An investigation of the effect of changes of planning criteria on power system expansion planning with a case study of the Jordanian power system

Many factors contribute to the planning process of power systems. In the context of expansion planning, focus is paid to selection criteria that enable the optimization of related factors that will result in the best performance. This is described as meeting demand whilst reducing costs and maintaining minimal risk in operation. In this paper, different criteria used in the planning of power system expansion studies are investigated with the objective of identifying their impact on the expansion plan. The results of these criteria on the expansion study of the Jordanian power system are presented. Results show good correspondence to the actual adopted solutions. The spinning reserve is the most influential planning criterion on the overall system expansion cost. This is followed by the peak load changes, and the forced outage rate of the candidate units used for capacity additions to meet future expected demand. Finally, the loss of load expectation and cost of energy not served have the least effect on the overall system expansion cost. These results highlight the importance to be placed on performing sensitivity analyses to determine the most cost effective and acceptable expansion plan of the electric power system. There is a need to continually update the planning criteria to cater for changes and developments in the power system and the economic situation. Finally, the methodology of this study can be generalized to other power systems.     

Active Reflector for Radar Calibration

An active radar calibrator (ARC), consisting of a receive-antenna and a transmit-antenna, with an RF amplifier in between, is proposed as a tool for conducting high-precision calibration measurements of radar systems. The ARC can be designed to have a large radar cross section and a broad pattern. Its major advantages over passive reflectors are its small physical size and its suitability for calibrating radars that operate in any polarization configuration.     

Microwave Dielectric Properties of Plant Materials

Three waveguide transmission systems covering the 1-2, 3.5-6.5, and 7.5-8.5 GHz bands were used to measure the dielectric properties of vegetation material as a function of moisture content and microwave frequency. The materials measured included, primarily, the leaves and stalks of corn and wheat. Dielectric measurements also were made of the liquid included in the vegetation material after it was extracted from the vegetation by mechanical means. The extracted liquids were found to have an equivalent NaCl salinity of about 10 per mil, which can have a significant effect on the dielectric loss at frequencies below 5 GHz. The results of attempts to model the dielectric constant of the vegetation-water mixture in terms of the dielectric constants and volume fractions of its constituent parts (i. e., bulk vegetation, air, bound water, and free water) are discussed. Additionally, measurements of the temporal variations in the total attenuation at 10.2 GHz are presented for a corn canopy and a soybean canopy.     

Microwave Backscatter Dependence on Surface Roughness, Soil Moisture, And Soil Texture: Part III-Soil Tension

Results are presented of an experimental program to determine the impact of soil texture on radar response to soil moisture present within nonvegetated soil surfaces. These findings extend previous reports which document the experimental relationship between the radar backscattering coefficient ?° and soil moisture for bare soil [1] and soil under crop canopies [2]. In confirmation of previous results [1] and [2], the sensitivity of ?° to surface gravimetric or volumetric soil moisture is shown to be inversely related to clay content of the soil. As a result, gravimetric or volumetric moisture indicators exhibit poor performance in moisture estimation algorithms for complex multitextured soils. However, estimation algorithms incorporating some knowledge of soil water retention as a function of soil matric potential, or tension, display strong correlation with radar response, typically r ? 0.8, and are shown to be relatively independent of soil texture. These findings are shown to be consistent with soil dielectric properties [3]-[5].     

Modification of Silica Nanoparticles with Cysteine or Methionine Amino Acids for the Removal of Uranium (VI) from Aqueous Solution

Silicon - Silica nanoparticles (SiO2-NPs), modified silica nanoparticles with cysteine (SiO2-Cys) or methionine (SiO2-Meth) were used for sorption of uranium (VI) ion from aqueous solution. Silica...     

Coating of stainless steel and titanium bipolar plates for anticorrosion in PEMFC: A review

Anticorrosion coating for stainless steel (SS) and titanium bipolar plates were evaluated to improve the corrosion resistance and electrical conductivity in PEMFC. The PEMFC offers clean and environmentally friendly usage in electrical power systems. The bipolar plates contribute 60%–80% of the total components of PEMFC stack with electrical conductivity >100 S cm^?1. Therefore, high conductivity and corrosion resistance are observed for long-term operations in PEMFC. Recent works has developed the cost-effective and feasible alternative materials to replace graphite bipolar plates. Metallic materials, such as SS and titanium, possess good electrical conductivity but poor corrosion resistance. Coating of SS and titanium bipolar plates can improve the corrosion resistance of metallic bipolar plates. Excellent performance of bipolar plates was recorded by using NbC coating for stainless steel materials. The ICR value using plasma surface alloying method was 8.47 mΩ cm² with a low current density (I_corr) between 0.051 and 0.058 μA cm^?2. The criteria for both current densities (<1 μA cm^?2) and electrical conductivity (<10 mΩ cm²) met the DOE's 2020 technical targets. In addition, conventional air brush method can be used for fabricating multilayer coatings onto substrates because it is self-cleaning, low cost and offers high volume and large area production. Vapor deposition method, a highly advanced coating technology using PVD, suitable for coating bipolar plates because it is environmentally friendly and can be used in high temperatures, producing materials with good impact strength and excellent abrasion resistance. PEMFC cost is still too high for large scale commercialization, which is the cost of raw material and processing to allow fabrication of thinner plates contributes substantially to the total PEMFC cost. Some future works on fuel cell anticorrosion research with reasonable coating method is suggested to reduce the cost in order to facilitate the move toward commercialization especially for SS and titanium bipolar plates.     

Bordeaux-R interactions with surfactants: thermochromic investigations of proton ionisation in cationic, nonionic and anionic surfactant solutions

Apparent thermodynamic parameters for the hydroxy proton ionisation of Bordeaux-R were obtained in micellar solutions using the thermochromic method. The effect of addition of the surfactants CTAB, TX-100 and SDS was investigated in buffered solutions in the pH range of 6–13. Ionisation constants in water and in the presence of surfactants were determined spectrophotometrically and the p K ' of Bordeaux-R in water was found to be 10.90 in the absence of surfactant. However, at concentrations above critical micelle concentration, p K ' dropped to 10.14 with CTAB, increased to 11.29 with TX-100 but was insensitive to SDS addition. Standard enthalpies and entropies of ionisation were obtained using the thermochromic method. This method, in conjunction with p K and spectral measurements and comparison with different azo dyes, has been shown to provide detailed information on the mechanism of dye–surfactant interaction.     

Method for Retrieving the True Backscattering Coefficient from Measurements with a Real Antenna

Measurements made of the power backscattered by a surface at angles near nornal incidence include contributions due to both coherent and incoherent scattering. Additionally, these contributions are weighted by the antenna pattern. Using a theoretical model to describe the backscattering from a rough soil surface, a procedure is developed for retrieving the true angular pattern of the backscattering coefficient ?0 from measured estimates of a ?0 , where the measured estimate is based on the usual assumption that ?0 is approximately constant over the angular extent of the antenna beam for narrowbeam systems. The retrieved patterns of ?0 were then used to evaluate the dependence of ?0 on soil surface roughness at 1.5, 4.25, and 7.25 GHz.     

Improvement of Moisture Estimation Accuracy of Vegetation-Covered Soil by Combined Active/Passive Microwave Remote Sensing

The measured effects of vegetation canopies on radar and radiometric sensitivity to soil moisture are compared to first-order emission and scattering models. The models are found to predict the measured emission and backscattering with reasonable accuracy for various crop canopies at frequencies between 1.4 and 5.0 GHz, especially at angles of incidence less than 30°. The vegetation loss factor L (?) increases with frequency and is found to be dependent upon canopy type and water content. In addition, the effective radiometric power absorption coefficient of a mature corn canopy is roughly 1.75 times that calculated for the radar at the same frequency. Comparison of an L-band radiometer with a C-band radar shows the two systems to be complementary in terms of accurate soil moisture sensing over the extreme range of naturally occurring soil-moisture conditions. The combination of both an L-band radiometer and a C-band radar is expected to yield soil-moisture estimates that are accurate to better than +/-30 percent of true soil moisture, even for a soil under a lossy crop canopy such as mature corn. This is true even without any other ancillary information.     

A millimeter wave technique for measuring ice thickness on the Space Shuttle's external tank

The external fueltank of the Space Shuttle contains extremely lowtemperature propellents. A layer of material known as SOFI (Spray-On Foam Insulation) covering the outside of the fueltank provides thermal insulation between the aluminum surface of the fueltank and the ambient air. In spite of this insulation, under certain conditions ice formation will occur on the surface of the SOFI. Ice on the external fueltank can be detrimental to the launch and it is important to detect its presence and measure its thickness. This paper describes the design of a millimeter-wave radiometer technique developed for this purpose. The design is based on model calculations and measurements of the emission properties of a panel from the external fueltank performed at 35, 94 and 140 GHz. Two sets of measurements were performed, one for the unmodified rough-surface SOFI panel and another for a panel whose surface was sanded down to produce a smooth surface interface with the ice cover. The latter was used to evaluate the results of radiative transfer calculations which are much easier to perform for multilayer structures with plane boundaries. We present experimental evidence demonstrating that the technique developed can accurately predict ice thickness in the case of the smooth-surface SOFI panel. For the original (rough-surface) panel, the emission levels observed were considerably higher than predicted by the model. Both cases however exhibited comparable sensitivities to ice thickness (～ K/mm at 35 GHz, 4 K/mm at 94 GHz, and 5 K/mm at 140 GHz).