SWOT Analysis using of Modified Fuzzy QFD – A Case Study for Strategy Formulation in Petrokaran Film Factory

AbstractStrategy is a comprehensive program that determines main approaches of the organization and suggests proper ways for allocating resources in order to help the organization to achieve its long term objectives. Environment change, competitiveness and attitude of customers have convinced managers to have a strategic program. In strategic programming SWOT analysis is a useful method that can be used for analyzing strengths and weaknesses within the organization and opportunities and threats from outside of the organization. Although this method is very practical there are some problems in using it. For example there is no tool to determine the importance of factors and this is mostly done by personal preferences. In this paper weight of strengths, weaknesses, opportunities and threats are calculated by Fuzzy Quality Function Deployment and proper strategies for the organization are achieved by HOQ (House of Quality). Hence the customer requirements are important for the strategic planners in this approach the relations between the customer requirements and relations at the top of HOQ are numerically calculated and have impact on internal and external factors of the organization. Because of uncertainty in the decision making factors the calculations are done in a fuzzy environment. At the end this approach is applied in Petrokaran factory as a numerical case study

Impact of modulation instability on distributed optical fiber sensors

Modulation instability (MI) as the main limit to the sensing distance of distributed fiber sensors is thoroughly investigated in this thesis in order to obtain a model for predicting its characteristics and alleviating its effects. Starting from Maxwell's equations in optical fibers, the nonlinear Schrödinger equation (NLSE) describing the propagation of wave envelope in nonlinear dispersive media is derived. As the main tool for analyzing modulation instability, the NLSE is numerically evaluated using the split-step Fourier method and its analytical closed-form solutions such as solitons are utilized to validate the numerical algorithms. As the direct consequence of the NLSE, self-phase modulation is utilized to measure the nonlinear coefficient of optical fibers via a self-aligned interferometer. The modulation instability gain is obtained by applying a linear stability analysis to the NLSE assuming a white background noise as the seeding for the nonlinear interaction. The MI gain spectrum is expressed by hyperbolic functions for lossless fibers and by Bessel functions with complex orders for fibers with attenuation. An approximate gain spectrum is presented for lossy fibers based on the gain in lossless optical fibers. The accuracy of the analytical results and approximate formulas is evaluated by performing Monte Carlo simulations on the NLSE. The impact of background noise on the onset and evolution of modulation instability is analytically investigated and experimentally demonstrated. Power depletion due to the nonlinear process of modulation instability is modeled by integrating its gain spectrum using Laplace's method. Based on that, a critical power for MI is proposed by introducing the notion of depletion ratio. The model is verified by numerical simulation and experimental measurement. An optimal input power for distributed fiber sensors is proposed to maximize the output optical power and thus, the far end signal-to-noise ratio. Furthermore, the recurrence phenomenon of Fermi-Pasta-Ulam is experimentally observed and numerically simulated, validating the utilized numerical techniques. A standard Brillouin optical time-domain analyser serves as the experimental test bench for the proposed model. As the physical phenomenon behind the experiment, stimulated Brillouin scattering is described based on a pump-probe interaction mechanism through an acoustic wave. A 25 km single-mode fiber is employed as a nonlinear medium with anomalous dispersion at the pump wavelength 1550 nm. The evolution of pump power propagating along the fiber is mapped using the Brillouin interaction with the probe lightwave. The measured longitudinal power traces are processed to extract the impact of MI on the pump power. It is experimentally demonstrated that distributed fiber sensors with orthogonally-polarized pumps suffer less from modulation instability. As the scalar modulation instability of each pump reduces, vector modulation instability occurs because of interaction between the pumps; however, the overall performance improves. A version of the coupled nonlinear Schrödinger equations known as the Manakov system is shown to describe the behavior of two-pump distributed fiber sensors employing optical fibers with random birefringence. The excellent agreement between the experimental and numerical results indicates that the performance limit of two-pump distributed fiber sensors is determined by polarization modulation instability

Analytical model and experimental verification of the critical power for modulation instability in optical fibers

Modulation instability is thoroughly investigated and a simple analytical model for its power critically modifying the wave properties in terms of system parameters is derived and experimentally validated. The differences on the modulation instability gain spectrum in lossless and lossy optical fibers are analyzed based on theoretical models and numerical simulations. In particular the impact of background noise on the behavior of modulation instability is studied analytically and verified by measurements and simulations. The proposed analytical model is experimentally validated by monitoring the wave propagation along an optical fiber using a Brillouin optical time-domain analyzer. This way, the evolution of the optical signal traveling through optical fibers, especially, the pump depletion and the recurrence phenomenon are investigated

Modelling the depletion length induced by modulation instability in distributed optical fibre sensors

An analytical model for the depletion length of modulation instability in single-mode optical fibres is proposed. The model gives the possibility to determine the maximum sensing distance that distributed optical fibre sensors can reach before being limited by the pump depletion induced by modulation instability. The important role of the noise level in the evolution of both modulation instability and the respective power depletion is clarified. The model gives a closed form expression helpful for a predictive design and is validated comparing the analytical results obtained by the model with measurements in a 25 km long Brillouin fibre sensor

Analytical expression and experimental validation of the Brillouin gain spectral broadening at any sensing spatial resolution

A novel and simple analytical expression to describe the Brillouin gain spectral broadening as a function of the spatial resolution in time-domain Brillouin distributed fiber sensors is deduced. The proposed model is experimentally validated using a pump-probe Brillouin sensing setup and also compared with numerical and approximate results. In addition, a compact mathematical form is presented for the peak gain reduction resulting from incomplete acoustic-wave activation in Brillouin sensors with short spatial resolution. Both mathematical expressions can be used together to quantitatively predict the impact of the spatial resolution on the signal-to-noise ratio and frequency uncertainty of the sensor

Mitigating modulation instability in Brillouin distributed fibre sensors

A thorough study of the generation of modulation instability (MI) in distributed Brillouin fibre sensors is presented. ASE noise co-propagating with the pump pulses within the MI gain spectrum has been identified to be an important factor seeding modulation instability and reducing its power threshold. The paper describes how optical narrowband filtering reduces the pump depletion resulting from MI, allowing pump pulses to propagate through longer distances in standard optical single-mode fibres

Mitigation of modulation instability in Brillouin distributed fiber sensors by using orthogonal polarization pulses

A technique based on the use of orthogonally-polarized pulses is proposed to mitigate the detrimental impact of modulation instability on Brillouin distributed fiber sensors. While the theoretical underpinnings of the method are described by introducing a detailed model for the vector modulation instability, the technique is experimentally validated in a 25-km sensing link. Numerical and experimental results demonstrate that the use of orthogonally-polarized pulses not only mitigates the impact of modulation instability, but also the four-wave mixing occurring in systems using pumps with parallel polarization; thus, providing an important sensing range enhancement with a reduced pump depletion.J. Urricelqui, M. Sagues and A. Loayssa acknowledge the support from the Spanish Ministerio de Economia y Competitividad through the project TEC2013-47264-C2-2-R, FEDER funds and Universidad Pública de Navarra

Optical Nyquist-pulse generation with a power difference to the ideal sinc-shape sequence of < 1%

Sinc-shaped Nyquist-pulses possess a rectangular spectrum. Thus, a sinc-pulse transmission minimizes the carrier spacing down to the baud rate, and therefore, substantially increases the transmissible data rates. These perspectives have led to a strong research activity in the field of Nyquist pulse transmission. However, all methods of Nyquist pulse generation shown up to now are rather complex, costly and none leads to ideal sinc-shaped Nyquist pulses. Thus, it has not been clear yet if Nyquist-pulse transmission can be incorporated in optical networks in an energy and cost-effective way. Here we present a method for the generation of almost ideal sinc-shaped Nyquist pulses based on a flat and phase-locked frequency comb. The pulses can be generated with conventional modulators without any sophisticated electronics or other costly equipment. In our proof-of-concept experiment we generate sinc-shaped Nyquist-pulse sequences which show a power difference lower than 1% compared to an ideal sequence. Generated sinc pulses have a full width at half maximum (FWHM) duration of 9.8 ps, an out-of-band suppression of more than 27 dB, a signal-to-noise ratio of more than 40 dB and a jitter of 82 fs, equivalent to 0.82% of the FWHM. The pulse width and repetition rate can be changed simply by tuning the comb parameters

Performance limit of two-pump Brillouin fiber sensors obtained by Manakov modulation instability

The Manakov modulation instability is shown to determine the performance limit of long-distance Brillouin fiber sensors utilizing orthogonally-polarized pumps. Numerical simulations of the Manakov equation are supported by the experimental measurement of a 25-km Brillouin fiber sensor to verify the model. The study reveals that the use of orthogonally-polarized pulses decreases the pump depletion due to modulation instability leading to an enhancement of the sensing distance