Search results for: temporal displacement

Authors: Manuel A. Guzman, Davide Forcellini, Ricardo Moreno, Diego H. Giraldo

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Elastomeric bearings (EB) are used in many applications, such as base isolation of bridges, seismic protection and vibration control of other structures and machinery. Their versatility is due to their particular behavior since they have different stiffness in the vertical and horizontal directions, allowing to sustain vertical loads and at the same time horizontal displacements. Therefore, vertical, horizontal and bending stiffnesses are important parameters to take into account in the design of EB. In order to acquire a proper design methodology of EB all three, theoretical, finite element analysis and experimental, approaches should be taken into account to assess stability due to different loading states, predict their behavior and consequently their effects on the dynamic response of structures, and understand complex behavior and properties of rubber-like materials respectively. In particular, the recent large-displacement theory on the stability of EB formulated by Forcellini and Kelly is validated with both numerical simulations using the finite element method, and experimental results set at the University of Antioquia in Medellin, Colombia. In this regard, this study reproduces the behavior of EB under compression loads and investigates the stability behavior with the three mentioned points of view.

Keywords: elastomeric bearings, experimental tests, numerical simulations, stability, large-displacement theory

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Authors: Mawa Abdelbagi Mohamed Mohamed, Eslam Alaa Elbahlawan

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This study examines the complex social fabric woven within the Abu-Shouk internally displaced persons camp, shaped by the chaotic waves of armed conflict and displacement in the early 2000s. The impact of war, economic constraints, and altered living conditions have fundamentally reshaped families and traditions, presenting both challenges and opportunities. In this exploration, we navigate the resilience of a community thrust into adversity, spotlighting how it emerged as essential in rebuilding social bonds. Exchanges of culture, intertribal marriages, and communal gathering spots have become essential tools in fostering cohesion and understanding amidst diversity. However, this resilience has been tested by the intrusion of politics, leading to shifts in governance structures and community dynamics. As we conclude, it is evident that while the scars of displacement and political disruptions are present, the community's enduring spirit and adaptability shine through. Empowering the community to rebuild their social tapestry, bridging the gaps, and restoring unity amid evolving political realities remain the beacon guiding their journey toward a shared, purposeful future.

Keywords: darfur, internally displaced person, social fabric, conflict

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Authors: Shield B. Lin, Ziraguen O. Williams

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In a task to assist NASA in analyzing the dynamic forces caused by operational countermeasures of an astronaut’s exercise platform impacting the spacecraft, an active proportional-integral-derivative controller commanding a linear actuator is proposed in a vibration isolation system to regulate the movement of the exercise platform. Computer simulation shows promising results that most exciter forces can be reduced or even eliminated. This paper emphasizes on parameter uncertainties, variations and exciter force variations. Drift and variations of system parameters in the vibration isolation system for astronaut’s exercise platform are analyzed. An active controlled scheme is applied with the goals to reduce the platform displacement and to minimize the force being transmitted to the spacecraft structure. The controller must be robust enough to accommodate the wide variations of system parameters and exciter forces. Computer simulation for the vibration isolation system was performed via MATLAB/Simulink and Trick. The simulation results demonstrate the achievement of force reduction with small platform displacement under wide ranges of variations in system parameters.

Keywords: control, counterweight, isolation, vibration

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Authors: Anastasiya Paltarzhitskaya

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Subjective time plays an important role in consciousness processes and self-awareness at the moment. The concept of intrinsic neural timescales (INT) explains the difference in perceiving various time intervals. The capacity to experience the present builds on the fundamental properties of temporal cognition. The challenge that both philosophy and neuroscience try to answer is how the brain differentiates the present from the past and future. In our work, we analyze papers which describe mechanisms involved in the perception of ‘present’ and ‘non-present’, i.e., future and past moments. Taking into account that we perceive time intervals even during rest or relaxation, we suppose that the default-mode network activity can code time features, including the present moment. We can compare some results of time perceptual studies, where brain activity was shown in states with different flows of time, including resting states and during “mental time travel”. According to the concept of mental traveling, we employ a range of scenarios which demand episodic memory. However, some papers show that the hippocampal region does not activate during time traveling. It is a controversial result that is further complicated by the phenomenological aspect that includes a holistic set of information about the individual’s past and future.

Keywords: temporal consciousness, time perception, memory, present

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Authors: Amine Ben Slama, Aymen Mouelhi, Sondes Manoubi, Chiraz Mbarek, Hedi Trabelsi, Mounir Sayadi, Farhat Fnaiech

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Vertigo is a sensation of feeling off balance; the cause of this symptom is very difficult to interpret and needs a complementary exam. Generally, vertigo is caused by an ear problem. Some of the most common causes include: benign paroxysmal positional vertigo (BPPV), Meniere's disease and vestibular neuritis (VN). In clinical practice, different tests of videonystagmographic (VNG) technique are used to detect the presence of vestibular neuritis (VN). The topographical diagnosis of this disease presents a large diversity in its characteristics that confirm a mixture of problems for usual etiological analysis methods. In this study, a vestibular neuritis analysis method is proposed with videonystagmography (VNG) applications using an estimation of pupil movements in the case of an uncontrolled motion to obtain an efficient and reliable diagnosis results. First, an estimation of the pupil displacement vectors using with Hough Transform (HT) is performed to approximate the location of pupil region. Then, temporal and frequency features are computed from the rotation angle variation of the pupil motion. Finally, optimized features are selected using Fisher criterion evaluation for discrimination and classification of the VN disease.Experimental results are analyzed using two categories: normal and pathologic. By classifying the reduced features using the Support Vector Machine (SVM), 94% is achieved as classification accuracy. Compared to recent studies, the proposed expert system is extremely helpful and highly effective to resolve the problem of VNG analysis and provide an accurate diagnostic for medical devices.

Keywords: nystagmus, vestibular neuritis, videonystagmographic system, VNG, Fisher criterion, support vector machine, SVM

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Authors: Denise Muro

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Conflict in Syria, producing over 11 million displaced persons, has incited global attention to displacement. Although neighboring countries have borne the largest part of the displacement burden, due to the influx of refugees into Europe, the so-called ‘refugee crisis’ is taking place on two fronts: Syria’s neighboring countries, with millions of refugees, and Europe, a destination goal for so many that European states face unprecedented challenges. With increasing attention to displacement, forcibly displaced persons are consistently portrayed as either un-agentic victims, or as dangerous free agents. Recognizing that these dominant portrayals involve discourses of power and inequality, this research investigates the extent to which this victim-agent dichotomy affects refugees and organizations that work closely with them during initial integration processes in Berlin, Germany. The research measures initial integration based on German policy measures regarding integration juxtaposed with the way refugees and those who work with them understand integration. Additionally, the study examines day-to-day interactions of refugees in Germany as a way to gauge social integration in a bottom-up approach. This study involved a discourse analysis of portrayals of refugees and participant observation and interviews with refugees and those who work closely with them, which took place during fieldwork in Berlin in the summer of 2016. Germany is unique regarding their migration history and lack of successful integration, in part due to the persistent refrain, ‘Wir sind kein einwanderungsland’ (‘We are not an immigration country’). Still, their accepted asylum seeker population has grown exponentially in the past few years. Findings suggest that the victim-agent dichotomy is present and impactful in the process of refugees entering and integrating into Germany. Integration is hindered due to refugees either being patronized or criminalized to such an extent that, despite being constantly told that they must integrate, they cannot become part of German society.

Keywords: discourse analysis, Germany, integration, refugee crisis

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Authors: Sohail Ahmad, Inayat Kaleem

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Federally Administered Tribal Area(FATA) of Pakistan is one of the most neglected regions in the world as far as development is concerned. It has been the hub of all sorts of illegal activities including militancy and export of terrorism. Therefore, it became inevitable for the government of Pakistan to take action against militants through military operations. Small and large scale military operations are being taken against the non-state actors in FATA with continuity. Over the years, hundreds of thousands have been displaced from the tribal areas of the country. Moreover, military operation Zarb-e-Azb has been launched in North Waziristan Agency in June 2014 to counter militancy across the Af-Pak border region. Though successful in curbing militancy, the operation has displaced around 0.5 million people from the area. Most of them opt to take shelter in the government installed shelter camps, some of them take refuge outside tent villages in the country while some of them prefer to cross into Afghanistan rather their own country Pakistan. This paper will evaluate how the influx of these internally displaced persons in the country is influencing the socio-economic situation of not only the displaced but of the hosting areas as well. Secondly, attention would be given to gauge the impact of such a huge number of displaced population on the law and order and security situation in the host areas.

Keywords: Af-Pak, federally administered tribal area, IDPs, internal displacement, Pakistan

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Authors: Zahra Ramezanpanah, Joachim Carvallo, Aurelien Rodriguez

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This paper aims to detect anomalies in streaming data using machine learning algorithms. In this regard, we designed two separate pipelines and evaluated the effectiveness of each separately. The first pipeline, based on supervised machine learning methods, consists of two phases. In the first phase, we trained several supervised models using the UNSW-NB15 data-set. We measured the efficiency of each using different performance metrics and selected the best model for the second phase. At the beginning of the second phase, we first, using Argus Server, sniffed a local area network. Several types of attacks were simulated and then sent the sniffed data to a running algorithm at short intervals. This algorithm can display the results of each packet of received data in real-time using the trained model. The second pipeline presented in this paper is based on unsupervised algorithms, in which a Temporal Graph Network (TGN) is used to monitor a local network. The TGN is trained to predict the probability of future states of the network based on its past behavior. Our contribution in this section is introducing an indicator to identify anomalies from these predicted probabilities.

Keywords: temporal graph network, anomaly detection, cyber security, IDS

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Authors: Leo Laine, Morgan Johansson

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To meet the civilizations future needs for safe living and low environmental footprint, the engineers designing the complex systems of tomorrow will need efficient ways to model and optimize these systems for their intended purpose. For example, a civil defence shelter and its subsystem components needs to withstand, e.g. airblast and ground shock from decided design level explosion which detonates with a certain distance from the structure. In addition, the complex civil defence shelter needs to have functioning air filter systems to protect from toxic gases and provide clean air, clean water, heat, and electricity needs to also be available through shock and vibration safe fixtures and connections. Similar complex building systems can be found in any concentrated living or office area. In this paper, the authors use a multidomain modelling language called Modelica to model a concrete wall as a single degree of freedom (SDOF) system with elastoplastic properties with the implemented option of plastic hardening. The elastoplastic model was developed and implemented in the open source tool OpenModelica. The simulation model was tested on the case with a transient equivalent reflected pressure time history representing an airblast from 100 kg TNT detonating 15 meters from the wall. The concrete wall is approximately regarded as a concrete strip of 1.0 m width. This load represents a realistic threat on any building in a city like area. The OpenModelica model results were compared with an Excel implementation of a SDOF model with an elastic-plastic spring using simple fixed timestep central difference solver. The structural displacement results agreed very well with each other when it comes to plastic displacement magnitude, elastic oscillation displacement, and response times.

Keywords: airblast from explosives, elastoplastic spring model, Modelica modelling language, SDOF, structural response of concrete structure

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Authors: Naif Albelwi, Alan Kwan, Yacine Rezgui

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Cities with rapid growth face tremendous challenges not only to provide services to meet this growth but also to assure that this growth occurs in a sustainable way. The consumption of material, energy, and water resources is inextricably linked to population growth with a unique impact in urban areas, especially in light of significant investments in infrastructure to support urban development. Urban Metabolism (UM) is becoming popular as it provides a framework accounting the mass and energy flows through a city. The objective of this study is to determine the energy and material flows of Riyadh, Saudi Arabia using locally generated data from 1996 and 2012 and analyzing the temporal trends of energy and material flows. Preliminary results show that while the population of Riyadh grew 90% since 1996, the input and output flows have increased at higher rate. Results also show increasing in energy mobile consumption from 61k TJ in 1996 to 157k TJ in 2012 which points to Riyadh’s inefficient urban form. The study findings highlight the importance to develop effective policies for improving the use of resources.

Keywords: energy and water consumption, sustainability, urban development, urban metabolism

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Authors: Rao Singh Priyanka, Jayangondaperumal R.

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The Himalayan active fault has the potential to generate great earthquakes in the future, posing a biggest existential threat to humans in the Himalayan and adjacent region. Quantitative evaluation of accumulated and released interseismic strain is crucial to assess the magnitude and spatio-temporal variability of future great earthquakes along the Himalayan arc. To mitigate the destruction and hazards associated with such earthquakes, it is important to understand their recurrence cycle. The eastern Himalayan and Indo-Burman plate boundary systems offers an oblique convergence across two orthogonal plate boundaries, resulting in a zone of distributed deformation both within and away from the plate boundary and clockwise rotation of fault-bounded blocks. This seismically active region has poorly documented historical archive of the past large earthquakes. Thus, paleoseismologicalstudies confirm the surface rupture evidences of the great continental earthquakes (Mw ≥ 8) along the Himalayan Frontal Thrust (HFT), which along with the Geodetic studies, collectively provide the crucial information to understand and assess the seismic potential. These investigations reveal the rupture of 3/4th of the HFT during great events since medieval time but with debatable opinions for the timing of events due to unclear evidences, ignorance of transverse segment boundaries, and lack of detail studies. Recent paleoseismological investigations in the eastern Himalaya and Mishmi ranges confirms the primary surface ruptures of the 1950 C.E. great earthquake (M>8). However, a seismic gap exists between the 1714 C.E. and 1950 C.E. Assam earthquakes that did not slip since 1697 C.E. event. Unlike the latest large blind 2015 Gorkha earthquake (Mw 7.8), the 1950 C.E. event is not triggered by a large event of 1947 C.E. that occurred near the western edge of the great upper Assam event. Moreover, the western segment of the eastern Himalayadid not witness any surface breaking earthquake along the HFT for over the past 300 yr. The frontal fault excavations reveal that during the 1950 earthquake, ~3.1-m-high scarp along the HFT was formed due to the co-seismic slip of 5.5 ± 0.7 m at Pasighat in the Eastern Himalaya and a 10-m-high-scarp at a Kamlang Nagar along the Mishmi Thrust in the Eastern Himalayan Syntaxis is an outcome of a dip-slip displacement of 24.6 ± 4.6 m along a 25 ± 5°E dipping fault. This event has ruptured along the two orthogonal fault systems in the form of oblique thrust fault mechanism. Approx. 130 km west of Pasighat site, the Himebasti village has witnessed two earthquakes, the historical 1697 Sadiya earthquake, and the 1950 event, with a cumulative dip-slip displacement of 15.32 ± 4.69 m. At Niglok site, Arunachal Pradesh, a cumulative slip of ~12.82 m during at least three events since pre 19585 B.P. has produced ~6.2-m high scarp while the youngest scarp of ~2.4-m height has been produced during 1697 C.E. The site preserves two deformational events along the eastern HFT, providing an idea of last serial ruptures at an interval of ~850 yearswhile the successive surface rupturing earthquakes lacks in the Mishmi Range to estimate the recurrence cycle.

Keywords: paleoseismology, surface rupture, recurrence interval, Eastern Himalaya

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Authors: Asmamaw Yehun, Tsegaye Gogie, Martin Vermeer, Addisu Hunegnaw

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The Global Positioning System (GPS) is a space-based radio positioning system, which is capable of providing continuous position, velocity, and time information to users anywhere on or near the surface of the Earth. The main objective of this work was to estimate the integrated precipitable water vapour (IPWV) using ground GPS and Low Earth Orbit (LEO) Radio Occultation (RO) to study spatial-temporal variability. For LEO-GPS RO, we used Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) datasets. We estimated the daily and monthly mean of IPWV using six selected ground-based GPS stations over a period of range from 2012 to 2016 (i.e. five-years period). The main perspective for selecting the range period from 2012 to 2016 is that, continuous data were available during these periods at all Ethiopian GPS stations. We studied temporal, seasonal, diurnal, and vertical variations of precipitable water vapour using GPS observables extracted from the precise geodetic GAMIT-GLOBK software package. Finally, we determined the cross-correlation of our GPS-derived IPWV values with those of the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-40 Interim reanalysis and of the second generation National Oceanic and Atmospheric Administration (NOAA) model ensemble Forecast System Reforecast (GEFS/R) for validation and static comparison. There are higher values of the IPWV range from 30 to 37.5 millimetres (mm) in Gambela and Southern Regions of Ethiopia. Some parts of Tigray, Amhara, and Oromia regions had low IPWV ranges from 8.62 to 15.27 mm. The correlation coefficient between GPS-derived IPWV with ECMWF and GEFS/R exceeds 90%. We conclude that there are highly temporal, seasonal, diurnal, and vertical variations of precipitable water vapour in the study area.

Keywords: GNSS, radio occultation, atmosphere, precipitable water vapour

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Authors: Niaz Gharavi, Hexin Zhang

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The shear modulus of a timber beam can be determined using torsion test or shear field test method. The shear field test method is based on shear distortion measurement of the beam at the zone with the constant transverse load in the standardized four-point bending test. The current code of practice advises using two metallic arms act as an instrument to measure the diagonal displacement of the constructing square. The size and the position of the constructing square might influence the shear modulus determination. This study aimed to investigate the size and the position effect of the square in the shear field test method. A binocular stereo vision system has been employed to determine the 3D displacement of a grid of target points. Six glue laminated beams were produced and tested. Analysis of Variance (ANOVA) was performed on the acquired data to evaluate the significance of the size effect and the position effect of the square. The results have shown that the size of the square has a noticeable influence on the value of shear modulus, while, the position of the square within the area with the constant shear force does not affect the measured mean shear modulus.

Keywords: shear field test method, structural-sized test, shear modulus of Glulam beam, photogrammetry approach

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Authors: Ming-Hsiang Shih, Wen-Pei Sung, Shih-Heng Tung

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Semi-active control system for structure under excitation of earthquake provides with the characteristics of being adaptable and requiring low energy. DSHD (Displacement Semi-Active Hydraulic Damper) was developed by our research team. Shake table test results of this DSHD installed in full scale test structure demonstrated that this device brought its energy-dissipating performance into full play for test structure under excitation of earthquake. The objective of this research is to develop a new AIC (Active Interaction Control Device) and apply shake table test to perform its dissipation of energy capability. This new proposed AIC is converting an improved DSHD (Displacement Semi-Active Hydraulic Damper) to AIC with the addition of an accumulator. The main concept of this energy-dissipating AIC is to apply the interaction function of affiliated structure (sub-structure) and protected structure (main structure) to transfer the input seismic force into sub-structure to reduce the structural deformation of main structure. This concept is tested using full-scale multi-degree of freedoms test structure, installed with this proposed AIC subjected to external forces of various magnitudes, for examining the shock absorption influence of predictive control, stiffness of sub-structure, synchronous control, non-synchronous control and insufficient control position. The test results confirm: (1) this developed device is capable of diminishing the structural displacement and acceleration response effectively; (2) the shock absorption of low precision of semi-active control method did twice as much seismic proof efficacy as that of passive control method; (3) active control method may not exert a negative influence of amplifying acceleration response of structure; (4) this AIC comes into being time-delay problem. It is the same problem of ordinary active control method. The proposed predictive control method can overcome this defect; (5) condition switch is an important characteristics of control type. The test results show that synchronism control is very easy to control and avoid stirring high frequency response. This laboratory results confirm that the device developed in this research is capable of applying the mutual interaction between the subordinate structure and the main structure to be protected is capable of transforming the quake energy applied to the main structure to the subordinate structure so that the objective of minimizing the deformation of main structural can be achieved.

Keywords: DSHD (Displacement Semi-Active Hydraulic Damper), AIC (Active Interaction Control Device), shake table test, full scale structure test, sub-structure, main-structure

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Authors: Jimena Lizeth Gomez Delgado, Jhon Jairo Rodriguez, Nicolas Santos, Enrique Mejia Ospino

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Nanotechnology has played an important role in the hydrocarbon industry, recently , due to the unique properties of graphene oxide nanoparticles, they have been incorporated in different studies enhanced oil recovery. Nonetheless, very few studies have used graphene oxide nanoparticles in coreflooding experiments. Herein, the use of Graphene oxide (GO) nanoparticle was explored, exploited and evaluated. The performance of Graphene oxide nanoparticles on the interfacial properties in the presence of different electrolyte concentrations representative of field brine and pH conditions was investigated. Moreover, wettability behavior of the nanofluid at the oil/sand interface was studied used contact angle and Amott Harvey evaluation. Experimental result shows that the adsorption of GO on the sandstone surface changes the wettability of the sandstone from being strongly crude oil-wet to intermediate crude oil-wettability. At 900 ppm formation brine with 8 pH solution and 0.09 wt% nanoparticles concentration, Graphene oxide nanofluid exhibited better performance under the different electrolyte concentration studied. Finally, heavy oil displacement test in sandstone cores showed that oil recovery of Graphene oxide nanofluid had 7% incremental oil recovery over conventional waterflooding.

Keywords: nanoparticle, graphene oxide, nanotechnology, wettability, enhanced oil recovery, coreflooding

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Authors: Woo-seok Choi, Eun-sup Kim, Nam-Seo Park

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The demand for new technique in soft ground improvement continuously increases as general soft ground methods like PBD and DCM have a application problem in soft grounds with deep depth and wide distribution in Southern coast of Korea and Southeast. In this study, partial cement mixing method utilizing geogrid and fixing unit(CMG) is suggested and Finite element analysis is performed for analyzing the depth of surface soil and deep soil stabilization and comparing with DCM method. In the result of the experiment, the displacement in DCM method were lower than the displacement in CMG, it's because the upper load is transferred to deep part soil not treated by cement in CMG method case. The differential settlement in DCM method was higher than the differential settlement in CMG, because of the effect load transfer effect by surface part soil treated by cement and geogrid. In conclusion, CMG method has the advantage of economics and constructability in embankment road, railway, etc in which differential settlement is the important consideration.

Keywords: soft ground, geogrid, fixing unit, partial cement mixing, finite element analysis

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Authors: Thang Minh Le, Hadi Khabbaz

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The coefficient of consolidation is a parameter governing the rate at which saturated soil particularly clay undergoes consolidation when subjected to an increase in pressure. The rate and amount of compression in soil varies with the rate that pore water is lost; and hence depends on soil permeability. Over many years, various methods have been proposed to determine the coefficient of consolidation, cv, which is an indication of the rate of foundation settlement on soft ground. However, defining this parameter is often problematic and heavily relies on graphical techniques, which are subject to some uncertainties. This paper initially presents an overview of many well-established methods to determine the vertical coefficient of consolidation from the incremental loading consolidation tests. An array of consolidation tests was conducted on the undisturbed clay samples, collected at various depths from a site in Nakdong river delta, Busan, South Korea. The consolidation test results on these soft sensitive clay samples were employed to evaluate the targeted methods to predict the settlement rate of Busan clay. In relationship of time-displacement-velocity, a total of 3 method groups from 10 common procedures were classified and compared together. Discussions on study results will be also provided.

Keywords: Busan clay, coefficient of consolidation, constant rate of strain, incremental loading

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Authors: Niloufar Khoshbakht, Peggi L. Clouston, Sanjay R. Arwade, Alexander C. Schreyer

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Laminated veneer bamboo (LVB) is a structural engineered composite made from glued layers of bamboo. A relatively new building product, LVB is currently employed in similar sizes and applications as dimensional lumber. This study describes the results of a 3D elastic Finite Element model for halfhole specimens when loaded in compression parallel-to-grain per ASTM 5764. The model simulates LVB fracture initiation due to shear stresses in the dowel joint and predicts displacement at failure validated through comparison with experimental results. The material fails at 1mm displacement due to in-plane shear stresses. The paper clarifies the complex interactive state of in-plane shear, tension perpendicular-to-grain, and compression parallel-to-grain stresses that form different distributions in the critical zone beneath the bolt hole for half-hole specimens. These findings are instrumental in understanding key factors and fundamental failure mechanisms that occur in LVB dowel connections to help devise safe standards and further LVB product adoption and design.

Keywords: composite, dowel connection, embedment strength, failure behavior, finite element analysis, Moso bamboo

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Authors: Tao Chen, ShiHua Liu, JiWei Zhang

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Assembly of the proton exchange membrane fuel cells (PEMFC) has a very important influence on its performance and efficiency. The various components of PEMFC stack are usually locked and fixed by bolts. Locking bolt will cause the deformation of the bipolar plate and the other components, which will affect directly the deformation degree of the integral parts of the PEMFC as well as the performance of PEMFC. This paper focuses on the object of three-cell stack of PEMFC. Finite element simulation is used to investigate the deformation of bipolar plate caused by quantity and layout of bolts, bolt locking pressure, and bolt locking sequence, etc. Finally, we made a conclusion that the optimal combination packaging scheme was adopted to assemble the fuel cell stack. The scheme was in use of 3.8 MPa locking pressure imposed on the fuel cell stack, type Ⅱ of four locking bolts and longitudinal locking method. The scheme was obtained by comparatively analyzing the overall displacement contour of PEMFC stack, absolute displacement curve of bipolar plate along the given three paths in the Z direction and the polarization curve of fuel cell. The research results are helpful for the fuel cell stack assembly.

Keywords: bipolar plate, deformation, finite element simulation, fuel cell, locking bolt

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Authors: Cheryl-Ann Sarita Boodram

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Historically, the movement of people has been the subject of socio-political and economic regulatory policies which congeal to regulate human mobility and establish geopolitical and spatial identities and borderlands. As migratory practices evolved, so too has the problematization associated with movement, migration and citizenship. The emerging trends have led to active development of immigration technology governing human mobility and the naming of migratory practices. One such named phenomenon is ‘deportation’ or the forced removal of individuals from their adopted country. Deportation, has gained much attention within the human mobility landscape in the past twenty years following the September 2001 terrorist attack on the World Trade Centre in New York. In a reactionary move, several metropolitan countries, including Canada and the United Kingdom enacted or reviewed immigration laws which further enabled the removal of foreign born criminals to the land of their birth in the global south. Existing studies fall short of understanding the multiple textures of the forced returned migration experiences and the social injustices resulting from deportation displacement. This study brings together indigenous research methodologies through the use of participatory action research and social work with returned migrants in Trinidad and Tobago to uncover the experiences of displacement of deported nationals. The study explores the experiences of negotiating life as a ‘stranger’ and how return has influenced the construction of identities of returned nationals. Findings from this study reveal that deportation has led to inequalities and facilitated ‘othering’ of this group within their own country of birth. The study further highlighted that deportation leads to circuits of dispossession, and perpetuates inequalities. This study provides original insights into the way returned migrants negotiate, map and embody ‘strangeness’ and manage their return to a soil they consider unfamiliar and alien.

Keywords: stranger, alien geographies, displacement, deportation, negotiating strangeness, identity, otherness, alien landscapes

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Authors: Yuanda Ma, Zhiyong Zhang, Zailin Yang, Guanxixi Jiang

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Anisotropy is very common in underground media, such as rock, sand, and soil. Hence, the dynamic response of anisotropy medium under elastic waves is significantly different from the isotropic one. Moreover, underground heterogeneities and structures, such as pipelines, cylinders, or tunnels, are usually made by composite materials, leading to the anisotropy of these heterogeneities and structures. Both the anisotropy of the underground medium and the heterogeneities have an effect on the surface motion of the ground. Aiming at providing theoretical references for earthquake engineering and seismology, the surface motion of anisotropic half-space with a cylindrical anisotropic inclusion embedded under the SH wave is investigated in this work. Considering the anisotropy of the underground medium, the governing equation with three elastic parameters of SH wave propagation is introduced. Then, based on the complex function method and multipolar coordinates system, the governing equation in the complex plane is obtained. With the help of a pair of transformation, the governing equation is transformed into a standard form. By means of the same methods, the governing equation of SH wave propagation in the cylindrical inclusion with another three elastic parameters is normalized as well. Subsequently, the scattering wave in the half-space and the standing wave in the inclusion is deduced. Different incident wave angle and anisotropy are considered to obtain the reflected wave. Then the unknown coefficients in scattering wave and standing wave are solved by utilizing the continuous condition at the boundary of the inclusion. Through truncating finite terms of the scattering wave and standing wave, the equation of boundary conditions can be calculated by programs. After verifying the convergence and the precision of the calculation, the validity of the calculation is verified by degrading the model of the problem as well. Some parameters which influence the surface displacement of the half-space is considered: dimensionless wave number, dimensionless depth of the inclusion, anisotropic parameters, wave number ratio, shear modulus ratio. Finally, surface displacement amplitude of the half space with different parameters is calculated and discussed.

Keywords: anisotropy, complex function method, sh wave, surface displacement amplitude

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Authors: E. Irankhah, M. Zarif, E. Mazrooei Rad, K. Ghandehari

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Alzheimer's prevalence is on the rise, and the disease comes with problems like cessation of treatment, high cost of treatment, and the lack of early detection methods. The pathology of this disease causes the formation of protein deposits in the brain of patients called plaque amyloid. Generally, the diagnosis of this disease is done by performing tests such as a cerebrospinal fluid, CT scan, MRI, and spinal cord fluid testing, or mental testing tests and eye tracing tests. In this paper, we tried to use the Medial Temporal Atrophy (MTA) method and the Leave One Out (LOO) cycle to extract the statistical properties of the three Fz, Pz, and Cz channels of ERP signals for early diagnosis of this disease. In the process of CT scan images, the accuracy of the results is 81% for the healthy person and 88% for the severe patient. After the process of ERP signaling, the accuracy of the results for a healthy person in the delta band in the Cz channel is 81% and in the alpha band the Pz channel is 90%. In the results obtained from the signal processing, the results of the severe patient in the delta band of the Cz channel were 89% and in the alpha band Pz channel 92%.

Keywords: Alzheimer's disease, image and signal processing, LOO cycle, medial temporal atrophy

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Authors: Jason Clarke, Michaela Porubanova, Angela Mazzoli, Gulsah Kut

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What accounts for our perception that time inexorably passes in one direction, from the past to the future, the so-called arrow of time, given that the laws of physics permit motion in one temporal direction to also happen in the reverse temporal direction? Modern physics says that the reason for time’s unidirectional physical arrow is the relationship between time and entropy, the degree of disorder in the universe, which is evolving from low entropy (high order; thermal disequilibrium) toward high entropy (high disorder; thermal equilibrium), the second law of thermodynamics. Accordingly, our perception of the direction of time, from past to future, is believed to emanate as a result of the natural evolution of entropy from low to high, with low entropy defining our notion of ‘before’ and high entropy defining our notion of ‘after’. Here we explored this proposed relationship between entropy and the perception of time’s arrow. We predicted that if the brain has some mechanism for detecting entropy, whose output feeds into processes involved in constructing our perception of the direction of time, presentation of violations to the expectation that low entropy defines ‘before’ and high entropy defines ‘after’ would alert this mechanism, leading to measurable behavioral effects, namely a disruption in duration perception. To test this hypothesis, participants were shown briefly-presented (1000 ms or 500 ms) computer-generated visual dynamic events: novel 3D shapes that were seen either to evolve from whole figures into parts (low to high entropy condition) or were seen in the reverse direction: parts that coalesced into whole figures (high to low entropy condition). On each trial, participants were instructed to reproduce the duration of their visual experience of the stimulus by pressing and releasing the space bar. To ensure that attention was being deployed to the stimuli, a secondary task was to report the direction of the visual event (forward or reverse motion). Participants completed 60 trials. As predicted, we found that duration reproduction was significantly longer for the high to low entropy condition compared to the low to high entropy condition (p=.03). This preliminary data suggests the presence of a neural mechanism that detects entropy, which is used by other processes to construct our perception of the direction of time or time’s arrow.

Keywords: time perception, entropy, temporal illusions, duration perception

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Authors: Karen Cilliers, Benedict John Page

Abstract:

The middle cerebral artery (MCA) is the most complex cerebral artery although few anomalies are found compared to the other cerebral arteries. The branches of the MCA cover a large part of each hemisphere, therefore it is exposed in various operations. Although the segments of the MCA are similarly described by most authors, there is some disagreement on the branching pattern of the MCA. The aim of this study was to review the available literature on the anatomy and variations of the MCA, and to compare this to a pilot study. For the pilot study, 20 hemispheres were perfused with coloured silicone and the MCA was dissected. According to the literature, the two most common branching configurations are the bifurcating and trifurcating patterns. In the pilot study, bifurcation was observed in 19 hemispheres, and in one hemisphere there was no branching (monofurcation). No trifurcation was observed. The most commonly duplicated branch was the anterior parietal artery in 30%, and most commonly absent was the common temporal artery in 65% and the temporal polar artery in 40%. Very few studies describe the origins of the branches of the MCA, therefore a detailed description is given. Middle cerebral artery variations that are occasionally reported in the literature include fenestration, and a duplicated or accessory MCA, although no variations were observed in the pilot study. Aneurysms can frequently be observed at the branching of cerebral vessels, therefore a thorough knowledge of the vascular anatomy is vital. Furthermore, knowledge of possible variations is important since variations can have serious clinical implications.

Keywords: anatomy, anomaly, description, middle cerebral artery, origin, variation

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Authors: Ehsan Sadie

Abstract:

The use of steel braces in concrete structures has been considered by researchers in recent decades due to its easy implementation, economics and the ability to create skylights in braced openings compared to shear wall openings as well as strengthening weak concrete structures to earthquakes. The purpose of this article is to improve and strengthen concrete structures with steel bracing. In addition, cases such as different numbers of steel braces in different openings of concrete structures and interaction between concrete frames and metal braces have been studied. In this paper, by performing static nonlinear analysis and examining ductility, the relative displacement of floors, examining the performance of samples, and determining the coefficient of behavior of composite frames (concrete frames with metal bracing), the behavior of reinforced concrete frames is compared with frame without bracing. The results of analyzes and studies show that the addition of metal bracing increases the strength and stiffness of the frame and reduces the ductility and lateral displacement of the structure. In general, the behavior of the structure against earthquakes will be improved.

Keywords: behavior coefficient, bracing, concrete structure, convergent bracing, earthquake, linear static analysis, nonlinear analysis, pushover curve

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Authors: Sneha Kumari, Ravi Krishnan Elangovan

Abstract:

This abstract describes the development of a high-speed tracking method by modification in motor components for nanoparticle attachment. Myosin motors are nano-sized protein machines powering movement that defines life. These miniature molecular devices serve as engines utilizing chemical energy stored in ATP to produce useful mechanical energy in the form of a few nanometre displacement events leading to force generation that is required for cargo transport, cell division, cell locomotion, translated to macroscopic movements like running etc. With the advent of in vitro motility assay (IVMA), detailed functional studies of the actomyosin system could be performed. The major challenge with the currently available IVMA for tracking actin filaments is a resolution limitation of ± 50nm. To overcome this, we are trying to develop Single Molecule IVMA in which nanoparticle (GNP/QD) will be attached along or on the barbed end of actin filaments using CapZ protein and visualization by a compact TIRF module called ‘cTIRF’. The waveguide-based illumination by cTIRF offers a unique separation of excitation and collection optics, enabling imaging by scattering without emission filters. So, this technology is well equipped to perform tracking with high precision in temporal resolution of 2ms with significantly improved SNR by 100-fold as compared to conventional TIRF. Also, the nanoparticles (QD/GNP) attached to actin filament act as a point source of light coffering ease in filament tracking compared to conventional manual tracking. Moreover, the attachment of cargo (QD/GNP) to the thin filament paves the way for various nano-technological applications through their transportation to different predetermined locations on the chip

Keywords: actin, cargo, IVMA, myosin motors and single-molecule system

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Authors: Shreya Borthakur, Aastha Vartak

Abstract:

This Electroencephalogram (EEG) project on Rapid Visual Serial Processing (RSVP) paradigm explores the temporal dynamics of visual attention processing in response to rapidly presented visual stimuli. The study builds upon previous research that used real-world images in RSVP tasks to understand the emergence of object representations in the human brain. The objectives of the research include investigating the differences in accuracy and reaction times between 5 Hz and 20 Hz presentation rates, as well as examining the prominent brain waves, particularly alpha and beta waves, associated with the attention task. The pre-processing and data analysis involves filtering EEG data, creating epochs for target stimuli, and conducting statistical tests using MATLAB, EEGLAB, Chronux toolboxes, and R. The results support the hypotheses, revealing higher accuracy at a slower presentation rate, faster reaction times for less complex targets, and the involvement of alpha and beta waves in attention and cognitive processing. This research sheds light on how short-term memory and cognitive control affect visual processing and could have practical implications in fields like education.

Keywords: RSVP, attention, visual processing, attentional blink, EEG

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Authors: Minho Kwon, Seonghyeok Lee, Wooyoung Jung

Abstract:

In recent years, with increase of construction of skyscraper structures, the study of concrete materials to improve their weight and performance has been emerging as a key of research area. Typically, the concrete structures has disadvantage of increasing the weight due to its mass in comparison to the strength of the materials. Therefore, in order to improve such problems, the light-weight aggregate concrete and high strength concrete materials have been studied during the past decades. On the other hand, the study of light-weight aggregate concrete materials has lack of data in comparison to the concrete structure using high strength materials, relatively. Consequently, this study presents the performance characteristics of light-weight aggregate concrete materials due to the material properties and strength. Also, this study conducted the experimental tests with respect to normal and lightweight aggregate materials, in order to indentify the tensile crack failure of the concrete structures. As a result, the Crack Mouth Opening Displacement (CMOD) from the experimental tests was constructed and the fracture energy using inverse problem analysis was developed from the force-CMOD relationship in this study, respectively.

Keywords: lightweight aggregate concrete, crack mouth opening displacement, inverse analysis, fracture energy

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Authors: Maria Ezziani, Rabie Zine, Amine Amar, Ilhame Kissani

Abstract:

This paper introduces a predictive model for urban transportation engineering, which is vital for efficient traffic management. Utilizing comprehensive datasets and advanced statistical techniques, the model accurately forecasts travel times by considering temporal variations and traffic dynamics. Machine learning algorithms, including regression trees and neural networks, are employed to capture sequential dependencies. Results indicate significant improvements in predictive accuracy, particularly during peak hours and holidays, with the incorporation of traffic flow and speed variables. Future enhancements may integrate weather conditions and traffic incidents. The model's applications range from adaptive traffic management systems to route optimization algorithms, facilitating congestion reduction and enhancing journey reliability. Overall, this research extends beyond travel time estimation, offering insights into broader transportation planning and policy-making realms, empowering stakeholders to optimize infrastructure utilization and improve network efficiency.

Keywords: predictive analytics, traffic flow, travel time estimation, urban transportation, machine learning, traffic management

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Authors: M. Kozłowski, M. Kadela

Abstract:

Foamed concrete is known for its low self-weight and excellent thermal and acoustic properties. For many years, it has been used worldwide for insulation to foundations and roof tiles, as backfill to retaining walls, sound insulation, etc. However, in the last years it has become a promising material also for structural purposes e.g. for stabilization of weak soils. Due to favorable properties of foamed concrete, many interests and studies were involved to analyze its strength, mechanical, thermal and acoustic properties. However, these studies do not cover the investigation of fracture energy which is the core factor governing the damage and fracture mechanisms. Only limited number of publications can be found in literature. The paper presents the results of experimental investigation and numerical campaign of foamed concrete based on three-point bending test of beams with initial notch. First part of the paper presents the results of a series of static loading tests performed to investigate the fracture properties of foamed concrete of varying density. Beam specimens with dimensions of 100×100×840 mm with a central notch were tested in three-point bending. Subsequently, remaining halves of the specimens with dimensions of 100×100×420 mm were tested again as un-notched beams in the same set-up with reduced distance between supports. The tests were performed in a hydraulic displacement controlled testing machine with a load capacity of 5 kN. Apart from measuring the loading and mid-span displacement, a crack mouth opening displacement (CMOD) was monitored. Based on the load – displacement curves of notched beams the values of fracture energy and tensile stress at failure were calculated. The flexural tensile strength was obtained on un-notched beams with dimensions of 100×100×420 mm. Moreover, cube specimens 150×150×150 mm were tested in compression to determine the compressive strength. Second part of the paper deals with numerical investigation of the fracture behavior of beams with initial notch presented in the first part of the paper. Extended Finite Element Method (XFEM) was used to simulate and analyze the damage and fracture process. The influence of meshing and variation of mechanical properties on results was investigated. Numerical models simulate correctly the behavior of beams observed during three-point bending. The numerical results show that XFEM can be used to simulate different fracture toughness of foamed concrete and fracture types. Using the XFEM and computer simulation technology allow for reliable approximation of load–bearing capacity and damage mechanisms of beams made of foamed concrete, which provides some foundations for realistic structural applications.

Keywords: foamed concrete, fracture energy, three-point bending, XFEM

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