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Industrial robots are widely used in various industrial fields, such as handling and welding, due to their good repeat positioning accuracy. The motion error determines the absolute accuracy. For robot design, dimensional parameter errors and drive parameter errors, a mathematical model of a kinematic exponential product with error screws was proposed. The influence of different rod lengths and transmission errors on the accuracy of the end motion was analysed. A composite analysis method based on screw theory and vector method is proposed for the spatial deflection error of robot rotating joints with clearance. By using screw theory, a mathematical error model of the axial movement and spatial deflection of the joint gap was established. A mathematical model of joint space radial movement was established by using the three-dimensional vector method. Through numerical simulation, the position distribution law of the random error of the robot terminal in the workspace and the distribution of the plane projection density were obtained. By solving the attitude matrix, the distribution of each Euler angle error was obtained. A simulation test was carried out to verify the model's correctness. The calculation showed that the method is simple and correct, and the obtained error distribution characteristics are of great significance to improving robotic kinematic calibration accuracy and optimising the spatial position error distribution. [ABSTRACT FROM AUTHOR]

In this study, a new type of multi-arch tunnel construction method is proposed. This effort is undertaken due to the many disadvantages of the traditional multi-arch tunnel construction method. Furthermore, this method omits the construction of a middle pilot tunnel, and it has the advantages of safety, high efficiency, and being economical. When using the method of continuous arch tunneling without a middle pilot tunnel, the blasting of the first tunnel and the following tunnel has a greater impact on the surrounding rock damage, as well as on the supporting structure of the same cross-section. Therefore, this study uses LS-DYNA finite element software to construct a three-dimensional numerical model. In addition, the perimeter rock damage law and mechanical response characteristics of the supporting structure in the same cross-section of the first tunnel, as well as the following tunnel after blasting without a middle pilot tunnel, are analyzed. At the same time, the results of the study are based on optimizing the blasting program, and these are then applied to the field. Through the results, it is found that, after blasting a continuous arch tunnel without a medial pilot tunnel, the surrounding rock damage in the arch cross-region of the double-arch tunnel (where the arch top and the arch shoulder are more significant) and the effective stress of the supporting structure exceed the strength design value. In addition, the maximum adequate pressure is distributed in the medial diaphragm wall. With the optimized blasting scheme, the range of the peripheral rock damage is reduced by a maximum of 67%, and the effective stress in the supporting structure is reduced by 25.9–64.8%. The research results are of great significance in terms of improving construction safety, economic efficiency, and project quality, as well as in promoting the research and development of new work methods for double-arch tunnels. [ABSTRACT FROM AUTHOR]

This paper presents a copula technique to develop time-variant seismic fragility curves for corroded bridges at the system level and considers the realistic time-varying dependence among component seismic demands. Based on material deterioration mechanisms and incremental dynamic analysis, the time-evolving seismic demands of components were obtained in the form of marginal probability distributions. The time-varying dependences among bridge components were then captured with the best fitting copula function, which was selected from the commonly used copula classes by the empirical distribution based analysis method. The system time-variant fragility curves at different damage states were developed and the effects of time-varying dependences among components on the bridge system fragility were investigated. The results indicate the time-varying dependence among components significantly affects the time-variant fragility of the bridge system. The copula technique captures the nonlinear dependence among component seismic demands accurately and easily by separating the marginal distributions and the dependence among them. [ABSTRACT FROM AUTHOR]

In this article, the issue of neural adaptive decentralized finite-time prescribed performance (FTPP) control is investigated for interconnected nonlinear time-delay systems. First, to bypass the potential singularity difficulties, the hyperbolic tangent function and the radial basis function neural networks are integrated to handle the unknown nonlinear items. Then, an adaptive FTPP control strategy is developed, where an improved fractional-order filter is applied to tackle the tremendous "amount of calculation" and eliminate the filter error simultaneously. Furthermore, by considering the impact of bandwidth limitation, an adaptive self-triggered control law is designed, in which the next trigger instant is determined through the current information. Ultimately, it can be demonstrated that the proposed control scheme not only guarantees that all states of the closed-loop system are semi-globally uniformly ultimately bounded, but also that the system output is confined to a small area in finite time. Two simulation examples are carried out to verify the effectiveness and superiority of the proposed method. [ABSTRACT FROM AUTHOR]

The rapid and precise monitoring of peripheral blood miRNA levels holds paramount importance for disease diagnosis and treatment monitoring. In this study, we propose an innovative research strategy that combines the catalytic hairpin assembly reaction with SERS signal congregation and enhancement. This combination can significantly enhance the stability of SERS detection, enabling stable and efficient detection of miRNA. Specifically, our paper-based SERS detection platform incorporates a streptavidin-modified substrate, biotin-labeled catalytic hairpin assembly reaction probes, 4-ATP, and primer-co-modified gold nanoparticles. In the presence of miRNA, the 4-ATP and primer-co-modified gold nanoparticles can specifically recognize the miRNA and interact with the biotin-labeled CHA probes to initiate an interfacial catalytic hairpin assembly reaction. This enzyme-free high-efficiency catalytic process can accumulate a large amount of biotin on the gold nanoparticles, which then bind to the streptavidin on the substrate with the assistance of the driving liquid, forming red gold nanoparticle stripes. These provide a multitude of hotspots for SERS, enabling enhanced signal detection. This innovative design achieves a low detection limit of 3.47 fM while maintaining excellent stability and repeatability. This conceptually innovative detection platform offers new technological possibilities and solutions for clinical miRNA detection. [ABSTRACT FROM AUTHOR]

This paper focuses on the state estimation issue of T–S fuzzy Markovian generalized neural networks (GNNs) with reaction–diffusion terms. An estimator-based nonfragile time-varying proportional retarded sampled-data controller that permits norm-bounded indeterminacy and contains a time-varying delay is designed to guarantee the asymptotical stability of the error system. By establishing a novel Lyapunov–Krasovskii functional that involves positive indefinite items and discontinuous items, meanwhile, by combining the reciprocally convex combination method, Jenson's inequality and Wirtinger inequality, a less conservative stability criterion can be derived. Moreover, the principle for the number of selected variables in the process of deriving main results is also analyzed. Finally, two numerical examples are given to demonstrate the validity and advantages of the results proposed in this paper. [ABSTRACT FROM AUTHOR]

This paper addresses the intermittent pinning synchronization problem of spatial diffusion coupled reaction–diffusion neural networks (RDNNs). Initially, the synchronization error signals are quantized before transmission to save both channel resource and control cost. Subsequently, utilizing intermittent pinning control scheme, only a small fraction of network nodes are selected to be controlled in various time periods, which further reduces the control cost. On the basis of the constructed controller, sufficient conditions that guarantee the synchronization of the coupled RDNNs are derived via Lyapunov direct method. Finally, the efficacy of the developed control approach is demonstrated by numerical simulation studies of three examples. [ABSTRACT FROM AUTHOR]

Studies of the mechanical response behavior of slate and the establishment of corresponding damage-ontological relationships are crucial for improving safety and avoiding disasters in construction projects. For the study reported in this paper, we first assumed that slate is a transverse isotropic body. Next, to characterize disparities in elastic characteristics between axial and radial orientations, we introduced five distinct elastic parameters for these two directions. Specifically, these parameters were Young’s modulus E1, Poisson’s coefficient v1 (associated with parallel bedding planes), Young’s modulus E2, Poisson’s coefficient v2, and shear modulus G2 (associated with perpendicular bedding planes). We then established a statistical damage-evolution equation for transverse isotropic slate based on a lognormal distribution, and we constructed a statistical damage-constitutive model for laminated slate under three-way stress by considering the shear–slip deformation and closure deformation of the laminated surface. Finally, we demonstrated the effectiveness of our model by comparing its output data with results obtained in triaxial compression tests on slate. We found that the differential stress–strain curves obtained from the model and the tests were in good agreement in the peak front. Average relative errors of 15.62% and 16.19% were recorded for cases of 5 Mpa and 10 Mpa of enclosing pressure, respectively. The rationality of the established transverse isotropic slate damage-constitutive relationship was therefore proved. [ABSTRACT FROM AUTHOR]

As long-standing clinical problems, a series of complicated infections are more difficult to treat due to the development of antibiotic resistance, especially caused by methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), and multidrug-resistant Mycobacterium tuberculosis (M. tuberculosis). Moreover, the treatment options available to against these infections are also becoming increasingly limited. Linezolid is the first synthetic oxazolidinone antibiotic with a unique mechanism of action, and its efficacy against Gram-positive bacteria has been clearly demonstrated. However, the limitations of linezolid alone for the treatment of these complicated infections have been reported in the recent years. Combination therapy may be a good approach to enhance efficacy and prevent the development of resistance. In this review, the results of multiple linezolid combination therapies from in vitro, animal studies, and clinical cases for the treatment of MRSA, VRE, and multidrug-resistant M. tuberculosis strains will be discussed, and thus provide more relevant information for clinician in clinical practice. [ABSTRACT FROM AUTHOR]

A detailed understanding of damage evolution in rock after high-temperature treatment in unloading conditions is extremely important in underground engineering applications, such as the disposal of highly radioactive nuclear waste, underground coal gasification, and post-disaster reconstruction. We have studied the effects of temperature (200, 400, 600 and 800 °C) and confining pressure (20, 30 and 40 MPa) on the mechanical properties of sandstone. Scanning electron microscopy studies revealed that at temperatures exceeding 400 °C, new cracks formed, and original cracks extended substantially. When the confining pressure was 20 MPa, a temperature increase from 400 to 800 °C resulted in a 75.2% increase in peak strain, a decrease in Young's modulus and peak strength of 62.5 and 35.8 %, respectively, and transition of the failure mechanism from brittleness to ductility. In the triaxial compression tests, the specimen deformed in a more obvious ductile failure manner at higher confining pressure, whereas in the unloading confining pressure experiments, brittle failure was more obvious when the initial confining pressure was higher. We focused on the effects of temperature and initial confining pressure on peak effective loading stress and peak ductile deformation during unloading. At temperatures of >400 °C, the peak ductile deformation increased rapidly with increases in the high temperature treatment or initial confining pressure. The peak effective loading stress decreased sharply with increased temperature but barely changed when the initial confining pressure was varied. [ABSTRACT FROM AUTHOR]

The simulations of a heat wave occurring in southern Yangtze-Huaihe valley and southern China during late July, 2003 were conducted to examine the sensitivity of simulated surface air temperature (SAT) to different land surface schemes (LSSs) using the Weather Research and Forecasting Model (WRF) Version 2.2 in the short-range mode for 24-h integrations. Initial and boundary conditions employed a National Centers for Environmental Prediction (NCEP) analysis. The results showed that, overall, simulated high-temperature weather is sensitive to different LSSs. Large differences in simulated SAT intensity, threat score, and simulated error under different schemes are identified clearly. In addition, some systematic differences are also induced by the LSSs. In terms of threat score from the three LSSs, SLAB is the best, and RUC is better than NOAH. SLAB gives the lowest absolute error for area-averaged SAT, and tends to depict the western Pacific subtropical high with the easternmost position at low levels. The LSSs modify the simulated SAT, primarily via the transfer of sensible heat from the land surface to the atmosphere. The physical mechanism of the positive feedback between atmospheric circulation and the SAT is unimportant, with 'negative' feedback over most of the simulated areas. This study emphasizes the importance of improving LSSs in SAT forecasting by numerical models. [ABSTRACT FROM AUTHOR]