scholarly journals Quick Fabrication VCSELs for Characterisation of Epitaxial Material

2021 ◽  
Vol 11 (20) ◽  
pp. 9369
Author(s):  
Jack Baker ◽  
Craig P. Allford ◽  
Sara-Jayne Gillgrass ◽  
Richard Forrest ◽  
David G. Hayes ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Threshold Current ◽  
Cavity Resonance ◽  
Sufficient Information ◽  
Substrate Thickness ◽  
Structural Elements ◽  
Lasing Wavelength ◽  
Systematic Analysis ◽  
Time Required ◽  
The Impact

A systematic analysis of the performance of VCSELs, fabricated with a decreasing number of structural elements, is used to assess the complexity of fabrication (and therefore time) required to obtain sufficient information on epitaxial wafer suitability. Initially, sub-mA threshold current VCSEL devices are produced on AlGaAs-based material, designed for 940 nm emission, using processing methods widely employed in industry. From there, stripped-back Quick Fabrication (QF) devices, based on a bridge-mesa design, are fabricated and this negates the need for benzocyclcobutane (BCB) planarisation. Devices are produced with three variations on the QF design, to characterise the impact on laser performance from removing time-consuming process steps, including wet thermal oxidation and mechanical lapping used to reduce substrate thickness. An increase in threshold current of 1.5 mA for oxidised QF devices, relative to the standard VCSELs, and a further increase of 1.9 mA for unoxidised QF devices are observed, which is a result of leakage current. The tuning of the emission wavelength with current increases by ~0.1 nm/mA for a VCSEL with a 16 μm diameter mesa when the substrate is unlapped, which is ascribed to the increased thermal resistance. Generally, relative to the standard VCSELs, the QF methods employed do not significantly impact the threshold lasing wavelength and the differences in mean wavelengths of the device types that are observed are attributed to variation in cavity resonance with spatial position across the wafer, as determined by photovoltage spectroscopy measurements.

Experimental Analysis of Heat Transfer From Ice Rink Floors

Solar Energy ◽  
2006 ◽  
Author(s):  
Jung Mun ◽  
Moncef Krarti
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Thermal Insulation ◽  
Air Temperature ◽  
Experimental Analysis ◽  
Experimental Results ◽  
Water Ice ◽  
Set Up ◽  
Time Required ◽  
The Impact

This paper describes an experimental set-up to evaluate the refrigeration loads for ice rink floors under controlled conditions. The ice-rink set-up was instrumented to measure the temperatures along various locations within the ice-rink floor including the water/ice layer. In addition, the energy used to freeze the water is monitored over the entire charging cycle to evaluate the performance of the ice rink floor for various insulation thermal resistance values (or R-values). Four floor insulation configurations are considered in the experimental analysis of R-0 (no insulation), R-4.2, R-6.7 and R-10 (in IP unit: hr.ft2.°F/Btu). The impact of the air temperature above the ice rink is also evaluated. The experimental results confirm that the addition of the thermal insulation beneath the ice-rink floor reduces the refrigeration load, decreased the time required to freeze the water above the ice rink, and helps maintain lower average ice temperature.

scholarly journals SIMULATION OF FUNCTIONAL CYCLE OF APPLICATION COMBAT MACHINE OF THE MOBILE WEAPONS COMPLEX

2020 ◽  
pp. 42-51
Author(s):  
Yu.O. Danilov ◽  
L.O. Khrol ◽  
A.V. Bologov ◽  
S.V. Moshnoy ◽  
L.V. Solodeeva
Keyword(s):  
Critical Path ◽  
Total Duration ◽  
Armed Conflicts ◽  
Systematic Analysis ◽  
Time Of Application ◽  
Combat Vehicle ◽  
Simulation Results ◽  
Time Required ◽  
The Impact ◽  
Estimation Of Time

The results of the analysis of the experience of creation of reconnaissance and strike complexes by the leading countries of the world and the possibility of their application in the implementation of the concepts of war based on the results of armed conflicts in recent years are presented. The purpose of the study is to conduct a systematic analysis of the duration of the functional cycle of the combat vehicle of the mobile weapon complex in the conditions of fire influence of modern means of air attack of the enemy and reconnaissance and strike systems. The logistic model of estimation of time of application of the fighting machine of a mobile complex of armament in the course of operation is offered. The logistics model allows to calculate the total duration of the functional cycle of combat use of the combat vehicle of the mobile armament complex. The study of the time characteristics of the process of using a combat vehicle is carried out using the critical path method. The calculation of the model allows to determine the operations of the critical path of the combat vehicle, the execution time of the functional cycle combat work. In solving the problem of calculating the time required to perform the functional cycle of the combat vehicle, for the initial data used standards for operations of a known type of weapon. The simulation results are proposed to be used in assessing the impact of the time of the functional cycle on the combat effectiveness of the combat vehicle. Such results are the basis for the formation of requirements for the tactical and technical characteristics of the combat vehicle of the mobile armament complex. The simulation results allow to determine the mathematical expectation of the time of execution of the functional cycle of the combat vehicle in order to ensure the required level of survivability and to set requirements for the mobility parameters of transport units of advanced combat vehicles of mobile weapons systems.

Influence of the distribution of the shear walls on the seismic response of the buildings

2020 ◽  
Vol 15 (1) ◽  
pp. 37-44
Author(s):  
El Mehdi Echebba ◽  
Hasnae Boubel ◽  
Oumnia Elmrabet ◽  
Mohamed Rougui
Keyword(s):  
Structural Analysis ◽  
Seismic Response ◽  
Natural Frequency ◽  
Structural Design ◽  
Structural Response ◽  
Shear Walls ◽  
Structural Elements ◽  
Analysis Software ◽  
Ansys Apdl ◽  
The Impact

Abstract In this paper, an evaluation was tried for the impact of structural design on structural response. Several situations are foreseen as the possibilities of changing the distribution of the structural elements (sails, columns, etc.), the width of the structure and the number of floors indicates the adapted type of bracing for a given structure by referring only to its Geometric dimensions. This was done by studying the effect of the technical design of the building on the natural frequency of the structure with the study of the influence of the distribution of the structural elements on the seismic response of the building, taking into account of the requirements of the Moroccan earthquake regulations 2000/2011 and using the ANSYS APDL and Robot Structural Analysis software.

Exile, Diaspora, and Return

2017 ◽  
Author(s):  
Luis Roniger ◽  
Leonardo Senkman ◽  
Saúl Sosnowski ◽  
Mario Sznajder
Keyword(s):  
Systematic Analysis ◽  
The Arts ◽  
Scientific Disciplines ◽  
Early Twenty ◽  
Transnational Connections ◽  
Late Twentieth ◽  
Institutional Impact ◽  
Global Arena ◽  
Education Science ◽  
The Impact

This book explores how Argentina, Chile, Paraguay, and Uruguay have been affected by postexilic relocations, transnational migrant displacements, and diasporas. It provides a systematic analysis of the formation of exile communities and diaspora politics, the politics of return, and the agenda of democratization in the late twentieth and early twenty-first centuries, focusing on the impact of intellectuals, academics, activists, and public figures who had experienced exile on the reconstitution and transformation of their societies following democratization. Readers are offered a kaleidoscope of intellectual itineraries, debates, and contributions held in the public domain by individuals who confronted and fought authoritarian rule. The book covers their contributions to the restructuring and transformation of scientific disciplines and of the humanities and the arts, as well as their collective institutional impact on higher education, science and technology, and public institutions. Bringing together sociopolitical, cultural, and policy analysis with the testimonies of dozens of intellectuals, academics, political activists, and policymakers, the book addresses the impact of exile on people’s lives and on their fractured experiences, the debates and prospects of return, the challenges of dis-exile and postexilic trends, and, finally, the ways in which those who experienced exile impacted democratized institutions, public culture, and discourse. It also follows some crucial shifts in the frontiers of citizenship, moving analysis to transnational connections and permanent diasporas, including the diasporas of knowledge that increasingly changed the very meaning of being national and transnational, while connecting those countries to the global arena.

What's Left of the Law of Integration?

2018 ◽  
Author(s):  
Julio Baquero Cruz
Keyword(s):  
International Law ◽  
Fundamental Rights ◽  
Structural Elements ◽  
The European Union ◽  
Difficult Situation ◽  
Court Of Justice ◽  
Structural Connections ◽  
The Law ◽  
Constitutional Pluralism ◽  
The Impact

This book discusses the impact of the difficult situation the European Union is currently going through on some structural elements of its legal order, looking for symptoms of decay, exploring examples of resistance, and assessing its overall state of health. The original choices made by the drafters of the Treaties and by the Court of Justice are put in their proper historical perspective, understanding Union law as a tool of civilization, and explaining its current problems, at least in part, as a consequence of the waning of the initial impetus behind integration. The concrete themes to be explored are the following: primacy, the national resistance to it and constitutional pluralism; the preliminary rulings procedure; Union citizenship, equality, and human dignity; the scope of the Charter and the standard of protection of fundamental rights; and the rigidity and fragmentation of the Union system in connection with the recent occasional use of international law as an alternative to Union law. The book looks at the development of the law throughout the decades, inevitably losing much detail, but hopefully also uncovering structural connections and continuities.

scholarly journals Exoplanet mass estimation for a sample of targets for the Ariel mission

2021 ◽  
Author(s):  
J. R. Barnes ◽  
C. A. Haswell
Keyword(s):  
Radial Velocity ◽  
Input Parameter ◽  
Noise Sources ◽  
Time Commitment ◽  
Low Mass ◽  
Time Required ◽  
Fixed Input ◽  
The Impact ◽  
Quadrature Sampling

AbstractAriel’s ambitious goal to survey a quarter of known exoplanets will transform our knowledge of planetary atmospheres. Masses measured directly with the radial velocity technique are essential for well determined planetary bulk properties. Radial velocity masses will provide important checks of masses derived from atmospheric fits or alternatively can be treated as a fixed input parameter to reduce possible degeneracies in atmospheric retrievals. We quantify the impact of stellar activity on planet mass recovery for the Ariel mission sample using Sun-like spot models scaled for active stars combined with other noise sources. Planets with necessarily well-determined ephemerides will be selected for characterisation with Ariel. With this prior requirement, we simulate the derived planet mass precision as a function of the number of observations for a prospective sample of Ariel targets. We find that quadrature sampling can significantly reduce the time commitment required for follow-up RVs, and is most effective when the planetary RV signature is larger than the RV noise. For a typical radial velocity instrument operating on a 4 m class telescope and achieving 1 m s−1 precision, between ~17% and ~ 37% of the time commitment is spent on the 7% of planets with mass Mp < 10 M⊕. In many low activity cases, the time required is limited by asteroseismic and photon noise. For low mass or faint systems, we can recover masses with the same precision up to ~3 times more quickly with an instrumental precision of ~10 cm s−1.

scholarly journals Fire Resistance Behaviour of Geopolymer Concrete:An Overview

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 82
Author(s):  
Salmabanu Luhar ◽  
Demetris Nicolaides ◽  
Ismail Luhar
Keyword(s):  
Compressive Strength ◽  
Thermal Resistance ◽  
Building Materials ◽  
Elevated Temperatures ◽  
Construction Materials ◽  
Flexural Behavior ◽  
Thermal Shrinkage ◽  
Physico Chemical ◽  
The Impact ◽  
Loss Of Strength

Even though, an innovative inorganic family of geopolymer concretes are eye-catching potential building materials, it is quite essential to comprehend the fire and thermal resistance of these structural materials at a very high temperature and also when experiencing fire with a view to make certain not only the safety and security of lives and properties but also to establish them as more sustainable edifice materials for future. The experimental and field observations of degree of cracking, spalling and loss of strength within the geopolymer concretes subsequent to exposure at elevated temperature and incidences of occurrences of disastrous fires extend an indication of their resistance against such severely catastrophic conditions. The impact of heat and fire on mechanical attributes viz., mechanical-compressive strength, flexural behavior, elastic modulus; durability—thermal shrinkage; chemical stability; the impact of thermal creep on compressive strength; and microstructure properties—XRD, FTIR, NMR, SEM as well as physico-chemical modifications of geopolymer composites subsequent to their exposures at elevated temperatures is reviewed in depth. The present scientific state-of-the-art review manuscript aimed to assess the fire and thermal resistance of geopolymer concrete along with its thermo-chemistry at a towering temperature in order to introduce this novel, most modern, user and eco-benign construction materials as potentially promising, sustainable, durable, thermal and fire-resistant building materials promoting their optimal and apposite applications for construction and infrastructure industries.

scholarly journals University students’ representations of Europe and self-identification as Europeans: a synthesis of qualitative evidence for future policy formulation

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Esther Cores-Bilbao ◽  
María del Carmen Méndez-García ◽  
M. Carmen Fonseca-Mora
Keyword(s):  
University Students ◽  
Evidence Synthesis ◽  
Foreign Language Learning ◽  
Educational Interventions ◽  
Policy Formulation ◽  
Qualitative Evidence Synthesis ◽  
The European Union ◽  
Systematic Analysis ◽  
Qualitative Evidence ◽  
The Impact

AbstractThe current European context is characterised by the emergence of socio-political tensions that threaten to derail the cohesion objectives traditionally promoted by the authorities of the European Union. With EU citizenship in the shadow of Brexit, the fear of dismemberment of the current Europe of the 28 looms over a renewed debate on concepts like European identity, European citizenship or EU legitimacy and the involvement of its constituents in European affairs, as well as the role of education for promoting democratic awareness among young Europeans. This work aims to collect, appraise and synthesise qualitative evidence obtained in primary research exploring the perceptions of European university students about their civic and cultural identity. This systematic analysis sets out to identify predictors of positive self-identification with the EU and its institutions, focusing on the impact that different educational interventions have had on the attitudes and perceptions expressed by university students, and the importance of foreign language learning in the results obtained. The authors report their assessment of quality of the findings in a Cochrane-style qualitative evidence synthesis (QES), based on the GRADE-CERQual (Confidence in Evidence from Reviews of Qualitative research) method. The 12 informed findings described in this study support decision-making in future education policy formulation.

Wavelength and threshold current variation in inhomogeneously pumped InGaAs/AlGaAs single and double quantum well ridge wave-guide lasers

1992 ◽  
Vol 70 (10-11) ◽  
pp. 908-913
Author(s):  
K. A. McGreer ◽  
D. Moss ◽  
R. L. Williams ◽  
M. Dion ◽  
D. Landheer
Keyword(s):  
Quantum Well ◽  
Threshold Current ◽  
Wave Guide ◽  
Double Quantum ◽  
Wavelength Shift ◽  
Exponential Dependence ◽  
Lasing Wavelength ◽  
Output Wavelength ◽  
Double Quantum Well ◽  
Current Variation

We investigate the wavelength and threshold current variation with passive wave-guide length in inhomogeneously pumped single and double quantum well InGaAs/AlGaAs strained layer ridge wave-guide lasers. We observe a linear and extremely low increase in threshold current with unpumped length, both for single and double quantum well lasers. A large red shift in the lasing wavelength as the unpumped length is increased is also observed. We present a model, based on absorption saturation in the unpumped section, which describes both the wavelength shift and the threshold current variation. The increase in threshold current that we observe is much smaller than results reported in the literature for GaAs/AlGaAs lasers, where a large exponential dependence was attributed to gain saturation in the pumped section. Because the threshold current does not dramatically vary with unpumped length for our lasers, this is a potentially useful technique for shifting the output wavelength of the laser. Finally, we investigate the wavelength tuning behavior of lasers having two segments pumped with different currents. A wavelength tunability of ~13 nm for the DQW laser was observed.

Analysis and Reduction of the Waste in the Work Process Using Time Study Analysis: A Case Study

2014 ◽  
Vol 660 ◽  
pp. 971-975 ◽  
Author(s):  
Mohd Norzaim bin Che Ani ◽  
Siti Aisyah Binti Abdul Hamid
Keyword(s):  
Cycle Time ◽  
Lean Manufacturing ◽  
Value Added ◽  
Time Study ◽  
Study Approach ◽  
Root Cause ◽  
Wide Range ◽  
Unit Of Work ◽  
Time Required ◽  
The Impact

Time study is the process of observation which concerned with the determination of the amount of time required to perform a unit of work involves of internal, external and machine time elements. Originally, time study was first starting to be used in Europe since 1760s in manufacturing fields. It is the flexible technique in lean manufacturing and suitable for a wide range of situations. Time study approach that enable of reducing or minimizing ‘non-value added activities’ in the process cycle time which contribute to bottleneck time. The impact on improving process cycle time for organization that it was increasing the productivity and reduce cost. This project paper focusing on time study at selected processes with bottleneck time and identify the possible root cause which was contribute to high time required to perform a unit of work.

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