988 research outputs found
Optimum Scheme for Insulation System in HV Generator Based on Electromagnetic Analysis
Electrical insulations are one of the basic parts of electrical machinery in any sizes and characteristics. Focusing on insulating, studies on the operation of industrial-electrical machinery came to the fact that the most important part of a machine is the Stator. This fact reveals the requirement for inspection of the electrical machine insulation along with the electromagnetic tensions. Therefore with respect to insulation system improvement of stator, the HV generator can be optimized. Dielectric parameters such as insulation thickness, spacing, material types, geometry of winding and slot are major design consideration. A very powerful method available to analyze electromagnetic performance is Finite Element Method (FEM) which is used in this paper. The analysis of various stator coil and slot configurations are used to design the better dielectric system to reduce electrical stresses in order to increase the power of generator in the same volume of core. These processes of optimization have been done according the proposed algorithm. In this algorithm the technical constraints have been considered. This paper describes the process used to perform classical design and improvement analysis of stator slotâs insulation with respect to objective function and constraints
Developing a 3D City Digital Twin: Enhancing Walkability through a Green Pedestrian Network (GPN) in the City of Imola, Italy
Predominantly, dense historical cities face insufficient pedestrian-level greenery in the
urban spaces. The lack of greenery impacts the human thermal comfort on the walking paths, which
contributes to a considerable reduction in pedestrian flow rate. This study aims at developing a model
to assess pedestrian-level thermal comfort in city environments and then evaluate the feasibility of
creating a green pedestrian network (GPN). Imola, as a historical city in Italy with a compact urban
pattern, is selected as the case study of this paper. To accomplish this, a three-dimensional digital
twin at city scale is developed for the recognition of real-time shade patterns and for designing a
GPN in this city. The 3D model of the proposed digital twin is developed in the Rhinoceros platform,
and the physiological equivalence temperature (PET) is simulated through EnergyPlus, Honeybee,
and Ladybug components in grasshopper. This study provides the city with a digital twin that is
capable of examining pedestrian-level thermal comfort for designing a GPN based on real-time PET
in the compact urban morphology of Imola. The PET model indicates that during the hottest hour
of the 25th of June, pedestrians in open spaces can experience 3 âC more than on narrow shaded
streets. The results are validated based on in situ datasets that prove the reliability of the developed
digital twin for the GPN. It provides urban planners and policy makers with a precise and useful
methodology for simulating the effects of pedestrian-level urban greenery on human thermal comfort
and also guarantees the functionality of policies in different urban settings
Entropic forces generated by grafted semiflexible polymers
The entropic force exerted by the Brownian fluctuations of a grafted
semiflexible polymer upon a rigid smooth wall are calculated both analytically
and by Monte Carlo simulations. Such forces are thought to play an important
role for several cellular phenomena, in particular, the physics of
actin-polymerization-driven cell motility and movement of bacteria like
Listeria. In the stiff limit, where the persistence length of the polymer is
larger than its contour length, we find that the entropic force shows scaling
behavior. We identify the characteristic length scales and the explicit form of
the scaling functions. In certain asymptotic regimes we give simple analytical
expressions which describe the full results to a very high numerical accuracy.
Depending on the constraints imposed on the transverse fluctuations of the
filament there are characteristic differences in the functional form of the
entropic forces; in a two-dimensional geometry the entropic force exhibits a
marked peak.Comment: 21 pages, 18 figures, minor misprints correcte
Wide parameter search for isolated pulsars using the Hough transform
We use the Hough transform to analyze data from the second science run of the
LIGO interferometers, to look for gravitational waves from isolated pulsars. We
search over the whole sky and over a large range of frequencies and spin-down
parameters. Our search method is based on the Hough transform, which is a
semi-coherent, computationally efficient, and robust pattern recognition
technique. We also present a validation of the search pipeline using hardware
signal injections.Comment: Presented at GWDAW-9 in Annecy, France (Dec. 2004). 11 pages, 5
Figures. To appear in Classical and Quantum Gravit
A comparison of energy and thermal performance of rooftop greenhouses and green roofs in Mediterranean climate: A hygrothermal assessment in WuFi
In urban areas, a considerable proportion of energy demand is allocated to buildings. Since rooftops constitute one-fourth of all urban surfaces, an increasing amount of attention is paid to achieving the most efficient shapes and component designs compatible with every climate and urban context, for rooftops of varying sizes. In this study, three types of rooftop technologies, namely insulated, green roof, and rooftop greenhouse, are evaluated for energy and thermal performance using computer simulations. Water surface exposure, absorption, and intrusion are the three important factors in the calculation of hygrothermal models that impact energy consumption and building envelope performance; however, a few studies are specifically focused on providing realistic results in multi-dimensional hygrothermal models and the assessment of the impact of moisture in roofing solutions. This paper aims at evaluating the performance of three different roofing technologies through a two-dimensional hygrothermal simulation in software WUFI. To accomplish this, a precise localized microclimate model of a complex urban context on the scale of a neighborhood was employed to evaluate the cooling and heating loads of the buildings, the impact of the water content in the green roof on the thermal behavior of the roof surface, and the feasibility of designing a building with nearly zero cooling needs. A two-story building in the city center of Bologna, Italy is modelled. Simulation results have shown that during the cooling period, the performance of the designed rooftop greenhouse is the most effective by 50% reduction in cooling loads. Besides, the impact of moisture in green roofs has been detected as a negative factor for thermal and energy performance of the building in the Mediterranean climate. The results ultimately highlighted the capability of passively-designed rooftop greenhouses to create a building with nearly zero cooling needs
Software Design for Smile Analysis
Introduction: Esthetics and attractiveness of the smile is one of the major demands in contemporary orthodontic treatment. In order to improve a smile design, it is necessary to record âposed smileâ as an intentional, non-pressure, static, natural and reproduciblesmile. The record then should be analyzed to determine its characteristics. In this study,we intended to design and introduce a software to analyze the smile rapidly and precisely in order to produce an attractive smile for the patients.Materials and Methods: For this purpose, a practical study was performed to design multimedia software âSmile Analysisâ which can receive patientsâ photographs and videographs. After giving records to the software, the operator should mark the points and lines which are displayed on the systemâs guide and also define the correct scale for each image. Thirty-three variables are measured by the software and displayed on the report page. Reliability of measurements in both image and video was significantly high(=0.7-1).Results: In order to evaluate intra- operator and inter-operator reliability, five cases were selected randomly. Statistical analysis showed that calculations performed in smile analysis software were both valid and highly reliable (for both video and photo).Conclusion: The results obtained from smile analysis could be used in diagnosis,treatment planning and evaluation of the treatment progress
Comparison of antibiotics and bacteriocins antibacterial activity on Xanthomonas citri subsp.citri
Citrus canker is a citrus disease species created by the bacterium Xanthomonas citri subsp.citri. Many citrus, such as oranges, lime, and grapefruit are affected by the infectious bacteria and stems, leaves and fruits are experiencing loss. In this experiment antibacterial effects of five kinds of antibiotics including ampicillin, kanamycin, chloramphenicol, penicillin, streptomycin, Cronobacteriocin DGH2 and Enterobacteriocin DGH4 were evaluated on 107 strains of Xanthomonas citri subsp.citri. MIC and MBC data for antibiotics and bacteriocins against Xanthomonas strains were performed. According to this project, Xanthomonas strains were comparatively susceptible and resistant to Cronobacteriocin DGH2, Enterobacteriocin DGH4, ampicillin, kanamycin, chloramphenicol, penicillin and streptomycin. NIGEB-183 strain is the most sensitive to these antibiotics and bacteriocins. However, only the NIGEB-242R1 strain is resistant to chloramphenicol. Penicillin has minimum inhibitory effects on Xanthomonas strains. Based on this case study, chloramphenicol is the most antibacterial activity among antibacterial agents and this compound is a good candidate for inhibitory activity. Cronobacteriocin DGH2 has a moderate antibacterial activity against Xanthomonas strains
Parametric Study of Strain Rate Effects on Nanoparticle-Reinforced Polymer Composites
Crashworthiness, energy absorption capacity, and safety are important factors in the design of lightweight vehicles made of fiber-reinforced polymer composite (FRP) components. The relatively recent emergence of the nanotechnology industry has presented a novel means to augment the mechanical properties of various materials. As a result, recent attempts have contemplated the use of nanoparticles to further improve the resiliency of resins, especially when resins are used for mating FRP components. Therefore, a comprehensive understanding of the response of nanoreinforced polymer composites, subjected to various rates of loading, is of paramount importance for developing reliable structures. In this paper, the effects of nanoreinforcement on the mechanical response of a commonly used epoxy resin subjected to four different strain rates, are systematically investigated. The results are then compared to those of the neat resin. To characterize the mechanical properties of the nanocomposite, a combination of the strain rate-dependent mechanical (SRDM) model of Goldberg and his coworkers and Halpin-Tsaiâs micromechanical approach is employed. Subsequently, a parametric study is conducted to ascertain the influences of particle type and their weight percentage. Finally, the numerical results are compared to the experimental data obtained from testing of the neat and the nanoreinforced epoxy resin
Combined training improves the diagnostic measures of sarcopenia and decreases the inflammation in HIVâinfected individuals
Background
HIV-related sarcopenia is an emerging health issue that often remains undiagnosed and can lead to reduced quality of life, independence, and premature death if untreated. This study investigated the effects of a 6 month combined training (resistance plus aerobic exercise) (CT) intervention on diagnostic measures of sarcopenia, including grip strength, appendicular lean mass index (ALMI), and gait speed.
Methods
Forty participants were randomized into either a CT group (n = 20; age = 38.3 ± 4.9 years) or a control group (CON; n = 20; age = 37.9 ± 5.1 years). Participants in the CT group performed three supervised sessions per week for 6 months, consisting of weekly reverse linear periodized resistance training followed by 20 min aerobic training. Participants in the CON group were instructed to continue with their current lifestyle habits. Assessments were completed at baseline and after 6 months. Statistical analyses were performed using a two-way analysis of covariance (ANCOVA) adjusted for sex and preintervention values. Primary outcomes included grip strength, ALMI, and gait speed. Secondary outcomes were changes in levels of pro-inflammatory cytokines (IL-6 and TNF-α), IGF-1, and myostatin. Associations were explored between changes in inflammatory markers (IL-6 and TNF-α), gait speed, and ALMI with grip strength.
Results
A significant increase in ALMI was found for CT compared with CON (0.29 ± 0.13 kg/m2 vs. â0.11 ± 0.14 kg/m2, respectively; P 85%).
Conclusions
Combined training appears to be an effective means to counteract sarcopenia and improve various inflammatory markers and growth hormones in people living with HIV
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