Search results for: left ventricular parameters
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 9833

Search results for: left ventricular parameters

6443 Risk Assessment on Construction Management with “Fuzzy Logy“

Authors: Mehrdad Abkenari, Orod Zarrinkafsh, Mohsen Ramezan Shirazi

Abstract:

Construction projects initiate in complicated dynamic environments and, due to the close relationships between project parameters and the unknown outer environment, they are faced with several uncertainties and risks. Success in time, cost and quality in large scale construction projects is uncertain in consequence of technological constraints, large number of stakeholders, too much time required, great capital requirements and poor definition of the extent and scope of the project. Projects that are faced with such environments and uncertainties can be well managed through utilization of the concept of risk management in project’s life cycle. Although the concept of risk is dependent on the opinion and idea of management, it suggests the risks of not achieving the project objectives as well. Furthermore, project’s risk analysis discusses the risks of development of inappropriate reactions. Since evaluation and prioritization of construction projects has been a difficult task, the network structure is considered to be an appropriate approach to analyze complex systems; therefore, we have used this structure for analyzing and modeling the issue. On the other hand, we face inadequacy of data in deterministic circumstances, and additionally the expert’s opinions are usually mathematically vague and are introduced in the form of linguistic variables instead of numerical expression. Owing to the fact that fuzzy logic is used for expressing the vagueness and uncertainty, formulation of expert’s opinion in the form of fuzzy numbers can be an appropriate approach. In other words, the evaluation and prioritization of construction projects on the basis of risk factors in real world is a complicated issue with lots of ambiguous qualitative characteristics. In this study, evaluated and prioritization the risk parameters and factors with fuzzy logy method by combination of three method DEMATEL (Decision Making Trial and Evaluation), ANP (Analytic Network Process) and TOPSIS (Technique for Order-Preference by Similarity Ideal Solution) on Construction Management.

Keywords: fuzzy logy, risk, prioritization, assessment

Procedia PDF Downloads 586
6442 Optimizing the Design Parameters of Acoustic Power Transfer Model to Achieve High Power Intensity and Compact System

Authors: Ariba Siddiqui, Amber Khan

Abstract:

The need for bio-implantable devices in the field of medical sciences has been increasing day by day; however, the charging of these devices is a major issue. Batteries, a very common method of powering the implants, have a limited lifetime and bulky nature. Therefore, as a replacement of batteries, acoustic power transfer (APT) technology is being accepted as the most suitable technique to wirelessly power the medical implants in the present scenario. The basic model of APT consists of piezoelectric transducers that work on the principle of converse piezoelectric effect at the transmitting end and direct piezoelectric effect at the receiving end. This paper provides mechanistic insight into the parameters affecting the design and efficient working of acoustic power transfer systems. The optimum design considerations have been presented that will help to compress the size of the device and augment the intensity of the pressure wave. A COMSOL model of the PZT (Lead Zirconate Titanate) transducer was developed. The model was simulated and analyzed on a frequency spectrum. The simulation results displayed that the efficiency of these devices is strongly dependent on the frequency of operation, and a wrong choice of the operating frequency leads to the high absorption of acoustic field inside the tissue (medium), poor power strength, and heavy transducers, which in effect influence the overall configuration of the acoustic systems. Considering all the tradeoffs, the simulations were performed again by determining an optimum frequency (900 kHz) that resulted in the reduction of the transducer's thickness to 1.96 mm and augmented the power strength with an intensity of 432 W/m². Thus, the results obtained after the second simulation contribute to lesser attenuation, lightweight systems, high power intensity, and also comply with safety limits provided by the U.S Food and Drug Administration (FDA). It was also found that the chosen operating frequency enhances the directivity of the acoustic wave at the receiver side.

Keywords: acoustic power, bio-implantable, COMSOL, Lead Zirconate Titanate, piezoelectric, transducer

Procedia PDF Downloads 169
6441 Degradation of Emerging Pharmaceuticals by Gamma Irradiation Process

Authors: W. Jahouach-Rabai, J. Aribi, Z. Azzouz-Berriche, R. Lahsni, F. Hosni

Abstract:

Gamma irradiation applied in removing pharmaceutical contaminants from wastewater is an effective advanced oxidation process (AOP), considered as an alternative to conventional water treatment technologies. In this purpose, the degradation efficiency of several detected contaminants under gamma irradiation was evaluated. In fact, radiolysis of organic pollutants in aqueous solutions produces powerful reactive species, essentially hydroxyl radical ( ·OH), able to destroy recalcitrant pollutants in water. Pharmaceuticals considered in this study are aqueous solutions of paracetamol, ibuprofen, and diclofenac at different concentrations 0.1-1 mmol/L, which were treated with irradiation doses from 3 to 15 kGy. The catalytic oxidation of these compounds by gamma irradiation was investigated using hydrogen peroxide (H₂O₂) as a convenient oxidant. Optimization of the main parameters influencing irradiation process, namely irradiation doses, initial concentration and oxidant volume (H₂O₂) were investigated, in the aim to release high degradation efficiency of considered pharmaceuticals. Significant modifications attributed to these parameters appeared in the variation of degradation efficiency, chemical oxygen demand removal (COD) and concentration of radio-induced radicals, confirming them synergistic effect to attempt total mineralization. Pseudo-first-order reaction kinetics could be used to depict the degradation process of these compounds. A sophisticated analytical study was released to quantify the detected radio-induced radicals (electron paramagnetic resonance spectroscopy (EPR) and high performance liquid chromatography (HPLC)). All results showed that this process is effective for the degradation of many pharmaceutical products in aqueous solutions due to strong oxidative properties of generated radicals mainly hydroxyl radical. Furthermore, the addition of an optimal amount of H₂O₂ was efficient to improve the oxidative degradation and contribute to the high performance of this process at very low doses (0.5 and 1 kGy).

Keywords: AOP, COD, hydroxyl radical, EPR, gamma irradiation, HPLC, pharmaceuticals

Procedia PDF Downloads 167
6440 Importance of the Bali Strait for Devil Ray Reproduction

Authors: Irianes C. Gozali, Betty J.L. Laglbauer, Muhammad G. Salim, Sila K. Sari, Fahmi Fahmi, Selvia Oktaviyani

Abstract:

Muncar, located off the eastern coast of Java, is an important fishing port for small-scale fleets which land mobulid rays as retained bycatch, primarily in drift gillnets. Due to overlap with fishing grounds in the Bali Strait, three devil ray species are landed in Muncar, the spinetail devil ray Mobula mobular, the bentfin devil ray Mobula thurstoni, and the Chilean devil ray Mobula tarapacana, which are all listed as Endangered by the International Union for the Conservation of Nature. However, despite the importance of life-history data to better manage stocks, such information is still rare or unavailable for Indonesian mobulid ray populations. Using morphometric data, reproductive assessments, and samples collected from dead specimens at fish markets from 2015-2019, we provide information on the maturity stage, reproductive periodicity, gestation, and size at parturition. A majority of immature individuals of all three devil ray species were recorded (<10% individuals in Mobula mobular to <30% individuals in Mobula thurstoni). Pregnant females of two species, Mobula mobular and Mobula thurstoni were recorded containing embryos of various developmental stages (each with a single embryo in the left functional uterus), while for Mobula tarapacana, no fetuses were found. The largest embryo recorded in M. mobular was within the range of that previously reported for neonates of the species in Indonesia (957 cm, for a 920-994 range), and represents a near-term embryo reflecting size at parturition. Low reproductive output was confirmed for the study-species. Based on this study, we infer that the Bali Straight is likely an important location for devil ray reproduction, which raises concern for the sustainability of mobulid ray populations in the face of bycatch in drift gillnets. Potential management approaches to tackle this issue are discussed.

Keywords: devil ray, mobulid, reproduction, Indonesia

Procedia PDF Downloads 176
6439 Validation Study of Radial Aircraft Engine Model

Authors: Lukasz Grabowski, Tytus Tulwin, Michal Geca, P. Karpinski

Abstract:

This paper presents the radial aircraft engine model which has been created in AVL Boost software. This model is a one-dimensional physical model of the engine, which enables us to investigate the impact of an ignition system design on engine performance (power, torque, fuel consumption). In addition, this model allows research under variable environmental conditions to reflect varied flight conditions (altitude, humidity, cruising speed). Before the simulation research the identifying parameters and validating of model were studied. In order to verify the feasibility to take off power of gasoline radial aircraft engine model, some validation study was carried out. The first stage of the identification was completed with reference to the technical documentation provided by manufacturer of engine and the experiments on the test stand of the real engine. The second stage involved a comparison of simulation results with the results of the engine stand tests performed on a WSK ’PZL-Kalisz’. The engine was loaded by a propeller in a special test bench. Identifying the model parameters referred to a comparison of the test results to the simulation in terms of: pressure behind the throttles, pressure in the inlet pipe, and time course for pressure in the first inlet pipe, power, and specific fuel consumption. Accordingly, the required coefficients and error of simulation calculation relative to the real-object experiments were determined. Obtained the time course for pressure and its value is compatible with the experimental results. Additionally the engine power and specific fuel consumption tends to be significantly compatible with the bench tests. The mapping error does not exceed 1.5%, which verifies positively the model of combustion and allows us to predict engine performance if the process of combustion will be modified. The next conducted tests verified completely model. The maximum mapping error for the pressure behind the throttles and the inlet pipe pressure is 4 %, which proves the model of the inlet duct in the engine with the charging compressor to be correct.

Keywords: 1D-model, aircraft engine, performance, validation

Procedia PDF Downloads 331
6438 Compact 3-D Co-Planar Waveguide Fed Dual-Port Ultrawideband-Multiple-Input and Multiple-Output Antenna with WLAN Band-Notched Characteristics

Authors: Asim Quddus

Abstract:

A miniaturized three dimensional co-planar waveguide (CPW) two-port MIMO antenna, exhibiting high isolation and WLAN band-notched characteristics is presented in this paper for ultrawideband (UWB) communication applications. The microstrip patch antenna operates as a single UWB antenna element. The proposed design is a cuboid-shaped structure having compact size of 35 x 27 x 45 mm³. Radiating as well as decoupling structure is placed around cuboidal polystyrene sheet. The radiators are 27 mm apart, placed Face-to-Face in vertical direction. Decoupling structure is placed on the side walls of polystyrene. The proposed antenna consists of an oval shaped radiating patch. A rectangular structure with fillet edges is placed on ground plan to enhance the bandwidth. The proposed antenna exhibits a good impedance match (S11 ≤ -10 dB) over frequency band of 2 GHz – 10.6 GHz. A circular slotted structure is employed as a decoupling structure on substrate, and it is placed on the side walls of polystyrene to enhance the isolation between antenna elements. Moreover, to achieve immunity from WLAN band distortion, a modified, inverted crescent shaped slotted structure is etched on radiating patches to achieve band-rejection characteristics at WLAN frequency band 4.8 GHz – 5.2 GHz. The suggested decoupling structure provides isolation better than 15 dB over the desired UWB spectrum. The envelope correlation coefficient (ECC) and gain for the MIMO antenna are analyzed as well. Finite Element Method (FEM) simulations are carried out in Ansys High Frequency Structural Simulator (HFSS) for the proposed design. The antenna is realized on a Rogers RT/duroid 5880 with thickness 1 mm, relative permittivity ɛr = 2.2. The proposed antenna achieves a stable omni-directional radiation patterns as well, while providing rejection at desired WLAN band. The S-parameters as well as MIMO parameters like ECC are analyzed and the results show conclusively that the design is suitable for portable MIMO-UWB applications.

Keywords: 3-D antenna, band-notch, MIMO, UWB

Procedia PDF Downloads 294
6437 Optimization of Shale Gas Production by Advanced Hydraulic Fracturing

Authors: Fazl Ullah, Rahmat Ullah

Abstract:

This paper shows a comprehensive learning focused on the optimization of gas production in shale gas reservoirs through hydraulic fracturing. Shale gas has emerged as an important unconventional vigor resource, necessitating innovative techniques to enhance its extraction. The key objective of this study is to examine the influence of fracture parameters on reservoir productivity and formulate strategies for production optimization. A sophisticated model integrating gas flow dynamics and real stress considerations is developed for hydraulic fracturing in multi-stage shale gas reservoirs. This model encompasses distinct zones: a single-porosity medium region, a dual-porosity average region, and a hydraulic fracture region. The apparent permeability of the matrix and fracture system is modeled using principles like effective stress mechanics, porous elastic medium theory, fractal dimension evolution, and fluid transport apparatuses. The developed model is then validated using field data from the Barnett and Marcellus formations, enhancing its reliability and accuracy. By solving the partial differential equation by means of COMSOL software, the research yields valuable insights into optimal fracture parameters. The findings reveal the influence of fracture length, diversion capacity, and width on gas production. For reservoirs with higher permeability, extending hydraulic fracture lengths proves beneficial, while complex fracture geometries offer potential for low-permeability reservoirs. Overall, this study contributes to a deeper understanding of hydraulic cracking dynamics in shale gas reservoirs and provides essential guidance for optimizing gas production. The research findings are instrumental for energy industry professionals, researchers, and policymakers alike, shaping the future of sustainable energy extraction from unconventional resources.

Keywords: fluid-solid coupling, apparent permeability, shale gas reservoir, fracture property, numerical simulation

Procedia PDF Downloads 63
6436 The Abnormality of Blood Cells Parasitized by Plasmodium vivax

Authors: Manas Kotepui, Kwuntida Uthaisar, Phiman Thirarattanasunthon, Bhukdee PhunPhuech, Nuoil Phiwklam

Abstract:

Introduction: Malaria due to Plasmodium vivax has placed huge burdens on the health, longevity, and general prosperity of large sections of the human population. This study aimed at prospectively collecting information on the clinical profile of Plasmodium vivax from subjects acutely infected with P. vivax residing in some of the highest malaria transmission regions in Thailand. Methods: A retrospective study of malaria cases, hospitalized between 2013 and 2015 was performed. Clinical characteristics, diagnosis, and parasitological results on admission, age, and gender were mined from medical records at Phop Phra Hospital located in endemic areas of Tak Province, Thailand. Venous blood samples were collected at the time of admission to the hospital to determine the present of parasite and also parasite count by thick and thin film examination, and also Complete blood count (CBC) parameters. Results: Results showed that patients infected with Plasmodium vivax (276 cases) had a high monocyte count (mean=390 cells/µL) during initial stage of infection and continuously lower during later stage (any stage with gametocyte, mean=230 cells/µL) of infection (P value=0.021) whereas, patients infected with Plasmodium vivax had a low basophil count (mean=20 cells/µL) during initial stage of infection and continuously higher during later stage of infection (mean at stage with gametocyte=70 cells/µL) (P value=0.033). In addition, patients with more than one stage infection tend to have lower lymphocyte count (mean=1180 cells/µL) than patients with only one stage infection (mean=1350 cells/µL)(P value=0.011) whereas, patients with more than one stage infection tend to have lower basophil count (mean=60 cells/µL) than patients with only one stage infection (mean=80 cells/µL) (P value=0.01). Conclusion: This study indicated that patients infected with Plasmodium vivax had high monocyte count and low basophil count during initial stage of infection which was continuously lower during later stage of infection. Patients with more than one stage infection tend to have lower lymphocyte count than patients with only one stage infection whereas, patients with more than one stage infection tend to have lower basophil count than patients with only one stage infection. This information contributes to better understanding of pathological characteristic of Plasmodium vivax infection.

Keywords: plasmodium vivax, Thailand, asexual erythrocytic stages, hematological parameters

Procedia PDF Downloads 203
6435 Investigation of Interlayer Shear Effects in Asphalt Overlay on Existing Rigid Airfield Pavement Using Digital Image Correlation

Authors: Yuechao Lei, Lei Zhang

Abstract:

The interface shear between asphalt overlay and existing rigid airport pavements occurs due to differences in the mechanical properties of materials subjected to aircraft loading. Interlayer contact influences the mechanical characteristics of the asphalt overlay directly. However, the effective interlayer relative displacement obtained accurately using existing displacement sensors of the loading apparatus remains challenging. This study aims to utilize digital image correlation technology to enhance the accuracy of interfacial contact parameters by obtaining effective interlayer relative displacements. Composite structure specimens were prepared, and fixtures for interlayer shear tests were designed and fabricated. Subsequently, a digital image recognition scheme for required markers was designed and optimized. Effective interlayer relative displacement values were obtained through image recognition and calculation of surface markers on specimens. Finite element simulations validated the mechanical response of composite specimens with interlayer shearing. Results indicated that an optimized marking approach using the wall mending agent for surface application and color coding enhanced the image recognition quality of marking points on the specimen surface. Further image extraction provided effective interlayer relative displacement values during interlayer shear, thereby improving the accuracy of interface contact parameters. For composite structure specimens utilizing Styrene-Butadiene-Styrene (SBS) modified asphalt as the tack coat, the corresponding maximum interlayer shear stress strength was 0.6 MPa, and fracture energy was 2917 J/m2. This research provides valuable insights for investigating the impact of interlayer contact in composite pavement structures on the mechanical characteristics of asphalt overlay.

Keywords: interlayer contact, effective relative displacement, digital image correlation technology, composite pavement structure, asphalt overlay

Procedia PDF Downloads 45
6434 International Peace and Security: a Study in the Light of the Provisions of the Charter of the United Nations

Authors: Djehich Mohamed Yousri

Abstract:

As a result of the destruction and devastation left by the two world wars, the international community worked to establish a global organization based on a contractual basis, in which the Security Council was entrusted with the task of working to maintain international peace and security, and to achieve this, the United Nations Charter assigned the latter a wide authority to adapt everything It would threaten international peace and security, although the examiner of the Charter of the United Nations does not find the slightest definition of the concept of international peace and security, although these two principles are among the basic principles that the Charter stipulated the necessity of achieving, and perhaps this was also what was in the opposite case for them. And by that, we mean cases of a threat to peace, a breach of it, or an act of aggression. These terms were not dealt with in the Charter in explanation and detail, leaving ample room for the Security Council to assess each of these cases separately, and perhaps this is due to the fact that the framers of the Charter intended to set a flexible standard. It does not restrict the authority of the Security Council to carry out the adjustment process on the one hand and, on the other hand, to allow and enable the Security Council to keep pace with new developments and threats to which international peace and security are exposed. There is no doubt that the concept of international peace and security has undergone significant changes during the 70-year period that followed the establishment of the international organization. After the threat to peace and security focused - in the first stage - on cases of war or the threat of war, what distinguishes the post- The new world order is the emergence of other challenges and threats that find their source in economic, social, humanitarian, and environmental instability. Perhaps this is what the member states of the Security Council indicated during the preparation of the Peace Agenda. The expansion of the concept of peace and security is what paved the way for some permanent states to use the Security Council to legitimize and implement their decisions and take the council as a tool to implement their foreign policy and punish states instead of maintaining international peace and security, which prompted some states and jurisprudence to call for the establishment of oversight of the decisions of the Council Security on the one hand, and amending the UN Charter to make it more expressive of the aspirations of the international community, referring to the obstacles that prevent this amendment.

Keywords: peace, security, united nations charter, security council, united nations organization

Procedia PDF Downloads 69
6433 Growth of Droplet in Radiation-Induced Plasma of Own Vapour

Authors: P. Selyshchev

Abstract:

The theoretical approach is developed to describe the change of drops in the atmosphere of own steam and buffer gas under irradiation. It is shown that the irradiation influences on size of stable droplet and on the conditions under which the droplet exists. Under irradiation the change of drop becomes more complex: the not monotone and periodical change of size of drop becomes possible. All possible solutions are represented by means of phase portrait. It is found all qualitatively different phase portraits as function of critical parameters: rate generation of clusters and substance density.

Keywords: irradiation, steam, plasma, cluster formation, liquid droplets, evolution

Procedia PDF Downloads 432
6432 The Relationship of Lean Management Principles with Lean Maturity Levels: Multiple Case Study in Manufacturing Companies

Authors: Alexandre D. Ferraz, Dario H. Alliprandini, Mauro Sampaio

Abstract:

Companies and other institutions are constantly seeking better organizational performance and greater competitiveness. In order to fulfill this purpose, there are many tools, methodologies and models for increasing performance. However, the Lean Management approach seems to be the most effective in terms of achieving a significant improvement in productivity relatively quickly. Although Lean tools are relatively easy to understand and implement in different contexts, many organizations are not able to transform themselves into 'Lean companies'. Most of the efforts in its implementation have shown single benefits, failing to achieve the desired impact on the performance of the overall enterprise system. There is also a growing perception of the importance of management in Lean transformation, but few studies have empirically investigated and described the 'Lean Management'. In order to understand more clearly the ideas that guide Lean Management and its influence on the maturity level of the production system, the objective of this research is analyze the relationship between the Lean Management principles and the Lean maturity level in the organizations. The research also analyzes the principles of Lean Management and its relationship with the 'Lean culture' and the results obtained. The research was developed using the case study methodology. Three manufacturing units of a German multinational company from industrial automation segment, located in different countries were studied, in order to have a better comparison between the practices and the level of maturity in the implementation. The primary source of information was the application of a research questionnaire based on the theoretical review. The research showed that higher the level of Lean Management principles, higher are the Lean maturity level, the Lean culture level, and the level of Lean results obtained in the organization. The research also showed that factors such as time for application of Lean concepts and company size were not determinant for the level of Lean Management principles and, consequently, for the level of Lean maturity in the organization. The characteristics of the production system showed much more influence in different evaluated aspects. The present research also left recommendations for the managers of the plants analyzed and suggestions for future research.

Keywords: lean management, lean principles, lean maturity level, lean manufacturing

Procedia PDF Downloads 139
6431 Comparison Between the Radiation Resistance of n/p and p/n InP Solar Cell

Authors: Mazouz Halima, Belghachi Abdrahmane

Abstract:

Effects of electron irradiation-induced deep level defects have been studied on both n/p and p/n indium phosphide solar cells with very thin emitters. The simulation results show that n/p structure offers a somewhat better short circuit current but the p/n structure offers improved circuit voltage, not only before electron irradiation, but also after 1MeV electron irradiation with 5.1015 fluence. The simulation also shows that n/p solar cell structure is more resistant than that of p/n structure.

Keywords: InP solar cell, p/n and n/p structure, electron irradiation, output parameters

Procedia PDF Downloads 543
6430 Towards the Prediction of Aesthetic Requirements for Women’s Apparel Product

Authors: Yu Zhao, Min Zhang, Yuanqian Wang, Qiuyu Yu

Abstract:

The prediction of aesthetics of apparel is helpful for the development of a new type of apparel. This study is to build the quantitative relationship between the aesthetics and its design parameters. In particular, women’s pants have been preliminarily studied. This aforementioned relationship has been carried out by statistical analysis. The contributions of this study include the development of a more personalized apparel design mechanism and the provision of some empirical knowledge for the development of other products in the aspect of aesthetics.

Keywords: aesthetics, crease line, cropped straight leg pants, knee width

Procedia PDF Downloads 183
6429 Tracking the Effect of Ibutilide on Amplitude and Frequency of Fibrillatory Intracardiac Electrograms Using the Regression Analysis

Authors: H. Hajimolahoseini, J. Hashemi, D. Redfearn

Abstract:

Background: Catheter ablation is an effective therapy for symptomatic atrial fibrillation (AF). The intracardiac electrocardiogram (IEGM) collected during this procedure contains precious information that has not been explored to its full capacity. Novel processing techniques allow looking at these recordings from different perspectives which can lead to improved therapeutic approaches. In our previous study, we showed that variation in amplitude measured through Shannon Entropy could be used as an AF recurrence risk stratification factor in patients who received Ibutilide before the electrograms were recorded. The aim of this study is to further investigate the effect of Ibutilide on characteristics of the recorded signals from the left atrium (LA) of a patient with persistent AF before and after administration of the drug. Methods: The IEGMs collected from different intra-atrial sites of 12 patients were studied and compared before and after Ibutilide administration. First, the before and after Ibutilide IEGMs that were recorded within a Euclidian distance of 3 mm in LA were selected as pairs for comparison. For every selected pair of IEGMs, the Probability Distribution Function (PDF) of the amplitude in time domain and magnitude in frequency domain was estimated using the regression analysis. The PDF represents the relative likelihood of a variable falling within a specific range of values. Results: Our observations showed that in time domain, the PDF of amplitudes was fitted to a Gaussian distribution while in frequency domain, it was fitted to a Rayleigh distribution. Our observations also revealed that after Ibutilide administration, the IEGMs would have significantly narrower short-tailed PDFs both in time and frequency domains. Conclusion: This study shows that the PDFs of the IEGMs before and after administration of Ibutilide represents significantly different properties, both in time and frequency domains. Hence, by fitting the PDF of IEGMs in time domain to a Gaussian distribution or in frequency domain to a Rayleigh distribution, the effect of Ibutilide can easily be tracked using the statistics of their PDF (e.g., standard deviation) while this is difficult through the waveform of IEGMs itself.

Keywords: atrial fibrillation, catheter ablation, probability distribution function, time-frequency characteristics

Procedia PDF Downloads 156
6428 Impact of Organic Fertilizer, Inorganic Fertilizer and Soil Conditioner on Growth and Yield of Cowpea (Vigna unguiculata L. Walp) in Sudan Savannah, Nigeria

Authors: Mohammed Bello Sokoto, Adewumi Babatunde Adebayo, Ajit Singh

Abstract:

The field experiment was conducted at the dry land Teaching and Research Farm of Usmanu Danfodiyo University, Sokoto, during the 2023 rainy season to determine the effects of organic, inorganic, soil conditioner and integrated use of soil conditioners (Agzyme) with organic (super gro) and inorganic fertilizers on the growth and yield of cowpea varieties. The research consisted of two cowpea varieties (SAMPEA-20-T and ex-GidanYunfa) and six combinations of organic and inorganic fertilizers and soil conditioners factorially combined and laid out in a Randomized Complete Block Design (RCBD) replicated three times. Data were collected on plant height, leaf area index, number of pods per plant, number of seeds per pod, days to 50% flowering, grain yield, and 100 seed weight. Results indicated that the 100% inorganic fertilizer had a significantly increased growth parameter such as plant height and number of leaves, while combined application of the organic fertilizer and soil conditioner resulted in a significant increase in yield parameters such as number of pods per plant, number of seeds per pod, 100 seed weight and grain yield. The study observed that the use of soil conditioner in combination with fertilizers supports sustainable cowpea production. Application of 50% recommended inorganic + 50% soil conditioner or 50% liquid organic + 50% soil conditioner was better in increasing the number of pods/plant, seeds/pod, 100 seed weight and grain yield. The ex-Gidan Yunfa cowpea variety generally performed better in most parameters measured, such as plant height, days to 50% flowering, number of pods per plant, number of seeds per pod, 100 seed weight and grain yield. Therefore, the combined application of 50% recommended inorganic + 50% soil conditioner or 50% liquid organic + 50% soil conditioner is effective for the sustainable production of cowpeas.

Keywords: integrated, fertilizers, growth, yield, cowpea, Sudan Savannah

Procedia PDF Downloads 33
6427 Alternative Housing Systems: Influence on Blood Profile of Egg-Type Chickens in Humid Tropics

Authors: Olufemi M. Alabi, Foluke A. Aderemi, Adebayo A. Adewumi, Banwo O. Alabi

Abstract:

General well-being of animals is of paramount interest in some developed countries and of global importance hence the shift onto alternative housing systems for egg-type chickens as replacement for conventional battery cage system. However, there is paucity of information on the effect of this shift on physiological status of the hens to judge their health via the blood profile. Therefore, investigation was carried out on two strains of hen kept in three different housing systems in humid tropics to evaluate changes in their blood parameters. 108, 17-weeks old super black (SBL) hens and 108, 17-weeks old super brown (SBR) hens were randomly allotted to three different intensive systems Partitioned Conventional Cage (PCC), Extended Conventional Cage (ECC) and Deep Litter System (DLS) in a randomized complete block design with 36 hens per housing system, each with three replicates. The experiment lasted 37 weeks during which blood samples were collected at 18th week of age and bi-weekly thereafter for analyses. Parameters measured are packed cell volume (PCV), hemoglobin concentration (Hb), red blood counts (RBC), white blood counts (WBC) and serum metabolites such as total protein (TP), albumin (Alb), globulin (Glb), glucose, cholesterol, urea, bilirubin, serum cortisol while blood indices such as mean corpuscular hemoglobin (MCH), mean cell volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) were calculated. The hematological values of the hens were not significantly (p>0.05) affected by the housing system and strain, so also the serum metabolites except for the serum cortisol which was significantly (p<0.05) affected by the housing system only. Hens housed on PCC had higher values (20.05 ng/ml for SBL and 20.55 ng/ml for SBR) followed by hens on ECC (18.15ng/ml for SBL and 18.38ng/ml for SBL) while hens on DLS had the lowest value (16.50ng/ml for SBL and 16.00ng/ml for SBR) thereby confirming indication of stress with conventionally caged birds. Alternative housing systems can also be adopted for egg-type chickens in the humid tropics from welfare point of view with the results of this work confirming stress among caged hens.

Keywords: blood, housing, humid-tropics, layers

Procedia PDF Downloads 459
6426 A Microsurgery-Specific End-Effector Equipped with a Bipolar Surgical Tool and Haptic Feedback

Authors: Hamidreza Hoshyarmanesh, Sanju Lama, Garnette R. Sutherland

Abstract:

In tele-operative robotic surgery, an ideal haptic device should be equipped with an intuitive and smooth end-effector to cover the surgeon’s hand/wrist degrees of freedom (DOF) and translate the hand joint motions to the end-effector of the remote manipulator with low effort and high level of comfort. This research introduces the design and development of a microsurgery-specific end-effector, a gimbal mechanism possessing 4 passive and 1 active DOFs, equipped with a bipolar forceps and haptic feedback. The robust gimbal structure is comprised of three light-weight links/joint, pitch, yaw, and roll, each consisting of low-friction support and a 2-channel accurate optical position sensor. The third link, which provides the tool roll, was specifically designed to grip the tool prongs and accommodate a low mass geared actuator together with a miniaturized capstan-rope mechanism. The actuator is able to generate delicate torques, using a threaded cylindrical capstan, to emulate the sense of pinch/coagulation during conventional microsurgery. While the tool left prong is fixed to the rolling link, the right prong bears a miniaturized drum sector with a large diameter to expand the force scale and resolution. The drum transmits the actuator output torque to the right prong and generates haptic force feedback at the tool level. The tool is also equipped with a hall-effect sensor and magnet bar installed vis-à-vis on the inner side of the two prongs to measure the tooltip distance and provide an analogue signal to the control system. We believe that such a haptic end-effector could significantly increase the accuracy of telerobotic surgery and help avoid high forces that are known to cause bleeding/injury.

Keywords: end-effector, force generation, haptic interface, robotic surgery, surgical tool, tele-operation

Procedia PDF Downloads 113
6425 Biopics in Hindi Film Industry and the Youth Perception

Authors: Divyani Redhu, Sachin Bharti

Abstract:

India, as a nation, has always been known for its concept of ‘Unity in Diversity’, and the same ideology can very well be witnessed in the kind of cinema that is produced in India. From mythological films in the beginning to historical films and from comedy to the all-entertaining commercial ‘masala’ films, the Indian film industry has time and again catered its viewers with varied flavors on screen. Needless to say that for a film industry which stood at a total value of 183.2 billion in the year 2019 as per the Statista Portal 2020, there is no dearth of viewers and at the same time, to cater to the needs of a humongous viewer base, variety in content needs to be offered. Particularly looking at the filmography of the Hindi film industry of the last decade, undoubtedly, the genre that has risen like a shining star is that of Biopics. Hindi cinema’s never-ending fascination with the biopic has grown stronger and become more evident in recent times. The success of biographical films like Jodha Akbar, The Dirty Picture, Mary Kom, Bajirao Mastani, Neerja, Aligarh, Azhar, etc. seems to have truly reinforced the industry’s faith and put Bollywood on a biopic spree. From films on the lives of sportspersons to those of the actors, gangsters, social workers, historical figures, and extraordinary citizens, the industry has left no stone unturned till now. Also, many more biopics are in the pipeline slated to be released soon. Also, when the film viewers are concerned, India is known as the youngest nation in the world where youth constituted about 34% of the country’s population in 2019, making India the country with maximum young people. Thus, the attempt of the researchers is to understand the perception of youth (15-24 years of age as per the UN) towards the biopic films. The above-mentioned study would be quantitative in nature. For the same, a survey would be conducted in the capital city of India, i.e., Delhi. The tool of the survey would be a questionnaire, and the number of respondents would be 200. The results derived from the study would focus on the film viewing preferences of youth in Delhi, the popularity of biopic films among the youth, reasons for watching biopic films and their overall perception about the same, etc.

Keywords: biopics, Delhi, Hindi cinema, India, youth

Procedia PDF Downloads 111
6424 Estimation of Effective Mechanical Properties of Linear Elastic Materials with Voids Due to Volume and Surface Defects

Authors: Sergey A. Lurie, Yury O. Solyaev, Dmitry B. Volkov-Bogorodsky, Alexander V. Volkov

Abstract:

The media with voids is considered and the method of the analytical estimation of the effective mechanical properties in the theory of elastic materials with voids is proposed. The variational model of the porous media is discussed, which is based on the model of the media with fields of conserved dislocations. It is shown that this model is fully consistent with the known model of the linear elastic materials with voids. In the present work, the generalized model of the porous media is proposed in which the specific surface properties are associated with the field of defects-pores in the volume of the deformed body. Unlike typical surface elasticity model, the strain energy density of the considered model includes the special part of the surface energy with the quadratic form of the free distortion tensor. In the result, the non-classical boundary conditions take modified form of the balance equations of volume and surface stresses. The analytical approach is proposed in the present work which allows to receive the simple enough engineering estimations for effective characteristics of the media with free dilatation. In particular, the effective flexural modulus and Poisson's ratio are determined for the problem of a beam pure bending. Here, the known voids elasticity solution was expanded on the generalized model with the surface effects. Received results allow us to compare the deformed state of the porous beam with the equivalent classic beam to introduce effective bending rigidity. Obtained analytical expressions for the effective properties depend on the thickness of the beam as a parameter. It is shown that the flexural modulus of the porous beam is decreased with an increasing of its thickness and the effective Poisson's ratio of the porous beams can take negative values for the certain values of the model parameters. On the other hand, the effective shear modulus is constant under variation of all values of the non-classical model parameters. Solutions received for a beam pure bending and the hydrostatic loading of the porous media are compared. It is shown that an analytical estimation for the bulk modulus of the porous material under hydrostatic compression gives an asymptotic value for the effective bulk modulus of the porous beam in the case of beam thickness increasing. Additionally, it is shown that the scale effects appear due to the surface properties of the porous media. Obtained results allow us to offer the procedure of an experimental identification of the non-classical parameters in the theory of the linear elastic materials with voids based on the bending tests for samples with different thickness. Finally, the problem of implementation of the Saint-Venant hypothesis for the transverse stresses in the porous beam are discussed. These stresses are different from zero in the solution of the voids elasticity theory, but satisfy the integral equilibrium equations. In this work, the exact value of the introduced surface parameter was found, which provides the vanishing of the transverse stresses on the free surfaces of a beam.

Keywords: effective properties, scale effects, surface defects, voids elasticity

Procedia PDF Downloads 406
6423 A Comparative Assessment of Information Value, Fuzzy Expert System Models for Landslide Susceptibility Mapping of Dharamshala and Surrounding, Himachal Pradesh, India

Authors: Kumari Sweta, Ajanta Goswami, Abhilasha Dixit

Abstract:

Landslide is a geomorphic process that plays an essential role in the evolution of the hill-slope and long-term landscape evolution. But its abrupt nature and the associated catastrophic forces of the process can have undesirable socio-economic impacts, like substantial economic losses, fatalities, ecosystem, geomorphologic and infrastructure disturbances. The estimated fatality rate is approximately 1person /100 sq. Km and the average economic loss is more than 550 crores/year in the Himalayan belt due to landslides. This study presents a comparative performance of a statistical bivariate method and a machine learning technique for landslide susceptibility mapping in and around Dharamshala, Himachal Pradesh. The final produced landslide susceptibility maps (LSMs) with better accuracy could be used for land-use planning to prevent future losses. Dharamshala, a part of North-western Himalaya, is one of the fastest-growing tourism hubs with a total population of 30,764 according to the 2011 census and is amongst one of the hundred Indian cities to be developed as a smart city under PM’s Smart Cities Mission. A total of 209 landslide locations were identified in using high-resolution linear imaging self-scanning (LISS IV) data. The thematic maps of parameters influencing landslide occurrence were generated using remote sensing and other ancillary data in the GIS environment. The landslide causative parameters used in the study are slope angle, slope aspect, elevation, curvature, topographic wetness index, relative relief, distance from lineaments, land use land cover, and geology. LSMs were prepared using information value (Info Val), and Fuzzy Expert System (FES) models. Info Val is a statistical bivariate method, in which information values were calculated as the ratio of the landslide pixels per factor class (Si/Ni) to the total landslide pixel per parameter (S/N). Using this information values all parameters were reclassified and then summed in GIS to obtain the landslide susceptibility index (LSI) map. The FES method is a machine learning technique based on ‘mean and neighbour’ strategy for the construction of fuzzifier (input) and defuzzifier (output) membership function (MF) structure, and the FR method is used for formulating if-then rules. Two types of membership structures were utilized for membership function Bell-Gaussian (BG) and Trapezoidal-Triangular (TT). LSI for BG and TT were obtained applying membership function and if-then rules in MATLAB. The final LSMs were spatially and statistically validated. The validation results showed that in terms of accuracy, Info Val (83.4%) is better than BG (83.0%) and TT (82.6%), whereas, in terms of spatial distribution, BG is best. Hence, considering both statistical and spatial accuracy, BG is the most accurate one.

Keywords: bivariate statistical techniques, BG and TT membership structure, fuzzy expert system, information value method, machine learning technique

Procedia PDF Downloads 123
6422 Communication Anxiety in Nigerian Students Studying English as a Foreign Language: Evidence from Colleges of Education Sector

Authors: Yasàlu Haruna

Abstract:

In every transaction, the use of language is central regardless of form or complexity if any meaning is expected to be harvested therefrom. Students constituting a population group in the learning landscape of Nigeria occupy a central position with a propensity to excel or otherwise in the context of communication, especially in the learning process and social interaction. The nature or quantum of anxiety or confidence in speaking a second language is not only peculiar to societies where the second language is not an official language but to a degree, the linguistic gap created by adoption and adaptation syndrome manifests in created anxiety or lack of confidence especially where mastery of a spoken language becomes a major challenge. This paper explores the manner in which linguistic complexity and cultural barriers combine to widen the adaptation and adoption gap. In much the same way, typical issues of pronouncement, intonation and accent difficulties are vital variables that explain the root cause of anxiety. Using a combination of primary and secondary sources of data expressed in questionnaires, key informant interviews and other available data, the paper concludes that the non-integration of anxiety possibility into the education delivery framework has left a lot to be needed in cultivating second language speakers among students of Nigerian Colleges of Education. In addition, cultural barriers and the absence of integration interfaces in the course of learning within and outside the classroom contribute to further widening the gap. Again, colleagues/mates/conversation partners' mastery of a second language remains a contributory factor largely due to the quality of the preparatory school system in many parts of the country. The paper recommends that national policies and frameworks must be reviewed to consider integration windows where culture and conversation partner deficiencies can be remedied through educational events such as debates, quizzes and symposia; improvements can be attained while commercial advertisements are tailored towards seeking for adoption of second language in commerce and major cultural activities.

Keywords: cultural barriers, integration, college of education and adaptation, second language

Procedia PDF Downloads 82
6421 The Impact of Sign Language on Generating and Maintaining a Mental Image

Authors: Yi-Shiuan Chiu

Abstract:

Deaf signers have been found to have better mental image performance than hearing nonsigners. The goal of this study was to investigate the ability to generate mental images, to maintain them, and to manipulate them in deaf signers of Taiwanese Sign Language (TSL). In the visual image task, participants first memorized digits formed in a cell of 4 × 5 grids. After presenting a cue of Chinese digit character shown on the top of a blank cell, participants had to form a corresponding digit. When showing a probe, which was a grid containing a red circle, participants had to decide as quickly as possible whether the probe would have been covered by the mental image of the digit. The ISI (interstimulus interval) between cue and probe was manipulated. In experiment 1, 24 deaf signers and 24 hearing nonsigners were asked to perform image generation tasks (ISI: 200, 400 ms) and image maintenance tasks (ISI: 800, 2000 ms). The results showed that deaf signers had had an enhanced ability to generate and maintain a mental image. To explore the process of mental image, in experiment 2, 30 deaf signers and 30 hearing nonsigners were asked to do visual searching when maintaining a mental image. Between a digit image cue and a red circle probe, participants were asked to search a visual search task to see if a target triangle apex was directed to the right or left. When there was only one triangle in the searching task, the results showed that both deaf signers and hearing non-signers had similar visual searching performance in which the searching targets in the mental image locations got facilitates. However, deaf signers could maintain better and faster mental image performance than nonsigners. In experiment 3, we increased the number of triangles to 4 to raise the difficulty of the visual search task. The results showed that deaf participants performed more accurately in visual search and image maintenance tasks. The results suggested that people may use eye movements as a mnemonic strategy to maintain the mental image. And deaf signers had enhanced abilities to resist the interference of eye movements in the situation of fewer distractors. In sum, these findings suggested that deaf signers had enhanced mental image processing.

Keywords: deaf signers, image maintain, mental image, visual search

Procedia PDF Downloads 147
6420 Submarine Topography and Beach Survey of Gang-Neung Port in South Korea, Using Multi-Beam Echo Sounder and Shipborne Mobile Light Detection and Ranging System

Authors: Won Hyuck Kim, Chang Hwan Kim, Hyun Wook Kim, Myoung Hoon Lee, Chan Hong Park, Hyeon Yeong Park

Abstract:

We conducted submarine topography & beach survey from December 2015 and January 2016 using multi-beam echo sounder EM3001(Kongsberg corporation) & Shipborne Mobile LiDAR System. Our survey area were the Anmok beach in Gangneung, South Korea. We made Shipborne Mobile LiDAR System for these survey. Shipborne Mobile LiDAR System includes LiDAR (RIEGL LMS-420i), IMU ((Inertial Measurement Unit, MAGUS Inertial+) and RTKGNSS (Real Time Kinematic Global Navigation Satellite System, LEIAC GS 15 GS25) for beach's measurement, LiDAR's motion compensation & precise position. Shipborne Mobile LiDAR System scans beach on the movable vessel using the laser. We mounted Shipborne Mobile LiDAR System on the top of the vessel. Before beach survey, we conducted eight circles IMU calibration survey for stabilizing heading of IMU. This exploration should be as close as possible to the beach. But our vessel could not come closer to the beach because of latency objects in the water. At the same time, we conduct submarine topography survey using multi-beam echo sounder EM3001. A multi-beam echo sounder is a device observing and recording the submarine topography using sound wave. We mounted multi-beam echo sounder on left side of the vessel. We were equipped with a motion sensor, DGNSS (Differential Global Navigation Satellite System), and SV (Sound velocity) sensor for the vessel's motion compensation, vessel's position, and the velocity of sound of seawater. Shipborne Mobile LiDAR System was able to reduce the consuming time of beach survey rather than previous conventional methods of beach survey.

Keywords: Anmok, beach survey, Shipborne Mobile LiDAR System, submarine topography

Procedia PDF Downloads 420
6419 Well-Being and Helping Technology for Retired Population in Finland

Authors: R. Pääkkönen, L. Korpinen

Abstract:

This study aimed to evaluate parameters influencing well-being and how to maintain well-being as long as possible after retirement. There is contradictory information on the health changes after retirement in Finland. This work is based on interviews, statistics, and literature evaluation of Finland. Most often, balance, multitasking reaction time, and adaptation of vision in dim and darks areas are worsened. Slowing is one characteristic that is difficult to measure properly. The most important is try to determine ways to manage daily activities and symptoms of disease after retirement. Medicine is advancing, problems are often also on the economic side. Information of technical aids is important. It is worth planning a retirement age.

Keywords: retirement, working, aging, wellness

Procedia PDF Downloads 234
6418 Dynamic Model for Forecasting Rainfall Induced Landslides

Authors: R. Premasiri, W. A. H. A. Abeygunasekara, S. M. Hewavidana, T. Jananthan, R. M. S. Madawala, K. Vaheeshan

Abstract:

Forecasting the potential for disastrous events such as landslides has become one of the major necessities in the current world. Most of all, the landslides occurred in Sri Lanka are found to be triggered mostly by intense rainfall events. The study area is the landslide near Gerandiella waterfall which is located by the 41st kilometer post on Nuwara Eliya-Gampala main road in Kotmale Division in Sri Lanka. The landslide endangers the entire Kotmale town beneath the slope. Geographic Information System (GIS) platform is very much useful when it comes to the need of emulating the real-world processes. The models are used in a wide array of applications ranging from simple evaluations to the levels of forecast future events. This project investigates the possibility of developing a dynamic model to map the spatial distribution of the slope stability. The model incorporates several theoretical models including the infinite slope model, Green Ampt infiltration model and Perched ground water flow model. A series of rainfall values can be fed to the model as the main input to simulate the dynamics of slope stability. Hydrological model developed using GIS is used to quantify the perched water table height, which is one of the most critical parameters affecting the slope stability. Infinite slope stability model is used to quantify the degree of slope stability in terms of factor of safety. DEM was built with the use of digitized contour data. Stratigraphy was modeled in Surfer using borehole data and resistivity images. Data available from rainfall gauges and piezometers were used in calibrating the model. During the calibration, the parameters were adjusted until a good fit between the simulated ground water levels and the piezometer readings was obtained. This model equipped with the predicted rainfall values can be used to forecast of the slope dynamics of the area of interest. Therefore it can be investigated the slope stability of rainfall induced landslides by adjusting temporal dimensions.

Keywords: factor of safety, geographic information system, hydrological model, slope stability

Procedia PDF Downloads 419
6417 Field Emission Scanning Microscope Image Analysis for Porosity Characterization of Autoclaved Aerated Concrete

Authors: Venuka Kuruwita Arachchige Don, Mohamed Shaheen, Chris Goodier

Abstract:

Aerated autoclaved concrete (AAC) is known for its lightweight, easy handling, high thermal insulation, and extremely porous structure. Investigation of pore behavior in AAC is crucial for characterizing the material, standardizing design and production techniques, enhancing the mechanical, durability, and thermal performance, studying the effectiveness of protective measures, and analyzing the effects of weather conditions. The significant details of pores are complicated to observe with acknowledged accuracy. The High-resolution Field Emission Scanning Electron Microscope (FESEM) image analysis is a promising technique for investigating the pore behavior and density of AAC, which is adopted in this study. Mercury intrusion porosimeter and gas pycnometer were employed to characterize porosity distribution and density parameters. The analysis considered three different densities of AAC blocks and three layers in the altitude direction within each block. A set of understandings was presented to extract and analyze the details of pore shape, pore size, pore connectivity, and pore percentages from FESEM images of AAC. Average pore behavior outcomes per unit area were presented. Comparison of porosity distribution and density parameters revealed significant variations. FESEM imaging offered unparalleled insights into porosity behavior, surpassing the capabilities of other techniques. The analysis conducted from a multi-staged approach provides porosity percentage occupied by various pore categories, total porosity, variation of pore distribution compared to AAC densities and layers, number of two-dimensional and three-dimensional pores, variation of apparent and matrix densities concerning pore behaviors, variation of pore behavior with respect to aluminum content, and relationship among shape, diameter, connectivity, and percentage in each pore classification.

Keywords: autoclaved aerated concrete, density, imaging technique, microstructure, porosity behavior

Procedia PDF Downloads 55
6416 Approaches to Estimating the Radiation and Socio-Economic Consequences of the Fukushima Daiichi Nuclear Power Plant Accident Using the Data Available in the Public Domain

Authors: Dmitry Aron

Abstract:

Major radiation accidents carry not only the potential risks of negative consequences for public health due to exposure but also because of large-scale emergency measures were taken by authorities to protect the population, which can lead to unreasonable social and economic damage. It is technically difficult, as a rule, to assess the possible costs and damages from decisions on evacuation or resettlement of residents in the shortest possible time, since it requires specially prepared information systems containing relevant information on demographic, economic parameters and incoming data on radiation conditions. Foreign observers also face the difficulties in assessing the consequences of an accident in a foreign territory, since they usually do not have official and detailed statistical data on the territory of foreign state beforehand. Also, they can suppose the application of unofficial data from open Internet sources is an unreliable and overly labor-consuming procedure. This paper describes an approach to prompt creation of relational database that contains detailed actual data on economics, demographics and radiation situation at the Fukushima Prefecture during the Fukushima Daiichi NPP accident, received by the author from open Internet sources. This database was developed and used to assess the number of evacuated population, radiation doses, expected financial losses and other parameters of the affected areas. The costs for the areas with temporarily evacuated and long-term resettled population were investigated, and the radiological and economic effectiveness of the measures taken to protect the population was estimated. Some of the results are presented in the article. The study showed that such a tool for analyzing the consequences of radiation accidents can be prepared in a short space of time for the entire territory of Japan, and it can serve for the modeling of social and economic consequences for hypothetical accidents for any nuclear power plant in its territory.

Keywords: Fukushima, radiation accident, emergency measures, database

Procedia PDF Downloads 188
6415 Photoluminescence of Barium and Lithium Silicate Glasses and Glass Ceramics Doped with Rare Earth Ions

Authors: Augustas Vaitkevicius, Mikhail Korjik, Eugene Tretyak, Ekaterina Trusova, Gintautas Tamulaitis

Abstract:

Silicate materials are widely used as luminescent materials in amorphous and crystalline phase. Lithium silicate glass is popular for making neutron sensitive scintillation glasses. Cerium-doped single crystalline silicates of rare earth elements and yttrium have been demonstrated to be good scintillation materials. Due to their high thermal and photo-stability, silicate glass ceramics are supposed to be suitable materials for producing light converters for high power white light emitting diodes. In this report, the influence of glass composition and crystallization on photoluminescence (PL) of different silicate glasses was studied. Barium (BaO-2SiO₂) and lithium (Li₂O-2SiO₂) glasses were under study. Cerium, dysprosium, erbium and europium ions as well as their combinations were used for doping. The influence of crystallization was studied after transforming the doped glasses into glass ceramics by heat treatment in the temperature range of 550-850 degrees Celsius for 1 hour. The study was carried out by comparing the photoluminescence (PL) spectra, spatial distributions of PL parameters and quantum efficiency in the samples under study. The PL spectra and spatial distributions of their parameters were obtained by using confocal PL microscopy. A WITec Alpha300 S confocal microscope coupled with an air cooled CCD camera was used. A CW laser diode emitting at 405 nm was exploited for excitation. The spatial resolution was in sub-micrometer domain in plane and ~1 micrometer perpendicularly to the sample surface. An integrating sphere with a xenon lamp coupled with a monochromator was used to measure the external quantum efficiency. All measurements were performed at room temperature. Chromatic properties of the light emission from the glasses and glass ceramics have been evaluated. We observed that the quantum efficiency of the glass ceramics is higher than that of the corresponding glass. The investigation of spatial distributions of PL parameters revealed that heat treatment of the glasses leads to a decrease in sample homogeneity. In the case of BaO-2SiO₂: Eu, 10 micrometer long needle-like objects are formed, when transforming the glass into glass ceramics. The comparison of PL spectra from within and outside the needle-like structure reveals that the ratio between intensities of PL bands associated with Eu²⁺ and Eu³⁺ ions is larger in the bright needle-like structures. This indicates a higher degree of crystallinity in the needle-like objects. We observed that the spectral positions of the PL bands are the same in the background and the needle-like areas, indicating that heat treatment imposes no significant change to the valence state of the europium ions. The evaluation of chromatic properties confirms applicability of the glasses under study for fabrication of white light sources with high thermal stability. The ability to combine barium and lithium glass matrixes and doping by Eu, Ce, Dy, and Tb enables optimization of chromatic properties.

Keywords: glass ceramics, luminescence, phosphor, silicate

Procedia PDF Downloads 310
6414 The Effect of Parameters on Production of NİO/Al2O3/B2O3/SiO2 Composite Nanofibers by Using Sol-Gel Processing and Electrospinning Technique

Authors: F. Sevim, E. Sevimli, F. Demir, T. Çalban

Abstract:

For the first time, nanofibers of PVA /nickel nitrate/silica/alumina izopropoxide/boric acid composite were prepared by using sol-gel processing and electrospinning technique. By high temperature calcinations of the above precursor fibers, nanofibers of NiO/Al2O3/B2O3/SiO2 composite with diameters of 500 nm could be successfully obtained. The fibers were characterized by TG/DTA, FT-IR, XRD and SEM analyses.

Keywords: nano fibers, NiO/Al2O3/B2O3/SiO2 composite, sol-gel processing, electro spinning

Procedia PDF Downloads 332