Search results for: circular film cooling channel

Authors: M. Wasy Akhtar

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Multi-modal film boiling simulations are carried out on adaptive octree grids. The liquid-vapor interface is captured using the volume-of-fluid framework adjusted to account for exchanges of mass, momentum, and energy across the interface. Surface tension effects are included using a volumetric source term in the momentum equations. The phase change calculations are conducted based on the exact location and orientation of the interface; however, the source terms are calculated using the mixture variables to be consistent with the one field formulation used to represent the entire fluid domain. The numerical model on octree representation of the computational grid is first verified using test cases including advection tests in severely deforming velocity fields, gravity-based instabilities and bubble growth in uniformly superheated liquid under zero gravity. The model is then used to simulate both single and multi-modal film boiling simulations. The octree grid is dynamically adapted in order to maintain the highest grid resolution on the instability fronts using markers of interface location, volume fraction, and thermal gradients. The method thus provides an efficient platform to simulate fluid instabilities with or without phase change in the presence of body forces like gravity or shear layer instabilities.

Keywords: boiling flows, dynamic octree grids, heat transfer, interface capturing, phase change

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Authors: A. C. Galvis-Castro, R. D. Tovar, R. Salgado, M. Prezzi

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It is generally accepted that the shaft capacity of piles in the sand is lower for tensile loading that for compressive loading. So far, very little attention has been paid to the role of the influence of the installation method on the tensile to compressive shaft capacity ratio. The objective of this paper is to analyze the effect of installation method on the tensile to compressive shaft capacity of piles in dense sand as observed in tests on half-circular model pile tests in a half-circular calibration chamber with digital image correlation (DIC) capability. Model piles are either monotonically jacked, jacked with multiple strokes or pre-installed into the dense sand samples. Digital images of the model pile and sand are taken during both the installation and loading stages of each test and processed using the DIC technique to obtain the soil displacement and strain fields. The study provides key insights into the mobilization of shaft resistance in tensile and compressive loading for both displacement and non-displacement piles.

Keywords: digital image correlation, piles, sand, shaft resistance

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Authors: Juliana Barcelos Cordeiro, Khashayar Mahani, Farbod Farzan, Mohsen A. Jafari

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Energy disaggregation has been focused by many energy companies since energy efficiency can be achieved when the breakdown of energy consumption is known. Companies have been investing in technologies to come up with software and/or hardware solutions that can provide this type of information to the consumer. On the other hand, not all people can afford to have these technologies. Therefore, in this paper, we present a methodology for breaking down the aggregate consumption and identifying the highdemanding end-uses profiles. These energy profiles will be used to build the forecast model for optimal control purpose. A facility with high cooling load is used as an illustrative case study to demonstrate the results of proposed methodology. We apply a high level energy disaggregation through a pattern recognition approach in order to extract the consumption profile of its rooftop packaged units (RTUs) and present a forecast model for the energy consumption.  

Keywords: energy consumption forecasting, energy efficiency, load disaggregation, pattern recognition approach

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Authors: B. Umaru Mohammed, Faris A. Al-Maziad, Mohammad Y. Numan

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One of the most important factors affecting the energy performance within a building is a carefully and efficiently designed facade. The primary aim of this research was to identify and present the potentiality of utilising Double-Skin Facade (DSF) construction and critically examine its effect on the energy consumption of an office building located within a maritime desert climate as to the conventional single-skin curtain wall system. A comparative analysis of the effect on the overall energy consumption within an office building was investigated in which a combination of various Double-Skin Facade configurations, systems, and cavity depths, glazing types and orientations were utilised. A computer dynamic modelling was utilised in order to ensure accurate calculations and efficient simulations of the various DSF systems due to the complex nature of the various functions within the Facade cavity. Through the use of the dynamic thermal modelling simulations, the best cavity size glazed type and orientation were determined to lead to a detailed analysis of the efficiency of each respective combination of Double-Skin Facade construction. As such the optimal facade combination for use within an office building located in a maritime desert climate was identified. Results demonstrated that a multi-story Facade, depending on its configuration, save up to 5% on annual cooling loads respect to a Corridor Facade and while vented can save unto 12% when compared to the single skin façade, on annual cooling load in the maritime desert climate. The selected configuration of the DSF from SSF saves an overall annual cooling load of 32%.A comparative analysis of the effect on the overall energy consumption within an office building was investigated in which a combination of various Double-Skin Facade configurations, systems, and cavity depths, glazing types and orientations were utilized. A computer dynamic modelling was utilized in order to ensure accurate calculations and efficient simulations of the various DSF systems due to the complex nature of the various functions within the Facade cavity. Through the use of the dynamic thermal modelling simulations, the best cavity size glazed type and orientation were determined to lead to a detailed analysis of the efficiency of each respective combination of Double-Skin Facade construction. As such the optimal facade combination for use within an office building located in a maritime desert climate was identified. Results demonstrated that a multi-story Facade, depending on its configuration, save up to 5% on annual cooling loads respect to a Corridor Facade and while vented can save unto 12% when compared to the single skin facade, on annual cooling load in the maritime desert climate. The selected configuration of the DSF from SSF saves an overall annual cooling load of 32%.

Keywords: computer dynamics modelling, comparative analysis, energy computation, double skin facade, single skin curtain wall, maritime desert climate

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Authors: Jie Xu, Zengshan Tian, Ze Li

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Previous indoor ranging or localization systems achieving high accuracy time of flight (ToF) estimation relied on two key points. One is to do strict time and frequency synchronization between the transmitter and receiver to eliminate equipment asynchronous errors such as carrier frequency offset (CFO), but this is difficult to achieve in a practical communication system. The other one is to extend the total bandwidth of the communication because the accuracy of ToF estimation is proportional to the bandwidth, and the larger the total bandwidth, the higher the accuracy of ToF estimation obtained. For example, ultra-wideband (UWB) technology is implemented based on this theory, but high precision ToF estimation is difficult to achieve in common WiFi or Bluetooth systems with lower bandwidth compared to UWB. Therefore, it is meaningful to study how to achieve high-precision ranging with lower bandwidth when the transmitter and receiver are asynchronous. To tackle the above problems, we propose a two-way channel error elimination theory and a frequency hopping-based carrier phase ranging algorithm to achieve high accuracy ranging under asynchronous conditions. The two-way channel error elimination theory uses the symmetry property of the two-way channel to solve the asynchronous phase error caused by the asynchronous transmitter and receiver, and we also study the effect of the two-way channel generation time difference on the phase according to the characteristics of different hardware devices. The frequency hopping-based carrier phase ranging algorithm uses frequency hopping to extend the equivalent bandwidth and incorporates a carrier phase ranging algorithm with multipath resolution to achieve a ranging accuracy comparable to that of UWB at 400 MHz bandwidth in the typical 80 MHz bandwidth of commercial WiFi. Finally, to verify the validity of the algorithm, we implement this theory using a software radio platform, and the actual experimental results show that the method proposed in this paper has a median ranging error of 5.4 cm in the 5 m range, 7 cm in the 10 m range, and 10.8 cm in the 20 m range for a total bandwidth of 80 MHz.

Keywords: frequency hopping, phase error elimination, carrier phase, ranging

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Authors: Kadri-Ann Kertsmik, Martin Talvik, Kimmo Lylykangas, Simo Ilomets, Targo Kalamees

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This study compares the building carbon footprint (CF) values for a case study of a private house located in a cold climate, using the Level(s) methodology. It provides a framework for measuring the environmental performance of buildings throughout their life cycle, taking into account various factors. The study presents the results of the three scenarios, comparing their carbon emissions and highlighting the benefits of circular material usage. The construction process was thoroughly documented, and all materials and components (including minuscule mechanical fasteners, each meter of cable, a kilogram of mortar, and the component of HVAC systems, among other things) delivered to the construction site were noted. Transportation distances of each delivery, the fuel consumption of construction machines, and electricity consumption for temporary heating and electrical tools were also monitored. Using the detailed data on material and energy resources, the CF was calculated for two scenarios: one where circular material usage was applied and another where virgin materials were used instead of reused ones. The results were compared with the CF calculated based on the building permit design model using the Level(s) methodology. To study the range of possible results in the early stage of CF assessment, the same building permit design was given to several experts. Results showed that embodied carbon values for a built scenario were significantly lower than the values predicted by the building permit stage as a result of more precise material quantities, as the calculation methodology is designed to overestimate the CF. Moreover, designers made an effort to reduce the building's CF by reusing certain materials such as ceramic tiles, lightweight concrete blocks, and timber during the construction process. However, in a cold climate context where operational energy (B6) continues to dominate, the total building CF value changes between the three scenarios were less significant. The calculation for the building permit project was performed by several experts, and CF results were in the same range. It alludes that, for the first estimation of preliminary building CF, using average values proves to be an appropriate method for the Estonian national carbon footprint estimation phase during building permit application. The study also identified several opportunities for reducing the carbon footprint of the building, such as reusing materials from other construction sites, preferring local material producers, and reducing wastage on site. The findings suggest that using circular materials can significantly reduce the carbon footprint of buildings. Overall, the study highlights the importance of using a comprehensive approach to measure the environmental performance of buildings, taking into account both the project and the actually built house. It also emphasises the need for ongoing monitoring for designing the building and construction site waste. The study also gives some examples of how to enable future circularity of building components and materials, e.g., building in layers, using wood as untreated, etc.

Keywords: carbon footprint, circular economy, sustainable construction, level(s) methodology

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Authors: Aniekan James Akpan

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The use of signs and symbols to represent cardinal information is inalienable among African communities. It has been the tenable instrument of cultural transmission for decades, but in the current transposal of Western values, a good number of communicating codes and symbolic images have been gradually relegated to the background. This paper discusses the regeneration of cultural artifacts and sign languages in Nigerian films using Johnpaul Rebecca and Ayamma as models in a qualitative research based on Charles Sanders Pierce's Semiotics as well as quantitative methods of survey using questionnaire and focus group discussion as instruments to obtain data. With a population of 2,343 viewers of the movies used for the study and a sample size of 322 respondents using Philip Meyer’s guide, findings show that cultural relics can stabilise the subject matter of a film. Artifacts can stimulate curiosity and invoke nostalgia. Sign languages encode deeper information that ordinary speech may not properly convey in films. It concludes that the use of non-verbal codes in filmmaking deserves deep research into the culture portrayed and that non-verbal cues communicate deeper information about a people's cosmos in a film than dialogue. It recommends that adequate research should be made before producing a film and the idea of cultural values represented in artifacts and sign language should be ingrained in the courses for students to acquaint themselves with.

Keywords: cultural artifact, Nollywood films, non-verbal communication, sign language

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Authors: Salman Piri

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In this study, a two-dimensional lattice Boltzmann method (LBM) was considered for the numerical simulation of fluid flow in a channel. Also, the Lagrangian method was used for particle tracking in one-way coupling. Three hundred spherical particles with specific diameters were released in the channel entry and an elliptical object was placed in the channel for flow obstruction. The effect of gravity, the drag force, the Saffman lift and the Brownian forces were evaluated in the particle motion trajectories. Also, the effect of the geometrical parameter, ellipse aspect ratio, and the flow characteristic or Reynolds number was surveyed for the transport and deposition of particles. Moreover, the influence of particle diameter between 0.01 and 10 µm was investigated. Results indicated that in small Reynolds, more inertial and gravitational trapping occurred on the obstacle surface for particles with larger diameters. Whereas, for nano-particles, influenced by Brownian diffusion and vortices behind the obstacle, the inertial and gravitational mechanisms were insignificant and diffusion was the dominant deposition mechanism. In addition, in Reynolds numbers larger than 400, there was no significant difference between the deposition of finer and larger particles. Also, in higher aspect ratios of the ellipse, more inertial trapping occurred for particles of larger diameter (10 micrometers), while in lower cases, interception and gravitational mechanisms were dominant.

Keywords: ellipse aspect elito, particle tracking diffusion, lattice boltzman method, larangain particle tracking

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Authors: Chebli Derradji, Abdallah Bouguettoucha, Zoubir Manaa, S. Nacef, A. Amrane

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Antibiotics are major pollutants of wastewater not only due to their stability in biological systems, but also due to their impact on public health. Their degradation by means of hydroxyl radicals generated through the application of microwave in the presence of hydrogen peroxide and two solid catalysts, iron-based synthetic clay (LDHs) and goethite (FeOOH) have been examined. A drastic reduction of the degradation yield was observed above pH 4, and hence the optimal conditions were found to be a pH of 3, 0.1 g/L of clay, a somewhat low amount of H2O2 (1.74 mmol/L) and a microwave intensity of 850 W. It should be observed that to maintain an almost constant temperature, a cooling with cold water was always applied between two microwaves running; and hence the ratio between microwave heating time and cooling time was 1. The obtained SMX degradation was 98.8 ± 0.2% after 30 minutes of microwave treatment. It should be observed that in the absence of the solid catalyst, LDHs, no SMX degradation was observed. From this, the use of microwave in the presence of a solid source of iron (LDHs) appears to be an efficient solution for the treatment of wastewater containing SMX.

Keywords: microwave, fenton, heterogenous fenton, degradation, oxidation, antibiotics

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Authors: Y. Lasbet, A. L. Boukhalkhal, K. Loubar

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The study of mixed convection is, usually, focused on the straight channels in which the onset of the mixed convection is well defined as function of the ratio between Grashof number and Reynolds number, Gr/Re. This is not the case for a complex channel wherein the mixed convection is not sufficiently examined in the literature. Our paper focuses on the study of the mixed convection in a complex geometry in which our main contribution reveals that the critical value of the ratio Gr/Re for the onset of the mixed convection increases highly in the type of geometry contrary to the straight channel. Furthermore, the accentuated secondary flow in this geometry prevents the thermal stratification in the flow and consequently the buoyancy driven becomes negligible. To perform these objectives, a numerical study in complex geometry for several values of the ratio Gr/Re with prescribed wall heat flux (H2), was realized by using the CFD code.

Keywords: complex geometry, heat transfer, laminar flow, mixed convection, Nusselt number

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Authors: Ashish Mahalle, Kishore Borakhade

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High porosity metal foams are excellent for heat dissipation. There use has been widened to include heat removal from high density microelectronics circuits. Other important applications have been found in compact heat exchangers for airborne equipment, regenerative and dissipative air cooled condenser towers, and compact heat sinks for power electronic. The low relative density, open porosity and high thermal conductivity of the cell edges, large accessible surface area per unit volume, and the ability to mix the cooling fluid make metal foam heat exchangers efficient, compact and light weight. This paper reports the thermal performance of metal foam for high heat dissipation. In experimentation metal foam samples of different pore diameters i.e. 35 µ, 20 µ, 12 µ, are analyzed for varying velocities and heat inputs. The study investigate the effect of various dimensionless no. like Re,Nu, Pr and heat transfer characteristics of basic flow configuration.

Keywords: pores, foam, effective thermal conductivity, permeability

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Authors: Mrunmayee Das

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This study aims to explore the film 'Pyasa' directed by actor-director Guru Dutt, filmed during the 1950’s golden age of Hindi cinema. 'Pyasa' was filmed after a decade of India being a new nation and narrates the world-view of a poet dressed in western ideals, tasting modernity, uprooted from his familial and social moorings causing friction of being between survival and self- expression. The research is based on literature review to study the attitudes, particularly the post-colonial, informing the film. In terms of the structure, the relational study of the film and the historical background of that time came first. Further explorations deal with the use of image making, dialogue, and poetry in the form of songs facilitating the central theme of the human plight of poverty, not of material but of thought. The literature review establishes Dutt’s style of expressing melodic melodrama through a dance between light and shadow majorly in the form of song sequences signifying the greys of the society. It was found in this research that melodrama is created by the changing contrasts and use of close-ups. The song sequences convey the tensions of being a contemporary liberal educated youth and having to deal with the societal-ills of this world, which highlights the theme of compulsion towards self-destruction. It is concluded that Dutt’s 'Pyasa' is a autobiographical commentary on the state of a nation doing away with a borrowed identity and refashioning its own.

Keywords: cinema, Guru Dutt, post-colonial India, self-expression

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Authors: Misha Nedeljkovich

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In the film’s famous scene (Roma città aperta-1945), Pina (Anna Magnani) collapses in the street when machined-gunned by a German soldier. Her son Marcello (Vito Annchiarico) tries to revive her. Her death is signaling not closure, but the cycle of life; Marcello saves Francesco with the shawl taken from his mother’s corpse. One pivotal scene in Brief Encounter (1945) occurs in the apartment of Alec’s (Trevor Howard) friend Stephen (Valentine Dyall), when Stephen returns to catch Alec and Laura (Celia Johnson) together alone. David Lean directs this scene using her shawl as a sign of in flagrante delicto. In La Strada (1954), Gelsomina (Giulietta Masina) was waving good bye when her mother sensing impending doom changed her mind and desperately tried to stop her waving back with her shawl: Don’t go my daughter! Your shawl! Your shawl! Gelsomina refuses to return, waving back: It’s time to go! Stanley Kubrick’s tale of a boxer who crosses a mobster to win the heart of a lady, Killer’s Kiss (1955), reminds us that Times Square used to contain sweaty boxing gyms and dance halls. The film’s longest Times Square interlude is its oddest: the boxer Davie Gordon played by Jamie Smith has his shawl stolen by two playful men in Shriners’ hats who are silent except for one who blows a harmonica, faintly heard over honking cabs and overheard conversations. This long sequence appears to be joining in on directors’ shawl conversations with Kubrick’s own twist. Principle characters will never know why all this happened to them that evening. Love, death, happiness and everlasting misery all of that is caused by Dave’s shawl. Finally, the decade of cinematic shawl conversations conclude in Betolucci’s Before the Revolution (Prima della rivoluzione–1964). One of his character’s lifts up a shawl asking if this was a Rossellini’s shawl. I argue that exploring complimentary allusions in a film where directors are acknowledging their own great debt to another film or filmmaker will further our knowledge of film history adding both depth and resonance to the great works in cinema.

Keywords: allusions, Bertolucci, Fellini, homage, Kubrick, lean, Rossellini

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Authors: Soottawat Benjakul, Phakawat Tongnuanchan, Thummanoon Prodpran

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Edible pouches made from fish gelatin film incorporated without and with palm oil (PO), basil essential oil (BEO) or oil mixture (M) were prepared and used to store chicken powder and chicken skin oil in comparison with nylon/low-density polyethylene (Nylon/LDPE) pouch during storage of 15 days. The moisture content of chicken powder packaged in pouches from fish gelatin films incorporated without and with various oils increased during 15 days of storage (p > 0.05). However, there was a non-significant change in moisture content of sample packaged in Nylon/LDPE pouch (p > 0.05). Samples packaged in pouches from fish gelatin films incorporated with oils had lower moisture content than those stored in pouch from gelatin film without oil added throughout the storage (p < 0.05). This coincided with the higher increases in darkness and yellowness for the latter. All samples packaged in pouches made from all films had the slight increase in PV, whereas a drastic increase in TBARS was observed for all samples during 15 days of storage. During 15 days of storage, chicken skin oil packaged in Nylon/LDPE pouch had higher TBARS and p-anisidine value than those stored in pouches made from fish gelatin, regardless of oil incorporated (p< 0.05). Therefore, pouches from gelatin film incorporated with oils could lower water migration and lipid oxidation in fat containing foods and oils.

Keywords: edible pouch, fish gelatin, quality changes, storage stability

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Authors: Feyza Şahi̇n, Harun Deni̇zli̇, Mustafa Zabun, Hüseyi̇n OnbaşIoğli

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Heat exchangers are devices that are widely used to transfer heat between fluids due to their temperature differences. As a type of heat exchanger, air coolers are heat exchangers that cool the air as it passes through the fins of the heat exchanger by transferring heat to the refrigerant in the coil tubes of the heat exchanger. An assembled fin and tube heat exchanger consists of a coil block and a casing with a fan mounted on it. The term “Fan hood” is used to define the distance between the fan and the coil block. Air coolers play a crucial role in cooling systems, and their heat transfer performance can vary depending on design parameters. These parameters can be related to the air side or the internal fluid side. For airside efficiency, the distance between the fan and the coil block affects the performance by creating dead zones at the corners of the casing and maldistribution of airflow. Therefore, a detailed study of the effect of the fan hood on the evaporator and the optimum fan hood distance is necessary for an efficient air cooler design. This study aims to investigate the value of the fan hood in a fin and tube-type air cooler heat exchanger through computational fluid dynamics (CFD) simulations and experimental investigations. CFD simulations will be used to study the airflow within the fan hood. These simulations will provide valuable insights to optimize the design of the fan hood. In addition, experimental tests will be carried out to validate the CFD results and to measure the performance of the fan hood under real conditions. The results will help us to understand the effect of fan hood design on evaporator efficiency and contribute to the development of more efficient cooling systems. This study will provide essential information for evaporator design and improving the energy efficiency of cooling systems.

Keywords: heat exchanger, fan hood, heat exchanger performance, air flow performance

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Authors: Md. Armin Islam, Les Dallin, Mark Boland, W. J. Zhang

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This paper reports a study on the optimal magnetic design of a compact quadrupole electromagnet for the Canadian Light Source (CLS 2.0). The nature of the design is to determine a quadrupole with low relative higher order harmonics and better field quality. The design problem was formulated as an optimization model, in which the objective function is the higher order harmonics (multipole errors) and the variable to be optimized is the material distribution on the pole. The higher order harmonics arose in the quadrupole due to truncating the ideal hyperbola at a certain point to make the pole. In this project, the arisen harmonics have been optimized both transversely and longitudinally by adjusting material on the poles in a controlled way. For optimization, finite element analysis (FEA) has been conducted. A better higher order harmonics amplitudes and field quality have been achieved through the optimization. On the basis of the optimized magnetic design, electrical and cooling calculation has been performed for the magnet.

Keywords: drift, electrical, and cooling calculation, integrated field, magnetic field gradient, multipole errors, quadrupole

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Authors: Masoud Mahdavi

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Today, developed and industrial cities have all kinds of sewage and water transfer canals, subway tunnels, infrastructure facilities, etc., which have caused underground cavities to be created under the buildings. The presence of these cavities causes behavioral changes in the structural behavior that must be fully evaluated. In the present study, using Abaqus finite element software, the effect of cavities with 0.5 and 1.5 meters in diameter at a depth of 2.5 meters from the earth's surface (with a circular cross-section) on the performance of the foundation and the ground (soil) has been evaluated. For this purpose, the Kobe earthquake was applied to the models for 10 seconds. Also, pore water pressure and weight were considered on the models to get complete results. The results showed that by creating and increasing the diameter of circular cavities in the soil, three indicators; 1) von Mises stress, 2) displacement and 3) plastic strain have had oscillating, ascending and ascending processes, respectively, which shows the relationship between increasing the diameter index of underground cavities and structural indicators of structure-foundation-soil.

Keywords: underground excavations, foundation, structural substrates, Abaqus software, Kobe earthquake, time history analysis

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Authors: Gao Youtao, Zhao Tanran, Jin Bingyu, Xu Bo

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Global navigation satellite system(GNSS) can deliver navigation information for spacecraft orbiting on low-Earth orbits and medium Earth orbits. However, the GNSS cannot navigate the spacecraft on high-Earth orbit or deep space probes effectively. With the deep space exploration becoming a hot spot of aerospace, the demand for a deep space satellite navigation system is becoming increasingly prominent. Many researchers discussed the feasibility and performance of a satellite navigation system on periodic orbits around the Earth-Moon libration points which can be called Lagrangian point satellite navigation system. Autonomous orbit determination (AOD) is an important performance for the Lagrangian point satellite navigation system. With this ability, the Lagrangian point satellite navigation system can reduce the dependency on ground stations. AOD also can greatly reduce total system cost and assure mission continuity. As the elliptical restricted three-body problem can describe the Earth-Moon system more accurately than the circular restricted three-body problem, we study the autonomous orbit determination of Lagrangian navigation constellation using only crosslink range based on elliptical restricted three body problem. Extended Kalman filter is used in the autonomous orbit determination. In order to compare the autonomous orbit determination results based on elliptical restricted three-body problem to the results of autonomous orbit determination based on circular restricted three-body problem, we give the autonomous orbit determination position errors of a navigation constellation include four satellites based on the circular restricted three-body problem. The simulation result shows that the Lagrangian navigation constellation can achieve long-term precise autonomous orbit determination using only crosslink range. In addition, the type of the libration point orbit will influence the autonomous orbit determination accuracy.

Keywords: extended Kalman filter, autonomous orbit determination, quasi-periodic orbit, navigation constellation

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Authors: Said Sair, Hanane Ait Ousaleh, Ilyas Belghazi, Othmane Amadine

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Plastic waste has become a major environmental issue, driving the need for innovative solutions to convert it into valuable resources. This study explores the catalytic pyrolysis of plastic waste to produce hydrogen, using zeolite catalysts as a key component in the process. Various zeolites, including types X, A, and P, are synthesized and characterized through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) surface area analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). These techniques are employed to assess the structural and chemical properties of the catalysts. Catalytic pyrolysis experiments are performed under different conditions, including variations in temperature, catalyst loading, and reaction time, to optimize hydrogen production. The results demonstrate that the choice of zeolite catalyst significantly impacts plastic waste conversion efficiency into hydrogen. This research contributes to advancing circular economy principles by providing an effective method for plastic waste management and clean energy production, promoting environmental sustainability.

Keywords: hydrogen production, plastic waste, zeolite catalysts, catalytic pyrolysis, circular economy, sustainable energy

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Authors: Zhidi Lei, Xixi Cai, Jue Ding, Peifen Weng, Xiaowei Li

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In the process of preparing thin films by chemical solution method, the uniformity of gel coating has a great influence on the subsequent film thickness. Based on a coating device, the research tracks the interface development of gas-liquid flow by volume of fluid method (VOF). The effects of fluid viscosity and wall wetting property for the shape and position of the coating window are discussed in the process of slot die coating. The result shows that downstream contact lines gets closer to the corner with the increase of fluid viscosity. When the viscosity increases from 0.2Pa∙s to 0.3Pa∙s, 18.2% of the vortex region area will be reduced. With the static contact angle of upper die head surface (θ_sd) increasing, X_u decreased gradually which cause the instability changes of upstream surface. Also, θ_sd increasing brings the reduction of vortex region.

Keywords: film growth, vortex, VOF, slot die coating

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Authors: Mehdi Tajdari, Farzad Mokhtarnejad, Fatemeh Moradi, Mehdi Najafizadeh

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Nowadays, energy absorbing devices have been widely used in all vehicles and moving parts such as railway couches, aircraft, ships and lifts. The aim is to protect these structures from serious damages while subjected to impact loads, or to minimize human injuries while collision is occurred in transportation systems. These energy-absorbing devices can dissipate kinetic energy in a wide variety of ways like friction, facture, plastic bending, crushing, cyclic plastic deformation and metal cutting. On the other hand, various structures may be used as collapsible energy absorbers. Metallic cylindrical tubes have attracted much more attention due to their high stiffness and strength combined with the low weight and ease of manufacturing process. As a matter of fact, favorable crash worthiness characteristics for energy dissipation purposes can be achieved from axial collapse of tubes while they crush progressively in symmetric modes. However, experimental and theoretical results have shown that depending on various parameters such as tube geometry, material properties of tube, boundary and loading conditions, circular tubes buckle in different modes of deformation, namely, diamond and Euler collapsing modes. It is shown that when the tube length is greater than the critical length, the tube deforms in overall Euler buckling mode, which is an inefficient mode of energy absorption and needs to be avoided in crash worthiness applications. This study develops a new method with the aim of improving energy absorption characteristics of long steel circular tubes. Inserting a helical spring into the tubes is proved experimentally to be an efficient solution. In fact when a long tube is subjected to axial compression load, the spring prevents of undesirable Euler or diamond collapsing modes. This is because the spring reinforces the internal wall of tubes and it causes symmetric deformation in tubes. In this research three specimens were prepared and three tests were performed. The dimensions of tubes were selected so that in axial compression load buckling is occurred. In the second and third tests a spring was inserted into tubes and they were subjected to axial compression load in quasi-static and impact loading, respectively. The results showed that in the second and third tests buckling were not happened and the tubes deformed in symmetric modes which are desirable in energy absorption.

Keywords: energy absorption, circular tubes, collapsing deformation, crashworthiness

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Authors: Norman Sinnigen, Igor Izyurov, Marina Krylova, Hamidreza Jamalabadi, Sarah Alizadeh, Martin Walter

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Background: EEG is a non-invasive brain activity recording technique with a high temporal resolution that allows the use of real-time applications, such as neurofeedback. However, EEG data are susceptible to electrooculographic (EOG) and electromyography (EMG) artifacts (i.e., jaw clenching, teeth squeezing and forehead movements). Due to their non-stationary nature, these artifacts greatly obscure the information and power spectrum of EEG signals. Many EEG artifact correction methods are too time-consuming when applied to low-density EEG and have been focusing on offline processing or handling one single type of EEG artifact. A software-only real-time method for correcting multiple types of EEG artifacts of high-density EEG remains a significant challenge. Methods: We demonstrate an improved approach for automatic real-time EEG artifact correction of EOG and EMG artifacts. The method was tested on three healthy subjects using 64 EEG channels (Brain Products GmbH) and a sampling rate of 1,000 Hz. Captured EEG signals were imported in MATLAB with the lab streaming layer interface allowing buffering of EEG data. EMG artifacts were detected by channel variance and adaptive thresholding and corrected by using channel interpolation. Real-time independent component analysis (ICA) was applied for correcting EOG artifacts. Results: Our results demonstrate that the algorithm effectively reduces EMG artifacts, such as jaw clenching, teeth squeezing and forehead movements, and EOG artifacts (horizontal and vertical eye movements) of high-density EEG while preserving brain neuronal activity information. The average computation time of EOG and EMG artifact correction for 80 s (80,000 data points) 64-channel data is 300 – 700 ms depending on the convergence of ICA and the type and intensity of the artifact. Conclusion: An automatic EEG artifact correction algorithm based on channel variance, adaptive thresholding, and ICA improves high-density EEG recordings contaminated with EOG and EMG artifacts in real-time.

Keywords: EEG, muscle artifacts, ocular artifacts, real-time artifact correction, real-time ICA

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Authors: Muhammad Haitham Albahnassi, Adnan Malki, Shokri Almekdad

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In this paper, a method for reconfiguring bandwidth in a circular dual-mode resonator is presented. The method concerns the optimized geometry of a structure that may be used to host the tuning elements, which are typically RF (Radio Frequency) switches. The tuning elements themselves, and their performance during tuning, are not the focus of this paper. The designed resonator is able to reconfigure its fractional bandwidth by adjusting the inter-coupling level between the degenerate modes, while at the same time improving its response by adjusting the external-coupling level and keeping the center frequency fixed. The inter-coupling level has been adjusted by changing the dimensions of the perturbation element, while the external-coupling level has been adjusted by changing one of the feeder dimensions. The design was arrived at via optimization. Agreeing simulation and measurement results of the designed and implemented filters showed good improvements in return loss values and the stability of the center frequency.

Keywords: dual-mode resonators, perturbation theory, reconfigurable filters, software defined radio, cognitine radio

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Authors: Matthias Feiner, Francisco Javier Fernández García, Michael Arneman, Martin Kipfmüller

Abstract:

To ensure reliability in miniaturized devices or processes with increased heat fluxes, very efficient cooling methods have to be employed in order to cope with small available cooling surfaces. To address this problem, a certain type of evaporator/heat exchanger was developed: It is called a swirl evaporator due to its flow characteristic. The swirl evaporator consists of a concentrically eroded screw geometry in which a capillary tube is guided, which is inserted into a pocket hole in components with high heat load. The liquid refrigerant R32 is sprayed through the capillary tube to the end face of the blind hole and is sucked off against the injection direction in the screw geometry. Its inner diameter is between one and three millimeters. The refrigerant is sprayed into the pocket hole via a small tube aligned in the center of the bore hole and is sucked off on the front side of the hole against the direction of injection. The refrigerant is sucked off in a helical geometry (twisted flow) so that it is accelerated against the hot wall (centrifugal acceleration). This results in an increase in the critical heat flux of up to 40%. In this way, more heat can be dissipated on the same surface/available installation space. This enables a wide range of technical applications. To optimize the design for the needs in various fields of industry, like the internal tool cooling when machining nickel base alloys like Inconel 718, a correlation-based model of the swirl-evaporator was developed. The model is separated into 3 subgroups with overall 5 regimes. The pressure drop and heat transfer are calculated separately. An approach to determine the locality of phase change in the capillary and the swirl was implemented. A test stand has been developed to verify the simulation.

Keywords: helically-shaped, oil-free, R-32, swirl-evaporator, twist-flow

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Authors: Hwan-Jun Choi, Sung-Bok Choi, Hyoung-Kyu Song

Abstract:

Recently, among the MIMO-OFDM detection techniques, a lot of papers suggested V-BLAST scheme which can achieve high data rate. Therefore, the signal detection of MIMOOFDM system is important issue. In this paper, efficient iterative VBLAST detection technique is proposed in wireless communication system. The proposed scheme adjusts the number of candidate symbol and iterative scheme based on channel state. According to the simulation result, the proposed scheme has better BER performance than conventional schemes and similar BER performance of the QRD-M with iterative scheme. Moreover complexity of proposed scheme has 50.6 % less than complexity of QRD-M detection with iterative scheme. Therefore the proposed detection scheme can be efficiently used in wireless communication.

Keywords: MIMO-OFDM, V-BLAST, QR-decomposition, QRDM, DFE, iterative scheme, channel condition

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Authors: Shamini Dhana, G. Subrahmanya VRK Rao

Abstract:

The fashion industry is advancing towards a mindset of zero waste, personalization, creativity, and circularity. The trend of upcycling clothing and materials into personalized fashion is being demanded by the next generation. There is a need for a digital tool to accelerate the process towards mass customization. Dhana’s D/Sphere fashion technology platform uses digital tools to accelerate upcycling. In essence, advanced fashion garments can be designed and developed via reuse, repurposing, recreating activities, and using existing fabric and circulating materials. The D/Sphere platform has the following objectives: to provide (1) An opportunity to develop modern fashion using existing, finished materials and clothing without chemicals or water consumption; (2) The potential for an everyday customer and designer to use the medium of fashion for creative expression; (3) A solution to address the global textile waste generated by pre- and post-consumer fashion; (4) A solution to reduce carbon emissions, water, and energy consumption with the participation of all stakeholders; (5) An opportunity for brands, manufacturers, retailers to work towards zero-waste designs and as an alternative revenue stream. Other benefits of this alternative approach include sustainability metrics, trend prediction, facilitation of disassembly and remanufacture deep learning, and hyperheuristics for high accuracy. A design tool for mass personalization and customization utilizing existing circulating materials and deadstock, targeted to fashion stakeholders will lower environmental costs, increase revenues through up to date upcycled apparel, produce less textile waste during the cut-sew-stitch process, and provide a real design solution for the end customer to be part of circular fashion. The broader impact of this technology will result in a different mindset to circular fashion, increase the value of the product through multiple life cycles, find alternatives towards zero waste, and reduce the textile waste that ends up in landfills. This technology platform will be of interest to brands and companies that have the responsibility to reduce their environmental impact and contribution to climate change as it pertains to the fashion and apparel industry. Today, over 70% of the $3 trillion fashion and apparel industry ends up in landfills. To this extent, the industry needs such alternative techniques to both address global textile waste as well as provide an opportunity to include all stakeholders and drive circular fashion with new personalized products. This type of modern systems thinking is currently being explored around the world by the private sector, organizations, research institutions, and governments. This technological innovation using digital tools has the potential to revolutionize the way we look at communication, capabilities, and collaborative opportunities amongst stakeholders in the development of new personalized and customized products, as well as its positive impacts on society, our environment, and global climate change.

Keywords: circular fashion, deep learning, digital technology platform, personalization

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Authors: Maria Areias, Diogo Simões, Ana Figueiredo, Anishur Rahman, Filipa Figueiredo, João Nunes

Abstract:

It is expected that close to 7 billion people will live in urban areas by 2050. In order to improve the sustainability of the territories and its transition towards circular economy, it’s necessary to understand its metabolism and promote and guide the entrepreneurship answer. The study of a macroeconomic metabolism involves the quantification of the inputs, outputs and storage of energy, water, materials and wastes for an urban region. This quantification and analysis representing one opportunity for the promotion of green entrepreneurship. There are several methods to assess the environmental impacts of an urban territory, such as human and environmental risk assessment (HERA), life cycle assessment (LCA), ecological footprint assessment (EF), material flow analysis (MFA), physical input-output table (PIOT), ecological network analysis (ENA), multicriteria decision analysis (MCDA) among others. However, no consensus exists about which of those assessment methods are best to analyze the sustainability of these complex systems. Taking into account the weaknesses and needs identified, the CiiM - Circular Innovation Inter-Municipality project aims to define an uniform and globally accepted methodology through the integration of various methodologies and dynamic approaches to increase the efficiency of macroeconomic metabolisms and promoting entrepreneurship in a circular economy. The pilot territory considered in CiiM project has a total area of 969,428 ha, comprising a total of 897,256 inhabitants (about 41% of the population of the Center Region). The main economic activities in the pilot territory, which contribute to a gross domestic product of 14.4 billion euros, are: social support activities for the elderly; construction of buildings; road transport of goods, retailing in supermarkets and hypermarkets; mass production of other garments; inpatient health facilities; and the manufacture of other components and accessories for motor vehicles. The region's business network is mostly constituted of micro and small companies (similar to the Central Region of Portugal), with a total of 53,708 companies identified in the CIM Region of Coimbra (39 large companies), 28,146 in the CIM Viseu Dão Lafões (22 large companies) and 24,953 in CIM Beiras and Serra da Estrela (13 large companies). For the construction of the database was taking into account data available at the National Institute of Statistics (INE), General Directorate of Energy and Geology (DGEG), Eurostat, Pordata, Strategy and Planning Office (GEP), Portuguese Environment Agency (APA), Commission for Coordination and Regional Development (CCDR) and Inter-municipal Community (CIM), as well as dedicated databases. In addition to the collection of statistical data, it was necessary to identify and characterize the different stakeholder groups in the pilot territory that are relevant to the different metabolism components under analysis. The CIIM project also adds the potential of a Geographic Information System (GIS) so that it is be possible to obtain geospatial results of the territorial metabolisms (rural and urban) of the pilot region. This platform will be a powerful visualization tool of flows of products/services that occur within the region and will support the stakeholders, improving their circular performance and identifying new business ideas and symbiotic partnerships.

Keywords: circular economy tools, life cycle assessment macroeconomic metabolism, multicriteria decision analysis, decision support tools, circular entrepreneurship, industrial and regional symbiosis

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Authors: Khalid Iqbal, Saima Altaf, M. Akram, Muhammad Abdur Rafaye, Saeed Ahmad Buzdar

Abstract:

Objective: Verification of patient-specific intensity modulated radiation therapy (IMRT) plans using different 2-D detectors has become increasingly popular due to their ease of use and immediate readout of the results. The purpose of this study was to test and compare various 2-D detectors for dosimetric quality assurance (QA) of intensity-modulated radiotherapy (IMRT) with the vision to find alternative QA methods. Material and Methods: Twenty IMRT patients (12 of brain and 8 of the prostate) were planned on Eclipse treatment planning system using Varian Clinac DHX on both energies 6MV and 15MV. Verification plans of all such patients were also made and delivered to Map check2, EPID (Electronic portal imaging device) and Gafchromic EBT3. Gamma index analyses were performed using different criteria to evaluate and compare the dosimetric results. Results: Statistical analysis shows the passing rate of 99.55%, 97.23% and 92.9% for 6MV and 99.53%, 98.3% and 94.85% for 15 MV energy using a criteria of ±5% of 3mm, ±3% of 3mm and ±3% of 2mm respectively for brain, whereas using ±5% of 3mm and ±3% of 3mm gamma evaluation criteria, the passing rate is 94.55% and 90.45% for 6MV and 95.25%9 and 95% for 15 MV energy for the case of prostate using EBT3 film. Map check 2 results shows the passing rates of 98.17%, 97.68% and 86.78% for 6MV energy and 94.87%,97.46% and 88.31% for 15 MV energy respectively for brain using a criteria of ±5% of 3mm, ±3% of 3mm and ±3% of 2mm, whereas using ±5% of 3mm and ±3% of 3mm gamma evaluation criteria gives the passing rate of 97.7% and 96.4% for 6MV and 98.75%9 and 98.05% for 15 MV energy for the case of prostate. EPID 6 MV and gamma analysis shows the passing rate of 99.56%, 98.63% and 98.4% for the brain, 100% and 99.9% for prostate using the same criteria as for map check 2 and EBT 3 film. Conclusion: The results demonstrate excellent passing rates were obtained for all dosimeter when compared with the planar dose distributions for 6 MV IMRT fields as well as for 15 MV. EPID results are better than EBT3 films and map check 2 because it is likely that part of this difference is real, and part is due to manhandling and different treatment set up verification which contributes dose distribution difference. Overall all three dosimeter exhibits results within limits according to AAPM report.120.

Keywords: gafchromic EBT3, radiochromic film dosimetry, IMRT verification, EPID

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Authors: Chen Jun-Hong, He Pu, Tao Wen-Quan

Abstract:

Proton exchange membrane fuel cell (PEMFC) is the most promising future energy source owing to its low operating temperature, high energy efficiency, high power density, and environmental friendliness. In this paper, a comprehensive PEMFC system control-oriented model is developed in the Matlab/Simulink environment, which includes the hydrogen supply subsystem, air supply subsystem, and thermal management subsystem. Besides, Improved Artificial Bee Colony (IABC) is used in the parameter identification of PEMFC semi-empirical equations, making the maximum relative error between simulation data and the experimental data less than 0.4%. Operation temperature is essential for PEMFC, both high and low temperatures are disadvantageous. In the thermal management subsystem, water pump and fan are both controlled with the PID controller to maintain the appreciate operation temperature of PEMFC for the requirements of safe and efficient operation. To improve the control effect further, fuzzy control is introduced to optimize the PID controller of the pump, and the Radial Basis Function (RBF) neural network is introduced to optimize the PID controller of the fan. The results demonstrate that Fuzzy-PID and RBF-PID can achieve a better control effect with 22.66% decrease in Integral Absolute Error Criterion (IAE) of T_st (Temperature of PEMFC) and 77.56% decrease in IAE of T_in (Temperature of inlet cooling water) compared with traditional PID. In the end, a novel thermal management structure is proposed, which uses the cooling air passing through the main radiator to continue cooling the secondary radiator. In this thermal management structure, the parasitic power dissipation can be reduced by 69.94%, and the control effect can be improved with a 52.88% decrease in IAE of T_in under the same controller.

Keywords: PEMFC system, parameter identification, temperature control, Fuzzy-PID, RBF-PID, parasitic power

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Authors: Megha Ramnik Kotecha

Abstract:

To study whether there is any clinical correlation between pterygium and dry eye and to evaluate the status of tear film in patients with pterygium. Methods: 100 eyes with pterygium were compared with 100 control eyes without pterygium. Patients between 20 – 70 years were included in the study. Detailed history was taken and Schirmer’s test and TBUT were performed on all to evaluate the status of dry eye. Schirmer’s test ˂10 mm and TBUT ˂10 seconds was considered abnormal. Results: Maximum number (52) of patients affected with dry eye in both the groups were in the age group 31-40 years which statistically showed age as a significant factor of association for both pterygium and dry eye (P<0.01).Schirmer’s test was slightly reduced in patients with pterygium(18.73±5.69 mm). TBUT was significantly reduced in the case group (12.26±2.24sec).TBUT decreased maximally in 51-60 yrs age group (13.00±2.77sec) with pterygium showing a tear film unstability. On comparision of pterygia and controls with normal and abnormal tear film, Odd’s Ratio was 1.14 showing risk of dry eye in pterygia patients to be 1.14 times higher than controls. Conclusion: Whether tear dysfunction is a precursor to pterygium growth or pterygium causes tear dysfunction is still not clear. Research and clinical evidence, however, suggest that there is a relationship between the two. This study is, therefore, undertaken to investigate the correlation between pterygium and dry eye. The patients with pterygia were compared with normals to evaluate their status regarding dryness. A close relationship exists between ocular irritation symptoms and functional evidence of tear instability. Schirmer’s test and TBUT should routinely be used in the outpatient department to diagnose dry eye in patients with pterygium and these patients should be promptly treated to prevent any sight threatening complications.

Keywords: dry eye, pterygium, Schirmer's test, tear break up time (TBUT)

Procedia PDF Downloads 300