Intermittent Strategy Research Articles

Enhanced Electromagnetic Shielding and Thermal Management Properties in MXene/Aramid Nanofiber Films Fabricated by Intermittent Filtration

High-efficiency electromagnetic interference (EMI) shielding and heat dissipation synergy materials with flexible, robust, and environmental stability are urgently demanded in next-generation integration electronic devices. In this work, we report the lamellar MXene/Aramid nanofiber (ANF) composite films, which establish a nacre-like structure for EMI shielding and heat dissipation by using the intermittent filtration strategy. The MXene/ANF composite film filled with 50 wt % MXene demonstrates enhanced mechanical properties with a strength of 230.5 MPa, an elongation at break of 6.2%, and a toughness of 11.8 MJ·m3 (50 wt % MXene). These remarkable properties are attributed to the hydrogen bonding and highly oriented structure. Furthermore, due to the formation of the MXene conductive network, the MXene/ANF composite film shows an outstanding conductivity of 624.6 S/cm, an EMI shielding effectiveness (EMI SE) of 44.0 dB, and a superior specific SE value (SSE/t) of 18847.6 dB·cm2/g, which is better than the vacuum filtration film. Moreover, the MXene/ANF composite film also shows a great thermal conductivity of 0.43 W/m·K. The multifunctional MXene/ANF composite films with high-performance EMI shielding, heat dissipation, and joule heating show great potential in the field of aerospace, military, microelectronics, microcircuit, and smart wearable electronics.

Organic media-based two-stage traditional and electrode-integrated tidal flow wetlands to treat landfill leachate: Influence of aeration strategy and plants

Landfill leachate treatment employing normal and electrode-integrated constructed wetlands is difficult due to the presence of significant amounts of organic compounds, which frequently impede the progression of microbial-based aerobic pollutant removal pathways. As a result, this study examines the effect of supplementary air availability via intermittent and continuous aeration strategies in improving organic, nutrient, and coliform removals of the unplanted, planted (normal and electrode-integrated) two-stage tidal flow constructed wetlands designed to treat landfill leachate. The constructed wetlands were filled with coal and biochar media and planted with Canna indica. Mean chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), and coliform removal percentages of the externally aerated two-stage unplanted, only planted, planted-microbial fuel cell integrated constructed wetland systems ranged between 96 and 99%, 82 and 93%, 91 and 98%, 86 and 96%, respectively, throughout the experimental campaign. External aeration inhibited the development of a dominant anaerobic environment within the media of the wetland systems and improved overall pollutant removal. The electrode-integrated planted tidal flow wetlands produced better effluent quality than the unplanted or only planted tidal flow systems without electrode assistance. The first stages of the three wetland systems achieved an additional 5–7% COD, 7–12% TN, and 15–22% coliform removal during the continuous aeration period compared to the corresponding performance of the intermittent aeration phase. The pollutant removal performance of the second-stage wetlands decreased during the continuous aeration phase. The media composition supported electrochemically active and inactive microbial-based pollutant removal routes and the chemical adsorption of pollutants. Nitrogen and phosphorus accumulation percentage in plant tissues was low, i.e., 0.4–2.2% and 0.04–0.8%, respectively. During the continuous aeration period, the electrode-integrated tidal flow constructed wetlands achieved higher power density production, i.e., between 859 and 1432 mW (mW)/meter3(m3). This study demonstrates that external aeration might improve pollutant removal performance of the normal, electrodes integrated tidal flow-based constructed wetlands when employed for high organic-strength wastewater treatment such as landfill leachate.

Intermittent energization improves microbial electrolysis cell-assisted thermophilic anaerobic co-digestion of food waste and spent mushroom substance

Microbial electrolysis cell-assisted thermophilic anaerobic digestion (MEC-TAD) is a promising method to improve anaerobic co-digestion efficiency; however, its application is restricted by high energy consumption. To improve the energy use efficiency of MEC-TAD, this study investigated the effect of different intermittent energization strategies on thermophilic co-digestion performance. Results revealed that an 18 h-ON/6h-OFF energization schedule resulted in the fastest electron transfer rate and the highest methane yield (364.3 mL/g VS). Mechanistic analysis revealed that 18 h-ON/6h-OFF resulted in the enrichment of electroactive microorganisms and increased abundance of enzyme-coding genes associated with energy metabolism (ntp, nuo, atp), electron transfer (pilA, nfrA2, ssuE), and the hydrogenotrophic methanogenic pathway. Finally, energy balance analysis revealed that 18 h-ON/6h-OFF had the highest net energy benefit (2.52 kJ) and energy conversion efficiency (110.76 %). Therefore, intermittent energization of MEC-TAD using an 18 h-ON/6h-OFF schedule can provide improved performance and more energy savings.

Temporal-Intermittent-Spatio-Sampling Control for Stochastic Switched RDNNs With Impulsive Effects

This brief mainly investigates the stabilization problem for a class of state-dependent switched reaction-diffusion neural networks (RDNNs) with stochastic disturbance and impulsive effects. First, a hybrid control strategy of time domain intermittent-spatial domain point sampling is proposed, which can greatly reduce the control cost. Then, by using the constructed multi-partition Lyapunov function and the convex combination method, two different stabilization criteria are derived for the target system with stabilizing impulse and destabilizing impulse, which are shown in the form of easy-to-calculate LMIs. Moreover, the multi-gain phenomenon is effectively avoided through the single decision-multivariable technique, which facilitates the operation of the actual system. Note that our results are more practical than those established only on pure stabilizing impulse and destabilizing impulse. Particularly, one of the results shows that even if the switched RDNN with destabilizing impulse is unstable, it can be stabilized by the hybrid intermittent sampling control strategy proposed in this brief. Finally, numerical examples show the rationality and validity of the new results.

Efficient co-production of fermentable sugars and biobutanol from corn stover based on a novel butyric acid pretreatment strategy

Efficient deconstruction of lignocellulosic biomass by pretreatment is important for the production of fermentable sugars and biofuels. This study used butyric acid as a novel catalyst for corn stover pretreatment. The effects of butyric acid pretreatments on chemical composition and enzymatic digestibility were systematically investigated. The results indicate that a high linear correlation between xylan removal and fermentable sugars yield (r2 = 0.91) was found. Pretreatment of corn stover with 50 g/L butyric acid at 180 °C for 0.5 h removed 83.17% of xylan and recovered 86.99% of glucan, and fermentable sugars yield of pretreated corn stover reached 97.16%. The physiochemical characterization results show that crystalline index (CrI) of corn stover was increased from 30.13% to 45.04%−48.38% after pretreatments, and the chemical structure and morphological features also exhibited positive changes for enhancing enzymatic hydrolysis. Meanwhile, the liquid fraction of pretreated slurry can be used for recycled pretreatment with 73.81% of fermentable sugars yield after four cycles. Additionally, the residual butyric acid was re-utilized as the co-substrate for Clostridium acetobutylicum ATCC 824 to produce biobutanol via acetone-butanol-ethanol (ABE) fermentation. The final production of butanol and solvents reached 8.38 g/L and 12.63 g/L under an optimized intermittent feeding strategy with a higher butanol/acetone ratio of 2.40 g/g. Overall, this work presents a novel pretreatment strategy to co-produce fermentable sugars and advanced biofuel from abundant lignocellulosic biomass.

Assessment of the efficiency of intermittent and continuous walking strategies in hypoxia

Assessment of the efficiency of intermittent and continuous walking strategies in hypoxia

Aperiodically Intermittent Control Strategy and Adaptive Synchronization of Neural Networks With Inertial and Memristive Terms

Aperiodically Intermittent Control Strategy and Adaptive Synchronization of Neural Networks With Inertial and Memristive Terms

In overweight and obese patients, is there an intermittent fasting strategy which results in the greatest weight reduction?

In overweight and obese patients, is there an intermittent fasting strategy which results in the greatest weight reduction?

Bipartite consensus for multi-agent networks of fractional diffusion PDEs via aperiodically intermittent boundary control.

In this paper, the exponential bipartite consensus issue is investigated for multi-agent networks, whose dynamic is characterized by fractional diffusion partial differential equations (PDEs). The main contribution is that a novel exponential convergence principle is proposed for networks of fractional PDEs via aperiodically intermittent control scheme. First, under the aperiodically intermittent control strategy, an exponential convergence principle is developed for continuously differentiable function. Second, on the basis of the proposed convergence principle and the designed intermittent boundary control protocol, the exponential bipartite consensus condition is addressed in the form of linear matrix inequalities (LMIs). Compared with the existing works, the result of the exponential intermittent consensus presented in this paper is applied to the networks of PDEs. Finally, the high-speed aerospace vehicle model is applied to verify the effectiveness of the control protocol.

Event-triggered aperiodic intermittent sliding-mode control for master–slave bilateral teleoperation robotic systems

PurposeThe purpose of this paper is to propose a novel event-triggered aperiodic intermittent sliding-mode control (ETAI-SMC) algorithm for master–slave bilateral teleoperation robotic systems to further save communication resources while maintaining synchronization precision.Design/methodology/approachBy using the Lyapunov theory, a new event-triggered aperiodic intermittent sliding-mode controller is designed to synchronize master–slave robots in a discontinuous method. Unlike traditional periodic time-triggered continuous control strategy, a new ETAI condition is discussed for less communication pressure. Then, the exponential reaching law is adopted to accelerate sliding-mode variables convergence, which has a significant effect on synchronization performance. In addition, the authors use quantizers to make their algorithm have obvious progress in saving communication resources.FindingsThe proposed control algorithm performance is validated by an experiment developed on a practical bilateral teleoperation system with two PHANToM Omni robotic devices. As a result, the synchronization error is limited within a small range and the control frequency is evidently reduced. Compared with a conventional control algorithm, the experimental results illustrate that the proposed control algorithm is more sensitive to system states changes and it can further save communication resources while guaranteeing the system synchronization accuracy, which is more practical for real bilateral teleoperation robotic systems.Originality/valueA novel ETAI-SMC for bilateral teleoperation robotic systems is proposed to find a balance between reducing the control frequency and synchronization control precision. Combining the traditional sliding-mode control algorithm with the periodic intermittent control strategy and the event-triggered control strategy has produced obvious effect on our control performance. The proposed ETAI-SMC algorithm helps the controller be more sensitive to system states changes, which makes it possible to achieve precise control with lower control frequency. Moreover, we design an environment contact force feedback algorithm for operators to improve the perception of the slave robot working environment. In addition, quantizers and the exponential convergence law are adopted to help the proposed algorithm perform better in saving communication resources and improving synchronization precision.

Nitrification kinetics, N2O emission, and energy use in intermittently aerated hybrid reactor under different organic loading rates

This study investigated the impact of intermittent aeration strategies and reduction in the reactor’s organic and nitrogen loading rates on the course of particular stages of the nitrification process, as well as energy consumption and N2O emissions in a hybrid reactor with nitrification/denitrification. Each of the analysed series revealed the greatest ammonia oxidation activity in activated sludge flocs. The highest activity of nitrite nitrogen oxidation was demonstrated in the case of biofilm. A reduction in the reactor’s organic and nitrogen loading rate value had a greater effect on changes in the activity of ammonia-oxidizing bacteria than nitrite-oxidizing bacteria. In a system where the operation of air pumps was controlled through switching them and off according to the adopted ratio between non-aerated and aerated sub-phase times and the assumed oxygen concentration, a reduction in the duration of aerated sub-phases caused no decrease in energy use for aeration. Lower N2O emission was recorded when the reactor operated with a longer duration of aerated sub-phases.

1986. Multicenter evaluation of Staphylococcus aureus prosthetic valve infective endocarditis with and without gentamicin treatment: Is it time to revisit?

Abstract Background Staphylococcus aureus prosthetic valve infective endocarditis (SA-PVIE) is associated with high mortality. Gentamicin (GEN) with anti-staphylococcal antibiotics and rifampin are guideline recommendations for SA-PVIE extrapolated from in vitro data. GEN can lead to acute kidney injury (AKI), meanwhile, the clinical benefit on infection-related outcomes remains unclear. Therefore, we evaluated the impact of GEN on outcomes in SA-PVIE. Methods This is a multicenter, retrospective cohort conducted at HonorHealth and UCHealth systems. Adults admitted between January 2014-2022 with definite/possible SA-PVIE by Duke Criteria were included if they received ≥2 days of treatment within 2 days of index culture. Cohorts were stratified by GEN receipt. The primary outcome was 90-day all-cause mortality. The secondary outcomes were treatment failure (change in antimicrobials, abscess development, new indication for cardiac surgery), 30-day all-cause mortality, and incidence of AKI by KDIGO Criteria. Results Overall, 38 patients with definite (40%) and possible SA-PVIE (60%) met inclusion (13 GEN, 25 without GEN [no-GEN]). At baseline, 15 (40%) patients were in an ICU, median Pitt bacteremia score was 2, and methicillin-susceptible S. aureus predominated (71%). A total of 10 (26%) patients had valve surgery; median bacteremia duration was similar between GEN and no-GEN (4 vs 3 days, p = 0.26). Common antibiotics were vancomycin (95%), cefazolin (63%), and nafcillin (21%); rifampin was more common in GEN than no-GEN (20% vs 77%, p < 0.001). Baseline AKI (44% vs 46%) and renal impairment (8% vs 0%) were not different between GEN and no-GEN, respectively. GEN was initiated a median 3 days after index culture, most commonly as intermittent strategy (69%) with 3 mg/kg daily equivalent (84.6%). There was no statistical difference in treatment failure (23% vs 24%, p=0.17), 30-day mortality (20% vs 39%, p=0.22), or 90-day mortality (28% vs 43%, p=0.263) between GEN and no-GEN, respectively. Three in the (23%) GEN group experienced AKI, compared to 10 (40%) in no-GEN. Conclusion We did not find that the addition of GEN to SA-PVIE therapy enhanced mortality benefit, yet patients without GEN may live to experience adverse events. Further studies were warranted. Disclosures All Authors: No reported disclosures.

Teor e acúmulo de nutrientes em mini alface em função de estratégias de manejo de fertirrigação

ABSTRACT Determining the amount of nutrients accumulated by crops is an important tool for defining the order in which nutrients are taken up and required. However, the order and amount of accumulated nutrients vary depending on the genetic characteristics of the cultivars, climatic conditions, fertilization, soil and management systems. The aim of this study was to evaluate the influence of irrigation management strategies and doses of nitrogen (N) fertigation on the content and accumulation of macro and micronutrients and the N use efficiency in mini romaine lettuce “Astorga” cultivated in a protected environment, in two consecutive crop cycles. The treatments consisted of three irrigation strategies: continuous irrigation (Cont), intermittent irrigation, with three fractions a day, at 1-hour intervals (Int1); intermittent irrigation, with three fractions a day, at 4-hour intervals (Int2) and two nitrogen doses (100 and 130 kg/ha N), in daily fertigation. Intermittent irrigation management strategies (Int1 and Int2) increased the contents and accumulation of dry matter and N, P, K, Ca, Mg, S, B, Fe, Mn and Zn. The dose of 130 kg/ha N only increased the content and accumulation of P and Mn in the first and second cycles, respectively. In general, lettuce accumulated macronutrients in the following decreasing order: K>N>Ca>P>Mg>S, whereas micronutrients followed the order Fe>Mn>Zn>B>Cu. The treatments Int1, Int2 and 100 kg/ha N optimized the N use efficiency.

Intermittent Cluster Consensus Control of Multiagent Systems From a Static/Dynamic Output Approach

This article is concerned with the cluster consensus control problem for multiagent linear systems with a directed communication topology, where only relative output measurements of neighboring agents are available to each agent. Motivated by the pinning control technique, both static and dynamic intermittent output control strategies are proposed. Using Lyapunov functions, sufficient conditions are developed to ensure cluster consensus with existence-guaranteed control parameters. Both periodic and nonperiodic operations of intermittent controllers are investigated. Finally, the effectiveness of the theoretical results is demonstrated by a simulation example.

Multiple leaders formation tracking with switching topology and aperiodic sampled data under intermittent control scheme

AbstractThis article studies the problem of second‐order formation tracking with multiple leaders under intermittent control scheme in stochastic multi‐agent networked systems. Based on the aperiodic sampled data, the formation tracking control protocol is proposed by considering switching topology and the time‐varying transmission delay of information interaction between each agent. Using the algebraic graph theory, stochastic systems theory, Lyapunov theory, and Halanay inequality, the sufficient conditions of mean square stability for formation tracking with multiple leaders are obtained. To further alleviate the computation resources of the controller, the intermittent control strategy is proposed. Meanwhile, a novel stability analysis method for intermittent control is introduced based on an auxiliary system and comparison principle. Furthermore, the lower bound of the duty cycle for a certain control period is obtained and the desired formation mode is also reached under the designed intermittent control scheme. Finally, numerical examples are given to verify the correctness and effectiveness of the proposed methods.

Stability of stochastic delayed multi-links complex network with semi-Markov switched topology: A time-varying hybrid aperiodically intermittent control strategy

This paper is concerned with the stability analysis of stochastic delayed multi-links complex networks with semi-Markov switched topology (SDMNST). It ought to be highlighted that a time-varying hybrid aperiodically intermittent control (THAIC) strategy, that the control gain is a sign-indefinite function and can be unbounded, is proposed. In the light of a major consideration for both stabilizing control and destabilizing input, the THAIC is capable of being manipulated to a wider range of intermittent control signals. Meanwhile, our proposed control strategy can not only deal with the problem that the intermittent control signals subject to external interferences, but also effectively avoid the possible damage of actuators caused by the sudden and rapid switching of control gain from a negative constant value to zero. The concept “average intermittent control gain” is introduced to quantify the gain of THAIC. As a generalization of the existing Halanay-type inequalities, several novel differential inequalities with time-varying and unbounded coefficients are established, based on which and Lyapunov method as well as graph theory, less conservative stability criteria of SDMNST are rigorously demonstrated. Subsequently, the theoretical results are applied to spring-mass-damper systems and numerical simulations are exploited with the design of control gain being shown.

Synchronization of nonlinear coupled complex network via event-dependent intermittent pinning control

This paper addresses the synchronization problem of nonlinear coupled complex network via event-dependent aperiodically intermittent pinning control. The regional division based event-dependent intermittent control strategy is established, which relies on the relationship between the subregion and Lyapunov function. By imposing event-dependent linear and adaptive intermittent controllers to partial nodes respectively, some sufficient conditions are developed to ensure achieving pinning synchronization. The Zeno behavior is excluded for the proposed event-dependent mechanism. Two numerical examples are presented to verify the effectiveness of the theoretical results.

Asynchronous Intermittent Regulation of Human Arm Movement with Markovian Jumping Parameters.

In this paper, the regulation stability problem of the human arm continuous movement is investigated based on Markovian jumping parameters. In particular, the intermittent control mechanism is adopted in the arm movement regulation procedure to model the human intermittent motor control strategy. Furthermore, by taking into account the Markovian jumping parameters with different modes, the asynchronous regulation issue is proposed to model mode mismatch between the motor control and arm movement. On the basis of model transformation, sufficient stability conditions are established during the arm movements, and the desired regulation gain can be obtained by the convex optimization method. In the end, an illustrative example is presented to show the applicability and effectiveness of our developed model and optimized regulation approach.

Optimization of bacterial cellulose production from alcohol lees by intermittent feeding strategy

Optimization of bacterial cellulose production from alcohol lees by intermittent feeding strategy

Effects of mixed-cooling strategies on executive functions in simulated tennis in hot and humid conditions.

This study aimed to investigate the effects of mixed-cooling strategies, which combines external (cooling vest + neck cooled collar) and internal cooling (cold sports drink ingestion) on measures of executive function during simulated tennis in hot/humid conditions. In a counterbalanced design (randomised order), eight males undertook two trials [one with the mixed-cooling strategy, (MCOOL condition) and another without (CON condition)] in a climate chamber (36.5°C, 50% relative humidity). All subjects completed an intermittent treadmill protocol simulating a three-set tennis match with a 90-second break during odd-numbered games and 120-second breaks between sets, in accordance with the activity profile and International Tennis Federation rules. The mixed-cooling strategies were adopted before test and break time during the simulated tennis match. Stroop task, 2-back task, More-odd shifting task, gastrointestinal temperature (Tgi), skin temperature, blood lactic acid (BLA), heart rate, urine specific gravity (USG), sweat rate (SR), thermal sensation (TS) and perceived exertion (RPE) were measured. Results showed that the mean exercise time was longer in the MCOOL condition than in the CON condition. The SR was greater in CON trial compared with that in MCOOL trial. Results of two-way analysis of variance with repeated measures revealed that time×condition interactions were significant in BLA, Stroop response time, and switch cost of the more-odd shifting task. There were main effects of condition for Tgi, HR, TS, RPE, BLA, Stroop response time, and switch cost of the more-odd shifting task. In a hot/wet environment, pre- and intermittent mixed-cooling strategies can significantly improve exercise time and measures of executive function of tennis players in a simulated tennis match.