scholarly journals Fabrication of Alumina Doped Optical Fiber Preforms by MCVD-Metal Chelate Doping Method

Author(s):  
K.A. Mat Sharif ◽  
Nasr Y.M. Omar ◽  
M.I. Zulkifli ◽  
S.Z. Muhamad Yassin ◽  
H.A. Abdul-Rashid

This paper reports on the fabrication of alumina doped preforms using MCVD-vapor phase chelate delivery system with Al(acac)3 as the precursor. The objectives of the work are to study the deposition process, the efficiency of the fabrication process, and the quality of the fabricated fiber preforms. Two parameters are studied, Al(acac)3 sublimator temperature (TAl°C) and deposition direction (i.e. downstream and upstream). Other parameters such as oxygen flow and deposition temperature are fixed. The results showed that a high uniformity of refractive index difference (%RSD < 2%) and core size (%RSD < 2.4%) was obtained along the preform length using downstream deposition while for the combined upstream and downstream deposition the uniformity was deteriorated. The process efficiency was found to be about 21% for TAl°C of 185°C and downstream deposition. From the EDX elemental analysis, the refractive index was found to increase by 0.0025 per mole percent of alumina.

2020 ◽  
Vol 10 (20) ◽  
pp. 7231
Author(s):  
K. A. Mat Sharif ◽  
N. Y. M. Omar ◽  
M. I. Zulkifli ◽  
S. Z. Muhamad Yassin ◽  
H. A. Abdul-Rashid

This paper reports on the fabrication of alumina-doped preforms using a modified chemical vapor deposition (MCVD)-vapor phase chelate delivery system with Al(acac)3 as the precursor. The objectives of this work are to study the deposition process, the efficiency of the fabrication process, and the quality of the fabricated fiber preforms. Two parameters are studied, the Al(acac)3 sublimator temperature (TAl °C) and the deposition direction (i.e., downstream and upstream). Other parameters such as the oxygen flow and deposition temperature are fixed. The results show that high uniformity of the refractive index difference (%RSD < 2%) and core size (%RSD < 2.4%) was obtained along the preform length using downstream deposition, while for the combined upstream and downstream deposition, the uniformity deteriorated. The process efficiency was found to be about 21% for TAl °C of 185 °C and downstream deposition. From the EDX elemental analysis, the refractive index was found to increase by 0.0025 per mole percent of alumina.


1973 ◽  
Vol 54 ◽  
pp. 173-221
Author(s):  
J. C. Pecker

Regardless of the degree of elaboration of series of models, just how can they be used for calibration purposes? And how much is this calibration sensitive to the quality of the model theory? These two questions are the basis of our discussion, which covers : I – The general principles of the use of model atmospheres in stellar calibration (1 – The two dimensional classifications; 2 – The use of the total luminosity; 3 – The cases of Vega and Sirius; 4 – The calibration of ST – Teff relation); II – The failures of the two parameters model atmospheres (1 – The observational need for more-than-two-parameters classification; 2 – The abundance of elements, the line formation, and the model atmospheres; 3 – Various sources of unadequacy of models; 4 – Envelopes or shell features; their influence on model-building; 5 – The case of HD 45677. Diagnostic of early-type stars; 6 – Various unexplained spectral features); III – The present state of the model factory (1 – The classical models; 2 – New concepts in the description of a stellar atmosphere; 3 – New approaches in model making; 4 – Conclusions).


2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Naokazu Murata ◽  
Naoki Saito ◽  
Kinji Tamakawa ◽  
Ken Suzuki ◽  
Hideo Miura

Effects of crystallographic quality of grain boundaries on mechanical and electrical properties were investigated experimentally. A novel method using two parameters of image quality (IQ) and confidence index (CI) values based on electron back-scattering diffraction (EBSD) analysis was proposed in order to evaluate crystallographic quality of grain boundaries. IQ value was defined as an index to evaluate crystallinity in region irradiated with electron beam. CI value determined existence of grain boundaries in the region. It was found that brittle intergranular fatigue fracture occurred in the film without annealing and the film annealed at 200 °C because network of grain boundaries with low crystallinity remained in these films. On the other hand, the film annealed at 400 °C caused only ductile transgranular fatigue fracture because grain boundaries with low crystallinity almost disappeared. From results of measurement of electrical properties, electrical resistivity of copper interconnection annealed at 400 °C with high crystallinity (2.09 × 10−8 Ωm) was low and electron migration (EM) resistance was high compared with an copper interconnection without annealing with low crystallinity (3.33 × 10−8 Ωm). It was clarified that the interconnection with high crystallinity had superior electrical properties. Thus, it was clarified that the crystallographic quality of grain boundaries has a strong correlation of mechanical and electrical reliability.


Author(s):  
Volodymyr Fedorov ◽  
Halyna Filipova ◽  
Vasyl Yanovsky

High-quality military equipment is a vital necessity for the independent state of Ukraine, especially in the conditions of aggravation of the situation at the front. One of the parameters that determines the quality of military vehicles is the level of external noise. The external noise of this type of car, in addition to the negative impact on human health (including the crew), is also an unmasking factor. In order to reduce the level of external noise of SPAI “Bogdan” on the basis of the chassis KrAZ-63221, the use of an advanced two-chamber jet muffler of the exhaust gases of the internal combustion engine is proposed. The known two-chamber jet muffler of exhaust gases has a fixed internal partition. Its acoustic efficiency is described by a known formula. It is proposed to make the inner partition of the muffler movable. This need arises from the fact of constant changes in the speed of the engine crankshaft during the movement of the car. The change in the position of the inner partition is consistent with the change in the speed of the crankshaft, because these two processes are synchronized. The mathematical package IDL was used to analyze the known formula for the efficiency of a two-chamber jet exhaust muffler of an engine with a movable inner partition. Given the need to show the dependence of the efficiency of the muffler simultaneously on two parameters – the speed of the crankshaft and the position of the movable inner partition of the muffler – the method of color coding was chosen. The design of a two-chamber jet noise muffler developed for ACS “Bogdan” is given. As a result of introduction of the developed muffler noise reduction of level of external noise of the SPAI “Bogdan” on the basis of the chassis KrAZ-63221 car on 2–3,5 dBA in the range of speeds of movement of 45–85 km/h is forecasted.


2012 ◽  
Vol 77 (9) ◽  
pp. 1239-1242
Author(s):  
Rastko Vasilic

The development of a new method for epitaxial growth of metals in solution by galvanic displacement of layers pre-deposited by underpotential deposition (UPD) was discussed and experimentally illustrated throughout the lecture. Cyclic voltammetry (CV) and scanning tunneling microscopy (STM) are employed to carry out and monitor a ?quasi-perfect?, two-dimensional growth of Ag on Au(111), Cu on Ag(111), and Cu on Au(111) by repetitive galvanic displacement of underpotentially deposited monolayers. A comparative study emphasizes the displacement stoichiometry as an efficient tool for thickness control during the deposition process and as a key parameter that affects the deposit morphology. The excellent quality of layers deposited by monolayer-restricted galvanic displacement is manifested by a steady UPD voltammetry and ascertained by a flat and uniform surface morphology maintained during the entire growth process.


Author(s):  
J. Damisa ◽  
J. O. Emegha ◽  
I. L. Ikhioya

Lead tin sulphide (Pb-Sn-S) thin films (TFs) were deposited on fluorine-doped tin oxide (FTO) substrates via the electrochemical deposition process using lead (II) nitrate [Pb(NO3)2], tin (II) chloride dehydrate [SnCl2.2H2O] and thiacetamide [C2H5NS] precursors as sources of lead (Pb), tin (Sn) and sulphur (S). The solution of all the compounds was harmonized with a stirrer (magnetic) at 300k. In this study, we reported on the improvements in the properties (structural and optical) of Pb-Sn-S TFs by varying the deposition time. We observed from X-ray diffractometer (XRD) that the prepared material is polycrystalline in nature. UV-Vis measurements were done for the optical characterizations and the band gap values were seen to be increasing from 1.52 to 1.54 eV with deposition time. In addition to this, the absorption coefficient and refractive index were also estimated and discussed.


1980 ◽  
Vol 95 (2) ◽  
pp. 471-485 ◽  
Author(s):  
D. J. Greenwood ◽  
T. J. Cleaver ◽  
Mary K. Turner ◽  
J. Hunt ◽  
K. B. Niendorf ◽  
...  

SUMMARYThe effect of level of N fertilizer on the composition, yield and quality of 21 crops was studied in experiments on adjacent sites of the same field to aid in the development of fertilizer recommendations.Yield of each of the crops first increased and then either remained the same or declined with further increases of N fertilizer. Interpretation by means of a simple model enabled response curves to be characterized by two parameters; one representing the beneficial component of the response and the other the detrimental component. Both varied greatly from crop to crop.The magnitude of the beneficial component of the response of most non-leguminous crops was largely determined by the potential demand of the crop for nitrogen; the exceptions were some root crops which responded less than would be expected on this basis. The adverse component was serious with root crops and those crops that are in the soil for only a short period. High levels of N increased the ratio of foliage to storage root dry weights even when total dry matter was unaffected. The changes were associated with a considerable increase in the % N in the dry matter of the roots.When crops were grown with their optimum levels of N fertilizer a simple linear. relationship between the mean %N in the dry matter and the total weight of dry matter per unit area covered all crops. Simple relationships also existed between total dry matter of non-leguminous crops and (a) the amount of N taken up by the crop from unfertilized soil, (b) the recovery of added fertilizer by the crop and (c) the beneficial component of the response of crops harvested before October.Percentage N in the dry matter at harvest was not a sensitive indicator of the extent to which plant growth was restricted by lack of nitrogen; a difference of 0·1% N in the plant material was associated with a 10% increase in yield.N fertilizer levels influenced the % dry matter and the incidence of crop disorders such as rotten roots and tissue discoloration, but the effects were seldom appreciable with practicable levels of fertilizer application.


2021 ◽  
Author(s):  
Hendrik Suryadi ◽  
Haifeng Li ◽  
Diego Medina ◽  
Alex Celis

Abstract Drilling wells with minimum risk and optimizing well placement with the least possible cost are key goals that companies strive to achieve. The major contributor to the successful execution of the well is the quality of the drilling program. Well design is a complex process, which requires full collaboration of multiple domain roles & expertise working together to integrate various well-planning data. Many design challenges will be encountered, such as risk assessments, domain-specific workflows, geological concerns, technology selections, cost & time estimation, environmental and safety concerns. Design process efficiency depends on effective communication between parties, quickly adapting to any changes, reducing the number of changes, and reducing complicated & manual processes. Current existing workflow and tools are not promoting an excellent collaborative environment among the different roles involved. Engineers utilize multiple engineering applications, which involved many manual data transfers and inputs. The different party is still working in a silo and sharing the design via email or other manual data transfer. Any changes to the design cause manual rework, leading to inconsistency, incoherency, slow decision & optimization process, and failure to identify all potential risks, increasing the well planning time. The new digital planning solution based on cloud technology allows the design team to maximize the results by giving them access to all the data and science they need in a single, standard system. It's a radical new way of working that gives engineers quicker and better-quality drilling programs by automating repetitive tasks and validation workflows to ensure the entire plan is coherent. This new planning solution allows multiple roles & domain collaboration to break down silos, increase team productivity through tasks assignment, and share all data. An automated trajectory design changes the way engineers design trajectory from manually connecting the path from a surface location to the target reservoir location to automatically calculate & propose multiple options with various KPIs allowing the engineer to select the best trajectory option. The system reinforces drilling program quality through auto engineering analysis, which provides quick feedback for any design changes and provides an integrated workflow from the trajectory design to operational activity planning and AFE. The automation of repetitive tasks, such as multiple manual inputs, frees domain experts to have more time to focus on creating new engineering insights while still maintaining design traceability to review updates over the life of the projects and see how the design changes have optimized the drilling program. This new solution solves some of the significant challenges in the current well-planning workflow.


2013 ◽  
Vol 2 (2) ◽  
pp. 54-62 ◽  
Author(s):  
Shima Tabatabai

The article summarizes evidence about the effectiveness of patient–physician electronic communication. The emphasis was on the importance of understanding the potential impact of e-communication on patient satisfaction, and on the quality of health care. A review of literature was performed in the area of patient–physician electronic communication, and references were appraised, and synthesized for an overview of benefits and challenges of this model of communication. Electronic communication is becoming popular, has the potential to transform the health care system, and support the patient–physician interaction. Patients are enthusiastic about this convenience model of communication, and feel strongly embraced in communicating via email & web messaging. Although, there is evidence that electronic communication could increase quality of care due to increased interaction and would extend health care efficiency, a variety of potential benefits and challenges is reported. Overall, electronic communication introduces a new model of patient-physician interaction that could supplement and reasonably replace a portion of traditional face-to-face encounters. However, further investigation is required to assess its impact on healthcare process efficiency.


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