What Causes the Divestment of Multinational Companies in China? A Subsidiary Perspective

This paper examines the causes of MNCs’ divestments in China. The MNCs’ profitability, market shares and productivities are negatively related to the possibility of divestment, while the MNCs’ debts are positively related to the possibility that foreign investments are divested. These results suggest that divestments are affected by MNCs’ performances, and their performances are endogenous shocks for divestment

Modified QML Estimation of Spatial Autoregressive Models with Unknown Heteroskedasticity and Nonnormality

Published in Regional Science and Urban Economics https://doi.org/10.1016/j.regsciurbeco.2015.02.003</p

Get Out of the Valley: Power-Efficient Address Mapping for GPUs

GPU memory systems adopt a multi-dimensional hardware structure to provide the bandwidth necessary to support 100s to 1000s of concurrent threads. On the software side, GPU-compute workloads also use multi-dimensional structures to organize the threads. We observe that these structures can combine unfavorably and create significant resource imbalance in the memory subsystem causing low performance and poor power-efficiency. The key issue is that it is highly application-dependent which memory address bits exhibit high variability. To solve this problem, we first provide an entropy analysis approach tailored for the highly concurrent memory request behavior in GPU-compute workloads. Our window-based entropy metric captures the information content of each address bit of the memory requests that are likely to co-exist in the memory system at runtime. Using this metric, we find that GPU-compute workloads exhibit entropy valleys distributed throughout the lower order address bits. This indicates that efficient GPU-address mapping schemes need to harvest entropy from broad address-bit ranges and concentrate the entropy into the bits used for channel and bank selection in the memory subsystem. This insight leads us to propose the Page Address Entropy (PAE) mapping scheme which concentrates the entropy of the row, channel and bank bits of the input address into the bank and channel bits of the output address. PAE maps straightforwardly to hardware and can be implemented with a tree of XOR-gates. PAE improves performance by 1.31 x and power-efficiency by 1.25 x compared to state-of-the-art permutation-based address mapping

SimpleClick: Interactive Image Segmentation with Simple Vision Transformers

Click-based interactive image segmentation aims at extracting objects with a limited user clicking. A hierarchical backbone is the de-facto architecture for current methods. Recently, the plain, non-hierarchical Vision Transformer (ViT) has emerged as a competitive backbone for dense prediction tasks. This design allows the original ViT to be a foundation model that can be finetuned for downstream tasks without redesigning a hierarchical backbone for pretraining. Although this design is simple and has been proven effective, it has not yet been explored for interactive image segmentation. To fill this gap, we propose SimpleClick, the first interactive segmentation method that leverages a plain backbone. Based on the plain backbone, we introduce a symmetric patch embedding layer that encodes clicks into the backbone with minor modifications to the backbone itself. With the plain backbone pretrained as a masked autoencoder (MAE), SimpleClick achieves state-of-the-art performance. Remarkably, our method achieves 4.15 NoC@90 on SBD, improving 21.8% over the previous best result. Extensive evaluation on medical images demonstrates the generalizability of our method. We further develop an extremely tiny ViT backbone for SimpleClick and provide a detailed computational analysis, highlighting its suitability as a practical annotation tool.Comment: Tech report. Update 03/11/2023: Add results on a tiny model and append supplementary material

Investigation of using limestone calcined clay cement (LC3) in engineered cementitious composites: The effect of propylene fibers and the curing system

Limestone calcined clay cement (LC3) is a new type of low-carbon cement that can reduce energy consumption and carbon dioxide emissions while meeting the performance requirements of ordinary cement. In this study, polypropylene (PP) fibers were mixed into limestone calcined clay cement-based materials to make new low-carbon ECCs. In this study, a total of 24 sets of specimens were designed for 4 groups of curing ages and 6 types of mix ratios. The compressive load–displacement data were measured the compressive curve characteristics were analyzed then, a compressive constitutive model of the composites was deduced and obtained. Through XRD, SEM-EDS and MIP experiments, the reasons and laws of the compressive strength ranges of adding PP fibers and LC3 to engineered cementitious composites (LC3-PP-ECCs) are further explained from the perspective of the pore size, microstructures and hydration products. The results show that, after 28 days, the compressive strength values of LC3-PP-ECCs generally decreases with increasing PP fiber content and the combined effect of PP fibers and hydration products causes the compressive strength of LC3-ECCs with 0.5% PP fibers to drop sharply. In addition, the specimens showed better properties in terms of toughness, ductility and energy absorption. However, in the microstructures, the addition of PP fibers will cause more internal defects and flaws. This results of this study can provide some theoretical experience and technical support for the engineering application of LC3-ECCs

Mechanics, hydration phase and pore development of embodied energy and carbon composites based on ultrahigh-volume low-carbon cement with limestone calcined clay

Engineered cement-based composites exhibit excellent deformability, mechanical behavior, fresh performance and durability. However, the traditional cement-based composites incorporating high volume ordinary Portland cement would lead to high carbon footprint. In this study, a new and eco-efficient engineered cement-based composites was designed by incorporating Polypropylene fibers (PPF) and eco-friendly cement with limestone calcined clay (LC3-ECCs). The LC3-ECCs were analyzed and discussed in terms of mechanical properties, microscopic morphology, hydration products and porosity. The study found that the 28-days compressive behavior was above 44.2 MPa, and the flexural strength remained above 4.8 MPa. Because of the formation and gathering of highly polymerized compound products (C-S-H gel, C-A-S-H gel) in the matrix and plenty of ettringite, the bonding effect between PPF and LC3 cementitious matrix is better. Additionally, the LC3-ECCs with 1.5 % volume content of PP fiber showed less porosity beneficial to the mechanical behavior. This study suggests that low-carbon LC3 has the potential to be successfully utilized as the alternative to OPC and is suitable to design sustainable ECCs, and this low-carbon construction product can be also generally applied into some area with the abundant clay sources

Formation and evolution of soil salinization based on multivariate statistical methods in Ningxia Plain, China

The Ningxia Plain, situated in the arid zone of northwest China, is a typical dryland plain that faces significant challenges to sustainable agricultural development due to soil salinization. In this study, we employed multivariate analysis and geostatistical methods to investigate the degree and distribution types of soil salinization and the hydrochemical characteristics of shallow groundwater. We also examined the relationship between soil salinization and hydrogeochemical characteristics by analyzing the sources of groundwater ions. This study developed a hydrogeochemical model to describe the soil salinization process in the Ningxia Plain. The results indicate that the majority of surface soils are alkaline type soils, followed by chloride-sulfate type soils. The groundwater is mainly fresh water and brackish water, with a hydrochemical type of SO4·HCO3–Ca·Mg or SO4·Cl–Ca·Mg. Saline water and salt water are represented by Cl–Na·Mg or Cl·SO4–Na·Mg. We also observed spatial trends in groundwater depth and total dissolved solids (TDS) concentrations that were opposite to soil salinity, which suggests a certain degree of second-order trend effect. Furthermore, the degree of soil salinization increased and then decreased from the pre-mountain alluvial plain to the Yellow River alluvial plain, while the groundwater chemistry ranged from simple to complex. The most severe area of soil salinization was found to be concentrated between Hongguang and Yaofu, which is also the area where shallow groundwater salinity accumulation is mainly influenced by continental salinization. In summary, this study provides valuable insights into the hydrogeochemical characteristics of the Ningxia Plain, which can inform strategies for mitigating soil salinization and promoting sustainable agriculture development in arid regions