Soil NPK Variability Mapping for Harumanis Mango Grown in Greenhouse at Perlis, Malaysia

Soil is essential for plant growth. The soil provides support for plant, medium for root growth, and most importantly it offers nutrients for plant uptake. The nutrients variability in soil is vary depending on several factors such as soil type, soil microbes, and soil pH. Therefore, nutrients available in the soil is important to be mapped to investigate the state of nutrient present. In this study, the available content of Nitrogen (N), Phosphorus (P) and Potassium (K) were determined for a high-density planting systems of Harumanis mango plants grown in the greenhouse. Thirty-two soil samples were collected from a greenhouse for analysis of NPK content in top soil. The soil was analyzed using the Kjeldahl method, UV Spectrophotometer and Atomic Absorption Spectroscopy (AAS) for N, P, and K content respectively. These amount of macronutrients were then mapped with respective georeferenced location to produce NPK nutrients maps using standard classification in ArcGIS software. Results have indicated that N, P, and K were ranged between 0.06 - 0.12% (very low), 4 - 648 ppm (low-very high) and 0.02 -1.37 cmol/kg (low-high) accordingly. Overall, it can be concluded, soil in selected greenhouse is poor in N, high in P and moderate in K content. Hence, it is suggested more N and adequate amount of K fertilizer should be supplied to increase the plant's productivity.  The produced maps give a new perspective in a farming management concept in term of variable rate fertilizer application for Harumanis mango plants grown in the greenhouse

Low threshold L-band mode-locked ultrafast fiber laser assisted by microfiber-based single wall carbon nanotube saturable absorber

We demonstrate a passively mode-locked erbium-doped fiber laser in L-band wavelength region with low mode-locking threshold employing a 1425 nm pump wavelength. The mode-locking regime is generated by microfiber-based saturable absorber using carbon nanotube-polymer composite in a ring cavity. This carbon nanotube saturable absorber shows saturation intensity of 9 MW/cm². In this work, mode-locking laser threshold is observed at 36.4 mW pump power. At the maximum pump power of 107.6 mW, we obtain pulse duration at full-width half-maximum point of 490 fs and time bandwidth product of 0.33, which corresponds to 3-dB spectral bandwidth of 5.8 nm. The pulse repetition rate remains constant throughout the experiment at 5.8 MHz due to fixed cavity length of 35.5 m. Average output power and pulse energy of 10.8 mW and 1.92 nJ are attained respectively through a 30% laser output extracted from the mode-locked cavity. This work highlights the feasibility of attaining a low threshold mode-locked laser source to be employed as seed laser in L-band wavelength region

Ultrashort pulse laser generation in ring-type EDFL using carbon-nanotube saturable absorber

This study investigates the capability of an ultrashort pulse laser in a ring cavity of erbium-doped fiber laser (EDFL). Generation of pulses was performed by inserting a carbon-nanotube saturable absorber in this EDFL. Mode-locked laser was achieved with an average power of 20mW and a peak power of 3.37kW. Pulse duration laser of 9S0fs with repetition rate of 6.24MHz was obtained at 3dB bandwidth of 3.6Snm. Higher power with better pulse duration can be achieved by optimizing the cavity length

Fabrication of Tm2O3/Al2O3-silica preform by improved MCVD-chelate delivery system

The fabrication of Tm/Al-doped silica preforms by an improved MCVD method with metal chelate precursors is discussed. Two fabrication techniques are employed, namely; simultaneous soot-dopant deposition (or standard MCVD) and stepwise soot-dopant deposition. The preforms are characterized by refractive index profiler and EPMA. The results show that the stepwise soot-dopant technique has a higher incorporation of Al2O3 and Tm2O3 as compared to the simultaneous soot-dopant method. This is due to the drawbacks of our chelate delivery system such as the temperature gradient and flow design. For the stepwise technique, the measured index difference of the preform is 0.006 with 0.8 wt% (maximum) Tm incorporated in the core

Multiple soaking with different solution concentration in doped silica preform fabrication using modified chemical vapor deposition and solution doping

Incorporation of alumina (Al2O3) into a silica matrix by modified chemical vapor deposition and a solution doping technique is investigated in this study. Multiple soaking cycles were used to increase the aluminum content in the core layer. The effect of alumina retention in silica matrix soot is focused by multiple cycles of soaking with different solution concentrations, while the effect of the adsorption mechanism is fixed by maintaining the soot deposition process (such as temperature [1,800°C], precursor, total gas flow, and soaking time). The deposited soot is examined for porosity characteristics and effective surface area by a gas adsorption technique with Brunauer-Emett-Teller surface area analysis and the surface and cross-section morphology using scanning electron microscopy. Three different concentrations are used in this work (0.3, 0.7, and 1.2 M) with multiple cycles of soaking. Sintering and the collapsing process is controlled for each preform. The result shows that the alumina content is increased substantially as the number of soaking processes is increased, which may be due to the retention effect as only a small amount of adsorption process takes place as indicated by the slight decrease in the surface area of soot. The collapsed preforms are analyzed using a preform analyzer. Energy dispersive x-ray spectrometry is used to check aluminum content and distribution into the core layer

AALLA: Attack-Aware Logical Link Assignment Cost-Minimization Model for Protecting Software-Defined Networks against DDoS Attacks

Software-Defined Networking (SDN), which is used in Industrial Internet of Things, uses a controller as its “network brain” located at the control plane. This uniquely distinguishes it from the traditional networking paradigms because it provides a global view of the entire network. In SDN, the controller can become a single point of failure, which may cause the whole network service to be compromised. Also, data packet transmission between controllers and switches could be impaired by natural disasters, causing hardware malfunctioning or Distributed Denial of Service (DDoS) attacks. Thus, SDN controllers are vulnerable to both hardware and software failures. To overcome this single point of failure in SDN, this paper proposes an attack-aware logical link assignment (AALLA) mathematical model with the ultimate aim of restoring the SDN network by using logical link assignment from switches to the cluster (backup) controllers. We formulate the AALLA model in integer linear programming (ILP), which restores the disrupted SDN network availability by assigning the logical links to the cluster (backup) controllers. More precisely, given a set of switches that are managed by the controller(s), this model simultaneously determines the optimal cost for controllers, links, and switches

Aluminum doped silica preform fabrication using MCVD and solution doping technique: effects of various aluminum solution concentrations

This work is described for solution doping in Modified Chemical Vapor Deposition (MCVD) used for silica optical fiber fabrication. This paper will concentrate on aluminum solution doping and the effect of different solution concentrations. The effect of three different concentrations of aluminum (O.3M, O.7M and 1.2M) with the soot undergo heat treatment are studied while the other parameters of MCVD and solution doping are fixed such as deposition temperature, SiCI4 flow, and soaking time. The refractive index profile (RIP) of each doped preform is measured using preform analyzer to investigate aluminum distribution in the core region. Further investigation about Al distribution across the core sintered layer is also examined by EDX techniques

Design and performance of an S-band thulium doped modified silica fiber amplifier

A new design of an S-band Thulium-doped modified Silica fiber co-doped with aluminum is presented. The design goal is high gain and low noise figure in the wavelength range of 1450 - 1520 nm. The optimization considers design parameters such as the cut-off wavelength, dopant concentration, waveguide structure, index profile and numerical aperture. These design parameters are optimized to achieve long fluorescence lifetime, high overlap factor and selected mode excitation. The amplifier performance is theoretically modelled and simulated considering the proposed design optimization. We show that the amplifier can achieve a gain of 16 dB and 3dB noise figure

On the fabrication of aluminum doped silica preform using MCVD and solution doping technique

This paper provides detailed discussions on the fabrication of aluminum doped silica preform using solution doping technique and modified chemical vapor deposition (MCVD). The porous core layer was deposited at 1750°C with 30cm in deposition length. The soot formed at the inlet and outlet segment of the deposited length is analyzed using SEM for soot size and BET for pore size distribution. Refractive index profile of the doped preform is measured using preform analyzer. The refractive index difference obtained at the outlet and inlet segments shows uniform distribution of Al2O3, in agreement with the pore size distribution

Simulating the annual energy yield of a rotationally asymmetrical optical concentrator.

This paper simulates the annual energy yield of a concentrator called the rotationally asymmetrical dielectric totally internally reflective concentrator (RADTIRC). One specific design of the RADTIRC is assumed to be installed in Berlin/Brandenburg, Germany. Simulation and experimental work have been carried out to determine the optical concentration gain under direct and diffuse radiations. Based on the analysis, it was found that the yearly energy yield was increased by a factor of 2.29 when the RADTIRC-PV module was used when compared with the non-concentrating PV module