Dangerous Regions Research Articles

Virtual Reality Visualization of CFD Simulated Blood Flow in Cerebral Aneurysms Treated with Flow Diverter Stents

Virtual reality (VR) has the potential to be a powerful tool for the visualization of simulated blood flow in cerebral aneurysms. This paper presents our study aimed at developing the VR visualization of computational fluid dynamics (CFD) simulations of cerebral aneurysms treated with flow-diverting (FD) stents. First, a spherical sidewall aneurysm located at a simplified internal carotid artery was considered for investigating the impact of stent deployment and positioning on the corresponding spatially time-varying blood flow behavior. The three-dimensional unsteady blood flow over a cardiac cycle was simulated numerically using the finite volume method, and the distributions of hemodynamic parameters inside the aneurysm sac, and on its wall, were presented with and without stent cases. Two stent positions, with and without a gap between the artery wall and stent, were considered to show the influence of correct stent position on aneurysm treatment. Second, a straightforward workflow was developed to import, process, and visualize the CFD analysis data in a VR environment by using open-source software with a high resolution. The Unity3D engine was used for displaying the processed animations in a VR environment operated on a head-mounted display (HMD). The refining process of each frame of time-varying CFD data was automated. The animated flow elements rendered in the VR environment were velocity vectors, velocity contours, streamlines, particle traces, and point clouds. CFD results showed that proper stenting facilitates thrombosis and occlusion of the aneurysm by modification of the flow patterns, which leads to lower inflow jet velocities into the aneurysm, longer turnover time, lower aneurysm-averaged kinetic energy, and lower wall shear stress. Additionally, the results indicated that a gap between the stent and the parent artery may lead to undesirable hemodynamic alterations. The VR visualization illustrated that the recognition of the potential in danger regions of aneurysms and the evaluation of the performance of FD stents in aneurysm treatment can be conducted without the need for several slices through the parent artery and aneurysm, as is required for traditional postprocessing methods. Through VR visualization, the details of the simulation results become readily available by navigating in the 3D animated flow elements using a high-degree-of-freedom headset.

Seismic behaviors of free-spanning submarine pipelines subjected to multi-support earthquake motions within offshore sites

Due to the shortage of offshore seismic records and inhere difficulty in simulating artificial offshore ground motions, numerous existing works have been performed to investigate the seismic responses of free-spanning submarine pipelines, not only using onshore seismic records as inputs but also adopting uniform seismic excitations. These analytical schemes may result in severe misestimates of the seismic responses. In this content, this paper numerically investigates the seismic behaviors of a free-spanning submarine pipeline by using multi-support earthquake motions within offshore sites (MEMOSs) as inputs. The soil-pipe and water-pipe interactions are modeled using the nonlinear soil spring and added mass methods, respectively. The effects of spatially varying and overlying seawater are explicitly taken into account in the simulation of MEMOSs. The seismic behavior law of the free-spanning submarine pipeline under the synthesized MEMOSs is analyzed and summarized. Moreover, the impacts of the seismic excitation type, offshore seismic motion, coherence loss, local site condition and free span length on the Mises stress, vertical displacement and failure PGA of the submarine pipeline are examined and discussed comprehensively. Numerical results show that the middle and ends of free span are the dangerous regions; and the MEMOSs, coherence loss, local site condition and free span length have significant influences on the seismic responses and operational capacity of the pipeline. Based on the obtained results, some meaningful advices are recommended to the pipeline designers that (1) more attentions should be paid to the middle and ends of free span in the pipeline design; (2) the MEMOSs should be adopted as seismic inputs to accurately predict the seismic behaviors of pipelines; (3) the construction of submarine pipelines in soft clay and formation of large-dimensional free span are adverse for the safe operation of pipelines under earthquake actions, which should be avoided in engineering practice.

Spatial Memory in a Spiking Neural Network with Robot Embodiment.

Cognitive maps and spatial memory are fundamental paradigms of brain functioning. Here, we present a spiking neural network (SNN) capable of generating an internal representation of the external environment and implementing spatial memory. The SNN initially has a non-specific architecture, which is then shaped by Hebbian-type synaptic plasticity. The network receives stimuli at specific loci, while the memory retrieval operates as a functional SNN response in the form of population bursts. The SNN function is explored through its embodiment in a robot moving in an arena with safe and dangerous zones. We propose a measure of the global network memory using the synaptic vector field approach to validate results and calculate information characteristics, including learning curves. We show that after training, the SNN can effectively control the robot’s cognitive behavior, allowing it to avoid dangerous regions in the arena. However, the learning is not perfect. The robot eventually visits dangerous areas. Such behavior, also observed in animals, enables relearning in time-evolving environments. If a dangerous zone moves into another place, the SNN remaps positive and negative areas, allowing escaping the catastrophic interference phenomenon known for some AI architectures. Thus, the robot adapts to changing world.

Evaluation and Spatial Analysis of Road Accidents in Bangladesh: an Emerging and Alarming Issue

Around 1.2 million people are being killed, and more than 50 million people are being injured in road accidents each year around the world. Due to Urbanization and motorization road accident has been increasing dramatically over the last few years. According to the Accident Research Institute (ARI) of BUET, on an average, 20 people are dying every day in Bangladesh. Reckless driving, overloading identified as a significant causes for road accidents. Moreover, motorbikes has a higher number of accidents in Bangladesh. The main objective is to identify the leading causes of road accidents and the spatial distribution of road accidents. The data of accidents were collected from different secondary sources for the last 50 years. Qualitative and semi quantitate methods were used to analyze the statistical data. For spatial distribution of road accidents, the kernel density estimation method is used as well as critical area index for hazardous locations. The critical area index has presented from crash rate and causality rate of the zone as a dangerous area with the score (1–10) where highs score represents the most dangerous region for road accidents. The traffic department and the Government has a crucial role to play in identifying reckless driving, speeding and overloaded vehicles, and the government and citizens have an essential role to play in ensuring road safety as well.

Adaptive multi-scale beam lattice method for competitive trans-scale crack growth simulation of heterogeneous concrete-like materials

In order to overcome the shortcomings of traditional pure macro- and meso-scale crack growth simulation method, here an adaptive multi-scale beam lattice method (AMBLM) is developed to simulate trans-scale crack growth process from meso-scale to macro-scale for quasi-brittle heterogeneous concrete-like materials with low computation cost. In the trans-scale crack growth simulation, dangerous regions can be automatically found and the meso-scale model is then re-modeled in the found region, which can ensure continuous changes in the adaptive multi-scale modeling due to cracking. In this way, the meso-scale simulation is only implemented in the dangerous region of crack growth paths, and macro-scale simulation is implemented in other regions. This can improve computational efficiency of the developed method significantly. In order to verify the developed AMBLM, the trans-scale crack growth process of two concrete specimens are simulated. Then the simulation results are compared with experimental results, which show that the developed AMBLM is effective. In addition, the simulation results are also compared with the computation results obtained from pure meso-scale simulation. The results show that AMBLM has very high precision and superior computational efficiency on multi-scale crack growth simulation of quasi-brittle concrete-like materials.

A tengerek biztonságáról, különös tekintettel a Guineai-öböl térségére

A tengeri közlekedés és szállítás biztonsága – különösen Afrika viszonylatában – látszólag távol eshet a magyar közérdeklődéstől, valamint a rend- és honvédelmi szervezetek mindennapos feladataitól. A déli iránnyal is bíró nemzeti kül- és külgazdasági politika, illetve Magyarország NATO- és EU-tagsága miatt is azonban immár szélesebb keretben kell biztonságunkat értékelni. Az interdependencia és a globalizáció korában a földrajzilag távoli térségekben zajló folyamatokat is érdemes figyelemmel kísérni és elemezni, hogy időben adekvát válaszlépések születhessenek, ha szükséges. A Guineai-öböl az elmúlt években a legveszélyesebb területté vált a kalózkodás szempontjából, de a szervezett bűnözői tevékenység és kábítószer-csempészet mértéke és társadalmi beágyazottsága is aggasztó – mivel összefüggenek és táplálják a Nigériában és a Száhel övezetben működő, az itteni államok működőképességét aláásó szélsőséges szervezetek harcát. A Maliban növekvő szerepet vállaló Magyar Honvédség szempontjából sem mellékes, hogy ezek a csoportok a forrásaiktól elszigetelődjenek, marginalizálódjanak, ezzel pedig a tartós rendezéshez szükséges biztonsági feltételek megteremtődjenek.

Comparison of Local Recurrence Patterns of Postoperative Radiotherapy with Surgery Alone for Esophageal Carcinoma Patients

ABSTRACT Background: We analyzed local regional recurrence patterns of thoracic esophageal carcinoma after three-field lymph node dissection (3-FLD) with and without postoperative radiotherapy, and assessed the postoperative radiation value for local control. Methods: The study reviewed 239 local recurrences of esophageal squamous cell carcinoma after 3-FLD from 2010 to 2018 in our hospital, retrospectively, and compared local regional recurrence patterns between surgery followed by radiotherapy (S+RT) and surgery alone (SA). Results: In 239 thoracic esophageal carcinomas that underwent curative surgery, the lymph node recurrence was the most common type of local recurrence for patients in both groups. The sequence of lymph node recurrence rate in both groups from highest to lowest was mediastinal, cervical, and abdominal. The recurrence rate of superior mediastinal lymph node in patients without radiotherapy was significantly higher than that in patients with radiotherapy (67.72% vs. 47.54%, x2 = 7.615, P = 0.006). The recurrence rate of abdominal lymph node in the upper TEC was significantly lower than that in the middle and lower TEC (x2 = 9.452, P = 0.009). The abdominal lymph node recurrence rate in patients with preoperative abdominal LNM was very significantly higher than that in patients without preoperative abdominal LNM (43.63% vs. 6.66%, P < 0.001). Conclusions: The dangerous lymph node recurrence regions included superior, middle mediastinum, and neck. Postoperative radiotherapy shows great value for patients in reducing superior mediastinal lymph node recurrence rate. The lower segment of thoracic esophageal carcinoma and preoperative abdominal lymph node metastasis, especially para-aortic lymph node metastasis, may be risk factors for abdominal lymph node recurrence.

ОПРЕДЕЛЕНИЕ ОПТИМАЛЬНЫХ ПАРАМЕТРОВ ДЕМПФИРОВАНИЯ ЗЕМЛЯНОГО ПОЛОТНА ЖЕЛЕЗНЫХ ДОРОГ В СЕЙСМИЧЕСКИ АКТИВНЫХ РАЙОНАХ

The paper considers a damping layer design for roadbed with parameters that provide safety of railway traffic in seismically dangerous regions. It presents a theoretical study of seismic forces on railway roadbed on the basis of analysis of earthquake influence parameters on stressed and strained state of railway track construction. For the investigations the author has applied methods of multifactorial experimental design. The author has developed a method for determination of optimal parameters for damping depending on main parameters of an earthquake (magnitude, distance from hypocenter, physical and mechanical characteristics of the Earth crust) and geological characteristics of a railway section (capability of layers, deformational and elastic properties of the Earth crust, foundation and roadbed). As a result, the author suggests designs of a damping layer that has a layered-geterogenous compositional structure with given properties. Moreover, he has established a possibility to increase an aseismic stability of railway roadbed by construction of the damping layer with given properties.

Earthquake Performance Analysis of Existing Reinforced Concrete Structure in the Istanbul Metropolitan Area Using Non-Linear Method

Many people suffer loss of life and property due to the earthquake disaster in Turkey. In order to minimize this disaster, the resistance of the structures to earthquake should be determined under the light of studies done before. Turkey is in one of the most dangerous seismic regions in the World. As a sub plate between the large Eurasian, Arabian and African plates, Turkey rests on the Anatolian tectonic plate. Arabian plate in the direction of pushing Turkey to the North, the Anatolian plate moves in the opposite clockwise. However, it is prevented to move in the North direction due to the Eurasian plate. In this case, it contains many active faults and Turkey’s most populous city of Istanbul is in danger. In this study, it is aimed to perform a performance analysis according to the Turkey Building Earthquake Code 2018 in a six-story reinforced concrete shear wall-framed structure in Istanbul where active fault lines are located. This existing complex designed reinforced concrete building investigated in this study is in the city of ?stanbul, Turkey. This city is under danger of approaching and inevitable Great Istanbul Earthquake likely greater than Mw 7. The nonlinear seismic behavior of a complex reinforced concrete (RC) residential building is investigated by and linear and the static pushover. The selected reinforced concrete structure was designed according to 1998 version of Turkish Earthquake Code (TEC-1998). In the earthquake engineering, performance-based design method is used to determine the level of expected performance of the structures under the earthquake effect. According to the code, the reinforced concrete shear wall building is not expected to satisfy controlled damage (life safety) performance levels under design earthquake

Deformation of Corset-Shaped Specimens during Cyclic Heating

The deformation that develops in a corset specimen during its cyclic heating is analyzed. The plastic deformation in the central part of the specimen, where usually fracture is localized, reaches a very large value of 6–7% (for the thermal conditions typical of thermal fatigue research). This is explained by mechanical deformation due to external cyclically compressed and expanded specimen shoulders, which are rigidly constrained only from the heads. A thermocyclic diagram for a flat corset specimen is given; it differs significantly from the diagram for specimens with a long gauge part (for example, the Coffin technique). Corset specimens are recommended for full-scale tests of products by changing their shape (modeling dangerous regions of the products) and plastic deformation in a wide range.

Atypical location of Coumel Tachycardia in Adult: Case Report

Coumel Tachycardia or Incessant Junctional Reentrant (IJRT) generally affects the infant-juvenile population and is characterized by tachycardia due to atrioventricular reentry (AV) mediated by an exclusive, slow, decremental retrograde conduction pathway mostly located in the posterosseptal region of the tricuspid ring. Case report: The present study reported the case of an adult, 49 years old, with IJRT of atypical location. The patient reported feeling palpitations for 5 years with worsening in the last 6 months. After one of his seizures, an electrocardiogram (ECG) documented tachycardia due to AV reentry with a long RP ‘interval. Subjected to an electrophysiological study, an accessory pathway of exclusive retrograde conduction with decreasing characteristics was observed, located in the right mid-septal region. There was easy induction of IJRT, remaining sustained throughout the study. A radiofrequency ablation was performed in the mid-septal D region with interruption of tachycardia, with no more atrioventricular retrograde conduction, the procedure ended without complications. Discussion: Interestingly, the case described differs both in terms of the age range of the most frequent involvement of the IJRT (children and young people), as well as the most common location of the accessory pathway (posterior and postero-septal region of the tricuspid ring). Ablation proved to be effective in this case and is the treatment of choice for IJRT despite the anomalous location of the accessory pathway (Middle-septal D: described in bibliographic reviews in only 7% of IJRT cases) and a potentially dangerous region due to proximity to the trunk of the His beam.

The Simulation of Aircraft Ditching Based on ALE Method

Ditching is an emergency measure for landing on the water when the aircraft cannot continue to fly in an accident. In order to verify the performance of the aircraft ditching, this paper carry out a simulation study on ditching of fixed-wing aircraft on the water. First determine the simulation method, material model and constitutive equation, and then analyze the influence of the sinking speed and attitude changes on the ditching of the aircraft. The simulation method adopts arbitrary Lagrange-Euler method (ALE). The results show that as the sinking speed increases, the load will increase accordingly. As the initial attitude angle increases, the vertical acceleration gradually decreases, and the longitudinal acceleration is basically the same, the pressure acting area gradually moves backward, and the pressure area gradually decreases. It is necessary to take appropriate local strengthening measures on the dangerous region.

Controlling the parametric roll of a container ship model by changing the forward velocity

Parametric roll on ships is a resonance phenomenon whose onset causes heavy roll oscillations leading to dangerous situations for the ship, the cargo and the crew. It affects both small vessels with marginal stability and large container ships if four conditions are met simultaneously: the wave length and ship length are approximately equal, the frequency of encounter wave is twice the roll natural frequency, the ship’s roll damping is low enough and the wave height exceeds a limit value characteristic to each vessel. A good start to capture the basic features of the parametric roll is to cancel the couplings between roll and the other motions of the ship and to analyse the influence of parameters on the ship stability and the appearance of large roll amplitudes by using one-degree-of-freedom model. By doing this, one realizes that, besides increasing the damping, the roll motion can be stabilized by changing the wave encounter frequency in such a way that the resonance condition is no longer fulfilled. Two parameters mainly affect the encounter frequency: the ship forward velocity and the heading angle. In the paper, we have numerically investigated the effect of increasing or decreasing the forward speed on the roll amplitudes. We followed two strategies. In the first, we allowed the speed to change with a constant acceleration (positive or negative) so that the encounter frequency has left the dangerous region of the resonance. In the second strategy, we changed the forward speed up and down around a value that generates large roll amplitudes, by using different periodic profiles such as sinusoidal, saw tooth or trapezoidal. We noticed that both control techniques generally managed to significantly reduce the roll amplitudes (with a few exceptions). At the same time, we found that very important in how the amplitudes diminish are parameters like the moment of time when the control is activated, the speed rate of change or the period and amplitude of the speed change around the average value (in the second strategy). The data used in the paper have been obtained from experiments with a container ship model in a towing tank followed by expansion to a full scale ship.

Autonomous staircase climbing robot for rescue application

This paper discusses the construction and application of an autonomous staircase climbing robot. Such a robot has several applications in real life. It can be used in dangerous regions for surveillance, rescue, and exploration with the help of a camera placed on it or by carrying resources. After going through various research papers a concept of such a robot was visioned. Following which design was formulated and simulations were carried out. A prototype was fabricated with mechanical and electrical parts. It is a simple climbing robot with two rods as support at the front. A simple rack and pinion gear are used to lift the robot while climbing. An ultrasonic sensor is placed at the front to sense the width and height of the stairs. Various testing and analysis have been done on the prototype to eliminate all drawbacks. The robot has shown to successfully climb the stairs.

Numerical prediction of thermal insulation performance and stress distribution of thermal barrier coatings coated on a turbine vane

Understanding the thermal insulation performance and thermal stress of thermal barrier coating (TBC) coupled with internal cooling and film cooling plays a key role in designing and predicting the failure of TBC. In this work, A one-dimensional theoretical model is presented to analyze the trends of performance of TBC with respect to various parameters. Based on the fluid-solid coupling method, a three-dimensional (3D) finite element model of a guide vane coated with TBC is performed to evaluate the thermal insulation effectiveness and thermal stress of TBC. Furthermore, the effect of film hole geometries on the thermal insulation performance and thermal stress distribution of TBC are investigated. It is found the thermal insulation effectiveness decreases with the increase of film cooling effectiveness but increases with external/internal convective heat transfer coefficients. According to the thermal stress results, the dangerous regions of TBCs are predicted. Stress concentration occurs at the upstream position of film hole. Compared with the round and fan holes, the thermal stress of TBC with trench hole is lowest. Comprehensive consideration the thermal insulation performance and stress distribution of TBC with different film hole geometries, the trench hole is a better design for a longtime service of TBC.

Development of pulse mechanical seal calculation methods on the basis of its physical model construction

A physical model was constructed for a pulse mechanical seal as a system for automatically controlling the end clearance. The effect of pulse compaction parameters on static characteristics was studied. The analysis of static characteristics revealed the influence of the design parameters of pulse compaction on the size of the end clearance and the flow rate of the fluid being sealed. Conclusions were made about the influence of the load factor and the efforts of the preliminary compression of the springs on the static characteristics of pulse compaction. The static calculation helped determine the coefficient of hydrostatic stiffness, the condition of static stability, and the range of permissible sealing pressures. The factors affecting the dynamic characteristics of the seal were determined. Dimensional values of the amplitudes of the forced axial vibrations of the ring were estimated at any rotation frequency. Expressions of the amplitude and phase frequency characteristics were obtained, which made it possible to identify dangerous regions of rotational frequencies and select the sealing parameters so that the amplitudes of the forced axial vibrations of the ring could not go beyond the limits of dynamic stability. It was revealed that the stability region expands due to a decrease in the volume of the chambers and a decrease in the coefficient of hydrostatic stiffness. A method for the analytical calculation of pulse mechanical seals was proposed to make it possible to calculate the geometry of the seal at the design stage. The study offers an example of engineering calculations for a pulse mechanical seal as well as the design of a sealing assembly developed by the proposed method

Extended Fundamental Diagrams

By using a large data-base of single vehicle data from a German freeway, the fundamental diagram (FD) can be extended. These types of data allow extraction of additional information that can be displayed as a function of the traffic flow [Formula: see text] and speed [Formula: see text]. This is demonstrated here with a surrogate measure of safety (SMoS) and two other indices, which can be used to perform more in-depth analyses of traffic flow. In the case of the SMoS, it is possible to identify more and less dangerous regions in the extended FD.

Infesting our country: discursive illusions in anti-immigration border talk

ABSTRACTThis paper investigates how, despite the need to flee dangerous regions, online and print newspapers rely on negative portrayals of migrants and immigrants to forward nationalist positions, including the belief that so-called foreigners are a threat to the security and economic well-being of a nation. Specifically, using the Discourse of Illusion as our main analytic framework, the analysis demonstrates the ways in which dehumanization is central to forwarding ideological positions against migration. Our findings are then used to discuss larger issues of how media is transforming the ways in which political ideologies are constructed and circulated.

Land Subsidence Related to Coal Mining in China Revealed by L-band InSAR Analysis.

Geological disasters, including ground deformation, fractures and collapse, are serious problems in coal mining regions, which have threatened the sustainable development for local industry. The Ordos Basin is most known for its abundant coal resources. Over-mining the underground coal resources had induced land deformation. Detecting the evolution of the land deformation features and identifying the potential risk are important for decision-makers to prevent geological disasters. We analyzed land subsidence induced by coal mining in a 200 area in the Ordos Basin for the time period 2006–2015. ALOS-1 PALSAR images from December 2006 to January 2011 and ALOS-2 PALSAR-2 images from December 2014 to July 2015, optical remotely sensed images and coal mining information were collected. The small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) method and differential interferometric synthetic aperture radar (D-InSAR) method, GIS and statistical analysis were adopted. Results show that the maximum subsidence rate and cumulative subsidence along the line of sight (LOS) were −65 mm/year and −246 mm, respectively, from December 2006 to January 2011. The maximum cumulative subsidence was −226 mm from December 2014 to July 2015. The new boundary of the mining goafs from 2014 to 2015 and the most dangerous risk region were mapped. Moreover, the effect of large-scale mining coal, with the production volume exceeds 1.2 million tons per year, with the operation time more than 20 years on land subsidence was found greater than small and medium-scale coal mines and reached −59 mm/year. The recently established small-sized and medium-sized coal mines show high land subsidence. This study will contribute to better understand the land subsidence process in mining region and provide scientific support for government to prevent land subsidence.

Understanding Trauma for Reconciliation and Peace-building Journalism in Colombia

ABSTRACT This study argues that a better understanding of trauma can support a journalism that seeks to build peace in Colombia. Based on a participant observation, it presents the experiences of four local journalists living and working in a context of protracted violence in one of the country’s most dangerous regions. Through an application of Newman and Nelson’s conceptual framework of the three tensions or “dances” of trauma, it is argued that an ethical and trauma-aware practice can underpin a more inclusive narrative of peace and conflict. An emotionally literate journalism, which seeks out the voices and experiences of the marginalised, has the potential to promote social cohesion in the aftermath of suffering and pave the foundations for reconciliation within a community. This people-focused approach strengthens resilience in both the reporter and the reported by equipping local journalists with the skills and knowledge they need to live up to the contemporary expectations of peace-building that have been placed upon them.