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Because inorganic scales reduce permeability near wellbores, they cause an additional pressure drop in this region (skin damage) and reduce production. NaCl precipitation, particularly in gas-producing wells, is one of the formation damage problems which impair the permeability. The use of backwashing water not only requires a large quantity of water, but is also inefficient. This study examined the effect of the ultrasonic waves in NaCl scale removal. Twenty core samples with different permeabilities were saturated with NaCl. After precipitation of NaCl within the cores, the samples were first subjected to water injection and then to water injection with ultrasonic wave radiation. At each stage, the permeability of cores was measured and recorded. Experimental results reveal that applying ultrasonic waves restores the permeability of cores more than water injection alone. In samples with permeability lower than 20, 30-100, 100-700 md and cores with permeabilities higher than 1000 md, ultrasonic waves recover permeability to 80, 42, 87 and 81%, respectively. In contrast, water injection alone improves permeability to 29, 18.5, 62 and 77%, respectively. The effect of these waves is much more obvious than water injection alone in low-permeability cores. SEM images from cores show that ultrasonic waves destroy the structure of deposits of sodium chloride. This phenomenon is due to propagation of these waves and the resulting temperature increase in the surroundings, which leads to the increased solubility of these scales. After exposure to ultrasonic waves, sodium chloride deposits inside the induced fractures of cores could be removed from the fracture, whereas water injection alone could not wash and remove the deposits from the fracture. According to the results of this paper, ultrasonic waves can be used as a novel and efficient technology in gas wells to remove inorganic scales in the near-wellbore region. [ABSTRACT FROM AUTHOR]

The cost-effective production of liquid biofuels from microalgae is limited by several factors such as recovery of the lipid fractions as well as nutrients management. Flash hydrolysis, a rapid hydrothermal process, has been successfully applied to fractionate the microalgal biomass into solid biofuels intermediates while recovering a large amount of the nutrients in the aqueous phase (hydrolyzate) in a continuous flow reactor. The aim of the work is to enhance the quality of a high-ash containing marine algae Nannochloropsis gaditana as biofuel feedstock while recycling nutrients directly for algae cultivation. Characterization of products demonstrated an increase in extractable lipids from 33.5 to 65.5 wt % (dry basis) while retaining the same fatty acid methyl ester profile, in addition to diminution of more than 70 wt % of ash compared to raw microalgae. Moreover, the hydrolyzate was directly used to grow a microalga of the same genus. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1494-1502, 2017 [ABSTRACT FROM AUTHOR]

Power consumption of digital systems is an important issue in nanoscale technologies and growth of process variation makes the problem more challenging. In this brief, we have analyzed the latency, energy consumption, and effects of process variation on different structures with respect to the design structure and logic depth to propose architectures with higher throughput, lower energy consumption, and smaller performance loss caused by process variation in application-specific integrated circuit design. We have exploited adders as different implementations of a processing unit, and propose architectural guidelines for finer technologies in subthreshold which are applicable to any other architecture. The results show that smaller computing building blocks have better energy efficiency and less performance degradation because of variation effects. In contrast, their computation throughput will be mid or less unless proper solutions, such as pipelined or parallel structures, are used. Therefore, our proposed solution to improve the throughput loss while reducing sensitivity to process variations is using simpler elements in deep pipelined designs or massively parallel structures. [ABSTRACT FROM PUBLISHER]