Dimension Ratio Research Articles

Modeling immiscible fluid flow in fractal pore medium by multiphase lattice Boltzmann flux solver

In this paper, the multiphase lattice Boltzmann flux solver (MLBFS), where the phase field model and the apparent liquid permeability model are built-in, is developed to simulate incompressible multiphase flows in fractal pore structure at the representative elementary volume scale. MLBFS takes advantage of the traditional Navier–Stokes solver (e.g., geometric flexibility and direct handling of complex boundary conditions) and lattice Boltzmann method (e.g., intrinsically kinetic nature, simplicity, and parallelism). It is easily applied to simulate multiphase flows transport in the porous medium with large density ratios and high Reynolds numbers. This study focuses on the fluid flow in fractal pore structures and provides an in-depth discussion of the effects of non-Newtonian index, fractal parameters, and density ratios on multiphase flow. The proposed model is validated with benchmark problems to test the applicability and reliability of the MLBFS in describing fluid flow in fractal pore structures with large density ratios and viscosity ratios. Simulation results show that the fractal parameters (i.e., fractal dimension, tortuous fractal dimension, porosity, and capillary radius ratio) can accurately characterize fractal pore structure and significantly affect the apparent liquid permeability. In addition, the flow rate increases with the fractal dimension and decreases with the tortuous fractal dimension, while both flow rate and apparent liquid permeability decrease as the capillary radius ratio. It is also noteworthy that the effect of nonlinear drag forces cannot be neglected for shear-thickened flows.

Statistical analysis of residual stresses in austenitic pipe girth welds

Residual stresses created from welding have a direct influence on fracture mechanisms of cracks and flaws in and around welded regions. Excessive residual stress can lead to unexpected failures and an important property in fitness-for-service calculations. In this work, an experimental database of the residual stress of low heat input austenitic girth welds is analysed for statistical correlation. The combined measurement profiles indicate normality throughout the weld thickness. Two-sample tests of grouped datasets were additionally carried out to examine potential relationships within the data. Presented measurements were characterised by location from weld centre, and similarly, by pipe aspect ratio. Results indicate a moderate influence of dimension ratio on residual stress in piping components suggesting potential for additional consideration in fitness-for-service procedures.

Buckling Behavior of Loosely Fitted Formed-In-Place Pipe Liner in Circular Host Pipe under External Pressure

The formed-in-place pipe (FIPP) is a trenchless technology used for pipeline rehabilitation. It is a folded PVC pipe that expands through thermoforming to fit tightly inside the host pipe. However, the deficiencies during the construction of FIPP liners such as insufficient inflation, pipe misalignment and initial deformation will lead to elliptical deformation of the FIPP liner, which affects the load-bearing performance of the liner and makes it susceptible to buckling failure. In this paper, the buckling behavior of loosely fitted FIPP liners under uniform external pressure was investigated by the external pressure resistance test and finite element model. The pre- and post-buckling equilibrium paths verified the finite element model. The results indicated that the value of the dimension ratio will significantly reduce the critical buckling pressure. With the increasing value of liner major axis ratio to host pipe, the reduction effect on the critical buckling pressure caused by the increase in the ovality will diminish. Different values of liner major axis ratio to host pipe and ovality changed the range of the detached portion, which affected the critical buckling pressure. The parametric studies modified the design model from ASTM F1216, which was established to predict the critical buckling pressure of a loosely fitted FIPP liner and reduced the average difference rate from 23.43% to 5.52%.

Morphological variations in blood cockle Tegillarca granosa (L, 1758) populations collected from the south-east and south-west coasts of Bangladesh

Morphology helps in studying the external features of an individual, including the size, shape, structure of the animals and in determining the evolutionary relationships among organisms. Current study was undertaken to investigate the morphological variations between the two populations of blood cockle, Tegillarca granosa collected from the south-east (west coast of Maheshkhali Island, Cox’s Bazar; S1) and south-west (Jamuna River Estuary near Ishawrypur, Shemnagar, Shatkhira; S2) coasts of Bangladesh. Samples were drawn from the intertidal region during low-tide by hand-picking with the aid of local people in March 2020 from both sites. Fifteen primary parameters, and 27 secondary parameters obtained from the ratios of different primary parameters were studied to compare the values between the two populations. Out of 15 primary morphological parameters, there was no significant difference (p>0.05) between the populations. Among the 27 secondary morphological parameters, only 4 parameters were significantly different (p<0.05) between the two populations. The statistically different parameters were shell length (SL)/wet tissue weight (TWW), shell height (SH)/wet tissue weight (TWW), shell thickness (ST)/wet tissue weight (TWW) and condition index (CI). The ratios of shell dimensions and wet tissue weight were significantly higher (p<0.05) in S2 when compared with S1 indicated that S1 population could be more economically viable due to their relatively higher edible meat content. The CIs were significantly higher (p<0.05) in S1 population than the CIs of S2 population. The values of CIs reflected that S1 population had better health condition than S2 population. The ratios of different shell measurements did not vary significantly implied that both populations were homogenous in size, shape and structure. Morphological analyses of different populations of T. granosa revealed that habitat could play a vital role in morphological variations.

The Relationship between 3 Dimensional Measurement Ratios of Solid Thyroid Nodules and Thyroid Papillary Carsinoma: A Retrospective Cohort Study

The Relationship between 3 Dimensional Measurement Ratios of Solid Thyroid Nodules and Thyroid Papillary Carsinoma: A Retrospective Cohort Study

Ring at Clava as the allusion to the dimensional features of the pyramid of Cheops

The proposed study was devoted to the analysis of the scheme of dimensional and geometric ratios of the circle of stones in Clava and is a kind of continuation of the topic raised in our previous publication, analyzing such megalithic monument as "calendar circle" in Nabta Playa. Like the previous study, this one relies on the application of some prime numbers, most commonly 37, but also others related to the "Cupola Algorithm's" sequence of numbers. The article shows that the creators of the circle in Clava were well acquainted with the methods of precise geometric constructions, and with the ancient Egyptian system of linear measures, in addition, the dimensions of this circle with a high degree of probability is the allusion at the dimensional and geometric features of the Cheops pyramid.

Finding a New Home: Rerouting of Ferry Ships from Merak–Bakauheni to East Indonesian Trajectories

As an archipelagic country, Indonesia needs ferry transportation to connect and support the economic activities between areas bounded by the sea. The famous crossing route is the Merak–Bakauheni one, which connects the Java and Sumatra economic corridors. Many ships operate on this route, but limited port facilities significantly affect the efficiencies of the services provided, hence, they have to be moved. Therefore, this research analyzed the suitability of ships to operate on the eastern crossing. The analysis method used the financial aspect (revenue) feasibility, the suitability of the port infrastructure, and the oceanographic conditions. The financial analysis used the ships’ operating cost method to determine the crossing passage rates based on their specifications. It simulated the ships with various load factors to identify potential gains or losses. Furthermore, the infrastructure suitability analysis used the under keel clearance and comparative methods to compare the suitability of the ship dimensions and tonnage with the port infrastructure capacity. The oceanographic analysis used the Weibull method to simulate the redefinition of the distribution of significant wave heights, which was compared with the ratio of the ship dimensions and wave slope to determine its heel angle using the IMO Weather Criterion method (IS Code 2008). The results showed that the relocation of ships from the Merak–Bakauheni route directly to Eastern Indonesia through the existing crossing routes is feasible from the aspect of shipping safety, but it is not feasible financially or in terms of infrastructure. The Benoa–Labuan Bajo route is a potential new route recommendation, with regulatory support for the operation of ships in the form of tariffs and operational costs, and it permits the use of subsidized fuel. On the other hand, ship owners must consider modifying the ramp door to suit the port wharf structure.

DEVELOPMENT OF THE PROCESS OF STAMPING BY ROLLING OF TUBULAR PREPARATIONS USING INDUCTION HEATING

Methods of pressure treatment of metals based on the action of technological load in the conditions of a localized plastic cell. The main purpose of such methods is that the change in shape at any time is performed only on a fraction of the volume of the workpiece and when moving the deformation center covers the entire volume. These are well-studied and widely used in the production of free forging, rotary forging, rolling, etc. A relatively new method of MP - stamping by rolling, is characterized by a number of positive effects: - reduction of deformation force in comparison with traditional methods in 5-30 times; - the possibility of processing metal in the cold state with the same technological effort as in hot processing; - the equipment corresponds to a high level of labor safety; - reducing the size, weight and cost of equipment; - the possibility of implementing various technological operations. Modern mechanical engineering, instrument making and other metalworking industries widely use and manufacture parts with a large ratio of cross-sectional dimensions, the production of which by existing methods of metal forming is either inefficient or impossible. The most technological are the processes of SHO, in which the workpiece has a tubular or annular shape. Such blanks are well amenable to induction heating, which while providing a high frequency electromagnetic field allows them to be heated quickly and efficiently. This can heat a limited amount of workpiece material. Thus, the use of induction heating in the processes of SHO significantly expands their technological capabilities, which determines the relevance of the chosen topic. The main advantages of induction heating include: transmission of electrical energy does not require contact devices, is carried out directly into the workpiece, which increases the heating rate; due to the possibility of controlling the frequency of the current, the maximum power is released in the limited thickness of the surface layer of the product, which is especially effective when heating the pipe blanks; induction heating can increase productivity and improve working conditions.

Optimization of a combined tanker/platform type vessel based on simulation modeling

The choice of the height of the side of a cargo vessel, as a rule, is carried out on the basis of solving the equation of cargo capacity, while the remaining requirements for its size act as restrictions. However, if the ratios of the main dimensions and the requirements for the minimum freeboard height are somewhat conditional, then ensuring seaworthiness, which, in addition to capacity, when choosing the side height, should include unsinkability, requires high-quality accounting. The article presents a mathematical model for assigning the freeboard height, taking into account the requirements of the Rules of the Russian Classification Society for checking the landing and stability during flooding of one or several adjacent regulated compartments; an analysis of the effect on the height of the side of flooding of various compartments of an oil tanker of mixed (river-sea) navigation is carried out and an approximate formula for calculating it at the initial stages of design is proposed.

Architected Low-Tortuosity Electrodes with Tunable Porosity from Nonequilibrium Soft-Matter Processing.

Mass transport is performance-defining across energy storage devices, often causing limitations at high current rates. To optimize and balance the device-scale energy and power density for a given energy storage demand, tailored electrode architectures with precisely controllable phase dimensions are needed in combination with low-tortuosity channels that maximize the geometric component of diffusion and species flux. A material-agnostic nonequilibrium soft-matter process is reported to fabricate free-standing inorganic composite electrodes with adjustable thicknesses of 100s ofµm, featuring straight and accessible channels ranging in diameter from 5-30µm, coupled with tunable material-to-pore ratios. Such architected anode and cathode electrodes exhibit electrochemical and architectural stability over extended cycling in a full-cell battery. Further, mass-transport constraints appear at high current densities, and the lithiation step is identified as rate-performance limiting, a result of insufficient lithium-ion supply and concentration polarization. The results demonstrate the need for and feasibility of tailored electrode architectures where dimensional ratios between low-tortuosity channels, the charge-storing matrix, and electrode thickness are tunable to meet coupled power and energy-storage requirements.

Submarine Manoeuvrability Design: Traditional Cross-Plane vs. x-Plane Configurations in Intact and Degraded Conditions

Submarines’ manoeuvrability both in intact and degraded operating conditions is the main design concern starting at the very early stages of design. This increased complexity of the design process compared to a surface vehicle can only be handled by using dynamics numerical simulations on both the vertical and horizontal manoeuvring planes. To this aim, a 6-DoF method is presented, validated, and applied to study the manoeuvring characteristics of several vessels. The analysis has been conducted considering two standpoints, i.e., to verify the design handling capabilities of the vehicles at low and high speeds and to study the off-design residual abilities in the eventual case of emergency operations with jammed/lost-control surfaces. The influence of different design features, such as, e.g., the stern plane “+” and “x” configurations, fairway size and positioning, hull dimensional ratios and restoring capabilities have been analysed in terms of impact on turning ability, course and depth changing abilities, and vertical/horizontal course stability, including the vertical damping ratio and critical velocity.

A combined heat transfer enhancement technique for shell-and-tube latent heat thermal energy storage

The most significant drawback of latent heat thermal energy storage systems is the low thermal conductivity of phase-change materials (PCMs), which significantly slows thermal energy transfer rates. The objective of this research is to introduce the helical-coiled shell-and-tube unit with spiral fins as an energy and exergy efficient, and melting and solidification time reduction design for the PCM-based TES applications. The new design is a combination of the advantages of horizontal and vertical systems by offering helical-coiled shell-and-tube, proper shell-to-tube dimension ratio and the addition of spiral fins in a single configuration. Numerical experiments are conducted to compare PCM melting and solidification times, energy and exergy efficiency during charging, discharging for nine thermal energy storage designs. The results show that the proposed latent heat thermal energy storage unit, significantly reduces PCM melting and solidification times when compared to vertical (60% reduction in melting time; 26% reduction in solidification time) and horizontal (44% reduction in melting time; 21% reduction in solidification time) shell geometries, and achieves the highest overall exergy efficiency, the lowest solidification time, and low melting time. All units with conical shell geometries significantly reduce PCM melting time, while greatly extending total PCM solidification time.

Prognostic value of left atrial stiffness estimated using echocardiography in dogs with myxomatous mitral valve disease

IntroductionNo studies have investigated the prognostic value of left atrial stiffness (LASt) estimated using echocardiography in dogs with myxomatous mitral valve disease (MMVD). AnimalsSeventy-two dogs had MMVD and 46 dogs were healthy dogs. Materials and MethodsClinical retrospective cohort study. The survival information of MMVD dogs that underwent echocardiographic examination was obtained. The peak velocities of early diastolic transmitral flow (E) and mitral annular motion as determined by pulsed wave Doppler (E′) were determined. The left atrial reservoir strain (εS) was determined by two-dimensional speckle tracking echocardiography of the left atrium. The LASt was estimated by the formula: E/E′/εS. The 95% prediction interval of LASt was computed from the data of the healthy dogs. ResultsSeventeen dogs having MMVD died of cardiac-related causes with 55 MMVD dogs censored. The MMVD dogs with LASt > its 95% upper prediction limit (LASt > 0.56; n = 26; median survival time, 484 days; 95% confidence interval, 283 days-indeterminable) had shorter survival times (P<0.001) than those with LASt ≤ its 95% upper prediction limit (LASt ≤ 0.56; n = 46; median survival time, >1112 days; 95% confidence interval, indeterminable). Multivariable Cox's proportional hazard analysis demonstrated that the ratio of the left atrial dimension to the aortic annulus dimension and LASt were independent predictors of cardiac-related death among conventional echocardiographic indices, εS and LASt in MMVD dogs. ConclusionsIn dogs with MMVD, increased LASt estimated using echocardiography is an independent predictor of cardiac-related death, and LASt can be more useful for prognostication than εS.

Analysis of the dedusting process in a rectangular chamber filter

Abstract Purifying air from dust is a very important, current topic. There are many methods to minimize the amount of dust, one of them being chamber filters. This paper presents the research results of a newly designed rectangular chamber filter. The efficiency of the dedusting process is influenced by contamination properties, but also by the construction of the apparatus, inlet, and outlet location, the ratio of certain dimensions, and the gas flow rate. The airflow containing solid particles is a multi-phase, difficult-to-describe issue, therefore an attempt to determine the trajectory of particle movement in the apparatus was carried out using the PIV method. A decrease in the dedusting efficiency was observed with the increase of the gas flow rate, as well as for smaller diameters of the solid particles. The obtained values of the efficiency of the apparatus are comparable with the values obtained for the constructions discussed in other papers.

FSS embedded high gain ‘N’ shaped miniaturized broadband antenna

This research work represents a broadband (3.3 GHz − 17.85 GHz) high gain miniaturized (16 mm × 24 mm × 1.6 mm) microstrip patch antenna. Initially multiband property is achieved through ‘N’ shaped radiating patch surface and ‘I’ shaped ground plane surface. Finally broadband property is attained through better impedance matching by modifying feeding structure with a single step matching staircase structure. The presented antenna shows large −10 dB impedance bandwidth of 14.55 GHz with a percentage bandwidth of 138 %, Bandwidth Dimension Ratio (BDR) of 2970 and a peak gain of 4.45 dBi at 9.5 GHz. By embedding FSS (Frequency Selective Surface) structure having FSS unit cell dimension of 13 mm × 13 mm × 1.6 mm with the antenna at suitable distance, antenna gain has been elevated successfully across the entire operating frequency range (3.25 GHz–17.8 GHz). FSS coupled antenna exhibits highest gain improvement of 7.5 dBi at 3.5 GHz and peak gain of 9.1 dBi at 9.3 GHz. The FSS integrated antenna structure operates with elevated gain (peak gain of 9.1 dBi at 9.3 GHz) across the entire operating frequency range (3.25 GHz–17.8 GHz). All inclusive volume of the presented FSS coupled antenna is 52 mm × 52 mm × 21.2 mm, which can be successfully utilized in high gain broadband wireless applications. The antenna patch area miniaturization is calculated as 65 % with respect to lowest frequency of operation. The proposed FSS and antenna are developed and simulated by utilizing CST Studio Suite Software and equivalent circuit of the presented antenna is simulated utilizing ADS software. Both FSS and antenna are fabricated using inexpensive FR 4 substrate (1.6 mm thick, relative dielectric constant of 4.4 and loss tangent of 0.02) and Standard Microwave Test Bench is used to validate the antenna and composite antenna structure simulation results.

Communication A Novel Systematic Design of High-Aperture-Efficiency 2D Beam-Scanning Liquid-Crystal Embedded Reflectarray Antenna for 6G FR3 and Radar Applications

This communication presents a novel systematic design of a high-aperture-efficiency and 2-D beam-scanning nematic liquid-crystal (LC)-based reflectarray (LCRA) that operates in the sixth-generation (6G) midband (7–24 GHz). Despite a 260° phase range, the maximum aperture efficiency is 35.8% at an aperture dimension (F/D) ratio of 0.58, the highest aperture efficiency at the lowest F/D ratio among LCRAs designed to operate on the mmWave band. The proposed LC-based reflectarray unit cell (LC-RUC) has significantly low reflection loss compared to other LC-RUCs. Also, the bias topology of the proposed LC-RUC makes the LCRA capable of 2-D beam scanning. The beam-scanning range of the proposed LCRA is ±50° on the xoz plane and 0°–65° in the yoz plane at 9.55 GHz. A <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 \times 2 $ </tex-math></inline-formula> patch array antenna is designed as the feed antenna to achieve a small F/D ratio system and ease of optimization. When designing the feed antenna, the number of elements or the element spacing is considered to achieve high feed efficiency. In addition, the fabricated planar feed antenna can be easily integrated with a 3-D printed jig in which the focal length can be adjusted for optimization. The lowest side lobe level (SLL) of the proposed LCRA is −15.5 dB.

Observable tests for the light-sail scenario of interstellar objects

Context.Enigmatic dynamical and spectral properties of the first interstellar object (ISO), 1I/2017 U1 (Oumuamua), led to many hypotheses, including a suggestion that it may be an “artificial” spacecraft with a thin radiation-pressure-driven light sail. Since similar discoveries by forthcoming instruments, such as theVera C. Rubintelescope and the Chinese Space Station Telescope (CSST), are anticipated, a critical identification of key observable tests is warranted for the quantitative distinctions between various scenarios.Aims.We scrutinize the light-sail scenario by making comparisons between physical models and observational constraints. These analyses can be generalized for future surveys of ‘Oumuamua-like objects.Methods.The light sail goes through a drift in interstellar space due to the magnetic field and gas atoms, which poses challenges to the navigation system. When the light sail enters the inner Solar System, the sideways radiation pressure leads to a considerable non-radial displacement. The immensely high dimensional ratio and the tumbling motion could cause a light curve with an extremely large amplitude and could even make the light sail invisible from time to time. These observational features allow us to examine the light-sail scenario of interstellar objects.Results.The drift of the freely rotating light sail in the interstellar medium is ~100 au even if the travel distance is only 1 pc. The probability of the expected brightness modulation of the light sail matching with ‘Oumuamua’s observed variation amplitude (~2.5–3) is &lt;1.5%. In addition, the probability of the tumbling light sail being visible (brighter thanV= 27) in all 55 observations spread over two months after discovery is 0.4%. Radiation pressure could cause a larger displacement normal to the orbital plane for a light sail than that for ‘Oumuamua. Also, the ratio of antisolar to sideways acceleration of ‘Oumuamua deviates from that of the light sail by ~1.5σ.Conclusions.We suggest that ‘Oumuamua is unlikely to be a light sail. The dynamics of an intruding light sail, if it exists, has distinct observational signatures, which can be quantitatively identified and analyzed with our methods in future surveys.

Optimization of cross-section dimensions of structural members made of cold-formed profiles using compromise search

The object of this study is a structural member made from a C-shaped cold-formed profile, investigated to search for optimal cross-sectional dimensions. The parametric optimization task is stated as the problem to find the optimal cross-sectional dimensions of the structural member under axial compression conditions, taking into account its post-buckling behavior (local buckling of the web and flanges, as well as a distortional buckling of the cross-section) and structural requirements. In this case, the material consumption and mechanical characteristics of steel, as well as the design lengths of the structural member, were considered constant and predefined. The considered criterion of optimality was the maximization of the load-carrying capacity of the structural member for the overall buckling under the axial compression. The stated optimization problem is solved using the method of exhaustive search while applying the developed software. Additionally, for fixed steel consumption, compromise solutions were searched that do not depend on the thickness of the profile and the design lengths of the structural member. The resulting cold-formed C-shaped profiles with optimal cross-sectional dimensions are characterized by a higher load-carrying capacity for the overall buckling under axial compression (to 24.45 % and 22.19 %) at the same steel consumption compared to the profiles offered by the manufacturer. Analysis of the reported results made it possible to devise recommendations for optimal ratios of dimensions and geometric characteristics of the structural members made from C-shaped profiles operating under axial compression. The ratios could be used both at the stage of selection of cross-sections of structural members from cold-formed profiles, and in the development of effective assortments of cold-formed profiles

Effect of vulcanization on deformation behavior of rubber seals: Thermal–mechanical–chemical coupling model, numerical studies, and experimental validation

Vulcanization molding has a significant impact on dimensional changes of rubber seals. Numerical analysis of this process can improve dimensional accuracy of molded sealing products. In this study, a stress–strain relationship model that considers thermal expansion, cold contraction, and shrinkage caused by a crosslinking reaction under the constraint of a mold boundary was established, a transient analysis method for thermal–mechanical–chemical coupling of the process from rubber seal vulcanization to mold opening was developed, and dimensional changes of the rubber seal in the mold and after cooling were predicted. Results calculated by the model were verified by the production of typical seals. The influences of vulcanization process parameters on changes in molded seal size were numerically analyzed. The numerical results showed that the dimensional shrinkage ratio increased nonlinearly from 3.2 % to 3.8 % when the vulcanization temperature increased from 165 to 185 °C, i.e., an increase of 0.206 % for every 1 % increase in shrinkage caused by the vulcanization reaction. These research results can be utilized in the design of vulcanization molds for high-precision rubber seals.

Real-Time Inspection of Rod Straightness and Appearance by Non-Telecentric Camera Array

In this paper, we propose a measurement system that employs a camera array based on a non-telecentric optical system and an accompanying measurement algorithm to measure the straightness, length, diameter, and appearance of a rod. Measurements using telecentric optical systems, which employ orthogonal projection to preserve the dimensional ratios regardless of distance, are common in image-based inspection of the dimensional or geometrical tolerances of industrial products. However, some cases depend on the size of the target or inspection item, wherein it is difficult to configure a measurement system using telecentric optical systems. As an example, this study considers the measurement of straightness of a long rod and shows that it is possible to achieve high measurement accuracy using non-telecentric optical systems by introducing methods to calibrate miniscule errors and distortions that remain uncorrected in conventional image calibration methods. We also show that the same measurement allows for the measurement of other inspection items and evaluation of their respective measurement accuracies, thereby proving that a flexible image-based inspection process can be constructed using the proposed system and method.