Robust pole placement using firefly algorithm

In this paper, the new automatic tool that is based on the firefly algorithm whose purpose is optimization of pole location in the control of state feedback has been presented. The aim is satisfying specifications of performance like settling and rise time, steady state as well as overshoot error. Utilization of Firefly algorithm has demonstrated the benefits of controllers based on this kind of time domain over controllers based on the frequency domain like Proportional-Integral Derivative (PID). The presented method is more particular for the multi-input multi-output (MIMO) systems that have substantial state numbers. The simulation results indicated that the proposed method had superior performance in providing solution to the problems that involved stabilization of helicopter under the Rationalized Model of helicopter/ Moreover, it demonstrates the Firefly algorithm effectiveness with regards to, the state observer design and feedback controller and auto-tuning

Street trading in the shadows of the Arab Spring

This paper examines the Arab revolutions of 2011 in Tunisia and Egypt, and their impact on street traders in Tunis and Cairo. Drawing on the literatures on urban conflict and resilience, the paper argues that the authoritarian regimes that the revolutions deposed left a vacuum in governance in which street traders found it hard to profit from the idealism and opportunism of an emerging new order. Despite being hindered by their lack of organization and voice, and disruption to their trade during the revolutions, street traders displayed resilience through small-scale adaptations to their trade and absorbed newcomers into the sector in the face of political conflict

Dynamic thermal model for proton-exchange membrane fuel cell

In this paper, a mathematical model is developed to simulate the transient phenomena in a polymer electrolyte membrane fuel cell (PEMFC) system. Large transient changes are expected for practical application such as transportation vehicles due to acceleration and deceleration. Simple models are usually unable to capture these transient dynamics. For control purposes, a fuel cell model must include the dynamics of flow and pressure in the anode and cathode channels and mass/heat transfer transients. The proposed model can predict the transient response of cell voltage, temperature of the cell, hydrogen/oxygen out flow rates and cathode and anode channel pressures under sudden change in load current. It is implemented in SIMULINK environment. The model is tested by simulating a transportation-size fuel cell with 85 kW maximum power output. Results for maximum power and multi-step input current that simulate start up-shut down cycle are shown. The predicted power, pressure and temperature are matching the published data for the fuel cell. The model will be very useful for the optimal design and real-time control of PEM fuel cell systems in practical automotive or stationary applications

The geology and geochronology of Al Wahbah maar crater, Harrat Kishb, Saudi Arabia

Al Wahbah is a large (∼2.2 km diameter, ∼250 m deep) maar crater in the Harrat Kishb volcanic field in western Saudi Arabia. It cuts Proterozoic basement rocks and two Quaternary basanite lava flows, and is rimmed with an eroded tuff ring of debris from the phreatomagmatic explosion that generated the crater. A scoria cone on the northern wall of the crater was dissected by the explosion and exposes a dolerite plug that was intruded immediately prior to crater formation. The dolerite plug yields a <sup>40</sup>Ar/<sup>39</sup>Ar age of 1.147 ± 0.004 Ma. This is the best possible estimate of the time Al Wahbah crater formed. It is a few tens of thousand years younger than the age of the lower and upper basalt flows, 1.261 ± 0.021 Ma and 1.178 ± 0.007 Ma respectively. A dolerite dyke exposed within the basement in the wall of the crater is dated at 1.886 ± 0.008 Ma. This is the most precise age so far determined for the initiation of basaltic volcanism of Harrat Kishb, and confirms that it is significantly younger than the other post-rift volcanic provinces in the region. This study provides constrains the timing of humid climatic conditions in the region and suggests that the Quaternary basaltic volcanism that stretches the length of the western side of the Arabian peninsula may prove to be useful for establishing palaeoclimatic conditions

Synthesis and anti-Aphid Aphis gossypii (Glover) activity of some new quinoline derivatives

A series of quinoline derivatives have been elaborated fromreaction of 2-(m- and p-acetylanilino)-quinolines 6a-b withaldehydes under Claisen-Schmidt conditions followed by cyclization with phenyl hydrazine and hydroxylamine. Reaction of  6a and 6b with hydrazine, semicarbazide and thiosemicarbazide, cyanoacetylhydrazide and subsequent some condensation reactions led to diverse quinoline derivatives. Anti aphid  Aphis gossypii that harm cotton cropin Egypt was screened. Compound  12 showed an LC50 value of 19429E-10 ppm which is very more active than Marshal (Carbosulfan), one of the broad spectrum insecticides widely used in this field

Development of generic algorithm in wheel-typed hybrid rocket grain design for performance estimation

Hybrid rockets are featured by restarting capability, increased safety, high performance and moderate cost. These combined unique characteristics pose then as prominent candidates to replace solid rockets in tactical missiles and launch vehicles in the near future. However, the behavior of hybrid rockets is not fully understood, with issues specifically related to combustion instability and lowered regression rate. To investigate the characteristics of hybrid rocket performance we develop generic algorithm code. This script may serve as a valuable teaching resource in hybrid rocket motor design. This paper uses Hydroxyl Terminated Polybutadiene (HTPB) as a solid fuel and liquid oxygen as an oxidizer for evaluation purposes. Later, we introduce the results of the preliminary design and performance analysis of the hybrid rocket system. An interior ballistic model was used for the analysis of hybrid rocket performance. MATLAB® environment was used to develop the design and performance analysis codes, and visualize the temporal variation of performance characteristics

Continuous dynamic monitoring of an offshore wind turbine on a monopile foundation

In order to minimize O&M costs and to extend the lifetime of offshore wind turbines it will be of high interest to continuously monitor the vibration levels and the evolution of the frequencies and damping ratios of the first modes of the foundation structure. This will allow us to identify and avoid resonant behavior and will also be able to give indications about the current state of the offshore wind turbine. State-of-the-art operational modal analysis techniques can provide accurate estimates of natural frequencies, damping ratios and mode shapes. To allow a proper continuous monitoring during operations a fast and reliable solution, which is applicable on industrial scale, needs to be developed. The methods need also to be automated and their reliability improved, so that no human-interaction is required and the system can track changes in the dynamic behavior of the offshore wind turbine. This paper will present and discuss the approach that will be used for the long-term monitoring campaign on an offshore wind turbine in the Belgian North Sea