Monir Morshed

DESIGN AND CHARACTERIZATION OF PHOTONIC CRYSTAL FIBER FOR SENSING APPLICATIONS

Purpose: this study aimed to analyze the epidemiological aspects and evaluate the impact of late diagnosis on prognosis of gastrointestinal surgical emergencies at the National Hospital of Zinder (Niger). Patients and method: this is a prospective study from 1 January to 31 December 2013. All patients underwent surgery for digestive emergency were included. Results: We collected 302 patients. Emergencies digestive surgery accounted for 22% of 1358 cases of surgical emergencies recorded over the period of the study period. The sex ratio is 3/1 in favor of men. The average age of patients was 23 years. Digestive surgical emergencies affect more children (45%) and young adults (43%). The majority (70%) of our patients did not attend school and 49% were from rural areas. The diagnosis delay rule, 171 patients (57%) arrived to emergency department more than 48 hours after onset of symptoms. Abdominal pain with or without other signs was the main reason for consultation (92% of patients). 182 patients had a poor general status. The etiologies were dominated by peritonitis (52%) followed by intestinal obstruction (28%), and abdominal trauma with 10% of cases. The parietal suppuration isolated or associated with other morbidities was the main postoperative (28%). The average length of hospital stay was 9 days. 36 patients (12%) had died. Almost half of the deaths (47%) occurred within the first 48 hours of admission. The delay of admission and the surgical management was statistically significant effect on the prognosis (P<0.006, p< 0.0001). Conclusion: The prognosis of gastrointestinal surgical emergencies is highly correlated with the speed of diagnosis leading to appropriate treatment as soon as possible. This promptness is the only guarantee of a decline in the high morbidity and mortality which is often linked to dysfunction of our hospitals and/or accessibility problems faced by patients.

Proposal of simple gas sensor based on micro structure optical fiber

This paper presents a simple structure of photonic crystal fiber (PCF) based gas sensors. Gas sensors can be used in gas production facilities for safe measurement. The index guiding properties of two rings circular PCF have been analysed for different wavelength with the variation of the diameters of air holes in core and cladding. Finite-element method has been applied for numerical analysis. At the wavelength λ=1.66μm obtained maximum sensitivity is 13.94% and at the same time the confinement loss of the fiber is 2.74×10-4 dB/m. The proposed structure is more flexible for its high sensitivity, low confinement loss and simple structure compare to early proposed high sensitivity chemical sensor PCFs with a hollow high index ring defect at the centre.

Application of microarray-core based modified photonic crystal fiber in chemical sensing

This study presents a simple type of modified PCF (M-PCF) as a chemical sensor where both core and cladding are micro-structured. Different guiding properties of proposed M-PCF have been investigated for a wide range of wavelength using full vectorial finite element method (FEM). By varying pitch and hole diameter both of inner and outer layers, the relative sensitivity, refractive index and confinement loss are numerically examined and compared. At the wavelength 1.33μm it is observed that the relative sensitivity is improved 1.45 times and confinement loss is also reduced than prior work. Fabrication process and cost will be low of proposed M-PCF because of its structural simplicity.

Performance analysis of low pass FIR filters design using Kaiser, Gaussian and Tukey window function methods

Digital filter plays an important role in the advanced era of communication system. Digital filters basically provide high attenuation to the unwanted ones and offer very low or ideally zero attenuation to desired signal components when its impulse response is adjusted as per requirement. But the design of a digital filter satisfying all the required conditions is a challenging task. In this paper, design techniques of low pass FIR filters using Tukey window, Kaiser Window, and Gaussian window methods are presented. The magnitude and phase responses are demonstrated in the simulation section for the different design techniques of digital low pass FIR filters. From the simulation results, it is observed that for a longer length the FIR filter has a sharper cut-off FIR filter and a narrow transition band.

Active noise control using filtered-xLMS and feedback ANC filter algorithms

Active noise control (ANC) is one of the most popular applications for adaptive filters. In the emerging application area of adaptive signal processing is active noise control. The basic idea behind the active control of acoustic noise is to inject a secondary sound (anti-noise) into an environment so as to cancel the primary sound using destructive interference. So, ANC is a method of reducing the unwanted noise by actively generating an anti-sound, cancelling out the noise. To achieve this, in this paper, we describe a well-known filtered-X Least Mean Square (filtered-x LMS) and feedback active noise control algorithms which provide a new structure for improving noise reduction. Finally, simulation results have shown the effectiveness of the proposed algorithm.

Ultra-flattened negative dispersion for residual dispersion compensation using soft glass equiangular spiral photonic crystal fiber

Abstract We present a numerical investigation of an equiangular spiral photonic crystal fibre (ES-PCF) in soft glass for negative flattened dispersion and ultra-high birefringence. An accurate numerical approach based on finite element method is used for the simulation of the proposed structure. It is demonstrated that it is possible to obtain average negative dispersion of –526.99 ps/nm/km over 1.05–1.70 μm wavelength range with dispersion variation of 3.7 ps/nm/km. The proposed ES-PCF also offers high birefringence of 0.0226 at the excitation wavelength of 1.55 μm. The results here show that the idea of using the proposed fibre can be potential means of effectively directing for residual dispersion compensation, fibre sensor design, long distance data transmission system and so forth.

High sensitive PCF based chemical sensor for ethanol detection

In this paper, a high sensitive photonic crystal fiber structure has been presented for ethanol sensing. Optical properties of the guided mode have been analyzed using full vectorial finite element method. We have investigated the sensing properties varying different geometrical properties of the proposed structure. We have optimized the design parameters of the proposed PCF which are responsible for high sensitivity. The simulation results show that the sensitivity and the confinement loss of the proposed photonic crystal fiber are 34% and 1.2×10-4 dB/m respectively at the wavelength of 1.33μm.