Research on the Impact of Market Concern for Real Estate Policy on Housing Prices: Evidence from Internet Search and Hedonic Price Theory

To avoid the effects of systemic financial risks caused by extreme fluctuations in housing price,the Chinese government has been exploring the most effective policies for regulating the housing market.Measuring the effect of real estate regulation policies has been a challenge for present studies.This study innovatively employs big data technology to obtain Internet search data(ISD)and construct market concern index(MCI)of policy,and hedonic price theory to construct hedonic price index(HPI)based on building area,age,ring number,and other hedonic variables.Then,the impact of market concerns for restrictive policy,monetary policy,fiscal policy,security policy,and administrative supervision policy on housing prices is evaluated.Moreover,compared with the common housing price index,the hedonic price index considers the heterogeneity of houses and could better reflect the changes in housing prices caused by market supply and demand.The results indicate that(1)a long-term interaction relationship exists between housing prices and market concerns for policy(MCP);(2)market concerns for restrictive policy and administrative supervision policy effectively restrain rising housing prices while those for monetary and fiscal policy have the opposite effect.The results could serve as a useful reference for governments aiming to stabilize their real estate markets.

Evaluation of the Canadian government policies on controlling the COVID-19 outbreaks

In this paper,we investigate the COVID-19 pandemic in Canada and evaluate the Canadian gov-ernment policies on controlling COVID-19 outbreaks.The first case of COVID-19 was reported in Ontario on 25 January 2020.Since then,there have been over million cases by now.During this time period,the federal,provincial and local governments have implemented regulations and policies in order to control the pandemic.To evaluate these government policies,which may be done by analysing the infection rate,infection period and reproductive number of COVID-19,we approach the problem by introducing an extended susceptible-exposed-infectious-removed(SEIR)model and conduct the model inference by using the iterated filter ensemble adjustment Kalman filter(IF-EAKF)algorithm.We first divide the time period into phases according to the policy intensities in each province by segmenting the time period from 4 March 2020 to 31 Octo-ber 2020 into three time phases:the exploding phase,the strict policy implementation phase,and the provincial reopening phase.We then use IF-EAKF algorithm to obtain the estimates of the model parameters.We show that the infection rate in the second phase is lower than that in both first and third phases.We also discuss the number of new COVID-19 cases under different policy intensities and different policy durations in the third wave of the pandemic.

Hydrodynamic metamaterials:Principles,experiments,and applications

Hydrodynamic metamaterials,a nascent research field,possess immense potential for fluid flow manipulation.With engineered structure design,they offer unparalleled control over fluid behavior beyond the capabilities of conventional methods.In this review,we focus on hydrodynamic metamaterials and provide a comprehensive overview of the current state of this research field.We start by introducing basic theories and principles of hydrodynamic metamaterials and then illustrate the different functions of hydrodynamic metamaterials that have been realized in porous medium flow and Hele‐Shaw flow.Moreover,we also demonstrate the multifunctional metamaterials that have been developed in hydrodynamics.Some research progresses are highlighted due to their promising applications,including drag reduction,microfluidic manipulation,and biological tissue coculture.The review concludes by identifying major challenges and proposing research directions for the future.

Realizing the thinnest hydrodynamic cloak in porous medium flow

Transformation mapping theory offers us great versatility to design invisible cloaks for the physical fields whose propagation equations remain invariant under coordinate transformations.Such cloaks are typically designed as a multi-layer shell with anisotropic material properties,which makes no disturbance to the external field.As a result,an observer outside the cloak cannot detect the existence of this object from the field disturbances,leading to the invisible effect in terms of field prorogation.In fact,for many prorogating fields,at a large enough distance,the field distortion caused by an object is negligible anyway;thus,a thin cloak is desirable to achieve near-field invisibility.However,a thin cloak typically requires more challenging material properties,which are difficult to realize due to the huge variation of anisotropic material parameters in a thin cloak region.For a flow field in a porous medium,by applying the bilayer cloak design method and integrating the inner layer with the obstacle,we successfully reduce the anisotropic multi-layer cloak into an isotropic single-layer cloak.By properly tailoring the permeability of the porous medium,we realize the challenging material parameters required by the ultrathin cloak and build the thinnest shell-shaped cloak of all physical fields up to now.The ratio between the cloak’s thickness and its shielding region is only 0.003.The design of such an ultrathin cloak may help to achieve the near-field invisibility and concealment of objects inside a fluid environment more effectively.