Spread Of Flow Research Articles

The Fire Resistance of Transformable Barriers: Influence of the Large-Scale Factor

The paper presents the results of the development of a multi-layer protective product, which is a transformable fire barrier, installed in buildings and structures to limit the spread of flame, heat flow and smoke. Based on the results of the simulation of eight samples of fire curtains, three promising samples of different compositions were selected, demonstrating a fire resistance limit on the loss of thermal insulating capacity (I) of 30 min. During the small-scale tests, it was found that the multilayer fabric of the following composition was promising: heat-treated silica fabric, aluminum foil, mineral fiber heat insulation material, stitched by needle-punching with silica thread, fabric reinforced with fiberglass mesh and stitched through with basalt thread, with seams treated with a fire-resistant elastic sealant. According to the results of a standard large-scale experimental study, a fire curtain with a loss of integrity not less than 60 min, and a loss of thermal insulating ability not less than 15 min were obtained. The results of the study assess the impact of the scale factor on the fire resistance limit of fire curtains in a fire.

Accident Detection and Flow Prediction for Connected and Automated Transport Systems

Effective accident detection and traffic flow forecasting are of great importance for quick respond, impact elimination and intelligent control of the traffic flow consisting of autonomous vehicles. This paper proposes a traffic accident detection method for connected and automated transport systems by conducting a grid-based parameter extracting and SVC-based traffic state classification. Allowing for the dynamic spread of traffic flow over time, from upstream to downstream and from accident lanes to other lanes, a spatiotemporal Markov model is established to predict the evolution of traffic flow after accident by introducing the grid as state detection unit and fitting the spatiotemporal evolution with the parameter space mean speed to match the need of both detection accuracy and monitoring scope. Compared with actual accident data, the validation results indicate that the proposed methods present a good performance in accident detection with the accident detection rate as 87.72% and a higher precision rate than both SVM (support vector machine) and ANN (artificial neural network) models in traffic flow prediction. With the active traffic accident identification and dynamic traffic flow prediction, it is beneficial to shorten detection time, reduce possible impacts of traffic accidents and carbon emissions from congestion. The methods can be implied to traffic state recognition and traffic flow prediction, which is one of the significant sections of connected and automated transport systems, and serve as references for accident handling and urban traffic management.

Putative cause of seizure-induced cognitive alterations: The oscillatory reconfiguration of seizure network.

The dynamic reconfiguration of network oscillations is connected with cognitive processes. Changes in how neural networks and signaling pathways work are crucial to how epilepsy and related conditions develop. Specifically, there is evidence that prolonged or recurrent seizures may induce or exacerbate cognitive impairment. However, it still needs to be determined how the seizure brain configures its functional structure to shape the battle of strong local oscillations vs. slow global oscillations in the network to impair cognitive function. In this paper, we aim to deduce the network mechanisms underlying seizure-induced cognitive impairment by comparing the evolution of strong local oscillations with slow global oscillations and their link to the resting state of healthy controls. Here, we construct a dynamically efficient network of pathological seizures by calculating the synchrony and directionality of information flow between nine patients' SEEG signals. Then, using a pattern-based method, we found hierarchical modules in the brain's functional network and measured the functional balance between the network's local strong and slow global oscillations. According to the findings, a tremendous rise in strong local oscillations during seizures and an increase in slow global oscillations after seizures corresponded to the initiation and recovery of cognitive impairment. Specifically, during the interictal period, local strong and slow global oscillations are in metastable balance, which is the same as a normal cognitive process and can be switched easily. During the pre-ictal period, the two show a bimodal pattern of separate peaks that cannot be easily switched, and some flexibility is lost. During the seizure period, a single-peak pattern with negative peaks is showcased, and the network eventually transitions to a very intense strong local oscillation state. These results shed light on the mechanism behind network oscillations in epilepsy-induced cognitive impairment. On the other hand, the differential (similarity) of oscillatory reorganization between the local (non) epileptogenic network and the global network may be an emergency protective mechanism of the brain, preventing the spread of pathological information flow to more healthy brain regions.

Migratory birds as the vehicle of transmission of multi drug resistant extended spectrum β lactamase producing Escherichia fergusonii, an emerging zoonotic pathogen

The acquisition of multi-drug resistance (MDR) genes by pathogenic bacterial bugs and their dispersal to different food webs has become a silent pandemic. The multiplied use of different antibacterial therapeutics during COVID-19 pandemic has accelerated the process among emerging pathogens. Wild migratory birds play an important role in the spread of MDR pathogens and MDR gene flow due to the consumption of contaminated food and water. Escherichia fergusonii is an emerging pathogen of family Enterobacteriaceae and commonly causes disease in human and animals. The present study focused on the isolation of E. fergusonii from blood, saliva, and intestine of selected migratory birds of the Hazara Division. The sensitivity of isolated strains was assessed against ten different antibiotics. The isolation frequency of E. fergusonii was 69%. In blood samples, a high rate of resistance was observed against ceftriaxone (80%) followed by ampicillin (76%) whereas, in oral and intestinal samples, ceftriaxone resistant strains were 56% and 57% while ampicillin resistance was 49% and 52% respectively. The overall ceftriaxone and ampicillin-resistant cases in all three sample sources were 71% and 65% respectively. In comparison to oral and intestinal samples, high numbers of ceftriaxone-resistant strains were isolated from the blood of mallard while ampicillin-resistant strains were observed in blood samples of cattle egrets. 16S rRNA-based confirmed strains of E. fergusonii were processed for detection of CTX-M and TEM-1 gene through Polymerase chain reaction (PCR) after DNA extraction. Hundred percent ceftriaxone resistant isolates possessed CTX-M and all ampicillin-resistant strains harbored TEM-1 genes. Amplified products were sequenced by using the Sanger sequencing method and the resulted sequences were checked for similarity in the nucleotide Database through the BLAST program. TEM-1 gene showed 99% and the CTX-M gene showed 98% similar sequences in the Database. The 16S rRNA sequence and nucleotide sequences for TEM-1 and CTX-M genes were submitted to Gene Bank with accession numbers LC521304, LC521306, LC521307 respectively. We posit to combat MDR gene flow among the bacterial pathogens across different geographical locations, regular surveillance of new zoonotic pathogens must be conducted.

Analyzing the Filling Ability Property of Self-Compacting Concrete Using Fly Ash and Superplasticizer

Self-compacting concrete (SCC) is an innovative concrete which can flow and consolidate under its own weight without any vibration. It can also resist segregation. This kind of concrete is durable and environment friendly. Deformability and stability are also the major characteristics of self-compacting concrete. To achieve such properties, it is essential to develop a method for mix design of SCC. The cost of concrete can be minimized by substituting cement with material like fly ash. Properties of materials have effect on the flow behavior of SCC. Hence it is vital to determine the right quantities of material such that the concrete can flow without segregation. This paper presents an experimental course of actions for the investigation of filling ability property of self-compacting concrete. Nine trial mixes have been conducted in order to upgrade the flow value as well as flow time and the interaction between fine aggregate, coarse aggregate, cement, fly ash as well as superplasticizer has been closely observed. The high flowability is attained by exchanging cement with fly ash at different percentages along with varying superplasticizer content. Flowability is a means for a concrete’s filling ability which is determined in terms of spread of slump flow by using a slump flow test. The viscosity, measured indirectly by T500 test by visually observing the time required at which concrete spreads. Guidelines given by EFNARC are followed here.

Reduction of Motion Artifacts From Remote Photoplethysmography Using Adaptive Noise Cancellation and Modified HSI Model

Remote photoplethysmography (rPPG) is a method to measure cardiac activities without any contact sensors. Non-contact sensors include radar, laser, and digital cameras, and there have been wide developments regarding the measurement of rPPG signals using continuous face frames. However, non-contact sensors are quite sensitive to the subject’s motion, which causes motion artifacts. In this paper, two hypotheses are proposed: a) the motion artifacts are caused by unevenly reflected light due to the curvature of the subject’s face; and b) melanin and residuals in the continuous face frames are time-varying values whenever the subject’s movement is triggered. Adaptive noise cancellation based on recursive least square (ANS based on RLS) using the Lambert-Beer law and the hue–saturation–intensity (HSI) model were applied. The former is used for skin modeling, and the latter is used to reduce noises derived by the curvature of the face. Furthermore, the proposed algorithm is directly applied to two-dimensional continuous face frames and results in the rPPG signal and rPPG image, respectively. To evaluate proposed algorithm, two different experiments (e.g., static and dynamic situation) were conducted. Furthermore, in a study with 15 participants, the performances of heart rate estimation and heart rate variability (HRV) were evaluated by comparing the proposed method with previously developed methods. The results showed that a) the artifacts derived by head movement are efficiently removed, compared to previous methods; and b) rPPG images describing the spread of facial blood flow are acquired in real-time.

Effects of Changes of Lake Victoria Water Levels on Land Use Patterns, Covid-19 Pandemic and Food Security in Winam Gulf, Homa-Bay County, Kenya

The study was carried out on the Southern shore of Winam Gulf, Homa Bay County, Kenya. It was aimed at establishing the relationship among changes of Lake Victoria water levels, land use patterns and food security during the COVID-19 pandemic. Empirical studies involving ground point survey was used to determine the extent of spread of the back flow and vertical rise of the lake’s waters from five pier and nine beach survey points between July 2019 to October 2020. In-depth interviews and questionnaires were also used to collect data which were analyzed using descriptive statistics and Likert’s scale. The average variations of the extent of the back flow was approximately 294m while the vertical change in the water levels along the pier points was 1.03m. This led to submergence of the adjacent land use patterns and interfered with food security in the region. Coupled with the impacts of COVID-19 pandemic, majority (209) of the respondents substituted their meals and a quarter (79) of the them reduced their number of meals per day. A strong positive perception on the responses by the Government of Kenya and County Government Homa Bay towards addressing the pandemic with the Likert’s scale summative perception index of 381 very effective, 328 effective and 363 satisfactory were realized. The study recommends: observance and execution of environmental laws governing settlement on riparian lands, proactive compliance with the warnings and advice from the meteorological department, and adoption of alternative land use patterns.

Visualizing the relationship between geographic and social media network space

This research explores the relationship between geographic and social media network space. The purpose of this paper is twofold: to perform a geo-enhanced network analysis and to create an example social media network using a select location identified in the study area as important in the results of the geo-enhanced network analysis. A straightforward, non-technical example is provided to the readers on how location data and social media network data can be overlaid to visualize potential local firm to firm and firm to customer connections in geographic and social media network space. An example of how to identify these potential connections locally through social media networks using Twitter is demonstrated. By considering the geographic location in network structures, it is possible to convey the role distance plays in discerning prospective local social media marketing partners, and also track the spread of information flow through social media networks.

Study of gas consumption patterns for sheet glass enterprises

A study of the gas consumption modes of the subgroup “Enterprises of construction industry and architecture” of the regional gas supply system, as well as the production of sheet glass, which forms gas consumption in the subgroup by 94%, was carried out. The field type “daily gas consumption outside temperature” is set for the subgroup and the plant for production of sheet glass. This is a field with a weak dependence on the growth of daily gas consumption when outside temperature decreases and without an obvious stratification into temperature regions determined by the state of the heating system (“on” or “off”) and a significant vertical spread of daily gas flow at the same values of outside temperature. Additional factors affecting gas consumption were searched. The created database of 14 technological indicators over a seven-year period allowed to identify factors forming daily and annual gas consumption regimes using correlation-regression analysis. The importance of the “time worked by the line” factor and its contribution to the formation of the annual volume of gas consumption was assessed. Invention proposes a simplified method of estimating the rate of aging of furnace lining and wear of enclosing structures on the basis of a single-factor model of gas consumption from productivity by comparing the daily average annual values of specific gas consumption for sheet glass production with the same volume of output.

Coupling Computational Fluid Dynamics Simulations and Statistical Moments for Designing Healthy Indoor Spaces.

Cross-contamination between occupants in an indoor space may occur due to transfer of infectious aerosols. Computational fluid dynamics (CFD) provides detailed insight into particle transport in indoor spaces. However, such simulations are site-specific. This study couples CFD with statistical moments and establishes a framework that transitions site-specific results to generating guidelines for designing “healthy” indoor spaces. Eighteen cases were simulated, and three parameters were assessed: inlet/outlet location, air changes per hour, and the presence/absence of desks. Aerosol release due to a simulated “sneeze” in a two-dimensional ventilated space was applied as a test case. Mean, standard deviation, and skewness of the velocity profiles and particle locations gave an overall picture of the spread and movement of the air flow in the domain. A parameter or configuration did not dominate the values, confirming the significance of considering the combined influence of multiple parameters for determining localized air-flow characteristics. Particle clustering occurred more when the inlet was positioned above the outlet. The particle dispersion pattern could be classified into two time zones: “near time”, <60 s, and “far time”, >120 s. Based on dosage, the 18 cases were classified into three groups ranging from worst case scenario to best case scenario.

Assessing Rheological Properties of Cement Paste as a First Step in Predicting Robustness of Self-compacting Concrete

This paper proposes a methodology to assess the rheological behavior of cement paste as a first step to linking this behavior to the robustness of the Self Compacting Mortar (SCM) and further extending this to Self-Compacting Concrete (SCC). Cement paste�s rheological behavior was assessed in terms of spread (using a mini-cone) and time of flow (using the Marsh cone). The results show that the type of superplasticizer (SP) admixture has a great influence on the rheological behavior of cement paste and for each combination of binder and superplasticizer admixture there is a specific range of water to binder ratio in which the rheology of paste seems to be appropriate for obtaining a robust SCC mix. The influence of SP and limestone filler addition on the kinetic of cement hydration process was assessed by X Ray Diffraction and thermal analysis (TG-DTA). Based on these results, i.e. an important delaying effect exerted by superplasticizer additions on cement hydration process at early ages (1 day), it can be concluded that when designing SCC for the precast industry - where the early strength of concrete is of high importance, analyzing the early strength of binder paste together with the robustness properties is very important. The correlation between the two aspects - rheology and early strength -is very important in this case in order to obtain applicable results in practice.

Numerical Simulation on the Effect of Cooling Hole Configuration on the Film Cooling Effectiveness in TBC Coated Turbine Vanes

Abstract Numerical simulation was performed to investigate adiabatic film cooling effectiveness of cooling holes over thermal barrier coated superalloy substrate. Divergent, convergent-divergent and curved configuration of cooling holes were compared with the inclined cylindrical hole configuration. The coolant flow was strongly attached with the surface for 35º inclination. The film cooling effectiveness at different blowing ratios of 0.4, 0.8 and 1.2 was analysed. The study was carried out using realizable k-ϵ (RKE) model. The curved hole configuration provided enhanced cooling effectiveness even at 0.8 blowing ratio in comparison with other cases. The presence of curvature reduced the coolant velocity thereby preventing the detachment of jet from the surface and forming a very strong longitudinal film. The coolant jet starts detaching from the surface for blowing ratio higher than 1.2; the high momentum of the film cooling jet causes a lift off the surface. At 1.2 blowing ratio, a greater spread of coolant flow along the test surface was observed. Better film cooling effectiveness was evident at 0.8 and 1.2 blowing ratios. At 0.8, the enhancement in the overall film cooling effectiveness of divergent, convergent-divergent and curved hole configuration was about 14 %, 50 % and 59 %, respectively.

The influence of tributary flow density differences on the hydrodynamic behavior of a confluent meander bend and implications for flow mixing

The goal of this study is to evaluate the influence of tributary flow density differences on hydrodynamics and mixing at a confluent meander bend. A detailed field characterization is performed using an Acoustic Doppler Current Profiler (ADCP) for quantification of the 3D flow field, flow discharge and bathymetry, as well as CTD measurements (conductivity, temperature, depth) to characterize the patterns of mixing. Satellite images of the confluence taken at complementary times to the field surveys were analyzed to evaluate the confluence hydrodynamics at different flow conditions.The results illustrate the differences in hydrodynamics and mixing length in relation to confluences with equal density tributaries. At low-density differences, and higher discharge ratio (Qr) between the two rivers, the flow is similar to equi-density confluent meander bends. In contrast, at high-density differences (low Qr), the tributary flow is confined to near the confluence but the density difference causes the flow to move across channel. In this case, the density difference causes the lateral spread of the tributary flow to be greater than at a greater Qr when the density difference is less. These results illustrate the potential importance of density differences between tributaries in determining the rate and spatial extent of mixing and sediment dispersal at confluent meander bends.

The Structured Coalescent and Its Approximations.

Phylogeographic methods can help reveal the movement of genes between populations of organisms. This has been widely done to quantify pathogen movement between different host populations, the migration history of humans, and the geographic spread of languages or gene flow between species using the location or state of samples alongside sequence data. Phylogenies therefore offer insights into migration processes not available from classic epidemiological or occurrence data alone. Phylogeographic methods have however several known shortcomings. In particular, one of the most widely used methods treats migration the same as mutation, and therefore does not incorporate information about population demography. This may lead to severe biases in estimated migration rates for data sets where sampling is biased across populations. The structured coalescent on the other hand allows us to coherently model the migration and coalescent process, but current implementations struggle with complex data sets due to the need to infer ancestral migration histories. Thus, approximations to the structured coalescent, which integrate over all ancestral migration histories, have been developed. However, the validity and robustness of these approximations remain unclear. We present an exact numerical solution to the structured coalescent that does not require the inference of migration histories. Although this solution is computationally unfeasible for large data sets, it clarifies the assumptions of previously developed approximate methods and allows us to provide an improved approximation to the structured coalescent. We have implemented these methods in BEAST2, and we show how these methods compare under different scenarios.

Directional spread of activity in synaptic networks of the human lateral amygdala

Spontaneous epileptiform activity has previously been observed in lateral amygdala (LA) slices derived from patients with intractable-temporal lobe epilepsy. The present study aimed to characterize intranuclear LA synaptic connectivity and to test the hypothesis that differences in the spread of flow of neuronal activity may relate to spontaneous epileptiform activity occurrence.Electrical activity was evoked through electrical microstimulation in acute human brain slices containing the LA, signals were recorded as local field potentials combined with fast optical imaging of voltage-sensitive dye fluorescence. Sites of stimulation and recording were systematically varied. Following recordings, slices were anatomically reconstructed using two-dimensional unitary slices as a reference for coronal and parasagittal planes. Local spatial patterns and spread of activity were assessed by incorporating the coordinates of electrical and optical recording sites into the respective unitary slice.A preferential directional spread of evoked electrical signals was observed from ventral to dorsal, rostral to caudal and medial to lateral regions in the LA. No differences in spread of evoked activity were observed between spontaneously and non-spontaneously active LA slices, i.e. basic properties of evoked synaptic responses were similar in the two functional types of LA slices, including input–output relationship, and paired-pulse depression.These results indicate a directed propagation of synaptic signals within the human LA in spontaneously active epileptic slices. We suggest that the lack of differences in local and in systemic information processing has to be found in confined epileptiform circuits within the amygdala likely involving well-known “epileptic neurons”.

Sistema de seguridad ante sobrecargas en un subsolador

Currently, rural technological development has emerged as a response to the need for improving production efficiency in the fields, especially in agricultural countries such as Colombia due to aspects such as demographic growth and economic globalization; the use of a subsoiler is the first activity performed, intended to loosen soil as a way of reducing its resistance and allowing the spread of plant roots and flow of water. Hence, any type of abnormal circumstances in the development of this activity results in delays in future works or decrease of crop efficiency. This article shows the results of a technological research, focused on mechatronic adequacy of a subsoiler implement addressed under a structured design procedure that assures technological adaptations by assuring the operation of a control instrumented system with response to overloading

An Analytical Model of the DC and Frequency-Dependent 2-D and 3-D Current Spreading in Forward-Biased Shallow p-n Junctions

We present an analytical model of the 2-D/3-D spreading of dc and small-signal minority carrier flow in forward-biased shallow finite-sized p-n junctions. The model achieves an analytical solution of the 2-D/3-D continuity equation by replacing a Dirichlet–Neumann mixed boundary condition by a Neumann condition. It expresses the current spreading in terms of the junction width, lateral (vertical) extent beyond the junction, diffusion length, lifetime, transit time, and frequency. It predicts that the small-signal spread of the minority carrier flow gets progressively restricted for frequencies greater than inverse lifetime in long diodes and inverse transit time in short diodes; at high frequencies, the minority carrier flow picture consists of a 1-D small-signal flow superposed over a 2-D/3-D dc flow. Under dc conditions, the flow is almost 1-D in short diodes, spreads with an increase in vertical extent, and saturates in long diodes. We give the critical lateral extent beyond which the spread saturates, in terms of the vertical extent. Our model includes a small-signal equivalent circuit, which considers both minority and majority carrier current spreading; the latter is frequency independent and becomes important at higher frequencies. We validate the model against numerical simulations, and show its application to a rectangular junction with rounded corners.

선박 구조 개선을 통한 승무원의 피난 효율 향상을 위한 연구

Abstract : Onshore great fires can normally be extinguished by firefighters using special firefighting equipment and its suitable method. However, offshore fires on the ships are to be extinguished by the crew without any supports from the onshore. Also, crews working on board are exposed to high risk of emergency evacuation due to the complicated structure arrangement of the ships and different accident types such as fire and ship collisions. As most of damage and loss of life in fire are associated with suffocation, shortening of evacuation time is an important factor to improve a survival rate. In this study, visibility in the accommodation area is analyzed by using the temperature and smoke flow which are obtained by the Fire Dynamic Simulator(FDS) as a Three-Dimensional Fire Analysis program to understand the survival rate of the crew upon the fire. The fire doors for most of ships are designed to close automatically when the fire alarm is activated. These auto-matic closing of the fire doors is a very effective system to delay the spread of flame and smoke flow for the unmanned spaces of the fire protected area. However, if the crew cannot escape within the estimated

A passive cable to excite oligodendrocyte precursor glia

A passive cable to excite oligodendrocyte precursor glia

Redirection and channelization of power-law fluid flow in a rough-walled fracture

Flow of non-Newtonian fluids in rough-walled rock fractures is common in many technological processes in oil and gas industry. A numerical study of power-law fluid flow in rough-walled fractures is carried out under the assumptions of the lubrication theory approximation. It is shown that, in a self-affine fracture, varying the exponent of the power-law fluid may lead to a redirection of flow compared to a Newtonian fluid flow field. This effect is observed even though the fracture landscape is isotropic, i.e. no preferential flow paths have been created in the model by e.g. relative displacement of the fracture faces. In another fracture, one that contains an obstacle represented by a spot of zero aperture, the spread of the flow around the obstacle is again controlled by the power exponent of the fluid. The fluid being more shear-thinning leads to a channelization of the flow in such a fracture. “Channelization” here refers to the fluid velocity component in the direction of the applied pressure gradient becoming larger as compared to the velocity component in the direction normal to the overall flow direction as the fluid becomes more shear-thinning. A channelization is also observed in a fracture containing a local zone of an elevated aperture. The effects of rheology on the spread and redirection of flow in a fracture of variable aperture are crucial for optimization of transport and placement of particles or tracers in natural and man-made fractures.