Modelling coupled peach tree-aphid population dynamics and their control by winter pruning and nitrogen fertilization

Nitrogen fertilization and winter pruning are commonly used to control crop production in peach [Prunus persica (L.) Batsch] orchards. They are also known to affect the dynamics of Myzus persicae (Sulzer) (Homoptera: Aphididae) aphid populations via bottom-up regulation processes. Interactions between crops and pests can cause complex system behaviour in response to management practices. An integrated approach will therefore improve the understanding of the effects of these two cultural practices on aphid and peach performances.We developed a simulation model that describes the cultural control of interacting peach tree and aphid population dynamics. It uses the principles of common trophic models while gathering available knowledge and explicit assumptions on peach and aphid functioning and the effects of cultural practices.The model was able to qualitatively reproduce the system behaviour observed in the field. It accounted for actions and feedback such as stimulation of foliar growth by winter pruning, consecutive aphid population increase, subsequent damage to foliage, and partial compensatory growth of foliage. The model also reproduced low losses in fruit production due to aphid infestations. However, it called for further integration of ‘long-term’ effects. Analysis of the model showed the complexity of peach tree and aphid responses to leaf N × winter pruning interactions. Simulations indicated that fruit production losses remained low within a range of realistic values of leaf N and pruning intensity, whereas manipulating peach and aphid dynamics, their interactions and their relationships to practices could result in higher losses.The model is useful to evaluate the relevance of cultural practices for a bottom-up regulation of aphid dynamics in crop-pest management. After considering other control methods and fruit quality, it can be used to find a combination of practices that optimises trade-offs between fruit production and environmental conservation goals. A modelling approach that links crop growth and pest population dynamics and integrates management practice effects has strong potential for improving crop-pest management in an integrated crop production context.     

豆科牧草对4种农田常见杂草和水稻化感作用的研究

采用室内生测试验评价了白三叶、紫花苜蓿和毛苕子等3种豆科牧草新鲜茎叶的水浸提液对狗牙根、稗草、马唐和牛筋草等4种农田常见杂草种子萌发和幼苗生长的化感作用。利用盆栽试验研究3种豆科牧草的茎叶按不同比例与土混匀后对水稻秧苗生长的影响。结果表明：供体豆科牧草茎叶的水浸提液对狗牙根、稗草、马唐和牛筋草等的萌发率和幼苗生长均有不同程度的抑制作用,且随着水浸提液质量浓度的增加其抑制作用增强。浸提液质量浓度为0.1 g.mL-1时,毛苕子对稗草种子萌发的抑制作用强于其它3种,抑制率达50.8%;毛苕子对牛筋草幼苗根的抑制作用最强,抑制率达59.9%;白三叶对稗草幼苗茎的抑制率达54.3%。同时将豆科牧草的m（新鲜茎叶）-m（土）为1%和2%时,对水稻的苗高和地上部分的生物量有促进作用,3%时则抑制了水稻的生长。研究表明：施用适量的豆科牧草可以促进水稻生长,同时可有效控制稻田杂草。     

一种非平稳随机振动试验控制系统设计

目的 实现非平稳随机振动试验控制,在传统随机振动试验控制理论基础上,提出一种针对非平稳连续振动方式下的随机试验控制方法.方法 将均方根时变的非平稳随机振动过程近似等效为一个均方根和PSD谱的乘积模型,通过实时计算归一化的驱动谱,利用均方根实时跟随控制策略,更新驱动信号,实现连续非平稳随机振动控制.利用软件编程实现控制算...     

乐山市臭氧生成与前体物之间的关系及其敏感性和控制分析

为初步了解乐山市臭氧生成的主要特征和科学管控,采用Pearson相关性分析法分析一年来臭氧及其前体物之间的相关性,并采用OBM模式和VOCS/NOX比值法分别讨论臭氧生成的敏感性和控制性特征.结果 表明:乐山市氮氧化物与臭氧在夏秋两季呈现正相关,在春冬两季呈负相关;从臭氧的敏感性分析得出臭氧生成潜势PO3-NO:夏季＞...     

Synergy Between Visual and Auditory Signals and Its Influence on the Follow-Up Regulation Quality

The study aimed at verifying a hypothesis that supporting a visual signal of regulation deviation with an auditory one could improve the quality of regulation; the operator would have better information on machine operation. A special simulator was applied to follow-up tracking with a manual lever which controlled vertical movements of a cursor on a monitor screen. Simultaneously with visual information on screen, the operator was provided with an auditory deviation signal of pre-determined characteristics. 33 young males underwent the test. It was found that supporting a visual signal with an auditory one resulted in an improvement in the regulation quality by 5-6%, which proved synergy between those signals. The results may be used in designing tele- and servo-mechanisms, especially for remote control machinery, e.g., inspection robots or micromanipulators controlled by operators in a follow-up system.     

An Observation Method for Analyzing Operators’ Routine Activity in Computerized Control Rooms

An activity analysis method was developed for studying the structure and dynamics of control room operators’ activity during normal operation based on directly observable elements of the operators’ behavior. The method assesses current activity along three dimensions in each 5-min period of the shift. Intensity characterizes arousal level, direction shows whether the activity is directed predominantly at the process control task, at something else, or miscellaneous. Motivation reflects if the activity is driven by intrinsic or extrinsic motivation. A case study is presented, in which 3 morning, 3 afternoon, and 3 night shifts of a Nuclear Power Plant operator crew are involved. The obtained results gave a deeper understanding of the operators’ activity and also revealed an “arousal compensation” tendency.     

Force-Velocity Characteristics of Individual Human Skeletal Muscles: TBCIat and TBCIong. Outline of the Method

The aim of the work is to outline a procedure of finding force-velocity (F–V) characteristics (F = f(V)) of individual skeletal muscles of the human locomotor system. The presentation is based on an example concerning extensors of the elbow joint: the lateral and long heads of triceps brachii (TBCIat and TBCIong). The experimental part of the procedure involves a natural movement of using the upper extremity to push an external object of variable, adjustable load, engaging both the elbow and shoulder joint.

Five men aged 23 took part in the experiment. Their task was to push the handle of a physical pendulum whose moment of inertia could be adjusted within the range of 58 kg m²-450 kg m², so as to give it maximum angular velocity. During each trial the movement of the trunk, of the upper extremity and of the pendulum was video recorded and the force applied with the hand to the handle of the pendulum was measured.

In order to find the F–V characteristics a simulation model SHOULDER was used, which is capable of solving the synergy problem for muscles of the arm and the shoulder girdle.

It was found that despite considerable dispersion of experimental points the respective regression lines revealed a clear tendency of decreasing muscle force for increased shortening velocity of the monoarticular head (TBCIat) and of increasing muscle force for increased lengthening velocity of the biarticular head (TBCIong) of the triceps brachii muscle.     

Analysis of underlying causes of investigated loss of containment incidents in Dutch Seveso plants using the Storybuilder method

In the Netherlands there are around 400 “Seveso” sites that fall under the Dutch Major Hazards Decree (BRZO) 1999. Between 2006 and 2010 the Dutch Labour Inspectorate's Directorate for Major Hazard Control completed investigations of 118 loss of containment incidents involving hazardous substances from this group. On the basis of investigation reports the incidents were entered in a tailor-made tool called Storybuilder developed for the Dutch Ministry of Social Affairs and Employment for identifying the dominant patterns of technical safety barrier failures, barrier task failures and underlying management causes associated with the resulting loss of control events. The model is a bow-tie structure with six lines of defence, three on either side of the central loss of containment event. In the first line of defence, failures in the safety barriers leading to loss of control events were primarily equipment condition failures, pre start-up and safeguarding failures and process deviations such as pressure and flow failures. These deviations, which should have been recovered while still within the safe envelope of operation, were missed primarily because of inadequate indication signals that the deviations have occurred. Through failures of subsequent lines of defence they are developing into serious incidents. Overall, task failures are principally failures to provide adequate technical safety barriers and failures to operate provided barriers appropriately. Underlying management delivery failures were mainly found in equipment specifications and provisions, procedures and competence. The competence delivery system is especially important for identifying equipment condition, equipment isolation for maintenance, pre-start-up status and process deviations. Human errors associated with operating barriers were identified in fifty per cent of cases, were mostly mistakes and feature primarily in failure to prevent deviations and subsequently recover them. Loss of control associated with loss of containment was primarily due to the containment being bypassed (72% of incidents) and less to material strength failures (28%). Transfer pipework, connections in process plant and relief valves are the most frequent release points and the dominant release material is extremely flammable. It is concluded that the analysis of a large number of incidents in Storybuilder can support the quantification of underlying causes and provide evidence of where the weak points exist in major hazard control in the prevention of major accidents.     

米淀粉及其副产品清洁生产绩效评价研究

本文研究了传统米淀粉生产工艺物质流失及其生产过程控制与管理的内容,评价了米淀粉产品技改前与技改后的经济绩效和环境绩效.结果表明,开展清洁生产绩效评价研究,对于优化产品结构、实施工艺技术改造、提高资源能源利用率与节能减排效果具有重要意义.     

输变电工程在不同阶段的水土流失防治责任范围变化分析——以四川省500kV输变电工程为例

通过对四川省6个500kV输变电工程的水土保持设施验收技术评估工作,分析比较了上述工程水土流失防治责任范围在水土保持方案报告书（可研）阶段、工程建设期以及运行期的变化情况,结果表明建设期水土流失防治责任范围面积占水土保持方案报告书的50％～70％,运行期水土流失防治责任范围面积占建设期的30％～50％。