جستجوی مقالات مرتبط با کلیدواژه « فیبر نوری » در نشریات گروه « فنی و مهندسی »

In this research, creative techniques have been applied on the surface of polymer optical fiberto observ new optical effects in the production of luminous textiles and their further application in designing luminous clothing. Accordingly, optical fibers of three different thicknesses (0.25, 0.5, and 0.75 mm) were subjected to secondary operations using techniques such as knotting, pulling, grinding the surface with sandpaper, melting, and creating scratches with a cutter, and were exposed to LED to evaluate their luminescence. The result showed that the light emitted from fibers with greater thickness shined more than the similar samples in fibers with less thickness. Additionally, a thicker fiber has been proven to be less flexible than a thinner fiber. Thinner plastic fibers revealed faster melting and weremore fragile and more sensitive to heat. In the knotting and melting methods, the obtained light was appeared in the form of a three-dimensional spotlight. In the melting method, the resulting light was appeared brighter than other samples due to the formation of a spherical shape in the fiber tip. On the other hand, the light emitted from the samples exposed to sanding and pulling scatter appeareduniformly due to the fiber transparency and linear processing. The conducted research declaredthe high potential of optical fibers for the production of luminous textiles with unique design capabilities and their high efficiency in the fashion and clothing industry.

The use of broadband pulses in structures based on phase shift antenna arrays is difficult due to the Luchi beam phenomenon. Therefore, as an alternative method, structures based on the real time delay of photonic microwave technology are used, which increases the usable bandwidth. However, the use of conventional photonic microwave technology and the conditions related to its modulator, itself causes the limitation of bandwidth and pulse level. In this article, the performance of a real time delay structure has been improved by using a special type of optical fibers under the physical phenomenon of modulation instability, which increases the pulse power level and bandwidth. In fact, the performance improvement of a modulator with a single laser (carrier signal) was extended to the frequency comb mode.

In recent decades, the pavement health monitoring issue has attracted the attention of many researchers and has led to new advances and technologies. In this study, while examining the monitoring concept, the existing methods for monitoring the structural health of pavements have been categorized. To date, two general monitoring approaches from surface and inside the pavement have been used to assess their structural health. The new monitoring method using embedded equipment inside the pavement seeks to provide solutions aimed at continuous monitoring of structural health. These solutions rely on pavement instrumentation. This means that sensors are embedded inside the road during the road construction process. Utilizing monitoring methods inside the pavement can bring many technical and economic benefits to road networks. Compared to the pavement monitoring method from its surface, it can facilitate monitoring all pavement layers separately, continuously and remotely without interfering with traffic flow. This approach is in line with the realization of smart roads and, unlike most of the old methods, it is a non-destructive method. For this purpose, in this study, a review of recent researches on monitoring methods inside the pavement has been conducted. To this end, electromagnetic, fiber optic and wireless monitoring sensors have been evaluated. Finally, some suggestions have been proposed in order to utilize these monitoring techniques for Iranian road infrastructures.

Today, fiber-optic due to its higher bandwidth and cost effective in compare with other similar technologies is one of the most important tools of data transfer. In this paper, an integrated mathematical model is presented for the three-level network of fiber-optic by considering the backbone network and local access networks simultaneously. Used topologies in its levels are respectively ring, star, and star. The purpose of this model is determine the location of the central hubs and concentrators, communication of central hubs and also assign each user to one of the concentrators such that the costs of the fiber link and installation the concentrators get minimize as well as providing the bandwidth required per user. Due to NP-hardness of this problem, small size of proposed model validated by GAMS software, then the model is solved by two meta-heuristic methods of DE and GA in large-sizes and the results of the two algorithms have been compared in terms of time and objective function value. The result shows the required time to achieve optimum solution in the DE is less than GA and also DE has better performance in small and medium-sized of problem but for the large size of problem the GA algorithm is better than DE

In this paper, a new simple refractive index (RI) sensor based on plasmonic nanostructure D-shape fiber is proposed. In this structure, surface plasmon resonances are sensitive to the surrounding medium on the flat side of the D-shape fiber. In the proposed sensor, the sensitivity of 1025nm/RIU is obtained. The significance of the proposed sensor lies with its compact in size, robust and simple in structure, and high value of sensitivity. In addition, an important property of the designed structure is that the excitation of surface plasmon resonances in this type of fiber is simple. The proposed structure can be applicable to the identification of different bio-molecules or chemical materials.

One of the recently considered applications of fiber optic, in their usage in building lighting systems. In this research, in order to reduce energy consumption, by transmission of sun light from the roof to the desired place (i.e. an office), the required standard luminance is produced. The main aims of this research are :1. Reduction of energy consumption.
2. Making the place compatible with the human favorable mental conditions and environment.
3. Preparing the basics of mass production of the system and economical benefits for the university
In this research besides concentrating the sun light to magnify its density, some investigations are made for light transmission by fiber optics, because, no mathematical model was found for this per pose, practical tests are made in addition to statistical analysis.
Using different lenses and fiber optics and a position control system (which specially designed for this research), many experiences were made and iluminances were measured by a lux meter. After that by SPSS V.17 software, the results were analyzed. Finally the best Lenz and fiber were selected and a straight forward method was presented for designing a typical office in such manner.

One of the recently considered applications of fiber optic, in their usage in building lighting systems. In this research, in order to reduce energy consumption, by transmission of sun light from the roof to the desired place (i.e. an office), the required standard luminance is produced. The main aims of this research are :1. Reduction of energy consumption.
2. Making the place compatible with the human favorable mental conditions and environment.
3. Preparing the basics of mass production of the system and economical benefits for the university
In this research besides concentrating the sun light to magnify its density, some investigations are made for light transmission by fiber optics, because, no mathematical model was found for this per pose, practical tests are made in addition to statistical analysis.
Using different lenses and fiber optics and a position control system (which specially designed for this research), many experiences were made and iluminances were measured by a lux meter. After that by SPSS V.17 software, the results were analyzed. Finally the best Lenz and fiber were selected and a straight forward method was presented for designing a typical office in such manner .