An equation of state for cyclohexane has been developed using the Helmholtz energy as the fundamental property with independent variables of density and temperature. Multiproperty fitting technology was used to fit the equation of state to data for prT, heat capacities, sound speeds, virial coefficients, vapor pressures, and saturated densities. The equation of state was developed to conform to the Maxwell criteria for two-phase vaporliquid equilibrium states, and is valid from the triple-point temperature to 700 K, with pressures up to 250 MPa and densities up to 10.3 mol dm À3 . In general, the uncertainties (k ¼ 2, indicating a level of confidence of 95%) in density for the equation of state are 0.1% (liquid and vapor) up to 500 K, and 0.2% above 500 K, with higher uncertainties within the critical region. Between 283 and 473 K with pressures lower than 30 MPa, the uncertainty is as low as 0.03% in density in the liquid phase. The uncertainties in the speed of sound are 0.2% between 283 and 323 K in the liquid, and 1% elsewhere. Other uncertainties are 0.05% in vapor pressure and 2% in heat capacities. The behavior of the equation of state is reasonable within the region of validity and at higher and lower temperatures and pressures. A detailed analysis has been performed in this article. Ó 2014 by the U.S. Secretary of Commerce on behalf of the United States. All rights reserved. [http://dx.doi.
Flood forecasting plays an important role in flood control and water resources management. Recently, the data-driven models with a simpler model structure and lower data requirement attract much more attentions. An extreme learning machine (ELM) method, as a typical data-driven method, with the advantages of a faster learning process and stronger generalization ability, has been taken as an effective tool for flood forecasting. However, an ELM model may suffer from local minima in some cases because of its random generation of input weights and hidden layer biases, which results in uncertainties in the flood forecasting model. Therefore, we proposed an improved ELM model for short-term flood forecasting, in which an emerging dual population-based algorithm, named backtracking search algorithm (BSA), was applied to optimize the parameters of ELM. Thus, the proposed method is called ELM-BSA. The upper Yangtze River was selected as a case study. Several performance indexes were used to evaluate the efficiency of the proposed ELM-BSA model. Then the proposed model was compared with the currently used general regression neural network (GRNN) and ELM models. Results show that the ELM-BSA can always provide better results than the GRNN and ELM models in both the training and testing periods. All these results suggest that the proposed ELM-BSA model is a promising alternative technique for flood forecasting.
The establishment of the ASEAN Economic Community (AEC) at end-2015 has brought into sharp focus the issue of financial and economic integration in the region. This paper takes stock of ASEAN's financial integration and prospects. ASEAN integration could accelerate in the years ahead; it will likely be a safe, gradual process consistent with the "ASEAN way" of consensus decision-making. Properly phased and sequenced, closer financial integration has the potential to help increase real incomes and accelerate real convergence within ASEAN and narrow the region's gap with advanced Asia. Realizing the promise of financial integration will require ASEAN countries to make long-term investments in financial infrastructure. Policymakers can draw on the experience of their more advanced peers and of other regions. Gradualism and safeguards should not be excuses for inaction or financial protectionism. Reliance on flexible policy frameworks and a strengthened and tested regional financial safety net should be part of the agenda. Closer engagement with the Fund could also help.
Fluoroethane (R161, C 2 H 5 F, 353-36-6) is a potential alternative refrigerant with excellent cycle performance, with zero ozone-depletion potential and low global warming potential. In this study, the thermodynamic property formulation for fluoroethane has been developed with the use of available experimental thermodynamic property data. In determining the equation of state, multiproperty fitting methods were used including single-phase pressure-density-temperature ( pρT ), vapor pressure, and saturated liquid-density data. The equation of state has been developed to conform to the Maxwell criterion for two-phase liquid-vapor equilibrium states, and is valid for temperatures from 130 K to 450 K, and pressures to 5 MPa. The extrapolation behavior of the equation of state at high temperatures and high pressures is reasonable. As there are very few compressed liquid-density experimental data published, the uncertainties in density of the equation of state are estimated to be 2.0 % in the compressed-liquid region and 0.5 % in the gas and supercritical regions. Uncertainties in vapor pressure are 0.5 % above 200 K and increase at lower temperatures. The uncertainties for all properties are higher in the critical region, except vapor pressure. Detailed comparisons between experimental and calculated data have been performed in this study.
A new fundamental equation of state explicit in the Helmholtz energy is presented for 1,1,1,3,3-pentafluoropropane (R-245fa), based on recent experimental data for vapor pressures, densities, and sound speeds. The functional form uses Gaussian bell-shaped terms, according to recent trends in the development of accurate equations of state. The independent variables of the equation of state are temperature and density. The equation is valid for temperatures between the triple point (170.0 K) and 440 K, and for pressures up to 200 MPa. Estimated uncertainties in this range are 0.1% for vapor pressures, 0.1% for saturated liquid densities, 0.1% for liquid densities below 70 MPa, 0.2% for densities at higher pressures, 0.3% for vapor densities, 0.3% for liquid sound speeds, and 0.1% for vapor sound speeds. The uncertainties in the critical region are higher for all properties except vapor pressures. The equation shows reasonable extrapolation behavior at extremely low and high temperatures, and at high pressures. C 2015 by the U.S. Secretary of Commerce on behalf of the United States. All rights reserved. [http://dx.F. 4. Percentage deviations between experimental data for vapor pressure and calculated values with the new equation of state: (+) Defibaugh and Moldover, 13 (×) Sotani and Kubota, 14 ( ) Bobbo et al., 15 (⃝) Di Nicola, 16 ( ) Bobbo et al., 17 ( * ) Grebenkov et al., 10 (•) Wang and Duan, 18 (■) Pan et al., 19 ( ) Feng et al., 20 (⊗) Zhang et al., 21 (⊕) Maruko et al., 22 ( ) Higashi and Akasaka, 11 (-) Lemmon and Span. 7
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