LAI based trees selection for mid latitude urban developments: A microclimatic study in Cairo, Egypt

To study the leaf area index, LAI, based thermal performance in distinguishing trees for Cairo's urban developments, ENVI-met plants database was used as platform for a foliage modeling parameter, the leaf area density, LAD. Two Egyptian trees; Ficus elastica, and Peltophorum pterocarpum were simulated in 2 urban sites with one having no trees, whilst the second is having Ficus nitida trees. Trees LAD values were calculated using flat leaves' trees LAI definition to produce maximum ground solid shadow at peak time. An empirical value of 1 for LAI is applied to numerically introduce LAD values for ENVI-met.Basically, different meteorological records showed improvements for pedestrian comfort and ambient microclimate of the building using F. elastica. About 40–50% interception of direct radiation, reductions in surfaces' fluxes around trees and in radiant temperature T_mrt in comparison to base cases gave preferability to F. elastica. The lack of soil water prevented evapotranspiration to take place effectively and the reduced wind speeds concluded negligible air temperature differences from both base cases except slightly appeared with the F. elastica. Results show that a flat leaves tree if does not validate LAI of 1, the ground shading would not fulfill about 50% direct radiation interception and this value can be used as a reference for urban trees selection.Further simulations were held to investigate LAI value of maximum direct radiation interception.Performing additional simulations, F. elastica of LAI of 3 intercepted almost 84% of direct radiation and revealed implications about urban trees in practice and its actual LAI.     

Separation of Paraffin Wax Using Solvent Fractionation

Abstract

In order to separate and characterize some grades of paraffin waxes from El-Ameria crude waxes (slack waxes), a one-stage fractional crystallization technique has been done to separate the paraffin waxes with different characteristics by using different solvents and solvent mixtures at ambient temperature of 20°C and fixed dilution and washing solvent ratios (S/F) of 4:1 and 2:1 by weight, respectively. The fractionating solvents used are n-hexane, methyl isobutyl ketone (MIBK), dioxane, ethyl acetate, and butyl acetate as a single solvent and a mixture of methyl ethyl ketone (MEK) containing benzene (B) and toluene (T) as a mixed solvent. The resulting data revealed that dioxane and n-hexane solvents are not suitable for fractional crystallization of slack waxes, and the most suitable solvents for separating paraffin waxes with the standard specifications are ethyl and butyl acetates, MIBK, and the mixture of MEK, B, and T (60:20:20 by weight, respectively).     

A new video magnification technique using complex wavelets with Radon transform application

Magnifying micro-movements of natural videos that are undetectable by human eye has recently received considerable interests, due to its impact in numerous applications. In this paper, we use dual tree complex wavelet transform (DT-CWT), to analyze video frames in order to detect and magnify micro-movements to make them visible. We use DT-CWT, due to its excellent edge-preserving and nearly-shift invariant features. In order to detect any minor change in object’s spatial position, the paper proposes to modify the phases of the CWT coefficients decomposition of successive video frames. Furthermore, the paper applies Radon transform to track frame micro-movements without any temporal band-pass filtering. The paper starts by presenting a simple technique to design orthogonal filters that construct this CWT system. Next, it is shown that modifying the phase differences between the CWT coefficients of arbitrary frame and a reference one results in image spatial magnification. This in turn, makes these micro-movements seen and observable. Several simulation results are given, to show that the proposed technique competes very well to the existing micro-magnification approaches. In fact, as it manages to yield superior video quality in far less computation time.     

Evaluation of a proper controller performance for maximum-power point tracking of a stand-alone PV system

In this paper the implementation of a suggested stand-alone PV system, for maximum-power point tracking (MPPT), is carried out. Also, this paper presents a comparative study, through experimental work, between the conventional PI controller and the fuzzy logic controller (FLC) under different atmospheric conditions. The implemented system with both the PI controller and the FLC gives a good maximum-power operation of the PV array, but the tracking capability for different optimum operating points is better and faster for the case of using the FLC compared to the case of using the PI controller.     

Detection of linear trends in process mean

In this paper, we develop a process control approach to detect linear trends in the process mean. A statistic based on the deviation between the target mean and the expected mean of the process is used in the development of the new approach. The statistic is shown to have a chi-square distribution. The approach is described and its performance is compared with cumulative sum (CUSUM), exponentially weighted moving average (EWMA), Shewhart, and generalized likelihood ratio (GLR) charts in detecting linear trends in the process mean. The results indicate that proposed approach is effective in detecting small to large trends. We also investigate the run length properties of the proposed approach under linear trends and compare its values with simulation results. Finally, we analyse the performance of the proposed approach in detecting the time when a drift occurs in the process and compare it with CUSUM and EWMA estimators. The results show that the proposed approach is more effective in detecting drift time for moderate and large trends.     

Modification and Re-calibration of the Simulation Model of Lake Nasser

Abstract

In 1981, a mathematical simulation model for Lake Nasser (SMLN) was developed to test different hydrologic conditions and operation policies of the Aswan High Dam (AHD). At that time, AHD had been operating for around 12 years. Over the thirty years of the dam operation, the Egyptian water resources managers experienced cycles of floods and droughts. Also, data and information about the hydrologic parameters of the lake as well as the dam performance were accumulated. This by itself constitutes a good reason for re-calibrating of the SMLN. The 1998–1999 flood, which manifested the need to reconsider the dominant operation policy, also called for the adjustment and re-calibration of the SMLN or at least to retest its accuracy. This paper describes the effort carried out to recalibrate this model using few parameters and adjust its original mathematical formulation. Elements of the mass balance equation of the lake, which are uncertain and at the same time seem to have significant impact, have been used in the modification and re-calibration. The presented results show, in many cases, an improvement in the model performance and accuracy when compared with the original version calibrated in 1981. Nevertheless, these results should not be considered a final step in improving the model performance. Actual measurements of evaporation rates and piezometric heads of the groundwater around the lake may be used to formulate new and better loss equations     

Low-sensitivity SC realization of brune and C-type reactance sections

The SC implementation of doubly terminated reactance reference filters containing Brune or C-type sections is presented. It is shown that the one-to-one correspondence between the elements of the reactance reference network and its simulated SC circuit is still maintained. Computer evaluations as well as experimental verifications have shown that the resulting structure is less sensitive with respect to parasitics. Illustrative examples are given.     

A recursive least squares algorithm for an orthogonal iir adaptive line enhancer

A novel method is described for the frequency estimation of signals from a noisy background. It is based on realizing the IIR adaptive filter as a parallel connection of discrete orthogonal sections. A fast Gauss-Newton-type recursive algorithm has also been derived to update the parameters of these orthogonal sections. It has been shown that for highly noisy signals, this approach significantly improves the frequency estimation capabilities as well as increases the overall signal-to-noise ratio of the adaptive recursive filters. Illustrative examples are given to verify these results.     

Design of odd-degree linear-phase sampled-data bandpass filters with equiripple amplitude response

This paper presents a novel approach for the design and synthesis of odd-degree sampled-data filters. Initially, an efficient iterative scheme is described for the construction of a class of selective linear-phase distributed bandpass filters with equiripple passband loss response. Then, the filter's transfer function is synthesized using classical distributed circuit networks. Finally, the equivalent switched-capacitor filter could be constructed. the resulting switched-capacitor networks are completely insensitive w.r.t. parasitic capacitances, as well as having low C_max/C_min Design tables and an illustrative example are also given.