Empirical Equations of P-Wave Velocity in the Shallow and Semi-Deep Sea Sediments from the South China Sea

Three-hundred and thirty-one sediment cores,including six sediment types(clayey-and sandy-silt,silty-and sandy-clay,clayey-and silty-sand)were collected from the shallow and semi-deep seas of the South China Sea,and the P-wave velocities and physical properties of core sediments were measured under standard laboratory conditions.To eliminate the influence of environ-mental factors,the empirical sound speed ratio equations were established.Compared with several equations from literature,the po-rosity and wet bulk density empirical equations established in this paper agree well with Richardson and Briggs(2004)’s in-situ equations,which implies that our empirical equations can be used in the similar region of world’s oceans under certain conditions and will be useful in areas lacking first-hand P-wave speed data.However,the mean grain size equations established in this study,similar to the previous studies,have low accuracy,which may be due to the different particle arrangements and degrees of compac-tion in sediments.The results also show that for different sediment types,the equation based on all sediment data is in good agree-ment with the measured data in the study area,as there are both siliciclastic and carbonate sediments on the studied seabed.It is sug-gested that appropriate empirical equations should be selected according to sediment types and sedimentary environment in future works,and the empirical equation of porosity or the two-parameter equation of porosity and grain size should be preferred.

Is the Two-Color Method Superior to Empirical Equations in Refractive Index Compensation?

The Edlén empirical equations and the two-color method are the commonly used approaches to converting a length measured in air to the corresponding length in vacuum to eliminate the influence of the refractive index of air. However, it is not well known whether the two-color method is superior to empirical equations in refractive index compensation. We investigated the uncertainties of these approaches via numerical calculations of their sensitivity coefficients of environmental parameters. On the basis of a comparison of their uncertainties, we found that in a 0% humidity environment, the two-color method had potential to provide greater measurement accuracy than the empirical equations.

Study of the aggregation of 1-alkanoylperylenes in 1,4-dioxane-H_2O binary solvents-Derivation of a new empirical equation relating CAgC to both chain-length and solvent aggregating power

Aggregation behaviors of 1-alkanoylperylenes (Pe-n, n = 4, 8,12) driven by hydrophobic-lipophilic interaction (HLI) have been investigated in dioxane (DX )-H2O binary aquiorgano solvents by means of fluorescence spectroscopy. A novel empirical equation, which rationalizes CAgC (critical aggregate concentration) dependence of the aggregates both on the chain-length of the substituent alkyl group and on the solvent aggregating power (SAgP) for Pe-n, has been derived.

Viscosity prediction in selected Iranian light oil reservoirs:Artificial neural network versus empirical correlations

Viscosity is a parameter that plays a pivotal role in reservoir fluid estimations. Several approaches have been presented in the literature （Beal, 1946; Khan et al, 1987; Beggs and Robinson, 1975; Kartoatmodjo and Schmidt, 1994; Vasquez and Beggs, 1980; Chew and Connally, 1959; Elsharkawy and Alikhan, 1999; Labedi, 1992） for predicting the viscosity of crude oil. However, the results obtained by these methods have significant errors when compared with the experimental data. In this study a robust artificial neural network （ANN） code was developed in the MATLAB software environment to predict the viscosity of Iranian crude oils. The results obtained by the ANN and the three well-established semi-empirical equations （Khan et al, 1987; Elsharkawy and Alikhan, 1999; Labedi, 1992） were compared with the experimental data. The prediction procedure was carried out at three different regimes： at, above and below the bubble-point pressure using the PVT data of 57 samples collected from central, southern and offshore oil fields of lran. It is confirmed that in comparison with the models previously published in literature, the ANN model has a better accuracy and performance in predicting the viscosity of Iranian crudes.

Novel empirical correlations for estimation of bubble point pressure,saturated viscosity and gas solubility of crude oils

Knowledge of petroleum fluid properties is crucial for the study of reservoirs and their development. Estimation of reserves in an oil reservoir or determination of its performance and economics requires a good knowledge of the fluid physical properties. Bubble point pressure, gas solubility and viscosity of oils are the most important parameters in use for petroleum and chemical engineers. In this study a simple-to-use, straight-forward mathematical model was correlated on a set of 94 crude oil data. Three correlations were achieved based on an exponential regression, which were different from conventional empirical correlations, and were evaluated against 12 laboratory data other than those used for the regression. It is concluded that the new exponential equation is of higher precision and accuracy than the conventional correlations and is a more convenient mathematical formulation.

Liquidus Temperatures of System Na_3AlF_6-K_3AlF_6-AlF_3 for Aluminum Electrolysis at Lower Temperature

Liquidus temperatures in the molten salt system Na3AlF6-K3AlF6-AlF3 of interest for aluminum electrolysis were determined by thermal analysis method. The results were presented and an empirical equation describing liquidus temperatures for primary crystallization was derived t=1003.5–0.081×A2.3159–5.87×B0.657–0.024×A2.22×B1.14＋ 0.035×A2.17×B1.084, where t is the liquidus temperature in degree Celsius, A denotes the mass fraction of AlF3 in system Na3AlF6-K3AlF6- AlF3, and B denotes K3AlF6/（Na3AlF6＋K3AlF6 ） in mass（%, the value was defined as KR in this paper）. The composition limitations are 0w（AlF3）30%, and 0KR50%. The isothermal diagram of molten salt system Na3AlF6-K3AlF6-AlF3 was obtained in this composition limitation.

The sound velocity and bulk properties of sediments in the Bohai Sea and the Yellow Sea of China

In order to investigate the correlation between a sound velocity and sediment bulk properties and explore the influence of frequency dependence of the sound velocity on the prediction of the sediment properties by the sound velocity, a compressional wave velocity is measured at frequencies of 25-250 kHz on marine sediment samples collected from the Bohai Sea and the Yellow Sea in laboratory, together with the geotechnical parameters of sediments. The results indicate that the sound velocity ranges from 1.232 to 1.721 km/s for the collected sediment samples with a significant dispersion within the series measuring frequency. Poorly sorted sediments are highly dispersive nearly with a positive linear relationship. The porosity shows a better negative logarithmic correlation with the sound velocity compared with other geotechnical parameters. Generally, the sound velocity increases with the increasing of the average particle size, sand content, wet and dry bulk densities, and decreasing of the clay content, and water content. An important point should be demonstrated that the higher correlation can be obtained when the measuring frequency is low within the frequency ranges from 25 to 250 kHz since the inhomogeneity of sediment properties has a more remarkably influence on the laboratory sound velocity measurement at the high frequency.

Study on Anticipant Mature Age of Pinus tabuliformis in Shandong Province

Through analysis on materials, the fitting empirical equation for growth process of Pinus tabuliformis was obtained, i.e. , the function with increment as variable and time as the independent variable. The mature age of P. tabuliformis was obtained by mathematical operation. The mature age of forest plantation was determined as 61 a, and that of public welfare forest was 81 a. And P. tabuliformis age groups were divided according to related technical requirements.

Discussion on Individual Expected Maturity Age of Populus tomentosa Carr

Through the study of parse wood materials in Shandong Province, the fitting empirical equation of tree growth was obtained, a function with tree growth was a variable and time as an independent variable. Through mathematical operations such as function derivation, the mature age of tree growth was obtained. The obtained expected maturity age for Populus tomentosa forest was 11 a for pulp material, 26 a for pillar materials and 41 a for peeler. And the application, research directions and precautions of the mature ages were proposed.

Minimum Reservoir Water Level in Hydropower Dams

Vortex formation over the intakes is an unde- sirable phenomenon within the water withdrawal process from a dam reservoir. Calculating the minimum operating water level in power intakes by empirical equations is not a safe way and sometimes contains some errors. Therefore, current method to calculate the critical submergence of a power intake is construction of a scaled physical model in parallel with numerical model. In this research some pro- posed empirical relations for prediction of submergence depth in power intakes were validated with experimental data of different physical and numerical models of power intakes. Results showed that, equations which involved the geometry of intake have better correspondence with the experimental and numerical data.

Moraine-dammed glacial lake changes during the recent 40 years in the Poiqu River Basin,Himalayas

Glacier retreat is not only a symbol of temperature and precipitation change, but a dominating factor of glacial lake changes in alpine regions, which are of wide concern for high risk of potential outburst floods. Of all types of glacial lakes, moraine-dammed lakes may be the most dangerous to local residents in mountain regions. Thus, we monitored the dy- namics of 12 moraine-dammed glacial lakes from 1974 to 2014 in the Poiqu River Basin of central west Himalayas, as well as their associated glaciers with a combination of remote sensing, topographic maps and digital elevation models （DEMs）. Our results indicate that all monitored moraine-dammed glacial lakes have expanded by 7.46 km2 in total while the glaciers retreated by a total of 15.29 km2 correspondingly. Meteorological analysis indicates a warming and drying trend in the Nyalam region from 1974 to 2014, which accelerated glacier retreat and then augmented the supply of moraine-dammed glacial lakes from glacier melt. Lake volume and water depth changed from 1974 to 2014 which indicates that lakes Kangxico, Galongco, and Youmojanco have a high potential for outburst floods and in urgent need for continuous moni- toring or artificial excavation to release water due to the quick increase in water depths and storage capacities. Lakes Jialongco and Cirenmaco, with outburst floods in 1981 and 2002, have a high potential risk for outburst floods because of rapid lake growth and steep slope gradients surrounding them.

Study on the Practical Mature Age of Individual Platycladus orientalis

This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree growth rate was used as the variable and time as the independent variable. The arithmetical operation to the function got the mature age of tree growth, and the mature ages of the timer forest, the protection forest and the special-purpose forest of Platycladus orientalis were 71, 111 and 141 a, respectively. In addition, the application as well as the research direction and matters needing attention were proposed.

Study on Correlation between Increment of Larix gmelinii and Annual Precipitation

Through the study on data of analytic tree, the fitting empirical equation for tree growth was obtained, i.e. , the function with increment as variable and annual precipitation as the independent variable. The threshold value of annual precipitation for tree growth was obtained through mathematical operation including derivation. It was concluded that Larix gmelinii grows the fast under the annual precipitation of about 545.1 mm, and negative growth would occur if the annual precipitation is lower than 349 mm and higher than 1 132.8 mm. Furthermore, the application value, research direction and matters needing attention were pointed out.

Study on the Practical and Ideal Mature Age of Pinus densiflora

This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree growth rate was used as the variable and time as the independent variable. The arithmetical operation to the function got the mature age of tree growth, and the practical and ideal mature ages of Pinus densiflora were 58 and 123.5 a, respectively. In addition, the application research direction and matters needing attention were proposed.

Study on Mature Age of An Individual Robinia pseudoacacia

Through the study of parse wood materials, the fitting empirical equation of tree growth was obtained, a function with tree growth as a variable and time as an independent variable. The mature age of tree growth was obtained through mathematical operations such as function derivation. The obtained expected maturity ages for the actual forests of Robinia pseudoacacia were 36, 46 and 56 a, respectively, which could be the mature ages for commercial forest, protection forest and special-purpose forest. And the application, research directions and precautions of the mature ages were proposed.

Study on Practical Mature Age of Individual Pinus thunbergii×P. densiflora

This study was conducted on the analytic tree and got the fitting empirical equation of tree growth, in which the tree increment was used as the variable and time as the independent variable. The arithmetical operation to the function gave the mature age of tree growth, and the practical mature age of Pinus thunbergii×P. densiflora was 41 a. In addition, the application as well as the research direction and matters needing attention were proposed.

Study on Mature Age of An Individual Pinus thunbergii Parl

Through the study of parse wood materials, the fitting empirical equation of tree growth was obtained, a function with tree growth as a variable and time as an independent variable. Through mathematical operations such as function derivation, the mature age of tree growth was obtained. The obtained maturity age for the actual forest of Pinus thunbergii Parl was 51 a, and the ideal mature age was 66 a. And the application, research directions and precautions of the mature ages were proposed.

Discussion on Individual Expected Maturity of Populus canadensis Moench

Through the study of parse wood materials in Shandong Province, the fitting empirical equation of tree growth was obtained, a function with tree growth was a variable and time as an independent variable. Through mathematical operations such as function derivation, the mature age of tree growth was obtained. The obtained expected maturity age for Populus canadensis Moench forest was 11 a for pulp material, 26 a for pillar materials and 41 a for peeler. And the application, research directions and precautions of the mature ages were proposed.

Effects of Light on Tree Growth

Empirical equations were used to fit tree growth through the analysis of parse wood data, functions with tree growth amount as the dependent variable and annual sunshine duration as the independent variable. According to arithmetical operations like derivation of the functions, the relative contribution rate of light to tree growth was 64.8%, which was almost equal to the relative contribution rate of precipitation to tree growth. Therefore, the light and precipitation were of equal importance to tree growth.

Statistical Analyses and Geotechnical Evaluation of Nubia Sandstone, Golden Triangle Area, Egypt

Great efforts had been made to use indirect non-destructive tests in the geotechnical evaluation of rocks, especially sandstones, employing different empirical equations. However, most of these equations have been derived from hard and compacted sandstones data;therefore, the focus of this research is on weak and weakly compacted sandstones, aiming firstly to obtain empirical equations for estimating their characteristics, secondly to demonstrate and visualize the correlations between the studied variables, and finally to cluster the studied samples based on their characteristics. To attain these aims, twenty oriented block samples were collected from Nubia sandstone, central Eastern Desert, Golden Triangle area, Egypt. These samples were prepared and tested according to standard test methods, including uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), Schmidt rebound number (SRN), porosity (n), bulk density (ρ), and ultrasonic P-wave velocity (UPV). The loss on ignition (LOI) was also employed as a physicochemical test for classifying the studied samples and indicating pores filling materials. The results revealed that these sandstones are characterized mainly by high n, low ρ, and low UPV values and these give an indication of weakly compacted and weakly cemented sandstone with shallow burial diagenetic conditions. Based on UCS and elastic modulus values, these sandstones are mainly classified as very low strength and highly yielding rocks. The results of regression analysis show satisfactory correlations between physical and mechanical characteristics, indicating the suitability of obtained empirical equations to deduce these properties. Principal component analysis revealed that the LOI, BTS, SRN, and USC have a positive correlation to each other and weakly correlated with ρ and UPV, which positively correlated to each other and negatively correlated to n. The results of agglomerative hierarchical clustering revealed that the studied samples can group into three main clusters depending on their USC, LOI, and n values.