We propose a systematic method for creating constellations of unitary space–time signals for multiple-antenna communication links. Unitary space–time signals, which are orthonormal in time across the antennas, have been shown to be well-tailored to a Rayleigh fading channel where neither the transmitter nor the receiver knows the fading coefficients. The signals can achieve low probability of e...

he empirical studies have shown that cost advantages can occur due to economies of scale and economies of learning. However, a few studies have attempted to distinguish between these two effects on reducing costs. This paper is the first attempt on recognizing the impact of learning on reducing the cost with distinguishing the effect of economies of scale in Iran. Therefore, this study aims to ...

BACKGROUND Work-related musculoskeletal disorders (WMSDs) are a common health problem throughout the world and a major cause of disability in the workplace. OBJECTIVE To determine the prevalence rate of MSDs, assessment of ergonomics working conditions and identification of major risk factors associated with MSDs symptoms among employees of Iranian petrochemical industries between October 200...

BACKGROUND Human Development Index (HDI) is a composite indicator that can show the impact of economic strategies on human life standards. The index is calculated by three main factors of income, education and health. This research studies the status of HDI across the Iranian provinces, its changes over time and the efficiency of provinces in using resources. METHODS The data for 2001 and 200...

Abstract The objective of this study was to investigate a simple and less expensive process for the removal sulfate from Iranian Chemical Industries Investment Company' wastewater using ettringite (a calcium aluminum (Ca 6 Al 2 (SO 4 ) 3 (OH) 12 .26H O)) precipitation process. optimum experimental conditions Al(OH) recovery were determined batch experiments. Using Ca(OH) allowed achieve pH (pH ...