Control of global variables for identical and non-identical Josephson junctions arrays

In the paper a way to solve an LQ-problem for a Josephson junction array with a common LRC-load is proposed. The cases of identical and non-identical Josephson junctions are considered. The solution ensures phase stabilization of Josephson current in every junction. The results are obtained using computer simulation in Jupyter Notebook and MATLAB.

Housing prices in emerging countries during COVID-19: evidence from Turkey

Purpose By considering the rapid and continuous increase of housing prices in Turkey recently, this study aims to examine the determinants of the residential property price index (RPPI). In this context, a total of 12 explanatory (3 macroeconomic, 8 markets and 1 pandemic) variables are included in the analysis. Moreover, the residential property price index for new dwellings (NRPPI) and the residential property price index for old dwellings (ORPPI) are considered for robustness checks. Design/methodology/approach A quantile regression (QR) model is used to examine the main determinants of RPPI in Turkey. A monthly time series data set for the period between January 2010 and October 2020 is included. Moreover, NRPPI and ORPPI are examined for robustness. Findings Predictions for RPPI, NRPPI and ORPPI are carried out separately at the country (Turkey) level. The results show that market variables are more important than macroeconomic variables; the pandemic and rent have the highest effect on the indices; The effects of the explanatory variables on housing prices do not change much from low to high levels, the COVID-19 pandemic and weighted average cost of funding have a decreasing effect on indices while other variables have an increasing effect in low quantiles; the pandemic and monetary policy indicators have a negative and significant effect in low quantiles whereas they are not effective in high quantiles; the results for RPPI, NRPPI and ORPPI are consistent and robust. Research limitations/implications The results of the study emphasize the importance of the pandemic, rent, monetary policy indicators and interest rates on the indices, respectively. On the other hand, focusing solely on Turkey and excluding global variables is the main limitation of this study. Therefore, the authors encourage researchers to work on other emerging countries by considering global variables. Hence, future studies may extend this study. Practical implications The COVID-19 pandemic and market variables are determined as influential variables on housing prices in Turkey whereas macroeconomic variables are not effective, which does not mean that macroeconomic variables can be fully ignored. Hence, the main priority should be on focusing on market variables by also considering the development in macroeconomic variables. Social implications Emerging countries can make housing prices stable and affordable, which will increase homeownership. Hence, they can benefit from stability in housing markets. Originality/value The QR method is performed for the first time to examine housing prices in Turkey at the country level according to the existing literature. The results obtained from the QR analysis and policy implications can also be used by other emerging countries that would like to increase homeownership to provide better living conditions to citizens by making housing prices stable and keeping them under control. Hence, countries can control housing prices and stimulate housing affordability for citizens.

Numerical Modeling of Centrifugal Compressors With Heterogeneous Incoming Flow due to Low Pressure Exhaust Gas Recirculation

Low pressure EGR (LP-EGR) has become recently one of the most investigated technique in the field of internal combustion engines. When LP-EGR is active, two streams with different psychrometric conditions are mixed at the compressor inlet, i.e. fresh air (considered as cold and dry) and EGR (humid and warm). The main objective of the present work is to assess the impact of the inlet flow heterogeneity, associated with LP-EGR systems, in the performance of centrifugal compressor using 3D CFD simulations. Two intake configurations will be studied, namely a standard straight duct providing the compressor with a homogeneous flow and T junction with a mixing of air and EGR streams. 9 operating points using an EGR rate of 15% (or equivalent inlet conditions for the single duct) are explored. The temporal treatment is firstly assessed, comparing steady RANS simulations against unsteady ones for both intakes, discussing their behavior in terms of global variables and in mean flow field too. These studies show how the steady approach is not enough accurate for predicting the heterogeneity of the flow field in LP-EGR applications. After that, the comparison in global variables between the T-junction inlet and the standard inlet shows slightly differences in terms of compression ratio (around 0.5%) and isentropic efficiency (around 1%). However, in terms of local differences, the case with the standard inlet is clearly not able to predict the temperature heterogeneity of the case with a T-joint. Despite these issues, for an EGR rate of 15%, the global parameters of the compressor are not affected by the T-junction when equivalent operating points are considered in a single duct intake, so this approach can be employed to still use the standard compressor map for LP-EGR applications.