the Earth Mars transfer phase of Tianwen 1, the first separable observation sensor was separated from Tianwen 1, which monitored the state of Tianwen 1 and its surrounding space environment. On the Mars orbit, the second separable observation sensor was separated from the Tianwen 1 probe and took a color group photograph of the Tianwen 1 probe and Mars. This paper first introduces the task requirements of separable observation sensors and the design constraints of deep space environment on products. Secondly, the composition of the separable observation sensor is introduced. Thirdly, the relevant indicators of the separable observation sensor are introduced. Finally, the ground test and in orbit test of the separable observation sensor are introduced.
A differential miniaturized thickness measurement calibration system based on laser triangulation sensors
Authors: Jin Sun , Ming Feng Zhe , Jun Zhou Yi
Published: August 2023

Steel plate thickness inspection is important in high-precision steel processing and manufacturing. Traditional inspection methods use manual contact measurement, which has low inspection efficiency and large human error, so we proposed a differential non-contact thickness measurement system based on laser triangulation sensors. Firstly, we designed a differential measurement structure by placing the laser triangulation sensors on the top and bottom of the steel plate to be measured, so that the data from the top and bottom sensors can be sampled and the steel plate thickness can be calculated simultaneously. Secondly, based on the principle of error averaging effect, we proposed a multi-point measurement averaging method to take multiple points on the surface of the steel plate and calculate the average value as the thickness of the steel plate. Further, to improve the measurement system’s long-term stability, the temperature drift is corrected by the polynomial fitting method. Finally, the experiment proves that the repeatability accuracy of our proposed measurement system can reach ±0.5um and the measurement drift is better than ±0.1% of the steel plate thickness.
Multidimensional Data Analysis of Ambient Air Quality Based on Apache Kylin
Authors: Yuan Ying , Xu Lejin
Published: August 2023

While the environmental monitoring department increases the number of monitoring points and the frequency of monitoring, it will also bring about a surge in the amount of monitoring data and computational response events. However, the traditional data statistics methods based on relational databases are ineffective in the face of huge environmental monitoring data. Aiming at ambient air quality data analysis, this paper uses Hadoop, Hive, Kylin, and other tools to build a multi-dimensional analysis platform for ambient air quality big data in a distributed environment, which realizes the unified storage, calculation, and analysis of ambient air quality monitoring data. Compared with the traditional relational database statistical analysis scheme, the proposed solution significantly improves the efficiency of statistical analysis of ambient air quality data under the condition of large data. The response time is shortened by 98%, reaching the sub-second level.
General Intelligent Dataset Description Method and Application
Authors: Ma Danchen , Zhang Shaoyang , Liu Yongli
Published: August 2023

With the development of the Internet, the growth rate of big data has exceeded the ability of human beings to obtain information from data. In the near future, faced with the sea of data, seemingly logically correct algorithms may come to the opposite conclusion, which will be a “data disaster” era. Therefore, letting data “speak” and enable data intelligence is an important problem that must be solved in the field of big data research. In this paper, we propose a “data intelligence” framework based on Brooks’s Subsumption Architecture for robotics. In this framework, we define a new dataset description method and try to encapsulate the dataset described by this method into a software container. Then, we set up the corresponding operations on the dataset container. Finally, we identify an interaction model for a “dataset agent” based on academic work on agents in the field of artificial intelligence. And we designed and implemented some functions of an intelligent document manager, which proves that our design ideas and methods are feasible.
Few-shot Object Detection Based on Sample Balance Correction
Authors: Cai Wei , Wang Xin , Yang Zhiyong , Jiang Xinhao , Chen Dong
Published: August 2023

We propose a few-shot object detection algorithm based on sample balance correction, which introduces categorical sample balance correction and positioning sample balance correction on the basis of the Faster R-CNN network to improve the performance of few-shot detection, and categorical sample balance correction increases the passing probability of the new type pre-selection box by changing the selection rules of the pre-selection box. And the similarity calculation branch is added to the detection head to help improve the classification ability, and the positioning sample balance correction solves the sample balance in the training process and the balance problem of correcting difficult samples by improving the positioning loss function. Experiments on the PASCAL VOC dataset show that the proposed algorithm improves the detection effect when the sample size is small, up to 3.2 percentage points higher than the comparison algorithm, and has good robustness and generalization ability.
Combined Prediction Model of PM2.5 Concentration Based on Wavelet Transform and LSTM
Authors: Hu Xueka , Shi Jiahao , He Cailian , Fang Jiajue
Published: August 2023

To improve the prediction accuracy of PM2.5 concentration and overcome the applicability limitation of a single prediction method, a combined prediction model of PM2.5 concentration based on wavelet transform and long short-term memory (LSTM) is proposed. The potential relationship between PM2.5 and other air quality indexes is explored by using feature engineering, and strong correlation factors are selected as input vectors. Wavelet transform is used to decompose and refine the time series of related factors at multiple scales. And the LSTM is used to train the time series in different scales, and the final prediction results are generated through reconstruction. The results show that the combined model has a better prediction effect compared with the single prediction model, which improves the prediction accuracy and model generalization ability.
New Upper Bounds on The Spectral Radius for the Hadamard Product of Nonnegative Matrices
Authors: Zhong Qin
Published: August 2023

By using the eigenvalue inclusion field theorem and the commutability of the Hadamard product, new upper bound estimations of ρ (E ∘ F) are given. The new estimations can be expressed only by the elements of two nonnegative matrices, which are operable and easy to calculate. Finally, an example is given to verify that the estimation formulas in this paper are more accurate than related conclusions.
Properties on the Fan Product of M-matrices
Authors: Zhong Qin , Li Ling
Published: August 2023

In this study, the lower bound expressions of the smallest eigenvalue q(E ★ F) are derived using the row sums of two M-matrices and the maximum of the main diagonal elements. The obtained lower bounds improve the existing related conclusions. Furthermore, the results of this paper are compared with those of related results by two specific examples to verify the accuracy of the results.
The Uncertainty Principle with Fourier Transform Derivatives
Authors: Qu Feifei
Published: August 2023

The classical uncertainty principle works for smooth signal functions. In our work, we apply the Fourier transform derivatives for the study of uncertainty principle, so that the smoothness condition for the signal functions is not required. At first, the amplitude and phase derivatives of vector-valued signal functions based on the Fourier transform are defined. Then we obtain a strong form of the uncertainty principle.
Calibrating global hydrological models with GRACE TWS: does river storage matter?
Authors: Trautmann Tina , Koirala Sujan , Guentner Andreas , Kim Hyungjun , Jung Martin
Published: August 2023

Although river water storage contributes to Total Terrestrial Water Storage (TWS) variations obtained from GRACE satellite gravimetry, it is unclear if computationally expensive river routing schemes are required when GRACE data is used for calibration and validation in global hydrological modeling studies. Here, we investigate the role of river water storage on calibration and validation of a parsimonious global hydrological model. In a multi-criteria calibration approach, the model is constrained against either GRACE TWS or TWS from which river water storage is removed. While we find that removing river water storage changes the TWS constraint regionally and globally, there are no significant implications for model calibration and the resulting simulations. However, adding modeled river water storage a-posteriori to calibrated TWS simulations improves model validation against seasonal GRACE TWS variations globally and regionally, especially in tropics and Northern low- and wetlands. While our findings justify the exclusion of explicit river routing for global model calibration, we find that the inclusion of river water storage is relevant for model evaluation.
A glitch free variability resistant high speed and low power sense amplifier based flip flop for digital sequential circuits
Authors: Shah Owais Ahmad , Nijhawan Geeta , Khan Imran Ahmed
Published: August 2023

In this work, a sense amplifier based flip flop (SAFF) is presented appropriate for high speed, high data activity and low power operations. The delay and power of the proposed flip flop have been considerably reduced as it uses a novel single-ended latch structure. The flip flop (FF) also achieves glitch free operation and can be operated and is functional at near-threshold voltage levels. SPICE simulations were carried out to do a comprehensive and quantifiable analysis between the presented architecture and formerly known architectures in 32 nm CMOS technology. The proposed design achieved a reduction of minimum 22.67% in power at nominal voltage. In terms of Power Delay Product (PDP), a reduction of 63.51% was observed. At 100 MHz clock frequency, the power dissipation was lowered by 30%. The proposed design at data activity of 100% consumes 28.24% less power whereas at activities of less than 12.5% it does not show significant improvements. However, the proposed design has an advantage in terms of speed and is 40% to 82% faster at nominal conditions and can also operate at wide supply voltage. It also has the second lowest transistor count and second lowest area. The power performance is verified by implementing the proposed design as a 4-bit shift register.
Multi-objective optimization of inconel 718 turning parameters using PCA-MARCOS and MARCOS-Taguchi
Authors: Yallese Mohamed Athmane , Boucherit Septi , Kouahla Ilyas , Belhadi Salim
Published: August 2023

In recent years, multiple-attribute decision-making (MADM) methods have gathered significant interest from researchers across various scientific fields. In the case of mechanical part machining when faced with conflicting objectives, these methods have become essential in the selection of necessary cutting parameters. The integration of these techniques with multi-objective optimization procedures has proven effective in leading to an efficient solution to a multi-attribute decision-making problem. The present study falls within this context. Its primary objective being the determination of the optimal cutting parameters that reduces tool vibration, minimizes surface roughness along withmaximizing material removal rate during the turning of Inconel 718 using a coated carbide cutting tool grade (GC1105). These various objectives have been achieved through combining the principal component analysis (PCA) method to the measurement of alternatives and ranking according to the compromise solution (MARCOS), and MARCOS method coupled with the Taguchi SN ratio. The results obtained demonstrated that both methods generated the same combination of optimal cutting parameters that achieve the aforementioned objectives and represented by a nose radius r = 0.8 mm, a cutting speed Vc = 70 mm min−1, a feed rate f = 0.08 mm rev−1, and a depth of cut ap = 0.3 mm.
Deposition and process parameter optimization of electroless Ni-B coating from a stabilizer free bath to achieve enhanced microhardness, scratch-hardness and adhesion using taguchi’s methodology
Authors: Karn Anand Kumar , Agrawal Rohit , Kumar Abhinandan , Mukhopadhyay Arkadeb
Published: August 2023

Electroless nickel boron coatings have wide industrial usage. However, they are generally obtained from a lead-stabilized bath. The present work investigates and optimizes the scratch-hardness and microhardness obtained from stabilizer-free electroless nickel boron bath in a quest to eliminate lead nitrate/heavy metals, which are potentially toxic. The bath temperature, heat treatment temperature, and duration were varied at three levels. Enhanced scratch-hardness (12.581 GPa) was obtained at 85 °C bath temperature and heat treatment at 350 °C for 1 h. At the same time, the highest microhardness (886.17 HV100) was obtained at a parametric combination of 95 °C bath temperature and heat treatment at 450 °C for 1 h. Multi-objective optimization was carried out using grey relational analysis. The parametric combination predicted in multi-objective optimization was 85 °C bath temperature and heat treatment at 350 °C for 1 h where the microhardness was 846.34 HV100. Furthermore, an analysis of variance was also carried out to investigate the importance of the factors in controlling scratch-hardness and microhardness. The highest contribution was observed from heat treatment duration. Further investigation of the optimized coating was done by the progressive scratch test, which recorded that the first critical load of failure improved compared to non-heat treated electroless Ni-B coatings. The coatings were also characterized using field emission scanning electron microscope, energy dispersive x-ray spectroscopy, and x-ray diffraction. The coatings in optimized condition showed no transverse or chevron cracks within 5–24 N.
Scaled homology and topological entropy
Authors: Hou Bingzhe , Igusa Kiyoshi , Liu Zihao
Published: August 2023

In this paper, we build up a scaled homology theory,

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-homology, for metric spaces such that every metric space can be visually regarded as “locally contractible” with this newly-built homology. We check that

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-homology satisfies all Eilenberg-Steenrod axioms except the exactness axiom whereas its corresponding

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-cohomology satisfies exactness axiom for cohomology. This homology can relax the smooth manifold restrictions on the compact metric space such that the entropy conjecture will hold for the first

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-homology group.