Search results for: permanent teeth

Authors: Ghada Salem, Nihal Kabel

Abstract:

Objective: This in vitro study was carried out to assess the microleakage properties of nano-filled glass ionomer in comparison to resin-reinforced glass ionomers. Material and Methods: 40 deciduous molar teeth were included in this study. Class-II cavity was prepared in a standard form for all the specimens. The teeth were randomly distributed into two groups (20 per group) according to the restorative material used either nano-glass ionomer or Photac Fill glass ionomer restoration. All specimens were thermocycled for 1000 cycles between 5 and 55 °C. After that, the teeth were immersed in 2% methylene blue dye then sectioned and evaluated under a stereomicroscope. Microleakage was assessed using linear dye penetration and on a scale from zero to five. Results: Two way ANOVA test revealed a statistically significant lower degree of microleakage in both occlusal and gingival restorations (0.4±0.2), (0.9±0.1) for nano-filled glass ionomer group in comparison to resin modified glass ionomer (2.3±0.7), (2.4±0.5). No statistical difference was found between gingival and occlusal leakage regarding the effect of the measured site. Conclusion: Nano-filled glass ionomer shows superior sealing ability which enables this type of restoration to be used in minimum invasive treatment.

Keywords: microleakage, nanoionomer, resin-reinforced glass ionomer, proximal cavity preparation

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Authors: Ramakrishna Rao Mamidi

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It is essential for Surface Mounted Permanent Magnet (SMPM) generators to determine the performance prediction and analyze the magnet’s air gap flux density wave shape. The flux density wave shape is neither a pure sine wave or square wave nor a combination. This is due to the variation of air gap reluctance between the stator and permanent magnets. The stator slot openings and the number of slots make the wave shape highly complicated. To reduce the complexity of analysis, approximations are made to the wave shape using Fourier analysis. In contrast to the traditional integration method, the Fourier coefficients, an and bn, are obtained by direct search method optimization. The wave shape with optimized coefficients gives a wave shape close to the desired wave shape. Harmonics amplitudes are worked out and compared with initial values. It can be concluded that the direct search method can be used for estimating Fourier coefficients for irregular wave shapes.

Keywords: direct search, flux plot, fourier analysis, permanent magnets

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Authors: M. Naeimi, H. Aghazadeh, E. Afjei, A. Siadatan

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In this paper, a novel view of air gap magnetic field analysis of synchronous reluctance motor and permanent magnet assisted synchronous reluctance motor under static eccentricity to provide the precise fault diagnosis based on three-dimensional finite element method is presented. Analytical nature of this method makes it possible to simulate reliable and precise model by considering the end effects and axial fringing effects. The results of the three-dimensional finite element analysis of synchronous reluctance motor and permanent magnet synchronous reluctance motor such as flux linkage, flux density, and compression both of SynRM and PM-SynRM for various eccentric motor conditions are obtained and analyzed. These results present useful information regarding to the detection of static eccentricity.

Keywords: synchronous reluctance motor (SynRM), permanent magnet assisted synchronous reluctance motor (PMaSynRM), finite element method, static eccentricity, fault analysis

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Authors: M. Barański

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This paper presents a several diagnostic methods designed to electrical machines especially for permanent magnets (PM) machines. Those machines are commonly used in small wind and water systems and vehicles drives. Those methods are preferred by the author in periodic diagnostic of electrical machines. The special attention should be paid to diagnostic method of turn-to-turn insulation and vibrations. Both of those methods were created in Institute of Electrical Drives and Machines Komel. The vibration diagnostic method is the main thesis of author’s doctoral dissertation. This is method of determination the technical condition of PM electrical machine basing on its own signals is the subject of patent application No P.405669. Specific structural properties of machines excited by permanent magnets are used in this method - electromotive force (EMF) generated due to vibrations. There was analysed number of publications which describe vibration diagnostic methods and tests of electrical machines with permanent magnets and there was no method found to determine the technical condition of such machine basing on their own signals.

Keywords: electrical vehicle, generator, main insulation, permanent magnet, thermography, turn-to-traction drive, turn insulation, vibrations

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Authors: Mohamed Moustafa Mahmoud Sedky

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In line start permanent magnet synchronous motor, eccentricity is a common fault that can make it necessary to remove the motor from the production line. However, because the motor may be inaccessible, diagnosing the fault is not easy. This paper presents an FEM that identifies different models, static eccentricity, dynamic eccentricity, and mixed eccentricity, at no load and full load. The method overcomes the difficulty of applying FEMs to transient behavior. It simulates motor speed, torque and flux density distribution along the air gap for SE, DE, and ME. This paper represents the various effects of different eccentricities types on the transient performance.

Keywords: line start permanent magnet, synchronous machine, static eccentricity, dynamic eccentricity, mixed eccentricity

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Authors: Yassa Nacera, Badji Abderrezak, Saidoune Abdelmalek, Houassine Hamza

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Several kinds of faults can occur in a permanent magnet synchronous machine (PMSM) systems: bearing faults, electrically short/open faults, eccentricity faults, and demagnetization faults. Demagnetization fault means that the strengths of permanent magnets (PM) in PMSM decrease, and it causes low output torque, which is undesirable for EVs. The fault is caused by physical damage, high-temperature stress, inverse magnetic field, and aging. Motor current signature analysis (MCSA) is a conventional motor fault detection method based on the extraction of signal features from stator current. a simulation model of the PMSM under partial demagnetization and uniform demagnetization fault was established, and different degrees of demagnetization fault were simulated. The harmonic analyses using the Fast Fourier Transform (FFT) show that the fault diagnosis method based on the harmonic wave analysis is only suitable for partial demagnetization fault of the PMSM and does not apply to uniform demagnetization fault of the PMSM.

Keywords: permanent magnet, diagnosis, demagnetization, modelling

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Authors: Pawel Pistelok

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The article presents the concept of an electromagnetic circuit of a 3-phase surface-mounted permanent magnet generator designed for a single phase operation. A cross section of electromagnetic circuit and a field-circuit model of generator used for computations are shown. The paper presents comparative analysis of simulation results obtained for two different versions of generator regarding construction of armature winding. In the first version of generator the voltages generated in each of three winding phases have different rms values (different number of turns in each of phases), three winding phases are connected in series and one phase load is connected to the two output terminals of generator. The second version of generator is very similar, i.e. three winding phases are connected in series and one phase load is powered by generator, but in this version the voltages generated in each of winding phases have exactly the same rms values (the same number of turns in each of phases). The time waveforms of voltages, currents and electromagnetic torques in the airgaps of two machine versions for rated power are shown.

Keywords: permanent magnet generator, permanent magnets, synchronous generator, vibration, course of torque, single phase work, unsymmetrical operation point, serial connection of winding phase

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Authors: Yang-Gyun Kim, Eun-Taek Woo, Myeong-Gon Lee, Yun-Hyun Cho, Seung-Ho Han

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For the sustainable development of wind energy, energy industries have invested in the development of highly efficient wind turbines such as an axial flux permanent magnet (AFPM) generator. The AFPM generator, however, has a history of overheating on the surface of the stator, so that power production decreases significantly. A proper cooling system, therefore, is needed. Although a convective-type cooling system has been developed, the size of the air blower must be increased when the generator’s capacity exceeds 2.5 MW. In this paper, we proposed a newly developed conductive-type cooling system using a heat pipe wound to the stator of a 2.5 MW AFPM generator installed on an offshore wind turbine. The numerical results showed that the temperatures on the stator surface using convective-type cooling system and the proposed conductive-type cooling system at thermal saturation were 60 and 76°C, respectively, which met the requirements for power production. The temperatures of the permanent magnet cased by the radiant heating from the stator surface were 53°C and 66°C, respectively, in each case. As a result, the permanent magnet did not reach the malfunction temperature. Although the cooling temperatures in the case of the conductive-type cooling system were higher than that of the convective-type cooling system, the relatively small size of the water pump and radiators make a light-weight design of the AFPM generator possible.

Keywords: wind turbine, axial flux permanent magnet (AFPM) generator, conductive-type cooling system

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Authors: Yusuf Yasa, Erkan Mese

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This paper investigates the thermal issue of permanent magnet synchronous generator which is frequently used in direct drive gearless small-scale wind turbine applications. Permanent magnet synchronous generator (PMSG) is designed with 2.5 kW continuous and 6 kW peak power. Then considering generator geometry, mechanical design of wind turbine is performed. Thermal analysis and optimization is carried out considering all wind turbine components to reach realistic results. These issue is extremely important in research and development(R&D) process for wind turbine applications.

Keywords: direct drive, gearless wind turbine, permanent magnet synchronous generator (PMSG), small-scale wind turbine, thermal management

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Authors: Mimoza Canga, Irene Malagnino, Ruzhdie Qafmolla, Vergjini Mulo, Gresa Baboci, Vito Antonio Malagnino

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Background: Dental caries represents the most widespread pathology in childhood. The prevalence of dental caries varies with age, gender, socio economic status, geographical location, nutrition habits, and oral hygiene. Objective: The objective of the present longitudinal study is to show clearly the prevalence of dental caries in the children of age 6 and 7 years old in Vlore, Albania, in a two year time period with controls done every 6 months. Materials and methods: The present study was conducted on 530 children, with a controlled sample for a time period of 24 months from September 2019- September 2021. The children in the study had different economic and social backgrounds. The teeth controls were done by the dentists who work at the hospital of the city. The present study was conducted in accordance with Helsinki declaration. Permissions were obtained in written form, which allowed us to perform the observations. Parents had the right to withdraw their children at any time. Statistical analysis was performed using IBM SPSS Statistics 23.0. The significance level (α) was set at 0.05, whereas P-value and analysis of variance (ANOVA) were used to analyze the data. Results: The data of the present study showed that the age group of 6 years old had 139 or 52.3% of the children with dental caries and 127 or 47.7% of them had no dental caries, while at the age of 7 there were 184 or 69.7% of the children with dental caries problems in the permanent molars and 80 or 30.3% of them had no dental caries. In the present study, it was observed that there is a statistically significant association between age group and presence of caries. Children 7 years old had higher presence of dental caries (χ2 = 16.934 (df 1) p-value < 0.001). According to the present research, there is a statistically significant correlation between period of time and the presence of dental caries. Furthermore, in the actual research, it was established that in the time 18-24 months, the prevalence of dental caries was high (χ2=15,318 (df 1) p-value = 0.004). Conclusion: According to the results of the present study performed in Albania in a two year time period with controls done every 6 months, it is proved that the prevalence of dental caries was 17.4 percent higher among children 7 years old in comparison with the children 6 years old.

Keywords: age, children, dental caries, permanent molars

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Authors: Jasbir Arora, Indu Talwar, Daisy Sahni, Vidya Rattan

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Introduction: Age estimation is a crucial step to build the identity of a person, both in case of deceased and alive. In adults, age can be estimated on the basis of six regressive (Attrition, Secondary dentine, Dentine transparency, Root resorption, Cementum apposition and Periodontal Disease) changes in teeth qualitatively using scoring system and quantitatively by micrometric method. The present research was designed to establish the reliability of qualitative (method 1) and quantitative (method 2) of age estimation among North Indians and to compare the efficacy of these two methods. Method: 250 single-rooted extracted teeth (18-75 yrs.) were collected from Department of Oral Health Sciences, PGIMER, Chandigarh. Before extraction, periodontal score of each tooth was noted. Labiolingual sections were prepared and examined under light microscope for regressive changes. Each parameter was scored using Gustafson’s 0-3 point score system (qualitative), and total score was calculated. For quantitative method, each regressive change was measured quantitatively in form of 18 micrometric parameters under microscope with the help of measuring eyepiece. Age was estimated using linear and multiple regression analysis in Gustafson’s method and Kedici’s method respectively. Estimated age was compared with actual age on the basis of absolute mean error. Results: In pooled data, by Gustafson’s method, significant correlation (r= 0.8) was observed between total score and actual age. Total score generated an absolute mean error of ±7.8 years. Whereas, for Kedici’s method, a value of correlation coefficient of r=0.5 (p<0.01) was observed between all the eighteen micrometric parameters and known age. Using multiple regression equation, age was estimated, and an absolute mean error of age was found to be ±12.18 years. Conclusion: Gustafson’s (qualitative) method was found to be a better predictor for age estimation among North Indians.

Keywords: forensic odontology, age estimation, North India, teeth

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Authors: Raja V., Chokkalingam B.

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For rough cutting, in many industries and educational institutions using carbon steels or HSS single point cutting tools in center lathe machine. In power hacksaw blades, only the cutter teeth region used to parting off the given material. The portions other than the teeth can be used as a single point cutting tool for rough turning and facing on soft materials. The hardness and Tensile strength of this used Power hacksaw blade is almost same as conventional cutting tools. In this paper, the effect of power hacksaw blades over conventional tool has been compared. Thickness of the blade (1.6 mm) is very small compared to its length and width. Hence, a special tool holding device is designed to hold the tool.

Keywords: hardness, high speed steels, power hacksaw blade, tensile strength

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Authors: Jeremy Berry, Shannon Rodrigue, Caroline Norris

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This study explores the impact of tattoos and/or brands on the recovery of sex trafficking survivors. Many victims of sex trafficking are forced or coerced to take markings of ownership while in the sex trafficking trade in the form of painful tattoos or brands. As a result, victims who are rescued and in recovery often must live with permanent reminders of their traumatic experiences or are left to resort to expensive cosmetic or cover-up jobs, which for many are out of reach. As is often true of domestic violence victims who are left with scars from their abusers, the impact of these permanent markers can delay the healing process and contribute to post-traumatic stress. This study tells the story from the perspectives of the survivors of sex trafficking, how these specific permanent reminders impacted their healing. The study employs a thematic analysis of interviews with sex trafficking victims via focus group interviews.

Keywords: sex trafficking, tattoos, trauma, healing

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Authors: B. Nair, S. Singh

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Oral health behaviors such as dietary preferences and tooth brushing are acquired during a child’s primary socialization period yet many oral health promotion interventions are implemented without taking into account the role and impact of parental influence in supporting healthy oral health behaviors. The aim and objective of this study was to determine the relationship between parental income and level of education with knowledge, attitudes and perceptions of oral health care practices. Methods: The study design was cross-sectional and exploratory, and data collection occurred in two phases. Phase 1 comprised of a self-administered questionnaire. The sample consisted of parents of 313 Grade 1 learners aged between 5-6 years old attending one of twelve selected public primary schools in the Chatsworth Circuit, Durban, South Africa. Phase 2 comprised of focus group discussions held at 5 purposively selected schools. Data collection comprised of a semi-structured face-to-face group interview with the objective of obtaining a deeper understanding of parental knowledge, attitudes and perceptions of dental caries. Results and Discussion: Almost 56% of participants earned a monthly income of less than R6000 (600 US dollars). Nearly three quarters (77.5%) of participants indicated that they did not have medical aid/insurance scheme. More than three-quarters of the participants (76.6%) identified diet as being the primary cause of decayed teeth. More than half of the study sample (56.1%) indicated that milk teeth were important and that rotten teeth (74.6%) could affect the child’s health. Almost half (49.8%) of participants reported that “bad teeth” were inherited. With more than two-thirds of the participants (77.7%), having at most a high school education, there was a correlation between the level of the caregiver’s education and the oral health care of the child. The analysis of the correlation between a child having decayed teeth and income (p=.007); and the manner in which the income is received (p=.003) was statistically significant. The results indicate that more effort needs to be placed in understanding parental knowledge, perceptions and attitudes towards dental caries. Parental level of education, income and oral health literacy is shown to be related to attitudes, and perceptions towards dental caries and its subsequent preventive measures. These findings have important implications for oral health planning at community and facility-based levels.

Keywords: oral health prevention, parental education, dental caries, attitudes and perceptions

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Authors: Soheil Heydari, Ailar Hajimohammadi, Nasser Khalili

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Polystyrene, being made from a monomer called styrene, is a rigid and easy-to mould polymer that is widely used for many applications, from foam packaging to disposable containers. Considering that the degradation of waste polystyrene takes up to 500 years, there is an urgent need for a sustainable application for waste polystyrene. This study evaluates the application of waste polystyrene as an asphalt modifier. The inclusion of waste plastics in asphalt is either practised by the dry process or the wet process. In the dry process, plastics are added straight into the asphalt mixture and in the wet process, they are mixed and digested into bitumen. In this article, polystyrene was used as an asphalt modifier in a dry process. However, the mixing process is precisely designed to make sure that the polymer is melted and modified in the binder. It was expected that, due to the rigidity of polystyrene, it will have positive effects on the permanent deformation of the asphalt mixture. Therefore, different mixtures were manufactured with different contents of polystyrene and Marshall specimens were manufactured, and dynamic creep tests were conducted to evaluate the permanent deformation of the modification. This is a commonly repeated loading test conducted at different stress levels and temperatures. Loading cycles are applied to the AC specimen until failure occurs; with the amount of deformation constantly recorded the cumulative, permanent strain is determined and reported as a function of the number of cycles. Also, to our best knowledge, hybrid mixes of polystyrene with crumb rubber and low-density polyethylene were made and compared with a polystyrene-modified mixture. The test results of this study showed that the hybrid mix of polystyrene and low-density polyethylene has the highest resistance against permanent deformation. However, the polystyrene-modified mixture outperformed the hybrid mix of polystyrene and crumb rubber, and both demonstrated way lower permanent deformation than the unmodified specimen.

Keywords: permanent deformation, waste plastics, polystyrene, hybrid plastics, hybrid mix, hybrid modification, dry process

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Authors: Nunthawan Nowwarote, Waleerat Sukarawan, Prasit Pavasant, Thanaphum Osathanon

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Interleukin 6 (IL-6) is a multifunctional cytokine, regulating various biological responses in several tissues. A Recent study shows that IL-6 plays a role in stemness maintenance in stem cells isolated from human exfoliated deciduous teeth (SHEDs). However, the role of IL-6 on cell differentiation in SHEDs remains unknown. The present study investigated the effect of IL-6 on SHEDs differentiation. Cells were isolated from dental pulp tissues of human deciduous teeth. Flow cytometry was used to determined mesenchymal stem cell marker expression, and the multipotential differentiation (osteogenic, adipogenic and neurogenic lineage ) was also determined. The mRNA was determined using real-time quantitative polymerase chain reaction, and the phenotypes were confirmed by chemical and immunofluorescence staining. Results demonstrated that SHEDs expressed CD44, CD73, CD90, CD105 but not CD45. Further, the up-regulation of osteogenic, adipogenic and neurogenic marker genes was observed upon maintaining cells in osteogenic, adipogenic and neurogenic induction medium, respectively. The addition of IL-6 induced osteogenic by up-regulated osteogenic marker gene also increased in vitro mineralization. Under neurogenic medium supplement with IL-6, up-regulated neurogenic marker. Whereas, an addition of IL-6 attenuated adipogenic differentiation by SHEDs. In conclusion, this evidence implies that IL-6 may participate in cells differentiation ability of SHEDs.

Keywords: SHEDs, IL-6, cell differentiations, dental pulp

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Authors: Rasha F. Sharaf

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Treatment of dental caries in young children is considered a great challenge for all dentists, especially with uncooperative children. Recently non-invasive techniques have been highlighted as they alleviate the need for local anesthesia and other painful procedures during management of carious teeth and, at the same time, increase the success rate of the treatment done. Silver Diamine Fluoride (SDF) is one of the most effective cariostatic materials that arrest the progression of carious lesions and aid in remineralizing the demineralized tooth structure. Both fluoride and silver ions proved to have an antibacterial action and aid in the precipitation of an insoluble layer that prevents further decay. At the same time, Moringa proved to have an effective antibacterial action against different types of bacteria, therefore, it can be used as a non-invasive technique for the management of caries in children. One of the important theories for the control of caries is by depriving the cariogenic bacteria from nutrients causing their starvation and death, which can be achieved by applying stainless steel crown on primary molars with carious lesions which are not involving the pulp, and this technique is known as Hall technique. The success rate of the Hall technique can be increased by arresting the carious lesion using either SDF or Moringa and gaining the benefit of their antibacterial action. Multiple clinical cases with 1 year follow up will be presented, comparing different treatment options, and using various materials and techniques for non-invasive and non-painful management of carious primary teeth.

Keywords: SDF, hall technique, carious primary teeth, moringa extract

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Authors: Jenn-Yih Chen, Bean-Yin Lee, Yuan-Chuan Hsu, Jui-Cheng Lin, Kuang-Chyi Lee

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In this paper, a sliding mode control method based on the passivity approach is proposed to control the position of surface-mounted permanent magnet synchronous motors (PMSMs). Firstly, the dynamics of a PMSM was proved to be strictly passive. The position controller with an adaptive law was used to estimate the load torque to eliminate the chattering effects associated with the conventional sliding mode controller. The stability analysis of the overall position control system was carried out by adopting the passivity theorem instead of Lyapunov-type arguments. Finally, experimental results were provided to show that the good position tracking can be obtained, and exhibit robustness in the variations of the motor parameters and load torque disturbances.

Keywords: adaptive law, passivity theorem, permanent magnet synchronous motor, sliding mode control

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Authors: Sadeep Sasidharan, T. B. Isha

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Modern day electric vehicles require compact high torque/power density motors for electric propulsion. This necessitates proper thermal management of the electric motors. The main focus of this paper is to compare the steady state thermal analysis of a conventional 20 kW 8/6 Switched Reluctance Motor (SRM) with that of an Induction Motor and Inset Permanent Magnet (IPM) motor of the same rating. The goal is to develop a proper thermal model of the three types of models for Finite Element Thermal Analysis. JMAG software is used for the development and simulation of the thermal models. The results show that the induction motor is subjected to more heating when used for electric vehicle application constantly, compared to the SRM and IPM.

Keywords: electric vehicles, induction motor, inset permanent magnet motor, loss models, switched reluctance motor, thermal analysis

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Authors: Mahboobe Daneshvar

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Introduction: Clinical studies on the effect of systemic conditions on periodontal diseases have shown that some systemic deficiencies may provide grounds for the onset of periodontal diseases. One of these systemic problems is osteoporosis, which may be a risk factor for the onset and exacerbation of periodontitis. This study tends to evaluate periodontal indices in osteoporotic menopausal women and compare them with healthy controls. Materials and Methods: In this case-control study, participants included 45-75-year-old menopausal women referred to rheumatology wards of the Khatamolanbia Clinic and Shahid Sadoughi Hospital in Yazd; Their bone density was determined by DEXA-scan and by imaging the femoral-lumbar bone. Thirty patients with osteoporosis and 30 subjects with normal BMD were selected. Then, informed consent was obtained for participation in the study. During the clinical examinations, tooth loss (TL), plaque index (PI), gingival recession, pocket probing depth (PPD), clinical attachment loss (CAL), and tooth mobility (TM) were measured to evaluate the periodontal status. These clinical examinations were performed to determine the periodontal status by catheter, mirror and probe. Results: During the evaluation, there was no significant difference in PPD, PI, TM, gingival recession, and CAL between case and control groups (P-value>0.05); that is, osteoporosis has no effect on the above factors. These periodontal factors are almost the same in both healthy and patient groups. In the case of missing teeth, the following results were obtained: the mean of missing teeth was 22.173% of the total teeth in the case group and 18.583% of the total teeth in the control group. In the study of the missing teeth in the case and control groups, there was a significant relationship between case and control groups (P-value = 0.025). Conclusion: In fact, since periodontal disease is multifactorial and microbial plaque is the main cause, osteoporosis is considered a predisposing factor in exacerbation or persistence of periodontal disease. In patients with osteoporosis, usually pathological fractures, hormonal changes, and aging lead to reduced physical activity and affect oral health, which leads to the manifestation of periodontal disease. But this disease increases tooth loss by changing the shape and structure of bone trabeculae and weakening them. Osteoporosis does not seem to be a deterministic factor in the incidence of periodontal disease, since it affects bone quality rather than bone quantity.

Keywords: plaque index, Osteoporosis, tooth mobility, periodontal packet

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Authors: Zeynep Karakoc, Hasan Ilhan Mutaf

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Plaque removal efficacy of different dental brushes and mouth wash during fixed orthodontic appliance therapy was evaluated in this single-blind, crossover and prospective study. Thirty orthodontic patients aged 18 and over undergoing fixed appliance therapy at the end of leveling stage were divided into three groups. Subjects brushed their teeth with a toothbrush under standardized conditions for a period of 30 days prior to inter-dental care products. The same procedure was repeated each time with a different, randomly assigned inter-dental care products in a crossover design. (Inter-dental brush, powered inter-dental brush and mouth wash). At start and end of each removal period, plaque indexes of participants were scored. Each brush achieved statistically significant plaque removal; however, there were no statistical differences among groups for all surfaces of teeth when the plaque score was evaluated. The mouth wash group presented significant improvement in reduction of visible plaque on mesial and distal surfaces of posterior teeth. (-60.9 %, P< .001) Plaque removal for right and left side of mouth showed no significant differences within groups, only mouth wash was more efficient in right side than left side. It is concluded that effectiveness of plaque removal may not be related to the kind of inter-dental products directly. However, toothbrush when used with inter-dental care products is significantly better at removing plaque deposits from fixed appliance patients.

Keywords: orthodontics, dental care, brush, plaque

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Authors: Eman M. Eissa, Hany M. Hasanin, Mahmoud Abd-Elhamid, S. M. Muyeen, T. Fernando, H. H. C. Iu

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Among all available wind energy conversion systems (WECS), the direct driven permanent magnet synchronous generator integrated with power electronic interfaces is becoming popular due to its capability of extracting optimal energy capture, reduced mechanical stresses, no need to external excitation current, meaning less losses, and more compact size. Simple structure, low maintenance cost; and its decoupling control performance is much less sensitive to the parameter variations of the generator. This paper attempts to present a review of the control and optimization strategies of WECS based on permanent magnet synchronous generator (PMSG) and overview the most recent research trends in this field. The main aims of this review include; the generalized overall WECS starting from turbines, generators, and control strategies including converters, maximum power point tracking (MPPT), ending with DC-link control. The optimization methods of the controller parameters necessary to guarantee the operation of the system efficiently and safely, especially when connected to the power grid are also presented.

Keywords: control and optimization techniques, permanent magnet synchronous generator, variable speed wind turbines, wind energy conversion system

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Authors: Mimoza Canga, Alketa Qafmolla, Vergjini Mulo, Irene Malagnino

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Aim: Assessment of oral health in young people aged 18-29 years after the Covid-19 pandemic in Albania. Materials and methods: The present study was conducted at the University of Medicine in Tirana, Albania, from March 2023 to September 2023. This is s cross-sectional study. In our research, 104 students participated, of which 64 were females (61.5%) and 40 were males (38.5%). In the present survey, the participants were divided into four age groups: 18-20, 21-23, 24-26, and 27-29 years old. Majority of the sample (69%) were 18-20 years. Participants were instructed to complete the questionnaire. The study had no dropouts. The current study was conducted in accordance to Helsinki declaration. Statistical analysis was performed using IBM SPSS Statistics Version 23.0, Microsoft Windows Linux, Chicago, IL, USA. Data were analyzed using analysis of variance (ANOVA). P ≤ 0.05 was considered statistically significant. Results: This study reported that 80 (76.9%) of the participants had passed Covid-19, while 24 (23.1%) of them had not passed Covid-19. Based on our data analysis, 70 (67.3%) of the participants had symptoms such as of fever 38°C- 40.5°C and headache. They stated that were treated with Azithromycin 500 mg tablets, Augmentin 625 mg tablets, Vitamin C 1000 mg, Magnesium, and Vitamin D. 40(38.4%) of the participants noticed hypersensitivity in gums (p = 0.004) and sensitive teeth (p = 0.001) after having passed Covid-19 compared to pre-pandemic. Nearly 40 (38.4%) of the participants who passed Covid-19 were treated with painful relievers for the gums and teeth, such as ibuprofen (Advil), used Sensodyne Toothpaste for sensitive teeth and Clove oil. Conclusion: Within the limitations of this study conducted in Albania, can concluded that Covid-19 has a direct impact on oral health.

Keywords: albania, Covid19, cross-sectional study, oral health

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Authors: Karina Nabilla, Dedi Sumantri, Nurul T. Rizal, Siti H. Yavitha

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Background: Composite resin is the most frequently used material for restoring teeth, but still failure cases are seen which leading to microleakage. Microleakage might be attributed to various factors, one of them is bonding agent. Various generations of bonding agents have been introduced to overcome the microleakage. The aim of this study was to evaluate the microleakage of composite restorations using the fifth and seventh bonding agent. Methods: Class I cavities (3X2X2 mm) were prepared on the occlusal surfaces of 32 human upper premolars. Teeth were classified into two groups according to the type of bonding agent used (n =16). Group I: Fifth Generation of Bonding Agent-Adper Single Bond2. Group II: Seventh Generation of Bonding Agent-Single Bond Universal. All cavities were restored with Filtek Z250 XT composite resin, stored in sterile aquades water at 370C for 24 h. The root apices were sealed with sticky wax, and all the surfaces, except for 2 mm from the margins, were coated with nail varnish. The teeth were immersed in a 1% methylene blue dye solution for 24 h, and then rinsed in running water, blot-dried and sectioned longitudinally through the center of restorations from the buccal to palatal surface. The sections were blindly assessed for microleakage of dye penetration by using a stereomicroscope. Dye penetration along margin was measured in µm then calculated into the percentage and classified into scoring system 1 to 3. Data were collected and statistically analyzed by Chi-Square test. Result: There was no significant difference (p > 0,05) between two groups. Conclusion: Fifth generation of bonding agent revealed less leakage compared to the seventh generation even statistically there was no significant difference.

Keywords: composite restoration, fifth generation of bonding agent, microleakage, seventh generation of bonding agent

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Authors: Neeraj Malhotra, Ramya Shenoy

Abstract:

Objective: To assess the effect of clinical parameters (bonding agent, preparation design & storage media) on the strength of reattached anterior tooth fragment. Methodology: This is a systematic review and meta-analysis for articles referred from MEDLINE, PUBMED, and GOOGLE SCHOLAR. The articles on tooth reattachment and clinical factors affecting fracture strength/bond strength/fracture resistance of the reattached tooth fragment in anterior teeth and published in English from 1999 to 2016 were included for final review. Results: Out of 120 shortlisted articles, 28 articles were included for the systematic review and meta-analysis based on 3 clinical parameters i.e. bonding agent, tooth preparation design & storage media. Forest plot & funnel plots were generated based on individual clinical parameter and their effect on strength of reattached anterior tooth fragment. Results based on analysis suggest combination of both conclusive evidence favoring the experimental group as well as in-conclusive evidence for individual parameter. Conclusion: There is limited evidence as there are fewer articles supporting each parameter in human teeth. Bonding agent had showed better outcome in selected studies.

Keywords: bonding agent, bond strength, fracture strength, preparation design, reattachment, storage media

Procedia PDF Downloads 179

Authors: Soheil Heydari, Ailar Hajimohammadi, Nasser Khalili

Abstract:

The application of plastic waste for asphalt modification is a sustainable strategy to deal with the enormous plastic waste generated each year and enhance the properties of asphalt. The modification is either practiced by the dry process or the wet process. In the dry process, plastics are added straight into the asphalt mixture, and in the wet process, they are mixed and digested into bitumen. In this article, the effects of plastic inclusion in asphalt mixture, through the dry process, on the permanent deformation of the asphalt are investigated. The main waste plastics that are usually used in asphalt modification are taken into account, which is linear, low-density polyethylene, low-density polyethylene, high-density polyethylene, and polypropylene. Also, to simulate a plastic waste stream, different grades of each virgin plastic are mixed and used. For instance, four different grades of polypropylene are mixed and used as representative of polypropylene. A precisely designed mixing condition is considered to dry-mix the plastics into the mixture such that the polymer was melted and modified by the later introduced binder. In this mixing process, plastics are first added to the hot aggregates and mixed three times in different time intervals, then bitumen is introduced, and the whole mixture is mixed three times in fifteen minutes intervals. Marshall specimens were manufactured, and dynamic creep tests were conducted to evaluate the effects of modification on the permanent deformation of the asphalt mixture. Dynamic creep is a common repeated loading test conducted at different stress levels and temperatures. Loading cycles are applied to the AC specimen until failure occurs; with the amount of deformation constantly recorded, the cumulative, permanent strain is determined and reported as a function of the number of cycles. The results of this study showed that the dry inclusion of the waste plastics is very effective in enhancing the resistance against permanent deformation of the mixture. However, the mixing process must be precisely engineered to melt the plastics, and a homogenous mixture is achieved.

Keywords: permanent deformation, waste plastics, low-density polyethene, high-density polyethene, polypropylene, linear low-density polyethene, dry process

Procedia PDF Downloads 88

Authors: Seyedmilad Kazemisangdehi, Seyedmehdi Kazemisangdehi

Abstract:

Flux switching permanent magnet machines are considered for wide range of applications because of their outstanding merits including high torque/power densities, high efficiency, simple and robust rotor structure. Therefore, several topologies have been proposed like the PM exited flux switching machine, hybrid excited flux switching type, and so on. Recently, a novel laminated segmented rotor flux switching permanent magnet machine was introduced. It features flux barriers on rotor structure to enhance the performances of machine including torque ripple reduction and also torque and efficiency improvements at the same time. This is while, the design of barriers was not optimized by the authors. Therefore, in this paper three coefficients regarding the position of the barriers are considered for optimization. The effect of each coefficient on the performance of this machine is investigated by finite element method and finally an optimized design of flux barriers based on these three coefficients is proposed from different points of view including electromagnetic torque maximization and cogging torque/torque ripple minimization. At optimum design from maximum developed torque aspect, this machine generates 0.65 Nm torque higher than that of the not-optimized design with an almost 0.4 % improvement in efficiency.

Keywords: finite element analysis, FSPM, laminated segmented rotor flux switching permanent magnet machine, optimization

Procedia PDF Downloads 231

Authors: Justas Dilys

Abstract:

ThispaperaddressestheimplementationandoptimizationofanUnscentedKalmanFilter(UKF) for the Permanent Magnet Synchronous Motor (PMSM) sensorless control using an ARM Cortex- M3 microcontroller. A various optimization levels based on arithmetic calculation reduction was implemented in ARM Cortex-M3 microcontroller. The execution time of UKF estimator was up to 90µs without loss of accuracy. Moreover, simulation studies on the Unscented Kalman filters are carried out using Matlab to explore the usability of the UKF in a sensorless PMSMdrive.

Keywords: unscented kalman filter, ARM, PMSM, implementation

Procedia PDF Downloads 169

Authors: Nicoleta Simona Vedeanu, Rares Stiufiuc, Dana Alina Magdas

Abstract:

A detailed knowledge of the teeth structure is mandatory to understand and explain the defects and the dental pathology, but especially to take a correct decision regarding dental prophylaxis and treatment. The present work is an alternative study to the traditional investigation methods used in dentistry, a study based on the use of modern, sensitive physical methods to investigate human enamel and dentin. For the present study, several teeth collected from patients of different ages were used for structural and dietary investigation. The samples were investigated by Raman spectroscopy for the molecular structure analysis of dentin and enamel, atomic force microscopy (AFM) to view the dental topography at the micrometric size and mass spectrometry for isotopic ratios as a fingerprint of patients’ personal diet. The obtained Raman spectra and their interpretation are in good correlation with the literature and may give medical information by comparing affected dental structures with healthy ones. AFM technique gave us the possibility to study in details the dentin and enamel surface to collect information about dental hardness or dental structural changes. δ¹³C values obtained for the studied samples can be classified in C4 category specific to young people and children diet (sweets, cereals, juices, pastry). The methods used in this attempt furnished important information about dentin and enamel structure and dietary habits and each of the three proposed methods can be extended at a larger level in the study of the teeth structure.

Keywords: AFM, dentine, enamel, Raman spectroscopy

Procedia PDF Downloads 147

Authors: Lata Rathi, N. R. Mrinal

Abstract:

Dental Disfigurement is a major problem for a person who is suffering from Malocclusion. Malocclusion, is a technical name given to crowded, irregular or protruded teeth. In the present investigation the Anxiety and Stress are studied with reference to Dental Disfigurement among Adolescents. The 8 SQ Questionnaire (Cattell,1976)was administered to 50 Male(age range 12-20 years) and 50 Female(age range 12-20 years) patients to investigate anxiety and stress with an equal number of normal’s having no dental disfigurement of teeth. Both the groups, experimental and control were matched on age and sex. It was found that experimental group, i. e. orthodontic patients (M=14.34,s= 4.99) have significantly greater anxiety than their normal counterparts (M=11.8,s= 4.20) F=15.04,p=<.01. The sex differences were not observed. However, with reference to stress it was observed that it was significantly greater in orthodontic patients (M=15.11,s= 4.93 )as compared to normal’s (M=12.83, s=4.87). The gender differences on stress were also observed. The females showed greater stress (M=15.06) as compared to males (M=12.88),F=11.55,p.<1. Overall Malocclusion was found to have significant effect on anxiety and stress.

Keywords: anxiety, malocclusion, orthodontic patients, stress

Procedia PDF Downloads 577