Search results for "stability index"
showing 9 items of 9 documents
Persistent Employment Instability and Fertility Intentions: The Gender-Specific Effect within Couples in Italy
2014
Our paper adds to the growing literature on the measurement of employment instability and on that on its consequences on fertility dynamics. We argue that many of these studies disregard a crucial dimension of employment instability: its persistence (duration). It is the persistence in an unstable condition, more than the status itself, that may have the most severe consequences on subsequent family choices. In this paper, we propose an index of persistence in employment instability that synthesizes all the information inside the individual sequence of employment statuses in a single number accounting simultaneously for the duration, sequencing, intensity, and labour market circumstances. T…
Reassessment of voltage stability for distribution networks in presence of DG
2016
There is a growing interest in integrating renewable energy based distributed generation (DG) in the electrical power distribution networks. The installation of DG units at distribution level impacts critically the planning and operation characteristics of the network. The type, location, number and capacity of the integrated DGs affects system behavior and performance. In this paper the effect of installing new DGs on the distribution network voltage stability is studied. The optimal location of the newly installed DGs are decided based on the Power Stability Index (PSI) and Voltage Stability Index (VSI). Moreover, Voltage Stability Margin (VSM) of the interconnected DG distribution networ…
New Indices Determining Heavy Metals Migration in a Sewage Sludge
2015
Abstract The four step procedure developed by the European Community Bureau of Reference (BCR) is the optimum means of identifying heavy metal fractions in sewage sludge samples. Using the BCR procedure enables to get the date basing on which one can calculate metal stability index which supplies information on the strength of metal bonds with mineral organic soil components. Unfortunately, very popular formulae describing this index do not possess any theoretical justification and do not generate all values in the range of [0; 1]. Hence, in this paper one has presented new formulae describing not only the stability index but also a strictly connected with it the mobility index. In addition…
Load modelling influence on voltage stability assessment in distribution systems. Part II: Extension to a complex radial system and applications
2006
The single-line equivalent model is commonly used for voltage stability studies in both distribution and transmission systems. Referring to a single-line system, in the companion paper [1] the authors presented the theoretical aspects of voltage stability related to the load characteristics. In particular, expressions of the stability index for constant power, constant impedance and constant current loads, singularly and in all the possible combinations have been obtained. This index indicates how far the load node is from its voltage collapse point, allowing the maximum load power beyond which voltage collapse takes place to be evaluated. In this paper a simple method to evaluate the param…
Load modelling influence on voltage stability assessment in distribution systems. Part I: Stability index and critical power for a single-line system
2006
The single-line equivalent model is commonly used for voltage stability studies in both distribution and transmission systems. Referring to a single-line system, in the companion paper [1] the authors presented the theoretical aspects of voltage stability related to the load characteristics. In particular, expressions of the stability index for constant power, constant impedance and constant current loads, singularly and in all the possible combinations have been obtained. This index indicates how far the load node is from its voltage collapse point, allowing the maximum load power beyond which voltage collapse takes place to be evaluated. In this paper a simple method to evaluate the param…
An improved method for determining voltage collapse proximity of radial distribution networks
2005
The two-bus equivalent model is commonly used for voltage stability studies in both distribution and transmission systems. The paper presents a simple method to evaluate, for each bus, the parameters which define the equivalent circuit of a radial distribution network. In particular, a straightforward way for determining the Thévenin equivalent impedance behind a load node is proposed, which allows to better identify the maximum loading point beyond which the voltage collapse takes place in the network. Simulation results show that the proposed method is significantly more accurate than other existing methods on evaluating the critical power at a particular node (i.e. the weak node of the n…
Persistent Employment Instability and Fertility Intentions in Italy
2014
Our paper adds to the growing literature on the measurement of employment instability and on that on its consequences on fertility dynamics. We argue that many of these studies disregard a crucial dimension of employment instability: its persistence (duration). It is the persistence in an unstable condition, more than the status itself, that may have the most severe consequences on subsequent family choices. In this paper, we propose an index of persistence in employment instability that synthesizes all the information inside the individual sequence of employment statuses in a single number accounting simultaneously for the duration, sequencing, intensity, and labour market circumstances. T…
Soil Physical Quality of Citrus Orchards Under Tillage, Herbicide, and Organic Managements
2018
Abstract Soil capacity to support life and to produce economic goods and services is strongly linked to the maintenance of good soil physical quality (SPQ). In this study, the SPQ of citrus orchards was assessed under three different soil managements, namely no-tillage using herbicides, tillage under chemical farming, and no-tillage under organic farming. Commonly used indicators, such as soil bulk density, organic carbon content, and structural stability index, were considered in conjunction with capacitive indicators estimated by the Beerkan estimation of soil transfer parameter (BEST) method. The measurements taken at the L'Alcoleja Experimental Station in Spain yielded optimal values fo…
Application of the PHREEQC Program to Assess the Chemical Stability of Tap Water in Kielce
2020
Badania przeprowadzono na próbkach wody w Kielcach pochodzące z dwóch ujęć: Białogon i Zagnańsk. Przedstawiono wyniki wybranych wskaźników dla tych wód, m.in. najważniejszych wpływających na ich stabilność chemiczną, tj. wapnia lub magnezu. Następnie, za pomocą programu PHREEQC, obliczono wskaźniki stabilności dla wód w Kielcach z dwóch ujęć, o których mowa. W kolejnym etapie sprawdzono poprawność metody badania wody za pomocą programu poprzez bilans jonowy wody i porównanie pH wyznaczonej wody z wartością wyznaczoną w wyniku obliczeń. Dla wyżej wymienionych czynności przygotowano tabele i obliczenia, na podstawie których wyciągnięto odpowiednie wnioski