Strip Width Research Articles

Tunable enhancement of the cylindrical Luneburg lens focusing ability with the aid of a conformal graphene strip

We consider the plane wave focusing characteristics of the layered cylindrical Luneburg lens equipped with a conformal strip of graphene, in the H-polarization case. The angular width and location of the strip is arbitrary, and its surface impedance is characterized with the aid of the quantum-physics Kubo formalism. We use a mathematically accurate full-wave analytical regularization technique, which is based on the explicit inversion of the problem static part and yields a Fredholm second-kind matrix equation. This guarantees the convergence of the resulting meshless numerical algorithm. We compute the focusing ability of a microsize lens as a function of the frequency in the wide range up to 60 THz. This analysis shows that a graphene strip, placed into the focal area of the Luneburg lens, enhances its focusing ability at the resonance frequency of the strip plasmon mode proportionally to the quality factor. This frequency is defined by the strip width and is tunable with the aid of graphene’s chemical potential.

Strip cropping increases yield and revenue: multi-year analysis of an organic system in the Netherlands

Intercropping is proposed as a promising strategy to meet future food demand while reducing agriculture’s environmental impact by re-diversifying agricultural fields. Strip cropping, a form of intercropping, has a potential to simultaneously deliver multiple ecosystem services including productivity, while facilitating management as strip width can be adjusted to the working width of available machines. While the yield performance of strip cropping systems is influenced by the interaction between neighboring crops, to date, empirical studies on the performance of various crop combinations in strip cropping systems are limited. Here we used three-year data (2020–2022) from a 64-ha organic strip cropping system in the Netherlands to (1) evaluate the effects of crop neighbors and strip cropping on yield and (2) explore if optimizing the allocation of crop neighbors in alternative strip cropping configurations can improve yield and revenue performances. We analyzed the edge effect and strip cropping effect on yield of six crops grown in strips, each neighboring a total of five crops. The yield data was then used to evaluate the performance of the current and alternative strip configurations in terms of LER and relative revenue. Results showed that except for the positive effect observed on potato when neighboring celeriac or broccoli, edge effects lacked statistical significance. Strip cropping effect varied per crop: positive for faba bean and parsnip, neutral for celeriac and potato, and negative for oat and onion. Analysis across crops showed an overall significant positive strip cropping effect on yield. These findings highlighted the value of analysis at the cropping system level in developing designs aimed at unlocking the potential of strip cropping. The positive but variable strip cropping effects observed in the current experimental design and the two alternative configurations suggests prioritizing an overall increased crop diversity over optimizing their spatial arrangement. While we demonstrated increased productivity with strip cropping, further research is needed to expand the database on optimal crop combinations, extending the evaluation beyond yield and revenue performances to facilitate broader adoption of strip cropping in the Netherlands and Western Europe.

Image Restoration of Electrical Well Logging Based on Fourier Convolution

Imaging logging is an important technical means in logging evaluation of complex reservoirs. Through imaging logging, a two-dimensional image of the resistivity distribution around the well can be obtained, which can be used to evaluate the development of well wall fractures and caves and the formation sedimentary structure. However, due to the characteristics of resistivity imaging logging instruments, blank strips will appear on the resistivity logging image, which increases the difficulty of computer processing of electrical imaging data. The current image repair method and the existing neural network image repair method are not effective enough when the part to be filled is large. Therefore, there is an urgent need for an intelligent repair method based on deep learning. Based on a fast Fourier convolution-based imaging logging image blank strip filling network, this paper constructs the electrical imaging logging images of the southwest oil and gas field as a data set, and trains a new deep learning algorithm for intelligent filling of blank strips in imaging logging images based on fast Fourier convolution. The time of various algorithms is compared. The results show that the algorithm has a better repair effect in imaging logging images with large strip widths, and the repair efficiency is significantly improved. This method can realize the rapid, accurate and intelligent repair of blank strips in imaging logging, achieve the rapid generation of full-borehole images, and solve the difficulties in obtaining full-borehole images.

GENERAL RECOMMENDATIONS FOR THE SEARCH AND DETECTION OF EXPLOSIVE ORDNANCE IN THE CONDITIONS OF HIGH CONTAMINATION OF THE AREA WITH METAL FRAGMENTS

Currently, the enemy is using new mining tactics, when other sources of danger are additionally installed during mining, in particular with anti-personnel mines (APMs). This leads to accidents among sappers during operational demining. Therefore, there is an urgent problem of determining the procedure for searching for UXOs when the area is highly contaminated with metal fragments. An analysis of specialized literature has shown that the problem of searching, detecting and identifying UXOs both on land and in the water is the subject of close attention by both military specialists and researchers. Considerable attention has been paid to the testing and evaluation of metal detectors. However, the issue of searching for UXOs in highly contaminated areas with metal fragments, especially in areas of combat operations, has not been covered. The purpose of this article is to determine the procedure for organizing and conducting search and detection operations for UXOs in a highly contaminated area with nearby mines and metal fragments. At the same time, the risk of an emergency should be minimized. In this study, taking into account the fact of an increase in the number of accidents among deminers, it is proposed to adhere to the following recommendations when searching for and detecting UXOs in a highly contaminated area with metal fragments every working day before the start of the search for UXO, calibrate the metal detector to ensure confidence in the ability of the metal detector to distinguish between signals from the source of the hazard and nearby targets. Record the calibration of each metal detector in the calibration log; it is recommended to carry out work on the search for UXO using a metal detector within a 1-meter wide clearance strip using a base rail; it is recommended to mark the source of the hazardous signal along the edge of the search element of the metal detector, rather than determine the center of the signal; when searching for UXOs with high contamination of the area with metal fragments, it is recommended not to use probes, but to excavate the soil around the marked UXO using a shovel (scraper).

Flatness jump phenomenon in cold-rolled steel strip with high temperature: Root cause and solution

The steel strip produced in the 20-high cold rolling mill has the characteristic of high temperature in a certain factory, and a rare strip flatness phenomenon occurs in the fourth pass, different from the common flatness defects, the flatness value of each position in the strip width shows an irregular and drastic fluctuation state along with time, and it is called the flatness jump phenomenon, which seriously affects the stability of the rolling process and the production efficiency. Aiming at this problem, a method combining the rolling experiment with the numerical simulation is used to study its generation mechanism and seek for effective control technique. Through the thermal imaging measurement and the analysis of the production data, the temperature fluctuation in the fourth pass is the main reason for the flatness jump, which is related to the nucleate boiling state when the emulsion impacts on the high-temperature strip surface in the cooling process. Based on the rolling control experiments of different cooling factors, the critical temperature range for the occurrence of flatness jump is determined, which is used for the improvement of cooling technique subsequently, and the range of emulsion exit flow is optimized to 500 L/min ∼ 2050 L/min. The rolling experiment is carried out in the industrial field, it is found that the production process is stable and the flatness jump does not appear, with the small value basically within the range of ± 10 IU, and the scheme is planned for long-term application after a period of optimization, which could ultimately enhance the stability of the rolling process and the performance of finished product. Further, the paradigm and information provided in this work would be beneficial for understanding the formation mechanism of the similar complicated flatness phenomenon in cold rolling and optimizing the industrial applications of cooling technology.

Habitat structure and an introduced predator limit the abundance of an endangered ground-nesting bird.

Understanding the factors that limit the abundance of threatened species is critical for the development of effective conservation strategies. However, gaining such knowledge from monitoring programs and using it to inform decision-making for rare species can be difficult due to methodological issues posed by the problems of distinguishing true absences from false absences and the analysis of datasets dominated by zero counts. The plains-wanderer (Pedionomus torquatus) is a critically endangered ground-nesting bird that occurs in grasslands of southeastern Australia. Decline of the plains-wanderer has been attributed to habitat modification but little emphasis has been placed on the role of introduced predators, such as the red fox (Vulpes vulpes), which have had a devastating effect on small ground-dwelling vertebrates in dryland regions of Australia. Here, we use a 9-year time series of spotlight counts to investigate the impact of vegetation structure and fox presence on plains-wanderer occupancy and abundance. We used distance sampling to determine the effective strip width for sighting plains-wanderers during spotlight surveys. We then used a hurdle model approach whereby binomial generalized additive models were fitted to presence/absence data within the effective strip-width across all sites and negative-binomial models were fitted to an index of abundance at sites where plains-wanderers were observed. Plains-wanderer occupancy and abundance fluctuated markedly through time. Where foxes were absent, occupancy (but not abundance) of plains-wanderers showed a humped relationship with grass height with an optimal height between 50 and 150 mm. Where foxes were present however, this relationship broke down and plains-wanderers were rarely recorded. Our results suggest that plains-wanderers should benefit from management strategies that maintain grass height at optimal levels and exclude foxes or effectively suppress their populations. A key message from this study is that if statistical analyses of data generated by monitoring programs for rare species are intended to inform management decisions by identifying relationships between threatened species and drivers of their abundance, there should be consideration of analytic approaches that account for true and false zeroes, high prevalence of zeroes, and the possibility of nonlinear responses.

Impact of Nickel Strip Configurations on Resistance and Voltage Drop in Lithium Ion Battery Packs

The impact of nickel strip designs on the resistance and voltage drop in lithium ion battery packs is examined in this study. In a series parallel battery pack configuration, the effectiveness of coated and pure nickel strips is assessed, with particular attention paid to how they influence voltage drop, internal resistance, and overall efficiency. Each of the 24 series and 3 parallel cells that make up the battery pack has an internal resistance of 6 mΩ. Two configurations are analyzed: one utilizing pure nickel strips and another with coated nickel strips. The resistivity, cross sectional area, and length of the material are used to compute the equivalent resistance of the nickel strips for each arrangement. Voltage dips at a load current of 50A are determined to compare the performance of both strip. The study also looks at the voltage drop at key locations in the battery pack, including particular bent strips. The findings show that the coated nickel design displays a larger resistance (0.237Ω) and voltage drop (11.735V) than the pure nickel configuration, which has a lower total resistance (0.048Ω) and voltage drop (2.82V). Evaluation of the voltage drop during charging is also done for charging currents of 6A and 10A, demonstrating that the pure nickel arrangement allows for more efficient charging. One of the main elements affecting battery pack performance is internal resistance, which has a direct impact on the system's voltage drop and overall energy efficiency. The thickness, width, resistivity, and number of parallel strips utilized in this nickel strip material all have a major effect on the battery pack's total resistance. Because of this, the nickel strip design can improve or worsen the pack's power delivery, particularly in high load scenarios.

Light scattering by Möbius particles

Using the Discrete-Dipole Approximation (DDA) we study scattering-angle dependences of the orientationally averaged Mueller matrix elements for small Möbius particles with different chirality. A Möbius particle is a strip of a certain width and thickness, the ends of which are attached to each other after twisting one of them at an angle by a multiple of □. The Mueller matrices Mik for such particles have 16 non-zero elements. The scattering-angle dependences of the intensity M11, linear polarization degree (-M12/M11), and Circular Intensity Differential Scattering (CIDS = -M14/M11) show their sensitivity to the refractive index and number of the strip twisting. For instance, the CIDS depends significantly on the complex part of the refractive index. Particles with more twists show a decrease in the maximum value of the positive branch of linear polarization and an increase in the width and minimum of the negative branch. The twist parameter's influence on CIDS is non-monotonic, initially increasing and then approaching zero with further twisting.

Novel 3D FRP system used for more effectively and readily strengthening of precast concrete elements

The burgeoning precast concrete market necessitates innovative strengthening solutions to ensure the durability and safety of precast elements. This study presents a 3D Fiber Reinforced Polymer (FRP) system designed to reinforce precast concrete elements, providing a more effective and efficient method compared to traditional Externally Bonded (EB) and Near Surface Mounted (NSM) FRP techniques. The system utilizes extended FRP strips that function as bent anchorages, U-wraps for anchorage protection, and additional FRP patches to prevent anchorage cutoff at bent corners. A comprehensive experimental campaign involving 33 specimens assessed the system's performance, demonstrating significant improvements in flexural and shear capacities with minimal surface preparation requirements. The experiments included varying strip widths and anchorage configurations to optimize the system's effectiveness. Numerical models were developed to simulate the flexural behavior of the 3D FRP reinforced elements, accurately predicting load-deflection responses and failure modes. Both experimental and numerical results suggest that the 3D FRP system not only enhances the load capacity and structural integrity of precast concrete elements but also simplifies the installation process, offering a promising solution for the construction industry. The findings also offer practical guidelines for the design and fabrication of 3D FRP reinforced concrete elements, contributing to a more sustainable and economical construction approach.

The Functional Outcome of Boswarth Technique in terms of Ability to Stand on Tip Toes of Affected Side and Power of Planter Flexion

Background: Bosworth healed an Achilles tendon rupture by wrapping a wide strip of the proximal aponeuros is around the proximal and distal tendon stumps. Objective: To find out the functional outcome of Boswarth Technique in terms of ability to stand on tip toes of affected side and power of planter flexion. Methodology: DMCH conducted this prospective research from July 2006 to December 2007. Non-randomized purposive sampling chose 20 DMCHF outpatients.18 patients were first studied. Data was hand-edited. After that, SPSS data was entered. Results: The youngest patient was 17 years old and the oldest 47 years old.5:1 male-female ratio. Nearly 40% of patients were injured by an overhanging toilet pan, 27.8% by traumatic rupture, and 11.1% by a sharp weapon. The median injury level was 3.5 cm above the tendoachilles insertion, whereas the lowest and highest were 2.5 and 6 cm. Objective examination shows 45% of patients had excellent functional outcomes, 38.9% good, 11.1% fair, and 5.6% poor. This study's results were good in 83.3% and unsatisfactory in 16.7%. Conclusion: The Bosworth approach was simple to learn, making it potentially appropriate for foot and ankle surgeons with less training.

ТРИ САРМАТСКИХ ПОГРЕБАЛЬНЫХ КОМПЛЕКСА ИЗ СТЕПНОГО КРЫМА

The work analyzes three recently discovered burial monuments of the 1st century BC – mid (?) 1st century AD in the Steppe Crimea. Their distinctive features are the use of an older kurgan for burial, the predominant orientation of the deceased to the northern sector, the insignificant depth of the burial, the paucity of grave goods, etc. – typical for early Sarmatian burials of the Northern Black Sea region. Therefore, the complexes under consideration should be correlated specifically with this cultural group. It is important to emphasize that, although large-scale field research in recent years has covered a significant part of the steppe space of the Crimean Peninsula, passing through it in a wide strip from east to west, Sarmatian monuments have not been identified in most of this territory. The newly opened complexes are located on the Kerch Peninsula and near it, i.e. in those areas in which Sarmatian burials were previously known. This only confirms the conclusion already made about the location of Sarmatian burials in the Steppe Crimea only in a narrow strip along the northern and north-eastern borders of the region, along the coast of the Black Sea and Sivash. This location, apparently, marks the path of the ancient nomads from the Dnieper region – one of the main areas of their settlement – to the ancient centers of the Crimean Peninsula, in particular Panticapaeum, to carry out trade and other relationships.

Novel spectral methods for shock capturing and the removal of tygers in computational fluid dynamics

Spectral methods yield numerical solutions of the Galerkin-truncated versions of nonlinear partial differential equations (PDEs) involved especially in fluid dynamics. In the presence of discontinuities, such as shocks, spectral approximations develop Gibbs oscillations near the discontinuity. This causes the numerical solution to deviate quickly from the true solution. For spectral approximations of the inviscid Burgers equation in one-dimension (1D), nonlinear wave resonances lead to the formation of localised oscillatory structures called tygers in well-resolved areas of the flow, far from the shock. Recently, the author of [1] has proposed novel spectral relaxation (SR) and spectral purging (SP) schemes for the removal of tygers and Gibbs oscillations in spectral approximations of nonlinear conservation laws. For the 1D inviscid Burgers equation, it is shown in [1] that the novel SR and SP approximations of the solution converge strongly in L2 norm to the entropic weak solution, under an appropriate choice of kernels and related parameters. In this work, we carry out a detailed numerical investigation of SR and SP schemes when applied to the 1D inviscid Burgers equation and report the efficiency of shock capture and the removal of tygers. We then extend our study to systems of nonlinear hyperbolic conservation laws, such as the 2×2 system of the shallow water equations and the standard 3×3 system of 1D compressible Euler equations. For the latter, we generalise the implementation of SR methods to non-periodic problems using Chebyshev polynomials. We then turn to singular flow in the 1D wall approximation of the 3D-axisymmetric wall-bounded incompressible Euler equation [2]. Here, in order to determine the blowup time of the solution, we compare the decay of the width of the analyticity strip, obtained from the pure pseudospectral method (PPS), with the improved estimate obtained using the novel spectral relaxation scheme.

Evaluating mechanical benefit of wedge osteotomies in endoscopic surgery for sagittal synostosis using patient-specific 3D-printed models.

Endoscopically assisted sagittal strip craniotomy with subsequent cranial orthosis is a frequently used surgical approach for non-syndromic sagittal synostosis. Originally, this technique involved a wide sagittal strip craniectomy with bilateral wedge osteotomies. More recent studies suggest omitting wedge osteotomies, achieving similar outcomes. The controversy surrounding wedge osteotomies and our efforts to refine our technique led us to create models and evaluate the mechanical impact of wedge osteotomies. We conducted a 3D-print study involving preoperative CT scans of non-syndromic scaphocephaly patients undergoing minimally invasive-assisted remodelation (MEAR) surgery. The sagittal strip collected during surgery underwent thickness measurement, along with a 3-point bending test. These results were used to determine printing parameters for accurately replicating the skull model. Model testing simulated gravitational forces during the postoperative course and assessed lateral expansion under various wedge osteotomy conditions. The median sagittal strip thickness was 2.00mm (range 1.35-3.46mm) and significantly positively correlated (p = 0.037) with the median force (21.05 N) of the 3-point bending test. Model testing involving 40 models demonstrated that biparietal wedge osteotomies significantly reduced the force required for lateral bone shift, with a trend up to 5-cm-long cuts (p = 0.007). Additional cuts beyond this length or adding the occipital cut did not provide further significant advantage (p = 0.1643; p = 9.6381). Biparietal wedge osteotomies reduce the force needed for lateral expansion, provide circumstances for accelerated head shape correction, and potentially reduce the duration of cranial orthosis therapy.

Characterization of Jurassic mudstones of the Northwest Caucasus as a raw material for clinker tile production

The article characterizes Jurassic mudstones of the North-West Caucasus as a potential raw material for the production of clinker tiles with water absorption of less than 3%. It is noted that traditional for the south of Russia raw materials for the production of ceramic bricks and tiles in the last centuries were various types of loams, which are widely distributed almost throughout the territory. However, for a number of reasons, they cannot be considered as raw materials for the production of clinker tiles, for which there has been a steady demand in recent years, especially on the Black Sea coast. Geographically, the Jurassic sediments in the Krasnodar region are traced in a wide strip (50–100 km) at a distance of 20 to 60 km from the coast. These are the oldest rocks in the region. The thickness of numerous mudstones varies from a few to many tens of meters. The chemical composition of mudstones is characterized by the content of aluminum oxide from 17 to 22 %, increased content of potassium oxide and iron oxides. The mineral composition is represented by hydrous mica, kaolinite and chlorite with admixture of quartz and feldspars. Pre-firing properties of argillites can be regulated by the degree of grinding. In terms of sinterability, argillites are qualified as a strong-medium sintering raw material of low-temperature sintering with high strength of ceramic stone. The results and analysis of the obtained data allow us to assert that the Jurassic mudstones of the North-West Caucasus are potentially suitable raw materials for production of clinker tiles with a wide range of physical and technical properties using a simplified technology.

Small Magellanic Cloud Cepheids Observed with the Hubble Space Telescope Provide a New Anchor for the SH0ES Distance Ladder

We present phase-corrected photometric measurements of 88 Cepheid variables in the core of the Small Magellanic Cloud (SMC), the first sample obtained with the Hubble Space Telescope's (HST) Wide Field Camera 3, in the same homogeneous photometric system as past measurements of all Cepheids on the SH0ES distance ladder. We limit the sample to the inner core and model the geometry to reduce errors in prior studies due to the nontrivial depth of this cloud. Without crowding present in ground-based studies, we obtain an unprecedentedly low dispersion of 0.102 mag for a period–luminosity (P–L) relation in the SMC, approaching the width of the Cepheid instability strip. The new geometric distance to 15 late-type detached eclipsing binaries in the SMC offers a rare opportunity to improve the foundation of the distance ladder, increasing the number of calibrating galaxies from three to four. With the SMC as the only anchor, we find H 0 = 74.1 ± 2.1 km s−1 Mpc−1. Combining these four geometric distances with our HST photometry of SMC Cepheids, we obtain H 0 = 73.17 ± 0.86 km s−1 Mpc−1. By including the SMC in the distance ladder, we also double the range where the metallicity ([Fe/H]) dependence of the Cepheid P–L relation can be calibrated, and we find γ = −0.234 ± 0.052 mag dex−1. Our local measurement of H 0 based on Cepheids and Type Ia supernovae shows a 5.8σ tension with the value inferred from the cosmic microwave background assuming a Lambda cold dark matter (ΛCDM) cosmology, reinforcing the possibility of physics beyond ΛCDM.

Data-Driven Interpretable Machine Learning Prediction Method for the Bond Strength of Near-Surface-Mounted FRP-Concrete

The Near-Surface-Mounted (NSM) technique for Fiber-Reinforced Polymer (FRP) strengthening is widely applied in the seismic retrofitting of concrete structures. The key aspect of the NSM technique lies in the adhesive performance between the FRP, adhesive layer, and concrete. In order to accurately predict the bond strength of embedded reinforced NSM FRP–concrete, this study constructs the relationship between the influencing factors of bonding performance and bond strength based on four machine learning (ML) algorithms: Decision Tree (DT), Support Vector Machine (SVM), Random Forest (RF), and eXtreme Gradient Boosting (XGB). A unified and interpretable prediction method for FRP–concrete interface bond strength based on SHAP values and ML algorithms is proposed. The results indicate that the ML models exhibit good predictive performance, with the R2 of the test set ranging from 0.8190 to 0.9621, showing higher accuracy than empirical calculation formulas. Among them, the RF algorithm demonstrates the highest overall accuracy and optimal performance. Additionally, the SHAP (Shapley additional explanations) method quantitatively confirms that the width of the FRP strip has the most significant impact on bond strength. The newly developed hybrid ML model has the potential to become a new choice for accurately assessing the bond strength of NSM FRP strengthening technology.

Solution of a Dugdale–Barenblatt crack in an infinite strip by a hyper-singular integral equation

This work treats the case of a Dugdale–Barenblatt crack within an infinite strip through the resolution of a hyper singular integral equation. The crack is perpendicular to the strip boundaries and located at its center. The solution approach is based on second order Chebyshev polynomials and requires meticulous treatment of the jump discontinuities within the loading distribution along the crack faces. The relationship between the width of the strip and the length of the cohesive zone has been established. The variation in applied load with the increase in crack length, considering different ratios of the initial crack length to the strip width is illustrated. Furthermore, the crack propagation is simulated. Validation of our approach is achieved through comparison with both the infinite medium case and the work of H. Tada et al. “The Stress Analysis of Cracks Handbook, Del Research Corporation, Hellertown, Pennsylvania. 1973”.

Predicting the roadway width of forest roads by means of airborne laser scanning

Modern forestry relies on an extensive network of well-maintained forest roads. However, the trafficability of forest roads can be limited by poor construction or by insufficient load-bearing capacity caused by, for example, weather conditions. In all forestry operations, the forest roads should be able to support heavy vehicles during the transport of roundwood and harvesting machinery, so logistics must be carefully planned to ensure good road trafficability. To facilitate this planning, it is necessary to know the various characteristics of the forest road in terms of its width, structure and load-bearing capacity. Obtaining such information using remote sensing data would be beneficial. In this study, we used airborne laser scanning (ALS) data to assess the width of the roadway on forest roads. We developed several algorithms that were used to assess roadway width based on the cross-sectional data (derived with ALS) of the roads in 8-m long segments. The ALS echoes within the segments were classified into 20 cm wide strips which the algorithms then analyzed in a stepwise manner. Both height and intensity information from the ALS data were utilized. The algorithm results were then used as predictors in linear models to predict the roadway width. The main focus was on the road level, i.e., aggregated values from 25 different roads were used in model fitting. In terms of root mean square error (RMSE) values, accuracies of approximately 20–30 cm (or 7–10 %) were obtained for the predicted roadway widths with a separate validation data. This level of accuracy can be considered adequate given the characteristics of the ALS data used in the modelling. The results indicate that the presented approach has potential for practical applications to predict the width attributes of forest roads.

Study on 1550 nm Human Eye-Safe High-Power Tunnel Junction Quantum Well Laser.

Falling within the safe bands for human eyes, 1550 nm semiconductor lasers have a wide range of applications in the fields of LIDAR, fast-ranging long-distance optical communication, and gas sensing. The 1550 nm human eye-safe high-power tunnel junction quantum well laser developed in this paper uses three quantum well structures connected by two tunnel junctions as the active region; photolithography and etching were performed to form two trenches perpendicular to the direction of the epitaxial layer growth with a depth exceeding the tunnel junction, and the trenches were finally filled with oxides to reduce the extension current. Finally, a 1550 nm InGaAlAs quantum well laser with a pulsed peak power of 31 W at 30 A (10 KHz, 100 ns) was realized for a single-emitter laser device with an injection strip width of 190 μm, a ridge width of 300 μm, and a cavity length of 2 mm, with a final slope efficiency of 1.03 W/A, and with a horizontal divergence angle of about 13° and a vertical divergence angle of no more than 30°. The device has good slope efficiency, and this 100 ns pulse width can be effectively applied in the fields of fog-transparent imaging sensors and fast headroom ranging radar areas.

Lattice boltzmann investigation of droplet interactions with non-uniform chemically patterned surfaces

In this study, we employed a non-orthogonal, three-dimensional, multi-relaxation-time pseudo-potential lattice Boltzmann method, and investigate the behaviors of droplets impacting chemically patterned surfaces. We considered two interfaces: a hydrophobic/neutral strip on a hydrophilic wall (surface A), and a hydrophilic strip on a hydrophobic wall (surface B). The dynamics of impact, including the evolution of the morphology and the droplet spreading factor, were investigated under the influence of the difference in wettability, Weber number (We), and strip width. An increase in the wettability difference of surface A delayed droplet detachment and reduced the amplitude of oscillations, where this can be attributed to the surface tension and viscous dissipation, which had more time to weaken the strength of the jet. The magnitude of droplet detachment time initially increased with We but eventually decreased. As We is further increased, the ratio of viscous loss to the initial kinetic energy of the droplet is decreased and resulted in a shorter detachment time. The unbalanced Young's force significantly affected the evolution of the droplet on surface B. The mass of the droplet accumulated near the borderline of the strip and expanded along the y-axis under the influence of the inertial force, where this led to a larger spreading factor along the y-axis. In addition, the mass of the droplet on the hydrophobic wall affected the strength of the unbalanced Young's force. As the strip width increased, the spreading factor initially increased but then decreased along the y-axis owing to the combined action of inertial forces.