Gully control: Determining treatment priorities for gullies in a network

This report is about a newly developed procedure for setting priorities in gully control. It explains basic gully systems and developments as influenced by geomorphologic processes on which the proposed procedure is based. These processes consist of two types: one, representing interactions between the individual gullies of a network; the other, mechanisms initiated within a given gully by localized instability conditions. Classifying gullies into continuous and discontinuous types not only allows determination of network types but also points to critical locations that must be considered by the designer.The procedure for analyzing gully networks to establish treatment priorities consists of five steps as follows: 1) determining type of network based on gully types; 2) stream ordering of the network gullies; 3) tallying tributaries of each gully; 4) analyzing stage of development of each gully; 5) ranking of treatment priorities.Situations may exist—remote location and negligent downstream effects—where gully control is not desirable and the land manager decides to let nature take its course and to await the establishment of a new stream equilibrium condition before the watershed resources will be intensively utilized. Also political or funding aspects may not permit gully control efforts. Such aspects as well as types of individual treatment measures are beyond the scope of this report. The proposed technique establishes priorities that depend on opportunities to exert greatest control for least cost and to prevent the greatest amount of future erosion.     

The Contribution of Headwater Streams to Biodiversity in River Networks1

Abstract: The diversity of life in headwater streams (intermittent, first and second order) contributes to the biodiversity of a river system and its riparian network. Small streams differ widely in physical, chemical, and biotic attributes, thus providing habitats for a range of unique species. Headwater species include permanent residents as well as migrants that travel to headwaters at particular seasons or life stages. Movement by migrants links headwaters with downstream and terrestrial ecosystems, as do exports such as emerging and drifting insects. We review the diversity of taxa dependent on headwaters. Exemplifying this diversity are three unmapped headwaters that support over 290 taxa. Even intermittent streams may support rich and distinctive biological communities, in part because of the predictability of dry periods. The influence of headwaters on downstream systems emerges from their attributes that meet unique habitat requirements of residents and migrants by: offering a refuge from temperature and flow extremes, competitors, predators, and introduced species; serving as a source of colonists; providing spawning sites and rearing areas; being a rich source of food; and creating migration corridors throughout the landscape. Degradation and loss of headwaters and their connectivity to ecosystems downstream threaten the biological integrity of entire river networks.     

住宅小区室外楼前管网排布位置探讨

随着现代住宅区室外生活设施和配套项目的增多,配套管线相互交叉、相互干扰施工的现象愈来愈突出.根据施工经验采用科学合理的楼前管网排布顺序和施工顺序将会给施工带来安全和快捷.     

赣江流域系统特征与工业开发模式

依据赣江流域的系统特征,选择工业开发模式,是地域经济发展的战略核心问题。推进资源有效利用与高度利用,优势产品开发与替代产品开发,实现经济发展趋于由下游而上游的资源型—加工型—技术型产业结构指向的有序转化,资源开发与国土冶理趋于由上游而下游的生态经济良性循环,为赣江流域工业开发模式的基本要点。     

蒙脱石b轴有序度的测定及其实用意义

粉末X射线衍射测量蒙脱石结构有序度,采用v/p值法仅反映c轴方向有序度,不能代表a、b轴方向有序度。作者提出(02)反射带峰形不对称程度是b轴有序程度的直观反映,将该峰峰高(H)与2/3高宽(W)的比值定义为蒙脱石晶体结构的b轴有序度,H/W值越大,b轴有序度越高,反之,朽序度低。H/W值对蒙脱石原矿评价与应用研究有一定意义。     

灰色关联分析在玉米高产施肥技术上的应用

通过施肥因子对玉米产量的分析，研究影响作物产量的各施肥因子的影响程度．通过关联因子和关联序分析，提出一套切实可行的施肥方案．并为今后研究作物施肥提供一条新的行之有效的研究途径和一种新的方法．研究结果表明：在玉米高产施肥中，施肥与产量之间的关联序为：基N＞追N＞总N＞总K＞追K＞基P＞追P＞总P（总N＞总K＞总P），粒N＞苗N＞穗N＞穗K＞粒P＞苗K＞苗P＞穗P＞粒K．这为玉米高产施肥提供了重要的理论依据，并为作物施肥技术研究开辟了一条新路．     

Multiple indicators, partially ordered sets, and linear extensions: Multi-criterion ranking and prioritization

This paper is concerned with the question of ranking a finite collection of objects when a suite of indicator values is available for each member of the collection. The objects can be represented as a cloud of points in indicator space, but the different indicators (coordinate axes) typically convey different comparative messages and there is no unique way to rank the objects while taking all indicators into account. A conventional solution is to assign a composite numerical score to each object by combining the indicator information in some fashion. Consciously or otherwise, every such composite involves judgments (often arbitrary or controversial) about tradeoffs or substitutability among indicators. Rather than trying to combine indicators, we take the view that the relative positions in indicator space determine only a partial ordering and that a given pair of objects may not be inherently comparable. Working with Hasse diagrams of the partial order, we study the collection of all rankings that are compatible with the partial order (linear extensions). In this way, an interval of possible ranks is assigned to each object. The intervals can be very wide, however. Noting that ranks near the ends of each interval are usually infrequent under linear extensions, a probability distribution is obtained over the interval of possible ranks. This distribution, called the rank-frequency distribution, turns out to be unimodal (in fact, log-concave) and represents the degree of ambiguity involved in attempting to assign a rank to the corresponding object. Stochastic ordering of probability distributions imposes a partial order on the collection of rank-frequency distributions. This collection of distributions is in one-to-one correspondence with the original collection of objects and the induced ordering on these objects is called the cumulative rank-frequency (CRF) ordering; it extends the original partial order. Although the CRF ordering need not be linear, it can be iterated to yield a fixed point of the CRF operator. We hypothesize that the fixed points of the CRF operator are exactly the linear orderings. The CRF operator treats each linear extension as an equal voter in determining the CRF ranking. It is possible to generalize to a weighted CRF operator by giving linear extensions differential weights either on mathematical grounds (e.g., number of jumps) or empirical grounds (e.g., indicator concordance). Explicit enumeration of all possible linear extensions is computationally impractical unless the number of objects is quite small. In such cases, the rank-frequencies can be estimated using discrete Markov chain Monte Carlo (MCMC) methods.     

CHEMICAL PRECIPITATION-COAGULATION FOR ORGANIC COLOR REMOVAL FROM GOUNDWATERS1

ABSTRACT: Many wells produce water that is highly colored by organic substances. Colored water may cause aesthetic, economic, and health problems for the cities using it as a municipal supply. Characterization of water from a number of wells showed that the color causing compounds were hydroxylated aromatic carboxylic acids which were precipitated below pH 4.5 and were almost completely ionized above pH 4.5. Through jar tests, a chemical precipitation-coagulation treatment system was developed. The optimal sequence of chemical addition was alum first, followed by pH adjustment and addition of a polyelectrolyte. Rapid mix tests demonstrated the need for a reaction period after alum and after acid addition, and that the rapid mix time controlled floc size for a given flocculation period. Flocculation tests, varying both the floc time and mean velocity gradient, G, showed that an optimum G exists for each floc time and that the residual color decreased with decreasing values of velocity gradient.     

Different ranking methods: potentialities and pitfalls for the case of European opinion poll

Prioritization and ranking of objects are primary needs in various substantive fields. It might be said that ranking and comparison are the first step in every risk assessment procedure, whatever the ‘risk’ is intended as: social, environmental, political or economic. Often objects to be ranked are valued by a multi-dimensional attribute which is usually transformed into a composite numerical score. In spite of conventional solutions, the author agrees with recent recommendations of performing multiple ranking, keeping indicators separated. Different innovative methods are analyzed and compared: Hasse diagrams method, POSAC and Nonlinear PCA. The first one stems directly from partial order theory, the second one may be seen as an approximation of Hasse representation in a two dimensional space, whilst the third one belongs to the wide set of non-linear multivariate techniques and it is particularly suitable in handling data of categorical type. Among them, the first two methods compare objects on the basis only on order property of data, whilst the last one simultaneously performs an optimal scale of qualitative attributes and a ranking of objects. The case study is based on the Eurobarometer survey carried out in 2002, at the request of the European Commission, which collects Europeans opinion about various political and social issues. The analysis is focused on users’ level of satisfaction about access easiness, cost, quality, information received and contracts of various services of general interest, such as telephone services, power (gas and electricity) providers, water and postal utilities, urban and rail transports. Separate indicators are set up for each facet of each service within different European regions. Eventually, the ranking of European regions is performed on the basis of the overall performance of services of general interest, as perceived by users. Selected methods lead to almost alike results, still with some differentiations due to different approaches used. As it frequently occurs, each method has its own advantages and pitfalls which are here explored and compared.     

超声协同Fe0@Fe3O4降解四氯化碳

采用附着在Fe_3O_4纳米颗粒上的纳米零价铁(n ZVI)对四氯化碳(CCl4)还原脱氯.同时,利用SEM和BET等技术对Fe~0@Fe_3O_4的表面形貌和粒径进行表征,探究了不同反应条件如Fe~0@Fe_3O_4投加量、超声功率、初始pH值、温度和CCl4初始浓度对CCl4去除率的影响.最后,比较了Fe~0@Fe_3O_4、n ZVI和Fe_3O_4颗粒对CCl4的去除效果.结果表明,Fe~0@Fe_3O_4比n ZVI比表面积更大、分散性更好.超声功率和温度的提高对CCl4的降解有明显的促进作用.在最佳条件(催化剂投加量0.5 g·L-1,超声功率300 W,初始pH=7.0,温度30℃,CCl4初始浓度2 mg·L-1)下,Fe~0@Fe_3O_4复合材料在60 min内对CCl4的去除效率为88.5%,明显高于n ZVI(60.9%)和Fe_3O_4颗粒(13.2%).Fe~0@Fe_3O_4对CCl4去除过程符合伪一级动力学模型.