Search results for: composite frame structure

Authors: Piotr Kunecki, Magdalena Wdowin

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The fly ash produced as waste in the process of conventional coal combustion was utilized in the hybrid synthesis of zeolites X and A from Faujasite (FAU) and Linde Type A (LTA) frameworks, respectively. The applied synthesis method included modification together with the crystallization stage. The sorbent modification was performed by introducing metals into the zeolite structure in order to create an ability to form stable bonds with elemental mercury (Hg0). The use of waste in the form of fly ash as a source of silicon and aluminum, as well as the proposed method of zeolite synthesis, fits the circular economy idea. The effect of zeolite modification on Hg0 removal from a simulated gas stream was studied empirically using prototype installation designed to test the effectiveness of sorption by solid-state sorbents. Both derived zeolites X and A modified with silver nitrate revealed significant mercury uptake during a 150-minute sorption experiment. The amount of elemental mercury removed in the experiment ranged from 5.69 to 6.01 µg Hg0/1g of sorbent for zeolites X and from 4.47 to 4.86 µg Hg0/1g of sorbent for zeolites A. In order to confirm the effectiveness of the sorbents towards mercury bonding, the possible re-emission effect was tested as well. Derived zeolites X and A did not show mercury re-emission after the sorption process, which confirms the stable bonding of Hg0 in the structure of synthesized zeolites. The proposed hybrid synthesis method possesses the potential to be implemented for both fly ash utilization as well as the time and energy-saving production of aluminosilicate, porous materials with high Hg0 removal efficiency. This research was supported by National Science Centre, Poland, grant no 2021/41/N/ST5/03214.

Keywords: fly ash, synthetic zeolites, elemental mercury removal, sorption, simulated gas stream

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Authors: Joshua Loiselle

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This paper discusses the challenges engineering teams face in conducting Failure Modes and Effects Analysis (FMEA) studies. This paper focuses on the specific topic of improving the efficiency and effectiveness of FMEA studies. Modern economic needs and increased business competition require engineers to constantly develop newer and better solutions within shorter timeframes and tighter margins. In addition, documentation requirements for meeting standards/regulatory compliance and customer needs are becoming increasingly complex and verbose. Managing open actions and continuous improvement activities across all projects, product variations, and processes in addition to daily engineering tasks is cumbersome, time consuming, and is susceptible to errors, omissions, and non-conformances. FMEA studies are proven methods for improving products and processes while subsequently reducing engineering workload and improving machine and resource availability through a pre-emptive, systematic approach of identifying, analyzing, and improving high-risk components. If implemented correctly, FMEA studies significantly reduce costs and improve productivity. However, the value of an effective FMEA is often shrouded by a lack of clarity and structure, misconceptions, and previous experiences and, as such, FMEA studies are frequently grouped with the other required information and documented retrospectively in preparation of customer requirements or audits. Performing studies in this way only adds cost to a project and perpetuates the misnomer that FMEA studies are not value-added activities. This paper discusses the benefits of effective FMEA studies, the challenges related to conducting FMEA studies, best practices for efficiently overcoming challenges via structure and automation, and the benefits of implementing those practices.

Keywords: FMEA, quality, APQP, PPAP

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Authors: Claudio Calosi, Damiano Costa, Paolo Natali

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Determination is the relation that holds between certain kinds of properties, determinables – such as “being colored”, and others, determinates – such as “being red”. Subordination is the relation that holds between genus properties – such as “being an animal”, and others, species properties – such as “being human”'. It is widely held that Determination and Subordination share important similarities, yet also crucial differences. But what grounds such similarities and differences? This question is hardly ever addressed. The present paper provides the first step towards filling this gap in the literature. It argues that a locational theory of instantiation, roughly the view that to have a property is to occupy a location in quality space, holds the key for such an answer. More precisely, it argues that both principles of Determination and Subordination are just examples of more general principles of location. Consider Determination. The principle that everything that has a determinate has a determinable boils down to the claim that everything that has a precise location in quality space is in quality space – an eminently reasonable principle. The principle that nothing can have two determinates (at the same level of determination) boils down to the principle that nothing can be “multilocated” in quality space. In effect, the following provides a “translation table” between principles of location and determination: LOCATION DETERMINATION Functionality At Most One Determination Focus At Most One Determination & Requisite Determination* Exactness Requisite Determination* Super-Exactness Requisite Determination Exactitude Requisite Determination Converse-Exactness Determinable Inehritance This grounds the similarity between Determination and Subordination. What about the differences? The paper argues that the differences boil down to the mereological structure of the regions that are occupied in quality space, in particular whether they are simple or complex. The key technical detail is that Determination and Subordination induce a “set-theoretic rooted tree” structure over the domain of properties. Interestingly, the analysis also provides a possible justification for the Aristotelian claim that being is not a genus property – an argument that the paper develops in some detail.

Keywords: determinables/determinates, genus/species, location, Aristotle on being is not a genus

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Authors: I. Nitoi, P. Oancea, M. Raileanu, M. Crisan, L. Constantin, I. Cristea

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Hazardous organic compounds like nitroaromatics are frequently found in chemical and petroleum industries discharged effluents. Due to their bio-refractory character and high chemical stability cannot be efficiently removed by classical biological or physical-chemical treatment processes. In the past decades, semiconductor photocatalysis has been frequently applied for the advanced degradation of toxic pollutants. Among various semiconductors titania was a widely studied photocatalyst, due to its chemical inertness, low cost, photostability and nontoxicity. In order to improve optical absorption and photocatalytic activity of TiO2 many attempts have been made, one feasible approach consists of doping oxide semiconductor with metal. The degradation of dinitrobenzene (DNB) and dinitrotoluene (DNT) from aqueous solution under UVA-VIS irradiation using heavy metal (0.5% Fe, 1%Co, 1%Ni ) doped titania was investigated. The photodegradation experiments were carried out using a Heraeus laboratory scale UV-VIS reactor equipped with a medium-pressure mercury lamp which emits in the range: 320-500 nm. Solutions with (0.34-3.14) x 10-4 M pollutant content were photo-oxidized in the following working conditions: pH = 5-9; photocatalyst dose = 200 mg/L; irradiation time = 30 – 240 minutes. Prior to irradiation, the photocatalyst powder was added to the samples, and solutions were bubbled with air (50 L/hour), in the dark, for 30 min. Dopant type, pH, structure and initial pollutant concentration influence on the degradation efficiency were evaluated in order to set up the optimal working conditions which assure substrate advanced degradation. The kinetics of nitroaromatics degradation and organic nitrogen mineralization was assessed and pseudo-first order rate constants were calculated. Fe doped photocatalyst with lowest metal content (0.5 wt.%) showed a considerable better behaviour in respect to pollutant degradation than Co and Ni (1wt.%) doped titania catalysts. For the same working conditions, degradation efficiency was higher for DNT than DNB in accordance with their calculated adsobance constants (Kad), taking into account that degradation process occurs on catalyst surface following a Langmuir-Hinshalwood model. The presence of methyl group in the structure of DNT allows its degradation by oxidative and reductive pathways, while DNB is converted only by reductive route, which also explain the highest DNT degradation efficiency. For highest pollutant concentration tested (3 x 10-4 M), optimum working conditions (0.5 wt.% Fe doped –TiO2 loading of 200 mg/L, pH=7 and 240 min. irradiation time) assures advanced nitroaromatics degradation (ηDNB=89%, ηDNT=94%) and organic nitrogen mineralization (ηDNB=44%, ηDNT=47%).

Keywords: hazardous organic compounds, irradiation, nitroaromatics, photocatalysis

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Authors: Carlos H. Cuadra, Nobuhiro Shimoi

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Application of piezoelectric sensors to detect structural damage due to seismic action on building structures is investigated. Plate-type piezoelectric sensor was developed and proposed for this task. A film-type piezoelectric sheet was attached on a steel plate and covered by a layer of glass. A special glue is used to fix the glass. This glue is a silicone that requires the application of ultraviolet rays for its hardening. Then, the steel plate was set up at a steel column-beam joint of a test specimen that was subjected to bending moment when test specimen is subjected to monotonic load and cyclic load. The structural behavior of test specimen during cyclic loading was verified using a finite element model, and it was found good agreement between both results on load-displacement characteristics. The cross section of steel elements (beam and column) is a box section of 100 mm×100 mm with a thin of 6 mm. This steel section is specified by the Japanese Industrial Standards as carbon steel square tube for general structure (STKR400). The column and beam elements are jointed perpendicularly using a fillet welding. The resulting test specimen has a T shape. When large deformation occurs the glass plate of the sensor device cracks and at that instant, the piezoelectric material emits a voltage signal which would be the indicator of a certain level of deformation or damage. Applicability of this piezoelectric sensor to detect structural damages was verified; however, additional analysis and experimental tests are required to establish standard parameters of the sensor system.

Keywords: piezoelectric sensor, static cyclic test, steel structure, seismic damages

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Authors: Evrim Colak, Andriy E. Serebryannikov, Pavel V. Usik, Ekmel Ozbay

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Working with a dielectric photonic crystal (PC) structure which does not include surface corrugations, unidirectional transmission and dual-beam splitting are observed under normal incidence as a result of the strong diffractions caused by the embedded defect layer. The defect layer has twice the period of the regular PC segments which sandwich the defect layer. Although the PC has even number of rows, the structural symmetry is broken due to the asymmetric placement of the defect layer with respect to the symmetry axis of the regular PC. The simulations verify that efficient splitting and occurrence of strong diffractions are related to the dispersion properties of the Floquet-Bloch modes of the photonic crystal. Unidirectional and bi-directional splitting, which are associated with asymmetric transmission, arise due to the dominant contribution of the first positive and first negative diffraction orders. The effect of the depth of the defect layer is examined by placing single defect layer in varying rows, preserving the asymmetry of PC. Even for deeply buried defect layer, asymmetric transmission is still valid even if the zeroth order is not coupled. This transmission is due to evanescent waves which reach to the deeply embedded defect layer and couple to higher order modes. In an additional selected performance, whichever surface is illuminated, i.e., in both upper and lower surface illumination cases, incident beam is split into two beams of equal intensity at the output surface where the intensity of the out-going beams are equal for both illumination cases. That is, although the structure is asymmetric, symmetric bidirectional transmission with equal transmission values is demonstrated and the structure mimics the behavior of symmetric structures. Finally, simulation studies including the examination of a coupled-cavity defect for two different permittivity values (close to the permittivity values of GaAs or Si and alumina) reveal unidirectional splitting for a wider band of operation in comparison to the bandwidth obtained in the case of a single embedded defect layer. Since the dielectric materials that are utilized are low-loss and weakly dispersive in a wide frequency range including microwave and optical frequencies, the studied structures should be scalable to the mentioned ranges.

Keywords: asymmetric transmission, beam deflection, blazing, bi-directional splitting, defect layer, dual beam splitting, Floquet-Bloch modes, isofrequency contours, line defect, oblique incidence, photonic crystal, unidirectionality

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Authors: U. P. L. Wijayarathne, P. W. Vidanage, H. K. D. Jayampath, K. W. P. M. Kothalawala

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Feasibility of utilizing Empty Bunch (EB) fibre, a solid waste of palm oil extraction process, as an adsorbent is analysed in this study. Empty bunch fibre is generated after the extraction of retained oil in the sterilized and threshed empty fruit bunches. Besides the numerous characteristics of EB fibre, which enable its utilization as a fuel, a bio-composite material, or mulch, EB fibre also shows exceptional characteristics of a good adsorbent. Fixed bed adsorption method is used to study the adsorptivity of EB fibre using a continuous adsorption column with Methyl-blue (1.13ppm) as the feed. Adsorptivity is assumed to be solely dependent on the bed porosity keeping other parameters (feed flow rate, bed height, bed diameter, and operating temperature) constant. Bed porosity is changed by means of compact ratio and the variation of the feed concentration is analysed using a photometric method. Break through curves are plotted at different porosity levels and optimum bed porosity is identified for a given feed stream. Feasibility of using the EB fibre as an inexpensive and an abundant adsorbent in wastewater treatment facilities, where the effluent colour reduction is adamant, is also discussed.

Keywords: adsorption, fixed bed, break through time, methylene blue, oil palm fibre

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Authors: Henrry Vicente Rojas Asuero, Holger Manuel Benavides Muñoz

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Approximately 80% of the energy consumed worldwide is generated from fossil sources, which are responsible for the emission of a large volume of greenhouse gases. For this reason, the global trend, at present, is the widespread use of energy produced from renewable sources. This seeks safety and diversification of energy supply, based on social cohesion, economic feasibility and environmental protection. In this scenario, small hydropower systems (P ≤ 10MW) stand out due to their high efficiency, economic competitiveness and low environmental impact. Small hydropower systems, along with wind and solar energy, are expected to represent a significant percentage of the world's energy matrix in the near term. Among the various technologies present in the state of the art, relating to small hydropower systems, is the Gravitational Water Vortex Power Plant, a recent technology that excels because of its versatility of operation, since it can operate with jumps in the range of 0.70 m-2.00 m and flow rates from 1 m3/s to 20 m3/s. Its operating system is based on the utilization of the energy of rotation contained within a large water vortex artificially induced. This paper presents the study and experimental design of an optimal hydraulic structure with the capacity to induce the artificial formation of a gravitational water vortex trough a system of easy application and high efficiency, able to operate in conditions of very low head and minimum flow. The proposed structure consists of a channel, with variable base, vortex inductor, tangential flow generator, coupled to a circular tank with a conical transition bottom hole. In the laboratory test, the angular velocity of the water vortex was related to the geometric characteristics of the inductor channel, as well as the influence of the conical transition bottom hole on the physical characteristics of the water vortex. The results show angular velocity values of greater magnitude as a function of depth, in addition the presence of the conical transition in the bottom hole of the circular tank improves the water vortex formation conditions while increasing the angular velocity values. Thus, the proposed system is a sustainable solution for the energy supply of rural areas near to watercourses.

Keywords: experimental model, gravitational water vortex power plant, renewable energy, small hydropower

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Authors: S. B. Rathna Kumar, Pranjali A Ujwane, Panchanan Mohanty

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The present study aimed to develop a battery for assessing speech recognition performance by adults in Marathi. A total of four word lists were developed by considering word frequency, word familiarity, words in common use, and phonemic balance. Each word list consists of 25 words (15 monosyllabic words in CVC structure and 10 monosyllabic words in CVCV structure). Equivalence analysis and performance-intensity function testing was carried using the four word lists on a total of 150 native speakers of Marathi belonging to different regions of Maharashtra (Vidarbha, Marathwada, Khandesh and Northern Maharashtra, Pune, and Konkan). The subjects were further equally divided into five groups based on above mentioned regions. It was found that there was no significant difference (p > 0.05) in the speech recognition performance between groups for each word list and between word lists for each group. Hence, the four word lists developed were equally difficult for all the groups and can be used interchangeably. The performance-intensity (PI) function curve showed semi-linear function, and the groups’ mean slope of the linear portions of the curve indicated an average linear slope of 4.64%, 4.73%, 4.68%, and 4.85% increase in word recognition score per dB for list 1, list 2, list 3 and list 4 respectively. Although, there is no data available on speech recognition tests for adults in Marathi, most of the findings of the study are in line with the findings of research reports on other languages. The four word lists, thus developed, were found to have sufficient reliability and validity in assessing speech recognition performance by adults in Marathi.

Keywords: speech recognition performance, phonemic balance, equivalence analysis, performance-intensity function testing, reliability, validity

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Authors: Sharan K. Indrakar, Aakash B. Prasad, Arash Takshi, Sesha Srinivasan, Elias K. Stefanakos

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In this work, we present an exclusive study on the effect of the feeding ratio of polyaniline-based redox-active gel layer on electrical and optical properties of innovative electrochromic devices (ECs). An electrochromic device consisting of polyaniline (PANI) has a redox-active gel electrolyte placed between two conducting transparent fluorine-doped tin oxide glass substrates. The redox-active composite gel is a mixture of different concentrations of aniline (monomer), a water-soluble polymer poly (vinyl alcohol), hydrochloric acid, and an oxidant. The EC device shows the color change from dark green to transparent for the applied potential between -0.5 V to +2.0 V. The coloration and decoloration of the ECs were tested for electrochemical behavior using techniques such as cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The optical transparency of the EC devices was examined at two different biasing voltage conditions under UV-visible spectroscopic technique; the result showed 65% transmittance at 564 nm and zero transmittance when the cell was biased at 0.0 V and 2.0 V, the synthesized mol fraction gel was analyzed for surface morphology and structural properties by scanning electron microscopy and Fourier transformer spectroscopy.

Keywords: electrochromic, gel electrolyte, polyaniline, conducting polymer

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Authors: Rehan Waheed, Hasan Aftab Saeed, Wasim Tarar, Khalid Mahmood, Sajid Ullah Butt

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Electromagnetic Interference (EMI) shielded doors made from brass extruded channels need to be welded with shielded enclosures to attain optimum shielding performance. Control of welding induced distortion is a problem in welding dissimilar metals like steel and brass. In this research, soldering of the steel-brass joint has been proposed to avoid weld distortion. The material used for brass channel is UNS C36000. The thickness of brass is defined by the manufacturing process, i.e. extrusion. The thickness of shielded enclosure material (ASTM A36) can be varied to produce joint between the dissimilar metals. Steel sections of different gauges are soldered using (91% tin, 9% zinc) solder to the brass, and strength of joint is measured by standard test procedures. It is observed that thin steel sheets produce a stronger bond with brass. The steel sections further require to be welded with shielded enclosure steel sheets through TIG welding process. Stresses and deformation in the vicinity of soldered portion is calculated through FE simulation. Crack formation in soldered area is also studied through experimental work. It has been found that in thin sheets deformation produced due to applied force is localized and has no effect on soldered joint area whereas in thick sheets profound cracks have been observed in soldered joint. The shielding effectiveness of EMI shielded door is compromised due to these cracks. The shielding effectiveness of the specimens is tested and results are compared.

Keywords: dissimilar metal, EMI shielding, joint strength, soldering

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Authors: Shruti Malviya, Chris Bowler

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Environmental processes acting at multiple spatial scales control marine diatom community structure. However, the contribution of local factors (e.g., temperature, salinity, etc.) in these highly complex systems is poorly understood. We, therefore, investigated the diatom community organization as a function of environmental predictors and determined the relative contribution of various environmental factors on the structure of marine diatoms assemblages in the world’s ocean. The dataset for this study was derived from the Tara Oceans expedition, constituting 46 sampling stations from diverse oceanic provinces. The V9 hypervariable region of 18s rDNA was organized into assemblages based on their distributional co-occurrence. Using Ward’s hierarchical clustering, nine clusters were defined. The number of ribotypes and reads varied within each cluster-three clusters (II, VIII and IX) contained only a few reads whereas two of them (I and IV) were highly abundant. Of the nine clusters, seven can be divided into two categories defined by a positive correlation with phosphate and nitrate and a negative correlation with longitude and, the other by a negative correlation with salinity, temperature, latitude and positive correlation with Lyapunov exponent. All the clusters were found to be remarkably dominant in South Pacific Ocean and can be placed into three classes, namely Southern Ocean-South Pacific Ocean clusters (I, II, V, VIII, IX), South Pacific Ocean clusters (IV and VII), and cosmopolitan clusters (III and VI). Our findings showed that co-occurring ribotypes can be significantly associated into recognizable clusters which exhibit a distinct response to environmental variables. This study, thus, demonstrated distinct behavior of each recognized assemblage displaying a taxonomic and environmental signature.

Keywords: assemblage, diatoms, hierarchical clustering, Tara Oceans

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Authors: Tien Hui Chiang

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Along with the predominant influence of neo-liberalism, public managerialism is viewed as a panacea for curing the institutionalized weakness caused by the monopoly of the public sector. In the name of efficiency, its outcome-led approach acquires a legitimate status and, in turn, it transforms into the discourse of performativity, reformulating the souls of individual members into the form of docile bodies who are willing to demonstrate their own ability in organizational contributions. The evaluation system and the organizational reconstruction are viewed as the crucial means for achieving this mission. Inevitably, university teachers are confined within a rigid and bureaucratic setting, in which they do not have too much latitude but are subject to the commands of senior administrators. However, the notion of duality highlights the interaction between structural constraints and agency. If the actor discovers the rules or properties of social structure, he/she is able to transform structural constraints into resources for developing creative actions, conceptualized as an agency. This study was designed for examining how duality operates within this hierarchical arrangement formed by public managerialism. Fourteen informants were interviewed from February to August 2014. The findings show that the evaluation system created the culture of neo-academicalism, addressing excellence in research and, in turn, motivating academic-oriented teachers. This correspondence provided a gateway for them to win honor, dignity, and prestige in groups. However, unlike the concept of duality, this agency was operating within the institutionalized context, regulated by structural constraint. Furthermore, complying with the rule/property of social structure was able to secure their advantages.

Keywords: public managerialism, social discourse, neo-academicalism, duality, structural constraint, agency

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Authors: Dalila Hammiche, Lisa Klaai, Amar Boukerrou

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Following this trend, natural fiber reinforcements have been gaining importance in the composites sector. The effectiveness of natural fiber–reinforced PLA composite as an alternative material to substitute the non-renewable petroleum-based materials has been examined by researchers. In this study, we investigated the physicochemical, particle size and distribution, and thermal behavior of prickly pear seed flour (PPSF). Then, composites were manufactured with 20% in PPSF. Thermal, morphological, and mechanical properties have been studied, and water absorption tests as well. The characterization of this fiber has shown that cellulose is the majority constituent (30%), followed by hemicellulose (27%). To improve the fiber-matrix adhesion, the PPS was chemically treated with alkali treatment. The addition of PPSF decreases the thermal properties, and the study of the mechanical properties showed that the increase in the fiber content from 0 to 20% increased Young’s modulus. According to the results, the mechanical and thermal behaviors of composites are improved after fiber treatment. However, there is an increase in water absorption of composites compared to the PLA matrix. The moisture sensitivity of natural fiber composites limits their use in structural applications. Degradation of the fiber-matrix interface is likely to occur when the material is subjected to variable moisture conditions.

Keywords: biopolymer, composites, alcali treatment, mechanical properties

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Authors: Kimuel Suyat, Francis Aldrine Uy, John Paul Carreon

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The Philippines, composed of many islands, is connected with approximately 8030 bridges. Continuous evaluation of the structural condition of these bridges is needed to safeguard the safety of the general public. With most bridges reaching its design life, retrofitting and replacement may be needed. Concerned government agencies allocate huge costs for periodic monitoring and maintenance of these structures. The rising volume of traffic and aging of these infrastructures is challenging structural engineers to give rise for structural health monitoring techniques. Numerous techniques are already proposed and some are now being employed in other countries. Vibration Analysis is one way. The natural frequency and vibration of a bridge are design criteria in ensuring the stability, safety and economy of the structure. Its natural frequency must not be so high so as not to cause discomfort and not so low that the structure is so stiff causing it to be both costly and heavy. It is well known that the stiffer the member is, the more load it attracts. The frequency must not also match the vibration caused by the traffic loads. If this happens, a resonance occurs. Vibration that matches a systems frequency will generate excitation and when this exceeds the member’s limit, a structural failure will happen. This study presents a method for calculating dynamic fragility through the use of vibration-based monitoring system. Dynamic fragility is the probability that a structural system exceeds a limit state when subjected to dynamic loads. The bridge is modeled in SAP2000 based from the available construction drawings provided by the Department of Public Works and Highways. It was verified and adjusted based from the actual condition of the bridge. The bridge design specifications are also checked using nondestructive tests. The approach used in this method properly accounts the uncertainty of observed values and code-based structural assumptions. The vibration response of the structure due to actual loads is monitored using installed sensors on the bridge. From the determinacy of these dynamic characteristic of a system, threshold criteria can be established and fragility curves can be estimated. This study conducted in relation with the research project between Department of Science and Technology, Mapúa Institute of Technology, and the Department of Public Works and Highways also known as Mapúa-DOST Smart Bridge Project deploys Structural Health Monitoring Sensors at Zamora Bridge. The bridge is selected in coordination with the Department of Public Works and Highways. The structural plans for the bridge are also readily available.

Keywords: structural health monitoring, dynamic characteristic, threshold criteria, traffic loads

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Authors: Subhasisa Nath, David Waugh, Graham Ormondroyd, Morwenna Spear, Andy Pitman, Paul Mason

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Wood is one of the most sustainable and environmentally favourable materials and is chemically treated in timber industries to maximise durability. To increase the chemical preservative uptake and retention by the wood, current limiting incision technologies are commonly used. This work reports the effects of single pulse CO2 laser-incision and frequency tripled Nd:YAG percussion laser-incision on the characteristics of laser-incised holes in the Radiata Pine. The laser-incision studies were based on changing laser wavelengths, energies and focal planes to conclude on an optimised combination for the laser-incision of Radiata Pine. The laser pulse duration had a dominant effect over laser power in controlling hole aspect ratio in CO2 laser-incision. A maximum depth of ~ 30 mm was measured with a laser power output of 170 W and a pulse duration of 80 ms. However, increased laser power led to increased carbonisation of holes. The carbonisation effect was reduced during laser-incision in the ultra-violet (UV) regime. Deposition of a foamy phase on the laser-incised hole wall was evident irrespective of laser radiation wavelength and energy. A maximum hole depth of ~20 mm was measured in the percussion laser-incision in the UV regime (355 nm) with a pulse energy of 320 mJ. The radial and tangential faces had a significant effect on laser-incision efficiency for all laser wavelengths. The laser-incised hole shapes and circularities were affected by the wood anatomy (earlywoods and latewoods in the structure). Subsequently, the mechanism of laser-incision is proposed by analysing the internal structure of laser-incised holes.

Keywords: CO2 Laser, Nd: YAG laser, incision, drilling, wood, hole characteristics

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Authors: J. N. Anene, A. A. Bello, C. C. Anene

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The paper carried out a comparative study of the challenges of e-learning in Nigerian universities. The purpose of the study was to determine if there was a significant difference in the challenges faced by students in e-learning in Nigerian Universities. A total of two hundred and twenty-eight students from nine universities constituted the sample for the study. A simple random sampling technique was employed in selecting thirty–two students from one of each university in the six geo-political zones of Nigeria. The questionnaire based on 'yes or no' and column charts constituted the instrument employed in the study. Percentages were used to analyse 'yes or no' while column charts were used to compare responds of the students. The finding of the study revealed that majority of students in all the universities under study claimed that their universities lacked appropriate software, that good quality educational content online was lacking, they also agreed that sustainability of e-learning was not prioritized, that they had no access to appropriate content for ICT-enhanced learning and training and that they had access to affordable and reliable computers. For lecturers, the computer certification should be the first on the list of promotion requirements. The finding of the study revealed that students from seven out of nine universities confirmed that their universities lack of appropriate software whereas the other two claimed that they have appropriate software. Also, out of nine universities, two disagreed to the fact that good quality educational content online lacked, whereas seven agreed that they lacked good quality educational content online. The finding of the study also revealed that most of the respondents in almost all the university under study agreed that sustainability of e-learning was not prioritized. The study recommended among other that the Nigerian Government should make concerted effort to provide the enablement for all lecturers and students to become computer literate. This should be done within a time frame, and at the end of the computer course, certificates should be issued, and no student should graduate in his or her field of study without passing the computer course.

Keywords: e-learning, developing countries, computer literacy, ICT

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Authors: Travis Morris

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The purpose of this study is to measure the intersection of environmental security entities in terrorist propaganda. To the best of author’s knowledge, this is the first study of its kind to examine this intersection within terrorist propaganda. Rosoka, natural language processing software and frame analysis are used to advance our understanding of how environmental frames function as emotive triggers. Violent jihadi demagogues use frames to suggest violent and non-violent solutions to their grievances. Emotive triggers are framed in a way to leverage individual and collective attitudes in psychological warfare. A comparative research design is used because of the differences and similarities that exist between two variants of violent jihadi propaganda that target western audiences. Analysis is based on salience and network text analysis, which generates violent jihadi semantic networks. Findings indicate that environmental frames are used as emotive triggers across both data sets, but also as tactical and information data points. A significant finding is that certain core environmental emotive triggers like “water,” “soil,” and “trees” are significantly salient at the aggregate level across both data sets. All environmental entities can be classified into two categories, symbolic and literal. Importantly, this research illustrates how demagogues use environmental emotive triggers in cyber space from a subcultural perspective to mobilize target audiences to their ideology and praxis. Understanding the anatomy of propaganda construction is necessary in order to generate effective counter narratives in information operations. This research advances an additional method to inform practitioners and policy makers of how environmental security and propaganda intersect.

Keywords: propaganda analysis, emotive triggers environmental security, frames

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Authors: Jerzy Banski

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Small towns represent a key element of settlement structure and serve a number of important functions associated with the servicing of rural areas that surround them. It is in light of this that scientific studies have paid considerable attention to the functional structure of centers of this kind, as well as the relationships with both surrounding rural areas and other urban centers. But a preliminary to such research has typically involved attempts at classifying the urban centers themselves, with this also assisting with the planning and shaping of development policy on different spatial scales. The purpose of the work is to test out the methods underpinning three different classifications of small urban centers, as well as to offer a preliminary interpretation of the outcomes obtained. Research took in 722 settlement units in Poland, granted town rights and populated by fewer than 20,000 inhabitants. A morphologically-based classification making reference to the database of topographic objects as regards land cover within the administrative boundaries of towns and cities was carried out, and it proved possible to distinguish the categories of “housing-estate”, industrial and R&R towns, as well as towns characterized by dichotomy. Equally, a functional/morphological approach taken with the same database allowed for the identification – via an alternative method – of three main categories of small towns (i.e., the monofunctional, multifunctional or oligo functional), which could then be described in far greater detail. A third, multi-criterion classification made simultaneous reference to the conditioning of a structural, a location-related, and an administrative hierarchy-related nature, allowing for distinctions to be drawn between small towns in 9 different categories. The results obtained allow for multifaceted analysis and interpretation of the geographical differentiation characterizing the distribution of Poland’s urban centers across space in the country.

Keywords: small towns, classification, local planning, Poland

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Authors: Zbigniew Czyz, Ksenia Siadkowska, Krzysztof Skiba, Karol Scislowski

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Today’s progress in the rotorcraft is mostly associated with an optimization of aircraft performance achieved by active and passive modifications of main rotor assemblies and a tail propeller. The key task is to improve their performance, improve the hover quality factor for rotors but not change in specific fuel consumption. One of the tasks to improve the helicopter is an active optimization of the main rotor providing for flight stages, i.e., an ascend, flight, a descend. An active interference with the airflow around the rotor blade section can significantly change characteristics of the aerodynamic airfoil. The efficiency of actuator systems modifying aerodynamic coefficients in the current solutions is relatively high and significantly affects the increase in strength. The solution to actively change aerodynamic characteristics assumes a periodic change of geometric features of blades depending on flight stages. Changing geometric parameters of blade warping enables an optimization of main rotor performance depending on helicopter flight stages. Structurally, an adaptation of shape memory alloys does not significantly affect rotor blade fatigue strength, which contributes to reduce costs associated with an adaptation of the system to the existing blades, and gains from a better performance can easily amortize such a modification and improve profitability of such a structure. In order to obtain quantitative and qualitative data to solve this research problem, a number of numerical analyses have been necessary. The main problem is a selection of design parameters of the main rotor and a preliminary optimization of its performance to improve the hover quality factor for rotors. This design concept assumes a three-bladed main rotor with a chord of 0.07 m and radius R = 1 m. The value of rotor speed is a calculated parameter of an optimization function. To specify the initial distribution of geometric warping, a special software has been created that uses a numerical method of a blade element which respects dynamic design features such as fluctuations of a blade in its joints. A number of performance analyses as a function of rotor speed, forward speed, and altitude have been performed. The calculations were carried out for the full model assembly. This approach makes it possible to observe the behavior of components and their mutual interaction resulting from the forces. The key element of each rotor is the shaft, hub and pins holding the joints and blade yokes. These components are exposed to the highest loads. As a result of the analysis, the safety factor was determined at the level of k > 1.5, which gives grounds to obtain certification for the strength of the structure. The construction of the joint rotor has numerous moving elements in its structure. Despite the high safety factor, the places with the highest stresses, where the signs of wear and tear may appear, have been indicated. The numerical analysis carried out showed that the most loaded element is the pin connecting the modular bearing of the blade yoke with the element of the horizontal oscillation joint. The stresses in this element result in a safety factor of k=1.7. The other analysed rotor components have a safety factor of more than 2 and in the case of the shaft, this factor is more than 3. However, it must be remembered that the structure is as strong as the weakest cell is. Designed rotor for unmanned aerial vehicles adapted to work with blades with intelligent materials in its structure meets the requirements for certification testing. Acknowledgement: This work has been financed by the Polish National Centre for Research and Development under the LIDER program, Grant Agreement No. LIDER/45/0177/L-9/17/NCBR/2018.

Keywords: main rotor, rotorcraft aerodynamics, shape memory alloy, materials, unmanned helicopter

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Authors: Luis E. Zapata, Sergio Ruiz, María F. Mantilla, Jhon A. Villamizar

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Sand as fine aggregate for concrete production needs a feasible substitute due to several environmental issues. In this work, a study of the behavior of self-compacting concrete mixtures under replacement of sand by iron slag from 0.0% to 50.0% of weight and variations of water/cementitious material ratio between 0.3 and 0.5 is presented. Control fresh state tests of Slump flow, T500, J-ring and L-box were determined. In the hardened state, compressive strength was determined and optimization from response surface analysis was performed. The study of the variables in the hardened state was developed based on inferential statistical analyses using central composite design methodology and posterior analyses of variance (ANOVA). An increase in the compressive strength up to 50% higher than control mixtures at 7, 14, and 28 days of maturity was the most relevant result regarding the presence of iron slag as replacement of natural sand. Considering the obtained result, it is possible to infer that iron slag is an acceptable alternative replacement material of the natural fine aggregate to be used in structural concrete.

Keywords: ANOVA, iron slag, response surface analysis, self-compacting concrete

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Authors: Hong-Min Kim, Da-Som Han, Myong-Hoon Lee

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CLCs (Cholesteric liquid crystals) draw tremendous interest due to their potential in various applications such as cholesteric color filters in LCD devices. CLC possesses helical molecular orientation which is induced by a chiral dopant molecules mixed with nematic liquid crystals. The efficiency of a chiral dopant is quantified by the HTP (helical twisting power). In this work, we designed and synthesized a series of new chiral dopants having a Schiff’s base imine structure with different alkyl chain lengths (butyl, hexyl and octyl) from chiral naphthyl amine by two-step reaction. The structures of new chiral dopants were confirmed by 1H-NMR and IR spectroscopy. The properties were investigated by DSC (differential scanning calorimetry calorimetry), POM (polarized optical microscopy) and UV-Vis spectrophotometer. These solid state chiral dopants showed excellent solubility in nematic LC (MLC-6845-000) higher than 17wt%. We prepared the CLC(Cholesteric Liquid Crystal) cell by mixing nematic LC (MLC-6845-000) with different concentrations of chiral dopants and injecting into the sandwich cell of 5μm cell gap with antiparallel alignment. The cholesteric liquid crystal phase was confirmed from POM, in which all the samples showed planar phase, a typical phase of the cholesteric liquid crystals. The HTP (helical twisting power) is one of the most important properties of CLC. We measured the HTP values from the UV-Vis transmittance spectra of CLC cells with varies chiral dopant concentration. The HTP values with different alkyl chains are as follows: butyl chiral dopant=29.8μm-1; hexyl chiral dopant= 31.8μm-1; octyl chiral dopant=27.7μm-1. We obtained the red, green and blue reflection color from CLC cells, which can be used as color filters in LCDs applications.

Keywords: cholesteric liquid crystal, color filter, display, HTP

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Authors: Seong Woon Lee, Soo Min Lim, Sung Sik Jeong, Jung Hoon Park

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The atmospheric concentration of greenhouse gas (GHG, Green House Gas) is increasing continuously as a result of the combustion of fossil fuels and industrial development. In response to this trend, many researches have been conducted on the reduction of GHG. Landfill gas (LFG, Land Fill Gas) is one of largest sources of GHG emissions containing the methane (CH₄) as a major constituent and can be considered renewable energy sources as well. In order to use LFG by connecting to the city pipe network, it required a process for removing impurities. In particular, oxygen must be removed because it can cause corrosion of pipes and engines. In this study, methane oxidation was used to eliminate oxygen from LFG and perovskite-type ceramic catalysts of La-Sr-Co-Fe-O composition was selected as a catalyst. Hollow fiber catalysts (HFC, Hollow Fiber Catalysts) have attracted attention as a new concept alternative because they have high specific surface area and mechanical strength compared to other types of catalysts. HFC was prepared by a phase-inversion/sintering technique using commercial La-Sr-Co-Fe-O powder. In order to measure the catalysts' activity, simulated LFG was used for feed gas and complete oxidation reaction of methane was confirmed. Pore structure of the HFC was confirmed by SEM image and perovskite structure of single phase was analyzed by XRD. In addition, TPR analysis was performed to verify the oxygen adsorption mechanism of the HFC. Acknowledgement—The project is supported by the ‘Global Top Environment R&D Program’ in the ‘R&D Center for reduction of Non-CO₂ Greenhouse gases’ (Development and demonstration of oxygen removal technology of landfill gas) funded by Korea Ministry of Environment (ME).

Keywords: complete oxidation, greenhouse gas, hollow fiber catalyst, land fill gas, oxygen removal, perovskite catalyst

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Authors: Osman Adiguzel

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Shape memory effect is a peculiar property exhibited by certain alloy systems and based on martensitic transformation, and shape memory properties are closely related to the microstructures of the material. Shape memory effect is linked with martensitic transformation, which is a solid state phase transformation and occurs with the cooperative movement of atoms by means of lattice invariant shears on cooling from high-temperature parent phase. Lattice twinning and detwinning can be considered as elementary processes activated during the transformation. Thermally induced martensite occurs as martensite variants, in self-accommodating manner and consists of lattice twins. Also, this martensite is called the twinned martensite or multivariant martensite. Deformation of shape memory alloys in martensitic state proceeds through a martensite variant reorientation. The martensite variants turn into the reoriented single variants with deformation, and the reorientation process has great importance for the shape memory behavior. Copper based alloys exhibit this property in metastable β- phase region, which has DO3 –type ordered lattice in ternary case at high temperature, and these structures martensiticaly turn into the layered complex structures with lattice twinning mechanism, on cooling from high temperature parent phase region. The twinning occurs as martensite variants with lattice invariant shears in two opposite directions, <110 > -type directions on the {110}- type plane of austenite matrix. Lattice invariant shear is not uniform in copper based ternary alloys and gives rise to the formation of unusual layered structures, like 3R, 9R, or 18R depending on the stacking sequences on the close-packed planes of the ordered lattice. The unit cell and periodicity are completed through 18 atomic layers in case of 18R-structure. On the other hand, the deformed material recovers the original shape on heating above the austenite finish temperature. Meanwhile, the material returns to the twinned martensite structures (thermally induced martensite structure) in one way (irreversible) shape memory effect on cooling below the martensite finish temperature, whereas the material returns to the detwinned martensite structure (deformed martensite) in two-way (reversible) shape memory effect. Shortly one can say that the microstructural mechanisms, responsible for the shape memory effect are the twinning and detwinning processes as well as martensitic transformation. In the present contribution, x-ray diffraction, transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) studies were carried out on two copper-based ternary alloys, CuZnAl, and CuAlMn.

Keywords: shape memory effect, martensitic transformation, twinning and detwinning, layered structures

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Authors: Lijuan Zhou, Mengqi Wu, Changyong Niu

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Attributed graph clustering can utilize the graph topology and node attributes to uncover hidden community structures and patterns in complex networks, aiding in the understanding and analysis of complex systems. Utilizing contrastive learning for attributed graph clustering can effectively exploit meaningful implicit relationships between data. However, existing attributed graph clustering methods based on contrastive learning suffer from the following drawbacks: 1) Complex data augmentation increases computational cost, and inappropriate data augmentation may lead to semantic drift. 2) The selection of positive and negative samples neglects the intrinsic cluster structure learned from graph topology and node attributes. Therefore, this paper proposes a method called self-supervised Attributed Graph Clustering with Dual Contrastive Loss constraints (AGC-DCL). Firstly, Siamese Multilayer Perceptron (MLP) encoders are employed to generate two views separately to avoid complex data augmentation. Secondly, the neighborhood contrastive loss is introduced to constrain node representation using local topological structure while effectively embedding attribute information through attribute reconstruction. Additionally, clustering-oriented contrastive loss is applied to fully utilize clustering information in global semantics for discriminative node representations, regarding the cluster centers from two views as negative samples to fully leverage effective clustering information from different views. Comparative clustering results with existing attributed graph clustering algorithms on six datasets demonstrate the superiority of the proposed method.

Keywords: attributed graph clustering, contrastive learning, clustering-oriented, self-supervised learning

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Authors: C. E. Ihejirika, M. I. Nwachukwu, R. F. Njoku-Tony, O. C. Ihejirika, U. O. Enwereuzoh, E. O. Imo, D. C. Ashiegbu

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Disposal of industrial solid wastes in the environment is a major environmental challenge. This study investigated the effects of calcium carbide waste dumpsites on soil quality. Soil samples were collected with hand auger from three different dumpsites at varying depths and made into composite samples. Samples were subjected to standard analytical procedures. pH varied from 10.38 to 8.28, nitrate from 5.6mg/kg to 9.3mg/kg, phosphate from 8.8mg/kg to 12.3mg/kg, calcium carbide reduced from 10% to to 3%. Calcium carbide was absent in control soil samples. Bacterial counts from dumpsites ranged from 1.8 x 105cfu/g - 2.5 x 105cfu/g while fungal ranged from 0.8 x 103cfu/g - 1.4 x 103cfu/g. Bacterial isolates included Pseudomonas spp, Flavobacterium spp, and Achromobacter spp, while fungal isolates include Penicillium notatum, Aspergillus niger, and Rhizopus stolonifer. No organism was isolated from the dumpsites at soil depth of 0-15 cm, while there were isolates from other soil depths. Toxicity might be due to alkaline condition of the dumpsite. Calcium carbide might be bactericidal and fungicidal leading to cellular physiology, growth retardation, death, general loss of biodiversity and reduction of ecosystem processes. Detoxification of calcium carbide waste before disposal on soil might be the best option in management.

Keywords: biodiversity, calcium-carbide, denitrification, toxicity

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Authors: Yuriy A. Knirel

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Enteric bacteria Escherichia coli is the predominant facultative anaerobe of the colonic flora, and some specific serotypes are associated with enteritis, hemorrhagic colitis, and hemolytic uremic syndrome. Shigella spp. are human pathogens that cause diarrhea and bacillary dysentery (shigellosis). They are in effect E. coli with a specific mode of pathogenicity. Strains of Salmonella enterica are responsible for a food-borne infection (salmonellosis), and specific serotypes cause typhoid fever and paratyphoid fever. All these bacteria are closely related in respect to structure and genetics of the lipopolysaccharide, including the O-polysaccharide part (O‑antigen). Being exposed to the bacterial cell surface, the O antigen is subject to intense selection by the host immune system and bacteriophages giving rise to diverse O‑antigen forms and providing the basis for typing of bacteria. The O-antigen forms of many bacteria are unique, but some are structurally and genetically related to others. The sequenced O-antigen gene clusters between conserved galF and gnd genes were analyzed taking into account the O-antigen structures established by us and others for all S. enterica and Shigella and most E. coli O-serogroups. Multiple genetic mechanisms of diversification of the O-antigen forms, such as lateral gene transfer and mutations, were elucidated and are summarized in the present paper. They include acquisition or inactivation of genes for sugar synthesis or transfer or recombination of O-antigen gene clusters or their parts. The data obtained contribute to our understanding of the origins of the O‑antigen diversity, shed light on molecular evolutionary relationships between the O-antigens of enteric bacteria, and open a way for studies of the role of gene polymorphism in pathogenicity.

Keywords: enteric bacteria, O-antigen gene cluster, polysaccharide biosynthesis, polysaccharide structure

Procedia PDF Downloads 144

Authors: Tahani Aljohani, Jialin Yu, Alexandra. I. Cristea

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The more an educational system knows about a learner, the more personalised interaction it can provide, which leads to better learning. However, asking a learner directly is potentially disruptive, and often ignored by learners. Especially in the booming realm of MOOC Massive Online Learning platforms, only a very low percentage of users disclose demographic information about themselves. Thus, in this paper, we aim to predict learners’ demographic characteristics, by proposing an approach using linguistically motivated Deep Learning Architectures for Learner Profiling, particularly targeting gender prediction on a FutureLearn MOOC platform. Additionally, we tackle here the difficult problem of predicting the gender of learners based on their comments only – which are often available across MOOCs. The most common current approaches to text classification use the Long Short-Term Memory (LSTM) model, considering sentences as sequences. However, human language also has structures. In this research, rather than considering sentences as plain sequences, we hypothesise that higher semantic - and syntactic level sentence processing based on linguistics will render a richer representation. We thus evaluate, the traditional LSTM versus other bleeding edge models, which take into account syntactic structure, such as tree-structured LSTM, Stack-augmented Parser-Interpreter Neural Network (SPINN) and the Structure-Aware Tag Augmented model (SATA). Additionally, we explore using different word-level encoding functions. We have implemented these methods on Our MOOC dataset, which is the most performant one comparing with a public dataset on sentiment analysis that is further used as a cross-examining for the models' results.

Keywords: deep learning, data mining, gender predication, MOOCs

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Authors: Surabhi Pandey, Pavuluri Srinivasa Rao

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Extrusion processing is a high-temperature short time (HTST) treatment which can improve protein quality and digestibility together with retaining active nutrients. In-vitro protein digestibility of plant protein-based foods is generally enhanced by extrusion. The current study aimed to investigate the effect of extrusion cooking on in-vitro protein digestibility (IVPD) and conformational modification of protein in green banana flour extrudates. Green banana flour was extruded through a co-rotating twin-screw extruder varying the moisture content, barrel temperature, screw speed in the range of 10-20 %, 60-80 °C, 200-300 rpm, respectively, at constant feed rate. Response surface methodology was used to optimise the result for IVPD. Fourier-transform infrared spectroscopy (FTIR) analysis provided a convenient and powerful means to monitor interactions and changes in functional and conformational properties of extrudates. Results showed that protein digestibility was highest in extrudate produced at 80°C, 250 rpm and 15% feed moisture. FTIR analysis was done for the optimised sample having highest IVPD. FTIR analysis showed that there were no changes in primary structure of protein while the secondary protein structure changed. In order to explain this behaviour, infrared spectroscopy analysis was carried out, mainly in the amide I and II regions. Moreover, curve fitting analysis showed the conformational changes produced in the flour due to protein denaturation. The quantitative analysis of the changes in the amide I and II regions provided information about the modifications produced in banana flour extrudates.

Keywords: extrusion, FTIR, protein conformation, raw banana flour, SDS-PAGE method

Procedia PDF Downloads 163

Authors: B. Nečasová, P. Liška, J. Šlanhof

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Verification of vented wooden façade system with bonded joints is presented in this paper. The potential of bonded joints is studied and described in more detail. The paper presents the results of an experimental and theoretical research about the effects of freeze cycling on the bonded joint. For the purpose of tests spruce timber profiles were chosen for the load bearing substructure. Planks from wooden plastic composite and Siberian larch are representing facade cladding. Two types of industrial polyurethane adhesives intended for structural bonding were selected. The article is focused on the preparation as well as on the subsequent curing and conditioning of test samples. All test samples were subjected to 15 cycles that represents sudden temperature changes, i.e. immersion in a water bath at (293.15 ± 3) K for 6 hours and subsequent freezing to (253.15 ± 2) K for 18 hours. Furthermore, the retention of bond strength between substructure and cladding was tested and strength in shear was determined under tensile stress. Research data indicate that little, if any, damage to the bond results from freezing cycles. Additionally, the suitability of selected group of adhesives in combination with timber substructure was confirmed.

Keywords: adhesive system, bonded joints, wooden lightweight façade, timber substructure

Procedia PDF Downloads 395