Minimum Track Research Articles

A parametrization study of TEULM’s image reconstruction performance

Time efficient ultrasound localization microscopy (TEULM) allows imaging the microvascular structures with reduced frame rates compared to standard ULM. The quality of reconstructed images relies on different parameters. In this study, we aim at understanding the links between TEULM performance and three key parameters: SVD k-value (representing the number of components considered as noise), the maximum linking distance (indicating the assumed maximum distance that a microbubble can cover between two successive frames), and the minimum length of a track. We generated TEULM density and dynamics maps, singularly varying these three parameters. Next, we evaluated the quality of TEULM images by means of a root mean squared error (RMSE), dice score, and Fourier ring correlation (FRC) analysis. A publicly available preclinical in-vivo dataset was used for this study. Results demonstrate that minimum track length and k-value have the greatest impact on both density and dynamic maps RMSE, whereas the minimum linking distance is the key factor influencing the dice score. Additionally, the relationship between these parameters and metrics is non-linear. Furthermore, the resolution measured by the FRC is negatively affected by increasing the SVD k-value and by increasing the maximum linking distance but positively affected by increasing the minimum track length.

Optimization of Laser Direct Structuring Process Parameters for Material Extrusion of Polycarbonate

Laser direct structuring (LDS) is critical in the integration of circuits onto 3D‐shaped plastic parts, such as antennas and radio frequency components. The LDS process encompasses three stages: deposition of 3D parts, laser structuring, and metallization. While laser‐direct structurable parts have been manufactured through plastic injection molding, material extrusion (MEX) is a favored additive manufacturing process for economic low‐volume production and fast prototyping advantages. Although injection‐molded LDS literature is available, 3D‐printed laser‐direct structured components merit further investigation. This study focuses on the MEX of catalyst‐loaded polycarbonate (PC) parts and its LDS process. The parameters from the nanosecond fiber laser, including scan speed, power, and frequency, are thoroughly analyzed to understand the surface property changes and metallization performance of the printed PC parts. The single scan track width, which corresponds to the accuracy of conductive path width and metallization thickness, is employed to elucidate the findings. A process map is built to keep the track width constant aimed at enhancing the uniform metallization of intricate components. Thresholds are established, identifying a minimum track width of 22.1 μm and metallization thickness of 2.5 μm. These delineate clusters of process parameters that yield conductivity levels suitable for various applications.

Numerical study of thermocapillary migration of a droplet on an oleophilic track

The thermocapillary migration dynamics of a droplet with a non-circular footprint on an oleophilic track is studied numerically. Three-dimensional simulations showed that reducing the width of the oleophilic track improves the droplet migration velocity only upto a specific track width when compared to the change in velocity of a droplet with circular footprint. Further decrease in track width is seen to depreciate the enhancement in migration velocity. The spread length of the droplet on the oleophilic track is also observed to have a similar variation with track width. The two trends are related because the temperature difference in the droplet, which scales with spread length, determines the driving force governing the migration velocity characteristics. Further, a parametric study is performed to assess the migration behaviour on oleophilic tracks with change in substrate temperature gradient, droplet volume and contact angles within and outside the track. The influence of change in these parameters on the variation in enhancement in spread length and corresponding track width is also investigated. The study identified trends in the minimum track width that may be used to improve migration characteristics, as well as the order of enhancement that can be noticed with changes in each parameter.

How many vs which: On confined track selection criteria for apatite fission track analysis

Inter-laboratory and inter-analyst experiments on confined fission-track length measurements in apatite have reported considerable variation, which can be attributed primarily to differences in analyst decision-making. Here we explore how different etching sequences, track selection approaches, and analytical methods influence track length and density measurements. The first experiment focuses on analyst judgement across different track selection criteria and light sources, and variation in effective etching time, using moderately annealed induced tracks in Durango apatite. Tracks are selected either with the usual approach of only choosing well-etched tracks, which we term the sufficiently-etched criterion, or a more relaxed criterion of simply being measurable without judging how etched they are. For the sufficiently-etched criterion, we separately analyze tracks found using exclusively reflected or transmitted light. We then follow the evolution of all selected tracks through further etching steps, and compare results based on length, angle, and dip, and placed in the context of a variable along-track etching rate model. All step etches show evidence of along-track etching rate falling from core to tip, and tracks measured using the sufficiently-etched criterion are slightly under-etched compared to the full latent track zone with enhanced etching rate. Minimizing effective etch time variation, by only using tracks selected after 10 s of etching, produced tracks averaging ~0.3 μm longer after 20 s than tracks selected using the sufficiently-etched criterion. Ensuring a minimum track etching time by first selecting measurable tracks after 20 s and etching for 10 s more produced tracks ~0.4 μm longer, but correctable to the latent length. Utilizing exclusively transmitted light diminishes mean track dip, and likely reflects lower efficiency in finding dipping tracks. In the second experiment, we repeatedly measure dipping confined tracks at various stages of annealing with and without using a cross-sectional view of the track, finding that the latter avoids an increase in scatter with increasing dip. We propose a two-step etching procedure that may provide more plentiful and reproducible data by reducing the impact of human decision-making, while still being relatable to published annealing data sets.

Phased array calibration system with high accuracy and low complexity

This paper presents a highly efficient phased array calibration system for phase and magnitude error correction. The proposed calibration system is based on far-field scanning of the array antenna under test at factory level. Since the proposed structure requires a magnitude detection only for vector calibration, low circuit complexity can be achieved. Unlike the conventional far-field calibration based on rotating-element electric-field vector (REV) method to find maximum vector-sum point, the proposed system detects the minimum vector-sum point and tracks the behavior of the null point. To verify the feasibility of the proposed system for large-scale array antenna, 4 × 4 phased array antenna is implemented at 5.8 GHz. Then, the proposed method is applied to the phased array antenna and compared with the conventional REV method.

Loop track: an infinite long track model

ABSTRACT This paper developed a track model called the ‘Loop Track’ that had a new function to simulate infinite long tracks without heavy data movement. The model was three-dimensional and considers rails, sleepers, ballast, subballast, and subgrade. Rails were modelled by using the Finite Element Method whilst all other components were modelled as equivalent rigid bodies connected by flexible force elements. The loop or infinite feature of the model was achieved by adding an extra boundary section to link the last node set to the first node set of the original track model. Case studies were conducted to simulate infinite long tracks and variable track conditions, as well as to determine the minimum track length required for different simulations. Results show that the recommended minimum track lengths for the simulated cases were 76 sleepers for vertical track dynamics and 301 sleepers for longitudinal track dynamics.

Compact Uniform Folded Section Rat-Race Couplers with Harmonic Suppression

In this paper, two 50Ω terminated rat-race hybrid couplers based on uniform folded structures are proposed for equal division of power. The proposed designs are of simple in geometry and have an area of only one-fourth of the conventional coupler. The first technique is two-fold double section topology operating at 1.77 GHz designed with the conventional impedance ratio of √2 between port and transmission line which exhibits good in-band characteristics and requires a minimum track width of 0.8 mm. The second technique is stub-loaded double section topology where the novelty lies in deploying impedance matched stubs which avoids high impedance lines by maintaining an impedance ratio less than 2 between port and transmission line. In addition to good passband characteristics, it also suppresses higher harmonics up to 6.3f 0 and requires a minimum track width of 0.41 mm which makes it easy for realization. The bottom line of both designs is to achieve extreme structural simplicity without using high impedance transmission lines of more than 100Ω, narrow tracks less than 0.4 mm, lumped elements, and via holes. The prototype of the proposed coupler is fabricated and the simulated results are validated using measurements.

Design and Simulation of ANFIS based Brushless DC Motor Control

BLDC motor control with ANFIS control methods was investigated and analysed, in this work. The results show that the ANFIS approach is simple, efficient and achieves the desired speed and torque values. The approach was developed and used in both industrial and literary applications. The ANFIS controller was compared with Fuzzy and PI controllers. ANFIS has proved its reliability and good performance. Besides its swift execution, speed control has demonstrated its capability to maintain a minimum cost and commitment track of the target speed values. The method is a basic method with light steps and no reference processing or synchronisation is required.

Оптимизация возвышения наружного рельса в железнодорожных кривых на основе стоимости межремонтного цикла

Objective: To determine the optimal elevation of the outer rail in a curved track section based on technical and economic criteria, calculating the life cycle cost using the methods of life cycle re-source management, risks, and reliability analysis (URRAN methodology). Methods: The authors used multivariate analysis, point estimation, the probability theory and mathematical statistics, the theory of reliability of technical systems, the URRAN methodology, field observations of the condi-tion of the curved track sections and the scope of work during their maintenance. Results: A model of the overhaul cycle of a curved track section has been developed. The dependences of the change in the intensity of the accumulation of faults and the cost of track maintenance during the overhaul cycle on the average values of undamped train accelerations when moving along the sur-veyed sections are presented. The optimal values of undamped acceleration are determined for various operating conditions of railway curves, which provide the minimum track maintenance costs. The authors have found that the minimum cost of the overhaul cycle is the factor for choos-ing the optimal undamped acceleration during the overhaul cycle. The optimal elevation of the out-er rail has been calculated and the actual values in the investigated sections have been analyzed. The method’s economic efficiency is calculated in the form of the ratio of the difference between the costs of the overhaul cycle for the actual and optimal elevations of the outer rail. Practical im-portance: Optimization of the elevation of the outer rail will enable minimizing the intensity of the accumulation of faults and, therefore, reduce the cost of maintenance on the track. The total cost of routine track maintenance will be reduced by 5–10 %.

Role of melt flow dynamics on track surface morphology in the L-PBF additive manufacturing process

Laser powder bed fusion (L-PBF) is an additive manufacturing process used to fabricate intricate metallic parts by melting successive layers of metallic powder. However, the fabricated part's poor surface roughness limits the extent to which the process can be used. The process involves rapid melting and solidification, and the unsteady flows within the melt pool dictate the surface morphology of the solidified tracks, which governs the surface smoothness of the end product. This work reports an experimental and computational investigation on the role of melt flow dynamics on the track's surface morphology. Single tracks were experimentally built by varying laser spot radius and scanning speed, and the corresponding melt pool and track surface morphology were characterized using metallographic and 3D optical profilometry techniques. Track formation is numerically simulated using an integrated 3D Discrete Element- Computational Fluid Dynamics (DEM-CFD) model. DEM is used to determine the spatial arrangement of the particles in the powder layer. In the CFD model, a free surface (VOF) approach is employed to precisely capture the interface between the gas and the metal phase. The interaction of laser with the powder bed and substrate, the physics of melting, solidification, and evaporation, and the melt flow due to interfacial forces (surface tension and recoil pressure) are accounted. With the help of simulation results, the role of melt flow dynamics on track morphology is described. Track roughness in the experimental samples is predicted with the help of multivariate polynomial regression analysis. The experimental and numerical data of track surface roughness and melt pool characteristics show decent agreement. Based on computational and experimental results, it was found that there exists an optimum scanning speed and laser spot radius which provide the minimum track surface roughness.

Tribological and anticorrosion properties of polyvinyl butyral (PVB) coating reinforced with phenol formaldehyde resin (PF)

A series of environmental-friendly polyvinyl butyral/phenol formaldehyde resin (PVB/PF) composite coatings with various PF contents were prepared by solution blending method. The tribological and anticorrosion properties of composite coatings as well as the influence of PF content were systemically studied. The results showed that the addition of PF can significantly improve the wear resistance of the PVB coating, with the minimum wear track width being reduced from 301 μm (pure PVB coating) to 154 μm (PVB/PF composite coating) under dry friction condition. Besides, electrochemical impedance spectroscopy (EIS) results showed that the corrosion resistance of the composite coatings can also be significantly improved after immersing in 3.5 wt% NaCl aqueous solution for 30 days. The impedance modulus at low frequency (│Z│0.01Hz) of 30 wt% PF reinforced composite coating is 2.41 × 107 Ω cm2 after immersed for 30 days, which is three orders of magnitude higher than that of pure PVB coating. The good tribological and anticorrosion properties of composite coating can ascribe to the uniform and dense structure formed by PVB and PF, which has good flexibility, high mechanical strength and excellent barrier properties.

The influence of the parameters of the running systems of wheeled vehicles on the change in soil density

The movement of wheeled vehicles on soils and grounds leads to a change in their density. The research includes the influence of mass and its distribution along the axes of the wheels on the change in the density of soils and grounds. The substantiation of analytical dependencies for determining the density of compacted and flowing soils and soils from repeated impacts of wheels under various loads is given. The dependence for determining the density of the soil in the general case, including compressed and fluid components of the state of the soil and soil mass, was substantiated.
 The experimental laboratory studies were carried out on the effect of wheels on the soil and the effect of wheel load on soil compaction. The dependences were obtained to determine the compaction of soil with different physical and mechanical properties under different loading modes of the running systems. It was found that the distribution of the mass of a wheeled vehicle along the axles of the wheels affects the depth of the track and the compaction of the soil. The obtained dependences for describing the process of soil compaction are consistent with the results of experiments. It was found that with an increase in the number of axles of the running system, soil compaction decreases. The minimum track depth and soil compaction are observed when the mass of the wheeled vehicle is evenly distributed along the axes of the chassis. With an increase in the number of axles, the influence of the ratio of the pressure of the first wheel to the average pressure on soil compaction decreases due to a decrease in the differential pressure of the wheels that occurs in multi-axle wheel systems. With slight deviations from the unit of the ratio of the front wheel load to the average value of the pressure, the increase in soil density is not perceptible. As the front-to-middle load ratio increases, soil compaction increases significantly compared to an even weight distribution along the axles.

Robust-optimal integrated control design technique for a pressurized water-type nuclear power plant

A control design scheme is formulated for a pressurized water type nuclear power plant by integrating the optimal linear quadratic Gaussian (LQG) control with the robust integral sliding mode (ISM) technique. A novel robust-optimal hybrid control scheme is further proposed by integrating the LQG-ISM technique with the loop transfer recovery approach to enhance the effectiveness and robustness capability. The control architecture offers robust performance with minimum control efforts and tracks the reference set-point effectively in the presence of disturbances and parametric uncertainties. The multi-input-multi-output nuclear power plant model adopted in this work is characterized by 38 state variables. The nonlinear plant model is linearized around steady-state operating conditions to obtain a linear model for the controller design. The efficacy of the proposed controllers is demonstrated by nuclear power plant subsystem simulations. The control performance of the proposed technique is also compared with other classical control design schemes. Numerical measures are employed to quantitatively analyse and compare the performance of the different controllers that are studied in the work.

Thin Film Metallization Stacks Serve as Reliable Conductors on Ceramic-Based Substrates for Active Implants

Substrates and packages of active implantable medical devices are often fabricated from ceramics, such as alumina. Screen-printed PtAu paste is the state-of-the-art metallization for functional structures. Due to solid-state and liquid diffusion of Au during thermal exposure, solder times are limited. Otherwise, metal structures tend to delaminate. Moreover, it was shown that PtAu with solder fails after 37.4 years. We established a thin film metallization on the alumina process to overcome these disadvantages. We used sputtered platinum with an underlying adhesion layer made of tungsten–titanium to increase the adhesion strength of the alumina substrate. We avoided using gold in this work due to its high diffusion tendency. All used materials provided relatively low diffusion properties, which increases independence from joining techniques and mechanical longevity during use. Utilizing the Design of Experiment (DoE) methodology, we derived an optimal Pt thickness of 500 nm with 43 nm of WTi as an adhesion-promoting layer. After accelerated aging at 150 °C, corresponding to 125 years at body temperature (37 °C), the contact pad adhesion strength was 32.75 ± 7.08 MPa. This exceeded the safety limit of 17 MPa by far, set as a recommendation for robust screen-printing metallization processes. Soldering times of up to 120 s did not influence the adhesive strength. The new process reduced the minimum track distance to 50% of screen-printing values and is capable to be transferred into rapid prototyping techniques. It helps to make the assembly process independent of the manufacturing person in order to increase the yield of device fabrication and—most important in implantable device manufacturing—to make it more robust and thereby safer for the patient.

The Concept of a Compact Profile Agricultural Tractor Suitable for Use on Specialised Tree Crops

This study firstly examined certain methods of vineyard management typically adopted in Apulia for both table grapes and wine grapes. In the later phenological stages, guyot or spurred cordon vineyards have extremely abundant vegetation, which drastically limits the space available between the rows for the passage of a tractor, even for a narrow-track vehicle. On the other hand, vegetation in tendone vineyards is situated at approximately 1.90 m above the soil surface, so that total tractor height must be compatible with this cultivation method. Foliage canopies in these types of vineyard cultivation system were evaluated at the times of their maximum growth in order to identify the maximum possible size of a prototype tractor that would be able to pass between vineyard rows without interfering in any way with the vegetation and fruits. Using the results of field measurements, it was established that the prototype tractor must have a maximum height of 1600 mm, with a minimum front axle track of less than 1100 mm and a back axle track of less than 1000 mm. A tractor built to these specifications is now being tested in order to compare its performance with that of other tractors commonly used in Apulia in various agricultural contexts.

Microparticle Responses to Aerobic Exercise and Meal Consumption in Healthy Men.

Microparticles (MP) are shed extracellular vesicles that express the prothrombotic tissue factor (TF). Aerobic exercise may reduce MP count and TF expression. This study investigated the impact of acute running or rest followed by standardized meal consumption on MP phenotypes and TF expression. Fifteen males (age, 22.9 ± 3.3 yr; body mass, 81.9 ± 11.4 kg; V˙O2max, 54.9 ± 6.5 mL·kg·min; mean ± SD) completed 1 h of running (70% V˙O2max) or rest at 9:00 AM and consumed a standardized meal (1170 kcal, 43% CHO, 17% PRO, 40% fat) at 10:45 AM. Venous blood samples were taken at 9:00 AM, 10:00 AM, and 11:30 AM. The MP concentration, diameter, phenotypes, and TF expression were assessed using nanoparticle tracking analysis and flow cytometry. Nanoparticle tracking analysis identified no changes in MP concentration or diameter in response to time or trial. Flow cytometry revealed total MP count increased from 9:00 AM to 10:00 AM (1.62 ± 2.28 to 1.74 ± 2.61 × 10 L, P = 0.016, effect size (η) = 0.105), but was unaffected by trial. TF platelet-derived MP % reduced from 9:00 AM to 10:00 AM (44.0% ± 21.2% to 21.5% ± 9.3%, P = 0.001, η = 0.582) after exercise only (control, 36.8% ± 18.2% to 34.9% ± 11.9%; P = 0.972). TF neutrophil-derived MP percentage reduced from 9:00 AM to 11:30 AM (42.3% ± 17.2% to 25.1% ± 14.9%; P = 0.048, η = 0.801) in the exercise trial only (control, 28.5% ± 15.7% to 32.2% ± 9.6%; P = 0.508). Running induced a significant reduction in %TF platelet and neutrophil MP, suggesting a transient reduction in cardiovascular risk via reduced TF-stimulated thrombosis. This requires further investigation over longer periods in cardiovascular disease populations.

Direct Energy Deposition - Laser Additive Manufacturing of Titanium-Molybdenum alloy: Parametric studies, microstructure and mechanical properties

In this novel research, the Direct Energy Deposition - Laser Additive Manufacturing (DED-LAM) process is used for deposition of β-type Titanium Molybdenum (Ti-15Mo) biomedical alloy. A major challenge in the successful deposition of an alloy powder on the substrate by the DED-LAM process is the formation of a strong metallurgical bond with minimum track dilution. Targeting a crack-free and dense multi-layer deposition, a detailed investigation of the effect of three key process parameters on the track geometry characteristics is conducted. The response surface methodology (RSM) experimental design technique and ANOVA based quadratic regression modeling are employed to relate the process parameters with track geometric characteristics. The statistical analysis results show that minimum track dilution is achieved at maximum laser power and minimum scan speed and powder feed rate. Further, microstructural characterization is carried out to analyse the porosity, elemental composition and phase constituents. Microhardness of 385 ± 8 HV and elastic modulus of 73 ± 1.5 GPa are achieved for the Ti-15Mo deposits at the optimum parameter settings. This study establishes a methodology towards successful deployment of the DED-LAM process for potential fabrication of Ti-15Mo alloy biomedical implants.

SENSITIVITY OF TROPICAL CYCLONE TRACK TO ASSESSMENT OF SEVERE STORM SURGE EVENT AT TOKYO BAY

In total 82 tropical cyclones data was used to determine scenarios of translation speed, minimum central pressure and track for risk assessment of storm surge at Tokyo Bay. The numerical simulation of waves and flows was conducted by solving non-linear long wave equations. The maximum surge height shows that the typhoon passing through along northeast directional track is dangerous for Tokyo Bay. This trend confirms the previous risk assessment was reasonable. However, it has been shown that the typhoon passing through along north directional track is also dangerous although the frequency is low. Especially, it is interesting that the typhoon passing through along northwest directional track causes distinctive resurgence and harbor oscillation.

Fabrication and characterization of nano-Y2O3 and Al2O3 dispersed W-Ni alloys by mechanical alloying and pressureless conventional sintering

Nano Y2O3 and Al2O3 dispersed W-Ni alloys with nominal composition of W89Ni10 (Y2O3)1 (alloy A), W89Ni10 (Al2O3)1 (alloy B) were mechanically alloyed for 10 h followed by compaction at 0.5 GPa pressure with 5 min of dwell time and conventional sintering at 1400°C with 2 h soaking time in Ar atmosphere with Ar flow rate of 100 ml/min. The microstructure of milled and sintered alloy was investigated using X-ray Diffraction (XRD), Scanning electron Microscopy (SEM), Energy dispersive spectroscopy (EDS) and Elemental mapping. Minimum crystallite size of 31.9 nm and maximum lattice strain, dislocation density of 0.23%, 9.12(1016/m2) respectively was found in alloy A at 10 h of milling. Uneven and coarse particles at 0 h of milling converted to elongated flake shape at 10 h of milling. Bimodal (fine and coarse) particle size distribution is revealed in both the alloys and minimum particle size of 0.69 μm is achieved in 10 h milled alloy A. Evidences of formation of intermetallic phases like Y2WO6, Y6WO12 and Y10W2O21 in sintered alloy A and Al2(WO4)3, NiAl10O16, NiAl2O4 and AlWO4 in sintered alloy B were revealed by XRD pattern and SEM micrograph. Minimum grain size of 1.50 μm was recorded in sintered alloy A. Both faceted and spherical W matrix is evident in both the alloys which suggests occurrence of both solid phase and liquid phase sintering. Maximum % relative sintered density and hardness of 85.29% and 5.13 GPa respectively was found in alloy A. Wear study at 20N force at 25 rpm for 15 min on ball on plate wear tester revealed that minimum wear depth (48.99 μm) and wear track width (272 μm) was found for alloy A as compared to alloy B.

Impacts of Ocean Cooling and Reduced Wind Drag on Hurricane Katrina (2005) Based on Numerical Simulations

Abstract Tropical cyclone (TC) intensity is strongly influenced by surface fluxes of momentum and moist enthalpy (typically parameterized in terms of “exchange coefficients” Cd and Ck, respectively). The behavior of Cd and Ck remains quite uncertain especially in high wind conditions over the ocean; moreover, moist enthalpy flux is extremely sensitive to sea surface temperature (SST). This study focuses on numerical simulations of Hurricane Katrina (2005) from an atmosphere–ocean coupled modeling system to examine the combined impacts of air–sea flux parameterizations and ocean cooling on TC evolution. Three momentum flux options—which make Cd increase, level off, or decrease at hurricane-force wind speeds—with five different Ck curves are tested. Maximum 10-m wind speed Vmax is highly sensitive to Cd, with weaker sensitivities for minimum sea level pressure Pmin and track. Atmosphere-only runs that held SST fixed yielded TCs with Pmin substantially deeper than observations. Introducing ocean coupling weakens TC intensity with much more realistic Pmin. The coupled run with the flux parameterization that decreases Cd at high wind speeds yields a simulated TC intensity most consistent with observations. This Cd parameterization produces TCs with the highest Vmax. Increasing Ck generally increases surface heat fluxes and thus TC intensity. For coupled runs using the default Ck parameterization, the simulated SST fields are similar (regardless of Cd parameterization) and agree well with satellite observations. The mesoscale oceanic eddies, which are well resolved in the ocean model, contribute to the magnitude of TC-induced SST cooling and greatly influence TC intensity.