The influence of dispersible clay and wetting/drying cycles on the tensile strength of a red-brown earth

Soil Research ◽  
1992 ◽  
Vol 30 (3) ◽  
pp. 297 ◽  
Author(s):  
BD Kay ◽  
AR Dexter

The tensile strength of aggregates is a dynamic property under field conditions and for any given soil reflects the integration of processes leading to a strengthening and weakening of failure zones. The objectives of this study were to determine if variation in the tensile strength of natural aggregates from a red-brown earth could be related to the combined effects of (a) conditions favouring dispersion of clay and a subsequent increase in strength by cementation on drying and (b) wetting/drying cycles which would result in a decrease in strength. Aggregates were collected from the A horizon of different long-term rotations. The seasonal variation in tensile strength was assessed using data collected in 1988 and unpublished data which had been collected annually between 1978 and 1981. Trends in tensile strength over 5 years confirmed the importance of an interaction between climatic conditions which could lead to increased dispersion of clay and wetting/drying cycles. The extent of weakening of failure zones by wetting/drying cycles varied with the rotation. The nature of the impact of cropping history on tensile strength was dependent on antecedent climatic conditions.

2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2845-2855
Author(s):  
Stanimir Zivanovic ◽  
Ivana Tosic

The Djerdap National Park in Serbia is vulnerable to fires. The variability of a fire in the Djerdap National Park is studied depending on the impact of climatic conditions. The influence was investigated on a yearly, monthly, and daily basis using data recorded at the meteorological station Veliko Gradiste. Data were analyzed for two periods: 1961-1990 and 1991-2017, and for the year of 2011. Special attention is devoted to the conditions for the emergence of the largest forest fire in the Djerdap National Park in September 2011. In this study, the Angstrom index, the Nesterov index, and method of deficit and surplus of precipitation are used to predict the risk of fire. There was an increased danger of fire in the forests in the period of 1991-2017 compared to the period of 1961-1990. Indices showing fire risk are increased for the months of June, July, and August. The September 2011 is characterized by an increase of average monthly air temperature by 3.7?C and a reduction of the total monthly rainfall of 32.3 mm compared to a long-term average value which favorable influenced to the occurrence of large forest fires.


2019 ◽  
Vol 10 (04) ◽  
pp. 1950013
Author(s):  
CRISTINA CATTANEO ◽  
EMANUELE MASSETTI

This paper analyzes whether migration is an adaptation strategy that households employ to cope with climate in Nigeria. We estimate our model using the cross-sectional variation in climate and long-term migration decisions because we are interested in the average response to long-term climatic conditions. For households that operate farms, we find that the relationship between climate and migration is nonlinear. In particular, climates closer to ideal farming conditions are associated with a higher propensity to migrate, whereas in the least favorable climatic conditions, the propensity to migrate declines. The marginal effect of rainfall and temperature changes on migration varies by season. We estimate the impact of climate change on the number of migrant households in 2031–2060 and 2071–2100, ceteris paribus. With current population levels, climate change generates between 3.6 and 6.3 million additional migrants, most of them being internal. However, these estimates are not statistically significant.


Computers ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 35
Author(s):  
Gilberto Ayala-Bastidas ◽  
Hector G. Ceballos ◽  
Francisco J. Cantu-Ortiz

The impact of the strategies that researchers follow to publish or produce scientific content can have a long-term impact. Identifying which strategies are most influential in the future has been attracting increasing attention in the literature. In this study, we present a systematic review of recommendations of long-term strategies in research analytics and their implementation methodologies. The objective is to present an overview from 2002 to 2018 on the development of this topic, including trends, and addressed contexts. The central objective is to identify data-oriented approaches to learn long-term research strategies, especially in process mining. We followed a protocol for systematic reviews for the engineering area in a structured and respectful manner. The results show the need for studies that generate more specific recommendations based on data mining. This outcome leaves open research opportunities from two particular perspectives—applying methodologies involving process mining for the context of research analytics and the feasibility study on long-term strategies using data science techniques.


2016 ◽  
Vol 23 (6) ◽  
pp. 1343-1352 ◽  
Author(s):  
Marion Karl ◽  
Gordon Winder ◽  
Alexander Bauer

While the relation between terrorism and tourism has been an important topic for tourism research, the questions whether terrorism affects tourism immediately and how long after a terrorism event tourism recovers are, as yet, not clearly answered. The aim of this article is to better understand the magnitude and temporal scale of the impact of terrorism on tourism. To this end, a research model differentiating between short-term and long-term effects of terrorism on tourism is developed and analyzed for the destination Israel using data on tourists from Germany. The results show both short-term and long-term impacts with a time lag between the terrorist event and the beginning of tourism decline of 1 or up to 6 months. An economic influence on the development of tourist arrivals was not detected, but seasonality plays an important role in the relationship between terrorism and tourism.


2020 ◽  
Vol 17 (2) ◽  
pp. 1-18
Author(s):  
Maja Ivanović-Đukić ◽  
Marija Petrović-Ranđelović ◽  
Miljana Talić

The paper investigates the impact of different factors on the establishment and development of social enterprises (SPs). The aim of this paper is to identify the key stimulants and restrictions of development of SPs in the Republic of Serbia, and to propose measures, the application of which can increase their long-term sustainability. The paper is based on exploratory research using data covering 27 interviews with founders of social enterprises in the Republic of Serbia. By applying the methods of regression analysis, it was found that favorable financial resources (especially grants) are the key stimulants for the establishment of social enterprises, while the enthusiasm of managers of social enterprises has the greatest impact on their development. It was found also that legal regulations and the macroeconomic environment, as well as difficulties in accessing the market, are serious restrictions on the establishment of social enterprises, while lack of knowledge in the field of marketing and management limit the development of social enterprises in the Republic of Serbia.


2021 ◽  
Vol 14(63) (2) ◽  
pp. 79-84
Author(s):  
Fitim Deari ◽  

The purpose of this study is to investigate the impact of the current Covid-19 pandemic on profitability ratios of large commercial banks in the Republic of North Macedonia. By using data over the period 2004 – 2020, ten profitability indicators are examined. These indicators are investigated by comparing their values before and during the Covid-19 pandemic. Overall, the study reveals a preliminary evidence that large commercial banks are affected by the Covid-19 pandemic. So far, profitability of large banks has not changed significantly due to Covid-19 and they keep satisfactory profitability levels. However, this impact should be investigated furthermore in next studies because the current pandemic has long-term effects.


Author(s):  
Nguyen Van Tan

This paper examines the impact of equitization on financial and operating performance of state-owned enterprises (SOEs) in Vietnam. Previous related privatization theories have not explained whether there is an improvement in financial and operating performance of equitized SOEs compared to non-equitized SOEs or not. This study proposes to use with-without comparison method through the average treatment effect measuring the impact of equitization on financial and operating performance of SOEs. By using data of 114 SOEs equitized in the period from 2012 to 2014, the author finds that equitized SOEs can not improve profitability, operating efficiency, and output when considering non-equitized SOEs. There is also no evidence for a reduction in the number of employees of equitized SOEs after equitization. These findings are in contrast to previous studies in Vietnam, but there are similarities with the results of studies in China. This is because equitized SOEs in the early post-equitization period in Vietnam are still monitored by the Vietnamese government, as well as the equitized enterprises in the period 2012-2014 are mainly large-scale ones with slow change of operating objectives, monitoring mechanism and weak competitiveness after equitization. However, equitization can help equitized SOEs operate more efficiently than non–equitized SOEs when considering non-listing status or industry group. This research provides implications for the Vietnamese government to encourage non-equitized enterprises to participate in the equitization program actively. The research results also help investors to have appropriate long-term investment strategies in equitized SOEs. This paper also has some limitations for further research.


Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2745 ◽  
Author(s):  
Fotiou ◽  
Vita ◽  
Capros

The paper presents a newly developed economic-engineering model of the buildings sector and its implementation for all the European Union (EU) Member States (MS), designed to study in detail ambitious energy efficiency strategies and policies, in the context of deep decarbonisation in the long term. The model has been used to support the impact assessment study that accompanied the European Commission’s communication “A Clear Planet for All”, in November 2018. The model covers all EU countries with a fine resolution of building types, and represents agent decision-making in a complex and dynamic economic-engineering mathematical framework. Emphasis is given to behaviours driving the energy renovation of buildings and the ensuing choice of equipment for heating and cooling. The model represents several market and non-market policies that can influence energy decisions in buildings and promote deep energy renovation. Moreover, the paper presents key applications for supporting policies targeting ambitious reduction of energy consumption and carbon emissions in buildings across Europe. The results illustrate that the achievement of ambitious energy-efficiency targets in the long-term heavily depends on pursuing a fast and extensive renovation of existing buildings, at annual rates between 1.21% and 1.77% for the residential sector and between 0.92% to 1.35% for the services sector. In both cases, the renovation rates are far higher past trends. Strong policies aimed at removing non-market barriers are deemed necessary. Electrification constitutes a reasonable choice for deeply renovated buildings and, as a result, almost 50% of households chooses electric heating over gas heating in the long term. However, heat pumps need to exploit further their learning potential to be economical and implementable for the various climatic conditions in Europe. The results also show that the cost impacts are modest even if renovation and decarbonisation in buildings develop ambitiously in the EU. The reduced energy bills due to energy savings can almost offset the increasing capital expenditures. Fundraising difficulties and the cost of capital are, however, of concern.


1992 ◽  
Vol 25 (11) ◽  
pp. 69-76 ◽  
Author(s):  
S. Li ◽  
J. Migita

A mathematical model is developed to predict the runoff of pesticides from paddy field to a river. The model describes the long term runoff as a function of physical-chemical properties of pesticides, cultural practices and climatic conditions. It is assumed that the adsorption and desorption of pesticides between soil and water phases are in equilibrium state, while the degradation in water and soil and the evaporation from water to atmosphere are of first-order reaction. The model is used to examine the relationships between the seasonal amounts of pesticide runoff and their environmental dynamic factors. A four-stage evaluation system is proposed to assess the impact of the runoff on drinking water by taking into account the amount of application, runoff ratio, toxicity and the possibility of being removed from raw water by water purification processes. The model simulates the daily variation of contaminant level in river water, thereby providing a basis for making recommendations for pesticide usage and water management for rice cultivation.


2011 ◽  
Vol 4 (3) ◽  
pp. 2525-2565 ◽  
Author(s):  
A. J. Mannucci ◽  
C. O. Ao ◽  
X. Pi ◽  
B. A. Iijima

Abstract. We study the impact of large-scale ionospheric structure on the accuracy of radio occultation (RO) retrievals of atmospheric parameters such as refractivity and temperature. We use a climatological model of the ionosphere as well as an ionospheric data assimilation model to compare quiet and geomagnetically disturbed conditions. The largest contributor to ionospheric bias is physical separation of the two GPS frequencies as the GPS signal traverses the ionosphere and atmosphere. We analyze this effect in detail using ray-tracing and a full geophysical retrieval system. During quiet conditions, our results are similar to previously published studies. The impact of a major ionospheric storm is analyzed using data from the 30 October 2003 "Halloween" superstorm period. The temperature retrieval bias under disturbed conditions varies from 1 K to 2 K between 20 and 32 km altitude, compared to 0.2–0.3 K during quiet conditions. These results suggest the need for ionospheric monitoring as part of an RO-based climate observation strategy. We find that even during quiet conditions, the magnitude of retrieval bias depends critically on ionospheric conditions, which may explain variations in previously published bias estimates that use a variety of assumptions regarding large scale ionospheric structure. We quantify the impact of spacecraft orbit altitude on the magnitude of bending angle error. Satellites in higher altitude orbits (≧700 km) tend to have lower biases due to the tendency of the residual bending to cancel between the top and bottomside ionosphere. We conclude with remarks on the implications of this study for long-term climate monitoring using RO.


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