A fundamental problem in control systems theory is that stability is not always guaranteed for a closed-loop system even if the plant is open-loop stable. With the only knowledge of the ...input-to-state (practical) stability (ISpS) of the plant, in this note, a bounded integral controller (BIC) is proposed which generates a bounded control output independently from the plant parameters and states and guarantees closed-loop system stability in the sense of boundedness. When a given bound is required for the control output, an analytic selection of the BIC parameters is proposed and its performance is investigated using Lyapunov methods, extending the result for locally ISpS plant systems. Additionally, it is shown that the BIC can replace the traditional integral controller (IC) and guarantee asymptotic stability of the desired equilibrium point under certain conditions, with a guaranteed bound for the solution of the closed-loop system. Simulation results of a DC/DC buck-boost power converter system are provided to compare the BIC with the IC operation.
•LaFe11.6Si1.4/Pr2Co7 composites were fabricated by SPS followed by annealing.•10 wt% Pr2Co7 addition and medium LaFe11.6Si1.4 powders were conducive to 1:13 phase formation.•The diffusion of Pr/Co ...into the 1:13 phase improves the TC of these composites.•The composites exhibit excellent (σbc)max of 930–1405 MPa and λ of 14–20.90 W/m∙K.•These composites are promising candidates for near RT cooling applications.
A series of LaFe11.6Si1.4/xwt%Pr2Co7 (x = 0, 5, 10) composites, with a range of particle size of LaFe11.6Si1.4 powders, were successfully fabricated by spark plasma sintering (SPS), followed by annealing. The influence of the particle size of the LaFe11.6Si1.4 powders and the Pr2Co7 binder content on the phase constitution, microstructure, thermal, mechanical, magnetic and magnetocaloric properties were studied. The Pr2Co7 binder content (10 wt%) and the particle size of LaFe11.6Si1.4 powders (100–200 µm) were chosen to be conducive to the formation of the desired 1:13 phase. The magnetic and magnetocaloric properties were influenced by the synergistic effects of Pr and Co atomic diffusion as well by the particle size of the LaFe11.6Si1.4 majority phase powders. The values of TC, (ΔSM)max and RC for the sample could be tuned in the range of 230–297 K, 1.90–3.70 J/kg·K and 84–149 J/kg (ΔH=2 T), respectively, by tuning the Pr2Co7 content and the particle size of the LaFe11.6Si1.4 powders. Significantly, this TC range covers a wide variety of near room temperature cooling applications. The excellent values of thermal conductivity, maximum compressive strength and strain were in the range of 14–20.90 W/m·K, 930–1405 MPa and 5.9–7.9%, respectively. These features make these materials very promising candidates for near room temperature magnetic cooling applications.
We studied the impacts of anthropogenic changes in land use on the stoichiometric imbalance of soil carbon (C), nitrogen (N), phosphorus (P) and potassium (K) in Phragmites australis wetlands in the ...Minjiang River estuary. We compared five areas with different land uses: P. australis wetland (control), grassland, a mudskipper breeding flat, pond aquaculture and rice cropland. Human activity has affected the elemental and stoichiometric compositions of soils through changes in land use. In general, soil C and N concentrations were lower and total soil K concentrations were higher at the sites under human land uses relative to the control site, and total soil P concentrations were generally not significantly different. The close relationship between total soil C and N concentrations in all cases, including fertilization with N, suggested that N was the most limiting nutrient in these wetlands. Lower soil N concentrations and similar soil P concentrations and higher soil K concentrations under human land-use activities suggest that human activity has increased the role of N limitation in these wetlands. Only grassland use increases soil N contents (only in the 0–10cm of soil). Despite N fertilization, lower soil N concentrations were also observed in the rice cropland, indicating the difficulty of avoiding N limitation in these wetlands. The observed lower soil N:P ratio, together with higher soil P and K availabilities in rice croplands, is consistent with the tendency of human activity to change the competitive relationships of plants, in this case favoring species adapted to high rates of growth (low N:P ratio) and/or favoring plants with high demands for P and K. Both, soil C storage and respiration were higher in grasslands, likely due to the introduction of grasses, which led to a high density of plants, increased grazing activity and soil compaction. Soil C storage and respiration were lower under human land uses, except in the rice cropland, with respect to natural wetland. Using overall data, soil C storage and respiration were correlated, indicating that soil respiration was correlated with plant productivity. In this wetland area the impacts of different human land-uses on soil stoichiometry and C-cycle can be very different depending on the activity. Further regeneration of natural communities can be determined by the previous type of land-use.
•Human activity increases total soil K and available-P concentrations.•Despite low soil N:P ratio, human activities decrease even more the soil N:P ratios.•These decreases of soil N:P are linked with the presence of high growth rate species.•Human activities decrease soil C and N concentrations affecting C storing capacity.•These soil stoichiometry changes can influence the regeneration of natural vegetation.
A new regime in the interaction of a two-color (ω,2ω) laser with a nanometer-scale foil is identified, resulting in the emission of extremely intense, isolated attosecond pulses-even in the case of ...multicycle lasers. For foils irradiated by lasers exceeding the blow-out field strength (i.e., capable of fully separating electrons from the ion background), the addition of a second harmonic field results in the stabilization of the foil up to the blow-out intensity. This is then followed by a sharp transition to transparency that essentially occurs in a single optical cycle. During the transition cycle, a dense, nanometer-scale electron bunch is accelerated to relativistic velocities and emits a single, strong attosecond pulse with a peak intensity approaching that of the laser field.
Objectives
The impact of electrolyte imbalance on clinical outcomes after acute ischemic stroke (AIS) is still not understood. We investigated the association between hypochloremia and hyponatremia ...upon hospital admission and in‐hospital mortality in AIS patients.
Materials and methods
A total of 3314 AIS patients enrolled from December 2013 to May 2014 across 22 hospitals in Suzhou city were included in this study. Hypochloremia was defined as having a serum chloride concentration <98 mmol/L and hyponatremia as having a serum sodium concentration <135 mmol/L. The Cox proportional hazard model was used to examine the effect of hypochloremia and hyponatremia on all‐cause in‐hospital mortality in AIS patients.
Results
During hospitalization, 118 patients (3.6%) died from all causes. Multivariable model adjusted for age, sex, baseline National Institutes of Health Stroke Scale score, serum sodium, and other potential covariates showed that hypochloremia was associated with a 2.43‐fold increase in the risk of in‐hospital mortality (hazard ratio HR 2.43; 95% confidence interval CI, 1.41‐4.19; P=.001). However, no significant association between hyponatremia (P=.905) and in‐hospital mortality was observed. Moreover, the multivariable analysis found that serum chloride (HR=0.92, 95% CI 0.88‐0.98; P=.004) but not serum sodium (P=.102) was significantly associated with in‐hospital mortality.
Conclusions
Hypochloremia at admission was independently associated with in‐hospital mortality in AIS patients.
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•High density La-Fe-Si based composites were fabricated by short time SPS followed by annealing.•The magnetocaloric and mechanical properties could be tuned by changing the SPS ...temperature.•The optimum process was SPS@1273 K/5min followed by annealing@1323 K/24 h.•Excellent (σbc)max ∼ 1GPa, λ ∼ 17.68 W/m∙K and large (−ΔSM)max ∼ 2.3 J/kg‧K@2T were obtained.
La(Fe,Si)13 based magnetocaloric composites were prepared by spark plasma sintering (SPS), followed by annealing. The microstructure, mechanical and magnetocaloric properties were investigated. With increasing SPS temperature (TSPS) below 1373 K, the content of (La,Pr)(Fe,Co,Si)13 majority phase increased, while the content of minority phase α-Fe decreased. The increase of TSPS from 973 K to 1373 K greatly improved the composite density, and the density sharply increased from ∼ 68 % to 98 %. After SPS at 1273 K/5 min followed by 1323 K/24 h annealing, high content of 89.35 wt% of the desired (La,Pr)(Fe,Co,Si)13 phase was obtained in LaFe11.6Si1.4/10wt%Pr2Co7 composites. A large increase of Curie temperature (TC) from 196 K to 297 K was observed. The maximum magnetic entropy change (−ΔSM)max reached 2.3 J/(kg‧K) under 2 T magnetic field. ∼ 97 % of full density, excellent compressive strength of ∼ 1GPa and high thermal conductivity of 17.68 W/m∙K were exhibited. Thus, a route to produce high density La-Fe-Si based magnetocaloric composites with excellent mechanical properties and thermal conductivity, good (−ΔSM)max and adjustable TC by short time spark plasma sintering followed by annealing was demonstrated.
Large-scale CuO nanowires were in situ grown on Cu substrate by a very simple catalyst-free thermal oxidation process in atmosphere. The structure characterization revealed that these nanowires are ...monoclinic structured single crystallites with mean diameters of 60–200
nm. The effects of growth time and temperature on the morphology of the nanowires were investigated. It is found that the growth time has an important effect on the length and density of the nanowires, whereas the growth temperature has a distinct influence on the nanowire diameter. Different from the vapor–solid (V–S) mechanism, the growth of nanowires is found to be based on the Cu ion diffusion. The ethanol-sensing properties of these CuO nanowires were also studied based on a self-designed prototype and the results indicated that these large-scale nanowires are indeed a good candidate for gas-sensing applications.
Primary antibody deficiencies (PAD) are a group of congenital disorders caused by genetic defects that affect the development and function of the body's immune defence mechanisms. Patients with PAD ...may present with recurrent infections, lymphoproliferation, autoimmune diseases, autoinflammation, or malignancies. Respiratory system manifestations may include bronchiectasis, bronchial asthma, and interstitial lung disease, among others. A comprehensive understanding of PADs will help to distinguish these covert cases from more common respiratory diseases.
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