Managing rice pests with less chemicals

Losses caused by pests remain an important constraint to achieving high rice yields. Potentials of protecting these losses have stimulated innovations in pesticide development. Today the rice pesticide market is valued at US $ 3.0 billion per year. With reducing land available for rice production and increasing demand for food production, attention is turning towards intensification through higher fertilizer inputs and cropping. Such intensifications may in turn increase pest intensities and demand for more pesticides.A large proportion of insecticide sprays administered by rice farmers in Asia is influenced by misperceptions and overestimations of damages. Most farmers apply their first sprays in the first 40 days after crop establishment to control leaf feeding insects. However, these pests do not occur in sufficiently high densities to cause yield loss. Instead, such early season sprays may contribute towards development of secondary pests, such as the brown planthopper. Strategies to reduce insecticide use need to focus on enhancing naturally occurring biological control and understanding farmers' decision making behavior.Most fungicides used in rice are in the sub-tropical countries, like Japan, Korea, Taiwan and Vietnam. An important strategy towards reduction in fungicide use is through host plant resistance and gene deployment strategies. With biotechnology, tools may be used to characterize population structures in order to enhance these strategies. Cultural practices, such as rotations, cultivar mixtures, crop mosaics and planting times are being investigated.As cost of labor increases, farmers are likely to resort to using herbicides. The best way to accomplish weed control is the simultanous application of a variety of practices. These will include cultural, mechanical and chemical methods. The potentials of using naturally occurring enemies, such as plant pathogens, and the use of allelopathy are also being explored.     

山西地区的震源机制解结果

选用山西地区丰富的地震资料,利用单台小震综合断面解、4级以上地震的P波初动解、多台小震综合断面解的结果,叙述了山西地区震源机制结果的特点.得出山西地区震源机制结果有一定的复杂性,小震综合断面解的结果与华北地区的震源机制结果相似,单个地震的震源机制结果一致性较差的结论.     

山西地区的地壳应力场

根据近20年山西地区的震源机制结果,得出了山西地壳应力场存在着有别于华北应力场的局部小区域应力场,这种小区域应力场在中部断陷盆地都是以北西—北北西向的水平拉张作用为主,而在东、西两侧隆起区则是以水平挤压作用为主的结论.但如果把上述断层面解中的所有P轴、T轴再分别投影到吴尔夫网上,得到是一个一致性很好的断层面解,由此推断山西地区的平均应力场的主要特征与华北应力场的基本特征完全相同,而山西局部小区域应力场的特征随之消失.     

东营凹陷南坡近地表化探研究

利用引进的近地表化探系统,在济阳拗陷东营凹陷南坡的草桥油田进行了化探资料的采集、分析、处理及解释。研究证明:该系统在资料采集和现场质量控制方面有着明显的技术优势,在己知油田的断层、油水边界和油层尖灭线都有明显的地化异常。通过各种方法实验,对烃类在纵向上、横向上的丰度变化进行了初步探索。     

青藏高原物质东流的岩石层力学背景探讨

利用地表大地热流观测资料、岩石生热率及热导率数据研究了三江和四川盆地 6个地区的岩石层平均温度结构及强度分布。结果表明 ,整个三江地区岩石层温度较高 ,而四川盆地温度较低 ;在岩石层强度分布上 ,四川盆地为高强度区 ,而三江地区则为低强度区 ;整个三江地区构成了一条青藏高原物质东流的低强度通道 ;由于四川盆地高强度块体的阻挡 ,青藏高原向东的物质流在此转向近南向 ,沿三江地区流逸 ;不同岩石层块体的强度差异可能是控制高原物质流动态势的重要力学背景之一。     

移动式测绘系统（MMS）的发展与应用

移动式测绘系统（MMS）已在交通管理、城市规划、地图更新、工程勘测、精准农业、战场测绘等领域广泛应用。本文在简要叙述MMS基本概念和主要功能的基础上，探讨了MMS的发展现状和应用方向，进而提出了当前发展MMS需要解决的关键技术，仅供参考。     

Temporal-spatial variations of euphotic depth of typical lake regions in Lake Taihu and its ecological environmental significance

Euphotic depth can be defined as the portion of wa- ter column that supports the net primary productivity. Its lower end is the critical depth, namely, the depth measured when the daily net primary productivity is zero[1]. In the ecosystems of oceans, lakes and rivers, phytoplankton live in the euphotic depth and euphotic depth is usually taken as the lower boundary, when studying the primary productivity and biomass of phytoplankton; therefore the corresponding depth is sometimes called the t…     

黑龙江省含煤盆地分布与煤炭资源地质调查工作方向

在总结以往地质工作的基础上,对黑龙江省含煤盆地工作程度、区域地质概况、含煤地层等进行分析,认为黑龙江省主要成煤时代为中生代和新生代,受滨太平洋构造影响,构造形态为北北东向的三隆三坳,聚煤作用以断陷带内为主。以此将全省划分为6个主要聚煤带,97个含煤盆地,其中优先选择33个盆地,分为18个区块作为今后的调查方向,并提出相应的工作重点、原则、方法及主要工作量。     

A numerical study on 2-D compressive wave propagation in rock masses with a set of joints along the radial direction normal to the joints

An explosion in a borehole or an accidental explosion in a tunnel will generate a two-dimensional (2-D) compressive wave that travels through the surrounding rock mass. For the problem of 2-D compressive wave propagation in a rock mass with parallel joints in the radial direction normal to the joints, parametric studies on the transmission ratio and the maximum rebound ratio are performed in universal distinct element code. The variation of the transmission ratio with the ratio of joint spacing to wavelength is generalized into a characteristic curve, which can be used as a prediction model for estimating the transmission ratio. The relationship between the maximum rebound ratio and the influence factors is obtained in charts. The charts can be used as a prediction model for estimating the maximum rebound ratio. The proposed prediction models for estimating the transmission ratio and the maximum rebound ratio are applied to a field explosion test, Mandai test in Singapore. The minimum possible values of peak particle velocity (PPV) at the monitoring points are estimated by using the proposed prediction model for estimating the transmission ratio along the radial direction normal to the joints. On the other hand, the maximum possible values of PPV are estimated by using the proposed prediction model for estimating the maximum rebound ratio along the same radial direction. The comparison shows a good agreement between the field-recorded PPVs and the estimated range of PPVs given by the minimum possible PPVs and the maximum possible PPVs at the monitoring points in Mandai test. The good agreement between the estimated and field-recorded values validates the proposed prediction models for estimating peak particle velocity in a rock mass with a set of joints due to application of a compressive wave at the boundary of a tunnel or a borehole.     

辽东湾辽东带中南部古近纪古地貌恢复和演化及其对沉积体系的控制

采用井-震联合地层恢复法，对辽东湾辽东带中南部的古近纪进行了古地貌恢复。在此基础上拓宽了坡折带研究，将古地貌（包括古坡折带、古沟谷、古凸起等）纳入古物源供给系统的框架内探讨其对沉积体系的控制作用。分析表明：在构建完整物源供给系统的前提下，古地貌诸单元及其组合样式对沉积体系有着明显的控制作用。主要表现为：不同级次的物源体系导致沉积体类型和规模存在差异；物源区沟谷的分布及其赋存时期制约着砂体的主要分布位置、时期及规模；坡折带样式决定砂体的类型、规模及分布；古地貌组合样式控制储集体的成因、富集位置和规模大小。因此，古地貌分析对储层的预测和识别具有明显的指导作用。勘探实践证明，将其与常规储层预测方法联用，能够很大程度地提高储层预测的精度。