A Microcomputer Interactive Graphics Software for Design of Steel Trusses

Current advances in microcomputer technology provide the tools to use interactive graphics in the development of efficient computer programs. The use of computer graphics facilitates the definition of complicated engineering models, and permits a clear display of the results. In this paper, an educational microcomputer software package, TRUSS-AD, is described to demonstrate the effectiveness of applying interactive computer graphics in solving structural engineering design problems. TRUSS-AD allows the user to: (1) define a truss geometry and loading conditions graphically; (2) analyze and design the truss in an interactive mode; and (3) display all results in a concise and clear graphical representation. The stiffness method is used in the analysis process. The design can be performed by using either the "Load and Resistance Factor Design" or the "Allowable Stress Design" methods. The software is written using the basic language for IBM or compatible personal computers.     

A switched-ca pari tor delay line with self-equalizing sample-and-hold

A simple SC delay line using a three-phase clock is described. The new circuit uses a reduced number of operational amplifiers and includes a circuit for correcting the amplitude deviation arising from the sample-and-hold effect Unlike previous circuits this circuit does not affect the group-delay of the delay line. An example for a 10μS delay line in the frequency range 0-250 kHz is given.     

Remote,surface and laboratory detection of radioactive minerals of Rosetta black-sand beach deposits,Egypt

Abstract

Detailed aerial and ground radiometric surveys were conducted on the coastal plain of the Mediterranean Sea, on both sides of the estuary of the Rosetta branch of the River Nile. Auger samples representing the upper 1 m, were collected and analysed for the two principal radioactive minerals in the black sands, zircon and monazite.

The results obtained by the various methods, particularly aeroradiometry, revealed five main zones of heavy mineral concentration along the beach to the east and west of the Rosetta estuary. The present-day Rosetta branch is responsible for the formation of the first zone of mineral concentration. The second and fifth zones can be related to the ancient extinct estuaries of the Bolbitine and Sebennytic branches mentioned by Ball (1942) (after Herodotus, 450 B.C.). The third and fourth zones are believed to correspond to two ancient extinct estuaries of the River Nile, which were probably not in existence at the time of Herodotus and therefore were not reported by Ball (1942).

The study revealed that there is a general direct correlation between the aerial data and that from ground radiometry and zircon and monazite tenors as in the case of Damietta black-sand beach deposits (Meleik et al. 1978).

It was found that the mean background radioactivity either from the air or from the ground, as well as the correlation coefficients, are generally higher and stronger on the western side of the Rosetta estuary than on its eastern side. Moreover, the mean concentration of zircon on the western side (0·62 per cent) reaches approximately 1·5 times that on the eastern side (0·39 per cent), while that of monazite remains almost the same westwards (0·16 per cent) and eastwards (0·14 percent).     

Improvement of low fat mozzarella cheese properties using denatured whey protein

Mozzarella cheese was made from buffalo milk (6% fat) or from partially skimmed buffalo milk (2 and 4% fat) with 0.5 and 1% denatured whey protein. Adding whey protein to buffalo milk decreased rennet coagulation time and curd tension whereas increased curd synaeresis. Addition of whey protein to cheese milk increased the acidity, total solids, ash, salt, salt in moisture, also some nitrogen fractions. The meltability and oiling‐off values increased but the calcium values of mozzarella cheese decreased. The sensory properties of low fat mozzarella cheese were improved by addition of whey protein to the cheese milk.     

A DIAKOPTICAL TECHNIQUE FOR SHORT CIRCUIT STUDIES OF LARGE SIZE POWER SYSTEM NETWORKS

ABSTRACT

The paper presents a diakoptical technique for deriving the impedance matrices required for short circuit studies of large size power system networks by tearing the system into smaller subsystems by cutting appropriate tie lines. The bus admittance matrix is formed for the sequence networks of each subsystem and then modified later by means of diakoptics. The simulation of mutual couplings is taken into account in the zero sequence networks. Only columns of the impedance matrices corresponding to the faulted buses are computed in the proposed technique which is based on factorized bus admittance matrices and full exploitation of sparsity. The proposed technique can either be used in a single–processor computer for sequential solution of torn subsystems or in a multicomputer configuration for a faster solution by parallel processing of torn subsystems. Both symmetrical and unsymmetrical faults are studied by using the proposed technique which produces exact results as the untorn system. No iterative calculations are required as short circuit analysis is basically a linear problem. Included in this paper is a numerical example of a sample test system.