Showing papers by "Istanbul Technical University published in 1980"

Remnants of a pre-Late Jurassic ocean in northern Turkey: Fragments of Permian-Triassic Paleo-Tethys?

Abstract: An ophiolitic suture zone and associated active continental margin sequences of mid-Jurassic age are found in northern Turkey exposed in inliers surrounded by an extensive Upper Cretaceous to Eocene volcanic blanket. The pre–Late Jurassic rocks of the eastern Black Sea Mountains (eastern Pontide tectonic zone) consist of two distinct lithologic associations: a “continental” assemblage represents a Permian to Early Jurassic north-facing magmatic arc, whereas an “oceanic” assemblage, including a locally metamorphosed ophiolite suite overlain by deep-sea sediments, is believed to represent the vestiges of an oceanic realm that existed north of the arc during the ?Permian to Jurassic interval. During the mid-Jurassic, the oceanic assemblage underwent penetrative deformation and was overthrust by the continental assemblage. The latter has not been penetratively deformed except for a wide zone of intense cataclasis along its basal thrust. The southern part of the continental assemblage was affected by east-west gravity faulting and basaltic and some trachytic volcanism during the Early Jurassic. We interpret the Permian to mid-Jurassic geological record of the eastern Pontides as the expression of the progressive contraction of a Permian-Jurassic ocean with a south-dipping subduction zone. Its closure resulted in the overthrusting of the continental assemblage onto the oceanic assemblage. Regional considerations suggest that the suture forms a part of an orogenic belt stretching from the mid-Jurassic South Rhodope Orogen through the early to mid-Mesozoic orogenic zones of the peri-Black Sea regions, northern Iran, Afghanistan, central Tibet, and China. This orogenic belt resulted from the closure of Permian-Triassic Paleo-Tethys. The oceanic assemblage we describe is believed to be a part of the floor of this ocean, whereas the continental assemblage is viewed as a part of a previously defined Cimmerian continent.

The numerical calculation of extreme wet and dry periods in hydrological time series / Méthode numérique d'évaluer les périodes extrêmes de desséchement et de sécheresse dans une série de temps hydrologique

Abstract: A numerical method for evaluating the possibilities of the extreme wet and the extreme dry periods of a hydrological sequence is presented on the basis of stationary independent and Markovian processes that are currently employed in the planning and operation of water resources systems. The validity of the formula has been checked against the Monte Carlo simulation results obtained on a digital computer. Recurrence relationships for the probability distribution functions of the longest wet and dry periods have been derived by direct enumeration and the statistical properties of these extremes are presented.

Nonlinear Analysis of Cold-Formed Steel Shear Diaphragms

Abstract: The method is based on residual forces. Diaphragms are modeled by finite elements of three types: (1)The individual panel units; (2)the supporting steel framing; and (3)the connectors. The connectors are considered to be the sole source of nonlinear behavior, essentially as indicated by experimental evidence. The computer program is user-oriented, and is equipped with an automatic mesh generator as well as an accelerator to improve convergence rate. Applications of the analysis to diaphragms for which full-scale test results are available show good correlation. The method provides full information on displacements and internal force distributions, as well as overall behavior, and thus provides a sound basis for the development of approximate methods suitable for manual design. It may be directly useful for the design of complex systems such as those including large openings or having unusual proportions, or for the design of innovative stressed-skin structures such as folded plates.

Stabilizing feedback gains for priority-ordered multichannel linear systems

Abstract: The feedback stabilization of a multichannel linear, time-invariant system is considered. The channels have been ordered in terms of criteria such as dependability, cost, ease of implementation, etc. A simple algorithm is presented which causes the preferred channels to assume more of the burden of stabilization.

Bit processing with FORTRAN

Abstract: Bit manipulations are not defined in the Fortran standards due to their dependency on the implemented machine. In the X3.9-1978 Fortran standard, CHARACTER statement and concatenation operator,//, are defined for byte manipulations but there are no comments on bit processing, these being left to the next standard. In this note, two routines will be given for bit processing in Fortran IV. Most Fortran compilers reserve 1,4 and 6 bytes for LOGICAL, INTEGER and REAL data types, respectively. In the case of binary data, one of these types must be used, thus, according to use 7,31 or 47 bits would be wasted. If 1 bit of binary data can be represented by one bit of the memory then considerable savings in reachable computer memory locations would be achieved. Two basic procedures are prepared for bit processing in Fortran : a) To unpack a byte (8 bits) into a Fortran integer array of 8 elements, each containing binary data (i or 0). b) To pack a Fortran integer array containing binary data into a byte. In most Fortran compilers, LOGICAL data type is the smallest addressable element, and it usually occupies one byte. Hence the proposed routines pack and unpack 1 byte (or with some small modifications, 4 bits). In the routines, given below, L denotes logical data i.e. 8 bits, and I denotes an integer array with 8 elements,[ ] indicates contents of and [ ]~ defines a hexadecimal constant. We shall also need the following hexadecimal constants, which are represented in LOGICAL declared arrays as follows : The descriptions given below follow closely the FORTRAN subroutines presented in the appendix. i. UNPACKING ROUTINE Unpacking is the process in which one byte, 8 bits, which is represented by a logical variable, L, is unpacked into 8 elements of an integer array I(8), which will contain only binary values. Eight bits or a byte can be represented by two hexadecimal digits (eg: 111001102= E6H). In the first step of the unpacking routine, the first four

Note on the modified Aitken accelerator for use in the residual force method

Abstract: Some considerations regarding the application of the modified Aitken accelerator to solution of problems of elasto-plasticity by the residual force method are discussed. An efficient technique for continuing iterations after an acceleration is given.