n a health management system, prognostics, which is an engineering discipline that predicts a system's future health, is an important aspect yet there is currently limited research in this field. In ...this paper, a hybrid approach for prognostics is proposed. The approach combines the least squares support vector regression (LSSVR) with the hidden Markov model (HMM). Features extracted from sensor signals are used to train HMMs, which represent different health levels. A LSSVR algorithm is used to predict the feature trends. The LSSVR training and prediction algorithms are modified by adding new data and deleting old data and the probabilities of the predicted features for each HMM are calculated based on forward or backward algorithms. Based on these probabilities, one can determine a system's future health state and estimate the remaining useful life (RUL). To evaluate the proposed approach, a test was carried out using bearing vibration signals. Simulation results show that the LSSVR/HMM approach can forecast faults long before they occur and can predict the RUL. Therefore, the LSSVR/HMM approach is very promising in the field of prognostics.
Co
3
O
4
has displayed promising ability for 5-hydroxymethylfurfural (HMF) electrooxidation reaction (HMFOR), which is an efficient way to produce high-value chemicals. However, its poor intrinsic ...ability has seriously limited its electrochemical performance. The introduction of foreign components into Co
3
O
4
via
heterophase interfacing is an efficient strategy to enhance its intrinsic activity. Herein, we have modified Co
3
O
4
through the fabrication of the heterophase interface between Cu-doped Co
3
O
4
(Cu−Co
3
O
4
) and CuO (Cu−Co
3
O
4
/CuO). With the introduction of Cu species, the electronic structure of the electrocatalyst has been well-modulated, whose electrons were preferentially transformed from Co to Cu atoms, suggesting a strong electron interaction. The electrochemical results suggest that Cu−Co
3
O
4
/CuO exhibited a lower overpotential, faster reaction kinetics, and higher turnover frequency than Cu−Co
3
O
4
and pure Co
3
O
4
. Experimental results and theoretical calculations demonstrate that the fabrication of the heterophase interface could have strong adsorption toward HMF owing to the enhanced interaction with the aldehyde and hydroxymethyl groups. Furthermore, Cu−Co
3
O
4
/CuO possessed a relatively poor reliance on the furan ring for HMF adsorption but accelerated the oxidation of the aldehyde group. This work provides a significant reference for the development of efficient HMFOR electrocatalysts.
Climate patterns, cropping systems, and agricultural technologies have greater diversity among various regions in China. Knowledge of the spatial–temporal patterns of solar radiation during the maize ...growing season is essential for farmers and extension technicians in their optimization of cropping choices and development of adaptation strategies for climate change. In this study, based on the observed solar radiation in six subregions of China, we analyzed the spatial distributions and temporal trends of incident solar radiation (SRi), beam solar radiation (SRb), and diffuse solar radiation (SRd) during 1961–2014. From 1961 to 1984, the annual SRi in most areas showed a downward trend, with a median value of −27.8 MJ m−2 year−1, which is primarily due to a decrease in SRb. However, after 1985, 76% of locations had reversed to brightening. This finding is primarily due to an increase in SRd. The trends in SRi during the whole growing season (WGS) of maize changed by −12.4% to 18.3% during the past 30 years, and 74% of the selected locations showed an increasing trend. At most of the stations, SRb showed a decreasing trend during the WGS, and SRd showed an increasing trend. The trends of SRi, SRb, and SRd during the vegetative period and reproductive period of maize have generally followed a trend similar to the WGSs. Therefore, we conclude that annual solar radiation changed from dimming to brightening from 1961 to 2014 in China. Solar brightening occurred during the maize growing season, which was mainly caused by an increase in diffuse radiation.
Crop yields are affected by many factors related to breeding, management, and climate. Understanding climate factors trends and possible impacts on yield trend is important to help ensure that these yield increases continue in the future. So the scientific question in this paper we are addressing is how the changes of solar radiation during the maize growing season during the past 5 decades?
Diagnosis of thyroid disease among individuals dwelling at high altitude remains a challenge. Reference intervals (RIs) for thyroid-associated hormones among Tibetans living at various high altitudes ...were established to improve diagnosis.
One thousand two hundred eighty-one subjects were randomly recruited from Nyingchi, Shigatse/Lhasa, and Ali of Tibet. Thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) were measured by the Cobas e601 electrochemiluminescence analyzer. We used multiple linear regression and variance component analysis to assess the effect of sex, age, and altitude on hormones. RIs were established by refineR algorithm and compared with those provided by the manufacturer.
Serum TSH was significantly lower in males than in females, while FT3 and FT4 were higher in males. Both FT3 and FT4 decreased with increasing age. FT3 increased with altitude, while TSH and FT4 were less influenced by altitude. The RI for TSH was 0.764-5.784 μIU/ml, while for FT4, the RIs were 12.36-19.38 pmol/L in females and 14.84-20.18 pmol/L in males. The RIs for FT3 at Nyingchi, Shigatse/Lhasa, and Ali in females were 4.09-4.98, 4.31-5.45, and 4.82-5.58 pmol/L, while in males, the values were 4.82-5.41, 4.88-5.95, and 5.26-6.06 pmol/L, respectively. The obtained RIs for TSH and FT4 were generally higher, while that for FT3 was narrower than the RIs provided by Cobas.
Specific RIs were established for thyroid-associated hormones among Tibetans, which were significantly different from those provided by the manufacturer.
The increased frequency of climate extremes associated with ongoing climate change has the potential for significant impacts on maize grain yield in maize-producing regions worldwide. In this study, ...we used a modeling approach to investigate the effects of different types of climatic extremes on maize grain yield in Northeast China. We combined annual mean air temperature and accumulated precipitation data and divided the climate years into 9 categories, using the 10th and 90th percentiles as extreme thresholds. The climate data were represented by 1 normal climate type, 4 individual climate extremes, and 4 combined climate extremes. Changes in the frequencies of climate extremes and their impacts on maize grain yields were analyzed for two 30-year periods (period I: 1960–1989; period II: 1990–2019) using the Agricultural Production Systems sIMulator (APSIM-Maize). Compared with period I, the occurrences of the normal climate and all 3 cold-related climate extremes (i.e., cold-normal, cold-humid, and cold-dry) decreased during period II, while occurrences of the other climate extremes increased. Moreover, according to the APSIM-Maize model, the estimated yield in the years with a normal climate decreased by 4.01%; the 3 cold-related climate extremes increased yields by 26.56%, 12.10%, and 6.68%, respectively; the 2 warm-related climate extremes (warm-normal and warm-dry) and normal-humid years decreased estimated yields by 6.39%, 24.12%, and 5.10%, respectively. The increase in the occurrence of warm-humid years increased the estimated yield by 11.69%. This work confirms the adverse effects of warmer temperatures in the absence of excess rainfall on grain yield and highlights the importance of extremely dry or wet conditions under normal temperature conditions.
Previous studies reported that the blood of Tibetans living at different altitudes may vary slightly. There is evidence that the harsh environmental conditions at high altitudes, such as low pressure ...and hypoxia, may affect the morphology and hemorheology of red blood cells (RBCs). Hypoxia would increase the levels of hemoglobin (Hb) and hematocrit (Hct), potentially increasing blood hyperviscosity and compromising blood collection and transfusions. Therefore, it is critical to investigate the
storage quality of Tibetan RBCs.
In this study, the
quality of suspended RBCs (SRBCs) prepared from whole blood (WB) of Tibetan residents with varying Hb concentrations (Hb) was measured during storage, and the relationship between the major factors in RBC storage and Hb was studied.
The WB of Tibetan men was divided into three groups based on Hb levels (group A: 120 < Hb ≤ 185 g/L; group B: 185 < Hb ≤ 210 g/L; group C: Hb > 210 g/L). The SRBCs prepared from WB were examined aseptically on days 1, 14, 21, and 35 after storage.
Hb was not correlated with mean corpuscular volume (MCV), adenosine triphosphate (ATP), pH, P50, and hemolysis. There was a moderate or strong negative association between platelets (PLT) and Hb from days 1 to 35, and the PLT number of group C was lower than group A during storage. Group C had the highest change rates of electrolytes, glucose, and lactate, and there were moderate or strong positive correlations between lactate and Hb (
= 0.3772,
= 0.0045), glucose and Hb (
= 0.5845,
< 0.0001), Na
and Hb (
= 0.3966,
= 0.0027), and K
and Hb (
= 0.4885,
= 0.0002). Group B had the highest change rates of 2,3-DPG on day 35, and there was a negative correlation between 2,3-DPG and Hb (
= -0.4933,
= 0.0001).
These new data on the Hb could have implications for researchers wishing to study the storage quality of Tibetan SRBCs, particularly in the context of erythrocyte metabolism, and we propose finding a new, suitable alternative solution for plateau SRBCs, particularly the blood with Hb greater than 185 g/L. Our results could have important implications for researchers wishing to study the potential framework of high-altitude-induced SRBC storage lesions.
Grassland transfer is an important management tool for the development of animal husbandry, yet the factors affecting herdsmen’s grassland transfer activity have seldom been investigated. This study ...analyzes the factors affecting grassland transfer in Hulunbuir and Xilingol, Inner Mongolia, China, using a multinomial logistic regression model. The results suggest that the educational level of the head of the household, their position as a leader of the village, the form of grassland transfer contract, distance from village to town, and height of forage grass have significant effects on the practice of grassland transfer. The quantity of livestock, grassland area per capita, income from animal husbandry as a proportion of total household income, and period of contract for grassland transfer are the main factors affecting grassland inflow, while the number of laborers has a great influence on grassland outflow. As a result, households actively engaged in livestock management tend to borrow more grassland, while households facing labor shortages tend to lend out their grasslands, thereby entailing adjustments to grassland area based on the household management situation. The results also imply that while these land transfers contribute to balancing livestock and grass on grasslands, transfer contracts and human resources must be further developed.
Layered double hydroxides (LDHs) with two‐dimensional lamellar structures show excellent electrocatalytic properties. However, the catalytic activity of LDHs needs to be further improved as the large ...lateral size and thickness of the bulk material limit the number of exposed active sites. However, the development of efficient strategies to exfoliate bulk LDHs into stable monolayer LDH nanosheets with more exposed active sites is very challenging. On the other hand, the intrinsic activity of monolayer LDH nanosheets can be tuned by surface engineering. Herein, we have exfoliated bulk CoFe LDHs into ultrathin LDH nanosheets through Ar plasma etching, which also resulted in the formation of multiple vacancies (including O, Co, and Fe vacancies) in the ultrathin 2D nanosheets. Owing to their ultrathin 2D structure, the LDH nanosheets expose a greater number of active sites, and the multiple vacancies significantly improve the intrinsic activity in the oxygen evolution reaction (OER).
Thinner and thinner: The dry exfoliation of bulk CoFe layered double hydroxides into ultrathin nanosheets with multiple vacancies was achieved by argon plasma etching to disrupt the intrinsic interlayer electrostatic interactions. These nanosheets are superior electrocatalysts for the oxygen evolution reaction.
Direct formic acid fuel cell (DFAFC) has been considered as a promising energy conversion device for stationary and mobile applications. Advanced platinum (Pt) electrocatalysts for formic acid ...oxidation reaction (FAOR) are critical for DFAFC. However, the oxidation of formic acid on Pt catalysts often occurs via a dual pathway mechanism, which hinders the catalytic activity owing to the CO poisoning. Herein, we directly exfoliate bulk antimony to 2D antimonene (Sb) and
load Pt nanoparticles onto antimonene sheets with the assistance of ethylenediamine. According to the Bader charge analysis, the charge transfer from antimonene to Pt occurs, confirming the electronic interaction between Pt and Sb. Interestingly, antimonene, as a cocatalyst, alters the oxidation pathway for FAOR over Pt catalyst and makes FAOR follow the more efficient dehydrogenation pathway. The density functional theory (DFT) calculation demonstrates that antimonene can activate Pt to be a lower oxidative state and facilitate the oxidation of HCOOH into CO
via a direct pathway, resulting in a weakened intermediate binding strength and better CO tolerance for FAOR. The specific activity of FAOR on Pt/Sb is 4.5 times, and the mass activity is 2.6 times higher than the conventional Pt/C.
MgCo2O4, CoCr2O4, and Co2TiO4 were selected, where only Co3+ in the center of octahedron (Oh), Co2+ in the center of tetrahedron (Td), and Co2+ in the center of Oh, can be active sites for the oxygen ...evolution reaction (OER). Co3+(Oh) sites are the best geometrical configuration for OER. Co2+(Oh) sites exhibit better activity than Co2+(Td). Calculations demonstrate the conversion of O* into OOH* is the rate‐determining step for Co3+(Oh) and Co2+(Td). For Co2+(Oh), it is thermodynamically favorable for the formation of OOH* but difficult for the desorption of O2. Co3+(Oh) needs to increase the lowest Gibbs free energy over Co2+(Oh) and Co2+(Td), which contributes to the best activity. The coexistence of Co3+(Oh) and Co2+(Td) in Co3O4 can promote the formation of OOH* and decrease the free‐energy barrier. This work screens out the optimal geometrical configuration of cobalt cations for OER and gives a valuable principle to design efficient electrocatalysts.
MgCo2O4, CoCr2O4, and Co2TiO4 were selected, where only Co3+ in the center of octahedron (Oh), Co2+ in the center of tetrahedron (Td), and Co2+ in the center of Oh can be active sites as model electrocatalysts for the oxygen evolution reaction. Co3+(Oh) sites are the best geometrical configuration; Co2+(Oh) sites exhibit better electrochemical activity than Co2+(Td).
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