Curiosity model policy optimization for robotic manipulator tracking control with input saturation in uncertain environment

In uncertain environments with robot input saturation, both model-based reinforcement learning (MBRL) and traditional controllers struggle to perform control tasks optimally. In this study, an algorithmic framework of Curiosity Model Policy Optimization (CMPO) is proposed by combining curiosity and model-based approach, where tracking errors are reduced via training agents on control gains for traditional model-free controllers. To begin with, a metric for judging positive and negative curiosity is proposed. Constrained optimization is employed to update the curiosity ratio, which improves the efficiency of agent training. Next, the novelty distance buffer ratio is defined to reduce bias between the environment and the model. Finally, CMPO is simulated with traditional controllers and baseline MBRL algorithms in the robotic environment designed with non-linear rewards. The experimental results illustrate that the algorithm achieves superior tracking performance and generalization capabilities

Acoustic Vortex in Waveguide with Chiral Gradient Sawtooth Metasurface

The acoustic vortex states with spiral phase dislocation that can carry orbital angular moment (OAM) have aroused many research interests in recent years. The mainstream methods of generating acoustic vortex are based on Huygens-Fresnel principle to modulate the wavefront to create spatial spiral phase dislocation. In this work, we propose an entirely new scenario to generate acoustic vortex in a waveguide with chiral gradient sawtooth metasurface. The physical mechanism of our method is to lift the degenerate dipole eigenmodes through the scattering effect of the chiral surface structure, and then the superposition of them will generate both and order vortices in place. Compared to the existing methods of acoustic vortex production, our design has many merits, such as easy to manufacture and control, the working frequency is broadband, sign of vortex order can be readily flipped. Both the full-wave simulations and experimental measurements validate the existence of the acoustic vortices. The torque effect of the acoustic vortices is also successfully performed by rotating a foam disk as a practical application. Our work opens up a new route for generating acoustic vortex and could have potential significances in microfluidics, acoustic tweezers and ultrasonic communication, etc

Systematic pan-cancer analysis identifies gasdermin B as an immunological and prognostic biomarker for kidney renal clear cell carcinoma

Gasdermin (GSDM)-mediated cell lytic death plays an essential role in immunity and tumorigenesis. Despite the association of gasdermin B (GSDMB) with the tumorigenesis of various cancers, whether GSDMB functions as a prognostic biomarker in renal cell carcinoma remains poorly understood. Here, we explored the potential immunological functions and the prognostic value of GSDMB across multiple tumors with The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases, including analyzing the relationship between GSDMB expression and prognosis, tumor–immune system interactions, immunomodulators, and immune cell infiltration of different tumors. Importantly, elevated expression of GSDMB is an essential factor for the poor prognosis of kidney renal clear cell carcinoma (KIRC) patients, suggesting that it might be helpful to predict a survival benefit from a clinical therapy regimen. Furthermore, GSDMB expression promoted the level of CD4+ T-cell infiltration of the tumors but is significantly negatively associated with immature dendritic cells (iDCs) in KIRC. Additionally, we identified TNFRSF25 and TNFSF14 as immunostimulators highly correlated with GSDMB expression. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) enrichment analyses showed that GSDMB and its interacting proteins might affect tumor growth through the serine metabolism pathway. Our current results demonstrate a promising therapeutic strategy targeting GSDMB and provide new insights into GSDMB as an immunological and prognostic biomarker for KIRC

Occurrence of Scandium in a Ilmenite Ore in Northwest China

This is an essay in the field of process mineralogy. In order to find out the properties of low-grade titanium ore with scandium, chemical analysis, electron microscope, X-ray diffraction, automatic mineral analyzer and optical microscope are used to analyze the material composition and mineral embedding characteristics of the ore. From the perspective of process mineralogy, the occurrence state of titanium, iron, and scandium has been studied in detail. The results show that the scandium in the ore mainly occurs in calcium-magnesium silicate, with a distribution rate of 94.93%. An excellent scandium recovery index can be obtained by beneficiating and smelting this silicate mineral. The research results have important guiding significance for the selection and smelting of scandium associated with titanium ore and the next development and utilization of the deposit. It also has important implications for the study of the occurrence of scandium in similar scandium-bearing titanium deposits

Process Mineralogy of a Titanomagnetite in South Yunnan

This is an essay in the field of process mineralogy. A titanium magnetite ore in Yunnan not only has high iron and titanium, but also is associated with scandium. In order to realize the comprehensive utilization of the ore, the process mineralogy of the ore was studied. The chemical composition of the ore was identified by means of X-ray fluorescence spectroscopy and chemical analysis; The technological characteristics of the minerals were studied by means of X-ray diffraction (XRD), scanning electron microscopy and energy dispersive analysis (SEM-EDS), electron probe microanalysis (EPMA), and the occurrence state of scandium was emphatically investigated. The results show that the main carrier minerals of iron in ore are titanomagnetite and amphibole, followed by ilmenite; The carrier mineral of titanium is mainly ilmenite, with a small amount occurring in sphene; Scandium is mainly distributed in amphibole. The results of elemental distribution show that the theoretical grades of iron, titanium and scandium are 71.02%, 47.40% and 96.63 g/t respectively, and the theoretical recoveries are 40.52%, 66.48% and 97% respectively. The mineralogical factors affecting the recovery index of mineral processing are analyzed, which provides a theoretical support for the subsequent beneficiation and smelting process

Does China's low-carbon city pilot policy promote green development? Evidence from the digital industry

The low-carbon city pilot (LCCP) policy is an essential strategy for China to combat climate change, attain the carbon neutrality target, and achieve comprehensive green transformation, which will inevitably have an impact on many areas of the economic system. The digital economy has given a new impetus to green development and sustainable growth in China, becoming an essential indicator of green transformation. Promoting the digital economy's growth is essential to successful green development. Does China's LCCP policy support digital economy growth while reducing energy use and emissions? This study evaluates digital economy growth in China's 277 cities from 2002 to 2019 using the principal component analysis method and employing the difference-in-differences method to assess how the LCCP policy affects digital economy growth. The empirical results demonstrate that the LCCP policy encourages digital economy growth, which then promotes green development. The conclusion remains tenable following several robustness tests, including parallel trend, placebo, and endogeneity tests. A heterogeneity analysis demonstrates that the LCCP policy has a more profound influence on digital economy growth in coastal, non-resource-based, and large-scale cities. A mechanism test indicates that the LCCP policy positively encourages digital economy growth by promoting technological innovation and changing the industrial structure. This study offers new empirical evidence that LCCP policy can advance the achievement of green development

Distribution and Control of Arsenic during Copper Converting and Refining

Arsenic content in copper concentrates is continuously increasing worldwide. It is desirable to remove arsenic from copper in the earlier stages of copper making due to the deposition of arsenic to cathode copper during the electrorefining process. Effects of temperature, flux, and oxygen on the distribution of arsenic during copper converting and fire refining processes were studied using FactSage 8.2. The results showed that arsenic can be effectively removed by proper selection of converting and refining slags. The decrease in Fe/SiO2 or Fe/CaO ratio in the converting slag is favorable for arsenic distributed to slag. CaO is more effective than SiO2 in decreasing the liquidus temperature of the slag and arsenic content in the blister copper during the converting process. Na2O or CaO as a flux is effective to remove arsenic in the fire refining process

Biodegradable mulch films improve yield of winter potatoes through effects on soil properties and nutrients

Biodegradable mulch films are recognized as a promising substitute of polyethylene (PE) films to alleviate the “white pollution”. Biodegradable mulch films with optimum degradation rates increase crop yield even compared to PE films. However, the mechanisms underlying this yield-increasing effect remains elusive. In this study, three biodegradable film treatments (BFM1, BFM2 and BFM3) and one PE film treatment (PFM) were used to evaluate their effects on soil and winter potatoes, and a partial least squares path model (PLS-PM) was constructed to investigate their relationships. The degradation rates of films under different treatments were ranked as BFM3 > BFM2 >BFM1 > PFM, and presented distinctive effects on soil properties and nutrients, structure of soil bacterial community, and yield traits of winter potatoes. The PLS-PM showed that mulch treatments affected potato yield through effects on soil properties (soil water and temperature) and soil nutrients (TOC, DOC, TN and NO3--N). The disintegration of the biodegradable films decreased soil water content and temperature, and reduced the loss of soil nutrients in the topsoil at the later growth stage of winter potatoes compared to PE films. Additionally, the elevated content of soil TN and NO3--N under treatment BFM1 may play a key role in its yield-increasing effect on potatoes compared to treatments PFM and BFM2. Thus, biodegradable mulch films with proper degradation rates regulate soil TN and NO3--N through their effects on soil water and temperature, and subsequently improve the yield of winter potatoes compared to PE mulch films

Subcortical White Matter Changes with Normal Aging Detected by Multi-Shot High Resolution Diffusion Tensor Imaging.

Subcortical white matter builds neural connections between cortical and subcortical regions and constitutes the basis of neural networks. It plays a very important role in normal brain function. Various studies have shown that white matter deteriorates with aging. However, due to the limited spatial resolution provided by traditional diffusion imaging techniques, microstructural information from subcortical white matter with normal aging has not been comprehensively assessed. This study aims to investigate the deterioration effect with aging in the subcortical white matter and provide a baseline standard for pathological disorder diagnosis. We apply our newly developed multi-shot high resolution diffusion tensor imaging, using self-feeding multiplexed sensitivity-encoding, to measure subcortical white matter changes in regions of interest of healthy persons with a wide age range. Results show significant fractional anisotropy decline and radial diffusivity increasing with age, especially in the anterior part of the brain. We also find that subcortical white matter has more prominent changes than white matter close to the central brain. The observed changes in the subcortical white matter may be indicative of a mild demyelination and a loss of myelinated axons, which may contribute to normal age-related functional decline