Literature survey

About: Literature survey is a research topic. Over the lifetime, 15372 publications have been published within this topic receiving 459196 citations.

Pumped Thermal Electricity Storage: A technology overview

Abstract: A large penetration of variable intermittent renewable energy sources into the electric grid is stressing the need of installing large-scale Energy Storage units. Pumped Hydro Storage, Compressed Air Energy Storage and Flow Batteries are the commercially available large-scale energy storage technologies. However, these technologies suffer of geographical constrains (such as Pumped Hydro Storage and Compressed Air Energy Storage), require fossil fuel streams (like Compressed Air Energy Storage) or are characterised by low cycle life (Flow Batteries). For this reason, there is the need of developing new large-scale Energy Storage Technologies which do not suffer of the above-mentioned drawbacks. Among the in-developing large-scale Energy Storage Technologies, Pumped Thermal Electricity Storage or Pumped Heat Energy Storage is the most promising one due to its long cycle life, no geographical limitations, no need of fossil fuel streams and capability of being integrated into conventional fossil-fuelled power plants. Based on these evidences, in the present work, a literature survey on the Pumped Thermal Electricity Storage technology is presented with the aim of analysing its actual configurations and state of development.

Female post-reproductive lifespan: a general mammalian trait

Abstract: Traditional explanations for the evolution of menopause and post-reproductive lifespan in human females have been based on the benefits of maternal or grand-maternal care outweighing the cost of lost reproduction. These explanations assume an evolutionary origin of menopause since human divergence with the most recent common ancestor. In this study, I conduct a literature survey of studies of 42 mammal species from eight orders, showing that post-reproductive lifespan appears to be widespread among mammals. I then propose an alternative to traditional hypotheses: following accepted theories of trade-offs and senescence, I suggest that the cost of extending reproductive lifespan might be relatively high in female mammals. Somatic and reproductive senescence appear to follow separate trajectories, so it is not surprising that the two processes should occur on different schedules. The timing of each process is probably determined by maximization of reproductive performance and survival early in adulthood, with consequent trajectories resulting in a post-reproductive lifespan. The early end of reproduction relative to lifespan may be due to the cost of production and/or maintenance of oocytes, which decline exponentially over time. Oocyte number below a threshold may trigger an end to normal hormonal cycling.

Heat transfer augmentation using twisted tape inserts: A review

Abstract: Heat transfer enhancement is an important matter of concern for energy conservation and also beneficial from economic point of view. The use of passive devices like twisted tapes, roughness elements, wires inserts etc. are effective methods of heat transfer augmentation. Many research studies on different types of twisted tapes geometries to increase heat transfer rate have been carried out. Also, several correlations were developed to determine heat transfer and friction factor for twisted tape inserts. In the present study, a review on work done in the area of heat transfer augmentation using twisted tapes has been carried out. Previous experimental and numerical studies on various types of twisted tapes (based on the literature survey) were discussed. These studies reveal that the future research in the area of twisted tapes will bring more development in the heat exchanger systems. The optimum shape for twisted tapes can also be developed based on maximisation of heat transfer and minimisation of friction factor regarding fluid used in the system.

An overview of event extraction from text

Abstract: One common application of text mining is event extraction, which encompasses deducing specific knowledge concerning incidents referred to in texts. Event extraction can be applied to various types of written text, e.g., (online) news messages, blogs, and manuscripts. This literature survey reviews text mining techniques that are employed for various event extraction purposes. It provides general guidelines on how to choose a particular event extraction technique depending on the user, the available content, and the scenario of use.

A review of recent developments and technological advancements of variable-air-volume (VAV) air-conditioning systems

Abstract: This study reviewed VAV systems modeling and simulations, control strategies and optimization tools, the airflow characteristics of VAV systems, some common VAV systems׳ faults, detection and diagnosis, energy usage and analysis, and the current applications of variable air volume (VAV) air-conditioning systems. VAV system modeling is very complex as it involves complex structures and parameters a result of which has led to lack of models that combine both the AHU and building with all the required parameters. The most common controllers used in VAV systems are the PID controllers. We saw that supply air temperature and the flow rate of supply air are the best parameters that can be optimized in a VAV system as they greatly minimize energy consumption. Genetic algorithms have good robustness, and can be easily parallelized. However, they suffer from shortcomings such as slow convergence rates under some conditions, and have difficulty in adjustment of algorithms since there are no rules for determining the number of individuals in populations. FLCs boost of advantages such as less or minimum overshoot, oscillation and power consumption compared to conventional PID controllers, can be used in MIMO systems, and they do not require models as they can control non-linear processes. Airflow control in VAV systems can be achieved through controlling static pressure and position of the damper. Literature survey shows that balancing and distribution of airflow in VAV air-conditioning systems can be considered to be one of the main challenging areas of research concerning VAV system control. Most methods used today for detecting and diagnosing faults are hybrid. These are superior to the conventional methods of FDD. In conclusion, VAV air-conditioning systems are the most energy efficient systems in use today. Despite of their current strengths, VAV systems energy saving potential can still be improved.