Search

Calculation of phase and chemical equilibria is of fundamental importance for the design and simulation of chemical processes. Methods of minimizing the Gibbs free energy provide equilibrium solutions that are candidates only for the true equilibrium solution, because the number and type of phases must be assumed before the Gibbs energy minimization problem can be formulated. The tangent plane stability criterion was used to determine the stability of a candidate equilibrium solution. The Gibbs energy minimization and tangent plane stability problems are challenging due to highly nonlinear thermodynamic functions. This work develops a global optimization approach for the tangent plane stability problem that provides a theoretical guarantee about the stability of the candidate equilibrium solution with computational efficiency. Cubic equations of state were used due to their ability to accurately predict the behavior of nonideal vapor and liquid phases across a broad range of pressures. The mathematical form of the stability problem was analyzed and nonlinear functions with special structure were identified to achieve faster convergence of the algorithm. This approach, when applied to the SRK, Peng-Robinson, and van der Waals cubic equations of state, could address a variety of mixing rules. Computational results on problems with two-eight components are presented.

n/a

Role of heat storage in evaporation studied; observed data show that when Winnemucca Lake approached dryness and adjacent Pyramid Lake still exceeded depth of 200 ft, annual evaporation from 2 lakes was same; however, monthly quantities differ as result of heat storage in deeper lake.

Summary Earthquake focal plane solutions are computed using P wave first motion, S wave polarization angles, and combinations of the two. The method used is based on a maximum-likelihood argument implemented by the generation of a score surface on a discrete grid. The combined score is of the form a(P-score)+b(S-score). For the P-solution and S-solution, the computer system also produces contoured fiducial regions about the poles of the focal planes. This permits an evaluation of the quality of the solutions and makes possible the comparison of solutions for different earthquakes. These contoured limits have a probabilistic interpretation as 95 per cent fiducial regions, a term explained by Pope. A new graphical method for P wave solutions makes possible the construction of exact boundaries of the regions. The Aleutian earthquake of 1969 May 14, is analysed, and the solution shows good agreement between the observed P wave first motions and the S polarization angles.

A fault plane solution was made using Byerly’s extended distance technique. The A plane has a northeast strike with a northwest dip; the B plane has a southeast strike with a southwest dip. Both solutions show mainly strike slip motion. The relation of this fault plane solution to regional tectonics is discussed. Good correlation was noted between observed building damage, tension cracks, and Recent geology; assuming the B plane represents the faulting in the earthquake.

The membership of the Committee was increased in 1938 by the addition of E. W. Lane. The present membership is as follows: Harry F. Blaney, N. W. Cummings, Robert Follansbee, J. A. Folse, S. T. Harding, Robert E. Horton, Ivan E. Houk, E. W. Lane, R. E. Kennedy, G. F. McEwen, Carl Rohwer, C. M. Saville, Thorndike Saville. The Committee's recommendations for a program of investigations in evaporation from water-surfaces were the basis of the Committee's report in April 1938. This report recommended that such work should be undertaken adjacent to some large water-area for which the evaporation could be measured. No means of financing such a program has been found. In July 1938 a Class A Weather Bureau pan and a screened pan were installed adjacent to Lake Elsinore in Southern California. This represents a start toward the type of study recommended.

The membership of the Committee has remained unchanged from the previous year. It is as follows: Harry F. Blaney, 447 Pacific Electric Building, Los Angeles, California N. W. Cummings, San Bernardino Valley Junior College, San Bernardino, California Robert Follansbee, 403 New Post Office, Denver, Colorado J. A. Folse, Museum of Science and Industry, 56th Street and Lake Michigan, Chicago, Illinois Robert E. Horton, Voorheesville, New York Ivan E. Houk, U.S. Bureau of Reclamation, Customhouse, Denver, Colorado R. E. Kennedy, 1577 Jasmine Street, Denver, Colorado G. F. McEwen, Scripps Institution of Oceanography, La Jolla, California Carl Rohwer, Colorado State College, Fort Collins, Colorado C. M. Saville, 53 North Beacon Street, Hartford, Connecticut Thorndike Saville, New York University, University Heights, New York S. T. Harding, 12 Engineering Building, Berkeley, California, Chairman. The Committee on Evaporation from Water-Surfaces has commented in its previous reports on the need for more complete investigations of the factors affecting evaporation and the equipment used for its measurement. Owing to the wide distribution of its membership the Committee has not been able to hold meetings as a whole. Fortunately in June 1937, six members were in Denver at the meeting of the Section of Hydrology and were able to hold a partial meeting. It was agreed by those present that the program of the Committee, for 1937 should consist of an attempt to prepare a definite program for an adequate study of evaporation from water-surfaces. It is hoped that the presentation of such a program would assist in calling attention to the need for such work and in finding some means for undertaking it. The results of the Committee's work on this subject are attached and constitute the main results of its activity during 1937.

During the past year two members have been added to this Committee, Messrs. Blaney and Harding. The present list of members is as follows: Harry F. Blaney, 600 Federal Building, Los Angeles, California; N. W. Cummings, San Bernardino, California; R. E. Kennedy, Denver, Colorado; H. H. Kimball, Washington, D. C.; G. F. McEwen, La Jolla, California; Burt Richardson, La Jolla, California; Carl Rohwer, Fort Collins, Colorado; C. M. Saville, Hartford, Connecticut; Thorndike Saville, New York, New York; C. V. Theis, Washington, D. C.; S. T. Harding, Berkeley, California. Two papers on evaporation were presented at the meeting of the Section of Hydrology at Pasadena, California, February 1, 1936. These were both entitled “Evaporation from water-surfaces: Status of present knowledge and need for further investigations,” the authors being N. W. Cummings and A. A. Young.

The organization of the Committee on Lakes was completed during the year with the following membership: Thomas C. Adams C. S. Howard Ralf R. Woolley Phil E. Church Adolph F. Meyer S. T. Harding, Chairman Each member of the Committee has continued his own investigations in the field of lakes to such extent as war-conditions have permitted. No general Committee programs have been undertaken because of the same conditions. It is planned to maintain the organization of the Committee so that it may be available for work in its field when general investigational work can be resumed, [See p. 808 for addendum by RALF R. WOOLLEY.]

Direct penetration of rainfall to the ground-water has long been recognized as an important source of many ground-water supplies. This subject, with the results of experiments begun in 1833, was discussed in the Proceedings of the Institute of Civil Engineers in 1850 [see 1 of references at end of paper]. The portion of the rainfall which penetrates to the ground-water is the residual item after all other uses of rainfall have been met. It is the part of the rainfall which is absorbed by the soil and not used as plant-transpiration or soil-moisture evaporation. Such deeply penetrating rainfall is equivalent to the permanently absorbed water as defined by Lee [2]. Direct accretions to ground-water from rainfall, as the term is used herein, is limited to such accretions from the area on which the rain falls. Even with small amounts of rainfall there is always some concentration of runoff in low areas from which some deep penetration may occur. This may be an important item in some areas; it is small on flat areas, for small rains or on coarse soils.

Much work has been done on measurements of evaporation from tanks and the coefficients which should be used to reduce such tank-observations to the evaporation from large water-surfaces. This work has made available fairly dependable methods and records from which the probable evaporation from large water-surfaces in nearly all areas can be estimated as closely as may be essential in most water-supply studies. However, all such methods involve factors of adjustment and are necessarily less satisfactory than direct records from such large water-surfaces.

The Committee on Lakes has continued during the past year without change in membership. While it has not had any directly sponsored committee program, some of its members have been active in the field of the Committee's subject matter. Phil E. Church has continued his work on temperatures and other items in Lake Michigan. The results have been presented In publications of the University of Chicago and before technical societies. Church's paper at the Annual Meeting of 1945 indicated the scope of this work and some of its results.

These three excellent papers present the ground-water conditions and problems or the San Joaquin Valley from three different points of view. Taken together they comprise a very good picture of the ground-water resources of the Valley. As the water-supply problems of the San Joaquin Valley are more acute in the portion of the Valley south of Chowchilla River it is natural that the authors devote more of their discussion to this portion. This should not cause us to lose sight of the fact that a large part of the best development in the Valley is in its northern part where nature has been more liberal in providing an adequate water-supply.

The membership of the Committee on Lakes continued without change during the year. Group action by the Committee has not been undertaken because of the War. Each member has continued such work in this field a s his other activities have permitted. Phil E. Church has continued his work on the results of observations on Lake Michigan. His second paper on the “Annual temperature cycle of Lake Michigan, D: Spring warming and summer stationary period, 1942,” has been completed and is at present in press. It will be published as Miscellaneous Report 18 of the Department of Meteorology, University of Chicago, The paper consists of a discussion of the warming phase of a deep, fresh-water lake. One more report on this lake is being written; it will discuss autumnal cooling and the change of heat-content of the lake for the year 1941–42.