Litter decomposition is key to ecosystem carbon(C)and nutrient cycling,but this process is anticipated to weaken due to projected more extensive and prolonged drought.Yet how litter quality and decomposer community co...Litter decomposition is key to ecosystem carbon(C)and nutrient cycling,but this process is anticipated to weaken due to projected more extensive and prolonged drought.Yet how litter quality and decomposer community complexity regulate decomposition in response to drought is less understood.Here,in a five-year manipulative drought experiment in a Masson pine forest,leaf litter from four subtropical tree species(Quercus griffthii Hook.f.&Thomson ex Miq.,Acacia mangium Willd.,Pinus massoniana Lamb.,Castanopsis hystrix Miq.)representing different qualities was decomposed for 350 d in litterbags of three different mesh sizes(i.e.,0.05,1,and 5 mm),respectively,under natural conditions and a 50%throughfall rain exclusion treatment.Litterbags of increasing mesh sizes discriminate decomposer communities(i.e.,microorganisms,microorganisms and mesofauna,microorganisms and meso-and macrofauna)that access the litter and represent an increasing complexity.The amount of litter C and nitrogen(N)loss,and changes in their ratio(C/N_(loss)),as well as small and medium-sized decomposers including microorganisms,nematodes,and arthropods,were investigated.We found that drought did not affect C and N loss but decreased C/N_(loss)(i.e.,decomposer N use efficiency)of leaf litter irrespective of litter quality and decomposer complexity.However,changes in the C/N_(loss)and the drought effect on C loss were both dependent on litter quality,while drought and decomposer complexity interactively affected litter C and N loss.Increasing decomposer community complexity enhanced litter decomposition and allowing additional access of meso-and macro-fauna to litterbags mitigated the negative drought effect on the microbial-driven decomposition.Furthermore,both the increased diversity and altered trophic structure of nematode due to drought contributed to the mitigation effects via cascading interactions.Our results show that litter quality and soil decomposer community complexity co-drive the effect of drought on litter decomposition.This experimental finding provides a new insight into the mechanisms controlling forest floor C and nutrient cycling under future global change scenarios.展开更多
Electric vibrators find wide applications in reliability testing, waveform generation, and vibration simulation, making their noise characteristics a topic of significant interest. While Variational Mode Decomposition...Electric vibrators find wide applications in reliability testing, waveform generation, and vibration simulation, making their noise characteristics a topic of significant interest. While Variational Mode Decomposition (VMD) and Empirical Wavelet Transform (EWT) offer valuable support for studying signal components, they also present certain limitations. This article integrates the strengths of both methods and proposes an enhanced approach that integrates VMD into the frequency band division principle of EWT. Initially, the method decomposes the signal using VMD, determining the mode count based on residuals, and subsequently employs EWT decomposition based on this information. This addresses mode aliasing issues in the original method while capitalizing on VMD’s adaptability. Feasibility was confirmed through simulation signals and ultimately applied to noise signals from vibrators. Experimental results demonstrate that the improved method not only resolves EWT frequency band division challenges but also effectively decomposes signal components compared to the VMD method.展开更多
Sparse vector coding(SVC)is emerging as a potential technology for short packet communications.To further improve the block error rate(BLER)performance,a uniquely decomposable constellation group-based SVC(UDCG-SVC)is...Sparse vector coding(SVC)is emerging as a potential technology for short packet communications.To further improve the block error rate(BLER)performance,a uniquely decomposable constellation group-based SVC(UDCG-SVC)is proposed in this article.Additionally,in order to achieve an optimal BLER performance of UDCG-SVC,a problem to optimize the coding gain of UDCG-based superimposed constellation is formulated.Given the energy of rotation constellations in UDCG,this problem is solved by converting it into finding the maximized minimum Euclidean distance of the superimposed constellation.Simulation results demonstrate the validness of our derivation.We also find that the proposed UDCGSVC has better BLER performance compared to other SVC schemes,especially under the high order modulation scenarios.展开更多
The molecular dynamics method is used to investigate decomposition of methane hydrate at different temperatures,pressures and concentrations of inhibitor.By analyzing the parameters of system conformation,mean square ...The molecular dynamics method is used to investigate decomposition of methane hydrate at different temperatures,pressures and concentrations of inhibitor.By analyzing the parameters of system conformation,mean square displacement and radial distribution function,the decomposition of hydrate in the presence of alcohol inhibitors ethylene glycol and glycerol is explored.The results show that the hydroxyl groups in alcohol molecules can destroy the cage structure of hydrate,and form hydrogen bonds with nearby water molecules to effectively prevent the reformation of hydrate.Therefore,ethylene glycol and glycerol serve as inhibitors of methane hydrate,furthermore,in terms of inhibition effect,glycerol is better than ethylene glycol by comparing rate of hydrate decomposition.展开更多
A method was established for the analysis of omethoate and it’s concomitants and decomposed product in biological samples by GC-MS.This method is rapid,reliable and accurate.
In northern China, the soil-born diseases of wheat have been getting more and more serious under a new farming system that returns maize straw to the field. In order to investigate the allelopathy of the decomposed ma...In northern China, the soil-born diseases of wheat have been getting more and more serious under a new farming system that returns maize straw to the field. In order to investigate the allelopathy of the decomposed maize straw products on three soil-born diseases of wheat, culture dish and pot experiments were conducted and the compounds in the products were identified by gas chromatography-mass spectrometry (GC-MS). Culture dish experiments showed that the mycelial growth, sclerotia formation amount and total weight of Rhizoctonia cerealis were promoted at concentrations of 0.03, 0.06 and 0.12 g mL-1 and inhibited at concentration of 0.48 g mL-1 of the decomposed products. No significant effects were found of the product concentrations on average weight of the sclerotia. Mycelial growth of Gaeumannomyces graminis was promoted at almost all concentrations except the highest one. Mycelial growth and spore germination of Bipolaris sorokiniana were significantly inhibited by all concentrations of the decomposed products, with enhanced inhibition effects along with the increased concentrations. The length, number and dry weight of roots together with the root superoxide dismutase activity were promoted by the lowest concentration (0.03 g mL-1), with a synthetic effect index of 0.012, and inhibited by other concentrations. The ion leakage of roots was increased and the root peroxidase activity of roots was lowered by all the treatments. Pot experiments revealed that occurrence of the sharp eyespot was reduced by 0.03 and 0.06 g mL-1 of decomposed products after irrigation. However, the incidence rates and disease indexes were significantly increased by 0.12, 0.24 and 0.48 g mL-1 of decomposed products. The results indicated that incidence rates and disease indexes of the take-all were significantly promoted after being irrigated with the decomposed products, while occurrences of the common rot didn't change, significantly. GC-MS results showed that the compounds of the decomposed products included organic acids, esters, hydrocarbons, amides and aldehydes, with the proportions 25.26, 24.01, 17.22, 14.39 and 7.73%, respectively. Further analysis investigated that the allelochemicals identified in straw decomposed products contained p-hydroxybenzoic acid (9.21%), dibutyl phthalate (6.94%), 3-phenyl-2-acrylic (5.06%), 4-hydroxy-3,5-dimethoxybenzoic acid (2.26%), hexanoic acid (1.73%), 8-octadecenoic acid (1.06%), 3-(4-hydroxy-3-methoxy-phenyl)-2-propenoic acid (1.04%), 4-hydroxy-3-methoxy-benzoic acid (0.94%) and salicylic acid (0.94%).展开更多
As an oil-decomposable mixture of two bacteria strains(Bacillus sp. and Pseudomonas sp.), Y3 was isolated after 50 d domestication under the condition that oil was used as the limited carbon source. The decomposing ra...As an oil-decomposable mixture of two bacteria strains(Bacillus sp. and Pseudomonas sp.), Y3 was isolated after 50 d domestication under the condition that oil was used as the limited carbon source. The decomposing rate by Y3 was higher than that by each separate individual strain, indicating a synergistic effect of the two bacteria. Under the conditions that T=25—40℃,pH=6—8, HRT(Hydraulic retention time)=36 h and the oil concentration at 0.1%, Y3 yielded the highest decomposing rate of 95.7 %. Y3 was also applied in an organic waste treatment machine and a certain rate of activated bacteria was put into the stuffing. A series of tests including humidity, pH, temperature, C/N rate and oil percentage of the stuffing were carried out to check the efficacy of oil-decomposition. Results showed that the oil content of the stuffing with inoculums was only half of that of the control. Furthermore, the bacteria were also beneficial to maintain the stability of the machine operating. Therefore, the bacteria mixture as well as the machines in this study could be very useful for waste treatment.展开更多
Scissor-like element has a number of applications in deployable structures such as planar deployable structure (PDS) and ring deployable structure(RDS). However, the mobility analysis of the multi-loop deployable stru...Scissor-like element has a number of applications in deployable structures such as planar deployable structure (PDS) and ring deployable structure(RDS). However, the mobility analysis of the multi-loop deployable structures is made more difficulty by the traditional mobility formula, because the deployable structure is a very complex structure with multi-loop. Therefore, On the basis of screw theory, the calculation method of mobility of deployable structures of SLE is thoroughly discussed. In order to investigate the mobility, decomposing and composing structures(DCS) are developed, and the basic units are able to be obtained. On the basis of the deployable structures’ geometrical characteristics, there exists a closed-loop quadrilateral structure and some non-closed-loop quadrilateral structures in PDS. Also, a six legs parallel structure is present in RDS. The basic units’ mobility can be solved by both the methods of screw theory and topology constraint graphs. Then, composing the related basic units, the formula of planar deployable structures’ mobility can be built and solves the mobility of ring deployable structure. The analysis method solves the mobility analysis of the multi-loop deployable structures which is difficulty by the traditional method, and plays an important role in further research about the mobility of other complex deployable structures.展开更多
We collected the diseased blades of Larninaria japonica from Yantai Sea Farm from October to December 2002, and the alginic acid decomposing bacterium on the diseased blade was isolated and purified, and was identifie...We collected the diseased blades of Larninaria japonica from Yantai Sea Farm from October to December 2002, and the alginic acid decomposing bacterium on the diseased blade was isolated and purified, and was identified as A lteromonas espejiana. This bacterium was applied as the causative pathogen to infect the blades of L. japonica under laboratory conditions. The aim of the present study was to identify the effects of the bacterium on the growth of L. japonica, and to find the possibly effective mechanism. Results showed that: (1)The blades of L.japonica exhibited symptoms of lesion,bleaching and deteriortion when infected by the bacterium. and their growth and photosynthesis were dramatically suppressed. At the same time, the reactive oxygen species (ROS) generation enhanced obviously, and the relative membrane permeability increased significantly. The contents of malonaldehyde (MDA) and free fatty acid in the microsomol membrane greatly elevated, but the phospholipid content decreased. Result suggested an obvious peroxidation and deesterrification in the blades of L. japonica when infected by the bacterium. (2) The simultaneous assay on the antioxidant enzyme activities demonstrated that superoxide dismutase (SOD) and catalase (CAT) increased greatly when infected by the bacterium, but glutathione peroxidase (Gpx) and ascorbate peroxidase (APX) did not exhibit active responses to the bacterium throughout the experiment. (3) The histomorphological observations gave a distinctive evidence of the severity of the lesions as well as the relative abundance in the bacterial population on the blades after infection. The bacterium firstly invaded into the endodermis of L. japonica and gathered around there, and then resulted in the membrane damage, cells corruption and ultimately, the death of L. japonica.展开更多
Biosurfactant,produced by Pseudomonas aeruginosa BSZ-07,was added to the dee straw decomposing process to enhance the production of reducing sugars.Observed by Fourier Transform InfraRed(FT-IR)and Nuclear Magnetic Res...Biosurfactant,produced by Pseudomonas aeruginosa BSZ-07,was added to the dee straw decomposing process to enhance the production of reducing sugars.Observed by Fourier Transform InfraRed(FT-IR)and Nuclear Magnetic Resonance(NMR)analysis, the purified biosurfactant was considered as a mixture of RL1 and RL2,which are two different types of rhamnolipids.Two different adding methods,adding the purified rhamnolipid and the on-site production of it were compared.The results showed that 0.5 g/L was the optimum co...展开更多
In order to make full use of salt lake magnesium resources and improve the strength of the thermal decomposed magnesium oxychloride cement (TDMOC), the effects of citric acid on the hydration process and mechanical ...In order to make full use of salt lake magnesium resources and improve the strength of the thermal decomposed magnesium oxychloride cement (TDMOC), the effects of citric acid on the hydration process and mechanical properties of TDMOC was studied. The hydration heat release at initial 24 h and strengths at 3, 7, and 28 days of TDMOC specimens were conducted. The hydration products and paste microstructure were analyzed by XRD, FT-IR and SEM, respectively. The results showed that citric acid can not only reduce the 24 h hydration heat release and delay the occurring time of second peak of TDMOC, but also produce more 5Mg(OH)z.MgC12.SH20 and less Mg(OH)2 in hydration process of TDMOC. More perfect and slender crystals were observed in the microstructure of the TDMOC pastes with citric acid. The results demonstrated that citric acid as an additive of TDMOC can decrease the hydration heat release and increase the compressive strength and flexural strength of TDMOC. The possible mechanism for the strength enhancement was discussed.展开更多
The low-temperature performance of Li-ion batteries(LIBs) has important impacts on their commercial applications. Besides the metallic lithium deposition, which is regarded as one of the main failure mechanisms of the...The low-temperature performance of Li-ion batteries(LIBs) has important impacts on their commercial applications. Besides the metallic lithium deposition, which is regarded as one of the main failure mechanisms of the LIBs at low temperatures, the synergistic effects originating from the cathode, anode, electrolyte, and separators to the batteries are still not clear. Here, the 21700-type cylindrical batteries were evaluated at a wide range of temperatures to investigate the failure mechanism of batteries. Voltage relaxation, and the post-mortem analysis combined with the electrochemical tests, unravel that the capacity degradation of batteries at low temperature is related to the lithium plating at graphite anodes,the formation of unsatisfied solid deposited/decomposed electrolyte mixture phase on the anode, the precipitation of solvent in the electrolytes and the block of separator pores, and the uneven dissolved transition metal-ions from the cathode. We hope this finding may open up a new avenue to alleviate the capacity degradation of advanced LIBs at low temperatures and shed light on the development of outstanding low-temperature LIBs via simultaneous optimization of all the components including electrodes, electrolytes and separators.展开更多
During the period of May to October in1999,systematical studies were giv en to the rate of decomposition of Calamagrostis angustifolia litter,the phosphorus content and weight in decomposed residua of litte r,and phos...During the period of May to October in1999,systematical studies were giv en to the rate of decomposition of Calamagrostis angustifolia litter,the phosphorus content and weight in decomposed residua of litte r,and phosphorus content in the corresponding soil in the Sanjiang Plain.At the same time,the simulation models were listed in the paper.The results showed that the rate of we ight lost of decomposition of Calamagrostis angustifolia litter is 29.80%and the maximum of daily rate of weight lost i s 0.25%,which appeared in July.The c hange trend of phosphorus content an d weight in the decomposed residua of l itter is to reduce with the decomposing process,when it comes to the day of157,the decrement amount of the both were respectively 57.69mg /kg and 1.6199mg,which were 72.80%and 76.30%of its previous amount.In addition,th ere is a polynomial minus correlatio nship of phosphorus content between the variation in corresponding soil and the decomp osed residua of litter at the corresp onding period.The study will be help ful to further understand the process and mechanis m of biochemical cycling of nutrient elements in wetland ecosystems,in a ddition,it will also be helpful to the restoration and rebuilding of retrogressive wetlands and reasonable development and utilization of wetlands in the Sanjiang Plain.展开更多
A method of woven fabric defect detection using the wavelet transform adaptive to the fabric has been developed. With reference to the orthogonality constrains of Daubechies wavelet, by taking the mmimization of the e...A method of woven fabric defect detection using the wavelet transform adaptive to the fabric has been developed. With reference to the orthogonality constrains of Daubechies wavelet, by taking the mmimization of the energy or the gray level of the pixels in the output sub-images as the additional conditions and using the random algorithm method, two sets of wavelet filters adapted to the fabric texture were formed. The original images of normal fabric texture and the fabric texture with defects were decomposed into horizontal and vertical sub- images by using these filters and the feature indices of these sub-images were also extracted. By comparing the feature indices of the normal texture with that of the defective texture, the fabric defects can be successfully detected and located.展开更多
Using Bressan-Colombo results, concerning the existence of continuous selections of lower semicontinuous multifunctions with decomposable values, we prove a continuous version of Filippov's theorem for a fractional i...Using Bressan-Colombo results, concerning the existence of continuous selections of lower semicontinuous multifunctions with decomposable values, we prove a continuous version of Filippov's theorem for a fractional integro-differential inclusion involving Caputo's fractional derivative. This result allows us to obtain a continuous selection of the solution set of the problem considered.展开更多
A statistical downscaling approach was developed to improve seasonal-to-interannual prediction of summer rainfall over North China by considering the effect of decadal variability based on observational datasets and d...A statistical downscaling approach was developed to improve seasonal-to-interannual prediction of summer rainfall over North China by considering the effect of decadal variability based on observational datasets and dynamical model outputs.Both predictands and predictors were first decomposed into interannual and decadal components.Two predictive equations were then built separately for the two distinct timescales by using multivariate linear regressions based on independent sample validation.For the interannual timescale,850-hPa meridional wind and 500-hPa geopotential heights from multiple dynamical models' hindcasts and SSTs from observational datasets were used to construct predictors.For the decadal timescale,two well-known basin-scale SST decadal oscillation (the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation) indices were used as predictors.Then,the downscaled predictands were combined to represent the predicted/hindcasted total rainfall.The prediction was compared with the models' raw hindcasts and those from a similar approach but without timescale decomposition.In comparison to hindcasts from individual models or their multi-model ensemble mean,the skill of the present scheme was found to be significantly higher,with anomaly correlation coefficients increasing from nearly neutral to over 0.4 and with RMSE decreasing by up to 0.6 mm d-1.The improvements were also seen in the station-based temporal correlation of the predictions with observed rainfall,with the coefficients ranging from-0.1 to 0.87,obviously higher than the models' raw hindcasted rainfall results.Thus,the present approach exhibits a great advantage and may be appropriate for use in operational predictions.展开更多
This paper introduces two new types of precise integration methods based on Chebyshev polynomial of the first kind for dynamic response analysis of structures, namely the integral formula method (IFM) and the homoge...This paper introduces two new types of precise integration methods based on Chebyshev polynomial of the first kind for dynamic response analysis of structures, namely the integral formula method (IFM) and the homogenized initial system method (HISM). In both methods, nonlinear variable loadings within time intervals are simulated using Chebyshev polynomials of the first kind before a direct integration is performed. Developed on the basis of the integral formula, the recurrence relationship of the integral computation suggested in this paper is combined with the Crout decomposed method to solve linear algebraic equations. In this way, the IFM based on Chebyshev polynomial of the first kind is constructed. Transforming the non-homogenous initial system to the homogeneous dynamic system, and developing a special scheme without dimensional expansion, the HISM based on Chebyshev polynomial of the first kind is able to avoid the matrix inversion operation. The accuracy of the time integration schemes is examined and compared with other commonly used schemes, and it is shown that a greater accuracy as well as less time consuming can be achieved. Two numerical examples are presented to demonstrate the applicability of these new methods.展开更多
A timescale decomposed threshold regression (TSDTR) downscaling approach to forecasting South China early summer rainfall (SCESR) is described by using long-term observed station rainfall data and NOAA ERSST data....A timescale decomposed threshold regression (TSDTR) downscaling approach to forecasting South China early summer rainfall (SCESR) is described by using long-term observed station rainfall data and NOAA ERSST data. It makes use of two distinct regression downscaling models corresponding to the interannual and interdecadal rainfall variability of SCESR. The two models are developed based on the partial least squares (PLS) regression technique, linking SCESR to SST modes in preceding months on both interannual and interdecadal timescales. Specifically, using the datasets in the calibration period 1915-84, the variability of SCESR and SST are decomposed into interannual and interdecadal components. On the interannual timescale, a threshold PLS regression model is fitted to interannual components of SCESR and March SST patterns by taking account of the modulation of negative and positive phases of the Pacific Decadal Oscillation (PDO). On the interdecadal timescale, a standard PLS regression model is fitted to the relationship between SCESR and preceding November SST patterns. The total rainfall prediction is obtained by the sum of the outputs from both the interannual and interdecadal models. Results show that the TSDTR downscaling approach achieves reasonable skill in predicting the observed rainfall in the validation period 1985-2006, compared to other simpler approaches. This study suggests that the TSDTR approach, considering different interannual SCESR-SST relationships under the modulation of PDO phases, as well as the interdecadal variability of SCESR associated with SST patterns, may provide a new perspective to improve climate predictions.展开更多
The method of empirical orthogonal modes has been widely used since the 1970’s in physical oceanography to study and rebuild vertical structures of ocean dynamic factors. Because of the dominance of the low modes, th...The method of empirical orthogonal modes has been widely used since the 1970’s in physical oceanography to study and rebuild vertical structures of ocean dynamic factors. Because of the dominance of the low modes, the dynamic profile data can be largely reduced.Up to now, all expressions of empirical orthogonal modes are numerical. In this study, an analytic expression for empirical orthogonal ocean modes is constructed for convenient use whereby any numerical expressions can be repeated.The features of the normal modes decomposed from the buoyance frequency profiles obtained in October of 1986,1987 and 1988 by the R/V Science 1 in the western Pacific are quantitatively examined in this study.展开更多
基金jointly funded by the National Natural Science Foundation of China(No.31930078)the National Key R&D Program of China(No.2021YFD2200405)+3 种基金Science and Technology Cooperation Projects between governments of China and the European Union(No.2023YFE0105100)the Fundamental Research Funds for ICBR(No.1632021023)Sanya Research Base of ICBR(No.1630032023002)the Scientific and Technological Innovation Team for Qinghai-Tibetan Plateau Research in Southwest Minzu University(No.2024CXTD10)。
文摘Litter decomposition is key to ecosystem carbon(C)and nutrient cycling,but this process is anticipated to weaken due to projected more extensive and prolonged drought.Yet how litter quality and decomposer community complexity regulate decomposition in response to drought is less understood.Here,in a five-year manipulative drought experiment in a Masson pine forest,leaf litter from four subtropical tree species(Quercus griffthii Hook.f.&Thomson ex Miq.,Acacia mangium Willd.,Pinus massoniana Lamb.,Castanopsis hystrix Miq.)representing different qualities was decomposed for 350 d in litterbags of three different mesh sizes(i.e.,0.05,1,and 5 mm),respectively,under natural conditions and a 50%throughfall rain exclusion treatment.Litterbags of increasing mesh sizes discriminate decomposer communities(i.e.,microorganisms,microorganisms and mesofauna,microorganisms and meso-and macrofauna)that access the litter and represent an increasing complexity.The amount of litter C and nitrogen(N)loss,and changes in their ratio(C/N_(loss)),as well as small and medium-sized decomposers including microorganisms,nematodes,and arthropods,were investigated.We found that drought did not affect C and N loss but decreased C/N_(loss)(i.e.,decomposer N use efficiency)of leaf litter irrespective of litter quality and decomposer complexity.However,changes in the C/N_(loss)and the drought effect on C loss were both dependent on litter quality,while drought and decomposer complexity interactively affected litter C and N loss.Increasing decomposer community complexity enhanced litter decomposition and allowing additional access of meso-and macro-fauna to litterbags mitigated the negative drought effect on the microbial-driven decomposition.Furthermore,both the increased diversity and altered trophic structure of nematode due to drought contributed to the mitigation effects via cascading interactions.Our results show that litter quality and soil decomposer community complexity co-drive the effect of drought on litter decomposition.This experimental finding provides a new insight into the mechanisms controlling forest floor C and nutrient cycling under future global change scenarios.
文摘Electric vibrators find wide applications in reliability testing, waveform generation, and vibration simulation, making their noise characteristics a topic of significant interest. While Variational Mode Decomposition (VMD) and Empirical Wavelet Transform (EWT) offer valuable support for studying signal components, they also present certain limitations. This article integrates the strengths of both methods and proposes an enhanced approach that integrates VMD into the frequency band division principle of EWT. Initially, the method decomposes the signal using VMD, determining the mode count based on residuals, and subsequently employs EWT decomposition based on this information. This addresses mode aliasing issues in the original method while capitalizing on VMD’s adaptability. Feasibility was confirmed through simulation signals and ultimately applied to noise signals from vibrators. Experimental results demonstrate that the improved method not only resolves EWT frequency band division challenges but also effectively decomposes signal components compared to the VMD method.
基金supported by the National Science Fundation of China(NSFC)under grant 62001423the Henan Provincial Key Research,Development and Promotion Project under grant 212102210175the Henan Provincial Key Scientific Research Project for College and University under grant 21A510011.
文摘Sparse vector coding(SVC)is emerging as a potential technology for short packet communications.To further improve the block error rate(BLER)performance,a uniquely decomposable constellation group-based SVC(UDCG-SVC)is proposed in this article.Additionally,in order to achieve an optimal BLER performance of UDCG-SVC,a problem to optimize the coding gain of UDCG-based superimposed constellation is formulated.Given the energy of rotation constellations in UDCG,this problem is solved by converting it into finding the maximized minimum Euclidean distance of the superimposed constellation.Simulation results demonstrate the validness of our derivation.We also find that the proposed UDCGSVC has better BLER performance compared to other SVC schemes,especially under the high order modulation scenarios.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51876032)the Natural Science Foundation of Heilongjiang Province of China(Grant No.ZD2019E002).
文摘The molecular dynamics method is used to investigate decomposition of methane hydrate at different temperatures,pressures and concentrations of inhibitor.By analyzing the parameters of system conformation,mean square displacement and radial distribution function,the decomposition of hydrate in the presence of alcohol inhibitors ethylene glycol and glycerol is explored.The results show that the hydroxyl groups in alcohol molecules can destroy the cage structure of hydrate,and form hydrogen bonds with nearby water molecules to effectively prevent the reformation of hydrate.Therefore,ethylene glycol and glycerol serve as inhibitors of methane hydrate,furthermore,in terms of inhibition effect,glycerol is better than ethylene glycol by comparing rate of hydrate decomposition.
文摘A method was established for the analysis of omethoate and it’s concomitants and decomposed product in biological samples by GC-MS.This method is rapid,reliable and accurate.
基金financially supported by the Key Technologies R&D Program of China during the 12th FiveYear Plan period (2011BAD16B08, 2012BAD04B06 and 2013BAD07B05)
文摘In northern China, the soil-born diseases of wheat have been getting more and more serious under a new farming system that returns maize straw to the field. In order to investigate the allelopathy of the decomposed maize straw products on three soil-born diseases of wheat, culture dish and pot experiments were conducted and the compounds in the products were identified by gas chromatography-mass spectrometry (GC-MS). Culture dish experiments showed that the mycelial growth, sclerotia formation amount and total weight of Rhizoctonia cerealis were promoted at concentrations of 0.03, 0.06 and 0.12 g mL-1 and inhibited at concentration of 0.48 g mL-1 of the decomposed products. No significant effects were found of the product concentrations on average weight of the sclerotia. Mycelial growth of Gaeumannomyces graminis was promoted at almost all concentrations except the highest one. Mycelial growth and spore germination of Bipolaris sorokiniana were significantly inhibited by all concentrations of the decomposed products, with enhanced inhibition effects along with the increased concentrations. The length, number and dry weight of roots together with the root superoxide dismutase activity were promoted by the lowest concentration (0.03 g mL-1), with a synthetic effect index of 0.012, and inhibited by other concentrations. The ion leakage of roots was increased and the root peroxidase activity of roots was lowered by all the treatments. Pot experiments revealed that occurrence of the sharp eyespot was reduced by 0.03 and 0.06 g mL-1 of decomposed products after irrigation. However, the incidence rates and disease indexes were significantly increased by 0.12, 0.24 and 0.48 g mL-1 of decomposed products. The results indicated that incidence rates and disease indexes of the take-all were significantly promoted after being irrigated with the decomposed products, while occurrences of the common rot didn't change, significantly. GC-MS results showed that the compounds of the decomposed products included organic acids, esters, hydrocarbons, amides and aldehydes, with the proportions 25.26, 24.01, 17.22, 14.39 and 7.73%, respectively. Further analysis investigated that the allelochemicals identified in straw decomposed products contained p-hydroxybenzoic acid (9.21%), dibutyl phthalate (6.94%), 3-phenyl-2-acrylic (5.06%), 4-hydroxy-3,5-dimethoxybenzoic acid (2.26%), hexanoic acid (1.73%), 8-octadecenoic acid (1.06%), 3-(4-hydroxy-3-methoxy-phenyl)-2-propenoic acid (1.04%), 4-hydroxy-3-methoxy-benzoic acid (0.94%) and salicylic acid (0.94%).
文摘As an oil-decomposable mixture of two bacteria strains(Bacillus sp. and Pseudomonas sp.), Y3 was isolated after 50 d domestication under the condition that oil was used as the limited carbon source. The decomposing rate by Y3 was higher than that by each separate individual strain, indicating a synergistic effect of the two bacteria. Under the conditions that T=25—40℃,pH=6—8, HRT(Hydraulic retention time)=36 h and the oil concentration at 0.1%, Y3 yielded the highest decomposing rate of 95.7 %. Y3 was also applied in an organic waste treatment machine and a certain rate of activated bacteria was put into the stuffing. A series of tests including humidity, pH, temperature, C/N rate and oil percentage of the stuffing were carried out to check the efficacy of oil-decomposition. Results showed that the oil content of the stuffing with inoculums was only half of that of the control. Furthermore, the bacteria were also beneficial to maintain the stability of the machine operating. Therefore, the bacteria mixture as well as the machines in this study could be very useful for waste treatment.
基金supported by National Natural Science Foundation of China(Grant No. 50875210)
文摘Scissor-like element has a number of applications in deployable structures such as planar deployable structure (PDS) and ring deployable structure(RDS). However, the mobility analysis of the multi-loop deployable structures is made more difficulty by the traditional mobility formula, because the deployable structure is a very complex structure with multi-loop. Therefore, On the basis of screw theory, the calculation method of mobility of deployable structures of SLE is thoroughly discussed. In order to investigate the mobility, decomposing and composing structures(DCS) are developed, and the basic units are able to be obtained. On the basis of the deployable structures’ geometrical characteristics, there exists a closed-loop quadrilateral structure and some non-closed-loop quadrilateral structures in PDS. Also, a six legs parallel structure is present in RDS. The basic units’ mobility can be solved by both the methods of screw theory and topology constraint graphs. Then, composing the related basic units, the formula of planar deployable structures’ mobility can be built and solves the mobility of ring deployable structure. The analysis method solves the mobility analysis of the multi-loop deployable structures which is difficulty by the traditional method, and plays an important role in further research about the mobility of other complex deployable structures.
基金The Hi-Tech Research and Development Program (863) of China (Youth Program) (No. 2004AA639770) and the Chinese NationalBasic Research Priorities Program (No. G1999012004)
文摘We collected the diseased blades of Larninaria japonica from Yantai Sea Farm from October to December 2002, and the alginic acid decomposing bacterium on the diseased blade was isolated and purified, and was identified as A lteromonas espejiana. This bacterium was applied as the causative pathogen to infect the blades of L. japonica under laboratory conditions. The aim of the present study was to identify the effects of the bacterium on the growth of L. japonica, and to find the possibly effective mechanism. Results showed that: (1)The blades of L.japonica exhibited symptoms of lesion,bleaching and deteriortion when infected by the bacterium. and their growth and photosynthesis were dramatically suppressed. At the same time, the reactive oxygen species (ROS) generation enhanced obviously, and the relative membrane permeability increased significantly. The contents of malonaldehyde (MDA) and free fatty acid in the microsomol membrane greatly elevated, but the phospholipid content decreased. Result suggested an obvious peroxidation and deesterrification in the blades of L. japonica when infected by the bacterium. (2) The simultaneous assay on the antioxidant enzyme activities demonstrated that superoxide dismutase (SOD) and catalase (CAT) increased greatly when infected by the bacterium, but glutathione peroxidase (Gpx) and ascorbate peroxidase (APX) did not exhibit active responses to the bacterium throughout the experiment. (3) The histomorphological observations gave a distinctive evidence of the severity of the lesions as well as the relative abundance in the bacterial population on the blades after infection. The bacterium firstly invaded into the endodermis of L. japonica and gathered around there, and then resulted in the membrane damage, cells corruption and ultimately, the death of L. japonica.
文摘Biosurfactant,produced by Pseudomonas aeruginosa BSZ-07,was added to the dee straw decomposing process to enhance the production of reducing sugars.Observed by Fourier Transform InfraRed(FT-IR)and Nuclear Magnetic Resonance(NMR)analysis, the purified biosurfactant was considered as a mixture of RL1 and RL2,which are two different types of rhamnolipids.Two different adding methods,adding the purified rhamnolipid and the on-site production of it were compared.The results showed that 0.5 g/L was the optimum co...
基金Funded by One-Hundred Talent Project of CAS(No.B0210)the Qinghai Province Science and Technology Tackling Key Project(No.2008-G-158)
文摘In order to make full use of salt lake magnesium resources and improve the strength of the thermal decomposed magnesium oxychloride cement (TDMOC), the effects of citric acid on the hydration process and mechanical properties of TDMOC was studied. The hydration heat release at initial 24 h and strengths at 3, 7, and 28 days of TDMOC specimens were conducted. The hydration products and paste microstructure were analyzed by XRD, FT-IR and SEM, respectively. The results showed that citric acid can not only reduce the 24 h hydration heat release and delay the occurring time of second peak of TDMOC, but also produce more 5Mg(OH)z.MgC12.SH20 and less Mg(OH)2 in hydration process of TDMOC. More perfect and slender crystals were observed in the microstructure of the TDMOC pastes with citric acid. The results demonstrated that citric acid as an additive of TDMOC can decrease the hydration heat release and increase the compressive strength and flexural strength of TDMOC. The possible mechanism for the strength enhancement was discussed.
基金supported by the National Natural Science Foundation of China (U1664255, 21875022, 51802020, U1564206)the National Key R&D Program of China (2016YFB0100301)+2 种基金the Science and Technology Innovation Foundation of Beijing Institute of Technology Chongqing Innovation Center (2020CX5100006)the Young Elite Scientists Sponsorship Program by CAST (2018QNRC001)support from Beijing Institute of Technology Research Fund Program for Young Scholars。
文摘The low-temperature performance of Li-ion batteries(LIBs) has important impacts on their commercial applications. Besides the metallic lithium deposition, which is regarded as one of the main failure mechanisms of the LIBs at low temperatures, the synergistic effects originating from the cathode, anode, electrolyte, and separators to the batteries are still not clear. Here, the 21700-type cylindrical batteries were evaluated at a wide range of temperatures to investigate the failure mechanism of batteries. Voltage relaxation, and the post-mortem analysis combined with the electrochemical tests, unravel that the capacity degradation of batteries at low temperature is related to the lithium plating at graphite anodes,the formation of unsatisfied solid deposited/decomposed electrolyte mixture phase on the anode, the precipitation of solvent in the electrolytes and the block of separator pores, and the uneven dissolved transition metal-ions from the cathode. We hope this finding may open up a new avenue to alleviate the capacity degradation of advanced LIBs at low temperatures and shed light on the development of outstanding low-temperature LIBs via simultaneous optimization of all the components including electrodes, electrolytes and separators.
文摘During the period of May to October in1999,systematical studies were giv en to the rate of decomposition of Calamagrostis angustifolia litter,the phosphorus content and weight in decomposed residua of litte r,and phosphorus content in the corresponding soil in the Sanjiang Plain.At the same time,the simulation models were listed in the paper.The results showed that the rate of we ight lost of decomposition of Calamagrostis angustifolia litter is 29.80%and the maximum of daily rate of weight lost i s 0.25%,which appeared in July.The c hange trend of phosphorus content an d weight in the decomposed residua of l itter is to reduce with the decomposing process,when it comes to the day of157,the decrement amount of the both were respectively 57.69mg /kg and 1.6199mg,which were 72.80%and 76.30%of its previous amount.In addition,th ere is a polynomial minus correlatio nship of phosphorus content between the variation in corresponding soil and the decomp osed residua of litter at the corresp onding period.The study will be help ful to further understand the process and mechanis m of biochemical cycling of nutrient elements in wetland ecosystems,in a ddition,it will also be helpful to the restoration and rebuilding of retrogressive wetlands and reasonable development and utilization of wetlands in the Sanjiang Plain.
基金This research was supported by the Research Fund for the Doctoral Program of Higher Education, No.99025508
文摘A method of woven fabric defect detection using the wavelet transform adaptive to the fabric has been developed. With reference to the orthogonality constrains of Daubechies wavelet, by taking the mmimization of the energy or the gray level of the pixels in the output sub-images as the additional conditions and using the random algorithm method, two sets of wavelet filters adapted to the fabric texture were formed. The original images of normal fabric texture and the fabric texture with defects were decomposed into horizontal and vertical sub- images by using these filters and the feature indices of these sub-images were also extracted. By comparing the feature indices of the normal texture with that of the defective texture, the fabric defects can be successfully detected and located.
基金supported by CNCS grant PN-II-ID-PCE-2011-3-0198
文摘Using Bressan-Colombo results, concerning the existence of continuous selections of lower semicontinuous multifunctions with decomposable values, we prove a continuous version of Filippov's theorem for a fractional integro-differential inclusion involving Caputo's fractional derivative. This result allows us to obtain a continuous selection of the solution set of the problem considered.
基金supported by the Special Program in the Public Interest of the China Meteorological Administration (Grant No. GYHY201006022)the Strategic Special Projects of the Chinese Academy of Sciences (Grant No. XDA05090000)
文摘A statistical downscaling approach was developed to improve seasonal-to-interannual prediction of summer rainfall over North China by considering the effect of decadal variability based on observational datasets and dynamical model outputs.Both predictands and predictors were first decomposed into interannual and decadal components.Two predictive equations were then built separately for the two distinct timescales by using multivariate linear regressions based on independent sample validation.For the interannual timescale,850-hPa meridional wind and 500-hPa geopotential heights from multiple dynamical models' hindcasts and SSTs from observational datasets were used to construct predictors.For the decadal timescale,two well-known basin-scale SST decadal oscillation (the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation) indices were used as predictors.Then,the downscaled predictands were combined to represent the predicted/hindcasted total rainfall.The prediction was compared with the models' raw hindcasts and those from a similar approach but without timescale decomposition.In comparison to hindcasts from individual models or their multi-model ensemble mean,the skill of the present scheme was found to be significantly higher,with anomaly correlation coefficients increasing from nearly neutral to over 0.4 and with RMSE decreasing by up to 0.6 mm d-1.The improvements were also seen in the station-based temporal correlation of the predictions with observed rainfall,with the coefficients ranging from-0.1 to 0.87,obviously higher than the models' raw hindcasted rainfall results.Thus,the present approach exhibits a great advantage and may be appropriate for use in operational predictions.
基金Hunan Provincial Natural Science Foundation Under Grant No.02JJY2085
文摘This paper introduces two new types of precise integration methods based on Chebyshev polynomial of the first kind for dynamic response analysis of structures, namely the integral formula method (IFM) and the homogenized initial system method (HISM). In both methods, nonlinear variable loadings within time intervals are simulated using Chebyshev polynomials of the first kind before a direct integration is performed. Developed on the basis of the integral formula, the recurrence relationship of the integral computation suggested in this paper is combined with the Crout decomposed method to solve linear algebraic equations. In this way, the IFM based on Chebyshev polynomial of the first kind is constructed. Transforming the non-homogenous initial system to the homogeneous dynamic system, and developing a special scheme without dimensional expansion, the HISM based on Chebyshev polynomial of the first kind is able to avoid the matrix inversion operation. The accuracy of the time integration schemes is examined and compared with other commonly used schemes, and it is shown that a greater accuracy as well as less time consuming can be achieved. Two numerical examples are presented to demonstrate the applicability of these new methods.
基金sponsored by the National Basic Research Program of China (Grant No. 2012CB955202)the China Scholarship Council under the Joint-PhD program for conducting research at CSIROsupported by the Indian Ocean Climate Initiative
文摘A timescale decomposed threshold regression (TSDTR) downscaling approach to forecasting South China early summer rainfall (SCESR) is described by using long-term observed station rainfall data and NOAA ERSST data. It makes use of two distinct regression downscaling models corresponding to the interannual and interdecadal rainfall variability of SCESR. The two models are developed based on the partial least squares (PLS) regression technique, linking SCESR to SST modes in preceding months on both interannual and interdecadal timescales. Specifically, using the datasets in the calibration period 1915-84, the variability of SCESR and SST are decomposed into interannual and interdecadal components. On the interannual timescale, a threshold PLS regression model is fitted to interannual components of SCESR and March SST patterns by taking account of the modulation of negative and positive phases of the Pacific Decadal Oscillation (PDO). On the interdecadal timescale, a standard PLS regression model is fitted to the relationship between SCESR and preceding November SST patterns. The total rainfall prediction is obtained by the sum of the outputs from both the interannual and interdecadal models. Results show that the TSDTR downscaling approach achieves reasonable skill in predicting the observed rainfall in the validation period 1985-2006, compared to other simpler approaches. This study suggests that the TSDTR approach, considering different interannual SCESR-SST relationships under the modulation of PDO phases, as well as the interdecadal variability of SCESR associated with SST patterns, may provide a new perspective to improve climate predictions.
文摘The method of empirical orthogonal modes has been widely used since the 1970’s in physical oceanography to study and rebuild vertical structures of ocean dynamic factors. Because of the dominance of the low modes, the dynamic profile data can be largely reduced.Up to now, all expressions of empirical orthogonal modes are numerical. In this study, an analytic expression for empirical orthogonal ocean modes is constructed for convenient use whereby any numerical expressions can be repeated.The features of the normal modes decomposed from the buoyance frequency profiles obtained in October of 1986,1987 and 1988 by the R/V Science 1 in the western Pacific are quantitatively examined in this study.