废石-尾砂高浓度料浆的流变特性及屈服应力预测模型

为了研究矿山粗骨料(废石)充填的新模式,达到矿山绿色生产的需求.首先在大量试验的基础上给出了粗骨料料浆的高浓度特征.其次对大红山铜矿的废石与尾砂进行级配分析,选用最优配比m(废石)∶m(尾砂)为6∶4进行流变试验,分析其流变特性.最后应用双因素方差法分析了水泥添加量与质量浓度对屈服应力的影响.结果表明,废石-尾砂高浓度料浆属屈服-假塑性体,水泥添加量对屈服应力的影响更显著,屈服应力与水灰比及骨料体积分数存在定量的关系.在此基础上,建立了屈服应力的预测模型,预测结果的误差在5％以内.     

Enhancement of Rhodobacter sphaeroides growth and carotenoid production through biostimulation

Bacillus thuringiensis/cereus L2 was added as a biostimulant to enhance the biomass accumulation and carotenoid yield of Rhodobacter sphaeroides using wastewater as the culturing medium. Results showed that biostimulation could significantly enhance the R. sphaeroides biomass production and carotenoid yield. The optimal biostimulant proportion was 40 μL(about 6.4 × 105CFU). Through the use of biostimulation, chemical oxygen demand removal, R. sphaeroides biomass production, carotenoid concentration, and carotenoid yield were improved by 178%, 67%, 214%, and 70%, respectively. Theoretical analysis revealed that there were two possible reasons for such increases. One was that biostimulation enhanced the R. sphaeroides wastewater treatment efficiency. The other was that biostimulation significantly decreased the peroxidase activity in R. sphaeroides. The results showed that the highest peroxidase activity dropped by 87% and the induction ratio of the RSP_3419 gene was 3.1 with the addition of biostimulant. The enhanced carotenoid yield in R. sphaeroides could thus be explained by a decrease in peroxidase activity.     

Effect of cerium on photosynthetic characteristics of soybean seedling exposed to supplementary ultraviolet-B radiation

Effects of cerium （Ce^3＋） on photosynthetic characteristics were investigated by hydroponics under laboratory conditions when soybean seedlings were exposed to two levels of supplementary UV-B radiation. UV-B radiation badly inhibited the photosynthesis in soybean seedling, leading to a reduction in net photosynthetic rate （Pn）, Hill reaction activity, light saturated photosynthetic rate （Ps） and apparent quanta yield （AQY）, as well as the CO2 and light saturated photosynthetic rate （Pro） and carboxulation efficiency （CE）. On the contrary, Ce obviously promoted the photosynthesis of plants by increasing Hill reaction activity, accelerating electron transport and photophosphorylation, and enhancing carboxylation efficiency. For Ce＋UV-B treatments, the values of photosynthetic parameters were still lower than those of the control, but obviously higher than those of UV-B treatment. The results indicated that Ce alleviated the inhibition of UV-B radiation on the photosynthesis in soybean seedling to a certain extent. In correlating of Pn with Hill activity, AQY and CE, we found that the changes of photosynthetic rate were mainly influenced by the regulating effect of Ce on Hill activity and AQY at low level （0.15 W/m^2） of UV-B radiation, but were dominated by the regulating effect of Ce on CE at high level （0.45 W/m^2）. Thus, Ce could regulate many aspects in photosynthesis of soybean seedling under UV-B stress. The regulating mechanism was close related with the dosage of UV-B radiation.     

基于双剪屈服条件的输油管道腐蚀剩余强度可靠性研究

提出基于双剪屈服塑性极限条件的管道可靠性爆破压力可靠度模型,在基于剩余强度可靠性理论基础上,着重分析随机参数,即腐蚀深度、腐蚀长度和运行压力的分布情况,通过经典可靠性计算方法、JC法将非正态分布转化成标准正态分布,从而建立起基于双剪屈服条件的管道腐蚀可靠性计算模型。通过提取现场实验数据进行验算,其结果表明:双剪屈服强度理论算得的爆破压力更接近实验结果,该方法降低API579的保守性,大大提高了可靠性的计算精度。     

The combination of subsoil and the incorporation of corn stover affect physicochemical properties of soil and corn yield in semi-arid China

ABSTRACT

The main objective of this study was to investigate the effects of combining subsoil and incorporation of corn stover on soil profile, soil physicochemical properties, and corn yield. A five-year field trial was conducted that consisted of two treatments arranged in a completely random design and replicated three times. Two soil management operations were tested: subsoil + corn stover incorporation (plow construction [PC] treatment) and conventional rotary tillage (control check [CK] treatment). Compared with rotary tillage, it was found that combining subsoil and corn stover incorporation significantly affected corn grain yield in all seasons. Further, combining subsoil and corn stover incorporation significantly increased the thickness of the plow layer, quantity of plow layer soil, thickness of the plow pan and soil bulk density, as well as soil organic matter, available nitrogen, available phosphorus, and available potassium. Evidence indicates that reconstructing the soil plow layer through combination of subsoil and corn stover incorporation improved soil structure, nutrient content, and corn yield. It is of interest that farmers are now applying subsoil and returning crop straw instead of solely relying on rotary tillage.     

Flood Disaster Reduction in China''''s Major Cereal Production Areas

1The Agricultural Resources and Yielding Status of the Major Cereal ProductionAreasNEC,RBHHH and ML RYR are the three major areas for agricultural and cereal production inChina and the national bases for growing commodity grain with first priority.Especially,theThree-River Plain and Songhuajiang-Nenjiang Plain in NEC,the alluvial plain of the Huanghe,Haihe and Huaihe rivers in RBHHH and the plain of two rivers (Hanshui and Huaihe) and threelakes (Poyang,Dongting and Taihu) in …     

SENSITIVITY OF GROUNDWATER FLOW MODELS TO VERTICAL VARIABILITY OF AQUIFER CONSTANTS1

ABSTRACT: The Ogallala aquifer in the Oklahoma Panhandle is in need of better management because of increased groundwater demand which has caused declines in static water levels at an alarming rate. A groundwater management computer model was developed for the Ogallala aquifer in the Texas Panhandle and treats the aquifer as a homogeneous system. In this study, the computer model has been modified in order to evaluate the effects of vertical layering on semi-static water level changes which occur during the dewatering of a single unconfined aquifer. The modified model was applied to a study area near Guymon, Oklahoma, using both the homogeneous and the multilayered cases. The aquifer is characterized by a saturated thickness of 400 feet. The accumulated drawdown values of the homogeneous and the multilayered cases demonstrate that an average difference of approximately 22% of the original saturated thickness occurs between the two cases before the base of the aquifer is encountered. Approximately 25% more time is required to dewater the layered aquifer. Thus, vertical variations of lithology in an aquifer such as the Ogallala should be considered when prediction is made relative to groundwater management.     

EFFECTS OF SIMULATED CLOUD SEEDING ON STREAMFLOW OF SELECTED WATERSHEDS IN PENNSYLVANIA1

A mathematical model was developed to simulate the hydrologic behavior of five small watersheds in central Pennsylvania. Continuous hydrographs for the 6-month period, April to September 1964, were simulated. Synthesized rainfall cycles consisting of increasing rainfall by 10, 20, and 30 percent to simulate the effects of cloud seeding were processed through the watershed model to determine the effects on low flow augmentation. Other rainfall cycles used consisted of increasing every third storm by 30 percent and of developing a rainfall cycle by processing daily radiosonde data through a mathematical cumulus cloud model to obtain a prediction of rainfall following seeding. A comparison of actual and predicted hydrographs indicated that simulated cloud seeding resulted in significant monthly and seasonal water yields. In general, the results of the study appear to indicate that on a theoretical basis cloud seeding would be a feasible method of augmenting low stream-flow during the summer months on watersheds in the northern Appalachian region.     

Management provoked conflict in fisheries

Fishery management concepts incorporate a number of value judgements about what social goals are right for a fishery. These value judgements result in optimizing some goals over others. Since the public, fishermen, and consumers weight goals differently than managers, frustration and conflict result. The correspondence between social goals specified by the public and those inherent in management concepts needs to be evaluated.     

OPERATING POLICIES FOR A SURFACE/GROUND WATER SYSTEM1

The simulation of the conjunctive use of a surface reservoir and a limestone aquifer is described. The potential yields from each of the sources are of the same order. An important feature of the aquifer is that if the pumpage is reduced, much of the excess water is lost through springs. Five different operating policies are considered which determine whether pumpage should be taken from the reservoir or aquifer. The total safe yields for the historic period 1961–1977 are estimated for each policy and their relative advantages and disadvantages are discussed. The simulation is also carried out for 100 years of generated data to discover the long term consequences.