Dimensional Array Research Articles

Three dimensional titanium dioxide nanotube arrays induced nanoporous structures and stable solid electrolyte interphase layer for excellent sodium storage in ether-based electrolyte

The commercial feasibility of sodium ion batteries (SIBs) is currently limited by the lack of anode materials that simultaneously provide high-rate capability and long cycle stability. In this study, we report three-dimensional (3D) anatase TiO2 nanotube arrays (TiO2 NTAs) as an SIB anode for excellent sodium storage when paired with ether-based electrolyte. The TiO2 NTAs anode exhibits minimal capacity decay over 3000 cycles at 1C and 5000 cycles at 20C in ether-based electrolyte, demonstrating both excellent rate capability and long-term cycle stability. Structural analysis reveals novel discovery that the 3D TiO2 NTAs develop into unique nanoporous structures that sustain during repeated redox cycles in ether-based electrolyte. On the one hand, these nanoporous structures can provide more accessible areas for Na+ intercalation and de-intercalation, enabling fast Na+ intercalation. On the other hand, they also promote the formation of a thin and stable solid electrolyte interphase (SEI) in ether-based electrolyte that facilitates long-term cycle stability. Our investigation advances the performance of TiO2 as a promising SIBs anode material and also offers valuable insights into the impact of unique nanoporous structure to the excellent electrochemical performance.

Формирование максимума напряженности электрического поля в заданной точке пространства сфокусированной линейной антенной решеткой

The possibility of forming a maximum of the electric field strength at a given point in space with the help of a focused one-dimensional linear antenna array is considered. It is shown that the location of the maximum electric field strength does not coincide with the point of in-phase addition of electromagnetic waves emitted by the elements of the antenna array - the focusing point. The dependence of the shift of the maximum electric field strength on the focus point for various focal lengths and sizes of antenna arrays is presented. It has been found that the value of the shift in the focusing coordinates is determined only by the size of the antenna array and does not depend on the number of its elements. The relationship between a decrease in the intensity of an electromagnetic wave and a shift in the maximum amplitude of the electric field strength is described. The paper presents the dependences of the amplitude of the electric field strength for antenna arrays of various linear sizes and the calculation results confirmed the theoretical concepts. A phase portrait for antenna arrays of various sizes is presented showing the in-phase arrival of waves at a given point in space. According to the family of dependencies presented in the paper, it can be concluded that the greater the ratio of the linear dimensions of the antenna array to the focal length, the smaller the shift in the maximum amplitude of the electric field strength.re frequency plane as a result of an iterative process, which makes it possible to determine the values of the required function.

Time series analysis of daily reported number of new positive cases of COVID-19 in Japan from January 2020 to February 2023.

This study investigated temporal variations of the COVID-19 pandemic in Japan using a time series analysis incorporating maximum entropy method (MEM) spectral analysis, which produces power spectral densities (PSDs). This method was applied to daily data of COVID-19 cases in Japan from January 2020 to February 2023. The analyses confirmed that the PSDs for data in both the pre- and post-Tokyo Olympics periods show exponential characteristics, which are universally observed in PSDs for time series generated from nonlinear dynamical systems, including the so-called susceptible/exposed/infectious/recovered (SEIR) model, well-established as a mathematical model of temporal variations of infectious disease outbreaks. The magnitude of the gradient of exponential PSD for the pre-Olympics period was smaller than that of the post-Olympics period, because of the relatively high complex variations of the data in the pre-Olympics period caused by a deterministic, nonlinear dynamical system and/or undeterministic noise. A 3-dimensional spectral array obtained by segment time series analysis indicates that temporal changes in the periodic structures of the COVID-19 data are already observable before the commencement of the Tokyo Olympics and immediately after the introduction of mass and workplace vaccination programs. Additionally, the possibility of applying theoretical studies for measles control programs to COVID-19 is discussed.

On the halves of double and 3-dimensional Riordan arrays

The vertical half, horizontal half and skew half of a Riordan array D=(dn,k)n,k∈N have been deeply studied by Yang, He, Barry and others. In this paper, we concentrate on using compression to study various halves of generalized Riordan arrays, such as double Riordan arrays, j-th order Riordan arrays. As applications, in the various halves of 3-dimensional Riordan array cases, we derive some identities related to the classical sequences such as Fibonacci, Pell, Pell-Lucas, Jacobsthal-Lucas and Jacobsthal numbers.

Optimized planar printed UCA configurations for OAM waves and the associated OAM mode content at the receiver

SummaryUtilization of planar printed uniform circular antenna arrays (UCA) to generate the orbital angular momentum (OAM) carrying waves in the millimeter‐wave (mmWave) frequency band is advantageous from the viewpoints of easy signal modulation and mode reconfiguration, low cost, low profile, and straightforward integration with the existing broadband wireless infrastructure. The OAM mmWave UCA are highly promising as the enablers of very high transmission data rates required by hybrid 5G/6G optical and wireless communication systems by complementing and enhancing other technologies currently in use. Therefore, we here contribute a detailed electromagnetic analysis of important constraints of such antenna arrangements aimed at short‐range multimode OAM wave transmission. We investigate (i) the required antenna array dimensions and optimized UCA arrangements for a particular link range and (ii) the corresponding mode structure of OAM waves in the plane of receiving arrays. Four relatively simple antenna configurations operating in the 60‐GHz band are compared. Theoretical assumptions based on ideal OAM modes are critically assessed and, using state‐of‐the‐art numerical electromagnetic analysis, compared to realistically generated OAM waves. The proposed “cyclic transmission setup” resulted in much lower unwanted field components in the region of receiving arrays. RMS magnitudes of unwanted modes are on average about 64% of the received mode, in comparison with 80% (up to 94%) for sequential transmission. The observed mode impurities and mode mixing effects at the receiver indicate the need to dedicate more attention to the system‐level design, the development of efficient receiving arrays, the MIMO processing, and the stream separation.

Modified bow-tie antenna array with efficient electric near-field enhancement for terahertz band

Antenna arrays can induce strong electric near-field enhancement to improve the performance of biological imaging resolution, macromolecule detection sensitivity, and sensing accuracy. However, the use of antenna arrays to regulate both the electric near-field enhancement factor and area has rarely been reported. In this paper, a novel modified bow-tie (MBT) antenna array is proposed for better near-field enhancement performance in terahertz (THz) regime. Using commercially available high frequency structure simulator (HFSS), the dimensions of the MBT antenna array, including gap width, arm length, array period, and substrate thickness, are optimized to improve electric near-field enhancement performance in terms of higher factor, larger area, more controllable peak frequency, and wider 1-dB bandwidth. The as-optimized MBT and bow-tie (BT) THz antenna arrays are fabricated on quartz substrate via lithography and lift-off process. The normalized transmittances of the MBT and BT antenna arrays are characterized by THz time-domain spectroscopy (THz-TDS) and compared with the corresponding simulated near-field enhancement factor and normalized transmittance. The results indicate that the MBT antenna array outperforms the BT antenna array with a three-fold increase in near-field enhancement area and a 66.7% wider 1-dB bandwidth, and therefore can be used to enhance detection sensitivity and sensing accuracy in weak terahertz environment.

Facile growth of perovskite nanoparticles confined on dimension-controlled Si nanorod arrays for various promising photophysical applications

In this study, a facile growth of hybrid perovskite nanoparticles (NPs) has been demonstrated on mesoporous, high-aspect ratio, morphology-controlled Si nanorod (NR) arrays. A generic method of directly confining perovskite nanocrystallites (average size <7 nm) on a mesoporous substrate without the use of colloidal stabilization was introduced. The perovskite NPs coated on dimension-and position-controlled Si NR arrays were systematically investigated by their various photophysical properties such as optical reflectance, cathodoluminescence (CL), and photoluminescence (PL) behaviors at both room temperature and low temperature. The dimension and position of the Si NR arrays were controlled by e-beam lithography followed by selective metal-assisted chemical etching (MACE). Organic-inorganic perovskite NPs were synthesized on the surface of Si NR array by spin coating of perovskite precursor solution and followed by annealing. The porous and rough sites on the surface of the NR arrays acted as nucleation centers for the formation of perovskite NPs. Due to the excitonic recombination of CH3NH3PbBr3, the NPs confined on the various NR templates exhibited strong PL emission in the 505–510 nm region. Furthermore, due to greater radiative recombination and lesser carrier trapping in the NPs, the PL and CL emission intensities of the perovskite NPs localized on the surface of the NR array were dramatically increased (PL enhancement factor ∼ 7.7, when NR aspect ratio ∼ 17.2) as compared to the bulk perovskite microcrystals. The low-temperature PL study revealed higher exciton binding energy of the NPs as compared to the bulk microcrystalline film. A systematic investigation revealed that the optical absorption, as well as the emission color of the perovskite NPs, can be tuned by the aspect ratio of the Si NR arrays. The results of our studies indicate the application of bandgap engineering of perovskite nanocrystals through confinement in a mesoporous, well-organized, regularly-ordered template as a powerful tool for tuning the emission wavelength in next-generation photonic sources. Furthermore, the important findings on the periodic array of photoactive nanoscale materials introduced in this manuscript may open up huge opportunities in numerous cutting-edge applications such as light emitting diode arrays, photodetector arrays, individually addressable devices, display devices with controlled pixel size and pixel density, etc.

EpilepsyNet: Novel automated detection of epilepsy using transformer model with EEG signals from 121 patient population

BackgroundEpilepsy is one of the most common neurological conditions globally, and the fourth most common in the United States. Recurrent non-provoked seizures characterize it and have huge impacts on the quality of life and financial impacts for affected individuals. A rapid and accurate diagnosis is essential in order to instigate and monitor optimal treatments. There is also a compelling need for the accurate interpretation of epilepsy due to the current scarcity in neurologist diagnosticians and a global inequity in access and outcomes. Furthermore, the existing clinical and traditional machine learning diagnostic methods exhibit limitations, warranting the need to create an automated system using deep learning model for epilepsy detection and monitoring using a huge database. MethodThe EEG signals from 35 channels were used to train the deep learning-based transformer model named (EpilepsyNet). For each training iteration, 1-min-long data were randomly sampled from each participant. Thereafter, each 5-s epoch was mapped to a matrix using the Pearson Correlation Coefficient (PCC), such that the bottom part of the triangle was discarded and only the upper triangle of the matrix was vectorized as input data. PCC is a reliable method used to measure the statistical relationship between two variables. Based on the 5 s of data, single embedding was performed thereafter to generate a 1-dimensional array of signals. In the final stage, a positional encoding with learnable parameters was added to each correlation coefficient's embedding before being fed to the developed EpilepsyNet as input data to epilepsy EEG signals. The ten-fold cross-validation technique was used to generate the model. ResultsOur transformer-based model (EpilepsyNet) yielded high classification accuracy, sensitivity, specificity and positive predictive values of 85%, 82%, 87%, and 82%, respectively. ConclusionThe proposed method is both accurate and robust since ten-fold cross-validation was employed to evaluate the performance of the model. Compared to the deep models used in existing studies for epilepsy diagnosis, our proposed method is simple and less computationally intensive. This is the earliest study to have uniquely employed the positional encoding with learnable parameters to each correlation coefficient's embedding together with the deep transformer model, using a huge database of 121 participants for epilepsy detection. With the training and validation of the model using a larger dataset, the same study approach can be extended for the detection of other neurological conditions, with a transformative impact on neurological diagnostics worldwide.

The halves of a 3-dimensional Riordan array

For a Rirodan array, its vertical half and horizontal half are studied separately before. In this paper, we propose the (m1,s1,r,m2,s2,l)-halves of a 3-dimensional Riordan array, which are natural generalizations of the skew halves of a usual Riordan array in [21]. Let G=[gi,j,k]i,j,k≥0 be a 3-dimensional Riordan array, its (m1,s1,r,m2,s2,l)-halves H=[hi,j,k]i,j,k≥0 are defined byhi,j,k=g(m1+1)i+(s1−2)j+r,m1i+(s1−1)j+r,m2i+(s2−1)j+lk. We obtain that the (m1,s1,r,m2,s2,l)-halves of a 3-dimensional Riordan array are all 3-dimensional Riordan arrays. We also consider the (m1,s1,r,m2,s2,l)-antecedents of a 3-dimensional Riordan array.

Twisted sinc-correlation Schell-model array beams.

We introduce a class of twisted sinc-correlation partially coherent array sources, by applying the construction theory of correlation function. Spectral density of such novel focused beam propagating in free space is analyzed. It is shown that the intensity distribution presents a good twisted effect and splitting phenomenon upon propagation. The array dimension, the intensity distribution and spatial distribution of the lobes can be flexibly regulated by altering the source parameters. We also explore the spatial evolution of multiple correlation singularities of this light field, where the phase distribution appears as a rotational spiral windmill profile during propagation. Furthermore, the coherence orbital angular momentum of the twisted source beam is investigated. These findings could be useful in the particle manipulation and free-space optical communication.

Oxygen plasma induced solvent resistance of polystyrene particles enables the fabrication of ultra-thin free-standing crosslinked polymer films

Plasma-treated polystyrene particles (PSP) are key building blocks in the fabrication of two- dimensional nanostructure arrays. Oxygen plasma etching can shrink PS particles and is a widespread tool in fundamental research and applications, but its effect has not been well understood. Here, we show that oxygen plasma induces an ultra-thin cross-linking layer on the surface of the PSPs, which increases their solvent resistance. We found in X-ray photoelectron spectroscopy (XPS) fine structure and valence band probing that the polymer CC bonds are breaking and recombining to form oxygenated functional groups. Our results explain, why oxygen plasma etched PS particles are more difficult to dissolve in nanofabrication procedures. Further, we used the ultra-thin cross-linked polymer layer to construct novel substrate-base microcavity arrays.

Compact Sub 6 GHz Dual Band Twelve-Element MIMO Antenna for 5G Metal-Rimmed Smartphone Applications.

In this paper, a twelve-antenna system is designed for 5G smartphones with metal frames. The system is compact and operates on dual bands within the sub-6 GHz frequency range using multiple-input multiple-output (MIMO) technology. Two sets of six-antenna units are included in the system, arranged in a diagonal mirror-image configuration, and positioned at the center of the circuit board's longer edges. The profile height of each of the six-antenna units is only 3 mm, and the overall array dimensions are 105 × 3 × 3.1 mm3. A single antenna unit is 15 × 3 × 3.1 mm3 (0.173 λ × 0.035 λ × 0.036 λ, where λ equals the free-space wavelength of 3450 MHz). The arrangement of the antennas in the six-antenna units is parallel, with a 3 mm separation between adjacent antennas. The antenna structure comprises of an inverted L-shaped feed branch and two inverted L-shaped short-circuit branches integrated into part of the metal frame. The proposed array can form multiple resonance paths, achieving dual-band operation at 3300-3600 MHz and 4800-5000 MHz. The measured isolation of this twelve-antenna system within the operating frequency band is over 10 dB, and the measured antenna efficiency is greater than 36%. Therefore, the system is suitable for use in smartphones with high screen-to-body ratios and metal frames.

Non-invasive preoperative prediction of Edmondson-Steiner grade of hepatocellular carcinoma based on contrast-enhanced ultrasound using ensemble learning.

This study aimed to explore the clinical value of non-invasive preoperative Edmondson-Steiner grade of hepatocellular carcinoma (HCC) using contrast-enhanced ultrasound (CEUS). 212 cases of HCCs were retrospectively included, including 83 cases of high-grade HCCs and 129 cases of low-grade HCCs. Three representative CEUS images were selected from the arterial phase, portal vein phase, and delayed phase and stored in a 3-dimensional array. ITK-SNAP was used to segment the tumor lesions manually. The Radiomics method was conducted to extract high-dimensional features on these contrast-enhanced ultrasound images. Then the independent sample T-test and the Least Absolute Shrinkage and Selection Operator (LASSO) were employed to reduce the feature dimensions. The optimized features were modeled by a classifier based on ensemble learning, and the Edmondson Steiner grading was predicted in an independent testing set using this model. A total of 1338 features were extracted from the 3D images. After the dimension reduction, 10 features were finally selected to establish the model. In the independent testing set, the integrated model performed best, with an AUC of 0.931. This study proposed an Edmondson-Steiner grading method for HCC with CEUS. The method has good classification performance on independent testing sets, which can provide quantitative analysis support for clinical decision-making.

Characterization of compressible flow through microscale orifice arrays

Compressible flow through arrays of circular micro-orifices was experimentally and numerically studied to better understand how the characteristic dimensions of micro-orifices used in macroscale fluidic systems using a plurality of micro-orifices impacts discharge coefficient. The studies were carried out with micro-orifice diameters ranging from 125 μm to 1000 μm, with the number of micro-orifices in an array ranging from 2 to 64, and at gauge inlet pressures ranging from 25 to 600 kPa venting to atmospheric pressure. Results showed that micro-orifice diameter to thickness aspect ratio and wall profile were significant factors in determining discharge coefficient. The number of micro-orifices in a system was found to have negligible impact on discharge coefficient so long as the micro-orifices were separated by two diameters or more. When this spacing was maintained, two dimensional axisymmetric micro-orifice numerical studies produced discharge coefficients that agreed well with experimental data gathered on three dimensional micro-orifice arrays. The micro-orifice arrays produced discharge coefficients as high as 0.997 using photochemically etched micro-orifices, 0.981 using silicon etched micro-orifices, and 0.831 with drilled micro-orifices.

Concentration estimates for functions of finite high‐dimensional random arrays

AbstractLet be a ‐dimensional random array on whose entries take values in a finite set , that is, is an ‐valued stochastic process indexed by the set of all ‐element subsets of . We give easily checked conditions on that ensure, for instance, that for every function that satisfies and for some , the random variable becomes concentrated after conditioning it on a large subarray of . These conditions cover several classes of random arrays with not necessarily independent entries. Applications are given in combinatorics, and examples are also presented that show the optimality of various aspects of the results.

Handling mode and polarization in fiber by fs-laser inscribed (de)multiplexer and silicon switch array

The emergence of dynamic optical switching has opened up new perspectives for lightening the ever growing load on the electrical switches and routers, to meet the increasing demand on high-speed and flexible data processing and management in fiber-optic communications. Despite diversity schemes of optical switching in the single-mode regime, multi-mode switching of the hybrid fiber and chip system enabled by photonic integrated circuits, especially for the fiber-chip-fiber system, is still an outstanding challenge. Here, we propose and demonstrate the mode and polarization transmission and switching fiber-chip-fiber system with few-mode fibers (FMFs), including the FMF links for mode- and polarization-division multiplexing data transmission, the femtosecond (fs)-laser inscribed 3-dimensional (3D) photonic lantern silica chip for (de)multiplexing and coupling between FMFs and chip, and the topology-optimized N × N non-blocking 2-dimensional (2D) silicon switch array chip for switching and routing. Using 30-Gbaud quadrature phase-shift keying signals on wavelength-division multiplexing (WDM) channels, the WDM-compatible hybrid mode/polarization transmission, switching and routing system with FMFs, fs-laser inscribed silica (de)multiplexing chip and silicon switch array chip are demonstrated in the experiment with favorable operation performance. The demonstration may open the door for developing robust multi-dimensional optical data processing in fiber-optic communication systems with versatile fibers and chips.

A layout-dependent formula for the critical separation size of parallelogram-type deterministic lateral displacement arrays

The accurate and general formulation of the critical separation size is crucial for the effective design and application of passive microfluidic devices. However, the current formulas for the deterministic lateral displacement (DLD) technique are inadequate in accounting for its structural complexity. To address this limitation, we conducted mesoscopic hydrodynamics simulations to assess the separation performance of various parallelogram-type circular post arrays. Based on the simulation results, we developed a new layout-dependent formula that takes into account key geometric parameters, such as the lateral gap size, row shift fraction, and aspect ratio of downstream and lateral post-post distances, to characterize the lateral gap dimension, periodicity, and asymmetry of DLD arrays, respectively. This formula demonstrated high accuracy over a wide design space, precisely predicting the critical separation sizes of many asymmetric DLD devices in experiments. Furthermore, it is worth noting that when the downstream gap size expands, the veering flow strengthens, which, in turn, results in an increase in the critical separation size. These findings shed light on the unique separation mechanism induced by array asymmetry and present a powerful design tool for maximizing the potential of asymmetric DLD devices.

New Packaging Technology for 2-dimensional VCSEL Arrays and Their Electro-Optical Performance and Applications

At IMAPS2021, we reported on 1-dimensional VCSEL arrays and the packaging technology developed for these arrays, but this time we present the manufacturing workflow and look at the challenges presented by the packaging of special long-wavelength 2-dimensional vertical-cavity surface-emitting laser (VCSEL) arrays in various dimensions. We will show that available packaging technologies for epoxy application by silk screening, die- and wire bonding can be adapted for the unique properties of the 2D VCSEL arrays, delivering high accuracy for production with great overall yield. Proof of the excellent reliability and lifetime will be given through mechanical and electro-optical testing results. The technologies developed for 2D laser arrays will enable new devices for various new applications like high channel count interconnects for data communication and high power VCSEL solutions for 3D sensing. The perfected wire bonding process secured a homogeneous monometallic structure of the wire bonds, a reduced, well defined bond loop height, with sufficient clearance of the bonding wire above the VCSEL surface. Properly set-up manufacturing procedures for the packaging of the VCSEL arrays are necessary to achieve high performance and reliability of the products presented. Processing of large 2D-VCSEL arrays will be part of the paper. 2D arrays have enabled VCSEL technologies to address a wide range of new laser-based sensing applications. VCSEL products vary from laser chips with only a few emitters for proximity sensors up to several thousands of emitters for LiDAR systems. Applications include systems for the automotive, industrial, medical and consumer markets. There is a strong and growing market opportunity for long wavelengths VCSELs, e.g. based on InP material enabling single mode and multi-mode 2D-VCSEL arrays from 1.3 to beyond 2 µm. For 3D sensing systems and free-space optical communication, long wavelength 2D-VCSEL arrays offer improved eye safety and further benefits. The long wavelength VCSELs discussed in this paper can be deployed in a wide range of sensing and optical communication applications.

Design and Performance of Amorphous Silicon Based on Uncooled Bolometer-Type Infrared Focal Plane Arrays

Uncooled bolometric type thermal detectors , combined into a matrix and placed into a focal plane array have the following characteristics : low cost , operation at room temperature , compatibility with the silicon CMOS technology , and high detecting performance ; therefore recently it became a hot spot in infrared or terahertz detection field . The performance of uncooled infrared focal plane detector arrays depends on the optimization of critical parameters which are determined by geometrical design and the electrical , optical , and thermal physical properties of the detector materials . We report the study of a fabrication process and characterization of two (2D) dimensional arrays of uncooled microbolometers based on silicon (α- Si ) thermo-sensing films . Because these arrays substantially reduce sensor size , they are becoming the preferred format for most modern applications .

Cu2O quantum dots modified α-Ga2O3 nanorod arrays as a heterojunction for improved sensitivity of self-powered photoelectrochemical detectors

Long distance charge transfer will lead to the recombination of carriers, which seriously limits the practical application of photoelectrochemical (PEC) detector. In this work, a self-powered solar-blind photodetector based on a mixed dimensional α-Ga2O3 nanorod arrays and Cu2O quantum dots has been prepared by a simple hydrothermal method and a two-part impregnation method. Cu2O quantum dots can form type Ⅱ heterojunction with α-Ga2O3 and effectively reduce the photoinduced electron and hole recombination due to their short carrier transport distances. Just because of this, α-Ga2O3 photodetectors modified by Cu2O quantum dots present special self-power optical response at 254 nm, with optical flow densities of 13.88 μA/cm2, large responsivity of 4.57 mA/W, high detection sensitivity of 2.107 × 109 Jones and fast photoresponse time of 0.815 s/0.978 s. This kind of thought provides a simple and feasible method for the preparation of α-Ga2O3 and other semiconductor oxides based on PEC photodetectors.