In this paper, we propose a modified design of a hexagonal circular photonic crystal fiber (HC-PCF) which obtains a large negative dispersion and ultrahigh birefringence simultaneously. The optical properties of the proposed HC-PCF were investigated using the finite element method (FEM) incorporated with a circular perfectly matched layer at the boundary. The simulation results showed large negative dispersion of −1044 ps/nm.km and ultrahigh birefringence of 4.321 × 10−2 at the operating wavelength of 1550 nm for the optimum geometrical parameters. Our proposed HC-PCF exhibited the desirable optical properties without non-circular air holes in the core and cladding region which facilitates the fabrication process. The large negative dispersion of the proposed microstructure over the wide spectral range, i.e., 1350 nm to 1600 nm, and high birefringence make it a suitable candidate for high-speed optical broadband communication and different sensing applications.

Churners have always been a big issue for any service providing company. Churning increases cost of the company as well as decreases the rate of profit. Generally, customer attrition can be identified when they initiate the process of service termination. At the same time, the individuals and the institutions that provide the data residing on the government databasesas well as the agencies who sponsor the collection of such information-are becoming increasingly aware that extend analytical capabilities also furnish tools that threaten the confidentiality of data records. However, using predictive analysis using customers past service usage, service performance, spending and other behavior patterns, the likelihood of whether a customer wants to terminate service can be determined. In this paper, the authors address the issue of churn analysis considering a scenario in which a company owning confidential databases wish to run a churn analysis technique on the union of their databases, without revealing any unnecessary information. The aim of the paper is to predict whether a customer will churn in the near future or not based on the predictive analysis using billing data of a telecom company.

The IEEE 802.11e Enhanced Distributed Channel Access (EDCA) is the distributed channel access mechanism introduced by an amendment to the original IEEE 802.11 standard. EDCA provides a class-based differentiated Quality of Service (QoS) to IEEE 802.11 WLANs. This paper presents a simulation study of the EDCA mechanism, considering a single Access Point (AP) based WLAN system.We used in our simulation study, the International Telecommunication Union (ITU) indoor propagation model considering the indoor or semi-indoor deployment scenarios of the WLAN systems in most real life cases. Simulation experiments show that a node accessing highest priority traffic through an AP from a high distance at high data rate not only suffers performance drops itself but also severely bottlenecks the performance of other client nodes, accessing traffics with comparatively lower priority even if those nodes are at close proximity from the AP.

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In this study, an ultra-wide range plasmonic refractive index sensor based on dual core photonic crystal fiber is suggested and analyzed numerically. The proposed design achieves fabrication feasibility by employing external sensing mechanism in which silver is deposited onto the flat outer surface of the fiber as plasmonic material. A thin layer of titanium oxide (TiO2) is considered on top of the silver layer for preventing its oxidation problem. The sensor attains identification of a vast array of analytes consisting a wide range of refractive indices of 1.10 – 1.45. It achieves a maximum spectral sensitivity of 24300 nm/RIU along with its corresponding resolution of 4.12 × 10−6 RIU. The maximum figure of merit of the sensor is 120 RIU−1. The sensor also supports amplitude interrogation approach and exhibits a maximum amplitude sensitivity of 172 RIU−1. The impact of the design parameters such as radius of air holes, polishing distance, thickness of silver and titanium oxide layers are investigated thoroughly. An ultra-wide detection range with high sensitivity, fabrication feasibility, and easy application make the sensor a potential candidate for detection of a wide array of bio-originated materials, chemicals, and other analytes.