Disturbance Rejection Control for Autonomous Trolley Collection Robots with Prescribed Performance

Trajectory tracking control of autonomous trolley collection robots (ATCR) is an ambitious work due to the complex environment, serious noise and external disturbances. This work investigates a control scheme for ATCR subjecting to severe environmental interference. A kinematics model based adaptive sliding mode disturbance observer with fast convergence is first proposed to estimate the lumped disturbances. On this basis, a robust controller with prescribed performance is proposed using a backstepping technique, which improves the transient performance and guarantees fast convergence. Simulation outcomes have been provided to illustrate the effectiveness of the proposed control scheme

Quantitative characterization of the disturbance of groundwater system in typical coal seam mining in contiguous area of Inner Mongolia and Shaanxi

High-intensity mining of coal mines in ecologically fragile areas disturbs the groundwater system and causes water resources loss. The typical shallow and deep mining mines in the middle section of the Yellow River basin are selected as the research objects, and the development height of the water-conducting fracture zone in the shallow composite coal seam mining and the deep single coal seam mining is comprehensively determined by using the theoretical analysis, numerical simulation of overburden damage and the underground measurement, and the comparison with surrounding mines with similar conditions. According to the spatial location relationship between the water-conducting fracture zone and the main roof aquifer/aquiclude, the water filling model of Zhiluo Formation - Zhidan Group aquifer in shallow coal seam mining and that of Zhiluo Formation aquifer in deep coal seam mining are divided; By generalizing the groundwater flow system of different aquifer water filling modes, the three-dimensional unsteady flow mathematical model of groundwater in typical coal seam mining is constructed, and the numerical model of groundwater flow in two working conditions is established by using Visual Modflow software. The quantitative prediction of groundwater flow field and water resource loss in the mining of the continuous working face is carried out, and the results show that the groundwater from Zhidan Group and Zhiluo Formation aquifers in the disturbed aquifer is converging towards the goaf at the same time, the flow field also gradually recovers with the formation of the secondary stable structure of the roof after mining. Around the goaf, the groundwater flow field shows a local high hydraulic gradient phenomenon; In addition, the average annual water loss of the two coal mining conditions in the continuous period is more than 2 million m3 and 7.3 million m3 respectively. The research results provide a reference for the advanced fine control of regional water resources loss and the utilization of mine water resources

Pistis:Replay Attack and Liveness Detection for Gait-Based User Authentication System on Wearable Devices Using Vibration

Wearable devices-based biometrics has become mainstream in the biometric domain, especially in mobile computing, due to its convenience, flexibility, and potentially high user acceptance. Among various modalities, wearable devices-based gait recognition has been recognized as an effective user authentication method and employed in various applications, such as automated entry systems for home, school, work, vehicles, and automated ticket payment/validation for public transport. However, how secure wearable gait remains an open research question. In this study, we conduct a comprehensive security analysis of the wearable gait. Then, we demonstrate that gait itself is not robust against some attacking methods, such as spoofing or forgery. Therefore, we argue that an anti-spoofing mechanism is important for enhancing the security of wearable gait biometric systems. To this end, we proposed a novel authentication protocol called Pistis that embedded gait biometrics and a liveness detection mechanism that is aiming to detect various attacks of gait authentication systems. Our extensive experiments based on 50 subjects demonstrate that Pistis is effective in liveness detection and authentication performance enhancement, providing 100% accuracy for human and nonhuman detection, and 99.53% accuracy for user authentication. Pistis can be used as a liveness detection method for wearable devices-based biometrics, significantly for wearable gait.</p

The Investigation of LRP5-Loaded Composite with Sustained Release Behavior and Its Application in Bone Repair

Low-density lipoprotein receptor-related protein 5 (LRP5) plays a vital role in bone formation and regeneration. In this study, we developed an injectable and sustained-release composite loading LRP5 which could gelatinize in situ. The sustained release of the composite and its efficacy in bone regeneration were evaluated. Sodium alginate, collagen, hydroxyapatite, and LRP5 formed the composite LRP5-Alg/Col/HA. It was found that the initial setting time and final setting time of LRP5-Alg/Col/HA containing 4% alginate were suitable for surgical operation. When the composite was loaded with 40 μg/mL LRP5, LRP5-Alg/Col/HA did not exhibit a burst-release behavior and could sustainably release LRP5 up to 21 days. Up to 18 days, LRP5 released from LRP5-Alg/Col/HA still present the binding activity with DKK1 (Wnt signaling pathway antagonist) and could increase the downstream β-catenin mRNA in bone marrow mesenchymal stem cells. Moreover, LRP5-Alg/Col/HA was found to significantly increase bone mineral density in the defect area after 6 weeks’ implantation of LRP5-Alg/Col/HA into the rats’ calvarial defect area. H&E staining detection demonstrated that LRP5-Alg/Col/HA could mediate the formation of a new bone tissue. Therefore, we concluded that Alg/Col/HA was a suitable sustained-release carrier for LRP5 and LRP5-Alg/Col/HA had a significant effect on repairing bone defects and could be a good bone regeneration material

A New Wood Adhesive Based on Recycling <i>Camellia oleifera</i> Cake-Protein: Preparation and Properties

In order to improve the initial viscosity and stability of Camellia oleifera cake-protein adhesive, Camellia oleifera cake-protein was blended with defatted soybean protein (DSP), soybean protein isolate (SPI), and casein, followed by adhesive preparation through degradation and crosslinking methods. The performance of Camellia oleifera cake-protein adhesive was investigated by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), scanning electron microscopic (SEM), and thermogravimetric (TG) and X-ray diffraction (XRD). The results showed that DSP, SPI, and casein likely promoted the effective degradation of Camellia oleifera cake-protein, and, thus, more active groups were formed in the system, accompanied by more reactivity sites. The prepared adhesive had a lower curing temperature, and higher initial viscosity and stability, but the storage time was shortened. Moreover, DSP, SPI, and casein, themselves, were degraded into peptide chains with lower molecular weights; thus, improving the overall flexibility of the adhesive, facilitating a better elastic contact and regular array between crosslinking products, and further strengthening the crosslinked structure and density of the products. After curing, a compact and coherent reticular structure was formed in the adhesive layer, with both bonding strength and water resistance being significantly improved. According to the results obtained, the next step will be to study the DSP-modified Camellia oleifera cake-protein adhesive in depth

One Single Amino Acid for Estimation the Content of Total Free Amino Acids in Qingkailing Injection Using High-Performance Liquid Chromatography-Diode Array Detection

Qingkailing injection (QKLI), a modern traditional Chinese medicine preparation, has been widely used in clinics due to its fast and significant efficacy in treatment of high fever. The free amino acids (AAs) were considered to be the most abundant active ingredients indisputably. So developing an accurate and simple determination method to measure the contents of total free AAs in QKLI is very crucial. In current study, the accurate and simple method of using one single standard AA for simultaneous quantification of multiple AAs (One for M) in QKLI was developed. Particularly, the calculation methods and the robustness of relative correction factors (RCFs) were investigated systematically. No statistically significant difference between these two quantification methods of One for M and classic regression equation was found by the t-test (P  =  95%, P>0.05). The results showed that the precision (RSD < 4.88%), the robustness (RSD < 4.04%), and the average recoveries (94.11%–107.94%) of this newly proposed method all met the requirements for content determination. This One for M method will provide a scientific reference for the quantitative determination of AAs in other traditional Chinese medicines and their preparations owing to its accuracy and simplicity

Synergetic Effect of Co-pyrolysis of Cellulose and Polypropylene over an All-Silica Mesoporous Catalyst MCM-41 Using Thermogravimetry–Fourier Transform Infrared Spectroscopy and Pyrolysis–Gas Chromatography–Mass Spectrometry

Biomass is one of the promising alternative materials to solve the energy and environmental crisis. Fast pyrolysis is one of the most economical and commercially realizable technologies to convert biomass to useable fuels and chemicals. To improve the liquid products, co-pyrolysis with polypropylene (PP) over a mesoporous catalyst MCM-41 was studied in this paper. Thermogravimetry–Fourier transform infrared spectroscopy (TG–FTIR) and pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) were used as the main analysis methods to study the mass loss and detailed products of the co-pyrolysis. The mass loss, main functional groups, and identified products of pyrolysis of cellulose, PP, and their mixture were analyzed and discussed. All of the TG, FTIR, and Py–GC–MS data show that there is no significant synergism between cellulose and PP when simply mixing them, although the C/H_eff of the mixture increases from 0 to 1.3. However, the addition of MCM-41 bring significant synergism. The TG and differential thermogravimetry (DTG) data show that the co-pyrolysis with MCM-41 shifts the decomposition of PP to a lower temperature, which provides more overlap between cellulose and PP in the range of 300–400 °C. According to the FTIR spectra, CO, CO₂, and carbonyl are also produced in the peak for pyrolysis of PP for the mixture together with MCM-41, which indicates the intermolecular synergetic reaction. Furthermore, the results from Py–GC–MS show that olefins (43.9%), oxygenated compounds (24.8%, mainly alcohols), and aromatics (17.8%) are the main products of co-pyrolysis of cellulose and PP in the presence of MCM-41, while oxygenated compounds (82.2%, mainly saccharides), olefins (4.7%), and aromatics (1.1%) will be the main products without the catalyst. Olefins and alcohols are much more than the calculated value, which is the main result of synergism. Alcohols are mainly produced from the radical from the cracking of PP combined with the hydroxyl radical produced from decomposition of cellulose. Olefins are produced from the interaction reaction (carbenium ion reaction and β-scission) between the primary products of cellulose and the hydrocarbon pool reaction of primary products of cellulose and PP. The results of this study enhance the understanding of co-pyrolysis of cellulose and PP in the presence of MCM-41 and provide the possible pathway of modifying the special pyrolysis products in catalytic pyrolysis of biomass with polymers

Optimization, characterization and evaluation of ZnO/polyvinylidene fluoride nanocomposites for orthopedic applications: improved antibacterial ability and promoted osteoblast growth

Herein, electrospun zinc oxide nanoparticle/poly (vinylidene fluoride) (ZnONP/PVDF) composite fiber membranes were designed, fabricated, and tested for improved orthopedic applications. A single factor screening study was conducted to determine the optimal ZnONP/PVDF formulation based on osteoblast (bone forming cells) proliferation and antibacterial properties. Further, ZnONP/PVDF materials were characterized for their morphology, crystallinity, roughness, piezoelectric properties, and chemistry to understand such cell results. The optimal concentration of high molecular weight PVDF (18%, w/v) and a low concentration of ZnONPs (1 mg/ml) were identified for electrospinning at room temperature in order to inhibit bacterial colonization (without resorting to antibiotic use) and promote osteoblast proliferation. Compared to no ZnO/PVDF scaffold without Piezo-excited group,the study showed that on the 1 mg/ml ZnO/PVDF scaffolds with piezo-excitation, the density of SA and E.coli decreased by 68% and 56%.The density of osteoblasts doubled within three days(compared to the control). In summary, ZnONP/PVDF composite fiber membranes were formulated by electrospinning showing an exceptional ability to eliminate bacteria colonization while at the same time promote osteoblast functions and, thus, they should be further studied for a wide range of orthopedic applications