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IntroductionPu-erh tea is a geographical indication product of China. The characteristic flavor compounds produced during the fermentation of ripened Pu-erh tea have an important impact on its quality.MethodsHeadspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) and odor activity value (OAV) is used for flavor analysis.ResultsA total of 135 volatile compounds were annotated, of which the highest content was alcohols (54.26%), followed by esters (16.73%), and methoxybenzenes (12.69%). Alcohols in ripened Pu-erh tea mainly contribute flower and fruit sweet flavors, while methoxybenzenes mainly contribute musty and stale flavors. The ripened Pu-erh tea fermented by Saccharomyces: Rhizopus: Aspergillus niger mixed in the ratio of 1:1:1 presented the remarkable flavor characteristics of flower and fruit sweet flavor, and having better coordination with musty and stale flavor.DiscussionThis study demonstrated the content changes of ripened Pu-erh tea’s flavor compounds in the fermentation process, and revealed the optimal fermentation time. This will be helpful to further understand the formation mechanism of the characteristic flavor of ripened Pu-erh tea and guide the optimization of the fermentation process of ripened Pu-erh tea.

To study the fire spread law in high-speed railway stations and suggest a reasonable evacuation plan, we first establish a physical model based on a high-speed railway station in the Shandong building using Pyrosim software. We then simulate and analyze the variation rules for the smoke temperature, CO volume fraction, and visibility in the commercial mezzanine and waiting-hall space for a left-side fire and identify the most critical factors affecting personnel evacuation. Anylogic software, which considers the crowd social forces as well as the effect of visibility on personnel speed in areas where the fire is dynamically spreading, is used to compare and analyze the free-evacuation scheme and different guided evacuation schemes in terms of the required safety evacuation time. The optimal fire emergency evacuation scheme is then proposed. The results show that the smoke from a fire on the left commercial mezzanine will seriously threaten the upper stair entrance of the commercial mezzanine. Notably, visibility is the most critical factor affecting personnel evacuation. Under the free evacuation scheme, the utilization of evacuation exits is not balanced, and unsurprisingly, personnel congestion at the station entrance occurs. This affects evacuation efficiency. Accordingly, changing the evacuation personnel path and evacuation exit based on the shortest path under equal-area zoning evacuation can effectively reduce the personnel evacuation time.

Polypropylene (PP) membrane has been widely used in water purification and other fields owing to special pore structure, excellent mechanical properties and resistance to acids, alkalis and organic solvents. However, it is difficult for PP to introduce the hydrophilic chemical compositions for oil–water separation. Herein, superhydrophilic and underwater superoleophobic PP membranes were prepared by ALD for efficient gravity-driven oil–water separation. Owing to synergistic effect, oil contact angle of TiO2 coated PP membrane under water can reach above 150°. Hence, TiO2 coated PP membrane has great oil-repelling performance. Because of the superwetting property, TiO2 coated PP membrane can easily separate oil–water mixture and have high separation efficiency (more than 95%). The outstanding recyclability and mechanical stability of TiO2 coated PP membrane suggest the promising potential application in practical oil–water separation.

Peripartal cows often experience negative energy balance, and are therefore prone to suffering from metabolic diseases such as hyperketonemia, which causes financial losses in dairy farms. This study aimed to investigate the effect of green tea polyphenol (GTP) supplementation during the periparturient period on production performance, oxidative stress and immunometabolism in dairy cows with hyperketonemia. One hundred Holstein cows were assigned to GTP (0.2 g/kg DM; n = 50) or control (without GTP; n = 50) group based on body weight, previous milk yield, and parity on d 15 before expected parturition. Subsequently, 10 cows with hyperketonemia were selected from each group, according to blood β-hydroxybutyric acid (BHBA) concentration between 1.2 and 2.9 mmol/L from d 2 to 3 postpartum. All cows were fed a close-up diet and a lactation diet with or without GTP supply from d 15 prepartum until d 30 postpartum. Milk and blood samples were obtained from 20 cows selected with hyperketonemia on d 10, 20, and 30 postpartum. Compared with control cows, greater milk yield and lower somatic cell count were observed in GTP cows. The GTP group had lower concentrations of BHBA, free fatty acids, cholesterol, triglyceride, reactive oxygen species, malondialdehyde, and hydrogen peroxide, greater concentrations of glucose, lower activities of aspartate aminotransferase, alanine aminotransferase, and glutamyl transpeptidase, alongside greater activities of superoxide dismutase, glutathione peroxidase, and total antioxidant capacity. Additionally, GTP supplementation up-regulated concentrations of interleukin-6 and interleukin-10, but down-regulated concentrations of tumor necrosis factor-α, interleukin-1β, interleukin-2, interleukin-8, and interferon-γ in plasma. Greater concentrations of plasma immunoglobulin G were also detected in the GTP group. Overall, the data suggested that GTP supplementation from 15 d prepartum to 30 d postpartum improved the milk yield and health status in cows with hyperketonemia during early lactation.

Additional file 1: Figure S1. Size-selection NIPS can remarkably decrease the false negative of standard NIPS in the case 5 and 6. (A–C) SNP array, cfDNA testing without enrichment and cfDNA testing with enrichment results in case 5. (D–F) SNP array, cfDNA testing without enrichment and cfDNA testing with enrichment results in case 6.

Lyophilized wool nanoparticle powders (L-WNPP) derived from wool fibers, were extracted through the neutralization method. Here, we propose the mechanism of wool nanoparticle (WNP) formation in an aqueous solution. The effects of pH, alkali concentration, and alkali treatment time on the size and morphology of WNP were investigated. Results confirmed that WNP were well dispersed and stable in the aqueous solution and globular particles were identified with an average size of 50 nm by using 3% sodium hydroxide (NaOH) after a 4-h treatment through dynamic light scattering (DLS), zeta potential, scanning electron microscopy (SEM), and transmission electron microscope (TEM) analyses. Furthermore, fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses showed that the L-WNPP maintained the chemical structure of wool protein. X-ray photoelectron spectroscopy (XPS) analysis demonstrated that higher concentrations alkaline would destroy most amide bonds of molecule chains. Moreover, L-WNPP were further used to prepare transparent protein nanoparticle films. Our results will provide guidelines for developing protein nanoparticles for biotechnology fields that require size-controlled nanoparticles.

Small target detection is known to be a challenging problem. Inspired by the structural characteristics and physiological mechanism of eagle-eye, a miniature vision system is designed for small target detection in this paper. First, a hardware platform is established, which consists of a pan-tilt, a short-focus camera and a long-focus camera. Then, based on the visual attention mechanism of eagle-eye, the cameras with different focal lengths are controlled cooperatively to achieve small target detection. Experimental results show that the designed biological eagle-eye vision system can accurately detect small targets, which has a strong adaptive ability., submitted to 2021 Chinese Automation Congress (CAC 2021)

Cadmium (Cd) threatens rice quality and human health, yet this risk remains uncertain in paddy fields with high geological background of transportation and deposition. In this study, we collected 31 pairs of soil and rice grain samples in Doumen and Xinhui Districts in Guangdong province, China and investigated which factors controlled Cd bioavailability in soil and accumulation in rice. Soil samples were mostly acidic and contained a range of organic matter. Total Cd in soil varied from 0.10 to 1.03 mg kg− 1 and was positively correlated with those of calcium (Ca), manganese (Mn) and iron (Fe), suggesting that these elements shared same sources and Cd was most likely originated from parent material. The activity ratio (AR, CaCl2-extractable Cd/soil Cd) and bioconcentration factor (BCF, rice grain Cd/soil Cd) of Cd were negatively correlated with soil pH. The coupling relationship between soil and rice grain Cd could be described by a linear model, which was used to predict soil Cd threshold values to keep rice grain Cd concentration from exceeding the Chinese limit (0.2 mg kg− 1). In summary, Cd pollution was not very severe in the paddy soils of studied area but the risk could not be neglected when soil was acidified, which could increase Cd bioavailability and accumulation in rice grain.

Micron-sized lasers fabricated from upconverting nanoparticles (UCNP) coupled to whispering gallery mode (WGM) microresonators can exhibit continuous-wave anti-Stokes lasing useful for tracking cells, environmental sensing, and coherent stimulation of biological activity. The integration of these microlasers into organisms and microelectronics requires even smaller diameters, however, which raises threshold pump powers beyond practical limits for biological applications. To meet the need for low lasing thresholds and high fidelity fabrication methods, we use correlative optical and electron microscopy to uncover the nanoparticle assembly process and structural factors that determine efficient upconverted lasing. We show that 5 μm microspheres with controlled submonolayer UCNP coatings exhibit, on average, 25-fold lower laser thresholds (1.7 ± 0.7 kW/cm2) compared to the mean values of the lowest threshold UCNP lasers, and variability is reduced 30-fold. WGMs are observed in the upconversion spectra for TiO2-coated microspheres as small as 3 μm, a size at which optical losses had previously prevented such observations. Finally, we demonstrate that the WGM signatures of these upconverting microlasers can be imaged and distinguished through tissue-mimicking phantoms. These advances will enable the fabrication of more efficient upconverting lasers for imaging, sensing, and actuation in optically complex environments.

An experimental study of n-butanol pipe injection homogeneous charge compression ignition (HCCI) in combination with n-heptane in-cylinder direct injection (DI) is conducted on a modified engine. Since n-butanol does not have a good ignition property, it is preferable to utilize a better ignition fuel (n-heptane) to avoid HCCI combustion only controlled by chemical kinetics and to improve the ignition stability and combustion process. The effects of DI pressure, quantity, timing and intake temperature on RCCI combustion characteristics, thermal efficiency and emissions are studied. The results show that, the optimum DI pressure is 6 MPa. With the increase of DI quantity, peak in-cylinder pressure, peak pressure rise rate and peak heat release rate all increase and occur in advance, CA10 and CA50 occur earlier and combustion duration is shortened. DI timing has an obvious influence on combustion phase. It is concluded that, by adding n-heptane DI, HCCI combustion of n-butanol is improved, HC and CO emissions are reduced, and NOx emission is kept at a very-low level. A smaller cyclic variation is detected and more stable operation is achieved. To some extent, the combustion phase may be controlled, the indicated thermal efficiency is improved, and the operation range has been extended.

NiCrSiB modified layer was synthesized on Monel 400 by laser cladding, aiming at improving cavitation erosion and corrosion resistance. The microstructure, chemical composition, phase constituents and microhardness were investigated using scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), X-ray diffractometry (XRD) and microhardness tester. The cavitation erosion and corrosion behaviors of the modified layer were also evaluated using an ultrasonic vibrator and potentiodynamic polarization measurement, respectively. Experimental results show that by varying the laser fluence, a hard NiCrSiB modified layer with little airholes, cracks or other defects could be obtained. NiCrSiB modified layer is ~1.1 mm in thickness. The microstructure of the modified layer exhibits cellular dendrite, flake-like dendrite and multiple eutectic phase. The modified layer is mainly composed of γ-Ni solid solution, chromium carbide (Cr7C3 and Cr23C6) and Ni3B. The microhardness of the modified layer is ~6.8 times that of Monel 400 substrate. Both the cavitation erosion and corrosion resistance of the modified layer are improved. In the cavitation erosion test, the cumulative erosion loss and erosion loss rate of the modified layer are one order of magnitude lower than that of the substrate. In the electrochemical corrosion test, the corrosion potentials of the substrate and the modified layer are similar. The corrosion current densities of the substrate and the modified layer are 11.12 and 1.95 μA·cm−2, respectively. By comparing their corrosion current densities, the corrosion resistance of the modified layer is about 5.7 times that of the substrate.

In this paper, the operation parameters of a one-way spiral flow casting roller were simulated. Varies optimization proposals on the casting roller were brought out mainly focusing on the inlet and outlet cavities. Both the inlet pressure and drum rotational speed was found having direct influence on water delivery capacity. The water delivering capacity was increased when the inlet pressure was rising without varying the total pressure loss of the system. The water delivery capacity of the system was dropped after the initial growth with the increasing drum rotation speed. Study on operation parameters can provide technical guidance for the actual operation of casting roller. Additional guide vanes in the water inlet and outlet cavities were designed to improve the capacity of water delivery. The total pressure loss of optimized structure was reduced by 10%. The total water supply and pressure loss of the new designs were better than those of the current structure under the same conditions. Adding the vanes in outlet cavity was found having the most outstanding effect. In actual operation, the water supply pressure and the drum speed should be comprehensively determined to make the system more energy efficient

In this paper, a boundary scheme is proposed for the two-dimensional five-velocity (D2Q5) lattice Boltzmann method with heterogeneous surface reaction, in which the unknown distribution function is determined locally based on the kinetic flux of the incident particles. Compared with previous boundary schemes, the proposed scheme has a clear physical picture that reflects the consumption and production in the reaction. Furthermore, the scheme only involves local information of boundary nodes such that it can be easily applied to complex geometric structures. In order to validate the accuracy of the scheme, some benchmark tests, including the convection-diffusion problems in straight and inclined channels are conducted. Numerical results are in excellent agreement with the analytical solutions, and the convergence tests demonstrate that second-order spatial accuracy is achieved for straight walls, and the order of accuracy is between 1.5 and 2.0 for general inclined walls. Finally, we simulated the density driving flow with dissolution reactions in a two-dimensional cylindrical array, and the results agree well with those in previous studies

In this paper, a fractional step lattice Boltzmann method is proposed to model two-phase flows with large density differences by solving Cahn-Hilliard phase-field equation and the incompressible Navier-Stokes equations.In order to maintain a hyperbolic tangent property of the interface profile and conserve the volume, an interfacial profile correction term and a flux correction term are added into the original Cahn-Hilliard equation respectively. By using a fractional step scheme, the modified Cahn-Hilliard equation is split into two sub-equations. One is solved in the framework of lattice Boltzmann equation method. The other is solved by the finite difference method. Compared with the previous lattice Boltzmann methods, the proposed method is able to maintain the order parameter within a physically meaningful range, which is conductive to track the interface accurately. In addition, the multi-relaxation-time collision model and a high-order compact selective filter operation are employed to enhance the numerical stability. The proposed method can simulate two-phase fluid flows with the density ratio up to $1000$. In order to validate the accuracy and capability of the method, several benchmark problems, including single vortex deform of a circle, translation of a drop, Laplace-Young law, capillary wave and rising bubble with large density ratios, are presented. The results are in good agreement with the analytical solutions and the data in the literature for the investigated benchmarks., Comment: 32pages,13 figures

Mesoscale eddies exist almost everywhere in the ocean and play important roles in the ocean circulation of the world. These eddies may cause sound spread singular regions and bring great influences to the upwater ship and underwater aircraft. Due to the lack of hydrographic survey datasets, study of mesoscale eddies has been greatly restricted. Fortunately, satellite altimeter provided an effective way to study mesoscale eddies. An automatic detection algorithm is introduced to detect mesoscale eddies of specific intensity and spatial/temporal scale based on satellite sea surface height (SSH) data and the algorithm is applied in a strong eddy activity region: the South China Sea and the Northwest Pacific. The algorithm includes four steps. The first step is preprocessing of the SSH image, which includes elimination of error SSH data and interpolation. The second step is to detect suspected mesoscale eddies from preprocessed SSH images by dynamic threshold adjustment and morphological method, and the suspected mesoscale eddy detection includes two procedures: suspected mesoscale eddy core region detection and suspected mesoscale eddy brim extraction. The third step is to pick out mesoscale eddies satisfied with specified criteria from suspected mesoscale eddies. The criteria include three items, that is, intensity criterion, spatial scale, criterion and temporal scale criterion. The last step is algorithm performance analysis and verification. The algorithm has the capability of adaptive parameter adjustment, and can extract mesoscale eddies of interested intensity and spatial/temporal scale. The paper can provide a basis for analyzing space-time characteristics of mesoscale eddy in the South China Sea and the Northwest Pacific.

As wireless sensing has developed, wireless behavior recognition has become a promising research area, in which human motion duration is one of the basic and significant parameters to measure human behavior. At present, however, there is no consideration of the duration estimation of human motion leveraging wireless signals. In this paper, we propose a novel system for robust duration estimation of human motion (R-DEHM) with WiFi in the area of interest. To achieve this, we first collect channel statement information (CSI) measurements on commodity WiFi devices and extract robust features from the CSI amplitude. Then, the back propagation neural network (BPNN) algorithm is introduced for detection by seeking a cutting line of the features for different states, i.e., moving human presence and absence. Instead of directly estimating the duration of human motion, we transform the complex and continuous duration estimation problem into a simple and discrete human motion detection by segmenting the CSI sequences. Furthermore, R-DEHM is implemented and evaluated in detail. The results of our experiments show that R-DEHM achieves the human motion detection and duration estimation with the average detection rate for human motion more than 94% and the average error rate for duration estimation less than 8%, respectively.

Based on the vegetation inventory data,we investigated the density,storage and spatial characteristics and dynamics of vegetation carbon in Northwest Guangxi,China from 2005 to 2010,using biomass expansion factors and spatial analysis,respectively.The results showed that the total storage of vegetation carbon increased from 4.19 × 104 t to 4.27 × 104 t,about 1.84% per year.Similarly,the density of vegetation carbon also increased from 29.04t/hm2 to 29.57 t/hm2.Vegetation carbon density was highest(40 t/hm2) in National Nature Reserve.From 2005 to 2010,vegetation carbon density in the previously non-vegetated land increased significantly through artificial seeding,direct seeding,aerial seeding or natural germination.Vegetation carbon density of revegetated land through Conversion of Cropland into Forestland Program was also increased by 3.00 t/hm2.Vegetation carbon density from all types of forest stand was increased.With regards to the spatial distribution of carbon storage and density,the density was higher in the west,north,but lower in the middle-east,south.The average carbon density was more than 40 t/hm2 in the west but lower than 25 t/hm2 in the east and middle.The carbon storage and density in the karst areas and non-karst areas increased.Furthermore,vegetation carbon density in seven counties had increased to higher grade.Our study indicated that the carbon storage and density of vegetation in the study area was increased significantly and ecosystem conditions was improved through the application of policies of karst rocky desertification control,such as ecological migration and Conversion of Cropland into Forestland Program.

To investigate the effect of co-combustion ratio (CCR) on the combustion characteristics in the LNG/diesel dual-fuel engine, an electronically controlled common rail diesel engine is modified into an LNG/diesel dual-fuel engine by adding a set of LNG supply system and dual-fuel control system. The in-cylinder pressure, pressure rise rate (PPR) and heat release rate (HRR) are compared and analyzed under the conditions of different CCR at engine speed of 1400 r/min, engine load rate of 60%. The results show that the in-cylinder pressure, PRR and HRR of dual-fuel mode are higher than those of original mode and increase as the CCR increases.

Nitrogen is a major nutrient for all living organism on Earth and plays a central role in regulating the composition,structure,and function of ecosystems.Most nitrogen within terrestrial ecosystems is stored in soil organic matter.Total nitrogen in soils is mostly correlated with soil organic carbon content.The enrichment experiments of carbon dioxide further indicate that nitrogen limitation directly influences carbon sequestration by terrestrial ecosystems.Increased nitrogen availability normally increases productivity and biomass accumulation in ecosystems.However,few studies have been conducted to calculate soil nitrogen density and storage and to analyze its tempo-spatial variations in the Songnen Plain Maize Belt. Based on the second national soil survey of Jilin Province conducted around 1980 and field measurements of nitrogen density taken in years from 2003 to 2006,this study was devoted to calculate the density and total storage of nitrogen in top soils(0—20 cm) of the Songnen Plain Maize Belt and investigate the spatial and temporal variations of nitrogen density and possible underlying factors during the period from 1980 to 2005,including land-use types,original nitrogen content,and soil organic carbon changes.The totals of soil nitrogen storage were(40.47 ± 1.67)×108 kg and(40.28 ± 1.35)×108 kg in 1980 and 2005,respectively.The spatial patterns of soil total nitrogen density were similar in 1980 and 2005,higher in the centre and lower in the edge parts.The average of soil total nitrogen density over the entire study area changed only marginally in 25 years,about 0.31 kg/m2 in 1980 and 2005.However,the changes of soil total nitrogen density in 25 years varied with soils and land use types.Soil total nitrogen density increased in dark brown,paddy,and boggy soils.It did not change or even decreased in other soil types.Soil total nitrogen density changed a little in dry lands while it decreased obviously in paddy lands.The annual decrease rate of total nitrogen storage in top soils was 7.6×105 kg/a.The change of soil total nitrogen density in 25 years was negatively correlated with its initial value in 1980,but positively correlated with the change of soil organic carbon density.Soil nitrogen sequestration potential was generally defined as the difference between the equilibrium value of soil nitrogen storage and its initial value.The new equilibrium value of soil total nitrogen density was 0.32 kg/m2 in the study area.Without changes in land use and management after 1980,the soils of croplands in the study area has a potential of annually sequestrating nitrogen at the rate of 5.18×106 kg/a.However,the total nitrogen storage in 2005 was 1.2×108 kg lower than the potential of nitrogen sequestration.Actually,the application of nitrogenous fertilizer increased in the past 25 years according to the census data of Jilin Province.Therefore,reasonable fertilization should be practiced in this area.The management of croplands should be enhanced,especially for paddy lands converted from uplands.

α(β)-tetra-(methoxy-phenoxy)-zinc phthalocyanine are synthesized by employing 3(4)- nitrobenzene-1,2-dicarbonitrile as precursors. They are characterized by spectrum methods and elemental analysis. The UV-Vis spectrum, photoluminescence spectra of spin-coated film and solid pellet are compared. The electroluminescent devices are fabricated by using spin coating. The results indicate that the fluorescence of solid phthalocyanine has a red-shift of more than 145 nm compared to that in solution. The fluorescences are broader in solid state than that in solution. The fluorescence of β-substituted phthalcyanines has a more red-shift than α-substituted phthalcyanines. The electroluminescent spectra around 856 and 862 nm are consisted with the photoluminescence spectra of spin-coated film. The shorter inter-molecule space leads to the large red-shift of the fluorescence.

The hyperaccumulative plants of Solanum nigrum and Brassica juncea, and non-hyperaccumulative plants of maize (Zea mays) and radish (Raphanus sativus) were used to analyze the antioxidative system response to combined Pb and Cd pollution. The results show that leaf biomass for the hyperaccumulators, S. nigrum and B. junce, significantly decrease under the pollution, against a slight change in root and stem biomass under low Pb and Cd concentration. The biomass of nonhyperaccumulators, maize and radish, significantly decreases with increasing concentration of heavy metals. Hyperaccumulators’ superoxide dismutase (SOD) activity increases with increasing concentration of heavy metals in the soil. While peroxidase (POD) activities for the four plants are different, response of non-hyperaccumulators’ POD activities to heavy metal stress is the same and increases with increasing heavy metal concentration. Hyperaccumulators’s malondialdehyde (MDA) content also increases with increasing heavy metal concentration. B. juncea and radish have higher GSH content than the other two plants. For the hyperaccmulators, SOD, MDA, TSTA, GSH and PC are significantly correlated with heavy metal toxicity coefficient. POD and total GSH in maize significantly correlate with heavy metal toxicity coefficient, while TAST and PC in radish significantly correlate with heavy metal toxicity coefficient. The results indicate the detoxification mechanisms are different for plants. Therefore, it is important to further research on hyperaccumulator gene control and enzyme expression for a greater insight into detoxification mechanism.

Spatial variability in soil properties has long been observed within uniformly managed fields. Understanding the spatial characteristics of soil properties would be helpful in the development of site-specific management. Uniform management results in overapplication in areas with high nutrient levels and underapplication in areas with low nutrient levels. The objective of this study was to quantify the degree of spatial variability of soil properties. This is important to tobacco quality across flue-cured tobacco (Nicotiana tabacum) plantation fields. Fourteen soil properties were analyzed by geostatistical techniques. Soil organic matter (OM) had significantly positive correlations with active soil OM, total N (TN), available N, available phosphorus, available potassium, Cu, Fe, and Mn. Soil TN, Zn, cation exchange capacity, and silt showed strong spatial dependence, with nugget-sill ratios ranging from 3.39% to 23.43%. Other soil properties showed moderate dependence, with nugget-sill ratios of 30.87% to 49.99%. Spatial dependence ranged from 34.3 m (Zn) to 376.3 m (Mn). The OM contour map showed highest similarity with that of TN. Variography and kriging are useful tools for soil-sampling strategies and variable-rate application in site-specific farming.

Present nutrient management recommendations for flue-cured tobacco (Nicotiana tabacum) in central China are typically uniform for large regions. This results in overapplication in areas with high nutrient levels and underapplication in areas with low nutrient levels. Therefore, understanding the spatial variability of soil nutrients is essential in determining local fertilizer needs of tobacco. The objectives of this study were to (i) quantify the spatial variability of soil properties across tobacco plantation fields and (ii) generate contour maps for these variables. Soil samples (0-20 cm) were taken from 81 points on an approximately 100-m grid in March 2007 using global positioning system to define sample locations. Seven soil chemical properties and texture were analyzed by geostatistical techniques. Soil pH, total N, sand, and clay showed strong spatial dependence, with nugget/sill ratios ranging from 16% to 20%. Soil organic matter, available phosphorus (AP), available potassium (AK), cation exchange capacity, and silt showed moderate spatial dependence, with nugget/sill ratios ranging from 30% to 50%. Soil alkalytic N showed no spatial dependence (pure nugget effect) at the chosen sampling interval. Ranges of spatial dependence varied from 274 m (total N) to 1066 m (cation exchange capacity). The clearly patchy distribution and low extrinsic component of variability for AP and AK indicated that spatial distribution maps for AP and AK could be used for the basis of site-specific fertilizer application.

Yunnan Province is the main distributing area of Jatropha curcas L. This plant is abundant in several drainage areas of the dry-hot, dry-warm and sub-humid valleys in the south subtropical area of Yunnan Province. The seeds that were picked from trees blossoming between April and May and fructifying between September and October will have large seed yield and fine quality. For developing bio-diesel stock forest of J. curcas in areas with adaptive climate, seeding measures for afforestation should be taken and techniques on breeding, fast-growing, and high-yielding plantation cultivation are very important.

Since present fault prediction method of satellite attitude control system cannot describe and predict the nonlinear system effectively, a new method based on fuzzy-parity equation and grey GM (1, 1) model is presented in this paper. Firstly, fuzzy-parity equation and Kalman filter are utilized to extract the fault feature of satellite actuator. Translation transformation and buffer operator are adopted to process the fault feature so as to establish an equal dimension and new information GM (1, 1) model. Then the development trend of the fault feature is predicted and the confidence level of one-step prediction result is evaluated through the prediction grey-level. Simulations demonstrate that the proposed method can predict fault trend effectively and accurately.

Tissue cultured rose seedlings were carried into space by SHENZHOU-4 spacecraft and then used as the experimental material to investigate effects of the space environmental conditions on morphology, cytology, physiology and molecular biology of the seedlings. After loaded on the space flight, the plant's height, number of leaves, and fresh weight per seedling were all increased significantly compared to the ground controls. The content of chlorophyll was basically unchanged. In some cells, the ultrastructural changes involved twist, contraction and deformation of cell wall, curvature and loose arrangement of lamellae of some chloroplasts, and a significant increase in number of starch grains per chloroplast. In addition, the number of mitochondria increased, but some mitochondrial outer oxidase and catalyse, in rose leaves increased and the content of malondialdehyde decreased. In the RAPD analysis with 40 10-merprimers, 36 primers generated 148 DNA bands from both of the space flight treated see...

Bacillus subtilis AS1.398 was cultivated in a 11.5-L total volume external-loop airlift bioreactor with a low height-to-diameter ratio of 2.9 and a riser-to-downcomer diameter ratio of 6.6 for the production of protease from crude substrates with dregs. The influence of aeration rate, liquid volume, and sparger hole diameter on protease production was investigated. An average of 8197 u/mL protease activity was obtained after a total fermentation time of 32 h in the external-loop airlift bioreactor with a liquid volume of 8.5 L, air flow rate of 1.5 vvm, and sparger hole diameter of 1.5 mm. The addition of one stainless steel sieve plate in the riser of the airlift bioreactor increased productivity of protease. After 32 h of fermentation, an average of 8718 u/mL protease activity was achieved in the external-loop airlift bioreactor with one sieve plate and an air flow rate of 1.2 vvm, liquid volume of 8.5 L, and gas sparger hole diameter of 1.5 mm. This was 9.0% higher than the typical averages of about 8000 u/mL protease activity in the mechanically stirred tank bioreactors of the enzyme factory using the same microorganism. It is possible to make a scale-up of the external-loop airlift bioreactor and feasible to operate it for production of protease from crude substrate with dregs.

MAC protocol is an important problem in Underwater acoustic network. Many terrestrial wireless MAC protocol can’t work well in underwater because of long latency and limited bandwidth. In this paper, we modify the quiet duration in MACA-U using node position. The proposed MAC protocol is known as Geographical MACA(G-MACA). Simulation results in NS2 show that the throughput performance of G-MACA is much higher than that of MACA-U.

Underwater acoustic communication is one of the key technologies in various important research fields, such as ocean geography, offshore oil industry and defense. However, conventional system design can not achieve desirable results, since the underwater channel suffers a lot from multipath propagation and Doppler Effect. In this paper, we aim to introduce a type of coherent underwater acoustic communication system, which combine the joint synchronization and equalization scheme and the joint iterative equalization and decoding technique to combat the severe underwater environment mentioned above. The platform belongs to the physical layer and can take various high layer applications. The proposed system is tested in computer simulated scenarios and experimental data, both of which demonstrate good performance.

e-farm, as China's agricultural modernization effective way for the construction of new countryside in China has injected new vitality. The relevant policies in national support and guidance, the development of China's electronics farm has made remarkable achievements. However, due to China's electronics farm established not long, theoretical research is not mature, and the lack of practical experience for reference, in the promotion of the process there are many factors constraining their development.

China's electronic agriculture, tremendously promoted by the government, has made great progress, which offers support to speed up modernization of agriculture and brings new vigor to construction of the new countryside in China. Although its development is not long, China's electronic agriculture has made remarkable attainments. There is many a factor constraining the promotion of China's electronic agriculture due to its short duration of existence, immature theoretical research and insufficient reference of practical experience. The author, starting with analyzing bottleneck problems of current electronic agriculture like insufficient funds for development, weak construction of infrastructure, shortage of technical support, scarcity of talents, etc., explores approaches to development of China's electronic agriculture in order to provide theoretical directions for its further development.

The fast development of Internet stimulated the e-commerce to advance remarkably, but along with the evanescence of Internet myth, the e-commerce also entered a regulatory period. Security problems have become the bottleneck baffled the healthy growth of the e-commerce. Through analyzing the threats the e-commerce faced and the prerequisites to make the e-commerce system security, it is very easy to get such a conclusion that the application of encryption technology has a great influence on the e-commerce system security.

Stochastic resonance (SR) is a phenomenon that appeal's in nonlinear systems whereby weak input signals can be amplified and optimized by the assistance of noise. In the field of signal detection, the fundamental question is whether SR could be used to construct better detectors than the Neyman-Pearson (NP) detectors. Many researchers have pointed out that no gain should be expected from using a SR signal preprocessor because of the unwanted nonlinearities along the signal processing chain. We studied the SNR and the symmetry-breaking characteristic of the output probability density function (PDF) at the output of the SR. In order to avoid the nonlinearities between the input and output signal waveforms, we translate the input to zero frequency then through the SR processor. We called this procedure the optimum SR detector (OSRD) for its maximum output SNR and its avoidance from the nonlinearities. Simulations show that by using this kind of detector in some SR systems, the detection performance may be "'better" than the NP detector. An explanation is given and implies that the NP detector is still optimum.