Sudden Flow Research Articles

Subway Sudden Passenger Flow Prediction Method Based on Two Factors: Case Study of the Dongsishitiao Station in Beijing

A sudden increase in passenger flow can primitively lead to continuous congestion of a subway network and thus have a profound impact on the subway system. To prevent the risk caused by sudden overcrowding, the prediction of passenger flow is a daily task of the rail transit management. Most current short-term passenger flow forecasts rely only on inbound passenger flow, which cannot accurately characterize the total impact of sudden passenger flow. To enhance the prediction accuracy, we propose a sudden passenger flow prediction model with two factors, the outbound and inbound passenger flows. The wavelet neural network (WNN) model was used to detect the sudden passenger flow, and subsequently, it is optimized by the genetic algorithm (GA), according to two-factor data characteristics. Sudden passenger flow events from 2014 to 2016 in the Beijing Dongsishitiao Station (DS) were used to train and verify the reliability of the prediction model. The optimized WNN results proved better than the conventional WNN, and the error of models based on two factors was significantly smaller than the models with a single-factor.

Turbulent flow of liquid lead alloy in oxygen-controlled corrosion erosion test facility

The CORELLA (CORrosion Erosion test facility for Liquid Lead Alloy) facility allows corrosion erosion tests in molten lead alloys at controlled oxygen content and temperature under flowing conditions. Its exposure chamber consists of a cylindrical container, partially filled with the liquid metal. An inner rotating cylinder drives the liquid metal flow. The specimens of interest are fixed vertically inside the chamber such that the lead alloy flows around the specimens on both sides. In this numerical study, the turbulent flow of liquid lead–bismuth eutectic is solved for various specimen configurations, filling heights, and rotational speeds of the inner cylinder. Hereby, the deformation of the free liquid surface is taken into account using a rotationally symmetric approximation. Highly turbulent flow is found even for 200 rpm (revolutions per minute), the lowest rotational speed investigated. The velocity of the liquid metal along the specimens’ lateral surfaces reaches values up to 1.5 m/s for a rotational speed of 1200 rpm, the limit of experimentally stable conditions. Due to the sudden flow constrictions and expansions around the specimens, a much higher effect of the flow on corrosion erosion is expected than for simple pipe flow at the same bulk velocity.

Financial Development, Financial Openness and Economic Growth in Nigeria

This study examined the impact of financial development and financial openness on economic growth in Nigeria between 1981 and 2019. This was done through the use of the Auto-Regressive Distributed Lag (ARDL) model. In doing this, the ratio of credit to the private sector to the GDP and broad money to narrow money were used as measures of financial development and financial openness respectively. The study found that financial development has a positive and insignificant impact on economic growth in Nigeria in the long and short-run. The study also found that financial openness has a negative and insignificant impact on economic growth in Nigeria in the long-run. The results of the study further revealed that simultaneous existence of financial development and financial openness has an insignificant but positive impact on economic growth in Nigeria in the long-run. Based on the findings, the study recommended that the CBN should increase its efforts towards the regulation and supervision of the financial sector to reduce the incidence of financial distress. The study also recommended that efforts to develop the mortgage and insurance sector and the capital market should be intensified through regulatory improvements, improvements in the instruments in use in the market as well as public enlightenment programs to increase awareness of the potentials of the mortgage, insurance and capital markets. The final recommendation made by the study is that more restrictions should be placed on the inflow of capital in and out of the country to guard against sudden capital flow reversals.

On the modeling of mechanotransduction in flow-mediated dilation

In this paper, we report a physics based mathematical model to describe the mechanotransduction at the luminal surface of the brachial artery during a flow-mediated dilation (FMD) process. To account for the effect of the released vasodilators in response to the sudden blood flow resurgence, a scalar property is introduced as a signal radially diffusing through the arterial wall, locally affecting its compliance. The model was evaluated on 19 in vivo responses of brachial artery FMD (BAFMD) in 12 healthy subjects. It successfully reproduces the time-dependent dilation of the brachial artery. The predicted artery's outer-to-inner radius ratio was also found to be consistent with the measurements within an acceptable margin of error. Physically meaningful dimensionless parameters quantifying the artery's physical state arose from the model, providing a description to how sensitive or responsive the artery is to the changes of wall shear stress (WSS). Future applications of this model, via incorporating inexpensive, relatively quick, and non-invasive imaging, could potentially help detect early stages of developing forms of cardiovascular diseases.

Sudden passenger flow characteristics and congestion control based on intelligent urban rail transit network

The development of smart city is of strategic significance to the realization of modern society in China, and rail transit network is an important part of urban development. Currently, China's urban rail transport is at the bottleneck stage, and many medium-sized cities are facing a sudden heavy passenger congestion situation. Based on the next-generation innovation of the knowledge society, smart cities will maximize the use of new generation information technology in all fields of the city, and realize advanced urban informatization that realizes deep integration of informatization, industrialization, and informatization and helps to reduce urbanization and "disease in big cities." Improve the quality of urbanization, realize refined and dynamic management, and enhance the effectiveness of urban management and improve the quality of life of citizens. In order to ensure the safety of passengers, passenger flow control and optimization and upgrading of rail transit network become urgent. However, there are few researches in this field in China, so this paper will focus on the characteristics of sudden passenger flow and congestion control based on smart city rail transit network. First, in this paper, we systematically explained the relationship between smart cities and smart transportation and analyzed the need for sudden passenger flow control in urban railway transportation according to its characteristics. According to a study on the characteristics of sudden passenger flow, this paper believes that passenger flow comes primarily from large-scale activities, commuters, and individual emergencies, but is still predictable and controllable. For this reason, this paper studies the control scheme of sudden passenger flow congestion, which fully combines the characteristics of sudden passenger flow, and according to the characteristics of the treatment. This scheme is safe and reliable and has the advantage of controlling congestion from the source. In order to further test the actual effect of the passenger flow control scheme, the simulation experiment is carried out in the end of this paper. According to experimental data analysis, the passenger flow control method of this paper can effectively improve the existing rail transport congestion control in the case of sudden large-scale passenger flow, and the effect is remarkable, and most of them. Suitable for urban rail transport networks.

A-DECS: Enhanced collaborative edge–edge data storage service for edge computing with adaptive prediction

Due to the rapid development of IoT and 5G technologies, end-users of the Internet are generating a sea of data, which burdens the cloud cores and data centers. The urgent traffic demand causes a bad quality of experience in the traditional reactive networks. With the improvement of hardware, the edge of the Internet can share some responsibility for cloud servers. In small-scale scenarios, offload computing and storage tasks to edge nodes can help improve the user experience and utilize resources of the edge networks. In this paper, we propose a collaborative edge–edge data storage service with adaptive prediction called A-DECS based on our previous work DECS (Zhou and Chen, 2020) in local area scenarios. It manages nodes in the edge network and fully utilizes the limited resources in the cluster. A-DECS picks the most appropriate node to offload tasks. It can also proactively replicate popular data and generate forwarding rules in advance. A-DECS can reduce the read latency of cold-start and sudden peak flow situations. We compare it to state-of-the-art research. This experiment result proves that A-DECS is more suitable for edge clusters due to its lower latency and better resource utilization.

Experimental analysis of Reynolds effect on flow detachment and sudden flow release on a wall-mounted hump

The boundary layer detachment limits compact power plants' operation at moderate Reynolds number in adverse pressure conditions. Flow detachment is promoted by the lack of momentum in the near-wall region when exposed to adverse pressure gradients. Transient flows or periodic flow perturbations may delay or prevent the flow detachment. The present investigation experimentally analyzes the behavior of separated flows based on an ad-hoc wall-mounted hump. The near wall flow region detachment and recirculated flow evolution under sudden flow release were experimentally characterized. The extension of the separated region and its dynamic development were monitored through surface pressure, temperature measurements, and hot-wire traverses. Comparing the 3D hump performance during steady state experiments against sudden flow acceleration runs, we report for the first time the temporal response of a diffusive passage exposed to a sudden flow acceleration and the impact of the acceleration on the boundary layer detachment. Due to the sudden flow release, the near-wall region can overcome the adverse pressure gradient. However, as the flow acceleration dilutes, the boundary layer detaches, and the recirculated flow region develops. The comparison of experimental results against 3D transient Computational Fluid Dynamics simulations, using the standard gas turbine industry approach, demonstrates the ability of Unsteady Reynolds Averaged Navier-Stokes models to predict the dynamic performance of this phenomenon.

An image of death in dinosaur faces caught in a pyroclastic flow from a local sub-event of the Chicxulub impact

The following paper builds on already observed dinosaur remains killed in a volcanic eruption linked to the Chicxulub in the area of Valbonne in south eastern France. The Chicxulub impact catapulted a number of sub-blocks from the crust around its impact area in the Yucatan far from it, their brutal landing triggered smaller tectonic waves. In Valbonne, which is a marginal area of the older Alpine volcanic arc, the dormant volcanism was waked up, as the block itself had been catapulted from the sea floor and was heavily hydrated, causing powerful and sudden pyroclastic flows with a mild temperature and catastrophic amounts of mud materials, intermediary to a lahar, which surprised a large number of dinosaurs. Their bodies were partly burned and aplasted and partly filled up with tephras mixed with hot materials from the impact, or andesitic mud-lava for farther away creatures.

Financial Development, Financial Openness and Economic Growth in Nigeria

This study examined the impact of financial development and financial openness on economic growth in Nigeria between 1981 and 2019. This was done through the use of the Auto-Regressive Distributed Lag (ARDL) model. In doing this, the ratio of credit to the private sector to the GDP and broad money to narrow money were used as measures of financial development and financial openness respectively. The study found that financial development has a positive and insignificant impact on economic growth in Nigeria in the long and short-run. The study also found that financial openness has a negative and insignificant impact on economic growth in Nigeria in the long-run. The results of the study further revealed that simultaneous existence of financial development and financial openness has an insignificant but positive impact on economic growth in Nigeria in the long-run. Based on the findings, the study recommended that the CBN should increase its efforts towards the regulation and supervision of the financial sector to reduce the incidence of financial distress. The study also recommended that efforts to develop the mortgage and insurance sector and the capital market should be intensified through regulatory improvements, improvements in the instruments in use in the market as well as public enlightenment programs to increase awareness of the potentials of the mortgage, insurance and capital markets. The final recommendation made by the study is that more restrictions should be placed on the inflow of capital in and out of the country to guard against sudden capital flow reversals.

Effects of Killari earthquake on the paleo-channel of Tirna River Basin from Central India using anisotropy of magnetic susceptibility

The Killari Earthquake (Moment magnitude 6.1) of September 30, 1993, occurred in the state of Maharashtra, India, has an epicenter (18°03′ N, 76°33′ E) located at ~ 40 km SSW of Killari Town. The ~ 125 km long basin of Tirna River, close to the Killari Town, currently occupies the area that has witnessed episodic intra-cratonic earthquakes, including the Killari Earthquake, during last 800 years. The anisotropy of magnetic susceptibility (AMS) study was performed on ~ 233 soft sedimentary core samples from six successions located in the upper to lower stream of the Tirna River basin in the present study in order to evaluate the effects of earthquake on the river flow dynamics and its future consequence. The AMS Kmax orientations of the samples from the upper reach of the river section suggest that the sedimentation in this part of the river was controlled by a N–S to NNW–SSE fluvial regime with a low or medium flow velocity. In the middle reaches of the basin, an abrupt shift in the palaeo-flow direction occurred to W–E with low velocity flow. However, a NW–SE higher palaeo-flow regime is identified in the following central part of the basin in down-stream direction, followed by a low-velocity palaeo-flow regime at the lower reach of the Tirna basin. We attribute the sudden high flow velocity regime in the central part of the river basin to an enhanced gradient of the river that resulted from the reactivation of a NW–SE fault transecting the Tirna River basin at the Killari Town. As the NW–SE faulting in regional scale is attributed as the main cause of Killari Earthquake, the reactivation of this fault, thus, could enhance the further possibility of an earthquake in near future, and hence leading to devastating flood in the almost flat-lying downstream part of the Tirna River.

Measuring the Spatial Spillover Effects of Multimodel Transit System in Beijing: A Structural Spatial Vector Autoregressive Approach

Changes in local transit passenger flow may cause a spatial spillover effect across the involved regions and affect traffic patterns in other regions. To identify the affected areas and the traffic patterns, this study develops an enhanced spatial vector autoregressive (SpVAR) model to investigate relations in public transport systems in the case of sudden large passenger flow impact. The proposed model captures the interacted correlation within different transit models in separated regions. Three representative commuting regions in Beijing, namely, Zhongguancun, Guomao, and Huilongguan, are employed for empirical study. Results confirm the existence of spatial spillover effect in the commuter regions and reveal heterogeneous effects of multimodal transit system on regions with different distances.

Sound generation by entropy perturbations passing through a sudden flow expansion

Abstract

Effect of vertical effective and initial static shear stresses on the liquefaction resistance of sands in cyclic direct simple shear tests

To investigate the effect of the vertical effective and initial static shear stresses on cyclic resistance under cyclic loading with principal stress rotation, a series of cyclic direct simple shear tests were conducted on loose and dense Nakdong River sands. The results revealed that the increasing vertical effective stress (σ′v0) often decreased the cyclic resistance, and the decrease was more evident for a high initial static shear ratio (α = 0.2). The degree of reduction of the correction factor Kσ predicted by recommended methods in practice mostly showed more conservative results than the measured Kσ values in this study. Increasing the initial static shear stress decreased the cyclic resistance of the loose sand. For the dense sand, the cyclic resistance either increased or decreased, depending on the combined effect of the σ′v0 and α levels. The correction factor Kα decreased minimally to 0.689 for the loose sand and rose maximally to 1.175 for the dense sand. When the relative density (Dr) increased from 40% to 80%, the increase in the cyclic resistance for a high α (=0.2) was considerably greater than that for α = 0. The cyclic response of the loose sand was due to sudden flow deformation without any apparent shear strain accumulation, regardless of the α value; while the cyclic response of the dense sand indicated plastic strain accumulation. Thus, the cyclic resistance of sand is influenced by the combined effect of Dr, σ′v0, and α, with the potential influence of principal stress rotation.

급격한 자본 흐름에 영향을 미치는 요인 분석과 시사점

본 연구에서는 통화정책이 자본 흐름에 영향을 주는 요인에 대해 분석하고자 하였다. 한국은행의 통화정책 결정에 있어 내외 금리차 축소와 외국인의 자금 유출 우려는 매번 금리 인하를 제약하는 요인으로 작용하고 있다. 하지만, 2000년 이후 한국과 미국의 정책금리 역전이 세 차례 정도 나타났지만 외국인의 급격한 자본 유출은 발생하지 않았다. 이는 내외 금리차가 외국인의 자본 유출에 주요 변수가 아닐 수 있음을 시사한다. 이에 본 연구에서는 급격한 자본 이동, 그 중 외국인 자본 유출이 급격하게 나타날 때 영향을 미치는 주요 결정 요인을 실증적으로 검증하였다. 실증 분석 결과, 외국인의 급격한 자금 유출은 국내 요인보다 대외 불안요인에 더 민감하게 반응했으며 금리차보다 자국의 성장이 중요하게 작용하였다. 이는 통화정책의 변화가 자본 유출입의 직접적인 요인은 아니며 이를 감안할 때 향후 한국은행의 통화정책 결정에 있어 자본 유출 우려보다 성장에 맞춘 정책을 보다 고려할 필요가 있음을 시사한다.

Application of Model Predictive Control for Large-Scale Inverted Siphon in Water Distribution System in the Case of Emergency Operation

The emergency control of Menglou~Qifang inverted siphon, which is about 72 km long, is the key to the safety of the Northern Hubei Water Transfer Project. Given the complicated layout of this project, traditional emergency control method has been challenged with the fast hydraulic transient characteristics of pressurized flow. This paper describes the application of model predictive control (MPC), a popular automatic control algorithm advanced in explicitly accounting for various constraints and optimizing control operation, in emergency condition. For the fast prediction to the pipe-canal combination system, a linear model for large-scale inverted siphon proposed by the latest research and the integrator-delay (ID) model for open canals are used. Simulation results show that the proposed MPC algorithm has promising performance on guaranteeing the safety of the project when there are sudden flow obstruction incidents of varying degrees downstream. Compared with control groups, the peak pressure can be reduced by 17.2 m by MPC under the most critical scenario, albeit with more complicated gates operations and more water release (up to 9.75 × 104 m3). Based on the linear model for long inverted siphon, this work highlights the applicability of MPC in the emergency control of large-scale pipe-canal combination system.

Epidemiological and clinical analysis of the outbreak of dengue fever in Zhangshu City, Jiangxi Province, in 2019.

This study analyzed the epidemiological and clinical features of dengue fever in Zhangshu, Jiangxi Province, in 2019 and provided evidence for the diagnosis, treatment, prevention, and control of dengue fever. A total of 718 dengue fever patients in Zhangshu in 2019 were involved. ELISA and qRT-PCR were used for pathogenic detection of dengue virus. Multiple adjuvant therapies were applied, and the condition of patients after treatment was examined. Patients were between the ages of 0.75 and 92 years old, and all of them had a fever. A total of 519 cases had fatigue, and 413 cases had generalized myalgia and bone ache; 356 cases had dry mouth, 289 cases had bitter taste, and 167 cases felt dry and bitter taste; 279 cases had rash, and 93 cases had pruritus; 587 cases had decreased leukocyte, among which, 7 cases had leukocyte lower than 1 × 10 [9]/L; 380 cases had a low platelet count, and the platelet count of 29 cases was lower than 50 × 10 [9]/L; 488 cases had increased aspartic transaminase, and 460 cases had increased alanine aminotransferase; 5 cases had a severe disease. It proved that the majority of dengue fever sufferers were adults, with the main clinical features being fever and rash and the chief injured organs being the blood system, liver, heart, and gastrointestinal tract. Besides, over 40% of patients had dry and bitter taste, and 12 cases had alopecia after discharge. It indicates that the incidence of dengue fever in Zhangshu is closely related to the sudden population flow and imported cases.

Hospital reengineering against COVID-19 outbreak: 1-month experience of an Italian tertiary care center.

The recent outbreak of SARS-CoV-2 infection in Italy has resulted in a sudden and massive flow of patients into emergency rooms, and a high number of hospitalizations with the need for respiratory isolation. Massive admission of patients to the Policlinico "Agostino Gemelli" Foundation of Rome, Italy, determined the need for reengineering the entire hospital. In this article, we consider some of the structural and organizational changes that have been necessary to deal with the emergency, with particular reference to non-intensive medicine wards, and the preventive measures aimed at limiting the spread of SARS-CoV-2 infection among hospital staff and patients themselves. 577 staff members were subjected to molecular tests in 1-month period and 3.8% of the total were positive. 636 patients admitted to the COVID-19 pathway were included and analyzed: 45.4% were identified as SARS-CoV-2 positive. More SARS-CoV-2 negative patients were discharged in comparison to SARS-CoV-2 positive patients (59% vs. 41%, respectively). On the other hand, more SARS-CoV-2 positive patients were transferred to ICUs in comparison to SARS-CoV-2 negative patients (16% vs. 1%, respectively). Occurrence of death was similar between the two groups, 11% vs. 7%, for SARS-CoV-2 negative and positive patients, respectively. 25% of ≥80 years old SARS-CoV-2 positive patients died during the hospitalization, while death rate was lower in other age groups (5% in 70-79 years old patients and 0% in remaining age groups). Rapid hospital reengineering has probably had an impact on the management of patients with and without SARS-CoV-2 infection, and on in-hospital mortality rates over the reporting period.

Influence of hydropower outflow characteristics on riverbank stability: case of the lower Osage River (Missouri, USA)

ABSTRACT This research examined the influences of outflow characteristics affecting riverbank stability. The 130-km stretch of the Lower Osage River downstream from Bagnell Dam (Missouri, USA) provided an excellent case study for this purpose. The integrated BSTEM model with the HEC-RAS model was accurately calibrated and validated with data from the US Geological Survey. Then, the outflow characteristics (peak flow duration, flow drawdown rate, and low flow duration) were investigated individually. The results of this study showed that: (1) riverbank stability is little affected by the duration time of the peak flow, especially on the reaches far from the dam; (2) sudden flow drawdown significantly reduces riverbank stability; however, the impact of the drawdown rate decreases with distance from the dam; and (3) the duration of the low flow after peak flow influences the riverbank stability value proportional to the distance from the dam. The time of low flow before failure increases as the distance from the dam increases.

An LSTM-Based Method Considering History and Real-Time Data for Passenger Flow Prediction

With the development of big data and deep learning, bus passenger flow prediction considering real-time data becomes possible. Real-time traffic flow prediction helps to grasp real-time passenger flow dynamics, provide early warning for a sudden passenger flow and data support for real-time bus plan changes, and improve the stability of urban transportation systems. To solve the problem of passenger flow prediction considering real-time data, this paper proposes a novel passenger flow prediction network model based on long short-term memory (LSTM) networks. The model includes four parts: feature extraction based on Xgboost model, information coding based on historical data, information coding based on real-time data, and decoding based on a multi-layer neural network. In the feature extraction part, the data dimension is increased by fusing bus data and points of interest to improve the number of parameters and model accuracy. In the historical information coding part, we use the date as the index in the LSTM structure to encode historical data and provide relevant information for prediction; in the real-time data coding part, the daily half-hour time interval is used as the index to encode real-time data and provide real-time prediction information; in the decoding part, the passenger flow data for the next two 30 min interval outputs by decoding all the information. To our best knowledge, it is the first time to real-time information has been taken into consideration in passenger flow prediction based on LSTM. The proposed model can achieve better accuracy compared to the LSTM and other baseline methods.

A Review on Applications of Particle Image Velocimetry

Fluid dynamic field is frequently classified and designated into two which are hydrodynamics and aerodynamics. Particle Image Velocimetry (PIV) has been exerted to many flow problems in a broad range. PIV application to the measurement of velocity distributions in fluid flow is represented by the Stokes number. PIV can be executed to practically for any sort of flow if the fluid is transparent to allow suspended particles image. The purpose of this paper is to present some examples of application of PIV in general cases. In the midst of numerous applications of PIV, turbulent flows are the most comprehensively demanding because of their three-dimensionality, naturally large ranges of length and unsteadiness. Sudden flow field measurements of PIV method can be applied for the demotion of turbulence quantities and mean velocities.