term performance
Recently Published Documents

The development of turbulence after transcatheter aortic valve (TAV) implantation may have detrimental effects on the long-term performance and durability of the valves. The characterization of turbulent flow generated after TAV implantation can provide fundamental insights to enhance implantation techniques. A self-expandable TAV was tested in a pulse replicator and the three-dimensional flow field was extracted by means of tomographic particle image velocimetry. The valve was fixed inside a silicone phantom mimicking the aortic root and the flow field was studied for two different supra-annular axial positions at peak systole. Fluctuating velocities and turbulent kinetic energy were compared between the two implantations. Velocity spectra were derived at different spatial positions in the turbulent wakes to characterize the turbulent flow. The valve presented similar overall flow topology but approximately 8% higher turbulent intensity in the lower implantation. In this configuration, axial views of the valve revealed smaller opening area and more corrugated leaflets during systole, as well as more accentuated pinwheeling during diastole. The difference arose from a lower degree of expansion of the TAV's stent inside the aortic lumen. These results suggest that the degree of expansion of the TAV in-situ is related to the onset of turbulence and that a smaller and less regular opening area might introduce flow instabilities that could be detrimental for the long-term performance of the valve. The present study highlights how implantation mismatches may affect the structure and intensity of the turbulent flow in the aortic root.

Utilizing a deep Borehole Heat Exchanger (BHE) has been recognized as a clean, renewable, low-carbon-emission, and sustainable way for heating of residential buildings and greenhouses. In this study, the long-term performance of horizontal deep BHE in intermittent mode is scrutinized. In this regard, to predict the transient heat transfer process in the deep BHEs, a mathematical model is developed and then verified by using the experimental results. The effect various key parameters including flow rate of circulating fluid, undisturbed ground temperature, inlet fluid temperature, and ground thermal conductivity on the thermal performance of deep BHE in continuous and intermittent mode is studied. According to the results, increasing the flow rate of circulating fluid, undisturbed ground temperature, and ground thermal conductivity is favorable for heat extraction rate. Moreover, the effect of three specific parameters for intermittent operation including periodic time interval, flow rate ratio, and recovery period ratio on the long-term performance of horizontal deep BHE are scrutinized. Based on the results, by decreasing the periodic time interval and increasing the flow rate ratio, the mean heat extraction rate in the period of 30 years is increased and the mean borehole’s wall temperature is decreased. Furthermore, by increasing the recovery period ratio, the heat extraction rate increases significantly while the total extracted energy decreases.

Recent issues toward ultrathin soft electronics are gradually focused on effective detection under complex environments. The promising strategies for long-term performance are summarized as a roadmap for design and fabrication.

This edition reviews the long-term performance of economic growth and productivity in the region. It then draws on research from the Inter-American Development Banks Connectivity, Markets, and Finance Division that estimates how much investment in digital infrastructure is needed for countries across Latin America and the Caribbean to reach the levels of advanced economies. This research also estimates both the potential economic benefits associated with that investment and its costs, highlighting the potentially large multipliers associated with closing digital infrastructure gaps. The highlights of the analysis are as follows. It is estimated that closing the digital access gap between Caribbean economies and members countries of the Organization for Economic Co-operation and Development (OECD) could potentially increase the regions GDP by about 6 to 12 percent over the medium term, depending on the country. These gains are multiples of the estimated costs, ranging from about 2 times to nearly 50 times those estimated costs. Productivity gains represent about 80 percent of the estimated improvements in GDP. As is typical with the Caribbean Quarterly Bulletin, the Regional Overview is followed by country sections that provide more detailed analysis for each of the countries covered.