Line Spacing Research Articles

Laser-assisted screen-printing of graphene folded reflectarray antenna for millimeter-wave applications

Antennas operating at high frequency bands are sought after for applications in 5G, satellite, radar, and other communication systems. Graphene, a two-dimensional material known for its exceptional conductivity, mechanical strength, and chemical stability, is anticipated to serve as a viable substitute for copper in antenna applications. However, researches on graphene antennas at millimeter-wave and higher frequencies are mainly limited to theory and simulation, due to the fabrication challenges of achieving high-precision graphene patterns. Herein, we present the design and fabrication of a graphene folded reflectarray antenna (FRA) operating at millimeter-wave. The FRA is fabricated using screen-printing of graphene ink on an RT5880 substrate, followed by laser engraving for precise patterning. The main reflector has 918 patch units, and the polarizing grids have line widths and spacings of 100 μm. Measurements demonstrate that the antenna has a realized peak gain of 21.37 dBi at 37.5 GHz. The radiation patterns show a 3 dB beamwidth of 6° and 4° in the E-plane and H-plane respectively, with cross-polarization more than −18 dB. The laser-assisted screen-printing method provides a feasible strategy for the precision manufacture of graphene communication devices.

Electrowriting patterns and electric field harness directional cell migration for skin wound healing

Directional cell migration is a crucial step in wound healing, influenced by electrical and topographic stimulations. However, the underlying mechanism and the combined effects of these two factors on cell migration remain unclear. This study explores cell migration under various combinations of guided straight line (SL) spacing, conductivity, and the relative direction of electric field (EF) and SL. Electrowriting is employed to fabricate conductive (multiwalled carbon nanotube/polycaprolactone (PCL)) and nonconductive (PCL) SL, with narrow (50 μm) and wide (400 μm) spacing that controls the topographic stimulation strength. Results show that various combinations of electrical and topographic stimulation yield significantly distinct effects on cell migration direction and speed; cells migrate fastest with the most directivity in the case of conductive, narrow-spacing SL parallel to EF. A physical model based on intercellular interactions is developed to capture the underlying mechanism of cell migration under SL and EF stimulations, in agreement with experimental observations. In vivo skin wound healing assay further confirmed that the combination of EF (1 V cm−1) and parallelly aligned conductive fibers accelerated the wound healing process. This study presents a promising approach to direct cell migration and enhance wound healing by optimizing synergistic electrical and topographic stimulations.

Influence of Oxide Formation Following Ultrashort Pulsed Laser Micromachining on Self‐Propagating Reactions in Free‐Standing Ni/Al Reactive Multilayer Foils

Reactive metallic multilayers, renowned for their exothermic self‐propagating reactions, show a distinct ability to achieve minimal thermal influence in processes such as welding and soldering, where minimizing the thermal impact on the material being joined is crucial. Ultrashort pulsed lasers offer precision micromachining with negligible thermal damage, making them ideal for processing such sensitive materials. However, the formation and redeposition of oxide phases is a commonly observed side effect, especially when structuring in ambient air. This study investigates the effects of oxide formed after femtosecond laser treatment on self‐propagating properties, including propagation velocity and microstructure of Ni/Al reactive multilayer foils. Samples with varied line spacings between laser‐cut trenches are created. Scanning electron microscopy, high‐speed camera videography, and image analysis are employed to analyze the microstructure and quantify velocities. Thermal simulations enhance the understanding of the oxide's role in self‐propagating dynamics. The findings suggest that even a small oxide layer significantly decelerates the self‐propagating reaction. The oxide functions as a thermal ballast by absorbing the thermal energy generated during the reaction, without actively participating in the reaction mechanism.

The effect of nonlocal disk processes on the volatile CHNOS budgets of planetesimal-forming material

Context. The bulk abundances of CHNOS-bearing species of a planet have a profound effect on its interior structure and evolution. Therefore, it is key to investigate the behavior of the local abundances of these elements in the solid phase in the earliest stages of planet formation, where micrometer-sized dust grows into larger and larger aggregates. However, the physical and chemical processes occurring in planet-forming disks that shape these abundances are highly coupled and nonlocal.Aims. We aim to quantify the effects of the interplay between dynamical processes (turbulent diffusion, dust settling and radial drift), collision processes (coagulation and fragmentation), and the adsorption and desorption of ices on the abundances of CHNOS in local disk solids as a function of position throughout the planet-forming region.Methods. We used SHAMPOO (Stochastic Monomer Processor), which tracks the ice budgets of CHNOS-bearing molecules of a dust monomer as it undergoes nonlocal disk processing in a Class I disk. We used a large set of individual monomer evolutionary trajectories to make inferences about the properties of the local dust populations via a stochastic analysis of 64 000 monomers on a preexisting spatial grid.Results. We find that spatially, monomers can travel larger distances farther out in the disk, leading to a larger spread in positions of origin for a dust population at, for example,r= 50 AU compared tor= 2 AU. However, chemically, the inner disk (r≲ 10 AU) is more nonlocal due to the closer spacing of ice lines in this disk region. Although to zeroth order the bulk ice mantle composition of icy dust grains remains similar compared to a fully local dust population, the ice mass associated with individual chemical species can change significantly. The largest differences with local dust populations were found near ice lines where the collisional timescale is comparable to the adsorption and desorption timescales. Here, aggregates may become significantly depleted in ice as a consequence of microscopic collisional mixing, a previously unknown effect where monomers are stored away in aggregate interiors through rapid cycles of coagulation and fragmentation.Conclusions. Nonlocal ice processing in a diffusion-dominated, massive, smooth disk has the most significant impact on the inner disk (r≲ 10 AU). Furthermore, microscopic collisional mixing can have a significant effect on the amounts of ice of individual species immediately behind their respective ice lines. This suggests that ice processing is highly coupled to collisional processing in this disk region, which implies that the interiors of dust aggregates must be considered and not just their surfaces.

THE EFFECTS OF LASER MICRO-ENGRAVING VARIABLES ON THE SURFACE CHARACTERISTICS OF THE Ti-6Al-7Nb ALLOY

This investigation aims to analyze the impact of scanning direction, scanning speed, and power level (%) on the surface roughness of Ti-6Al-7Nb alloy specimens subjected to laser micro-engraving. The laser micro-engraving process was carried out by scanning the predetermined geometric configuration six times. Factorial analysis was implemented to determine the impact of system parameters on the surface roughness. Throughout the micro-engraving operations, line spacing, frequency, and pulse width parameters were maintained at a consistent value of 0.03 mm, 100 kHz, and 300 ns, respectively. The optimal conditions for achieving the lowest surface roughness were observed at a scanning speed of 700 mm/s, a power level of 60%, and a scanning direction of 90°. Moreover, in accordance with the experimental parameters employed in this investigation, it was observed that increasing the scanning speed while maintaining a constant power level (%) reduced surface roughness. There was a direct correlation between the increase in power level (%) and a corresponding increase in surface roughness.

Optimization model for multibeam sounding line deployment based on genetic algorithm

Multibeam sounding technology is a cutting-edge method used for measuring underwater topography, widely applied across various fields. The actual seafloor terrain often exhibits significant fluctuations, leading to challenges such as insufficient coverage in shallow areas and excessive overlap in deep-water zones, resulting in inefficient operations. Rational selection of line spacing helps improve measurement efficiency and ensures data integrity. In this paper, taking the 2023 National College Student Mathematical Modeling Competition Problem B as a background, we conduct a thorough analysis of the variation patterns of the coverage width of multibeam sounding strips with respect to various parameters. We establish models for ocean depth and coverage width, determining how the strip coverage width changes with distance and the angle between survey lines in different scenarios. Finally, employing genetic algorithms and differential methods, we identify decision variables, objective functions, and constraints to formulate a nonlinear programming model. Through iterative searches, we obtain an optimal sounding line deployment plan that maximizes coverage of the target sea area while keeping the overlap rate below 20%. The calculated missed measurement error is approximately 32.774%, and the overlap rate is around 10.477%, indicating a high level of model accuracy.

Line spacing effect on the giant magnetoimpedance behavior on microribbon with meander type: a comparison of theory and experiment

Purpose Microribbon with meander type based on giant magnetoimpedance (GMI) effect has become a research hot spot due to their higher sensitivity and spatial resolution. The purpose of this paper is to further optimize the line spacing to improve the performance of meanders for sensor application. Design/methodology/approach The model of GMI effect of microribbon with meander type is established. The effect of line spacing (Ls) on GMI behavior in meanders is analyzed systematically. Findings Comparison of theory and experiment indicates that decreasing the line spacing increases the negative mutual inductance and a consequent increase in the GMI effect. The maximum value of the GMI ratio increases from 69% to 91.8% (simulation results) and 16.9% to 51.4% (experimental results) when the line spacing is reduced from 400 to 50 µm. The contribution of line spacing versus line width to the GMI ratio of microribbon with meander type was contrasted. This behavior of the GMI ratio is dominated by the overall negative contribution of the mutual inductance. Originality/value This paper explores the effect of line spacing on the GMI ratio of meander type by comparing the simulation results with the experimental results. The superior line spacing is found in the identical sensing area. The findings will contribute to the design of high-performance micropatterned ribbon with meander-type GMI sensors and the establishment of a ribbon-based magnetic-sensitive biosensing system.

Subglacial bedform and moat initiation beneath Rutford Ice Stream, West Antarctica

The accuracy of sea-level rise predictions is highly dependent on reliably understanding the subglacial environment beneath ice streams. Bedforms result from the interaction between ice and its substrate, and therefore have the potential to shed light on poorly understood basal conditions influencing ice dynamics. However, theoretical models of bedform formation are often based on observations from deglaciated areas or from sparsely-sampled geophysical surveys over glaciated regions. Here, we use high-resolution three- and two-dimensional radar and seismic data to reveal details of the initiation and evolution of a subglacial bedform beneath Rutford Ice Stream, West Antarctica. Radar surveys at 20 m and 50 m line spacing allow detailed imaging of bed topography, including a moat up to 55 m deep, surrounding the upstream end of a 50-m high and >18-km long bedform. Many models rely on either a topographical or a locally resistant seed point to initiate bedform formation. The bedform described here is mostly composed of soft sediment (porosity >0.3) and lacks a boulder or outcrop, suggesting the bedform initiated without a topographic seed point. Sediment at the upstream end of bedforms appears stiffer over a distance of 2.3 km. We suggest sediment inhomogeneities in the initially flat bed cause the deposition of sediment, which, assuming resistant enough, acts as a seed point for bedform extension and moat erosion. The moat's geometry and its truncation of other bedforms suggest that it was eroded after the deposition of surrounding bedforms. These observations from a modern ice stream deliver information of subglacial processes involved in the initiation as well as in situ high-resolution topography and properties of bedforms and moats. Using these observations numerical models can be tested and developed accordingly.

Особенности функционирования периферийных пунктуационных знаков в эпистолярных текстах малограмотных авторов

The research aims to identify the established norm of using peripheral punctuation marks in epistolary texts and to evaluate the functioning of peripheral punctuation in the letters by semiliterate authors relative to this norm. The scientific novelty of the work lies in the first-ever examination of the functions of peripheral punctuation marks in the context of the private official letters written by semiliterate authors. Additionally, the notion of a fixed function was introduced for the first time as a tool necessary for investigating whether peripheral punctuation marks are used in accordance with the norm established within a specific textual genre. The research findings showed that the use of peripheral punctuation in the letters by semiliterate authors may deviate from the generally accepted punctuation norm in the epistolary genre. It was found that norm violations primarily occur in the use of spatial-graphic signs, such as paragraph breaks, text column changes, increased line spacing and spacing between words. As a result of the study on the functioning of peripheral marks in the letters by semiliterate individuals, the following features of peripheral punctuation were also identified: the interchangeability and universalization of punctuation marks, as well as the standardization of their functions.

Micro-mechanical investigation of maraging steel during in-situ tensile test

ABSTRACT The research aimed to examine the development of slip bands in 12Cr-9Ni maraging stainless steel through in-situ tensile testing in scanning electron microscopy (SEM) and atomic force microscopy (AFM). A comprehensive approach was employed, which included assessing strain distribution and the grain boundary character distribution (GBCD) at the intermediate plastic strain steps. During plastic deformation, dislocation pile-up leads to the formation of slip bands in the material. It was discovered that slip band formation, as well as slip line spacing, exhibit crystallographic orientation dependence. Finally, fractography was employed to unveil the likely fracture mechanism and further link it to the formation of slip bands at higher strain levels.

Elucidating the effects of surface wettability on boiling heat transfer using hydrophilic and hydrophobic surfaces with laser-etched microchannels

This study explores the nuanced interplay between surface wettability and morphology in nucleate boiling heat transfer. Surfaces with identical microstructures but varying wettability are created on copper substrates using laser texturing and a hydrophobic agent. The spacing between laser-etched microchannels is adjusted to achieve different contact angles and percentages of laser-textured areas. Boiling performance is assessed with variations in channel spacing and surface coverage, revealing significant differences between hydrophilic and hydrophobic surfaces. The critical heat flux (CHF) enhancement mechanisms are identified, emphasizing either enhanced liquid replenishment or separate boiling and liquid-supply regions. A critical laser line spacing of 100 μm is determined, where hydrophobic and hydrophilic variants exhibit similar CHF. Interestingly, hydrophilic surfaces show a weak correlation between the heat transfer coefficient (HTC) and contact angle, while hydrophobic surfaces demonstrate a strong correlation. This separation of surface morphology and wettability confirms that lower wettability promotes early nucleate boiling and high HTC, whereas hydrophilic variants contribute to enhanced CHF with lower HTC. These distinctions are most prominent at high coverage with laser-textured areas and diminish as coverage decreases. The findings provide valuable insights into optimizing surface properties for efficient boiling heat transfer applications.

Simultaneously achieving excellent heat aging resistance and grip performance in carbon black/glass flake/EPDM rubber composite for overhead line spacers

The preparation of wire clamp rubber with semiconductivity, low compression set (C-Set), high mechanical strength, heat aging resistance, and high grip strength is vital for overhead line spacers. This study delves into the formulation design of high-performance ethylene-propylene-diene monomer (EPDM) composite materials for wire clamp rubber. The effects of the vulcanization system, carbon black type, and loading on the essential material properties of EPDM rubber were investigated. The results showed that a hybrid vulcanization system containing peroxide and sulfur simultaneously endowed EPDM rubber with high elasticity and tear strength. N330 carbon black-filled EPDM rubber had the advantages of semiconductivity and high tensile strength, and N774 carbon black-filled EPDM rubber exhibited low C-Set and high heat aging resistance. When EPDM rubber was reinforced with the mixture of 50 phr N330 and 20 phr N774 carbon black, the rubber synchronously exhibited semiconductivity (2.64×106 Ω·cm), high tensile strength (20.2 MPa), low C-Set (32.5%, 150°C×3d), and high heat aging resistance (maintaining 98% of its initial tensile strength after aging at 150°C for 3d). In addition, introducing a 10-phr glass flake into EPDM wire clamp rubber improved the grip force by 83%. The improvement mechanism may be attributed to the increased compression stress of wire clamp rubber on cable and the restricted slippage of rubber molecular chains.

Flexible Electromagnetic Tactile Sensor Based on Double‐Layer High‐Density MEMS Coils and Tilted Magnetic Column Array

AbstractWith the rapid development of wearable devices, tactile sensors have received extensive attention as supplements to vision and hearing. However, it remains challenging for a single tactile sensor to generate distinguishable electrical signals when receiving mechanical stimuli in different directions. Herein, a novel flexible electromagnetic tactile sensor (FETS) prepared by combining flexible double‐layer coils and a flexible tilted magnetic column array (TMCA) is presented. Flexible double‐layer high‐density coils are fabricated using the micro‐electromechanical system (MEMS) technology. The turns of the coil (1 × 1 cm) are 100, while both the line width and spacing of turns are 40 µm. TMCA is prepared using a template and magnetized along the axis direction. When a pulling force or pressure is applied to the TMCA, the magnetic flux decreases or increases correspondingly, allowing the FETS to accurately distinguish stimuli and produce different signals (−/+ or +/−). The FETS presents a sensitivity of up to 21.7 µV kPa−1 (0.05–10 kPa), a minimal magnetic field detection limit of 10 mT, a low‐pressure detection limit of 5 g, and good repeatability (5000 cycles). Additionally, the FETS is applied in robotic tactile testing, Morse code, and noncontact magnetic field recognition. It has potential applications in the Internet of Things (IoT) and information communication.

THz active modulation device by electric field turned modulation characteristics of titanium sulfide nanofilm device

AbstractAn effective approach to manipulate terahertz (THz) waves involves the utilization of a device structure. In this particular investigation, we have successfully fabricated a SnS2 nanofilm device using femtosecond laser direct ablation. The passive and active polarization‐sensitive characteristics of the SnS2 nanofilm device were examined within the THz frequency range, employing different line spaces of 500, 600, and 700 μm. The combination of the device effect and SnS2 absorption led to an enhanced passive polarization modulation. Moreover, when an external electric field was applied to the SnS2 nanofilm device along the device line, persistent switching and linear modulation of THz wave transmission were observed. These findings indicate that the integration of material properties and device structure in this SnS2 device renders it highly suitable for applications in ultrafast THz switches, filters, and modulation devices.

Line-Spacing-Multiplied Optical Frequency Comb Generation Using an Electro-Optic Talbot Laser and Cross-Phase Modulation in a Fiber

An optical frequency comb (OFC) generator based on an electro-optic Talbot laser and cross-phase modulation (XPM) in a high nonlinear fiber (HNLF) is designed and demonstrated. The Talbot laser is an electro-optic frequency shifting loop that is used to produce repetition rate-multiplied pulses, and these pulses work as a pump signal that induces the XPM process in the HNLF to modulate the phase of a probe signal. At the output of the HNLF, OFCs with a multiplied line spacing can be generated. The effects of the pump power and the HNLF length on the performance of the generated OFCs are theoretically analyzed. In the experiments, the line spacing of the generated OFCs is multiplied to be 10 GHz, 15 GHz, and 20 GHz with a factor of 2, 3, and 4, respectively. The center of the OFCs is tuned in a 4 nm range by adjusting the wavelength of the probe signal.

Modern digital hydrography and the new international hydrographic organisation bathymetric survey standards

The current state of the International Hydrographic organization bathymetric survey Standards S44 (6.1.0) is examined in this study. The introduction of the S44 survey Standards fourth edition in 1998 heralded the beginning of a new era of modern digital hydrography based on the concept of the survey orders resulting from implementation of the Global Navigation Satellite Systems of positioning and hydrographic information systems. The fundamental changes between the 4th and 6th editions of the Standards for Hydrographic Surveys (S-44) are described. The differences between the 5th and 6th editions of the Standards for Hydrographic Surveys (S-44) are evaluated. Particular attention is paid to the conceptual evolution of such definitions as “bathymetric model” and “ features detection”. The main new S44 (6.1.0) survey Standards paradigm became the concept of “bathymetric coverage” and the rejection of the “ full sea floor coverage” concept which was introduced in the previous 5th edition. Introducing the “bathymetric coverage” and “ feature search” notions in the 6th S44 (2022) survey Standards provides the possibility to avoid the implementation of such previously important hydrographic definition as “line spacing”. It is especially emphasized that the introduction and combined application of such definitions as “bathymetric coverage”, “ feature detection” and “ feature search” necessitate the usage in the 6th S44 (2022) survey Standards of the new special tool named “specification matrix”. This tool is important for hydrographic survey drafting taking into consideration the various stakeholder requirements as well as providing a short hydrographic survey description. The introduction of gridding concept in hydrography provided in the S44 (6.1.0) survey Standards for the first time is also mentioned. Critical comments on the interpretation of gridding methods provided in the annex D which are not considered as the part of the Standards are presented. Some recommendations concerning general quality control requirements and survey posteriori quality control provided in the annex C and B are also commented on. It should be especially emphasized that three last editions of S44 Standards use the “standard deviation” term without specifying its confidence level for position uncertainty (Total Horizontal Uncertainty — THU) calculation. The position uncertainty (2D) quantities are stated as “standard deviation” multiplied by coefficient 2.45. The “standard deviation” term needs additional explanation and clarification; it should not be confused with the widely used term «position standard deviation =distance root mean squared». It is also pointed out the insufficient study of the 3D hydrographic technology provisions presented in the 6th S44 survey Standards edition associated with the alternative method of sea level correction determination based on the precise ellipsoid (geodetic) heights measurements of the tide gauges benchmarks and chart datum using GNSS observations. The necessity of inclusion of the requirements for survey posteriori quality control as the result of survey data post-processing, using statistical comparison of check lines crossing the regular lines, is substantiated. Finally, the urgency of developing new Russian hydrographic standards and specifications based on IHO S44 (6.1.0) on the basis of modern technology is emphasized.

Parallel Grooved Microstructure Manufacturing on the Surface of Si3N4 Ceramics by Femtosecond Laser.

Machining special microstructures on the surface of silicon nitride ceramics helps improve their service performance. However, the high brittleness and low fracture toughness of silicon nitride ceramics make it extremely difficult to machine microstructures on their surface. In this study, a femtosecond laser is used to machine parallel grooved microstructures on the surface of silicon nitride ceramics. The effects of the laser polarization angle, laser single pulse energy, scanning line spacing, and laser scan numbers on the surface morphology and geometric characteristics of grooved microstructures are researched. It is found that a greater angle between the direction of the scanning path and laser polarization is helpful to obtain a smoother surface. As the single pulse energy increases, debris and irregular surface structures will emerge. Increasing the laser scan line spacing leads to clearer and more defined parallel grooved microstructures. The groove depth increases with the increase in the scan numbers. However, when a certain number of scans is reached, the depth will not increase further. This study serves as a valuable research foundation for the femtosecond laser processing of silicon nitride ceramic materials.

Improving Electromigration Resistance of Fine‐Pitch Redistributed Layer Using Graphene‐Doped Twinned Copper Composites

The electromigration (EM) behavior of graphene‐doped twinned copper composite (GC–Cu) and nanotwinned copper (NT–Cu) redistributed layers (RDLs) are investigated. Firstly, the GC–Cu has longer lifetimes under various test conditions. For example, the GC–Cu RDL took 291 h to reach a 20% resistance increase, while the NT–Cu RDL took 117 h under the same condition of 120 °C and 106 A cm−2. Secondly, thinner oxidation layer and slighter voiding phenomena are detected on GC–Cu RDLs. When the line width and spacing (L/S) of RDL decreased from 20/20 μm to 10/10 μm, new failure modes, i.e., fracture of oxide layer, separation between the oxide layer and copper matrix are also detected, demonstrating the increasing thermal mismatch. Combined with the finite element analysis (FEA), there is simultaneous current aggregation and stress concentration around the voids, which should further cause the degradation of RDL. Above all, this study gives insights into the material design in the fine‐pitch RDL structure.

Agent-Based Principal Strips Modeling for Freeform Surfaces in Architecture

The principal curvature (PC) of a freeform surface, as an important indicator of its fundamental features, is frequently used to guide their rationalization in the field of architectural geometry. The division of a surface using its PC lines into principal strips (PSs) is an innovative way to break down a freeform surface for construction. However, the application of PC networks in architectural design is hindered by the difficulty to generate them and flexibly control their density. This paper introduces a method for PS-based reconstruction of freeform surfaces with different umbilical conditions in the early stages of design. An agent-based modeling approach is developed to find the umbilics and increase the degree of control over the spacing of PC lines. This research can effectively expand the application range of PS-based surface reconstruction methods for freeform architectures.

Effect of process parameters on the corrosion kinetics and mechanism of nanosecond laser surface structured titanium alloy (Ti6Al4V)

In this study, laser surface structuring (LSS) of Ti6Al4V was carried out using an Nd:YLF laser with a second harmonic wavelength of 527 nm and a pulse duration of 100 ns at varied laser fluence, scan speed, and line spacing. A detailed study of the effect of process parameters on surface topography, microstructure, composition, phase, contact angle, electrochemical behavior, and bioactivity was undertaken. Nanosecond pulsed laser irradiation with overlapping resulted in the formation of linear continuous grooves on the surface due to ablation/evaporation of materials. There is the formation of oxides of titanium (TiO2 and Ti2O3) whose mass fractions varied with process parameters. The average microhardness of the laser-structured region was improved (393 VHN - 535 VHN) as compared to the as-received Ti6Al4V (303 VHN). The contact angle of simulated body fluid (SBF) against the structured surface (58°- 123°) showed increased contact angle as compared to as-received samples (50°). The laser surface structuring exhibited a superior corrosion resistance property (in SBF) as compared to as-received Ti6Al4V. The mechanism of corrosion behavior was established by electrochemical impedance spectroscopic study (in SBF). The optimum process parameter for the LSS of Ti6Al4V with enhanced hardness and corrosion resistance was derived. The LSS surface processed under the optimum parameters measured by immersing in SBF revealed a higher deposition of calcium phosphate as compared to the as-received Ti6Al4V.