Effect of Magnetic Field on Entropy Generation in a Microchannel Heat Sink with Offset Fan Shaped

In this study, convection flow in microchannel heat sink with offset fan-shaped reentrant cavities in sidewall filled with Fe3O4-water is numerically investigated. The effects of changing some parameters such as Reynolds number and magnetic field are considered. The nanofluid flow is laminar, steady and incompressible, while the thermo-physical properties of nanoparticles were assumed constant. A finite volume method and two phase mixture models were used to simulate the flow. The obtained results show that the frictional entropy generation increases as Reynolds number increases, while a reverse trend is observed for thermal entropy generation. By applying a non-uniform magnetic field, the entropy generation due to heat transfer decreases at first and then increases. When using the uniform magnetic field, the frictional entropy generation and thermal entropy generation is negligible. For all studied cases, the total entropy generation decreases using non-uniform magnetic fields. The results indicate that by increasing the magnetic field power, the total entropy generation decreases

Essays on the impact of different forms of collaborative R&D on innovation and technological change

R&D alliance is a multifaceted phenomenon, in which various socio-technological mechanisms operate in the interaction of partner firms. This dissertation is composed of three studies to shed light on different dimensions of firms’ resources and performance in different forms of R&D collaborations. These studies consider (1) how the partner firms differences with respect to different dimensions of their knowledge bases influence inter-firm learning in dyadic R&D alliances, (2) how the partner firm differences in their resources across locales influence the multi-partner alliance performances at both alliance and firm levels, and (3) how firms leverage R&D collaboration to navigate the dynamics of technology selection during technology change. The findings of these studies tie together to the extent that they clarify the complex dynamics that exist between individual firms and their alliance partners in order to realize individual and joint value. In general, this dissertation contributes to the strategy and technology management literature by elucidating the less-explored dimensions of the firm’s resources and performance in R&D collaborations

Determining the Optimal Type of Non-Smooth Intersection Using Particle Mass Algorithm (PSO)

Nowadays, with increasing number of vehicles, the intersections of the same level are in many problems. There are different ways to solve this problem, which is now converting the intersection of the intersection to the unequal intersection of the engineers' attention. But a model that takes into account different factors of the intersection is not in an optimal level. In this research, we have tried to provide a model for choosing the optimal type of intersecting intersection with consideration of effective factors. The intersections in this study are directional intersections, full cloying, semi-clover, single-point and rhombus simulated using the AIMSUN software. The parameters considered for each intersection are the amount of air pollutants produced, fuel consumption, and travel time. And the value of the above parameters is derived from the outputs of the AIMSUN software, then all of them are converted to cost. Subsequently, using the massive particle algorithm (PSO) in the following of the study was used, and this algorithm is used to calculate traffic volumes of 1000, 3500 and 6500 vehicles per an hour, respectively, in intersections of directional, rhomboid and single-pronged as an intersection, the optimal non-level is presented. Keywords: Non- intersection crosses, Prioritization, Mass Particle Algorithm (PSO) DOI: 10.7176/CER/11-6-03 Publication date:July 31st 201

Structural and energy properties of interstitial molecular hydrogen in single-crystal silicon

The structural and energy characteristics of interstitial molecular hydrogen in single-crystal silicon are theoretically studied. The dependence of the potential energy of the system on the position and orientation of the interstitial defect is investigated, and the mechanism of interaction of a hydrogen molecule with a silicon crystal is considered. A three-dimensional model is employed to calculate the energy spectrum of H2 in Si, and the obtained dispersion law is analyzed

Prevalence of rapidly growing mycobacteria (RGM) in Iran: Systematic review and meta-analysis

AbstractBackgroundThe infections due to rapidly growing mycobacteria (RGM) are becoming an important health problem in many countries in the world. Globally, an increase in RGM infections is being reported from several regions worldwide. However, there is limited information about the prevalence of these kinds of organisms in Iran.MethodsThe relevant data of the prevalence of RGM were retrieved by searching several databases, such as PubMed, Web of Science, Cochrane Library, Embase, Scopus, Iranmedex, and Scientific Information Database. Meta-analysis was performed by Comprehensive Meta-Analysis (V2.0, Biostat) software.ResultsThe meta-analyses showed that the Mycobacterium fortuitum (22.7% [95% CI 16.1–30.9]), Mycobacterium abscessus (14.0% [95% CI 6.4–27.8]) and Mycobacterium chelonae (7.6% [95% CI 2.8–18.8]) were the most prevalent RGM among the conducted studies in Iran.ConclusionsThe relatively high prevalence of RGM underlines the need for greater enforcement of infection control strategies. Establishment of appropriate diagnostic criteria and management guidelines for diseases caused by RGM and expanding the number and quality of regional reference laboratories may facilitate more accurate action for prevention and control of this kind of bacteria

Adaptive Molecule Transmission Rate for Diffusion Based Molecular Communication

In this paper, a simple memory limited transmitter for molecular communication is proposed, in which information is encoded in the diffusion rate of the molecules. Taking advantage of memory, the proposed transmitter reduces the ISI problem by properly adjusting its diffusion rate. The error probability of the proposed scheme is derived and the result is compared with the lower bound on error probability of the optimum transmitter. It is shown that the performance of introduced transmitter is near optimal (under certain simplifications). Simplicity is the key feature of the presented communication system: the transmitter follows a simple rule, the receiver is a simple threshold decoder and only one type of molecule is used to convey the information