Design and simulation of 1.28 Tbps dense wavelength division multiplex system suitable for long haul backbone

Wavelength division multiplex (WDM) system with on / off keying (OOK) modulation and direct detection (DD) is generally simple to implement, less expensive and energy efficient. The determination of the possible design capacity limit, in terms of the bit rate-distance product in WDM-OOK-DD systems is therefore crucial, considering transmitter / receiver simplicity, as well as energy and cost efficiency. A 32-channel wavelength division multiplex system is designed and simulated over 1000 km fiber length using Optsim commercial simulation software. The standard channel spacing of 0.4 nm was used in the C-band range from 1.5436-1.556 nm. Each channel used the simple non return to zero - on / off keying (NRZ-OOK) modulation format to modulate a continuous wave (CW) laser source at 40 Gbps using an external modulator, while the receiver uses a DD scheme. It is proposed that the design will be suitable for long haul mobile backbone in a national network, since up to 1.28 Tbps data rates can be transmitted over 1000 km. A bit rate-length product of 1.28 Pbps.km was obtained as the optimum capacity limit in 32 channel dispersion managed WDM-OOK-DD system.Comment: Accepted for publication in Journal of Optical Communications - De Gruyte

Design and Simulation of 1.28 Tbps Dense Wavelength Division Multiplex System Suitable for Long Haul Backbone

Wavelength division multiplex (WDM) system with on/off keying (OOK) modulation and direct detection (DD) is generally simple to implement, less expensive and energy efficient. The determination of the possible design capacity limit, in terms of the bit rate – distance product in WDM – OOK –DD systems is therefore crucial, considering transmitter/receiver simplicity, as well as energy and cost efficiency. A 32-channel WDM system is designed and simulated over 1000 km fiber length using Optsim commercial simulation software. The standard channel spacing of 0.4 nm was used in the C–band range from 1.5436 to 1.556 nm. Each channel used the simple non return to zero – on/off keying (NRZ – OOK) modulation format to modulate a continuous wave (CW) laser source at 40 Gbps using an external modulator, while the receiver uses a DD scheme. It is proposed that the design will be suitable for long haul mobile backbone in a national network, since up to 1.28 Tbps data rates can be transmitted over 1000 km. A bit rate length product of 1.28 Pbps.km was obtained as the optimum capacity limit in 32 channel dispersion managed WDM – OOK – DD system

Natural Genetic Variation in Selected Populations of Arabidopsis thaliana Is Associated with Ionomic Differences

Controlling elemental composition is critical for plant growth and development as well as the nutrition of humans who utilize plants for food. Uncovering the genetic architecture underlying mineral ion homeostasis in plants is a critical first step towards understanding the biochemical networks that regulate a plant's elemental composition (ionome). Natural accessions of Arabidopsis thaliana provide a rich source of genetic diversity that leads to phenotypic differences. We analyzed the concentrations of 17 different elements in 12 A. thaliana accessions and three recombinant inbred line (RIL) populations grown in several different environments using high-throughput inductively coupled plasma- mass spectroscopy (ICP-MS). Significant differences were detected between the accessions for most elements and we identified over a hundred QTLs for elemental accumulation in the RIL populations. Altering the environment the plants were grown in had a strong effect on the correlations between different elements and the QTLs controlling elemental accumulation. All ionomic data presented is publicly available at www.ionomicshub.org

Cocoa Pod Ash as Bio-Based Catalyst for Biodiesel Production from Waste Chicken Fat

The growing interest in using sustainable raw materials coupled with the need to reduce the over- dependence on non-renewable petroleum resources has made agricultural residues attractive raw material for biofuel production. The potential utilization of cocoa pod ash (CPA) as a bio-based catalyst for the production of biodiesel from waste chicken fat was investigated. Bio-based catalyst was obtained from cocoa pods by ashing method. The catalyst was subjected to scanning electron microscope (SEM) analysis. The experimental design was based on a five level, two factor central composite design. CPA was used in the preparation of biodiesel from waste chicken fat (WCF) using a two-step esterification-transesterification process. The highest biodiesel yield of 75.4% was obtained at 3 wt % catalyst concentration and 2 hours reaction time. The results obtained by GCMS analysis confirmed the fatty acid methyl ester production. The biodiesel properties such as density, viscosity, saponification value, iodine value, acid value and colour suggested CPA as a potential bio-based catalyst for transesterification of oil obtained from waste chicken fat

Forensic analysis of android-based telegram messenger for cybercrime investigation using the NIST framework

This paper presents a forensic analysis of Telegram messenger (running on Android) which is a popular instant messaging application that offers secure one-to-one, one-to-many and many-to-many communication services reportedly used for various criminal activities. Various works have been reported on forensic analysis of Instant Messaging (IM) applications, but there is the need to follow investigative standards treating all cases as if they would end up in court. Hence, this study used the National Institute of Standards Technology (NIST) methodology which has four (4) forensic stages namely, collection, examination, analysis and reporting. The results from this research are a comparison of evidence obtained in form of conversation database, direct and group messages, images and documents sent and received between a rooted smart phone and a non-rooted smart phone. The output of this research will be beneficial to forensic investigators and researchers in identifying and recovering digital evidence from telegram messenger on android devices which can form a reference in proceedings to combat cybercrime

Securing Logins in Electronic Examination Systems for Tertiary Institutions Using Quick Response Code (QR) Technology and Multiple Hashing Algorithms

This work is aimed at adding an extra layer of security to the login process of an electronic examination system as security has been identified as one of the critical success factors in the management of such exams. It proposes to secure the login process of an e-exam system through authentication and encryption to control access and avoid impersonation. A model of the e-exam system with Quick Response (QR) code generation capability was designed where a student’s matriculation number is accepted as input which is then converted into a two-dimensional bar code using a QR generator. Outputs from the QR code generator are then secured by encryption using MD5 and SHA-224 encryption algorithms. MD5 algorithm produces a 32-bit hash value which is further encrypted using SHA-224 that produces a resulting 56-bit hash value that is then saved in the password column of the user table in the database. This research resulted in a secure and web-based electronic examination authentication system implemented and tested on a client-server architecture. Performance evaluation of the developed system revealed that it is fast and effective, capable of  authenticating students in an average of 0.624 seconds when the smartphone flashlight is off, and 0.318 seconds with flashlight turned on and consequently, resistant to brute force attacks. This paper fulfils an identified need to develop an electronic exam system that not only secures the question bank but equally ensures the security of the login process as well as the login details using a combination of two security techniques