This paper proposes a new electric load forecasting model by hybridizing the fuzzy time series (FTS) and global harmony search algorithm (GHSA) with least squares support vector machines (LSSVM), namely GHSA-FTS-LSSVM model. Firstly, the fuzzy c-means clustering (FCS) algorithm is used to calculate the clustering center of each cluster. Secondly, the LSSVM is applied to model the resultant series, which is optimized by GHSA. Finally, a real-world example is adopted to test the performance of the proposed model. In this investigation, the proposed model is verified using experimental datasets from the Guangdong Province Industrial Development Database, and results are compared against autoregressive integrated moving average (ARIMA) model and other algorithms hybridized with LSSVM including genetic algorithm (GA), particle swarm optimization (PSO), harmony search, and so on. The forecasting results indicate that the proposed GHSA-FTS-LSSVM model effectively generates more accurate predi... [more]

An innovative control strategy is proposed for enhancing the low voltage ride-through (LVRT) capability of a doubly fed induction generator based on wind energy conversion systems (DFIG-WECS). Within the proposed control method, the current control loops of the rotor side converter (RSC) are developed based on passivity theory. The control scheme for the grid side converter (GSC) is designed based on a two-term approach to keep the DC-link voltage close to a given value. The first term based on the maximal voltage of GSC is introduced in the GSC control loops as a reference reactive current. The second one reflecting the instantaneous unbalanced power flow between the RSC and GSC is also introduced in the GSC control loops as a disturbance considering the instantaneous power of the grid filter to compensate the instantaneous rotor power. The effectiveness of the proposed control strategy is verified via time domain simulation of a 2.0 MW-575 V DFIG-WECS using PSCAD/EMTP. Simulation res... [more]

Tar formation is the main bottleneck for biomass gasification technology. A novel rotary kiln type biomass gasification process was proposed. The concept design was based on air staging and process separation. This concept was demonstrated on a pilot scale rotary kiln reactor under ambient pressure and autothermic conditions. The pilot scale gasifier was divided into three different reaction regions, which were oxidative degradation, partial oxidation and char gasification. A series of tests was conducted to investigate the effect of key parameters. The results indicate that under optimum operating conditions, a fuel gas with high heat value of about 5500 kJ/Nm³ and gas production rate of 2.32 Nm³/kg could be produced. Tar concentration in the fuel gas could be reduced to 108 mg/Nm³ (at the gasifier outlet) and 38 mg/Nm³ (after gas conditioning). The cold gas efficiency and carbon conversion rate reached 75% and 78%, respectively. The performance of this gasification system shows consi... [more]

The improvement of device performance of a recycling solar air heater featuring a wire mesh packing was investigated experimentally and theoretically. The application of the wire mesh packing and recycle-effect concept to the present study were proposed aiming to strengthen the convective heat-transfer coefficient due to increased turbulence. Comparisons were made among different designs, including the single-pass, flat-plate double-pass and recycling double-pass wire mesh packed operations. The collector efficiency of the recycling double-pass wire mesh packed solar air heater was much higher than that of the other configurations for various recycle ratios and mass flow rates scenarios. The power consumption increment due to implementing wire mesh in solar air heaters was also discussed considering the economic feasibility. A fairly good agreement between theoretical predictions and experimental measurements was achieved with an analyzed error of 1.07%⁻9.32%.

A procedure based on MATLAB combined with ANSYS is presented and utilized for the aerodynamic and structural integrated optimization design of Horizontal-Axis Wind Turbine (HAWT) blades. Three modules are used for this purpose: an aerodynamic analysis module using the Blade Element Momentum (BEM) theory, a structural analysis module employing the Finite Element Method (FEM) and a multi-objective optimization module utilizing the non-dominated sorting genetic algorithm. The former two provide a sufficiently accurate solution of the aerodynamic and structural performances of the blade; the latter handles the design variables of the optimization problem, namely, the main geometrical shape and structural parameters of the blade, and promotes function optimization. The scope of the procedure is to achieve the best trade-off performances between the maximum Annual Energy Production (AEP) and the minimum blade mass under various design requirements. To prove the efficiency and reliability of... [more]

Water, energy, and food are lifelines for modern societies. The continuously rising world population, growing desires for higher living standards, and inextricable links among the three sectors make the water-energy-food (WEF) nexus a vibrant research pursuit. For the integrated delivery of WEF systems, quantifying WEF connections helps understand synergies and trade-offs across the water, energy, and food sectors, and thus is a critical initial step toward integrated WEF nexus modeling and management. However, current WEF interconnection quantifications encounter methodological hurdles. Also, existing calculation results are scattered across a wide collection of studies in multiple disciplines, which increases data collection and interpretation difficulties. To advance robust WEF nexus quantifications and further contribute to integrated WEF systems modeling and management, this study: (i) summarizes the estimate results to date on WEF interconnections; (ii) analyzes methodological an... [more]

HyThSoft, was developed as a powerful tool to consent with the ”WORK PLAN FOR THE MEXICAN MANGO TREATMENT AND PRECLEARENCE PROGRAM” developed jointly by the United States Department of Agriculture, Animal and Plant Health Inspection Service, International Services (USDA/APHIS) and the Secretaria de Agricultura Ganadería y Desarrollo Rural Pesca y Alimentación (SAGARPA) and with norm NOM-075-FITO-1997. This software is designed to take temperature signals and control up to 6 treatment tanks. The software also contains logical functions which facilitate the work of the exporters and USDA/APHIS personal. Although this software was developed for treatment tanks that have each one, an independent boiler, it can also be use with a single boiler for all the tanks (dependent equipment), just by changing its operational parameters.

The dynamic response of continuous processes is a key issue for their control. To represent this
response, first order models are used, mainly because of their simplicity and the lack of simple methods for parameter estimation of higher order models. Although first order models may be sufficient in many cases, there are times when a higher order model needs to be used to achieve good control. This paper presents a simple graphical procedure for the estimation of the two time constants, the gain, and the dead time of a second order linear model. The procedure uses only four readings from the step response curve of the processes, and very simple formulas to determine parameter values.