Flash flood simulation and valve behavior of Mytilus galloprovincialis measured with Hall sensors

Mussels close their shell as a protective strategy and the quantification of this behavioral marker may represent an alarm signal when they are exposed to environmental stressors. In the present study, we investigated the ability of the Mediterranean mussel Mytilus galloprovincialis to recover and then the resilience or inertia of valve activity after a pulsing exposition to diverse levels of salinity (5, 10, 20, and 35 PSU as reference value). The trial simulated an event of drastic and sudden reduction of seawater salinity thus mimicking an event of flash flood from intense rain. Valve gaping and movements were measured in continuous cycle for 10 days using a customized magneto-electric device which uses Hall sensors. Results showed that under normal conditions of salinity (35 PSU), the general pattern of valve movements was a continuously open state with sporadic spikes indicating a closing motion. At salinity of 5, PSU mussels reacted by closing their valves, leading to a 77% mortality on the 4th day. At salinity of 10, PSU animals were observed with closed valves for the entire duration of the exposure and no mortality occurred, they showed a significant reduction in the valve activity once the reference value of salinity was re-established. In contrast, salinity of 20 PSU did not trigger a significant behavioral response. Interestingly, there no define rhythms of valve movements were recorded during salinity challenges.     

霍尔效应测量中的系统误差及其处理

本文对霍尔效应测量中的热能流引起的不等位电势误差提出了自己的见解,然后着重研究消除系统误差的方法,并对实验结果进行了评述.     

汽车发电机定子铁芯卷叠生产线自动控制系统的研制

汽车发电机定子铁芯卷叠新工艺生产线自动控制系统由自行设计的专用微机和日本三菱F—60可编程序控制器组成。以 Z80 CPU 为核心的专用微机具有计数带料长度、厚度实时检测及根据带料厚度变化自动决定带料长度等功能。F—60可编程序控制器能完成从带料至加工成定子铁芯成品整个工艺过程的自动控制,实现了高速冲裁机、卷绕专机之间及其与其它各台专机之间的协调控制,系统自动化程度高,控制灵敏、可靠。     

基于霍尔传感器反馈的AVR单片机直流电机伺服系统设计

文章介绍了以ATmega8单片机作为核心控制芯片,采用PWM控制方式,应用PID控制算法,通过直流电机驱动芯片LM298和霍尔传感器实现的速度反馈闭环控制系统,给出了硬件电路和相应的软件设计.     

高产优质转基因杂交抗虫棉合丰202的选育

合丰202是以农大326×GK12杂交后代的高代转基因抗虫稳定系145系为母本,以高产优质的206系（冀棉20号纯系）为父本,经过杂交选育而成的高产、优质、转基因杂交抗虫棉品种。该品种抗棉铃虫、抗枯萎病、高产、优质、杂种优势强、适应性广,适宜在黄河流域的河北中南部,山东北部、西北、西南部,河南北部、东部、东南部,安徽淮河以北,江苏淮河以北,山西南部和天津棉区种植。     

小麦新品种豫农202种子田中杂株类型的鉴定

以小麦新品种豫农202种子田中的88个杂株为材料,对其后代的株高、成穗数、旗叶长、旗叶宽、倒二叶长、脖长、倒一节长、倒二节长、穗长、小穗数、主茎穗粒数等11个农艺性状指标进行测定,通过农艺性状的遗传差异分析探讨杂株产生的原因.结果表明,在杂株后代农艺性状的遗传差异基础上,利用形态标记可以将豫农202种子田中的88份杂株材料分成剩余变异类、天然异交类和异品种(系)类3大类.形态标记基本上可以区分小麦杂株类型.     

中早熟春玉米新品种赤单202的选育研究

中早熟春玉米新品种赤单202是由赤峰市农科所玉米研究中心用自选半马齿型自交系赤126为母本,以国外自交系Mo17为父本杂交育成,1999年通过内蒙古自治区农作物品种审定委员会审定命名.该品种在赤峰种植生育日数为118 d,需≥10℃积温2 650℃·d,具有产量水平高抗病、抗倒伏及抗旱耐瘠能力强,适应性广的特点.适应在内蒙古干旱区域中肥水地区种植.到2000年赤单202已在内蒙的赤峰市、兴安盟、呼市、乌盟、伊盟、黑龙江的肇东、呼兰等地区累计面积0.85万hm2,已成为部分地区的主栽品种。     

烤烟新品种云烟202的烘烤特性初报

研究了烤烟新品种云烟202成熟烟叶在烘烤过程中水分及叶绿素含量的变化。结果表明,云烟202成熟鲜烟叶的叶绿素含量明显低于K326和红花大金元,含水量低于K326,高于红花大金元;在烘烤过程中的变黄阶段叶绿素的降解速度快于K326和红大,烟叶全黄所需时间,接近K326,明显短于红花大金元,失水速度慢于红花大金元,快于K326;在定色和干筋阶段,烟叶失水速度快,叶肉的干燥时间短于K326而长于红花大金元。烟叶表现容易烘烤。     

Associations Between Oil and Gas Wells and Arthropod and Vegetation Communities in the Southern Plains

Understanding how energy infrastructure affects local biodiversity and soil characteristics is important for informing restoration and management. However, the rapid rate of modern oil and gas development is beyond the limit of current knowledge and mitigation strategies. In a mixed-grass prairie in western Oklahoma, we assessed the presence and directionality of biodiversity and environmental gradients associated with energy development in an observational framework. Specifically, we sampled arthropods, vegetation, soil temperature, and soil moisture on the edge of active oil well pads and at 1 m, 10 m, and 100 m away from the well pad. Though variable, the abundance and biomass of most arthropod orders was lower on the pad and 1 m away compared with 10 m and 100 m away, suggesting that the pad itself negatively influenced arthropods but that these effects were limited in spatial extent. However, vegetation structure and composition varied more extensively. Vegetation height, shrub cover, and warm season grass cover increased sixfold, threefold, and fourfold, respectively, from on the oil pad to 100 m away. Forb cover was 5 × higher at 10 m from the well pad than on the pad, 1 m away, and 100 m away from the pad. Soil surface temperature was lower at sites farther from well pads, but we found no relationship between soil moisture and distance from well pad. Well pad effects on arthropods and soil temperature appear to be limited to the pad itself, though long-term changes in vegetation structure extend significantly beyond the well footprint and demand a better understanding of the effectiveness of restoration activities around well pads.     

Nondestructive Estimation of Standing Crop and Fuel Moisture Content in Tallgrass Prairie

Accurate estimation of standing crop and herbaceous fuel moisture content (FMC) are important for grazing management and wildfire preparedness. Destructive sampling techniques have been used to accurately estimate standing crop and FMC, but those techniques are laborious and time consuming. Existing nondestructive methods for estimating standing crop in tallgrass prairie have limitations, and few studies have examined nondestructive estimation techniques for FMC in this environment. Therefore, our objective was to develop robust models for nondestructive estimation of standing crop and FMC in tallgrass prairie. We calibrated and validated stepwise multiple linear regression (SMLR) and artificial neural network (ANN) models for standing crop and FMC using data collected in tallgrass prairies near Stillwater, Oklahoma. Day of year (DOY), canopy height (CH), Normalized Difference Vegetation Index (NDVI), and percent reflectance in five wavelength bands were candidate input variables for the models. The study spanned two growing seasons and nine patches located within three pastures under patch burn management, and the resulting data set with > 3 000 observations was split randomly with 85% for model calibration and 15% withheld for validation. Standing crop ranged from 0 to 852 g m^? 2, and FMC ranged from 0% to 204%. With DOY, CH, and NDVI as predictors, the SMLR model for standing crop produced a root mean squared error (RMSE) of 119 g m^? 2 on the validation data, while the RMSE of the corresponding ANN model was 116 g m^? 2. With the same predictors, the SMLR model for FMC produced an RMSE of 26.7% compared with 23.8% for the corresponding ANN model. Thus, the ANN models provided better prediction accuracy but at the cost of added computational complexity. Given the large variability in the underlying datasets, the models developed here may prove useful for nondestructive estimation of standing crop and FMC in other similar grassland environments.