scholarly journals Behavior of an asphalt mixture MDC-19 under the cycles of ambient temperature in the city of Tunja, Colombia

Respuestas ◽  
2019 ◽  
Vol 24 (1) ◽  
pp. 56-64
Author(s):  
Carol Rosabeth Sanabria Sanabria ◽  
Carlos Hernando Higuera Sandoval
Keyword(s):  
Ambient Temperature ◽  
Environmental Temperature ◽  
Asphalt Mixture ◽  
Early Morning ◽  
Maximum Temperature ◽  
Temperature Cycles ◽  
Weather Factor ◽  
Asphalt Mix ◽  
And Performance ◽  
Definition Of

The weather factor plays an important role in the behavior and performance of asphalt mixtures as a surface layer in a flexible pavement structure, not just from the moisture, but also from the environmental temperature. Asphalt layers of the flexible pavements in Tunja city exposes daily to environmental temperature variations, which usually occur when the highest temperatures are reached during the daytime, and the lowest temperatures appear at night and early morning time. Firstly, this research is based , on the definition of the environmental temperature cycles that occur daily in Tunja City, from the analysis of the temperature series. Subsequently, the analysis was done through laboratory tests on an asphalt mix MDC-19 INVIAS type, made and compacted in the laboratory, to determine the influence of the cycles of environmental temperature on its density, stability and flow properties, during 120 daily and continuous temperature cycles, which consist of 12 hours of maximum temperature and 12 hours of minimum temperature to simulate the environmental conditions. As a result of this investigation, the presentation density is presented, presenting a tendency to increase the measurement that increases the temperature cycles and then a decrease in the briquettes of the mixture that have sometimes been until the last cycles. Variations in the resistance to deformation of the analysis mixture were obtained as the ambient temperature cycles were sometimes made, which concludes that the ambient temperature cycles have an influence on the behavior of the asphalt mixture.

scholarly journals Prestress state evolution during thermal activation of memory effect in concrete beams strengthened with external SMA wires

2020 ◽  
Vol 20 (4) ◽  
Author(s):  
A. Debska ◽  
Piotr Gwozdziewicz ◽  
A. Seruga ◽  
X. Balandraud ◽  
J. F. Destrebecq
Keyword(s):  
Ambient Temperature ◽  
Memory Effect ◽  
Concrete Beams ◽  
Macroscopic Model ◽  
Maximum Temperature ◽  
Joule Effect ◽  
Mechanical Coupling ◽  
State Evolution ◽  
Definition Of ◽  
Concrete Elements

Abstract The memory effect of shape-memory alloys (SMAs) has opened interesting perspectives to create prestress states in concrete elements. However, the procedure has not been yet fully resolved due to the complex thermomechanical behavior of these alloys, in addition to the practical difficulties of mechanical coupling between SMA and concrete elements. The present study deals with tests on the development of prestressing forces in concrete beams during the thermal cycle required in the procedure. Pre-stretched nickel–titanium wires were externally placed on concrete prismatic beams equipped with strain gauges. As concrete rupture may occur during the heating by the Joule effect, a compromise must be found between the SMA pre-stretch level and the maximum temperature to be applied before returning to ambient temperature. A macroscopic model was developed to analyze this compromise. The complex thermomechanical response of SMAs implies a particular attention in the definition of the ambient temperature and heating conditions for the creation of prestress states in concrete components.

Картофелекопатель с ротационной сепарирующей поверхностью

2018 ◽  
Author(s):  
V.M. Alakin ◽  
G.S. Nikitin
Keyword(s):  
Performance Data ◽  
Pilot Studies ◽  
Research Results ◽  
Operating Modes ◽  
Analysis Of Results ◽  
Design Characteristics ◽  
And Performance ◽  
Definition Of

Приведены результаты исследований экспериментального картофелекопателя с ротационной сепарирующей поверхностью. Особое внимание уделяется обоснованию конструктивных параметров и определению рабочих характеристик нового сепарирующего устройства. На основе анализа результатов экспериментальных исследований определены наиболее оптимальные режимы работы экспериментального картофелекопателя.Research results of an experimental potato digger with rotational separating web are published in this article. Special attention is paid to definition of design characteristics and performance data of the new separating device. Admissible operating modes are defined on the basis of the analysis of results of pilot studies of the experimental potato digger.

Positive Workplaces

2009 ◽  
pp. 578-588
Author(s):  
Fred Luthans ◽  
Carolyn M. Youssef
Keyword(s):  
Organizational Behavior ◽  
Psychological Capital ◽  
Future Research ◽  
Positive Organizational Behavior ◽  
Performance Impact ◽  
Research Directions ◽  
Future Research Directions ◽  
And Performance ◽  
Definition Of ◽  
Psychological Capacities

Over the years, both management practitioners and academics have generally assumed that positive workplaces lead to desired outcomes. Unlike psychology, considerable attention has also been devoted to the study of positive topics such as job satisfaction and organizational commitment. However, to place a scientifically based focus on the role that positivity may play in the development and performance of human resources, and largely stimulated by the positive psychology initiative, positive organizational behavior (POB) and psychological capital (PsyCap) have recently been introduced into the management literature. This chapter first provides an overview of both the historical and contemporary positive approaches to the workplace. Then, more specific attention is given to the meaning and domain of POB and PsyCap. Our definition of POB includes positive psychological capacities or resources that can be validly measured, developed, and have performance impact. The constructs that have been determined so far to best meet these criteria are efficacy, hope, optimism, and resiliency. When combined, they have been demonstrated to form the core construct of what we term psychological capital (PsyCap). A measure of PsyCap is being validated and this chapter references the increasing number of studies indicating that PsyCap can be developed and have performance impact. The chapter concludes with important future research directions that can help better understand and build positive workplaces to meet current and looming challenges.

The Performance of Styrene Butadiene Rubber on the Engineering Properties of Asphaltic Concrete AC14

2016 ◽  
Vol 700 ◽  
pp. 238-246 ◽  
Author(s):  
Dewi Sri Jayanti ◽  
Ramadhansyah Putra Jaya ◽  
Siti Aspalaili Mohamd Sharif ◽  
Norhidayah Abdul Hassan ◽  
Siti Nur Amiera Jeffry ◽  
...  
Keyword(s):  
Resilient Modulus ◽  
Asphalt Mixture ◽  
Engineering Properties ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Asphaltic Concrete ◽  
Dynamic Creep ◽  
Creep Stiffness ◽  
And Performance ◽  
Styrene Butadiene

This study investigated the effects of adding various percentages of styrene–butadiene rubber (SBR) on the engineering properties and performance of asphaltic concrete. SBR was added into the mixture at 0%, 1%, 3%, and 5% on a mass-to-mass basis. Conventional bitumen used in this study was 80/100 PEN. The performances of SBR on the asphalt mixture properties were evaluated based on Marshall Stability, abrasion loss, resilient modulus, and dynamic creep test. Results indicated an improvement in the engineering properties and performance with the addition of SBR content. For instance, stability increased by 18.8% as the SBR content increased from 0% to 5%. Dynamic creep stiffness also increased by 46.2%. Similarly, the resilient modulus was also found to increase by approximately 84.6%.

Performance of Asphalt Mixture Used for Asphalt Treated Base of Perpetual Pavements

2011 ◽  
Vol 415-417 ◽  
pp. 1531-1536
Author(s):  
Fu Ming Liu ◽  
Duan Yi Wang
Keyword(s):  
Tensile Strain ◽  
Performance Test ◽  
Asphalt Mixture ◽  
Fatigue Tests ◽  
Asphalt Pavements ◽  
Moisture Susceptibility ◽  
Scale Test ◽  
And Performance ◽  
Wheel Tracking ◽  
Fatigue Endurance

This paper presents the results of laboratory and performance tests for an asphalt treated base (ATB) and mixes developed in this study for perpetual asphalt pavements. Laboratory tests for the mixes included moisture susceptibility, wheel tracking and fatigue tests. The results of performance test indicated that the resistances of the high content binder ATB against moisture and fatigue damage were better than those of the lower one. It was also found from the full scale test sections that the tensile strain values at the bottom of the asphalt layer for the ATB sections were low when the asphalt layer thicknesses of the ATB sections were not thicker than those of the conventional sections. All the tensile strain values measured from the ATB sections were within the fatigue endurance limit of 70 microstrain which is the fatigue criterion of a perpetual asphalt pavement.

Design and Fabrication of a Magnetocaloric Microcooler

2005 ◽  
Author(s):  
Sangchae Kim ◽  
Bharath Bethala ◽  
Simone Ghirlanda ◽  
Senthil N. Sambandam ◽  
Shekhar Bhansali
Keyword(s):  
Magnetic Field ◽  
Ambient Temperature ◽  
Temperature Change ◽  
Entropy Change ◽  
Temperature Sensors ◽  
Experimental Results ◽  
Maximum Temperature ◽  
Alternative Technology ◽  
Temperature Conditions ◽  
Si Wafer

Magnetocaloric refrigeration is increasingly being explored as an alternative technology for cooling. This paper presents the design and fabrication of a micromachined magnetocaloric cooler. The cooler consists of fluidic microchannels (in a Si wafer), diffused temperature sensors, and a Gd5(Si2Ge2) magnetocaloric refrigeration element. A magnetic field of 1.5 T is applied using an electromagnet to change the entropy of the magnetocaloric element for different ambient temperature conditions ranging from 258 K to 280 K, and the results are discussed. The tests show a maximum temperature change of 7 K on the magnetocaloric element at 258 K. The experimental results co-relate well with the entropy change of the material.

Trained Helping Behaviors and Group Performance

1991 ◽  
Vol 68 (3_suppl) ◽  
pp. 1291-1298
Author(s):  
Nancy J. Stone ◽  
Molly E. O'Gorman
Keyword(s):  
Group Performance ◽  
Group Members ◽  
Helping Behaviors ◽  
And Performance ◽  
Definition Of ◽  
Crossword Puzzles

96 students assigned to 32 groups were trained in seeking information to judge whether particular helping behaviors would increase application of the behavior found positively correlated with performance. Three-person groups worked crossword puzzles which decreased in difficulty over two trials. Training significantly increased seeking behaviors and performance (reduced errors). Helping behaviors were also more useful when the task was difficult and not helpful when the task was easy, which supports the notion that helping behaviors may even be debilitating under certain circumstances. More research is needed to establish a functional definition of helping behaviors and to investigate the use of helping behaviors on tasks requiring interdependence among group members.

scholarly journals Open-book accounting and trust: influence on buyer-supplier relationship

2018 ◽  
Vol 53 (4) ◽  
pp. 597-621 ◽  
Author(s):  
Lara Cristina Francisco de Almeida Fehr ◽  
Welington Rocha
Keyword(s):  
Data Gathering ◽  
Structured Interview ◽  
Information Value ◽  
Open Book ◽  
Information Process ◽  
Content Type ◽  
And Performance ◽  
Definition Of ◽  
New Research ◽  
Supplier Relationship

PurposeThis paper aims to discuss the role of open-book accounting (OBA) and trust on buyer–supplier relationship satisfaction. The objective of this paper is to analyze how OBA and trust influence satisfaction on the relationship between suppliers and buyers in the Brazilian automotive sector’s supply chain.Design/methodology/approachThe research has been developed based on a qualitative strategy, characterized as explanatory. Data gathering has been conducted through document analysis and semi-structured interview, and content analysis has been used for discourse analysis.FindingsResults show that OBA is unilateral, imposed by the auto manufacturer, representing a selective information process, as suppliers try to protect their information value as far as possible. Trust is partial and cooperation is not spontaneous, both driven by the search for benefits. OBA may yield a positive or a negative outcome with regard to the social and the economic overall satisfaction of suppliers, depending on how the information is used by auto manufacturer.Originality/valueThe main contribution of this article is to provide an understanding of the difficulties of applying the OBA in companies and of the factors that may influence its operation and performance, impacting on satisfaction and continuity of relationships. The paper also contributes with the proposal of a clearer and more objective definition of OBA. Being the intention that new research in this area can be developed from a delimited, clear and objective definition of OBA, allowing better understanding on the subject and comparison among research studies.

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