Where is the grass greener? A micro-founded model of migration with application to Guangdong

This paper first develops a structural micro-founded model of aggregate net migration flow using matching ideas to study how migrants choose between multiple locations using multiple criteria. Migration should reduce inequality in the criteria. Most migration models either do not handle multiple criteria and locations or lack micro foundation. The model predicts that migration flows will be out of all but the top two ranked regions. The empirical work, which uses 1990-1999 Guangdong annual data, confirms this proposition and finds a high degree of common marginal effects of the criteria among 18 locations but also finds increasing regional inequalities

Research on thrust fl uctuation suppression and control algorithm of permanent magnet linear synchro

Compared with the conventional rotary motor, the permanent magnet linear synchronous motor (PMLSM) has the advantages of simple structure, large thrust and good fast response. However, due to the linear motor ripple disturbance and positioning force changes will cause thrust fl uctuatio ns, but also aff ected by the end eff ect, slotting force and load changes, system parameter drift, nonlinear friction force, etc., resulting in poor system controllability, which directly aff ects the positioning and trajectory tracking accuracy of the linear motor, by observing the thrust fl uctuations of the permanent magnet linear synchronous motor, By using prediction function and fuzzy control algorithm, the thrust fl uctuation suppression method based on fuzzy prediction function control is established, and the improved prediction function fuzzy controller is constructed. According to the deviation and deviation change rate of the system, the parameters of the fuzzy controller are optimized and adjusted online by using the proportional coeffi cient, so as to improve the comprehensive performance of the linear motor servo system, and provide the theoretical basis and technical approach for realizing the high-performance linear motion system

Three dimensional quotient singularity and 4d N=1\mathcal{N}=1 AdS/CFT correspondence

We systematically study the AdS/CFT correspondence induced by D3 branes probing three dimensional Gorenstein quotient singularity $\mathbb{C}^3/G$. The field theory is given by the McKay quiver, which has a vanishing NSVZ beta function assuming that all the chiral fields have the $U(1)_R$ charge $\frac{2}{3}$. Various physical quantities such as quiver Hilbert series, superconformal index, central charges, etc are computed, which match exactly with those computed using the singularity. We also study the relevant deformation of those theories and find the dual geometry, therefore generate many new interesting AdS/CFT pairs. The quiver gauge theory defined using finite subgroups of $SO(3)$ group has some interesting features, for example, its Seiberg duality behavior is quite interesting.Comment: 43 pages, 15 tables, and 13 figure

From hunters to herders. Reflections on the “Ecological Migration” of the Chinese Evenki reindeer herders

Le « mode de vie traditionnel » des Évenks éleveurs de rennes de Chine a connu d’importants changements suite à la « migration écologique » de 2003 et l’interdiction de la chasse. Ainsi, l’identité des Évenks est passée du statut de « chasseurs » à celui d’« éleveurs de rennes ». Dans le passé, la désignation de chasseurs ne renvoyait pas seulement à une identité ethnique, mais également à une identité politique. Par ailleurs, depuis 2009, le gouvernement local tente de revaloriser le mode de vie des Évenks éleveurs de rennes en développant le tourisme. Basé sur une enquête de terrain d’une année menée en 2003-2004 et sur plusieurs visites effectuées entre 2011 et 2014, cet article examine dans un premier temps les diverses politiques gouvernementales conduites chez les Évenks éleveurs de rennes. Il analyse ensuite la situation actuelle des Évenks, les conflits liés aux ressources et les changements d’identités.The “traditional way of life” among the Evenki reindeer herders of China has faced many changes after their “Ecological Migration” in 2003 and the hunting ban. Evenki identity has thus shifted, as they are officially categorised as “reindeer herders” rather than “hunters”. Being identified as a “hunter” meant access to welfare within the government’s institutional arrangement. Furthermore, since 2009, the local government has reconsidered its stance towards the traditional lifestyle of the Evenki and has striven to foster tourism. Based on fieldwork conducted in 2003-2004 and during several visits from 2011 to 2014, this paper first examines various governmental policies aimed at the Evenki. It then analyses the present situation of the Evenki, in particular examining resource conflicts and changing identities

Multi-Physicochemical Modeling of Solid Oxide Fuel Cells and Electrolyzer Cells

Multi-physicochemical models are developed for solid oxide fuel cells and electrolysis cells. The models describe the complicated transport processes of charge (electron/ion) conservation, mass/species conservation, momentum conservation, and energy conservation. Transport processes are coherently coupled with chemical reforming processes, surface elementary reaction processes, as well as electro-oxidation processes of both hydrogen and carbon monoxide. The models are validated with experimental data and utilized for fundamental mechanism studies of SOFCs fueled with different type of fuels, such as hydrogen, hydrocarbon, e.g., methane, H2S, and their mixtures. The fundamental mechanisms associated with syngas generation using electrolysis cell are also extensively investigated using the developed model. The simulation results of SOFCs show that that the Nernst potential EH2 shows a strong correlation with the cell voltage, increasing with increasing the cell voltage. The ECO shows a weak dependence on the cell voltage, especially at the anode/electrolyte interface. Suitable H2S content in CH4 fuel is beneficial to improve the reforming process of CH4 and SOFC electrochemical performance particularly H2-H2O electro-oxidation process. The adsorbed surface species are very sensitive to the variations of the supplied hydrogen and oxygen as well as the cell voltage. To mitigate potential surface carbon deposition, one may: (1) suitably increase H2O content in the fuel; (2) reduce the content of CH4, CO, CO2 in the supplied fuel; (3) increase the operating temperature; (4) increase the cell operating current; (5) improve exchange current density of electrodes. The simulation results of electrolyzer cell indicate that: (1) the intensity of surface electrolysis processes appears to be strong at the H2 electrode/electrolyte interface even though the composite electrode is assumed; (2) the surface electrolysis processes of CO2 and H2O are pretty much independent with each other; (3) the carbon coking effect is mainly determined by the fraction of CO2 in the H2 electrode; (4) high cell voltage conditions may cause the enhancement of the surface coverage of C(s) and the deposition of carbon on the surface of Ni catalyst; (5) high operating temperature may effectively improve adsorption/desorption rate, and enhance surface electrolysis process as well as potentially mitigate carbon deposition on Ni surface

Visualization of POI Category on the Dynamic Rasterized Map Tiles from Geo-Tagged Social Media (Twitter) with SZ-GAT

Spatial zooming graph attention networks (SZ-GAT) is an emerging framework to improve the quality of recommended places visualization on the map. With the advent of location sharing on social networks via mobile devices, the geographic characteristics of the user's points of interest (POIs) contain the visit history, map check-in positions, recommended places, and route plans. In the context of user-preferred POI prediction with map zooming SZ-GAT framework, we propose a visualization for raster category exploration that uses tweet user visit history to represent the POI visit popularity of the raster units. We concentrate on the performance of the POI data visualized map layer zooming process and our results show that the SZ-GAT framework has a better performance of raster category regression with the baselines. Raster category prediction will be used for urban area division, dynamic category feature extraction with user visit history, and government policy-making based on user behaviors of map tiles. This study promotes the progress of deep learning and data mining in the field of human geographic information

Decompiling x86 Deep Neural Network Executables

Due to their widespread use on heterogeneous hardware devices, deep learning (DL) models are compiled into executables by DL compilers to fully leverage low-level hardware primitives. This approach allows DL computations to be undertaken at low cost across a variety of computing platforms, including CPUs, GPUs, and various hardware accelerators. We present BTD (Bin to DNN), a decompiler for deep neural network (DNN) executables. BTD takes DNN executables and outputs full model specifications, including types of DNN operators, network topology, dimensions, and parameters that are (nearly) identical to those of the input models. BTD delivers a practical framework to process DNN executables compiled by different DL compilers and with full optimizations enabled on x86 platforms. It employs learning-based techniques to infer DNN operators, dynamic analysis to reveal network architectures, and symbolic execution to facilitate inferring dimensions and parameters of DNN operators. Our evaluation reveals that BTD enables accurate recovery of full specifications of complex DNNs with millions of parameters (e.g., ResNet). The recovered DNN specifications can be re-compiled into a new DNN executable exhibiting identical behavior to the input executable. We show that BTD can boost two representative attacks, adversarial example generation and knowledge stealing, against DNN executables. We also demonstrate cross-architecture legacy code reuse using BTD, and envision BTD being used for other critical downstream tasks like DNN security hardening and patching.Comment: The extended version of a paper to appear in the Proceedings of the 32nd USENIX Security Symposium, 2023, (USENIX Security '23), 25 page

The Geriatric Nutritional Risk Index Independently Predicts Mortality in Diabetic Foot Ulcers Patients Undergoing Amputations

Objective. Patients with diabetic foot ulcers undergoing amputations have poor prognosis. Malnutrition usually occurs in this population and is associated with increased risk of mortality. The geriatric nutritional risk index (GNRI) is a widely used, simple, and well-established tool to assess nutritional risk. The purpose of this study was to assess the association between GNRI and all-cause mortality in diabetic foot ulcers patients undergoing minor or major amputations. Methods. This was a retrospective cohort study including 271 adult patients. Patients were divided into two groups according to a GNRI cutoff value of 92, and characteristics and mortality were compared between the two groups. Cox proportional hazard analysis was performed to explore the association between GNRI and mortality. Result. GNRI (p<0.001), age (p<0.001), and eGFR (p=0.002) were independent predictors of mortality. Among a subgroup of 230 patients with minor amputation, increased age (p<0.001), coronary artery disease (p=0.030), and increased GNRI (p<0.001) were major risk factors. Conclusion. GNRI on admission might be a novel clinical predictor for the incidence of death in patients with diabetic foot ulcers who were undergoing amputations