Understanding the Relationship Between Shrinking Cities and Land Prices:Spatial Pattern,Effectiveness,and Policy Implications

Urban shrinkage has emerged as a widespread phenomenon globally and has a significant impact on land,particularly in terms of land use and price.This study focuses on 2851 county-level cities in China in 2005–2018(excluding Hong Kong,Macao,Taiwan,and‘no data’areas in Qinhai-Tibet Plateau)as the fundamental units of analysis.By employing nighttime light(NTL)data to identify shrinking cities,the propensity score matching(PSM)model was used to quantitatively examine the impact of shrinking cities on land prices,and evaluate the magnitude of this influence.The findings demonstrate the following:1)there were 613 shrinking cities in China,with moderate shrinkage being the most prevalent and severe shrinkage being the least.2)Regional disparities are evident in the spatial distribution of shrinking cities,especially in areas with diverse terrain.3)The spatial pattern of land price exhibits a significant correlated to the economic and administrative levels.4)Shrinking cities significantly negatively impact on the overall land price(ATT=–0.1241,P<0.05).However,the extent of the effect varies significantly among different spatial regions.This study contributes novel insights into the investigation of land prices and shrinking cities,ultimately serving as a foundation for government efforts to promote the sustainable development of urban areas.

Implications for brainstem recovery from studies in primates after sensory loss from arm

For decades,researchers have known that when neurons lose their activating inputs,they can atrophy and even die.For example,removing sensory nerve inputs from the arm to the spinal cord after amputation or cutting the spinal nerves can shrink the post-synaptic target zones(e.g.,Woods et al.,2000).From touch receptors for the hand and arm,primary nerve afferents enter the spinal cord,and axons travel in the dorsal columns to target the cuneate nucleus(Cu)of the brainstem on the same side of the body(Figure 1).When sensory loss is unilateral,the overwhelming result is for the associated primary target zone to shrink in total size(cross-sectional area),as compared to the size of the opposite side.

Exact solutions for magnetohydrodynamic nanofluids flow and heat transfer over a permeable axisymmetric radially stretching/shrinking sheet

We report on the magnetohydrodynamic impact on the axisymmetric flow of Al_(2)O_(3)/Cu nanoparticles suspended in H_(2)O past a stretched/shrinked sheet.With the use of partial differential equations and the corresponding thermophysical characteristics of nanoparticles,the physical flow process is illustrated.The resultant nonlinear system of partial differential equations is converted into a system of ordinary differential equations using the suitable similarity transformations.The transformed differential equations are solved analytically.Impacts of the magnetic parameter,solid volume fraction and stretching/shrinking parameter on momentum and temperature distribution have been analyzed and interpreted graphically.The skin friction and Nusselt number were also evaluated.In addition,existence of dual solution was deduced for the shrinking sheet and unique solution for the stretching one.Further,Al_(2)O_(3)/H_(2)O nanofluid flow has better thermal conductivity on comparing with Cu/H_(2)O nanofluid.Furthermore,it was found that the first solutions of the stream are stable and physically realizable,whereas those of the second ones are unstable.

Insight into the dynamics of non-Newtonian Carreau fluid when viscous dissipation,entropy generation,convective heating and diffusion are significant

The investigation endorsed the convective flow of Carreau nanofluid over a stretched surface in presence of entropy generation optimization.The novel dynamic of viscous dissipation is utilized to analyze the thermal mechanism of magnetized flow.The convective boundary assumptions are directed in order to examine the heat and mass transportation of nanofluid.The thermal concept of thermophoresis and Brownian movements has been re-called with the help of Buongiorno model.The problem formulated in dimensionless form is solved by NDSolve MATHEMATICA.The graphical analysis for parameters governed by the problem is performed with physical applications.The affiliation of entropy generation and Bejan number for different parameters is inspected in detail.The numerical data for illustrating skin friction,heat and mass transfer rate is also reported.The motion of the fluid is highest for the viscosity ratio parameter.The temperature of the fluid rises via thermal Biot number.Entropy generation rises for greater Brinkman number and diffusion parameter.

Navigation Finsler metrics on a gradient Ricci soliton

In this paper,we study a class of Finsler metrics defined by a vector field on a gradient Ricci soliton.We obtain a necessary and sufficient condition for these Finsler metrics on a compact gradient Ricci soliton to be of isotropic S-curvature by establishing a new integral inequality.Then we determine the Ricci curvature of navigation Finsler metrics of isotropic S-curvature on a gradient Ricci soliton generalizing result only known in the case when such soliton is of Einstein type.As its application,we obtain the Ricci curvature of all navigation Finsler metrics of isotropic S-curvature on Gaussian shrinking soliton.

Mass transfer process of peanut protein extracted by bis(2-ethylhexyl)sodium sulfosuccinate reverse micelles

The liquid-liquid extraction method using reverse micelles can simultaneously extract lipid and protein of oilseeds,which have become increasingly popular in recent years.However,there are few studies on mass transfer processes and models,which are helpful to better control the extraction process of oils and proteins.In this paper,mass transfer process of peanut protein extracted by bis(2-ethylhexyl)sodium sulfosuccinate(AOT)/isooctane reverse micelles was investigated.The effects of stirring speed(0,70,140,and 210 r/min),temperature of extraction(30,35,40,45,and 50℃),peanut flour particle size(0.355,0.450,0.600,and 0.900 mm)and solidliquid ratio(0.010,0.0125,0.015,0.0175,and 0.020 g/mL)on extraction rate were examined.The results showed that extraction rate increased with temperature rising,particle size reduction as well as solid-liquid ratio increase respectively,while little effect of stirring speed(P>0.05)was observed.The apparent activation energy of extraction process was calculated as 10.02 kJ/mol and Arrhenius constant(A)was 1.91 by Arrhenius equation.There was a linear relationship between reaction rate constant and the square of the inverse of initial particle radius(1/r_(0)^(2))(P<0.05).This phenomenon and this shrinking core model were anastomosed.In brief,the extraction process was controlled by the diffusion of protein from the virgin zone interface of particle through the reacted zone and it was in line with the first order reaction.Mass transfer kinetics of peanut protein extracted by reverse micelles was established and it was verified by experimental results.The results provide an important theoretical guidance for industrial production of peanut protein separation and purification.

A new model of flow over stretching(shrinking)and porous sheet with its numerical solutions

The viscous fluid flow and heat transfer over a stretching(shrinking)and porous sheets of nonuniform thickness are investigated in this paper.The modeled problem is presented by utilizing the stretching(shrinking)and porous velocities and variable thickness of the sheet and they are combined in a relation.Consequently,the new problem reproduces the different available forms of flow motion and heat transfer maintained over a stretching(shrinking)and porous sheet of variable thickness in one go.As a result,the governing equations are embedded in several parameters which can be transformed into classical cases of stretched(shrunk)flows over porous sheets.A set of general,unusual and new variables is formed to simplify the governing partial differential equations and boundary conditions.The final equations are compared with the classical models to get the validity of the current simulations and they are exactly matched with each other for different choices of parameters of the current problem when their values are properly adjusted and manipulated.Moreover,we have recovered the classical results for special and appropriate values of the parameters(δ_(1),δ_(2),δ_(3),c,and B).The individual and combined effects of all inputs from the boundary are seen on flow and heat transfer properties with the help of a numerical method and the results are compared with classical solutions in special cases.It is noteworthy that the problem describes and enhances the behavior of all field quantities in view of the governing parameters.Numerical result shows that the dual solutions can be found for different possible values of the shrinking parameter.A stability analysis is accomplished and apprehended in order to establish a criterion for the determinations of linearly stable and physically compatible solutions.The significant features and diversity of the modeled equations are scrutinized by recovering the previous problems of fluid flow and heat transfer from a uniformly heated sheet of variable(uniform)thickness with variable(uniform)stretching/shrinking and injection/suction velocities.

Chemically Radiative MHD Flow of a Micropolar Nanofluid over a Stretching/ Shrinking Sheet with a Heat Source or Sink

This study examines the behavior of a micropolar nanofluidflowing over a sheet in the presence of a transverse magneticfield and thermal effects.In addition,chemical(first-order homogeneous)reactions are taken into account.A similarity transformation is used to reduce the system of governing coupled non-linear partial differ-ential equations(PDEs),which account for the transport of mass,momentum,angular momentum,energy and species,to a set of non-linear ordinary differential equations(ODEs).The Runge-Kutta method along with shoot-ing method is used to solve them.The impact of several parameters is evaluated.It is shown that the micro-rota-tional velocity of thefluid rises with the micropolar factor.Moreover,the radiation parameter can have a remarkable influence on theflow and temperature profiles and on the angular momentum distribution.

Mixed convectional and chemical reactive flow of nanofluid with slanted MHD on moving permeable stretching/shrinking sheet through nonlinear radiation,energy omission

Hybrid nanofluids are remarkable functioning liquids that are intended to reduce the energy loss while maximizing the heat transmission.In the involvement of suction and nonlinear thermal radiation effects,this study attempted to explore the energy transmission features of the inclined magnetohydrodynamic(MHD)stagnation flow of CNTs-hybrid nanofluid across the nonlinear permeable stretching or shrinking sheet.This work also included some noteworthy features like chemical reactions,variable molecular diffusivity,quadratic convection,viscous dissipation,velocity slip and heat omission assessment.Employing appropriate similarity components,the model equations were modified to ODEs and computed by using the HAM technique.The impact of various relevant flow characteristics on movement,heat and concentration profiles was investigated and plotted on a graph.Considering various model factors,the significance of drag friction,heat and mass transfer rate were also computed in tabular and graphical form.This leads to the conclusion that such factors have a considerable impact on the dynamics of fluid as well as other engineering measurements of interest.Furthermore,viscous forces are dominated by increasing the values ofλ_(p),δ_(m)andδ_(q),and as a result,F(ξ)accelerates while the opposite trend is observed for M andφ.The drag friction is boosted by the augmentation M,λ_(p)andφ,but the rate of heat transfer declined.According to our findings,hybrid nanoliquid effects dominate that of ordinary nanofluid in terms of F(ξ),Θ(ξ)andφ(ξ)profiles.The HAM and the numerical technique(shooting method)were found to be in good agreement.

Leaching kinetics of low-grade copper ore containing calcium-magnesium carbonate in ammonia-ammonium sulfate solution with persulfate

The leaching kinetics of copper from low-grade copper ore was investigated in ammonia-ammonium sulfate solution with sodium persulfate. The effect parameters of stirring speed, temperature, particle size, concentrations of ammonia, ammonium sulfate and sodium persulfate were determined. The results show that the leaching rate is nearly independent of agitation above 300 r/min and increases with the increase of temperature, concentrations of ammonia, ammonium sulfate and sodium persulfate. The EDS analysis and phase quantitative analysis of the residues indicate that bornite can be dissolved by persulfate oxidization. The leaching kinetics with activation energy of 22.91 kJ/mol was analyzed by using a new shrinking core model （SCM） in which both the interfacial transfer and diffusion across the product layer affect the leaching rate. A semi-empirical rate equation was obtained to describe the leaching process and the empirical reaction orders with respect to the concentrations of ammonia, ammonium sulfate and sodium persulfate are 0.5, 1.2 and 0.5, respectively.

Kinetic model for calcium sulfate decomposition at high temperature

A modified shrinking unreacted-core model,based on thermogravimetric analysis,was developed to investigate CaSO4 decomposition in oxy-fuel combustion,especially under isothermal condition which is difficult to achieve in actual experiments due to high-temperature corrosion.A method was proposed to calculate the reaction rate constant for CaSO4 decomposition.Meanwhile,the diffusion of SO2 and O2,and the sintering of CaO were fully considered during the development of model.The results indicate that the model can precisely predict the decomposition of CaSO4 under high SO2 concentration（1100×10-6）.Concentrations of SO2 and O2 on the unreacted-core surface were found to increase first and then decrease with increasing temperature,and the average specific surface area and porosity of each CaO sintering layer decreased with increasing time.The increase of SO2 and/or O2 concentration inhibited CaSO4 decomposition.Moreover,the kinetics of CaSO4 decomposition had obvious dependence on temperature and the decomposition rate can be dramatically accelerated with increasing temperature.

空空导弹导引头小波降噪参数优选仿真研究

在对空空导弹导引头含噪信号实施小波阈值降噪时,以提高信噪比为规则,优选了降噪参数,并进行了离线降噪处理和实时降噪处理两种模式的仿真实验。在离线降噪模式下,通过对降噪参数的选择优化,从强噪声背景中得到了与实际的视线角速度高度一致的有用信号。在实时降噪模式下,考虑到算法的复杂性要求对降噪参数的限制,有针对性地选取了计算比较简单的降噪参数,降噪后提高信噪比仍能达到5 dB以上。研究表明,利用小波降噪技术能够克服传统导引头降噪技术的固有缺陷,可以为导引头滤波器的设计与实现提供支持。

基于小波变换的图像去噪方法

针对图像中存在的高斯噪声、椒盐噪声和二者混合噪声,提出了一种基于小波变换的图像去噪方法。为进一步提高图像去噪质量,采用Bayes Shrink和中值滤波相结合的方法,对其的不同去噪顺序进行实验,并与中值滤波、Bayes Shrink方法相比较。实验结果表明,先进行Bayes Shrink再进行中值滤波的方法要优于其他方法,去噪效果较好。在图像去噪处理中该种方法具有实际应用价值。

加快SMO算法训练速度的策略研究

SMO(序贯最小优化算法)算法是目前解决支持向量机训练问题的一种十分有效的方法,但是当面对大样本数据时,SMO训练速度比较慢。考虑到在SVM的优化过程中并不是所有样本都能影响优化进展,提出了两种删除样本的策略:一种是基于距离,一种是基于拉格朗日乘子的值。在几个著名的数据集的试验结果表明,两种策略都可以大大缩短SMO的训练时间,特别适用于大样本数据。

基于非下采样Contourlet变换的图像自适应阈值去噪算法

利用非下采样Contourlet变换的平移不变性和多方向选择性,考虑非下采样Contourlet变换域内相邻尺度间和同一尺度、不同方向间图像系数和噪声系数之间不同的相关性,根据子带含有信息量的多少,自适应地调节BayesShrink阈值大小,不仅使弱的边缘细节被从噪声中提选了出来,而且避免了将较大的噪声系数判定为图像细节的错误.实验结果表明,该算法克服了恢复图像中的伪Gibbs失真,实现了信号和噪声的有效分离,在去除噪声的同时尽可能多地保留了图像的边缘细节,提高了恢复图像的PSNR值.

Preparation of bismuth subcarbonate by liquid ball-milling transformation method from bismuth oxide

In order to solve the problems of environment pollution and high cost in traditional process of bismuth subcarbonate preparation, a new process using ball-milling transformation method from NH4HCO3 and Bi2O3 was proposed. Additionally, the kinetics of bismuth subcarbonate preparation was studied. Effects of reaction temperature, particle size of bismuth oxide, solid-to-liquid ratio and concentrations of ammonium bicarbonate on the conversion rate of bismuth oxide were studied. The results indicate that the conversion rate of bismuth oxide significantly increased under the conditions of higher temperature, smaller particle size, higher concentration of ammonium bicarbonate and smaller solid-to-liquid ratio. The XRD and ICP-AES analyses show that the purity of product is high. The reaction kinetics with activation energy of 9.783 kJ/mol was analyzed by shrinking core model, and the whole transformation process is controlled by solid product layer diffusion. A semi-empirical kinetics equation was obtained to describe the conversion process.

List流上梯度Shrinking Solitons的广义Ricci张量

研究List流上梯度Shrinking Solitons的广义Ricci张量和广义数量曲率的增长行为.通过选取适当的截断函数,利用散度定理,得到了广义Ricci张量的积分上界估计.另外,还得到了广义数量曲率的积分上界估计.

新的多位self-shrinking序列的构造

给出了一种多位自收缩序列,并解决了多位自收缩序列的周期下界,线性复杂度,最后构造了新的多位self-shrinking序列模型.

基于多小波—非采样Contourlet变换的自适应阈值图像去噪方法

为抑制Contourlet变换的非平移不变性和冗余性给图像去噪所带来的图像失真等缺陷,提出一种新的基于多小波—非采样Contourlet变换和基于BayesShrink的自适应阈值去噪算法:首先利用多小波对图像进行多尺度分解并结合非下采样方向滤波器组进行方向分解,接着根据分解所得到的各方向子带的关系,改进了BayesShrink自适应阈值取值方法,对图像进行去噪处理。实验结果表明:该算法去噪后图像的信噪比(SNR)与已有算法相比,有了明显的提高,有效地抑制了原Contourlet变换所造成的伪Gibbs现象,更好地保留了图像的细节信息。

基于改进邻域收缩法的非下采样Contourlet变换域红外图像去噪

提出了一种基于改进邻域收缩法的NSCT域红外图像去噪算法。首先使用Bayes Shrink自适应阈值取代通用阈值作为改进邻域收缩法中的收缩阈值,再利用该收缩阈值对NSCT分解后的红外图像的高频子带进行系数收缩处理。仿真实验结果表明:改进算法在去噪性能和视觉效果方面相对于实验中的对比方法均有所提高,具有较好的抗噪性能和良好的边缘保护能力,能够有效的用于红外图像的去噪中。