•A performance-balanced system is built to enrich the research on balanced systems.•A two-step FMCIA is constructed to derive system reliability.•An integrated maintenance policy is designed for the ...proposed model.
Due to practical engineering applications, the research on balanced systems has moved into development in recent years. The concept of balance differs from various perspectives and more reliability problems on balanced systems need to be further investigated. The system consists of multiple components with two-stage lifetime. When the locations of the components which are in poor operation stage concentrate in a particular range in the system, the high level of non-uniformed operation states of the components would speed up the failure process of the whole system. The interpretation of this real engineering situation is defined as that the system loses the performance balance and then the performance-balanced system with three competing criteria of system performance imbalance is established in this paper. A two-step finite Markov chain imbedding approach is employed to derive probabilistic indices both for components and whole system which operate in a shock environment. A combined maintenance policy is designed for the proposed model and an optimization model is constructed by minimizing mean maintenance cost. Numerical examples based on a battery pack system have served the purpose to present to applicability of the performance-balanced systems and the effectiveness of the proposed approach.
Monolayers of transition-metal dichalcogenides (TMDs) exhibit numerous crystal phases with distinct structures, symmetries and physical properties1-3. Exploring the physics of transitions between ...these different structural phases in two dimensions4 may provide a means of switching material properties, with implications for potential applications. Structural phase transitions in TMDs have so far been induced by thermal or chemical means5,6; purely electrostatic control over crystal phases through electrostatic doping was recently proposed as a theoretical possibility, but has not yet been realized7,8. Here we report the experimental demonstration of an electrostatic-doping-driven phase transition between the hexagonal and monoclinic phases of monolayer molybdenum ditelluride (MoTe2). We find that the phase transition shows a hysteretic loop in Raman spectra, and can be reversed by increasing or decreasing the gate voltage. We also combine second-harmonic generation spectroscopy with polarization-resolved Raman spectroscopy to show that the induced monoclinic phase preserves the crystal orientation of the original hexagonal phase. Moreover, this structural phase transition occurs simultaneously across the whole sample. This electrostatic-doping control of structural phase transition opens up new possibilities for developing phase-change devices based on atomically thin membranes.
•A multi-state shock model with three types of shocks is proposed.•The failure pattern mutates when the system state drops to a lower one.•The finite Markov chain imbedding approach is used to obtain ...reliability indices.•The phase-type distribution is used to depict the interarrival time of two shocks.•Three different replacement policies are proposed for the new model.
In this paper, to accommodate the known fact that a multi-state system is more likely to fail when its state gets worse, a multi-state shock model is proposed, in which the system failure patterns are mutative for different states. Shocks are classified into type I, type II and type III by magnitude. A type III shock has a destructive effect on the system and causes a complete failure whenever it occurs. A type II shock triggers the system down to a lower state. The system completely fails when the additive number of type II shocks exceeds a threshold. A type I shock has different effects for different system states. The system completely fails if the cumulative number of type I shocks exceeds a threshold which decreases as the system state gets lower. Distributions of the lasting time until the end of each system state, the lifetime and the residual lifetime of the system are derived when the interarrival times between successive shocks follow a common continuous phase-type distribution. Three different replacement policies are proposed to fit the characteristic of the new model, and corresponding optimization models are constructed to gain the optimal quantities.
The article examines the essential and logical-hierarchical relationships of such concepts as poetic discourse, poetic language, and the language of poetry. The relevance of the research is ...determined by fact that the understanding and interpretation of poetic discourse within the framework of the scientific theory is in a state of development, the methodology of literary criticism and linguistics is evolving, and many concepts are still confused. Opinions expressed by the researchers who have studied the essence of poetic language and language of poetry, as well as support the concept of poetic discourse, are analyzed. The main results of the study include the definition of concepts of ethical discourse, poetic language, and the language of poetry in close logical and epistemological relationship with each other. Based on the obtained results, the following conclusions are made. Firstly, the phenomenal essence of poetic language is described. Secondly, the mechanism of poetic discourse development is viewed as a result of two refractions (author’s and reader’s) of the language of poetry. At the same time, the language of poetry is presented as a locus (modus) of a worldview or a linguistic worldview. Thirdly, poetic discourse is considered as part of artistic discourse, which is not only emotional and aesthetic, but also cognitive and aesthetic content. The above-given conclusions are important for the theory of linguistics and literary criticism, because they contain the rationale for the statement that poetic discourse is a level of understanding and interpretation of the language of poetry as a mode of the linguistic reality. At the same time, poetic language is a skillfully applied technological side of a special kind of creative, heuristic activity.
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In recent years, transdermal preparations have emerged as one of the most promising modes of administration. In particular, dissolving microneedles have attracted extensive attention ...because of their painlessness, safety, high delivery efficiency and easily operation for patients. This article mainly reviews the preparation methods, the types of matrix polymer materials, the content of dissolving microneedles performance testing, and the applications of dissolving microneedles. It is expected to lay a solid knowledge foundation for the in-depth study of the dissolving microneedles.
Water and electricity scarcity are two global challenges, especially in arid and remote areas. Harnessing ubiquitous moisture and sunlight for water and power generation is a sustainable route to ...address these challenges. Herein, we report a moisture-induced energy harvesting strategy to realize efficient sorption-based atmospheric water harvesting (SAWH) and 24-hour thermoelectric power generation (TEPG) by synergistically utilizing moisture-induced sorption/desorption heats of SAWH, solar energy in the daytime and radiative cooling in the nighttime. Notably, the synergistic effects significantly improve all-day thermoelectric power density (~346%) and accelerate atmospheric water harvesting compared with conventional designs. We further demonstrate moisture-induced energy harvesting for a hybrid SAWH-TEPG device, exhibiting high water production of 750 g m
, together with impressive thermoelectric power density up to 685 mW m
in the daytime and 21 mW m
in the nighttime. Our work provides a promising approach to realizing sustainable water production and power generation at anytime and anywhere.
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•Cellulose-rich grass clipping showed great potentials for biofuel production.•Ultrasound-Ca(OH)2 was the most effective pretreatment method.•Pretreatment removed lignin and ...hemicellulose, and increased crystallinity index.•Reducing sugar yield of grass clipping reached 414mg/g after pretreatment.
Grass clipping, a cellulose-rich raw material, has great potential to produce biofuels, but must be firstly hydrolyzed to liberate fermentable sugars. In this study, grass clipping was pretreated with ultrasound (US), Ca(OH)2, NaOH, US-Ca(OH)2 and US-NaOH at relatively low temperature to enhance its enzymatic hydrolysis. The solubilization of hemicellulose and lignin, and crystallinity index of cellulose increased after US-alkaline pretreatment, leading to a significant increase of enzyme accessibility to cellulose. Compared with another four pretreatments, US-Ca(OH)2 pretreatment of grass clipping showed the best improvement for reducing sugar yield. X-ray diffraction (XRD) determination and scanning electron microscope (SEM) observation showed that the crystallinity index of grass clipping increased and the grass clipping surface suffered from serious erosion after US-Ca(OH)2 pretreatment. Then, the operating conditions of US-Ca(OH)2 pretreatment and enzymatic hydrolysis were systematically optimized, and the suitable operating conditions were as follows: US power density of 0.65W/ml, US pretreatment time of 30min, Ca(OH)2 concentration of 0.75%, pretreatment temperature of 75°C, enzyme loading of 125FPU/g, and hydrolysis time of 72h. The reducing sugar yield of grass clipping pretreated by US-Ca(OH)2 reached 414mg/g, increasing by 3.5 times compared with that of raw grass clipping. The US-Ca(OH)2 pretreatment of grass clipping at low temperature significantly enhanced the potential of grass clipping as a promising raw material to produce biofuels.
Chronic kidney disease (CKD) affects 10-15% of the population worldwide, results in high morbidity and mortality, and requires costly treatment and renal replacement therapy. Glomerulosclerosis, ...tubulointerstitial fibrosis, and persistent intestinal flora disturbance are common in CKD. Short-chain fatty acids (SCFAs), produced by the intestinal microbiota, have been previously reported to ameliorate kidney injury; however, the specific concentrations and types that are required to improve renal function remain unknown. The present study aims to evaluate the levels of SCFAs in healthy and CKD patients, and to test the hypothesis that SCFAs play a critical role in delaying CKD progression. One hundred and twenty-seven patients with CKD and 63 healthy controls from China were enrolled in the present study. Butyrate, which is considered beneficial to humans, was almost three-times higher in healthy volunteers than that in CKD5 subjects (
=0.001). Moreover, the serum SCFA levels in controls were significantly higher than that in CKD patients (
<0.05), and the butyrate level among CKD5 patients (1.48 ± 0.60 μmol/l) was less than half of that in controls (3.44 ± 2.12 μmol/l,
<0.001). In addition, we observed an inverse correlation between butyrate level and renal function (
<0.05). A CKD rat model transplanted with microbiota obtained from CKD patients exhibited accelerated CKD progression via increased production of trimethylamine N-oxide (TMAO), which was reversed by supplementation with extra butyrate. Our results showed that SCFA levels were reduced in CKD patients and that butyrate supplementation might delay CKD progression.
Abstract
In this paper, we propose a multimodal flexible sensory interface for interactively teaching soft robots to perform skilled locomotion using bare human hands. First, we develop a flexible ...bimodal smart skin (FBSS) based on triboelectric nanogenerator and liquid metal sensing that can perform simultaneous tactile and touchless sensing and distinguish these two modes in real time. With the FBSS, soft robots can react on their own to tactile and touchless stimuli. We then propose a distance control method that enabled humans to teach soft robots movements via bare hand-eye coordination. The results showed that participants can effectively teach a self-reacting soft continuum manipulator complex motions in three-dimensional space through a “shifting sensors and teaching” method within just a few minutes. The soft manipulator can repeat the human-taught motions and replay them at different speeds. Finally, we demonstrate that humans can easily teach the soft manipulator to complete specific tasks such as completing a pen-and-paper maze, taking a throat swab, and crossing a barrier to grasp an object. We envision that this user-friendly, non-programmable teaching method based on flexible multimodal sensory interfaces could broadly expand the domains in which humans interact with and utilize soft robots.
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