A general geomorphological recession flow model for river basins

Recession flows in a basin are controlled by the temporal evolution of its active drainage network (ADN). The geomorphological recession flow model (GRFM) assumes that both the rate of flow generation per unit ADN length (q) and the speed at which ADN heads move downstream (c) remain constant during a recession event. Thereby, it connects the power law exponent of -dQ/dt versus Q (discharge at the outlet at time t) curve, , with the structure of the drainage network, a fixed entity. In this study, we first reformulate the GRFM for Horton-Strahler networks and show that the geomorphic ((g)) is equal to D/(D-1), where D is the fractal dimension of the drainage network. We then propose a more general recession flow model by expressing both q and c as functions of Horton-Strahler stream order. We show that it is possible to have = (g) for a recession event even when q and c do not remain constant. The modified GRFM suggests that is controlled by the spatial distribution of subsurface storage within the basin. By analyzing streamflow data from 39 U.S. Geological Survey basins, we show that is having a power law relationship with recession curve peak, which indicates that the spatial distribution of subsurface storage varies across recession events. Key Points The GRFM is reformulated for Horton-Strahler networks. The GRFM is modified by allowing its parameters to vary along streams. Sub-surface storage distribution controls recession flow characteristics.

A Simple Hysteretic Energy Harvesting Method for Nonneutral AC Switches in Load Automation

This paper presents a simple hysteretic method to obtain the energy required to operate the gate-drive, sensors, and other circuits within nonneutral ac switches intended for use in load automated buildings. The proposed method features a switch-mode low part-count self-powered MOSFET ac switch that achieves efficiency and load current THD figures comparable to those of an externally gate-driven switch built using similar MOSFETS. The fundamental operation of the method is explained in detail, followed by the modifications required for practical implementation. Certain design rules that allow the method to accommodate a wide range of single-phase loads from 10 VA to 1 kVA are discussed, along with an efficiency enhancement feature based on inherent MOSFET characteristics. The limitations and side effects of the method are also mentioned according to their levels of severity. Finally, experimental results obtained using a prototype sensor switch are presented, along with a performance comparison of the prototype with an externally gate-driven MOSFET switch.

Internal resonance of an L-shaped beam with a limit stop .1. Free vibration

Real-life structures often possess piecewise stiffness because of clearances or interference between subassemblies. Such an aspect can alter a system's fundamental free vibration response and leads to complex mode interaction. The free vibration behaviour of an L-shaped beam with a limit stop is analyzed by using the frequency response function and the incremental harmonic balance method. The presence of multiple internal resonances, which involve interactions among the first five modes and are extremely complex, have been discovered by including higher harmonics in the analysis. The results show that mode interaction may occur if the higher harmonics of a vibration mode are close to the natural frequency of a higher mode. The conditions for the existence of internal resonance are explored, and it is shown that a prerequisite is the presence of bifurcation points in the form of intersecting backbone curves. A method to compute such intersections by using only one harmonic in the free vibration solution is proposed. (C) 1996 Academic Press Limited

Selective plankton feeding by the coregonid ”bondella” (Coregonus sp.) of Lake Maggiore [Translation from: Translation from: Memorie dell'Istituto Italiano di Idrobiologia Dott.Marco de Marchi 31 181-203, 1974]

In recent times, some specialists have begun to study the subject of food selection of fish in an organized way, thus highlighting its importance. In the present work, the author intends to evaluate the impact of predation on the eupelagic zooplanktonic biocenosis of Lake Maggiore, producing, in this way, as far as possible, a basis for a better understanding of the population dynamics of the species of zooplankton directly involved. Another aspect which has been studied is that related to the mechanism of selective capture set in action by the predator. To this end the study tries to bear in mind that the subject should be interpreted as a function of numerous factors acting contemporaneously, that is as the interaction of characters peculiar to the predator and to the prey. The species studied, locally called ”bondella”, belongs to the family Salmonidae, subfamily Coregoninae and was introduced into Lake Maggiore in 1950.

凤眼莲、水花生若干光合作用参数与酶类的研究

在正常的生长条件下，凤眼莲有较高的叶面系数、叶绿素含量和光合强度。叶片可溶性糖含量也高。在低温胁迫下，凤眼莲和水花生根系活力和过氧化物酶、过氧化氢酶、细胞色素氧化酶、淀粉酶等酶活性均明显下降。试验结果表明，凤眼莲对低温胁迫较水花生更为敏感。

Algebra Llinol - Cyflwyniad

Cyfieithiad yw'r llyfr hwn o Linear Algebra - An Introduction a ymddangosodd gyntaf yn 1978 ac a gyhoeddwyd gan y cwmni Van Nostrand Reinhold. Cafwyd Ail Argraffiad yn 1982 a dros y blynyddoedd bu nifer o ail brintiadau. Yn y cyfamser cyfieithwyd y llyfr i'r Groeg a Thwrceg. Er i'r llyfr gael ei ddefnyddio dros y blynyddoedd gan nifer o fyfyrwyr yn Aberystwyth a oedd yn cyflwyno eu gwaith yn Gymraeg, nid oedd ar gael yn y Gymraeg. Dyma, o'r diwedd, ymgais i wneud rhyw fath o iawn am hynny. Er bod y llyfr wedi bod allan o brint yn y Saesneg ers rhai blynyddoedd yn awr, mae'n amlwg ei fod yn dal i gael ei gymeradwyo mewn nifer o brifysgolion. Felly, y gobaith yw y bydd o ddefnydd. Efallai mai'r peth nesaf bydd ei gyfiethu'n ?l i'r Saesneg! Mae nifer o newidiadau yn y fersiwn hwn. Mae'n siwr bod nifer o gamgymeriadau ac efallai gwelliannau posibl i'r cyfieithu - byddwn yn ddiolchgar dderbyn unrhyw awgrymiadau. Gellir eu cyflwyno hefyd drwy Dr Gwion Evans o'r Adran Fathemateg, Prifysgol Aberystwyth.

The Right to Self-Defence in National and International Law: The Role of the Imminence Requirement

This article explores the doctrine of self-defence within the context of the challenges directed at the imminence requirement, from the perspective of both national and international law. The article will attempt to illustrate that the requirement of imminence underlines the political character of the self-defence doctrine wherein private force may only be resorted to in the absence of institutional protection. This study will argue that the imminence rule can not merely be regarded as a "proxy" for establishing necessity; rather, the elements of imminence, necessity, and proportionality are inextricably connected to ensure that defensive force is only resorted to when national or international authorities are not in a position to prevent an illegal aggression, and that the defensive lethal force is not abused.