RIS-Assisted Physical Layer Authentication for 6G Endogenous Security

The physical layer authentication (PLA) is a promising technology which can enhance the access security of a massive number of devices in the near future. In this paper, we propose a reconfigurable intelligent surface (RIS)-assisted PLA system, in which the legitimate transmitter can customize the channel fingerprints during PLA by controlling the ON-OFF state of the RIS. Without loss of generality, we use the received signal strength (RSS) based spoofing detection approach to analyze the feasibility of the proposed architecture. Specifically, based on the RSS, we derive the statistical properties of PLA and give some interesting insights, which showcase that the RIS-assisted PLA is theoretically feasible. Then, we derive the optimal detection threshold to maximize the performance in the context of the presented performance metrics. Next, the actual feasibility of the proposed system is verified via proof-of-concept experiments on a RIS-assisted PLA prototype platform. The experiment results show that there are 3.5% and 76% performance improvements when the transmission sources are at different locations and at the same location, respectively

Rank Optimization for MIMO systems with RIS: Simulation and Measurement

Reconfigurable intelligent surface (RIS) is a promising technology that can reshape the electromagnetic environment in wireless networks, offering various possibilities for enhancing wireless channels. Motivated by this, we investigate the channel optimization for multiple-input multiple-output (MIMO) systems assisted by RIS. In this paper, an efficient RIS optimization method is proposed to enhance the effective rank of the MIMO channel for achievable rate improvement. Numerical results are presented to verify the effectiveness of RIS in improving MIMO channels. Additionally, we construct a 2$\times$2 RIS-assisted MIMO prototype to perform experimental measurements and validate the performance of our proposed algorithm. The results reveal a significant increase in effective rank and achievable rate for the RIS-assisted MIMO channel compared to the MIMO channel without RIS

Characterization of Pseudomonas spp. and Associated Proteolytic Properties in Raw Milk Stored at Low Temperatures

Milk spoilage is caused by the presence of proteolytic enzymes produced by Pseudomonas spp. during storage at low temperatures. The aim of this study was to identify Pseudomonas spp. in raw milk and investigate their associated proteolytic properties at low temperatures. Raw milk samples (n = 87) were collected from 87 bulk tanks in Shaanxi Province in China. Pseudomonas spp. were identified using Pseudomonas specific 16S, universal 16S rRNA sequencing, and rpoB gene sequencing. The proteolytic properties of Pseudomonas spp. were examined using milk agar, quantitative trinitrobenzenesulfonic acid assay, and by the presence of alkaline metallopeptidase gene (aprX). A total 143 isolates from all 87 samples were confirmed as Pseudomonas, and were identified as belonging to 14 Pseudomonas species. Of these, 40 (28.0%) isolates revealed proteolysis on milk agar at 2°C, 74 (51.8%) at 4°C, 104 (72.7%) at 7°C, and 102 (71.3%) at 10°C. However, proteolytic activity of 45 (31.5%) isolates exceeded 2 μmol of glycine equivalents per mL at 7°C, followed by 43 (30.1%) at 10°C, 18 (12.6%) at 4°C, and 7 (4.9%) at 2°C. The results reveal proteolytic activity of Pseudomonas spp. present in milk and their spoilage potential at different temperatures

Thermodynamic Calculation of Equilibrium Phases of K488 Alloy

The influence of equilibrium and alloy elements on the precipitation phases of K488 alloy was calculated and experimental analyzed by using Thermo-Calc thermodynamic calculation software. The results of calculation and experiment are shown that the alloy equilibrium phases are γ,γ',σ and carbides. In the alloy solidification process, Mo, Ti segregations are more serious. With the increase of C and Nb content, MC precipitation increased, but precipitation temperature decreased, the content of Ti is on the contrary. the increase of Al, Ti contents, γ' phase precipitations amount and precipitation temperature gradually increased. The content of Cr has most influence on the precipitation amount and precipitation temperature of the sigma phase. The calculation and experimental results have good consistency

Phosphogypsum stabilization of bauxite residue: Conversion of its alkaline characteristics

Reduction of the high alkalinity of bauxite residue is a key problem to solve to make it suitable for plant growth and comprehensive utilization. In this study, phosphogypsum, a waste product from the phosphate fertilizer industry, was used to drive the alkaline transformation of the bauxite residue. Under optimal water washing conditions (liquid/solid ratio of 2 mL/g, 30°C, 24 hr), the impact of quantity added, reaction time and reaction mechanism during phosphogypsum application were investigated. Phosphogypsum addition effectively lowered pH levels and reduced the soluble alkalinity by 92.2%. It was found that the concentration of soluble Na and Ca ions in the supernatant increased gradually, whilst the exchangeable Na+ and Ca2 + in solid phase changed 112 mg/kg and 259 mg/kg, respectively. Ca2 + became the dominant element in the solid phase (phosphogypsum addition of 2%, liquid/solid ratio of 2 mL/g, 30°C, 12 hr). X-ray diffraction data indicated that cancrinite and hydrogarnet were the primary alkaline minerals. SEM images suggested that phosphogypsum could promote the formation of stable macro-aggregates, whilst the content of Ca2 + increased from 5.6% to 18.2% and Na reduced from 6.8% to 2.4%. Treatment with phosphogypsum could significantly promote the transformation of alkalinity cations by neutralization, precipitation and replacement reactions. This research provided a feasible method to promote soil formation of bauxite residue by phosphogypsum amendment.</p

Characterization of Pseudomonas spp. and Associated Proteolytic Properties in Raw Milk Stored at Low Temperatures

TesisSe realizó un estudio comparativo, transversal y prospectivo en dos grupos de mujeres durante el climaterio procedentes de la zona urbana y rural del distrito de Ayacucho, para determinar la influencia de los factores sociales y culturales en la calidad de vida de la mujer durante el climaterio. La información se recolectó por medio de un cuestionario que contenía una encuesta de carácter social y cultural, se entrevistaron al efecto 100 mujeres entre 35 a 64 años edad en cada zona y con residencia permanente. Se utilizó las técnicas de encuesta, la escala de Lickert, como también se consideró el perfil de salud de Nottingham para evaluar el nivel de conocimiento del climaterio y el cuestionario de MENQOL para valorar la calidad de vida del climaterio. Se encontró que la edad promedio de la premenopausia es de 41.1(DS=4.4) en las mujeres de la zona urbana y 39.4(DS=3.3) en las de la rural y de la posmenopausia 54.3(DS=6.2) en la urbana y de 55.3(DS=6.9) en rural. La edad promedio de la menopausia es de 48 años (DS 5,05) y de 45 (DS 4,76) en la zona urbana y rural respectivamente. El síntoma más frecuente en el síndrome clínico fue la cefalea como síntoma general y las oleadas de calor en el síntoma vasomotor, tanto en la premenopausia como en la posmenopausia, con 81,0% y 64% en la urbana y con 94,0% y 47% en el rural; de igual forma, con respecto al síndrome psicológico se observa, la irritabilidad y la depresión con 81,0% y 75% en la urbana y 85,0% y 65% para la rural. Contrastando la hipótesis a través del test estadístico Chi cuadrado con un nivel de confianza mayor del 95%, se concluye que, "los factores sociales como: tipo de comunicación y relación interfamiliar y los factores culturales como: grado de instrucción y nivel de conocimiento sobre el climaterio influyen en la calidad de vida de la mujer durante el climaterio, rechazándose la hipótesis nula a favor de la alterna. Se considera de suma importancia profundizar el estudio de la influencia de los factores sociales y culturales, así mismo, se sugiere la necesidad urgente de realizar proyectos en el ámbito regional y local de prevención primaria mediante programas de comunicacion e información del conocimiento integral sobre el climaterio a partir de la niñez, así como, identificando a las mujeres con síndrome climatérico para su respectivo tratamiento especializado. Por lo que será necesario y de suma importancia una mejor implementación de los centros educativos y los servicios de salud, para lo cual es preciso crear un sistema de apoyo integral médico, psicológico, social y educativo específico

Bio-Organic Fertilizer Combined with Different Amendments Improves Nutrient Enhancement and Salt Leaching in Saline Soil: A Soil Column Experiment

Salt-affected soils frequently experience leaching and desalination issues, which severely restrict plant growth and water uptake. Hence, in this experiment, four treatments including CG (no amendments addition); OF (organic fertilizer addition); OH (organic fertilizer and Hekang amendment addition); and OB (organic fertilizer and fulvic acid addition) were designed to examine the effect of organic amendment on soil chemical properties, water and salt transport, and soil desalination laws of coastal saline soil. The results showed that the addition of organic amendments significantly reduced soil pH (8.47&ndash;8.52) and salt content (2.06&ndash;2.34 g kg&minus;1), while increasing soil organic matter content, available phosphorus, and available potassium. OH treatment has a higher available phosphorus content than other treatments. OH and OB treatments elevated the soil desalination ratio (32.95% and 32.12%, respectively) by raising the leaching volume and leaching rate. Organic amendments significantly promoted Na+ (4.5&ndash;32%) and SO42&minus; (12&ndash;27%) leaching compared to CG. Organic treatments, particularly OB treatment, not only increased the content of soil organic matter and available nutrients but also promoted salt ion leaching, improved soil permeability and increased soil desalination and water leaching rates. Our results may provide a theoretical basis for revealing the desalination law of coastal saline soil

Time-domain channel measurements and small-scale fading characterization for RIS-assisted wireless communication systems

Reconfigurable intelligent surfaces (RISs) have attracted extensive attention from industry and academia. In RIS-assisted wireless communication systems, practical channel measurements and modeling serve as the foundation for system design, network optimization, and performance evaluation. In this paper, a RIS time-domain channel measurement system, based on a software defined radio platform, is developed for the first time to investigate the small-scale fading characteristics of RIS-assisted channels. We present RIS channel measurements in corridor and laboratory scenarios and compare the power delay profile of the channel without RIS, with RIS specular reflection, and with RIS intelligent reflection. The multipath component parameters and cluster parameters based on the Saleh–Valenzuela model are extracted. We find that the power delay profiles(PDPs)of the RIS-assisted channel fit the power-law decay model better than the common exponential decay model and approximate the law of square decay. Through intelligent reflection, the RIS can decrease the delay and concentrate the energy of the virtual line-of-sight (VLoS) path, thereby reducing the delay spread and mitigating multipath fading. Furthermore, the cluster characteristics of RIS-assisted channels are highly dependent on the measurement environment. In the laboratory scenario, a single cluster dominated by the VLoS path with smooth envelope is observed. On the other hand, in the corridor scenario, some additional clusters introduced by the RIS reflection are created.<br/