A Study on Optical Fiber Damage Due to Optoelectronic Assembly Processes

2005 ◽  
Author(s):  
Kaustubh R. Nagarkar ◽  
Peter Borgesen ◽  
Krishnaswami Srihari
Keyword(s):  
Optical Fibers ◽  
Fiber Optic ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Sem Analysis ◽  
Primary Sources ◽  
Mechanical Degradation ◽  
Fiber Damage ◽  
The Individual ◽  
The Impact

Optoelectronic assembly processes, such as laser and photodiode packaging, connector assembly, and splicing, tend to involve extensive handling of optical fibers. These processes offer considerable likelihood of inducing severe damage to the fibers. Such damage degrades the strength of optical fibers and could result in lower than expected lifetimes in service. The objective of this research was to investigate the impact of fiber-optic assembly processes on the mechanical performance of optical fibers. Certain applications such as fiber-optic splices, connectors, and optoelectronic packages require that the protective coating of the fibers be removed through a process called ‘fiber-stripping’. The process of ‘fiber-stripping’ was characterized to identify the primary sources of mechanical degradation. The related handling and cleaning steps were also evaluated. Further, the process steps in the assembly of fiber optic connectors were closely examined and the impact of assembling fibers into adhesives was tested. Qualitative and quantitative tools have been used to investigate the problems and have been discussed in this paper. Tensile tests were used to compare the mechanical performance of the fibers. Special fixtures and test set-ups were created that enabled the testing of the fibers. Characterization techniques, such as Scanning Electron Microscopy (SEM) analysis and optical microscopy, were also used. The results have enabled to identify the contributions of the individual assembly steps that impair the strength of optical fibers. This paper provides an understanding of the potential sources and mechanisms of degradation due to such processes.

Experimental Investigations on the Influence of Temperature on the Behavior of Steel Reinforcement (Strands and Rebars)

2016 ◽  
Vol 711 ◽  
pp. 908-915
Author(s):  
Wiem Toumi Ajimi ◽  
Sylvain Chataigner ◽  
Yannick Falaise ◽  
Laurent Gaillet
Keyword(s):  
Prestressed Concrete ◽  
Temperature Increase ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Steel Reinforcement ◽  
Experimental Investigations ◽  
Tensile Behaviour ◽  
Nuclear Containment ◽  
Different Temperatures ◽  
The Impact

In the case of exceptional accidents, nuclear containment structures may be submitted to an internal temperature increase. This may have an influence on the prestressed concrete structures behavior regarding both its mechanical performance and its porosity. The presented study got interested on the impact that a temperature increase may have on the mechanical behavior of the steel reinforcement for both prestressing strands and rebars. In order to remain in realistic situations, it was chosen to study temperatures between 20°C and 140°C. Some experimental investigations regarding the tensile behaviour of steel rebars and their adherence within concrete will first be presented. Then, some investigations on steel strands will be described: some tensile tests at different temperatures, and some relaxation tests to check how the level of prestress loss may be affected by the temperature. This experimental study is part of a national French project (MACENA) aiming at assessing the impact of an accident on the behavior of nuclear containment structures. The gathered experimental data will be used for their damage assessment.

Efficient Optical Couplings for Fiber-Distributed Solar Lighting

Solar Energy ◽  
2003 ◽  
Author(s):  
L. C. Maxey ◽  
M. R. Cates ◽  
S. L. Jaiswal
Keyword(s):  
Optical Fibers ◽  
Optical Waveguides ◽  
Large Core ◽  
Index Matching ◽  
Refractive Index Matching ◽  
Solar Lighting ◽  
The Individual ◽  
Insertion Losses ◽  
The Impact ◽  
Loss Mechanisms

Optical couplings in large core optical waveguides have many similarities with those in conventional optical fibers but pose some unconventional challenges as well. The larger geometry, looser manufacturing tolerances and reduced dimensional stability compound the problems associated with making low-loss couplings in large core waveguides. The individual factors contributing to coupling losses are discussed to develop an understanding of the extant loss mechanisms. Individual methods and materials employed to mitigate the impact of each of the dominant loss mechanisms are discussed in detail. A combination of endface geometry control, axial alignment constraint and refractive index matching are employed to produce highly efficient optical couplings in large core waveguides. The combination of these elements has significantly reduced the insertion losses due to connector couplings. Prior to implementing the current methods losses of 15% and greater were common but these have been reduced to 2%–5% with the current methods.

Microscopical Observations of the Abrasive and Ultraviolet Deterioration of Nomex® Aramid Fiber

1977 ◽  
Vol 47 (3) ◽  
pp. 171-177
Author(s):  
Barbara Hodam Kirkwood
Keyword(s):  
Fiber Surface ◽  
Strength Loss ◽  
Surface Damage ◽  
Tensile Tests ◽  
Fiber Fracture ◽  
Fiber Damage ◽  
Gas Formation ◽  
Fracture Patterns ◽  
The Individual ◽  
Original Production

Nomex® trousers which had been worn by Army helicopter personnel were compared in the scanning electron microscope (SEM) to material which was ultraviolet-(uv-) irradiated and/or Accelerotor-abraded. Samples which were both uv-irradiated and abraded had greater strength loss and more fiber surface damage. Wear initiated through peeling, either on the fiber surface or along cracks that formed in the depressed center of the “dogbone” shaped fiber. Short fibrillation eventually caused fiber severing. The Accelerotor reproduced the individual fiber damage observed in field-worn Nomex, but distribution of wear within damaged yarns was different. SEM examination revealed thatuv radiation aggravated the decomposition and gas formation in Nomex fiber ends which had been exposed to a singeing flame, resulting in burst bubbles with rough surfaces and jagged edges. This condition is thought to be associated with reported tactile discomfort with original production lots which had been singed. Fiber-fracture patterns from fabric tensile tests were quite variable, and no distinct trends were observed.

scholarly journals Poly(ε-Caprolactone)/Brewers’ Spent Grain Composites—The Impact of Filler Treatment on the Mechanical Performance

2020 ◽  
Vol 4 (4) ◽  
pp. 167
Author(s):  
Aleksander Hejna
Keyword(s):  
Chemical Structure ◽  
Mechanical Performance ◽  
Natural Fiber ◽  
Reactive Extrusion ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Mechanical Tests ◽  
Interface Surface ◽  
Spent Grain ◽  
The Impact

Waste lignocellulose materials, such as brewers’ spent grain, can be considered very promising sources of fillers for the manufacturing of natural fiber composites. Nevertheless, due to the chemical structure differences between polymer matrices and brewers’ spent grain, filler treatment should be included. The presented work aimed to investigate the impact of fillers’ reactive extrusion on the chemical structure and the poly(ε-caprolactone)/brewers’ spent grain composites’ mechanical performance. The chemical structure was analyzed by Fourier-transform infrared spectroscopy, while the mechanical performance of composites was assessed by static tensile tests and dynamic mechanical analysis. Depending on the filler pretreatment, composites with different mechanical properties were obtained. Nevertheless, the increase in pretreatment temperature resulted in the increased interface surface area of filler, which enhanced composites’ toughness. As a result, composites were able to withstand a higher amount of stress before failure. The mechanical tests also indicated a drop in the adhesion factor, pointing to enhanced interfacial interactions for higher pretreatment temperatures. The presented work showed that reactive extrusion could be considered an auspicious method for lignocellulose filler modification, which could be tailored to obtain composites with desired properties.

Accent Policy and Accent Modification Enterprises as Potential Indicators of Intercultural Power Relations: A Call for an Updated Research Agenda

2013 ◽  
Vol 3 (1) ◽  
pp. 22-33 ◽  
Author(s):  
Brynne D. Ovalle ◽  
Rahul Chakraborty
Keyword(s):  
International Relations ◽  
Identity Construction ◽  
Social Theory ◽  
Power Relations ◽  
Linguistic Diversity ◽  
Cultural Organization ◽  
Using Data ◽  
The Individual ◽  
The Impact ◽  
The Relationship

This article has two purposes: (a) to examine the relationship between intercultural power relations and the widespread practice of accent discrimination and (b) to underscore the ramifications of accent discrimination both for the individual and for global society as a whole. First, authors review social theory regarding language and group identity construction, and then go on to integrate more current studies linking accent bias to sociocultural variables. Authors discuss three examples of intercultural accent discrimination in order to illustrate how this link manifests itself in the broader context of international relations (i.e., how accent discrimination is generated in situations of unequal power) and, using a review of current research, assess the consequences of accent discrimination for the individual. Finally, the article highlights the impact that linguistic discrimination is having on linguistic diversity globally, partially using data from the United Nations Educational, Scientific and Cultural Organization (UNESCO) and partially by offering a potential context for interpreting the emergence of practices that seek to reduce or modify speaker accents.

Investigating the Relationship Between Self-Esteem and Stigma Among Young Adults With History of Suicide Attempts

Crisis ◽  
2016 ◽  
Vol 37 (4) ◽  
pp. 265-270 ◽  
Author(s):  
Meshan Lehmann ◽  
Matthew R. Hilimire ◽  
Lawrence H. Yang ◽  
Bruce G. Link ◽  
Jordan E. DeVylder
Keyword(s):  
Young Adults ◽  
Suicide Attempts ◽  
Self Esteem ◽  
High Risk Population ◽  
High Functioning ◽  
People With Mental Illness ◽  
History Of ◽  
The Individual ◽  
The Impact ◽  
The Relationship

Abstract. Background: Self-esteem is a major contributor to risk for repeated suicide attempts. Prior research has shown that awareness of stigma is associated with reduced self-esteem among people with mental illness. No prior studies have examined the association between self-esteem and stereotype awareness among individuals with past suicide attempts. Aims: To understand the relationship between stereotype awareness and self-esteem among young adults who have and have not attempted suicide. Method: Computerized surveys were administered to college students (N = 637). Linear regression analyses were used to test associations between self-esteem and stereotype awareness, attempt history, and their interaction. Results: There was a significant stereotype awareness by attempt interaction (β = –.74, p = .006) in the regression analysis. The interaction was explained by a stronger negative association between stereotype awareness and self-esteem among individuals with past suicide attempts (β = –.50, p = .013) compared with those without attempts (β = –.09, p = .037). Conclusion: Stigma is associated with lower self-esteem within this high-functioning sample of young adults with histories of suicide attempts. Alleviating the impact of stigma at the individual (clinical) or community (public health) levels may improve self-esteem among this high-risk population, which could potentially influence subsequent suicide risk.

High-voltage monitoring by the fiber-optic recirculating measuring system

2020 ◽  
pp. 38-44
Author(s):  
A. V. Polyakov ◽  
M. A. Ksenofontov
Keyword(s):  
Optical Fibers ◽  
High Voltage ◽  
Optical Sensors ◽  
Electromagnetic Interference ◽  
Fiber Optic ◽  
Electric Power Industry ◽  
Measuring System ◽  
Voltage Range ◽  
External Electromagnetic Fields ◽  
Optic Communication

Optical technologies for measuring electrical quantities attract great attention due to their unique properties and significant advantages over other technologies used in high-voltage electric power industry: the use of optical fibers ensures high stability of measuring equipment to electromagnetic interference and galvanic isolation of high-voltage sensors; external electromagnetic fields do not influence the data transmitted from optical sensors via fiber-optic communication lines; problems associated with ground loops are eliminated, there are no side electromagnetic radiation and crosstalk between the channels. The structure and operation principle of a quasi-distributed fiber-optic high-voltage monitoring system is presented. The sensitive element is a combination of a piezo-ceramic tube with an optical fiber wound around it. The device uses reverse transverse piezoelectric effect. The measurement principle is based on recording the change in the recirculation frequency under the applied voltage influence. When the measuring sections are arranged in ascending order of the measured effective voltages relative to the receiving-transmitting unit, a relative resolution of 0,3–0,45 % is achieved for the PZT-5H and 0,8–1,2 % for the PZT-4 in the voltage range 20–150 kV.

The Role of Threat and Economic Uncertainty in Support for Scottish Independence

2014 ◽  
Vol 23 (1) ◽  
pp. 103-124 ◽  
Author(s):  
Daniel Kopasker
Keyword(s):  
Economic Consequences ◽  
Perceived Threat ◽  
Constitutional Change ◽  
Lack Of Information ◽  
Economic Expectations ◽  
Scottish Independence ◽  
The Individual ◽  
The Impact ◽  
Levels Of Support

Existing research has consistently shown that perceptions of the potential economic consequences of Scottish independence are vital to levels of support for constitutional change. This paper attempts to investigate the mechanism by which expectations of the economic consequences of independence are formed. A hypothesised causal micro-level mechanism is tested that relates constitutional preferences to the existing skill investments of the individual. Evidence is presented that larger skill investments are associated with a greater likelihood of perceiving economic threats from independence. Additionally, greater perceived threat results in lower support for independence. The impact of uncertainty on both positive and negative economic expectations is also examined. While uncertainty has little effect on negative expectations, it significantly reduces the likelihood of those with positive expectations supporting independence. Overall, it appears that a general economy-wide threat is most significant, and it is conjectured that this stems a lack of information on macroeconomic governance credentials.

Microstructural and Mechanical Behaviour Evaluation of Mg-Al-Zn Alloy Friction Stir Welded Joint

2020 ◽  
Vol 17 (3) ◽  
pp. 8150-8159
Author(s):  
Kulwant Singh ◽  
Gurbhinder Singh ◽  
Harmeet Singh
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Magnesium Alloys ◽  
Mechanical Performance ◽  
Fuel Efficiency ◽  
Research Work ◽  
Grain Structure ◽  
Tensile Fracture ◽  
Friction Stir ◽  
The Impact

The weight reduction concept is most effective to reduce the emissions of greenhouse gases from vehicles, which also improves fuel efficiency. Amongst lightweight materials, magnesium alloys are attractive to the automotive sector as a structural material. Welding feasibility of magnesium alloys acts as an influential role in its usage for lightweight prospects. Friction stir welding (FSW) is an appropriate technique as compared to other welding techniques to join magnesium alloys. Field of friction stir welding is emerging in the current scenario. The friction stir welding technique has been selected to weld AZ91 magnesium alloys in the current research work. The microstructure and mechanical characteristics of the produced FSW butt joints have been investigated. Further, the influence of post welding heat treatment (at 260 °C for 1 h) on these properties has also been examined. Post welding heat treatment (PWHT) resulted in the improvement of the grain structure of weld zones which affected the mechanical performance of the joints. After heat treatment, the tensile strength and elongation of the joint increased by 12.6 % and 31.9 % respectively. It is proven that after PWHT, the microhardness of the stir zone reduced and a comparatively smoothened microhardness profile of the FSW joint obtained. No considerable variation in the location of the tensile fracture was witnessed after PWHT. The results show that the impact toughness of the weld joints further decreases after post welding heat treatment.

Effect of Organizational Culture and Organizational Commitment to Employee Performance through Organizational Citizenship Behavior (OCB) as Intervening Variables (Study on Bappeda Litbang Provinsi Bali)

2018 ◽  
Vol 9 (08) ◽  
pp. 20997-21013
Author(s):  
Anom Suwibawa ◽  
Anak Agung Putu Agung ◽  
I Ketut Setia Sapta
Keyword(s):  
Organizational Culture ◽  
Organizational Commitment ◽  
Organizational Citizenship ◽  
Organizational Citizenship Behavior ◽  
Structural Equation ◽  
Employee Performance ◽  
Sem Analysis ◽  
Citizenship Behavior ◽  
Equation Modeling ◽  
The Individual

Organizational culture as the values, principles, traditions and ways of working shared by members of the organization and affect the way they act. Organizational commitment has an important role of employee performance. The commitment can be realized if the individual in the organization, running their rights and obligations according to their duties and functions and functions within the organization, because the achievement of organizational goals is the work of all members of the organization that are collective Vipraprastha, Sudja,  & Yuesti (2018). Respondents in this study are Civil Servants (PNS) at least have been working for 2 years. The number of respondents in this study were 86 respondents using Nonprobability technique that is saturated samples or often called total sampling. This research uses SMARTPLS 3 Structural Equation Modeling (SEM) analysis. The results of this study indicate that: 1) organizational culture has a positive and significant effect on Organizational Citizenship Behavior (OCB); 2) Organizational Citizenship Behavior (OCB) has positive and significant impact on Organizational Citizenship Behavior (OCB); 3) Organizational Citizenship Behavior employee, 4) organizational culture has a positive effect on the performance of employees, either partially or through Organizational Citizenship Behavior (OCB), 5) Organizational commitment has no effect on employee performance.

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