Delay causes in Iran gas pipeline projects

On the basis of Iran's strategic development plan, natural gas industry must develop the capacity of gas transmission up to 1300 million m³ per day until 2025. For this purpose, gas pipeline length should be doubled during the next 15 years; however, experience shows a remarkable delay in nearly all gas pipeline projects. The main goal of this paper is to identify and rank the causes of delay in these kinds of projects in Iran. In this regard, 24 executed gas pipeline projects were studied and then extracted delay factors were conferred with 10 experts from several disciplines. The result was a 43-item list of factors which then was ranked by means of a questionnaire survey. The result reveals that the 10 major delay factors are: “imported materials, unrealistic project duration, client-related materials, land expropriation, change orders, contractor selection methods, payment to contractor, obtaining permits, suppliers, and contractor's cash flow”.     

Investigation of Proposed Concrete Filled Steel Tube Connections under Reversed Cyclic Loading

Concrete-filled steel tube (CFT) columns are used in the primary lateral resistance systems. The objective of this research is to analyse the behavior of the steel beam to CFT column connections. A three-dimensional numerical model for simulating the behavior of CFT connections was developed with the aid of the general purpose nonlinear finite element analysis package ABAQUS. In this paper, 90 CFT connection specimens include simple and moment connections that were tested under reversed cyclic loading. Shear capacity of joint, moment-drift response, energy absorption, and displacement ductility were studied in those models. The results have indicated that, the hysteresis curve of CFT columns was plump; no pinch phenomenon can be found; the damage and degradation degree of the strength and stiffness of specimens is lower; and high energy dissipation capacity can be achieved. Improvement in the behavior of CFT connection depends on the beam characteristics and column features.     

The wandering coronary stent. Case report

Complications associated with coronary stent placement have decreased in recent years. One of the complications involved with this procedure is the possibility that the stent is stripped from the delivery catheter prior to deployment and is lost systemically. This paper reports a rare complication which resulted in vascular insufficiency necessitating surgical intervention.     

Junctionless In0.3Ga0.7As/GaAs transistor with a shell doping profile for the design of a low-noise amplifier with a sub-1-dB noise figure for X-band applications

Journal of Computational Electronics - In this paper, a junctionless (JL) In0.3Ga0.7As/GaAs FET with a shell-doped channel (SDCh) for high-frequency electronics is investigated, and different...