scholarly journals The Impact of Long-Term Physical Salt Attack and Multicycle Temperature Gradient on the Mechanical Properties of Spun Concrete

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4811
Author(s):  
Romualdas Kliukas ◽  
Arūnas Jaras ◽  
Ona Lukoševičienė
Keyword(s):  
Mechanical Properties ◽  
Temperature Gradient ◽  
Ambient Conditions ◽  
Chemical Admixtures ◽  
Cyclic Temperature ◽  
Spun Concrete ◽  
Physical Salt Attack ◽  
The Impact ◽  
Positive Effect

The article is focused on spun concrete made with different chemical admixtures under long-term exposure to aggressive salt-saturated ground water and a cyclic temperature gradient. Over a long-term experimental investigation, 64 prismatic spun concrete specimens were subjected to multicycle (75–120) processing under combined aggressive ambient conditions. Prismatic specimens were soaked in water or saline and dried at a temperature of 45–50 °C. The long-term multi-cycle effect of the temperature gradient and physical salt attack on the compressive strength, Young’s modulus and durability of concrete was found to be negative. Chemical admixtures, though, improved the structure of spun concrete, thus having a significant positive effect on its physical-mechanical properties and durability.

scholarly journals The Reinforced Spun Concrete Poles under Physical Salt Attack and Temperature: A Case Study of the Effectiveness of Chemical Admixtures

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5111
Author(s):  
Romualdas Kliukas ◽  
Arūnas Jaras ◽  
Ona Lukoševičienė
Keyword(s):  
Transmission Lines ◽  
Environmental Conditions ◽  
Experimental Program ◽  
Initial Water ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Chemical Admixtures ◽  
Spun Concrete ◽  
Physical Salt Attack

The present paper focused on the investigation of the effectiveness of using various chemical admixtures and their effect on the strength and deformability of the reinforced spun concrete members—the supporting poles of the overhead power transmission lines—under the unfavorable long-term combined action of the aggressive salt-saturated groundwater and the temperature changes. According to the long-term experimental program, 96 prismatic spun concrete specimens were subjected to multi-cycle (25-50-75 cycles) processing under the combined aggressive environmental conditions. It has been found that chemical admixtures which decrease the initial water-cement ratio produce a considerable positive effect on the mechanical properties of spun concrete used in hot and arid climates and exposed to physical salt attack (PSA). Superplasticizers decrease the initial water-cement ratio the most, and, due to a unique concrete compaction method used, they produce the most homogeneous and dense concrete structure. They can be recommended as most effective in increasing the durability of spun concrete used under the above-mentioned aggressive environmental conditions.

scholarly journals The Demerger Impact upon Sustainable Development of Economic Entities: Evidence from Romania

2021 ◽  
Vol 13 (15) ◽  
pp. 8316
Author(s):  
Camelia Mirela Baba ◽  
Constantin Duguleană ◽  
Marius Sorin Dincă ◽  
Liliana Duguleană ◽  
Gheorghița Dincă
Keyword(s):  
Sustainable Development ◽  
Business Strategies ◽  
The Sustainable Development ◽  
Ex Post ◽  
Before And After ◽  
Almost All ◽  
The Impact ◽  
Profitability Ratios ◽  
Positive Effect

The Covid-19 induced economic crisis has significantly affected almost all businesses from nearly every sector, causing severe financial problems, lack of cash assets, and decrease of revenues. In this context, the economic entities were forced to look for adjustment and rescue solutions of their activities. One possible solution for the recovery and reorganization of economic entities’ activities is demerger. This paper evaluates the impact of demerger upon the sustainable development of economic entities in terms of economic efficiency and financial performances. To achieve this goal, a statistical analysis of profitability ratios before and after the demerger, as well as a structural analysis of 268 demerger projects for the April 2012–April 2021 period, were performed. The results attest there are no significant differences between the ex-ante and ex-post financial performances. However, demerger seems to have a positive effect upon analyzed companies helping them to overcome economic hardships, rethink their business strategies, and continue their activity in the medium and long-term time horizon.

scholarly journals Numerical Studies of the Effects of Water Capsules on Self-Healing Efficiency and Mechanical Properties in Cementitious Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Haoliang Huang ◽  
Guang Ye
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Cementitious Materials ◽  
Self Healing ◽  
Negative Effects ◽  
Numerical Studies ◽  
Healing Efficiency ◽  
The Impact ◽  
Positive Effect

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.

The Impact of Tariff Regulation on Investment in Russian Electricity Distribution Sector

2016 ◽  
Vol 2016 (5) ◽  
pp. 69-91
Author(s):  
Yuliya Orlova ◽  
Olga Kadreva
Keyword(s):  
District Heating ◽  
Distribution Networks ◽  
Investment Model ◽  
Electricity Distribution ◽  
Explanatory Factors ◽  
Dynamic Investment ◽  
Distribution Sector ◽  
The Impact ◽  
Positive Effect

The paper investigates the mid-term results of the tariff regulation influence on the amount of capital expenditures in Russian electricity distribution sector. We estimate panel data with the dynamic investment model using system GMM method. We showed that horizon of tariff regulation period is statistically significant and transition from the short-term regulation to the long-term tariff system had positive effect on the amount of regulated companies’ investments. At the same time we found that the design of long-term regulation applied in Russia in 2009–2013 (type of RAB-regulation and long-term indexation) was not statistically significant to the amount of investments. All over all, the amount of investments in electricity distribution networks has similar to European peers explanatory factors. The obtained results are important to the further improvement of regulation in power energy and can be applied in district heating as well.

The Influence of the Long-Term Storage of Hardwood on the Selected Physical and Mechanical Properties in View of Pulping

2016 ◽  
Vol 688 ◽  
pp. 10-16
Author(s):  
Blažej Seman ◽  
Anton Geffert ◽  
Jarmila Geffertova
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Continuous Production ◽  
Beech Wood ◽  
Physical And Mechanical Properties ◽  
Long Term Storage ◽  
The Impact ◽  
Term Storage ◽  
Strength In Bending

Wood is loosely stored to ensure continuous production inside paper mills where it is exposed to the effect of external factors. The impact of storage leads to some changes of mechanical and physical properties of wood, but these changes are not the same in all specimens. In this paper, it has been observed that the long term storage of wood influences the impact strength in bending and the permeability of wood for fluids. During the storage, there was a decrease of impact strength in bending of poplar heartwood by 28.3% and oak by 22.1% and mature beech wood by 37.3%. Also, there was decreased a permeability of wood, poplar sapwood 18.3 % and heartwood of 53.9%; oak sapwood by 20.0% and heartwood by 20.3%; beech sapwood 45.8% and mature wood by 48.2%. By decrease of the observed properties of the stored wood, a deterioration a quality of produced pulp can be expected (a higher Kappa number, amount reject and decrease the mechanical properties of pulp).

scholarly journals The Effects of Various Conditions of Short-Term Rejuvenation Heat Treatment on Room-Temperature Mechanical Properties of Thermally Aged P92 Boiler Steel

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6076
Author(s):  
Ladislav Falat ◽  
Lucia Čiripová ◽  
Viera Homolová ◽  
Miroslav Džupon ◽  
Róbert Džunda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Impact Toughness ◽  
Room Temperature ◽  
Laves Phase ◽  
Short Term ◽  
Boiler Steel ◽  
P92 Steel ◽  
The Impact

In this work, the effects of various conditions of short-term rejuvenation heat treatment on room-temperature mechanical properties of long-term aged P92 boiler steel were investigated. Normalized and tempered P92 steel pipe was thermally exposed at 600 °C for time durations up to 5000 h in order to simulate high-temperature material degradation, as also occurring in service conditions. Thus, thermally embrittled material states of P92 steel were prepared, showing tempered martensitic microstructures with coarsened secondary phase precipitates of Cr23C6-based carbides and Fe2W-based Laves phase. Compared with the initial normalized and tempered material condition, thermally aged materials exhibited a slight decrease in strength properties (i.e., yield stress and ultimate tensile strength) and deformation properties (i.e., total elongation and reduction of area). The hardness values were almost unaffected, whereas the impact toughness values showed a steep decrease after long-term ageing. An idea for designing the rejuvenation heat treatments for restoration of impact toughness was based on tuning the material properties by short-term annealing effects at various selected temperatures somewhat above the long-term ageing temperature of P92 material. Specifically, the proposed heat treatments were performed within the temperature range between 680 °C and 740 °C, employing variable heating up and cooling down conditions. It was revealed that short-term annealing at 740 °C for 1 h with subsequent rapid cooling into water represents the most efficient rejuvenation heat treatment procedure of thermally aged P92 steel for full restoration of impact toughness up to original values of normalized and tempered material state. Microstructural observations clearly indicated partial dissolution of the Laves phase precipitates to be the crucial phenomenon that played a key role in restoring the impact toughness.

scholarly journals Impact of Capital Structure on Profitability:An empirical analysis of listed firms in India

2018 ◽  
Vol 7 (2) ◽  
pp. 1-6
Author(s):  
Atif Ghayas ◽  
Javaid Akhter
Keyword(s):  
Capital Structure ◽  
Stock Exchange ◽  
Short Term ◽  
Return On Equity ◽  
Listed Firms ◽  
Relationship Capital ◽  
The Impact ◽  
The Relationship ◽  
Positive Effect

This study aims to empirically examine and analyze the impact of capital structure decision on the firm’s profitability by using a sample of 35 Indian pharmaceutical companies listed on Bombay Stock Exchange (BSE) during the period of 5 years from 2012 to 2016. Regression Analysis is used to measure the extent and nature of the relationship. Capital structure variables used in the study are ratio of long-term debt to total assets (LDA), ratio of short-term debt to total assets (SDA) and ratio of Total debt to total assets (DA) while profitability has been measure by Return on Equity (ROE). Firms Size (SIZE)and Salesgrowth(GROW) are also used as control variables. Results reveal a positive effect of SDA and DA on ROE, while a weak-to-no effect was found of LDA on ROE.

scholarly journals Damage mechanisms and embrittlement kinetics in a β-rich Ti 17 alloy after long term aging

2020 ◽  
Vol 321 ◽  
pp. 06008
Author(s):  
Layla SASAKI ◽  
Gilbert HENAFF ◽  
Mandana ARZAGHI ◽  
Patrick VILLECHAISE ◽  
Samuel HEMERY ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Detrimental Effect ◽  
Damage Tolerance ◽  
Tensile Tests ◽  
Mechanical Resistance ◽  
Damage Mechanisms ◽  
Structural Parts ◽  
The Impact

The Ti 17 (Ti-5Al-2Sn-2Zr-4Mo-4Cr) alloy is used in the first stages of engine compressors, at temperatures up to 450°C. However, its use in structural parts such as engine pylons is more prospective and raises the question of damage tolerance. As the engine pylon environment involves prolonged exposures to high temperatures, the impact of aging on mechanical properties has also to be taken in account. In this work, the consequences of a long-term aging (up to 10 000 h at 450°C) on the mechanical resistance of a Ti 17 alloy are examined at different scales, from macroscopic fatigue crack growth tests to in-situ tensile tests performed on micro samples in a SEM. The detrimental effect of aging on the mechanical properties of the Ti 17 alloy was then discussed in the light of damage mechanisms analysis and embrittlement kinetics.

scholarly journals Effect of Disinfectants on Mechanical Properties of Orthodontic Acrylics

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Tobias Bensel ◽  
Jens J. Bock ◽  
Anne Kebernik ◽  
Christin Arnold ◽  
Sonia Mansour ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Significant Influence ◽  
Colour Change ◽  
Water Disinfection ◽  
Distilled Water ◽  
Micro Hardness ◽  
Average Roughness ◽  
The Impact

Objective. Infection control protocols in dentistry dictate that orthodontic acrylics have to be disinfected. No specific products for orthodontic acrylics are available. The objective of this study was to investigate the influence of chemical disinfectants on mechanical properties of orthodontic acrylics.Materials and Methods. 260 test specimens of two cold-curing orthodontic acrylics were manufactured. Three chemical disinfecting agents were tested: Impresept, D050 Instru-Gen, and Stammopur DR. Test specimens were stored in distilled water and divided into test groups. E-Modulus, flexural strength, macro hardness, micro hardness, average roughness, and colour change were measured.Results. Disinfection agents showed no significant influence on E-modulus. Values ranged from 1783.80 ± 163.80 MPa (Forestacryl colourless) to 2474.00 ± 135.00 MPa (Orthocryl green) after storage in distilled water. Disinfection agents performed no significant influence on flexural strength. Values ranged from 18.64±1.59 N/mm2(Forestacryl colourless) to 25.64 ± 1.43 N/mm2(Orthocryl green) after storage in distilled water. Orthocryl colourless showed a reduction of the macro hardness after disinfection (Stammopur DR (p≤0.001), D050 Instru-Gen (p≤0.037)). Disinfection of Orthocryl green with D050 Instru-Gen (p<0.001) and Forestacryl colourless with Impresept (p≤0.001) led to a reduction of macro hardness. Micro hardness of Orthocryl colourless altered significantly after disinfection with D050 Instru-Gen (p≤0.001). Micro hardness of Forestacryl colourless increased (Impresept (p≤0.039)) and decreased (Stammopur DR (p≤0.006) Instru-Gen (p≤0.001)) after disinfection. Average roughness did not change significantly (Orthocryl colourless). Forestacryl colourless performed a significant change after disinfection with Stammopur DR (p≤0.05). This is also true for the disinfection of Orthocryl green and Forestacryl pink with Instru-Gen (p≤0.05). Disinfection performed no significant influence on colour change. ΔE-values were in a range of 1 to 2.Conclusions. Some orthodontic acrylics disinfection caused significant changes of determined parameters. Changes were specific for the applied disinfectant and tested orthodontic acrylic. Further studies should verify the impact of long-term disinfection intervals. Thus, from manufacturers of orthodontic acrylics recommendations for appropriate disinfectants would be desirable.

Market reaction to open innovation announcements

2018 ◽  
Vol 21 (1) ◽  
pp. 142-156 ◽  
Author(s):  
Dawid Szutowski
Keyword(s):  
Open Innovation ◽  
Information Disclosure ◽  
The European Union ◽  
Content Type ◽  
Service Companies ◽  
Significant Difference ◽  
Short And Long Term ◽  
The Impact ◽  
Positive Effect

Purpose Open innovation is of crucial importance for all companies operating in the economics of widely distributed knowledge. However, the effects of its disclosure remain largely uncharted in the case of service companies. Therefore, the purpose of this paper is to measure the impact of open innovation announcements on the market value (MV) of service enterprises. Design/methodology/approach The research covered 398 open innovation announcements released by service companies. It was conducted in the whole of the European Union in the period February 2011-December 2016. The data were analysed in the short and long term with the use of event-study and buy-and-hold methods. Findings The results indicated the significant positive effect of open innovation disclosure in both short and long term. At the same time, the market was not able to immediately fully value the information in the short run and tended to overestimate the positive effect of the innovation announced. No significant leakage and dissemination effects were observed prior to the announcement. There was no significant difference in the magnitude of positive and negative reactions to the releases. Practical implications From the point of view of business practice the research proved the benefits of information disclosure and supported the long-term planning. From the investors’ viewpoint, it signalled the small risk of significant fluctuations resulting from aggressive trading prior to the announcement and unwinding part of the acquired position afterwards. Originality/value The paper attempts to fulfil the research gap on the impact of the announcements on open innovation on the MV of companies.

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