Scale Ratio Research Articles

Experimental and theoretical study on the characteristics of the spill plume in a compartment fire with high-low opposing openings

This paper presents the characteristics of the spill plume in a compartment fire with high-low opposing openings. Three sizes of doors (low openings), six sizes of windows (high openings), and three heat release rates were adopted. Mass flow rates through the openings were calculated with new length scales considering the effect of bidirectional airflow at the door, and then the expression of the neutral plane height was derived. The calculated results had good agreement with the experimental results. To reveal the effect of the opening sizes on the energy proportion, the heat fluxes from the openings were calculated based on the new length scales, and the heat lost through compartment boundaries was also obtained. It was found the size variation of any opening would affect the proportion of each part of the energy and the ratio of heat flow through openings can be represented by the 5/2 power of the ratio of the new length scales. The fire spill plume thickness is related to the horizontal velocity of the plume ejected from the window, and one linear relationship was established. Moreover, the heat flux along the façade and the temperature distribution of the fire spill plume outside the window were given with the new length scale.

Centimeter-Scale PdS2 Ultrathin Films with High Mobility and Broadband Photoresponse.

2D materials with mixed crystal phase will lead to the nonuniformity of performance and go against the practical application. Therefore, it is of great significance to develop a valid method to synthesize 2D materials with typical stoichiometry. Here, 2D palladium sulfides with centimeter scale and uniform stoichiometric ratio are synthesized via controlling the sulfurization temperature of palladium thin films. The relationship between sulfurization temperature and products is investigated in depth. Besides, the high-quality 2D PdS2 films are synthesized via sulfurization at the temperature of 450-550°C, which would be compatible with back-end-of-line processes in semiconductor industry with considering of process temperature. The PdS2 films show an n-type semiconducting behavior with high mobility of 10.4 cm2 V-1 s-1 . The PdS2 photodetector presents a broadband photoresponse from 450 to 1550nm. These findings provide a reliable way to synthesizing high-quality and large-area 2D materials with uniform crystal phase. The result suggests that 2D PdS2 has significant potential in future nanoelectronics and optoelectronic applications.

Normalized Weighting Schemes for Image Interpolation Algorithms

Image interpolation algorithms pervade many modern image processing and analysis applications. However, when their weighting schemes inefficiently generate very unrealistic estimates, they may negatively affect the performance of the end-user applications. Therefore, in this work, the author introduced four weighting schemes based on some geometric shapes for digital image interpolation operations. Moreover, the quantity used to express the extent of each shape’s weight was the normalized area, especially when the sums of areas exceeded a unit square size. The introduced four weighting schemes are based on the minimum side-based diameter (MD) of a regular tetragon, hypotenuse-based radius (HR), the virtual pixel length-based height for the area of the triangle (AT), and the virtual pixel length for hypotenuse-based radius for the area of the circle (AC). At the smaller scaling ratio, the image interpolation algorithm based on the HR scheme scored the highest at 66.6% among non-traditional image interpolation algorithms presented. However, at the higher scaling ratio, the AC scheme-based image interpolation algorithm scored the highest at 66.6% among non-traditional algorithms presented, and, here, its image interpolation quality was generally superior or comparable to the quality of images interpolated by both non-traditional and traditional algorithms.

Stability of the cascading gauge theory de Sitter DFPs

We study stability of the Dynamical Fixed Points (DFPs) of the cascading gauge theory at strong coupling in de Sitter space-time. We compute the spectra of the perturbative fluctuations and identify stable/unstable DFPs, characterized by the ratio of the strong coupling scale Λ of the gauge theory and the Hubble constant H of the background space-time. We discover a new phenomenon in the spectrum of gravitational fluctuations of a non-conformal holographic model: distinct branches of the fluctuations for H ≫ Λ coalesce for sufficiently low frac{H}{Lambda} , leading to the removal of some excited modes from the spectrum. We establish that, at least in a dual supergravity approximation, the cascading gauge theory does not have a stable DFP for some H ~ Λ. Initial states of the theory for H ≫ Λ evolve to a stable DFP with unbroken chiral symmetry; while for H ≪ Λ the states evolve to a de Sitter vacuum with spontaneously broken chiral symmetry.

Aerodynamic impacts of high-speed trains on city-oriented noise barriers: A moving model experiment

Two types of city-oriented noise barriers, i.e., fully-enclosed noise barrier and bilateral inverted l-shaped semi-enclosed noise barrier, have been gradually adopted in city centres along high-speed railways to reduce noise pollution. The aerodynamic impacts of high-speed trains present a threat to the long-term durability of the city-oriented noise barriers. To promote the usage and increase the sustainability of city-oriented noise barriers, a moving-model experiment system with city-oriented noise barriers and HST with a scale ratio of 1:16.8 is established. The train type is CRH380A and the train speed is up to 350 km/h. A systematic comparative study on the aerodynamic performance of the two types of city-oriented noise barriers is conducted. The similarities and differences of transient pressure time–histories, spatial distribution of pressure peaks and spectral characteristics of aerodynamic pressure acting on the two types of noise barriers are compared and discussed. Moreover, the influence of train speed on the characteristics of the train-induced aerodynamic pressure is also investigated. The results show that the pressure fluctuation of the two types of noise barriers is caused by different reasons. Compared with the fully-enclosed noise barrier, the transient pressure of the semi-enclosed noise barrier is more sensitive to train speeds. The research results may provide a reference for the engineering design of city-oriented noise barriers on high-speed railways.

Numerical simulation and experimental study of gas diffusion in a ship engine room

Research on the engine room's natural gas leakage and diffusion has great significance for the LNG Powered ships' design, the fire risk assessment and explosion. In this paper, a model experiment system with a scale ratio of 1:10 was established. Helium gas was used instead of natural gas to study the evolution law of light gas concentration distribution in the model engine room over time. The CFD model of light gas diffusion in the indoor thermal environment is verified by experimental data and used to simulate the natural gas diffusion behavior in a full-size ship's engine room. The influence of leakage amount, cabin temperature, ventilation conditions, leakage location and other factors on the distribution of natural gas concentration was analyzed. The results show that the established CFD model has good predictive power for the diffusion behavior of light gas in the ship's engine room, and the numerical simulation results of the trend of leakage gas concentration with time are consistent with the experiment, and the maximum error is not more than 20%. The amount of leakage has a great influence on the concentration near the leakage location. The larger the initial volume flow and the higher the temperature of the leakage, the larger the dangerous area in the ship's engine room. Increasing ventilation flow is an effective way to reduce the diffusion area and control the concentration of natural gas in the engine room. When the ventilation flow is doubled, the diffusion area of natural gas reduces to 1/3. The leaked natural gas will gather at the location nearing the obstacles which block the jet flow and the upper layer of the engine room. The research results provide a basis for accurately predicting the spatial and temporal distribution model and method of gas diffusion concentration in the engine room environment.

Combination of Riprap and Submerged Vane as an Abutment Scour Countermeasure

Scour is one of the main causes of hydraulic structural failures. The present experimental study examines the use of riprap, submerged vanes, and a combination of these for scour reduction around vertical walls and spill-through abutments under clear-water conditions. Specifically, the influence of placing riprap stones with different apron shapes (geometry) and/or a group of submerged vanes of constant height and length on abutment scour was examined. The main aim is to propose the optimum apron geometry and placement of submerged vanes to (1) reduce edge failure at vertical walls and spill-through abutments; and (2) prevent shear failure at the spill-through abutment (no shear failure is observed around the vertical wall abutment). The results show that using ripraps for scour protection is more effective than submerged vanes. However, the highest reduction in scour depth was achieved when a combination of riprap and submerged vanes was used together. This arrangement can reduce the maximum clear-water scour depth by up to 54% and 39% with vertical walls and spill-through abutments, respectively. Furthermore, selecting appropriate apron scale ratios reduces the required riprap volume by up to 46% and 31% for the vertical wall and spill-through abutment, respectively. In addition, the installation of vanes increased the riprap stability and reduced edge failure in both abutments tested. Finally, using riprap aprons with proper scales ratios at the downstream side of the spill-through abutment also prevents shear failure in this zone.

Variation characteristics analysis of sandstone strength parameters in discrete element method by using internal scale ratio

Variation characteristics analysis of sandstone strength parameters in discrete element method by using internal scale ratio

Theoretical analysis and experimental study on physical explosion of stratospheric airship envelope

The shock wave released from physical explosion of a pressurized stratospheric airship can produce serious damage to the environment. Shock wave overpressure can measure the degree of damage that an explosion can cause to such things as buildings and the human body. To obtain the overpressure from an airship envelope explosion, explosion energy must first be conducted. Explosion energy is derived based on Brode’s equation, Brown’s equation, and Crowl’s equation. An equivalent TNT computational model is then applied to calculate the overpressure of the explosion energy. In order to verify the accuracy of the computational model, a ground test must be conducted. The experimental result shows that a computational model based on Crowl’s equation is more accurate than the other two. Finally, the effect of geometric scale ratio, pressure difference, and the gas of the explosion overpressure is discussed. This paper can provide a relatively effective calculation method for shock wave overpressure for an airship envelope explosion.

Experimental Study on Vortex-Induced Vibration of Tension Leg and Riser for Full Depth Mooring Tension Leg Platform

According to the geometric parameters of the tension leg platform, the test model was made with a scale ratio of 1:61. The model was used to conduct the full-depth simulation test of uniform flow and wave current combination in the test pool. The model test results showed that when the reduced speed was between 5.5 and 8.5, and the lateral motion response of the platform was the most significant. In the interval of the reduced speed, the response frequency of transverse vortex-induced motion was close to the natural transverse frequency of the platform, and resonance occurred. The amplitude of surge motion increased with the increase of reduced speed. Due to the pull of the floating body, the tension of tension legs and risers increased with the flow rate but did not increase significantly in the floating body lock zone. The mooring tension had a certain limiting effect on the floating body sway. The displacement modes of tension legs and risers were greatly affected by the flow velocity. With the flow velocity increasing, the mode order increased. In addition, the increase in tension caused by the large displacement of the floating body had a certain impact on the displacement amplitude. The wave could reduce the sway of the floating body and strengthen the surge. Therefore, under the combined action of wave and current, the tension amplitude of the tension leg and riser was increased compared with that under the uniform flow. The conclusions obtained in this paper could be used for reference in the engineering design of tension legs and risers.

Scaling ratios for spectral accelerations caused by seismic site effect under site condition classifications in China

The spectral accelerations (Sa), which are widely used as ground motion inputs in structural seismic designing, are significantly affected by local site conditions classified by near-surface geology. A novel approach of quantifying the scaling ratios for Sa on site class I, II, III, and IV under the site condition classifications in Chinese seismic codes, was proposed. In this integrated approach, the scaling ratios for Sa on each site class were subordinated to three constituents, i.e., scaling ratios for peak ground acceleration (PGA), scaling ratios for PGA-normalized Sa, and non-linear decay exponents. The scaling ratios for peak ground acceleration were derived from recent studies and numerical simulations of 1,138 borehole models in China, the scaling ratios for PGA-normalized Sa were derived from 3,584 strong motion records in NGA West two database, and the non-linear decay exponents were derived from about 140 thousand borehole observation data recorded by KiK-net. Consequently, this approach was solidly based on statistics of observation data in company with numerical simulations, which resulted in more reasonable and more reliable scaling ratios for Sa caused by the seismic site effect under site condition classifications in China.

Lung de-recruitment in the allergic asthma of obesity: evidence from an anatomically based inverse model.

The increase in asthma associated with the obesity epidemic cannot simply be due to airway hyperresponsiveness from chronic lung compression because chronic lung compression is a feature of obesity in general. We therefore sought to investigate what other factors might be at play in the impaired lung function seen in obese individuals with asthma. We measured respiratory system impedance in four groups-Lean Control, Lean Allergic Asthma, Obese Control, and Obese Allergic Asthma-before and after administration of albuterol. Impedance measurements were fit with an anatomically based computational model of lung mechanics that represents the airway tree as a branching structure with a uniform degree of asymmetry and a fixed radius scaling ratio, γ, between branches of sequential order. The two model parameters that define the airway tree, γ and tracheal radius, varied only modestly between the four study groups, indicating relatively minor differences in airway caliber. In contrast, respiratory system elastance was 57, 34, 143, and 271 cmH2O/L, respectively, for the four groups, suggesting that obesity induced significant lung de-recruitment that was exacerbated by allergic asthma. In addition, when the radii of the individual branches of the airway tree were varied randomly, we found that roughly half the terminal airways had to be closed to have the model fit the data well. We conclude that de-recruitment of small airways is a particular feature of Obese Allergic Asthma, and this can be inferred from respiratory system impedance fit with an anatomically based computational model.NEW & NOTEWORTHY Using a novel anatomically based computational model to interpret oscillometry measurements of impedance, we show that respiratory system elastance is increased in obesity and is increased dramatically in individuals with obese allergic asthma. A significant component of this increased elastance in obese allergic asthma appears to be due to closure of small airways rather than alveolar atelectasis, and this closure is partially mitigated by albuterol. These findings potentially point to nonpharmacological therapies in obese allergic asthma aimed at recruiting closed airways.

Force-velocity profile in sprinting: sex effect.

The ability to produce muscle power during sprint acceleration is a major determinant of physical performance. The comparison of the force-velocity (F-v: theoretical maximal force, F0; velocity, v0 and maximal power output, Pmax) profile between men and women has attracted little attention. Most studies of sex differences have failed to apply a scaling ratio when reporting data. The present study investigated the sex effect on the F-v profile using an allometric model applied with body mass (BM), fat-free mass (FFM), fat-free mass of the lower limb (FFMLL), cross-sectional area (CSA) and leg length (LL) to mechanical parameters. Thirty students (15 men, 15 women) participated. Raw velocity-time data for three maximal 35m sprints were measured with a radar. Mechanical parameters of the F-v relationship were calculated from the modelling of the velocity-time curve. When F0 and Pmax were allometrically scaled with BM (p = 0.538; ES = 0.23) and FFM (p = 0.176; ES = 0.51), there were no significant differences between men and women. However, when the allometric model was applied to Pmax with FFMLL (p = 0.015; ES = 0.52), F0 with CSA (p = 0.016; ES = 0.93) and v0 with LL (p ≤ 0.001; ES = 1.98) differences between men and women persisted. FFM explained 83% of the sex differences in the F-v profile (p ≤ 0.001). After applying an allometric model, sex differences in the F-v profile are explained by other factors than body dimensions (i.e., physiological qualitative differences).

Wind tunnel and wave flume testing on directionality dynamic responses of a 10 MW Y-shaped semi-submersible wind turbine

Y-shaped semi-submersible platforms are typical supporting structures for floating wind turbines. The incompletely symmetric platforms may generate directionality dynamic responses in different wind/wave directions, and unfavorable responses will affect structural safety. Integrated and fine tests should be considered to find the dynamic response mechanisms in wind tunnel and wave flume (WTWF) laboratories. In this paper, the model test scheme of a 10 MW Y-shaped semi-submersible wind turbine with a 1:70 scale ratio is designed in WTWF; besides, the aero-hydro-elastic-servo dynamic numerical model is established on the open-source platform OpenFAST to verify the test results. First, the quality of the wind and wave fields is calibrated. Then, hydrostatic tests, wind-induced tests, wave-induced tests, and wind-wave combined tests are carried out. Finally, the dynamic responses and service performances of the floating wind turbine in different wind/wave directions are analyzed and compared in detail. The results show that the excellent wind and wave fields provide a successful basis for high-accuracy model tests. Wave/wind directions certainly affect the directionality dynamic responses of floating wind turbines. Specifically, the responses of the pitch, tower base loads, and nacelle acceleration in the 0° and 60° wave directions should be paid extra attention to, for its higher responses, which are related to structural safety and power generation efficiency. The directional dynamic responses should be fully determined before structural designs to benefit the operation and maintenance of Y-shaped semi-submersible wind turbines.

Artificial intelligence in predicting the bankruptcy of non-financial corporations

Research background: In a modern economy, full of complexities, ensuring a business' financial stability, and increasing its financial performance and competitiveness, has become especially difficult. Then, monitoring the company's financial situation and predicting its future development becomes important. Assessing the financial health of business entities using various models is an important area in not only scientific research, but also business practice. Purpose of the article: This study aims to predict the bankruptcy of companies in the engineering and automotive industries of the Slovak Republic using a multilayer neural network and logistic regression. Importantly, we develop a novel an early warning model for the Slovak engineering and automotive industries, which can be applied in countries with undeveloped capital markets. Methods: Data on the financial ratios of 2,384 companies were used. We used a logistic regression to analyse the data for the year 2019 and designed a logistic model. Meanwhile, the data for the years 2018 and 2019 were analysed using the neural network. In the prediction model, we analysed the predictive performance of several combinations of factors based on the industry sector, use of the scaling technique, activation function, and ratio of the sample distribution to the test and training parts. Findings & value added: The financial indicators ROS, QR, NWC/A, and PC/S reduce the likelihood of bankruptcy. Regarding the value of this work, we constructed an optimal network for the automotive and engineering industries using nine financial indicators on the input layer in combination with one hidden layer. Moreover, we developed a novel prediction model for bankruptcy using six of these indicators. Almost all sampled industries are privatised, and most companies are foreign owned. Hence, international companies as well as researchers can apply our models to understand their financial health and sustainability. Moreover, they can conduct comparative analyses of their own model with ours to reveal areas of model improvements.

Numerical and Experimental Investigation on the Scaling Law of Strip Model Foundation on Cohesionless Soils

In this study, a revised scaling law for laboratory test models of strip foundations on cohesionless soils is proposed. The centrifuge model tests were conducted on a strip model foundation at four different gravity levels (1 g, 5 g, 7.5 g, and 10 g), and the test results were used to calibrate numerical simulations. A set of numerical models were created to simulate full-scale tests and laboratory-scale tests. From the numerical simulations, the behavior of a foundation in the centrifuge model test is similar to that of the full-scale test but is different from the behavior in the laboratory-scale test under the 1 g condition. A parametric study was performed by varying the key variables that are internal friction angle, foundation width, and gravitational acceleration. The stress scale ratio is approximate to the geometric scale ratio in the 1 g model test. However, the settlement conversion requires both the geometric scale ratio and the settlement scale ratio newly proposed. The settlement scale ratio increases with increasing the internal friction angle and geometric scale ratio; accordingly, an equation for calculating the settlement scale ratio is proposed.

RFI-GAN: A reference-guided fuzzy integral network for ultrasound image augmentation

The Generative Adversarial Network (GAN) is commonly used for medical image augmentation, a method to alleviate the data shortage for downstream tasks. However, traditional GANs is not effective in mining the intrinsic association between samples and data space. Also, the multiple sections and variable scaling ratios of ultrasound images lead to inconsistency among images. The current GAN-based image generation methods cannot obtain the overall anatomical semantic constraints of inconsistent images, thus illogical images are generated. Therefore, a Reference-guided Fuzzy Integral GAN (RFI-GAN) is proposed. First, RFI-GAN implicitly constrains the logicality of the generated images through feature fusion between samples and reference set. These references, a kind of prior knowledge, cover most of the anatomical structures in the dataset. Second, as the general linear fusion takes features as additive and cannot fit the inconsistency of features, we generalize the additivity of features to non-additivity through the Fuzzy Integral, which is used to fusion non-additive measures. Two Fuzzy Integral Modules are proposed to nonlinearly fusion the texture and structure features of ultrasound images under the guidance of references. Finally, we perform experiments on the thyroid ultrasound image dataset, demonstrating the effectiveness of RFI-GAN in terms of generation and downstream classification tasks.

A Large-Scale Invariant Matching Method Based on DeepSpace-ScaleNet for Small Celestial Body Exploration

Small Celestial Body (SCB) image matching is essential for deep space exploration missions. In this paper, a large-scale invariant method is proposed to improve the matching accuracy of SCB images under large-scale variations. Specifically, we designed a novel network named DeepSpace-ScaleNet, which employs an attention mechanism for estimating the scale ratio to overcome the significant variation between two images. Firstly, the Global Attention-DenseASPP (GA-DenseASPP) module is proposed to refine feature extraction in deep space backgrounds. Secondly, the Correlation-Aware Distribution Predictor (CADP) module is built to capture the connections between correlation maps and improve the accuracy of the scale distribution estimation. To the best of our knowledge, this is the first work to explore large-scale SCB image matching using Transformer-based neural networks rather than traditional handcrafted feature descriptors. We also analysed the effects of different scale and illumination changes on SCB image matching in the experiment. To train the network and verify its effectiveness, we created a simulation dataset containing light variations and scale variations named Virtual SCB Dataset. Experimental results show that the DeepSpace-ScaleNet achieves a current state-of-the-art SCB image scale estimation performance. It also shows the best accuracy and robustness in image matching and relative pose estimation.

Analysis on the Vulnerability of a Tunnel Entrance under Internal Explosion.

Tunnels play an essential role in the transportation network. Tunnel entrances are usually buried at a shallow depth. In the event of an internal explosion, the blast pressure will cause severe damage or even collapse of the tunnel entrance, paralyzing the traffic system. Therefore, an accurate assessment of the damage level of tunnel entrances under internal blast loading can provide effective assistance for the anti-blast design of tunnels, post-disaster emergency response, and economic damage assessment. In this paper, four tunnel entrance specimens were designed and fabricated with a scale ratio of 1/5.5, and a series of field blast tests were carried out to examine the damage pattern of the tunnel entrances under internal explosion. Subsequently, static loading tests were conducted to obtain the maximum bearing capacity of the intact specimen and residual bearing capacities of the post-blast specimens. After that, an explicit non-linear analysis was carried out and a numerical finite element (FE) model of the tunnel entrance under internal blast loading was established by adopting the arbitrary Lagrangian-Eulerian (ALE) method and validated based on the data obtained from the field blast and static loading tests. A probabilistic vulnerability analysis of a typical tunnel entrance subjected to stochastic internal explosions (assuming various charge weights and detonation points) was then carried out with the validated FE model. For the purpose of damage assessment, the residual bearing capacity of the tunnel entrance was taken as the damage criterion. The vulnerability curves corresponding to various damage levels were further developed based on the stochastic data from the probabilistic vulnerability analysis. When the charge weight was 200 kg, the tunnel entrance exhibited slight or moderate damage, while the tunnel entrance suffered severe or even complete damage as the charge weight increased to 1000 kg. However, the tunnel entrance's probability of complete damage was less than 10% when the TNT charge weight did not exceed 1000 kg.

Labor misallocation and productivity growth in Vietnamese manufacturing firms

PurposeThis research identifies the level of labor misallocation in Vietnamese manufacturing sector for the period 2005–2019. The paper also examines the effects of labor misallocation on productivity in Vietnamese manufacturing firms controlled by industry- and firm-level factors.Design/methodology/approachThe level of labor misallocation and efficiency gains in total factor productivity (TFP) are assessed using Vietnam's annual enterprise survey data for the period 2005–2019 and Hsieh and Klenow (2009) productivity decomposition framework.FindingsThe results indicate four main points. Firstly, labor misallocation tends to increase from 2005 to 2019. Secondly, labor misallocation by firm ownership and technology level is found to be highest in state-owned enterprise and low-tech industries, whereas foreign direct investment and high-tech firms have lowest labor misallocation. Labor misallocation in small- and medium-sized enterprises is higher than in large-sized enterprises and is equivalent to overall sample. Thirdly, labor misallocation decreases productivity in manufacturing firms. The firm-level factors such as bigger technology gap, external capital, firm scale and poor liquidity ratio decrease productivity in manufacturing firms. Whereas firm-level factors such as Vietnam's accession to the WTO, reasonable corporate tax structure, capital intensity, human capital and firm age increase productivity of manufacturing firms. The industry-level factors such as FDI horizontal, forward and supply backward spillovers promote productivity from foreign firms to domestic ones. Meanwhile, only backward linkages reduce productivity of firms. Finally, by difference-in-differences (DID) method, the result indicates foreign firms have higher average labor productivity than domestic firms before or after Vietnam's accession to the WTO. After joining WTO, the average labor productivity of foreign firms is increased by 854 million VND while the average labor productivity of domestic firms is increased by 895 million VND. The DID between the two groups (domestic firms and foreign firms) before and after Vietnam's accession to WTO is 41 million dong.Research limitations/implicationsThe main limitation of the study is that the market is assumed perfectly competitive. The model focuses on selective factors affecting labor productivity.Originality/valueThe focus of many previous international research papers was generally to look at the level of labor misallocation in developed countries. However, knowledge about labor misallocation is limited, particularly in the context of developing countries. This paper examines the level of labor misallocation by region, ownership, level of technology and firm size on productivity and the effect of misallocation on productivity in Vietnamese manufacturing firms.Peer reviewThe peer-review history for this article is available at: https://publons.com/publon/10.1108/IJSE-09-2021-0552.