基于多智能体的制造系统生产控制建模研究

为提高制造系统生产控制的性能,建立了基于多智能体系统的混合控制模型。该模型把生产控制系统分为管理智能体层、单元智能体层和执行智能体层。管理智能体层负责调度和协调各单元智能体,并对所有智能体进行管理;单元智能体层中的各单元智能体间通过公用数据库相互协作;执行智能体对制造系统内的硬件负责,它们根据局部的本地资源信息及当前状态,接收发布的任务,并对其求解。同一层次的智能体之间是分布式结构。采用基于多智能体的混合控制模式,提高了制造系统生产控制的实时性和灵活性。通过激光拼焊生产系统中的试验,验证了该模型的有效性。

Control mechanisms for gas hydrate production by depressurization in different scale hydrate reservoirs

The methane hydrate was formed in a pressure vessel 38 mm in id and 500 mm in length. Experimental works on gas production from the hydrate-bearing core by depressurization to 0.1, 0.93, and 1.93 MPa have been carried out. The hydrate reservoir simulator TOUGH-Fx/Hydrate was used to simulate the experimental gas production behavior, and the intrinsic hydration dissociation constant (K-0) fitted for the experimental data was on the order of 104 mol m(-2) Pa-1 s(-1), which was one order lower than that of the bulk hydrate dissociation. The sensitivity analyses based on the simulator have been carried out, and the results suggested that the hydrate dissociation kinetics had a great effect on the gas production behavior for the laboratory-scale hydrate-bearing core. However for a field-scale hydrate reservoir, the flow ability dominated the gas production behavior and the effect of hydrate dissociation kinetics on the gas production behavior could be neglected.

Reducing H2S production by O-2 feedback control during large-scale sewage sludge composting

Hydrogen sulfide (H2S) production patterns and the influence of oxygen (O-2) concentration were studied based on a well operated composting plant. A real-time, online multi-gas detection system was applied to monitor the concentrations of H2S and O-2 in the pile during composting. The results indicate that H2S was mainly produced during the early stage of composting, especially during the first 40 h. Lack of available O-2 was the main reason for H2S production. Maintaining the O-2 concentration higher than 14% in the pile could reduce H2S production. This study suggests that shortening the interval between aeration or aerating continuously to maintain a high O-2 concentration in the pile was an effective strategy for restraining H2S production in sewage sludge composting. (C) 2010 Elsevier Ltd. All rights reserved.

Fourth order accurate compact scheme with group velocity control (GVC)

For solving complex flow field with multi-scale structure higher order accurate schemes are preferred. Among high order schemes the compact schemes have higher resolving efficiency. When the compact and upwind compact schemes are used to solve aerodynamic problems there are numerical oscillations near the shocks. The reason of oscillation production is because of non-uniform group velocity of wave packets in numerical solutions. For improvement of resolution of the shock a parameter function is introduced in compact scheme to control the group velocity. The newly developed method is simple. It has higher accuracy and less stencil of grid points.

Mass rearing of Aphidius gifuensis (Hymenoptera : Aphidiidae) for biological control of Myzus persicae (Homoptera : Aphididae)

The green peach aphid, Myzus persicae, is a major pest of tobacco, Nicotiana tabacum, in Yunnan province, China, where its control still depends on the use of insecticides. In recent years, the local government and farmers have sought to improve the biological control of this tobacco pest. In this paper, we present methods for mass rearing Aphidius gifuensis, a dominant endoparasitoid of M. persicae on tobacco plants in this region. The tobacco cultivar K326 (N. tabacum) was used as the host plant and M. persicae as the host insect. In the greenhouse, we collected tobacco seedlings for about 35 days (i.e., until the six-true-leaf stage), transferred them to 7.5-cm diameter pots, and kept these plants in the greenhouse for another 18 days. These pots were then transferred to an insectary-greenhouse, where the tobacco seedlings were inoculated with five to seven wingless adult M. persicae per pot. After 3 days, the infested seedlings were moved to a second greenhouse to allow the aphid population to increase, and after an additional 4 +/- 1 days when 182 +/- 4.25 aphid adults and nymphs were produced per pot, they were inoculated with A. gifuensis. With this rearing system, we were able to produce 256 +/- 8.8 aphid mummies per pot, with an emergence rate of 95.6 +/- 2.45%; 69% were females. The daily cost of parasite production (recurring costs only) was US$ 0.06 per 1000 aphid mummies. With this technique, we released 109 800 parasitoids in 1998, 196 000 in 1999, 780 000 in 2000, and 5 600 000 in 2001 during a 2-month period each year This production method is discussed with respect to countrywide usage in biological control and integrated control of M. persicae.

Development and use of parasitoids (Hymenoptera : Aphidiidae & Aphelinidae) for biological control of aphids in China

A review of aphid parasitoids in China with special emphasis on their production, utilization, and conservation is presented with a brief history of Chinese biological control. Twenty genera, 99 species of Aphidiidae and two genera, 11 species of Aphelinidae were recorded in China. Each parasitoid is listed with a brief description of aphids, host plants, areas of study such as taxonomy, biology, bionomics, geographic distribution, rearing, and literature citations. Achievements, status, and problems in aphid parasitoid production, utilization, conservation, and future prospects are detailed for dominant aphid parasitoids such as Aphidius gifuensis Ashmead, A. ervi Haliday and Aphelinus mali Haldeman. Finally, opportunities and challenges of commercialization commercialization of natural enemies, especially aphid parasitoids, in China, are analyzed and discussed.

Detection of serum and mucosal antibody production and antibody secreting cells (ASCs) in large yellow croaker (Pseudosciaena crocea) following vaccination with Vibrio harveyi via different routes

The kinetics of mucosal and serum antibody response is well as antibody secreting cells (ASCs) production were studied in large yellow croaker following vaccination with inactivated Vibrio harveyi by different routes: oral administration. intraperitoneal (IP) injection and immersion. Indirect ELISA was used to measure the antibody level in serum and cutaneous mucus, and ELISPOT was used to monitor the ASCs derived from gill, blood and head kidney. The data demonstrated that IP injection resulted in the highest antibody levels in the systemic circulation, whereas immersion induced significant antibody levels in mucous. As for the ASCs response, IP injection induced high numbers of ASCs in the head kidney and blood; oral intubation only induced a slight ASCs response in the head kidney: immersion induced a much stronger ASCs response in the gill. These results indicate that mucosal antibodies following immersion immunization are independent of a systemic response and more sensitive, since it could be triggered earlier than serum antibodies. The mucosal antibodies following IP injection immunization may depend oil a systemic immune response. The protective effects of the three vaccination methods were compared by challenging with live V. harveyi. Survival of the three groups of vaccinated fish varied front 40 to 60%. while 100% mortality was found in control fish. Compared with IP and oral vaccination, immersion stimulated higher specific antibody titers in the mucosal system and achieved similar protection, so it is in effective and efficient method for immunizing a large number of fish against V harveyi (C) 2008 Elsevier B.V. All rights reserved.

Effects of gibberellin A(3) on growth and microcystin production in Microcystis aeruginosa (cyanophyta)

Environmental. factors that affect the growth and microcystin production of microcystis have received worldwide attention because of the hazards microcystin poses to environmental safety and public health. Nevertheless, the effects of organic anthropogenic pollution on microcystis are rarely discussed. Gibberellin A(3) (GA(3)) is a vegetable hormone widely used in agriculture and horticulture that can contaminate water as an anthropogenic pollutant. Because of its common occurrence, we studied the effects of GA3 on growth and microcystin production of Microcystis aeruginosa (M. aeruginosa) PCC7806 with different concentrations (0.001-25mg/L) in batch culture. The control was obtained without gibberellin under the same culture conditions. Growth, estimated by dry weight and cell number, increased after the GA3 treatment. GA3 increased the amounts of chlorophyll a, phycocyanin and cellular-soluble protein in the cells of M. aeruginosa PCC7806, but decreased the accumulation of water-soluble carbohydrates. In addition, GA3 was observed to affect nitrogen absorption of the test algae, but to have no effect on the absorption of phosphorus. The amount of microcystin measured by enzyme-Linked immunosorbent assay (ELISA) increased in GA3 treatment groups, but the stimulatory effects were different in different culture phases. It is suggested that GA3 increases M. aeruginosa growth by stimulating its absorbance of nitrogen and increasing its ability to use carbohydrates, accordingly increasing cellular pigments and thus finally inducing accumulation of protein and microcystin. (C) 2007 Elsevier GmbH. All rights reserved.

Control of cocklebur seed germination by nitrogenous compounds : Nitrite, nitrate, hydroxylamine, thiourea, azide and cyanide

Germination of non-dormant upper cocklebur (Xanthium pinsylvanicum Wallr.) seeds was stimulated by not only CS(NH2)2 but also NH2OH, KCN and NaN3. This stimulation was not via the enhancement of aerobic C2H4 production. NH2OH, KCN and NaN3 in certain concentrations promoted the initial growth of axial and/or cotyledonary parts, but the degree of growth promotion by NH2OH, NaN3 and KCN was slight compared with that by CS(NH2)2. As in the case of CS(NH2)2, however, the germinationstimulating effect of NH2OH disappeared rapidly as the preceding imbibition period was prolonged. In contrast, KCN and NaN3 were still effective in stimulating the germination of aged seeds maintained on a water substratum, as previously seen with anaerobiosis. Anaerobic induction was enhanced not only by NaN3 and KCN but also by NH2OH, KNO3, KNO2 CO(NH2)2 and CS(NH2)2 applied during the anaerobic treatment, but without causing an increase in anaerobic production of C2H4. Furthermore, KCN and NaN3, given prior to the anaerobic treatment acted additively with anaerobic induction. The germination-stimulating actions of nitrogenous compounds are discussed in comparison with those of C2H4 and anaerobiosis.

Rare Earth Pyrophosphates: Effective Catalysts for the Production of Acrolein from Vapor-phase Dehydration of Glycerol

Vapor-phase dehydration of glycerol to produce acrolein was investigated at 320 A degrees C over rare earth (including La, Ce, Nd, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, Lu) pyrophosphates, which were prepared by precipitation method. The most promising catalysts were characterized by means of XRD, FT-IR, TG-DTA, BET and NH3-TPD measurements. The excellent catalytic performance of rare earth pyrophosphate depends on the appropriate surface acidity which can be obtained by the control of pH value in the precipitation and the calcination temperature, e.g. Nd-4(P2O7)(3) precipitated at pH = 6 and calcined at 500 A degrees C in the catalyst preparation.

Cultivation of the intertidal brown alga Hizikia fusiformis (Harvey) Okamura: mass production of zygote-derived seedlings under commercial cultivation conditions, a case study experience

Mariculture of the brown alga Hizikia fusiformis (Harvey) Okamura as an export-oriented human food has been there more for than 20 years in China. It is now one of the five major farmed algal species along the Chinese coast. Stable and sufficient supply of young seedlings for scaling up the cultivation has been a problem throughout the farming history of this species due to the unique dioecious life cycle and relatively short time window of sexual reproduction in nature. These two factors led to a practical difficulty in obtaining zygotes at identical developmental stage in viable amounts for seedling production. A key solution to this problem is to control the synchronization of the receptacle development and to realize the simultaneous discharge of male and female gametes, such that the fertilization rate could be greatly enhanced. Focusing on one of the farmed populations in this report, we present our results on mass production of seedlings using the synchronization technique on a large scale performed in 2007. Totally 5.5 hundred million embryos were obtained from 100 kg female sporophytes. The seedlings were raised up to 3.5 mm in length in greenhouse tanks over a month and were further grown in open sea for over 3 months at two experimental sites. The success of mass production of seedlings in this alga helped to lay the basis for future trials in other species in the genus of Sargassum that have identical life cycle.

Enrichment and hydrogen production by marine anaerobic hydrogen-producing microflora

Acid, alkali, heat-shock, KNO3 and control pretreatment methods applied to anaerobic sludge were evaluated for their ability to selectively enrich the marine hydrogen-producing mixed microflora. Seawater culture medium was used as the substrate. The hydrogen yield of pretreated microflora was higher than that of the un-pretreated control (P < 0.05). Among the pretreatment methods studied, heat-shock pretreatment yielded the greatest hydrogen production, which was 14.6 times that of the control. When the effect of initial pH on hydrogen production of heat-shock pretreated samples was studied, hydrogen was produced over the entire pH range (pH 4-10). The hydrogen yield peaked at initial pH 8 (79 mL/g sucrose) and then steadily decreased as the initial pH increased. Sucrose consumption was high at neutral initial pH. During the process of hydrogen production, pH decreased gradually, which indicated that the acquired microflora consisted of acidogenic bacteria.

Production of a base population and its responses to F-1 selection in the bay scallop, Argopecten irradians irradians Lamarck (1819)

A base population of the bay scallop, Argopecten irradians irradians Lamarck, was produced by crossing two cultured bay scallop populations. After 1 year of rearing, the top 10% truncation selection of the top 10% (i=1.755) was carried out in the base population of about 1300 adults. A control parental group with a an identical number to the select parental group was randomly selected from the entire population before isolation of the select parental group. The result showed that, at the larval stage, the growth rate of larvae in the selected line was significantly higher than that of the control (P < 0.05), and that the genetic gain was 6.78%. Owing to the lower density of control at the spat stage, the mean shell length of the control line was larger than that of the select line at day 100. When the same density was adjusted between two lines in the grow-out stage (from day 100 to 160), the daily growth rate of the selected line was significantly higher than that of the control line (P < 0.05). Survival of the select line was significantly larger than that of the control line in the grow-out stage. In conclusion, the results obtained from this experiment indicate that selective breeding from a base population with a high genetic diversity established by mass spawning between different populations appears to be a promising method of genetic improvement in bay scallop, A. irradians irradians Lamarck.

Effects of vegetation control on ecosystem water use efficiency within and among four grassland ecosystems in China

Through 2-3-year (2003-2005) continuous eddy covariance measurements of carbon dioxide and water vapor fluxes, we examined the seasonal, inter-annual, and inter-ecosystem variations in the ecosystem-level water use efficiency (WUE, defined as the ratio of gross primary production, GPP, to evapotranspiration, ET) at four Chinese grassland ecosystems in the Qinghai-Tibet Plateau and North China. Representing the most prevalent grassland types in China, the four ecosystems are an alpine swamp meadow ecosystem, an alpine shrub-meadow ecosystem, an alpine meadow-steppe ecosystem, and a temperate steppe ecosystem, which illustrate a water availability gradient and thus provide us an opportunity to quantify environmental and biological controls on ecosystem WUE at different spatiotemporal scales. Seasonally, WUE tracked closely with GPP at the four ecosystems, being low at the beginning and the end of the growing seasons and high during the active periods of plant growth. Such consistent correspondence between WUE and GPP suggested that photosynthetic processes were the dominant regulator of the seasonal variations in WUE. Further investigation indicated that the regulations were mainly due to the effect of leaf area index (LAI) on carbon assimilation and on the ratio of transpiration to ET (T/ET). Besides, except for the swamp meadow, LAI also controlled the year-to-year and site-to-site variations in WUE in the same way, resulting in the years or sites with high productivity being accompanied by high WUE. The general good correlation between LAI and ecosystem WUE indicates that it may be possible to predict grassland ecosystem WUE simply with LAI. Our results also imply that climate change-induced shifts in vegetation structure, and consequently LAI may have a significant impact on the relationship between ecosystem carbon and water cycles in grasslands.