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A quality management system (QMS) is defined as interacting activities, methods and procedures used to monitor, control and improve service quality. The purpose of this paper is to describe the QMS status using the Quality Management System Index (QMSI) in hospitals affiliated to Shahid Beheshti Medical Sciences University in Tehran, Iran.

In this cross-sectional study, 28 hospitals were investigated. A validated 46-item questionnaire was used for data collection. Data were analyzed using descriptive statistics, Pearson correlation, independent student’s t-test and regression analysis.

The mean QMSI score was 18.4: 15.3 for public and 20.9 for non-public hospitals (p=0.001). The lowest (1.96) and the highest (2.14) scores related to “Quality policy documents” and “Quality monitoring by the board,” respectively. The difference between public and non-public hospitals was significant in all nine QMSI dimensions (p=0.001). The QMSI score was higher in non-public and small hospitals than in public and large ones (p=0.05).

Most QMS studies come from developed countries, and there is no systematic information about the mechanisms and processes involved in implementing QMS in developing countries like Iran. This is the first study on Iranian hospital QMS using a newly developed tool (QMSI), and results showed that QMS maturity in these hospitals was relatively good, but the non-public hospitals status (private and charity) was far better than public hospitals.

Because of its increased absorptance in fluid and reduced heat loss, direct absorption nanofluid (DANF) is receiving intense interest as an efficient way to harvest solar energy. This work aims to investigate, for the first time, the application of DANF in parabolic trough collectors (PTC), a promising collector for solar thermal systems.

A representative flow and heat transfer study of different fluids in a straight tube is conducted, and the basic energy equation and radiative transfer equations are numerically solved to obtain the fluid temperature distribution and energy conversion efficiency. Ethylene glycol (EG) and different concentrations of (i.e., 0.1-0.6 per cent) multi-wall carbon nanotubes (MWCNT) in EG are used as sample fluids. Four cases are studied for a traditional PTC (i.e., using metal tube) and a direct absorption PTC (i.e., using transparent tube) including a bare tube, a tube with an air-filled glass envelope and a tube with vacuumed glass envelop. The numerical results are verified by an experimental study using a copper-glass absorber tube, which reveals the good potential of DANFs.

Compared with a conventional PTC, using DANF shows an increase of 8.6 per cent and 6.5 K, respectively, in thermal efficiency and outlet temperature difference at a volume fraction (0.5 per cent) of nanoparticles. The results also show that the improvement in solar efficiency increases with increasing particle concentrations, and the vacuum insulated case has the highest efficiency.

In all previous studies, an important section was missing as the effect of photons on the direct solar absorption trough collector, which is considered in this study. This paper proposes a new concept of using direct solar absorption nanofluids for concentrated solar collectors and analyzes the performance of both absorptance and transmittance efficiency considerations. To reveal the potential of the new concept, an analytical model based on energy balance is developed, and two case studies are performed.